U.S. patent application number 11/805300 was filed with the patent office on 2008-06-12 for structure and method of making interconnect element having metal traces embedded in surface of dielectric.
This patent application is currently assigned to Tessera Interconnect Materials, Inc.. Invention is credited to Yukio Hashimoto, Kiyoshi Hyodo, Tomoo Iijima, Hideki Kotake, Inetaro Kurosawa, Toku Yoshino.
Application Number | 20080136041 11/805300 |
Document ID | / |
Family ID | 46328768 |
Filed Date | 2008-06-12 |
United States Patent
Application |
20080136041 |
Kind Code |
A1 |
Kotake; Hideki ; et
al. |
June 12, 2008 |
Structure and method of making interconnect element having metal
traces embedded in surface of dielectric
Abstract
An interconnect element is provided which includes a dielectric
element having a major surface. Metal interconnect patterns are
embedded in recesses which extend inwardly from the major surface,
the outer surfaces of the interconnect patterns being substantially
co-planar with the major surface and extending in one or more
directions of the major surface. A projecting conductive film
extends over the major surface in at least one direction parallel
to a plane defined by the major surface such that it contacts the
dielectric element along at least a portion of the major surface
and conductively contacts an outer surface of at least one of the
metal interconnect patterns.
Inventors: |
Kotake; Hideki; (Tokyo,
JP) ; Hyodo; Kiyoshi; (Tokyo, JP) ; Kurosawa;
Inetaro; (Tokyo, JP) ; Hashimoto; Yukio;
(Tokyo, JP) ; Yoshino; Toku; (Tokyo, JP) ;
Iijima; Tomoo; (Tokyo, JP) |
Correspondence
Address: |
TESSERA;LERNER DAVID et al.
600 SOUTH AVENUE WEST
WESTFIELD
NJ
07090
US
|
Assignee: |
Tessera Interconnect Materials,
Inc.
San Jose
CA
|
Family ID: |
46328768 |
Appl. No.: |
11/805300 |
Filed: |
May 23, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11541734 |
Oct 2, 2006 |
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11805300 |
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11338455 |
Jan 24, 2006 |
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11541734 |
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Current U.S.
Class: |
257/774 ;
257/E21.495; 257/E23.01; 438/618 |
Current CPC
Class: |
H05K 3/4617 20130101;
H01L 2924/181 20130101; H05K 3/4038 20130101; H05K 3/428 20130101;
H01L 2224/73265 20130101; H05K 2201/0379 20130101; H05K 2201/096
20130101; H05K 3/20 20130101; H05K 3/429 20130101; H01L 2924/181
20130101; H05K 3/4658 20130101; H01L 2924/00014 20130101; H01L
2924/00012 20130101; H05K 2201/09536 20130101; H05K 2203/0733
20130101; H05K 3/4611 20130101; H05K 3/4614 20130101; H05K 3/4647
20130101; H05K 3/4602 20130101; H05K 3/462 20130101; H05K 3/06
20130101; H05K 2201/10378 20130101; H05K 2203/0376 20130101; H01L
2224/48091 20130101; H01L 2224/48091 20130101; H05K 2203/0384
20130101; H05K 2203/1536 20130101 |
Class at
Publication: |
257/774 ;
438/618; 257/E23.01; 257/E21.495 |
International
Class: |
H01L 23/48 20060101
H01L023/48; H01L 21/4763 20060101 H01L021/4763 |
Claims
1. An interconnect element, comprising: a dielectric element having
a major surface and a plurality of recesses extending inwardly from
said major surface; a plurality of metal interconnect patterns
embedded in said plurality of recesses, said plurality of metal
interconnect patterns having outer surfaces substantially co-planar
with said major surface and extending in one or more directions of
said major surface; and a projecting conductive film extending over
said major surface in at least one direction parallel to a plane
defined by said major surface to contact said dielectric element
along at least a portion of said major surface and conductively
contact an outer surface of at least one of said metal interconnect
patterns.
2. The interconnect element as claimed in claim 1, further
comprising an insulating cover film overlying only a portion of
said major surface and at least one of said metal interconnect
patterns such that said projecting conductive film is exposed by
said insulating cover film.
3. The interconnect element as claimed in claim 1, wherein at least
a portion of said projecting conductive film conductively
interconnects respective ones of said metal interconnect
patterns.
4. The interconnect element as claimed in claim 1, wherein said
major surface is a first major surface, said dielectric element
includes a second major surface remote from said first major
surface and a plurality of second recesses extending inwardly from
said second major surface, said metal interconnect patterns are
first metal interconnect patterns embedded in said first recesses,
and said interconnect element further comprises a plurality of
second metal interconnect patterns embedded in said second recesses
extending in one or more directions of said second major surface
and having outer surfaces substantially co-planar with said second
major surface, and at least some of said first metal interconnect
patterns are conductively connected to at least some of said second
metal interconnect patterns.
5. The interconnect element as claimed in claim 4, wherein said at
least some first metal interconnect patterns are conductively
connected to said at least some second metal interconnect patterns
by one or more conductors extending through said dielectric element
in a direction transverse to said plane defined by said first major
surface of said dielectric element.
6. The interconnect element as claimed in claim 5, wherein said one
or more conductors extending through said dielectric element
includes a conductor lining a through hole extending through said
dielectric element.
7. An assembly including the interconnect element as claimed in
claim 6, further comprising an external circuit element having an
exposed lead inserted into said through hole in conductive contact
with said conductor to provide conductive interconnection to said
interconnect element.
8. The interconnect element as claimed in claim 5, wherein said one
or more conductors extending through said dielectric element
includes a solid conductive post contacting inner surfaces of at
least some of said first and second metal interconnect patterns
recessed inwardly from said first and second major surfaces.
9. The interconnect element as claimed in claim 4, further
comprising a first insulating cover film overlying a first portion
of said first major surface and at least one of said first metal
interconnect patterns such that said projecting conductive film is
exposed by said insulating cover film.
10. An assembly including the interconnect element as claimed in
claim 1, further comprising an external circuit element including
an exposed contact, said contact being conductively connected to
said projecting conductive film.
11. The assembly as claimed in claim 10, wherein said projecting
conductive film is conductively connected to said contact through
an anisotropic conductive film.
12. A method of fabricating an interconnect element, comprising:
providing structure including a first metal layer overlying a
second metal layer; patterning a plurality of metal interconnect
patterns from said first metal layer; forming a dielectric element
overlying said structure; removing said second metal layer
selectively to said plurality of metal interconnect patterns, such
that said plurality of metal interconnect patterns are embedded in
said dielectric element, said metal interconnect patterns having
outer surfaces co-planar with a first major surface of said
dielectric element; and forming a projecting conductive film
extending over said first major surface in at least one direction
parallel to a plane defined by said major surface to contact said
dielectric element along at least a portion of said first major
surface and conductively contact an outer surface of at least one
of said metal interconnect patterns.
13. The method as claimed in claim 12, wherein said step of forming
said dielectric element includes pressing a layer including an
uncured resin over said plurality of metal interconnect
patterns.
14. The method as claimed in claim 12, wherein said metal
interconnect patterns are first metal interconnect patterns
embedded in first recesses extending inwardly from said first major
surface, said method further comprising providing a second
structure including a third metal layer overlying a fourth metal
layer and patterning a plurality of second metal interconnect
patterns from said third metal layer, said step of forming said
dielectric element including pressing said second structure onto a
second major surface of said dielectric element remote from said
first major surface and removing said fourth metal layer
selectively to said plurality of second metal interconnect
patterns, such that said second metal interconnect patterns are
embedded in said second major surface of said dielectric element
and said second metal interconnect patterns have outer surfaces
co-planar with said second major surface, said method further
comprising: forming a through hole extending through said
dielectric element between said first metal interconnect patterns
and said second metal interconnect patterns; and forming a
conductor lining said through hole to connect said first metal
interconnect patterns to said second metal interconnect patterns
simultaneously when forming said projecting conductive film.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 11/541,734, filed Oct. 2, 2006, which is a continuation of U.S.
application Ser. No. 11/338,455, filed Jan. 24, 2006, the
disclosures of which is hereby incorporated herein by reference.
