U.S. patent application number 14/690240 was filed with the patent office on 2015-08-13 for processes and solutions for substrate cleaning and electroless deposition.
The applicant listed for this patent is Lam Research Corporation. Invention is credited to Artur KOLICS, Nanhai LI.
Application Number | 20150225679 14/690240 |
Document ID | / |
Family ID | 41114657 |
Filed Date | 2015-08-13 |
United States Patent
Application |
20150225679 |
Kind Code |
A1 |
KOLICS; Artur ; et
al. |
August 13, 2015 |
PROCESSES AND SOLUTIONS FOR SUBSTRATE CLEANING AND ELECTROLESS
DEPOSITION
Abstract
This invention pertains to fabrication of devices. One
embodiment is a method of substrate cleaning and electroless
deposition of a cap layer for an integrated circuit. The method is
performed on a substrate having a surface comprising a metal and
dielectric damascene metallization layer. The method comprises
exposing the surface of the substrate to a cleaning solution
sufficient to clean the surface of the substrate and exposing the
surface of the substrate to an electroless deposition solution
sufficient to deposit the cap layer. Other embodiments of the
present invention include solutions to clean the substrate and
solutions to accomplish electroless deposition.
Inventors: |
KOLICS; Artur; (Dublin,
CA) ; LI; Nanhai; (Pleasanton, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lam Research Corporation |
Fremont |
CA |
US |
|
|
Family ID: |
41114657 |
Appl. No.: |
14/690240 |
Filed: |
April 17, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12407249 |
Mar 19, 2009 |
9048088 |
|
|
14690240 |
|
|
|
|
61040645 |
Mar 28, 2008 |
|
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Current U.S.
Class: |
510/175 |
Current CPC
Class: |
H01L 21/76883 20130101;
C11D 3/042 20130101; H01L 21/02041 20130101; C11D 3/2086 20130101;
C23C 16/0227 20130101; C11D 11/0047 20130101; H01L 21/02074
20130101; C11D 3/0073 20130101; H01L 21/7684 20130101; C11D 3/04
20130101 |
International
Class: |
C11D 11/00 20060101
C11D011/00; C11D 3/04 20060101 C11D003/04; C11D 3/20 20060101
C11D003/20; C11D 3/00 20060101 C11D003/00; C23C 16/02 20060101
C23C016/02; H01L 21/02 20060101 H01L021/02 |
Claims
1. A cleaning solution for cleaning a substrate for electroless
deposition of a cap layer on the substrate, the cleaning solution
comprising one or more hydroxycarboxylic acid(s) or one or more
non-alkali metal salt(s) of one or more hydroxycarboxylic
acid(s).
2. The cleaning solution of claim 1 having a pH >0.5 and <2.5
and further comprising: one or more surfactant(s); one or more
reducing agent(s); and optionally, one or more pH adjustor(s).
3. The cleaning solution of claim 1 having a pH >2.5 and <5
and further comprising: one or more surfactant(s); one or more
reducing agent(s); optionally, one or more pH adjustor(s); and
optionally, one or more complexing agent(s) for Cu(I) ions.
4. The cleaning solution of claim 1 having a pH >5 and <8 and
further comprising: one or more surfactant(s); one or more reducing
agent(s); optionally, one or more pH adjustor(s); optionally, one
or more complexing agent(s) for Cu(I) ions; optionally, one or more
corrosion inhibitor(s) substantially free of nitrogen and
substantially free of sulfur; and optionally, one or more oxygen
scavenger(s).
5. The cleaning solution of claim 1 having a pH >8 and <13
and further comprising: one or more surfactant(s); one or more
reducing agent(s); optionally, one or more pH adjustor(s);
optionally, one or more complexing agent(s) for Cu(I) ions;
optionally, one or more corrosion inhibitor(s) substantially free
of nitrogen and substantially free of sulfur; and optionally, one
or more oxygen scavenger(s).
6. The cleaning solution of claim 1 having a pH <2.5 and further
comprising: optionally, one or more surfactant(s); optionally, one
or more reducing agent(s); and optionally, one or more pH
adjustor(s).
7. The cleaning solution of claim 1 having a pH >0.5 and <2.5
and further comprising: one or more surfactant(s); one or more
reducing agent(s); optionally, one or more pH adjustor(s); and one
or more fluoride compound(s) selected from the group consisting of
hydrogen fluoride, tetrafluoroborate, and non-metal salts of
hydrofluoric acid.
8. The cleaning solution of claim 1 having a pH >2.5 and <5
and further comprising: one or more surfactant(s); one or more
reducing agent(s); optionally, one or more pH adjustor(s);
optionally, one or more complexing agent(s) for Cu(I) ions; and one
or more fluoride compound(s) selected from the group consisting of
hydrogen fluoride, tetrafluoroborate, and non-metal salts of
hydrofluoric acid.
9. The cleaning solution of claim 1 having a pH >5 and <8 and
further comprising: one or more surfactant(s); one or more reducing
agent(s); optionally, one or more pH adjustor(s); optionally, one
or more complexing agent(s) for Cu(I) ions; optionally, one or more
corrosion inhibitor(s) substantially free of nitrogen and
substantially free of sulfur; optionally, one or more oxygen
scavenger(s); and one or more fluoride compound(s) selected from
the group consisting of hydrogen fluoride, tetrafluoroborate, and
non-metal salts of hydrofluoric acid.
10. The cleaning solution of claim 1 having a pH >8 and <13
and further comprising: one or more surfactant(s); one or more
reducing agent(s); optionally, one or more pH adjustor(s);
optionally, one or more complexing agent(s) for Cu(I) ions;
optionally, one or more corrosion inhibitor(s) substantially free
of nitrogen and substantially free of sulfur; optionally, one or
more oxygen scavenger(s); and one or more fluoride compound(s)
selected from the group consisting of hydrogen fluoride,
tetrafluoroborate, and non-metal salts of hydrofluoric acid.
11. The cleaning solution of claim 1 having a pH <2.5 and
further comprising: optionally, one or more surfactant(s);
optionally, one or more reducing agent(s); optionally, one or more
pH adjustor(s); and one or more fluoride compound(s) selected from
the group consisting of hydrogen fluoride, tetrafluoroborate, and
non-metal salts of hydrofluoric acid; the pH of the cleaning
solution is.
12. The cleaning solution of claim 1 having a pH <2.5 and
further comprising: one or more oxidizer(s); optionally, one or
more surfactant(s); and optionally, one or more pH adjustor(s).
13. The cleaning solution of claim 1 having a pH >1 and <6
and further comprising: one or more surfactant(s); optionally, one
or more reducing agent(s); and optionally, one or more pH
adjustor(s); wherein the electroless deposition of the cap layer is
accomplished using an electroless deposition solution comprising:
the one or more hydroxycarboxylic acid(s) or the one or more
non-alkali metal salt(s) of the one or more hydroxycarboxylic
acid(s); the one or more surfactant(s); optionally, the one or more
reducing agent(s); and optionally, the one or more pH
adjustor(s).
14. The cleaning solution of claim 1 having a pH >1 and <6
and further comprising: optionally, one or more surfactant(s);
optionally, one or more reducing agent(s); and optionally, one or
more pH adjustor(s); wherein the electroless deposition of the cap
layer is accomplished using an electroless deposition solution
comprising: the one or more hydroxycarboxylic acid(s) or the one or
more non-alkali metal salt(s) of the one or more hydroxycarboxylic
acid(s); one or more surfactant(s); optionally, the one or more
reducing agent(s); and optionally, the one or more pH adjustor(s).
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S. patent
application Ser. No. 12/407,249 filed on Mar. 19, 2009 and entitled
"Processes and Solutions for Substrate Cleaning and Electroless
Deposition" by Kolics et al., which claims benefit of U.S. Patent
Application No. 61/040,645 entitled "Processes and Solutions for
Substrate Cleaning and Electroless Deposition" by Kolics et al,
filed Mar. 28, 2008, all of which are incorporated herein, in its
entirety, by this reference.
BACKGROUND
[0002] This invention pertains to fabrication of electronic devices
such as integrated circuits; more specifically, this invention
relates to methods and formulations for cleaning substrates prior
to electroless deposition of cap layers on metal and dielectric
damascene metallization structures.
[0003] The cleaning process for patterned substrates prior to
electroless deposition of cap layers on metal interconnects such as
copper interconnects is crucial for electroless plating processes.
