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 . An apparatus comprising a cleaved single crystal sapphire layer having a thickness of between about 5 μm to about 100 μm. 
     
     
         2 . An apparatus as in  claim 1  further comprising a laminated structure including an optical blank and an index matching material positioned between the cleaved single crystal sapphire layer and the optical blank. 
     
     
         3 . An apparatus as in  claim 2  wherein the cleaved single crystal sapphire layer is free standing. 
     
     
         4 . An apparatus as in  claim 3  wherein the optical blank and index matching material comprise a support. 
     
     
         5 . An apparatus as in  claim 2  wherein:
 the index matching material comprises an index-matching fluid; and 
 the optical blank comprises quartz. 
 
     
     
         6 . An apparatus as in  claim 5  wherein an index of refraction of the index-matching fluid results in an internal reflection at the quartz/sapphire interface of less than 1%. 
     
     
         7 . An apparatus as in  claim 5  wherein:
 an index of refraction of the index-matching fluid results in an internal reflection at the quartz/sapphire interface of greater than 1%; and 
 the index matching material further comprises a dielectric stack matching material. 
 
     
     
         8 . An apparatus as in  claim 2  wherein a surface of the cleaved single crystal sapphire layer is defined by a fracture plane resulting from hydrogen implantation. 
     
     
         9 . An apparatus as in  claim 8  wherein a Total Thickness Variation (TTV) of the cleaved single crystal sapphire layer is +/−0.02 μm. 
     
     
         10 . An apparatus as in  claim 9  wherein a roughness of the cleaved single crystal sapphire layer is about 6 nm Ra. 
     
     
         11 . An apparatus as in  claim 9  wherein the fracture plane results from hydrogen implantation by a linear accelerator at an energy of 1.75 MeV or greater. 
     
     
         12 . An apparatus as in  claim 9  wherein the laminated structure has a thickness of between 400-600 μm. 
     
     
         13 . An apparatus as in  claim 2  wherein the cleaved single crystal sapphire layer reproduces a pseudo-square shape of a bulk core. 
     
     
         14 . An apparatus as in  claim 2  further comprising:
 a second cleaved single crystal sapphire layer positioned on an opposite side of the optical blank from the cleaved single crystal sapphire layer; and 
 a second index matching material positioned between the optical blank and the second cleaved single crystal sapphire layer. 
 
     
     
         15 . An apparatus as in  claim 1  wherein the cleaved single crystal sapphire layer is characterized by a miscut angle from a major crystallographic axis. 
     
     
         16 . An apparatus as in  claim 15  wherein the cleaved single crystal sapphire layer comprises c-cut oriented material. 
     
     
         17 . An apparatus as in  claim 1  wherein the cleaved single crystal sapphire layer has other than a planar shape. 
     
     
         18 . An apparatus as in  claim 17  wherein the cleaved single crystal sapphire layer is curved to match a lens profile. 
     
     
         19 . An apparatus as in  claim 1  wherein the apparatus comprises a part of a cover for a display screen. 
     
     
         20 . An apparatus as in  claim 1  wherein the apparatus comprises an optical surface of a biometric recognition device.