Integrated MEMS pressure sensor and MEMS inertial sensor

• US 9,550,668 B1
• Filed: 08/25/2015
• Issued: 01/24/2017
• Est. Priority Date: 08/25/2015
• Status: Active Grant

• Current Assignee: Vanguard International Semiconductor Singapore Pte. Ltd. (Vanguard International Semiconductor Corporation)
• Original Assignee: Globalfoundries Singapore Pte Limited (GlobalFoundries, Inc.)
• Inventors: Xia, Jia Jie, Ranganathan, Nagarajan, Kumar, Rakesh, Chatterjee, Aveek Nath
• Primary Examiner(s): Smoot, Stephen W
• Application Number:
  US14/834,498
• Time in Patent Office: 518 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/0228 Inertial sensors
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 2207/095 through the lid
• CPC Class Codes: B81B 2207/096 through the substrate
• CPC Class Codes: B81B 7/007 Interconnections between the MEMS and external electrical signals
• CPC Class Codes: B81B 7/02 containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS] B81B7/04 takes precedence
• CPC Class Codes: B81C 1/00269 Bonding of solid lids or wafers to the substrate
• CPC Class Codes: B81C 2203/0109 Bonding an individual cap on the substrate
• CPC Class Codes: H01L 29/84 controllable by variation of applied mechanical force, e.g. of pressure

Abstract

Integrated MEMS devices for pressure sensing and inertial sensing, methods for fabricating such integrated devices, and methods for fabricating vertically integrated MEMS pressure sensor/inertial sensor devices are provided. In an example, a method for fabricating an integrated device for pressure and inertial sensing includes forming a MEMS pressure sensor on a first side of a semiconductor substrate. The method further includes forming a MEMS inertial sensor on a second side of the semiconductor substrate. The second side of the semiconductor substrate is opposite the first side of the semiconductor substrate.

Claims

1. A method for fabricating an integrated MEMS device for pressure and inertial sensing, the method comprising:

forming a MEMS pressure sensor on a first side of a semiconductor substrate; and

forming a MEMS inertial sensor on a second side of the semiconductor substrate, wherein the second side of the semiconductor substrate is opposite the first side of the semiconductor substrate.

2. The method of claim 1 further comprising:

forming a membrane in the MEMS pressure sensor on the first side of the semiconductor substrate; and

capping the second side of the semiconductor substrate with a cap to enclose a cavity between the membrane and the cap.

3. The method of claim 1 further comprising:

forming a membrane in the MEMS pressure sensor on the first side of the semiconductor substrate; and

capping the second side of the semiconductor substrate with a cap to enclose a vacuum cavity between the membrane and the cap.

4. The method of claim 3 wherein the semiconductor substrate is a first semiconductor substrate and wherein the method further comprises bonding a second semiconductor substrate to the first side of the first semiconductor substrate.

5. The method of claim 4 further comprising etching through the second semiconductor substrate to form an open cavity in communication with the membrane.

6. The method of claim 1 wherein forming the MEMS inertial sensor on the second side of the semiconductor substrate comprises etching the semiconductor substrate to form a moveable comb structure and moveable proof mass from the semiconductor substrate.

7. The method of claim 1 wherein the semiconductor substrate is a first semiconductor substrate and wherein the method further comprise:

forming a membrane in the MEMS pressure sensor on the first side of the semiconductor substrate; and

bonding a first side of a third semiconductor substrate to the second side of the semiconductor substrate to enclose a cavity between the membrane and the third semiconductor substrate.

8. The method of claim 7 further comprising:

etching vias from the first side of the first semiconductor substrate to a second side of the third semiconductor substrate; and

forming conductive interconnects from the first side of the first semiconductor substrate to the second side of the third semiconductor substrate.

9. The method of claim 1 wherein forming the MEMS pressure sensor on the first side of the semiconductor substrate comprises:

forming a backplate member over a sacrificial layer in the first side of the semiconductor substrate; and

forming a membrane over the backplate member.

10. The method of claim 9 wherein forming the MEMS inertial sensor on the second side of the semiconductor substrate comprises:

etching through the semiconductor substrate to the sacrificial layer; and

removing the sacrificial layer to form a comb structure and proof mass from the semiconductor substrate.

11. A method for fabricating a vertically integrated MEMS pressure sensor/inertial sensor device, the method comprising:

providing a semiconductor substrate;

processing a first side of the semiconductor substrate to form a MEMS pressure sensor; and

processing a second side of the semiconductor substrate to form a MEMS inertial sensor.

12. The method of claim 11 wherein processing the first side of the semiconductor substrate and processing the second side of the semiconductor substrate comprises forming a cavity in the semiconductor substrate shared by the MEMS pressure sensor and the MEMS inertial sensor.

13. The method of claim 12 wherein the cavity is bound by a membrane formed on the first side of the semiconductor substrate and a cap formed on the second side of the semiconductor substrate.

14. The method of claim 11 wherein:

processing the first side of the semiconductor substrate to form the MEMS pressure sensor comprises forming a membrane on the first side of the semiconductor substrate; and

processing the second side of the semiconductor substrate to form the MEMS inertial sensor comprises forming cavity through the semiconductor substrate, wherein the cavity is bounded by the membrane and shared by the MEMS pressure sensor and the MEMS inertial sensor.

15. The method of claim 11 wherein the semiconductor substrate is a first semiconductor substrate and wherein the method further comprises:

bonding a second semiconductor substrate to the first side of the first semiconductor substrate; and

etching through the second semiconductor substrate to form an open cavity.

16. The method of claim 11 wherein processing the second side of the semiconductor substrate to form the MEMS inertial sensor comprises etching the semiconductor substrate to form a moveable comb structure and moveable proof mass from the semiconductor substrate.

17. The method of claim 11 wherein the semiconductor substrate is a first semiconductor substrate and wherein the method further comprises:

bonding a first side of a third semiconductor substrate to the second side of the first semiconductor substrate to enclose a cavity in the semiconductor substrate;

etching vias from the first side of the first semiconductor substrate to a second side of the third semiconductor substrate; and

forming conductive interconnects from the first side of the first semiconductor substrate to the second side of the third semiconductor substrate.

18. The method of claim 11 wherein processing the first side of the semiconductor substrate to form the MEMS pressure sensor comprises:

forming a backplate member over a sacrificial layer in the first side of the semiconductor substrate; and

forming a membrane over the backplate member.

19. The method of claim 18 wherein processing the second side of the semiconductor substrate to form the MEMS inertial sensor comprises:

etching through the semiconductor substrate to the sacrificial layer; and

removing the sacrificial layer to form a comb structure and proof mass from the semiconductor substrate.

20. An integrated MEMS device for pressure sensing and inertial sensing comprising:

a semiconductor substrate having a first side and a second side opposite the first side;

a MEMS pressure sensor located on the first side of the semiconductor substrate; and

a MEMS inertial sensor located on the second side of the semiconductor substrate.