U.S. patent application number 10/931132 was filed with the patent office on 2005-08-11 for plasma generating apparatus and plasma processing apparatus.
This patent application is currently assigned to Samsung Electronics Co., Ltd.. Invention is credited to Kim, Dae-il, Ma, Dong-joon, Navala, Sergiy Yakovlevich, Tolmachev, Yuri Nikolaevich.
Application Number | 20050173069 10/931132 |
Document ID | / |
Family ID | 34825119 |
Filed Date | 2005-08-11 |
United States Patent
Application |
20050173069 |
Kind Code |
A1 |
Tolmachev, Yuri Nikolaevich ;
et al. |
August 11, 2005 |
Plasma generating apparatus and plasma processing apparatus
Abstract
Provided is a microwave plasma generating apparatus using a
multiple open-ended cavity resonator, and a plasma processing
apparatus including the microwave plasma generating apparatus. The
plasma processing apparatus includes a container for forming a
process chamber, a support unit that supports a material to be
processed in the process chamber, a dielectric window formed on an
upper part of the process chamber, a gas supply unit that inject a
process gas into the process chamber, and a microwave supply unit
that includes a plurality of resonators for supplying microwaves
through the dielectric window.
Inventors: |
Tolmachev, Yuri Nikolaevich;
(Gyeonggi-do, KR) ; Ma, Dong-joon; (Gyeonggi-do,
KR) ; Kim, Dae-il; (Gyeonggi-do, KR) ; Navala,
Sergiy Yakovlevich; (Gyeonggi-do, KR) |
Correspondence
Address: |
BURNS DOANE SWECKER & MATHIS L L P
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
Samsung Electronics Co.,
Ltd.
Gyeonggi-do
KR
|
Family ID: |
34825119 |
Appl. No.: |
10/931132 |
Filed: |
September 1, 2004 |
Current U.S.
Class: |
156/345.36 |
Current CPC
Class: |
H01J 37/32247 20130101;
H01J 37/32192 20130101 |
Class at
Publication: |
156/345.36 |
International
Class: |
C23F 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 7, 2004 |
KR |
10-2004-0008174 |
Claims
What is claimed is:
1. A plasma processing apparatus comprising: a container for
forming a process chamber; a support unit that supports a material
to be processed in the process chamber; a dielectric window formed
on an upper part of the process chamber; a gas supply unit that
inject a process gas into the process chamber; and a microwave
supply unit that includes a plurality of open ended cavity
resonators for supplying microwaves through the dielectric
window.
2. The plasma processing apparatus of claim 1, wherein the gas
supply unit comprises: an upper gas supply unit mounted through the
center of the dielectric window; a first gas supply unit for
supplying the process gas to a surface of the material to be
processed at a predetermined angle; and a second gas supply unit
configured to have a radially uniform distribution of gas flux.
3. The plasma processing apparatus of claim 2, wherein gas flux
through each of the gas supply units is independently
controlled.
4. The plasma processing apparatus of claim 1, wherein the
plurality of open-ended cavity resonators are open at portions
contacting the dielectric window.
5. The plasma processing apparatus of claim 1, wherein the
microwave supply unit comprises: a microwave power source for
generating microwaves; a plurality of waveguides; a coupler for
distributing the microwaves generated by the microwave power source
to the plurality of waveguides; and a plurality of open ended
cavity resonators connected to a plurality of waveguides,
respectively.
6. The plasma processing apparatus of claim 5, wherein radial
plasma uniformity in the process chamber can be improved by
changing a ratio of microwave power transmitted to each of the
waveguides.
7. The plasma processing apparatus of claim 5, wherein each of the
waveguides are capable of rotation with respect to an axis of the
process chamber.
8. The plasma processing apparatus of claim 5, wherein the
plurality of waveguides are configured to be co-axial.
9. The plasma processing apparatus of claim 5, wherein adjacent
waveguides share a common wall.
