Super trench MOSFET including buried source electrode and method of fabricating the same
First Claim
1. A trench-gated transistor formed in a semiconductor die, said transistor comprising:
- an arrangement of annular trenches in the die, each of said trenches being separated from an adjacent trench by an annular mesa, said trenches comprising a gate electrode, said die comprising a doped region;
a source metal layer and a gate metal layer, said source metal layer being in electrical contact with said doped region, said gate metal layer being in electrical contact with said gate electrode, said gate metal layer comprising a plurality of gate metal legs that extend radially outward from a central area toward a perimeter of said die, said source metal layer comprising a plurality of sections located between said gate metal legs.
6 Assignments
0 Petitions
Accused Products
Abstract
In a trench MOSFET, the lower portion of the trench contains a buried source electrode, which is insulated from the epitaxial layer and semiconductor substrate but in electrical contact with the source region. When the MOSFET is in an “off” condition, the bias of the buried source electrode causes the “drift” region of the mesa to become depleted, enhancing the ability of the MOSFET to block current. The doping concentration of the drift region can therefore be increased, reducing the on-resistance of the MOSFET. The buried source electrode also reduces the gate-to-drain capacitance of the MOSFET, improving the ability of the MOSFET to operate at high frequencies. The substrate may advantageously include a plurality of annular trenches separated by annular mesas and a gate metal layer that extends outward from a central region in a plurality of gate metal legs separated by source metal regions.
-
Citations
22 Claims
-
1. A trench-gated transistor formed in a semiconductor die, said transistor comprising:
-
an arrangement of annular trenches in the die, each of said trenches being separated from an adjacent trench by an annular mesa, said trenches comprising a gate electrode, said die comprising a doped region; a source metal layer and a gate metal layer, said source metal layer being in electrical contact with said doped region, said gate metal layer being in electrical contact with said gate electrode, said gate metal layer comprising a plurality of gate metal legs that extend radially outward from a central area toward a perimeter of said die, said source metal layer comprising a plurality of sections located between said gate metal legs. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
-
Specification