U.S. patent application number 13/162802 was filed with the patent office on 2011-10-06 for multiple die structure and method of forming a connection between first and second dies in same.
Invention is credited to Gloria Alejandra Camacho-Bragado, Lakshmi Supriya.
Application Number | 20110240349 13/162802 |
Document ID | / |
Family ID | 42036799 |
Filed Date | 2011-10-06 |
United States Patent
Application |
20110240349 |
Kind Code |
A1 |
Supriya; Lakshmi ; et
al. |
October 6, 2011 |
MULTIPLE DIE STRUCTURE AND METHOD OF FORMING A CONNECTION BETWEEN
FIRST AND SECOND DIES IN SAME
Abstract
A multiple die structure includes a first die (110), a second
die (120), a carbon nanotube (130) having a first end (131) in
physical contact with the first die and having a second end (132)
in physical contact with the second die, and an electrically
conductive material (240) in physical contact with the first end of
the carbon nanotube and in physical contact with the first die.
Forming a connection between the first die and the second die can
include providing a connection structure (400, 500, 600, 900) in
which the electrically conductive material is adjacent to the
carbon nanotube, placing the connection structure adjacent to the
first die and to the second die, and bonding the first die and the
second die to the connection structure.
Inventors: |
Supriya; Lakshmi;
(Arlington, MA) ; Camacho-Bragado; Gloria Alejandra;
(Chicago, IL) |
Family ID: |
42036799 |
Appl. No.: |
13/162802 |
Filed: |
June 17, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12284531 |
Sep 22, 2008 |
|
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13162802 |
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Current U.S.
Class: |
174/257 ;
977/742 |
Current CPC
Class: |
H01L 24/16 20130101;
H01L 2224/11003 20130101; H01L 21/6835 20130101; H01L 2224/81191
20130101; H01L 24/11 20130101; H01L 2924/01006 20130101; H01L
2924/01047 20130101; H01L 2924/01082 20130101; H01L 2224/81203
20130101; H01L 2924/01046 20130101; H01L 2225/06513 20130101; H01L
24/12 20130101; H01L 24/81 20130101; H01L 2924/01033 20130101; H01L
2224/13099 20130101; H01L 2924/014 20130101; H01L 2224/13025
20130101; H01L 25/0657 20130101; H01L 23/481 20130101; H01L
2224/114 20130101; H01L 2924/01078 20130101; H01L 2924/01029
20130101; H01L 2225/06541 20130101; H01L 2924/01075 20130101; H01L
23/53276 20130101; H01L 2224/116 20130101; H01L 2224/81801
20130101; H01L 2924/01327 20130101; H01L 2924/01079 20130101 |
Class at
Publication: |
174/257 ;
977/742 |
International
Class: |
H05K 1/09 20060101
H05K001/09 |
Claims
1. A multiple die structure comprising: a first die having an
associated first connection structure; a second die having an
associated second connection structure; a carbon nanotube having a
first end adjacent to the first connection structure and having a
second end adjacent to the second connection structure; and an
electrically conductive material in physical contact with the first
end of the carbon nanotube and in physical contact with the first
connection structure.
2. The multiple die structure of claim 1 wherein: the first
connection structure comprises a first metal; and the electrically
conductive material also comprises the first metal.
3. The multiple die structure of claim 2 wherein: the first
connection structure is a first copper pad and the second
connection structure is a second copper pad; and the electrically
conductive material comprises copper.
4. The multiple die structure of claim 1 wherein: the electrically
conductive material is in physical contact with the first end and
the second end of the carbon nanotube and also in physical contact
with the first connection structure and the second connection
structure.
Description
CLAIM OF PRIORITY
[0001] This application is a divisional of U.S. patent application
Ser. No. 12/284,531, now U.S. Pat. No. ______, which was filed on
Sep. 22, 2008.
FIELD OF THE INVENTION
[0002] The disclosed embodiments of the invention relate generally
to die to die interconnects, and relate more particularly to the
low-temperature formation and resulting structure of such
interconnects.
BACKGROUND OF THE INVENTION
[0003] Computer systems increasingly employ stacked-die
architectures because of the space savings and other advantages
they offer. Copper-copper interconnects are desirable in stacked
die architectures because of copper's high current carrying
capability, which leads to low electromigration levels and thus
enables power to be efficiently delivered through the entire stack.
