U.S. patent application number 12/406750 was filed with the patent office on 2009-07-16 for method of producing semiconductor device.
This patent application is currently assigned to Hitachi Kokusai Electric Inc.. Invention is credited to Norikazu Mizuno, Kazuyuki Okuda.
Application Number | 20090181547 12/406750 |
Document ID | / |
Family ID | 38541264 |
Filed Date | 2009-07-16 |
United States Patent
Application |
20090181547 |
Kind Code |
A1 |
Okuda; Kazuyuki ; et
al. |
July 16, 2009 |
METHOD OF PRODUCING SEMICONDUCTOR DEVICE
Abstract
Disclosed is a substrate processing apparatus, including: a
processing space to provide a space in which a substrate is to be
processed; a heating member to heat the processing space; a gas
supply member to supply at least first and second processing gases
to the processing space; an exhaust member to exhaust an atmosphere
in the processing space; and a control member to control at least
the gas supply member and the exhaust member such that supply and
exhaust of the first and second processing gases are alternately
repeated a plurality of times so that the first and second
processing gases are not mixed with each other in the processing
space when forming a desired film on the substrate, and both the
first and second processing gases are supplied to the processing
space when coating a surface of an inner wall of the processing
space with a desired film.
Inventors: |
Okuda; Kazuyuki;
(Toyama-shi, JP) ; Mizuno; Norikazu; (Toyama-shi,
JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
Hitachi Kokusai Electric
Inc.
|
Family ID: |
38541264 |
Appl. No.: |
12/406750 |
Filed: |
March 18, 2009 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11990445 |
Dec 12, 2008 |
|
|
|
PCT/JP2007/056609 |
Mar 28, 2007 |
|
|
|
12406750 |
|
|
|
|
Current U.S.
Class: |
438/758 ;
257/E21.211 |
Current CPC
Class: |
H01L 21/3185 20130101;
C23C 16/45546 20130101; H01L 21/67109 20130101; C23C 16/45578
20130101; Y10S 427/106 20130101; H01L 21/3141 20130101; C23C
16/45538 20130101 |
Class at
Publication: |
438/758 ;
257/E21.211 |
International
Class: |
H01L 21/30 20060101
H01L021/30 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2006 |
JP |
2006-088192 |
Claims
1. A method of producing a semiconductor device, comprising:
coating a surface of an inner wall of a processing space and a
buffer space with a coating film, the processing space being
defined by a reaction tube in which a substrate is to be processed,
and the buffer space is provided at an inner wall of the reaction
tube and partitioned from the processing space, by heating the
processing space to a first temperature, and supplying a first
processing gas and a second processing gas to the processing space
without activating by a plasma excitation, the first processing gas
being supplied to the processing space through the buffer space to
form the coating film on the surface of the inner wall of the
processing space and the buffer space; and forming a thin film on
the substrate by placing the substrate in the processing space,
heating the processing space to a second temperature lower than the
first temperature, exposing the substrate to the first processing
gas activated by a plasma excitation, removing the first processing
gas from the processing space, exposing the substrate to the second
processing gas, removing the second processing gas from the
processing space, and alternately repeating the steps of exposing
the substrate to the first processing gas and exposing the second
processing gas a plurality of times to form the thin film on the
substrate.
2. A method of producing a semiconductor device, comprising:
coating a surface of an inner wall of a processing space with a
coating film by supplying at least two different processing gases
to the processing space to form the coating film on the surface of
the inner wall of the processing space; and forming a thin film on
the substrate accommodated in the processing space by repeatedly
performing a predetermined cycle, each predetermined cycle
including applying alternating pulses of different processing gases
so that each processing gases are not mixed with each other in the
processing space, wherein processing gases supplied in the
processing space in the coating step and the forming step are same
gases.
3. The method of producing a semiconductor device as recited in
claim 2, wherein the processing space is defined by a reaction tube
that provides a space in which a substrate is to be processed, an
inner wall of the reaction tube is provided with a buffer space
partitioned from the processing space, at least one of the
processing gases is provided in a buffer space to expose the
substrate, through the buffer space, and the coating film is also
formed on a surface of an inner wall of the buffer space.
4. The method of producing a semiconductor device as recited in
claim 2, wherein at least one of the processing gases is activated
by a plasma excitation when coating the surface of the inner wall
of the processing space with a coating film, and no processing gas
is activated by the plasma excitation when forming the thin film on
the substrate.
5. The method of producing a semiconductor device as recited in
claim 4, wherein the processing space is heated to a first
temperature when coating the surface of the inner wall of the
processing space with a coating film, and the processing space is
heated to a second temperature lower than the first temperature
when forming the thin film on the substrate.
6. A method of producing a semiconductor device, comprising:
forming a thin film on a substrate accommodated in a processing
space by repeatedly performing a predetermined cycle, each
predetermined cycle including, applying alternating pulses of a
first processing gas and a second processing gas so that each
processing gases are not mixed with each other in the processing
space, supplying a cleaning gas in the processing space, and
coating a surface of an inner wall of the processing space with a
coating film by supplying the first processing gas and the second
processing gas to the processing space to form the coating film on
the surface of the inner wall of the processing space, wherein the
steps of forming the thin film, supplying a cleaning gas, and
coating the surface of the inner wall of the processing space are
sequentially performed.
Description
[0001] This application is a Divisional of co-pending application
Ser. No. 11/990,445 filed on Feb. 14, 2008, and for which priority
is claimed under 35 U.S.C. .sctn. 120. application Ser. No.
11/990,445 is the national phase of PCT International Application
No. PCT/JP2007/056609 filed on Mar. 28, 2007 under 35 U.S.C. .sctn.
371. The entire contents of each of the above-identified
applications are hereby incorporated by reference. This application
also claims priority of Application No. 2006-088192 filed in Japan
on Mar. 28, 2006 under 35 U.S.C. .sctn. 119.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a substrate processing
apparatus, and more particularly, to a film forming apparatus used
when producing a semiconductor device such as a Si device.
