(19) United States
`
`(12) Patent Application Publication (10) Pub. No.: US 2010/0312468 A1
`Withanawasam
`(43) Pub. Date:
`Dec. 9, 2010
`
`US 20100312468A1
`
`(54)
`
`(75)
`
`INTEGRATED
`M[CRO-ELECTRO—MECHANICAL SYSTEMS
`(MEMS) SENSOR DEVICE
`
`Inventor:
`
`Lakshman Withanawasam. Maple
`(3’0"9- MN (US)
`dd
`d
`Correspon enceA ress:
`HONEYWELL/FOGG
`
`Patent Services
`101 Columbia Road, P-O Box 2245
`MOVI'IStOWfle NJ 07962-2245 (US)
`‘
`(73) Asmgnee:
`
`‘
`HONEYWELL
`INTERNATIONAL [RC-t
`MOYFISIOW NJ (US)
`
`(21) App]. No.:
`
`12/477,667
`
`(22)
`
`Filed:
`
`Jun. 3., 2009
`
`Publication Classification
`
`(51)
`
`Int Cl
`001C 21/00
`H01L 29/84
`H011. 21/50
`(52) us. Cl.
`
`(57)
`
`(2006.01)
`(2006.01)
`(2006.01)
`701/207; 257/415; 438/51; 257/1329324;
`257/E21.499
`
`,
`ABSTRACT
`
`An integrated sensor device is provided. The integrated sen-
`sor device comprises a first substrate including a surface
`portion and a second substrate coupled to the surface portion
`of the first substrate in a stacked configuration, wherein a
`cavity is defined between the first substrate and the second
`substrate. The integrated sensor device also comprises one or
`more micro-electromechanical systems (MEMS) sensors
`located at least partially in the first substrate. wherein the
`MEMS sensor communicates with the cavity. The integrated
`sensor device further comprises one or more additional sen-
`sors.
`
`(200"
`
`
`
`001
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`GOOGLE 1017
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`

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`Patent Application Publication
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`Dec. 9, 2010 Sheet 1 0f 5
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`US 2010/0312468 A1
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`PERSONAL NAVIGATION DEVICE (PN D)
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`m
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`PROCESSOR
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`m
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`DISPLAY
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`E
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`@
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`INTEGRAGED MEMS
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`AND MAGNETIC
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`SENSOR
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`@
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`NAVIGATION AND
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`ORIENTATION
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`ROUTINE
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`FIG. 1
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`002
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` _— §
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`g_%/////////////////////fl
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`FIG. 2A
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`003
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`OOOOOOOOOOOO
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`3]\_____
`xala\\\\
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`\
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`Patent Application Publication
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`Dec. 9, 2010 Sheet 4 0f 5
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`FIG. 2D
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`Patent Application Publication
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`Dec. 9, 2010 Sheet 5 0f 5
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`300 \
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`FORM AT LEAST A PORTION
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`OF A MEMS SENSOR
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`IN A FIRST SUBSTRATE
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`FORM AT LEAST ONE
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`ADDITIONAL SENSOR
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`PACKAGE THE SENSORS
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`BOND THE FIRST SUBSTRATE
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`TO A SECOND SUBSTRATE
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`IN A STACKED CONFIGURATION
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`FIG. 3
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`006
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`US 2010/0312468A1
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`Dec. 9, 2010
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`INTEGRATED
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`MICRO-ELECTRO-MECHANICAL SYSTEMS
`
`
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`
`
`(MEMS) SENSOR DEVICE
`
`BACKGROUND
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`[0001] Mobile devices such as personal navigation devices
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`(PND) and smart phones typically have some form of navi-
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`gation and map orientation application. These mobile devices
`often utilize a magnetic compass that have to work even when
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`the device is not held level, which requires a micro-electro-
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`mechanical systems (MEMS) accelerometer or a gyroscope
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`to be integratedwith the magnetic sensors. The typical mobile
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`device includes a magnetic compass sensor as well as a sepa-
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`rate MEMS accelerometer or a gyroscope sensor. However,
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`including these sensors as two separate sensor devices in a
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`mobile device takes a large printed circuit board (PCB) foot-
`print. Because the mobile navigation devices are very sensi-
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`tive to cost and size, any solution that reduces cost or the
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`printed circuit board (PCB) footprint of the compass hard-
`ware is desired.
