U.S. patent application number 17/176977 was filed with the patent office on 2022-08-18 for optical component alignment system and method using plural fiducials.
This patent application is currently assigned to MACOM Technology Solutions Holdings, Inc.. The applicant listed for this patent is MACOM Technology Solutions Holdings, Inc.. Invention is credited to Thomas Robert Daugherty, Michael Everett Fangman, Hendrikus Johannes Jacobus Thoonen.
Application Number | 20220260793 17/176977 |
Document ID | / |
Family ID | 1000006504970 |
Filed Date | 2022-08-18 |
United States Patent
Application |
20220260793 |
Kind Code |
A1 |
Fangman; Michael Everett ;
et al. |
August 18, 2022 |
OPTICAL COMPONENT ALIGNMENT SYSTEM AND METHOD USING PLURAL
FIDUCIALS
Abstract
Systems and methods are provided to align a first optical
component carried by a first semiconductor chip with a second
optical component carried by a second semiconductor chip. Each of
the first semiconductor chip and the second semiconductor chip may
include at least one primary semiconductor chip fiducial which
assists in the alignment of the first optical component carried by
a first semiconductor chip with a second optical component carried
by a second semiconductor chip.
Inventors: |
Fangman; Michael Everett;
(Reading, PA) ; Daugherty; Thomas Robert;
(Allentown, PA) ; Thoonen; Hendrikus Johannes
Jacobus; (Nijmegen, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MACOM Technology Solutions Holdings, Inc. |
Lowell |
MA |
US |
|
|
Assignee: |
MACOM Technology Solutions
Holdings, Inc.
Lowell
MA
|
Family ID: |
1000006504970 |
Appl. No.: |
17/176977 |
Filed: |
February 16, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 6/4224 20130101;
G02B 6/4236 20130101; G02B 6/1225 20130101 |
International
Class: |
G02B 6/42 20060101
G02B006/42; G02B 6/122 20060101 G02B006/122 |
Claims
1. A method of aligning a first optical component and a second
optical component, the method comprising the steps of: detecting a
first primary fiducial associated with the first optical component;
detecting a second primary fiducial associated with the second
optical component; determining a first secondary fiducial
associated with the first optical component based on the detected
first primary fiducial associated with the first optical component;
determining a second secondary fiducial associated with the second
optical component based on the detected second primary fiducial
associated with the second optical component; determining the first
secondary fiducial associated with the first optical component and
the second secondary fiducial associated with the second optical
component indicate the first optical component and the second
optical component are misaligned; and moving at least one of the
first optical component and the second optical component relative
to the other of the first optical component and the second optical
component to align the first optical component and the second
optical component based on the first secondary fiducial associated
with the first optical component and the second secondary fiducial
associated with the second optical component.
2. The method of claim 1, wherein the first optical component is
carried by a first semiconductor chip and the second optical
component is carried by a second semiconductor chip.
3. The method of claim 2, wherein the first semiconductor chip
includes a first face facing the second semiconductor chip and a
second face opposite the first face and the second semiconductor
chip includes a first face facing the first semiconductor chip and
a second face opposite the first face, each of the first primary
fiducial associated with the first optical component and the second
primary fiducial associated with the second optical component being
positioned between the second face of the first semiconductor chip
and the second face of the second semiconductor chip.
4. The method of claim 3, further comprising the steps of:
illuminating the first semiconductor chip and the second
semiconductor chip with a light source at a first wavelength, the
first wavelength being an infrared wavelength; and detecting light
passing through the first semiconductor chip and the second
semiconductor chip, wherein the steps of detecting the first
primary fiducial associated with the first optical component and
detecting the second primary fiducial associated with the second
optical component are based on the light passing through the first
semiconductor chip and the second semiconductor chip.
5. The method of claim 4, further comprising the step of nesting
the first primary fiducial associated with the first optical
component in the second primary fiducial associated with the second
optical component.
6. The method of claim 4, wherein the step of determining the first
secondary fiducial associated with the first optical component
based on the detected first primary fiducial associated with the
first optical component includes the steps of: detecting feature
information associated with the first primary fiducial associated
with the first optical component; and determining the first
secondary fiducial associated with the first optical component
based on the detected feature information; and the step of
determining the second secondary fiducial associated with the
second optical component based on the detected second primary
fiducial associated with the second optical component includes the
steps of: detecting feature information associated with the second
primary fiducial associated with the second optical component; and
determining the second secondary fiducial associated with the
second optical component based on the detected feature
information.
7. The method of claim 6, wherein the detected feature information
associated with the first primary fiducial associated with the
first optical component includes a first plurality of points and
the step of determining the first secondary fiducial associated
with the first optical component based on the detected first
primary fiducial associated with the first optical component
includes the step of: fitting a circle to the first plurality of
points to determine a first center of curvature, the first
secondary fiducial associated with the first optical component
being the first center of curvature; and the detected feature
information associated with the second primary fiducial associated
with the second optical component includes a second plurality of
points and the step of determining the second secondary fiducial
associated with the second optical component based on the detected
second primary fiducial associated with the second optical
component includes the step of: fitting a circle to the second
plurality of points to determine a second center of curvature, the
second secondary fiducial associated with the second optical
component being the second center of curvature.
8. The method of claim 7, wherein the first optical component and
the second optical component are aligned when the first secondary
fiducial and the second secondary fiducial are in a first
arrangement.
9. The method of claim 8, wherein the first arrangement is
vertically aligned.
10. The method of claim 8, wherein the first arrangement is a known
offset.
11. The method of claim 1, wherein the first optical component and
the second optical component are aligned when the first secondary
fiducial and the second secondary fiducial are in a first
arrangement.
12. The method of claim 11, wherein the first arrangement is
vertically aligned.
13. The method of claim 11, wherein the first arrangement is a
known offset.
14. The method of claim 1, further comprising the step of nesting
the first primary fiducial associated with the first optical
component in the second primary fiducial associated with the second
optical component.
