U.S. patent application number 14/596985 was filed with the patent office on 2015-12-31 for pressure sensor and manufacture method thereof.
The applicant listed for this patent is MiraMEMS Sensing Technology Co., Ltd.. Invention is credited to Yu-Hao CHIEN, Li-Tien TSENG.
Application Number | 20150375988 14/596985 |
Document ID | / |
Family ID | 54929730 |
Filed Date | 2015-12-31 |
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United States Patent
Application |
20150375988 |
Kind Code |
A1 |
CHIEN; Yu-Hao ; et
al. |
December 31, 2015 |
PRESSURE SENSOR AND MANUFACTURE METHOD THEREOF
Abstract
A pressure sensor using the MEMS element and the manufacture
method thereof utilize the semiconductor processes to form the
micro channel connecting to the chamber, open the micro channel,
coat the anti-sticking layer on the inner surface of the chamber,
and then seal the micro channel to keep the chamber airtight.
Therefore, the manufacture method may essentially simplify the
process to coat the anti-sticking layer on the inner surface of the
airtight chamber to prevent the sticking and failing of the movable
MEMS element.
Inventors: |
CHIEN; Yu-Hao; (Taipei City,
TW) ; TSENG; Li-Tien; (Taoyuan County, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MiraMEMS Sensing Technology Co., Ltd. |
Suzhou |
|
CN |
|
|
Family ID: |
54929730 |
Appl. No.: |
14/596985 |
Filed: |
January 14, 2015 |
Current U.S.
Class: |
257/417 ;
438/51 |
Current CPC
Class: |
B81B 2201/0264 20130101;
B81B 3/0005 20130101 |
International
Class: |
B81B 3/00 20060101
B81B003/00; B81C 1/00 20060101 B81C001/00; B81B 7/00 20060101
B81B007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 25, 2014 |
TW |
103121912 |
Claims
1. A manufacture method of a pressure sensor, comprising: providing
a first substrate comprising a metal layer, wherein the metal layer
is partially exposed on a surface of the first substrate to form a
first circuit, a second circuit and a conductive contact; providing
a second substrate having a first surface and a second surface;
mounting the second substrate to the surface of the first substrate
in which the first surface of the second substrate faces to the
first substrate to define a first chamber, a second chamber and at
least one micro channel, wherein the first circuit is configured in
the first chamber, the second circuit is configured in the second
chamber, and the micro channel extends outward from the first
chamber along the border surface of the first substrate and the
second substrate; forming a MEMS element and a reference element on
the second substrate, wherein the MEMS element corresponds to the
first circuit, and the reference element corresponds to the second
circuit; forming at least a first via and a second via, wherein the
first via and the second via penetrate the first surface and the
second surface of the second substrate, the first via is connected
to the micro channel, and the second via corresponds to the
conductive contact; introducing an anti-sticking material through
the first via and the micro channel to form an anti-sticking layer
on the inner surface of the first chamber; and filling a conductive
material to the first via and the second via to seal the first via
and electrically connect the second substrate and the conductive
contact.
2. The manufacture method of the pressure sensor according to claim
1, further comprising: forming at least one trench on the surface
of the first substrate or the first surface of the second substrate
to define the micro channel.
3. The manufacture method of the pressure sensor according to claim
1, wherein the micro channel comprises a bent portion bending to
horizontal or vertical direction.
4. The manufacture method of the pressure sensor according to claim
1, wherein the micro channel comprises a dam for reducing the inner
diameter of the micro channel.
5. The manufacture method of the pressure sensor according to claim
1, further comprising: forming a notch on a side of the first
surface or a side of the second surface of the second substrate for
thinning the MEMS element.
6. The manufacture method of the pressure sensor according to claim
1, further comprising: forming an anti-moving bump on the surface
of the first substrate corresponding to the MEMS element.
7. The manufacture method of the pressure sensor according to claim
1, wherein the second via is further connected to the micro
channel.
8. The manufacture method of the pressure sensor according to claim
1, wherein the conductive material in the second via and the second
substrate form an ohmic contact, wherein the ohmic contact region
comprises at least one of silicon, aluminum-copper alloy, titanium
nitride and tungsten.
9. The manufacture method of the pressure sensor according to claim
1, wherein the first substrate comprises a complementary metal
oxide semiconductor substrate.
