Method and apparatus for generating plasma

Abstract

A plasma source is provided that includes a body defining an input port, an output port, and at least one discharge section extending along a central longitudinal axis between the input port and the output port. The at least one discharge section includes a return electrode defining a first generally cylindrical interior volume having a first inner diameter, a feed plate with a feed electrode, a feed plate defining a second generally cylindrical interior volume having a second inner diameter, and at least one spacer defining a third generally cylindrical interior volume having a third inner diameter. The third inner diameter is different from the first or second inner diameters. The at least one discharge section is formed from a spacer disposed between the return electrode and the feed plate along the central longitudinal axis to define a generally cylindrical discharge gap for generating a plasma therein.

Description

[Technical Field]

[0001] The present invention generally relates to a plasma source configured to generate one or more regions of localized plasma within the plasma source. [Background technology]

[0002] Deposition processes, including chemical vapor deposition (CVD) processes, are commonly used in the fabrication of semiconductor devices. For example, in a typical CVD process, reactant gases are introduced into a reaction chamber and directed toward a heated substrate to induce a controlled chemical reaction, resulting in the deposition of a thin film on the surface of the substrate. During the deposition process, chamber pressure is precisely controlled by one or more mechanical devices, such as a vacuum valve, connected downstream from the reaction chamber. For example, an isolation valve is typically connected directly to the exhaust gas port of the reaction chamber, a throttle valve is located downstream from the isolation valve, and a vacuum pump is located further downstream from both the isolation valve and the throttle valve. The piping (e.g., pipelines and valves) between the reaction chamber and the vacuum pump is commonly referred to as the foreline, roughing line, or vacuum pump line.

[0003] During the deposition process, the throttle valve can periodically switch between open and closed positions to regulate the gas pressure inside the reaction chamber. The majority of materials generated from the reactant gases are deposited on the substrate surface inside the reaction chamber. However, some material also deposits on surfaces outside the reaction chamber, such as on the throttle valve. When undesirable materials accumulate on the throttle valve, the throttle valve's useful life can be reduced by, for example, causing seal wear, additional load, requiring a high-torque drive system, and changing conductance characteristics. Ultimately, the deposition of undesirable materials on the throttle valve reduces the valve's accurate operation, thereby reducing its ability to control the gas pressure inside the reaction chamber. Other vacuum valves along the vacuum pump line can be similarly affected by the deposition of undesirable materials. Additionally, the position of the throttle valve during closed-loop pressure control can provide useful diagnostic information. However, because the valve position changes depending on the amount of deposits, undesirable deposits on the valve can limit the usefulness of the valve position as an indicator of other changes in the system.

[0004] Typically, operators must manually remove valves in the mechanical system for cleaning or replacement, which requires tool downtime and venting of the foreline piping. Alternatively, remote plasma sources have been used for pump and foreline cleaning, where the plasma power is directed into the foreline but not too close to the valve to provide optimized, targeted component cleaning.

[0005] Additionally, during wafer deposition processes, unwanted materials generated from the reactant gases can also deposit along the vacuum pump lines as the reactant gases are exhausted from the processing chamber through the pump lines. Similar to throttle valves, the buildup of unwanted materials in vacuum pump lines can cause many problems, including clogging the pump lines and other downstream equipment, interfering with the normal operation of the associated vacuum pump, shortening the useful life of the vacuum pump, and contaminating the processing steps in the processing chamber.

[0006] While cylindrical plasma generators are known to be useful for valve / pump line cleaning, the discharge gap of these devices is along the longitudinal axis of the cylindrical structure, and the resulting discharge current is parallel to both the supply (e.g., power) and return (e.g., ground) electrodes of the structure. More specifically, in these devices, the supply and return electrodes are typically parallel to the gas flow direction, and the discharge gap is not clearly defined. Therefore, most of the resulting discharge current is concentrated at the edge of the supply electrode, where the voltage tends to be lowest and the total energy is minimized. This results in concentrated erosion at the edge of the supply electrode. Other known plasma generators have limited conductance due to a lack of line of sight between the generator's input and output ports (e.g., labyrinth structures), complex manufacturing due to complex structures and / or material compositions, and the use of inductive coupling for plasma generation, which can be difficult to ignite. Summary of the Invention

[0007] Therefore, there is a need for a plasma generator capable of generating a plasma based on capacitive discharge, the plasma generator including one or more substantially uniform discharge gaps configured to generate a substantially uniform current density therein. In some embodiments, the plasma generators described herein are suitably configured to integrate with a pump line to generate localized plasma at one or more target locations where deposition is problematic for the pump line. For example, the plasma generator can be a pipe-like structure with maximized pumping conductance.

