Thermally grown silicon dioxide is commonly used in high-efficiency monocrystalline silicon solar cell designs as a diffusion mask, electroless plating mask, passivation layer and rudimentary anti-reflection coating. These high efficiency device designs also utilize upright random textured up-pyramids etched by alkalinous solution to minimize front surface reflection. The silicon solar cells passivated with thermal SiO2/plasma SiN stacks have the evident character: the dark reverse current-voltage curve presents "soft breakdown", and the shunt resistance is lower than that of silicon solar cells passivated with the plasma SiN. The study shows that the cause of monocrystalline silicon solar cell performance degradation is the dislocation induced by the thermal growth of silicon dioxide on textured wafers. The performance of thermal SiO2/plasma SiN stack passivated silicon solar cells has evident improvement when a 2-min isotropic etching was applied after surface texturing to round off the pyramids.