Semiconductor device structures and related processes
View Patent ↗Improved highly reliable power RFP structures and fabrication and operation processes. The structure includes plurality of localized dopant concentrated zones beneath the trenches of RFPs, either floating or extending and merging with the body layer of the MOSFET or connecting with the source layer through a region of vertical doped region. This local dopant zone decreases the minority carrier injection efficiency of the body diode of the device and alters the electric field distribution during the body diode reverse recovery.
1. A semiconductor device structure, comprising:
a gate which is positioned in a first trench, and capacitively coupled to control vertical conduction from a first-conductivity-type source through semiconductor material which is adjacent to said trench;
recessed field plates, positioned in proximity to and capacitively coupled to said semiconductor material; said recessed field plates being positioned in respective second trenches; and
diffusions of a second conductivity type lying at least partially directly below said respective second trenches.
2. A semiconductor device structure, comprising:
a gate which is positioned in a first trench, and capacitively coupled to control vertical conduction from a first-conductivity-type source through semiconductor material which is adjacent to said trench;
recessed field plates, positioned in proximity to and capacitively coupled to said semiconductor material; said recessed field plates being positioned in respective second trenches; and
diffusions of a second conductivity type lying at least partially beneath said respective second trenches;
wherein said device further includes a layer of dopant concentration region of second-conductivity-type that extends from a source layer to at least one of said diffusions.
3. The semiconductor device structure of claim 1 , wherein at least one of said diffusions extends vertically and merges with a body layer of second-conductivity-type.
4. A semiconductor device structure, comprising:
a gate which is positioned in a first trench, and capacitively coupled to control vertical conduction from a first-conductivity-type source through semiconductor material which is adjacent to said trench;
recessed field plates, positioned in proximity to and capacitively coupled to said semiconductor material; said recessed field plates being positioned in respective second trenches; and
diffusions of a second conductivity type lying at least partially beneath said respective second trenches;
wherein said device further includes a layer of dopant concentration region of second-conductivity-type that extends from a source layer to at least one of said diffusions and at least one of said diffusions extends vertically and merges with a body layer of second-conductivity-type.
5. The semiconductor device structure of claim 1 , wherein the gate has a split poly configuration.
6. The semiconductor device structure of claim 1 , wherein at least one of the recessed field plates has a split poly configuration.
7. The semiconductor device structure of claim 1 , wherein both the gate and at least one of the recessed field plates have a split poly configuration.
8. The semiconductor device structure of claim 1 , wherein said first conductivity type is n-type.
9. The semiconductor device structure of claim 1 , wherein said gate is capacitively coupled to control vertical conduction to a drain diffusion of said first conductivity type.
10. A semiconductor device structure, comprising:
a semiconductor layer;
a gate which is positioned in a first trench within said semiconductor layer, and is capacitively coupled to control vertical conduction from a first-conductivity-type source through second-conductivity-type portions of said layer near said trench;
recessed field plates, positioned in proximity to and capacitively coupled to said semiconductor material; said recessed field plates being positioned in respective second trenches;
diffusion components of a second conductivity type lying at least partially directly below said respective second trenches;
whereby said diffusion components reduce depletion of said second-conductivity-type portions of said layer in the OFF state.
11. The semiconductor device structure of claim 10 , wherein said gate has a split poly configuration.
12. The semiconductor device structure of claim 10 , wherein at least one of said recessed field plates has a split poly configuration.
13. The semiconductor device structure of claim 10 , wherein both the gate and at least one of the recessed field plates have a split poly configuration.
14. The semiconductor device structure of claim 10 , wherein said diffusion components have a concentration sufficiently high to locally counterdope said semiconductor layer and thereby produce a second conductivity-type region below said second trench.
15. The semiconductor device structure of claim 10 , wherein said semiconductor layer is an epitaxial layer.