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`SUMMARY
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`[0002] One embodiment of the present invention provides
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`an integrated sensor device. The integrated sensor device
`comprises a first substrate including a surface portion and a
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`second substrate coupled to the surface portion of the first
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`substrate in a stacked configuration, wherein a cavity is
`defined between the first substrate and the second substrate.
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`The integrated sensor device also comprises one or more
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`micro-electro-mechanical systems (MEMS) sensors located
`at least partially in the first substrate, wherein the MEMS
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`sensor communicates with the cavity. The integrated sensor
`device further comprises one or more additional sensors.
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`DRAWINGS
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`Features ofthe present invention will become appar-
`[0003]
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`ent to those skilled in the art from the following description
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`with reference to the drawings. Understanding that the draw-
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`ings depict only typical embodiments ofthe invention and are
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`not therefore to be considered limiting in scope, the invention
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`will be described with additional specificity and detail
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`through the use of the accompanying drawings, in which:
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`FIG. 1 is one embodiment of a personal navigation
`[0004]
`device (PND) comprising an integrated MEMS and magnetic
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`sensor;
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`FIGS. 2A-2C are cross-sectional side views of alter-
`[0005]
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`native embodiments of a stacked MEMS sensor device;
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`[0006]
`FIG. 2D is top view of the stacked MEMS sensor
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`device of FIG. 2A; and
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`[0007]
`FIG. 3 is a flowchart of one embodiment of a method
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`of forming an integrated MEMS sensor device.
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`DETAILED DESCRIPTION
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`In the following detailed description, embodiments
`[0008]
`are described in sufficient detail to enable those skilled in the
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`art to practice the invention. It is to be understood that other
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`embodiments may be utilized without departing from the
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`scope of the present
`invention. The following detailed
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`description is, therefore, not to be taken as limiting.
`[0009] The embodiments described hereafter relate to inte-
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`grated micro-electro-mechanical systems (MEMS) sensor
`devices that include a MEMS sensor and at least one addi-
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`tional sensor, such as a magnetic sensor. Typically, MEMS
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`sensors are capped with a substrate to create a cavity needed
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`for the accelerometer to fiinction and are encompassed in
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`plastic molded packages. Portions of the MEMS substrate
`and the cap substrate are often left unused. In one embodi-
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`ment ofthe present invention, a MEMS sensor and a magnetic
`sensor are integrated into a single stacked configuration. In
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`one implementation, the electrically unused (blank) semicon-
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`ductor area of a cap of a MEMS sensor is utilized to host one
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`or more additional sensors in a stacked configuration to form
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`an integrated sensor device.
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`[0010] The present integrated MEMS sensor devices are
`miniature sensor devices that reduce the amount of semicon-
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`ductor substrate material used in the device and concurrently
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`reduce the PCB footprint of the packaged device. Integrating
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`an accelerometer (also referred to herein as a tilt sensor) or a
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`gyroscope and magnetic sensors into a common semiconduc-
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`tor device reduces the size taken up by the sensors compared
`to when the sensors are formed in individual semiconductor
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`Chips. For example, a magnetic sensor die and a tilt sensor die
`can be stacked together to reduce the package size and
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`thereby the package footprint. Since the already available
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`substrate area is used more fully in the present embodiments,
`fabrication costs will also be lower.
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`FIG. 1 is one embodiment of a personal navigation
`[0011]
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`device (PND) 100 comprising an integrated MEMS and mag-
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`netic sensor 130. The PND 100 can be a mobile (hand-held)
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`navigation device, a smart phone, or any similar mobile
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`device configured to aid a user in navigation and applications
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`requiring orientation information. For example, a user can be
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`a professional first responder or a member of the public. The
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`PND 100 includes a processor 110 configured to run a navi-
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`gation and orientation routine module 120. A display 140
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`presents navigation information to the user, and can comprise
`a liquid crystal display (LCD), a digital display, or the like.
