Method of material processing by laser filamentation

摘要

A method is provided for the internal processing of a transparent substrate in preparation for a cleaving step. The substrate is irradiated with a focused laser beam that includes pulses having an energy and pulse duration selected to produce a filament within the substrate. The substrate is translated relative to the laser beam to irradiate the substrate and produce an additional filament at one or more additional locations. The resulting filaments form an array defining an internally scribed path for cleaving the substrate. Laser beam parameters may be varied to adjust the filament length and position, and to optionally introduce V-channels or grooves. The laser pulses may be delivered in a burst train for lowering the energy threshold for filament formation, increasing filament length, thermally annealing of the filament modification zone to minimize collateral damage, and increasing the processing speed compared with the use of low repetition rate lasers.

主权项

1. A method of preparing a substrate for cleavage, the method comprising the steps of:
irradiating the substrate with a burst of pulses of a focused laser beam, wherein the substrate is transparent to the focused laser beam, wherein a time delay between successive pulses in the burst of pulses is less than a time duration over which relaxation of one or more material modification dynamics occurs, and wherein the burst of pulses have an energy and pulse duration selected to produce a filament within the substrate; translating the substrate relative to the focused laser beam to irradiate the substrate and produce an additional filament at one or more additional locations; wherein the filaments form an array defining an internally scribed path for cleaving the substrate; wherein each burst of pulses is focused to provide a sufficient beam intensity within the substrate to cause self-focusing of the focused laser beam over an extended laser interaction focal volume, thereby producing a plasma channel while avoiding optical breakdown, such that substantially uniform modification of the material occurs along the beam path, thereby forming a single continuous filament within the substrate; and wherein each single continuous filament is formed with a sufficient length to facilitate cleavage of the substrate without requiring repeat passes of the laser over the same region.