Solar cell fabrication using laser patterning of ion-implanted etch-resistant layers and the resulting solar cells

Abstract

Solar cell fabrication using laser patterning of ion-implanted etch-resistant layers, and the resulting solar cells, are described. In an example, a back contact solar cell includes an N-type single crystalline silicon substrate having a light-receiving surface and a back surface. Alternating continuous N-type emitter regions and segmented P-type emitter regions are disposed on the back surface of the N-type single crystalline silicon substrate, with gaps between segments of the segmented P-type emitter regions. Trenches are included in the N-type single crystalline silicon substrate between the alternating continuous N-type emitter regions and segmented P-type emitter regions and in locations of the gaps between segments of the segmented P-type emitter regions. An approximately Gaussian distribution of P-type dopants is included in the N-type single crystalline silicon substrate below the segmented P-type emitter regions. A maximum concentration of the approximately Gaussian distribution of P-type dopants is approximately in the center of each of the segmented P-type emitter regions between first and second sides of each of the segmented P-type emitter regions. Substantially vertical P/N junctions are included in the N-type single crystalline silicon substrate at the trenches formed in locations of the gaps between segments of the segmented P-type emitter regions.

1 .- 18 . (canceled) 
     
     
         19 . A solar cell, comprising:
 a substrate having a light-receiving surface and a back surface;   continuous emitter regions of a first conductivity type and rectangularly segmented emitter regions of a second conductivity type disposed on the back surface of the substrate, the continuous emitter regions separate from the rectangularly segmented emitter regions, with gaps between segments of the rectangularly segmented emitter regions;   an isolation material region located at the gaps between segments of the rectangularly segmented emitter regions; and   an oxide layer coextensive with each continuous emitter regions and each segment of the rectangularly segmented emitter regions, each oxide layer between the back surface of substrate and the corresponding continuous emitter region or corresponding segment of the rectangularly segmented emitter regions.   
     
     
         20 . The solar cell of  claim 19 , wherein the isolation material region comprises silicon nitride. 
     
     
         21 . The solar cell of  claim 19 , wherein the continuous emitter regions comprise doped polycrystalline silicon emitter regions. 
     
     
         22 . The solar cell of  claim 19 , wherein the rectangularly segmented emitter regions comprise doped polycrystalline silicon emitter regions. 
     
     
         23 . The solar cell of  claim 19 , wherein the continuous emitter regions comprise phosphorous. 
     
     
         24 . The solar cell of  claim 19 , wherein the continuous emitter regions comprise arsenic. 
     
     
         25 . The solar cell of  claim 19 , wherein the rectangularly segmented emitter regions comprise boron. 
     
     
         26 . The solar cell of  claim 19 , wherein the gaps between segments of the rectangular segmented emitter regions have approximately Gaussian distribution of the second conductivity type in the substrate below each of the rectangularly segmented emitter regions, wherein a maximum concentration of the approximately Gaussian distribution of second conductivity is approximately in the center of each of the rectangularly segmented emitter regions between first and second sides of each of the rectangularly segmented emitter regions. 
     
     
         27 . A solar cell, comprising:
 a substrate having a light-receiving surface and a back surface;   continuous emitter regions of a first conductivity type and rectangularly segmented emitter regions of a second conductivity type disposed on the back surface of the substrate, the continuous emitter regions separate from the rectangularly segmented emitter regions, with gaps between segments of the rectangularly segmented emitter regions;   a continuity portions located at the gaps between segments of the rectangularly segmented emitter regions, wherein the continuity portions electrically connect the rectangularly segmented emitter regions; and   an oxide layer coextensive with each continuous emitter regions and each segment of the rectangularly segmented emitter regions, each oxide layer between the back surface of substrate and the corresponding continuous emitter region or corresponding segment of the rectangularly segmented emitter regions.   
     
     
         28 . The solar cell of  claim 27 , further comprising:
 an isolation material region located at the gaps between segments of the rectangularly segmented emitter regions.   
     
     
         29 . The solar cell of  claim 28 , wherein the isolation material region comprises silicon nitride. 
     
     
         30 . The solar cell of  claim 27 , wherein the continuous emitter regions comprise doped polycrystalline silicon emitter regions. 
     
     
         31 . The solar cell of  claim 27 , wherein the rectangularly segmented emitter regions comprise doped polycrystalline silicon emitter regions. 
     
     
         32 . The solar cell of  claim 27 , wherein the continuous emitter regions comprise phosphorous. 
     
     
         33 . The solar cell of  claim 27 , wherein the gaps between segments of the rectangularly segmented emitter regions have approximately Gaussian distribution of a second conductivity type in the substrate below each of the rectangularly segmented emitter regions, wherein a maximum concentration of the approximately Gaussian distribution of second conductivity is approximately in the center of each of the rectangularly segmented emitter regions between first and second sides of each of the rectangularly segmented emitter regions. 
     
     
         34 . A method of fabricating an emitter region of a solar cell, the method comprising:
 forming a semiconductor layer above a semiconductor substrate of a first conductivity type;   implanting dopant impurity atoms of a second conductivity type in the semiconductor layer to form an implanted region of the semiconductor layer and resulting in a non-implanted region of the semiconductor layer;   laser scribing at least an uppermost portion of the implanted region of the semiconductor layer to form scribe lines in the implanted region of the semiconductor layer;   removing the non-implanted region of the semiconductor layer and remaining portions of the semiconductor layer in the scribe lines using a selective etch process preserving remaining non-scribed portions of the implanted region of the semiconductor layer; and   annealing the semiconductor substrate to form an emitter region of the second conductivity type from the remaining non-scribed portions of the implanted region of the semiconductor layer and to form a region of dopant impurity atoms of the second conductivity type in the semiconductor substrate below the emitter region.   
     
     
         35 . The method of  claim 34 , wherein annealing the semiconductor substrate comprises forming an approximately Gaussian distribution of dopant impurity atoms of the second conductivity type in the semiconductor substrate below the implanted region of the semiconductor layer, wherein a maximum concentration of the approximately Gaussian distribution of dopant impurity atoms of the second conductivity type is approximately in the center of the implanted region of the semiconductor layer. 
     
     
         36 . The method of  claim 35 , wherein annealing the semiconductor substrate forms substantially vertical P/N junctions in the semiconductor in locations of the scribe lines. 
     
     
         37 . The method of  claim 34 , wherein removing comprises forming trenches in the semiconductor substrate in locations below the non-implanted region of the semiconductor layer and in locations below the scribe lines. 
     
     
         38 . The method of  claim 37 , wherein forming the trenches in the semiconductor substrate comprises using a hydroxide-based wet etchant.