Microelectronic packages having stacked accelerometer and magnetometer die and methods for the production thereof

• US 9,108,841 B1
• Filed: 03/05/2014
• Issued: 08/18/2015
• Est. Priority Date: 03/05/2014
• 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): Kusumakar, Karen
• Application Number:
  US14/197,962
• Publication Number:
  US 20150251903A1
• Time in Patent Office: 531 Days
• Field of Search: 438106-127, 73488-551, 36167901-821
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2201/0292 Sensors not provided for in B81B2201/0207 - B81B2201/0285
• CPC Class Codes: B81B 2207/096 through the substrate
• CPC Class Codes: B81B 7/0041 maintaining a controlled atmosphere with techniques not provided for in B81B7/0038
• CPC Class Codes: B81B 7/007 Interconnections between the MEMS and external electrical signals
• CPC Class Codes: B81B 7/0074 3D packaging, i.e. encapsulation containing one or several MEMS devices arranged in planes non-parallel to the mounting board
• CPC Class Codes: B81B 7/02 containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS] B81B7/04 takes precedence
• CPC Class Codes: H01L 2224/04042 Bonding areas specifically adapted for wire connectors, e.g. wirebond pads
• CPC Class Codes: H01L 2224/32145 the bodies being stacked
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48145 the bodies being stacked
• CPC Class Codes: H01L 25/16 the devices being of types provided for in two or more different main groups of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. forming hybrid circuits
• CPC Class Codes: H01L 25/50 Multistep manufacturing processes of assemblies consisting of devices, each device being of a type provided for in group H01L27/00 or H01L29/00 H01L21/50 takes precedence
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/10158 at the passive surface
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H01L 2924/1433 Application-specific integrated circuit [ASIC]
• CPC Class Codes: H01L 2924/1461 MEMS
• CPC Class Codes: H01L 2924/15311 being a ball array, e.g. BGA

Abstract

Methods for fabricating multi-sensor microelectronic packages and multi-sensor microelectronic packages are provided. In one embodiment, the method includes positioning a magnetometer wafer comprised of an array of non-singulated magnetometer die over an accelerometer wafer comprised of an array of non-singulated accelerometer die. The magnetometer wafer is bonded to the accelerometer wafer to produce a bonded wafer stack. The bonded wafer stack is then singulated to yield a plurality of multi-sensor microelectronic packages each including a singulated magnetometer die bonded to a singulated accelerometer die.

Claims

1. A method for fabricating multi-sensor microelectronic packages, the method comprising:

positioning a magnetometer wafer comprised of an array of non-singulated magnetometer die over an accelerometer wafer comprised of an array of non-singulated accelerometer die;

bonding the magnetometer wafer to the accelerometer wafer to produce a bonded wafer stack; and

singulating the bonded wafer stack to yield a plurality of multi-sensor microelectronic packages each including a singulated magnetometer die bonded to a singulated accelerometer die;

wherein the non-singulated magnetometer die and the non-singulated accelerometer die each have multiple sensing axes, and wherein the magnetometer wafer is rotationally aligned with the accelerometer wafer when positioned thereover such that the sensing axes of the non-singulated magnetometer die align with the sensing axes of the non-singulated accelerometer die.

2. The method of claim 1 wherein the magnetometer wafer is positioned over the accelerometer wafer such that the non-singulated magnetometer die are each positioned over a non-singulated accelerometer die.

3. The method of claim 2 wherein bonding comprises bonding the magnetometer wafer to the accelerometer wafer such that a hermetically-sealed cavity is created between each non-singulated magnetometer die and the underlying non-singulated accelerometer die.

4. The method of claim 3 wherein bonding comprises:

depositing rings of bonding material between the magnetometer wafer and the accelerometer wafer, each ring of bonding material circumscribing a Microelectromechanical Systems (MEMS) transducer structure formed on a non-singulated accelerometer die, as taken along an axis orthogonal to a surface of the accelerometer wafer; and

heating the bonding material to a predetermined temperature at a controlled pressure to bond the magnetometer wafer to the accelerometer wafer.

5. The method of claim 2 wherein the magnetometer wafer is bonded directly to the accelerometer wafer utilizing an electrically-conductive bonding material.

6. The method of claim 1 further comprising:

for each of the plurality of multi-sensor microelectronic packages, positioning the singulated magnetometer die and the singulated accelerometer die in proximity with a gyroscope die; and

interconnecting the singulated magnetometer die and the singulated accelerometer die with the gyroscope die.

