Abstract

In this research, the plasma etching mechanism which is applied to deposit AlF3 thin films has been discussed in detail. Different ratios of O2 gas were injected in the sputtering process and then the optical properties and microstructure of the thin films were examined. The best optical quality and smallest surface roughness was obtained when the AlF3 thin films were coated with O2:CF4 (12sccm:60sccm) at 30W sputtering power. To increase the deposition rate for industrial application, the sputtering power was increased to 200W with the best ratio of O2/CF4 gas. The results show that the deposition rate at 200W sputtering power was 7.43 times faster than that at 30W sputtering power and the extinction coefficients deposited at 200W are less than 6.8×10-4 at the wavelength range from 190nm to 700nm. To compare the deposition with only CF4 gas at 200W sputtering power, the extinction coefficient of the thin films improve from 4.4×10-3 to 6×10-4 at the wavelength of 193nm. In addition, the structure of the film deposited at 200W was amorphous-like with a surface roughness of 0.8nm.

© 2008 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. C. C. Lee, M.C. Liu, M. Kaneko, K. Nakahira, and Y. Takano, �??Characterization of AlF3 thin films at 193nm by thermal evaporation,�?? Appl. Opt. 44, 7333-7338 (2005).
    [CrossRef] [PubMed]
  2. S. Niisaka, T. Saito, J. Saito, A. Tanaka, A. Matsumoto, M. Otani, R. Biro, C. Ouchi, M. Hasegawa, Y. Suzuki, and K. Sone, �??Development of optical coatings for 157-nm lithography I coating materials,�?? Appl. Opt. 41, 3242-3247 (2002).
    [CrossRef] [PubMed]
  3. O. R. Wood II, H. G. Craighead, J. E. Sweeney, and P. J. Maloney, "Vacuum ultraviolet loss in magnesium fluoride films," Appl. Opt. 23, 3644-3649 (1984).
    [CrossRef]
  4. F. Rainer, W. H. Lowdermilk, D. Milam, C. K. Carniglia, T Tuttle Hart, and T. L. Lichtenstein, "Materials for optical coatings in the ultraviolet," Appl. Opt. 24, 496-500 (1985).
    [CrossRef] [PubMed]
  5. Y. Taki, "Film structure and optical constants of magnetron-sputtered fluoride films for deep ultraviolet lithography," Vacuum 74, 431-435 (2004).
    [CrossRef]
  6. B. H. Liao, M. C. Liu, and C. C. Lee, "A New Process for the Deposition of AlF3 Thin Films," Appl. Opt. 47, C41-C45 (2008).
    [CrossRef] [PubMed]
  7. C. C. Lee, B. H. Liao, and M. C. Liu, "AlF3 thin films deposited by reactive magnetron sputtering with Al target," Opt. Express 15, 9152-9156 (2007).
    [CrossRef] [PubMed]
  8. A. Zuber, N. Kaiser, and J.L. Stehle, "Variable-angle spectroscopic ellipsometry for deep UV characterization of dielectric coating," Thin Solid Films 261, 37-43 (1995).
    [CrossRef]
  9. M. J. Kushner, "A kinetic study of plasma-etching process. I. A model for the etching of Si and SiO2 in CnFm/H2 and CnFm/O2 plasmas," J. Appl. Phys. 53, 2923-2938 (1982).
    [CrossRef]
  10. K. Iwase, P. C. Selvin, G. Sato, and T. Fujii, "Mass spectrometric studies of ionic products in CF4/He and CF4/O2/He microwave discharge plasmas," J. Phys. D: Appl. Phys. 35, 1934-1938 (2002).
    [CrossRef]
  11. M. C. Liu, C. C. Lee, M. Kaneko, K. Nakahira, and Y. Takano, "Microstructure related properties at 193nm of MgF2 and GdF3 films deposited by resistive heating boat," Appl. Opt. 45, 1368-1374 (2006).
    [CrossRef] [PubMed]
  12. M. C. Liu, C. C. Lee, M. Kaneko, K. Nakahira, and Y. Takano, "Microstructure related properties of Lanthanum Fluoride Films Deposited by Molybdenum Boat Evaporation at 193 nm," Thin Solid Films 492/1-2, 45-51 (2005).
    [CrossRef]

2008 (1)

2007 (1)

2006 (1)

2005 (2)

M. C. Liu, C. C. Lee, M. Kaneko, K. Nakahira, and Y. Takano, "Microstructure related properties of Lanthanum Fluoride Films Deposited by Molybdenum Boat Evaporation at 193 nm," Thin Solid Films 492/1-2, 45-51 (2005).
[CrossRef]

C. C. Lee, M.C. Liu, M. Kaneko, K. Nakahira, and Y. Takano, �??Characterization of AlF3 thin films at 193nm by thermal evaporation,�?? Appl. Opt. 44, 7333-7338 (2005).
[CrossRef] [PubMed]

2004 (1)

