U.S. patent application number 13/948760 was filed with the patent office on 2013-11-21 for substrate processing apparatus.
This patent application is currently assigned to Hitachi Kokusai Electric Inc.. The applicant listed for this patent is Hitachi Kokusai Electric Inc.. Invention is credited to Kiyohisa Ishibashi, Kiyohiko Maeda, Atsushi Moriya, Takaaki Noda.
Application Number | 20130305991 13/948760 |
Document ID | / |
Family ID | 45425768 |
Filed Date | 2013-11-21 |
United States Patent
Application |
20130305991 |
Kind Code |
A1 |
Ishibashi; Kiyohisa ; et
al. |
November 21, 2013 |
SUBSTRATE PROCESSING APPARATUS
Abstract
A method of manufacturing a semiconductor device includes
conveying a first substrate provided with an opposing surface
having insulator regions and a semiconductor region exposed between
the insulator regions and a second substrate provided with an
insulator surface exposed toward the opposing surface of the first
substrate, into a process chamber in a state that the second
substrate is arranged in to face the opposing surface of the first
substrate, and selectively forming a silicon-containing film with a
flat surface at least on the semiconductor region of the opposing
surface of the first substrate by heating an inside of the process
chamber and supplying at least a silicon-containing gas and a
chlorine-containing gas into the process chamber.
Inventors: |
Ishibashi; Kiyohisa;
(Toyama, JP) ; Moriya; Atsushi; (Toyama, JP)
; Noda; Takaaki; (Toyama, JP) ; Maeda;
Kiyohiko; (Toyama, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hitachi Kokusai Electric Inc. |
Tokyo |
|
JP |
|
|
Assignee: |
Hitachi Kokusai Electric
Inc.
Tokyo
JP
|
Family ID: |
45425768 |
Appl. No.: |
13/948760 |
Filed: |
July 23, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13178232 |
Jul 7, 2011 |
8497192 |
|
|
13948760 |
|
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|
|
Current U.S.
Class: |
118/725 |
Current CPC
Class: |
H01L 21/02381 20130101;
H01L 21/02532 20130101; H01L 21/67781 20130101; H01L 21/02587
20130101; H01L 21/0262 20130101; C23C 16/4583 20130101; C23C 16/24
20130101; H01L 21/02636 20130101 |
Class at
Publication: |
118/725 |
International
Class: |
H01L 21/02 20060101
H01L021/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 8, 2010 |
JP |
2010-155937 |
Claims
1. A substrate processing apparatus, comprising: a process chamber
configured to accommodate and process a first substrate provided
with an opposing surface having insulator regions and a
semiconductor region exposed between the insulator regions and a
second substrate provided with an insulator surface exposed toward
the opposing surface of the first substrate; a first gas supply
system configured to supply a silicon-containing gas into the
process chamber; a second gas supply system configured to supply a
chlorine-containing gas into the process chamber; a heater
configured to heat the first substrate and the second substrate;
and a controller configured to control the heater, the first gas
supply system and the second gas supply system such that the
silicon-containing gas and the chlorine-containing gas are supplied
between the first substrate and the second substrate, the second
substrate arranged to face the opposing surface of the first
substrate, to selectively form a silicon-containing film with a
flat surface at least on the semiconductor region of the first
substrate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 13/178,232 filed on Jul. 7, 2011, which claims the benefit
of priority from Japanese Patent Application No. 2010-155937, filed
on Jul. 8, 2010, the entire contents of which are incorporated
herein by reference.
TECHNICAL FIELD
[0002] The present disclosure relates to a method of manufacturing
a semiconductor device and a substrate processing apparatus.
BACKGROUND
[0003] A substrate such as a silicon (Si) wafer may have a
semiconductor region exposed between insulator regions, on which an
epitaxial film of silicon (Si) or silicon germanium (SiGe) is
formed by selective growth. In the case where the selective growth
of an epitaxial film is implemented using a substrate processing
apparatus, e.g., a hot-wall type CVD apparatus, a substrate such as
a silicon (Si) wafer is first loaded into a reaction furnace and
then the reaction furnace is heated or cooled to a target
film-forming temperature. After the reaction furnace has reached
the target film-forming temperature, it takes a certain amount of
stabilization time sufficient to stabilize the internal temperature
of the reaction furnace and the temperature of the inside of the
wafer surface. Thereafter, a source gas is supplied to the reaction
furnace and an epitaxial film of silicon (Si) or silicon germanium
(SiGe) is formed by selective growth.
[0004] Conventionally, to reliably perform selective growth, the
rear surface (opposing surface) of a substrate arranged immediately
above a film-forming target substrate is made of a silicon
(Si)-based material. Referring to Japanese Patent Laid-Open
Publication No. HeiS-206040, for example, the rear surface of a
substrate is made of a silicon (Si)-based material such as
polysilicon (poly-Si). In this case, prior to performing selective
growth of a silicon (Si) film or a silicon germanium (SiGe) film,
the silicon (Si) on the rear surface of the substrate is exposed by
wet-cleaning or dry-cleaning the substrate in the course of a
substrate manufacturing step in which a natural oxide film is
removed from the substrate. Thereafter, an epitaxial film is formed
by selective growth.
[0005] Further, Japanese Patent No. 4394120 discloses a method
without exposing silicon (Si) on the rear surface (opposing
surface) of a substrate, where dummy substrates are charged into a
boat at a pitch twice as great as a normal pitch and the boat is
loaded into a reaction furnace to form polysilicon (poly-Si) films
on the dummy substrates in advance. A product substrate is inserted
between the dummy substrates having the polysilicon (poly-Si) films
formed thereon. Then, the boat is loaded into the reaction furnace
once again to perform selective growth of an epitaxial film.
[0006] In the aforementioned related art in which the opposing
surface of a substrate is made of silicon (Si) or polysilicon
(poly-Si), however, a silicon (Si)-containing film tends to obtain
a stable shape when the silicon (Si)-containing film is formed on a
semiconductor region of a substrate exposed between insulator
regions. This may cause the migration of silicon (Si), and as a
result, the shape of the silicon (Si)-containing film becomes
uneven and sometimes becomes round. This problem is particularly
conspicuous when performing selective growth of a thin silicon (Si)
film or a thin silicon germanium (SiGe) film having a thickness of
about 100 .ANG..
SUMMARY
[0007] The present disclosure provides some embodiments of a method
of manufacturing a semiconductor device and a substrate processing
apparatus, which are capable of selectively forming a
silicon-containing film with a flat surface on a semiconductor
region of a substrate.
[0008] According to one embodiment of the present disclosure, there
is provided a method of manufacturing a semiconductor device,
including: conveying a first substrate provided with an opposing
surface having insulator regions and a semiconductor region exposed
between the insulator regions and a second substrate provided with
an insulator surface exposed toward the opposing surface of the
first substrate, into a process chamber in a state that the second
substrate is arranged to face the opposing surface of the first
substrate; and a second step of selectively forming a
silicon-containing film with a flat surface at least on the
semiconductor region of the opposing surface of the first substrate
by heating an inside of the process chamber and supplying at least
a silicon-containing gas and a chlorine-containing gas into the
process chamber.
[0009] According to another embodiment of the present disclosure,
there is provided a method of manufacturing a semiconductor device,
including: providing a plurality of substrates each provided with a
front surface and a rear surface, the front surface having
insulator regions and a semiconductor region arranged between the
insulator regions, at least the semiconductor region of the front
surface being covered with an oxide film, the rear surface being
covered with an oxide film; removing the oxide film formed on the
semiconductor region of the front surface while keeping intact the
oxide film formed on the rear surface; conveying the substrates, in
which the oxide film formed on the semiconductor region is removed
with the oxide film formed on the rear surface remaining intact,
into a process chamber in a state that the substrates are stacked
one above another at a predetermined interval; and selectively
forming a silicon-containing film on the semiconductor region of
each of the substrates by heating the process chamber and supplying
at least a silicon-containing gas and a chlorine-containing gas
into the process chamber.
[0010] According to still another embodiment of the present
disclosure, there is provided a substrate processing apparatus,
including: a process chamber configured to accommodate and process
a first substrate provided with an opposing surface having
insulator regions and a semiconductor region exposed between the
insulator regions and a second substrate provided with an insulator
surface exposed toward the opposing surface of the first substrate;
a first gas supply system configured to supply a silicon-containing
gas into the process chamber; a second gas supply system configured
to supply a chlorine-containing gas into the process chamber; a
heater configured to heat the first substrate and the second
substrate; and a controller configured to control the heater, the
first gas supply system and the second gas supply system such that
the silicon-containing gas and the chlorine-containing gas are
supplied between the first substrate and the second substrate, the
second substrate arranged to face the opposing surface of the first
substrate, to selectively form a silicon-containing film with a
flat surface at least on the semiconductor region of the first
substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic overall view showing a vertical
low-pressure CVD apparatus according to a first embodiment of the
present disclosure.
