Spatially tunable inductively coupled plasma antenna

Abstract

This specification describes an apparatus comprising an inductively coupled plasma (ICP) antenna having a plurality of inductances electrically coupled in series, and a capacitor coupled in parallel with one of the plurality of inductances. The ICP antenna will be electromagnetically coupled to a plasma.

Description

Technical Field

[0001] Claim of Priority: This application is a continuation of, and claims the benefit of priority of, U.S. Patent Application No. 63 / 363,191, entitled "SPATIALLY TUNABLE INDUCTIVELY COUPLED PLASMA ANTENNA", filed on April 19, 2022, the entire disclosure of which is incorporated herein by reference.

Background Art

[0002] Process tools are used to perform processes such as film deposition and etching on semiconductor wafer substrates. These process tools can utilize plasma for plasma-enhanced etching and deposition processes. The plasma can be formed and maintained by an inductive electric field generated and controlled by a coil outside the chamber. These coils are coupled to a high-frequency voltage source. To enable process uniformity, it is useful to control plasma parameters that can affect deposition and etching characteristics. Process uniformity can help create semiconductor devices with uniform device characteristics across the substrate. However, as the requirements for the performance and stability of semiconductor devices within the substrate increase, it is desired to develop features in inductively coupled plasma coils that can improve local plasma characteristics on the substrate.

Summary of the Invention

[0003] The materials described in this specification are illustrated by way of example in the accompanying drawings and not by way of limitation. For purposes of simplification and clarification of the illustration, the elements shown in the figures are not necessarily drawn to scale or in exact position. For example, the dimensions of some elements may be exaggerated relative to other elements for clarity. Also, for purposes of clarification of the description, various physical features may be represented in their simplified “idealized” forms and geometric shapes, but it should be understood that actual implementations may only approximate the ideal shown. For example, smooth surfaces and square intersections may be drawn ignoring the finite roughness, rounded corners, and intersections of imperfect angles that are characteristics of structures formed by nanofabrication techniques. Further, where appropriate, reference labels are repeated between figures to indicate corresponding or similar elements.

Brief Description of the Drawings

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[0014] In at least one embodiment, an apparatus and method are disclosed that enable spatial alignment of the radial profile of an inductively coupled plasma (ICP) using a single ICP antenna. Here, numerous specific details, such as structural schemes, are described to provide a complete understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that the embodiments of the present disclosure can be practiced without these specific details. In other cases, well-known features, such as gas feed line pipe joints, heating elements, and snap switches, are not described in particular detail so as not to obscure the embodiments of the present disclosure. Further, it should be understood that at least one embodiment shown in the figures is an exemplary representation and is not necessarily drawn to scale.

[0015] In some cases, to avoid obscuring at least one embodiment, well-known methods and devices are shown in block diagram form rather than in detail. Throughout this specification, references to "one embodiment" or "an embodiment" or "at least one embodiment" or "some embodiments" mean that a particular feature, structure, function, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of "in one embodiment" or "in an embodiment" or "at least one embodiment" or "some embodiments" in various places throughout this specification are not necessarily referring to the same embodiment. Further, the particular features, structures, functions, or characteristics can be combined in any suitable manner in at least one embodiment. For example, a first embodiment may be combined with a second embodiment, provided that the particular features, structures, functions, or characteristics associated with the first and second embodiments are not mutually exclusive.

[0016] Here, "coupled" and "connected", along with their derivatives, can be used to describe a functional or structural relationship between components. These terms are not intended to be synonyms of each other. Rather, in certain embodiments, "connected" can be used to indicate that two or more elements are in direct physical, optical, or electrical contact with each other. Here, "coupled" can be used to indicate that two or more elements are in direct or indirect (with other elements intervening therebetween) physical, electrical, or magnetic contact with each other, and / or that two or more elements cooperate or interact with each other (e.g., in a cause-and-effect relationship).

[0017] Here, "on", "under", "between", and "upon" can generally refer to the relative position of one component or material with respect to another component or material where such a physical relationship is worthy of note. Unless these terms are modified by "direct" or "directly", one or more intervening components or materials may be present. A similar distinction is also made with respect to component assemblies. As used throughout this specification and the claims, the terms "at least one of" or "one or more of" in connection with a list of items can mean any combination of the listed terms.

[0018] Here, "adjacent" generally can refer to the position of an object that is next to (e.g., immediately next to or near, with one or more objects in between) or in proximity to (e.g., abutting) another object.

[0019] Unless otherwise specified in the explicit context in which they are used, "substantially equal", "nearly equal", and "approximately equal" generally can mean that there are only incidental variations between two things so described. In at least one embodiment, such variations are within + / - 10% of the reference value.

[0020] In a process tool provided for a plasma enhanced process, spatial control of plasma characteristics such as the density and energy of charged species, often referred to as plasma density, and the temperature of electrons or ions, is desirable to obtain control of the local etching rate or deposition rate on a substrate. In at least one embodiment, the radial distribution of the plasma density or the density of reactive species in the plasma can be controlled by spatially controlling the RF power coupled to the plasma. The RF power coupling can then be controlled by adjusting an antenna coil or antenna coil elements. In at least one embodiment, a process tool such as a plasma process tool can include a chamber with an inductively coupled plasma (ICP) antenna coil coupled to a radio frequency (RF) signal source. In at least one embodiment, an ICP antenna is utilized to generate an electromagnetic field, and this electromagnetic field generates an induced electric field through the action of a transformer that sustains the plasma.

[0021] In at least one embodiment, a spatially tuned plasma density can increase the deposition rate or etching rate towards the periphery of the substrate being processed. For this purpose, several solutions have been developed to tune the magnetic field in a particular region of the plasma compared to other regions. Some approaches use a plurality of spatially separated coils and a plurality of RF signal sources. Other solutions include a plurality of coils and multiple outputs from a single source. Another approach is to split the power from a single source output, and the power can be sent to multiple coils at different power levels. Other approaches include a movable segment of an ICP antenna coil that spatially varies the coupling by changing the distance of the coil segment to the plasma. Most of these approaches may use fairly costly, sophisticated, and bulky equipment.

[0022] To address the limitations described herein, in at least one embodiment, a spatially tunable inductively coupled plasma (ICP) antenna is provided. In at least one embodiment, the spatially tunable ICP antenna comprises a plurality of individual inductances or distributed inductances (e.g., segments of a single coil) coupled in series. In at least one embodiment, the plurality of inductances are segments of a coil. In at least one embodiment, one or more of the inductances may be coupled in parallel with a shunt capacitor. In at least one embodiment, the parallel combination of an inductance (L) and a shunt capacitor (C) forms an LC tank circuit. In at least one embodiment, the tank circuit has a resonant frequency determined by the values of the inductance and capacitance. In at least one embodiment, the tank circuit comprising a portion of the coil may be the tunable portion of the ICP antenna, and tuning may be achieved by varying the capacitance, inductance, frequency, or any combination of tuning parameters. In at least one embodiment, the portion of the coil not coupled to a capacitor (or capacitance) may be considered the untuned portion of the coil. In at least one embodiment, the spatially tunable ICP antenna is coupled to a radio frequency (RF) signal source (hereinafter, RF source) configured to drive current at a high frequency, and feeds RF power to the ICP antenna.

[0023] In at least one embodiment, at some applied RF frequencies (or tuned capacitor values at a constant frequency), one or more tuned portions on the ICP antenna can resonate and generate a large circulating current in the associated tank circuit. In at least one embodiment, the large circulating current can generate a spatially distinct magnetic field across the entire ICP antenna. In at least one embodiment, the tuned portion of the ICP antenna can generate a very strong magnetic field at some applied RF frequencies compared to adjacent untuned portions of the ICP antenna where a smaller line current can flow. In at least one embodiment, the magnetic field emitted from the untuned portion may be weaker than the magnetic field emitted from the tuned portion of the IC antenna. In at least one embodiment, the relative magnitudes of the magnetic field strengths in the tuned and untuned portions of the ICP antenna can correlate with the ratio of the applied RF frequency f to the resonance frequency f 0 of the tuned portion.

[0024] In at least one embodiment, when utilized in a plasma processing tool, a spatially tunable ICP antenna can enable tuning of the radial distribution of plasma density in an inductively coupled plasma. In at least one embodiment, local spatial enhancement of the inductively coupled plasma in a selected region is possible by tuning the source frequency, or the resonance frequency of the tuned portion of the ICP antenna. In at least one embodiment, local enhancement of the radially distributed portion of the plasma can be equivalent to an increase in the plasma-assisted etching or deposition rate of the corresponding region of the substrate. In at least one embodiment, an increase in the deposition rate of a PECVD (plasma-enhanced chemical vapor deposition) or PEALD (plasma-enhanced atomic layer deposition) process can be enabled in these same regions of the substrate.

[0025] Here, a "coil" generally may refer to a form of inductance comprising a wire or other conductor wound circularly one or more times. In at least one embodiment, the coil may be in the form of a flat spiral or in the form of a solenoid adjacent to a flat or dome-tapered dielectric window. In at least one embodiment, geometric factors such as the number of turns, the spacing between turns, the diameter and length of the coil, as well as other dimensions such as the thickness of the wire and the distance from the wire to the plasma may also affect the inductance of the coil.

[0026] Here, a "coil segment" generally may refer to a part of a coil. In at least one embodiment, the coil segments may be continuous with adjacent coil segments within the coil.

[0027] Here, a "terminal" generally may refer to the end of a conductor or electrical component, such as a wire, that can serve as a connection point to another conductor or electrical component. In at least one embodiment, in the case of a coil, the terminal is at the end of the winding. In at least one embodiment, with respect to a coil segment, the coil segment can have terminals at the beginning and end of the coil segment conductor.

[0028] Here, "inductance" generally can refer to a passive electrical device that stores magnetic energy from a flowing current. In at least one embodiment, the inductance can comprise a conductor (e.g., a metal wire) that can couple an electrically generated magnetic field to another nearby conductor and induce a voltage and current in the second conductor. In at least one embodiment, the magnetic field can be generated by a current flowing in a first conductor according to Faraday's law of induction. The conductor has the property of inductance that is a function of the magnitude of the current flowing through the conductor and the shape or geometry of the conductor. Any conductor can be made into an inductance, but some shapes result in a stronger inductance than others. In at least one embodiment, a straight wire can have a small inductance that depends on its diameter and length. In at least one embodiment, the straight wire can be wound into a coil, for example, by the additive combination of the magnetic fields between each turn, multiplying the inductance by the number of turns per unit length and strengthening the overall magnetic field. In at least one embodiment, the magnetic fields from each turn combine, resulting in a doubling of the magnetic field generated by the straight wire according to Ampere's law. In at least one embodiment, the coil can be a planar coil, a solenoid, or a helical coil such as a tapered helix.

[0029] Here, "capacitor" generally can refer to a passive electrical device that stores charge and electrical energy in the form of an electric field. In at least one embodiment, a capacitor generally has at least two conductive plates that are separated by a dielectric material and are in proximity to each other. In at least one embodiment, the dielectric material can be air (or another gas) or a vacuum. In at least one embodiment, the dielectric material can generally be a solid or liquid material such as a polymer, ceramic, or semi-liquid electrolyte. In at least one embodiment, opposite charges can accumulate on adjacent plates, potentially forming an electric field that spreads from plate to plate through the dielectric material. In at least one embodiment, the electric field can store electrical energy.

