U.S. patent application number 17/135622 was filed with the patent office on 2021-04-22 for acoustic wave resonator with laser-drilled vias.
The applicant listed for this patent is Skyworks Solutions, Inc.. Invention is credited to Mitsuhiro Furukawa, Takeshi Furusawa, Atsushi Takano.
Application Number | 20210119607 17/135622 |
Document ID | / |
Family ID | 1000005311383 |
Filed Date | 2021-04-22 |
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United States Patent
Application |
20210119607 |
Kind Code |
A1 |
Takano; Atsushi ; et
al. |
April 22, 2021 |
ACOUSTIC WAVE RESONATOR WITH LASER-DRILLED VIAS
Abstract
A packaged acoustic wave component is disclosed. The packaged
acoustic wave component can include a first acoustic wave resonator
that includes a first interdigital transducer electrode that is
positioned over a first piezoelectric layer. The packaged acoustic
wave component can also include a second acoustic wave resonator
including a second interdigital transducer electrode positioned
over a second piezoelectric layer. The second piezoelectric layer
is bonded to the first piezoelectric layer. The packaged acoustic
wave component can further include a stopper structure that is
positioned over the first piezoelectric layer. The first stopper
structure is positioned above a via and extends through the first
piezoelectric layer. The stopper structure is in electrical
communication with the first interdigital transducer electrode and
includes a material which reflects at least fifty percent of light
having a wavelength of 355 nanometers.
Inventors: |
Takano; Atsushi; (Kadoma -
Shi, JP) ; Furukawa; Mitsuhiro; (Nishinomiya - Shi,
JP) ; Furusawa; Takeshi; (Toyonaka - Shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Skyworks Solutions, Inc. |
Woburn |
MA |
US |
|
|
Family ID: |
1000005311383 |
Appl. No.: |
17/135622 |
Filed: |
December 28, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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17034810 |
Sep 28, 2020 |
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17135622 |
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62907255 |
Sep 27, 2019 |
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62907264 |
Sep 27, 2019 |
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62907290 |
Sep 27, 2019 |
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62907329 |
Sep 27, 2019 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H03H 3/08 20130101; H03H
9/02574 20130101; H03H 9/145 20130101; H03H 9/25 20130101; H03H
9/6406 20130101 |
International
Class: |
H03H 9/25 20060101
H03H009/25; H03H 9/02 20060101 H03H009/02; H03H 9/145 20060101
H03H009/145; H03H 9/64 20060101 H03H009/64; H03H 3/08 20060101
H03H003/08 |
Claims
1. An acoustic wave component comprising: a piezoelectric layer; an
interdigital transducer electrode over the piezoelectric layer; a
stopper structure in electrical communication with the interdigital
transducer electrode, the stopper structure including a material
which reflects at least fifty percent of light having a wavelength
of 355 nanometers; and a via extending through the piezoelectric
layer to the stopper structure.
2. The acoustic wave component of claim 1 wherein the via is
laser-drilled.
3. The acoustic wave component of claim 1 wherein the via has a
frustoconical shape.
4. The acoustic wave component of claim 1 wherein the stopper
structure includes a material which reflects at least seventy-five
percent of light having a wavelength of 355 nanometers.
5. The acoustic wave component of claim 1 wherein the stopper
structure has a thickness of less than 5 micrometers.
6. The acoustic wave component of claim 1 wherein the stopper
structure has a thickness of more than 1 micrometer.
7. The acoustic wave component of any of claims 1 wherein a
thickness of the stopper structure is less than twenty-two percent
of a thickness of the piezoelectric layer.
8. The acoustic wave component of claim 1 wherein a thickness of
the stopper structure is less than four percent of the thickness of
the piezoelectric layer.
9. The acoustic wave component of claim 1 wherein a thickness of
the stopper structure is at least one percent of the thickness of
the piezoelectric layer.
10. The acoustic wave component of any of claim 1 further
comprising an interconnect layer in electrical communication with
the interdigital transducer electrode and the stopper structure
wherein the stopper structure is located between the piezoelectric
layer and a portion of the interconnect layer.
11. An acoustic wave component comprising: a piezoelectric layer;
an interdigital transducer electrode over a first surface of the
piezoelectric layer; a stopper structure over the first surface of
the piezoelectric layer and in electrical communication with the
interdigital transducer electrode, the stopper structure including
aluminum; a via extending through a portion of the piezoelectric
layer covered by the stopper structure; and a conductive structure
extending into the via and in contact with the stopper
structure.
12. The acoustic wave component of claim 11 wherein the via is a
laser-drilled via.
13. The acoustic wave component of claim 11 wherein the via has a
frustoconical shape.
14. The acoustic wave component of claim 11 wherein the conductive
structure extends over at least a portion of a second surface of
the piezoelectric layer opposite the first surface of the
piezoelectric layer.
15. The acoustic wave component of claim 11 further comprising an
interconnect layer in electrical communication with the
interdigital transducer electrode and the stopper structure wherein
the stopper structure is located between the piezoelectric layer
and the interconnect layer.
16. The acoustic wave component of claim 11 wherein a thickness of
the stopper structure is less than four percent of a thickness of
the piezoelectric layer.
17. The acoustic wave component of claim 11 wherein the stopper
structure has a thickness of less than 5 micrometers.
18. The acoustic wave component of claim 11 wherein a thickness of
the stopper structure is less than four percent of the thickness of
the piezoelectric layer.
19. The acoustic wave component of claim 11 wherein a thickness of
the stopper structure is at least one percent of the thickness of
the piezoelectric layer.
20. The acoustic wave component of claim 11 wherein the stopper
structure includes a material which reflects at least seventy-five
percent of light having a wavelength of 355 nanometers.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] Any and all applications for which a foreign or domestic
priority claim is identified in the Application Data Sheet, or any
correction thereto, are hereby incorporated by reference under 37
CFR 1.57.
BACKGROUND
Technical Field
[0002] Embodiments of this disclosure relate to acoustic wave
resonators.
Description of Related Technology
[0003] Acoustic wave filters can be implemented in radio frequency
electronic systems. For instance, filters in a radio frequency
front end of a mobile phone can include acoustic wave filters. An
acoustic wave filter can filter a radio frequency signal. An
acoustic wave filter can be a band pass filter. A plurality of
acoustic wave filters can be arranged as a multiplexer. For
example, two acoustic wave filters can be arranged as a
duplexer.
[0004] An acoustic wave filter can include a plurality of
resonators arranged to filter a radio frequency signal. Example
acoustic wave filters include surface acoustic wave (SAW) filters
and bulk acoustic wave (BAW) filters. A surface acoustic wave
resonator can include an interdigital transductor electrode on a
piezoelectric substrate. The surface acoustic wave resonator can
generate a surface acoustic wave on a surface of the piezoelectric
layer on which the interdigital transductor electrode is
disposed.
SUMMARY OF CERTAIN INVENTIVE ASPECTS
[0005] The innovations described in the claims each have several
aspects, no single one of which is solely responsible for its
desirable attributes. Without limiting the scope of the claims,
some prominent features of this disclosure will now be briefly
described.
[0006] In one aspect, a packaged acoustic wave component is
disclosed. The packaged acoustic wave component can include a first
acoustic wave resonator that includes a first interdigital
transducer electrode that is positioned over a first piezoelectric
layer. The Packaged acoustic wave component can also include a
second acoustic wave resonator that includes a second interdigital
transducer electrode that is positioned over a second piezoelectric
layer. The second piezoelectric layer is bonded to the first
piezoelectric layer. The packaged acoustic wave component can
further include a stopper structure that is positioned over the
first piezoelectric layer. The first stopper structure is
positioned above a via that extends through the first piezoelectric
layer. The stopper structure is in electrical communication with
the first interdigital transducer electrode and includes a material
which reflects at least fifty percent of light having a wavelength
of 355 nanometers.
[0007] In an embodiment, the via is a laser-drilled via.
[0008] In an embodiment, the packaged acoustic wave component
further includes a second stopper structure that is positioned over
the first piezoelectric layer. The second stopper structure can be
positioned over a second laser-drilled via extending through the
first piezoelectric layer. The second stopper structure can be in
electrical communication with the second interdigital transducer
electrode. The second stopper structure can include a material
which reflects at least fifty percent of light having a wavelength
of 355 nanometers.
[0009] In an embodiment, the packaged acoustic wave component
further includes an interconnect layer that is in electrical
communication with the first interdigital transducer electrode and
the stopper structure. The interconnect layer can be positioned
over at least a portion of the stopper structure.
[0010] In an embodiment, the packaged acoustic wave component
further includes an interconnect structure that extends between the
first piezoelectric layer and the second piezoelectric layer. The
interconnect structure can be in electrical communication with the
second interdigital transducer electrode and the second stopper
structure. The interconnect structure can be positioned over at
least a portion of the second stopper structure.
[0011] In an embodiment, the packaged acoustic wave component
further includes a wall surrounding a region including the first
and second acoustic wave resonators. The wall can bond the first
piezoelectric layer to the second piezoelectric layer to form a
package structure. At least one of the stopper structure or the
second stopper structure can be located within the region
surrounded by the wall.
[0012] In an embodiment, at least one of the stopper structure or
second stopper structure includes a material which reflects at
least seventy-five percent reflective of light having a wavelength
of 355 nanometers.
[0013] In an embodiment, at least one of the stopper structure or
second stopper structure is an aluminum layer.
[0014] In an embodiment, at least one of the stopper structure or
second stopper structure has a thickness of less than 5
micrometers.
[0015] In an embodiment, the first and second piezoelectric layers
are separated by a gap of 30 micrometers or less.