A clean substrate surface is needed to ensure good deposition
selectivity, low defect counts, and low etching of the metal
interconnect. Using copper technology as an example, the surface of
the patterned substrates includes copper interconnect structures
embedded in a dielectric, i.e., damascene or dual damascene
structures, formed in part by chemical mechanical planarization
(CMP). The cap layer is deposited on the copper after CMP. Examples
of materials for the cap layer are materials such as cobalt, cobalt
alloy, cobalt tungsten, cobalt-nickel alloy, nickel, and nickel
alloy. There are many post-CMP cleaning solutions used for cleaning
patterned substrates prior to electroless deposition of the cap
layer. However, the goals of post-CMP cleaning and the goals of
cleaning for electroless deposition of the cap layer are not the
same. Consequently, post-CMP cleaning solutions may not produce the
type of clean surface needed for electroless deposition of
high-quality cap layers. For instance, many of the standard
technology cleaning solutions remove only the outer oxide (cupric
oxide) film from the copper surface while leaving the inner, mostly
cuprous oxide, intact on the surface to passivate the copper.
Another common approach attempts to minimize copper etching by
including copper corrosion inhibitors in the post-CMP clean
solution. Some of the corrosion inhibitors or the copper oxide, if
left on the surface before electroless plating, can create
significant problems for the electroless deposition process such as
causing no or spotty plating on the copper, formation of
pinholes/pits in the cap layer, poor adhesion between the substrate
and the cap layer, or extra cap layer deposition on the
dielectric.
[0004] There is a need for improved processes and solutions for
depositing cap layers on substrates used to fabricate devices such
as electronic devices. More specifically, there is a need for
improved cleaning solutions and methods of cleaning substrates that
can produce contamination and defect free substrate surfaces for
electroless deposition of cap layers that can be used to meet the
performance and manufacturing requirements for such devices.
SUMMARY
[0005] This invention pertains to fabrication of electronic
devices. One embodiment of the present invention is a method of
substrate cleaning and electroless deposition of a cap layer for an
integrated circuit. The method is performed on a substrate having a
surface comprising a metal and dielectric damascene metallization
layer. The method comprises exposing the surface of the substrate
to a cleaning solution sufficient to clean the surface of the
substrate; and substantially without dewetting or drying the
surface of the substrate, exposing the surface of the substrate to
an electroless deposition solution sufficient to deposit the cap
layer. Other embodiments of the present invention include solutions
to clean the substrate and solutions to accomplish electroless
deposition.
[0006] It is to be understood that the invention is not limited in
its application to the details of construction and to the
arrangements of the components set forth in the following
description or illustrated in the drawings. The invention is
capable of other embodiments and of being practiced and carried out
in various ways. In addition, it is to be understood that the
phraseology and terminology employed herein are for the purpose of
description and should not be regarded as limiting.
[0007] As such, those skilled in the art will appreciate that the
conception, upon which this disclosure is based, may readily be
utilized as a basis for the designing of other structures, methods,
and systems for carrying out aspects of the present invention. It
is important, therefore, that the claims be regarded as including
such equivalent constructions insofar as they do not depart from
the spirit and scope of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a process flow diagram of an embodiment of the
present invention.
[0009] FIG. 2 is a process flow diagram of an embodiment of the
present invention.
[0010] FIG. 3 is a process flow diagram of an embodiment of the
present invention.
[0011] FIG. 4 is a process flow diagram of an embodiment of the
present invention.
[0012] FIG. 5 is a process flow diagram of an embodiment of the
present invention.
[0013] FIG. 6 is a process flow diagram of an embodiment of the
present invention.
[0014] FIG. 7 is a process flow diagram of an embodiment of the
present invention.
[0015] FIG. 8 is a process flow diagram of an embodiment of the
present invention.
[0016] FIG. 9 is a process flow diagram of an embodiment of the
present invention.
[0017] FIG. 10 is a process flow diagram of an embodiment of the
present invention.
[0018] FIG. 11 is a process flow diagram of an embodiment of the
present invention.
[0019] FIG. 12 is a process flow diagram of an embodiment of the
present invention.
[0020] FIG. 13 is a process flow diagram of an embodiment of the
present invention.
[0021] FIG. 14 is a process flow diagram of an embodiment of the
present invention.
[0022] FIG. 15 is a process flow diagram of an embodiment of the
present invention.
[0023] FIG. 16 is a process flow diagram of an embodiment of the
present invention.
[0024] FIG. 17 is a process flow diagram of an embodiment of the
present invention.
[0025] FIG. 18 is a process flow diagram of an embodiment of the
present invention.
[0026] FIG. 19 is a process flow diagram of an embodiment of the
present invention.
[0027] FIG. 20 is a process flow diagram of an embodiment of the
present invention.
DESCRIPTION
[0028] The present invention pertains to interconnect metallization
that uses an electrically conductive metal with a cap and a
dielectric forming a damascene metallization structure for devices
such as integrated circuits. More particularly, the present
invention pertains to interconnect metallization layers that
include a dielectric and a metal, such as copper. The fabrication
of the devices requires methods and solutions to clean substrates
and methods and solutions to accomplish electroless deposition of
the cap layer on the substrates.
[0029] To overcome one or more problems of the standard technology,
some embodiments of the present invention include either a two-step
cleaning process or a one-step acidic cleaning process. In order to
minimize the copper etching, some embodiments of the present
invention include or use electroless-deposition compatible
corrosion inhibitors and/or an inert environment during the
cleaning process.
[0030] For some applications of embodiments of the present
invention, the cleaning and the electroless deposition are done in
the same process chamber. The cleaning process or at least the
second clean of a two-step cleaning process is preferably done with
a cleaning solution that includes one or more additive(s) present
in the electroless deposition solution. This is preferred if the
second cleaning solution is not rinsed off from the substrate
surface before the electroless deposition.
[0031] Embodiments of the present invention will be discussed
below, primarily in the context of processing semiconductor wafers
such as silicon wafers used for fabricating integrated circuits.
The metallization layers for the integrated circuits include copper
for metal lines formed into damascene or dual damascene dielectric
structures. Optionally, the dielectric is a dielectric such as
silicon dioxide or a low k dielectric material such as a carbon
doped silicon oxide (SiOC:H). However, it is to be understood that
embodiments in accordance with the present invention may be used
for other semiconductor devices, metals other than copper, and
wafers other than semiconductor wafers.
[0032] One aspect of the present invention includes solutions for
processing substrates such as semiconductor wafers. According to
one embodiment of the present invention, the solutions are cleaning
solutions for cleaning the surface of the substrates in preparation
for deposition of a cap layer on the substrate. Solutions according
to embodiments of the present invention have compositions so as to
be sufficient to clean the surface of the substrate. The deposition
of the cap layer is accomplished with an electroless deposition
solution sufficient to deposit the cap layer on the substrate.
Preferably, at least the final portion of cleaning the surface of
the substrate is accomplished using a cleaning solution composition
wherein the cleaning solution only comprises components that
substantially do not obstruct the operation or performance of the
electroless deposition solution if present therein. More
specifically, the cleaning solution for at least the final portion
of cleaning the surface of the substrate is sufficient to clean the
substrate without including components that could poison, degrade,
decrease selectivity, or otherwise hinder the operation of the
electroless deposition solution for the deposition of the cap
layer. Preferably, the cleaning solution composition is selected so
that one or more components of the cleaning solution are also
components intentionally included in the electroless deposition
solution for the cap layer.
[0033] In the following description of the figures, identical
reference numerals have been used when designating substantially
identical elements or steps that are common to the figures. Also
for the present description and claims, the word "or" is used as a
non-exclusive relation having substantially the same meaning as
"and/or," unless specified otherwise.
Solution Compositions
[0034] One embodiment of the present invention includes a cleaning
solution, (a), comprising an aqueous solution of one or more
hydroxycarboxylic acid(s) or one or more non-alkali metal salt(s)
of one or more hydroxycarboxylic acid(s). This means that the
cleaning solution may have any of or more compositions such as a
hydroxycarboxylic acid; more than one hydroxycarboxylic acid; a
non-alkali metal salt of a hydroxycarboxylic acid; more than one
non-alkali metal salt of a hydroxycarboxylic acid; a
hydroxycarboxylic acid mixed with a non-alkali metal salt of a
hydroxycarboxylic acid; one or more hydroxycarboxylic acid(s) mixed
with one or more non-alkali metal salt(s) of one or more
hydroxycarboxylic acid(s). For preferred embodiments, the
components of the cleaning solution are selected so that the
cleaning of the substrate and the electroless deposition on the
substrate are done without drying or dewetting the substrate.