[0004] 2. Description of the Related Art
[0005] In a conventional semiconductor device producing apparatus
which forms a film by an ALD (Atomic Layer Deposition) method, a
coating operation after maintenance such as NF.sub.3 cleaning is
carried out by film forming operation by the ALD method itself (see
Patent Literature 1).
[Patent Literature 1] International Publication No. WO 2004/044970
Pamphlet
[0006] A standard RF power for forming a film on a wafer when
NH.sub.3 plasma is generated is 300 W.
[0007] In this state, however, there is a problem that wafer
contamination caused by Na is a high value exceeding
1.times.10.sup.11 atoms/cm.sup.2.
SUMMARY OF THE INVENTION
[0008] It is a main object of the present invention to provide a
substrate processing apparatus which forms a film by an ALD method
and which can reduce contamination of a substrate by Na.
[0009] According to one aspect of the present invention, there is
provided a substrate processing apparatus, comprising: a processing
space, defined by a reaction tube made of quartz, to provide a
space in which a substrate is to be processed;
[0010] a buffer space provided at an inner wall of the reaction
tube and partitioned from the processing space;
[0011] an electrode provided inside the buffer space, the electrode
being used when a first processing gas is plasma-excited, and high
frequency voltage being to be applied to the electrode;
[0012] a heating member to heat the processing space;
[0013] a gas supply member to supply at least the first processing
gas and a second processing gas to the processing space;
[0014] an exhaust member to exhaust an atmosphere in the processing
space; and
[0015] a control member to control at least the electrode, the
heating member, the gas supply member and the exhaust member such
that plasma is generated and the processing space is heated to a
first temperature and supply and exhaust of the first processing
gas and supply and exhaust of the second processing gas are
alternately repeated a plurality of times so that the first and
second processing gases are not mixed with each other in the
processing space when forming a desired film on the substrate, and
the processing space is heated to a second temperature that is
higher than the first temperature without generating plasma and
both the first and second processing gases are supplied to the
processing space when coating a surface of an inner wall of the
processing space with a desired film, wherein
[0016] the first processing gas is to be supplied to the processing
space through the buffer space, and
[0017] the coating film is also to be formed on a surface of an
inner wall of the buffer space.
[0018] According to another aspect of the present invention, there
is provided a substrate processing apparatus, comprising:
[0019] a processing space to provide a space in which a substrate
is to be processed;
[0020] a heating member to heat the processing space;
[0021] a gas supply member to supply at least first and second
processing gases to the processing space;
[0022] an exhaust member to exhaust an atmosphere in the processing
space; and
[0023] a control member to control at least the gas supply member
and the exhaust member such that supply and exhaust of the first
and second processing gases are alternately repeated a plurality of
times so that the first and second processing gases are not mixed
with each other in the processing space when forming a desired film
on the substrate, and both the first and second processing gases
are supplied to the processing space when coating a surface of an
inner wall of the processing space with a desired film.
[0024] According to another aspect of the present invention, there
is provided a substrate processing apparatus, comprising:
[0025] a processing space to provide a space in which a substrate
is to be processed;
[0026] a heating section to heat the processing space;
[0027] a first gas supply section to supply a first processing gas
to the processing space;
[0028] a second gas supply section to supply a second processing
gas to the processing space;
[0029] an exhaust section to exhaust an atmosphere in the
processing space; and
[0030] a control section to control at least the heating section,
the first and second gas supply sections, and the exhaust section,
such that when the first or second processing gas is supplied from
one of the first and second gas supply sections, an inert gas is
supplied from the other gas supply section so that the first and
second processing gases are not supplied together to the processing
space when the substrate is accommodated in the processing space,
and
[0031] the control section controls such that both the first and
second processing gases are supplied to the processing space from
the first gas supply section and second gas supply section
respectively when the substrate is not accommodated in the
processing space.
BRIEF DESCRIPTION OF DRAWINGS
[0032] FIG. 1 is a schematic diagram showing a structure of a
vertical type substrate processing furnace according to preferred
embodiments of the present invention, and shows a vertical cross
sectional view of a processing furnace portion;
[0033] FIG. 2 is a schematic diagram showing the structure of the
vertical type substrate processing furnace according to the
preferred embodiments of the present invention, and shows a
transverse sectional view of the processing furnace portion;
[0034] FIG. 3 is a diagram for explaining an effect of coating by
an ALD method and an effect of coating by an LP-CVD method;
[0035] FIG. 4 is a diagram for explaining an effect of coating by
the ALD method and an effect of coating by the LP-CVD method;
[0036] FIG. 5 is a diagram for explaining ability to prevent Na
diffusion in the coating by the LP-CVD method;
[0037] FIG. 6A is a schematic transverse sectional view for
explaining a quartz structure of the vertical type substrate
processing furnace according to the preferred embodiments of the
present invention;
[0038] FIG. 6B is a schematic transverse sectional view for
explaining a coating state by the LP-CVD method;
[0039] FIG. 6C is a schematic transverse sectional view for
explaining a coating state by the ALD method; and
[0040] FIG. 7 is a schematic perspective view for explaining a
substrate processing apparatus used for the preferred embodiments
of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0041] Next, preferred embodiments of the present invention will be
explained.
[0042] First, a substrate processing furnace suitably used in the
preferred embodiments of the present invention will be
explained.
[0043] FIG. 1 is a schematic diagram showing a structure of a
vertical type substrate processing furnace preferably used in the
present embodiments, and shows a processing furnace 202 in vertical
section. FIG. 2 is a schematic diagram showing a structure of the
vertical type substrate processing furnace preferably used in the
present embodiments, and shows the processing furnace 202 in
transverse section.
[0044] A substrate processing apparatus used in the present
embodiments includes a controller 208 which is a control section.
The controller 208 controls operation of various parts which
constitute the substrate processing apparatus and the substrate
processing furnace.
