| 摘要 |
In a vertical MOSFET comprises: a semiconductor layer (1, 2, 9, 10) having first and second surfaces opposite to each other and trenches (6) formed on the first surface; trench gates (8) formed in the trenches; a unit cell formed in a region of the semiconductor layer surrounded by the trench gates, the unit cell comprising a base layer (9) and a source layer (10) formed on the base layer and having the first surface as a principal semiconductor surface, the unit cell having a contact hole (12) formed on a center of the principal semiconductor surface and extending from the principal semiconductor surface through the source layer to an inside of the base layer; a contact (17) formed in the contact hole; a source electrode (18) formed on the contact; and a drain electrode (19) formed on the second surface, the contact is formed to a depth different to a peak depth which is a position having a maximum impurity-concentration in a depth direction of the base layer. The unit call further comprises a base contact layer (14) formed within the base layer so as to enclose a bottom of the contact and to bring the base contact layer into contact with the bottom of the contact.
|
