Semiconductor device and method for manufacturing the same
A semiconductor device according to an embodiment includes a first-conductivity-type SiC substrate, a first-conductivity-type SiC layer provided on the SiC substrate, having a first surface, and having a lower first-conductivity-type impurity concentration than the SiC substrate, first second-conductivity-type SiC regions provided in the first surface of the SiC layer, second second-conductivity-type SiC regions provided in the first SiC regions and having a higher second-conductivity-type impurity concentration than the first SiC region, silicide layers provided on the second SiC regions and having a second surface, a difference between a distance from the SiC substrate to the second surface and a distance from the SiC substrate to the first surface being equal to or less than 0.2 μm, a first electrode provided to contact with the SiC layer and the silicide layers, and a second electrode provided to contact with the SiC substrate.
1. A semiconductor device comprising:
a first-conductivity-type SiC substrate;
a first-conductivity-type SiC layer provided on the first-conductivity-type SiC substrate, the first-conductivity-type SiC layer having a first surface, the first-conductivity-type SiC layer having a lower first-conductivity-type impurity concentration than the first-conductivity-type SiC substrate;
a pair of first second-conductivity-type SiC regions provided at the first surface of the first-conductivity-type SiC layer;
a pair of second second-conductivity-type SiC regions each provided in each of the first second-conductivity-type SiC regions, the second second-conductivity-type SiC regions having a higher second-conductivity-type impurity concentration than the first second-conductivity-type SiC regions;
a pair of silicide layers each provided on each of the second second-conductivity-type SiC regions, the silicide layers having a second surface opposite to the second second-conductivity-type SiC region, a difference between a distance from the first-conductivity-type SiC substrate to the second surface and a distance from the first-conductivity-type SiC substrate to the first surface being equal to or greater than −0.1 μm and equal to or less than 0.1 μm;
a first electrode provided to contact with the first-conductivity-type SiC layer and the silicide layers; and
a second electrode provided to contact with the first-conductivity-type SiC substrate.
2. The device according to claim 1 , further comprising:
an insulating film provided between a side surface of each of the silicide layers and the first-conductivity-type SiC layer, the insulating film contacting the side surface.
3. The device according to claim 1 , wherein the silicide layers are nickel silicide layers.
4. The device according to claim 2 , wherein the insulating film is a silicon oxide film.
5. A semiconductor device comprising:
a first-conductivity-type SiC substrate;
a first-conductivity-type SiC layer provided on the first-conductivity-type substrate, the first-conductivity-type SiC layer having a first surface, the first-conductivity-type SiC layer having a lower first-conductivity-type impurity concentration than the first-conductivity-type SiC substrate;
a pair of first second-conductivity-type SiC regions provided at the first surface of the SiC layer;
a pair of second second-conductivity-type SiC regions provided in each of the first second-conductivity-type SiC regions, the second second-conductivity-type SiC regions having a higher second-conductivity-type impurity concentration than the first second-conductivity-type SiC region;
a plurality of silicide layers each provided on each of the second second-conductivity-type SiC regions, each of the silicide layers having a second surface opposite to the second second-conductivity-type SiC region;
a first electrode provided to contact with the first-conductivity-type SiC layer and the silicide layers; and
a second electrode provided to contact with the SiC substrate,
wherein a difference between a distance from the first-conductivity-type SiC substrate to the second surface and a distance from the first-conductivity-type SiC substrate to the first surface is equal to or greater than −0.1 μm and equal to or less than 0.1 μm.
