PECVD腔室热流场数值仿真研究

Simulation of Flow and Thermal Field in a PECVD Reaction Chamber

等离子辅助化学气相沉积(PECVD)腔室的气流分布、温度分布是影响薄膜沉积工艺均匀性以及沉积速率的重要原因之一。本文对PECVD腔室气流建立连续流体和传热模型,研究了腔室内流场和温度分布特性;讨论了四种不同稳流室结构的PECVD腔室,在加热盘恒温400℃、质量流量5000 sccm、抽气口压力133 Pa的工艺条件下12英寸晶圆片附近上方流速、压力、温度分布情况;选择了其中一种稳流室结构作了多种质量流量(20～5000 sccm)入口条件下的流场分析。仿真研究发现:在抽气口位置偏置的情况下,四种不同稳流室结构的腔室内热流场并未出现明显偏置,这表明抽气口偏置对工艺均匀性没有明显影响。加热盘附近上方2 mm处温度场大面均匀、稳定,且随入口质量流量变化波动很小,表现出良好的稳定性;气压分布呈现中心高边缘低的抛物线特征,流速呈现中心低边缘高的线性特征,且晶圆片附近以及喷淋头(Showerhead)入口压力和流速均随着入口质量流量的增加而升高。研究结果对PECVD腔室结构设计及工艺控制具有重要意义。

The distribution of gas flow and temperature is one of the most important reasons that account for the film uniformity and deposition rate of Plasma enhanced chemical vapor deposition （PECVD）. This paper analyzed the gas flow and temperature distribution of the PECVD chamber based on the continuous fluid and heat transfer model, and discussed the gas flow velocity pressure and temperature distribution near the wafer based on four kinds of flow stabilized chamber at the condition of 400 ℃ heat-platform, 5000 sccm gas flowing into and 133 Pa pressure on the exhaust port. Then we compared the results, and discussed the flow filed at different mass flow （20-5000 sccm） inlet condition on the one model. The result shows that the bias of thermal and flow field inside the chamber are insignificant, though the exhaust port is biased, which indicates that the biased exhaust port has little influence on process uniformity. The thermal filed is uniform and stable, near the heater, and has a little fluctuation with the mass flow of inlet, which shows good stability ; the pressure distribution has the parabolic character which the pressure is higher at the center and lower at the edge character which the velocity is slower at the center and and the flow velocity distribution has the linear faster at the edge; the gas flow pressure andvelocity near the wafer and showerhead inlet increase with the rise of the inlet mass flow. The result has important significance on design of chamber structure and control of process.