[0045] A reaction tube 203 as a reaction container which processes
the wafers 200 as substrates is provided inside a heater 207 which
is a heating device (heating means). A lower end opening of the
reaction tube 203 is air-tightly closed by a seal cap 219 as a lid
through an O-ring 220 which is an air-tight member. A processing
chamber 201 is formed by at least the reaction tube 203 and the
seal cap 219. A boat 217 which is a substrate holding member
(substrate holding means) stands on the seal cap 219 through a boat
support stage 218. The boat support stage is a holding body which
holds the boat 217. The boat 217 is inserted into the processing
chamber 201. A plurality of wafers 200 which are to be subjected to
batch process are stacked on the boat 217 in a horizontal attitude
in multi-layers in the axial direction of the tube. The heater 207
heats the wafers 200 inserted into the processing chamber 201 to a
predetermined temperature.
[0046] Two gas supply tubes 232a and 232b as supply paths are
provided for supplying a plurality of kinds of (here, two kinds of)
gases to the processing chamber 201. A reaction gas is supplied to
the processing chamber 201 from the first gas supply tube 232a
through a first mass flow controller 241a which is a flow rate
control device (flow rate control means) and a first valve 243a
which is an on-off valve, and through a later-described buffer
chamber 237 formed in the reaction tube 203. A gas supply tube 300
is connected to the first gas supply tube 232a on a downstream side
of the first valve 243a. The gas supply tube 300 is provided with a
mass flow controller 310 which is a flow rate control device (flow
rate control means) and a valve 320 which is an on-off valve. An
inert gas such as N.sub.2 is supplied to the processing chamber 201
from the gas supply tube 300 through the mass flow controller 310
and the valve 320, and through the later-described buffer chamber
237 formed in the reaction tube 203.
[0047] A reaction gas is supplied to the processing chamber 201
from the second gas supply tube 232b through a second mass flow
controller 241b which is a flow rate control device (flow rate
control means), a second valve 243b which is an on-off valve, a gas
tank 247, a third valve 243c which is an on-off valve and a
later-described gas supply section 249. A gas supply tube 400 is
connected to the second gas supply tube 232b on a downstream side
of the third valve 243c, and the gas supply tube 400 is provided
with a mass flow controller 410 which is a flow rate control device
(flow rate control means) and a valve 420 which is an on-off valve.
An inert gas such as N.sub.2 is supplied into the processing
chamber 201 from the gas supply tube 400 through the mass flow
controller 410, the valve 420 and the later-described gas supply
section 249.
[0048] The processing chamber 201 is connected to a vacuum pump 246
which is an exhaust device (exhaust means) through a gas exhaust
tube 231 for exhausting gas and a fourth valve 243d so that the
processing chamber 201 can be evacuated. The fourth valve 243d is
an on-off valve capable of evacuating the processing chamber 201
and stopping the evacuation by opening and closing the fourth valve
243d, and capable of adjusting the pressure in the processing
chamber 201 by adjusting valve opening.
[0049] The buffer chamber 237 which is a gas diffusion space is
provided in an arc space between the wafers 200 and an inner wall
of the reaction tube 203 constituting the processing chamber 201
along a stacking direction of the wafers 200 at the inner wall of
the reaction tube 203 from its lower portion to its upper portion.
An end of the wall of the buffer chamber 237 adjacent to the wafers
200 is formed with first gas supply holes 248a which are supply
holes for supplying gas. The first gas supply holes 248a are opened
toward the center of the reaction tube 203. The first gas supply
holes 248a have the same opening areas from the lower portion to
the upper portion, and they have the same opening pitches.
[0050] A nozzle 233 is disposed on an end of the buffer chamber 237
opposite from the end where the first gas supply holes 248a are
provided along the stacking direction of the wafers 200 from a
lower portion to an upper portion of the reaction tube 203. The
nozzle 233 is provided with second gas supply holes 248b which are
supply holes for supplying a plurality of gases. When a pressure
difference between the buffer chamber 237 and the processing
chamber 201 is small, opening areas of the second gas supply holes
248b may be the same and the opening pitches may also be the same
from upstream side to downstream side of gas, but when the pressure
difference is great, the opening areas should be increased or the
opening pitches should be reduced from the upstream side toward the
downstream side.
[0051] In the present embodiments, the opening areas of the second
gas supply holes 248b are gradually increased from the upstream
side toward the downstream side. With this structure, gases having
different flow velocities but having substantially the same flow
rates flow into the buffer chamber 237 from the second gas supply
holes 248b.
[0052] After the differences between particle velocities of gases
blown out from the respective second gas supply holes 248b are
moderated in the buffer chamber 237, the gases blow out from the
first gas supply holes 248a into the processing chamber 201.
Therefore, when the gases blown out from the respective second gas
supply holes 248b blow out from the respective first gas supply
holes 248a, the gases have equal flow rates and flow
velocities.
[0053] A first rod-like electrode 269 which is a first electrode
having a thin and long structure, and a second rod-like electrode
270 which is a second electrode are disposed in the buffer chamber
237 such that the electrodes are protected from their upper
portions to lower portions by electrode protecting pipes 275 which
are protecting pipes for protecting the electrodes. One of the
first rod-like electrode 269 and the second rod-like electrode 270
is connected to a high frequency power supply 273 through a
matching device 272, and the other one is connected to the ground
which is a reference potential. As a result, plasma is generated in
a plasma generating region 224 between the first rod-like electrode
269 and the second rod-like electrode 270.
[0054] The electrode protecting pipes 275 can be inserted into the
buffer chamber 237 in a state where the first rod-like electrode
269 and the second rod-like electrode 270 are isolated from an
atmosphere in the buffer chamber 237. If the atmosphere in the
electrode protecting pipes 275 is the same as outside air
(atmosphere), the first rod-like electrode 269 and the second
rod-like electrode 270 inserted into the electrode protecting pipes
275 are oxidized by heat of a heater 207. An inert gas purge
mechanism is provided for charging or purging an inert gas such as
nitrogen into or from the electrode protecting pipes 275,
suppressing oxygen density to a sufficient low level, and
preventing the first rod-like electrode 269 or the second rod-like
electrode 270 from being oxidized.
[0055] The gas supply section 249 is provided at an inner wall of
the reaction tube 203 away from a position of the first gas supply
holes 248a by about 120.degree. along an inner periphery of the
reaction tube 203. The gas supply section 249 is a supply section
for sharing gas supply kinds with the buffer chamber 237 when
supplying a plurality of kinds of gases alternately to the wafers
200 one kind by one kind in film formation by the ALD method.
