Inductively coupled plasma source with radial coil network

Abstract

An apparatus for inductively generating plasma in a process chamber utilizes a radial coil network. In some embodiments, the radial coil network is a planar structure including an inner conductor having an open center, wherein at least one RF power source is electrically connected to the inner conductor at a power node; an outer conductor spaced apart from and surrounding the inner conductor, wherein at least one ground is electrically connected to the outer conductor at a ground node; a plurality of branch conductors extending from the inner conductor to the outer conductor, wherein the plurality of branch conductors are evenly distributed in the radial coil network; and a plurality of capacitors, wherein at least one capacitor of the plurality of capacitors is electrically inserted into each branch conductor of the plurality of branch conductors.

Description

Technical Field

[0001] The implementation of the principles of this invention generally relates to the semiconductor processing of semiconductor substrates. Background Technology

[0002] Plasma is frequently used in semiconductor processing for etching and deposition. In some cases, inductive plasma power supplies can be used to generate plasma within the process volume of an etching process chamber. However, the inventors have observed that inductive plasma power supplies often result in variations in plasma density, which lead to non-uniformity and other anomalies that reduce process yield within the process chamber.

[0003] Therefore, the inventors have provided an improved inductively coupled plasma source with a radial coil network, which substantially improves uniformity and enhances plasma density by precisely controlling plasma density and generating strong resonant current within the coil network. Summary of the Invention

[0004] This article provides an apparatus for improving plasma density control in process chambers using an inductively coupled plasma source.

[0005] In some embodiments, an apparatus for inductively generating plasma in a process chamber may include a radial coil network having a planar structure, the radial coil network including an inner conductor having an open center, wherein at least one RF power supply is electrically connected to the inner conductor at a power node; an outer conductor spaced apart from and surrounding the inner conductor, wherein at least one grounding element is electrically connected to the outer conductor at a grounding node; a plurality of branch conductors extending from the inner conductor to the outer conductor, wherein the plurality of branch conductors are uniformly distributed in the radial coil network; and a plurality of capacitors, wherein at least one of the plurality of capacitors is electrically inserted into each of the plurality of branch conductors.

[0006] In some embodiments, the device may further include: an inductive power excitation source positioned directly above a radial coil network, the inductive power excitation source having a circular open-loop structure or a helical structure; at least one of the plurality of capacitors being a vacuum capacitor; at least one of the plurality of capacitors being a variable capacitor; and each of the plurality of capacitors having a capacitance of approximately 100 pF to approximately 800 pF. The capacitance value is pF; a phase shifter is inserted between at least one RF power supply and a radial coil network, wherein the phase shifter has a first output with zero phase, a second output with a phase of 120 degrees, and a third output with a phase of 240 degrees, wherein the first output is electrically connected to a first power node, which is an interconnection point between a first branch conductor and an inner conductor, the second output is electrically connected to a second power node, which is an interconnection point between a second branch conductor and an inner conductor, and the third output is electrically connected to a third power node, which is an interconnection point between a third branch conductor and an inner conductor, wherein the first power node, the second power node, and the third power node are angularly separated by 120 degrees, the inner conductor has a hexagonal or octagonal shape, a plurality of branch conductors have non-tangential connections at the inner conductor and non-tangential connections at the outer conductor, the first power node is located at the first end of the first branch conductor of the plurality of branch conductors at the inner conductor, and the first ground node is located at the first branch of the plurality of branch conductors. The conductor is located at the second end of the outer conductor, the second power node is located at the first end of the second branch conductor of the plurality of branch conductors at the inner conductor, and the second ground node is located at the second end of the second branch conductor of the plurality of branch conductors at the outer conductor, wherein the first branch conductor and the second branch conductor are spaced 180 degrees apart in the radial coil network, at least one RF power supply having a first frequency is connected to the first power node, and at least one RF power supply having a second frequency is connected to the second power node, the first frequency being different from the second frequency; a variable phase shift assembly is inserted between at least one of the at least one RF power supply and the plurality of power nodes, the plurality of power nodes being located at each electrical connection of the plurality of branch conductors and the inner conductor, the radial coil network being surrounded by a coupled static magnetic field coil electrically connected to a DC bias power supply, at least one shunt variable capacitor being electrically connected between the inner conductor and the grounding element, and / or the plurality of branch conductors having eight or more branch conductors.

