Sequential wafer bonding

• US 9,090,454 B2
• Filed: 08/27/2013
• Issued: 07/28/2015
• Est. Priority Date: 08/27/2013
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Bowles, Philip H., Hooper, Stephen R.
• Primary Examiner(s): HUBER, ROBERT T
• Application Number:
  US14/011,289
• Publication Number:
  US 20150061044A1
• Time in Patent Office: 700 Days
• Field of Search: 257/415, 257/E23.193, 257/E21.705, 438/50, 438/51, 438/455, 438/456, 438/458, 737/54
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2207/012 the micromechanical device and the control or processing electronics being separate parts in the same package
• 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 7/04 Networks or arrays of similar microstructural devices
• CPC Class Codes: B81C 1/0023 Packaging together an electronic processing unit die and a micromechanical structure die MEMS packages B81B7/0032; MEMS packaging processes B81C1/00261
• CPC Class Codes: B81C 1/00293 maintaining a controlled atmosphere with processes not provided for in B81C1/00285
• CPC Class Codes: B81C 2203/0145 Hermetically sealing an opening in the lid
• CPC Class Codes: H01L 2224/11 Manufacturing methods
• CPC Class Codes: H01L 23/10 characterised by the material or arrangement of seals between parts, e.g. between cap and base of the container or between leads and walls of the container
• CPC Class Codes: H01L 29/66007 Multistep manufacturing processes
• CPC Class Codes: H01L 29/84 controllable by variation of applied mechanical force, e.g. of pressure
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

Embodiments of methods of fabricating a sensor device includes attaching a first wafer to a sensor wafer with a first bond material, and attaching a second wafer to the sensor wafer with a second bond material, the second bond material having a lower bonding temperature than the first bond material. After attaching the second wafer, an opening (e.g., a trench cut) through the second wafer is formed, and an adhesive material is provided through the opening to further secure the second wafer to the sensor wafer. Embodiments of sensor devices formed using such methods include a first device cavity having a first pressure, and a second device cavity having a second pressure.

Claims

1. A method of fabricating a sensor device, the method comprising:

attaching a first wafer to a sensor wafer with a first bond material;

attaching a second wafer to the sensor wafer with a second bond material, the second bond material having a lower bonding temperature than the first bond material;

after attaching the second wafer, forming an opening through the second wafer; and

providing an adhesive material through the opening to further secure the second wafer to the sensor wafer.

2. The method of claim 1, wherein the first bond material comprises an aluminum-germanium (AlGe) alloy.

3. The method of claim 1, wherein the second bond material is selected from the group consisting of a tin-silver-copper (SnAgCu) alloy, a tin-antimony (SnSb) alloy, a lead-tin (PbSn) alloy, and a lead-tin-silver (PbSnAg) alloy.

4. The method of claim 3, wherein:

the second bond material is arranged as a sealing ring disposed along a die perimeter on the sensor wafer; and

the opening is disposed outside of the sealing ring.

5. The method of claim 1, wherein:

forming the opening comprises implementing a trench cut through the second wafer, which forms a groove in the sensor wafer; and

providing the adhesive material fills the groove in the sensor wafer with the adhesive material.

6. The method of claim 5, wherein the trench cut is positioned along a die scribe line.

7. The method of claim 1, further comprising attaching solder balls to the first wafer or the second wafer, the solder balls having a bonding temperature no lower than the bonding temperature of the second bond material.

8. The method of claim 1, further comprising attaching solder balls to the first wafer or the second wafer, the solder balls comprising the second bond material.

9. The method of claim 1, wherein:

attaching the first wafer is implemented at a first pressure to define a first device cavity at the first pressure for a die on the sensor wafer; and

attaching the second wafer is implemented at a second pressure higher than the first pressure to define a second device cavity at the second pressure for the die.

10. The method of claim 9, further comprising, before attaching the second wafer, forming a vent hole through the sensor wafer, wherein the second bond material is arranged in a seal ring disposed between the adhesive material and the vent hole.

11. The method of claim 1, wherein the adhesive material comprises an underfill epoxy material.

12. A method of fabricating a sensor device, the method comprising:

attaching a first cap wafer to a sensor wafer with a first bond material, the sensor wafer comprising a plurality of die, the first bond material being arranged to define a first device cavity for each die of the plurality of die;

attaching a second cap wafer to the sensor wafer with a second bond material, the second bond material being arranged to define a second device cavity for each die of the plurality of die, the second bond material having a lower bonding temperature than the first bond material;

after attaching the second cap wafer, forming one or more openings through the second cap wafer along die scribe lines; and

providing an underfill material through the one or more openings to further secure the second cap wafer to the sensor wafer.

13. The method of claim 12, wherein the first bond material comprises an aluminum-germanium (AlGe) alloy, and wherein the second bond material is selected from the group consisting of a tin-silver-copper (SnAgCu) alloy, a tin-antimony (SnSb) alloy, a lead-tin (PbSn) alloy, and a lead-tin-silver (PbSnAg) alloy.

14. The method of claim 12, wherein:

the second bond material is arranged in a respective sealing ring disposed along a perimeter of each die; and

each opening formed by one of the trench cuts is disposed outside of the respective sealing ring.

15. The method of claim 12, wherein:

forming the one or more openings comprises implementing one or more trench cuts, which forms one or more grooves in the sensor wafer; and

providing the underfill material fills the one or more grooves in the sensor wafer with the underfill material.