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

Silicon nitride (SiNx) and Silicon Oxide (SiO2) 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 SiNx or SiO2 for passivation of the front surface or as antireflective coating. The SiNx (SiO2) thin films are grown by reactive sputtering from a silicon target in an Ar/N2 (O2) 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 SiO2. We have shown that the SiO2 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.