Shaping of brittle materials with controlled surface and bulk properties

Abstract

Methods of and devices for forming edge chamfers and through holes and slots on a material that is machined using a laser, such as an ultrafast laser. The shaped material has predetermined and highly controllable geometric shape and/or surface morphology. Further, a method of and a device for preventing re-deposition of the particles on a material that is machined using a laser, such as an ultrafast laser. A fluid is used to wash off the particles generated during the laser machining process. The fluid can be in a non-neutral condition, with one or more chemical salts added, or a condition allowing the coagulation of the particles in the fluid, such that the particles can be precipitated to avoid the reattachment to the machined substrate.

What is claimed is: 
     
         1 . An apparatus for laser processing a stock of brittle material, the stock of brittle material having a front surface and an opposite back surface, the apparatus comprising:
 a material holder for supporting the stock of brittle material;   a fluid reservoir holding a liquid solution and positioned such that the back surface of the stock of brittle material is contact with the liquid solution, the liquid solution having a zeta potential of less than about 10 mV; and   a laser generating pulsed laser beam, said pulses being in the picosecond or femtosecond range, and with the focus of the laser beam being adjustable such that during processing, the laser beam is incident on the front surface of the stock of brittle material and wherein the focus of the laser beam is initially at the back surface of the stock of brittle material and then the focus is moved towards the front surface of the stock of brittle material in order to removed material from the stock of brittle material by ablation, the material removed by ablation being in the form of debris particles, the liquid solution coagulating the debris particles in the liquid solution, the liquid solution thereby preventing the material removed by ablation from reattaching to the stock of brittle material.   
     
     
         2 . The apparatus of  claim 1 , wherein the liquid solution includes a salt. 
     
     
         3 . The apparatus of  claim 2 , wherein the salt is any one of CaCl 2 , MgCl 2 , and NaCl, or a combination thereof. 
     
     
         4 . The apparatus of  claim 2 , wherein the salt is a divalent salt. 
     
     
         5 . The apparatus of  claim 1 , wherein the liquid solution has a non-neutral pH value. 
     
     
         6 . The apparatus of  claim 1 , wherein the liquid solution has a pH value lower than 5. 
     
     
         7 . The apparatus of  claim 1 , wherein the debris particles removed by ablation are one of nanoparticles and microparticles, or a combination thereof. 
     
     
         8 . The apparatus of  claim 1 , wherein the material removed by ablation is colloidal silica. 
     
     
         9 . The apparatus of  claim 1 , wherein the laser beam is scanned along a tool path, the focused laser beam removing material from the stock of brittle material along the tool path. 
     
     
         10 . The apparatus of  claim 9 , wherein a second laser beam is directed onto the stock of brittle material, the second laser beam following the tool path and causing a controlled separation of the stock of brittle material into at least two portions of brittle material. 
     
     
         11 . The apparatus of  claim 1 , wherein the laser pulses are in the picosecond range. 
     
     
         12 . The apparatus of  claim 1 , wherein the laser pulses are in the femtosecond range. 
     
     
         13 . The apparatus of  claim 1 , wherein the laser processing forms a through hole or slot in the stock of brittle material. 
     
     
         14 . The apparatus of  claim 13 , wherein the through hole or slot has a chamfer. 
     
     
         15 . The apparatus of  claim 13 , wherein the through hole or slot has edges that are round in shape, the round shape having a radius of curvature. 
     
     
         16 . The apparatus of  claim 1 , wherein the stock of brittle material comprises a multiple layered structure of brittle material. 
     
     
         17 . The apparatus of the  claim 16 , wherein the laser beam is focused on one layer of the multiple layered structure of brittle material. 
     
     
         18 . The apparatus of  claim 1 , wherein the stock of brittle material is made of glass. 
     
     
         19 . The apparatus of  claim 1 , wherein the stock of brittle material is made of a consumer electronic protective glass. 
     
     
         20 . The apparatus of  claim 1 , wherein the stock of brittle material is made of sapphire.