PE/RIE用自寻优功率匹配器的研究

STUDY OF THE SELF-OPTIMIZING POWER MATCHING NETWORK USED IN PLASMA ETCHING AND REACTIVE ION ETCHING

本文用分布参数电路理论对干法刻蚀(PE/RIE)机中从射频电源到反应真空室的功率传送电路进行了分析。用双口网络的分析方法推导出求解L型匹配网中可变电容C_P、C_M在负载Z_L下最佳匹配值C_P、C_M的计算公式。由于当反射功率P_(ref)等于零时射频放电光电信号V_L达到最大,通过测量一定负载条件下V_L与C_P、C_M的关系,提出了采用自寻优的控制策略实现自动匹配的新方法。这种方法比传统的鉴相鉴幅法自动匹配器电路简单、控制范围宽、稳定性好,有利于半导体干法刻蚀新工艺的开发和研究。自寻优匹配器由硬件和软件相结合的方法构成。硬件以8031单片微机为中心,软件采用改进的座标轮换成功失败法。经实际运行,稳定可靠,满足干法刻蚀工艺的要求。

The Radio Frequency power transmitting circuit from the RF generator to the vacuum chamber in a dry way etching (Plasma Etching or Reactive Ion Etching) system has been analyzed with the distributed parameter eleetrie/circuit theory. A formula to calculate the optimum matching point (C_(?), C_(?)) in the L type matching network under certain loading condition has been deduced with the twin-port network theory.Since RF discharge photo-electrlc conversion. signal V_L will reach the peak when the reflected power is zero, and through examining the relation of V_L and C_P and C_M under certain loading condition, a new automatic matching method by using the self-optimizing control strategy has been suggested. It has wider automatic matching range and its stability is better than the phase and amplitude discrimination method that is used overseas. The new self-optimizing matching method is favorable to developing the semiconductor dry way etching technology.The self-optimizing matching network is designed with hardware and software. The hardware uses 8031 chip microcomputer and some interface circuits. The software uses the improved coordinate conversion to and fro method. Through the experiments, it is stable, reliable, and meets the need of etching process.