NOVELTY - The method comprises flowing (510) a processing gas into a diffuser region between a backing plate and a showerhead of the deposition chamber, flowing (515) the processing gas through holes in the showerhead and into a process volume between the showerhead and a substrate support in the deposition chamber, igniting (520) a plasma in the process volume, back-flowing (525) gas ions formed in the plasma through the holes in the showerhead and into the diffuser region, and mixing (530) the gas ions and the processing gas in the diffuser region.    USE - The method is useful for forming a microcrystalline silicon layer on a substrate in a deposition chamber for manufacturing a photovoltaic solar cell.    ADVANTAGE - The method is capable of effectively and uniformly forming the microcrystalline silicon layer on the substrate in the deposition chamber of the photovoltaic solar cell with less number of processing steps thus improving the conversion efficiency and reducing the manufacturing cost of the solar cell.    DETAILED DESCRIPTION - The method comprises flowing (510) a processing gas into a diffuser region between a backing plate and a showerhead of the deposition chamber, flowing (515) the processing gas through holes in the showerhead and into a process volume between the showerhead and a substrate support in the deposition chamber, igniting (520) a plasma in the process volume, back-flowing (525) gas ions formed in the plasma through the holes in the showerhead and into the diffuser region, mixing (530) the gas ions and the processing gas in the diffuser region, re-flowing the gas ions and processing gas through the holes in the showerhead and into the process volume, cycling the flow of processing gas, initiating the deposition chamber by flowing hydrogen into the process volume, pressurizing the chamber to 6-10 Torr, and depositing a microcrystalline silicon layer on the substrate. The cycling step includes flowing the processing gas for 1-15 seconds after igniting the plasma, and stopping the flow of processing gas for 50-65 seconds, where the cycling occurs 10-20 times. The step of back-flowing the gas ions comprises decreasing the flow of processing gas to allow the gas ions to back-flow through the holes in the showerhead and into the diffuser region. The processing gas has a flow rate of 750-1300 seem. The step of igniting the plasma comprises applying a radio frequency power to the deposition chamber at 5000 W.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a method of forming a microcrystalline silicon layer on a substrate in a deposition chamber.    Flowing a processing gas into a diffuser region between a backing plate and a shower head of the deposition chamber (510)    Flowing the processing gas through holes in the showerhead and into a process volume between the showerhead and a substrate support in the deposition chamber (515)    Igniting a plasma in the process volume (520)    Back-flowing gas ions formed in the plasma through the holes in the showerhead and into the diffuser region (525)    Mixing the gas ions and the processing gas in the diffuser region. (530)