Methods of manufacturing a micro-electro-mechanical system (MEMS) structure

• US 8,973,250 B2
• Filed: 06/20/2011
• Issued: 03/10/2015
• Est. Priority Date: 06/20/2011
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Jahnes, Christopher V., Stamper, Anthony K.
• Primary Examiner(s): Kim, Paul D
• Application Number:
  US13/164,323
• Publication Number:
  US 20120319527A1
• Time in Patent Office: 1,359 Days
• Field of Search: 295/921, 296/06, 296/22, 298/25, 298/30, 298/43, 298/46, 298/74, 361/277, 361/278, 361/280, 361/281, 310308-310, 359/224, 359/290, 359/291, 359/295, 359/298, 359/847, 359/848, 359/89, 257/E21.218, 257/415, 257/419, 257/619, 257/684
• US Class Current: 29/594
• CPC Class Codes: B81B 2201/016 having a bridge fixed on two ends and connected to one or more dimples
• CPC Class Codes: B81B 2203/0163 Spring holders
• CPC Class Codes: B81B 3/001 Structures having a reduced contact area, e.g. with bumps or with a textured surface
• CPC Class Codes: B81B 3/0021 Transducers for transforming electrical into mechanical energy or vice versa dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00
• CPC Class Codes: B81B 3/0059 Constitution or structural means for controlling the movement not provided for in groups B81B3/0037 - B81B3/0056
• CPC Class Codes: B81B 3/0072 For controlling internal stress or strain in moving or flexible elements, e.g. stress compensating layers
• CPC Class Codes: B81B 7/0006 Interconnects
• CPC Class Codes: B81B 7/008 MEMS characterised by an electronic circuit specially adapted for controlling or driving the same B81B7/0087 takes precedence; arrangements for starting, regulating, braking, or otherwise controlling an actuator H02N; control arrangements or circuits for visual indicators G09G3/00
• CPC Class Codes: B81C 1/00015 for manufacturing microsystems
• CPC Class Codes: B81C 1/0015 Cantilevers switches using MEMS H01H1/0036; electrostatic relays using micromechanics H01H59/0009; microelectro-mechanical resonators H03H9/02244
• CPC Class Codes: B81C 1/00476 removing a sacrificial layer B81C1/00912 takes precedence
• CPC Class Codes: G06F 30/30 Circuit design
• CPC Class Codes: H10N 30/2042 Cantilevers, i.e. having one fixed end
• CPC Class Codes: H10N 30/304 Beam type
• CPC Class Codes: H10N 30/308 Membrane type
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49005 Acoustic transducer
• CPC Class Codes: Y10T 29/4908 Acoustic transducer
• CPC Class Codes: Y10T 29/49121 Beam lead frame or beam lead device

Abstract

Micro-Electro-Mechanical System (MEMS) structures, methods of manufacture and design structures are provided. The method of forming a MEMS structure includes forming a wiring layer on a substrate comprising actuator electrodes and a contact electrode. The method further includes forming a MEMS beam above the wiring layer. The method further includes forming at least one spring attached to at least one end of the MEMS beam. The method further includes forming an array of mini-bumps between the wiring layer and the MEMS beam.

Claims

1. A method of forming a Micro-Electro-Mechanical System (MEMS) structure, comprising:

forming a wiring layer on a substrate comprising actuator electrodes and a contact electrode;

forming a MEMS beam above the wiring layer;

forming at least one spring attached to at least one end of the MEMS beam; and

forming an array of mini-bumps between the wiring layer and the MEMS beam.

2. The method of claim 1, wherein forming the at least one spring includes forming another spring on another end of the MEMS beam.

3. The method of claim 1, wherein the MEMS beam has a residual stress greater or less than zero such that the MEMS beam moves with respect to the wiring layer on the substrate after the MEMS beam is released.

4. The method of claim 3, further comprising determining a lateral shift of the MEMS beam after release, and based on the determined lateral shift, forming one of a dummy actuator shape or a space between the actuator electrodes so the array of mini-bumps can be aligned with the one of the dummy actuator shape or the space between the actuator electrodes.

5. The method of claim 4, wherein the forming the dummy actuator shape or the space is increased in size based on an increase in the lateral shift of the MEMS beam.

6. The method of claim 4, wherein the array of mini-bumps is formed so as to land on the dummy actuator shape or within the space.

7. The method of claim 4, wherein the array of mini-bumps is placed in a center or nearly in the center of the space or on the dummy actuator shape.

8. The method of claim 4, wherein the size of the dummy actuator shape or the space are designed so that the array of mini-bumps lands on the dummy actuator or the space after the array of mini-bumps move laterally towards a fixed end of the MEMS beam.

9. The method of claim 4, wherein based on the determined lateral shift, forming two or more of a dummy actuator shapes and a space between the actuator electrodes with different lateral shifts of the dummy actuator shapes so the array of mini-bumps can be aligned therewith.

10. The method of claim 3, wherein a size of a landing structure or space to accommodate the array of mini-bumps is increased based on a lateral shift of the MEMS beam due to a temperature change.

11. The method of claim 1, wherein the at least one spring is formed as bendable wires.

12. The method of claim 1, wherein the at least one spring reduces temperature-induced variability in beam shape of the MEMS beam.

13. The method of claim 1, wherein the MEMS beam is asymmetric on ends and the at least one spring flexes laterally.

14. The method of claim 1, wherein the MEMS beam comprises one or more layers of metal and dielectric and the layers have differing thermal expansion coefficients which, over a temperature range, induces beam curvature upwards or downwards, and the at least one spring provides for lateral beam shift when temperature changes, thereby reducing temperature-induced variation in actuation gap or beam curvature.

15. The method of claim 1, wherein the at least one spring is formed with a predetermined spring constant based on a coefficient of thermal expansion (CTE) mismatch between materials of the MEMS beam and the at least one spring is formed to attach to at least one of a top metal and bottom metal of the MEMS beam.

16. The method of claim 1, wherein one of:

the array of mini-bumps is formed in alignment with the actuator electrodes, which are sized to compensate for lateral shift of the MEMS beam;

the array of mini-bumps is formed in alignment with dummy electrodes opposing the MEMS beam, which are sized to compensate for lateral shift of the MEMS beam; and

the array of mini-bumps are formed in alignment with spaces or openings between the actuator electrodes so as to land on a substrate when the MEMS beam is actuated downward, wherein the spaces or openings are sized to compensate for lateral shift of the MEMS beam.

17. The method of claim 1, wherein the array of mini-bumps are formed such that the array of mini-bumps prevents the MEMS beam from contacting the actuator electrodes when the MEMS beam is actuated downward.

18. The method of claim 17, wherein the MEMS beam is formed such that the MEMS beam contacts the contact electrode when the MEMS beam is actuated downward.