U.S. patent application number 11/603196 was filed with the patent office on 2007-04-05 for cleaning method of treatment equipment and treatment equipment.
This patent application is currently assigned to TOKYO ELECTRON LIMITED. Invention is credited to Yasuhiko Kojima, Yasuhiro Oshima.
Application Number | 20070074739 11/603196 |
Document ID | / |
Family ID | 18586959 |
Filed Date | 2007-04-05 |
United States Patent
Application |
20070074739 |
Kind Code |
A1 |
Kojima; Yasuhiko ; et
al. |
April 5, 2007 |
Cleaning method of treatment equipment and treatment equipment
Abstract
In a state of the inside of a treatment chamber of treatment
equipment being evacuated, therein a cleaning gas containing
trifluoroacetic acid (TFA) as a cleaning agent is supplied. Metal
such as copper used in the formation of an interconnection or an
electrode and stuck on an inner wall surface of the treatment
chamber, when coming into contact with the cleaning agent (TFA) in
the cleaning gas, without forming an oxide or a metallic salt, is
directly complexed. The complex is sublimed due to the evacuation
and is exhausted outside the treatment chamber. Accordingly, at
less labor and low cost, the cleaning can be efficiently
implemented.
Inventors: |
Kojima; Yasuhiko;
(Nirasaki-shi, JP) ; Oshima; Yasuhiro;
(Nirasaki-shi, JP) |
Correspondence
Address: |
PILLSBURY WINTHROP SHAW PITTMAN, LLP
P.O. BOX 10500
MCLEAN
VA
22102
US
|
Assignee: |
TOKYO ELECTRON LIMITED
Tokyo
JP
|
Family ID: |
18586959 |
Appl. No.: |
11/603196 |
Filed: |
November 22, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09801825 |
Mar 9, 2001 |
7172657 |
|
|
11603196 |
Nov 22, 2006 |
|
|
|
Current U.S.
Class: |
134/2 ; 118/715;
134/3; 134/42 |
Current CPC
Class: |
C23C 16/4405
20130101 |
Class at
Publication: |
134/002 ;
134/003; 134/042; 118/715 |
International
Class: |
C23G 1/02 20060101
C23G001/02; B08B 9/00 20060101 B08B009/00; C23G 1/00 20060101
C23G001/00; B08B 7/00 20060101 B08B007/00; C23C 16/00 20060101
C23C016/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 10, 2000 |
JP |
2000-67827 |
Claims
1-10. (canceled)
11. A treatment apparatus, comprising: a chamber; a susceptor
mounting a substrate in the chamber; a first source supplying a
treatment agent containing a metal for forming a metal film on the
substrate; a second source supplying a cleaning agent containing
one of a carboxylic acid and a derivative of a carboxylic acid for
reacting a metal film on an inner wall of the chamber to form a
metal complex of the metal and the cleaning agent; a vaporizer
vaporizing the treatment agent and the cleaning agent; a first pipe
supplying the treatment agent from the first source to the
vaporizer; a second pipe supplying the cleaning agent from the
second source to the vaporizer; a third pipe supplying the
vaporized treatment agent and the vaporized cleaning agent from the
vaporizer to the chamber; a heater heating the chamber, the third
pipe, and the vaporizer; and a vacuum pump exhausting the chamber,
wherein the metal film is formed on the inner wall of the chamber
by the vaporized treatment agent and the metal film on the inner
wall is cleaned by the vaporized cleaning agent.
12-16. (canceled)
17. The treatment apparatus of claim 11, wherein the one of the
carboxylic acid and the derivative comprises a compound selected
from the group comprising RCOOH, RCOOR', and R(COOH).sub.n, R, R'
are hydrocarbon group containing halogen atom, and n is an
integer.
18. The treatment apparatus of claim 11, wherein the carboxylic
acid comprises trifluoroacetic acid.
19. The treatment apparatus of claim 11, wherein the metal is
copper.
20. The treatment apparatus of claim 11, further comprising a
supply unit for supplying an additive to promote formation of the
metal complex.
21. The treatment apparatus of claim 20, wherein the additive
includes oxygen or water vapor.
22. The treatment apparatus of claim 11, wherein the treatment
agent contains CU.sup.+1 (hexafluoroacetylacetonate) and silyl
olefin ligand.
23. The treatment apparatus of claim 11, wherein the heater heats
the susceptor.