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`Navigation information that can be displayed includes posi-
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`tional information, orientation information, maps, compass
`directions, a predetermined path, or any other information
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`useful in navigation.
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`[0012] Orientation information is information relating to
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`the present orientation of the PND 100, and can be deter-
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`mined using the integrated MEMS and magnetic sensor 130
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`(also referred to herein as the integrated MEMS sensor). The
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`integrated MEMS and magnetic sensor 130 provides infor-
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`mation to the processor 110 relating to acceleration, roll, and
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`directional data (that is, relating to a compass direction). The
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`PND 100 can use three axes of sensing for acceleration and
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`gyroscope data in one single integrated MEMS sensor 130. In
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`alternative embodiments, the PND 100 comprises a plurality
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`of integrated MEMS sensors 130, each for a different axis of
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`acceleration or gyroscope data. The components of the PND
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`100 are communicatively coupled to one another as needed
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`using suitable interfaces and interconnects.
`[0013]
`FIGS. 2A-2C illustrate alternative embodiments of
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`a stacked sensor device 200, 200', and 200". The integrated
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`MEMS sensor devices 200, 200‘, and 200" comprise a first
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`substrate 210 including a surface portion 212. The first sub-
`strate 210 contains at least one MEMS sensor 220. A second
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`substrate 240 is coupled to surface portion 212 of the first
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`substrate 210. In some embodiments, portions of the MEMS
`sensor 220 are located in the second substrate 240. The sensor
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`devices 200, 200', and 200" comprise at least one additional
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`sensor 250 such as a magnetic sensor.
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`[0014] The first and second substrates 210, 240 can be
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`composed of various materials such as silicon, glass, quartz,
`
`007
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`007
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`

`

`
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`US 2010/0312468 Al
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`Dec. 9, 2010
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`or the like. In one embodiment, the second substrate 240 is a
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`cap used to cover the MEMS sensor 220. The cap can be
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`sealingly attached to surface portion 212 of substrate 210
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`using a known bonding process such as glass fritz bonding,
`gluing, or welding.
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`[0015] The MEMS sensor 220 can include one or more
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`accelerometers, gyroscopes, or combinations thereof, as well
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`as flow sensors, gas detectors, or any other sensor suitable for
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`MEMS technology that has an electrically unused portion in
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`at least one of the substrate 210 or the cap 240. For example,
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`three accelerometer axes can be employed in a single sensor
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`device 200. Similarly, two gyroscope axes canbe employed in
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`a single sensor device 200. In one embodiment, the MEMS
`sensor 220 includes a tilt sensor die.
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`[0016] The integrated sensor devices 200, 200', and 200"
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`further comprise a cavity 230, which is formed between the
`first substrate 210 and the second substrate 240. The second
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`sujstrate 240 acts as a cap that protects the MEMS sensor 220
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`from the external environment and seals the cavity 230. The
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`MEMS sensor 220 is in communication with the cavity 230.
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`As shown in FIGS. 2A-2C the cavity 230 is formed through
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`the surface portion 212 of the substrate 210. However, in
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`alternative embodiments, the cavity 23 0 is formed in a bottom
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`aortion 242 of the second substrate 240. The cavity 230 is
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`sealed to hold either a vacuum or an inert gas. The cavity 230
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`‘s used to provide freedom ofmovement to the MEMS sensor
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`220, enabling movements such as vibration and rotation.
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`[0017] The second substrate 240 (that is, the cap) comprises
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`he bottom portion 242 and a top portion 244. In MEMS
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`devices, the cap (and parts of the first substrate 210) typically
`'ncludes electrically unused (that is, blank) portions on the
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`op portion244. A blankportion ofa substrate any portion that
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`illustrates an embodiment where the one or more sensors 250
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`are located in the second substrate 240. This embodiment of
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`he sensor device 200 provides that part or all of the electri-
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`cally unused portion of the top portion 244 host one or more
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`sensors 250. The sensors 250 can include a magnetic sensor,
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`a pressure sensor, a temperature sensor, or any type of suitable
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`electronic circuitry. In alternative embodiments, the cap fur-
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`her comprises active MEMS sensor elements or forms part of
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`the overall integrated MEMS sensor device 200. FIG. 2D is a
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`op view ofthe stacked MEMS sensor device 200 of FIG. 2A,
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`oortion 244 of the second substrate 240.
