Manufacture of trench-gate semiconductor devices

Abstract

A trench-gate semiconductor device, for example a MOSFET or IGBT, of compact geometry is manufactured with self-aligned masking techniques in a simple process with good reproducibility. The source region ( ) of the device is formed by introducing dopant ( ) into an area of the body region ( ) via a mask window ( ), diffusing the dopant to form a surface region ( ) that extends laterally below the mask ( ) at a distance (d) beyond the masking edge ( ) of the window ( ), and then etching the body ( ) at the window ( ) to form a trench ( ) for the trench-gate ( ) with a lateral extent (y) that is determined by the etching of the body ( ) at the masking edge ( ) of the window ( ). A portion of the surface region ( ) is left to provide the source region ( ) adjacent to the trench ( ). The invention permits the etch edge definition for the trench ( ) to be better controlled by using the masking edge ( ) of a well-defined mask ( ), as compared with the less well defined edges that tend to result from the use of a side-wall extension in prior-art processes.