Abstract

Ablation of silicon and metals is investigated using a 1064 nm pulsed fiber laser, with pulse energy up to 0.5 mJ, peak powers up to 10 kW, and pulse widths from 10 to 250 ns. A simple thermal model is employed to explain the dependence of scribe depth and shape on pulse energy or peak power. We demonstrate that pulses of high peak powers have shallow penetration depths, while longer pulses with lower peak powers have a higher material removal rate with deeper scribes. The key parameter that enables such variation of performance with changes in peak pulse power or peak irradiance on the material surface is the nonlinear increase of the absorption coefficient of silicon or metals as its temperature increases.

© 2010 OSA

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. J. C. Miller, and R. F. Hagland, Jr., eds., “Laser Ablation and Desorption,” Academic Press, San Diego, CA (1998).
  2. R. E. Russo, “Laser Ablation,” Focal Point 46(9), 14A (1995).
  3. F. John, Ready, “Effects of High-Power Laser Radiation”, pp 79 (Academic Press, 1971).
  4. D. Breitling, A. Ruf, and F. Dausinger, “Fundamental aspects in machining of metals with short and ultrashort laser pulses,” Proc. SPIE 5339, 49–61 (2004).
    [CrossRef]
  5. X. Zeng, X. I. Mao, R. Greif, and R. Russo, “Experimental investigation of ablation efficiency and plasma expansion during femtosecond and nanosecond laser ablation of silicon,” Appl. Phys., A Mater. Sci. Process. 80(2), 237–241 (2005).
    [CrossRef]
  6. H. Herfurth, R. Patwa, T. Lauterborn, S. Heinemann, and H. Pantsar, “Micromachining with tailored Nanosecond Pulses,” in Proceedings of SPIE 6796, 67961G–1 (2007).
  7. J. König, S. Nolte, and A. Tünnermann, “Plasma evolution during metal ablation with ultrashort laser pulses,” Opt. Express 13(26), 10597–10607 (2005).
    [CrossRef] [PubMed]
  8. A. Schoonderbeek, C. A. Biesheuvel, R. M. Hofstra, K.-J. Boller, and J. Meijer, “The influence of the pulse length on the drilling of metals with an excimer laser,” J. Laser Appl. 16(2), 85–91 (2004).
    [CrossRef]
  9. P. Deladurantaye, D. Gay, A. Cournoyer, V. Roy, B. Labranche, M. Levesque, and Y. Taillon, “Material micromachining using a pulsed fiber laser platform with fine temporal nanosecond pulse shaping capability,” in Proceedings of SPIE 7195, 71951S–1 (2009).
  10. S. T. Hendow, J. Sousa, N. Schilling, and J. Rabe, “Pulsed MOPA Fiber Laser Optimized for Processing Silicon and Thin-Film Materials,” 5th Int. Workshop on Fiber Lasers, Dresden, Germany, Sept. 30-Oct.1, 2009.
  11. S.T. Hendow, S.A. Shakir, and J.M. Sousa, “MOPA fiber laser with controlled pulse width and peak power for optimizing micromachining applications,” Photonics West 2010, Paper 7584–42, January 27, 2010.
  12. J. Paul Chernek and Jay A Orson, “A simple thermal response model for a p-doped silicon substrate irradiated by 1.06 and 1.32 micron lasers,” Laser-Induced Damage in Optical Materials, Proc. SPIE 4679, 186 (2002).
    [CrossRef]
  13. D. E. Ackley, A. P. De Fonzo, and J. Tauc, “Optical Absorption Below the Gap in Crystalline and Amorphous Silicon at High Temperatures,” Physics of Semiconductors: Proceedings of the 13th International Conference, Rome, 1976.
  14. K. Dieter Schroder, “Semiconductor Material and Device Characterization,” Third Edition, pp 613, IEEE Press, John Wiley & Sons Inc. 2006.
  15. A. Ganino, Korn and Theresa M. Korn, “Mathematical Handbook for Scientists and Engineers,” pp. 119 (Dover Edition, 2000).
  16. B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).
    [CrossRef]
  17. P. P. Pronko, S. K. Dutta, D. Du, and R. K. Singh, “Thermophysical effects in laser processing of materials with picosecond and femtosecond pulses,” J. Appl. Phys. 78(10), 6233 (1995).
    [CrossRef]