[0016] In an embodiment, an overall thickness of the packaged
acoustic wave component is less than 200 micrometers.
[0017] In an embodiment, the first and second piezoelectric layers
are lithium tantalate layers.
[0018] In an embodiment, the first and second piezoelectric layers
are lithium niobate layers.
[0019] In one aspect, a packaged acoustic wave component is
disclosed. The packaged acoustic wave component can include a first
acoustic wave resonator that includes a first interdigital
transducer electrode that is positioned over a first piezoelectric
layer. The packaged acoustic wave component can also include a
second acoustic wave resonator that includes a second interdigital
transducer electrode that is positioned over a second piezoelectric
layer. The second piezoelectric layer is bonded to the first
piezoelectric to form a package that encapsulates the first and
second interdigital transducer electrodes. The packaged acoustic
wave component can further include a stopper structure that is
positioned over the first piezoelectric layer. The stopper
structure that is positioned over a via that extends through the
first piezoelectric layer. The stopper structure includes
aluminum.
[0020] In an embodiment, the via is a laser-drilled via.
[0021] In an embodiment, the packaged acoustic wave component
further includes a first conductive structure that extends into the
via. The first conductive structure can be in electrical
communication with the first interdigital transducer electrode.
[0022] In an embodiment, the packaged acoustic wave component
further includes a second stopper structure that is positioned over
the first piezoelectric layer. The second stopper structure can be
positioned over a second laser-drilled via that extends through the
first piezoelectric layer. The stopper structure and second stopper
structure can include aluminum. The packaged acoustic wave
component can further include a second conductive structure that
extends into the second via. The second conductive structure can be
in electrical communication with the second interdigital transducer
electrode. The packaged acoustic wave component can further
includes an interconnect structure that extends between the first
piezoelectric layer and the second piezoelectric layer. The
interconnect structure can be in electrical communication with the
second interdigital transducer electrode and the second stopper
structure. The interconnect structure can be positioned over at
least a portion of the second stopper structure.
[0023] In an embodiment, the packaged acoustic wave component
further includes an interconnect layer that is in electrical
communication with the first interdigital transducer electrode and
the stopper structure. The interconnect layer can be positioned
over at least a portion of the stopper structure.
[0024] In an embodiment, the packaged acoustic wave component
further includes a wall that bonds a region that includes the first
and second acoustic wave resonators. The wall can also bond the
first piezoelectric layer to the second piezoelectric layer to form
a package.
[0025] In an embodiment, the stopper structure has a thickness of
less than 5 micrometers.
[0026] In an embodiment, the first and second piezoelectric layers
are separated by a gap of 30 micrometers or less.
[0027] In an embodiment, an overall thickness of the package is
less than 200 micrometers.
[0028] In an embodiment, the first acoustic wave resonator is
associated with a first frequency band, and the second acoustic
wave resonator is associated with a second frequency band. The
first frequency band can be different than the second frequency
band.
[0029] In an embodiment, a duplexer comprising the packaged
acoustic wave component disclosed herein.
[0030] In one aspect, a method of fabricating a packaged acoustic
wave component is disclosed. The method can include providing a
first acoustic wave resonator that include a first interdigital
transducer electrode on a first piezoelectric layer. The first
piezoelectric layer supports a stopper structure that includes a
material which reflects at least fifty percent of light that has a
wavelength of 355 micrometers. The method can also include
providing a second acoustic wave resonator that includes a second
interdigital transducer electrode positioned on a second
piezoelectric layer. The method can further include bonding the
first piezoelectric layer to the second piezoelectric layer to form
a package structure that encapsulates the first and second
interdigital transducer electrodes. The method can further include
forming a via by applying laser light to an outside surface of the
first piezoelectric layer at a location opposite the stopper
structure. The via extends through the first piezoelectric layer
and exposing a portion of the stopper structure.
[0031] In an embodiment, the first piezoelectric layer further
supports a second stopper structure including a material which
reflects at least fifty percent of light having a wavelength of 355
micrometers.
[0032] In an embodiment, the method further includes applying laser
light to the outside surface of the second piezoelectric layer at a
location opposite the second stopper structure to form a second
laser-drilled via extending through the first piezoelectric layer
and exposing a portion of the second stopper structure. The first
piezoelectric layer can further support an interconnect structure
in contact with the second stopper structure, and the second
stopper structure is located between the interconnect structure and
the first piezoelectric layer. The method can further include
forming a first conductive structure that extends into the via and
in contact with the stopper structure and a second conductive
structure that extends into the second via and in contact with the
second stopper structure. Bonding the first piezoelectric layer to
the second piezoelectric layer can include bonding an upper surface
of the interconnect structure to an interconnect bond pad that is
positioned over the second piezoelectric layer and in electrical
communication with the second interdigital transducer
electrode.
[0033] In an embodiment, the first piezoelectric layer further
supports an interconnect layer that is in electrical communication
with the first interdigital transducer electrode and the stopper
structure. The stopper structure can be located between the first
piezoelectric layer and the interconnect layer.
[0034] In an embodiment, the first piezoelectric layer further
supports a wall structure surrounding the first acoustic wave
resonator and the stopper structure in a plan view. Bonding the
first piezoelectric layer to the second piezoelectric layer can
include bonding an upper surface of the wall structure to a wall
bond pad that is positioned over the second piezoelectric layer and
surrounding the second acoustic wave resonator.
[0035] In an embodiment, the first acoustic wave resonator is
associated with a first frequency band and wherein the second
acoustic wave resonator is associated with a second frequency band.
The first frequency band can be different than the second frequency
band.
[0036] In one aspect, a method of fabricating a packaged acoustic
wave component is disclosed. The method can include providing a
first acoustic wave resonator component that includes a first
piezoelectric layer. The first piezoelectric layer supports a
stopper structure and a first interdigital transducer electrode.
The stopper structure including aluminum. The method can also
include providing a second acoustic wave resonator component that
includes a second piezoelectric layer that supports a second
interdigital transducer electrode. The method can further include
bonding the first piezoelectric layer to the second piezoelectric
layer to form a package encapsulating the first and second
interdigital transducer electrodes. The can method further include
forming a via by applying laser light to an outside surface of the
first piezoelectric layer at a location opposite the stopper
structure. The via extends through the first piezoelectric layer
and exposes a portion of the stopper structure.
[0037] In an embodiment, the first piezoelectric layer further
supports a second stopper structure including aluminum. The method
can further include applying laser light to the outside surface of
the second piezoelectric layer at a location opposite the second
stopper structure to form a second laser-drilled via that extends
through the first piezoelectric layer and exposes a portion of the
second stopper structure. The first piezoelectric layer can further
support an interconnect structure that is in contact with the
second stopper structure. The second stopper structure can be
located between the interconnect structure and the first
piezoelectric layer. Bonding the first piezoelectric layer to the
second piezoelectric layer can comprise bonding an upper surface of
the interconnect structure to an interconnect bond pad that is
positioned over the second piezoelectric layer and in electrical
communication with the second interdigital transducer
electrode.
[0038] In an embodiment, the method further includes forming a
first conductive structure that extends into the via and in contact
with the stopper structure.
[0039] In an embodiment, the first acoustic wave resonator is
associated with a first frequency band, and the second acoustic
wave resonator is associated with a second frequency band. The
first frequency band is different than the second frequency
band.
[0040] In an embodiment, the first and second piezoelectric layers
are lithium tantalate layers.
[0041] In an embodiment, the first and second piezoelectric layers
are lithium niobate layers.
[0042] In one aspect, an acoustic wave component is disclosed. The
acoustic wave component can include a piezoelectric layer, an
interdigital transducer electrode positioned over the piezoelectric
layer, a stopper structure that is in electrical communication with
the interdigital transducer electrode, and a via extending through
the piezoelectric layer to the stopper structure. The stopper
structure includes a material which reflects at least fifty percent
of light having a wavelength of 355 nanometers.
[0043] In an embodiment, the stopper structure includes a material
which reflects at least seventy-five percent of light having a
wavelength of 355 nanometers.
[0044] In an embodiment, the stopper structure is an aluminum
layer.
[0045] In an embodiment, the stopper structure has a thickness of
less than 15 micrometers. The stopper structure can have a
thickness of less than 5 micrometers. The stopper structure can
have a thickness of more than 1 micrometer.
[0046] In an embodiment, a thickness of the stopper structure is
less than twenty-two percent of a thickness of the piezoelectric
layer. The thickness of the stopper structure can be less than four
percent of the thickness of the piezoelectric layer. The thickness
of the stopper structure can be at least one percent of the
thickness of the piezoelectric layer.
[0047] In an embodiment, the via is laser-drilled.
[0048] In an embodiment, the via has a frustoconical shape.
[0049] In an embodiment, the acoustic wave component further
includes an interconnect layer that is in electrical communication
with the interdigital transducer electrode and the stopper
structure. The stopper structure can be located between the
piezoelectric layer and a portion of the interconnect layer. The
interconnect layer can be a copper layer.
[0050] In an embodiment, the acoustic wave component further
includes a conductive structure that extends into the via and in
electrical communication with the stopper structure.
[0051] In an embodiment, the piezoelectric layer is a lithium
tantalate layer.
[0052] In an embodiment, the piezoelectric layer is a lithium
niobate layer.
[0053] In one aspect, an acoustic wave component is disclosed. the
acoustic wave component can include a piezoelectric layer, an
interdigital transducer electrode positioned over a first surface
of the piezoelectric layer, a stopper structure positioned over the
first surface of the piezoelectric layer and in electrical
communication with the interdigital transducer electrode, a via
that extends through a portion of the piezoelectric substrate that
is covered by the stopper structure, and a conductive structure
that extends into the via and in contact with the stopper
structure. The stopper structure includes aluminum.
