# Patent

## Title
Multi-die MEMS package

## Abstract

This document refers to multi-die micromechanical system (MEMS) packages. In an example, a multi-die MEMS package can include a controller integrated circuit (IC) configured to couple to a circuit board, a MEMS IC mounted to a first side of the controller IC, a through silicon via extending through the controller IC between the first side and a second side of the controller IC, the second side opposite the first side, and wherein the MEMS IC is coupled to the through silicon via.

## Background
CLAIM OF PRIORITY
This application is a divisional of U.S. patent application Ser. No. 13/821,609, filed on May 20, 2013, which is a U.S. National Stage Filing under 35 U.S.C. 371 from International Patent Application Serial No. PCT/US2011/051994 filed on Sep. 16, 2011, and published on Mar. 22, 2012 as WO 2012/037492 A2 and republished on Jun. 7, 2012 as WO 2012/037492 A3, which claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 61/384,241, entitled “Multi-Die Packaging of MEMS with Through Silicon Vias”, filed Sep. 18, 2010, (Attorney Docket No.: 2921.096PRV), and also to U.S. Provisional Patent Application Ser. No. 61/384,321, entitled, “Integrated Inertial Sensor”, filed Sep. 20, 2010, (Attorney Docket No.: 2921.0105PRV), which each are hereby incorporated by reference herein in their entirety.


BACKGROUND
Generally, applications using multiple microelectromechanical system (MEMS) chips include a separate controller for each MEMS chip. For example, an inertial sensor can be packaged with its own application specific integrated circuit (ASIC) while a pressure sensor is packaged with a separate ASIC. Because each additional MEMS chip includes an associated controller or controller circuitry, multiple MEMS systems can multiply the amount of power consumed, silicon and silicon real estate used, engineering resources used, and costs expended to produce the system. Additionally, some MEMS chips require high voltage signals. High voltage ASICs can be manufactured, but are expensive and not fully standardized. A MEMS requiring high voltage is stuck using an expensive ASIC, increasing the cost to levels that are not able support many consumer applications.
OVERVIEW
This document refers to multi-die micromechanical system (MEMS) packages. In an example, a multi-die MEMS package can include a controller integrated circuit (IC) configured to couple to a circuit board, a MEMS IC mounted to a first side of the controller IC, a through silicon via extending through the controller IC between the first side and a second side of the controller IC, the second side opposite the first side, and wherein the MEMS IC is coupled to the through silicon via.
This overview is intended to provide an overview of subject matter of the present patent application. It is not intended to provide an exclusive or exhaustive explanation of the invention. The detailed description is included to provide further information about the present patent application.



BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.
FIGS. 1-4 illustrate generally examples of multi-die MEMS packages.



