U.S. patent application number 13/129607 was filed with the patent office on 2011-10-06 for plasma processing apparatus and plasma processing method.
This patent application is currently assigned to TOKYO ELECTRON LIMITED. Invention is credited to Naoki Matsumoto, Nobuyuki Okayama.
Application Number | 20110240598 13/129607 |
Document ID | / |
Family ID | 42198081 |
Filed Date | 2011-10-06 |
United States Patent
Application |
20110240598 |
Kind Code |
A1 |
Okayama; Nobuyuki ; et
al. |
October 6, 2011 |
PLASMA PROCESSING APPARATUS AND PLASMA PROCESSING METHOD
Abstract
A plasma processing apparatus 11 includes a reactant gas supply
unit 13 for supplying a reactant gas for a plasma process into a
processing chamber 12. The reactant gas supply unit 13 includes a
first reactant gas supply unit 61 provided at a center of a
dielectric plate 16 and configured to supply the reactant gas in a
directly downward direction toward a central region of a processing
target substrate W held on a holding table 14; and a second
reactant gas supply unit 62 provided at a position directly above
the holding table 14 but not directly above the processing target
substrate W held on the holding table 14 and configured to supply
the reactant gas toward a center of the processing target substrate
W held on the holding table 14.
Inventors: |
Okayama; Nobuyuki; ( Hyogo,
JP) ; Matsumoto; Naoki; ( Hyogo, JP) |
Assignee: |
TOKYO ELECTRON LIMITED
Minato-ku, Tokyo
JP
|
Family ID: |
42198081 |
Appl. No.: |
13/129607 |
Filed: |
August 25, 2009 |
PCT Filed: |
August 25, 2009 |
PCT NO: |
PCT/JP2009/064778 |
371 Date: |
June 20, 2011 |
Current U.S.
Class: |
216/69 ;
156/345.27; 156/345.33; 156/345.36; 156/345.51 |
Current CPC
Class: |
H01J 37/32192 20130101;
C23C 16/4558 20130101; C23C 16/452 20130101; H01J 37/3244
20130101 |
Class at
Publication: |
216/69 ;
156/345.51; 156/345.33; 156/345.36; 156/345.27 |
International
Class: |
C23F 1/00 20060101
C23F001/00; C23F 1/08 20060101 C23F001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 18, 2008 |
JP |
2008-294049 |
Nov 18, 2008 |
JP |
2008-294050 |
Claims
1. A plasma processing apparatus comprising: a processing chamber
configured to perform therein a plasma process on a processing
target substrate; a holding table provided within the processing
chamber and configured to hold the processing target substrate
thereon; a plasma generating unit configured to generate plasma
within the processing chamber; and a reactant gas supply unit
configured to supply a reactant gas for the plasma process into the
processing chamber, wherein the reactant gas supply unit comprises:
a first reactant gas supply unit configured to supply the reactant
gas in a directly downward direction toward a central region of the
processing target substrate held on the holding table; and a second
reactant gas supply unit provided at a position directly above the
holding table but not directly above the processing target
substrate held on the holding table, and configured to supply the
reactant gas toward a center of the processing target substrate
held on the holding table.
2. The plasma processing apparatus of claim 1, wherein the second
reactant gas supply unit is provided in the vicinity of the holding
table.
3. The plasma processing apparatus of claim 1, wherein the second
reactant gas supply unit is configured to supply the reactant gas
in an inclined direction toward a central region of the processing
target substrate held on the holding table.
4. The plasma processing apparatus of claim 1, wherein the second
reactant gas supply unit is configured to supply the reactant gas
in a horizontal direction toward the center of the processing
target substrate held on the holding table.
5. The plasma processing apparatus of claim 1, wherein the second
reactant gas supply unit comprises a ring-shaped member, and the
ring-shaped member is provided with a supply hole through which the
reactant gas is supplied.
6. The plasma processing apparatus of claim 5, wherein the
processing target substrate is of a circular plate shape, the
ring-shaped member is of a circular ring shape, and an inner
diameter of the ring-shaped member is larger than an outer diameter
of the processing target substrate.
7. The plasma processing apparatus of claim 1, wherein the
processing chamber comprises a bottom positioned under the holding
table and a sidewall upwardly extending from a periphery of the
bottom, and the second reactant gas supply unit is embedded within
the sidewall.
8. The plasma processing apparatus of claim 7, wherein the sidewall
comprises an inwardly projecting protrusion, and the second
reactant gas supply unit is embedded within the protrusion.
9. The plasma processing apparatus of claim 1, wherein the plasma
generating unit comprises a microwave generator capable of
generating a microwave for exciting plasma and a dielectric plate
positioned to face the holding table and configured to introduce
the microwave into the processing chamber, and the first reactant
gas supply unit is provided at a central portion of the dielectric
plate.
10. The plasma processing apparatus of claim 1, further comprising:
a first temperature controller configured to control a temperature
of the central region of the processing target substrate held on
the holding table; and a second temperature controller configured
to control a temperature of an edge region of the processing target
substrate held on the holding table.
11. The plasma processing apparatus of claim 10, wherein the first
and second temperature controllers are provided within the holding
table.
12. The plasma processing apparatus of claim 10, wherein at least
one of the first and second temperature controllers is divided into
a plurality of members.
13. The plasma processing apparatus of claim 1, wherein the
processing chamber comprises a bottom positioned under the holding
table and a sidewall upwardly extending from a periphery of the
bottom, and the apparatus further comprises a sidewall temperature
controller configured to control a temperature of the sidewall.
14. The plasma processing apparatus of claim 12 13, wherein the
sidewall temperature controller is provided within the
sidewall.
15. A plasma processing method for performing a plasma process on a
processing target substrate, the method comprising: holding the
processing target substrate on a holding table provided within the
processing chamber; generating a microwave for exciting plasma;
introducing the microwave into the processing chamber through a
dielectric plate; and supplying a reactant gas in a directly
downward direction from a central portion of the dielectric plate
toward a central region of the processing target substrate, and
supplying the reactant gas in an inclined direction toward the
processing target substrate from a position directly above the
holding table but not directly above the processing target
substrate held on the holding table.
16. A plasma processing apparatus comprising: a holding table
configured to hold a processing target substrate thereon; a
processing chamber configured to perform therein a plasma process
on the processing target substrate, and having a bottom positioned
under the holding table and a ring-shaped sidewall upwardly
extending from a periphery of the bottom; a plasma generating unit
configured to generate plasma within the processing chamber; and a
reactant gas supply unit configured to supply a reactant gas for
the plasma process into the processing chamber, wherein the
reactant gas supply unit comprises: a first reactant gas supply
unit configured to supply the reactant gas in a directly downward
direction toward a central region of the processing target
substrate held on the holding table; and a second reactant gas
supply unit having a ring-shaped member provided at an upper
position of the holding table and at a position deviated from a
vertically upper region of the processing target substrate held on
the holding table and at an inside position of the sidewall, and
configured to supply the reactant gas toward a center of the
processing target substrate held on the holding table.
17. The plasma processing apparatus of claim 16, wherein the
ring-shaped member is provided at an outside position of the
holding table.
18. The plasma processing apparatus of claim 16, further
comprising: a first temperature controller configured to control a
temperature of the central region of the processing target
substrate held on the holding table; and a second temperature
controller configured to control a temperature of an edge region of
the processing target substrate held on the holding table.
19. The plasma processing apparatus of claim 18, wherein the first
and second temperature controllers are provided within the holding
table.
20. The plasma processing apparatus of claim 18, wherein at least
one of the first and second temperature controllers is divided into
a plurality of members.
Description
TECHNICAL FIELD
[0001] The present invention relates to a plasma processing
apparatus and a plasma processing method; and, more particularly,
to a plasma processing apparatus and a plasma processing method for
generating plasma by using a microwave as a plasma source.
BACKGROUND ART
[0002] A semiconductor device such as a LSI (Large Scale Integrated
circuit) is manufactured by performing various processes such as
etching, CVD (Chemical Vapor Deposition), sputtering or the like on
a semiconductor substrate (wafer) as a processing target substrate.
A processing method using plasma as an energy source, i.e., plasma
etching, plasma CVD or plasma sputtering may be used to perform the
etching, the CVD or the sputtering process. There are known various
kinds of plasma such as parallel plate type plasma, ICP
(Inductively-Coupled Plasma) and ECR (Electron Cyclotron Resonance)
Plasma, and plasma generated by various apparatuses is used for a
plasma process.
[0003] When the plasma etching or the like is performed on the
processing target substrate, a reactant gas for processing the
processing target substrate needs to be supplied into a processing
chamber for generating plasma therein. Here, a technology for
supplying the reactant gas into the processing chamber during the
plasma process of the processing target substrate is described in
Japanese Patent Laid-open Publication No. 2004-165374 (Patent
Document 1) or Japanese Patent Laid-open Publication No. H6-112163
(Patent Document 2). In the Patent Document 1, an annular gas ring
is provided between a mounting table for mounting thereon a
processing target object and a main coil in a plasma processing
apparatus using ECR plasma. The gas ring has a diameter larger than
that of the mounting table. The reactant gas is supplied by the gas
ring. In the Patent Document 2, a gas inlet for a deposition gas is
provided in the vicinity of a sample holding table in a plasma
processing apparatus using ECR plasma.