10. The manufacture method of the pressure sensor according to
claim 1, further comprising: providing a third substrate, having a
notch region and a plurality of bracket structure; and connecting
the third substrate to the surface of the first substrate through
the bracket structure to place the second substrate in the notch
region.
11. The manufacture method of the pressure sensor according to
claim 10, wherein the third substrate comprises a channel
configured on the terminal of the bracket structure.
12. A pressure sensor, comprising: a first substrate, comprising a
metal layer, wherein the metal layer is partially exposed on a
surface of the first substrate to form a first circuit, a second
circuit and a conductive contact; a second substrate, comprising a
first surface, a second surface and at least one contact via, the
contact via penetrates the first surface and the second surface of
the second substrate and is sealed by a filler, wherein the second
substrate faces the surface of the first substrate with the first
surface and is electrically connected to the conductive contact,
wherein the second substrate comprising: a MEMS element,
corresponding to the first circuit and defining an airtight chamber
with the first substrate and the second substrate, wherein the
chamber comprises at least one micro channel extending to the
contact via; and a reference element, corresponding to the second
circuit and retaining a fixed distance with the second circuit; and
an anti-sticking layer, locating on the inner surface of the
chamber.
13. The pressure sensor according to claim 12, wherein the micro
channel comprises a bent portion bending to horizontal or vertical
direction.
14. The pressure sensor according to claim 12, wherein the micro
channel comprises a dam for reducing the inner diameter of the
micro channel.
15. The pressure sensor according to claim 12, wherein the micro
channel is configured on the first substrate.
16. The pressure sensor according to claim 12, wherein the micro
channel is configured on the second substrate.
17. The pressure sensor according to claim 12, wherein the MEMS
element comprises a notch configured on side of the first surface
or side of the second surface.
18. The pressure sensor according to claim 12, wherein an
anti-moving bump is configured on the surface of the first
substrate corresponding to the MEMS element.
19. The pressure sensor according to claim 12, wherein the second
substrate comprises a conductive via penetrating the first surface
and the second surface of the second substrate, wherein the
conductive via is electrically connected to the conductive contact
and the second substrate through an ohmic contact, and the ohmic
contact region comprises at least one of silicon, aluminum-copper
alloy, titanium nitride and tungsten.
20. The pressure sensor according to claim 19, wherein the
conductive via is integrated to the contact via.
21. The pressure sensor according to claim 12, wherein the first
substrate comprises a complementary metal oxide semiconductor
substrate.
22. The pressure sensor according to claim 12, further comprising:
a third substrate having a notch region and a plurality of bracket
structure, wherein the third substrate is configured above the
second substrate and is connected to the first substrate through
the bracket structure so that the second substrate is accommodated
in the notch region.
23. The pressure sensor according to claim 22, wherein the third
substrate comprises a channel configured on the terminal of the
bracket structure.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a pressure sensor and a
manufacture method thereof, particularly to a pressure sensor and
manufacture method thereof complied with the Microelectromechanical
System (MEMS) device.
[0003] 2. Description of the Prior Art
[0004] Since the development in 1970, the Microelectromechanical
System (MEMS) device has been improved from subject in the
laboratory research to that for high-level system integration. The
MEMS device also has a popular application and an amazing and
stable growth in the public consumable field. The MEMS device is
capable of achieving the functions of the device through detecting
or controlling the kinematic physical quantity of the movable MEMS
elements. Therefore, how to avoid failure of the MEMS device caused
by sticking of the movable MEMS element has been always one of the
most important goals of the MEMS device, particularly to the
pressure sensor with the airtight chamber.
SUMMARY OF THE INVENTION
[0005] The present invention is directed to providing a pressure
sensor and a manufacture method thereof implemented with the MEMS
device. In the semiconductor process, an anti-sticking layer is
coated on the inner surface of the airtight chamber to avoid
failure of the MEMS device caused by sticking of the movable MEMS
element.
