Patent ID: 7335959
Filing Date: 2008-02-26
Classification: H01L

Abstract:
1. A device, comprising: a substrate having a top surface and first and second stepped source/drain recesses; a first stepped source/drain region in the first stepped source/drain recess, wherein the first stepped source/drain region includes a first layer of a first semiconductor material and a second layer of the first semiconductor material; a second stepped source/drain region in the second stepped source/drain recess, wherein the second stepped source/drain region includes a third layer of the first semiconductor material and a fourth layer of the first semiconductor material; wherein each of the first and second stepped source/drain recesses includes a first step extending to a first depth beneath the top surface of the substrate and a second step extending to a second depth beneath the top surface of the substrate, the second depth being deeper than the first depth; and wherein a smallest distance between the first step of the first stepped source/drain recess and the first step of the second stepped source/drain recess is smaller than a smallest distance between the second step of the first stepped source/drain recess and the second step of the second stepped source/drain recess.