Direct temperature monitoring for semiconductors in plasma immersion ion implantation

In situ temperature monitoring is extremely important in plasma immersion i on implantation (PIII) of semiconductors. For instance, the silicon wafer m ust be heated to 600 degrees C or higher in separation by plasma implantati on of oxygen, and in the PIII/ion-cut process, the wafer temperature must r emain below 300 degrees C throughout the experiment. In this article, we pr esent a thermocouple-based direct temperature measurement system for planar samples such as silicon wafers. In order to ensure reliable high-voltage o peration and overall electrical isolation, the thermocouple assembly and wi res are integrated into the sample chuck and feedthrough. Hydrogen plasma i mmersion ion implantation is performed in silicon to demonstrate the effect iveness and reliability of the device. Our experimental results indicate th at instrumental parameters such as implantation voltage, pulse duration, an d pulsing frequency affect the sample temperature to a different extent. Th e measured temperature rise is higher than that predicted by a theoretical model based on the Child-Langmuir law. The discrepancy is attributed to the finite-sample size and the nonplanar, conformal plasma sheath. (C) 2000 Am erican Institute of Physics. [S0034-6748(00)02307-8].