U.S. patent application number 10/392084 was filed with the patent office on 2004-09-23 for wafer-level inter-connector formation method.
Invention is credited to Iyer, Mahadevan K., Kripesh, Vaidyanathan, Nagarajan, Ranganathan.
Application Number | 20040185593 10/392084 |
Document ID | / |
Family ID | 32927321 |
Filed Date | 2004-09-23 |
United States Patent
Application |
20040185593 |
Kind Code |
A1 |
Kripesh, Vaidyanathan ; et
al. |
September 23, 2004 |
WAFER-LEVEL INTER-CONNECTOR FORMATION METHOD
Abstract
Inter-connectors are typically used for interconnecting
electronic components. Interconnections between electronic
components are generally classified into at least two broad
categories of "relatively permanent" and "readily demountable". A
"readily demountable" connector includes a spring-like contact
structure of one electronic component for connecting to a terminal
of another electronic component. The spring-like contact structure,
also known as an inter-connector, generally requires a certain
amount of contact force to effect reliable pressure contact to a
terminal of an electronic component. Therefore, the shape and
metallurgy of the inter-connector are important factors in
determining the effectiveness of the inter-connector for making
pressure connection to a terminal of the electronic component.
Conventional methods of making such an inter-connector use
lithographic and planarisation methods to "make" the
inter-connectors in segments. This results in the inter-connector
segments having joints therebetween. Metallurgically, the joint
stress due to joining a pair of inter-connector segments and stress
concentration at the joints due forces applied to the
inter-connector can lead to the mechanical failure of the
inter-connector in Mathieu. An embodiment of the invention uses
lithographic techniques and heat treatment methods for forming a
structure channel defining the shape and dimension of an
inter-connector. The structure channel is then used to "mold" a
reproduction of the inter-connector having a single continuous
physical segment.
Inventors: |
Kripesh, Vaidyanathan;
(Singapore, SG) ; Iyer, Mahadevan K.; (Singapore,
SG) ; Nagarajan, Ranganathan; (Singapore,
SG) |
Correspondence
Address: |
NATH & ASSOCIATES
1030 15th STREET
6TH FLOOR
WASHINGTON
DC
20005
US
|
Family ID: |
32927321 |
Appl. No.: |
10/392084 |
Filed: |
March 20, 2003 |
Current U.S.
Class: |
438/52 ;
438/701 |
Current CPC
Class: |
H01L 21/4853
20130101 |
Class at
Publication: |
438/052 ;
438/701 |
International
Class: |
H01L 021/44; H01L
021/4763; H01L 021/00; H01L 021/311 |
Claims
1. An inter-connector formation method for forming an
inter-connector for use as an electro-mechanical connector, the
inter-connector formation method comprising the steps of: forming a
first passage in a first sacrificial layer of a first sacrificial
material, the first sacrificial layer being formed over a portion
of a substrate, the first passage extending from a signal terminal
to an opening in the first sacrificial layer, and the signal
terminal being formed on the substrate; forming a protrusion over
the opening of the first sacrificial layer, the protrusion being of
a second sacrificial material and the second sacrificial material
further extending from the protrusion to the signal terminal;
forming a second passage in a second sacrificial layer of the first
sacrificial material, the second sacrificial layer being formed
over a portion of the second sacrificial layer and the protrusion,
the second passage extending from the protrusion to an opening in
the second sacrificial layer; removing the second sacrificial
material to expose a structure channel extending from the signal
terminal to the opening in the second sacrificial layer, and the
structure channel defining the shape and dimension of the
inter-connector; and depositing a structure material into the
opening of the second sacrificial layer and thereby filling the
structure channel therewith, the structure material taking the
shape and dimension of the structure channel to form the
inter-connector extending from the signal terminal to the opening
in the second sacrificial layer.
2. The inter-connector formation method as in claim 1, further
comprising a step of removing the first sacrificial material to
expose the inter-connector.
