Plasma source for patterned deposition

Abstract

A plasma source (100) includes a plasma deposition head (110) having an aperture (111) for delivering an atmospheric pressure plasma to a substrate (50). An electrode plate (120) is mounted in a slot cavity (112) of the deposition head. A gas supply system (130) is arranged for supplying a gas mass flow toward the substrate through a gap (G) between the electrode plate and the deposition head. A removable insert (140) is removably mounted in the gap, the removable insert being arranged for patterning an atmospheric pressure plasma flow towards the substrate by locally blocking a section of the slot cavity thereby forming a patterning channel between the gas supply system and the aperture.

Description

Technical Field

[0001] This invention relates to a plasma source, such as a plasma source for space ALD. Background Technology

[0002] In atomic layer deposition (ALD), the substrate is sequentially exposed to half-reactions, such as in plasma-enhanced ALD, one of which is formed by plasma material. The ALD plasma deposition head typically contains high-voltage electrodes to generate plasma, which is supplied toward the substrate as it moves or reverses relative to the deposition head. In this way, the substrate can be additively fabricated by depositing various layers. Patterns or traces can be created on the substrate by partially interrupting the half-reactions (e.g., by controlling the plasma supply toward the substrate). Typically, in such patterned deposition, it is important that the size of the pattern be controlled within small tolerances. This allows for improved resolution of the patterned substrate. Alternatively, in other words, the spacing between pattern edges can be reduced. In this regard, the edges of the pattern need to be as sharp or well-defined as possible. For example, the edge width, defined as the transition width between deposited and undeposited areas on the substrate, is preferably as small as possible, for example, less than 0.5 mm.

[0003] Patterning on a substrate is known to be achieved by patterning electrode plates themselves. For example, a metal electrode within a dielectric can be interrupted across the width of the electrode plate, for instance, by being composed of separate sections. However, such patterned electrodes can produce relatively wide (non-sharp) edges in the pattern on the substrate, for example, due to the diffusion of free radicals as they flow towards the substrate. Furthermore, since each patterned electrode is specifically designed to produce a particular pattern on the substrate, electrode replacement is required to produce different patterns from the plasma source. Typically, electrode plates are expensive and fragile, so the use of patterned electrodes may not be preferred in practice.

[0004] The purpose of this invention is to provide a simple and flexible solution for reducing the edge width of ALD patterns. Summary of the Invention

[0005] In summary, the present invention provides a plasma source comprising a plasma deposition head, an electrode plate, and a gas supply system. The plasma deposition head includes an orifice for delivering atmospheric pressure plasma from the deposition head to a substrate, and includes a slotted cavity extending from the orifice. The electrode plate is mounted in the slotted cavity and extends from the interior of the deposition head toward the orifice. The gas supply system is arranged to supply a gas mass flow to the substrate through a gap between the electrode plate and the deposition head, and the electrode plate is arranged to generate atmospheric pressure plasma in the gas mass flow.

[0006] A removable insert is removably mounted in the gap. The removable insert is arranged to form a patterned channel between the gas supply system and the orifice by partially blocking a section of the slot cavity, thereby patterning the atmospheric pressure plasma flow toward the substrate.

[0007] Therefore, the removable insert creates a patterned atomic layer deposition on the substrate by locally allowing and blocking plasma formation along the electrode plate. By locally interrupting (e.g., blocking) the gas mass flow, free radicals formed in the plasma are guided toward the substrate via different channels near the interruption, thereby minimizing free radical diffusion and reducing the pattern edge width.

[0008] Because the inserts are removable and therefore interchangeable, the airflow pattern toward the substrate can be altered by replacing them with inserts of different types or shapes. In other words, the pattern of layer deposition can be selectively changed by installing different types of inserts in the gaps without modifying the electrode plates or deposition head.

[0009] The removable insert can be made of readily available and high-precision machinable materials, such as sheet material, to provide patterned channels in the gap. For example, the removable insert can be provided with grooves, cutouts, holes, or ribs. The patterned channel is at least partially formed by the removable insert. For example, some walls of the patterned channel can be formed by the walls of a slotted cavity and / or the sides of an electrode plate, while other patterned channel walls are formed by the removable insert. Alternatively, the patterned channel can be fully integrated into the removable insert, for example, through holes or slots within the removable insert.

