U.S. patent application number 09/963665 was filed with the patent office on 2002-05-09 for semiconductor device manufacturing method and substrate processing apparatus.
Invention is credited to Ohoka, Tsukasa, Sano, Atsushi.
Application Number | 20020055254 09/963665 |
Document ID | / |
Family ID | 18778129 |
Filed Date | 2002-05-09 |
United States Patent
Application |
20020055254 |
Kind Code |
A1 |
Sano, Atsushi ; et
al. |
May 9, 2002 |
Semiconductor device manufacturing method and substrate processing
apparatus
Abstract
A semiconductor device manufacturing method is obtained which is
capable of depositing a ruthenium film with excellent homogeneity
in the film quality and excellent reproducibility of the surface
morphology. The semiconductor device manufacturing method of the
present invention includes heating a silicon wafer up to a
temperature of 290-350.degree. C. by means of a heater, supplying
an N.sub.2 gas to the reaction chamber thereby to hold the pressure
in the reaction chamber at a level of 60-4,000 Pa, supplying to the
reaction chamber a raw material gas containing ruthenium while
decreasing the amount of supply of the N.sub.2 gas, thereby to hold
the pressure in the reaction chamber at a level of 60-4,000 Pa,
supplying to the reaction chamber an oxygen-containing gas
containing oxygen after the amount of supply of the raw material
gas becomes constant while decreasing the amount of supply of the
N.sub.2 gas so as to hold the pressure in the reaction chamber at a
level of 60-4,000 Pa, decreasing the amount of supply of the
oxygen-containing gas after a ruthenium film is deposited,
decreasing the amount of supply of the raw material gas so as to
stop the supply of the oxygen-containing gas and the supply of the
raw material gas, and increasing the amount of supply of the
N.sub.2 gas thereby to hold the pressure in the reaction chamber at
a level of 60-4,000 Pa.
Inventors: |
Sano, Atsushi; (Tokyo,
JP) ; Ohoka, Tsukasa; (Tokyo, JP) |
Correspondence
Address: |
MCGINN & GIBB, PLLC
8321 OLD COURTHOUSE ROAD
SUITE 200
VIENNA
VA
22182-3817
US
|
Family ID: |
18778129 |
Appl. No.: |
09/963665 |
Filed: |
September 27, 2001 |
Current U.S.
Class: |
438/674 ;
257/E21.011; 257/E21.17 |
Current CPC
Class: |
H01L 21/28556 20130101;
C23C 16/45557 20130101; C23C 16/18 20130101; H01L 28/60
20130101 |
Class at
Publication: |
438/674 |
International
Class: |
H01L 021/44 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 28, 2000 |
JP |
2000-295753 |
Claims
What is claimed is:
1. A semiconductor device manufacturing method in which a ruthenium
film is formed on a substrate by using a raw material gas
containing ruthenium and an oxygen-containing gas containing
oxygen, characterized by controlling an oxygen ratio before the
start of deposition of said ruthenium film or after the end of
deposition thereof to be smaller than an oxygen ratio at the time
of deposition thereof.
2. A semiconductor device manufacturing method in which a ruthenium
film is formed on a substrate by using a raw material gas
containing ruthenium and an oxygen-containing gas containing
oxygen, characterized by controlling an oxygen ratio before the
start of deposition of said ruthenium film or after the end of
deposition thereof to be not greater than a value at which there
takes place no deposition reaction.
3. The semiconductor device manufacturing method as set forth in
claim 1, characterized by supplying said raw material gas earlier
than said oxygen-containing gas before the start of deposition of
said ruthenium film.
4. The semiconductor device manufacturing method as set forth in
claim 2, characterized by supplying said raw material gas earlier
than said oxygen-containing gas before the start of deposition of
said ruthenium film.
5. The semiconductor device manufacturing method as set forth in
claim 1, characterized by gradually increasing the amount of supply
of said oxygen-containing gas before the start of deposition when
said raw material gas and said oxygen-containing gas are supplied
at the same time before the start of deposition of said ruthenium
film.
6. The semiconductor device manufacturing method as set forth in
claim 2, characterized by gradually increasing the amount of supply
of said oxygen-containing gas before the start of deposition when
said raw material gas and said oxygen-containing gas are supplied
at the same time before the start of deposition of said ruthenium
film.
7. The semiconductor device manufacturing method as set forth in
claim 1, characterized by controlling the amount of supply of said
oxygen-containing gas before the start of deposition to be smaller
than the amount of supply of said oxygen-containing gas at the time
of deposition, or controlling the amount of supply of said
oxygen-containing gas before the start of deposition to be not
greater than a value at which there takes place no deposition
reaction, when said oxygen-containing gas is supplied prior to the
supply of said raw material gas before the start of deposition of
said ruthenium film.
8. The semiconductor device manufacturing method as set forth in
claim 2, characterized by controlling the amount of supply of said
oxygen-containing gas before the start of deposition to be smaller
than the amount of supply of said oxygen-containing gas at the time
of deposition, or controlling the amount of supply of said
oxygen-containing gas before the start of deposition to be not
greater than a value at which there takes place no deposition
reaction, when said oxygen-containing gas is supplied prior to the
supply of said raw material gas before the start of deposition of
said ruthenium film.
