Patent ID: 8105894
Filing Date: 2012-01-31
Classification: H01L

Abstract:
1. A method for manufacturing a semiconductor device, comprising: depositing a first gate oxide film and a CMP stopper film in this order on an entire surface of a substrate; etching the first gate oxide film and the CMP stopper film using a resist pattern having an opening portion at an element isolation region; forming a trench at the element isolation region on the substrate; thermally oxidizing an exposed plane of the substrate in the trench to form a trench thermal oxide film; forming a liner insulating film at an interior wall of the trench; depositing a field insulating film over the entire surface of the substrate and planarizing the field insulating film until the CMP stopper film is exposed so that the trench is filled with the field insulating film; removing the CMP stopper film by wet etching, to form at the element isolation region on the substrate an element isolation film including the trench thermal oxide film, the liner insulating film, and the field insulating film; forming a first well of one of a first conductivity type and a second conductivity type at a first active region, the first active region being at least a part of a plurality of regions partitioned by the element isolation film on the substrate; and forming a first transistor on the first well; removing the first gate oxide film positioned at a prescribed region other than the first active region after forming the first well, and forming a second gate oxide film having a thickness smaller than that of the first gate oxide film; forming a second well of one of the first conductivity type and the second conductivity type at a second active region, the second active region being at least a part of a prescribed region other than the first active region among the plurality of regions partitioned by the element isolation film on the substrate; and forming on the second well a second transistor having a withstand voltage lower than that of the first transistor.