3. The inter-connector formation method as in claim 1, the step of
forming a first passage in a first sacrificial layer comprising the
steps of: coating a portion of a surface of the substrate with the
first sacrificial material to form the first sacrificial layer;
patterning the first sacrificial layer to define the opening in the
first sacrificial layer; and removing a portion of the first
sacrificial layer to form the first passage, the first passage
exposing a portion of the signal terminal.
4. The inter-connector formation method as in claim 1, the step of
forming a protrusion over the opening of the first sacrificial
layer comprising the steps of: coating a portion of a surface of
the first sacrificial layer with the second sacrificial material
and thereby filling the first passage with the second sacrificial
material to form a transitional layer; patterning the transitional
layer to define the protrusion; and removing a portion of the
transitional layer to form the protrusion and expose a portion of
the firs sacrificial layer.
5. The inter-connector formation method as in claim 1, the step of
forming a second passage in a second sacrificial layer comprising
the steps of: coating a portion of a surface of the first
sacrificial layer and the protrusion with the first sacrificial
material to form the second sacrificial layer; patterning the
second sacrificial layer to define the opening in the second
sacrificial layer; and removing a portion of the second sacrificial
layer to form the second passage.
6. The inter-connector formation method as in claim 1, the step of
forming a first passage in a first sacrificial layer of a first
sacrificial material comprising a step of: providing the first
sacrificial material for the first sacrificial layer, the first
sacrificial material being polymer-based and having a degradation
temperature.
7. The inter-connector formation method as in claim 6, the step of
forming a protrusion over opening of the first sacrificial layer:
providing the second sacrificial material for forming the
protrusion, the second sacrificial material being polymer-based and
having a degradation temperature.
8. The inter-connector formation method as in claim 7, the step of
providing the second sacrificial material comprising a step of:
providing the second sacrificial material with the degradation
temperature thereof being lower than the degradation temperature of
the first sacrificial material.
9. The inter-connector formation method as in claim 8, the step of
removing the second sacrificial material to expose a structure
channel comprising a step of: heat-treating the second sacrificial
material at the degradation temperature thereof.
10. The inter-connector formation method as in claim 1, the step of
depositing a structure material into the opening of the second
sacrificial comprising a step of: plating the structure channel
with the structure material.
11. The inter-connector formation method as in claim 9, the step of
forming a first passage in a first sacrificial layer comprising a
step of: forming a seed layer between the first sacrificial layer
and the substrate, the seed layer being conductive and formed over
the signal terminal.
12. The inter-connector formation method as in claim 11, the step
of depositing a structure material into the opening of the second
sacrificial comprising a step of: electro-plating the structure
channel with the structure material by initiating a charge build-up
on the signal terminal.
13. The inter-connector formation method as in claim 2, the step of
removing the first sacrificial material to expose the
inter-connector comprising a step of: heat-treating the first
sacrificial material at the degradation temperature thereof, the
first sacrificial material and the second sacrificial material
being polymer-based and each of the first and second sacrificial
material having a degradation temperature, wherein the degradation
temperature of the first sacrificial material is higher than the
degradation temperature of the second sacrificial material.
14. The inter-connector formation method as in claim 1, the step of
depositing a structure material into the opening of the second
sacrificial layer to form the inter-connector comprising a step of:
forming a resiliently biased inter-connector.
15. The inter-connector formation method as in claim 1, the step of
depositing a structure material into the opening of the second
sacrificial layer to form the inter-connector comprising a step of:
forming the inter-connector with a cantilever configuration, the
inter-connector having a fixed end attached to the signal terminal
of the substrate and a free end.
16. The inter-connector formation method as in claim 1, the step of
depositing a structure material into the opening of the second
sacrificial layer to form the inter-connector comprising a step of:
depositing a conductive structure material.
17. The inter-connector formation method as in claim 16, further
comprising a step of: forming a conductive stub at the free end of
the inter-connector.
