Disclosed herein are various methods and structures using contacts to create differential stresses on devices in an integrated circuit (IC) chip. An IC chip is disclosed having a p-type field effect transistor (PFET) and an n-type field effect transistor (NFET), a PFET contact to a source/drain region of the PFET and an NFET contact to a source/drain region of the NFET. In a first embodiment, a silicon germanium (SiGe) layer is included only under the PFET contact, between the PFET contact and the source/drain region of the PFET. In a second embodiment, either the PFET contact extends into the source/drain region of the PFET or the NFET contact extends into the source/drain region of the NFET.