Systems and methods for VHF plasma processing

Abstract

The present disclosure relates to a plasma processing system for VHF plasma processing using a transmission antenna designed to achieve a resonant VHF standing wave inside a plasma processing chamber for manufacturing semiconductor devices. The system includes a transmission element capable of electromagnetically coupling to an incoming power line connected to a power source. The transmission element, the power transmission line, and the power source form a resonant circuit capable of achieving a VHF standing wave on the transmission element. The transmission element folds back onto itself to reduce the footprint of the antenna so that the (multiple) transmission elements can be located inside the plasma processing chamber. The transmission antenna has three parts, wherein a first part is electromagnetically coupled to the power transmission line, a second part is coupled to the plasma, and a third part is a folded part that reduces the footprint of the transmission element.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Non-Provisional Patent Application No. 16 / 357,731, filed on March 19, 2019, entitled “SYSTEM AND METHODS FOR VHF PLASMA PROCESSING,” which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to semiconductor processing equipment technology, and more particularly to an apparatus and method for controlling plasma for processing semiconductor substrates. Background Art

[0004] The geometry of microelectronic features continues to scale to smaller sizes and increase in complexity. Therefore, the patterning techniques used to manufacture microelectronic devices will become more precise to create smaller features on semiconductor substrates. Accurate patterning requires stricter control of processing parameters (such as ion and radical flux) at each point on the wafer so that a sufficient number of processed dies produce working chips, thereby making the process economically successful. One aspect of the patterning process includes using plasma to etch features to selectively remove materials from the substrate. One method of improving plasma etching technology involves controlling plasma in a predictable and uniform manner. For example, it is known that electromagnetic waves in the VHF frequency range (30 MHz to 300 MHz) can produce high-density plasma (referred to herein as "VHF plasma"). In addition, VHF plasma forms a relatively thin, low-energy sheath between the plasma edge and the substrate, which makes the ion acceleration of ions used to dynamically remove or etch the thin film on the substrate lower. Lower ion energy can improve selectivity and reduce damage to the underlying film. However, due to uneven spatial plasma distribution, VHF plasma processing has not been favored. This non-uniformity is due to the properties of VHF electromagnetic waves, which have wavelengths comparable to the size of the processing chamber, and the nonlinear interaction between the electromagnetic waves and the plasma. These characteristics make it difficult to obtain a uniform density distribution across the wafer, and to attempt to tailor the density distribution on a scale shorter than the wafer size; which is often desirable in order to compensate for non-uniformities caused by other causes such as gas distribution. Therefore, VHF systems and methods that improve plasma uniformity (e.g., spatial distribution) and enable control of plasma density distribution on length scales smaller than the wafer would be desirable. Summary of the invention

[0005] Disclosed herein are plasma processing systems and methods for microelectronic device manufacturing. In particular, for very high frequency (VHF) (e.g., 30 MHz to 300 MHz) electromagnetic waves, these VHF electromagnetic waves are used to ionize gases in a processing chamber or processing space (200 mm to 500 mm in size) that is comparable in size to a typical VHF wavelength (1000 mm to 10,000 mm). Generally, compared to low-frequency plasma generation techniques, VHF plasma processing is able to generate high-density plasma that forms a relatively thin, low-energy plasma sheath. The plasma sheath is observed as a potential difference between the substrate and the plasma, through which ions from the plasma are accelerated to interact dynamically with the substrate. Compared to non-VHF processing, the smaller sheath size achieved by VHF processing reduces the kinetic energy of the ions. Lower energy ions transfer less energy to the substrate, which can improve the etching selectivity between the overlying film and the underlying film, thereby improving the selectivity by maximizing the removal of the overlying film while removing as little of the underlying film as possible. Improved selectivity may enable patterning of smaller and / or more complex (eg, 3D structures) features on a substrate.

[0006] The systems and methods described herein are intended to remedy the spatial distribution problem by concentrating the effects of VHF energy within a smaller area or footprint using one or more plasma generating elements, each of which can be controlled individually or uniformly to ionize the gas within the processing chamber. The system includes a power transmission element disposed within the processing chamber, above the substrate holder, which is capable of forming (multiple) resonant circuits between (multiple) VHF power sources and resonant antennas disposed within the power transmission element. When power is applied to the resonant antenna, energy will be transferred to the gas flowing into the processing chamber to form a plasma (e.g., ionized gas), wherein the power includes a relatively high VHF frequency to obtain a relatively high plasma density and a smaller plasma sheath between the plasma and the substrate compared to low frequency excitation techniques (e.g., <30 MHz). Ions can be attracted to the plasma sheath and can be accelerated toward the substrate through the plasma sheath to interact dynamically with the substrate.

[0007] In one embodiment, the transmission element may include a pair of resonant antennas formed of a conductive material disposed within a dielectric material such that the antennas are not in physical contact with each other but may be electrically coupled to each other via a capacitive coupling component. The antenna(s) may be formed using conductive material arranged in an open loop, wherein portions of the antennas are capable of selectively coupling to both an incoming power source (e.g., a capacitive portion) and a gas within a processing chamber (e.g., an inductive portion) simultaneously. The inductive portion may be arranged parallel to a plasma processing region or substrate holder, while the capacitive portion is positioned opposite the inductive portion and is arranged to extend parallel to an incoming power transmission line that supplies power to the antennas.

[0008] In a particular embodiment, the capacitive portion can be folded back with one or more folds to reduce the total footprint of the antenna while maintaining a length sufficient to enable the antenna to form a resonant circuit with a VHF power source. In this way, the antenna folding enables a VHF antenna of relatively large electrical length to be placed in the processing chamber by using an antenna with a smaller footprint, horizontal surface area or volume. The antenna with a smaller footprint enables the use of relatively large wavelength VHF energy in a relatively small plasma processing area, which was not possible in the past. The resonant circuit can be formed at least in part based on a capacitive portion arranged or configured to be capacitively coupled to an AC power source that drives a current throughout the antenna. According to known resonance principles, the resonant circuit will amplify the incoming power signal to achieve a relatively high current in the antenna. The current driven through the inductive portion of the loop can be inductively coupled to the gas near the dielectric material because the coupling induces a current controlled by the current through the inductive portion of the loop in the ionized gas. In other words, the antenna can be designed to have sufficient length and / or size to form a resonant circuit with the VHF power source via coupling with a first portion of the loop (e.g., the capacitive portion) and orienting the location of a second portion of the loop (e.g., the inductive portion) within the dielectric material to couple the antenna to the process chamber gas to generate a plasma within the process chamber.