[0008] In one aspect, a plasma source is provided that includes a body defining an input port, an output port, and at least one discharge section extending along a central longitudinal axis between the input port and the output port. The at least one discharge section includes a return electrode defining a first generally cylindrical interior volume having a first inner diameter disposed perpendicular to the central longitudinal axis, and a feed plate including a feed electrode. The feed plate defines a second generally cylindrical interior volume having a second inner diameter disposed perpendicular to the central longitudinal axis. The at least one discharge section also includes at least one spacer defining a third generally cylindrical interior volume having a third inner diameter disposed perpendicular to the central longitudinal axis. The third inner diameter is different from the first or second inner diameter. The at least one discharge section is formed from the spacer disposed between the return electrode and the feed plate along the central longitudinal axis, defining a generally cylindrical discharge gap for generating plasma therein. The first, second and third interior volumes share the same central longitudinal axis in the discharge section.

[0009] In another aspect, a method for manufacturing a plasma source is provided. The method includes assembling at least one discharge section, the assembling including providing a return electrode defining a first generally cylindrical interior volume having a first inner diameter disposed perpendicular to a central longitudinal axis, and providing a feed plate with a feed electrode. The feed plate defines a second generally cylindrical interior volume having a second inner diameter disposed perpendicular to the central longitudinal axis. Assembling the at least one discharge section also includes providing at least one spacer defining a third generally cylindrical interior volume having a third inner diameter disposed perpendicular to the central longitudinal axis, the third inner diameter being different from the first or second inner diameters, and disposing the spacer between the return electrode and the feed plate along the central longitudinal axis to define a generally cylindrical discharge gap for generating plasma therein. The first, second, and third interior volumes share the same central longitudinal axis in the discharge section. The method further includes forming a body comprising an input port, an output port, and at least one discharge section extending along a central longitudinal axis between the input port and the output port.

[0010] Any of the above aspects may include one or more of the following features: In some embodiments, the feeder plate further comprises at least one dielectric member laterally surrounding the feed electrode; In some embodiments, the at least one dielectric member of the feeder plate is a ring-shaped barrier dielectric member configured to laterally surround the ring-shaped feed electrode; In some embodiments, the at least one discharge section further comprises a ring-shaped isolation dielectric member disposed adjacent to the feeder plate along the central longitudinal axis.

[0011] In some embodiments, the first inner diameter of the return electrode and the second inner diameter of the supply plate are substantially the same. In some embodiments, the third inner diameter of the spacer is larger than the first and second inner diameters, such that a portion of the spacer's internal volume is recessed laterally relative to the return electrode and the supply plate. In some embodiments, a discharge gap is disposed in the recess of the spacer's internal volume. In some embodiments, the discharge gap is bounded longitudinally between a side of the return electrode and a side of the supply plate and laterally by the spacer. In some embodiments, a discharge is formed in the discharge gap between the side of the return electrode and the side of the supply plate, and the discharge current is adapted to flow parallel to the central longitudinal axis and perpendicular to the side. In some embodiments, the current density of the discharge current is substantially uniform around the central longitudinal axis.

[0012] In some embodiments, the return electrode is electrically grounded. In some embodiments, the at least one spacer of the discharge section comprises a plurality of spacers joined along the central longitudinal axis. In some embodiments, the spacers are made of a non-conductive material.

[0013] In some embodiments, the plasma source body comprises a plurality of discharge sections arranged along a central longitudinal axis, hi some embodiments, the plurality of discharge sections form a plurality of discontinuous discharge gaps along the central longitudinal axis for generating respective plasmas, hi some embodiments, the plurality of discharge gaps are substantially uniform.

[0014] In some embodiments, the return electrode, the supply plate, and the at least one spacer are joined by one of co-firing or adhesive bonding. The above-mentioned advantages of the present invention, together with further advantages, may be better understood by reference to the following description taken in conjunction with the accompanying drawings, in which: The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the present technology. [Brief explanation of the drawings]

[0015] [Figures 1a-1c] 1A-1C show cross-sectional, external and exploded views, respectively, of an exemplary plasma source according to some embodiments of the present invention. [Figure 2] 1a-1c illustrate exemplary configurations of the feed plate of the plasma source of FIGS. 1a-1c, according to some embodiments of the present invention. [Figure 3] 1A-1C illustrate an exemplary process for assembling the plasma source of FIGS. 1A-1C, according to some embodiments of the present invention. [Figures 4a-4c] 1A-1C show cross-sectional, external, and exploded views, respectively, of another exemplary plasma source according to some embodiments of the present invention. [Figure 5] 4a-4c depict exemplary configurations of the body of the plasma source according to some embodiments of the present invention. [Figure 6] 1a-1c illustrate exemplary gas flow patterns maintained within the interior volume of the plasma source of FIGS. 1a-1c, according to some embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Generally, the plasma sources described herein can include a dielectric barrier discharge structure for generating a localized plasma discharge. The dielectric barrier discharge structure can be formed by (i) a source electrode, (ii) a return electrode disposed adjacent to the source electrode, and (iii) a barrier dielectric material proximate to the source electrode and the return electrode, such as between the source electrode and the return electrode. A high-voltage alternating current can be supplied between the source electrode and the return electrode to activate the dielectric barrier discharge structure, thereby generating a localized plasma within the dielectric barrier discharge structure. In some embodiments, the power of the resulting plasma is about 20 watts to about 1000 watts. Furthermore, a source electrode, as described herein, generally refers to an electrode that receives a positive voltage, e.g., about 300 to about 2000 V, from a connected power source. A return electrode generally refers to an electrode maintained at a lower voltage than the source electrode. For example, the return electrode can be electrically grounded, floating (i.e., not connected to a power source), or biased to a negative voltage relative to the source electrode. In some embodiments, both the supply electrode and the return electrode of the dielectric barrier discharge structure are embedded in the barrier dielectric material, and the return electrode is either electrically grounded or not grounded (e.g., floating). In some embodiments, the supply electrode is embedded in the barrier dielectric material, while the electrically grounded return electrode is external to the barrier dielectric material. An embedded electrode assembly generally refers to a structure that includes a barrier dielectric material and has at least one of the return electrode or the supply electrode embedded in the barrier dielectric material.

