U.S. patent application number 14/463756 was filed with the patent office on 2015-07-30 for plasma processing apparatus.
This patent application is currently assigned to Hitachi High-Technologies Corporation. The applicant listed for this patent is Hitachi High-Technologies Corporation. Invention is credited to Masatoshi Kawakami, Hideki Kihara, Hiroho Kitada, Hironori Kusumoto, Tsutomu Nakamura, Hidenobu Tanimura.
Application Number | 20150214083 14/463756 |
Document ID | / |
Family ID | 53679701 |
Filed Date | 2015-07-30 |
United States Patent
Application |
20150214083 |
Kind Code |
A1 |
Kawakami; Masatoshi ; et
al. |
July 30, 2015 |
PLASMA PROCESSING APPARATUS
Abstract
In a plasma processing apparatus, an additional viewing window
is disposed between an infrared temperature sensor and a view
window, and the additional viewing window is cooled to be retained
at room temperature (20.degree. C. to 25.degree. C.), to reduce and
to stabilize electromagnetic waves emitted from the viewing window.
By correcting the value of the electromagnetic waves, the
measurement precision of the temperature monitor is increased and
it is possible to measure and to control the dielectric window
temperature in a stable state.
Inventors: |
Kawakami; Masatoshi; (Tokyo,
JP) ; Nakamura; Tsutomu; (Tokyo, JP) ; Kihara;
Hideki; (Tokyo, JP) ; Kitada; Hiroho; (Tokyo,
JP) ; Tanimura; Hidenobu; (Tokyo, JP) ;
Kusumoto; Hironori; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hitachi High-Technologies Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
Hitachi High-Technologies
Corporation
|
Family ID: |
53679701 |
Appl. No.: |
14/463756 |
Filed: |
August 20, 2014 |
Current U.S.
Class: |
156/345.27 ;
374/121 |
Current CPC
Class: |
H01L 21/67248 20130101;
H01J 37/32807 20130101; G01J 5/061 20130101; G01J 5/06 20130101;
H01J 37/32522 20130101; G01J 5/0875 20130101; G01J 5/042 20130101;
H01J 37/32192 20130101; H01J 37/32935 20130101 |
International
Class: |
H01L 21/67 20060101
H01L021/67; H01J 37/32 20060101 H01J037/32; G01J 5/08 20060101
G01J005/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 28, 2014 |
JP |
2014-012917 |
Claims
1. A plasma processing apparatus, comprising: a processing chamber
disposed in a vacuum container; gas supply means for supplying gas
to the processing chamber; a sample stage which is disposed in the
processing chamber and on which a sample to be processed is
mounted; a planar member comprising a dielectric material which is
disposed above the processing chamber to cover the processing
chamber and through which an electric field supplied to form plasma
in the processing chamber passes; an electric field supply path
disposed outside the processing chamber for supplying the electric
field to the planar member; an infrared sensor disposed on the
outside the planar member apart therefrom for receiving an infrared
ray emitted from the planar member and for thereby detecting
temperature of the planar member; a first window member disposed
between the planar member and the infrared sensor; and a second
window member disposed between the planar member and the infrared
sensor to be apart from the first window member, the first and
second window members comprising one and the same material,
wherein: temperature of the second window member is in a
predetermined range; and at reception of the infrared ray having
passed through the first and second window members, the infrared
sensor detects the temperature of the planar member.
2. The plasma processing apparatus according to claim 1, wherein
the temperature of the planar member is detected by correcting an
output obtained from the infrared sensor according to the
temperature of the second window member.
3. The plasma processing apparatus according to claim 1, wherein
the temperature of the planar member is adjusted according to a
condition of processing on the sample.
4. The plasma processing apparatus according to claim 2, wherein
the temperature of the planar member is adjusted according to a
condition of processing on the sample.
5. A temperature sensor comprising an infrared sensor for receiving
an infrared ray emitted from an object for temperature detection,
and for thereby detecting the temperature, a first window member
disposed between a planar member and the infrared sensor; and a
second window member disposed between the planar member and the
infrared sensor to be apart from the first window member, wherein:
the first and second window member comprising one and the same
material, temperature of the second window member is in a
predetermined range; and at reception of an infrared ray having
passed through the first and second window member, the infrared
sensor detects the temperature of the planar member.
6. The temperature sensor according to claim 5, wherein the
temperature of the planar member is detected by correcting an
output obtained from the infrared sensor according to the
temperature of the second window member.