The present application is based upon and claims the benefit of
priority from Japanese Patent Application No. 2005-15970, filed
Jan. 24, 2005, the disclosure of which is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] The present invention specifically relates to interconnect
structures for microelectronics, e.g., in the packaging of
microelectronic units such as integrated circuits ("ICS" or
"chips") and other interconnect structures, e.g., circuit panels
such as includes printed or other types of wiring boards.
[0003] There is a present need to provide interconnect elements
having either a single layer or multiple layers of metal
interconnect patterns permitting selective interconnection to
external circuit elements.
SUMMARY OF THE INVENTION
[0004] In accordance with an aspect of the invention, an
interconnect element includes a dielectric element having a major
surface. Metal interconnect patterns extending in one or more
directions of the major surface are embedded in recesses which
extend inwardly from the major surface. Outer surfaces of the
interconnect patterns are substantially co-planar with the major
surface. A projecting conductive film extends over the major
surface in at least one direction parallel to a plane defined by
the major surface. The projecting conductive film contacts the
dielectric element along at least a portion of the major surface
and conductively contacts an outer surface of at least one of the
metal interconnect patterns.
[0005] In accordance with one or more preferred aspects of the
invention, the interconnect element may further include an
insulating cover film overlying only a portion of the major surface
and at least one of the metal interconnect patterns such that the
projecting conductive film is exposed by the insulating cover
film.
[0006] In accordance with one or more preferred aspects of the
invention, at least a portion of the projecting conductive film
conductively interconnects respective ones of the metal
interconnect patterns.
[0007] In accordance with a preferred embodiment of the invention,
the major surface is a first major surface, the dielectric element
includes a second major surface remote from the first major surface
and a plurality of second recesses extend inwardly from the second
major surface. In such embodiment, the metal interconnect patterns
are first metal interconnect patterns embedded in the first
recesses, and the interconnect element further includes a plurality
of second metal interconnect patterns which extend in one or more
directions of the second major surface. These second metal
interconnect patterns are embedded in the second recesses, and have
outer surfaces that are substantially co-planar with the second
major surface. In addition, at least some of the first metal
interconnect patterns are conductively connected to at least some
of the second metal interconnect patterns.
[0008] In accordance with one or more preferred aspects of the
invention, at least some of the first metal interconnect patterns
are conductively connected to at least some of the second metal
interconnect patterns. Connection is provided by one or more
conductors which extend through the dielectric element in a
direction transverse to the plane defined by the first major
surface of the dielectric element.
[0009] Preferably, the one or more conductors extending through the
dielectric element includes a conductor lining a through hole
extending through the dielectric element.
[0010] In a particular aspect of the invention, an assembly
includes an interconnect element as specified herein and further
includes an external circuit element. An exposed lead of such
circuit element is inserted into the through hole in conductive
contact with the conductor to provide conductive interconnection to
the interconnect element.
[0011] In accordance with another preferred aspect of the
invention, a solid conductive post extends through the dielectric
element which contacts inner surfaces of at least some of the first
and second metal interconnect patterns, these inner surfaces being
recessed inwardly from the first and second major surfaces of the
dielectric element.
[0012] In accordance with another preferred aspect of the
invention, a first insulating cover film overlies a first portion
of the first major surface and at least one of the first metal
interconnect patterns, such that the projecting conductive film is
exposed by the insulating cover film.
[0013] An assembly in accordance with a particular aspect of the
invention includes an interconnect element as specified herein and
an external circuit element. An exposed contact of the external
circuit element is conductively connected to the projecting
conductive film of the interconnect element.
[0014] Preferably, the projecting conductive film is conductively
connected to the contact through an anisotropic conductive
film.
[0015] In accordance with another aspect of the invention, a method
is provided for fabricating an interconnect element. In accordance
with such method, a structure is provided which includes a first
metal layer overlying a second metal layer. A plurality of metal
interconnect patterns are patterned from the first metal layer of
the structure after which a dielectric element is formed overlying
the metal interconnect patterns of the structure. The second metal
layer is then removed selectively to the plurality of metal
interconnect patterns, such that the plurality of metal
interconnect patterns are embedded in the dielectric element and
have outer surfaces co-planar with a first major surface of the
dielectric element. A projecting conductive film is formed to
extend over the first major surface in at least one direction
parallel to a plane defined by the major surface so as to contact
the dielectric element along at least a portion of the first major
surface and conductively contact an outer surface of at least one
of the metal interconnect patterns.
[0016] Preferably, the step of forming the dielectric element
includes pressing a layer including an uncured resin over the
plurality of metal interconnect patterns.
[0017] In accordance with a particular aspect of the invention, the
metal interconnect patterns are first metal interconnect patterns
embedded in first recesses extending inwardly from the first major
surface. Preferably, the method further includes providing a second
structure including a third metal layer overlying a fourth metal
layer and patterning a plurality of second metal interconnect
patterns from the third metal layer. The step of forming the
dielectric element additionally includes pressing the second
structure onto a second major surface of the dielectric element
remote from the first major surface. The fourth metal layer is then
removed selectively to the plurality of second metal interconnect
patterns. In this way, the second metal interconnect patterns are
embedded in the second major surface of the dielectric element and
the second metal interconnect patterns have outer surfaces
co-planar with the second major surface. Further in accordance with
such aspect of the invention, a through hole is formed to extend
through the dielectric element between the first metal interconnect
patterns and the second metal interconnect patterns, and a
conductor is formed to line the through hole simultaneously when
forming the projecting conductive film, such conductor connecting
the first metal interconnect patterns to the second metal
interconnect patterns.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIGS. 1(A) through (K) are cross sectional diagrams of
series of processes (A) through (K) according to a first embodiment
of the present invention.
[0019] FIGS. 2 (L) through (M) are cross sectional diagrams of a
series of processes (L) through (M) according to the first
embodiment of the present invention.
[0020] FIGS. 3 (A) through (H) are cross sectional diagrams
illustrating a process according to a second embodiment of the
present invention.
[0021] FIGS. 4 (I) through (M) are cross sectional diagrams further
illustrating a process according to the second embodiment of the
present invention.
[0022] FIGS. 5 (H) through (K) are cross-sectional diagrams
illustrating a process according to a variation of the second
embodiment of the present invention.
[0023] FIGS. 6 (A) through (D) are cross-sectional diagrams
illustrating a series of processes in a third embodiment according
to the present invention.
[0024] FIGS. 7 (A) through (H) are cross-sectional diagrams
illustrating a series of processes in a method for manufacturing an
interconnect element for an outermost layer according to a fourth
embodiment of the present invention.
[0025] FIGS. 8 (A) through (H) are cross-sectional diagrams showing
the series of processes for processing a core wiring board, for
integrating interconnect elements for outermost layers with this
core wiring board, and for finishing a wiring board through
processing the interconnect elements for outermost layers,
according to such fourth embodiment.
[0026] FIGS. 9 (A) through (I) are cross-sectional diagrams showing
a series of processes in a fifth embodiment according to the
present invention.
[0027] FIGS. 10 (A) through (H) are cross-sectional diagrams
showing a series of processes in a sixth embodiment according to
the present invention.
[0028] FIGS. 11(A) through (F) and FIGS. 12(G) through 12(I) are
cross-sectional diagrams showing a series of processes in
accordance with a seventh embodiment of the present invention.
