U.S. patent application number 14/404174 was filed with the patent office on 2015-06-18 for plating apparatus, plating method, 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 | 20150167174 14/404174 |
Document ID | / |
Family ID | 49673257 |
Filed Date | 2015-06-18 |
United States Patent
Application |
20150167174 |
Kind Code |
A1 |
Mizutani; Nobutaka ; et
al. |
June 18, 2015 |
PLATING APPARATUS, PLATING METHOD, AND STORAGE MEDIUM
Abstract
A plating method can improve uniformity in thickness of a
plating layer formed on an inner surface of a recess. The plating
method includes a loading process of loading the substrate in which
the recess is formed into a casing; and a plating process of
supplying a plating liquid to the substrate and forming a plating
layer having a specific function on an inner surface of the recess.
In the plating process, after supplying the plating liquid to the
substrate and filling the plating liquid into the recess, a plating
liquid having a higher temperature than a temperature of the
plating liquid is supplied to the substrate.
Inventors: |
Mizutani; Nobutaka;
(Nirasaki-shi, JP) ; Tanaka; Takashi;
(Nirasaki-shi, JP) ; Iwashita; Mitsuaki;
(Nirasaki-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tokyo Electron Limited |
Tokyo |
|
JP |
|
|
Family ID: |
49673257 |
Appl. No.: |
14/404174 |
Filed: |
May 27, 2013 |
PCT Filed: |
May 27, 2013 |
PCT NO: |
PCT/JP2013/064644 |
371 Date: |
November 26, 2014 |
Current U.S.
Class: |
427/299 ;
118/697; 118/73 |
Current CPC
Class: |
H01L 21/76898 20130101;
H01L 21/76843 20130101; H01L 21/288 20130101; C23C 18/1676
20130101; C23C 18/1619 20130101; C23C 18/168 20130101; C23C 18/1875
20130101; C23C 18/1616 20130101 |
International
Class: |
C23C 18/18 20060101
C23C018/18; C23C 18/16 20060101 C23C018/16 |
Foreign Application Data
Date |
Code |
Application Number |
May 30, 2012 |
JP |
2012-123611 |
Claims
1. A plating method of performing a plating process to a recess
formed in a substrate, the plating method comprising: a loading
process of loading the substrate in which the recess is formed into
a casing; and a plating process of supplying a plating liquid to
the substrate and forming a plating layer having a specific
function on an inner surface of the recess, wherein, in the plating
process, after supplying the plating liquid to the substrate and
filling the plating liquid into the recess, a plating liquid having
a higher temperature than a temperature of the plating liquid is
supplied to the substrate.
2. The plating method of claim 1, further comprising: a
pre-treatment process of supplying a pre-treatment liquid to the
substrate, wherein the plating process includes a substation
process of supplying the plating liquid to the substrate and
substituting the pre-treatment liquid filled into the recess in the
substrate with the plating liquid, and a film forming process of
forming the plating layer by supplying the plating liquid to the
substrate after the substitution process, and a temperature of the
plating liquid used in the substitution process is set to be lower
than a temperature of the plating liquid used in the film forming
process.
3. The plating method of claim 2, wherein the film forming process
includes a process of supplying a plating liquid heated to a
temperature higher than the temperature of the plating liquid used
in the substitution process to the substrate.
4. The plating method of claim 2, wherein the film forming process
includes a process of heating the plating liquid supplied to the
substrate to a temperature higher than the temperature of the
plating liquid used in the substitution process.
5. The plating method of claim 2, wherein the pre-treatment liquid
is formed of deionized water on which a deaeration process is
performed.
6. The plating method of claim 5, further comprising: a pre-wet
process of supplying ionized water containing ions to the substrate
before the pre-treatment process.
7. The plating method of claim 2, wherein, in the film forming
process, the plating liquid is discharged from multiple discharge
nozzles arranged in parallel with each other along a radial
direction of the substrate or discharged from a discharge nozzle
extended along the radial direction of the substrate.
8. A plating apparatus of performing a plating process to a recess
formed in a substrate, the plating apparatus comprising: a
substrate holding unit configured to hold the substrate in which
the recess is formed; and a plating unit configured to supply a
plating liquid to the substrate and form a plating layer having a
specific function on an inner surface of the recess, wherein, after
supplying the plating liquid to the substrate and filling the
plating liquid into the recess, the plating unit is configured to
supply a plating liquid having a higher temperature than a
temperature of the plating liquid.
9. The plating apparatus of claim 8, further comprising: a
pre-treatment unit configured to supply a pre-treatment liquid to
the substrate, wherein the plating unit includes a substitution
unit configured to supply the plating liquid for substituting the
pre-treatment liquid filled into the recess in the substrate to the
substrate, and a film forming unit configured to supply the plating
liquid to the substrate after the substitution unit supplies the
plating liquid to the substrate, and a temperature of the plating
liquid used in the substitution unit is set to be lower than a
temperature of the plating liquid used in the film forming
unit.
10. The plating apparatus of claim 9, wherein the film forming unit
is configured to supply a plating liquid heated to a temperature
higher than the temperature of the plating liquid used in the
substitution unit to the substrate.
11. The plating apparatus of claim 9, wherein the film forming unit
is configured to heat the plating liquid supplied to the substrate
to a temperature higher than the temperature of the plating liquid
used in the substitution unit.
12. The plating apparatus of claim 9, wherein the pre-treatment
liquid is formed of deionized water on which a deaeration process
is performed.
13. The plating apparatus of claim 12, further comprising: a
pre-wet unit configured to supply ionized water containing ions to
the substrate before supplying the pre-treatment liquid to the
substrate.
14. The plating apparatus of claim 9, wherein the film forming unit
includes multiple discharge nozzles arranged in parallel with each
other along a radial direction of the substrate and configured to
discharge the plating liquid to the substrate, or a discharge
nozzle extended along the radial direction of the substrate and
configured to discharge the plating liquid to the substrate.
15. A computer-readable storage medium having stored thereon
computer-executable instructions that, in response to execution,
cause a plating apparatus to perform a plating method of performing
a plating process to a recess formed in a substrate, wherein the
plating method comprises: a loading process of loading the
substrate in which the recess is formed into a casing; and a
plating process of supplying a plating liquid to the substrate and
forming a plating layer having a specific function on an inner
surface of the recess, wherein, in the plating process, after
supplying the plating liquid to the substrate and filling the
plating liquid into the recess, a plating liquid having a higher
temperature than a temperature of the plating liquid is supplied to
the substrate.
