No CrossRef data available.
Article contents
Investigation of Pre-Tungsten Silicide Deposition Wet Chemical Processing
Published online by Cambridge University Press: 15 February 2011
Abstract
Removing the native oxide from the poly-Si surface prior to WSix deposition is essential for achieving high quality silicides as well as sufficient film adhesion, particularly after high temperature anneal or oxidation. Contact angle studies have been used to determine initial and time-dependent surface characteristics of several types of silicon surfaces following immersions in HF-based etchants for varying amounts of time. The morphological characteristics of the surfaces before and after exposure to etchants, as well as the relative etch rates and wetting capabilities of the etchants have been used to explain the following results: With respect to initial contact angle studies, the implanted & annealed polycrystalline silicon surface has the lowest contact angle followed by polycrystalline and monocrystalline surfaces. Longer immersion times yield lower initial contact angles. The 0.1% lightly-buffered HF solution results in the highest contact angle followed by the 1% buffered HF solution with surfactant, and the 1% HF solution. With respect to contact angle changes during ambient air exposure time, the asdeposited polycrystalline silicon surface is most stable followed by monocrystalline, and implanted & annealed polycrystalline silicon surfaces. Longer immersion times improve surface stability while the 0.1% lightly-buffered HF solution results in the most stable surface followed by the 1% buffered HF solution with surfactant, and the 1% HF solution.
- Type
- Research Article
- Information
- Copyright
- Copyright © Materials Research Society 1995
References
REFERENCES
1.
Chu, C., Moinpour, M., Cham, J., Lu, W., Hwang, D., Watt, V.H.C., Sadjadi, R., Gaynor, W., and Moghadam, F., ‘DCS Based CVD Tungsten Silicide Technology for Sub-Micron Flash Memory Applications’, IEEE/VMIC Conf. Proc., (1994).Google Scholar
2.
Moinpour, M., Moghadam, F., Cham, J., and Lu, W., ‘Composition and Structure of As-deposited and Oxidized DCS-Based CVD WSi, Films’, Mat. Res. Soc. Symp. Proc., Vol.337, (1994).Google Scholar
3.
Philipossian, A., ‘The Activity of HF/H2O Treated Silicon Surfaces in Ambient Air Before and After Gate Oxidation,’
J. Electrochem. Soc., Vol.139, No. 10 (1992).Google Scholar
4.
Kikuyama, H., Miki, N., Takano, J., and Ohmi, T., ‘Developing Property Controlled, High-Purity Buffered Hydrogen Fluorides for ULSI Processing,’ Medical Device and Diagnostic Industry, April (1989).Google Scholar
5.
Kikuyama, H., Miki, N., Saka, K., Takano, J., Kawanbe, I.
Miyashita, M., and Ohmi, T., ‘Surface Active Buffered Hydrogen Fluoride Having Excellent Wetability for ULSI Processing,’
IEEE Transactions on Semiconductor Manufacturing, Vol.3, No. 3, August (1990).Google Scholar
6.
Cerva, H., and Oppoizer, H., ‘Microstructure and Interfaces of Polysilicon in Integrated Circuits,’
Springer Proceedings in Physics, Vol.35 (1989).Google Scholar
7.
Duffy, M., McGinn, J., Shaw, J., Smith, R., Soltis, R., R., and Harbeke, G., ‘LPCVD Polycrystalline Silicon: Growth and Physical Properties of Diffusion-Doped, Ion- Implanted and Undoped Films,’
RCA Review, Vol.44, June (1983).Google Scholar
8.
Mei, L., Rivier, M., Kwark, Y., and Dutton, R., ‘Grain-Growth Mechanisms in Polysilicon,’
J. Electrochem. Soc., Vol.129, No. 8 (1982).Google Scholar
9.
Verhaverbeke, S., ‘Dielectric Breakdown of Thermally Grown Oxide Layers,’ Ph.D. Dissertation, Catholic University of Leuven, Belgium (1993).Google Scholar