Patent ID: 8624295

Claim:
A semiconductor device comprising: a substrate having a top surface, the substrate being formed of a first semiconductor material having a first lattice constant; a first region comprising a first recess formed in the substrate and filled with a second semiconductor material, the second semiconductor material having a second lattice constant, the second semiconductor material extending above the top surface of the substrate and having a top surface; a second region comprising a second recess formed in the substrate and filled with the second semiconductor material; and an isolation region disposed between the first region and the second region, the isolation region having a first insulating layer and a second insulating layer, the first insulating layer extending into the substrate and having a horizontal top surface substantially coplanar with the top surface of the substrate, the second insulating layer being disposed directly on the horizontal top surface of the first insulating layer and extending above the top surface of the substrate, and sidewalls of the first insulating layer being coterminous with sidewalls of the second insulating layer; wherein the first and second insulating layer of the isolation region comprise different materials.