[0029] FIG. 13 is a cross-sectional diagram illustrating an
interconnect element and its interconnection with an external
circuit element in accordance with a variation of the seventh
embodiment illustrated in FIG. 12(I).
[0030] FIGS. 14(A) and 14(B) are cross-sectional diagrams
illustrating an interconnect element and its interconnection with
an external circuit element in accordance with a further variation
of the seventh embodiment illustrated in FIG. 12(I).
DETAILED DESCRIPTION
[0031] According to certain embodiments of the invention, a
multilayer interconnect element or multilayer wiring board is
provided wherein metal traces of an interconnection layer are
embedded within recesses at the surface of a dielectric element. In
addition, the metal traces are formed in such manner that they are
much less prone to become twisted, or produce shorts with adjacent
interconnections, or break, even when the number of interconnect
elements joined together is high. In such embodiments, the surface
of each interconnect element presents a substantially planar major
surface having conductive contacts thereon for interconnection with
other microelectronic elements. In this way, the metal traces do
not protrude in ways which interfere with mounting electronic
components. Also, improved reliability of the electrical
connections may be achieved between several interconnect elements
that make up a multilayer interconnect element or multilayer wiring
board having three or more layers on which such embedded metal
traces are provided. In addition, it may be possible to achieve a
reduction in the manufacturing processes required to fabricate such
interconnect elements.
[0032] In an interconnect element 22 according to an embodiment of
the present invention shown in FIG. 2(M), a dielectric element 20,
preferably includes one or more thermoplastic resins or consists
essentially of one or more thermoplastic resins, where, for
example, PEEK (polyether ether ketone) resin, PES resin, PPS
(polyphenylene sulfide) resin, PEN (polyethylene napthalate) resin,
a PEEK-PES resin polymer blend, and liquid crystal polymers are
specific examples of preferred resins. The thickness of the
dielectric element is preferably between several dozen and several
hundred microns.
[0033] Embedded within the dielectric element 20 are first
interconnection patterns 12, 12a provided as a first metal wiring
layer and second interconnection patterns 13, 13a provided by a
second metal wiring layer. Each of the first interconnect patterns
and the second interconnect patterns includes a plurality of metal
traces and contacts or other metallic interconnect features. The
thickness of each metal wiring layer is preferably between about 10
microns and several dozen microns. The contacts and metal traces
function to provide conductive interconnection between the
interconnect element 22 and other microelectronic elements external
thereto and/or between different external microelectronic elements.
Such microelectronic elements can be, for example, any of
microelectronic substrates, circuit panels, integrated circuits
("ICs" or "chips"), packaged chips, i.e., chips having package
elements bonded thereto, whether or not such chips include only
active circuit elements, passive circuit elements such as commonly
known as "integrated passives on chip" (IPOC) or chips having a
combination of active and passive types of circuit elements, among
others.
[0034] A plurality of solid metal posts 18 extend through the
dielectric element 20 between the first interconnect patterns 12
and the second interconnect patterns 13. The posts most preferably
include or consist essentially of copper. Preferably the posts
include high purity copper. The end-to-end length or "height" of
each post within the dielectric element 20 is preferably between,
for example, several dozen and about 150 microns. However, the
height may be somewhat greater than or less than the stated
preferred range.
[0035] In a particular embodiment a chip, circuit panel or packaged
chip is directly or indirectly conductively interconnected to or
bonded to interconnection patterns 12, 12a including traces and
contacts exposed at a first major surface 24 of the interconnect
element 22. On a second major surface 26 of the interconnect
element 22 remote from the first major surface 24, contacts 13, 13a
of the interconnect element can be further bonded, directly or
indirectly, to a circuit panel, another chip, or package element of
another packaged chip. In another embodiment, the metal traces on
one or both major surfaces 24, 26 of the interconnect element 22
can be contacted by a packaged chip and maintain conductive
communication with the packaged chip under a moderate amount of
pressure in which some flexing of the dielectric element 20 may
occur as a result of the pressure between the interconnect element
and the packaged chip.
[0036] In an embodiment of manufacturing a multilayer interconnect
element or wiring board, heating to a temperature of, for example,
between 150 and 350.degree. C. is suitable, and a pressure between
20 and 100 kg/cm.sup.2 is preferred. In addition, it is preferable
to coat the metal traces exposed at one or both of the first and
second major surfaces 24, 26 with a bond metal, especially when
electronic components are to be mounted thereto such as integrated
circuits (ICs or chips) that have high numbers of terminals with
minute pitches. Gold is well suited for use as the bond metal layer
10.
[0037] The details of the present invention will be explained based
on an embodiment shown in a figure. FIGS. 1(A) through (K) and
FIGS. 2(L) through (M) are cross-sectional diagrams showing the
sequence of processes (A) through (M) in a first embodiment
according to the present invention.
[0038] First, a patternable conductive structure 2, made from a
three metal layer structure is prepared as shown in FIG. 1(A). The
patternable conductive structure 2 has a three-layer structure
wherein, for example, an etching barrier layer (an intermediate
layer) 6 including or consisting essentially of a metal such as
nickel, for example, is fabricated on the surface of a carrier
layer 4 made from, for example, copper, and a metal layer 8 for
fabricating an interconnection layer made from, for example,
copper, is fabricated on the surface of this etching barrier layer
6.
[0039] Following this, as shown in FIG. 1(B), a protective layer
10, made from, for example, photoresist, is provided on the surface
of the aforementioned carrier layer 4. Layer 10 protects the
carrier layer 4 when the metal layer 8 is patterned, e.g., by
photolithography and selective etching to form the interconnection
patterns 12. Note that 12a indicates the interconnection patterns
which are not conductively metal posts or other electrically
conductive pillars extending therefrom.
[0040] Following this, as shown in FIG. 1(C), a photoresist layer
14 is fabricated on the surface on which the aforementioned
interconnection patterns 12, 12a are fabricated.
[0041] Following this, as shown in FIG. 1(D), an exposure process
is performed on the aforementioned photoresist layer 14. Following
exposure, 14a is the exposed portion, and 14b is the non-exposed
portion.
[0042] Following this, as shown in FIG. 1(E), a developing process
is performed. 16 is a hole that is produced by the developing
process.
[0043] Following this, as shown in FIG. 1(F), preferably, an
after-exposure process is performed. Preferably, the exposure dose
in this process is larger than the previous exposure dose with
respect to FIG. 1(E). The exposed photoresist is then removed, as
by a soft etching process, after which ultrasonic rinsing is
preferably performed.
[0044] Following this, as shown in FIG. 1(G), the aforementioned
patterned resist layer 14a is used as a mask to fabricate metal
posts 18 or other electrically conductive pillars as vertically
rising features that extend upward from the interconnection
patterns 12 within the aforementioned holes 16. Preferably, the
posts include or consist essentially of one or more metals, for
example, copper, preferably formed by plating. This process is
performed so that the electrically conductive pillars 18 preferably
have a length or height that extends beyond the major surface 23 of
the aforementioned resist layer 14a and ends or tops 19 of the
pillars 18 protrude above the resist layer 14a.
[0045] Following this, referring to FIG. 1(H), a grinding or
polishing process is performed until the ends or tops 19a of the
aforementioned electrically conductive pillars 18 are co-planar
(i.e., are positioned on the same plane as) with the surface of the
resist layer 14a. In such way, after processing the tops 19a
present flat surfaces.
[0046] Following this, as shown in FIG. 1(I) the aforementioned
photoresist layer 14a is removed through stripping, or the like
and, at the same time, the aforementioned protective layer 10 is
also removed from the surface of the carrier layer 4.
