U.S. patent application number 12/292995 was filed with the patent office on 2009-06-11 for method for manufacturing semiconductor device and substrate processing apparatus.
This patent application is currently assigned to HITACHI KOKUSAI ELECTRIC INC.. Invention is credited to Kenji Kameda, Yuji Urano, Jie Wang.
Application Number | 20090149032 12/292995 |
Document ID | / |
Family ID | 40722116 |
Filed Date | 2009-06-11 |
United States Patent
Application |
20090149032 |
Kind Code |
A1 |
Kameda; Kenji ; et
al. |
June 11, 2009 |
Method for manufacturing semiconductor device and substrate
processing apparatus
Abstract
The present invention suppresses metallic contamination in a
processing chamber and a breakage of a quartz member, while
suppressing decrease in film formation rate in a thin film
formation process immediately after dry cleaning of the inside of
the processing chamber, and enhances the operation rate of a
apparatus. The method according to the invention includes the steps
of: removing the thin film on the inside of the processing chamber
by supplying a fluorine gas solely or a fluorine gas diluted by an
inert gas solely, as the cleaning gas, to the inside of the
processing chamber heated to a first temperature; and removing an
adhered material remaining on the inside of the processing chamber
after removing the thin film by supplying a fluorine gas solely or
a fluorine gas diluted by an inert gas solely, as the cleaning gas,
to the inside of the processing chamber heated to a second
temperature.
Inventors: |
Kameda; Kenji; (Toyama-shi,
JP) ; Wang; Jie; (Toyama-shi, JP) ; Urano;
Yuji; (Toyama-shi, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 320850
ALEXANDRIA
VA
22320-4850
US
|
Assignee: |
HITACHI KOKUSAI ELECTRIC
INC.
Tokyo
JP
|
Family ID: |
40722116 |
Appl. No.: |
12/292995 |
Filed: |
December 2, 2008 |
Current U.S.
Class: |
438/778 ;
118/708; 257/E21.002; 257/E21.302; 438/791 |
Current CPC
Class: |
C23C 16/4405
20130101 |
Class at
Publication: |
438/778 ;
118/708; 438/791; 257/E21.302; 257/E21.002 |
International
Class: |
H01L 21/321 20060101
H01L021/321; B05C 11/00 20060101 B05C011/00; H01L 21/02 20060101
H01L021/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 5, 2007 |
JP |
2007-314775 |
Feb 27, 2008 |
JP |
2008-046073 |
Oct 8, 2008 |
JP |
2008-261326 |
Claims
1. A method for manufacturing a semiconductor device comprising the
steps of: loading a substrate into a processing chamber; performing
a processing of forming a thin film on the substrate by supplying a
processing gas to an inside of the processing chamber heated to a
processing temperature; unloading the processed substrate out of
the processing chamber; and cleaning the inside of the processing
chamber by supplying a cleaning gas to the inside of the processing
chamber, in a state where the substrate is not present in the
processing chamber, wherein the step of cleaning the inside of the
processing chamber comprises the steps of: removing the thin film
deposited on the inside of the processing chamber by supplying a
fluorine gas solely or a fluorine gas diluted by an inert gas
solely, as the cleaning gas, to the inside of the processing
chamber heated to a first temperature; and removing an adhered
material remaining on the inside of the processing chamber after
removing the thin film by supplying a fluorine gas solely or a
fluorine gas diluted by an inert gas solely, as the cleaning gas,
to the inside of the processing chamber heated to a second
temperature.
2. The method for manufacturing a semiconductor device according to
claim 1, wherein the first temperature is set to not less than
350.degree. C. and not more than 450.degree. C., and the second
temperature is set to not less than 400.degree. C. and not more
than 500.degree. C.
3. The method for manufacturing a semiconductor device according to
claim 1, wherein both the first and second temperatures are set to
not less than 400.degree. C. and not more than 450.degree. C.
4. The method for manufacturing a semiconductor device according to
claim 1, wherein the second temperature is set to equal to or
higher than the first temperature.
5. The method for manufacturing a semiconductor device according to
claim 2, wherein a pressure in the processing chamber is set to not
less than 6650 Pa and not more than 26600 Pa in the step of
cleaning the inside of the processing chamber.
6. The method for manufacturing a semiconductor device according to
claim 1, further comprising the step of: in the state where the
substrate is not present in the processing chamber, purging the
inside of the processing chamber with gas while applying a thermal
impact onto the thin film deposited on the inside of the processing
chamber by decreasing a temperature in the processing chamber to a
temperature lower than the processing temperature, so as to
forcibly generate a crack in the thin film and forcibly peel the
adhered material adhered on the inside of the processing chamber
with a weak adhesive force.
7. A method for manufacturing a semiconductor device comprising the
steps of: loading a substrate into a processing chamber composed of
a member including a quartz member and a metal member; performing a
processing of forming a silicon nitride film on the substrate by
supplying a processing gas to an inside of the processing chamber;
unloading the processed substrate out of the processing chamber;
and cleaning the inside of the processing chamber by supplying a
cleaning gas to the inside of the processing chamber, in a state
where the substrate is not present in the processing chamber,
wherein the step of cleaning the inside of the processing chamber
comprises the steps of: removing the silicon nitride film deposited
on the inside of the processing chamber by supplying a fluorine gas
solely or a fluorine gas diluted by an inert gas solely, as the
cleaning gas, to the inside of the processing chamber in which a
temperature is set to not less than 350.degree. C. and not more
than 450.degree. C. and a pressure is set to not less than 6650 Pa
and not more than 26600 Pa; and removing an adhered material
including a quarts powder remaining on the inside of the processing
chamber after removing the silicon nitride film by supplying a
fluorine gas solely or a fluorine gas diluted by an inert gas
solely, as the cleaning gas, to the inside of the processing
chamber in which a temperature is set to not less than 400.degree.
C. and not more than 500.degree. C. and a pressure is set to not
less than 6650 Pa and not more than 26600 Pa.
8. A substrate processing apparatus comprising: a processing
chamber for performing a processing of forming a thin film on a
substrate; a processing gas supply system for supplying a
processing gas to an inside of the processing chamber; a cleaning
gas supply system for supplying a cleaning gas to the inside of the
processing chamber; a heater for heating the inside of the
processing chamber; and a controller for controlling the heater,
the processing gas supply system, and the cleaning gas supply
system, so as to, when performing the processing on the substrate
in the processing chamber, perform the processing of forming a thin
film on the substrate by supplying a processing gas to the inside
of the processing chamber while heating the inside of the
processing chamber to a processing temperature; and so as to, when
cleaning the inside of the processing chamber, in a state where the
substrate is not present in the processing chamber, remove the thin
film deposited on the inside of the processing chamber by supplying
a fluorine gas solely or a fluorine gas diluted by an inert gas
solely, as the cleaning gas, to the inside of the processing
chamber while heating the inside of the processing chamber to a
first temperature, and subsequently remove an adhered material
remaining on the inside of the processing chamber after removing
the thin film by supplying a fluorine gas solely or a fluorine gas
diluted by an inert gas solely, as the cleaning gas, to the inside
of the processing chamber while heating the inside of the
processing chamber to a second temperature.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method for manufacturing
a semiconductor device including a process of processing a
substrate, and relates to a substrate processing apparatus.
[0003] 2. Description of the Related Art
[0004] As one of processes in a manufacturing process of a
semiconductor device, there is a thin film formation process of
forming a CVD thin film such as a silicon nitride film
(Si.sub.3N.sub.4 film) or the like, on a substrate such as a
semiconductor wafer or the like, with use of a thermal chemical
vapor deposition method (thermal CVD method). The thin film
formation process using the thermal CVD method is performed by
supplying a processing gas to the inside of a processing chamber
into which the substrate has been loaded. The purpose of the thin
film formation process is to form a thin film on a surface of the
substrate. However, practically, a deposited material containing
thin films can sometimes be adhered to a portion other than the
surface of the substrate, for example, an inner wall of the
processing chamber, or the like. Such a deposited material is
cumulatively adhered every time when the thin film formation
process is performed. When the thickness of the deposited material
reaches or exceeds a certain thickness, the deposited material
peels from the inner wall, or the like, of the processing chamber,
which may cause generation of foreign substances (particles) in the
processing chamber. Accordingly, it is necessary to perform
cleaning of the inside of the processing chamber and members in the
processing chamber by removing the deposited material every time
the thickness of the deposited material reaches a certain
thickness.
[0005] Conventionally, a wet cleaning method of detaching a
reaction tube constituting the processing chamber from the
substrate processing apparatus, and then removing a deposited
material adhered to the inner wall of the reaction tube is removed
in a washing tank containing HF (hydrogen fluoride) aqueous
solution, as a mainstream method of removing a deposited material.
However, recently, use of a dry cleaning method which does not
require detaching the reaction tube has been increasing. For
example, a dry cleaning method of supplying a gas mixture in which
HF (hydrogen fluoride) gas or H.sub.2 (hydrogen) gas has been added
to F.sub.2 (fluorine) gas is supplied to the inside of the
processing chamber and other methods are known (for example, see
Japanese Patent Application Laid-open No. 2005-277302, Japanese
Patent Application Laid-open No. 2005-317920, and Japanese Patent
Application Laid-open No. 2007-113778).
[0006] However, when the above-described dry cleaning is performed,
the film formation speed (film formation rate) is sometimes
decreased in the thin film formation process which is immediately
after the dry cleaning. In order to prevent decrease in the film
formation rate, a method is also conceivable which makes the inner
wall, or the like, of the processing chamber flat by supplying the
inside of the processing chamber with a gas mixture in which HF gas
or H.sub.2 gas has been added to F.sub.2 gas immediately after the
dry cleaning. However, in this method, the HF gas which has been
added, or HF gas generated by the reaction of F.sub.2 gas and
H.sub.2 gas sometimes causes metallic contamination due to
corrosion of a metal member in the processing chamber or breakage
of a quartz member in the processing chamber due to erosion.
SUMMARY OF THE INVENTION
[0007] Therefore, it is an object of the present invention to
provide a method for manufacturing a semiconductor device, and a
substrate processing apparatus, enabling suppressing metallic
contamination in a processing chamber and breakage of a quartz
member, while suppressing decrease in a film formation rate in a
thin film formation process which is immediately after the dry
cleaning of the inside of the processing chamber.
[0008] According to one aspect of the present invention, a method
for manufacturing a semiconductor device is provided. The method
includes the steps of: loading a substrate into a processing
chamber; performing a processing of forming a thin film on the
substrate by supplying a processing gas to an inside of the
processing chamber heated to a processing temperature; unloading
the processed substrate out of the processing chamber; and cleaning
the inside of the processing chamber by supplying a cleaning gas to
the inside of the processing chamber, in a state where the
substrate is not present in the processing chamber. The step of
cleaning the inside of the processing chamber includes the steps
of: removing the thin film deposited on the inside of the
processing chamber by supplying a fluorine gas solely or a fluorine
gas diluted by an inert gas solely, as the cleaning gas, to the
inside of the processing chamber heated to a first temperature; and
removing an adhered material remaining on the inside of the
processing chamber after removing the thin film by supplying a
fluorine gas solely or a fluorine gas diluted by the inert gas
solely, as the cleaning gas, to the inside of the processing
chamber heated to a second temperature.
[0009] According to another aspect of the present invention, a
method for manufacturing a semiconductor device is provided. The
method includes the steps of: loading a substrate into a processing
chamber composed of a member including a quartz member and a metal
member; performing a processing of forming a silicon nitride film
on the substrate by supplying a processing gas to an inside of the
processing chamber; unloading the processed substrate out of the
processing chamber; and cleaning the inside of the processing
chamber by supplying a cleaning gas to the inside of the processing
chamber, in a state where the substrate is not present in the
processing chamber. The step of cleaning the inside of the
processing chamber includes the steps of: removing the silicon
nitride film deposited on the inside of the processing chamber by
supplying a fluorine gas solely or a fluorine gas diluted by an
inert gas solely, as the cleaning gas, to the inside of the
processing chamber in which a temperature is set to not less than
350.degree. C. and not more than 450.degree. C. and a pressure is
set to not less than 6650 Pa and not more than 26600 Pa; and
removing an adhered material including a quarts powder remaining on
the inside of the processing chamber after removing the silicon
nitride film by supplying a fluorine gas solely or a fluorine gas
diluted by the inert gas solely, as the cleaning gas, to the inside
of the processing chamber in which a temperature is set to not less
than 400.degree. C. and not more than 500.degree. C. and a pressure
is set to not less than 6650 Pa and not more than 26600 Pa.
[0010] According to a still another aspect of the present
invention, a substrate processing apparatus is provided. The
substrate processing apparatus includes: a processing chamber for
performing a processing of forming a thin film on a substrate; a
processing gas supply system for supplying a processing gas to an
inside of the processing chamber; a cleaning gas supply system for
supplying a cleaning gas to the inside of the processing chamber; a
heater for heating the inside of the processing chamber; and a
controller for controlling the heater, the processing gas supply
system, and the cleaning gas supply system, so as to, when
performing the processing on the substrate in the processing
chamber, perform the processing of forming a thin film on the
substrate by supplying a processing gas to the inside of the
processing chamber while heating the inside of the processing
chamber to a processing temperature; and so as to, when cleaning
the inside of the processing chamber, remove the thin film
deposited on the inside of the processing chamber by supplying a
fluorine gas solely or a fluorine gas diluted by an inert gas
solely, as the cleaning gas, to the inside of the processing
chamber while heating the inside of the processing chamber to a
first temperature, and subsequently remove an adhered material
remaining on the inside of the processing chamber after removing
the thin film by supplying a fluorine gas solely or a fluorine gas
diluted by an inert gas solely, as the cleaning gas, to the inside
of the processing chamber while heating the inside of the
processing chamber to a second temperature, in a state where the
substrate is not present in the processing chamber.