9. The method of claim 1 further comprising thinning at least one of the magnetometer wafer and the accelerometer wafer prior to singulation of the bonded wafer stack.

10. The method of claim 9 wherein thinning comprises removing material from the backside of the accelerometer wafer to bring the accelerometer wafer to a desired thickness and to expose at least one through silicon via therethrough.

11. The method of claim 1 further comprising depositing an electrically-conductive material at selected locations between the magnetometer wafer on the accelerometer wafer to interconnect each non-singulated magnetometer die to the underlying non-singulated accelerometer die.

12. The method of claim 11 wherein the electrically-conductive material is further utilized to bond the magnetometer wafer to the accelerometer wafer to produce the bonded wafer stack.

13. The method of claim 1 wherein the magnetometer wafer has a frontside over which the array of non-singulated magnetometer die is formed, wherein the magnetometer wafer has a frontside over which the array of non-singulated accelerometer die is formed, and wherein the bonding comprises bonding the frontside of the magnetometer wafer to the frontside of the accelerometer wafer.

15. The method of claim 2 wherein the magnetometer wafer is bonded to the accelerometer wafer under elevated temperature and pressure conditions to impart each hermetically-sealed cavity with a first predetermined internal pressure upon cooling.

16. The method of claim 15 further comprising, after singulating the bonded wafer stack, bonding a gyroscope die to each singulated pair of magnetometer die and accelerometer die in a stacked configuration.

17. The method of claim 16 further comprising enclosing a transducer structure of each gyroscope die in a second hermetically-sealed cavity containing a second predetermined internal pressure less than the first predetermined internal pressure.

18. The method of claim 1 wherein a plurality of die stacks are produced pursuant to singulation of the bonded wafer stack, and wherein the method further comprises encapsulating each of the plurality of die stacks utilizing a Fan-Out Wafer Level Packaging (FO-WLP) process.

7. A method for fabricating multi-sensor microelectronic packages, the method comprising:

positioning a magnetometer wafer comprised of an array of non-singulated magnetometer die over an accelerometer wafer comprised of an array of non-singulated accelerometer die;

bonding the magnetometer wafer to the accelerometer wafer to produce a bonded wafer stack;

singulating the bonded wafer stack to yield a plurality of multi-sensor microelectronic packages each including a singulated magnetometer die bonded to a singulated accelerometer die;

after bonding the magnetometer wafer to the accelerometer wafer, removing portions of the non-singulated magnetometer die to reveal underlying regions of the non-singulated accelerometer die having bond pads thereon; and

producing wire bonds interconnecting the bond pads of the non-singulated accelerometer die with bond pads provided the non-singulated magnetometer die.

8. The method of claim 7 wherein the removing comprises cutting substantially parallel saw lanes in the bonded wafer stack to a depth substantially equivalent to the magnetometer wafer thickness.

19. The method of claim 7 wherein the non-singulated magnetometer die and the non-singulated accelerometer die each have multiple sensing axes, and wherein the magnetometer wafer is rotationally aligned with the accelerometer wafer when positioned thereover such that the sensing axes of the non-singulated magnetometer die align with the sensing axes of the non-singulated accelerometer die.

14. A method for fabricating multi-sensor microelectronic packages, the method comprising:

positioning a magnetometer wafer comprised of an array of non-singulated magnetometer die over an accelerometer wafer comprised of an array of non-singulated accelerometer die;

bonding the magnetometer wafer to the accelerometer wafer to produce a bonded wafer stack; and

singulating the bonded wafer stack to yield a plurality of multi-sensor microelectronic packages each including a singulated magnetometer die bonded to a singulated accelerometer die;

wherein the magnetometer wafer has backside and an opposing frontside over which the array of non-singulated magnetometer die is formed, wherein the magnetometer wafer has a frontside over which the array of non-singulated accelerometer die is formed, and wherein bonding comprises bonding the backside of the magnetometer wafer directly to the frontside of the accelerometer wafer.

20. The method of claim 14 wherein the non-singulated magnetometer die and the non-singulated accelerometer die each have multiple sensing axes, and wherein the magnetometer wafer is rotationally aligned with the accelerometer wafer when positioned thereover such that the sensing axes of the non-singulated magnetometer die align with the sensing axes of the non-singulated accelerometer die.