Electronic device comprising a trench gate field effect device

Abstract

A trench gate field effect device has a semiconductor body (,) with a trench (,) extending into a first major surface (,) so as to define a regular array of polygonal source cells (,). Each source cell contains a source region (,) and a body region (,) with the body regions separating the source regions from a common further region (,). A gate (G) extends within and along said trench (,) for controlling a conduction channel through each of the body regions. Each source cell (,) has a central semiconductor region (,) which is more highly doped than said body regions, is of opposite conductivity type to the further region and forms a diode with the further region. Each source cell (,) has an inner trench boundary (,) and an outer polygonal trench boundary (,) with the inner trench boundary bounding a central subsidiary cell (,) containing the central semiconductor region (,). A plurality of trench portions (,) radiate outwardly from the inner trench boundary (,) to the outer trench boundary (,) The trench portions separate the area between the inner and outer trench boundaries into a plurality of segments each having one side longer than another. Each segment forms a subsidiary source cell (,).