[0009] In one embodiment, a plasma processing chamber may include an AC power source that applies VHF energy to antennas disposed within a dielectric material, which form a resonant circuit between a resonant element and a power source when VHF energy is applied at a resonant frequency. In this way, the resonant element may generate an inductive field that is parallel to the plasma sheath, thereby allowing the field to penetrate into the plasma. Although the fields generated by the antenna and / or power source may penetrate into the plasma, these fields avoid surface modes having polarization perpendicular to the plasma sheath, which naturally propagate and disperse energy to portions of the reactor away from the antenna in an uncontrolled manner. In the past, the directional control problem could be solved by using higher amplitude energy, but higher amplitudes may drive the field into a nonlinear range, which increases process and hardware complexity, which eliminates the cost / quality advantage of using VHF plasma processing. By way of example and not limitation, the resonant element may include a conductive structure (e.g., a capacitor, an inductor, and a conduit portion) arranged in an open loop, which is embedded in a dielectric material that provides physical support for the conductive structure and isolates it from process chemicals during processing. For example, the dielectric component of the transmission element may include an exterior surface having a top surface and a bottom surface opposite the top surface, wherein the top surface is closest to the incoming VHF signal and the bottom surface is opposite the substrate holder within the plasma processing chamber. The dielectric component may include one or more transmission antennas embedded within the dielectric structure such that the transmission antenna is physically isolated from the exterior surface of the dielectric component because current does not flow directly from the power source through the dielectric material to the transmission antenna. Broadly speaking, in one embodiment, the transmission antenna may be an annular conductive structure including: a first portion of the transmission antenna opposite the bottom surface of the dielectric component (e.g., an inductive portion), a second portion of the transmission antenna opposite the top surface of the dielectric component (e.g., a capacitive portion); and a third portion of the transmission antenna disposed between and connected to the first portion and the second portion (e.g., a conduit portion). The first portion, the second portion, and the third portion of the transmission antenna may form a continuous conductive element such that current may flow between each portion when the transmission antenna is capacitively coupled to the power source.

[0010] In one embodiment, the transmission antenna can be arranged so that the first portion can be parallel to the bottom surface, the second portion can be parallel to the top surface, and the third portion can be disposed between the first portion and the second portion so that the third portion can be folded or oriented in a manner that reduces the footprint, area or volume surrounding the transmission antenna. In some cases, the third portion can have a longer length than the first portion or the second portion, but can be folded back onto itself to limit the footprint or horizontal surface area of ​​the third portion to the same or similar footprint as the first portion or the second portion. In a specific embodiment, the first portion has a conductive material having a length of at least 50 mm and a thickness of 10 μm to 100 μm. The folded portion of the transmission antenna is part of the continuous conductive structure of the transmission antenna, but can be separated by a dielectric material to avoid any overlapping or short circuits between the folded segments of the second portion of the antenna. The dielectric material may include any material that can maximize the avoidance of short circuits between the folded segments, which may include, but is not limited to, materials such as aluminum oxide, quartz, silicon carbide, or a combination thereof. In some cases, the dielectric material may have an yttrium oxide coating on at least one surface to minimize the chemical reactivity between the dielectric material and the process chemicals.

[0011] In another embodiment, two or more transmission antennas may be embedded in a dielectric component, and the combination of the transmission antenna and the dielectric component is referred to as a transmission element. The transmission antenna may include a coupling component disposed near each transmission antenna so that the coupling component may be electrically coupled to the transmission antenna or a capacitor may be formed between the transmission antennas, wherein the transmission antennas are in direct physical contact with each other or with the coupling component, or the transmission antennas are not in direct physical contact with each other or with the coupling component. The coupling component may enable the transmission antenna to be powered by one or more power supplies in a parallel or anti-parallel manner. For example, when the power applied to the transmission antenna is transmitted in phase (e.g., parallel), the transmit signal strength is amplified by the superposition principle, and similarly, when the incoming power to each transmission antenna is out of phase (e.g., anti-parallel), the transmit signal may be modulated. The capacitive coupling between the two transmission antennas breaks the polarization degeneracy, so that the parallel mode and the anti-parallel mode have different frequencies, and by selecting an appropriate combination of the two frequencies, the thickness of the ionized region in the processing chamber can be controlled. However, the processing chamber is not limited to using only one transmission element to control the plasma density or spatial distribution.

[0012] A plurality of transmission elements as described herein may be arranged together in a processing chamber to affect spatial distribution control and / or plasma density during substrate processing. For example, one or more transmission elements may be disposed in a plasma processing chamber having an internal volume and a power supply, wherein a substrate holder is disposed in the internal volume, and the power supply provides power to (multiple) power components relative to a portion of a transmission antenna. The power components may be designed and positioned to generate an electromagnetic field using current provided by the power supply so that the electromagnetic field induces a current in (multiple) transmission antennas. For example, the power supply may be electrically connected to a power component including one or more power antennas, which emit an electromagnetic field that can form a resonant circuit with the transmission antenna when power is applied at a specific resonant frequency. The resonant circuit is implemented at least in part based on the impedance of the transmission antenna or impedance matching between the transmission antenna, the power antenna, and the power supply. In most VHF embodiments, the combination of the power component and the transmission element is designed to achieve a resonant frequency when the power supply operates between 30 MHz and 300 MHz.

[0013] In a multiple transmission antenna embodiment, two or more transmission antennas may be disposed within a single dielectric component and arranged to be electrically coupled to each other via a coupling component disposed within the dielectric component. In one embodiment, the coupling component is a conductive element arranged to form a capacitor between the two transmission antennas. The coupling component may or may not be in physical contact with the transmission antenna. However, in a particular embodiment, the coupling component is separated from the transmission antenna by a dielectric material in which the transmission antenna is embedded.

