U.S. patent application number 09/758141 was filed with the patent office on 2001-07-19 for plasma etching system.
Invention is credited to Koguchi, Toshiaki, Shimizu, Hironari, Takahashi, Nobuyuki, Watanabe, Kazuhito.
Application Number | 20010008173 09/758141 |
Document ID | / |
Family ID | 18534972 |
Filed Date | 2001-07-19 |
United States Patent
Application |
20010008173 |
Kind Code |
A1 |
Watanabe, Kazuhito ; et
al. |
July 19, 2001 |
Plasma etching system
Abstract
A substrate holder and an electrode are arranged facing each
other in a vacuum chamber. The electrode is provided with a process
gas introduction mechanism and a gas blowoff plate. A substrate is
loaded on the substrate holder, the process gas is introduced, and
electric power is supplied between the substrate holder and the
electrode to generate plasma for etching the substrate surface. At
the rear side of the gas blowoff plate in the vacuum chamber, a
plurality of magnets is provided at concentric positions. The
magnetic field strength resulting from the magnets on the surface
of the substrate is made 0 Gauss. By using the magnets in this way
and improving the magnets, it is possible to establish a better
etching process for various materials to be etched.
Inventors: |
Watanabe, Kazuhito;
(Tama-shi, JP) ; Shimizu, Hironari;
(Tachikawa-shi, JP) ; Koguchi, Toshiaki;
(Kunitachi-shi, JP) ; Takahashi, Nobuyuki;
(Sagamihara-shi, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE
P.O. BOX 19928
ALEXANERIA
VA
22320
US
|
Family ID: |
18534972 |
Appl. No.: |
09/758141 |
Filed: |
January 12, 2001 |
Current U.S.
Class: |
156/345.46 |
Current CPC
Class: |
H01J 37/3244 20130101;
H01J 37/32623 20130101; H01J 37/3266 20130101 |
Class at
Publication: |
156/345 |
International
Class: |
H01L 021/3065 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 14, 2000 |
JP |
2000-006440 |
Claims
1. A plasma etching system comprising: a vacuum chamber, a
substrate holder arranged within said vacuum chamber, an electrode
arranged in said vacuum chamber so as to face said substrate
holder, having a process gas introduction mechanism and a gas
blowoff plate, and an electric power source for supplying electric
power to said electrode, wherein a substrate is loaded on said
substrate holder in said vacuum chamber of a vacuum state, the
process gas is introduced into said vacuum chamber through said
electrode, and said power source applies the electric power between
said substrate holder and said electrode to generate plasma used
for etching the surface of said substrate, further comprising; a
plurality of magnets arranged concentrically at a rear side of said
gas blowoff plate in said electrode within said vacuum chamber,
wherein the magnetic poles of the inner surfaces of said plurality
of magnets are arranged to alternate in polarity and the magnetic
field strength resulting from said plurality of magnets on the
surface of said substrate is substantially 0 Gauss.
2. A plasma etching system as set forth in claim 1, wherein the
magnetic field strength resulting from said plurality of magnets at
a plane positioned substantially at the center between said
substrate holder and said electrode is made a uniform 100
Gauss.
3. A plasma etching system as set forth in claim 1, wherein the
magnetic field strength resulting from said plurality of magnets at
a plane positioned substantially at the center between said
substrate holder and said electrode is made a uniform 200
Gauss.
4. A plasma etching system as set forth in claim 1, wherein said
plurality of magnets are fixed to a gas distribution plate and gas
introduction holes are formed in said gas distribution plate
corresponding to the intervals between the two of said plurality of
magnets.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a plasma etching system,
and more particularly, relates to a plasma etching system having
magnets in an electrode facing a substrate holder so as to control
the magnetic field strength in the space in front of the substrate
and thereby enabling various types of substrates to be etched and
improving the etch rate.