[0017] 1a, 1b, and 1c show cross-sectional, external, and exploded views, respectively, of an exemplary plasma source 100 according to some embodiments of the present invention. The plasma source 100 includes a body defining an input port 106, an output port 108, and at least one discharge section 104 extending along and disposed about a central longitudinal axis A between the input port 106 and the output port 108. Each discharge section 104 can include a return electrode 116, one or more spacers 114, a feed plate 102, and an optional isolation dielectric member 122 disposed generally in a stacked configuration along the longitudinal axis A.

[0018] In some embodiments, the feed plate 102 of each discharge section 104 has a generally cylindrical interior volume 140 defining an inner diameter 142 perpendicular to the central longitudinal axis A. FIG. 2 illustrates an exemplary configuration of the feed plate 102 of the plasma source 100 of FIGS. 1a-1c, according to some embodiments of the present invention. As shown, the feed plate 102 may be ring-shaped and may include a ring-shaped feed electrode 204 laterally / radially surrounded by at least one ring-shaped dielectric member 202. For example, the outer ring-shaped dielectric member 202a may substantially surround the outer periphery of the feed electrode 204, and / or the inner ring-shaped dielectric member 202b may substantially surround the inner periphery of the feed electrode 204. In some embodiments, the radial width of the inner ring-shaped dielectric member 202b is approximately 0.06 inches, such that the feed electrode 206 is set back from the inner periphery of the feed plate 102 by this width. Thus, the feed electrode 204 may be radially sandwiched / embedded between the two dielectric members 202. In some embodiments, one or both of the dielectric members 202a, 202b are present. In alternative embodiments, no dielectric member is present in the feed plate 102, in which case the feed plate 102 consists solely of the feed electrode 204. Additionally, the feed plate 102 may include an outwardly extending flange 206 incorporating an outwardly extending portion of the feed electrode 204 configured to establish electrical contact between the feed electrode 204 and a power source (not shown). For example, during operation, a positive voltage, e.g., about 300 to about 2000 V, may be applied to the feed electrode 204 via the flange 206. The feed electrode 204 may be made of a conductive material, e.g., copper. The dielectric member 202 may be a barrier dielectric member constructed of a non-conductive material, such as a ceramic material.

[0019] 1a-1c, each discharge section 104 also includes at least one spacer 114, which may be ring-shaped and has a generally cylindrical interior volume 144 defining an inner diameter 146 perpendicular to the central longitudinal axis A. In some embodiments, the inner diameter 146 of each spacer 114 is larger than the inner diameter 142 of the feed plate 102. In some embodiments, each spacer 114 is made from a non-conductive material, such as a ceramic material.

[0020] Each discharge section 104 may further include a return electrode 116, which may be ring-shaped and have a generally cylindrical interior volume 148 defining an inner diameter 150 perpendicular to the central longitudinal axis A. In some embodiments, the inner diameter 150 of each return electrode 116 is smaller than the inner diameter 146 of each spacer 114. In some embodiments, the inner diameter 150 of each return electrode 116 is approximately the same as the inner diameter 142 of each feed plate 102. The return electrode 116 may be made of a conductive material, for example, copper. In some embodiments, the return electrode 116 is electrically grounded.

[0021] In some embodiments, each discharge section 104 further includes an isolation dielectric member 122 positioned adjacent to the feed plate 102 of each discharge section 104, e.g., next to and in physical contact with the feed plate 102 along the longitudinal axis A. In some embodiments, the isolation dielectric member 122 is made of a non-conductive material, e.g., a ceramic material. In some embodiments, as shown in FIGS. 1a-1c, each isolation dielectric member 122 is ring-shaped and has a generally cylindrical interior volume 152 defining an inner diameter 154 perpendicular to the central longitudinal axis A. The inner diameter 154 of each isolation dielectric member 122 can be approximately the same as the inner diameter 142 of the feed plate 102.