7. The temperature sensor according to claim 5, wherein the
temperature of the planar member is adjusted according to a
condition of processing on a sample.
8. The temperature sensor according to claim 6, wherein the
temperature of the planar member is adjusted according to a
condition of processing on a sample.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a plasma processing
apparatus for processing a sample such as a semiconductor wafer
placed in a processing chamber, in a vacuum container, by use of
plasma formed in the processing chamber, and in particular, to a
plasma processing apparatus for processing a sample while adjusting
temperature of a member configuring a wall of the processing
chamber.
[0002] Due to the recent development of finer semiconductor
devices, in an etching process to copy, onto a lower layer, a mask
formed by lithography, there is required high dimensional
precision, namely, precision of Critical Dimension (CD). In the
mass-production of such semiconductor devices, it is important to
secure reproducibility of CD in addition to high CD
controllability.
[0003] In general, the critical dimension deviates in the etching
process due to factors such as adhesion of byproducts from
materials to be processed, onto inner walls of the etching chamber,
wear of inner members of the chamber due to long-period use
thereof, and variation in the plasma state affecting etching
performance due to change in the adhesion probability of radicals
onto inner walls or the like of the chamber caused by variation in
temperature or the like of inner members of the chamber.
[0004] In some plasma processing apparatuses heat of the prior art,
to suppress variation in inner temperature of the chamber, outer
walls of the vacuum chamber are heated by use of a conversion
heater. Further, in some other plasma processing apparatuses of the
conventional technique, window members or the like made of
dielectrics arranged in waveguide paths of an electric field and a
magnetic field wherein it is to be avoided to dispose any items
which adversely affect propagation of electric and magnetic fields
such as microwaves to generate plasma, are heated by blowing a warm
wind thereto.
[0005] According to the techniques, in order to adjust temperature
with high precision, it is required that temperature of the target
of temperature adjustment is detected to adjust the quantity of
heat of the heater and the temperature of the warm wind based on
the results of detection. However, it is desired to avoid
installation of a contact-type thermometer which disturbs the
electric or magnetic field as above. Hence, there has been employed
an apparatus to detect temperature in a contactless manner, for
example, a radiation thermometer. Further, when detecting
temperature by the radiation thermometer, a viewing window is
disposed between the thermometer and a target of temperature
detection such as a window member to face the target (or to
overlook the target), the viewing window passing therethrough
infrared rays emitted from the target.
[0006] JP-A-8-250293 describes a technique in which a dielectric
material such as alumina is used to form members configuring inner
wall surfaces of the vacuum chamber or to form surfaces of the wall
surface members, and a window made of quartz is disposed to face
the processing chamber; and temperature of the inner wall surface
members is detected by an infrared thermometer via the window to
control the temperature of plasma-tolerant walls with high
precision, to thereby stabilize the processing which is conducted
by use of plasma.
SUMMARY OF THE INVENTION
[0007] The conventional techniques are accompanied with a problem
since consideration has not been fully given to the following
point. Specifically, in the conventional techniques employing an
apparatus such as the radiation thermometer to detect temperature
in a contactless manner by use of electromagnetic waves in a band
of a particular wavelength, consideration has not been given to
influence of electromagnetic waves emitted from the viewing window
itself.
[0008] When the viewing window receives heat through radiation or
conduction to be heated and temperature thereof goes up, members of
the viewing window emit electromagnetic waves such as infrared rays
and far-infrared rays. Hence, the thermometer to detect temperature
by receiving electromagnetic waves through the viewing window
naturally receives electromagnetic waves passing through the
viewing window and electromagnetic waves emitted from the viewing
window. As a result, the thermometer detect the temperature based
on the quantity of electromagnetic waves different from that of
electromagnetic waves corresponding the actual temperature of the
member as the target of temperature detection, deteriorating the
detection precision This point has not been taken into
consideration in the conventional techniques.
[0009] It is therefore an object of the present invention to
provide a plasma processing apparatus in which temperature of
members configuring a target device is detected with higher
precision to more stably adjust the temperature, to thereby
increasing stability of plasma processing.