[0003] 2. Description of the Related Art
[0004] First an example of a plasma etching system of the related
art will be explained with reference to FIG. 6. The plasma etching
system is provided with a vacuum chamber 100. At the center of the
ceiling 101 of the vacuum chamber 100 a disk-shaped electrode 103
is arranged through a ring-shaped insulator 102. At the bottom 104
of the vacuum chamber 100 a substrate holder 106 is arranged on a
ring-shaped insulator 105. The electrode 103 and the substrate
holder 106 are placed facing each other in a parallel state. Each
of the electrode 103 and the substrate holder 106 has a built-in
known mechanism for controlling the temperature. Further, the
electrode 103 and the substrate holder 106 are connected to power
sources 107 and 108 respectively. Electric power for inducing the
discharge is supplied between the electrode 103 and the substrate
holder 106 by these power sources 107 and 108. An evacuation port
110 is provided at the surrounding side wall 109 of the vacuum
chamber 100. The evacuation port 110 has connected to it an
evacuating mechanism 112 through a pressure control valve 111. A
cylindrical shield member 113 is arranged at the inside of the
surrounding side wall 110 around the substrate holder 106. Plasma
is produced in the space inside the shield member 113. In the space
the plasma performs an etching process. The shield member 113 is
formed with several holes 113a. The inside and the outside of the
shield member 113 are connected through these holes. The shield
member 113 prevents contamination of the inner surface of the
vacuum chamber 100. The electrode 103 is provided with a gas
introduction mechanism for introducing process gas. The gas inlet
mechanism is comprised of a gas distribution plate 114 and a gas
blowoff plate 115. The gas introduction mechanism is connected to a
gas supply source (not shown) through a gas introduction pipe 116
from the side of the upper surface of the electrode 103. The gas
blowoff plate 115 has a large number of gas blowoff holes 115a. The
process gas is introduced in the space in front of the substrate
holder 106 through these gas blowoff holes. The member 117 provided
at the substrate holder 106 is a pushout rod for carrying the
substrates 118.
[0005] In the above configuration, a substrate 118 carried by a not
shown substrate carrying mechanism is loaded on the substrate
holder 106. Process gas is introduced into the vacuum chamber 100
through the gas introduction pipe 116. The process gas passes
through the gas distribution plate 115 and the gas blowoff plate
114 provided at the bottom side of the electrode 103 and is
introduced into the vacuum chamber 100. On the other hand, the
evacuating mechanism 112 evacuates the internal space 100A of the
vacuum chamber 100 to create a required vacuum state. The internal
pressure of the shield member 113 is controlled to a suitable
pressure by the pressure control valve 111. The internal pressure
of the shield member 113 is determined in accordance with the
process. Next, the electric power is fed between the substrate
holder 106 and the electrode 103 by the power sources 107 and 108
to cause a discharge in the space (space above substrate in
internal space 100A) in front of the substrate 106 to generate
plasma. This plasma is utilized for etching a material to be etched
on the substrate 118. At this time, the process gas introduced into
the inside region of the shield member 113 is equally blown off
over the substrate 118 by the gas distribution plate 114 and the
gas blowoff plate 115 provided in the vacuum at the electrode
103.
[0006] In the configuration of the plasma etching system of the
related art, the factors causing changes in the etch rate or
etching distribution of the etched material on the surface of the
substrate 118 are mainly the internal pressure of the vacuum
chamber, the process gas, the fed electric power, and other process
conditions. Therefore, conversely, when changing these process
conditions, it is possible to change the etch rate or etching
distribution of the etched material. Even if the process conditions
are changed so as to improve the etch rate or etching distribution
by a large extent, in practice, it is difficult to set process
conditions to achieve a major improvement. Further, by changing the
hardware configuration of a plasma etching system (for example,
expanding or reducing the discharge region by modification of the
shape of the shield member, or modification of the shape of the
substrate holder), it is possible to control the etch rate or
etching distribution of the etched material. In this case, however,
it is necessary to remodel the system by a large extent in
accordance with various processes. This becomes a large problem in
terms of costs and the trouble in work.
SUMMARY OF THE INVENTION
[0007] An object of the present invention is to provide a plasma
etching system which enables the establishment of a better etching
process for various etched materials by just the use of magnets and
further improvement of the magnets, enables various demands from
end users to be met, and enables improvement of the speed of
process development.
[0008] The plasma etching system according to the present invention
is configured as follows to achieve the above object.
[0009] The plasma etching system according to the present invention
has as a basic configuration a vacuum chamber functioning as a
plasma etching chamber and a substrate holder and an electrode
arranged facing each other in the inside of the vacuum chamber. A
substrate is loaded on the substrate holder. The electrode has a
mechanism for introducing a process gas and a gas blowoff plate.