[0007] In some embodiments, an apparatus for inductively generating plasma in a process chamber may include a radial coil network having a planar structure, the radial coil network comprising: an inner conductor having an open center, wherein a first RF power supply is electrically connected to the inner conductor at a first power node, and a second RF power supply is electrically connected to the inner conductor at a second power node; an outer conductor spaced apart from and surrounding the inner conductor, wherein a first grounding element is electrically connected to the outer conductor at a first grounding node opposite to the first power node, and a second grounding element is electrically connected to the outer conductor at a second grounding node opposite to the second power node; a plurality of branch conductors extending from the inner conductor to the outer conductor, wherein the plurality of branch conductors are uniformly distributed around the inner conductor in the radial coil network, and wherein a first branch conductor of the plurality of branch conductors is electrically inserted between the first power node and the first grounding node, and a second branch conductor of the plurality of branch conductors is electrically inserted between the second power node and the second grounding node; and a plurality of capacitors, wherein at least one of the plurality of capacitors is electrically inserted into each of the plurality of branch conductors, and wherein at least one of the at least one capacitor is a variable capacitor.

[0008] In some embodiments, the device may further include a first RF power supply and a second RF power supply, which are different in frequency, phase or amplitude.

[0009] In some embodiments, an inductively coupled plasma (ICP) process chamber for processing a substrate by plasma may include: a chamber body having a cover, a process volume, and a substrate support; a first RF power supply having a first frequency; a second RF power supply having a second frequency; and a radial coil network having a planar structure positioned above the cover of the process chamber, the radial coil network including an inner conductor having an open center, wherein the first RF power supply is electrically connected to the inner conductor at a first power node, and the second RF power supply is electrically connected to the inner conductor at a second power node; and an outer conductor spaced apart from and surrounding the inner conductor, wherein a first grounding element is located opposite the first power node. The grounding node is electrically connected to the outer conductor, and the second grounding element is electrically connected to the outer conductor at the second grounding node opposite to the second power node; a plurality of branch conductors extending from the inner conductor to the outer conductor, wherein the plurality of branch conductors are uniformly distributed around the inner conductor in a radial coil network, and wherein a first branch conductor of the plurality of branch conductors is electrically inserted between the first power node and the first grounding node, and a second branch conductor of the plurality of branch conductors is electrically inserted between the second power node and the second grounding node; and a plurality of capacitors, wherein at least one of the plurality of capacitors is electrically inserted into each of the plurality of branch conductors, and wherein at least one of the at least one capacitor is a variable capacitor.

[0010] Other implementation methods are disclosed below. Attached Figure Description

[0011] The embodiments of the principles of the invention, which have been briefly summarized above and will be discussed in more detail below, can be understood by referring to the illustrative embodiments of these principles depicted in the accompanying drawings. However, the drawings only show typical embodiments of these principles and should therefore not be considered as limiting the scope, as other equally effective embodiments are permissible.

[0012] Figure 1 A cross-sectional view of an inductively coupled plasma (ICP) process chamber according to some embodiments of the principles of the present invention is depicted.

[0013] Figure 2 A top view and a cross-sectional view of a radial coil network according to some embodiments of the principles of the present invention are depicted.

[0014] Figure 3 A top view depicting a radial coil network with dual RF power supplies according to some embodiments of the principles of the present invention is shown.

[0015] Figure 4 Top and cross-sectional views of a multiphase RF power supply for a radial coil network, according to some embodiments of the principles of the present invention, are depicted.

[0016] Figure 5 Top and cross-sectional views of a three-phase RF power supply for a radial coil network, according to some embodiments of the principles of the present invention, are depicted.

[0017] Figure 6 An isometric view of a radial coil network excited by an inductive power excitation source, illustrating some embodiments of the principles of the present invention.

[0018] Figure 7 A top view and a cross-sectional view of a radial coil network incorporating a static magnetic field coil, illustrating some embodiments of the present invention, based on the principles of the present invention.

[0019] Figure 8 A top view depicting a radial coil network with a variable capacitor according to some embodiments of the principles of the present invention is shown.

[0020] Figure 9 A top view depicting a radial coil network with a different number of radial branch conductors according to some embodiments of the principles of the present invention is shown.