[0056] The gas supply section 249 also includes third gas supply
holes 248c like the buffer chamber 237 at locations adjacent to the
wafers. The third gas supply holes 248c are supply holes for
supplying gas at the same pitches. The second gas supply tube 232b
is connected to a lower portion of the gas supply section 249.
[0057] When a pressure difference between the gas supply section
249 and the processing chamber 201 is small, opening areas of the
third gas supply holes 248c may be the same and the opening pitches
may be also the same from upstream side to downstream side of gas,
but when the pressure difference is great, the opening areas should
be increased or the opening pitches should be reduced from the
upstream side toward the downstream side.
[0058] In the present embodiments, the opening areas of the third
gas supply holes 248c are gradually increased from the upstream
side toward the downstream side.
[0059] A boat 217 is provided at a central portion in the reaction
tube 203. The plurality of wafers 200 are to be placed on the boat
217 in multi-layers at an equal distance from each other. The boat
217 can be loaded into and unloaded from the reaction tube 203 by a
boat elevator mechanism (not shown). Further, to enhance the
uniformity of the processing, there is provided a boat rotating
mechanism 267 which is a rotating device (rotating means) for
rotating the boat 217. By rotating the boat rotating mechanism 267,
the boat 217 held by a quartz cap 218 is rotated.
[0060] A controller 280 which is control means is connected to the
first and second mass flow controllers 241a and 241b, the mass flow
controllers 310 and 410, the first to fourth valves 243a, 243b,
243c and 243d, the valves 320 and 420, the heater 207, the vacuum
pump 246, the boat rotating mechanism 267, the boat elevator
mechanism (not shown), the high frequency power supply 273 and the
matching device 272. The controller 280 controls the adjustment of
flow rates of the first and second mass flow controllers 241a and
241b and the mass flow controllers 310 and 410, controls opening
and closing of the first to third valves 243a, 243b and 243c and
the valves 320 and 420, controls opening and closing and the
pressure adjustment of the fourth valve 243d, controls temperature
adjustment of the heater 207, controls actuation and stop of the
vacuum pump 246, controls adjustment of rotation speed of the boat
rotating mechanism 267, controls the vertical movement of the boat
elevator mechanism, controls electricity supply of the high
frequency power supply 273, and controls impedance by the matching
device 272.
[0061] Next, a film forming example using the ALD method will be
explained giving an example of forming a SiN film using DCS and
NH.sub.3 gases as one of producing methods of a semiconductor
device.
[0062] The ALD (Atomic Layer Deposition) method which is one of CVD
(Chemical Vapor Deposition) methods is a technique in which two (or
more) kinds of material gases used for forming films are
alternately supplied onto substrates one by one under a given film
forming condition (temperature, time and the like), the gases are
adsorbed on an atom-layer basis, and films are formed utilizing
surface reaction.
[0063] When a SiN (silicon nitride) film is to be formed for
example, according to the ALD method, it is possible to form a high
quality film at a low temperature in a range of 300 to 600.degree.
C. using DCS (SiH.sub.2Cl.sub.2, dichlorsilane) and NH.sub.3
(ammonia) as chemical reaction to be utilized. A plurality of kinds
of reaction gases are alternately supplied one by one. The film
thickness is controlled based on the number of cycles of the supply
of reaction gas. (When a film forming speed is 1 .ANG./cycle, in
order to form a film of 20 .ANG., the film forming processing is
carried out by 20 cycles.)
[0064] First, the boat 217 is charged with wafers 200 on which
films are to be formed, and the boat 217 is loaded into the
processing chamber 201. After the loading, the following three
steps are executed sequentially.
[0065] (Step 1)
[0066] In step 1, NH.sub.3 gas which needs plasma excitation and
DCS gas which does not need plasma excitation flow in parallel.
First, the first valve 243a provided in the first gas supply tube
232a and the fourth valve 243d provided in the gas exhaust tube 231
are both opened, NH.sub.3 gas whose flow rate is adjusted by the
first mass flow controller 243a from the first gas supply tube 232a
blows into the buffer chamber 237 from the second gas supply holes
248b of the nozzle 233, high frequency electricity is applied
between the first rod-like electrode 269 and the second rod-like
electrode 270 from the high frequency power supply 273 through the
matching device 272 to plasma-excite NH.sub.3, the NH.sub.3 is
supplied into the processing chamber 201 as active species, and the
NH.sub.3 is exhausted from the gas exhaust tube 231. When the
NH.sub.3 gas flows by plasma excitation as the active species, the
fourth valve 243d is appropriately adjusted to maintain a pressure
in the processing chamber 201 at a desired pressure within a range
of 10 to 100 Pa. The supply flow rate of NH.sub.3 controlled by the
first mass flow controller 241a is a desired flow rate within a
range of 1 to 10 slm. Time during which the wafers 200 are exposed
to the active species obtained by plasma-exciting NH.sub.3 is
desired time within a range of 2 to 120 seconds. The temperature of
the heater 207 at that time is set to be a desired temperature
within a range of 300 to 600.degree. C. Since a reaction
temperature of NH.sub.3 is high, NH.sub.3 does not react at the
wafer temperature. Therefore, NH.sub.3 flows as active species by
plasma excitation. Thus, the wafer temperature is in the set low
temperature range.
[0067] When NH.sub.3 is plasma-excited and supplied as active
species, the second valve 243b located upstream side of the second
gas supply tube 232b is opened, the third valve 243c located
downstream side is closed and DCS also flows. With this, DCS is
stored in the gas tank 247 provided between the second and third
valves 243b and 243c. At that time, gas flowing into the processing
chamber 201 is active species obtained by plasma-exciting NH.sub.3,
and DCS does not exist. Therefore, NH.sub.3 which is plasma-excited
and becomes active species surface-reacts (chemisorption) with a
surface portion such as a foundation film on the wafer 200 without
causing vapor-phase reaction. In step 1, while NH.sub.3 is
plasma-excited and supplied as active species, the valve 420 is
opened to supply an inert gas such as N.sub.2 into the processing
chamber 201 from the gas supply tube 400 so that NH.sub.3 does not
enter the gas supply section 249.