24. The treatment apparatus of claim 11, further comprising a drain
exhausting the third pipe.
25. The treatment apparatus of claim 11, further comprising a
shower head supplying the vaporized treatment agent and the
vaporized treatment agent from the third pipe into the chamber.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a cleaning method of
cleaning equipment, in particular to a cleaning method for removing
metal or the like stuck to an inner wall of a treatment chamber of
the treatment equipment and treatment equipment enabling such
cleaning.
[0003] 2. Description of the Related Art
[0004] When depositing, by the use of treatment equipment such as
Chemical Vapor Deposition (CVD) equipment or the like, a thin metal
film on a Si wafer (hereafter refer to as "wafer"), after
accommodating the wafer in the treatment chamber, a treatment gas
is supplied. The treatment gas contains various kinds of metals
such as copper, the metal segregating in thin film on the
wafer.
[0005] When the treatment gas sticks on an inner wall of the
treatment chamber, also on the inner wall surface of the treatment
chamber, a thin metal film is formed. The thin film stuck on the
inner wall surface of the treatment chamber, when being left as it
is, may cause problems when treating the wafer. Accordingly, it is
necessary to implement periodical cleaning of the treatment chamber
to remove the thin metal film stuck on the inner wall surface.
[0006] When the thin metal film is composed of metal difficult to
ionize such as copper or the like, it can be removed with
difficulty. Accordingly, in the treatment chamber to which the thin
metal film such as copper or the like sticks, an oxidizing agent is
supplied to oxidize copper to copper oxide. Thereafter, the copper
oxide is removed to clean the inside of the treatment chamber.
[0007] For instance, in Japanese Patent Publication No.
JP-A-11-140652, the following cleaning method of treatment
equipment is disclosed: [0008] (1) First, metal stuck on a
treatment chamber wall is oxidized to form metal oxide. [0009] (2)
Then, the oxide is transformed to a metal complex. [0010] (3)
Thereafter, the inside of the treatment chamber is evacuated to
sublime the metal complex.
[0011] Thus by implementing the processes of oxidizing, complexing
and subliming, the thin metal film stuck on the inner wall surface
of the treatment chamber is removed.
[0012] In the method, however, three steps are required to increase
a total number of steps, resulting in problems.
[0013] In addition, in the above method, .beta.-diketone is
employed in the complexing step. The .beta.-diketone, being
expensive, pushes up material costs in cleaning.
[0014] In addition, in the above method, since the step of
oxidizing is included, oxygen may remain in the treatment chamber.
Accordingly, due to the remaining oxygen, the treatment chamber may
be caused to deteriorate or the wafer may be adversely
affected.
SUMMARY OF THE INVENTION
[0015] An object of the present invention is to provide a cleaning
method capable of efficiently cleaning treatment equipment with a
small number of steps and treatment equipment furnished with a
cleaning mechanism capable of implementing such cleaning.
[0016] Furthermore, another object of the present invention is to
provide a cleaning method capable of efficiently cleaning treatment
equipment without employing expensive cleaning material and at low
cost and treatment equipment provided with a cleaning mechanism
capable of implementing such cleaning.
[0017] Furthermore, still another object of the present invention
is to provide a cleaning method in which treatment capability of
treatment equipment does not deteriorate after the treatment or
quality of a treated wafer does not fluctuate and treatment
equipment furnished with a cleaning mechanism capable of
implementing such cleaning.
[0018] (1) In order to accomplish the above object, a cleaning
method of the present invention comprises a step off while
supplying a cleaning gas in a treatment chamber of treatment
equipment that treat a substrate, exhausting the cleaning gas from
the treatment chamber. Here, the cleaning gas including a substance
that directly complexes a prescribed metal.
[0019] According to the present invention, the cleaning step is
implemented by the use of a cleaning gas including a substance that
directly complexes metal forming electrode or interconnection. As a
result, upon supply of the cleaning gas in the treatment chamber,
metal stuck on the inner wall surface of the chamber is shortly
complexed. The complexed metal is removed, due to evacuation, from
the treatment chamber together with the cleaning gas. Accordingly,
the number of steps when cleaning is small and cleaning can be
shortly implemented without complexity.
[0020] In addition, there is no step of oxidizing metal stuck on
the inside wall of the treatment chamber. Accordingly, there is no
possibility for the remaining oxygen to be adversely affected.
[0021] "The prescribed metal" means metal to use in the formation
of electrode or interconnection of a semiconductor device, for
instance copper, aluminum, gold, silver or the like being cited.
