U.S. patent application number 12/872980 was filed with the patent office on 2011-05-05 for multi-peripheral ring arrangement for performing plasma confinement.
Invention is credited to Rajinder Dhindsa, Akira Koshishi, Alexei Maraktanov.
Application Number | 20110100553 12/872980 |
Document ID | / |
Family ID | 43628709 |
Filed Date | 2011-05-05 |
United States Patent
Application |
20110100553 |
Kind Code |
A1 |
Dhindsa; Rajinder ; et
al. |
May 5, 2011 |
MULTI-PERIPHERAL RING ARRANGEMENT FOR PERFORMING PLASMA
CONFINEMENT
Abstract
An arrangement for performing plasma confinement within a
processing chamber during substrate processing is provided. The
arrangement includes a first peripheral ring positioned next to a
secondary peripheral ring. The first peripheral ring surrounds a
confined chamber volume that sustains plasma for etching a
substrate. The first peripheral ring includes a first plurality of
slots for exhausting processed byproduct gas from the confined
chamber volume. The second peripheral ring includes a second
plurality of slots that is positioned next to the first plurality
of slots such that the second plurality of slots does not overlap
the first plurality of slots, thereby preventing a direct
line-of-sight from within the confined chamber volume to an outside
chamber volume (an area outside of the first peripheral ring). The
arrangement also includes a manifold connecting the two rings to
provide a route for exhausting the processed byproduct gas from the
confined chamber volume.
Inventors: |
Dhindsa; Rajinder; (San
Jose, CA) ; Koshishi; Akira; (Fremont, CA) ;
Maraktanov; Alexei; (Fremont, CA) |
Family ID: |
43628709 |
Appl. No.: |
12/872980 |
Filed: |
August 31, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61238656 |
Aug 31, 2009 |
|
|
|
61238665 |
Aug 31, 2009 |
|
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Current U.S.
Class: |
156/345.26 ;
156/345.1; 156/345.43; 156/345.48 |
Current CPC
Class: |
H01J 37/32623 20130101;
H01J 37/32642 20130101 |
Class at
Publication: |
156/345.26 ;
156/345.1; 156/345.48; 156/345.43 |
International
Class: |
C23F 1/08 20060101
C23F001/08; H01L 21/02 20060101 H01L021/02 |
Claims
1. An arrangement for performing plasma confinement within a
processing chamber of a plasma processing system during processing
of a substrate, comprising: a first peripheral ring configured at
least for surrounding a confined chamber volume, wherein said
confined chamber volume is configured for sustaining a plasma for
etching said substrate during substrate processing, said first
peripheral ring including a first plurality of slots, wherein said
first plurality of slots is configured at least for exhausting
processed byproduct gas from said confined chamber volume during
said substrate processing; a second peripheral ring, wherein said
second peripheral ring is positioned next to said first peripheral
ring, said second peripheral ring includes a second plurality of
slots, wherein a first slot of said second plurality of slots is
positioned next to a first slot of said first plurality of slots
such that said first slot of said second plurality of slots does
not overlap said first slot of said first plurality of slots,
thereby preventing a direct line-of-sight from within said confined
chamber volume to an outside chamber volume, wherein said outside
chamber volume is an area outside of said first peripheral ring;
and a manifold connecting said first peripheral ring to said second
peripheral ring, wherein said manifold is configured at least for
providing a route for said processed byproduct gas to be exhausted
from said confined chamber volume.
2. The arrangement of claim 1 further including a power source
coupled to said second peripheral ring, wherein said power source
is configured at least to create a charge on said second peripheral
ring to deflect electrons from flowing back into said confined
chamber volume.
3. The arrangement of claim 2 wherein said power source is a radio
frequency power source.
4. The arrangement of claim 2 wherein said power source is a direct
current power source.
5. The arrangement of claim 1 wherein said first peripheral ring is
made from a material that includes a dielectric material.
6. The arrangement of claim 1 wherein said first peripheral ring is
made from a material that includes a semi-conductor material.