[0021] Figure 10 A top view depicting a radial coil network with obliquely positioned radially branched conductors according to some embodiments of the principles of the present invention is shown.

[0022] Figure 11 A top view depicting various inner conductor, outer conductor, and radial branch conductor shapes according to some embodiments of the principles of the present invention is provided.

[0023] Figure 12 An isometric view and cross-sectional view of a radial coil network placed in a single plane, according to some embodiments of the principles of the present invention, are depicted.

[0024] For ease of understanding, the same reference numerals have been used to denote common elements in the figures where possible. The figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be advantageously incorporated into other embodiments without further description. Detailed Implementation

[0025] Radio frequency (RF) inductively coupled plasma (ICP) sources use radial coil networks to create a uniform plasma density within a process chamber. The radial coil network facilitates the induction of multiple resonances, generating strong currents and electromagnetic fields when resonance is achieved within the process chamber. The radial coil network also allows for a larger antenna cross-sectional area, enabling better power delivery into the process chamber. Vacuum capacitors can be used in each branch of the radial coil network to allow for additional tuning of the resonant frequencies generated within the process volume. The radial coil network also offers the advantage of handling and controlling higher current levels to enhance plasma density. Precise skew control of current distribution and plasma uniformity through capacitance and phase tuning further enhances the flexibility of the radial coil network. The current flowing through different branches of the radial coil network can be independently adjusted to achieve flexible skew control. Furthermore, the radial coil network can be inductively excited using various RF power excitation and coupling structures. The use of radial branch conductors in the radial coil network allows for precise determination of the current within each branch, accurately controlling edge profiles and enhancing overall uniformity.

[0026] Reactive ion etching (RIE) is the most widely used plasma etching technique. RIE utilizes directed ion bombardment to enhance the surface etching reaction rate and achieve contour control. The RF ICP source is positioned at the top of the reaction chamber. The ICP source generates a large number of reactive species and controls the plasma density and ion flux. The operating principle of the RF ICP source is to induce an RF current in the reaction chamber by flowing current into adjacent coils. The coil structure becomes an integral part of the ICP source. However, conventional ICP sources use helical-based coils, which have limited performance and cannot support future semiconductor processing technologies. Therefore, future research and development in advanced semiconductor manufacturing will require higher-performance RIE equipment, which cannot be achieved with conventional ICP sources with helical-based coil structures.

[0027] The radial coil network based on the principles of this invention provides a planar coil structure that offers higher performance and control over plasma in process chambers to meet the upcoming advancements in the semiconductor manufacturing industry. Figure 1This is an example of an ICP process chamber 100. Embodiments of the principles of this invention can be used with any type of ICP process chamber, such as, but not limited to, RIE reactor chambers and the like. The ICP process chamber 100 has a chamber body 102 having a cover 104, a process volume 108, a substrate support 106, and an ICP source 140. The ICP process chamber 100 may also have a gas supply 142 for supplying process gases to the process volume 108. In some embodiments, the ICP process chamber 100 may also have a feed-through device 144, which may be, but is not limited to, a feed-through gas supply and / or a feed-through remote plasma source (RPS) and the like.

[0028] The substrate support 106 provides a platform for holding the substrate 126 within the process volume 108 during processing. The plasma 110 is inductively formed using an ICP source 140, which includes a radial coil network 112 and an RF power supply. The radial coil network 112 of this invention is a planar coil structure positioned directly above the cover 104 of the ICP process chamber 100. In some embodiments, the radial coil network 112 is connected to a first RF power supply 122 via a first mating network 118 and grounded via a first grounding member 114. In some embodiments, a second RF power supply 124 may be optional and can be connected to the radial coil network 112 via a second mating network 120 and grounded via a second grounding member 116. Any number of RF power supplies and grounding members may be implemented together with the radial coil network 112.

[0029] Controller 138 controls the operation of any aspect of the ICP process chamber as described herein. Controller 138 may use direct control of the ICP process chamber 100, or alternatively, by controlling a computer (or controller) associated with the ICP process chamber 100. In operation, controller 138 implements data collection and feedback from the ICP process chamber 100 and / or the ICP source 140 to optimize the performance of the ICP process chamber 100 and / or the ICP source. Controller 138 generally includes a central processing unit (CPU) 132, memory 134, and support circuitry 136. CPU 132 may be any type of general-purpose computer processor suitable for industrial settings. Support circuitry 136 is conventionally coupled to CPU 132 and may include cache, frequency circuitry, input / output subsystems, power supplies, and the like. Common software programs (such as methods and aspects of operating the device, including the radial coil network 112 as described herein) may be stored in memory 134, and when executed by CPU 1322, CPU 132 is transformed into a dedicated computer (controller 138). Common software programs may also be stored in and / or executed by a second controller (not shown), which is located remotely from the ICP process chamber 100.

