Rlsa cvd deposition control using halogen gas for hydrogen scavenging

Abstract

Film thickness uniformity and stoichiometry are controlled and deposition rate is increased in the chemical vapor deposition (CVD) of silicon nitride from complex gas mixtures in microwave plasmas. In SiH+NH+Ar gas mixtures using a radial line slot antenna (RLSA) microwave plasma to deposit SiN by CVD, deposition rate and film uniformity are improved by limiting the amounts of atomic or molecular hydrogen from the gas mixture during the deposition process. A halogen, for example, fluorine, is added to a gas mixture of silane or disilane, ammonia and argon. The halogen scavenges hydrogen from the mixture, and prevents the hydrogen from blocking the nitrogen and silicon atoms and their fragments from bonding to the surface atoms and to grow stoichiometric silicon nitride. Adding the halogen generates free halogen radicals that react with hydrogen to create hydrogen halide, for example, HF or HCl, thereby scavenging the hydrogen.