9. The semiconductor device manufacturing method as set forth in
claim 1, characterized by stopping the supply of said
oxygen-containing gas earlier than the supply of said raw material
gas after the end of deposition of said ruthenium film.
10. The semiconductor device manufacturing method as set forth in
claim 2, characterized by stopping the supply of said
oxygen-containing gas earlier than the supply of said raw material
gas after the end of deposition of said ruthenium film.
11. The semiconductor device manufacturing method as set forth in
claim 1, characterized by gradually decreasing the amount of supply
of said oxygen-containing gas after the end of deposition when the
supply of said raw material gas and the supply of said
oxygen-containing gas are stopped at the same time after the end of
deposition of said ruthenium film.
12. The semiconductor device manufacturing method as set forth in
claim 2, characterized by gradually decreasing the amount of supply
of said oxygen-containing gas after the end of deposition when the
supply of said raw material gas and the supply of said
oxygen-containing gas are stopped at the same time after the end of
deposition of said ruthenium film.
13. The semiconductor device manufacturing method as set forth in
claim 1, characterized by controlling the amount of supply of said
oxygen-containing gas after the end of deposition to be smaller
than the amount of supply of said oxygen-containing gas at the time
of deposition, or controlling the amount of supply of said
oxygen-containing gas after the end of deposition to be not greater
than a value at which there takes place no deposition reaction,
when the supply of said raw material gas is stopped earlier than
the supply of said oxygen-containing gas after the end of
deposition of said ruthenium film.
14. The semiconductor device manufacturing method as set forth in
claim 2, characterized by controlling the amount of supply of said
oxygen-containing gas after the end of deposition to be smaller
than the amount of supply of said oxygen-containing gas at the time
of deposition, or controlling the amount of supply of said
oxygen-containing gas after the end of deposition to be not greater
than a value at which there takes place no deposition reaction,
when the supply of said raw material gas is stopped earlier than
the supply of said oxygen-containing gas after the end of
deposition of said ruthenium film.
15. The semiconductor device manufacturing method as set forth in
claim 1, characterized by introducing a gas, which does not
contribute to deposition reactions, before the start of deposition
of said ruthenium film or after the end of deposition thereof, and
holding substantially constant the pressures before the start of
deposition, at the time of deposition and after the end of
deposition.
16. The semiconductor device manufacturing method as set forth in
claim 2, characterized by introducing a gas, which does not
contribute to deposition reactions, before the start of deposition
of said ruthenium film or after the end of deposition thereof so as
to hold substantially constant the pressures before the start of
deposition, at the time of deposition and after the end of
deposition.
17. The semiconductor device manufacturing method as set forth in
claim 1, characterized in that said raw material gas containing
ruthenium comprises a gas evaporated from
Ru(C.sub.2H.sub.5C.sub.5H.sub.4).sub.2, and that said
oxygen-containing gas containing oxygen comprises an .degree. 2
gas.
18. The semiconductor device manufacturing method as set forth in
claim 2, characterized in that said raw material gas containing
ruthenium comprises a gas evaporated from
Ru(C.sub.2H.sub.5C,H.sub.4).sub.2, and that said oxygen-containing
gas containing oxygen comprises an 02 gas.
19. A substrate processing apparatus in which a ruthenium film is
deposited on a substrate in a reaction chamber by using a raw
material gas containing ruthenium and an oxygen-containing gas
containing oxygen, characterized by comprising: an
oxygen-containing gas supply section for supplying said
oxygen-containing gas to a reaction chamber; a raw material gas
supply section for supplying said raw material gas to said reaction
chamber; and a controller for controlling said oxygen-containing
gas supply section and said raw material gas supply section in such
a manner that an oxygen ratio before the start of deposition of
said ruthenium film or after the end of deposition thereof is made
smaller than an oxygen ratio at the time of deposition thereof.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a semiconductor device
manufacturing method and a substrate processing apparatus for
depositing a ruthenium film or films on a substrate by using a raw
material gas, which contains ruthenium, and an oxygen-containing
gas, which contains oxygen.
[0003] 2. Description of the Related Art
[0004] In the past, when a ruthenium film is deposited on a silicon
wafer by a thermal CVD method by using a raw material gas
containing ruthenium and an oxygen-containing gas containing
oxygen, the oxygen-containing gas, which is the gas with a greater
flow rate of supply, is supplied prior to or earlier than the
ruthenium raw gas, which is the gas with a smaller flow rate of
supply, as illustrated in FIG. 7. (Line a represents a change in
the amount of supply of the ruthenium raw gas, and line b
represents a change in the amount of supply of the
oxygen-containing gas.) This is carried out so as to suppress
pressure fluctuations at the time of deposition. That is, the
supply of the ruthenium raw gas is started to initiate deposition
of ruthenium films after the amount of supply of the
oxygen-containing gas becomes constant. Then, after the deposition
of the ruthenium films is completed, the supply of the
oxygen-containing gas is stopped after the supply of the ruthenium
raw gas is stopped.
[0005] However, in such a gas supply method, the oxygen ratio,
i.e., the volume ratio of the oxygen-containing gas to the
ruthenium raw gas becomes greater before the start of deposition
(before time t.sub.1) and after the end of deposition (after time
t.sub.2), and hence oxygen becomes excessive so that ruthenium
oxide can be easily formed, thus impairing homogeneity or
uniformity in the film quality of the ruthenium films. Also, the
sheet resistance or the like of the ruthenium films becomes
non-uniform, and the reproducibility of the surface morphology
becomes poor, too.
