Plasma enhanced chemical vapor deposited silicon nitride as a gate dielectric film for amorphous silicon thin film transistors—a critical review

Abstract Plasma enhanced chemical vapor deposited (PECVD) silicon nitride (SiN x ) is the dominate gate dielectric material for the amorphous silicon (a-Si:H) thin film transistors (TFTs) today. In this paper, the author critically reviewed several major issues in this field. Two subjects are included in the discussion: effects of SiN x gate dielectric material properties to TFT devices and the large area PECVD SiN x processes. The first subject includes: the bulk film characteristics, a-Si:H TFT performance related to the SiN x /a-Si:H interface properties, such as morphology and band gaps, the dual SiN x gate dielectric structure, and the influence of a-Si:H deposition processes to transistor performance. The second subject is concentrated on the large area PECVD SiN x processes which include uniformity, film characteristics, etc. At the end, a unified relationship between the TFT's threshold voltage and the SiN x refractive index is presented. In the conclusion, relationships among SiN x process, material, and TFT device characteristics are summarized.