[0014] The transmission elements disclosed herein can be used for any type of plasma processing, including but not limited to semiconductor substrates for manufacturing electrical devices, displays and / or solar panels. The method can be implemented on any substrate treated with plasma, which is generated by ionizing in a plasma chamber or applying electrical energy to a gas maintained at a sub-atmospheric pressure. In one embodiment, the substrate can be received in the plasma chamber and fixed to the substrate holder, while the plasma chamber is ready to receive process chemicals (e.g., gases) at a desired pressure, temperature and / or time. By applying electrical energy from a power source (e.g., an AC power source) coupled to the plasma processing chamber, energy can be introduced into the plasma chamber to induce a transmission current in a power transmission line relative to a transmission element or dielectric structure including one or more transmission antennas. The power transmission line and the transmission element are arranged so that the current of the power transmission line will induce a current in one or more transmission antennas based at least in part on the electric field caused by the transmission current in the power component. In some cases, a resonant circuit can be formed between the power supply, the power transmission line and the transmission antenna (multiple) based at least in part on the impedance of the transmission antenna (multiple) and the frequency (e.g., resonant frequency) of the electrical energy generated by the power supply. The resonance effect will amplify the incoming power to the transmission antenna to the gas in the process chamber, so that the field generated by the power transmission line has a lower amplitude than the amplitude of the electromagnetic field emitted by the transmission antenna(s). In most cases, the electromagnetic energy transmitted by the transmission antenna will have sufficient energy to ionize the gas disposed between the transmission antenna(s) and the substrate, wherein the ionized gas (e.g., plasma) is used to process the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings incorporated in this specification and constituting a part thereof show embodiments of the present invention and explain the present invention together with the general description of the present invention given above and the detailed description given below. In addition, the leftmost (multiple) digits of a reference number identify the drawing in which the reference number first appears.

[0016] Figure 1 is a diagram of a representative embodiment of a plasma processing system showing a schematic cross-sectional view of a plasma chamber including power components, transmission elements, and a substrate holder according to one or more embodiments of the present disclosure.

[0017] Figure 2 Included are side and top cross-sectional views of a power component having a power transmission line and a transmission element having a transmission antenna disposed within a dielectric structure according to one or more embodiments of the present disclosure.

[0018] Figure 3Included are top and side cross-sectional views highlighting the direction of current flow through the power antenna, each transmission antenna, and coupling components for the transmission antennas according to one or more anti-parallel embodiments of the present disclosure.

[0019] Figure 4 Included are top and side cross-sectional views highlighting the direction of current flow through the power antenna, each transmission antenna, and coupling components for the transmission antennas according to one or more parallel embodiments of the present disclosure. DETAILED DESCRIPTION

[0020] The following specific embodiments include exemplary embodiments that will fully reveal the general nature of the present disclosure so that others can easily modify and / or adjust these exemplary embodiments for various applications by applying the knowledge of technicians in (multiple) related fields without excessive experimentation and without departing from the scope of the present disclosure. Therefore, based on the teachings and guidance presented herein, such adjustments and modifications are intended to fall within the meaning of the exemplary embodiments and the scope of multiple equivalents. It should be understood that the phrases or terms herein are for descriptive and non-restrictive purposes, so that the terms or phrases of this specification will be interpreted by (multiple) technicians in the relevant fields according to the teachings of this article.

[0021] Figure 1 A plasma processing system 100 is depicted for processing a substrate using a plasma (not shown) formed by applying electromagnetic energy to a process chemical disposed within an interior volume of a plasma chamber 102. The process chemical may be introduced into the plasma chamber 102 via a gas delivery network 104, which may include a gas conduit integrated with a mass flow controller, a check valve, etc. to control the flow of gas into the plasma chamber 102. Additionally, a vacuum system 106 in fluid communication with the plasma chamber 102 may control pressure or gas flow in cooperation with the gas delivery network 104 by maintaining a sub-atmospheric pressure during plasma generation and removing byproducts from the processing process. By way of example and not limitation, the vacuum system 106 may include one or more pumps and control systems (e.g., a N2 ballast system, a butterfly valve system) to control the pressure within the plasma chamber 102.

[0022] Broadly speaking, plasma generation can be accomplished by applying electromagnetic energy (e.g., power source(s) 108) to an electrically neutral gas to release electrons from gas molecules, which become positively charged (e.g., ions) due to the loss of electrons. Ions can be characterized as molecules or atoms that are positively charged because the total number of electrons is not equal to the total number of protons. An electrically neutral gas can also generate molecular or atomic radicals (e.g., molecules or atoms that have at least one unpaired electron). In general, free radicals can be neutrally charged and can have a higher chemical reactivity relative to ions. Over time, the electromagnetic energy and increasing number of electron collisions within the gas mixture can increase the density of ionized molecules and free radicals within the gas mixture and can be used to process the substrate 110.

[0023] The plasma chamber system 100 can change certain process conditions to affect the amount of ions and / or radicals flowing toward the substrate, so that the ionized molecules can be affected by the potential difference within the plasma chamber 102. For example, the potential difference within the plasma chamber 102 can lead the ionized molecules (or atoms or radicals) to the substrate 110. The ions and radicals can interact with the substrate 110 and change the surface of the substrate 110 or remove a portion of the substrate 110 exposed to the plasma, or an overlying film. In some applications, the selectivity and control of plasma processing are important factors in the increasingly smaller feature sizes of patterned electronic devices. Lower ion energy can improve the selectivity between two overlying films on the substrate 110, so that the overlying film is fully removed while minimizing the removal or damage to the underlying film. One way to achieve higher etching selectivity is to use lower ion energy. This is achieved by minimizing the plasma sheath or barrier formed between the plasma and the surface of the substrate 110 when the net flux of electrons and ions reaches a steady state. For a given plasma density, if the plasma sheath is larger, the amount of energy that the ions obtain when passing through the sheath is greater. However, higher ion energies may result in more aggressive processes that are more difficult to control for selectivity and uniformity purposes. It is known that VHF plasma processing produces high-density plasma and relatively small plasma sheaths, thereby achieving lower ion energies. However, the properties of VHF plasma (e.g., high frequency) may result in non-uniform spatial plasma distribution based at least in part on propagating waves with wavelengths comparable to the processing chamber 102. Since the wavelength is comparable to the processing chamber size, the field on certain areas of the wafer (such as the center) is greater than the electromagnetic field at the edge of the wafer, resulting in similar non-uniformities in plasma density. On the other hand, the fact that the wavelength is comparable to the processing chamber size means that even if the phase of the wave can be adjusted so that the high field area is within the desired area, the length scale over which the plasma density can be controlled is comparable to the wafer size, and therefore local control cannot offset other non-uniformities caused by, for example, gas distribution, etching caused by product evacuation, non-uniform wafer temperature, or non-uniformities caused by earlier process steps that must be compensated. Therefore, the wavelength size makes it problematic to position the high density and small sheath effects in a controllable manner within the plasma chamber 102.