(Copper will sometimes be referred to herein using its abbreviation
"Cu.") Unfortunately, no low temperature method for forming Cu--Cu
interconnects currently exists. Instead, current practice typically
involves depositing a solder material onto electrically conductive
features (e.g., copper pads or bumps) attached to one or both dies
and the die to die interconnection is made via the solder. However,
these techniques tend to cause various problems, including
problematic electromigration levels, poor solder joint reliability,
and flux-associated contamination issues.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] The disclosed embodiments will be better understood from a
reading of the following detailed description, taken in conjunction
with the accompanying figures in the drawings in which:
[0005] FIGS. 1 and 2 are cross-sectional views of a multiple die
structure according to an embodiment of the invention;
[0006] FIG. 3 is a flowchart illustrating a method of forming a
connection between a first die and a second die of a multiple die
structure according to an embodiment of the invention;
[0007] FIGS. 4-6 are cross-sectional views of connection structures
according to various embodiments of the invention;
[0008] FIG. 7 is a flowchart illustrating a method of forming a
connection between a first die and a second die of a multiple die
structure according to another embodiment of the invention;
[0009] FIG. 8 is a flowchart illustrating a method of forming a
connection between a first die and a second die of a multiple die
structure according to another embodiment of the invention;
[0010] FIG. 9 is a cross-sectional view of another connection
structure according to an embodiment of the invention; and
[0011] FIGS. 10-14 are cross-sectional views of a multiple die
structure at various points in its manufacturing process according
to an embodiment of the invention.
[0012] For simplicity and clarity of illustration, the drawing
figures illustrate the general manner of construction, and
descriptions and details of well-known features and techniques may
be omitted to avoid unnecessarily obscuring the discussion of the
described embodiments of the invention. Additionally, elements in
the drawing figures are not necessarily drawn to scale. For
example, the dimensions of some of the elements in the figures may
be exaggerated relative to other elements to help improve
understanding of embodiments of the present invention. The same
reference numerals in different figures denote the same elements,
while similar reference numerals may, but do not necessarily,
denote similar elements.
[0013] The terms "first," "second," "third," "fourth," and the like
in the description and in the claims, if any, are used for
distinguishing between similar elements and not necessarily for
describing a particular sequential or chronological order. It is to
be understood that the terms so used are interchangeable under
appropriate circumstances such that the embodiments of the
invention described herein are, for example, capable of operation
in sequences other than those illustrated or otherwise described
herein. Similarly, if a method is described herein as comprising a
series of steps, the order of such steps as presented herein is not
necessarily the only order in which such steps may be performed,
and certain of the stated steps may possibly be omitted and/or
certain other steps not described herein may possibly be added to
the method. Furthermore, the terms "comprise," "include," "have,"
and any variations thereof, are intended to cover a non-exclusive
inclusion, such that a process, method, article, or apparatus that
comprises a list of elements is not necessarily limited to those
elements, but may include other elements not expressly listed or
inherent to such process, method, article, or apparatus.
[0014] The terms "left," "right," "front," "back," "top," "bottom,"
"over," "under," and the like in the description and in the claims,
if any, are used for descriptive purposes and not necessarily for
describing permanent relative positions. It is to be understood
that the terms so used are interchangeable under appropriate
circumstances such that the embodiments of the invention described
herein are, for example, capable of operation in other orientations
than those illustrated or otherwise described herein. The term
"coupled," as used herein, is defined as directly or indirectly
connected in an electrical or non-electrical manner. Objects
described herein as being "adjacent to" each other may be in
physical contact with each other, in close proximity to each other,
or in the same general region or area as each other, as appropriate
for the context in which the phrase is used. Occurrences of the
phrase "in one embodiment" herein do not necessarily all refer to
the same embodiment.