[0054] In an embodiment, the via is a laser-drilled via.
[0055] In an embodiment, the conductive structure extends over at
least a portion of a second surface of the piezoelectric layer
opposite the first surface of the piezoelectric layer.
[0056] In an embodiment, the acoustic wave component further
includes an interconnect layer that is in electrical communication
with the interdigital transducer electrode and the stopper
structure. The stopper structure can be located between the
piezoelectric layer and the interconnect layer.
[0057] In an embodiment, a thickness of the stopper structure is
less than four percent of a thickness of the piezoelectric
layer.
[0058] In an embodiment, the stopper structure has a thickness of
less than 5 micrometers.
[0059] In an embodiment, the piezoelectric layer is a lithium
tantalate layer.
[0060] In an embodiment, the piezoelectric layer is a lithium
niobate layer.
[0061] In one aspect, a method of fabricating an acoustic wave
component is disclosed. The method can include forming a stopper
structure over a piezoelectric layer. The stopper structure
includes a material which reflects at least fifty percent of light
having a wavelength of 355 nanometers. The method can also include
forming an interdigital transducer electrode over the piezoelectric
layer. The interdigital transducer layer is electrically connected
to the stopper structure. The method can further include forming a
via by applying laser light to the piezoelectric layer on a side of
the piezoelectric layer opposite the stopper structure. The via
extends through the piezoelectric layer and exposes a portion of
the stopper structure.
[0062] In an embodiment, the method further includes forming a
conductive structure that extends into the via and in contact with
the stopper structure.
[0063] In an embodiment, the method further includes forming an
interconnect structure that is in electrical communication with the
stopper structure and the interdigital transducer electrode. At
least a portion of the interconnect structure can extend over the
stopper structure.
[0064] In an embodiment, the stopper structure includes a material
which reflects at least seventy-five percent of light having a
wavelength of 355 nanometers.
[0065] In an embodiment, the stopper structure is an aluminum
layer.
[0066] In an embodiment, the stopper structure has a thickness of
less than 5 micrometers.
[0067] In an embodiment, the method further includes using an
endpoint detector while applying laser light to the piezoelectric
layer to detect exposure of the stopper structure to the etching
laser.
[0068] In an embodiment, the piezoelectric layer is a lithium
tantalate layer.
[0069] In an embodiment, the piezoelectric layer is a lithium
niobate layer.
[0070] In one aspect, a method of fabricating an acoustic wave
component is disclosed. The method can include forming a stopper
structure over a piezoelectric layer. The stopper structure
includes aluminum. The method can also include forming an
interdigital transducer electrode over the piezoelectric layer. The
interdigital transducer electrode is electrically connected to the
stopper structure. The method can further include forming a via by
applying laser light to the piezoelectric layer on a side of the
piezoelectric layer opposite the stopper structure. The via extends
through the piezoelectric layer and exposes a portion of the
stopper structure.
[0071] In an embodiment, the method further includes forming a
conductive structure that extends into the via and in contact with
the stopper structure.
[0072] In an embodiment, the method further comprises forming an
interconnect structure that is in electrical communication with the
stopper structure and the interdigital transducer electrode. At
least a portion of the interconnect structure can extend over the
stopper structure.
[0073] In an embodiment, the method further includes using an
endpoint detector while applying laser light to the piezoelectric
layer to detect exposure of the stopper structure to the etching
layer.
[0074] In an embodiment, the stopper structure has a thickness of
less than 5 micrometers.
[0075] In one aspect, a method of fabricating an acoustic wave
component is disclosed. The method can include providing a
piezoelectric layer with an interdigital transducer electrode and a
stopper structure on a first side of the piezoelectric layer. The
stopper structure includes a material which reflects at least fifty
percent of light having a wavelength of 355 nanometers. The method
can also include applying laser light to a second side of a
piezoelectric layer opposite to the first side of the piezoelectric
layer to form a via through the piezoelectric layer. The via
extends through the piezoelectric layer to the stopper
structure.
[0076] For purposes of summarizing the disclosure, certain aspects,
advantages and novel features of the innovations have been
described herein. It is to be understood that not necessarily all
such advantages may be achieved in accordance with any particular
embodiment. Thus, the innovations may be embodied or carried out in
a manner that achieves or optimizes one advantage or group of
advantages as taught herein without necessarily achieving other
advantages as may be taught or suggested herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0077] Embodiments of this disclosure will now be described, by way
of non-limiting example, with reference to the accompanying
drawings.
[0078] FIGS. 1A and 1B illustrates a cross section of a surface
acoustic wave (SAW) resonator component at various stages of a
manufacturing process.
[0079] FIG. 2 illustrates a perspective view of a packaged acoustic
wave component including a first surface acoustic wave resonator
component positioned over a first wafer and a second surface
acoustic wave resonator component positioned over a second
wafer.
[0080] FIG. 3 illustrates a cross section of a packaged acoustic
wave component such as the packaged acoustic wave component of FIG.
2.
[0081] FIG. 4A is a cross section schematically illustrating the
response of a material to impingement of a laser.
[0082] FIG. 4B is a graph showing the reflection ratios of various
metals as a function of wavelength.
[0083] FIG. 5A is a top plan view schematically illustrating the
footprint of a single surface acoustic wave resonator
component.
[0084] FIG. 5B is a top plan view schematically illustrating the
footprint of a packaged acoustic wave component including a pair of
stacked resonators.
[0085] FIGS. 6A to 6E illustrate cross-sections of a portion of a
surface acoustic wave resonator component at various stages of a
manufacturing process according to an embodiment.
[0086] FIGS. 7A to 7O illustrate cross-sections of a packaged
acoustic wave component including first and second surface acoustic
wave resonator components at various stages of a manufacturing
process according to an embodiment.
[0087] FIG. 8 is a schematic diagram of a transmit filter that
includes a surface acoustic wave resonator according to an
embodiment.
[0088] FIG. 9 is a schematic diagram of a receive filter that
includes a surface acoustic wave resonator according to an
embodiment.
[0089] FIG. 10 is a schematic diagram of a radio frequency module
that includes a surface acoustic wave component according to an
embodiment.
[0090] FIG. 11 is a schematic diagram of a radio frequency module
that includes duplexers with surface acoustic wave resonators
according to an embodiment.
[0091] FIG. 12 is a schematic block diagram of a module that
includes a power amplifier, a radio frequency switch, and duplexers
that include one or more surface acoustic wave resonators according
to an embodiment.
[0092] FIG. 13 is a schematic block diagram of a module that
includes an antenna switch and duplexers that include one or more
surface acoustic wave resonators according to an embodiment.
[0093] FIG. 14 is a schematic block diagram of a wireless
communication device that includes a filter in accordance with one
or more embodiments.
[0094] FIG. 15 is a schematic block diagram of another wireless
communication device that includes a filter in accordance with one
or more embodiments.
DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS
[0095] The following description of certain embodiments presents
various descriptions of specific embodiments. However, the
innovations described herein can be embodied in a multitude of
different ways, for example, as defined and covered by the claims.
In this description, reference is made to the drawings where like
reference numerals can indicate identical or functionally similar
elements. It will be understood that elements illustrated in the
figures are not necessarily drawn to scale. Moreover, it will be
understood that certain embodiments can include more elements than
illustrated in a drawing and/or a subset of the elements
illustrated in a drawing. Further, some embodiments can incorporate
any suitable combination of features from two or more drawings.
[0096] Acoustic wave filters can filter radio frequency (RF)
signals in a variety of applications, such as in an RF front end of
a mobile phone. An acoustic wave filter can be implemented with
surface acoustic wave (SAW) resonators.
[0097] A manufacturing process of a resonator device can include a
laser drilling process to form one or more vias in a substrate,
such as a piezoelectric substrate, after the formation of resonator
structures on the opposite side of the substrate. The via can allow
electrical connections to be formed with interdigital transducer
(IDT) electrodes. In some embodiments, the vias allow connections
to be made with IDT electrodes in the interior of a package formed
by a pair of stacked resonators.
[0098] A stopper layer or stopper structure can be utilized on the
opposite side of the piezoelectric substrate to be laser drilled.
While a copper IDT electrode or a copper interconnect layer in
electrical communication with an IDT electrode can be used as a
stopper structure, the percentage of laser light absorbed by the
copper layer can be substantial. The portions of the copper layer
initially exposed by the etching layer can be exposed to a
substantial number of additional laser pulses as the remainder of
the via is drilled, to achieve its final state. The formation of a
sufficiently thick interconnect layer in the region in which the
laser via is to be formed can involve the use of expensive
deposition techniques, and can affect the thickness of a package
formed by a stacked pair of resonators.
[0099] Aspects of this disclosure relate to the use of a stopper
structure which is highly reflective to the light used in the laser
etching process. For example, a stopper layer of aluminum can be
used which is roughly six times thinner than a stopper layer made
of copper. The stopper structure may be located between the
piezoelectric substrate and an interconnect layer including a
different material, such as copper. The overall thickness of such a
layer stack can be less than the thickness of a comparatively
effective stopper layer formed entirely of copper. Because the
interconnect layer may not serve as a stopper structure, the
interconnect layer can be made thinner, and may be formed using a
wider variety of deposition techniques.