[0004] Patent Document 1: Japanese Patent Laid-open Publication No.
2004-165374
[0005] Patent Document 2: Japanese Patent Laid-open Publication No.
H6-112163
DISCLOSURE OF THE INVENTION
[0006] [Problems to Be Solved by the Invention]
[0007] When processing a processing target substrate, it may be
desirable to process the processing target substrate uniformly over
the entire surface thereof. When a reactant gas is supplied into
the processing chamber, the reactant gas may be supplied from a
multiple number of places in order to improve uniformity of the
plasma process within the surface of the processing target object.
FIG. 21 is a schematic cross sectional view illustrating a part of
a plasma processing apparatus 101 in which two reactant gas supply
units for supplying reactant gases into a processing chamber are
provided at two different positions. In the plasma processing
apparatus 101 shown in FIG. 21, in order to supply a reactant gas
to a central region of a circular plate-shaped processing target
substrate W, a first reactant gas supply unit 104 is provided in a
central portion of a dielectric plate 103 which introduces a
microwave into a processing chamber 102. The first reactant gas
supply unit 104 discharges the reactant gas toward the central
region of the processing target substrate W. Further, in order to
supply the reactant gas to an edge region of the processing target
substrate W, a second reactant gas supply unit 106 is provided in
an upper portion of a sidewall 105 of the processing chamber 102.
In the plasma processing apparatus 101 during a plasma process,
evacuation is performed in a downward direction by a gas exhaust
unit (not shown) located at a lower side of FIG. 21.
[0008] In the plasma processing apparatus 101 in which the two
reactant gas supply units are provided at the two different
positions as described above, when the reactant gas is supplied
into the processing chamber 102 at a pressure range (equal to or
larger than about 50 mTorr) of a viscous flow, the reactant gas
supplied from the second reactant gas supply unit 106 is affected
by the first reactant gas supply unit 104 and flows toward the
central portion, as indicated by an arrow X of FIG. 21. That is,
the reactant gas from the second reactant gas supply unit 106 flows
along the same supply path as that of the reactant gas from the
first reactant gas supply unit 104. Accordingly, an effect of
supplying the reactant gas from the second reactant gas supply unit
106 is not much. The reactant gas supplied to the central region of
the processing target substrate W is diffused in a radial direction
from the central region toward the edge region of the processing
target substrate. As the reactant gas flows toward the edge region,
the reactant gas is consumed and a reaction product increases. As a
result, distribution of a processed state on the processing target
substrate W is not uniform in a diametric direction of the
processing target substrate W, resulting in non-uniformity of a
processed surface.
[0009] Meanwhile, at a pressure range (equal to or less than about
50 mTorr) of a molecular flow, the reactant gas supplied from the
second reactant gas supply unit 106 flows in a downward direction,
as indicated by an arrow Y of FIG. 21, due to the evacuation by the
gas exhaust unit. Accordingly, the reactant gas supplied from the
second reactant gas supply unit 106 is exhausted without reaching
the processing target substrate W. As a result, only the reactant
gas from the first reactant gas supply unit 104 may reach the
processing target substrate W. Thus, as in the aforementioned case,
the processed state of the processing target substrate W may be
become non-uniform within the surface thereof.
[0010] As stated above, in the plasma processing apparatus 101
having the above-described configuration, even if a supply amount
of the gas from the second reactant gas supply unit 106 is adjusted
by varying an internal pressure of the processing chamber 102, the
reactant gas may not be uniformly supplied to the processing target
substrate W. Thus, it may be difficult to achieve uniformity of the
plasma process within the surface of the processing target
substrate W. In the plasma processing apparatuses described in
Patent Document 1 and Patent Document 2, the above-mentioned
problem may be encountered.
[0011] Here, in case that the second reactant gas supply unit is
provided in a position directly above the processing target
substrate W so as to supply the reactant gas to the processing
target substrate W uniformly, the following problems may be caused.
FIG. 22 is a schematic cross sectional view showing a part of a
plasma processing apparatus 111 having such a configuration, and
FIG. 22 corresponds to the cross section illustrated in FIG. 21. As
shown in FIG. 22, in the plasma processing apparatus 111, a first
reactant gas supply unit 113 is provided in a central portion of a
dielectric plate 112, and a ring-shaped second reactant gas supply
unit 115 is provided in a position directly above a processing
target substrate W held on a holding table 114. A reactant gas is
supplied to an edge region of the processing target substrate W in
a directly downward direction by the second reactant gas supply
unit 115.
[0012] In this configuration, however, the reactant gas supplied
from the first reactant gas supply unit 113 and the reactant gas
supplied from the second reactant gas supply unit 115 may collide
with each other in a region 116 between the central region and the
edge region of the processing target substrate W in a diametric
direction. In FIG. 22, the region 116 is marked by a dashed line.
The reactant gas may stay in this region 116, thus resulting in
stay of a deposit (reaction product).
[0013] Further, as shown in FIG. 22, if the second reactant gas
supply unit is provided in the position directly above the
processing target substrate W, the second reactant gas supply unit
may become a plasma shield that blocks a flow of plasma above the
processing target substrate W. Such a plasma shield may cause
non-uniformity of the plasma process on the processing target
substrate W.
[0014] Due to the stay of the deposit and the presence of the
plasma shield as mentioned above, an etching rate of the processing
target substrate W in the region 116 and an etching rate of the
processing target substrate W in the central region or the edge
region become different, resulting in deterioration of uniformity
of the plasma process within the surface of the processing target
substrate W.
[0015] The present invention provides a plasma processing apparatus
capable of improving uniformity of a plasma process within a
surface of a processing target substrate.
[0016] The present invention also provides a plasma processing
method capable of improving uniformity of a plasma process within a
surface of a processing target substrate.
[0017] [Means for Solving the Problems]
[0018] In accordance with one aspect of the present invention,
there is provided a plasma processing apparatus including a
processing chamber configured to perform therein a plasma process
on a processing target substrate; a holding table provided within
the processing chamber and configured to hold the processing target
substrate thereon; a plasma generating unit configured to generate
plasma within the processing chamber; and a reactant gas supply
unit configured to supply a reactant gas for the plasma process
into the processing chamber. The reactant gas supply unit includes
a first reactant gas supply unit configured to supply the reactant
gas in a directly downward direction toward a central region of the
processing target substrate held on the holding table; and a second
reactant gas supply unit provided at a position directly above the
holding table but not directly above the processing target
substrate held on the holding table, and configured to supply the
reactant gas toward a center of the processing target substrate
held on the holding table.
[0019] In accordance with this plasma processing apparatus, the
reactant gas can be uniformly supplied to the entire processing
target substrate by both the first reactant gas supply unit
configured to supply the reactant gas in the directly downward
direction toward the central region of the processing target
substrate W and the second reactant gas supply unit configured to
supply the reactant gas toward the center of the processing target
substrate. Further, since the reactant gases supplied from the
first and second reactant gas supply units do not stay on the
processing target substrate, stay of deposits (reaction products)
can be suppressed. Furthermore, the second reactant gas supply unit
does not block a flow of plasma toward the processing target
substrate. Accordingly, uniformity of the plasma process within the
surface of the processing target substrate can be improved.
Further, the "the position directly above the processing target
substrate" refers to a vertically upper region of the processing
target substrate, and the "the center of the processing target
substrate" refers to the central region of the processing target
substrate and a vertically upper region of the central region of
the processing target substrate.
[0020] Desirably, the second reactant gas supply unit may be
provided in the vicinity of the holding table.
[0021] More desirably, the second reactant gas supply unit may be
configured to supply the reactant gas in an inclined direction
toward a central region of the processing target substrate held on
the holding table.
[0022] Further, the second reactant gas supply unit may be
configured to supply the reactant gas in a horizontal direction
toward the center of the processing target substrate held on the
holding table.
[0023] More desirably, the second reactant gas supply unit may
include a ring-shaped member, and the ring-shaped member may be
provided with a supply hole through which the reactant gas is
supplied.
[0024] More desirably, the processing target substrate may be of a
circular plate shape, the ring-shaped member may be of a circular
ring shape, and an inner diameter of the ring-shaped member may be
larger than an outer diameter of the processing target
substrate.
[0025] Moreover, the processing chamber may include a bottom
positioned under the holding table and a sidewall upwardly
extending from a periphery of the bottom, and the second reactant
gas supply unit may be embedded within the sidewall.
[0026] More desirably, the sidewall may include an inwardly
projecting protrusion, and the second reactant gas supply unit may
be embedded within the protrusion.
[0027] Further, in a desirable embodiment, the plasma generating
unit may include a microwave generator capable of generating a
microwave for exciting plasma and a dielectric plate positioned to
face the holding table and configured to introduce the microwave
into the processing chamber, and the first reactant gas supply unit
may be provided at a central portion of the dielectric plate.
[0028] More desirably, the plasma processing apparatus may further
include a first temperature controller configured to control a
temperature of the central region of the processing target
substrate held on the holding table; and a second temperature
controller configured to control a temperature of an edge region of
the processing target substrate held on the holding table.
