Micromechanical memory element

• US 6,625,047 B2
• Filed: 12/31/2001
• Issued: 09/23/2003
• Est. Priority Date: 12/31/2000
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Coleman, Donald J. Jr.
• Primary Examiner(s): PERT, EVAN T
• Application Number:
  US10/036,610
• Publication Number:
  US 20020097136A1
• Time in Patent Office: 631 Days
• Field of Search: 438/128, 438/129, 438/130, 438/131, 438/132, 365/51, 365/52, 365/63, 365/66, 365/129, 365/157, 365/164, 365/166, 257/202, 257/208, 257/211
• US Class Current: 365/51
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: G11C 2213/17 Memory cell being a nanowire transistor
• CPC Class Codes: G11C 23/00 Digital stores characterised by movement of mechanical parts to effect storage, e.g. using balls; Storage elements therefor
• CPC Class Codes: H01H 1/0036 Switches making use of microelectromechanical systems [MEMS] for electromagnetic relays H01H50/005; for electrostatic relays H01H59/0009
• CPC Class Codes: H01H 2001/0042 Bistable switches, i.e. having two stable positions requiring only actuating energy for switching between them, e.g. with snap membrane or by permanent magnet
• CPC Class Codes: H01H 59/0009 making use of micromechanics

Abstract

A micromechanical memory 100 element comprising a deflectable member 102 located between a first member 104 and a second member 106. The first member 104 is biased at a first member voltage, and the second member 106 is biased at a second member voltage. A bias voltage applied to the deflectable member will drive the deflectable member to either the first member 104 or the second member 106. A first contact 108 is positioned on the top, or end, of the first member 104. A second contact 110 is positioned on the top, or end, of the second member 106. These contacts are biased through resistors 112 and 114 with a first and second contact voltage sufficient to hold the deflectable member in place even after removal of the bias voltage applied to the deflectable member. The state of the micromechanical memory element can be determined by sensing the voltage of the deflectable member 102.

Claims

1. A micromechanical memory element comprising:

a pass transistor;

a first member biased at a first member voltage;

a second member biased at a second member voltage;

a deflectable member between said first and second members, said deflectable member receiving an electrical signal from said pass transistor, said deflectable member operable to deflect toward said first member when said electrical signal is a first state, and toward said second member when said electrical signal is a second state;

a first contact positioned to contact said deflectable member when said deflectable member is deflected toward said first member, said first contact providing a first contact voltage operable to hold said deflectable member in contact with said first contact in the absence of a signal from said pass transistor; and

a second contact positioned to contact said deflectable member when said deflectable member is deflected toward said first member, said second contact providing a second contact voltage operable to hold said deflectable member in contact with said second contact in the absence of a signal from said pass transistor.

2. The micromechanical memory element of claim 1, said deflectable member comprising a silicon deflectable member.

3. The micromechanical memory element of claim 1, said deflectable member comprising a metal deflectable member.

4. The micromechanical memory element of claim 1, said micromechanical memory element fabricated on a plane, said deflectable member deflecting parallel to said plane.

5. The micromechanical memory element of claim 1, said micromechanical memory element fabricated on a plane, said deflectable member deflecting perpendicular to said plane.

6. The micromechanical memory element of claim 1, said first member comprising a silicon member.

7. The micromechanical memory element of claim 1, said first member comprising a metal member.

8. The micromechanical memory element of claim 1, said first member comprising a first rigid member.

9. The micromechanical memory element of claim 1, said second member comprising a silicon member.

10. The micromechanical memory element of claim 1, said second member comprising a metal member.

11. The micromechanical memory element of claim 1, said second member comprising a second rigid member.

12. The micromechanical memory element of claim 1, said first contact located on said first member.

13. The micromechanical memory element of claim 1, said first contact located on said first member and electrically isolated from said first member.

14. The micromechanical memory element of claim 1, said second contact located on said second member.

15. The micromechanical memory element of claim 1, said second contact located on said second member and electrically isolated from said second member.

16. The micromechanical memory element of claim 1, said first contact being a resistive contact.

17. The micromechanical memory element of claim 1, said second contact being a resistive contact.

18. The micromechanical memory element of claim 1, said first contact voltage being said second member voltage.

19. The micromechanical memory element of claim 1, said second contact voltage being said first member voltage.

20. The micromechanical memory element of claim 1, further comprising a reset mechanism operable to move said deflectable member out of contact with said first and second contacts.