[0035] An embodiment of the present invention includes a cleaning
solution, (b), comprising an aqueous solution of one or more
hydroxycarboxylic acid(s) or one or more non-alkali metal salt(s)
of one or more hydroxycarboxylic acid(s); one or more
surfactant(s); one or more reducing agent(s); and optionally, one
or more pH adjustor(s). The pH of the cleaning solution is >0.5
and <2.5.
[0036] Another embodiment of the present invention includes a
cleaning solution, (c), comprising an aqueous solution of one or
more hydroxycarboxylic acid(s) or one or more non-alkali metal
salt(s) of one or more hydroxycarboxylic acid(s); one or more
surfactant(s); one or more reducing agent(s); optionally, one or
more pH adjustor(s); and optionally, one or more complexing
agent(s) for Cu(I) ions. The pH of the cleaning solution is >2.5
and <5.
[0037] Another embodiment of the present invention includes a
cleaning solution, (d), comprising an aqueous solution of one or
more hydroxycarboxylic acid(s) or one or more non-alkali metal
salt(s) of one or more hydroxycarboxylic acid(s); one or more
surfactant(s); one or more reducing agent(s); optionally, one or
more pH adjustor(s); optionally, one or more complexing agent(s)
for Cu(I) ions; optionally, one or more corrosion inhibitor(s)
substantially free of nitrogen and substantially free of sulfur;
and optionally, one or more oxygen scavenger(s). The pH of the
cleaning solution is >5 and <8.
[0038] Another embodiment of the present invention includes a
cleaning solution, (e), comprising an aqueous solution of one or
more hydroxycarboxylic acid(s) or one or more non-alkali metal
salt(s) of one or more hydroxycarboxylic acid(s); one or more
surfactant(s); one or more reducing agent(s); optionally, one or
more pH adjustor(s); optionally, one or more complexing agent(s)
for Cu(I) ions; optionally, one or more corrosion inhibitor(s)
substantially free of nitrogen and substantially free of sulfur;
and optionally, one or more oxygen scavenger(s). The pH of the
cleaning solution is >8 and <13.
[0039] Another embodiment of the present invention includes a
cleaning solution, (f), comprising an aqueous solution of one or
more hydroxycarboxylic acid(s) or one or more non-alkali metal
salt(s) of one or more hydroxycarboxylic acid(s); optionally, one
or more surfactant(s); optionally, one or more reducing agent(s);
and optionally, one or more pH adjustor(s). The pH of the cleaning
solution is <2.5.
[0040] Another embodiment of the present invention includes a
cleaning solution, (g), comprising an aqueous solution of one or
more hydroxycarboxylic acid(s) or one or more non-alkali metal
salt(s) of one or more hydroxycarboxylic acid(s); one or more
surfactant(s); one or more reducing agent(s); optionally, one or
more pH adjustor(s); and one or more fluoride compound(s) selected
from the group consisting of hydrogen fluoride, tetrafluoroborate,
and non-metal salts of hydrofluoric acid. The pH of the cleaning
solution is >0.5 and <2.5.
[0041] Another embodiment of the present invention includes a
cleaning solution, (h), comprising an aqueous solution of one or
more hydroxycarboxylic acid(s) or one or more non-alkali metal
salt(s) of one or more hydroxycarboxylic acid(s); one or more
surfactant(s); one or more reducing agent(s); optionally, one or
more pH adjustor(s); optionally, one or more complexing agent(s)
for Cu(I) ions; and one or more fluoride compound(s) selected from
the group consisting of hydrogen fluoride, tetrafluoroborate, and
non-metal salts of hydrofluoric acid. The pH of the cleaning
solution is >2.5 and <5.
[0042] Another embodiment of the present invention includes a
cleaning solution, (i), comprising an aqueous solution of one or
more hydroxycarboxylic acid(s) or one or more non-alkali metal
salt(s) of one or more hydroxycarboxylic acid(s); one or more
surfactant(s); one or more reducing agent(s); optionally, one or
more pH adjustor(s); optionally, one or more complexing agent(s)
for Cu(I) ions; optionally, one or more corrosion inhibitor(s)
substantially free of nitrogen and substantially free of sulfur;
optionally, one or more oxygen scavenger(s); and one or more
fluoride compound(s) selected from the group consisting of hydrogen
fluoride, tetrafluoroborate, and non-metal salts of hydrofluoric
acid. The pH of the cleaning solution is >5 and <8.
[0043] Another embodiment of the present invention includes a
cleaning solution, (j), comprising an aqueous solution of one or
more hydroxycarboxylic acid(s) or one or more non-alkali metal
salt(s) of one or more hydroxycarboxylic acid(s); one or more
surfactant(s); one or more reducing agent(s); optionally, one or
more pH adjustor(s); optionally, one or more complexing agent(s)
for Cu(I) ions; optionally, one or more corrosion inhibitor(s)
substantially free of nitrogen and substantially free of sulfur;
optionally, one or more oxygen scavenger(s); and one or more
fluoride compound(s) selected from the group consisting of hydrogen
fluoride, tetrafluoroborate, and non-metal salts of hydrofluoric
acid. The pH of the cleaning solution is >8 and <13.
[0044] Another embodiment of the present invention includes a
cleaning solution, (k), comprising an aqueous solution of one or
more hydroxycarboxylic acid(s) or one or more non-alkali metal
salt(s) of one or more hydroxycarboxylic acid(s); optionally, one
or more surfactant(s); optionally, one or more reducing agent(s);
optionally, one or more pH adjustor(s); and one or more fluoride
compound(s) selected from the group consisting of hydrogen
fluoride, tetrafluoroborate, and non-metal salts of hydrofluoric
acid. The pH of the cleaning solution is <2.5.
[0045] Another embodiment of the present invention includes a
cleaning solution, (l), comprising an aqueous solution of one or
more hydroxycarboxylic acid(s) or one or more non-alkali metal
salt(s) of one or more hydroxycarboxylic acid(s); optionally, one
or more surfactant(s); one or more oxidizer(s); and optionally, one
or more pH adjustor(s). The pH of the cleaning solution is
<2.5.
[0046] Another embodiment of the present invention includes a
cleaning solution, (m), comprising an aqueous solution of one or
more hydroxycarboxylic acid(s) or one or more non-alkali metal
salt(s) of one or more hydroxycarboxylic acid(s); one or more
surfactant(s); optionally, one or more reducing agent(s); and
optionally, one or more pH adjustor(s). The pH of the cleaning
solution is >1 and <6. The cleaning solution for this
embodiment of the present invention is preferably used prior to
electroless deposition of a cap layer that is accomplished with an
electroless deposition solution comprising the one or more
hydroxycarboxylic acid(s) or the one or more non-alkali metal
salt(s) of the one or more hydroxycarboxylic acid(s); the one or
more surfactant(s); optionally, the one or more reducing agent(s);
and optionally, the one or more pH adjustor(s) used in the cleaning
solution.
[0047] Another embodiment of the present invention includes a
cleaning solution, (n), comprising an aqueous solution of one or
more hydroxycarboxylic acid(s) or one or more non-alkali metal
salt(s) of one or more hydroxycarboxylic acid(s); optionally, one
or more surfactant(s); optionally, one or more reducing agent(s);
and optionally, one or more pH adjustor(s). The pH of the cleaning
solution is >1 and <6. The cleaning solution for this
embodiment of the present invention is preferably used prior to
electroless deposition of a cap layer that is accomplished with an
electroless deposition solution comprising the one or more
hydroxycarboxylic acid(s) or the one or more non-alkali metal
salt(s) of the one or more hydroxycarboxylic acid(s); the one or
more surfactant(s); optionally, the one or more reducing agent(s);
and optionally, the one or more pH adjustor(s) used in the cleaning
solution.
[0048] The cleaning solutions presented above are summarized in
TABLE 1. Shown in TABLE 1 are the pH range for the cleaning
solution, additives present in the cleaning solution indicated with
"P" for present, and additives that are optionally present
indicated with "O" for optional. Each of the additives is given a
Roman numeral notation that is defined at the bottom of the
table.
[0049] For embodiments of the present invention, suitable
hydroxycarboxylic acids include substantially any organic compound
which has at least one carboxylic group (--COOH) and at least one
hydroxy group (--OH). The hydroxy group (--OH) is attached to an
alkyl group; consequently, compounds such as phenols and their
derivatives are excluded. Numerous compounds are suitable for use
as the hydroxycarboxylic acids or non-alkali metal salts of
hydroxycarboxylic acids in embodiments of the present invention.
