U.S. patent application number 12/536061 was filed with the patent office on 2010-02-11 for substrate processing apparatus and method of manufacturing semiconductor device.
This patent application is currently assigned to Hitachi-Kokusai Electric, Inc.. Invention is credited to Masanao Fukuda, Takafumi Sasaki, Kazuhiro Yuasa.
Application Number | 20100035440 12/536061 |
Document ID | / |
Family ID | 41653342 |
Filed Date | 2010-02-11 |
United States Patent
Application |
20100035440 |
Kind Code |
A1 |
Fukuda; Masanao ; et
al. |
February 11, 2010 |
SUBSTRATE PROCESSING APPARATUS AND METHOD OF MANUFACTURING
SEMICONDUCTOR DEVICE
Abstract
A substrate processing apparatus includes: a reaction tube
configured to process a plurality of substrates; a heater
configured to heat the inside of the reaction tube; a holder
configured to arrange and hold the plurality of substrates within
the reaction tube; a first nozzle disposed in an area corresponding
to a substrate arrangement area where the plurality of substrates
are arranged, and configured to supply hydrogen-containing gas from
a plurality of locations of the area into the reaction tube; a
second nozzle disposed in the area corresponding to the substrate
arrangement area, and configured to supply oxygen-containing gas
from a plurality of locations of the area into the reaction tube;
an exhaust outlet configured to exhaust the inside of the reaction
tube; and a pressure controller configured to control pressure
inside the reaction tube to be lower than atmospheric pressure,
wherein the first nozzle is provided with a plurality of first gas
ejection holes, and the second nozzle is provided with as many
second gas ejection holes as at least the plurality of substrates
so that the second gas ejection holes correspond to at least the
respective substrates.
Inventors: |
Fukuda; Masanao;
(Toyama-shi, JP) ; Sasaki; Takafumi; (Toyama-city,
JP) ; Yuasa; Kazuhiro; (Jakacka-city, JP) |
Correspondence
Address: |
BRUNDIDGE & STANGER, P.C.
1700 DIAGONAL ROAD, SUITE 330
ALEXANDRIA
VA
22314
US
|
Assignee: |
Hitachi-Kokusai Electric,
Inc.
|
Family ID: |
41653342 |
Appl. No.: |
12/536061 |
Filed: |
August 5, 2009 |
Current U.S.
Class: |
438/765 ;
118/724; 257/E21.485 |
Current CPC
Class: |
C23C 16/45546 20130101;
C23C 16/4583 20130101; C23C 16/45578 20130101; H01L 21/02238
20130101; H01L 21/31662 20130101; C23C 16/52 20130101; H01L
21/02255 20130101; C23C 16/40 20130101; C23C 16/45519 20130101;
C23C 16/401 20130101; C23C 16/45548 20130101 |
Class at
Publication: |
438/765 ;
118/724; 257/E21.485 |
International
Class: |
H01L 21/465 20060101
H01L021/465 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 6, 2008 |
JP |
2008-203187 |
Jun 9, 2009 |
JP |
2009-138577 |
Claims
1. A substrate processing apparatus comprising: a reaction tube
configured to process a plurality of substrates; a heater
configured to heat the inside of the reaction tube; a holder
configured to arrange and hold the plurality of substrates within
the reaction tube; a first nozzle disposed in an area corresponding
to a substrate arrangement area where the plurality of substrates
are arranged, and configured to supply hydrogen-containing gas from
a plurality of locations of the area into the reaction tube; a
second nozzle disposed in the area corresponding to the substrate
arrangement area, and configured to supply oxygen-containing gas
from a plurality of locations of the area into the reaction tube;
an exhaust outlet configured to exhaust the inside of the reaction
tube; and a pressure controller configured to control pressure
inside the reaction tube to be lower than atmospheric pressure,
wherein the first nozzle is provided with a plurality of first gas
ejection holes, and the second nozzle is provided with as many
second gas ejection holes as at least the plurality of substrates
so that the second gas ejection holes correspond to at least the
respective substrates.
2. The substrate processing apparatus according to claim 1, wherein
the second gas ejection holes are configured to eject
oxygen-containing gas to the respective substrates at a uniform
flow rate.
3. The substrate processing apparatus according to claim 1, wherein
the respective second gas ejection holes and the respective
substrates corresponding to the second gas ejection holes are
configured at regular distances in a substrate arrangement
direction.
4. The substrate processing apparatus according to claim 1, wherein
an arrangement pitch of the second gas ejection holes is equal to
an arrangement pitch of the substrates.
5. The substrate processing apparatus according to claim 1, wherein
the number of the first gas ejection holes is smaller than the
number of the second gas ejection holes.
6. The substrate processing apparatus according to claim 1, wherein
the first gas ejection holes are installed as many as at least the
plurality of substrates so that the first gas ejection holes are in
1:1 correspondence with the plurality of substrates.
7. The substrate processing apparatus according to claim 6, wherein
an arrangement pitch of the first gas ejection holes is equal to an
arrangement pitch of the substrates.
8. The substrate processing apparatus according to claim 6, wherein
the respective first gas ejection holes and the respective
substrates corresponding to the first gas ejection holes are
configured at regular distances in a substrate arrangement
direction.
9. The substrate processing apparatus according to claim 6, wherein
the number of the first gas ejection holes is equal to the number
of the second gas ejection holes.
10. The substrate processing apparatus according to claim 6,
wherein the first gas ejection holes are in 1:1 correspondence with
the second gas ejection holes.
11. A method of manufacturing a semiconductor device, comprising:
loading a plurality of substrates into a reaction tube; processing
the plurality of substrates by supplying hydrogen-containing gas
and oxygen-containing gas into the reaction tube, which is in a
heated state, with pressure inside the reaction tube being lower
than atmospheric pressure, respectively through a first nozzle and
a second nozzle disposed in an area corresponding to a substrate
arrangement area where the plurality of substrates are arranged;
and unloading the plurality of processed substrates from the
reaction tube, wherein when the substrates are processed, the
hydrogen-containing gas is supplied into the reaction tube from a
plurality of locations of the area corresponding to the substrate
arrangement area through a plurality of first gas ejection holes
installed in the first nozzle and, at the same time, the
oxygen-containing gas is supplied into the reaction tube from a
plurality of locations of the area corresponding to the substrate
arrangement area through second gas ejection holes installed as
many as at least the plurality of substrates in the second nozzle
so that the second gas ejection holes are in 1:1 correspondence
with at least the plurality of substrates.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATION
[0001] This U.S. non-provisional patent application claims priority
under 35 U.S.C. .sctn.119 of Japanese Patent Application Nos.
2008-203187, filed on Aug. 6, 2008, and 2009-138577, filed on Jun.
9, 2009, in the Japanese Patent Office, the entire contents of
which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a substrate processing
apparatus for processing a substrate, and a method of manufacturing
a semiconductor device which includes a process of processing a
substrate by using the substrate processing apparatus, and more
particularly, to an oxidation apparatus for oxidizing the surface
of a substrate, and a method of manufacturing a semiconductor
device, such as IC, which includes a process of oxidizing a
substrate by using the oxidation apparatus.
[0004] 2. Description of the Prior Art
[0005] FIG. 1 is an overall view of an apparatus for manufacturing
a semiconductor device (semiconductor manufacturing apparatus) as a
conventional substrate processing apparatus. The conventional
apparatus is configured by a cassette stocker 1' that mounts a
wafer cassette, a boat 3', a wafer transfer unit (transfer device)
that transfers a wafer between the wafer cassette mounted on the
cassette stocker 1' and the boat 3', a boat elevating unit (boat
elevator) 4' that loads the boat 3' into a heat-treating furnace
and unloads the boat 3' from the heat-treating furnace, and the
heat-treating furnace 5' provided with a heating unit (heater).
[0006] To explain the prior art, the heat-treating furnace 5' of
the semiconductor manufacturing apparatus having the configuration
of FIG. 2 is exemplified. The apparatus shown in FIG. 1 includes
the boat 3' that holds about 100 to 150 sheets of stacked wafers
6', main nozzles 7', sub-nozzles 8' arranged in multiple stages, a
heater 9', a reaction tube 10', and a gas exhaust outlet 11'. A gas
supply unit configured by the main nozzles 7', as shown in FIG. 3,
may be configured in a form of a shower plate 12'. This apparatus
forms a silicon oxide film as an oxide film on a wafer 6', such as
a silicon wafer, by supplying from the main nozzles 7' O.sub.2 gas
at a flow rate of several thousands of sccm and H.sub.2 gas at a
flow rate lower than O.sub.2 gas, for example, several hundreds of
sccm, at a temperature of about 850 to 950.degree. C. and under a
low pressure environment of about 0.5 Torr (67 Pa) and also by
assistantly supplying H.sub.2 gas at a relatively low flow rate
from the sub-nozzles 8' at the same time so as to form a film
uniformly over the entire stacked wafers.
[0007] It is known that the growth of the oxide film requires
O.sub.2, but the growth rate of the oxide film is extremely low in
a source gas of an O.sub.2 single body under a low pressure
environment of about 50 Pa. Hence, the growth rate of the oxide
film gets faster when H.sub.2 gas is added (for example, see Patent
Document 1). Also, the oxide film is not formed in an H.sub.2
single body. That is, when seen as a whole, the growth of the oxide
film depends on concentrations (flow rates or partial pressures) of
both O.sub.2 and H.sub.2.
[Prior Art Document]
[Patent Document]
[0008] [Patent Document 1] Pamphlet of International Publication
No. WO2005/020309
[0009] The most characteristic film thickness distribution in the
conventional apparatus is shown in FIG. 4. This is a film thickness
distribution of an oxide film formed on a wafer when O.sub.2 gas of
several thousands of sccm and H.sub.2 gas of several hundreds of
sccm are supplied as source gases from the main nozzles 7' only in
the above-described pressure and temperature zones. According to
the graph of FIG. 4, the film thickness of the oxide film formed on
the wafer becomes thinner over from the top to the bottom. As
described in the specification of Japanese Patent Application No.
2008-133772, filed by the present applicant, atomic oxygen O that
is an intermediate product contributes to the growth of the oxide
film. O.sub.2 gas and H.sub.2 gas supplied from the main nozzles 7'
temporarily reach a state close to a chemical equilibrium in the
top area, and then, show a behavior that flows between the
periphery of a wafer and the inner wall of a reaction tube, while a
mole fraction of each intermediate product is constantly
maintained. At this time, since a mixed gas of the source gas and
the intermediate product comes under a flow resistance, the density
of the mixed gas at the top is high and the density of the mixed
gas at the bottom is low. Accordingly, the mole density of the
atomic oxygen O changes at the top and the bottom, causing the
difference in the film thickness of the oxide film formed on the
wafer at the top and the bottom. Also, since the atomic oxygen O is
consumed when the oxide film is grown on the wafer, the atomic
oxygen O is insufficient over from the top and the bottom, and
therefore, the difference of the film thickness is caused as shown
in FIG. 4. Such a phenomenon is called a loading effect, and it
equally occurs even in the construction having a shower plate 12'
as shown in FIG. 3. In the conventional construction, in order to
eliminate the loading effect, the sub-nozzles 8' for H.sub.2 gas
supply are arranged in multiple stages (in the cases of FIG. 2 and
FIG. 3, four stages), and mass flow controllers configured to
individually control the respective sub-nozzles 8' are intervened
to supply an appropriate amount of H.sub.2 gas, thereby correcting
the film thickness uniformity between wafer surfaces.