[0010] Preferably, the removable insert includes one or more slits extending between the gas supply system and the orifice to guide the mass flow of air.

[0011] In some embodiments, the removable insert includes a plurality of shims arranged in a stacked manner. For example, each shim has a thickness, and multiple shims are stacked to obtain the total thickness of the removable insert to bridge the gap between the electrode plate and the deposition head. By adapting the total thickness of the removable insert in this way, for example to match the gap width, different types of plasma sources can provide replaceable and modifiable patterned channels between the electrode plate and the deposition head.

[0012] Preferably, at least one of the plurality of gaskets is provided with a cut extending between the gas supply system and the orifice.

[0013] In some embodiments, the gas supply system includes a plurality of gas supply channels and outlets that extend across the width of the electrode plate into a slotted cavity, and the removable insert substantially spans the width of the electrode plate. The removable insert can selectively close some of the gas supply channels and outlets, while other gas supply channels and outlets remain open via cutouts extending towards the orifice in the removable insert. Thus, the mass flow of gas supplied by the gas supply system is either partially interrupted or allowed to pass along one or more gaskets.

[0014] The plasma source may include more than one removable insert. For example, each removable insert may only span a portion of the electrode plate width to partially block a section of the slot cavity, leaving other sections of the slot cavity without removable inserts. For example, the removable insert may be installed only in the central portion of the gap between the electrode plate and the deposition head, thereby forming different channels on opposite lateral sides of the removable insert.

[0015] To further reduce the edge width of the pattern created on the substrate, the one or more removable shim plates can divide the gap into a first channel for guiding a gas mass flow adjacent to a first portion of the electrode plate, and a second channel isolated from the electrode plate for guiding a second portion of the gas mass flow. Thus, in use, atmospheric pressure plasma is generated in the first portion, while no plasma is generated in the second portion. In this way, the second portion of the gas mass flow can be used to purge the atmospheric pressure plasma flow. Preferably, the first and second channels are arranged in an alternating pattern along the width of the electrode plate. The (lateral) diffusion of the plasma gas can be further restricted by implementing a patterned supply of adjacent plasma gas, for example, by alternating a purge gas supply with a patterned supply of plasma gas.

[0016] Preferably, the gas supply system is arranged to supply a first portion of the gas mass flow through the first channel and a second portion of the gas mass flow through the second channel, wherein the first portion is equal to the second portion. When the gas supply through the first and second channels is substantially equal in mass flow rate, optimal counteracting of the purge gas flow of the atmospheric pressure plasma flow can be achieved, thereby reducing the pattern edge width.

[0017] The first channel may be defined, for example, by a first cut in one or more first gaskets, and the second channel may be defined, for example, by a second cut in one or more second gaskets.

[0018] Preferably, the removable insert is clamped between the electrode plate and the deposition head to facilitate the installation and replacement of the removable insert.

[0019] In some embodiments, the removable insert is made of a conductive material to provide a localized electrical connection between the electrode plate and the deposition head. This locally minimizes the potential difference between the electrode plate and the deposition head, for example, in regions between different channels of the patterned channel. Accordingly, in use, plasma is generated only in said channels.

[0020] Preferably, the electrode plate comprises a high-voltage electrode that spans substantially the width of the electrode plate in a continuous manner. Therefore, the electrode plate is capable of generating plasma across its entire width, rather than patterning the electrode itself, for example, through interrupted high-voltage electrodes. This provides optimal flexibility for substrate patterning, as the pattern depends only on removable and interchangeable shim plates (sets) mounted in the gap between the electrode plate and the deposition head.

[0021] In some embodiments, the electrode plate is suspended at a distance from each parallel wall of the slot cavity, wherein the gas supply system is arranged to supply a first gas mass flow and a second gas mass flow through corresponding first and second gaps on opposite sides of the electrode plate, wherein a removable insert is removably mounted in the first and second gaps.

[0022] This invention is not limited to removable inserts for patterning plasma gas flows; it can also be applied to patterning non-plasma gases, such as precursor gases. Patterning the precursor gas flow toward the substrate can also form corresponding patterns on the substrate. By simultaneously patterning the plasma gas flow and the precursor gas flow toward the substrate, better edge sharpness of the deposited pattern can be provided.