7. The arrangement of claim 1 wherein said second peripheral ring
is made from a material that includes a dielectric material.
8. The arrangement of claim 1 wherein said first peripheral ring is
made from a material that includes a conductive material.
9. The arrangement of claim 1 wherein said plasma processing system
is a capactively-coupled plasma processing system.
10. An arrangement for performing pressure control within a
processing chamber of a plasma processing system during processing
of a substrate, comprising: a multi-peripheral ring arrangement for
performing said plasma confinement, wherein said multi-peripheral
ring arrangement includes at least a first peripheral ring
configured at least for surrounding a confined chamber volume,
wherein said confined chamber volume is configured for sustaining a
plasma for etching said substrate during substrate processing, said
first peripheral ring including a first plurality of slots, wherein
said first plurality of slots is configured at least for exhausting
processed byproduct gas from said confined chamber volume during
said substrate processing, a second peripheral ring, wherein said
second peripheral ring is positioned next to said first peripheral
ring, said second peripheral ring includes a second plurality of
slots, wherein a first slot of said second plurality of slots is
positioned next to a first slot of said first plurality of slots
such that said first slot of said second plurality of slots does
not overlap said first slot of said first plurality of slots,
thereby preventing a direct line-of-sight from within said confined
chamber volume to an outside chamber volume, wherein said outside
chamber volume is an area outside of said first peripheral ring,
and a manifold connecting said first peripheral ring to said second
peripheral ring, wherein said manifold is configured at least for
providing a route for said processed byproduct gas to be exhausted
from said confined chamber volume; and a conductive control ring,
wherein said conductive control ring is positioned next to said
multi-peripheral ring arrangement and is configured to include a
third plurality of slots, wherein said pressure control is achieved
by moving said conductive control ring relative to said
multi-peripheral ring arrangement such that a first slot of said
second plurality of slots of said multiple ring arrangement is
offset relative to a second slot of said third plurality of slots
of said conductive control ring, wherein said offset is from a
range of zero offset to full offset.
11. The arrangement of claim 10 further including a motor, wherein
said motor is configured to move said conductive control ring to
perform said pressure control.
12. The arrangement of claim 11 further including a set of sensors
configured for collecting processing data about pressure volume
within said confined chamber volume.
13. The arrangement of claim 12 further including a control module
configured for at least receiving said processing data from said
set of sensors, analyzing said processing data, determining a new
position for said conductive control ring, and sending said new
position as a set of instructions to said motor.
14. The arrangement of claim 13 wherein said motor is configured to
receive said set of instructions and to move said conductive
control ring to adjust said pressure volume within said confined
chamber volume.
15. The arrangement of claim 14 wherein said conductive control
ring is positioned outside of said confined chamber volume, wherein
said multi-peripheral ring arrangement is nested inside said
conductive control ring such that said conductive control ring
surrounds said multi-peripheral ring arrangement.
16. The arrangement of claim 15 wherein said conductive control
ring is made from a dielectric material.
17. The arrangement of claim 10 wherein said plasma processing
system is a capactively-coupled plasma processing system.
18. The arrangement of claim 10 further including a power source
coupled to said second peripheral ring, wherein said power source
is configured at least to create a charge on said second peripheral
ring to deflect a set of electrons flowing back into said confined
chamber volume.
19. The arrangement of claim 18 wherein said power source is a
radio frequency power source.
20. The arrangement of claim 18 wherein said power source is a
direct current power source.
Description
PRIORITY CLAIM
[0001] This application is related to and claims priority under 35
U.S.C. .sctn.119(e) to a commonly assigned provisional patent
application entitled "A Multiple Peripheral Ring Arrangement for
Performing Plasma Confinement," by Dhindsa et al., Attorney Docket
Number P1989P/LMRX-P184P1, Application Ser. No. 61/238,656, filed
on Aug. 31, 2009, which is incorporated by reference herein.