18. The inter-connector formation method as in claim 17, the step
of forming a conductive stub comprising the steps of: plating a
conductive material onto the free end of the inter-connector; and
removing a portion of the conductive material to form the
conductive stub at the free end of the inter-connector.
19. The inter-connector formation method as in claim 1, the step of
depositing a structure material into the opening of the second
sacrificial layer to form the inter-connector comprising a step of:
depositing a structure material into the opening of the second
sacrificial layer using a deposition method selected from the group
consisting of laser deposition, ink-jet deposition and screen
printing.
20. The inter-connector formation method as in claim 2, the step of
depositing a structure material into the opening of the second
sacrificial layer comprising a step of: depositing a polymer-based
structure material into the opening of the second sacrificial
layer.
21. The inter-connector formation method as in claim 2, the step of
depositing a structure material into the opening of the second
sacrificial layer comprising a step of: depositing a composite
material into the opening of the second sacrificial layer.
22. The inter-connector formation method as in claim 2, the step of
depositing a structure material into the opening of the second
sacrificial layer comprising a step of: depositing a nano-material
into the opening of the second sacrificial layer
23. The inter-connector formation method as in claim 20, the step
of removing the first sacrificial material to expose the
inter-connector comprising a step of: removing the first
sacrificial material to expose a resiliently biased
inter-connector.
24. The inter-connector formation method as in claim 20, further
comprising a step of: coating the inter-connector with a conductive
material, the conductive material being in electrical communication
with the signal terminal.
25. The inter-connector formation method as in claim 24, the step
of coating the inter-connector with a conductive method comprising
a step of: coating the inter-connector using a coating method
selected from the group consisting of electroplating and
electroless-plating.
26. An inter-connector formation system for forming an
inter-connector for use as an electro-mechanical connector, the
inter-connector formation system comprising: means for forming a
first passage in a first sacrificial layer of a first sacrificial
material, the first sacrificial layer being formed over a portion
of a substrate, the first passage extending from a signal terminal
to an opening in the first sacrificial layer, and the signal
terminal being formed on the substrate; means for forming a
protrusion over the opening of the first sacrificial layer, the
protrusion being of a second sacrificial material and the second
sacrificial material further extending from the protrusion to the
signal terminal; means for forming a second passage in a second
sacrificial layer of the first sacrificial material, the second
sacrificial layer being formed over a portion of the second
sacrificial layer and the protrusion, the second passage extending
from the protrusion to an opening in the second sacrificial layer;
means for removing the second sacrificial material to expose a
structure channel extending from the signal terminal to the opening
in the second sacrificial layer, and the structure channel defining
the shape and dimension of the inter-connector; and means for
depositing a structure material into the opening of the second
sacrificial layer and thereby filling the structure channel
therewith, the structure material taking the shape and dimension of
the structure channel to form the inter-connector extending from
the signal terminal to the opening in the second sacrificial
layer.
27. The inter-connector formation system as in claim 26, further
comprising the means for removing the first sacrificial material to
expose the inter-connector.
28. An inter-connector formation method for forming an
inter-connector for use as an electro-mechanical connector, the
inter-connector formation method comprising the steps of: forming a
structure channel in a sacrificial layer of a sacrificial material,
the sacrificial layer being formed over a portion of a substrate,
the structure channel extending from a signal terminal to an
opening in the sacrificial layer, and the signal terminal being
formed on the substrate, and the structure channel defining the
shape and dimension of the inter-connector; and depositing a
structure material into the opening of the sacrificial layer and
thereby filling the structure channel therewith, the structure
material taking the shape and dimension of the structure channel to
form the inter-connector extending from the signal terminal to the
opening in the sacrificial layer, wherein the inter-connector
comprises of at least a first portion and a second portion and the
first portion of the inter-connector being perpendicular to the
second portion of the inter-connector.
29. The inter-connector formation method as in claim 26, further
comprising a step of removing the sacrificial material to expose
the inter-connector, the inter-connector having a cantilever
configuration and the inter-connector being resiliently biased and
electrically conductive.