[0011] The method for manufacturing a semiconductor device and the
substrate processing apparatus according to the present invention
enable suppressing metallic contamination in the processing chamber
and erosion of the quartz members while suppressing decrease in
film formation rate in the thin film formation process immediately
after dry cleaning of the inside of the processing chamber, and
enhancing the operation rate of the substrate processing
apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a schematic view of a general CVD thin film
formation apparatus for a semiconductor;
[0013] FIG. 2 is a graph chart showing a sequence and cleaning
conditions of a cleaning step according to Example 1 of the present
invention;
[0014] FIG. 3 is a graph chart showing a sequence and cleaning
conditions of a cleaning step of according to Example 2 of the
present invention;
[0015] FIG. 4 is a graph chart showing a validation data on an
amount of foreign substances generated according to the Example 2
of the present invention;
[0016] FIG. 5 is a graph chart showing a validation data on
reproducibility of a film formation rate according to the Example 2
of the present invention;
[0017] FIG. 6A is a graph chart showing temperature dependence of
an etching rate of silicon nitride film, an etching rate of quartz,
and a selection ratio, respectively, and FIG. 6B is a table chart
shows a data on which FIG. 6A is based.
[0018] FIG. 7 is a schematic view of a processing furnace of a
substrate processing apparatus which is preferably used in one
embodiment of the present invention;
[0019] FIG. 8 is a graph chart showing transition of particles
generated after a dry cleaning process;
[0020] FIG. 9 is a graph chart showing stability of particles after
a dry cleaning process according to Example 3 of the present
invention;
[0021] FIG. 10 is a schematic view of a processing furnace of a
substrate processing apparatus including a forced-cooling mechanism
which is preferably used in the Example 3 of the present invention;
and
[0022] FIG. 11A is a schematic view illustrating a change of a
quartz surface in the case where a treatment process is not
performed after a thin film etching process, and FIG. 11B is a
schematic view illustrating a change of a quartz surface in the
case where a treatment process is performed after a thin film
etching process.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] As described above, a CVD thin film is formed by supplying a
processing gas to the inside of the processing chamber into which
the substrate has been loaded. Hereinafter, a structure of a
general thin film forming apparatus and a thin film formation
process will be briefly described respectively.
[0024] The structure of a general CVD thin film formation apparatus
for a semiconductor will be described with reference to FIG. 1.
This thin film forming apparatus includes: a reaction tube 103
which includes therein a film formation chamber (processing
chamber) 101 for processing substrates 100; a boat 102 for holding
in multiple stages the substrates 100 in a horizontal posture in
the film formation chamber 101, a heat source 104 located around
the reaction tube 103; a processing gas supply line 105 for
supplying the inside of the film formation chamber 101 with a
processing gas for forming a CVD thin film; a cleaning gas supply
line 107 for supplying a cleaning gas for removing a deposited
material by etching it to the inside of the film formation chamber
101; an exhaust line 108 in which a pressure adjustment valve 106
for adjusting a pressure in the film formation chamber 101 and a
vacuum pump 109 downstream thereof are provided. The reaction tube
103 and the boat 102 are made of quartz (SiO.sub.2).
[0025] Subsequently, the thin film formation process performed by
this thin film forming apparatus will be described. First, the boat
102 holding a plurality of the substrates 100 is loaded to the
inside of the film formation chamber 101. Next, a surface of the
substrate 100 is heated to a predetermined temperature by the heat
source 104. Subsequently, while the inside of the film formation
chamber 101 is evacuated by the exhaust line 108, processing gas is
supplied to the inside of the film formation chamber 101 by the
processing gas supply line 105, and a thin film is formed on the
substrate 100 according to the CVD (Chemical Vapor Deposition)
reaction. At this time, the pressure in the film formation chamber
101 is adjusted so as to be kept at a constant pressure by the
pressure adjustment valve 106 provided in the exhaust line 108.
When a thin film with a predetermined film thickness is formed on
the substrate 100, supply of processing gas from the processing gas
supply line 105 is stopped. Next, the temperature of the substrate
100 after the thin film is formed is decreased to a predetermined
temperature, and subsequently the boat 102 is unloaded to the
outside of the film formation chamber 101.
[0026] The intended objective of the above-described thin film
formation process is to form a thin film on the substrate 100.
However, practically, when the thin film is formed on the substrate
100, a deposited material containing the thin film can sometimes
also be adhered to an inner wall of the film formation chamber 101
and a member such as the boat 102, or the like. Such deposited
material is cumulatively adhered every time the above-described
thin film formation process is performed, and when the thickness
thereof reaches or exceeds a certain thickness the deposited
material peels off or drops, which can lead to generation of
foreign substances on the substrate 100. Therefore, it is necessary
to remove the deposited material every time the thickness of the
deposited material reaches a certain thickness.
[0027] As a method of removing the deposited material, there are
known the wet cleaning method of detaching the reaction tube 103
and immersing it in a washing solution containing HF aqueous
solution, thereby to remove a deposited material by means of wet
etching, and the dry cleaning method of supplying an etching gas
(cleaning gas) to the inside of the film formation chamber 101,
thereby to remove a deposited material by means of dry etching.
Recently, use of the dry cleaning methods which do not require
detaching of the reaction tube 103 has started. Hereinafter, the
dry cleaning method will be briefly described.
[0028] First, the empty boat 102 with the deposited material
adhered to the surface thereof is loaded into the film formation
chamber 101 with the deposited material adhered to the inside
thereof. Next, the inside of the film formation chamber 101 is
heated to a predetermined temperature by the heat source 104.
Subsequently, while the inside of the film formation chamber 101 is
evacuated by the exhaust line 108, a cleaning gas is supplied to
the inside of the film formation chamber 101 by the cleaning gas
supply line 107, whereby the deposited material adhered to the
inside of the film formation chamber 101 or the surface of the boat
102 is removed by the etching reaction between active species
generated by degradation of the cleaning gas and the deposited
material. At this time, the pressure in the film formation chamber
101 is adjusted so as to be kept at a constant pressure by the
pressure adjustment valve 106 provided in the exhaust line 108.
After the deposited material in the film formation chamber 101 is
removed, supply of the cleaning gas from the cleaning gas supply
line 107 is stopped. Next, the seasoning process in the film
formation chamber 101 is performed. Specifically, processing gas is
supplied to the inside of the film formation chamber 101 into which
the substrate 100 has not been loaded, and a thin film is formed
(pre-coated) on the inner wall of the film formation chamber 101,
whereby the state of the film formation chamber 101 is restored to
a state which enables transition to the thin film formation
process.
[0029] Examples of the cleaning gases include, for example,
NF.sub.3 (nitrogen trifluoride) gas, ClF.sub.3 (chlorine
trifluoride) gas, F.sub.2 (fluorine) gas, or a gas mixture in which
HF (hydrogen fluoride) gas or H.sub.2 (hydrogen) gas has been added
to either of these gases. Provided that, since it is difficult to
thermally decompose NF.sub.3 gas at a low temperature not more than
500.degree. C., it is necessary to set the temperature in the film
formation chamber 101 to a high temperature not less than
600.degree. C. when NF.sub.3 gas is used as an etching gas.
Accordingly, dry cleaning technologies using F.sub.2 gas, CF.sub.3
gas, or HF gas are being developed. In particular, F.sub.2 gas is
strongly reactive and the etching reaction thereof easily develops.
Therefore, addition of HF gas to F.sub.2 gas can further promote
the etching reaction. Japanese Patent Application Laid-open No.
2005-277302 discloses the dry cleaning method of changing the
temperature in the film formation chamber 101 in stages with use of
a gas mixture of F.sub.2 gas and HF gas, or the dry cleaning method
of maintaining the temperature in the film formation chamber 101
constantly or changing it in stages, thereby to switch the cleaning
gas from the gas mixture in which HF gas has been added to F.sub.2
gas to F.sub.2 gas. These methods enable preventing a remaining
adhered material from being left in the film formation chamber 101
and suppressing generation of foreign substances.
[0030] However, when a dry cleaning using the gas mixture of
F.sub.2 gas and HF gas is performed, the film formation rate can be
sometimes decreased in the thin film formation process which is
immediately after the dry cleaning. The decrease in the film
formation rate is presumed to be caused by an increased effective
surface area of the surfaces of quartz members (the reaction tube
103 and the boat 102), due to minute quartz powders remaining on
and adhered to the surfaces of the quartz members in the film
formation chamber 101 after the cleaning, and due to cracks on the
surfaces of the quartz members because of cumulative film
formations.
[0031] As a method to prevent the decrease in the film formation
rate, Japanese Patent Application Laid-open No. 2005-317920
discloses the method of supplying the gas mixture in which HF gas
has been added to F.sub.2 gas, to the inside of the film formation
chamber 101, immediately after the dry cleaning, thereby to make
the inner wall of the film formation chamber 101 flat (in other
words, to remove quartz cracks generated in the quartz members).
Note that, Japanese Patent Application Laid-open No. 2005-317920
clearly states that use of F.sub.2 gas solely or HF gas solely can
remove little quartz cracks, whereby decrease in the film formation
rate is not avoidable.
[0032] As another method to prevent the decrease in the film
formation rate, Japanese Patent Application Laid-open No.
2007-113778 discloses the method of cleaning the inside of the film
formation chamber 101 by supplying, the cleaning gas in which
H.sub.2 gas has been added to F.sub.2 gas, to the inside of the
film formation chamber 101, and subsequently, supplying a
flattening gas in which H.sub.2 gas has been added to F.sub.2 gas,
to the inside of the film formation chamber 101, so as to make the
inner wall of the film formation chamber 101 flat (in other words,
to remove quartz cracks generated in the quartz members). Note
that, Japanese Patent Application Laid-open No. 2007-113778 clearly
states that it is necessary to add H.sub.2 gas to the cleaning gas
and that the flattening gas should preferably contain a small
amount of H.sub.2 gas.
[0033] However, when the gas mixture in which HF gas has been added
to F.sub.2 gas is supplied to the inside of the film formation
chamber 101 immediately after the dry cleaning (in other words,
when HF gas is directly supplied to the inside of the film
formation chamber 101), metallic contamination can sometimes occur
because metal members in the film formation chamber 101 are
corroded by the HF gas which has been supplied, or the quartz
member can break because of a significant erosion of quartz caused
by multilayered HF adsorbed on the quartz member at a
low-temperature portion of the film formation chamber 101.
Furthermore, when the gas mixture in which H.sub.2 gas has been
added to F.sub.2 gas is supplied to the inside of the film
formation chamber 101, HF gas can be generated in the film
formation chamber 101 by the reaction between F.sub.2 gas and
H.sub.2 gas, which can lead not only to the above-described
metallic contamination and breakage of the quartz members, but also
to a risk of explosion in the film formation chamber 101 under some
conditions.
[0034] Therefore, the inventors and the like have made earnest
researches on the method which suppresses metallic contamination
and breakage of the quartz members in the film formation chamber
101, while suppressing decrease in the film formation rate in the
thin film formation process which is immediately after the dry
cleaning in the film formation chamber 101. As a result, the
inventors have acquired the knowledge that the above-described
problem can be solved by supplying F.sub.2 gas solely or F.sub.2
gas diluted by an inert gas solely to the inside of the film
formation chamber 101, while optimizing the temperature conditions.
Specifically, the inventors have acquired the knowledge that the
above-described problem can be solved by the step of removing the
thin film deposited on the inside of the processing chamber by
supplying F.sub.2 gas solely or F.sub.2 gas diluted by an inert gas
solely, as the cleaning gas, to the inside of the processing
chamber heated to a first temperature; and the step of removing an
adhered material remaining on the inside of the processing chamber
after removing the thin film by supplying F.sub.2 gas solely or
F.sub.2 gas diluted by an inert gas solely, as the cleaning gas, to
the inside of the processing chamber heated to a second
temperature. The present invention has been made based on the
knowledge acquired by the inventors.
[0035] Hereinafter, one embodiment of the present invention will be
described.
[0036] 1. The Structure of the Substrate Processing Apparatus
[0037] First, the structure of a substrate processing apparatus
according to the present embodiment will be described with
reference to the drawings. FIG. 7 is a schematic structural view,
shown as a longitudinal sectional view, of a processing furnace 202
of a substrate processing apparatus which is preferably used in the
present embodiment.
[0038] As shown in FIG. 7, the processing furnace 202 includes a
heater 206 which serves as the heating mechanism. The heater 206,
having a cylindrical shape, is installed vertically by being
supported by a heater base 251 which serves as the holding
plate.
[0039] Inside the heater 296, a process tube 203 which serves as
the reaction tube is arranged concentrically with the heater 206.
The process tube 203 includes an inner tube 204 which serves as the
inner reaction tube, and an outer tube 205 which serves as the
outer reaction tube provided outside thereof. The inner tube 204 is
made of, for example, a heat-resistant material such as quartz
(SiO.sub.2), silicon carbide (SiC) or the like, and formed into a
cylindrical shape with upper and lower ends thereof being opened. A
processing chamber 201 for performing a processing of forming a
thin film on wafers 200 which serve as the substrates is formed in
a cylindrical hollow portion of the inner tube 204. The processing
chamber 201 is configured to accommodate the wafers 200 in a state
where the wafers 200 in a horizontal posture are aligned in
multiple stages in the vertical direction by means of a boat 217 to
be described later. The outer tube 205 is made of, for example, a
heat-resistant material such as quartz, silicon carbide or the
like, has been formed into a cylindrical shape, with an inner
diameter thereof being larger than an outer diameter of the inner
tube 204, and with an upper end thereof being closed and a lower
end thereof being opened, and is provided concentrically with the
inner tube 204.
[0040] A manifold 209 is arranged concentrically with the outer
tube 205 below the outer tube 205. The manifold 209 is made of, for
example, stainless steel or the like, and has been formed into a
cylindrical shape with upper and lower ends thereof being opened.
