N-well/P-well strap structures
View Patent ↗Embodiments of N-well or P-well strap structures are disclosed with lower space requirements achieved by forming the strap on both sides of one or more floating polysilicon gate fingers.
1. A method comprising:
forming a well in a semiconductor substrate;
forming a first active device in the well;
forming a strap in the well and separated from the first active device, wherein the strap comprises first and second diffusion regions on opposite sides of a floating polysilicon finger, and wherein the strap further comprises first and second taps that connect respectively to the first and second diffusion regions on opposite sides of the floating polysilicon finger;
forming a first dummy polysilicon finger between the first active device and the strap;
forming a second active device in the well on an opposite side of the strap from the first active device; and
forming a second dummy polysilicon finger between the second active device and the strap.
2. The method of claim 1 , wherein the first active device is an MOS transistor.
3. The method of claim 1 further comprising:
forming a shallow trench isolation region that surrounds the first active device and the strap.
4. The method of claim 3 , wherein the shallow trench isolation region surrounds the second active device.
5. The method of claim 1 , wherein the first active device comprises a first polysilicon gate finger, and wherein the second active device comprises a second polysilicon gate finger.
6. The method of claim 5 , wherein the first active device further comprises first source and drain regions, and wherein the second active device further comprises second source and drain regions.
7. The method of claim 1 further comprising:
forming a shallow trench isolation region, wherein the first and second dummy polysilicon fingers are located above portions of the shallow trench isolation region.
8. The method of claim 1 , wherein the well is doped with N-type dopants.
9. The method of claim 2 , wherein the second active device is an MOS transistor.
10. A method comprising:
forming a well in a semiconductor substrate;
forming a first active device in the well;
forming a strap in the well and separated from the first active device, wherein the strap comprises a diffusion region, a floating polysilicon finger, and a tap connecting to the diffusion region on one side of the floating polysilicon finger;
forming a first dummy polysilicon finger on the well between the first active device and the strap;
forming a second active device in the well on an opposite side of the strap from the first active device; and
forming a second dummy polysilicon finger on the well between the second active device and the strap.
11. The method of claim 10 , wherein the first active device is an MOS transistor.
12. The method of claim 10 , wherein a plurality of taps connect to the diffusion region.
13. The method of claim 10 further comprising:
forming a shallow trench isolation region surrounding the first active device and the strap.
14. The method of claim 13 , wherein the shallow trench isolation region surrounds the second active device.
15. The method of claim 10 , wherein the first active device comprises a first polysilicon gate finger, and wherein the second active device comprises a second polysilicon gate finger.
16. The method of claim 15 , wherein the first active device further comprises first source and drain regions, and wherein the second active device further comprises second source and drain regions.
17. The method of claim 10 further comprising:
forming a shallow trench isolation region, wherein the first and second dummy polysilicon fingers are located above portions of the shallow trench isolation region.
18. The method of claim 11 , wherein the second active device is an MOS transistor.