[0012] FIG. 2 is a schematic view showing a reaction furnace
according to the first embodiment.
[0013] FIG. 3 is a schematic vertical section view of a boat in
which a wafer transfer operation is performed, and dummy wafers
each having an exposed insulator surface are placed immediately
above product wafers, according to a second embodiment of the
present disclosure.
[0014] FIGS. 4A and 4B are schematic views showing different gas
reactions according to the first embodiment, which depends on a
difference in the type of an opposing surface.
[0015] FIGS. 5A and 5B are schematic views showing different
epitaxial films according to the first embodiment, which depends on
a difference in the type of an opposing surface.
[0016] FIGS. 6A, 6B and 6C are views showing an oxide film removal
process for removing an oxide film formed on the front surface of a
wafer and for removing an oxide film formed on the rear surface of
a wafer according to the second embodiment.
[0017] FIG. 7 is a section view showing a substrate cleaning
apparatus for implementing the oxide film removal process according
to the second embodiment.
[0018] FIG. 8 is a schematic overall view showing a batch-type
low-pressure CVD apparatus according to a third embodiment of the
present disclosure.
[0019] FIG. 9 is a schematic vertical section view of a MOSFET
structure having a typical elevated source/drain.
DETAILED DESCRIPTION
[0020] As mentioned above, the migration of silicon (Si) may easily
occur and thus the shape of a silicon-containing film becomes
uneven, according to the related art method in which a
silicon-containing film is allowed to selectively grow on a
semiconductor region of a substrate which is provided so that
another substrate exposes a silicon-based film formed on a surface
oppo sing thereto. According to one embodiment of the present
disclosure, a surface of a second substrate opposing a first
substrate is formed of an insulator surface. A silicon
(Si)-containing gas and a chlorine (Cl)-containing gas are supplied
into a reaction chamber. If the surface of the second substrate
opposing to the first substrate is formed of the insulator surface,
the migration of silicon (Si) is suppressed by the chlorine
components contained in the chlorine (Cl)-containing gas. This
makes it possible to selectively form, within the reaction chamber,
a silicon-containing film with a flat surface on a semiconductor
region of the first substrate in a reliable manner.
[Method of Manufacturing a Semiconductor Device]
[0021] Hereinafter, certain embodiments of a method of
manufacturing a semiconductor device will be described in
detail.
One Embodiment
[0022] A method of manufacturing a semiconductor device according
to one embodiment of the present disclosure includes: providing a
first substrate provided with an opposing surface having insulator
regions and a semiconductor region exposed between the insulator
regions and a second substrate provided with an insulator surface
exposed toward the opposing surface of the first substrate;
arranging the second substrate to face the opposing surface of the
first substrate; and selectively forming a silicon-containing film
with a flat surface at least on the semiconductor region of the
first substrate by supplying a silicon-containing gas and a
chlorine-containing gas to at least between the first substrate and
the second substrate.
[0023] The insulator regions of the first substrate are exposed.
The semiconductor region of the first substrate is exposed between
the insulator regions. The second substrate is arranged to face the
first substrate. The insulator surface of the second substrate is
exposed toward the opposing surface of the first substrate. The
first substrate and the second substrate are, e.g., silicon (Si)
wafers. The insulator regions of the first substrate and the
insulator surface of the second substrate are made of, e.g., a
silicon oxide (SiO) material or a silicon nitride (SiN) material.
The semiconductor region of the first substrate is made of, e.g., a
silicon (Si) material.
[0024] The silicon-containing film is, e.g., an epitaxial film of
silicon (Si) or silicon germanium (SiGe). The silicon-containing
film may be formed at least on the first substrate. Alternatively,
the silicon-containing film may be formed not only on the first
substrate but also on the second substrate. In this case, similar
to the first substrate, the silicon-containing film of the second
substrate is selectively formed on a semiconductor region thereof.
The first substrate and the second substrate may be different ones
or may be identical with each other.
[0025] In case where the silicon-containing film to be formed is a
silicon (Si) film, the silicon (Si)-containing gas may be, e.g., a
silane (SiH.sub.4) gas, a disilane (Si.sub.2H.sub.6) gas or a
dichlorosilane (SiH.sub.2Cl.sub.2) gas. The chlorine
(Cl)-containing gas may be, e.g., a chlorine (Cl.sub.2) gas or a
hydrogen chloride (HCl) gas which differs from the silicon
(Si)-containing gas. In addition, a diluent gas (e.g., a H.sub.2
gas) may be supplied between the first substrate and the second
substrate. In case where the silicon-containing film to be formed
is a silicon germanium (SiGe) film, the silicon (Si)-containing gas
is added with germane (GeH.sub.4).
[0026] According to the method of the present embodiment, if a
silicon (Si)-containing gas and a chlorine (Cl)-containing gas are
supplied between the first substrate and the second substrate,
chlorine (Cl) components exhibiting increased surface coverage are
chlorine (Cl)-terminated in a growth region, namely in the
semiconductor region of the first substrate. This is because the
second substrate having an insulator film on its surface opposing
to the first substrate is arranged to face the first substrate.
Thus, the migration of silicon (Si) is suppressed, which makes it
possible to selectively form a silicon (Si)-containing film with a
flat surface at least on the semiconductor region of the first
substrate in a reliable manner.
Another Embodiment
[0027] A method of manufacturing a semiconductor device according
to another embodiment of the present disclosure includes first and
second steps of forming a silicon (Si)-containing film. The first
step is configured to convey a first substrate provided with an
opposing surface having insulator regions and a semiconductor
region exposed between the insulator regions and a second substrate
provided with an insulator surface exposed toward the opposing
surface of the first substrate, into a reaction chamber in a state
that the second substrate is arranged to face the opposing surface
of the first substrate. The second step is configured to
selectively form a silicon-containing film with a flat surface at
least on the semiconductor region of the opposing surface of the
first substrate by heating the inside of the reaction chamber and
supplying at least a silicon-containing gas and a
chlorine-containing gas into the reaction chamber.
[0028] The silicon-containing film is, e.g., an epitaxial film of
silicon (Si) or silicon germanium (SiGe). The silicon-containing
film may be formed at least on the first substrate, more
particularly on the semiconductor region of the first substrate.
Accordingly, a dummy substrate having an insulator surface exposed
toward the opposing surface of the first substrate can be used as
the second substrate, and a product substrate having insulator
regions and a semiconductor region exposed between the insulator
regions can be used as the first substrate. In one embodiment, the
silicon-containing film may be formed not only on the first
substrate but also on a semiconductor region of the second
substrate. In this case, identical product substrates can be used
as the first substrate and the second substrate. The product
substrate may refer to a substrate from which semiconductor devices
such as ICs are actually manufactured. The dummy substrate may
refer to a substrate used to prevent deterioration of film
formation. For this purpose, two dummy substrates are arranged
above and below the product substrate so that the product substrate
can be interposed therebetween.
[0029] According to the method of the present embodiment, if a
silicon (Si)-containing gas and a chlorine (Cl)-containing gas are
supplied into a heated reaction chamber, chlorine (Cl) components
exhibiting increased surface coverage are chlorine (Cl)-terminated
at least in a growth region, namely in the semiconductor region of
the first substrate. This is because the second substrate having an
insulator film on its surface opposing to the first substrate is
arranged to face the first substrate. Thus, the migration of
silicon (Si) is suppressed, which makes it possible to selectively
form a silicon (Si)-containing film with a flat surface at least on
the semiconductor region of the first substrate in a reliable
manner.
[0030] In the second step mentioned above, a material formed by
decomposition of the silicon-containing gas and the
chlorine-containing gas in a gaseous layer within the reaction
chamber may be adsorbed to at least the rear surface of the second
substrate and the semiconductor region of the first substrate. In
this regard, the gases decomposed in the gaseous layer within the
reaction chamber may be, e.g., a silane (SiH.sub.4) gas, a disilane
(Si.sub.2H.sub.6) gas, a dichlorosilane (SiH.sub.2Cl.sub.2) gas or
a germane (GeH.sub.4) gas. The material formed by decomposition of
the silicon-containing gas and the chlorine-containing gas in the
gaseous layer within the reaction chamber may be, e.g., silicon
(Si) or silicon germanium (SiGe).