[0006] The manufacture method of the pressure sensor according to
one embodiment of the present invention comprises: providing a
first substrate comprising a metal layer, wherein the metal layer
is partially exposed on a surface of the first substrate to form a
first circuit, a second circuit and a conductive contact; providing
a second substrate having a first surface and a second surface;
mounting the second substrate to the surface of the first substrate
in which the first surface of the second substrate faces to the
first substrate to define a first chamber, a second chamber and at
least one micro channel, wherein the first circuit is configured in
the first chamber, the second circuit is configured in the second
chamber, and the micro channel extends outward from the first
chamber along the border surface of the first substrate and the
second substrate; forming a MEMS element and a reference element on
the second substrate, wherein the MEMS element corresponds to the
first circuit, and the reference element corresponds to the second
circuit; forming at least a first via and a second via, wherein the
first via and the second via penetrate the first surface and the
second surface of the second substrate, the first via is connected
to the micro channel, and the second via corresponds to the
conductive contact; introducing an anti-sticking material through
the first via and the micro channel to form an anti-sticking layer
on the inner surface of the first chamber; and filling a conductive
material to the first via and the second via to seal the first via
and electrically connect the second substrate and the conductive
contact.
[0007] The pressure sensor according to another embodiment of the
present invention comprises a first substrate, a second substrate
and an anti-sticking layer. The first substrate comprises a metal
layer, wherein the metal layer is partially exposed on a surface of
the first substrate to form a first circuit, a second circuit and a
conductive contact. The second substrate comprises a first surface,
a second surface and at least one contact via, the contact via
penetrates the first surface and the second surface of the second
substrate and is sealed by filler, wherein the second substrate
faces the surface of the first substrate with the first surface and
is electrically connected to the conductive contact. The second
substrate comprises a MEMS element and a reference element. The
MEMS element corresponds to the first circuit and defining an
airtight chamber with the first substrate and the second substrate,
wherein the chamber comprises at least one micro channel extending
to the contact via. The reference element corresponds to the second
circuit and retaining a fixed distance with the second circuit. The
anti-sticking layer is configured on the inner surface of the
chamber.
[0008] Other advantages of the present invention will become
apparent from the following descriptions taken in conjunction with
the accompanying drawings wherein certain embodiments of the
present invention are set forth by way of illustration and
examples.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The foregoing aspects and many of the accompanying
advantages of this invention will become more readily appreciated
as the same becomes better understood by reference to the following
detailed descriptions, when taken in conjunction with the
accompanying drawings, wherein:
[0010] FIG. 1 is a cross-sectional diagram showing a pressure
sensor of a preferred embodiment of the present invention;
[0011] FIG. 2 is a schematic diagram showing the layout of the
chamber, the micro channel and the contact via of the pressure
sensor of a preferred embodiment of the present invention;
[0012] FIG. 3 is a cross-sectional diagram showing a pressure
sensor of another preferred embodiment of the present
invention;
[0013] FIG. 4 is a cross-sectional diagram showing a pressure
sensor of further preferred embodiment of the present
invention;
[0014] FIG. 5 is a partial schematic diagram showing the structure
of the micro channel of the pressure sensor of a preferred
embodiment of the present invention;
[0015] FIG. 6 is a partial schematic diagram showing the structure
of the micro channel of the pressure sensor of a preferred
embodiment of the present invention;
[0016] FIG. 7 is a partial cross-sectional diagram showing the
structure of the micro channel of the pressure sensor of a
preferred embodiment of the present invention;
[0017] FIGS. 8a to 8h are cross-sectional diagrams showing the
manufacture steps of the pressure sensor of a preferred embodiment
of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0018] The pressure sensor of the present invention is accomplished
with the MEMS device. Referring to FIG. 1 and FIG. 2, the pressure
sensor 1 of one preferred embodiment of the present invention
comprises a first substrate 11, a second substrate 12 and an
anti-sticking layer (not shown). The first substrate 11 comprises
at least one metal layer. In the embodiment shown in FIG. 1, the
first substrate 11 comprises the metal layer 111a and 111b, and the
metal layer 111b on the upper layer is partially exposed on the
surface of the first substrate 11. The exposed metal layer 111b is
capable of being a first circuit 113a, a second circuit 113b and a
conductive contact 113c. In one preferred embodiment, the first
substrate 11 is a complementary metal oxide semiconductor
substrate.
