Semiconductor device and method for fabricating the same
There is provided a semiconductor device and a method for fabricating the same whose withstanding characteristic may be enhanced and whose ON resistance may be reduced. A MIS-type HEMT includes a carrier traveling layer made of a group-III nitride semiconductor and formed on a supporting substrate, a carrier supplying layer made of a group-III nitride semiconductor and formed on the carrier traveling layer, source and drain electrodes formed on the carrier supplying layer, insulating films formed on the carrier supplying layer and a gate electrode formed on the insulating films. The insulating film is formed in a region interposed between the source and drain electrodes and has a trench whose cross-section is inverted trapezoidal and whose upper opening is wider than a bottom thereof. The gate electrode is formed at least from the bottom of the trench onto the insulating films on the side of the drain electrode.
1. A semiconductor device, comprising:
a carrier traveling layer formed on a supporting substrate and made of a group-III nitride semiconductor;
a carrier supplying layer formed on the carrier traveling layer and made of a group-III nitride semiconductor whose band gap energy is greater than that of the carrier traveling layer;
source and drain electrodes that ohmically contact with the carrier supplying layer;
an insulating film formed on the carrier supplying layer; and
a gate electrode formed on the insulating film;
wherein the insulating film includes a first trench formed in a region interposed between the source and the drain electrodes;
the first trench has a shape whose cross-section is inverted trapezoidal in which an upper opening is wider than a bottom thereof; and
the gate electrode is formed at least from the bottom of the first trench onto the insulating film on the side of the drain electrode.
2. The semiconductor device according to claim 1 , wherein the insulating film includes a first insulating film formed on the carrier supplying layer and having an aperture formed between the source and drain electrodes and a second insulating film that covers at least an upper surface of the carrier supplying layer exposed by the aperture; and
the bottom of the first trench is formed at least by a surface of the second insulating film formed within the aperture.
3. The semiconductor device according to claim 1 , wherein an angle formed between the respective sides of the first trench and the bottom thereof is 90 degrees or more.
4. The semiconductor device according to claim 1 , wherein the insulating film at least at the bottom of the first trench is a nitride film.
5. The semiconductor device according to claim 1 , further comprising:
an interlayer film formed on the insulating film; and
an electrode that contacts with the source electrode and whose part extends on the interlayer insulating film above the gate electrode.
6. The semiconductor device according to claim 1 , wherein the first trench reaches to the inside of the carrier traveling layer; and
the carrier traveling layer has a second trench formed on an upper side of the carrier traveling layer itself and the first trench includes the second trench under the first trench itself.