Y. Taki, "Film structure and optical constants of magnetron-sputtered fluoride films for deep ultraviolet lithography," Vacuum 74, 431-435 (2004).
[CrossRef]

2002 (2)

S. Niisaka, T. Saito, J. Saito, A. Tanaka, A. Matsumoto, M. Otani, R. Biro, C. Ouchi, M. Hasegawa, Y. Suzuki, and K. Sone, �??Development of optical coatings for 157-nm lithography I coating materials,�?? Appl. Opt. 41, 3242-3247 (2002).
[CrossRef] [PubMed]

K. Iwase, P. C. Selvin, G. Sato, and T. Fujii, "Mass spectrometric studies of ionic products in CF4/He and CF4/O2/He microwave discharge plasmas," J. Phys. D: Appl. Phys. 35, 1934-1938 (2002).
[CrossRef]

1995 (1)

A. Zuber, N. Kaiser, and J.L. Stehle, "Variable-angle spectroscopic ellipsometry for deep UV characterization of dielectric coating," Thin Solid Films 261, 37-43 (1995).
[CrossRef]

1985 (1)

1984 (1)

1982 (1)

M. J. Kushner, "A kinetic study of plasma-etching process. I. A model for the etching of Si and SiO2 in CnFm/H2 and CnFm/O2 plasmas," J. Appl. Phys. 53, 2923-2938 (1982).
[CrossRef]

Biro, R.

Carniglia, C. K.

Craighead, H. G.

Hasegawa, M.

Kaiser, N.

A. Zuber, N. Kaiser, and J.L. Stehle, "Variable-angle spectroscopic ellipsometry for deep UV characterization of dielectric coating," Thin Solid Films 261, 37-43 (1995).
[CrossRef]

Kaneko, M.

M. C. Liu, C. C. Lee, M. Kaneko, K. Nakahira, and Y. Takano, "Microstructure related properties at 193nm of MgF2 and GdF3 films deposited by resistive heating boat," Appl. Opt. 45, 1368-1374 (2006).
[CrossRef] [PubMed]

C. C. Lee, M.C. Liu, M. Kaneko, K. Nakahira, and Y. Takano, �??Characterization of AlF3 thin films at 193nm by thermal evaporation,�?? Appl. Opt. 44, 7333-7338 (2005).
[CrossRef] [PubMed]

M. C. Liu, C. C. Lee, M. Kaneko, K. Nakahira, and Y. Takano, "Microstructure related properties of Lanthanum Fluoride Films Deposited by Molybdenum Boat Evaporation at 193 nm," Thin Solid Films 492/1-2, 45-51 (2005).
[CrossRef]

Kushner, M. J.

M. J. Kushner, "A kinetic study of plasma-etching process. I. A model for the etching of Si and SiO2 in CnFm/H2 and CnFm/O2 plasmas," J. Appl. Phys. 53, 2923-2938 (1982).
[CrossRef]

Lee, C. C.

Lee, C. C.

C. C. Lee, M.C. Liu, M. Kaneko, K. Nakahira, and Y. Takano, �??Characterization of AlF3 thin films at 193nm by thermal evaporation,�?? Appl. Opt. 44, 7333-7338 (2005).
[CrossRef] [PubMed]

Liao, B. H.

Liu, M. C.

Liu, M. C.

C. C. Lee, M.C. Liu, M. Kaneko, K. Nakahira, and Y. Takano, �??Characterization of AlF3 thin films at 193nm by thermal evaporation,�?? Appl. Opt. 44, 7333-7338 (2005).
[CrossRef] [PubMed]

Liu, M. C.

M. C. Liu, C. C. Lee, M. Kaneko, K. Nakahira, and Y. Takano, "Microstructure related properties of Lanthanum Fluoride Films Deposited by Molybdenum Boat Evaporation at 193 nm," Thin Solid Films 492/1-2, 45-51 (2005).
[CrossRef]

Lowdermilk, W. H.

Maloney, P. J.

Matsumoto, A.

Milam, D.

Nakahira, K.

M. C. Liu, C. C. Lee, M. Kaneko, K. Nakahira, and Y. Takano, "Microstructure related properties at 193nm of MgF2 and GdF3 films deposited by resistive heating boat," Appl. Opt. 45, 1368-1374 (2006).
[CrossRef] [PubMed]

M. C. Liu, C. C. Lee, M. Kaneko, K. Nakahira, and Y. Takano, "Microstructure related properties of Lanthanum Fluoride Films Deposited by Molybdenum Boat Evaporation at 193 nm," Thin Solid Films 492/1-2, 45-51 (2005).
[CrossRef]

C. C. Lee, M.C. Liu, M. Kaneko, K. Nakahira, and Y. Takano, �??Characterization of AlF3 thin films at 193nm by thermal evaporation,�?? Appl. Opt. 44, 7333-7338 (2005).
[CrossRef] [PubMed]

Niisaka, S.

Otani, M.

Ouchi, C.

Rainer, F.

Saito, J.

Saito, T.