10. The plasma processing apparatus of claim 1, wherein the
supporting means is able to move up and down to locate a substrate
loaded on the supporting means at a level of optimum plasma
uniformity.
11. A microwave supply unit comprising: a microwave power source
for generating microwaves; a plurality of waveguides; a coupler for
distributing the microwaves generated by the microwave power source
to the plurality of waveguides; and a plurality of resonators.
12. The microwave supply unit of claim 11, wherein the coupler
adjusts a ratio of microwave power transmitted to each of the
waveguides.
13. The microwave supply unit of claim 11, wherein the waveguides
are capable of rotation with respect to each other.
14. The microwave supply unit of claim 11, wherein portions of the
plurality of open-ended cavity resonators opposite to the
waveguides are open.
15. The microwave supply unit of claim 11, wherein the plurality of
waveguides are configured co-axially.
16. The microwave supply unit of claim 11, wherein adjacent
waveguides share a common wall.
Description
BACKGROUND OF THE INVENTION
[0001] This application claims the priority of Korean Patent
Application No. 2004-8174, filed on Feb. 7, 2004, in the Korean
Intellectual Property Office, the disclosure of which is
incorporated herein in its entirety by reference.
[0002] 1. Field of the Invention
[0003] The present invention relates to a semiconductor apparatus,
and more particularly, to an apparatus for generating microwave
plasma using a multiple open-ended cavity resonator and a plasma
processing apparatus using the multiple open-ended cavity
resonator.
[0004] 2. Description of the Related Art
[0005] Plasma is ionized gas with no macroscopic electric charge
due to an equal presence of positively charged ions and negatively
charged electrons. Plasma is generated at a very high temperature
and in a strong electric field or an RF electromagnetic field.
[0006] Plasma is generated by glow discharge when free electrons
excited by a direct current (DC) or an RF electric field collide
with gas molecules and generate active species such as ions,
radicals, or electrons. Conventionally, a plasma process involves
changing the characteristics of a material surface by physical
and/or chemical interaction between the material surface and an
obtained active species.
[0007] Currently, large area wafers are processed in the mass
production of semiconductor devices. In order to perform a plasma
process on a large-area wafer, a plasma processing apparatus must
be able to accommodate the large-area wafer and generate plasma
having uniform density. Such an apparatus is becoming increasingly
important in semiconductor device production.
[0008] Among plasma generating apparatuses, research into plasma
processing apparatuses using microwaves is currently in
progress.
[0009] FIG. 1 is a cross-sectional view of a conventional plasma
processing apparatus 10 using a bidirectional distributor.
[0010] The plasma processing apparatus 10 depicted in FIG. 1 is
disclosed in U.S. Pat. No. 6,497,783, dated Dec. 24, 2002, and
entitled "PLASMA PROCESSING APPARATUS PROVIDED WITH MICROWAVE
APPLICATOR HAVING ANNUNLAR WAVEGUIDE AND PROCESSING METHOD". The
plasma processing apparatus 10 includes a container 11 for forming
a processing chamber 19, a holding unit 12 that supports a wafer W
loaded in the processing chamber 19, a heater 25 coupled under the
holding unit 12, a gas supply unit 17 having a gas supply port 17a,
a dielectric window 14 mounted on an upper part of the processing
chamber 19 that isolates the processing chamber 19 from the outside
atmosphere, and a microwave supply unit 13 formed on the dielectric
window 14.
[0011] FIG. 2 is a perspective view of the microwave supply unit 13
of the conventional plasma processing apparatus 10 shown in FIG.
1.
[0012] Referring to FIGS. 1 and 2, the microwave supply unit 13 is
a resonator formed of a conductive material, includes a space 13a
through which microwaves propagate, upper and lower walls 13c and
13g, a plurality of slots 13b formed in the lower wall 13c adjacent
to the dielectric window 14, a side wall 13d, a microwave
introducing port 13e formed on the upper surface 13g, and a
distributor 13f for introducing microwaves supplied from a
waveguide 15 to the space 13a by dividing into two parts.
