Plasma processing system and method for operating a plasma processing system - Patents.com

Abstract

To provide a plasma processing system and a method for operating the plasma processing system.SOLUTION: A plasma processing system includes: a plasma assembly comprising a plasma chamber defining a plasma channel, the plasma chamber having two dielectric portions composed of a dielectric material and a bonding interface that bonds the two dielectric portions along a bonding surface to form a hermetic seal between the two dielectric portions; and a heat sink substantially surrounding the plasma chamber, the heat sink being divided along a coupling surface into two conductive portions, the two conductive portions being composed of a conductive material and electrically isolated from each other; and a power transformer including a magnetic core, a primary coil, and the plasma assembly, the power transformer being configured to induce an electric field that ionizes gas in the plasma channel of the plasma chamber.SELECTED DRAWING: Figure 8A

Description

[Technical field]

[0001] The present invention relates generally to the field of plasma generation and processing equipment, and more specifically to an apparatus and method for plasma generation and processing with improved resistance to plasma chemistries and contamination. [Background technology]

[0002] Plasma discharges can be used to excite gases to produce activated gases, which contain ions, free radicals, atoms, and molecules. Activated gases are used in many industrial and scientific applications, including the processing of solid materials such as semiconductor wafers, powders, and other gases. The parameters of the plasma and the conditions of exposure of the plasma to the material being processed vary widely depending on the application.

[0003] For example, some applications require the use of ions with low kinetic energies (i.e., a few electron volts) because the materials being processed are susceptible to damage. Other applications, such as anisotropic etching and planarized dielectric deposition, require the use of ions with high kinetic energies. Still other applications, such as reactive ion beam etching, require precise control of ion energy.

[0004] Some applications require the material being processed to be directly exposed to a high density plasma. One such application is to generate ion-activated chemical reactions. Other applications include etching and depositing materials into high aspect ratio structures. Other applications require the material being processed to be shielded from the plasma because the material is susceptible to damage by ions or because the process has high selectivity requirements.

[0005] Plasma can be created in a variety of ways, including direct current (DC), radio frequency (RF), and microwave discharges. DC discharges are achieved by applying an electrical potential between two electrodes in a gas. RF discharges are achieved by capacitively or inductively coupling energy from a power source into the plasma. Microwave discharges can be created by coupling a microwave energy source into a discharge chamber containing a gas.

[0006] The plasma discharge can be generated in such a way that both the charged species that make up the plasma and the neutral species that can be activated by the plasma are in intimate contact with the material being processed. Alternatively, the plasma discharge can be generated remotely from the material being processed, so that a relatively small number of charged species are in contact with the material being processed, while neutral species can still be in contact with the material being processed. Such plasma discharges are commonly referred to as remote or downstream plasma discharges. Depending on its structure, its relative placement with respect to the material being processed, and the operating conditions (e.g., gas species, pressure, flow rate, and power coupled to the plasma), a plasma source can have characteristics of either or both of these two general types.

[0007] Existing remote plasma sources generally utilize RF or microwave power to generate plasma. Although current remote plasma sources successfully support many applications, several technical limitations remain in the practical use of these remote plasma sources. For example, microwave-based remote plasma sources are generally more expensive than RF sources because microwave power is generally expensive to generate, deliver, and match to a load. Microwave sources and power delivery systems are also generally bulkier than RF sources, and the tubes that generate the microwave power require periodic replacement.

[0008] RF remote plasma sources with some degree of capacitive and inductive coupling may be less expensive and smaller than corresponding microwave sources. However, the capacitive coupling that aids in the plasma ignition process may result in degradation of the exposed walls of the plasma chamber due to bombardment of the exposed walls by energetic ions generated in the plasma. RF remote plasma sources that utilize inductive RF coupling but minimize the associated capacitive coupling may experience less ion-induced degradation of the plasma vessel surface. However, the reduction or elimination of capacitive coupling may make plasma ignition more difficult to obtain, especially over a wide range of process conditions.

[0009] A second difficulty with existing remote plasma sources is the removal of heat generated in the plasma and deposited on the walls of the plasma chamber. This is especially true when the plasma chamber has a complex geometry and / or is constructed from a dielectric material where direct cooling by a large volume of fluid in contact with the dielectric plasma chamber is undesirable or impractical. This has the effect of limiting the power that can be reliably coupled into the plasma.

[0010] Some existing plasma chambers, such as that described in U.S. Patent No. 5,399,633, are fabricated using quartz material using a combination of high temperature forming and welding to produce the desired shape (e.g., a torus shape). The main drawback of quartz plasma chambers is their incompatibility with hydrogen and / or halogen plasma chemistries, such as hydrogen (H*), fluoride (F*) and / or chlorine (Cl*), due to the rapid rate of chemical and physical erosion of quartz when exposed to these chemicals.

[0011] Additionally, some existing plasma chambers, such as those described in (Patent Document 2), are manufactured by machining a plasma block from aluminum, where the plasma blocks are connected to form a plasma channel of the desired shape (e.g., a torus shape). The inner surface of the plasma channel is coated using either a deposition process (e.g., chemical vapor deposition, physical vapor deposition, or plasma spray) or a conversion process (e.g., hard anodization) to form a dielectric barrier between the base material and the plasma. One drawback of plasma chambers made with aluminum plasma blocks with a dielectric coating is that the coating is thin, usually on the order of a few micrometers to tens of micrometers, and therefore cannot withstand the high plasma ignition voltage required to ignite the in-process gas due to electrical breakdown of the dielectric coating. An inert gas such as argon can be used as the ignition gas to reduce the ignition voltage, but the transition from the ignition gas to the process gas creates a time delay, reducing throughput in pulsed plasma applications. Another drawback of thin coatings is that they do not adequately protect the plasma chamber body if defects in the coating expose the underlying aluminum to the reactive gases in the plasma chamber. Additionally, for conversion coatings, such as those using hard anodizing, the purity of the coating directly exposed to the plasma depends on the purity of the base aluminum alloy. For example, 6061 aluminum has an aluminum content of 95.8-98.6%, with the remainder being other metal alloying elements. These other metallic impurities can be a potential source of contamination in semiconductor processing. Also, many machined plasma channel geometries have deep holes with aspect ratios (ratio of length to diameter) ranging from 2:1 to 10:1. Such high aspect ratio holes are not practical to coat using physical vapor deposition (PVD) or plasma spray methods because these coatings are applied from an open end and can be much thinner than the coating thickness required in hard-to-reach areas. High aspect ratio holes can be conformally coated using other deposition processes such as chemical vapor deposition (CVD) or atomic layer deposition (ALD).However, the deposition rates of CVD and ALD are much lower than those of spray coating, making these deposition processes slow and prohibitively expensive.

