U.S. patent application number 14/609848 was filed with the patent office on 2015-08-06 for electroless plating method, electroless plating apparatus and storage medium.
The applicant listed for this patent is Tokyo Electron Limited. Invention is credited to Mitsuaki Iwashita, Nobutaka Mizutani, Takashi Tanaka.
Application Number | 20150218702 14/609848 |
Document ID | / |
Family ID | 53754336 |
Filed Date | 2015-08-06 |
United States Patent
Application |
20150218702 |
Kind Code |
A1 |
Mizutani; Nobutaka ; et
al. |
August 6, 2015 |
ELECTROLESS PLATING METHOD, ELECTROLESS PLATING APPARATUS AND
STORAGE MEDIUM
Abstract
A multiple number of accurately-patterned metal layers can be
formed on a substrate. On a substrate 11, a patterned first metal
layer 12 is formed (see FIG. 1A), and then, a metal sacrificial
layer 15 is formed on the first metal layer 12 (see FIG. 1B).
Further, an aqueous solution containing an ionized metal allowed to
be substituted with a metal of the metal sacrificial layer 15 is
coated on the metal sacrificial layer 15, so that a catalyst layer
16 is formed on the metal sacrificial layer 15 (see FIG. 1E) .
Thereafter, a second metal layer 18 is formed on the catalyst layer
16 by performing an electroless plating process (see FIG. 1F).
Furthermore, the substrate 11 is etched by using the second metal
layer 18 as a mask.
Inventors: |
Mizutani; Nobutaka;
(Nirasaki City, JP) ; Iwashita; Mitsuaki;
(Nirasaki City, JP) ; Tanaka; Takashi; (Nirasaki
City, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tokyo Electron Limited |
Tokyo |
|
JP |
|
|
Family ID: |
53754336 |
Appl. No.: |
14/609848 |
Filed: |
January 30, 2015 |
Current U.S.
Class: |
427/265 ;
118/400; 118/697 |
Current CPC
Class: |
C23C 18/54 20130101;
C23C 18/1608 20130101; C23C 18/1651 20130101; C23C 18/32 20130101;
C23C 18/165 20130101; C23C 18/1831 20130101; C23C 18/1619
20130101 |
International
Class: |
C23C 18/16 20060101
C23C018/16; C23C 18/48 20060101 C23C018/48; C23C 18/32 20060101
C23C018/32 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 31, 2014 |
JP |
2014-017694 |
Claims
1. An electroless plating method of performing an electroless
plating process on a substrate on which a patterned first metal
layer made of a metal compound which does not have catalytic
property and a metal sacrificial layer are formed in sequence, the
electroless plating method comprising: forming a catalyst layer on
the metal sacrificial layer by coating, on the metal sacrificial
layer, an aqueous solution containing an ionized metal allowed to
be substituted with a metal of the metal sacrificial layer; and
forming a second metal layer by performing the electroless plating
process on the catalyst layer.
2. The electroless plating method of claim 1, further comprising:
forming the patterned first metal layer formed of the metal
compound which does not have the catalytic property on the
substrate before the forming of the catalyst layer; and forming the
metal sacrificial layer on the first metal layer.
3. The electroless plating method of claim 1, wherein the metal
compound of the first metal layer is formed of TiN or TaN.
4. The electroless plating method of claim 1, wherein the metal of
the metal sacrificial layer is formed of Ti, W, Cu, Ni or Co.
5. The electroless plating method of claim 1, wherein a metal of
the catalyst layer is formed of Pd, Au or Pt.
6. The electrodes plating method of claim 1, wherein the second
metal layer is formed of an electroless plating layer of Ni.
7. An electroless plating apparatus that performs an electroless
plating process on a substrate on which a patterned first metal
layer made of a metal compound which does not have catalytic
property and a metal sacrificial layer are formed in sequence, the
electroless plating apparatus comprising: a catalyst layer forming
unit configured to form a catalyst layer on the metal sacrificial
layer by coating, on the metal sacrificial layer, an aqueous
solution containing an ionized metal allowed to be substituted with
a metal of the metal sacrificial layer; and a second metal layer
forming unit configured to form a second metal layer by performing
the electroless plating process on the catalyst layer.
8. The electroless plating apparatus of claim 7, further
comprising: a first metal layer forming unit configured to form the
patterned first metal layer formed of the metal compound which does
not have the catalytic property on the substrate before forming the
catalyst layer; and a metal sacrificial layer forming unit
configured to form the metal sacrificial layer on the first metal
layer.