2005 (3)

X. Zeng, X. I. Mao, R. Greif, and R. Russo, “Experimental investigation of ablation efficiency and plasma expansion during femtosecond and nanosecond laser ablation of silicon,” Appl. Phys., A Mater. Sci. Process. 80(2), 237–241 (2005).
[CrossRef]

J. König, S. Nolte, and A. Tünnermann, “Plasma evolution during metal ablation with ultrashort laser pulses,” Opt. Express 13(26), 10597–10607 (2005).
[CrossRef] [PubMed]

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).
[CrossRef]

2004 (2)

D. Breitling, A. Ruf, and F. Dausinger, “Fundamental aspects in machining of metals with short and ultrashort laser pulses,” Proc. SPIE 5339, 49–61 (2004).
[CrossRef]

A. Schoonderbeek, C. A. Biesheuvel, R. M. Hofstra, K.-J. Boller, and J. Meijer, “The influence of the pulse length on the drilling of metals with an excimer laser,” J. Laser Appl. 16(2), 85–91 (2004).
[CrossRef]

2002 (1)

J. Paul Chernek and Jay A Orson, “A simple thermal response model for a p-doped silicon substrate irradiated by 1.06 and 1.32 micron lasers,” Laser-Induced Damage in Optical Materials, Proc. SPIE 4679, 186 (2002).
[CrossRef]

1995 (2)

R. E. Russo, “Laser Ablation,” Focal Point 46(9), 14A (1995).

P. P. Pronko, S. K. Dutta, D. Du, and R. K. Singh, “Thermophysical effects in laser processing of materials with picosecond and femtosecond pulses,” J. Appl. Phys. 78(10), 6233 (1995).
[CrossRef]

Biesheuvel, C. A.

A. Schoonderbeek, C. A. Biesheuvel, R. M. Hofstra, K.-J. Boller, and J. Meijer, “The influence of the pulse length on the drilling of metals with an excimer laser,” J. Laser Appl. 16(2), 85–91 (2004).
[CrossRef]

Boller, K.-J.

A. Schoonderbeek, C. A. Biesheuvel, R. M. Hofstra, K.-J. Boller, and J. Meijer, “The influence of the pulse length on the drilling of metals with an excimer laser,” J. Laser Appl. 16(2), 85–91 (2004).
[CrossRef]

Breitling, D.

D. Breitling, A. Ruf, and F. Dausinger, “Fundamental aspects in machining of metals with short and ultrashort laser pulses,” Proc. SPIE 5339, 49–61 (2004).
[CrossRef]

Chernek, J. Paul

J. Paul Chernek and Jay A Orson, “A simple thermal response model for a p-doped silicon substrate irradiated by 1.06 and 1.32 micron lasers,” Laser-Induced Damage in Optical Materials, Proc. SPIE 4679, 186 (2002).
[CrossRef]

Dausinger, F.

D. Breitling, A. Ruf, and F. Dausinger, “Fundamental aspects in machining of metals with short and ultrashort laser pulses,” Proc. SPIE 5339, 49–61 (2004).
[CrossRef]

Du, D.

P. P. Pronko, S. K. Dutta, D. Du, and R. K. Singh, “Thermophysical effects in laser processing of materials with picosecond and femtosecond pulses,” J. Appl. Phys. 78(10), 6233 (1995).
[CrossRef]

Dutta, S. K.

P. P. Pronko, S. K. Dutta, D. Du, and R. K. Singh, “Thermophysical effects in laser processing of materials with picosecond and femtosecond pulses,” J. Appl. Phys. 78(10), 6233 (1995).
[CrossRef]

Gamaly, E. G.