[0013] Referring to FIG. 1, the conventional plasma processing
apparatus 10 includes a microwave power source 6 having a microwave
oscillator such as a magnetron, at least two gas supply units, and
a gas exhaust system. Each of the gas supply units includes a gas
source 21, a valve 22, and a mass flow controller (MFC) 23. The gas
exhaust system includes an exhaust control valve 26, a cut-off
valve 25a, and a vacuum pump 24.
[0014] Plasma generation and processing in a conventional plasma
processing apparatus 10 is performed as follows.
[0015] A wafer W is loaded onto a holding unit 12 and heated to a
desired temperature. The processing chamber 19 is evacuated by the
vacuum pump 24 and a plasma process gas flows into the process
chamber 19 at a constant flow rate from the gas supply unit 17.
[0016] Next, power is applied to the microwave supply unit 13 from
the microwave power source 6 via the waveguide 15. Microwaves
supplied from the microwave supply unit 13 propagate into space 13a
after being divided into two parts by the distributor 13f. The
divided microwaves form standing waves by interfering with each
other in space 13a.
[0017] The microwaves are strengthened at the plurality of slots
13b, and propagate into the process chamber 19 via the plurality of
slots 13b and the dielectric window 14. An electric field of the
microwaves supplied to the process chamber 19 accelerates electrons
to generate high-density plasma at an upper part of the plasma
process chamber 19. The processing gas in the process chamber 19 is
then excited by the high density plasma to process a surface of the
wafer W loaded on the holding unit 12.
[0018] FIGS. 3a and 3b show a pattern of plasma formed by
microwaves radiated from the plurality of slots 13b of the
microwave supply unit 13, and a pattern of erosion corresponding to
the slots 13b, respectively, when performing a deposition process
using the conventional plasma processing apparatus 10.
[0019] Referring to FIGS. 3a and 3b, the conventional plasma
processing apparatus 10 has an additional device having a plurality
of slots A between a lower part of the microwave supply unit 13 and
the dielectric window 14 to improve the density uniformity of
plasma B. However, the additional device having the plurality of
slots A causes erosion of the dielectric window 14 and consequent
generation of unwanted particles. When performing a deposition of
etching process using the conventional plasma processing apparatus,
these unwanted particles, originating from erosion of the
dielectric window 14, become impurities in a deposited or etched
thin film.
SUMMARY OF THE INVENTION
[0020] The present invention provides a microwave plasma generating
apparatus that can form a high-density and uniform plasma source in
the vicinity of a material to be processed, and a plasma processing
apparatus.
[0021] The present invention also provides a microwave plasma
generating apparatus that can minimize power loss and avoid erosion
of a dielectric window, and a plasma processing apparatus.
[0022] According to an aspect of the present invention, there is
provided a plasma processing apparatus comprising a container for
forming a process chamber, a support unit that supports a material
to be processed in the process chamber, a dielectric window formed
on an upper part of the process chamber, a gas supply unit that
inject a process gas into the process chamber, and a microwave
supply unit that includes a plurality of open ended cavity
resonators for supplying microwaves through the dielectric
window.
[0023] According to another aspect of the present invention, there
is provided a microwave supply unit comprising a microwave power
source for generating microwaves, a plurality of waveguides, a
coupler for distributing the microwaves generated by the microwave
power source to the plurality of waveguides, and a plurality of
open ended cavity resonators.