[0010] It is known that integrated circuit (IC) patterns are formed
on the wafer so as to manufacture IC, but a gas flow rate (amount
of atomic oxygen O) for growing an oxide film with the same film
thickness on the wafer is different depending on the circuit
patterns. If consideration is given based on the case of forming an
oxide film on a bare wafer, in particularly, in the case of a wafer
with deep recessed patterns such as shallow trench isolation (STI)
or the like as shown in FIG. 5, since the exposed surface area of
Si is dozens of times the surface area of the bare wafer, a large
amount of the source gas (atomic oxygen O) is consumed by the film
growth. On the contrary, as shown in FIG. 6, in the case of a wafer
that is partially covered with an oxide film, a gas flow rate
(amount of atomic oxygen O) necessary for the film growth is low
compared to the bare wafer. As such, the consumed amount of the
source gas (atomic oxygen O) necessary for forming the oxide film
with the same film thickness on the wafer is different, depending
on circuit patterns formed on the wafer. Therefore, the flow rate
of H.sub.2 gas supplied from the sub-nozzles 8' for uniformizing
the film thickness of the oxide films formed on the wafers in a
wafer stack direction changes (this is called a "circuit pattern
dependency of the loading effect"). When a wafer consuming a small
amount of a source gas as shown in FIG. 6 is loaded, the film
thickness distribution of an oxide film formed on the wafer is
represented by (a) of FIG. 7. When a bare wafer is loaded, the film
thickness distribution of an oxide film formed on the bare wafer is
represented by (b) of FIG. 7. When a wafer consuming a large amount
of a source gas as shown in FIG. 5 is loaded, the film thickness
distribution of an oxide film formed on the wafer is represented by
(c) of FIG. 7. As such, since the loading effect changes according
to the circuit patterns of the wafer surface, the optimum flow rate
distribution of H.sub.2 gas supplied from the sub-nozzles 8' to
each other is different.
[0011] Regarding the loading effect, by utilizing a tool that
calculates an optimum flow rate of a source gas in order for
uniform film formation, which is described in the specification of
Japanese Patent Application No. 2008-133772, filed by the present
applicant, the optimum flow rate of H.sub.2 gas supplied from the
sub-nozzles 8' is calculated in a requisite minimum (1-2 times)
test film formation, and the inter-wafer film thickness uniformity
of the oxide films formed on the wafers is corrected.
[0012] In the case of the conventional construction, a gas flow
traversing the wafer does not mostly exist, and the film-forming
contribution gas (atomic oxygen O) infiltrates between the wafers
due to a concentration diffusion only directed from the periphery
of the wafer to the central part of the wafer. Thus, there is a
limit in the intra-wafer film thickness uniformity (in most process
wafers, the film thickness has a mortar-shaped intra-wafer film
thickness distribution). Positions of the sub-nozzles experimented
on the bare wafers and a film thickness map of oxide films formed
on the wafers are shown in FIG. 8. According to the film thickness
map, the film thicknesses of the oxide films formed on the wafers
have a center-concave () distribution with uniformity at positions
other than the positions where the sub-nozzles exist as represented
in FIG. 8. It is thought that this is because the consumption of
the atomic oxygen O on the wafer surface at those positions and the
concentration diffusion directed from the periphery of the wafer to
the central part of the wafer are dominant. According to the film
thickness map of FIG. 8, the intra-wafer film thickness uniformity
at the positions where the sub-nozzles do not exist has the
center-concave () distribution. The intra-wafer film thickness
uniformity at the positions where the sub-nozzles exist has a
slightly-lessened center-concave () distribution.
[0013] Regarding this phenomenon, explanation will be given on a
Computational Fluid Dynamics (CFD) analysis (thermo-fluid analysis)
based on an elementary reaction that is carried out at a process
temperature (temperature inside the processing chamber) of
900.degree. C., a process pressure (pressure inside the processing
chamber) of 0.5 Torr, and O.sub.2:H.sub.2=15:1 by using a
two-dimensional axisymmetric calculating area shown in FIG. 9. The
bare wafer was supposed as the process wafer. Also, the CFD
analysis was performed by using a general-purpose thermo-fluid
analysis tool. A detailed explanation of the calculation model is
described in the specification of Japanese Patent Application No.
2008-133772, filed by the present applicant. A normal calculation
result under calculation conditions of FIG. 9 (mole density
distribution of atomic oxygen O at the inside of the processing
chamber) is shown in FIG. 10. According to the O density
distribution shown in FIG. 10, it is determined that the difference
of concentration occurs in a radial direction of the wafer in a
normal state, and the concentration becomes normal in this state.
Since the intra-wafer film thickness distribution of the oxide film
formed on the wafer directly depends on the O concentration, the
difference of the film thickness naturally occurs in the radial
direction of the wafer, and FIG. 10 shows that the intra-wafer film
thickness distributions of the oxide films formed on all wafers
other than the top wafers have the center-concave () (mortar)
distribution.
[0014] FIG. 11 shows an O concentration distribution (mole density
distribution of atomic oxygen O at the inside of the processing
chamber) when H.sub.2 is supplied from the sub-nozzles. Since it is
a two-dimensional axisymmetric system, a three-dimensional nozzle
shape is not correctly reproduced, but it shows a qualitative
result in which a flow caused by a low pressure field of a
diffusion control of about 0.5 Torr is ignored to some extent. The
intra-wafer O concentration distribution of the wafer that has a
center-convex distribution at the positions where H.sub.2 halfway
supply nozzles (sub-nozzles) are added, which are represented by
Nozzle in FIG. 11, and the intra-wafer O concentration distribution
of the wafer that has a center-concave distribution at the
positions where the sub-nozzles do not exist are qualitatively
shown. These calculation result does not completely coincide with
the experimental result, but they well coincide with each other in
the qualitative tendency (center-concave distribution at the
positions where the sub-nozzles do not exist, and reduction of the
center-concave distribution at the positions near the sub-nozzles).
The reason why the calculation result and the experimental result
do not completely coincide with each other is that a surface
reaction that is a complex reaction mechanism in practice is simply
assumed in calculation, and a three-dimensional flow is not
considered in calculation (two-dimensional axisymmetric system
calculation).
[0015] For example, as described above, since the wafer with deep
recessed patterns such as STI shown in FIG. 5 consumes a larger
amount of a source gas (atomic oxygen O) than the bare wafer, the
center-concave distribution of the intra-wafer film thickness
distribution is prominent at the positions where the sub-nozzles do
not exist. That is, in order to obtain a flat intra-wafer film
thickness distribution when processing the wafer with the deep
recessed patterns such as STI, it is preferable that the
intra-wafer film thickness distribution actively becomes the
center-convex () distribution when processing the bare wafer. The
degradation of the intra-wafer film thickness uniformity according
to this phenomenon (center-concave () distribution of the
intra-wafer film thickness distribution) may be avoided by
enlargement of a wafer stack pitch or a low pressurization inside a
reaction chamber during wafer processing. However, the enlargement
of the wafer stack pitch lowers throughput, and the lower
pressurization inside the reaction chamber significantly lowers an
overall oxidation rate.
SUMMARY OF THE INVENTION
[0016] An object of the present invention is to provide a substrate
processing apparatus, which is capable of suppressing the
intra-wafer film thickness distribution from being a center-concave
() distribution, while the inter-wafer film thickness uniformity is
maintained, and improving the intra-wafer film thickness
distribution, and to provide a method of manufacturing a
semiconductor device, which includes a process of processing a
substrate by using the substrate processing apparatus.
[0017] According to an aspect of the present invention, there is
provided a substrate processing apparatus including: a reaction
tube configured to process a plurality of substrates; a heater
configured to heat the inside of the reaction tube; a holder
configured to arrange and hold the plurality of substrates within
the reaction tube; a first nozzle disposed in an area corresponding
to a substrate arrangement area where the plurality of substrates
are arranged, and configured to supply hydrogen-containing gas from
a plurality of locations of the area into the reaction tube; a
second nozzle disposed in the area corresponding to the substrate
arrangement area, and configured to supply oxygen-containing gas
from a plurality of locations of the area into the reaction tube;
an exhaust outlet configured to exhaust the inside of the reaction
tube; and a pressure controller configured to control pressure
inside the reaction tube to be lower than atmospheric pressure,
wherein the first nozzle is provided with a plurality of first gas
ejection holes, and the second nozzle is provided with as many
second gas ejection holes as at least the plurality of substrates
so that the second gas ejection holes correspond to at least the
respective substrates.
[0018] According to another aspect of the present invention, there
is provided a method of manufacturing a semiconductor device,
including: loading a plurality of substrates into a reaction tube;
processing the plurality of substrates by supplying
hydrogen-containing gas and oxygen-containing gas into the reaction
tube, which is in a heated state, with pressure inside the reaction
tube being lower than atmospheric pressure, respectively through a
first nozzle and a second nozzle disposed in an area corresponding
to a substrate arrangement area where the plurality of substrates
are arranged; and unloading the plurality of processed substrates
from the reaction tube, wherein when the substrates are processed,
the hydrogen-containing gas is supplied into the reaction tube from
a plurality of locations of the area corresponding to the substrate
arrangement area through a plurality of first gas ejection holes
installed in the first nozzle and, at the same time, the
oxygen-containing gas is supplied into the reaction tube from a
plurality of locations of the area corresponding to the substrate
arrangement area through second gas ejection holes installed as
many as at least the plurality of substrates in the second nozzle
so that the second gas ejection holes are in 1:1 correspondence
with at least the plurality of substrates.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a perspective view showing an overall
configuration of a semiconductor manufacturing apparatus.
[0020] FIG. 2 is a schematic sectional view showing a configuration
of a heat-treating furnace of the semiconductor manufacturing
apparatus.
[0021] FIG. 3 is a schematic sectional view showing another
configuration of a heat-treating furnace of the semiconductor
manufacturing apparatus.
[0022] FIG. 4 is a graph showing a film thickness distribution when
a loading effect occurs.
[0023] FIG. 5 is a schematic sectional view of a wafer where
patterns such as STI are formed.
[0024] FIG. 6 is a schematic sectional view of a wafer whose
surface is partially covered with an oxide film.
[0025] FIG. 7 is a film thickness distribution map showing pattern
dependency of a loading effect.
[0026] FIG. 8 is a view showing a relationship between a film
thickness map and positions of sub-nozzles.
[0027] FIG. 9 is a view showing a calculation area considered by a
CFD analysis.
[0028] FIG. 10 is a view showing an atomic oxygen concentration
distribution (no gas supply from sub-nozzles) as a result of CFD
analysis.
[0029] FIG. 11 is a view showing an atomic oxygen concentration
distribution (H.sub.2 gas supply from sub-nozzles) as a result of
CFD analysis.
[0030] FIG. 12 is a schematic sectional view showing a
configuration of a heat-treating furnace in accordance with a first
embodiment of the present invention.
[0031] FIG. 13 is a view showing an atomic oxygen concentration
distribution (H.sub.2 gas and O.sub.2 gas supply from sub-nozzles)
as a result of CFD analysis.
[0032] FIG. 14 is an analysis result of an atomic oxygen O
concentration between surfaces of wafers and within surfaces of
wafers, showing inter-wafer uniformity and intra-wafer uniformity
of an atomic oxygen O concentration (H.sub.2 gas and O.sub.2 gas
supply form sub-nozzles).
[0033] FIG. 15 is an analysis result of an atomic oxygen O
concentration between surfaces of wafers and within surfaces of
wafers, showing inter-wafer uniformity and intra-wafer uniformity
of an atomic oxygen O concentration (H.sub.2 gas and O.sub.2 gas
supply from sub-nozzles+increase of H.sub.2 gas ).