[0012] Furthermore, some existing plasma chambers, such as that described in (Patent Document 3), are formed by connecting multiple generally linear dielectric tubes to achieve a desired shape (e.g., a torus shape). While the use of generally linear tubes as building blocks for plasma chambers expands the range of available materials, the main drawback is the increased manufacturing complexity and cost. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] U.S. Pat. No. 7,659,489 [Patent Document 2] U.S. Patent No. 7,166,816 [Patent Document 3] U.S. Patent No. 8,053,700 Summary of the Invention [Problem to be solved by the invention]

[0014] There is a need for plasma chambers that have improved resistance to certain plasma chemistries, such as hydrogen and / or halogen plasma chemistries, while minimizing metal contamination in semiconductor processing. There is also a need for plasma chambers that can be manufactured with reduced complexity and cost. [Means for solving the problem]

[0015] The present invention provides thick-walled plasma chambers capable of igniting in-process gases, and such plasma chambers can be fabricated from high-purity dielectric materials that are compatible with plasma chemistries (e.g., have low erosion rates), such as hydrogen and / or halogen plasma chemistries. High-purity dielectric materials can also minimize metal contamination in semiconductor processing. High-purity dielectric materials also provide improved thermomechanical properties.

[0016] In one aspect, a plasma chamber of a plasma processing system is provided. The plasma chamber defines a plasma channel, the plasma channel having a first side and a second side disposed on opposite sides along its length. The plasma chamber includes a first portion constructed from a dielectric material. The first portion has (i) a first flange disposed along the first side of the plasma channel and extending beyond the first side by a first width, and (ii) a second flange disposed along the second side of the plasma channel and extending beyond the second side by a second width. The plasma chamber includes a second portion constructed from a dielectric material. The second portion has (i) a third flange disposed along the first side of the plasma channel and extending beyond the first side by the first width, and (ii) a fourth flange disposed along the second side of the plasma channel and extending beyond the second side by a second width. The plasma chamber further includes interfaces coupling the first portion and the second portion between the first flange and the third flange and between the second flange and the fourth flange.

[0017] In another aspect, a method of fabricating a plasma chamber of a plasma processing system is provided. The plasma chamber defines a plasma channel, the plasma channel having a first side and a second side disposed oppositely along a length thereof. The method includes constructing a first portion from a dielectric material. The first portion has (i) a first flange disposed along the first side of the plasma channel and extending beyond the first side by a first width, and (ii) a second flange disposed along the second side of the plasma channel and extending beyond the second side by a second width. The method also includes constructing a second portion from a dielectric material. The second portion has (i) a third flange disposed along the first side of the plasma channel and extending beyond the first side by the first width, and (ii) a fourth flange disposed along the second side of the plasma channel and extending beyond the second side by a second width. The method further includes coupling the first portion and the second portion to form a plasma chamber having a plasma channel for containing a plasma therein. Joining the first and second portions includes forming a bond between the first flange and a third flange to generate a first joining flange having a first width, and forming a bond between the second flange and a fourth flange to generate a second joining flange having a second width.

[0018] Any of the above aspects can include one or more of the following features: In some embodiments, the dielectric material is an alumina (Al2O3) ceramic. In some embodiments, the dielectric material is an oxide or nitride of one of Group II elements, Group III elements, lanthanides, or mixtures thereof. In some embodiments, the dielectric material is one of Y2O3, Sc2O3, La2O3, Ce2O3, or MgO. In some embodiments, the dielectric material is one of AlN, BN, or YN.

[0019] In some embodiments, the coating is disposed on an interior surface of the plasma chamber and forms at least a portion of a plasma channel exposed to the plasma in the plasma chamber. The coating can include any of Al2O3, YO3, Sc2O3, La2O3, Ce2O3, MgO, SiO2, B4C, or an alloy including YAG.

[0020] In some embodiments, the first and second portions are substantially identical. In some embodiments, the wall thickness of the first or second portion is about 0.04 inches to about 0.12 inches. In some embodiments, the first or second portion is constructed by machining a dielectric material in the green state.

[0021] In some embodiments, the plasma chamber further includes (i) a first mating flange formed by mating the first flange and the third flange, the first mating flange having a first width, and (ii) a second mating flange formed by mating the second flange and the fourth flange, the second mating flange having a second width. In some embodiments, the first width of the first mating flange or the second width of the second mating flange is about 0.06 inches to about 1 inch. For example, the first width or the second width may be about 0.25 inches.

[0022] In some embodiments, the bonding interface includes a bonding agent that is one of a glass frit, a eutectic, or an epoxy. For example, the eutectic can include one or more of Al2O3, Y2O3, Sc2O3, Ce2O3, MgO, CaO, or ZrO2. In some embodiments, the first and second parts are bonded together by sintering the first and second parts together to create a hermetic seal at the first and second bonding flanges. In some embodiments, a layer of alloying agent can be disposed on an inner surface of at least one of the first or second parts prior to sintering. The inner surface is adapted to form at least a portion of the plasma channel that is exposed to the plasma in the plasma channel. An alloy coating is created on at least a portion of the inner surface having a layer of alloying agent disposed thereon by a sintering process that bonds the first and second parts.

[0023] In some embodiments, the plasma channel forms a toroidal loop. The toroidal plasma channel can be circular, elliptical, oval, or polygonal in shape. In some embodiments, the plasma channel is linear. In some embodiments, the cross-section of the plasma channel is circular, rectangular, or elliptical. The cross-sectional area of ​​the plasma channel is about 0.2 cm 2 ~about 50cm 2 may be also possible.

[0024] The advantages of the present invention described above, 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 being placed upon illustrating the principles of technology, in which: [Brief description of the drawings]

