LS-MOCVD的真空度测量及自动控制

Design of Vacuum Measurement and Autocontrol for LS-MOCVD

对液态源金属有机物化学气相沉积（Liquid Source-Metal Organic Chemical Vapor Deposition，LS-MOCVD）设备．文中主要研究了LS-MOCVD的反应室真空获取和控制的方法．整个设备的操作控制由PLC和触摸屏协作完成，用冷阴极电离全量程规测量粗真空，用高精度薄膜规测量工艺过程中的真空，采用内置PID算法的智能蝶阀控制器构成高真空恒压测量控制回路，实现了LS-MOCVD反应室真空的自动测量控制，确保了工艺的稳定性．反应室真空测量范围为常压～8×10^-3Pa，测量精度0．2％，分辨率为满量程的0．0015％．解决了传统气态源MOCVD不同材料之间蒸汽压差大、难以控制及气态金属有机物难以获得的问题．

The important excellence of LS-MOCVD equipment is using metal organic compounds as precursor. The vapor pressure difference between various materials in conventional gas-source MOCVD equipment is too large to control, and gas metal organic compounds is difficult to be obtained. LS- MOCVD provides an effective method for making and researching ferro- electric thin films , superconductive thin films, oxide electrode thin films and so on, all of which can use liquid source as precursor. The method for measuring and controlling vacuum in LS-MOCVD reaction chamber is presented in detail. PLC and touch panel is used to control this equipment. Cold cathode ionization gauge is used to measure coarse vacuum. High accuracy gauge is used to measure vacuum in depositing process. Intelligent butterfly valve controller with internal PID algorithm is composed loop to measure and control high vacuum and constant pressure. Vacuum in LS- MOCVD reactor chamber is automatically controlled and ensures the stability of the process. Vacuum measurement range is atmospheric pressure to 8×10^-3 Pa. Vacuum measurement accuracy reaches 0. 2%. Vacuum resolution achieves 0. 0015% of full range.