[0034] FIG. 16 is a view schematically showing an atomic oxygen O
concentration distribution in the vicinity of H.sub.2 gas and
O.sub.2 gas supply points of sub-nozzles.
[0035] FIGS. 17A, FIG. 17B, FIG. 17C, and FIG. 17D are views
schematically showing atomic oxygen O mole concentration on wafer
surfaces and film thickness cross-section maps.
[0036] FIG. 18 is a schematic sectional view showing a
configuration of a heat-treating furnace in accordance with a
second embodiment of the present invention.
[0037] FIG. 19 is a view showing an experimental result of an
intra-wafer film thickness uniformity when an oxidation process is
performed in such a state that an arrangement pitch of O.sub.2 gas
supply points is larger than an arrangement pitch of wafers
(O.sub.2 gas supply points are formed at seven locations).
[0038] FIG. 20 is a schematic sectional view showing a
configuration of a heat-treating furnace in accordance with a third
embodiment of the present invention.
[0039] FIG. 21 is a view schematically showing an atomic oxygen O
concentration distribution in the vicinity of O.sub.2 gas supply
points of sub-nozzles when an arrangement pitch of O.sub.2 gas
supply points is larger than an arrangement pitch of wafers.
[0040] FIG. 22 is a view schematically showing an atomic oxygen O
concentration distribution in the vicinity of O.sub.2 gas supply
points of sub-nozzles when as many O.sub.2 gas supply points as
wafers are installed such that they correspond to a plurality of
wafers, respectively.
[0041] FIG. 23 is a view showing an experimental result of an
intra-wafer film thickness uniformity when as many O.sub.2 gas
supply points as wafers are installed such that they correspond to
a plurality of wafers, respectively.
[0042] FIG. 24 is a schematic sectional view showing a
configuration of a heat-treating furnace in accordance with a
fourth embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0043] The inventors found that when O.sub.2 gas as well as H.sub.2
gas was supplied from sub-nozzles installed in an inner side of a
reaction tube, that is, O.sub.2 gas as well as H.sub.2 gas was
supplied from a plurality of locations of an area corresponding to
a wafer arrangement area where a plurality of sheets of wafers were
arranged, a reaction was controlled so that atomic oxygen O is
generated much more at a wafer central part while an atomic oxygen
O concentration was suppressed from increasing at a wafer edge
part, whereby a prominent center-concave () distribution of an
intra-wafer film thickness distribution (degradation of intra-wafer
uniformity) could be prevented in a patterned wafer. Hereinafter, a
first embodiment will be described with reference to drawings.
First Embodiment
[0044] As a substrate processing apparatus in accordance with a
first embodiment of the present invention, a batch-type vertical
semiconductor manufacturing apparatus (oxidation apparatus) will be
described with reference to FIG. 12. FIG. 12 is a schematic
sectional view showing a configuration example of a heat-treating
furnace (oxidation furnace) relevant to the first embodiment of the
present invention. In FIG. 12, an apparatus configuration example
of a heat-treating furnace 5 of a substrate processing apparatus
whose maximum loading capacity is for example 120 sheets of
wafers.
[0045] As shown in FIG. 12, the heat-treating furnace 5 of the
substrate processing apparatus relevant to this embodiment includes
a resistance heater 9 as a heat source. The heater 9 is
cylindrically-shaped and is supported on a heater base (not shown)
used as a holding plate so that the heater 9 is vertically
installed. At the inside of the heater 9, a reaction tube 4 is
installed concentrically with the heater 9. A processing chamber
(reaction chamber) 4 that processes a substrate is formed inside
the reaction tube 10, and the reaction tube 10 is configured such
that a boat 3 used as a substrate holding tool is loaded. The boat
3 is configured to hold wafers 8 such as silicon wafers as a
plurality of sheets of substrates in multiple stages in an
approximately horizontal state at gaps (substrate pitch distances).
In the following description, a wafer support position of an
uppermost stage inside the boat 3 is represented by #120, and a
wafer support position of a lowermost stage is represented by #1.
In addition, a wafer 6 held at a support position of an n-th stage
from the lowermost stage inside the boat 3 is represented by a
wafer #n.
[0046] A lower portion of the reaction tube 10 is opened so that
the boat 3 is inserted thereinto. The opening of the reaction tube
10 is tightly closed with a seal cap 13. On the seal cap 13, a heat
insulation cap 12 that supports the boat 3 from the lower side is
installed. The heat insulation cap 12 is installed in a rotation
mechanism 14 through a rotation shaft (not shown) installed to
penetrate the seal cap 13. The rotation mechanism 14 is configured
to rotate the heat insulation cap 12 and the boat 3 through the
rotation shaft so that the wafer 6 supported on the boat 3 is
rotated.
[0047] A shower plate 12 is installed on a ceiling wall of the
reaction tube 10, and a buffer chamber 12a as a mixing space is
formed by the ceiling wall of the reaction tube 10 and the shower
plate 12. Above the reaction tube 10, an oxygen supply nozzle 7a
that supplies oxygen (O.sub.2) gas as oxygen-containing gas from
the upper side of the processing chamber 4 to wafers 6, and a
hydrogen supply nozzle 7b that supplies hydrogen (H.sub.2) gas as
hydrogen-containing gas from the upper side of the processing
chamber 4 to wafers 6 are connected to communicate with the inside
of the buffer chamber 12a. A gas jet orifice of the oxygen supply
nozzle 7a is directed downward and configured to jet oxygen gas
downward from the upper side of the processing chamber 4 (along a
wafer stack direction). A gas jet orifice of the hydrogen supply
nozzle 7b is directed downward and configured to jet hydrogen gas
downward from the upper side of the processing chamber 4 (along a
wafer stack direction). O.sub.2 gas supplied from the oxygen supply
nozzle 7a and H.sub.2 gas supplied from the hydrogen supply nozzle
7b are mixed inside the buffer chamber 12a and then supplied into
the processing chamber 4 through the shower plate 12. A main nozzle
7 is configured by the oxygen supply nozzle 7a and the hydrogen
supply nozzle 7b. In addition, the shower plate 12 is provided with
gas supply ports that supply O.sub.2 gas and H.sub.2 gas in a
shower manner from one end toward the other end of a wafer
arrangement area where a plurality of sheets of wafers 6 are
arranged.
[0048] An oxygen supply pipe 70a as an oxygen gas supply line is
connected to the oxygen supply nozzle 7a. At the oxygen supply pipe
70a, an oxygen gas supply source (not shown), an open-close valve
93a, a mass flow controller (MFC) 92a as a flow rate control unit
(flow rate controller), and an open-close valve 91a are installed
sequentially from a upstream side. In addition, a hydrogen supply
pipe 70b as a hydrogen gas supply line is connected to the hydrogen
supply nozzle 7b. At the hydrogen supply pipe 70b, a hydrogen gas
supply source (not shown), an open-close valve 93b, a mass flow
controller (MFC) 92b as a flow rate control unit (flow rate
controller), and an open-close valve 91b are installed sequentially
from the upstream side.
[0049] A hydrogen supply nozzle 8b through which H.sub.2 gas as
hydrogen-containing gas is supplied from the side of the inside of
the processing chamber 4 to the wafers 6 is connected to the side
lower part of the reaction tube 10, while penetrating the sidewall
of the reaction tube 10. The hydrogen supply nozzle 8b is disposed
in a area corresponding to the wafer arrangement area, that is, a
cylindrical area surrounding the wafer arrangement area with facing
the wafer arrangement area at the inside of the reaction tube 10.
The hydrogen supply nozzle 8b is configured by a plurality of (in
this embodiment, four) L-shaped nozzles each having a different
length and extending upward along the inner wall of the sidewall of
the reaction tube 10. Since the plurality of nozzles constituting
the hydrogen supply nozzle 8b have different lengths in the wafer
arrangement direction, H.sub.2 gas is supplied into the reaction
tube 10 from a plurality of (in this embodiment, seven) locations
of the area corresponding to the wafer arrangement area, and a
hydrogen concentration inside the reaction chamber 4 in the wafer
arrangement direction (vertical direction) is adjusted. The
hydrogen supply nozzle 8b is installed along the inner wall nearer
the inner wall of the sidewall of the reaction tube 10 than the
wafers 6. A hydrogen sub-nozzle is configured by the hydrogen
supply nozzle 8b. In addition, a first nozzle is configured by the
hydrogen supply nozzle 8b.
[0050] Top surfaces of tips of the plurality of nozzles
constituting the hydrogen supply nozzle 8b are closed, and at least
one gas ejection hole is installed in a side surface of the tip
portion of each nozzle. In FIG. 12, arrows extending from the
hydrogen supply nozzle 8b toward the wafers 6 represent H.sub.2 gas
ejection directions from the respective gas ejection holes, and
root parts of the arrows represent the respective gas ejection
holes. That is, the gas ejection hole is directed toward the wafer
and is configured to eject H.sub.2 gas from the side inside the
processing chamber 4 toward the wafer 6 in a horizontal direction
(direction along a principal surface of the wafer). In the case of
this embodiment, each of the longest nozzle, the second longest
nozzle and the third longest nozzle is provided with two gas
ejection holes, and the shortest nozzle is provided with one gas
ejection hole. The plurality of (in this embodiment, seven) gas
ejection holes are installed at regular intervals. The lower gas
ejection hole of the longest nozzle is installed at an intermediate
position between the upper gas ejection hole of the longest nozzle
and the upper gas ejection hole of the second longest nozzle. In
addition, the lower gas ejection hole of the second longest nozzle
is installed at an intermediate position between the upper gas
ejection hole of the second longest nozzle and the upper gas
ejection hole of the third longest nozzle. In addition, the lower
gas ejection hole of the third longest nozzle is installed at an
intermediate position between the upper gas ejection hole of the
third longest nozzle and the gas ejection hole of the shortest
nozzle. These installations of the gas ejection holes make it
possible to supply H.sub.2 gas that is finely adjusted in the wafer
arrangement direction, and thus, the hydrogen concentration can be
finely adjusted. A first gas ejection hole is configured by these
gas ejection holes.
[0051] A hydrogen supply pipe 80b as a hydrogen gas supply line is
connected to the hydrogen supply nozzle 8b. The hydrogen supply
pipe 80b is configured by a plurality of (in this embodiment, four)
pipes that are connected to the plurality of nozzles constituting
the hydrogen supply nozzle 8b, respectively. At the hydrogen supply
pipe 80b, a hydrogen gas supply source (not shown), an open-close
valve 96b, a mass flow controller (MFC) 95b as a flow rate control
unit (flow rate controller), and an open-close valve 94b are
installed sequentially from a upstream side. The open-close valve
96b, the mass flow controller 95b, and the open-close valve 94b are
installed in the respective pipes constituting the hydrogen supply
pipe 80b and configured to independently control an H.sub.2 gas
flow rate at each of the nozzles constituting the hydrogen supply
nozzle 8b.
[0052] An oxygen supply nozzle 8a through which O.sub.2 gas as
oxygen-containing gas is supplied from the side of the inside of
the processing chamber 4 to the wafers 6 is connected to the side
lower part of the reaction tube 10, while penetrating the sidewall
of the reaction tube 10. The oxygen supply nozzle 8a is disposed in
a area corresponding to the wafer arrangement area, that is, a
cylindrical area surrounding the wafer arrangement area with facing
the wafer arrangement area at the inside of the reaction tube 10.
