U.S. patent application number 13/432623 was filed with the patent office on 2012-10-04 for plasma processing apparatus.
This patent application is currently assigned to TOKYO ELECTRON LIMITED. Invention is credited to Chishio KOSHIMIZU, Jun YAMAWAKU.
Application Number | 20120247954 13/432623 |
Document ID | / |
Family ID | 46925811 |
Filed Date | 2012-10-04 |
United States Patent
Application |
20120247954 |
Kind Code |
A1 |
YAMAWAKU; Jun ; et
al. |
October 4, 2012 |
PLASMA PROCESSING APPARATUS
Abstract
Disclosed is a capacitively-coupled plasma etching apparatus, in
which a focus ring is provided surrounding a substrate placing area
of a placing table for adjusting a state of plasma. A ring type
insulating member is installed along the focus ring between the top
surface of the placing table and the bottom surface of the focus
ring, and a heat transfer member is installed between the top
surface of the placing table and the bottom surface of the focus
ring to be closely attached to the top surface and the bottom
surface at a position adjacent to the insulating member in a
diameter direction of a wafer. During the plasma processing, the
heat in the focus ring is transferred to the placing table through
the heat transfer member to be cooled down and the amount of
sediment attached to the rear surface of the wafer can be
reduced.
Inventors: |
YAMAWAKU; Jun; (Nirasaki
City, JP) ; KOSHIMIZU; Chishio; (Nirasaki City,
JP) |
Assignee: |
TOKYO ELECTRON LIMITED
Tokyo
JP
|
Family ID: |
46925811 |
Appl. No.: |
13/432623 |
Filed: |
March 28, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61477636 |
Apr 21, 2011 |
|
|
|
Current U.S.
Class: |
204/298.31 |
Current CPC
Class: |
H01J 37/32715 20130101;
H01J 37/32642 20130101; H01J 37/32091 20130101 |
Class at
Publication: |
204/298.31 |
International
Class: |
C23F 4/00 20060101
C23F004/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2011 |
JP |
2011-072677 |
Claims
1. A plasma processing apparatus that processes a substrate to be
processed using plasma, the apparatus comprising: a vacuum chamber
including a lower electrode and an upper electrode configured to
generate the plasma by introducing a processing gas and applying a
high-frequency power between the lower electrode and an upper
electrode, thereby processing the substrate using the plasma; a
placing table provided in the vacuum chamber serving as the lower
electrode and configured to receive a substrate on a substrate
placing area; a ring member installed on the placing table
surrounding the substrate placing area and configured to adjust a
state of the plasma generated between the lower electrode and the
upper electrode; an insulating member installed along the ring
member between a top surface of the placing table and a bottom
surface of the ring member in a concentric pattern with a center of
the substrate on the placing table and configured to adjust a
potential difference between the ring member and the substrate
thereby injecting ions of the plasma into a rear surface of the
substrate; and a heat transfer member closely attached to each of
the top surface of the placing table and the bottom surface of the
ring member along the ring member between the top surface of the
placing table and the bottom surface of the ring member at a
position adjacent to the insulating member in a diameter direction
of the substrate.
2. The plasma processing apparatus of claim 1, wherein the top
surface of the insulating member contacts the ring member.
3. The plasma processing apparatus of claim 1, wherein the
insulating member is installed at both sides of the inside and the
outside of the diameter direction of the substrate with respect to
the heat transfer member.
4. A plasma processing apparatus that processes a substrate to be
processed using plasma, the apparatus comprising: a vacuum chamber
including a lower electrode and an upper electrode configured to
generate the plasma by introducing a processing gas and applying a
high-frequency power between the electrodes, thereby processing the
substrate using the plasma; a placing table provided in the vacuum
chamber serving as the lower electrode and configured to receive a
substrate on a substrate placing area; a ring member installed on
the placing table surrounding the substrate placing area and
configured to adjust a state of plasma generated between the lower
electrode and the upper electrode; an insulating member installed
along the ring member between a top surface of the placing table
and a bottom surface of the ring member in a concentric pattern
with a center of the substrate on the placing table and configured
to adjust a potential difference between the ring member and the
substrate thereby injecting ions of the plasma into a rear surface
of the substrate; a plurality of lower heat transfer members
closely attached to each of the insulating member and the placing
table between a top surface of the insulating member and a top
surface of the placing table in a concentric pattern with a center
of the substrate on the placing table along the ring member and
spaced apart from one another in a diameter direction of the ring
member; and a plurality of upper heat transfer members closely
attached to each of the insulating member and the ring member
between a bottom surface of the insulating member and a bottom
surface of the ring member in the concentric pattern with the
center of the substrate on the placing table along the ring member
and spaced apart from one another in the diameter direction of the
ring member.
5. The plasma processing apparatus of claim 4, wherein at least one
side of the upper heat transfer member and the lower heat transfer
member is notched so that a space between the heat transfer members
adjacent to each other in the diameter direction of the ring member
is allowed to communicate with atmosphere in the vacuum
chamber.
6. A plasma processing apparatus that processes a substrate to be
processed using plasma, the apparatus comprising: a vacuum chamber
including a lower electrode and an upper electrode configured to
generate the plasma by introducing a processing gas and applying a
high-frequency power between the lower electrode and an upper
electrode, thereby processing the substrate using the plasma; a
placing table provided in the vacuum chamber serving as the lower
electrode and configured to receive a substrate on a substrate
placing area; a ring member installed on the placing table
surrounding the substrate placing area and configured to adjust a
state of plasma generated between the lower electrode and the upper
electrode; an insulating member installed along the ring member
between a top surface of the placing table and a bottom surface of
the ring member in a concentric pattern with a center of the
substrate on the placing table and configured to adjust a potential
difference between the ring member and the substrate thereby
injecting ions of the plasma into a rear surface of the substrate;
and a heat transfer member closely attached to each of the sides of
the ring member, the insulating member, and the placing table
between those sides along the ring member.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and claims priority from
Japanese Patent Application No. 2011-072677, filed on Mar. 29,
2011, with the Japanese Patent Office, the disclosure of which is
incorporated herein in its entirety by reference. Also, this
application claims the benefit of U.S. Provisional Application No.
