Patent ID: 7439135

Claim:
A method comprising: forming set of mandrels on a top surface of a substrate, each mandrel of said set of mandrels arranged on a different corner of a polygon and extending above said top surface of said substrate, a number of mandrels in said set of mandrels equal to a number of corners of said polygon; forming sidewall spacers on sidewalls of each mandrel of said set of mandrels, sidewalls spacers of each adjacent pair of mandrels merging with each other and forming a unbroken wall defining an opening in an interior region of said polygon, a region of said substrate exposed in said opening; etching a contact trench in said substrate in said opening; filling said contact trench with an electrically conductive material to form said contact; and wherein said substrate is a silicon substrate and includes a buried oxide layer separating said substrate into an upper silicon layer on a top surface of said buried oxide layer and a lower silicon layer under said buried oxide layer.