Solar cell and method for manufacturing the same
View Patent ↗A solar cell is discussed. The solar cell includes a semiconductor substrate of a first conductive type, an emitter region of a second conductive type opposite the first conductive type, which is positioned at a front surface of the semiconductor substrate, a front passivation part positioned on a front surface of the emitter region, a front electrode part which passes through the front passivation part and is electrically connected to the emitter region, a back passivation part positioned on a back surface of the semiconductor substrate, and a back electrode part which passes through the back passivation part and is electrically connected to the semiconductor substrate. The front passivation part and the back passivation part each include a silicon oxide layer. One of the front passivation part and the back passivation part includes an aluminum oxide layer.
1. A method for manufacturing a solar cell, the method comprising:
respectively forming a front aluminum oxide (AlOx) layer and a back aluminum oxide (AlOx) layer on a front surface and a back surface of a semiconductor substrate simultaneously by an atomic layer deposition (ALD) method;
annealing the front and back aluminum oxide layers on the front surface and the back surface of the semiconductor substrate at a temperature of about 450° C. to 700° C. to form a front silicon oxide (SiOx) layer having a thickness of about 1 nm to 3 nm between the front aluminum oxide layer and the front surface of the semiconductor substrate and a back silicon oxide (SiOx) layer having a thickness of about 1 nm to 3 nm between the back aluminum oxide layer and the back surface of the semiconductor substrate; and
removing one of the front aluminum oxide layer and the back aluminum oxide layer depending on a conductive type of the semiconductor substrate after the step of annealing the front and back aluminum oxide layers, thereby leaving the front silicon oxide layer and the back silicon oxide layer regardless of the conductive type of the semiconductor substrate, and thereby leaving only one of the front aluminum oxide layer or the back aluminum oxide layer depending on the conductive type of the semiconductor substrate.
2. The method for manufacturing a solar cell of claim 1 , further comprising:
forming a hydrogenated silicon nitride (SiNx:H) layer on a front surface of the front aluminum oxide layer or a back surface of the back aluminum oxide layer.
3. The method for manufacturing a solar cell of claim 2 , wherein the hydrogenated silicon nitride (SiNx:H) layer is on the front aluminum oxide layer and is used as a mask during the removing of the back aluminum oxide layer.
4. The method for manufacturing a solar cell of claim 2 , wherein the hydrogenated silicon nitride (SiNx:H) layer is on the back aluminum oxide layer and is used as a mask during the removing of the front aluminum oxide layer.
5. The method for manufacturing a solar cell of claim 1 , further comprising:
forming an emitter region between the front surface of the semiconductor substrate and the front silicon oxide layer on the front surface of the semiconductor substrate.
6. The method for manufacturing a solar cell of claim 5 , further comprising:
forming a front electrode part, which is electrically connected to the emitter region, on the front surface of the semiconductor substrate.
7. The method for manufacturing a solar cell of claim 1 , further comprising:
forming a back surface field region between the back surface of the semiconductor substrate and the back silicon oxide layer on the back surface of the semiconductor substrate.
8. The method for manufacturing a solar cell of claim 7 , further comprising:
faulting a back electrode part, which is electrically connected to the back surface field region, on the back surface of the semiconductor substrate.
9. The method for manufacturing a solar cell of claim 1 , wherein the front aluminum oxide layer is used as a front surface field region.
10. The method for manufacturing a solar cell of claim 1 , wherein the step of removing is performed by a wet etching process or a cleaning process.
11. The method for manufacturing a solar cell of claim 10 , wherein the wet etching process is performed by a Hydrogen chloride (HCl) etchant.
12. The method for manufacturing a solar cell of claim 10 , wherein the cleaning process is performed by de-ionized water (DI).
13. The method for manufacturing a solar cell of claim 1 , wherein when the first conductive type of the semiconductor substrate is an n-type, the back aluminum oxide layer on the back surface of the semiconductor substrate is removed.
14. The method for manufacturing a solar cell of claim 1 , wherein when the first conductive type of the semiconductor substrate is a p-type, the front aluminum oxide layer on the front surface of the semiconductor substrate is removed.
15. The method for manufacturing a solar cell of claim 1 , wherein the thickness of the front silicon oxide layer is the same as the thickness of the back silicon oxide layer.