Description
FIELD OF INVENTION
[0001] The present invention relates generally to an
inter-connector formation method. Specifically, the present
invention relates to an inter-connector formation technique for
forming an inter-connector for interconnecting two electronic
components.
BACKGROUND
[0002] Inter-connectors are typically used for interconnecting
electronic components, for example, devices on circuit boards or
circuits on integrated circuit chips. The inter-connectors may be
further used for interconnecting an integrated circuit chip and a
device.
[0003] Interconnections between electronic components are generally
classified into at least two broad categories of "relatively
permanent" and "readily demountable". An example of a "relatively
permanent" connector is, for example, a wire bond. The use of a
wire bond for interconnecting two electronic components requires a
contact element or "wire" element to be bonded on both the
electronic components. An "unbonding process" must be used to
separate the electronic components.
[0004] An example of a "readily demountable" connector is a rigid
contact structure of one electronic component for insertion into a
resilient socket of another electronic component. Another example
of a "readily demountable" connector is spring-like contact
structure of one electronic component for connecting to a terminal
of another electronic component.
[0005] The spring-like contact structure, also known as an
inter-connector, generally requires a certain amount of contact
force to effect reliable pressure contact to a terminal of an
electronic component. Therefore, the shape and metallurgy of the
inter-connector are important factors in determining the
effectiveness of the inter-connector for making pressure connection
to the terminal of the electronic component.
[0006] U.S. Pat. No. 6,268,015 by Mathieu describes a method for
making such an inter-connector. In Mathieu, lithographic and
planarisation methods were used to "make" the inter-connectors in
segments. The different segments of the inter-connector in Mathieu
were sequentially "stacked" by deposition of a conductive material
in a piece-meal manner. Therefore, the inter-connector in Mathieu
is formed from discontinued segments having joints therebetween.
Metallurgically, the joint stress due to joining a pair of
inter-connector segments and stress concentration at the joints due
forces applied to the inter-connector can lead to the mechanical
failure of the inter-connector in Mathieu.
[0007] Another disclosed invention describes the use of a cavity to
make an inter-connector formed from a single physically continuous
segment of conductive material. The cavity described therein is a
concavity having an opening. The cavity inwardly converges towards
the base of the cavity. The conductive material is deposited into
the opening for partially filling the cavity in a single step to
form the inter-connector. However, the dimension and
cross-sectional thickness formed using the disclosed method cannot
be accurately or consistently controlled.
[0008] Hence, this clearly affirms a need for an inter-connector
formation method for addressing the foregoing disadvantages of
conventional methods for making inter-connectors.
SUMMARY
[0009] In accordance with a first aspect of the invention, there is
disclosed an inter-connector formation method for forming a
wafer-level inter-connector for use as an electro-mechanical
inter-connector, the inter-connector formation method comprising
the steps of:
[0010] forming a first passage in a first sacrificial layer of a
first sacrificial material, the first sacrificial layer being
formed over a portion of a substrate, the first passage extending
from a signal terminal to an opening in the first sacrificial
layer, and the signal terminal being formed on the substrate;
[0011] forming a protrusion over the opening of the first
sacrificial layer, the protrusion being of a second sacrificial
material and the second sacrificial material further extending from
the protrusion to the signal terminal;
[0012] forming a second passage in a second sacrificial layer of
the first sacrificial material, the second sacrificial layer being
formed over a portion of the second sacrificial layer and the
protrusion, the second passage extending from the protrusion to an
opening in the second sacrificial layer;
[0013] removing the second sacrificial material to expose a
structure channel extending from the signal terminal to the opening
in the second sacrificial layer, and the structure channel defining
the shape and dimension of the inter-connector; and
[0014] depositing a structure material into the opening of the
second sacrificial layer and thereby filling the structure channel
therewith, the structure material taking the shape and dimension of
the structure channel to form the inter-connector extending from
the signal terminal to the opening in the second sacrificial
layer.