[0068] (Step 2)
[0069] In step 2, the first valve 243a of the first gas supply tube
232a and the valve 420 of the gas supply tube 400 are closed, the
supply of NH.sub.3 and the supply of inert gas are stopped, but
supply to the gas tank 247 is continued. If a predetermined amount
of DCS at a predetermined pressure is stored in the gas tank 247,
the upstream second valve 243b is also closed to trap DCS in the
gas tank 247. The fourth valve 243d of the gas exhaust tube 231 is
left open, the gas in the processing chamber 201 is exhausted to 20
Pa or less by the vacuum pump 246, and remaining NH.sub.3 is
exhausted from the processing chamber 201. At that time, if the
valve 420 and the valve 320 are opened and closed to repeat supply
and supply-stop of an inert gas such as N.sub.2 into the processing
chamber 201 from the gas supply tube 400 and the gas supply tube
300, the effect for eliminating remaining NH.sub.3 is enhanced. DCS
is stored in the gas tank 247 such that the pressure therein
becomes 20000 Pa or higher. Further, the apparatus is constituted
such that a conductance between the gas tank 247 and the processing
chamber 201 becomes 1.5.times.10.sup.-3 m.sup.3/s or higher. It is
preferable that a capacity of the gas tank 247 is in a range of 100
to 300 cc if a capacity of the reaction tube 203 is 100 l (liters)
when considering a ratio of a required capacity of the gas tank 247
to a capacity of the reaction tube 203, and the capacity ratio of
the gas tank 247 is 1/1000 to 3/1000 times of the reaction chamber
capacity.
[0070] (Step 3)
[0071] In step 3, after exhausting in the processing chamber 201,
the fourth valve 243d of the gas exhaust tube 231 is closed to stop
exhausting. The third valve 243c which is a downstream side of the
second gas supply tube 232b is opened. With this, DCS stored in the
gas tank 247 is supplied into the processing chamber 201 at a dash.
At that time, since the fourth valve 243d of the gas exhaust tube
231 is closed, the pressure in the processing chamber 201 abruptly
increases and reaches to about 931 Pa (7 Torr). Time during which
DCS is supplied is set to two to four seconds, and time during
which the wafers are exposed to the increased pressure atmosphere
thereafter is set to two to four seconds, and the total time is set
to six seconds. The wafer temperature at that time is maintained at
a desired temperature within a range of 300 to 600.degree. C. like
the case when NH.sub.3 is supplied. By supplying DCS, DCS and
NH.sub.3 which are chemisorbed on a surface of the wafer 200
surface-react (chemisorption) with each other, and a SiN film is
formed on a wafer 200. In step 3, while DCS is supplied into the
processing chamber 201, the valve 320 is opened to supply an inert
gas such as N.sub.2 into the processing chamber 201 from the gas
supply tube 300 so that DCS does not enter the buffer chamber 237.
After the film formation, the third valve 243c and the valve 320
are closed, the fourth valve 243d is opened to evacuate the
processing chamber 201, and remaining DCS gas after contributing to
the film formation is eliminated. At that time, if the valve 420
and the valve 320 are opened and closed to repeat supply of an
inert gas such as N.sub.2 into the processing chamber 201 from the
gas supply tube 400 and the gas supply tube 300 and stop of the
supply, the effect for eliminating, from the processing chamber
201, the remaining DCS gas after contributing to the film formation
is further enhanced. The second valve 243b is opened to start the
supply of DCS to the gas tank 247.
[0072] The above steps 1 to 3 are defined as one cycle. By
repeating this cycle a plurality of times, a SiN film having
predetermined thickness is formed on the wafer.
[0073] In the ALD apparatus, gas is chemisorbed on a surface
portion of the wafer 200. The absorption amount of gas is
proportional to gas pressure and gas exposing time. Therefore, in
order to absorb a desired given amount of gas within a short time,
it is necessary to increase the pressure of gas within a short
time. In this embodiment, since the fourth valve 243d is closed and
DCS stored in the gas tank 247 is instantaneously supplied, it is
possible to abruptly increase the pressure of DCS in the processing
chamber 201, and to absorb a desired constant amount of gas
instantaneously.
[0074] In this embodiment, while DCS is stored in the gas tank 247,
NH.sub.3 gas is plasma-excited and supplied as active species and
exhausted from the processing chamber 201. This step is necessary
in the ALD method. Therefore, a special step for storing DCS is not
required. Further, since DCS flows after exhausting in the
processing chamber 201 to remove NH.sub.3 gas, NH.sub.3 gas and DCS
do not react with each other on the way to the wafers 200. The
supplied DCS can react effectively only with NH.sub.3 absorbed in
the wafers 200.
[0075] In this embodiment, the reaction tube 203, the buffer
chamber 237 and the gas supply section 249 used in the substrate
processing apparatus shown in FIGS. 1 and 2 are made of quartz.
[0076] As described above, SiN (silicon nitride) films are formed
on wafers 200 by the ALD method. When coating a quartz member such
as the reaction tube 203 by the ALD method, the coating is carried
out under the condition that the wafers 200 are not placed on the
boat 217, but gas is supplied as in the case of forming SiN
(silicon nitride) films on the wafers 200.
[0077] When coating a quartz member such as the reaction tube 203
by the CVD method, NH.sub.3 is supplied from the buffer chamber 237
and DCS gas is supplied from the gas supply section 249 at the same
time (see FIG. 6B). The coating is carried out under the condition
that the wafers 200 are not placed on the boat 217.
[0078] The coating is carried out when a quartz member such as the
reaction tube 203 is replaced or after cleaning processing using
gas such as NF.sub.3 is carried out. When the cleaning is carried
out, cleaning gas such as NF.sub.3 is supplied from the gas supply
section 249 and an inert gas such as N.sub.2 is supplied from the
buffer chamber 237 at the same time. The inert gas is supplied from
the buffer chamber 237 to prevent the cleaning gas from flowing
into the buffer chamber 237. After the cleaning processing is
executed, the coating is carried out for a quartz member such as
the reaction tube 203 by the ALD method or the CVD method or by a
combination thereof and then, the SiN film is formed by the ALD
method.
