Thyristor-based device having dual control ports

• US 6,965,129 B1
• Filed: 11/06/2002
• Issued: 11/15/2005
• Est. Priority Date: 11/06/2002
• Status: Expired due to Fees

• Current Assignee: T-Ram, LLC
• Original Assignee: T-Ram, Inc.
• Inventors: Horch, Andrew, Robins, Scott, Nemati, Farid
• Primary Examiner(s): Flynn, Nathan J.
• Assistant Examiner(s): Forde, Remmon R.
• Application Number:
  US10/288,953
• Time in Patent Office: 1,105 Days
• Field of Search: 257/109, 257/119, 257/107, 257/130, 257/175, 257/176
• US Class Current: 257/109
• CPC Class Codes: G11C 11/39 using thyristors or the avalanche or negative resistance type, e.g. PNPN, SCR, SCS, UJT
• CPC Class Codes: H01L 27/1027 Thyristors
• CPC Class Codes: H01L 27/105 including field-effect components
• CPC Class Codes: H01L 29/7436 Lateral thyristors
• CPC Class Codes: H10B 10/10 SRAM devices comprising bipolar components
• CPC Class Codes: H10B 12/00 Dynamic random access memory [DRAM] devices
• CPC Class Codes: H10B 99/00 Subject matter not provided for in other groups of this subclass

Abstract

Switching operations, such as those used in memory devices, are enhanced using a thyristor-based semiconductor device adapted to switch between a blocking state and a conducting state. According to an example embodiment of the present invention, a thyristor-based semiconductor device includes a thyristor having first and second base regions coupled between first and second emitter regions, respectively. A first control port capacitively couples a first signal to the first base region, and a second control port capacitively couples a second signal to the second base region. Each of the first and second signals have a charge that is opposite in polarity, and the opposite polarity signals effect the switching of the thyristor at a lower power, relative to the power that would be required to switch the thyristor having only one control port. In this manner, power consumption for a switching operation can be reduced, which is useful, for example, to correspond with reduced power supplied to other devices in a semiconductor device employing the thyristor.

Claims

1. A semiconductor device comprising:

a switching circuit having first and second base regions coupled between first and second emitter regions;

a first control port configured and arranged to capacitively couple a first signal to at least the first base region; and

a second control port configured and arranged to capacitively couple a second signal to at least the second base region, wherein the switching circuit is adapted to switch between a blocking state and a conducting state in response to at least one of the first and second signals.

2. The semiconductor device of claim 1, wherein the first and second signals are opposite in polarity.

3. The semiconductor device of claim 2, wherein the switching circuit is adapted to switch between a blocking state and a conducting state in response to both of the signals.

4. The semiconductor device of claim 1, wherein the switching circuit is adapted to switch between a blocking state and a conducting state in response to both of the signals.

5. The semiconductor device of claim 1, wherein the second control port overlaps a junction between the first and second base regions.

6. The semiconductor device of claim 1, wherein the second control port underlaps a junction between the first and second base regions.

7. A semiconductor device comprising:

a thyristor having first and second base regions coupled to one another and respectively to first and second emitter regions;

a first control port configured and arranged to capacitively couple a first signal to at least the first base region; and

a second control port configured and arranged to capacitively couple a second signal to at least the second base region, the first and second signals having opposite polarities, wherein the thyristor is adapted to switch between a blocking state and a conducting state in response to the first and second signals.

8. The semiconductor device of claim 7, wherein the first and second control ports are adapted to concurrently capacitively couple a signal to each of the first and second base regions.

9. The semiconductor device of claim 7, further comprising a pass device having a well region between two source/drain regions and a gate electrode over the well region, the gate electrode being adapted to effect a conductive channel between the source/drain regions via the well region in response to a voltage being applied thereto, the pass device being electrically coupled in series with the thyristor between one of the source/drain regions of the pass device and one of the emitter regions of the thyristor.

10. The semiconductor device of claim 9, wherein the one source/drain region and the one emitter region that couple the thyristor to the pass device are the same region.

11. The semiconductor device of claim 9, wherein the source/drain region not coupled to one of the emitter regions is part of a bit line, and wherein the one emitter region is part of an interconnect adapted to supply a reference voltage signal to the emitter.

12. The semiconductor device of claim 9, wherein the semiconductor device forms part of a memory cell.

13. The semiconductor device of claim 12, wherein the gate electrode forms part of a first word line, wherein the first control port forms part of a second word line and wherein the second control port forms part of a third word line.