61/477,636 filed on Apr. 21, 2011, with the United States Patent
and Trademark Office, the disclosure of which is incorporated
herein in its entirety by reference.
TECHNICAL FIELD
[0002] The present disclosure relates to a technology that performs
a plasma processing on a substrate such as a semiconductor wafer or
a glass substrate for a flat panel display (FPD).
BACKGROUND
[0003] In a manufacturing process of a semiconductor substrate such
as a semiconductor wafer or a glass substrate for an FPD, a
predetermined plasma processing such as an etching process or a
film forming process is performed with respect to a substrate. In a
plasma processing apparatus that performs the process, a substrate
is placed on a placing table in a vacuum chamber and processing gas
becomes a plasma in an upper space of the placing table, such that
the plasma processing is performed with respect to the substrate.
As shown in FIG. 15A, an annular focus ring 12 made of a conductive
member such as, for example, silicon is installed around a
substrate, for example, a semiconductor wafer W (`wafer W`) placed
on a placing table 11 in order to perform a uniform processing by
keeping plasma on wafer W and alleviating discontinuity of a bias
potential in the plane of wafer W.
[0004] A temperature control fluid path (not shown) is installed in
placing table 11, and plasma processing is performed in a state
where wafer W is adjusted to a predetermined temperature by a
balance of heat absorption from plasma and heat dissipation to
placing table 11. Meanwhile, since focus ring 12 is exposed to
plasma while focus ring 12 is thermally excited, focus ring 12 has
a higher temperature than wafer W. In the mean time, since radical
species or a reaction by-product is attached to a low-temperature
portion to form a polymer (sediment) and wafer W has a lower
temperature than focus ring 12 as described above, a polymer 13 is
easily formed at an edge portion of wafer W. While polymer 13
formed at the edge portion of wafer W is removed by a plasma ion
sputtering, polymer 13 formed at the rear surface of wafer W may
not be removed by the same sputtering process because the plasma is
not irradiated at the rear surface of wafer W.
[0005] As a technique of removing the polymer, Japanese Patent
Application Laid-Open No. 2005-277369 and Japanese Patent
Application Laid-Open No. 2007-250967 propose a configuration in
which a potential difference between wafer W and a focus ring is
controlled by inserting an insulating material below the focus
ring. In this configuration, as shown in FIG. 15B, the potential
difference between wafer W and focus ring 12 is adjusted by
insulating material 14, the plasma ions are guided to the rear
surface of wafer W by changing trajectories of the incident plasma
ions, thereby removing polymer 13 by sputtering.
[0006] According to this configuration, although the polymer
attached to the rear surface of wafer W can be removed, attachment
of the polymer to the periphery of the rear surface of wafer W
itself is not suppressed since the temperature of focus ring 12
cannot be controlled. Also, there is a possibility that polymer
attached to wafer W may not be completely removed depending on
conditions. In this case, the polymer is peeled off by, for
example, a batch cleaning as a post process, but the polymer may be
attached to the surface of a device through a cleaning liquid,
which may cause a defect. While wafer W of a single lot is
processed, the temperature of focus ring 12 is increased with
plasma being irradiated and the trajectories of the plasma ions
that detours into the rear surface of wafer W are changed by the
change in temperature, such that the polymer may not be stably
removed.
[0007] Japanese Patent Application Laid-Open No. 2007-258500
proposes a technology in which attachment of the sediment to a
bevel portion of wafer W is suppressed by laminating a first heat
transfer medium, a dielectric ring, a second heat transfer medium
and an insulating member vertically between the focus ring and an
electrode block. In this configuration, voltage applied to a sheath
formed on a front surface of the focus ring is suppressed by the
dielectric ring to suppress heat absorption to the focus ring and
heat is transferred to the electrode block from the focus ring
using the first and second heat transfer media. Therefore, the
temperature of the focus ring is made to be lower than that of
wafer W to suppress the attachment of the sediment to the bevel
portion of wafer W.
[0008] Herein, when an insulator and a thermal conductor are formed
in a laminated structure, air bubbles are easily mixed into a
contact surface between the thermal conductor and the insulator.
However, a contact state between the insulator and the focus ring
is changed by the presence of the air bubbles, such that it is
difficult to uniformly transfer heat in the plane of the focus
ring. Since the removal of the polymer attached to the rear surface
of the wafer by sputtering is implemented by the potential
difference between the edge portion of wafer W and the focus ring,
subtle impedance control by the insulator installed under the focus
ring is required. However, the contact state between the insulator
and focus ring is changed by the presence of the air bubbles
between the insulator and the focus ring, such that a bad influence
may be exerted on the impedance control as well. Moreover, when the
insulator and the thermal conductor are formed in the laminated
structure, the thermal conductor may be deformed or the air bubbles
may be mixed into a portion between the thermal conductor and the
insulator, such that the periphery of the focus ring is easily
inclined downward and the control of height of the focus ring
becomes difficult. As a result, the control of a plasma state of
the periphery of wafer W becomes unstable.