[0030] Here, "capacitance" generally can refer to the ratio of the amount of charge in coulombs stored on the plates of a capacitor to a specific voltage applied to the plates. In at least one embodiment, capacitance can refer to the capacitive behavior of a metallic structure that is not necessarily intended to be used as an individual capacitor electrical device.

[0031] Here, "inductance" generally can refer to both an electrical circuit element and the physical properties of that element. In at least one embodiment, any conductor that includes a short straight wire has inductive properties. In at least one embodiment, inductance is the ratio of the magnetic flux generated by a current flowing through a conductor. In at least one embodiment, when a current flows through a conductor, a magnetic field is also associated with the inductance. In at least one embodiment, the value of the inductance of a conductor (e.g., self - inductance) also determines the magnitude of the voltage induced in the conductor by a changing magnetic flux passing through the conductor. In at least one embodiment, the value of the inductance is a function of the geometric shape of the conductor, such as the cross - sectional shape and dimensions of the conductor, the number and dimensions of the turns of a solenoid or spiral conductor, and the permeability of the medium surrounding the coiled conductor. Here, "inductance" generally may refer to a distributed inductance rather than necessarily an individual inductor. In at least one embodiment, an individual inductor is typically a coil as a lumped circuit element. In at least one embodiment, "inductance" can refer to the distributed inductance along an ICP antenna as defined below. In at least one embodiment, inductance can refer to a part or segment of an ICP antenna, and a part of the ICP antenna is a distributed inductance rather than an individual inductor.

[0032] Here, "plasma" generally can refer to a gaseous formation that includes charged particles such as positively or negatively charged atomic or molecular ions and electrons. In at least one embodiment, plasma is considered the fourth state of matter.

[0033] Here, the "inductively coupled plasma" (ICP) generally refers to a plasma generated by a time-varying magnetic field emitted from a primary inductance or plasma antenna, generally in the form of a coil, that conducts a radio frequency (RF) current. In at least one embodiment, a low concentration of ionized atoms or molecules and free electrons in the gas can be generated by a discharge. In at least one embodiment, a slightly ionized gas may be regarded as a secondary inductance coupled to the plasma antenna, which may be regarded as the primary inductance of a transformer, and the plasma may be regarded as the secondary inductance of a transformer to which the primary side is coupled. In at least one embodiment, the gas can pass through an electromagnetic field generated by an adjacent ICP antenna, where the charges are accelerated by a time-varying electric field associated with the time-varying magnetic field (in accordance with Faraday's law of induction and the Faraday-Maxwell equations). In at least one embodiment, the accelerated electrons can collide with neutral atoms or molecules to generate more ions and secondary electrons, increasing the plasma density of the charged particles. In at least one embodiment, the acceleration of the particles, and thus the magnitude of the collision velocity, is proportional to the strength of the electric field, and the strength of the electric field is proportional to the strength of the magnetic field. In at least one embodiment, the strength of the magnetic field is proportional to the magnitude of the current flowing through the ICP antenna.

[0034] Here, the "ICP antenna" generally refers to an inductance through which an RF current passes and can radiate RF power within a limited range as a near-field static electromagnetic field and a propagating electromagnetic field. In at least one embodiment, an RF current flows through the ICP antenna, generating an electromagnetic field that couples to a partially ionized gas or a fully developed plasma. In at least one embodiment, the partially ionized gas may have the potential to develop into a plasma under the action of the electromagnetic field.

[0035] Here, the "tuned portion" generally may refer to a part of the ICP antenna that is coupled to a parallel capacitor and forms a tank circuit, for example, a coil segment. In at least one embodiment, due to the inductance of the coil segment and the capacitance of the parallel capacitor, the tank circuit is tuned to a resonance frequency defined by 1 / [2π√LC], where L is the inductance and C is the capacitance.

[0036] Here, the "untuned portion" generally may refer to a part of the ICP antenna that is not coupled to a capacitor to set the resonance frequency, for example, a coil segment. Thus, the untuned portion may not resonate at a specific frequency other than the self-resonance frequency that can be determined by parasitic capacitance. In at least one embodiment, the parasitic capacitance is the capacitance between the windings of the coil segment. In at least one embodiment, the parasitic capacitance also includes capacitance to nearby conductors. In at least one embodiment, the self-resonance frequency can also be determined by the inherent inductance of the coil segment. In at least one embodiment, the self-resonance frequency can be above or below the resonance frequency of the tuned portion.

[0037] Here, the "tank circuit" generally may refer to a parallel combination of an inductance and a capacitor. In at least one embodiment, the tank circuit has a characteristic resonance frequency f 0 determined by the values of the inductance L and the capacitance C, and f 0= 1 / [2π√LC]. In at least one embodiment, the tank circuit has a resonance curve that is a plot of the circuit impedance as a function of frequency. In at least one embodiment, the curve is non-monotonic in that it has a peak at the resonance frequency. In at least one embodiment, the sharpness and bandwidth of the resonance curve are determined by the quality factor Q of the circuit. Here, "Q" can be defined as the ratio of the energy stored in the electric and magnetic fields of the capacitor and inductor, respectively, to the energy dissipated as heat by the resistive part of the circuit. In at least one embodiment, since the resistance can include a long, thin wire wound around the coil, most of it can be inductance (e.g., copper loss, skin effect, etc.). In at least one embodiment, the smaller the resistance of the coil, the larger the Q. In at least one embodiment, Q can be lowered by inserting an individual resistor in series with the inductance within the tank circuit. In at least one embodiment, the resonance curve can be broadened by a low circuit Q (e.g., Q < 10) and sharpened by a high circuit Q (e.g., Q > 10). In at least one embodiment, the tank circuit exhibits a very large circulating current at or near resonance. In at least one embodiment, the circulating current can be the product of the line current or feed current multiplied by Q. In at least one embodiment, due to the large circulating current, very large voltages can also occur across the capacitor and inductor. In at least one embodiment, at the same time, the impedance of the tank circuit increases dramatically at or near resonance, and at f 0 it becomes purely resistive. In at least one embodiment, the resonant tank circuit can have a very high effective resistance that significantly reduces the conduction of RF current at f 0 . Here, the "tank circuit" derives from the ability of a circuit to store electrical energy. The tank circuit is a frequency-determining component of oscillator circuits and tuned coupling circuits as found in tuned RF amplifier stages.

[0038] Here, the "dielectric material" can generally refer to non-conductive materials such as polymers, ceramics, glass, wood, etc.

[0039] Here, "high frequency" generally refers to electromagnetic radiation that oscillates at a frequency within a spectrum that substantially includes frequencies from 10 kilohertz (kHz) to 1 terahertz (THz, or 10 15 Hz). In at least one embodiment, the upper limit of the high-frequency spectrum can extend up to several hundred gigahertz (GHz). The term "high frequency" is usually abbreviated as "RF".

[0040] Here, "RF signal source" generally refers to an electronic device that can generate an electrical signal at high frequency. In at least one embodiment, the RF signal source is capable of outputting a large RF current (e.g., 1 ampere rms or more) at a significant voltage. In at least one embodiment, the RF signal source for an ICP antenna can generally output up to several hundred volts and up to several hundred amperes, generating a significant amount of power.

[0041] Here, "process tool" generally refers to equipment used in semiconductor manufacturing, and is also called a "semiconductor process tool" for semiconductor processing. In at least one embodiment, the process tool can generally include a vacuum chamber in which processes such as substrate plasma etching or plasma-enhanced material deposition are performed. In at least one embodiment, other non-plasma-related processes can also be performed by the process tool.

[0042] Here, "chuck" generally refers to a stage or platform on which a substrate (e.g., a wafer) can be mounted.

[0043] Here, the "substrate" generally can refer to a wafer comprising a semiconductor (e.g., silicon) or an insulator (e.g., aluminum nitride, silicon carbide, silicon nitride, aluminum oxide, float glass, borosilicate glass, etc.). The wafer may be a slice of single crystal semiconductor or insulator. In at least one embodiment, the wafer can also include a polycrystalline material or an amorphous (glass-like) material. In at least one embodiment, the wafer can generally have a diameter in the range of 100 mm to 500 mm and a thickness in the range of generally 100 microns to 1 mm.

[0044] Here, the "process chamber" generally can refer to the vacuum chamber of a process tool into which a substrate can be introduced for processing. In at least one embodiment, the process chamber may include a chuck for holding the substrate. In at least one embodiment, the process chamber may be a plasma etching chamber.

[0045] Here, the "utility chamber" generally can refer to a chamber or enclosure on a process tool in which electronic equipment or other sensitive equipment can be housed and isolated from the process chamber. In at least one embodiment, the ICP antenna can be housed in a utility chamber isolated from the generally harsh environment of the process chamber. In at least one embodiment, the utility chamber can be maintained under vacuum or at atmospheric pressure.

[0046] Here, "spatial control" generally can refer to the position control of a process. For example, spatial control of plasma etching or deposition by providing spatial decoupling of the ICP antenna to the plasma.

[0047] Here, "coupled" generally can refer to directly attaching one electronic component to another electronic component. In at least one embodiment, an electric field or a magnetic field can couple one component to another, the field is controlled by one component, and affects another component in some way.

[0048] Here, the "magnetic field" generally can refer to the lines of the direction and intensity of magnetic flux emitted from a magnetized material or an energized material.

[0049] Here, the "plasma-enhanced process" generally can refer to, for example, a semiconductor process in which plasma is used to assist the process in some way. In at least one embodiment, the plasma-enhanced process is enhanced compared to a similar or same process that does not use plasma. In at least one embodiment, reactive ion etching and plasma-enhanced chemical vapor deposition or plasma-enhanced atomic layer deposition are examples of plasma-enhanced processes.

[0050] Here, the "reactive species" generally can refer to ions or neutral radicals formed in the plasma.

[0051] Here, the "ion" generally can refer to a charged atom or molecule. In the context of the present disclosure, an ion can be a gaseous atom or molecule that loses or gains electrons in the plasma.

[0052] FIG. 1 shows a cross-sectional view of a plasma processing tool 100a including a chuck 102 within a process chamber 104 according to at least one embodiment. In at least one embodiment, a radio frequency (RF) signal source 106 is coupled to an inductively coupled plasma (ICP) antenna 108. In at least one embodiment, the ICP antenna 108 is shown as a planar spiral coil (e.g., a "pancake coil"). Individual windings of the flat spiral coil are shown in cross-section. In at least one embodiment, a wafer 103 can be supported on the chuck 102. In at least one embodiment, the wafer 103 can undergo a plasma-enhanced deposition or etching process.

[0053] In at least one embodiment, the ICP antenna 108 may be located outside the process chamber 104. In at least one embodiment, the ICP antenna 108 can be wound around the process chamber 104, whereby the ICP antenna 108 has a helical (e.g., solenoid-like) geometry. A solenoid may generally have a cylindrical form factor, and the conductor may be in the form of a helical coil. In at least one embodiment, as shown, a maximum coupling to the plasma 114 can be achieved by the planar geometry of the ICP antenna 108 as compared to a solenoid or helical shape.

