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.

Low Temperature Processing of Si-Based Dielectric Thin Films

“…Additionally, the issue of high film reliability at smaller film thicknesses required for future sub-micron devices is driving the R&D efforts on the evaluation of a variety of deposition processes and plasma techniques. Various thin film deposition techniques such as e-beam evaporation, RTCVD, PECVD, ECR-PECVD, chemical solution deposition, hot-wire CVD, etc., have been investigated for the low temperature processing of thin films [1][2][3][4][5][6][7][8][9][10]. However, there is no unique solution addressing the issues of low temperature processing, high throughput, and large area uniform deposition.…”

Comparison of Interlevel Dielectric Processes Using PECVD Silicon Nitride, Polyimide, and Polybenzoxazole for GaAs HBT Technology

“…One factor also to be considered is the gapfill capability of the interlevel dielectric material. In general, it is preferred that the material has good gapfill capabilities, as there will be cases when the space between structures will be too small and the aspect ratio too large (17,(25)(26)(27)(28). These will then result in difficulties to fill completely the gaps with the material, without any voids forming in the narrow spaces.…”

Photodefinable Polybenzoxazole as Interlevel Dielectric and Buffer Layer for GaAs HBT Technology

“…In GaAs technology, the typical films used for interlevel dielectric application include PECVD silicon nitride (Si 3 N 4 ), polyimide, and benzocyclobutene (BCB). The PECVD Si 3 N 4 is hard, conformal, and is excellent for protection against moisture absorption (16,(18)(19)(20)(21)(22). However, it has a high dielectric constant (κ=7.0), cannot be used as gapfill material, and does not planarize the underlying structures and topography on the GaAs, and therefore makes multilevel metallization challenging.…”