DETAILED DESCRIPTION
FIG. 1 illustrates generally an example multi-die MEMS package 100 including a MEMS device 101 and a controller integrated circuit (IC) 102, such as an application-specific IC (ASIC). In certain examples, the MEMS device 101 is coupled to contacts on one side of the controller IC 102 and the controller IC 102 includes through silicon vias (TSVs) to couple the contacts to second contacts on the other side of the controller IC 102. The TSVs can eliminate wire bonds, and the area that accommodates the wire bonds, extending from the MEMS device 101 to the controller IC 102 or other circuitry, such as a printed circuit board (PCB) 103. In certain examples, the multi-die MEMS package 100 can reduce the package footprint of the overall device.
In certain examples, the multi-die MEMS package 100 can include a high voltage chip 104 mounted on top of the controller IC 102 proximate the MEMS device 101. In such an example, the high voltage chip 104 can provide the high voltage circuitry of the multi-die MEMS package 100 and the controller IC 102 can provide the low voltage circuitry of the multi-die MEMS package 100. In an example, multiple MEMS devices 101 can be mounted on top of, and coupled to, the controller IC 102, or to other circuitry, using through silicon vias (TSVs) of the controller IC 102.
FIG. 2 illustrates an example of a multi-die MEMS package 200 including a MEMS device 201 and a controller IC 202 that includes TSVs 204. The MEMS device can include a device layer 205 and a cap layer 206. In an example, the device layer 205 can include a proof mass 207 supported by one or more an anchors 208. In an example, the device layer can include a proof mass supported by a single anchor. In certain examples, a MEMS IC can include more than one proof mass 207 within the device layer 205. The device layer 205, including the proof mass 207, can include gaps 209 extending in both vertical and horizontal directions through the device layer 205. The gaps 209 can form multiple moveable portions of a proof mass 207 and can allow in-plane movement and out-of-plane movement of the multiple portions, with respect to a major surface of the device layer 205. In an example, the in-plane movement and the out-of-plane movement of the proof mass 207 can be used to sense acceleration and rotation of the multi-die MEMS package 200. In certain examples, the device layer 205 can be etched to provide an inertial sensor with six degrees of freedom for sensing linear and angular acceleration of the MEMS package 200. In certain examples, the cap layer 206 can provide a portion of an environmental enclosure for the proof mass 207. In an example, a cavity 210 within the cap layer 206, or the device layer 205, can provide an area within which the proof mass 207 can move in the out-of-plane direction. In an example, the cap layer 206 can restrict out-of-plane movement of the proof mass 207, such as when the multi-die MEMS package 200 encounters a mechanical shock. In certain examples, the environmental enclosure housing the device layer 205 can maintain a vacuum about the moveable portions of the device layer 205.
In certain examples, the device layer 205 is bonded to a controller IC 202 such as an ASIC. In an example, the device layer 205, in cooperation with electrodes formed in the controller IC 202, such as electrodes formed in a passivation layer of the controller IC 202, can include differentials sensors for each axis of out-of-plane movement of the proof mass 207. In certain examples, the controller IC 202 can include one or more through silicon vias (TSVs) 204 to electrically couple signals from one side of the controller IC 202 to a different side of the controller IC 202. For example, the controller IC 202 can include a TSV 204 to couple an electrode of the MEMS device 201 located to one side of the controller IC 202 to a contact 211 located on the opposite side of the controller IC 202. In certain examples, the controller IC 202 can include a device layer 212. The device layer 212 can include integrated electronic circuitry, such as transistors, to process information related to the MEMS device 201. In an example, the device layer 212 of the controller IC 202 can provide control circuitry more than one MEMS device 201 mounted to the controller IC 202. In an example, the controller IC 202 can include a passivation layer 213 to protect the device layer 212. In certain examples, the passivation layer 213 can be used to form electrodes for the MEMS device 201.
In certain examples, a wafer bond metal 214 can couple a perimeter bond area of the device layer 205 to the controller IC 202. In an example, the wafer bond metal 214 can couple the single anchor 208 to the controller IC 202. In an example, the wafer bond metal 214 can couple the device layer 205, including the single anchor 208, directly to raw silicon of the controller IC 202. In an example, using a uniform bonding layer to bond the perimeter area of the device layer 205 and the anchor 208, and the ability to provide differential out-of-plane sensing, can result in improved rejection of thermal expansion effects and can reduce stress gradients of the bonded components. Improved rejection of thermal expansion effects and reduced stress gradients of the bonded components can both improve performance of the MEMS device 201.
In certain examples, the controller IC can include interconnects 218 to couple the multi-die MEMS package to other circuitry. In an example, the interconnects 218 can include solder bumps.
FIG. 3 illustrates generally an example multi-die MEMS package 300 including a MEMS device 301 and a controller IC 302 with through silicon vias (TSVs). The MEMS device 301 can include a device layer 305, a cap layer 306 and a via layer 315. In an example, the device layer 305 can include a MEMS structure including a proof mass 307 and a single anchor 308 configured to support the proof mass 307. In an example, the cap layer 306 and the via layer 315 can provide an environmental enclosure for the MEMS structure. In an example, the cap layer 306 and the via layer 315 can provide a stiff mechanical support for the MEMS structure such that components of the MEMS structure can be isolated from packaging stresses. In an example, the MEMS structure can be an inertial sensor structure. In an example, the MEMS structure can be a gyroscope sensor. In an example, the MEMS structure can be an accelerometer sensor. In certain examples, the MEMS structure can include one or more multi-axis, inertial sensors, such as, but not limited to, a 3-axis gyroscope, 3-axis accelerometer, or an integrated, multi-axis, gyroscope and accelerometer. In certain examples, the via layer 315 can include electrically isolated regions that provide electrodes for the MEMS structure and routing circuitry to couple the MEMS device to the controller IC 302, such as an
ASIC. In certain examples, solder joints 316 between the via layer 315 and the controller IC 302 can be located at or near the outer edges of the via layer 315 such as near the perimeter of the via layer 315. Locating the solder joints 316 at the perimeter of the via layer 315 can reduce the influence of stress introduced when the controller IC 302 is mounted to other circuitry such as a printed circuit board (PCB) 303.
