When forming sophisticated transistors on the basis of a high-k metal gate electrode structure and a strain-inducing semiconductor alloy, a superior wet cleaning process strategy is applied after forming cavities in order to reduce undue modification of sensitive gate materials, such as high-k dielectric materials, metal-containing electrode materials and the like, and modification of a threshold voltage adjusting semiconductor alloy. Thus, the pronounced dependence of the threshold voltage of transistors of different width may be significantly reduced compared to conventional strategies.