SUMMARY
[0009] An exemplary embodiment of the present disclosure provides a
plasma processing apparatus that processes a substrate to be
processed using plasma, the apparatus including: a vacuum chamber
including a lower electrode and an upper electrode configured to
generate the plasma by introducing a processing gas and applying a
high-frequency power between the lower electrode and an upper
electrode, thereby processing the substrate using the plasma; a
placing table provided in the vacuum chamber serving as the lower
electrode and configured to receive a substrate on a substrate
placing area; a ring member installed on the placing table
surrounding the substrate placing area and configured to adjust a
state of the plasma generated between the lower electrode and the
upper electrode; an insulating member installed along the ring
member between a top surface of the placing table and a bottom
surface of the ring member in a concentric pattern with a center of
the substrate on the placing table and configured to adjust a
potential difference between the ring member and the substrate
thereby injecting ions of plasma into a rear surface of the
substrate; and a heat transfer member closely attached to each of
the top surface of the placing tale and the bottom surface of the
ring member along the ring member between the top surface of the
placing table and the bottom surface of the ring member at a
position adjacent to the insulating member in a diameter direction
of the substrate.
[0010] The foregoing summary is illustrative only and is not
intended to be in any way limiting. In addition to the illustrative
aspects, embodiments, and features described above, further
aspects, embodiments, and features will become apparent by
reference to the drawings and the following detailed
description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a longitudinal side view illustrating a plasma
etching apparatus according to a first exemplary embodiment of the
present disclosure.
[0012] FIG. 2 is a longitudinal cross-sectional view illustrating a
part of a placing table installed in the plasma etching
apparatus.
[0013] FIG. 3 is a plan view and a longitudinal cross-sectional
view of the placing table.
[0014] FIG. 4 is a longitudinal cross-sectional view for
illustrating an operation of the present disclosure.
[0015] FIG. 5 is a longitudinal cross-sectional view illustrating
another example of the first exemplary embodiment of the present
disclosure.
[0016] FIG. 6 is a longitudinal cross-sectional view illustrating a
plasma etching apparatus according to a second exemplary embodiment
of the present disclosure.
[0017] FIG. 7 is a plan view illustrating a placing table installed
in the plasma etching apparatus of FIG. 6.
[0018] FIG. 8 is a plan view illustrating another example of the
placing table of the second exemplary embodiment of the present
disclosure.
[0019] FIG. 9 is a plan view illustrating yet another example of
the placing table of the second exemplary embodiment of the present
disclosure.
[0020] FIGS. 10A, 10B and 10C each illustrates yet another example
of the placing table of the second exemplary embodiment of the
present disclosure in a plan view and a longitudinal
cross-sectional view.
[0021] FIGS. 11A and 11B each illustrates a plasma etching
apparatus according to a third exemplary embodiment of the present
disclosure in a plan view and a partial perspective view.
[0022] FIGS. 12A and 12B each illustrates another example of the
placing table of the plasma etching apparatus of the present
disclosure in a longitudinal cross-sectional view.
[0023] FIG. 13 is a longitudinal cross-sectional view illustrating
yet another example of the placing table of the plasma etching
apparatus of the present disclosure.
[0024] FIG. 14 is a feature diagram illustrating an exemplary
embodiment performed to verify an effect of the present
disclosure.
[0025] FIGS. 15A and 15B each illustrates a placing table in the
related art in a longitudinal cross-sectional view.
DETAILED DESCRIPTION
[0026] In the following detailed description, reference is made to
the accompanying drawing, which form a part hereof. The
illustrative embodiments described in the detailed description,
drawing, and claims are not meant to be limiting. Other embodiments
may be utilized, and other changes may be made, without departing
from the spirit or scope of the subject matter presented here.
[0027] The present disclosure has been made in an effort to provide
a technology that can suppress the amount of sediment attached to a
rear surface of a substrate by controlling the temperature of a
ring member.
[0028] An exemplary embodiment of the present disclosure provides a
plasma processing apparatus that processes a substrate to be
processed using plasma, the apparatus including: a vacuum chamber
including a lower electrode and an upper electrode configured to
generate the plasma by introducing a processing gas and applying a
high-frequency power between the lower electrode and an upper
electrode, thereby processing the substrate using the plasma; a
placing table provided in the vacuum chamber serving as the lower
electrode and configured to receive a substrate on a substrate
placing area; a ring member installed on the placing table
surrounding the substrate placing area and configured to adjust a
state of the plasma generated between the lower electrode and the
upper electrode; an insulating member installed along the ring
member between a top surface of the placing table and a bottom
surface of the ring member in a concentric pattern with a center of
the substrate on the placing table and configured to adjust a
potential difference between the ring member and the substrate
thereby injecting ions of the plasma into a rear surface of the
substrate; and a heat transfer member closely attached to each of
the top surface of the placing table and the bottom surface of the
ring member along the ring member between the top surface of the
placing table and the bottom surface of the ring member at a
position adjacent to the insulating member in a diameter direction
of the substrate.
[0029] In the plasma processing apparatus, the top surface of the
insulating member contacts the ring member.
[0030] The insulating member is installed at both sides of the
inside and the outside of the diameter direction of the substrate
with respect to the heat transfer member.
[0031] A yet another exemplary embodiment of the present disclosure
provides a plasma processing apparatus that processes a substrate
to be processed using plasma, the apparatus including: a vacuum
chamber including a lower electrode and an upper electrode
configured to generate the plasma by introducing a processing gas
and applying a high-frequency power between the electrodes, thereby
processing the substrate using the plasma; a placing table provided
in the vacuum chamber serving as the lower electrode and configured
to receive a substrate on a substrate placing area; a ring member
installed on the placing table surrounding the substrate placing
area and configured to adjust a state of plasma generated between
the lower electrode and the upper electrode; an insulating member
installed along the ring member between a top surface of the
placing table and a bottom surface of the ring member in a
concentric pattern with a center of the substrate on the placing
table and configured to adjust a potential difference between the
ring member and the substrate thereby injecting ions of the plasma
into a rear surface of the substrate; a plurality of lower heat
transfer members closely attached to each of the insulating member
and the placing table between a top surface of the insulating
member and a top surface of the placing table in a concentric
pattern with a center of the substrate on the placing table along
the ring member and spaced apart from one another in a diameter
direction of the ring member; and a plurality of upper heat
transfer members closely attached to each of the insulating member
and the ring member between a bottom surface of the insulating
member and a bottom surface of the ring member in the concentric
pattern with the center of the substrate on the placing table along
the ring member and spaced apart from one another in the diameter
direction of the ring member.