[0024] VHF plasma processing can be a practical alternative to existing processing techniques, using the systems and methods disclosed herein to achieve a controllable spatial density distribution and relatively small sheath size, thereby allowing low damage, high selectivity processing. The system can include an AC power source (e.g., (multiple) power sources 108) that applies VHF energy to form an electromagnetic field along (multiple) power components 114, which induces current in one or more antennas (not shown) within (multiple) transmission elements 116, which are disposed between the power components 114 and the substrate holder 118. The VHF energy can be applied at a resonant frequency to form a resonant circuit between the power components 114 and the transmission elements 116, thereby generating a plasma 120 and a corresponding plasma sheath 122 (not drawn to scale) opposite the substrate 110. The plasma sheath 122 is observed as a potential difference between the substrate 110 and the plasma 120, and acts to balance the flow of electrons and ions to the substrate 110. Ions are naturally accelerated through the sheath, but the final energy of the ions can be increased by using one or more biasing techniques (e.g., substrate holder biasing) to impart additional energy to accelerate ions through the plasma sheath 122 to kinetically interact with the substrate 110.

[0025] The resonant circuit formed between the power component 114 and the transmission element 116 can generate an induced field, wherein the electric field polarization is parallel to the plasma sheath edge 122, which allows the field to pass through the plasma and avoid surface modes having polarization perpendicular to the plasma sheath 122. Although the fields generated by the antenna and / or power supply can pass through the plasma, these fields avoid surface modes having polarization perpendicular to the plasma sheath 122, which may affect the directional control of the ions, thereby causing non-uniform etching on the substrate 110. In the past, the directional control problem can be solved by using higher amplitude energy, but higher amplitudes may drive the field into a non-linear range, which increases process and hardware complexity and eliminates the cost / quality advantages of using VHF plasma processing.

[0026] exist Figure 1In FIG, a cross-sectional view 124 of the plasma chamber 102 illustrates an embodiment of an electrical component 114 that enables electromagnetic energy (e.g., microwave energy, RF energy) and a gas mixture (not shown) to be transmitted into a region proximate to the substrate 110. The gas mixture can be introduced into the plasma processing region between the transmission element 116 and the substrate holder 118. The plasma processing region (e.g., plasma 120) can also receive energy from the VHF energy source 126 to induce a resonant response from the transmission element 116. The electromagnetic energy can include electromagnetic energy (e.g., radio frequency (RF) energy @<300 MHz) that can be transmitted from the VHF energy source 126 to the electrical component 114 via an electrical conduit (not shown). In FIG. Figure 1 In an embodiment, a single VHF energy source 126 drives a current through the power component 114, which generates a corresponding electromagnetic field around the power component 114, which can induce parallel currents in an antenna (not shown) in the transmission element 116. In this case, the single power component 114 can be designed to apply energy to multiple transmission elements 116. However, in other embodiments, multiple power components 114 can apply power to one or more transmission elements 114 depending on the desired application or degree of local plasma density or sheath size. Therefore, two or more VHF energy sources 126 can be arranged to apply power signals at different resonant frequencies depending on the impedance between the power component 114 and the transmission element 116 (e.g., antenna design), which will be in Figures 2 to 3 Described in the description.

[0027] In addition to the VHF energy source 126, the gas mixture in the plasma processing region may also receive electromagnetic energy from a second source (e.g., a bias power supply 128) that may bias the substrate holder 118 and / or the substrate 110 to affect the characteristics of the plasma near the substrate 110. In some embodiments, the bias power supply 128 and the VHF energy source 126 may be operated simultaneously or separately to generate the plasma 120 in the plasma processing region. In one embodiment, the bias power supply 128 may be an RF power supply that may provide more than 50 W of power at a frequency of 10 MHz or higher. The biasing of the substrate holder 118 and the power component 114 may be implemented using a controller 130 that may coordinate the process sequence to enable the generation of a plasma in the plasma processing region.

[0028] The controller 130 may use a computer processor 132 and a memory 134 to execute computer readable instructions that may be provided via an electrical communication network 136 to control components of the plasma processing system 100 (e.g., power supply 108, gas delivery device 104, etc.). The one or more computer processors 132 may include, but are not limited to, a central processing unit (CPU), a digital signal processor (DSP), a reduced instruction set computer (RISC), a complex instruction set computer (CISC), a microprocessor, a microcontroller, a field programmable gate array (FPGA), or any combination thereof. The memory 136 may include one or more computer readable storage media ("CRSM"). In some embodiments, the one or more memories may include non-transitory media such as random access memory ("RAM"), flash RAM, solid-state media, etc. Broadly speaking, the controller 130 may control the sequence of processing events to enable the generation of a plasma, or to switch between different types of plasmas that may be exposed to the substrate 110.