[0029] More desirably, at least one of the first and second
temperature controllers may be divided into a plurality of
members.
[0030] Further, in a desirable embodiment, the first and second
temperature controllers may be provided within the holding
table.
[0031] More desirably, the processing chamber may include a bottom
positioned under the holding table and a sidewall upwardly
extending from a periphery of the bottom, and the plasma processing
apparatus may further include a sidewall temperature controller
configured to control a temperature of the sidewall.
[0032] More desirably, the sidewall temperature controller may be
provided within the sidewall.
[0033] In accordance with another aspect of the present invention,
there is provided a plasma processing method for performing a
plasma process on a processing target substrate. The plasma
processing method includes holding the processing target substrate
on a holding table provided within the processing chamber;
generating a microwave for exciting plasma; introducing the
microwave into the processing chamber through a dielectric plate;
and supplying a reactant gas in a directly downward direction from
a central portion of the dielectric plate toward a central region
of the processing target substrate, and supplying the reactant gas
in an inclined direction toward the processing target substrate
from a position directly above the holding table but not directly
above the processing target substrate held on the holding
table.
[0034] In accordance with still another aspect of the present
invention, there is provided a plasma processing apparatus
including a holding table configured to hold a processing target
substrate thereon; a processing chamber configured to perform
therein a plasma process on the processing target substrate, and
having a bottom positioned under the holding table and a
ring-shaped sidewall upwardly extending from a periphery of the
bottom; a plasma generating unit configured to generate plasma
within the processing chamber; and a reactant gas supply unit
configured to supply a reactant gas for the plasma process into the
processing chamber. The reactant gas supply unit includes a first
reactant gas supply unit configured to supply the reactant gas in a
directly downward direction toward a central region of the
processing target substrate held on the holding table; and a second
reactant gas supply unit having a ring-shaped member provided at an
upper position of the holding table and at a position deviated from
a vertically upper region of the processing target substrate held
on the holding table and at an inside position of the sidewall, and
configured to supply the reactant gas toward a center of the
processing target substrate held on the holding table.
[0035] Desirably, the ring-shaped member may be provided at an
outside position of the holding table.
[0036] More desirably, the plasma processing apparatus may include
a first temperature controller configured to control a temperature
of the central region of the processing target substrate held on
the holding table; and a second temperature controller configured
to control a temperature of an edge region of the processing target
substrate held on the holding table.
[0037] More desirably, the first and second temperature controllers
may be provided within the holding table.
[0038] More desirably, at least one of the first and second
temperature controllers may be divided into a plurality of
members.
[0039] [Effect of the Invention]
[0040] In accordance with the plasma processing apparatus and the
plasma processing method of the present invention, the reactant gas
can be uniformly supplied to the entire processing target substrate
by both the first reactant gas supply unit for supplying the
reactant gas in the directly downward direction toward the
processing target substrate and the second reactant gas supply unit
for supplying the reactant gas toward the processing target
substrate in the inclined direction. Further, since the reactant
gases supplied from the first and second reactant gas supply units
do not stay on the processing target substrate, stay of deposits
(reaction products) can be suppressed. Furthermore, the second
reactant gas supply unit does not block a flow of plasma toward the
processing target substrate. Accordingly, uniformity of the plasma
process within the surface of the processing target substrate can
be improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] FIG. 1 is a schematic cross sectional view illustrating
major components of a plasma processing apparatus in accordance
with an embodiment of the present invention;
[0042] FIG. 2 is a diagram illustrating the vicinity of a circular
ring-shaped member of a second reactant gas supply unit of the
plasma processing apparatus shown in FIG. 1, when viewed from a
direction of an arrow II of FIG. 1;
[0043] FIG. 3 is an enlarged view of a part III in the plasma
processing apparatus shown in FIG. 1;
[0044] FIG. 4 is a schematic diagram illustrating flows of reactant
gases from a first reactant gas supply unit and the second reactant
gas supply unit;
[0045] FIG. 5 illustrates a relationship between a film thickness
and a position on a processing target substrate W in a case of
setting an angle .theta. for supplying the reactant gas from the
second reactant gas supply unit to be about 42.degree. in the
plasma processing apparatus in accordance with the embodiment of
the present invention;
[0046] FIG. 6 illustrates a relationship between a film thickness
and a position on a processing target substrate W in a case of
setting an angle .theta. for supplying the reactant gas from the
second reactant gas supply unit to be about 24.degree. in the
plasma processing apparatus in accordance with the embodiment of
the present invention;
[0047] FIG. 7 illustrates an X axis, a Y axis, a V axis and a W
axis shown in FIGS. 5 and 6 on a processing target substrate W;
[0048] FIG. 8 is a schematic cross sectional view illustrating
major components of a plasma processing apparatus in accordance
with another embodiment of the present invention and FIG. 8
corresponds to FIG. 1;
[0049] FIG. 9 is a schematic cross sectional view illustrating
major components of a plasma processing apparatus in accordance
with still another embodiment of the present invention and FIG. 9
corresponds to FIG. 1;
[0050] FIG. 10 is a schematic cross sectional view illustrating
major components of a plasma processing apparatus in accordance
with still another embodiment of the present invention and FIG. 10
corresponds to FIG. 1;
[0051] FIG. 11 is a diagram showing a part of a second reactant gas
supply unit of the plasma processing apparatus of FIG. 10, when
viewed from a direction of an arrow XI of FIG. 10.
[0052] FIG. 12 is an enlarged view of a part of a second reactant
gas supply unit of the plasma processing apparatus of FIG. 10;
[0053] FIG. 13 is a graph showing a relationship between an etching
rate normalized value and a lot number of processing target
substrates respectively processed by the plasma processing
apparatus shown in FIG. 10 and by the plasma processing apparatus
shown in FIG. 21;
[0054] FIG. 14 is a graph showing a relationship between the number
of particles and a lot number of processing target substrates
processed by the plasma processing apparatus shown in FIG. 10;
[0055] FIG. 15 is a graph showing a relationship between a
center/edge flow rate ratio and a non-uniformity of a plasma
process on a processing target substrate processed by the plasma
processing apparatus of FIG. 10;
[0056] FIG. 16 is a graph showing a relationship between a film
thickness and a position on the processing target substrate W when
the processing target substrate W is processed by the plasma
processing apparatus of FIG. 10 at a center/edge flow rate ratio
indicated by an arrow G.sub.1 of FIG. 15;
[0057] FIG. 17 is a graph showing a relationship between a film
thickness and a position on the processing target substrate W when
the processing target substrate W is processed in the plasma
processing apparatus of FIG. 10 at a center/edge flow rate ratio
indicated by an arrow G.sub.2 of FIG. 15;
[0058] FIG. 18 is a graph showing a relationship between a film
thickness and a position on the processing target substrate W when
the processing target substrate W is processed in the plasma
processing apparatus of FIG. 10 at a center/edge flow rate ratio
indicated by an arrow G.sub.3 of FIG. 15;
[0059] FIG. 19 is a schematic cross sectional view illustrating
major components of a plasma processing apparatus in accordance
with still another embodiment of the present invention and FIG. 19
corresponds to FIG. 1;
[0060] FIG. 20 is a schematic cross sectional view illustrating
major components of a plasma processing apparatus in accordance
with still another embodiment of the present invention and FIG. 20
corresponds to FIG. 1;
[0061] FIG. 21 is a schematic cross sectional view illustrating a
part of a conventional plasma processing apparatus in which two
reactant gas supply units for supplying reactant gases into a
processing chamber are provided at two different positions; and
[0062] FIG. 22 is a schematic cross sectional view showing a part
of a conventional plasma processing apparatus in which a second
reactant gas supply unit is provided directly above a processing
target substrate W and FIG. 22 corresponds to FIG. 21.
BEST MODE FOR CARRYING OUT THE INVENTION
[0063] Hereinafter, embodiments of the present invention will be
described with reference to the accompanying drawings. FIG. 1 is a
schematic cross sectional view illustrating major components of a
plasma processing apparatus in accordance with an embodiment of the
present invention. As depicted in FIG. 1, a plasma processing
apparatus 11 may include a processing chamber 12 for performing
therein a plasma process on a processing target substrate W; a
reactant gas supply unit 13 for supplying a reactant gas for the
plasma process into the processing chamber 12; a circular
plate-shaped holding table 14 for holding the processing target
substrate W thereon; a microwave generator 15 capable of generating
a microwave for plasma excitation; a dielectric plate 16 positioned
to face the holding table 14 and configured to introduce the
microwave generated by the microwave generator 15 into the
processing chamber 12; and a controller (not shown) capable of
controlling the entire plasma processing apparatus 11. The
controller controls processing conditions for performing the plasma
process on the processing target substrate W, such as a gas flow
rate in the reactant gas supply unit 13 and an internal pressure of
the processing chamber 12.
[0064] The processing chamber 12 may include a bottom 17 positioned
under the holding table 14 and a sidewall 18 extending upward from
the periphery of the bottom 17. The sidewall 18 has a cylindrical
shape. A gas exhaust hole 19 for gas exhaust is provided in the
bottom 17 of the processing chamber 12. A top of the processing
chamber 12 is opened and the processing chamber 12 can be
hermetically sealed by a dielectric plate 16 provided at the top of
the processing chamber 12 and by an O-ring 20 as a sealing member
provided between the dielectric plate 16 and the processing chamber
12.
