P-CHANNEL POWER MOSFET
In characteristic test measurements of double-gate-in-trench p-channel power MOSFETs each having a p + polysilicon gate electrode and a p + field plate electrode in a trench, which were fabricated according to common design techniques, it has been found that, under conditions where a negative gate bias is applied continuously at high temperature with respect to the substrate, an absolute value of threshold voltage tends to increase steeply after the lapse of a certain period of stress application time. To solve this problem, the present invention provides a p-channel power MOSFET having an n-type polysilicon linear field plate electrode and an n-type polysilicon linear gate electrode in each trench part thereof.
1 . A p-channel power MOSFET comprising:
(a) a silicon-based semiconductor substrate having first and second principal surface sides; and
(b) a multiplicity of linear trenches disposed in the first principal surface side;
wherein each of the linear trenches includes:
(b1) an n-type polysilicon linear field plate electrode; and
(b2) an n-type polysilicon linear gate electrode disposed over and along the n-type polysilicon linear field plate electrode.
2 . The p-channel power MOSFET according to claim 1 ,
wherein the second principal surface side of the silicon-based substrate is provided with a p-type silicon single-crystal substrate region.
3 . The p-channel power MOSFET according to claim 2 ,
wherein the first principal surface side of the silicon-based semiconductor substrate is provided with a p-type silicon epitaxial region having a dopant concentration lower than that of the p-type silicon single-crystal substrate region.
4 . The p-channel power MOSFET according to claim 3 ,
wherein the second principal surface side of the silicon-based semiconductor substrate is provided with a metal drain electrode.
5 . The p-channel power MOSFET according to claim 4 ,
wherein the n-type polysilicon linear field plate electrode and the n-type polysilicon linear gate electrode are electrically coupled to each other.
6 . The p-channel power MOSFET according to claim 5 ,
wherein the n-type polysilicon linear field plate electrode and the n-type polysilicon linear gate electrode are coupled mutually outside each linear trench.
7 . The p-channel power MOSFET according to claim 6 ,
wherein the n-type polysilicon linear field plate electrode and the n-type polysilicon linear gate electrode are coupled mutually via a metal wiring line outside each linear trench.
8 . The p-channel power MOSFET according to claim 7 ,
wherein the p-channel power MOSFET is arranged for motor driving use.
9 . The p-channel power MOSFET according to claim 8 ,
wherein the p-channel power MOSFET is arranged for use as a low-threshold-voltage device.
10 . A p-channel power MOSFET comprising:
(a) a silicon-based semiconductor substrate having first and second principal surface sides; and
(b) a multiplicity of linear trenches disposed in the first principal surface side;
wherein each of the linear trenches includes:
(b1) an n-type polysilicon linear field plate electrode; and
(b2) a p-type polysilicon linear gate electrode disposed over and along the n-type polysilicon linear field plate electrode.
11 . The p-channel power MOSFET according to claim 10 ,
wherein the second principal surface side of the silicon-based substrate is provided with a p-type silicon single-crystal substrate region.
12 . The p-channel power MOSFET according to claim 11 ,
wherein the first principal surface side of the silicon-based semiconductor substrate is provided with a p-type silicon epitaxial region having a dopant concentration lower than that of the p-type silicon single-crystal substrate region.
13 . The p-channel power MOSFET according to claim 12 ,
wherein the second principal surface side of the silicon-based semiconductor substrate is provided with a metal drain electrode.
14 . The p-channel power MOSFET according to claim 13 ,
wherein the n-type polysilicon linear field plate electrode and the p-type polysilicon linear gate electrode are electrically coupled to each other.
15 . The p-channel power MOSFET according to claim 14 ,
wherein the n-type polysilicon linear field plate electrode and the p-type polysilicon linear gate electrode are coupled mutually outside each linear trench.
16 . The p-channel power MOSFET according to claim 15 ,
wherein the n-type polysilicon linear field plate electrode and the p-type polysilicon linear gate electrode are coupled mutually via a metal wiring line outside each linear trench.
17 . The p-channel power MOSFET according to claim 16 ,
wherein the p-channel power MOSFET is arranged for motor driving use.
18 . The p-channel power MOSFET according to claim 17 ,
wherein the p-channel power MOSFET is arranged for use as a low-threshold-voltage device.