Monitoring of rapid thermal anneal with secondary ion mass spectrometry

Abstract

Accurate monitoring and, thus, control of rapid thermal anneal (RTA) are critical for manufacturing semiconductor devices. In this work, we developed a method by using secondary ion mass spectrometry (SIMS) aimed to improve long-term repeatability in monitoring RTA. We used a test wafer in a batch implant as SIMS reference for the remaining wafers in the same batch and eliminated the impact from wafer aging and test wafer variation from lot to lot as often encountered in sheet resistance monitoring. In addition, the use of the normalized peak concentration of boron as measured by SIMS allows for repeatable analyses to capture 1 °C or lower drift in an RTA temperature higher than 1000 °C. The benefit of this SIMS approach has been validated by improvement in the device yield since the implementation of monitoring.