Construction and application for non-volatile reprogrammable switches

• US 6,256,225 B1
• Filed: 02/26/1999
• Issued: 07/03/2001
• Est. Priority Date: 02/26/1999
• Status: Expired due to Fees

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Noble, Wendell P., Cloud, Eugene H.
• Primary Examiner(s): Nelms, David
• Assistant Examiner(s): Lam, David
• Application Number:
  US09/261,479
• Time in Patent Office: 858 Days
• Field of Search: 365/185.05, 365/185.14, 365/185.26, 365/185.28, 365/185.33, 365/149, 257/301, 257/303
• US Class Current: 365/185.05
• CPC Class Codes: G11C 16/0441 comprising cells containing multiple floating gate devices, e.g. separate read-and-write FAMOS transistors with connected floating gates
• CPC Class Codes: G11C 16/045 Floating gate memory cells with both P and N channel memory transistors, usually sharing a common floating gate
• CPC Class Codes: H01L 29/40114 the electrodes comprising a conductor-insulator-conductor-insulator-semiconductor structure
• CPC Class Codes: H10B 69/00 Erasable-and-programmable ROM [EPROM] devices not provided for in groups H10B41/00 - H10B63/00, e.g. ultraviolet erasable-and-programmable ROM [UVEPROM] devices

Abstract

The present invention includes a DRAM technology compatible non-volatile, reprogrammable switch formed according to an DRAM optimized process flow. The non-volatile, reprogrammable switch includes a non-volatile memory cell. The non-volatile memory cell includes a first metal oxide semiconductor field effect transistor (MOSFET) formed in a semiconductor substrate. A capacitor is formed in a subsequent layer above the first MOSFET and is separated from the MOSFET by an insulator layer. A vertical electrical via couples a bottom plate of the capacitor through the insulator layer to a gate of first MOSFET. A second MOSFET is formed in the semiconductor substrate. The gate of the first MOSFET also serves as a gate of the second MOSFET. Additional MOSFETs can be combined in a similar fashion with the non-volatile cell to create a new, powerful logic cell that is smaller and more robust than conventional circuit solutions.

The present invention includes applications such as a very size efficient address decode tree, data routing device, or other applications such as used in DRAM redundancy schemes. Methods for forming and using the present invention are also included. The need for intervening sense amps normally required to read the status of a non-volatile memory cell (e.g. an EEPROM cell) and communicate this to additional logic that would then in turn control the status of one or more switches is eliminated. Thus, the requirements of low power densely packed integrated circuits is realized for smaller, portable microprocessor devices.

Claims

1. A non-volatile, reprogrammable switch, comprising:

a non-volatile memory cell, wherein the non-volatile memory cell includes;

a first metal oxide semiconductor field effect transistor (MOSFET) formed in a semiconductor substrate;

a capacitor formed in a subsequent layer above the first MOSFET and separated from the MOSFET by an insulator layer; and

a vertical electrical via coupling a bottom plate of the capacitor through the insulator layer to a gate of first MOSFET; and

a second MOSFET formed in the semiconductor substrate, wherein the gate of the first MOSFET also serves as a gate of the second MOSFET.

2. The non-volatile, reprogrammable switch of claim 1, wherein the capacitor includes a stacked capacitor formed according to a dynamic random access memory (DRAM) process flow.

3. The non-volatile, reprogrammable switch of claim 1, wherein the first MOSFET includes an n-channel metal oxide semiconductor (NMOS) transistor.

4. The non-volatile, reprogrammable switch of claim 1, wherein the second MOSFET includes a p-channel metal oxide semiconductor (PMOS) transistor.

5. The non-volatile, reprogrammable switch of claim 1, wherein the second MOSFET includes a channel region separated from the gate by a gate oxide, and wherein the channel region couples a first diffused region and a second diffused region.

6. The non-volatile, reprogrammable switch of claim 1, wherein the first MOSFET includes a channel region separated from the gate by a gate oxide, and wherein the channel region couples a first diffused region to a second diffused region.

7. The non-volatile, reprogrammable switch of claim 1, wherein the capacitor includes a top plate which serves as a control gate for the non-volatile memory cell.

