IGBT WITH IMPROVED REVERSE BLOCKING CAPABILITY
An insulated gate bipolar transistor (IGBT) device. The IGBT may include a substrate layer, the substrate layer comprising a p-type dopant, a first epitaxial layer, disposed on the substrate layer, the first epitaxial layer comprising an N-type dopant having a first concentration. The IGBT may also include a second epitaxial layer, disposed on the first epitaxial layer, the second epitaxial layer comprising an N-type dopant having a second concentration, the second concentration being greater than the first concentration. The IGBT may further include a third epitaxial layer, disposed on the second epitaxial layer, the third epitaxial layer comprising an N-type dopant having a third concentration, the third concentration being less than the first concentration.
1 . An insulated gate bipolar transistor (IGBT) device, comprising:
a substrate layer, the substrate layer comprising a p-type dopant;
a first epitaxial layer, disposed on the substrate layer, the first epitaxial layer comprising an N-type dopant having a first concentration;
a second epitaxial layer, disposed on the first epitaxial layer, the second epitaxial layer comprising an N-type dopant having a second concentration, the second concentration being greater than the first concentration; and
a third epitaxial layer, disposed on the second epitaxial layer, the third epitaxial layer comprising an N-type dopant having a third concentration, the third concentration being less than the first concentration.
2 . The IGBT device of claim 1 , wherein the first epitaxial layer comprises a thickness of 10 micrometers or less.
3 . The IGBT device of claim 1 , wherein the second epitaxial layer comprises a thickness of 25 micrometers or less.
4 . The IGBT device of claim 1 , wherein the first epitaxial layer comprises a dopant concentration of 1×10 14 /cm 3 to 2×10 16 /cm 3 .
5 . The IGBT device of claim 1 , wherein the second epitaxial layer comprises a dopant concentration of 1×10 17 /cm 3 to 5×10 17 /cm 3 .
6 . The IGBT device of claim 1 , wherein a sheet resistance of the first epitaxial layer ranges from 0.3 Ωcm to 44.5 Ωcm.
7 . The IGBT device of claim 1 , wherein a sheet resistance of the second epitaxial layer ranges from 0.33 Ωcm to 0.086 Ωcm.
8 . An insulated gate bipolar transistor (IGBT) device, comprising:
a semiconductor substrate;
an emitter region, the emitter region disposed on a first side of the semiconductor substrate;
a substrate layer, the substrate layer disposed on a second side of the semiconductor substrate, opposite the first side, the substrate layer comprising a p-type dopant;
a drift layer, the drift layer comprising an N-type dopant and being disposed between the emitter region and the substrate layer; and
a buffer layer, disposed on the substrate layer, the buffer layer comprising an N-type dopant, wherein the buffer layer comprises a graded dopant profile, wherein a dopant concentration of the buffer layer increases with increasing distance from the substrate layer.
9 . The IGBT device of claim 8 , wherein the drift layer and the buffer layer are epitaxial layers.
10 . The IGBT device of claim 8 , wherein the buffer layer comprises a first average dopant concentration, wherein the drift layer comprises a second average dopant concentration, the second average dopant concentration being lower than the first average dopant concentration.
11 . The IGBT device of claim 8 , wherein the buffer layer comprises a thickness of 35 micrometers or less.
12 . The IGBT device of claim 8 , wherein the buffer layer comprises a minimum dopant concentration in a first region, the first region being adjacent and in contact with the substrate layer, and comprises a maximum dopant concentration in a second region, the second region not being in contact with the substrate layer,
wherein the minimum dopant concentration ranges from 1×10 14 /cm 3 to 2×10 16 /cm 3 , and wherein the maximum dopant concentration ranges from 1×10 17 /cm 3 to 5×10 17 /cm 3 .
13 . The IGBT device of claim 12 , wherein the first region comprises the graded dopant profile, and wherein the second region comprises a uniform dopant profile.
14 . A method of forming an insulated gate bipolar transistor (IGBT) device, comprising:
providing a substrate layer, the substrate layer comprising a p-type dopant;
forming a first epitaxial layer on the substrate layer, the first epitaxial layer comprising an N-type dopant having a first concentration;
forming a second epitaxial layer, disposed on the first epitaxial layer, the second epitaxial layer comprising an N-type dopant having a second concentration, the second concentration being greater than the first concentration; and forming
a third epitaxial layer, disposed on the second epitaxial layer, the third epitaxial layer comprising an N-type dopant having a third concentration, the third concentration being less than the first concentration.
15 . The method of claim 14 , wherein the first epitaxial layer comprises a thickness of 10 micrometers or less.
16 . The method of claim 14 , wherein the second epitaxial layer comprises a thickness of 25 micrometers or less.
17 . The method of claim 14 , wherein the second epitaxial layer comprises a thickness of 35 micrometers or less.
18 . The method of claim 14 , wherein the first epitaxial layer comprises a dopant concentration of 1×10 14 /cm 3 to 2×10 16 /cm 3 .
19 . The method of claim 14 , wherein the second epitaxial layer comprises a dopant concentration of 1×10 17 /cm 3 to 5×10 17 /cm 3 .
20 . The method of claim 14 , wherein the first epitaxial layer and the second epitaxial layer comprise a buffer layer, wherein the second epitaxial layer comprises a uniform dopant profile, and wherein the first epitaxial layer comprises a graded dopant profile, wherein a dopant concentration of the first epitaxial layer increases with increasing distance from the substrate layer.