Abstract

Ultra-smooth surfaces with low contamination and little damage are a great challenge for aluminum optical fabrication. Ion beam sputtering (IBS) has obvious advantages of low contamination and non-contact that make it a perfect method for processing aluminum optics. However, the evolution laws of aluminum surface morphology are quite different from conventional amorphous materials, which affects the roughness change and needs systematic research. Thus, in this paper, the roughness evolution of an aluminum optical surface (i.e., aluminum mirror) subjected to IBS has been studied with experimental and theoretical methods. The surface morphology evolution mechanisms of turning marks and second phase during IBS are revealed. The newly emerging relief morphology and its evolution mechanism are studied in depth. The experimental results find that IBS causes the coarsening of optical surfaces and the appearance of microstructures, leading to the surface quality deterioration. Turning marks have been through the process of deepening and vanish, while second phase generates microstructures on the original surface. The corresponding mechanism is discussed exhaustively. Preferential sputtering, curvature-dependent sputtering and material properties play important roles on surface quality deterioration. A modified roughness evolution mechanism and an improved binary sputtering theory are proposed to describe the polycrystalline sputtering phenomena. The current research can provide a guidance for the application of IBS in aluminum optics manufacture fields.

© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

1. Introduction

With fine mechanical property, light weight and high reflectivity, aluminum is widely used in optical systems in recent years, especially in the micro-satellites with extreme requirements for weight and volume [14], such as SCUBA-2. The preferred aluminum alloy is 6061 which has relatively manufacturability, stiffness, and strength to weight ratio [5]. Currently, the applied optical frequency band of imaging aluminum optics is moving from infrared (IR) and far infrared (FIR) to visible (VIS) and ultra violet (UV). Most of the challenges for aluminum optical fabrication center on achieving ultra-smooth surfaces with nanometer roughness and damage-free surface [6,7]. Usually, aluminum optics are fabricated by Single Point Diamond Turning (SPDT). With the rapidly growing demand for precision optical components such as freeform surfaces, SPDT is continuously improved in control and tool design [8,9]. Currently, SPDT can achieve optical freeform surface with micrometer to submicrometer form accuracy and nanometer range surface roughness. However, machining precision of SPDT is limited by the accuracy of machine tools. To improve form accuracy and surface roughness, further polishing processes are needed. But aluminum have properties of high chemical reactivity and low surface hardness, and most of regular polishing processes involve the usage of abrasive particles, physical force and chemical reagent, leading to risks of scratches and contamination that are often associated with reduction in surface roughness [10]. As a high precision machining process, Ion Beam Sputtering (IBS) achieves figure correction by removing materials through physic sputtering effect, which is a non-contact and highly stable method [11,12]. During IBS process, no mechanical force is applied on the surface which will induce zero scratch. Also, the whole process is conducted in a near-vacuum environment which will not cause contamination. All the advantages are shown that IBS can be a better polishing method for aluminum optics.

In recent years, more researches have been focused on the roughness and surface morphology revolution during IBS. Remarkable works are done to reveal the formation mechanism of different micro-topography, such as ripples [13,14], nano particles [15,16]. Surface material state and IBS process conditions such as incident angle [17] were believed to strongly affect the surface micro-topography changes. However, most of the researches are conducted on amorphous materials such as fused silica or monocrystalline materials such as silicon. There is a great lack of studies about metal materials. In 1992, A systematic experiment was carried out by C.M. Egert about roughness evolution of different materials during ion beam sputtering [18]. Metal materials such as Al and Cu show poor performance on roughness decrease. Few researches are done since then. However, in recent years, there are a few scattered studies shows that IBS can also be used in metal optics manufacture in certain conditions [19,20]. Though achieving good results, the mechanism is not fully revealed. Moreover, the aluminum optic surfaces show a more complicated state before further polishing. First, aluminum 6061 is ternary alloy with the characteristics of polycrystal and containing miscellaneous aging precipitates [21]. Secondly, before further polishing, aluminum optics are usually processed by SPDT which will generate periodic turning marks on the optical surface [22,23]. Therefore, the work surface presents a complicated state leading a complex coupling evolution mechanism of surface morphology. Consequently, it is valuable and urgent to study the evolution of morphology and surface roughness of aluminum optics during IBS.

In this paper, based on the IBS experiment, the roughness evolution regularity of aluminum alloy optical surface during IBS is summarized, and the key factors affecting surface roughness are identified. The evolution mechanisms of different morphologies are thoroughly expounded by experimental and theoretical analysis. The revealed evolution mechanism and regularity will provide a guidance for application of IBS technology in aluminum optics manufacture fields.

2. Experiment details

2.1. Single point diamond turning

Three samples are prepared by Precitech Nanoform 350 Ultra lathe with same turning parameters to ensure the same surface state and roughness. The turning parameters are given in Table 1. All the sample surfaces maintain the similar roughness around 2.9∼3.3 nm Ra after SPDT. The size of sample A is ϕ80mm×10 mm. the size of sample B and sample C is 100mm×100mm×10 mm.

Tables Icon

Table 1. Parameters of SPDT process

Typical compositions of aluminum alloy (6061-1) are presented in Table 2.

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Table 2. Composition of aluminum alloy

2.2. Ion beam sputtering

The IBS experiments are performed in our self-developed IBS systems (KDIBF650L-VT) under the bombardment of Ar+ ions at normal incidence with the work pressure of 2.5×10−3Pa. A trench etching method is used in the experiment to generate a continuously depth distribution as shown in Fig. 1.

 figure: Fig. 1.

Fig. 1. IBS trench etching method

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We choose a maximum itching depth of 1000 nm in which most of the surface-shape error generated by SPDT can be eliminated [19]. The removal rate of aluminum is a determinate value. With the specific processing time matrix, a trench can be easily generated. Trench etching method is more conductive for observation and analysis of surface quality evolution [15]. However, in the study of morphology evolution of turning marks and second phase, the layer-by-layer removal method is more conducive for observation. The parameters of IBS experiment are given in Table 3.

Tables Icon

Table 3. Parameters of IBS process

The surface-shape before and after IBS is measured by ZYGO VeriFire Asphere 6 inches Interferometer to determine the depth of trench. The location of points to be measured is marked at specific depth. Carl Zeiss Primotech MAT Metallographic Microscope (MM), ZYGO NV700S White Light Interferometry (WLI) are used to observe the morphology and roughness evolution in the different depth of the trench. WLI measurement is performed at 20× lens with a scan size of 0.47mm×0.35 mm. At each etching depth, three different position are selected, the average of roughness value Ra is taken as the roughness value of corresponding depth. As for morphology evolution observation, WLI is competent in turning marks evolution observation. However, considering that the size of second phase is on the micron scale, the Bruker Dimension Icon atomic force microscope (AFM) is used for second morphology evolution observation. AFM measurements are performed at a fixed scan size of 20µm×20µm with a resolution of 512×512pixels and a scan rate of 1.0 Hz.

For completeness, the IBS experiments are repeated at sample B and sample C under different IBS parameters. The ion energy E ranges from 600 eV to 800 eV. The beam current J ranges from 10 mA to 20 mA. The experiment parameters are shown in Table 4. Three trenches are etched on each sample. Considering the sample size, 5 mm beam diameter is chosen.

Tables Icon

Table 4. Parameters of IBS process

3. Experiment results and analysis

3.1. Surface roughness evolution of aluminum optics

Data fitting of roughness values is shown in Fig. 2. surface roughness increases rapidly with the increase of removal depth. The evolution regularity can be revealed as four sections. Firstly, surface roughness value shows an exponential growth regularity and finally reaches 10∼12 nm at the removal depth of 80∼83 nm. Then, growth rate of roughness slows down. Second section ends with the roughness value reaching 13∼15 nm at the removal depth of 118∼120 nm. At third section, roughness value increases steadily in a linear pattern and finally reaches 48∼56 nm at the removal depth of 250∼260 nm. With further increase of IBS removal depth, the roughness maintains a steady value.

 figure: Fig. 2.

Fig. 2. Data fitting of roughness with different removal depth (Sample A)

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Figure 3 shows the typical surface morphology during the IBS process. With different removal depth, the surface morphology present distinct differences in different sections. Troughs and relief structures with size of micrometer emerge on the surface during IBS process. It is worth mentioning that initial surface morphology is not preserved. Compared with experiment on amorphous materials, morphology evolution of aluminum optic shows great novelty and complexity which need to be studied.

 figure: Fig. 3.

Fig. 3. Surface morphology and roughness evolution with different IBS removal depths (sample A). (a)original surface. (b) IBS removal 50 nm. (c) IBS removal 65 nm. (d) IBS removal 100 nm. (e) IBS removal 170 nm. (f) IBS removal 400 nm.

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For completeness, trench experiments are repeated on sample B and C. Data fittings are shown on Fig. 4. The surface roughness keeps rising when removal depth increases. Even though at different voltages and currents, the variations of roughness remain same regularity and finally reaches stability at about 51 nm. These results reveal that the processing parameter, such as voltage and current, has limited effects on the surface roughness. In contrast, the inherent properties of aluminum material play a dominant role in the roughness evolution during IBS process.

 figure: Fig. 4.

Fig. 4. Data fitting of roughness with different removal depth (a) at different voltages while the current maintains 10 mA (Sample B), and (b) at different currents while the voltage maintains 700 eV (Sample C).

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3.2. Micro-morphology evolution of second phase

Quaternary precipitates with Al5Cu2Mg8Si6 stoichiometry are reported to be formed the Al6061 matrix during the initial alloy annealing procedure. However, second phase, to be more specific, Mg2Si will commonly form during the aging process because of its low solubility. Generally speaking, crystal defects such as grain boundaries, dislocations can be the priority region for second phase generating. With higher hardness (usually 5 times higher that substrate) [5], during turning process, abrupt hardness changing causes defects (Micro-sized crest) on the finished surfaces causing severely roughness deterioration as shown in Fig. 3(a). After IBS, troughs morphology with micro-scale depth is shown on the surface. With help of Scanning Electron Microscope (Hitachi S-4800) and Energy Dispersive Spectrometer (HORIBA EX250), micro-morphology and composition distribution are shown in Fig. 5.

 figure: Fig. 5.

