U.S. patent application number 11/260090 was filed with the patent office on 2006-06-29 for mems device package and method for manufacturing the same.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Duck-hwan Kim, Jong-seok Kim, Kuang-woo Nam, Yun-kwon Park, In-sang Song, Seok-chul Yun.
Application Number | 20060141652 11/260090 |
Document ID | / |
Family ID | 36612204 |
Filed Date | 2006-06-29 |
United States Patent
Application |
20060141652 |
Kind Code |
A1 |
Kim; Jong-seok ; et
al. |
June 29, 2006 |
MEMS device package and method for manufacturing the same
Abstract
A micro electromechanical system (MEMS) device package and a
method of manufacturing the same are provided. The MEMS device
package includes: a device substrate with a MEMS active device
being formed on the top surface thereof; internal electrode pads,
each of which is positioned on the opposite side of the MEMS active
device and electrically connected to the MEMS active device;
sealing pads positioned outside of the internal electrode pads; a
closure substrate joined to the device substrate through the
sealing pads, the closure substrate having via holes formed at the
areas where the internal electrode pads are positioned; and
external electrode pads formed on the top surface of the closure
substrate in such a way that the external electrode pads are
electrically connected to the internal electrode pads through the
via holes. The internal electrode pads and the sealing pads are
formed from an identical material such as Au and thus the device
substrate and the closure substrate are bonded to each other with
direct bonding such as Au--Au direct bonding via the sealing
pads.
Inventors: |
Kim; Jong-seok; (Hwasung-si,
KR) ; Park; Yun-kwon; (Dongducheon-si, KR) ;
Song; In-sang; (Seoul, KR) ; Kim; Duck-hwan;
(Goyang-si, KR) ; Nam; Kuang-woo; (Yongin-si,
KR) ; Yun; Seok-chul; (Yongin-si, KR) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
|
Family ID: |
36612204 |
Appl. No.: |
11/260090 |
Filed: |
October 28, 2005 |
Current U.S.
Class: |
438/48 |
Current CPC
Class: |
B81B 7/007 20130101 |
Class at
Publication: |
438/048 |
International
Class: |
H01L 21/00 20060101
H01L021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 27, 2004 |
KR |
2004-112700 |
Claims
1. A micro electromechanical system (MEMS) device package
comprising: a device substrate with a MEMS active device being
formed on a top surface thereof; internal electrode pads, each of
which is positioned on the opposite side of the MEMS active device
and electrically connected to the MEMS active device; sealing pads
positioned outside of the internal electrode pads; a closure
substrate joined to the device substrate through the sealing pads,
the closure substrate comprising via holes formed at the areas
where the internal electrode pads are positioned; and external
electrode pads formed on the top surface of the closure substrate
in such a way that the external electrode pads are connected to the
internal electrode pads through the via holes.
2. The MEMS device package of claim 1, wherein the internal
electrode pads and the sealing pads are formed from an identical
material and the device substrate and the closure substrate are
bonded to each other with direct bonding using a material which is
identical to the material forming the internal electrode pads and
the sealing pads.
3. The MEMS device package of claim 1, wherein the external
electrode pads are formed from a material identical to the material
which forms the internal electrode pads and the sealing pads of
claim 2.
4. The MEMS device package of claim 2, wherein the identical
material is Au.
5. A method of manufacturing a micro electromechanical system
(MEMS) device package, the method comprising: a) providing a device
substrate having a MEMS active device and one or more lead lines
electrically connected with the MEMS active device; b) forming, on
a closure substrate, internal electrode pads and sealing pads
positioned outside of the internal electrode pads to a
predetermined height; c) bonding the device substrate and the
closure substrate to each other through the sealing pads in such a
way that the MEMS active device is positioned in the space provided
by the internal electrode pads and the internal electrode pads come
into contact with the lead lines; d) polishing the closure
substrate to a predetermined thickness; e) forming via holes at the
positions where the internal electrode pads are positioned on the
closure substrate; and f) forming external electrode pads which are
electrically connected with the internal electrode pads through the
via holes.
6. The method of claim 5, wherein the forming of internal electrode
pads and sealing pads on a closure substrate comprises: b1) coating
a seed layer on the entire surface of the closure substrate; b2)
forming a plating frame for use in forming the internal electrode
pads and the sealing pads on the seed layer through a
photolithography process; b3) electrically plating a material,
which is identical to the material forming the seed layer on the
closure substrate, over the plating frame; and b4) removing the
plating frame.
