关键词: 半绝缘掺氧多晶硅, 耐压性能, 氧摩尔分数

Abstract: To enhance the within-wafer uniformity of semi-insulating polysilicon (SIPOS) films and the withstand voltage performance of devices, the synergistic effect of pressure and the N₂O/SiH₄ gas flow ratio (γ) in the low-pressure chemical vapor deposition process is systematically investigated. A series of SIPOS films are prepared by fixing the process temperature and adjusting the γ value and deposition pressure. The results indicate that film uniformity is insensitive to pressure variations at low γ values. However, under high γ conditions, low deposition pressure leads to significant radial and axial concentration gradients of reaction gases on the wafer surface. These gradients persist due to limited surface diffusion, resulting in within-wafer non-uniformity in both film thickness and oxygen content. This non-uniformity ultimately degrades the device's withstand voltage performance and reliability. Consequently, a moderate deposition pressure is identified as the optimal process window to balance excellent film uniformity with high withstand voltage characteristics.

Key words: semi-insulating polysilicon, withstand voltage performance, oxygen mole fraction