Hydroxycarboxylic acids for embodiments of the present invention
preferably have the general formula HO--R--COOH where R is an alky
hydrocarbon. Embodiments of the present invention include one or
more carboxylic groups (--COOH) and one or more hydroxy groups
(--OH) attached to the alky hydrocarbon. Examples of
hydroxycarboxylic acids for embodiments of the present invention
include, but are not limited to, citric acid
(2-hydroxy-1,2,3-propane tricarboxylic acid), lactic acid
(2-hydroxypropanoic acid), and malonic acid (propanedioic acid).
Preferred embodiments of the present invention use concentrations
of the hydroxycarboxylic acid or non-alkali metal salt of the
hydroxycarboxylic acid in the range from about 0.005 g/L to about
100 g/L.
[0050] Embodiments of the present invention may include cleaning
solutions that contain one or more additional additives. As an
option, some embodiments of the present invention may include
cleaning solutions that also contain one or more surfactant(s). The
surfactant is included so as to provide adequate wetting of the
substrate during the cleaning. Preferably, the entire surface of
the substrate is adequately wetted by the cleaning solution so that
the dielectric areas of the substrate are wetted and the metal
areas of the substrate are wetted. Numerous compounds are suitable
for use as surfactants in embodiments of the present invention. A
list of surfactants for embodiments of the present invention
includes, but is not limited to, anionic surfactants, cationic
surfactants, nonionic surfactants, amphoteric surfactants, and
combinations thereof. Some embodiments of the present invention
include one or more surfactant(s) in the cleaning solution in
amounts ranging from about 10 parts per million to about 2000 parts
per million.
[0051] As an option, some embodiments of the present invention
include cleaning solutions that also contain one or more reducing
agent(s). The reducing agent is selected so as to be substantially
incapable of scavenging for dissolved oxygen. More specifically,
the reducing agent is selected so as to provide a function other
than scavenging for dissolved oxygen in the cleaning solution. A
primary function of the reducing agent is to minimize unwanted
anodic dissolution of the metal. Depending on the type of reducing
agent, the oxidation of these compounds is energetically more
favorable than the oxidation and dissolution of the copper.
Numerous compounds are suitable for use as reducing agents in
embodiments of the present invention. A list of reducing agents for
some embodiments of the present invention includes, but is not
limited to, boron containing reducing agents, hypophosphites,
aldehydes, and combinations thereof. Some embodiments of the
present invention include one or more reducing agents in the
cleaning solution in amounts ranging from about 0.005 gram per
liter to about 35 grams per liter.
[0052] As an option for some embodiments of the present invention,
the cleaning solution further comprises one or more pH adjustor(s)
to produce the pH or pH range for the cleaning solution. As an
option, the pH adjustors can be organic or non-halide containing
inorganic acids with a pK.sub.a value less than 2.5. The pH
adjustor can also be organic or non-halide containing inorganic
bases such as amines or imines with a pK.sub.b value above 7.5.
Preferably, cleaning solutions according to embodiments of the
present invention substantially do not include inorganic acids
having strong oxidizing character such as nitric acid and such as
peroxodisulfuric acid. It is also preferred that cleaning solutions
according to embodiments of the present invention substantially do
not include metal containing acids such as chromic acid. It is to
be understood that the amount of the one or more pH adjustor(s) is
selected so as to be sufficient to provide a desired pH for the
cleaning solution. The amount will be determined, in part, by the
desired pH for the cleaning solution, the chemical properties of
the pH adjustor, and the amount and chemical properties of the
other components of the cleaning solution. In summary, an effective
amount of the one or more pH adjustor(s) is included so as to
produce the desired pH for the cleaning solution.
[0053] As an option, some embodiments of the present invention may
include cleaning solutions that also contain one or more complexing
agent(s) for Cu(I) ions. Numerous compounds are suitable for use as
complexing agents in embodiments of the present invention. A list
of complexing agents for embodiments of the present invention
includes, but is not limited to, all non-sulfur containing
complexing agents which form at least the same or more stable
complexes with Cu(I) ions than with Cu(II) ions. A list of
complexing agents for some embodiments of the present invention
includes, but is not limited to, carboxylic acids,
hydroxycarboxylic acids, amino acids, phosphonic acid, phytic acid,
and combinations thereof. Some embodiments of the present invention
include one or more complexing agent(s) in the cleaning solution in
amounts ranging from about 0.1 gram per liter to about 50 grams per
liter.
[0054] As an option, some embodiments of the present invention may
include cleaning solutions that also contain one or more corrosion
inhibitor(s) free of nitrogen and sulfur to substantially protect
the metal or retard the dissolution of the metal in the cleaning
solution. Numerous compounds are suitable for use as corrosion
inhibitors in embodiments of the present invention. Some
embodiments of the present invention include one or more corrosion
inhibitors in the cleaning solution in amounts ranging from about
0.01 gram per liter to about 5 grams per liter.
[0055] As an option, some embodiments of the present invention may
include cleaning solutions that also contain one or more oxygen
scavenger(s) to remove dissolved oxygen from the cleaning solution.
More specifically, the oxygen scavenger provides a lower
concentration of dissolved oxygen in the cleaning solution.
Preferably, the amount of dissolved oxygen is kept to a minimum so
as to substantially prevent oxidation of the metal by the dissolved
oxygen. Numerous compounds are suitable for use as oxygen
scavengers for dissolved oxygen in embodiments of the present
invention. Some embodiments of the present invention include one or
more oxygen scavengers present in the cleaning solution in amounts
ranging from about 0.1 gram per liter to about 50 grams per liter.
Preferred embodiments of the present invention maintain
concentrations of dissolved oxygen in the cleaning solution at less
than 5 parts per million (ppm). For some embodiments of the present
invention, the low levels of dissolved oxygen are obtained by
providing a sufficient amount of one or more oxygen
scavengers(s).
[0056] As an option, some embodiments of the present invention may
include cleaning solutions that also contain one or more fluoride
compounds(s). The fluoride compounds are provided so as to improve
the cleaning solution. Preferred embodiments of the present
invention use fluoride compounds such as hydrogen fluoride,
tetrafluoroborate, non-metal salts of hydrofluoric acid, and
mixtures thereof. Some embodiments of the present invention include
one or more of the fluoride compound(s) in the cleaning solution in
amounts ranging from about 0.1% to about 0.5%.
[0057] As an option, some embodiments of the present invention may
include cleaning solutions that also contain one or more
oxidizer(s). The oxidizers are provided so as to improve the
cleaning capability of the cleaning solution. Some embodiments of
the present invention include one or more of the oxidizer(s) in the
cleaning solution in amounts ranging from about 0.1 gram per liter
to about 50 grams per liter.
[0058] As an option for some embodiments of the present invention,
some of the cleaning solutions are particularly suitable for
processes that include using a single cleaning solution.
Alternatively, other processes may include using a first cleaning
solution for an initial cleaning of the substrate and a second
cleaning solution for a more thorough or final cleaning of the
substrate. TABLE 2 shows a subset of cleaning solutions listed in
TABLE 1 that are particularly suited for use as a single cleaning
solution. Similarly, TABLE 3 shows a subset of cleaning solutions
listed in TABLE 1 that are particularly suited for use as a first
cleaning solution. TABLE 4 shows a subset of cleaning solutions
listed in TABLE 1 that are particularly suited for use as a second
cleaning solution.
[0059] Cleaning solutions according to embodiments of the present
invention can be integrated into manufacturing operations to
produce electronic devices by way of a variety of process flows.
Furthermore, some of the cleaning solutions according to
embodiments of the present invention have compositions which allow
the implementation of process flows that cannot be or cannot be
easily accomplished using standard cleaning solutions for such
applications. In other words, cleaning solutions according to
embodiments of the present invention enable the use of process
flows that can yield improved results for the substrates and/or
improvements in manufacturing productivity.
Process Flows
[0060] Reference is now made to FIG. 1 where there is shown a
process flow 30 for use in the fabrication of devices according to
one embodiment of the present invention. The process flow 30 begins
with start 50 and further includes a clean with solution 75, an
electroless plating 150, and is completed with end 175. The process
flow 30 is performed on a substrate having a metal and dielectric
damascene metallization; preferably the metal is copper and the
dielectric is a low k dielectric. The clean with solution 75
involves cleaning the surface of the substrate in preparation for
electroless deposition of a cap layer on the copper. Although the
cap layer is substantially only deposited onto the copper portions
of the substrate, substantially the entire surface of the substrate
needs to be cleaned, including both the copper areas and the
dielectric areas.
