Low Temperature Silicon Nitride Deposition by Inductively Coupled Plasma CVD for GaAs Applications

Abstract

In order to take advantage of silicon nitride films as an ILD layer on GaAs devices, the ICP CVD silicon nitride films were investigated by parametric study of effects of deposition parameters on the physical properties of silicon nitride film deposited in the range of 50 ~ 200oC temperature. Good quality of films could be achieved, including low moisture absorption, low H content (<15 at.%), good resistance to BOE etching (<50 Aå/min), smooth film surface (2.0 nm roughness), and reasonable film stress, as compared to the conventional PECVD nitride film, while the process temperature is much lower than the conventional PECVD process. This silicon nitride film was applied to the GaAs HBT device structure and showed very promising results of the gap-filling capability and planarization for next level of metallization. These results indicate the possibility of using the ICP CVD silicon nitride films as an ILD layer in the GaAs devices instead of polymer type dielectrics, which typically require a long cure time at high temperature of 300oC or higher.