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).
[CrossRef]

Greif, R.

X. Zeng, X. I. Mao, R. Greif, and R. Russo, “Experimental investigation of ablation efficiency and plasma expansion during femtosecond and nanosecond laser ablation of silicon,” Appl. Phys., A Mater. Sci. Process. 80(2), 237–241 (2005).
[CrossRef]

Hofstra, R. M.

A. Schoonderbeek, C. A. Biesheuvel, R. M. Hofstra, K.-J. Boller, and J. Meijer, “The influence of the pulse length on the drilling of metals with an excimer laser,” J. Laser Appl. 16(2), 85–91 (2004).
[CrossRef]

König, J.

Luther-Davies, B.

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).
[CrossRef]

Madsen, N. R.

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).
[CrossRef]

Mao, X. I.

X. Zeng, X. I. Mao, R. Greif, and R. Russo, “Experimental investigation of ablation efficiency and plasma expansion during femtosecond and nanosecond laser ablation of silicon,” Appl. Phys., A Mater. Sci. Process. 80(2), 237–241 (2005).
[CrossRef]

Meijer, J.

A. Schoonderbeek, C. A. Biesheuvel, R. M. Hofstra, K.-J. Boller, and J. Meijer, “The influence of the pulse length on the drilling of metals with an excimer laser,” J. Laser Appl. 16(2), 85–91 (2004).
[CrossRef]

Nolte, S.

Orson, Jay A

J. Paul Chernek and Jay A Orson, “A simple thermal response model for a p-doped silicon substrate irradiated by 1.06 and 1.32 micron lasers,” Laser-Induced Damage in Optical Materials, Proc. SPIE 4679, 186 (2002).
[CrossRef]

Pronko, P. P.

P. P. Pronko, S. K. Dutta, D. Du, and R. K. Singh, “Thermophysical effects in laser processing of materials with picosecond and femtosecond pulses,” J. Appl. Phys. 78(10), 6233 (1995).
[CrossRef]

Rode, A. V.

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).
[CrossRef]

Ruf, A.

D. Breitling, A. Ruf, and F. Dausinger, “Fundamental aspects in machining of metals with short and ultrashort laser pulses,” Proc. SPIE 5339, 49–61 (2004).
[CrossRef]

Russo, R.

X. Zeng, X. I. Mao, R. Greif, and R. Russo, “Experimental investigation of ablation efficiency and plasma expansion during femtosecond and nanosecond laser ablation of silicon,” Appl. Phys., A Mater. Sci. Process. 80(2), 237–241 (2005).
[CrossRef]

Russo, R. E.

R. E. Russo, “Laser Ablation,” Focal Point 46(9), 14A (1995).

Schoonderbeek, A.

A. Schoonderbeek, C. A. Biesheuvel, R. M. Hofstra, K.-J. Boller, and J. Meijer, “The influence of the pulse length on the drilling of metals with an excimer laser,” J. Laser Appl. 16(2), 85–91 (2004).
[CrossRef]

Singh, R. K.

P. P. Pronko, S. K. Dutta, D. Du, and R. K. Singh, “Thermophysical effects in laser processing of materials with picosecond and femtosecond pulses,” J. Appl. Phys. 78(10), 6233 (1995).
[CrossRef]

Tünnermann, A.

Zeng, X.

X. Zeng, X. I. Mao, R. Greif, and R. Russo, “Experimental investigation of ablation efficiency and plasma expansion during femtosecond and nanosecond laser ablation of silicon,” Appl. Phys., A Mater. Sci. Process. 80(2), 237–241 (2005).
[CrossRef]

Appl. Phys., A Mater. Sci. Process. (1)

X. Zeng, X. I. Mao, R. Greif, and R. Russo, “Experimental investigation of ablation efficiency and plasma expansion during femtosecond and nanosecond laser ablation of silicon,” Appl. Phys., A Mater. Sci. Process. 80(2), 237–241 (2005).
[CrossRef]

Focal Point (1)