SUMMARY OF THE INVENTION
[0006] The present invention is intended to obviate the problems as
referred to above, and has for its object to provide a
semiconductor device manufacturing method and a substrate
processing apparatus which is capable of depositing a ruthenium
film with excellent homogeneity in the film quality and excellent
reproducibility of the surface morphology.
[0007] In order to achieve this object, according to the present
invention, in a semiconductor device manufacturing method in which
a ruthenium film is deposited on a substrate by using a raw
material gas containing ruthenium and an oxygen-containing gas
containing oxygen, an oxygen ratio before the start of deposition
of the ruthenium film or after the end of deposition thereof is
controlled to be smaller than an oxygen ratio at the time of
deposition thereof. Incidentally, note that the oxygen ratio
referred to herein means a volume ratio of the oxygen-containing
gas to the ruthenium raw gas.
[0008] Moreover, in a semiconductor device manufacturing method in
which a ruthenium film is deposited on a substrate by using a raw
material gas containing ruthenium and an oxygen-containing gas
containing oxygen, an oxygen ratio before the start of deposition
of the ruthenium film or after the end of deposition thereof is
controlled to be not greater than a value at which there takes
place no deposition reaction.
[0009] In these cases, the raw material gas may be supplied earlier
than the oxygen-containing gas before the start of deposition of
the ruthenium film.
[0010] In addition, the amount of supply of the oxygen-containing
gas before the start of deposition may be gradually increased when
the raw material gas and the oxygen-containing gas are supplied at
the same time before the start of deposition of the ruthenium
film.
[0011] Further, the amount of supply of the oxygen-containing gas
before the start of deposition may be controlled to be smaller than
the amount of supply of the oxygen-containing gas at the time of
deposition, or the amount of supply of the oxygen-containing gas
before the start of deposition may be controlled to be not greater
than a value at which there takes place no deposition reaction.
[0012] Furthermore, the supply of the oxygen-containing gas may be
stopped earlier than the supply of the raw material gas after the
end of deposition of the ruthenium film.
[0013] Still further, the amount of supply of the oxygen-containing
gas after the end of deposition may be gradually decreased when the
supply of the raw material gas and the supply of the
oxygen-containing gas are stopped at the same time after the end of
deposition of the ruthenium film.
[0014] Besides, when the supply of the raw material gas is stopped
earlier than the supply of the oxygen-containing gas after the end
of deposition of the ruthenium film, the amount of supply of the
oxygen-containing gas after the end of deposition may be controlled
to be smaller than the amount of supply of the oxygen-containing
gas at the time of deposition, or the amount of supply of the
oxygen-containing gas after the end of deposition may be controlled
to be not greater than a value at which there takes place no
deposition reaction.
[0015] Additionally, a gas, which does not contribute to deposition
reactions, may be introduced before the start of deposition of the
ruthenium film or after the end of deposition thereof so as to hold
substantially constant the pressures before the start of
deposition, at the time of deposition and after the end of
deposition.
[0016] Moreover, the present invention may be characterized in that
the raw material gas containing ruthenium comprises a gas
evaporated from Ru(C.sub.2H.sub.5C.sub.5H.sub.4).sub.2, and that
the oxygen-containing gas containing oxygen comprises an O.sub.2
gas.
[0017] Furthermore, the present invention provides a substrate
processing apparatus in which a ruthenium film is deposited on a
substrate in a reaction chamber by using a raw material gas
containing ruthenium and an oxygen-containing gas containing
oxygen, the apparatus being characterized by comprising: an
oxygen-containing gas supply section for supplying the
oxygen-containing gas to a reaction chamber; a raw material gas
supply section for supplying the raw material gas to the reaction
chamber; and a controller for controlling the oxygen-containing gas
supply section and the raw material gas supply section in such a
manner that an oxygen ratio before the start of deposition of the
ruthenium film or after the end of deposition thereof is made
smaller than an oxygen ratio at the time of deposition thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is an explanatory view of a semiconductor device
manufacturing method according to the present invention.
[0019] FIG. 2 is an explanatory view of another semiconductor
device manufacturing method according to the present invention.
[0020] FIG. 3 is an explanatory view of a further semiconductor
device manufacturing method according to the present invention.
[0021] FIG. 4 is an explanatory view of a still further
semiconductor device manufacturing method according to the present
invention.
[0022] FIG. 5 is a cross sectional view illustrating a part of a
DRAM which includes ruthenium films deposited by using a
semiconductor device manufacturing method according to the present
invention.
[0023] FIG. 6 is a cross sectional view illustrating a
semiconductor manufacturing apparatus (substrate processing
apparatus) according to the present invention.
[0024] FIG. 7 is an explanatory view of a known semiconductor
device manufacturing method.
[0025] FIG. 8(a) is a graph illustrating the relation between the
oxygen ratio and the deposition speed, and FIG. 8(b) is a graph
illustrating the X-ray diffraction data of films deposited in areas
(A), (B) and (C) of FIG. 8(a).
[0026] FIG. 9 illustrates microphotographs representing the
reproducibility of the surface morphology according to a
semiconductor device manufacturing method of the present invention
and a known semiconductor device manufacturing method.