CROSS REFERENCE TO RELATED APPLICATIONS
[0002] The present invention is related to the following
applications, all of which are incorporated herein by
reference:
[0003] Commonly assigned application entitled "A Local Plasma
Confinement and Pressure Control Arrangement and Methods Thereof,"
filed on even date herewith by Dhindsa et al. herein (Attorney
Docket Number P1990/LMRX-P185), which claims priority under 35
U.S.C. .sctn.119(e) to a commonly assigned provisional patent
application entitled "A Local Plasma Confinement and Pressure
Control Arrangement and Methods Thereof," by Dhindsa et al.,
Attorney Docket Number P1990P/LMRX-P185P1, Application Ser. No.
61/238,665, filed on Aug. 31, 2009, which is incorporated by
reference herein.
BACKGROUND OF THE INVENTION
[0004] Advances in plasma processing have provided for the growth
in the semiconductor industry. With the utilization of a plasma
processing system, substrates may be transformed into a variety of
devices, such as a micro electro-mechanical system (MEMS) device.
To gain a competitive advantage, a manufacturing company needs to
be able to maintain tight control of the process parameters in
order to minimize waste and produce high quality semiconductor
devices.
[0005] To facilitate discussion, FIG. 1 shows a simple diagram of a
partial view of a processing chamber 100 with a peripheral ring
arrangement. Consider the situation wherein, for example, a
substrate 106 is being processed within processing chamber 100.
Substrate 106 may be positioned above a bottom electrode 104.
Within processing chamber 100, gas may interact with radio
frequency (RF) current to form plasma 108 between substrate 106 and
an upper electrode 102 during substrate processing. RF current may
be flowing from an RF source 122 through a cable 124 and a RF match
120 to enter processing chamber 100.
[0006] In order to control plasma formation and to protect the
process chamber walls, plasma 108 may be confined to a limited
chamber volume 110, such as the region surrounded by a peripheral
ring 112. In addition to peripheral ring 112, the periphery of
confined chamber volume 110 may also be defined by upper electrode
102, bottom electrode 104, an edge ring 114, insulator rings 116
and 118, and a chamber support structure 128.
[0007] In order to exhaust the gas (such as the neutral species of
the gas) from the confinement region (confined chamber volume 110),
peripheral ring 112 may include a plurality of slots (such as slots
126a, 126b, and 126c). Each slot has a fixed geometry and is
configured to be large enough to allow the processed byproduct gas
(such as neutral gas species) to exit confined chamber volume 110.
In other words, the processed byproduct gas (such as neutral gas
species) may traverse from confined chamber volume 110 through the
slots into an external region 132 (outside chamber volume) of
processing chamber 100 before being pumped out of processing
chamber 100 via a turbo pump 134.
[0008] Since the slots provide a direct line-of-sight from within
confined chamber volume 110 and external region 132 of processing
chamber 100, the RF current may leak through and establish a
presence in external region 132 of processing chamber 100. Under
certain conditions, the presence of a RF field may cause the
processed byproduct gas (such as neutral gas species) (which has
been exhausted from confined chamber volume 110 into external
region 132 of processing chamber 100) to react and ignite a plasma
142 in the outside chamber volume.
[0009] The possibility of a plasma forming environment in external
region 132 of processing chamber 100 is highly likely if a high
pressure volume/level exists within processing chamber 100. In an
example, during substrate processing, the pressure volume/level may
have fallen below an acceptable threshold range (such as that
established by a recipe step). To increase the pressure
volume/level within confined chamber volume 110, a vacuum valve 138
may be tightened. Unfortunately, the adjustment of vacuum valve 138
may not only increase the pressure volume/level within confined
chamber volume 110 but also may increase the pressure volume/level
in external region 132 of processing chamber 100. Thus, in this
type of environment (such as a high-pressurized environment), the
presence of a RF field may cause the processed byproduct gas (such
as neutral gas species) to react and ignite plasma 142 in a region
outside of confined chamber volume 110.
