In the fabrication process of interdigitated back contact (IBC) solar cell，one is using SiO

2

as a masking layer after boron diffusion and then diffusing phosphorus is used to form local back surface field (LBSF). Under the protection of SiO

2

the p-type emitter would stay unchanged and the area without SiO

2

will become n

+

LBSF. A gap covered with SiO

2

separates the emitter and LBSF. Thickness of thermal oxidation SiO

2

in different temperatures

from 0 nm to 124 nm

is investigated. Sheet resistance

minority carrier lifetime and diffusion profile by ECV before and after phosphorus diffusion are measured to see the effect of different silicon dioxide masking layers. With all these factors taken into consideration

the best thermal oxidation technique is determined for the following process of the IBC solar cell.