Description
TECHNICAL FIELD
[0001] The embodiments described herein pertain generally to a
plating method of performing a plating process to a recess formed
in a substrate, a plating apparatus, and a storage medium.
BACKGROUND
[0002] In general, there is formed a circuit wiring on a substrate
such as a semiconductor wafer or a liquid crystal substrate for
forming a semiconductor device. As a method of forming a wiring,
there has been used a damascene method in which a recess such as a
via or a trench for burying a wiring material such as copper is
formed in the substrate and the wiring material is buried in the
recess.
[0003] Further, in recent years, there has been made an attempt to
reduce a mounting area of a part or a whole system by mounting
multiple LSIs on a substrate using a three-dimensional mounting
technology. In the three-dimensional mounting technology, a recess,
e.g., a through-silicon-via (TSV), for burying a wiring material,
which connects the LSIs, is formed, for example, in a substrate
(e.g., a silicon substrate).
[0004] Between an inner surface of a recess in a substrate and a
wiring formed in the recess, typically, there is formed a barrier
film for suppressing diffusion of atoms constituting a wiring
material into an insulting film (an oxide film, PI "polyimide",
etc.) on the inner surface of the recess and into the substrate on
a rear surface side thereof, or for improving adhesivity
therebetween. Further, between the barrier film and the wiring,
typically, there is formed a seed film for making it easy to bury
the wiring material.
[0005] By way of example, in Patent Document 1, there is suggested
a method in which a barrier film containing ruthenium is formed on
an inner surface of a recess by sputtering, a seed film containing
ruthenium and copper is formed on the barrier film by sputtering,
and then, copper is buried in the recess by a plating process.
REFERENCES
[0006] Patent Document 1: Japanese Patent Laid-open Publication No.
2010-177538
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0007] In recent years, there has been developed a manufacturing
technique employing a TSV. In this manufacturing technique, a
height or a depth of a recess in the TSV is not in a range of
several tens of nanometers to several hundreds of nanometers in a
conventional pre-treatment process but in a range of several
microns to several hundreds of microns. For this reason, the
conventional manufacturing technique may be employed in some cases,
but a different method may be needed in some cases.
[0008] By way of example, a sputtering method which has been
typically used for forming a barrier film or a seed film has a high
directionality. For this reason, if a recess has a great height or
depth, it is difficult to sufficiently form a barrier film or a
seed film on a lower portion of the recess.
[0009] In order to solve such problems, a plating method such as an
electroplating process or an electroless plating process may be
considered. However, if a recess has a small diameter and a great
height or depth, a plating liquid within the recess has a low
fluidity, which may cause nonuniformity in concentration
distribution of the plating liquid between an upper portion of the
recess and a lower portion thereof. If there is nonuniformity in
the concentration distribution of the plating liquid within the
recess, it can be assumed that there is nonuniformity in
distribution of density or a thickness of a plating layer such as a
barrier film or a seed film formed on an inner surface of the
recess.
[0010] In view of the foregoing problems, example embodiments
provide a plating method capable of improving uniformity in
thickness of a plating layer formed on an inner surface of a
recess, a plating apparatus, and a storage medium.
Means for Solving the Problems
[0011] In accordance with a first aspect, a plating method of
performing a plating process to a recess formed in a substrate
includes a loading process of loading the substrate in which the
recess is formed into a casing; and a plating process of supplying
a plating liquid to the substrate and forming a plating layer
having a specific function on an inner surface of the recess. In
the plating process, after supplying the plating liquid to the
substrate and filling the plating liquid into the recess, a plating
liquid having a higher temperature than a temperature of the
plating liquid is supplied to the substrate.
[0012] In accordance with a second aspect, a plating apparatus of
performing a plating process to a recess formed in a substrate
includes a substrate holding unit configured to hold the substrate
in which the recess is formed; and a plating unit configured to
supply a plating liquid to the substrate and form a plating layer
having a specific function on an inner surface of the recess. After
supplying the plating liquid to the substrate and filling the
plating liquid into the recess, the plating unit is configured to
supply a plating liquid having a higher temperature than a
temperature of the plating liquid.
[0013] In accordance with a third aspect, a computer-readable
storage medium has stored thereon computer-executable instructions
that, in response to execution, cause a plating apparatus to
perform a plating method of performing a plating process to a
recess formed in a substrate. The plating method includes a loading
process of loading the substrate in which the recess is formed into
a casing; and a plating process of supplying a plating liquid to
the substrate and forming a plating layer having a specific
function on an inner surface of the recess and in the plating
process, after supplying the plating liquid to the substrate and
filling the plating liquid into the recess, a plating liquid having
a higher temperature than a temperature of the plating liquid is
supplied to the substrate.
Effect of the Invention
[0014] In accordance with the example embodiments, it is possible
to improve uniformity in distribution of density or a thickness of
a plating layer formed on an inner surface of a recess.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a side view illustrating a plating apparatus in
accordance with one example embodiment.
[0016] FIG. 2A and FIG. 2B are plane views of the plating apparatus
illustrated in FIG. 1.
[0017] FIG. 3 is a diagram illustrating a film forming plating
liquid supply unit configured to supply a high-temperature plating
liquid to a film forming unit of a plating unit.
[0018] FIG. 4 is a diagram illustrating a substitution plating
liquid supply unit configured to supply a low-temperature plating
liquid to a substitution unit of the plating unit.
[0019] FIG. 5 is a flowchart showing a plating method.
[0020] FIG. 6A is a diagram illustrating a process of preparing a
substrate in which a recess is formed.
[0021] FIG. 6B is a diagram illustrating a process of supplying a
pre-treatment liquid into the recess.
[0022] FIG. 6C is a diagram illustrating a substitution process of
substituting the pre-treatment liquid filled in the recess of the
substrate with a low-temperature plating liquid.
[0023] FIG. 6D is a diagram illustrating a film forming process of
supplying a high-temperature plating liquid to a substrate.
[0024] FIG. 6E is a diagram illustrating that a plating layer is
formed on an inner surface of the recess.
[0025] FIG. 6F is a diagram illustrating a process of burying a
wiring material in the recess.