[0029] Figure 2 A side cross-sectional view 200 and a top view 202 of a combination of power components 114 and transmission elements 116 for generating plasma within the interior volume of the processing chamber 102 are included. In most cases, as Figure 2 As shown, the design and arrangement of these components is based, at least in part, on the ability to form a resonant circuit that amplifies an incoming VHF power signal from one or more power sources 108 (e.g., VHF energy source 126) that interacts with the process chemistry to generate a plasma of high density and low ion energy to process the microelectronic substrate 110 disposed on the substrate holder 118. Generally, a resonant condition exists when the capacitive reactance and the inductive reactance of the circuit are equal in magnitude, so that the evanescent magnetic field from the inductive element (e.g., power component 114) generates a current that charges the capacitive element (e.g., transmission element 116) of the circuit, and the process repeats because the alternating current generates an oscillating magnetic field in the inductive element (which drives a corresponding charging of the capacitive element).

[0030] Turning to the cross-sectional view 200, it is intended to illustrate a cross-section through one of the transmission elements 116, which includes a transmission antenna 206a and a corresponding power transmission line 204a of the power component 114. The transmission antenna(s) 206a and the power transmission line(s) 204a are designed and arranged to be electromagnetically coupled to each other, such that a magnetic field generated by an alternating current through the power transmission line 204 induces an opposing current in the transmission antenna(s) 206a. The power transmission line 204a may be electrically or physically isolated from the transmission element 116 by an insulating structure 208 formed or disposed around or near the power transmission line 204. The insulating structure 208 may be made of any non-conductive material that allows current to flow through the power transmission line 204 in a controlled and / or predictable manner (e.g., without shorting to the transmission element 116). However, the insulating structure will still allow electromagnetic coupling between the power transmission line 204 and the corresponding transmission antenna 206a. Similarly, the transmission antenna 206a can be disposed within a dielectric structure 210 that physically isolates the transmission antenna 206a from the power component 114 so that the current flowing through the power transmission line 204a does not flow through the transmission antenna 206a. However, the dielectric structure 210 and the insulating structure 208 are designed and arranged so that the magnetic field around the power transmission line 204a generated by the current passing through the power transmission line 204a can induce a current in the transmission antenna 206a. The dielectric structure 210 can be made of any dielectric material that electrically isolates the transmission antenna 206a from the power transmission line 204a but enables the magnetic field generated by the power component 114 to induce a current in the transmission antenna 206a. For example, the dielectric structure 210 can be made of aluminum oxide, quartz, silicon carbide, or a combination thereof, and can include an yttrium oxide coating on at least one surface (e.g., an exposed surface 212) that may be exposed to plasma or process chemicals during substrate processing. In one embodiment, the exposed surface 212 may be a portion of the dielectric structure 210 opposite the substrate holder 118 or a portion opposite the interface 214 between the insulating structure 208 and the dielectric structure 210. Figure 2 In an embodiment, the interface 214 does not include an air gap or intervening layer between the power component 114 and the transmission element 116, but in other embodiments, an air gap or intervening layer may be present to enhance electrical isolation or to isolate the power component 114 from plasma or process chemicals.

[0031] In addition, the design and arrangement of the power component 114 and the transmission antenna 206a are intended to achieve a resonant condition that amplifies the electromagnetic fields near the transmission antenna 206a, which are generated by the electromagnetic power emitted from the (multiple) power sources 108 and coupled by the power component 114. The resonant condition may exist at least in part based on a combination of one or more design criteria, which may include, but are not limited to: the impedance of the transmission antenna 206a, the impedance of the power transmission line 204, the operating frequency of the VHF power source 126, and / or the dielectric constant of the insulation structure 208 and the dielectric structure 210. Impedance is an indication of the resistance or reactance of a conductive element to the flow of alternating current. More specifically, in Cartesian form, impedance can be considered as the resistance of a circuit and the resistance of a circuit to changes in current or voltage, which resistance is based at least in part on the inductance or capacitance of the circuit (e.g., the power transmission line 204, the transmission antenna 206a, etc.). Therefore, the impedance depends on the size, shape, and composition of the circuit components, but may also be affected by the rate of change of current and voltage within the circuit. Thus, impedance is a reflection of the physical design and operating conditions of the circuit, which can be measured as opposition to voltage changes (e.g., capacitive reactance) and opposition to current changes through the circuit (e.g., inductive reactance). Under resonant conditions, the capacitive reactance and inductive reactance of the circuit are equal in magnitude, so that the evanescent magnetic field from the inductive element (e.g., power component 114) generates a current that charges the capacitive element (e.g., transmission element 116) of the circuit, and the process repeats because the alternating current generates an oscillating magnetic field in the inductive element. Typically, the resonant condition is achieved at a specific resonant frequency (e.g., the operating frequency of the power supply 108) that creates the resonant condition in a predictable and controllable manner. As a result of the resonant condition, the amplitude of the electromagnetic field emitted from the resonant circuit (e.g., transmission antenna 206a, power transmission line 204a, VHF energy source 126) will be greater than the amplitude of the incoming power signal to the power component 114. However, as will be appreciated by those of ordinary skill in the art, other design considerations may be considered in many transmission element 116 embodiments.

[0032] For example, in addition to impedance, design considerations for the resonant circuit should also take into account the wavelength of the incoming power, such that the length of the transmission antenna 206 can be as long as the incoming 1 / 4 wavelength, 1 / 2 wavelength, or full wavelength. In VHF applications (e.g., 30 MHz to 300 MHz), the length of the transmission antenna 206a can range between 250 mm to 2500 mm for 1 / 4 wavelength applications, 500 mm to 5000 mm for 1 / 2 wavelength applications, and up to 10,000 mm for full wavelength applications. Therefore, in some cases, the length of the transmission antenna 206 may be greater than the diameter of the processing chamber 102 if arranged end to end. However, this problem can be remedied by distributing or arranging the transmission antenna 206 within the dielectric structure 210 so that a relatively long transmission antenna 206a can be disposed within the processing chamber 102 despite the length being greater than the diameter of the processing chamber 102. For example, the transmission antenna 206a may include a continuous antenna having several portions deposited or embedded within the dielectric structure 210 so that current can flow along each portion of the transmission antenna 206a that bends back onto itself, such as Figure 2 These portions may be arranged to include a portion of the transmission antenna 206a capable of directly electromagnetically coupling to the power transmission line 204a (thereby inducing a current in the transmission antenna 206a), a portion of the transmission antenna 206a capable of ionizing the gas in the processing chamber 102, and a portion of the transmission antenna 206a for connecting the above two portions together, wherein the combination of these portions provides a length sufficient to allow the transmission antenna 206a to form a resonant circuit with the VHF signal.