DETAILED DESCRIPTION OF THE DRAWINGS
[0015] In one embodiment of the invention, a multiple die structure
comprising a first die having an associated first connection
structure, a second die having an associated second connection
structure, a carbon nanotube (CNT) having a first end in physical
contact with the first connection structure and having a second end
in physical contact with the second connection structure, and an
electrically conductive material in physical contact with the first
end of the CNT and in physical contact with the first connection
structure. The CNT may be multi-walled or single-walled. In an
embodiment, forming a connection between the first die and the
second die of the multiple die structure comprises providing a
connection structure comprising a metal adjacent to a CNT, placing
the connection structure adjacent to the first die in order to form
a first interface between the first die and the connection
structure, placing the second die adjacent to the connection
structure in order to form a second interface between the second
die and the connection structure, and bonding the first die and the
second die to the connection structure.
[0016] Because CNTs are used as part of the interconnect material,
embodiments of the invention enable the formation of die to die
interconnects at room temperature with the use of a small voltage.
It is known in the art that metal nanoparticles exhibit a lower
melting temperature and lower latent heat of fusion than do bulk
metals. Since the inner cavity of the CNT is small the metal inside
will present a low melting temperature and thus a low voltage
(e.g., 0.5 volts) will cause a temperature increase sufficient to
melt and release the metal. The molten metal will readily contact
the bump and cool down to form a Cu--Cu (or other metal-metal)
joint.
[0017] The use of CNTs eliminates electromigration issues, improves
joint reliability since CNTs are mechanically strong and compliant,
and eliminates the need to use flux. Since there is no solder at
the interfaces the joint formed will be relatively strong because
the absence of intermetallic layers improves joint reliability.
[0018] Referring now to the drawings, FIG. 1 is a cross-sectional
view of a multiple die structure 100 according to an embodiment of
the invention. FIG. 2 is a detail view of a portion of FIG. 1. As
illustrated in FIGS. 1 and 2, multiple die structure 100 comprises
a die 110 having an associated connection structure 111, a die 120
having an associated connection structure 121, a carbon nanotube
130 having an end 231 adjacent to connection structure 111 and
having an end 232 adjacent to connection structure 121, and an
electrically conductive material 240 in physical contact with end
231 of carbon nanotube 130 and in physical contact with connection
structure 111. In the illustrated embodiment die 110 and die 120
are stacked in a vertical relationship. Other embodiments may
feature other die arrangements, including planar (non-stacked)
arrangements.
[0019] In the illustrated embodiment, electrically conductive
material 240, which as an example may be copper or another metal,
is in physical contact with end 231 and with end 232 of carbon
nanotube 130 and also in physical contact with connection structure
111 and with connection structure 121. In a non-illustrated
embodiment, electrically conductive material 240 is located only at
one end or the other, with the joint to be formed at the end
lacking electrically conductive material 240 to be formed in some
other fashion as dictated by the particular embodiment.
[0020] Multiple die structure 100 further comprises a substrate 150
and electrically conductive pads 160 and solder bumps 170 that
connect die 110 to substrate 150. (In a non-illustrated embodiment,
solder bumps 170 could be replaced with a CNT-based interconnect
using copper bumps or the like.) Dies 110 and 120 each comprise
circuitry 180 that may include transistors and the like. Die 110
also comprises through silicon vias (TSVs) 190.
[0021] As an example, connection structures 111 and 121 can
comprise a copper pad, a copper bump, or the like. As another
example, electrically conductive pads 160 can likewise comprise
copper, as can electrically conductive material 240. It should be
noted, in fact, that an embodiment in which connection structures
111 and 121, electrically conductive pads 160, and electrically
conductive material 240 each comprise copper may well offer
performance that is superior to other embodiments. One reason for
this may be that since there is only one metal constituting the
joint no intermetallic compounds are formed and thus the
reliability of the joint is expected to be higher than regular
solder-Cu joints. Other reasons contributing to the superior
performance of copper have been mentioned above.
[0022] It should be noted further that many of the foregoing
performance advantages may be obtained with materials other than
copper provided that the same material that is used for connection
structures 111 and 121 is also used for electrically conductive
pads 160 and electrically conductive material 240. It should also
be noted that embodiments where connection structures 111 and 121,
electrically conductive pads 160, and electrically conductive
material 240 are not all made of the same material may still offer
at least some of the advantages offered by embodiments where each
of the stated components are made of the same material.