[0061] For the process flow 30, the clean with solution 75 is
accomplished using one of the cleaning solutions substantially as
disclosed above. More specifically, the cleaning solution is
exposed to the surface of the substrate so that the substrate is
wetted by the cleaning solution. As an option, the cleaning
solution may be a cleaning solution particularly suited for use in
a single cleaning process. Cleaning solutions for such processes
are preferably selected from cleaning solutions such as those
listed in TABLE 2 described above. Preferably, the cleaning
solution only comprises components that substantially do not
obstruct the operation or performance of the electroless deposition
solution if present therein. In other words, the components of the
cleaning solution may be present in the electroless deposition
solution as an intentional addition to the electroless deposition
solution or as a result such as from being dragged into the
electroless deposition solution or present from a cleaning solution
residue from the substrate.
[0062] Alternatively, the clean with solution 75 can be
accomplished using two cleaning solutions substantially as
disclosed above. More specifically, a first cleaning solution can
be exposed to the substrate to accomplish an initial clean of the
substrate; later, a second cleaning solution can be exposed to the
substrate to accomplish a more thorough or final clean of the
substrate. The first cleaning solution is preferably a cleaning
solution such as those presented in TABLE 3. The second cleaning
solution is preferably a cleaning solution such as those presented
in TABLE 4.
[0063] In general, the clean with solution 75 includes wetting the
surface of the substrate to be cleaned with the cleaning solution.
The cleaning solution has properties sufficient to accomplish the
clean or a portion thereof. The cleaning solution is applied to the
surface to be cleaned under conditions sufficient for the clean.
More specifically, factors such as solution compositions, contact
time with the surface to be cleaned, and temperature are selected
to be sufficient for the clean.
[0064] The electroless plating 150 is also accomplished using wet
processing. Descriptions of some technologies for electroless
deposition of cap layers for device metallization applications can
be found in U.S. patents: U.S. Pat. No. 6,794,288 to Kolics, U.S.
Pat. No. 6,902,605 to Kolics, and U.S. Pat. No. 6,911,067 to
Kolics; the contents of all of these patents and/or applications
are incorporated herein, in their entirety, by this reference.
[0065] One of the benefits of using solutions according to
embodiments of the present invention is that, as an option, the
process flow 30 can be performed substantially without dewetting or
drying the surface of the substrate. In other words, the surface of
the substrate to be cleaned and later subjected to electroless
deposition has a layer of liquid present, i.e. is wetted,
throughout the process flow 30 from the start 50 through to the end
175. According to preferred embodiments of the present invention,
the process flow 30 is performed with a substrate maintained wetted
from the start 50 through to the end 175. The wetted substrate has
a substantially continuous film of liquid over the surface such as
having the surface of the substrate hydrophilic with respect to the
liquid. The wetted substrate is in contrast to either a de-wetted
substrate or a dry substrate. The de-wetted substrate is one where
the film of the liquid has been broken so that droplets may be
formed on the substrate and areas of the substrate are uncovered by
the liquid. The dry substrate is one where the film of liquid is
substantially absent and substantially the entire substrate surface
is uncovered by the liquid. Preferred embodiments of the process
flow 30 are performed so that the clean with solution 75 and the
electroless plating 150 and all other acts that may be included
between the start 50 and the end 175 do not include drying or
dewetting the substrate.
[0066] The exclusion of drying steps and the exclusion of dewetting
steps for the process flow 30 increases the productivity for
processing the substrates. This is in contrast to the standard
processing of substrates where typically there are one or more
drying steps during and/or between cleaning the substrate and
electroless deposition of the cap layer. Another benefit that is
believed to occur for embodiments of the present invention is that
the exclusion of drying steps and the exclusion of dewetting steps
for the process flow 30 also produces improvements in cleaning the
substrate and/or maintaining the cleaned substrate.
[0067] As indicated above, an option for embodiments of the present
invention includes using two cleaning solutions to clean a
substrate. Such an embodiment will now be described with reference
to FIG. 2 where there is shown a process flow 32. The process flow
32 is substantially the same as process flow 30 with the exception
that clean with solution 75 has been replaced with clean with first
solution 110 and clean with second solution 130. More specifically,
the process flow 32 begins with start 50 and further includes clean
with first solution 110, clean with second solution 130,
electroless plating 150, and is completed with end 175. For process
flow 32, the electroless plating 150 is essentially the same as
described above for process flow 30. The clean with first solution
110 includes using a cleaning solution such as one of the cleaning
solutions listed in TABLE 3. The clean with second solution 130
includes using a cleaning solution such as one of the cleaning
solutions listed in TABLE 4. The clean with first solution 110 is
accomplished by exposing the substrate to a first cleaning solution
so that the first cleaning solution wets substantially the entire
surface of the substrate to be cleaned. The clean with second
solution 130 is accomplished by exposing the substrate to a second
cleaning solution so that the second cleaning solution wets
substantially the entire surface to be cleaned for the
substrate.
[0068] As an option for some embodiments of the present invention,
process flow 30 and/or process flow 32 may include additional acts
such as acts to rinse the substrate and such as acts to spin the
substrate to remove excess liquid substantially without drying or
dewetting the surface of the substrate. The acts to rinse the
substrate include wetting the surface of the substrate with
deionized water or deionized water having one or more
surfactant(s). The deionized water or deionized water having one or
more surfactants is exposed to the substrate so as to wet
substantially the entire surface of the substrate. The acts to spin
the substrate include spinning the substrate at a velocity
sufficient to reduce the amount of liquid, i.e., spinning off
excess liquid, on the surface of the substrate substantially
without dewetting or drying the substrate. In other words, the acts
to spin the substrate to remove excess liquid is performed so that
the substrate maintains a substantially continuous film of liquid
while reducing the total amount of liquid on the substrate surface.
Optionally, the one or more act(s) to rinse the substrate and/or
the one or more act(s) to spin the substrate may be executed
before, during, or after the exposing the surface of the substrate
to the cleaning solution; preferably, all are performed
substantially without drying or dewetting the substrate. The acts
to spin the substrate may be used to remove excess liquid provided
to rinse the substrate or to remove excess cleaning solution such
as the single cleaning solutions, the first cleaning solutions, and
the second cleaning solutions described above.
[0069] Reference is now made to FIG. 3 where there is shown a
process flow 34 according to an embodiment of the present
invention. The process flow 34 is substantially the same as process
flow 32 but having additional modifications. The process flow 34
begins with start 50 and includes clean with first solution 110,
spin 115, rinse 120, spin 125, clean with second solution 130, spin
135, rinse 140, spin 145, electroless plating 150, and is completed
with end 175. For process flow 34, the clean with first solution
110, the clean with second solution 130, and the electroless
plating 150 are essentially the same as described above for process
flow 32.
[0070] The spin 115 includes spinning the substrate at a velocity
sufficient to reduce the amount of a first cleaning solution used
for the clean with first solution 110, i.e., spinning off excess
liquid. For preferred embodiments, excess liquid on the surface of
the substrate is removed substantially without dewetting or drying
the substrate.
[0071] The rinse 120 includes wetting the surface of the substrate
with deionized water or deionized water having one or more
surfactant(s). The deionized water or deionized water having one or
more surfactants is exposed to the substrate so as to wet
substantially the entire surface of the substrate subjected to the
first cleaning solution.
[0072] The spin 125 includes spinning the substrate at a velocity
sufficient to reduce the amount of the deionized water or the
deionized water having one or more surfactant(s) used for the rinse
120, i.e., spinning off excess liquid. For preferred embodiments,
excess liquid on the surface of the substrate is removed
substantially without dewetting or drying the substrate.
[0073] The spin 135 includes spinning the substrate at a velocity
sufficient to reduce the amount of a second cleaning solution used
for the clean with second solution 110, i.e., spinning off excess
liquid. More specifically, excess liquid on the surface of the
substrate is removed substantially without dewetting or drying the
substrate.
[0074] The rinse 140 includes wetting the surface of the substrate
with deionized water or deionized water having one or more
surfactant(s). The deionized water or deionized water having one or
more surfactant(s) is exposed to the substrate so as to wet
substantially the entire surface of the substrate subjected to the
second cleaning solution.
[0075] The spin 145 includes spinning the substrate at a velocity
sufficient to reduce the amount of the deionized water or the
deionized water having one or more surfactant(s) used for the rinse
140, i.e., spinning off excess liquid. For preferred embodiments,
excess liquid on the surface of the substrate is removed
substantially without dewetting or drying the substrate.
[0076] Preferred embodiments of process flow 34 include using a
first cleaning solution such as first cleaning solutions shown in
TABLE 3 and a second cleaning solution such as second cleaning
solutions shown in TABLE 4. In more preferred embodiments, process
flow 34 uses a first cleaning solution such as cleaning solutions
identified above as (b), (c), (d), (e), (f), (g), (h), (i), (j),
(k), and (l) and uses a second cleaning solution such as cleaning
solutions identified above as (b), (c), (d), (g), (h), (i), (j),
(k), (l), (m), and (n).