[0047] Following this, as shown in FIG. 1(J) a dielectric element,
an interlayer insulation layer 20 preferably made from a resin is
formed through a method such as pressure adhesion, on the surface
whereon the aforementioned electrically conductive pillars 18 are
formed. In one embodiment, the interlayer insulation layer includes
an uncured resin, such layer being provided in form of an epoxy
prepreg, for example. Thereafter, the aforementioned interlayer
insulation layer 20 is polished or ground until the end surfaces of
the aforementioned electrically conductive pillars 18 are exposed.
FIG. 1(J) illustrates a planarized condition of the interlayer
insulation layer 20 and the posts 18 in a partly formed first
interconnect structure 2' after the grinding process.
[0048] Following this, the first such interconnect structure 2',
having an insulating layer 20 is formed in the state shown in FIG.
1(J). In addition, a patternable conductive structure 2 is provided
which has exposed interconnect patterns 12, as shown in FIG. 1(B).
The two structures 2 and 2' are then aligned together so that the
end surfaces 19a of the metal posts or electrically conductive
pillars 18 contact the interconnect patterns 12 of structure 2.
Pressure and heat are then applied to join and bond the metal posts
18 to the interconnect patterns of the opposing conductive
structure 2. FIG. 1(K) shows the state after this integration.
[0049] This joining process connects the metal posts 18 to the
interconnect patterns, doing so through metal-to-metal bonding of
the posts 18 to the interconnect patterns 13 and 13, especially via
copper-to-copper contact. This process integrates the two
structures 2 and 2' into a single unit.
[0050] Following this, as shown in FIG. 2(L), the respective
carrier layers 4 and 4 (FIG. 1(A)) are removed through, for
example, etching.
[0051] Following this, as shown in FIG. 2(M), the aforementioned
etching barrier layers 6 and 6, made from nickel, are removed
through, for example, etching.
[0052] Given this type of method for manufacturing, an interconnect
element or wiring board is fabricated wherein the interconnection
layer and the insulating layer are co-planar as shown in FIG. 2(M),
fabricated such that outer surfaces 21 of the interconnect patterns
12 and 12a are co-planar with the first major surface 24 and the
outer surfaces 21a of the interconnect patterns 13, 13a are
co-planar with the second major surface 26.
[0053] FIGS. 3(A) through (H) and FIGS. 4 (I) through (M) are
cross-sectional diagrams showing a series of processes (A) through
(M) in a second embodiment according to the present invention.
[0054] As shown in FIG. 3(A), two patternable conductive structures
32 and 32, and a core 30, are prepared, the core being made from,
for example, a resin. An adhesive sheet 34, made from, for example,
a prepreg, or the like, is formed on a part of both sides of this
core 30, the prepreg being made from, for example, an epoxy resin.
The core 30 will be removed later as being an unneeded area.
[0055] Note that each of the aforementioned patternable conductive
structures 32 have three-layer structures wherein a metal layer 40
for fabricating an interconnection layer including or consisting
essentially of copper, for example, overlies an etching barrier
layer (an intermediate layer) 34, which includes or consists
essentially of a metal that would not be attacked by an etchant
which attacks the first metal. For example, when the first metal
includes or consists essentially of copper, and the etching barrier
layer can include or consist essentially of nickel. Copper can be
etched by an etchant which substantially does not attack nickel. In
turn, the first metal 40 and the etching barrier layer 34 are
provided on or overlying a surface of a carrier layer 36 made from,
for example, copper. The patternable conductive structure is
preferably fabricated through rolling, although other methods can
be used.
[0056] Following this, as shown in FIG. 3(B), the patternable
conductive structures 32 and 32 are adhered, through the
aforementioned adhesive sheet 34, to both surfaces of the core
material 30, such that the metal layer 36 which is the carrier
faces the surface of said core material 30. This adhesive sheet 34
is disposed at one or more locations of the patternable conductive
structures away from locations where interconnect patterns are to
be formed (the active region). Thus, the adhesive sheet 34 is
disposed preferably only in an unneeded region.
[0057] Following this, as shown in FIG. 3(C), interconnection
layers 42 are formed through selectively etching the metal layers
40 of each of the aforementioned patternable conductive structures
32 and 32.
[0058] Following this, as is shown in FIG. 3(D), photoresist layers
44 are deposited over surfaces 43 of both of the interconnection
layers 42. These resist layers 44 are formed with a thickness that
is essentially at the same height as the end surface of the
electrically conductive pillars 48 (FIG. 1(F)) to be formed, or
with a surface that is slightly lower.
[0059] Following this, as is shown in FIG. 3(E), each of the
aforementioned resist layers 44 are patterned, such as by
photolithography, to form the holes 46.
[0060] Following this, as is shown in FIG. 3(F), metal posts 48 or
other electrically conductive pillars 48 are fabricated within the
holes of the resist layer 44. Preferably, the posts are fabricated
by plating with a metal such as copper, for example, using the
aforementioned resist layers 44 as masks. The fabrication of these
electrically conductive pillars 48 may be performed through
overplating, as appropriate, to an extent that the metal posts 48
extend beyond the major surfaces 45 of the interlayer insulation
layers 44 such as in the above-described embodiment shown in FIGS.
1(A)-1(K) and FIGS. 2(L)-2(M). Thereafter, grinding or polishing is
performed to cause the outer surfaces of the electrically
conductive pillars 48 to be co-planar with the major surfaces 45 of
the interlayer insulation layer 44.
[0061] Following this, as shown in FIG. 3(G), each of the
aforementioned resist layers 44 is removed.
[0062] Following this, as shown in FIG. 3(H), interlayer insulation
layers 50 are formed on each of the surfaces whereon the
interconnection layers 42 and the electrically conductive pillars
48 are fabricated. These insulation layers are formed, for example,
by a pressure adhesion method, after which the end surfaces of the
aforementioned electrically conductive pillars 48 are exposed
through grinding the aforementioned interlayer insulation layers
50.
[0063] Following this, as shown in FIG. 4(I), interconnect
structures 52 and 52 are aligned and overlaid over each of the
aforementioned interlayer insulation layers 50 and 50.
[0064] Each of the aforementioned interconnection structures 52 and
52 includes an interconnection layer including interconnection
patterns 60. The interconnection layer may include or consist
essentially of copper, for example. In turn, the interconnection
layer overlies an etching barrier layer (an intermediate layer 56),
made from, for example, nickel. The etching barrier layer, in turn,
overlies a carrier layer 54, made from, for example, copper.
Moreover, each of these interconnection structures 52 and 52 are
oriented so that the sides whereon the interconnect patterns 60 are
formed are facing each of the interlayer insulation layers 50 and
50, and are provided aligned so that the various electrically
conductive pillars 48 will be lined up with the corresponding
interconnection layers 60.
[0065] Following this, as shown in FIG. 4(J), the interconnect
structures 52 and 52 are aligned and joined with the aforementioned
interlayer insulation layers 50 and 50 through the application of
heat and pressure. Consequently, the various electrically
conductive pillars 48 integrated, through metal-to-metal bonding,
for example, copper-copper bonding, with the corresponding
interconnection layers 60. In addition, the interlayer insulation
layer 50 becomes joined to the structure 52.
[0066] Following this, as shown in FIG. 4(K), that which was
integrated in FIG. 4(J) is cut at the part wherein the
aforementioned adhesive 34 is adhered, to separate the unneeded
core 30 from the active region, the active region being the two
interconnect elements 55 each having a first interconnection layer
42 and a second interconnection layer 60 on a side of the
interconnect element 55 remote from the first interconnection layer
42.
[0067] Following this, the aforementioned carrier layers 54 (FIG.
4(I)) and 36 (FIG. 4(I)) are removed from the interconnect element
55. FIG. 4(L) shows the state after these carrier layers 54 and 36
have been removed.
[0068] Following this, each of the aforementioned etching barrier
layers 58 and 38 FIG. 4(L) are removed as shown in FIG. 4(M).
