Prevent defocus issue on wafer with tungsten coating on back-side

摘要

A method is provided to prevent the forming of a high de-focusing ledge or step on the back side of a substrate or a semiconductor wafer in order to improve the photolithographic process steps in semiconductor manufacturing. In semiconductor manufacturing, various processes are performed to form various dielectric and metal layers on the front side of wafers. However, some of these materials deposit on the back side of the wafer as well. These unwanted deposits result in contaminants that break off from the back side, causing reliability problems. Those that do stay on, on the other hand, cause irregular topology, thus affecting the focusing of stepper equipment during photolithographic processes. It is disclosed in the present invention a method of forming an oxide layer which prevents the forming of such de-focusing steps on the back side of a wafer.