The manifold 209, engaged with the inner tube 204 and the outer
tube 205, is provided so as to support them. Note that, an O ring
220a which serves as the sealing member is provided between the
manifold 209 and the outer tube 205. The process tube 203 is
installed vertically by the manifold 209 being supported by the
heater base 251. A reaction container is formed by the process tube
203 and the manifold 209.
[0041] The manifold 209 is connected to nozzles 230a, 230b which
serve as the gas introduction portions; such that they are
communicated with the inside of the processing chamber 201.
Processing gas supply tubes 232a, 232b which supply a processing
gas for forming a thin film to the inside of the processing chamber
201 are connected to the nozzles 230a, 230b, respectively. An
SiH.sub.2Cl.sub.2 (DCS) gas supply source 271 which serves as the
first processing gas supply source is connected, via an MFC (mass
flow controller) 241a which serves as the gas flow rate controller,
to the processing gas supply tube 232a, at the upstream side
thereof opposite to the side connected to the nozzle 230a. Valves
262a, 261a are respectively provided in the processing gas supply
tube 232a at the upstream and downstream of the MFC 241a. An
NH.sub.3 gas supply source 272 which serves as the second
processing gas supply source is connected, via an MFC (mass flow
controller) 241b which serves as the gas flow rate controller, to
the processing gas supply tube 232b at the upstream side thereof
opposite to the side connected to the nozzle 230b. Valves 262b,
261b are respectively provided in the processing gas supply tube
232b at the upstream and downstream of the MFC 241b. A processing
gas supply system is constituted mainly by the processing gas
supply tubes 232a, 232b, the MFCs 241a, 241b, the valves 262a,
261a, 262b, and 261b, the SiH.sub.2Cl.sub.2 gas supply source 271,
and the NH.sub.3 gas supply source 272.
[0042] Inert gas supply tubes 232c, 232d are connected to the
processing gas supply tubes 232a, 232b at the downstream of the
valves 261a, 261b, respectively. An N.sub.2 gas supply source 273
which serves as the inert gas supply source is connected, via an
MFC (mass flow controller) 241c which serves as the gas flow rate
controller, to the inert gas supply tube 232c at the upstream side
thereof opposite to the side connected to the processing gas supply
tube 232a. Valves 262c, 261c are respectively provided in the inert
gas supply tube 232c at the upstream and downstream of the MFC
241c, respectively. The N.sub.2 gas supply source 273 which serves
as the second processing gas supply source is connected, via an MFC
(mass flow controller) 241d which serves as the gas flow rate
controller, to the inert gas supply tube 232d at the upstream side
thereof opposite to the connection side with the processing gas
supply tube 232b. Exactly speaking, the inert gas supply tube 232d
at the upstream side thereof is connected to the inert gas supply
tube 232c at the upstream of the valves 262c, and the inert gas
supply tube 232d is provided so as to branch from the inert gas
supply tube 232c at the upstream of the valve 262c. An inert gas
supply system is constituted mainly by the inert gas supply tubes
232c, 232d, the MFCs 241c, 241d, the valves 262c, 261c, 262d, and
261d, and the N.sub.2 gas supply source 273. Note that, the inert
gas supply system also has a function of diluting a processing gas
or a cleaning gas, and the inert gas supply system also constitutes
a part of the processing gas supply system and a part of the
cleaning gas supply system. In addition, the inert gas supply
system also functions as a purge gas supply system.
[0043] Cleaning gas supply tubes 232e, 232f which supply a cleaning
gas for cleaning the inside of the processing chamber 201 to the
inside of the processing chamber 201 are respectively connected to
the processing gas supply tubes 232a, 232b, at the downstream of
the valves 261a, 261b, and at further downstream of connecting
portions with the inert gas supply tubes 232c, 232d. An F.sub.2 gas
supply source 274 which serves as the cleaning gas supply source is
connected, via an MFC (mass flow controller) 241e which serves as
the gas flow rate controller, to the cleaning gas supply tube 232e
at the upstream side thereof opposite to the side connected to the
processing gas supply tube 232a. Valves 262e, 261e are respectively
provided in the cleaning gas supply tube 232e at the upstream and
downstream of the MFC 241e. The F.sub.2 gas supply source 274 which
serves as the cleaning gas supply source is connected, via an MFC
(mass flow controller) 241f which serves as the gas flow rate
controller, to the cleaning gas supply tube 232f at the upstream
side thereof opposite to the side connected to the processing gas
supply tube 232b. Exactly speaking, the cleaning gas supply tube
232f at the upstream side thereof is connected to the cleaning gas
supply tube 232e at the upstream of the valve 262e, and the
cleaning gas supply tube 232f is provided so as to branch from the
cleaning gas supply tube 232e at the upstream of the valve 262e.
Valves 262f, 261f are respectively provided in the cleaning gas
supply tube 232f at the upstream and downstream of the MFC241f. A
cleaning gas supply system is constituted mainly by the cleaning
gas supply tubes 232e, 232f the MFCs 241e, 241f, the valves 262e,
261e, 262f, and 261f, and the F.sub.2 gas supply source 274.
[0044] A gas supplying and flow rate controlling portion 235 is
electrically connected to the MFCs 241a, 241b, 241c, 241d, 241e,
and 241f, and the valves 261a, 261b, 261c, 261d, 261e, 261f, 262a,
262b, 262c, 262d, 262e, and 262f. The gas supplying and flow rate
controlling portion 235 is configured to control the MFCs 241a,
241b, 241c, 241d, 241e, and 241f, and the valves 261a, 261b, 261c,
261d, 261e, 261f, 262a, 262b, 262c, 262d, 262e, and 262f at desired
timings, such that the type of the gas to be supplied to the inside
of the processing chamber 201 in individual steps, which will be
described later, is a desired gas type, such that the flow rate of
the gas to be supplied is a desired flow rate, and such that the
concentration of the gas to be supplied is a desired
concentration.
[0045] The manifold 209 is provided with an exhaust pipe 231 which
exhausts atmosphere in the processing chamber 201. The exhaust pipe
231, which is located at a lower end portion of a cylindrical space
250 formed by a clearance between the inner tube 204 and the outer
tube 205, is communicated with the cylindrical space 250. A vacuum
exhaust unit 246, such as a vacuum pump, is connected, via a
pressure sensor 245 which serves as the pressure detector, and a
pressure adjustment unit 242, such as a variable conductance valve,
for example, APC (Auto Pressure Controller) valve or the like, to
the exhaust pipe 231 at the downstream thereof opposite to the side
connected to the manifold 209. The vacuum exhaust unit 246 is
configured to be capable of vacuum evacuation such that the
pressure in the processing chamber 201 becomes a predetermined
pressure (degree of vacuum). A pressure controller 236 is
electrically connected to the pressure adjustment unit 242 and the
pressure sensor 245. The pressure controller 236 is configured to
control the pressure adjustment unit 242 at desired timings on the
basis of the pressure detected by the pressure sensor 245, such
that the pressure in the processing chamber 201 becomes a desired
pressure. An exhaust system is constituted mainly by the exhaust
pipe 231, the pressure adjustment unit 242, and the vacuum exhaust
unit 246.
[0046] A seal cap 219 which serves as the first furnace opening
cover body and enables closing a lower end opening of the manifold
209 in an air tight manner below the manifold 209. The seal cap 219
is configured to abut with the lower end of the manifold 209 upward
in the vertical direction. The seal cap 219, which is made of, for
example, a metal such as stainless steel, is formed into a disk
shape. An O ring 220b, serving as the sealing member and abutting
with the lower end of the manifold 209, is provided on a top
surface of the seal cap 219. A rotation mechanism 254 for rotating
the boat is mounted to the seal cap 219 on the opposite side of the
side of the processing chamber 201. A rotational axis 255 of the
rotation mechanism 254, passing through the seal cap 219, is
connected to the boat 217 which will be described later, and
configured so as to rotate the wafers 200 by rotating the boat 217.
The seal cap 219 is configured to be raised and lowered in the
vertical direction by a boat elevator 115 which serves as the
raising and lowering mechanism and which is installed vertically to
the outside of the process tube 203. This configuration enables the
boat 217 to be loaded to and unloaded from the processing chamber
201. A drive controller 237 is electrically connected to the
rotation mechanism 254 and the boat elevator 115. The drive
controller 237 is configured to control the rotation mechanism 254
and the boat elevator 115 at desired timings such that they perform
desired operations. In addition, a furnace opening shutter 219a,
which serves as the second furnace opening cover body and which
enables closing the lower end opening of the manifold 209 in an air
tight manner, is provided below the manifold 209. The shutter 219a
is configured to be raised/lowered and rotated so as to abut with
the lower end of the manifold 209, after the boat 217 is unloaded
from the inside of the processing chamber 201, and to close the
inside of the processing chamber 201 in an air tight manner after
the boat 217 is unloaded. An O ring 220c, which serves as the
sealing member and which abuts with the lower end of the manifold
209, is provided on a top surface of the shutter 219a.
[0047] The boat 217, which serves as the substrate holder, is made
of, for example, a heat-resistant material, such as, quartz,
silicon carbide or the like. The boat 217 is configured to hold, in
multiple stages, a plurality of the wafers 200 which are aligned in
a horizontal posture with the centers thereof being matched. Note
that, a plurality of disk-shaped heat insulation boards 216, which
serve as the heat insulating members and are made of, for example,
a heat-resistant material, such as, quartz, silicon carbide or the
like, are arranged in multiple stages in a horizontal posture at a
lower portion of the boat 217. The heat insulation boards 216 are
configured to make it difficult for heat from the heater 206 to be
transmitted to the manifold 209 side.
[0048] A temperature sensor 263 which serves as the temperature
detector is mounted in the process tube 203. A temperature
controller 238 is electrically connected to the heater 206 and the
temperature sensor 263. The temperature controller 238 is
configured to control the conductivity status to the heater 206 at
desired timings on the basis of the temperature information
detected by the temperature sensor 263, such that the processing
chamber 201 has a desired temperature distribution.
[0049] The gas supplying and flow rate controlling portion 235, the
pressure controller 236, the drive controller 237, and the
temperature controller 238, which also constitute an operation
portion and an input/output portion, are electrically connected to
a main controller 239 which controls the entire substrate
processing apparatus. A controller 240 is configured by the gas
supplying and flow rate controlling portion 235, the pressure
controller 236, the drive controller 237, the temperature
controller 238, and the main controller 239.
[0050] (2) The Thin Film Formation Method
[0051] Next, as one of the processes for manufacturing a
semiconductor device, the method of forming a thin film on each
wafer 200 in the processing chamber 201 according to the CVD
method, and the method of cleaning the inside of the processing
chamber 201, both of which use the processing furnace 202 according
to the above-described structure, will be described. Note that, in
the description hereinafter, the operations of the individual
portions that constitute the substrate processing apparatus are
controlled by the controller 240.
[0052] When the boat 217 is charged with a plurality of the wafers
200 (wafer charge), then as shown in FIG. 7, the boat 217 which
holds a plurality of the wafers 200 is raised by the boat elevator
115 and loaded to the inside of the processing chamber 201 (boat
load). In this state, the seal cap 219 seals the lower end of the
manifold 209 via the O ring 220b.
[0053] The processing chamber 201 is vacuum evacuated by the vacuum
exhaust unit 246, such that the pressure therein becomes a desired
pressure (degree of vacuum). At this time, the pressure in the
processing chamber 201 is measured by the pressure sensor 245, and
the pressure adjustment unit 242 is feed-back controlled on the
basis of the measured pressure. In addition, the processing chamber
201 is heated by the heater 206, such that the temperature therein
becomes a desired temperature. At this time, the conductivity
status to the heater 206 is feed-back controlled on the basis of
the temperature information detected by the temperature sensor 263,
such that the processing chamber 201 has a desired temperature
distribution. Subsequently, the boat 217 is rotated by the rotation
mechanism 254, whereby the wafers 200 are rotated.
[0054] Subsequently, SiH.sub.2Cl.sub.2 gas as the first processing
gas and NH.sub.3 gas as the second processing gas are supplied to
the inside of the processing chamber 201 from the SiH.sub.2Cl.sub.2
gas supply source 271 as the first processing gas supply source and
the NH.sub.3 gas supply source 272 as the second processing gas
supply source, respectively, in a state where the temperature and
the pressure in the processing chamber 201 are maintained to a
desired temperature and pressure, respectively. Specifically,
SiH.sub.2Cl.sub.2 gas and NH.sub.3 gas are supplied, from the
SiH.sub.2Cl.sub.2 gas supply source 271 and the NH.sub.3 gas supply
source 272, to the inside of the processing gas supply tubes 232a,
232b, respectively, by the valves 262a, 261a, 262b, and 261b being
opened. SiH.sub.2Cl.sub.2 gas and NH.sub.3 gas are controlled by
the MFCs 241a, 241b, respectively, so as to have desired flow
rates, then pass through the processing gas supply tubes 232a,
232b, respectively, and are introduced via the nozzles 230a, 230b,
respectively, to the inside of the processing chamber 201.
[0055] At this time, N.sub.2 gas may be supplied from the N.sub.2
gas supply source 273 as the inert gas supply source to the inside
of the processing chamber 201 simultaneously, so as to dilute
processing gas (SiH.sub.2Cl.sub.2 gas, NH.sub.3 gas). In this case,
for example, N.sub.2 gas is supplied from N.sub.2 gas supply source
273 to the inside of the inert gas supply tubes 232c, 232d by the
valves 262c, 261c, 262d, and 261d being opened. N.sub.2 gas is
controlled by the MFC241c, 241d so as to have desired flow rates.
