Patent ID: 6054741
Filing Date: 2000-04-25
Classification: H01L

Abstract:
A semiconductor device having a substrate comprising:an insulation layer required region with a first field oxide layer existing thereon and being formed on said substrate, wherein the insulation layer required region is located on the substrate at locations necessary to provide electrical isolation,an impurity doping required region for requiring doping of impurities, and being formed on said substrate,an impurity doping forbidden region for forbidding doping of said impurities, being neither said insulation layer required region nor said impurity doping required region, and being formed on said substrate, wherein the impurity doping forbidden region is located on the substrate at locations necessary to cover an upper part of an active base of a bipolar type transistor,a second field oxide layer formed in common with the first field oxide layer and formed on said impurity doping forbidden region,and wherein, said second field oxide layer does not affect substantially the function of said semiconductor device.