Semiconductor device and method for fabricating the same
In the structure of a semiconductor device of the present invention, a first source electrode is connected to a conductive substrate through a via hole, and a second source electrode is formed. Thus, even if a high reverse voltage is applied between a gate electrode and a drain electrode, electric field concentration likely to occur at an edge of the gate electrode closer to the drain electrode can be effectively dispersed or relaxed. Moreover, the conductive substrate is used as a substrate for forming element formation layers, so that a via hole penetrating the substrate to reach the backside thereof does not have to be formed in the conductive substrate. Thus, with the strength necessary for the conductive substrate maintained, the first source electrode can be electrically connected to a backside electrode.
1. A semiconductor device comprising:
a conductive layer;
a channel layer made of III-V nitride semiconductor and formed on or over the conductive layer;
a Schottky layer made of III-V nitride semiconductor and formed on the channel layer;
a first source electrode, a drain electrode, and a gate electrode formed on different parts of the Schottky layer, respectively;
a second source electrode connected to the first source electrode; and
an interconnect member connecting the first source electrode to the conductive layer through a groove penetrating the channel layer and the Schottky layer.
2. The device of claim 1 ,
wherein the conductive layer is a conductive substrate, and
the device further comprises a buffer layer interposed between the conductive substrate and the channel layer.
3. The device of claim 1 , further comprising:
an insulator substrate or a semiconductor substrate provided below the conductive layer; and
a buffer layer interposed between the substrate and the conductive layer or between the conductive layer and the channel layer.
4. The device of claim 1 ,
wherein the gate electrode is provided in a region interposed between the first source electrode and the drain electrode, and
the second source electrode extends from a region above the first source electrode toward a region above the drain electrode.
5. The device of claim 4 ,
wherein a portion of the second source electrode extending from the region above an edge of the gate electrode closer to the drain toward the region above the drain electrode has a length of 20% or more of the distance between the gate electrode and the drain electrode.
6. The device of claim 1 ,
wherein the gate electrode has a T-shaped cross section including: a stem in contact with the Schottky layer; and a top wider than the stem.
7. The device of claim 1 ,
wherein a metal in ohmic contact with the conductive layer is formed between the bottom surface of the groove and the interconnect member.
8. The device of claim 7 ,
wherein the metal is formed in a single layer, a stack of layers, or an alloy containing at least one of aluminum, titanium, gold, germanium, and antimony.
9. The device of claim 7 ,
wherein the Schottky layer is made of a material different from the conductive layer,
the metal is made of a material different from the first source electrode, and
the first source electrode is in ohmic contact with the Schottky layer.
10. The device of claim 9 , wherein the metal is made of the same material as the interconnect member.
11. The device of claim 9 , wherein the first source electrode is made of a material different from the interconnect member.
12. The device of claim 11 , wherein the second source electrode is made of a material different from the interconnect member.
13. The device of claim 4 , wherein the first source electrode is made of a material different from the second source electrode.
14. The device of claim 9 , wherein the first source electrode is not formed directly above the groove.