[0019] The second substrate 12 comprises a first surface 121 and a
second surface 122, and the second substrate 12 faces the surface
of the first substrate 11 with the first surface 121 and is
electrically connected to the conductive contact 113c of the first
substrate 11. For example, the second substrate 12 comprises at
least one conductive via 123b penetrating the first surface 121 and
the second surface 122 of the second substrate 12. The conductive
via 123b is electrically connected to the conductive contact 113c
and the second substrate 12 through an ohmic contact, wherein the
ohmic contact id formed by the conductive via 123b and the second
surface 122 of the second substrate 12 or the side wall of the
conductive via 123b. In one preferred embodiment, the ohmic contact
region is made of at least one of silicon, aluminum-copper alloy,
titanium nitride and tungsten. The second substrate 12 further
comprises a contact via 123a, and the contact via 123 also
penetrates the first surface 121 and the second surface 122 of the
second substrate 12 and is sealed by filler. In one preferred
embodiment, the filler in the contact via 123a may be the same or
different material with the conductive material (such as tungsten)
in the conductive via 123b. Here, it should be noted that the
conductive via 123b and the contact via 123a may be integrated
together. For example, the filler in the contact via 123a is a
conductive material, and the metal layer 111b connecting the
contact via 123a is a well-designed conductive contact as well, so
that the contact via 123a may be used as a conductive via and
provide an alternative conductive path of the electrical connection
between the first substrate 11 and the second substrate 12.
Besides, the conductive via 123b may be omitted as well.
[0020] Further, the second substrate 12 comprises a MEMS element
124 and a reference element 125. The MEMS element 124 corresponds
to the first circuit 113a of the first substrate 11 and defines an
airtight chamber 126 with the first substrate 11 and the second
substrate 12. The pressure difference between the inside and the
outside of the chamber 126 may create a deformation of the MEMS
element 124 forward or backward the first substrate 11. The MEMS
element 124 is electrically coupled to the first circuit 113a to
measure the deformation quantity of the MEMS element 124. The
reference element 125 corresponds to the second circuit 113b and
retains a fixed distance with the second circuit 113b. Simply
speaking, the reference element does not deform with the pressure
difference, so that the reference element 125 is electrically
coupled to the second circuit 113b to provide a stable reference
signal. In One preferred embodiment, the thickness of the reference
element 125 may be increased to avoid the reference element 125
deforming with the outside pressure difference.
[0021] Referring to FIG. 1, the first substrate 11 and the second
substrate further define a micro channel 115 extending from the
chamber 126 to the contact via 123a. In other words, the micro
channel 115 connects the chamber 126 and the contact via 123a.
Therefore, in the manufacture process, the anti-sticking material
may be introduced to the chamber 126 via the contact via 123a and
the micro channel 115, and form the anti-sticking layer on the
inner surface of the chamber 126. In one preferred embodiment, the
anti-sticking material may be the self-assembled monolayer (SAM)
material, such as dichlordimethylsilane (DDMS),
octadecyltrichlorsilane (OTS), perfluoroctyltrichlorsilane
(PFOTCS), perfluorodecyl-trichlorosilane (FDTS), or
fluoroalkylsilane (FOTS). The anti-sticking layer on the inner
surface of the chamber 126 is capable of avoiding the sticking of
MEMS element 124 to the first substrate 11. Furthermore, an
anti-moving bump 116 may be configured on the surface of the first
substrate 11 corresponding to the MEMS element 124 to reduce the
contacting area of the MEMS element 124 and the first substrate 11
and prevent sticking and failing of the MEMS element 124 and the
first substrate 11.
[0022] The third substrate 13 comprises a plurality of bracket
structure 131 surrounding a notch region 132. The third substrate
13 is configured above the second substrate 12 and is connected to
the first substrate 11 through the bracket structure 131 to place
the second substrate 12 in the notch region 132 of the third
substrate 13. In one preferred embodiment, the third substrate 13
is conductive and the contact pad 133 is provided at the terminal
of the bracket structure 131. The third substrate 13 is
eutectically bonded with the first substrate 11 so that the contact
region 113d of the contact pad 133 and the first substrate 11 form
a low resistance conductive contact. For example, the third
substrate 13 may be made of at least one of silicon-doped ceramics
having conductive plating, glass having Indium Tin Oxide (ITO)
coating, and Tantalum oxide. The third substrate 13 is also
provided with a channel 134 connecting the notch region 132 and the
outside to make the pressure of the notch region 132 and the
outside equal. In one preferred embodiment, the channel 134 is
configured on the terminal of the bracket structure 131.
