In-line hot-wire chemical vapor deposition of silicon-based coatings

Deposition of thin films by thermal activation of the gas phase via hot wires has the advantage of low system requirements and easy scale-up. To investigate the up-scaling of hot-wire chemical vapor deposition an in-line system with seven vacuum chambers including three hot-wire systems has been established. On areas up to 500 mm x 600 mm intrinsic hydrogenated silicon films have been deposited with in-line processing. Using design of experiments (DoE), we have investigated the combined influence of the factors silane flow, pressure, wire temperature Twire and film thickness on deposition rate, microstructure factor R*, and gas phase activation, respectively. Results show that it is possible to combine good microstructure of a-Si:H films with deposition rates greater than or equal 1.5 nm/s and good thickness uniformity. The properties of the deposited films were characterized for applications such as passivation of crystalline silicon solar cells and fabrication of thin film solar cells.