The oxygen supply nozzle 8a is configured by a plurality of (in
this embodiment, four) L-shaped nozzles each having a different
length and extending upward along the inner wall of the sidewall of
the reaction tube 10. Since the plurality of nozzles constituting
the oxygen supply nozzle 8a have different lengths in the wafer
arrangement direction, O.sub.2 gas is supplied into the reaction
tube 10 from a plurality of (in this embodiment, seven) locations
of the area corresponding to the wafer arrangement area, and an
oxygen concentration inside the reaction chamber 4 in the wafer
arrangement direction (vertical direction) is adjusted. The oxygen
supply nozzle 8a is installed along the inner wall nearer the inner
wall of the sidewall of the reaction tube 10 than the wafers 6. An
oxygen sub-nozzle is configured by the hydrogen supply nozzle 8a.
In addition, a second nozzle is configured by the oxygen supply
nozzle 8a.
[0053] Top surfaces of tips of the plurality of nozzles
constituting the oxygen supply nozzle 8a are closed, and at least
one gas ejection hole is installed in a side surface of the tip
portion of each nozzle. In FIG. 12, arrows extending from the
oxygen supply nozzle 8a toward the wafers 6 represent O.sub.2 gas
ejection directions from the respective gas ejection holes, and a
root part of each arrow represents each gas ejection hole. That is,
the gas ejection hole is directed toward the wafer and is
configured to eject O.sub.2 gas from the side inside the processing
chamber 4 toward the wafer 6 in a horizontal direction (direction
along a principal surface of the wafer). In the case of this
embodiment, each of the longest nozzle, the second longest nozzle
and the third longest nozzle is provided with two gas ejection
holes, and the shortest nozzle is provided with one gas ejection
hole. The plurality of (in this embodiment, seven) gas ejection
holes are installed at regular intervals. The lower gas ejection
hole of the longest nozzle is installed at an intermediate position
between the upper gas ejection hole of the longest nozzle and the
upper gas ejection hole of the second longest nozzle. In addition,
the lower gas ejection hole of the second longest nozzle is
installed at an intermediate position between the upper gas
ejection hole of the second longest nozzle and the upper gas
ejection hole of the third longest nozzle. In addition, the lower
gas ejection hole of the third longest nozzle is installed at an
intermediate position between the upper gas ejection hole of the
third longest nozzle and the gas ejection hole of the shortest
nozzle. These installations of the gas ejection holes make it
possible to supply O.sub.2 gas that is finely adjusted in the wafer
arrangement direction, and thus, the oxygen concentration can be
finely adjusted. A second gas ejection hole is configured by these
gas ejection holes.
[0054] An oxygen supply pipe 80a as an oxygen gas supply line is
connected to the oxygen supply nozzle 8a. The oxygen supply pipe
80a is configured by a plurality of (in this embodiment, four)
pipes that are connected to the plurality of nozzles constituting
the oxygen supply nozzle 8a, respectively. At the oxygen supply
pipe 80a, an oxygen gas supply source (not shown), an open-close
valve 96a, a mass flow controller (MFC) 95a as a flow rate control
unit (flow rate controller), and an open-close valve 94a are
installed sequentially from a upstream side. The open-close valve
96a, the mass flow controller 95a, and the open-close valve 94a are
installed in the respective pipes constituting the oxygen supply
pipe 80a and configured to independently control an O.sub.2 gas
flow rate at each of the nozzles constituting the oxygen supply
nozzle 8a.
[0055] A main oxygen gas supply system is mainly configured by the
oxygen supply nozzle 7a, the oxygen supply pipe 70a, the open-close
valve 91a, the mass flow controller 92a, and the open-close valve
93a. A sub oxygen gas supply system is mainly configured by the
oxygen supply nozzle 8a, the oxygen supply pipe 80a, the open-close
valve 94a, the mass flow controller 95a, and the open-close valve
96a. An oxygen gas supply system is configured by the main oxygen
gas supply system and the sub oxygen supply system.
[0056] A main hydrogen gas supply system is mainly configured by
the hydrogen supply nozzle 7b, the hydrogen supply pipe 70b, the
open-close valve 91b, the mass flow controller 92b, and the
open-close valve 93b. A sub hydrogen gas supply system is mainly
configured by the hydrogen supply nozzle 8b, the hydrogen supply
pipe 80b, the open-close valve 94b, the mass flow controller 95b,
and the open-close valve 96b. A hydrogen gas supply system is
configured by the main hydrogen gas supply system and the sub
hydrogen supply system.
[0057] A nitrogen gas supply system (not shown) is connected to the
oxygen gas supply system and the hydrogen gas supply system. The
nitrogen gas supply system is configured to supply nitrogen
(N.sub.2) gas as inert gas into the processing chamber 4 through
the oxygen supply pipes 70a and 80a and the hydrogen supply pipes
70b and 80b. The nitrogen gas supply system is mainly configured by
a nitrogen supply pipe (not shown), an open-close valve (not
shown), and a mass flow controller (not shown).
[0058] At a side lower part of the reaction tube 10, a gas exhaust
outlet 11 that exhausts the inside of the processing chamber is
installed. A gas exhaust pipe 50 as a gas exhaust line is connected
to the gas exhaust outlet 11. At the gas exhaust pipe 50, an auto
pressure controller (APC) 51 as a pressure regulation unit
(pressure controller), and a vacuum pump 52 as an exhaust unit
(exhaust device) are installed sequentially from the upstream side.
An exhaust system is mainly configured by the gas exhaust outlet
11, the gas exhaust pipe 50, the APC 51, and the vacuum pump
52.
[0059] The respective parts of the substrate processing apparatus,
such as the resistance heater 9, the mass flow controllers 92a,
92b, 95a and 95b, the open-close valves 91a, 91b, 93a, 93b, 94a,
94b, 96a and 96b, the APC 51, the vacuum pump 52, and the rotation
mechanism 14, are connected to a controller 100 as a control unit
(control part), and the controller 100 is configured to control the
operations of the respective parts of the substrate processing
apparatus. The controller 100 is configured as a computer including
a CPU, a storage device such as memory or HDD, a display device
such as FPD, and an input device such as keyboard or mouse.
[0060] Next, explanation will be given on a method of oxidizing a
wafer as a substrate, which is one of semiconductor device
manufacturing processes, by using the above-described oxidation
apparatus. In the following description, the operations of the
respective parts constituting the oxidation apparatus are
controlled by the controller 100.
[0061] When 1-batch quantity (for example 120 sheets) of wafers 6
are transferred and charged into the boat 3 by the substrate
transfer device (wafer charge), the boat 3 charged with the
plurality of sheets of wafers 6 is loaded into the processing
chamber 4 of the heat-treating furnace 5 that is maintained in a
heated state by the heater 9, and the inside of the reaction tube
10 is sealed by the seal cap 13. Subsequently, the inside of the
reaction tube chamber 10 is vacuumed by the vacuum pump 52, and
pressure inside the reaction tube 10 (pressure inside the furnace)
is controlled to be a predetermined process pressure lower than
atmospheric pressure by the APC 51. The boat 3 is rotated at a
predetermined rotating speed by the rotation mechanism 14. In
addition, temperature inside the processing chamber 4 (temperature
inside the furnace) is increased to a predetermined process
temperature.
[0062] After that, O.sub.2 gas and H.sub.2 gas are supplied into
the processing chamber 4 by the oxygen supply nozzle 7a and the
hydrogen supply nozzle 7b, respectively. That is, by opening the
open-close valves 91a and 93a, O.sub.2 gas whose flow rate is
controlled by the mass flow controller 92a is supplied into the
processing chamber 4 through the oxygen supply pipe 70a by the
oxygen supply nozzle 7a. In addition, by opening the open-close
valves 91b and 93b, H.sub.2 gas whose flow rate is controlled by
the mass flow controller 92b is supplied into the processing
chamber 4 through the hydrogen supply pipe 70b by the hydrogen
supply nozzle 7b. The O.sub.2 gas supplied from the oxygen supply
nozzle 7a and the H.sub.2 gas supplied from the hydrogen supply
nozzle 7b are mixed inside the buffer chamber 12a and then supplied
through the shower plate 12 into the processing chamber 4 in a
shower manner.
[0063] At this time, the oxygen supply nozzle 8a and the hydrogen
supply nozzle 8b also supply O.sub.2 gas and H.sub.2 gas into the
processing chamber 4, respectively. That is, by opening the
open-close valves 94a and 96a, O.sub.2 gas whose flow rate is
controlled by the mass flow controller 95a is supplied into the
processing chamber 4 through the oxygen supply pipe 80a by the
oxygen supply nozzle 8a. In addition, by opening the open-close
valves 94b and 96b, H.sub.2 gas whose flow rate is controlled by
the mass flow controller 95b is supplied into the processing
chamber 4 through the hydrogen supply pipe 80b by the hydrogen
supply nozzle 8b. The O.sub.2 gas supplied from the oxygen supply
nozzle 8a and the H.sub.2 gas supplied from the hydrogen supply
nozzle 8b are supplied into the processing chamber 4 from a
plurality of locations of the area corresponding to the wafer
arrangement area.
[0064] In this manner, the O.sub.2 gas and the H.sub.2 gas are
supplied from one end side of the wafer arrangement area inside the
processing chamber 4 and, at the same time, supplied from the
plurality of locations of the area corresponding to the wafer
arrangement area inside the processing chamber 4. The O.sub.2 gas
and the H.sub.2 gas supplied into the processing chamber 4 flow
down the inside of the processing chamber 4 and are exhausted from
the gas exhaust outlet 11 installed at the other end side of the
wafer arrangement area.
[0065] At this time, the O.sub.2 gas and the H.sub.2 gas react with
each other inside the depressurized processing chamber 4 heated by
the heater 5 to generate intermediate products such as H, O and OH.
As described in the specification of Japanese Patent Application
No. 2008-133772, filed by the present applicant, the representative
intermediate product directly contributing to the oxide film
formation among these intermediate products is atomic oxygen O, and
the intermediate products such as H and OH are not directly
involved in the surface reaction relating to the oxide film growth.
That is, among the intermediate products generated by the reaction
of the O.sub.2 gas and the H.sub.2 gas, the atomic oxygen O acts as
reactive species (oxidizing species) and the oxidation process is
performed on the wafers 6 so that silicon oxide films (SiO.sub.2
films) are formed as an oxide film on the surfaces of the wafers
6.
[0066] In this case, an example of process conditions (oxidation
process conditions) is as follows:
[0067] Process temperature (temperature inside the processing
chamber): 500 to 1,000.degree. C.,
[0068] Process pressure (pressure inside the processing chamber): 1
to 1,000 Pa,
[0069] Oxygen gas supply flow rate supplied from main nozzle: 2,000
to 4,000 sccm,
[0070] Hydrogen gas supply flow rate supplied from main nozzle: 0
to 500 sccm,
[0071] Oxygen gas supply flow rate supplied from sub-nozzle (total
flow rate): 1,000 to 3,000 sccm, and
[0072] Hydrogen gas supply flow rate supplied from sub-nozzle
(total flow rate): 1,500 to 2,000 sccm.
[0073] While maintaining the respective process conditions at
constant values within the respective ranges, the oxidation process
is performed on the wafers 6.
[0074] When the oxidation process of the wafers 6 is completed, the
open-close valves 91a, 91b, 93a, 93b, 94a, 94b, 96a and 96b are
closed, and the supply of the O.sub.2 gas and the H.sub.2 gas into
the processing chamber 4 is stopped. Then, by vacuum-exhaust the
inside of the reaction tube 10 or purging the inside of the
reaction tube 10 with inert gas, residual gases inside the reaction
tube 10 are removed. Subsequently, after the pressure inside the
furnace is returned back to the atmospheric pressure and the
temperature inside the furnace is decreased to a predetermined
temperature, the boat 3 holding the processed wafers 6 is unloaded
from the inside of the processing chamber 4, and the boat 3 is
queued at a predetermined position until all the processed wafers 6
held in the boat 6 are cooled. When the processed wafers 6 held in
the queued boat 3 are cooled down to a predetermined temperature,
the processed wafers 6 are discharged by the substrate transfer
device. In this way, a series of processes for oxidizing the wafers
6 are completed.
