Plasma processing in the fabrication of amorphous silicon thin-film-transistor arrays

Abstract

Plasma deposition and etching are two critical processes in the fabrication of the arrays of thin-film transistors (TFTs) in active-matrix liquid crystal displays. The processes fulfill three important production requirements: suitability for use at relatively low substrate temperatures, suitability for large substrates, and high throughput capability. We present an overview of our recent studies on the plasma-processing aspects of the fabrication of large-area arrays of TFTs in which use is made of thin films of amorphous silicon containing hydrogen (a-Si:H). Subjects covered include the plasma-enhanced chemical vapor deposition (PECVD) of a-Si:H films, SiN <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> films, and heavily phosphorus-doped Si films; the influence of the films on TFT characteristics; associated plasma-etching and edge-profile aspects; plasma-etching-induced damage to TFTs and repair of the damage; and equipment aspects.