[0015] In accordance with a second aspect of the invention, there
is disclosed an inter-connector formation system for forming an
inter-connector for use as an electro-mechanical connector, the
inter-connector formation system comprising:
[0016] means for forming a first passage in a first sacrificial
layer of a first sacrificial material, the first sacrificial layer
being formed over a portion of a substrate, the first passage
extending from a signal terminal to an opening in the first
sacrificial layer, and the signal terminal being formed on the
substrate;
[0017] means for forming a protrusion over the opening of the first
sacrificial layer, the protrusion being of a second sacrificial
material and the second sacrificial material further extending from
the protrusion to the signal terminal;
[0018] means for forming a second passage in a second sacrificial
layer of the first sacrificial material, the second sacrificial
layer being formed over a portion of the second sacrificial layer
and the protrusion, the second passage extending from the
protrusion to an opening in the second sacrificial layer;
[0019] means for removing the second sacrificial material to expose
a structure channel extending from the signal terminal to the
opening in the second sacrificial layer, and the structure channel
defining the shape and dimension of the inter-connector; and
[0020] means for depositing a structure material into the opening
of the second sacrificial layer and thereby filling the structure
channel therewith, the structure material taking the shape and
dimension of the structure channel to form the inter-connector
extending from the signal terminal to the opening in the second
sacrificial layer.
[0021] In accordance with a third aspect of the invention, there is
disclosed an inter-connector formation method for forming an
inter-connector for use as an electro-mechanical connector, the
inter-connector formation method comprising the steps of:
[0022] forming a structure channel in a sacrificial layer of a
sacrificial material, the sacrificial layer being formed over a
portion of a substrate, the structure channel extending from a
signal terminal to an opening in the sacrificial layer, and the
signal terminal being formed on the substrate, and the structure
channel defining the shape and dimension of the inter-connector;
and
[0023] depositing a structure material into the opening of the
sacrificial layer and thereby filling the structure channel
therewith, the structure material taking the shape and dimension of
the structure channel to form the inter-connector extending from
the signal terminal to the opening in the sacrificial layer,
[0024] wherein the inter-connector comprises of at least a first
portion and a second portion and the first portion of the
inter-connector being perpendicular to the second portion of the
inter-connector.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Embodiments of the invention are described hereinafter with
reference to the following drawings, in which:
[0026] FIG. 1 shows a process flow diagram of an inter-connector
formation method according to a first embodiment of the
invention;
[0027] FIG. 2 shows a front view of an inter-connector formed by
the inter-connector formation method of FIG. 1;
[0028] FIG. 3 shows a process flow diagram of a step of forming a
structure channel in the inter-connector formation method of FIG.
1;
[0029] FIG. 4 shows a partial front sectional view of a substrate
with a first sacrificial layer formed in the step of forming a
structure channel in FIG. 3;
[0030] FIG. 5 shows a partial front sectional view of a substrate
with a first passage formed in the step of forming a structure
channel in FIG. 3;
[0031] FIG. 6 shows a partial front sectional view of a substrate
with a transitional layer formed in the step of forming a structure
channel in FIG. 3;
[0032] FIG. 7 shows a partial front sectional view of a substrate
with a protrusion formed in the step of forming a structure channel
in FIG. 3;
[0033] FIG. 8 shows a partial front sectional view of a substrate
with a second sacrificial layer formed in the step of forming a
structure channel in FIG. 3;
[0034] FIG. 9 shows a partial front sectional view of a substrate
with a second passage formed in the step of forming a structure
channel in FIG. 3;
[0035] FIG. 10 shows a partial front sectional view of a substrate
with a structure channel formed in the step of forming a structure
channel in FIG. 3;
[0036] FIG. 11 shows a partial front sectional view of a substrate