[0069] This type of method for manufacturing fabricates an
interconnect element 55 or a wiring board such as shown in FIG.
4(M) wherein interconnection patterns 60 and 42 are provided as
metal patterns embedded in recesses in each of the first and second
major surfaces of the interlayer insulation layer 50 so that the
outer surfaces of the interconnect patterns and those major
surfaces are co-planar.
[0070] Furthermore, because the fabrication processes for the two
interconnect elements or wiring boards progress simultaneously for
both sides until the interconnect elements are separated from the
core material 30, this can improve the manufacturing efficiency and
can increase the productivity.
[0071] FIGS. 5(H) through (K) are cross-sectional diagrams
illustrating the series of processes for simultaneously fabricating
two interconnect elements in a variation of the embodiment shown in
FIGS. 3(A)-3(H) and FIGS. 4(I)-4(M).
[0072] In this embodiment, the same structure as shown in FIG. 3(H)
is prepared, according to the processing described above relative
to FIGS. 3(A)-3(H). Thereafter, the processes differ from the
embodiment described above relative to FIGS. 4(I)-4(M). FIG. 5(H)
illustrates the same structure as that shown in FIG. 3(H).
[0073] Following this, as shown in FIG. 5(I), metal layers 59 and
59 are provided on opposite sides of the core material 30. The
metal layers including or consisting essentially of, for example,
copper, are joined, bonded or adhered to the interlayer insulation
layers 50 and 50 through the application of heat and pressure.
Doing so causes the parts of the metal layers 59 and 59 to form
secure connections having excellent conductivity to the metal posts
or electrically conductive pillars 48 and 48, because the
conductive connections are made through metal-to-metal contact,
e.g., copper-copper bonding. In addition, other parts of the metal
layers 59 and 59 adhere well to outer surfaces of the interlayer
insulation layers 50 and 50.
[0074] Following this, as shown in FIG. 5(J) interconnect patterns
61 and 61 are fabricated through patterning, e.g.,
photolithographically patterning an overlying mask layer and
selectively etching the aforementioned metal layers 59 and 59 from
within openings in that mask layer.
[0075] Following this, in the same manner as shown and described
above relative to FIG. 4(K), cutting is performed in the unneeded
region part adhered by the adhesive sheet 34, after which the
former carrier layers 36 and 36 (FIG. 4(I)) are removed. During
such process, the etching barrier layers 38 (FIG. 4(I)) whereon the
interconnection layers 61 and 61 are formed are used as masks.
Finally, the etching barrier layers 38 can be removed to provide a
pair of interconnect elements 65 joined together via adhesive
layers 36 and a core 30. These interconnect elements 65 can then be
separated from the core as described above relative to FIG. 4(M) to
provide a pair of interconnect elements 65 joined together via
adhesive layers 36 and a core 30. These interconnect elements 65
can then be separated from the core as described above relative to
FIG. 4(K).
[0076] When this is done, first interconnect patterns 61, overlying
one major surface 63 of the interlayer insulation layer (dielectric
element), protrude above the major surface 63 of the interlayer
insulation layer 50, as shown in FIG. 5(J). On the other hand,
although there are indentations and protrusions on one major
surface 63 of the interlayer insulation layer 50, the metal
interconnect patterns 42 are embedded in the other major surface 67
of interlayer insulation layer 50 so that outer surfaces 69 of
those interconnect patterns 42 are co-planar with that major
surface 67. Accordingly, an interconnect element or a wiring board
of a double-sided interconnection type is provided.
[0077] Following this stage of fabrication, as shown in FIG. 5(K),
the interconnect elements 65 can be joined together in a multilayer
interconnect element having a different arrangement, e.g., through
a central connecting element other than the above-described core
30. In one example, the interconnect elements 65 are joined
together through heat and pressure to opposite sides of a
dielectric connecting element 75 or "core connector." Such core
connector 75 may or may not have conductive patterns on metallic or
conductive posts, vias or metallic connectors extending vertically
therethrough. In a particular example, the protruding interconnect
patterns 61 face inward, i.e., toward the dielectric connecting
element, and the interconnect patterns 42 face outward. In this
way, the interconnect patterns 42, which are co-planar with the
exposed major surfaces of the dielectric elements 50 face outward.
In such case, the aforementioned interconnect element or a wiring
board is well suited to manufacturing a multilayer interconnect
element 65 or wiring board having embedded interconnect patterns 42
such that it is flat on its outermost surfaces 69.
[0078] FIGS. 6(A) through (D) are cross-sectional diagrams showing
the series of processes in a third embodiment according to the
present invention.
[0079] As is shown in FIG. 6 (A), a core substrate 70, and two
outer interconnect elements 72 and 72 are provided which face
opposite (front and rear) surfaces of the core substrate 70. The
core substrate 70, in the present example, has four interconnect
layers, where 74 is an interlayer insulation layer, 76 are inner
interconnect patterns 78 are outer interconnect patterns, and 80 is
a bump for interlayer connections, where the outer interconnect
patterns 78 protrude above the outer major surfaces 79. Thus, the
outer (major) surfaces 79 have protrusions and indentations.
[0080] Each of the aforementioned outer interconnect elements 72
and 72 includes interconnect patterns 86, which include or consist
essentially of a metal such as copper which overlies an etching
barrier layer 84. The etching barrier includes or consists
essentially of a material such as, for example, nickel, which is
not attached by an etchant which attacks the metal from which
interconnect patterns 86 are made. The etching barrier layer 84, in
turn, overlies a carrier layer 82, preferably including or
consisting essentially of copper. A plurality of metal posts or
electrically conductive pillars 88, preferably including or
consisting essentially a metal such as copper extend from the
interconnect patterns 86. An interlayer insulation layer 90 covers
an inner surface of the interconnect patterns 86 and fills a space
between the electrically conductive pillars 88. End surfaces 89 of
the electrically conductive pillars 88 are exposed at an outer
surface 91 of the interlayer insulation layer 90.
[0081] Furthermore, on both surfaces of the core substrate 70,
interconnect elements 72 and 72 are positioned, oriented so that
the end surfaces 89 of the electrically conductive pillars 88 and
88 and the outer surface 91 of the interlayer insulation layer 90
are facing the core substrate 70. The interconnect elements and the
core substrate are aligned so that each of the electrically
conductive pillars 88 and 88 line up with the positions of each of
the outer interconnect patterns 78 and 78 of the core substrate
70.
[0082] Following this, heat and pressure are applied to join, e.g.,
bond, adhere or fuse the aforementioned interconnect elements 72
and 72 onto the exposed surfaces of dielectric layers and
interconnect patterns 78 of the aforementioned core substrate 70.
FIG. 6(B) shows the state after this joining process.
[0083] This joining process not only strongly connects the end
surfaces of each of the electrically conductive pillars 88 and 88
to the outer interconnect patterns 78 of the core substrate 70
through copper-copper bonding, but also integrates, adheres, bonds
or preferably fuses the interlayer insulation layers 74 and 90 to
each other.
[0084] Following this, as shown in FIG. 6(C), the aforementioned
carrier layers 82 and 82 (FIG. 6(B)) are removed through etching,
or the like, using, for example, an etchant that etches the
material of the carrier layer, e.g., copper, without attacking the
material of the etching barrier layer 84, which is preferably
nickel.
[0085] Following this, the aforementioned etching barrier layers 84
are removed through, for example etching, as shown in FIG. 6(D).
When this is done, this can provide a multilayer interconnect
element or wiring board having six layers of interconnection
layers, where the interconnect patterns of each interconnection
layer are co-planar with the outer surfaces of each insulation
layer.
