Interdigitated back contact solar cell and method for producing an interdigitated back contact solar cell

A method for producing an interdigitated back contact solar cell, the interdigitated back solar cell comprising:

• a monocrystalline, n-doped wafer (101),
• a first contact area (40) which is formed by a first stack on the surface of said monocrystalline wafer (101), said first stack comprising a thin silicon oxide layer (201) and a highly n-doped polycrystalline silicon layer (301), and
• a second contact area (20) which is formed by a second stack on the same surface of said monocrystalline wafer (101) as said first stack, said second stack comprising a thin silicon oxide layer (202) and a highly p-doped polycrystalline silicon layer (701),
• wherein a p-doped monocrystalline silicon region (801) is located in a gap (30) between said first contact area (40) and said second contact area (20), the p-dopant locally diffused into the highly p-doped polycrystalline silicon layer only where the second contact area (20) is created, thereby obtaining a local highly doped region, which is not etched in a subsequent alkaline etching step, thereby creating a gap region (30),
• said method comprising the steps of:
• creating a first contact area (40) which is formed by a first stack on the surface of a monocrystalline, n-doped wafer (101), said first stack comprising a thin silicon oxide layer (201) and a highly n-doped polycrystalline silicon layer (301),
• creating a second contact area (20) which is formed by a second stack on the same surface of said monocrystalline, n-doped wafer (101) as said first stack, said second stack comprising a thin silicon oxide layer (202) and a highly p-doped polycrystalline silicon layer (701),
• creating a gap (30) between the said first contact area and said second contact area,
• creating a p-doped monocrystalline silicon region (801) located in the gap (30) between said first contact area (40) and said second contact area (20), and
• after the first contact area (40) has been created, alkaline etching is performed in an area of the surface of the monocrystalline, n-doped wafer (101) outside of the first contact area (40) but comprising the area in which the second contact area (20) is to be created, so that the thickness of the monocrystalline, n-doped silicon wafer (101) is reduced in the area where the alkaline etching is performed.