Fig. 5. SEM, EDS tests after IBS (a) Microscope images, (b) SEM amplifying image of region frames, (c) EDS test of area 1, (d) EDS test of area 2

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The morphology of surface in Fig. 5(a) matches well with the test result of WLI in Fig. 3(c). The relief emerges obviously on finished surface, as shown in the red dotted box. The troughs are mainly distributed on the boundary of relief. The EDS test reveals that the main composition of trough region (area 2 in Fig. 5(b)) is Al, Mg and Si, among which Mg and Si are the constituent elements of the second phase Mg2Si in the 6061-aluminum alloy [21]. While in area 2, the area without troughs, the constituent element is aluminum for other elements are too little to be tested. Results indicate that second phase crest will preferential sputtered, leaving trough topography on the surface.

Figure 6 shows the morphology evolution of second phase. Since the size of second phase (1∼2µm) is relatively small, AFM was used to revealing the morphology evolution after each IBS process. It is obvious that the second phase are preferential sputtered from the surface leaving troughs morphology on the surface. With increasing removal depth, the width and depth of second phase trough increases rapidly. The adjacent troughs gradually approach each other and finally connect and merge forming texture structure on the surface as shown on Fig. 3(b) and Fig. 6(f). As mentioned above, grain boundaries are the priority region for second phase generating. As a result, second-phase texture will protrude the grains as shown in Fig. 3(c) and finally form relief morphology.

 figure: Fig. 6.

Fig. 6. Morphology evolution of second phase different IBS removal depths and corresponding 3D topography. (a)(d) original surface, (b)(e) IBS removal 40 nm, (c)(f) IBS removal 80 nm.

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The morphology evolution process can be referred as two stages: First, the second phase crest evolves to a trough. Then, the transverse dimension of the trough expands and adjacent troughs are merged, forming a relief morphology.

3.3. Micro-morphology evolution of turning marks

Figure 7 shows the morphology evolution of turning marks. After removing 40 nm, turning marks become more obvious comparing with the original surface as shown in Fig. 7(a). With the IBS removal depth increase to 80 nm, relief morphology appears and cuts off turning marks. However, turning marks still can be observed on the relief structures. In Fig. 7(d), with increase amount of relief structures, turning marks can hardly be observed on the surface.

 figure: Fig. 7.

Fig. 7. Morphology evolution of turning marks. (a) original surface, (b) IBS removal 40 nm, (c) IBS removal 80 nm, (d) IBS removal 120 nm.

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Figure 8 shows the corresponding line profiles of WLI images in Fig. 7. The line profiles are sampled at the same section perpendicular to the turning marks. Original surface line profile (red dotted line) shows periodicity with amplitude of 4 nm. After remove 40 nm, there is still periodicity but amplitude increases to approximately 12 nm. As the removal depth increases, amplitude continue increasing. However, periodicity is no longer apparent. When IBS removal depth comes to 120 nm, line profile shows evident demarcated region which means relief structures dominate surface morphology evolution.

 figure: Fig. 8.

Fig. 8. the corresponding line profiles of WLI images in Fig. 7.

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Figure 9 gives the Power Spectral Density (PSD) analysis of different IBS removal depth corresponding to Fig. 7. Considering the original turning marks amplitude is rather small and second phase quantity is quite large, the turning marks peaks didn’t appear on the PSD of original surface. After IBS removal 40 nm, the surface shows two peaks of 243 mm-1 and 492 mm-1 in the PSD curve, corresponding to the spatial sizes of turning marks and second phase troughs, which are 4 µm and 2 µm, respectively. In contrast, the peak of 492 mm-1 disappears in the PSD curve under 80 nm removal. This is because the second phase merges and form texture structures. Furthermore, only the weakened peak of 243 mm-1 exists on the PSD curve, consistent with the result shown in Fig. 7(c) that the turning marks are obvious weakened. With increase of removal depth, PSD curve continues increasing which indicates that surface roughness will continue deteriorating.

 figure: Fig. 9.

Fig. 9. PSD analysis with different removal depth corresponding to Fig. 7.

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The morphology evolution process can be referred as two stages. First, turning marks amplitude increases with the rising removal depth. Then, the turning marks is weakened and eliminated because of the emerging relief morphology.

4. Mechanism and discussion

In this section, the morphology evolution mechanisms of second phase, turning marks during IBS process are discussed. An improved roughness evolution mechanism of polycrystal materials is proposed. On that basis, the roughness evolution regularity is revealed.

4.1. Influence of material properties and surface topography

At the first stage of second phase morphology evolution, the second phase crest evolves to a trough. At this stage, the evolution mechanism is mainly caused by material properties. The average size of second phase is 1∼2 µm. According to Fig. 3(b), the depth of the second phase troughs approaches the scale of micron which means that most of the second phase is removed. The influence of material properties on the morphology evolution is weakened or even disappears.

Consequently, the morphology evolution mechanism is highly dependent on the local topography at the second stage. According to Sigmund’s theory, sputtering rate can be increased as the incident angle increasing (usually the critical angle is 65°∼80°) [15,24]. Thus, larger gradient of pit slope will receive higher sputtering rate when surface is subjected to normally ion beam bombardment. Since transverse and longitudinal dimension of troughs are closer in size, critical angle can be easily reached. When the ion beam has perpendicular incidence to the troughs, the incidence angle effect will make the side wall of the troughs extend continuously, resulting in the increase of the transverse dimension.

As for troughs emerges shown in Fig. 6, the etching rate of the spike at the overlap is significantly higher than that of other areas. This is due to the large incidence angle in both sides of the spike, which increases the probability of receiving sputtering energy and is thus preferentially removed, as shown in Fig. 10.

 figure: Fig. 10.

Fig. 10. Morphology evolution of second phase

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At the first stage of turning marks morphology evolution, turning marks amplitude increases with the rising removal depth. According to Bradley and Harper (BH) theory, the average energy deposited at trough area is greater than crest area leading to a higher removal rate for the trough. Therefore, turning marks trough area will remove faster than crest area leading to continually increasing amplitude. Moreover, for turning marks, transverse dimension is significantly larger than longitudinal dimension as shown in Fig. 11. The incident angle will not reach the critical value so that spike weaken phenomenon is not evident.

 figure: Fig. 11.

Fig. 11. Morphology evolution of turning marks

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The merging second phase trough forms texture structure on the surface. Texture morphology protrudes the grains and cuts off turning marks at a specific removal depth (118nm∼120 nm).

4.2. Discussion about polycrystal states

Based on the above analysis, we can deduce that the influence of second phase and turning marks on roughness evolution is weakened even disappears when removal depth comes to 120 nm. As showed in Fig. 7(d), the emerged grains formed relief structures will dominate the morphology evolution mechanism. We refer it as grain sputtering state. However, randomly distributed grain orientations make evolution mechanism hard to analyzed. Based on definition of surface roughness Ra, we give a modified roughness evolution mechanism of this state. Ra can be given as follow:

$${R_a} = \frac{1}{l}\int_0^l {|{y(x)} |} dx,$$
where l is sampling length, y(x) is distance from the sampling point to the midline of the contour. For a specific crystal plane sputtering, we can assume that sputtering rate is constant because of the constant surface binding energy [25]. Figure 12(a) shows the plan view of grain sputtering state. We take a sample of length L. For simplicity, we made several assumptions based on experimental reality:
  • a. The surface morphology is an absolute plane at the beginning for we only need to investigate the variation of Ra.
  • b. Sample L is separate by n grains. Each grain is simplified as a cuboid for etching depth is far less than the size of grain in experiment.
  • c. Different grains have specific sputtering rate v and proportion Ci. The midline of contour has the sputtering rate of V.

 figure: Fig. 12.

Fig. 12. grain sputtering state (a)surface planform view, (b) sectional view of line L

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Based on the above assumption, midline sputtering rate V and Ra can be given as:

$$V = \sum\limits_{i = 1}^n {{C_i}{v_i}} ,$$
$${R_a} = t\sum\limits_{i = 1}^n {{C_i}|{V_i}} - V|,$$
where t is sputtering time. Assume that the first k velocities are greater than V, Eq. (3) can be rewritten as:
$${R_a} = 2t\sum\limits_{i = 1}^k {{C_i}({V_i}} - V),$$

For an aged alloy, it is believed to have homogeneous components. Therefore, ${C_i}$ can be simplified as 1/n. Ra can be further simplified as:

$$\begin{array}{c} {R_a} = \frac{{2t}}{{{n^2}}}[(n - k)\sum\limits_{i = 1}^k {{V_i}} - k\sum\limits_{j = k + 1}^n {{V_j}} ]\\ = \frac{{2t}}{{{n^2}}}(n - k)k({{\bar{V}}_i} - {{\bar{V}}_j}). \end{array}$$
where ${\bar{V}_i}$ and ${\bar{V}_j}$ represents mean value of sputtering rates that are above and below midline sputtering rate V respectively. n is a determined value for a specific material. For the same surveyed area, ${\bar{V}_i}$, ${\bar{V}_j}$ and k are constants. Moreover, we believed that aged alloy has homogeneous components. Thus, ${\bar{V}_i}$, ${\bar{V}_j}$ and k can be regarded as constants for fixed size surveyed area. We can deduce that Ra should increase in a linear pattern which is quite match with experiment results in Fig. 2.

