Integrated cantilever switch

Patent metadata

Field	Value
Publication number	US-2016293371-A1
Application number	US-201514675359-A
Country	US
Kind code	A1
Filing date	Mar 31, 2015
Priority date	Mar 31, 2015
Publication date	Oct 6, 2016
Grant date	—

Abstract

An integrated transistor in the form of a nanoscale electromechanical switch eliminates CMOS current leakage and increases switching speed. The nanoscale electromechanical switch features a semiconducting cantilever that extends from a portion of the substrate into a cavity. The cantilever flexes in response to a voltage applied to the transistor gate thus forming a conducting channel underneath the gate. When the device is off, the cantilever returns to its resting position. Such motion of the cantilever breaks the circuit, restoring a void underneath the gate that blocks current flow, thus solving the problem of leakage. Fabrication of the nano-electromechanical switch is compatible with existing CMOS transistor fabrication processes. By doping the cantilever and using a back bias and a metallic cantilever tip, sensitivity of the switch can be further improved. A footprint of the nano-electromechanical switch can be as small as 0.1×0.1 μm 2 .

First claim

1 . An apparatus, comprising:
a silicon substrate; a layered stack overlying the silicon substrate, the layered stack including an epitaxial semiconductor layer; a cavity positioned within the layered stack; a flexible member extending from the epitaxial semiconductor layer of the layered stack into the cavity; and a gate overlying the flexible member, the gate configured to control motion of the flexible member via an electric signal.

2 . The apparatus of claim 1 wherein the gate is configured to control the motion by one or more of a capacitive mechanism, an electrostatic mechanism, or induction.

3 . The apparatus of claim 1 wherein the cavity extends underneath a portion of the gate.

4 . The apparatus of claim 1 wherein the flexible member is a cantilever arm, and the gate is configured to deflect the cantilever arm.

5 . The apparatus of claim 4 wherein the cantilever arm has an aspect ratio greater than 4.0.

6 . The apparatus of claim 4 wherein the cantilever arm is conductive and, when deflected, makes contact with a current-carrying portion of the layered stack, thus closing a switch.

7 . The apparatus of claim 6 wherein the gate is a transistor gate and closing the switch permits current to flow between source and drain terminals of a transistor.

8 . A switch, comprising:
a silicon substrate; a gate electrode overlying the silicon substrate, the gate electrode configured to receive a voltage applied to activate the switch; and a flexible member having a metal tip, the flexible member disposed within a cavity between the silicon substrate and the gate electrode, the metal tip configured to deflect in response to the applied voltage, so as to close the switch.

9 . The switch of claim 8 , further comprising a source region and a drain region formed on the silicon substrate, wherein the switch is a type of transistor.

10 . An integrated circuit that includes the transistor of claim 9 .

11 . The switch of claim 8 , further comprising a buried oxide layer within the silicon substrate and a backside electrical contact to the silicon substrate.

12 . The switch of claim 8 , further comprising a doped epitaxial semiconductor adjacent to the gate electrode, the doped epitaxial semiconductor configured to make contact with the flexible member when a voltage is applied to the gate electrode.

13 . (canceled)

14 . The switch of claim 8 , having a footprint within a range of 0.1×0.1 μm 2 -100×100 μm 2 .

15 .- 23 . (canceled)

24 . A device, comprising:
a silicon substrate; a layered stack on the silicon substrate, the layered stack including
first and second epitaxial semiconducting materials in an alternating arrangement; and
a moveable member having an end that extends from the second epitaxial semiconducting material into a cavity;
a transistor gate structure overlying the moveable member; a raised source region spaced apart from the transistor gate structure by an insulating material; and a raised drain region spaced apart from the transistor gate structure by the insulating material.

25 . The device of claim 24 wherein the raised source and drain regions are faceted.

26 . The device of claim 24 wherein the moveable member is a cantilever arm.

27 . The device of claim 24 wherein the insulating material is a spin-on glass material.

28 . The device of claim 24 wherein the transistor gate structure includes a metal gate, a high-k gate dielectric, and insulating sidewall spacers.

29 . The device of claim 24 wherein the epitaxial semiconducting materials include one or more of silicon and silicon germanium.

30 . The device of claim 24 wherein the silicon substrate is a silicon-on-insulator substrate that includes a buried oxide layer.

31 . The device of claim 24 , further comprising a metal tip on the end of the moveable member.

Assignees

• St Microelectronics Inc

Inventors

• Liu Qing
• Zhang John H

Classifications

• H10P50/644

  Anisotropic liquid etching (H10P50/61 takes precedence) · CPC title

• H10P14/3411

  Silicon, silicon germanium or germanium · CPC title

• H01H49/00

  Apparatus or processes specially adapted to the manufacture of relays or parts thereof · CPC title

• H01H50/005

  using micromechanics · CPC title

• H01H59/0009 Primary

  making use of micromechanics · CPC title