Patent ID: 7998785
Filing Date: 2011-08-16
Classification: C23C,H01J,H01L

Abstract:
1. A method of forming a film of an amorphous material on a substrate by deposition from a plasma, the method comprising: placing the substrate in an enclosure, continuously introducing into the enclosure a film precursor gas at a flow rate, and extracting unreacted and dissociated gas from the enclosure so as to provide a low pressure in the enclosure, introducing microwave energy into the gas within the enclosure as a sequence of pulses at a given frequency and power level, to produce a plasma therein by distributed electron cyclotron resonance (DECR) and cause the material to be deposited from the plasma on the substrate, wherein the said frequency and/or power level is altered during the course of deposition of material, so as to cause the bandgap to vary over the thickness of the deposited material.