Ra deterioration rate will be determined by n and k. Figure 13 shows the normalized Ra deterioration rate with the change of k at different n values. Deterioration rate has an inverted-U relationship with the k and reaches its max value when k equals n/2. For the same k/n value, deterioration rate will remain the same even when n increases (grain size decreases). However, due to the existence of crystal texture, k/n can reach a steady value only when the sampling area is large enough. For the fixed surveyed size, different grain sizes will have different k/n values. Generally speaking, with the grain size decreasing, k/n will gradually increase to a stable saturation value. In another word, materials with smaller grains will have a faster deterioration rate.

 figure: Fig. 13.

Fig. 13. Ra deterioration rate as a function of k at different n values

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4.3. Discussion about the steady roughness value

According to experimental results, the final roughness value will reach a steady value. To analyze the factors influencing the value, we improved Bradley and Shipman (BS) binary compounds sputtering theory [2630].

The surface atoms will be sputtered from the surface when they obtain enough energy from impinging ions. The energy deposited per unit surface is:

$$F = {F_0} + \alpha {\nabla ^2}h,$$
where F0 is F for plat surface. The constant α is positive which will lead to a surface instability. Considering polycrystalline alloy surface is sputtered at same condition and beam diameter is far larger than grain size, we assume that the deposited energy has identical form for all components in alloy.

On sputtering area O, assume that there are n lattice planes. For a specific lattice plane i, it is natural that the sputtering rate can be expressed as

$${Y_i} = {\Lambda _i}{F_i}{c_i}J,$$
where ci is concentration of lattice plane on the surface and J is the flux. Λi is constant proportionality relating the deposited power and rate of erosion which is determined by surface binding energy and scattering cross-section coefficient.

Also, there are atomic currents on the surface corresponding to surface smoothing. Surface diffusion mechanism on metal materials is thermal activated. According to BS theory, the surface current can be expressed as follow [31,32]:

$${J_i} ={-} {D_i}{n_s}\nabla {c_i} + \frac{{{D_i}{c_i}{n_s}\Omega {\gamma _s}}}{{{k_B}T}}\nabla {\nabla ^2}h - {\mu _i}\nabla h,$$
where Di is surface diffusivity of species i and has an Arrhenius form, γs is surface tension, kB is Boltzmann’s constant, Ω is the atomic volume. ns is the total number of mobile surface atoms. The positive constant µi characterizes the momentum transfer from the incident ions to atoms of lattice plane i ions.

The yield is:

$$\frac{{\partial h}}{{\partial t}} ={-} \Omega \sum\limits_{i = 1}^n {({F_i} + \nabla \cdot {J_i}} ),$$
We use Eqs. (6)-(8) to eliminate the Fi’s and Ji’s in Eq. (9). The yields can be expressed as:
$$\frac{{\partial h}}{{\partial t}} = A + B{\nabla ^2}h + C{\nabla ^2}{\nabla ^2}h,$$
where:
$$A ={-} \Omega {F_0}J(\sum\limits_{i = 1}^n {{c_i}} {\Lambda _i}),$$
$$B ={-} \Omega (J\alpha \sum\limits_{i = 1}^n {{c_i}} {\Lambda _i} - \sum\limits_{i = 1}^n {{\mu _i}} ),$$
$$C ={-} \frac{{{n_s}{\Omega ^2}{r_s}}}{{{k_B}T}}(\sum\limits_{i = 1}^n {{D_i}} {c_i}),$$
The PSD function can be obtained [33]:
$$PSDh(q,t) = PSD(q,t = 0)\exp (2C(q)t).$$
where C(q)=-Bq2+Cq4, q = f/2π and f is the spatial frequency. If C(q) < 0, the surface will tend to be smooth. From Eq. (14), we can assure C<0. Roughness increasing indicates -B>0 at whole spatial frequency. However, the value of -B decreases with the decrease of ci, which means smaller PSD value as well as smaller surface roughness can be achieved with decreasing ci value. In another word, materials with smaller grains will have lower steady surface roughness.

In order to verify theoretic analysis, another Al6061 material (6061-2) with bigger grains is used during the trench experiment. 6061-2 material presents similar evolution regularity to 6061-1 material as shown on Fig. 14(a). However, 6061-2 has lower roughness deterioration rate. At the third section when emerged grain dominate the morphology evolution mechanism, as presented on Fig. 14(b) the slope of 6061-1 is significantly higher than 6061-2 which verifies our analysis on Chapter 4.2. 6061-2 surface roughness value finally reaches 103 nm at removal depth of 2500 nm as shown on Fig. 14(a) which is significantly higher than 6061-1’s 51 nm. It verifies our analysis on Chapter 4.3.

 figure: Fig. 14.

Fig. 14. Data fitting of roughness with different removal depth, (a) roughness evolution of 6061-2, (b) comparison of 6061-1 and 6061-2 at range of 0∼1000 nm.

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4.4. Discussion on the evolution mechanism of the roughness evolution

Based on above analysis, we can explain the evolution regularity of surface roughness. After SPDT, periodic turning marks and second phase crest remaining on the surface determine the surface roughness. On the first section, after IBS removal certain depth, the second phase crest become troughs and continue to expand on transverse and longitudinal dimension. Also, amplitude of periodic turning marks is increase with the removal depth as shown in Fig. 3(b). Thus, the roughness value is rapidly increased. On the second section, second phase troughs form texture structure and protrude the grains. At this state, surface morphology varies to relief topology with the vanishment of turning marks and second phase. The surface roughness continues increasing at a lower rate comparing to first section as shown in Fig. 3(c). On the third section, relief morphology plays a dominant role on the surface roughness changes. One or several grains consist of one relief structure which has the same sputtering rate as shown in Figs. 3(d) and 3(e). The roughness increases at a linear pattern because of the polycrystalline sputtering. On the fourth section, the surface roughness reaches a steady value because the surface sputtering and thermal diffusion achieve balance as shown in Fig. 3(f).

The grain size of aluminum material plays a dominant role in the roughness evolution during IBS process. The effects mainly consist in two aspects.

  • (1) Grain size will affect the roughness increasing rate. With bigger grain size, roughness will increase slowly at the first three section. More obviously, on the third section, the linear slope is much lower for large grain size materials.
  • (2) Grain size will affect the final steady roughness value. With bigger grain size, the final steady roughness value will be much higher.

5. Conclusion

In summary, the surface roughness shows the unique evolution regularity when the aluminum mirror is subjected to the ion beam sputtering. Initial surface defects with different properties present different evolution laws during IBS which affects the roughness evolution regularity.

In this paper, surface morphology evolution of second phase and turning marks is comprehensively studied by experimental and theoretical methods. Results show that the material property and micro-topography are important factors affecting the evolution of surface morphology. With the removal depth increasing, turning marks and second phase are eliminated. The extremely special relief topography emerges. The formation and evolution of relief are studied in depth experimentally and theoretically. We found that grain size can be a key factor that affects the roughness evolution regularity for polycrystalline Al6061. To be more specific, large grain size will receive lower deterioration rate and higher steady roughness value.

Through the summary of the evolution of different morphology, the roughness evolution regularity is revealed. Based on the experimental results, we found that the roughness evolution regularity includes four stages. The first two stage is highly affected by morphology evolution of second phase and turning marks. The latter two stage is determined by relief morphology evolution. The revealed regularity and mechanism will lay a foundation for the application of IBS in aluminum optics manufacture fields.

Funding

National Natural Science Foundation of China (51991371).

Disclosures

The authors declare no conflicts of interest.

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14. A. Keller, S. Facsko, and W. Moller, “Evolution of ion-induced ripple patterns on SiO2 surfaces,” Nucl. Instrum. Methods Phys. Res., Sect. B 267(4), 656–659 (2009). [CrossRef]  

15. M. J. Xu, Y. F. Dai, L. Zhou, X. Q. Peng, S. S. Chen, and W. L. Liao, “Evolution mechanism of surface roughness during ion beam sputtering of fused silica,” Appl. Opt. 57(20), 5566–5573 (2018). [CrossRef]  

16. N. I. Chkhalo, S. A. Churin, M. S. Mikhaylenko, A. E. Pestov, V. N. Polkovnikov, N. N. Salashchenko, and M. V. Zorina, “Ion-beam polishing of fused silica substrates for imaging soft x-ray and extreme ultraviolet optics,” Appl. Opt. 55(6), 1249–1256 (2016). [CrossRef]  

17. W. L. Liao, Y. F. Dai, and X. H. Xie, “Nanopatterning of optical surfaces during low-energy ion beam sputtering,” Opt. Eng. 53(6), 065108 (2014). [CrossRef]  

18. C.M. Egert, “Roughness evolution of optical materials induced by ion beam milling,” Proc. SPIE 1752, 63–72 (1992). [CrossRef]  

19. J. Bauer, F. Frost, and T. Arnold, “Reactive ion beam figuring of optical aluminum surfaces,” J. Phys. D: Appl. Phys. 50(8), 085101 (2017). [CrossRef]  

20. Y. T. Huang, B. Fan, Y. J. Wan, and S. J. Li, “Improving the performance of single point diamond turning surface with ion beam figuring,” Optik 172, 540–544 (2018). [CrossRef]  

21. G.P.H Gubbels, B.W.H van Venrooy, A. J. Bosch, and R. Senden, “Rapidly solidified aluminum for optical applications,” Proc. SPIE 7018, 70183A (2008). [CrossRef]  

22. Y. Gong and L. Zhao, “Single point diamond machine and their applications to optical engineering,” Chin. Opt. 4, 537–545 (2011).