[0010] To achieve the object according to the present invention,
there is provided a plasma processing apparatus comprising: [0011]
a processing chamber which is connected to a vacuum pumping
apparatus and an inside of which can be decompressed, the
processing chamber being sealed by a dielectric window and a vacuum
container; [0012] a gas supply apparatus for supplying gas in the
processing chamber; a substrate electrode on which a member to be
processed can be mounted and temperature of which can be controlled
by a temperature controller; [0013] high-frequency wave supply
means for supplying, via the dielectric window, electromagnetic
waves to generate plasma; [0014] means for forming a magnetic field
to generate the plasma; [0015] a high-frequency power supply
connected to the high-frequency wave supply means; [0016] an
infrared radiation temperature sensor for monitoring temperature of
the dielectric window; [0017] a warm-wind heater for supplying a
warm wind to the dielectric window; [0018] a function to adjust the
temperature of the dielectric window based on a signal measured by
the infrared radiation temperature sensor, the plasma processing
apparatus further comprising, in order that the infrared radiation
temperature sensor is installed at a position where magnetic flux
density is equal to or less than one tenth of magnetic flux density
in a coil: [0019] a metallic mesh disposed on an upper surface of a
cavity resonator for preventing leakage of a microwave; [0020] a
viewing window for passing an infrared ray therethrough; [0021] a
perpendicular viewing hole disposed in a waveguide for viewing an
inside of the viewing window by the infrared radiation temperature
sensor; and [0022] a support stage for supporting the infrared
radiation temperature sensor from the waveguide to provide a
distance from the coil, wherein [0023] an additional viewing window
is arranged between the infrared radiation temperature sensor and
the viewing window, the additional viewing window is cooled to be
retained at a room temperature (20.degree. C. to 25.degree. C.) to
reduce and to stabilize an electromagnetic wave emitted from the
additional window itself, a value of the electromagnetic wave is
corrected to increase measuring precision of a temperature monitor,
to measure and to control the temperature of the dielectric window
in a stable state.
[0024] According to the present invention, there is obtained an
advantage in which electromagnetic waves emitted from the viewing
window are reduced and are stabilized, and the value thereof is
corrected, to thereby increase measuring precision of the
temperature monitor
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a longitudinal cross-sectional view showing an
outline of a configuration of a plasma processing apparatus
according to an embodiment of the present invention;
[0026] FIG. 2 is a longitudinal cross-sectional view showing a
magnified image of an upper section of the plasma processing
apparatus shown in FIG. 1;
[0027] FIG. 3 is a graph showing an optical characteristic of a
viewing window according to the embodiment shown in FIG. 1;
[0028] FIG. 4 is a graph showing a change in light emission
intensity of infrared rays of a particular body for each
wavelength;
[0029] FIG. 5 is a graph showing the radiance detected by an
infrared temperature sensor when there does not exist an additional
viewing window according to the embodiment shown in FIG. 2;
[0030] FIG. 6 is a graph showing an optical characteristic of the
additional viewing window according to the embodiment shown in FIG.
2;
[0031] FIG. 7 is a graph showing the radiance detected by an
infrared temperature sensor 191 when the additional viewing window
according to the embodiment shown in FIG. 2 is disposed;
[0032] FIG. 8 is a graph showing magnitude of a change in the
radiance with respect to a change in temperature of viewing windows
123 and 129 according to the embodiment shown in FIG. 2; and
[0033] FIG. 9 is a graph showing a method of correcting, by use of
the radiance of the viewing windows, the output or the detection
value of the infrared temperature sensor according to the
embodiment shown in FIG. 2.
DESCRIPTION OF THE EMBODIMENTS
[0034] Next, description will be given of an embodiment of the
present invention by referring to the drawings.
Embodiment 1
[0035] Referring now to the drawings, description will be given of
an embodiment of the present invention FIGS. 1 and 2 show a plasma
processing apparatus according to an embodiment of the present
invention. Particularly, in this embodiment, the apparatus is a
plasma processing apparatus to conduct microwave Electron Cyclotron
Resonance (ECR) etching.
[0036] FIG. 1 shows, in a longitudinal cross-sectional view, an
outline of a configuration of the plasma processing apparatus
according to an embodiment of the present invention. In FIG. 1, the
plasma processing apparatus has a cylindrical contour or a contour
to be regarded as a cylindrical contour. On an upper section of a
cylindrical sidewall of a vacuum container 101 is open. Over the
upper section, a disk-contour dielectric window 103 made of for
example, quartz is installed. By sealing the gap between the vacuum
container 101 and the dielectric window 103, the inside thereof is
sealed up to an airtight state.