8. A non-volatile, reprogrammable switch, comprising:

a non-volatile memory cell, wherein the non-volatile memory cell includes;

a first metal oxide semiconductor field effect transistor (MOSFET) formed in a semiconductor substrate;

a stacked capacitor formed according to a dynamic random access memory (DRAM) process in a subsequent layer above the MOSFET and separated from the MOSFET by an insulator layer; and

an electrical contact coupling a bottom plate of the stacked capacitor through the insulator layer to a gate of first MOSFET; and

a second MOSFET formed in the semiconductor substrate, wherein the gate of the first MOSFET also serves as a gate of the second MOSFET.

9. The non-volatile, reprogrammable switch of claim 8, wherein the first MOSFET serves as a programming element and the second MOSFET serves as a switching element.

10. The non-volatile, reprogrammable switch of claim 9, wherein the stacked capacitor includes a top plate which serves as a control gate for the programming element.

11. The non-volatile, reprogrammable switch of claim 10, wherein the bottom plate of the stacked capacitor is cup shaped having interior walls and exterior walls and is separated by a capacitor dielectric from the top plate.

12. The non-volatile, reprogrammable switch of claim 11, wherein the capacitor dielectric is conformal to the bottom plate, and wherein the top plate is conformal to the capacitor dielectric, a portion of the top plate being located within the interior walls of the bottom plate.

13. The non-volatile, reprogrammable switch of claim 8, wherein the electrical contact includes a polysilicon plug.

14. The non-volatile, reprogrammable switch of claim 8, wherein the non-volatile memory cell includes a FLASH memory cell.

15. A non-volatile, reprogrammable switch, comprising:

a non-volatile memory cell, wherein the non-volatile memory cell includes;

a first metal oxide semiconductor field effect transistor (MOSFET) formed in a semiconductor substrate;

a stacked capacitor formed in a subsequent layer above the first MOSFET and separated from the MOSFET by an insulator layer; and

a vertical electrical via coupling a bottom plate of the capacitor through the insulator layer to a gate of first MOSFET;

a second MOSFET formed in the semiconductor substrate, wherein the gate of the first MOSFET also serves as a gate of the second MOSFET; and

a third MOSFET formed in the semiconductor substrate, wherein the gate of the first and second MOSFET also serves as a gate of the third MOSFET.

16. The non-volatile, reprogrammable switch of claim 15, wherein the second MOSFET includes an n-channel metal oxide semiconductor (NMOS) transistor, and wherein the third MOSFET includes a p-channel metal oxide semiconductor (PMOS) transistor.

17. The non-volatile, reprogrammable switch of claim 15, wherein the second MOSFET includes a channel region separated from the gate by a gate oxide, and wherein the channel region couples a first diffused region and a second diffused region.

18. The non-volatile, reprogrammable switch of claim 17, wherein an input node is coupled to the first diffused region and an output node is coupled to the second diffused region.

19. The non-volatile, reprogrammable switch of claim 18, wherein the non-volatile memory cell serves as a programming element and the second MOSFET serves as a switching element, wherein the second MOSFET couples the input node to the output node when the gate of the second MOSFET is in a first programmed state.

20. The non-volatile, reprogrammable switch of claim 15, wherein the third MOSFET includes a channel region separated from the gate by a gate oxide, and wherein the channel region couples a first diffused region and a second diffused region.

21. The non-volatile, reprogrammable switch of claim 20, wherein an input node is coupled to the first diffused region and an output node is coupled to the second diffused region.

22. The non-volatile, reprogrammable switch of claim 21, wherein the non-volatile memory cell serves as a programming element and the third MOSFET serves as a switching element, wherein the third MOSFET couples the input node to the output node when the gate of the third MOSFET is in a second programmed state.

23. A data decoding device, comprising:

a number of non-volatile, reprogrammable switches, wherein each non-volatile, reprogrammable switch includes;

a non-volatile memory cell, wherein the non-volatile memory cell includes;

a first metal oxide semiconductor field effect transistor (MOSFET) formed in a semiconductor substrate;

a capacitor formed in a subsequent layer above the first MOSFET and separated from the MOSFET by an insulator layer; and

a vertical electrical via coupling a bottom plate of the capacitor through the insulator layer to a gate of first MOSFET; and

a second MOSFET formed in the semiconductor substrate, wherein the gate of the first MOSFET also serves as a gate of the second MOSFET;

a number of programming control lines coupled to the non-volatile memory cells in the number of non-volatile, reprogrammable switches;

a number of input bit lines coupled to an input node for the second MOSFET in the number of non-volatile, reprogrammable switches; and

a number of output bit lines coupled to an output node for the second MOSFET in the number of non-volatile, reprogrammable switches.