[0065] The microwave generator 15 having a matching unit 21 is
connected to an upper portion of a coaxial waveguide 24 for
introducing a microwave via a mode converter 22 and a waveguide 23.
For example, a microwave of a TE mode generated by the microwave
generator 15 is converted to a TEM mode by the mode converter 22
after it passes through the waveguide 23. Then, the microwave of
the TEM mode propagates through the coaxial waveguide 24. The
coaxial waveguide 24 may include a central conductor 25 provided at
a center thereof in a diametric direction; and an external
conductor 26 provided at the outside of the central conductor 25 in
the diametric direction. An upper end of the central conductor 25
is connected to a ceiling partition wall of the mode converter 22.
A frequency of the microwave generated by the microwave generator
15 is, for example, about 2.45 GHz. Further, the waveguide 23 may
have a circular or a rectangular cross section.
[0066] The dielectric plate 16 is of a circular plate shape and is
made of a dielectric material. A ring-shaped tapered recess 27 is
provided on a bottom surface of the dielectric plate 16 to
facilitate generation of a standing wave by the introduced
microwave. Due to the recess 27, plasma can be efficiently
generated under the dielectric plate 16 by the microwave. Further,
the dielectric plate 16 may be made of a material such as, but not
limited to, quartz or alumina.
[0067] Further, the plasma processing apparatus 11 may include a
wavelength shortening plate 28 for propagating the microwave
introduced through the coaxial waveguide 24; and a thin circular
slot plate 30 for introducing the microwave to the dielectric plate
16 through a multiple number of slot holes 29. The microwave
generated by the microwave generator 15 is propagated to the
wavelength shortening plate 28 through the coaxial waveguide 24 and
is then introduced to the dielectric plate 16 through the slot
holes 29 provided in the slot plate 30. The microwave transmitted
through the dielectric plate 16 generates an electric field
directly under the dielectric plate 16. As a result, plasma is
generated within the processing chamber 12.
[0068] The holding table 14 also serves as a high frequency
electrode and is supported by a cylindrical insulating support 31
extending vertically upward from the bottom 17. A ring-shaped gas
exhaust passageway 33 is formed between the sidewall 18 of the
processing chamber 12 and a cylindrical conductive support 32
extending vertically upward from the bottom 17 along the outer
periphery of the cylindrical support 31. A ring-shaped baffle plate
34 provided with a multiple number of through holes is fixed to an
upper portion of the gas exhaust passageway 33. A gas exhaust unit
36 is connected to a bottom portion of the gas exhaust hole 19 via
a gas exhaust pipe 35. The gas exhaust unit 36 has a vacuum pump
such as a turbo molecular pump. The inside of the processing
chamber 12 can be depressurized to a desired vacuum level by the
gas exhaust unit 36.
[0069] The holding table 14 is electrically connected with a high
frequency RF bias power supply 37 via a matching unit 38 and a
power supply rod 39. The high frequency power supply 37 outputs a
high frequency power of a certain frequency, e.g., about 13.56 MHz,
suitable for controlling energy of ions attracted into the
processing target substrate W. The matching unit 38 has a matcher
for matching impedance on the side of the high frequency power
supply 37 with impedance on the side of a load such as an
electrode, plasma and the processing chamber 12. A blocking
capacitor for generation of self-bias is included in the
matcher.
[0070] An electrostatic chuck 41 configured to hold the processing
target substrate W by an electrostatic attracting force is provided
on a top surface of the holding table 14. Further, a focus ring 42
is provided at a periphery of the electrostatic chuck 41 in a
diametric direction to surround the processing target substrate W
in a ring shape. The electrostatic chuck 41 may include an
electrode 43 made of a conductive film sandwiched between a pair of
insulating films 44 and 45. The electrode 43 is electrically
connected with a high voltage DC power supply 46 via a switch 47
and a coated line 48. The processing target substrate W can be
attracted to and held on the electrostatic chuck 41 by a Coulomb
force generated by a DC voltage applied from the DC power supply
46.
[0071] A ring-shaped coolant path 51 extending in a circumferential
direction of the holding table 14 is provided within the holding
table 14. A coolant of a preset temperature, e.g., cooling water is
supplied into and circulated through the coolant path 51 from a
chiller unit (not shown) via pipes 52 and 53. A processing
temperature of the processing target substrate W on the
electrostatic chuck 41 can be controlled by adjusting the
temperature of the coolant. Further, a heat transfer gas from a
heat transfer gas supply unit (not shown), e.g., a He gas is
supplied to between a top surface of the electrostatic chuck 41 and
a rear surface of the processing target substrate W via a gas
supply pipe 54.
[0072] Now, a detailed configuration of the reactant gas supply
unit 13 for supplying a reactant gas for the plasma process into
the processing chamber 12 will be explained. The reactant gas
supply unit 13 may include a first reactant gas supply unit 61 for
supplying the reactant gas in a directly downward direction toward
the central region of the processing target substrate W; and a
second reactant gas supply unit 62 for supplying the reactant gas
toward the processing target substrate W in an inclined direction.
To elaborate, the first reactant gas supply unit 61 supplies the
reactant gas in a direction indicated by an arrow F.sub.1 of FIG.
1, while the second reactant gas supply unit 62 supplies the
reactant gas in a direction indicted by an arrow F.sub.2 of FIG. 1.
Here, the second reactant gas supply unit 62 supplies the reactant
gas toward a center of the processing target substrate W, i.e.,
toward the central region of the processing target substrate W. The
same kind of reactant gas is supplied to the first and second
reactant gas supply units 61 and 62 from a single reactant gas
supply source (not shown).
[0073] A configuration of the first reactant gas supply unit 62
will be first elaborated. The first reactant gas supply unit 61 is
provided at a center of the dielectric plate 16 in a diametric
direction and is located at an upper position of the dielectric
plate 16 from a bottom surface 63 of the dielectric plate 16 facing
the holding table 14. The dielectric plate 16 is provided with an
accommodation part 64 for accommodating the first reactant gas
supply unit 61 therein. An O-ring 65 is provided between the first
reactant gas supply unit 61 and the accommodation part 64 so as to
secure airtightness of the inside of the processing chamber
112.
[0074] The first reactant gas supply unit 61 is provided with a
multiple number of supply holes 66 through which the reactant gas
is discharged in a directly downward direction toward the central
region of the processing target substrate W. The supply holes 66
are provided in an area of the wall surface 67 facing the holding
table 14 and the area is exposed to the inside of the processing
chamber 12. Further, the wall surface 67 is flat. The supply holes
66 are provided in the first reactant gas supply unit 61 to be
located at the center of the dielectric plate 16 in the diametric
direction.
[0075] The plasma processing apparatus 11 is provided with a gas
flow path 68 formed through the central conductor 25 of the coaxial
waveguide 24, the slot plate 30 and the dielectric plate 16 to
reach the supply holes 66. A gas supply system 72 including an
opening/closing valve 70 and/or a flow rate controller 71 such as a
mass flow controller is connected to a gas inlet 69 formed at an
upper end of the central conductor 25. The reactant gas is supplied
while its flow rate is controlled by the gas supply system 72.
[0076] Now, a configuration of the second reactant gas supply unit
62 will be elaborated. FIG. 2 is a diagram illustrating a circular
ring-shaped member 73 included in the second reactant gas supply
unit 62 shown in FIG. 1 and its vicinity, when viewed from a
direction of an arrow II of FIG. 1. As depicted in FIGS. 1 and 2,
the second reactant gas supply unit 62 may include the ring-shaped
member 73 and holding members 74 that hold the ring-shaped member
73 from a higher position of the sidewall 18 than the ring-shaped
member 73. The ring-shaped member 73 is of a pipe shape and the
inside of the ring-shipped member 73 serves as a flow path of the
reactant gas. The ring-shaped member 73 is positioned between the
holding table 14 and the dielectric plate 16 within the processing
chamber 12.
[0077] Now, the ring-shaped member 73 will be elaborated. FIG. 3 is
an enlarged view of the ring-shaped member 73 indicated by a part
III of FIG. 1. As depicted in FIGS. 1 to 3, the ring-shaped member
73 may include a wall 79a straightly extending in a vertical
direction and located at an inner circumference of the ring-shaped
member 73; a wall 79b straightly extending in a vertical direction
and located at an outer circumference of ring-shaped member 73; a
wall 79c straightly extending in a left-right direction and located
on the side of the holding table 14; and a wall 79d straightly
extending in a slant direction so as to connect a lower end of the
wall 79a with an inner end of the wall 79c.
[0078] The ring-shaped member 73 is provided with a multiple number
of supply holes 75 through which the reactant gas is discharged in
an inclined direction toward the processing target substrate W.