[0023] For example, the plasma deposition head may include an additional orifice for conveying a precursor gas flow from the deposition head to the substrate, and an additional slot cavity extending from the additional orifice, wherein the gas supply system is arranged to supply the precursor gas flow to the substrate through the additional slot cavity, wherein an additional removable insert is removably mounted in the additional slot cavity, the additional removable insert being arranged to pattern the precursor gas flow to the substrate by partially blocking sections of the additional slot cavity, thereby forming an additional patterned channel between the gas supply system and the additional orifice.

[0024] Preferably, the additional removable insert forms an additional patterned channel identical to the patterned channel formed by the removable insert, so as to maximize the edge sharpness of the pattern deposited on the substrate. Attached Figure Description

[0025] The present invention will be further illustrated in the accompanying drawings:

[0026] Figure 1An embodiment of a plasma source provided with a removable pad is shown;

[0027] Figure 2A and Figure 2B It shows the way Figure 1 The gas mass flow of the plasma source and the resulting pattern on the substrate;

[0028] Figure 3 Another embodiment of the plasma source is shown, comprising a stack of removable pads;

[0029] Figure 4 Another embodiment of a plasma source is provided, comprising a first removable pad and a second removable pad;

[0030] Figure 5A and Figure 5B It shows the way Figure 4 The gas mass flow of the plasma source and the resulting pattern on the substrate;

[0031] Figure 6 Another or further embodiment of the plasma source described herein is shown; and

[0032] Figure 7 An embodiment of the removable pad for the plasma source described herein is depicted. Detailed Implementation

[0033] The present invention will be described more fully below with reference to the accompanying drawings, which illustrate embodiments of the invention. In the drawings, the absolute and relative dimensions of systems, components, layers, and regions may be exaggerated for clarity. Embodiments may be described with reference to schematic illustrations and / or cross-sectional views of possible idealized embodiments and intermediate structures of the invention. Throughout the description and drawings, the same numbers refer to the same elements. Relative terms and their derivatives should be interpreted as referring to orientations as shown in the described or discussed drawings. Unless otherwise stated, these relative terms are for descriptive convenience and do not require the system to be constructed or operated in a particular orientation.

[0034] Figure 1A top view of an embodiment of a plasma source 100 is provided, which is arranged to generate a patterned atmospheric pressure plasma flow, particularly for plasma-enhanced (space) atomic layer deposition on a substrate 50. In use, the substrate 50 and the plasma source 100 move relative to each other, for example, along a direction of movement D, and the plasma source 100 delivers an atmospheric pressure plasma flow from a deposition head 110 to the substrate 50, the deposition head including an aperture facing the substrate 50. The aperture is formed by the edge of a rectangular slot cavity 112 in the deposition head 110. Preferably, the aperture is oriented perpendicular to the direction of movement D. For example, the length of the slot cavity 112 spans at least a portion of the width of the substrate 50.

[0035] Electrode plate 120 is mounted against a first parallel wall 114 of slot cavity 112, thereby forming a gap G between the electrode plate and the opposing second parallel wall 113 of slot cavity. Electrode plate 120 includes a high-voltage electrode that substantially spans the width of electrode plate 120 and is arranged to generate a potential difference between electrode plate and opposing second parallel wall 113 of slot cavity. Gas mass flow is supplied from a gas supply system to the orifice through gap G. As the gas mass flow in use passes along the electrode plate, the potential difference across gap G converts the gas into (atmospheric pressure) plasma.

[0036] The atmospheric pressure plasma flow is patterned, for example, interrupted in a direction perpendicular to the direction of movement D, to deposit parallel tracks on the substrate 50, such as... Figure 2A and Figure 2B As shown. To achieve this, a removable insert 140 is installed in the slot cavity 112, for example, across the gap G between the electrode plate 120 and the opposing parallel wall 113. The removable insert 140 blocks a section of the gap G while allowing gas to pass through other sections of the gap G, thereby effectively creating distinct, separate channels adjacent to the insert.

[0037] The insert 140 is removable because it can be installed within the gap G and removed therefrom without altering the design or construction of other parts of the plasma source 100, such as the electrode plate 120 or the deposition head 110. Therefore, the removable insert 140 is interchangeable, for example, with other types or shapes of removable inserts 140 arranged to provide other atmospheric pressure plasma flow patterns. The removable insert 140 can be secured to the deposition head 110 or the electrode plate 120, for example, by screws or pins, or it can be clamped between the deposition head 110 and the electrode plate 120 for easy installation and removal. Preferably, the removable insert 140 includes alignment features, such as holes, protrusions, or edges, arranged to align the shim plate 140 relative to the electrode plate 120 and / or the deposition head 110.

