Patent ID: 11945049
Assignee: DISCO CORPORATION
Field: Measurement (Instruments)
Classification: CPC B  G  H | IPC B  G  H

Claim 2:
3. A SiC wafer manufacturing apparatus for manufacturing a SiC wafer from a SiC ingot having an end surface, the SiC wafer manufacturing apparatus comprising:
a laser beam, wherein the laser beam is applied to the SiC ingot in a condition where the focal point of the laser beam is set inside the SiC ingot at a predetermined depth from the end surface of the SiC ingot, the predetermined depth corresponding to the thickness of the SiC wafer to be manufactured, the laser beam having a transmission wavelength transmissible through SiC, thereby forming a separation layer inside the SiC ingot at the predetermined depth, the separation layer having a modified portion where SiC is separated into Si and C and cracks extending from the modified portion along a c-plane in the SiC ingot;
a separator, wherein the separator separates the SiC wafer from the SiC ingot along the separation layer;
a test laser beam, wherein the test laser beam is applied to the SiC ingot in a predetermined area in a condition where the focal point of the test laser beam is set inside the SiC ingot at the predetermined depth from the end surface of the SiC ingot, the predetermined depth corresponding to the thickness of the SiC wafer to be manufactured, the test laser beam having a transmission wavelength transmissible through SiC, thereby forming a test separation layer inside the SiC ingot at the predetermined depth, the test separation layer having a first test modified portion where SiC is separated into Si and C and first test cracks extending from the first test modified portion along the c-plane in the SiC ingot; and
a controller which controls a relative movement between the SiC ingot and the test laser beam in a direction perpendicular to a length of the first test modified portion, wherein the test laser beam forms a second test modified portion parallel to the first test modified portion and aligned therewith, thereby forming the second test modified portion inside the SiC ingot at the predetermined depth, the second test modified portion where SiC is separated into Si and C, wherein second test cracks extend from the second test modified portion along a c-plane in the SiC ingot;
wherein a verifying unit performs verification by changing a power of the test laser beam and setting the power of the test laser beam to a power at which the first and second test cracks are formed, such that the first and second test cracks overlap in the direction perpendicular to the length of the first test modified portion.