Thyristor-based device having extended capacitive coupling

• US 6,583,452 B1
• Filed: 12/17/2001
• Issued: 06/24/2003
• Est. Priority Date: 12/17/2001
• Status: Expired due to Fees

• Current Assignee: T-Ram, LLC
• Original Assignee: T-Ram, Inc.
• Inventors: Cho, Hyun-jin, Horch, Andrew, Robins, Scott, Nemati, Farid
• Primary Examiner(s): Nguyen, Tuan H.
• Application Number:
  US10/023,060
• Time in Patent Office: 554 Days
• Field of Search: 257/107, 257/124, 257/125, 257/139, 257/140, 257/146, 257/147, 257/133, 438/133, 438/135
• US Class Current: 257/107
• CPC Class Codes: H01L 27/0817 Thyristors only
• CPC Class Codes: H01L 29/42308 Gate electrodes for thyristors
• CPC Class Codes: H01L 29/74 Thyristor-type devices, e.g. having four-zone regenerative action two-terminal thyristors H01L29/87
• CPC Class Codes: H01L 29/7436 Lateral thyristors

Abstract

A thyristor-based semiconductor device has a thyristor that exhibits increased capacitive coupling between a conductive structure and a portion of a thyristor. According to an example embodiment of the present invention, the thyristor-based semiconductor device is manufactured having an extended portion that is outside a current path through the thyristor and that capacitively couples a conductive structure to a portion of the thyristor for controlling the current through the path. In one particular implementation, the extended portion extends from a base region of the thyristor and is outside of a current path through the base region and between an adjacent base region and an adjacent emitter region. A gate is formed capacitively coupled to the base region via the extended portion. In this manner, the control of the thyristor with the gate exhibits increased capacitive coupling, as compared to the control without the extended portion.

Claims

1. A semiconductor device comprising:

a thyristor having contiguous regions including at least two contiguous regions of different polarity, a first one of the contiguous regions having a portion in a current path traversing two regions of the thyristor other than the first one of the contiguous regions and having an extended portion arranged outside the current path; and

a conductive structure facing and capacitively coupled to the extended portion of the first one of the contiguous regions, the conductive structure being adapted to control current passing through the thyristor via the capacitive coupling.

2. The device of claim 1, wherein the extended portion is arranged immediately adjacent to only one contiguous region.

3. The device of claim 1, wherein the extended portion is arranged immediately adjacent to only one contiguous region and has a polarity that is common to the immediately-adjacent contiguous region.

4. The device of claim 1, wherein at least one of the contiguous regions is oriented along a first generally planar area and at least another one of the contiguous regions is oriented along a second generally planar area that is non-planar with respect to the first generally planar area.

5. The device of claim 4, wherein the first generally planar area includes the extended portion, and wherein the conductive structure faces the first generally planar area.

6. The device of claim 1, wherein the conductive structure faces at least two contiguous regions.

7. The device of claim 1, wherein the portion of the first contiguous region in the current path is adapted to switch between a pass state and a blocking state in response to a signal capacitively coupled from the conductive structure via a surface area between the portion of the first contiguous region in the current path and the conductive structure, and wherein the extended portion is adapted to increase the surface area between the conductive structure and the first contiguous region, relative to the surface area between the portion of the first contiguous region in the current path and the conductive structure.

8. The device of claim 1, wherein the extended portion facing the conductive structure includes a non-planar surface.

9. The device of claim 1, wherein the conductive structure includes at least two generally planar sides and wherein the first one of the contiguous regions faces the conductive structure on both of the at least two generally planar sides of the conductive structure.

10. The semiconductor device of claim 1, further comprising a semiconductor substrate having a transistor formed therein, wherein one of the contiguous regions of the thyristor is coupled to a source/drain region of the transistor.