R. E. Russo, “Laser Ablation,” Focal Point 46(9), 14A (1995).

J. Appl. Phys. (1)

P. P. Pronko, S. K. Dutta, D. Du, and R. K. Singh, “Thermophysical effects in laser processing of materials with picosecond and femtosecond pulses,” J. Appl. Phys. 78(10), 6233 (1995).
[CrossRef]

J. Laser Appl. (1)

A. Schoonderbeek, C. A. Biesheuvel, R. M. Hofstra, K.-J. Boller, and J. Meijer, “The influence of the pulse length on the drilling of metals with an excimer laser,” J. Laser Appl. 16(2), 85–91 (2004).
[CrossRef]

Opt. Eng. (1)

B. Luther-Davies, A. V. Rode, N. R. Madsen, and E. G. Gamaly, “Picosecond high-repition-rate pulsed laser ablation of dielectrics: the effect of energy accumulation between pulses,” Opt. Eng. 44(5), 051102 (2005).
[CrossRef]

Opt. Express (1)

Proc. SPIE (2)

J. Paul Chernek and Jay A Orson, “A simple thermal response model for a p-doped silicon substrate irradiated by 1.06 and 1.32 micron lasers,” Laser-Induced Damage in Optical Materials, Proc. SPIE 4679, 186 (2002).
[CrossRef]

D. Breitling, A. Ruf, and F. Dausinger, “Fundamental aspects in machining of metals with short and ultrashort laser pulses,” Proc. SPIE 5339, 49–61 (2004).
[CrossRef]

Other (9)

J. C. Miller, and R. F. Hagland, Jr., eds., “Laser Ablation and Desorption,” Academic Press, San Diego, CA (1998).

F. John, Ready, “Effects of High-Power Laser Radiation”, pp 79 (Academic Press, 1971).

P. Deladurantaye, D. Gay, A. Cournoyer, V. Roy, B. Labranche, M. Levesque, and Y. Taillon, “Material micromachining using a pulsed fiber laser platform with fine temporal nanosecond pulse shaping capability,” in Proceedings of SPIE 7195, 71951S–1 (2009).

S. T. Hendow, J. Sousa, N. Schilling, and J. Rabe, “Pulsed MOPA Fiber Laser Optimized for Processing Silicon and Thin-Film Materials,” 5th Int. Workshop on Fiber Lasers, Dresden, Germany, Sept. 30-Oct.1, 2009.

S.T. Hendow, S.A. Shakir, and J.M. Sousa, “MOPA fiber laser with controlled pulse width and peak power for optimizing micromachining applications,” Photonics West 2010, Paper 7584–42, January 27, 2010.

D. E. Ackley, A. P. De Fonzo, and J. Tauc, “Optical Absorption Below the Gap in Crystalline and Amorphous Silicon at High Temperatures,” Physics of Semiconductors: Proceedings of the 13th International Conference, Rome, 1976.

K. Dieter Schroder, “Semiconductor Material and Device Characterization,” Third Edition, pp 613, IEEE Press, John Wiley & Sons Inc. 2006.

A. Ganino, Korn and Theresa M. Korn, “Mathematical Handbook for Scientists and Engineers,” pp. 119 (Dover Edition, 2000).

H. Herfurth, R. Patwa, T. Lauterborn, S. Heinemann, and H. Pantsar, “Micromachining with tailored Nanosecond Pulses,” in Proceedings of SPIE 6796, 67961G–1 (2007).

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (10)

Fig. 1
Fig. 1

(a) Schematic of the fiber laser used in these experiments. The seed laser and amplifier chain is controlled to form pulses of preconfigured peak power and energy. (b) Power distribution of the delivered beam to target. The M2 for this beam is 1.15 and is measured to be constant throughout the experiment. (c) MOPA-M-1μm-10W laser used in this experiment.

Fig. 2
Fig. 2

Schematic of the marking system used to deliver the laser’s output to target. The focused spot is about 20 μm in diameter and has a calculated Rayleigh Range of 300 μm. The beam is focused at the top surface of the work piece.