[0032] In the plasma processing apparatus, at least one side of the
upper heat transfer member and the lower heat transfer member is
notched so that a space between the heat transfer members adjacent
to each other in the diameter direction of the ring member is
allowed to communicate with atmosphere within the vacuum
chamber.
[0033] Another exemplary embodiment of the present disclosure
provides a plasma processing apparatus that processes a substrate
to be processed using plasma, the apparatus comprising: a vacuum
chamber including a lower electrode and an upper electrode
configured to generate the plasma by introducing a processing gas
and applying a high-frequency power between the lower electrode and
an upper electrode, thereby processing the substrate using the
plasma; a placing table provided in the vacuum chamber serving as
the lower electrode and configured to receive a substrate on a
substrate placing area; a ring member installed on the placing
table surrounding the substrate placing area and configured to
adjust a state of plasma generated between the lower electrode and
the upper electrode; an insulating member installed along the ring
member between a top surface of the placing table and a bottom
surface of the ring member in a concentric pattern with a center of
the substrate on the placing table and configured to adjust a
potential difference between the ring member and the substrate
thereby injecting ions of the plasma into a rear surface of the
substrate; and a heat transfer member closely attached to each of
the sides of the ring member, the insulating member, and the
placing table between those sides along the ring member.
[0034] According to exemplary embodiments of the present
disclosure, since a heat transfer member and insulating member are
installed between a ring member and a placing table, an increase in
temperature of the ring member at the time of irradiating plasma
can be suppressed and attachment of sediment to a substrate can be
suppressed. Even though the sediment are attached to the substrate,
confusion of trajectories of plasma ions that detour into a rear
surface of the substrate due to a change in temperature of the ring
member is suppressed, and as a result, the sediment attached to the
rear surface of the substrate can be stably removed by sputtering
and the amount of the attached sediment can be reduced.
[0035] Hereinafter, a capacitively-coupled plasma etching apparatus
according to an exemplary embodiment of the present disclosure will
be described. FIG. 1 is a longitudinal cross-sectional view
illustrating a plasma etching apparatus 2 which includes an
airtight processing chamber (vacuum chamber) 20 made of, for
example, aluminum for performing a plasma processing for wafer W
placed therein. A placing table 3 is installed at the center of the
bottom of processing chamber 20 and configured such that the
periphery of the top of a cylinder is notched across the entirety
of a circumference thereof and a step portion 31 is formed in a
shape in which a part other than the periphery protrudes
cylindrically on the top. The protruding portion forms a substrate
placing area 32 (hereinafter, referred to as a `placing area`)
where wafer W serving as a substrate is placed, and step portion 31
surrounding placing area 32 corresponds to a placing area of a ring
member to be described below.
[0036] An electrostatic chuck 33 formed by placing a chuck
electrode 33a on an insulating layer is installed on the top of
placing area 32 and wafer W is placed on electrostatic chuck 33
with the periphery thereof being protruded. Chuck electrode 33a is
electrically connected with a DC power supply 34 installed outside
processing chamber 20 through a switch 35. A plurality of discharge
openings (not shown) are formed in electrostatic chuck 33, and heat
medium gas, for example, He gas is supplied to a minute space
between corresponding electrostatic chuck 33 and wafer W from a gas
supplying unit (not shown). An elevation pin (not shown) is
installed in placing table 3 and configured to transfer wafer W
between an external transportation arm (not shown) and
electrostatic chuck 33.
[0037] A refrigerant circulation chamber 36 is installed in placing
table 3 and refrigerants are circulated and supplied from a
refrigerant supplying unit 37 installed outside placing table 3.
That is, the refrigerants supplied to refrigerant circulation
chamber 36 from refrigerant supplying unit 37 through a supply path
36a are discharged outside placing table 3 through a discharge path
36b and cooled down to a predetermined temperature by a chiller in
refrigerant supplying unit 37, and thereafter, supplied to
refrigerant circulation chamber 36 through supply path 36a again.
Placing table 3 also serves as a lower electrode and is connected
to a high-frequency power supply unit 38 through a matching device
39. High-frequency power supply unit 38 is a bias power supply for
applying a bias to the lower electrode for injecting ions within
plasma.
[0038] Meanwhile, a shower head 4 is installed on a ceiling of
processing chamber 20 through insulating member 21 to face placing
area 32 and connected to a gas supply system 41 through a supply
path 42. Shower head 4 is configured such that a buffer chamber 43
is formed therein, a plurality of discharge openings 44 are formed
on the bottom thereof, and processing gas supplied to buffer
chamber 43 from gas supply system 41 is discharged toward placing
area 32 side through discharge openings 44. Shower head 4 also
serves as an upper electrode and is connected to a plasma
generating high-frequency power supply unit 46 through a matching
device 45.
[0039] An exhaust port 22 is installed on the bottom of processing
chamber 20 and a vacuum pump 25 as a vacuum exhaust mechanism is
connected to exhaust port 22 through an exhaust path 24 in which a
valve V and a pressure adjusting unit 23 are installed. A
transportation opening 27 of wafer W which is opened/closed by a
shutter 26 is provided on the side of processing chamber 20.