[0031] Since the material formed by decomposition is adsorbed to
the rear surface of the second substrate and the semiconductor
region of the first substrate, it is possible to selectively form a
silicon-containing film with a flat surface on the semiconductor
region of the first substrate in a reliable manner.
Further Embodiment
[0032] While the silicon (Si)-containing film is formed at least on
the first substrate in the embodiments described above, an
additional silicon (Si)-containing film may be formed on the second
substrate. In this case, the second substrate is configured such
that a semiconductor region is exposed between insulator regions on
the opposite surface of the second substrate from the opposing
surface of the first substrate. This makes it possible to
selectively form a silicon-containing film with a flat surface even
on the semiconductor region of the second substrate in a reliable
manner.
Still Further Embodiment
[0033] While the silicon (Si)-containing film is formed on the
first substrate or the second substrate in the embodiments
described above, the first substrate and the second substrate may
be identical with each other and a plurality of identical
substrates may be conveyed into a reaction chamber to form silicon
(Si)-containing films on the respective substrates.
[0034] To this end, the method of manufacturing a semiconductor
device according to the present embodiment may include: providing a
plurality of substrates, the front surface of the ea ch substrates
having insulator regions and a semiconductor region arranged
between the insulator regions, at least the semiconductor region of
the front surface being covered with an oxide film, the rear
surface of the each substrates being covered with an oxide film;
removing the oxide film formed on the semiconductor region of the
front surface of each of the substrates while keeping intact the
oxide film formed on the rear surface of each of the substrates;
and conveying the substrates, in which the oxide film formed on the
semiconductor region is removed while the oxide film formed on the
rear surface remaining intact, into a reaction chamber in a state
that the substrates are stacked one above another at a
predetermined interval.
[0035] According to this method, the substrates in which the oxide
film formed on the rear surface remains intact can be stacked one
above another. This makes it possible to simultaneously form,
within the reaction chamber, silicon-containing films on the
semiconductor regions of a plurality of substrates in a reliable
manner.
Yet Still Further Embodiment
[0036] A substrate holder can be used to convey a plurality of
stacked substrates into a reaction chamber. To this end, in the
present embodiment, a substrate holder holding the substrates
vertically stacked one above another at a predetermined interval
may be conveyed into the reaction chamber in the conveying step
mentioned above, each of the substrates provided with a front
surface having insulator regions and a semiconductor region exposed
between the insulator regions and a rear surface formed of an
exposed insulator surface. According to this method,
silicon-containing films are formed on the semiconductor regions of
the substrates held by the substrate holder within the reaction
chamber. This makes it possible to process an increased number of
substrates that can be conveyed by the substrate holder, thereby
greatly enhancing the throughput.
[0037] In one embodiment, the insulator regions and the
semiconductor region may be formed at different heights. If the
insulator regions are substantially flush with the semiconductor
region, the silicon (Si)-containing layers selectively formed on
the semiconductor region can have a flat surface.
[0038] [Substrate Processing Apparatus]
[0039] A substrate processing apparatus for implementing one
process of the above-described semiconductor device manufacturing
method is configured as follows.
One Embodiment
[0040] A substrate processing apparatus according to one embodiment
of the present disclosure includes a reaction chamber, a first gas
supply system, a second gas supply system, a heater and a
controller.
[0041] The reaction chamber is defined within a process vessel. A
first substrate and a second substrate are arranged to be processed
within the reaction chamber. The first gas supply system serves to
supply a silicon-containing gas into the reaction chamber. The
second gas supply system serves to supply a chlorine-containing gas
into the reaction chamber. The heater serves to heat the substrates
to a processing temperature. The heater is configured by, e.g., a
resistance heater.
[0042] The controller is configured to control the heater, the
first gas supply system and the second gas supply system such that
a silicon-containing gas and a chlorine-containing gas are supplied
between a first substrate, which is provided with an opposing
surface having insulator regions and a semiconductor region exposed
between the insulator regions, and a second substrate, which is
provided with an exposed insulator surface and arranged in an
opposing relationship with the opposing surface of the first
substrate, to selectively form a silicon-containing film with a
flat surface on the semiconductor region of the first
substrate.
[0043] With this configuration, the first substrate and the second
substrate arranged within the reaction chamber are heated by the
heater controlled by the controller. If the silicon-containing gas
and the chlorine-containing gas are supplied between the first
substrate and the second substrate by the first gas supply system
and the second gas supply system under the control of the
controller, chlorine components exhibiting increased surface
coverage are chlorine (Cl)-terminated in a growth region, namely in
the semiconductor region of the first substrate. Thus, the
migration of silicon (Si) is suppressed, which makes it possible to
selectively form a silicon (Si)-containing film with a flat surface
at least on the semiconductor region of the first substrate in a
reliable manner.
Specific Example
[0044] The substrate processing apparatus according to one
embodiment of the present disclosure will be described in detail
with reference to the accompanying drawings.
[0045] FIG. 1 is a schematic vertical section view showing a
hot-wall type vertical low-pressure CVD apparatus, one specific
example of the substrate processing apparatus for implementing one
process of the semiconductor device manufacturing method according
to the present embodiment. FIG. 2 is a schematic vertical section
view showing a reaction furnace employed in the hot-wall type
vertical low-pressure CVD apparatus according to the present
embodiment.
[0046] (Hot-Wall Type Vertical Low-Pressure CVD Apparatus)
[0047] As shown in FIG. 1, the hot-wall type vertical low-pressure
CVD apparatus 180 according to the present embodiment includes a
reaction furnace 100, a control device 141 (used as a controller),
a gas supply device 142 and a vacuum exhaust device 143. The
reaction furnace 100 includes a reaction vessel 104, a heater 101
provided outside the reaction vessel 104 and an insulating material
102 provided to cover the heater 101 and the reaction vessel
104.
[0048] An exhaust pipe 116 is attached to the sidewall of the
reaction vessel 104 and is connected to the vacuum exhaust device
143. A nozzle 108 is provided to pass through the reaction vessel
104. A supply pipe 115 connected to the nozzle 108 is provided
outside the reaction vessel 104. The supply pipe 115 is connected
to the gas supply device 142. A source gas for selective growth of
a Si film or a SiGe film is supplied to the nozzle 108 through the
supply pipe 115 and is introduced into the reaction vessel 104 from
the nozzle 108. The gas introduced into the reaction vessel 104 is
exhausted from the exhaust pipe 116 by the vacuum exhaust device
143.
[0049] A boat 105 (used as a substrate holder) is loaded into and
unloaded from the reaction vessel 104. If the boat 105 is lifted up
and loaded into the reaction vessel 104, the furnace opening of the
reaction vessel 104 is closed. If the boat 105 is lowered down and
unloaded from the reaction vessel 104, the furnace opening is
closed by a gate valve 117. A transfer machine 151 is provided for
transferring wafers 130 between the boat 105 (which is unloaded
from the reaction furnace 100) and a wafer cassette 152
accommodating the wafers 130.
[0050] (Reaction Furnace)
[0051] The detailed configuration of the reaction furnace 100 is
shown in FIG. 2. The reaction furnace 100 includes a base 112, a
manifold 111 provided above the base 112, a reaction tube 103 and a
heater 101 provided outside the reaction tube 103. A reaction
chamber 109 is defined within the reaction tube 103. The entire
inside of the reaction tube 103 is heated by the heater 101. The
reaction tube 103 is provided on an upper flange 118 of the
manifold 111. The reaction vessel 104 mentioned above is configured
by the reaction tube 103 and the manifold 111.
[0052] The heater 101 for heating the reaction tube 103 are divided
into five elements, e.g., a top heater 101a, a central upper heater
101b, a center heater 101c, a central lower heater 101d and a
bottom heater 101e. The internal temperature of the reaction
furnace 100 is controlled by the control device 141. Alternatively,
the heater 101 may not be divided but provided as one integrated
body.
[0053] The boat 105 is placed on a seal cap 113. The boat 105 held
by the seal cap 113 is loaded through the opening 120 of the base
112. The opening 120 is configured to be closed by the seal cap 113
as the seal cap 113 moves upward. When the opening 120 is closed,
the boat 105 is positioned within the reaction tube 103. The boat
105 is rotated by a rotation mechanism 114. The wafers 130 are
vertically stacked one above another in the boat 105. The inside of
the reaction tube 103 serves as the reaction chamber 109 within
which the wafers 130 are subjected to processing. Heat shield
panels 107 are arranged in the lower portion of the boat 105 at a
height corresponding to the height of the manifold 111. Once the
seal cap 113 is moved down and the boat 105 is unloaded from the
reaction vessel 104, the opening 120 of the base 112 is closed by
the gate valve 117 (see FIG. 1).