[0100] FIG. 1A illustrates a cross section of a surface acoustic
wave resonator component at a stage of a manufacturing process. The
manufacturing process may include a laser etching process. The
illustrated SAW resonator component 100 in FIG. 1A includes a
piezoelectric layer 110 and an interconnect layer 122 positioned
over a first surface the piezoelectric layer 110. The second
surface of the piezoelectric layer 110, opposite the interconnect
layer 122, is exposed to illumination 190 from an etching laser. In
some embodiments, the piezoelectric layer 110 may include a
material such as lithium tantalite (LT) or lithium niobate (LN),
and the etching layer may emit light at a wavelength of 355
nanometers (nm), suitable for laser etching of a lithium-including
piezoelectric substrate. The interconnect layer 122 may be in
electrical communication with an IDT electrode (not shown in FIG.
1A), and on the same side of the piezoelectric layer 110 as the
interconnect layer.
[0101] FIG. 1B illustrates a cross section of the surface acoustic
wave resonator component of FIG. 1A at a later stage of a
manufacturing process. Laser light has been applied to the
piezoelectric layer 110, and the laser has ablated a portion of the
piezoelectric layer 110 to form a laser-drilled via 180 extending
through the piezoelectric layer 110 and exposing a portion of the
interconnect layer 122. The laser-drilled via 180 may have a
frustoconical shape, with a wider cross-sectional dimension 182 at
the opening of the via 112, and a narrower cross-sectional
dimension 184 at the base of the via 180, adjacent the interconnect
layer 122, such that the via 180 has angled sidewalls 186.
[0102] Because of exposure to the laser illumination 190, a section
124 of the interconnect layer 122 has been ablated, melted, or
otherwise affected by exposure to the laser pulses, such that the
laser-drilled via 180 extends into the interconnect layer 122.
Although described as a section 124 of the interconnect layer 122
the section 124 may in some embodiments be a portion of an IDT
electrode itself. In some embodiments, the laser etching process
may be monitored using an endpoint detector to detect plasma
generated by ablation of the lithium-containing piezoelectric
layer. When the plasma generation tapers off, the laser etching
process may be stopped. However, there may be as many as 20 or 30
additional laser pulses emitted between the point at which the
interconnect layer 122 is first exposed and the point at which the
via 180 has been fully etched.
[0103] The interconnect layer 122 may not be directly in contact
with the piezoelectric layer 110 in the area overlying the via 180.
In various embodiments, additional layers not specifically
illustrated in FIGS. 1A and 1B may be disposed between the
interconnect layer 122 and the piezoelectric layer 110. Depending
on the thickness and composition of these layers, such layers may
have minimal effect on the laser-etching process.
[0104] In some embodiments, the overall height of a SAW resonator
may be constrained by various design considerations. For example,
SAW resonators may be provided in a stacked arrangement, with a
first SAW resonator positioned over a first surface of a first
piezoelectric substrate, and a second SAW resonator positioned over
a first surface of a second piezoelectric substrate, with the first
surfaces of the first and second substrates facing one another.
[0105] FIG. 2 illustrates a perspective view of a packaged acoustic
wave component 200 including a first surface acoustic wave
resonator component positioned over a first wafer and a second
surface acoustic wave resonator component positioned over a second
wafer. The first SAW resonator component 220a positioned over the
lower piezoelectric wafer 210a may be associated with a first
frequency band, and the second SAW resonator component 200b
positioned over the upper piezoelectric wafer 210b may be
associated with a second frequency band. Each of the SAW resonator
components 200a and 200b can include any suitable number of SAW
resonators. The packaged acoustic wave component 200 (e.g., stacked
resonator structure) may be configured to operate as a duplexer,
with one of the first SAW resonator component 220a or the second
SAW resonator component 220b configured to operate as a receive
filter, and the other configured to operate as a transmit
filter.
[0106] The lower piezoelectric wafer 210a may be wafer bonded to
the upper piezoelectric wafer 210b using any suitable wafer bonding
technique, for example, as discussed in greater detail below. The
lower piezoelectric wafer 210a and the upper piezoelectric wafer
210b may form a package enclosing the IDT electrodes of SAW
resonator component 220a and the second SAW resonator component
220b.
[0107] FIG. 3 illustrates a cross section of a packaged acoustic
wave component such as the packaged acoustic wave component of FIG.
2. The upper piezoelectric wafer 210b has a thickness of h.sub.b,
the lower piezoelectric wafer 210a has a thickness of h.sub.a, and
there is a gap 202 of thickness h.sub.g between the upper
piezoelectric wafer 210b and the lower piezoelectric wafer 210a.
The package has an overall thickness of h, where h is given by the
sum of h.sub.a, h.sub.b, and h.sub.g.
[0108] Vias 280 extend through at least one of the upper
piezoelectric wafer 210b and the lower piezoelectric wafer 210a,
allowing electrical connections to be made with the IDT electrodes
of the first SAW resonator component 220a and/or the second SAW
resonator component 220b. In the illustrated embodiment, the upper
piezoelectric wafer 210b is thicker than the lower piezoelectric
wafer 210a. In such an embodiment, the vias 280 may be formed in
the thinner lower piezoelectric wafer 210a, to facilitate formation
of the vias 280 without etching through the additional thickness of
the upper piezoelectric wafer 210b.
[0109] In the illustrated embodiment, certain of the vias 280 are
in electrical connection with the IDT electrodes of the first SAW
resonator component 220a or with a conductive structure 224 in
electrical communication with the IDT electrodes of the first SAW
resonator component 220a. Other of the vias 280 are in electrical
connection with the IDT electrodes of the second SAW resonator
component 220b via a conductive structure 226 extending between the
lower and upper piezoelectric wafers 210a and 210b. The conductive
structure 226 may be a layer of conductive material or a stack of
layers of conductive material. In some embodiments, the conductive
structure 226 may be formed by bonding a conductive structure
positioned over the upper piezoelectric wafer 210b to a conductive
structure positioned over the lower piezoelectric wafer 210a.
[0110] The conductive structures 224 and 226 serve as stopper
structures for the laser etching of the vias 280, and are of
sufficient thickness to withstand the laser etching process while
the vias 280 are being formed. In an embodiment in which the vias
280 are formed after the upper piezoelectric wafer 210b is bonded
to the lower piezoelectric wafer 210a to form a package, the
conductive structures 224 and 226 are of sufficient thickness that
the laser does not pierce the conductive structure 224 and 226 and
expose portions of the upper piezoelectric wafer 210b or the second
SAW resonator component 220b to the etching laser.
[0111] The thickness of the conductive structures 224 and 226c can
constrain the minimum thickness h.sub.g of the gap 202, and thereby
constrain a minimum overall thickness h of the package. The
thickness of the conductive structures 224 and 226 may be dependent
on a number of factors, one of which is the composition of the
conductive structures 224 and 226.
[0112] FIG. 4A is a cross section schematically illustrating the
response of a material to impingement of a laser. The material 300
is exposed to illumination 390 from an etching laser. In some
embodiments, the illumination 390 from the etching layer may be a
series of discrete pulses. A portion of the illumination 390
incident upon the material 300 is reflected as reflected radiation
392. The reflected radiation 392 may be scattered over a range of
angles, due in part to the surface conditions of the material 300
and the composition of the material 300. Another portion of the
illumination 390 may be transmitted through the material as
transmitted illumination 394. Another portion of the illumination
390 may be absorbed by the material 300 as absorbed radiation
396.
[0113] All of the illumination 390 incident upon the material 300
should be either absorbed as absorbed radiation 396, transmitted as
transmitted illumination 394, or reflected as reflected radiation
392. The respective percentages of illumination 390 absorbed as
absorbed radiation 396, transmitted as transmitted illumination
394, and reflected as reflected radiation 392 should therefore add
to 100%. For metallic materials of sufficient thickness, no
radiation should be transmitted through the material 300, and all
of the incident laser light will either be absorbed as absorbed
radiation 396 or reflected as reflected radiation 392. The
reflectivity of the material 300 to a given source of illumination
390 will therefore be directly related to the amount of
illumination 390 absorbed by the material 300.
[0114] FIG. 4B is a graph showing the reflection ratios of various
metals as a function of wavelength. Curve 410 illustrates the
reflection ratio of copper (Cu) as a function of wavelength. In
particular, at 355 nm, the reflectivity of copper is roughly 35%.
As a sufficiently thick layer of copper will not transmit light
therethrough, nearly two-thirds of light emitted at 355 nm will be
absorbed by the copper layer. The use of copper as a stopper layer
for a 355 nm etching laser can involve a layer which is thicker
than the other metals shown in the graph of FIG. 4B, as a
substantial amount of energy from the laser will be absorbed by a
copper stopper layer once the underlying layer has been etched to
expose a portion of the copper stopper layer. This absorption of
laser energy will result in melting or ablation of the stopper
layer
[0115] Curves 420 and 430 illustrate the reflection ratios of iron
(Fe) and gold (Au) as functions of wavelength. Both iron and gold
have a reflectivity of roughly 50% at 355 nm. The absorption rate
of iron or gold is roughly 75% of the absorption rate of copper.
The use of iron or gold as a stopper layer allows the use of a
stopper layer which is roughly 25% thinner than a comparatively
effective copper layer.
[0116] Curve 440 illustrates the reflection ratio of silver (Ag) as
a function of wavelength. The reflectivity of silver at 355 nm is
roughly 75%, and the absorption rate of silver at that wavelength
is roughly 38% that of the absorption rate of copper. A silver
layer used as a stopper layer may be more than 61% thinner than a
comparably effective copper layer.
[0117] Curve 440 illustrates the reflection ratio of silver (Ag) as
a function of wavelength. The reflectivity of silver at 355 nm is
roughly 75%, and the absorption rate of silver at that wavelength
is roughly 38% that of the absorption rate of copper. A silver
layer used as a stopper layer may be more than 61% thinner than a
comparably effective copper layer.