24. The data decoding device of claim 23, wherein the capacitor includes a stacked capacitor formed according to a dynamic random access memory (DRAM) process flow.

25. The data decoding device of claim 23, wherein the first MOSFET includes an n-channel metal oxide semiconductor (NMOS) transistor.

26. The data decoding device of claim 23, wherein the second MOSFET includes a p-channel metal oxide semiconductor (PMOS) transistor.

27. The data decoding device of claim 23, wherein the second MOSFET is a switching element and includes a first diffused region coupled to a second diffused region, wherein the first diffused region serves as the input node for the second MOSFET and the second diffused region serves as the output node for the second MOSFET.

28. The data decoding device of claim 23, wherein a first one of the number of control lines couples to a first diffused region for the first MOSFET, a second one of the number of control lines couples to a second diffused region for the first MOSFET, and wherein a third one of the number of control lines couples to a top plate of the capacitor.

29. The data decoding device of claim 28, wherein the non-volatile memory cell is a programming element, wherein the bottom plate of the capacitor is a floating gate.

30. The data decoding device of claim 29, wherein the second MOSFET conducts an applied signal from the input node to the output node when the floating gate is in a first programmed state, and wherein the second MOSFET conducts less of the applied signal from the input node to the output node when the floating gate is in a second programmed state.

31. A data routing device, comprising:

a number of non-volatile, reprogrammable switches, wherein each non-volatile, reprogrammable switch includes;

a non-volatile memory cell, wherein the non-volatile memory cell includes;

a first metal oxide semiconductor field effect transistor (MOSFET) formed in a semiconductor substrate;

a capacitor; and

a vertical electrical via coupling a bottom plate of the capacitor through an insulator layer to a gate of first MOSFET;

a second MOSFET formed in the semiconductor substrate, wherein the gate of the first MOSFET also serves as a gate of the second MOSFET; and

a third MOSFET formed in the semiconductor substrate, wherein the gate of the first and second MOSFET also serves as a gate of the third MOSFET;

a number of programming control lines coupled to the non-volatile memory cells in the number of non-volatile, reprogrammable switches;

a number of input bit lines coupled to an input node for the second MOSFET and to an input node for the third MOSFET in the number of non-volatile, reprogrammable switches; and

a number of output bit lines coupled to an output node for the second MOSFET and to an output node for the third MOSFET in the number of non-volatile, reprogrammable switches.

32. The data routing device of claim 31, wherein the number of output bit lines further couple the output node for the second MOSFET and the output node for the third MOSFET to the input node for the second MOSFET and the input node for the third MOSFET in the other ones of the number of non-volatile, reprogrammable switches.

33. The data routing device of claim 32, wherein the second MOSFET is turned “

on” and

the third MOSFET is turned “

off”

when the floating gate is in a first programmed state, and wherein the second MOSFET is turned “

off” and

the third MOSFET is turned “

on”

when the floating gate is in a second programmed state.

34. The data routing device of claim 31, wherein the second MOSFET is an channel metal oxide semiconductor (NMOS) transistor, and the third MOSFET is a p-channel metal oxide semiconductor (PMOS) transistor.

35. The data routing device of claim 34, wherein the non-volatile memory cell is a programming element, and wherein the bottom plate of the capacitor is a floating gate.

36. The data routing device of claim 31, wherein a first one of the number of control lines couples to a first diffused region for the first MOSFET, a second one of the number of control lines couples to a second diffused region for the first MOSFET, and wherein a third one of the number of control lines couples to a top plate of the capacitor.

37. The data routing device of claim 31, wherein the number of non-volatile reprogrammable switches are formed on a dynamic random access memory (DRAM) chip according to a DRAM technology process flow.

