Silicon precursor gases - SIAD Società Italiana Acetilene e Derivati
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Silicon precursor gases
Silicon-precursor gases act as a source of silicon atoms for the deposition of polycrystalline silicon, epitaxial silicon, silicon dioxide, and silicon nitride.
The most common gases are silane, dichlorosilane, trichlorosilane, and silicon tetrachloride. Silicon-precursor gases such as silane and dichlorosilane are used in epitaxial and chemical vapour depositon (CVD) processes to deposit layers of silicon or silicon compounds onto silicon substrates.
Silicon epitaxial layers are formed in reactions based on the mechanisms of thermal decomposition or reduction by hydrogen, depending on the silicon-precursor reactant gas used.
Each silicon-precursor gas has epitaxial processing advantages and disadvantages, including processing temperature range, degree of autodoping and growth rates.
Current trends indicate increasing use of dichlorosilane over the high-deposition temperature trichlorosilane and silicon tetrachloride:
- Silane is used throughout a wafer production site, or fab, in numerous Chemical Vapour Deposition processes to form oxide, nitride and polysilicon thin films.
- Dichlorosilane, in a gaseous state at 0.5 atmosphere, is also a primary source for polysilicon deposition.
- Trichlorosilane and silicon tetrachloride are both corrosive liquids at room temperature and pressure.
- Methylsilane is used for deposition of silicon carbide files.
- Germane is used for silicon-germanium epitaxy for bandgap modification.