9. The electroless plating apparatus of claim 7, wherein the metal
compound of the first metal layer is formed of TiN or TaN.
10. The electroless plating apparatus of claim 7, wherein the metal
of the metal sacrificial layer is formed of Ti, W, Cu, Ni or
Co.
11. The electroless plating apparatus of claim 7, wherein a metal
of the catalyst layer is formed of Pd, Au or Pt.
12. The electrodes plating apparatus of claim 7, wherein the second
metal layer is formed of an electroless plating layer of Ni.
13. A computer-readable storage medium having stored thereon
computer-executable instructions that, in response to execution,
cause an electroless plating apparatus to perform an electroless
plating method of performing an electroless plating process on a
substrate on which a patterned first metal layer made of a metal
compound which does not have catalytic property and a metal
sacrificial layer is formed in sequence, wherein the electroless
plating method comprises: forming a catalyst layer on the metal
sacrificial layer by coating, on the metal sacrificial layer, an
aqueous solution containing an ionized metal allowed to be
substituted with a metal of the metal sacrificial layer; and
forming a second metal layer by performing the electroless plating
process on the catalyst layer.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of Japanese Patent
Application No. 2014-017694 filed on Jan. 31, 2014, the entire
disclosures of which are incorporated herein by reference.
TECHNICAL FIELD
[0002] The embodiments described herein pertain generally to an
electroless plating method and an electroless plating apparatus of
forming an electroless plating layer on a substrate, and a storage
medium therefor.
BACKGROUND
[0003] In an LSI (Large-Scale Integrated circuit) manufacturing
process, a metal is grown on the entire surface of a substrate
through the CVD or the PVD to be formed. In the past, patterning of
the metal is performed by the etching with a chemical liquid or the
dry-etching of Al wiring. Recently, the patterning of the metal is
performed through a BEOL process in which an insulating layer is
dry-etched, a wiring metal such as Cu is buried within a formed
groove and then the metal is etched by the CMP (Patent Document
1).
[0004] In such a metal patterning process, a substrate is prepared
first, and a multiple number of metal layers are formed on the
substrate through the PVD or the CVD. Then, a resist pattern is
formed on the multiple metal layers, and the multiple metal layers
are etched with the resist pattern.
[0005] If the multiple metal layers are formed thickly on the metal
and later dry-etched together, it takes a long time with a current
dry-etching technique, so that a load of the etching process is
increased. Further, depending on the kinds of the metal (for
example, Cu), it is difficult to dry-etch the metal, and the metal
cannot be etched accurately. As a result, it is very difficult to
form, on the substrate, multiple metal layers which are patterned
accurately.
[0006] Patent Document 1: Japanese Patent Laid-open Publication No.
H11-297699
SUMMARY
[0007] In view of the foregoing problems, an example embodiment
provides an electroless plating method and an electroless plating
apparatus to be allowed to form an accurately-patterned metal layer
on a substrate and, also to form, on the metal layer, a metal layer
on which patterning by dry-etching does not need to be
performed.
[0008] In one example embodiment, an electroless plating method
performs an electroless plating process on a substrate on which a
patterned first metal layer made of a metal compound which does not
have catalytic property and a metal sacrificial layer are formed in
sequence. The electroless plating method includes forming a
catalyst layer on the metal sacrificial layer by coating, on the
metal sacrificial layer, an aqueous solution containing an ionized
metal allowed to be substituted with a metal of the metal
sacrificial layer; and forming a second metal layer by performing
the electroless plating process on the catalyst layer.
[0009] In another example embodiment, an electroless plating
apparatus performs an electroless plating process on a substrate on
which a patterned first metal layer made of a metal compound which
does not have catalytic property and a metal sacrificial layer are
formed in sequence. The electroless plating apparatus includes a
catalyst layer forming unit configured to form a catalyst layer on
the metal sacrificial layer by coating, on the metal sacrificial
layer, an aqueous solution containing an ionized metal allowed to
be substituted with a metal of the metal sacrificial layer; and a
second metal layer forming unit configured to form a second metal
layer by performing the electroless plating process on the catalyst
layer.
[0010] In yet another example embodiment, a computer-readable
storage medium has stored thereon computer-executable instructions
that, in response to execution, cause an electroless plating
apparatus to perform an electroless plating method of performing an
electroless plating process on a substrate on which a patterned
first metal layer made of a metal compound which does not have
catalytic property and a metal sacrificial layer is formed in
sequence. Further, the electroless plating method includes forming
a catalyst layer on the metal sacrificial layer by coating, on the
metal sacrificial layer, an aqueous solution containing an ionized
metal allowed to be substituted with a metal of the metal
sacrificial layer; and forming a second metal layer by performing
the electroless plating process on the catalyst layer.