The inside of the vacuum chamber is evacuated by an evacuating
mechanism and held at a predetermined reduced pressure state or
vacuum state. In the state with the substrate loaded on the
substrate holder, process gas is introduced inside the vacuum
chamber and power is fed between the substrate holder and the
electrode to generate plasma. This plasma etches the surface of the
substrate. In this configuration, further, a plurality of
ring-shaped magnets are arranged at concentric positions at the
inside of the vacuum chamber at the rear side of the gas blowoff
plate arranged at the electrode. These magnets are arranged so that
the poles at the inside surfaces alternate in polarity. The
magnetic field strength resulting from the plurality of magnets on
the surface of the substrate is made substantially 0 Gauss.
[0010] According to the above plasma etching system, the plasma is
controlled by providing magnets serving also as a gas distribution
plate right behind (or right in front of) the gas blowoff plate so
as to create a required distribution of magnetic field and magnetic
field strength at the region where the plasma is produced. Due to
this, it becomes possible to improve the distribution of the etched
material on the substrate and improve the etch rate. By making the
magnetic field strength near the surface of the substrate
substantially 0, the damage to the substrate is reduced.
[0011] In the above configuration, preferably, the magnetic field
strength resulting from the plurality of magnets at a plane
positioned substantially at the center of the substrate holder and
the electrode is made a uniform one of about 100 Gauss. By setting
the distribution of the magnetic field resulting from the magnets
to the value of the magnetic field strength explained above at the
above center position, the above effects are effectively
manifested.
[0012] In the plasma etching system having the above configuration,
preferably, the magnetic field strength resulting from the
plurality of magnets at the plane positioned substantially at the
center of the substrate holder and the electrode is made a uniform
one of about 200 Gauss. A similar effect can be exhibited even if
setting the value of the magnetic field strength at the above
center position at the above value.
[0013] In the plasma etching system having the above configuration,
preferably, a plurality of magnets are fixed to a gas distribution
plate and gas introduction holes are formed in the gas distribution
plate corresponding to the intervals between the two included in
the plurality of magnets. The gas distribution plate has a
plurality of gas introduction holes for introducing into the vacuum
chamber a process gas creating the etching gas. These gas
introduction holes are formed using the locations corresponding to
the spaces between the plurality of magnets since the plurality of
ring-shaped magnets are fixed to the gas distribution plate
arranged concentrically. Due to the actions of the plurality of
ring-shaped magnets arranged in the concentric positional
relationship and the gas distribution plate, a gas distribution
function causing distribution of the introduced gas is
realized.
[0014] In the plasma etching system according to the present
invention, since a plurality of ring-shaped magnets are provided
concentrically in a predetermined positional relationship at a
position right behind the gas blowoff plate positioned above the
substrate holder, the magnets are arranged so that their inside
polar surfaces become alternately S and N, and the magnets are set
so as to enable the magnetic field strength at the plane near the
substrate surface and the magnetic field strength at a plane at the
above center position to be set to predetermined values, the etch
rate and etching distribution of the etched material can be greatly
improved and the damage to the substrate can be minimized. Further,
since the spread of the discharge is suppressed, the power can be
concentrated and high efficiency and energy savings can be
realized.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] These and other objects and features of the present
invention will become clearer from the following description of the
preferred embodiments given with reference to the accompanying
drawings, in which:
[0016] FIG. 1 is a longitudinal sectional view of the schematic
basic configuration of a plasma etching system according to the
present invention;
[0017] FIG. 2 is a view of the gas distribution plate with magnets
fixed thereto as seen from below;
[0018] FIG. 3 is a sectional view along the line A-A in FIG. 2;
[0019] FIG. 4 is a view similar to FIG. 1 showing an example of the
specific design of the plasma etching system according to the
present invention;
[0020] FIG. 5 is a view of the distribution of the magnetic field
at a center position between the bottom surface of the gas blowoff
plate and the substrate loaded surface of the substrate holder for
a magnetic field created by the magnets, and the distribution of
the magnetic field near the surface of the substrate loaded on the
substrate holder; and
[0021] FIG. 6 is a longitudinal sectional view of the internal
structure of a representative example of a plasma etching system of
the related art.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] Hereinafter, preferred embodiments of the present invention
will be explained with reference to the attached drawings.
[0023] A representative embodiment of the plasma etching system
according to the present invention will be explained with reference
to FIG. 1 to FIG. 5. In FIG. 1, elements substantially the same as
elements explained relating to the related art are assigned
identical reference numerals.