[0023] FIG. 3 is a flowchart illustrating a method 300 of forming a
connection between a first die and a second die of a multiple die
structure according to an embodiment of the invention. In at least
one embodiment, the connection is both a physical and an electrical
connection. As an example, method 300 may result in the formation
of a multiple die structure that is similar to multiple die
structure 100 that is shown in FIG. 1.
[0024] A step 310 of method 300 is to provide a connection
structure comprising an electrically conductive material adjacent
to a carbon nanotube. As an example, the electrically conductive
material and the carbon nanotube can be similar to, respectively,
electrically conductive material 240 and carbon nanotube 130, both
of which are shown in at least one of FIGS. 1 and 2.
[0025] A step 320 of method 300 is to place the connection
structure adjacent to the first die in order to form a first
interface between the first die and the connection structure.
[0026] A step 330 of method 300 is to place the second die adjacent
to the connection structure in order to form a second interface
between the second die and the connection structure.
[0027] A step 340 of method 300 is to bond the first die and the
second die to the connection structure. Multiple methods for
accomplishing the bonding of step 340 are contemplated. At least
some of these are somewhat dependent on certain physical
characteristics of the carbon nanotube, as will be further
discussed in the following paragraphs.
[0028] In one embodiment, the carbon nanotube comprises an interior
space and the electrically conductive material (e.g., a metal) is
contained within the interior space. This is shown in FIG. 4, which
is a cross-sectional view of a connection structure 400 according
to an embodiment of the invention. It should be noted that the
connection structure introduced above in conjunction with step 310
can, as an example, be similar to connection structure 400.
[0029] As illustrated in FIG. 4, connection structure 400 comprises
a carbon nanotube 410 having an interior space 411 with an
electrically conductive material 420 contained within interior
space 411. As an example, electrically conductive material 420 can
comprise metals including copper, nickel, platinum, palladium, and
any other metals that may act as a catalyst for growing CNTs.
Accordingly, electrically conductive material 240, first introduced
above in the discussion of FIG. 2, can comprise any of the
foregoing metals.
[0030] In one embodiment, and assuming a structure such as that
shown in FIG. 4, step 340 comprises applying a first voltage across
the first interface in order to cause at least a portion of the
metal to flow out of the carbon nanotube and contact the first die
at the first interface, and bonding the second die to the
connection structure comprises applying a second voltage across the
second interface in order to cause at least a portion of the metal
to flow out of the carbon nanotube and contact the second die at
the second interface. More specifically, the portion of the metal
melts, flows out of the carbon nanotube such that it is in physical
contact with both the carbon nanotube and the first or second die
across the first or second interface, and then cools and
re-solidifies in order to bond the carbon nanotube to the first or
second die. As an example, the direction in which the metal flows
can be controlled by manipulating the polarity of the applied
voltage. As another example, the magnitude of the voltage can be
between approximately 0.5 volts and approximately 5 to 10 volts.
Certain embodiments may require or benefit from even higher
voltages.
[0031] In another embodiment, the connection structure comprises a
metal nanowire/carbon nanotube hybrid structure. An example of this
is shown in FIG. 5, which is a cross-sectional view of a connection
structure 500 according to an embodiment of the invention. It
should be noted that the connection structure introduced above in
conjunction with step 310 can, as an example, be similar to
connection structure 500.
[0032] As illustrated in FIG. 5, connection structure 500 comprises
a carbon nanotube 510 located between a metal nanowire section 520
and a metal nanowire section 530. Accordingly, the metal of
connection structure 500 is located at least at a first end and at
a second end of the carbon nanotube. In the illustrated embodiment,
the metal is located next to the ends of carbon nanotube 510 with
no portion of the metal located inside the carbon nanotube. In a
non-illustrated embodiment, either or both ends of carbon nanotube
510 may have some metal from the adjacent metal nanowire section,
or a different metal, located inside. In a different
non-illustrated embodiment, connection structure 500 comprises
carbon nanotube 510 and one (but not both) of metal nanowire
sections 520 and 530. As an example, metal nanowire sections 520
and 530 can comprise silver, gold, nickel, platinum, palladium,
copper, or the like.
[0033] In another embodiment, the connection structure comprises a
combination of the connection structures that are illustrated in
FIGS. 4 and 5. An example of this is shown in FIG. 6, which is a
cross-sectional view of a connection structure 600 according to an
embodiment of the invention. It should be noted that the connection
structure introduced above in conjunction with step 310 can, as an
example, be similar to connection structure 600.