Subsequently, N.sub.2 gas passes through the inert gas supply tubes
232c, 232d, via the processing gas supply tubes 232a, 232b, and is
introduced via the nozzles 230a, 230b to the inside of the
processing chamber 201. N.sub.2 gas is mixed with SiH.sub.2Cl.sub.2
gas and NH.sub.3 gas in the processing gas supply tubes 232a, 232b,
respectively. The concentration of processing gas can also be
controlled by controlling the flow rate of N.sub.2 gas
supplied.
[0056] Processing gas introduced to the inside of the processing
chamber 201 goes up inside the processing chamber 201, flows via an
upper end opening of the inner tube 204 to the cylindrical space
250, flows down in the cylindrical space 250, and subsequently is
exhausted from the exhaust pipe 231. When processing gas passes
through the inside of the processing chamber 201, it gets contact
with the surfaces of the wafers 200. At this time, a thin film,
that is, a silicon nitride (Si.sub.3N.sub.4) film is deposited on
the surfaces of the wafers 200 by the thermal CVD reaction.
[0057] When a processing time which has been set in advance passes,
supply of processing gas is stopped. In other words, supplies of
SiH.sub.2Cl.sub.2 gas and NH.sub.3 gas from the SiH.sub.2Cl.sub.2
gas supply source 271 and the NH.sub.3 gas supply source 272,
respectively, to the inside of the processing chamber 201, are
stopped by the valves 262a, 261a, 262b, and 261b being closed.
Subsequently, N.sub.2 gas is exhausted from the exhaust pipe 231
while being supplied from the N.sub.2 gas supply source 273 to the
inside of the processing chamber 201, by the valves 262c, 261c,
262d, and 261d being opened, whereby the inside of the processing
chamber 201 is purged. Next, the atmosphere in the processing
chamber 201 is replaced by N.sub.2 gas, and the pressure in the
processing chamber 201 returns to the normal pressure.
[0058] Subsequently, the seal cap 219 is lowered by the boat
elevator 115, thereby to open the lower end of the manifold 209. At
the same time, the processed wafers 200 are unloaded to the outside
of the process tube 203 via the lower end of the manifold 209 in
the state where the wafers 200 are held by the boat 217 (boat
unload). Subsequently, the processed wafers 200 are taken out from
the boat 217 (wafer discharge).
[0059] Note that, the processing conditions when processing the
wafers 200 in the processing furnace 202 of the present embodiment,
for example, in formation of a silicon nitride film, are as
follows:
[0060] processing temperature: 650 to 800.degree. C.,
[0061] processing pressure: 10 to 500 Pa,
[0062] SiH.sub.2Cl.sub.2 gas supply flow rate: 100 to 500 sccm,
[0063] NH.sub.3 gas supply flow rate: 500 to 5000 sccm.
The wafers 200 are processed by maintaining each of the processing
conditions to a constant value within each specified range.
[0064] (3) The Cleaning Method
[0065] Next, the method of cleaning the inside of the processing
chamber 201 will be described. Note that, in the description
hereinafter, the operations of the individual portions that
constitute the substrate processing apparatus are controlled by the
controller 240.
[0066] When the above-described thin film formation process is
repeated, thin films, such as silicon nitride films or the like,
are accumulated also in the processing chamber 201 such as the
inner wall or the like of the process tube 203. In other words, the
deposited material containing the thin films is adhered to the
inner wall or the like. At the time point when the thickness of the
deposited material (accumulated thin films) adhered to the inner
wall or the like reaches a predetermined thickness before the
deposited material peels off or drops, cleaning of the inside of
the processing chamber 201 is performed.
[0067] The cleaning is performed by sequentially performing: the
step of removing a thin film deposited (accumulated) on the inside
of the processing chamber 201 by supplying F.sub.2 gas solely or
F.sub.2 gas diluted by an inert gas solely, as the cleaning gas, to
the inside of the processing chamber 201 heated to a first
temperature (first step (thin film etching process)); and the step
of removing an adhered material remaining in the processing chamber
201 after removing the thin film, by supplying F.sub.2 gas solely
or F.sub.2 gas diluted by an inert gas solely, as the cleaning gas,
to the inside of the processing chamber 201 heated to a second
temperature (second step (treatment process)). Hereinafter, the
first step (thin film etching process) and the second step
(treatment process) will be described, respectively.
[0068] The First Step (Thin Film Etching Process)
[0069] The empty boat 217, that is, the boat 217 which is not
charged with the wafers 200, is raised by the boat elevator 115 and
loaded to the inside of the processing chamber 201 (boat load). In
this state, the seal cap 219 seals the lower end of the manifold
209 via the O ring 220b.
[0070] The processing chamber 201 is vacuum evacuated by the vacuum
exhaust unit 246, such that the pressure therein becomes a desired
pressure (degree of vacuum), that is, the first pressure. At this
time, the pressure in the processing chamber 201 is measured by the
pressure sensor 245, and the pressure adjustment unit 242 is
feed-back controlled on the basis of the measured pressure. In
addition, the processing chamber 201 is heated by the heater 206,
such that the temperature therein becomes a desired temperature,
that is, the first temperature. At this time, the conductivity
status to the heater 206 is feed-back controlled on the basis of
the temperature information detected by the temperature sensor 263,
such that the processing chamber 201 has a desired temperature
distribution. When the pressure and the temperature in the
processing chamber 201 reach the first pressure and the first
temperature, respectively, control is performed so as to maintain
the pressure and the temperature. Subsequently, the boat 217 is
rotated by the rotation mechanism 254. Meanwhile, the boat 217 need
not be rotated.
[0071] Subsequently, F.sub.2 gas as the cleaning gas is supplied
from the F.sub.2 gas supply source 274 as the cleaning gas supply
source to the inside of the processing chamber 201, in the state
where the temperature and the pressure in the processing chamber
201 are maintained at the first temperature and the first pressure,
respectively. Specifically, F.sub.2 gas is supplied from the
F.sub.2 gas supply source 274 to the inside of the cleaning gas
supply tubes 232e, 232f, by the valves 262e, 261e, 262f, and 261f
being opened. F.sub.2 gas is controlled by the MFCs 241e, 241f so
as to have desired flow rates, and then passes through the cleaning
gas supply tubes 232e, 232f, and by way of the processing gas
supply tubes 232a, 232b, and are introduced via the nozzles 230a,
230b to the inside of the processing chamber 201.
[0072] At this time, N.sub.2 gas may be supplied from the N.sub.2
gas supply source 273 as the inert gas supply source to the inside
of the processing chamber 201 simultaneously, so as to dilute
F.sub.2 gas as the cleaning gas. In this case, for example, N.sub.2
gas is supplied from the N.sub.2 gas supply source 273 to the
inside of the inert gas supply tubes 232c, 232d, respectively, by
the valves 262c, 261c, 262d, and 261d being opened. N.sub.2 gas is
controlled by the MFCs 241c, 241d, respectively so as to have
desired flow rates. Subsequently, N.sub.2 gas passes through the
inert gas supply tubes 232c, 232d, and by way of the processing gas
supply tubes 232a, 232b, and are introduced via the nozzles 230a,
230b to the inside of the processing chamber 201. N.sub.2 gas is
mixed with F.sub.2 gas in the processing gas supply tubes 232a,
232b. The concentration of F.sub.2 gas can also be controlled by
controlling the flow rate of N.sub.2 gas supplied.
[0073] Note that, if F.sub.2 gas or diluted F.sub.2 gas is supplied
via nozzles for a cleaning gas that are different from the nozzles
230a, 230b for supplying processing gases, then F.sub.2 gas or
diluted F.sub.2 gas may enter the nozzles 230a, 230b, which may
give negative influence on the processing gas supply system such as
the processing gas supply tubes 232a, 232b, or the like. On the
contrary, in the present embodiment, the nozzles 230a, 230b for
supplying processing gas are also used as the nozzles for supplying
F.sub.2 gas or diluted F.sub.2 gas. F.sub.2 gas or diluted F.sub.2
gas passes through the processing gas supply tubes 232a, 232b, and
is introduced to the inside of the processing chamber 201 via the
nozzles 230a, 230b for supplying processing gas. Accordingly, there
is little concern on the negative influence.
[0074] F.sub.2 gas or diluted F.sub.2 gas introduced to the inside
of the processing chamber 201 goes up inside the processing chamber
201, flows via the upper end opening of the inner tube 204 to the
cylindrical space 250, flows down in the cylindrical space 250, and
subsequently, is exhausted from the exhaust pipe 231. When F.sub.2
gas or diluted F.sub.2 gas passes through the inside of the
processing chamber 201, it gets contact with a deposited material
containing the thin film such as a silicon nitride film accumulated
on the inner wall of the process tube 203 or the surface of the
boat 217, when the thin film is removed by the thermo-chemical
reaction. Specifically, the thin film is removed by the etching
reaction between active species generated by thermal decomposition
of F.sub.2 gas and the deposited material.
[0075] When an etching time of the thin film which has been set in
advance passes and the first step (thin film etching process) is
completed, then transition to the second step (treatment process)
is made. In the treatment process, the adhered material remaining
in the processing chamber 201 is removed after the thin film
etching process, so as to make the surfaces of the quartz members
in the processing chamber 201 smooth. Specifically, adhered
materials: such as, quartz cracks generated on the surfaces of the
quartz members, such as the process tube 203, the boat 217, or the
like; minute quartz powders (quartz powders) generated due to
quartz cracks or the like and adhered to the surfaces of the quartz
members in the processing chamber 201; a remaining silicon nitride
film, or the like, are removed.
[0076] The Second Step (Treatment Process)
[0077] The processing chamber 201 is vacuum evacuated by the vacuum
exhaust unit 246 such that the pressure therein becomes a desired
pressure, that is, the second pressure, in the state where the boat
217 which is not charged with the wafers 200 remains loaded to the
inside of the processing chamber 201 (boat load). At this time, the
pressure in the processing chamber 201 is measured by the pressure
sensor 245, and the pressure adjustment unit 242 is feed-back
controlled on the basis of the measured pressure. In addition, the
processing chamber 201 is heated by the heater 206 so as to have a
desired temperature, that is, the second temperature. At this time,
the conductivity status to the heater 206 is feed-back controlled
on the basis of the temperature information detected by the
temperature sensor 263, such that the processing chamber 201 has a
desired temperature distribution. When the pressure and the
temperature in the processing chamber 201 reach the second pressure
and the second temperature, respectively, control so as to maintain
the pressure and the temperature is performed.
[0078] Note that, it is preferable that the second pressure be
equal to the first pressure. In other words, when a transition is
made from the first step (thin film etching process) to the second
step (treatment process), it is preferable that the pressure in the
processing chamber 201 be maintained at a pressure equal to the
first pressure without being changed.
[0079] Meanwhile, it is preferable that the second temperature be
equal to or higher than the first temperature. In other words, when
a transition is made from the first step (thin film etching
process) to the second step (treatment process), it is preferable
that the temperature in the processing chamber 201 be not changed
and maintained at a temperature equal to the first temperature, or
changed to a temperature which is higher than the first
temperature.
[0080] If the second pressure is set to a pressure equal to the
first pressure and the second temperature is set to a temperature
equal to the first temperature, the step of changing the pressure
and the temperature in the processing chamber 201 to the second
pressure and the second temperature will be eliminated.
[0081] Subsequently, F.sub.2 gas, as the cleaning gas, is supplied
from the F.sub.2 gas supply source 274, as the cleaning gas supply
source, to the inside of the processing chamber 201, in the state
where the temperature and the pressure in the processing chamber
201 are maintained at the second temperature and the second
pressure, respectively. Specifically, F.sub.2 gas is supplied from
the F.sub.2 gas supply source 274 to the inside of the cleaning gas
supply tubes 232e, 232f, respectively, by the valves 262e, 261e,
262f, and 261f being opened. F.sub.2 gas is controlled by the MFCs
241e, 241f respectively so as to have desired flow rates, and then
passes through the cleaning gas supply tubes 232e, 232f, and by way
of the processing gas supply tubes 232a, 232b, and is introduced
via the nozzles 230a, 230b to the inside of the processing chamber
201.
[0082] At this time, N.sub.2 gas may be supplied from the N.sub.2
gas supply source 273 as the inert gas supply source to the inside
of the processing chamber 201 simultaneously, so as to dilute
F.sub.2 gas as the cleaning gas. In this case, for example, N.sub.2
gas is supplied from the N.sub.2 gas supply source 273 to the
inside of the inert gas supply tubes 232c, 232d, respectively, by
the valves 262c, 261c, 262d, and 261d being opened. N.sub.2 gas is
controlled by the MFCs 241c, 241d so as to have desired flow rates,
and then passes through the inert gas supply tubes 232c, 232d, and
by way of the processing gas supply tubes 232a, 232b, and is
introduced via the nozzles 230a, 230b to the inside of the
processing chamber 201. N.sub.2 gas is mixed with F.sub.2 in the
processing gas supply tubes 232a, 232b. The concentration of
F.sub.2 gas can also be controlled by controlling the flow rate of
N.sub.2 gas supplied.
[0083] Note that, when a transition is made from the first step
(thin film etching process) to the second step (treatment process),
the valves 262e, 261e, 262f, and 261f, and the valves 262c, 261c,
262d, and 261d may be kept opened so as to maintain supply of
F.sub.2 gas or diluted F.sub.2 gas to the inside of the processing
chamber 201.
[0084] F.sub.2 gas or diluted F.sub.2 gas introduced to the inside
of the processing chamber 201 goes up inside the processing chamber
201, flows via the upper end opening of the inner tube 204 to the
cylindrical space 250, flows down in the cylindrical space 250, and
subsequently, is exhausted from the exhaust pipe 231. When F.sub.2
gas or diluted F.sub.2 gas passes through the inside of the
processing chamber 201, it gets contact with the adhered materials,
such as, minute quartz powders adhered to the inside of the
processing chamber 201, and remaining silicon nitride films, and
with the surfaces of the quartz members (such as the process tube
203, the boat 217, or the like) in the processing chamber 201, or
the like. At this time, the adhered materials, such as quartz
powders, the remaining silicon nitride films, or the like, are
removed by the thermo-chemical reaction, and the surfaces of the
quartz members in the processing chamber 201 are made smooth by
being etched slightly. Specifically, the adhered materials are
removed by the etching reaction between active species generated by
thermal decomposition of F.sub.2 gas with the adhered materials,
and between active species and the surfaces of the quartz member,
whereby the surfaces of the quartz members are made smooth.
