Thyristor-based device over substrate surface

• US 6,653,174 B1
• Filed: 12/17/2001
• Issued: 11/25/2003
• Est. Priority Date: 06/05/1998
• 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): Niebling, John F.
• Assistant Examiner(s): Roman, Angel
• Application Number:
  US10/023,052
• Time in Patent Office: 708 Days
• Field of Search: 438/133, 438/135, 257/107, 257/133
• US Class Current: 438/133
• 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 27/0617 comprising components of the field-effect type H01L27/0251 takes precedence
• CPC Class Codes: H01L 27/0688 Integrated circuits having a three-dimensional layout
• CPC Class Codes: H01L 27/1027 Thyristors
• CPC Class Codes: H01L 29/41716 Cathode or anode electrodes for thyristors
• 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 29/749 with turn-on by field effect
• CPC Class Codes: H01L 29/87 Thyristor diodes, e.g. Shockley diodes, break-over diodes
• CPC Class Codes: H10B 10/00 Static random access memory [SRAM] devices
• CPC Class Codes: H10B 10/12 comprising a MOSFET load element
• CPC Class Codes: H10B 12/10 DRAM devices comprising bipolar components

Abstract

A semiconductor device having a thyristor is manufactured in a manner that reduces or eliminates manufacturing difficulties commonly experienced in the formation of such devices. According to an example embodiment of the present invention, a thyristor is formed having some or all of the body of the thyristor extending above a substrate surface of a semiconductor device. The semiconductor device includes at least one transistor having source/drain regions formed in the substrate prior to the formation of the thyristor. One or more layers of material are deposited on the substrate surface and used to form a portion of a body of the thyristor that includes anode and cathode end portions. Each end portion is formed having a base region and an emitter region, and at least one of the end portions includes a portion that is in the substrate and electrically coupled to the transistor. A control port is formed capacitively coupled to at least one of the base regions.

Claims

1. A method for forming a thyristor-based device having a thyristor structure with two base portions and a junction therebetween, the method comprising:

forming a semiconductor substrate having an upper surface;

forming a transistor having a gate over the upper surface and source/drain regions in the substrate below the upper surface;

forming a thyristor with one of the source/drain regions as another portion of the thyristor and with a control port capacitively-coupled to one of the base portions and aligned with the junction.

2. The method of claim 1, wherein forming a thyristor includes using the source/drain regions as an emitter of the thyristor.

3. The method of claim 2, wherein forming the transistor includes doping the source/drain region to be used in the thyristor-based cell to be p+doped.

4. The method of claim 1, wherein forming a thyristor includes using one of the source/drain regions as a cathode of the thyristor.

5. The method of claim 4, wherein forming the transistor includes doping the source/drain region to be used in the thyristor to be n+doped.

6. The method of claim 1, wherein forming a thyristor includes forming a memory cell.

7. The method of claim 1, wherein forming a thyristor includes forming a latch.

8. The method of claim 1, further comprising coupling the thyristor to additional circuitry in the semiconductor substrate.

9. The method of claim 8, wherein coupling the thyristor to additional circuitry includes forming a logic device having a power thyristor.

10. The method of claim 9, wherein forming a logic device includes forming an output driver.

11. The method of claim 9, wherein forming a logic device includes forming a power management device.

12. The method of claim 8, wherein forming a vertical thyristor includes forming an electrostatic discharge circuit adapted to latch and shunt power from the coupled circuitry.

13. The method of claim 1, wherein forming a transistor having a gate includes forming a MOSPET device.

14. The method of claim 1, wherein forming the thyristor includes forming the thyristor using a single deposition process and subsequently implanting the deposited material.

15. The method of claim 1, wherein forming a thyristor includes forming the other portion of the thyristor extending over the upper surface.

16. The method of claim 1, wherein forming the thyristor includes selfaliining one of the base portions to the control port.

20. The method of claim 1, wherein forming the thyristor includes depositing multiple films.

21. The method of claim 1, wherein forming the thyristor-based device includes using the gate of the transistor as a back gate for the thyristor.

22. The method of claim 1, wherein forming the thyristor includes forming a sidewall gate for the thyristor.

23. The method of claim 1, wherein forming the thyristor includes forming one of the base portions having two vertical regions and forming a gate located laterally between the two vertical regions.

24. The method of claim 1, wherein forming the thyristor includes forming the control port self-aligned to one of the base portions of the thyristor structure.

