以電漿化學氣相沉積法製備氮化矽之製程模擬與電漿模型分析研究

本研究建立一套氮化矽薄膜製程之反應機制。先以零維反應器模型求解，接著再以二維反應器模型求解薄膜沉積速率，並探討不同操作參數對製程之影響。首先建立氮化矽之電漿化學氣相沉積反應機制，以零維模型求解。研究中發現，依據文獻所建立之氮化矽反應機構不失模型精準度，隨著功率提高、壓力降低及總流量增加，氮化矽薄膜沉積速率隨之升高。此外，隨著氨氣的進氣比例增加時，鍍膜速率也會增加且氮矽比在氨氣矽烷進氣比為4時高達1.3，與氮化矽理論值相當接近約1.33。我們也利用物種生成速率分析(Rate-of-production Analysis)去探討影響鍍膜速率之因素，主要由3種鍍膜粒子(SiH3、SiH2、SiHNH2)來控制鍍膜速率。最後將上述所建立之氮化矽反應機制匯入商業軟體CFD-ACE+，以二維模型求解。我們先以兩種不同電極配置之模型，並選取最佳模型進行深入探討，並透過不同參數條件來探討鍍膜均勻性。研究發現，在改變功率時，當功率提高至200W之後，在腔體內形成了兩個電漿區，鍍膜速率較高但其均勻性不佳；在調整不同壓力時，在模型中可以發現Ambipolar diffusion的情況，在壓力較小時擴散速率較快；在壓力較大時擴散速率較慢，造成腔體中心至出口處之正離子濃度之變化，最後在功率充足且壓力較高的情況下，鍍膜均勻性較佳。本研究所建立之模型可有效地探討電漿化學氣相沉積中複雜之化學反應機制。

關鍵字

電漿化學氣相沉積；動力學模型；氮化矽；鍍膜；均勻性

並列摘要

In this study, numerical analysis of plasma enhance chemical vapor deposition (PECVD) of silicon nitride (SiNx) process was performed by zero-dimension (0-D) chemical kinetics modeling and two-dimensional (2-D) computational-fluid-dynamics (CFD) simulations. A suitable reaction mechanism consists of 34 species, 49 gas-phase reactions and 25 surface reactions was applied to both 0-D and 2-D models to investigate the influence of process parameters on the plasma characteristics and the film deposition process. It was found that the SiNx deposition rate predicted by zero-dimension model agree well with the experimental data from the literature. The model show that the film growth rate increases as input power and silane flowrate increase. In addition, as the ammonia/silane flowrate ratio increases, the N/Si atomic ratio in the deposited film also increases. The two-dimensional model was established via CFD-ACE+ software. The influence of various process parameters on the deposition rate, N/Si ratio, and the film uniformity were compared. The result indicate that the resident time is responsible for the effect of pressure on the deposition rate and the SiNx film uniformity across the substrate. In conclusion, this study has successfully developed two models to simulate the complex physical-chemical process in PECVD of SiNx film.