Method for manufacturing a micro-electro-mechanical device

• US 7,534,641 B2
• Filed: 09/29/2005
• Issued: 05/19/2009
• Est. Priority Date: 09/29/2005
• Status: Expired due to Fees

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Chilcott, Dan W.
• Primary Examiner(s): PHAM, THANHHA S
• Application Number:
  US11/238,855
• Publication Number:
  US 20070072331A1
• Time in Patent Office: 1,328 Days
• Field of Search: 438/456, 438/459, 438/455, 438/50, 438 52- 53, 438/118, 257/E21.532, 257/E21.533, 257/E21.567, 257/E21.573
• US Class Current: 438/53
• CPC Class Codes: B81B 2203/0127 Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function
• CPC Class Codes: B81C 1/00246 Monolithic integration, i.e. micromechanical structure and electronic processing unit are integrated on the same substrate
• CPC Class Codes: B81C 1/00666 Treatments for controlling internal stress or strain in MEMS structures
• CPC Class Codes: B81C 2201/0191 Transfer of a layer from a carrier wafer to a device wafer
• CPC Class Codes: B81C 2203/0728 Pre-CMOS, i.e. forming the micromechanical structure before the CMOS circuit

Abstract

A technique for manufacturing a micro-electro-mechanical (MEM) device includes a number of steps. Initially, a first wafer is provided. Next, a bonding layer is formed on a first surface of the first wafer. Then, a portion of the bonding layer is removed to provide a cavity including a plurality of spaced support pedestals within the cavity. Next, a second wafer is bonded to at least a portion of the bonding layer. A portion of the second wafer provides a diaphragm over the cavity and the support pedestals support the diaphragm during processing. The second wafer is then etched to release the diaphragm from the support pedestals.

Claims

1. A method for manufacturing a micro-electro-mechanical (MEM) device, comprising the steps of:

providing a first wafer;

removing a portion of the first wafer to provide a cavity including a plurality of spaced support pedestals within the cavity;

bonding a second wafer to at least a portion of the first wafer, wherein a portion of the second wafer provides a diaphragm over the cavity, and wherein the support pedestals support the diaphragm during processing;

etching the second wafer to release the diaphragm from the support pedestals; and

etching at least a portion of the diaphragm adjacent a sidewall of the cavity to allow the diaphragm to move and to provide the (MEM) device that is compatible with a complementary metal-oxide semiconductor (CMOS) process wherein the support pedestals are spaced in a regular pattern such that the cavity is provided without creating stress limit at temperature.

2. The method of claim 1, wherein the first wafer is a handle wafer and the second wafer is an active wafer, and wherein the handle and active wafers are silicon wafers.

3. The method of claim 2, further comprising the step of:

thinning the active wafer to provide a desired thickness for the diaphragm.

4. The method of claim 1, wherein the support pedestals are not bonded to the second wafer.

5. The method of claim 1, wherein the first wafer is an active wafer and the second wafer is a handle wafer, and wherein the handle and active wafers are silicon wafers.

6. The method of claim 1, wherein the support pedestals support the diaphragm during processing to prevent plastic deformation of the diaphragm.

7. The method of claim 1, wherein the support pedestals remain within the cavity.

8. A method for manufacturing a micro-electro-mechanical (MEM) device, comprising the steps of:

providing a first wafer;

forming a bonding layer on a first surface of the first wafer;

removing a portion of the bonding layer to provide a cavity including a plurality of spaced support pedestals within the cavity, wherein the spaced support pedestals are recessed;

bonding a second wafer to at least a portion of the bonding layer, wherein a portion of the second wafer provides a diaphragm over the cavity, and wherein the support pedestals support the diaphragm during processing; and

etching at least a portion of the diaphragm adjacent a sidewall of the cavity to allow the diaphragm to move, wherein the support pedestals remain in the cavity, thereby providing the (MEM) device that is compatible with a complementary metal-oxide semiconductor (CMOS) process wherein the support pedestals are spaced in a regular pattern such that the cavity is provided without creating stress limit at temperature.

9. The method of claim 8, wherein the first wafer is a handle wafer and the second wafer is an active wafer, and wherein the handle and active wafers are silicon wafers.

10. The method of claim 8, wherein the support pedestals are not bonded to the second wafer.

11. The method of claim 8, wherein the bonding layer is made of silicon, an oxide or a nitride.

12. The method of claim 8, wherein the support pedestals support the diaphragm during processing to prevent plastic deformation of the diaphragm.

13. A method for manufacturing a micro-electro-mechanical (MEM) device, comprising the steps of:

providing a handle wafer;

forming a bonding layer on a first surface of the handle wafer;

removing a portion of the bonding layer to provide a cavity including a plurality of

spaced support pedestals within the cavity;

bonding an active wafer to at least a portion of the bonding layer, wherein a portion of the active wafer provides a diaphragm over the cavity, and wherein the support pedestals support the diaphragm;

etching the active wafer to release the diaphragm from the support pedestals, wherein the support pedestals remain within the cavity; and

etching at least a portion of the diaphragm adjacent a sidewall of the cavity to allow the diaphragm to move and to provide the (MEM) device that is compatible with a complementary metal-oxide semiconductor (CMOS) process wherein the support pedestals are spaced in a regular pattern such that the cavity is provided without creating stress limit at temperature.

14. The method of claim 13, wherein the handle and active wafers are silicon wafers.

15. The method of claim 13, wherein the bonding layer is made of silicon, an oxide or a nitride.

16. The method of claim 13, wherein the support pedestals support the diaphragm during processing to prevent plastic deformation of the diaphragm.

17. The method of claim 13, further comprising the step of:

thinning the active wafer to provide a desired thickness for the diaphragm.