Silicon carbide device with trench gate structure and method of manufacturing
A silicon carbide device includes a silicon carbide body with a trench gate structure that extends from a first surface into the silicon carbide body. A body region is in contact with an active sidewall of the trench gate structure. A source region is in contact with the active sidewall and located between the body region and the first surface. The body region includes a first body portion directly below the source region and distant from the active sidewall. In at least one horizontal plane parallel to the first surface, a dopant concentration in the first body portion is at least 150% of a reference dopant concentration in the body region at the active sidewall and a horizontal extension of the first body portion is at least 20% of a total horizontal extension of the body region.
1. A method of manufacturing a silicon carbide device, the method comprising:
providing a silicon carbide body;
forming a trench gate structure that extends from a first surface into the silicon carbide body;
forming a body region and a source zone, wherein after forming the trench gate structure, the body region and the source zone, the body region and the source zone are in contact with an active sidewall of the trench gate structure, wherein the source zone is located between the body region and the first surface;
forming a body enhancement implant mask on the first surface, wherein the body enhancement implant mask covers at least a first source portion of the source zone, wherein an opening in the body enhancement implant mask exposes at least a body contact area of the first surface, wherein the first source portion adjoins the active sidewall;
implanting dopants into a first body portion of the body region through the opening in the body enhancement implant mask, wherein the first body portion is located directly below the source zone and distant from the active sidewall, wherein in at least one horizontal plane, a dopant concentration in the first body portion is at least 150% of a reference dopant concentration in the body region at the active sidewall and a horizontal extension of the first body portion is at least 20% of a total horizontal extension of the body region; and
forming a shielding region of a conductivity type of the body region and extending from the first surface into the silicon carbide body, wherein the shielding region laterally directly adjoins the source region and the body region, and wherein the shielding region is in contact with an inactive sidewall of a further trench gate structure.
2. The method of claim 1 , wherein the dopants are implanted into the first body portion prior to forming the trench gate structure.
3. The method of claim 1 , wherein an implant axis for implanting the dopants into the first body portion is tilted with respect to a vertical direction of the first surface, and wherein the dopants are directed into a direction of the active sidewall of the trench gate structure.
4. The method of claim 3 , wherein an implant angle between the implant axis and the vertical direction is at least 3° in absolute value.
5. The method of claim 1 ,
wherein the body contact area laterally directly adjoins the source zone.
6. The method of claim 1 , wherein the opening in the body enhancement implant mask exposes a second source portion of the source zone, and wherein the second source portion is located between the body contact area and the first source portion.
7. The method of claim 1 , further comprising:
forming a body contact implant mask on the first surface, wherein the body contact implant mask covers the source zone, wherein an opening in the body contact implant mask exposes the body contact area;
implanting dopants of the conductivity type of the body region through the opening in the body contact implant mask; and
laterally recessing the body contact implant mask, wherein a laterally recessed body contact implant mask forms the body enhancement implant mask.
8. The method of claim 1 , further comprising:
forming a deep implant mask on the first surface, wherein the deep implant mask covers a third source portion of the source zone, wherein an opening in the deep implant mask exposes a fourth source portion of the source zone, wherein the fourth source portion is located between the body contact area and the third source portion; and
implanting dopants of the conductivity type of the body region through the opening in the deep implant mask.
9. The method of claim 8 , further comprising:
laterally recessing the deep implant mask, wherein a laterally recessed deep implant mask forms the body enhancement implant mask.
10. The method of claim 8 , further comprising:
forming a body contact implant mask on the first surface, wherein the body contact implant mask covers the source zone, and wherein an opening in the body contact implant mask exposes the body contact area, implanting dopants of the conductivity type of the body region through the opening in the body contact implant mask; and
laterally recessing the body contact implant mask to provide a laterally recessed body contact implant mask, wherein the laterally recessed body contact implant mask forms the deep implant mask.
11. The method of claim 1 , further comprising:
implanting dopants of a conductivity type complementary to a conductivity type of the body region into the source zone to form a doped source region in the source zone.
12. The method of claim 1 , wherein in the at least one horizontal plane, the horizontal extension of the first body portion is at least 50% of the total horizontal extension of the body region.