[0086] This type of method for manufacturing can provide a
multilayer interconnect element or wiring board wherein the
outermost surfaces are flat and in which interconnect patterns are
embedded in and are co-planar with those outermost surfaces. Such
method utilizes a core substrate 70 as a base, which has
indentations and protrusions on the surfaces thereof, due to the
interconnection layers 78. Thereafter, the aforementioned
interconnect elements 72 and 72 are aligned and joined thereto so
that the electrically conductive pillars 88 and the exposed
surfaces 91 of the interlayer insulation layers 90 face inward
toward the core substrate 70, and so that the interconnect patterns
86 and 86 face outward.
[0087] Note that although in the embodiment described above, the
number of layers for the core substrate 70 is four, and the number
of layers in the multilayer interconnect element or wiring board
produced therefrom is six, this is only a single example. The
number of layers in the core substrate 70 is not limited to four,
but rather may be a different number of layers, enabling the
provision of a multilayer wiring board having a number of layers
that is two layers more than the number of layers in the core
substrate 70.
[0088] FIGS. 7(A) through (H) and FIGS. 8(A) through (H) are
cross-sectional diagrams showing a fourth embodiment according to
the present invention. FIGS. 7(A) through (H) illustrate a series
of processes for the method of manufacturing an interconnect
element 111 (FIG. 7(H)) to be used at outermost layers of a
multilayer interconnect element or wiring board. FIGS. 8(A) through
(H) illustrate a series of processes for processing a core
interconnect element or wiring board for integrating the
aforementioned interconnect elements 111 with a core wiring board,
and for finishing the multilayer wiring board by further processing
the interconnect elements 111.
[0089] First, the method for manufacturing the interconnect
elements 111 will be explained with reference to FIGS. 7(A) through
(H).
[0090] As is shown in FIG. 7(A), a three-layer metal structure 100
is prepared in a manner such as described above relative to the
structure 2 shown in FIG. 1(A). This three-layer metal structure
includes a metal layer 106 to be fabricated into interconnect
patterns, made from, for example, copper. Such layer 106 overlies
an etching barrier layer 104 made from, for example, nickel, on one
surface of a carrier layer 102, made from, for example, copper. The
structure 100 may be fabricated through, for example, rolling.
[0091] Following this, as is shown in FIG. 7(B), interconnect
patterns 108, including traces, contacts, etc., for example, are
fabricated through selectively etching the aforementioned metal
layer 106 (FIG. 7(A)).
[0092] Following this, on the exposed surfaces of the
aforementioned interconnect patterns 108, as is shown in FIG. 7(C),
a resist layer 110 is deposited and patterned, such as through
photolithography. 112 is a hole that is formed in the
aforementioned resist layer 110, and a metal post or electrically
conductive pillar 114 (FIG. 7(D)), described below, will be formed
in this hole 112.
[0093] Following this, as shown in FIG. 7(D), the electrically
conductive pillar 114 is fabricated preferably by plating a metal
such as, for example, copper, using the aforementioned resist layer
110 as a mask. In this case, the electrically conductive pillar 114
is fabricated so as to protrude slightly from the surface of the
resist layer 110. This is to make it possible in a subsequent
grinding process, to align the tops of the electrically conductive
pillars 114 to a specific height, despite variability in the
plating process.
[0094] Following this, as is shown in FIG. 7(E), the protruding
parts of the aforementioned electrically conductive pillars 114 are
ground to cause the end surfaces thereof to be co-planar with
(i.e., to be on the same plane as) the outer (major) surface 105 of
the resist layer 110.
[0095] Following this, as is shown in FIG. 7(F), the aforementioned
resist layer is removed.
[0096] Following this, as is shown in FIG. 7(G), an interlayer
insulation layer 116 is provided overlying the aforementioned
interconnect patterns 108 and insulating respective ones of the
aforementioned electrically conductive pillars 114. After this
stage of processing, the tops or ends 115 of the electrically
conductive pillars 114 are exposed.
[0097] Following this, the ends of the aforementioned electrically
conductive pillars 114 are polished or ground to adjust the height
and to planarize them to the surface of the interlayer insulation
layer 116, to complete the interconnect element 118, as shown in
FIG. 7(H).
[0098] Note that two of these interconnect elements 118 are
prepared, and provided according to the processes shown in FIG.
8(A) through 8(H).
[0099] The method for manufacturing to provide a multilayer
interconnect element or wiring board according to the present
embodiment will be explained next with reference to FIGS. 8(A)
through (H).
[0100] First, as shown in FIG. 8(A), a core interconnect element or
core wiring board 120 is provided.
[0101] In this core interconnect element 120, four interconnection
layers 122 are provided on the inside thereof, each separated and
insulated from others of the layers 122 by interlayer insulation
layers 124. Metal layers 126 and 126 are provided on the outermost
surfaces.
[0102] Following this, as shown in FIG. 8(B), through holes 128 are
formed extending from the outermost surfaces through the
aforementioned core interconnect element 120.
[0103] Following this, as shown in FIG. 8(C), a through hole
interconnection layer 130 is fabricated by plating a metal such as
copper, for example, using electroless plating or electroplating.
The interconnection layer 130 is formed on the surface of the core
interconnect element 120, including the surface of the
aforementioned through hole 128.
[0104] Following this, as shown in FIG. 8(D), the holes on the
inside of the aforementioned through hole interconnection layer 130
are filled with an electrically conductive paste or an insulating
paste 132, after which the parts of this electrically conductive
past or insulating paste 132 protruding at the top and the bottom
are polished or ground to eliminate protrusions and
indentations.
[0105] Following this, a metal layer 134, including or consisting
essentially of a metal such as copper, for example, is fabricated
on the surface, as shown in FIG. 8(E) by electroless plating and/or
electroplating.
[0106] Following this, as is shown in FIG. 8(F), an interconnection
layer 136 is fabricated through selectively etching the
aforementioned metal layer 134 (FIG. 8(E)), the through hole
interconnection layer 130, and the metal layer 126.
[0107] Following this, as shown in FIG. 8(G), the aforementioned
interconnect elements 118 and 118, manufactured using the method
shown in FIGS. 7(A)-7(H), are aligned and joined to the exposed
surfaces of the aforementioned core substrate 120.
[0108] The interconnect elements 118 and 118 are arranged so that
the ends of the electrically conductively pillars 114 and the
interlayer insulation layers 116 face the exposed surfaces of the
interconnection layer 136 of the core interconnect element 120. The
interconnect elements are aligned so that each of the electrically
conductively pillars 114 are lined up with the interconnection
layers 136 corresponding thereto. Thereafter, pressure and heat are
applied to bond, adhere or fuse the interconnect elements 118 to
the core interconnect element 120.
[0109] Following this, the carrier layers 102 and 102 (FIG. 7(A))
of the aforementioned interconnect elements 118 and 118 are
removed, following which the etching barrier layers 104 and 104
(FIG. 7(A)) are removed. FIG. 8(H) shows the state after these
etching barrier layers have been removed.
[0110] This method of manufacturing produces a multilayer
interconnect element or wiring board that has through holes for
electrical connection between layers thereof and which has flat
outer surfaces.
[0111] FIGS. 9(A) through (I) are cross-sectional diagrams showing
the sequence of processes in a fifth embodiment of the present
invention.
[0112] First, referring to FIGS. 9(A)-9(B), two interconnect
elements used for the outermost layers of the wiring board are
prepared. Referring to FIGS. 9(C)-9(D), one or more interconnect
elements used for intermediate layers are prepared.
[0113] First the interconnect elements 182 (FIG. 9(B)) for the
outermost layers are prepared. For ease of reference, only a single
interconnect element 182 is shown.
[0114] This interconnect element 182 can be made through preparing
a three-layer metal structure 180 (FIG. 9(A)) wherein a metal layer
188, including or consisting essentially of a metal such as copper,
for example, is provided, overlying an etching barrier layer 186,
including or consisting essentially of a metal, which is not
attacked by an etchant which attacks the first metal, e.g. copper.