23. S. Risse, A. Gebhardt, C. Damm, T. Peschel, W. Stockl, T. Feigl, S. Kirschstein, R. Eberhardt, N. Kaiser, and A. Tunnermann, “Novel TMA telescope based on ultra-precise metal mirrors,” Proc. SPIE 7010, 701016 (2008). [CrossRef]  

24. P. Sigmund, Theory of sputtering. I. “Sputtering yield of amorphous and polycrystalline targets,” Phys. Rev. 184(2), 383–416(1969). [CrossRef]  

25. T. V. Panova, V. I. Blinov, V. S. Kovivchak, G. I. Gering, and D. V. Konstantinov, “Formation of preferred orientations in Aluminum, Copper, and Nickel Irradiated with Intense Ion Beams,” J. Synch. Investig. 1(2), 197–203 (2007). [CrossRef]  

26. P. D. Shipman and R. M. Bradley, “Theory of nanoscale pattern formation induced by normal-incidence ion bombardment of binary compounds,” Phys. Rev. B 84(8), 085420 (2011). [CrossRef]  

27. R. M. Bradley, “Surface instability of binary compounds caused by sputter yield amplification,” Appl. Phys. Rev. 111(11), 114305 (2012). [CrossRef]  

28. R. M. Bradley and P. D. Shipman, “A surface layer of altered composition can play a key role in nanoscale pattern formation induced by ion bombardment,” Appl. Surf. Sci. 258(9), 4161–4170 (2012). [CrossRef]  

29. R. M. Bradley, “Nanoscale compositional binding in binary thin films produced by ion-assisted deposition,” J. Appl. Phys. 114(22), 224306 (2013). [CrossRef]  

30. R. M. Bradley, “Morphological transition in nanoscale patterns produced by concurrent ion sputtering and impurity co-deposition,” J. Appl. Phys. 119(13), 134305 (2016). [CrossRef]  

31. V. B. Shenoy, W. L. Chan, and E. Chason, “Compositionally modulated ripples induced by sputtering of alloy surfaces,” Phys. Rev. Lett. 98(25), 256101 (2007). [CrossRef]  

32. S. Sarkar, B. V. Daele, and W. Vandervorst, “Impact of repetitive and random surface morphologies on the ripple formation on ion bombardment SiGe-surfaces,” New J. Phys. 10(8), 083012 (2008). [CrossRef]  

33. T. M. Mayer, E. Chason, and A. J. Howard, “Roughening instability and ion -induced viscous relaxation of SiO2 surfaces,” J. Appl. Phys. 76(3), 1633–1643 (1994). [CrossRef]  

References

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  1. A. Bauer and J. P. Rolland, “Visual space assessment of two all-reflective, freeform, optical see-through head-worn displays,” Opt. Express 22(11), 13155–13163 (2014).
    [Crossref]
  2. Y. Wang, Z. Li, X. Liu, and F. Fang, “Freeform-objective Chernin multipass cell: application of a freeform surface on assembly simplification,” Appl. Opt. 56(30), 8541–8546 (2017).
    [Crossref]
  3. L. Y. Yuan, Z. P. He, G. Lv, Y. M. Wang, C. L. Li, J. N. Xie, and J. Y. Wang, “Optical design, laboratory test, and calibration of airborne long wave infrared imaging spectrometer,” Opt. Express 25(19), 22440–22454 (2017).
    [Crossref]
  4. Z. Li, X. Liu, F. Fang, and X. Zhang, “Integrated manufacture of a freeform off-axis multi-reflective imaging system without optical alignment,” Opt. Express 26(6), 7625–7637 (2018).
    [Crossref]
  5. L. Wamboldt, B. Roy, J. Crifasi, S. Stephens, D. Hanninen, K. Woodard, R. Felock, S. Polczwartek, and J. Parenteau, “An ultra-low surface finish process for 6061-Al mirrors,” Proc. SPIE 9451, 945111 (2015).
    [Crossref]
  6. C. C. Wang, S. C. Lin, and H. Hong, “A material removal model for polishing glass-ceramic and aluminum magnesium storage disk,” Int. J. Mach. Tool Manu. 42(8), 979–984 (2002).
    [Crossref]
  7. Y. Ahn, J. Y. Yoon, C. W. Baek, and Y. K. Kim, “Chemical mechanical polishing by colloidal silica-based slurry for micro-scratch reduction,” Wear 257(7-8), 785–789 (2004).
    [Crossref]
  8. L. Li and A. Y. Yi, “Design and fabrication of a freeform microlens array for a compact large-field-of-view compound-eye camera,” Appl. Opt. 51(12), 1843–1852 (2012).
    [Crossref]
  9. Z. X. Feng, B. D. Froese, C. Y. Huang, D. L. Ma, and R. G. Liang, “Creating unconventional geometric beams with large depth of field using double freeform-surface optics,” Appl. Opt. 54(20), 6277–6281 (2015).
    [Crossref]
  10. Y. L. Wang, J. Wu, C. W. Liu, T. C. Wang, and J. W. Dun, “Material characteristics and chemical-mechanical polishing of aluminum alloy thin films,” Thin Solid Films 332(1-2), 397–403 (1998).
    [Crossref]
  11. M. Weiser, “Ion beam figuring for lithography optics,” Nucl. Instrum. Methods Phys. Res., Sect. B 267(8-9), 1390–1393 (2009).
    [Crossref]
  12. F. Frost, R. Fechner, B. Ziberi, J. Vollner, D. Flamm, and A. Schindler, “Large area smoothing of surfaces by ion bombardment: fundamentals and applications,” J. Phys.: Condens. Matter 21(22), 224026 (2009).
    [Crossref]
  13. R. M. Bradley and J. M. E. Harper, “Theory of ripple topography induced by ion bombardment,” J. Vac. Sci. Technol., A 6(4), 2390–2395 (1988).
    [Crossref]
  14. A. Keller, S. Facsko, and W. Moller, “Evolution of ion-induced ripple patterns on SiO2 surfaces,” Nucl. Instrum. Methods Phys. Res., Sect. B 267(4), 656–659 (2009).
    [Crossref]
  15. M. J. Xu, Y. F. Dai, L. Zhou, X. Q. Peng, S. S. Chen, and W. L. Liao, “Evolution mechanism of surface roughness during ion beam sputtering of fused silica,” Appl. Opt. 57(20), 5566–5573 (2018).
    [Crossref]
  16. N. I. Chkhalo, S. A. Churin, M. S. Mikhaylenko, A. E. Pestov, V. N. Polkovnikov, N. N. Salashchenko, and M. V. Zorina, “Ion-beam polishing of fused silica substrates for imaging soft x-ray and extreme ultraviolet optics,” Appl. Opt. 55(6), 1249–1256 (2016).
    [Crossref]
  17. W. L. Liao, Y. F. Dai, and X. H. Xie, “Nanopatterning of optical surfaces during low-energy ion beam sputtering,” Opt. Eng. 53(6), 065108 (2014).
    [Crossref]
  18. C.M. Egert, “Roughness evolution of optical materials induced by ion beam milling,” Proc. SPIE 1752, 63–72 (1992).
    [Crossref]
  19. J. Bauer, F. Frost, and T. Arnold, “Reactive ion beam figuring of optical aluminum surfaces,” J. Phys. D: Appl. Phys. 50(8), 085101 (2017).
    [Crossref]
  20. Y. T. Huang, B. Fan, Y. J. Wan, and S. J. Li, “Improving the performance of single point diamond turning surface with ion beam figuring,” Optik 172, 540–544 (2018).
    [Crossref]
  21. G.P.H Gubbels, B.W.H van Venrooy, A. J. Bosch, and R. Senden, “Rapidly solidified aluminum for optical applications,” Proc. SPIE 7018, 70183A (2008).
    [Crossref]
  22. Y. Gong and L. Zhao, “Single point diamond machine and their applications to optical engineering,” Chin. Opt. 4, 537–545 (2011).
  23. S. Risse, A. Gebhardt, C. Damm, T. Peschel, W. Stockl, T. Feigl, S. Kirschstein, R. Eberhardt, N. Kaiser, and A. Tunnermann, “Novel TMA telescope based on ultra-precise metal mirrors,” Proc. SPIE 7010, 701016 (2008).
    [Crossref]
  24. P. Sigmund, Theory of sputtering. I. “Sputtering yield of amorphous and polycrystalline targets,” Phys. Rev. 184(2), 383–416(1969).
    [Crossref]
  25. T. V. Panova, V. I. Blinov, V. S. Kovivchak, G. I. Gering, and D. V. Konstantinov, “Formation of preferred orientations in Aluminum, Copper, and Nickel Irradiated with Intense Ion Beams,” J. Synch. Investig. 1(2), 197–203 (2007).
    [Crossref]
  26. P. D. Shipman and R. M. Bradley, “Theory of nanoscale pattern formation induced by normal-incidence ion bombardment of binary compounds,” Phys. Rev. B 84(8), 085420 (2011).
    [Crossref]
  27. R. M. Bradley, “Surface instability of binary compounds caused by sputter yield amplification,” Appl. Phys. Rev. 111(11), 114305 (2012).
    [Crossref]
  28. R. M. Bradley and P. D. Shipman, “A surface layer of altered composition can play a key role in nanoscale pattern formation induced by ion bombardment,” Appl. Surf. Sci. 258(9), 4161–4170 (2012).
    [Crossref]
  29. R. M. Bradley, “Nanoscale compositional binding in binary thin films produced by ion-assisted deposition,” J. Appl. Phys. 114(22), 224306 (2013).
    [Crossref]
  30. R. M. Bradley, “Morphological transition in nanoscale patterns produced by concurrent ion sputtering and impurity co-deposition,” J. Appl. Phys. 119(13), 134305 (2016).
    [Crossref]
  31. V. B. Shenoy, W. L. Chan, and E. Chason, “Compositionally modulated ripples induced by sputtering of alloy surfaces,” Phys. Rev. Lett. 98(25), 256101 (2007).
    [Crossref]
  32. S. Sarkar, B. V. Daele, and W. Vandervorst, “Impact of repetitive and random surface morphologies on the ripple formation on ion bombardment SiGe-surfaces,” New J. Phys. 10(8), 083012 (2008).
    [Crossref]
  33. T. M. Mayer, E. Chason, and A. J. Howard, “Roughening instability and ion -induced viscous relaxation of SiO2 surfaces,” J. Appl. Phys. 76(3), 1633–1643 (1994).
    [Crossref]

