Evaluation of Hafnium Contamination on Wafer Surfaces after the Wet Cleaning Process

Abstract

High-k gate dielectrics and metal gate electrodes have become essential for emerging device technologies because they enable the continuous scaling down of devices while maintaining a high performance [. However, since they are composed of novel metallic elements that have never before been used in conventional processes, special care must be taken when handling these materials in the production line. In particular, cross-contamination that occurs due to transporting contamination via processed wafers can cause serious problems such as deterioration of device properties and yield loss [. The process of cleaning the backside and bevel of a wafer is now increasingly important for avoiding these problems. To date, there has been no detailed evaluation of contamination removal on various films performed for elements such as hafnium, which is one of the key elements in high-k/metal gate technologies. In this study, we evaluated hafnium contamination on three types of wafer surface after the cleaning process and investigated the cause of different residual amounts of hafnium contamination on the different wafers.