15. An optical assembly comprising: a first optical component
carried by a first semiconductor chip; a second optical component
carried by a second semiconductor chip, the first semiconductor
chip coupled to the second semiconductor chip and positioned
relative to the second semiconductor chip to align the first
optical component with the second optical component, the first
semiconductor chip having a first face facing the second
semiconductor chip and a second face opposite the first face and
the second semiconductor chip having a first face facing the first
semiconductor chip and a second face opposite the first face; a
first primary semiconductor chip fiducial carried by the first
semiconductor chip and positioned between the second face of the
first semiconductor chip and the second face of the second
semiconductor chip; a second primary semiconductor chip fiducial
carried by the second semiconductor chip and positioned between the
second face of the first semiconductor chip and the second face of
the second semiconductor chip; wherein when the first optical
component is aligned with the second optical component the first
primary semiconductor chip fiducial has a first position relative
to the second primary semiconductor chip fiducial and the first
primary semiconductor chip is spaced apart from the second primary
semiconductor chip fiducial in at least two orthogonal degrees of
freedom.
16. The optical assembly of claim 15, wherein one of the first
primary semiconductor chip fiducial and the second primary
semiconductor chip fiducial nests within the other of the first
primary semiconductor chip fiducial and the second primary
semiconductor chip fiducial.
17. The optical assembly of claim 15, wherein the first optical
component is formed at a first layer of the first semiconductor
chip and the first primary semiconductor chip fiducial is formed at
the first layer.
18. The optical assembly of claim 15, wherein the second optical
component is formed at a first layer of the second semiconductor
chip and the second primary semiconductor chip fiducial is formed
at the first layer.
19. The optical system of claim 15, wherein the first primary
semiconductor chip fiducial includes a first curved portion having
a first radius curvature and the second primary semiconductor chip
fiducial includes a first curved portion having a second radius
curvature, the second radius of curvature being different than the
first radius of curvature.
20. The optical system of claim 19, wherein a first center of
curvature of the first curved portion and a second center of
curvature of the second curved portion are vertically aligned when
the first optical component carried by the first semiconductor chip
and the second optical component carried by the second
semiconductor chip are aligned.
Description
FIELD
[0001] The present disclosure relates to alignment systems and
methods and in particular to alignment systems and methods for
aligning optical components.
BACKGROUND
[0002] In some conventional optical systems, a semiconductor laser
of a first semiconductor chip must be aligned with an optical
component in a second semiconductor chip. Generally, the first
semiconductor chip is stacked on top of the second semiconductor
chip, or vice versa, and the semiconductor laser is coupled to the
optical component of the second semiconductor chip through the
faces of the first semiconductor chip and the second semiconductor
chip facing each other. Since the first semiconductor chip and the
second semiconductor chip are opaque to visible light, a visible
alignment is not possible. Improvements in systems to permit
alignment of optical components carried by respective semiconductor
chips is needed.
SUMMARY
[0003] In an exemplary embodiment of the present disclosure, a
method of aligning a first optical component and a second optical
component is provided. The method comprising the steps of:
detecting a first primary fiducial associated with the first
optical component; detecting a second primary fiducial associated
with the second optical component; determining a first secondary
fiducial associated with the first optical component based on the
detected first primary fiducial associated with the first optical
component; determining a second secondary fiducial associated with
the second optical component based on the detected second primary
fiducial associated with the second optical component; determining
the first secondary fiducial associated with the first optical
component and the second secondary fiducial associated with the
second optical component indicate the first optical component and
the second optical component are misaligned; and moving at least
one of the first optical component and the second optical component
relative to the other of the first optical component and the second
optical component to align the first optical component and the
second optical component based on the first secondary fiducial
associated with the first optical component and the second
secondary fiducial associated with the second optical
component.
[0004] In an example thereof, the first optical component is
carried by a first semiconductor chip and the second optical
component is carried by a second semiconductor chip. In a variation
thereof, the first semiconductor chip includes a first face facing
the second semiconductor chip and a second face opposite the first
face and the second semiconductor chip includes a first face facing
the first semiconductor chip and a second face opposite the first
face, each of the first primary fiducial associated with the first
optical component and the second primary fiducial associated with
the second optical component being positioned between the second
face of the first semiconductor chip and the second face of the
second semiconductor chip. In a further variation thereof, the
method further comprises the steps of: illuminating the first
semiconductor chip and the second semiconductor chip with a light
source at a first wavelength, the first wavelength being an
infrared wavelength; and detecting light passing through the first
semiconductor chip and the second semiconductor chip, wherein the
steps of detecting the first primary fiducial associated with the
first optical component and detecting the second primary fiducial
associated with the second optical component are based on the light
passing through the first semiconductor chip and the second
semiconductor chip. In a still further variation thereof, the
method further comprises the step of nesting the first primary
fiducial associated with the first optical component in the second
primary fiducial associated with the second optical component. In a
further still variation thereof, the step of determining the first
secondary fiducial associated with the first optical component
based on the detected first primary fiducial associated with the
first optical component includes the steps of: detecting feature
information associated with the first primary fiducial associated
with the first optical component; and determining the first
secondary fiducial associated with the first optical component
based on the detected feature information; and the step of
determining the second secondary fiducial associated with the
second optical component based on the detected second primary
fiducial associated with the second optical component includes the
steps of: detecting feature information associated with the second
primary fiducial associated with the second optical component; and
determining the second secondary fiducial associated with the
second optical component based on the detected feature information.
