a-Si thin film transistors using dilute-gas plasma-enhanced chemical vapor deposition

Dilute-gas plasma-enhanced chemical vapor deposition (PECVD) has been used to fabricate high-quality amorphous silicon (a-Si) thin film transistors (TFTs) which are suitable for active-matrix liquid-crystal displays. All PECVD layers were deposited using silane diluted to 2% in He or H/sub 2/, which greatly reduces the explosion hazards associated with silane. The quality of a-Si produced by low-power, He-diluted silane at rates of approximately 1 AA/s is comparable to that made with pure silane. He dilution has also been utilized to control the properties of SiO/sub 2/ and SiN/sub x/ insulators deposited by PECVD. Using this approach, the effects of several material aspects on TFT characteristics were examined. The TFT structures were bottom-gate, inverted-staggered devices with deposited n/sup +/ microcrystalline silicon contacts.