[0038] The removable insert 140 is arranged to partially interrupt the gas mass flow between the gas supply system and the orifice. In other words, the removable insert 140 locally blocks gas from passing through certain sections of the gap G, while allowing gas to flow along the electrode plate 120 through other sections of the gap G and toward the orifice 111. In this way, atmospheric pressure plasma is generated only along the unblocked sections of the gap G, thereby providing a patterned atmospheric pressure plasma flow to the substrate 50.

[0039] The removable insert 140 preferably extends continuously between the gas supply system and the orifice, i.e., along the gas flow direction therebetween, preferably extending all the way to the orifice or slightly offset from it. This creates distinct channels for separately guiding portions of the gas mass flow through the gap G until they reach the orifice. This prevents the separated gas flows from merging or laterally diffusing before reaching the substrate 50.

[0040] Preferably, the removable plug 140 is made of a conductive material, particularly a material with a conductivity greater than 1 x 10⁻⁶. 0 The material used by Siemens / M is, for example, a metal or metal alloy, such as steel or aluminum. Thus, in the blocking sections where the pads form a bridging link between the electrode plate 120 and the deposition head 110, the potential difference across the gap G is locally reduced to prevent plasma formation in these sections.

[0041] Figure 3 A side view of an embodiment of the plasma source 100 is shown. A plasma deposition head 110 is suspended above a substrate 50 and includes a slotted cavity 112 in which an electrode plate 120 is mounted. The electrode plate 120 includes a high-voltage electrode plate 121 encapsulated in a dielectric material, such as alumina. A gas supply system 130 is arranged to supply a mass flow of gas through a gap G between the electrode plate 120 and the deposition head 110. In use, the substrate 50 and the plasma deposition head 110 move relative to each other, for example, along a direction of movement D, while the gas supply system 130 supplies a mass flow of gas through the gap G to an aperture 111 facing the substrate 50.

[0042] A potential difference is generated across the gap G between the electrode plate 120 and the deposition head 110 to convert the gas mass flow into atmospheric pressure plasma, thereby exposing the substrate 50 to a half-reaction. A material layer is then deposited on the substrate 50.

[0043] like Figure 3As shown, a gasket stack 140 is mounted in the gap G between the electrode plate 120 and the deposition head 110. For example, the gasket stack 140 comprises several stacked plates. Each plate has a thickness spanning a portion of the gap G. When stacked together, the thickness of the gaskets 140 matches the width of the gap G. Each gasket plate 140 may be provided with a cut, hole, or groove extending between the gas supply system 130 and the orifice. Thus, when stacked together, the gasket plates 140 form a channel structure for locally blocking and allowing gas mass flow to the substrate 50.

[0044] Therefore, the gasket stack 140 is arranged to locally interrupt (e.g., block) the gas mass flow toward the orifice in some sections of the gap G (particularly along the width of the electrode plate 120), while allowing the gas mass flow to pass through in other sections of the gap G. Accordingly, as the deposition head 110 and the substrate 50 move relative to each other along the direction of movement D, some portions of the substrate 50 are not exposed to the atmospheric pressure plasma flow. Thus, material is deposited on the substrate in a pattern. Such a pattern includes, for example, parallel tracks along the direction of movement D.

[0045] Figure 4 A top view of another embodiment of the plasma source 100 is provided. Here, the removable insert 140 includes a first shim 140-1 and a second shim 140-2 to divide the gap G into a first channel 142 adjacent to the electrode plate 120 and a second channel 143 isolated from the electrode plate 120, for example, by a portion still covering the electrode plate via the removable insert 140. The first channel 142 is arranged to allow the generation of atmospheric pressure plasma in a first portion of the gas mass flow directed through the first channel 142 to the substrate 50. The second channel 143 prevents the generation of atmospheric pressure plasma in a second portion of the gas mass flow directed through the second channel 143 by isolating it from the electrode plate 120, for example, by offsetting the electrode plate 120. Thus, the second portion can be used to purge the atmospheric pressure plasma flow delivered through the first channel 142. The first channel 142 and the second channel 143 are arranged in an alternating pattern along the width of the electrode plate 120, for example, forming a checkerboard pattern. For example, the first channel 142 is defined by a first cut 141-1 in the first pad 140-1, while the second channel 143 is defined by a second cut 141-2 in the second pad 140-2. Preferably, the first and second cuts 141-1 and 141-2 do not overlap to prevent the first and second portions from mixing while still traveling through the gap G (i.e., before being conveyed to the substrate 50).

