Chamfered silicon carbide substrate and method of chamfering
The present invention relates to a chamfered silicon carbide substrate which is essentially monocrystalline, and to a corresponding method of chamfering a silicon carbide substrate. A silicon carbide substrate according to the invention comprises a main surface ( 102 ), wherein an orientation of said main surface ( 102 ) is such that a normal vector ({right arrow over (O)}) of the main surface ( 102 ) includes a tilt angle with a normal vector ({right arrow over (N)}) of a basal lattice plane ( 106 ) of the substrate, and a chamfered peripheral region ( 110 ), wherein a surface of the chamfered peripheral region includes a bevel angle with said main surface, wherein said bevel angle is chosen so that, in more than 75% of the peripheral region, normal vectors ({right arrow over (F)}_i) of the chamfered peripheral region ( 110 ) differ from the normal vector of the basal lattice plane by less than a difference between the normal vector of the main surface and the normal vector of the basal lattice plane of the substrate.
1. Silicon carbide substrate for epitaxially deposited layers which is essentially monocrystalline, the silicon carbide substrate being fabricated by slicing a bulk SiC crystal, wherein the silicon carbide substrate has a thickness of at least 200 μm and not more than 1000 μm, the silicon carbide substrate comprising:
a main surface ( 102 ), wherein an orientation of said main surface ( 102 ) is such that a normal vector ({right arrow over (O)}) of the main surface ( 102 ) includes a tilt angle in a range between 0.5° and 8° with a normal vector ({right arrow over (N)}) of a ( 0001 ) basal lattice plane ( 106 ) of the substrate, and
a bottom surface ( 104 ),
a first chamfered peripheral region ( 110 ) arranged on the main surface ( 102 ), and a second chamfered peripheral region arranged on the bottom surface ( 104 ), wherein a surface of the first chamfered peripheral region includes a constant bevel angle with said main surface, the constant bevel angle extending from the main surface to a distal end of the silicon carbide substrate, wherein the first chamfered peripheral region ( 110 ) is arranged around at least 95% of a circumference of the substrate, and wherein a surface of the second chamfered peripheral region includes a constant bevel angle with said bottom surface ( 104 ), the constant bevel angle extending from the bottom surface ( 104 ) to the distal end of the silicon carbide substrate, wherein the second chamfered peripheral region is arranged around at least 95% of a circumference of the substrate,
wherein, at least on the main surface ( 102 ), said constant bevel angle is chosen so that, in more than 75% of the chamfered peripheral region, the constant bevel angle, which is included by a normal vector ({right arrow over (F)}_t) of the chamfered peripheral region ( 110 ) and the normal vector ({right arrow over (O)}) of the main surface ( 102 ), is smaller than the tilt angle, which is included by the normal vector ({right arrow over (O)}) of the main surface ( 102 ) and the normal vector ({right arrow over (N)}) of the ( 0001 ) basal lattice plane of the substrate.
2. Silicon carbide substrate according to claim 1 , wherein a difference between the normal vector ({right arrow over (O)}) of the main surface and the normal vector ({right arrow over (N)}) of the ( 0001 ) basal lattice plane of the substrate is measured at a location ( 124 ) adjacent to the chamfered peripheral region.
3. Silicon carbide substrate according to claim 1 , wherein said substrate has a surface roughness of equal to or less than 10 nm on at least 80% of the chamfered peripheral region.
4. Silicon carbide substrate according claim 1 , wherein the substrate has a polytype selected from a group comprising 4H and 6H.
5. Silicon carbide substrate according to claim 1 , wherein the substrate has a diameter of at least 150±0.2 mm and/or a thickness of 350±25 μm.
6. A silicon carbide wafer substrate for epitaxially deposited layers which is essentially monocrystalline, wherein the silicon carbide wafer substrate has a thickness of at least 200 μm and not more than 1000 μm, the silicon carbide wafer substrate comprising:
a main surface ( 102 ), wherein an orientation of said main surface ( 102 ) is such that a normal vector ({right arrow over (O)}) of the main surface ( 102 ) includes a tilt angle in a range between 0.5° and 8° with a normal vector ({right arrow over (N)}) of a ( 0001 ) basal lattice plane ( 106 ) of the substrate,
a bottom surface ( 104 ),
a first chamfered peripheral region ( 110 ) arranged on the main surface ( 102 ); and
a second chamfered peripheral region arranged on the bottom surface ( 104 ),
the first chamfered peripheral region ( 110 ) comprising a surface having a single, constant bevel angle extending from the main surface to a distal end of the silicon carbide substrate, wherein the chamfered peripheral region ( 110 ) is arranged around at least 95% of a circumference of the substrate,
the second chamfered peripheral region comprising a surface having a constant bevel angle with said bottom surface ( 104 ), the constant bevel angle extending from the bottom surface ( 104 ) to the distal end of the silicon carbide substrate, wherein the second chamfered peripheral region is arranged around at least 95% of a circumference of the substrate,
wherein, at least on the main surface ( 102 ), said constant bevel angle is chosen so that, in more than 75% of the chamfered peripheral region, the constant bevel angle, which is included by a normal vector ({right arrow over (F)}_t) of the chamfered peripheral region ( 110 ) and the normal vector ({right arrow over (O)}) of the main surface ( 102 ), is smaller than the tilt angle, which is included by the normal vector ({right arrow over (O)}) of the main surface ( 102 ) and the normal vector ({right arrow over (N)}) of the ( 0001 ) basal lattice plane of the substrate.