The above cleaning method is particularly effective in removing
metal difficult to ionize such as copper.
[0022] Furthermore, "substance that directly complexes metal" means
a substance that, without requiring a particular additional step of
forming metal oxide or metallic salt by the use of an oxidizing gas
or the like, directly reacts with the metal to form a complex. As
the example of the "substance that directly complexes metal",
carboxylic acid and carboxylic acid derivatives can be cited.
[0023] Specifically, substances expressed by for instance RCOOH,
RCOOR', or R(COOH).sub.n (R and R' denote hydrocarbon group that
may contain halogen atom, n being an integer number) can be cited,
more specifically trifluoroacetic acid (TFA) being preferable.
[0024] By the use of less expensive material such as organic
carboxylic acid or the like such as TFA as a cleaning agent, the
material cost in cleaning is not pushed up, resulting in less
expensive cleaning.
[0025] As examples of "treatment equipment", film forming equipment
such as Chemical Vapor Deposition (CVD) equipment, Physical Vapor
Deposition (PVD) equipment, and plating equipment, or etching
equipment, Chemical Mechanical Polishing (CMP) equipment can be
cited.
[0026] An additive for promoting the complexing of the prescribed
metal may be contained in the above cleaning gas.
[0027] Due to the addition of the additive, the complexing reaction
is promoted to shorten the time for cleaning. As the additive,
water vapor can be used for instance.
[0028] (2) Another cleaning method of the present invention
comprises the steps of supplying a cleaning gas and of exhausting
the cleaning gas. In the step of supplying a cleaning gas, a
cleaning gas containing a substance that directly complexes
prescribed metal is supplied into a treatment chamber of treatment
equipment for treating a substrate. In the step of exhausting the
cleaning gas, the cleaning gas is exhausted from the treatment
chamber.
[0029] There is not a step of oxidizing the metal stuck onto the
inner wall surface of the treatment chamber. Accordingly, cleaning
can be shortly carried out without difficulty. There is not a
possibility that remaining oxygen adversely affects. Furthermore,
the complexing and exhausting each are completely done, resulting
in efficient cleaning.
[0030] In the above method, the supplying step and the exhausting
step may be alternately repeated. Thereby, the treatment chamber
can be assuredly cleaned.
[0031] (3) Treatment equipment of the present invention comprises a
treatment chamber, a susceptor, a treatment gas supply system, an
evacuating system and a TFA supply system. In the treatment
chamber, a substrate is treated. The susceptor is disposed in the
treatment chamber, on the susceptor the substrate being disposed.
The treatment gas supply system supplies a treatment gas containing
copper as a component in the treatment chamber. The evacuating
system evacuates the inside of the treatment chamber. The TFA
supply system supplies trifluoroacetic acid in the treatment
chamber.
[0032] The treatment equipment of the present invention, being
furnished with the TFA supply system in the treatment chamber to
supply trifluoroacetic acid (TFA), can implement cleaning by a
small number of steps, at low cost and without damaging the
treatment equipment.
[0033] In the aforementioned treatment equipment, as the treatment
gas supply system, for instance one that comprises a treatment
agent tank, treatment gas supply piping connecting the treatment
chamber and the treatment agent tank, and a treatment agent
vaporizer disposed in the middle of the treatment gas supply piping
can be cited.
[0034] Furthermore, as the TFA supply system, for instance one that
comprises a TFA tank and TFA supply piping connecting the TFA tank
and the treatment gas supply piping downstream the treatment agent
vaporizer in a direction of a gas movement can be cited. As a
result, metal stuck on an inner wall of the treatment gas supply
piping can be cleaned.
[0035] In addition, in the above treatment equipment, it is
preferable to dispose a heater at least in a portion downstream the
vaporizer of the treatment agent supply piping. By heating the
piping by means of the heater, the inside of the piping can be more
efficiently cleaned.
[0036] For instance, in the treatment chamber, a heater for heating
the inner wall of the treatment chamber, for instance a heater
capable of electrically heating such as Nichrome wire or the like
may be built in.
[0037] As the treatment agent tank, a tank containing a treatment
agent essentially consisting of copper can be cited.