with a seed layer formed over the protrusion and the first
sacrificial layer of FIG. 7 in the step of forming a structure
channel in FIG. 3;
[0037] FIG. 12 shows a partial front sectional view of the
inter-connector of FIG. 2 with a conductive bump formed on the free
end thereof;
[0038] FIG. 13 shows a partial front sectional view of a substrate
with the structure channel of FIG. 10 being filled with a structure
material using a laser deposition device;
[0039] FIG. 14 shows a partial front sectional view of a substrate
with the structure channel of FIG. 10 being filled with a structure
material using an ink-jet deposition apparatus;
[0040] FIG. 15 shows a partial front sectional view of a substrate
with the structure channel of FIG. 10 being filled with a structure
material using a screen-printing assembly;
[0041] FIG. 16 shows a process flow diagram of an inter-connector
formation method of FIG. 1 according to a second embodiment of the
invention;
[0042] FIG. 17 shows a partial front sectional view of a substrate
with a structure channel formed in accordance with the second
embodiment of the inter-connector formation method of FIG. 16;
[0043] FIG. 18 shows a partial front sectional view of a substrate
with the structure channel of FIG. 17 being filled with a structure
material;
[0044] FIG. 19 shows a partial front sectional view of an
inter-connector formed with a structure material in accordance with
the second embodiment of the inter-connector formation method of
FIG. 16;
[0045] FIG. 20 shows a partial front sectional view of the
inter-connector of FIG. 19 with the structure material being plated
with a plating material; and
[0046] FIG. 21 shows a partial front sectional view of the
inter-connector of FIG. 21 with a conductive bump being formed on
the free-end thereof.
DETAILED DESCRIPTION
[0047] An object representation method for addressing the foregoing
problems is described hereinafter. The invention relates to an
inter-connector formation method for forming an inter-connector, by
lithographic techniques. The inter-connector is for use as an
electromechanical connector. The electromechanical connector is for
interconnecting electronic components, for example, a
semi-conductor device, a memory chip, a chip carrier or a portion
of a semi-conductor wafer.
[0048] A first embodiment of the invention, an inter-connector
formation method 300, as shown in FIG. 1, comprises of three main
steps: forming a structure channel, filling the structure channel
and freeing an inter-connector. The inter-connector formation
method 300 is for forming an inter-connector 60 having a
configuration as shown in FIG. 2.
[0049] With reference to FIG. 2, the inter-connector 60 extends
from a signal terminal 62 formed on a substrate 64. The substrate
64 is a panel on which integrated-circuits, printed circuits or the
like electronic circuits with contact elements are formed onto. The
signal terminals 62 are preferably one of copper (Cu), nickel (Ni)
or gold (Au) terminal pads for connecting to one of the contact
elements of the electronic circuits formed on the substrate 64.
[0050] The inter-connector 60 comprises of a post portion 66a, a
beam portion 66b and a tip portion 66c. The inter-connector 60
initially extends substantially perpendicular to a mounting face 68
of the substrate 64 to form the post portion 66a, then generally
parallel to the mounting face 68 of the substrate 64 to form the
beam portion 66b, and subsequently, substantially perpendicular to
the beam portion 66b to form the tip structure 66c.
[0051] The inter-connector 60 is resiliently biased and
electrically conductive for interconnecting an electrical component
and the substrate 64 and to enable electrical communication
therebetween.
[0052] The inter-connector 60 is formed over the substrate 64 using
the inter-connector formation method 300 by first forming the
structure channel in a step 310 of FIG. 1. FIG. 3 shows a process
flow diagram of the step 310 of FIG. 1. In the step 310, a first
sacrificial layer 70 is formed over the substrate 64 by depositing
a first sacrificial material 72 over the substrate 64, as shown in
FIG. 4, in a step 330. The first sacrificial layer 70 is patterned
and a portion of the first sacrificial layer 70 is removed in a
step 332 to form a first passage 74 as shown in FIG. 5. The first
passage 74 extends from the signal terminal 62 to an opening 76.
The first passage 74 is shaped and dimensioned according to the
shape and dimension of the post portion 66a of the inter-connector
60 of FIG. 2.