Each supply hole 75 has a circular shape. The supply holes 75 are
provided in the wall 79d extending in the slant direction. To
elaborate, each supply hole 75 is formed by opening a part of the
wall 79d in a direction orthogonal to the wall 79d. An inclination
angle of the supply hole 75 may be selected depending on the
direction for supplying the reactant gas. Here, the inclination
angle of the supply hole 75 is the same as an angle of the inclined
direction for supplying the reactant gas by the second reactant gas
supply unit 62 and is defined as an angle .theta. between a
straight line (indicated by a dashed dotted line of FIG. 3)
extending in a left-right direction through a vertical center 78 of
the ring-shaped member 73 and a straight line 79e (indicated by a
dashed triple-dotted line of FIG. 3) extending in the direction
orthogonal to the wall 79d. The supply holes 75 are arranged at a
same distance from each other along a circumference of the
ring-shaped member 73. In the present embodiment, eight (8) supply
holes 75 are provided.
[0079] The holding member 74 is of a pipe shape. The reactant gas
supplied from the outside of the processing chamber 12 reaches the
ring-shaped member 73 through the inside of the holding member 74.
The holding member 74 has a substantially L-shaped cross section
and is inwardly protruded from an upper portion of the sidewall 18
and vertically extended in a downward direction. An end portion 76
of the holding member 74 extended in the downward direction is
connected with the ring-shaped member 73. A gas supply system (not
shown) including an opening/closing valve and a flow rate
controller as mentioned above may also be installed outside the
holding member 74.
[0080] In this embodiment, the second reactant gas supply unit 62
is located in a position directly above the holding table 14 but
not located directly above the processing target substrate W held
on the holding table 14. Specifically, if an inner diameter of the
ring-shaped member 73 is denoted by D.sub.1 and an outer diameter
of the processing target substrate W is denoted by D.sub.2, the
inner diameter D.sub.1 of the ring-shaped member 73 is set to be
larger than the outer diameter D.sub.2 of the processing target
substrate W. Further, the holding member 74 is also located at a
position which is not directly above the processing target
substrate W.
[0081] Desirably, the second reactant gas supply unit 62 may be
located at the vicinity of the holding table 14. Specifically, the
ring-shaped member 73 may be provided in a so-called downflow
region which is not affected by the reactant gas supplied from the
first reactant gas supply unit 61 and in which a plasma density is
low. A distance L.sub.1 from a top surface 77 of the processing
target substrate W held on the holding table 14 to the center 78 of
the ring-shaped member 73 indicated by the dashed dotted line of
FIG. 1 may be set to a preset value within about 90 mm.
[0082] Now, a method for performing a plasma process on a
processing target substrate W by the plasma processing apparatus 11
in accordance with the embodiment of the present invention will be
explained.
[0083] First, the processing target substrate W is held on the
electrostatic chuck 41 of the holding table 14 installed in the
processing chamber 12. Then, a microwave for exciting plasma is
generated by the microwave generator 15, and, then, the microwave
is introduced into the processing chamber 12 through the dielectric
plate 16 or the like. Then, a reactant gas is supplied in a
directly downward direction from a central portion of the
dielectric plate 16 toward a central region of the processing
target substrate W through the supply holes 66 of the first
reactant gas supply unit 61. Further, the reactant gas is also
supplied in an inclined direction toward the central region of the
processing target substrate W through the supply holes 75 of the
ring-shaped member 73 of the second reactant gas supply unit 62. In
this way, a plasma process is performed on the processing target
substrate W.
[0084] In accordance with the plasma processing apparatus 11 and
the plasma processing method as described above, the reactant gas
can be uniformly supplied to the entire processing target substrate
W by the first reactant gas supply unit 61 that supplies the
reactant gas in the directly downward direction toward the central
region of the processing target substrate W and by the second
reactant gas supply unit 62 that supplies the reactant gas in the
inclined direction toward the central region of the processing
target substrate W. Furthermore, since the reactant gases supplied
by the first and second reactant gas supply units 61 and 62 do not
stay on the processing target substrate W, stay of deposits on the
processing target substrate W can be suppressed. Moreover, the
second reactant gas supply unit 62 does not block a flow of plasma
toward the processing target substrate W. Accordingly, uniformity
of the plasma process within a surface of the processing target
substrate W can be improved.
[0085] Here, flows of the reactant gases supplied from the first
reactant gas supply unit 61 and the second reactant gas supply unit
62 of the plasma processing apparatus 11 having the above-described
configuration will be elaborated. FIG. 4 is a schematic diagram
illustrating the flows of the reactant gases supplied from the
first and second reactant gas supply units 61 and 62. In FIG. 4,
each component of the plasma processing apparatus 11 is illustrated
in a simplified manner. As can be seen from FIG. 4, the reactant
gas from the first reactant gas supply unit 61 is supplied in the
directly downward direction toward the central region of the
processing target substrate W as indicated by an arrow F.sub.1 of
FIG. 4 and then tends to flow upward after bouncing one time at a
position 80 in the vicinity of the central region of the processing
target substrate W marked by a dashed line of FIG. 4. Since,
however, the reactant gas from the second reactant gas supply unit
62 is supplied in a direction indicated by an arrow F.sub.2, the
reactant gas from the first reactant gas supply unit 61 is
suppressed from flowing upward after being bounced. Instead, the
reactant gas supplied from the first reactant gas supply unit 61
flows toward an edge region of the processing target substrate W in
a direction indicated by an arrow F.sub.3. Due to this mechanism,
stay of the reactant gas as illustrated in FIG. 22 may be
suppressed.
[0086] FIGS. 5 and 6 are graphs showing a relationship between a
film thickness and a position on the processing target substrate W
when a film is formed on the processing target substrate W by the
plasma processing apparatus 11 in accordance with the embodiment of
the present invention. In FIGS. 5 and 6, a vertical axis represents
a film thickness .ANG., and a horizontal axis indicates a distance
mm from a center O. Further, FIG. 7 illustrates an X axis, a Y
axis, a V axis and a W axis shown in FIGS. 5 and 6 on the
processing target substrate W. FIGS. 5 and 6 illustrate cases in
which an angle .theta. for supplying the reactant gas from the
second reactant gas supply unit 62 is varied. FIG. 5 illustrates a
case in which the angle .theta. for supplying the reactant gas from
the second reactant gas supply unit 62 is about 42.degree., and
FIG. 6 illustrates a case in which the angle .theta. for supplying
the reactant gas from the second reactant gas supply unit 62 is
about 24.degree.. In the cases of FIGS. 5 and 6, an inner diameter
of the ring-shaped member 73 is about 400 mm, and a distance
L.sub.1 as shown in FIG. 1 is about 90 mm. Further, FIG. 6
illustrates a case of using the plasma processing apparatus 11
configured as shown in FIG. 1 and the angle corresponds to an angle
for supplying the reactant gas from the second reactant gas supply
unit 62 toward the central region of the processing target
substrate W held on the holding table 14. In FIG. 5, a ratio
between a gas supply amount from the first reactant gas supply unit
61 and a gas supply amount from the second reactant gas supply unit
62 is about 32:68. Further, in FIG. 6, a ratio between a gas supply
amount from the first reactant gas supply unit 61 and a gas supply
amount from the second reaction gas supply unit 62 is about
27:73.
[0087] As can be seen from FIG. 5, in case that the angle for
supplying the reactant gas from the second reactant gas supply unit
62 is about 42.degree., although film thicknesses on the central
region and the edge region of the processing target substrate W are
slightly larger than film thicknesses on regions between the
central and edge regions and the graph of FIG. 5 is of a
substantially W shape, the film thicknesses are almost stabilized
and uniform. That is, uniformity of the plasma process in the
surface of the processing target substrate W is improved. Further,
as can be seen from FIG. 6, in case that the angle .theta. for
supplying the reactant gas from the second reactant gas supply unit
62 is about 24.degree., film thicknesses on the entire processing
target substrate W are substantially uniformed. That is, uniformity
of the plasma process in the surface of the processing target
substrate W is further improved.
[0088] In the plasma processing apparatus 11 having the
above-described configuration, the uniformity of the plasma process
in the surface of the processing target substrate W can be improved
by supplying the reactant gas from the second reactant gas supply
unit 62 in the inclined direction. Meanwhile, in the conventional
plasma processing apparatus as depicted in FIG. 22, uniformity of a
plasma process in the surface of the processing target substrate W
cannot be improved by, for example, adjusting a ratio of gas supply
amounts. That is, in the conventional plasma processing apparatus
as configured in FIG. 22, a processing degree in the surface of the
processing target substrate W hardly changes even if the ratio of
the gas supply amounts is adjusted.
[0089] Moreover, in the plasma processing apparatus in accordance
with the embodiment of the present invention, since respective
components of the second reactant gas supply unit 62 are provided
at positions other than directly above the processing target
substrate W, fatigue of each component of the second reactant gas
supply unit 62 due to plasma can be reduced. Thus, lifetime of the
second reactant gas supply unit 62 can be increased.
[0090] In addition, although the embodiment has been described for
the case that the second reactant gas supply unit includes the
ring-shaped member and the holding members for holding the
ring-shaped member from a higher position of the sidewall than the
ring-shaped member, the present invention may not be limited
thereto. By way of example, the second reactant gas supply unit may
include the ring-shaped member and supporting members straightly
extended from the sidewall of the processing chamber inwardly in a
diametric direction.
