Prediction and Process Control Technique of Wafer Warpage for Advanced Trench Field Plate Power MOSFETs

Abstract

Trench Field-Plate (FP) MOSFET structure improves device characteristics. It is known, however, that trench FP-MOSFET causes wafer warpage in manufacturing process and causes wafer transfer errors in manufacturing equipment. We developed a stress-simulation model and predicted the wafer warpage change in a newly designed FP-MOSFET. By using the prediction, we could control the wafer warpage through the whole process. Moreover, we found a correlation between a trench angle and the wafer warpage after a field plate oxidation. The correlation is applicable to quality control for the trench angle in a wafer fab.