[0054] First and second nozzles 108a and 108b are provided within
the reaction vessel 104 along the boat 105. The first and second
nozzles 108a and 108b are inserted into the reaction tube 103 from
the lower portion of the manifold 111. The first nozzle 108a
composes a first gas supply system for supplying a
silicon-containing gas. The second nozzle 108b composes a second
gas supply system for supplying a chlorine-containing gas. A nozzle
for supplying a carrier gas therethrough is also provided but is
not shown for simplicity. An exhaust pipe 116 is attached to the
sidewall of the manifold 111.
[0055] For the selective growth of a film of silicon (Si) or
silicon germanium (SiGe), a silicon (Si)-containing gas as a source
gas is introduced from the first nozzle 108a. In case of selective
growth of a silicon (Si)-containing film, the silicon
(Si)-containing gas may be, e.g., a silane (SiH.sub.2) gas, a
disilane (Si.sub.2H.sub.6) gas or a dichlorosilane
(SiH.sub.2Cl.sub.2) gas. In case of selective growth of a silicon
germanium (SiGe)-containing film, the silicon (Si)-containing gas
is added with a germanium (Ge) such as germane (GeH.sub.4).
[0056] In addition to the silicon (Si)-containing gas and the
germanium (Ge)-containing gas, a chlorine (Cl)-containing gas is
introduced from the second nozzle 108b to assure increased
selectivity. A chlorine (Cl.sub.2) gas or a hydrogen chloride (HCl)
gas may be used as the chlorine (Cl)-containing gas.
[0057] The source gas introduced into the top portion of the
reaction tube 103 from the first nozzle 108a or the second nozzle
108b flows down within the reaction tube 103 past the wafers 130 as
substrates stacked one above another. Then, the source gas is
exhausted from the exhaust pipe 116 arranged in the lower portion
of the reaction tube 103.
[0058] A temperature control unit configured to control the heater
101, a gas flow rate control unit configured to control the gas
supply device 142, a pressure control unit configured to control
the vacuum exhaust device 143 and a drive control unit configured
to control the rotation mechanism 114, the gate valve 117 and the
transfer machine 151 are electrically connected to a main control
unit configured to control the entire operation of the hot-wall
type vertical low-pressure CVD apparatus 180. The temperature
control unit, the gas flow rate control unit, the pressure control
unit and the drive control unit configure a controller 141.
[0059] In the hot-wall type vertical low-pressure CVD apparatus 180
described above, the wafers (Si substrates) 130 held in the wafer
cassette 152 are transferred from the wafer cassette 152 to the
boat 105 by the transfer machine 151. If all the wafers 130 are
completely transferred, the boat 105 is loaded into the reaction
vessel 104. The inside of the reaction vessel 104 is depressurized
by the vacuum exhaust device 143. Then, the wafers 130 are heated
by the heater 101 to a desired temperature, e.g., 400.degree. C. or
less. If the temperature becomes stable, a source gas is supplied
by the gas supply device 142 through the supply pipe 115 and the
nozzle 108. As a result, a CVD reaction is caused to occur so that
a silicon (Si) film or a silicon germanium (SiGe) film as a
semiconductor film with a flat surface can grow on each of the
wafers (Si substrates) 130 in a reliable manner.
[0060] The following is a description on a first embodiment of a
mechanism by which a silicon (Si)-containing film with a flat
surface is selectively formed on the semiconductor region of the
first substrate, with reference to the accompanying drawings.
First Embodiment
[0061] This embodiment is related to a case in which a product Si
wafer is used as a first substrate and a dummy Si wafer differing
from the product Si wafer is used as a second substrate.
[0062] FIG. 3 is a schematic explanation view showing a boat
according to one embodiment of the present disclosure and a
transfer machine configured to transfer a plurality of wafers to
and from the boat. The boat 105 unloaded from the reaction furnace
waits below the reaction furnace. The transfer machine 151 is
provided adjacent to the boat 105. The transfer machine 151 is
configured to hold a plurality of, e.g., five, wafers 130 with a
corresponding number of tweezers 133 and transfer them to the boat
105 at one time.
[0063] The wafers 130 include product Si wafers 131 and dummy Si
wafers 132. The product Si wafers 131 may refer to wafers from
which semiconductor devices such as ICs are actually manufactured.
The dummy Si wafers 132, which differ from the product Si wafers
131, are arranged above and below the respective product Si wafers
131 so that the product Si wafers 131 can be interposed between the
dummy Si wafers 132. The dummy Si wafers 132 serve to prevent heat
from dissipating from around the product Si wafers 131 and prevent
fine particles or contaminants scattering around the product Si
wafers 131 from adhering thereto. The dummy Si wafers 132 may refer
to wafers for preventing deterioration of film formation which may
be caused by turbulent gas flow or uneven temperature distribution.
In FIG. 3, the dummy Si wafers 132 are vertically stacked one above
another in the boat 105. The respective product Si wafers 131
transferred by the transfer machine 151 are inserted and arranged
between the corresponding upper and lower dummy Si wafers 132. As a
result, each of the dummy Si wafers 132 provided with an exposed
insulator surface is arranged immediately above a corresponding one
of the product Si wafers 131. The dummy Si wafers mentioned above
are often referred to as sandwiching dummy wafers because they are
configured to sandwich the product Si wafers.
[0064] In this embodiment, the product Si wafers 131 are silicon
(Si) wafers each provided with a front surface (major surface)
having a semiconductor silicon (Si) region to be subjected to
selective growth. The semiconductor silicon (Si) region is formed
between insulator regions made of silicon oxide (SiO.sub.2) or
silicon nitride (SiN). The respective dummy Si wafers 132 are
arranged in a parallel to face the major surfaces of the
corresponding product Si wafers 131 to be subjected to selective
growth. Dummy silicon (Si) wafers each having a nitride film (a SiN
film or a Si.sub.3N.sub.4 film) exposed at least on the rear
surface thereof are prepared as the dummy Si wafers 132.
[0065] In one process of a semiconductor device manufacturing
method to form a silicon (Si)-containing film, at least one product
Si wafer and at least one dummy Si wafer having a SiN film (or a
Si.sub.3N.sub.4 film) exposed at least on the rear surface thereof
are accommodated within a reaction chamber in such a state that the
rear surface of the dummy Si wafer is arranged to face the surface
of the product Si wafer to be subjected to selective growth.
[0066] Next, the product Si wafer and the dummy Si wafer
accommodated within the reaction chamber are heated by a heater
arranged outside the reaction chamber. Concurrently, a process gas
is supplied into the reaction chamber from a process gas supply
system while exhausting the process gas out of the reaction
chamber. At this time, a material formed by decomposition of the
process gas in a gaseous layer within the reaction chamber is
adsorbed to the SiN film (or the Si.sub.3N.sub.4 film) on the rear
surface of the dummy Si wafer and also to the Si region of the
product Si wafer, thereby allowing a Si-containing film to
selectively grow on the Si region.
[0067] In case of selective growth of Si or SiGe, the selectively
growing silicon (Si)-containing film may be, e.g., an elevated
source/drain of a MOSFET.
[0068] FIG. 9 is a schematic vertical section view showing a MOSFET
310 having an elevated source/drain formed thereon. On a
device-forming silicon region 311 surrounded by a device isolation
region 312, a gate electrode 320 is formed through a gate
insulation film 317. A sidewall 318 is formed on the side surface
of the gate electrode 320. A gate protection film 319 is formed on
the top surface of the gate electrode 320. In the device-forming
silicon region 311, a source 313 and a drain 314 are formed in a
self-aligning manner with respect to the gate electrode 320. An
elevated source 315 and an elevated drain 316 are selectively
formed only on the source 313 and the drain 314. The elevated
source 315 and the elevated drain 316 are formed by a technique
generally referred to as selective growth, in which Si or SiGe is
allowed to epitaxially grow only on the source 313 and the drain
314 exposing Si while any material is not allowed to grow on the
device isolation region 312 exposing SiO.sub.2 or SiN.
[0069] In case where a silicon (Si)-containing film such as an
elevated source or an elevated drain is allowed to selectively grow
on the silicon (Si) region at a relatively great thickness, the
degree of selective growth depends largely on whether the opposing
surface (e.g., a substrate surface opposing the selectively grown
film) is a silicon-based film or an insulator-based film.
[0070] FIGS. 4A and 4B are schematic views showing different gas
reactions in case where the opposing surface is formed of a silicon
(Si)-based material such as polysilicon (poly-Si) or the like (FIG.