[0054] In at least one embodiment, the ICP antenna 108 may be positioned within the upper chamber 110 in very close proximity to the dielectric window 112. In at least one embodiment, the dielectric window 112 separates the upper chamber 110 from the process chamber 104. In at least one embodiment, the ICP antenna 108 may be enclosed within the upper chamber 110 so as to be isolated from an inductively coupled plasma such as the plasma 114 that may be generated by the ICP antenna 108. In at least one embodiment, the dielectric window 112 may include a dielectric material that is transparent to electromagnetic fields to allow passage of the electromagnetic field from the antenna 108 to the process chamber 110.

[0055] In at least one embodiment, the ICP antenna 108 may generally have a geometry that follows the shape of the dielectric window 112. In at least one embodiment, the ICP antenna 108 may be directly above the dielectric window 112 and closest to the process chamber 104 such that the magnetic field spreads maximally into the process chamber 104 and reaches the wafer 103. In at least one embodiment, the ICP antenna 108 is planar following the planar geometry of the dielectric window 112.

[0056] In at least one embodiment, during operation, plasma 114 is formed over wafer 103. In at least one embodiment, plasma 114 can be formed by inductive coupling of an electromagnetic field emitted from ICP antenna 108 and interacting with a low-pressure gas flowing into process chamber 104. In at least one embodiment, the low-pressure gas can include a deposition precursor, an etching gas, and an inert or reactive carrier gas. In at least one embodiment, the time-varying magnetic field penetrating into process chamber 104 can oscillate at the same frequency as the RF current flowing through ICP antenna 108. In at least one embodiment, the magnetic field may spread into process chamber 104 through dielectric window 112.

[0057] In at least one embodiment, the RF current flowing through ICP antenna 108 can have a magnitude of several tens of amperes to several hundreds of amperes. In at least one embodiment, the coiled structure of ICP antenna 108 can generate a large amount of magnetic flux to inject a large amount of electromagnetic power into process chamber 104, and can ignite and maintain plasma 114. In at least one embodiment, the electromagnetic power coupled to plasma 114 generates gaseous ions within plasma 114. In at least one embodiment, the ion density can be increased and decreased by controlling the power injected into ICP antenna 108. In at least one embodiment, an increase in the ion density can enable an increase in the deposition rate or the etching rate.

[0058] In at least one embodiment, the ICP antenna 108 can comprise a hollow copper tube wound in a flat coil to carry cooling water or other fluid, as a large RF current flowing within the tube wall can generate a large amount of heat. In at least one embodiment, due to the skin effect for the RF current flowing within the conductor, the RF current may generally flow on the surface of the pipe. In at least one embodiment, the RF current can cross a very small cross-section penetrating from the surface of the conductor to the internal region by several microns or dozens of microns or hundreds of microns, and the skin depth is inversely proportional to the square root of the applied RF frequency. In at least one embodiment, due to the small cross-section for the current, a substantial AC (alternating current) resistance may occur within the ICP antenna 108. In at least one embodiment, a large-diameter pipe can be used to increase the RF cross-section. In at least one embodiment, the ICP antenna 108 comprises a plurality of windings 116 shown in cross-section. In at least one embodiment, the ICP antenna 108 can be coupled to the RF signal source 106 at the inner terminal 118 and the outer terminal 120.

[0059] FIG. 2A shows an electrical circuit diagram of an RF circuit 200a comprising a spatially tunable inductively coupled plasma (ICP) antenna 202 coupled to an RF signal source 204, according to at least one embodiment. In at least one embodiment, the ICP antenna 202 comprises a plurality of serially coupled inductances 206, 208, 210, 212, 214, and 216. In at least one embodiment, the inductive segments 206-216 are also labeled L1, L2, L3, L4, L5, L6, respectively. The labels L1-L6 may be regarded as the inductance values for the respective inductances 206-216. In at least one embodiment, the inductances 206-216 may be individual discrete inductances such as individual coils connected in series. In at least one embodiment, the inductances 206-216 may be a series of distributed inductances as continuous segments of a single coil, and each coil segment has an inductance L nhaving n = 1, 2, 3, 4, 5, 6, etc. In at least one embodiment, the inductance L n can be a function of geometric parameters such as the number of turns, the spacing between turns, the diameter of the turns, the width of the turns, and the mutual inductance with adjacent inductances.

[0060] In at least one embodiment, shunt capacitors 218, 220, and 222 (labeled C1, C2, and C3, respectively) are coupled in parallel with inductances L1, L3, and L5 (e.g., inductances 206, 210, and 214), and the parallel combination of the inductance (or segment) and the shunt capacitor forms an LC tank circuit. In at least one embodiment, the tank circuit may be a tuning portion of the ICP antenna 202. In at least one embodiment, shunt capacitors 218, 220, and 222 may be fixed capacitors or variable capacitors. In at least one embodiment, the variable capacitor may be of any suitable type, such as a voltage-controlled capacitor (e.g., varactor diode), or an electronically or mechanically switchable capacitor bank, or a mechanically tunable plate capacitor such as a butterfly capacitor. In at least one embodiment, any suitable type of variable capacitor can be considered. In at least one embodiment, the fixed capacitor may also be a high-voltage, high-power type such as a doorknob capacitor.

[0061] In at least one embodiment, a plurality of tank circuits such as tank circuits 224, 226, and 228 may be included in the ICP antenna 202. In at least one embodiment, the tank circuits may be adjacent to each other or separated by a detuned portion of the ICP antenna 202. In at least one embodiment, the detuned portion is a coil segment not coupled to a shunt capacitor.

[0062] In at least one embodiment, the tank circuits 224-228 resonate at an RF frequency determined by the values of the inductance and shunt capacitance. In at least one embodiment, the bandwidth of the individual tuning tank circuits 224-228 can be determined by the quality factor Q of the circuit. Q can generally be defined as the ratio between the power stored in the electric and magnetic fields of the capacitor and inductance, respectively, and the power dissipated as heat due to the resistive losses of the tank circuit and the plasma. In at least one embodiment, the tank circuit may derive its name from its ability to store large amounts of electrical energy. In at least one embodiment, a large Q factor (e.g., Q > 20) generally corresponds to a highly tuned circuit with a narrow bandwidth and sharp resonance, while a lower Q factor (e.g., Q < 10) generally corresponds to a larger bandwidth and less sharp resonance. In at least one embodiment, most of the resistive losses in the tuning tank circuit are due to the series resistance of the inductance or the plasma.

[0063] Parallel resonant circuits also generate high impedance at or near resonance. At resonance of a high-Q tank circuit, the impedance can be in the range of tens of ohms to hundreds of thousands of ohms, and can effectively form an open circuit to RF at the resonance frequency or a frequency close to the resonance frequency. In addition to the high impedance of the resonant tank circuit, a large amount of stored electrical energy may appear as a very large circulating current flowing in the tank circuit. A large circulating current is generated by the continuous supply of line current to the tank circuit and the accumulation of energy stored in the electric and magnetic fields of the capacitor and inductor components. The circulating current can be the product of Q and the line current, and the line current is the current supplied to the tank circuit. For a line current of several amperes, the circulating current in the tank circuit can be hundreds of amperes depending on the Q value of the circuit and the supplied RF current. Due to the very large circulating current, the inductance in the tank circuit or in the adjacent plasma may be significantly heated. In at least one embodiment, a very large voltage (e.g., thousands of volts) exists between the capacitor and the inductor, which may cause an arc discharge. The components in the tank circuit are designed to withstand very large currents and voltages, increasing the overall cost.

[0064] In at least one embodiment, the frequency of the RF current output from the RF signal source 204 can be adjusted to be near the resonant frequency of a particular tuning tank circuit. In at least one embodiment, the RF current can be tuned to the resonant frequency of any of the tank circuits 224, 226, and 228. In at least one embodiment, the individual tank circuits can have different resonant frequencies, or two or more tank circuits can be tuned to the same resonant frequency or can have near resonant frequencies. In at least one embodiment, the large circulating current in one or more resonant tank circuits generates a large magnetic field that can couple to a plasma such as the plasma 114 shown in FIG. 1. In at least one embodiment, a large amount of power from the individual rank circuits can be coupled to the plasma. In at least one embodiment, the individual tank circuits can have different physical locations on the ICP antenna 202, allowing for a spatially distinct coupling of the local magnetic field to the plasma.

[0065] In at least one embodiment, the ICP antenna 202 can be designed to apply high power to a first portion of the plasma generated within a processing chamber such as the process chamber 104 shown in FIG. 1, and low power can be applied to a second portion of the plasma. In at least one embodiment, within the high power region, the plasma can have a higher plasma density. In at least one embodiment, as the ion density within the region of the plasma increases, for example, the etching rate or deposition rate across a desired portion of the substrate being etched can increase. In at least one embodiment, the spatial differentiation of the ICP power application to the plasma can enable the design of the ICP antenna 202 to adjust the plasma to have a higher plasma density, for example, across a desired portion of the substrate. In at least one embodiment, the ICP antenna may be designed according to process criteria.

[0066] In at least one embodiment, inductances 208, 212, and 216 are not coupled to a capacitor and can simply couple adjacent tuned tank circuits. In at least one embodiment, inductances 208, 212, and 216 are untuned segments of a single coil between tuned segments (e.g., tank circuits). In at least one embodiment, by providing an untuned segment or portion of the ICP antenna 202, adjacent tuned tank circuits 224, 226, and 228 can be advantageously decoupled.

[0067] In at least one embodiment, the ICP antenna 202 is optionally serially coupled to an external series capacitor 230. In at least one embodiment, the series capacitor (or capacitance) 230 can serve to provide a means for reducing the input impedance of the ICP antenna 202. In at least one embodiment, the input impedance of the ICP antenna 202 can include a mostly inductive reactance that is proportional to the total inductance of the ICP antenna 202. In at least one embodiment, the series capacitor 230 can serve to reduce the overall inductive reactance of the ICP antenna 202 by providing a capacitive reactance. Capacitive reactance is inversely proportional to the value of capacitance and frequency and has a sign opposite to that of inductive reactance. Thus, the two reactances combined in series oppose each other and can be subtracted from each other. In at least one embodiment, multiple series capacitors can be used in the circuit and can also be distributed between series inductances.

[0068] In at least one embodiment, due to the reduction of the input impedance of the ICP antenna 202, the output voltage from the RF signal source 204 may decrease in order to generate the same output current for a given power output. In at least one embodiment, an impedance matching network (not shown) may be required to match the output impedance of the RF signal source 204 with the input impedance of the ICP antenna 202 to maximize power transmission. In at least one embodiment, the output impedance of the RF signal source 204 can be 50 ohms (e.g., mostly resistive), while the input impedance of the ICP antenna 202 is mostly reactive and can be in the tens to hundreds of ohms. In at least one embodiment, a matching network (not shown) can be inserted between the RF signal source 204 and the ICP antenna 202 to match the impedance for maximum power transmission. The decrease in the antenna input impedance corresponds to a decrease in the output voltage from the antenna side of the matching network, which may reduce the possibility of, for example, arc discharge and reduce the cost associated with the matching circuit components.