[0022] 1a-1c, at least one spacer 114 is stacked and positioned along the longitudinal axis A between the return electrode 116 and the feed plate 102 such that the respective interior volumes 140, 144, 148 of the feed plate 102, the spacer 114, and the return electrode 116 are concentric and share the same central longitudinal axis A. Thus, the at least one spacer 114 is longitudinally sandwiched between the return electrode 116 and the feed plate 102. In this configuration, the inner diameter 146 of the spacer 114 is larger than the inner diameter 142 of the feed plate 102 and the inner diameter 150 of the return electrode 116 (the diameters 142 and 150 can be substantially the same), such that a portion of the interior volume 144 of the spacer 114 is radially recessed relative to the interior volumes 140, 148 of the feed plate 102 and the return electrode 116. This forms a ring-shaped recessed region 120 within the interior volume 144 of the spacer 114 that can function as a discharge gap for generating plasma. The discharge gap 120 is thus bounded longitudinally between the side of the return electrode 116 and the side of the feed plate 102, and laterally by the inner vertical surface of the spacer 114. In some embodiments, two or more spacers 114 (e.g., two spacers 114 as shown in FIGS. 1a-1c) are stacked together along the central longitudinal axis A and sandwiched between the return electrode 116 and the feed plate 102 to enlarge the discharge gap 120 within each discharge section 104. Generally, the size of the discharge gap 120 can be adjusted by increasing or decreasing the number of spacers 114 present within the discharge section 104 and / or by changing the length of the inner diameter 146 of each spacer 114.

[0023] Furthermore, in the stacked arrangement of the discharge section 104, the separating dielectric member 122 can optionally be positioned next to the feed plate 102 along the longitudinal axis A such that the interior volumes 152, 140 of the dielectric member 122 and the feed plate 102 are substantially aligned and concentric. In this configuration, one side of the feed plate 102 faces the discharge gap 120, and the opposite side of the feed plate 102 is in physical contact with the separating dielectric member 122. Thus, the separating dielectric member 122 and the feed plate 102 can form an embedded electrode assembly, with the feed electrode 204 embedded between the barrier dielectric member 202 of the feed plate 102 and the separating dielectric member 122 adjacent to the feed plate 102. Additionally, each discharge section 104 may form a dielectric barrier discharge structure including (i) an embedded electrode assembly having a supply electrode 204 embedded in a barrier dielectric member 202 and an isolation dielectric member 122, and (ii) a return electrode 116 disposed outside the embedded electrode assembly (e.g., separated from the embedded electrode assembly by a discharge gap 120).

[0024] When the discharge section 104 is activated, a discharge current can be formed in each discharge gap 120 between the side of the return electrode 116 and the side of the feed plate 102. More specifically, the discharge current can flow parallel to the central longitudinal axis A between the side surfaces and, therefore, in a direction substantially perpendicular to both of the side surfaces. In some embodiments, the current density of the discharge current in the discharge gap 120 is substantially uniform around the central longitudinal axis A, such that each discharge gap 120 can optimally utilize its entire discharge area to generate a substantially uniform current density. Because each discharge gap 120 is configured to uniformly distribute the discharge current, structural erosion is more uniformly distributed, resulting in a longer life for the plasma source 100. Furthermore, even if the barrier discharge erodes through the feed plate 102, the return electrode 116, and / or the separating dielectric member 122 of the embedded electrode assembly in the discharge section 104, the integrity of the vacuum vessel is still maintained. In some embodiments, each discharge gap 120 is operated at a pressure between 67 Pa and about 670 Pa (0.5 Torr and about 5 Torr).

[0025] In some embodiments, the plasma source 100 includes multiple discharge sections 104 arranged in a stacked manner (e.g., to form a series of stacked rings) along a central longitudinal axis A, where the discharge sections 104 are concentric and share the same central longitudinal axis A. The multiple discharge sections 104 are configured to form discrete, discontinuous local plasmas within their respective discharge gaps 120. In some embodiments, the discharge gaps 120 of the multiple discharge sections 104 are substantially uniform in dimension (e.g., the same number / type of spacers 114 are used) to generate a substantially uniform region of plasma along the longitudinal axis A. Generally, the more discharge sections present in the plasma source 100, the higher the power generated by the plasma source 100. In some embodiments, as shown in FIGS. 1a-1c, the return electrodes 116 of the multiple discharge sections 104 are electrically connected via their respective electrical contacts 134 to a conductive bus bar 130 positioned proximate to the stacked discharge sections 104 and oriented substantially parallel to the longitudinal axis A. The bus bar 130 is configured to be in electrical communication with a power source at one end such that the bus bar 130 supplies substantially the same power to the multiple return electrodes 116, electrically grounding these electrodes 116 or setting them to a lower voltage relative to the supply electrode 204.