[0026] FIG. 7 is a diagram illustrating that the pre-treatment
liquid is substituted with the low-temperature plating liquid.
[0027] FIG. 8 is a diagram illustrating that multiple discharge
nozzles of the film forming unit are supplying a plating liquid to
the substrate.
[0028] FIG. 9 illustrates a modification example of the plating
liquid supply unit.
[0029] FIG. 10 illustrates a modification example of the
substitution unit.
[0030] FIG. 11 is a diagram illustrating a relationship between a
diffusion time and a diffusion distance when components of the
plating liquid are diffused in the substitution process.
[0031] FIG. 12 illustrates an example of a plating layer formed in
an experimental example 1.
[0032] FIG. 13 illustrates an example of a plating layer formed in
a comparative example 1.
MODE FOR CARRYING OUT THE INVENTION
[0033] Hereinafter, referring to FIG. 1 to FIG. 8, the example
embodiments will be explained. Referring to FIG. 1, FIG. 2A and
FIG. 2B, an overall configuration of a plating apparatus 20 will be
explained first. FIG. 1 is a side view illustrating the plating
apparatus 20, and FIG. 2A and FIG. 2B are plane views of the
plating apparatus 20. Further, in the present example embodiment,
there will be explained an example where the plating apparatus 20
is a single-substrate processing apparatus that performs a plating
process to a single substrate 2 by discharging a plating liquid to
the substrate 2.
[0034] Plating Apparatus
[0035] The plating apparatus 20 includes a substrate holding unit
110 configured to hold and rotate a substrate 2 within a casing
101; a plating unit 30 configured to discharge a plating liquid
toward the substrate 2 held by the substrate holding unit 110 and
form a plating layer having a specific function on an inner surface
of a recess in the substrate; and a plating liquid supply unit
connected to the plating unit 30 and configured to supply the
plating liquid to the plating unit 30. The plating unit 30 includes
a substitution unit 55 configured to discharge a low-temperature
plating liquid toward the substrate 2; and a film forming unit 35
configured to discharge a high-temperature plating liquid, which
has a temperature higher than that of the plating liquid discharged
from the substitution unit 55, toward the substrate 2. Further, the
term "low temperature" means that a plating reaction cannot proceed
actively at the temperature of the plating liquid discharged from
the substitution unit 55. By way of example, it means that a film
forming rate of a plating layer formed of the plating liquid
discharged from the substitution unit 55 has 10% or less of a film
forming rate of a plating layer 15 finally formed of the
high-temperature plating liquid. Further, the term "high
temperature" means that a plating process can be completed within
an allowable processing time at the temperature of the plating
liquid discharged from the film forming unit 35.
[0036] Further, the plating liquid supply unit includes a film
forming plating liquid supply unit 71 configured to supply the
high-temperature plating liquid to the film forming unit 35 and a
substitution plating liquid supply unit 74 configured to supply the
low-temperature plating liquid to the substitution unit 55.
[0037] Furthermore, the plating apparatus 20 further includes a
pre-treatment unit 54 configured to discharge a pre-treatment
liquid toward the substrate 2. The pre-treatment unit 54 is
connected to a pre-treatment liquid supply unit 73 configured to
supply the pre-treatment liquid to the pre-treatment unit 54. The
pre-treatment liquid is a liquid to be discharged toward the
substrate 2 before the plating liquid is discharged toward the
substrate 2. As the pre-treatment liquid, for example, deionized
pure water, so-called deionized water (DIW), may be used.
[0038] Moreover, the plating apparatus 20 may further include a
pre-wet unit 57 configured to discharge a pre-wet liquid toward the
substrate 2. The pre-wet unit 57 is connected to a pre-wet liquid
supply unit 76 configured to supply the pre-wet liquid to the
pre-wet unit 57. The pre-wet liquid is a liquid to be supplied
toward the substrate 2 in a dry state. With the pre-wet liquid, for
example, affinity between a processing liquid to be subsequently
supplied toward the substrate 2 and the substrate 2 can be
increased. As the pre-wet liquid, ionized water containing ions of
CO.sub.2 may be used.
[0039] Around the substrate holding unit 110, a liquid drain cup
120 including a first opening portion 121 and a second opening
portion 126 and configured to receive a liquid such as the plating
liquid or the pre-treatment liquid scattered from the substrate 2
and an exhaust cup 105 including an opening portion 106 for sucking
a gas are arranged. Liquids received by the first opening portion
121 and the second opening portion 126 of the liquid drain cup 120
are drained out by a first liquid drain unit 122 and a second
liquid drain unit 127, respectively. A gas sucked from the opening
portion 106 of the exhaust cup 105 is exhausted by an exhaust unit
107. Further, the liquid drain cup 120 is connected to an elevation
unit 164, and the elevation unit 164 can move the liquid drain cup
120 up and down. For this reason, the liquid drain cup 120 can be
moved up and down according to a kind of a liquid scattered from
the substrate 2, so that a path through which the liquid is drained
out can be different for each kind of a liquid.
[0040] (Substrate Holding Unit)
[0041] As depicted in FIG. 2A and FIG. 2B, the substrate holding
unit 110 includes a hollow cylindrical rotation shaft 111
vertically extended within the casing 101; a turn table 112
provided at an upper end of the rotation shaft 111; a wafer chuck
113 provided at an outer periphery of an upper surface of the turn
table 112 and configured to support the substrate 2; and a rotation
unit 162 connected to the rotation shaft 111 and configured to
rotate and drive the rotation shaft 111.
[0042] The rotation unit 162 is controlled by a control unit 160 to
rotate and drive the rotation shaft 111. Thus, the substrate 2
supported by the wafer chuck 113 is rotated. In this case, the
control unit 160 controls the rotation unit 162, so that the
rotation shaft 111 and the wafer chuck 113 can be rotated or the
rotation thereof can be stopped. Further, the control unit 160 can
increase or decrease the rotation number of the rotation shaft 111
and the wafer chuck 113, or can control the rotation number to be
maintained at a certain value.
[0043] (Plating Unit)
[0044] Hereinafter, the film forming unit 35 and the substitution
unit 55 of the plating unit 30 will be explained. The film forming
unit 35 will be explained first. The film forming unit 35 includes
a discharge nozzle 34 configured to discharge the plating liquid
toward the substrate 2 and a discharge head 33 in which the
discharge nozzle 34 is provided. Within the discharge head 33, a
line through which the plating liquid supplied from the plating
liquid supply unit 71 is introduced to the discharge nozzle 34 and
a line through which a heat transfer medium for keeping heat of the
plating liquid is circulated are accommodated.
