U.S. patent application number 15/961277 was filed with the patent office on 2018-08-30 for method of manufacturing semiconductor device and substrate processing apparatus.
This patent application is currently assigned to HITACHI KOKUSAI ELECTRIC INC.. The applicant listed for this patent is HITACHI KOKUSAI ELECTRIC INC.. Invention is credited to Hiroshi ASHIHARA, Kazuhiro HARADA, Hideharu ITATANI, Yukinao KAGA, Arito OGAWA.
Application Number | 20180247819 15/961277 |
Document ID | / |
Family ID | 54368474 |
Filed Date | 2018-08-30 |
United States Patent
Application |
20180247819 |
Kind Code |
A1 |
OGAWA; Arito ; et
al. |
August 30, 2018 |
METHOD OF MANUFACTURING SEMICONDUCTOR DEVICE AND SUBSTRATE
PROCESSING APPARATUS
Abstract
Provided is a technique of adjusting a work function. A method
of manufacturing a semiconductor device includes forming a film
having a predetermined thickness and containing a first metal
element, carbon and nitrogen on a substrate by: (a) forming a first
layer containing the first metal element and carbon by supplying a
metal-containing gas containing the first metal element and a
carbon-containing gas to the substrate M times and (b) forming a
second layer containing the first metal element, carbon and
nitrogen by supplying a nitrogen-containing gas to the substrate
having the first layer formed thereon N times to nitride the first
layer, wherein M and N are selected in a manner that a work
function of the film has a predetermined value (where M and N are
natural numbers).
Inventors: |
OGAWA; Arito; (Toyama-shi,
JP) ; HARADA; Kazuhiro; (Toyama-shi, JP) ;
KAGA; Yukinao; (Toyama-shi, JP) ; ITATANI;
Hideharu; (Toyama-shi, JP) ; ASHIHARA; Hiroshi;
(Toyama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HITACHI KOKUSAI ELECTRIC INC. |
Tokyo |
|
JP |
|
|
Assignee: |
HITACHI KOKUSAI ELECTRIC
INC.
Tokyo
JP
|
Family ID: |
54368474 |
Appl. No.: |
15/961277 |
Filed: |
April 24, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14801984 |
Jul 17, 2015 |
|
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|
15961277 |
|
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|
|
PCT/JP2014/050751 |
Jan 17, 2014 |
|
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14801984 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 16/36 20130101;
H01L 29/513 20130101; H01L 21/28568 20130101; H01L 27/1085
20130101; H01L 21/28562 20130101; H01L 21/28088 20130101; C23C
16/45523 20130101; H01L 21/28194 20130101; C23C 16/45561 20130101;
C23C 16/0272 20130101; C23C 16/45578 20130101; H01L 28/40 20130101;
C23C 16/52 20130101; C23C 16/45531 20130101; C23C 16/4412 20130101;
C23C 16/405 20130101; H01L 21/28185 20130101; H01L 29/4966
20130101; H01L 29/517 20130101; C23C 16/402 20130101; H01L 21/28556
20130101; H01L 21/02181 20130101 |
International
Class: |
H01L 21/28 20060101
H01L021/28; H01L 21/02 20060101 H01L021/02; C23C 16/36 20060101
C23C016/36; C23C 16/40 20060101 C23C016/40; C23C 16/44 20060101
C23C016/44; C23C 16/455 20060101 C23C016/455; H01L 49/02 20060101
H01L049/02; H01L 27/108 20060101 H01L027/108; H01L 21/285 20060101
H01L021/285; C23C 16/02 20060101 C23C016/02; C23C 16/52 20060101
C23C016/52 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 18, 2013 |
JP |
2013-006965 |
Jan 22, 2013 |
JP |
2013-009577 |
Jan 16, 2014 |
JP |
2014-005809 |
Claims
1. A method of manufacturing a semiconductor device, comprising
forming a film having a predetermined thickness and containing a
first metal element, carbon and nitrogen on a substrate by: (a)
forming a first layer containing the first metal element and carbon
by supplying a metal-containing gas containing the first metal
element and a carbon-containing gas to the substrate M times and
(b) forming a second layer containing the first metal element,
carbon and nitrogen by supplying a nitrogen-containing gas to the
substrate having the first layer formed thereon N times to nitride
the first layer, wherein M and N are selected in a manner that a
work function of the film has a predetermined value (where M and N
are natural numbers).
2. The method of claim 1, wherein the first metal element comprises
one selected from the group consisting of tantalum, cobalt,
tungsten, molybdenum, ruthenium, yttrium, lanthanum, zirconium and
hafnium.
3. The method of claim 1, wherein the metal-containing gas
comprises one selected from the group consisting of TiCl.sub.4 and
TaCl.sub.4.
4. The method of claim 1, wherein the carbon-containing gas
comprises Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2.
5. The method of claim 1, wherein the carbon-containing gas
comprises a second metal element different from the first metal
element.
6. The method of claim 5, wherein the second metal element
comprises hafnium.
7. The method of claim 1, wherein the work function of the film is
increased by selecting M greater than N.
8. The method of claim 1, wherein a concentration of carbon in the
film is controlled by selecting M and N to adjust the work function
of the film to be the predetermined value.
9. A method of manufacturing a semiconductor device, comprising:
forming a metal film containing carbon and nitrogen in a
predetermined ratio on a substrate by: (a) forming a first layer
containing a metal element and one of carbon and nitrogen M times
and (b) forming a second layer containing the metal element,
nitrogen and carbon N times, wherein (a) and (b) are alternately
performed L times (where M, N and L are natural numbers).
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATION
[0001] This application is a divisional of U.S. patent application
Ser. No. 14/801,984 filed Jul. 17, 2015, based upon and claims the
benefit of priority from Japanese Patent Application No.
2013-006965, filed on Jan. 18, 2013, Japanese Patent Application
No. 2013-009577, filed on Jan. 22, 2013, and Japanese Patent
Application No. 2014-005809, filed on Jan. 16, 2014, in the
Japanese Patent Office, and International Application No.
PCT/JP2014/050751, filed on Jan. 17, 2014, in the WIPO, the whole
contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention relates to a method of manufacturing a
semiconductor device and a substrate processing apparatus.
2. Description of the Related Art
[0003] Recently, various metal films have been used as gate
electrodes in a gate stack structure. A representative example of a
metal gate electrode is titanium nitride (TiN). If a metal gate
electrode having a work function different from that of TiN is
required, a difficulty level of a process becomes relatively high
due to a problem such as process integration (e.g., a processing
error, thermal stability, diffusion stability, etc.) when a metal
electrode having a different work function different from that of
TiN is used. In such a scenario, there is a growing need for a
metal film having an adjustable threshold voltage Vth, i.e., a
metal film having a tunable (adjustable or modulatable) work
function, based on a process of forming a TiN film, since the metal
film has affinity with a process in terms of integration with a
technique generally used in the art. Also, as semiconductor
devices, such as a metal-oxide-semiconductor field effect
transistor (MOSFET), have been developed to have a high integration
density and high performance, various metal films are used as
electrodes, wires, etc. Among the various metal films, a metal
carbide-based metal film or a metal nitride-based metal film is
generally used as either a gate electrode or a capacitor electrode
of a dynamic random access memory (DRAM) in terms of oxidation
resistance, electric resistivity, a work function, etc.
RELATED ART DOCUMENT
Patent Document
[0004] 1. Japanese Unexamined Patent Application Publication No.
2011-216846 [0005] 2. Japanese Unexamined Patent Application
Publication No. 2011-6783
SUMMARY OF THE INVENTION
[0006] It is an objective of the present invention to provide a
technique of adjusting a work function to a desired level while
securing affinity with a process in terms of integration of a
technique generally used in the art.
[0007] According to one aspect of the present invention, a method
of manufacturing a semiconductor device includes forming a film
having a predetermined thickness and containing a first metal
element, carbon and nitrogen on a substrate by: (a) forming a first
layer containing the first metal element and carbon by supplying a
metal-containing gas containing the first metal element and a
carbon-containing gas to the substrate M times and (b) forming a
second layer containing the first metal element, carbon and
nitrogen by supplying a nitrogen-containing gas to the substrate
having the first layer formed thereon N times to nitride the first
layer, wherein M and N are selected in a manner that a work
function of the film has a predetermined value (where M and N are
natural numbers).
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic configuration diagram of a vertical
process furnace of a substrate processing apparatus according to an
embodiment of the present invention, in which a vertical sectional
view of a process furnace portion is illustrated.
[0009] FIG. 2 is a cross-sectional view of the process furnace
portion of the vertical process furnace of FIG. 1, taken along line
A-A of FIG. 1.
[0010] FIG. 3 is a schematic block diagram of a controller included
in the substrate processing apparatus of FIG. 1.
[0011] FIG. 4 illustrates a film-forming flow in a sequence of the
substrate processing apparatus of FIG. 1 according to a first
embodiment of the present invention.
[0012] FIG. 5 illustrates gas supply timing based on the sequence
of FIG. 4 according to the first embodiment.
[0013] FIG. 6 illustrates gas supply timing in a sequence according
to a second embodiment of the present invention.
[0014] FIG. 7 illustrates gas supply timing in a sequence according
to a third embodiment of the present invention.
[0015] FIG. 8 illustrates the structure of a semiconductor device
according to a fourth embodiment of the present invention.
[0016] FIG. 9 is a flowchart of a process of manufacturing a gate
of the semiconductor device of FIG. 8 according to an embodiment of
the present invention.
[0017] FIG. 10 is a flowchart of a metal-film forming process
included in the process of manufacturing the gate of FIG. 9.
[0018] FIG. 11 illustrates gas supply timing in the metal-film
forming process of FIG. 10.
[0019] FIG. 12 is a graph illustrating a ratio of C/Ti measured by
conducting an X-ray photoelectron spectroscopy (XPS) analysis on
TiCN films according to Examples 1 to 3.
[0020] FIG. 13A is a graph illustrating the concentration of carbon
(C) in the TiCN films according to Examples 1 to 3, measured by
XPS.
[0021] FIG. 13B is a graph illustrating the concentration of
nitrogen (N) in the TiCN films according to Examples 1 to 3,
measured by XPS.
[0022] FIGS. 14A to 14C illustrate the structures of capacitors
prepared for an experiment.
[0023] FIG. 15 is a graph in which data for calculating a work
function is plotted.
[0024] FIG. 16 is a graph illustrating the relationship between an
equivalent oxide thickness and a flat-band voltage with respect to
each of metal films formed according to Examples 4 to 8.
[0025] FIG. 17 is a table illustrating the relationship between a
ratio between carbon (C) and nitrogen (N) and an effective work
function of each of the metal films formed according to Examples 4
to 8.
[0026] FIG. 18A is a graph illustrating a variation in a work
function versus a ratio of carbon (C) in each of the metal films
formed according to Examples 4 to 8.
[0027] FIG. 18B is a graph illustrating a variation in a work
function versus a ratio of nitrogen (N) in each of the metal films
formed according to Examples 4 to 8.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] One of major parameters representing features of a
metal-oxide-semiconductor field effect transistor (MOSFET) is a
threshold voltage Vth. The threshold voltage Vth is determined by a
work function of an electrode. The work function of the electrode
may be tuned (adjusted or modulated) using a metal film used to
form the electrode. Work functions of a P type transistor and an N
type transistor are different from each other. The P type
transistor requires a work function of 5.0 eV or more, and the N
type transistor requires a work function of 4.3 eV or less.
However, the required work functions of the P type transistor and
the N type transistor may vary according to a purpose. In this
case, the work functions of the transistors are preferably adjusted
using one film having a same element composition. According to the
present invention, in this case, a work function may be adjusted
according to a purpose by controlling, for example, the
concentration of carbon (single-phase carbon (C)) in a TiCN film
(titanium carbonitride film) having the same element composition.
The work function may be adjusted according to a purpose by
increasing, for example, the concentration of carbon (C) to
decrease the work function.
First Embodiment
[0029] A first embodiment of the present invention will be
described based on the accompanying drawings below. FIGS. 1 and 2
illustrate a substrate processing apparatus 10 according to an
exemplary embodiment of the present invention. The substrate
processing apparatus 10 is embodied as an example of a
semiconductor manufacturing apparatus to be used to manufacture a
semiconductor device (device).
[0030] <Structure of Process Furnace>
[0031] As illustrated in FIGS. 1 and 2, a process furnace 202
includes a heater 207 serving as a heating means (a heating
mechanism or a heating system) for heating a wafer 200 which is a
substrate. The heater 207 includes a cylindrical insulating member,
the top of which is blocked, and a plurality of heater wires, and
has a unit structure in which the plurality of heater wires are
installed with respect to the insulating member. At an inner side
of the heater 207, a reaction tube 203 is installed concentrically
with the heater 207 to form a reaction container (process
container). The reaction tube 203 is formed of, for example, a
heat-resistant material such as quartz (SiO.sub.2) or silicon
carbide (SiC), and has a cylindrical shape, the top end of which is
closed and the bottom end of which is open.
[0032] A manifold formed of, for example, stainless steel, is
installed below the reaction tube 203 via an O-ring 220 which is a
sealing member. A low end opening of the manifold 209 is
air-tightly closed by a seal cap 219 which is a lid via the O-ring
220. A process chamber 201 includes at least the reaction tube 203,
the manifold 209 and the seal cap 219. On the seal cap 219, a boat
217 which is a substrate support means serving as a substrate
support means (a substrate support mechanism) is vertically
installed via a boat holder 218. The boat holder 218 includes a
holder body configured to hold the boat 217 while supporting the
boat 217.
[0033] A plurality of wafers 200 to be processed in batch are
stacked on the boat 217 in a horizontal posture and a multi-stage
manner in a tube axial direction. The boat 217 is configured to be
moved up or down to (or to access) the reaction tube 203 via a boat
elevator 115 serving as a transport means (transfer mechanism). A
boat rotating mechanism 267 is installed below the boat holder 218
to improve process uniformity. The boat 217 supported on the boat
holder 218 may be rotated by driving the boat rotating mechanism
267. The heater 207 heats wafers 200 inserted into the process
chamber 201 to a predetermined temperature.
[0034] In the process chamber 201, a nozzle 410 (first nozzle 410),
a nozzle 420 (second nozzle 420) and a nozzle 430 (third nozzle
430) are installed to pass through the bottom of the reaction tube
203. A gas supply pipe 310 (first gas supply pipe 310), a gas
supply pipe 320 (second gas supply pipe 320) and a gas supply pipe
330 (third gas supply pipe 330) serving as gas supply lines are
connected to the nozzle 410, the nozzle 420 and the nozzle 430,
respectively. As described above, in the reaction tube 203, three
nozzles 410, 420 and 430 and three gas supply pipes 310, 320 and
330 are installed to supply a plurality of types of gases (here,
three types of process gases) into the process chamber 201.
[0035] At the gas supply pipe 310, a mass flow controller (MFC) 312
which is a flow rate control device (flow rate control unit) and a
valve 314 which is an opening/closing valve are sequentially
installed from an upstream end. The nozzle 410 is connected to a
front end portion of the gas supply pipe 310. The nozzle 410 is
configured as an L-shaped long nozzle, the horizontal portion of
which passes through a sidewall of the reaction tube 203 and the
vertical portion of which is configured to move, in an arc-shaped
space between inner walls of the reaction tube 203 and the wafers
200, upward from lower inner walls of the reaction tube 203 in a
direction in which the wafers 200 are stacked (i.e., to move from
one end of a wafer arrangement region to the other end thereof).
That is, the nozzle 410 is installed in a region which horizontally
surrounds a side of the wafer arrangement region in which the
wafers 200 are arranged and is parallel to the wafer arrangement
region.
[0036] A plurality of gas supply holes 410a are formed in a side
surface of the nozzle 410 to supply a gas. The plurality of gas
supply holes 410a are open toward a center of the reaction tube
203. The plurality of gas supply holes 410a are formed from a lower
portion of the reaction tube 203 to an upper portion thereof and
each have the same opening area (or different opening areas) at the
same opening pitch. A first gas supply system mainly includes the
gas supply pipe 310, the MFC 312, the valve 314 and the nozzle
410.
[0037] A carrier gas supply pipe 510 is connected to the gas supply
pipe 310 to supply a carrier gas. At the carrier gas supply pipe
510, an MFC 512 and a valve 514 are installed. A first carrier gas
supply system mainly includes the carrier gas supply pipe 510, the
MFC 512 and the valve 514.