[0040] A focusing ring 5, made of a conductive material such as,
for example, silicon, is installed on a bottom surface (step
surface) of step portion 31 formed on the periphery of the top
surface of placing table 3 through insulating member 6 and heat
transfer member 7 as shown in FIG. 2 and FIG. 3. Focus ring 5 is
installed on placing table 3 to surround placing area 32 and
constitutes a ring member for adjusting a state of plasma. The
inner periphery of focus ring 5 is notched across the entirety of a
circumference thereof to form a step portion 51 and the periphery
that protrudes from placement area 32 of wafer W enters into step
portion 51 of focus ring 5. The shapes of placing area 32 and focus
ring 5 are set so that a small gap is formed between an outer
peripheral surface 32a of placing area 32 and an inner peripheral
surface 52 of a lower side of step portion 51 of focus ring 5.
Therefore, when wafer W is placed in placing area 32, focus ring 5
is installed to surround the side from the rear surface of the
periphery of wafer W.
[0041] Insulating member 6 and heat transfer member 7 are installed
to be lined up in a diameter direction of wafer W on placing table
3, between step portion 31 of placing table 3 and the bottom
surface of focus ring 5. As shown in FIG. 2 and FIG. 3, insulating
member 6 is installed in a concentric pattern with respect to the
center of wafer W on placing table 3 along focus ring 5 between the
top surface of placing table 3 and the bottom surface of focus ring
5, and serves to adjust a potential difference between focus ring 5
and wafer W to inject ions within plasma into the rear surface of
wafer W. In this example, insulating member 6 is formed in a ring
type and contacts the bottom surface of focus ring 5, and is
installed to fill the gap between inner peripheral surface 52 of
the lower side of step portion 51 of focus ring 51 and outer
peripheral surface 32a of placing area 32 of placing table 3.
Insulating member 6 may be made of, for example, silicon dioxide
(SiO.sub.2) or ceramics, and aluminum nitride (AlN), sapphire as
well as quartz.
[0042] Heat transfer member 7 is positioned adjacent to insulating
member 6 in the diameter direction of wafer W on placing table 3,
and installed along focus ring 5 between the top surface of placing
table 3 and the bottom surface of focus ring 5 in close contact
with the top and the bottom surfaces. In this example, heat
transfer member 7 is installed outside the diameter direction of
wafer W with respect to insulating member 6. Heat transfer member 7
is composed of a high-molecular silicon gel filled with alumina as
a material which has high thermal conductivity in this example and
may acquire a certain degree of thermal conductivity in which an
effect of suppressing attachment of radical species or reaction
by-product to wafer W becomes remarkable by cooling focus ring 5.
Heat transfer member 7 may be composed of a material having a high
thermal conductivity coefficient such as a silicon based resin, a
carbon based resin, or a fluorine based resin as well as the
high-molecular silicon gel.
[0043] In this example, the height of the top surface of insulating
member 6 is configured to coincide with the height of the top of
heat transfer member 7, and focus ring 5 is placed on insulating
member 6 and heat transfer member 7, such that focus ring 5 is
installed on step portion 31 of placing table 3 while the height is
restrained by insulating member 6 which is made of quartz. In this
case, since the high-molecular silicon gel filled with alumina
formed by an elastic body having adhesiveness is used as heat
transfer member 7, adherence between heat transfer member 7 and
focus ring 5 as well as between heat transfer member 7 and step
portion 31 of placing table 3 is ensured by the adhesiveness
thereof. When focus ring 5 is installed on insulating member 6 and
heat transfer member 7, the potential difference between wafer W
and focus ring 5 is adjusted to a predetermined range, and a
vertical size (height L1) or a horizontal size (widths L2 and L2)
are respectively set so that focus ring 5 is not inclined
horizontally (in the diameter direction of wafer W on placing table
3).
[0044] Plasma etching apparatus 2 is controlled by a control unit
100 constituted with, for example, a computer and has a program, a
memory, and a CPU. The program includes commands (each step) used
to perform a predetermined etching process by transmitting a
control signal from control unit 10 to each unit of plasma etching
apparatus 2. The program is stored in a storage unit serving as a
computer storage medium such as, for example, a flexible disk, a
compact disk, a hard disk, and a magneto-optic (MO) disk, and
installed in control unit 100.
[0045] Herein, the program includes programs for controlling a
switch 35 of electrostatic chuck 33, ON/OFF of high-frequency power
supply units 38 and 46, supply start and supply stop of the
processing gas by gas supplying system 41, and opening/closing of
valve V of vacuum pump 25, and is configured to control each unit
according to a process recipe prestored in the memory of control
unit 100.
[0046] Continuously, an operation of plasma etching apparatus 2
will be described. First, shutter 26 is opened and wafer W is
carried into processing chamber 20 from a vacuum transportation
chamber (not shown) through transportation opening 27 using a
transportation arm (not shown). Wafer W is then transferred onto
electrostatic chuck 33 to be adsorbed and held by cooperation
between an elevation pin (not shown) and the transportation arm.
After shutter 26 is closed, a predetermined processing gas (e.g.,
an etching gas) is supplied from gas supply system 41 through
shower head 4 while the inside of processing chamber 20 is
vacuum-exhausted by vacuum pump 25.
[0047] Meanwhile, a high-frequency power for generating plasma is
supplied to shower head 4 from high-frequency power supply unit 46
and bias high-frequency power is supplied to placing table 3 from
high-frequency power supply unit 38 to generate plasma, and an
etching process is performed for wafer W with the plasma.