[0024] The configuration of the plasma etching system shown in FIG.
1 to FIG. 3 will be explained in brief first. FIG. 1 to FIG. 3
shows a configuration highlighting the characteristic parts of the
present invention. The plasma etching system is provided with a
vacuum chamber 100, a disk-shaped electrode 103 arranged at the
center of a ceiling 101 of the vacuum chamber 100 through a
ring-shaped insulator 102, and a substrate holder 106 arranged at a
bottom 104 of the vacuum chamber 100 through a ring-shaped
insulator 105. The electrode 103 and the substrate holder 106 are
arranged facing each other in a parallel state. Each of them has a
well-known mechanism for controlling the temperature (not shown).
Further, the electrode 103 and the substrate holder 106 are
respectively connected to power sources 107 and 108. Electric power
for inducing the discharge is supplied into the region between the
electrode 103 and the substrate holder 106 by these power sources.
The electrode 103 and the substrate holder 106 function as a facing
electrode system. An evacuation port 110 is provided at the
surrounding side wall 109 of the vacuum chamber 100. The evacuation
port 110 has connected to it an evacuating mechanism 112 through a
pressure control valve 111. At the inside of the surrounding side
wall 110 around the substrate holder 106 is arranged a cylindrical
shield member 113. Plasma is produced in the space 100A inside the
shield member 113 for an etching process. The shield member 113 has
holes 113a which connect the inside and the outside of the shield
member. The shield member 113 prevents contamination of the inner
surface of the vacuum chamber 100. The electrode 103 is provided
with a gas introduction mechanism for introducing a process gas.
The gas introduction mechanism is comprised of a gas shower head
115. The gas inlet mechanism is connected to a gas supply source
(not shown) through a gas introduction pipe 116 from the side of
the upper surface of the electrode 103. The gas blowoff plate 115
has a large number of gas blowoff holes 115a. The process gas is
introduced in the space in front of the substrate holder 106
through these gas blowoff holes. A pushout rod 117 for pushing out
the substrate, which is used when loading the substrate 118, is
provided at the substrate holder 106.
[0025] This plasma etching system has the following characteristic
structure. The gas introduction mechanism is provided with a
plurality of ring-shaped magnets 11 to be arranged concentrically
in the vacuum region right behind the gas blowoff plate 115 (in the
location near the rear side of the gas blowoff plate 115). The
center magnet 11 is however cylindrical in shape. The plurality of
magnets 11 are arranged so that their N and S poles alternate at
the polar surfaces facing the bottom (or inside) in FIG. 1. In this
example, the lower magnetic polar surface of the cylindrical magnet
11 positioned at the center is for example the S pole, the lower
magnetic polar surface of the ring-shaped magnet 11 positioned at
the outside of the center magnet is the N pole. Further, the
magnetic polar surfaces of the ring-shaped magnets 11 outward from
there are alternately changed to be the S pole, N pole, S pole and
so on.
[0026] The plurality of magnets 11 are fixed to a gas distribution
plate 12 positioned above them. The gas distribution plate 12 is
attached to the bottom surface of the electrode 103 (the follow of
the electrode 103) in a state maintaining a constant distance from
the electrode 103. The gas distribution plate 12 is of a form which
can be divided into two positioned at the center and the periphery
for example. Reference numeral 12a shows the dividing line. In the
gas distribution plate 12, a large number of gas introduction holes
12b are formed at locations corresponding to the intervals between
the concentrically positioned magnets 11. The gas distribution
plate 12 provided with the magnets 11 also functions as an overall
gas distribution plate together with the magnets. As explained
above, the magnet 11 positioned at the center is not ring-shaped,
but a cylindrical block shape. However, it may also be a small
diameter ring shape. Further, the plurality of ring-shaped magnets
11 arranged concentrically are preferably equal in width in the
diametrical direction and arranged so that the intervals between
the adjoining two of the magnets 11 are equal. The dimensions,
however, are not limited to this. It is possible to set any
dimensions in accordance with the conditions of the system.
Further, as shown in FIG. 2, the ring-shaped magnets 11 have a
split structure in the circumferential direction. That is, the
ring-shaped magnets 11 are prepared by arranging substantially
box-shaped magnet segments in the circumferential direction.
Therefore, the ring-shaped magnets 11 shown in FIG. 2 have
polygonal shapes.
