Method of making a trench mosfet with heavily doped delta layer to provide low on-resistance

摘要

In a vertical trench MOSFET, a layer of increased dopant concentration is formed in a lightly-doped or "drift" region which separates the body region from the drain region of the MOSFET. The layer of increased dopant concentration denominated a "delta" layer, operates to spread out the current as it emerges from the channel of the MOSFET and thereby reduces the resistance of the MOSFET when it is turned on.