Problems in Large Size Amorphous Silicon Plate Manufacturing

Abstract

ABSTRACTThe growing aSi:H based component industry needs large PECVD machines for high throughput coating of flat substrates up to 1 meter in size. Deposition uniformity can be affected by gas depletion in diffusion and laminar gas flow geometries. Deposition rate is shown to be in conflict with large size uniformity. Main uniformity problems are found to originate from uneven RF voltage distribution, the effect is shown to be amplified near plasma equilibrium transitions. Contamination, a key factor for production quality, is controlled by the hot pressurized plasma box by both reducing unwanted background gas near UHV level and by allowing systematic fast plasma cleaning without machine corrosion or post contamination. Powder formation and dynamic is discussed based on several novel experiments and powder formation threshold is shown to be pushed away if the plasma is made intermittent.