6. The device according to claim 5 , wherein the silicide layers are nickel silicide layers.
7. A semiconductor device comprising:
a first-conductivity-type SiC substrate;
a first-conductivity-type SiC layer provided on the SiC substrate, the first-conductivity-type SiC layer having a first surface, the first-conductivity-type SiC layer having a lower first-conductivity-type impurity concentration than the first-conductivity-type SiC substrate;
a pair of first second-conductivity-type SiC regions provided in the first surface of the first-conductivity-type SiC layer;
a pair of second second-conductivity-type SiC regions each provided in each of the first second-conductivity-type SiC regions, the first second-conductivity-type SiC regions having a higher second-conductivity-type impurity concentration than the first second-conductivity-type SiC region;
a plurality of silicide layers provided on each of the second second-conductivity-type SiC regions, the silicide layers having a second surface opposite to the second second-conductivity-type SiC region;
a first electrode provided to contact with the first-conductivity-type SiC layer and the silicide layers; and
a second electrode provided to contact with the first-conductivity-type SiC substrate,
wherein a difference between a distance from the first-conductivity-type SiC substrate to the second surface and a distance from the first-conductivity-type SiC substrate to the first surface is equal to or greater than −0.1 μm and equal to or less than 0.1 μm.
8. The device according to claim 7 ,
wherein the silicide layers are nickel silicide layers.
9. A method for manufacturing a semiconductor device, comprising:
forming a first mask member on an first-conductivity-type SiC layer;
etching the first mask member to form an opening;
performing a first ion implantation process of implanting second-conductivity-type impurities into the SiC layer, using the first mask member as a mask;
forming, on the first mask member, a second mask member having a thickness less than half the width of the opening;
etching the second mask member to form a sidewall on a side surface of the opening;
etching the SiC layer, using the first mask member and the sidewall as a mask, to form a groove;
performing a second ion implantation process of implanting second-conductivity-type impurities into the SiC layer, using the first mask member and the sidewall as a mask;
forming a first metal film on the SiC layer;
performing a heat treatment to react the first metal film with the SiC layer, thereby forming a silicide layer;
removing the first metal film having not been reacted;
removing the first mask member and the sidewall; and
forming a second metal film on the SiC layer and the silicide layer.
10. The method according to claim 9 , wherein the metal film is a nickel film.
11. A method for manufacturing a semiconductor device, comprising:
forming a first mask member on an first-conductivity-type SiC layer;
etching the first mask member to form an opening;
etching the SiC layer, using the first mask member as a mask, to form a groove;
performing a first ion implantation process of implanting second-conductivity-type impurities into the SiC layer, using the first mask member as a mask;
forming, on the first mask member, a second mask member having a thickness less than half the width of the opening;
etching the second mask member to form a first sidewall on a side surface of the opening;
performing a second ion implantation process of implanting second-conductivity-type impurities into the SiC layer, using the first mask member and the first sidewall as a mask;
forming a first metal film on the SiC layer;
performing a heat treatment to react the first metal film with the SiC layer, thereby forming a silicide layer;
removing the first metal film having not been reacted;
removing the first mask member and a portion of the first sidewall to form a second sidewall on a side surface of the groove; and
forming a second metal film on the SiC layer and the silicide layer.
12. The method according to claim 11 , wherein the metal film is a nickel film.
13. A semiconductor device comprising:
a first-conductivity-type SiC substrate;
a first-conductivity-type SiC layer provided on the first-conductivity-type SiC substrate, the first-conductivity-type SiC layer having a first surface, the first-conductivity-type SiC layer having a lower first-conductivity-type impurity concentration than the first-conductivity-type SiC substrate;
a pair of first second-conductivity-type SiC regions provided at the first surface of the first-conductivity-type SiC layer;
a pair of second second-conductivity-type SiC regions each provided in each of the first second-conductivity-type SiC regions, the second second-conductivity-type SiC regions having a higher second-conductivity-type impurity concentration than the first second-conductivity-type SiC regions;
a pair of silicide layers each provided on each of the second second-conductivity-type SiC regions, the silicide layers having a second surface opposite to the second second-conductivity-type SiC region, a distance between the first surface and the second surface being equal to or less than 0.2 μm when taking a direction from the first-conductivity-type SiC substrate towards the first-conductivity-type SiC layer as positive direction;
a first electrode provided to contact with the first-conductivity-type SiC layer and the silicide layers; and
a second electrode provided to contact with the first-conductivity-type SiC substrate.
14. The device according to claim 13 , further comprising:
an insulating film provided between a side surface of each of the silicide layers and each of the first second-conductivity-type SiC regions.
15. The device according to claim 13 , wherein the distance is equal to or greater than −0.1 μm and equal to or less than 0.1 μm.