[0025] [Figure 1] 1 illustrates an exemplary plasma chamber according to some embodiments of the present invention. [Diagram 2]2 illustrates an exemplary assembly for forming the plasma chamber of FIG. 1 according to some embodiments of the present invention. [Diagram 3] 1 illustrates a toroidal plasma chamber having a rectangular toroidal plasma channel, according to some embodiments of the present invention. [Figure 4] 1 illustrates a toroidal plasma chamber having an elliptical toroidal plasma channel according to some embodiments of the present invention. [Diagram 5] 1 illustrates a portion of a toroidal plasma chamber having a plasma channel with a rectangular inner profile and a rectangular outer profile cross-section, according to some embodiments of the present invention. [Figure 6] 1 illustrates a portion of a toroidal plasma chamber having a plasma channel with a cross-section of a circular inner profile and a circular outer profile, according to some embodiments of the present invention. [Figure 7] 1 illustrates a portion of a toroidal plasma chamber having a plasma channel with a cross-section of a circular inner profile and a hexagonal outer profile, according to some embodiments of the present invention. [Figure 8A] 2 illustrates an exemplary plasma processing system including the plasma chamber of FIG. 1, in accordance with some embodiments of the present invention. [Figure 8B] 2 shows a cutaway view of an exemplary plasma processing system including the plasma chamber of FIG. 1 in accordance with some embodiments of the present invention. [Figure 8C] 2 shows a side view of an exemplary plasma processing system including the plasma chamber of FIG. 1 in accordance with some embodiments of the present invention. [Figure 9] 8D shows a cross-sectional view of the plasma processing system of FIG. 8C according to some embodiments of the present invention. [Figure 10] 8D illustrates another cross-sectional view of the plasma processing system of FIG. 8C with an electrically isolated heat sink section according to some embodiments of the present invention. [Figure 11] 1 illustrates a cross-sectional view of an assembly including a plasma chamber encapsulated by a heat sink section according to some embodiments of the present invention. [Figure 12a] 2 illustrates a simulated temperature profile of the plasma chamber of FIG. 1 having first and second mating flanges in accordance with some embodiments of the present invention. [Figure 12b] 1 illustrates a simulated temperature profile of a plasma chamber without first and second mating flanges in accordance with some embodiments of the present invention. [Figure 13] 2 illustrates an exemplary process for manufacturing the plasma chamber of FIG. 1 according to some embodiments of the present invention. [Figure 14a] 1 illustrates an exemplary plasma chamber according to some embodiments of the present invention. [Figure 14b] 1 illustrates an exemplary plasma chamber according to some embodiments of the present invention. [Figure 14c] 1 illustrates an exemplary plasma chamber according to some embodiments of the present invention. [Figure 15a] 8A-8C illustrate an exemplary pulsed operation using the plasma processing system illustrated in FIGS. 8A-8C as a remote plasma source according to some embodiments of the present invention. [Figure 15b] 8A-8C illustrate an exemplary pulsed operation using the plasma processing system illustrated in FIGS. 8A-8C as a remote plasma source according to some embodiments of the present invention. [Figure 15c] 8A-8C illustrate an exemplary pulsed operation using the plasma processing system illustrated in FIGS. 8A-8C as a remote plasma source according to some embodiments of the present invention. [Figure 15d] 8A-8C illustrate an exemplary pulsed operation using the plasma processing system illustrated in FIGS. 8A-8C as a remote plasma source according to some embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] FIG. 1 illustrates an exemplary plasma chamber 100 according to some embodiments of the present invention. In general, a plasma chamber is a vessel or portion of a vessel that contains gas and / or plasma, within which the plasma can be ignited and / or maintained. The plasma chamber is adapted to be combined with other components, such as power generation and cooling components, to form a plasma processing system. The plasma chamber typically defines one or more plasma channels having various shapes. For example, the plasma channel can have a linear shape or a loop shape (e.g., to support a toroidal plasma). As shown in FIG. 1, the plasma chamber 100 may be a toroidal loop, which is defined as forming a loop internal plasma channel (not shown) with a closed path to maintain plasma current circulation in the closed path.

[0027] A plasma chamber 100 including a plasma channel has a first side 102 and a second side 104 disposed on opposite sides along the length of the plasma channel. The plasma chamber 100 also includes a first mating flange 110 extending from the first side 102 by a first width. The plasma chamber 100 further includes a second mating flange 112 extending from the second side 102 by a second width. Specifically, for the circular toroidal plasma chamber 100 shown in FIG. 1, the first mating flange 110 extends inwardly from the first side / inner side 102 by a first width, and the second mating flange 112 extends outwardly from the second side / outer side 104 by a second width. In general, the dimensions of the circular toroidal plasma chamber 100, such as the inner radius (i.e., from the center of the circular toroidal plasma chamber 100 to the first side 102) and the outer radius (i.e., from the center of the circular toroidal plasma chamber 100 to the second side 104), are defined based on the required flow rate of process gas in the plasma channel and the required plasma power. In some embodiments, the outer radius of the circular toroidal plasma chamber 100 is about 6 inches.

[0028] Figure 2 illustrates an exemplary assembly for forming the plasma chamber 100 of Figure 1, according to some embodiments of the present invention. The plasma chamber 100 is composed of several separate parts, including a first part 204 that forms the bottom half of the plasma chamber 100, a second part 206 that forms the top half of the plasma chamber 100, and a coupling interface 207 (shown in Figure 1) that couples the first and second parts 204, 206 of the plasma chamber 100. The first and second parts 204, 206 and the coupling interface 207 can be composed of the same dielectric material or two or more different dielectric materials.

[0029] As shown, the first portion 204 defines (i) a first wall portion 208 having an inner surface that defines a portion of the plasma channel, (ii) a first flange 210 disposed along the first side 102 of the plasma channel and extending beyond the first side 102 by a first width, and (iii) a second flange 212 disposed along the second side 104 of the plasma channel and extending beyond the second side 104 by a second width. Similarly, the second portion 206 defines (i) a second wall portion 210 having an inner surface that defines another portion of the plasma channel, (ii) a third flange 216 disposed along the first side 102 of the plasma channel and extending beyond the first side by a first width, and (iii) a fourth flange 218 disposed along the second side 104 of the plasma channel and extending beyond the second side 104 by a second width. The bonding interface 207 is formed by bonding the first and second portions 204, 206 between the first and third flanges 210, 216 and between the second and fourth flanges 212, 218 of the first and second portions 204, 206, respectively. Specifically, the bonding at the bonding interface 207 is adapted to form the plasma chamber 100 as a monolithic structure, the monolithic structure including (i) the first and second wall portions 208, 214 cooperatively defining a plasma channel for containing gas and / or plasma therein, (ii) the first and third flanges 210, 216 cooperatively defining a first bonding flange 110 having a first width, and (iii) the second and fourth flanges 212, 218 cooperatively defining a second bonding flange 112 having a second width. In some embodiments, the first width of the first mating flange 110 and / or the second width of the second mating flange 112 is between about 0.06 inches and about 1 inch. For example, the first width and the second width may be about 0.25 inches.

[0030] In general, the bond strength for forming the first bonding flange 110 or the second bonding flange 112 at the bonding interface 207 is proportional to the amount of surface area at the bonding interface 207. In the absence of the bonding flanges 110, 112, the relatively thin first wall portion 208 and / or second wall portion 210 of the plasma chamber 100 are adapted to create a thin bonding interface 207 that may compromise the reliability of the bond, even though the thin wall is beneficial for reducing thermal stress. Thus, the first bonding flange 110 and the second bonding flange 112 are used to ensure a more reliable and robust bond between the first portion 204 and the second portion 206 of the plasma chamber 100. This is advantageous in that it allows the thicknesses of the first wall portion 208 and the second wall portion 210 to be independently optimized for minimizing thermomechanical stress.