[0037] Below the dielectric window 103, there is disposed a shower
plate 102 made of for example, quartz or yttria in which a
plurality of through holes are arranged to feed etching gas into
the processing chamber 104 in the vacuum container 10. The
processing chamber 104 is configured in a state in which the
ceiling surface thereof is sealed up in an airtight state between
the dielectric window 103 and the sidewall of the vacuum container
101. The bottom surface of the processing chamber 104 is configured
using the shower plate 102, which faces plasma formed in the
processing chamber 104. During the etching process, heat is
imparted from the plasma via the shower plate 102 to the dielectric
window 103 arranged thereover.
[0038] Between the shower plate 102 and the dielectric window 103,
a space is formed as shown in FIG. 1. The space is communicatively
connected to a gas supply 105 to flow etching gas. Etching gas fed
from the gas supply 105 diffuses in the space and is then delivered
via the through holes of the shower plate 102 to the processing
chamber 104. Below the vacuum container 101, a vacuum pumping
apparatus, not shown, is disposed to be communicatively connected
to the processing chamber 104 via a vacuum pumping hole 106
disposed in the bottom surface of the processing chamber 104 in the
vacuum container 101.
[0039] To supply the processing chamber 104 with power to generate
plasma, a waveguide or an antenna 107 is disposed as a high
frequency emitting apparatus above the dielectric window 103 to
emit electromagnetic waves. The waveguide 107 includes a
cylindrical tube-shaped section extending upward above the
dielectric window 103. In the tube-shaped section, a dielectric
plate 121 made of for example, quartz is arranged to adjust the
distribution of electromagnetic waves in the processing chamber 104
below the dielectric window 103.
[0040] The cylindrical tube-shaped section extending in the
longitudinal direction of waveguide 107 includes an upper end
section which is connected to one end section of a horizontally
extending tube-shaped section having a rectangular cross section,
and is resultantly changed in the extending direction. On the other
end side of the tube-shaped section having a rectangular cross
section, a power supply 109 is disposed to generate electromagnetic
waves to be transmitted to the inside of the waveguide 107. The
frequency of the electromagnetic waves is not particularly limited,
but a 2.45 GHz microwave is employed in the present embodiment.
[0041] In the outer circumferential section of the processing
chamber 104 above the dielectric window 103 and on the outer
circumferential side of the sidewall of the cylindrical section of
the vacuum container 101, a magnetic field generating coil 110 is
arranged to form a magnetic field. An electric field which is
generated from the electromagnetic wave generating power supply 109
and which is fed via the waveguide 107, the dielectric window 103,
and the shower plate 102 to the processing chamber 104 reacts with
a magnetic field which is generated by the magnetic field
generating coil 110 when a direct current is supplied. The reaction
excites particles of the etching gas to form plasma in a space
below the shower plate 102 in the processing chamber 104. According
to the present embodiment, in the lower section of the processing
chamber 104 and below the shower plate 102, a sample stage having
an electrode therein 111 is disposed to face the bottom surface of
the shower plate 102.
[0042] In the present embodiment, the sample stage 111 is
configured in a substantially cylindrical contour and includes an
upper surface on which a wafer 112 to be processed is to be
mounted. On the upper surface, a film made of dielectric, not
shown, formed by spraying is disposed. In the dielectric film, at
least one film-shaped electrode is arranged and is connected via a
high-frequency filter 115 to a direct-current (dc) power supply 116
to supply dc power to the electrode. In the sample stage 111, a
disk-shaped substrate made of a conductor is disposed and is
connected via a matching circuit 113 to a high-frequency power
supply 114.
[0043] In such plasma processing apparatus, a vacuum container 101
is coupled to a sidewall of a second vacuum container 101, not
shown, in the vacuum container 101, a vacuum transfer chamber in
which transfer devices such as a robot arm are disposed in a
decompressed transfer chamber. A wafer 112 transferred through the
transfer chamber into the processing chamber 104 is
electrostatically chucked onto the sample stage 111 by
electrostatic force of the dc voltage applied from the dc power
supply 116. A predetermined etching gas is then supplied from the
gas supply 105 to the processing chamber 104 and the internal
pressure of the processing chamber 104 is adjusted to the pressure
suitable for the processing. Thereafter, the electric field and the
magnetic field are formed in the processing chamber 104, to
generate plasma in a space between the sample stage 111 and the
shower plate 102 in the processing chamber 104. In the state in
which the plasma is generated, high-frequency power is applied from
the high-frequency power supply 114 connected to the sample stage
111, to form bias potential above the wafer 112. Hence, charged
particles in the plasma are drawn onto the surface of the wafer
112, to thereby etch a target film disposed on the surface of the
wafer 112.