2018 (3)

2017 (3)

2016 (2)

2015 (2)

L. Wamboldt, B. Roy, J. Crifasi, S. Stephens, D. Hanninen, K. Woodard, R. Felock, S. Polczwartek, and J. Parenteau, “An ultra-low surface finish process for 6061-Al mirrors,” Proc. SPIE 9451, 945111 (2015).
[Crossref]

Z. X. Feng, B. D. Froese, C. Y. Huang, D. L. Ma, and R. G. Liang, “Creating unconventional geometric beams with large depth of field using double freeform-surface optics,” Appl. Opt. 54(20), 6277–6281 (2015).
[Crossref]

2014 (2)

A. Bauer and J. P. Rolland, “Visual space assessment of two all-reflective, freeform, optical see-through head-worn displays,” Opt. Express 22(11), 13155–13163 (2014).
[Crossref]

W. L. Liao, Y. F. Dai, and X. H. Xie, “Nanopatterning of optical surfaces during low-energy ion beam sputtering,” Opt. Eng. 53(6), 065108 (2014).
[Crossref]

2013 (1)

R. M. Bradley, “Nanoscale compositional binding in binary thin films produced by ion-assisted deposition,” J. Appl. Phys. 114(22), 224306 (2013).
[Crossref]

2012 (3)

R. M. Bradley, “Surface instability of binary compounds caused by sputter yield amplification,” Appl. Phys. Rev. 111(11), 114305 (2012).
[Crossref]

R. M. Bradley and P. D. Shipman, “A surface layer of altered composition can play a key role in nanoscale pattern formation induced by ion bombardment,” Appl. Surf. Sci. 258(9), 4161–4170 (2012).
[Crossref]

L. Li and A. Y. Yi, “Design and fabrication of a freeform microlens array for a compact large-field-of-view compound-eye camera,” Appl. Opt. 51(12), 1843–1852 (2012).
[Crossref]

2011 (2)

Y. Gong and L. Zhao, “Single point diamond machine and their applications to optical engineering,” Chin. Opt. 4, 537–545 (2011).

P. D. Shipman and R. M. Bradley, “Theory of nanoscale pattern formation induced by normal-incidence ion bombardment of binary compounds,” Phys. Rev. B 84(8), 085420 (2011).
[Crossref]

2009 (3)

A. Keller, S. Facsko, and W. Moller, “Evolution of ion-induced ripple patterns on SiO2 surfaces,” Nucl. Instrum. Methods Phys. Res., Sect. B 267(4), 656–659 (2009).
[Crossref]

M. Weiser, “Ion beam figuring for lithography optics,” Nucl. Instrum. Methods Phys. Res., Sect. B 267(8-9), 1390–1393 (2009).
[Crossref]

F. Frost, R. Fechner, B. Ziberi, J. Vollner, D. Flamm, and A. Schindler, “Large area smoothing of surfaces by ion bombardment: fundamentals and applications,” J. Phys.: Condens. Matter 21(22), 224026 (2009).
[Crossref]

2008 (3)

S. Sarkar, B. V. Daele, and W. Vandervorst, “Impact of repetitive and random surface morphologies on the ripple formation on ion bombardment SiGe-surfaces,” New J. Phys. 10(8), 083012 (2008).
[Crossref]

S. Risse, A. Gebhardt, C. Damm, T. Peschel, W. Stockl, T. Feigl, S. Kirschstein, R. Eberhardt, N. Kaiser, and A. Tunnermann, “Novel TMA telescope based on ultra-precise metal mirrors,” Proc. SPIE 7010, 701016 (2008).
[Crossref]

G.P.H Gubbels, B.W.H van Venrooy, A. J. Bosch, and R. Senden, “Rapidly solidified aluminum for optical applications,” Proc. SPIE 7018, 70183A (2008).
[Crossref]

2007 (2)

T. V. Panova, V. I. Blinov, V. S. Kovivchak, G. I. Gering, and D. V. Konstantinov, “Formation of preferred orientations in Aluminum, Copper, and Nickel Irradiated with Intense Ion Beams,” J. Synch. Investig. 1(2), 197–203 (2007).
[Crossref]

V. B. Shenoy, W. L. Chan, and E. Chason, “Compositionally modulated ripples induced by sputtering of alloy surfaces,” Phys. Rev. Lett. 98(25), 256101 (2007).
[Crossref]

2004 (1)

Y. Ahn, J. Y. Yoon, C. W. Baek, and Y. K. Kim, “Chemical mechanical polishing by colloidal silica-based slurry for micro-scratch reduction,” Wear 257(7-8), 785–789 (2004).
[Crossref]

2002 (1)

C. C. Wang, S. C. Lin, and H. Hong, “A material removal model for polishing glass-ceramic and aluminum magnesium storage disk,” Int. J. Mach. Tool Manu. 42(8), 979–984 (2002).
[Crossref]

1998 (1)

Y. L. Wang, J. Wu, C. W. Liu, T. C. Wang, and J. W. Dun, “Material characteristics and chemical-mechanical polishing of aluminum alloy thin films,” Thin Solid Films 332(1-2), 397–403 (1998).
[Crossref]

1994 (1)

T. M. Mayer, E. Chason, and A. J. Howard, “Roughening instability and ion -induced viscous relaxation of SiO2 surfaces,” J. Appl. Phys. 76(3), 1633–1643 (1994).
[Crossref]

1992 (1)

C.M. Egert, “Roughness evolution of optical materials induced by ion beam milling,” Proc. SPIE 1752, 63–72 (1992).
[Crossref]

1988 (1)

R. M. Bradley and J. M. E. Harper, “Theory of ripple topography induced by ion bombardment,” J. Vac. Sci. Technol., A 6(4), 2390–2395 (1988).
[Crossref]

1969 (1)

P. Sigmund, Theory of sputtering. I. “Sputtering yield of amorphous and polycrystalline targets,” Phys. Rev. 184(2), 383–416(1969).
[Crossref]

Ahn, Y.

Y. Ahn, J. Y. Yoon, C. W. Baek, and Y. K. Kim, “Chemical mechanical polishing by colloidal silica-based slurry for micro-scratch reduction,” Wear 257(7-8), 785–789 (2004).
[Crossref]

Arnold, T.

J. Bauer, F. Frost, and T. Arnold, “Reactive ion beam figuring of optical aluminum surfaces,” J. Phys. D: Appl. Phys. 50(8), 085101 (2017).
[Crossref]

Baek, C. W.

Y. Ahn, J. Y. Yoon, C. W. Baek, and Y. K. Kim, “Chemical mechanical polishing by colloidal silica-based slurry for micro-scratch reduction,” Wear 257(7-8), 785–789 (2004).
[Crossref]

Bauer, A.

Bauer, J.

J. Bauer, F. Frost, and T. Arnold, “Reactive ion beam figuring of optical aluminum surfaces,” J. Phys. D: Appl. Phys. 50(8), 085101 (2017).
[Crossref]

Blinov, V. I.

T. V. Panova, V. I. Blinov, V. S. Kovivchak, G. I. Gering, and D. V. Konstantinov, “Formation of preferred orientations in Aluminum, Copper, and Nickel Irradiated with Intense Ion Beams,” J. Synch. Investig. 1(2), 197–203 (2007).
[Crossref]

Bosch, A. J.

G.P.H Gubbels, B.W.H van Venrooy, A. J. Bosch, and R. Senden, “Rapidly solidified aluminum for optical applications,” Proc. SPIE 7018, 70183A (2008).
[Crossref]

Bradley, R. M.

R. M. Bradley, “Morphological transition in nanoscale patterns produced by concurrent ion sputtering and impurity co-deposition,” J. Appl. Phys. 119(13), 134305 (2016).
[Crossref]

R. M. Bradley, “Nanoscale compositional binding in binary thin films produced by ion-assisted deposition,” J. Appl. Phys. 114(22), 224306 (2013).
[Crossref]

R. M. Bradley, “Surface instability of binary compounds caused by sputter yield amplification,” Appl. Phys. Rev. 111(11), 114305 (2012).
[Crossref]

R. M. Bradley and P. D. Shipman, “A surface layer of altered composition can play a key role in nanoscale pattern formation induced by ion bombardment,” Appl. Surf. Sci. 258(9), 4161–4170 (2012).
[Crossref]

P. D. Shipman and R. M. Bradley, “Theory of nanoscale pattern formation induced by normal-incidence ion bombardment of binary compounds,” Phys. Rev. B 84(8), 085420 (2011).
[Crossref]

R. M. Bradley and J. M. E. Harper, “Theory of ripple topography induced by ion bombardment,” J. Vac. Sci. Technol., A 6(4), 2390–2395 (1988).
[Crossref]

Chan, W. L.

V. B. Shenoy, W. L. Chan, and E. Chason, “Compositionally modulated ripples induced by sputtering of alloy surfaces,” Phys. Rev. Lett. 98(25), 256101 (2007).
[Crossref]

Chason, E.

V. B. Shenoy, W. L. Chan, and E. Chason, “Compositionally modulated ripples induced by sputtering of alloy surfaces,” Phys. Rev. Lett. 98(25), 256101 (2007).
[Crossref]

T. M. Mayer, E. Chason, and A. J. Howard, “Roughening instability and ion -induced viscous relaxation of SiO2 surfaces,” J. Appl. Phys. 76(3), 1633–1643 (1994).
[Crossref]

Chen, S. S.

Chkhalo, N. I.