4A) and in case where the opposing surface is formed of an
insulator-based material such as SiN or SiO.sub.2 (FIG. 4B). If a
silicon (Si)-containing film such as an elevated source/drain or an
embedded source/drain needs to have a thickness of, e.g., 500 .ANG.
or more in the selective growth of Si or SiGe, the surface of the
dummy Si wafer 132a opposing the product Si wafer 131 is made of a
silicon (Si)-based material such as polysilicon (poly-Si) or the
like as shown in FIG. 4A. This enables active species (e.g.,
SiH.sub.4) to be adsorbed to the opposing surface of the product Si
wafer 131, which makes it possible to maintain selectivity. On the
other hand, if the surface of the dummy Si wafer 132b opposing the
product Si wafer 131 is made of an insulator-based material such as
SiN or SiO.sub.2 (FIG. 4B), it is highly probable that a reaction
with silicon nitride (SiN) or silicon oxide (SiO.sub.2) occurs
above the product Si wafer. This shortens a latent period, which
prevents the selective growth or the thickness of a film that can
be formed by the selective growth becomes extremely small.
[0071] In contrast, when the selective growth of silicon (Si) or
silicon germanium (SiGe) is performed to form a thin film, an
insulator-based film of silicon nitride (SiN) or silicon oxide
(SiO.sub.2) may be exposed on the surface of the dummy Si wafer
opposing the product Si wafer. For example, when a silicon
(Si)-containing film is caused to grow on the semiconductor region
of the product Si wafer exposed between the insulator regions to
have a height greater than the height of the insulator regions, the
migration of silicon (Si) is suppressed even if the selective
growth of silicon (Si) or silicon germanium (SiGe) is performed to
form a thin film of, e.g., about 100 .ANG.. Therefore, if the
surface of the dummy Si wafer opposing the product Si wafer is made
of silicon nitride (SiN) or silicon oxide (SiO.sub.2) and if a
silicon-containing gas and a chlorine-containing gas are supplied
into the reaction chamber, it becomes possible to form a flat
epitaxial film in a reliable manner.
[0072] The above process will be described in more detail with
reference to FIG. 5. The source gas used in this example is a
silane (SiH.sub.4) gas added with a germane (GeH.sub.4) gas and a
hydrogen chloride (HCl) gas. Under the epitaxial growth conditions
of predetermined temperature, pressure and flow rate, the source
gas is thermally decomposed on the semiconductor region (silicon
(Si) region) of the product Si wafer, thereby epitaxially and
selectively growing a monocrystalline film of silicon germanium
(SiGe) only on the silicon (Si) region.
[0073] As shown in FIG. 5A, if the surface of the dummy Si wafer
132a opposing the product Si wafer 131 is made of a silicon
(Si)-based material such as polysilicon (poly-Si) or the like, a
SiGe epitaxial film 165 formed on the silicon (Si)-made
semiconductor region 161 of the product Si wafer 131 (which is
exposed between the insulator regions 163 made of silicon oxide
(SiO.sub.2) or silicon nitride (SiN)) may not be maintained to be
flat, but become a round shape (e.g., a bulging or convex shape).
This is because the Cl components of a source gas, e.g., a silane
(SiH.sub.4) gas, are consumed not only by the semiconductor region
161, i.e., the growth surface, of the product Si wafer 131 but also
by the rear surface of the dummy Si wafer 132a positioned above the
semiconductor region 161, consequently accelerating the migration
of silicon (Si) and reducing the surface coverage of the Cl
components on the product Si wafer 131.
[0074] In contrast, as shown in FIG. 5B, if the surface of the
dummy Si wafer opposing the product Si wafer 131 is made of an
insulator-based film of silicon nitride (SiN) or silicon oxide
(SiO.sub.2), a flat SiGe epitaxial film 166 is formed on the
silicon (Si)-made semiconductor region 161 of the product Si wafer
131 exposed between the insulator regions 163 made of silicon oxide
(SiO.sub.2) or silicon nitride (SiN). This is because the Cl
components of silane (SiH.sub.4) are sufficiently supplied onto the
product Si wafer 131. For this reason, the Cl components with
increase surface coverage are Cl-terminated on the growth region of
the product Si wafer 131 during the selective growth of silicon
(Si) or silicon germanium (SiGe), thereby suppressing the migration
of silicon (Si). The Cl-terminated Cl components are substituted by
active species such as silane (SiH.sub.4) or germane (GeH.sub.4),
which eliminates the possibility that the Cl components remain in
the film. According to the above process, the surface of the dummy
Si wafer facing the product Si wafer is formed of an insulation
film, thereby improving the flatness of the film formed on the
semiconductor region of the product Si wafer.
[0075] Although germanium (Ge) is used as a source material in the
example shown in FIGS. 5A and 5B, silicon (Si) may be used instead
of germanium (Ge). In this case, germanium (Ge) in the plan crystal
structure diagram shown in FIGS. 5A and 5B may be replaced by
silicon (Si). With this arrangement, a silicon (Si) epitaxial film
may be formed instead of the silicon germanium (SiGe) epitaxial
film formed in the above example.
(Process Conditions)
[0076] In the first embodiment described above, the process
conditions for the selective growth of silicon (Si) or silicon
germanium (SiGe) may be set as follows. For example, the flow rate
of the silicon (Si)-containing gas may be in a range of from 50
sccm to 1,000 sccm, the flow rate of the germanium (Ge)-containing
gas may be in a range of from 0 sccm to 500 sccm, the flow rate of
the chlorine (Cl)-containing gas may be in a range of from 10 sccm
to 200 sccm, the flow rate of the hydrogen (H.sub.2) gas may be in
a range of from 0 slm to 20 slm, the internal temperature of the
reaction chamber may be in a range of from 450.degree. C. to
700.degree. C. and the internal pressure of the reaction chamber
may be in a range of from 10 Pa to 100 Pa.
[Effects of the First Embodiment]
[0077] According to the present embodiment, the first substrate and
the second substrate are used. The second substrate is arranged
immediately above the first substrate. The rear surface of the
second substrate is formed of an insulation film (SiN or
SiO.sub.2). In this state, at least a silane (SiH.sub.4) gas and a
hydrogen chloride (HCl) gas are supplied between the first
substrate and the second substrate. As a result, a silicon (Si)
film is allowed to selectively grow on the Si region of the front
surface of the first substrate, and at this time, the migration of
silicon (Si) is suppressed by the chlorine (Cl) components
contained in the hydrogen chloride (HCl) gas. Accordingly, it is
possible to form a silicon (Si) film with a flat surface in a
reliable manner.
[0078] In the first embodiment described above, the insulator
surface of the second substrate is exposed toward the opposing
surface of the first substrate. In this configuration, the rear
surface of the first substrate, i.e., the product wafer, may be
formed of SiN or SiO.sub.2. However, if a Si-based film is exposed
on the rear surface of the product wafer, the opposing surface of
the product wafer, which is arranged immediately above the rear
surface of the product wafer, needs to be formed of an insulation
film of SiN or SiO.sub.2.
Second Embodiment
[0079] The following is a description on certain methods (first to
third methods) of forming a substrate surface opposing the product
Si wafer with an insulation film as according to a second
embodiment.
[0080] (First Method)
[0081] In this method, the first substrates and the second
substrates are different types of substrates (see FIG. 3). Only the
second substrates are subjected to insulation film formation
processing in advance so that the opposing surface of each of the
second substrates has an insulator surface.
[0082] In case where the respective dummy Si wafers (sandwiching
dummy wafers) 132 each having a SiN film or a SiO.sub.2 film formed
as a insulator surface are arranged immediately above the
corresponding product Si wafers 131, the boat 105 holding the dummy
Si wafers 132 stacked one above another at a pitch twice as great
as a normal pitch is loaded into the reaction furnace 100. Prior to
loading the product Si wafers 131, a source gas is supplied to form
insulation films such as SiN films or SiO.sub.2 films on the front
and rear surfaces of the respective dummy Si wafers 132 including
the opposing surfaces. Thereafter, the boat 105 is taken out from
the reaction furnace 100. Subsequently, the product Si wafers 131
are inserted between the dummy Si wafers 132 held by the boat 105.
The boat 105 is loaded into the reaction furnace 100 once again to
perform selective growth of silicon-containing films on the product
Si wafers 131. According to this method, the reaction furnace with
the same configuration as the furnace for formation of
silicon-containing films is used to form the insulation films. This
makes it possible to reliably form insulation films on the surfaces
of the dummy Si wafers opposing to the product Si wafers.
