Liquid-assisted laser micromachining of transparent dielectrics

Abstract

A method for forming features in transparent dielectric materials is described. The method includes laser micromachining of a transparent dielectric material. The transparent dielectric material is in contact with a liquid containing a fluorinated compound. Features formed by the method have low surface roughness and highly uniform linear dimensions.

What is claimed is: 
     
         1 . A method of processing a transparent dielectric material, comprising:
 focusing a laser beam to a focal point in a liquid, the liquid directly contacting a working surface of a transparent dielectric material, the liquid comprising a fluorinated compound.   
     
     
         2 . The method of  claim 1 , wherein the focusing includes forming the laser beam with a laser system, the laser system comprising a laser source, and directing the laser beam in a direction of propagation, and wherein the working surface is closer to the laser source than the focal point along the direction of propagation of the laser beam. 
     
     
         3 . The method of  claim 1 , wherein the focusing includes passing the laser beam through the transparent dielectric material. 
     
     
         4 . The method of  claim 1 , wherein the transparent dielectric material comprises glass. 
     
     
         5 . The method of  claim 1 , wherein the focal point is within 10 μm of an interface between the working surface and the liquid. 
     
     
         6 . The method of  claim 1 , wherein the laser beam induces non-linear absorption in the transparent dielectric material. 
     
     
         7 . The method of  claim 6 , wherein the laser beam forms a feature in the transparent dielectric material, the feature comprising a hole, groove, channel, slot, or recess. 
     
     
         8 . The method of  claim 7 , wherein forming the feature includes ablating the transparent dielectric material. 
     
     
         9 . The method of  claim 7 , wherein the feature extends through a thickness of the transparent dielectric material. 
     
     
         10 . The method of  claim 7 , wherein the feature has a cross-section with a linear dimension, the linear dimension having a variability attributable to RMS surface roughness of 1.0 μm or less. 
     
     
         11 . The method of  claim 10 , wherein the feature has an aspect ratio 4:1 or greater. 
     
     
         12 . The method of  claim 10 , wherein the cross-section is circular and the linear dimension is diameter. 
     
     
         13 . The method of  claim 7 , wherein forming the feature comprises forming a plurality of micromachined regions in the transparent dielectric material. 
     
     
         14 . The method of  claim 13 , wherein the plurality of micromachined regions are arranged in a helical pattern. 
     
     
         15 . The method of  claim 1 , wherein the fluorinated compound is selected from the group consisting of fluorinated alkanes, fluorinated alcohols, and fluorinated amines. 
     
     
         16 . The method of  claim 1 , wherein the concentration of the fluorine in the fluorinated compound is 30 wt % or greater. 
     
     
         17 . The method of  claim 1 , wherein the liquid has a boiling point 150° C. or greater. 
     
     
         18 . The method of  claim 1 , wherein the liquid has a surface tension 40 dynes/cm or less at 25° C. 
     
     
         19 . The method of  claim 1 , further comprising moving the focal point toward the working surface. 
     
     
         20 . The method of  claim 19 , wherein the focal point is moved across the interface of the working surface and the liquid. 
     
     
         21 . A transparent dielectric material comprising a hole, the hole having a circular cross-section with a diameter, the diameter having a variability attributable to RMS surface roughness of 0.5 μm or less. 
     
     
         22 . The transparent dielectric material of  claim 21 , wherein the hole has an aspect ratio 4:1 or greater. 
     
     
         23 . The transparent dielectric material of  claim 21 , further comprising an optical fiber, the optical fiber inserted in the hole. 
     
     
         24 . The transparent dielectric material of  claim 21 , wherein a surface of the transparent dielectric material adjacent to the hole comprises a chip, the chip having a longest linear dimension less than 5.0 μm.