Side-Wall Angle Uniformity Improvement in Shallow Trench Isolation Process

In shallow trench isolation (STI) process, side-wall angle is an important parameter to achieve high quality isolation silicon oxide filling. Here, HBr, and O2 are utilized as the main etch gases to etch silicon in STI by inductively coupled plasma etcher, with a much side-wall angle center/edge difference. To deal with the situation, two methods are studied: adding dilute gas, and optimizing electrical static chuck temperature. Both of them are effective to improve side-wall angle uniformity, which enhances the yield of STI process in wafer fabrication.