[0079] In this embodiment, in the substrate processing apparatus
which forms the SiN film by the ALD method, the following
pretreatment and film forming condition are changed as follows:
[0080] (1) A surface of a quartz member such as the reaction tube
203 is coated by an LP-CVD (Low Pressure Chemical Vapor Deposition)
method.
[0081] (2) When NH.sub.3 plasma is generated at the time of ALD
film forming processing, RF power is set to 100 or less, more
preferably to 50 W or less.
[0082] With this, contamination of a wafer by Na could be reduced
to about 5.times.10.sup.10 atoms/cm.sup.2 or less.
[0083] One example of the coating by the LP-CVD method is as
follows:
[0084] The coating temperature is in a range of 600 to 760.degree.
C., the pressure is in a range of 10 to 100 Pa, the flow rate of
NH.sub.3 is in a range of 500 to 3,000 sccm, the flow rate of DCS
is in a range of 50 to 300 sccm, and time is in a range of 1 to 3
hours. These values are set to and maintained at desired values
within the above-described ranges.
[0085] One example of the ALD film forming is as follows:
[0086] A film forming temperature is in a range of 300 to
600.degree. C. In NH.sub.3 supply step, a pressure is in a range of
10 to 200 Pa, a flow rate of NH.sub.3 is in a range of 1,000 to
10,000 sccm, and time is in a range of 2 to 120 seconds. In DCS
supply step, a pressure is in a range of 700 to 3500 Pa, a flow
rate of DCS is in a range of 500 to 2,000 sccm, and time is in a
range of 1 to 20 seconds. These values are set to and maintained at
desired values within the above-described ranges.
[0087] The Na contamination did not die down even if the apparatus
and the quartz member were used for a long term. Therefore, it was
contemplated that the cause of the Na contamination exists outside
of a quartz member such as the reaction tube 203. Hence, the
surface coating effect by the LP-CVD method was checked. As a
result, there was obtained data from which it could be expected
that Na contamination was slightly reduced by the coating by the
LP-CVD method. The contamination reduction effect by the coating by
the ALD method is small (see FIG. 3).
[0088] Thereafter, to obtain further improvement effect, various
experiments and verifications were carried out. As a result, there
was obtained data from which it could be expected that Na
contamination could be reduced by reducing the RF power when
forming films by the ALD method (see RF50W(1) in FIG. 4).
[0089] However, verification was again carried out after cleaning
using NF.sub.3, it was found that the Na contamination amount was
not reduced only by reducing the RF power when forming films by the
ALD method (see RF50W(2) in FIG. 4).
[0090] The data was analyzed in detail, and it was found that the
Na contamination amount was reduced under the condition that the
pretreatment by the coating of the LP-CVD method was carried out
and RF power was reduced when forming films by the ALD method. As a
result of retrial, it was confirmed that the combination of these
two operations was effective (see RF50W(3) in FIG. 4).
[0091] As a result, if mechanism of mixing of Na contamination and
mechanism for preventing the mixing by the above method are
estimated, it can be contemplated as follows:
[0092] (1) Na is easily diffused into a quartz member, and Na is
diffused and mixed from outside of the quartz member.
[0093] (2) Na in a coating film or the like exists in a form of ion
or in a form similar to ion. It is contemplated that Na diffusion
is facilitated by electric effect. Therefore, if RF power is
reduced, Na diffusion can be reduced.
[0094] (3) Since plasma is used in the coating processing by the
ALD method, Na is attracted, and Na is prone to be taken into a
film itself during film formation. It is contemplated that Na which
is once taken into a film produces diffusion Path. On the other
hand, since the coating processing by the LP-CVD method does not
use plasma, Na is not attracted, Na is not included in a film
itself and thus, Na diffusion preventing ability is high (see FIG.
5).
[0095] (4) In the coating processing by the ALD method, it is
contemplated that since gas is not mixed, quartz members existing
around the RF electrodes 269 and 270 are not coated (see FIG. 6C).
In the coating processing by LP-CVD method, on the other hand, it
is contemplated that gas mixture of DCS
(SiH.sub.2Cl.sub.2)+NH.sub.3 reaches quartz members around the RF
electrodes 269 and 270, and inside of the buffer chamber 237 is
also coated and thus, the effect is especially enhanced (see FIG.
6B).
[0096] It is contemplated that the above-described action reduces
the Na contamination amount.
[0097] As described above, according to the preferred embodiments
of the present invention, in a semiconductor device producing
apparatus which forms a SiN film by the ALD method, contamination
of wafers by Na can be reduced.
[0098] In the best mode for carrying out the present invention, the
substrate processing apparatus is constituted as a semiconductor
device producing apparatus which carries out the processing steps
in the producing method of a semiconductor device (IC) as one
example. In the following explanation, a case in which a vertical
type apparatus (simply, a processing apparatus, hereinafter) which
subjects a substrate to oxidation processing, diffusion processing,
CVD processing and the like is applied as a substrate processing
apparatus will be described. FIG. 7 is a perspective view of a
processing apparatus to which the present invention is applied.
[0099] As shown in FIG. 7, a processing apparatus 101 of the
present invention uses cassettes 110 as wafer carriers which
accommodate wafers (substrates) 200 made of silicon. The processing
apparatus 101 includes a casing 111 having a front wall 111a. A
front maintenance opening 103 as an opening is formed at a lower
portion of the front wall so that maintenance can be carried out. A
front maintenance door 104 is provided for opening and closing the
front maintenance opening 103. A cassette carry in/out opening (a
substrate container carry in/out opening) 112 is formed at the
maintenance door 104 so that an inside and an outside of the casing
111 are in communication through the cassette carry in/out opening
112. The cassette carry in/out opening 112 is opened and closed by
a front shutter (substrate container carry in/out opening
open/close mechanism) 113. A cassette stage (a substrate container
delivery stage) 114 is disposed at the cassette carry in/out
opening 112 inside the casing 111. The cassette 110 is transferred
onto the cassette stage 114 by a rail guided vehicle (not shown)
and carried out from the cassette stage 114. The cassette 110
delivered by the rail guided vehicle is placed on the cassette
stage 114 such that the wafers 200 in the cassette 110 are in their
vertical attitudes and an opening of the cassette 110 for taking
wafers in and out is directed upward. The cassette stage 114 is
constituted such that it rotates the cassette 110 clockwisely in
the vertical direction by 90.degree. to rearward of the casing, the
wafers 200 in the cassette 110 are in their horizontal attitudes,
and the opening of the cassette 110 for taking wafers in and out is
directed to rearward of the casing.