[0075] Hereinafter, the operation of the present invention will be
described with reference to FIG. 13 to FIG. 15. The following
description will be made on a case where O.sub.2 gas is supplied at
a certain flow rate (about several hundreds of sccm) together with
H.sub.2 gas from the vicinity of the gas ejection hole of the
hydrogen sub-nozzle (hydrogen supply nozzle 8b) installed so as to
correct the inter-wafer film thickness uniformity of the oxide
films formed on the wafers. The process conditions are as follows:
the process temperature is 850 to 950.degree. C.; the process
pressure is about 0.5 Torr; the flow rate of the H.sub.2 gas
supplied from the main nozzle is several hundreds of sccm; the flow
rate of the O.sub.2 gas supplied from the main nozzle is several
thousands of sccm; and the flow rate of the H.sub.2 gas supplied
from the sub-nozzle is about 1,500 sccm.
[0076] FIG. 13 shows the analysis result of the reaction behavior
in the gases and the wafer surfaces under those conditions (mole
density distribution of atomic oxygen O inside the processing
chamber). According to the result, the partial pressure of the
atomic oxygen O is locally lowered in the vicinity that supplies
the H.sub.2 gas and the O.sub.2 gas. However, as the H.sub.2 gas
and the O.sub.2 gas infiltrate into the central part of the wafer
due to concentration diffusion, the reaction to generate atomic
oxygen O progresses, and the concentration of the atomic oxygen O
increases toward the central part of the wafer. As described above,
since the film thickness of the oxide film formed on the surface of
the wafer depends on the concentration of the gas-phase atomic
oxygen O, the intra-wafer film thickness distribution of the oxide
film formed on the surface of the wafer in the vicinity that
supplies the H.sub.2 gas and the O.sub.2 gas can be the
center-convex () distribution (during the processing of the bare
wafer).
[0077] The effect is not limited to the vicinity that supplies the
H.sub.2 gas and the O.sub.2 gas, but generates even in the upstream
side and the downstream side relative to the supply point. In
particular, the effect range is wide at the downstream side, and
the effect reaches up to the lower side (downstream) of about 150
mm under the above-described process conditions. That is, if an
arbitrary-amount supply point (gas ejection hole) of H.sub.2 gas
and O.sub.2 gas is installed at a pitch of about 150 mm, the
intra-wafer film thickness uniformity of the oxide film formed on
the surface of the wafer with respect to the entire wafer
arrangement area can be the center-convex () distribution (during
the processing of the bare wafer). For example, when assuming the
vertical furnace where 100 to 150 sheets of wafers are stacked at a
pitch of about 100 mm, it is necessary to install H.sub.2 gas,
O.sub.2 gas supply points (gas ejection holes) at 6 to 10
locations. That is, it is necessary to install the gas ejection
holes of the hydrogen sub-nozzles and the gas ejection holes of the
oxygen sub-nozzles at 6 to 10 locations at a pitch of about 150 mm,
respectively. At the oxidation furnace of FIG. 12, the gas ejection
holes of the hydrogen sub-nozzles and the gas ejection holes of the
oxygen sub-nozzles are installed at seven locations at a pitch of
about 150 mm, respectively.
[0078] FIG. 14 shows the analysis result of the inter-wafer and
intra-wafer concentrations of atomic oxygen O under the
above-described process conditions. In FIG. 14, a rhombic point
(.diamond.) is a condition that the inter-wafer film thickness
uniformity of the oxide films formed on the wafers is corrected by
the halfway supply of H.sub.2 gas only. In FIG. 14, a square point
(.quadrature.) is a condition that O.sub.2 gas is further added to
the position indicated by a broken line in the drawing under the
condition that corrects the inter-wafer film thickness uniformity
by the halfway supply of H.sub.2 gas only (condition of the rhombic
point (.diamond.)). As described above, the addition of the O.sub.2
gas increases the center-convex () distribution degree of the
intra-wafer film thickness distribution of the oxide film formed on
the wafer (portion A of the drawing). Meanwhile, there occurs the
phenomenon that the film thickness is reduced in the vicinity where
the O.sub.2 gas is added (portion B of the drawing), and thus, the
inter-wafer film thickness uniformity of the oxide films formed on
the wafers is deteriorated.
[0079] A means for avoiding this problem will be described with
reference to FIG. 15. A square point (.quadrature.) of FIG. 15 is
the same condition as the square point (.quadrature.) of FIG. 14
(condition that the O.sub.2 gas is further added to the condition
that the inter-wafer film thickness uniformity is corrected by the
halfway supply of the H.sub.2 gas only). In FIG. 15, a triangular
point (.DELTA.) is a condition that H.sub.2 gas is further added to
the position indicated by a broken line in the drawing under the
condition of the square point (.quadrature.) (a flow rate of
H.sub.2 gas is increased). By further adding the H.sub.2 gas to the
position where the O.sub.2 gas is added (by increasing the flow
rate of the H.sub.2 gas), it is possible to increase the film
thickness of the position where the film thickness is reduced due
to the addition of the O.sub.2 gas (portion C of the drawing).
Also, regarding the intra-wafer film thickness uniformity, the
center-convex () distribution degree of the intra-wafer film
thickness distribution is more increased by further adding the
H.sub.2 gas (by increasing the flow rate of the H.sub.2 gas).
[0080] The control effect of the intra-wafer film thickness
uniformity by the addition of the O.sub.2 gas as described above
(increase effect of the center-convex () distribution degree of the
intra-wafer film thickness distribution), the film thickness
increase effect, and the control effect of the intra-wafer film
thickness uniformity (further increase effect of the center-convex
() distribution degree of the intra-wafer film thickness
distribution) by the addition of the H.sub.2 gas operate around the
gas supply point. In order for efficient combination of these
effects, it is preferable that the O.sub.2 gas and the H.sub.2 gas
are supplied from the substantially same height. That is, it is
preferable that the height of the H.sub.2 gas supply point (gas
ejection hole) is matched with the height of the O.sub.2 gas supply
point (gas ejection hole). In the oxidation furnace of FIG. 12, the
plurality of gas ejection holes provided in the hydrogen sub-nozzle
(hydrogen supply nozzle 8b) and the plurality of gas ejection holes
provided in the oxygen sub-nozzle (oxygen supply nozzle 8a) are
installed at the same heights, respectively. That is, the number
and the arrangement pitch of the gas ejection holes provided in the
hydrogen supply nozzle 8b are equal to the number and the
arrangement pitch of the gas ejection holes provided in the oxygen
supply nozzle 8a, and the gas ejection holes provided in the
hydrogen supply nozzle 8b and the gas ejection holes provided in
the oxygen supply nozzle 8a are installed at the same heights,
respectively, such that they are in 1:1 correspondence with one
another. Therefore, the control of the intra-wafer film thickness
uniformity is possible while the inter-wafer film thickness
uniformity is maintained (the intra-wafer film thickness
distribution can be actively the center-convex () distribution),
and it is possible to prevent the prominent center-concave ()
distribution of the intra-wafer film thickness distribution having
occurred in the processing of the wafer with deep recessed patterns
such as STI (wafer with large consumption of atomic oxygen O).
[0081] Hereinafter, details about the control operation of the
intra-wafer film thickness uniformity by the addition of the
O.sub.2 gas and the film thickness increase effect by the addition
of the H.sub.2 gas will be described with reference to FIG. 16 and
FIG. 17.
[0082] FIG. 16 schematically shows the concentration distribution
of atomic oxygen O in the vicinity of the supply points when
H.sub.2 gas and O.sub.2 gas are supplied from the hydrogen
sub-nozzle (hydrogen supply nozzle 8b) and the oxygen sub-nozzle
(oxygen supply nozzle 8a), respectively. In FIG. 16 and FIG. 17,
the hydrogen sub-nozzle (hydrogen supply nozzle 8b) and the oxygen
sub-nozzle (oxygen supply nozzle 8a) are overlappingly displayed,
and both the sub-nozzles are collectively represented by a
sub-nozzle 8. Since the pressure of the processing chamber is
constant at about 0.5 Torr, the concentration (partial pressure) of
the atomic oxygen O in the vicinity of the H.sub.2 gas and O.sub.2
gas supply points is lowered by a dilution effect. Therefore,
contrary to the behavior of the area where no gas is supplied from
the sub-nozzle according to the prior art (as shown in FIG. 10, the
concentration of the atomic oxygen O is lowered over the central
part of the wafer by the concentration diffusion from mainstream
flowing down between the edge part of the wafer and the inner wall
of the reaction tube and by the consumption of the atomic oxygen O
on the surface of the wafer), the concentration of the atomic
oxygen O is lowered at the edge part of the wafer, and thus, the
concentration of the atomic oxygen O tends to be increased by the
weakening of the dilution effect over the central part of the wafer
and the progress of the reaction to generate the atomic oxygen O.
Finally, the balance is formed in such a state that the consumption
of the atomic oxygen O for the film growth on the surface of the
wafer is added to this phenomenon.
[0083] FIG. 17A schematically shows the mole density of the atomic
oxygen O in the case of FIG. 17B, FIG. 17C, and FIG. 17C. FIG. 17B
schematically shows the film thickness map (sectional view) on the
surface of the wafer (assuming the bare wafer film-forming process)
when no gas is supplied from the sub-nozzle (no nozzle). FIG. 17C
schematically shows the film thickness map (sectional view) on the
surface of the wafer (assuming the bare wafer film-forming process)
when only H.sub.2 gas is supplied from the sub-nozzle (only H.sub.2
gas supply from the nozzle). FIG. 17D schematically shows the film
thickness map (sectional view) on the surface of the wafer
(assuming the bare wafer film-forming process) when H.sub.2 gas and
O.sub.2 gas are supplied from the sub-nozzle (O.sub.2, H.sub.2
supply from the nozzle with an increased amount of H.sub.2 with
respect to the case of FIG. 17C). When no gas is supplied from the
sub-nozzle, as described above, the concentration diffusion from
the periphery part of the wafer is dominant, and also, the
concentration of the atomic oxygen O is high at the periphery part
of the wafer and gets lower over the central part of the wafer by
the consumption of the atomic oxygen O on the surface of the wafer.
As shown in FIG. 17B, the intra-wafer film thickness distribution
becomes the center-concave () distribution. When only H.sub.2 gas
is supplied by the sub-nozzle, the concentration (partial pressure)
of the atomic oxygen O is lowered as much as the added H.sub.2 gas
in the vicinity of the supply point, and thus, it is possible to
suppress the concentration of the atomic oxygen O from increasing
at the periphery part of the wafer. As the reaction to generate the
atomic oxygen O progresses over the central part of the wafer
(H.sub.2 gas addition effect), the concentration of the atomic
oxygen O gets higher toward the central part of the wafer. As shown
in FIG. 17C, the intra-wafer film thickness uniformity becomes the
center-convex () distribution. When H.sub.2 gas and O.sub.2 gas are
supplied by the sub-nozzle, the concentration (partial pressure) of
the atomic oxygen O is further lowered as much as the added H.sub.2
gas and O.sub.2 gas in the vicinity of the supply point, and thus,
it is possible to suppress the concentration of the atomic oxygen O
from increasing at the periphery part of the wafer. In addition,
like the case where only H.sub.2 gas is supplied over the central
part of the wafer, as the reaction to generate the atomic oxygen O
progresses over the central part of the wafer (H.sub.2 gas addition
effect), the concentration of the atomic oxygen O gets higher
toward the central part of the wafer. Moreover, since a large
amount of H.sub.2 gas is supplied so as to correct the film
thickness reduced by the addition of the O.sub.2 gas, an amount of
atomic oxygen O generated over the central part of the wafer
becomes larger than when only H.sub.2 gas is supplied.