[0034] As illustrated in FIG. 6, connection structure 600 comprises
a carbon nanotube 610 having an interior space 611 with an
electrically conductive material 620 contained within interior
space 611. As an example, electrically conductive material 620 can
be similar to electrically conductive material 420 that is shown in
FIG. 4. Carbon nanotube 610 is adjacent to a metal nanowire section
630. Accordingly, the metal of connection structure 600 is located
at least at a first end of the carbon nanotube (e.g., inside the
carbon nanotube) and at a second end of the carbon nanotube (e.g.,
either adjacent to the end of as well as inside the carbon nanotube
or else adjacent to the end of but not inside the carbon
nanotube).
[0035] In one embodiment, and assuming a structure such as that
shown in FIG. 5 or 6 (or the described alternatives), step 340
comprises applying a first voltage across the first interface and a
second voltage across the second interface in order to melt the
metal such that the first die and the second die become bonded to
the carbon nanotube.
[0036] FIG. 7 is a flowchart illustrating a method 700 of forming a
connection between a first die and a second die of a multiple die
structure according to an embodiment of the invention. In at least
one embodiment, the connection is both a physical and an electrical
connection. As an example, method 700 may result in the formation
of a multiple die structure that is similar to multiple die
structure 100 that is shown in FIG. 1.
[0037] A step 710 of method 700 is to form (e.g., grow) on the
first die a carbon nanotube comprising an interior space containing
a metal. As an example, the carbon nanotube can be similar to
carbon nanotube 410 that is shown in FIG. 4. In one embodiment,
step 710 comprises growing the carbon nanotube using
plasma-assisted chemical vapor deposition. In the same or another
embodiment, step 710 comprises (or further comprises) using an
alkali-doped catalyst. In the same or another embodiment, step 710
comprises growing the carbon nanotube only on a metallized area of
the first die. This may be accomplished using techniques known in
the art, such as photolithography, physical masks, and the
like.
[0038] A step 720 of method 700 is to place the second die adjacent
to the first die in order to form an interface between the second
die and the carbon nanotube.
[0039] A step 730 of method 700 is to cause at least a portion of
the metal to flow out of the carbon nanotube and contact the second
die at the interface, thereby forming the connection between the
first die and the second die. In one embodiment, step 730 comprises
applying a voltage difference across the interface.
[0040] FIG. 8 is a flowchart illustrating a method 800 of forming a
connection between a first die and a second die of a multiple die
structure according to an embodiment of the invention. In at least
one embodiment, the connection is both a physical and an electrical
connection. As an example, method 800 may result in the formation
of a multiple die structure that is similar to multiple die
structure 100 that is shown in FIG. 1.
[0041] A step 810 of method 800 is to provide a connection
structure to which an electrode is attached, the connection
structure comprising a first metal section containing a first metal
and further comprising at least one carbon nanotube. As an example,
the connection structure can contain a number of connections
structures that are similar to connection structure 500 that is
shown in FIG. 5 (which, as may be seen in the figure and as is
described above, further includes a second metal section adjacent
to the carbon nanotube, with the second metal section containing a
second metal). As another example, the connection structure can
contain a number of connection structures that are similar to
connection structure 600 that is shown in FIG. 6 (which, as may be
seen in the figure and as described above, comprises a metal-filled
carbon nanotube and a single metal section).
[0042] FIG. 9 is a cross-sectional view of another connection
structure--connection structure 900--according to an embodiment of
the invention and that may be used in conjunction with method 800
(or with other methods according to other embodiments of the
invention). As illustrated in FIG. 9, connection structure 900
comprises a template 910 to which an electrode 920 is attached.
Template 910 provides spaces 911 in which a metal nanowire/carbon
nanotube hybrid structure--similar to that shown in FIG. 5--may be
formed. As depicted in FIG. 9, template 910 contains a plurality of
such metal nanowire/carbon nanotube hybrid structures. In other
embodiments, the template may instead contain connection structures
that are similar to those shown in FIGS. 4 and 6, or may contain
other types of connection structures similar to those described
herein.