[0033] For example, Figure 2 As shown, the transmission antenna 206a may include a first portion 220 opposite to the bottom surface 222 of the dielectric structure 210, a second portion (e.g., a first coupling portion 224a, a second coupling portion 224b) opposite to the top surface 216, and a third portion (e.g., a first outer portion 226a, a second outer portion 226b, a first inner portion 226c, and a second inner portion 226d) disposed between the first portion 220 and the second portion. These portions may be arranged in various designs and configurations such that the total length of the combined and / or continuous portions will enable the VHF standing wave disposed along the transmission antenna 206a to reside completely within the processing chamber 102. In this particular embodiment, as shown in FIG. Figure 2As shown, the first portion 220 of the transmission antenna 206a extends in a continuous manner in a plane opposite to and / or parallel to the bottom surface 222, with a first end connected to the first outer portion 226a, and an opposite end connected to the second outer portion 226b of the transmission antenna 206a, and respective ends of the first coupling portion 224a and the second coupling portion 224b are electrically connected or paired with respective ends of the first outer portion 226a or the second outer portion 226b, wherein opposite ends of the coupling portions are connected to respective ends of the first inner portion 226c and the second inner portion 226d of the transmission antenna 206a, as shown. Figure 2 In this embodiment, the inner portions 226c, 226d are symmetrical to each other along a vertical axis disposed between the two portions, but in other embodiments this is not required, and portions of the inner portions are bent back onto each other to obtain sufficient total transmission antenna 206a length to obtain a VHF standing wave within the transmission element 116. However, Figure 2 The illustrated embodiment is merely exemplary, and the scope of the present disclosure should not be limited to this particular embodiment.

[0034] In some embodiments, the waveguide element 228 can be disposed between the curved portions of the first inner portion and / or the second inner portion 226c, 226d to guide electromagnetic waves propagating along the transmission antenna 206a. In one example, the waveguide element 228 can be made of a conductive material similar to the transmission antenna 206a, or alternatively, made of a material different from the transmission antenna 206a. The length and orientation of the waveguide element depends on the design of the first inner portion 226c and the second inner portion 226d, and can be disposed between the third portion and / or the longer different portion located between the first portion 220 and the second portion. However, the combined length of the first portion, the second portion, and the third portion of the transmission antenna 206 is based at least in part on forming a resonant circuit or matching impedance between the transmission antenna 206a, the power antenna 204a, and the power source 108, which can apply energy to the power antenna 204a at a frequency of 30 MHz to 300 MHz.

[0035] exist Figure 2 In embodiments, the first portion 220 is closest to the process chemistry or plasma 120, and the electromagnetic field radiated from the first portion 220 can ionize any process chemistry disposed within the plasma chamber 102 during processing. The size of the first portion 220 can range between 50 mm and 500 mm, depending on the size of the substrate 110, the processing chamber 102, and / or the desired resonant conditions (e.g., transmission element impedance, source frequency). In most embodiments, the length of the first portion will be between 200 mm and 400 mm, but in one particular embodiment, the first portion 220 will be approximately 350 mm. However, Figure 2The embodiments are for purposes of explanation, and in certain larger substrate applications (such as flat panel displays or other industrial applications), the length of the first portion may be greater than 500 mm.

[0036] In some embodiments, the transmission element 116 may be configured as follows Figure 2 206a, 206b, wherein each transmission element 116 has the same or similar design. For purposes of illustration and explanation, the top view 202 does not include the insulating structure 208 of the power component 114, and the dielectric structure 210 is shown as transparent to show the details of the transmission antennas 206a, 206b, the waveguide 228, and the first and second coupling interfaces (e.g., 230a, 230b).

[0037] exist Figure 2 In an embodiment, the transmission antennas 206 may be adjacent to each other and may be electromagnetically coupled to each other using one or more coupling interfaces (eg, a first coupling interface 230a, a second coupling interface 230b). Figure 2 In an embodiment, the transmission antennas 206 are placed adjacent to each other and parallel to each other along their lengths, wherein the coupling interfaces 230a, 230b extend vertically from below the transmission antennas 206a, 206b, so that the coupling interfaces 230a, 230b form parallel plate capacitors with the transmission antennas 206a, 206b. The first coupling interface 230a extends from below the first inner portion 226c of the first transmission antenna 206a to reach below the first inner portion (not shown in the top view 202) of the second transmission antenna 206b. Similarly, the second coupling interface 230b extends from below the second inner portion 226d of the first transmission antenna 206a to reach below the second inner portion (not shown in the top view 202) of the second transmission antenna 206b. In this embodiment, the transmission antennas 206a, 206b can be coupled to each other by simultaneously forming parallel plate capacitors between the respective coupling interfaces 230a, 230b and the transmission antennas 206a, 206b.

[0038] The coupling interfaces 230a, 230b enable the electromagnetic energy of each of the transmission antennas 206a, 206b to interact to modulate the electromagnetic energy exposed to the process chemicals at the bottom surface 222 and / or in the processing chamber 102 via the superposition theorem. The first coupling interface 230a and the second coupling interface 230b form the basis of the coupling components embedded in the dielectric structure 210. The coupling components or interfaces can be made of conductive materials similar to or different from the transmission antenna 206a. In Figure 1 In another embodiment, each transmission element 116 is powered by a separate power source 108 and receives electromagnetic energy from its own corresponding power transmission line 204 (eg, a power transmission antenna).