[0031] In some embodiments, the first and second portions 204, 206 of the plasma chamber 100 are substantially identical. In some embodiments, each of the first and second portions 204, 206 of the plasma chamber 100 is formed from a dielectric material and machined in the green state. These two portions 204, 206 of the plasma chamber 100 can be bonded by any of the following bonding approaches, which include (i) applying and fusing glass frits at the flanges 210, 212, 216, 218 to form a glass bond at the bonded flanges 110, 112; (ii) applying a metal such as Al2O3, Y2O3, Sc2O3, Ce2O3, MgO, CaO, or a combination of metals such as SiO2, SiO2, SiO3, MgO, CaO, or a combination of metals such as SiO2, SiO2, SiO3, MgO, CaO, or a combination of metals such as SiO2, SiO2, SiO2, MgO, CaO, or a combination of metals such as SiO2, SiO2, MgO, CaO, or a combination of metals such as SiO2, MgO, CaO, Mg ... or ZrO2 to sinter the two portions 204, 206 together to form the joined flanges 110, 112, (iii) co-firing the two portions 204, 206 to form the joined flanges 110, 112, or (iv) applying a high temperature epoxy to the flanges 210, 212, 216, 218 to cure the two portions 204, 206 to form the joined flanges 110, 112. A strong airtight seal can be formed in the joined flanges 110, 112.

[0032] As mentioned above, the plasma chamber 100 including the first and second portions 204, 206 can be made from the same or different dielectric materials. Typically, the resistance of a particular material to plasma is measured in terms of its etch rate (e.g., the rate of material removal per unit time measured in micrometers / minute). In some embodiments, the dielectric material used to construct the plasma chamber 100 is a high purity (e.g., about 99.5% to about 99.9%) alumina (Al2O3) ceramic material selected for its low etch rate in halogen plasma. In addition, alumina exhibits excellent thermal shock resistance, which is another important parameter for material selection for thermal stress applications. The equation for thermal shock resistance is shown in Equation [1]:

[0033]

number

[0034] where R is the thermal shock resistance, σF is the bending strength of the material (MPa), v is the Poisson's ratio, K is the thermal conductivity (W / mK), E is Young's modulus (GPa), and α is the thermal expansion coefficient (μm / mK). Equation [1] combines several material properties important for thermal stress resistance by producing a single number that indicates how well the material can withstand thermal stress. The higher the resistance value, the better the material can handle thermal stress. For example, quartz, the dielectric material used in some of the existing plasma chambers, has a thermal shock factor of about 2500. In contrast, alumina has a thermal shock resistance of about 3400, mainly due to a combination of its high strength and high thermal conductivity. Thus, from a thermal stress handling standpoint, alumina is about 1.4 times better as a structural material than quartz for building plasma chambers.

[0035] In some embodiments, the dielectric material for constructing the plasma chamber 100 is an oxide or nitride of one of group II elements, group III elements, lanthanides, or mixtures thereof. For example, the dielectric material may be one of Y2O3, Sc2O3, La2O3, Ce2O3, or MgO. As another example, the dielectric material may be one of AlN, BN, or YN.

[0036] In some embodiments, the plasma resistance of the plasma chamber 100 is improved by doping or alloying the dielectric material (Al2O3) with a small amount of an oxide of one of the group II or group III elements, such as Y2O3, Sc2O3, or MgO, to create the plasma chamber 100. When Al2O3 powder is mixed with a small amount of Y2O3, Sc2O3, or MgO powder and the mixture is heated to a temperature of about 1700° C., the Al x Y y O z , Al x Sc y O z , or Al x Mg y O z It has been found that stoichiometric alloys of the form Al2O3 are formed. Such alloys have been shown to have lower erosion rates when exposed to halogen plasma chemistries such as F*, Cl*, and Br* compared to Al2O3 alone.

[0037] In some embodiments, the coating is applied to the inner surface of the first wall portion 208 of the first portion 204 and / or the inner surface of the second wall portion 210 of the second portion 206 before the first portion 204 and the second portion 206 of the plasma chamber 100 are coupled at the coupling interface 207. As described above, the two wall portions 208, 214 are adapted to form a plasma channel that is exposed to the plasma therein. Thus, the coating can be applied to the inner surfaces of these two portions such that they directly face the plasma. The coating can include one or more of yttria (Y2O3), Sc2O3, La2O3, Ce2O3, MgO, SiO2, B4C, or YAG alloys, which have a lower etch rate in a halogen plasma compared to Al2O3. The coating can also include Al2O3. In general, thicker coatings will have a longer life than thinner coatings because they take longer to etch due to erosion. However, the adhesion of the coating to the plasma chamber surface is related to the thickness of the coating. As temperature changes, the mismatch in the thermal expansion coefficients of the coating and base materials creates thermomechanical stresses at the interface and coating material. Such stresses increase with temperature or temperature gradients and can cause failure of the coating. Optimal coating thicknesses range from 5 to 1000 μm for most of the coating materials listed above. In some embodiments, the preferred coating thickness is 10 to 100 μm.

[0038] In some embodiments, a coating process such as plasma or flame spray is used to deposit a dense coating of material on the inner surface of the first wall portion 208 and / or the inner surface of the second wall portion 214, where the thickness of the coating is on the order of a few microns to a few hundred microns. However, spray coating, also known as line-of-sight coating, requires that the coating surface be sufficiently exposed to achieve a relatively uniform coating thickness. As shown in FIG. 2, the piecewise structure of the plasma source 100 is particularly suitable for spray coating because the inner surfaces of the first wall portion 208 and the second wall portion 214, which form the resulting plasma channel of the plasma chamber 100, are easily accessible and sufficiently exposed prior to joining of the two portions 204, 206.

[0039] In an exemplary coating process, a thin layer of an alloying agent (e.g., Y2O3, Sc2O3, or MgO) is deposited on at least one inner surface of the first wall portion 208 of the first portion 204 or the second wall portion 210 of the second portion 206 after the two portions 204, 206 are machined in the green state and before the two portions 204, 206 are bonded together, as shown in Figure 2. When the two portions 204, 206 are bonded together at a bonding interface 207 using a desired bonding process (e.g., co-firing, sintering, etc.), the Al x Y y O z , Al x Sc y O z , or Al x Mg y O z A thin layer of an alloy coating, such as in the form of, is produced on at least a portion of the inner surface. In some embodiments, the same alloying agent (e.g., Y2O3, Sc2O3, or a mixture of Y2O3 and Al2O3) is also made into a slurry material and used as a bonding agent at the bonding interface 207 to eutectic bond the two portions 204, 206 to form the first and second bonding flanges 110, 112. The eutectic bond and the formation of the alloy coating can occur in the same bonding process.