[0091] FIG. 8 is a schematic cross sectional view illustrating
major components of a plasma processing apparatus having such
supporting members and FIG. 8 corresponds to FIG. 1. In FIG. 8, the
same parts as those described in FIG. 1 will be assigned same
reference numerals and redundant description thereof will be
omitted. As illustrated in FIG. 8, a second reactant gas supply
unit 92 included in a plasma processing apparatus 91 and configured
to supply a reactant gas in an inclined direction toward a
processing target substrate W may include a ring-shaped member 93
that is supported by supporting members 94 straightly extended from
a sidewall 18 of the processing chamber 12 inwardly in a diametric
direction. The supporting member 94 has a hollow shape. The
reactant gas supplied from the outside of the plasma processing
apparatus 91 is introduced into a processing chamber 12 through
supply holes 95 of the ring-shaped member 93 via the inside of the
supporting member 94. With this configuration, the same effect as
mentioned above can also be achieved.
[0092] Moreover, although this embodiment has been described for
the case that the second reactant gas supply unit includes the
ring-shaped member and the holding members for holding the
ring-shaped member from a higher position of the sidewall than the
ring-shaped member, the present invention may not be limited
thereto. By way of example, the second reactant gas supply unit for
supplying the reactant gas in the inclined direction toward the
processing target substrate W may be embedded in a sidewall of the
processing chamber.
[0093] Furthermore, in the plasma processing apparatus, the
sidewall of the processing chamber may include an inwardly
projecting protrusion, and the second reactant gas supply unit may
be embedded in the protrusion.
[0094] FIG. 9 is a schematic cross sectional view illustrating
major components of a plasma processing apparatus having such a
protrusion and FIG. 9 corresponds to FIG. 1. In FIG. 9, the same
parts as those described in FIG. 1 will be assigned same reference
numerals and redundant description thereof will be omitted. As
illustrated in FIG. 9, a sidewall 82 of a plasma processing
apparatus 81 may include a protrusion 83 that is projected inward,
particularly, that is projected inward in a diametric direction.
The protrusion 83 is of a circular ring shape. A ring-shaped member
84 of a second reactant gas supply unit for supplying a reactant
gas in an inclined direction toward a processing target substrate W
is embedded in the protrusion 83. A multiple number of supply holes
85 provided in the ring-shaped member 84 is exposed and opened in a
wall surface 86 of the protrusion 83 extended in an inclined
direction. In this embodiment, the protrusion 83 is located at a
position directly above the holding table 14 but not directly above
the processing target substrate W. To elaborate, an inner diameter
of the protrusion 83, i.e., a distance D.sub.3 between two opposite
points on a wall surface 88 of the protrusion 83 in a diametric
direction is larger than an outer diameter D.sub.2 of the
processing target substrate W. Further, a gas flow path 89 is
formed within the sidewall 82 so as to be connected to the
ring-shaped member 84 from the outside of a processing chamber 87.
With this configuration, the same effect as described above can
also be achieved.
[0095] In such a case, the processing chamber 87 may have a bottle
neck structure as an overall shape in which an inner diameter of
the sidewall 82 above the ring-shaped member 84 is smaller than an
inner diameter of the sidewall 82 below the ring-shaped member
84.
[0096] Furthermore, in the above-described embodiment, each supply
hole of the ring-shaped member has a circular shape. However, the
present invention may not be limited thereto, and the supply hole
may have an elongated shape extending in a circumferential
direction or in a diametric direction. Moreover, in the
above-described embodiment, although the number of the supply holes
is 8, the present invention may not be limited thereto.
[0097] Besides, in the above-described embodiment, the ring-shaped
member includes a multiple number of walls respectively extending
in the vertical direction, the left-right direction and the slant
direction. However, the present invention may not be limited
thereto, and the ring-shaped member may have, but not limited to, a
curved wall portion. Further, in the cross sectional view of FIG.
3, the ring-shaped member may have a circular ring-shaped wall
portion.
[0098] Furthermore, in the above-described embodiment, the second
reactant gas supply unit includes the ring-shaped member. However,
the present invention may not be limited thereto, and the second
reactant gas supply unit may not include the ring-shaped member. By
way of example, supply holes may be provided in lower ends of a
multiplicity of holding members, and the reactant gas may be
supplied in an inclined direction toward the processing target
substrate W through these supply holes.
[0099] Moreover, in the above-described embodiment, the second
reactant gas supply unit supplies the reactant gas in the inclined
direction toward the central region of the processing target
substrate W held on the holding table. However, the present
invention may not be limited thereto, and the second reactant gas
supply unit may be configured to supply the reactant gas in a
horizontal direction toward the center of the processing target
substrate W held on the holding table. To be more specific,
referring to FIG. 3, an angle .theta. for supplying the reactant
gas from the second reactant gas supply unit may be set to be
.theta.=0. By setting the angle .theta. in this way, the same
effect as described above can also be achieved. That is, the
reactant gas can be uniformly supplied to the entire processing
target substrate W. Further, the reactant gases supplied from the
first and second reactant gas supply units may not stay on the
processing target substrate W, so that stay of deposits can be
suppressed.
[0100] Such a case will be elaborated with reference to the
accompanying drawings. FIG. 10 is a schematic cross sectional view
illustrating major components of a plasma processing apparatus in
such a case and FIG. 10 corresponds to FIG. 1. In FIG. 10, the same
parts as those illustrated in FIG. 1 will be assigned same
reference numerals and redundant description thereof will be
omitted. FIG. 11 is a diagram showing a part of a second reactant
gas supply unit of the plasma processing apparatus of FIG. 10, when
viewed from a direction of an arrow XI of FIG. 10. FIG. 12 is an
enlarged view of a part marked by XII of FIG. 10. A cross section
depicted in FIG. 10 corresponds to a diagram taken along a line X-X
of FIG. 11.
[0101] Referring to FIGS. 10 to 12, a plasma processing apparatus
201 in accordance with still another embodiment of the present
invention may include a second reactant gas supply unit 202
configured to supply a reactant gas in a horizontal direction
toward a center of a processing target substrate W held on a
holding table 14. The second reactant gas supply unit 202 may
include a circular ring-shaped member 208 and three protrusions
211a, 211b and 211c that are projected outward from an outer
surface of the circular ring-shaped member 208 in a diametric
direction. The three protrusions 211a to 211c are arranged at a
regular distance in a circumferential direction of the ring-shaped
member 208. To be specific, the three protrusions 211a to 211c are
formed at an interval of about 120.degree..
[0102] The second reactant gas supply unit 202 may be formed by
joining a flat ring-shaped first member 209a provided with
protrusions corresponding to the protrusions 211a to 211c and a
ring-shaped second member 209b having a substantially
one-side-opened rectangular cross section and provided with
protrusions corresponding to the protrusions 211a to 211c. As shown
in FIG. 12, the second reactant gas supply unit 202 has a
substantially rectangular cross section. That is, a gas flow path
210 formed by joining the first member 209a and the second member
209b is a space having a substantially rectangular cross section.
Further, the first and second members may be made of, but not
limited to, quartz.
[0103] The second reactant gas supply unit 202 is provided with
thirty six (36) supply holes 215 through which the reactant gas is
supplied into a processing chamber 12. The supply holes 215 are
formed so as to supply the reactant gas in a straightly diametric
direction toward an inside of the ring-shaped member 208. To
elaborate, each supply hole 215 is formed through an inner wall of
the second member 209b of the second reactant gas supply unit 202.
The supply holes 215 are formed at substantially midway positions
of the ring-shaped member 208 in a vertical direction. Each supply
hole 215 has a circular shape having a size of, e.g., about
.phi.0.5 mm. The supply holes 215 are opened by, e.g., laser. The
thirty six (36) supply holes 215 are arranged at a regular distance
on an inner surface 216 of the second reactant gas supply unit 202
in a circumferential direction thereof.
[0104] The second reactant gas supply unit 202 is installed in the
processing chamber 12 by being supported by three supports 212a,
212b and 212c provided at a sidewall 18 of the processing chamber
12. To elaborate, inner surfaces 214a, 214b and 214c of the three
supports 212a, 212b and 212c inwardly extended from the sidewall 18
in a diametric direction at an interval of about 120.degree. are
joined to outer surfaces 213a, 213b and 213c of the three
protrusions 211a, 211b and 211c of the second reactant gas supply
unit 202, respectively. With regard to an installation position of
the ring-shaped member 208 in a vertical direction, the ring-shaped
member 208 is installed in a so-called downflow region.
[0105] Here, the support 212a has a hollow shape, and the gas can
be supplied into the gas flow path 210 of the second reactant gas
supply unit 202 through the support 212a from the outside of the
processing chamber 12. Meanwhile, the other two supports 212b and
212c have solid shapes without allowing an inflow/outflow of the
gas. That is, in the second reactant gas supply unit 202, the gas
is introduced into the gas flow path 210 from the outside of the
processing chamber 12 through the support 212a and the protrusion
211a and then is discharged into the processing chamber 12 toward a
center of the processing target substrate W through the 36 supply
holes 215.
