U.S. patent application number 11/069999 was filed with the patent office on 2005-08-11 for fbar based duplexer device and manufacturing method thereof.
This patent application is currently assigned to SAMSUNG ELECTRO-MECHANICS CO., LTD.. Invention is credited to Kwon, Jong Oh, Sunwoo, Kook Hyun.
Application Number | 20050174193 11/069999 |
Document ID | / |
Family ID | 34374216 |
Filed Date | 2005-08-11 |
United States Patent
Application |
20050174193 |
Kind Code |
A1 |
Sunwoo, Kook Hyun ; et
al. |
August 11, 2005 |
FBAR based duplexer device and manufacturing method thereof
Abstract
Disclosed herein is an FBAR based duplexer device and a
manufacturing method thereof, which can achieve miniaturization,
and reduction of a manufacturing cost and enhancement of a yield
due to a simplified process. According to the present invention,
first, a plurality of FBAR chips are prepared. Each of the FBAR
chips comprises a substrate, air gaps and piezoelectric layer unit,
which are successively arranged, a plurality of electrode pads
electrically connected to the piezoelectric layer unit, and bump
balls formed on the electrode pads in a one to one ratio. Then, a
duplexer substrate having a duplexing circuit is prepared, and a
plurality of the FBAR chips come into contact with the duplexer
substrate. In this state, they are reversed so that the substrates
of the FBAR chips face upward, and the bump balls are bonded to the
duplexer substrate. After that, protective structures are formed by
the use of a film, so as to be positioned on side surfaces as well
as upper surface of the respective FBAR chips, and finally, a
molding portion is formed so as to cover the protective
structures.
Inventors: |
Sunwoo, Kook Hyun;
(Taean-gun, KR) ; Kwon, Jong Oh; (Suwon,
KR) |
Correspondence
Address: |
LOWE HAUPTMAN GILMAN AND BERNER, LLP
1700 DIAGONAL ROAD
SUITE 300 /310
ALEXANDRIA
VA
22314
US
|
Assignee: |
SAMSUNG ELECTRO-MECHANICS CO.,
LTD.
|
Family ID: |
34374216 |
Appl. No.: |
11/069999 |
Filed: |
March 3, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11069999 |
Mar 3, 2005 |
|
|
|
10754578 |
Jan 12, 2004 |
|
|
|
Current U.S.
Class: |
333/133 |
Current CPC
Class: |
H01L 2224/48091
20130101; H01L 23/3107 20130101; H03H 9/706 20130101; H03H 3/02
20130101; H01L 2924/3025 20130101; H03H 9/0571 20130101; H01L
2224/48091 20130101; H01L 2924/00014 20130101; H01L 2924/3025
20130101; H01L 2924/00 20130101 |
Class at
Publication: |
333/133 |
International
Class: |
H03H 009/70 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 2003 |
KR |
2003-67412 |
Claims
1-6. (canceled)
7. An FBAR based duplexer device comprising: a PCB substrate having
a duplexing circuit; a plurality of FBAR chips, each comprising an
FBAR chip substrate, an air gap defined at a lower surface of the
FBAR chip substrate, a piezoelectric layer unit formed under the
air gap, a plurality of electrode pads provided at a lower side of
the FBAR chip substrate so as to be electrically connected to the
piezoelectric layer unit, and a plurality of bump balls formed on a
lower side of the electrode pads so as to be bonded to an upper
surface of the PCB substrate; protective structures made of a film,
the protective structures being laminated on the PCB substrate so
as to cover side surfaces and upper surfaces of the respective FBAR
chips; and a molding portion formed on the PCB substrate so as to
completely cover the protective structures.