In yet a further still variation thereof, the detected feature
information associated with the first primary fiducial associated
with the first optical component includes a first plurality of
points and the step of determining the first secondary fiducial
associated with the first optical component based on the detected
first primary fiducial associated with the first optical component
includes the step of: fitting a circle to the first plurality of
points to determine a first center of curvature, the first
secondary fiducial associated with the first optical component
being the first center of curvature; and the detected feature
information associated with the second primary fiducial associated
with the second optical component includes a second plurality of
points and the step of determining the second secondary fiducial
associated with the second optical component based on the detected
second primary fiducial associated with the second optical
component includes the step of: fitting a circle to the second
plurality of points to determine a second center of curvature, the
second secondary fiducial associated with the second optical
component being the second center of curvature. In a further yet
variation thereof, the first optical component and the second
optical component are aligned when the first secondary fiducial and
the second secondary fiducial are in a first arrangement. In
another variation thereof, the first arrangement is vertically
aligned. In still another variation thereof, the first arrangement
is a known offset.
[0005] In another example thereof, the first optical component and
the second optical component are aligned when the first secondary
fiducial and the second secondary fiducial are in a first
arrangement. In a variation thereof, the first arrangement is
vertically aligned. In another variation thereof, the first
arrangement is a known offset.
[0006] In a further example thereof, the method further comprises
the step of nesting the first primary fiducial associated with the
first optical component in the second primary fiducial associated
with the second optical component.
[0007] In another exemplary embodiment of the present disclosure,
an optical assembly is provided. The optical assembly comprising: a
first optical component carried by a first semiconductor chip; a
second optical component carried by a second semiconductor chip,
the first semiconductor chip coupled to the second semiconductor
chip and positioned relative to the second semiconductor chip to
align the first optical component with the second optical
component, the first semiconductor chip having a first face facing
the second semiconductor chip and a second face opposite the first
face and the second semiconductor chip having a first face facing
the first semiconductor chip and a second face opposite the first
face; a first primary semiconductor chip fiducial carried by the
first semiconductor chip and positioned between the second face of
the first semiconductor chip and the second face of the second
semiconductor chip; a second primary semiconductor chip fiducial
carried by the second semiconductor chip and positioned between the
second face of the first semiconductor chip and the second face of
the second semiconductor chip; wherein when the first optical
component is aligned with the second optical component the first
primary semiconductor chip fiducial has a first position relative
to the second primary semiconductor chip fiducial and the first
primary semiconductor chip is spaced apart from the second primary
semiconductor chip fiducial in at least two orthogonal degrees of
freedom.
[0008] In an example thereof, one of the first primary
semiconductor chip fiducial and the second primary semiconductor
chip fiducial nests within the other of the first primary
semiconductor chip fiducial and the second primary semiconductor
chip fiducial.
[0009] In another example thereof, the first optical component is
formed at a first layer of the first semiconductor chip and the
first primary semiconductor chip fiducial is formed at the first
layer.
[0010] In a further example thereof, the second optical component
is formed at a first layer of the second semiconductor chip and the
second primary semiconductor chip fiducial is formed at the first
layer.
[0011] In yet another example thereof, the first primary
semiconductor chip fiducial includes a first curved portion having
a first radius curvature and the second primary semiconductor chip
fiducial includes a first curved portion having a second radius
curvature, the second radius of curvature being different than the
first radius of curvature. In a variation thereof, a first center
of curvature of the first curved portion and a second center of
curvature of the second curved portion are vertically aligned when
the first optical component carried by the first semiconductor chip
and the second optical component carried by the second
semiconductor chip are aligned.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The above-mentioned and other features and advantages of
this disclosure, and the manner of attaining them, will become more
apparent and will be better understood by reference to the
following description of exemplary embodiments taken in conjunction
with the accompanying drawings, wherein:
[0013] FIG. 1 illustrates a representative side view of a first
optical component carried by a first semiconductor chip and a
second optical component carried by a second semiconductor chip
prior to alignment of the first semiconductor chip to the second
semiconductor chip in a vertical direction;
[0014] FIG. 2 illustrates a representative top view of the first
optical component carried by the first semiconductor chip
misaligned relative to the second optical component carried by the
second semiconductor chip in a first horizontal direction and
aligned in a second horizontal direction orthogonal to the first
horizontal direction;
[0015] FIG. 3 illustrates a representative top view of the first
optical component carried by the first semiconductor chip aligned
relative to the second optical component carried by the second
semiconductor chip in the first horizontal direction and misaligned
in the second horizontal direction orthogonal to the first
horizontal direction;
[0016] FIG. 4 illustrates a representative top view of the first
optical component carried by the first semiconductor chip aligned
relative to the second optical component carried by the second
semiconductor chip in the first horizontal direction and aligned in
the second horizontal direction orthogonal to the first horizontal
direction;
[0017] FIG. 5 illustrates a representative top view of the second
optical component and second semiconductor chip, the second
semiconductor chip further carrying a plurality of primary second
semiconductor chip fiducials;
[0018] FIG. 6 illustrates a representative side view of the second
optical component and second semiconductor chip, the second
semiconductor chip further carrying the plurality of primary second
semiconductor chip fiducials;
[0019] FIG. 7 illustrates a representative top view of the first
optical component and first semiconductor chip, the first
semiconductor chip further carrying a plurality of primary first
semiconductor chip fiducials;
[0020] FIG. 8 illustrates a representative side view of the first
optical component and first semiconductor chip, the first
semiconductor chip further carrying the plurality of primary first
semiconductor chip fiducials;
[0021] FIG. 9 illustrates a representative top view of the first