[0030] Memory 134 is in the form of a computer-readable storage medium containing instructions that, when executed by CPU 132, facilitate the operation of semiconductor processes and the ICP source 140, including the radial coil network 112. The instructions in memory 134 are in the form of a program product, such as a program that implements operational aspects of the principles of the present invention (e.g., phase shift / skew control of the radial coil network 112 and the like). The program code may conform to any of a number of different programming languages. In one instance, this disclosure may be implemented as a program product stored on a computer-readable storage medium for use with a computer system. Several program-defined aspects of the program product (including the operational processes and controls described herein) define functionality. Illustrative computer-readable storage media include, but are not limited to: non-writable storage media (e.g., read-only memory elements within a computer, such as CD-ROM disks readable by a CD-ROM drive, flash memory, ROM chips, or any type of solid-state non-volatile semiconductor memory elements) on which information is permanently stored; and writable storage media (e.g., floppy disks or hard disk drives within a disk drive, or any type of solid-state random access semiconductor memory) on which changeable information is stored. When a computer-readable storage medium carries computer-readable instructions that direct the functionality of the methods described herein, such a medium is an aspect of the principles of the invention.

[0031] The radial coil network 112 of the present invention has an inner conductor 202 having a ring shape, which allows for easy installation, such as, but not limited to, remote plasma sources (RPS) and / or center-fed gas sources and the like, in process chambers having center-fed devices 144. Figure 2 As depicted in view 200A. The inner conductor 202 may be circular or have a pentagonal, hexagonal, or octagonal shape and similar (see, for example, see...). Figure 11 Other shapes are possible, as long as the inner conductor shape maintains symmetry with respect to the radial branch conductors 204. For brevity, the example radial coil network described herein can be depicted by, but is not limited to, six linear radial branch conductors. More or fewer radial branch conductors 204 can be used, as long as symmetry is maintained within the radial coil network 112 (see, for example, [reference needed]). Figure 9 Radial branch conductor 204 begins at inner conductor 202 and terminates at outer conductor 206. Radial coil network 112 has a planar coil structure. As used herein, a planar coil structure is a coil structure in which inner conductor 202, outer conductor 206, and radial branch conductor 204, as a whole, can intersect with a single plane 1202, such as... Figure 12 As depicted in views 1200A and 1200B.

[0032] Using capacitors 208 electrically inserted into radial branch conductors 204, capacitance is added to each of the radial branch conductors 204, such as Figure 2 View 200B and Figure 2 The enlarged view 210 depicts the connection details of the capacitor electrical connection in each of the radial branch conductors 204. In subsequent views, the connection details may be simplified to fewer connection details, but are still electrical connections, as indicated in the enlarged view 210. In some embodiments, capacitor 208 may be a vacuum capacitor or the like. In some embodiments, capacitor 208 may be a variable capacitor to allow tuning of the radial coil network 112. In some embodiments, capacitor 208 may have a capacitance value of approximately 100 picofarads (pF) to approximately 800 picofarads (pF). The capacitance value depends on the capacitance required to produce the fundamental resonant frequency given the inductance of each of the radial branch conductors 204 (the inductance value is affected by the length of each of the radial branch conductors 204). The inner conductor 202, outer conductor 206, and radial branch conductors 204 may be formed of copper. The cross-section of the copper material may be rectangular, circular, elliptical, and / or square, or the like.

[0033] Operablely, the radial coil network 112 is positioned above the cover 104 of the ICP process chamber 100 and generates inductive coupling between the radial coil network 112 and the working gas within the process volume 108 of the chamber body 102. In some embodiments, a first RF power supply 122 is connected to a first power node 212 via a first matching network 118 at the electrical intersection of the inner conductor 202 and the first radial branch conductor 214. A first ground node 114 is connected to the outer conductor 206 at a first ground node 216 at the electrical intersection of the first radial branch conductor 214 and the outer conductor 206. The positions of the power node and the ground node affect the current flowing through the radial coil network 112. By changing the connection points of the power supply and the ground node, the current flowing through the radial branch conductor 204 can be adjusted.