[0077] Reference is now made to FIG. 4 where there is shown a
process flow 36 according to an embodiment of the present
invention. The process flow 36 begins with start 50 and includes a
rinse 100, a spin 105, a clean with first solution 110, a spin 115,
a rinse 120, a spin 125, a clean with second solution 130, a spin
135, a rinse 140, a spin 145, an electroless plating 150 and is
completed with end 175. For process flow 36, the clean with first
solution 110, the spin 115, the rinse 120, the spin 125, the clean
with second solution 130, the spin 135, the rinse 140, the spin
145, and the electroless plating 150 are essentially the same as
described above.
[0078] The rinse 100 includes wetting the surface of the substrate
with deionized water or deionized water having one or more
surfactant(s). The deionized water or the deionized water having
one or more surfactants is exposed to the substrate so as to wet
substantially the entire surface of the substrate to be subjected
to a first cleaning solution.
[0079] The spin 105 includes spinning the substrate at a velocity
sufficient to reduce the amount of the deionized water or the
deionized water having one or more surfactants used for the rinse
100, i.e., spinning off excess liquid. For preferred embodiments,
excess liquid on the surface of the substrate is removed
substantially without dewetting or drying the substrate.
[0080] Preferred embodiments of process flow 36 include using a
first cleaning solution such as first cleaning solutions shown in
TABLE 3 and a second cleaning solution such as second cleaning
solutions shown in TABLE 4. In more preferred embodiments, process
flow 34 uses a first cleaning solution such as cleaning solutions
identified above as (b), (c), (d), (e), (f), (g), (h), (i), (j),
(k), and (l) and uses a second cleaning solution such as cleaning
solutions identified above as (b), (c), (d), (g), (h), (i), (j),
(k), (l), (m), and (n).
[0081] Reference is now made to FIG. 5 where there is shown a
process flow 38 according to an embodiment of the present
invention. The process flow 38 begins with start 50 and includes a
clean with first solution 110, a spin 115, a rinse 120, a spin 125,
a clean with second solution 130, a spin 135, an electroless
plating 150 and is completed with end 175. For process flow 38, the
clean with first solution 110, the spin 115, the rinse 120, the
spin 125, the clean with second solution 130, the spin 135, and the
electroless plating 150 are essentially the same as described
above. Preferred embodiments of process flow 38 include using a
first cleaning solution such as first cleaning solutions shown in
TABLE 3 and a second cleaning solution such as second cleaning
solutions shown in TABLE 4. In more preferred embodiments, process
flow 38 uses a first cleaning solution such as cleaning solutions
identified above as (b), (c), (d), (e), (f), (g), (h), (i), (j),
(k), and (l) and uses a second cleaning solution such as cleaning
solutions identified above as (m) and (n).
[0082] Reference is now made to FIG. 6 where there is shown a
process flow 40 according to an embodiment of the present
invention. The process flow 40 begins with start 50 and includes a
rinse 100, a spin 105, a clean with first solution 110, a spin 115,
a rinse 120, a spin 125, a clean with second solution 130, a spin
135, an electroless plating 150 and is completed with end 175. For
process flow 40, the rinse 100, the spin 105, the clean with first
solution 110, the spin 115, the rinse 120, the spin 125, the clean
with second solution 130, the spin 135, and the electroless plating
150 are essentially the same as described above. Preferred
embodiments of process flow 40 include using a first cleaning
solution such as first cleaning solutions shown in TABLE 3 and a
second cleaning solution such as second cleaning solutions shown in
TABLE 4. More preferably, embodiments of process flow 40 use a
first cleaning solution such as cleaning solutions identified above
as (b), (c), (d), (e), (f), (g), (h), (i), (j), (k), and (l) and
uses a second cleaning solution such as cleaning solutions
identified above as (m) and (n).
[0083] Reference is now made to FIG. 7 where there is shown a
process flow 41-1 according to an embodiment of the present
invention. The process flow 41-1 begins with start 50 and includes
a clean with first solution 110, a spin 115, a clean with second
solution 130, a spin 135, a rinse 140, a spin 145, an electroless
plating 150 and is completed with end 175. For process flow 41-1,
the clean with first solution 110, the spin 115, the clean with
second solution 130, the spin 135, the rinse 140, the spin 145, and
the electroless plating 150 are essentially the same as described
above. Preferred embodiments of process flow 41-1 include using a
first cleaning solution such as preferred first cleaning solutions
shown in TABLE 3 and a second cleaning solution such as preferred
second cleaning solutions shown in TABLE 4. More preferably,
embodiments of process flow 41-1 use a first cleaning solution such
as cleaning solutions identified above as (b), (c), (d), (e), (f),
(g), (h), (i), (j), (k), and (l) and uses a second cleaning
solution such as cleaning solutions identified above as (b), (c),
(d), (g), (h), (i), (j), (k), (l), (m), and (n).
[0084] Reference is now made to FIG. 8 where there is shown a
process flow 41-2 according to an embodiment of the present
invention. The process flow 41-2 begins with start 50 and includes
a rinse 100, a spin 105, a clean with first solution 110, a spin
115, a clean with second solution 130, a spin 135, a rinse 140, a
spin 145, an electroless plating 150 and is completed with end 175.
For process flow 41-2, the rinse 100, the spin 105, the clean with
first solution 110, the spin 115, the clean with second solution
130, the spin 135, the rinse 140, the spin 145, and the electroless
plating 150 are essentially the same as described above. Preferred
embodiments of process flow 41-2 include using a first cleaning
solution such as first cleaning solutions shown in TABLE 3 and a
second cleaning solution such as second cleaning solutions shown in
TABLE 4. More preferably, embodiments of process flow 41-2 use a
first cleaning solution such as cleaning solutions identified above
as (b), (c), (d), (e), (f), (g), (h), (i), (j), (k), and (l) and
uses a second cleaning solution such as cleaning solutions
identified above as (b), (c), (d), (g), (h), (i), (j), (k), (l),
(m), and (n).
[0085] Reference is now made to FIG. 9 where there is shown a
process flow 41-3 according to an embodiment of the present
invention. The process flow 41-3 begins with start 50 and includes
a clean with first solution 110, a spin 115, a clean with second
solution 130, a spin 135, an electroless plating 150 and is
completed with end 175. For process flow 41-3, the clean with first
solution 110, the spin 115, the clean with second solution 130, the
spin 135, and the electroless plating 150 are essentially the same
as described above. Preferred embodiments of process flow 41-3
include using a first cleaning solution such as first cleaning
solutions shown in TABLE 3 and a second cleaning solution such as
second cleaning solutions shown in TABLE 4. More preferably,
embodiments of process flow 41-3 use a first cleaning solution such
as cleaning solutions identified above as (b), (c), (d), (e), (f),
(g), (h), (i), (j), (k), and (l) and uses a second cleaning
solution such as cleaning solutions identified above as (m) and
(n).
[0086] Reference is now made to FIG. 10 where there is shown a
process flow 41-4 according to an embodiment of the present
invention. The process flow 41-4 begins with start 50 and includes
a rinse 100, a spin 105, a clean with first solution 110, a spin
115, a clean with second solution 130, a spin 135, an electroless
plating 150 and is completed with end 175. For process flow 41-4,
the rinse 100, the spin 105, the clean with first solution 110, the
spin 115, the clean with second solution 130, the spin 135, and the
electroless plating 150 are essentially the same as described
above. Preferred embodiments of process flow 41-4 include using a
first cleaning solution such as first cleaning solutions shown in
TABLE 3 and a second cleaning solution such as second cleaning
solutions shown in TABLE 4. More preferably, embodiments of process
flow 41-4 use a first cleaning solution such as cleaning solutions
identified above as (b), (c), (d), (e), (f), (g), (h), (i), (j),
(k), and (l) and uses a second cleaning solution such as cleaning
solutions identified above as (m) and (n).
[0087] Reference is now made to FIG. 11 where there is shown a
process flow 42-1 according to an embodiment of the present
invention. The process flow 42-1 begins with start 50 and includes
a clean with first solution 110, a rinse 120, a spin 125, a clean
with second solution 130, a rinse 140, a spin 145, an electroless
plating 150 and is completed with end 175. For process flow 42-1,
the clean with first solution 110, the rinse 120, the spin 125, the
clean with second solution 130, the rinse 140, the spin 145, the
electroless plating 150 are essentially the same as described
above. Preferred embodiments of process flow 42-1 include using a
first cleaning solution such as first cleaning solutions shown in
TABLE 3 and a second cleaning solution such as second cleaning
solutions shown in TABLE 4. In more preferred embodiments, process
flow 42-1 uses a first cleaning solution such as cleaning solutions
identified above as (b), (c), (d), (e), (f), (g), (h), (i), (j),
(k), and (l) and uses a second cleaning solution such as cleaning
solutions identified above as (b), (c), (d), (g), (h), (i), (j),
(k), (l), (m), and (n).