[0023] In the embodiment shown in FIG. 1, the micro channel 115 is
configured on side of the first substrate 11, which forms a trench
on the surface of the first substrate 11 and then connects the
first substrate 11 and the second substrate 12 to form the micro
channel 115. In one preferred embodiment, referring to FIG. 3, the
micro channel 115 may be also configured on one side of the second
substrate 12, which forms a trench on the first surface 121 of the
second substrate 12 and then connects the first substrate 11 and
the second substrate 12 to form the micro channel 115.
[0024] In the embodiment shown in FIG. 1, a notch is formed on side
of the first surface 121 of the second substrate 12 for thinning
the MEMS element 124. The notch 124a may be also formed on one side
of the second surface 122 of the second substrate 12 for thinning
the MEMS element 124, as shown in FIG. 4. In one preferred
embodiment, a notch 125a may be also formed on side of the second
surface 122 of the second substrate 12 for thinning the reference
element 125. In order to avoid the deformation between the thinned
reference element 125 and the outside pressure difference, a
channel 125b may be configured to connect the chamber 127 which is
defined by the reference element 125 and then there is no pressure
difference between the chamber 127 and the outside environment.
Hence, the reference element 125 will not have the deformation
caused by the outside pressure difference.
[0025] Referring FIG. 5 which is a partial schematic diagram
showing the structure of the micro channel of the unconnected
second substrate 12. In the embodiment shown in FIG. 5, the micro
channel 115 comprises a bent portion 115a bending to horizontal
direction (along the border surface of the first substrate and the
second substrate). Therefore, when the filler is filled in the
contact via 123a, the filler will be deposited in the bent portion
115a without contaminating the chamber 126. It may be understood
that the same function may be also performed by the micro channel
115 having a bent portion bending to vertical direction (vertical
to the first surface of the second substrate).
[0026] Referring to FIG. 6, in one preferred embodiment, at least
one dam 115b may be configured in the micro channel 115. The dam
115b may reduce the inner diameter of the micro channel 115, and
then the anti-sticking material may pass through and the filler
will tend to be deposited in the dam 115b without contaminating the
chamber 126. In another preferred embodiment, referring to FIG. 7,
the dam 115b may also reduce the inner diameter of the micro
channel 115 on vertical direction and only the above portion of the
micro channel 115 can be passed through, so that the filler may be
blocked by the dam 115b before or between the dam 115b.
[0027] Please refer to FIGS. 8a to 8h which are cross-sectional
diagrams showing the manufacture steps of the pressure sensor of a
preferred embodiment of the present invention. First, a first
substrate 11 comprising a driving circuit and/or a detecting
circuit is provided. The analog and/or digital circuits may be used
in the first substrate 11, and are generally implemented by using
application-specific integrated circuit (ASIC) designed devices.
The first substrate 11 may be also named the electrode substrate.
In one preferred embodiment of the present invention, the first
substrate 11 may be any substrate with suitable mechanic stiffness,
such as complementary metal oxide semiconductor (CMOS) substrate or
glass substrate. Only one chip is shown in the cross-sectional
figures, however, it is understood, a plurality of chips may be
formed on one substrate. It is only used for explaining the present
invention with single device, not for limiting the manufacture
method. In the following specification, a complete explanation of
the wafer level process applied to a substrate to manufacture a
plurality of chips or devices will be described. After
manufacturing the devices, the dicing and singulation technologies
will be applied to produce the single-device package to fit all
applications.
[0028] Referring to FIG. 8a, a first dielectric layer 112a with a
predetermined thickness is configured on the first substrate 11. In
one preferred embodiment, the first dielectric layer 112a may be a
SiO.sub.2 layer; however, other suitable materials may be used in
the present invention as well and are also in the scope of the
present invention. For example, in another embodiment,
Si.sub.3N.sub.4 or Silicon oxynitride (SiON) may be deposited to
form the first dielectric layer 112a. In a further embodiment, a
polysilicon material, including the amorphous polysilicon, may be
deposited to form the first dielectric layer 112a. Any material
with appropriate characteristic, including having mighty connection
to the substrate, having great attachment to the first substrate
11, and having suitable mechanic stiffness, may be used to replace
the Si.sub.xO.sub.y material. In some specific applications, a
buffer layer may be used in the deposition process of the first
dielectric layer 112a.
