Liquid phase growth method of silicon crystal, method of producing solar, cell, and liquid phase growth apparatus

Abstract

Provided are a liquid phase growth method of silicon crystal comprising a step of injecting a source gas containing at least silicon atoms into a solvent to decompose the source gas and, simultaneously therewith, dissolving the silicon atoms into the solvent, thereby supplying the silicon atoms into the solvent, and a step of dipping or contacting a substrate into or with the solvent, thereby growing a silicon crystal on the substrate; and a method of producing a solar cell utilizing the aforementioned method. Also provided is a liquid phase growth apparatus of a silicon crystal comprising means for holding a solvent in which silicon atoms are dissolved, and means for dipping or contacting a substrate into or with the solvent, the apparatus further comprising means for injecting a source gas containing at least silicon atoms into the solvent. These provide a liquid phase growth method of a silicon crystal and a production method of a solar cell each having high volume productivity and permitting continuous growth.

What is claimed is:  
     
         1 . A liquid phase growth method of a silicon crystal comprising a step of injecting a source gas comprising at least silicon atoms into a solvent to decompose the source gas and, simultaneously therewith, dissolving the silicon atoms into the solvent, thereby supplying the silicon atoms into the solvent, and a step of dipping or contacting a substrate into or with the solvent, thereby growing a silicon crystal on the substrate.  
     
     
         2 . The method according to  claim 1 , comprising a step of agitating the solvent and the silicon atoms by at least one of the source gas, a gas evolved by the decomposition of the source gas, and a gas injected into the solvent together with the source gas.  
     
     
         3 . The method according to  claim 1 , comprising a step of agitating the solvent and the silicon atoms by use of a mechanical means.  
     
     
         4 . The method according to  claim 1 , wherein the solvent is a solvent comprised of a metal.  
     
     
         5 . The method according to  claim 4 , wherein the metal is at least one selected from In, Sn, Bi, Ga, and Sb.  
     
     
         6 . The method according to  claim 1 , wherein the source gas comprises SiH 4 .  
     
     
         7 . The method according to  claim 1 , wherein the source gas comprises Si n H 2n+2  (n is an integer of 2 or more).  
     
     
         8 . The method according to  claim 1 , wherein the source gas comprises of a silane halide.  
     
     
         9 . The method according to  claim 1 , wherein the source gas contains a dopant.  
     
     
         10 . A method of producing a solar cell comprising at least a step of forming a silicon layer by liquid phase growth, the method comprising a step of injecting a source gas comprising at least silicon atoms into a solvent to decompose the source gas and, simultaneously therewith, dissolving the silicon atoms into the solvent, thereby supplying the silicon atoms into the solvent, and a step of dipping or contacting a substrate into or with the solvent, thereby growing a silicon crystal on the substrate to form the silicon layer.  
     
     
         11 . The method according to  claim 10 , comprising a step of agitating the solvent and the silicon atoms by at least one of the source gas, a gas evolved by the decomposition of the source gas, and a gas injected into the solvent together with the source gas.  
     
     
         12 . The method according to  claim 10 , comprising a step of agitating the solvent and the silicon atoms by use of a mechanical means.  
     
     
         13 . The method according to  claim 10 , wherein the solvent is a solvent comprised of a metal.  
     
     
         14 . The method according to  claim 13 , wherein the metal is at least one selected from In, Sn, Bi, Ga, and Sb.  
     
     
         15 . The method according to  claim 10 , wherein the source gas comprises SiH 4 .  
     
     
         16 . The method according to  claim 10 , wherein the source gas comprises Si n H 2n+2  (n is an integer of 2 or more).  
     
     
         17 . The method according to  claim 10 , wherein the source gas comprises a silane halide.  
     
     
         18 . The method according to  claim 10 , wherein the source gas contains a dopant.  
     
     
         19 . The method according to  claim 10 , further comprising a step of forming an n-type layer, after the step of forming the silicon layer by liquid phase growth.  
     
     
         20 . The method according to  claim 19 , wherein the n-type layer is formed by diffusing a dopant into a part of the silicon layer.  
     
     
         21 . A liquid phase growth apparatus of a silicon crystal comprising means for holding a solvent in which silicon atoms are dissolved, and means for dipping or contacting a substrate into or with the solvent, the apparatus further comprising means for injecting a source gas comprising at least silicon atoms into the solvent.  
     
     
         22 . A liquid phase growth apparatus of a silicon crystal comprising a solvent reservoir for holding a solvent in which silicon atoms are dissolved, a source gas inlet pipe having an opening portion in the solvent held in the solvent reservoir, a wafer cassette for holding a substrate, the wafer cassette being arranged to be freely taken into or out of the solvent held in the solvent reservoir, and a heater.  
     
     
         23 . The apparatus according to  claim 22 , further comprising a mechanical agitating means arranged to be freely taken into or out of the solvent.  
     
     
         24 . A liquid phase growth apparatus of a silicon crystal comprising a solvent reservoir and a growth vessel each for holding a solvent in which silicon atoms are dissolved, a pipe for circulating the solvent between the solvent reservoir and the growth vessel, a source gas inlet pipe having an opening portion in the solvent held in the solvent reservoir, a wafer cassette for holding a substrate, the wafer cassette being arranged to be freely taken into or out of the solvent held in the growth vessel, and a heater.  
     
     
         25 . The apparatus according to  claim 24 , further comprising means for making a difference between the temperature of the solvent in the solvent reservoir and the temperature of the solvent in the growth vessel.  
     
     
         26 . The apparatus according to  claim 25 , wherein the means for making the difference between the temperature of the solvent in the solvent reservoir and the temperature of the solvent in the growth vessel comprises a heater block surrounding the solvent reservoir.  
     
     
         27 . The apparatus according to  claim 24 , wherein at least a part of the pipe functions as a heat exchanger.  
     
     
         28 . A liquid phase growth apparatus of a silicon crystal comprising a solvent reservoir for holding a solvent in which silicon atoms are dissolved, a pipe both ends of which are connected to the solvent reservoir and which has an aperture portion except for the both ends, the pipe being provided for circulating the solvent, a source gas inlet pipe having an opening portion in the solvent held in the solvent reservoir, a holding member for holding a substrate so that the substrate is in contact with the solvent at the aperture portion, and a heater.  
     
     
         29 . The apparatus according to  claim 28 , further comprising means for making a difference between the temperature of the solvent in the solvent reservoir and the temperature of the solvent in the vicinity of the aperture portion.  
     
     
         30 . The apparatus according to  claim 29 , wherein the means for making the difference between the temperature of the solvent in the solvent reservoir and the temperature of the solvent in the vicinity of the aperture portion comprises a heater block surrounding the solvent reservoir.  
     
     
         31 . The apparatus according to  claim 28 , wherein at least a part of the pipe functions as a heat exchanger.