MEMS Device Structure and Methods of Forming Same

• US 20130277777A1
• Filed: 04/18/2012
• Published: 10/24/2013
• Est. Priority Date: 04/18/2012
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Fan, Chen-Chih, Chou, Bruce C.S., Chang, Chang-Chia
• Granted Patent: US 9,139,420 B2
• Time in Patent Office: Days
• US Class Current: 257/418
• CPC Class Codes: B81B 2201/0228 Inertial sensors
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/025 Inertial sensors not provided for in B81B2201/0235 - B81B2201/0242
• CPC Class Codes: B81B 2207/07 Interconnects
• CPC Class Codes: B81B 2207/096 through the substrate
• CPC Class Codes: B81B 3/0018 Structures acting upon the moving or flexible element for transforming energy into mechanical movement or vice versa, i.e. actuators, sensors, generators
• CPC Class Codes: B81B 3/0067 Mechanical properties
• CPC Class Codes: B81B 3/007 For controlling stiffness, e.g. ribs
• CPC Class Codes: B81B 7/00 Microstructural systems; Auxiliary parts of microstructural devices or systems
• CPC Class Codes: B81B 7/0006 Interconnects
• CPC Class Codes: B81B 7/0016 Protection against shocks or vibrations, e.g. vibration damping
• CPC Class Codes: B81B 7/0029 Protection against environmental influences not provided for in groups B81B7/0012 - B81B7/0025
• CPC Class Codes: B81B 7/0041 maintaining a controlled atmosphere with techniques not provided for in B81B7/0038
• CPC Class Codes: B81B 7/0051 between the package lid and the substrate
• CPC Class Codes: B81B 7/0058 for protecting against damages due to external chemical or mechanical influences, e.g. shocks or vibrations
• CPC Class Codes: B81C 1/00 Manufacture or treatment of devices or systems in or on a substrate B81C3/00 takes precedence
• CPC Class Codes: B81C 1/00269 Bonding of solid lids or wafers to the substrate
• CPC Class Codes: B81C 1/00293 maintaining a controlled atmosphere with processes not provided for in B81C1/00285
• CPC Class Codes: B81C 1/00325 for reducing stress inside of the package structure
• CPC Class Codes: B81C 2203/0118 Bonding a wafer on the substrate, i.e. where the cap consists of another wafer

Abstract

A microelectromechanical system (MEMS) device may include a MEMS structure above a first substrate. The MEMS structure comprising a central static element, a movable element, and an outer static element. A portion of bonding material between the central static element and the first substrate. A second substrate above the MEMS structure, with a portion of a dielectric layer between the central static element and the second substrate. A supporting post comprises the portion of bonding material, the central static element, and the portion of dielectric material.

Claims

1. A method for forming a microelectromechanical system (MEMS) device comprising:

forming a MEMS structure over a first substrate, wherein the MEMS structure comprises a movable element and an adjacent static element;

forming a cavity surrounding the movable element;

forming an interconnect structure on a second substrate;

depositing a first dielectric layer on the interconnect structure; and

bonding the MEMS structure to the first dielectric layer, wherein the static element forms a first supporting post in the cavity, the first supporting post configured to support the second substrate.

2. The method of claim 1, wherein the bonding further forms a second supporting post in the cavity, wherein the second supporting post is laterally spaced from the first supporting post, the second supporting post configured to support the second substrate.

3. The method of claim 1, wherein the movable element is not supported by the first supporting post.

4. The method of claim 1 further comprising:

before the forming the interconnect structure, forming a contact pad on a top surface of the second substrate;

thinning a backside of the second substrate;

forming an opening in the backside of the second substrate, wherein a bottom surface of the opening adjoins the contact pad;

depositing a conductive material on the backside of the second substrate and in the opening; and

patterning the conductive material to form a via in the opening and contact pads on the backside of the second substrate.

5. The method of claim 1, wherein the bonding further comprises:

depositing a first bonding material on the MEMS structure;

depositing a second bonding material on the first dielectric layer;

bringing the first bonding material and the second bonding material into contact;

creating a hermetic seal and electrical connection between the first bonding material and the second bonding material; and

creating a vacuum in the cavity.

6. The method of claim 5, wherein the first supporting post comprises:

a portion of the first bonding material;

a portion of the second bonding material; and

the static element of the MEMS structure.