8. The device as set forth in claim 7, wherein the protective
structures are made of an insulation film including a
photosensitive polymer film and a non-photosensitive polymer film,
and laminated on the PCB substrate by using a vacuum deposition.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a duplexer device
implemented by using a film bulk acoustic resonator (hereinafter,
referred to as an FBAR), and a manufacturing method thereof, and
more particularly to an FBAR based duplexer device, and a
manufacturing method thereof, which can achieve miniaturization,
and reduction of a manufacturing cost and enhancement of a yield
due to a simplified process.
[0003] 2. Description of the Related Art
[0004] In recent years, wireless communication devices have tended
to become much leaner, and enhanced and diversified in their
quality and functions due to the development of the communication
industry. This recent trend sincerely requires miniaturization and
enhancement in quality related with various elements for use in the
wireless communication devices.
[0005] In order to satisfy such requirements to miniaturization,
therefore, currently, active development is targeting studies for
manufacturing essential components of wireless communication
devices, such as a filter and a duplexer, by using FBARs. The FBARs
are preferable for integration due to their thin film shapes, and
have good properties.
[0006] Typically, the FBARs are usually formed in such a fashion
that a piezoelectric layer is formed on a wafer, and upper and
lower electrodes are formed at the upper and lower surfaces of the
piezoelectric layer, respectively, for applying electricity to the
piezoelectric layer so as to induce oscillation thereof. Further, a
desired air gap is formed at the lower surface of the piezoelectric
layer in order to improve a resonance property of the piezoelectric
layer.
[0007] FIGS. 1A and 1B are sectional views, respectively,
illustrating different structures of conventional duplexer devices
implemented by using the FBARs formed as stated above.
[0008] The conventional FBAR based duplexer device shown in FIG. 1A
comprises at least two FBARs 12, mounted on a substrate 11 serving
as a lower support, for forming a Tx (transmitter) filter and an Rx
(receiver) filter, respectively. The substrate 11 is formed with a
common terminal and transmission/receiving terminals, and circuit
patterns for electrically connecting the terminals to the Tx and Rx
filters implemented by the FBARs. After the FBARs 12 are
electrically connected to the circuit patterns formed at the
substrate 11, in order to achieve a complete sealing of all of the
FBARs 12, a molding portion 13 is formed on the substrate 11 by the
use of certain sealing material.
[0009] As the substrate 11, due to the complexity of implemented
circuits thereof, printed circuit board (PCB) type or low
temperature co-fired ceramic (LTCC) type substrates are mainly
used, but the PCB substrates are more preferable since they have
many advantages, such as a low price, good properties and high
productivity. In case of using the PCB substrates, as shown in FIG.
1A, it is necessary to provide certain protective structures on the
FBARs 12, respectively, for protecting device functional portions,
that is, piezoelectric layers, air gaps, and electrode layers, of
the FBARs 12 from a molding process. These protective structures
may be formed, for example, by processing a wafer having a certain
thickness according to a wafer level package (WLP) technique, and
bonding the processed wafer onto a substrate wafer of the
corresponding FBAR.
[0010] In case that the FBARs 12 are formed with the protective
structures, respetively, as stated above, however, the overall
structure and manufacturing process of the FBARs 12 are
disadvantageously complex, since the protective structures should
be configured so as to be electrically connected to the device
functional portions inside the FBARs 12, respectively, as well as
protect the device functional portions.
[0011] When an FBAR is bonded to a substrate obtained by a wafer
level package process, the obtained wafer level package type FBAR
device has a very small size of about 1 millimeter in length and
width. Due to the small size, a cap and substrate constituting the
package has a sealing area corresponding to only about 30 to 100
square micrometers, with the exception of a driving portion. Since
the FBAR device can endure only about 30.degree. C. during its
bonding process, there is a considerable restriction in a sealing
method for securing a good reliability.
[0012] Even when a large amount of the FBAR devices are produced
through any precision processes, due to a complexity in process
thereof, it is difficult to obtain an appropriate yield.