Consequently, as shown in FIG. 17D, the center-convex ()
distribution degree can be stronger than when only H.sub.2 gas is
supplied. That is, it can be said that the control range of the
film thickness distribution is wider than when only H.sub.2 gas is
supplied.
[0084] As described above, by supplying H.sub.2 gas and O.sub.2 gas
halfway, the intra-wafer film thickness uniformity can be improved
(controlled) by preventing the prominent center-concave ()
distribution having occurred in the processing of the wafer with
deep recessed patterns such as STI (wafer with large consumption of
atomic oxygen O), while maintaining the inter-wafer film thickness
uniformity of the oxide films formed on the stacked wafers.
[0085] In the above-described embodiment, the O.sub.2 gas supplied
from the sub-nozzle mainly functions to dilute the concentration of
the atomic oxygen O in the vicinity of the supply point. Therefore,
the same effect can be obtained even if supplying inert gas (for
example, N.sub.2, He, Ne, Ar, Xe, etc.) having no influence on the
wafer processing, instead of supplying O.sub.2 gas from the
sub-nozzle. That is, O.sub.2 gas and H.sub.2 gas may be supplied
from the oxygen supply nozzle 7a and the hydrogen supply nozzle 7b
constituting the main nozzle, respectively, and H.sub.2 gas may be
supplied from the hydrogen sub-nozzle (hydrogen supply nozzle 8b),
and inert gas may be supplied from the oxygen sub-nozzle (oxygen
supply nozzle 8a).
[0086] Furthermore, while the case of using the oxygen gas as the
oxygen-containing gas and the case of using the hydrogen gas as the
hydrogen-containing gas have been described in the above-described
embodiment, at least one gas selected from the group consisting of
oxygen (O.sub.2) gas and nitrous oxide (N.sub.2O) gas may be used
as the oxygen-containing gas, and at least one gas selected from
the group consisting of hydrogen (H.sub.2) gas, ammonia (NH.sub.3)
gas and methane (CH.sub.4) gas may be used as the
hydrogen-containing gas.
Second Embodiment
[0087] Next, a second embodiment of the present invention will be
described.
[0088] While the example in which the oxygen sub-nozzle (oxygen
supply nozzle 8a) is configured by the plurality of nozzles (multi
nozzles) each having a different length has been described in the
above-described first embodiment, the oxygen supply nozzle 8a may
also be configured by a single nozzle (multi-hole nozzle) having a
plurality of gas ejection holes. Hereinafter, an example in which
the oxygen sub-nozzle is configured by a single multi-hole nozzle
will be described as the second embodiment.
[0089] As a substrate processing apparatus in accordance with a
second embodiment of the present invention, a batch-type vertical
semiconductor manufacturing apparatus (oxidation apparatus) will be
described with reference to FIG. 18. FIG. 18 is a schematic
sectional view showing a configuration example of a heat-treating
furnace (oxidation furnace) relevant to the second embodiment.
[0090] Only difference between the oxidation furnace (FIG. 18) of
the second embodiment and the oxidation furnace (FIG. 12) of the
first embodiment is the configuration of the sub oxygen gas supply
system including the oxygen supply nozzle 8a. The other
configurations are the same as the first embodiment. In this
embodiment, the sub oxygen gas supply system is mainly provided
with a single oxygen supply nozzle 8a having a plurality of gas
ejection holes, an oxygen supply pipe 80a configured by a single
pipe connected to the oxygen supply nozzle 8a, an open-close valve
94a, a mass flow controller 95a, and an open-close valve 96a
installed in the oxygen supply pipe 80a. In FIG. 18, arrows
extending from the oxygen supply nozzle 8a toward the wafers 6
represent O.sub.2 gas ejection directions from the respective gas
ejection holes, and root parts of the arrows represent the
respective gas ejection holes. This embodiment is substantially
similar to the first embodiment in that the plurality of gas
ejection holes provided in the oxygen supply nozzle 8a and the
plurality of gas ejection holes provided in the hydrogen supply
nozzle 8b are installed at the same heights, respectively, and the
number (seven) of the gas ejection holes provided in the oxygen
supply nozzle 8a is equal to the number (seven) of the gas ejection
holes provided in the hydrogen supply nozzle 8b. In FIG. 18, the
same reference numerals as those of FIG. 12 are assigned to the
substantially same elements as those of FIG. 12 and their
description will be omitted.
[0091] In this embodiment, a first nozzle is configured by the
hydrogen supply nozzle 8b provided with a plurality of nozzles each
having a different length, and a first gas ejection hole is
configured by a plurality of gas ejection holes provided in the
hydrogen supply nozzle 8b. In addition, a second nozzle is
configured by the oxygen supply nozzle 8a provided with a single
multi-hole nozzle, and a second gas ejection hole is configured by
the plurality of gas ejection holes provided in the oxygen supply
nozzle 8a. In this embodiment, while the gas ejection holes may be
configured by a plurality of holes having the same diameter, they
may also be configured by a plurality of holes each having a
different diameter so that O.sub.2 gas (dilution gas) is ejected
from the gas ejection holes at a uniform flow rate.
[0092] According to this embodiment, the same effect as the first
embodiment can obtained, and moreover, the apparatus configuration
can be simplified and the cost can be down.
Third Embodiment
[0093] Next, a third embodiment of the present invention will be
described.
[0094] In the oxidation furnaces described above in the first and
second embodiments, the arrangement pitch of the gas ejection holes
provided in the oxygen sub-nozzle (oxygen supply nozzle 8a) is
greater than the wafer arrangement pitch (for example, about 150-mm
pitch), and the O.sub.2 gas ejection holes (supply direction) are
directed toward the wafers. However, in this case, as shown in FIG.
19, the inventors found that there were cases that the intra-wafer
film thickness distribution became extremely center-convex () due
to the influence of the O.sub.2 gas flow (inertia). That is, the
inventors found that the intra-wafer film thickness distribution
improvement (center-convex () formation) effects were different in
the vicinity of the O.sub.2 gas supply point and the other areas.
Regarding this, the inventors found that if the gas ejection holes
provided in the oxygen sub-nozzle (oxygen supply nozzle 8a) were
installed as many as at least the process wafers so that they were
at least in 1:1 correspondence with the plurality of process
wafers, the intra-wafer film thickness uniformity could be improved
by controlling the reaction such that atomic oxygen O was generated
much more at the central part of the process wafer, while
preventing the local intra-wafer film thickness distribution
tendency change (center-convex () formation). In this
specification, for convenience's sake, a product wafer as a product
substrate to be processed is simply referred to as a wafer or a
process wafer. Likewise, in this embodiment, a wafer or a process
wafer refers to a product wafer. Hereinafter, explanation will be
given on an example, as a third embodiment, in which the gas
ejection holes of the oxygen sub-nozzle are installed as many as at
least the process wafers (product wafer) so that they are at least
in 1:1 correspondence with the plurality of process wafers.
[0095] As a substrate processing apparatus in accordance with a
third embodiment of the present invention, a batch-type vertical
semiconductor manufacturing apparatus (oxidation apparatus) will be
described with reference to FIG. 20. FIG. 20 is a schematic
sectional view showing a configuration example of a heat-treating
furnace (oxidation furnace) relevant to the third embodiment.
[0096] Only difference between the oxidation furnace (FIG. 20) of
the third embodiment and the oxidation furnace (FIG. 18) of the
second embodiment is the configuration of the oxygen supply nozzle
8a. The other configurations are the same as the second embodiment.
In this embodiment, the oxygen supply nozzle 8a is provided with a
single nozzle (multi-hole nozzle) having a plurality of gas
ejection holes and extends along the inner wall of the sidewall of
the reaction tube 10 until it reaches the top process wafer. That
is, the oxygen supply nozzle 8a extends over the entire wafer
arrangement area. In FIG. 20, arrows extending from the oxygen
supply nozzle 8a toward the wafers 6 represent O.sub.2 gas ejection
directions from the respective gas ejection holes, and root parts
of the arrows represent the respective gas ejection holes. That is,
in order to uniformly supply O.sub.2 gas to each of the process
wafers, the oxygen supply nozzle 8a is provided with as many gas
ejection holes as at least the process wafers so that the gas
ejection holes are in 1:1 correspondence with at least the
plurality of process wafers. For example, when the number of the
process wafers is 120 sheets, at least 120 gas ejection holes are
installed so that they correspond to at least the respective
process wafers. Moreover, for example, when side dummy wafers are
arranged above and under the process wafers, and the number of
upper dummy wafers, process wafers, and lower dummy wafers is 10
sheets, 100 sheets, and 10 sheets, respectively, at least 100 gas
ejection holes are installed so that they correspond to at least
the 100 process wafers. In addition to the configuration in which
as many gas ejection holes as the process wafers are installed so
that they correspond to the respective process wafers, the gas
ejection holes may be installed at locations that do not correspond
to the process wafers, that is, areas other than the wafer
arrangement area. For example, the gas ejection holes may be
installed in an area corresponding to a dummy wafer arrangement
area where the above-described side dummy wafers are arranged, or
an area above or under the corresponding area. When the gas
ejection holes are installed in the area corresponding to the dummy
wafer arrangement area, it is preferable that as many gas ejection
holes as the dummy wafers are installed so that they correspond to
the respective dummy wafers in the region adjacent to at least the
process wafers. In this way, the flow of the O.sub.2 gas to the
dummy wafers in the region adjacent to the process wafers may be
made to be equal to the flow of the O.sub.2 gas to the process
wafers, and may be made not to disturb the flow of gas to the
process wafers disposed in the vicinity of the dummy wafers. The
gas ejection holes are configured by relatively small holes so that
O.sub.2 gas is ejected to the respective process wafers at a
uniform flow rate. The oxygen supply nozzle 8a is configured by,
for example, a multi-hole nozzle in which as many holes of about
.phi.0.5-1 mm as the process wafers are installed in a pipe of
about .phi.10-20 mm. The oxygen supply nozzle 8a may be configured
to supply O.sub.2 gas uniformly to all the process wafers, and may
be configured by a plurality of nozzles each having a different
length, just like in the first embodiment. In FIG. 20, the same
reference numerals as those of FIG. 12 and FIG. 18 are assigned to
the substantially same elements as those of FIG. 12 and FIG. 18 and
their description will be omitted.
[0097] In this embodiment, a first nozzle is configured by the
hydrogen supply nozzle 8b provided with a plurality of nozzles each
having a different length, and a first gas ejection hole is
configured by a plurality of gas ejection holes provided in the
hydrogen supply nozzle 8b. In addition, a second nozzle is
configured by the oxygen supply nozzle 8a provided with a single
multi-hole nozzle, and a second gas ejection hole is configured by
the plurality of gas ejection holes that are provided in the oxygen
supply nozzle 8a as many as at least the process wafers so that
they correspond to at least the respective process wafers.