7. The method of claim 6, wherein a material used for the seed
layer is Au.
8. The method of claim 7, wherein Au is coated to a thickness of
about 1,000 .ANG..
9. The method of claim 5, wherein the bonding of the device
substrate and the closure substrate to each other through the
sealing pads employs direct bonding which uses a material identical
to the material forming the internal electrode pads and the sealing
pads.
10. The method of claim 9, wherein the identical material is
Au.
11. The method of claim 10, wherein the direct bonding using Au is
performed at a temperature of 320.+-.10.degree. C. within about 20
minutes.
12. The method of claim 5, wherein the thickness of the closure
substrate in the step d) is about 40 .mu.m.
13. The method of claim 5, wherein, to form via holes, the closure
substrate is Inductively Coupled Plasma (ICP)-etched.
14. The method of claim 5, wherein the forming of external
electrode pads comprises sputtering a material which is identical
to the material forming the internal electrode pads and the sealing
pads.
15. The method of claim 14, the material sputtered to form external
electrode pads is Au.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from Korean Patent
Application No. 2004-112700 filed Dec. 27, 2004 in the Korean
Intellectual Property Office, the disclosure of which is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Apparatuses and methods consistent with the present
invention relate to a micro electromechanical system (MEMS) device
package and a method for manufacturing the same.
[0004] 2. Description of the Related Art
[0005] MEMS is the integration of sensors, micro actuators,
gyroscopes, precise machine parts, etc. using semiconductor
processing technology. As a high level of precision, product
uniformity, and superior productivity required for semiconductor
processing are applied to MEMS, MEMS is recognized as a technology
capable of improving performances of products while reducing
costs.
[0006] MEMS devices such as acceleration sensors, angular velocity
sensors, resonant gyroscopes, or the like are packaged for the
purpose of enhancing protectability and/or sensitivity thereof. As
high density and miniaturization of MEMS devices have been realized
due to the rapid development of technologies for manufacturing MEMS
devices, it is also required for packages to be correspondingly
miniaturized. For this purpose, Wafer Scale Package (WSP)
application for packaging devices in a wafer state is frequently
attempted.
[0007] FIG. 1 is a cross-sectional view schematically showing an
example of a conventional MEMS device package. As shown in the
drawing, a device substrate 1 is provided with a MEMS active device
2, and a glass closure substrate 3 is joined to the device
substrate 1 for protecting the MEMS active device 2. The MEMS
active device 2 typically has a spring structure and a stage
supported by the spring structure.
[0008] In addition, internal electrode pads 5 are formed on the
device substrate 1, wherein each of the internal electrode pads is
positioned on the opposite side of the MEMS active device 2 and
electrically connected to the MEMS active device 2. A cavity 4 is
formed under the glass closure substrate 3 for providing a space
for receiving the MEMS active device 2, wherein the glass closure
substrate 3 and the device substrate 1 are anodic-bonded to each
other.
[0009] In addition, via holes 6 are formed on the opposite sides of
the glass closure substrate 3, and external electrode pads 7, which
are connected to the internal electrode pads 5, are formed through
the via holes 6. Here, the via holes 6 are formed through a
sandblasting process, and the external electrodes 7 are formed by
filling a metallic material (typically Al) in the via holes 6
through a sputtering process. The external electrode pads 7 are
connected to a signal line on a circuit board not shown in the
figure through a wire, a bump or the like.
[0010] However, a conventional MEMS device package as described
above inevitably has a thick glass closure substrate 3 due to the
bonding structure between the glass closure substrate 3 and a
silicon-based device substrate 1 and the manufacturing process of
the MEMS device package, whereby there is a limit in reducing the
size of the package due to the via holes 6 in the glass substrate
3. In other words, due to a large size and a high height, such a
conventional MEMS package occupies a large volume in an apparatus
incorporating it, thereby causing the miniaturization of the
apparatus to be hindered.
[0011] Furthermore, because such a conventional MEMS package
employs a closure substrate 3 formed from glass, the processes for
forming the via holes 6 and the external electrode pads 7 are
difficult to perform and require much time, thereby causing a
decrease in yield and productivity.