[0069] Figure 2B shows an electrical circuit diagram of an alternative ICP antenna circuit 200b comprising an ICP antenna 252 coupled to an RF signal source 254, according to at least one embodiment. In at least one embodiment, the spatially tunable ICP antenna 252 comprises inductances 256, 258, 260, 262, and 264 coupled in series. In at least one embodiment, the inductances 256 - 264 may be a plurality of individual inductances, or a single inductance or multiple segments of the inductive portion of the ICP antenna 252. In at least one embodiment, a series capacitor 266 may be coupled to the terminals of the ICP antenna 252. In at least one embodiment, the series capacitor 266 can be adjusted to control the antenna impedance. In at least one embodiment, a parallel capacitor 268 is coupled across a pair of inductances including inductances 256 and 258. Although the schematic shows inductances 256 and 258 as adjacent, according to at least one embodiment, they may be separated by a non-inductive component such as a wire or capacitor.

[0070] In at least one embodiment, the inductances 256 - 260 can also be separated from the inductances 262 and 264 by a distance sufficient to reduce the magnetic coupling and mutual inductance to a sufficiently low value. Mutual inductance can be defined as the combined effect of magnetic fields from one inductance to another. In at least one embodiment, the magnetic field vectors from each magnetic field can add or subtract from the effective inductance of both coupled inductances, increasing or decreasing them respectively. Mutual inductance also depends on the degree of coupling between two adjacent inductances. For example, the coupling coefficient decreases as the distance increases. In at least one embodiment, physically separating adjacent inductances reduces the degree of coupling, and thus the mutual inductance.

[0071] In at least one embodiment, mutual inductance can also be sufficiently reduced to zero or nearly zero by a magnetic shield or orthogonal arrangement. In at least one embodiment, it may be desirable to reduce the mutual inductance to a small value. In addition to the physical separation as described, in at least one embodiment, the mutual inductance can also be reduced by a magnetic shield or orthogonality. In at least one embodiment, a magnetic shield or orthogonality can be used to bring two or more inductances into proximity, but it is possible to orient them such that their magnetic field vectors are orthogonal to each other. Magnetic coupling can, according to at least one embodiment, be reduced to nearly zero in such a configuration. In at least one embodiment, the magnetic shield can be achieved by placing the inductance within a non-ferromagnetic metal can or by using a ferromagnetic can or wall, and the ferromagnetic material can be conductive or non-conductive, such as MgZn or NiZn ferrite, or a magnet.

[0072] In at least one embodiment, capacitor 268 can be shunted (e.g., coupled in parallel) across inductances 256 and 258 to form parallel tank circuit 270. In at least one embodiment, tank circuit 270 can be spatially located along ICP antenna 252 to coincide with a spatial location above a chuck (e.g., chuck 102) within a process chamber (e.g., process chamber 104, FIG. 1) below ICP antenna 252. In at least one embodiment, capacitor 268 is a fixed capacitor. In at least one embodiment, capacitor 268 is a variable capacitor.

[0073] In at least one embodiment, the resonant frequency of the tank circuit can be expressed by 1 / [2π√LC], where L is the inductance of the tank circuit and C is the capacitance of the tank circuit. In at least one embodiment, a plurality of inductances included in the tank circuit can be combined to achieve a specific resonant frequency with a given parallel capacitor. In at least one embodiment, capacitor 268 can be shunted across one or more inductances, such as inductances 262 and 264, to cover a desired spatial region of the plasma chamber or to achieve a lower resonant frequency than may be possible with a single inductance. In at least one embodiment, a tank circuit, such as tank circuit 270, can be selected by its spatial position along ICP antenna 252. At least one embodiment shows capacitor 268 shunted across inductances 256 and 258, but capacitor 268 may be shunted across any other group of inductances, such as a pair of inductances 262 and 264. Inductances 262 and 264 may be adjacent to each other and located at different spatial positions along ICP antenna 252.

[0074] During operation, in at least one embodiment, the RF signal source 254 is tuned to the resonant frequency of the tank circuit 270 or a frequency in the vicinity thereof, and can strongly resonate the tank circuit 270. In at least one embodiment, the large circulating current resulting within the tank circuit 270 may generate a strong magnetic field that may be substantially localized at the antenna position along the ICP antenna 252. In at least one embodiment, the magnetic field emitted from the untuned portion of the ICP antenna 252 in the absence of the tank circuit may be significantly weaker compared to the magnetic field generated by the tank circuit 270. In at least one embodiment, during operation, a strong magnetic field may couple to a specific spatial region of the plasma and generate a spatially local high ion density within the plasma region, which may be spatially correlated with the coordinates on the substrate when the substrate is clamped so as to be chucked within the process chamber. In at least one embodiment, when an etching or deposition process is in progress, the etching or deposition rate at a spatial location on the substrate may be improved compared to the neighboring regions.

[0075] In at least one embodiment, capacitor 268 may be a variable capacitor and the source frequency is fixed. In at least one embodiment, as a variable capacitor, the capacitance of capacitor 268 may be adjusted or tuned to bring tank circuit 270 into resonance or near resonance at a fixed applied frequency of the RF voltage output by RF signal source 254. In at least one embodiment, the tank circuit may be tuned, for example, to be within 50% to 90% of the applied frequency (e.g., on both sides of the resonance curve). Within this range, in at least one embodiment, a strong circulating current may be generated. In at least one embodiment, depending on the circuit Q, the resonance curve of tank circuit 270 may rise sharply when the resonance frequency of the tank circuit is tuned within 5% of the applied frequency. For resonance frequencies within 2% of the applied frequency, the circuit response may be unpredictable and may appear as difficult and unpredictable spatial control of the plasma coupled to ICP antenna 252. Additionally, due to the extremely high parallel impedance, the line current can be effectively blocked from reaching other parts of ICP antenna 252. In at least one embodiment, the applied frequency or resonance frequency of tank circuit 270 may be continuously adjustable to a value that allows a relatively small enhancement of spatially local magnetic coupling compared to the untuned portion of ICP antenna 252.

[0076] According to at least one embodiment, if capacitor 268 has a fixed capacitance, the above description may be reversed. In at least one embodiment, the resonance frequency of tank circuit 270 is also fixed by using capacitor 268 having a fixed capacitance. In at least one embodiment, the applied frequency of the RF current output from RF signal source 254 may be tuned near the resonance frequency of tank circuit 270.

[0077] Figure 2C shows an electrical circuit diagram of a further alternative ICP antenna circuit 200c in at least one embodiment. In at least one embodiment, a spatially tunable ICP antenna 272 comprises inductances 276, 278, 280, 282, and 284 in series. In at least one embodiment, the ICP antenna 272 also comprises a tank circuit 290 and a tank circuit 292 representing a plurality of tuning circuits spatially distributed along the ICP antenna 272. In at least one embodiment, the tank circuit 290 comprises a capacitor 286 coupled in parallel to inductances 276 and 278 representing a plurality of inductances. In at least one embodiment, the inductance 276 can be directly adjacent to the inductance 278, and the two inductances can be strongly coupled or physically separated for weak coupling. In at least one embodiment, the inductances 276 and 278 can also be spatially close but magnetically shielded or orthogonal as described above. In at least one embodiment, the combination of the inductances 276 and 278 can be selected to provide a larger inductance in parallel with the capacitor 286 than can be achieved with only one inductance. In at least one embodiment, a lower resonant frequency of the tank circuit 290 can be achieved.

[0078] Similarly, in at least one embodiment, the tank circuit 292 comprises a capacitor 288 in parallel with inductances 282 and 284. In at least one embodiment, the tank circuit 292 can be described in a manner similar to the above-described tank circuit 290. In at least one embodiment, the tank circuit 292 can be located at a different spatial position from the tank circuit 290 having the untuned portion of the ICP antenna 272 comprising the inductance 280 between the two tank circuits. In at least one embodiment, the tank circuit 292 may have a resonant frequency different from that of the tank circuit 290.

[0079] In at least one embodiment, the frequency responses of the tank circuits 290 and 292 can be controlled by tuning the RF signal source 274 or by adjusting the capacitors 286 and 288 (as variable capacitors). In at least one embodiment, depending on the desired adjustment or tuning speed, by tuning either the source frequency or the resonance of the tank circuits, or both, a large circulating current can be generated simultaneously in both tank circuits 290 and 292, resulting in a spatially local strong magnetic coupling to the plasma coupled to the ICP antenna 272.

[0080] In at least one embodiment, the resonant frequencies of the tank circuits 290 and 292 may be different, with the first tank circuit resonating at a first frequency and the second tank circuit resonating at a second frequency. In at least one embodiment, the applied frequency can be tuned such that the first tank circuit resonates strongly, and the second tank circuit can exhibit a weak resonance. In at least one embodiment, the magnetic coupling from the tank circuit 290 can be strong with respect to the plasma coupled to the ICP antenna 272, while the magnetic coupling from the tank circuit 292 may be weaker but still stronger than the coupling from the untuned portion. In at least one embodiment, resonance can enable spatial control of the plasma density. In at least one embodiment, the plasma density can be significantly proportional to, for example, the plasma etching rate or the plasma enhanced deposition rate.

[0081] FIG. 3A shows a physical embodiment of the circuit described in FIGS. 2A-2C according to at least one embodiment. FIG. 3A shows an isometric view of a spatially tunable ICP antenna 300a comprising a coil 302 having an inductance LT. In at least one embodiment, coil 302 is shown as a planar spiral coil with an inner terminal 304 and an outer terminal 306. Inner terminal 304 is substantially at the center of coil 302, although in at least one embodiment, inner terminal 304 can be at a non-zero radial distance from the center of coil 302. Coil segment 310 is shown as a spiral coil segment, although in at least one embodiment, coil segment 310 can comprise a short conductor for directly connecting coil segment 308 to coil segment 312.

[0082] For example, coil segment 310 may comprise a straight segment of wire or a portion of a coil conductor to bridge the gap between coil segments 308 and 312. In at least one embodiment, coil segment 310 may comprise a solid annular sheet of conductor spanning the gap between coil segments 308 and 312. In at least one embodiment, coil segment 310 comprises a continuous winding 314 between the windings of coil segments 308 and 312. In at least one embodiment, there are a plurality of coil segments 308, 310, and 312 electrically coupled in series between inner terminal 304 and outer terminal 306.

[0083] In at least one embodiment, coil segments 308, 310, and 312 may be substantially concentric, and coil segment 308 is the outermost coil segment at the periphery of coil 302. In at least one embodiment, coil segment 310 may be the middle coil segment of coil 302, and coil segment 312 may be the innermost coil segment of coil 302. Here, the individual coil segments 308, 310, and 312 are shown with different gray shades to make them distinguishable. In at least one embodiment, the individual coil segments comprise a plurality of windings 314, enabling coil segments 308, 310, and 312 to exhibit inductances L1, L2, and L3, respectively. The sum of the inductances L1, L2, and L3 may be substantially equal to L T and may be substantially equal to.

[0084] In at least one embodiment, the inductance L of a planar coil can be expressed as L(μH) = kN 2 A 2 / (30A - 11Di), where k is a proportionality coefficient, N is the number of windings, Di is the inner diameter of the coil, A = [Di + N(W + S)] / 2, W is the width of the winding, and S is the distance between windings. Here, the dimensions are in inches, and the inductance L is expressed in microhenries (μH).