[0043] In one embodiment, providing a connection structure such as
connection structure 900 begins with providing a series of anodic
alumina (or similar) structures to serve as the template. Dense
arrays of hybrid CNTs are easily fabricated using alumina
templates, as known in the art. The template can be kept for easy
manipulation of the arrays and etched away (or otherwise removed)
once the CNTs are in place, as described below, or it can be
removed immediately upon completion of CNT fabrication. After the
template is provided the electrode is then plated or otherwise
deposited along one edge of the template and the first metal is
plated or otherwise formed within the template adjacent to the
electrode. The next step is to grow the carbon nanotubes (e.g., by
using chemical vapor deposition (CVD) techniques or the like)
within the template adjacent to the first metal. In particular
embodiments, providing the connection structure further comprises
plating a second metal section within the template adjacent to the
carbon nanotubes.
[0044] The foregoing paragraph has disclosed one method of
fabricating a bundle of aligned CNTs (which are described as part
of a hybrid metal-CNT-metal structure). Another method of
fabricating bundles of aligned CNTs is to deposit an alkali-doped
copper catalyst on one of the dies and to then grow CNTs using a
plasma enhanced CVD (PECVD) method. This process produces
copper-filled CNTs like those shown in FIG. 4 that are fabricated
directly on the die itself. Alternatively, a similar process could
be used to grow and pattern CNTs elsewhere, after which the CNTs
could be transferred onto the die. In this alternative process, the
CNTs are grown on a different substrate (such as silicon) using
plasma-assisted CVD on alkali doped catalysts and are patterned
analogous to the die bump field. (Or the CNTs may be formed using
other methods such as the HiPCO (high pressure catalytic
decomposition of carbon monoxide) method or the like.) The tubes
are then aligned over a die that is bonded to the substrate and a
voltage is applied. As with other embodiments, the metal in the
CNTs flows out to form a joint. Since the resulting adhesion is
much stronger than that to the substrate on which it was grown, the
CNTs are transferred to the die. A second die is then placed over
the CNTs and a reverse voltage is applied which causes the rest of
the metal inside to flow out and bond to the second die. Since the
rate of flow is very slow, a good control of the amount of the
metal that comes out can be exercised, ensuring there is enough
metal to bond to both sides. Another version of this embodiment is
to have CNTs attached to both die and when the dies are bonded
together it is because of the interconnection of the CNTs.
[0045] A step 820 of method 800 is to place the connection
structure on the first die in order to form a first interface
between the first die and the connection structure. In embodiments
where the connection structure includes a template (e.g., similar
to template 910), step 820 can comprise placing the template on the
first die. A result of the performance of step 820 according to an
embodiment of the invention is shown in FIG. 10, which is a
cross-sectional view of a multiple die structure 1000 at a
particular point in its manufacturing process according to an
embodiment of the invention. As illustrated in FIG. 10, multiple
die structure 1000 comprises die 110 and associated connection
structure 111, substrate 150, electrically conductive pads 160,
solder bumps 170, circuitry 180, and TSVs 190. In accordance with
step 820 of method 800, connection structure 900 has been placed on
die 110 in order to form an interface 1010 between die 110 and
connection structure 900. Note that in the illustrated embodiment
electrode 920 forms a continuous top layer of connection structure
900. In one embodiment electrode 920 comprises silver.
[0046] A step 830 of method 800 is to apply a first voltage across
the first interface in order to melt the first metal such that at
least a first portion of the carbon nanotube becomes bonded to the
first die. A result of the performance of step 830 according to an
embodiment of the invention is shown in FIG. 11, which is a
cross-sectional view of multiple die structure 1000 at a particular
point in its manufacturing process according to an embodiment of
the invention. As illustrated in FIG. 11, a voltage source 1110 has
been electrically connected to multiple die structure 1000 using
wires 1120 in such a way that a voltage has been applied to
electrode 920 and across interface 1010 in accordance with step
830. As an example, one lead (wire) of voltage source 1110 could be
connected to electrode 920 and the other lead could be connected to
the socket, and the current flow could take place over existing
electrical pathways. As a result of this voltage, at least a
portion of some of metal nanowire sections 530 have melted and then
re-solidified across interface 1010 to form bond regions 1130 that
bond carbon nanotube 510 to die 110. As an example, voltage source
1110 can be a direct current (DC) voltage source such as a battery
pack. Two or more separate battery packs could be used where
different polarities are required or desired. Alternatively, an
alternating current (AC) voltage source could be used where there
is a need to reverse polarity.