[0098] In this embodiment, the arrangement pitch of the gas
ejection holes provided in the oxygen supply nozzle 8a is set to be
equal to the wafer arrangement pitch. In addition, the respective
distances between the respective gas ejection holes provided in the
oxygen supply nozzle 8a and the respective wafers corresponding to
the respective gas ejection holes in the wafer arrangement
direction are set to be equal to one another. Moreover, the number
of the gas ejection holes provided in the hydrogen supply nozzle 8b
is set to be smaller than the number of the gas ejection holes
provided in the oxygen supply nozzle 8a.
[0099] In this embodiment, an example of process conditions
(oxidation process conditions) in the case of using the oxidation
furnace is as follows:
[0100] Process temperature (temperature inside the processing
chamber): 500 to 1,000.degree. C.,
[0101] Process pressure (pressure inside the processing chamber): 1
to 1,000 Pa,
[0102] Oxygen gas supply flow rate supplied from main nozzle: 0 to
2,000 sccm,
[0103] Hydrogen gas supply flow rate supplied from main nozzle: 0
to 500 sccm,
[0104] Oxygen gas supply flow rate supplied from sub-nozzle (total
flow rate): 3,000 to 5,000 sccm, and
[0105] Hydrogen gas supply flow rate supplied from sub-nozzle
(total flow rate): 1,500 to 2,000 sccm.
While maintaining the respective process conditions at constant
values within the respective ranges, the oxidation process is
performed on the wafers 6. While the lower limits of the oxygen gas
supply flow rate and the hydrogen gas supply flow rate supplied
from the main nozzle are 0 sccm, this represents a case that
performs the oxidation process by using only the sub-nozzle,
without using the main nozzle. In this embodiment, as such, the
oxidation process may be performed by using only the
sub-nozzle.
[0106] Hereinafter, the operation of this embodiment will be
described with reference to FIG. 21 to FIG. 23.
[0107] First, the control operation of the intra-wafer film
thickness uniformity by the addition of O.sub.2 gas will be
described with reference to FIG. 21 and FIG. 22. FIG. 21 and FIG.
22 schematically show the concentration distributions of atomic
oxygen O in the vicinity of the supply point when O.sub.2 gas is
supplied from the oxygen sub-nozzle (oxygen supply nozzle 8a). In
FIG. 21 and FIG. 22, white-background arrows extending from the
oxygen supply nozzle 8a toward the wafers 6 represent O.sub.2 gas
ejection directions from the gas ejection holes, and root parts of
the arrows represent the respective gas ejection holes. Since the
pressure inside the processing chamber is constant at about 0.5
Torr, the concentration (partial pressure) of the atomic oxygen O
in the vicinity of the O.sub.2 gas supply point is lowered by a
dilution effect. Therefore, contrary to the behavior of the area
where no gas is supplied from the sub-nozzle according to the prior
art (the concentration of the atomic oxygen O is lowered over the
central part of the wafer by the concentration diffusion from
mainstream flowing down between the edge part of the wafer and the
inner wall of the reaction tube and by the consumption of the
atomic oxygen O on the surface of the wafer), the concentration of
the atomic oxygen O is lowered at the edge part of the wafer, and
thus, the concentration of the atomic oxygen O tends to be
increased by the weakening of the dilution effect over the central
part of the wafer and the progress of the reaction to generate the
atomic oxygen O. Finally, the balance is formed in such a state
that the consumption of the atomic oxygen O for the film growth on
the surface of the wafer is added to this phenomenon.
[0108] In the oxidation furnaces of the first and second
embodiments, since the number of the O.sub.2 gas supply points is
small (for example, 1 location with respect to 15 wafers), the
dilution effect remarkably operates in the vicinity of the supply
points by the influence of the flow (inertia) during the O.sub.2
gas ejection, and thus, the O concentration is lowered in some
cases. In this case, as shown in FIG. 21, the intra-wafer
concentration distribution of the atomic oxygen O on each wafer 6
is changed at each wafer. As a result, the intra-wafer film
thickness distribution tendency (center-convex () formation) is
locally changed. Therefore, in this embodiment, as many O.sub.2 gas
supply points as at least the process wafers are installed so that
they correspond to at least the respective process wafers. That is,
in this embodiment, the O.sub.2 gas supply points are installed
with respect to all the process wafers, and the O.sub.2 gas is
uniformly supplied from those points to the respective process
wafers. In this way, as shown in FIG. 22, since the intra-wafer
concentration distributions of the atomic oxygen O on the
respective wafers 6 are equalized, it is possible to prevent the
change of the local intra-wafer film thickness distribution
tendency caused by the influence of the flow (inertia) during the
above-described O.sub.2 gas ejection. As a result, the intra-wafer
film thickness distributions of all the process wafers can be
uniformly improved (the film thickness distributions can be
suppressed from being the mortar distribution).
[0109] On the other hand, when the number of the O.sub.2 gas supply
points is slightly smaller than the number of the process wafers
(for example, when 115 O.sub.2 gas supply points are installed with
respect to 120 process wafers), the O.sub.2 gas supply points do
not correspond to the respective process wafers. In this case, in
some regions, the O.sub.2 gas is not uniformly supplied to the
respective process wafers and, in some regions, the intra-wafer
concentration distributions of the atomic oxygen O on the process
wafers are different at the respective process wafers. Thus, the
phenomenon described (change of the local intra-wafer film
thickness distribution tendency due to the influence of the flow
(inertia) during the O.sub.2 gas ejection) is generated to no small
extent, and the processing quality is lowered as a whole.
[0110] Furthermore, in this embodiment, the distances between the
O.sub.2 gas supply points and the corresponding process wafers in
the height direction are equalized as a whole. That is, in this
embodiment, since the height-direction pitch of the O.sub.2 gas
supply points and the stacking pitch of the process wafers are
equalized, the relationship between the O.sub.2 gas supply points
and the positions of the corresponding process wafers is always
constant. Therefore, since the O concentration ripple forms shown
in FIG. 22 are equal on all the process wafers, the intra-wafer
uniformity of all the process wafers can be uniformly improved.
[0111] On the other hand, when the distances between the O.sub.2
gas supply points and the corresponding process wafers in the
height direction are not equalized at the respective locations
(distributed irregularly), that is, the relationship between the
O.sub.2 gas supply points and the positions of the corresponding
process wafers is not constant, the O concentration ripple forms
are changed according to the process wafers, and thus, variations
occur in the intra-wafer film thickness uniformity improvement
effect.
[0112] FIG. 23 shows the intra-wafer film thickness distribution
result (O.sub.2 halfway supply to all the wafers) when O.sub.2 gas
is supplied from the sub-nozzle at a flow rate of about 5,000 sccm
under process conditions that the process temperature is about
900.degree. C., the process pressure is about 0.5 Torr, the flow
rate of the H.sub.2 gas supplied from the main nozzle is several
hundreds of sccm, the flow rate of the O.sub.2 gas supplied from
the main nozzle is several thousands of sccm, and the total flow
rate of the H.sub.2 gas supplied from the sub-nozzle is about 1,500
sccm, by using the oxidation furnace of this embodiment. For the
purpose of comparison, FIG. 23 also shows the experimental result
of the intra-wafer film thickness uniformity of FIG. 19 (No O.sub.2
halfway supply, the O.sub.2 halfway supply). It can be seen from
FIG. 23 that, by uniformly supplying O.sub.2 gas with respect to
all the process wafers, it is possible to prevent the change of the
local intra-wafer film thickness distribution tendency, and the
intra-wafer film thickness distribution of all the process wafers
can be uniformly improved. From the above description, by the
uniform halfway supply of the O.sub.2 gas to the respective process
wafers, it is possible to uniformly lessen the mortar tendency of
the intra-wafer film thickness distributions of all the process
wafers while maintaining the inter-wafer film thickness
uniformity.
[0113] In this embodiment, since the arrangement pitch of the
H.sub.2 gas supply points (ejection holes) is greater than the
wafer arrangement pitch and the arrangement pitch of the O.sub.2
gas supply points (for example, about 150-mm pitch), the H.sub.2
gas supply points are not installed as many as the process wafers
such that they correspond to the respective process wafers. That
is, in this embodiment, the number of the H.sub.2 gas supply points
is smaller than the number of the process wafers and the number of
the O.sub.2 gas supply points. For example, when the number of the
process wafers is 120 sheets, at least 120 O.sub.2 gas supply
points are installed so that they correspond to at least the
respective process wafers. On the contrary, 7 H.sub.2 gas supply
points (1 location with respect to 15 wafers) are installed. The
reason why as many H.sub.2 gas supply points as the process wafers
need not be installed is as follows. That is, since the H.sub.2 gas
has a smaller molecular diameter than the O.sub.2 gas and has a
higher diffusion rate under the environment of about 0.5 Torr, it
is sufficiently diffused even though the supply points are not
installed with respect to the respective process wafers. Therefore,
it can be said that the intra-wafer film thickness uniformity is
less influenced by the existence/nonexistence of the supply points
of the H.sub.2 gas, and the processing quality necessary for the
actual state can be sufficiently satisfied even with a smaller
number of the supply points than the number of the process wafers.
In this embodiment, the height of the hydrogen supply nozzle 8b is
lower than the height of the oxygen supply nozzle 8a. However, the
height of the hydrogen supply nozzle 8b may also be equal to the
height of the oxygen supply nozzle 8a. That is, like the oxygen
supply nozzle 9a, the hydrogen supply nozzle 8b may reach up to the
height of the top wafer.
[0114] In this embodiment, as described above, the oxidation
process may be performed by using only the sub-nozzle, without
using the main nozzle. That is, the oxidation process may performed
by supplying O.sub.2 gas and H.sub.2 gas from only the sub-nozzle
(oxygen supply nozzle 8a, hydrogen supply nozzle 8b), without
supplying O.sub.2 gas and H.sub.2 gas from the main nozzle 7
(oxygen supply nozzle 7a, hydrogen supply nozzle 7b). In this case,
inert gas such as N.sub.2 gas may be supplied from the main nozzle
7. In this way, the concentration of H.sub.2 gas, O.sub.2 gas or
atomic oxygen O at the upper part inside the processing chamber can
be finely adjusted. Moreover, gas curtain by the inert gas may be
formed, and unnecessary diffusion of H.sub.2 gas, O.sub.2 gas or
atomic oxygen O can be suppressed at the upper part inside the
processing chamber.
[0115] Additionally, in this embodiment, the oxidation process may
be performed even though one of O.sub.2 gas and H.sub.2 gas is
supplied from the main nozzle. That is, the oxidation process may
be performed by supplying H.sub.2 gas from the hydrogen supply
nozzle 7b as the main nozzle and supplying O.sub.2 gas and H.sub.2
gas from the sub-nozzle (oxygen supply nozzle 8a, hydrogen supply
nozzle 8b), without supplying O.sub.2 gas from the oxygen supply
nozzle 7a as the main nozzle. In this case, the concentration of
H.sub.2 gas at the upper part of the processing chamber can be
finely adjusted, and the film thickness of the oxide film formed on
the process wafer at the upper part of the wafer arrangement area
can be finely adjusted. In addition, the oxidation process may be
performed by supplying O.sub.2 gas from the oxygen supply nozzle 7a
as the main nozzle and supplying O.sub.2 gas and H.sub.2 gas from
the sub-nozzle (oxygen supply nozzle 8a, hydrogen supply nozzle
8b), without supplying H.sub.2 gas from the hydrogen supply nozzle
7b as the main nozzle. In this case, the concentration of O.sub.2
gas at the upper part of the processing chamber can be finely
adjusted, and the film thickness of the oxide film formed on the
process wafer at the upper part of the wafer arrangement area can
be finely adjusted.
Fourth Embodiment
[0116] Next, a fourth embodiment of the present invention will be
described.