[0106] Further, the plasma processing apparatus 201 illustrated in
FIG. 10 may include a temperature control unit 203 embedded in the
holding table 14 and configured to control a temperature of the
processing target substrate W held on the holding table 14. The
temperature control unit 203 may include a first temperature
controller 204 for controlling a temperature of a central region of
the processing target substrate W held on the holding table 14; and
a second temperature controller 205 for controlling a temperature
of an edge region of the processing target substrate W held on the
holding table 14. Specifically, the first and second temperature
controllers 204 and 205 are, for example, heaters of which
temperatures are independently adjusted. The first temperature
controller 204 may be provided in a center of the holding table 14
in a diametric direction. The second temperature controller 205 is
of a ring-shape and is positioned outside the first temperature
controller 204 while a gap is provided between the first and second
temperature controllers in a diametric direction. The temperatures
of the central region and the edge region of the processing target
substrate W can be set to different temperatures by the first and
second temperature controllers 204 and 205. In this way, by
controlling the temperatures of the central and edge regions of the
processing target substrate W independently by the first and second
temperature controllers 204 and 205, uniformity of a plasma process
within a surface of the processing target substrate W can be
further improved. Besides, the first and second temperature
controllers 204 and 205 are separately controlled, and they may be
configured to control the temperatures by flowing a coolant, as in
the plasma processing apparatus 11 depicted in FIG. 1.
[0107] Moreover, in the plasma processing apparatus 201 illustrated
in FIG. 10, temperature controllers 206 and 207 may be provided
within the cylindrical sidewall 18 of the processing chamber 12 and
within a cover 217 provided on top of the sidewall 18,
respectively. Temperatures of the sidewall 18 and the cover 217 can
be adjusted by the temperature controllers 206 and 207.
Accordingly, an internal temperature of the processing chamber 12
can be stabilized and more uniform plasma process is enabled. The
temperature controllers 206 and 207 may be heaters or configured to
flow a coolant.
[0108] In accordance with the plasma processing apparatus 201
having the above-described configuration, the same effects as
described above can also be achieved. That is, uniformity of the
plasma process within the surface of the processing target
substrate W can be obtained.
[0109] In accordance with sill another embodiment, since the
ring-shaped member 208 of the second reactant gas supply unit 202
is configured as a separate member from the sidewall 18 or the
cover 17 and is supported within the processing chamber 12 by the
three supports 212a to 212c, the ring-shaped member 208 is kept
away from the temperature controllers 206 and 207 and, thus, a
temperature of the ring-shaped member 208 can be maintained stable.
Accordingly, the ring-shaped member 208 may not be affected by the
temperature control by the temperature controllers 206 and 207,
and, thus, a gas supply amount through the supply holes 215 of the
second reactant gas supply unit 202 can be stabilized.
[0110] FIG. 13 is a graph showing etching rate normalized values
when 40 lots are processed by the plasma processing apparatus shown
in FIG. 10 and in the conventional plasma processing apparatus
shown in FIG. 21. A horizontal axis represents a lot number, and a
vertical axis represents an etching rate normalized value. Here, a
first substrate of every lot is measured. An etching rate
normalized value is an index that indicates a degree of variation
of each etching rate from an average etching rate of all etching
samples when the average etching rate is defined as 1. In FIG. 13,
circles and a solid line represent the case of the plasma
processing apparatus of FIG. 10, and squares and a dashed line
represent the case of the conventional plasma processing apparatus
of FIG. 21.
[0111] Referring to FIG. 13, in case of the plasma processing
apparatus shown in FIG. 10, the etching rate normalized value
varies within a range equal to about 1.00 and less than about 1.01
between the lots. In contrast, in case of the conventional plasma
processing apparatus shown in FIG. 21, the etching rate normalized
value fluctuates within a range from about 0.98 to about 1.02. That
is, as compared to the case of the plasma processing apparatus of
FIG. 10 in which non-uniformity of the etching rate normalized
value is less than about 0.01, non-uniformity of the etching rate
normalized value in case of the plasma processing apparatus of FIG.
21 is larger than about 0.04. Thus, the graph shows that the
non-uniformity of etching rate normalized values between the lots
is greatly reduced in the plasma processing apparatus of FIG.
10.
[0112] FIG. 14 is a graph showing a relationship between the number
of particles and a lot number of processing target substrates
processed by the plasma processing apparatus shown in FIG. 10. A
horizontal axis represents a lot number, and a vertical axis
represents the number of particles. The lot numbers in FIG. 14 are
equal to the lot numbers in FIG. 13. Here, particles having a
diameter of about 130 nm are counted by a particle monitor (SP1)
(product of KLA-Tencor Corporation).
[0113] As can be seen from FIG. 14, a maximum value of the number
of particles in the plasma processing apparatus of FIG. 10 is 5,
and the number of particles is mostly less than 5 at each lot and
sometimes even zero. That is, the number of particles is greatly
reduced. In the plasma processing apparatus shown in FIG. 21, since
the dielectric plate is located in the vicinity of supply holes,
the supply holes may be exposed to strong plasma and particles may
be generated from an inner wall surface in which the supply holes
are provided. In contrast, in the plasma processing apparatus shown
in FIG. 10, since the ring-shaped member is provided in the
downflow region, the supply holes are not exposed to strong plasma
and particles may not be generated much.
[0114] FIG. 15 is a graph showing a relationship between a
center/edge flow rate ratio and a non-uniformity of a plasma
process on a processing target substrate processed by the plasma
processing apparatus of FIG. 10. A horizontal axis represents a
center/edge flow rate ratio (%), and a vertical axis represents a
process non-uniformity (%). Here, a center/edge flow rate ratio
refers to a ratio of a gas supply amount to an edge of the
processing target substrate with respect to a gas supply amount to
a center of the processing target substrate, i.e., a ratio of a gas
supply amount from the second reactant gas supply unit with respect
to a gas supply amount from the first reactant gas supply unit. To
elaborate, a flow rate ratio 0% means that a gas is supplied only
from the first reactant gas supply unit, and a flow rate ratio 70%
means that the gas supply amount from the first reactant gas supply
unit is 70% of a total gas supply amount and the gas supply amount
from the second reactant gas supply unit is about 30% of the total
gas supply amount. Furthermore, a process non-uniformity refers to
a value obtained by dividing a difference between a maximum etching
amount and a minimum etching amount in a surface of the processing
target substrate by a multipoint average value. As will be
described below, in case of a center-fast distribution, the process
non-uniformity becomes a plus value, whereas, in case of an
edge-fast distribution, the process non-uniformity becomes a minus
value.
[0115] FIG. 16 is a graph showing a relationship between a film
thickness and a position on the processing target substrate W when
the processing target substrate W is processed by the plasma
processing apparatus of FIG. 10 at a center/edge flow rate ratio of
about 0%, as indicated by an. arrow G.sub.1 of FIG. 15. FIG. 17 is
a graph showing a relationship between a film thickness and a
position on the processing target substrate W when the processing
target substrate W is processed by the plasma processing apparatus
of FIG. 10 at a center/edge flow rate ratio of about 70%, as
indicated by an arrow G.sub.2 of FIG. 15. FIG. 18 is a graph
showing a relationship between a film thickness and a position on
the processing target substrate W when the processing target
substrate W is processed by the plasma processing apparatus of FIG.
10 at a center/edge flow rate ratio of about 20%, as indicated by
an arrow G.sub.3 of FIG. 15. Vertical axes and horizontal axes on
the graphs depicted in FIGS. 16 to 18 are the same as those
depicted on the graphs of FIGS. 4 and 5, and redundant description
thereof will be omitted.
[0116] Referring to FIG. 15, when the center/edge flow rate ratio
is about 0%, a process non-uniformity is about (-) 33% and a
so-called center-fast distribution is shown. That is, as depicted
in FIG. 16, a center of the processing target substrate W is
greatly etched and a film thickness at the center is thin, whereas
an etching amount at an edge of the processing target substrate W
is reduced and a film thickness at the edge is thick. As the
center/edge flow rate ratio increases, the process non-uniformity
approaches 0%, and if the center/edge flow rate ratio finally
reaches about 70%, a so-called edge-fast distribution is shown.
That is, as illustrated in FIG. 17, the process non-uniformity
becomes about (+) 15%, and the edge of the processing target
substrate W may be more etched than the center thereof.
[0117] This result shows that the process non-uniformity can be
changed from the edge-fast distribution to the center-fast
distribution. On these graphs, it may be easy to adjust the process
non-uniformity to about 0% by varying the center/edge flow rate
ratio, i.e., by varying the gas supply amounts from the first and
second reactant gas supply units. On the graph shown in FIG. 15, a
process non-uniformity distribution as depicted in FIG. 18 may be
obtained by setting the center/edge flow rate ratio to about 20%.
In contrast, in the plasma processing apparatus shown in FIG. 21, a
graph may be shown on a position distanced away from 0%, and
maintained substantially parallel to a horizontal axis, and it
becomes very difficult to achieve a process non-uniformity of 0%
even if the center/edge flow rate ratio is adjusted.
[0118] Further, in this embodiment, although each supply hole is
described to have a circular shape, the present invention may not
be limited thereto, and the supply hole may have, by way of
example, an elongated shape, an oval shape or a polygonal shape.