[0013] In case that an LTCC technique is adopted in order to
eliminate the above problems, as shown in FIG. 1B, first, a
plurality of ceramic sheets are vertically laminated so as to form
an LTCC substrate 15, which is defined therein with a cavity, and
then a plurality of FBARs 16 are mounted inside the cavity defined
in the LTCC substrate 15. After electrically connecting the FBARs
16 to the substrate 15 by bonding wires therebetween, a metal lead
17 is fused or seam-sealed on the LTCC substrate 15 above the FBARs
16.
[0014] In this case, since the LTCC substrate 15 is configured in
such a fashion that circuits having a duplexing function are
arranged therein in a multi-stage form, it is possible to achieve a
reduction in size, compared with the case of using a single layer
PCB substrate. Further, the LTCC substrate does not need a molding
process. Furthermore, according to the structure of the LTCC
substrate 15 as stated above, the LTCC substrate 15 already owns
certain protective structures for protecting the FBARs 16. The
protective structures are side walls obtained by defining the
cavity in the substrate 15. Therefore, the LTC substrate 15 does
not need separate protective structures. That is, the FBARs 16 only
comprise an air gap, piezoelectric layer and electrode layers
vertically arranged in series on an FBAR substrate wafer.
[0015] The LTCC technique, however, causes torsion of the LTCC
substrate 15 during a LTCC firing process, resulting in a serious
leak problem due to inferior bonding between the lead 17 and the
LTCC substrate 15. Further, due to the fact that the LTCC substrate
15 is formed by vertically laminating a plurality of the ceramic
sheets, there is a high possibility of producing any defects in the
LTCC substrate itself.
[0016] Although the above techniques have been achieved according
to a most effective method for miniaturization, since a possibility
of inferiority due to complex processes always exists, it is
difficult to secure a profit margin required for mass production,
causing an unnecessarily high manufacturing cost, and to increase a
possibility of producing inferior products due to an operator's
carelessness.
SUMMARY OF THE INVENTION
[0017] Therefore, the present invention has been made in view of
the above problems, and it is an object of the present invention to
provide an FBAR based duplexer device, and a manufacturing method
thereof, which can achieve miniaturization, and reduction of a
manufacturing cost and enhancement of a yield due to a simplified
process.
[0018] In accordance with one aspect of the present invention, the
above and other objects can be accomplished by the provision of a
method for manufacturing an FBAR based duplexer device comprising
the steps of: a) preparing a plurality of FBAR chips, each FBAR
chip comprising a substrate, air gap and piezoelectric layer unit,
which are successively arranged, a plurality of electrode pads
electrically connected to the piezoelectric layer unit, and bump
balls formed on the electrode pads in a one to one ratio; b)
preparing a duplexer substrate having a duplexing circuit; c)
reversing a plurality of the FBAR chips after contacting them with
the duplexer substrate so that the substrates of the FBAR chips
face upward, and bonding the bump balls to the duplexer substrate;
d) forming protective structures by the use of a film, the
protective structures being positioned on side surfaces as well as
an upper surface of the respective FBAR chips; and e) forming a
molding portion on the duplexer substrate so as to cover the
protective structures.
[0019] Preferably, the step a) may include the steps of: a-1)
dividing an FBAR chip substrate wafer into a plurality of wafer
sections by the use of vertical and horizontal lines, and forming a
plurality of sacrificial layer units on the divided wafer sections,
respectively; a-2) forming the piezoelectric layer units on the
sacrificial layer units, respectively; a-3) forming a plurality of
the electrode pads on each wafer section, the electrode pads being
electrically connected to the piezoelectric layer unit of the
corresponding wafer section; a-4) forming the air gaps by removing
the sacrificial layer units; a-5) forming the bump balls on the
electrode pads in a one to one ratio; and a-6) cutting the FBAR
chip substrate wafer into the divided wafer sections, thereby
obtaining a plurality of the individual FBAR chips.