[0117] In the oxidation furnace of the above-described third
embodiment, the above explanation has been given on the example in
which the arrangement pitch of the gas ejection holes installed in
the hydrogen sub-nozzle (hydrogen supply nozzle 8b) is greater than
the wafer arrangement pitch and the arrangement pitch of the
O.sub.2 gas ejection holes (for example, about 150-mm pitch). That
is, the example in which the number of the H.sub.2 gas ejection
holes is smaller than the number of the process wafers and the
number of the O.sub.2 gas ejection holes has been described above.
As described above, the processing quality necessary for the actual
state can be sufficiently satisfied even when the H.sub.2 gas
ejection holes are not installed as many as the process wafers. On
the other hand, the inventors found that the further excellent
intra-wafer and inter-wafer film thickness uniformity could be
obtained by installing as many H.sub.2 gas ejection holes as at
least the process wafers, just like the O.sub.2 gas ejection holes,
so that they correspond to at least the respective process wafers.
Hereinafter, explanation will be given on an example, as the fourth
embodiment, in which the gas ejection holes of the hydrogen
sub-nozzle are installed as many as at least the process wafers,
just like the gas ejection holes of the oxygen sub-nozzle, so that
they correspond to at least the respective process wafers.
[0118] As a substrate processing apparatus in accordance with a
fourth embodiment of the present invention, a batch-type vertical
semiconductor manufacturing apparatus (oxidation apparatus) will be
described with reference to FIG. 24. FIG. 24 is a schematic
sectional view showing a configuration example of a heat-treating
furnace (oxidation furnace) relevant to the fourth embodiment.
[0119] Only difference between the oxidation furnace (FIG. 24) of
the fourth embodiment and the oxidation furnace (FIG. 20) of the
third embodiment is the configuration of the hydrogen supply nozzle
8b. The other configurations are the same as the third embodiment.
In this embodiment, the hydrogen supply nozzle 8b is configured by
a plurality (four) of nozzles each having a different length, and
the longest nozzle reaches up to the top process wafer along the
inner wall of the sidewall of the reaction tube 10. That is, the
hydrogen supply nozzle 8b extends over the entire wafer arrangement
area. In order to supply H.sub.2 gas uniformly to the respective
process wafers, the hydrogen supply nozzle 8b is provided with as
many gas ejection holes as at least the process wafers so that they
correspond to at least the respective process wafers. For example,
when the number of the process wafers is 120 sheets, at least 120
H.sub.2 gas ejection holes are installed so that they correspond to
the respective process wafers. In this case, each of the plurality
(four) of nozzles constituting the hydrogen supply nozzle 8b is
provided with 30 H.sub.2 gas ejection holes. In addition to the
configuration in which as many H.sub.2 gas ejection holes as the
process wafers are installed so that they correspond to the
respective process wafers, the H.sub.2 gas ejection holes may be
installed at locations that do not correspond to the process
wafers, that is, areas other than the wafer arrangement area. The
gas ejection holes are configured by relatively small holes so that
H.sub.2 gas is ejected to the respective process wafers at a
uniform flow rate. The hydrogen supply nozzle 8b is configured by,
for example, a plurality (four) of multi-hole nozzles in which as
many holes of about .phi.0.5-1 mm as the process wafers are
installed in a plurality (four) of pipes of about .phi.10-20 mm.
The hydrogen supply nozzle 8b may be configured to supply H.sub.2
gas uniformly to all the process wafers, and may be configured by a
single multi-hole nozzle. In FIG. 24, the same reference numerals
as those of FIG. 12, FIG. 18 and FIG. 20 are assigned to the
substantially same elements as those of FIG. 12, FIG. 18 and FIG.
20 and their description will be omitted.
[0120] In this embodiment, a first nozzle is configured by the
hydrogen supply nozzle 8b provided with a plurality of nozzles each
having a different length, and a first gas ejection hole is
configured by gas ejection holes provided in the hydrogen supply
nozzles 8b installed as many as at least the process wafers so they
correspond to at least the respective process wafers. In addition,
a second nozzle is configured by the oxygen supply nozzle 8a
provided with a single multi-hole nozzle, and a second gas ejection
hole is configured by gas ejection holes provided in the oxygen
supply nozzles 8a installed as many as at least the process wafers
so that they correspond to at least the respective process wafers.
That is, in this embodiment, both the gas ejection holes of the
hydrogen supply nozzle 8b and the gas ejection holes of the oxygen
supply nozzle 8a are installed as many as at least the process
wafers so that they correspond to at least the respective process
wafers.
[0121] In this embodiment, the arrangement pitch of the gas
ejection holes provided in the hydrogen supply nozzle 8b is set to
be equal to the wafer arrangement pitch and also set to be equal to
the arrangement pitch of the gas ejection holes provided in the
oxygen supply nozzle 8a. In addition, the respective distances
between the respective gas ejection holes provided in the hydrogen
supply nozzle 8b and the respective wafers corresponding to the
respective gas ejection holes in the wafer arrangement direction
are set to be equal to one another. The respective distances
between the respective gas ejection holes provided in the oxygen
supply nozzle 8a and the respective wafers corresponding to the
respective gas ejection holes in the wafer arrangement direction
are set to be equal to one another. Moreover, the number of the gas
ejection holes provided in the hydrogen supply nozzle 8b is set to
be equal to the number of the gas ejection holes provided in the
oxygen supply nozzle 8a. The gas ejection holes provided in the
hydrogen supply nozzle 8b are in 1:1 correspondence with the gas
ejection holes provided in the oxygen supply nozzle 8a. The
plurality of gas ejection holes provided in the hydrogen supply
nozzle 8b and the plurality of gas ejection holes provided in the
oxygen supply nozzle 8a are installed at the same heights,
respectively.
[0122] According to this embodiment, since both of H.sub.2 gas and
O.sub.2 gas are supplied to all the process wafers from the supply
points having the same position relationship, the concentration
difference caused by the existence/nonexistence of the H.sub.2 gas
supply points in the third embodiment can be removed (influence on
the intra-wafer film thickness uniformity is less), and thus, more
excellent intra-wafer and inter-wafer film thickness uniformity can
be obtained. While the processing quality necessary for the actual
state is sufficiently satisfied in the oxidation furnace described
above in third embodiment, more excellent intra-wafer and
inter-wafer film thickness uniformity can be obtained in this
embodiment.
[0123] In this embodiment, like the third embodiment, the oxidation
process may be performed by using only the sub-nozzle, without
using the main nozzle. That is, the oxidation process may be
performed by supplying O.sub.2 gas and H.sub.2 gas from only the
sub-nozzle (oxygen supply nozzle 8a, hydrogen supply nozzle 8b),
without supplying O.sub.2 gas and H.sub.2 gas from the main nozzle
7 (oxygen supply nozzle 7a, hydrogen supply nozzle 7b).
[0124] Additionally, in this embodiment, like the third embodiment,
the oxidation process may be performed even though one of O.sub.2
gas and H.sub.2 gas is supplied from the main nozzle. That is, the
oxidation process may be performed by supplying H.sub.2 gas from
the hydrogen supply nozzle 7b as the main nozzle and supplying
O.sub.2 gas and H.sub.2 gas from the sub-nozzle (oxygen supply
nozzle 8a, hydrogen supply nozzle 8b), without supplying O.sub.2
gas from the oxygen supply nozzle 7a as the main nozzle. In
addition, the oxidation process may be performed by supplying
O.sub.2 gas from the oxygen supply nozzle 7a as the main nozzle and
supplying O.sub.2 gas and H.sub.2 gas from the sub-nozzle (oxygen
supply nozzle 8a, hydrogen supply nozzle 8b), without supplying
H.sub.2 gas from the hydrogen supply nozzle 7b as the main
nozzle.
[0125] According to the present invention, there are provided a
substrate processing apparatus, which is capable of improving the
intra-wafer film thickness uniformity by suppressing the
intra-wafer film thickness distribution from being the
center-concave () distribution, while maintaining the inter-wafer
film thickness uniformity, and a method of manufacturing a
semiconductor device, which includes a process of processing a
substrate by using the substrate processing apparatus.
[0126] The disclosures of Japanese Patent Application No.
2008-13372, filed on May 22, 2008, and International Patent
Application No. PCT/JP2009/056107, filed Mar. 26, 2009, including
specification, claim, drawing, and abstract, are incorporated
herein by reference in their entirety.
Preferred Embodiments of the Present Invention
[0127] Hereinafter, preferred embodiments of the present invention
will be complementarily noted.
[0128] According to an embodiment, there is provided a substrate
processing apparatus including: a reaction tube configured to
process a plurality of substrates; a heater configured to heat the
inside of the reaction tube; a holder configured to arrange and
hold the plurality of substrates within the reaction tube; a first
nozzle disposed in an area corresponding to a substrate arrangement
area where the plurality of substrates are arranged, and configured
to supply hydrogen-containing gas from a plurality of locations of
the area into the reaction tube; a second nozzle disposed in the
area corresponding to the substrate arrangement area, and
configured to supply oxygen-containing gas from a plurality of
locations of the area into the reaction tube; an exhaust outlet
configured to exhaust the inside of the reaction tube; and a
pressure controller configured to control pressure inside the
reaction tube to be lower than atmospheric pressure, wherein the
first nozzle is provided with a plurality of first gas ejection
holes, and the second nozzle is provided with as many second gas
ejection holes as at least the plurality of substrates so that the
second gas ejection holes correspond to at least the respective
substrates.
[0129] Preferably, the second gas ejection holes are configured to
eject oxygen-containing gas to the respective substrates at a
uniform flow rate.
[0130] Preferably, the respective second gas ejection holes and the
respective substrates corresponding to the second gas ejection
holes are configured at regular distances in a substrate
arrangement direction.
[0131] Preferably, an arrangement pitch of the second gas ejection
holes is equal to an arrangement pitch of the substrates.
[0132] Preferably, the number of the first gas ejection holes is
smaller than the number of the second gas ejection holes.
[0133] Preferably, the first gas ejection holes are installed as
many as at least the plurality of substrates so that the first gas
ejection holes are in 1:1 correspondence with the plurality of
substrates.
[0134] Preferably, an arrangement pitch of the first gas ejection
holes is equal to an arrangement pitch of the substrates.
[0135] Preferably, the respective first gas ejection holes and the
respective substrates corresponding to the first gas ejection holes
are configured at regular distances in a substrate arrangement
direction.
[0136] Preferably, the number of the first gas ejection holes is
equal to the number of the second gas ejection holes.
[0137] Preferably, the first gas ejection holes are in 1:1
correspondence with the second gas ejection holes.
[0138] According to another embodiment, there is provided a method
of manufacturing a semiconductor device, including: loading a
plurality of substrates into a reaction tube; processing the
plurality of substrates by supplying hydrogen-containing gas and
oxygen-containing gas into the reaction tube, which is in a heated
state, with pressure inside the reaction tube being lower than
atmospheric pressure, respectively through a first nozzle and a
second nozzle disposed in an area corresponding to a substrate
arrangement area where the plurality of substrates are arranged;
and unloading the plurality of processed substrates from the
reaction tube, wherein when the substrates are processed, the
hydrogen-containing gas is supplied into the reaction tube from a
plurality of locations of the area corresponding to the substrate
arrangement area through a plurality of first gas ejection holes
installed in the first nozzle and, at the same time, the
oxygen-containing gas is supplied into the reaction tube from a
plurality of locations of the area corresponding to the substrate
arrangement area through second gas ejection holes installed as
many as at least the plurality of substrates in the second nozzle
so that the second gas ejection holes are in 1:1 correspondence
with at least the plurality of substrates.
* * * * *