[0034] In some implementations, dual RF power supplies can be used, such as Figure 3 As depicted in view 300 above. Figure 1 The first RF power supply 122 is described as being connected. The second RF power supply 124 is connected to the second power node 316 via a second matching network 120 at the electrical intersection of the inner conductor 202 and the second radial branch conductor 320 (connected 180 degrees to the first RF power supply). The second ground node 116 is connected to the outer conductor 206 at the second ground node 318 at the electrical intersection of the second radial branch conductor 320 and the outer conductor 206 (connected 180 degrees to the first ground node). The positions of the power node and the ground node affect the current flowing through the radial coil network 112. By changing the attachment points of the power supply and the ground node, the current flowing through the radial branch conductor 204 can be adjusted accordingly. The first RF power supply 122 and the second RF power supply 124 may differ in frequency, phase, and / or amplitude. Example frequencies may include, but are not limited to, 13.56 MHz and / or 60 MHz and the like. In some embodiments, the output characteristics of the two power supplies are identical to produce a mirror effect of the current flowing through the radial coil network 112.

[0035] Compared to a single RF power supply solution, a dual RF power supply solution offers greater operational flexibility because the current distribution in different radial branch conductors can be tuned by the phase difference, amplitude difference, and / or even drive frequency difference between the two RF power supplies. The dual RF power supply solution provides more ways to achieve skew control to improve plasma uniformity. As used herein, skew control refers to influencing the density in different regions of the plasma by controlling the characteristics (e.g., resonance, amplitude, phase, frequency, etc.) of the current flowing through each of the radial branch conductors 204 of the radial coil network 112, ultimately affecting, for example, the etching uniformity on the substrate surface and the like.

[0036] exist Figure 4In view 400, in some embodiments, a phase shifter 406 is interposed between a first matching network 118 of the first RF power supply 122 and six power nodes corresponding to the intersection points 408 of the six radial branch conductors 204 and the inner conductor 202. In some embodiments, the phase shifter 406 includes an FPGA-powered coupler 402 that receives a phase setting command from an operator and generates a specific signal to drive all six phase shifters 404. Any combination of RF source conditions can be achieved through the phase shifter configuration. Although the two grounding elements (first grounding element 114, second grounding element 116) are in Figure 4 The grounding element is depicted as being connected to the outer conductor 206, but other grounding configurations may be used, such as, but not limited to, varying the number of grounding nodes and / or changing the grounding location and the like. By changing the number and / or location of the grounding elements, the current and voltage distribution in the radial coil network 112 can be further manipulated to achieve enhanced skew control.

[0037] exist Figure 5 In view 500, in some embodiments, a three-phase operation configuration uses a phase shifting assembly 540. In some embodiments, the phase shifting assembly 540 includes a power divider 502 and three phase shifters 504. A first phase shifter 506 outputs a signal with zero-degree phase, a second phase shifter 508 outputs a signal with 120-degree phase, and a third phase shifter 510 outputs a signal with 240-degree phase. RF power from the first RF power source 122 is distributed by the power divider 502 to the three phase shifters 504, with each phase shifter sharing the same amount of power. The three phase shifters 504 create output signals with a 120° phase difference between every two adjacent power supply branches. Three power nodes 514, 516, 518 are located at the ends of three radial branch conductors on the inner conductor 202, wherein each radial branch conductor of the three power nodes 514, 516, 518 is angularly separated by 120 degrees 530. The other end of each radial branch conductor connected to the three power nodes 514, 516, 518 is grounded 520, 522, 524. In a three-phase operating configuration, the maximum and minimum currents alternate in the radial branch conductors connected to the three power nodes 514, 516, 518, thereby generating a rotating electromagnetic field 550 below the radial coil network 112. Since the rotation frequency of the field is the same as that of the first RF power supply 122, a uniform plasma can be generated assuming that the on-time of the ICP RF power is much longer than the RF frequency cycle.

