6 / 2019-03-09 13:08:05

Silicon Membrane Thickness Monitoring System based on Optical Sensing

Silicon etching, silicon membrane thickness monitoring, light absorption, optical sensing, photodiode.

In the fabrication of MEMS (Microelectromechanical Systems) devices, it is frequently needed to precisely monitor and control the thickness of silicon membrane during etching process. In this paper, a simple and effective silicon membrane thickness in-situ monitoring system based on optical sensing is reported. It utilizes light absorption to monitor silicon membrane thickness during wet etching. By measuring the light intensity loss passing through the silicon membrane, its thickness can be derived. The proposed method is contactless, non-destructive, and it allows continuing thickness monitoring during etching process. By combining it with Arduino microcontroller, it would allow real-time monitoring and smart control of the target membrane thickness in etching process during MEMS device fabrication.