| CPC H01L 31/022441 (2013.01) [H01L 31/0236 (2013.01); H01L 31/02168 (2013.01); H01L 31/02363 (2013.01); H01L 31/02366 (2013.01); H01L 31/0682 (2013.01); H01L 31/18 (2013.01); H01L 31/1804 (2013.01); Y02E 10/547 (2013.01); Y02P 70/50 (2015.11)] | 13 Claims |
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1. A fabrication method of a back contact solar cell having a plurality of different conductive type semiconductor regions on a rear surface of a first conductive type semiconductor substrate, the method comprising:
forming a pyramid-shaped front texturing structure and a pyramid-shaped rear texturing structure at front and rear surfaces, respectively, of the substrate via etching by immersing the substrate in an etching solution;
forming thermal oxide layers both on the front and rear surfaces, respectively, of the substrate at the pyramid-shaped front and rear texturing structures using a rapid thermal oxidation scheme in a rapid thermal processing furnace or by a sputtering method using silicon oxide as a target material;
forming first patterns by locally removing a thermal oxide layer formed on the rear surface of the substrate from among the thermal oxide layers by irradiating a laser light to the thermal oxide layer formed on the rear surface at predetermined intervals, and the pyramid-shaped rear texturing structure is not present where the thermal oxide layer is partially removed;
forming first conductive type semiconductor regions on the rear surface of the substrate through the first patterns by thermal diffusion in a high-temperature furnace by flowing a first conductive type material into an inside of the high-temperature furnace to dope the first conductive type material at the first patterns;
forming, subsequent to the forming the first conductive type semiconductor regions, second patterns by locally removing the thermal oxide layer formed on the rear surface of the substrate by irradiating a laser light to the thermal oxide layer formed on the rear surface that remains at the predetermined intervals with the first patterns, and the pyramid-shaped rear texturing structure is not present where the thermal oxide layer is partially removed, and the pyramid-shaped rear texturing structure remains only between the first conductive type semiconductor regions and second conductive type semiconductor regions at the rear surface of the substrate;
forming the second conductive type semiconductor regions on the rear surface of the substrate through the second patterns by a dopant screen printing to print a second conductive type material to dope the second conductive type material at the second patterns so that the first conductive type semiconductor regions and the second conductive type semiconductor regions are respectively formed by different doping methods; and
forming first electrodes being in direct contact with the first conductive type semiconductor regions through the first patterns and second electrodes being in direct contact with the second conductive type semiconductor regions through the second patterns,
wherein a thermal oxide layer at the front surface acts as a front protection layer,
wherein, in the forming of the first conductive type semiconductor regions by the thermal diffusion, the thermal oxide layer at the rear surface acts as a mask for protecting portions corresponding to the second conductive type semiconductor regions at the rear surface,
wherein, after the forming of the second patterns, the thermal oxide layer at the rear surface remains between the first patterns and the second patterns and acts as a rear protection layer,
wherein the thermal oxide layer remaining on the rear surface is spaced apart so as not to overlap the first conductivity type regions and the second conductivity type regions in a vertical direction, and
wherein the first electrodes are formed so as to cover an entire surface of the first conductive type semiconductor regions and extend over an adjacent portion of the thermal oxide layer at the rear surface, and the second electrodes are formed so as to cover an entire surface of the second conductive type semiconductor regions and extend over an adjacent portion of the thermal oxide layer at the rear surface.
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