[0038] At the gas supply pipe 320, an MFC 322 which is a flow rate
control device (flow rate control unit) and a valve 324 which is an
opening/closing valve are sequentially installed from an upstream
end. The nozzle 420 is connected to a front end portion of the gas
supply pipe 320. The nozzle 420 is configured as an L-shaped long
nozzle, the horizontal portion of which passes through a sidewall
of the manifold 209 and the vertical portion of which is configured
to move, in the arc-shaped space between the inner walls of the
reaction tube 203 and the wafers 200, upward from the lower inner
walls of the reaction tube 203 in the direction in which the wafers
200 are stacked (i.e., to move from one end of the wafer
arrangement region to another end thereof). That is, the nozzle 420
is installed in a region which horizontally surrounds a side of the
wafer arrangement region in which the wafers 200 are arranged and
is parallel to the wafer arrangement region.
[0039] A plurality of gas supply holes 420a are formed in a side
surface of the nozzle 420 to supply a gas. The plurality of gas
supply holes 420a are open toward the center of the reaction tube
203. The plurality of gas supply holes 420a are formed from the
lower portion of the reaction tube 203 to the upper portion thereof
and each have the same opening area (or different opening areas) at
the same opening pitch. A second gas supply system mainly includes
the gas supply pipe 320, the MFC 322, the valve 324 and the nozzle
420.
[0040] A carrier gas supply pipe 520 is connected to the gas supply
pipe 320 to supply a carrier gas. At the carrier gas supply pipe
520, an MFC 522 and a valve 524 are installed. A second carrier gas
supply system mainly includes the carrier gas supply pipe 520, the
MFC 522 and the valve 524.
[0041] At the gas supply pipe 330, an MFC 332 which is a flow rate
control device (flow rate control unit) and a valve 334 which is an
opening/closing valve are sequentially installed from an upstream
end. The nozzle 430 is connected to a front end portion of the gas
supply pipe 330. The nozzle 430 is configured as an L-shaped long
nozzle, the horizontal portion of which passes through the sidewall
of the manifold 209 and the vertical portion of which is configured
to move, in the arc-shaped space between the inner walls of the
reaction tube 203 and the wafers 200, upward from the lower inner
walls of the reaction tube 203 in the direction in which the wafers
200 are stacked (i.e., to move from one end of the wafer
arrangement region to another end thereof). That is, the nozzle 430
is installed in a region which horizontally surrounds a side of the
wafer arrangement region in which the wafers 200 are arranged and
is parallel to the wafer arrangement region.
[0042] A plurality of gas supply holes 430a are formed in a side
surface of the nozzle 420 to supply a gas. The plurality of gas
supply holes 430a are open toward the center of the reaction tube
203. The plurality of gas supply holes 430a are formed from the
lower portion of the reaction tube 203 to the upper portion thereof
and each have the same opening area (or different opening areas) at
the same opening pitch. A third gas supply system mainly includes
the gas supply pipe 330, the MFC 332, the valve 334 and the nozzle
430.
[0043] A carrier gas supply pipe 530 is connected to the gas supply
pipe 330 to supply a carrier gas. At the carrier gas supply pipe
530, an MFC 532 and a valve 534 are installed. A third carrier gas
supply system mainly includes the carrier gas supply pipe 530, the
MFC 532 and the valve 534.
[0044] As described above, in a gas supply method according to the
present embodiment, a gas is transferred via the nozzles 410, 420
and 430 arranged in the arc-shaped space that is vertically long
and defined by the inner walls of the reaction tube 203 and end
portions of the stacked wafers 200, and is emitted into the
reaction tube 203 from the vicinity of the wafers 200 via the gas
supply holes 410a, 420b and 430c that are open in the nozzles 410,
420 and 430, thereby causing the gas to flow in the reaction tube
203 mainly in a direction parallel to surfaces of the wafers 200,
i.e., a horizontal direction. Since a gas may be uniformly supplied
onto the wafers 200 using the above structure, there is an
advantage in which a thin film is formed to have a uniform
thickness on the wafers 200. After a reaction, a residual gas flows
in a direction of an exhaust port, i.e., an exhaust pipe 231 which
will be described below but the direction in which the residual gas
flows is not limited to a vertical direction and may be
appropriately determined by the location of the exhaust port.
[0045] As an example of the above structure, for example, titanium
tetrachloride (TiCl.sub.4) which is a source gas (a titanium
(Ti)-containing source which is at least a metal-containing gas (a
metal compound) and contains the element titanium (Ti)) is supplied
as a first process gas containing a first specific element into the
process chamber 201 through the gas supply pipe 310 via the MFC
312, the valve 314 and the nozzle 410. When a liquid source, such
as TiCl.sub.4 which is in a liquid state at normal temperature and
pressure, is used, the liquid source is vaporized using a
vaporization system such as a vaporizer or a bubbler and supplied
as TiCl.sub.4 gas which is a Ti-containing gas.
[0046] Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 which is
carbon (C)-containing gas (a carbon source) that contains at least
the element carbon (C) is supplied as a second process gas
containing a second specific element, e.g., a first reactive gas,
into the process chamber 201 through the gas supply pipe 320. When
a solid source, such as
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 which is in a
solid state at normal temperature and pressure, is used, the solid
source is heated or melted with a solvent such as ethyl cyclohexane
(ECH) or tetrahydrofuran (THF) to a liquid state, and the
liquid-state source is vaporized using a vaporization system such
as a vaporizer or a bubbler and supplied as a gas.
[0047] A second reactive gas, e.g., ammonia (NH.sub.3), which is a
nitrogen (N)-containing gas that contains at least nitrogen (N) and
is a nitriding source, i.e., a nitriding gas, is supplied as a
third process gas containing a third specific element into the
process chamber 201 through the gas supply pipe 330.
[0048] For example, nitrogen (N.sub.2) gas is supplied into the
process chamber 201 through the carrier gas supply pipes 510, 520
and 530 via the MFCs 512, 522 and 532, the valve 514, 524 and 534,
the gas supply pipes 310, 320 and 330, and the nozzles 410, 420 and
430.
[0049] For example, when a gas is supplied through each of these
gas supply pipes, a source gas supply system is configured with the
first gas supply system. The source gas supply system is also
referred to as a metal-containing gas supply system. Also, a
C-containing gas supply system (carbon source supply system) is
configured with the second gas supply system. An N-containing gas
supply system (a nitriding source supply system) is configured with
the third gas supply system. When a C-containing gas and an
N-containing gas are collectively referred to as a reactive gas, a
first reactive gas supply system is configured with the
C-containing gas supply system and a second reactive gas supply
system is configured with the N-containing gas supply system. Also,
the source gas supply system, the C-containing gas supply system
and the N-containing gas supply system may be simply referred to as
a metal source supply system, a carbon source supply system, and a
nitriding source supply system, respectively.
[0050] The exhaust pipe 231 is installed at the reaction tube 203
to exhaust an atmosphere in the process chamber 201. When viewed
from a horizontal cross-section as illustrated in FIG. 2, the
exhaust pipe 231 is installed at a side opposite a side at which
the gas supply holes 410a of the nozzle 410, the gas supply holes
420a of nozzle 420 and the gas supply holes 430a of the nozzle 430
of the reaction tube 203 are formed, i.e., the exhaust pipe 231 is
installed at a side past the wafers 200 and is opposite to the gas
supply holes 410a, 420a and 430a. Also, when viewed from a vertical
cross-section as illustrated in FIG. 1, the exhaust pipe 231 is
installed below the locations of the gas supply holes 410a, 420a
and 430a. Due to the above structure, a gas supplied near the
wafers 200 in the process chamber via the gas supply holes 410a,
420a and 430a flows in a horizontal direction, i.e., a direction
parallel to surfaces of the wafer 200, flows downward, and is then
exhausted via the exhaust pipe 231. In the process chamber 201, a
gas flows mainly in the horizontal direction as described
above.
[0051] At the exhaust pipe 231, a pressure sensor 245 serving as a
pressure detector (pressure detection unit) for detecting pressure
in the process chamber 201, an auto pressure controller (APC) valve
243 serving as an exhaust valve configured as a pressure adjustor
(pressure adjustment unit), and a vacuum pump 246 serving as a
vacuum exhaust device are sequentially connected from an upstream
end. Also, a trapping device that traps reaction byproducts,
non-reacted source gas, etc. contained in an exhaust gas or a
harm-eliminating device that eliminates a corrosive substance or a
toxic substance contained in an exhaust gas may be connected to the
exhaust pipe 231. An exhaust system, i.e., an exhaust line, mainly
includes the exhaust pipe 231, the APC valve 243 and the pressure
sensor 245. The vacuum pump 246 may be further included in the
exhaust system. Also, the trapping device or the harm-eliminating
device may be further included in the exhaust system.
[0052] Vacuum exhausting may be performed or suspended in the
process chamber 201 by opening or closing the APC valve 243 while
the vacuum pump 246 is operated, and pressure in the process
chamber 201 may be controlled by adjusting a degree of openness of
the APC valve 243 while the vacuum pump 246 is operated.
[0053] In the reaction tube 203, a temperature sensor 263 is
installed as a temperature detector. The temperature in the process
chamber 201 may be controlled to have a desired temperature
distribution by controlling a current supply to be supplied to the
heater 207 based on temperature information detected by the
temperature sensor 263. The temperature sensor 263 has an L shape
similar to the nozzles 410, 420 and 430, and is installed along the
inner wall of the reaction tube 203.
[0054] A controller 121 is installed in FIG. 3. As illustrated in
FIG. 3, the controller 121 is configured as a computer including a
central processing unit (CPU) 121a, a random access memory (RAM)
121b, a memory device 121c and an input/output (I/O) port 121d. The
RAM 121b, the memory device 121c and the I/O port 121d are
configured to exchange data with the CPU 121a via an internal bus
121e. An I/O device 122 configured, for example, as a touch panel
or the like is connected to the controller 121.
[0055] The memory device 121c is configured, for example, as a
flash memory, a hard disk drive (HDD), or the like. In the memory
device 121c, a control program for controlling an operation of a
substrate processing apparatus, a process recipe including an order
or conditions of substrate processing which will be described
below, etc. are stored to be readable. The process recipe is a
combination of sequences of a substrate processing process which
will be described below to obtain a desired result when the
sequences are performed by the controller 121, and acts as a
program. Hereinafter, the process recipe, the control program, etc.
will also be collectively and simply referred to as a `program.`
When the term `program` is used in the present disclosure, it
should be understood as including only the process recipe, only the
control program, or both of the process recipe and the control
program. The RAM 121b is configured as a memory area (a work area)
in which a program or data read by the CPU 121a is temporarily
stored.
[0056] The I/O port 121d is connected to the MFCs 312, 322, 332,
512, 522 and 532, the valves 314, 324, 334, 514, 524, 534 and 614,
the pressure sensor 245, the APC valve 243, the vacuum pump 246,
the heater 207, the temperature sensor 263, the boat rotating
mechanism 267, the boat elevator 115, etc.
[0057] The CPU 121a is configured to read and execute the control
program from the memory device 121c and to read the process recipe
from the memory device 121c according to a manipulation command
received via the I/O device 122. Also, the CPU 121a is configured,
based on the read process recipe, to control flow rates of various
gases via the MFCs 312, 322, 332, 512, 522 and 532; control
opening/closing of the valves 314, 324, 334, 514, 524, 534 and 614;
control the degree of pressure by opening/closing the APC valve 243
based on the pressure sensor 245 using the APC valve 243; control
temperature of the heater 207 based on the temperature sensor 263;
control driving/suspending of the vacuum pump 246; control the
rotation and rotation speed of the boat 217 using the boat rotating
mechanism 267; control upward/downward movement of the boat 217
using the boat elevator 115, etc.
[0058] The controller 121 is not limited to a dedicated computer
and may be configured as a general-purpose computer. For example,
the controller 121 according to the present embodiment may be
configured by preparing an external memory device 123 storing a
program as described above, e.g., a magnetic disk (a magnetic tape,
a flexible disk, a hard disk, etc.), an optical disc (a compact
disc (CD), a digital versatile disc (DVD), etc.), a magneto-optical
(MO) disc, or a semiconductor memory (a Universal Serial Bus (USB)
memory, a memory card, etc.), and then installing the program in a
general-purpose computer using the external memory device 123.
Also, means for supplying a program to a computer are not limited
to using the external memory device 123. For example, a program may
be supplied to a computer using communication means, e.g., the
Internet or an exclusive line, without using the external memory
device 123. The memory device 121c or the external memory device
123 may be configured as a non-transitory computer-readable
recording medium. Hereinafter, the memory device 121c and the
external memory device 123 may also be collectively and simply
referred to as a `recording medium.` Also, when the term `recording
medium` is used in the present disclosure, it may be understood as
including only the memory device 121c, only the external memory
device 123, or both the memory device 121c and the external memory
device 123.
[0059] <Substrate Processing Process>
[0060] Next, an example of a process of forming a thin film on the
wafer 200 using the process furnace 202 of the substrate processing
apparatus described above will be described as a process included
in a process of manufacturing a semiconductor device (device). In
the following description, operations of various elements of the
substrate processing apparatus are controlled by the controller
121.
[0061] FIG. 4 illustrates a film-forming flow in an exemplary
sequence according to the present embodiment. FIG. 5 illustrates
gas supply timing based on the sequence of FIG. 4 according to the
present embodiment.
[0062] In the exemplary sequence according to the present
embodiment, a metal carbonitride film (a TiCN film) is formed on
the wafer 200 to a predetermined thickness by alternately
performing (a) the formation of a metal carbide layer (a TiC layer)
as a first layer containing titanium and carbon on the wafer 200 by
supplying a titanium (Ti)-containing gas and a carbon
(C)-containing gas onto the wafer 200 M times; and (b) the
formation of a metal carbonitride layer (a TiCN layer) as a second
layer containing titanium, carbon and nitrogen by supplying a
nitrogen (N)-containing gas onto the wafer 200 N times to nitride
the metal carbide layer (the TiC layer). The number of times the
nitrogen (N)-containing gas is supplied onto the wafer 200 in the
forming of the metal carbonitride layer (the TiCN layer), i.e., N
times, and the number of times the titanium (Ti)-containing gas and
the carbon (C)-containing gas are supplied onto the wafer 200 in
the forming of the metal carbide layer (the TiC layer), i.e., M
times, are determined (adjusted, tuned, or modulated) such that the
metal carbonitride film (the TiCN film) has a desired work
function. Here, "M" and "N" each denote a natural number.
[0063] When the term `wafer` is used in the present disclosure, it
should be understood as either the wafer itself, or both the wafer
and a stacked structure (assembly) including a layer/film formed on
the wafer (i.e., the wafer and the layer/film formed thereon may
also be collectively referred to as the `wafer`). Also, when the
expression `surface of the wafer` is used in the present
disclosure, it should be understood as either a surface (exposed
surface) of the wafer itself or a surface of a layer/film formed on
the wafer, i.e., an uppermost surface of the wafer as a stacked
structure.
[0064] Thus, in the present disclosure, the expression "specific
gas is supplied onto a wafer" should be understood to mean that the
specific gas is directly supplied onto a surface (exposed surface)
of the wafer or that the specific gas is supplied onto a surface of
a layer/film on the wafer, i.e., on the uppermost surface of the
wafer as a stacked structure. Also, in the present disclosure, the
expression `a layer (or film) is formed on the wafer` should be
understood to mean that the layer (or film) is directly formed on a
surface (exposed surface) of the wafer itself or that the layer (or
film) is formed on the layer/film on the wafer, i.e., on the
uppermost surface of the wafer as a stacked structure.
[0065] Also, in the present disclosure, the term `substrate` has
the same meaning as the term `wafer.` Thus, the term `wafer` may be
used interchangeably with the term `substate.`
[0066] The expression "supplying of a metal-containing gas and
carbon (C)-containing gas are performed M times" should be
understood to include, when the supplying of the metal-containing
gas and the supplying of the carbon-containing gas are set to one
set, performing the set once (i.e., M=1) or performing the set a
plurality of times (i.e., M=2 or more). That is, this expression
means that the set is performed once or more. The set is preferably
performed a plurality of times to obtain a TiCN film having a
relatively high concentration of carbon (C). The greater the number
of times the set is performed, the higher the concentration of
carbon (C) in the TiCN film. The set is preferably performed a
small number of times, e.g., only once, to obtain a TiCN film
having a relatively low concentration of carbon (C).
[0067] The expression "alternately performing the formation of a
TiC layer and the formation of a TiCN layer" should be understood
to include, when "a process of forming a TiC layer containing Ti
and C on the wafer 200 by supplying a Ti-containing gas and a
C-containing gas onto the wafer 200 in the process chamber 201 M
times" and "a process of forming a TiCN layer containing Ti, C and
N by supplying a N-containing gas onto the wafer 200 N times to
nitride the TiC layer" are set to one cycle, performing the cycle
once or performing the cycle a plurality of times. That is, this
expression means that the cycle is performed once or more (a
predetermined number of times). As will be described below, the
cycle is preferably performed a plurality of times.