[0044] During the etching process, to control temperature of the
dielectric window 103 and the shower plate 102, a warm-wind heater
117 is disposed as a heater for the dielectric window 103 and the
shower plate 102. Specifically, in the member configuring the
ceiling surface corresponding to the upper surface of the cylinder
of a cavity resonator 108 which is disposed above the dielectric
window 103 and between the dielectric window 103 and the waveguide
107 and which has a cylindrical space therein, there is disposed
the heater 117 which is connected to a gas line to pass
therethrough dry air at the room temperature and which heats up the
dry air supplied thereto, to a desired temperature to supply the
heated dry air to a cylindrical sealed space 128, to thereby heat
the dielectric window 103 and the shower plate 102. Further, the
heater (17 is connected to a warm-wind heater controller 118.
[0045] The dry air heated by the heater 117 is fed into the
waveguide via a gas supply hole disposed in the member configuring
the ceiling surface of the cavity resonator 108. The dry air makes
contact with the dielectric window 103 to impart heat thereto, and
the dielectric window 103 is hence heated. Though heat conduction,
the shower plate 102 disposed therebelow is also heated.
[0046] In the ceiling surface of the cavity resonator 108, there is
disposed a ring-shaped member having a ring-shaped groove to
configure a cooling water path 120 through which water flows. The
dielectric window 103 may also be cooled when the dry air is
supplied at the room temperature without heating the dry air by the
heater 117 and heat is exhausted from the cooling water passing
through the cooling water path 120. As a result, it is possible to
heat or to cool the dielectric window 103 by tuning the heater 117
on or off.
[0047] The dry air fed to the space 128 flows upward through the
cylindrical section of the waveguide 107 connected to the space 128
in the upper central section of the space 128 and is exhausted to
the outside of the waveguide 107 through an exhaust port 122
disposed on an upper surface of the connecting section between the
rectangular cross-sectional section and the cylindrical section of
the waveguide 107. For this purpose, the dielectric plate 121
arranged in the cylindrical section of the waveguide 107 is
configured to pass dry air therethrough.
[0048] To measure and to monitor temperature of the dielectric
window 103, an infrared radiation temperature sensor 119 is
installed on the outer side of the waveguide 107. The temperature
sensor 119 transmits a signal indicating the temperature thus
sensed, via a communicating device to the warm-wind heater
controller 118. Based on the signal, the heater controller 118
compares the resultant temperature of the dielectric window 103
with a predetermined setting temperature. According to the
comparison result, in order that the dielectric window 103 is set
to a desired temperature, the heater controller 118 generates a
signal to turn the heater 117 on or off to thereby adjust the
operation of the heater 117. In this connection, the heater 117
adjusts the temperature of the dielectric window 103 in a range
from the room temperature to 100.degree. C.
[0049] FIG. 2 shows, in a longitudinal cross-sectional view, a
magnified image of an upper section of the plasma processing
apparatus according to the present embodiment shown in FIG. 1. In
the configuration of FIG. 2, the infrared radiation temperature
sensor 119 is installed at a position where the magnetic flux
density generated by the magnetic field generating coil 110 is
equal to or less than one tenth (200 Gauss) of the magnetic flux
density in the coil 110.
[0050] Due to the configuration, a metallic mesh 124 to prevent
leakage of the microwave is arranged on the upper surface of the
member configuring the ceiling surface of the cavity resonator 108
and a viewing window 123 as a disk-shaped member to pass the
infrared ray therethrough is disposed above the metallic mesh 124.
In addition, a viewing hole 126 which is disposed above the viewing
window 123 and which extends along an axis in the perpendicular
direction to view the inside thereof by a sensor and a viewing hole
125 which is connected to an upper section of the viewing hole 126
and in which the cross-section along an axis in the perpendicular
direction is reduced are arranged in the member configuring the
cylindrical section of the waveguide 107. Further, above the
viewing hole 125, in order that the infrared radiation temperature
sensor 119 is installed at a position (with respect to the upper
surface of the coil 110) where the magnetic flux density is equal
to or less than one tenth of the magnetic flux density in the coil
110, there is disposed a support stage 127 mounted on the member
configuring the cylindrical section of the waveguide 107.
