| 摘要 |
PROBLEM TO BE SOLVED: To improve characteristics of a normally-off semiconductor device using a nitride semiconductor.SOLUTION: A semiconductor device includes: a channel layer CH, a barrier layer BA, an insulation film IF1 and an insulation film IF2 which are formed on a substrate S; a trench T which pierces the insulation film IF2, the insulation film IF1 and the barrier film BA to reach the middle of the channel layer CH; and a gate electrode GE arranged in the trench T and on the insulation film IF2 via gate insulation film GI. The band gap of the insulation film IF2 is smaller than the band gap of the insulation film IF1, and the band gap of the insulation film IF2 is smaller than the band gap of the gate insulation film GI. With this composition, charge (electron) can be accumulated in the insulation film IF2 in an upper layer thereby to improve field intensity at the corner of the trench. As a result, even at the corner of the trench, a channel is successfully formed to reduce on-resistance thereby to increase on-state current.SELECTED DRAWING: Figure 1 |