[0024] According to another aspect of the present invention, when
processing a material in a process chamber using a plasma
processing apparatus having a microwave supply unit that includes a
process chamber and a plurality of open-ended cavity resonators,
uniform plasma density over the material can be maintained by
individually controlling power supplied to the plurality of
open-ended cavity resonators.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The above and other features and advantages of the present
invention will become more apparent by describing in detail
exemplary embodiments thereof with reference to the attached
drawings in which:
[0026] FIG. 1 is a cross-sectional view illustrating a conventional
plasma processing apparatus;
[0027] FIG. 2 is a perspective view of a microwave supply unit of
the conventional plasma processing apparatus shown in FIG. 1;
[0028] FIGS. 3a and 3b show a pattern of plasma formed by
microwaves radiated from a plurality of slots of the microwave
supply unit, and a pattern of erosion corresponding to the slots,
respectively, when performing a deposition process using the
conventional plasma processing apparatus shown in FIG. 1;
[0029] FIG. 4 is a cut-away perspective view of a plasma processing
apparatus according to an embodiment of the present invention;
[0030] FIG. 5 is a cross-sectional view of a microwave supply unit
of the plasma processing apparatus of FIG. 4;
[0031] FIG. 6 is a graph of plasma density versus distance from a
dielectric plate of the plasma processing apparatus of FIG. 4;
[0032] FIG. 7 is a schematic drawing illustrating a standing wave
formed by a single resonator in a process chamber of the plasma
processing apparatus of FIG. 4; and
[0033] FIG. 8 is a graph illustrating plasma density peaks
generated by each of a plurality of resonators in the process
chamber of the plasma processing apparatus of FIG. 4.
DETAILED DESCRIPTION OF THE INVENTION
[0034] The present invention will now be described more fully with
reference to the accompanying drawings in which a preferred
embodiment of the invention is shown. Like reference numerals refer
to like elements throughout the drawings.
[0035] FIG. 4 is a cut-away perspective view illustrating a plasma
processing apparatus according to an embodiment of the present
invention.
[0036] As depicted in FIG. 4, a plasma processing apparatus 100
according to an embodiment of the present invention comprises a
container 111 for forming a process chamber 109, a support unit 102
for supporting a substrate such as a wafer in the process chamber
109, a first gas supply unit 107 that includes a first gas inlet
port 107a, a second gas supply unit 117 that includes a second gas
inlet port 117a, a dielectric window 104 combined with an upper
part of the process chamber 109 that separates the process chamber
109 from the outer atmosphere, and a microwave supply unit 130
formed on the dielectric window 104.
[0037] FIG. 5 is a cross-sectional view of the microwave supply
unit 130 of the plasma processing apparatus 100 of FIG. 4.
[0038] The microwave supply unit 130 comprises a microwave power
source 132, a coupler 134, an upper gas supply unit 108 that
includes an upper gas inlet port 108a, a cooling water inlet port
136a, a cooling water outlet port 136b, first through n.sup.th
waveguides 103.sub.1 through 103.sub.n, and first through n.sup.th
resonators 113.sub.1 through 113.sub.n.
[0039] The microwave power source 132 of the microwave supply unit
130 includes a microwave generator such as a magnetron. The
microwaves generated by the microwave power source 132 are supplied
to the first through n.sup.th resonators 113.sub.1 through
113.sub.n through each of the first through n.sup.th waveguides
103.sub.1 through 103.sub.n by the coupler 134.
[0040] The first through n.sup.th resonators 113.sub.1 through
113.sub.n according to the present invention, as parts of a
multiple open-ended cavity resonator, have open-ends where they
connect to the first through n.sup.th waveguides 103.sub.1 through
103.sub.n and the dielectric window 104. Therefore, plasma
distribution in the process chamber 109 can be made uniform by
uniformly distributing microwaves over the entire surface of the
dielectric window 104.
[0041] Referring to FIG. 4, in the plasma processing apparatus 100
according to an embodiment of the present invention, the upper gas
supply unit 108 performs two functions. The first function is
supplying cleaning gas for cleaning the process chamber 109 after
depositing or etching a thin film on a substrate loaded on the
support unit 102. For example, C.sub.2F.sub.6 gas may be supplied
for cleaning the process chamber 109 after depositing a SiO.sub.2
thin film. The other function is mechanically supporting a center
portion of the dielectric window 104.
[0042] By mechanically supporting the center portion of the
dielectric window 104, a large and relatively thin dielectric
window 104 can be supported with reduced mechanical stress.