[0051] The support stage 127 disposed above the member of the
cylindrical section is tightly fixed onto the member by bolts and
screws Above the upper end section of the support stage 127, the
infrared radiation temperature sensor monitor 119 is mounted to be
fixed thereonto. Although not shown, in order that the infrared ray
emitted from the dielectric window 103 below the viewing holes 125
and 126 and the metallic mesh 124 reaches the infrared radiation
temperature sensor 119 through internal spaces of the viewing holes
125 and 126 and the metallic mesh 124, the support stage 127 is
configured not to block the space for the passage of the infrared
ray between the upper opening of the viewing hole 125 and the light
receiving section of the infrared radiation temperature sensor
monitor 119. The viewing window 123 is configured using a 3-mm
thick planar member which includes calcium fluoride (barium
fluoride or germanium is also available) or a material primarily
including calcium fluoride (barium fluoride or germanium).
[0052] In the present embodiment, an additional viewing window 129
is arranged between the infrared radiation temperature sensor 119
and the viewing window 123 In order that fluid is supplied to the
inside or the surface of the viewing window 123 to be retained in a
temperature range from 20.degree. C. to 30.degree. C., that is, in
the range of room temperature, a fluid blow-off outlet 130 is
disposed. The fluid blow-off outlet 130 is connected via piping to
a dry air tank and a pump as a fluid supply, not shown. Dry air in
the tank is supplied via the piping to the fluid blow-off outlet
130.
[0053] As above, the support stage 127 is configured so that the
viewing window 129 and the fluid blow-off outlet 130 are arranged.
The viewing window 129 is configured using the same material in the
same composition as for the viewing window 123. It is desired that
the planar member configuring these windows are substantially equal
also in thickness to each other.
[0054] FIG. 3 is a graph showing an optical characteristic of the
viewing window according to the embodiment shown in FIG. 2.
Specifically, the graph demonstrates an optical characteristic of
the viewing window 123 in a range of infrared wavelength from 8
.mu.m to 14 .mu.m when the viewing window 123 is constructed using
calcium fluoride and has a thickness of 3 mm.
[0055] In the graph, the abscissa represents the infrared
wavelength and the ordinate represents transmittivity and
emissivity. As can be seen from the graph, the wavelength range
from 8 .mu.m to 10 .mu.m is a zone (to be referred to as a
transmission zone hereinbelow) in which the transmittivity is
dominant, and the wavelength range from 10 .mu.m to 14 .mu.m is a
zone (to be referred to as an emission zone hereinbelow) in which
the emissivity is dominant.
[0056] The wavelength range from 8 .mu.m to 14 .mu.m is a range of
wavelengths which can be sensed by the infrared radiation
temperature sensor 119. In general, an infrared radiation
temperature sensor to conduct observation in a temperature range
from the room temperature to 500.degree. C. includes a thermopile
element. The wavelength range from 8 .mu.m to 14 .mu.m corresponds
to the range of wavelengths which can be sensed by the thermopile
element or at least includes the wavelength range for the
thermopile element. As shown in the graph, the infrared ray sensed
by the temperature sensor 119 including the thermopile element,
specifically, the radiance thereof is, for the wavelength range
from 8 .mu.m to 10 .mu.m, the radiance from the dielectric window
121 which passes through the viewing window 123 and is, for the
wavelength range from 10 .mu.m to 14, the radiance from the
dielectric window 123.
[0057] FIG. 4 is a graph showing a change in the radiance of
infrared rays of a particular body for each wavelength. In the
graph, radiance (to be referred to as spectroscopic radiance
hereinbelow) for each wavelength is represented in the ordinate
with respect to the change in the infrared wavelength represented
in the abscissa for a body at 100.degree. C. and a body at
60.degree. C.
[0058] In the present embodiment, when the dielectric window 103 is
at 100.degree. C., the temperature of the viewing window 123 goes
up to 60.degree. C. or more. In the graph, the change in the
spectroscopic radiance of the infrared ray passing through the
viewing window 123 when the dielectric window 103 is at 100.degree.
C. is indicated by a solid line 402. The change in the
spectroscopic radiance of the infrared ray radiated from the
viewing window 123 when the dielectric window 103 is at 60.degree.
