Patent ID: 6221737
Filing Date: 2001-04-24
Classification: H01L

Abstract:
A method of making a semiconductor device having a semiconductor substrate, a thin buried oxide insulating layer on said substrate, and a lateral semiconductor device provided in a thin semiconductor film on said thin buried oxide, said thin semiconductor film comprising a first region of a first conductivity type, a second region of a second conductivity type opposite to that of the first and spaced apart from said first region by a lateral drift region of said second conductivity type, a top oxide insulating layer over said thin semiconductor film, and a conductive field plate on said top oxide insulating layer, wherein said top oxide insulating layer comprises a layer portion adjacent said first region which increases in thickness in a substantially continuous manner in a direction from said first region toward said second region over a distance of at least about a factor of five greater than a maximum thickness of said thin semiconductor film, and said lateral drift region comprises a region portion adjacent said first region which decreases in thickness in said substantially continuous manner in a direction from said first region toward said second region over said distance, the method comprising:forming an oxidation mask comprising silicon nitride on said thin semiconductor film; thenpatterning a portion of said oxidation mask with a series of sequential openings of different widths, a portion of said openings having a width less than a maximum thickness of said top oxide insulation layer; and thenthermally oxidizing said thin semiconductor film using said oxidation mask to grow said top oxide insulation layer with said layer portion which increases in thickness and to form said lateral drift region with said region portion which decreases in thickness.