A thin film MOS transistor and an active matrix liquid crystal display device

摘要

A thin film MOS transistor includes a silicon layer (202) whose thickness, at least in the channel region is less than 2500 ANGSTROM . The silicon layer may be a polycrystalline silicon layer and its thickness in the channel region may be less than its thickness in the source and drain regions. Such thin film MOS transistors may be used in active matrix liquid crystal display devices having a plurality of picture elements arranged in a matrix, each picture element having a thin film MOS transistor as a switching element.