Patent ID: 8779280
Filing Date: 2014-07-15
Classification: H01L,Y02E,Y02P

Abstract:
1. A solar cell, comprising: a semiconductor substrate including a front surface and a back surface opposite the front surface, a first doped region of a first conductive type formed inside the back surface of the semiconductor substrate of the first conductive type; a second doped region formed inside the back surface of the semiconductor substrate at a location adjacent to the first doped region, the second doped region having a second conductive type opposite the first conductive type; a passivation layer formed on the back surface of the semiconductor substrate and configured to expose a portion of back surfaces of each of the first and second doped regions; a first electrode formed on the exposed portion of the first doped region, the first electrode including a metal seed layer having a front surface directly contacting the first doped region; and a second electrode formed on the exposed portion of the second doped region, the second electrode including a metal seed layer having a front surface directly contacting the second doped region, wherein the back surface of the semiconductor substrate is substantially flat, wherein the first doped region and the second doped region are linearly disposed inside the back surface of the substrate, wherein each of the first and second electrodes further includes at least one conductive layer positioned on the metal seed layer of each of the first and second electrodes, wherein the at least one conductive layer of each of the first and second electrodes includes a copper layer and a tin layer sequentially positioned on the metal seed layer of each of the first and second electrodes, wherein the tin layer entirely wraps an exposed surface of the copper layer, the exposed surface including a bottom surface and a side surface, wherein the tin layer comprises a bottom surface positioned on the bottom surface of the copper layer and a side surface positioned on the side surface of the copper layer, and wherein the side surface of the tin layer lies on an outermost end of the metal seed layer.