[0045] The discharge head 33 is configured to be vertically and
horizontally moved. By way of example, the discharge head 33 is
provided at a front end of an arm 32, and the arm 32 is fixed at a
supporting shaft 31 which can be vertically extended and can be
rotated by a rotation unit 165. As depicted in FIG. 2A, with the
rotation unit 165 and the supporting shaft 31, the discharge head
33 can be moved between a discharge position where the discharge
head 33 discharges the plating liquid toward the substrate 2 and a
stand-by position where the discharge head 33 does not discharge
the plating liquid.
[0046] As depicted in FIG. 1, the discharge head 33 may be extended
to have a length corresponding to a length from a central portion
of the substrate 2 to a peripheral portion of the substrate 2,
i.e., the radius of the substrate 2. In this case, in the discharge
head 33, there may be provided multiple discharge nozzles 34
configured to discharge the plating liquid. In this case, when the
plating liquid is discharged, the discharge head 33 is positioned
such that the multiple discharge nozzles 34 are arranged along a
radial direction of the substrate 2, and, thus, it is possible to
supply the plating liquid throughout a wide area of the substrate 2
at the same time. Further, although not illustrated, the discharge
nozzles 34 provided in the discharge head 33 may be extended along
the radial direction of the substrate 2 and configured to discharge
the plating liquid toward the substrate 2. Even in this case, it is
possible to supply the plating liquid throughout a wide area of the
substrate 2 at the same time.
[0047] Hereinafter, the substitution unit 55 will be explained. As
depicted in FIG. 1, the first substitution unit 55 includes a
discharge nozzle 55a configured to discharge the plating liquid
toward the substrate 2; and a discharge head 53 in which the
discharge nozzle 55a is provided. The discharge head 53 is
configured to be vertically and horizontally moved. By way of
example, the discharge head 53 of the substitution unit 55 is
provided at a front end of an arm 52 in the same manner as the
discharge head 33 of the film forming unit 35. The arm 52 is fixed
at a supporting shaft 51 which can be vertically extended and can
be rotated by a rotation unit 166. In this case, as depicted in
FIG. 2B, the discharge head 53 can be horizontally rotated about an
axis of the supporting shaft 51 between a position corresponding to
the central portion of the substrate 2 and a position corresponding
to the peripheral portion of the substrate 2.
[0048] (Plating Liquid Supply Unit)
[0049] Hereinafter, referring to FIG. 3, there will be explained
the film forming plating liquid supply unit 71 and the substitution
plating liquid supply unit 74 of the plating liquid supply unit
respectively configured to supply the plating liquid to the film
forming unit 35 and the substitution unit 55 of the plating unit
30. Further, the film forming plating liquid supply unit 71 and the
substitution plating liquid supply unit 74 are different from each
other only in whether or not a heating unit configured to heat the
plating liquid is provided and have the same configuration except
such a difference. Herein, the film forming plating liquid supply
unit 71 will be mainly explained.
[0050] As depicted in FIG. 3, the plating liquid supply unit 71
includes a tank 71b configured to store and preserve therein a
plating liquid 71c; and a supply line 71a through which the plating
liquid 71c stored within the tank 71b is supplied to the plating
unit 30. The supply line 71a includes a pump 71e and a valve 71d
for controlling a flow rate of the plating liquid 71c. Further, at
the tank 71b, there is provided a heating unit 71g configured to
heat the plating liquid 71c stored in the tank 71b.
[0051] (Plating Liquid)
[0052] Hereinafter, the plating liquid used in the present example
embodiment will be explained. Further, a plating liquid to be
supplied from the film forming plating liquid supply unit 71 to the
film forming unit 35 and a plating liquid to be supplied from the
substitution plating liquid supply unit 74 to the substitution unit
5 are substantially the same except a temperature thereof.
Hereinafter, the term "plating liquid" to be used when explaining a
material or a component of the plating liquid refers to both of the
plating liquid to be used in the film forming unit 35 and the
plating liquid to be used in the substitution unit 55.
[0053] The plating liquid contains a material corresponding to the
plating layer formed on the surface of the substrate 2 and having a
specific function. By way of example, if the plating layer formed
on the substrate 2 by the plating apparatus 20 serves as a barrier
film that suppresses permeation of a metal material constituting a
wiring into an insulating film or the substrate 2, the plating
liquid contains Co (cobalt), W (tungsten), or Ta (tantalum) to be
used as a material of the barrier film. Further, if the plating
layer formed on the substrate 2 by the plating apparatus 20 serves
as a seed film configured to allow a wiring material, the plating
liquid contains Cu (copper) to be used as a wiring material to be
easily buried. In addition, the plating liquid may contain a
complexing agent, or a reducing agent (a compound containing B
(boron) and P (phosphor)), and a surfactant depending on a material
contained therein or a kind of a plating reaction.
[0054] Further, the plating liquid may contain an additive which
can affect a plating reaction rate. The additive can be
appropriately selected depending on materials contained in the
plating liquid. By way of example, if the plating liquid contains
Co and W to be used as a material of the barrier film, the plating
liquid contains bis (3-sulfopropyl) disulfide, so-called SPS, as
the additive.
[0055] (Pre-Treatment Unit and Pre-Wet Unit)
[0056] Hereinafter, the pre-treatment unit 54 and the pre-wet unit
57 will be explained. The pre-treatment unit 54 includes a
discharge nozzle 54a configured to discharge a pre-treatment liquid
toward the substrate 2. In the same manner, the pre-wet unit
includes a discharge nozzle 57a configured to discharge a pre-wet
liquid toward the substrate 2. As depicted in FIG. 1, each of the
discharge nozzles 54a and 57a may be provided in the
above-described discharge head 53 that can be vertically and
horizontally moved.
[0057] (Pre-Treatment Liquid Supply Unit and Pre-Wet Liquid Supply
Unit)
[0058] Hereinafter, referring to FIG. 4, there will be explained
the pre-treatment liquid supply unit 73 configured to supply the
pre-treatment liquid to the pre-treatment unit 54 and a pre-wet
liquid supply unit 76 configured to supply the pre-wet liquid
toward the pre-wet unit 57. Further, the pre-treatment liquid
supply unit 73 and the pre-wet liquid supply unit 76 are different
from each other only in a kind of a processing liquid and have the
same configuration except such a difference. Herein, the
pre-treatment liquid supply unit 73 will be mainly explained.