[0068] Also, in the present disclosure, the term `metal film` means
a film formed of a conductive material including a metal atom, and
should be understood to include a conductive metal film formed of a
metal, a conductive metal nitride film, a conductive metal oxide
film, a conductive metal oxynitride film, a conductive metal
composite film, a conductive metal alloy film, a conductive metal
silicide film, a conductive metal carbide film, a conductive metal
carbonitride film, etc. Also, a TiCN film (titanium carbonitride
film) is a conductive metal carbonitride film.
[0069] (Wafer Charging and Boat Loading)
[0070] When a plurality of wafers 200 are placed on the boat 217
(wafer charging), the boat 217 supporting the plurality of wafers
200 is lifted by the boat elevator 115 and loaded into the process
chamber 201 (boat loading), as illustrated in FIG. 1. In this
state, the lower end of the reaction tube 203 is air-tightly closed
by the seal cap 219 via the O-ring 220.
[0071] (Pressure & Temperature Control)
[0072] The inside of the process chamber 201 is vacuum-exhausted to
have a desired pressure (degree of vacuum) by the vacuum pump 246.
In this case, the pressure in the process chamber 201 is measured
by the pressure sensor 245, and the APC valve 243 is
feedback-controlled based on information regarding the measured
pressure (pressure control). The operation of the vacuum pump 246
is maintained at least until processing of the wafers 200 is
completed. Also, the inside of the process chamber 201 is heated to
a desired temperature by the heater 207. In this case, a current
supply supplied to the heater 207 is feedback-controlled based on
temperature information detected by the temperature sensor 263, so
that the inside of the process chamber 201 may have a desired
temperature distribution (temperature control). The heating of the
inside of the process chamber 201 by the heater 207 is continuously
performed at least until the processing of the wafers 200 is
completed. Then, rotation of the boat 217 and the wafers 200 begins
due to the boat rotating mechanism 267. Also, the rotation of the
boat 217 and the wafers 200 by the boat rotating mechanism 267 is
continuously performed at least until the processing of the wafers
200 is completed. Thereafter, six steps which will be described
below are sequentially performed.
[0073] <Step 11>
[0074] (TiCl.sub.4 Gas Supply Process)
[0075] TiCl.sub.4 gas is supplied into the gas supply pipe 310 by
opening the valve 314 of the gas supply pipe 310. The flow rate of
the TiCl.sub.4 gas flowing in the gas supply pipe 310 is adjusted
by the MFC 312. The flow rate-adjusted TiCl.sub.4 gas is supplied
into the process chamber 201 via the gas supply holes 410a of the
nozzle 410, and exhausted via the exhaust pipe 231. In this case,
the TiCl.sub.4 gas is supplied onto the wafer 200. That is, a
surface of the wafer 200 is exposed to the TiCl.sub.4 gas. At the
same time, the valve 514 is opened to supply an inert gas, such as
N.sub.2 gas, into the carrier gas supply pipe 510. The flow rate of
the N.sub.2 gas flowing in the carrier gas supply pipe 510 is
adjusted by the MFC 512. The flow rate-adjusted N.sub.2 gas is
supplied into the process chamber 201 together with the TiCl.sub.4
gas, and exhausted via the exhaust pipe 231. Also, in this case,
the valves 524 and 534 are opened to supply N.sub.2 gas into the
carrier gas supply pipe 520 and the carrier gas supply pipe 530 so
as to prevent the TiCl.sub.4 gas from flowing into the nozzles 420
and 430. The N.sub.2 gas is supplied into the process chamber 201
via the gas supply pipe 320, the gas supply pipe 330, the nozzle
420 and nozzle 430, and exhausted via the exhaust pipe 231.
[0076] In this case, the APC valve 243 is appropriately adjusted to
set the pressure in the process chamber 201 to be within, for
example, a range of 10 to 2,000 Pa. The supply flow rate of the
TiCl.sub.4 gas controlled by the MFC 512 is set to be within, for
example, a range of 10 to 2,000 sccm. The supply flow rates of the
N.sub.2 gas controlled by the MFCs 512, 522 and 532 are set to be
within, for example, a range of 100 to 10,000 sccm. A duration for
which the TiCl.sub.4 gas is supplied onto the wafer 200, i.e., a
gas supply time (irradiation time), is set to be within, for
example, a range of 0.1 to 120 seconds. In this case, the
temperature of the heater 207 is set such that the temperature of
the wafer 200 is within, for example, a range of 200 to 400.degree.
C. When the temperature of the wafer 200 is less than 200.degree.
C., a TiC layer formed by sequentially performing Steps 11 to 14 a
predetermined number of times and a TiCN layer formed and NH.sub.3
supplied in Step 15 do not react with each other, thereby
preventing a TiCN layer from being formed in Step 15. When the
temperature of the wafer 200 is greater than 400.degree. C., a
gas-phase reaction is dominant, and film thickness uniformity is
likely to be degraded and may thus be difficult to control. Thus,
the temperature of the wafer 200 is preferably set to be within a
range of 200.degree. C. to 400.degree. C. When the TiCl.sub.4 gas
is supplied, a titanium (Ti)-containing layer that contains
chlorine (Cl), i.e., a layer that contains Ti and Cl, is formed on
the wafer 200. The titanium (Ti)-containing layer that contains
chlorine (Cl) may be a chemical adsorption layer of TiCl.sub.4 and
an intermediate of TiCl.sub.4 obtained when TiCl.sub.4 is
decomposed, a titanium (Ti) layer containing Cl and obtained when
TiCl.sub.4 is pyrolyzed, i.e., a Ti-deposited layer, or both of
these layers.
[0077] <Step 12>
[0078] (Residual Gas Removing Process)
[0079] After the Ti-containing layer that contains Cl is formed,
the valve 314 of the gas supply pipe 310 is closed to stop the
supply of the TiCl.sub.4 gas. In this case, the inside of the
process chamber 201 is vacuum-exhausted by the vacuum pump 246 in a
state in which the APC valve 243 of the exhaust pipe 231 is open,
thereby eliminating the TiCl.sub.4 gas (that did react or that
contributed to the formation of the Ti-containing layer that
contains Cl) remaining in the process chamber 201 from the process
chamber 201. In this case, N.sub.2 gas is continuously supplied
into the process chamber 201 while the valves 514, 524 and 534 are
open. The N.sub.2 gas acts as a purge gas to increase the effect of
eliminating the TiCl.sub.4 gas (that did not react or that
contributed to the formation of the Ti-containing layer that
contains Cl) remaining in the process chamber 201 from the process
chamber 201.
[0080] In this case, the gas remaining in the process chamber 201
may not be completely eliminated and the inside of the process
chamber 201 may not be completely purged. When a small amount of
gas remains in the process chamber 201, step 13 to be performed
thereafter will not be badly influenced by the gas. In this case,
the flow rate of the N.sub.2 gas to be supplied into the process
chamber 201 does not need to be high. For example, the inside of
the process chamber 201 may be purged without causing step 13 to be
badly influenced by the gas by supplying an amount of a gas
corresponding to the capacity of the reaction tube 203 (the process
chamber 201). As described above, since the inside of the process
chamber 201 is not completely purged, a purge time may be reduced
to improve the throughput. Furthermore, the consumption of the
N.sub.2 gas may be suppressed to a necessary minimum level.
[0081] <Step 13>
[0082] (Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 Gas
Supply Process)
[0083] After Step 12 is completed and a residual gas is removed
from the inside of the process chamber 201, the valve 324 of the
gas supply pipe 320 is opened to supply
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas into the gas
supply pipe 320. The flow rate of the
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas flowing in
the gas supply pipe 320 is adjusted by the MFC 322. The flow
rate-adjusted Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2
gas is supplied into the process chamber 201 via the gas supply
hole 420a of the nozzle 420, and exhausted via the exhaust pipe
231. In this case, the
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas is supplied
onto the wafer 200. That is, a surface of the wafer 200 is exposed
to the Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas. At
the same time, the valve 524 is opened to supply N.sub.2 gas into
the carrier gas supply pipe 520. The flow rate of the N.sub.2 gas
flowing in the carrier gas supply pipe 520 is adjusted by the MFC
522. The flow rate-adjusted N.sub.2 gas is supplied into the
process chamber 201, together with the
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas, and
exhausted via the exhaust pipe 231. In this case, the valves 514
and 534 are opened to supply N.sub.2 gas into the carrier gas
supply pipe 510 and the carrier gas supply pipe 530 so as to
prevent the Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas
from flowing into the nozzles 410 and 430. The N.sub.2 gas is
supplied into the process chamber 201 via the gas supply pipe 310,
the gas supply pipe 330 and the nozzles 410 and 430, and exhausted
via the exhaust pipe 231.
[0084] In this case, the APC valve 243 is appropriately adjusted to
set the pressure in the process chamber 201 to be within, for
example, a range of 10 to 2,000 Pa, similar to Step 11. The supply
flow rate of the Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2
gas adjusted by the MFC 322 is set to be within, for example, a
range of 10 sccm to 2,000 sccm. The supply flow rate of the N.sub.2
gas adjusted by the MFC 522 is set to be within, for example, a
range of 100 sccm to 10,000 sccm. A duration for which the
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas is supplied
onto the wafer 200, i.e., a gas supply time (irradiation time), is
set to be within, for example, a range of 0.1 to 120 seconds. In
this case, the temperature of the heater 207 is set such that the
temperature of the wafer 200 is within, for example, a range of 250
to 400.degree. C., similar to Step 11.
[0085] When the Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2
gas is supplied, the Ti-containing layer containing Cl formed on
the wafer 200 reacts with the
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas in Step 11.
In this case, mainly in Step 11, Cl contained in the Ti-containing
layer containing Cl formed on the wafer 200 reacts with
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2 of the
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas to form a
gas-phase material, and the gas-phase material is then discharged
as a gas. In this case, Cl contained in the Ti-containing layer
that contains Cl may react with a methyl group (CH.sub.3) or a
cyclopenta group (C.sub.5H.sub.4) in the
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas. In this
case, as Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 is
decomposed, hafnium (Hf), hydrogen (H), etc. contained in
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 may react with
Cl contained in the Ti-containing layer that contains Cl to form a
gas-phase material and the gas-phase material may be then
discharged as a gas. As described above, in Step 13, Cl contained
in TiCl.sub.4 and Hf contained in
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 are converted
into a gas-phase material and then the gas-phase material is
discharged. That is, Cl contained in TiCl.sub.4 and Hf contained in
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 are converted
into a gas-phase material containing Cl and a gas-phase material
containing Hf and/or a gas-phase material containing Cl and Hf, and
then the gas-phase materials or the gas-phase material is
discharged. Thus, Hf does not actually remain in a film to be
formed. Also, an effect of eliminating Cl from a film to be formed
may increase according to a synergistic effect. During this
process, C separated from a bond between C and H or a part of a
separated methyl group (CH.sub.3) as the
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas is
decomposed is not discharged as a gas, and remains and is bonded
with Ti contained in the Ti-containing layer that contains Cl.
Thus, the Ti-containing layer that contains Cl is modified into a
titanium carbide layer (TiC layer) that contains titanium (Ti) and
carbon (C).
[0086] <Step 14>
[0087] (Residual Gas Removing Process)
[0088] Thereafter, the valve 324 of the gas supply pipe 320 is
closed to stop the supply of the
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas. In this
case, the inside of the process chamber 201 is vacuum-exhausted by
the vacuum pump 246 in a state in which the APC valve 243 of the
exhaust pipe 231 is open, thereby eliminating the
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas (that did
react or that contributed to the formation of the TiC layer) or
byproducts remaining in the process chamber 201 from the process
chamber 201. In this case, N.sub.2 gas is continuously supplied
into the process chamber 201 while the valves 510, 520 and 530 are
open. The N.sub.2 gas acts as a purge gas to increase the effect of
eliminating the Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2
gas (that did not react or that contributed to the formation of the
TiC layer) or byproducts remaining in the process chamber 201 from
the process chamber 201.
[0089] In this case, the gas remaining in the process chamber 201
may not be completely eliminated and the inside of the process
chamber 201 may not be completely purged. When a small amount of
gas remains in the process chamber 201, step 11 or 15 to be
performed thereafter will not be badly influenced by the gas. In
this case, the flow rate of the N.sub.2 gas to be supplied into the
process chamber 201 does not need to be high. For example, the
inside of the process chamber 201 may be purged without causing
step 11 or 15 to be badly influenced by the gas by supplying an
amount of a gas corresponding to the capacity of the reaction tube
203 (the process chamber 201). As described above, since the inside
of the process chamber 201 is not completely purged, a purge time
may be reduced to improve the throughput. Furthermore, the
consumption of the N.sub.2 gas may be suppressed to a necessary
minimum level.
[0090] Then, Steps 11 to 14 described above are set to one set, and
the set is performed a predetermined number of times (M times) to
form a TiC layer to a predetermined thickness. FIG. 5 illustrates a
case in which the set is performed m times. The number of times the
set is performed, i.e., m times, may be set to be in a range of 1
to 200, preferably, a range of 1 to 100, and more preferably, a
range of 1 to 20. The number of times, i.e., m times, that the set
is performed may be, for example, a plurality of times, i.e., two
times to six times. By controlling (adjusting) the number of times
(m times) that the set is performed, the concentration of C in a
TiCN film to be finally formed may be controlled. A work function
of the TiCN film may be adjusted (tuned) to a desired level
according to a purpose by changing the concentration of C. To
obtain a TiCN film having a relatively high concentration of C, the
set is preferably performed a plurality of times. The concentration
of C in the TiCN film may be increased by increasing the number of
times a set is performed. To obtain a TiCN film having a relatively
low concentration of C, the number of times (m times) that the set
is performed is preferably set to a small number of times (e.g.,
once).
[0091] <Step 15>
[0092] (NH.sub.3 Gas Supply Process)
[0093] After the TiC layer is formed to the predetermined thickness
and a residual gas is removed from the inside of the process
chamber 201, the valve 334 of the gas supply pipe 330 is opened to
supply NH.sub.3 gas into the gas supply pipe 330. The flow rate of
the NH.sub.3 gas flowing in the gas supply pipe 330 is adjusted by
the MFC 322. The flow rate-adjusted NH.sub.3 gas is supplied into
the process chamber 201 via the gas supply holes 430a of the nozzle
430. The NH.sub.3 gas supplied into the process chamber 201 is
activated by heat and exhausted via the exhaust pipe 231. In this
case, the thermally activated NH.sub.3 gas is supplied onto the
wafer 200. That is, a surface of the wafer 200 is exposed to the
thermally activated NH.sub.3 gas. At the same time, the valve 534
is opened to supply N.sub.2 gas into the carrier gas supply pipe
530. The flow rate of the N.sub.2 gas flowing in the carrier gas
supply pipe 530 is adjusted by the MFC 532. The N.sub.2 gas is
supplied into the process chamber 201, together with the NH.sub.3
gas, and exhausted via the exhaust pipe 231. In this case, the
valves 514 and 524 are opened to supply N.sub.2 gas into the
carrier gas supply pipes 510 and 520 so as to prevent the NH.sub.3
gas from flowing into the nozzles 410 and 420. The N.sub.2 gas is
supplied into the process chamber 201 via the gas supply pipes 310
and 320 and the nozzles 410 and 420, and exhausted via the exhaust
pipe 231.
[0094] When the NH.sub.3 gas is activated by heat and supplied, the
APC valve 243 is appropriately controlled such that the pressure in
the process chamber 201 is in, for example, a range of 10 Pa to
2,000 Pa. By setting the pressure in the process chamber 201 to a
relatively high level as described above, the NH.sub.3 gas may be
thermally activated in a non-plasma state. When the NH.sub.3 gas is
activated by heat and supplied, a soft reaction may occur to softly
perform a nitriding action which will be described below. The
supply flow rate of the NH.sub.3 gas controlled by the MFC 332 is
set to be within, for example, a range of 10 sccm to 10,000 sccm.
The supply flow rates of the N.sub.2 gas controlled by the MFCs
512, 522 and 532 are set to be in, for example, a range of 100 sccm
to 10,000 sccm. A duration for which the NH.sub.3 gas activated by
heat is supplied onto the wafer 200, i.e., a gas supply time
(irradiation time), is set to range, for example, from 0.1 to 120
seconds. In this case, the temperature of the heater 207 is set
such that the temperature of the wafer 200 is within, for example,
a range of 200.degree. C. to 400.degree. C., similar to Steps 11
and 13.