[0027] In FIG. 3, the polarities of the magnetic poles (inside
magnetic polar surfaces) facing the inside of the vacuum chamber in
the concentrically arranged ring-shaped magnets 11 are shown to be
opposite between adjoining magnets. In FIG. 3, the gas distribution
plate 12 is arranged at the right side. The left side direction is
the inside of the vacuum chamber 100. The magnets 11 are arranged
so that the N poles and S poles alternate at the left side magnetic
polar surfaces. In the illustrated example, the magnets are
arranged so that the center one becomes the N pole, the ring-shaped
magnet adjoining it at the outside becomes the S pole, and the ones
outward from there alternately become the N, S, N . . . poles. In
FIG. 1 and FIG. 3, magnets drawn in section by the first hatching
(rightward rising hatching) mean magnets with inside polar surfaces
of the S pole, while magnets drawn in section by the second
hatching (rightward falling hatching) mean magnets with inside
polar surfaces of the N pole. The directions of the hatching in the
sectional illustrations of the magnets differ between the S poles
and N poles. According to this arrangement of the magnets, as shown
in FIG. 1, magnetic field lines 13 are produced to be closed from a
magnet having an N polar surface to the magnets having S polar
surfaces at both sides (or one side) thereof. In the space between
the electrode 103 and the substrate holder 106 (space in front of
substrate 118) where the magnetic field as shown by the magnetic
field lines 13 is formed, by suitably setting the form of the
magnets 11 and their magnetic line force distribution, it is
becomes possible to produce a desired magnetic field and is further
possible to easily improve the magnetic field distribution or the
shape of the magnetic field in the space near the surface of the
substrate or the space in front of the substrate. The distribution
of the magnetic field will be explained in detail with reference to
FIG. 5 later.
[0028] FIG. 4 shows a specific example of the design of a plasma
etching system according to the present invention having the above
characteristic configuration. The basic configuration is the same
as the configuration shown in FIG. 1. In FIG. 4, elements
substantially the same as elements explained in FIG. 1 are assigned
the same reference numerals. The vacuum chamber 100 is provided
with a support 31 at the center of the bottom 104. The substrate
holder 106 is arranged on the support 31 through an insulating
support 32. The insulating support 32 corresponds to the
above-mentioned ring-shaped insulator 105. A temperature control
mechanism 33 is provided inside the substrate holder 106. A
substrate 118 is loaded on the top surface of the substrate holder
106. At the outside circumference of the substrate 118, ring-shaped
cover plates 34 and 35 are arranged. Above the substrate holder
106, at the ceiling 101 of the vacuum chamber 100, the electrode
103 is arranged through a ring-shaped insulator 102. Ring-shaped
intermediate members 36 and 37 are arranged between the ceiling 101
and the surrounding wall 109 of the vacuum chamber 100. The
electrode 103 is provided with a cooling passage 38 through which a
refrigerant flows for cooling the electrode 103. Note that
reference numeral 113 indicates the abovementioned shield member,
39 a power conductor connected to the electrode 103, and 40 a power
conductor connected to the substrate holder 106.
[0029] In the plasma etching system shown in FIG. 4, the above
specific configurations such as the gas blowoff plate, magnets, and
the gas distribution plate are not shown. A gas blowoff unit 41
includes magnets having the above configuration at the rear side of
the gas blowoff plate.
[0030] Next, FIG. 5 shows a representative example of the magnetic
field distribution (simulation based on experiments). The magnetic
field distribution shown in FIG. 5 was obtained by the experiments
based on the plasma etching system shown in FIG. 4. In the graph of
FIG. 5, the abscissa indicates the analysis position (mm). The
position of 0 on the left end corresponds to the center position of
the substrate 118. The ordinate indicates the magnetic field
strength (Gauss). The distribution curve 21 shows the magnetic
field distribution at the location 51 positioned at the substantial
center of the space between the electrode 103 and the substrate
holder 106. In this case, the distance between the electrode 103
and the substrate holder 106 is for example 34.5 mm as shown in
FIG. 4. As being clear from FIG. 5, the magnetic field strength is
a substantially uniform 0 Gauss or so (specifically 0.8 Gauss as an
average value obtained by the experiment) at a location near the
top surface of the substrate 118, while the magnetic field strength
at the location 51 positioned at the center is about 100 Gauss
(specifically 102 Gauss as an average value obtained by the
experiment). In both cases, the distributions can be said to be
relatively uniform in the radial direction.