[0088] Reference is now made to FIG. 12 where there is shown a
process flow 42-2 according to an embodiment of the present
invention. The process flow 42-2 begins with start 50 and includes
a rinse 100, a spin 105, a clean with first solution 110, a rinse
120, a spin 125, a clean with second solution 130, a rinse 140, a
spin 145, an electroless plating 150 and is completed with end 175.
For process flow 42-2, the rinse 100, the spin 105, the clean with
first solution 110, the rinse 120, the spin 125, the clean with
second solution 130, the rinse 140, the spin 145, the electroless
plating 150 are essentially the same as described above. Preferred
embodiments of process flow 42-2 include using a first cleaning
solution such as first cleaning solutions shown in TABLE 3 and a
second cleaning solution such as second cleaning solutions shown in
TABLE 4. In more preferred embodiments, process flow 42-2 uses a
first cleaning solution such as cleaning solutions identified above
as (b), (c), (d), (e), (f), (g), (h), (i), (j), (k), and (l) and
uses a second cleaning solution such as cleaning solutions
identified above as (b), (c), (d), (g), (h), (i), (j), (k), (l),
(m), and (n).
[0089] Reference is now made to FIG. 13 where there is shown a
process flow 43-1 according to an embodiment of the present
invention. The process flow 43-1 begins with start 50 and includes
a clean with first solution 110, a rinse 120, a spin 125, a clean
with second solution 130, a spin 135, an electroless plating 150
and is completed with end 175. For process flow 43-1, the clean
with first solution 110, the rinse 120, the spin 125, the clean
with second solution 130, the spin 135, the electroless plating 150
are essentially the same as described above. Preferred embodiments
of process flow 43-1 include using a first cleaning solution such
as first cleaning solutions shown in TABLE 3 and a second cleaning
solution such as second cleaning solutions shown in TABLE 4. In
more preferred embodiments, process flow 43-1 uses a first cleaning
solution such as cleaning solutions identified above as (b), (c),
(d), (e), (f), (g), (h), (i), (j), (k), and (l) and uses a second
cleaning solution such as cleaning solutions identified above as
(m) and (n).
[0090] Reference is now made to FIG. 14 where there is shown a
process flow 43-2 according to an embodiment of the present
invention. The process flow 43-2 begins with start 50 and includes
a rinse 100, a spin 105, a clean with first solution 110, a rinse
120, a spin 125, a clean with second solution 130, a spin 135, an
electroless plating 150 and is completed with end 175. For process
flow 43-2, the rinse 100, the spin 105, the clean with first
solution 110, the rinse 120, the spin 125, the clean with second
solution 130, the spin 135, and the electroless plating 150 are
essentially the same as described above. Preferred embodiments of
process flow 43-2 include using a first cleaning solution such as
first cleaning solutions shown in TABLE 3 and a second cleaning
solution such as second cleaning solutions shown in TABLE 4. In
more preferred embodiments, process flow 43-2 uses a first cleaning
solution such as cleaning solutions identified above as (b), (c),
(d), (e), (f), (g), (h), (i), (j), (k), and (l) and uses a second
cleaning solution such as cleaning solutions identified above as
(m) and (n).
[0091] Reference is now made to FIG. 15 where there is shown a
process flow 44-1 according to an embodiment of the present
invention. The process flow 44-1 begins with start 50 and includes
a clean with first solution 110, a clean with second solution 130,
a spin 135, a rinse 140, a spin 145, an electroless plating 150 and
is completed with end 175. For process flow 44-1, the clean with
first solution 110, the clean with second solution 130, the spin
135, the rinse 140, the spin 145, and the electroless plating 150
are essentially the same as described above. Preferred embodiments
of process flow 44-1 include using a first cleaning solution such
as first cleaning solutions shown in TABLE 3 and a second cleaning
solution such as second cleaning solutions shown in TABLE 4. In
more preferred embodiments, process flow 44-1 uses a first cleaning
solution such as cleaning solutions identified above as (b), (c),
(d), (e), (f), (g), (h), (i), (j), (k), and (l) and uses a second
cleaning solution such as cleaning solutions identified above as
(b), (c), (d), (g), (h), (i), (j), (k), (l), (m), and (n).
[0092] Reference is now made to FIG. 16 where there is shown a
process flow 44-2 according to an embodiment of the present
invention. The process flow 44-2 begins with start 50 and includes
a rinse 100, a spin 105, a clean with first solution 110, a clean
with second solution 130, a spin 135, a rinse 140, a spin 145, an
electroless plating 150 and is completed with end 175. For process
flow 44-2, the rinse 100, the spin 105, the clean with first
solution 110, the clean with second solution 130, the spin 135, the
rinse 140, the spin 145, and the electroless plating 150 are
essentially the same as described above. Preferred embodiments of
process flow 44-2 include using a first cleaning solution such as
first cleaning solutions shown in TABLE 3 and a second cleaning
solution such as second cleaning solutions shown in TABLE 4. In
more preferred embodiments, process flow 44-2 uses a first cleaning
solution such as cleaning solutions identified above as (b), (c),
(d), (e), (f), (g), (h), (i), (j), (k), and (l) and uses a second
cleaning solution such as cleaning solutions identified above as
(b), (c), (d), (g), (h), (i), (j), (k), (l), (m), and (n).
[0093] Reference is now made to FIG. 17 where there is shown a
process flow 45-1 according to an embodiment of the present
invention. The process flow 45-1 begins with start 50 and includes
a clean with first solution 110, a clean with second solution 130,
a spin 135, an electroless plating 150 and is completed with end
175. For process flow 45-1, the clean with first solution 110, the
clean with second solution 130, the spin 135, and the electroless
plating 150 are essentially the same as described above. Preferred
embodiments of process flow 45-1 include using a first cleaning
solution such as first cleaning solutions shown in TABLE 3 and a
second cleaning solution such as second cleaning solutions shown in
TABLE 4. In more preferred embodiments, process flow 45-1 uses a
first cleaning solution such as cleaning solutions identified above
as (b), (c), (d), (e), (f), (g), (h), (i), (j), (k), and (l) and
uses a second cleaning solution such as cleaning solutions
identified above as (m) and (n).
[0094] Reference is now made to FIG. 18 where there is shown a
process flow 45-2 according to an embodiment of the present
invention. The process flow 45-2 begins with start 50 and includes
a rinse 100, a spin 105, a clean with first solution 110, a clean
with second solution 130, a spin 135, an electroless plating 150
and is completed with end 175. For process flow 45-2, the rinse
100, the spin 105, the clean with first solution 110, the clean
with second solution 130, the spin 135, and the electroless plating
150 are essentially the same as described above. Preferred
embodiments of process flow 45-2 include using a first cleaning
solution such as first cleaning solutions shown in TABLE 3 and a
second cleaning solution such as second cleaning solutions shown in
TABLE 4. In more preferred embodiments, process flow 45-2 uses a
first cleaning solution such as cleaning solutions identified above
as (b), (c), (d), (e), (f), (g), (h), (i), (j), (k), and (l) and
uses a second cleaning solution such as cleaning solutions
identified above as (m) and (n).
[0095] Reference is now made to FIG. 19 where there is shown a
process flow 46-1 according to an embodiment of the present
invention. The process flow 46-1 begins with start 50, includes a
clean with single solution 108, a spin 117, a rinse 120, a spin
125, an electroless plating 150, and is completed with end 175. For
process flow 46-1, the rinse 120, the spin 125, and the electroless
plating 150 are essentially the same as described above. The clean
with single solution 108 includes exposing a cleaning solution to
the surface of the substrate so that the substrate is wetted by the
cleaning solution under conditions suitable for cleaning the
substrate. The spin 117 includes spinning the substrate so as to
remove the cleaning solution, i.e., spinning off excess liquid. For
preferred embodiments, spin 117 is done substantially without
dewetting or drying the substrate. Preferred embodiments of process
flow 46-1 include using a single cleaning solution such as single
cleaning solutions shown in TABLE 2. More preferably, process flow
46-1 uses a single cleaning solution such as cleaning solutions
identified above as (b), (c), (f), (g), (h), (i), (j), (k), (l),
(m), and (n).