[0059] As depicted in FIG. 4, the pre-treatment liquid supply unit
73 includes a tank 73b configured to store a pre-treatment liquid
73c such as DIW; and a supply line 73a configured to supply the
pre-treatment liquid 73c stored within the tank 73b to the
pre-treatment unit 54. The supply line 73a includes a pump 73e and
a valve 73d for regulating a flow rate of the pre-treatment liquid
73c.
[0060] Further, the pre-treatment liquid supply unit 73 may further
include a deaeration device 73f configured to remove a gas such as
dissolved oxygen or dissolved hydrogen in the pre-treatment liquid
73c. As depicted in FIG. 4, the deaeration device 73f may be
configured as a gas supply line for supplying an inert gas such as
nitrogen to the pre-treatment liquid 73c stored in the tank 73b.
Thus, the inert gas can be dissolved in the pre-treatment liquid
73c, so that oxygen or hydrogen already dissolved in the
pre-treatment liquid 73c can be discharged to the outside. That is,
a deaeration process can be performed on the pre-treatment liquid
73c. A degree of the deaeration process performed by the deaeration
device 73f is not particularly limited. However, for example, the
deaeration process may be performed such that an oxygen
concentration in the cleaning liquid 73c to be discharged toward
the substrate 2 is 1 ppm or less, and desirably, 0.5 ppm or
less.
[0061] The plating apparatus 20 configured as described above is
controlled by a control unit 160 according to various programs
recorded in a storage medium 161 provided in the control unit 160.
Thus, various processes are performed to the substrate 2. Herein,
the storage medium 161 stores various setting data or various
programs such as a plating process program to be described later.
As the storage medium 161, a publicly known storage medium such as
a computer-readable memory, e.g., a ROM or a RAM, or a hard disc, a
disc-shaped storage medium, e.g., a CD-ROM, a DVD-ROM, or a
flexible disc may be used.
[0062] Plating Method
[0063] Hereinafter, an operation and an effect of the present
example embodiment configured as described above will be explained.
There will be explained a plating method of forming a barrier film
of CoWB by an electroless plating process on an inner surface of
the recess 12 formed in the substrate 2. FIG. 5 is a flowchart
showing the plating method. Further, FIG. 6A to FIG. 6F are
cross-sectional views illustrating the substrate 2 in the
respective processes of the plating method.
[0064] Firstly, the recess 12 for burying a wiring material is
formed in the substrate 2. As a method of forming the recess 12 in
the substrate 2, one of the conventionally known methods may be
appropriately employed. To be specific, for example, as a dry
etching technique, a general-purpose technique using a
fluorine-based or chlorine-based gas may be employed. In
particular, in order to form the recess 12 having a high aspect
ratio (ratio of a depth of a hole to a diameter thereof), a method
using an ICP-RIE (Inductively Coupled Plasma Reactive Ion Etching)
technique capable of deep-etching at a high speed may be employed
more appropriately. In particular, a so-called Bosch process in
which an etching process using a sulphur hexafluoride (SF.sub.6)
and a protection process using a Teflon-based gas such as
C.sub.4F.sub.8 are repeatedly performed may be appropriately
employed.
[0065] A shape of the recess 12 is not particularly limited as long
as a movement of each component of the plating liquid within the
recess 12 is based on mainly the diffusion instead of on the flow.
By way of example, an aspect ratio of the recess 12 is in a range
of 5 to 30. To be specific, if a horizontal cross section of the
recess has a circular shape, a diameter of the recess 12 is in a
range of 0.5 .mu.m to 20 .mu.m, for example, 8 .mu.m. Further, a
height or depth of the recess 12 is in a range of 10 .mu.m to 250
.mu.m, for example, 100 .mu.m. Then, an insulating film is formed
within the recess 12. As a method of forming the insulating film,
for example, a method of forming a silicon oxide film (SiO.sub.2)
by a CVD (Chemical Vapor Deposition) method is used.
[0066] Then, the substrate 2 is prepared within the casing 101. In
the pre-wet unit 57, a pre-wet liquid 76c is discharged toward the
substrate 2 (Pre-wet process (S10)). Thus, as depicted in FIG. 6A,
the surface of the substrate 2, for example, the inner surface 12a
of the recess 12 and the upper surface of the substrate 2, may be
brought into contact with the pre-wet liquid 76c. Thus, the
affinity between the surface of the substrate 2 and the
pre-treatment liquid to be supplied to the substrate 2 can be
increased. As the pre-wet liquid 76c, for example, ionized water
containing ions of CO.sub.2 may be used.
[0067] Then, in the pre-treatment unit 54, the pre-treatment liquid
73c is discharged toward the substrate 2 (Pre-treatment process
(S20)). Thus, as depicted in FIG. 6B, the inside of the recess 12
is filled with the pre-treatment liquid 73c. As the pre-treatment
liquid 73c, for example, DIW on which a deaeration process is
performed may be used.
[0068] Thereafter, in the plating unit 30, the plating liquid 71c
for forming a film of CoWB is discharged toward the substrate 2
(Plating process (S21)). The plating process (S21), as depicted in
FIG. 5, includes a substitution process (S21a) of discharging a
low-temperature plating liquid 74c toward the substrate 2 and a
film forming process (S21b) of discharging a high-temperature
plating liquid 71c toward the substrate 2.
[0069] In the substitution process (S21a), substitution plating
liquid supply unit 74 supplies the low-temperature plating liquid
74c to the substitution unit 55. The supplied plating liquid 74c
has a temperature, for example, a room temperature (25.degree. C.),
at which a plating reaction cannot proceed actively. Then, the
plating liquid 74c is discharged toward the substrate 2 from the
discharge nozzle 55a provided in the discharge head 53.
[0070] As described above, the recess 12 formed in the substrate 2
has a high aspect ratio. Further, a depth of the recess 12 is
remarkably increased as compared with a depth of the conventional
recess, and it is, for example, 100 .mu.m. If the plating liquid
74c is supplied into the deep recess 12, each component contained
in the plating liquid 74c reaches to the bottom of the recess 12
based on mainly the diffusion in the plating liquid. Meanwhile,
diffusion is a phenomenon that gradually proceeds as times passes.
