Solar cell and method for manufacturing the same

Abstract

A method for manufacturing a solar cell, the method comprising: forming an emitter region that forms a p-n junction with a semiconductor substrate of a first conductive type; forming a passivation layer on the semiconductor substrate; forming a dopant layer containing impurities of the first conductive type on the passivation layer; and locally forming a back surface field region at the semiconductor substrate by irradiating laser beams onto the semiconductor substrate to diffuse the impurities of the first conductive type into the semiconductor substrate.

What is claimed is: 
     
         1 . A method for manufacturing a solar cell, the method comprising:
 forming an emitter region that forms a p-n junction with a semiconductor substrate of a first conductive type;   forming a passivation layer on the semiconductor substrate;   forming a dopant layer containing impurities of the first conductive type on the passivation layer; and   locally forming a back surface field region at the semiconductor substrate by irradiating laser beams onto the semiconductor substrate to diffuse the impurities of the first conductive type into the semiconductor substrate.   
     
     
         2 . The method of  claim 1 , wherein the forming of the back surface field region forms the back surface field region by irradiating the laser beams on the dopant layer to diffuse the impurities of the first conductive type of the dopant layer into the semiconductor substrate. 
     
     
         3 . The method of  claim 1 , further comprising forming an anti-reflection layer on the emitter region. 
     
     
         4 . The method of  claim 3 , further comprising forming a first electrode and a second electrode, which comprises:
 providing a first electrode paste on the anti-reflection layer;   providing a second electrode paste on the dopant layer; and   heating the semiconductor substrate with the first electrode paste and the second electrode paste.   
     
     
         5 . The method of  claim 1 , further comprising:
 providing a second electrode paste on the dopant layer; and   the locally forming of the back surface field region includes irradiating the laser beams on the second electrode paste to diffuse the impurities of the first conductive type of the dopant layer into the semiconductor substrate.   
     
     
         6 . The method of  claim 5 , further comprising forming an anti-reflection layer on the emitter region. 
     
     
         7 . The method of  claim 6 , further comprising:
 providing a first electrode paste on the anti-reflection layer; and   heating the semiconductor substrate with the first electrode paste and the second electrode paste.   
     
     
         8 . The method of  claim 1 , wherein the back surface field region has an impurity concentration of the first conductive type that is higher than an impurity concentration of the first conductive type of the semiconductor substrate. 
     
     
         9 . The method of  claim 1 , wherein the forming of the dopant layer forms the dopant layer using one of a spin on doping method, a direct printing method, a screen printing method, and a spray doping method. 
     
     
         10 . The method of  claim 1 , wherein the laser beams have a pulse width of about 10 femto seconds to about 50 nano seconds. 
     
     
         11 . The method of  claim 1 , further comprising forming a plurality of through holes in the passivation layer. 
     
     
         12 . The method of  claim 11 , wherein the passivation layer is a multi-layer structure. 
     
     
         13 . The method of  claim 11 , the passivation layer is entirely and directly formed on a back surface of the semiconductor substrate, except for the back surface field region exposed by the plurality of through holes. 
     
     
         14 . The method of  claim 11 , wherein the plurality of through holes is filled with a mixture comprising a material of the dopant layer and a material of the passivation layer. 
     
     
         15 . The method of  claim 4 , wherein outer surface of the dopant layer contacted with the second electrode has a plurality of depressed portions. 
     
     
         16 . A method for manufacturing a solar cell, the method comprising:
 forming an emitter region that forms a p-n junction with a semiconductor substrate of a first conductive type;   forming an anti-reflection layer on the emitter region;   forming a passivation layer on the semiconductor substrate;   forming a dopant layer containing impurities of the first conductive type on the passivation layer;   providing a first electrode paste on the anti-reflection layer;   providing a second electrode paste on the dopant layer;   locally forming a back surface field region at the semiconductor substrate by irradiating laser beams onto the second electrode paste to diffuse the impurities of the first conductive type into the semiconductor substrate;   heating the semiconductor substrate with the first electrode paste and the second electrode paste to form a first electrode and a second electrode; and   locally forming a back surface field region at the semiconductor substrate by irradiating laser beams onto the semiconductor substrate to diffuse the impurities of the first conductive type into the semiconductor substrate.   
     
     
         17 . The method of  claim 16 , further comprising forming a plurality of through holes in the passivation layer. 
     
     
         18 . The method of  claim 17 , wherein the plurality of through holes is filled with a mixture comprising a material of the dopant layer and a material of the second electrode. 
     
     
         19 . The method of  claim 18 , wherein the mixture is a mixture (B+Al) of boron (B) and aluminum (Al). 
     
     
         20 . The method of  claim 16 , wherein outer surface of the dopant layer contacted with the second electrode has a plurality of first depressed portions, and
 wherein inner surface of the second electrode contacted with the dopant layer has a plurality of second depressed portions and outer surface of the second electrode is flat.