[0095] In this case, the thermally activated NH.sub.3 gas is
supplied into the process chamber 201 by increasing the pressure in
the process chamber 201, and neither TiCl.sub.4 gas nor
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas is not
supplied into the process chamber 201. Thus, the NH.sub.3 gas does
not cause a gas-phase reaction, and the activated NH.sub.3 gas
reacts with at least a part of the TiC layer containing Ti and C
and formed on the wafer 200 in Step 13. Thus, the TiC layer is
nitrided and modified into a titanium carbonitride layer (a TiCN
layer). The TiCN layer may be also referred to as a C-doped TiN
layer (a C-added TiN layer).
[0096] When the TiC layer is thermally nitrided to be modified
(changed) into a TiCN layer by the thermally activated NH.sub.3
gas, the TiC layer is modified into a TiCN layer while adding
nitrogen (N) to the TiC layer. In this case, a number of Ti--N
bonds increase in the TiC layer due to an action of thermal
nitridation caused by the NH.sub.3 gas. That is, the TiC layer may
be modified into the TiCN layer while changing a composition ratio
of the TiC layer to increase the concentration of nitrogen therein.
Also, in this case, by controlling a process condition such as the
pressure in the process chamber 201 or a gas supply time, a ratio
of nitrogen (N) (i.e., the concentration of nitrogen (N)) in the
TiCN layer may be finely adjusted, thereby more finely controlling
a composition ratio of the TiCN layer.
[0097] <Step 16>
[0098] (Residual Gas Removing Process)
[0099] Then, the valve 334 of the gas supply pipe 330 is closed to
stop the supply of the NH.sub.3 gas. In this case, the inside of
the process chamber 201 is vacuum-exhausted by the vacuum pump 246
in a state in which the APC valve 243 of the exhaust pipe 231 is
open to eliminate the NH.sub.3 gas (that did react or that
contributed to the formation of the TiCN layer) or byproducts
remaining in the process chamber 201 from the process chamber 201.
In this case, N.sub.2 gas is continuously supplied into the process
chamber 201 while the valves 514, 524 and 534 are open. The N.sub.2
gas acts as a purge gas to increase the effect of eliminating the
NH.sub.3 gas (that did not react or that contributed to the
formation of the TiCN layer) or byproducts remaining in the process
chamber 201 from the process chamber 201.
[0100] In this case, the gas remaining in the process chamber 201
may not be completely eliminated and the inside of the process
chamber 201 may not be completely purged. When a small amount of
gas remains in the process chamber 201, Step 11 to be performed
thereafter will not be badly influenced by the gas. In this case,
the flow rate of the N.sub.2 gas to be supplied into the process
chamber 201 does not need to be high. For example, the inside of
the process chamber 201 may be purged without causing Step 11 to be
badly influenced by the gas by supplying an amount of a gas
corresponding to the capacity of the reaction tube 203 (the process
chamber 201). As described above, since the inside of the process
chamber 201 is not completely purged, a purge time may be reduced
to improve the throughput. Furthermore, the consumption of the
N.sub.2 gas may be suppressed to a necessary minimum level.
[0101] Thereafter, a cycle including a process of sequentially
performing Steps 11 to 14 a predetermined number of times and a
process of performing Steps 15 and 16 is performed a predetermined
number of times to form a TiCN film having a predetermined
composition ratio on the wafer 200 to a predetermined thickness.
The TiCN film may be also referred to as a C-doped TiN film
(C-added TiN film). FIG. 5 illustrates a case in which the cycle is
performed n times. By controlling (adjusting) the number of times
(n times) that the cycle is performed, a film thickness of a TiCN
film to be finally formed may be adjusted. For example, in order to
form a TiCN film for a gate electrode, which has a concentration of
C of 10 at % to 30 at % and a film thickness of 1 nm to 10 nm, the
n times the cycle is performed is set to be within a range of one
to five times. The cycle is preferably performed a plurality of
times. That is, a thickness of a TiCN layer to be formed per cycle
may be set to be less than a desired thickness and the cycle may be
performed a plurality of times until the TiCN layer may have the
desired thickness. As described above, when a thickness of the TiCN
layer to be formed per cycle is set to be less than the desired
thickness and the cycle is repeatedly performed a plurality of
times, an action of nitridation performed in Step 15 may be
delivered to the entire TiC layer. Also, the TiCN film may be more
uniformly nitrided to more uniformly control the concentration of N
in the TiCN film in a direction of the thickness thereof.
[0102] (Purging and Atmospheric Pressure Recovery)
[0103] After the TiCN film having the predetermined composition
ratio and film thickness is formed, an inert gas such as N.sub.2 is
supplied into the process chamber 201 and exhausted via the exhaust
pipe 231 to purge the inside of the process chamber 201 with the
inert gas (gas purging). Thereafter, an atmosphere in the process
chamber 201 is replaced with the inert gas (inert gas replacement),
and the pressure in the process chamber 201 is restored to normal
pressure (atmospheric pressure recovery).
[0104] (Boat Unloading and Wafer Discharging)
[0105] Then, the seal cap 219 is moved downward by the boat
elevator 115 to open the lower end of the reaction tube 203, and
the processed wafers 200 are unloaded to the outside of the
reaction tube 203 from the lower end of the reaction tube 203 while
being supported by the boat 217 (boat unloading). Thereafter, the
processed wafers 200 are unloaded from the boat 217 (wafer
discharging).
[0106] Although a case in which
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas is used as a
carbon source has been described above in the above embodiment, the
present invention is not limited thereto, and
Zr[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas, ethylene
(C.sub.2H.sub.4), propylene (C.sub.3H.sub.6), butene
(C.sub.4H.sub.8), pentene (C.sub.5H.sub.10), hexene
(C.sub.6H.sub.12), heptene (C.sub.7H.sub.14), octene
(C.sub.8H.sub.16), ethane (C.sub.2H.sub.6), propane
(C.sub.3H.sub.8), butane (C.sub.4H.sub.10), pentane
(C.sub.5H.sub.12), hexane (C.sub.6H.sub.14), heptane
(C.sub.7H.sub.16), octane (C.sub.8H.sub.18), etc. may be used as a
carbon source.
Second Embodiment
[0107] Next, a second embodiment of the present invention will be
described. In the first embodiment, a case in which a TiCN film is
formed on the wafer 200 to a predetermined thickness has been
described above. Similarly, in the second embodiment, a titanium
aluminum carbide film (TiAlC film) may be formed on the wafer 200
to a predetermined thickness, for example, by supplying three types
of gases. Here, the differences between the first embodiment and
the second embodiment will be described in detail, and a
description of parts of the second embodiment that are the same as
those of the first embodiment will be appropriately omitted.
[0108] FIG. 6 illustrates gas supply timing in a favorable sequence
of forming a TiAlC film by supplying three types of gases onto the
wafer 200. In the gas supply timing of FIG. 6, one set including a
process of alternately supplying titanium tetrachloride
(TiCl.sub.4) gas (which is a titanium (Ti)-containing gas) and
carbon (C)-containing gas onto the wafer 200 is repeatedly
performed, and a number of times (m times) that the set is
performed is controlled to control the concentration of C in a
TiAlC film to be finally formed, thereby adjusting (tuning) a work
function of the TiAlC film.
[0109] More specifically, a TiAlC film may be formed to a
predetermined thickness according to a sequence of (a) forming a
titanium carbide layer (TiC layer) containing titanium (Ti) and
carbon (C) on the wafer 200 by alternately supplying titanium
tetrachloride (TiCl.sub.4) gas which is a titanium (Ti)-containing
gas and carbon (C)-containing gas onto the wafer 200 in the process
chamber 201 M times; and (b) forming a titanium aluminum carbide
layer (TiAlC layer) containing titanium (Ti), carbon (C) and
aluminum (Al) by supplying trimethylaluminum [TMA,
(CH.sub.3).sub.3Al] as an Al-containing gas which is a metal source
gas containing aluminum (Al) on the wafer 200 in the process
chamber 201 N times. A titanium aluminum carbide film (TiAlC film)
is formed on the wafer 200 to a predetermined thickness by
alternately performing L times (a) the formation of a titanium
carbide layer (TiC layer) and (b) the formation of a titanium
aluminum carbide layer (TiAlC layer). The M times in (a) and the N
times in (b) are determined (adjusted, tuned, or modulated) such
that the TiAlC film has a desired work function (M, N, and L each
denote a natural number).
Third Embodiment
[0110] Next, a third embodiment of the present invention will be
described. Although a case in which three types of gases are used
to form a TiAlC film has been described above in the second
embodiment, the present invention is not limited thereto and a
TiAlC film may be formed using two types of process gases. FIG. 7
illustrates gas supply timing in a favorable sequence of forming a
TiAlC film by supplying two types of gases onto the wafer 200.
Here, the differences between the third embodiment and the first
and second embodiments and the second embodiment will be described
in detail, and a description of parts of the third embodiment that
are the same as those of the first and second embodiments will be
appropriately omitted.
[0111] In the gas supply timing of FIG. 7, a TiAlC film may be
formed on the wafer 200 to a predetermined thickness according to
the following sequence. A TiAlC layer containing Ti, Al and C is
formed on the wafer 200 by alternately performing (a) the supply of
TiCl.sub.4 gas as a Ti-containing gas on the wafer 200 in the
process chamber 201 M times; and (b) the supply of TMA gas as a
source containing C and Al N times. In this case, a work function
of the TiAlC film is adjusted (tuned) based on the ratio between
the M times in (a) and the N times in (b).
[0112] In this case, the greater the N times in (b), the higher the
concentration of C in the TiAlC film. As the concentration of C
increases, the work function of the TiAlC film decreases. Also, the
less the N times in (b) (e.g., the N times may be one), the lower
the concentration of C in TiAlC film. As the concentration of C
decreases, the work function of the TiAlC film increases.
[0113] Although a case in which TMA gas which is an Al-containing
gas is used as a metal source gas has been described above in the
previous embodiment of forming a TiAlC film, the present invention
is not limited thereto and AlCl.sub.3 or the like may be used.
[0114] Also, although cases in which a TiCN film or a TiAlC film
have been described above in the previous embodiments, the present
invention is not limited thereto and is preferably applicable to
forming a metal carbide film containing at least one metal element
selected from the group consisting of tantalum (Ta), cobalt (Co),
tungsten (W), molybdenum (Mo), ruthenium (Ru), yttrium (Y),
lanthanum (La), zirconium (Zr), and hafnium (Hf) or also forming a
silicide film containing the at least one metal element and silicon
(Si). In this case, tantalum tetrachloride (TaCl.sub.4), etc. may
be used as a Ta-containing source. Co and [(tBu)NC(CH.sub.3)
N(tBu).sub.2Co], etc. may be used as a Co-containing source.
Tungsten hexafluoride (WF.sub.6), etc. may be used as a
W-containing source. Molybdenum chloride (MoCl.sub.3 or
MoCl.sub.5), etc. may be used as a Mo-containing source.
2,4-dimethylpentadienyl(ethylcyclopentadienyl)ruthenium
[Ru(EtCp)(C.sub.7H.sub.11)], etc. may be used as a Ru-containing
source. Tris(ethylcyclopentadienyl)yttrium
[Y(C.sub.2H.sub.5C.sub.5H.sub.4).sub.3], etc. may be used as a
Y-containing source. Tris(isopropylcyclopentadienyl)lanthanum
[La(i-C.sub.3H.sub.7C.sub.5H.sub.4).sub.3], etc. may be used as a
La-containing source. Tetrakis(ethylmethylamino)zirconium
[Zr(N[CH.sub.3(C.sub.2H.sub.5)].sub.4)], etc. may be used as a
Zr-containing source. Tetrakis(ethylmethylamino)hafnium
[Hf(N[CH.sub.3(C.sub.2H.sub.5)].sub.4)], etc. may be used as an
Hf-containing source. Tetrachlorosilane (SiCl.sub.4),
hexachlorosilane (Si.sub.2Cl.sub.6), dichlorosilane
(SiH.sub.2Cl.sub.2), tris(dimethylamino)silane
(SiH[N(CH.sub.3).sub.2].sub.3, bis-tertiary-butyl aminosilane
(H.sub.2Si[HNC(CH.sub.3).sub.2].sub.2, etc. may be used as a
Si-containing source.
[0115] Next, a fourth embodiment of the present invention will be
described. Although a case in which a TiCN film is formed on the
wafer 200 to a predetermined thickness has been described above in
the first embodiment, a titanium aluminum carbonitride film (TiAlCN
film) may be formed on the wafer 200 to a predetermined film
thickness, for example, by supplying three types of gases in the
fourth embodiment. Here, the differences between the fourth
embodiment and the first embodiment and the second embodiment will
be described in detail, and a description of parts of the fourth
embodiment that are the same as those of the first embodiment will
be appropriately omitted.
[0116] Unlike the first embodiment, for example, TMA
[trimethylaluminum, (CH.sub.3 3)Al] containing at least elements of
carbon (C) and aluminum (Al) is supplied as a source gas containing
carbon and a second metal element into the process chamber 201
through the gas supply pipe 320 via the MFC 322, the valve 324 and
nozzle 420. When a liquid source, such as TMA, which is in a liquid
state at normal temperature and pressure, is used, the liquid
source is vaporized using a vaporization system such as a vaporizer
or a bubbler and supplied as a C-and-Al-containing gas. A
carbon-containing source supply system (or
carbon-and-metal-containing source supply system) is configured
with the second gas supply system.
[0117] Next, an example of the structure of a semiconductor device
according to the present embodiment will be described. Here, MOSFET
will be exemplified as a semiconductor device.
[0118] FIG. 8 illustrates the structure of a gate of a MOSFET. As
illustrated in FIG. 8, the gate of the MOSFET has a stack structure
in which a silicon-based insulating film formed of silicon oxide
(SiO.sub.2) and formed on a silicon (Si) substrate, a high-k film
formed of hafnium oxide (HfO.sub.2) and formed on the silicon oxide
(SiO.sub.2), and a titanium aluminum carbonitride (TiAlCN) film
formed on the hafnium oxide (HfO.sub.2) are stacked as metal films
for a gate electrode. The present embodiment is characterized in
forming the metal films that constitute the gate electrode.
[0119] <Process of Manufacturing Gate of Semiconductor
Device>
[0120] Next a process of manufacturing the gate of the MOSFET of
FIG. 8 will be described with reference to FIG. 9 below. FIG. 9 is
a flowchart of a process of manufacturing a gate of the
semiconductor device of FIG. 8 according to an embodiment of the
present invention.
[0121] First, a silicon (Si) substrate is processed with, for
example, a 1% HF aqueous solution to remove a sacrificial oxide
film of the Si-substrate (`HF treatment` process). Then, a silicon
oxide (SiO.sub.2) film is formed on a surface of the Si-substrate
through thermal oxidation (`SiO.sub.2 formation` process). The
SiO.sub.2 film is formed as an interface layer at the interface
between the Si-substrate and an HfO.sub.2 film which will be formed
later.
[0122] Next, a hafnium oxide (HfO.sub.2) film is formed as a high-k
film on the SiO.sub.2 film (`high-k formation` process). The
SiO.sub.2 film and the HfO.sub.2 film form a gate insulating film.
After the HfO.sub.2 film is formed, post-deposition annealing (PDA)
is performed ("post-deposition annealing" process). PDA is
performed by accommodating the Si-substrate on which the HfO.sub.2
film is formed in a process chamber of a thermal process furnace,
e.g., a rapid thermal process (RTP) device, and supplying N.sub.2
gas into the process chamber. PDA is performed to remove impurities
from the HfO.sub.2 film and to densify or crystallize the HfO.sub.2
film.
[0123] Next, a TiAlCN film is formed as a metal film on the
HfO.sub.2 film (`TiAlCN deposition` process). As illustrated in
FIG. 9, in a process of forming the TiAlCN film, a treatment of
forming a titanium nitride (TiN) layer (first layer) (`TiN
formation`) is performed X times (M times), and a treatment of
forming an AlCTiN layer (second layer) containing aluminum (Al),
carbon (C), titanium (Ti) and nitrogen (N) (`AlCTiN formation`) is
performed Y times (N times). Thereafter, a TiAlCN is formed by
alternately performing these treatments Z times (L times), as will
be described in detail below.
[0124] Then, a titanium nitride (TiN) film is formed as a cap film
on the TiAlCN film, for example, by physical vapor deposition (PVD)
(`cap TiN deposition` process). Then, a gate electrode is patterned
on the TiN film using a resist as a mask by photolithography (`gate
patterning` process), and is etched by dry etching (`gate etching`
process). Then, the resist is removed (`resist removal` process).
Then, forming gas annealing (FGA), such as hydrogen gas annealing,
is performed (forming gas annealing) (`FGA` process).
[0125] <Metal Film Forming Process>
[0126] Next, a process of forming metal films that constitute the
gate electrode described above will be described. The process of
forming metal films is performed, as a process included in a
process of manufacturing a semiconductor device (e.g., a MOSFET),
using the process furnace 202 of the substrate processing apparatus
10 described above.