[0118] Curve 450 illustrates the reflection ratio of aluminum (Al)
as a function of wavelength. While silver is more reflective than
aluminum in the visible wavelengths, the reflectivity of aluminum
remains high for shorter wavelengths in the near-visible range,
while the reflectivity of silver drops below that of aluminum. For
light having a wavelength of 355 nm, the reflectivity of aluminum
is roughly 90%, and the absorption rate of aluminum at that
wavelength is roughly 15.4% that of copper. An aluminum layer can
therefore be 84.6% thinner than a copper stopper layer, while
providing equivalent protection for a 355 nm etching laser.
[0119] By utilizing an aluminum stopper layer, the thickness of the
stopper layer may be reduced by almost an order of magnitude. In a
package such as the package of FIGS. 2 and 3, the thickness of the
stopper layer may be a controlling factor in minimizing the
thickness h.sub.g of the gap 202 between the upper piezoelectric
wafer 210b and the lower piezoelectric wafer 210a. The thickness
h.sub.g of the gap 202, in turn, can be a controlling factor in the
overall thickness of the package. If one of the wafers is roughly
70 micrometers (um) in thickness, and the other of the wafers is
roughly 100 um in thickness, an overall package thickness of 200 um
can be provided if the thickness h.sub.g of the gap 202 is less
than 30 um.
[0120] In some embodiments, the overall footprint of a packaged
acoustic wave component including stacked resonators can be less
than the footprint of two resonators side-by-side on a single
substrate. Because of modifications to the design of the resonators
to accommodate, for example, interconnections between the lower
wafer and the upper wafer, FIG. 5A shows that a footprint 520a of a
single surface acoustic wave resonator component extends beyond the
boundaries of the functional area 510a of the resonator component
by a distance 522a. Although the functional area 510a of the
resonator component is schematically depicted as being centered
within the footprint 520a, the actual positioning of the functional
area 510a of the resonator component within the footprint 520a may
vary depending on the design of the resonator component.
[0121] In contrast, FIG. 5B shows that the footprint 520b of a
resonator component of a packaged acoustic wave component including
a stacked resonator design is larger than the footprint 520a of
FIG. 5A. In addition, it can be seen that the footprint 520b may be
wider in a lateral direction than in a longitudinal direction. The
footprint 520b of the resonator component extends beyond the
boundaries of the functional area 510b of the larger of the
resonator components by a distance 522b in a lateral direction, and
in by distance 522c in a longitudinal direction. In an embodiment
in which the lateral distance 522b is longer than the longitudinal
distance 522c, the additional length may be due to the placement of
vias extending through one of the substrates and allowing
electrical communication with each of the resonator components in
the stacked resonator package. In embodiments in which the vias are
formed in only one of the two substrates, a conductive pillar may
extend between the two substrates of the package, allowing
electrical communication with the resonator component positioned
over the upper substrate through a via formed through the lower
substrate. A package wall sealing the first substrate to the second
substrate will also increase the size of the footprint 520b.
[0122] As discussed above with respect to the resonator of FIG. 5A,
although the functional area 510b of the resonator component of
FIG. 5B is schematically depicted as being centered within the
footprint 520b, the actual positioning of the functional area 510b
of the resonator component within the footprint 520b may vary
depending on the design of the resonator component. For example, a
via providing electrical communication with the upper resonator
component may be on the opposite side of the lower resonator
component as a via providing electrical communication with the
lower resonator component, or both vias may be on the same side of
the lower resonator component.
[0123] Despite the additional size of the footprint 520b, the
stacked resonator arrangement of the packaged acoustic wave
component allows the overall footprint 520b of two resonator
components to be smaller than the total footprint of two resonator
component footprints 520a side-by-side. The total reduction in size
will vary depending on the relative size of the functional area
510b relative to the components formed in the remainder of the
footprint. In some embodiments, a reduction of at least 35% can be
achieved via a stacked resonator arrangement. In other embodiments,
a reduction of almost 45% or more can be achieved via a stacked
resonator arrangement.
[0124] While the footprint of the packaged acoustic wave component
including stacked resonators can be reduced in comparison to a
side-by-side arrangement of two resonator components, the height of
the stacked resonator components is increased. Depending on the
amount of height increase, this height increase may make a stacked
arrangement unsuitable for certain implementations. If the stacked
packaged acoustic wave component can be made sufficiently thin, the
stacked packaged acoustic wave component can be used in place of a
pair of side-by-side resonator components in certain
implementations. For example, some implementations may desire a
package thickness of less than 200 um.
[0125] If a copper stopper structure is used when forming
laser-drilled vias, the space for the thick copper stopper
structure may make achieving such a package impractical or
impossible. By using a stopper structure which is more reflective
to the illumination from a 355 nm etching laser, the specified
spacing between the package substrates may be reduced. If a
sufficiently reflective material is used as the stopper structure,
the specified spacing between the package substrates may become a
function of resonator dimensions or other package components,
rather than stopper structure dimensions.
[0126] FIGS. 6A-6E illustrate cross sections of a surface acoustic
wave resonator component at various stages of a manufacturing
process. The manufacturing process may include a laser etching
process. The illustrated SAW resonator component 600 in FIG. 6A
includes a piezoelectric layer 610 and an interconnect layer 622
positioned over a first surface the piezoelectric layer 610. The
interconnect layer 622 may be in electrical communication with an
IDT electrode (not shown in FIG. 6A) and on the same side of the
piezoelectric layer 610 as the interconnect layer 622.
[0127] The SAW resonator component 600 of FIG. 6A differs from the
SAW resonator component 100 of FIG. 1A in that the interconnect
layer 622 includes a stopper layer 628 located between the
interconnect layer 622 and the piezoelectric layer 610 in at least
one section of the interconnect layer 622. In some embodiments, the
stopper layer includes a material which is at least 50% reflective
to illumination at a wavelength of 355 nm. In some of these
embodiments, the stopper layer includes a material which is at
least 75% reflective to illumination at a wavelength of 355 nm. In
certain embodiments, the stopper layer 628 includes aluminum.
[0128] By using a stopper layer 628 that is relatively highly
reflective of laser light (e.g., an aluminum stopper layer), the
stopper layer 628 can be relatively thin compared to a less
reflective stopper layer (e.g., a copper stopper layer). For
example, the stopper layer 628 can have a thickness of less than 15
micrometers. In some instances, the stopper layer 628 can have a
thickness of less than 5 micrometers. In some instances, the
stopper layer 628 can have a thickness of less than 3 micrometers.
The stopper layer 628 can have a thickness in a range from 1
micrometer to 15 micrometers, such as in a range from 1 micrometer
to 5 micrometers. The stopper layer 628 can have a thickness that
is less than about 25% of a thickness of the piezoelectric layer
610, such as less than 22% of the thickness of the piezoelectric
layer 610. In some instances, the thickness of the stopper layer
628 is less than 4% of the thickness of the piezoelectric layer
610.
[0129] The second surface of the piezoelectric layer 610, opposite
the interconnect layer 622 and in the region of the stopper layer
628, is exposed to illumination 690 from an etching laser. As
previously discussed, the piezoelectric layer 610 may include a
material such as lithium tantalite (LT) or lithium niobate (LN),
and the etching layer may emit light at a wavelength of 355 nm,
suitable for laser etching of a lithium-including piezoelectric
substrate.
[0130] FIG. 6B illustrates a cross section of the surface acoustic
wave resonator component of FIG. 6A at a later stage of a
manufacturing process. The etching laser has ablated a portion of
the piezoelectric layer 610 to form a laser-drilled via 680
extending through the piezoelectric layer 610 and into a portion of
the stopper layer 628. However, the stopper layer 628 has prevented
the via from extending into the overlying interconnect layer 622.
The laser-drilled via 680 has a generally frustoconical shape, with
a wider cross-sectional dimension 681 at the opening of the via
680, and a narrower cross-sectional dimension 683 at the base of
the via 680, adjacent the interconnect layer 622, such that the via
680 has angled sidewalls 685.
[0131] Because of exposure to the laser illumination 190, a section
of the stopper layer 628 has been ablated, melted, or otherwise
affected by exposure to the laser pulses, such that the
laser-drilled via 680 extends into the stopper layer 628. Although
the stopper layer 628 is depicted as underlying a section of the
interconnect layer 622 the stopper layer 628 may in some
embodiments underlie a portion of an IDT electrode itself.
[0132] As previously discussed, the laser etching process may be
monitored using an endpoint detector to detect plasma generated by
ablation of the lithium-containing piezoelectric layer. When the
plasma generation tapers off, the laser etching process can be
stopped. However, there may be as many as 20 or 30 additional laser
pulses emitted between the point at which the stopper layer 628 is
first exposed and the point at which the via 680 has been fully
etched.
[0133] The stopper layer 628 may not be directly in contact with
the piezoelectric layer 610 in the area overlying the via 680. In
various embodiments, additional layers not specifically illustrated
in FIGS. 6A and 6B may be disposed between the stopper layer 628
and the piezoelectric layer 610. Depending on the thickness and
composition of these layers, such layers may have minimal effect on
the laser-etching process.
[0134] In FIG. 6C, it can be seen that a seed layer 682 has been
sputter deposited on the side of the piezoelectric layer 610
opposite the interconnect layer 622 and the stopper layer 628. In
addition, a photoresist layer 684 has been formed over the seed
layer 682, and patterned to expose a portion of the seed layer 682
covering the interior of the via 680.