[0039] Figure 3 and Figure 4 Shown Figure 2 202 of FIG. 10 . In this embodiment, the corresponding power source 108 applies electromagnetic energy to each of the transmission antennas 206a, 206b in a complementary mode or a non-complementary mode to modulate the energy transmitted from the transmission element 116. For example, when the current flowing through each transmission antenna 206a, 206b flows in the same direction (e.g., parallel to each other), a complementary interaction occurs, so that electromagnetic energy of similar frequency and / or phase is integrated together as understood from the superposition theorem to generate a wave of higher amplitude. In this case, the current flowing through the two parts 220 of its corresponding transmission antenna 206 produces a substantially mutually reinforcing electromagnetic field, and thus reaches the gap containing the plasma. In a non-complementary interaction, the current flows through each transmission antenna 206a, 206b in opposite directions (e.g., anti-parallel to each other), so that the two electromagnetic waves can have the same frequency and / or amplitude, but not the same phase angle. In this case, the interaction of the waves modulates or attenuates the electromagnetic energy reaching the process chemical, so that the distribution or uniformity of the energy can be modulated or adjusted as needed. In this case, the currents flowing through the respective portions (e.g., the first portion 220) of their corresponding transmission antennas 206a, 206b flow in opposite directions, and thus the electromagnetic fields generated by these currents are substantially opposite to each other. No net field is generated at a distance away from the two transmission antennas 206a, 206b, and thus these fields are more strictly confined to the area close to the transmission element 116.

[0040] Figure 3 An example of non-complementary interaction between dual transmission antennas (e.g., first transmission antenna 206a, second transmission antenna 206b) is shown. As seen in the top view 300, anti-parallel power signals are introduced into the power transmission lines (e.g., first power transmission line 204a, second power transmission line 204b), which can similarly induce anti-parallel currents between the two transmission antennas 206a, 206b, and the anti-parallel currents flow in the corresponding coupling interfaces (e.g., first coupling interface 230a, second coupling interface 230b). As shown in the top view 300, the incoming current from the power source 108 is in the opposite direction because the first power current 302a flows in the opposite direction to the second power source current 302b. Similarly, the currents induced in the corresponding transmission antennas (first transmission antenna 206a, second transmission antenna 206b) by the current in the power transmission lines (first power transmission line 204a, second power transmission line 204b) will be in the opposite direction.

[0041] Steering Figure 3300, a first cross section 304 of the first transmission element 206a represents viewing the element as shown via the AA-AA cross section line shown in the top view 300. Similarly, a second cross section 306 of the second transmission element 206b represents viewing the element via the BB-BB cross section line shown in the top view 300. Figure 3 and Figure 4 A third angle projection convention is used for these section lines. In the first section 304, a first power current 302a flows through the first power transmission line 204a, thereby generating an electromagnetic field (not shown) that induces a first transmission current 308a flowing through the first transmission antenna 206a, and the current will oscillate in a similar manner to the first power current 302a. Similarly, a second power current 302b flowing in the opposite direction of the first power current 302a will induce a second transmission current 308b flowing through the second transmission antenna 206b in the opposite direction or anti-parallel direction. In this way, the combination of the two AC power signals generates an oscillating potential difference between the first transmission antenna 206a and the second transmission antenna 206b, which affects the capacitive coupling between the transmission elements 206a, 206b via the coupling interfaces 230a, 230b, so that the current induced in the first coupling interface 230a and the second coupling interface 230b also oscillates in opposite directions, thereby forming an oscillating electromagnetic field (e.g., a first coupling field 310a, a second coupling field 310b) along each coupling interface. The arrow convention is used to represent the direction of the RF current in the coupling elements 230a and 230b, while the current has the direction shown by the arrows above 308a and 308b. The dot in the circle indicates that the current is flowing out of the plane of the drawing toward the observer, and the cross in the circle indicates that the current is flowing into the plane of the drawing away from the observer. Therefore, referring to the cross section AA, the first transmission current 308a flows downward along the first transmission antenna 206a element directly above the first coupling interface 230a, wherein the current 308a induces a current in the first coupling interface 230a, thereby generating a first coupling field 310a around the first coupling interface 230a in a counterclockwise direction. Therefore, based on the current flowing in the opposite direction of the first coupling interface 230a, a second coupling field 310b around the second coupling interface 230b in a clockwise direction is formed.

[0042] Figure 4Demonstrating an example of complementary interaction between dual transmission elements (e.g., first transmission antenna 206a, second transmission antenna 206b), as seen in top view 300, parallel power signals are introduced into the power transmission lines (e.g., first power transmission line 402a, second power transmission line 402b). Because the currents are parallel to each other in this case, no current flows in coupling elements 230a and 230b. As shown in top view 400, the incoming currents from power source 108 are in the same direction (e.g., first parallel power current 402a, second parallel power current 402b). Likewise, the currents induced in the corresponding transmission antennas (first transmission antenna 206a, second transmission antenna 206b) by the power transmission line currents will be in the opposite direction to the currents flowing through power transmission lines 402a, 402b.

[0043] Steering Figure 4 400, a first cross section 404 of the first transmission antenna 206a represents viewing the element as shown via the CC-CC cross section line shown in the top view 400. Similarly, a second cross section 406 of the second transmission antenna 206b represents viewing the element via the DD-DD cross section line shown in the top view 400. In the first cross section 404, the first power current 402a flows through the first power transmission line 204a, thereby generating an electromagnetic field (not shown) that induces a first parallel transmission current 408a flowing through the first transmission antenna 206a, and the current will oscillate in a similar manner to the first parallel current 402a. Similarly, the second parallel current 402b flowing in the same direction as the first parallel current 402a will induce a second parallel transmission current 408b flowing through the second transmission element 206b in the same direction or parallel direction. Because the current flows in the same direction in the transmission antennas 206a and 206b, there is no current in the coupling elements 230a and 230b. Therefore, the current parallel and current anti-parallel resonance modes have different resonance frequencies. Furthermore, the fields generated beneath the paired transmit antennas 206a and 206b are different, extending farther from the element in the case of parallel current than in the case of antiparallel current. The distance that the field penetrates into the plasma can be affected by exciting the structure at the correct frequency to excite the desired parallel and antiparallel modes. Because Maxwell's equations are linear, the two solutions can be superimposed, and thus the two modes can be excited simultaneously to varying relative degrees relative to each other, so that the extent to which the field penetrates into the plasma varies continuously.