[0010] Accordingly, an arrangement for performing plasma
confinement is desirable.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0011] The present invention is illustrated by way of example, and
not by way of limitation, in the figures of the accompanying
drawings and in which like reference numerals refer to similar
elements and in which:
[0012] FIG. 1 shows a simple diagram of a partial view of a
processing chamber 100 with a peripheral ring arrangement.
[0013] FIGS. 2A, 2B, 2C, and 2D show, in embodiments of the
invention, simple diagrams illustrating a multi-peripheral ring
arrangement for performing plasma confinement within a processing
chamber.
[0014] FIG. 3 shows, in an embodiment of the invention, a
processing chamber environment with a multi-peripheral ring
arrangement with a conductive control ring for performing pressure
control and plasma confinement.
DETAILED DESCRIPTION OF EMBODIMENTS
[0015] The present invention will now be described in detail with
reference to a few embodiments thereof as illustrated in the
accompanying drawings. In the following description, numerous
specific details are set forth in order to provide a thorough
understanding of the present invention. It will be apparent,
however, to one skilled in the art, that the present invention may
be practiced without some or all of these specific details. In
other instances, well known process steps and/or structures have
not been described in detail in order to not unnecessarily obscure
the present invention.
[0016] Various embodiments are described hereinbelow, including
methods and techniques. It should be kept in mind that the
invention might also cover articles of manufacture that includes a
computer readable medium on which computer-readable instructions
for carrying out embodiments of the inventive technique are stored.
The computer readable medium may include, for example,
semiconductor, magnetic, opto-magnetic, optical, or other forms of
computer readable medium for storing computer readable code.
Further, the invention may also cover apparatuses for practicing
embodiments of the invention. Such apparatus may include circuits,
dedicated and/or programmable, to carry out tasks pertaining to
embodiments of the invention. Examples of such apparatus include a
general-purpose computer and/or a dedicated computing device when
appropriately programmed and may include a combination of a
computer/computing device and dedicated/programmable circuits
adapted for the various tasks pertaining to embodiments of the
invention.
[0017] As aforementioned in the background section, the RF current
(RF field) may leak out of the confinement region (region
surrounded by the peripheral ring). Given the right pressure
environment, the RF current may ignite the processed byproduct gas
(such as neutral gas species) to form unconfined plasma (i.e.,
plasma outside of the confinement region). Since unconfined plasma
may narrow the process window and may also damage the processing
chamber wall, an arrangement is needed to minimize the possibility
of RF field leakage.
[0018] In one aspect of the invention, the inventors herein
realized that by removing the direct line-of-sight from the
confinement region to the outside chamber volume, RF field leakage
may be substantially eliminated. In accordance with embodiments of
the present invention, an arrangement for plasma confinement is
provided. Embodiments of the invention include a multi-peripheral
ring arrangement for managing the RF field.
[0019] In an embodiment of the invention, a multi-peripheral ring
arrangement is provided for performing plasma confinement within a
processing chamber of a plasma processing system. In an embodiment,
the multi-peripheral ring arrangement may be implemented within a
capacitively-coupled plasma (CCP) processing system.
[0020] In an embodiment of the invention, the multi-peripheral ring
arrangement may include a first peripheral ring next to a second
peripheral ring. As discussed herein, the term "next to" may refer
to but are not limited to the rings having a nesting arrangement
(such as the rings being nested inside and out, the rings being
nested within one another), being stacked on top of one another,
being adjacent to one another, being separated by a small gap, and
the like. In a preferred embodiment, the multi-peripheral ring
arrangement may include a first peripheral ring stacked on top of a
second peripheral ring. The first peripheral ring may be made of a
dielectric material or a semi-conductor material. Similarly, the
second peripheral ring may be made from a dielectric material. The
second peripheral ring may also be made from a conductive material
such as stainless steel.
[0021] Each peripheral ring may have a plurality of slots, which
may be employed to exhaust the processed byproduct gas (such as
neutral gas species) from the confinement region. As discussed
herein, the term "processed byproduct gas" refers to any gas
species that is a byproduct of the processing and need to be
exhausted. In an embodiment, each slot has a radial geometry.