[0047] It should be noted that the metal nanowire sections 530 that
melt and form bonding regions 1130 are those that are located in
places where the circuit formed by voltage source 1110 and wires
1120 closes, e.g., those that are located at metallized areas of
TSVs 190 (i.e., at connection structure 111). Those that are not in
contact with a metal will not experience the voltage and therefore
will not melt or form a joint.
[0048] In one embodiment, following the performance of step 830
template 910 and electrode 920, along with metal nanowire sections
530 that remain unbonded, are removed. This is shown in FIG. 12,
which is a cross-sectional view of multiple die structure 1000 at a
particular point in its manufacturing process according to an
embodiment of the invention. As an example, such removal may be
accomplished by etching away the targeted features using a diluted
acid solution or the like.
[0049] A step 840 of method 800 is to place the second die adjacent
to the connection structure in order to form a second interface
between the second die and the connection structure. A result of
the performance of step 840 according to an embodiment of the
invention is shown in FIG. 13, which is a cross-sectional view of a
multiple die structure 1000 at a particular point in its
manufacturing process according to an embodiment of the invention.
As illustrated in FIG. 13, and in accordance with step 840, die 120
and associated connection structure 121 have been placed over the
remaining portions of connection structure 900 in order to form an
interface 1310 between die 120 and the remaining portions of
connection structure 900.
[0050] A step 850 of method 800 is to bond the second die to the
connection structure. In one embodiment, step 850 comprises
applying a second voltage across the second interface in order to
melt at least a portion of the second metal such that at least a
portion of the carbon nanotube becomes bonded to the second die.
The voltage can have, but does not have to have, the same magnitude
as the first voltage. A result of the performance of step 850
according to an embodiment of the invention is shown in FIG. 14,
which is a cross-sectional view of multiple die structure 1000 at a
particular point in its manufacturing process according to an
embodiment of the invention. As illustrated in FIG. 14, a voltage
has been applied across interface 1310, or some other action in
accordance with step 850 has taken place, as a result of which at
least a portion of metal nanowire sections 520 have melted and then
re-solidified across interface 1310 to form bond regions 1410 that
bond carbon nanotube 510 to die 210.
[0051] In another embodiment, the carbon nanotubes of the
connection structure may, as mentioned above, be similar to those
shown in FIGS. 4 and 6, in that the carbon nanotubes comprise an
interior space in which the second metal is contained. In that
embodiment, step 850 can comprise applying a second voltage across
the second interface in order to cause at least a portion of the
second metal to flow out of the carbon nanotubes and contact the
second die at the second interface. The second metal, which is then
in physical contact with both the carbon nanotube and the second
die, re-solidifies and forms an electrically conductive joint in
the manner that has been explained above.
[0052] Although the invention has been described with reference to
specific embodiments, it will be understood by those skilled in the
art that various changes may be made without departing from the
spirit or scope of the invention. Accordingly, the disclosure of
embodiments of the invention is intended to be illustrative of the
scope of the invention and is not intended to be limiting. It is
intended that the scope of the invention shall be limited only to
the extent required by the appended claims. For example, to one of
ordinary skill in the art, it will be readily apparent that the
multiple die structure and the related connection structures and
methods discussed herein may be implemented in a variety of
embodiments, and that the foregoing discussion of certain of these
embodiments does not necessarily represent a complete description
of all possible embodiments.
[0053] Additionally, benefits, other advantages, and solutions to
problems have been described with regard to specific embodiments.
The benefits, advantages, solutions to problems, and any element or
elements that may cause any benefit, advantage, or solution to
occur or become more pronounced, however, are not to be construed
as critical, required, or essential features or elements of any or
all of the claims.
[0054] Moreover, embodiments and limitations disclosed herein are
not dedicated to the public under the doctrine of dedication if the
embodiments and/or limitations: (1) are not expressly claimed in
the claims; and (2) are or are potentially equivalents of express
elements and/or limitations in the claims under the doctrine of
equivalents.
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