DESCRIPTION OF THE PREFERRED ENBODIMENTS
[0027] FIG. 6 is a cross sectional view illustrating one example of
a thermal CVD apparatus according to the present invention, that
is, a semiconductor manufacturing apparatus used when ruthenium
films are deposited on a silicon wafer in the manufacture of a
DRAM. As shown in this figure, an exhaust port 22 is provided in a
main body 21 of the apparatus, and a shower head 23 is provided at
an upper portion of the main body 21. Mounted on the main body 21
is a gas supply pipe 24 which opens into a Espace defined above the
shower head 23. Also, the gas supply pipe 24 is branched at its
upstream side into a ruthenium raw gas supply pipe 24a, which
supplies a raw material gas containing ruthenium, and an
oxygen-containing gas supply pipe 24b, which supplies an
oxygen-containing gas containing oxygen. Valves 36a and 36b are
provided on the gas supply pipes, respectively. The gas supply pipe
24a and the valve 36a together constitute a ruthenium raw gas
supply section, and the gas supply pipe 24b and the valve 36b
together constitute an oxygen-containing gas supply section. In
addition, a controller 35 is provided for the valves 36a and 36b.
The openings of the valves 36a and 36b are adjusted by this
controller 35 so that the timing of starting and stopping the gas
supplies as well as the amounts of supply of the gases are properly
controlled. Moreover, a support member 25 is mounted on the main
body 21 for vertical movement, and a base 26 is attached to the
support member 25. A heater 27 is installed on the base 26 through
a heater electrode 28. A susceptor 29 is mounted on the support
member 25. A silicon wafer 30 is disposed on the susceptor 29 with
a cover plate 31 being placed on the support member 25.
Additionally, a reaction chamber 32 is defined in the main body 21
for processing or treating the silicon wafer 30 therein.
Incidentally, 33 in this figure designates a substrate
transportation opening through which the silicon wafer 30 is
transported to the susceptor 29 in the main body 21.
[0028] Now, reference will be made to a method of depositing
ruthenium films on a silicon wafer by using this semiconductor
manufacturing apparatus. First of all, a silicon wafer 30 is
transported into the main body 21 through the substrate
transportation opening 33 so as to be placed on the susceptor 29
with the support member 25 having been descended to a location near
the substrate transportation opening 33, and by lifting the support
member 25, the silicon wafer 30 on the susceptor 29 is vertically
moved upward to a processing position in the reaction chamber 32
where the silicon wafer 30 is heated up to a processing temperature
by means of the heater 27. Subsequently, a raw material gas
containing ruthenium is supplied to the reaction chamber 32 by the
gas supply pipes 24a and 24 through the space above the shower head
23 and the shower head 23 itself, and when the amount of the
ruthenium raw gas thus supplied becomes constant or steady, an
oxygen-containing gas containing oxygen is supplied from the gas
supply pipe 24b. In this case, the ruthenium raw gas is mixed with
the oxygen-containing gas in the piping, and thereafter supplied
onto the silicon wafer 30 through the shower head 23, whereby the
oxygen in the oxygen-containing gas chemically reacts with the
ruthenium raw gas, thus depositing ruthenium films on the silicon
wafer 30. Subsequently, the supply of the oxygen-containing gas is
stopped, and the supply of the ruthenium raw gas is then stopped.
The reaction chamber 32 is purged by an inert gas such as an
N.sub.2 gas, etc. After the residual gas has been removed, the
support member 25 is downwardly moved to descend the processed
silicon wafer 30 to a wafer transportation position, where the
wafer is taken out or removed from the apparatus through the
substrate transportation opening 33.
[0029] Next, reference will be made to the timing of supplying the
gases, which is characteristic of the semiconductor device
manufacturing method according to the present invention, while
referring to FIG. 1. First, as described above, the silicon wafer
30 disposed on the susceptor 29 in the semiconductor manufacturing
apparatus is lifted to the deposition position in the reaction
chamber 32, where the silicon wafer 30 is heated up to a
temperature of 290-350.degree. C. by means of the heater 27.
