Patent ID: 7612405
Filing Date: 2009-11-03
Classification: H01L

Abstract:
1. A semiconductor structure comprising: a semiconductor substrate; a first semiconductor strip extending from a top surface of the semiconductor substrate into the semiconductor substrate, wherein the first semiconductor strip has a first height; a first insulating region in the semiconductor substrate and surrounding a bottom portion of the first semiconductor strip, wherein the first insulating region has a first top surface lower than a top surface of the first semiconductor strip; a second semiconductor strip extending from the top surface of the semiconductor substrate into the semiconductor substrate, wherein the second semiconductor strip has a second height greater than the first height of the first semiconductor strip; and a second insulating region in the semiconductor substrate and surrounding a bottom portion of the second semiconductor strip, wherein the second insulating region has a second top surface lower than the first top surface of the first insulating region, and wherein the first and the second insulating regions have substantially same thicknesses.