However, the slots are not limited to a radial shape and may have
other configurations, including a peripheral geometry.
[0022] In one embodiment, the number/shape/size of the slots may
have the same geometry and dimension on both peripheral rings. In
another embodiment, the number/shape/size of the slots on the first
peripheral ring may differ from the slots on the secondary
peripheral ring. In an example, the shape of the slots on the
primary peripheral ring may have a radial geometry while the slots
of the secondary ring may have a peripheral geometry. Additionally
or alternatively, the slot size may differ between the two
peripheral rings. In an example, the slot size of the primary
peripheral ring may be larger than the slot size of the secondary
peripheral ring. Likewise, the slot size of the secondary
peripheral ring may be larger than the slot size of the primary
peripheral ring. Regardless, the slots of the secondary peripheral
ring are offset away from the slots of the primary peripheral ring
to prevent a direct line-of-sight from the confinement region to
the outside chamber volume, in an embodiment. Without a direct
line-of-sight, the RF current is substantially blocked from
escaping the confinement region. Accordingly, without the presence
of an RF field in the external region of the processing chamber,
conditions in the outside chamber volume are usually not capable of
supporting plasma formation.
[0023] FIG. 2A shows; in an embodiment of the invention, a simple
diagram of a partial view of a processing chamber 200 with a
multi-peripheral ring arrangement for performing plasma
confinement. Consider the situation wherein, for example, a
substrate 206 is being processed within processing chamber 200. In
an embodiment, processing chamber 200 may be a capacitively-coupled
plasma processing chamber. Substrate 206 may be positioned above a
bottom electrode 204. During substrate processing, a plasma 208,
which may be employed to etch substrate 206, may form between
substrate 206 and an upper electrode 202.
[0024] In order to control plasma formation and to protect the
processing chamber walls, a primary peripheral ring 212 may be
employed. Primary peripheral ring 212 may be made from a dielectric
material or a semi-conductor material. Usually, primary peripheral
ring 212 may be configured to surround the periphery of a confined
chamber volume 210 in which plasma 208 is to form. In addition to
peripheral ring 212, the periphery of confined chamber volume 210
may also be defined by upper electrode 202, bottom electrode 204,
an edge ring 214, insulator rings 216 and 218, and chamber support
structure 228.
[0025] During substrate processing, gas may flow from a gas
distribution system (not shown) into confined chamber volume 210
and interact with RF current to create plasma 208. RF current may
be flowing From an RF source 222 through a cable 224 to a RF match
220. From RF match 224, the RF current may flow through bottom
electrode 204 and be available within confined chamber volume 210
for plasma formation. Those skilled in the art are aware that some
of the chamber components (such as the upper electrode, the bottom
electrode, the insulator rings, the edge ring, the chamber support
structure, and the like) may have other configurations than that
shown. Also, the number of RF sources and RF matches may also vary
depending upon the plasma processing system.
[0026] In order to exhaust the processed byproduct gas (such as
neutral gas species) from the confinement region (confined chamber
volume 210), primary peripheral ring 212 may include a plurality of
slots (such as slots 226a, 226b, 226c, and 226d). The processed
byproduct gas (such as neutral gas species) may traverse from
confined chamber volume 210 into an external region 232 (outside
chamber volume) of processing chamber 200 before being pumped out
of processing chamber 200 via a turbo pump 234.
[0027] The slots on primary peripheral ring 212 may have a radial
shape, although other configurations may be employed. Each slot has
a fixed geometry and is configured to be sufficiently large to
allow the processed byproduct gas (such as neutral gas species) to
exit confined chamber volume 210. As aforementioned, each slot
usually has a cross-sectional of less than two times the plasma
sheath (not shown). As discussed herein, plasma sheath can exist on
each side of the slots. Hence if the total sheath thickness greater
than the slot width, there won't be any bulk plasma in between the
sheath hence plasma successfully pinch of by slots. However if the
slot width greater than the tow times the sheath thickness then the
plasma can exist inside the slots.