Subsequently, an N.sub.2 gas, which does not contribute to
deposition reactions, is supplied to the reaction chamber in an
amount of k sccm. Here, note that the amount of the gas supply k
sccm is an amount of supply by which the pressure in the reaction
chamber 32 can be held in a range of 60-180 Pa. Then, the amount of
the N.sub.2 gas supplied is adjusted to a range of 1,250-1,500
sccm, and the pressure in the reaction chamber 32 is raised to a
value ranging from 60 to 4,000 Pa. Thereafter, a raw material gas
containing ruthenium such as, for example, a gas evaporated from a
liquid raw material Ru(C.sub.2H.sub.5C.sub.5H.sub.4).su-
b.2(referred to as bisethyl-cyclopentadienyl-ruthenium), is
supplied from the ruthenium raw gas supply pipe 24a to the reaction
chamber 32 in an amount of supply ranging from 0.005 to 0.12 sccm
while decreasing the amount of supply of the N.sub.2 gas, thereby
holding the pressure in the reaction chamber 32 at a range of
60-4,000 Pa. Subsequently, after the amount of supply of the
ruthenium raw gas has become constant or steady, an
oxygen-containing gas containing oxygen such as, for instance, an
O.sub.2 gas, is supplied to the reaction chamber from the
oxygen-containing gas supply pipe 24b in an amount of supply
ranging from 40 to 1,500 sccm while decreasing the amount of supply
of the N.sub.2 gas to a value ranging from 0 to 710 sccm, thereby
holding the pressure in the reaction chamber 32 in a range of
60-4,000 Pa. Here, note that an O.sub.3 gas or an N.sub.2O gas may
be used as the oxygen-containing gas. In this manner, the
deposition of ruthenium films is initiated. That is, the ruthenium
raw gas is supplied prior to or earlier than the oxygen-containing
gas, so that the oxygen ratio, i.e., the volume ratio of the
oxygen-containing gas to the ruthenium raw gas, before the start of
deposition of the ruthenium films is controlled to be smaller than
the oxygen ratio at the time of deposition, and not greater than a
value at which there takes place no deposition reaction in which
ruthenium is separated from the ruthenium raw gas. Then, the amount
of the oxygen-containing gas to be supplied is decreased, and
thereafter the amount of the ruthenium raw gas to be supplied is
also decreased. Thus, after the supply of the oxygen-containing gas
is stopped, the supply of the ruthenium raw gas is also stopped,
and the amount of the N.sub.2 gas to be supplied is increased to a
value ranging from 1,250 to 1,500 sccm, thereby holding the
pressure in the reaction chamber 32 at a value ranging from 60 to
4,000 Pa. In this manner, the deposition of the ruthenium films is
completed. After this, the amount of the N.sub.2 gas to be supplied
is decreased to a value of k sccm, whereby the pressure in the
reaction chamber 32 is held at a level in the range of 60-180
Pa.
[0030] In this semiconductor device manufacturing method, the
oxygen ratio before the start of deposition of ruthenium films is
smaller than the oxygen ratio at the time of deposition and not
greater than the value at which there occurs no deposition reaction
in which ruthenium is separated from the ruthenium raw gas, so that
there is deposited no ruthenium oxide, and hence the ruthenium
films with excellent homogeneity in the film quality can be
deposited, whereby it is possible to make uniform the sheet
resistance or the like of the ruthenium films, and at the same time
deposit the ruthenium films with excellent reproducibility of the
surface morphology thereof. In addition, by supplying an N.sub.2
gas, which is an inert gas not contributing to deposition
reactions, and controlling the amount of supply thereof, before the
start of deposition of ruthenium films, or after the end of
deposition thereof, or during deposition thereof, the pressure in
the reaction chamber before the start of deposition, during
deposition and after the end of the deposition is held at a
constant value in the range of 60-4,000 Pa, so that the pressure
stability after the start of supply of the ruthenium raw gas can be
easily improved, thus making it possible to stabilize the pressure
during the deposition. Consequently, the ruthenium films with
excellent homogeneity in the film quality can be deposited.
Moreover, since the pressure can be stabilized before deposition,
the stabilization in the control of pressure can be performed
without using an expensive ruthenium raw gas.
[0031] Now, reference will be made to another semiconductor device
manufacturing method according to the present invention while
referring to FIG. 2. (Line a represents a change in the amount of
supply of the ruthenium raw gas, and line b represents a change in
the amount of supply of the oxygen-containing gas.) First of all, a
silicon wafer 30 disposed on the susceptor 29 in the semiconductor
manufacturing apparatus is upwardly moved to the deposition
position in the reaction chamber 32, where the silicon wafer 30 is
heated up by the heater 27 to a temperature in the range of
290-350.degree. C. Then, a ruthenium raw gas is started to be
supplied to the reaction chamber 32, and after the amount of supply
of the ruthenium raw gas becomes constant, an oxygen-containing gas
is started to be supplied to the reaction chamber 32, thus
initiating the deposition of ruthenium films. After the deposition
of the ruthenium films has been completed, the supply of the
oxygen-containing gas to the reaction chamber 32 is ended, and
thereafter the supply of the ruthenium raw gas to the reaction
chamber 32 is also finished. That is, before the start of
deposition of the ruthenium films (before time t.sub.1), the
ruthenium raw gas is supplied to the reaction chamber prior to or
earlier than the supply of the oxygen-containing gas, and the
supply of the oxygen-containing gas is stopped earlier than the
supply of the ruthenium raw gas after the end of deposition of the
ruthenium films (after time t.sub.2), whereby the oxygen ratio
before the start of deposition of the ruthenium films and the
oxygen ratio after the end of deposition thereof are made smaller
than the oxygen ratio during the deposition, and not greater than a
value at which there takes place no deposition reaction.
[0032] In such a semiconductor device manufacturing method, since
the oxygen ratios before the start of deposition of the ruthenium
films and after the end of deposition thereof are smaller than the
oxygen ratio at the time of deposition and not greater than the
value at which there takes place no deposition reaction, there is
deposited no ruthenium oxide, and hence the ruthenium films with
excellent homogeneity in the film quality can be deposited, whereby
it is possible to make uniform the sheet resistance or the like of
the ruthenium films, and at the same time deposit the ruthenium
films with excellent reproducibility of the surface morphology
thereof.