[0085] In at least one embodiment, coil segment 308 includes winding 314 between outer terminal 306 at radius R1 and first interconnect terminal 316 at radius R2 at the periphery of coil 302. In at least one embodiment, coil segment 310 can occupy the middle portion of coil 302. In at least one embodiment, coil segment 310 includes winding 318 between second interconnect terminal 320 at radius R2 and third interconnect terminal 322 at radius R2. In at least one embodiment, second interconnect terminal 320 may abut first interconnect terminal 316 at radius R2. In at least one embodiment, coil segment 312 includes winding 324 between fourth interconnect terminal 326 at radius R3 and inner terminal 304. In at least one embodiment, fourth interconnect terminal 326 may abut third interconnect terminal 322. Inner terminal 304 can be substantially at the center of coil 302, but in at least one embodiment, inner terminal 304 can be located at a substantially radial distance from the center of coil 302.

[0086] In at least one embodiment, ICP antenna 300a further includes capacitors 328 and 330 coupled in parallel to coil segments 308 and 312, respectively. In at least one embodiment, capacitors 328 and 330 are schematically represented by capacitor symbols, indicating that capacitors 328 and 330 can be any type of suitable fixed or variable capacitor. In some embodiments, capacitors 328 and 330 may have different or substantially the same fixed capacitance. In at least one embodiment, one or both of capacitors 328 and 330 may be variable capacitors having independently tunable capacitance.

[0087] Two of the three coil segments 308 and 312 are each coupled in parallel to capacitors 328 and 330, although in at least one embodiment, any of coil segments 308, 310, and 312 can be coupled in parallel to either one of capacitors 328 or 330. In at least one embodiment, the parallel combination of coil segment 308 and capacitor 328 comprises a first tank circuit 332. In at least one embodiment, the parallel combination of coil segment 312 and capacitor 330 comprises a second tank circuit 334.

[0088] In at least one embodiment, capacitors 328 and 330 may be physically offset from the plane of coil 302 and may be above or below the plane of coil 302. Here, the plane of the coil is within the x-y plane of the figure. The Z-axis passes above and below coil 302. Here, "above" and "below" can be relative terms with respect to the orientation of coil 302. For example, in a semiconductor processing tool, coil 302 can be oriented in a substantially horizontal configuration relative to vertical. In other orientations, "below" can generally refer to the side of the coil facing the plasma coupled to the coil. Here, "above" can generally refer to the side of the coil facing away from the plasma.

[0089] In at least one embodiment, capacitor 328 can be coupled to coil segment 308 at outer terminal 306 and first interconnect terminal 316 by leads 336 and 338. In at least one embodiment, leads 336 and 338 may have an offset h 1 from the plane of coil 302. In at least one embodiment, capacitor 330 can be coupled to coil segment 312 by leads 340 and 342 attached to interconnect terminal 326 and inner terminal 304 of coil 302. In at least one embodiment, leads 340 and 342 may have an offset h 2 from the plane of coil 302. In at least one embodiment, the offset h 1 and h 2may be substantially equal.

[0090] In at least one embodiment, the RF signal source 344 can be coupled to the ICP antenna 300a at the outer terminal 306 of radius R1 and directly coupled to the coil segment 308 located at the periphery of the ICP antenna 300a. In at least one embodiment, the RF line current can flow from the RF signal source 344 into the tank circuit 332. In at least one embodiment, the tank circuit 332 may be the first tuning portion of the ICP antenna 300a operable to resonate at a first frequency. In at least one embodiment, the RF current can then continue to flow through the coil segment 310 joined to the coil segment 308 by abutting the first and second interconnect terminals 316 and 320 of radius R2. In at least one embodiment, the coil segment 310 is not coupled to a parallel capacitor and is thus not part of the tank circuit. Apart from the self-resonance that may be inherent to the coil segment 310, the coil segment 310 may be the untuned portion of the ICP antenna 300a.

[0091] In at least one embodiment, the RF current can continue to flow into the coil segment 312 through the abutted third and fourth interconnect terminals 322 and 326 of radius R3. In at least one embodiment, the coil segment 312 is part of a tank circuit 334 that includes a capacitor 330 coupled in parallel to the coil segment 312. In at least one embodiment, the coil segment 312 may be a second tuning portion of the ICP antenna 300a operable to resonate at a second RF frequency. In at least one embodiment, the RF current can exit the coil 302 at the inner terminal 304 and return to the RF signal source 344. In at least one embodiment, a series capacitor 346 can be inserted between the terminal 304 and the RF signal source 344 to provide a capacitive reactance that counteracts the inductive reactance of the ICP antenna 300a. In at least one embodiment, the reduction of the inductive reactance can also reduce the input impedance to the ICP antenna 300a, enabling a reduction in the drive voltage output from an impedance matching network (not shown) that can be inserted between the RF signal source 344 and / or between the RF signal source 344 and the terminal 306. In at least one embodiment, the capacitor 346 may be a fixed capacitor or a variable capacitor.

[0092] Figure 3B shows an isometric view of an alternative spatially tunable ICP antenna 300b with a coil 302 according to at least one embodiment. In at least one embodiment, coil segment 310 is coupled to a third capacitor 348. In at least one embodiment, coil segment 310 is intermediate between coil segment 308 at the periphery of coil 302 and coil segment 312, which is the innermost coil segment. In at least one embodiment, the parallel combination of coil segment 310 and capacitor 348 provides a third tank circuit 350 between tank circuit 332 and tank circuit 334. In at least one embodiment, since coil segment 310 is part of tank circuit 350, coil segment 310 may be regarded as the third tuning portion of ICP antenna 300b, coil segment 308 is the first tuning portion, and coil segment 312 is the second tuning portion.

[0093] In at least one embodiment, the first, second, and third tuning portions can be tuned to resonate at first, second, and third RF frequencies, respectively, and the first, second, and third resonant RF frequencies can be substantially different. In at least one embodiment, any two of the first, second, or third RF frequencies may be substantially the same. In at least one embodiment, the first, second, and third RF frequencies can be selected, as described above, to create regions of stronger and weaker spatial coupling to an inductively coupled plasma coupled to ICP antenna 300b, enabling spatial control of the ion density within the plasma.

[0094] In at least one embodiment, coil segment 310 can be adjacent to and thus magnetically coupled to coil segments 308 and 312. In at least one embodiment, the mutual inductance between coil segments can be advantageously used by increasing or decreasing the self - inductance of the individual coil segments 308, 310, and 312. In at least one embodiment, the magnetic coupling can be mitigated by inserting a magnetic shield between the coil segments, if desired. In at least one embodiment, the shield may comprise a thin foil or sheet of a ferromagnetic metal such as non - stainless steel and may be arranged orthogonal to the plane of coil 302 to prevent magnetic field lines arising from one coil segment from intersecting an adjacent coil segment.

[0095] FIG. 4A shows a cross - sectional view of a semiconductor processing tool 400 comprising a spatially tunable ICP antenna comprising a utility chamber 402 and a plasma chamber 404 above and adjacent to the utility chamber 402, according to at least one embodiment. In at least one embodiment, the plasma chamber 404 can be separated from the utility chamber 402 by a wall 406 comprising a dielectric material. Wall 406 may also be substantially transparent to RF electromagnetic fields and may thus sometimes be referred to as a dielectric window 406.

[0096] In at least one embodiment, the semiconductor processing tool 400 can include a spatially tunable ICP antenna 408 within the utility chamber 402. In at least one embodiment, the ICP antenna 408 can be, for example, any one of the ICP antennas 300a or 300b described above. In at least one embodiment, the ICP antenna 408 may include a planar spiral coil 410. In at least one embodiment, the coil 410 can be directly adjacent to the dielectric window 406 as shown. In at least one embodiment, the ICP antenna 408 may further include a shunt capacitor 412 coupled (e.g., shunted) in parallel with the coil segment 414 within the utility chamber 402. In at least one embodiment, the shunt capacitor 412 can be positioned on top of the coil 410. In at least one embodiment, during operation, the utility chamber 402 can be under vacuum or can hold an inert gas, a reactive gas, or air at atmospheric pressure and room temperature. In at least one embodiment, the utility chamber 402 can serve to isolate the ICP antenna 408 and associated electronic components from the plasma and harsh environment that may be present within the plasma chamber 404 during operation.

[0097] As described above, the shunt capacitor 412 can be coupled in parallel with the coil segment 414. In at least one embodiment, the coil segment 414 is at the periphery of the coil 410. In at least one embodiment, the capacitor 412 can be connected to the coil segment through leads 416 and 418. In at least one embodiment, the parallel combination of the shunt capacitor 412 and the coil segment 414 forms the tuned portion 420 of the ICP antenna 408. In at least one embodiment, the region of the coil 410 that extends between the inner terminal 422 of the coil 410 and the lead 418 is not shunted by the capacitor and constitutes the untuned portion 424 of the ICP antenna 408.

[0098] In at least one embodiment, the semiconductor processing tool 400 can further include an RF signal source 426. In at least one embodiment, the RF signal source 426 is coupled to the inner terminal 422 of the coil 410 (which is also the ICP antenna 408). In at least one embodiment, the RF signal source 426 can similarly be coupled to the outer terminal 428 of the coil 410. In at least one embodiment, a series capacitor 430 may optionally be included in the ICP antenna circuit as described above. In at least one embodiment, the series capacitor 430 is coupled to the outer terminal 428 of the coil 410 as shown and can return current to the RF signal source 426.

[0099] In at least one embodiment, during operation, the ICP antenna 408 can generate and maintain an inductively coupled plasma 432 (hereinafter, plasma 432) that is electromagnetically coupled to the ICP antenna 408. In at least one embodiment, the plasma 432 is formed over a wafer 434 mounted on a pedestal 436. In at least one embodiment, the lateral spread of the plasma 432 can be approximately the same as the diameter of the coil 410. In an example of the effect of spatially tuned coupling, the plasma 432 is shown as an ion density profile. Here, the illustrated profile shows the radial distribution of ion density, and the ion density profile of the plasma 432 is represented as the cross-sectional thickness. In at least one embodiment, the plasma 432 has a bone-shaped ion density profile in the x-z plane and is shown to represent the radial ion density profile. In at least one embodiment, the ion density distribution shown in FIG. 4A illustrates an increasing ion density towards the periphery of the plasma 432 compared to the inner region of the plasma 432.

[0100] In at least one embodiment, as the ion density increases towards the periphery of the plasma 432, the deposition rate for PECVD film deposition at the periphery of the plasma 432 can increase. In at least one embodiment, the periphery of the plasma 432 is electromagnetically coupled to the tuned portion 420. In at least one embodiment, the central portion of the plasma 432 is electromagnetically coupled to the detuned portion 424. In at least one embodiment, the ICP antenna 408 comprises a plurality of tuned and detuned portions and can enable the plasma 432 to generate a more complex profile than that shown in FIG. 4A.

[0101] In the x-y plane, the plasma 432 can also have, for example, an approximately circular azimuthal envelope that is close to the circular shape of the coil 410. In at least one embodiment, spatial control of the plasma ion density is enabled by tuning the applied frequency from the RF signal source 426 or tuning the tuned portions of the ICP antenna 408. In at least one embodiment, by tuning and resonating the applied frequency or resonance frequency of the tuned portion 420, the ion density in the peripheral region of the plasma 432 can be significantly enhanced compared to the internal region of the plasma 432.

