Patent ID: 7504308
Filing Date: 2009-03-17
Classification: H01L,Y10S

Abstract:
1. A method of dual bird's beak LOCOS isolation, comprising: defining in a semiconductor substrate a low-voltage device area for a logic device and a high-voltage device area for a high-voltage device; forming a pad layer on the semiconductor substrate; selectively etching the pad layer in the low-voltage device area to reduce a thickness of the pad layer to form a first pad layer in the low-voltage device area and a second pad layer in the high-voltage device area, the first pad layer being thinner than the second pad layer; forming a hard mask on the first pad layer and the second pad layer; and forming at least one LOCOS type device isolation layer having bird's beaks differing in size in each of the low-voltage device area and the high-voltage device area, by oxidizing a portion of the semiconductor substrate exposed by the hard mask.