In an example, the controller IC 302 can include a redistribution layer 317, including conductive materials, to couple the controller IC 302, as well as the multi-die MEMS package 300, to other circuitry, such as the printed circuit board (PCB) 303. In an example, the redistribution layer 317 can include interconnects 318, such as for soldering to the PCB 303. The interconnects 318 can be clustered near the center of the controller IC 302 to reduce packaging stress communicated to the MEMS device 301 coupled to the controller IC 302. In certain examples, such as where a controller IC 302 supports more than one MEMS device, the interconnects can be clustered about the center of each footprint defined by the MEMS devices overlying the controller IC 302. In certain examples, interconnects for coupling the controller IC 302 of a multi-die MEMS package 300 can include polymer-core copper interconnects to further reduce packaging stress. In an example, the controller IC 302 and the PCB 303 can include a low stiffness boundary layer (SBL) to reduce stress introduced when the multi-die MEMS package 300 is electrically coupled to the PCB 303.
FIG. 4 illustrates generally a portion of an example system 400 including multiple MEMS devices 401, 421. In certain examples, the system 400 includes a MEMS package 420 mounted on a PCB 403. The MEMS package 420 can include a controller IC 402 such as an ASIC. The MEMS package 420 can include multiple MEMS devices 401, 421 mounted to the controller IC 402. Mounting multiple MEMS devices 401, 421 to a single controller IC 402 can save space otherwise used by a separate controller IC for each MEMS device. In an example, the MEMS package 420 can include a high voltage controller IC 404 that can provide a higher voltage to those MEMS devices of the system 400 that use a higher voltage than the technology used for the controller IC 402. In certain examples, a high voltage IC 404, such as a high voltage ASIC, can be used to drive a proof mass of a MEMS device layer to oscillate at a resonant frequency. Such movement of a MEMS structure can assist in detecting angular acceleration of the multi-die MEMS package 420. Such a configuration saves costs and footprint area associated with fabricating the entire controller IC using high voltage technology. In certain examples, the MEMS devices 401, 421 can include inertial sensors such as gyroscope sensors, and acceleration sensors, pressure sensors, compass sensors, etc. It is understood that a system can include additional MEMS sensors, as well as other devices, mounted to the controller IC 402 where the controller IC includes sufficient space and processing capabilities.
Additional Notes and Examples
In Example 1, an apparatus can include a controller integrated circuit (IC) configured to couple to a circuit board, a microelectromechanical system (MEMS) IC mounted to a first side of the controller IC, a through silicon via extending through the controller IC between the first side and a second side of the controller IC, the second side opposite the first side, and wherein the MEMS IC is coupled to the through silicon via.
In Example 2, the apparatus of Example 1 optionally includes a plurality of solder interconnects coupled to the circuit board and the control IC.
In Example 3, the MEMS IC of any one or more of Examples 1-2 optionally includes an inertial sensor.
In Example 4, the inertial sensor of any one or more of Examples 1-3 optionally includes an inertial sensor having six degrees of freedom.
In Example 5, the MEMS IC of any one or more of Examples 1-4 optionally includes a device layer having multiple moveable portions and a single anchor, the device layer configured to allow in-plane movement and out-of-plane movement of one or more of the moveable portions, and the single anchor configured to support the multiple moveable portions, and a cap layer couple to the device layer opposite the controller IC.
In Example 6, the inertial sensor of any one or more of Examples 1-5 optionally includes a via layer coupled to the device layer at a perimeter of the device layer and at the anchor, the via layer including electrically isolated regions configured to provide out-of-plane electrodes of the inertial sensor.
In Example 7, the device layer of any one or more of Examples 1-6 is optionally coupled directly to the controller IC at a perimeter of the device layer and at the single anchor.
In Example 8, the control IC of any one or more of Examples 1-7 optionally includes an application specific IC (ASIC).
In Example 9, the apparatus of any one or more of Examples 1-8 optionally includes a high voltage control IC configured to supply voltage to drive the MEMS IC into resonance.
In Example 10, the high voltage control IC of any one or more of Examples 1-9 is optionally mounted to the control IC.
In Example 11, the control IC of any one or more of Examples 1-10 optionally includes a first application specific IC (ASIC), and the high voltage control IC of any one or more of Examples 1-10 optionally includes a second ASIC.
In Example 12, an apparatus can include a microelectromechanical system (MEMS) integrated circuit (IC) and a controller IC. The MEMS IC can include a device layer having a plurality of gaps, the plurality of gaps forming multiple moveable portions and a single anchor, the single anchor configured to support the multiple moveable portions, and a cap layer coupled to the device layer and configured to maintain a vacuum about the multiple moveable portions and to limit out-of-plane movement of the multiple moveable portions. The controller IC have a first side coupled to the MEMS IC, and the controller IC can include a through silicon via extending through the controller IC from the first side to a second side of the controller IC. The through silicon via can be configured to electrically couple contacts located the first side of the controller IC with contacts located on the second side of the controller IC.
In Example 13, the MEMS IC of any one or more of Examples 1-12 optionally includes a via wafer coupled to the device layer opposite the cap layer, the via layer configured to electrically couple the device layer and the controller IC.
In Example 14, the controller IC of any one or more of Examples 1-13 is optionally directly coupled to the device layer at a perimeter of the device layer and at the single anchor.
In Example 15, the MEMS IC of any one or more of Examples 1-14 optionally includes an inertial sensor.
In Example 16, the MEMS IC of any one or more of Examples 1-15 optionally includes a three axis gyroscope sensor and a three axis accelerometer.
In Example 17, the three axis gyroscope sensor of any one or more of Examples 1-16 and the three axis accelerometer of any one or more of Examples 1-16 are optionally mechanically integrated within the device layer.
In Example 18, the apparatus of any one or more of Examples 1-17 optionally includes a MEMS pressure sensor IC coupled to the first side of the controller IC.
In Example 19, the apparatus of any one or more of Examples 1-18 is optionally includes a high voltage controller IC coupled to the first side of the controller IC proximate the MEMS IC, the high voltage controller IC configured to operate with higher voltages than the controller IC.
In Example 20, the controller IC of any one or more of Examples 1-19 is optionally includes an application-specific IC (ASIC).
Example 21 can include, or can optionally be combined with any portion or combination of any portions of any one or more of Examples 1-20 to include, subject matter that can include means for performing any one or more of the functions of Examples 1-20, or a machine-readable medium including instructions that, when performed by a machine, cause the machine to perform any one or more of the functions of Examples 1-20.
The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as “examples.” All publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference(s) should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.
In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.
The above description is intended to be illustrative, and not restrictive. In other examples, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. The
Abstract is provided to comply with 37 C.F.R. §1.72(b), to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