optical component carried by the first semiconductor chip aligned
relative to the second optical component carried by the second
semiconductor chip in the first horizontal direction and aligned in
the second horizontal direction orthogonal to the first horizontal
direction, the plurality of primary first semiconductor chip
fiducials of the first semiconductor chip are aligned with the
plurality of primary second semiconductor chip fiducials of the
second semiconductor chip;
[0022] FIG. 10 illustrates a system diagram of an alignment system
to align the first optical component carried by the first
semiconductor chip relative to the second optical component carried
by the second semiconductor chip in the first horizontal direction
and in the second horizontal direction orthogonal to the first
horizontal direction;
[0023] FIG. 11 illustrates an exemplary processing sequence carried
out by the alignment system of FIG. 10 to align the first optical
component carried by the first semiconductor chip relative to the
second optical component carried by the second semiconductor chip
in the first horizontal direction and in the second horizontal
direction orthogonal to the first horizontal direction;
[0024] FIG. 12 illustrates a first primary first semiconductor chip
fiducial of the first semiconductor chip, a first determined
secondary first semiconductor chip fiducial of the first
semiconductor chip; a first primary second semiconductor chip
fiducial of the second semiconductor chip, and a first determined
secondary second semiconductor chip fiducial of the second
semiconductor chip, wherein the first optical component carried by
the first semiconductor chip is misaligned relative to the second
optical component carried by the second semiconductor chip in both
the first horizontal direction and in the second horizontal
direction orthogonal to the first horizontal direction;
[0025] FIG. 13 illustrates the first primary first semiconductor
chip fiducial of the first semiconductor chip, the first determined
secondary first semiconductor chip fiducial of the first
semiconductor chip; the first primary second semiconductor chip
fiducial of the second semiconductor chip, and the first determined
secondary second semiconductor chip fiducial of the second
semiconductor chip, wherein the first optical component carried by
the first semiconductor chip is aligned relative to the second
optical component carried by the second semiconductor chip in the
first horizontal direction and misaligned in the second horizontal
direction orthogonal to the first horizontal direction;
[0026] FIG. 14 illustrates the first primary first semiconductor
chip fiducial of the first semiconductor chip, the first determined
secondary first semiconductor chip fiducial of the first
semiconductor chip; the first primary second semiconductor chip
fiducial of the second semiconductor chip, and the first determined
secondary second semiconductor chip fiducial of the second
semiconductor chip, wherein the first optical component carried by
the first semiconductor chip is aligned relative to the second
optical component carried by the second semiconductor chip in both
the first horizontal direction and in the second horizontal
direction orthogonal to the first horizontal direction;
[0027] FIG. 15 illustrates a top view of a portion of an exemplary
second semiconductor chip including an optical waveguide and a
plurality of primary fiducials in the same layer of the second
semiconductor chip as the optical waveguide;
[0028] FIG. 16 illustrates a bottom view of a portion of an
exemplary first semiconductor chip including a semiconductor laser
and a plurality of primary fiducials in the facet etch layer of the
first semiconductor chip as the optical waveguide; and
[0029] FIG. 17 illustrates a side view of portions of the exemplary
first semiconductor chip of FIG. 16 and the exemplary second
semiconductor chip of FIG. 15.
[0030] Corresponding reference characters indicate corresponding
parts throughout the several views. The exemplification set out
herein illustrates an exemplary embodiment of the invention and
such exemplification is not to be construed as limiting the scope
of the invention in any manner.
DETAILED DESCRIPTION OF THE DRAWINGS
[0031] For the purposes of promoting an understanding of the
principles of the present disclosure, reference is now made to the
embodiments illustrated in the drawings, which are described below.
The embodiments disclosed herein are not intended to be exhaustive
or limit the present disclosure to the precise form disclosed in
the following detailed description. Rather, the embodiments are
chosen and described so that others skilled in the art may utilize
their teachings. Therefore, no limitation of the scope of the
present disclosure is thereby intended. Corresponding reference
characters indicate corresponding parts throughout the several
views.
[0032] The terms "couples", "coupled", "coupler" and variations
thereof are used to include both arrangements wherein the two or
more components are in direct physical contact and arrangements
wherein the two or more components are not in direct contact with
each other (e.g., the components are "coupled" via at least a third
component), but yet still cooperate or interact with each
other.
[0033] In some instances throughout this disclosure and in the
claims, numeric terminology, such as first, second, third, and
fourth, is used in reference to various components or features.
Such use is not intended to denote an ordering of the components or
features. Rather, numeric terminology is used to assist the reader
in identifying the component or features being referenced and
should not be narrowly interpreted as providing a specific order of
components or features.
[0034] Referring to FIG. 1, a first semiconductor chip 10 and a
second semiconductor chip 20 are represented. First semiconductor
chip 10 carries at least a first optical component 12. Second
semiconductor chip 20 carries at least a second optical component
22. Exemplary optical components include semiconductor lasers,
semiconductor waveguides, semiconductor modulators, semiconductor
demodulators, semiconductor couplers, semiconductor decouplers, and
other suitable devices for producing and/or transporting light,
such as light at infrared wavelengths. Techniques to form various
optical components on a semiconductor substrate to form a
semiconductor chip carrying an optical component, such as through
the deposition, etching, and other processes, are known in the
art.
[0035] During manufacturing, it is desired to couple semiconductor
chip 10 to semiconductor chip 20 and position semiconductor chip 10
relative to semiconductor chip 20 to optically align optical
component 12 and optical component 22. The alignment of optical
component 12 to optical component 22 must occur in a vertical,
z-direction 30 (see FIG. 1), a first horizontal, x-direction 32
(see FIG. 2), and a second horizontal, y-direction 34 (see FIG. 2).
As discussed herein, the alignment of semiconductor chip 10 to
semiconductor chip 20 may be carried out by an alignment system 100
(see FIG. 10). As shown in FIG. 1, semiconductor chip 10 is spaced
apart from semiconductor chip 20 in z-direction 30. Alignment
system 100 can lower semiconductor chip 10 relative to
semiconductor chip 20 or raise semiconductor chip 20 relative to
semiconductor chip 10 to one of bring semiconductor chip 10 and
semiconductor chip 20 into contact with each other or into contact
with one or more bonding members, such as adhesives or solder, to
secure semiconductor chip 10 to semiconductor chip 20.
