Systems and methods for radial and azimuthal control of plasma uniformity

Abstract

A system includes a process chamber, a housing defining a waveguide cavity, and a first electrically conductive plate within the housing. The first electrically conductive plate faces the process chamber. The system also includes one or more adjustment devices that can adjust a position of the first electrically conductive plate, and a second electrically conductive plate coupled with the housing between the waveguide cavity and the process chamber. Electromagnetic radiation can propagate from the waveguide cavity into the process chamber via an aperture in the second electrically conductive plate. The system also includes a dielectric plate that encloses the process chamber while being separated from the waveguide cavity, and one or more electronic device banks that send electromagnetic radiation into the waveguide cavity. A plasma is formed when at least one process gas is within the chamber and electromagnetic radiation propagates from the waveguide cavity into the process chamber.

Description

[0001] This application is a divisional application of application number 201880012847.8, filed on January 31, 2018, entitled "SYSTEM AND METHOD FOR RADIAL AND AZIMUTHAL CONTROL OF PLASMA UNIFORMITY". TECHNICAL FIELD

[0002] The present disclosure is in the field of electromagnetic radiation. More specifically, embodiments are disclosed that utilize waveguides and related control systems to provide radial and / or azimuthal control of plasma in a process chamber. BACKGROUND

[0003] Semiconductor processing often generates plasma to produce ionized and / or energy-excited species for interaction with a semiconductor wafer itself or other process-related materials (e.g., photoresist). To generate and / or sustain the plasma, one or more radio frequency (RF) and / or microwave generators are typically employed to generate oscillating electric and / or magnetic fields. The same fields and / or DC fields can also be utilized to direct the ionized and / or energy-excited species to the (semiconductor wafer(s) to be processed. The fields can be generated and / or coupled into a chamber, where the plasma is generated in a variety of ways. Various known methods are often used to match the impedance of the power source (RF generator) to the load (plasma) so that power from the RF generator can be delivered to the plasma without substantial power being reflected back to the RF generator. This is for reasons of energy efficiency as well as to protect the electronic components of the RF generator from damage. Particularly when microwave energy is employed, the reflected power is often directed to a dummy load where the reflected power is dissipated as heat, which must then be removed. Thus, the reflected power causes a double energy waste: energy used to generate the power and energy used to remove the waste heat. SUMMARY

[0004] In one embodiment, a system includes a process chamber, a housing defining a waveguide cavity, and a first electrically conductive plate within the housing. The first electrically conductive plate faces the process chamber across the waveguide cavity. The system also includes one or more adjustment devices that can adjust a position of the first electrically conductive plate and a second electrically conductive plate coupled with the housing between the waveguide cavity and the process chamber. Electromagnetic radiation can propagate from the waveguide cavity into the process chamber via an aperture in the second electrically conductive plate. The system also includes a dielectric plate that encloses the process chamber separate from the waveguide cavity so that the waveguide cavity is not evacuated when the process chamber is evacuated. The system further includes one or more groups of electronic devices that send electromagnetic radiation into the waveguide cavity. A plasma is formed when at least one process gas is within the chamber and electromagnetic radiation propagates from the waveguide cavity into the process chamber.

[0005] In an embodiment, a plasma processing system includes a process chamber operable to be evacuated, one or more process gas supplies to introduce one or more process gases into the process chamber, a housing to define a waveguide cavity, and one or more groups of electronics to transmit electromagnetic radiation into the waveguide cavity. Each group of the one or more groups of electronics matches its drive impedance to an impedance presented by the waveguide cavity to electromagnetic radiation. A first electrically conductive plate is within the housing and distal to the process chamber from the waveguide cavity. At least three adjustment devices are coupled with the first electrically conductive plate and the housing. The adjustment devices are adjustable at least to a position of the first electrically conductive plate and a tilt of the first electrically conductive plate relative to the housing within a range of positions. A second electrically conductive plate is coupled with the housing and interposed between the waveguide cavity and the process chamber. A plurality of apertures are formed in the second electrically conductive plate to allow electromagnetic radiation within the waveguide cavity to propagate into the process chamber via the apertures. A dielectric plate encloses the process chamber while being spaced apart from the waveguide cavity such that the waveguide cavity is not evacuated when the process chamber is evacuated. The waveguide cavity can support eigenmodes between the first and second electrically conductive plates when the first electrically conductive plate is adjusted to eigenmode positions within the range of positions and the one or more groups of electronics transmit electromagnetic radiation into the waveguide cavity. A plasma is formed when at least one process gas is within the chamber and electromagnetic radiation propagates from the waveguide cavity into the process chamber.