[0020] Preferably, the step d) may include the steps of: d-1)
laminating a dry film on an overall surface of the duplexer
substrate and hence the FBAR chips; and d-2) removing unnecessary
portions of the dry film laminated on the duplexer substrate.
[0021] Preferably, the duplexer substrate may be made of PCB
sheets.
[0022] Preferably, the dry film may be an insulation film including
a photosensitive polymer film or a non-photosensitive polymer
film.
[0023] Preferably, the step d-2) may include the steps of: d-2-1)
exposing the unnecessary portions of the dry film to be removed to
a light, through the use of a mask; and d-2-2) removing the exposed
portions of the dry film by simultaneously applying a chemical
process using a developer solution and a physical process using
high pressure dispensing.
[0024] In accordance with another aspect of the present invention,
the above and other objects can be accomplished by the provision of
an FRAR based duplexer device comprising: a PCB substrate having a
duplexing circuit; a plurality of FBAR chips, each comprising an
FBAR chip substrate, an air gap defined at a lower surface of the
FBAR chip substrate, a piezoelectric layer unit formed under the
air gap, a plurality of electrode pads provided at a lower side of
the FBAR chip substrate so as to be electrically connected to the
piezoelectric layer unit, and a plurality of bump balls formed on a
lower side of the electrode pads so as to be bonded to an upper
surface of the PCB substrate; protective structures made of a film,
the protective structures being laminated on the PCB substrate so
as to cover side surfaces and upper surfaces of the respective FBAR
chips; and a molding portion formed on the PCB substrate so as to
completely cover the protective structures.
[0025] Preferably, the protective structures may be made of an
insulation film including a photosensitive polymer film and a
non-photosensitive polymer film, and laminated on the PCB substrate
by using a vacuum deposition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The above and other objects, features and other advantages
of the present invention will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0027] FIGS. 1A and 1B are sectional views, respectively,
illustrating conventional FBAR based duplexer devices;
[0028] FIG. 2 is a sectional view illustrating an FBAR based
duplexer device in accordance with the present invention;
[0029] FIG. 3 is a flow chart illustrating a method for
manufacturing the FBAR based duplexer device in accordance with the
present invention; and
[0030] FIGS. 4A and 4H are sectional views, respectively,
illustrating the sequential steps of manufacturing the FBAR based
duplexer device in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] Now, an FBAR based duplexer device, and a manufacturing
method thereof according to the present invention will be
described, with reference to the accompanying drawings.
[0032] As shown in FIG. 2 illustrating the sectional structure of
the FBAR based duplexer device in accordance with the present
invention, the FBAR based duplexer device of the present invention
comprises a substrate 110 serving as a lower support, a plurality
of FBAR chips 120 mounted on the substrate 110 in a flip chip
bonding manner and adapted to form Tx and Rx filters, respectively,
a plurality of protective structures, made of films, for wholly
covering the upper and side surfaces of the respective FBAR chips
120, and a molding portion 140 formed on the substrate 110 so as to
enable the protective structures 130 to be completely covered. The
substrate 110 is formed with a common terminal and
transmission/receiving terminals and circuit patterns for
electrically connecting the terminals to the Tx and Rx filters
embodied by the FBAR chips 120.
[0033] The substrate 110 may be freely selected from among various
kinds of substrates including a PCB substrate or LTCC substrate so
long as it allows the formation of circuits thereon, however, it is
more preferable to use the PCB substrate in view of cost or
productivity. In particular, the PCB substrate may be formed by
stacking a plurality of PCB sheets in a multi-layer structure, so
that the respective sheets are regularly arranged in vertical and
horizontal lines.
[0034] Each of the FBAR chips 120 comprises a certain sized FBAR
chip substrate 121 defined at the bottom portion thereof with an
air gap 122, a piezoelectric layer unit 123 formed at the lower
surface of the FBAR chip substrate 121 so as to be positioned under
the air gap 122, a plurality of electrode pads 124 formed at the
lower surface of the FBAR chip substrate 121 and adapted to be
electrically connected with the piezoelectric layer unit 123 for
performing input and output of signals, and a plurality of bump
balls 125 formed at the lower side of the electrode pads 124 in a
one to one ratio. These bump balls 125 are bonded onto the
substrate 110 of the FBAR based duplexer device.