[0040] In some embodiments, the thickness of the first wall portion 208 and / or the second wall portion 214 of the plasma chamber 100 is about 0.04 inches to about 0.12 inches. The main limitation of a dielectric plasma chamber (e.g., the plasma chamber 100) is the thermomechanical stress resulting from the plasma heat load. There are two competing factors that determine the optimal wall thickness in relation to the thermomechanical stress. On the one hand, the thinner the wall of the plasma chamber, the smaller the temperature gradient across the thickness of the wall. On the other hand, the wall of the plasma chamber needs to be thick enough to have sufficient mechanical strength to counter the thermal and other stresses that the plasma chamber experiences during assembly. Therefore, an optimal balance of these two factors (i.e., mechanical strength and low temperature gradients) is desired to reduce thermal stresses. The thickness of the first wall portion 208 and / or second wall portion 214 of the plasma chamber 100 can be selected to be between about 0.04 inches and about 0.12 inches to balance these two competing factors.

[0041] Although Figures 1 and 2 show the toroidal plasma chamber 100 having a toroidal plasma channel that is circular in overall shape, other toroidal channel shapes are possible, such as elliptical, oval, or polygonal. For example, Figure 3 shows a toroidal plasma chamber 300 having a toroidal plasma channel that is rectangular, according to some embodiments of the invention. Figure 4 shows a toroidal plasma chamber 400 having an elliptical toroidal plasma channel, according to some embodiments of the invention. The above characteristics and piecewise fabrication approach for the toroidal plasma chamber 100 are equally applicable to linear plasma chambers. For example, in an alternative embodiment, the plasma chamber of the invention is in the form of a linear plasma channel formed by the disclosed bonding process.

[0042] The cross-section of the plasma channel of the present invention can have different shapes, such as circular, elliptical, oval, polygonal, or rectangular / square. Furthermore, the outer and inner contours of the cross-section of the plasma channel may have the same or different shapes. For example, FIG. 5 shows a portion of a toroidal plasma chamber 500 having a plasma channel 502 with a rectangular inner contour 506 and a cross-section 504 with a rectangular outer contour 508, according to some embodiments of the present invention. FIG. 6 shows a portion of a toroidal plasma chamber 600 having a plasma channel 602 with a circular inner contour 606 and a cross-section 604 with a circular outer contour 608, according to some embodiments of the present invention. FIG. 7 shows a portion of a toroidal plasma chamber 700 having a plasma channel 702 with a circular inner contour 706 and a cross-section 704 with a hexagonal outer contour 708, according to some embodiments of the present invention. In some embodiments, the cross-sectional area of ​​the plasma channel is about 0.2 cm 2 ~about 50cm 2 may be also possible.

[0043] 8A-8C illustrate an exemplary plasma processing system 800, in accordance with some embodiments of the present invention. Figure 8A illustrates the exemplary plasma processing system 800 including the plasma chamber 100 of Figure 1. Figure 8B illustrates a cutaway view of the plasma processing system 800 of Figure 8A. Figure 8C illustrates a side view of the exemplary plasma processing system 800 of Figure 8A. As illustrated, the plasma processing system 800 includes the plasma chamber 100 having at least one gas inlet 806 and at least one gas outlet represented by an outlet flange 808.

[0044] The plasma chamber 100 is surrounded by a heat sink 810 for removing heat from the plasma chamber 100. The heat sink 810 can be formed from multiple sections, such as at least two sections 810a, 810b, that substantially surround the plasma chamber 100. The division of the heat sink 810 can aid in the assembly of the system 800, especially when the plasma chamber 100 has a complex shape, such as a toroidal shape. In some embodiments, the heat sink 810 is divided into two sections along an azimuthal plane (i.e., the XZ plane as shown in FIG. 8B). The resulting two heat sink sections 810a, 810b can be substantially identical and aligned along the y-axis to form the overall heat sink 810. In some embodiments, the heat sink 810 is formed as a single monolithic component.

[0045] The plasma processing system 800 includes a power transformer 822 that couples electromagnetic energy to the plasma chamber 100. The power transformer 822 includes a high permeability magnetic core 804, a primary coil 824, and the plasma chamber 100. The plasma chamber 100 allows the plasma to form a secondary circuit of the transformer 822. The magnetic core 804 can be supported and cooled by a support structure 818. The power transformer 822 can include additional magnetic cores and conductor coils that form additional primary or secondary circuits. For example, the system 800 shown in FIGS. 8A-8C shows the plasma chamber 100 surrounded by four transformer cores (e.g., the magnetic core 804 and three additional magnetic cores (not labeled)).

[0046] 9 shows a cross-sectional view of the plasma processing system 800 along the AA cross-sectional line of FIG. 8C. The plasma processing system 800 includes an assembly including the plasma chamber 100 and a heat sink 810 disposed within a transformer 822. The transformer 822, including a magnetic core 804 and one or more primary coils 824 (not shown), is adapted to couple (e.g., inductively couple) electrical power to a plasma generation volume defined by a plasma channel 802 of the plasma chamber 100. The magnetic core 804, together with the primary coil, can induce aligned electric fields and currents in the plasma channel 802, which can ignite and sustain a plasma in the plasma channel 802, forming a secondary circuit of the transformer 822.

[0047] Specifically, during operation, gas can be supplied to the plasma channel 802 via the gas inlet 806 until a pressure of, for example, about 0.133 Pa to about 133 KPa (about 0.001 Torr to about 1000 Torr) is reached. The transformer 822 induces an electric field that ionizes the gas in the plasma channel 802 of the plasma chamber 100 to form a plasma that completes a secondary circuit of the transformer 822. At least a portion of the plasma or activated gas in the plasma channel 802 can be delivered from the system 800 via the outlet flange 808. In some embodiments, before inductive power is coupled to the plasma, the gas inside the plasma channel 802 is ignited by an electric field applied to the plasma channel 802 to create an initial electrical breakdown. Several ignition schemes are described in U.S. Pat. Nos. 6,150,628, 7,166,816 and 7,659,489, which are assigned to MKS Instruments, Inc. of Andover, Massachusetts, the disclosures of which are incorporated herein by reference in their entireties.

[0048] In some embodiments, the heat sink 810 substantially encapsulates / surrounds the plasma chamber 100 with a thermal interface 812 disposed between the heat sink 810 and the plasma chamber 100. The heat sink 810 configured to remove heat from the plasma chamber 100 can be formed from a conductive material such as copper. In some embodiments, a cooling fluid is supplied to the cooling jacket via a fluid inlet 828 and removed via a fluid outlet 830. The thermal interface 812 can be a thermally conductive pad or potting compound with compliant properties. The thermal interface 812 has one or more mechanical properties that allow it to accommodate pressures induced by thermal deformation of the plasma chamber 100 within the heat sink 810 when the dielectric chamber is subjected to a thermal load from the plasma. The thermal interface 812 can have various degrees of compliance, such as being easily deformable, which helps to accommodate thermally induced dimensional changes of the system 800. The thermal interface 812 can also have a sufficiently high thermal conductivity to effectively conduct heat from the dielectric plasma chamber 100 towards the heat sink 810. The thermal interface 812 can be made compressible by introducing a small amount of porosity (0.1-10% by volume) into the material. In some embodiments, the gap between the plasma chamber 100 and the heat sink 810 is filled with the thermal interface 812, and the gap is about 0.020 inches wide.