[0038] In addition to implementations using direct coupling between the RF power supply and the radial coil network 112, in some implementations, indirect coupling configurations may be used. Figure 6In view 600A, an inductive power excitation source 602 with a circular open-loop structure is used in conjunction with a first RF power supply 122 to power the radial coil network 112. The inductive power excitation source 602 is positioned directly above the radial coil network 112 to inductively couple 606 with the radial coil network 112 to excite power within the radial coil network 112. By properly positioning the inductive power excitation source 602, the current in each radial branch conductor 204 can be made substantially equal, and thus a quasi-uniform plasma can be generated. However, with the excitation configurations of views 600A and 600B, phase control in each of the radial branch conductors 204 can no longer be achieved. Figure 6 In view 600B, in some embodiments, an inductive power excitation source 604 with a helical structure is used in conjunction with a first RF power supply 122 to power the radial coil network 112. The number of turns and size of the helical structure can vary between operations and are not limited to this. Figure 6 As shown above, a portion of the electromagnetic field energy generated by the helical structure excites the underlying radial coil network 112, while the remainder penetrates the chamber wall 608 and contributes to plasma generation in the process volume 108. Therefore, extremely high plasma density can be achieved in the reaction chamber. The use of indirect coupling simplifies the driving of the radial coil network 112, as only a single RF power supply needs to ensure uniformity. Furthermore, the radial coil network can be excited by an inductive power excitation source, eliminating the need for any grounding nodes in the outer conductor 206, since current can now be directly induced within the internal loop of the radial coil network.

[0039] In some embodiments, the radial coil network 112 can operate in conjunction with the coupled static magnetic field generated by the magnetic field coil 704, such as Figure 7 The magnetic field coil 704 is depicted in top view 700A and cross-sectional view 700B. In top view 700A, a radial coil network 112 surrounds the top of the chamber body 102. The magnetic field coil 704 is electrically connected to a DC bias source 702 at connection point 708 and to a grounding element 706 to generate a static magnetic field. The introduction of the static magnetic field provides additional control over the density and angular distribution of ions / electrons in the process volume 108 of the ICP process chamber 100.

[0040] In the above embodiment, the current distribution in the radial coil network 112 can be tuned simply by changing the RF power supply and grounding conditions. To further improve system tunability, a variable capacitor 802 can be introduced into the radial coil network 112, such as... Figure 8 As illustrated. In some embodiments, any fixed capacitor 804 can be replaced with a variable capacitor 802. Figure 8Three configurations are depicted in views 800A, 800B, and 800C. In view 800A, variable capacitors 802 are orthogonally placed on two of the radial branch conductors 204, and the remaining radial branch conductors 204 have fixed capacitors 804. The configuration depicted in view 800A achieves equal current amplitudes in all radial branch conductors 204 by simultaneously tuning the two variable capacitors. That is, the capacitance value of the variable capacitors 802 is equalized and then tuned until equal current amplitudes are obtained in all radial branch conductors 204. A homogeneous plasma is then generated in the process chamber below.

[0041] In some embodiments, as depicted in view 800B, variable capacitors 802 are used in all radial branch conductors 204 of the radial coil network 112. This configuration further enhances skew control over plasma generation because the effects of asymmetric components (such as, but not limited to, interconnected radial branch conductors 204 of unequal sizes) can now be individually offset by capacitor tuning. In some embodiments, as depicted in view 800C, current tuning can be achieved via grounded shunt variable capacitors 808. In some embodiments, more or fewer shunt variable capacitor branches may be connected to any power node on the radial coil network 112, and the implementation is not limited to the configuration presented in view 800C.

[0042] In some embodiments, the number of radial branch conductors 204 can be as follows: Figure 9 The details vary from, but are not limited to, those depicted in views 900A and 900B. In view 900A, eight shunt or radial branch conductors 204 are depicted. In view 900B, ten shunt or radial branch conductors 204 are depicted. Increasing the number of radial branch conductors 204 strengthens the electromagnetic field below the radial coil network 112, thus increasing the generated plasma density. (The last sentence appears to be incomplete and possibly contains errors.) Figure 8 The fully variable capacitor configuration shown in view 800B can achieve more precise skew control of plasma homogeneity by increasing the number of radial branch conductors.