[0100] Cassette shelves (substrate container placing shelves) 105
are disposed substantially at a central portion in the casing 111
in its longitudinal direction, and the cassette shelves 105 store a
plurality of cassettes 110 in a plurality of rows and a plurality
of lines. The cassette shelves 105 are provided with transfer
shelves 123 in which the cassettes 110 to be transferred by a wafer
loading mechanism 125 are to be accommodated. Auxiliary cassette
shelves 107 are provided above the cassette stage 114 to
subsidiarily store the cassettes 110.
[0101] A cassette transfer device (a substrate container transfer
device) 118 is provided between the cassette stage 114 and the
cassette shelves 105. The cassette transfer device 118 includes a
cassette elevator (a substrate container elevator mechanism) 118a
capable of vertically moving while holding the cassette 110, and a
cassette transfer mechanism (a substrate container transfer
mechanism) 118b as a transfer mechanism. The cassette transfer
device 118 transfers the cassette 110 between the cassette stage
114, the cassette shelves 105 and the auxiliary cassette shelves
107 by a continuous motion of the cassette elevator 118a and the
cassette transfer mechanism 118b.
[0102] A wafer loading mechanism (a substrate transfer mechanism)
125 is provided behind the cassette shelves 105. The wafer loading
mechanism 125 includes a wafer loading device (a substrate loading
device) 125a which can rotate or straightly move the wafer 200 in
the horizontal direction, and a wafer loading device elevator (a
substrate loading device elevator mechanism) 125b which vertically
moves the wafer loading device 125a. The wafer loading device
elevator 125b is provided on a right end of the pressure-proof
casing 111. Tweezers (a substrate holding body) 125c of the wafer
loading device 125a as a placing portion of the wafers 200 charges
a boat (a substrate holding tool) 217 with wafers 200 and
discharges the wafers 200 from the boat 217 by continuous motion of
the wafer loading device elevator 125b and the wafer loading device
125a.
[0103] A processing furnace 202 is provided at a rear and upper
portion in the casing 111. A lower end of the processing furnace
202 is opened and closed by a furnace opening shutter (a furnace
opening open/close mechanism) 147. A boat elevator (a substrate
holding tool elevator mechanism) 115 is provided below the
processing furnace 202 as an elevator mechanism for vertically
moving the boat 217 to and from the processing furnace 202. A seal
cap 219 as a lid is horizontally set up on an arm 128 as a
connecting tool connected to an elevating stage of the boat
elevator 115. The seal cap 219 vertically supports the boat 217,
and can close a lower end of the processing furnace 202.
[0104] The boat 217 includes a plurality of holding members, and
horizontally holds a plurality of wafers 200 (e.g., about 50 to 150
wafers) which are arranged in the vertical direction such that
centers thereof are aligned with each other.
[0105] As shown in FIG. 7, a clean unit 134a is provided above the
cassette shelves 105. The clean unit 134a includes a dustproof
filter and a supply fan for supplying clean air which is a purified
atmosphere so that the clean air flows into the casing 111.
[0106] As typically shown in FIG. 7, a clean unit 134b comprising a
supply fan for supplying clean air and a dustproof filter is
provided on a left side of the casing 111, i.e. on the opposite
side of the wafer loading device elevator 125b and the boat
elevator 115. Clean air belched out from the clean unit 134b flows
through the wafer loading device 125a and the boat 217, and then is
sucked in by an exhaust device (not shown), and is exhausted
outside the casing 111.
[0107] Next, an operation of the substrate processing apparatus
according to the preferred embodiment of the present invention will
be explained.
[0108] As shown in FIG. 7, before the cassette 110 is supplied to
the cassette stage 114, the cassette carry in/out opening 112 is
opened by the front shutter 113. Then, the cassette 110 is
transferred in from the cassette carry in/out opening 112, and is
placed on the cassette stage 114 such that the wafers 200 are in
their vertical attitudes and the opening of the cassette 110 for
taking wafers in and out is directed upward. Then, the cassette 110
is rotated clockwisely in the vertical direction by 90.degree. to
rearward of the casing so that the wafers 200 in the cassette 110
are in their horizontal attitudes, and the opening of the cassette
110 for taking wafers in and out is directed to rearward of the
casing.
[0109] Next, the cassette 110 is automatically transferred onto a
designated shelf position of the cassette shelves 105 or the
auxiliary cassette shelves 107 by the cassette transfer device 118,
and the cassette 110 is temporarily stored. After that, the
cassette 110 is transferred onto the transfer shelves 123 from the
cassette shelves 105 or the auxiliary cassette shelves 107 by the
cassette transfer device 118, or directly transferred onto the
transfer shelves 123.
[0110] When the cassette 110 is transferred onto the transfer
shelves 123, the wafers 200 are picked up from the cassette 110
through the opening by the tweezers 125c of the wafer loading
device 125a, and the boat 217 located behind a loading chamber 124
is charged with the wafers 200. The wafer loading device 125a which
delivered the wafers 200 to the boat 217 returns to the cassette
110, and charges the boat 217 with the next wafers 200.
[0111] When the boat 217 is charged with a predetermined number of
wafers 200, a lower end of the processing furnace 202 which was
closed by the furnace opening shutter 147 is opened by the furnace
opening shutter 147. Then, the boat 217 which holds a group of
wafers 200 is loaded into the processing furnace 202 by moving the
seal cap 219 upward by the boat elevator 115.
[0112] After the loading, the wafers 200 are subjected to
processing in the processing furnace 202.