11. The semiconductor device of claim 10, wherein the extended portion is formed in the substrate.

12. The semiconductor device of claim 10, wherein the extended portion is formed over the substrate.

13. The device of claim 1, wherein the thyristor is a thin capacitively coupled thyristor.

14. The semiconductor device of claim 1, the thyristor being adapted to respond to at least one control voltage presented to the gate by passing current through at least one of the contiguous regions of each of the first and second sets.

15. The semiconductor device of claim 1, wherein the conductive structure includes a contiguous portion that encircles one of the contiguous regions of the thyristor.

16. The semiconductor device of claim 1, further comprising silicon on insulator (SOI) structure including a buried insulator layer, wherein at least one of the contiguous regions of the thyristor extends into the buried insulator layer.

17. The semiconductor device of claim 1, further comprising silicon on insulator (SOI) structure including a generally horizontal buried insulator layer having an opening therein and a pass gate having source/drain regions on the buried insulator layer, wherein the thyristor comprises:

a first emitter region extending below the buried insulator layer;

a first base region extending into the opening in the insulator layer and contiguously adjacent the first emitter region;

a second base region extending laterally on the insulator layer and contiguously adjacent the first base region, a portion of the second base region including the extended portion;

a second emitter region contiguously adjacent the second base region and including a source/drain region of the pass gate; and

wherein the conductive structure is formed over the second base region and extending laterally over the extended portion.

18. The semiconductor device of claim 1, further comprising a plurality of word lines having a dielectric formed thereon, at least one of the word lines including a gate of a pass gate that is coupled to the thyristor, wherein the thyristor extends over at least two of the word lines.

19. The semiconductor device of claim 1, wherein the conductive structure is adapted to capacitively couple a signal to control the current passing through the thyristor independently from any MOS inversion channel formation against the first contiguous region.

20. A memory array having a plurality of memory cells wherein at least one of the memory cells comprises:

a thyristor having contiguous regions including at least two contiguous regions of different polarity, a first one of the contiguous regions having a portion in a current path traversing two regions of the thyristor other than the first one of the contiguous regions and having an extended portion arranged outside the current path; and

a conductive structure facing and capacitively coupled to the extended portion of the first one of the contiguous regions, the conductive structure being adapted to control current passing through the thyristor via the capacitive coupling.

21. A memory cell comprising:

a thin capacitively-coupled thyristor body having an anode end portion including an N-doped base region and a P+ doped emitter region, and having a cathode end portion including a P-doped base region and an N+ doped emitter region, a first one of the base regions having a portion in a current path extending between the other base region and the emitter at the thyristor end portion that includes the first one of the base regions and having an extended portion outside the current path and extended from the thyristor body;

a gate dielectric on the extended portion of the first one of the base regions;

a control gate on the gate dielectric, capacitively coupled to the extended portion via the gate dielectric and adapted to control the thyristor via the capacitive coupling; and

a pass gate transistor having a gate and two source/drain regions, one of the source/drain regions being electrically coupled to one of the emitter regions.

22. The memory cell of claim 21, wherein the source/drain region not coupled to the emitter region is coupled to a bitline, wherein the gate of the pass gate transistor forms a first word line, wherein the control gate forms a second word line and wherein the emitter region not electrically coupled to the source/drain region is electrically coupled to a power source, the memory cell being adapted to store an electrical representation of data via inputs from the bitline and wordlines.

23. A memory array having a plurality of memory cells, at least one of the memory cells comprising:

a thin capacitively-coupled thyristor body having an anode end portion including an N-doped base region and a P+ doped emitter region, and having a cathode end portion including a P-doped base region and an N+ doped emitter region, a first one of the base regions having a portion in a current path extending between the other base region and the emitter at the thyristor end portion that includes the first one of the base regions and having an extended portion outside the current path and extended from the thyristor body;

a gate dielectric on the extended portion of the first one of the base regions;

a control gate on the gate dielectric, capacitively coupled to the extended portion via the gate dielectric and adapted to control the thyristor via the capacitive coupling; and

a pass gate transistor having a gate and two source/drain regions, one of the source/drain regions being electrically coupled to one of the emitter regions.