Laser cutting of thermally tempered substrates

Abstract

Systems and methods for laser-cutting thermally tempered substrates are disclosed. In one embodiment, a method of separating a thermally tempered substrate includes directing a laser beam focal line such that at least a portion of the laser beam focal line is within a bulk of the thermally tempered substrate. The focused pulsed laser beam is pulsed to form a sequence of pulse bursts comprising one or more sub-pulses. The laser beam focal line produces a damage track within the bulk of the tempered substrate along the laser beam focal line. Relative motion is provided between the focused pulsed laser beam and the tempered substrate such that the pulsed laser beam forms a sequence of damage tracks within the tempered substrate. Individual damage tracks of the sequence of damage tracks are separated by a lateral spacing, and one or more microcracks connect adjacent damage tracks of the sequence of damage tracks.

What is claimed is: 
     
         1 . A thermally tempered glass substrate comprising:
 a first surface and a second surface, wherein the first surface and the second surface have a compressive stress greater than or equal to 24 MPa, and a stress profile within a body of the thermally tempered glass substrate between the first and second surface is parabolic;   an edge extending from the first surface to the second surface; and   a plurality of damage tracks positioned at the edge, wherein:
 each individual damage track of the plurality of damage tracks has a diameter of less than or equal to 5 μm and has a length of greater than or equal to 250 μm; 
 adjacent damage tracks of the plurality of damage tracks are separated by a lateral spacing between about 2 μm and about 20 μm; and 
 the plurality of damage tracks extend 50% or more of a length of the edge. 
   
     
     
         2 . The thermally tempered glass substrate of  claim 1 , wherein:
 each individual damage track of the plurality of damage tracks has a length equal to or greater than 1 mm; and   the plurality of damage tracks extend 75% or more of the length of the edge.   
     
     
         3 . The thermally tempered glass substrate of  claim 1 , wherein each individual damage track of the plurality of damage tracks has an internal diameter of <500 nm. 
     
     
         4 . The thermally tempered glass substrate of  claim 1 , wherein each of the plurality of damage tracks has an internal diameter of ≤400 nm. 
     
     
         5 . The thermally tempered glass substrate of  claim 1 , wherein each of the plurality of damage tracks has an internal diameter of ≤300 nm. 
     
     
         6 . The thermally tempered glass substrate of  claim 1 , wherein each individual damage track of the plurality of damage tracks has a length of about 1 mm to about 3 mm. 
     
     
         7 . The thermally tempered glass substrate of  claim 1 , wherein adjacent damage tracks of the plurality of damage tracks are separated by a lateral spacing between about 2 μm and about 15 μm. 
     
     
         8 . The thermally tempered glass substrate of  claim 1 , wherein each individual damage track of the plurality of damage tracks has a length of about 5 μm to about 10 μm. 
     
     
         9 . A system for processing a thermally tempered substrate, the system comprising:
 a laser source operable to emit a pulsed laser beam;   a translation table operable to receive the thermally tempered substrate and to be translated along at least one axis;   an optical assembly disposed within an optical path of the pulsed laser beam that transforms the pulsed laser beam into a laser beam focal line, wherein at least a portion of the laser beam focal line is operable to be positioned within a bulk of the thermally tempered substrate such that the laser beam focal line generates an induced multi-photon absorption within the thermally tempered substrate to produce a material modification within the thermally tempered substrate along the laser beam focal line; and   one or more controllers programmed to:
 pulse the pulsed laser beam to form a sequence of pulse bursts comprising one or more sub-pulses; and 
 control the translation table to provide relative motion between the pulsed laser beam and the thermally tempered substrate along the at least one axis in a first laser beam pass such that the pulsed laser beam forms a sequence of damage tracks within the thermally tempered substrate, wherein individual damage tracks of the sequence of damage tracks are separated by a lateral spacing, and one or more microcracks extend between adjacent damage tracks of the sequence of damage tracks. 
   
     
     
         10 . The system of  claim 9 , wherein:
 the pulsed laser beam has laser power between about 25 W and about 60 W;   each pulse bursts of the sequence of pulse bursts have between 2 and 25 sub-pulses; and   the lateral spacing between damage tracks is between about 2 μm and about 10 μm.