Churin, S. A.

Crifasi, J.

L. Wamboldt, B. Roy, J. Crifasi, S. Stephens, D. Hanninen, K. Woodard, R. Felock, S. Polczwartek, and J. Parenteau, “An ultra-low surface finish process for 6061-Al mirrors,” Proc. SPIE 9451, 945111 (2015).
[Crossref]

Daele, B. V.

S. Sarkar, B. V. Daele, and W. Vandervorst, “Impact of repetitive and random surface morphologies on the ripple formation on ion bombardment SiGe-surfaces,” New J. Phys. 10(8), 083012 (2008).
[Crossref]

Dai, Y. F.

M. J. Xu, Y. F. Dai, L. Zhou, X. Q. Peng, S. S. Chen, and W. L. Liao, “Evolution mechanism of surface roughness during ion beam sputtering of fused silica,” Appl. Opt. 57(20), 5566–5573 (2018).
[Crossref]

W. L. Liao, Y. F. Dai, and X. H. Xie, “Nanopatterning of optical surfaces during low-energy ion beam sputtering,” Opt. Eng. 53(6), 065108 (2014).
[Crossref]

Damm, C.

S. Risse, A. Gebhardt, C. Damm, T. Peschel, W. Stockl, T. Feigl, S. Kirschstein, R. Eberhardt, N. Kaiser, and A. Tunnermann, “Novel TMA telescope based on ultra-precise metal mirrors,” Proc. SPIE 7010, 701016 (2008).
[Crossref]

Dun, J. W.

Y. L. Wang, J. Wu, C. W. Liu, T. C. Wang, and J. W. Dun, “Material characteristics and chemical-mechanical polishing of aluminum alloy thin films,” Thin Solid Films 332(1-2), 397–403 (1998).
[Crossref]

Eberhardt, R.

S. Risse, A. Gebhardt, C. Damm, T. Peschel, W. Stockl, T. Feigl, S. Kirschstein, R. Eberhardt, N. Kaiser, and A. Tunnermann, “Novel TMA telescope based on ultra-precise metal mirrors,” Proc. SPIE 7010, 701016 (2008).
[Crossref]

Egert, C.M.

C.M. Egert, “Roughness evolution of optical materials induced by ion beam milling,” Proc. SPIE 1752, 63–72 (1992).
[Crossref]

Facsko, S.

A. Keller, S. Facsko, and W. Moller, “Evolution of ion-induced ripple patterns on SiO2 surfaces,” Nucl. Instrum. Methods Phys. Res., Sect. B 267(4), 656–659 (2009).
[Crossref]

Fan, B.

Y. T. Huang, B. Fan, Y. J. Wan, and S. J. Li, “Improving the performance of single point diamond turning surface with ion beam figuring,” Optik 172, 540–544 (2018).
[Crossref]

Fang, F.

Fechner, R.

F. Frost, R. Fechner, B. Ziberi, J. Vollner, D. Flamm, and A. Schindler, “Large area smoothing of surfaces by ion bombardment: fundamentals and applications,” J. Phys.: Condens. Matter 21(22), 224026 (2009).
[Crossref]

Feigl, T.

S. Risse, A. Gebhardt, C. Damm, T. Peschel, W. Stockl, T. Feigl, S. Kirschstein, R. Eberhardt, N. Kaiser, and A. Tunnermann, “Novel TMA telescope based on ultra-precise metal mirrors,” Proc. SPIE 7010, 701016 (2008).
[Crossref]

Felock, R.

L. Wamboldt, B. Roy, J. Crifasi, S. Stephens, D. Hanninen, K. Woodard, R. Felock, S. Polczwartek, and J. Parenteau, “An ultra-low surface finish process for 6061-Al mirrors,” Proc. SPIE 9451, 945111 (2015).
[Crossref]

Feng, Z. X.

Flamm, D.

F. Frost, R. Fechner, B. Ziberi, J. Vollner, D. Flamm, and A. Schindler, “Large area smoothing of surfaces by ion bombardment: fundamentals and applications,” J. Phys.: Condens. Matter 21(22), 224026 (2009).
[Crossref]

Froese, B. D.

Frost, F.

J. Bauer, F. Frost, and T. Arnold, “Reactive ion beam figuring of optical aluminum surfaces,” J. Phys. D: Appl. Phys. 50(8), 085101 (2017).
[Crossref]

F. Frost, R. Fechner, B. Ziberi, J. Vollner, D. Flamm, and A. Schindler, “Large area smoothing of surfaces by ion bombardment: fundamentals and applications,” J. Phys.: Condens. Matter 21(22), 224026 (2009).
[Crossref]

Gebhardt, A.

S. Risse, A. Gebhardt, C. Damm, T. Peschel, W. Stockl, T. Feigl, S. Kirschstein, R. Eberhardt, N. Kaiser, and A. Tunnermann, “Novel TMA telescope based on ultra-precise metal mirrors,” Proc. SPIE 7010, 701016 (2008).
[Crossref]

Gering, G. I.

T. V. Panova, V. I. Blinov, V. S. Kovivchak, G. I. Gering, and D. V. Konstantinov, “Formation of preferred orientations in Aluminum, Copper, and Nickel Irradiated with Intense Ion Beams,” J. Synch. Investig. 1(2), 197–203 (2007).
[Crossref]

Gong, Y.

Y. Gong and L. Zhao, “Single point diamond machine and their applications to optical engineering,” Chin. Opt. 4, 537–545 (2011).

Gubbels, G.P.H

G.P.H Gubbels, B.W.H van Venrooy, A. J. Bosch, and R. Senden, “Rapidly solidified aluminum for optical applications,” Proc. SPIE 7018, 70183A (2008).
[Crossref]

Hanninen, D.

L. Wamboldt, B. Roy, J. Crifasi, S. Stephens, D. Hanninen, K. Woodard, R. Felock, S. Polczwartek, and J. Parenteau, “An ultra-low surface finish process for 6061-Al mirrors,” Proc. SPIE 9451, 945111 (2015).
[Crossref]

Harper, J. M. E.

R. M. Bradley and J. M. E. Harper, “Theory of ripple topography induced by ion bombardment,” J. Vac. Sci. Technol., A 6(4), 2390–2395 (1988).
[Crossref]

He, Z. P.

Hong, H.

C. C. Wang, S. C. Lin, and H. Hong, “A material removal model for polishing glass-ceramic and aluminum magnesium storage disk,” Int. J. Mach. Tool Manu. 42(8), 979–984 (2002).
[Crossref]

Howard, A. J.

T. M. Mayer, E. Chason, and A. J. Howard, “Roughening instability and ion -induced viscous relaxation of SiO2 surfaces,” J. Appl. Phys. 76(3), 1633–1643 (1994).
[Crossref]

Huang, C. Y.

Huang, Y. T.

Y. T. Huang, B. Fan, Y. J. Wan, and S. J. Li, “Improving the performance of single point diamond turning surface with ion beam figuring,” Optik 172, 540–544 (2018).
[Crossref]

Kaiser, N.

S. Risse, A. Gebhardt, C. Damm, T. Peschel, W. Stockl, T. Feigl, S. Kirschstein, R. Eberhardt, N. Kaiser, and A. Tunnermann, “Novel TMA telescope based on ultra-precise metal mirrors,” Proc. SPIE 7010, 701016 (2008).
[Crossref]

Keller, A.

A. Keller, S. Facsko, and W. Moller, “Evolution of ion-induced ripple patterns on SiO2 surfaces,” Nucl. Instrum. Methods Phys. Res., Sect. B 267(4), 656–659 (2009).
[Crossref]

Kim, Y. K.

Y. Ahn, J. Y. Yoon, C. W. Baek, and Y. K. Kim, “Chemical mechanical polishing by colloidal silica-based slurry for micro-scratch reduction,” Wear 257(7-8), 785–789 (2004).
[Crossref]

Kirschstein, S.

S. Risse, A. Gebhardt, C. Damm, T. Peschel, W. Stockl, T. Feigl, S. Kirschstein, R. Eberhardt, N. Kaiser, and A. Tunnermann, “Novel TMA telescope based on ultra-precise metal mirrors,” Proc. SPIE 7010, 701016 (2008).
[Crossref]

Konstantinov, D. V.

T. V. Panova, V. I. Blinov, V. S. Kovivchak, G. I. Gering, and D. V. Konstantinov, “Formation of preferred orientations in Aluminum, Copper, and Nickel Irradiated with Intense Ion Beams,” J. Synch. Investig. 1(2), 197–203 (2007).
[Crossref]

Kovivchak, V. S.

T. V. Panova, V. I. Blinov, V. S. Kovivchak, G. I. Gering, and D. V. Konstantinov, “Formation of preferred orientations in Aluminum, Copper, and Nickel Irradiated with Intense Ion Beams,” J. Synch. Investig. 1(2), 197–203 (2007).
[Crossref]

Li, C. L.

Li, L.

Li, S. J.

Y. T. Huang, B. Fan, Y. J. Wan, and S. J. Li, “Improving the performance of single point diamond turning surface with ion beam figuring,” Optik 172, 540–544 (2018).
[Crossref]

Li, Z.

Liang, R. G.

Liao, W. L.

M. J. Xu, Y. F. Dai, L. Zhou, X. Q. Peng, S. S. Chen, and W. L. Liao, “Evolution mechanism of surface roughness during ion beam sputtering of fused silica,” Appl. Opt. 57(20), 5566–5573 (2018).
[Crossref]

W. L. Liao, Y. F. Dai, and X. H. Xie, “Nanopatterning of optical surfaces during low-energy ion beam sputtering,” Opt. Eng. 53(6), 065108 (2014).
[Crossref]

Lin, S. C.