[0033] Now, reference will be made to a further semiconductor
device manufacturing method according to the present invention
while referring to FIG. 3. (Line a represents a change in the
amount of supply of the ruthenium raw gas, and line b represents a
change in the amount of supply of the oxygen-containing gas.) First
of all, a silicon wafer 30 disposed on the susceptor 29 in the
semiconductor manufacturing apparatus is upwardly moved to the
deposition position in the reaction chamber 32, where the silicon
wafer 30 is heated up by the heater 27 to a temperature in the
range of 290-350.degree. C. Then, a ruthenium raw gas and an
oxygen-containing gas are started to be supplied to the reaction
chamber 32 at the same time. In this case, the amount of supply of
the ruthenium raw gas is made constant earlier than that of the
oxygen-containing gas, and the amount of supply of the
oxygen-containing gas is made constant after the amount of supply
of the ruthenium raw gas becomes constant, whereby the deposition
of ruthenium films is started. Incidentally, note that the amount
of supply of the oxygen-containing gas is gradually increased from
the start of the supply until the time when the amount of supply of
the oxygen-containing gas becomes constant. Then, after the
deposition of the ruthenium films is completed, the supply of the
ruthenium raw gas and the supply of the oxygen-containing gas to
the reaction chamber are ended at the same time. In this case, the
amount of supply of the oxygen-containing gas is gradually
decreased before the supplies of the ruthenium raw gas and the
oxygen-containing gas to the reaction chamber are stopped. That is,
the raw material gas and the oxygen-containing gas are supplied at
the same time before the start of deposition of the ruthenium films
(before time t.sub.1), and the amount of supply of the
oxygen-containing gas before the start of deposition is gradually
increased linearly, whereas the amount of supply of the
oxygen-containing gas is gradually decreased linearly after the end
of deposition of the ruthenium films (after time t.sub.2), and the
supply of the raw material gas and the supply of the
oxygen-containing gas are stopped at the same time.
[0034] In this semiconductor device manufacturing method, too,
since the oxygen ratios before the start of deposition of the
ruthenium films and after the end of deposition thereof are smaller
than the oxygen ratio at the time of deposition and not greater
than the value at which there takes place no deposition reaction,
there is deposited no ruthenium oxide, and hence it is possible to
deposit the ruthenium films with excellent homogeneity in the film
quality, and at the same time deposit the ruthenium films with
excellent reproducibility of the surface morphology thereof.
[0035] Now, reference will be made to a still further semiconductor
device manufacturing method according to the present invention
while referring to FIG. 4. (Line a represents a change in the
amount of supply of the ruthenium raw gas, and line b represents a
change in the amount of supply of the oxygen-containing gas.) First
of all, a silicon wafer 30 disposed on the susceptor 29 in the
semiconductor manufacturing apparatus is upwardly moved to the
deposition position in the reaction chamber 32, where the silicon
wafer is heated up by the heater 27 to a temperature in the range
of 290-350.degree. C. Then, an oxygen-containing gas is first
started to be supplied to the reaction chamber 32, and after the
amount of supply of the oxygen-containing gas becomes constant or
steady, a ruthenium raw gas is started to be supplied to the
reaction chamber 32. In this case, the amount of supply of the
oxygen-containing gas is made slight (to such an extent as not to
cause deposition reactions). Subsequently, after the amount of
supply of the ruthenium raw gas becomes constant, the amount of
supply of the oxygen-containing gas is increased to start the
deposition of ruthenium films. After the deposition of the
ruthenium films has been completed, the amount of supply of the
oxygen-containing gas to the reaction chamber 32 is decreased so
that the amount of supply of the oxygen-containing gas is made
constant. In this case, the amount of supply of the
oxygen-containing gas is made slight (to such an extent as not to
cause deposition reactions). Then, the supply of the ruthenium raw
gas is stopped, and thereafter the supply of the oxygen-containing
gas to the reaction chamber 32 is also stopped. That is, before the
start of deposition of the ruthenium films (before time t.sub.1),
the oxygen-containing gas is supplied earlier than the ruthenium
raw gas, and the amount of supply of the oxygen-containing gas
before the start of deposition is made smaller than the amount of
supply of the oxygen-containing gas during the deposition and not
greater than a value at which there takes place no deposition
reaction. In addition, after the end of deposition of the ruthenium
films (after time t.sub.2), the amount of supply of the
oxygen-containing gas is made smaller than the amount of supply of
the oxygen-containing gas at the time of deposition, and not
greater than a value at which there takes place no deposition
reaction, and the supply of the ruthenium raw gas is stopped
earlier than the supply of the oxygen-containing gas.
[0036] In this semiconductor device manufacturing method, too,
since the oxygen ratios before the start of deposition of the
ruthenium films and after the end of deposition thereof are smaller
than the oxygen ratio at the time of deposition and not greater
than the value at which there takes place no deposition reaction,
there is deposited no ruthenium oxide, and hence it is possible to
deposit the ruthenium films with excellent homogeneity in the film
quality, and at the same time deposit the ruthenium films with
excellent reproducibility of the surface morphology thereof.
[0037] FIG. 8(a) is a graph in which the relation between the
oxygen ratio and the deposition speed is illustrated. Also, FIG.