38. An electronic system, comprising:

a processor;

a dynamic random access memory (DRAM) chip; and

a system bus coupling the processor to the DRAM chip, wherein the DRAM chip includes an array of non-volatile, reprogrammable switches, wherein each non-volatile, reprogrammable switch includes;

a non-volatile memory cell, wherein the non-volatile memory cell includes;

a first metal oxide semiconductor field effect transistor (MOSFET) formed in a semiconductor substrate;

a stacked capacitor; and

a vertical electrical via coupling a bottom plate of the stacked capacitor through an insulator layer to a gate of first MOSFET; and

a second MOSFET formed in the semiconductor substrate, wherein the gate of the first MOSFET also serves as a gate of the second MOSFET.

39. The electronic system of claim 38, wherein the stacked capacitor includes a top plate which serves as a control gate for the non-volatile memory cell.

40. The electronic system of claim 39, wherein the bottom plate of the stacked capacitor is cup shaped having interior walls and exterior walls and is separated by a capacitor dielectric from the top plate.

41. The electronic system of claim 40, wherein the capacitor dielectric is conformal to the bottom plate, and wherein the top plate is conformal to the capacitor dielectric, a portion of the top plate being located within the interior walls of the bottom plate.

42. The electronic system of claim 38, wherein the vertical electrical via includes a polysilicon plug.

43. The electronic system of claim 38, wherein the non-volatile memory cell includes a FLASH memory cell.

44. The electronic system of claim 38, wherein the stacked capacitor includes a stacked capacitor formed according to a dynamic random access memory (DRAM) process flow.

45. The electronic system of claim 38, wherein first MOSFET includes an n-channel metal oxide semiconductor (NMOS) transistor.

46. The electronic system of claim 38, wherein the second MOSFET includes a p-channel metal oxide semiconductor (PMOS) transistor.

47. The electronic system of claim 38, wherein the second MOSFET is a switching element, wherein the switching element is turned “

on”

when the non-volatile memory cell is in a first programmed state, and wherein the switching element is turned “

off”

when the non-volatile memory cell is in a second programmed state.

48. A method for operating a non-volatile, reprogrammable switch, comprising:

controlling a charge on a gate of a first metal oxide semiconductor field effect transistor (MOSFET), wherein controlling the charge on the gate of the first MOSFET includes controlling a charge on a bottom plate of a stacked capacitor, wherein the bottom plate of the stacked capacitor is coupled to the gate of the first MOSFET through an insulator layer, and wherein the gate of the first MOSFET is shared as a gate for a second MOSFET; and

applying a first signal to a first diffused region for the second MOSFET; and

outputting a second signal from a second diffused region for the second MOSFET to another circuit component on an integrated circuit.

49. The method of claim 48, wherein controlling a charge on a gate the first MOSFET includes placing a charge on the gate of the first MOSFET using Fowler Nordheim tunneling.

50. The method of claim 48, wherein controlling a charge on the gate of the first MOSFET includes removing a charge from the gate of the first MOSFET and the second MOSFET to a source region for the first MOSFET.

51. A method for operating a switching element, comprising:

sharing a gate between a first, a second, and a third MOSFET;

placing a charge on the gate, wherein placing a charge on the gate includes applying a control voltage to a top plate of a stacked capacitor located above the first MOSFET, wherein a bottom plate of the stacked capacitor is coupled by a vertical electrical via through an insulator to the gate; and

reading a current conducted through the second MOSFET.

52. The method of claim 51, wherein placing a charge on the gate includes using channel hot electron (CHE) injection to excite electrons from a channel region of the first MOSFET to the gate.

53. The method of claim 51, wherein placing a charge on the gate includes using Fowler Nordheim tunneling to excite electrons from a source region of the first MOSFET to the gate.

54. The method of claim 51, wherein the method further includes reading a current conducted through the third MOSFET.

55. A method for operating a switching element, comprising:

sharing a gate between a non-volatile memory cell and a first, and a second, MOSFET, wherein the gate is a floating gate for the non-volatile memory cell;

programming the non-volatile memory cell in either a first or a second programmed state; and

reading a current conducted through the first MOSFET.

56. The method of claim 55, wherein the method further includes reading the second MOSFET.

57. The method of claim 55, wherein programming the non-volatile memory cell in either a first or a second programmed state includes turning “

on”

the first MOSFET and turning “

off”

the second MOSFET when the non-volatile memory cell in a first programmed state.