[0038] The treatment equipment may comprise a supply system for
supplying an additive that promotes the completing of copper. By
the addition of the additive, the complexing can be promoted to
result in shortening of the cleaning time. The supply system can be
constituted of for instance piping connected to any one of the
treatment chamber, the treatment gas supply piping and the TFA
supply piping.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] FIG. 1 is a vertical section showing an entire configuration
of treatment equipment (CVD equipment) involving the present
invention.
[0040] FIG. 2 is a diagram schematically showing a piping route of
treatment equipment involving the present invention.
[0041] FIG. 3 is a flowchart of a cleaning method involving a first
implementation mode.
[0042] FIG. 4 is a flowchart of a cleaning method involving a
second implementation mode.
[0043] FIG. 5 is a flowchart of a cleaning method involving a third
implementation mode.
[0044] FIG. 6 is one graph showing results of cleaning due to a
second embodiment.
[0045] FIG. 7 is another graph showing results of cleaning due to a
second embodiment.
[0046] FIG. 8 is a graph showing results of cleaning due to a third
embodiment.
DESCRIPTION OF PREFERRED EMBODIMENT
[0047] (1st Mode of Implementation)
[0048] In the following, a cleaning method and treatment equipment
involving a first implementation mode of the present invention will
be explained.
[0049] FIG. 1 is a vertical section showing an entire configuration
of CVD equipment furnished with a cleaning mechanism involving the
present invention.
[0050] As shown in FIG. 1, the treatment equipment 10 comprises a
treatment chamber 1 formed in approximate cylinder from for
instance Al or the like.
[0051] On a ceiling of the treatment chamber 1, a showerhead 13 is
disposed to supply a treatment gas therein. The showerhead 13
comprises a diffusion chamber 13a having a base plate where a
plurality of orifices 13b, 13b and so on are bored. The treatment
gas supplied through a treatment gas supply piping 14 to the
showerhead 13, after diffused once in the diffusion chamber 13a, is
discharged from the orifices 13b, 13b and so on to a wafer W
disposed on a susceptor 2.
[0052] On a sidewall surface in the neighborhood of the ceiling of
the treatment chamber 1, piping 29A and 29B are disposed for
nitrogen and water vapor, respectively. The piping 29A supplies a
nitrogen gas to replace an atmosphere in the treatment chamber when
for instance the wafer W is transferred in and out of the treatment
chamber 1. The piping 29B, as mentioned below, supplies an additive
such as water vapor that promotes a complexing reaction in the
treatment chamber 1.
[0053] Inside the treatment chamber 1, the susceptor 2 for
disposing the wafer W as a substrate to be treated is supported by
a base through a prop 3. As material of the susceptor 2, for
instance graphite, amorphous carbon, composite carbon, and AlN can
be used. Downward the susceptor 2, a lifter pin 4 made of quartz
glass is disposed movable up and down by not shown elevating means.
The lifter pin 4 penetrates a through hole 4A disposed in the
susceptor 2 to hold up the wafer W when transferring in and
out.
[0054] Inside the susceptor 2, a powerful heater 5 consisting of
Nichrome wire or the like is disposed. By means of the heater 5,
the susceptor 2 in the treatment chamber 1 is heated, thereby
indirectly heating the wafer W at a temperature in the range of for
instance from approximate 150 to 300.degree. C. to maintain
there.
[0055] On the sidewall of the treatment chamber 1, a gate valve 11
is disposed to open when transferring the wafer W in and out of the
treatment chamber 1. At a periphery of a base of the treatment
chamber 1, an exhaust 12 connected to a vacuum pump not shown in
the figure is disposed to evacuate the treatment chamber 1.
[0056] FIG. 2 is a diagram schematically showing piping route of
the treatment equipment involving present implementation mode.
[0057] As shown in FIG. 2, to the piping 14A upstream the treatment
gas supply piping 14 connected to the showerhead 13 in the
treatment chamber 1, a treatment agent tank 17 is connected to
receive the treatment agent.
[0058] At an upper portion of the treatment agent tank 17, inert
gas supply piping 18 for supplying an inert gas such as Ar or the
like is disposed together with an opening valve 19. Through the
piping 18, an inert gas such as Ar or the like is supplied into the
treatment agent tank 17. A liquid surface of the treatment agent is
pushed down by the supplied inert gas, thereby the treatment agent
in the treatment agent tank 17 being supplied into the piping
14.
[0059] In the treatment agent tank 17, a treatment agent for
forming a thin film of the metal used for the formation of an
interconnection or an electrode of a semiconductor element, for
instance copper, is accommodated. For instance, precursors
containing copper, in more detail, the following substances can be
cited.