[0012] Such a conventional MEMS package also has a problem in that
the MEMS active device 2 may be deformed or damaged due to high
temperature (typically about 460.degree. C.) at the time of
anodic-bonding and has basic stress due to the difference in
thermal expansion coefficient between the glass closure substrate 3
and the silicon-based device substrate 1.
[0013] Moreover, a problem of reliability may be presented because
the connection of a circuit by means of the internal electrode pads
5 formed from a silicon material and the external electrode pads 7
formed from a metallic material produces a very high inductance in
relation to RF signals of high frequency and electrical contact
resistance at the contact parts, thereby causing a high loss in
signal.
SUMMARY OF THE INVENTION
[0014] Accordingly, an illustrative, non-limiting embodiment of the
present invention has been made to solve the above-mentioned
problems, and an aspect of the present invention is to provide a
MEMS device package, in which a closure substrate formed from a
material identical to that of a device substrate is employed so as
to reduce the stress caused by a difference in thermal expansion
coefficient, and in which via holes for wiring of electrodes can be
simply fabricated and a simple metal deposition process can be
employed, so that the MEMS device package can be minimized in size,
and a method of manufacturing such a MEMS device package.
[0015] Another aspect of the present invention is to provide a MEMS
device package, in which a device substrate and a closure substrate
are bonded to each other with direct bonding, such as Au--Au direct
bonding, which uses a material identical to the material forming
the internal electrode pads and the sealing pads of the MEMS device
package, so that the package is stable and capable of enhancing a
yield, and a method of manufacturing such a MEMS device
package.
[0016] A still further aspect of the present invention is to
provide a MEMS device package, in which a circuit connection
structure is formed by contacting members formed from a same or
highly conductive material so as to minimize the loss in signal,
and a method of making such a MEMS device package.
[0017] In order to achieve the above-mentioned aspects, there is
provided a MEMS device package which includes: a device substrate
with a MEMS active device being formed on the top surface thereof;
internal electrode pads, each of which is positioned on the
opposite side of the MEMS active device and electrically connected
to the MEMS active device; sealing pads positioned outside of the
internal electrode pads; a closure substrate joined to the device
substrate through the sealing pads, the closure substrate having
via holes formed at the areas where the internal electrode pads are
positioned; and external electrode pads formed on the top surface
of the closure substrate in such a way that the external electrode
pads are electrically connected to the internal electrode pads
through the via holes.
[0018] The internal electrode pads and the sealing pads may be
formed from an identical material such as Au, and the device
substrate and the closure substrate may be bonded to each other
with direct bonding such as Au--Au direct bonding. In addition, the
external electrodes may also be formed from a material identical to
the material forming the internal electrode pads and the sealing
pads.
[0019] According to another aspect of the present invention, there
is provided a method of manufacturing a MEMS device package. The
method may include following steps: a) providing a device substrate
having a MEMS active device and one or more lead lines electrically
connected with the active device; b) forming, on a closure
substrate, internal electrode pads and sealing pads positioned
outside of the internal electrode pads to a predetermined height;
c) bonding the device substrate and the closure substrate to each
other through the sealing pads in such a way that the MEMS active
device is positioned in a space provided by the internal electrode
pads and the internal electrode pads come into contact with the
lead lines; d) polishing the closure substrate to a predetermined
thickness; e) forming via holes at the positions where the internal
electrode pads are positioned on the closure substrate; and f)
forming external electrode pads which are electrically connected
with the internal electrode pads through the via holes.
[0020] The step b) of the above method may include sub-steps of:
b1) coating a seed layer on the entire surface of the closure
substrate; b2) forming a plating frame for use in forming the
internal electrode pads and the sealing pads on the seed layer
through a photolithography process; b3) electrically plating a
material such as Au which is identical to the material forming the
seed layer on the closure substrate, over the plating frame; and
b4) removing the plating frame.
[0021] In the above step b1), Au, as a material to form the seed
layer, may be coated to a thickness of about 1,000 .ANG..
[0022] In addition, in the step c) of the above method, the bonding
of the device substrate and the closure substrate to each other
through the sealing pads may employ direct bonding using a material
which is identical to the material forming the internal electrode
pads and the sealing pads. For such direct bonding, Au--Au direct
bonding may be performed at a temperature of 320.+-.10.degree. C.
within about 20 minutes.