[0085] When the processing time which has been set in advance
passes and thus the second step (treatment process) is completed,
supply of F.sub.2 gas is stopped. In other words, supply of F.sub.2
gas from the F.sub.2 gas supply source 274 to the inside of the
processing chamber 201 is stopped, by the valves 262e, 261e, 262f,
and 261f being closed. Subsequently, the valves 262c, 261c, 262d,
and 261d are opened, and then N.sub.2 gas is exhausted from the
exhaust pipe 231 while being supplied from the N.sub.2 gas supply
source 273 to the inside of the processing chamber 201, whereby the
inside of the processing chamber 201 is purged. Next, the
atmosphere in the processing chamber 201 is replaced by N.sub.2
gas, and the pressure in the processing chamber 201 returns to the
normal pressure.
[0086] Note that, the conditions for etching a thin film in the
first step (thin film etching process) are exemplified as
follows:
[0087] first temperature: 350 to 450.degree. C.,
[0088] first pressure: 6650 Pa (50 Torr) to 26600 Pa (200 Torr),
preferably not less than 13300 Pa (100 Torr) and not more than
19950 Pa (150 Torr),
[0089] F.sub.2 gas supply flow rate: 0.5 to 5 slm,
[0090] N.sub.2 gas supply flow rate: 1 to 20 slm.
Etching of a thin film is performed by maintaining each of the
etching conditions to a constant value within each specified
range.
[0091] Meanwhile, the processing conditions in the second step
(treatment process) are exemplified as follows:
[0092] second temperature: 400 to 500.degree. C.,
[0093] second pressure: 6650 Pa (50 Torr) to 26600 Pa (200 Torr),
preferably not less than 13300 Pa (100 Torr) and not more than
19950 Pa (150 Torr),
[0094] F.sub.2 gas supply flow rate: 0.5 to 5 slm,
[0095] N.sub.2 gas supply flow rate: 1 to 20 slm
Processing is performed by maintaining each of the processing to a
constant value within each specified range.
[0096] When the cleaning step, that is, the first step (thin film
etching process) and the second step (treatment process) is
completed, the thin film formation process will be resumed.
[0097] (4) Verification, Consideration, and Advantageous Effects of
the Cleaning Method According to the Present Embodiment
[0098] FIG. 6 shows the results of verification on the temperature
dependency of the etching rate and the selection ratio in the
cleaning method according to the present embodiment.
[0099] FIG. 6A is a graph showing temperature dependency of an
etching rate of silicon nitride film, an etching rate of quartz,
and a selection ratio (the etching rate of silicon nitride film/the
etching rate of quartz), respectively. FIG. 6B is a table showing
the data on which the graph is based. In FIG. 6A, the left vertical
axis shows the etching rates of silicon nitride film and quartz
(.ANG./min), and the right vertical axis shows the selection ratio
(the etching rate of silicon nitride film/the etching rate of
quartz). The horizontal axis shows the temperature in the
processing chamber 201. In the graphs, black dots show the etching
rates of silicon nitride film, and white dots show the etching
rates of quartz, and the "+" marks show the selection ratios. A
silicon nitride film subject to etching was formed under the
processing conditions in the range exemplified in the
above-described embodiment. Etching was performed by changing the
temperature to 300.degree. C., 350.degree. C., 400.degree. C.,
450.degree. C., and 500.degree. C. Other etching conditions than
temperature were set to: pressure: 100 Torr, F.sub.2 flow rate: 2
slm, the N.sub.2 flow rate: 8 slm, and F.sub.2 concentration
(F.sub.5/(F.sub.2+N.sub.2)): 20%.
[0100] It is found from FIG. 6 that both the etching rate of
silicon nitride film and the etching rate of quartz increase as the
temperature increases, and that, on the contrary, the selection
ratio decreases as the temperature increases.
[0101] It is also found that, etching of silicon nitride hardly
progresses at a temperature of approx. 300.degree. C., and that it
sufficiently advances at a temperature not less than 350.degree. C.
enabling a silicon nitride film to be etched at an adequate etching
rate.
[0102] It is found from that, etching of quartz does not progress
much at a temperature less than 400.degree. C., such as 300.degree.
C., 350.degree. C., or the like, and that it sufficiently advances
at a temperature not less than 400.degree. C. and not more than
450.degree. C., enabling quartz to be etched at an adequate etching
rate, although the etching rate of quartz is lower than the etching
rate of silicon nitride film.
[0103] In addition, at 450.degree. C., the selection ratio is
approx. 1 (1.2) and the etching rate of silicon nitride film is
substantially equal to the etching rate of quartz. Based on this,
it is found that silicon nitride film and quartz are etched
equally.
[0104] In addition, at a temperature higher than 450.degree. C.,
the selection ratio is less than 1 (for example, 0.8 at 500.degree.
C.) and the etching rate of silicon nitride film is lower than the
etching rate of quartz. Based on this, it is found that quartz is
etched more than silicon nitride film.
[0105] In addition, at a temperature not more than 450.degree. C.,
the selection ratio is not less than 1 (for example, 1.4 at
400.degree. C. and 1.5 at 350.degree. C.) and the etching rate of
silicon nitride film is higher than the etching rate of quartz.
Based on this, it is found that silicon nitride film is etched more
than quartz.
[0106] From the above-described verification results, the
followings are found. It is preferable that the temperature in the
processing chamber 201 in the first step (thin film etching
process), that is, the first temperature, be not less than
350.degree. C. and not more than 450.degree. C. As described above,
etching of silicon nitride hardly progresses when setting the
temperature in the processing chamber 201 to approx. 300.degree.
C., while etching of silicon nitride can sufficiently progress when
setting the temperature to not less than 350.degree. C. enabling
silicon nitride film to be etched at an adequate etching rate.
[0107] In addition, as described above, the selection ratio (the
etching rate of silicon nitride film with respect to the etching
rate of quartz) is less than 1 if the temperature in the processing
chamber 201 is set to higher than 450.degree. C., while the
selection ratio not less than 1 can be acquired if the temperature
be set not more than 450.degree. C., whereby silicon nitride film
is etched more than quartz. As a result, the damage on the quartz
member in the processing chamber 201 in the first step can be
reduced. Actually, the deposited materials containing silicon
nitride film sometimes cannot be uniformly adhered on the inside of
the processing chamber 201 to be cleaned. For example, the film
thickness of the adhered material is small or large locally. In
addition, the etching rates of the adhered material can sometimes
differ depending on locations because of non-uniform surface
temperature of the inner wall of the processing chamber 201 and
because of non-uniform pressure of the cleaning gas in the
processing chamber 201. In such cases, if all deposited materials
adhered to the inside of the processing chamber 201 are to be
removed by etching, the surfaces of a part of the inner wall of the
processing chamber 201 made of quartz glasses (SiO.sub.2), or the
like, can be sometimes exposed to the cleaning gas for a long
period of time, which can lead to the damage. It is effective to
increase the selection ratio in order to reduce the damage.
[0108] It is found from the above description that, by setting the
first temperature to a value within the above-described range, a
silicon nitride film can be etched at an adequate etching rate
while the damage on the quartz member in the processing chamber 201
being suppressed.
[0109] In addition, it is preferable that the temperature in the
processing chamber 201, that is, the second temperature be not less
than 400.degree. C. and not more than 500.degree. C. in the second
step (treatment process). As described above, while etching of
quartz does not progress much if the temperature in the processing
chamber 201 is set to less than 400.degree. C., adequate etching
rate for quartz can be acquired if the temperature is set to not
less than 400.degree. C. Note that, etching of silicon nitride also
sufficiently advances at this temperature. Therefore, it is
possible to remove the adhered materials, such as, minute quartz
powders remaining and adhered on the inside of the processing
chamber 201 after the first step, remaining silicon nitride films,
or the like. At the same time, it is also possible to make the
surfaces of the quartz members in the processing chamber 201 smooth
by slightly etching them, thereby to suppress increase in the
effective surface area in the processing chamber 201. By this
configuration, it is possible to suppress generation of foreign
substances in the processing chamber 201, and also possible to
suppress decrease in the film formation rate in the thin film
formation process which is immediately after the cleaning process,
i.e., the first step (thin film etching process) and the second
step (treatment process). Note that, in the case where the
temperature in the processing chamber 201 is set to not less than
400.degree. C. and not more than 450.degree. C., etching of quartz
can sufficiently progress, although the etching rate of quartz is
equal to or slightly lower than the etching rate of silicon nitride
film. In the case where the temperature in the processing chamber
201 is set to not less than 450.degree. C. and not more than
500.degree. C., the etching rate of quartz becomes greater than the
etching rate of silicon nitrite film, enabling making the surfaces
of the quartz members, such as the process tube 203, the boat 217,
or the like, smooth more quickly.
[0110] Meanwhile, if the temperature in the processing chamber 201
is set to greater than 500.degree. C., there is a concern on
corrosion of metal members in the processing chamber 201 or in the
gas flow passage, such as the manifold 209, the seal cap 219, the
rotational axis 255, the exhaust pipe 231, the pressure adjustment
unit 242, or the like. However, it is possible to suppress
corrosion of the metal members by setting the temperature to not
more than 500.degree. C.
[0111] It is found from the above that, by setting the second
temperature to a value within the above-described range, the
adhered materials remaining on the inside of the processing chamber
201 after the first step and the surfaces of the quartz members can
be properly etched, while corrosion of the metal members in the
processing chamber 201 are suppressed.
[0112] Meanwhile, both the temperature (first temperature) in the
processing chamber 201 in the first step (thin film etching
process), and the temperature (second temperature) in the
processing chamber 201 in the second step (treatment process), may
be set to temperatures not less than 400.degree. C. and not more
than 450.degree. C. This temperature region enables the etching
reaction of a silicon nitride film to sufficiently progress, and
also enables the etching reaction of quartz to progress. In this
case, the etching rate of quartz is equal to or slightly lower than
the etching rate of silicon nitride film. In other words, it would
be safe to say that this temperature region is an intermediate
temperature region which enables a silicon nitride to be etched
equally or slightly superior to quartz.
[0113] It is found from the above that, in the temperature region
not less than 400.degree. C. and not more than 450.degree. C., both
etching of silicon nitride film and etching of quartz can be
performed substantially equally, and the first step and the second
step can be continuously performed at a same temperature. In other
words, by making the first temperature and the second temperature
substantially equal in this temperature region, the cleaning can be
performed stably without the need for changing the temperature in
the processing chamber 201 when a transition is made from the first
step to the second step, and thus generating no waiting time
associated with the change in the temperature.
[0114] Alternatively, the temperature (first temperature) in the
processing chamber 201 in the second step (treatment process) may
be set higher than the temperature (second temperature) in the
processing chamber 201 in the first step (thin film etching
process). Specifically, it is possible to set the first temperature
such that it has the selection ratio (the etching rate of silicon
nitride film with respect to the etching rate of quartz) more than
1, and to set the second temperature such that it has the selection
ratio less than 1. In other words, silicon nitride film can be
etched more than quartz in the first step (thin film etching
process), and quartz can be etched more than silicon nitride film
in the second step (treatment process). As a result, compared with
the case where the first step and the second step are continuously
performed at a same temperature, over-etching of quartz can be
suppressed. Specifically, over-etching of quartz can be suppressed
because the selection ratio is more than 1 in the first step. In
addition, in the second step, the etching rate of quartz can be
further enhanced, whereby the adhered materials such as minute
quartz powders remaining and adhered to the inside of the
processing chamber 201, remaining silicon nitride films, or the
like, can be quickly removed, and the surfaces of the quartz
members in the processing chamber 201 can be quickly and properly
etched, whereby the surfaces can be made smooth.
[0115] Note that, it is preferable that the pressure (first
pressure) in the processing chamber 201 in the first step (thin
film etching process) and the pressure (second pressure) in the
processing chamber 201 in the second step (treatment process) be
set to not less than 50 Torr and not more than 200 Torr. It is
possible to enable etching to sufficiently progress and increasing
etching uniformity, if the first pressure and the second pressure
are set to values within this range. If the first and second
pressures are too low, the etching rates will become low in the
first and second steps, disabling etching to sufficiently advance.
Etching can sufficiently progress by setting these pressures to not
less than 50 Torr (6650 Pa). On the other hand, if the first and
second pressures are too high, etching will become unbalanced
although the etching rate increases leading to non-uniform etching.
Etching uniformity can be enhanced by setting the pressures to not
more than 200 Torr (26600 Pa).
[0116] According to the present embodiment, the above-described
advantageous effects can be obtained, since the conditions such as
the first temperature, the second temperature, and the like, are
set as described above on the basis of the above-described
verification results. Specifically, since the first temperature is
set to a value within the above-described range, a silicon nitride
film can be etched at an adequate etching rate, while the damage on
the quartz members in the processing chamber 201 is suppressed.
Further, since the second temperature is set to a value within the
above-described range, the adhered materials remaining on the
inside of the processing chamber 201 after the first step, and the
surfaces of the quartz members can be properly etched, while
corrosion of the metal members in the processing chamber 201 is
suppressed.