[0011] According to the example embodiment, it is possible to form
a multiple number of accurately-patterned metal layers on a
substrate easily and securely.
[0012] The foregoing summary is illustrative only and is not
intended to be in any way limiting. In addition to the illustrative
aspects, embodiments, and features described above, further
aspects, embodiments, and features will become apparent by
reference to the drawings and the following detailed
description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] In the detailed description that follows, embodiments are
described as illustrations only since various changes and
modifications will become apparent to those skilled in the art from
the following detailed description. The use of the same reference
numbers in different figures indicates similar or identical
items.
[0014] FIG. 1A to FIG. 1G are diagrams illustrating a sequence of
an electroless plating method in accordance with an example
embodiment;
[0015] FIG. 2 is a block diagram illustrating an electroless
plating apparatus in accordance with the example embodiment;
and
[0016] FIG. 3A and FIG. 3B are diagrams illustrating a conventional
method of forming multiple metal layers as a comparative
example.
DETAILED DESCRIPTION
[0017] In the following detailed description, reference is made to
the accompanying drawings, which form a part of the description. In
the drawings, similar symbols typically identify similar
components, unless context dictates otherwise. Furthermore, unless
otherwise noted, the description of each successive drawing may
reference features from one or more of the previous drawings to
provide clearer context and a more substantive explanation of the
current example embodiment. Still, the example embodiments
described in the detailed description, drawings, and claims are not
meant to be limiting. Other embodiments may be utilized, and other
changes may be made, without departing from the spirit or scope of
the subject matter presented herein. It will be readily understood
that the aspects of the present disclosure, as generally described
herein and illustrated in the drawings, may be arranged,
substituted, combined, separated, and designed in a wide variety of
different configurations, all of which are explicitly contemplated
herein.
[0018] Hereinafter, example embodiments will be described with
reference to FIG. 1A to FIG. 2.
[0019] A metal layer forming method in accordance with an example
embodiment includes, as depicted in FIG. 1A to FIG. 1F, forming a
first metal layer 12, a metal sacrificial layer 15, a catalyst
layer 16 and a second metal layer 18 in sequence on a silicon
substrate (hereinafter, simply referred to as "substrate") 11
formed of a semiconductor wafer or the like. Here, a thickness of
the whole metal layers including the first metal layer 12, the
metal sacrificial layer 15, the catalyst layer 16 and the second
metal layer 18 is set to be equal to a thickness of a metal layer
including a first metal layer 12 and the second metal layer 18 of a
comparative example to be described later, as depicted in FIG. 3A
and FIG. 3B.
[0020] In this case, a substrate main body made of Si may be used
as the substrate 11. Further, a structure having a substrate main
body made of Si and a TEOS layer formed on the substrate main body
may be used as the substrate 11.
[0021] Now, an electroless plating apparatus 30 configured to form
the first metal layer 12, the metal sacrificial layer 15, the
catalyst layer 16 and the second metal layer 18 on the substrate 11
will be explained with reference to FIG. 2.
[0022] The electroless plating apparatus 30 includes a first metal
layer forming unit 31; a metal sacrificial layer forming unit 32; a
catalyst layer forming unit 33; and a second metal layer forming
unit 34. The first metal layer forming unit 31 is configured to
form the first metal layer 12 made of a metal compound which does
not have catalytic property on the substrate 11. The metal
sacrificial layer forming unit 32 is configured to form the metal
sacrificial layer 15 on the first metal layer 12. The catalyst
layer forming unit 33 is configured to form the catalyst layer 16
on the metal sacrificial layer 15 by coating, on the metal
sacrificial layer 15, an aqueous solution containing an ionized
metal allowed to be substituted with a metal of the metal
sacrificial layer 15. The second metal layer forming unit 34 is
configured to form the second metal layer 18 by performing an
electroless plating process on the catalyst layer 16.
[0023] Further, an etching unit 35 configured to perform an etching
process on the substrate 11 with the second metal layer 18 as a
mask to perform a patterning process on the substrate 11 is
provided at the rear end of the catalyst layer forming unit 33 and
the second metal layer forming unit 34.