[0060] The treatment agent contains Cu.sup.+1
(hexafluoroacetylacetonate) and silyl olefin ligand.
[0061] The silylolefin ligand is contained in a substance selected
from a group consisting of trimethylvinylsilane (TMVS),
dimethoxymethylvinylsilane (DMOMVS), methoxydimethylvinylsilane
(MODMVS), trimethoxyvinylsilane (TMOVS), triethoxyvinylsilane
(TEOVS), ethoxymethoxymethylvinylsilane (EOMOMVS),
diethoxymethylvinylsilane (DEOMVS), diethoxymethoxyvinylsilane
(DEOMOVS), ethoxydimethoxyvinylsilane (EODMOVS),
ethoxydiethylvinylsilane (EODEVS), diethoxyethylvinylsilane
(DEOEVS), dimethoxyethylvinylsilane (DMOEVS),
ethoxydimethylvinylsilane (EODMVS), methoxydiethylvinylsilane
(MODEVS) and ethylmethoxymethylvinylsilane (EMOMVS).
[0062] In the middle of the piping 14, a liquid massflow controller
15B is disposed, thereby a flow rate of the treatment agent pumped
out of the treatment agent tank 17 being controlled. Upstream the
massflow controller 15B in a direction of movement of the treatment
agent, an opening valve 15C is disposed, downstream the massflow
controller 15B in a direction of movement of the treatment agent an
opening valve 15C being disposed.
[0063] In the middle of the piping 14B connecting the massflow
controller 15B and the opening valve 15C, a branch line 14C is
connected to function as a drain, an opening valve 15D being
disposed thereto. Further downstream the opening valve 15C, a
vaporizer 16 is disposed to vaporize the treatment agent there. The
piping 14D further downstream the vaporizer 16 is connected through
the opening valve 16C to the showerhead 13. In the middle of the
piping 14D, a branch line 14E is connected to function as a drain,
an opening valve 16E being disposed there.
[0064] To the vaporizer 16, another cleaning piping 20 is disposed
independently from the piping 14. As shown in FIG. 2, to piping 20A
upstream the cleaning piping 20 connected to the vaporizer 16, a
cleaning agent tank 21 is connected to accommodate the cleaning
agent such as for instance trifluoroacetic acid (TFA).
[0065] At an upper portion of the cleaning agent tank 21, inert gas
supply piping 22 for supplying an inert gas such as Ar or the like
is disposed together with an opening valve 23. Through the piping
22, the inert gas such as Ar or the like is supplied in the
cleaning agent tank 21. Thereby, a liquid surface of the cleaning
agent is pushed down to supply the cleaning agent in the cleaning
agent tank 21 into the piping 20. In the middle of the piping 20, a
liquid massflow controller 25 is disposed, a flow rate of the
cleaning agent pumped out of the cleaning agent tank 21 being
controlled. Upstream the massflow controller 25 in a direction of
movement of the cleaning agent, an opening valve 24 is disposed. In
addition, downstream the massflow controller 25 in a direction of
movement of the cleaning agent, an opening valve 2.7 is
disposed.
[0066] In the middle of the piping 20B connecting the massflow
controller 25 and the opening valve 27, a branch line 20C is
connected to function as a drain, an opening valve 26 being
disposed to the branch line 20C. Further downstream the opening
valve 27, a branch line 20D is disposed, thereto. 20D an opening
valve 28 being disposed.
[0067] To the vaporizer 16 and the piping 14 downstream the
vaporizer 16, a heater 30 such as a ribbon heater is disposed,
heating the vaporizer 16 and the piping 14 downstream the vaporizer
16 to a prescribed temperature.
[0068] Next, a procedure when cleaning the treatment equipment by
the use of the cleaning method of the present invention will be
explained. FIG. 3 is a flowchart showing a flow when the cleaning
method of the present invention is implemented.
[0069] When cleaning the treatment equipment, first, valves such as
opening valves 19, 15A and 15C are closed to stop supplying the
treatment agent (step S11).
[0070] Then, the heater 30 is turned on to heat the vaporizer 16
and the piping 14 and the treatment chamber 1 downstream the
vaporizer 16 up to for instance 300.degree. C. (step S12)
[0071] Next, the opening valves 23, 24, 27 and 16C are opened and
the massflow controller 25 is turned on to start supplying the
cleaning agent (step S13).
