ETCHING METHOD

摘要

PURPOSE:To prevent the damage to a semiconductor substrate holder due to overetching during the etching removal of an insulator film attached in the vapor phase growth by coating it with an etching resistant thin film beforehand. CONSTITUTION:The semiconductor substrate holder 5 alone is inserted into a reaction tube heated by means of the LPCVD device (pressure reduction chemical phase accumulation) and coated on the surface with a polycrystaline Si film about 0.5mum thick under the reduced pressure by thermal cracking of SiH4 gas. As one coating is not enough because the contact portion with the inner wall of the tube may not be yet covered sufficiently or may be insufficient in thickness even if it covered entirely. Another polycrystaline Si film is formed on the holder 5 under the same conditions by turning it upside down. The holder thus treated is used to form the Si3N4 on the semiconductor substrate by the normal LPCVD method. This can protect the holder from any etching even if the Si3N4 film is removed emmersed in the HF liquid after used several time.