[0023] The thickness of the closure substrate used in the step d)
of the above method may be about 40 .mu.m.
[0024] In the step e) of the above method, in order to form the via
holes, the closure substrate may be etched using Inductively
Coupled Plasma (ICP).
[0025] In the step f) of the above method, to form external
electrode pads on the closure substrate, a material, such as Au,
identical to the material which forms the internal electrode pads
and the sealing pads may be sputtered.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The above aspects and features of the present invention will
be more apparent from the description for exemplary embodiments of
the present invention taken with reference to the accompanying
drawings, in which:
[0027] FIG. 1 is a schematic structural view of a conventional MEMS
device package;
[0028] FIG. 2 is a schematic structural view of a MEMS device
package according to an exemplary embodiment of the present
invention; and
[0029] FIGS. 3A to 3G show a process of manufacturing the MEMS
device according to an exemplary embodiment of the present
invention.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0030] Hereinbelow, an exemplary embodiment of the present
invention is described in detail with reference to accompanying
drawings.
[0031] FIG. 2 is a schematic structural view of a MEMS device
package according to an exemplary embodiment of the present
invention. As shown in the drawing, a MEMS active device 11 is
formed on the central part of the top surface of a device substrate
10. The MEMS active device 11 typically comprises a spring element,
a stage supported by the spring element and electrodes for
detecting the displacement of the stage or supplying a driving
force for the stage. Such a MEMS active device 11 does not limit
the technical scope of the present invention. In addition, lead
lines 13 electrically connected to the MEMS active device 11 are
formed on the device substrate 10.
[0032] Internal electrode pads 20 having a predetermined height are
placed on the device substrate 10, wherein each of the internal
electrode pads 20 is positioned on the opposite side of the MEMS
active device 11 in order to provide a space for positioning the
MEMS active device and connected with the lead lines 13 to form an
electric path for the MEMS active device. The internal electrode
pads 20 are formed from Au.
[0033] At the outside of the internal electrode pads 20, there are
provided sealing pads 30 formed from Au like the internal electrode
pads 20 to a height equal to that of the internal electrode pads
20.
[0034] A closure substrate 40 is joined to the device substrate 10
via the sealing pads 30. The top and bottom surfaces of the
internal electrode pads 20 and the sealing pads 30, i.e., the
interfaces thereof with the device substrate 10 and the closure
substrate 40, are formed with Au layers 21a, 21b, 31a and 31b
having a thickness of about 1,000 .ANG., respectively.
[0035] Therefore, because the device substrate 10 and the closure
substrate 40 are bonded to each other with Au--Au direct bonding,
it is possible to bond them within a shorter length of time and at
a lower temperature as compared to the anodic bonding of a glass
substrate and a silicon substrate in the prior art. The
above-mentioned temperature is about 320.degree. C. and the
above-mentioned bonding time is about 20 minutes. This means that
it is possible to greatly reduce the deformation and damage of a
device as compared to the prior art. In addition, the present
invention can avoid the stress problem caused by the difference in
thermal expansion coefficient in the prior art because the device
substrate 10 and the closure substrate 40 are formed from an
identical material.
[0036] Furthermore, via holes 41 are formed at the areas where the
internal electrode pads 20 of the closure substrate 40 are formed
to expose the internal electrode pads 20, wherein external
electrode pads 50 are formed in the via holes 41 to be electrically
connected to the internal electrode pads 20.
[0037] The via holes 41 are formed through Inductively Coupled
Plasma (ICP) etching and the external electrode pads 50 are formed
through sputtering, wherein, because the via holes 41 are formed in
the thin substrate 40 rather than in a glass substrate, the via
holes 41 can be formed through a simple etching process rather than
a sandblasting process, and the sputtering process is also
simple.
[0038] In addition, the external electrode pads 50 are formed from
Au, which enables electric connection with the same and high
conductive material. Such a circuit connection construction enables
to lower a loss in signal because it has a lower contact resistance
and a lower inductance with respect to RF signals of high frequency
as compared to the conventional connection of silicon to
aluminum.