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`[0018] As shown in the embodiment of FIG. 2B, one or
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`nore additional sensors 250 are located in electrically unused
`aortions ofthe first substrate 210 of the MEMS sensor device
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`200'. As depicted in the embodiment of FIG. 2C, one or more
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`additional sensors 250 are located in electrically unused por-
`ions ofthe first substrate 210 and the second substrate 240 of
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`he MEMS sensor device 200".
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`[0019]
`In the embodiment of FIGS. 2A-2D, the MEMS
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`sensor 220 and the sensors 250 are electrically isolated. In
`alternative embodiments, the MEMS sensor 220 and the sen-
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`sors 250 are not electrically isolated. Leads from each sensor
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`may extend out of their respective substrates. Embodiments
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`of the sensor devices 200, 200', and 200" also comprise a
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`metal or substrate frame (not shown) that enables outputs
`from the sensors 220 and 250 to be connected to other devices
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`(for example, via wires or leads). The sensor devices 200,
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`200', and 200" also comprise packaging (such as plastic
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`molded packages) for assembly to a next level of a device
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`(such as in the PND 100). Packaging makes the sensor
`devices 200, 200', and 200" easier to handle and more robust.
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`FIG. 3 is a flowchart of one embodiment ofa method
`[0020]
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`300 of integrating a sensor with a MEMS device. At least a
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`portion of a MEMS sensor is formed in a first substrate (310).
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`If the MEMS sensor is not formed entirely in the first sub-
`strate, the rest is formed in a second substrate. One exemplary
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`method of fabricating a MEMS active wafer is the Micragem
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`standard. The Micragem standard comprises first etching
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`cavities in a glass wafer. Then electrodes, lines, and bond pads
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`are patterned. A silicon on insulator (SOI) handle wafer is
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`anodically bonded to the glass wafer. The silicon handle
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`wafer and a buried oxide layer are etched. Next, a low stress
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`metal is deposited. Lithographically pattern and deep reactive
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`ion etch (DRIE) is performed to release silicon microstruc-
`tures. The MEMS sensor elements are formed. However, the
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`Micragem standard is just one exemplary method, and other
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`suitable methods of forming a MEMS sensor known to those
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`of skill in the art are contemplated.
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`[0021] Once the MEMS sensor is formed (310), one or
`more sensors or electrical circuits are formed. These addi-
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`tional sensors can be fabricated on or in the blank portions of
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`the first substrate, a second substrate (for example, the MEMS
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`cap wafer), or combinations thereof (320). The method of
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`fabricating the sensors onto the cap wafer will depend on the
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`particular sensor being made. For an exemplary process of
`fabricating magnetic sensors for providing compass data, see
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`US. Pat. No. 5,820,924, filed on Jun. 6, 1997, entitled
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`“Method of Fabricating a Magnetoresistive Sensor,” which is
`incorporated by reference herein.
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`[0022] Once all the sensors are fabricated, the second sub-
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`strate (cap wafer) is bonded to the first substrate using exist-
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`ing mechanical processes (330). This creates the integrated
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`MEMS and sensor stack, which is then packaged to yield the
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`miniature sensor device (340).
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`In one embodiment, a single device package com-
`[0023]
`prises integrated magnetic and tilt sensors. The electrically
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`unused silicon surface of a tilt sensor die is used as a magnetic
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`sensor die. The magnetic sensor die and the tilt sensor die are
`stacked together to reduce the package size and thereby the
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`footprint of the device. Since the silicon area is reused, the
`cost and the footprint both will be reduced. This combined tilt
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`sensor and magnetic sensor can be used to provide position
`and orientation data in a PND.
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`[0024] The present invention may be embodied in other
`specific forms without departing from its essential character-
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`istics. Aspects and limitations described in a specific embodi-
`ment are combinable with other embodiments. The described
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`embodiments are to be considered in all respects only as
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`illustrative and not restrictive. The scope of the invention is
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`therefore indicated by the appended claims rather than by the
`foregoing description. All changes that come within the
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`meaning and range of equivalency of the claims are to be
`embraced within their scope.
