MICROELECTROMECHANICAL SYSTEM (MEMS) DEVICE AND FABRICATION METHOD THEREOF

• US 20140077317A1
• Filed: 09/14/2012
• Published: 03/20/2014
• Est. Priority Date: 09/14/2012
• Status: Active Grant

• Current Assignee: Solid State System Co., Ltd.
• Original Assignee: Solid State System Co., Ltd.
• Inventors: Hsieh, Tsung-Min, Lee, Chien-Hsing, Liou, Jhyy-Cheng
• Granted Patent: US 8,987,842 B2
• Time in Patent Office: Days
• US Class Current: 257/416
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81B 3/00 Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes B81B5/00 takes precedence
• CPC Class Codes: B81B 3/0013 Structures dimensioned for mechanical prevention of stiction, e.g. spring with increased stiffness
• CPC Class Codes: B81B 7/00 Microstructural systems; Auxiliary parts of microstructural devices or systems
• 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 1/00158 Diaphragms, membranes manufacture process for semi-permeable inorganic membranes B01D67/0039
• CPC Class Codes: B81C 1/00952 Treatments or methods for avoiding stiction during the manufacturing process not provided for in groups B81C1/00928 - B81C1/00944
• CPC Class Codes: H04R 19/005 using semiconductor materials
• CPC Class Codes: H04R 2201/003 Mems transducers or their use of the electrostatic type H04R19/005

Abstract

A MEMS device includes a silicon substrate and a structural dielectric layer. The silicon substrate has a cavity. The structural dielectric layer is disposed on the silicon substrate. The structural dielectric layer has a space above the cavity of the silicon substrate and holds a plurality of structure elements within the space, including: a conductive backplate, over the silicon substrate, having a plurality of venting holes and a plurality of protrusion structures on top of the conductive backplate; and a diaphragm, located above the conductive backplate by a distance, wherein a chamber is formed between the diaphragm and the conductive backplate, and is connected to the cavity of the silicon substrate through the venting holes. A first side of the diaphragm is exposed by the chamber and faces to the protrusion structures of the conductive backplate and a second side of the diaphragm is exposed to an environment space.

Claims

1. A microelectromechanical system (MEMS) device, comprising:

a silicon substrate, having a cavity; and

a structural dielectric layer, disposed on the silicon substrate, wherein the structural dielectric layer has a space above the cavity of the silicon substrate and holds a plurality of structure elements within the space, comprising;

a conductive backplate, over the silicon substrate, having a plurality of venting holes and a plurality of protrusion structures on top of the conductive backplate; and

a diaphragm, located above the conductive backplate by a distance, wherein a chamber is formed between the diaphragm and the conductive backplate, and is connected to the cavity of the silicon substrate through the venting holes,

wherein a first side of the diaphragm is exposed by the chamber and faces to the protrusion structures of the conductive backplate and a second side of the diaphragm is exposed to an environment space.

2. The MEMS device of claim 1, wherein the diaphragm comprises a first layer and a second layer and a portion of the structural dielectric layer enclosed between the first layer and a second layer.

3. The MEMS device of claim 2, wherein the first layer and the second layer enclosing the structural dielectric layer are conductive.

4. The MEMS device of claim 1, wherein the diaphragm is a corrugated structure.

5. The MEMS device of claim 1, wherein the diaphragm also has at least an opening, for connecting the chamber to the environment space.

6. The MEMS device of claim 1, wherein the conductive backplate comprises parallel multilevel conductive layers and a dielectric layer filled between the conductive layers.

7. The MEMS device of claim 6, further comprising a capping layer on the conductive backplate layer to cover a sidewall of the conductive backplate, wherein the capping layer has an etching rate lower than an etching rate of the dielectric layer.

8. The MEMS device of claim 1, wherein the conductive backplate comprises parallel multilevel conductive layers, a vertical conductive layer vertical to the conductive layers, and a dielectric layer filled between the parallel multilevel conductive layers and the vertical conductive layer.

9. The MEMS device of claim 8, further comprising a capping layer on the conductive backplate layer to cover a sidewall of the conductive backplate layer, wherein the capping layer has an etching rate lower than an etching rate of the dielectric layer.

10. The MEMS device of claim 1, further comprising a passivation layer on top of the structural dielectric layer, the passivation layer has an opening to expose the second side of the diaphragm and is lower in etching rate than the structural dielectric layer.

11. A microelectromechanical system (MEMS) device, comprising:

a silicon substrate, having a cavity;

a structural dielectric layer, disposed on the silicon substrate; and

a passivation layer on the structural dielectric layer, the passivation layer has an opening over the cavity of the silicon substrate,

wherein the structural dielectric layer has a MEMS space and holds a plurality of structure elements within the MEMS space, comprises;

a first conductive layer, disposed over the silicon substrate, wherein the first conductive layer has a plurality of venting holes above the cavity of the silicon substrate;

a supporting layer, disposed on the first conductive layer, surrounding the venting holes;

a second conductive layer, disposed on the supporting layer;

a plurality of protrusion structures, disposed on the second conductive layer within a region above the cavity of the silicon substrate;

a cap layer, capping over the first conductive layer, the supporting layer, the second conductive layer and the protrusion structures; and

a diaphragm, located above the second conductive layer by a distance, wherein a chamber is formed between the diaphragm and the cap protection layer and is connected to the cavity of the silicon substrate through the venting holes,

wherein portions of the diaphragm, the first conductive layer and the cap layer within the MEMS space are exposed.

