MEMS STRESS CONCENTRATING STRUCTURE FOR MEMS SENSORS

• US 20110048138A1
• Filed: 09/01/2010
• Published: 03/03/2011
• Est. Priority Date: 09/02/2009
• Status: Active Grant

• Current Assignee: Kontel Data System Limited
• Original Assignee: Kontel Data System Limited
• Inventors: Li, Ping Wai
• Granted Patent: US 8,733,176 B2
• Time in Patent Office: Days
• US Class Current: 73/721
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 3/0086 Electrical characteristics, e.g. reducing driving voltage, improving resistance to peak voltage
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively
• CPC Class Codes: G01L 9/0054 integral with a semiconducting diaphragm
• CPC Class Codes: H04R 17/00 Piezoelectric transducers; Electrostrictive transducers piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners H10N30/00
• CPC Class Codes: H04R 2201/003 Mems transducers or their use of the electrostatic type H04R19/005
• CPC Class Codes: H04R 23/006 using solid state devices solid state devices per se H01L
• CPC Class Codes: H04R 31/00 Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor manufacture of microstructural arrangements of deformable or non-deformable structures in general B81C1/00182
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A stress concentrating apparatus and a method for a MicroElectroMechanical System (MEMS) sensors is provided. The apparatus includes a plate having an inner region and outer region, the inner region being separated from the outer region by slits defined in the plate. A stress concentrator bridge connects the inner region to the outer region, and to mechanically amplify stress applied on the inner region of the plate. At least one stress sensor is operatively connected to the stress concentrator bridge, whereby the at least one stress sensor converts the mechanically amplified stress applied on the inner region into an electrical signal.

Claims

1. A stress concentrating apparatus for MicroElectroMechanical System (MEMS) sensors, the apparatus comprising:

a plate having an inner region and outer region, the inner region being separated from the outer region by slits defined in the plate;

a stress concentrator bridge configured to connect the inner region to the outer region and configured to mechanically amplify stress applied on the inner region of the plate; and

at least one stress sensor operatively connected to the stress concentrator bridge,

wherein the at least one stress sensor converts the mechanically amplified stress applied on the inner region into an electrical signal.

2. The apparatus according to claim 1, wherein the slits are etched into the plate

3. The apparatus according to claim 1, wherein the at least one stress sensor is built into the stress concentrator bridge, attached on any surface of the stress concentrator bridge or embedded within the stress concentrator bridge.

4. The apparatus according to claim 1, wherein the inner region is thinner than the outer region.

5. The apparatus according to claim 1, wherein the plate is a single plate of silicon.

6. The apparatus according to claim 1, wherein the stress concentrator bridge has a constant cross-section along a length thereof.

7. The apparatus according to claim 6, wherein the cross-section of the stress concentrator bridge is rectangular or oval.

8. The apparatus according to claim 1, wherein the stress concentrator bridge has at least one piezo-junction transistor or piezo-resistive element, the piezo-junction transistor or piezo-resistive element having low power consumption and optimizes noise.

10. A method for manufacturing the stress concentrating apparatus of claim 1, the method comprising:

thinning down an inner region of the plate;

etching slits into the silicon plate to separate the inner region from the outer region; and

connecting the inner region to the outer region with at least one stress concentrator bridge.

11. The method according to claim 10, wherein the stress concentrator bridges are formed by etching slits in the plate to form lateral sides of the stress concentrator bridges.

12. The method according to claim 10, further comprising forming cross-sections having substantially the same or different thickness along a length of the stress concentrator bridges to further focus stress.

13. The method according to claim 10, wherein, if the stress sensing device is a pressure sensor, the method further comprises refilling the slits with a substance or compound to separate upper and lower regions of the plate into two air-tight regions for sensing pressure.

14. The method according to claim 10, wherein the inner region of the silicon plate is thinned down by wet chemical etching or dry reactive ion etching

15. The method according to claim 10, wherein the stress concentrator bridges have at least one stress sensor that is a piezo-resistor, a piezojunction transistor, or a piezo field effect transistor.

9. A method for concentrating stress for MicroElectroMechanical System (MEMS) sensors, the method comprising:

mechanically amplifying stress applied on a inner region of a stress sensing device; and

converting the mechanically amplified stress applied on the inner region into an electrical signal.