面向布气均匀性的竖直式喷淋头布气系统优化设计

Numerical Optimization of a Showerhead System for the Distribution of Gas Flow Uniformity

竖直式喷淋头布气系统在半导体工艺腔室类设备中广为采用,其布气均匀性是决定半导体工艺均匀性的关键因素之一。以布气均匀性为驱动,对竖直式喷淋头布气系统进行优化设计。在优化策略设计中为解决传统参数优化方法优化喷淋头多孔板面时需要预先确定拓扑结构、人为缩小参数空间造成系统分辨率低的问题,提出描述喷淋头多孔板面等效阻抗模型,将喷淋头板面小孔结构和布局的优化问题转换为喷淋头板面对气体流动的阻抗特性优化问题,进而建立了高分辨率的喷淋头板面阻抗分布优化模型。优化的喷淋头板面阻抗分布使得喷淋头的布气不均匀性（在N2质量流量1.041 7×10^–4 kg/s、腔室压力266Pa典型工艺条件下）由0.36%降低至0.03%。采用CFD数值试验对优化的竖直式喷淋头布气系统在入口气体质量流量6.250 0×10^–5-1.666 7×10^–4 kg/s、腔室压力133-665 Pa的工艺范围内进行测试,结果表明：优化的喷淋头系统布气效果均优于对照的喷淋头系统,其布气不均匀性均好于0.35%。针对喷淋头板面小孔布局及结构,列举3种拓扑调整方案,并根据阻抗优化结果给出对应的优化的几何配置实例。

A vector showerhead gas delivery system is widely applied to integrated circuit manufacturing equipments, including process chamber, and the uniformity of gas distribution is one of the key factors to affect the process uniformity. The uniformity of gas distribution is taken as an objective to drive the optimization design of the vector showerhead system. In order to solve the problem that the conventional parameter optimization methods for the showerhead porous face plate need a pre-determined topology and narrow the parameter dimension that leads to a poor system resolution, an equivalent impedance model is proposed to describe the showerhead porous face plate in the optimization strategy. This model translates the optimization problem of the holes structure and layout into optimizing the flow impedance feature of the showerhead face plate, and then a high-resolution optimization model can be established for the distribution of the impedance. The nonuniformity of gas distribution of the optimal showerhead system is reduced from 0.36% to 0.03%（under the process condition of 1.041 7×10–4 kg/s of nitrogen and 266 Pa）. A CFD numerical experiment is applied to test the performance of the optimal showerhead system under the varied conditions that the inlet mass flow is 6.2500×10^–5 1.666 7×10^–4 kg/s and the pressure is 133-665 Pa. The result shows that the performance of the optimal showerhead system is better than the compared one at the entire range of the process condition, and the nonuniformity is under 0.35%. Finally, 3 topology adjustment cases for the layouts and structures of the holes on the showerhead face plate are shown, and the optimal geometry configuration instances are illustrated correspondingly.