[0096] Reference is now made to FIG. 20 where there is shown a
process flow 46-2 according to an embodiment of the present
invention. The process flow 46-2 begins with start 50, includes a
rinse 100, a spin 105, a clean with single solution 108, a spin
117, a rinse 120, a spin 125, an electroless plating 150, and is
completed with end 175. For process flow 46-2, the rinse 100, the
spin 105, the clean with single solution 108, the spin 117, the
rinse 120, the spin 125, and the electroless plating 150 are
essentially the same as described above. Preferred embodiments of
process flow 46-2 include using a single cleaning solution such as
single cleaning solutions shown in TABLE 2. More preferably,
process flow 46-2 uses a single cleaning solution such as cleaning
solutions identified above as (b), (c), (f), (g), (h), (i), (j),
(k), (l), (m), and (n).
[0097] According to preferred embodiments of the present invention
the temperature for the substrate cleaning is accomplished using
temperatures that are preferably in the range from about 10.degree.
C. to about 90.degree. C. Preferably the temperature of the
cleaning solution is controlled. As an option, the temperature of
the substrate may be controlled.
[0098] As presented supra, numerous cleaning solution compositions
are suitable for embodiments of the present invention. According to
a preferred embodiment of the present invention the cleaning the of
substrate is performed using cleaning solution compositions
described supra and the concentration of dissolved oxygen in the
cleaning solution is maintained at less than about 5 parts per
million. This means that for any of the selected cleaning solutions
for embodiments of the present invention, it is preferred that the
dissolved oxygen concentration in the cleaning solution is
maintained at less than about 5 part per million when cleaning the
substrate.
[0099] According to preferred embodiments, the process flows shown
in FIG. 1 through FIG. 20 are conducted with the substrate
continuously wetted from start 50 until end 175. In other words,
there are no drying or dewetting steps included in the process
flows. Such embodiments are particularly beneficial for
applications where the substrate cleaning and the electroless
deposition occur in the same process chamber. However, the present
invention is not limited to such preferred embodiments; other
embodiments of the process flows shown in FIG. 1 through FIG. 20
can include one or more drying or dewetting steps. The inclusion of
drying or dewetting steps in the process flows shown in FIG. 1
through FIG. 20 can be beneficial for applications where the
substrate cleaning occurs in one chamber and the substrate is
removed to another chamber for the electroless deposition
[0100] Preferably, the process flows shown in FIG. 1 through FIG.
20 are done in a controlled-ambient environment to limit exposure
of the substrate and process liquids to oxygen. Suitable
controlled-ambient environments have been described in the patent
literature, for example see US 2007/0292603 to Dordi et al., the
contents of which are incorporated herein by this reference. As one
option, the controlled-ambient environment is an integrated system
having at least one process module configured for cleaning the
substrate and at least one other process module configured for
electroless deposition of the cap layer. The system further
includes at least one transfer module coupled to the at least one
process module and to the at least one other process module. The at
least one transfer module is configured so that the substrate can
be transferred between the modules substantially without exposure
to an oxide-forming environment. Alternatively, the integrated
system may include one process module for both cleaning the
substrate and the electroless deposition and at least one transfer
module coupled to the process module.
[0101] In the foregoing specification, the invention has been
described with reference to specific embodiments. However, one of
ordinary skill in the art appreciates that various modifications
and changes can be made without departing from the scope of the
present invention as set forth in the claims below. Accordingly,
the specification and figures are to be regarded in an illustrative
rather than a restrictive sense, and all such modifications are
intended to be included within the scope of the present
invention.
[0102] Benefits, other advantages, and solutions to problems have
been described above with regard to specific embodiments. However,
the benefits, advantages, solutions to problems, and any element(s)
that may cause any benefit, advantage, or solution to occur or
become more pronounced are not to be construed as a critical,
required, or essential feature or element of any or all the
claims.
[0103] As used herein, the terms "comprises," "comprising,"
"includes," "including," "has," "having," "at least one of," or any
other variation thereof, are intended to cover a non-exclusive
inclusion. For example, a process, method, article, or apparatus
that comprises a list of elements is not necessarily limited only
to those elements but may include other elements not expressly
listed or inherent to such process, method, article, or apparatus.
Further, unless expressly stated to the contrary, "or" refers to an
inclusive or and not to an exclusive or. For example, a condition A
or B is satisfied by any one of the following: A is true (or
present) and B is false (or not present), A is false (or not
present) and B is true (or present), and both A and B are true (or
present).
TABLE-US-00001 TABLE 1 * ID pH I II III IV V VI VII VIII IX (a) P
(b) >0.5 and <2.5 P P P O (c) >2.5 and <5 P P P O O (d)
>5 and <8 P P P O O O O (e) >8 and <13 P P P O O O O
(f) <2.5 P O O O (g) >0.5 and <2.5 P P P O P (h) >2.5
and <5 P P P O O P (i) >5 and <8 P P P O O O O P (j) >8
and <13 P P P O O O O P (k) <2.5 P O O O P (l) <2.5 P O O
P (m) >1 and <6 P P O O (n) >1 and <6 P O O O *
I-Hydroxycarboxylic acid(s) or Non-alkali metal salt(s) of
hydroxycarboxylic acid(s) II-Surfactant(s) III-Reducing agent(s)
IV-pH adjustor(s) V-Complexing agent(s) for Cu(I) VI-Corrosion
inhibitor(s) VII-Oxygen scavenger(s) VIII-Fluoride compound(s)
IX-Oxidizer(s) P-Present in the solution O-Optionally present in
the solution
TABLE-US-00002 TABLE 2 Single Cleaning Solutions* ID pH I II III IV
V VI VII VIII IX (a) P (b) >0.5 and <2.5 P P P O (c) >2.5
and <5 P P P O O (f) <2.5 P O O O (g) >0.5 and <2.5 P P
P O P (h) >2.5 and <5 P P P O O P (i) >5 and <8 P P P O
O O O P (j) >8 and <13 P P P O O O O P (k) <2.5 P O O O P
(l) <2.5 P O O P (m) >1 and <6 P P O O (n) >1 and <6
P O O O * I-Hydroxycarboxylic acid(s) or Non-alkali metal salt(s)
of hydroxycarboxylic acid(s) II-Surfactant(s) III-Reducing agent(s)
IV-pH adjustor(s) V-Complexing agent(s) for Cu(I) VI-Corrosion
inhibitor(s) VII-Oxygen scavenger(s) VIII-Fluoride compound(s)
IX-Oxidizer(s) P-Present in the solution O-Optionally present in
the solution
TABLE-US-00003 TABLE 3 First Cleaning Solutions* ID pH I II III IV
V VI VII VIII IX (a) P (b) >0.5 and <2.5 P P P O (c) >2.5
and <5 P P P O O (d) >5 and <8 P P P O O O O (e) >8 and
<13 P P P O O O O (f) <2.5 P O O O (g) >0.5 and <2.5 P
P P O P (h) >2.5 and <5 P P P O O P (i) >5 and <8 P P P
O O O O P (j) >8 and <13 P P P O O O O P (k) <2.5 P O O O
P (l) <2.5 P O O P * I-Hydroxycarboxylic acid(s) or Non-alkali
metal salt(s) of hydroxycarboxylic acid(s) II-Surfactant(s)
III-Reducing agent(s) IV-pH adjustor(s) V-Complexing agent(s) for
Cu(I) VI-Corrosion inhibitor(s) VII-Oxygen scavenger(s)
VIII-Fluoride compound(s) IX-Oxidizer(s) P-Present in the solution
O-Optionally present in the solution
TABLE-US-00004 TABLE 4 Second Cleaning Solutions* ID pH I II III IV
V VI VII VIII IX (a) P (b) >0.5 and <2.5 P P P O (c) >2.5
and <5 P P P O O (d) >5 and <8 P P P O O O O (g) >0.5
and <2.5 P P P O P (h) >2.5 and <5 P P P O O P (i) >5
and <8 P P P O O O O P (j) >8 and <13 P P P O O O O P (k)
<2.5 P O O O P (m) >1 and <6 P P O O (n) >1 and <6 P
O O O * I-Hydroxycarboxylic acid(s) or Non-alkali metal salt(s) of
hydroxycarboxylic acid(s) II-Surfactant(s) III-Reducing agent(s)
IV-pH adjustor(s) V-Complexing agent(s) for Cu(I) VI-Corrosion
inhibitor(s) VII-Oxygen scavenger(s) VIII-Fluoride compound(s)
IX-Oxidizer(s) P-Present in the solution O-Optionally present in
the solution
* * * * *