8(b) is a graph in which the X-ray diffraction data of ruthenium
films deposited in areas (A), (B) and (C) of FIG. 8(a) are
illustrated. As is clear from these graphs, a ruthenium film is
deposited in the area (A) where the deposition speed is
substantially stable. In addition, in the area (B) where the
deposition speed is high, there is deposited a mixed crystal film
composed of ruthenium and ruthenium oxide (RuO.sub.2). Moreover, in
the area (C) where the amount of change in the deposition speed is
large, there is deposited a ruthenium oxide film. Accordingly, in
order to obtain a pure ruthenium film, it is necessary to set the
oxygen ratio, i.e., the volume ratio of the oxygen-containing gas
to the ruthenium raw gas, during the deposition in such a manner
that it falls within the range of area (A). Additionally, it is
necessary to make the oxygen ratio so as not to exceed this range
even before the start of the deposition and after the end of the
deposition, and to this end, the method as explained with reference
to FIG. 1 or FIG. 2 or FIG. 3 or FIG. 4 of the present invention
will be effective.
[0038] Moreover, FIG. 9 illustrates microphotographs representing
the reproducibility of the surface morphology of ruthenium films
when a plurality (four times) of depositions were carried out by a
semiconductor device manufacturing method of the present invention
and a known semiconductor device manufacturing method,
respectively, wherein the sheet resistance values in the respective
cases are shown. As is clear from these microphotographs, the
method of the present invention is more excellent in the
reproducibility of the surface morphology than the known method.
That is, the change in the surface condition of the ruthenium film
in each of the plurality of depositions of the ruthenium film is
limited (stable) in case of the present invention, whereas the
surface condition of the ruthenium film in each of the plurality of
depositions of the ruthenium film changed greatly in case of the
known method. Further, the present invention is more excellent in
the reproducibility of the sheet resistance than the known method.
That is, the change in the value of the sheet resistance of the
ruthenium film in each of the plurality of depositions of the
ruthenium film is limited (stable) in case of the present
invention, whereas the value of the sheet resistance of the
ruthenium film in each of the plurality of depositions of the
ruthenium film changes greatly in case of the known method.
[0039] Incidentally, in the embodiment as explained with reference
to FIG. 2, before the start of deposition, the ruthenium raw gas is
supplied to the reaction chamber earlier than the oxygen-containing
gas, whereas after the end of deposition of the ruthenium films,
the supply of the oxygen-containing gas is stopped earlier than the
supply of the ruthenium raw gas; and in the embodiment as explained
with reference to FIG. 3, before the start of deposition of the
ruthenium films, the ruthenium raw gas and the oxygen-containing
gas are supplied to the reaction chamber at the same time, whereas
after the end of deposition of the ruthenium films, the supply of
the ruthenium raw gas and the supply of the oxygen-containing gas
are stopped at the same time; and in the embodiment as explained
with reference to FIG. 4, before the start of deposition of the
ruthenium films, the oxygen-containing gas is supplied earlier than
the ruthenium raw gas, whereas after the end of deposition of the
ruthenium films, the supply of the ruthenium raw gas is stopped
earlier than the supply of the oxygen-containing gas. However, the
methods of starting the supply of the ruthenium raw gas and the
supply of the oxygen-containing gas before the start of deposition
of the ruthenium films, and the methods of stopping the supply of
the ruthenium raw gas and the supply of the oxygen-containing gas
after the end of deposition of the ruthenium films may be
arbitrarily combined with one another. For instance, before the
start of deposition of the ruthenium films, the raw material gas
may be supplied to the reaction chamber earlier than the
oxygen-containing gas, as shown in FIG. 2, and after the end of
deposition of the ruthenium films, the supply of the ruthenium raw
gas and the supply of the oxygen-containing gas may be stopped at
the same time, as shown in FIG. 3. Also, before the start of
deposition of the ruthenium films, the ruthenium raw gas may be
supplied to the reaction chamber earlier than the oxygen-containing
gas, as shown in FIG. 2, and after the end of deposition of the
ruthenium films, the supply of the ruthenium raw gas may be stopped
earlier than the supply of the oxygen-containing gas, as shown in
FIG. 4. Moreover, before the start of deposition of the ruthenium
films, the ruthenium raw gas and the oxygen-containing gas are
supplied to the reaction chamber at the same time as shown in FIG.
