Vertical trench-gate power MOSFET having stripe geometry and high cell density

摘要

A vertical trench-gated power MOSFET includes MOSFET cells in the shape of longitudinal stripes. The body diffusion of each cell contains a relatively heavily-doped region which extends parallel to the length of the cell and contacts an overlying metal source/body contact layer at specific locations. In one embodiment, the contact is made at an end of the cell. In another embodiment, the contact is made at intervals along the length of the cell. In addition, the power MOSFET contains diode cells placed at intervals in the array of cells. The diode cells contain diodes connected in parallel with the MOSFET cells and protect the gate oxide layer lining the trenches from damage due to large electric fields and hot carrier injection. By restricting the areas where the body contact is made and using the diode cells, the width of the MOSFET cells can be reduced substantially, thereby reducing the on-resistance of the power MOSFET.