[0049] In some embodiments, the two heat sink sections 810a, 810b are electrically separated / isolated from each other by one or more dielectric breaks 814 disposed along the second side / outside 104 and / or the first side / inside 102 of the plasma channel 802. For example, the dielectric breaks 814 can be disposed along the first side / inside bonding flange 110 and / or the second side / outside bonding flange 112 of the plasma chamber 100. These dielectric breaks 814 also provide spacing for the thermal interface 812. For example, the dielectric breaks 814 can be configured to include a thermal interface material in the gap between the plasma chamber 100 and the heat sink 810 and to prevent the thermal interface material from leaking out of the space between the heat sink 810 and the plasma chamber 100.

[0050] In some embodiments, the two heat sink sections 810a, 810b are further electrically separated along the toroidal direction of the plasma chamber 100. Such division of the heat sink 810 in the toroidal direction prevents currents from being induced in the heat sink 810 that could short out a secondary transformer formed by the plasma in the plasma channel 802.

[0051] FIG. 10 shows another cross-sectional view of the plasma processing system 800 along the B-B section line shown in FIG. 8C. As shown, the plasma chamber 100 is surrounded by azimuthally segmented heat sinks 810a, 810b and a magnetic core (e.g., magnetic core 804). The B-B section line crosses the junction of the toroidally segmented heat sink 810, and cooling fluid is guided between the segmented heat sink portions via a dielectric fluid coupling 826. In some embodiments, the dielectric fluid coupling 826 is made of a high temperature plastic. Similar heat sink segmentation configurations are described in U.S. Pat. Nos. 7,501,600 and 7,659,489, assigned to MKS Instruments, Inc. of Andover, Massachusetts, the disclosures of which are incorporated herein by reference in their entireties.

[0052] In addition to enabling a strong bond between the two portions 204, 206 of the plasma chamber 100 (see FIG. 2), the first and second bonding flanges 110, 112 provide the advantage of reducing temperature and thermal stress. Specifically, the first and second bonding flanges 110, 112 extend beyond the first and second sides 102, 104, respectively, of the plasma channel 802, thereby increasing the amount of contact surface area between the body of the plasma chamber 100 and the heat sink 810, as shown in FIGS. 9 and 11. This additional contact surface can result in a reduction in the peak temperature of the dielectric plasma chamber 100.

[0053] FIG. 12a shows a simulated temperature profile of the plasma chamber 100 of FIG. 1 with the first and second mating flanges 110, 112 according to an embodiment of the present invention. FIG. 12b shows a simulated temperature profile of the plasma chamber 1200 without the mating flanges. The first and second mating flanges 110, 112 used in the simulation of FIG. 12a both have a width of 0.635 cm (0.25 inches). The simulation uses an inlet cooling water temperature of 30° C. and an operating power load of 6 kilowatts (kW). As shown, the peak temperature is about 185° C. in the plasma chamber 1200 without the mating flanges, while the peak temperature with the mating flanges 110, 112 according to an exemplary embodiment of the present invention is about 153° C. This indicates that the use of the mating flanges 110, 112 can reduce the peak temperature rise of the plasma chamber 100 by about 20%.

[0054] Additionally, the first and second joining flanges 110, 112 can act as reinforcing ribs around the first side / inner side 102 and the second side / outer side 104 of the plasma chamber 100 to reduce deformation and thermal stresses of the plasma chamber 100 under thermal loads.

[0055] In another embodiment, the electrical separation / isolation of the two heat sink sections 810a, 810b provided by the dielectric break 814 and the joining flanges 110, 112 of the plasma chamber 100 allows them to be biased with opposite voltages for plasma ignition. FIG. 11 shows a cross-sectional view of an assembly including the plasma chamber 100 encapsulated by the heat sink sections 810a, 810b shown in FIGS. 8A, 8B, 10 and 11. The heat sink sections 810a, 810b are capacitively coupled to the plasma chamber 100 and can function as ignition electrodes to which a voltage can be applied for ignition of the gas 1104 in the plasma chamber 100. As shown, the two heat sink sections 810a, 810b can be biased with opposite polarities when connected to a power source 1102, which can be a DC, RF or pulsed power source, and the applied voltage can be from about several hundred volts to several kilovolts. As an example, the ignition electrodes in the form of heat sink sections 810a, 810b can be biased using a 400 kHz RF power supply with a peak-to-peak voltage of about 2-5 kV. When the voltage is applied, an electrical breakdown (e.g., electrical breakdown 1106) occurs inside the gas 1104 contained in the plasma channel of the plasma chamber 100. Since the ignition electrodes in the form of heat sink sections 810a, 810b cover substantially the entire second side / outside 104 of the plasma channel, the electrical breakdown 1106 is adapted to cover a large volume of the process gas 1104. This feature, in combination with the use of a toroidally oriented induced electric field in the plasma chamber 100, allows a toroidal plasma to be formed in the plasma chamber 100.

[0056] FIG. 13 illustrates an exemplary process 1300 for manufacturing the plasma chamber 100 of FIG. 1 according to some embodiments of the present invention. The plasma chamber 100 defines an internal plasma channel having a first side 102 (i.e., inner if the plasma channel is toroidal) and a second side 104 (i.e., outer if the plasma channel is toroidal). In step 1302, a first portion 204 of the plasma chamber 100 is constructed from a dielectric material, for example, by machining the dielectric material in the green state. In step 1304, a first portion 206 of the plasma chamber 100 is constructed from the same or a different dielectric material, for example, by machining the dielectric material in the green state. The first or second portion 204, 206 can be the top or bottom half of the plasma chamber 100. The first portion 204 has (i) a first flange 210 disposed along the first side 102 of the plasma channel and extending beyond the first side 102 by a first width, and (ii) a second flange 212 disposed along the second side 104 of the plasma channel and extending beyond the second side 104 by a second width. Similarly, the second portion 206 has (i) a third flange 216 disposed along the first side 102 of the plasma channel and extending beyond the first side 102 by a first width, and (ii) a fourth flange 218 disposed along the second side 104 of the plasma channel and extending beyond the second side 104 by a second width.

[0057] In some embodiments, after step 1304 but before the first and second portions 204, 206 are joined in step 1306, a coating is applied to the inner surface of the first and / or second wall portion 208, 214 in at least one of the first portion 204 or second portion 206 in step 1308, where the inner surface of the first and / or second wall portion 208, 214 forms at least a portion of a plasma channel exposed to the plasma therein. In some embodiments, the coating is a layer of an alloying agent deposited on the inner surface of the first wall portion 208 and / or second wall portion 214 of at least one of the first portion 204 or second portion 206.