[0043] In some implementations, "skewed" radial branch conductors may be used, such as Figure 10 As depicted in view 1000. In this document, "slanted" is used to indicate that the outward travel of the radial branch conductor 204 is not perpendicular to the tangent of each contact point or node on the inner conductor 202 and the outer conductor 206. From a circuit viewpoint, there is no significant difference between slanted and straight branch coil networks. However, the increased branch conductor length of the slanted branch network provides a larger effective antenna cross-sectional area, thereby enabling indirect coupling of the RF power supply using the excitation source (e.g., see...). Figure 6(See Views 600A and 600B, etc.) for greater efficiency. Furthermore, the oblique branch network improves the mechanical stability of the radial coil network because the connection points are more robust. In addition to oblique branches, curved branches and other nonlinear branches can be used (see, for example, see...). Figure 11 This improves installation flexibility and / or allows for bypassing obstacles on the top of the process chamber.

[0044] For brevity, the embodiments described above have been discussed individually. However, any combination of aspects from each of these embodiments can be combined to form another embodiment of the radial coil network 112. For example, a variable capacitor and / or a shunt variable capacitor connected to a ground can be used in the embodiments described above. Similarly, a phase-shifting component can be used in other embodiments. Multiple RF power supplies having the same frequency and / or different frequencies and / or different phases and the like can also be utilized in various embodiments. Varying power amplitudes can also be used for a single RF power supply and / or in conjunction with multiple RF power supplies. Inner and / or outer conductors with varying shapes can be used in the embodiments described above, such as... Figure 11 As depicted. In Figure 11 In view 1100A, the inner conductor 202 and / or the outer conductor 206 may be pentagonal, hexagonal, and / or octagonal, or similar. Figure 11 In view 1100B, the radial branch conductor 204 has a non-linear "S" shape. Figure 11 In view 1100C, the radial branch conductor 204 has a curved shape. The nonlinear nature of the radial branch conductor 204 in views 1100B and 1100C allows for an increase in the length of the radial branch conductor, thereby increasing the effective antenna cross-sectional area. The nonlinear radial branch conductor also allows for easier installation when there are obstructions on the top of the process chamber.

[0045] Embodiments of the present invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments may also be implemented as instructions stored using one or more computer-readable media, which may be read and executed by one or more processors. The computer-readable media may include any mechanism for storing or transmitting information in a machine-readable form (e.g., a computing platform or a “virtual machine” running on one or more computing platforms). For example, the computer-readable media may include any suitable form of volatile or non-volatile memory. In some embodiments, the computer-readable media may include non-transitory computer-readable media.

[0046] Although the foregoing describes embodiments of the principles of the present invention, other embodiments of the principles of the present invention may be devised without departing from their basic scope.

Claims

1. An apparatus for inductively generating plasma in a process chamber, the apparatus comprising: A radial coil network having a planar structure, the radial coil network being configured to inductively generate plasma in the process chamber, comprising: An inner conductor having an open center, wherein at least one RF power source is electrically connected to the inner conductor at a power node; An outer conductor, which is spaced apart from and surrounds the inner conductor, wherein at least one grounding element is electrically connected to the outer conductor at a grounding node; Multiple branch conductors extending from the inner conductor to the outer conductor, wherein the multiple branch conductors are uniformly distributed in the radial coil network; as well as A plurality of capacitors, wherein at least one of the plurality of capacitors is electrically inserted into each of the plurality of branch conductors.

2. The device of claim 1, further comprising: An inductive power excitation source is positioned directly above the radial coil network.

3. The device as claimed in claim 2, wherein the inductive power excitation source has a circular open-loop structure or a spiral structure.

4. The device of claim 1, wherein at least one of the plurality of capacitors is a vacuum capacitor.

5. The device of claim 1, wherein at least one of the plurality of capacitors is a variable capacitor.

6. The device of claim 1, wherein each of the plurality of capacitors has a capacitance value of approximately 100 pF to approximately 800 pF.

7. The device of claim 1, further comprising: A phase shifter assembly is inserted between the at least one RF power supply and the radial coil network, wherein the phase shifter assembly has a first output with zero phase, a second output with a phase of 120 degrees, and a third output with a phase of 240 degrees. The first output is electrically connected to a first power node, which is an interconnection point between a first branch conductor and the inner conductor; the second output is electrically connected to a second power node, which is an interconnection point between a second branch conductor and the inner conductor; and the third output is electrically connected to a third power node, which is an interconnection point between a third branch conductor and the inner conductor. The first power node, the second power node, and the third power node are separated by a 120-degree angle.

