IP Library › Granted Patent US 9,201,124
Granted Patent B2
US 9,201,124 · App. 13/182,510 · Granted Dec 1, 2015

Die-sized atomic magnetometer and method of forming the magnetometer

Inventors: Philipp Lindorfer (San Jose, CA); Peter J. Hopper (San Jose, CA); William French (San Jose, CA); Paul Mawson (Los Gatos, CA); Steven Hunt (San Jose, CA); Roozbeh Parsa (San Jose, CA)
Assignee: NATIONAL SEMICONDUCTOR CORPORATION
G01R33/032G01J1/4228G01J1/44G01J5/20H01S5/0261H01S5/026H01S5/183
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Quick Facts
Patent No.
US 9,201,124
App. No.
13/182,510
Granted
Dec 1, 2015
Kind
B2
Abstract

The cost and size of an atomic magnetometer are reduced by attaching together a first die which integrates together a vapor cell, top and side photo detectors, and processing electronics, a second die which integrates together an optics package and a heater for the vapor cell, and a third die which integrates together a VCSEL, a heater for the VCSEL, and control electronics.

Claims (56)

1. A magnetometer comprising:

a first die having a top surface, a bottom surface, and a first die cavity that extends into the first die from the bottom surface of the first die, the first die cavity having a top surface and a side wall surface, the top surface of the first die cavity lying below and spaced apart from the top surface of the first die; and

a second die having a top surface, a bottom surface, and a second die cavity that extends into the second die from the bottom surface of the second die, the second die cavity having a top surface and a side wall surface, the top surface of the second die cavity lying below and spaced apart from the top surface of the second die, the top surface of the second die touching the bottom surface of the first die to close the first die cavity and form a hermetically sealed cell:

wherein the first die includes a first semiconductor structure having a top surface, a bottom surface, and a first semiconductor cavity that extends into the first semiconductor structure from the bottom surface of the first semiconductor structure, the first semiconductor cavity having a top surface and a side wall surface, the top surface of the first semiconductor cavity lying below and spaced apart from the top surface of the first semiconductor structure; and

wherein the first semiconductor structure includes an upper photo detector that lies vertically between the top surface of the first semiconductor structure and the top surface of the first semiconductor cavity, the first photo detector having a first well of a first conductivity type and a first region of a second conductivity type that touches the first well.

2. The magnetometer of claim 1 and further comprising a gas contained within the hermetically sealed cell, the gas including alkali atoms and buffer atoms.

3. The magnetometer of claim 1 wherein the second die includes an optics package attached to the top surface of the second die cavity, the optics package including a circular polarizer.

4. The magnetometer of claim 3 wherein the second die includes a second semiconductor structure having a top surface, a bottom surface, and a second semiconductor cavity that extends into the second semiconductor structure from the bottom surface of the second semiconductor structure, the second semiconductor structure further including a coil that touches the second semiconductor structure.

5. The magnetometer of claim 1 and further comprising:

a third die having a top surface, a bottom surface, and a third die cavity that extends into the third die from the top surface of the third die, the top surface of the third die being attached to the bottom surface of the second die; and

a laser attached to a bottom surface of the third die cavity.

6. The magnetometer of claim 1 wherein the first semiconductor structure further includes a side wall photo detector that lies laterally adjacent to the side wall surface of the first semiconductor cavity, the side wall photo detector having a second well of the first conductivity type and a second region of the second conductivity type that touches the second well.

7. The magnetometer of claim 6 wherein the first semiconductor structure further includes:

a first conductive structure that extends from the top surface of the first semiconductor structure down into the first semiconductor structure to make an electrical connection with the first well;

a second conductive structure that extends from the top surface of the first semiconductor structure down into the first semiconductor structure to make an electrical connection with the second well;

a third conductive structure that extends from the top surface of the first semiconductor structure down into the first semiconductor structure to make an electrical connection with the first region;

a fourth conductive structure that extends from the top surface of the first semiconductor structure down into the first semiconductor structure to make an electrical connection with the second region; and

an electronic circuit that touches the top surface of the first semiconductor structure.

8. The magnetometer of claim 7 wherein the first die further includes an interconnect structure that touches the top surface of the first semiconductor structure, the interconnect structure electrically connecting the electronic circuit to the first, second, third, and fourth conductive structures and to a number of external electrical connections.

9. The magnetometer of claim 8 wherein the first die further includes a mirror that touches a top surface of the interconnect structure.

10. The magnetometer of claim 9 wherein the first die further includes an RF coil structure that touches a top surface of the interconnect structure, the RF coil structure having a number of spaced apart coils that lie in a common plane.

11. A magnetometer comprising:

a first die having a top surface, a bottom surface, and a first die

cavity that extends into the first die from the bottom surface of the first die, the first die cavity having a top surface and a side wall surface, the top surface of the first die cavity lying below and spaced apart from the top surface of the first die; and

a second die having a top surface, a bottom surface, and a second die cavity that extends into the second die from the bottom surface of the second die, the second die cavity having a top surface and a side wall surface, the top surface of the second die cavity lying below and spaced apart from the top surface of the second die, the top surface of the second die touching the bottom surface of the first die to close the first die cavity and form a hermetically sealed cell, wherein the first die includes:

a first semiconductor structure having a top surface, a bottom surface, and a first semiconductor cavity that extends into the first semiconductor structure from the bottom surface of the first semiconductor structure, the first semiconductor cavity having a top surface and a side wall surface, the top surface of the first semiconductor cavity lying below and spaced apart from the top surface of the first semiconductor structure; and

a heat spreader that touches the bottom surface of the first semiconductor structure and the top surface and the side wall surface of the first semiconductor cavity to line the first semiconductor cavity, the heat spreader being thermally conductive.