[0113] After the processing, the wafers 200 and the cassette 110
are carried outside the casing 111 by reversing the above-described
procedure.
[0114] As explained in the preferred embodiments of the present
invention, according to the preferred embodiments of the present
invention, there is provided a first substrate processing
apparatus, comprising:
[0115] a processing space, defined by a reaction tube made of
quartz, to provide a space in which a substrate is to be
processed;
[0116] a buffer space provided at an inner wall of the reaction
tube and partitioned from the processing space;
[0117] an electrode provided inside the buffer space, the electrode
being used when a first processing gas is plasma-excited, and high
frequency voltage being to be applied to the electrode;
[0118] a heating member to heat the processing space;
[0119] a gas supply member to supply at least the first processing
gas and a second processing gas to the processing space;
[0120] an exhaust member to exhaust an atmosphere in the processing
space; and
[0121] a control member to control at least the electrode, the
heating member, the gas supply member and the exhaust member such
that plasma is generated and the processing space is heated to a
first temperature and supply and exhaust of the first processing
gas and supply and exhaust of the second processing gas are
alternately repeated a plurality of times so that the first and
second processing gases are not mixed with each other in the
processing space when forming a desired film on the substrate, and
the processing space is heated to a second temperature that is
higher than the first temperature without generating plasma and
both the first and second processing gases are supplied to the
processing space when coating a surface of an inner wall of the
processing space with a desired film, wherein
[0122] the first processing gas is to be supplied to the processing
space through the buffer space, and
[0123] the coating film is also to be formed on a surface of an
inner wall of the buffer space.
[0124] According to the preferred embodiments of the present
invention, there is provided a second substrate processing
apparatus, comprising:
[0125] a processing space to provide a space in which a substrate
is to be processed;
[0126] a heating member to heat the processing space;
[0127] a gas supply member to supply at least first and second
processing gases to the processing space;
[0128] an exhaust member to exhaust an atmosphere in the processing
space; and
[0129] a control member to control at least the gas supply member
and the exhaust member such that supply and exhaust of the first
and second processing gases are alternately repeated a plurality of
times so that the first and second processing gases are not mixed
with each other in the processing space when forming a desired film
on the substrate, and both the first and second processing gases
are supplied to the processing space when coating a surface of an
inner wall of the processing space with a desired film.
[0130] Preferably, in the second substrate processing apparatus,
there is provided a third substrate processing apparatus
wherein
[0131] the processing space is defined by a reaction tube made of
quartz,
[0132] an inner wall of the reaction tube is provided with a buffer
space partitioned from the processing space,
[0133] the first processing gas is to be supplied to the processing
space through the buffer space, and
[0134] the coating film is also to be formed on a surface of an
inner wall of the buffer space.
[0135] More preferably, in the third substrate processing
apparatus, there is provided a fourth substrate processing
apparatus wherein
[0136] an electrode is provided inside the buffer space, the
electrode is used when the first processing gas is plasma-excited,
and high frequency voltage is to be applied to the electrode,
[0137] plasma is to be generated by the electrode when forming a
desired film on the substrate, and
[0138] plasma is not to be generated by the electrode when forming
the coating film on the surface of the inner wall of the processing
space.
[0139] Preferably, in the fourth substrate processing apparatus,
there is provided a fifth substrate processing apparatus,
wherein
[0140] when forming a desired film on the substrate, the heating
member heats the processing space to a first temperature, and
[0141] when forming the coating film on the surface of the inner
wall of the processing space, the heating member heats the
processing space at a second temperature that is higher than the
first temperature.
[0142] Most preferably, in the fourth substrate processing
apparatus, there is provided a sixth substrate processing
apparatus, wherein
[0143] the electrode includes two electrodes having long and thin
structures, and
[0144] high frequency electricity of 50 W is to be applied to the
electrode when forming a desired film on the substrate.
[0145] Preferably, in the second substrate processing apparatus,
there is provided a seventh substrate processing apparatus,
wherein
[0146] the gas supply member includes gas supply systems to
independently supply the first and second processing gases, and
[0147] when forming the desired film on the substrate and when
forming the coating film on the surface of the inner wall of the
processing space, the first and second processing gases are to be
supplied to the processing space from the same gas supply
systems.
[0148] Preferably, in the second substrate processing apparatus,
there is provided an eighth substrate processing apparatus,
wherein
[0149] the coating of the desired film on the surface of the inner
wall of the processing space is to be executed after a cleaning
processing is executed by supplying a cleaning gas to the
processing space, and before the desired film is formed on the
substrate.
[0150] According to the other preferred embodiments of the present
invention, there is provided a ninth substrate processing
apparatus, comprising:
[0151] a processing space to provide a space in which a substrate
is to be processed;
[0152] a heating section to heat the processing space;
[0153] a first gas supply section to supply a first processing gas
to the processing space;
[0154] a second gas supply section to supply a second processing
gas to the processing space;
[0155] an exhaust section to exhaust an atmosphere in the
processing space; and
[0156] a control section to control at least the heating section,
the first and second gas supply sections, and the exhaust section
such that when the first or second processing gas is supplied from
one of the first and second gas supply sections, an inert gas is
supplied from the other gas supply section so that the first and
second processing gases are not supplied together to the processing
space when the substrate is accommodated in the processing space,
and
[0157] the control section controls such that both the first and
second processing gases are supplied to the processing space from
the first gas supply section and second gas supply section
respectively when the substrate is not accommodated in the
processing space.
[0158] The entire disclosures of Japanese Patent Application No.
2006-088192 filed on Mar. 28, 2006 including specification, claims,
drawings and abstract are incorporated herein by reference in
its.
[0159] Although various exemplary embodiments have been shown and
described, the invention is not limited to the embodiments shown.
Therefore, the scope of the invention is intended to be limited
solely by the scope of the claims that follow.
[0160] As explained above, according to the preferred embodiments
of the present invention, it is possible to reduce contamination of
a substrate by Na. As a result, the present invention can
especially suitably be utilized for a substrate processing
apparatus which forms a film by an ALD method.
* * * * *