[0035] That is, the FBAR chip 120 comprises the FBAR chip substrate
121, air gap 122, and piezoelectric layer unit 123, which are
successively arranged. After the bump balls 125 are formed,
respectively, at the electrode pads 124, which are provided so as
to be electrically connected to the piezoelectric layer unit 123,
the FBAR chip 120 is reversed so that the FBAR chip substrate 121
is located at the uppermost position. In this case, the FBAR chips
406 face upward, and the substrate 110 of the FBAR based duplexer
device faces downward.
[0036] In this case, since the FBAR chip substrate 121 is located
at the uppermost position, the FBAR chip substrate 121 can serve as
an upper cover of the FBAR chip 120. Further, due to the bump balls
125 having a certain thickness, there exists a certain gap between
the duplexer substrate 110 and the piezoelectric layer unit 123 of
the FBAR chip 120.
[0037] When it is desired to form the protective structure 130 by
coating a certain dry film on the FBAR chip 120, which is mounted
on the duplexer substrate 110 in a flip chip bonding manner, the
protective structure 130 is adapted to be supported by the
substrate 121 of the FBAR chip 120. Therefore, since it is
unnecessary to form separate side walls around the FBAR chip 120,
the formation of the protective structure 130 can be achieved with
a single process.
[0038] The protective structure 130 is obtained by processing an
insulation film selected from among various kinds of insulation
films including a photosensitive polymer film or a
non-photosensitive polymer film. Since the protective structure 130
is molded and processed according to general thin-film processes
including laminating, light-exposure, developing, hardening, and
the like, it is possible to achieve precision processing thereof,
and to simplify its overall manufacturing process compared with a
wafer level package thus reducing the rate of generation of
inferior products. Further, in comparison with the wafer level
package having a complexity in its manufacturing process, a yield
and productivity thereof are improved while an overall
manufacturing cost is reduced. Furthermore, by additionally
performing an ultraviolet exposure process in a state wherein a
certain insulation film is coated on the FBAR chip 120, it is
possible to increase the overall strength thereof.
[0039] The molding portion 140 of the FBAR based duplexer device is
obtained by applying a sealing material and the like on the
duplexer substrate 110 so as to completely cover all of the FBAR
chips 120, and hardening the applied sealing material.
[0040] As stated above, since the FBAR chip of the present
invention comprises a certain protective space for securing the
normal function of the piezoelectric layer unit 123 and the like by
virtue of the thickness of the bump balls 125, and the protective
structure 130, made of an insulation film, seals the certain
protective space from the outside, the FBAR chip 120 can be
protected from any external stimulations generated during the
formation of the molding portion 140.
[0041] FIG. 3 is a flow chart illustrating a method for
manufacturing the FBAR based duplexer device in accordance with the
present invention.
[0042] FIGS. 4A and 4H are sectional views, respectively,
illustrating the sequential steps of manufacturing the FBAR based
duplexer device in accordance with an embodiment of the present
invention.
[0043] Now, a manufacturing method of the FBAR based duplexer
device in accordance with the present invention will be explained
with reference to FIGS. 3, and 4A to 4H.
[0044] For manufacturing the FBAR based duplexer device of the
present invention, first, there is provided an FBAR chip wafer
comprising a plurality of air gaps, piezoelectric layer units, and
electrode pads, which are arranged at regular distances (step
301).
