Semiconductor device and method for producing same
It is an object to improve the breakdown voltage characteristics of a vertical semiconductor device having an opening and including a channel formed of two-dimensional electron gas in the opening. The vertical semiconductor device includes a GaN-based stacked layer 15 having an opening 28 and the GaN-based stacked layer 15 includes n-type GaN-based drift layer 4 /p-type GaN-based barrier layer 6 /n-type GaN-based contact layer 7 . The vertical semiconductor device includes a regrown layer 27 located so as to cover the opening, the regrown layer 27 including an electron drift layer 22 and an electron supply layer 26 , a source electrode S, and a gate electrode G located on the regrown layer. The gate electrode G covers a portion having a length corresponding to the thickness of the p-type GaN-based barrier layer and is terminated at a position on the wall surface, the position being away from the bottom portion of the opening.
1. A vertical semiconductor device including a GaN-based stacked layer having an opening,
the GaN-based stacked layer including n-type GaN-based drift layer/p-type GaN-based barrier layer/n-type GaN-based contact layer in that order, the opening extending from a top layer and reaching the n-type GaN-based drift layer, the semiconductor device comprising:
a regrown layer located so as to cover a wall surface and a bottom portion of the opening, the regrown layer including an electron drift layer and an electron supply layer;
a source electrode that is in contact with the n-type GaN-based contact layer and the regrown layer around the opening; and
a gate electrode located on the regrown layer and having a terminal portion in the opening,
wherein the gate electrode covers a portion of a wall surface of the regrown layer, the portion of the wall surface of the regrown layer being in contact with the p-type barrier layer in the opening, and the gate electrode is terminated at the terminal portion on the wall surface, the terminal portion of the gate electrode being away from a bottom portion of the regrown layer that covers the bottom portion of the opening.
2. The semiconductor device according to claim 1 , further comprising a field plate electrode in the bottom portion of the regrown layer, the field plate electrode being located so as to cover at least a ridge at which the wall surface and bottom portion of the regrown layer intersect each other and so as to be away from the gate electrode.
3. The semiconductor device according to claim 2 , further comprising an insulating film disposed between the bottom portion of the regrown layer and the field plate electrode.
4. The semiconductor device according to claim 3 , further comprising an insulating layer disposed on the regrown layer and below the gate electrode.
5. The semiconductor device according to claim 1 , further comprising an insulating layer disposed on the regrown layer and below the gate electrode.
6. The semiconductor device according to claim 1 , wherein the opening has an outwardly slanted wall surface and, in a plan view, the terminal portion of the gate electrode lies outside a ridge at which the bottom portion and the wall surface of the opening intersect each other.
7. The semiconductor device according to claim 1 , wherein the gate electrode does not cover the bottom portion of the regrown layer that covers the bottom portion of the opening.