[0026] In some embodiments, each of the input port 106 and the output port 108 of the plasma source 100 is part of the discharge section 104 of the plasma source 100. For example, the input port 106 can be part of the return electrode 116 of one discharge section 104 in an input region of the plasma source 100, and the output port 108 can be part of the return electrode 116 of another discharge section 104 in an output region of the plasma source 100. The inner diameter of each of the input port 106 and the output port 108 can be approximately the same as the inner diameter 142 of the feed plate 102, the inner diameter 154 of the separating dielectric member 122, and / or the inner diameter 150 of the return electrode 116. In some embodiments, the input port 106, located at one end of the plasma source body along the longitudinal axis A, is configured to couple to an input pump line segment (not shown). The output port 108 can be located at an opposite end along the longitudinal axis A from the input port 106 for coupling to an output pump line segment (not shown). Thus, when the plasma source 100 is connected to an input pump line segment at the input port 106 and to an output pump line segment at the output port 108, the plasma source 100 becomes a segment of the entire pump line. Additionally, a substantially constant pumping speed and / or conductance can be maintained throughout the resulting connected pump line structure, regardless of whether fluid is moving through the pump line segment or the plasma source 100. In some embodiments, the inner diameter 154 of the separating dielectric member 122, the inner diameter 142 of the feed plate 102, the inner diameter 150 of the return electrode 116, and the inner diameters of the input port 106 and output port 108 are substantially the same as the inner diameters of the input and output pump line segments to which the plasma source 100 is connected. Furthermore, each discharge gap 120 extends radially outward, i.e., has a larger inner diameter relative to the inner diameter of the pump line segment.

[0027] During operation, as cleaning gas flows from the pump line into the plasma source 100 in a flow path parallel to the longitudinal axis A, the discharge sections 104 in the plasma source 100 can be activated to generate a discharge current in the discharge gap 120 of each discharge section 104, the discharge current adapted to dissociate gas in the flow path and generate a local plasma discharge in each discharge gap 120. To activate one or more discharge sections 104, the supply plates 104 can be supplied with a voltage via their respective flanges 206, and the return electrodes 116 can be floating or electrically grounded / set to a lower voltage via their connections 134 to the bus bar 130. As described above, the resulting discharge current in each discharge section 104 can be substantially parallel to the longitudinal axis A and uniformly distributed about the longitudinal axis A. In some embodiments, the plasma discharge can have a power of about 20 watts to about 1000 watts. Each localized plasma discharge is adapted to fill a majority of the volume of the corresponding discharge gap 120, thereby maintaining a generally toroidal shape about the longitudinal axis A. Radicals generated within the discharge gap 120 of the plasma source 100 may be brought into the flow path by diffusion or turbulence. In some embodiments, the discharge current partially dissociates the gas within the flow path, and the power level used to operate the discharge section 104 is selected to be reduced to reduce heating and extend the life of the plasma source 100. Partial dissociation of the input gas can generate a sufficient amount of gaseous radical species to produce acceptable cleaning results of the pump line segments.

[0028] 3 shows an exemplary process 300 for assembling the plasma source 100 of FIGS. 1a-1c, according to some embodiments of the present invention. The discharge section 104 of the plasma source 100 is assembled by first providing (i) the feed plate 102 in step 302, (ii) one or more spacers 114 in step 304, and (iii) the return electrode 116 in step 306. In some embodiments, the inner diameter 146 of each spacer 114 is larger than the inner diameters 142, 150 of the feed plate 102 and the return electrode 116. In some embodiments, the inner diameters 142, 150 of the feed plate 102 and the return electrode 116 are substantially the same. In some embodiments, a separating dielectric member 122 is further provided having an inner diameter 154 approximately the same as the inner diameter of the feed plate 102.

[0029] In step 308, the discharge section 104 is formed by stacking the return electrode 116, the spacer 114, the feed plate 102, and optionally the separating dielectric member 122 together along the longitudinal axis A. For example, the spacer 114 can be sandwiched between the return electrode 116 and the feed plate 102 to define a generally ring-shaped discharge gap 120 for generating a plasma therein. When activated, the discharge gap 120 can generate a discharge current between a side of the return electrode 116 and a side of the feed plate 102, the discharge current being adapted to flow generally parallel to the central longitudinal axis A and perpendicular to the side. In some embodiments, the separating dielectric member 122 is positioned next to the feed plate 102 along the longitudinal axis A, such that the feed plate 102 is sandwiched between the spacer 114 / discharge gap 120 on one side and the separating dielectric member 122 on the opposite side. In this stacked arrangement, the inner diameters of the stacked components are concentric and share the same central longitudinal axis A.

[0030] In some embodiments, for example, when a higher-power system is required, multiple discharge sections 104 can be assembled and stacked along the central longitudinal axis A within the plasma source 100. In an exemplary stacked arrangement of multiple discharge sections 104, an end component of one discharge section 104 can be shared with another discharge section 104. For example, as shown in FIG. 1c, a separating dielectric member 122 can be used by both discharge sections 104a and 104b, meaning that the discharge sections 104a and 104b are stacked back-to-back. In addition, the intermediate return electrode 116 can be shared by the two discharge sections 104b and 104c. Generally, the multiple discharge sections 104 form respective ones of the discontinuous discharge gaps 120 along the central longitudinal axis A to generate respective ones of the discharge currents used to dissociate the input gas, thereby generating local plasma within each discharge gap 120.

