Termination for trench MIS device having implanted drain-drift region
View Patent ↗A trench MIS device is formed in a semiconductor die that contains a P-epitaxial layer that overlies an N+ substrate and an N-epitaxial layer. In one embodiment, the device includes a drain-drift region that extends from the bottom of the trench to the N-epitaxial layer. A termination region of the die includes a half-trench at an edge of the die and an N-type region that extends from a bottom of the half-trench to the substrate. An insulating layer and an overlying metal layer extend from the surface of the epitaxial layer into the half-trench. Preferably, the elements of the termination region are formed during the same process steps that are used to form the active elements of the device.
1. A semiconductor die comprising a trench MIS device, said die comprising a first layer of a first conductivity type and a second layer of a second conductivity type overlying said first layer, said die comprising a termination region comprising:
a half-trench formed in said second layer adjacent an edge of said die;
a region of said first conductivity type extending from a bottom of said half-trench to said first layer,
an insulating layer extending from said bottom of said half-trench, up a wall of said half-trench and over a surface of said second layer; and
a source metal layer over said insulating layer, said source metal layer extending from a location within said half-trench and over a surface of said second layer, said source metal layer being in electrical contact with a source region of said MIS device, an edge of said source metal layer in said half-trench being laterally spaced from said edge of said die.
2. The die of claim 1 further comprising:
a trench located in said second layer in an active region of said die;
a drain-drift region of said first conductivity type extending from a bottom of said trench to said first layer; and
a conductive gate in said trench,
wherein said insulating layer extends from a location above said trench and into said half-trench.
3. The die of claim 2 wherein said source region is located adjacent said trench.
4. The die of claim 1 comprising a metal edge segment located in said half-trench adjacent said edge of said die, said metal edge segment being electrically isolated from said source metal layer and being in electrical contact with said region of first conductivity type.
5. The die of claim 4 wherein said metal edge segment is in electrical contact with said region of first conductivity type through an opening in said insulating layer at said bottom of said half-trench.
6. The die of claim 5 comprising a heavily-doped region of said first conductivity type within said region of first conductivity type and in contact with said metal edge segment.
7. The die of claim 1 wherein said second layer comprises an epitaxial layer of said second conductivity type.
8. The die of claim 7 wherein said first layer comprises a substrate and an epitaxial layer of said first conductivity type overlying said substrate.