[0036] Referring to FIG. 2, a top view is shown of a horizontal
envelope 14 of semiconductor chip 10, a horizontal envelope 16 of
optical component 12, a horizontal envelope 24 of semiconductor
chip 20, and a horizontal envelope 26 of optical component 22. In
the example of FIG. 2, optical component 12 is aligned to optical
component 22 when a first edge 18 of horizontal envelope 16 of
optical component 12 and a first edge 28 of horizontal envelope 26
of optical component 22 are each aligned with a vertically
extending plane 38 parallel to y-direction 34 and when each of
horizontal envelope 16 of optical component 12 and horizontal
envelope 26 of optical component 22 are centered about a vertically
extending plane 36 parallel to x-direction 32. It should be
understood that this alignment example is only an example and other
alignment criteria may be used in the alignment of optical
component 12 to optical component 22. As shown in FIG. 2, an
arrangement is presented wherein optical component 12 is aligned to
optical component 22 in y-direction 34, but is misaligned relative
to optical component 22 in x-direction 32.
[0037] Referring to FIG. 3, an arrangement is presented wherein
optical component 12 is aligned to optical component 22 in
x-direction 32, but is misaligned relative to optical component 22
in y-direction 34. Referring to FIG. 4, an arrangement is presented
wherein optical component 12 is aligned to optical component 22 in
both x-direction 32 and y-direction 34. Referring back to FIG. 1,
the coupling of optical component 12 to optical component 22 occurs
between a face 19 of semiconductor chip 10 facing semiconductor
chip 20 and a face 29 of semiconductor chip 20 facing semiconductor
chip 10. In embodiments, wherein semiconductor chip 10 is stacked
on top of semiconductor chip 20, face 19 is a lower face of
semiconductor chip 10 and face 29 of semiconductor chip 20 is an
upper face of semiconductor chip 20. In embodiments, wherein
semiconductor chip 20 is stacked on top of semiconductor chip 10,
face 19 is an upper face of semiconductor chip 10 and face 29 of
semiconductor chip 20 is a lower face of semiconductor chip 20. Due
to the opaque nature of semiconductor chip 10 and semiconductor
chip 20 to visible light, a visual alignment of optical component
12 to optical component 22 is not possible with a visible imaging
system.
[0038] Referring to FIG. 10, alignment system 100 is shown.
Alignment system 100 includes a positioning system 102 which is
capable of moving at least one of semiconductor chip 10 and
semiconductor chip 20 relative to the other semiconductor chip 10
and semiconductor chip 20 in each of z-direction 30, x-direction
32, and y-direction 34. positioning system 102 may include various
conventional components such as linear actuators, rotary actuators,
fixtures, sleds, motors, steppers motors, and other suitable
components which hold each of semiconductor chip 10 and
semiconductor chip 20 and provide the relative movement of
semiconductor chip 10 and semiconductor chip 20 relative to each
other.
[0039] Alignment system 100 further includes at least one light
source 104 which illuminates portions of semiconductor chip 10 and
semiconductor chip 20. As noted herein, semiconductor chip 10 and
semiconductor chip 20 are opaque to visible light. In embodiments,
light source 104 provides light in the infrared wavelength range.
In embodiments, light source 104 may be controlled to provide light
at multiple wavelengths. In examples, light source 104 may provide
light of a first wavelength in a first setting and light of a
second wavelength in a second setting, the second wavelength being
different than the first wavelength. Interior features of
semiconductor chip 10 and semiconductor chip 20 and surface
features on the faces of semiconductor chip 10 and semiconductor
chip 20 facing the other of semiconductor chip 10 and semiconductor
chip 20 are visible at the first wavelength and the second
wavelength to an infrared imaging system.
[0040] Alignment system 100 further includes as an imaging system
at least one camera 106 which receives the light from light source
104 which passes through semiconductor chip 10 and semiconductor
chip 20. Exemplary cameras include CCD array cameras and other
suitable cameras. Each of positioning system 102, light source 104,
and camera 106 are operatively coupled to an electronic controller
120.
[0041] Electronic controller 120, in the illustrated embodiment, is
microprocessor-based, includes processor 122, and includes a
non-transitory computer readable medium 124 which includes
processing instructions stored therein that are executable by the
microprocessor 122 of electronic controller 120 to control
operation of positioning system 102, light source 104, and camera
106. A non-transitory computer-readable medium, or memory, may
include random access memory (RAM), read-only memory (ROM),
erasable programmable read-only memory (e.g., EPROM, EEPROM, or
Flash memory), or any other tangible medium capable of storing
information.
[0042] For example, electronic controller 120 may execute an
alignment logic 200 which based on input from camera 106 provides
control signals to positioning system 102 and light source 104 to
align optical component 12 of semiconductor chip 10 to optical
component 22 of semiconductor chip 20. An exemplary processing
sequence 250 of alignment logic 200 is discussed herein in
connection with FIG. 11. The term "logic" as used herein includes
software and/or firmware executing on one or more programmable
processors, application-specific integrated circuits,
field-programmable gate arrays, digital signal processors,
hardwired logic, or combinations thereof. Therefore, in accordance
with the embodiments, various logic may be implemented in any
appropriate fashion and would remain in accordance with the
embodiments herein disclosed. A non-transitory machine-readable
medium comprising logic can additionally be considered to be
embodied within any tangible form of a computer-readable carrier,
such as solid-state memory, magnetic disk, and optical disk
containing an appropriate set of computer instructions and data
structures that would cause a processor to carry out the techniques
described herein. This disclosure contemplates other embodiments in
which electronic controller 120 is not microprocessor-based, but
rather is configured to control operation of positioning system
102, light source 104, and camera 106 based on one or more sets of
hardwired instructions and/or software instructions stored in a
memory unit. Further, electronic controller 120 may be contained
within a single device or be a plurality of devices networked
together to provide the functionality described herein.