[0029] In some embodiments, the first dielectric layer 112a is
formed by multiple deposition and polishing processes. For example,
the first portion of the first dielectric layer 112a may be formed
by using the high-density plasma (HDP) deposition process, and then
using the chemical mechanical planarization (CMP) process to
polish. The density of the device feature is variable resulted in a
relative horizontal position difference, in other words, the
deposition layer probably has an uneven upper surface. Hence, the
multiple deposition and polishing processes may form an even and
flat surface. The example of the deposition technology includes
Tetraethyl Orthosilicate (TEOS), High-Density Plasma (HDP),
Chemical Vapor Deposition (CVD), Low Pressure Chemical Vapor
Deposition (LPCVD) and Thermal Oxidation. Besides, other materials
may be also applied when a final layer (such as oxide) is
covered.
[0030] In some embodiments, the deposition of the first dielectric
layer 112a is processed based on the structure of the substrate.
For example, when the first substrate 11 is a complementary metal
oxide semiconductor (CMOS) substrate, the higher temperature
deposition process may damage the metal layer or cause the
diffusion effect on the contacting surface of the circuits, and
some circuits on the substrate may be affected. Therefore, in one
specific embodiment of the present invention, the lower temperature
deposition, patterning and etching processes, such as processes in
temperature lower than 500.degree. C., are used to form the layers
shown in FIGS. 8a to 8h. In another specific embodiment of the
present invention, the deposition, patterning and etching processes
are performed in the temperature lower than 450.degree. C. to form
the layers shown in figures. After the first dielectric layer 112a
is formed, it may be further patterned and etched to form multiple
first interconnect via 118a. The first interconnect via 118a
provides the electrical connection between the first substrate 11
and the first metal layer 111a later formed on the first dielectric
layer 112a, and this process will be further explained later.
[0031] Then, a first metal layer 111a is formed above the first
dielectric layer 112a. The first metal layer fills in the first
interconnect via 118a. In some embodiments, the first interconnect
via 118a may be filled by a conductive material (such as tungsten).
In one preferred embodiment, the first metal layer 111a is
deposited by using plating, Physical Vapor Deposition (PVD) or
Chemical Vapor Deposition (CVD) processes. FIG. 8a shows the first
substrate 11 and the patterned first metal layer 111a after the
etching process. For thoroughly explaining the present invention, a
lithography process is not shown in the manufacture process,
wherein a photoresist layer is deposited on the first metal layer
111a and then is patterned to form an etching mask. In the
lithography process, the size of the etching mask may be strictly
controlled, and may be performed by using any suitable material
resisting the etching process while etching the metal layer. In one
specific embodiment, the Si.sub.3N.sub.4 is used as the etching
mask. Although a one-dimensional cross-sectional diagram is shown
in FIG. 8a, it should be understood that a predetermined
two-dimensional pattern is formed on the metal layer, however. In
one embodiment, the first metal layer 111a is made of aluminum,
copper, aluminum-copper-silicon alloy, tungsten and titanium
nitride.
[0032] Then, a second dielectric layer 112b is formed above the
first dielectric layer 112a. In some preferred embodiments, the
process and material to form the second dielectric layer 112b is
similar to the process of forming the first dielectric layer 112a.
In other embodiments, the process and material to form the second
dielectric layer 112b is different to the process of forming the
first dielectric layer 112a. In other embodiments, the process and
material to form the second dielectric layer 112b is partially
similar to and partially different from the process of forming the
first dielectric layer 112a. After the second dielectric layer 112b
is formed, it will then be patterned and etched to form multiple
second interconnect via 118b. The second interconnect via 118b
provides the electrical connection between the first metal layer
111a and the second metal layer 111b later formed on the second
dielectric layer 112b, and this process will be explained more
later.
[0033] Then, a second metal layer 111b is formed above the second
dielectric layer 112b. The second metal layer 111b fills in the
second interconnect via 118b. In some embodiments, the second
interconnect via 118b may be filled by a conductive material (such
as tungsten). The patterned second metal layer 111b may be used as
the electrode of the MEMS device, such as the first circuit 113a
and the second circuit 113b used as detecting and/or driving
circuits, the conductive contact 113c electrically connected to the
second substrate 12, or the contact region 113d connecting to the
third substrate 13. The contact region 113d comprises a conductive
material having sufficient mechanic stiffness to support the
connection interface. In one specific embodiment, the contact
region 113d and the first substrate 11 form a low resistance ohmic
contact. In some embodiments, the contact region 113d is made of
germanium, aluminum or copper. In other embodiments, the contact
region 113d may be also made of other materials, such as gold,
indium, or other solder capable of bottom-mounting and moistly
improving metal stack.
