几种基于PLC的硅片清洗设备流量控制方法

Flowrate control methods based on PLC in wafer clean tool

主要讲述了在半导体硅片清洗设备中常用的几种流量控制方法,主要包括工艺腔室和药液配比的流量控制,然后根据不同应用场景提出了对应使用的控制方法。单腔室硅片清洗机直接采用流量作为反馈信号进行闭环控制,通过控制喷洒和返回管路开度的平衡,有利于降低气动阀切换时液体流量的波动幅度。多腔室清洗机采用压力闭环的控制方式来间接控制流量,磁悬浮泵串联控制设计可有效提升泵的使用寿命和压力稳定性,并通过调节各腔室针阀,减小了各个腔室工艺流量的差异性。多种药液配比功能一般通过控制各药液的注入流量来实现,流量精度直接影响药液成分的精度。基于可编程逻辑控制器(Programmable Logic Controller,PLC)的设备集成控制具有使用灵活、稳定性好、可靠性高的特点,适用于不同控制单元的实时、精确控制。

Several in common use flowrate control methods in semiconductor wafer clean tool are introduced in this paper,including the flowrate control of process chamber and chemical proportioning,then corresponding control methods are brought forward according to different applications.The chemical flowrate is directly used as the feedback signal of closed control in single chamber clean tool,and the fluctuation of chemical flowrate is reduced when the pneumatic valve is switched by controlling the balance between dispense and return tube opening.The pressure closed loop control method is adopted to control the flowrate indirectly in multi-chamber clean tool,the series control design of magnetic suspension pump can effectively improve the service life and pressure stability of the pump,and by adjusting the needle valve in each chamber,the difference of the flowrate of each chamber is reduced.Generally,by controlling the injection flowrate of each chemical,a variety of chemical mix functions can be realized.Flowrate precision directly affects the accuracy of the composition of process chemical.Clean tool integration control based on PLC has the features of flexble in use,good stability,and high dependability,and is applicable for real-time and precise control of different module.