| 摘要 |
PURPOSE:To continue optical CVD for a long time without reducing the light tansmittance of a window by optically etching the deposit on the light radiating window during the optical CVD process. CONSTITUTION:The raw gas such as Si2H4 is photochemically decomposed by a low-pressure mercury lamp 6, and a thin film of amorphous silicon, etc., is formed on a substrate 1 of Si, etc. In this case, an etching gas such as Cl2 which reacts with the thin film deposit on the incident window 8 for transmitting the light of the lamp 6 to form a volatile compd. is blown from a nozzle 11 on the window 8. The light such as XeC laser 9 as the light source which activates and excites the gaseous Cl2, etc., to promote the reaction with the deposit is radiated through a side window 10. CVD is thus performed while optically etching the deposit on the incident window 8 with the gaseous Cl2, etc., and CVD can be carried out while keeping the deposition rate constant for a long time.
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