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`What is claimed is:
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`1. An integrated sensor device, comprising:
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`a first substrate including a surface portion;
`a second substrate coupled to the surface portion ofthe first
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`substrate in a stacked configuration, wherein a cavity is
`defined between the first substrate and the second sub-
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`strate;
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`008
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`008
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`

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`US 2010/0312468 Al
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`Dec. 9, 2010
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`12. The method of claim 9, wherein the MEMS sensor
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`comprises an accelerometer, a gyroscope, or combinations
`thereof.
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`13. The method of claim 9, wherein the at least one addi-
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`tional sensor comprises a magnetic sensor.
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`14. The method of claim 9, wherein the cavity contains a
`vacuum or an inert gas.
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`15. A navigation device, comprising:
`an integrated sensor device, comprising:
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`a first substrate including a surface portion;
`a second substrate coupled to the surface portion of the
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`first substrate in a stacked configuration, wherein a
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`cavity is defined between the first substrate and the
`second substrate;
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`systems
`or more micro-electro-mechanical
`one
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`(MEMS) sensors located at least partially in the first
`substrate, wherein the one or more MEMS sensors
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`communicates with the cavity; and
`one or more additional sensors;
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`a processor operatively coupled to the integrated sensor
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`device; and
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`a navigation module run by the processor, wherein the
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`navigation module is configured to determine orienta-
`tion information based on data from the integrated sen-
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`sor device.
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`16. The navigation device of claim 15, further comprising
`a display configured to present the positional information to a
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`user.
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`17. The navigation device of claim 15, wherein the navi-
`gation device comprises a personal navigation device (PND)
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`or a smart phone.
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`18. The navigation device of claim 15, wherein the one or
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`more MEMS sensors comprise an accelerometer, a gyro-
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`scope, a flow sensor, a gas detector, or combinations thereof.
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`19. The navigation device of claim 15, wherein the one or
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`more additional sensors comprise a magnetic sensor, a pres-
`sure sensor, or combinations thereof.
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`20. The navigation device of claim 15, wherein the one or
`more additional sensors are formed in the first substrate, the
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`second substrate, or combinations thereof.
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`*
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`>l=
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`one or more micro-electro-mechanical systems (MEMS)
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`sensors located at least partially in the first substrate,
`wherein the MEMS sensor communicates with the cav-
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`ity; and
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`one or more additional sensors.
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`2. The sensor device of claim 1, wherein the first substrate
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`and the second substrate comprise silicon, glass, or quartz.
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`3. The sensor device ofclaim 1, wherein the cavity contains
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`a vacuum or an inert gas.
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`4. The sensor device of claim 1, wherein the one or more
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`MEMS sensors comprise an accelerometer, a gyroscope, a
`flow sensor, a gas detector, or combinations thereof.
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`5. The sensor device of claim 1, wherein the one or more
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`additional sensors comprise a magnetic sensor, a pressure
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`sensor, or combinations thereof.
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`6. The sensor device of claim 1, wherein:
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`the one or more MEMS sensors is configured to provide
`acceleration data; and
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`the one or more additional sensors is at least one magnetic
`sensor configured to provide directional data.
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`7. The sensor device of claim 1, wherein the one or more
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`MEMS sensors and the one or more additional sensors are
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`electrically isolated from each other.
`8. The sensor device of claim 1, wherein the one or more
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`additional sensors are located in the first substrate, the second
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`substrate, or combinations thereof.
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`9. A method of forming an integrated sensor device, the
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`method comprising:
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`forming at least a portion of a micro-electro-mechanical
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`systems (MEMS) sensor in a first substrate;
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`forming at least one additional sensor; and
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`bonding the first substrate to the second substrate in a
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`stacked configuration, wherein a cavity is defined
`between the first substrate and the second substrate, and
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`the MEMS sensor communicates with the cavity.
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`10. The method of claim 9, further comprising packaging
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`the first substrate and the second substrate.
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`11. The method of claim 9, wherein forming at least one
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`additional sensor further comprises forming the at least one
`additional sensor in the first substrate, the second substrate, or
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`combinations thereof
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`009
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`009
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`