[0043] In embodiments, alignment system 100 determines a location
of semiconductor chip 10 relative to semiconductor chip 20 based on
at least one primary semiconductor chip fiducial 50 carried by
semiconductor chip 10 and at least one primary semiconductor chip
fiducial 70 carried by semiconductor chip 20. In embodiments, at
least one primary semiconductor chip fiducial 50 of semiconductor
chip 10 is positioned below an upper face 17 of semiconductor chip
10 which is exposed to light source 104. In one embodiment, at
least one primary semiconductor chip fiducial 50 of semiconductor
chip 10 is positioned at lower face 19 of semiconductor chip 10. In
one embodiment, at least one primary semiconductor chip fiducial 50
of semiconductor chip 10 is positioned between upper face 17 and
lower face 19 of semiconductor chip 10, such as in the illustrated
embodiment of FIG. 10. In embodiments, at least one primary
semiconductor chip fiducial 50 is provided in the same layer of
semiconductor chip 10 as optical component 12. Similarly, in
embodiments, at least one primary semiconductor chip fiducial 70 of
semiconductor chip 20 is positioned below upper face 29 of
semiconductor chip 10. In one embodiment, at least one primary
semiconductor chip fiducial 70 of semiconductor chip 20 is
positioned at upper face 29 of semiconductor chip 20. In one
embodiment, at least one primary semiconductor chip fiducial 70 of
semiconductor chip 20 is positioned between upper face 29 and lower
face 27 of semiconductor chip 20, such as in the illustrated
embodiment of FIG. 10. In embodiments, at least one primary
semiconductor chip fiducial 70 is provided in the same layer of
semiconductor chip 20 as optical component 22.
[0044] In embodiments, at least one primary semiconductor chip
fiducial 50 of semiconductor chip 10 and at least one primary
semiconductor chip fiducial 70 of semiconductor chip 20 nest or are
otherwise overlapping at a given vertical height. In embodiments
wherein at least one primary semiconductor chip fiducial 50 of
semiconductor chip 10 and at least one primary semiconductor chip
fiducial 70 of semiconductor chip 20 nest, there is sufficient gap
between the features of at least one primary semiconductor chip
fiducial 50 and at least one primary semiconductor chip fiducial 70
to permit movement of one of semiconductor chip 10 and
semiconductor chip 20 relative to the other of semiconductor chip
10 and semiconductor chip 20 in x-direction 32 and y-direction 34
to permit alignment system 100 move one of semiconductor chip 10
and semiconductor chip 20 to align optical component 12 to optical
component 22.
[0045] Referring to FIGS. 5 and 6, an exemplary embodiment of
semiconductor chip 20 is illustrated. As shown in FIG. 5, at least
one primary semiconductor chip fiducial 70 includes multiple
fiducials, illustratively primary semiconductor chip fiducial 72A
and primary semiconductor chip fiducial 72B. Each of primary
semiconductor chip fiducial 72A and primary semiconductor chip
fiducial 72B are shown as having an unbroken circular diameter 74A,
74B respectively. In other embodiments, the unbroken circular
diameter 74A, 74B of each of 72A and 72B may be approximated by
non-intersecting curves having the same center of curvature and
either the same or differing diameters. Other exemplary primary
fiducials may be used.
[0046] Further, as shown, primary semiconductor chip fiducials 70
are positioned between upper face 29 and lower face 27 of
semiconductor chip 20. In embodiments, each of primary
semiconductor chip fiducial 72A and primary semiconductor chip
fiducial 72B are at the same height in z-direction 30. In
embodiments, primary semiconductor chip fiducial 72A and primary
semiconductor chip fiducial 72B are at differing heights in
z-direction 30. In embodiments, primary semiconductor chip fiducial
72A and primary semiconductor chip fiducial 72B are vertically
aligned with optical component 22 and formed in the same layer of
semiconductor chip 20 as optical component 22. In embodiments, one
or both of primary semiconductor chip fiducial 72A and primary
semiconductor chip fiducial 72B forms part of upper face 29 of
semiconductor chip 20 or lower face 27 of semiconductor chip
20.
[0047] Referring to FIGS. 7 and 8, an exemplary embodiment of
semiconductor chip 10 is illustrated. As shown in FIG. 7, at least
one primary semiconductor chip fiducial 50 includes multiple
fiducials, illustratively primary semiconductor chip fiducial 52A
and primary semiconductor chip fiducial 52B. Each of primary
semiconductor chip fiducial 52A and primary semiconductor chip
fiducial 52B are shown as having an unbroken circular diameter 54A,
54B respectively. In other embodiments, the unbroken circular
diameter 54A, 54B of each of 52A and 52B may be approximated by
non-intersecting curves having the same center of curvature and
either the same or differing diameters.
[0048] Further, as shown, primary semiconductor chip fiducials 50
are positioned between lower face 19 and upper face 17 of
semiconductor chip 10. In embodiments, each of primary
semiconductor chip fiducial 52A and primary semiconductor chip
fiducial 52B are at the same height in z-direction 30. In
embodiments, primary semiconductor chip fiducial 52A and primary
semiconductor chip fiducial 52B are at differing heights in
z-direction 30. In embodiments, primary semiconductor chip fiducial
52A and primary semiconductor chip fiducial 52B are vertically
aligned with optical component 12 and formed in the same layer of
semiconductor chip 10 as optical component 12. Other exemplary
primary fiducials may be used. In embodiments, one or both of
primary semiconductor chip fiducial 52A and primary semiconductor
chip fiducial 52B forms part of lower face 19 of semiconductor chip
10 or upper face 17 of semiconductor chip 10.
[0049] With alignment system 100, circular diameter 74A of primary
semiconductor chip fiducial 72A, circular diameter 74B of primary
semiconductor chip fiducial 72B, circular diameter 54A of primary
semiconductor chip fiducial 52A, and circular diameter 54B of
primary semiconductor chip fiducial 52B, are visible by camera 106.
