Patent ID: 7612378
Filing Date: 2009-11-03
Classification: H01L

Abstract:
1. A semiconductor device comprising a semiconductor element having a semiconductor layer, an insulation film, and an electrode formed on a predetermined substrate, wherein said semiconductor element comprises a first impurity region formed at said semiconductor layer, a second impurity region formed at said semiconductor layer with a distance from said first impurity region, a channel region functioning as a channel having a predetermined channel length, formed at a portion of said semiconductor layer between said first impurity region and said second impurity region, a third impurity region formed in contact with said channel region at a portion of said semiconductor layer between said second impurity region and said channel region, and a fourth impurity region formed at a portion of said semiconductor layer between said second impurity region and said third impurity region, wherein, in said semiconductor element, said electrode has one side and another side opposite to each other, said fourth impurity region is coupled with said second impurity region and said third impurity region, an end of said first impurity region at said channel region side is located substantially on a same plane as said one side, and a junction between said third impurity region and said fourth impurity region is located substantially on a same plane as said another side, said electrode is formed overlapping with and facing each of said channel region and said third impurity region entirely, said insulation film is formed between said semiconductor layer and said electrode so as to come into contact with each of said semiconductor layer and said electrode, an impurity concentration of each of said third and fourth impurity regions is set lower than the impurity concentration of each of said first impurity region and said second impurity region, and higher than the impurity concentration of said channel region, the impurity concentration of said third impurity region is set to be different from the impurity concentration of said fourth impurity region, and a junction where there is a change in the impurity concentration of the third impurity region from the impurity concentration of the fourth impurity region is formed between the third impurity region and the fourth impurity region, wherein respective impurity concentrations throughout the third and fourth impurity regions are substantially constant.