[0046] Instead of the gasket stacks 140-1 and 140-2, a single removable insert 140 can be installed between the electrode plate 120 and the deposition head 110. This single removable insert is provided with a plurality of first cuts or grooves arranged to allow a first portion of the gas mass flow to be delivered to the substrate 50, and a plurality of second cuts or grooves arranged to allow a second portion to be delivered to the substrate 50.

[0047] By providing a first channel 142 and a second channel 143 alternating along the width of the electrode plate, the edge width of the pattern deposited on the substrate can be further reduced, such as Figure 5A and 5B As shown. The "purge gas" flow provided through the second channel reduces the lateral diffusion of the atmospheric pressure plasma flow delivered to the substrate 50. This can be optimized by matching the mass flows of the first and second portions. For example, the gas supply system can be arranged to supply substantially equal gas mass flows through the first and second channels 142, 143.

[0048] Figure 6 Another exemplary embodiment of the plasma source 100 is provided. Here, in addition to the slotted cavity 112 for guiding the plasma gas flow along the electrode plate 120, the plasma deposition head 110 also includes an additional slotted cavity 112' extending from an additional orifice for conveying a non-plasma gas (e.g., precursor gas) flow from the deposition head to the substrate 50. The slotted cavity 112 and the additional slotted cavity 112' may be disposed in a single body of the plasma deposition head 110, such as Figure 6 As shown, but it can also be set in separate bodies that are mounted to each other, for example to accommodate other parts of the deposition head in between.

[0049] An additional removable insert 140' is removably mounted in an additional slot cavity 112' for patterning the non-plasma gas flow to the substrate 50 by partially blocking a section of the additional slot cavity 112', thereby forming an additional patterned channel between the gas supply system and the additional orifice.

[0050] Figure 7 An exemplary embodiment of the removable insert 140 is shown, with a high-voltage electrode 121 shown relative to the electrode plate of the plasma source 100 described herein. Preferably, the removable insert 140 is provided with an alignment arrangement 145, such as including holes, edges, or protrusions, which is arranged to align the removable insert 140 relative to the electrode plate and / or deposition head.

[0051] The removable plug 140 is arranged to partially interrupt the gas mass flow M through the high-voltage electrode 121 in use, for example, through a plurality of cuts 141 that expose the high-voltage electrode 121 and a plurality of obstacles 144 that cover the high-voltage electrode 121.

[0052] This invention is applicable not only to ALD applications where plasma sources provide improved patterned atomic layer deposition on a substrate, but also to other technologies, agricultural or industrial applications employing patterned layer deposition, such as chemical vapor deposition (CVD). The removable pad can be mounted not only in plasma gas channels but also in non-plasma gas slots to pattern the non-plasma gas flow. For example, alternatively or additionally, the removable pad can be mounted in a precursor gas slot to guide the precursor gas flow toward the substrate, wherein the removable pad is arranged to pattern the precursor gas flow to provide an alternative or additional method of patterning the substrate.

[0053] It will be apparent to those skilled in the art that the invention is not limited to any of the embodiments described herein, and that modifications can be made that are considered to be within the scope of the appended claims. Similarly, motion reversal is considered inherently disclosed and within the scope of the invention. In the claims, any reference numerals should not be construed as limiting the claims.

[0054] The terms "comprising" and "including" as used herein should not be interpreted in an exclusive or exhaustive sense, but rather in an inclusive sense. Therefore, expressions such as "comprising" or "including" as used herein do not exclude the presence of other elements, additional structures, additional actions, or steps besides those listed. Furthermore, the word "a" should not be interpreted as limited to "only one," but is used to mean "at least one," and does not exclude multiples. Features not specifically or explicitly described or claimed may be additionally included in the structure of the invention without departing from its scope.

