Patent ID: 8828859

Claim:
A method for forming a semiconductor film, the method comprising the steps of: setting a substrate between a first electrode that comprises a first upper electrode and a second upper electrode and a second electrode, wherein the first electrode and the second electrode are located in a reaction chamber, and the substrate is set so that the first upper electrode overlaps with the substrate and the second upper electrode does not overlap with the substrate, supplying a source gas to the reaction chamber; and generating plasma between the first electrode and the second electrode to form the semiconductor film over the substrate, wherein the plasma is generated by applying power to the first upper electrode and the second upper electrode in different frequencies so that a plasma density in a region which overlaps with the substrate is lower than a plasma density in a region which does not overlap with the substrate, and wherein the frequencies applied to the first upper electrode and the second upper electrode each are equal to or larger than 13.56 MHz and equal to or smaller than 100 MHz.