[0127] A preferable sequence according to the present embodiment
includes a process of forming a metal film including nitrogen (N)
and carbon (C) in a predetermined ratio (e.g., a TiAlCN film) on
the wafer 200 by alternately performing L times the formation of a
first layer (e.g., a TiN layer) containing a metal element (e.g.,
Ti) and nitrogen (N) on the wafer 200 M times and the formation of
a second layer (e.g., an AlCTiN layer) containing the metal element
(e.g., Ti), nitrogen (N) and carbon (C) on the wafer 200 N times
(M, N, and L each denote a natural number).
[0128] Also, a preferable sequence according to the present
embodiment includes a process of forming a metal film (e.g., a
TiAlCN film) containing nitrogen (N) and carbon (C) in a
predetermined ratio on the wafer 200 by alternately performing L
times the alternately supplying of a first source (e.g.,
TiCl.sub.4) containing a metal element (e.g., Ti) and a second
source (e.g., NH.sub.3) containing nitrogen (N) onto the wafer 200
M times and the alternately supplying of a third source (e.g., TMA)
containing carbon (C), a fourth source (e.g., TiCl.sub.4)
containing the metal element (e.g., Ti), and a fifth source (e.g.,
NH.sub.3) containing nitrogen (N) onto the wafer 200 N times.
[0129] In the present embodiment, the M times, the N times and the
L times are determined by the ratio of nitrogen (N) or carbon (C)
in a metal film (e.g., the TiAlCN film) (in other words, a target
work function of the gate electrode). Also, the TiAlCN film
(titanium aluminum carbonitride film) is a conductive metal
carbonitride film.
[0130] FIG. 10 is a flowchart of a process of forming a metal film
(TiAlCN film), which is included in the flow of the process of
manufacturing a gate of FIG. 9. FIG. 11 illustrates gas supply
timing in the process of forming a metal film of FIG. 10. In the
following description, operations of various elements of the
substrate processing apparatus 10 are controlled by the controller
121.
[0131] (Wafer Charging and Boat Loading)
[0132] When a plurality of wafers 200 are placed on the boat 217
(wafer charging), the boat 217 supporting the plurality of wafers
200 is lifted by the boat elevator 115 and loaded into the process
chamber 201 (boat loading), as illustrated in FIG. 1. In this
state, the lower end of the reaction tube 203 is air-tightly closed
by the seal cap 219 via the O-ring 220.
[0133] (Pressure & Temperature Control)
[0134] The inside of the process chamber 201 is vacuum-exhausted to
have a desired pressure (degree of vacuum) by the vacuum pump 246.
In this case, the pressure in the process chamber 201 is measured
by the pressure sensor 245, and the APC valve 243 is
feedback-controlled based on information regarding the measured
pressure (pressure control). The operation of the vacuum pump 246
is maintained at least until processing of the wafers 200 is
completed. Also, the inside of the process chamber 201 is heated to
a desired temperature by the heater 207. In this case, a current
supply supplied to the heater 207 is feedback-controlled based on
temperature information detected by the temperature sensor 263, so
that the inside of the process chamber 201 may have a desired
temperature distribution (temperature control). The heating of the
inside of the process chamber 201 by the heater 207 is continuously
performed at least until the processing of the wafers 200 is
completed. Then, rotation of the boat 217 and the wafers 200 begins
due to the boat rotating mechanism 267. The rotation of the boat
217 and the wafers 200 by the boat rotating mechanism 267 is
continuously performed at least until the processing of the wafers
200 is completed.
[0135] Next, a process of forming a TiN layer (Steps 21 to 24) is
performed.
[0136] <Step 21>
[0137] (TiCl.sub.4 Gas Supply Process)
[0138] The valve 314 of the gas supply pipe 310 is opened to supply
TiCl.sub.4 gas as a first source into the gas supply pipe 310. The
flow rate of the TiCl.sub.4 gas flowing in the gas supply pipe 310
is adjusted by the MFC 312. The flow rate-adjusted TiCl.sub.4 gas
is supplied into the process chamber 201 via the gas supply holes
410a of the nozzle 410, and exhausted via the exhaust pipe 231. In
this case, the TiCl.sub.4 gas is supplied onto the wafer 200. That
is, a surface of the wafer 200 is exposed to the TiCl.sub.4 gas. At
the same time, the valve 514 is opened to supply an inert gas such
as N.sub.2 gas into the carrier gas supply pipe 510. The flow rate
of the N.sub.2 gas flowing in the carrier gas supply pipe 510 is
adjusted by the MFC 512. The flow rate-adjusted N.sub.2 gas is
supplied into the process chamber 201 together with the TiCl.sub.4
gas, and exhausted via the exhaust pipe 231. In this case, the
valves 524 and 534 are opened to supply N.sub.2 gas into the
carrier gas supply pipe 520, carrier gas supply pipe 530 so as to
prevent the TiCl.sub.4 gas from flowing into the nozzles 420 and
430. The N.sub.2 gas is supplied into the process chamber 201 via
the gas supply pipe 320, the gas supply pipe 330 and the nozzles
420 and 430, and exhausted via the exhaust pipe 231.
[0139] In this case, the APC valve 243 is appropriately adjusted to
set the pressure in the process chamber 201 to be within, for
example, a range of 1 to 10,000 Pa. The supply flow rate of the
TiCl.sub.4 gas controlled by the MFC 312 is set to be within, for
example, a range of 10 to 10,000 sccm. The supply flow rates of the
N.sub.2 gas controlled by the MFCs 512, 522 and 532 are set to be
within, for example, a range of 10 to 10,000 sccm. A duration for
which the TiCl.sub.4 gas is supplied onto the wafer 200, i.e., a
gas supply time (irradiation time), is set to be within, for
example, a range of 0.1 to 120 seconds. In this case, the
temperature of the heater 207 is set such that the temperature of
the wafer 200 is within, for example, a range of 200 to 500.degree.
C. When the TiCl.sub.4 gas is supplied, a Ti-containing layer is
formed on the wafer 200 to, for example, a thickness of less than
one atomic layer to several atomic layers.
[0140] <Step 22>
[0141] (Residual Gas Removing Process)
[0142] After the Ti-containing layer is formed, the valve 314 of
the gas supply pipe 310 is closed to stop the supply of the
TiCl.sub.4 gas. In this case, the inside of the process chamber 201
is vacuum-exhausted by the vacuum pump 246 in a state in which the
APC valve 243 of the exhaust pipe 231 is open, thereby eliminating
the TiCl.sub.4 gas (that did react or that contributed to the
formation of the Ti-containing layer that contains Cl) remaining in
the process chamber 201 from the process chamber 201. In this case,
N.sub.2 gas is continuously supplied into the process chamber 201
while the valves 514, 524 and 534 are open. The N.sub.2 gas acts as
a purge gas to increase the effect of eliminating the TiCl.sub.4
gas (that did not react or that contributed to the formation of the
Ti-containing layer that contains Cl) remaining in the process
chamber 201 from the process chamber 201.
[0143] In this case, the gas remaining in the process chamber 201
may not be completely eliminated and the inside of the process
chamber 201 may not be completely purged. When a small amount of
gas remains in the process chamber 201, a subsequent step to be
performed thereafter will not be badly influenced by the gas. In
this case, the flow rate of the N.sub.2 gas to be supplied into the
process chamber 201 does not need to be high. For example, the
inside of the process chamber 201 may be purged without causing the
subsequent step to be badly influenced by the gas by supplying an
amount of a gas corresponding to the capacity of the reaction tube
203 (the process chamber 201). As described above, since the inside
of the process chamber 201 is not completely purged, a purge time
may be reduced to improve the throughput. Furthermore, the
consumption of the N.sub.2 gas may be suppressed to a necessary
minimum level.
[0144] <Step 23>
[0145] (NH.sub.3 Gas Supply Process)
[0146] After the residual gas is removed from the inside of the
process chamber 201, the valve 334 of the gas supply pipe 330 is
opened to supply NH.sub.3 gas into the gas supply pipe 330. The
flow rate of the NH.sub.3 gas flowing in the gas supply pipe 330 is
adjusted by the MFC 332. The flow rate-adjusted NH.sub.3 gas is
supplied into the process chamber 201 via the gas supply holes 430a
of the nozzle 430. The NH.sub.3 gas supplied into the process
chamber 201 is activated by heat, and exhausted via the exhaust
pipe 231. In this case, the thermally activated NH.sub.3 gas is
supplied onto the wafer 200. That is, a surface of the wafer 200 is
exposed to the thermally activated NH.sub.3 gas. At the same time,
the valve 534 is opened to supply N.sub.2 gas into the carrier gas
supply pipe 530. The flow rate of the N.sub.2 gas flowing in the
carrier gas supply pipe 530 is adjusted by the MFC 532. The N.sub.2
gas is supplied into the process chamber 201, together with the
NH.sub.3 gas, and exhausted via the exhaust pipe 231. In this case,
the valves 514 and 524 are opened to supply N.sub.2 gas into the
carrier gas supply pipes 510 and 520 so as to prevent the NH.sub.3
gas from flowing into the nozzles 410 and 420. The N.sub.2 gas is
supplied into the process chamber 201 via the gas supply pipes 310
and 320 and the nozzles 410 and 420, and exhausted via the exhaust
pipe 231.
[0147] When the NH.sub.3 gas is activated by heat and supplied, the
APC valve 243 is appropriately controlled such that the pressure in
the process chamber 201 is in, for example, a range of 1 Pa to
10,000 Pa. The supply flow rate of the NH.sub.3 gas controlled by
the MFC 332 is set to be within, for example, a range of 10 sccm to
50,000 sccm. The supply flow rates of the N.sub.2 gas controlled by
the MFCs 512, 522 and 532 are set to be in, for example, a range of
10 sccm to 10,000 sccm. A duration for which the NH.sub.3 gas
activated by heat is supplied onto the wafer 200, i.e., a gas
supply time (irradiation time), is set to range, for example, from
0.1 to 120 seconds. In this case, the temperature of the heater 207
is set such that the temperature of the wafer 200 is within, for
example, a range of 200.degree. C. to 500.degree. C., similar to
Step 21.
[0148] In this case, the thermally activated NH.sub.3 gas is
supplied into the process chamber 201 by increasing pressure in the
process chamber 201. The activated NH.sub.3 gas reacts with at
least a portion of the Ti-containing layer formed on the wafer 200
in Step 21. Accordingly, the Ti-containing layer is nitrided to be
modified into a titanium nitride layer (a TiN layer).
[0149] <Step 24>
[0150] (Residual Gas Removing Process)
[0151] After the TiN layer is formed, the valve 334 of the gas
supply pipe 330 is closed to stop the supply of the NH.sub.3 gas.
In this case, the inside of the process chamber 201 is
vacuum-exhausted by the vacuum pump 246 in a state in which the APC
valve 243 of the exhaust pipe 231 is open, thereby eliminating the
NH.sub.3 gas (that did react or that contributed to the formation
of the TiN layer) or byproducts remaining in the process chamber
201 from the process chamber 201. In this case, N.sub.2 gas is
continuously supplied into the process chamber 201 while the valves
514, 524 and 534 are open. The N.sub.2 gas acts as a purge gas to
increase the effect of eliminating the NH.sub.3 gas (that did not
react or that contributed to the formation of the TiN layer) or
byproducts remaining in the process chamber 201 from the process
chamber 201.
[0152] In this case, the gas remaining in the process chamber 201
may not be completely eliminated and the inside of the process
chamber 201 may not be completely purged. When a small amount of
gas remains in the process chamber 201, a subsequent step to be
performed thereafter will not be badly influenced by the gas. In
this case, the flow rate of the N.sub.2 gas to be supplied into the
process chamber 201 does not need to be high. For example, the
inside of the process chamber 201 may be purged without causing the
subsequent step to be badly influenced by the gas by supplying an
amount of a gas corresponding to the capacity of the reaction tube
203 (the process chamber 201). As described above, since the inside
of the process chamber 201 is not completely purged, a purge time
may be reduced to improve the throughput. Furthermore, the
consumption of the N.sub.2 gas may be suppressed to a necessary
minimum level.
[0153] Steps 21 to 24 described above are performed only
predetermined X times (M times). That is, one set including Steps
21 to 24 is performed only X times. As described above, the
supplying of the TiCl.sub.4 gas and the supplying of the NH.sub.3
gas are alternately performed X times to form a TiN layer (first
layer) to a predetermined thickness, for example, a thickness of
0.03 nm to 20 nm.
[0154] After Steps 21 to 24 described above are performed X times
(X sets), a process of forming an AlCTiN layer (Steps 25 to 30)
which will be described below is performed.
[0155] <Step 25>
[0156] (TMA Gas Supply Process)
[0157] The valve 324 of the gas supply pipe 320 is opened to supply
TMA [trimethylaluminum (CH.sub.3).sub.3A1] gas into the gas supply
pipe 320. The flow rate of the TMA gas flowing in the gas supply
pipe 320 is adjusted by the MFC 322. The flow rate-adjusted TMA gas
is supplied into the process chamber 201 via the gas supply holes
420a of the nozzle 420, and exhausted via the exhaust pipe 231. In
this case, the TMA gas is supplied onto the wafer 200. That is, a
surface of the wafer 200 is exposed to the TMA gas. At the same
time, the valve 524 is opened to supply N.sub.2 gas into the
carrier gas supply pipe 520. The flow rate of the N.sub.2 gas
flowing in the carrier gas supply pipe 520 is adjusted by the MFC
522. The flow rate-adjusted N.sub.2 gas is supplied into the
process chamber 201 together with the TMA gas, and exhausted via
the exhaust pipe 231. In this case, the valves 514 and 534 are
opened to supply N.sub.2 gas into the carrier gas supply pipes 510
and 530 so as to prevent the TMA gas from flowing into the nozzles
410 and 430. The N.sub.2 gas is supplied into the process chamber
201 via the gas supply pipe 310, the gas supply pipe 330 and the
nozzles 410 and 430, and exhausted via the exhaust pipe 231.
[0158] In this case, the APC valve 243 is appropriately adjusted to
set the pressure in the process chamber 201 to be within, for
example, a range of 1 to 10,000 Pa, similar to Step 21. The supply
flow rate of the TMA gas controlled by the MFC 332 is set to be
within, for example, a range of 10 to 10,000 sccm. The supply flow
rates of the N.sub.2 gas controlled by the MFCs 512, 522 and 532
are set to be within, for example, a range of 100 to 10,000 sccm. A
duration for which the TMA gas is supplied onto the wafer 200,
i.e., a gas supply time (irradiation time), is set to be within,
for example, a range of 0.1 to 120 seconds. In this case, the
temperature of the heater 207 is set such that the temperature of
the wafer 200 is within, for example, a range of 200 to 500.degree.
C., similar to Step 21. When the TMA gas is supplied, a layer that
contains carbon (C) and aluminum (Al) is formed on the TiN layer.
The layer that contains carbon (C) and aluminum (Al) has a
thickness, for example, of less than one atomic layer to several
atomic layers.
[0159] <Step 26>
[0160] (Residual Gas Removing Process)
[0161] Thereafter, the valve 324 of the gas supply pipe 320 is
closed to stop the supply of the TMA gas. In this case, the inside
of the process chamber 201 is vacuum-exhausted by the vacuum pump
246 in a state in which the APC valve 243 of the exhaust pipe 231
is open, thereby eliminating the TMA gas (that did react or that
contributed to the formation of the layer that contains C and Al)
remaining in the process chamber 201 from the process chamber 201.
In this case, N.sub.2 gas is continuously supplied into the process
chamber 201 while the valves 510, 520 and 530 are open. The N.sub.2
gas acts as a purge gas to increase the effect of eliminating the
TMA gas (that did not react or that contributed to the formation of
the Ti-containing layer that contains C and Al) remaining in the
process chamber 201 from the process chamber 201.
[0162] In this case, the gas remaining in the process chamber 201
may not be completely eliminated and the inside of the process
chamber 201 may not be completely purged. When a small amount of
gas remains in the process chamber 201, a subsequent step to be
performed thereafter will not be badly influenced by the gas. In
this case, the flow rate of the N.sub.2 gas to be supplied into the
process chamber 201 does not need to be high. For example, the
inside of the process chamber 201 may be purged without causing the
subsequent step to be badly influenced by the gas by supplying an
amount of a gas corresponding to the capacity of the reaction tube
203 (the process chamber 201). As described above, since the inside
of the process chamber 201 is not completely purged, a purge time
may be reduced to improve the throughput. Furthermore, the
consumption of the N.sub.2 gas may be suppressed to a necessary
minimum level.