[0083] (Second Method)
[0084] This method is the same as the first method in that the
first substrates and the second substrates are different types of
substrates, but differs from the first method in that the opposing
surfaces of the second substrates are formed of insulator surfaces
by subjecting the reaction tube accommodating the second substrates
to insulation film formation processing in advance.
[0085] In particular, the boats each holding the dummy Si wafers
stacked one above another at a pitch twice as great as a normal
pitch are loaded into the respective reaction tube in advance. The
boat and the dummy Si wafers loaded into the reaction tube is
coated with insulation films such as SiN films or SiO.sub.2 films.
Thereafter, the boat is taken out from the reaction tube.
Subsequently, the product Si wafers are inserted between the dummy
Si wafers held by the boat. The boat is loaded into the reaction
tube once again to perform selective growth of silicon-containing
films on the product Si wafers.
[0086] According to this method, the insulation films are coated
not only on the dummy Si wafers but also the boat and the reaction
tube. This makes it easy to perform the film coating process as
compared with the first method in which only the dummy Si wafers
are coated with the insulation films. Inasmuch as the insulator
surfaces are exposed not only in the dummy Si wafers arranged
immediately above the product Si wafers but also in the members
arranged around the product Si wafers, it is possible to surely
suppress the migration of silicon (Si) and to selectively form,
within the reaction chamber, a silicon-containing film with a flat
surface on the semiconductor region of the first substrate in a
reliable manner.
[0087] (Third Method)
[0088] In this method, the same type of the product Si wafers are
used as either of the first substrate and the second substrate. The
front surface of each of the product Si wafers of the same type is
formed to have a semiconductor region and the rear surface thereof
is formed to have an insulation film. To this end, the third method
includes: providing a plurality of product Si wafers, the front
surface of each of the product Si wafers having insulator regions
and a semiconductor region arranged between the insulator regions,
at least the semiconductor region of the front surface being
covered with an oxide film, the rear surface of each of the product
Si wafers being covered with an oxide film; removing the oxide film
formed on the semiconductor region of the front surface of each of
the product Si wafers while keeping intact the oxide film formed on
the rear surface of each of the product Si wafers; and conveying
the product Si wafers, in which the oxide film formed on the
semiconductor region is removed with the oxide film formed on the
rear surface remaining intact, into a reaction chamber in a state
that the product Si wafers are stacked one above another at a
predetermined interval.
[0089] According to this method, the opposing surface of a
substrate (e.g., a rear surface of a upper product Si wafer
opposing a front surface of a lower product Si wafer) can be formed
to have an insulation film by keeping intact the oxide film formed
on the rear surface of each of the product Si wafers. Since the
product Si wafers in which the oxide film formed on the rear
surface remains intact are stacked one above another in the boat,
it is possible to form, within the reaction chamber,
silicon-containing films on the semiconductor regions of a
plurality of substrates (e.g., product Si wafers) at one time.
[0090] In the oxide film removing operation mentioned above, water
may be supplied to the rear surface of each of the product Si
wafers while supplying a hydrofluoric-acid-containing material to
the front surface of each of the product Si wafers, in order to
remove the oxide film formed on the semiconductor region of the
front surface while keeping intact the oxide film formed on the
rear surface. If water is supplied to the rear surface while
supplying the hydrofluoric-acid-containing material to the front
surface, it is possible to prevent the hydrofluoric-acid-containing
material from flowing toward the rear surface and thus effectively
keep intact the oxide film formed on the rear surface.
[0091] One process of a semiconductor device manufacturing method
incorporating the third method mentioned above may be implemented
as follows. In particular, the third method includes: a first step
of providing a plurality of product Si wafers having front and rear
surfaces with oxide films formed thereon and cleaning the front and
rear surfaces of the product Si wafers with DHF (diluted
hydrofluoric acid) to remove the oxide films; a second step of
accommodating the product Si wafers within a reaction chamber in a
state that the product Si wafers having Si regions exposed on the
rear surfaces thereof are stacked one above another with the front
surface of each of the product Si wafers arranged in an opposing
relationship with the rear surface of the adjoining product Si
wafer; and a third step of heating the product Si wafers
accommodated within the reaction chamber with a heater arranged
outside the reaction chamber, supplying a process gas into the
reaction chamber from a process gas supply system and exhausting
the process gas from the reaction chamber. In the third step, a
material formed by decomposition of the process gas in a gaseous
layer within the reaction chamber is adsorbed to the rear surfaces
of the product Si wafers and on the Si regions of the product Si
wafers, thereby causing Si-containing films to selectively grow on
the Si regions.
[0092] In the film formation step mentioned above, it is possible
to selectively form silicon-containing films with a flat surface on
the semiconductor regions of a plurality of substrates at one
time.
[0093] More specifically, the oxide film removing step in one
process of a semiconductor device manufacturing method may be
implemented as follows.
[0094] Selective growth can be performed by allowing a chemical
oxide film to grow on the rear surface of a product Si wafer. FIGS.
6A to 6C schematically show an oxide film removal step of removing
an oxide film grown on the rear surface of a product wafer. The
product wafer is subjected to wet cleaning before it is loaded into
a furnace of a hot-wall type vertical low-pressure CVD apparatus.
At this time, the product wafer is cleaned by a unit-wafer-type
cleaning device. The cleaning device performs pre-treatment
cleaning and then DHF cleaning. In general, a spin cleaning method
is employed in which a product wafer is cleaned while spinning the
same.
[0095] The pre-treatment cleaning is performed in the order of SC-1
cleaning (ammonia hydrogen peroxide water cleaning: ammonia
(NH.sub.3)+hydrogen peroxide (H.sub.2O.sub.2)+water (H.sub.2O)) and
SC-2 cleaning (hydrochloric acid hydrogen peroxide water cleaning:
hydrogen chloride (HCl)+hydrogen peroxide (H.sub.2O.sub.2)+water
(H.sub.2O)).
[0096] After the pre-treatment cleaning, only the front surface of
the product wafer is cleaned with DHF (diluted hydrofluoric acid,
HF+H.sub.2O) in the DHF cleaning step to remove the chemical oxide
film. As a result, the chemical oxide film formed on the rear
surface of the product wafer remains intact. At this time,
deionized water continues to be supplied to the rear surface of the
product wafer in order to prevent the DHF from flowing toward the
rear surface. Thus, the chemical oxide film formed on the opposing
surface is kept intact.
[0097] In an alternate embodiment, instead of supplying deionized
water to the rear surface of the product wafer, a shield plate for
completely isolating the rear surface from DHF may be employed so
that DHF cannot reach the rear surface of the product wafer. In
lieu of the spin cleaning method mentioned above, it may be
possible to employ a conveying-type cleaning method in which a
product wafer is conveyed in a horizontal direction during the
cleaning step. In this case, DHF is blown toward the front surface
of the product wafer and deionized water is blown against the rear
surface of the product wafer while conveying the product wafer,
thereby preventing the DHF from reaching the rear surface. For
further details on the conveying cleaning method, reference is made
to Japanese Patent Laid-Open Publication No. 2004-8847.
[0098] As described above, by allowing the chemical oxide film to
remain on the rear surface of the product Si wafer, it is possible
to control a film to selectively grow on the opposing surface of
the product Si wafer. In this case, as compared with the second
method in which the sandwiching dummy wafers are used, the number
of the product Si wafers that can be processed at one time is
increased in proportion to the number of the dummy wafers omitted.
For example, the number of the product Si wafers that can be
conveyed by the boat represents the number of the product Si wafers
that can be processed simultaneously. This significantly increases
the throughput. More specifically, if a boat capable of conveying
100 wafers is used, only 50 product wafers may be processed in the
sandwiching dummy wafer method. In the present method, however, 100
product wafers can be processed at one time.
[0099] In the pre-treatment cleaning performed prior to the DHF
cleaning, it is possible to implement not only the SC-1 cleaning
and the SC-2 cleaning but also ozone (O.sub.3) cleaning or sulfuric
acid hydrogen peroxide water (sulfuric acid
(H.sub.2SO.sub.4)+hydrogen peroxide (H.sub.2O.sub.2)+water
(H.sub.2O)) cleaning.
[0100] Further, the pre-treatment cleaning performed prior to the
DHF cleaning may be employed not only to remove natural oxide films
formed on the wafers or impurities existing within or on the
natural oxide films but also to form chemical oxide films (which is
formed by actively supplying oxide to the wafers and causing a
reaction thereby) in place of the natural oxide films with
uncontrollable thickness property. However, the pre-treatment
cleaning may be omitted if there is no need to remove impurities or
if formation of natural oxide films does not matter.