Furthermore, a vertical position for forming the supply holes may
not be limited to the midway position, but the supply holes may be
formed at an upper portion or a lower portion of the ring-shaped
member 208 in a vertical direction. Moreover, an opening size of
each supply hole may be varied as required, and the number of the
supply holes is not limited to the mentioned example. By way of
example, 8 or 16 supply holes may be provided. In addition, the
cross section of the ring-shaped member may have a circular or
polygonal cross section.
[0119] Moreover, although this embodiment has been described for
the case that the second reactant gas supply unit includes the
first and second members and supported by the three supports, the
present invention may not be limited thereto, and the second
reactant gas supply unit for discharging the gas in the horizontal
direction may be embedded in a sidewall of the processing chamber,
as in the plasma processing apparatus shown in FIG. 9.
[0120] FIG. 19 is a schematic cross sectional view illustrating
major components of a plasma processing apparatus in such a case
and FIG. 19 corresponds to FIG. 1. In FIG. 19, the same parts as
those described in FIG. 1 will be assigned same reference numerals,
and redundant description thereof will be omitted.
[0121] Referring to FIG. 19, a plasma processing apparatus 221 may
include a second reactant gas supply unit 222 configured to supply
a reactant gas in a horizontal direction toward a center of a
processing target substrate W held on a holding table 14. A
temperature control unit 223 provided within the holding table 14
may include a first temperature controller 224 located at a center
of the holding table 14 in a diametric direction and a circular
ring-shaped second temperature controller 225 positioned outside
the first temperature controller 224.
[0122] A part of a sidewall 82 of a processing chamber 12 of the
plasma processing apparatus 221 is projected inward in a diametric
direction. This protrusion 229 is of a circular ring shape.
Further, gas supply holes 231 are opened through an inner surface
228 of the protrusion 229 in a horizontal direction. Further, a gas
flow path 230 extended from the outside of the processing chamber
12 to the supply holes 231 is provided within the sidewall 82. Each
supply hole 231 is opened in a circular shape and the supply holes
231 are arranged at a regular distance in a circumferential
direction. In addition, as in the plasma processing apparatus shown
in FIG. 10, temperature controllers 226 and 227 may be provided
within a lower part and an upper part of the sidewall 82 with the
gas flow path 230 located therebetween. With this configuration,
the same effects as described above can also be achieved.
[0123] Moreover, in the above-described embodiments, although the
second reactant gas supply unit of the plasma processing apparatus
is located at a position directly above the holding table but not
directly above the processing target substrate W, the present
invention may not be limited thereto, and the plasma processing
apparatus may be configured as follows.
[0124] That is, the plasma processing apparatus may include a
holding table configured to hold the processing target substrate
thereon; a processing chamber configured to perform therein a
plasma process on the processing target substrate, and having a
bottom positioned under the holding table and a ring-shaped
sidewall upwardly extending from a periphery of the bottom; a
plasma generator configured to generate plasma within the
processing chamber; and a reactant gas supply unit configured to
supply a reactant gas for the plasma process into the processing
chamber. Further, the reactant gas supply unit may include a first
reactant gas supply unit configured to supply the reactant gas in a
directly downward direction toward a central region of the
processing target substrate held on the holding table; and a second
reactant gas supply unit having a ring-shaped member provided at an
upper position of the holding table and at a position deviated from
a direct region of the processing target substrate held on the
holding table and at an inside position of the sidewall, and
configured to supply the reactant gas toward a center side of the
processing target substrate held on the holding table. FIG. 20
illustrates a. plasma processing apparatus 241 having a
configuration same as the configuration of the plasma processing
apparatus of FIG. 10 excepting that a ring-shaped member of a
second reactant gas supply unit 242 is provided at a position
deviated from a vertically upper region of a processing target
substrate W held on a holding table 14, i.e., at an outside
position from a vertically upper region of the holding table 14 and
an inside position from a sidewall 18. To elaborate, the
ring-shaped member is provided at a position outside from an edge
of the holding table 14. That is, the ring-shaped member may be
provided at an outside position from a vertically upper region of
the holding table 14. With this configuration, the same effects as
described above can also be achieved.
[0125] Further, in the plasma processing apparatuses shown in FIGS.
10, 19 and 20, the first and second temperature controllers are
provided within the holding table. However, the present invention
may not be limited thereto, and the first and second temperature
controllers may be provided at an outside of the holding table.
Moreover, the first and second temperature controllers may be
divided in a diametric direction, in a circumferential direction or
in a vertical direction. That is, each of the first and second
temperature controllers may be composed of a multiple number of
members. In addition, the first and second temperature controllers
may be formed as a single body. By way of example, a single-body
type heater capable of controlling temperatures of a center and an
edge independently may be used. Furthermore, the first and second
temperature controllers may not be provided, and the temperature
controllers provided in the sidewall and the like may also be
omitted. Further, it may be also possible to provide temperature
controllers in the plasma processing apparatus shown in FIG. 1 or
FIG. 9 if necessary.
[0126] In the above-described embodiments, although a wall surface
of the first reactant gas supply unit facing the holding table is
flat, the present invention may not be limited thereto, and a part
of the first reactant gas supply unit in which the supply holes are
provided may be protruded toward the holding table.
[0127] Further, in the above-described embodiments, although the
same kind of reactant gas is supplied from the first and second
reactant gas supply units, the kinds of gases from the first and
second reactant gas supply unit may be different.
[0128] Moreover, the second reactant gas supply unit may be
configured to supply the gas in a directly downward direction in
consideration of an apparatus configuration, particularly, in
consideration of dimensions of various components of the apparatus
such as a size of the processing chamber, a position of the holding
table, a size of the processing target substrate and so forth.
[0129] Furthermore, in the above-described embodiments, the plasma
processing apparatus is of a type that uses a microwave as a plasma
source, the present invention may not be limited thereto. By way of
example, the present invention may also be applicable to a plasma
processing apparatus using ICP (Inductively-Coupled Plasma), ECR
(Electron Cyclotron Resonance) plasma, parallel plate type plasma
or the like as a plasma source.
[0130] While various aspects and embodiments have been described
herein, other aspects and embodiments will be apparent to those
skilled in the art. The various aspects and embodiments disclosed
herein are for the purposes of illustration and are not intended to
be limiting. Therefore, the true scope and spirit of the invention
is indicated by the appended claims rather than by the foregoing
description, and it shall be understood that all modifications and
embodiments conceived from the meaning and scope of the claims and
their equivalents are included in the scope of the invention.
INDUSTRIAL APPLICABILITY
[0131] A plasma processing apparatus and a plasma processing method
in accordance with the present invention may be effectively used to
improve uniformity of a plasma process within a surface of a
processing target substrate.
[0132] [Explanation of Codes]
[0133] 11, 81, 91, 201, 221, 241: Plasma processing apparatus
[0134] 12, 87: Processing chamber
[0135] 13: Reactant gas supply unit
[0136] 14: Holding table
[0137] 15: Microwave generator
[0138] 16: Dielectric plate
[0139] 17: Bottom
[0140] 18, 22: Sidewall
[0141] 19: Gas exhaust hole
[0142] 20, 65: O-ring
[0143] 21: Matching unit
[0144] 22: Mode converter
[0145] 23: Waveguide
[0146] 24: Coaxial waveguide
[0147] 25: Central conductor
[0148] 26: External conductor
[0149] 27: Recess
[0150] 28: Wavelength shortening plate
[0151] 29: Slot hole
[0152] 30: Slot plate
[0153] 31,32: Cylindrical support
[0154] 33: Gas exhaust passageway
[0155] 34: Baffle plate
[0156] 35: Gas exhaust pipe
[0157] 36: Gas exhaust unit
[0158] 37: High frequency power supply
[0159] 38: Matching unit
[0160] 39: Power supply rod
[0161] 41: Electrostatic chuck
[0162] 42: Focus ring
[0163] 43: Electrode
[0164] 44, 45: Insulating film
[0165] 46: DC power supply
[0166] 47: Switch
[0167] 48: Coated line
[0168] 51: Coolant path
[0169] 52, 53: Pipe
[0170] 54: Gas supply pipe
[0171] 61: First reactant gas supply unit
[0172] 62, 92, 202, 222, 242: Second reactant gas supply unit
[0173] 63: Bottom surface
[0174] 64: Accommodation part
[0175] 66, 75, 85, 95, 215, 231: Supply hole
[0176] 67, 86, 88: Wall surface
[0177] 68, 89, 210, 230: Gas flow path
[0178] 69: Gas inlet
[0179] 70: Opening/closing valve
[0180] 71: Flow rate controller
[0181] 72: Gas supply system
[0182] 73, 84, 93, 208: Ring-shaped member
[0183] 74: Holding member
[0184] 76: End portion
[0185] 77: Top surface
[0186] 78: Center
[0187] 79a, 79b, 79c, 79d: Wall
[0188] 79e: Straight line
[0189] 80: Position
[0190] 83, 229: Protrusion
[0191] 94, 212a, 212b, 212c: Supporting member
[0192] 203, 204, 205, 206, 207, 223, 224, 225, 226, 227:
[0193] Temperature control unit
[0194] 209a: First member
[0195] 209b: Second member
[0196] 211a, 211b, 211c: Protrusion
[0197] 213a, 213b, 213c: Outer surface
[0198] 214a, 214b, 214c, 216, 228: Inner surface
[0199] 217: Cover
* * * * *