[0048] Since wafer W on placing table 3 is exposed to plasma during
plasma processing, wafer W absorbs heat from the plasma. However,
since placing table 3 is cooled down by circulation of the
refrigerants and maintained to a preset reference temperature as
described above, heat of wafer W is dissipated to placing table 3
through He gas. Accordingly, wafer W is maintained to a
predetermined temperature by a heat balance between the operations
of heat absorption from plasma and heat dissipation to placing
table 3.
[0049] Focus ring 5 is also exposed to plasma to absorb heat from
plasma. However, since focus ring 5 is installed on placing table 3
through heat transfer member 7 having the high thermal
conductivity, and further, the bottom surface of focus ring 5, the
top surface of heat transfer member 7, the bottom surface of heat
transfer member 7 and the top surface of placing table 3 are
closely attached to each other by the adhesiveness of heat transfer
member 7, respectively, heat of focus ring 5 is rapidly transferred
to placing table 3 through heat transfer member 7 as shown in FIG.
4. Therefore, as apparent from the exemplary embodiment to be
described below, focus ring 5 is cooled down by heat transfer
member 7 and the temperature difference between wafer W and focus
ring 5 on placing table 3 is removed during plasma processing. As a
result, the radical species or reaction by-products are suppressed
from selectively entering into the periphery of the rear surface of
wafer W. As described above, since focus ring 5 is cooled down and
the temperature difference between wafer W and focus ring 5 on
placing table 3 is removed, the effect of impeding the attachment
of the radical species or by-products to wafer W becomes remarkable
during the plasma processing.
[0050] Since the potential of focus ring 5 is adjusted by
insulating member 6 and the potential difference between focus ring
5 and wafer W is adjusted so that the potential of wafer W is lower
than the potential of focus ring 5 (negatively increases), the ions
within plasma are injected into wafer W. As a result, as shown in
FIG. 4, even though the polymer is formed on the rear surface of
wafer W by controlling the trajectories of the ions within plasma
to detour into the rear surface of wafer W, the polymer is removed
by sputtering. Although plasma is irradiated to insulating member 6
as well, O radicals are generated from insulating member 6 made of
quartz by the plasma sputtering. Further, the polymer formed on the
rear surface of wafer W is removed as well by the O radicals.
[0051] After wafer W is etched for a predetermined time, the supply
of the processing gas and the supply of the high-frequency power
from high-frequency power supply units 38, 46 stops, the vacuum
exhaust in processing chamber 20 by vacuum pump 25 stops, and wafer
W is then carried out to the outside of processing chamber 20.
[0052] According to the aforementioned exemplary embodiment, since
insulating member 6 and heat transfer member 7 are installed under
focus ring 5, focus ring 5 is cooled down during plasma processing
to suppress the attachment of the polymer (sediment) onto the
periphery of the rear surface of wafer W. In this case, since heat
transfer member 7 is installed in the concentric pattern with wafer
W on placing table 3, focus ring 5 is substantially uniformly
cooled in a circumferential direction of wafer W. Since the
increase in temperature of focus ring 5 is suppressed and the
temperature is stable, there is no concern that the trajectories of
the ions in plasma which detour into the rear surface of wafer W
will be changed due to the change in temperature of focus ring 5.
As a result, the polymer formed on the rear surface of wafer W can
be stably removed by the sputtering, such that the amount of
polymers attached can be reduced.
[0053] Insulating member 6 and heat transfer member 7 are installed
to be adjacent to each other in the diameter direction of wafer W
on placing table 3, and focus ring 5 is placed on insulating member
6 and heat transfer member 7. In this case, since the height of
focus ring 5 is restrained by insulating member 6 made of quartz,
there is no concern that the height of focus ring 5 will be
changed. Further, confusion of plasma on the periphery of wafer W
is suppressed. Since heat transfer member 7 is not interposed
between insulating member 6 and focus ring 5, there is no concern
that impedance under focus ring 5 will be changed. Further, the
potential of the focus ring during plasma processing is
stabilized.
[0054] As described above, a portion that electrically connects
both sides through insulating member 6 and a portion that thermally
connects both sides through heat transfer member 7 are separately
provided between focus ring 5 and placing table 3. As a result,
since an electrical control by insulating member 6 and a
temperature control by heat transfer member 7 are independently
performed, complexity of the controls can be suppressed. In the
aforementioned exemplary embodiment, since insulating member 6 is
installed to be corresponded to placing area 32 side, insulating
member 6 is positioned near wafer W on placing table 3 and the
removal of the polymer by the O radicals which has been already
described is rapidly performed.
[0055] In the above-mentioned exemplary embodiment, the insulating
member and the heat transfer member may be installed to be adjacent
to each other in the diameter direction of wafer W on placing table
3 between focus ring 5 and placing table 3, and as shown in FIG. 5,
an insulating member 61 may be installed outside the diameter
direction of wafer W with respect to a heat transfer member 71. In
this example, heat transfer member 71 is installed so that an inner
peripheral surface 70 thereof is aligned vertically to inner
peripheral surface 52 of the lower side of step portion 51 of focus
ring 5.
[0056] Continuously, a second exemplary embodiment of the present
disclosure will be described with reference to FIG. 6 and FIG. 7.
In the configuration of the present example in which the insulating
member and the heat transfer member are installed in the concentric
pattern outside placing area 32, a first insulating member 62a and
a second insulating member 62b are installed adjacent to both left
and right sides (both sides in the diameter direction of wafer W on
placing table 3) of a heat transfer member 72, respectively. This
configuration is implemented by forming insulating members 62a, 62b
and sheet-type heat transfer member 72 in an annular pattern,
respectively, and by arranging, on the top of step portion 31 of
placing table 3, first insulating member 62a, heat transfer member
72, and second insulating member 62b to be lined up in sequence
toward the outside from the inside in the diameter direction of
wafer W on placing table 3.