C. C. Wang, S. C. Lin, and H. Hong, “A material removal model for polishing glass-ceramic and aluminum magnesium storage disk,” Int. J. Mach. Tool Manu. 42(8), 979–984 (2002).
[Crossref]

Liu, C. W.

Y. L. Wang, J. Wu, C. W. Liu, T. C. Wang, and J. W. Dun, “Material characteristics and chemical-mechanical polishing of aluminum alloy thin films,” Thin Solid Films 332(1-2), 397–403 (1998).
[Crossref]

Liu, X.

Lv, G.

Ma, D. L.

Mayer, T. M.

T. M. Mayer, E. Chason, and A. J. Howard, “Roughening instability and ion -induced viscous relaxation of SiO2 surfaces,” J. Appl. Phys. 76(3), 1633–1643 (1994).
[Crossref]

Mikhaylenko, M. S.

Moller, W.

A. Keller, S. Facsko, and W. Moller, “Evolution of ion-induced ripple patterns on SiO2 surfaces,” Nucl. Instrum. Methods Phys. Res., Sect. B 267(4), 656–659 (2009).
[Crossref]

Panova, T. V.

T. V. Panova, V. I. Blinov, V. S. Kovivchak, G. I. Gering, and D. V. Konstantinov, “Formation of preferred orientations in Aluminum, Copper, and Nickel Irradiated with Intense Ion Beams,” J. Synch. Investig. 1(2), 197–203 (2007).
[Crossref]

Parenteau, J.

L. Wamboldt, B. Roy, J. Crifasi, S. Stephens, D. Hanninen, K. Woodard, R. Felock, S. Polczwartek, and J. Parenteau, “An ultra-low surface finish process for 6061-Al mirrors,” Proc. SPIE 9451, 945111 (2015).
[Crossref]

Peng, X. Q.

Peschel, T.

S. Risse, A. Gebhardt, C. Damm, T. Peschel, W. Stockl, T. Feigl, S. Kirschstein, R. Eberhardt, N. Kaiser, and A. Tunnermann, “Novel TMA telescope based on ultra-precise metal mirrors,” Proc. SPIE 7010, 701016 (2008).
[Crossref]

Pestov, A. E.

Polczwartek, S.

L. Wamboldt, B. Roy, J. Crifasi, S. Stephens, D. Hanninen, K. Woodard, R. Felock, S. Polczwartek, and J. Parenteau, “An ultra-low surface finish process for 6061-Al mirrors,” Proc. SPIE 9451, 945111 (2015).
[Crossref]

Polkovnikov, V. N.

Risse, S.

S. Risse, A. Gebhardt, C. Damm, T. Peschel, W. Stockl, T. Feigl, S. Kirschstein, R. Eberhardt, N. Kaiser, and A. Tunnermann, “Novel TMA telescope based on ultra-precise metal mirrors,” Proc. SPIE 7010, 701016 (2008).
[Crossref]

Rolland, J. P.

Roy, B.

L. Wamboldt, B. Roy, J. Crifasi, S. Stephens, D. Hanninen, K. Woodard, R. Felock, S. Polczwartek, and J. Parenteau, “An ultra-low surface finish process for 6061-Al mirrors,” Proc. SPIE 9451, 945111 (2015).
[Crossref]

Salashchenko, N. N.

Sarkar, S.

S. Sarkar, B. V. Daele, and W. Vandervorst, “Impact of repetitive and random surface morphologies on the ripple formation on ion bombardment SiGe-surfaces,” New J. Phys. 10(8), 083012 (2008).
[Crossref]

Schindler, A.

F. Frost, R. Fechner, B. Ziberi, J. Vollner, D. Flamm, and A. Schindler, “Large area smoothing of surfaces by ion bombardment: fundamentals and applications,” J. Phys.: Condens. Matter 21(22), 224026 (2009).
[Crossref]

Senden, R.

G.P.H Gubbels, B.W.H van Venrooy, A. J. Bosch, and R. Senden, “Rapidly solidified aluminum for optical applications,” Proc. SPIE 7018, 70183A (2008).
[Crossref]

Shenoy, V. B.

V. B. Shenoy, W. L. Chan, and E. Chason, “Compositionally modulated ripples induced by sputtering of alloy surfaces,” Phys. Rev. Lett. 98(25), 256101 (2007).
[Crossref]

Shipman, P. D.

R. M. Bradley and P. D. Shipman, “A surface layer of altered composition can play a key role in nanoscale pattern formation induced by ion bombardment,” Appl. Surf. Sci. 258(9), 4161–4170 (2012).
[Crossref]

P. D. Shipman and R. M. Bradley, “Theory of nanoscale pattern formation induced by normal-incidence ion bombardment of binary compounds,” Phys. Rev. B 84(8), 085420 (2011).
[Crossref]

Sigmund, P.

P. Sigmund, Theory of sputtering. I. “Sputtering yield of amorphous and polycrystalline targets,” Phys. Rev. 184(2), 383–416(1969).
[Crossref]

Stephens, S.

L. Wamboldt, B. Roy, J. Crifasi, S. Stephens, D. Hanninen, K. Woodard, R. Felock, S. Polczwartek, and J. Parenteau, “An ultra-low surface finish process for 6061-Al mirrors,” Proc. SPIE 9451, 945111 (2015).
[Crossref]

Stockl, W.

S. Risse, A. Gebhardt, C. Damm, T. Peschel, W. Stockl, T. Feigl, S. Kirschstein, R. Eberhardt, N. Kaiser, and A. Tunnermann, “Novel TMA telescope based on ultra-precise metal mirrors,” Proc. SPIE 7010, 701016 (2008).
[Crossref]

Tunnermann, A.

S. Risse, A. Gebhardt, C. Damm, T. Peschel, W. Stockl, T. Feigl, S. Kirschstein, R. Eberhardt, N. Kaiser, and A. Tunnermann, “Novel TMA telescope based on ultra-precise metal mirrors,” Proc. SPIE 7010, 701016 (2008).
[Crossref]

van Venrooy, B.W.H

G.P.H Gubbels, B.W.H van Venrooy, A. J. Bosch, and R. Senden, “Rapidly solidified aluminum for optical applications,” Proc. SPIE 7018, 70183A (2008).
[Crossref]

Vandervorst, W.

S. Sarkar, B. V. Daele, and W. Vandervorst, “Impact of repetitive and random surface morphologies on the ripple formation on ion bombardment SiGe-surfaces,” New J. Phys. 10(8), 083012 (2008).
[Crossref]

Vollner, J.

F. Frost, R. Fechner, B. Ziberi, J. Vollner, D. Flamm, and A. Schindler, “Large area smoothing of surfaces by ion bombardment: fundamentals and applications,” J. Phys.: Condens. Matter 21(22), 224026 (2009).
[Crossref]

Wamboldt, L.

L. Wamboldt, B. Roy, J. Crifasi, S. Stephens, D. Hanninen, K. Woodard, R. Felock, S. Polczwartek, and J. Parenteau, “An ultra-low surface finish process for 6061-Al mirrors,” Proc. SPIE 9451, 945111 (2015).
[Crossref]

Wan, Y. J.

Y. T. Huang, B. Fan, Y. J. Wan, and S. J. Li, “Improving the performance of single point diamond turning surface with ion beam figuring,” Optik 172, 540–544 (2018).
[Crossref]

Wang, C. C.

C. C. Wang, S. C. Lin, and H. Hong, “A material removal model for polishing glass-ceramic and aluminum magnesium storage disk,” Int. J. Mach. Tool Manu. 42(8), 979–984 (2002).
[Crossref]

Wang, J. Y.

Wang, T. C.

Y. L. Wang, J. Wu, C. W. Liu, T. C. Wang, and J. W. Dun, “Material characteristics and chemical-mechanical polishing of aluminum alloy thin films,” Thin Solid Films 332(1-2), 397–403 (1998).
[Crossref]

Wang, Y.

Wang, Y. L.

Y. L. Wang, J. Wu, C. W. Liu, T. C. Wang, and J. W. Dun, “Material characteristics and chemical-mechanical polishing of aluminum alloy thin films,” Thin Solid Films 332(1-2), 397–403 (1998).
[Crossref]

Wang, Y. M.

Weiser, M.

M. Weiser, “Ion beam figuring for lithography optics,” Nucl. Instrum. Methods Phys. Res., Sect. B 267(8-9), 1390–1393 (2009).
[Crossref]

Woodard, K.

L. Wamboldt, B. Roy, J. Crifasi, S. Stephens, D. Hanninen, K. Woodard, R. Felock, S. Polczwartek, and J. Parenteau, “An ultra-low surface finish process for 6061-Al mirrors,” Proc. SPIE 9451, 945111 (2015).
[Crossref]

Wu, J.

Y. L. Wang, J. Wu, C. W. Liu, T. C. Wang, and J. W. Dun, “Material characteristics and chemical-mechanical polishing of aluminum alloy thin films,” Thin Solid Films 332(1-2), 397–403 (1998).
[Crossref]

Xie, J. N.

Xie, X. H.

W. L. Liao, Y. F. Dai, and X. H. Xie, “Nanopatterning of optical surfaces during low-energy ion beam sputtering,” Opt. Eng. 53(6), 065108 (2014).
[Crossref]

Xu, M. J.

Yi, A. Y.

Yoon, J. Y.

Y. Ahn, J. Y. Yoon, C. W. Baek, and Y. K. Kim, “Chemical mechanical polishing by colloidal silica-based slurry for micro-scratch reduction,” Wear 257(7-8), 785–789 (2004).
[Crossref]

Yuan, L. Y.

Zhang, X.

Zhao, L.

Y. Gong and L. Zhao, “Single point diamond machine and their applications to optical engineering,” Chin. Opt. 4, 537–545 (2011).

Zhou, L.

Ziberi, B.