12. The MEMS device of claim 11, wherein the diaphragm comprises a first layer and a second layer and a portion of the structural dielectric layer enclosed between the first layer and a second layer.

13. The MEMS device of claim 11, wherein the diaphragm also has at least an opening, for connecting the chamber to the environment space.

14. The MEMS device of claim 11, wherein the passivation layer is lower in etching rate than a dielectric material of the structural dielectric layer.

15. The MEMS device of claim 11, wherein the supporting layer includes a plurality of ring layers, and each of the venting holes is surrounded by at least one of the ring layers.

16. The MEMS device of claim 11, wherein the supporting layer includes a plurality of supporting structure units, distributed around the venting holes.

17. The MEMS device of claim 11, wherein a portion of the structural dielectric layer fills an inner space enclosed between the cap layer, the first conductive layer, and the second conductive layer.

18. The MEMS device of claim 11, wherein the cap layer is lower in etching rate than a dielectric material of the structural dielectric layer.

19. The MEMS device of claim 11, where the diaphragm is a corrugated structure.

20. A method for fabricating microelectromechanical system (MEMS) device, comprising:

providing a silicon substrate having a first side and a second side;

forming a structural dielectric layer over the first side of the silicon substrate, wherein a plurality of structure elements is embedded in the structural dielectric layer and to be released, the structure elements comprise;

a conductive backplate, over the silicon substrate, having a plurality of venting holes and a plurality of protrusion structures on a top of the conductive backplate; and

a diaphragm, located above the conductive backplate by a distance, wherein a chamber is formed between the diaphragm and the conductive backplate;

forming a cavity in the silicon substrate at the second side, wherein the cavity is corresponding to the structure elements embedded in the structural dielectric layer; and

performing isotropic etching process on a dielectric material of the structural dielectric layer to release the structure elements,

wherein a first side of the diaphragm is exposed by the chamber and faces to the protrusion structures of the conductive backplate and a second side of the diaphragm is exposed to an environment space, wherein the chamber is connected to the cavity of the silicon substrate through the venting holes of the conductive backplate.

21. The method for fabricating MEMS device of claim 20, wherein the diaphragm is formed to comprise a first layer and a second layer and a portion of the structural dielectric layer enclosed between the first layer and a second layer.

22. The method for fabricating MEMS device of claim 20, where in the diaphragm is a corrugated structure.

23. The method for fabricating MEMS device of claim 20, wherein the diaphragm is further formed to have at least an opening, for connecting the chamber to the environment space.

24. The method for fabricating MEMS device of claim 20, further forming a passivation layer on top of the structural dielectric layer, the passivation layer has an opening to expose the second side of the diaphragm and is lower in etching rate than the structural dielectric layer.

25. A method for fabricating microelectromechanical system (MEMS) device, comprising:

providing a silicon substrate, having a first side and a second side;

forming a structural dielectric layer on the first side of the silicon substrate, wherein a plurality of structure elements is embedded in the structural dielectric layer and to be released, the structure elements comprise;

a first conductive layer, formed over the silicon substrate, wherein the first conductive layer has a plurality of venting holes;

a supporting layer, formed on the first conductive layer, surrounding the venting holes;

a second conductive layer, formed on the supporting layer;

a plurality of protrusion structures, formed on the second conductive layer;

a cap layer, capping over the first conductive layer, the supporting layer, the second conductive layer and the protrusion structures; and

a diaphragm, formed above the second conductive layer by a distance, wherein a chamber is formed between the diaphragm and the cap protection layer and is connected to the cavity of the silicon substrate through the venting holes;

forming a passivation layer over the structural dielectric layer, wherein the passivation layer has an opening to expose the structural dielectric layer at a MEMS region;

forming a cavity in the silicon substrate at the second side to expose the structural dielectric layer; and

performing isotropic etching process on a dielectric material of the structural dielectric layer to release the structure elements,

wherein a first side of the diaphragm is exposed by the chamber and faces to the protrusion structures of the conductive backplate and a second side of the diaphragm is exposed to an environment space, wherein the chamber is connected to the cavity of the silicon substrate through the venting holes of the conductive backplate.

26. The method for fabricating MEMS device of claim 25, wherein the diaphragm comprises a first layer and a second layer and a portion of the structural dielectric layer enclosed between the first layer and a second layer.

27. The method for fabricating MEMS device of claim 25, where the diaphragm is a corrugated structure.

28. The method for fabricating MEMS device of claim 25, wherein the diaphragm also has at least an opening, for connecting the chamber to the environment space.

29. The method for fabricating MEMS device of claim 25, wherein the passivation layer is lower in etching rate than a dielectric material of the structural dielectric layer.

30. The method for fabricating MEMS device of claim 25, wherein the supporting layer includes a plurality of ring layers, and each of the venting holes is surrounded by at least one of the ring layers.

31. The method for fabricating MEMS device of claim 25, wherein the supporting layer includes a plurality of supporting structure units, distributed around the venting holes.

32. The method for fabricating MEMS device of claim 25, wherein a portion of the structural dielectric layer fills an inner space enclosed between the cap layer, the first conductive layer, and the second conductive layer.

33. The method for fabricating MEMS device of claim 25, wherein the cap layer is lower in etching rate than a dielectric material of the structural dielectric layer.