[0057] Even in this example, focus ring 5 is installed with the
height position thereof is restrained by first insulating member
62a and second insulating member 62b made of, for example, quartz.
Since heat transfer member 72 has adhesiveness, focus ring 5 and
heat transfer member 72 as well as insulating member 72 and placing
table 3 are closely attached to each other by the adhesiveness,
respectively.
[0058] Even in this configuration, since insulating members 62a,
62b and heat transfer member 72 are installed horizontally adjacent
to each other between placing table 3 and focus ring 5, focus ring
5 is substantially uniformly cooled down along the circumference
direction thereof and the amount of the polymers attached to the
rear surface of wafer W can be reduced. Further, since insulating
members 62a, 62b are installed at both horizontal sides of heat
transfer member 72, the adhesiveness between heat transfer member
72, focus ring 5 and placing table 3 can be ensured while the
change in height of focus ring 5 is further restrained. The
electrical control of focus ring 5 by insulating members 62a, 62b
and the temperature control of focus ring 5 by heat transfer member
72 may be independently performed.
[0059] Furthermore, since heat transfer member 72 is being
surrounded by insulating members 62a, 62b, it is difficult to
sputter heat transfer member 72 with plasma. As a result, since
consumption or deterioration of heat transfer member 72 can be
suppressed, the temperature control of focus ring 5 may be stably
performed over an extended period of time.
[0060] Continuously, a modified example of the exemplary embodiment
will be described with reference to FIG. 8 to FIGS. 10A, 10B and
10C. In a configuration of FIG. 8 in which an insulating member 63
and a heat transfer member 73 are installed outside placing area 32
in a concentric pattern with corresponding placing area 32, heat
transfer member 73 is installed to be spaced apart from each other
in the circumferential direction of wafer W on placing table 3. In
this case, a cross section taken along line A-A of FIG. 8 is
defined as shown in FIG. 6.
[0061] In this case, as shown in FIG. 9, a plurality of heat
transfer members 74 may be installed in an insulating member 64 to
be spaced apart from each other in the concentric pattern with
placing area 32. In this case, a cross section taken along line B-B
of FIG. 9 is defined as shown in FIG. 6.
[0062] In these configurations of FIG. 8 and FIG. 9, notches are
formed to be spaced apart from one another in insulating members
63, 64 formed by, for example, a quartz ring, and heat transfer
members 73, 74 formed by an elastic body having adhesiveness are
buried in the notches. In this case, heat transfer members 73, 74
are installed in insulating members 63, 64, respectively, so that
the top surfaces thereof are closely attached to focus ring 5 and
the bottom surfaces thereof are closely attached to placing table
3.
[0063] Even in these configurations, since insulating members 63,
64 are installed to be adjacent to both left and right sides of
heat transfer members 73, 74 between placing table 3 and focus ring
5, the same effect as the second exemplary embodiment can be
acquired.
[0064] In a configuration of the example shown in FIGS. 10A, 10B
and 10C in which the insulating member and the heat transfer member
are installed in the concentric pattern with corresponding placing
area 32 outside placing area 32, insulating members 65a to 65c and
sheet type heat transfer members 75a, 75b are installed to be
laminated in the diameter direction of wafer W on placing table 3.
In this configuration, as shown in FIGS. 10A and 10B, insulating
members 65a to 65c made by the quartz rings are prepared and
annular thin sheet type heat transfer members 75a, 75b of which
both sides are sandwiched by two insulating members 65a, 65b; 65b,
65c. Heat transfer members 75a, 75b are installed in insulating
members 65a to 65c so that the top surface thereof is closely
attached to focus ring 5 and the bottom surface thereof is closely
attached to placing table 3.
[0065] Herein, both the top and the bottom ends of heat transfer
members 75a, 75b are installed to be closely attached to the bottom
surface of focus ring 5 and the top and the bottom surfaces of
placing table 3, respectively, in order to thermally contact focus
ring 5 and placing table 3. In this case, as shown in FIG. 10C,
both the top and the bottom ends of heat transfer member 75a, 75b
are installed to protrude from the top surfaces and the bottom
surfaces of insulating members 65a to 65c, and groove portions 50,
30 corresponding to the protruded portions are provided on the
bottom surface of focus ring 5 and the top surface of placing table
3, and heat transfer member 75a, 75b may be closely attached to
focus ring 5 and placing table 3 through the protruded portions and
groove portions 50, 30.
[0066] Even in this configuration, since insulating members 65a to
65c and heat transfer members 75a, 75b are installed such that
insulating member 65 is placed to be adjacent to both left and
right sides of heat transfer member 75 between placing table 3 and
focus ring 5, the same effect as the second exemplary embodiment
can be acquired.
[0067] Continuously, a third exemplary embodiment of the present
disclosure will be described with reference to FIGS. 11A and 11B.
In this example, a plurality of lower heat transfer members 76a are
installed between an insulating member 66 and placing table 3, and
a plurality of upper heat transfer members 76b are installed
between insulating member 66 and focus ring 5. The plurality of
lower heat transfer members 76a are closely attached to both the
top surfaces of insulating member 66 and placing table 3 between
the top surfaces thereof, and installed in a ring type along the
focus ring and to be spaced apart from one another in a diameter
direction of focus ring 5, respectively. The plurality of upper
heat transfer members 75b are closely attached to both sides
between the bottom surfaces of insulating member 66 and focus ring
5, and installed in the ring type along focus ring 5 to be spaced
apart from one another in the diameter direction of focus ring 5,
respectively.
