Patent attributes
A method for processing a crystalline substrate to form multiple patterns of subsurface laser damage facilitates subsequent fracture of the substrate to yield first and second substrate portions of reduced thickness. Multiple (e.g., two, three, or more) groups of parallel lines of multiple subsurface laser damage patterns may be sequentially interspersed with one another, with at least some lines of different groups not crossing one another. Certain implementations include formation of multiple subsurface laser damage patterns including groups of parallel lines that are non-parallel to one another, but with each line remaining within ±5 degrees of perpendicular to the <1120> direction of a hexagonal crystal structure of a material of the substrate. Further methods involve formation of initial and subsequent subsurface laser damage patterns that are centered at different depths within an interior of a substrate, with the subsurface laser damage patterns being registered with one another and having vertical extents that are overlapping.