For this reason, each component of the plating liquid 74c takes a
preset time to sufficiently reach to the bottom of the recess 12.
Therefore, the substitution process (S21a) of supplying the plating
liquid 74c toward the substrate 2 is continuously performed for a
preset time to sufficiently substitute the pre-treatment liquid 73c
within the recess 12 with the plating liquid 74c.
[0071] Hereinafter, there will be explained an example of a method
for determining a continuation time of the substitution process
(S21a).
[0072] Generally, abnormal diffusion in a plating liquid can be
represented by the Fick's second law of diffusion as follows:
.differential. C .differential. t = D .differential. 2 C
.differential. x 2 [ Equation 1 ] ##EQU00001##
[0073] Herein, D is a diffusion coefficient of a component to be
diffused; C is a concentration of the component to be diffused; t
is a time; and x is a distance from a reference position. A
relationship between a diffusion time and a diffusion distance when
a plating component (a component of a material constituting a
plating layer) in a plating liquid is calculated based on the
Fick's second law of diffusion and a result thereof is as shown in
FIG. 11. In FIG. 11, the horizontal axis represents a time, and the
longitudinal axis represents a distance from an upper end of the
recess 12. Further, the calculation is carried out on the
presumption that in the case of time (t)=0, the inside of the
recess 12 is filled with the pre-treatment liquid 73c only, and in
the case of time (t)=0, the liquid present above the upper end of
the recess 12 is substituted with the plating liquid 74c.
Furthermore, a depth of the recess 12 is presumed infinite.
Further, in FIG. 11, the solid line or the dashed lines annotated
as "x % (x=50, 65, 80, 88, or 95)" represent a diffusion time
required for a concentration of a plating component at a
corresponding distance to reach x % of a concentration of a plating
component at the upper end of the recess 12. By way of example, in
FIG. 11, the dot with symbol A means a diffusion time of 600
seconds which is required for a concentration of a plating
component at a position 70 .mu.m away from the upper end of the
recess 12 to reach 95% of a concentration of a plating component at
the upper end of the recess 12.
[0074] Based on the relationship as shown in FIG. 11, a
continuation time of the substitution process (S21a) can be
determined. By way of example, as for the recess 12 having a depth
of 100 .mu.m, if a concentration of a plating component at the
bottom of the recess 12 is required to reach about 90% of a
concentration of a plating component of the plating liquid 74c
supplied to the substrate 2, a continuation time of the
substitution process (S21a) is set to about 600 seconds. Since the
substitution process (S21a) is continued for such a long time, the
plating liquid 74c can sufficiently reach to the bottom of the
recess 12. Thus, a concentration distribution of the plating liquid
74c filled in the recess 12 can be substantially uniform.
[0075] Further, in the present example embodiment, as described
above, the temperature of the plating liquid 74c to be supplied to
the substrate 2 in the substitution process (S21a) is set to a low
level at which a plating reaction cannot proceed actively. By way
of example, the temperature of the plating liquid 74c is set such
that a film forming rate of a plating layer formed during the
substitution process (S21a) has 10% or less of a film forming rate
of the plating layer 15 finally formed of the high-temperature
plating liquid. For this reason, it is possible to suppress
significant progress of a plating reaction before the plating
liquid 74 sufficiently reaches to the bottom of the recess 12.
[0076] Then, the film forming unit 35 discharges a high-temperature
plating liquid 71c toward the substrate 2 (Film forming process
(S21b)). To be specific, the film forming plating liquid supply
unit 71 supplies the plating liquid 71c heated to a high
temperature to the film forming unit 35. The supplied plating
liquid 71c has a temperature, for example, 45.degree. C., at which
a plating reaction can proceed at an appropriate rate. Then, as
depicted in FIG. 8, the plating liquid 71c is discharged toward the
substrate 2 from the multiple discharge nozzles 34 arranged in
parallel with each other along the radial direction of the
substrate 2. Thus, it is possible to supply the plating liquid 71c
throughout a wide area of the substrate 2 at the same time. Thus, a
temperature distribution of the plating liquid 71c on the substrate
2 can be substantially uniform regardless of positions on the
substrate 2. By way of example, a temperature of the plating liquid
71c reaching a central portion of the substrate 2 can be
substantially equal to a temperature of the plating liquid 71c
reaching a peripheral portion of the substrate 2.
[0077] When the film forming process (S21b) is started, as
described above, the low-temperature plating liquid 74c has been
already filled in the recess 12l In this case, if the
high-temperature plating liquid 71c is supplied to the substrate 2,
above the upper end of the recess 12, i.e., above an upper surface
11a of an insulating layer 11, the low-temperature plating liquid
74c is substituted with the high-temperature plating liquid 71c.
Then, the low-temperature plating liquid 74c filled in the recess
12 is heated by heat from the high-temperature plating liquid 71c.
Herein, generally, a velocity of thermal conduction in a liquid is
higher than a velocity of diffusion of the component in the liquid.
For this reason, the low-temperature plating liquid 74c within the
recess 12 is rapidly heated to be changed into the high-temperature
plating liquid 71c. That is, the inside of the recess 12 can be
rapidly filled with the high-temperature plating liquid 71c.
Further, although the plating liquid 74c and the plating liquid 71c
are assigned different reference numerals, they are substantially
the same except the temperature thereof as described above.
Therefore, by heating the low-temperature plating liquid 74c, it is
possible to substitute or change the low-temperature plating liquid
74c into the high-temperature plating liquid 71c.
[0078] When the inside of the recess 12 is filled with the
high-temperature plating liquid 71c, as depicted in FIG. 6E, the
plating layer 15 is formed on the inner surface 12a of the recess
12. Herein, as described above, the high-temperature plating liquid
71c within the recess 12 is obtained by heating the low-temperature
plating liquid 74c having a substantially uniform concentration
distribution within the recess 12. For this reason, in accordance
with the present example embodiment, a concentration distribution
of the plating liquid 71c within the recess 12 can be uniform as
compared with the case where the substitution process is not
performed in advance. Thus, the plating reaction in the film
forming process (S21b) can be started with the plating liquid 71c
having a substantially uniform concentration distribution
regardless of the positions within the recess 12. Accordingly,
uniformity in thickness or density distribution of the plating
layer 15 formed on the inner surface 12a of the recess 12 can be
increased.