Fig. 3
Fig. 3

The laser of Fig. 1 was operated at pulse widths of 11.6, 20, 31.6, 50.6, 98.6, 150.5, 201.5 and 243 ns, while its pulse energy is maintained at about 120 μJ. These measurements correspond to average power of 12 W and pulse repetition frequency (PRF) of 100 kHz. These pulse widths are simply referred to in this paper as 10, 20, 30, 50, 100, 150, 200 and 250 ns. The figure on the right shows the corresponding shape of these pulses at 100 kHz. The 250 ns pulse shape is not shown, although the 200 and 250 ns pulses are quite similar in shape. The 75 ns pulse is included for reference only.

Fig. 4
Fig. 4

Successive lines are scribed on the surface using 10 W average power, but with different pulse widths ranging from 10 to 250 ns. The system was operated at constant pulse energy (100 μJ) and 20 μm spot diameter at the silicon surface. PRF is 100 kHz, scan rate is 1 m/sec, and pulse overlap is 66%. The SEM photos shown here are for scribed multi-crystalline silicon using pulse widths of 10, 30, 50, 150 and 200 ns, respectively.

Fig. 5
Fig. 5

The surface temperature distribution of the silicon material as a function of radial distance for various incident pulse widths, 10 to 250 ns. Pulse energy is 100 μJ for all pulses. 10 ns pulses have 10 kW peak powers, while longer pulses have proportionately lower peak powers, as shown in Fig. 3. Note that this temperature rise, which is due to the absorption of a single incident pulse is significantly higher than the boiling temperature of silicon.

Fig. 6
Fig. 6

Temperature rise of aluminum vs. sample’s depth for different incoming pulse widths. The horizontal black line represents boiling temperature of aluminum. The intersection of the curves with the boiling temperature line represents the ablation depth.

Fig. 7
Fig. 7

Ablation depth vs. pulse width for a single trace (solid curve) and measured depths (diamonds) for aluminum. Pulse energy is held constant at 100 μJ and beam diameter is 20 μm. Pulses are 10 μm apart. The error bars on the experimental measurements are ± 1 μm, which corresponds to the surface roughness and irregularity of the bottom of the trench. This irregularity is due to filamentation and recasting of the liquid aluminum.

Fig. 8
Fig. 8

Ablation pit diameter vs. pulse width as defined by Eq. (5) (solid red curve) and measured diameter (blue x and diamond) for aluminum (on the left) and crystalline silicon (right). .The error bars on the experimental measurements are ± 1.5 μm, corresponding to the surface roughness and irregularity at the bottom of the pit. This roughness, measured by a non-contact optical surface profiler, is due to filamentation and recasting of the liquid silicon as it is ejected.

Fig. 9
Fig. 9

(a) Surface profile measurement of an ablation channel formed on multi-crystalline silicon sample using 150 ns pulses, and (b) A quadratic curve fit to the depth profile (blue x) according to Eq. (4) (red curve) and a Gaussian curve fit (dotted brown curve).

Fig. 10
Fig. 10

Ablation pit’s depth vs. pulse width for mono-crystalline silicon. The error bars on the experimental measurements are estimated to be ± 0.5 μm, corresponding to the surface roughness at the bottom, as well as the resolution of the detection microscope.

Equations (8)

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

ΔT(r,z,τ)=ImaxγκπK0τp(τt)t[1+8κtW2]e[z24κt+r24κt+0.5W2]dt
abf(t)dt=f(tc)(ba)
h(r)=4βκτln{βKΔTBγImaxπκβτ(1+8βκτW2}r21+W28βκτh(0)
hscan(r)=h(r)+h(Sr)
ro=(4κto+0.5W2)ln{βKΔTBγImaxπκτ(1+8κβτW2)}
α(T)=αo(T/To)4
K(T)=1585/T1.23(Wcm·K)
κ(T)=15852T1.23+2.54T0.233.68x104T0.77(cm2/s)

Metrics