[0045] Referring to FIG. 4A, the FBAR chip wafer, designated as
reference numeral 401, is formed with air gaps 402, piezoelectric
layer units 403, and electrode pads 404. These air gaps 402,
piezoelectric layer units 403, and electrode pads 404 can be formed
by using various known methods. For example, an FBAR chip wafer
having a certain area is first divided into a plurality of wafer
sections by the use of vertical and horizontal lines, and the
respective wafer sections are formed with sacrificial layer units,
respectively. Then, piezoelectric layer units are formed on the
sacrificial layer units, respectively, and subsequently a plurality
of electrode pads are formed on each wafer section so as to be
electrically connected to the piezoelectric layer unit provided on
the wafer section. After that, the sacrificial layer units are
removed so as to form air gaps, which are vertically aligned with
the piezoelectric layer units.
[0046] Referring to FIG. 4B, on the electrode pads 404 of the FBAR
chip wafer 401 are formed bump balls 405, respectively (step
302).
[0047] As can be seen from the above description, the formation of
the bump balls 405 at the level of the FBAR chip wafer 401 can be
achieved through a single process, regardless of the number of the
FBAR chips. This is more advantageous than a conventional method
wherein the bump balls are formed at individual FBAR chips,
respectively.
[0048] After that, as shown in FIG. 4C, the FBAR chip wafer 401,
which is formed with the air gaps 402, piezoelectric layer units
403, electrode pads 404 and bump balls 405, is cut along
predetermined vertical and horizontal cutting lines as boundary
lines between the divided wafer sections, thereby forming a
plurality of individual FBAR chips 406 (step 303).
[0049] When a plurality of the FBAR chips 406 having a desired
resonance property are prepared according to the above steps 301 to
303, the FBAR chips 406 are reversed at their original positions,
thereby allowing their bump balls 405 to. be bonded to a duplexer
substrate 407 (step 304). In this state, the bump balls 405 of the
FBAR chips 406 face downward, and their FBAR chip wafers 401 face
upward. FIG. 4D illustrates the FBAR chips 406 bonded to the
duplexer substrate 407 in a flip chip bonding manner.
[0050] Upon completion of such flip chip bonding, as shown in FIG.
4E, a dry film 408 is laminated over the duplexer substrate 407 and
hence a plurality of the FBAR chips 406 (step 305). In this case,
as the laminating process is performed by the use of a vacuum
laminator, the dry film 408 can be coated over the side surfaces as
well as upper surfaces of the FBAR chips 406.
[0051] Then, as shown in FIG. 4F, certain portions of the laminated
dry film 408, located on the duplexer substrate 407, are removed so
as to expose portions of the electrode pads 404 to the outside,
through the use of a mask (step 306). In this case, for the removal
of the exposed portions of the dry film 408, a chemical process
using a developer solution and a physical process using a high
pressure dispensing may be simultaneously applied.
[0052] The duplexer substrate 407 undergoes a dicing process as
shown in FIG. 4G, thereby achieving the removal of any frequencies
and other factors effecting properties of a resultant duplexer
device. Subsequently, the duplexer substrate 407 is exposed to
ultraviolet rays, so as to allow a film 409 laminated thereon to be
hardened (step 307).
[0053] Finally, as a certain sealing material is molded and
hardened on the diced duplexer substrate 407, the FBAR based
duplexer device packaged as shown in FIG. 4H is manufactured (step
308).
[0054] As apparent from the above description, the present
invention provides an FBAR chip comprising a protective space via
the use of a dry film and a flip chip bonding manner, resulting in
an enhancement in a sealing degree compared with conventional
techniques. Further, according to the present invention, the FBAR
chip comprises a protective structure, which is configured in such
a fashion that its side surfaces and upper surface are
simultaneously formed with a single process, thereby achieving a
simplification in a manufacturing process thereof thus increasing a
yield while reducing overall manufacturing cost.
[0055] Although the preferred embodiments of the present invention
have been disclosed for illustrative purposes, those skilled in the
art will appreciate that various modifications, additions and
substitutions are possible, without departing from the scope and
spirit of the invention as disclosed in the accompanying
claims.
* * * * *