[0031] Further, in step 310, the input port 106 and the output port 108 are disposed at the ends of the plasma source 100, and the discharge section 104 extends along the central longitudinal axis A between the two ports 106, 108. The ports 106, 108 may be suitably configured to connect the plasma source 100 between two pump line segments such that the plasma source 100 is part of the overall pump line. Furthermore, each of the input port 106 and the output port 108 may function as a return electrode 116 for the discharge section 104.

[0032] The plasma source configuration 100 described above with reference to Figures 1a-1c, 2, and 3 is merely exemplary. Changes in form and detail may be made without departing from the spirit and scope of the present invention. In one example, the components designated as the supply electrode and return electrode in the plasma source 100 can be reversed in polarity so that the supply electrode can function as the return electrode (when the return electrode is electrically floating), and vice versa, while still maintaining substantially the same plasma generation capabilities. In some embodiments, the stacked components of the plasma source 100 are joined by co-firing techniques. For example, the barrier dielectric material and / or the isolation dielectric material may be ceramic and formed in the "green state" (e.g., at room temperature). At least one high-temperature metal element having a thermal expansion coefficient similar to the ceramic material of the barrier dielectric and / or isolation dielectric can then be patterned onto the ceramic material. The high-temperature metal can function as the supply electrode 204 of the embedded electrode assembly. The resulting structure is pressed and co-fired at a high temperature, e.g., about 1550°C to about 2000°C, to form a monolithic structure. In some embodiments, the stacked components are joined by gluing, for example, using Ablestik® 563 epoxy. In some embodiments, an O-ring seal 132 (as shown in FIG. 1 a) is used to seal the spacer 114 to the return electrode 116 when assembling the discharge section 104. In some embodiments, a load structure 170 is provided for axial compression of the stacked plasma source 100, including providing appropriate compression of the O-ring seal 132, as shown in FIG. 1 c. For example, the load structure 170 can be a bolted configuration using one or more bolts 170 a and springs and / or spring washers 170 b to ensure consistent mechanical compression.

[0033] 4a, 4b, and 4c show cross-sectional, external, and exploded views, respectively, of another exemplary plasma source 400 according to some embodiments of the present invention. Generally, the plasma source 400 has substantially the same function and configuration as the plasma source 100 of FIGS. 1a-1c, but has fewer individual components to assemble to form the resulting plasma source structure. As shown in FIG. 4b, the plasma source 400 generally includes a plasma source body 402 made from a non-conductive material such as a ceramic material (e.g., aluminum oxide or aluminum nitride), a stack of electrode plates 404 made from a conductive material such as copper, and an interconnecting printed circuit board (PCB) 406.

[0034] The plasma source body 402 generally encapsulates multiple non-conductive (e.g., ceramic) components of the plasma source 100 of FIGS. 1a-1c into one monolithic structure. For example, instead of having separate and distinct return electrode 116, spacer 114, barrier dielectric member 202, and isolation dielectric member 122, which may all be non-conductive, these are formed into a single structure. FIG. 5 shows an exemplary configuration of the body 402 of the plasma source 400 of FIGS. 4a-4c, according to some embodiments of the present invention. As shown, the plasma source body 402 defines a monolithic structure extending along a central longitudinal axis B between an input port 408 and an output port 410. In some embodiments, the input port 408 and the output port 410 have substantially the same configuration and function as the input port 106 and the output port 108, respectively, of the plasma source 100 of FIGS. 1a-1b. Similar to plasma source 100 , the plasma source body 402 of plasma source 400 defines one or more discharge sections 412 extending longitudinally between an input port 408 and an output port 410 .

[0035] In some embodiments, each discharge section 412 includes an external slot 414 disposed inwardly of the plasma source body 402 and recessed relative to the outer surface of the plasma source body 402. The external slot 414 may be ring-shaped and oriented perpendicular to the longitudinal axis B. The external slot 414 is configured to receive a pair of electrode plates 404, each having a half-ring shape with an outwardly extending flange 405. Thus, the two electrode plates 404 are configured to fit into each external slot 414 to form a complete ring-shaped supply electrode within the corresponding slot 414. The extending flanges 405 of the two electrode plates 404 are adapted to extend outward from the outer surface of the plasma source body 402, and the flanges 405 of the pair of electrode plates 404 are configured to receive a voltage from an external power source (not shown). The combination of (i) the electrode plate 405 and (ii) the non-conductive dielectric material of the body 402 that defines the slot 414 and surrounds the electrode plate 404 forms an embedded electrode assembly similar to the embedded electrode assembly in the discharge section 104 of the plasma source 100 described above with reference to Figures 1a-1c. More specifically, this combination is equivalent to the feed plate 102 and one or more separating dielectric members 122 adjacent to the feed plate 102 in the plasma source 100. In some embodiments, instead of using two half-ring electrode plates 404 to form one complete ring-shaped feed electrode, a single ring-shaped electrode plate is used.

