Off axis laser-based surface processing operations for semiconductor wafers
Systems and methods for laser-based surface processing operations on a semiconductor wafer, such as a silicon carbide semiconductor wafer, are provided. In one example, a method includes providing a semiconductor workpiece having a surface. The method includes providing emission of one or more lasers to the surface of a semiconductor workpiece at a non-perpendicular incidence angle relative to the surface. The method includes imparting relative motion between the one or more lasers and the semiconductor workpiece while providing emission of the one or more lasers to the surface of the semiconductor workpiece at the non-perpendicular incidence angle.
1. A method for processing a surface of a semiconductor wafer comprising:
providing a semiconductor workpiece having a surface:
providing emission of one or more lasers to the surface of a semiconductor workpiece at a non-perpendicular incidence angle relative to the surface;
imparting relative motion between the one or more lasers and the semiconductor workpiece while providing emission of the one or more lasers to the surface of the semiconductor workpiece at the non-perpendicular incidence angle;
wherein the surface comprises one or more step structures relative to a c-axis basal pane for the semiconductor workpiece; and
wherein imparting relative motion between the one or more lasers and the surface comprises imparting relative motion such that the one or more lasers scan the surface at a scan angle relative to a direction associated with a length of the one or more step structures.
2. The method of claim 1 , wherein the surface has a surface roughness of about 65 microns or greater.
3. The method of claim 1 , wherein providing emission of the one or more lasers reduces a thickness of the semiconductor workpiece by at least about 25 microns.
4. The method of claim 1 , wherein the semiconductor workpiece comprises an off-axis silicon carbide crystalline material.
5. The method of claim 1 , wherein imparting relative motion between the one or more lasers and the surface comprises imparting relative motion such that the one or more lasers scan the surface in a direction generally perpendicular to a direction associated with a length of the one or more step structures.
6. The method of claim 1 , wherein imparting relative motion between the one or more lasers and the surface comprises imparting relative motion such that the one or more lasers scan the surface in a direction that is not generally perpendicular to a direction associated with a length of the one or more step structures.
7. The method of claim 1 , wherein providing the semiconductor workpiece comprises separating the semiconductor workpiece from a boule using a removal process.
8. The method of claim 1 , wherein providing emission of one or more lasers to the surface of a semiconductor workpiece at a non-perpendicular incidence angle relative to the surface increases a fracture strength of the semiconductor workpiece.
9. The method of claim 1 , wherein the non-perpendicular incidence angle is about 75° or less.
10. The method of claim 1 , comprising obtaining data indicative of a workpiece property, wherein the method comprises adjusting the non-perpendicular incidence angle of the one or more lasers based on the data indicative of the workpiece property.
11. The method of claim 1 , wherein the method comprises adjusting a scan angle of the one or more lasers relative to one or more topographic features on the workpiece surface.
12. The method of claim 1 , wherein providing emission of the one or more lasers reduces a surface roughness of the surface to a range of about 0.5 nanometer to about 180 nanometers.
13. The method of claim 1 , wherein the semiconductor workpiece is a silicon carbide semiconductor wafer or a silicon carbide boule.
14. The method of claim 6 , wherein imparting relative motion between the one or more lasers and the surface comprises imparting relative motion such that the one or more lasers scan the surface in a direction generally parallel to a direction associated with a length of the one or more step structures.
15. The method of claim 6 , wherein imparting relative motion between the one or more lasers and the surface comprises imparting relative motion such that the one or more lasers scan the surface in a direction that comprises a range of about 20 degrees to about 70 degrees relative to a direction associated with a length of the one or more step structures.
16. The method of claim 6 , wherein the semiconductor workpiece comprises a laser-damage region resulting from removal of the semiconductor workpiece from a boule.
17. The method of claim 1 , wherein the one or more lasers have a spot size in a range of about 10 microns to about 25 mm.
18. The method of claim 1 , wherein the one or more lasers have a spot size such that there is about 0% to about 50% overlap of a scan dimension between passes of the one or more lasers.
19. The method of claim 1 , wherein the one or more lasers have a focal depth beneath the surface of the semiconductor workpiece.
20. The method of claim 1 , wherein providing emission of one or more lasers to the surface of a semiconductor workpiece at a non-perpendicular incidence angle relative to the surface comprises:
providing emission of one or more lasers at a first non perpendicular incidence angle; and
providing emission of one or more lasers at a second non perpendicular incidence angle, the second non-perpendicular incidence angle being different from the first non-perpendicular incidence angle.