[0135] In FIG. 6D, it can be seen that an interconnect structure
686 has been formed over the exposed portion of the seed layer 682,
such that the interconnect structure 686 covers at least the via
680 and the portion of the seed layer 682 immediately surrounding
the via 680. The interconnect structure 686 may be formed, for
example, by electroplating onto the seed layer 682. The
interconnect structure 686 may include copper or other suitable
conductive materials. The interconnect structure 686 may include
multiple layers of materials, such as a layer of copper followed by
a layer of tin.
[0136] In FIG. 6E, the photoresist layer 684 and the seed layer 682
have been removed, leaving the interconnect structure 686. The
interconnect structure 686 extends into the via 680, and is in
electrical communication with the interconnect layer 622 on the
opposite side of the piezoelectric layer 610, allowing
communication through the piezoelectric layer.
[0137] Similar processes can be used as part of a fabrication
process for a packaged acoustic wave component with a stacked
resonator arrangement. FIGS. 7A to 7K illustrate cross sections of
a packaged acoustic wave component at various stages of a
manufacturing process. In FIG. 7A, a surface acoustic wave (SAW)
resonator wafer 700a is provided, including a piezoelectric layer
710a having a plurality of IDT electrodes 720a formed thereon. In
some embodiments, the piezoelectric layer 710 may include any
suitable piezoelectric material such as a lithium niobate (LN)
layer or a lithium tantalate (LT) layer. As will be described in
greater detail below, the thickness of the piezoelectric layer 710a
in the provided SAW wafer 700a may not correspond to the final
thickness of the piezoelectric layer 710a in the final SAW package.
In addition, stopper structures 728a and 728b have been formed on
portions of the piezoelectric layer 710a adjacent the plurality of
IDT electrodes 720a. Additional structures not depicted in FIG. 7A
may also be formed, including electrodes in electrical
communication with the plurality of IDT electrodes 720a. Such
electrodes may include aluminum, and may be thicker than the
plurality of IDT electrodes 720a.
[0138] In some embodiments, the stopper structures 728a and 728b
each include a material which is at least 50% reflective to
illumination at a wavelength of 355 nm. In some of these
embodiments, the stopper structures 728a and 728b each include a
material which is at least 75% reflective to illumination at a
wavelength of 355 nm. In certain embodiments, the stopper
structures 728a and 728b each include aluminum.
[0139] By using stopper structures 728a and 728b that are
relatively highly reflective of laser light (e.g., aluminum stopper
structures), the stopper structures 728a and 728b can be relatively
thin compared to less reflective stopper structures (e.g., copper
stopper structures). For example, the stopper structures 728a and
728b can each have a thickness of less than 15 micrometers. In some
instances, the stopper structures 728a and 728b can each have a
thickness of less than 5 micrometers. In some instances, the
stopper structures 728a and 728b can each have a thickness of less
than 3 micrometers. The stopper structures 728a and 728b can each
have a thickness in a range from 1 micrometer to 15 micrometers,
such as in a range from 1 micrometer to 3 micrometers. The stopper
structure 728a can have a thickness that is less than about 25% of
a thickness of the piezoelectric layer 710a, such as less than 22%
of the thickness of the piezoelectric layer 710a. In some
instances, the thickness of the stopper structure 728a is less than
4% of the thickness of the piezoelectric layer 710a.
[0140] In FIG. 7B, a first photoresist layer has been deposited
over the SAW wafer 700a, and patterned via photolithography to
leave a first photoresist layer 730 extending over the IDT
electrodes 720a and stopper structures 728a and 728b, and including
apertures 732a and 732b adjacent the IDT electrode layers and
overlying the stopper structures 728a and 728b. The apertures 732a
and 732b in the first photoresist layer 730 will be used in part to
define the locations of stop structures under which laser-drilled
vias can be formed. In addition, a seed layer 734 has been formed
over the first photoresist layer 730. In some embodiments, the seed
layer 734 can include titanium (Ti), copper (Cu), or any other
suitable material. In some embodiments, the seed layer 734 can be
formed via sputter deposition, or any other suitable deposition
method.
[0141] In FIG. 7C, a second photoresist layer 740 has been formed
over the first photoresist layer 730 and the seed layer 734, and
patterned via photolithography to form inner apertures 742a and
742b, as well as an outer aperture 744 extending around the IDT
electrodes 720 and the inner apertures 742a and 742b. The inner
apertures 742a and 742b overlie the stopper structures 728a and
728b, and are aligned with the apertures 732a and 732b in the first
photoresist layer 730, but are slightly smaller, such that the seed
layer 740 on the sidewalls of the apertures 732a and 732b are
covered by portions of the second photoresist layer 740. The
apertures 732a and 732b are depicted in the illustrated embodiment
as having similar dimensions to the underlying stopper structures
728a and 728b, but in other embodiments, the stopper structures
728a and 728b may be larger or smaller in some dimensions than the
apertures 732a and 732b. The outer aperture 744 will be used in
part to define the locations of a package wall.
[0142] In FIG. 7D, additional structures have been formed within
the outer aperture 744 and the inner apertures 742a and 742b,
overlying the stopper structures 728a and 728b. An interconnect
layer 722 has been formed within inner aperture 742a, overlying the
stopper structure 728a. The interconnect layer 722 can be used to
form a connection with the IDT electrodes 720, and may extend
beyond the edge of the stopper structure 728a. A lower layer 726a
of an internal interconnect pillar has been formed within inner
aperture 742b, overlying the stopper structure 728b. A lower wall
layer 746a has been formed within the outer aperture 744. In some
embodiments, the interconnect layer 722, the lower layer 726a of
the internal interconnect pillar, and the lower wall layer 746a can
be formed via an electroplating process or other suitable process,
and can include copper or another suitable material.
[0143] In the illustrated embodiment, a third photoresist layer 760
has been formed over the second photoresist layer 740. The third
photoresist layer 760 has been patterned to form an aperture 762
exposing a section of the lower layer 726a of the internal
interconnect pillar, and to form an aperture 764 exposing a section
of the lower wall layer 746a. The third photoresist layer 760
extends over the interconnect layer 722 without exposing a portion
of the interconnect layer 722.
[0144] In FIG. 7E, a middle wall layer 746b has been formed within
the aperture 764 of the third photoresist layer 760, over the lower
wall layer 746a. A middle layer 726b of the internal interconnect
pillar has been formed within the aperture 762 of the third
photoresist layer 760, over the lower layer 726a of the internal
interconnect pillar. In the illustrated embodiment, the middle wall
layer 746b and the middle layer 726b of the internal interconnect
pillar are shown as extending to roughly the height of the upper
surface of the internal third photoresist layer 760, but in other
embodiments, the middle wall layer 746b and the middle layer 726b
of the internal interconnect pillar can extend to heights either
above or below the upper surface of the third photoresist layer
760.
[0145] In FIG. 7F, the partially fabricated resonator component has
been be planarized down to a desired height. This planarization
process has reduced the thickness of the third photoresist layer
760 as well as the thicknesses of the middle wall layer 746b and
the middle layer 726b of the internal interconnect pillar. The
middle wall layer 746b and the middle layer 726b of the internal
interconnect pillar still extend to a height greater than the
height of the interconnect layer 722, and a portion of the third
photoresist layer 760 still extends over the interconnect layer
722. By planarizing the third photoresist layer 760, the middle
wall layer 746b, and the middle layer 726b of the internal
interconnect pillar to a desired height, the overall height of the
resulting package can be reduced and/or minimized.
[0146] In FIG. 7G, an upper wall layer 746c has been formed over
the middle wall layer 746b, and an upper layer 726c of the internal
interconnect pillar has been formed over the middle layer 726b of
the internal interconnect pillar. In some embodiments, each of the
middle and upper wall layers 746b and 746c, as well as the middle
and upper layers 726b and 726c of the internal interconnect pillar
may be formed by electroplating processes. In some embodiments, the
middle layers may include the same material as the lower layers,
while the upper layers may be a different material, such as tin
(Sn) or a tin alloy, or another suitable material. Because the
interconnect layer 722 remains covered by a section of the
photoresist layer 760, no additional layer will be formed over the
interconnect layer 722 during an electroplating process.
[0147] In FIG. 7H, the photoresist layers and seed layer have been
removed to form a finished wafer which is ready for bonding to a
second wafer to form a SAW resonator package. The wall layers form
a wall 746 extending around the periphery of the SAW resonator on
finished wafer. The wall 746 has a height equal to the height of
the internal interconnect pillar 726. The interconnect layer 722
has a height which is less than the height of the wall 746 and the
internal interconnect pillar 726.
[0148] In FIG. 7I, a second SAW wafer 700b has been bonded to the
first SAW wafer 700a to form a packaged acoustic wave component 702
(e.g., a stacked SAW resonator package). In the illustrated
embodiment, the second SAW wafer 700b includes a piezoelectric
layer 710b having a plurality of IDT electrodes 720b formed
thereon. In addition, the second SAW wafer 700b has bonding pads
748a and 748b corresponding respectively to the position and
locations of the wall 746 and the internal interconnect pillar 726
of the first SAW wafer 700a. In some embodiments, the bonding pads
748 include gold (Au) or a gold alloy, and can be bonded to tin
layers on the upper surface of the wall 746 and the internal
interconnect pillar 726. The bonding pad 748b to which the internal
interconnect pillar 726 is bonded may be in electrical
communication, via an interconnect or other suitable structure,
with the IDT electrodes 720b of the second SAW wafer 700b.
[0149] After bonding the second SAW wafer 700b to the first SAW
wafer 700a to form the packaged acoustic wave component 702, the
lower surface of the first SAW wafer 700a may be ground back to
reduce the thickness of the piezoelectric layer 710a to a desired
thickness. In the illustrated embodiment, the piezoelectric layer
710a has been reduced to a smaller thickness than the thickness of
the piezoelectric layer 710b.