[0039] In this manner, the inventive MEMS device package can be
thinned and miniaturized by employing a thin closure substrate 40
and can reduce a loss in signal because it has an electric signal
path, of which the internal resistance is retained at a lower
level. Furthermore, because the external electrode pads 50 are
formed on the surface of the closure substrate 40, the inventive
MEMS device package can be mounted on a circuit board in a direct
bonding fashion and plural packages can be easily stacked.
[0040] Now, a method of manufacturing the inventive MEMS device
package is described in detail with reference to FIGS. 3A to 3G.
Because conventional processes such as laminating, patterning, etc.
are employed in the inventive method, the processing processes are
not specifically described.
[0041] At first, as shown in FIG. 3A, Au is coated on the entire
surface of a closure substrate with a thickness of about 1,000
.ANG. to form a seed metal layer 110, and a plating frame 120 is
formed on the seed metal layer through a photolithographic process
or the like. The plating frame 120 is used for forming internal
electrode pads 20 and sealing pads 30.
[0042] Then, as shown in FIG. 3B, Au is electrically plated through
the plating frame 120, then the plating frame 120 is removed, and
then the exposed seed metal layer is removed.
[0043] Through this process, as shown in FIG. 3C, a structure with
the internal electrode pads 20 and the sealing pads 30 formed on
the inner side of the closure substrate 40 is prepared.
[0044] Thereafter, as shown in FIG. 3D, a device substrate 10
having a previously prepared active device 11 and lead lines 13 is
bonded to the closure substrate 40 using the sealing pads 30. At
this time, the MEMS active device 11 is positioned within a space
formed by the internal electrodes 20 and connected to the lead
lines 13.
[0045] Because the above-mentioned bonding is Au--Au direct bonding
between the sealing pads 30 formed from Au and an Au layer 31b
formed on the device substrate 10, it is possible to lower the
bonding temperature and reduce the length of bonding time as
compared to the conventional anodic bonding. The bonding
temperature is about 320.degree. C. and the length of bonding time
may be around 20 minutes. Therefore, the possibility of deforming
or damaging the device at the time of bonding can be reduced as
compared to the prior art.
[0046] In addition, because the substrates of a same material and
hence a same thermal expansion coefficient are bonded to each other
unlike the conventional glass substrate to silicon substrate
bonding, it is possible to avoid the occurrence of stress caused
due to the difference in thermal expansion coefficient, thereby
providing a more reliable MEMS device package.
[0047] After the device substrate 10 and the closure substrate 40
have been bonded to each other as described above, as shown in FIG.
3E, the closure substrate 40 is polished to a predetermined
thickness, which is about 40 .mu.m. The polishing is performed
according to a conventional process which is implemented by
grinding, lapping and chemical mechanical polishing in this
sequence.
[0048] Then, as shown in FIG. 3F, via holes 41 for wiring of the
electrodes are formed on predetermined positions, i.e., on the
areas where the internal electrode pads 20 are positioned on the
closure substrate polished to the predetermined thickness. Because
the via holes 41 are formed through a thin silicon substrate rather
than a glass substrate, it is possible to form them using a simple
ICP-etching process rather than a difficult sandblasting process in
the prior art.
[0049] Then, Au is filled in the via holes 41 through a sputtering
process, so that external electrode pads are formed to be
electrically connected with the internal extrude pads 20 through
the via holes 41 as shown in FIG. 3G. At this time, it is also
possible to reduce the sputtering time because the thickness of the
closure substrate 40 is thin.
[0050] As described above, because it is possible to provide a
light, thin and miniaturized package according to the present
invention, an apparatus, to which this package is applied, can be
also miniaturized.
[0051] In addition, because it is possible to provide a package
stable and highly reliable in function, the improvement in
reliability and quality of an apparatus which employs the package
can be realized.
[0052] Moreover, because a package can be manufactured with a
stable and simple process, it is possible to improve yield and to
save costs.
[0053] Although an exemplary embodiment of the present invention
has been shown and described in order to exemplify the principle of
the present invention, the present invention is not limited to the
specific exemplary embodiment. It will be understood that various
modifications and changes can be made by one skilled in the art
without departing from the spirit and scope of the invention as
defined by the appended claims. For example, the present invention
can be applied to a package for a highly integrated device beyond a
MEMS device. Therefore, it shall be considered that such
modifications, changes and equivalents thereof are all included
within the scope of the present invention.
* * * * *