Method of forming a semiconductor device with multiple tensile stressor layers

Abstract

A semiconductor device has at least two tensile stressor layers that are cured with UV radiation. A second tensile stressor layer is formed after a first stressor layer. In some examples, the tensile stressor layers include silicon nitride and hydrogen. In some examples, the second tensile stressor layer has a greater shrinkage percentage due to the curing than the first tensile stressor layer. In one form, the second tensile stressor layer after the curing exerts a greater tensile stress than the first tensile stressor layer. The tensile stressors layers are utilized to improve carrier mobility in an N-channel transistor and thus enhance transistor performance. In one form a single group of overlying tensile stressor layers is provided with each layer being increasingly thicker and having increasingly more hydrogen prior to being cured. In other embodiments multiple overlying groups are formed, each group having a similar repeating depth and hydrogen profile.