[0150] In FIG. 7J, the outer surface of the piezoelectric layer
710a has been exposed to illumination from an etching layer at
least at two locations. The first location is on the opposite side
of the stopper structure 728a (see FIG. 7D) at or near the base of
the interconnect layer 722. A first laser-drilled via 780a has been
formed at this first location, stopping on the stopper structure
underlying the interconnect layer 722 to expose a portion of the
stopper structure underlying interconnect layer 722. The second
location is on the opposite side of the stopper structure 728b (see
FIG. 7D) at or near the base of the internal interconnect pillar
726. A second laser-drilled via 780b has been formed at this
location, stopping on the stopper structure of the internal
interconnect pillar 726. The laser-drilled vias 780a and 780b can
extend into the stopper structures of the interconnect layer 722
and the internal interconnect pillar 726, without extending into
the portions of the interconnect layer 722 and the internal
interconnect pillar 726 overlying the stopper structures.
[0151] In FIG. 7K, after the formation of the laser-drilled vias
780a and 780b, a seed layer 782 has been formed over at least a
portion of the outer surface of the piezoelectric layer 710a and
coating the interior surfaces of the laser-drilled vias 780a and
780b and the exposed sections of the stopper structures. This seed
layer 782 may be formed by sputter deposition or another suitable
process.
[0152] In FIG. 7L, a photoresist layer 784 has been formed over the
seed layer 782, and patterned to form apertures exposing portions
of the seed layer 782 covering the interior of the vias 780a and
780b and immediately adjacent the vias 780a and 780b. The size of
the apertures in the photoresist layer 784 will define the size of
the interconnect structures which will be formed within the
photoresist layer 784. By exposing portions of the seed layer 782
adjacent the vias 780a and 780b, the interconnect structures may be
made larger than the vias 780a and 780b themselves.
[0153] In FIG. 7M, interconnect structures 786a and 786b have been
formed over the exposed portion of the seed layer 782, within the
apertures formed in the photoresist layer 784. The interconnect
structures 786a and 786b cover at least the respective vias 780a
and 780b and the portions of the seed layer immediately surrounding
the vias 780a and 780b. The interconnect structures 786a and 786b
may be formed, for example, by electroplating onto the seed layer,
or using any other suitable fabrication process. In some
embodiments, the lower surfaces of the interconnect structures may
be planarized after the electroplating process. The interconnect
structures 786a and 786b may include copper or other suitable
conductive materials. The interconnect structure 786a and 786b can
include a conductive materials 788a and 788b disposed in the vias
780a and 780b, and the interconnect pillar 726.
[0154] In FIG. 7N, lower layers 789a and 789b have been added to
interconnect structures 786a and 786b. In such embodiments, the
interconnect structures 786a and 786b can include multiple layers
of materials, such as a layer of copper adjacent the seed layer,
followed by lower layers 789a and 789b including tin, formed on the
exposed lower surfaces of the interconnect structures. The
formation of a lower layer 789a and 789b on the exposed lower
surfaces of the interconnect structures 786a and 786b can
facilitate bonding of the finished packages to other
components.
[0155] In FIG. 7O, the photoresist layer 784 and the exposed
portions of the seed layer have been removed, leaving the
interconnect structures 786a and 786b. A packaged acoustic wave
component 700 has been formed, including IDT electrodes 720a and
720b on facing piezoelectric layers 710a and 710b. The interconnect
structure 786a extends into the via 780a, and is in electrical
communication with the IDT electrodes 720a through the interconnect
layer 722 on the opposite side of the piezoelectric layer 710a,
allowing communication with the IDT electrodes 720a through the
piezoelectric layer 710a. The interconnect structure 786b extends
into the via 780b, and is in electrical communication with the IDT
electrodes 720b through the internal interconnect pillar 726 on the
opposite side of the piezoelectric layer 710a, allowing
communication with the IDT electrodes 720b through the same
piezoelectric layer 710a, rather than through the piezoelectric
layer 710b supporting the IDT electrodes 720b.
[0156] FIG. 8 is a schematic diagram of an example transmit filter
800 that includes surface acoustic wave resonators of a surface
acoustic wave component according to an embodiment. The transmit
filter 800 can be a band pass filter. The illustrated transmit
filter 800 is arranged to filter a radio frequency signal received
at a transmit port TX and provide a filtered output signal to an
antenna port ANT. Some or all of the SAW resonators TS1 to TS7
and/or TP1 to TP5 can be SAW resonators in communication with a
conductive structure extending through a laser-drilled via in
accordance with any suitable principles and advantages disclosed
herein. In addition, two or more of the SAW resonators of the
transmit filter 800 can be in a stacked resonator package such as
the packaged acoustic wave component 700 of FIG. 7J. Alternatively
or additionally, one or more of the SAW resonators of the transmit
filter 800 can be any surface acoustic wave resonator disclosed
herein, or part of a stacked resonator package disclosed herein.
Any suitable number of series SAW resonators and shunt SAW
resonators can be included in a transmit filter 800.
[0157] FIG. 9 is a schematic diagram of a receive filter 900 that
includes surface acoustic wave resonators of a surface acoustic
wave component according to an embodiment. The receive filter 900
can be a band pass filter. The illustrated receive filter 900 is
arranged to filter a radio frequency signal received at an antenna
port ANT and provide a filtered output signal to a receive port RX.
Some or all of the SAW resonators RS1 to RS8 and/or RP1 to RP6 can
be SAW resonators in communication with a conductive structure
extending through a laser-drilled via in accordance with any
suitable principles and advantages disclosed herein. In addition,
two or more of the SAW resonators of the receive filter 900 can be
in a stacked resonator package such as the packaged acoustic wave
component 700 of FIG. 7J. Alternatively or additionally, one or
more of the SAW resonators of the receive filter 900 can be any
surface acoustic wave resonator disclosed herein, or part of a
stacked resonator package disclosed herein. Any suitable number of
series SAW resonators and shunt SAW resonators can be included in a
receive filter 950.
[0158] FIG. 10 is a schematic diagram of a radio frequency module
1000 that includes a surface acoustic wave component 1076 according
to an embodiment. The illustrated radio frequency module 1000
includes the SAW component 1076 and other circuitry 1077. The SAW
component 1076 can include one or more SAW resonators with any
suitable combination of features of the SAW resonators disclosed
herein. The SAW component 1076 can include a SAW die that includes
SAW resonators.
[0159] The SAW component 1076 shown in FIG. 10 includes a filter
1078 and terminals 1079A and 1079B. The filter 1078 includes SAW
resonators. One or more of the SAW resonators can be SAW resonators
in communication with a conductive structure extending through a
laser-drilled via in accordance with any suitable principles and
advantages disclosed herein. In addition, two or more of the SAW
resonators of the filter 1078 can be in a stacked resonator package
such as the packaged acoustic wave component 700 of FIG. 7J. The
terminals 1079A and 1078B can serve, for example, as an input
contact and an output contact, and may be in electrical
communication with a conductive structure extending through a
laser-drilled via. The SAW component 1076 and the other circuitry
1077 are on or positioned over a common packaging substrate 1080 in
FIG. 10. The package substrate 1080 can be a laminate substrate.
The terminals 1079A and 1079B can be electrically connected to
contacts 1081A and 1081B, respectively, on or positioned over the
packaging substrate 1080 by way of electrical connectors 1082A and
1082B, respectively. The electrical connectors 1082A and 1082B can
be bumps or wire bonds, for example. The other circuitry 1077 can
include any suitable additional circuitry. For example, the other
circuitry can include one or more one or more power amplifiers, one
or more radio frequency switches, one or more additional filters,
one or more low noise amplifiers, the like, or any suitable
combination thereof. The radio frequency module 1000 can include
one or more packaging structures to, for example, provide
protection and/or facilitate easier handling of the radio frequency
module 1000. Such a packaging structure can include an overmold
structure formed over the packaging substrate 1080. The overmold
structure can encapsulate some or all of the components of the
radio frequency module 1000.
[0160] FIG. 11 is a schematic diagram of a radio frequency module
1100 that includes a surface acoustic wave component according to
an embodiment. As illustrated, the radio frequency module 1100
includes duplexers 1185A to 1185N that include respective transmit
filters 1186A1 to 1186N1 and respective receive filters 1186A2 to
1186N2, a power amplifier 1187, a select switch 1188, and an
antenna switch 1189. The radio frequency module 1100 can include a
package that encloses the illustrated elements. The illustrated
elements can be disposed on a common packaging substrate 1180. The
packaging substrate can be a laminate substrate, for example.
[0161] The duplexers 1185A to 1185N can each include two acoustic
wave filters coupled to a common node. The two acoustic wave
filters can be a transmit filter and a receive filter. As
illustrated, the transmit filter and the receive filter can each be
band pass filters arranged to filter a radio frequency signal. One
or more of the transmit filters 1186A1 to 1186N1 can include one or
more SAW resonators in accordance with any suitable principles and
advantages disclosed herein. Similarly, one or more of the receive
filters 1186A2 to 1186N2 can include one or more SAW resonators in
accordance with any suitable principles and advantages disclosed
herein. Although FIG. 12 illustrates duplexers, any suitable
principles and advantages disclosed herein can be implemented in
other multiplexers (e.g., quadplexers, hexaplexers, octoplexers,
etc.) and/or in switch-plexers.