[0163] <Step 27>
[0164] (TiCl.sub.4 Gas Supply Process)
[0165] Next, TiCl.sub.4 gas is supplied into the process chamber
201, similar to Step 21. In this case, the APC valve 243 is
appropriately adjusted to set the pressure in the process chamber
201 to be within, for example, a range of 1 to 10,000 Pa. The
supply flow rate of the TiCl.sub.4 gas controlled by the MFC 312 is
set to be within, for example, a range of 10 to 10,000 sccm. The
supply flow rates of the N.sub.2 gas controlled by the MFCs 512,
522 and 532 are set to be within, for example, a range of 10 to
10,000 sccm. A duration for which the TiCl.sub.4 gas is supplied
onto the wafer 200, i.e., a gas supply time (irradiation time), is
set to be within, for example, a range of 0.1 to 120 seconds. In
this case, the temperature of the heater 207 is set such that the
temperature of the wafer 200 is within, for example, a range of 200
to 500.degree. C. The TiCl.sub.4 gas supplied into the process
chamber 201 reacts with at least a part of the layer that contains
C and Al. Thus, the layer that contains C and Al is modified into a
layer that contains carbon (C), aluminum (Al) and titanium
(Ti).
[0166] <Step 28>
[0167] (Residual Gas Process)
[0168] Thereafter, the TiCl.sub.4 gas (that did not react or that
contributed to the formation of the layer that contains carbon (C),
aluminum (Al) and titanium (Ti)) or byproducts remaining in the
process chamber 201 are eliminated from the inside of the process
chamber 201, similar to Step 22.
[0169] <Step 29>
[0170] (NH.sub.3 Gas Supply Process)
[0171] Next, NH.sub.3 gas is supplied into the process chamber 201,
similar to Step 23. In this case, the APC valve 243 is
appropriately adjusted to set the pressure in the process chamber
201 to be within, for example, a range of 1 to 10,000 Pa. The
supply flow rate of the NH.sub.3 gas controlled by the MFC 322 is
set to be within, for example, a range of 10 to 50,000 sccm. The
supply flow rates of the N.sub.2 gas controlled by the MFCs 512,
522 and 532 are set to be within, for example, a range of 10 to
10,000 sccm. A duration for which the NH.sub.3 gas activated by
heat is supplied onto the wafer 200, i.e., a gas supply time
(irradiation time), is set to be within, for example, a range of
0.1 to 120 seconds. In this case, the temperature of the heater 207
is set such that the temperature of the wafer 200 is within, for
example, a range of 200 to 500.degree. C., similar to Step 21. The
NH.sub.3 gas supplied into the process chamber 201 reacts with at
least a part of the layer that contains C, Al and Ti. Thus, the
layer that contains C, Al and Ti is modified into the
AlCTiN-containing layer described above.
[0172] <Step 30>
[0173] (Residual Gas Removing Process)
[0174] Thereafter, the TiCl.sub.4 gas (that did not react or that
contributed to the formation of the AlCTiN-containing layer) or
byproducts remaining in the process chamber 201 are eliminated from
the inside of the process chamber 201, similar to Step 24.
[0175] Steps 25 to 30 described above are performed only
predetermined Y times (N times). That is, one set including Steps
25 to 30 is performed only Y times. As described above, the
supplying of the TMA gas, the supplying of the TiCl.sub.4 gas and
the supplying of the NH.sub.3 gas are alternately performed Y times
to form an AlCTiN layer (second layer) to a predetermined
thickness, for example, a thickness of 0.1 nm to 20 nm.
[0176] The TiAlCN film as a gate electrode has a stack structure
including the TiN layer and the AlCTiN layer described above. The
forming of the TiN layer and the forming of the AlCTiN layer are
alternately and repeatedly performed Z times (L times) to form the
TiAlCN film to a predetermined thickness (e.g., a thickness of 1.0
to 20 nm). The TiAlCN film may be also referred to as an AlC-doped
TiN film (AlC-added TiN film) obtained by doping Al and C onto the
TiN film.
[0177] Here, a ratio of each of the elements of TiAlCN film may be
adjusted, based on the number of times Steps 21 to 24 of forming
the TiN layer are performed (`X` or the product of `X` and `Z`
described above) and the number of times Steps 25 to 30 of forming
the AlCTiN layer are performed (`Y` or the product of `Y` and `Z`
described above). That is, by adjusting the number of times each of
the steps described above are performed, a work function of a gate
electrode formed of the TiAlCN film may be tuned (adjusted or
modulated). In other words, `X`, `Y`, and `Z` are determined based
on the ratio of nitrogen or carbon (or the ratios of nitrogen,
carbon, titanium and aluminum) contained in the TiAlCN film. Also,
`X` and `Y` each denote an integer that is equal to or greater than
`0`, and `Z` denotes an integer that is equal to or greater than
`1.` `X` and/or `Y` are preferably set to be each an integer that
is equal to or greater than `1.`
[0178] Both the work functions of two elements (Ti and Al) among
the elements contained in the TiAlCN film are about 4.3 eV. The
inventors of the present application have found that a work
function of a TiAlCN film may be increased or decreased by
adjusting the ratio of C or N, based on the work functions of Ti
and Al, i.e., about 4.3 eV. In detail, the work function is lower
than 4.3 eV when the ratio of C is increased, and is higher than
4.3 eV when the ratio of N is increased. Thus, a metal film having
a desired work function may be formed by determining `X`, `Y` and
`Z` based on the ratio of N or C contained in the TiAlCN film.
[0179] (Purging and Atmospheric Pressure Recovery)
[0180] After the TiAlCN film is formed to the predetermined
thickness, an inert gas such as N.sub.2 is supplied into the
process chamber 201 and exhausted via the exhaust pipe 231 to purge
the inside of the process chamber 201 with the inert gas (gas
purging). Thereafter, an atmosphere in the process chamber 201 is
replaced with the inert gas (inert gas replacement), and the
pressure in the process chamber 201 is restored to normal pressure
(atmospheric pressure recovery).
[0181] (Boat Unloading and Wafer Discharging)
[0182] Then, the seal cap 219 is moved downward by the boat
elevator 115 to open the lower end of the reaction tube 203, and
the processed wafers 200 are unloaded to the outside of the
reaction tube 203 from the lower end of the reaction tube 203 while
being supported by the boat 217 (boat unloading). Thereafter, the
processed wafers 200 are unloaded from the boat 217 (wafer
discharging).
Fifth Embodiment
[0183] Next, a fifth embodiment of the present invention will be
described below. The TiN layer, i.e., a metal nitride film, is
formed as the first layer of the TiAlCN film in the fourth
embodiment, whereas a metal carbide film is formed instead of a
metal nitride film in the fifth embodiment.
[0184] For example, a TiAlCN film that includes a metal carbide
film as a first layer may be formed in the following sequence. The
sequence includes a process of forming a metal film (e.g., a
TiAlCN) which includes nitrogen (N) and carbon (C) in a
predetermined ratio on the wafer 200 by alternately performing L
times the formation of a first layer (e.g., a TiC layer) containing
a metal element (e.g., Ti) and carbon (C) on the wafer 200 M times
and the formation of a second layer (e.g., AlCTiN) containing the
metal element (e.g., Ti), nitrogen (N) and carbon (C) on the wafer
200 N times.
[0185] Also, an exemplary sequence according to the present
embodiment includes a process of forming a metal film (e.g., a
TiAlCN film) containing nitrogen (N) and carbon (C) in a
predetermined ratio on the wafer 200 by alternately performing L
times the alternately supplying of a first source (e.g.,
TiCl.sub.4) containing a metal element (e.g., Ti) and a second
source (e.g., Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2)
containing carbon (C) onto the wafer 200 M times; and the
alternately supplying of a third source (e.g., TMA) containing
carbon (C), a fourth source (e.g., TiCl.sub.4) containing the metal
element (e.g., Ti) and a fifth source (e.g., NH.sub.3) containing
nitrogen (N) onto the wafer 200 N times. Also, in this sequence, a
gas supply system configured to supply
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 into the process
chamber 201 is further included in the substrate processing
apparatus 10.
[0186] Although cases in which a TiAlCN film is formed as a metal
film of a gate electrode have been described in the fourth and
fifth embodiments described above, the metal film is not limited
thereto, and the present invention is applicable to forming a metal
carbide film, a metal nitride film, or a metal carbonitride film
containing at least one metal element selected from the group
consisting of tantalum (Ta), cobalt (Co), tungsten (W), molybdenum
(Mo), ruthenium (Ru), yttrium (Y), lanthanum (La), zirconium (Zr),
and hafnium (Hf) or forming a silicide film containing the at least
one metal element and silicon (Si). In this case, tantalum
tetrachloride (TaCl.sub.4), etc. may be used as a Ta-containing
source. Co and [(tBu)NC(CH.sub.3)N(tBu).sub.2Co], etc. may be used
as a Co-containing source. Tungsten hexafluoride (WF.sub.6), etc.
may be used as a W-containing source. Molybdenum chloride
(MoCl.sub.3 or MoCl.sub.5), etc. may be used as a Mo-containing
source. 2,4-dimethylpentadienyl(ethylcyclopentadienyl)ruthenium
[Ru(EtCp)(C.sub.7H.sub.11)], etc. may be used as a Ru-containing
source. Tris(ethylcyclopentadienyl)yttrium
[Y(C.sub.2H.sub.5C.sub.5H.sub.4).sub.3], etc. may be used as a
Y-containing source. Tris(isopropylcyclopentadienyl)lanthanum
[La(i-C.sub.3H.sub.7C.sub.5H.sub.4).sub.3], etc. may be used as a
La-containing source. Tetrakis(ethylmethylamino)zirconium
[Zr(N[CH.sub.3(C.sub.2H.sub.5)].sub.4)], etc. may be used as a
Zr-containing source. Tetrakis(ethylmethylamino)hafnium
[Hf(N[CH.sub.3(C.sub.2H.sub.5)].sub.4)], etc. may be used as an
Hf-containing source. Tetrachlorosilane (SiCl.sub.4),
hexachlorosilane (Si.sub.2Cl.sub.6), dichlorosilane
(SiH.sub.2Cl.sub.2), tris(dimethylamino)silane
(SiH[N(CH.sub.3).sub.2].sub.3, bis-tertiary-butyl aminosilane
(H.sub.2Si[HNC(CH.sub.3).sub.2].sub.2, etc. may be used as a
Si-containing source.
[0187] Although cases in which TMA gas or
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas is used as a
carbon-containing source have been described above in the fourth
and fifth embodiments, the present invention is not limited
thereto, and Zr[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2
gas, ethylene (C.sub.2H.sub.4), propylene (C.sub.3H.sub.6), butene
(C.sub.4H.sub.8), pentene (C.sub.5H.sub.10), hexene
(C.sub.6H.sub.12), heptene (C.sub.7H.sub.14), octene
(C.sub.8H.sub.16), ethane (C.sub.2H.sub.6), propane
(C.sub.3H.sub.8), butane (C.sub.4H.sub.10), pentane
(C.sub.5H.sub.12), hexane (C.sub.6H.sub.14), heptane
(C.sub.7H.sub.16), octane (C.sub.8H.sub.18), etc. may be used as a
carbon source.
[0188] Also, although cases in which the first layer includes one
metal element have been described above in the fourth and fifth
embodiments, the present invention is not limited thereto and the
first layer may include two or more metal elements (e.g., Ti and
Al). Also, although the same metal element is included in the first
and second layers in the above fourth and fifth embodiments, the
present invention is not limited thereto. For example, the first
layer may include Ti and the second layer may not include Ti in the
above embodiments.
[0189] When the ratio of C contained in the metal film is `0` in
the above fourth and fifth embodiments, a TiAlN film or a TiN film
may be formed instead of the TiAlCN film. Also, when the ratio of N
contained in the metal film is `0`, a TiAlC film or a TiC film may
be formed instead of the TiAlCN film.
[0190] Also, although a TiN layer and an AlCTiN layer are
sequentially formed to form a TiAlCN film in the above fourth and
fifth embodiments, the AlCTiN layer and the TiN layer may be
sequentially formed. Similarly, the AlCTiN layer and the TiC layer
may be sequentially formed instead of in the order of the TiC layer
and the AlCTiN layer.
[0191] The above embodiments, modified examples, and application
examples may be used in appropriate combination. Also, the present
invention is not limited to the above embodiments and may be
embodied in many different forms without departing from the scope
of the invention.
[0192] In the previous embodiments, cases in which a film is formed
using a batch-type vertical substrate processing apparatus capable
of processing a plurality of substrates at one time have been
described above. However, the present invention is not limited
thereto and is preferably applicable to a case in which a film is
formed using a single-substrate processing apparatus capable of
processing one or several substrates at one time. Also, although
cases in which a film is formed using a substrate processing
apparatus including a hot wall type process furnace have been
described in the previous embodiments, the present invention is not
limited thereto and is preferably applicable to cases in which a
film is formed using a substrate processing apparatus including a
cold wall type process furnace
[0193] Also, although cases in which TiCl.sub.4 gas is used as a
metal source gas which is a Ti-containing source have been
described in the previous embodiments, the present invention is not
limited thereto, and not only a halide such as
tetrakis(dimethylamino)titanium (TDMAT,
Ti[N(CH.sub.3).sub.2].sub.4), tetrakis(diethylamino) titanium
(TDEAT, Ti[N(CH.sub.2CH.sub.3).sub.2].sub.4), etc. but also an
organic compound or a titanium (Ti)-containing gas which is an
amino-based compound may be used.
[0194] Also, in the previous embodiments, cases in which NH.sub.3
gas is used as a nitriding gas have been described, the present
invention is not limited thereto, and diazene (N.sub.2H.sub.2) gas,
hydrazine (N.sub.2H.sub.4) gas, N.sub.3H.sub.8 gas, nitrogen
(N.sub.2), nitrous oxide (N.sub.2O), monomethyl hydrazine
(CH.sub.6N.sub.2), dimethyl hydrazine (C.sub.2H.sub.8N.sub.2), etc.
may be used.
[0195] As an inert gas, not only N.sub.2 gas but also a rare gas,
such as Ar gas, He gas, Ne gas, Xe gas, etc., may be used.
[0196] Also, the present invention may be accomplished, for
example, by changing a process recipe installed in an existing
substrate processing apparatus. In order to change the installed
process recipe, a process recipe according to the present invention
may be installed in the existing substrate processing apparatus via
an electrical communication line or a recording medium storing the
process recipe according to the present invention. Otherwise, the
process recipe installed in the existing substrate processing
apparatus may be directly changed to the process recipe according
to the present invention by manipulating an I/O device of the
existing substrate processing apparatus.
[0197] Various examples of the present invention will be described
below but the present invention is not limited thereto.
Example 1
[0198] A TiCN film was formed on the wafer 200 according to the
sequence according to the above first embodiment, and an experiment
was conducted to perform an X-ray photoelectron spectroscopy (XPS)
analysis thereon. In Example 1, a TiCN film was formed according to
the film-forming flow of FIG. 4 and the gas supply timing of FIG. 5
by using TiCl.sub.4 gas which is a Ti-containing gas as a first
process gas, Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas
which is a C-containing gas as a second process gas, and NH.sub.3
gas which is an N-containing gas as a third process gas. That is,
the wafer 200 was loaded in the process chamber 201 (wafer
loading), the wafer 200 was heated in an N.sub.2 atmosphere
(preheating), a TiC layer (a metal carbide layer) was formed by
alternately and repeatedly supplying TiCl.sub.4 gas and
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas, NH.sub.3
was alternately and repeatedly supplied onto the TiC layer
(nitriding), a TiCN film was formed, residual gases are exhausted
from the process chamber 201 (gas exhausting), the wafer 200 on
which the TiCN film was formed was unloaded from the process
chamber 201 (wafer unloading), and the XPS analysis was conducted.
In this case, process conditions in each of the steps were set as
follows.
[0199] (Step 11)
[0200] Temperature in process chamber: 400.degree. C.;
[0201] Pressure in process chamber: 50 Pa (0.38 Torr);
[0202] Supply flow rate of TiCl.sub.4 gas: 10 sccm to 50 sccm;
and
[0203] Duration for which TiCl.sub.4 gas was irradiated: 2
seconds
[0204] (Step 13)
[0205] Temperature in process chamber: 400.degree. C.;
[0206] Pressure in process chamber: 50 Pa (0.38 Torr);
[0207] Supply flow rate of
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas: 10 sccm to
50 sccm; and
[0208] Duration for which
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas was
irradiated: 50 seconds
[0209] (Step 15)
[0210] Temperature in process chamber: 400.degree. C.;
[0211] Pressure in process chamber: 50 Pa (0.38 Torr);
[0212] Supply flow rate of NH.sub.3 gas: 1,000 sccm; and
[0213] Duration for which NH.sub.3 gas was irradiated: 20
seconds
[0214] In this case, when Steps 15 and 16 were performed once, a
number of times one set including Steps 11 to 14 was performed,
i.e., a number of sets a TiC layer was formed, was set to be one
(m=1). The TiCN film was formed to a thickness of 5 nm, and a 5 nm
TiN film was formed as a cap layer on the TiCN film in-situ.