[0068] Specifically, as shown in FIG. 11B, for example, plural rows
(e.g., four rows) of annular sheet type lower heat transfer members
76a and upper heat transfer members 76b are attached to the top and
the bottom of insulating member 66 made by, for example, the quartz
ring. A plurality of notch portions 77 are formed in heat transfer
members 76a, 76b in the circumferential direction, respectively, so
that a space between heat transfer members 76a, 76b adjacent to
each other in the diameter direction of focus ring 5 is allowed to
communicate with atmosphere in processing chamber 20. In this
example, lower heat transfer member 76a and upper heat transfer
member 76b of insulating member 66 are installed so as not to be
vertically overlapped with each other, but heat transfer members
76a, 76b may be installed to be vertically overlapped with each
other. Notch portions 77 may be formed on at least one of lower
heat transfer member 76a and upper heat transfer member 76b.
[0069] In this configuration, since the heat of focus ring 5 moves
in a path of upper heat transfer member 76b, insulating member 66,
lower heat transfer member 76a, and placing table 3 in this order
during plasma processing, focus ring 5 is cooled down during the
plasma processing. As a result, the amount of the polymers attached
to the periphery of the rear surface of wafer W can be reduced as
in the first exemplary embodiment. Since heat transfer members 76a,
76b are installed in the concentric pattern with placing area 32,
focus ring 5 can be substantially uniformly cooled down along the
circumferential direction thereof.
[0070] Since heat transfer members 76a, 76b is surface-contacted
with insulating member 66, there is a concern that air bubbles will
be mixed into a portion between insulating member 66 and heat
transfer members 76a, 76b during an adhesion. In this case, since
notch portions 77 are formed in heat transfer members 76a, 76b,
when processing chamber 20 is vacuum-exhausted, the air bubbles are
discharged from notch portions 77, and as a result, the air bubbles
hardly exist between insulating member 66 and heat transfer members
76a, 76b during plasma processing. As a result, since contact
states between heat transfer members 76a, 76b and insulating member
66 are constant in a plane (on the entire bottom of focus ring 5),
the heat of focus ring 5 moves toward placing table 3 almost
uniformly in the plane to almost uniformly adjust the temperature
of focus ring 5.
[0071] In the present disclosure as described above, as shown in
FIG. 12A, a case in which the height positions of the bottom
surfaces of focus ring 5 are different from each other in the
diameter direction of wafer W on placing table 3 is included as
well in the scope of the present disclosure. As shown in FIG. 12B,
for example, when an insulating member 68 and a heat transfer
member 78 are arranged to be lined up in the diameter direction of
wafer W, a case in which a part of heat transfer member 78 enters
into insulating member 68 so that insulating member 68 and heat
transfer member 78 are thus laminated vertically in a part of the
diameter direction is also included in the scope of the present
disclosure.
[0072] As shown in FIG. 13, an insulating member 69 is installed in
the concentric pattern with respect to the center of wafer W on
placing table 3 between the top surface of placing table 3 and the
bottom surface of focus ring 5. And a heat transfer member 79 may
be installed along focus ring 5 to be closely attached to outer
surfaces across the outer surfaces of placing table 3, insulating
member 69 and focus ring 5. Even in this configuration, since the
heat of focus ring 5 is transferred to placing table 3 through heat
transfer member 79, focus ring 5 is cooled down during the plasma
processing. In this case, heat transfer member 79 may be configured
in the annular pattern and installed to be spaced apart from each
other in the concentric pattern with respect to the center of wafer
W on placing table 3.
Example
[0073] Wafer W was plasma-processed by using the plasma etching
apparatus of FIG. 1 and the temperature change of focus ring 5 was
measured. Specifically, five wafers W were continuously
plasma-processed by supplying CF-based gas as the processing gas to
measure the temperature of focus ring 5 with a thermometer using
interference of low-coherence light under the condition that 1200 W
high-frequency power was supplied from plasma generating
high-frequency power supply unit 46, and the temperature of wafer W
on placement area 32 was set to 30.degree. C. The quartz ring was
used as insulating member 6 and a heat transfer sheet formed with a
thickness of 0.5 mm of the high-molecular silicon gel filled with
alumina was used as heat transfer member 7. As a Comparative
Example, the same plasma processing was performed even with respect
to the case in which heat transfer member 7 was not installed and
the temperature of focus ring 5 at that time was measured.
[0074] This result is shown in FIG. 14. It is understood from the
Comparative Example and the Example that the temperature of focus
ring 5 is raised so that the heat from plasma is absorbed at the
plasma generation timing. However, in the Example, it could be seen
that the temperature of focus ring 5 is not substantially changed
even though a processing time elapsed, the heat of focus ring 5
moves to placing table 3 and accumulation of the heat in focus ring
5 is suppressed due to the installation of heat transfer member 7,
and, as a result, the temperature of focus ring 5 was cooled down
to approximately 50.degree. C. Meanwhile, in the Comparative
Example, it is understood that the temperature of focus ring 5 is
raised with the processing time elapsed and when plasma is
continuously irradiated, heat is accumulated in focus ring 5, and
as a result, the temperature of focus ring 5 was raised to
approximately 230.degree. C.
[0075] As described above, the present disclosure can be applied to
a plasma processing apparatus that plasma-processes a substrate
such as a glass substrate for a flat panel display (FPD) in
addition to a semiconductor wafer W. The present disclosure can be
applied to a plasma processing apparatus that performs a plasma
processing such as an ashing process, a chemical vapor deposition
(CVD), or a plasma treatment in addition to an etching process.
[0076] From the foregoing, it will be appreciated that various
embodiments of the present disclosure have been described herein
for purposes of illustration, and that various modifications may be
made without departing from the scope and spirit of the present
disclosure. Accordingly, the various embodiments disclosed herein
are not intended to be limiting, with the true scope and spirit
being indicated by the following claims.
* * * * *