Passivation of laser grooved buried contacts (LGBC) solar cells with silicon oxide or silicon nitride grown by a remote sputtering deposition system

Silicon nitride (SiN
x
) and Silicon Oxide (SiO
2
) thin films have been deposited by a new remote plasma deposition system HiTUS (High Target Utilisation Sputtering). The remote plasma geometry allows, pseudo separation of plasma/target-bias parameters, avoiding ion bombardment, and effectively eliminates poisoning, making it an attractive option for stable reactive sputtering of important electronic and photovoltaic films including SiN
x
or SiO
2
for passivation of the front surface or as antireflective coating. The SiN
x
(SiO
2
) thin films are grown by reactive sputtering from a silicon target in an Ar/N
2
(O
2
) atmosphere, negating the use of silane gas in difference to the more commonly used PECVD method. A deposition rates up to 7.8 Å/s have been obtained (see Fig.1).The deposition rate increase from 4 Å/s up to 7Å/s at 100% RF bias power with an error of ±5%. A good control of the refractive index (between 1.7 up to 2.3) has also been found. Photo conductive measurements by a WCT-100 were performed on silicon wafer after each thermal process to measure the effective lifetime of p-type crystalline silicon wafer Boron doped ≪100≫ to measure the effective lifetime of the minority carriers. Carrier lifetime up to 30 microseconds have been measured on c-Si wafer passivated by SiO
2
. We have shown that the SiO
2
and SiNx thin film have high passivation quality making the HiTUS a viable new sputtering system for deposition of antireflective coatings for solar cells production.