[0028] Regardless of the size of the slots, each slot tends to have
a straight opening, thereby providing a direct line-of-sight
between confined chamber volume 210 and external region 232
(outside chamber volume) of processing chamber 200. As a result,
the electrons of the RF field are able to traverse through the
openings provided by the slots and leak into external region 232 of
processing chamber 200. Given certain conditions (such as a
high-pressurized environment), the presence of an RF field in the
outside chamber volume may cause the processed byproduct gas (such
as neutral gas species) to ignite and form plasma in external
region 232. Thus, plasma unconfinement may result.
[0029] In an embodiment, a multi-peripheral ring arrangement is
provided to prevent plasma unconfinement. The multi-peripheral ring
arrangement may include a secondary peripheral ring 270 surrounding
primary peripheral ring 212. A manifold 284 may exist between
primary peripheral ring 212 and secondary peripheral ring 270 to
create a route for the processed byproduct gas (such as neutral gas
species) to be exhausted.
[0030] Secondary peripheral ring 270 may be made from a dielectric
material, in an embodiment. In another embodiment, secondary
peripheral ring 270 may be made from a conductive material such as
steel, for example.
[0031] The dimension of second peripheral ring 270 may vary, in an
embodiment. In an example, both peripheral rings may have the same
dimension. In another example, secondary peripheral ring 270 may
have a larger dimension than primary peripheral ring 212. Although
in one embodiment, secondary peripheral ring 270 may have a smaller
dimension than primary peripheral ring 212; however, the dimension
of secondary peripheral ring 270 is preferably configured to be
sufficiently large to prevent the RF current from escaping into the
outside chamber volume.
[0032] Secondary peripheral ring 270 may include a plurality of
slots (such as slots 276a, 276b, 276c, 276d, and 276e). The shape
of the slots on secondary peripheral ring 270 may vary, including
but are not limited to a radial geometry and a peripheral shape. In
an embodiment, the slots of secondary peripheral ring 270 and
primary peripheral ring 212 may have the same geometry. However,
the multi-peripheral ring arrangement may also provide for
peripheral rings with different slot shapes. Regardless of the
geometric design of the slots on both peripheral rings, the slots
are configured to be large enough to enable the processed byproduct
gas (e.g., neutral gas species) to be exhausted from confined
chamber volume 210 while preventing the formation of plasma in the
outside chamber volume. In an example, each slot may be smaller
than twice the size of a plasma sheath.
[0033] Although FIGS. 2A and 2B show secondary peripheral ring 270
as having more slots than primary peripheral ring 270, other
configurations may exist. In one embodiment, primary peripheral
ring 212 may have the same number of slots as secondary peripheral
ring 270. In another embodiment, primary peripheral ring 212 may
have fewer slots than secondary peripheral ring 270. The number of
slots on secondary peripheral ring 270 in comparison to primary
peripheral ring 212 may depend upon a manufacturer's
preference.
[0034] In an embodiment, secondary peripheral ring 270 is
positioned at a fixed location relative to primary peripheral ring
212, and the wall of secondary peripheral ring 270 is configured to
block the flow of RF current. Accordingly, the slots (such as slots
276a, 276b, 276c, 276d, and 276e) of secondary peripheral ring 270
are offset relative to the slots (226a, 226b, 226c, and 226d) of
primary peripheral ring 212 (such as shown in FIG. 2B).
[0035] In other words, if the electrons from the RF field traverse
through slot 226a of primary peripheral ring 212 in a direction 280
(of FIG. 2C), the electrons may travel through manifold 284 to
encounter a section of wall 282 instead of one of the slots (such
as slots 276a, 276b, 276c, 276d, and 276e) on secondary peripheral
ring 270. Thus, a direct line-of-sight from confined chamber volume
210 to external region 232 of processing chamber is substantially
eliminated with the multi-peripheral ring arrangement. Instead, the
electrons of the RF field may be deflected back into confined
chamber volume 210.
