Incident radiation induced subsurface damage for controlled crack propagation in material cleavage

Abstract

A cleaving system employs a shaper, a positioner, an internal preparation system, an external preparation system, a cleaver, and a cropper to cleave a workpiece into cleaved pieces. The shaper shapes a workpiece into a defined geometric shape. The positioner then positions the workpiece such that the internal preparation system can generate a separation layer at the cleaving plane. The internal preparation system focuses a laser beam internal to the workpiece at a focal point and scans the focal point across the cleaving plane to create the separation layer. The external preparation system scores the external surface of the workpiece at a location coincident with the separation layer. The cleaver cleaves the workpiece by propagating the crack on the external surface along the separation layer. The cropper shapes the cleaved piece into a geometric shape as needed.

1 . A method for cleaving a workpiece of a material, comprising:
 creating, using a laser generated by an internal preparation system, a separation layer within the workpiece having dissimilar material properties to the remaining material of the workpiece;   scoring, using an external preparation system, the workpiece to create a crack on an external surface of the workpiece, the crack configured to propagate from the external surface to the separation layer within the workpiece; and   cleaving, using a cleaver, the workpiece to create a cleaved piece by generating a stress within the workpiece that causes the crack to propagate from the external surface along the separation layer within the workpiece.   
     
     
         2 . The method of  claim 1 , further comprising:
 determining, using a controller, a position of a cleaving surface within the workpiece;   positioning, using a positioner, the workpiece such that the cleaving surface and the separation layer are coincident;   
     
     
         3 . The method of  claim 1 , wherein the separation layer created within the workpiece is a non-planar topological surface. 
     
     
         4 . The method of  claim 1 , wherein creating the separation layer within the workpiece further comprises:
 regulating, using the laser, thermal energy at the separation layer such that the thermal energy changes the material properties of the workpiece at the separation layer.   
     
     
         5 . The method of  claim 1 , wherein creating the separation layer further comprises:
 focusing the laser to a footprint internal to the workpiece, wherein a pulse of the laser locally changes the material properties of the workpiece at the footprint.   
     
     
         6 . The method of  claim 1 , wherein creating the separation layer further comprises:
 moving a focal point of the laser within the workpiece to create the separation layer, the separation layer formed as an aggregation of locally modified material at the focal point as it moves within the workpiece.   
     
     
         7 . The method of  claim 1 , wherein the crack on the external surface of the workpiece is not coincident with the separation layer. 
     
     
         8 . The method of  claim 1 , wherein the crack on the external surface of the workpiece is coincident with the separation layer at one or more points. 
     
     
         9 . The method of  claim 1 , wherein the generated stress is due to a force applied to the workpiece with a component normal to the separation layer at one or more points within the workpiece such that the crack propagates along the separation layer. 
     
     
         10 . The method of  claim 1 , further comprising:
 shaping, with a shaping system, the workpiece to a defined geometric shape such that the cleaved piece has a perimeter that is a cross-section of the defined geometric shape.   
     
     
         11 . The method of  claim 1 , further comprising:
 cropping, using a cropper, the cleaved piece into a particular geometry.   
     
     
         12 . The method of  claim 1 , wherein scoring the workpiece to create the crack on the external surface of the workpiece further comprises:
 determining one or more of a depth, a width, a crack tip sharpness, or a shape of the crack;   wherein the external preparation system scores the workpiece such that the crack has the determined depth, width, crack tip sharpness, or shape; and   wherein propagation of the crack from the external surface along the separation layer within the workpiece is based on the depth, width, crack tip sharpness, or shape.   
     
     
         13 . The method of  claim 1 , further comprising:
 creating, using the laser, another separation layer within the workpiece having dissimilar material properties.   
     
     
         14 . The method of  claim 13 , further comprising:
 cleaving, using the cleaver, the workpiece along the other separation layer to create an additional cleaved piece.   
     
     
         15 . The method of  claim 1 , further comprising:
 determining a location of the separation layer in the workpiece based on a proximity of at least one additional separation layer within the workpiece, and   wherein the internal preparation system creates the separation layer at the determined location.   
     