C. is indicated by a solid line 404. When the viewing window 129
disposed at a separate position thereabove is absent, an
integration value 401 obtained by integrating the spectroscopic
radiance of the 100.degree. C. body for wavelength from 8 .mu.m to
10 .mu.m indicates the radiance of the infrared ray from the
dielectric window 103 which passes through the viewing window 123
and which is detected by the temperature sensor 119. An integration
value 403 obtained by integrating the spectroscopic radiance of the
60.degree. C. body for wavelength from 10 .mu.m to 14 .mu.m
indicates the radiance the infrared ray which is emitted from the
viewing window 123 and which is detected by the temperature sensor
119.
[0059] FIG. 5 is a graph showing the radiance detected by the
infrared temperature sensor 119 when there does not exist the
additional viewing window according to the embodiment shown in FIG.
2. The graph shows two kinds of radiance values, i.e., the value of
radiance of the infrared ray which is emitted from the dielectric
window 103 and which passes through the viewing window 123 and the
value of radiance of the infrared ray which is emitted from the
viewing window 123 and which is sensed by the temperature sensor
119.
[0060] In the present embodiment, as can be seen from the graph,
the radiance of the infrared ray which is emitted from the
dielectric window 103 and which passes through the viewing window
123 is similar in the value to the radiance of the infrared ray
emitted from the viewing window 123 to an extent in which they are
assumed to be substantially equal thereto. This indicates that 50
percent of the radiance sensed by the temperature sensor 119 is
resulted from the radiation of infrared ray received from the
viewing window 123. Further, when the radiance of infrared ray is
detected to determine the temperature on the surface of the
dielectric window 103 with the viewing window 123 interposed as
above, the magnitude and precision of the value are considerably
influenced by the viewing window 123.
[0061] FIG. 6 is a graph showing an optical characteristic of an
additional viewing window according to the embodiment shown in FIG.
2. In the graph, the spectroscopic radiance is represented along
the ordinate when a particular body, a blackbody in this example,
is at 100.degree. C. and 60.degree. C.
[0062] Assume that the viewing window 129 is disposed in the
configuration. Since the viewing window 129 is disposed apart from
the viewing window 123 thereabove the value of heat imparted from
the viewing window 123 or via the support stage 127 is quite small
to be regarded as zero or as substantially zero. It is hence
possible to assume that there exists no heat source to heat the
viewing window 123.
[0063] In the present embodiment, the viewing window 129 is in
contact with the dry air supplied as above in a clean room the
temperature of which is appropriately adjusted in a building in
which the plasma processing apparatus is installed, and is set to
the room temperature, specifically, 20.degree. C. In the graph, the
change in the spectroscopic radiance of the infrared ray passing
through the viewing window 123 when the dielectric window 103 is at
100.degree. C. is indicated by a solid line 602. The change in the
spectroscopic radiance of the infrared ray radiated from the
viewing window 129 when the viewing window 129 is at 20.degree. C.
is indicated by a solid line 604. In this graph as in the graph
shown in FIG. 4, an integration value 601 obtained by integrating,
for a wavelength range from 8 .mu.m to 10 .mu.m, the value of the
spectroscopic radiance, indicated by the solid line 602 in this
graph, of the infrared ray which passes through the viewing window
129 when the dielectric window 103 is at 100.degree. C. indicates
the radiance of the infrared ray from the dielectric window 103
which passes through the viewing window 129 and which is detected
by the temperature sensor 119 An integration value 603 obtained by
integrating, for a wavelength range from 10 .mu.m to 14 .mu.m, the
spectroscopic radiance of the infrared ray emitted from the
20.degree. C. viewing window 129 indicates the radiance of the
infrared ray which is emitted from the viewing window 129 and which
is detected by the temperature sensor 119
[0064] FIG. 7 shows the radiance of the infrared ray detected by
the infrared temperature sensor 119 when an additional viewing
window is present. Specifically, FIG. 7 is a graph showing the
radiance detected by the temperature sensor 191 when the additional
viewing window according to the embodiment shown in FIG. 2 is
disposed.
[0065] The graph of FIG. 7 shows two kinds of radiance values, that
is, the value of radiance of the infrared ray which is emitted from
the dielectric window 103 and which passes through the viewing
window 129 and the value of radiance of the infrared ray which is
emitted from the viewing window 129 and which is sensed by the
temperature sensor 119. The value of radiance of the infrared ray
emitted from the viewing window 129 is about 60 percent of the
value of radiance of the infrared ray which is emitted from the
dielectric window 103 and which passes through the viewing window
129. This indicates that the influence from the viewing window 129
is less than that from the viewing window 123.
