Industrial high-rate (≥ 4 nm/s) deposited silicon nitride with low surface recombination velocities under optimum antireflection coating conditions

High quality surface passivation has been obtained for silicon nitride films deposited at very high deposition rates of =4 nm/s. By extensive process optimization the mass density of our silicon nitride films was increased and the absorption in the UV part of the solar spectrum was reduced. These optimized silicon nitride films were deposited using a commercial inline industrial reactor employing the expanding thermal plasma (ETP) technique and with a nominal throughput of 960 wafers/hour. The low surface ecombination velocities of ~50-70 cm/s were obtained on 8.4 O cm p-type float zone crystalline silicon wafers for the commercially interesting refractive index range of 1.9-2.4. Combining the data on surface passivation with the calculated reflection and absorption losses shows that a good level of surface passivation can be obtained under optimal antireflection coating performance.