Superjunction power MOSFET
View Patent ↗An embodiment of an MOS device includes a semiconductor substrate of a first conductivity type, a first region of the first conductivity type having a length L acc and a net active dopant concentration of about N first , a pair of spaced-apart body regions of a second opposite conductivity type and each having a length L body and a net active dopant concentration of about N second , channel regions located in the spaced-apart body regions, source regions of the first conductivity type located in the spaced-apart body regions and separated from the first region by the channel regions, an insulated gate overlying the channel regions and the first region, and a drain region of the first conductivity type located beneath the first region. In an embodiment, (L body *N second )=k 1 *(L acc *N first ), where k 1 has a value in the range of about 0.6≦k 1 ≦1.4.
1. A metal oxide semiconductor (MOS) device, comprising:
a semiconductor substrate of a first conductivity type having an upper surface;
a first doped region of the first conductivity type that extends downwardly from the upper surface;
a gate overlying the first doped region and having a gate dielectric on the upper surface, an overlying dielectric layer on the gate dielectric, and a gate conductor, wherein a lateral extent of the gate extends beyond the first doped region and over portions of second doped regions that are laterally adjacent to the first doped region at the upper surface;
the second doped regions of a second opposite conductivity type extending downwardly from the upper surface and initially formed in the substrate beyond the lateral extent of the gate, wherein the first doped region and the second doped regions meet under the gate after exposure to a high temperature drive process, and wherein a charge equality condition is present in the first doped region and the second doped regions because a net active impurity concentration N first in the first doped region of lateral length L first and a net active impurity concentration N second in the second doped regions of lateral length L second satisfy a first relationship (N second *L second )=k 1 *(N first *L first ), where k 1 has a value in a range of about 0.6<k 1 <1.4, and also satisfy a second relationship that a depth of the first doped region is about equal to a depth of the second doped regions; and
a drain region of the first conductivity type located in the semiconductor substrate beneath the first doped region and the second doped regions, wherein the drain region is separated from the first doped region and the second doped regions by a portion of the semiconductor substrate that overlies the drain region and is beneath the first doped region and the second doped regions, and wherein the charge equality condition is not present in the portion of the semiconductor substrate that overlies the drain region and is beneath the first doped region and the second doped regions.
2. The device of claim 1 , further comprising:
first dielectric spacers on lateral edges of the gate conductor.
3. The device of claim 1 , further comprising:
source regions of the first conductivity type in the second doped regions.
4. The device of claim 3 , further comprising:
body contact regions of the second conductivity type in the second doped regions, wherein the body contact regions are located between the source regions.
5. The device of claim 4 , further comprising:
an electrically conductive barrier layer material on the source regions and the body contact regions.