[0036] In some embodiments, each discharge section 412 of the plasma source body 402 further includes an internal slot 416 disposed within the plasma source body 402 and recessed relative to the inner surface of the plasma source body 402. The internal slot 416 may be ring-shaped and may be oriented perpendicular to the longitudinal axis B. The internal slot 416 is disposed adjacent (e.g., next to) the external slot 414 along the longitudinal axis B within the discharge section 412. Each internal slot 416 defines a ring-shaped discharge gap substantially similar to the discharge gap 120 of the plasma source 100 of FIGS. 1a-1c. More specifically, the vertical wall sections 416a of the internal slots 416 that laterally bound the discharge gap may be equivalent to one or more spacers 114 of the plasma source 100. The discharge gap is also longitudinally bounded between (i) a sidewall section 416b of the internal slot 416, which may correspond to the return electrode 116 of the plasma source 100, and (ii) another sidewall section 416c of the internal slot 416, which may correspond to a portion of the feed plate 102 of the plasma source 100. Similar to the discharge gap 120 of the plasma source 100, a discharge current can be formed in the discharge gap 416 between the sidewalls 416b, 416c. The discharge current is adapted to flow parallel to the central longitudinal axis B and perpendicular to the sidewalls 416b, 416c. The current density associated with this discharge current is substantially uniform around the central longitudinal axis B.

[0037] In some embodiments, the plasma source body 402, together with the electrode plates 404, define multiple discharge sections 412 within the plasma source 400. An interconnection PCB 406 of the plasma source 400, disposed adjacent to the plasma source body 402, can be configured to electrically interconnect the flanges 405 of the electrode plates 404 of the discharge sections 412. More specifically, the interconnection PCB 406 can be in electrical communication with a power source (not shown) and can be configured to provide the same voltage to all of the interconnected electrode plates 404 via their respective flanges 405. In some embodiments, the plasma source body 402 is electrically grounded.

[0038] To assemble the plasma source 400, first, the electrode plates 404 are inserted into their respective external slots 414 in the plasma source body 402. After the electrode plates 404 are placed in place (e.g., secured with potting material), the flanges 405 of the electrode plates 404 are appropriately attached to the interconnect PCB 406. To operate the discharge section 412 of the plasma source 400, a voltage is applied to the electrode plates 404 via the interconnect PCB 406, which generates a discharge current in the discharge gap 416 (i.e., internal slot) of the plasma source body 402, which is adapted to dissociate an input gas supplied to the plasma source 400 via the input port 408.

[0039] In another aspect, the plasma sources described herein can form an in-line connection with one or more pump line segments within a semiconductor processing system, with each in-line plasma source providing an internal volume through which gas from the pump line can flow without changing the pumping speed and / or conductance along the pump line. A localized plasma can be formed within one or more discontinuous discharge gaps within the internal volume of each plasma source to dissociate the gas flow therein. Figure 6 illustrates an exemplary gas flow pattern maintained within the internal volume of the plasma source 100 of Figures 1a-1c, according to some embodiments of the present invention. While Figure 6 is described with respect to the plasma source 100 of Figures 1a-1c, substantially the same flow pattern can be maintained within the internal volume of the stacked plasma source 400 of Figures 4a-4c. As shown, a gas flow 600 is supplied to the input port 106 of the plasma source 100. A significant portion 608 of the gas flow 600 travels from the input port 106 to the output port 108 through an open, high-conductance central region 602 within the internal volume of the plasma source 100. However, diffusion and turbulent mixing can occur within the internal volume of the plasma source 100, causing non-dissociated gas 604 to move from the central flow region 602 into the discharge gap 120 of the plasma source 100, where it dissociates. This mixing can also cause dissociated atomic radicals 606 to move from the discharge gap 120 into the central flow region 602 and be carried to the output port 108. Such mixing and dissociation can occur in all discharge gaps 120 in the stacked configuration of the plasma source 100. In some embodiments, the plasma sources described herein can be used to clean CVD systems, where one or more of the plasma sources are located downstream from a processing chamber and coupled in-line with a pump line. In some embodiments, the plasma sources described herein are compatible with the cleaning systems and methods described in U.S. Patent Application No. 17 / 107,146, which is owned by the assignee of the present application and is incorporated by reference in its entirety.

[0040] While the present invention has been particularly shown and described with reference to specific embodiments, it will be understood by those skilled in the art that various changes in form and details can be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. 1. A plasma source comprising: a body defining an input port, an output port, and at least one discharge section extending along a central longitudinal axis between the input port and the output port; The at least one discharge section comprises: a return electrode defining a first generally cylindrical interior volume having a first inner diameter disposed perpendicular to the central longitudinal axis; a feed plate including a feed electrode, the feed plate defining a second generally cylindrical interior volume having a second inner diameter disposed perpendicular to the central longitudinal axis; at least one spacer defining a third generally cylindrical internal volume having a third inner diameter disposed perpendicular to the central longitudinal axis, the third inner diameter being larger than the first inner diameter and the second inner diameter such that a portion of the internal volume of the at least one spacer is recessed laterally relative to the return electrode and the supply electrode; the at least one discharge section is formed from the at least one spacer disposed along the central longitudinal axis between the return electrode and the supply plate to define a ring-shaped discharge gap for generating plasma therein, the discharge gap being disposed in the recessed portion of the internal volume of the at least one spacer, the first internal volume, the second internal volume, and the third internal volume sharing the same central longitudinal axis in the at least one discharge section; The plasma source, wherein the feeder plate further comprises at least one dielectric member laterally surrounding the feeder electrode.