12. The magnetometer of claim 11 wherein the first semiconductor structure includes:

an upper photo detector that lies vertically between the top surface of the first semiconductor structure and the top surface of the first semiconductor cavity, the first photo detector having a first well of a first conductivity type and a first region of a second conductivity type that touches the first well; and

a side wall photo detector that lies laterally adjacent to the side wall surface of the first semiconductor cavity, the side wall photo detector having a second well of the first conductivity type and a second region of the second conductivity type that touches the second well.

13. The magnetometer of claim 12 wherein the first semiconductor structure further includes:

a first conductive structure that extends from the top surface of the first semiconductor structure down into the first semiconductor structure to make an electrical connection with the first well;

a second conductive structure that extends from the top surface of the first semiconductor structure down into the first semiconductor structure to make an electrical connection with the second well;

a third conductive structure that extends from the top surface of the first semiconductor structure down into the first semiconductor structure to make an electrical connection with the first region;

a fourth conductive structure that extends from the top surface of the first semiconductor structure down into the first semiconductor structure to make an electrical connection with the second region; and

an electronic circuit that touches the top surface of the first semiconductor structure.

14. The magnetometer of claim 13 wherein the first die further includes an interconnect structure that touches the top surface of the first semiconductor structure, the interconnect structure electrically connecting the electronic circuit to the first, second, third, and fourth conductive structures and to a number of external electrical connections.

15. The magnetometer of claim 14 wherein the first die further includes a mirror that touches a top surface of the interconnect structure.

16. The magnetometer of claim 14 wherein the first die further includes an RF coil structure that touches a top surface of the interconnect structure, the RF coil structure having a number of spaced apart coils that lie in a common plane.

17. The magnetometer of claim 11 wherein the heat spreader include a diamond layer.

18. A magnetometer comprising:

a first die having a top surface, a bottom surface, and a silicon-on-insulator (SOI) structure, the SOI structure having a silicon bulk region, an insulator, and a silicon active region, the first die further having a first die cavity that extends through the silicon bulk region and insulator to expose a bottom surface of the silicon active region, the first die cavity having a top surface and a side wall surface, the top surface of the first die cavity lying below and spaced apart from the top surface of the first die; and

a second die having a top surface, a bottom surface, and a second die cavity that extends into the second die from the bottom surface of the second die, the second die cavity having a top surface and a side wall surface, the top surface of the second die cavity lying below and spaced apart from the top surface of the second die, the top surface of the second die touching the bottom surface of the first die to close the first die cavity and form a hermetically sealed cell, wherein the second die includes a semiconductor structure.

19. The magnetometer of claim 18 , further comprising a gas contained within the hermetically sealed cell, the gas including alkali atoms and buffer atoms.

20. The magnetometer of claim 18 wherein the first die includes a heat spreader that touches a bottom surface of the SOI structure and the top surface and the side wall surface of the first die cavity to line the first die cavity, the heat spreader being thermally conductive.

21. The magnetometer of claim 18 wherein the SOI structure includes:

an upper photo detector that lies vertically between a top surface of the SOI structure and the top surface of the first die cavity, the first photo detector having a first well of a first conductivity type and a first region of a second conductivity type that touches the first well; and

a side wall photo detector that lies laterally adjacent to the side wall surface of the first die cavity, the side wall photo detector having a second well of the first conductivity type and a second region of the second conductivity type that touches the second well.

22. The magnetometer of claim 21 wherein the SOI structure further includes:

a first conductive structure that extends from the top surface of the SOI structure down into the SOI structure to make an electrical connection with the first well;

a second conductive structure that extends from the top surface of the SOI structure down into the SOI structure to make an electrical connection with the second well;

a third conductive structure that extends from the top surface of the SOI structure down into the SOI structure to make an electrical connection with the first region;

a fourth conductive structure that extends from the top surface of the SOI structure down into the SOI structure to make an electrical connection with the second region; and

an electronic circuit that touches the top surface of the SOI structure.

23. The magnetometer of claim 22 wherein the first die further includes an interconnect structure that touches the top surface of the SOI structure, the interconnect structure electrically connecting the electronic circuit to the first, second, third, and fourth conductive structures and to a number of external electrical connections.

24. The magnetometer of claim 23 wherein the first die further includes an RF coil structure that touches a top surface of the interconnect structure, the RF coil structure having a number of spaced apart coils that lie in a common plane.

Assignments (1)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Sep 12, 2011
From: LINDORFER, PHILIPP; HOPPER, PETER J.; FRENCH, WILLIAM; MAWSON, PAUL; HUNT, STEVEN; PARSA, ROOZBEH
To: NATIONAL SEMICONDUCTOR CORPORATION
Reel/Frame 026888/0004 →
Continuity (1)
Related Publication 20130015850A1 · Jan 17, 2013