VHF plasma processing for in-line deposition systems

Abstract

The production of amorphous and microcrystalline silicon (μc-Si) for thin film transistors and related applications requires large area, high-deposition rate plasma reactors. Increasing the excitation frequency into the VHF range has demonstrated higher productivity of deposition and etch systems. However, the use of VHF for large area systems leads to some problems. For example, the uniformity of the deposition decreases due to generation of standing and evanescent waves on the electrode surface. This paper demonstrates the deposition of μc-Si films on large area substrates employing a new linear plasma source (line source) with multipoint power feeding in combination with a continuous deposition on moving substrates. By using a source of 550 mm in length and an excitation frequency of 81.36 MHz, deposition rates up to 4 μm h −1 for μc-Si and film thickness inhomogeneities of less than ±5% were achieved. Experimental results and electronic properties of μc-Si films deposited with the new method will be discussed in relation to the deposition parameters and the process conditions.