Homoepitaxial growth of sic on low off-axis sic wafers
AssigneeNorstel AB
InventorsAlexandre Ellison, Christer Hallin, Bjorn Magnusson, Peder Bergman
Life of this patent
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Abstract
A wafer including a SiC substrate having a surface that is inclined relative to a (0001) basal plane at an angle higher than 0.1 degree but less than 1 degree, a SiC homoepitaxial device layer, and a SiC homoepitaxial boundary layer having a thickness up to 1 μm arranged between the substrate and the device layer. The boundary layer has been grown on the substrate under an atmosphere of lower supersaturation than when forming the device layer and at a C/Si ratio above 1.
Claims13
1-21. (canceled)
An SiC wafer produced according to a method comprising:
- growing SiC homoepitaxial layers on a surface of an SiC substrate, wherein the layers have a same polytype as the substrate, and wherein the surface is inclined relative to a (0001) basal plane at an angle higher than 0.1 degree but less than 1 degree;
- starting an homoepitaxial growth by forming a boundary layer with a thickness up to 1 μm;
- and
- forming a homoepitaxial device layer wherein the boundary layer is formed in an atmosphere of lower supersaturation than when forming the homoepitaxial device layer and at a C/Si ratio above 1,
- wherein the SiC wafer comprises an epitaxied bipolar device structure, wherein the wafer further comprises a buffer layer between the boundary layer and a low doped drift layer of the device structure and a thickness of the buffer layer is at least equal to a tangent of an off-axis angle between the wafer surface and the (0001) basal plane times a width of the device along an off-axis direction.
A wafer, comprising:
- a SiC substrate having a surface that is inclined relative to a (0001) basal plane at an angle higher than 0.1 degree but less than 1 degree;
- a SiC homoepitaxial device layer;
- and
- a SiC homoepitaxial boundary layer having a thickness up to 1 μm arranged between the substrate and the device layer, wherein the boundary layer has been grown on the substrate under an atmosphere of lower supersaturation than when forming the device layer and at a C/Si ratio above 1.
An SiC wafer, comprising:
- an Sic substrate;
- SiC homoepitaxial layers on a surface of the SiC substrate, wherein the layers have a same polytype as the substrate, and wherein the surface of the substrate is inclined relative to a (0001) basal plane at an angle higher than 0.1 degree but less than 1 degree;
- an epitaxied bipolar device structure;
- a buffer layer between the boundary layer and a low doped drift layer of the device structure, wherein a thickness of the buffer layer is at least equal to a tangent of an off-axis angle between the wafer surface and the (0001) basal plane times a width of the device along an off-axis direction;
- a boundary layer having a thickness up to 1 μm;
- and
- a homoepitaxial device layer.
Dependencies are inferred from the claim text.