Nitride semiconductor device and method for manufacturing same

Abstract

According to one embodiment, a nitride semiconductor device includes a first semiconductor layer, a second semiconductor layer, a first electrode, a second electrode, a third electrode, a first insulating film and a second insulating film. The first semiconductor layer includes a nitride semiconductor. The second semiconductor layer is provided on the first layer, includes a nitride semiconductor, and includes a hole. The first electrode is provided in the hole. The second electrode is provided on the second layer. The third electrode is provided on the second layer so that the first electrode is disposed between the third and second electrodes. The first insulating film is provided between the first electrode and an inner wall of the hole and between the first and second electrodes, and is provided spaced from the third electrode. The second insulating film is provided in contact with the second layer between the first and third electrodes.

1 . A nitride semiconductor device comprising:
 a first semiconductor layer including a nitride semiconductor;   a second semiconductor layer provided on a part of the first semiconductor layer, including a nitride semiconductor having a band gap wider than a band gap of the first semiconductor layer, and including a hole;   a first electrode provided in the hole;   a second electrode provided on the second semiconductor layer and electrically connected to the second semiconductor layer;   a third electrode provided on the second semiconductor layer so that the first electrode is disposed between the third electrode and the second electrode, the third electrode being electrically connected to the second semiconductor layer;   a first insulating film including oxygen, provided between the first electrode and an inner wall of the hole and between the first electrode and the second electrode, and provided spaced from the third electrode; and   a second insulating film including nitrogen and provided in contact with the second semiconductor layer between the first electrode and the third electrode.   
     
     
         2 . The device according to  claim 1 , wherein the first insulating film is in contact with the second semiconductor layer. 
     
     
         3 . The device according to  claim 1 , wherein the first electrode is provided so as to cover an end of the first insulating film on a side of the third electrode. 
     
     
         4 . The device according to  claim 1 , further comprising a fourth electrode electrically connected to the first electrode and covering an end of the first insulating film on a side of the third electrode. 
     
     
         5 . The device according to  claim 1 , wherein the first insulating film includes silicon oxide. 
     
     
         6 . The device according to  claim 1 , wherein the second insulating film includes silicon nitride. 
     
     
         7 . The device according to  claim 1 , wherein
 the first semiconductor layer includes Al X Ga 1-X N (0≦X≦1) and   the second semiconductor layer includes Al Y Ga 1-Y N (0≦Y≦1, X≦Y).   
     
     
         8 . The device according to  claim 1 , wherein the first semiconductor layer includes a channel in a normally OFF transistor. 
     
     
         9 . The device according to  claim 1 , wherein
 the first electrode is a gate electrode of a transistor,   the second electrode is a source electrode of the transistor, and   the third electrode is a drain electrode of the transistor.   
     
     
         10 . A nitride semiconductor device comprising:
 a first semiconductor layer including a nitride semiconductor;   a second semiconductor layer provided on a part of the first semiconductor layer, including a nitride semiconductor having a band gap wider than a band gap of the first semiconductor layer, and including a hole;   a first electrode provided in the hole;   a second electrode provided on the second semiconductor layer and electrically connected to the second semiconductor layer;   a third electrode provided on the second semiconductor layer so that the first electrode is disposed between the third electrode and the second electrode, the third electrode being electrically connected to the second semiconductor layer;   a first insulating film including oxygen and provided in contact with the second semiconductor layer between the first electrode and an inner wall of the hole and between the first electrode and the second electrode; and   a second insulating film including nitrogen and provided in contact with the second semiconductor layer between the first electrode and the third electrode.   
     
     
         11 . The device according to  claim 10 , wherein the first insulating film includes silicon oxide. 
     
     
         12 . The device according to  claim 10 , wherein the second insulating film includes silicon nitride. 
     
     
         13 . The device according to  claim 10 , wherein the first semiconductor layer includes Al X Ga 1-X N (0≦X≦1) and
 the second semiconductor layer includes Al Y Ga 1-Y N (0≦Y≦1, X≦Y). 
 
     
     
         14 . The device according to  claim 10 , wherein the first semiconductor layer includes a channel in a normally OFF transistor. 
     
     
         15 . The device according to  claim 10 , wherein
 the first electrode is a gate electrode of a transistor,   the second electrode is a source electrode of the transistor, and   the third electrode is a drain electrode of the transistor.   
     
     
         16 . A method for manufacturing a nitride semiconductor device comprising:
 forming a first semiconductor layer including a nitride semiconductor on a support substrate and forming a second semiconductor layer having a band gap wider than a band gap of the first semiconductor layer and including a nitride semiconductor on the first semiconductor layer;   forming a second insulating film including nitrogen on the second semiconductor layer;   forming a hole by removing parts of the second insulating film and the second semiconductor layer;   forming a first insulating film including oxygen so as to cover an inner wall of the hole and the second insulating film;   removing at least a part of the first insulating film on one side as viewed from the hole;   forming a second electrode electrically connected to the second semiconductor layer on another side as viewed from the hole and forming a third electrode electrically connected to the second semiconductor layer on the one side as viewed from the hole spaced from the first insulating film; and   forming a first electrode in the hole via the first insulating film.   
     
     
         17 . A method for manufacturing a nitride semiconductor device comprising:
 forming a first semiconductor layer including a nitride semiconductor on a support substrate and forming a second semiconductor layer having a band gap wider than a band gap of the first semiconductor layer and including a nitride semiconductor on the first semiconductor layer;   forming a second insulating film including nitrogen on the second semiconductor layer;   forming a hole by removing a part of the second insulating film and removing a part of a portion of the second semiconductor layer where the second insulating film is removed;   forming a first insulating film including oxygen so as to cover an inner wall of the hole, the second insulating film provided on one side as viewed from the hole, and the second semiconductor layer provided on another side as viewed from the hole;   forming a third electrode electrically connected to the second semiconductor layer on the one side as viewed from the hole and forming a second electrode electrically connected to the second semiconductor layer on the another side as viewed from the hole; and   forming a first electrode in the hole via the first insulating film.