SOURCE AND DRAIN REGIONS, CONTACT HOLES AND FABRICATION METHODS THEREOF

摘要

A source/drain region includes a first region of which at least part of thickness is in the substrate, and a second region being on the first region and having different material from the first region. A method of fabricating the source/drain region includes forming recesses in the substrate beside two sides of the gate stack, forming a first semiconductor layer with at least part of which the recesses are filled, and forming a second semiconductor layer on the first semiconductor layer, with the material of the second semiconductor layer different from that of the first semiconductor layer. A contact hole and a fabrication method thereof are also disclosed, which can increase the contact area between the contact hole and the contact region, and can reduce the contact resistance.