[0102] In at least one embodiment, the shunt capacitor 412 is a fixed capacitor. In at least one embodiment, the capacitance of the shunt capacitor 412 can be predetermined by the inductance of the coil segment 414 to set a specific resonance frequency of the tuning section 420. In at least one embodiment, the shunt capacitor 412 may be a variable capacitor, whereby the capacitance of the shunt capacitor 412 can be manually or dynamically adjusted to tune the resonance frequency of the tuning section 420 according to process requirements. In at least one embodiment, the resonance frequency may be tuned within the variable capacitance range of the shunt capacitor 412. In at least one embodiment, by tuning the applied frequency from the RF signal source 426 or by tuning the resonance frequency of the tuning section 420, the ion density in the peripheral region of the plasma 432 can be significantly enhanced or reduced compared to the inside of the plasma 432. In at least one embodiment, the tuning may be performed by automated means or at the discretion of the operator. For example, the shunt capacitor 412 can be fixed and the frequency can be systematically swept or changed to periodically decrease and increase the circulating current within the tuning section 420. Alternatively, the frequency may remain fixed and the shunt capacitor 412 is tuned in a systematic manner to periodically vary the resonance frequency f 0 of the tuning section 420. In at least one embodiment, the resulting fluctuations in the circulating current are the same within the tuning section 420.

[0103] In at least one embodiment, by tuning the tuning section 420 to have a resonance frequency that is 10% to 190% of the applied RF frequency, the circulating current within the tuning section can be dynamically adjusted. In at least one embodiment, the circulating current flowing within the tuning section 420 can be adjusted relative to the line current flowing through the untuned section 424 (e.g., the line current does not circulate). In at least one embodiment, the spatially confined currents flowing within the tuning section 420 and the untuned section 424 generate a spatially resolved magnetic field that couples to the plasma 432. In at least one embodiment, the spatial resolution of the magnetic field emitted from the ICP antenna 408 enables the spatial distribution of the ion current within the plasma 432.

[0104] In at least one embodiment, the ratio of the circulating current flowing within the tuning section 420 to the line current flowing within the untuned section 424 can be adjusted in two ways. First, by tuning the resonance frequency f 0 of the tuning section 420. Second, by tuning the applied RF frequency. By either method, in at least one embodiment, the ratio of the applied RF frequency to the resonance frequency of the tuning section 420 can be adjusted to be at least 1:10 to 10:1 or less. In at least one embodiment, at a ratio of 1:1, the applied RF frequency is equal to the resonance frequency and the circulating current is at its maximum magnitude. In at least one embodiment, the resonance curve can be approximately symmetric, and as the ratio increases or decreases from 1:1, the magnitude of the circulating current decreases on either side of the resonance maximum.

[0105] In at least one embodiment, the ratio of the circulating current flowing within the tuned portion 420 can increase as compared to the line current flowing within the untuned portion 424. In at least one embodiment, by adjusting the applied RF frequency to be within 10% to 190% of the tuned portion 420, the ratio of the circulating current within the tuned portion 420 to the line current flowing through the untuned portion 424 can be greater than 1:1. In at least one embodiment, the ratio of the circulating current flowing within the tuned portion 420 to the line current flowing through the untuned portion 424 can be made 2:1 or greater by adjusting the applied RF frequency to be 50% or more of the resonant frequency of the tuned portion 420.

[0106] In the above example, the applied RF frequency is adjusted relative to a constant or fixed resonant frequency of the tuned portion 420. In at least one embodiment, the current ratio can also be adjusted by tuning the resonant frequency of the tuned portion 420 relative to a constant applied RF frequency. In at least one embodiment, the resonant frequency of the tuned portion 420 can be adjusted by tuning the shunt capacitor 412.

[0107] In at least one embodiment, the RF voltage on the ICP antenna 408 generates an electric field that couples to the plasma 432. In at least one embodiment, the higher the electric field strength, the higher the ionization rate and ion density within the plasma 432. In at least one embodiment, due to the spatial distribution of the strength of the electric field emitted from the ICP antenna 408, spatially distinct ion densities can be generated within the plasma 432. In at least one embodiment, the RF voltage appearing across the tuned portion 420 can be adjusted to be different from the RF voltage appearing across the untuned portion 424. In at least one embodiment, the ion density within the region of the plasma 432 coupled to the tuned portion 420 can be spatially distinct from the ion density within the region of the plasma 432 coupled to the untuned portion 424.

[0108] In at least one embodiment, the RF voltage across the tuned portion 420 and the detuned portion 424 can also be adjusted by tuning the resonant frequency of the tuned portion 420 relative to the applied RF frequency. In at least one embodiment, it is possible to adjust the applied RF frequency while keeping the resonant frequency of the tuned portion 420 fixed. In at least one embodiment, by tuning the resonant frequency of the tuned portion 420, or by tuning the applied frequency such that the ratio of the applied frequency to the resonant frequency of the tuned portion 420 is at least 1:10, the RF voltage across the tuned portion 420 can be enhanced compared to the RF voltage across the detuned portion 424. In at least one embodiment, the ratio of the RF voltages across the tuned portion 420 and the detuned portion 424 can be reduced to approximately 1:1 by adjusting the ratio of the applied RF frequency to the resonant frequency to 1:10 or less, or 10:1 or more.

[0109] FIG. 4B shows an exemplary plot 450 of the current ratio between the tuned portion 420 and the detuned portion 424 of the spatially tunable ICP antenna 408 as a function of the applied RF frequency f according to at least one embodiment. In at least one embodiment, the plot 450 can show the effect of spatially controlling resonance on the ICP antenna 408. In at least one embodiment, the curve of the plot 450 may be the low frequency shoulder of the sharp resonance curve of the tuned portion 420. In at least one embodiment, the resonance curve can rise sharply as the applied frequency approaches the resonant frequency f 0 . Here, the frequency ratio is shown on the horizontal axis, and the ratio of the circulating current flowing through the tuned portion (e.g., the tuned portion 420) to the line current flowing through the detuned portion (e.g., the detuned portion 424) is shown on the vertical axis.

[0110] Here, while the applied RF frequency is swept, the resonance frequency remains fixed. In at least one embodiment, an assumed value of the inductance L of the tuning coil segment (e.g., tuning portion 420) can be approximately 2.5 microhenries (μH). In at least one embodiment, the shunt capacitance across the tuning coil segment (e.g., shunt capacitor 412) can have a capacitance of approximately 20 nanofarads (nF). Based on these values, for this circuit, the tuning portion has a resonance frequency f 0 of approximately 715 kHz.

[0111] As can be seen from plot 450, in at least one embodiment, when the applied RF frequency f is approximately 50% of f 0 , the ratio of the tuning portion current to the detuning portion current increases to approximately 2:1. In at least one embodiment, when the applied RF frequency f is approximately 75% of f 0 , the ratio increases to approximately 4:1. In at least one embodiment, the ICP antenna 408 can operate at a closer RF frequency to obtain a larger current ratio if desired. In at least one embodiment, setting the ratio f / f 0 to 1:1 can maximize the circulating current within the tuning portion and the magnitude of the RF voltage across the tuning portion.

[0112] In at least one embodiment, to avoid instability, the ratio f / f 0 can be adjusted to be slightly less than 1:1. In at least one embodiment, the upper limit for f / f 0 can be limited to 0.90 - 0.95. In at least one embodiment, the Q of the tuning portion of the ICP antenna 408 can be decreased to flatten the resonance curve and expand the operating frequency bandwidth. In at least one embodiment, decreasing the Q may reduce the maximum magnitudes of the circulating current and the RF voltage.

[0113] FIG. 5 shows a flowchart 500 summarizing an exemplary method for tuning a spatially tunable ICP antenna, such as ICP antenna 408, to enable static spatial control of a plasma, according to at least one embodiment. In operation 501, a semiconductor processing tool comprising a plasma chamber (e.g., plasma chamber 404) is provided. In at least one embodiment, the semiconductor processing tool may be similar to the semiconductor processing tool 400 shown in FIG. 4A. In at least one embodiment, the semiconductor processing tool may comprise an ICP antenna, such as ICP antenna 408. In at least one embodiment, the ICP antenna comprises a plurality of inductive sections coupled in series (e.g., as shown in RF circuit 200a). In at least one embodiment, at least one of the inductive sections is coupled to a shunt capacitor, such as shunt capacitor 412, to form at least one tuning section. In at least one embodiment, an RF signal source (e.g., RF signal source 204) may be coupled to the ICP antenna to propagate an RF current to the ICP antenna.

[0114] In operation 502, the ICP antenna may be a coil antenna driven at an applied RF frequency generated by an RF signal source, as shown in FIGS. 3A and 3B. In at least one embodiment, the applied RF frequency may be within 10% to 190% of the resonant frequency of one or more tuning sections of the ICP antenna. In at least one embodiment, one or more tuning sections of the ICP antenna may be tuned to generate a ratio of circulating current in a tank circuit (of the one or more tuning sections) to line current flowing through untuned sections of the ICP antenna of at least 1:1. In at least one embodiment, according to plot 450, an applied RF frequency f that is approximately 50% of the resonant frequency f of the tuning section can be set to establish a 2:1 current ratio. 0 of the tuning section.

[0115] In at least one embodiment, the peripheral region of the ICP antenna can comprise a tuned portion, while the internal region of the ICP antenna can comprise a non-tuned portion. In at least one embodiment, a 2:1 current ratio can be established at the periphery of the ICP antenna with respect to the current flowing through the non-tuned internal region (e.g., non-tuned portion 424). In at least one embodiment, the RF voltage across the tuned periphery of the ICP antenna can also be larger by a similar ratio than the RF voltage across the non-tuned internal portion of the ICP antenna.

[0116] In at least one embodiment, it is possible to customize the plasma to have a desired radial and / or azimuthal distribution of ion density, voltage, and other plasma characteristics. In at least one embodiment, multiple (e.g., two or more) tuned portions can be present on the ICP antenna. In at least one embodiment, a plasma (e.g., plasma 432) coupled to an ICP antenna comprising multiple tuned portions can have multiple correlated zones of ion density and other plasma parameters. In at least one embodiment, the plasma characteristics of the multiple plasma zones may be controlled and adjusted relative to each other by the f / f 0 ratio at the multiple tuned portions of the ICP antenna. Referring to the illustrated embodiment shown in FIG. 4A, the spatial distribution of the density of ions and / or other reactive species can be enhanced at the periphery of the plasma compared to the internal region of the plasma. In at least one embodiment, the enhancement of the ion concentration at the periphery can correspond to the increased rate of an etching or deposition process occurring at the periphery of a substrate, such as wafer 434 in FIG. 4A, relative to the central region.