[0079] Then, post-treatments including rinsing processes (S32 and
S40) of discharging a rinse liquid toward the substrate 2, a
post-cleaning process (S33) of discharging a post-cleaning liquid
toward the substrate 2, and a drying process (S41) of drying the
substrate 2 with air or IPA are carried out. As such, the substrate
2 on which the barrier film of the plating layer 15 is formed can
be obtained.
[0080] Then, as depicted in FIG. 6F, a seed film 16 may be formed
on the barrier film of the plating layer 15. Further, a wiring 17
including a metal material such as copper may be formed within the
recess 12 covered with the seed film 16. A method of forming the
seed film 16 and the wiring 17 is not particularly limited, but,
for example, an electroless plating method may be used. Herein, in
the same manner as the case of forming the barrier film of the
plating layer 15, a two plating processes using two kinds of
plating liquids different in the temperature may be performed.
[0081] In accordance with the present example embodiment, as
described above, the plating process (S21) includes the
substitution process (S21a) using the low-temperature plating
liquid 74c and the film forming process (S21b) using the
high-temperature plating liquid 71c. Since the plating process
divided into the two processes is performed as such, when a plating
reaction is carried out with the high-temperature plating liquid
71c, a concentration distribution of the high-temperature plating
liquid 71c within the recess 12 can be substantially uniform
regardless of the positions within the recess 12. Thus, uniformity
in thickness or density distribution of the plating layer 15 formed
on the recess 12 can be increased.
[0082] Further, in accordance with the present example embodiment,
as described above, the DIW on which a deaeration process is
performed is used as the pre-treatment liquid 73c to be supplied to
the substrate 2 in the pre-treatment process (S20). For this
reason, it is possible to suppress bubbles caused by the dissolved
gas in the pre-treatment liquid 73c from being formed on the
surface of the substrate 2 including the inner surface 12a of the
recess 12. Thus, a plating reaction can efficiently proceed on the
surface of the substrate 2 without being affected by the bubbles,
so that the plating layer 15 can be formed on the surface of the
substrate 2 uniformly.
[0083] Furthermore, in accordance with the present example
embodiment, as described above, the ionized water containing ions
of CO.sub.2 is used as the pre-wet liquid to be supplied to the
substrate 2 in the pre-wet process (S10). For this reason, as
compared with the case where an electrically neutral processing
liquid such as DIW is supplied to the substrate 2 in advance, it is
possible to suppress electric discharge from occurring during the
plating process.
[0084] Moreover, in accordance with the present example embodiment,
as described above, the plating liquid 71c is discharged toward the
substrate 2 from the multiple discharge nozzles 34 arranged in
parallel with each other along the radial direction of the
substrate 2. For this reason, a temperature distribution of the
plating liquid 71c on the substrate 2 can be substantially uniform
regardless of the positions on the substrate 2. Thus, a thickness
of the plating layer 15 formed on the substrate 2 can also be
uniform regardless of the positions on the substrate 2.
MODIFICATION EXAMPLE
[0085] Further, in the substitution process (S21a) of the present
example embodiment, as depicted in FIG. 7, while the discharge head
53 is moved along a direction indicated by the arrow S, the
low-temperature plating liquid 74c may be discharged toward the
substrate 2 from the discharge nozzle 55a provided in the discharge
head 53. In this case, a velocity component corresponding to a
moving speed of the discharge head 53 is added to a velocity
component of the discharged plating liquid 74c. For this reason, it
is possible to increase a pressing force of the plating liquid 74c
against the pre-treatment liquid 73c along the direction S.
Further, an impact force based on kinetic energy of the plating
liquid 74c can be directly applied to the pre-treatment liquid 73c
filled in each recess 12. Thus, efficiency of substitution of the
pre-treatment liquid 73c with the plating liquid 74c can be
increased.
[0086] Further, the direction indicted by the arrow S is parallel
with, for example, a direction from the central portion of the
substrate 2 toward the peripheral portion of the substrate 2.
[0087] Furthermore, in the present example embodiment, the heating
unit 71g configured to heat the plating liquid 71c to be supplied
to the plating unit 30 is provided at the tank 71b. However, an
aspect for heating the plating liquid 71c is not limited thereto.
By way of example, the heating unit 71g may be provided at the
supply line 71a instead of at the tank 71b.
[0088] Moreover, in the present example embodiment, the tank 71b
configured to supply the high-temperature plating liquid 71c into
the film forming unit 35 and the tank 74b configured to supply the
low-temperature plating liquid 74c into the substitution unit 55
are separately provided. However, the present example embodiment is
not limited thereto. A tank configured to supply the
high-temperature plating liquid 71c into the film forming unit 35
and a tank configured to supply the low-temperature plating liquid
74c into the substitution unit 55 may be commonly provided. By way
of example, as depicted in FIG. 9, the tank 74b in which the
low-temperature plating liquid 74c is stored may be used as a
single common tank. In this case, as depicted in FIG. 9, the
heating unit 71g configured to heat a plating liquid is provided at
the supply line 71a of the film forming plating liquid supply unit
71. Thus, with the single common tank, it is possible to supply the
high-temperature plating liquid 71c into the film forming unit 35
and also possible to supply the low-temperature plating liquid 74c
into the substitution unit 55.
[0089] Further, in some cases, a plating liquid heated by the
heating unit 71g may be required not to be supplied to the
substrate 2, but to be returned back to the tank 74b. In this case,
although not illustrated, a collecting line for returning the
high-temperature plating liquid back to the tank 74b may be further
provided. Furthermore, a cooling unit for cooling a plating liquid
may be provided at the collecting line. Thus, a plating liquid
cooled to a low temperature can be returned to the tank 74b.
Moreover, the cooling unit provided at the collecting line and the
above-described heating unit 71g provided at the supply line 71a
may be configured as an integrated heat exchanger.
[0090] Furthermore, in the present example embodiment, the
discharge nozzle 34 configured to discharge the high-temperature
plating liquid 71c and the discharge nozzle 55a configured to
discharge the low-temperature plating liquid 74c are separately
provided. However, the present example embodiment is not limited
thereto. A discharge nozzle configured to discharge the
high-temperature plating liquid 71c and a discharge nozzle
configured to discharge the low-temperature plating liquid 74c may
be commonly provided.