[0101] (Substrate Cleaning Device)
[0102] In the following, one example of a substrate cleaning device
for implementing the oxide film removal step mentioned above will
be described in detail. This substrate cleaning device is of a
unit-wafer type. A plurality of substrates, the oxide films of
which have been removed by the substrate cleaning device, may be
conveyed to a hot-wall type vertical low-pressure CVD apparatus in
which the substrates are subjected to film formation
processing.
[0103] One embodiment of a substrate cleaning device 10 is shown in
FIG. 7. The substrate cleaning device 10 includes a device body 12
and a cleaning chamber 14 surrounded by the device body 12. A
support unit 18 configured to horizontally support a substrate 16
such as a semiconductor wafer is arranged within the cleaning
chamber 14. The support unit 18 is connected to a rotation
mechanism 20, e.g., a motor, through a rotation shaft 21. The
horizontally supported substrate 16 is rotated by the rotation
mechanism 20.
[0104] The periphery of the support unit 18 is surrounded by a
cover 22. As will be described later, the cover 22 is configured to
receive chemical solutions flying from the substrate 16 when the
substrate 16 is rotated by the support unit 18.
[0105] A first nozzle 28 and a second nozzle 30 are inserted into
the cleaning chamber 14. The first nozzle 28 and the second nozzle
30 are horizontally arranged such that the tip ends thereof extend
to near the center of the substrate 16 supported by the support
unit 18.
[0106] The first nozzle 28 is connected to a first cleaning
solution supply unit 32 configured to supply a cleaning solution
made of, e.g., diluted hydrofluoric acid (DHF), through a control
valve 32a configured to control the supply of the cleaning
solution. The DHF cleaning solution is supplied from the first
nozzle 28 toward the center of the substrate 16.
[0107] The second nozzle 30 is connected to a second cleaning
solution supply unit 34 configured to supply, e.g., an RCA cleaning
solution, through a control valve 34a configured to control the
supply of the RCA cleaning solution. The RCA cleaning solution is
supplied from the second nozzle 30 toward the center of the
substrate 16. The RCA cleaning refers to a cleaning method for
removing foreign materials, organic materials or metallic
contaminants by the combination of cleaning sequences of SC-1 (a
mixed solution of NH.sub.4OH, H.sub.2O.sub.2 and H.sub.2O), SC-2 (a
mixed solution of HCl, H.sub.2O.sub.2 and H.sub.2O), diluted
hydrofluoric acid (DHF) and SPM (a mixed solution of
H.sub.2SO.sub.4 and H.sub.2O.sub.2).
[0108] One ends of a first water supply unit 40 and a second water
supply unit 41 are connected to the first nozzle 28 and the second
nozzle 30, respectively, and the other ends thereof are connected
to a first deionized water supply unit 42 and a second deionized
water supply unit 36, respectively. The first water supply unit 40
and the second water supply unit 41 are configured to supply
deionized water to the inner surface of the cover 22 through the
first nozzle 28 and the second nozzle 30, respectively. Control
valves 42a and 46a configured to control the supply of deionized
water are provided in the first water supply unit 40 and the second
water supply unit 41, respectively.
[0109] One or more third nozzles 54 are provided to be inserted
into the cleaning chamber 14. The third nozzles 54 are obliquely
inserted into the cover 22 through the bottom portion of the device
body 12 and the bottom wall of the cover 22 such that the tip ends
thereof extend to near openings 18a defined in the bottom wall of
the support unit 18. The third nozzles 54 are connected to a third
deionized water supply unit 55 through a control valve 55a
configured to control the supply of deionized water. Deionized
water is supplied from the third nozzles 54 toward the rear surface
of the substrate 16 through the openings 18a defined in the bottom
wall of the support unit 18.
[0110] A drain pipe 44, through which the deionized water supplied
to the cover 22 is drained, is connected to the bottom wall of the
cover 22. The drain pipe 44 extends to the outside of the device
body 12 so that the deionized water existing within the cover 22
can be drained through the drain pipe 44.
[0111] One end of a drying gas supply pipe 46 is connected to the
top portion of the device body 12. A drying gas supply unit 48 is
connected to the other end of the drying gas supply pipe 46. A
control valve 48a configured to control the supply of a drying gas
is provided in the drying gas supply pipe 46. For example, a
nitrogen (N.sub.2) gas is used as the drying gas. An exhaust pipe
50, through which the drying gas is exhausted, is connected to the
bottom portion of the device body 12.
[0112] A controller 52 is configured by a computer and is
configured to control the rotation of the support unit 18 driven by
the rotation mechanism 20, the supply of the DHF cleaning solution
through the first nozzle 28 under the control of the control valve
32a, the supply of the RCA cleaning solution through the second
nozzle 30 under the control of the control valve 34a, the supply of
the deionized water from the first water supply unit 40 and the
second water supply unit 41 under the control of the control valves
42a and 36a, the supply of the deionized water from the third
nozzles 54 under the control of the control valve 55a, and the
supply of the nitrogen (N.sub.2) gas from the drying gas supply
pipe 46 under the control of the control valve 48a.
[0113] (Unit Wafer Cleaning Method)
[0114] Next, a unit wafer cleaning method for cleaning a substrate
and removing an oxide film through the use of the aforementioned
substrate cleaning device 10, as one process of a semiconductor
device manufacturing method, will be described with reference to
FIG. 6.
[0115] First, a single substrate 16 is conveyed into the cleaning
chamber 14 and is prepared on the support unit 18. The rotation of
the substrate 16 is performed by rotating the support unit 18,
which is driven by the rotation mechanism 20 through the rotation
shaft 21. During rotation of the substrate 16, the RCA cleaning
solution is supplied from the second nozzle 30 toward the center of
the substrate 16. The front and rear surfaces of the substrate 16
are cleaned to remove the natural oxide films 160 formed on the
front and rear surfaces of the substrate 16 (see FIG. 6A). At this
time, the RCA cleaning solution flows around the substrate 16 to
reach the rear surface as well, consequently removing the natural
oxide film 160 formed on the rear surface. In the cleaning method
employing the RCA cleaning solution, silicon oxide (SiO.sub.2)
films are formed by hydrogen peroxide (H.sub.2O.sub.2). Thus,
chemical oxide films 168 of about 10 .ANG. in thickness are formed
on the front and rear surfaces of the substrate 16 upon completion
of the above operation (see FIG. 6B).
[0116] While the substrate 16 is being rotated, the control valve
34a is closed to stop the supply of the RCA cleaning solution from
the second nozzle 30, and the control valve 36a is opened to supply
the deionized water as rinsing water from the second nozzle 30
toward the center of the substrate 16, thereby washing away the RCA
cleaning solution remaining on the surfaces of the substrate 16.
The deionized water supplied to the inner surface of the cover 22
is drained to the outside through the drain pipe 44 together with
the residual solution.
[0117] Subsequently, while the substrate 16 is being rotated, the
DHF cleaning solution is supplied from the first nozzle 28 toward
the center of the front surface of the substrate 16 and,
concurrently, the deionized water is supplied from the third
nozzles 54 to the rear surface of the substrate 16, thereby
removing the chemical oxide film 168 formed on the semiconductor
region of the front surface while keeping intact the chemical oxide
film 168 formed on the rear surface (see FIG. 6C).
[0118] Further, while the substrate 16 is being rotated, the
control valve 32a is closed to stop the supply of the DHF cleaning
solution from the first nozzle 28, and the control valve 42a is
opened to supply the deionized water as rinsing water toward the
center of the substrate 16 through the first nozzle 28, thereby
washing away the DHF cleaning solution remaining on the surfaces of
the substrate 16. The deionized water supplied to the inner surface
of the cover 22 is drained to the outside through the drain pipe 44
together with the residual solution.
[0119] The N.sub.2 gas as the drying gas is supplied from the
drying gas supply unit 48 into the cleaning chamber 14 through the
drying gas supply pipe 46 to keep the cleaning chamber 14 in a
N.sub.2 atmosphere. The substrate 16 is dried in the N.sub.2
atmosphere. Then, the rotation of the support unit 18 caused by the
rotation mechanism 20 is stopped. The N.sub.2 gas existing in the
cleaning chamber 14 is exhausted through the exhaust pipe 50.
[0120] Finally, the substrate 16 is taken out from the cleaning
chamber 14 and then conveyed to the afore-mentioned hot-wall type
vertical low-pressure CVD apparatus in which the substrate 16 is
subjected to such processing as selective growth of an epitaxial
film thereon.