21. The micromechanical memory element of claim 1, further comprising a reset electrode, a reset voltage applied to said reset electrode operable to move said deflectable member out of contact with said first and second contacts.

22. The micromechanical memory element of claim 1, said deflectable member having a stiffness great enough to break contact with said first contact when said electrical signal is in said second state.

23. The micromechanical memory element of claim 1, said deflectable member having a stiffness great enough to break contact with said second contact when said electrical signal is in said first state.

24. The micromechanical memory element of claim 1, comprising:

a sense amplifier electrically connected to said deflectable member and operable to detect a signal applied to said deflectable member.

25. The micromechanical memory element of claim 1, comprising:

a sense amplifier electrically connected to said deflectable member through said pass transistor, said sense amplifier operable to detect a signal applied to said deflectable member.

26. The micromechanical memory element of claim 1, comprising:

a bitline operable to deliver said electrical signal to said pass transistor.

27. The micromechanical memory element of claim 1, comprising:

a wordline operable to deliver an enable signal to said pass transistor.

28. A micromechanical memory element comprising:

means for deflecting a deflectable member in one of two positions depending on a state of an input signal line;

means for holding said deflectable member in said deflected state; and

means for detecting said deflected state.

29. The micromechanical memory element of claim 28, comprising:

a means for reading the position of said deflectable member.

30. A micromechanical memory element comprising:

a pass transistor;

a first member biased at a first member voltage;

a deflectable member receiving an electrical signal from said pass transistor, said deflectable member operable to deflect toward said first member when said electrical signal is a first state; and

a first contact positioned to contact said deflectable member when said deflectable member is deflected toward said first member, said first contact providing a first contact voltage operable to hold said deflectable member in contact with said first contact in the absence of a signal from said pass transistor.

31. The micromechanical memory element of claim 30, said deflectable member comprising a silicon deflectable member.

32. The micromechanical memory element of claim 30, said deflectable member comprising a metal deflectable member.

33. The micromechanical memory element of claim 30, said micromechanical memory element fabricated on a plane, said deflectable member deflecting parallel to said plane.

34. The micromechanical memory element of claim 30, said micromechanical memory element fabricated on a plane, said deflectable member deflecting perpendicular to said plane.

35. The micromechanical memory element of claim 30, said first member comprising a silicon member.

36. The micromechanical memory element of claim 30, said first member comprising a metal member.

37. The micromechanical memory element of claim 30, said first member comprising a first rigid member.

38. The micromechanical memory element of claim 30, said first contact located on said first member.

39. The micromechanical memory element of claim 30, said first contact located on said first member and electrically isolated from said first member.

40. The micromechanical memory element of claim 30, said first contact being a resistive contact.

41. The micromechanical memory element of claim 30, further comprising a reset mechanism operable to move said deflectable member out of contact with said first contact.

42. The micromechanical memory element of claim 30, further comprising a reset electrode, a reset voltage applied to said reset electrode operable to move said deflectable member out of contact with said first contact.

43. The micromechanical memory element of claim 30, said deflectable member having a stiffness great enough to break contact with said first contact when said electrical signal is in said second state.

44. The micromechanical memory element of claim 30, comprising:

a sense amplifier electrically connected to said deflectable member and operable to detect a signal applied to said deflectable member.

45. The micromechanical memory element of claim 30, comprising:

a sense amplifier electrically connected to said deflectable member through said pass transistor, said sense amplifier operable to detect a signal applied to said deflectable member.

46. The micromechanical memory element of claim 30, comprising:

a bitline operable to deliver said electrical signal to said pass transistor.

47. The micromechanical memory element of claim 30, comprising:

a wordline operable to deliver an enable signal to said pass transistor.

48. A method of forming a micromechanical memory element, the method comprising:

providing a semiconductor substrate;

forming addressing circuitry on said substrate;

forming a first member and a first contact on said substrate, said first member and said first contact electrically connected to said addressing circuitry;

forming a first sacrificial layer on said substrate; and

forming a deflectable member on said first sacrificial layer, said deflectable member electrically connected to said substrate.

49. The method of claim 48, comprising:

forming a second sacrificial layer on said deflectable member;

forming a second member and a second contact on said second sacrificial layer, said second member and said second contact electrically connected to said addressing circuitry; and

removing said first and second sacrificial layers.