[0117] FIG. 6 shows a flowchart 600 summarizing an exemplary method for tuning a spatially tunable ICP antenna, such as ICP antenna 408, to enable dynamic spatial control of a plasma according to at least one embodiment. In at least one embodiment, in operation 601, the tuning portion of the ICP antenna can be dynamically tuned during a PECVD or plasma etching process. In at least one embodiment, dynamic tuning can be performed in response to random variations in plasma characteristics. In at least one embodiment, dynamic tuning can compensate for variations in the distribution of precursors or plasma gases over the substrate. In at least one embodiment, dynamic tuning may be performed in a pre-programmed manner. In at least one embodiment, dynamic tuning may include periodic tuning and detuning of adjacent tuning portions along the ICP antenna to dynamically shift a high ion density region within a multi-zone plasma. In at least one embodiment, the shift of the ion density from zone to zone may enable spatial control of the deposition flux along the wafer substrate.

[0118] In at least one embodiment, the deposition or etching non-uniformities introduced by a particular showerhead can be compensated for by spatially controlling the plasma. In at least one embodiment, the showerhead may have a low deposition flux from the peripheral region. Under static plasma conditions, the deposited film may have high non-uniformities, such that the film has a greater thickness at its periphery compared to its interior. In at least one embodiment, the dynamic tuning of a multi-zone ICP antenna can periodically increase and decrease the deposition flux in spatially distinct zones of the multi-zone plasma (e.g., both the interior and the periphery). In at least one embodiment, the dynamic tuning may include periodically tuning and detuning the tuned portion of the ICP antenna. In at least one embodiment, spatial control of the electromagnetic coupling along the ICP antenna by such dynamic tuning may enable the deposition of a more uniform film with lower non-uniformities. In at least one embodiment, the dynamic tuning may be performed by dynamically adjusting the shunt capacitance or by dynamically adjusting the applied RF frequency.

[0119] In operation 602, in at least one embodiment, an exemplary method includes adjusting the input impedance of an ICP antenna by tuning a series capacitance (e.g., series capacitor 430 of FIG. 4A) coupled to the ICP antenna. In at least one embodiment, the reactive component of the input impedance of the ICP antenna may depend on the value of the shunt capacitance across the tuned portion of the ICP antenna. Since these values may be adjusted dynamically during the process, the input impedance of the ICP antenna may vary during the process and from process to process. In at least one embodiment, the series capacitance can be tuned to adjust the input impedance at the feed point of the ICP antenna. In at least one embodiment, the feed point impedance is frequency dependent and can be predominantly capacitive reactance or inductive reactance depending on the applied RF frequency.

[0120] In at least one embodiment, the series capacitance may be in series with the capacitance of an ICP antenna that can include a shunt capacitance. When the applied RF frequency is such that the supply point impedance is predominantly inductive, in at least one embodiment, the series capacitance can be adjusted to partially or fully cancel the inductive reactance of the ICP antenna and reduce the overall input impedance. In at least one embodiment, the input impedance of the ICP antenna is reduced. According to at least one embodiment, when the input impedance of the ICP antenna decreases, for a given power level, the peak input voltage of the applied RF signal also decreases, and the RF voltage across the unmatched portion of the ICP antenna may decrease.

[0121] In at least one embodiment, the input impedance at the ICP antenna supply point may be in the hundreds of ohms to thousands of ohms. In at least one embodiment, the output impedance of the RF signal source can be 50 ohms regardless of the frequency. In at least one embodiment, an impedance matching network with a set conversion ratio can be used to match the large impedance differences that may exist, including between the output of the RF signal source and the input of the ICP antenna. In at least one embodiment, by controlling the supply point impedance of the ICP antenna, it is possible to dynamically adjust the series capacitance and maintain the conversion ratio of the impedance matching network. In at least one embodiment, to reduce the conversion ratio and capacitance range of the matching network, the series capacitor can be adjusted to lower the reactive component of the input impedance to the ICP antenna and reduce the overall input impedance. In at least one embodiment, the input voltage to the ICP antenna can also be reduced. In at least one embodiment, the rated voltage of the components within the ICP antenna circuit can be lowered, potentially reducing the capital cost and maintenance cost.

[0122] The following examples are provided to illustrate various embodiments. Here, these examples can be combined with other examples. Therefore, various embodiments can be combined with other embodiments without changing the scope of the invention.

[0123] Example 1 is an apparatus comprising an inductively coupled plasma (ICP) antenna having a plurality of inductances electrically coupled in series, and a capacitor coupled in parallel with one of the plurality of inductances, wherein the ICP antenna comprises a capacitor that is electromagnetically coupled to a plasma.

[0124] Example 2 includes all features of Example 1, wherein the inductance among the plurality of inductances is a first inductance, the capacitor is a first capacitor among a plurality of capacitors, the apparatus further comprises a second capacitor, and the second capacitor is coupled in parallel with a second inductance among the plurality of inductances.

[0125] Example 3 includes all features of Example 2, wherein a third inductance among the plurality of inductances is between the first inductance and the second inductance.

[0126] Example 4 includes all features of Example 1, and further comprises an RF signal source and at least one series capacitor electrically coupled to the ICP antenna.

[0127] Example 5 includes all features of Example 4, wherein the at least one series capacitor is a fixed capacitor, a variable capacitor, or a combination thereof.

[0128] Example 6 includes all features of Example 2, wherein the first capacitor is further coupled in parallel with the first inductance and a fourth inductance, and the fourth inductance and the first inductance are electrically in series with each other.

[0129] Example 7 includes all the features of Example 6, and the second capacitor is coupled in parallel with the second inductance and the fifth inductance, and the fifth inductance is one of the plurality of inductances.

[0130] Example 8 is an inductively coupled plasma (ICP) antenna including a coil, the coil including a first terminal, a second terminal, a plurality of coil segments between the first terminal and the second terminal, and a capacitor coupled in parallel with one of the plurality of coil segments.

[0131] Example 9 includes all the features of Example 8, and the capacitor is above or below the coil segment.

[0132] Example 10 includes all the features of Example 9, and the coil is a spiral coil, and the spiral coil is substantially planar.

[0133] Example 11 includes all the features of Example 10, and the capacitor is a first capacitor of a plurality of capacitors, the coil segment is a first coil segment, and individual capacitors of the plurality of capacitors are electrically coupled in parallel to one or more individual coil segments of the plurality of coil segments.

[0134] Example 12 includes all the features of Example 11, and the first terminal of the first coil segment is at a first radius of the spiral coil, the second terminal of the first coil segment is at a second radius of the spiral coil, the second radius is greater than the first radius, the spiral coil includes a second coil segment, the second coil segment includes a third terminal and a fourth terminal, the third terminal is electrically coupled to the second terminal, the fourth terminal is at a third radius of the spiral coil, the third radius is greater than the second radius, and the second coil segment is substantially concentric with the first coil segment.

[0135] Example 13 includes all the features of Example 12, wherein the coil comprises a third coil segment, the third coil segment is between the first coil segment and the second coil segment, and the third coil segment is electrically coupled in series with the first coil segment and the second coil segment.

[0136] Example 14 includes all the features of Example 13, wherein the first capacitor is coupled to the first coil segment, the device comprises a second capacitor and a third capacitor, the second capacitor is coupled to the second coil segment, and the third capacitor is coupled to the third coil segment.

[0137] Example 15 includes all the features of Example 14, wherein the ICP antenna comprises a first tuning portion including the first capacitor electrically coupled in parallel to any one of the first coil segment, the second coil segment, or the third coil segment, the first coil segment has a first inductance, the second coil segment has a second inductance, the third coil segment has a third inductance, the first capacitor of the plurality of capacitors has a first capacitance, and the first tuning portion is operable to resonate at a first RF frequency.

[0138] Example 16 includes all the features of Example 15, wherein the ICP antenna comprises a second tuning portion including the second capacitor of the plurality of capacitors electrically coupled in parallel to any one of the first coil segment, the second coil segment, or the third coil segment, the second capacitor of the plurality of capacitors has a second capacitance, and the second tuning portion is operable to resonate at a second RF frequency.

[0139] Example 17 includes all the features of Example 16, and the ICP antenna includes a third tuning portion including a third capacitor electrically coupled in parallel to any one of the first coil segment, the second coil segment, or the third coil segment. The third capacitor of the plurality of capacitors has a third capacitance, and the third tuning portion is operable to resonate at a third RF frequency.

[0140] Example 18 is a semiconductor processing tool including a first chamber, a second chamber adjacent to the first chamber, the second chamber being separated from the first chamber by a wall including a dielectric material, and an inductively coupled plasma (ICP) antenna in the first chamber, the ICP antenna including a plurality of inductances, individual inductances of the plurality of inductances being electrically coupled in series with each other, at least one inductance of the plurality of inductances being electrically coupled in parallel to a capacitor, and an RF signal source electrically coupled to the ICP antenna.

[0141] Example 19 is a method for tuning an inductively coupled plasma (ICP), comprising providing an ICP apparatus, wherein the ICP apparatus comprises an ICP antenna having a plurality of inductances, wherein individual inductances of the plurality of inductances are electrically coupled in series with each other, and at least one inductance of the plurality of inductances is electrically coupled in parallel with a capacitor; an ICP antenna; a radio frequency (RF) signal source, wherein the ICP antenna is electrically coupled to the RF signal source, the ICP antenna comprises at least one tuning portion, the at least one tuning portion comprises a first inductance of the plurality of inductances coupled in parallel with the capacitor, the at least one tuning portion comprises a tank circuit having a resonant frequency, the ICP antenna further comprises at least one non-tuning portion, and the at least one non-tuning portion comprises at least a second non-tuning inductance of the plurality of inductances electrically coupled to the at least one tuning portion of the ICP antenna; and driving the ICP antenna by tuning the RF signal source to a frequency such that a ratio of a first current circulating within the at least one tuning portion to a second current flowing through the at least one non-tuning portion is greater than 1:1, wherein the plasma coupled to the ICP antenna is spatially regulated and the rate of the plasma-enhanced process is spatially regulated across the substrate.

[0142] Example 20 includes all features of Example 19, and driving the ICP antenna by tuning the RF signal source comprises tuning the RF signal source to adjust a first electromagnetic field coupled to the tuning portion of the ICP antenna relative to a second electromagnetic field coupled to the non-tuning portion of the ICP antenna, wherein a first concentration of ions in a first portion of the plasma is adjusted relative to a second concentration of ions in a second portion of the plasma, and the second portion of the plasma is coupled to the non-tuning portion.

[0143] Example 21 includes all the features of Example 20 and further includes tuning a series capacitance, the series capacitance being coupled in series to the ICP antenna and the RF signal source, the series capacitance being tuned to adjust the capacitive reactance of the series capacitance, and the input impedance of the ICP antenna being adjusted by adjusting the capacitive reactance of the series capacitance.

[0144] Example 22 includes all the features of Example 21, and the input voltage to the ICP antenna is reduced by tuning the series capacitance to adjust the input impedance of the ICP antenna.

[0145] Example 23 includes a vacuum process chamber and an inductively coupled plasma (ICP) antenna adjacent to the vacuum process chamber, the ICP antenna including a radiating element, the radiating element including one or more radio frequency (RF) resonant sections, and the RF resonant sections including a tank circuit including a capacitor electrically coupled to a segment of the radiating element.

[0146] Example 24 includes all the features of Example 23, wherein the capacitor is a shunt capacitor coupled in parallel to the segment of the radiating element.

[0147] Example 25 includes all the features of Example 23, and the shunt capacitor is any one of a fixed capacitor, a variable capacitor, or a combination thereof.