[0034] Referring to FIG. 8b, a third dielectric layer 112c is
formed above the second dielectric layer 112b. The process and
material to form the third dielectric layer 112c is similar to the
process of forming the second dielectric layer 112b shown in FIG.
8a. Then, the third dielectric layer 112c is patterned to form at
least one trench 115c. After connecting the second substrate 12 and
the first substrate 11, the trench 115c may form the micro channel
115. The etching process comprise one or more than one etching
steps, such as anisotropic etching, oxide etching, wet etching or
dry etching, for example Reactive Ion Etching (RIE). In one
preferred embodiment, the etching process may define one or
multiple mechanic anti-moving structures of the MEMS elements,
which are anti-moving bumps 116. In one preferred embodiment, one
or multiple buffer layers may be used as etching stop layer. For
example, the metal layer 114 of the first metal layer 111a may
prevent the exposure of the first dielectric layer 112a. The person
skilled in the art should understand the change, modify or replace
of the embodiments is still in the scope of the present invention.
In one preferred embodiment, the etching process may also define
multiple fences 117. The fences 117 are configured for surrounding
the contact region 113d of the third substrate 13 to prevent
migrating of metal in the connection process and failing of the
device.
[0035] Referring to FIG. 8c, a second substrate 12 is provided and
a notch 124a is formed on the first surface 121 of the second
substrate 12. When the second substrate 12 and the first substrate
11 are connected, the notch 124a may help to reduce the
interference from the first substrate 11. It is understood that the
notch may be also formed on the position corresponding to the
reference element 125, and the final thickness of the reference
element 125 has to thicker than that of the MEMS element 124, or a
suitable channel has to be formed to avoid the deformation of the
reference element 125. It has to be noted that this step may be
also omitted when manufacturing the embodiment shown in FIG. 4, and
the notch 124a will be formed on the second surface 122 of the
second substrate 12 in the later steps. Further, for manufacturing
the embodiment shown in FIG. 3, the trench corresponding to the
micro channel 115 has to be formed on the first surface 121 of the
second substrate 12 in this step.
[0036] Referring to FIG. 8d, the first surface 121 of the second
substrate 12 is faced to the first substrate 11 and is mounted to
the first substrate 11. The mounting of the second substrate 12 and
the first substrate 11 may be achieved by using one of the methods
of fusion bond, eutectic bonding, conductive eutectic bonding,
soldering and bonding. In some embodiments, the Anisotropic
Conductive Film (ACF) may be used to bond the second substrate 12
to the first substrate 11. After the second substrate 12 and the
first substrate 11 are connected, a first chamber 126, a second
chamber 127 and at least one micro channel 115 are defined, wherein
the first circuit 113a is configured in the first chamber 126, the
second circuit 113b is configured in the second chamber 127, and
the micro channel 115 extends outward from the first chamber 126
along the border surface of the first substrate 11 and the second
substrate 12.
[0037] Then, a grinding and/or other thinning procedures are
performed to the second substrate 12 to thin the second substrate
12 to a predefined thickness. As shown in FIG. 8e, in some
embodiments, the remained thickness of the thinned region
corresponding to the MEMS element 124 is about 10 .mu.m to 100
.mu.m, and the MEMS element 124 may be deformed with the pressure
difference. The predefined thickness may be achieved by using the
traditional thinning technology, such as chemical mechanical
planarization (CMP), wet etching and/or dry etching, for example
Reactive Ion Etching (RIE) technologies. There is no stopping layer
to end the thinning process in the embodiment shown in FIG. 8d, and
the thinning process adopts an exact control. Without the exact
control of the thinning process, the thickness of the second
substrate 12 may be thinner or thicker than the predefined
thickness, and the function of the manufactured MEMS device will be
affected. In other embodiments, an etching stopping layer is
integrated into the second substrate 12 for the exact control of
the thinning process. The person skilled in the art should
understand the change, modify or replace of the embodiments is
still in the scope of the present invention.