Referring to FIG. 9, when optical component 12 is aligned to
optical component 22, circular diameter 74A is concentric with
circular diameter 54A and circular diameter 74B is concentric with
circular diameter 54B. In other embodiments, other arrangements of
circular diameter 74A and circular diameter 54A or circular
diameter 74B and circular diameter 54B may indicate alignment of
optical component 12 to optical component 22. Other exemplary
arrangements, include an known offset between the centers or other
features of primary semiconductor chip fiducial 52A and primary
semiconductor chip fiducial 72A or primary semiconductor chip
fiducial 52B and primary semiconductor chip fiducial 72B. With two
fiducials for each of at least one primary semiconductor chip
fiducial 50 of semiconductor chip 10 and at least one primary
semiconductor chip fiducial 70 of semiconductor chip 20, optical
component 12 may be aligned to optical component 22 in both
x-direction 32 and y-direction 34 with alignment system 100. In
embodiments including a single fiducial for each of at least one
primary semiconductor chip fiducial 50 and at least one primary
semiconductor chip fiducial 70, optical component 12 may be aligned
to optical component 22 only angularly.
[0050] In embodiments, the accuracy of alignment optical component
12 to optical component 22 is limited due to the need to use longer
wavelengths to transmit through the silicon substrates of
semiconductor chip 10 and semiconductor chip 20. As explained
herein, the accuracy of alignment system 100 may be improved by
using feature information of primary semiconductor chip fiducial 50
to determine at least one secondary semiconductor chip fiducial of
semiconductor chip 10 and by using feature information of primary
semiconductor chip fiducial 70 to determine at least one secondary
semiconductor chip fiducial of semiconductor chip 20. Further,
alignment system 100 may use a first wavelength to identify each of
at least one primary semiconductor chip fiducial 50 and at least
one primary semiconductor chip fiducial 70 and a second wavelength
to locate the feature information of at least one primary
semiconductor chip fiducial 50 and at least one primary
semiconductor chip fiducial 70, the second wavelength being shorter
than the first wavelength. Exemplary feature information includes
circular diameter 74A of primary semiconductor chip fiducial 72A,
circular diameter 74B of primary semiconductor chip fiducial 72B,
circular diameter 54A of primary semiconductor chip fiducial 52A,
and circular diameter 54B of primary semiconductor chip fiducial
52B.
[0051] Referring to FIG. 11, an exemplary processing sequence 250
of alignment logic 200 is illustrated. Processing sequence 250
alters the position of semiconductor chip 10 relative to
semiconductor chip 20 with positioning system 102 to align optical
component 12 carried by semiconductor chip 10 relative to optical
component 22 carried by semiconductor chip 20 in x-direction 32 and
in y-direction 34. Processing sequence 250 initially positions
optical component 12 of semiconductor chip 10 relative to optical
component 22 of semiconductor chip 20, as represented by block
252.
[0052] The at least one primary semiconductor chip fiducial 50 of
semiconductor chip 10 is detected, as represented by block 254, and
the at least one primary semiconductor chip fiducial 70 of
semiconductor chip 20 is detected, as represented by block 256. The
detection of at least one primary semiconductor chip fiducial 50
and at least one primary semiconductor chip fiducial 70 is
accomplished based on images received from camera 106. In the
illustrative embodiments of FIGS. 5-8, each of circular diameter
74A of primary semiconductor chip fiducial 72A, circular diameter
74B of primary semiconductor chip fiducial 72B, circular diameter
54A of primary semiconductor chip fiducial 52A, and circular
diameter 54B of primary semiconductor chip fiducial 52B is detected
by analysis of images captured by camera 106.
[0053] Based on feature information of at least one primary
semiconductor chip fiducial 50, alignment logic 200 determines at
least one secondary semiconductor chip fiducial associated with
optical component 12 of semiconductor chip 10, as represented by
block 258, and at least one secondary semiconductor chip fiducial
associated with optical component 22 of semiconductor chip 20, as
represented by block 260.
[0054] Referring to FIG. 12, an unbroken circular diameter 54A of
primary semiconductor chip fiducial 52A and unbroken circular
diameter 74A of primary semiconductor chip fiducial 72A are
illustrated. Further, a secondary semiconductor chip fiducial 56A
determined by alignment logic 200 based on unbroken circular
diameter 54A of primary semiconductor chip fiducial 52A and a
secondary semiconductor chip fiducial 76A determined by alignment
logic 200 based on unbroken circular diameter 74A of primary
semiconductor chip fiducial 72A are shown. In embodiments, for each
of unbroken circular diameter 54A and unbroken circular diameter
74A, alignment logic 200 locates a number of points lying on the
respective unbroken circular diameter 54A and unbroken circular
diameter 74A and then fits those points to a circle by minimizing
the average offset of each point from the fit circle. Upon
determining the best fit circle, alignment logic 200 is able to
locate a center of the circle fit to the points of unbroken
circular diameter 54A, the center being determined secondary
semiconductor chip fiducial 56A, and is able to locate a center of
the circle fit to the points of unbroken circular diameter 74A, the
center being determined secondary semiconductor chip fiducial 76A.
By having a symmetrical feature for primary semiconductor chip
fiducial 52A and primary semiconductor chip fiducial 72A,
illustratively a circular feature, the accuracy of alignment system
100 may be improved because the positioning of points around
determined secondary semiconductor chip fiducial 56A and determined
secondary semiconductor chip fiducial 76A negates the resolving
limit of the vision system, camera 106, of alignment system 100. By
having different diameters for unbroken circular diameter 54A and
unbroken circular diameter 74A, alignment system 100 is always able
to independently determine the position of determined secondary
semiconductor chip fiducial 56A and determined secondary
semiconductor chip fiducial 76A.