[0043] For uniform distribution of a process gas supplied to the
substrate, a plasma source housing 107f includes the first gas
supply unit 107 that includes the first gas inlet port 107a for
injecting the process gas at a predetermined angle to a surface of
the substrate. The second gas supply unit 117 including the second
gas inlet port 117a is located under the plasma source housing 107f
and is structured to provide a uniform distribution of gas flux in
all azimuthally. Gas flux through each of the gas inlet ports
described above can be controlled independently. Therefore, the
distribution of the process gas supplied to the substrate can be
made uniform.
[0044] A direct cooling system for cooling the dielectric window
104 is employed. That is, cooling water entering through the
cooling water inlet port 136a directly contacts the dielectric
window 104 and is discharged through the cooling water outlet port
136b to the outside after reducing a temperature gradient in the
radial direction of the dielectric window 104.
[0045] The plasma processing apparatus 100 depicted in FIG. 4 uses
a pair of co-axial type resonators, i.e., first and second
resonators 113.sub.1 and 113.sub.2, for exciting the microwave
plasma in the process chamber 109. The second resonator 113.sub.2
is located near an edge of the dielectric window 104. The second
resonator 113.sub.2 is a bottom open-ended cavity resonator, and
functions to generate very high-density plasma near the edge of the
process chamber 109.
[0046] The microwave power generated by the microwave power source
132 enters the first and second waveguides 103.sub.1 and 103.sub.2
through the coupler 134. Each of the microwaves entering the first
and second waveguides 103.sub.1 and 103.sub.2 enters each of the
first and second resonators 113.sub.1 and 113.sub.2 via tapered
waveguide units 105.sub.1 and 105.sub.2 connected to each of the
waveguides 103.sub.1 and 103.sub.2.
[0047] An amount of microwave power generated by the microwave
power source 132 and entering into the first and second resonators
113.sub.1 and 113.sub.2 can be controlled by first and second
combining probes 112a and 112 b included in the first and second
waveguides 103.sub.1 and 103.sub.2.
[0048] Controlling the microwave entering into the first resonator
113.sub.1 can control density of microwave plasma at the center
portion of the process chamber 109. For example, changing a ratio
of microwave power transmitted to the second waveguide 103.sub.2
can control plasma uniformity in the radial direction in the
process chamber 109.
[0049] The plasma processing apparatus 100 depicted in FIG. 4 uses
a microwave plasma generating device composed of the first and
second resonators 113.sub.1 and 113.sub.2. However, a plasma
processing apparatus according to alternative embodiments of the
present invention may use a microwave plasma generating device
composed of any number of resonators.
[0050] In the case of a plasma processing apparatus according to an
alternative embodiment of the present invention that uses a
microwave plasma generating device employing n resonators, plasma
uniformity in the vicinity of the dielectric window 104 in the
process chamber 109 can be controlled by controlling a ratio of
microwave power entering each of the resonators by controlling the
coupler 134.
[0051] Also, although not shown, employing an individual microwave
power source in each of the waveguides can control plasma
uniformity.
[0052] The first and second movable flanges 115a and 115b are used
for matching each of the waveguides to the corresponding microwave
power sources.
[0053] Also, the first waveguide 103.sub.1 can be rotated with
respect to an axis of the process chamber 109, and the second
waveguide 103.sub.2 can be structured to rotate with respect to the
first waveguide 113.sub.1. Accordingly, the microwave plasma
generating device can be easily combined with the plasma processing
apparatus.
[0054] The support unit 102 is located under the process chamber
109 and can move up and down to place the substrate loaded on the
support unit 102 at a level at which plasma uniformity is
optimum.
[0055] According to the present invention, the plurality of
microwave waveguides is co-axial and adjacent microwave waveguides
share a wall.
[0056] FIG. 6 is a graph of plasma density versus distance from the
dielectric window 104 toward a wafer substrate W mounted on the
support unit 102 of the plasma processing apparatus of FIG. 4.
