Silicon carbide epitaxial wafer, preparation method thereof and semiconductor device

Abstract

The invention belongs to the technical field of semiconductors, and discloses a silicon carbide epitaxial wafer, a preparation method thereof and a semiconductor device, and the method comprises the steps: growing a first epitaxial layer on the surface of one side of a silicon carbide substrate in a first cavity; growing a second epitaxial layer on the surface of one side, far away from the silicon carbide substrate, of the first epitaxial layer in the second cavity; growing a third epitaxial layer on the surface of one side, far away from the first epitaxial layer, of the second epitaxial layer in the second cavity; growing a fourth epitaxial layer on the surface of one side, far away from the second epitaxial layer, of the third epitaxial layer in the first cavity; and growing a fifth epitaxial layer on the surface of one side, far away from the third epitaxial layer, of the fourth epitaxial layer in the second cavity to obtain the silicon carbide epitaxial wafer, wherein the first epitaxial layer and the fourth epitaxial layer are N-type layers, and the second epitaxial layer, the third epitaxial layer and the fifth epitaxial layer are P-type layers. Therefore, the silicon carbide epitaxial wafer is high in quality and low in defect density and surface roughness, and the performance and yield of the device can be improved when the silicon carbide epitaxial wafer is applied to the ultrahigh-voltage power device.

Claims

1. A method for preparing a silicon carbide epitaxial wafer, characterized in that, Comprising: Growing a first epitaxial layer on one surface of a silicon carbide substrate in a first cavity; Growing a second epitaxial layer on one surface of the first epitaxial layer away from the silicon carbide substrate in a second cavity; Growing a third epitaxial layer on one surface of the second epitaxial layer away from the first epitaxial layer in the second cavity; Growing a fourth epitaxial layer on one surface of the third epitaxial layer away from the second epitaxial layer in the first cavity; Growing a fifth epitaxial layer on one surface of the fourth epitaxial layer away from the third epitaxial layer in the second cavity to obtain the silicon carbide epitaxial wafer; Wherein, the first epitaxial layer and the fourth epitaxial layer are N-type layers, and the second epitaxial layer, the third epitaxial layer, and the fifth epitaxial layer are P-type layers.

2. The method according to claim 1, characterized in that, Measuring the defect density, thickness, and doping concentration of the first epitaxial layer after growing the first epitaxial layer; and / or, Measuring the defect density, thickness, and doping concentration of the second epitaxial layer after growing the second epitaxial layer; and / or, Measuring the defect density, thickness, and doping concentration of the third epitaxial layer after growing the third epitaxial layer; and / or, Measuring the defect density, thickness, and doping concentration of the fourth epitaxial layer after growing the fourth epitaxial layer; and / or, Measuring the defect density, thickness, and doping concentration of the fifth epitaxial layer after growing the fifth epitaxial layer.

3. The method according to claim 1 or 2, characterized in that, The process parameters for growing the first epitaxial layer include: The flow rate of nitrogen is 40 sccm to 60 sccm, the growth temperature is 1580 °C to 1650 °C, the growth pressure is 160 mbar to 280 mbar, the growth time is 1200 s to 2500 s, and the growth rate is 5 μm×h -1 ~10 μm×h -1 .

4. The method according to claim 1 or 2, characterized in that The process parameters for growing the second epitaxial layer include: The flow rate of trimethylaluminum is 0.1 sccm to 0.13 sccm, the water bath temperature of trimethylaluminum is 19 °C to 20 °C, the growth temperature is 1600 °C to 1660 °C, the growth pressure is 50 mbar to 70 mbar, the growth time is 50 s to 70 s, and the growth rate is 80 μm×h -1 ~120 μm×h -1 .

5. The method according to claim 1 or 2, characterized in that, The process parameters for growing the third epitaxial layer include: The flow rate of trimethylaluminum is 0.0003 sccm to 0.0008 sccm, the water bath temperature of trimethylaluminum is 19°C to 20°C, the growth temperature is 1600°C to 1660°C, the growth pressure is 50 mbar to 70 mbar, the growth time is 3200 s to 3400 s, and the growth rate is 110 μm×h -1 ~120 μm×h -1 .

6. The method according to claim 1 or 2, characterized in that, The process parameters for growing the fourth epitaxial layer include: The flow rate of nitrogen is 50 sccm to 60 sccm, the growth temperature is 1580 °C to 1640 °C, the growth pressure is 180 mbar to 260 mbar, the growth time is 100 s to 200 s, and the growth rate is 60 μm×h -1 to 70 μm×h -1 .

7. The method according to claim 1 or 2, characterized in that The process parameters for growing the fifth epitaxial layer include: The feeding rate of trimethylaluminum is 6 sccm to 8 sccm, the water bath temperature of trimethylaluminum is 30 °C to 40 °C, the growth temperature is 1580 °C to 1620 °C, the growth pressure is 70 mbar to 90 mbar, the growth time is 120 s to 240 s, and the growth rate is 20 μm×h -1 ~40 μm×h -1 .

8. A silicon carbide epitaxial wafer, characterized in that, Prepared by using the method according to any one of claims 1 to 7.

9. The silicon carbide epitaxial wafer according to claim 8, wherein, The silicon carbide epitaxial wafer includes a first epitaxial layer, a second epitaxial layer, a third epitaxial layer, a fourth epitaxial layer, and a fifth epitaxial layer which are stacked, wherein the first epitaxial layer and the fourth epitaxial layer are N-type layers, and the second epitaxial layer, the third epitaxial layer, and the fifth epitaxial layer are P-type layers.

10. The silicon carbide epitaxial wafer according to claim 9, wherein The doping concentration of the first epitaxial layer is 1×10 18 atoms / cm 3 ~5×10 18 atoms / cm 3 ; the doping concentration of the second epitaxial layer is 1×10 16 atoms / cm 3 ~2×10 17 atoms / cm 3 ; the doping concentration of the third epitaxial layer is 1×10 14 atoms / cm 3 ~5×10 14 atoms / cm 3 ; the doping concentration of the fourth epitaxial layer is 5×10 16 atoms / cm 3 ~8×10 16 atoms / cm 3 ; the doping concentration of the fifth epitaxial layer is 1×10 19 atoms / cm 3 ~1×10 20 atoms / cm 3 .

11. The silicon carbide epitaxial wafer according to claim 9, wherein, The thickness of the first epitaxial layer is 1 μm to 5 μm, the thickness of the second epitaxial layer is 1 μm to 3 μm, the thickness of the third epitaxial layer is 100 μm to 110 μm, the thickness of the fourth epitaxial layer is 1 μm to 3 μm, and the thickness of the fifth epitaxial layer is 1 μm to 3 μm.

12. The silicon carbide epitaxial wafer according to claim 8 or 9, characterized in that, The defect density of the silicon carbide epitaxial wafer is ≤ 0.5 pcs / cm 2 .

13. The silicon carbide epitaxial wafer according to claim 8 or 9, characterized in that, The surface roughness of the silicon carbide epitaxial wafer is ≤ 0.5 nm.

14. A semiconductor device, characterized in that, Including a silicon carbide epitaxial wafer prepared by using the method according to any one of claims 1 to 7 or a silicon carbide epitaxial wafer according to any one of claims 8 to 13.

Images