Example 2
[0215] According to Example 2, a TiCN film was formed by setting a
number of times one set including Steps 11 to 14 was performed,
i.e., a number of sets a TiC layer formed, to three sets (m=3),
when Steps 15 and 16 were performed once. The other process
conditions were set to be the same as those of Example 1.
Example 3
[0216] According to Example 3, a TiCN film was formed by setting a
number of times one set including Steps 11 to 14 was performed,
i.e., a number of sets a TiC layer was formed, to five sets (m=5)
when Steps 15 and 16 were performed once. The other process
conditions were set to be the same as those of Example 1.
[0217] Table 1 shows the process conditions and the concentrations
of C in the TiCN films according to Examples 1 to 3. The
concentration of C in the TiCN film was 17% to 18% in Example 1,
was 25% to 30% in Example 2, and was 25% to 30% in Example 3.
TABLE-US-00001 TABLE 1 Metal gate Number of electrode Gapping layer
sets m C concentration Example 1 TiCN TiN 1 set.sup. 17%-18%
Example 2 (5 .mu.m) (5 .mu.m) 3 sets 25%-30% Example 3 5 sets
25%-30%
[0218] Next, the experimental results according to Examples 1 to 3
will be described below.
[0219] FIG. 12 is a graph illustrating a ratio of C/Ti which is the
ratio between the concentrations of C and Ti, measured by
conducting the XPS analysis on the TiCN films according to Examples
1 to 3. In FIG. 12, the horizontal axis denotes a number of steps m
Step 11 to 14 are performed, and the vertical axis denotes a ratio
of C/Ti, measured through the XPS analysis. Here, the ratio of C/Ti
may be understood to mean the concentration of carbon (C) in the
TiCN film. It is noted from the measurement result that the
concentration of C increased at least until m=3. That is, the
concentrations of carbon (C) in the TiCN films may be controlled by
controlling a number of sets Steps 11 to 14 are performed. Also,
the concentration of C when m=5 was substantially the same as when
m=3, and saturated.
[0220] FIG. 13A is a graph illustrating the concentration of carbon
(C) in the TiCN films according to Examples 1 to 3, measured by
XPS. FIG. 13B is a graph illustrating the concentration of nitrogen
(N) in the TiCN films according to Examples 1 to 3, measured by
XPS. In FIGS. 13A and 13B, the horizontal axes each denote an etch
time, and the vertical axes denote the concentration of atoms of C
(C at %) and the concentration of atoms of N (N at %),
respectively. Tops of FIGS. 13A and 13B indicate the layers each
etched at a corresponding etch time and illustrated along the
horizontal axis.
[0221] In FIG. 13A, the result of analyzing the TiCN films revealed
that the concentration of C increased by about 11% at the etch
times in Examples 2 and 3, compared to Example 1. In FIG. 13B, the
result of analyzing the TiCN films revealed that the concentration
of N decreased by about 3.6% at the etch times in Examples 2 and 3,
compared to Example 1. As described above, a comparison of FIGS.
13A and 13B reveals that there is a trade-off between the
concentration of atoms of C and the concentration of atoms of
N.
[0222] FIGS. 14A to 14C illustrate capacitors 268a to 268c prepared
for an experiment, respectively. As illustrated in FIGS. 14A to
14C, the capacitors 268a to 268c were each formed by forming an
SiO.sub.2 film (silicon oxide film) 270 which is an insulating film
on a surface of a silicon (Si)-wafer 200, forming one of HfO.sub.2
films (hafnium oxide films) 272a to 272c which are insulating films
on the SiO.sub.2 film 270, forming a TiCN film 276 on one of the
HfO.sub.2 films 272a to 272c, and forming a TiN film (titanium
nitride film) 278 on the TiCN film 276.
[0223] In detail, an HF treatment was performed on the silicon
(Si)-wafer 200, the SiO.sub.2 film 270 was formed, each of the
HfO.sub.2 films 272a to 272c was formed, the TiCN film 276 was
formed, the TiN film 278 was formed, a cap TiN film was formed, a
gate was patterned, the gate was etched, a resist was removed, and
FGA was performed at 400.degree. C.
[0224] The TiCN film 276 was formed according to the sequence of
one of the previous embodiments. That is, the TiCN film 276 was
formed according to the film-forming flow of FIG. 4 and the gas
supply timing of FIG. 5 by using TiCl.sub.4 gas as a Ti-containing
gas, Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2 gas as a
C-containing gas, and NH.sub.3 gas as an N-containing gas. Here, in
the capacitors 268a to 268c of FIGS. 14A to 14C, the TiCN film 276
was formed by setting a number of sets to three, i.e., m=3, as in
Example 2, and the HfO.sub.2 films which are insulating films 272a
to 272c were formed to have different thicknesses.
[0225] A result of calculating work functions by plotting, on a
graph, effective work functions (eWFs) of equivalent oxide
thicknesses (EOTs) of the respective capacitors 268a to 268c is
illustrated in FIG. 15.
[0226] FIG. 15 is a graph that plots EOTs and effective work
functions (eWFs) of the TiCN films of the capacitors 268a to 268c.
Oxygen contained in a high-k film such as an HfO.sub.2 film is
diffused and discharged from the high-k film when a heat treatment
included in a process is performed, and thus an interface dipole is
formed on an interface between the high-k film and an interface
layer, thereby increasing an effective work function (eWF). A work
function of a TiN film is about 5.0 eV, including a work function
of the dipole, whereas a work function of the TiCN film 276
calculated from the graph of FIG. 15 is 4.55 eV to 4.68 eV as shown
in Table 2 below. Also, the work function
.PHI..sub.m=.PHI..sub.m,meas.-e.sub.dipole=4.24 eV to 4.37 eV when
considering an effect e.DELTA..sub.dipole of the dipole [0.31 eV,
quoted from Y. Kamimura et al., IEDM 2007, PP. 341-344]. As
described above, an experimental result revealed that a metal, the
threshold voltage Vth of which is adjustable by controlling the
concentration of C, i.e., a TiCN film as a metal film, the work
function of which is tunable, was provided. Thus, according to the
present invention, even when different work functions are required
according to a purpose, it was confirmed that a work function can
be adjusted using one film having a same element composition
ratio.
TABLE-US-00002 TABLE 2 .PHI..sub.m, means(eV) .PHI..sub.m(eV)
Example 1 4.68 4.37 Example 2 4.68 4.37 Example 3 4.55 4.24
[0227] Next, examples according to the fourth embodiment will be
described below but the present invention is not limited thereto.
In each of the following examples, a TiAlCN film was formed on the
wafer 200 (particularly, on an HfO film which is a high-k film)
according to the above sequence according to FIGS. 10 and 11.
Example 4
[0228] In Example 4, `X`, `Y` and `Z` described above were set to
`6`, `1` and `36`, respectively. That is, in Example 4, the TiAlCN
film was formed by alternately and repeatedly performing 36 times
(Z=36) forming a TiN layer six times (X=6) and forming an AlCTiN
layer once (Y=1).
[0229] In detail, in Example 4, the TiAlCN film was formed by
alternately and repeatedly performing 36 times a process of forming
a TiN layer by alternately supplying TiCl.sub.4 gas and NH.sub.3
gas six times and a process of forming an AlCTiN layer by supplying
TMA gas, TiCl.sub.4 gas and NH.sub.3 gas once. In this case,
process conditions in each of steps were set as follows.
[0230] <TiN Layer Forming Process>
[0231] (Step 21)
[0232] Temperature in process chamber: 350.degree. C.;
[0233] Pressure in process chamber: 45 Pa;
[0234] Feed rate of TiCl.sub.4 gas: 1.16 g/min; and
[0235] Duration for which TiCl.sub.4 gas was irradiated: 5
seconds
[0236] (Step 23)
[0237] Temperature in process chamber: 350.degree. C.;
[0238] Pressure in process chamber: 65 Pa;
[0239] Supply flow rate of NH.sub.3 gas: 7,500 sccm; and
[0240] Duration for which NH.sub.3 gas was irradiated: 15
seconds
[0241] <AlCTiN Layer Forming Process>
[0242] (Step 25)
[0243] Temperature in process chamber: 350.degree. C.;
[0244] Pressure in process chamber: 65 Pa;
[0245] Feed rate of TMA gas: 0.6 g/min; and
[0246] Duration for which TMA gas was irradiated: 6 seconds
[0247] (Step 27)
[0248] Temperature in process chamber: 350.degree. C.;
[0249] Pressure in process chamber: 45 Pa;
[0250] Feed rate of TiCl.sub.4 gas: 1.16 g/min; and
[0251] Duration for which TiCl.sub.4 gas was irradiated: 5
seconds
[0252] (Step 29)
[0253] Temperature in process chamber: 350.degree. C.;
[0254] Pressure in process chamber: 65 Pa;
[0255] Supply flow rate of NH.sub.3 gas: 7,500 sccm; and
[0256] Duration for which NH.sub.3 gas was irradiated: 15
seconds
[0257] The formed TiAlCN film had a film thickness of 10 nm, and a
30 nm TiN film was formed as a cap layer on the TiAlCN film.
Example 5
[0258] In Example 5, `X`, `Y` and `Z` described above were set to
`3`, `1` and `52`, respectively. That is, in Example 5, the TiAlCN
film was formed by alternately and repeatedly performing 52 times
(Z=52) forming a TiN layer three times (X=3) and forming an AlCTiN
layer once (Y=1).
[0259] In detail, in Example 5, the TiAlCN film was formed by
alternately and repeatedly performing 52 times a process of forming
a TiN layer by alternately supplying TiCl.sub.4 gas and NH.sub.3
gas three times and a process of forming an AlCTiN layer by
supplying TMA gas, TiCl.sub.4 gas and NH.sub.3 gas once. In this
case, process conditions in each of steps were set to be the same
as those in Example 4. Also, the TiAlCN film formed in Example 5
had a film thickness of 10 nm.
Example 6
[0260] In Example 6, `X`, `Y` and `Z` described above were set to
`1`, `1` and `78`, respectively. That is, in Example 6, the TiAlCN
film was formed by alternately and repeatedly performing 78 times
(Z=78) forming a TiN layer once (X=1) and forming an AlCTiN layer
once (Y=1).
[0261] In detail, in Example 6, the TiAlCN film was formed by
alternately and repeatedly performing 78 times a process of forming
a TiN layer by supplying TiCl.sub.4 gas and NH.sub.3 gas once and a
process of forming an AlCTiN layer by supplying TMA gas, TiCl.sub.4
gas and NH.sub.3 gas once. In this case, process conditions in each
of steps were set to be the same as those in Example 4. Also, the
TiAlCN film formed in Example 6 had a film thickness of 10 nm.
Example 7
[0262] In Example 7, `X`, `Y` and `Z` described above were set to
`0`, `1` and `100`, respectively. That is, in Example 7, the TiAlCN
film was formed by repeatedly performing 100 times (Z=100) forming
an AlCTiN layer once (Y=1) without forming a TiN layer (X=0).
[0263] In detail, in Example 7, the TiAlCN film was formed by
repeatedly performing 100 times a process of forming an AlCTiN
layer by supplying TMA gas, TiCl.sub.4 gas and NH.sub.3 gas once.
In this case, process conditions in each of steps were set to be
the same as those in Example 4. Also, the TiAlCN film formed in
Example 7 had a film thickness of 10 nm.
Example 8
[0264] In Example 8, `X`, `Y` and `Z` described above were set to
`1`, `0` and `340`, respectively. That is, in Example 8, the TiAlCN
film was formed by repeatedly performing 340 times (Z=340) forming
a TiN layer once (X=1) without forming an AlCTiN layer (Y=0).
[0265] In detail, in Example 8, the TiAlCN film was formed by
repeatedly performing 340 times a process of forming a TiN layer by
supplying TiCl.sub.4 gas and NH.sub.3 gas once. In this case,
process conditions in each of steps were set to be the same as
those in Example 4. Also, the TiAlCN film formed in Example 8 had a
film thickness of 10 nm.
[0266] FIG. 16 is a graph illustrating the relationship between an
EOT and a flat-band voltage Vfb of each of the metal films (the
TiAlCN films or the TiN films) formed according to Examples 4 to 8.
As illustrated in FIG. 16, the higher the ratio (concentration) of
C (or the lower the ratio (concentration) of N), the more the
flat-band voltage Vfb was shifted in a negative direction. When the
flat-band voltage Vfb was shifted in the negative direction, a work
function decreased.
[0267] FIG. 17 is a table illustrating the relationship between a
ratio between carbon (C) and nitrogen (N) and an effective work
function (eWF) of each of the metal films (the TiAlCN films or the
TiN films) formed according to Examples 4 to 8. FIG. 18A is a graph
illustrating a variation in a work function versus a ratio of
carbon (C) in each of the metal films (the TiAlCN films or the TiN
films) formed according to Examples 4 to 8. FIG. 18B is a graph
illustrating a variation in a work function versus a ratio of
nitrogen (N) in each of the metal films formed according to
Examples 4 to 8. A work function of a metal film was tuned by
adjusting `X`, `Y` and `Z` in the above examples, whereas FIGS. 17
to 18B illustrate effective work functions (eWFs) of gate
electrodes each including one of the metal films formed according
to the above examples. The effective work functions (eWFs) were
calculated from the threshold voltage Vfb, including a value of a
dipole formed at an interface between an HfO.sub.2 film and an
SiO.sub.2 film.
[0268] As illustrated in FIGS. 17, 18A and 18B, an effective work
function (eWF) decreased as the ratio of C contained in the TiAlCN
film (or the TiN film) increased, and increased as the ratio of N
contained in the TiAlCN film (or the TiN film) increased. The
dipole was determined by the type of a high-k film and was set to
have a constant value in the above examples. Thus, it may be
concluded that a work function of the TiAlCN film decreases as the
ratio of C in the TiAlCN film increases and increases as the ratio
of N in the TiAlCN film increases.
[0269] Oxygen contained in a high-k film such as an HfO.sub.2 film
is diffused and discharged from the high-k film when a heat
treatment included in a process is performed. Thus, an interface
dipole is formed on an interface between the high-k film and an
interface layer, thereby increasing an effective work function
(eWF). As illustrated in FIG. 17, a work function of the TiN film
which is a metal film according to Example 8 was about 5.0 eV,
including a work function of the dipole, whereas work functions of
the TiAlCN films which are metal films according to Examples 4 to 7
were 4.52 eV to 4.68 eV. Also, the work functions of the TiAlCN
films were about 4.21 eV to 4.37 eV when considering an effect
e.DELTA..sub.dipole of the dipole [0.31 eV, quoted from Y. Kamimura
et al., IEDM 2007, PP. 341-344]. It was confirmed that the work
function is tunable by controlling the ratio of C and/or N
contained in the TiAlCN films, based on the work functions of Ti
and Al, i.e., about 4.3 eV.
[0270] The inventors of the present application found that the work
functions of the TiAlN film and the TiN film which include Ti as a
metal element and do not include C as a metal element were about
4.6 eV to 4.7 eV and the work function of the TiAlC film that
includes Ti as a metal element and does not include N as a metal
element was about 4.1 eV. That is, the work function of the TiAlCN
film that includes Ti, C and N as metal elements may be tuned to a
desired value between the work function of the TiAlC film and the
work function of the TiAlN film (of the TiN film) by controlling
the ratios of C and N of the TiAlCN film.
[0271] As described above, an experimental result revealed that a
metal film, the threshold voltage Vth of which is adjustable by
controlling the ratio of C and/or N, i.e., a TiAlCN film which is a
metal film, the work function of which is tunable, was provided.
Thus, according to the present invention, even when different work
functions are required according to a purpose, it was confirmed
that a work function can be adjusted using one film having a same
element composition ratio.
[0272] Although an effective work function (eWF) can be tuned using
.phi.dipole or .phi.FLP (fermi-level pinning), a work function of a
metal film of a gate electrode is preferably tuned for the
following reasons.