[0031] The etching operation of the plasma etching system having
the above configuration will be explained next mainly referring to
FIG. 1. The carried substrate 118 is loaded on the substrate holder
106 through the well-known substrate carrying mechanism and a gate
valve (not shown). Process gas is introduced into the space 100A
inside the vacuum chamber 100 through the gas introduction pipe 116
and the distribution plate 12 and the gas blowoff plate 115 of the
electrode 103. On the other hand, the process gas is evacuated to
the outside by the evacuating mechanism 112. At this time, the
internal pressure of the shield member 113 is controlled to a
suitable pressure by the pressure control valve 111. In this state,
the electric power is fed between the substrate holder 106 and the
electrode 103 by the power sources 107 and 108 to cause the
discharge at the space 14 in front of the substrate 118 and produce
plasma. At this time, according to the plasma etching system of
this embodiment, the plasma produced at the space 14 in front of
the substrate 118 is controlled using the distribution and strength
of the magnetic field resulting from the magnets 11 arranged as
explained above. The material on the substrate 118 is etched using
the plasma produced in the space 14, but the state of the plasma is
controlled by the magnetic field based on the magnets 11, so it
becomes possible to etch the material on the substrate 118
uniformly in a short time. Further, in this embodiment, the process
gas introduced to the space 14 in front of the substrate 118 is
uniformly blown off over the substrate 118 by the holes of the gas
distribution plate 12, the intervals between the plurality of
magnets, and the gas blow-off holes 115a of the gas blowoff plate
115, which are provided in the vacuum at the electrode 103.
[0032] When supplying the electric power between the electrode 103
and the substrate holder 106 from the power sources 107 and 108 in
the state of introducing the process gas into the front space 14 of
the substrate 118 in the vacuum chamber 100, a discharge is induced
to generate plasma. When applying the electric power between the
substrate holder 106 and the electrode 103 facing thereto and
producing plasma at the internal space 100A, a plasma density and
plasma distribution determined by the electric field are obtained.
Due to this plasma density and plasma distribution, the etch rate
and the etching distribution of the etched material on the
substrate 118 are determined.
[0033] In the present embodiment, further, since the magnets 11
meeting the above conditions is used, the desired density and
distribution of plasma produced can be obtained by the correlation
of the electric field and magnetic field. Conversely, by applying
the magnetic field distribution of the magnets 11 to a certain set
electric field, it becomes possible to greatly improve the etch
rate and etching distribution of the etched material on the
substrate 118.
[0034] In the plasma etching system shown in FIG. 4, as another
experiment, when using the above magnets 11 creating, for example,
a 9 to 42 Gauss recessed magnetic field distribution at the plane
51 positioned at the center of the electrode 103 and the substrate
holder 106, an extremely recessed distribution shape is exhibited
and the average etch rate can be improved over 15 percent, as
compared with the projecting shape of the etching distribution of
the etched material when not using the magnets. By controlling the
magnetic field distribution at the plane 51 by the magnets 11 in
this way, it is possible to improve the distribution shape of the
etched material.
[0035] Further, in the plasma etching system, the damage given to
the substrate 118 is mentioned as a matter for concern, but since
the magnets 11 are arranged right behind the gas blowoff plate 115,
the distance between the substrate holder 106 and the electrode 103
is not made larger, it is possible to produce a strong magnetic
field near the gas blowoff plate 115, possible to produce a uniform
magnetic field substantially close to "0" on the surface of the
substrate 118, and possible to reduce the damage inflicted on the
surface of the substrate 118. Further, it becomes possible to move
the plasma away from near the substrate 118 and a synergistic
effect is produced relating to the reduction of the damage
inflicted on the substrate 118.
[0036] Further, by arranging the magnets 11 in rings, it is
possible to simplify the simulation, improve the speed of
development of such plasma etching systems, and therefore provide
timely systems to the end users. Further, by forming the magnets 11
divided in the circumferential direction, it becomes possible to
handle problems by just locally replacing parts.
[0037] While the invention has been described by reference to
specific embodiments chosen for purposes of illustration, it should
be apparent that numerous modifications could be made thereto by
those skilled in the art without departing from the basic concept
and scope of the invention.
* * * * *