Magnetic tunnel junction pressure sensors and methods

• US 20070099031A1
• Filed: 10/28/2005
• Published: 05/03/2007
• Est. Priority Date: 10/28/2005
• Status: Active Grant

• Current Assignee: Everspin Technologies Incorporated
• Original Assignee: Everspin Technologies Incorporated
• Inventors: Chung, Young, Baird, Robert, Engel, Bradley
• Granted Patent: US 7,547,480 B2
• Time in Patent Office: Days
• US Class Current: 428/815
• CPC Class Codes: G01L 19/16 Dials; Mounting of dials
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect
• CPC Class Codes: Y10T 428/1114 having tunnel junction effect
• CPC Class Codes: Y10T 428/1143 with defined structural feature
• CPC Class Codes: Y10T 428/1171 with defined laminate structural detail

Abstract

An integrated circuit device is provided which comprises a substrate, a conductive line configured to experience a pressure, and a magnetic tunnel junction (“MTJ”) core formed between the substrate and the current line. The conductive line is configured to move in response to the pressure, and carries a current which generates a magnetic field. The MTJ core has a resistance value which varies based on the magnetic field. The resistance of the MTJ core therefore varies with respect to changes in the pressure. The MTJ core is configured to produce an electrical output signal which varies as a function of the pressure.

Claims

1. An integrated circuit device, comprising:

a substrate;

a first insulating layer having a magnetic tunnel junction (“

MTJ”

) core formed therein;

a second insulating layer, disposed over the first insulating layer, the second insulating layer having a conductive line disposed therein and defining a cavity therein, wherein the conductive line is configured to produce a magnetic field, and wherein at least a portion of the cavity is disposed between the conductive line and the MTJ core and

wherein a resistance value of the MTJ core varies with changes in the magnetic field experienced by the MTJ core.

2. An integrated circuit device according to claim 1, wherein the second insulating layer flexes in response to pressure applied to the second insulating layer and wherein the resistance value of the MTJ core changes in response to pressure experienced by the second insulating layer.

3. An integrated circuit device according to claim 2, wherein a distance between the conductive line and the MTJ core varies based on the pressure experienced by the second insulating layer, and wherein the resistance value of the MTJ core varies with respect to the distance between the conductive line and the MTJ core.

4. An integrated circuit device according to claim 3, wherein the MTJ core is configured to sense the pressure and generate an electrical output signal responsive to the pressure.

5. An integrated circuit device according to claim 4, wherein the electrical output signal generated by the MTJ core varies based on the resistance value of the MTJ core.

6. An integrated circuit device according to claim 5, wherein the electrical output signal of the MTJ core is used to determine the pressure experienced by the second insulating layer.

7. An integrated circuit device according to claim 6, further comprising:

a pressure sensor conversion circuit configured to associate the electrical output signal produced by the MTJ core with the pressure experienced by the second insulating layer.

8. An integrated circuit device according to claim 1, wherein the substrate is formed from front end layers by a front end fabrication process, wherein the MTJ core is formed from back end layers by a back end fabrication process which occurs after the front end fabrication process.

9. An integrated circuit device, comprising:

a conductive line configured to move in response to change in a pressure experienced by the conductive line;

a magnetic tunnel junction (“

MTJ”

) core having a resistance value which varies as a function of the pressure, and being configured to generate a electrical output signal which varies based on the resistance value of the MTJ core; and

a pressure sensor circuit configured to associate a value of the electrical output signal produced by the MTJ core with a pressure value experienced by the conductive line.

10. A method of producing an integrated circuit, the method comprising:

providing a substrate;

providing a first insulating layer on the substrate, the first insulating layer having a magnetic tunnel junction (“

MTJ”

) core formed therein;

providing a sacrificial layer on the first insulating layer over the MTJ core;

forming a conductive line on the sacrificial layer, wherein the conductive line is configured to produce a magnetic field;

forming a second insulating layer over the conductive line and the sacrificial layer such that the second insulating layer surrounds at least a portion of the sacrificial layer; and

removing the sacrificial layer to define a cavity between the conductive line and the MTJ core, wherein at least a portion of the second insulating layer is configured to flex in response to pressure applied to the second insulating layer.

11. A method according to claim 10, wherein a distance between the conductive line and the MTJ core varies based on the pressure experienced by the second insulating layer, and wherein the magnetic field experienced by the MTJ core changes in response to the pressure.

12. A method according to claim 11, wherein a resistance value of the magnetic tunnel junction core varies with respect to the distance between the conductive line and the MTJ core.

13. A method according to claim 12, wherein the resistance value of the magnetic tunnel junction core varies with changes in the magnetic field experienced by the MTJ core.