Sone, K.

Stehle, J.L.

A. Zuber, N. Kaiser, and J.L. Stehle, "Variable-angle spectroscopic ellipsometry for deep UV characterization of dielectric coating," Thin Solid Films 261, 37-43 (1995).
[CrossRef]

Suzuki, Y.

Sweeney, J. E.

Takano, Y.

M. C. Liu, C. C. Lee, M. Kaneko, K. Nakahira, and Y. Takano, "Microstructure related properties at 193nm of MgF2 and GdF3 films deposited by resistive heating boat," Appl. Opt. 45, 1368-1374 (2006).
[CrossRef] [PubMed]

C. C. Lee, M.C. Liu, M. Kaneko, K. Nakahira, and Y. Takano, �??Characterization of AlF3 thin films at 193nm by thermal evaporation,�?? Appl. Opt. 44, 7333-7338 (2005).
[CrossRef] [PubMed]

M. C. Liu, C. C. Lee, M. Kaneko, K. Nakahira, and Y. Takano, "Microstructure related properties of Lanthanum Fluoride Films Deposited by Molybdenum Boat Evaporation at 193 nm," Thin Solid Films 492/1-2, 45-51 (2005).
[CrossRef]

Taki, Y.

Y. Taki, "Film structure and optical constants of magnetron-sputtered fluoride films for deep ultraviolet lithography," Vacuum 74, 431-435 (2004).
[CrossRef]

Tanaka, A.

Wood, O. R.

Zuber, A.

A. Zuber, N. Kaiser, and J.L. Stehle, "Variable-angle spectroscopic ellipsometry for deep UV characterization of dielectric coating," Thin Solid Films 261, 37-43 (1995).
[CrossRef]

Appl. Opt. (6)

J. Apply. Phys. (1)

M. J. Kushner, "A kinetic study of plasma-etching process. I. A model for the etching of Si and SiO2 in CnFm/H2 and CnFm/O2 plasmas," J. Appl. Phys. 53, 2923-2938 (1982).
[CrossRef]

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

K. Iwase, P. C. Selvin, G. Sato, and T. Fujii, "Mass spectrometric studies of ionic products in CF4/He and CF4/O2/He microwave discharge plasmas," J. Phys. D: Appl. Phys. 35, 1934-1938 (2002).
[CrossRef]

Opt. Express (1)

Thin Solid Films (2)

A. Zuber, N. Kaiser, and J.L. Stehle, "Variable-angle spectroscopic ellipsometry for deep UV characterization of dielectric coating," Thin Solid Films 261, 37-43 (1995).
[CrossRef]

M. C. Liu, C. C. Lee, M. Kaneko, K. Nakahira, and Y. Takano, "Microstructure related properties of Lanthanum Fluoride Films Deposited by Molybdenum Boat Evaporation at 193 nm," Thin Solid Films 492/1-2, 45-51 (2005).
[CrossRef]

Vacuum (1)

Y. Taki, "Film structure and optical constants of magnetron-sputtered fluoride films for deep ultraviolet lithography," Vacuum 74, 431-435 (2004).
[CrossRef]

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.

Schematic diagram of the sputtering system.

Fig. 2.
Fig. 2.

Transmittance spectra of AlF3 thin films prepared with and without O2 gas at the same sputtering time and power.

Fig. 3.
Fig. 3.

Transmittance spectra of AlF3 films prepared with 30W power and 60sccm CF4 mixed with various O2 gas flow rates at the same sputtering time.

Fig. 4.
Fig. 4.

Thickness of AlF3 thin films prepared with different O2 flow rates at the same sputtering power and time.

Fig. 5.
Fig. 5.

Refractive indices of AlF3 thin films prepared with different flow rates of O2 gas at 30 sputtering power.

Fig. 6.
Fig. 6.

Extinction coefficient of AlF3 thin films prepared with different flow rates of O2 gas at 30W sputtering power.

Fig. 7.
Fig. 7.

Transmittance spectra of AlF3 films prepared with (a) 60sccm CF4 mixed with 12sccm O2 at 200W (b) 60sccm CF4 mixed with 12sccm O2 at 30W sputtering power (c) 60sccm CF4 at 200W.

Fig. 8.
Fig. 8.

Extinction coefficient of AlF3 thin films prepared with (a) 60sccm CF4 (b) 60sccm CF4 mixed with 12sccm O2 at both 200W sputtering power.

Fig. 9.
Fig. 9.

Refractive indices of AlF3 thin films prepared with (a) 60sccm CF4 (b) 60sccm CF4 mixed with 12sccm O2 at both 200W sputtering power.

Fig. 10.
Fig. 10.

Cross-sectional morphology of AlF3 thin films coated with 60sccm CF4 mixed with 12sccm O2 at 200 sputtering power.

Tables (1)

Tables Icon

Table 1. Surface roughness of AlF3 thin films produced at the same sputtering powers with 60sccm CF4 and different O2 flow rates.

Metrics