Semiconductor device and method for manufacturing semiconductor device
A semiconductor device includes a first electrode, a silicon carbide substrate having a first surface electrically connected with the first electrode and a second surface opposite to the first surface, an ohmic junction layer disposed on the second surface, and a second electrode disposed on the ohmic junction layer. The ohmic junction layer has a first layer that is directly disposed on the second surface and includes a first silicide of titanium and a first silicide of a metal element other than titanium, and a second layer that is directly disposed on the first layer, includes a second silicide of titanium and a second silicide of the metal element, and has a lower titanium concentration than the first layer.
1. A semiconductor device comprising:
a first electrode;
a silicon carbide substrate having a first surface electrically connected with the first electrode, and a second surface opposite to the first surface;
an ohmic junction layer disposed on the second surface; and
a second electrode disposed on the ohmic junction layer, wherein the ohmic junction layer comprises
a first layer that is directly disposed on the second surface and includes a first silicide of titanium and a first silicide of a metal element other than titanium, and
a second layer that is directly disposed on the first layer, includes a second silicide of titanium and a second silicide of the metal element, and has a lower titanium concentration than the first layer.
2. The semiconductor device according to claim 1 , wherein the metal element in the second layer has a concentration higher than that of the metal element in the first layer.
3. The semiconductor device according to claim 1 , wherein each of the first layer and second layer includes carbon, and carbon in the first layer has a concentration higher than that of carbon in the second layer.
4. The semiconductor device according to claim 1 , wherein silicon in the second layer has a concentration higher than that of silicon in the first layer.
5. The semiconductor device according to claim 1 , wherein the metal element has a melting point lower than that of titanium.
6. The semiconductor device according to claim 1 , wherein the metal element includes at least one from among nickel, molybdenum, tantalum, tungsten, palladium and cobalt.
7. A method for manufacturing a semiconductor device, comprising steps of:
providing a substrate structure that includes a first electrode, and a silicon carbide substrate having a first surface electrically connected to the first electrode, and having a second surface opposite to the first surface;
forming a titanium layer on the second surface of the silicon carbide substrate;
forming a metal element layer including a metal element other than titanium that is bondable with silicon to form a silicide, on the titanium layer;
irradiating the metal element layer with laser light to form an ohmic junction layer having
a first layer that includes a first silicide of titanium and a first silicide of the metal element other than titanium, directly disposed on the second surface of the silicon carbide substrate, and
a second layer that includes a second silicide of titanium and a second silicide of the metal element, directly disposed on the first layer, the second layer having a lower titanium concentration than the first layer; and
forming a second electrode on the ohmic junction layer.
8. The method according to claim 7 , wherein the metal element in the second layer has a concentration higher than that of the metal element in the first layer.
9. The method according to claim 7 , wherein each of the first layer and second layer includes carbon, and carbon in the first layer has a concentration higher than that of carbon in the second layer.
10. The method according to claim 7 , wherein silicon in the second layer has a concentration higher than that of silicon in the first layer.
11. The method according to claim 7 , wherein the metal element has a melting point lower than that of titanium.
12. The method according to claim 7 , wherein the metal element includes at least one from among nickel, molybdenum, tantalum, tungsten, palladium and cobalt.