Advances in the deposition of microcrystalline silicon at high rate by distributed electron cyclotron resonance

Abstract

We report on the growth of microcrystalline silicon films at high rates (14 Å/s) in a MDECR plasma reactor. Our studies show that the growth process can be described by the same mechanisms as in RF deposition. However, the higher deposition rate achieved in MDECR leads to a higher substrate temperature requirement (225–250 °C) in order to allow hydrogen to diffuse within the film and induce its crystallization. Moreover we also found that microcrystalline silicon growth requires high microwave power (depletion mode) to produce enough atomic hydrogen and low sheath potential to limit ion bombardment. Combining these conditions we could achieve deposition rates up to 28 Å/s (limited by the silane flow rate) in films with a crystalline fraction of the order of 65% which is well adapted for solar cell applications.