The metal of which the etching barrier layer is formed may be
nickel, for example. Such layer 186 overlies one surface of a
carrier layer 184 including or consisting essentially of a metal,
such as copper, for example. The metal layer 188 is patterned,
e.g., by photolithographic process to produce an interconnection
layer 190 including interconnect patterns such as traces, contacts,
etc.
[0115] Referring to FIGS. 9(C)-9(D), an interconnect element 194
for an intermediate layer is prepared. Although in FIG. 9(D) only
one interconnect element 194 for an intermediate layer is shown, a
plurality thereof may be provided. Illustratively, in the present
embodiment, three are provided. Each interconnect element 194 for
an intermediate layer can be produced through preparing a
three-layer structure 192 wherein metal layers 198 are fabricated
on both sides of an interlayer insulation layer 196 (FIG. 9(C)),
and these metal layers 198 on both sides are then patterned, such
as by photolithographic processes.
[0116] Following this, a plurality, or in the example as
specifically shown, three interconnect elements 194 are stacked
with interlayer insulation layers 202 interposed there between,
after which the aforementioned interconnect elements for the
outermost layers 182 are stacked at specific positions on both
outside surfaces of the stack. Thereafter, heat and pressure are
applied to join the interconnect elements 182 as outermost layers
with the interconnect elements 194 disposed between them to join
the components 202, 194, 194, 194, and 202. FIG. 9(E) shows the
state after these components have been joined.
[0117] Following this, the carrier layers 184 (FIG. 9(A)) are
removed from the outermost surfaces of the layered unit that has
been integrated as described above, after which the etching barrier
layers 186 are removed, following which through holes 204 are
provided in specific locations. FIG. 9(F) shows the state after the
through holes 204 have been formed.
[0118] Following this, a plated underlayer 206, including or
consisting essentially of a metal such as copper, for example is
fabricated by electroless plating on the surface of the
aforementioned layered unit, including the inner peripheral surface
of the aforementioned through holes 204, after which a resist layer
208, which will serve as the mask layer for through hole
fabrication, is deposited and patterned, e.g. by photolithography.
FIG. 9(G) shows the state after the fabrication of this resist
layer 208.
[0119] Following this, as shown in FIG. 9(H), the aforementioned
resist layer 208 is used as a mask to fabricate a through hole
interconnection layer 210, including or consisting essentially of a
metal such as copper, for example on top of the aforementioned
plated underlayer 206. Note that the fact that the inner peripheral
surface of the aforementioned through hole interconnection layer
210 may be filled with an electrically conductive paste or an
insulating paste 132 is the same as the case of the embodiment
shown in FIG. 8(D).
[0120] Following this, the aforementioned resist layer 208 (FIG.
9(G) is removed, and the aforementioned plated underlayer 206 is
also removed to expose the interconnection layer 190. This can
provide a multilayer wiring board that uses the through hole
interconnection layer 210 as an interlayer connection means to
enable greater levels of integration by allowing a great number of
intermediate interconnect elements 195 each having an
interconnection layer to be joined and electrically connected
together in one multilayer interconnect element.
[0121] FIGS. 10(A) through (H) are cross-sectional diagrams of a
series of processes according to a sixth embodiment of the present
invention.
[0122] As is shown in FIG. 10(A), a three-layer metal structure 140
is prepared. This three-layer metal structure 140 has a metal
underlayer 146, including or consisting essentially of a metal such
as copper, for example, layered on top of an etching barrier layer
144 including or consisting essentially of a metal such as nickel,
for example. The etching barrier layer in turn overlies a surface
of a carrier layer 142, which includes or consists essentially of a
metal such as copper, for example. The metal structure 140 may be
fabricated through rolling, for example.
[0123] Following this, as shown in FIG. 10(B), a first photo-resist
layer 148 is deposited and patterned over the aforementioned metal
structure 140. Following this, as shown in FIG. 10(C), an
interconnection layer 150 including metal interconnect patterns,
e.g., traces and/or contacts is fabricated through plating a metal,
for example, copper, using the aforementioned resist layer 148 as a
mask, after which a surface roughening process is performed for
roughening the surface of this interconnection layer 150.
[0124] Following this, as shown in FIG. 10(D), a second resist
layer 152 is deposited and patterned to overlie the first
photoresist layer 148. 154 is a hole that is formed in the resist
layer 152, where an electrically conductive pillar 156 (FIG. 10(E))
described below, will be formed therein.
[0125] Following this, as shown in FIG. 10(E), a metal post or
other electrically conductive pillar 156 is fabricated through
plating a metal, for example, copper, using as a mask the
aforementioned second resist layer 152. These electrically
conductive pillars 156 are fabricated on the roughened surface of
the interconnection layer 150, enabling excellent adhesion between
the interconnection layer 150 and the electrically conductive
pillar 156, and enabling excellent contact properties.
[0126] Following this, as shown in FIG. 10(F), the aforementioned
second resist layer 152 is removed. 158 is an interconnect element
that results after removing such layer 152.
[0127] Following this, a second interconnect element 158a,
structured from the aforementioned interconnect element 158, with
the electrically conductive pillars 156 removed from the
interconnect element 158 (or, more precisely, a structure wherein
the electrically conductive pillars 156 were not fabricated) is
provided.
[0128] Given this, the surface 155 of the interconnect element 158
from which the electrically conductive pillars 156 and the
interconnection layer 150 extend and the surface 155 from which the
interconnection layer 150 of the interconnect element 158a extends
are disposed facing each other, and aligned so that each of the
electrically conductive pillars 156 of interconnect element 158
contacts the corresponding interconnection layer 150 of
interconnect element 158a. An interlayer insulation layer 160 is
interposed between the interconnect element 158a and the
interconnect element 158. In this state, heat and pressure are
applied to join, e.g. bond, adhere or fuse the interconnect
elements 158a and 158 together. FIG. 10(G) shows the state after
this joining process.
[0129] Following this, the carrier layers 142 and 142 of the
interconnect elements 158 and 158a are removed, after which the
etching barrier layers 144 and 144 are also removed. Thereafter,
the aforementioned metal underlayers 146 and 146 are also
removed.
[0130] This provides a multilayer interconnect element or wiring
board wherein interconnection layers 150 are fabricated on both
surfaces of an interlayer insulation layer 160, co-planar
therewith. FIG. 10(H) shows the wiring board that is produced
through the removal of the metal underlayers 146 and 146.
[0131] The multilayer interconnect elements or wiring boards shown
and described in this embodiment are similar to those described
above, having a structure in which outermost surfaces of the
dielectric elements are flat and interconnect patterns exposed at
those surfaces are co-planar thereto.
[0132] On the other hand, with reference to FIGS. 10(A) through
10(H) the interconnect elements are aligned and joined together and
integrated in a state wherein the surfaces on the ends of the
electrically conductive pillars 156 are in contact with the
corresponding interconnection layer 150. The aforementioned carrier
layers 142 and 142 of each of the aforementioned interconnect
elements 158 and 158a, the aforementioned etching barrier layers
144 and 144, and the aforementioned metal underlayers 146 and 146
are removed sequentially.
[0133] Referring to FIG. 10(H), while the interconnect element 158
on which the electrically conductive pillars 156 are fabricated,
and the interconnect element 158a that is structured without these
electrically conductive pillars, are layered with an interlayer
insulation layer 160 interposed between them. In a variation of
such embodiment, interconnect elements 158 and 158, which have
electrically conductive pillars 156 extending therefrom can be
joined such that the electrically conductive pillars 156 and 156
contact each other, as integrated within an interlayer insulation
layer 160 interposed between the two interconnect elements 158.
