| 摘要 |
<p>In order to form an device in each of a vertical trench gate MOSFET region (21) and control lateral planar gate MOSFET region (22) of a semiconductor substrate, firstly, a trench (33) is formed in the semiconductor substrate in the vertical trench gate MOSFET region (21). Next, a first gate oxide film (7a) is formed along the internal wall of the trench (33). Next, the trench (33) is filled with a polysilicon film (6a) on the first gate oxide film (7a). Next, a LOCOS oxide film (11) is formed in a region isolating the devices. Next, a second gate oxide film (7b) is formed on the semiconductor substrate in the lateral planar gate MOSFET region (22). By so doing, advantages are achieved in that an increase in the number of steps is suppressed, the gate threshold voltage of an output stage MOSFET is higher than the gate threshold voltage of a control MOSFET, the thickness of the LOCOS oxide film (11) does not decrease, and no foreign object residue remains inside the trench (33).</p> |