[0024] Operations of the individual components of the
above-described electroless plating apparatus 30, i.e., the first
metal layer forming unit 31, the metal sacrificial layer forming
unit 32, the catalyst layer forming unit 33, the second metal layer
forming unit 34 and the etching unit 35 are controlled by a
controller 40 according to various kinds of programs recorded in a
storage medium 41 provided in the controller 40, so that various
processes are performed on the substrate 11. Here, the storage
medium 41 stores thereon various kinds of setup data or various
kinds of programs such as a metal layer forming program to be
described later. Here, the storage medium 41 may be implemented by
a computer-readable memory such as a ROM or a RAM, or a disk-type
storage medium such as a hard disk, a CD-ROM, a DVD-ROM or a
flexible disk, as commonly known in the art.
[0025] Now, an operation of the example embodiment having the
above-described configuration will be discussed with reference to
FIG. 1A to FIG. 1G.
[0026] First, the substrate 11 formed of a semiconductor wafer or
the like is transferred into the electroless plating apparatus
30.
[0027] Here, the substrate 11 may have a planar surface (see FIG.
1A), or may have thereon a recess.
[0028] As a way to form the recess on the substrate 11, a commonly
known conventional method may be appropriately employed. To
elaborate, a general-purpose technique using a fluorine-based gas
or a chlorine-based gas may be used as a dry-etching technique, for
example. Especially, to form a hole having a high aspect ratio
(ratio of a depth of the hole to a diameter of the hole), a method
using ICP-RIE (Inductively Coupled Plasma Reactive Ion Etching)
configured to perform a high-speed deep-hole etching may be more
appropriately utilized. Particularly, a method called Bosch
process, in which an etching process using sulfur hexafluoride
(SF.sub.6) and a protection process using a Teflon (registered
trademark)-based gas such as C.sub.4F.sub.8 are performed
repeatedly, may be appropriately employed.
[0029] Then, in the electroless plating apparatus 30, the substrate
11 is loaded into the first metal layer forming unit 31. In this
first metal layer forming unit 31, the patterned first metal layer
12 is formed on the substrate 11.
[0030] To elaborate, as depicted in FIG. 1A, the first metal layer
12 made of TiN or TaN is formed on the substrate 11 by the CVD or
the PVD. Here, the TiN or TaN is formed of a metal compound which
does not have the catalytic property for a second metal layer 18 to
be formed by the electroless plating process, as will be described
later.
[0031] Subsequently, the substrate 11 having thereon the first
metal layer 12 formed thereon is sent into the metal sacrificial
layer forming unit 32. In this metal sacrificial layer forming unit
32, the metal sacrificial layer 15 is formed on the first metal
layer 12 (see FIG. 1B).
[0032] The metal sacrificial layer 15 contains a metal allowed to
be substituted with a metal forming the catalyst layer 16 to be
described later. The metal sacrificial layer 15 is formed on the
first metal layer 12 by the CVD or the PVD in the metal sacrificial
layer forming unit 32.
[0033] Further, the metal sacrificial layer 15 may be formed on the
first metal layer 12 as a continuous film to have a thickness
smaller than that of the first metal layer 12, or may be formed on
the first metal layer 12 as a discontinuous film. Furthermore, the
metal sacrificial layer 15 may be formed in a particulate shape. A
thickness of a metal layer formed of the first metal layer 12 and
the metal sacrificial layer 15 is set to be smaller than a
thickness of a metal layer formed of the first metal layer 12 and
the second metal layer 18 in the prior art shown in FIG. 3A and
FIG. 3B.
[0034] Afterwards, a resist pattern 13 is formed on the first metal
layer 12 and the metal sacrificial layer 15. Then, by performing
the etching process on the first metal layer 12 and the metal
sacrificial layer 15 on which the resist pattern 13 is formed, the
first metal layer 12 and the metal sacrificial layer 15 are
patterned (see FIG. 1C). Thereafter, the resist pattern 13 is
removed from the first metal layer 12 and the metal sacrificial
layer 15 (see FIG. 1D).
[0035] One of Ti, W, Cu, Ni and Co may be used as a metal that
forms the metal sacrificial layer 15.
[0036] Subsequently, the substrate 11, in which the metal
sacrificial layer 15 is formed on the first metal layer 12, is sent
into the catalyst layer forming unit 33. In the catalyst layer
forming unit 33, an aqueous solution containing an ionized metal
allowed to be substituted with the metal of the metal sacrificial
layer 15 is coated on the metal sacrificial layer 15 on the
substrate 11, so that the catalyst layer 16 is formed on the metal
sacrificial layer 15 (see FIG. 1E).