[0058] In step 1306, the first and second portions 204, 206 are bonded to form the plasma chamber 100. Bonding the first and second portions 204, 206 includes (i) forming a bond between the first and third flanges 210, 216 of the first and second portions 204, 206, respectively, to create the first bonded flange 110, and (ii) forming a bond between the second and fourth flanges 212, 218 of the first and second portions 204, 206, respectively, to create the second bonded flange 112. If a layer of alloying agent is disposed on the inner surface of the first wall portion 208 and / or the second wall portion 210 during this bonding process, an alloy coating on the inner surface can be created from the layer of alloying agent by the same bonding process. Although the manufacturing process 1300 is described with respect to a toroidal plasma chamber having a toroidal plasma channel, the same process 1300 is also applicable to plasma chambers of other geometries, such as a plasma chamber having a plasma channel that is linear.

[0059] In some embodiments, the first and second portions 204, 206 can be bonded using high temperature low vapor pressure epoxy or glass frit bonding. In such embodiments, the first and second portions 204, 206 are fired / sintered prior to bonding. The epoxy or glass frit can be applied to at least the first and second flanges 210, 212 of the first portion 204. Bonding of the first and third flanges 210, 216 and the second and fourth flanges 212, 218 is accomplished by cooperatively heating the first and second portions to cure the epoxy or melt the glass frit to form the bonded interface 207. The curing temperature of epoxy is typically about 200-400°C, while the melting temperature of glass is about 1000-1500°C, both of which are significantly lower than the sintering temperature of high temperature ceramic materials. For example, the sintering temperature of alumina (Al2O3) ceramic is around 2000°C. Due to the difference between the epoxy cure / glass melting temperatures and the ceramic sintering temperatures in such embodiments, the sintering and bonding steps must be separated.

[0060] 14a-14c show another exemplary assembly for forming a plasma chamber according to some embodiments of the present invention. The plasma chamber 1400 is composed of two separate parts including a first part 1404 and a second part 1406 as shown in FIG. 14b and 14c. Each of the first part 1404 and the second part 1406 can include half of the plasma chamber 1400, with one part including a gas inlet and the other part including a gas outlet of the plasma chamber 1400. The two parts can be bonded together with flanges 1410, 1412 using a bonding agent. In some embodiments, the part 1404 and the part 1406 are geometrically identical. In some embodiments, the part 1404 and the part 1406 have different shapes to adapt or create a gas flow pattern along the plasma chamber 1400. The part 1404, the part 1406, and the bonding interface 1407 can be constructed from the same dielectric material or from two or more different dielectric materials. In some embodiments, the coating is disposed on an inner surface of the plasma chamber, the inner surface of the plasma chamber forming at least a portion of a plasma channel exposed to the plasma in the plasma chamber. The coating can include any of Al2O3, Y2O3, Sc2O3, La2O3, Ce2O3, MgO, SiO2, B4C, or an alloy including YAG. To optimize plasma performance, the inner surfaces of the inlet and outlet sections can be coated with different materials.

[0061] In another aspect, the plasma chamber and plasma processing system of the present invention can be used in various applications, such as semiconductor wafer processes that require halogen plasma. One exemplary semiconductor wafer process, called atomic layer etching (ALE), requires the use of a Cl* plasma and pulsed operation of the plasma source. The dielectric plasma chamber of the present invention (e.g., plasma chamber 100) is compatible with both of these requirements, since the erosion rate in the Cl* plasma is low and it can be used in a pulsed mode due to the ability to rapidly ignite the in-process gases.

[0062] In some embodiments, plasma processing systems of the present invention, such as plasma processing system 800, have low ion bombardment energy in a high density plasma environment and are therefore advantageous over other capacitively or inductively coupled sources that are subject to erosion of plasma-facing surfaces due to ion bombardment from the plasma. Thus, plasma processing systems of the present invention have low particle generation and long lifetimes (e.g., as measured by RF hours) under high plasma power densities. Fewer particle defects enable higher yields in the manufacture of semiconductor devices that are typically susceptible to submicroscopic particles that can cause defects in semiconductor devices.

[0063] Conventional plasma processing systems are typically made of metal (such as aluminum) with a dielectric coating on the inner surface to provide sufficient heat conduction to maintain the temperature of the plasma chamber within reasonable limits under high power plasma operating conditions. The choice of this material is due to the superior (e.g., more than 10 times) thermal conductivity of aluminum compared to common dielectric materials. For a given heat flux (QW / m 2 ), the temperature difference across the solid is calculated as ΔT=Q*Thx / k, where k is the thermal conductivity of the solid and Thx is the thickness of the solid through which heat is conducted. Thus, to minimize the temperature difference across the solid, k / Thx must be maximized. This means that the choice of material must be either a metal with high thermal conductivity or a thin dielectric material with low thermal conductivity. The advantage of using a purely dielectric plasma chamber is that it can handle the large voltages (e.g., up to tens of kV) required to quickly ignite the plasma in-process gas, whereas metallic plasma chambers are limited in such capabilities and usually require good ignition conditions (e.g., argon gas as the ignition gas) plus a transition to the process chemistry to sustain the plasma.

[0064] This advantage in the ignition capability of the dielectric plasma chamber allows the dielectric plasma chamber to be filled with electronegative gases (e.g., O2, NF3, F2, Cl2, etc.) during ignition without the additional transitions associated with switching from the noble / electropositive gas to the process gas. Such capability also allows the plasma to be pulsed (i.e., switched between on and off states), which is important for atomic layer processing applications such as ALE and ALD. Thus, the dielectric plasma chamber becomes the architecture of choice for use in remote plasma sources for pulsed radical delivery applications compared to alternatives such as remote inductively coupled plasma sources or microwave or dielectric barrier discharge based plasma sources.

[0065] Additionally, transformer-coupled plasma processing systems of the present invention, such as plasma processing system 800, can be operated to deliver certain chemical reactants for short periods of time. Figures 15a-15d show various exemplary pulsing operations using plasma processing system 800 of Figures 8A-8C as a remote plasma source, according to some embodiments of the present invention. Specifically, Figure 15a shows an exemplary pulsing operation when the remote plasma source 800 is operated (i.e., turned on) only when precursor B is flowed into the plasma chamber 100, either through the remote plasma source 800 or an inlet downstream of the remote plasma source 800, or directly into the plasma chamber 100. Other modes of operating the plasma processing system 800 as a remote plasma source are possible, such as turning on the remote plasma source only for precursor A, as shown in Figure 15b, or for both precursor A and precursor B, as shown in Figure 15c.