7. The method of claim 1 further comprising:

the forming the MEMS structure further comprises;

depositing a second dielectric layer on the first substrate;

forming openings in the second dielectric layer;

depositing a protective component in the openings;

bonding a MEMS wafer to the second dielectric layer;

patterning the MEMS wafer to form the movable element, wherein the movable element encircles a central static element, and the movable element is encircled by an outer static element; and

the forming the cavity further comprises;

removing portions of the second dielectric layer between the movable element and the first substrate, wherein the removed portions of the second dielectric layer are not protected by the protective component, and the removing forms a central portion of the second dielectric layer between the first substrate and the central static element.

8. The method of claim 7, wherein the central portion of the dielectric layer is between two protective components.

9. The method of claim 1, wherein the forming the cavity further comprises:

recessing the first substrate; and

removing portions of the first dielectric layer.

10. A method of forming a MEMS device comprising:

forming an interconnect structure on a first substrate;

depositing a dielectric layer on the interconnect structure;

patterning the dielectric layer to form a central portion and two outer portions;

bonding a MEMS wafer to the patterned dielectric layer;

patterning the MEMS wafer to form a movable element, a central static element, and an outer static element, the movable element encircling the central static element, and the outer static element encircling the movable element;

depositing a first bonding material on the central static element and the outer static element;

forming two recesses in a second substrate, wherein the recesses form a central raised portion of the second substrate and two outer raised portions of the second substrate;

depositing a second bonding material on the central raised portion and the outer raised portions of the second substrate; and

bonding the MEMS wafer to the second substrate, wherein the central portion of the dielectric layer, the central static element, the first bonding material on the central static element, the second bonding material on the central raised portion, and the central raised portion form a first supporting post.

11. The method of claim 10 further comprising:

before the forming the interconnect structure, forming a contact pad on a top surface of the first substrate;

thinning a backside of the first substrate;

thinning a backside of the second substrate;

forming an opening in the backside of the first substrate, wherein a bottom surface of the opening adjoins the contact pad;

depositing a conductive material on the backside of the first substrate and in the opening; and

patterning the conductive material to form a via in the opening and contact pads on the backside of the first substrate.

12. The method of claim 10, wherein the bonding further comprises:

forming a cavity above and below the MEMS wafer, the cavity surrounding the first supporting post.

13. The method of claim 12, wherein the bonding the MEMS wafer to the second substrate forms a second supporting post in the cavity, wherein the second supporting post is laterally spaced from the first supporting post.

14. A MEMS device comprising:

a MEMS structure above a first substrate, wherein the MEMS structure comprises a movable element, a central static element, and an outer static element, wherein the movable element is suspended above the first substrate, the movable element is laterally separated from the outer static element by a first spacing, and the movable element is laterally separated from the central static element by a second spacing;

a central portion of a bonding material between the first substrate and a bottom surface of the central static element;

a second substrate above the MEMS structure;

a central portion of a first dielectric layer between the second substrate and a top surface of the central static element; and

a supporting post, the supporting post comprising;

the central portion of the bonding material, the central static element, and the central portion of the first dielectric layer.

15. The MEMS device of claim 14 further comprising:

a first outer portion of the first dielectric layer, the first outer portion between the outer static element and the second substrate;

a second outer portion of the first dielectric layer, the second outer portion between the outer static element and the second substrate;

a first outer portion of a protective component, the first outer portion of the protective component between the outer static element and the second substrate, and the first outer portion of the protective component adjacent the first outer portion of the dielectric layer;

a second outer portion of the protective component, the second outer portion of the protective component between the outer static element and the second substrate, and the second outer portion of the protective component adjacent the second outer portion of the first dielectric layer; and

a first inner portion and a second inner portion of the protective component, the first and second inner portions of the protective components adjoining opposite sides of the central portion of the first dielectric layer.

16. The MEMS device of claim 15 further comprising:

an upper portion of a cavity, the upper portion above the movable element; and

a lower portion of the cavity, the lower portion below the movable element, wherein the lower portion adjoins the upper portion in the first spacing and the second spacing.

17. The MEMS device of claim 14, wherein the movable element is not supported by the supporting post.

18. The MEMS device of claim 14, wherein the movable element encircles the central static element and the outer static element encircles the movable element.

19. The MEMS device of claim 14 further comprising:

an interconnect structure on a top surface of the first substrate;

a second dielectric layer on the interconnect structure, the second dielectric layer between the interconnect structure and the central portion of the bonding material; and

a through substrate via (TSV) in the first substrate, the TSV electrically coupled to a metal feature in the interconnect structure.

20. The MEMS device of claim 14, wherein the supporting post further comprises a raised portion of the second substrate, the raised portion above the central portion of the first dielectric layer.