Silicon deposition from vapour phase - with substrate temp. periodically lowered and raised between optimum and minimum

摘要

Silicon in fine crystalline form is deposited from the vapour phase on a substrate which is heated by the passage of current. At a set molar ratio of the reactant gas and a chosen gas flow rate, the starting temp. of the substrate is set to 1100 degrees C. This temp. is lowered in accordance with a set programme to a min., followed by raising it to 1100 degrees C. This is repeated several times with or without holding it at 1100 degrees C. This achieves during the mfr. of polycrystalline Si rods a good si halogen yield, combined with a good fine-crystalline surface of the Si, and not one or the other as in conventional procedures.