     
         16 . The method of  claim 1 , further comprising:
 scoring, using the external preparation system, the workpiece to create an additional crack on the external surface of the workpiece, the additional crack configured to facilitate fracturing in creating the cleaved piece.   
     
     
         17 . The method of  claim 16 , wherein the crack on the external surface of the workpiece is coincident with the separation layer at one or more points, and the additional crack on the external surface of the workpiece is not coincident with the separation layer. 
     
     
         18 . A system for cleaving a workpiece of a material, comprising:
 an internal preparation system configured to generate a laser beam for creating a separation layer within the workpiece, the separation layer having dissimilar material properties to the remaining material of the workpiece;   an external preparation system configured to create a crack on an external surface of the workpiece, wherein the crack is configured to propagate from the external surface to the separation layer within the workpiece; and   a cleaver configured to create a cleaved piece of the workpiece by generating a stress within the workpiece that causes the crack to propagate from the external surface along the separation layer within the workpiece.   
     
     
         19 . The system of  claim 18 , further comprising:
 a controller configured to determine a position of a cleaving surface within the workpiece; and   a positioner configured to position the workpiece such that the cleaving surface is coincident with the separation layer.   
     
     
         20 . The system of  claim 18 , wherein the separation layer created within the workpiece is a non-planar topological surface. 
     
     
         21 . The system of  claim 18 , wherein the internal preparation system is further configured to regulate, using the laser, the thermal energy at the separation layer such that the thermal energy changes the material properties of the workpiece at the separation layer. 
     
     
         22 . The system of  claim 18 , wherein the internal preparation system is further configured to focus the laser to a footprint internal to the workpiece, and wherein a pulse of the laser locally changes the material properties of the workpiece at the footprint. 
     
     
         23 . The system of  claim 18 , wherein the internal preparation system is further configured to move a focal point of the laser within the workpiece to create the separation layer, the separation layer formed as an aggregation of locally modified material at the focal point as it moves within the workpiece. 
     
     
         24 . The system of  claim 18 , wherein the crack on the external surface of the workpiece is not coincident with the separation layer. 
     
     
         25 . The system of  claim 18 , wherein the crack on the external surface of the workpiece is coincident with the separation layer at one or more points. 
     
     
         26 . The system of  claim 18 , wherein the generated stress is due to a force applied to the workpiece with a component normal to the separation layer at one or more points within the workpiece such that the crack propagates along the separation layer. 
     
     
         27 . The system of  claim 18 , further comprising:
 a shaping system configured to shape the workpiece to a defined geometric shape such that the cleaved piece has a perimeter that is a cross-section of the defined geometric shape.   
     
     
         28 . The system of  claim 18 , further comprising:
 a cropper configured to crop the cleaved piece into a particular geometry.   
     
     
         29 . The system of  claim 18 , further comprising:
 a controller configured to determine one or more of a depth, a width, a crack tip sharpness, or a shape of the crack;   wherein the external preparation system is further configured to score the workpiece such that the crack has the determined depth, width, crack tip sharpness, or shape; and   wherein propagation of the crack from the external surface along the separation layer within the workpiece is based on the depth, width, crack tip sharpness, or shape.   
     
     
         30 . The system of  claim 18 , wherein the internal preparation system is further configured to create, using the laser, another separation layer within the workpiece having dissimilar material properties. 
     
     
         31 . The system of  claim 30 , wherein the cleaver is further configured to cleave the workpiece along the other separation layer to create an additional cleaved piece. 
     
     
         32 . The system of  claim 18 , further comprising:
 a controller configured to determine a location of the separation layer in the workpiece based on a proximity of at least one additional separation layer within the workpiece, and   wherein the internal preparation system is configured to create the separation layer at the determined location.   
     
     
         33 . The system of  claim 18 , wherein the external preparation system is further configured to score the workpiece to create an additional crack on the external surface of the workpiece, the additional crack configured to facilitate fracturing in creating the cleaved piece. 
     
     
         34 . The system of  claim 33 , wherein the crack on the external surface of the workpiece is coincident with the separation layer at one or more points, and the additional crack on the external surface of the workpiece is not coincident with the separation layer.