Method for manufacturing solar cell and solar cell manufactured by the same method
Disclosed are a method for manufacturing a solar cell by processing a surface of a silicon substrate for a solar cell, a solar cell manufactured by the method, and a substrate processing system for performing the method. The method for manufacturing a solar cell comprises protrusion forming step including wet-etching process and for forming a plurality of minute protrusions on a light receiving surface of a crystalline silicon substrate, and planarization step of planarizing the bottom surface, the opposite surface to the light receiving surface of the substrate during or after the protrusion forming step.
1. A method for manufacturing a solar cell, the method comprising:
protrusion forming step including wet-etching process, for forming a plurality of minute protrusions on a light receiving surface of a crystalline silicon substrate;
wherein the protrusion forming step comprises:
first protrusion forming step of forming a plurality of first protrusions on both of the light receiving surface and the bottom surface of the crystalline silicon substrate by etching the crystalline silicon substrate using acid aqueous solution; and
second protrusion forming step of forming a plurality of second protrusions smaller than the first protrusions, by dry-etching external surfaces of the light receiving surface having the first protrusions thereon through the first protrusion forming step, the light receiving surface where anti-reflection film is to be formed, and
planarization step of planarizing a bottom surface, which is opposite to the light receiving surface of the crystalline silicon substrate, to remove the plurality of the first protrusions formed in the first protrusion forming step, after the first protrusion forming step and before the second protrusion forming step.
2. The method of claim 1 , wherein the protrusion forming step comprises:
surface damage removing step of removing surface damages of surfaces of the crystalline silicon substrate by wet-etching process; and
minute protrusion forming step of forming minute protrusions by dry-etching the light receiving surface of the crystalline silicon substrate.
3. The method of claim 1 , wherein the planarization step is executed by wet-etching process.
4. The method of claim 1 , wherein the planarization step is executed by dry-etching process by making etching gas into plasma state.
5. The method of claim 4 , wherein the etching gas includes at least one of chlorine (Cl), fluorine, bromine (Br) and oxygen (O 2 ).
6. The method of claim 1 , wherein the planarization step is executed by covering a tray loaded with a plurality of crystalline silicon substrates, with a cover member formed with a plurality of openings.
7. The method of claim 6 , wherein the cover member is formed such that a space formed between the crystalline silicon substrate and the openings is open toward side surfaces of the cover member.
8. The method of claim 1 , further comprising a substrate inverting step of inverting the light receiving surface and the bottom surface of the crystalline silicon substrate before or after the planarization step.
9. The method of claim 1 , further comprising semiconductor layer forming step of forming p-n junction structure before the protrusion forming step, or after the planarization step.