[0273] The value of .phi.dipole is controlled according to a film
type of a high-k film or by diffusing Al or La to the high-k film
from a gate electrode. However, when the value of .phi.dipole is
controlled according to the film type of the high-k film, a dipole
value is shifted in the same direction in the case of a NMOS
transistor and a PMOS transistor (a dipole that is shifted in a
negative direction is required in the NMOS transistor and a dipole
that is shifted in a positive direction is required in the PMOS
transistor). Thus, a high-k film for the NMOS transistor and a
high-k film for the PMOS transistor should be formed separately,
and thus, a process becomes complicated. Also, when the value of
.phi.dipole is controlled by diffusing Al or La to the high-k film
from the gate electrode, a heat treatment should be performed at
about 1,000.degree. C. However, when the high-k film is used, the
heat treatment performed at about 1,000.degree. C. (which is
generally a gate-last process) is performed before a gate stack
(including an electrode, the high-k film, an SiO.sub.2 film and a
Si-substrate) is formed. Also, the heat treatment is performed to
activate a source and drain. Thus, in the gate-last process, any
heat treatment performed at about 1,000.degree. C. is not
preferably performed after the gate stack is formed. Although
.phi.dipole should be increased to increase a degree to which an
effective work function (eWF) is tuned, mobility (a moving speed of
electrons or holes) may decrease when .phi.dipole increases. Also,
although the value of .phi.FLP can be controlled by adding silicon
(Si) to an electrode, the electrode may have a high resistance
value. Thus, the work function of a metal film is preferably
tuned.
[0274] Hereinafter, exemplary embodiments according to the present
invention are supplementarily noted.
[0275] According to the present invention, a work function may be
adjusted while securing affinity with a process in terms of
integration with a technique generally used in the art.
[0276] <Supplementary Note 1>
[0277] According to an aspect of the present invention, there is
provided a method of manufacturing a semiconductor device,
including: forming a film having a predetermined thickness and
containing a first metal element, carbon and nitrogen on a
substrate by: (a) forming a first layer containing the first metal
element and carbon by supplying a metal-containing gas containing
the first metal element and a carbon-containing gas to the
substrate M times and (b) forming a second layer containing the
first metal element, carbon and nitrogen by supplying a
nitrogen-containing gas to the substrate having the first layer
formed thereon N times to nitride the first layer, wherein M and N
are selected in a manner that a work function of the film has a
predetermined value (where M and N are natural numbers).
[0278] <Supplementary Note 2>
[0279] Preferably, the first metal element includes one selected
from the group consisting of tantalum, cobalt, tungsten,
molybdenum, ruthenium, yttrium, lanthanum, zirconium and
hafnium.
[0280] <Supplementary Note 3>
[0281] Preferably, the metal-containing gas includes one selected
from the group consisting of TiCl.sub.4 and TaCl.sub.4.
[0282] <Supplementary Note 4>
[0283] Preferably, the carbon-containing gas includes
Hf[C.sub.5H.sub.4(CH.sub.3)].sub.2(CH.sub.3).sub.2.
[0284] <Supplementary Note 5>
[0285] Preferably, the carbon-containing gas includes a second
metal element different from the first metal element.
[0286] <Supplementary Note 6>
[0287] Preferably, the second metal element includes hafnium.
[0288] <Supplementary Note 7>
[0289] Preferably, the work function of the film is increased by
selecting M greater than N.
[0290] <Supplementary Note 8>
[0291] Preferably, a concentration of carbon in the film is
controlled by selecting M and N to adjust the work function of the
film to be the predetermined value.
[0292] <Supplementary Note 9>
[0293] According to another aspect of the present invention, there
is provided a method of manufacturing a semiconductor device,
including: forming a film having a predetermined thickness and
containing a metal element, carbon and nitrogen on a substrate by:
(a) supplying a metal-containing gas containing the metal element
to the substrate M times; (b) supplying a carbon-containing gas to
the substrate N times; and (c) supplying a nitrogen-containing gas
to the substrate L times, wherein M, N and L are selected in a
manner that a work function of the film has a predetermined value
(where M, N and L are natural numbers).
[0294] <Supplementary Note 10>
[0295] According to another aspect of the present invention, there
is provided a method of manufacturing a semiconductor device,
including: forming a film having a predetermined thickness and
containing a first metal element, a second metal element and carbon
on a substrate by: (a) forming a first layer containing the first
metal element by supplying a first metal-containing gas containing
the first metal element to the substrate M times and (b) forming a
second layer containing the first metal element, the second metal
element and carbon by supplying a second metal-containing gas
containing the second metal element and carbon to the substrate
having the first layer formed thereon N times, wherein M and N are
selected in a manner that a work function of the film has a
predetermined value (where M and N are natural numbers).
[0296] <Supplementary Note 11>
[0297] Preferably, the first metal element includes one selected
from the group consisting of titanium and tantalum, and the second
metal element includes aluminium.
[0298] <Supplementary Note 12>
[0299] Preferably, the first metal-containing gas includes one
selected from the group consisting of TiCl.sub.4 and TaCl.sub.4,
and the second metal-containing gas includes trimethylaluminium
(TMA).
[0300] <Supplementary Note 13>
[0301] According to still another aspect of the present invention,
there is provided a substrate processing apparatus including: a
process chamber configured to accommodate a substrate; a
metal-containing gas supply system configured to supply a
metal-containing gas containing a metal element to the substrate in
the process chamber; a carbon-containing gas supply system
configured to supply a carbon-containing gas to the substrate in
the process chamber; a nitrogen-containing gas supply system
configured to supply a nitrogen-containing gas to the substrate in
the process chamber; and a control unit configured to control the
metal-containing gas supply system, the carbon-containing gas
supply system and the nitrogen-containing gas supply system to form
a film having a predetermined thickness and containing the metal
element, carbon and nitrogen on the substrate by: (a) forming a
first layer containing the metal element and carbon by supplying
the metal-containing gas and the carbon-containing gas to the
substrate M times; and (b) forming a second layer containing the
metal element, carbon and nitrogen by supplying the
nitrogen-containing gas to the substrate having the first layer
formed thereon N times to nitride the first layer, wherein M and N
are selected in a manner that a work function of the film has a
predetermined value (where M and N are natural numbers).
[0302] <Supplementary Note 14>
[0303] According to still another aspect of the present invention,
there is provided a substrate processing apparatus including: a
process chamber configured to accommodate a substrate; a first
metal-containing gas supply system configured to supply a first
metal-containing gas containing a first metal element to the
substrate in the process chamber; a second metal-containing gas
supply system configured to supply a second metal-containing gas
containing a second metal element and carbon to the substrate in
the process chamber; and a control unit configured to control the
first metal-containing gas supply system and the second
metal-containing gas supply system to form a film having a
predetermined thickness and containing the first metal element, the
second metal element and carbon on the substrate by: (a) forming a
first layer containing the first metal element by supplying the
first metal-containing gas to the substrate M times; and (b)
forming a second layer containing the first metal element, the
second metal element and carbon by supplying the second
metal-containing gas to the substrate having the first layer formed
thereon N times, wherein M and N are selected in a manner that a
work function of the film has a predetermined value (where M and N
are natural numbers).
[0304] <Supplementary Note 15>
[0305] According to still another aspect of the present invention,
there is provided a program causing a computer to perform forming a
film having a predetermined thickness and containing a metal
element, carbon and nitrogen on a substrate in a process chamber of
a substrate processing apparatus by: (a) forming a first layer
containing the metal element and carbon by supplying a
metal-containing gas containing the metal element and a
carbon-containing gas to the substrate M times and (b) forming a
second layer containing the first metal element, carbon and
nitrogen by supplying a nitrogen-containing gas to the substrate
having the first layer formed thereon N times to nitride the first
layer, wherein M and N are selected in a manner that a work
function of the film has a predetermined value (where M and N are
natural numbers).
[0306] <Supplementary Note 16>
[0307] According to still another aspect of the present invention,
there is provided a program causing a computer to perform: forming
a film having a predetermined thickness and containing a first
metal element, a second metal element and carbon on a substrate in
a process chamber of a substrate processing apparatus by: (a)
forming a first layer containing the first metal element by
supplying a first metal-containing gas containing the first metal
element to the substrate M times and (b) forming a second layer
containing the first metal element, the second metal element and
carbon by supplying a second metal-containing gas containing the
second metal element and carbon to the substrate having the first
layer formed thereon N times, wherein M and N are selected in a
manner that a work function of the film has a predetermined value
(where M and N are natural numbers).
[0308] <Supplementary Note 17>
[0309] According to another aspect of the present invention, there
is provided a non-transitory computer-readable recording medium
storing a program causing a computer to perform: forming a film
having a predetermined thickness and containing a metal element,
carbon and nitrogen on a substrate in a process chamber of a
substrate processing apparatus by: (a) forming a first layer
containing the metal element and carbon by supplying a
metal-containing gas containing the metal element and a
carbon-containing gas to the substrate M times and (b) forming a
second layer containing the first metal element, carbon and
nitrogen by supplying a nitrogen-containing gas to the substrate
having the first layer formed thereon N times, wherein M and N are
selected in a manner that a work function of the film has a
predetermined value (where M and N are natural numbers).
[0310] <Supplementary Note 18>
[0311] According to another aspect of the present invention, there
is provided a non-transitory computer-readable recording medium
storing a program causing a computer to perform: forming a film
having a predetermined thickness and containing a first metal
element, a second metal element and carbon on a substrate in a
process chamber of a substrate processing apparatus by: (a) forming
a first layer containing the first metal element by supplying a
first metal-containing gas containing the first metal element to
the substrate M times and (b) forming a second layer containing the
first metal element, the second metal element and carbon by
supplying a second metal-containing gas containing the second metal
element and carbon to the substrate having the first layer formed
thereon N times, wherein M and N are selected in a manner that a
work function of the film has a predetermined value (where M and N
are natural numbers).
[0312] <Supplementary Note 19>
[0313] According to another aspect of the present invention, there
is provided a method of manufacturing a semiconductor device,
including: (a) exposing a substrate to a nitrogen-containing gas;
and (b) exposing the substrate to a titanium-containing gas and a
carbon-containing gas alternately, wherein (b) is performed at
least twice after (a) is performed once, thereby increasing a
carbon concentration in a titanium carbonitride film.
[0314] <Supplementary Note 20>
[0315] Preferably, the substrate is exposed to the
titanium-containing gas prior to the carbon-containing gas when (b)
is performed at least twice.
[0316] <Supplementary Note 21>
[0317] According to another aspect of the present invention, there
is provided a method of manufacturing a semiconductor device,
including: forming a metal film containing carbon and nitrogen in a
predetermined ratio on a substrate by: (a) forming a first layer
containing a metal element and one of carbon and nitrogen M times
and (b) forming a second layer containing the metal element,
nitrogen and carbon N times, wherein (a) and (b) are alternately
performed L times (where M, N and L are natural numbers).
[0318] <Supplementary Note 22>
[0319] According to another aspect of the present invention, there
is provided a method of manufacturing a semiconductor device,
including: forming a metal film containing carbon and nitrogen in a
predetermined ratio on a substrate by: (a) supplying a first source
containing a metal element and a second source containing one of
carbon and nitrogen alternately M times to the substrate and (b)
supplying a third source containing carbon, a fourth source
containing the metal element and a fifth source containing nitrogen
N times, wherein (a) and (b) are alternately performed L times
(where M, N and L are natural numbers).
[0320] <Supplementary Note 23>
[0321] In the method of any one of Supplementary notes 21 and 22,
preferably, M, N and L are determined by a ratio of at least one of
nitrogen and carbon contained in the metal film.
[0322] <Supplementary Note 24>
[0323] In the method of Supplementary note 21, preferably, the
second layer includes a second metal element different from the
metal element.
[0324] <Supplementary Note 25>
[0325] In the method of Supplementary note 22, preferably, the
fourth source includes a second metal element different from the
metal element.
[0326] <Supplementary Note 26>
[0327] In the method of any one of Supplementary notes 21 through
25, the metal film is film-formed on a high-k dielectrics film
formed on the substrate.
[0328] <Supplementary Note 27>
[0329] In the method of any one of Supplementary notes 21 through
26, the metal element includes one selected from the group
consisting of titanium, tantalum, hafnium, zirconium, molybdenum
and tungsten.
[0330] <Supplementary Note 28>
[0331] In the method of any one of Supplementary notes 24 and 25,
the second metal element includes aluminium.
[0332] <Supplementary Note 29>
[0333] In the method of Supplementary note 22, the first source and
the fourth source includes TiCl.sub.4.
[0334] <Supplementary Note 30>
[0335] In the method of Supplementary note 25, the third source
includes trimethylaluminium (TMA).
[0336] <Supplementary Note 31>
[0337] In the method of any one of Supplementary notes 21 through
30, the metal element includes titanium and a work function of the
metal film is a value between a work function of TiAlC and one of a
work function of TiN and a work function of TiAlN.
[0338] <Supplementary Note 32>
[0339] In the method of any one of Supplementary notes 24 and 25,
the metal element includes titanium, the second metal element
includes aluminium, and a work function of the metal film is a
value between a work function of TiAlC and one of a work function
of TiN and a work function of TiAlN.
[0340] <Supplementary Note 33>
[0341] According to another aspect of the present invention, there
is provided a substrate processing method including: forming a
metal film containing carbon and nitrogen in a predetermined ratio
on a substrate by: (a) forming a first layer containing a metal
element and one of carbon and nitrogen M times and (b) forming a
second layer containing the metal element, nitrogen and carbon N
times, wherein (a) and (b) are alternately performed L times (where
M, N and L are natural numbers).
[0342] <Supplementary Note 34>
[0343] According to another aspect of the present invention, there
is provided a substrate processing method including: forming a
metal film containing carbon and nitrogen in a predetermined ratio
on a substrate by: (a) supplying a first source containing a metal
element and a second source containing one of carbon and nitrogen
alternately M times to the substrate and (b) supplying a third
source containing carbon, a fourth source containing the metal
element and a fifth source containing nitrogen N times, wherein (a)
and (b) are alternately performed L times (where M, N and L are
natural numbers).
[0344] <Supplementary Note 35>
[0345] In the substrate processing method of any one of
Supplementary notes 33 and 34, preferably, M, N and L are
determined by a ratio of at least one of nitrogen and carbon
contained in the metal film.
[0346] <Supplementary Note 36>
[0347] According to another aspect of the present invention, there
is provided a substrate processing apparatus including: a process
chamber configured to accommodate a substrate; a metal-containing
source supply system connected to the process chamber and
configured to supply a metal-containing source containing a metal
element to the substrate accommodated in the process chamber; a
nitrogen-containing source supply system connected to the process
chamber and configured to supply a nitrogen-containing source to
the substrate accommodated in the process chamber; a
carbon-containing source supply system connected to the process
chamber and configured to supply a carbon-containing source to the
substrate accommodated in the process chamber; and a control unit
connected to the metal-containing source supply system, the
nitrogen-containing source supply system and the carbon-containing
source supply system and configured to control the metal-containing
source supply system, the nitrogen-containing source supply system
and the carbon-containing source supply system to form a metal film
containing nitrogen and carbon in a predetermined ratio on the
substrate accommodated in the process chamber by: (a) supplying the
metal-containing source and one of the nitrogen-containing source
and the carbon-containing source alternately M times to the
substrate accommodated in the process chamber and (b) supplying the
metal-containing source, the nitrogen-containing source and the
carbon-containing source N times, wherein (a) and (b) are
alternately performed L times (where M, N and L are natural
numbers).
[0348] <Supplementary Note 37>
[0349] In the substrate processing apparatus of Supplementary note
36, preferably, M, N and L are determined by a ratio of at least
one of nitrogen and carbon contained in the metal film.
[0350] <Supplementary Note 38>
[0351] According to another aspect of the present invention, there
is provided a program causing a computer to perform: forming a
metal film containing carbon and nitrogen in a predetermined ratio
on a substrate by: (a) forming a first layer containing a metal
element and one of carbon and nitrogen M times and (b) forming a
second layer containing the metal element, nitrogen and carbon N
times, wherein (a) and (b) are alternately performed L times (where
M, N and L are natural numbers).
[0352] <Supplementary Note 39>
[0353] In the program of Supplementary note 39, preferably, M, N
and L are determined by a ratio of at least one of nitrogen and
carbon contained in the metal film.
[0354] <Supplementary Note 40>
[0355] According to another aspect of the present invention, there
is provided a non-transitory computer-readable recording medium
storing a program causing a computer to perform: forming a metal
film containing carbon and nitrogen in a predetermined ratio on a
substrate by: (a) forming a first layer containing a metal element
and one of carbon and nitrogen M times and (b) forming a second
layer containing the metal element, nitrogen and carbon N times,
wherein (a) and (b) are alternately performed L times (where M, N
and L are natural numbers).
[0356] <Supplementary Note 41>
[0357] In the non-transitory computer-readable recording medium of
Supplementary note 40, preferably, M, N and L are determined by a
ratio of at least one of nitrogen and carbon contained in the metal
film.
[0358] As described above, the present invention is applicable to,
for example, a method of manufacturing a semiconductor device, a
substrate processing apparatus configured to process a substrate
such as a semiconductor wafer or a glass substrate, etc.
* * * * *