2. The plasma source of claim 1 , wherein the return electrode is electrically grounded.

3. The plasma source of claim 1 , wherein the at least one dielectric member of the feeder plate is a ring-shaped barrier dielectric member configured to laterally surround a ring-shaped feeder electrode.

4. 10. The plasma source of claim 1, wherein the at least one discharge section further comprises a ring-shaped separating dielectric member positioned adjacent the feeder plate along the central longitudinal axis.

5. The plasma source of claim 1 , wherein the first inner diameter of the return electrode and the second inner diameter of the feeder plate are substantially the same.

6. The plasma source of claim 1 , wherein the discharge gap is bounded longitudinally between a side of the return electrode and a side of the feeder plate and is bounded laterally by the at least one spacer.

7. 7. The plasma source of claim 6, wherein a discharge current is formed in the discharge gap between the side of the return electrode and the side of the supply plate, the discharge current adapted to flow parallel to the central longitudinal axis and perpendicular to the side.

8. The plasma source of claim 7 , wherein the current density of the discharge current is substantially uniform around the central longitudinal axis.

9. The plasma source of claim 1 , wherein the at least one spacer of the discharge section comprises a plurality of spacers joined along the central longitudinal axis.

10. The plasma source of claim 1 , wherein the body of the plasma source comprises a plurality of discharge sections arranged along the central longitudinal axis.

11. The plasma source of claim 10 , wherein the plurality of discharge sections form a plurality of discontinuous discharge gaps along the central longitudinal axis for generating respective plasmas.

12. The plasma source of claim 11 , wherein the plurality of discontinuous discharge gaps are substantially uniform.

13. The plasma source of claim 1 , wherein at least one of the return electrode, the feeder plate, or the at least one spacer is formed by one of co-firing or bonding.

14. The plasma source of claim 1 , wherein the at least one spacer is made from a non-conductive material.

15. 1. A method of manufacturing a plasma source, comprising: Assembling at least one discharge section, providing a return electrode defining a first generally cylindrical interior volume having a first inner diameter disposed perpendicular to a central longitudinal axis; providing a feed plate including a feed electrode, the feed plate defining a second generally cylindrical interior volume having a second inner diameter disposed perpendicular to the central longitudinal axis; providing at least one spacer defining a third generally cylindrical interior volume having a third inner diameter disposed perpendicular to the central longitudinal axis, the third inner diameter being larger than the first inner diameter and the second inner diameter such that a portion of the interior volume of the at least one spacer is recessed transversely relative to the return electrode and the supply electrode; disposing the spacer along the central longitudinal axis between the return electrode and the feeder plate to define a ring-shaped discharge gap for generating plasma therein, the discharge gap being disposed in the recessed portion of the internal volume of the at least one spacer, and the first internal volume, the second internal volume, and the third internal volume sharing the same central longitudinal axis in the at least one discharge section; assembling at least one discharge section, forming a body comprising an input port, an output port, and the at least one discharge section extending along the central longitudinal axis between the input port and the output port; The method of manufacturing a plasma source, wherein the feeder plate further comprises at least one dielectric member laterally surrounding the feeder electrode.

16. 16. The method of claim 15, further comprising electrically grounding the return electrode.

17. 16. The method of claim 15, wherein assembling the at least one discharge section further comprises providing a ring-shaped isolating dielectric member and disposing the isolating dielectric member adjacent the feeder plate along the central longitudinal axis.

18. 16. The method of claim 15, wherein the discharge gap is bounded longitudinally between a side of the return electrode and a side of the feeder plate and is bounded laterally by the spacer.

19. generating a discharge current in the discharge gap between the side of the return electrode and the side of the feeder plate; directing the discharge current generally parallel to the central longitudinal axis and perpendicular to the side surfaces; 20. The method of claim 18, further comprising:

20. 20. The method of claim 19, wherein the density of the discharge current is substantially uniform around the central longitudinal axis.

21. assembling a plurality of discharge sections; disposing the plurality of discharge sections along the central longitudinal axis between the input port and the output port to form the body of the plasma source; 16. The method of claim 15, further comprising:

22. 22. The method of claim 21, further comprising forming a plurality of discontinuous discharge gaps with the plurality of discharge sections along the central longitudinal axis for generating respective plasmas.

23. 16. The method of claim 15, further comprising forming at least one of the return electrode, the supply plate, or the at least one spacer by one of co-firing or bonding to assemble the at least one discharge section.

24. The method of claim 15 , wherein the spacer is made from a non-conductive material.

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