[0036] In an embodiment, a small level of DC bias (from negative 10
to positive 100, for example) or a low frequency RF current may be
applied to secondary peripheral ring 270 to create a charge on wall
282. The built-up charge on wall 282 may help deflect the electrons
back into confined chamber volume 210. Thus, even if the pressure
environment in external region 232 is conducive for igniting plasma
(such as a high-pressurized environment), the absence of an RF
field substantially eliminates the possibility of plasma ignition
outside of confined chamber volume 210.
[0037] Although the slots are shown as being located only at the
bottom of each of the peripheral rings (212 and 270), other
configurations may exist. Each section (250, 252, and 254) may be
employed to exhaust the processed byproduct gas, such as processed
byproduct gas, such as neutral gas species (as shown in FIG. 2D).
The number of sections that may be employed may depend upon the
rate of conductance required. For example, in a chamber that has a
normal rate of conductance, slots may be positioned in only one
section. However, for a processing chamber that requires a higher
rate of exhaust, two or more sections may be employed. Accordingly,
the multi-peripheral ring arrangement may be extended into the
sections that are employed for exhausting the processed byproduct
gas (such as neutral gas species).
[0038] FIG. 3 shows, in an embodiment of the invention, a simple
diagram of a partial view of a processing chamber environment with
a multi-peripheral ring arrangement with a conductive control ring.
The discussion about the conductive control ring as a pressure
control and plasma confinement arrangement is discussed in
Application Docket Number P1990P/LMRX-P185P1 entitled "A Local
Plasma Confinement and Pressure Control Arrangement and Methods
Thereof", which is incorporated herein by reference.
[0039] Consider the situation wherein, for example, the pressure
volume/level within a confined chamber volume 310 is below an
acceptable threshold value. In the prior art, to perform pressure
control, a vacuum valve may be employed. However, pressure control
using a vacuum valve does not provide for localized control.
Instead, not only does the pressure volume/level change within
confined chamber volume 310, but the pressure environment in
external region 332 (outside chamber volume) of a processing
chamber 300 is also affected. Thus, if the RF current is able to
leak out from confined chamber volume 310, the RF current may
interact with the processed byproduct gas (such as neutral gas
species) to ignite an unconfined plasma.
[0040] In an embodiment of the invention, a conductive control ring
320 is employed to provide local pressure control. Conductive
control ring 320 may be made from a dielectric material and may be
positioned next to the multi-peripheral ring arrangement, which
includes a primary peripheral ring 312 and a secondary peripheral
ring 314, in this example. In a preferred embodiment, the
conductive control ring surrounds at least one of the peripheral
rings. In other words, the conductive control ring is positioned
closer to the outside chamber volume, thereby providing a barrier
against the possibility of plasma unconfinement.
[0041] In an embodiment, the number of slots and the positioning of
the slots on conductive control ring 320 may vary. For example, the
number of slots and the positioning of the slots on conductive
control ring 320 may match the number of slots and the positioning
of the slots on secondary peripheral ring 314. In another example,
the number of slots and/or positioning of the slots on conductive
control ring 320 may differ from that of secondary peripheral ring
314. By actuating/rotating conductive control ring 320, the degrees
of offsets between the slots of conductive control ring 320 and the
slots of secondary peripheral ring 314 may be manipulated to
provide localized pressure control.
[0042] In an embodiment, the degrees of offsets may range from a
zero offset to a full offset. As discussed herein, zero offset
refers to a situation in which at least a first slot on the
secondary peripheral ring matches with a first slot on the
conductive control ring to provide an unblock passage for the
exhausting gas. As discussed herein, a full offset may refers to a
situation in which at least one slot on the secondary peripheral
ring is covered by a slot on the conductive control ring such that
the passage for exhausting gas is blocked. As can be appreciated
from the foregoing, the offset relationship between the secondary
peripheral ring and the conductive control ring may also include a
partial offset such that at least a portion of the passage for
exhausting gas is available.