[0066] FIG. 8 is a graph showing magnitude of a change of the
radiance with respect to a change of temperature of viewing windows
123 and 129 according to the embodiment shown in FIG. 2. As can be
seen from the graph, the quantity of change in the radiance of
viewing window 129 is about one tenth that of change in the
radiance of the viewing window 123. This is because when the
dielectric window 103 is heated from 20.degree. C. up to
100.degree. C., the viewing window 123 changes in temperature from
20.degree. C. to 60.degree. C., but the viewing window 129 changes
in a temperature range from 20.degree. C. to 30.degree. C. in a
more stable state.
[0067] On the other hand, when the viewing window 129 of the
present embodiment is disposed, the influence upon the precision in
the sensing operation of the temperature sensor 119 from the member
of the viewing window 129 can be reduced as compared with when only
the viewing window 123 is disposed. Also, when the temperature of
the viewing window 129 is stabilized, the change in the radiance
from the viewing window 129 is lowered. Hence, it is possible to
further increase the sensing precision. That is, when the variation
in the temperature of the viewing window 129 or the variation in
the radiance due to the variation in the temperature is fully small
or is substantially negligible in magnitude when compared with the
variation in the radiance from the dielectric window 103, it is
possible to correct the output and the detected value and data from
the temperature sensor 119 by use of the temperature from the
viewing window 129 or the value of the radiance obtained using the
temperature.
[0068] FIG. 9 is a graph showing a method of correcting, by use of
the radiance of the viewing window, the output or the detection
value of the infrared temperature sensor 119 according to the
embodiment shown in FIG. 2. In this example, for the correction of
the detection value, there are employed the radiance value in a
range of the infrared wavelength from 8 .mu.m to 14 .mu.m for the
temperature ranging from 20.degree. C. to 100.degree. C. of the
viewing window 129 and the radiance value in a range of the
infrared wavelength from 8 .mu.m to 10 .mu.m for the temperature
ranging from 20.degree. C. to 100.degree. C. of the viewing window
129, specifically, the integration values obtained by integrating
the spectroscopic radiance values respectively in these wavelength
ranges.
[0069] These values are beforehand recorded or stored as data of
conversion values, in the warm-wind heater controller 118 or in a
storage such as a memory or a hard disk which are externally
installed and which are communicably connected to the heater
controller 118. Assume that at reception of infrared rays via the
viewing windows 123 and 129, the infrared temperature sensor 119
resultantly indicates 55.degree. C. as the detection value of
temperature. For the radiance from the viewing window 129 in a
predetermined temperature range, the arithmetic unit such as a CPU
device or the like in the heater controller 118 refers to data in
the storage to obtain 32.2 W/sr/m.sup.2 as the radiance as shown in
FIG. 7. Hence, by subtracting the radiance 32.2 W/sr/m.sup.2 of the
viewing window 129 from the radiance 81.6 W/sr/m.sup.2 described
above, to thereby detect or calculate the radiance of the infrared
ray received through the viewing window 129 as 49.4
W/sr/m.sup.2.
[0070] For 49.4 W/sr/m.sup.2, the arithmetic unit calculates the
temperature corresponding to the integration value of the radiance
in the wavelength range from 8 .mu.m to 14 .mu.m based on the
beforehand stored data, to obtain the temperature as 98.degree. C.
As a result, the heater controller 118 detects that the temperature
of dielectric window 103 is 98.degree. C. As above, by correcting
the detection value of the infrared temperature sensor 119, the
influence from the viewing window 129 is reduced, to detect the
temperature with high precision. In addition, based on the
temperature detection with high precision, it is possible that the
temperature of the inner walls of the processing chamber of the
plasma processing apparatus is appropriately adjusted, to
appropriately conduct processing in the plasma processing
apparatus. As a result, it is possible to obtain a desired contour
of wiring structure on the upper surface of the wafer.
[0071] It should be further understood by those skilled in the art
that although the foregoing description has been made on
embodiments of the invention, the invention is not limited thereto
and various changes and modifications may be made without departing
from the spirit of the invention and the scope of the appended
claims.
* * * * *