[0057] Referring to FIG. 6, d.sub.2 represents optimum uniformity
of plasma in the radial direction of the substrate W, and d.sub.1
and d.sub.3 represent less favorable plasma distributions. Since
the wafer substrate W can be located at an optimum distribution
region of plasma by adjusting a distance between the dielectric
window 104 and the wafer substrate W, it is not necessary to create
uniform plasma in the whole volume of process chamber 109 in order
to get uniform flux on the substrate W. It is sufficient to control
the individual plasma density peaks generated by the plurality of
resonators 113.sub.1 through 113.sub.n in the process chamber
109.
[0058] FIG. 7 is a schematic drawing illustrating a standing wave
formed by a single resonator in the process chamber 109.
[0059] Referring to FIG. 7, a standing wave has a peak at a
location corresponding to a center line off the resonator. The
amplitude of the standing wave indicates the magnitude of microwave
power, and the plasma density in the process chamber 109 varies
according to the microwave power.
[0060] FIG. 8 is a graph illustrating plasma density peaks
generated by each of the plurality of resonators 113.sub.1 through
113.sub.n in the process chamber 109. For simplicity, the cooling
water inlet port 136a and the cooling water outlet port 136b are
omitted.
[0061] Referring to FIG. 8, a center peak 0 at the center of the
process chamber 109 is formed by the first resonator 113.sub.1.
Peaks 0.sub.2 through 0.sub.n are formed at locations corresponding
to center lines of the second through the nth resonators 113.sub.2
through 113.sub.n. Since all of the resonators are symmetrical with
respect to the center of the process chamber 109, the peaks also
have azimuthal symmetry. Accordingly, a top view of the peaks is a
concentric circle.
[0062] The resonators are arranged to form the peaks
0.sub.2-0.sub.n at a predetermined distance from the center peak 0.
Thus, as described above, the plasma density is varied according to
distance from the dielectric window 104 in the process chamber 109,
as depicted in FIG. 6. Therefore, according to the present
invention, uniform plasma density in the radial direction at a
predetermined distance from the dielectric window 104 can be
obtained even if the plasma density is not uniform throughout the
entire process chamber 109.
[0063] In order to form peaks at locations corresponding to the
center lines of the resonators, resonance must occur in each of the
resonators. A resonance condition of each of the resonators
according to the present invention is that the perimeter of
resonator center line must be equal to integer number of
wavelengths of the microwave for waveguide corresponding to the
resonator. At this time, it should be noted that, in the case of an
open-type waveguide, the wavelength is not the same as in the case
of a closed-type waveguide with conductive walls on all sides. This
is because, in the open-type waveguide, not only a bent upper ring
constituting the waveguide but also the dielectric window and the
process chamber together form a resonator.
[0064] Even though an oscillation frequency in the resonator is
determined by the frequency input from the microwave supply unit,
the types of mode excited in each resonator also depend on location
of coupling device. As far as the coupling occurs through a number
of independent ports, each of input microwaves will excite its own
resonance mode at same frequency.
[0065] Changing a ratio of microwave power transmitted to the
corresponding resonator can control the amplitude of a peak at a
given radial position. As depicted in FIG. 5, the microwave supply
unit according to the present invention enables the use of three or
more co-axial resonators at different radial distances from the
center, and this is important for enabling uniform plasma
processing over a large region.
[0066] While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those of ordinary skill in the art that various
changes in form and details may be made therein without departing
from the spirit and scope of the present invention as defined by
the following claims.
[0067] As described above, due to the structure of the plasma
processing apparatus according to the present invention, plasma can
be formed with a uniform distribution over a large substrate using
a plurality of ring-type open-ended cavity resonators.
[0068] Also, erosion of a dielectric window can be avoided since
the plasma processing apparatus according to the present invention
does not use a plurality of slots for supplying microwaves through
the dielectric window.
[0069] Also, a process gas can be ionized and decomposed
effectively by supplying the process gas to locations close to the
dielectric window.
* * * * *