[0117] Further, according to the present embodiment, in the first
step (thin film etching process) and the second step (treatment
process), as the cleaning gas, hydrogen-containing gas, such as HF
gas, H.sub.2 gas, or the like, is not supplied to the inside of the
processing chamber 201. Instead, F.sub.2 gas solely or F.sub.2 gas
diluted by an inert gas solely is supplied to the inside of the
processing chamber 201. As a result, HF-induced corrosion of the
metal members in the processing chamber 201 or in the gas flow
passage, such as, the manifold 209, the seal cap 219, the
rotational axis 255, the exhaust pipe 231, the pressure adjustment
unit 242, or the like, can be suppressed, and generation of
metallic contamination in the processing chamber 201 can be
suppressed. Further, HF-induced erosion of the quartz members in
the processing chamber 201 (the process tube 203, the boat 217, or
the like) can be suppressed, and breakage of the quartz members can
be suppressed.
[0118] Further, according to the present embodiment, there is no
need for performing the seasoning process, in order to suppress
generation and dispersion of foreign substances after the cleaning,
and in order to suppress decrease in the film formation rate in the
thin film formation process after the cleaning. In other words,
there is no need for supplying processing gas to the inside of the
processing chamber 201 in the state where the wafers 200 have not
been loaded to the processing chamber 201 after the cleaning, so as
to form a thin film (pre-coat) on the inner wall, or the like, of
the processing chamber 201. Conventionally, the seasoning process
took a long time, which partially contributed to increase in the
down-time of the substrate processing apparatus. However, according
to the present embodiment which eliminates the needs for performing
the seasoning process, the down-time of the substrate processing
apparatus can be greatly reduced.
EXAMPLES
Example 1
[0119] As Example 1 of the present invention, a case where the
cleaning is performed, with the temperature (second temperature) in
the processing chamber 201 in the second step (treatment process)
being set higher than the temperature (first temperature) in the
processing chamber 201 in the first step (thin film etching
process) will be described. FIG. 2 is a graph chart showing the
sequence and the cleaning conditions of the cleaning step according
to the Example 1 of the present invention.
[0120] In the thin film formation process of Example 1, a silicon
nitride film was formed with use of SiH.sub.2Cl.sub.2 (DCS) gas and
NH.sub.3 gas, as the processing gas, in accordance with the same
method and conditions as those in the above-described embodiment.
The film thickness of the silicon nitride to be formed by a single
thin film formation process was set to 500 .ANG.. After the thin
film formation process was performed 16 times (every time when
cumulative film thickness becomes 8000 .ANG.), the cleaning process
(thin film etching and treatment) was performed. Meanwhile, the
temperature in the processing chamber 201 was set to 650.degree. C.
and the pressure in the processing chamber 201 was set to the
atmospheric pressure, after completion of 16-times of the thin film
formation process (when the processed wafers 200 were
unloaded).
[0121] In the cleaning step of the Example 1, first, the processing
chamber 201 was vacuum evacuated, while the temperature in the
processing chamber 201 was decreased to 400.degree. C.
Subsequently, the first step (thin film etching process) was
performed, with the temperature (first temperature) in the
processing chamber 201 being set to 400.degree. C., and
subsequently, the second step (treatment process) was performed,
with the temperature (second temperature) in the processing chamber
201 being set to 450.degree. C. Note that, the pressure in the
processing chamber 201 was set to 19998 Pa (150 Torr), the supply
flow rate of F.sub.2 gas was set to 2.0 slm, and the supply flow
rate of N.sub.2 gas was set to 8.0 slm, in the first step (thin
film etching process) and the second step (treatment process).
After completion of the cleaning step, the processing chamber 201
was purged, the pressure in the processing chamber 201 was
increased to the atmospheric pressure, and the temperature in the
processing chamber 201 was increased to 650.degree. C.
[0122] The 16 times of thin film formation processes and the
subsequent cleaning step were assumed as 1 cycle. Next, this cycle
was repeated a plurality of times. Every time the thin film
formation process is completed, the amount of increased foreign
substances in the processing chamber 201 was measured, and the film
formation rate of silicon nitride film was also measured.
Example 2
[0123] As Example 2 of the present invention, a case where the
cleaning step was performed, with both the temperature (first
temperature) in the processing chamber 201 in the first step (thin
film etching process) and the temperature (second temperature) in
the processing chamber 201 in the second step (treatment process)
being set to 450.degree. C., will be described. FIG. 3 is a graph
chart showing the sequence and the cleaning conditions of the
cleaning according to the Example 2 of the present invention. Other
conditions are the same as those in the Example 1.
[0124] As is the case with the Example 1, the 16 times of the thin
film formation processes and the subsequent cleaning step were
assumed as 1 cycle. Next, the cycle was repeated a plurality of
times. Every time the thin film formation process is completed, the
amount of increased foreign substances in the processing chamber
201 was measured, and the film formation rate of silicon nitride
film was also measured.
[0125] In both the Example 1 and the Example 2, it was confirmed
that increase of the foreign substances in the processing chamber
201 was suppressed. In the conventional dry etching method, in the
case where the seasoning process in the processing chamber 201 was
not performed, the number of the increased foreign substances in
the processing chamber 201 was 50 or more. On the contrary, in each
of the Example 1 and the Example 2, it was confirmed that the
number of the increased foreign substances in the processing
chamber 201 was suppressed to approx. 20 to 30.
[0126] FIG. 4 is a graph chart showing the validation data on the
amount of foreign substances generated according to the Example 2
of the present invention. The vertical axis in FIG. 4 shows the
number of increased foreign substances (particles) with the
particle diameter not less than 0.13 .mu.m (unit: piece) at each
measurement position in the processing chamber 201, and the
horizontal axis shows the number of the thin film formation
processes (number of batches) performed. The mark ".largecircle."
shows the number of increased foreign substances at a top position
(upper portion) of the processing chamber 201, and the mark " "
shows the number of increased foreign substances at a bottom
position (lower portion) of the processing chamber 201. It is found
from FIG. 4 that increase of the foreign substances in the
processing chamber 201 was suppressed to approx. 20 to 30.
[0127] In addition, in both the Example 1 and the Example 2, it was
confirmed that decrease in film formation rate of silicon nitride
film was suppressed. In the conventional dry etching method, the
film formation rate of silicon nitride film immediately after the
dry etching sometimes dropped by more than .+-.2%. On the contrary,
in the Example 1 and the Example 2, decrease in film formation rate
of silicon nitride film was within .+-.0.96%, and it was observed
that decrease in film formation rate immediately after the cleaning
step was suppressed.
[0128] FIG. 5 is a graph chart showing the validation data on
reproducibility of the film formation rate according to the Example
2 of the present invention. The vertical axis in FIG. 5 shows the
film formation rate of silicon nitride film (unit: .ANG./min), and
the horizontal axis shows the number of the thin film formation
processes (number of batches) performed. It is found from FIG. 5
that decrease in film formation rate of silicon nitride film was
within .+-.0.96%, and that decrease in film formation rate
immediately after the cleaning step was suppressed.
[0129] In both the Example 1 and the Example 2, it was confirmed
that no corrosion was generated in the metal members, for example,
such as the manifold 209, the seal cap 219, the rotational axis
255, the exhaust pipe 231, the pressure adjustment unit 242, or the
like, in the processing chamber 201 or in the gas flow passage
after the cleaning (etching and treatment). In addition, it was
confirmed that no erosion or breakage of the quartz members in the
processing chamber 201 (the process tube 203, the boat 217, or the
like) was generated.
Example 3
[0130] As Example 3 of the present invention, a case in which the
cleaning in the above-described embodiment (Example 1, Example 2)
and LTP (Low Temperature Purge) are combined will be described. The
LTP, also called as the low temperature purge, herein refers to
purge of the inside of the processing chamber 201 with gas, while
applying a thermal impact onto the thin film deposited on the
inside of the processing chamber 201 by decreasing a temperature in
the processing chamber 201, so as to forcibly generate a crack in
the thin film and forcibly peel the adhered material adhered on the
inside of the processing chamber with a weak adhesive force.
[0131] In the meantime, the above-described embodiment (Example 1,
Example 2) is an art based on the assumption that a substrate
processing apparatus which performs the dry cleaning process is
operated. However, when a practical operation of the apparatus is
considered, the thin films accumulated on the inside of the
processing chamber 201 increase film stress as the cumulative film
thickness increases, leading to generation of cracks. When external
factors (heat, pressure, friction) are added to this, the film can
peel off or drop, leading to increased particles as foreign
substances. Accordingly, particularly in the case where the film
thickness of the thin film to be performed in a single thin film
formation process is large, or the like, the dry cleaning process
need be performed with a relatively short cycle period.
Accordingly, the operation rate of the substrate processing
apparatus can sometimes drop.
[0132] FIG. 8 shows transition of particles generated after the dry
cleaning process. The vertical axis in FIG. 8 shows the number of
the increased particles with the particle diameter not less than
0.13 .mu.m at each measurement positions in the processing chamber
201 (unit: piece), and the horizontal axis shows the number of the
thin film formation processes (number of batches) performed after
the dry cleaning was performed, that is, the number of runs of
Si.sub.3N.sub.4 film formations (number of processings in batch).
The mark " " shows the number of increased foreign substances at
the top position (upper portion) in the processing chamber 201, and
the mark ".largecircle." shows the number of increased foreign
substances at the bottom position (lower portion) in the processing
chamber 201. Note that, in the thin film formation process, an
Si.sub.3N.sub.4 film of 0.15 .mu.m per run was formed with use of
DCS gas and NH.sub.3 gas, as the processing gas, in accordance with
the same method and conditions as those in the above-described
embodiment. It is found from FIG. 8 that, although the particles
increased slightly and stably immediately after the dry cleaning,
the particles increased sharply at the 12.sup.th run of the
Si.sub.3N.sub.4 film formation (which is equivalent to the
cumulative film thickness 2 .mu.m), and that the dry cleaning
process need be performed when the cumulative film thickness is
less than 2 .mu.M. Based also on this fact, it is found that,
particularly in the case where the film thickness of the thin film
to be formed per thin film formation process is large, the dry
cleaning process need be performed with a short cycle period, and
accordingly the operation rate of the apparatus drops greatly.
[0133] Therefore, the task is to achieve the apparatus operation by
performing the dry cleaning process with a long cycle period so as
to suppress generation of particles for a long time and enhance the
operation rate of the apparatus. Therefore, in Example 3,
description will be given on the dry cleaning art (apparatus
operation) which enables maintaining a high operation rate of the
apparatus by combined use of LTP in the apparatus operation,
assuming that the dry cleaning process is performed.
[0134] In the present Example, the process of purging the inside of
the processing chamber 201 with gas while decreasing the
temperature in the processing chamber 201 during the thin film
formation process or immediately after the thin film formation
process, in the state where the wafers 200 are present in the
processing chamber 201 or in the state where the wafers 200 are not
present in the processing chamber 201, thereby to apply a thermal
impact on the thin films accumulated on the inside of the
processing chamber 201 so as to forcibly generate cracks in the
thin films and to forcibly peel the adhered material with a weak
adhesive force, is performed, periodically or every time the thin
film formation process is performed. By this configuration, the
cumulative film thickness until the thin films accumulated on the
inside of the processing chamber 201 start peeling off or dropping
can be increased, and the cleaning cycle can be made longer. Next,
at the time point when the thickness of the thin films accumulated
on the inside of the processing chamber 201 reaches a predetermined
thickness before the thin films start peeling off or dropping,
cleaning of the inside of the processing chamber 201 is performed.
In the cleaning process, the step, as the first step, of removing a
thin film accumulated on the inside of the processing chamber 201
by supplying a fluorine gas solely or a fluorine gas diluted by an
inert gas solely, as the cleaning gas, to the inside of the
processing chamber 201 heated to the first temperature (thin film
etching process), and, the step, as the second step, of removing
adhered materials remaining in the processing chamber 201 after
removing the thin film, by supplying a fluorine gas solely or a
fluorine gas diluted by an inert gas solely, as the cleaning gas,
to the inside of the processing chamber 201 heated to the second
temperature (treatment process) are performed. By this
configuration, the life of the quartz members such as the process
tube 203, or the like, can be extended, which does not require
maintenance, for a long period of time, involving exchange of the
quartz members or the like.
[0135] In the LTP process, it is preferable that the temperature in
the processing chamber 201 be sharply decreased (fluctuated) from
the film formation temperature exceeding 600.degree. C., to a low
temperature of 200 to 400.degree. C. at which cracks occur, during
the thin film formation process, or between the thin film formation
process and the subsequent thin film formation process. When the
temperature in the processing chamber 201 is sharply decreased, it
is preferable that the inside of the processing chamber 201 be
forcibly cooled (rapidly cooled) by causing cooling medium, such as
an air, N.sub.2, or the like, to flow to the outside of the
processing chamber 201, while the high-temperature atmospheric gas
at the outside of the processing chamber 201 is discharged.
[0136] In this case, as shown in FIG. 10, it is preferable that a
forced-cooling mechanism (rapid-cooling mechanism) 400 be provided
outside of the processing chamber 201 (processing furnace 202) so
as to cover the processing chamber 201, and that the controller 240
control the forced-cooling mechanism 400, the heater 206, the purge
gas supply system, and the exhaust system, such that the inside of
the processing chamber 201 is purged with gas, while the
temperature in the processing chamber 201 is decreased by forcibly
cooling the inside of the processing chamber 201. The
forced-cooling mechanism 400 is provided so as to cover the process
tube 203 and the heater 206. The forced-cooling mechanism 400
includes: a heat insulation cover 410 provided so as to cover the
process tube 203 and the heater 206, a supply line 420 provided in
communication with the internal space of the heat insulation cover
410, and an exhaust line 430 in communicated with the internal
space of the heat insulation cover 410 via an exhaust hole 440 in
the ceiling portion of the heat insulation cover 410. The supply
line 420 is provided with an intake blower 450 and a shutter 460.