[0055] Expressions such as "components for..." should be understood as "components configured for..." or "constructed as..." and should be interpreted to include equivalents of the disclosed structures. The use of expressions such as "critical," "preferred," and "particularly preferred" is not intended to limit the invention. They are explicitly indicated as such where a structure, material, or behavior is considered necessary. Those skilled in the art can typically make additions, deletions, and modifications without departing from the scope of the invention (as defined by the claims).

Claims

1. A plasma source (100), comprising: - A plasma deposition head (110) comprising an aperture (111) arranged for delivering atmospheric pressure plasma from the deposition head to a substrate (50), and a slotted cavity (112) extending from the aperture (111); and - An electrode plate (120) is mounted in the slot cavity (112) and extends from the interior of the deposition head (110) toward the orifice (111); - A gas supply system (130) is arranged to supply a mass flow of gas toward the substrate (50) through a gap (G) between the electrode plate (120) and the deposition head (110), wherein the electrode plate (120) is arranged to generate atmospheric pressure plasma in the mass flow of gas; The removable insert (140) is removably mounted in the gap (G) and is arranged to pattern the atmospheric pressure plasma flow onto the substrate (50) by partially blocking a section of the slot cavity (112) to form a patterned channel between the gas supply system (130) and the orifice (111).

2. The plasma source of claim 1, wherein the removable insert (140) includes one or more cutouts (141) extending between the gas supply system (130) and the orifice (111).

3. The plasma source (100) according to any of the preceding claims, wherein the removable insert (140) comprises a plurality of pads arranged in a stacked manner.

4. The plasma source (100) according to claim 3, wherein at least one of the plurality of gaskets is provided with a cut (141) extending between the gas supply system (130) and the orifice (111).

5. The plasma source (100) according to any of the preceding claims, wherein the removable insert (140) forms one or more first channels (142) adjacent to the electrode plate (120) for guiding a first portion of the gas mass flow, and one or more second channels (143) isolated from the electrode plate (120) for guiding a second portion of the gas mass flow, wherein the one or more first channels (142) and the one or more second channels (143) are arranged in an alternating pattern across the width of the electrode plate (120).

6. The plasma source (100) according to claim 5, wherein the gas supply system (130) is arranged to supply a first portion of the gas mass flow through the one or more first channels (142) and a second portion of the gas mass flow through a second channel (143), wherein the first portion is equal to the second portion.

7. The plasma source (100) according to claim 5 or 6, wherein the first channel (142) is defined by a first cut (141-1) in one or more first pads (140-1), and wherein the second channel (143) is defined by a second cut (141-2) in one or more second pads (140-2).

8. The plasma source (100) according to any of the preceding claims, wherein the removable insert (140) is clamped between the electrode plate (120) and the deposition head (110).

9. The plasma source (100) according to any of the preceding claims, wherein the removable insert (140) includes an alignment arrangement (145) configured to align the removable insert (140) relative to the electrode plate (120) and / or the deposition head (110).

10. The plasma source (100) according to any of the preceding claims, wherein the removable insert (140) is made of a conductive material for providing a local electrical connection between the electrode plate (120) and the deposition head (110).

11. The plasma source (100) according to any of the preceding claims, wherein the electrode plate (120) includes a high-voltage electrode (121) that spans substantially the width of the electrode plate (120) in a continuous manner.

12. The plasma source (100) according to any of the preceding claims, wherein the electrode plate (120) is suspended at a distance from each parallel wall (113, 114) of the slot cavity (112), wherein the gas supply system (130) is arranged to supply the gas mass flow and a first portion and a second portion through corresponding first gaps and second gaps (G1, G2) on opposite sides of the electrode plate (120), wherein a removable insert (140) is removably mounted in the first gaps and second gaps (G1, G2).

13. The plasma source (100) according to any of the preceding claims, wherein the plasma deposition head (110) includes an additional orifice for conveying a precursor gas flow from the deposition head to the substrate (50), and an additional slot cavity (112') extending from the additional orifice, wherein a gas supply system (130) is arranged to supply the precursor gas flow toward the substrate (50) through the additional slot cavity (112'), wherein an additional removable insert (140') is removably mounted in the additional slot cavity (112'), the additional removable insert (140') being arranged to pattern the precursor gas flow toward the substrate (50) by partially blocking a section of the additional slot cavity (112') to form an additional patterned channel between the gas supply system and the additional orifice.

14. The plasma source of claim 13, wherein the additional removable insert (140') forms an additional patterned channel identical to the patterned channel formed by the removable insert (140).

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