8. The device of claim 1, wherein the inner conductor has a hexagonal or octagonal shape.

9. The device of claim 1, wherein the plurality of branch conductors have a non-tangential connection at the inner conductor and a non-tangential connection at the outer conductor.

10. The device of claim 1, wherein the first power node is located at a first end of the first branch conductor of the plurality of branch conductors at the inner conductor, and the first ground node is located at a second end of the first branch conductor of the plurality of branch conductors at the outer conductor.

11. The device of claim 10, wherein the second power node is located at a first end of the second branch conductor of the plurality of branch conductors at the inner conductor, and the second ground node is located at a second end of the second branch conductor of the plurality of branch conductors at the outer conductor, and wherein the first branch conductor and the second branch conductor are spaced 180 degrees apart in the radial coil network.

12. The device of claim 11, wherein a first RF power supply having a first frequency is connected to the first power node, and a second RF power supply having a second frequency is connected to the second power node.

13. The device of claim 12, wherein the first frequency is different from the second frequency.

14. The apparatus of claim 1, further comprising: A variable phase shift assembly is inserted between at least one of the at least one RF power source and a plurality of power nodes, the plurality of power nodes being located at each electrical connection between the plurality of branch conductors and the inner conductor.

15. The device of claim 1, wherein the radial coil network is surrounded by coupled static magnetic field coils electrically connected to a DC bias power supply.

16. The apparatus of claim 1, further comprising: At least one shunt variable capacitor is electrically connected between the inner conductor and the grounding element.

17. The device of claim 1, wherein the plurality of branch conductors has eight or more branch conductors.

18. An apparatus for inductively generating plasma in a process chamber, the apparatus comprising: A radial coil network having a planar structure, the radial coil network being configured to inductively generate plasma in the process chamber, comprising: An inner conductor having an open center, wherein a first RF power supply is electrically connected to the inner conductor at a first power node, and a second RF power supply is electrically connected to the inner conductor at a second power node; An outer conductor, spaced apart from and surrounding the inner conductor, wherein a first grounding element is electrically connected to the outer conductor at a first grounding node opposite to the first power node, and a second grounding element is electrically connected to the outer conductor at a second grounding node opposite to the second power node; Multiple branch conductors extending from the inner conductor to the outer conductor, wherein the multiple branch conductors are uniformly distributed around the inner conductor in the radial coil network, and wherein a first branch conductor of the multiple branch conductors is electrically inserted between the first power node and the first ground node, and a second branch conductor of the multiple branch conductors is electrically inserted between the second power node and the second ground node; as well as A plurality of capacitors, wherein at least one of the plurality of capacitors is electrically inserted into each of the plurality of branch conductors, and wherein at least one of the at least one capacitor is a variable capacitor.

19. The device of claim 18, wherein the first RF power supply and the second RF power supply are different in frequency, phase or amplitude.

20. An inductively coupled plasma (ICP) process chamber for processing a substrate by plasma, the ICP process chamber comprising: The ICP process chamber has a chamber body, and the chamber body has a cover, a process volume, and a substrate support; A first RF power supply, the first RF power supply having a first frequency; A second RF power supply, the second RF power supply having a second frequency; and A radial coil network, having a planar structure, is positioned above the cover of the process chamber and configured to inductively generate plasma within the ICP process chamber, comprising: An inner conductor having an open center, wherein a first RF power supply is electrically connected to the inner conductor at a first power node, and a second RF power supply is electrically connected to the inner conductor at a second power node; An outer conductor, spaced apart from and surrounding the inner conductor, wherein a first grounding element is electrically connected to the outer conductor at a first grounding node opposite to the first power node, and a second grounding element is electrically connected to the outer conductor at a second grounding node opposite to the second power node; A plurality of branch conductors extending from the inner conductor to the outer conductor, wherein the plurality of branch conductors are uniformly distributed around the inner conductor in the radial coil network, and wherein a first branch conductor of the plurality of branch conductors is electrically inserted between the first power node and the first ground node, and a second branch conductor of the plurality of branch conductors is electrically inserted between the second power node and the second ground node; and A plurality of capacitors, wherein at least one of the plurality of capacitors is electrically inserted into each of the plurality of branch conductors, and wherein at least one of the at least one capacitor is a variable capacitor.

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