[0053] In a step 334 of FIG. 3, a second sacrificial material 78 is
spin-coated onto the first sacrificial layer 70, thereby filling
the first passage 74 and forming a transitional layer 78 over the
first sacrificial layer 70 as shown in FIG. 6. In a step 336, the
transitional layer 78 formed by the second sacrificial material 80
is patterned and a portion of the transitional layer 78 is removed
to expose a protrusion 82 extending from the first sacrificial
layer 70, as shown in FIG. 7, in a step 336. In the step 336, a
portion of the first sacrificial layer 70 is exposed when the
portion of the transitional layer 78 is removed. The protrusion 82
has the shape and dimension of the beam portion 66b of the
inter-connector 60.
[0054] As shown in FIG. 8, a second sacrificial layer 82 is then
formed in a step 338 by spin-coating the second sacrificial
material 80 over the first sacrificial layer 70 and the opening 76
of the first channel 74, with the second sacrificial material 80
filling the first channel 74. The second sacrificial layer 82 is
then patterned and a portion of the second sacrificial layer 82 is
removed in a step 340 to form a second passage 86 as shown in FIG.
9. The second passage 86 extends from the protrusion 82 to an
opening 88 and has the shape and dimension of the tip portion 66c
of the inter-connector 60.
[0055] The first sacrificial material 72 and the second sacrificial
material 80 are polymer based. Each of the first sacrificial
material 72 and the second sacrificial material 80 has a
degradation temperature. The degradation temperature is the
temperature at which the polymer-based material degrades. In the
inter-connector formation method 200, the degradation temperature
of the first sacrificial material 72 is higher than the degradation
temperature of the second sacrificial material 80. Preferably, the
degradation temperature of each of the first and second sacrificial
materials 72/80 is 400.degree. C. and 200.degree. C.
respectively.
[0056] In the step 310, the substrate 64 is heat-treated at a
temperature of generally 200.degree. C. in a step 342. At
200.degree. C., which is the degradation temperature of the second
sacrificial material 80, the second sacrificial material 80
degrades to expose the structure channel 90, as shown in FIG. 10,
and thereby completing the step 310.
[0057] In a step 312 of FIG. 1, a structure material 92 is
deposited into the structure channel 90 through the opening 88. The
structure material 92 is deposited using a suitable deposition
technique chemical vapour deposition (CVD), sputter deposition, and
electroless plating. The structure material 92 is electrically
conductive and is preferably one of copper, nickel alloy or the
like electrically conductive material.
[0058] When electroplating is employed as the deposition technique,
in the step 312, a seed layer 94 has to be formed below the first
passage 74 is formed in the step 332. The seed layer 94, as shown
in FIG. 11, is formed below the first sacrificial layer 70 with the
seed layer 94 extending over the signal terminal 62.
[0059] Electroplating requires the structure material 92, for
example nickel, copper, cobalt, palladium, nickel cobalt or the
like electroplating structure material, to be applied in a form of
a commercially available bath or solution. Therefore in the step
312, a current is applied between an anode (not shown) on the
signal terminal 62, thereby creating negative charge build-up on
the signal terminal 62. The negative charge build-up causes metal
ions from the electroplating solution to be reduced to its metallic
state and hence, depositing the nickel cobalt structure material
onto the signal terminal 62 and filling the structure channel 90 in
the process.
[0060] The structure material 92 deposited in the step 312, extends
from the signal terminal 62 to the opening 88 of the second
sacrificial material 80.
[0061] In a step 314 of FIG. 1, the inter-connector 60 is freed
from the first sacrificial material 72 by heat-treating the first
sacrificial material 72 at a temperature of generally 400.degree.
C. At 400.degree. C., which is the degradation temperature of the
first sacrificial material 72, the first sacrificial material
degrades to expose the inter-connector as shown in FIG. 2.
[0062] Further in the step 312, a bump 96 can be one of
electroplated or deposited onto a free end 98 of the
inter-connector 60. The bump 96 is electrically conductive.