F. Frost, R. Fechner, B. Ziberi, J. Vollner, D. Flamm, and A. Schindler, “Large area smoothing of surfaces by ion bombardment: fundamentals and applications,” J. Phys.: Condens. Matter 21(22), 224026 (2009).
[Crossref]

Zorina, M. V.

Appl. Opt. (5)

Appl. Phys. Rev. (1)

R. M. Bradley, “Surface instability of binary compounds caused by sputter yield amplification,” Appl. Phys. Rev. 111(11), 114305 (2012).
[Crossref]

Appl. Surf. Sci. (1)

R. M. Bradley and P. D. Shipman, “A surface layer of altered composition can play a key role in nanoscale pattern formation induced by ion bombardment,” Appl. Surf. Sci. 258(9), 4161–4170 (2012).
[Crossref]

Chin. Opt. (1)

Y. Gong and L. Zhao, “Single point diamond machine and their applications to optical engineering,” Chin. Opt. 4, 537–545 (2011).

Int. J. Mach. Tool Manu. (1)

C. C. Wang, S. C. Lin, and H. Hong, “A material removal model for polishing glass-ceramic and aluminum magnesium storage disk,” Int. J. Mach. Tool Manu. 42(8), 979–984 (2002).
[Crossref]

J. Appl. Phys. (3)

R. M. Bradley, “Nanoscale compositional binding in binary thin films produced by ion-assisted deposition,” J. Appl. Phys. 114(22), 224306 (2013).
[Crossref]

R. M. Bradley, “Morphological transition in nanoscale patterns produced by concurrent ion sputtering and impurity co-deposition,” J. Appl. Phys. 119(13), 134305 (2016).
[Crossref]

T. M. Mayer, E. Chason, and A. J. Howard, “Roughening instability and ion -induced viscous relaxation of SiO2 surfaces,” J. Appl. Phys. 76(3), 1633–1643 (1994).
[Crossref]

J. Phys. D: Appl. Phys. (1)

J. Bauer, F. Frost, and T. Arnold, “Reactive ion beam figuring of optical aluminum surfaces,” J. Phys. D: Appl. Phys. 50(8), 085101 (2017).
[Crossref]

J. Phys.: Condens. Matter (1)

F. Frost, R. Fechner, B. Ziberi, J. Vollner, D. Flamm, and A. Schindler, “Large area smoothing of surfaces by ion bombardment: fundamentals and applications,” J. Phys.: Condens. Matter 21(22), 224026 (2009).
[Crossref]

J. Synch. Investig. (1)

T. V. Panova, V. I. Blinov, V. S. Kovivchak, G. I. Gering, and D. V. Konstantinov, “Formation of preferred orientations in Aluminum, Copper, and Nickel Irradiated with Intense Ion Beams,” J. Synch. Investig. 1(2), 197–203 (2007).
[Crossref]

J. Vac. Sci. Technol., A (1)

R. M. Bradley and J. M. E. Harper, “Theory of ripple topography induced by ion bombardment,” J. Vac. Sci. Technol., A 6(4), 2390–2395 (1988).
[Crossref]

New J. Phys. (1)

S. Sarkar, B. V. Daele, and W. Vandervorst, “Impact of repetitive and random surface morphologies on the ripple formation on ion bombardment SiGe-surfaces,” New J. Phys. 10(8), 083012 (2008).
[Crossref]

Nucl. Instrum. Methods Phys. Res., Sect. B (2)

A. Keller, S. Facsko, and W. Moller, “Evolution of ion-induced ripple patterns on SiO2 surfaces,” Nucl. Instrum. Methods Phys. Res., Sect. B 267(4), 656–659 (2009).
[Crossref]

M. Weiser, “Ion beam figuring for lithography optics,” Nucl. Instrum. Methods Phys. Res., Sect. B 267(8-9), 1390–1393 (2009).
[Crossref]

Opt. Eng. (1)

W. L. Liao, Y. F. Dai, and X. H. Xie, “Nanopatterning of optical surfaces during low-energy ion beam sputtering,” Opt. Eng. 53(6), 065108 (2014).
[Crossref]

Opt. Express (3)

Optik (1)

Y. T. Huang, B. Fan, Y. J. Wan, and S. J. Li, “Improving the performance of single point diamond turning surface with ion beam figuring,” Optik 172, 540–544 (2018).
[Crossref]

Phys. Rev. (1)

P. Sigmund, Theory of sputtering. I. “Sputtering yield of amorphous and polycrystalline targets,” Phys. Rev. 184(2), 383–416(1969).
[Crossref]

Phys. Rev. B (1)

P. D. Shipman and R. M. Bradley, “Theory of nanoscale pattern formation induced by normal-incidence ion bombardment of binary compounds,” Phys. Rev. B 84(8), 085420 (2011).
[Crossref]

Phys. Rev. Lett. (1)

V. B. Shenoy, W. L. Chan, and E. Chason, “Compositionally modulated ripples induced by sputtering of alloy surfaces,” Phys. Rev. Lett. 98(25), 256101 (2007).
[Crossref]

Proc. SPIE (4)

G.P.H Gubbels, B.W.H van Venrooy, A. J. Bosch, and R. Senden, “Rapidly solidified aluminum for optical applications,” Proc. SPIE 7018, 70183A (2008).
[Crossref]

S. Risse, A. Gebhardt, C. Damm, T. Peschel, W. Stockl, T. Feigl, S. Kirschstein, R. Eberhardt, N. Kaiser, and A. Tunnermann, “Novel TMA telescope based on ultra-precise metal mirrors,” Proc. SPIE 7010, 701016 (2008).
[Crossref]

L. Wamboldt, B. Roy, J. Crifasi, S. Stephens, D. Hanninen, K. Woodard, R. Felock, S. Polczwartek, and J. Parenteau, “An ultra-low surface finish process for 6061-Al mirrors,” Proc. SPIE 9451, 945111 (2015).
[Crossref]

C.M. Egert, “Roughness evolution of optical materials induced by ion beam milling,” Proc. SPIE 1752, 63–72 (1992).
[Crossref]

Thin Solid Films (1)

Y. L. Wang, J. Wu, C. W. Liu, T. C. Wang, and J. W. Dun, “Material characteristics and chemical-mechanical polishing of aluminum alloy thin films,” Thin Solid Films 332(1-2), 397–403 (1998).
[Crossref]

Wear (1)

Y. Ahn, J. Y. Yoon, C. W. Baek, and Y. K. Kim, “Chemical mechanical polishing by colloidal silica-based slurry for micro-scratch reduction,” Wear 257(7-8), 785–789 (2004).
[Crossref]

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Figures (14)

Fig. 1.
Fig. 1. IBS trench etching method
Fig. 2.
Fig. 2. Data fitting of roughness with different removal depth (Sample A)
Fig. 3.
Fig. 3. Surface morphology and roughness evolution with different IBS removal depths (sample A). (a)original surface. (b) IBS removal 50 nm. (c) IBS removal 65 nm. (d) IBS removal 100 nm. (e) IBS removal 170 nm. (f) IBS removal 400 nm.
Fig. 4.
Fig. 4. Data fitting of roughness with different removal depth (a) at different voltages while the current maintains 10 mA (Sample B), and (b) at different currents while the voltage maintains 700 eV (Sample C).
Fig. 5.
Fig. 5. SEM, EDS tests after IBS (a) Microscope images, (b) SEM amplifying image of region frames, (c) EDS test of area 1, (d) EDS test of area 2
Fig. 6.
Fig. 6. Morphology evolution of second phase different IBS removal depths and corresponding 3D topography. (a)(d) original surface, (b)(e) IBS removal 40 nm, (c)(f) IBS removal 80 nm.
Fig. 7.
Fig. 7. Morphology evolution of turning marks. (a) original surface, (b) IBS removal 40 nm, (c) IBS removal 80 nm, (d) IBS removal 120 nm.
Fig. 8.
Fig. 8. the corresponding line profiles of WLI images in Fig. 7.
Fig. 9.
Fig. 9. PSD analysis with different removal depth corresponding to Fig. 7.
Fig. 10.
Fig. 10. Morphology evolution of second phase
Fig. 11.
Fig. 11. Morphology evolution of turning marks
Fig. 12.
Fig. 12. grain sputtering state (a)surface planform view, (b) sectional view of line L
Fig. 13.
Fig. 13. Ra deterioration rate as a function of k at different n values
Fig. 14.
Fig. 14. Data fitting of roughness with different removal depth, (a) roughness evolution of 6061-2, (b) comparison of 6061-1 and 6061-2 at range of 0∼1000 nm.

Tables (4)

Tables Icon

Table 1. Parameters of SPDT process

Tables Icon

Table 2. Composition of aluminum alloy

Tables Icon

Table 3. Parameters of IBS process

Tables Icon

Table 4. Parameters of IBS process

Equations (14)

Equations on this page are rendered with MathJax. Learn more.

R a = 1 l 0 l | y ( x ) | d x ,
V = i = 1 n C i v i ,
R a = t i = 1 n C i | V i V | ,
R a = 2 t i = 1 k C i ( V i V ) ,
R a = 2 t n 2 [ ( n k ) i = 1 k V i k j = k + 1 n V j ] = 2 t n 2 ( n k ) k ( V ¯ i V ¯ j ) .
F = F 0 + α 2 h ,
Y i = Λ i F i c i J ,
J i = D i n s c i + D i c i n s Ω γ s k B T 2 h μ i h ,
h t = Ω i = 1 n ( F i + J i ) ,
h t = A + B 2 h + C 2 2 h ,
A = Ω F 0 J ( i = 1 n c i Λ i ) ,
B = Ω ( J α i = 1 n c i Λ i i = 1 n μ i ) ,
C = n s Ω 2 r s k B T ( i = 1 n D i c i ) ,
P S D h ( q , t ) = P S D ( q , t = 0 ) exp ( 2 C ( q ) t ) .

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