Apparatus and method of cleaving thin layer from bulk material

Abstract

Embodiments relate to use of a particle accelerator beam to form thin layers of material from a bulk substrate. In particular embodiments, a bulk substrate (e.g. donor substrate) having a top surface is exposed to a beam of accelerated particles. In certain embodiments, this bulk substrate may comprise a core of crystalline sapphire (Al 2 O 3 ) material. Then, a thin layer of the material is separated from the bulk substrate by performing a controlled cleaving process along a cleave region formed by particles implanted from the beam. Embodiments may find particular use as hard, scratch-resistant covers for personal electric device displays, or as optical surfaces for fingerprint, eye, or other biometric scanning.

What is claimed is: 
     
         1 . A method comprising:
 implanting a plurality of protons into single crystal sapphire material at a temperature of between 650-850° C. to form a cleave region; and   performing a controlled cleaving process to separate a cleaved single crystal sapphire layer having a thickness of between 5-100 μm from the single crystal material along the cleave region,   wherein the controlled cleaving process comprises applying additional energy in a spatially varying manner to cause controlled cleaving of the single crystal sapphire material propagated in a direction along the cleave region, and   wherein the cleaved single crystal sapphire layer has a Total Thickness Variation (TTV) of +/−0.02 μm and a roughness of about 6 nm Ra.   
     
     
         2 . A method as in  claim 1  wherein the plurality of protons are implanted from a linear accelerator, and the cleaved single crystal sapphire layer is free standing. 
     
     
         3 . A method as in  claim 1  further comprising:
 providing the cleaved single crystal sapphire layer; and 
 providing an optical blank; and 
 providing an index matching material positioned between the cleaved single crystal sapphire layer and the optical blank to form an optical laminate. 
 
     
     
         4 . A method as in  claim 3  wherein:
 the plurality of protons are implanted from a linear accelerator; 
 the cleaved single crystal sapphire layer is free standing; and 
 the optical blank and index matching material comprise a support of the cleaved single crystal sapphire layer. 
 
     
     
         5 . A method as in  claim 3  wherein the optical blank comprises quartz. 
     
     
         6 . A method as in  claim 5  wherein the index matching material comprises an index-matching fluid. 
     
     
         7 . A method as in  claim 3  further comprising disposing a second index matching material on an opposite side of the optical blank from the cleaved single crystal sapphire layer, between the optical blank and a second cleaved single crystal sapphire layer. 
     
     
         8 . A method as in  claim 1  wherein the single crystal sapphire material comprises a multi-layered substrate. 
     
     
         9 . A method as in  claim 1  further comprising:
 detecting a temperature during the accelerating; and 
 controlling an implant heat flux to maintain the temperature between 650-850° C. 
 
     
     
         10 . A method as in  claim 9  further comprising applying a coating to the single crystal sapphire material, wherein the detecting comprises detecting a temperature of the coating. 
     
     
         11 . A method as in  claim 10  further comprising matching an implant heat flux to a radiation cooling flux of the coating. 
     
     
         12 . A method as in  claim 10  wherein the additional energy comprising luminance absorbed by the coating. 
     
     
         13 . A method as in  claim 10  further comprising heating the coating to 500° C. or greater prior to the implanting. 
     
     
         14 . A method as in  claim 1  wherein the plurality of protons are implanted by a scanned beam. 
     
     
         15 . A method as in  claim 14  wherein :
 the scanned beam is configured to implant protons into a plurality of single crystal sapphire materials comprising rounded cores; and 
 the scanned beam is patterned to avoid gaps between the rounded cores. 
 
     
     
         16 . A method as in  claim 14  wherein:
 the temperature of implantation is 800° C. or greater; and 
 the scanned beam contributes to initiating and/or propagating the controlled cleaving process. 
 
     
     
         17 . A method as in  claim 14  wherein the scanned beam has a dwell time of  80  us or longer. 
     
     
         18 . A method as in  claim 1  wherein the additional energy comprises an electron beam. 
     
     
         19 . A method as in  claim 1  wherein the controlled cleaving process further comprises cooling the single crystal sapphire material. 
     
     
         20 . A method as in  claim 19  wherein the cooling creates a thermal shock. 
     
     
         21 . A method as in  claim 1  wherein the cleaved single crystal sapphire layer is characterized by a miscut angle from a major crystallographic axis. 
     
     
         22 . A method as in  claim 1  wherein the cleaved single crystal sapphire layer comprises c-cut oriented material. 
     
     
         23 . A method as in  claim 1  wherein the cleaved single crystal sapphire layer comprises a-cut oriented material. 
     
     
         24 . A method as in  claim 1  wherein the cleaved single crystal sapphire layer comprises m-cut oriented material. 
     
     
         25 . A method as in  claim 1  wherein the cleaved single crystal sapphire layer comprises r-cut oriented material.