[0091] Moreover, in the film forming process (S21b) of the present
example embodiment, the low-temperature plating liquid 74c already
filled in the recess 12 is heated by supplying the high-temperature
plating liquid 71c toward the substrate 2. However, a method of
using a high-temperature plating liquid with respect to the
substrate 2 is not limited thereto. By way of example, by heating
the substrate 2 or the turn table 112, the low-temperature plating
liquid 74c already filled in the recess 12 in the substrate 2 can
be heated, so that the high-temperature plating liquid 71c can be
obtained. Herein, a method of heating the substrate 2 is not
particularly limited, and various methods may be used. By way of
example, as depicted in FIG. 10, the film forming unit 35may
further include a substrate heating unit 36 configured to heat the
substrate 2. As the substrate heating unit, there may be used a
lamp heater 36 configured to irradiate light toward the substrate 2
to heat the substrate 2. Further, the substrate heating unit 36 may
be configured to circulate a heat transfer medium such as hot water
below the substrate 2 to heat the substrate 2. If the substrate 2
is heated from the below, a plating liquid filled in the recess 12
is heated from a lower side of the recess 12. It is advantageous to
heat a plating liquid from the lower side of the recess 12 in the
case of using a plating liquid for forming the plating layer first
on the upper portion of the recess 12. This is because a plating
reaction can be first started at the lower portion of the recess 12
by heating the plating liquid from the lower side of the recess 12.
As a result, it is possible to reduce a difference between a
thickness of the plating layer formed on the lower portion of the
recess 12 and a thickness of the plating layer formed on the upper
portion of the recess 12.
[0092] Further, in the present example embodiment, the barrier film
formed of the plating layer 15 is directly formed on the inner
surface 12a of the recess 12 formed in the insulating layer 11.
However, the present example embodiment is not limited thereto.
Another layer may be interposed between the inner surface 12a of
the recess 12 and the barrier film. By way of example, a catalyzer
layer for promoting a plating reaction may be interposed between
the inner surface 12a of the recess 12 and the barrier film. A
material of the catalyzer layer is appropriately selected depending
on the material of the plating layer. By way of example, if the
plating layer is formed of CoWB, the material of the catalyzer
layer may be Pd (palladium). An adhesion layer for improving
adhesivity between the inner surface 12a of the recess 12 and the
catalyzer layer may be further formed. The adhesion layer may be
formed by performing a SAM process using a coupling agent such as a
silane coupling agent. Further, an insulating film such as TEOS or
PI (polyimide) may be formed on the inner surface 12a of the recess
12.
[0093] Furthermore, in the present example embodiment, the plating
apparatus 20 is a single-substrate processing apparatus that
performs a plating process to a single substrate 2 by discharging a
plating liquid to the substrate 2. However, a plating apparatus to
which the technical concept of the present example embodiment can
be applied is not limited to the single-substrate processing
apparatus. By way of example, the plating apparatus in accordance
with the present example embodiment may be a so-called dip-type
processing apparatus capable of performing plating process to
multiple substrates 2 in a lump. In the dip-type processing
apparatus, by dipping the substrate 2 into a plating tank in which
a plating liquid is stored, the plating liquid is supplied to the
substrate 2. The other configuration thereof is substantially the
same as the above-described single-substrate plating apparatus 20,
and detailed explanation thereof will be omitted.
[0094] Although several modification examples of the
above-described example embodiments have been explained, it is
possible to apply an appropriate combination of the multiple
modification examples.
EXPERIMENTAL EXAMPLE
Experimental Example 1
[0095] There will be explained an example where the plating layer
15 of CoWB is formed on the inner surface 12a of the recess 12
formed in the insulating layer 11 of the substrate 2 by using the
above-described plating apparatus 20.
[0096] Firstly, the substrate 2 including the insulating layer 11
in which the recess 12 is formed is prepared. A diameter of the
recess 12 is 8 .mu.m, and a depth of the recess 12 is 100
.mu.m.
[0097] Then, the pre-wet process (S 10) is performed. Thereafter,
the pre-treatment process (S20) of discharging the pre-treatment
liquid toward the substrate 2 is performed. Thus, the inside of the
recess 12 is filled with the pre-treatment liquid. As the
pre-treatment liquid, DIW on which the deaeration process is
performed is used.
[0098] Then, the plating process (S21) of forming the plating layer
15 on the inner surface 12a of the recess 12 is performed. To be
specific, the substitution process (S21a) of discharging the
plating liquid having a temperature of 25.degree. C. toward the
substrate 2 is performed for 20 minutes. Then, the film forming
process (S21b) of discharging a plating liquid having a temperature
of 65.degree. C. toward the substrate 2 is performed for 5 minutes.
A concentration of SPS contained in each plating liquid is 5 ppm.
Thereafter, an appropriate post-treatment such as the rinsing
process (S32) is performed.
[0099] The plating layer formed by the plating process (S21) is
observed. To be specific, the plating layer formed at the upper
portion of the recess 12 and the lower portion (bottom) thereof is
observed. A result thereof is as shown in FIG. 12.
Comparative Example 1
[0100] A plating layer of CoWB is formed on the inner surface 12a
of the recess 12 in the substrate 2 in the same manner as the
experimental example 1 except that the above-described substitution
process (S21a) is not performed. That is, in the comparative
example 1, as a plating process, only the process of discharging
the plating liquid having a temperature of 65.degree. C. toward the
substrate 2 is performed for 5 minutes. The formed plating layer is
observed. A result thereof is as shown in FIG. 13.
[0101] As depicted in FIG. 13, in the comparative example 1, there
are many portions where the plating layer is not formed on the
inner surface 12a of the recess 12. Meanwhile, as depicted in FIG.
12, in the experimental example 1, the plating layer can be
uniformly formed on the inner surface 12a of the recess b 12
including both of the upper portion of the recess 12 and the lower
portion thereof. In the experimental example 1, each component of
the plating liquid can be sufficiently diffused within the recess
12 by performing the substitution process prior to the film forming
process, so that the plating layer can be uniformly formed on the
inner surface 12a of the recess 12.
EXPLANATION OF REFERENCE NUMERALS
[0102] 2: Substrate
[0103] 12: Recess
[0104] 15: Plating layer
[0105] 20: Plating apparatus
[0106] 30: Plating unit
[0107] 101: Casing
[0108] 110: Substrate holding unit
* * * * *