[0055] Returning to FIG. 11, alignment logic 200 reviews the
locations of determined secondary semiconductor chip fiducial 56A
and determined secondary semiconductor chip fiducial 76A to
determine if their relative locations indicate that first optical
component 12 of first semiconductor chip 10 is aligned with second
optical component 22 of second semiconductor chip 20, as
represented by block 262. In embodiments, first optical component
12 of first semiconductor chip 10 is aligned with second optical
component 22 of second semiconductor chip 20 when determined
secondary semiconductor chip fiducial 56A is at the same position
as, vertically aligned with, determined secondary semiconductor
chip fiducial 76A. As shown in FIG. 12, determined secondary
semiconductor chip fiducial 56A is offset from determined secondary
semiconductor chip fiducial 76A in both x-direction 32 and
y-direction 34. Based on the offset of determined secondary
semiconductor chip fiducial 56A from determined secondary
semiconductor chip fiducial 76A in both x-direction 32 and
y-direction 34, alignment logic 200 controls positioning system 102
to move determined secondary semiconductor chip fiducial 56A to the
same location as determined secondary semiconductor chip fiducial
76A, as represented by block 264. For example and referring to FIG.
13, alignment logic 200 through positioning system 102 moves one of
first semiconductor chip 10 and second semiconductor chip 20 to
eliminate the offset between determined secondary semiconductor
chip fiducial 56A and determined secondary semiconductor chip
fiducial 76A in x-direction 32, but the offset in y-direction 34
remains. Alignment logic 200 next through positioning system 102
moves one of first semiconductor chip 10 and second semiconductor
chip 20 to eliminate the offset between determined secondary
semiconductor chip fiducial 56A and determined secondary
semiconductor chip fiducial 76A in y-direction 34, as shown is FIG.
14. In FIG. 14, determined secondary semiconductor chip fiducial
56A and determined secondary semiconductor chip fiducial 76A are at
the same location which indicates that first optical component 12
of first semiconductor chip 10 is aligned with second optical
component 22 of second semiconductor chip 20 and the alignment
process is complete, as represented by block 266 in FIG. 11. In
other embodiments, first optical component 12 of first
semiconductor chip 10 is aligned with second optical component 22
of second semiconductor chip 20 when a known offset in one or both
of x-direction 32 and y-direction 34 is present. If this is the
case, alignment logic 200 will move with positioning system 102 one
of first semiconductor chip 10 and second semiconductor chip 20
provide the known offset as part of processing sequence 250.
[0056] In embodiments, alignment logic 200 monitors changes in the
position of determined secondary semiconductor chip fiducial 56A
and determined secondary semiconductor chip fiducial 76A compared
to commanded movements of positioning system 102 to monitor the
accuracy of the movements of positioning system 102 and to provide
an indication to an operator of an issue with the accuracy or
operation of alignment system 100. In embodiments, the positions of
each determined secondary semiconductor chip fiducial 56A and
determined secondary semiconductor chip fiducial 76A may be
determined at multiple wavelengths to determine the accuracy of the
alignment at each wavelength.
[0057] Referring to FIGS. 15-17, an example is provided. Referring
to FIG. 17, a first semiconductor chip 300 includes a semiconductor
laser 302 and a second semiconductor chip 304 includes a photonic
integrated circuit (PIC) 306. As shown in FIG. 17, first
semiconductor chip 300 is positioned on top of second semiconductor
chip 304 and is to be positioned to align semiconductor laser 302
with photonic integrated circuit 306.
[0058] First semiconductor chip 300 includes a primary
semiconductor chip fiducial 308 and second semiconductor chip 304
includes a primary semiconductor fiducial 310. As shown in FIG. 17,
primary semiconductor chip fiducial 308 is a recess and primary
semiconductor fiducial 310 is a protrusion. Primary semiconductor
fiducial 310 nests inside of primary semiconductor chip fiducial
308. The relative sizes of primary semiconductor chip fiducial 308
and primary semiconductor fiducial 310 are selected to provide
movement of first semiconductor chip 300 relative to second
semiconductor chip 304 in x-direction 32 and y-direction 34.
[0059] Referring to FIG. 15, a top view of second semiconductor
chip 304 is shown. Primary semiconductor fiducial 310 includes
multiple fiducials, illustratively primary semiconductor chip
fiducial 320A and primary semiconductor chip fiducial 320B. Each of
primary semiconductor chip fiducial 320A and primary semiconductor
chip fiducial 320B are shown as having an unbroken circular
diameter 322A, 322B respectively. In other embodiments, the
unbroken circular diameter 322A, 322B of each of 322A and 322B may
be approximated by non-intersecting curves having the same center
of curvature and either the same or differing diameters. Primary
semiconductor chip fiducial 320A and primary semiconductor chip
fiducial 320B are formed in a waveguide layer of second
semiconductor chip 304 which is the same layer as a waveguide of
photonic integrated circuit 306. Primary semiconductor chip
fiducial 320A and primary semiconductor chip fiducial 320B are
protrusions that are nested with corresponding recesses on first
semiconductor chip 300.
[0060] Referring to FIG. 16, a bottom view of first semiconductor
chip 300 is shown. Primary semiconductor chip fiducial 308 includes
multiple fiducials, illustratively primary semiconductor chip
fiducial 330A and primary semiconductor chip fiducial 330B. Each of
primary semiconductor chip fiducial 330A and primary semiconductor
chip fiducial 330B are shown as having non-intersecting curves 332A
and 334A for primary semiconductor chip fiducial 330A and
non-intersecting curves 332B and 334B for primary semiconductor
chip fiducial 330B. In the illustrated embodiment, non-intersecting
curves 332A and 334A have the same center of curvature and the same
diameter and non-intersecting curves 332B and 334B have the same
center of curvature and the same diameter. Primary semiconductor
chip fiducial 330A and primary semiconductor chip fiducial 330B are
formed in an etch layer of first semiconductor chip 300. Primary
semiconductor chip fiducial 330A and primary semiconductor chip
fiducial 330B are recesses which receive the protrusions of
unbroken circular diameter 322A and unbroken circular diameter
322B.
[0061] While this invention has been described as having exemplary
designs, the present invention can be further modified within the
spirit and scope of this disclosure. This application is therefore
intended to cover any variations, uses, or adaptations of the
invention using its general principles. Further, this application
is intended to cover such departures from the present disclosure as
come within known or customary practice in the art to which this
invention pertains.
* * * * *