[0134] FIGS. 11 (A) through 11(F) and FIGS. 12(G)-12(I) are
sectional drawings illustrating a method of manufacturing a
multi-layer circuit board in accordance with another embodiment of
the present invention.
[0135] In a preliminary stage of manufacturing shown in FIG. 11(A),
a three-layer metal plate 200 is prepared. The three-layer metal
plate 200 includes a support plate 202 which preferably consists
essentially of a first metal such as copper. An etch stop layer 204
is disposed to overlie the surface of the support plate, it
consisting of an etch distinguishable material such as nickel which
is not attacked by a particular etchant that attacks copper.
Preferably, the etch stop layer has a thickness which is at least
somewhat less than the thickness of the support plate. A third
metal layer 206, also preferably consisting essentially of copper,
is disposed overlying a rear face of the etch stop layer opposite
the support plate. The third metal layer 206 functions as a layer
from which circuit wiring patterns will be patterned.
[0136] Next, as shown in FIG. 11(B), conductive wiring patterns
208, and 208' are formed by selectively etching the aforesaid metal
layer 206. Patterned wiring films 208 and 208' may have different
functions and different widths 209 and may be oriented in
substantially different directions. Next, as illustrated in FIG. 11
(C), a pair of patterned three-layer metal plates 200 having
exposed wiring patterns 208, 208' are laminated together with an
intermediate insulating layer 210 to form a unit in which the
wiring patterns 208 208' face inward towards the center of the
insulating layer 210 and are embedded at the external surfaces 211
of the insulating layer. This lamination can be performed by
application of heat and pressure, for example.
[0137] Subsequently, as shown in FIG. 11(D), the support plates are
removed from the intermediate etch stop layers 204. A through hole
212 (FIG. 11(E)) is then formed to extend through the insulating
layer 210 and the etch stop layers 204 and wiring films 208 on the
exposed surfaces of the insulating layer.
[0138] Next, as shown in FIG. 11(F), a conductive film 214
consisting essentially of copper, for example, is formed to overlie
the etch stop layers 204 and insulating layer 210 and within the
inner surface of the through hole 212. The conductive film is
preferably formed by processing such as electroless plating and/or
electroplating a metal such as copper.
[0139] Subsequently, as illustrated in FIG. 12(G), a resist film is
then formed on the surface of the conductive film 214 and
photolithographically processed to form resist patterns 216.
Referring to FIG. 12(H), the conductive film 214 on both faces of
the insulating layer is then etched together with the etch stop
layers that underlie them, using the aforesaid 216 resist patterns
as a mask. As a result of this etching, two conductive film
patterns are produced. A through hole conductive film 218 overlies
an interior surface of the through hole 212 and conductively
connects portions of the external wiring patterns 208 which are
embedded in each face of the insulating layer 210. A second
conductive film 220 is simultaneously formed by this etching
process, this conductive film being referred to as a projecting
conductive film 220. Subsequently, the projecting cover film 220
can be used for interconnecting the wiring substrate to an external
component, for example, an integrated microelectronic or
micro-electromechanical device or ("chip"), or to a substrate of a
packaged chip.
[0140] Next, as shown in FIG. 12(I), an insulating cover film 222
is provided at positions overlying the exposed wiring patterns 208
while leaving the projecting conductive film 220 exposed above the
surface of the wiring substrate 201. In one embodiment, the cover
film is provided by applying a pre-formed film having an adhesive
property from a roll. In another embodiment, the cover film is
provided by deposition and subsequent patterning, e.g., by
photolithography.
[0141] Preferably, the underside of the cover film 222, i.e., the
surface 225 of the film which faces the insulating layer 210, is
substantially smooth, rather than rough. This makes the cover film
easy to apply and to position in relation to the insulating layer
210. In such way, the cover film can be applied so that its
position is not misaligned with the projecting conductive film 220
or an escape hole 224 that opens for it.
[0142] In addition, since the inner surface 225 of the cover film
is not rough, it is easier to apply to the insulating layer and
there is reduced risk that the cover film will contact a corner of
the wiring film 208 and be damaged in the process, causing its
protective effect to be reduced.
[0143] The wiring substrate 201 in accordance with FIG. 12(I)
provides advantages in permitting external interconnection between
wiring film 208' and an external circuit element through projecting
conductive film 220. At the same time, other wiring patterns 208 of
the substrate are protected against shorting, bridging or other
unwanted electrical interaction with external circuit elements by
virtue of the insulating cover film 222 provided thereon. In
addition, a conductive film 218 provided within the through hole
provides interconnection between the wiring patterns 208 at each of
the upper and lower faces of the insulating layer.
[0144] FIG. 13 is a cross-sectional view illustrating a wiring
substrate 203 according to a variation of the embodiment shown in
FIG. 12(I). In this embodiment, different sets of the embedded
wiring patterns 208a and 208b on the same face of the insulating
layer 210 are conductively interconnected by a crossover conductive
film 226 patterned to overlie the surface of the insulating layer
210. Preferably, the crossover conductive film is formed
simultaneously with the through hole conductive film 218 and
projecting conductive film 220 in a manner similar to that
described above with reference to FIGS. 12(F), 12(G) and 12(H).
[0145] As further illustrated in FIG. 13, a lead 228 of an
electronic component, e.g., a lead of a packaged chip, for example,
can be inserted into the through hole of the substrate in contact
with the through hole conductive film 218 and soldered or otherwise
bonded thereto to provided interconnection between the wiring
substrate 203 and such packaged chip.
[0146] FIGS. 14 (A) and 14(B) further illustrate surface mount
interconnections between a packaged chip 240 and a wiring substrate
205 in accordance with an embodiment of the invention. In this
case, the wiring substrate 205 may be the same as or similar to one
of the above-described substrates, e.g., wiring substrate 201 (FIG.
12(I)) or wiring substrate 203 (FIG. 13). Alternatively, a simpler
form of wiring substrate can be utilized which includes, at
minimum, conductive wiring patterns 208' embedded in recesses 232
at an external surface 234 of an insulating layer 230. A projecting
conductive film 220, or a metal interconnection post or pad
projects above the exposed surface of the wiring patterns 208',
that surface being defined by the external surface 234 of the
insulating layer 230. Preferably, the conductive film is formed by
the deposition and masked etching of a metal layer preferably
including copper, or is formed by electroless plating and/or
electroplating.
[0147] The packaged chip includes the chip 246 as mounted to a
package substrate 242, shown here in exemplary fashion as a
dielectric element 248 having conductive wiring patterns 244 on one
face, that face being the side to which the chip 246 is
mounted.
[0148] As particularly shown in FIG. 14(A), the packaged chip 240
is pressed and held against the wiring substrate 205 through an
anisotropic conductive film ("ACF") 246 to conductively
interconnect the two components, forming an assembly as illustrated
in FIG. 14(B). Conductive interconnection is established only where
the ACF 246 is compressed to a significant extent, that is at a
location such as between the projecting conductive film 220 and the
opposed mounting surface 244 of the packaged chip.
[0149] Other embedded wiring patterns in the substrate 230 which
are in contact with the ACF 246 but not in contact with the
projecting conductive film 220 are not at risk for producing
unwanted conductive interconnections, e.g., becoming
short-circuited. This is because the ACF 246 is compressed only
where it overlies features such as the projecting conductive film
220 that extends above the surface 234 of the surface. In addition,
by appropriately controlling the width 236 of the projecting
conductive film 220, the force applied to compress the ACF 246
against wiring 244 can be spread over a selected surface area to
assure both adequacy of contact pressure and adequacy of the
surface area through the current-bearing interface between the two
components to reduce resistance.
[0150] As these and other variations and combinations of the
features set forth above can be utilized, the foregoing description
of the preferred embodiment should be taken by way of illustration
rather than by limitation of the invention.
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