The exhaust line 430 is provided with a shutter 470, a radiator
480, and an exhaust blower 490. The forced-cooling mechanism 400 is
electrically connected to the temperature controller 238 configured
to control the forced-cooling mechanism 400 at desired timings. In
the LTP process, when the temperature in the processing chamber 201
is decreased by forcibly cooling the inside of the processing
chamber 201 by means of the forced-cooling mechanism 400, the
shutters 460, 470 are released and the high-temperature atmospheric
gas in the heat insulation cover 410 is exhausted by the exhaust
blower 490. At the same time, cooling medium such as air, N.sub.2,
or the like, is introduced to the inside of the heat insulation
cover 41 by the intake blower 450. Note that, in FIG. 10, elements
which are the substantially same as the elements described with
reference to FIG. 7 are given with the same numerals as those in
FIG. 7, and the description thereof will be omitted.
[0137] Note that, the LTP process can also be performed, under the
control by the controller 240 of the heater 206, and the purge gas
supply and exhaust systems, such that the inside of the processing
chamber 201 is purged with gas while the temperature in the
processing chamber 201 is decreased, without use of the
forced-cooling mechanism 400. However, it is more preferable that
the temperature in the processing chamber 201 be sharply fluctuated
with use of the forced-cooling mechanism 400, because a thermal
impact on the thin films accumulated on the inside of the
processing chamber 201 can be made larger, and the particle
discharge effect can be enhanced. In addition, the LTP process may
be performed every time the thin film formation process is
performed, or may be performed periodically at certain intervals.
With the total particle discharge effect being taken into
consideration, it is preferable that the LTP process be performed
every time the thin film formation process is performed.
[0138] In the cleaning step, as is the case with the
above-described embodiment, it is preferable that, F.sub.2 gas
solely, or F.sub.2 gas diluted by an inert gas such as N.sub.2
(nitrogen), Ar (argon), He (helium), or the like solely, be
supplied as the cleaning gas. In addition, in the thin film etching
process, as the first step, it is preferable that the thin films
accumulated on the inside of the processing chamber 201 be removed,
while the first temperature is maintained at a certain temperature
within the temperature range from not less than 350.degree. C. to
not more than 450.degree. C. In addition, in the treatment process,
as the second step, it is preferable that the adhered materials
remaining in the reaction chamber be removed, while the second
temperature is maintained at a certain temperature within the
temperature range from not less than 400.degree. C. to not more
than 500.degree. C. Note that, in the thin film etching process, as
the first step, and in the treatment process, as the second step,
the first and second temperatures may be set to a constant
temperature within the temperature range from not less than
400.degree. C. to not more than 450.degree. C., or the second
temperature in the treatment process as the second step may be set
to a temperature equal to or higher than the first temperature in
the thin film etching process as the first step.
[0139] Hereinafter, the process characteristics acquired in the
substrate processing apparatus shown in FIG. 10, that is, the CVD
apparatus for Si.sub.3N.sub.4 film formation including the
forced-cooling mechanism 400, with the method in the Example 3 of
the present invention being applied, will be described. FIG. 9
shows stability of particles after the dry cleaning process
according to the Example 3. The vertical axis in FIG. 9 shows
increase of the particles with the particle diameter not less than
0.13 .mu.m in the processing chamber 201 at each measurement
position (unit: piece), and the horizontal axis shows the number of
the thin film formation processes (number of batches) performed,
that is, the number of Si.sub.3N.sub.4 film formations (number of
processings in batch) after the dry cleaning was performed. In
addition, the mark " " in FIG. 9 shows the number of increased
foreign substances at the top position (lower portion) of the
processing chamber 201, and the mark ".largecircle." shows the
number of increased foreign substances at the bottom position
(lower portion) of the processing chamber 201. Note that, in the
thin film formation step, an Si.sub.3N.sub.4 film of 0.15 .mu.m per
run was formed, with use of DCS gas and NH.sub.3 gases as the
processing gas, in accordance with the same method and conditions
as those in the above-described embodiment. In addition, the dry
cleaning was performed in the similar method and conditions as
those in the Example 2. The LTP was performed, every time the thin
film formation process was performed, in the state where no wafers
200 were present in the processing chamber 201, by decreasing the
temperature in the processing chamber 201, from a film formation
temperature of 650 to 800.degree. C., to 400.degree. C., at the
temperature decrease rate 20.degree. C./min, and at the same time,
by exhausting N.sub.2 gas by means of the exhaust system, while the
purge-gas supply system is supplying N.sub.2 in a large amount at
the flow rate 20 L/min or higher to the inside of the processing
chamber 201, in the state where the pressure in the processing
chamber 201 is set to the atmospheric pressure. At this time, the
lower end of the manifold 209 is sealed by the furnace opening
shutter 219a via the O ring 220c. Note that, the LTP process was
performed in parallel with the wafer cooling and wafer discharge,
after the boat 217 holding the processed wafers 200 was unloaded
from the inside of the processing chamber 201 (boat unload). In
FIG. 8, where the LTP is not used together, the particles sharply
increased at the 12.sup.th run of the Si.sub.3N.sub.4 film
formation (which is equivalent to the cumulative film thickness 2
.mu.m). However, in FIG. 9 where the method in the Example 3 is
applied, there was no significant increase of the particles, at
least from immediately after the dry cleaning process was performed
to the 50.sup.th run of the Si.sub.3N.sub.4 film formation (which
is equivalent to the cumulative film thickness 8 .mu.m), and thus a
favorable data was obtained.
[0140] According to the present Example, by adding the LTP process
to the dry cleaning technologies as the basis during or after the
thin film formation process, it is possible to suppress generation
of particles associated with the increased cumulative film
thickness after the dry cleaning, and to extend and the dry
cleaning cycle period. Therefore, it is possible to maintain a high
operation rate of the apparatus, greatly contributing to
improvement in productively.
[0141] Conventionally, in the specifications in which the dry
cleaning process is not performed (specifications which perform
part exchange, and wet cleaning), and only the LTP process is
performed during or after the thin film formation process, work
requiring manual labor, such as attachment and detachment operation
of component members in the reaction furnace, the cleaning
operation, or the like, is necessary, at the time point when a
certain cumulative film thickness is reached. However, in the
present Example, only the thin film formation process, the LTP
process, and the dry cleaning process need be performed, which
provides good maintenance performance.
[0142] Furthermore, the extended dry cleaning cycle period by use
of the LTP process as well as the suppression of damage on the
quartz members, such as the process tube, by means of the dry
cleaning process with use of F.sub.2 gas, enables extending the
life of the quartz members compared with the conventional
apparatus, which eliminates the need for maintenance involving
exchange of quartz members, or the like, for a long period of time.
According to the present Example, the device can be made free from
maintenance for a 1-year period or longer after the substrate
processing apparatus starts film formation.
[0143] Furthermore, the LTP process during or after the thin film
formation process generates cracks on the surfaces of the thin
films accumulated on the inside of the processing chamber, which
increases the effective surface area of the cumulative film in the
dry cleaning, and the essential contact area of the cumulative film
with F.sub.2 gas. Accordingly, the etching reaction between F.sub.2
gas with the cumulative film is made easier to progress, which
could contribute also to reduction of the etching time.
[0144] Note that, in the above-described Example 3, description was
given on the case where, F.sub.2 gas solely or F.sub.2 gas diluted
by an inert gas solely is used as the cleaning gas. However, in the
method in Example 3, that is, in the film formation according to
the "LTP+the dry cleaning specification", F.sub.2 may be replaced
by a halogen-based gas, such as ClF.sub.3, NF.sub.3, or the like
(fluorine-based gas), as the cleaning gas.
[0145] Provided that, even in the case of the film formation
according to the "LTP+the dry cleaning specifications", as
described in the embodiment, it is preferable that, F.sub.2 gas
solely or F.sub.2 gas diluted by an inert gas solely be used, as
the cleaning gas, for performing the thin film etching process and
the treatment process. In other words, it is preferable that the
thin film etching process and the treatment process with use of
F.sub.2 gas, be combined with the LTP process.
[0146] Let us image the case where thin film etching process with
use of F.sub.2 gas, ClF.sub.2 gas, NF.sub.3 gas or the like, be
combined with the LTP process (in the case where the treatment
process is not performed after the thin film etching process). In
this case, there are following disadvantages.
[0147] As shown in FIG. 11A, foreign substances, such as quartz
powders, remain on the quartz surfaces after the thin film etching
process ("Cleaning"). The foreign substances are adhered to the
quartz surfaces in an unstable state. In the thin film formation
process ("SiN Deposition"), the thin film is deposited on the
foreign substances. When the LTP process is performed in this
state, when the thin film cracks or peels off, the foreign
substances adhered to the quartz surfaces also crack and peel off.
Further, the adhesion state of the foreign substances onto the
quartz surfaces becomes more unstable, which disables stopping
generation of foreign substances. In addition, because of the
unstable adhesion state of the foreign substances onto the quartz
surfaces, foreign substances are more likely generated, when a thin
film is formed after the LTP ("SiN Deposition).
[0148] On the contrary, in the case where the thin film etching
process and the treatment process using F.sub.2 gas are combined
with the LTP process, the following advantages are obtained.
[0149] As shown in FIG. 11B, after the treatment process
(Treatment) is performed subsequent to the thin film etching
process (Cleaning) is completed, it is possible to prevent foreign
substances from remaining on the quartz surfaces. In other words,
no foreign substances are adhered on the quartz surfaces in an
unstable state. In the thin film formation process (SiN
Deposition), the thin film is deposited on the quartz surfaces on
which no foreign substance is present. When the LTP process is
performed in this state, even if the thin film cracks or peels off,
no foreign substances will be generated since no foreign substances
have been adhered to the quartz surfaces. In addition, also when a
thing film is formed (SiN Deposition) after the LTP, no foreign
substances are generated.
[0150] It is found from the above that, in the case of the film
formation according to the "LTP+the dry cleaning specification", it
is preferable that the thin film etching process and the treatment
process with use of F.sub.2 gas be combined with LTP.
PREFERRED EMBODIMENTS OF THE PRESENT INVENTION
[0151] Hereinafter, preferred embodiments of the present invention
will be added.
[0152] According to one aspect of the present invention, a method
for manufacturing a semiconductor device is provided. The method
includes the steps of: loading a substrate into a processing
chamber; performing a processing of forming a thin film on the
substrate by supplying a processing gas to an inside of the
processing chamber heated to a processing temperature; unloading
the processed substrate out of the processing chamber; and cleaning
the inside of the processing chamber by supplying a cleaning gas to
the inside of the processing chamber, in the state where the
substrate is not present in the processing chamber. The step of
cleaning the inside of the processing chamber includes the steps
of: removing the thin film deposited on the inside of the
processing chamber by supplying a fluorine gas solely or a fluorine
gas diluted by an inert gas solely, as the cleaning gas, to the
inside of the processing chamber heated to a first temperature; and
removing an adhered material remaining on the inside of the
processing chamber after removing the thin film, by supplying a
fluorine gas solely or a fluorine gas diluted by an inert gas
solely, as the cleaning gas, to the inside of the processing
chamber heated to a second temperature.
[0153] It is preferable that the first temperature be set to not
less than 350.degree. C. and not more than 450.degree. C., and the
second temperature should be set to not less than 400.degree. C.
and not more than 500.degree. C.
[0154] It is preferable that both the first and second temperatures
should be set to not less than 400.degree. C. and not more than
450.degree. C.
[0155] It is preferable that the second temperature should be set
to equal to or greater than the first temperature.
[0156] It is preferable that the pressure in the processing chamber
should be set to not less than 6650 Pa (50 Torr) and not more than
26600 Pa (200 Torr), when performing the cleaning (that is, when
removing the thin film and when removing the adhered material).
[0157] It is preferable that the pressure in the processing chamber
should be set to not less than 13300 Pa (100 Torr) and not more
than 19950 Pa (150 Torr) when performing the cleaning (when
removing the thin film and when removing the adhered material).
[0158] It is preferable that the first temperature should be a
temperature at which the thin film is more etched than the member
constituting the processing chamber and the second temperature
should be a temperature at which the member constituting the
processing chamber is more etched than the thin film.
[0159] It is preferable that the first and second temperatures
should be temperatures at which the thin film and the member
constituting the processing chamber is equally etched, or the thin
film is etched slightly more than the member constituting the
processing chamber.
[0160] It is preferable that the member constituting the processing
chamber should include a quartz member, the thin film should be a
silicon nitride film, the first temperature should be a temperature
at which the silicon nitride film is more etched than the quartz
member, and the second temperature should be a temperature at which
the quartz member is more etched than the silicon nitride film.
[0161] It is preferable that the member constituting the processing
chamber should include a quartz member, the thin film should be a
silicon nitride film, and the first and second temperatures should
be temperatures at which the silicon nitride film and the quartz
member are equally etched or the silicon nitride film is etched
slightly more than the quartz member.
[0162] It is preferable that the first temperature should be a
temperature at which the etching rate of the thin film is greater
than the etching rate of the member constituting the processing
chamber and the second temperature should be a temperature at which
the etching rate of the member constituting the processing chamber
is greater than the etching rate of the thin film.
[0163] It is preferable that the first and second temperatures
should be temperatures at which the etching rate of the thin film
and the etching rate of the member constituting the processing
chamber are equal or the etching rate of the thin film is slightly
larger than the etching rate of the member constituting the
processing chamber.
[0164] It is preferable that the member constituting the processing
chamber should include a quartz member, the thin film should be a
silicon nitride film, the first temperature should be a temperature
at which the etching rate of the silicon nitride film is greater
than the etching rate of the quartz member, and the second
temperature should be a temperature at which the etching rate of
the quartz member is greater than the etching rate of the silicon
nitride film.
[0165] It is preferable that the member constituting the processing
chamber should include a quartz member, the thin film should be a
silicon nitride film, and the first and second temperatures should
be temperatures at which the etching rate of the silicon nitride
film and the etching rate of the quartz member are equal, and the
etching rate of the silicon nitride film is slightly larger than
the temperature than the etching rate of the quartz member.