[0037] To elaborate, in case that the metal sacrificial layer 15 is
made of Ti or W, an aqueous solution such as palladium (Pd)
chloride solution or palladium (Pd) sulfate solution is coated on
the metal sacrificial layer 15. In this case, Ti or W of the metal
sacrificial layer 15 is substituted with Pd ions in the aqueous
solution, so that the Pd ions are precipitated on the metal
sacrificial layer 15.
[0038] Accordingly, the catalyst layer 16 made of any one of Pd, Au
and Pt can be formed on the metal sacrificial layer 15.
[0039] Thereafter, the substrate 11 having thereon the catalyst
layer 16 is sent to the second metal layer forming unit 34. In this
second metal layer forming unit 34, the electroless plating process
is performed on the substrate 11, so that the second metal layer 18
is formed.
[0040] To be specific, by performing the electroless plating
process of a Ni metal on the substrate 11, the plating process in
which the Pd metal of the catalyst layer 16 is used as a catalyst
is performed on the substrate 11, so that, the second metal layer
18 made of the Ni metal is formed on the catalyst layer 16 (see
FIG. 1F).
[0041] At this time, the second metal layer 18 formed through the
electroless plating process is set to have a thickness
substantially same to the thickness of the metal layer formed of
the first metal layer 12 and the second metal layer 18 of a
comparative example in FIG. 3A and FIG. 3B. The second metal layer
18 of the present example embodiment is selectively formed only on
the patterned metal layer.
[0042] Further, in the second metal layer forming unit 34, the
electroless plating process may be performed by using a Cu metal
instead of the Ni metal. In such a case, the second metal layer 18
made of the Cu metal may be formed on the catalyst layer 16.
[0043] Thereafter, the substrate 11 having thereon the second metal
layer 18 is sent to the etching unit 35. In this etching unit 35,
the etching process is performed on the substrate 11 with the
second metal layer 18 as a mask (see FIG. 1G).
[0044] In accordance with the present example embodiment, after the
first metal layer 12 and the metal sacrificial layer 15 are formed
on the substrate 2, the first metal layer 12 and the metal
sacrificial layer 15 are etched by using the resist pattern 13.
Then, the catalyst layer 16 is formed on the first metal layer 12
and the metal sacrificial layer 15 which are patterned. Then, by
performing the electroless plating process with the catalyst layer
16, the second metal layer 18 is formed. Accordingly, since the
thin metal layer formed of the first metal layer 12 and the metal
sacrificial layer 15 can be dry-etched with the resist pattern 13,
a load of the etching process can be reduced, so that it is
possible to obtain the first metal layer 12 and the second metal
layer 18 which are patterned accurately. Furthermore, as compared
to a case that a metal layer is formed on the entire surface of the
substrate 11 through the CVD or the PVD, the second metal layer 18
can be selectively formed only on the patterned first metal layer
12 and metal sacrificial layer 15 with the catalyst layer 16
therebetween.
[0045] Now, a comparative example will be explained with reference
to FIG. 3A and FIG. 3B. As depicted in FIG. 3A and FIG. 3B, when
forming multiple metal layers on a substrate 11, a first metal
layer 12 made of TiN or TaN and a second metal layer 18 made of Ni
are formed on the substrate 11 through the CVD or the PVD, and,
then, a resist pattern 23 is formed on the second metal layer 18.
Then, by performing an etching process with the resist pattern 23,
the first metal layer 12 and the second metal layer 18 are
patterned.
[0046] In FIG. 3A and FIG. 3B, since the thick metal layer formed
of the first metal layer 12 and the second metal layer 18 on the
substrate 11 needs to be etched together, it takes a long time with
the current dry-etching technique, so that a load of the etching
process is increased. As a result, it is difficult to form the
first metal layer 12 and the second metal layer 18 which are
patterned accurately.
[0047] In contrast, in accordance with the example embodiment, a
load of the etching process can be reduced, and it is possible to
obtain the first metal layer 12 and the second metal layer 18 which
are patterned accurately.
[0048] Further, in the present example embodiment, the second metal
layer 18 is used as a mask for etching the substrate 11. However,
the example embodiment is not limited thereto, and the second metal
layer 18 may be used as a wiring of a device by being formed to
have a required thickness.
[0049] From the foregoing, it will be appreciated that various
embodiments of the present disclosure have been described herein
for purposes of illustration, and that various modifications may be
made without departing from the scope and spirit of the present
disclosure. Accordingly, the various embodiments disclosed herein
are not intended to be limiting, with the true scope and spirit
being indicated by the following claims.
* * * * *