[0038] Referring to FIG. 8e, the second substrate 12 is patterned
and etched to form a first via 128a and a second via 128b. The
first via 128a and the second via 128b penetrate the first surface
121 and the second surface 122 of the second substrate 12. The
first via 128a is connected to the micro channel 115, and the first
chamber 126 may be connected to the outside through the first via
128a and the micro channel 115. The second via 128b corresponds to
the conductive contact 113c to expose the conductive contact
113c.
[0039] Referring to FIG. 8f, since the first chamber 126 may be
connected to the outside through the first via 128a and the micro
channel 115, the anti-sticking material may be introduced into the
chamber 126 through the first via 128a and the micro channel 115 to
form an anti-sticking layer (not shown) on the inner surface of the
first chamber 126. The anti-sticking material has been described
above and will not be repeated again here.
[0040] Referring to FIG. 8g, then, a filler is filled into the
first via 128a to seal the first via 128a. A conductive material
(such as tungsten) is introduced to the second via 128b to make the
second via 128b be a conductive via 123b and electrically connect
the second substrate 12 and the conductive contact 113c of the
first substrate 11. In one preferred embodiment, the filler in the
first via 128a may be the same as that in the second via 128b. As
described above, the forming and filling the first via 128a and the
second via 128b may be finished together in the same process.
Therefore, there is no extra processing step needed to open and
close the micro channel 115, and the process is essentially
simplified.
[0041] Referring to FIG. 8h, a third substrate 13 is provided. In
some embodiments, the third substrate 13 is made of doped silicon,
ceramic with a conductive coating, glass covered by a conductive
coating (such as ITO), or metal layer like Tantalum oxide. A
sticking layer is placed on the surface of the third substrate 13.
The sticking layer may assist the mounting between the third
substrate 13 and the first substrate 11. In some embodiments, the
sticking layer is formed by depositing a seed layer, such as
titanium/gold, and then depositing a conductive layer (such as
plating gold). Then, the third substrate 12 is patterned and etched
to form a plurality of bracket structure 131. The third substrate
13 is etched to form the bracket structure 131, and a notch region
132 is formed on the third substrate 13. The partial sticking layer
is remained on the bracket structure 131 to form the contact pad
133. The notch region 132 may be configured surrounding the second
substrate 12. The horizontal size of the notch region 132 is
selected according to the geometric structure of the second
substrate 112 covered by the third substrate 13. In one embodiment,
in the process of forming the bracket structure 131, one or
multiple trenches may be formed at the terminal of the bracket
structure 131. When the third substrate 13 is connected to the
first substrate 11 through the bracket structure 131, the trenches
may be used as the channel 134 connecting the notch region 132 and
the outside, as shown in FIG. 1. The connection step of the third
substrate 13 and the first substrate 11 may be achieved by using
one of the methods of fusion bond, glass frit bonding, eutectic
bonding, conductive eutectic bonding, soldering and bonding. In
some embodiments, the temperature while connecting the third
substrate 13 and the first substrate 11 is lower than the
temperature while connecting the second substrate 12 and the first
substrate 11 to protect the MEMS element 124. The third substrate
13 is conductive and may shield the electromagnetic disturbance
(EMI) of the second substrate 12. It is noted that the third
substrate 13 is an optional device, and that is under the condition
without the third substrate 13, the pressure sensor of the present
invention may be also functioned.
[0042] To sum up the foregoing descriptions, the pressure sensor
using the MEMS device and the manufacture method thereof require no
extra semiconductor process to achieve the present invention that
open the micro channel, coat the anti-sticking layer on the inner
surface of the chamber, and then seal the micro channel to keep the
chamber airtight. Therefore, the pressure sensor using the MEMS
device according to the present invention and the manufacture
method thereof may essentially simplify the manufacture process to
coat the anti-sticking layer on the inner surface of the airtight
chamber to prevent the failure of the MEMS device caused by
sticking of the movable MEMS element.
[0043] While the invention can be subject to various modifications
and alternative forms, a specific example thereof has been shown in
the drawings and is herein described in detail. It should be
understood, however, that the invention is not to be limited to the
particular form disclosed, but on the contrary, the invention is to
cover all modifications, equivalents, and alternatives falling
within the spirit and scope of the appended claims.
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