Superjunction trench device and method

A trench-type semiconductor device embodying a superjunction structure, the device comprising:

• first spaced-apart regions of a first semiconductor material having a first conductivity type and a first lattice constant;
• second spaced-apart regions of a second semiconductor material interleaved with the first space-apart regions, and having a second different conductivity type and a second different lattice constant so that the second semiconductor material in the second regions is strained with respect to the first semiconductor material in the first regions and one or more PN junctions exists therebetween;
• and
• a further region of substantially relaxed semiconductor material in contact with the first and second spaced-apart interleaved regions and having an outer surface,
• a trench in the further region extending from the outer surface substantially to the first and second spaced-apart interleaved regions;
• a strained semiconductor material on at least the side-walls of the trench;
• a gate dielectric over the strained semiconductor material;
• a gate in contact with the gate dielectric, spaced apart thereby from the strained semiconductor material;
• and
• one or more source regions communicating with the strained semiconductor material and separated from the first and second spaced-apart interleaved regions by a portion of the strained semiconductor material.

A semiconductor device formed on a substrate having an outer surface, the device comprising:

• first spaced-apart semiconductor regions of a first conductivity type and first mobility formed on the outer surface of the substrate;
• second semiconductor regions of a second opposite conductivity type and higher second mobility, interleaved with the first spaced-apart semiconductor regions on the outer surface of the substrate to form a superjunction structure;
• a first conductivity type body region of a third semiconductor having a third mobility formed over the superjunction structure, communicating with the superjunction structure and having an outer surface;
• a trench extending through the body region from the outer surface to communicate with the superjunction structure;
• and
• a fourth semiconductor region of a fourth mobility higher than the third mobility formed at least on the trench sidewalls.