3, and after the end of deposition of the ruthenium films, the
supply of the oxygen-containing gas may be stopped earlier than the
supply of the ruthenium raw gas, as shown in FIG. 2. In addition,
before the start of deposition of the ruthenium films, the
ruthenium raw gas and the oxygen-containing gas are supplied to the
reaction chamber at the same time, as shown in FIG. 3, and after
the end of deposition of the ruthenium films, the supply of the
ruthenium raw gas may be stopped earlier than the supply of the
oxygen-containing gas, as shown in FIG. 4. Further, before the
start of deposition of the ruthenium films, the oxygen-containing
gas is supplied earlier than the ruthenium raw gas, as shown in
FIG. 4, and after the end of deposition of the ruthenium films, the
supply of the oxygen-containing gas may be stopped earlier than the
supply of the ruthenium raw gas, as shown in FIG. 2. Furthermore,
before the start of deposition of the ruthenium films, the
oxygen-containing gas is supplied earlier than the ruthenium raw
gas, as shown in FIG. 4, and after the end of deposition of the
ruthenium films, the supply of the ruthenium raw gas and the supply
of the oxygen-containing gas are stopped at the same time, as shown
in FIG. 3. Further, in the embodiment as explained with reference
to FIG. 3, the amount of supply of the oxygen-containing gas before
the start of deposition is gradually increased linearly, and the
amount of supply of the oxygen-containing gas after the end of
deposition is gradually decreased linearly, but instead, the amount
of supply of the oxygen-containing gas before the start of
deposition may be gradually increased stepwise, and the amount of
supply of the oxygen-containing gas after the end of deposition may
be gradually decreased stepwise. In addition, although in the
above-mentioned embodiments, the explanation has been made of the
case where the substrate is comprised of a silicon wafer, the
present invention is also applicable to the case where ruthenium
films are deposited on another substrate. Moreover, although in
each of the embodiments as explained with reference to FIG. 1
through FIG. 4, the supply of the raw material gas containing
ruthenium to the reaction chamber is started after the temperature
of the silicon wafer has reached the processing temperature
(290-350.degree. C.), it is preferable that the supply of the raw
material gas containing ruthenium be started in the course of
rising in temperature of the silicon wafer. By doing so, when the
temperature of the silicon wafer reaches the processing
temperature, it is possible to create the state in which the flow
rate of the raw material gas containing ruthenium has already been
stabilized, so that deposition can be carried out quickly after a
temperature rise of the silicon wafer. For similar reasons, it is
also preferable that the introduction of the inert gas into the
reaction chamber before deposition, the adjustment of the pressure
in the reaction chamber or the like be carried out in the course of
rising in temperature of the silicon wafer.
[0040] As described in detail, in the semiconductor device
manufacturing method and the substrate processing apparatus
according to the present invention, the oxygen ratio, i.e., the
volume ratio of the oxygen-containing gas to ruthenium raw gas,
before the start of deposition of the ruthenium films or after the
end of deposition thereof, is smaller than the oxygen ratio at the
time of deposition, and the oxygen ratio before the start of
deposition of the ruthenium films or after the end of deposition
thereof is not greater than a value at which there takes place no
deposition reaction, there is deposited no ruthenium oxide, and
hence it is possible to deposit the ruthenium films with excellent
homogeneity in the film quality, and at the same time deposit the
ruthenium films with excellent reproducibility of the surface
morphology thereof.
[0041] FIG. 5 illustrates, in cross section, a part of a DRAM
including ruthenium films deposited by using a semiconductor
manufacturing method of the present invention.
[0042] As shown in this figure, on a surface of a silicon substrate
1, there are deposited field oxide films 2 for forming a multitude
of transistor-forming regions in a mutually separated manner. Also,
on the surface of the silicon substrate 1, there are formed source
electrodes 3 and drain electrodes 4 with gate electrodes 6 acting
as word lines being disposed therebetween via gate insulation films
5, respectively, on which an interlayer insulation film 7 is
provided. Contact holes 8 are formed through the interlayer
insulation film 7, and a barrier metal 9 and a plug electrode 15
connected to a corresponding one of the source electrodes 3 are
formed in each of the contact holes 8. On the interlayer insulation
film 7, there is formed another interlayer insulation film 10
through which contact holes 11 are formed. On the interlayer
insulation film 10 and in the contact holes 11, there is provided a
capacitance lower electrode 12 which is made of ruthenium, formed
by the manufacturing method of the present invention and connected
with the barrier metals 9. Formed on the capacitance lower
electrode 12 is a capacitance insulation film 13 made of
Ta.sub.2O.sub.5 on which is formed a capacitance upper electrode 14
made of ruthenium or the like according to the manufacturing method
of the present invention. Here, note that the capacitance upper
electrode 14 may be made of titanium nitride. That is, with this
DRAM, a capacitor cell is connected with the source electrode 3 of
a MOS transistor.
[0043] Next, reference will be had to a method of manufacturing the
DRAM illustrated in FIG. 5. First, a field oxide film 2 is formed
in the surroundings of each transistor-forming region on the
surface of the silicon substrate 1 by means of a LOCOS process.
Subsequently, a gate electrode 6 is formed in each
transistor-forming region through a corresponding gate insulation
layer 5. Thereafter, impurities are introduced into the surface of
the silicon substrate 1 by ion-implantation using the field oxide
films 2 and the gate electrodes 6 as masks, thus forming the source
electrodes 3 and the drain electrodes 4 in a self-aligned manner.
After each gate electrode 6 is covered with an insulating film, the
interlayer insulation film 7 is formed on the substrate 1. Then,
each contact hole 8 through which a corresponding source electrode
3 is exposed is formed through the interlayer insulation film 7,
and the plug electrode 15 and the barrier metal 9 are formed in
each contact hole 8. Subsequently, the interlayer insulation film
10 is formed on the interlayer insulation film 7, and the contact
holes 11 are formed through the interlayer insulation film 10 so as
to expose the corresponding barrier metals 9, respectively.
Thereafter, a ruthenium film is deposited on the interlayer
insulation film 10 and in the contact holes 11 by means of the
semiconductor manufacturing method of the present invention, and
patterning is effected to provide the capacitance lower electrode
12. The capacitance insulation film 13 made of Ta.sub.2O.sub.5 is
then formed on the capacitance lower electrode 12, and the
capacitance upper electrode 14 made of ruthenium, titanium nitride,
etc., is in turn formed on the capacitance insulation film 13. In
case where ruthenium is used for the capacitance upper electrode
14, deposition is carried out according to the manufacturing method
of the present invention.
* * * * *