A novel wireless on-wafer plasma sensor using light-emitting diodes

We developed a novel wireless, on-wafer plasma sensor that uses light-emitting diodes (LEDs). This sensor measures the potential differences during plasma exposure that are a factor in charging damage occurring in semiconductor devices. The sensor's measurement principle is based on the diode characteristics and the measurement is very easy; we need only to expose the sensor to plasma and count the in-series LEDs that are bright. If they are bright, it means the applied voltage exceeds a known critical value. If they are dark, it means the voltage is below the value. Thus the sensor uses light for data acquisition, and no wire connections are necessary. Furthermore, it can be handled like a standard wafer. Its fundamentally quick and inexpensive measurement feature makes it highly advantageous for application to conventional measurements. This novel sensor makes it possible to measure plasma properties and minimize the potential of charging damage in real time.