Protection transistor with improved edge structure

摘要

A metal-oxide-semiconductor protection transistor is formed in an active region of a semiconductor layer. The active region includes source and drain diffusion layers, which may be partly silicided, and a body region. A gate electrode extends across the active region above the body region. The breakdown voltage in the edge areas of the active regions is increased by increasing the gate length in the edge areas, by increasing the width of the active region below the gate electrode, or by increasing the non-silicided length of the source and drain diffusion layers in the edge areas. The edge areas of the active region are thereby protected from thermal damage during electrostatic discharges.