Following the formation of the bump 96, the step 314 exposes the
inter-connector 60 as shown in FIG. 12.
[0063] In the step 312, various methods can be employed for
depositing the structure material 92 into the structure channel 90.
A laser processing technique, as shown in FIG. 13, can be employed
in the step 312 for depositing the structure material 92, a high
temperature solder, into the structure channel 90. The laser
processing technique is typically employed in a vacuum using a
laser-based device 104.
[0064] Alternatively, an ink-jet deposition apparatus 106, as shown
in FIG. 14, can be used for depositing the structure material 92
into the structure channel 90. Besides using the ink-deposition
apparatus, a screen-printing technique can be employed in the step
312. The screen-printing technique uses a screen-printing apparatus
110 for directing and thereby depositing the structure material 92
into the structure channel 90 as shown in FIG. 15.
[0065] A second embodiment of the invention, an inter-connector
formation method 350 as shown in FIG. 16, comprises of four main
steps for forming an inter-connector 200: forming a structure
channel, filling the structure channel, releasing an
inter-connector and plating the inter-connector. The description in
relation to steps 310, 312 and 314 described in the first
embodiment of the invention with reference to FIG. 1 are
incorporated herein as steps 360, 362 and 364 respectively.
[0066] In the step 360, a structure channel 120 is formed in a
first sacrificial layer 122 and a second sacrificial layer 124 as
shown in FIG. 17. Both the first sacrificial layer 122 and the
second sacrificial layer 124 are formed from a first sacrificial
material 126. The structure channel 120 extends from a signal
terminal 128 to an opening 130, with the signal terminal 128 being
formed on a substrate 132.
[0067] Following the step 360, the structure channel 120 is filled
with a structure material 134 in a step 362 as shown in FIG. 18.
Each of the structure material 134 and the first sacrificial
material 126 has a degradation temperature with the degradation
temperature of the structure material 134 being higher than the
degradation temperature of the first sacrificial material 126.
[0068] In the step 364 of FIG. 16, the inter-connector 200 is freed
from the first sacrificial material 126 by heat-treating the first
sacrificial layer 124 and the second sacrificial layer 126 at the
degradation temperature of the first sacrificial material 126. The
first sacrificial material 126 degrades after heat treatment to
free the structure material 134 and therefore the inter-connector
200 as shown in FIG. 19.
[0069] The structure material 134 is preferably polymer-based and
having polymeric and structural properties to impart biased
resiliency to the inter-connector 200. Alternatively, one of a
composite material or a nano-material is used as the structure
material 134. The nano-material, for example nano-copper, is used
for its enhanced mechanical properties.
[0070] Following the step 364, the inter-connector 200 is
electroplated with a plating material 136 in a step 366 as shown in
FIG. 20. The plating material 136 plated onto the inter-connector
200 is electrically conductive and in electrical communication with
the signal terminal 128.
[0071] Further in the step 366, a bump 138 can be one of
electroplated or deposited onto a free end 140 of the
inter-connector 200. The bump 140 is electrically conductive. In
the second embodiment of the inter-connector formation method 350,
the inter-connector 200 formed from both the structure material 134
and the plating material 136. This enables both the structure
material 134 and the plating material 136 to perform decoupled
functions with the structure material 134 providing the structural
support and biased resiliency and the plating material 136
providing electrical conductivity. By using the polymer-based
structure material 134, the need and dependency on metals for
producing inter-connectors 200 are substantially reduced.
[0072] In the foregoing manner, an inter-connector formation method
for forming an inter-connector for use as an electromechanical
inter-connector is described according to two embodiments of the
invention for addressing the foregoing disadvantages of
conventional methods for forming inter-connectors. Although only
two embodiments of the invention is disclosed, it will be apparent
to one skilled in the art in view of this disclosure that numerous
changes and/or modification can be made without departing from the
scope and spirit of the invention.
* * * * *