[0148] Example 26 includes all the features of Example 23, and the radiating element includes one or more non-tuned sections in series coupled to the one or more RF resonant sections, the non-tuned sections including a non-resonant span of the radiating element.

[0149] Example 27 includes all the features of Example 26, and among the one or more asynchronous segments, one asynchronous segment is located between two of the one or more RF resonance sections.

[0150] Example 28 includes all the features of Example 23, and further includes at least one series capacitor coupled in series to the ICP antenna.

[0151] Example 29 includes all the features of Example 28, and the at least one series capacitor is a fixed capacitor, a variable capacitor, or a combination thereof.

[0152] Example 30 includes all the features of Example 23, the radiation element includes a coil, and the coil includes one or more turns between an inner terminal and an outer terminal.

[0153] Example 31 includes all the features of Example 30, and the coil is a flat spiral coil or a helical coil.

[0154] Example 32 includes all the features of Example 30, the one or more RF resonance segments include a capacitor shunt-coupled across a section of the radiation element, and the section of the radiation element includes one or more turns of the coil.

[0155] Example 33 is an inductively coupled plasma (ICP) antenna comprising a radiation element comprising a coil, the coil comprising a first terminal, a second terminal, and one or more coil segments between the first terminal and the second terminal, the coil segments comprising one or more coil segments each including at least one coil winding, and one or more radio frequency (RF) resonance sections, the RF resonance sections comprising one or more RF resonance sections each including a capacitor coupled in parallel with a coil segment.

[0156] Example 34 includes all the features of Example 33, and the one or more capacitors are any one of a fixed capacitor, a variable capacitor, or a combination thereof.

[0157] Example 35 includes all the features of Example 33, the coil is a helical coil, and the helical coil is substantially planar.

[0158] Example 36 includes all the features of Example 33, further includes one or more detuned sections of the radiating element, the detuned section includes a non-resonant coil segment, and the one or more detuned sections are adjacent to the one or more RF resonant sections.

[0159] Example 37 includes all the features of Example 36, the first capacitor is coupled to the first coil segment, the device includes a second capacitor and a third capacitor, the second capacitor is coupled to the second coil segment, and the third capacitor is coupled to the third coil segment.

[0160] Example 38 includes all the features of Example 37, the ICP antenna includes a first tuned portion including the first capacitor electrically coupled in parallel to any one of the first coil segment, the second coil segment, or the third coil segment, the first coil segment has a first inductance, the second coil segment has a second inductance, the third coil segment has a third inductance, the first capacitor of the plurality of capacitors has a first capacitance, and the first tuned portion is operable to resonate at a first RF frequency.

[0161] Example 39 is a method for tuning an inductively coupled plasma (ICP), comprising providing an ICP apparatus, wherein the ICP apparatus comprises an inductively coupled plasma (ICP) antenna comprising a coil, the coil comprising a first terminal and a second terminal, and one or more coil segments between the first terminal and the second terminal; at least one tuning portion comprising a shunt capacitor coupled in parallel with at least one of the one or more coil segments; at least one non-tuning portion comprising at least one of the one or more coil segments without a shunt capacitor; a radio frequency (RF) signal source operable to output a drive frequency, the ICP antenna being electrically coupled to the RF signal source; and driving the ICP antenna such that a ratio of a first current circulating within the at least one tuning portion to a second current flowing through the at least one non-tuning portion is greater than 1:1, wherein a plasma coupled to the ICP antenna is spatially regulated and a rate of a plasma enhancement process is spatially regulated across a substrate.

[0162] Example 40 includes all features of Example 39, and driving the ICP antenna includes tuning the drive frequency of the RF signal source, the drive frequency being within 50% of the resonance frequency of the at least one tuning portion.

[0163] Example 41 includes all features of Example 39, and driving the ICP antenna includes tuning at least one capacitor such that the resonance frequency of the at least one tuning circuit is in a range of 10% to 190% of the drive frequency.

[0164] Example 42 includes all the features of Example 41, and tuning the at least one capacitor includes changing the capacitance of the at least one capacitor during the process, and the capacitance of the at least one capacitor is tuned manually or the capacitance of the at least one capacitor is dynamically tuned during the process.

[0165] Example 43 includes all the features of Example 39 and further includes adjusting the input impedance of the ICP antenna, and the adjustable capacitor is coupled in series to the ICP antenna and is tuned to adjust the input impedance of the ICP antenna.

[0166] In addition to what is described herein, various modifications can be made to the disclosed embodiments and their implementations without departing from their scope. Therefore, the description of the embodiments herein should be construed as illustrative only and not as limiting the scope of the present disclosure. The scope of the present invention should be determined only by reference to the following claims.

Claims

1. An apparatus comprising: An inductively coupled plasma (ICP) antenna comprising a plurality of inductances electrically coupled in series; and A capacitor coupled in parallel with one of the plurality of inductances, wherein the ICP antenna comprises a capacitor that is electromagnetically coupled to a plasma The apparatus comprising.

2. The apparatus according to claim 1, wherein The inductance among the plurality of inductances is a first inductance, the capacitor is a first capacitor among a plurality of capacitors, the apparatus further comprises a second capacitor, and the second capacitor is coupled in parallel with a second inductance among the plurality of inductances.

3. The apparatus according to claim 2, wherein A third inductance among the plurality of inductances is between the first inductance and the second inductance.

4. The apparatus according to claim 1, further comprising An RF signal source and at least one series capacitor electrically coupled to the ICP antenna.

5. The apparatus according to claim 4, wherein The at least one series capacitor is a fixed capacitor, a variable capacitor, or a combination thereof.

6. The apparatus according to claim 2, wherein The first capacitor is further coupled in parallel with the first inductance and a fourth inductance, and the fourth inductance and the first inductance are electrically in series with each other.

7. The apparatus according to claim 6, wherein The second capacitor is coupled in parallel with the second inductance and a fifth inductance, and the fifth inductance is one of the plurality of inductances.

8. An apparatus comprising: An inductively coupled plasma (ICP) antenna comprising a coil, the coil comprising A first terminal; A second terminal; A plurality of coil segments between the first terminal and the second terminal; and A capacitor coupled in parallel with one of the plurality of coil segments The ICP antenna comprising The apparatus comprising.

9. The apparatus according to claim 8, wherein The capacitor is above or below the coil segment.

10. The apparatus according to claim 9, wherein The coil is a helical coil, and the helical coil is substantially planar, apparatus.

11. The apparatus according to claim 10, wherein the capacitor is a first capacitor among a plurality of capacitors, the coil segment is a first coil segment, and each of the plurality of capacitors is electrically coupled in parallel to one or more individual coil segments of the plurality of coil segments, apparatus.

12. The apparatus according to claim 11, wherein the first terminal of the first coil segment is at a first radius of the helical coil, the second terminal of the first coil segment is at a second radius of the helical coil, the second radius is greater than the first radius, the helical coil includes a second coil segment, the second coil segment includes a third terminal and a fourth terminal, the third terminal is electrically coupled to the second terminal, and the fourth terminal is at a third radius of the helical coil, the third radius is greater than the second radius, and the second coil segment is substantially concentric with the first coil segment, apparatus.

13. The apparatus according to claim 12, wherein the coil includes a third coil segment, the third coil segment is between the first coil segment and the second coil segment, and the third coil segment is electrically coupled in series with the first coil segment and the second coil segment, apparatus.

14. The apparatus according to claim 13, wherein the first capacitor is coupled to the first coil segment, the apparatus includes a second capacitor and a third capacitor, the second capacitor is coupled to the second coil segment, and the third capacitor is coupled to the third coil segment, apparatus.

15. The apparatus according to claim 14, The ICP antenna includes a first tuning portion including the first capacitor electrically coupled in parallel to any one of the first coil segment, the second coil segment, or the third coil segment. The first coil segment has a first inductance, the second coil segment has a second inductance, the third coil segment has a third inductance, the first capacitor of the plurality of capacitors has a first capacitance, and the first tuning portion is operable to resonate at a first RF frequency. Device.

16. The device according to claim 15, The ICP antenna includes a second tuning portion including the second capacitor of the plurality of capacitors electrically coupled in parallel to any one of the first coil segment, the second coil segment, or the third coil segment. The second capacitor of the plurality of capacitors has a second capacitance, and the second tuning portion is operable to resonate at a second RF frequency. Device.

17. The device according to claim 16, The ICP antenna includes a third tuning portion including the third capacitor of the plurality of capacitors electrically coupled in parallel to any one of the first coil segment, the second coil segment, or the third coil segment. The third capacitor of the plurality of capacitors has a third capacitance, and the third tuning portion is operable to resonate at a third RF frequency. Device.

18. A semiconductor processing tool, A first chamber, A second chamber, wherein the second chamber is adjacent to the first chamber, and the second chamber is separated from the first chamber by a wall containing a dielectric material. Second chamber, An inductively coupled plasma (ICP) antenna in the first chamber, the ICP antenna comprising a plurality of inductances, individual inductances of the plurality of inductances being electrically coupled in series with each other, and at least one inductance of the plurality of inductances being electrically coupled in parallel to a capacitor. ICP antenna, An RF signal source electrically coupled to the ICP antenna A semiconductor processing tool comprising

19. A method for tuning an inductively coupled plasma (ICP), comprising Providing an ICP apparatus, said ICP apparatus comprising An ICP antenna having a plurality of inductances, wherein individual inductances of said plurality of inductances are electrically coupled in series with each other, and at least one inductance of said plurality of inductances is electrically coupled in parallel with a capacitor; and A radio frequency (RF) signal source, said ICP antenna being electrically coupled to said RF signal source, said ICP antenna comprising at least one tuning section, said at least one tuning section comprising a first inductance of said plurality of inductances coupled in parallel with said capacitor, said at least one tuning section comprising a tank circuit having a resonant frequency, said ICP antenna further comprising at least one non-tuning section, said at least one non-tuning section comprising at least a second non-tuning inductance of said plurality of inductances electrically coupled to said at least one tuning section of said ICP antenna; and Comprising Driving said ICP antenna by tuning said RF signal source to a frequency such that a ratio of a first current circulating within said at least one tuning section to a second current flowing through at least one non-tuning section is greater than 1:1, wherein a plasma coupled to said ICP antenna is spatially regulated and a rate of a plasma enhancement process is spatially regulated across a substrate; and A method comprising

20. The method according to claim 19, wherein Driving said ICP antenna by tuning said RF signal source comprises tuning said RF signal source to adjust a first electromagnetic field coupled to said tuning section of said ICP antenna relative to a second electromagnetic field coupled to said non-tuning section of said ICP antenna, wherein a first concentration of ions in a first portion of said plasma is adjusted relative to a second concentration of ions in a second portion of said plasma, said second portion of said plasma being coupled to said non-tuning section.

21. The method according to claim 20, wherein A method further comprising tuning a series capacitance, the series capacitance being serially coupled to the ICP antenna and the RF signal source, the series capacitance being tuned to adjust the capacitive reactance of the series capacitance, the input impedance of the ICP antenna being adjusted by adjusting the capacitive reactance of the series capacitance. Claim 22 The method according to claim 21, A method in which the input voltage to the ICP antenna is reduced by tuning the series capacitance to adjust the input impedance of the ICP antenna.

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