[0162] The power amplifier 1187 can amplify a radio frequency
signal. The illustrated switch 1188 is a multi-throw radio
frequency switch. The switch 1188 can electrically couple an output
of the power amplifier 1187 to a selected transmit filter of the
transmit filters 1186A1 to 1186N1. In some instances, the switch
1188 can electrically connect the output of the power amplifier
1187 to more than one of the transmit filters 1186A1 to 1186N1. The
antenna switch 1189 can selectively couple a signal from one or
more of the duplexers 1185A to 1185N to an antenna port ANT. The
duplexers 1185A to 1185N can be associated with different frequency
bands and/or different modes of operation (e.g., different power
modes, different signaling modes, etc.).
[0163] FIG. 12 is a schematic block diagram of a module 1210 that
includes a power amplifier 1292, a radio frequency switch 1293, and
duplexers 1291A to 1291N in accordance with one or more
embodiments. The power amplifier 1292 can amplify a radio frequency
signal. The radio frequency switch 1293 can be a multi-throw radio
frequency switch. The radio frequency switch 1293 can electrically
couple an output of the power amplifier 1292 to a selected transmit
filter of the duplexers 1291A to 1291N. One or more filters of the
duplexers 1291A to 1291N can include any suitable number of surface
acoustic wave resonators in communication with a conductive
structure extending through a laser-drilled via, or as part of a
stacked resonator package, in accordance with any suitable
principles and advantages discussed herein. Any suitable number of
duplexers 1291A to 1291N can be implemented.
[0164] FIG. 13 is a schematic block diagram of a module 1395 that
includes duplexers 1391A to 1391N and an antenna switch 1394. One
or more filters of the duplexers 1391A to 1391N can include any
suitable number of surface acoustic wave resonators in
communication with a conductive structure extending through a
laser-drilled via, or as part of a stacked resonator package, in
accordance with any suitable principles and advantages discussed
herein. Any suitable number of duplexers 1391A to 1391N can be
implemented. The antenna switch 1394 can have a number of throws
corresponding to the number of duplexers 1391A to 1391N. The
antenna switch 1394 can electrically couple a selected duplexer to
an antenna port of the module 1395.
[0165] FIG. 14 is a schematic diagram of a wireless communication
device 1400 that includes filters 1403 in a radio frequency front
end 1402 according to an embodiment. The filters 1403 can include
one or more SAW resonators in accordance with any suitable
principles and advantages discussed herein. The wireless
communication device 1400 can be any suitable wireless
communication device. For instance, a wireless communication device
1400 can be a mobile phone, such as a smart phone. As illustrated,
the wireless communication device 1400 includes an antenna 1401, an
RF front end 1402, a transceiver 1404, a processor 1405, a memory
1406, and a user interface 1407. The antenna 1401 can transmit RF
signals provided by the RF front end 1402. Such RF signals can
include carrier aggregation signals. Although not illustrated, the
wireless communication device 1400 can include a microphone and a
speaker in certain applications.
[0166] The RF front end 1402 can include one or more power
amplifiers, one or more low noise amplifiers, one or more RF
switches, one or more receive filters, one or more transmit
filters, one or more duplex filters, one or more multiplexers, one
or more frequency multiplexing circuits, the like, or any suitable
combination thereof. The RF front end 1402 can transmit and receive
RF signals associated with any suitable communication standards.
The filters 1403 can include SAW resonators of a SAW component that
includes any suitable combination of features discussed with
reference to any embodiments discussed above.
[0167] The transceiver 1404 can provide RF signals to the RF front
end 1402 for amplification and/or other processing. The transceiver
1404 can also process an RF signal provided by a low noise
amplifier of the RF front end 1402. The transceiver 1404 is in
communication with the processor 1405. The processor 1405 can be a
baseband processor. The processor 1405 can provide any suitable
base band processing functions for the wireless communication
device 1400. The memory 1406 can be accessed by the processor 1405.
The memory 1406 can store any suitable data for the wireless
communication device 1400. The user interface 1407 can be any
suitable user interface, such as a display with touch screen
capabilities.
[0168] FIG. 15 is a schematic diagram of a wireless communication
device 1510 that includes filters 1503 in a radio frequency front
end 1502 and second filters 1513 in a diversity receive module
1512. The wireless communication device 1510 is like the wireless
communication device 1500 of FIG. 14, except that the wireless
communication device 1520 also includes diversity receive features.
As illustrated in FIG. 15, the wireless communication device 1520
includes a diversity antenna 1511, a diversity module 1512
configured to process signals received by the diversity antenna
1511 and including filters 1513, and a transceiver 1504 in
communication with both the radio frequency front end 1502 and the
diversity receive module 1512. The filters 1513 can include one or
more SAW resonators that include any suitable combination of
features discussed with reference to any embodiments discussed
above.
[0169] Although embodiments disclosed herein relate to surface
acoustic wave resonators, any suitable principles and advantages
disclosed herein can be applied to other types of acoustic wave
resonators, such as Lamb wave resonators and/or boundary wave
resonators. For example, any resonator including a substrate
suitable for etching by lasers can have a laser-drilled via formed
therethrough, using a stopper layer or stopper structure which is
highly reflective to the wavelength of the etching laser. These
vias can be used to provide communication with the resonator into a
package enclosing the resonator, where the substrate through which
the via is laser-drilled is used to form part of the package
enclosing the resonator.
[0170] Any of the embodiments described above can be implemented in
association with mobile devices such as cellular handsets. The
principles and advantages of the embodiments can be used for any
systems or apparatus, such as any uplink wireless communication
device, that could benefit from any of the embodiments described
herein. The teachings herein are applicable to a variety of
systems. Although this disclosure includes some example
embodiments, the teachings described herein can be applied to a
variety of structures. Any of the principles and advantages
discussed herein can be implemented in association with RF circuits
configured to process signals in a frequency range from about 30
kHz to 300 GHz, such as in a frequency range from about 450 MHz to
8.5 GHz.
[0171] An acoustic wave resonator including any suitable
combination of features disclosed herein can be included in a
filter arranged to filter a radio frequency signal in a fifth
generation (5G) New Radio (NR) operating band within Frequency
Range 1 (FR1). A filter arranged to filter a radio frequency signal
in a 5G NR operating band can include one or more acoustic wave
resonators disclosed herein. FR1 can be from 410 MHz to 7.125 GHz,
for example, as specified in a current 5G NR specification. One or
more acoustic wave resonators in accordance with any suitable
principles and advantages disclosed herein can be included in a
filter arranged to filter a radio frequency signal in a fourth
generation (4G) Long Term Evolution (LTE) operating band and/or in
a filter with a passband that spans a 4G LTE operating band and a
5G NR operating band.
[0172] Aspects of this disclosure can be implemented in various
electronic devices. Examples of the electronic devices can include,
but are not limited to, consumer electronic products, parts of the
consumer electronic products such as die and/or acoustic wave
components and/or acoustic wave filter assemblies and/or packaged
radio frequency modules, uplink wireless communication devices,
wireless communication infrastructure, electronic test equipment,
etc. Examples of the electronic devices can include, but are not
limited to, a mobile phone such as a smart phone, a wearable
computing device such as a smart watch or an ear piece, a
telephone, a television, a computer monitor, a computer, a modem, a
hand-held computer, a laptop computer, a tablet computer, a
personal digital assistant (PDA), a microwave, a refrigerator, an
automobile, a stereo system, a DVD player, a CD player, a digital
music player such as an MP3 player, a radio, a camcorder, a camera,
a digital camera, a portable memory chip, a washer, a dryer, a
washer/dryer, a copier, a facsimile machine, a scanner, a
multi-functional peripheral device, a wrist watch, a clock, etc.
Further, the electronic devices can include unfinished
products.
[0173] Unless the context clearly requires otherwise, throughout
the description and the claims, the words "comprise," "comprising,"
"include," "including" and the like are to be construed in an
inclusive sense, as opposed to an exclusive or exhaustive sense;
that is to say, in the sense of "including, but not limited to."
The word "coupled", as generally used herein, refers to two or more
elements that may be either directly connected, or connected by way
of one or more intermediate elements. Likewise, the word
"connected", as generally used herein, refers to two or more
elements that may be either directly connected, or connected by way
of one or more intermediate elements. Additionally, the words
"herein," "above," "below," and words of similar import, when used
in this application, shall refer to this application as a whole and
not to any particular portions of this application. Where the
context permits, words in the above Detailed Description using the
singular or plural number may also include the plural or singular
number respectively. The word "or" in reference to a list of two or
more items, that word covers all of the following interpretations
of the word: any of the items in the list, all of the items in the
list, and any combination of the items in the list.
[0174] Moreover, conditional language used herein, such as, among
others, "can," "could," "might," "may," "e.g.," "for example,"
"such as" and the like, unless specifically stated otherwise, or
otherwise understood within the context as used, is generally
intended to convey that certain embodiments include, while other
embodiments do not include, certain features, elements and/or
states. Thus, such conditional language is not generally intended
to imply that features, elements and/or states are in any way
required for one or more embodiments.
[0175] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the disclosure. Indeed, the novel
apparatus, methods, and systems described herein may be embodied in
a variety of other forms; furthermore, various omissions,
substitutions and changes in the form of the methods and systems
described herein may be made without departing from the spirit of
the disclosure. For example, while blocks are presented in a given
arrangement, alternative embodiments may perform similar
functionalities with different components and/or circuit
topologies, and some blocks may be deleted, moved, added,
subdivided, combined, and/or modified. Each of these blocks may be
implemented in a variety of different ways. Any suitable
combination of the elements and acts of the various embodiments
described above can be combined to provide further embodiments. The
accompanying claims and their equivalents are intended to cover
such forms or modifications as would fall within the scope and
spirit of the disclosure.
* * * * *