[0072] When the cleaning agent is supplied from the cleaning agent
tank 21 through the piping 20, the cleaning agent is vaporized due
to the operation and heat of the vaporizer 16.
[0073] The vaporized cleaning agent comes into contact with the
inner walls of the vaporizer 16 and the piping 14 and further with
metal such as copper stuck on the inner wall of the treatment
chamber 1. The insides of the vaporizer 16, the piping 14 and the
treatment chamber 1 are heated to sufficiently high temperatures.
Accordingly, the moment when the supplied cleaning agent and the
metal come into contact, a complex is rapidly formed. The metal is,
in the treatment equipment, material for forming the electrode and
the interconnection of a semiconductor element.
[0074] The inside of the treatment chamber 1 is evacuated and
maintained at a reduced pressure. Accordingly, the metal complex
formed as in the above is sublimed and exhausted outside the
treatment chamber 1.
[0075] As explained above, according to the cleaning method
involving the present implementation mode, the treatment equipment
is cleansed by the use of the cleaning gas containing a substance
that directly complexes the metal that forms the electrode or the
interconnection. Accordingly, the cleaning can be simply and
shortly carried out with less labor.
[0076] In addition, due to the use of less expensive substances
such as trifluoroacetic acid (TFA) as used in the above
implementation mode, material cost necessary for cleaning can be
reduced.
[0077] Furthermore, by the use of the treatment equipment furnished
with a mechanism supplying the cleaning agent to the vaporizer of
the treatment gas supply piping as shown in the above
implementation mode, the metal such as copper stuck not only to the
treatment chamber but also to the inside of the treatment gas
supply piping can be cleaned with ease.
[0078] (2nd Implementation Mode)
[0079] In the following, a second implementation mode of the
present invention will be explained. In the following
implementation modes, contents duplicating with the preceding
implementation mode will be omitted from explanation.
[0080] The present implementation mode is configured in two steps
of complexing metal stuck to the inside of the treatment chamber 1
and of subliming the generated complex due to evacuation to
remove.
[0081] FIG. 4 is a flowchart showing treatment steps of the
cleaning method involving the present implementation mode.
[0082] When implementing the cleaning method involving the present
implementation mode, first, as shown in the flowchart of FIG. 3, in
the treatment equipment shown in FIG. 2, the valves such as opening
valves 19, 15A and 15C are closed to stop the supply of the
treatment agent (step S21).
[0083] Next, the heater 30 is turned on to heat the vaporizer 16
and the piping 14 and the treatment chamber 1 downstream the
vaporizer 16 up to a prescribed temperature, for instance
300.degree. C. (step S22).
[0084] Then, the opening valves 23, 24, 27 and 16C are opened and
the massflow controller 25 is turned on to start the supply of the
cleaning agent (step S23).
[0085] Upon supplying the cleaning agent from the cleaning agent
tank 21 through the piping 20, the cleaning agent is vaporized due
to operation and heat of the vaporizer 16. The vaporized cleaning
agent comes into contact with the inner walls of the vaporizer 16
and the piping 14 and further with metal stuck on the inner wall of
the treatment chamber 1. The metal is one such as copper or the
like that is used to form the electrode and the interconnection of
a semiconductor element. At that time, the insides of the vaporizer
16, the piping 14 and the treatment chamber 1 are heated
sufficiently high temperatures. Accordingly, the moment when the
supplied cleaning agent and the metal come into contact, a complex
is rapidly formed.
[0086] After the course of a prescribed time period to sufficiently
complex the metal, the opening valves 23, 24 and 27 are closed to
stop the supply of the cleaning agent.
[0087] Approximately simultaneously with the stoppage of the supply
of the cleaning agent, a vacuum pump is operated to evacuate the
inside of the treatment chamber 1 (step S24).
[0088] By evacuating the treatment chamber 1, the metal complex
generated in the step S23 is sublimed to exhaust outside the
treatment chamber 1.
[0089] As explained above, the cleaning method involving the
present implementation mode is configured in two separate steps of
complexing the metal and subliming the complex generated in the
complexing step. As a result, the steps of complexing and subliming
can be completely implemented, respectively, resulting in a
peculiar effect of improving cleaning efficiency.
[0090] (3rd Implementation Mode)
[0091] In the following, a third implementation mode of the present
invention will be explained.