Other Embodiments
[0121] In some other embodiment, the present disclosure may be
modified in many different forms without departing from the scope
thereof. While the substrate processing apparatus described in the
foregoing embodiments is a hot-wall type vertical low-pressure CVD
apparatus, namely a batch type vertical low-pressure CVD apparatus
capable of processing a plurality of substrates at one time, the
present disclosure is applicable to a unit-wafer-type substrate
processing apparatus.
[0122] FIG. 8 is a schematic explanation view showing a reaction
furnace of a unit-wafer-type (two-wafer-type) substrate processing
apparatus.
[0123] As shown in FIG. 8, a reaction tube 203 (used as a reaction
furnace) made of quartz, silicon carbide or alumina includes a
horizontally-extending flat space, i.e., a reaction chamber, for
accommodating semiconductor wafers 200 (used as substrates)
therein. A wafer support table 217 (used as a substrate holder)
configured to support the semiconductor wafers 200 is provided
within the reaction tube 203. A gas introduction flange 209 (used
as a manifold) is air-tightly attached to the reaction tube 203. A
conveying chamber (not shown) is connected to the gas introduction
flange 209 through a gate valve 244 (used as a partitioning valve).
A gas introduction line 232 (used as a gas supply pipe) is
connected to the gas introduction flange 209. An exhaust line 231
(used as an exhaust pipe) is connected to a back flange 210. A
pressure control unit 242 configured to control the internal
pressure of the reaction tube 203 at a specified pressure is
provided in the exhaust line 231. A turbo-molecular pump 233 is
connected to the exhaust line 231. The inside of the reaction tube
203 is kept at a high vacuum pressure by the turbo-molecular pump
233. A flow rate control unit 241 configured to control the flow
rate of a gas introduced into the reaction tube 203 is provided in
the gas introduction line 232.
[0124] Since the reaction furnace is of a hot-wall type, an upper
heater 207a and a lower heater 207b, both of which compose a
heating unit, are provided above and below the reaction tube 203.
The upper heater 207a and the lower heater 207b are configured to
heat the inside of the reaction tube 203 either uniformly or with a
temperature gradient. A temperature control unit 247 configured to
control the temperatures of the upper heater 207a and the lower
heater 207b is connected to upper heater 207a and the lower heater
207b. A heat insulation material 208 (used as a heat insulation
member) is provided to cover the upper heater 207a, the lower
heater 207b and the reaction tube 203. The internal temperature of
the reaction tube 203, the flow rate of a gas supplied into the
reaction tube 203 and the internal pressure of the reaction tube
203 are controlled at specified temperature, flow rate and
pressure, respectively, by the temperature control unit 247, the
flow rate control unit 241 and a pressure control unit 242, all of
which are controlled by a controller 249.
[0125] The method of forming a silicon (Si)-containing film through
the use of the unit-wafer-type hot-wall reaction furnace is
essentially the same as the method of forming silicon
(Si)-containing films with the reaction furnace of the hot-wall
type vertical low-pressure CVD apparatus. Therefore, no description
will be made in that regard.
[0126] Hereinafter, some aspects of the present disclosure will be
additionally stated.
[0127] A first aspect of the present disclosure provides a method
of manufacturing a semiconductor device, including: a first step of
conveying a first substrate provided with an opposing surface
having insulator regions and a semiconductor region exposed between
the insulator regions and a second substrate provided with an
insulator surface exposed toward the opposing surface of the first
substrate, into a process chamber in a state that the second
substrate is arranged in a face-to-face relationship with the
opposing surface of the first substrate; and a second step of
selectively forming a silicon-containing film with a flat surface
at least on the semiconductor region of the opposing surface of the
first substrate by heating an inside of the process chamber and
supplying at least a silicon-containing gas and a
chlorine-containing gas into the process chamber.
[0128] The second substrate may be configured such that a
semiconductor region is exposed between insulator regions on the
opposite surface of the second substrate from the opposing surface
of the first substrate, and the second step may include selectively
forming a silicon-containing film with a flat surface on the
semiconductor region of the opposite surface of the second
substrate.
[0129] The silicon-containing gas may be at least one type of gas
selected from the group consisting of a silane gas, a disilane gas
and a dichlorosilane gas, and the chlorine-containing gas may be at
least one type of gas selected from the group consisting of a
chlorine gas and a hydrogen chloride gas.
[0130] The insulator regions of the first substrate and the
insulator surface of the second substrate may be made of silicon
oxide or silicon nitride, and the semiconductor region of the first
substrate may be made of silicon.
[0131] The insulator regions may be substantially flush with the
semiconductor region.
[0132] The second step may include causing a material formed by
decomposition of the silicon-containing gas and the
chlorine-containing gas in a gaseous layer within the process
chamber to be adsorbed to at least a rear surface of the second
substrate and the semiconductor region of the first substrate.
[0133] A second aspect of the present disclosure provides a method
of manufacturing a semiconductor device, including: providing a
plurality of substrates each provided with a front surface and a
rear surface, the front surface having insulator regions and a
semiconductor region arranged between the insulator regions, at
least the semiconductor region of the front surface being covered
with an oxide film, the rear surface being covered with an oxide
film; removing the oxide film formed on the semiconductor region of
the front surface while keeping intact the oxide film formed on the
rear surface; conveying the substrates, in which the oxide film
formed on the semiconductor region is removed with the oxide film
formed on the rear surface remaining intact, into a process chamber
in a state that the substrates are stacked one above another at a
predetermined interval; and selectively forming a
silicon-containing film on the semiconductor region of each of the
substrates by heating the process chamber and supplying at least a
silicon-containing gas and a chlorine-containing gas into the
process chamber.
[0134] The selectively forming the silicon-containing film may
include selectively forming a silicon-containing film with a flat
surface on the semiconductor region of each of the substrates.
[0135] The silicon-containing gas may be at least one type of gas
selected from the group consisting of a silane gas, a disilane gas
and a dichlorosilane gas, and the chlorine-containing gas may be at
least one type of gas selected from the group consisting of a
chlorine gas and a hydrogen chloride gas.
[0136] The insulator regions may be made of silicon oxide or
silicon nitride, and the semiconductor region may be made of
silicon.
[0137] The insulator regions may be substantially flush with the
semiconductor region.
[0138] The removing the oxide film may include supplying water to
the rear surface of each of the substrates while supplying a
hydrofluoric-acid-containing material to the front surface of each
of the substrates, to remove the oxide film formed on the
semiconductor region of the front surface while keeping intact the
oxide film formed on the rear surface.
[0139] A third aspect of the present disclosure provides a
substrate processing apparatus, including: a process chamber
configured to accommodate and process a first substrate provided
with an opposing surface having insulator regions and a
semiconductor region exposed between the insulator regions and a
second substrate provided with an insulator surface exposed toward
the opposing surface of the first substrate; a first gas supply
system configured to supply a silicon-containing gas into the
process chamber; a second gas supply system configured to supply a
chlorine-containing gas into the process chamber; a heater
configured to heat the first substrate and the second substrate;
and a controller configured to control the heater, the first gas
supply system and the second gas supply system such that the
silicon-containing gas and the chlorine-containing gas are supplied
between the first substrate and the second substrate arranged in a
face-to-face relationship with the opposing surface of the first
substrate, to selectively form a silicon-containing film with a
flat surface at least on the semiconductor region of the first
substrate.
[0140] A fourth aspect of the present disclosure provides a method
including: conveying a substrate holder configured to hold a
plurality of substrates staked one above another at a predetermined
interval, into a process chamber, each of the substrates provided
with a front surface and a rear surface, the front surface having
insulator regions and a semiconductor region exposed between the
insulator regions, the rear surface exposing an insulator surface;
and forming a silicon-containing film on the semiconductor region
of each of the substrates by heating the process chamber and
supplying at least a silicon-containing gas and a
chlorine-containing gas into the process chamber.
[0141] A fifth aspect of the present disclosure provides a method
including: providing a first substrate having a semiconductor
region exposed between insulator regions and a second substrate
having an insulator surface opposing the first substrate; and
supplying at least a silicon-containing gas and a
chlorine-containing gas into at least the first substrate and the
second substrate, thereby selectively forming a silicon-containing
film with a flat surface on at least the semiconductor region of
the first substrate.
[0142] According to the present disclosure, it is possible to
selectively form a silicon-containing film with a flat surface on a
semiconductor region of a substrate in a reliable manner.
[0143] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the disclosures. Indeed, the novel
methods and apparatuses described herein may be embodied in a
variety of other forms; furthermore, various omissions,
substitutions and changes in the form of the embodiments described
herein may be made without departing from the spirit of the
disclosures. The accompanying claims and their equivalents are
intended to cover such forms or modifications as would fall within
the scope and spirit of the disclosures.
* * * * *