The Influence of Thermal Silicon Nitride Formation on VLSI Fabrication

Thinning of SiO2 film in a MOS FET gate and memory capacitor can rduce such adverse effects as a short channel effect, subthreshold current, α-prticle disturbance, etc. An insulator having a dielectric constant higher than that of SiO2 provides the same benefits as does thinning the SiO2 film. From this viewpoint, the characteristics of thermal silicon nitride (SiN) film have been investigated with the hope of developing higher-density Si VLSI.(l) There has been, however, no report of SiN formation influence on Si substrate characteristics after SiN removal. In the context of VLSI fabrication, we investigated this influence on effective electron mobility (μ ef) of SiN-gate FET and on the dielectric breakdown (DB) of SiO2 grown after SiN removal (SiO2(SiN)). In addition, we studied B, P and Sb diffusion in Si during nitridation.