[0092] The present implementation mode is configured so that the
step of complexing the metal stuck to the treatment chamber and the
step of subliming the generated complex due to the evacuation to
remove are intermittently repeated.
[0093] FIG. 5 is a flowchart of a cleaning method involving the
present implementation mode.
[0094] When implementing the cleaning method involving the present
implementation mode, similarly with the second implementation mode,
after the stoppage of supply of the treatment agent (step S31) and
heating of the vaporizer, the piping and the treatment chamber
(step S32), the cleaning agent is started supplying (step S33).
[0095] After the course of a prescribed time to sufficiently
complex a surface of the metal stuck on the inner wall of the
treatment chamber 1, the cleaning agent'is stopped supplying (step
S34). Then, the evacuation of the treatment chamber is began (step
S35).
[0096] After the course of a prescribed time to sufficiently
sublime the metal complex formed in the step S33 to evacuate
outside the treatment chamber, the evacuation is stopped (step
S36).
[0097] Next, an amount of the metal stuck on the inner wall surface
of the treatment chamber 1 is confirmed (step S37). The
confirmation operation may be implemented by directly observing a
sticking state of metal on the inner wall of the treatment chamber
or may be implemented by confirming a remaining amount of a metal
film formed on a surface of a monitoring wafer W.
[0098] When, in the step S37, the amount of metal stuck on the
inner wall surface of the treatment chamber 1 is confirmed to be
sufficiently reduced, the cleaning is stopped.
[0099] On the contrary, when, in the step S37, the amount of metal
stuck on the inner wall surface of the treatment chamber 1 is not
confirmed to be sufficiently reduced, the operation of the steps
from S33 to S37 are repeated. Thus, up to the complete removal of
the stuck metal, the operation of cleaning is repeated.
[0100] As explained above, according to the cleaning method
involving the present implementation mode, the steps of complexing
the metal and of sublimating the complex formed through the
complexing step are separated in two stages and intermittently
repeated. Accordingly, the complexing and the sublimation can be
completely implemented, resulting in an effect of improving
cleaning efficiency.
[0101] (4th Implementation Mode)
[0102] In the following, a fourth implementation mode of the
present invention will be described.
[0103] In the present implementation mode, in the step of
complexing the metal stuck on the inner wall of the treatment
chamber 1, an additive is added in the cleaning gas to promote the
complexing of the metal. As specific steps, the treatment steps of
FIGS. 3 to 5 explained in the first through third implementation
modes can be applied. That is, in any one of the steps of S13 of
FIG. 3, S23 of FIG. 4 and S33 of FIG. 5, together with the supply
of the cleaning agent, the additive is only necessary to be added.
As the additive for promoting the complexing, water vapor or oxygen
can be used.
[0104] For instance, in the step S13 of FIG. 3, the cleaning agent
(cleaning gas) vaporized in the vaporizer 16 is assumed to be
supplied in the treatment chamber 1. Together with the supply of
the cleaning gas into the treatment chamber 1, from the piping 29B
water vapor is supplied into the treatment chamber 1.
[0105] As a result, the water vapor is added to the cleaning gas.
The cleaning gas comes into contact with the metal such as copper
stuck on the inner wall of the treatment chamber 1 to form complex.
The water vapor that is added to the cleaning gas promotes the
formation of the complex. The complexing of the metal is over in a
short time, resultantly.
[0106] The addition of water vapor or the like to the cleaning gas
is not necessarily implemented through the piping separate from the
piping 14 that supplies the cleaning gas, but can be implemented by
adding water vapor in the middle of the piping 14.
[0107] (Embodiment 1)
[0108] In the following, embodiments of the present invention will
be explained.
[0109] With the treatment equipment explained in the aforementioned
implementation modes, a wafer W on which surface copper of a
thickness of 5000 angstrom is deposited is disposed on the
susceptor 2. Thereafter, an atmosphere in the treatment chamber 1
is replaced by pure nitrogen. The susceptor 2 is heated to
300.degree. C., followed by, through the supply piping 14,
supplying a gas mixture of 35 sccm of TFA diluted by nitrogen. At
that time, the pressure in the treatment chamber 1 is controlled to
be 1.33.times.1.sup.4 Pa (100 Torr). After the state of constant
gas pressure is maintained for 10 min, the gas mixture of TFA and
nitrogen is ceased to supply.
[0110] Thereafter, gas remaining in the treatment chamber 1 is
evacuated, followed by taking out the wafer W.