14. The semiconductor device of claim 13, wherein at least one of the second and third word lines includes polysilicon doped to effect a workfunction between the control port and a surface of one of the base regions, the workfunction being adapted to cause the thyristor to switch between the blocking and conducting states in response to a minimum voltage being applied to the at least one of the second and third word lines.

15. The semiconductor device of claim 13, wherein the memory cell forms part of an array of memory cells, wherein at least a portion of the memory cells share at least one of the word lines and wherein some of the memory cells sharing the at least one word line is electrically coupled to a different reference voltage.

16. The semiconductor device of claim 12, wherein the semiconductor device is adapted to perform a write operation in response to both of the control ports capacitively coupling a signal to at least one of the base regions.

17. The semiconductor device of claim 7, wherein the thyristor is adapted to switch from a blocking state to a passing state in response to the first control port capacitively coupling a positive signal to the first base region and the second control port capacitively coupling a negative signal to the second base region.

18. The semiconductor device of claim 7, wherein the thyristor is adapted to switch between a passing state and a blocking state when the power supplied via the first and second signals is about one half of the power that would be required to cause the thyristor to switch between the passing and blocking states, absent the second control port.

19. The semiconductor device of claim 7, wherein the first and second control ports are adapted to independently capacitively couple signals to the first and second base regions, respectively.

20. The semiconductor device of claim 7, wherein the thyristor is a thin capacitively coupled thyristor.

21. The semiconductor device of claim 7, wherein the thyristor is at least partly on an insulator portion of silicon on insulator (SOI) structure.

22. The semiconductor device of claim 7, wherein at least a portion of the thyristor is formed vertically in a semiconductor substrate.

23. The semiconductor device of claim 7, wherein at least one of the first and second control ports comprises doped polysilicon.

24. The semiconductor device of claim 23, wherein the doped polysilicon control port comprises polysilicon doped with boron.

25. The semiconductor device of claim 23, wherein the doped polysilicon control port comprises polysilicon degenerately doped with phosphorous.

26. The semiconductor device of claim 23, wherein the doped polysilicon control port is adapted to inhibit undesired current flow at a region of the semiconductor device immediately adjacent to the control port.

27. The semiconductor device of claim 23, further comprising at least one MOSFET device adapted to operate at a first voltage, wherein the doped polysilicon control port is adapted to switch the thyristor between a blocking state and a conducting state in response to the first voltage being applied to the doped polysilicon control port.

28. The semiconductor device of claim 7, wherein the second control port underlaps a junction between the first and second base region.

29. The semiconductor device of claim 28, wherein the second control port is configured and arranged to capacitively couple the second signal predominantly to the second base region.

30. The semiconductor device of claim 7, wherein the second control port overlaps a junction between the first and second base region and capacitively couples the second signal to the first and second base region.

31. The semiconductor device of claim 7, wherein the second control port has a sidewall that is aligned with a junction between the first and second base region.

32. The semiconductor device of claim 31, wherein the first and second base regions are vertically arranged.

33. The semiconductor device of claim 31, wherein the first and second base regions are laterally arranged.

34. The semiconductor device of claim 7, wherein the first emitter region is in a substrate, further comprising a carrier isolation region in the substrate and configured and arranged for inhibiting excess carriers from migrating from one of the emitter regions to other circuitry in the substrate.

36. The semiconductor device of claim 32, wherein the second source/drain region is coupled to a bit line and wherein the second emitter region is coupled to a reference voltage line.

37. The semiconductor device of claim 36, further comprising a control circuit configured and arranged for controlling the coupling of signals to the pass device and the thyristor.

38. The semiconductor device of claim 37, wherein the control circuit is configured and arranged for inhibiting the second base and the second emitter from becoming forward biased during a write “

Zero”

operation by pulsing a signal at the reference voltage line below zero.

35. A thyristor-based memory cell comprising:

a pass device including a transistor having a well region between first and second source/drain regions and a gate forming part of a first word line; and

a thyristor device comprising;

first and second base regions coupled to one another and respectively to first and second emitter regions, the second emitter region being coupled in series to the first source/drain regions of the pass device; and

a first thyristor control port forming part of a second word line and configured and arranged to capacitively couple a first signal from the second word line to the first base region; and

a second thyristor control port forming part of a third word line and configured and arranged to capacitively couple a second signal from the third word line to the second base region, the second signal being opposite in polarity to the first signal, wherein the thyristor device is adapted to switch between a blocking state and a conducting state in response to the first and second capacitively coupled signals.