[0043] In the prior art, the high-pressurized environment within a
confined chamber volume may also cause the size of the plasma
sheath to shrink and enable the plasma to escape the confined
chamber volume. Since the change in the pressure volume/level is
not localized within the confined chamber volume, the outside
chamber volume may now have an environment that is conducive for
sustaining the unconfined plasma.
[0044] In an embodiment, conductive control ring 320 may surround
the multi-peripheral ring arrangement to substantially prevent the
plasma from flowing into external region 332 (outside chamber
volume) of processing chamber 300. By manipulating conductive
control ring 320, the opening of each slot on secondary peripheral
ring 314 may be altered. In an example, to increase the pressure
level/volume within confined chamber volume 310, conductive control
ring 320 may be actuate/rotated to cause the slots on conductive
control ring 314 to overlap a portion of the slots on secondary
peripheral ring 314. Accordingly, instead of a plurality of
fixed-sized slots available for exhausting the processed byproduct
gas (such as neutral gas species), the actuation/rotation of
conductive control ring 320 has transformed the fixed-sized slots
into a plurality of variable-sized slots.
[0045] In an embodiment, conductive control ring 320 is moved by a
motor (not shown). The motor may be part of an automatic feedback
arrangement. The automatic feedback arrangement also include a
control module (not shown) configured for providing instructions to
the motor when conductive control ring 320 is to be adjusted, in an
embodiment. In an example, the pressure volume/level within
confined chamber volume 310 has fallen outside an acceptable
threshold value. Based on data from a sensor (not shown), the
control module may calculate a new position for conductive control
ring 320. Thus, conductive control ring 320 may be adjusted
automatically without human intervention.
[0046] In an embodiment, the shape of the conductive control ring
may vary. In an example, if the processing chamber has a normal
rate of conductance, then the multi-peripheral ring arrangement may
have a configuration in which only one section (350, 352, and 354)
have slots for exhausting the processed byproduct gas (such as
neutral gas species). Accordingly, conductive control ring 320 may
be configured to have corresponding slots in the same section.
However, if a higher rate of conductance is required, then two or
more sections of the multi-peripheral ring arrangement may have
slots to exhaust the processed byproduct gas (such as neutral gas
species). Similarly, conductive control ring 320 may be configured
accordingly to support multi-peripheral ring arrangement.
[0047] As can be appreciated from the forgoing, one or more
embodiments of the present invention provide for a multi-peripheral
ring arrangement. By providing a secondary peripheral ring, the
direct line-of-sight provided by the slots of the primary
peripheral ring is substantially eliminated. Without a direct
line-of-sight, the RF field is substantially prevented from leaking
into the outside chamber volume. Thus, plasma unconfinement is
substantially eliminated and a wider processing window may be
available for substrate processing.
[0048] While this invention has been described in terms of several
preferred embodiments, there are alterations, permutations, and
equivalents, which fall within the scope of this invention.
Although various examples are provided herein, it is intended that
these examples be illustrative and not limiting with respect to the
invention. In addition, even though the invention is described in
relation to a capacitively-coupled plasma (CCP) processing system,
the invention may also be applied in relation to an
inductively-coupled plasma processing system or a hybrid plasma
processing system.
[0049] Also, the title and summary are provided herein for
convenience and should not be used to construe the scope of the
claims herein. Further, the abstract is written in a highly
abbreviated form and is provided herein for convenience and thus
should not be employed to construe or limit the overall invention,
which is expressed in the claims. If the term "set" is employed
herein, such term is intended to have its commonly understood
mathematical meaning to cover zero, one, or more than one member.
It should also be noted that there are many alternative ways of
implementing the methods and apparatuses of the present invention.
It is therefore intended that the following appended claims be
interpreted as including all such alterations, permutations, and
equivalents as fall within the true spirit and scope of the present
invention.
* * * * *