[0111] From observations of the wafer W by means of a scanning
electron microscope, it is confirmed that the copper on the wafer W
is completely removed by means of the dry cleaning due to TFA.
[0112] (Embodiment 2)
[0113] With samples of the wafer W thereon copper is deposited
similarly with Embodiment 1, the temperature (wafer temperature) of
the susceptor 2 and the gas pressure in the treatment chamber 1 are
varied to investigate an amount of etching of copper.
[0114] As the sample, a wafer W thereon copper is deposited is cut
into squares of 2.times.2 mm to use. Furthermore, as the cleaning
gas, a gas mixture of flow rate 3.7 sccm of TFA and flow rate 40
sccm of nitrogen is used. A constant gas pressure is maintained for
10 min to implement the complexing. After the stoppage of the gas
supply, the evacuation is carried out to sublime the complex.
Thereafter, the sample is taken out of the treatment chamber 1. The
sample is compared with that before the cleaning in weight to
obtain the amount of etched copper.
[0115] FIG. 6 is a graph showing etched amount when, with a gas
pressure in the treatment chamber 1 fixed at 100 Torr, the
temperature of the susceptor 2 is varied from 150.degree. C. to
300.degree. C. FIG. 7 is a graph showing an etched amount when,
with the temperature of the susceptor 2 fixed at 300.degree. C.,
the gas pressure in the treatment chamber 1 is varied from 10 Torr
to 100 Torr.
[0116] Abscissas of graphs of FIGS. 6 and 7 denote the temperature
of the susceptor 2 and the gas pressure in the treatment chamber 1,
respectively. Ordinates of graphs of FIGS. 6 and 7 each denote
etched amount of copper expressed by the weight change (mg) before
and after the cleaning.
[0117] From FIG. 6, as the temperature rises as 150, 200 and
300.degree. C., the etched amount increases. From FIG. 7, as the
gas pressure rises as 10, 100 Torr, the etched amount
increases.
[0118] The times necessary for complexing in FIGS. 6 and 7 are the
same. Accordingly, the increase of the etched amount means an
increase of the speed of complexing, resultantly an increase of the
speed of etching.
[0119] As mentioned above, due to the increase of the temperature
and gas pressure, the speed of etching (speed of complexing) can be
increased.
[0120] (Embodiment 3)
[0121] In the present embodiment 3, in the course of complexing,
from the piping 29B water vapor is supplied to measure a change of
weights of the etched copper.
[0122] Samples to measure, gas to use and flow rate of the gas are
the same with Embodiment 2 (sample: wafer W of 2.times.2 mm thereon
copper is deposited, cleaning gas: gas mixture of flow rate 37 sccm
of TFA and flow rate 40 sccm of nitrogen). The temperature of the
susceptor 2 and the gas pressure in the treatment chamber 1 are
300.degree. C. and 100 Torr, respectively, that showed the maximum
etched amount in Embodiment 2. The time for the step of complexing
is 3 min.
[0123] FIG. 8 is a graph showing the etched amount of copper when
water vapor is supplied in the treatment chamber 1 in the course of
the complexing in comparison with the case where water vapor is not
employed. The etched amount of copper is expressed, similarly with
embodiment 2, by the weight change (mg) before and after the
cleaning treatment. In the case of water vapor being supplied,
water vapor is supplied by 8.5 sccm (as gas).
[0124] From FIG. 8, by adding water vapor to the cleaning gas by
approximately 19 atomic %, the etched amount of copper is increased
by 37%.
[0125] From the above, it is found that by the addition of the
water vapor, the etching speed (complexing speed) can be
improved.
[0126] (Other Implementation Mode)
[0127] The present invention is not restricted to the range set
forth in the above implementation modes. In the aforementioned
implementation modes, the explanation is given with CVD equipment
as an example. However, the present invention can be applied in
treatment equipment other than the CVD equipment, for instance in
PVD equipment or the like.
[0128] Furthermore, in the above implementation modes, in the
middle of the piping that supplies the treatment agent to the
treatment chamber, the cleaning agent such as TFA or the like is
supplied. The present invention also can be applied in the
treatment equipment furnished with the piping for directly
supplying the cleaning agent in the treatment chamber 1.
[0129] Furthermore, in the above implementation modes, the
treatment equipment of Si wafers is explained as an example.
However, the present invention also can be applied in the treatment
equipment for treating glass substrates for liquid crystal display
(LCD).
* * * * *