[0166] It is preferable that the member constituting the processing
chamber should include a quartz member and a metal member.
[0167] It is preferable that the member constituting the processing
chamber should include a quartz member and a metal member, the thin
film should be a silicon nitride film, and the adhered material
should include quartz powders.
[0168] It is preferable that the method should further include the
step of: purging the inside of the processing chamber with gas
while applying a thermal impact onto the thin film deposited on the
inside of the processing chamber by decreasing a temperature in the
processing chamber to a temperature lower than the processing
temperature, so as to forcibly generate a crack in the thin film
and forcibly peel the adhered material adhered on the inside of the
processing chamber with a weak adhesive force, in the state where
the substrate is not present in the processing chamber.
[0169] According to another aspect of the present invention, a
method for manufacturing a semiconductor device is provided. The
method includes the steps of: loading a substrate into a processing
chamber; performing a processing of forming a thin film on the
substrate by supplying a processing gas to an inside of the
processing chamber; unloading the processed substrate out of the
processing chamber; and cleaning the inside of the processing
chamber by supplying a cleaning gas to the inside of the processing
chamber. The step of cleaning includes the steps of removing the
thin film deposited on the inside of the processing chamber by
supplying a gas which does not contain a hydrogen-containing gas
but contains a fluorine gas, as the cleaning gas, to the inside of
the processing chamber heated to a first temperature; and removing
an adhered material remaining on the inside of the processing
chamber after removing the thin film by supplying a gas which does
not contain a hydrogen-containing gas but contains a fluorine gas,
as the cleaning gas, to the inside of the processing chamber heated
to a second temperature.
[0170] According to a still another aspect of the present
invention, a method for manufacturing a semiconductor device is
provided. The method includes the steps of: loading a substrate
into a processing chamber; performing a processing of forming a
thin film on the substrate by supplying a processing gas to an
inside of the processing chamber; unloading the processed substrate
out of the processing chamber; and cleaning the inside of the
processing chamber by supplying a cleaning gas to the inside of the
processing chamber. The step of cleaning the inside of the
processing chamber includes the steps of: removing the thin film
deposited on the inside of the processing chamber by supplying a
fluorine gas solely, as the reactive gas, to the inside of the
processing chamber heated to a first temperature; and removing an
adhered material remaining on the inside of the processing chamber
after removing the thin film by supplying a fluorine gas solely, as
the cleaning gas, to the inside of the processing chamber heated to
a second temperature.
[0171] According to a still another aspect of the present
invention, a method for manufacturing a semiconductor device is
provided. The method includes the steps of: loading a substrate
into a processing chamber composed of a member including a quartz
member and a metal member; perform a processing of forming a
silicon nitride film on the substrate by supplying a processing gas
to the inside of the processing chamber; unloading the processed
substrate out of the processing chamber; and cleaning the inside of
the processing chamber by supplying a cleaning gas to the inside of
the processing chamber. The step of cleaning the inside of the
processing chamber includes the steps of: removing the silicon
nitride film deposited on the inside of the processing chamber by
supplying a fluorine gas solely or a fluorine gas diluted by an
inert gas solely, as the cleaning gas, to the inside of the
processing chamber heated to a first temperature; and removing an
adhered material containing quartz powders which remains on the
inside of the processing chamber after removing the silicone
nitride film by supplying a fluorine gas solely or a fluorine gas
diluted by an inert gas solely, as the cleaning gas, to the inside
of the processing chamber heated to a second temperature.
[0172] According to a still another aspect of the present
invention, a method for manufacturing a semiconductor device is
provided. The method includes the steps of: loading a substrate
into a processing chamber composed of a member including a quartz
member and a metal member; performing a processing of forming a
silicon nitride film on the substrate by supplying a processing gas
to an inside of the processing chamber; unloading the processed
substrate out of the processing chamber; and cleaning the inside of
the processing chamber by supplying a cleaning gas to the inside of
the processing chamber, in the state where the substrate is not
present in the processing chamber. The step of cleaning the inside
of the processing chamber includes the steps of: removing a silicon
nitride film deposited on the inside of the processing chamber by
supplying a fluorine gas solely or a fluorine gas diluted by an
inert gas solely, as the cleaning gas, to the inside of the
processing chamber in which a temperature is set to not less than
350.degree. C. and not more than 450.degree. C. and a pressure is
set to not less than 6650 Pa and not more than 26600 Pa; and
removing an adhered material including quarts powders remaining on
the inside of the processing chamber after removing the silicon
nitride film, by supplying a fluorine gas solely or a fluorine gas
diluted by an inert gas solely, as the cleaning gas, to the inside
of the processing chamber in which a temperature is set to not less
than 400.degree. C. and not more than 500.degree. C. and a pressure
is set to not less than 6650 Pa and not more than 26600 Pa.
[0173] According to a still another aspect of the present
invention, a substrate processing apparatus is provided. The
substrate processing apparatus includes: a processing chamber for
performing a processing of forming a thin film on a substrate; a
processing gas supply system for supplying a processing gas to an
inside of the processing chamber; a cleaning gas supply system for
supplying a cleaning gas to the inside of the processing chamber; a
heater for heating the inside of the processing chamber; and a
controller for controlling the heater, the processing gas supply
system, and the cleaning gas supply system, so as to, when
performing the processing on the substrate in the processing
chamber, perform the processing of forming a thin film on the
substrate by supplying a processing gas to the inside of the
processing chamber while heating the inside of the processing
chamber to a processing temperature; and so as to, when cleaning
the inside of the processing chamber, in a state where the
substrate is not present in the processing chamber, remove the thin
film deposited on the inside of the processing chamber by supplying
a fluorine gas solely or a fluorine gas diluted by an inert gas
solely, as the cleaning gas, to the inside of the processing
chamber while heating the inside of the processing chamber to a
first temperature, and subsequently remove an adhered material
remaining on the inside of the processing chamber after removing
the thin film by supplying a fluorine gas solely or a fluorine gas
diluted by an inert gas solely, as the cleaning gas, to the inside
of the processing chamber while heating the inside of the
processing chamber to a second temperature.
[0174] According to a still another aspect of the present
invention, a method for manufacturing a semiconductor device is
provided. The method includes the steps of: loading a substrate
into a processing chamber; performing a processing of forming a
thin film on the substrate by supplying a processing gas to an
inside of the processing chamber; unloading the processed substrate
out of the processing chamber; purging the inside of the processing
chamber with gas while applying a thermal impact onto the thin film
deposited on the inside of the processing chamber by decreasing the
temperature in the processing chamber, so as to forcibly generate a
crack in the thin film and forcibly peel the adhered material with
a weak adhesive force, in a state where the substrate is not
present in the processing chamber; and cleaning the inside of the
processing chamber by supplying a cleaning gas to the inside of the
processing chamber. The step of cleaning the inside of the
processing chamber includes the steps of: removing the thin film
deposited on the inside of the processing chamber by supplying a
fluorine-based gas, as the cleaning gas, to the inside of the
processing chamber heated to a first temperature, and removing an
adhered material remaining on the inside of the processing chamber
after removing the thin film by supplying a fluorine-based gas, as
the cleaning gas, to the inside of the processing chamber heated to
a second temperature.
[0175] According to a still another aspect of the present
invention, a method for manufacturing a semiconductor device is
provided. The method includes the steps of: loading a substrate
into a processing chamber; performing a processing of forming a
thin film on the substrate by supplying a processing gas to an
inside of the processing chamber; unloading the processed substrate
out of the processing chamber; purging the inside of the processing
chamber with gas while applying a thermal impact onto the thin film
deposited on the inside of the processing chamber by decreasing the
temperature in the processing chamber, so as to forcibly generate a
crack in the thin film and forcibly peel the adhered material with
a weak adhesive force, in the state where the substrate is not
present in the processing chamber; and cleaning the inside of the
processing chamber by supplying a cleaning gas to the inside of the
processing chamber. The step of cleaning the inside of the
processing chamber includes the steps of: removing the thin film
deposited on the inside of the processing chamber by supplying a
fluorine gas solely or a fluorine gas diluted by an inert gas
solely, as the cleaning gas, to the inside of the processing
chamber heated to a first temperature; and removing an adhered
material remaining on the inside of the processing chamber after
removing the thin film by supplying a fluorine gas solely or a
fluorine gas diluted by an inert gas solely, as the cleaning gas,
to the inside of the processing chamber heated to a second
temperature.
[0176] It is preferable that the step of purging the inside of the
processing with gas chamber should forced-cool the inside of the
processing chamber by causing a cooling medium to flow outside of
the processing chamber.
[0177] It is preferable that the step of purging the inside of the
processing chamber with gas should forced-cool the inside of the
processing chamber by causing a cooling medium to flow outside the
processing chamber, while exhausting a high-temperature atmospheric
gas outside the processing chamber.
[0178] According to another aspect of the present invention, a
substrate processing apparatus is provided. The apparatus includes:
a processing chamber for performing a processing of forming a thin
film on a substrate; a processing gas supply system for supplying a
processing gas for forming the thin film to the inside of the
processing chamber; a purge-gas supply system for supplying a purge
gas to the inside of the processing chamber; a cleaning gas supply
system for supplying a cleaning gas for cleaning the inside of the
processing chamber to the inside of the processing chamber, an
exhaust system for exhausting the inside of the processing chamber;
a heater for heating the inside of the processing chamber;
and a controller which controls the heater, the purge-gas supply
system and the exhaust system so as to purge the inside of the
processing chamber with gas while applying a thermal impact onto
the thin film deposited on the inside of the processing chamber by
decreasing the temperature in the processing chamber, so as to
forcibly generate a crack in the thin film and forcibly peel the
adhered material with a weak adhesive force, in a state where the
substrate is not present in the processing chamber; and which
controls the heater, the cleaning gas supply system, and the
exhaust system, so as to, when cleaning the inside of the
processing chamber, remove the thin film deposited on the inside of
the processing chamber by supplying a fluorine gas solely or a
fluorine gas diluted by an inert gas solely, as the cleaning gas,
to the inside of the processing chamber while heating the inside of
the processing chamber to a first temperature, and subsequently,
remove the adhered material remaining on the inside of the
processing chamber after removing the thin film by supplying a
fluorine gas solely or a fluorine gas diluted by an inert gas
solely, as the cleaning gas, to the inside of the processing
chamber while heating the inside of the processing chamber to a
second temperature.
[0179] According to a still another aspect of the present
invention, a substrate processing apparatus is provided. The
apparatus includes: a processing chamber for performing a
processing of forming a thin film on a substrate; a processing gas
supply system for supplying a processing gas for forming the thin
film to the inside of the processing chamber; a purge-gas supply
system for supplying a purge gas to the inside of the processing
chamber; a cleaning gas supply system for supplying a cleaning gas
for cleaning the inside of the processing chamber to the inside of
the processing chamber, an exhaust system for evacuating the inside
of the processing chamber; a heater for heating the inside of the
processing chamber; a forced-cooling mechanism which is provided at
the outside of the processing chamber so as to cover the processing
chamber for forced-cooling the inside of the processing chamber;
and a controller which controls the forced-cooling mechanism, the
heater, the purge-gas supply system, and the exhaust system, so as
to purge the inside of the processing chamber with gas by applying
a thermal impact onto the thin film deposited on the inside of the
processing chamber by decreasing the temperature in the processing
chamber by means of forced-cooling of the inside of the processing
chamber, so as to forcibly generate a crack in the thin film and
forcibly peel the adhered material with a weak adhesive force, in
the state where the substrate is not present in the processing
chamber, and which controls the heater, the cleaning gas supply
system, and the exhaust system, so as to, when cleaning the inside
of the processing chamber, remove the thin film deposited on the
inside of the processing chamber by supplying a fluorine gas solely
or a fluorine gas diluted by an inert gas solely, as the cleaning
gas, to the inside of the processing chamber while heating the
inside of the processing chamber to a first temperature, and
subsequently, remove the adhered material remaining on the inside
of the processing chamber after removing the thin film by supplying
a fluorine gas solely or a fluorine gas diluted by an inert gas
solely, as the cleaning gas, to the inside of the processing
chamber while heating the inside of the processing chamber to a
second temperature.
[0180] According to a still another aspect of the present
invention, a substrate processing apparatus is provided. The
apparatus includes: a processing chamber for performing a
processing of forming a thin film on a substrate; a processing gas
supply system for supplying a processing gas for forming the thin
film to the inside of the processing chamber; a purge-gas supply
system for supplying a purge gas to the inside of the processing
chamber; a cleaning gas supply system for supplying a cleaning gas
for cleaning the inside of the processing chamber to the inside of
the processing chamber, an exhaust system for evacuating the inside
of the processing chamber; a heater for heating the inside of the
processing chamber; a forced-cooling mechanism which is provided
outside of the processing chamber so as to cover the processing
chamber for forced-cooling the inside of the processing chamber;
and a controller which controls the forced-cooling mechanism, the
heater, the purge-gas supply system and the exhaust system, so as
to purge the inside of the processing chamber with gas while
applying a thermal impact onto the thin film deposited on the
inside of the processing chamber, by decreasing the temperature in
the processing chamber by means of forced-cooling of the inside of
the processing chamber, so as to forcibly generate a crack in the
thin film and forcibly peel the adhered material with a weak
adhesive force, in a state where the substrate is not present in
the processing chamber and which controls the heater, the cleaning
gas supply system, and the exhaust system, so as to, when cleaning
the inside of the processing chamber, remove the thin film
deposited on the inside of the processing chamber by supplying a
fluorine-based gas, as the cleaning gas, to the inside of the
processing chamber while heating the inside of the processing
chamber to a first temperature, and subsequently remove the adhered
material remaining on the inside of the processing chamber after
removing the thin film, by supplying a fluorine-based gas to the
inside of the processing chamber, as the cleaning gas, while
heating the inside of the processing chamber to a second
temperature.
* * * * *