[0044] The following detailed description refers to the accompanying drawings to illustrate exemplary embodiments consistent with the present disclosure. References to "one embodiment," "embodiment," "exemplary embodiment," etc. in the detailed description indicate that the exemplary embodiment described may include a particular feature, structure, or characteristic, but not necessarily every exemplary embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Further, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, whether or not explicitly described, (multiple) technicians in the relevant field should know that such feature, structure, or characteristic can be affected by combining with other exemplary embodiments.

[0045] As used herein, "substrate" or "microelectronic substrate" generally refers to an object that is processed according to the embodiments described herein. A microelectronic substrate may include any material portion or structure of a device (particularly a semiconductor or other electronic device), and may be, for example, a base substrate structure (such as a semiconductor substrate), or a layer (such as a thin film) on or overlying a base substrate structure. Therefore, a substrate is not intended to be limited to any particular infrastructure, underlying layer, or overlying layer, patterned or unpatterned, but is contemplated to include any such layer or infrastructure, and any combination of layers and / or infrastructures. The following description may refer to a specific type of substrate, but this is for illustrative purposes only and not for limiting purposes.

[0046] The exemplary embodiments described herein are provided for illustrative purposes and are not restrictive. Other embodiments are possible, and the exemplary embodiments may be modified within the scope of the present disclosure. Therefore, the specific embodiments are not intended to limit the present disclosure. On the contrary, the scope of the present disclosure is limited only by the appended claims and their equivalents.

[0047] It should be understood that the detailed description section, rather than the abstract section, is intended to be used to interpret the claims. The abstract section may set forth one or more but not all exemplary embodiments of the present disclosure, and therefore, is not intended to limit the present disclosure and the appended claims in any way.

[0048] Although the present disclosure has been illustrated by the description of one or more embodiments thereof, and although these embodiments have been described in considerable detail, these embodiments are not intended to define or in any way limit the scope of the appended claims to such details. Additional advantages and modifications will readily occur to those skilled in the art. The present invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Therefore, departures from these details may be made without departing from the scope of the overall inventive concept.

Claims

1. A device for processing, comprising: a plasma processing chamber comprising an interior volume, a substrate holder disposed within the interior volume, and a power source disposed outside the interior volume; a power component coupled to the plasma processing chamber, the power component comprising one or more power transmission lines electrically connected to the power supply; a transmission element disposed between the power component and the substrate holder, the transmission element being electrically insulated from the one or more power transmission lines and arranged adjacent to at least one of the one or more power transmission lines to allow electromagnetic coupling between the at least one power transmission line and the transmission element, the transmission element comprising: a dielectric structure comprising a surface opposite the substrate holder; and a transmission antenna having a total length configured to achieve a standing wave having a frequency of 30 MHz to 300 MHz and being embedded in the dielectric structure such that the dielectric structure blocks current from flowing from the at least one power transmission line to the transmission antenna but allows electromagnetic coupling between the at least one power transmission line and the transmission antenna, wherein the transmission antenna includes a conductive structure folded to form an open loop including a plurality of vertical portions of the transmission antenna, the plurality of vertical portions extending in a vertical direction from the power component to the substrate holder.

2. The device according to claim 1, wherein: The power component includes two or more power transmission lines electrically coupled to the power source.

3. The device of claim 2, wherein: The transmission antenna includes two or more transmission antennas arranged to be electromagnetically coupled with corresponding power transmission lines.

4. The device of claim 1, wherein: The dielectric structure includes aluminum, quartz, silicon carbide, or a combination thereof.

5. The device of claim 1, wherein: The dielectric structure includes an yttrium oxide coating on at least one surface.

6. The device of claim 1, wherein: The transmission antenna comprises two or more transmission antennas arranged to be electromagnetically coupled with corresponding power transmission lines of the power component, and the dielectric structure comprises a coupling component embedded within the dielectric structure, the coupling component comprising a conductive element arranged to form a capacitor between the two transmission antennas.

7. The device of claim 1, wherein: The transmission antenna includes a length based at least in part on forming a resonant circuit between the power transmission line and the transmission element when the power source applies energy to the power transmission line at a frequency of 30 MHz to 300 MHz.

8. The device of claim 7, wherein: The resonant circuit is based at least in part on an impedance of the transmission antenna.

9. The device of claim 1, wherein: The transmission antenna includes a length based at least in part on impedance matching between the transmission antenna, the one or more power transmission lines, and the power source.

10. The device of claim 1, wherein: The power supply includes an operating frequency range of 30MHz to 300MHz.

11. The device of claim 1, wherein: The plasma processing chamber includes two or more transmission elements.

12. The apparatus of claim 1, wherein: The transmission element includes an outer surface including a top surface and a bottom surface opposite the top surface, and The transmission antenna is electrically isolated from the external surface, and includes a first portion opposite to the bottom surface, a second portion opposite to the top surface, and a third portion disposed between the first portion and the second portion.

13. The apparatus of claim 12, further comprising a coupling component embedded within the transmission element, the coupling component comprising a conductive element arranged to form a capacitor between at least two of the transmission antennas.

14. The apparatus of claim 12, wherein: The first portion comprises a length of at least 50 mm.

15. The apparatus of claim 12, wherein: The transmission antenna forms a continuous conductive element at least partially based on the first portion, the second portion and the third portion of the transmission antenna.

16. The apparatus of claim 12, wherein: The transmission antenna includes a conductive material having a thickness of 10 μm to 100 μm.

17. The apparatus of claim 12, wherein: The first portion is parallel to or opposite to the bottom surface, and the second portion is parallel to or opposite to the top surface.

18. The apparatus of claim 17, wherein: The parallel or opposing region of the second portion is separated from the first portion by a dielectric material.

19. The apparatus of claim 12, wherein: The transmission element includes a gas conduit extending from the top surface to the bottom surface.

20. The apparatus of claim 1, wherein: The conductive structure further includes a plurality of horizontal portions extending in a direction along the surface of the substrate holder, at least two of the plurality of horizontal portions being disposed at different distances from the substrate holder along the vertical direction, and Each vertical portion is connected to at least one of the horizontal portions by at least one fold.

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