## Claims

1. An apparatus comprising:
a controller integrated circuit (IC) configured to couple to a circuit board;
a via layer mounted to a first side of the controller IC;
a device layer having multiple moveable portions and a single anchor, the device layer configured to allow in-plane movement and out-of-plane movement of one or more of the moveable portions, and the single anchor configured to support the multiple moveable portions; and
wherein the via layer is coupled to the device layer at a perimeter of the device layer and at the anchor, the via layer including electrically isolated regions configured to provide electrodes for out-of-plane movement of one or more of the multiple moveable portions.

2. The apparatus of claim 1, including a plurality of solder interconnects coupled to the circuit board and the control IC.

3. The apparatus of claim 1, wherein the apparatus includes an inertial sensor.

4. The apparatus of claim 3, wherein the inertial sensor includes an inertial sensor having six degrees of freedom.

5. The apparatus of claim 1, including
a cap layer couple to the device layer opposite the controller IC.

6. The apparatus of claim 5, wherein the device layer is coupled directly to the controller IC at a perimeter of the device layer and at the single anchor.

7. The apparatus of claim 1, wherein the controller IC includes an application specific IC (ASIC).

8. The apparatus of claim 1, including a high voltage controller IC configured to supply voltage to drive the device layer into resonance.

9. The apparatus of claim 8, wherein the high voltage controller IC is mounted to the controller IC.

10. The apparatus of claim 8, wherein the controller IC includes a first application specific IC (ASIC); and
wherein the high voltage controller IC includes a second ASIC.

11. An apparatus comprising:
a controller integrated circuit (IC) configured to couple to a circuit board;
a microelectromechanical system (MEMS) IC mounted to a first side of the controller IC;
a through silicon via extending through the controller IC between the first side and a second side of the controller IC, the second side opposite the first side;
wherein the MEMS IC is coupled to the through silicon via; and
a high voltage controller IC configured to supply voltage to drive the MEMS IC into resonance.

12. The apparatus of claim 8, wherein the high voltage controller IC is mounted to the controller IC.

13. The apparatus of claim 8, wherein the controller IC includes a first application specific IC (ASIC); and
wherein the high voltage controller IC includes a second ASIC.

14. The apparatus of claim 11, wherein the MEMS IC includes an inertial sensor.

15. The apparatus of claim 14, wherein the inertial sensor includes an inertial sensor having six degrees of freedom.

16. The apparatus of claim 11, wherein the MEMS IC includes:
a device layer having multiple moveable portions and a single anchor, the device layer configured to allow in-plane movement and out-of-plane movement of one or more of the moveable portions, and the single anchor configured to support the multiple moveable portions; and
a cap layer couple to the device layer opposite the controller IC.

17. The apparatus of claim 16, wherein the inertial sensor includes a via layer coupled to the device layer at a perimeter of the device layer and at the anchor, the via layer including electrically isolated regions configured to provide out-of-plane electrodes of the inertial sensor.

18. The apparatus of claim 16, wherein the device layer is coupled directly to the controller IC at a perimeter of the device layer and at the single anchor.

19. The apparatus of claim 11, wherein the controller IC includes an application specific IC (ASIC).