[0066] The same principle can be used when there is a single precursor with a constant flow rate and only the remote plasma source is switched to allow radical-based processing for specific periods within the entire process. In that case, the precursor-based process is used to adjust the rate and type of reaction downstream of the remote plasma source. One such example is the ALE process shown in Figure 15d. In this process, the precursor flowing through the remote plasma source can contain Cl2 or other halogen gases, which are converted to radicals including atomic chlorine and excited chlorine molecules for high reactivity at periodic intervals using an independent bias on the substrate to activate the surface and ion bombarding the substrate at intermittent times. In general, there are many ways to optimize these combinations to achieve a specific application. One common feature is having a low particle generation remote plasma source that can provide the radical flux required for chemical reactions at the atomic level. The remote plasma source can be rapidly switched on and off based on the process need to allow ignition within the process gas. Such a capability can be achieved by the plasma chamber and plasma processing system of the present invention. For example, the plasma chamber of the present invention can be formed from a dielectric material and coupled with a clamshell geometry that allows new coating materials to be integrated onto the plasma-facing surface that are compatible with the desired process chemistry.

[0067] In the context of the present invention, the term "about" is defined to be within ±50% of the value following the term "about." Although the present invention has been particularly shown and described with reference to certain 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 processing system comprising:

1. A plasma assembly comprising: a plasma chamber defining a plasma channel, the plasma chamber having an inner side and an outer side located on opposite sides along a length of the plasma channel, the plasma chamber having (i) two dielectric portions constructed from a dielectric material, and (ii) a bonding interface bonding the two dielectric portions along a bonding surface to form a hermetic seal between the two dielectric portions, the bonding interface including a first bonding flange extending inwardly from the inner side along the bonding surface and a second bonding flange extending outwardly from the outer side along the bonding surface; a plasma assembly comprising: a heat sink substantially surrounding the plasma chamber, the heat sink being divided along the mating surface into two conductive portions, the two conductive portions being constructed from a conductive material and being electrically isolated from one another; a power transformer including a magnetic core, a primary coil and the plasma assembly, the power transformer being configured to induce an electric field that ionizes gas in a plasma channel of the plasma chamber.

2. 10. The plasma processing system of claim 1, wherein the plasma assembly further comprises a thermal interface disposed between the heat sink and the plasma chamber, the thermal interface configured to provide at least one of accommodating thermally induced deformations of the plasma chamber or conducting heat from the plasma chamber towards the heat sink.

3. The plasma processing system of claim 2 , wherein the thermal interface is constructed from a compliant, thermally conductive material.

4. the second coupling flange is configured to extend outwardly from an exterior of the plasma chamber generally parallel to the coupling surface; 2. The plasma processing system of claim 1, wherein the first coupling flange is configured to extend inwardly from inside the plasma chamber generally parallel to the coupling surface.

5. 5. The plasma processing system of claim 4, wherein the plasma assembly further comprises one or more dielectric breaks disposed along at least one of the second mating flange or the first mating flange of the plasma chamber at the mating interface.

6. 6. The plasma processing system of claim 5, wherein the two conductive portions of the heat sink are electrically separated by the one or more dielectric breaks and at least one of the second bonding flange and the first bonding flange at the bonding interface.

7. 10. The plasma processing system of claim 1 , wherein the plasma assembly further comprises one or more dielectric fluid couplings disposed within the plasma assembly, the dielectric fluid couplings in fluid communication with the conductive portions of the heat sink to conduct a cooling fluid between the conductive portions.

8. 10. The plasma processing system of claim 1, further comprising a support structure configured to support and cool a magnetic core of the power transformer.

9. The plasma processing system of claim 1 , wherein the bonding interface includes a bonding material that is one of a glass frit, a eutectic, or an epoxy.

10. 2. The plasma processing system of claim 1, wherein a first dielectric portion of the dielectric portion of the plasma chamber and a first conductive portion of the conductive portion of the heat sink are disposed in a first half of the power transformer relative to the coupling surface, and a second dielectric portion of the dielectric portion of the plasma chamber and a second conductive portion of the conductive portion of the heat sink are disposed in a second half of the power transformer relative to the coupling surface.

11. 11. The plasma processing system of claim 10, wherein the first and second dielectric portions of the plasma chamber have the same geometric shape, and the first and second conductive portions of the heat sink have the same geometric shape.

12. 1. A method of operating a plasma processing system, comprising: providing a plasma processing system including a power transformer having at least one magnetic core, a primary coil, and a plasma assembly, the plasma assembly including: (i) a plasma chamber defining a plasma channel, the plasma chamber having an inner side and an outer side located on opposite sides along a length of the plasma channel, the plasma chamber being generated by two dielectric portions coupled to each other to form a coupling interface along a coupling surface, the coupling interface including a first coupling flange extending inwardly from the inner side along the coupling surface and a second coupling flange extending outwardly from the outer side along the coupling surface; and (ii) a heat sink substantially surrounding the plasma chamber, the heat sink being divided into two conductive portions along the coupling surface, the two conductive portions being electrically isolated from each other; supplying a gas to the plasma channel via a gas inlet; inducing an electric field with the power transformer that ionizes gas in a plasma channel of the plasma chamber to form a plasma; and expelling at least a portion of the plasma from the plasma channel through an exit flange.

13. 13. The method of claim 12, further comprising biasing two conductive portions of the heat sink with opposite voltages to ignite a gas in the plasma channel prior to inducing an electric field in the plasma channel.

14. 13. The method of claim 12, further comprising electrically isolating the two conductive portions at the coupling interface with one or more dielectric breaks and at least one of a first coupling flange and a second coupling flange of the plasma chamber.

15. 15. The method of claim 14, wherein (i) the second coupling flange extends outwardly from outside the plasma chamber generally parallel to the coupling surface, and (ii) the first coupling flange extends inwardly from inside the plasma chamber generally parallel to the coupling surface.

16. 16. The method of claim 15, further comprising increasing an amount of contact surface between the plasma chamber and the heat sink by a first mating flange and a second mating flange of the plasma chamber, thereby reducing a peak temperature within the plasma chamber.

17. 16. The method of claim 15, further comprising the step of reinforcing a plasma chamber in the power transformer with a first and a second coupling flange of the plasma chamber, thereby reducing deformation and thermal stress of the plasma chamber.

18. The method of claim 12 , further comprising cooling the heat sink by conducting a cooling fluid through a plurality of dielectric fluid couplings in fluid communication with two conductive portions of the heat sink.

19. The method of claim 12 , further comprising reducing thermally induced deformation of the plasma chamber with a thermal interface located between the plasma chamber and the heat sink.

20. The method of claim 19 , wherein the thermal interface is further configured to conduct heat from the plasma chamber towards the heat sink.

21. The method of claim 12 , further comprising operating the plasma processing system as a remote plasma source in a pulsed operation.

Images