25. The method of claim 1, further comprising frowning a dielectric over the transistor gate, wherein forming the thyristor comprises forming the control port for the thyristor separated from the transistor gate by the dielectric, the dielectric being adapted to reduce parasitic capacitance between the thyristor gate and the transistor gate.

26. The method of claim 25, wherein forming a dielectric over the transistor gate includes forming a nitride etch stop and using the etch stop to form an emitter portion of the thyristor coupled to a source/drain region of the transistor.

27. The method of claim 26, wherein forming a thyristor includes forming one of the base portions of the thyristor extending over the emitter portion and laterally over the nitride etch stop.

28. The method of claim 1, wherein forming a thyristor includes forming amorphous polysilicon, recrystallizing the amorphous polysilicon and forming at least a portion of the thyristor using the recrystallized amorphous polysilicon.

29. The method of claim 1, further comprising forming a hard mask over the transistor gate, the hard mask being adapted to electrically insulate the transistor gate from the thyristor.

30. The method of claim 1, further comprising depositing an oxide over the transistor gate and forming an etch stop over the oxide, prior to forming the thyristor, the etch stop being adapted to reduce capacitive coupling between the control port and the transistor gate.

31. The method of claim 1, wherein forming a thyristor includes forming a local interconnect as part of the thyristor structure and to electrically couple the thyristor to another portion of the semiconductor device.

32. The method of claim 1, wherein forming the thyristor comprises:

forming the control port over the substrate;

forming an oxide over the substrate, the transistor and the control port;

removing a portion of the oxide adjacent the thyristor control port and forming an opening having a sidewall;

etching a portion of the sidewall adjacent the control port and depositing gate oxide in the etched portion; and

forming at least one base section of the thyristor in the opening that is capacitively coupled to the control port via the oxide.

33. The method of claim 1, further comprising frowning a plurality of the thyristor-based devices, the plurality of thyristor-based devices forming a memory device.

34. The method of claim 1, wherein forming the thyristor includes forming a thyristor having a gate that is adapted to capacitively couple a signal to the thyristor to control current passing through the thyristor independently from any MOS inversion channel formation against a portion of the thyristor to which the gate is capacitively coupled.

17. A method for forming a thyristor-based device having a thyristor structure, the method comprising:

forming a semiconductor substrate having an upper surface;

forming a transistor having a gate over the upper surface and source/drain regions in the substrate below the upper surface; and

forming a thyristor by depositing a dielectric over the formed transistor, creating an opening in the dielectric, and forming the thyristor-based device in the etched opening with one of the source/drain regions as a portion of the thyristor and extending over the upper surface.

18. The method of claim 17, further comprising etching the dielectric and exposing the formed transistor and the thyristor.

19. The method of claim 18, further comprising:

forming a gate dielectric on the thyristor; and

forming a control port on the gate dielectric.

35. A method for forming a thin-capacitively-coupled thyristor-based memory device having a thyristor structure, the method comprising:

forming a semiconductor substrate having an upper surface;

forming a transistor having a gate over the upper surface and source/drain regions in the substrate below the upper surface;

after forming the transistor, depositing an oxide layer over the substrate and the transistor;

removing a portion of the oxide over a first one of the source/drain regions and forming an opening, the source/drain region being used as one of the regions of the thyristor;

forming amorphous polysilicon in the opening;

recrystallizing the amorphous polysilicon;

implanting the recrystallized polysilicon and forming a thyristor P base, N base and emitter region in the opening;

exposing a sidewall of the polysilicon;

forming a gate dielectric on the sidewall and adjacent one of the thyristor base portions;

depositing polysilicon on the gate dielectric and forming a thin capacitivcly coupled gate that is capacitively coupled to one of the thyristor base portions;

depositing an oxide material over the substrate, the transistor, the thin capacitively coupled gate and the thyristor portions;

etching a contact opening through the oxide material and to the emitter region formed in the opening;

forming a local interconnect electrically coupled to the exposed emitter region; and

forming an electrical contact to a second one of the source/drain regions.

36. A method for forming a thyristor-based device having a thyristor structure with two base portions and a junction therebetween, the method comprising:

forming a semiconductor substrate having an upper surface;

forming a transistor having a gate over the upper surface and source/drain regions in the substrate below the upper surface; and

forming a thyristor with a control port capacitively-coupled to one of the base portions and aligned with the junction.