[0006] In an embodiment, a method for generating plasma for processing a workpiece includes introducing one or more process gases into a process chamber. The process chamber is at least partially enclosed with a dielectric plate capable of supporting a differential pressure corresponding to an evacuation of the process chamber. The method also includes propagating electromagnetic radiation into a waveguide cavity disposed adjacent to the process chamber. The waveguide cavity is at least partially bounded by a first electrically conductive plate facing the process chamber and across the waveguide cavity from the process chamber and a second electrically conductive plate between the waveguide cavity and the dielectric plate. The second electrically conductive plate forms apertures allowing the electromagnetic radiation to propagate into the chamber via the second electrically conductive plate, via the dielectric plate. The method further includes igniting a plasma from the process gases and sustaining the plasma with power supplied by the electromagnetic radiation propagating into the process chamber via the apertures of the second electrically conductive plate.

[0007] In an embodiment, a method for providing electromagnetic radiation in a process chamber for powering a plasma includes introducing one or more process gases into the process chamber and propagating electromagnetic radiation from at least two locations P and Q into a waveguide cavity disposed adjacent to the process chamber. The waveguide cavity is separate from the process chamber such that the process chamber can be evacuated without evacuating the waveguide cavity while electromagnetic radiation within the waveguide cavity can still propagate into the process chamber. Locations P and Q are at respective angles Θ p and Θ qThe method includes providing electromagnetic radiation in a waveguide cavity at a microwave frequency ω and a rotational frequency Ω. The method further includes igniting a plasma from the process gas and sustaining the plasma with power supplied from the electromagnetic radiation propagating from the waveguide cavity into the process chamber.

[0008] In an embodiment, a system for generating a plasma includes a process chamber that can be evacuated and a waveguide cavity disposed adjacent the process chamber. The waveguide cavity is separate from the process chamber without blocking propagation of electromagnetic radiation in the waveguide cavity into the process chamber. The system also includes one or more process gas supplies for introducing one or more process gases into the process chamber and a first set of electronic devices and a second set of electronic devices. Each of the first set of electronic devices and the second set of electronic devices transmits electromagnetic radiation into the waveguide cavity. The system further includes a controller that provides a respective first input waveform and a second input waveform to each of the first set of electronic devices and the second set of electronic devices. Each of the first input waveform and the second input waveform has a microwave frequency ω and the first input waveform and the second input waveform have respective amplitudes that, when amplified by the set of electronic devices, provide a rotational frequency Ω to the electromagnetic radiation in the waveguide cavity. A plasma is formed when at least one of the one or more process gases is in the chamber and the electromagnetic radiation propagates from the waveguide cavity into the process chamber.

[0009] In an embodiment, a method for plasma processing in a process chamber includes introducing one or more process gases into the process chamber. The process chamber is disposed adjacent a waveguide cavity and the waveguide cavity is separate from the process chamber without blocking propagation of electromagnetic radiation in the waveguide cavity into the process chamber. The method also includes propagating electromagnetic radiation into the waveguide cavity. The electromagnetic radiation is provided at a microwave frequency ω. A first portion of power supplied in the waveguide cavity is supplied by a portion of the electromagnetic radiation resonating in a TE mode in the waveguide cavity. A second portion of power supplied in the waveguide cavity is supplied by a portion of the electromagnetic radiation resonating in a second TE mode in the waveguide cavity. The method further includes igniting a plasma from the process gas and sustaining the plasma with power supplied from the electromagnetic radiation propagating from the waveguide cavity into the process chamber.

[0010] In one embodiment, a method for processing a workpiece in a process chamber includes placing the workpiece in the process chamber. The process chamber is disposed adjacent to a waveguide cavity. The waveguide cavity is separate from the process chamber without blocking propagation of electromagnetic radiation within the waveguide cavity into the process chamber. The method also includes processing the workpiece with a first plasma and processing the workpiece with a second plasma. Each of the first plasma and the second plasma is generated by introducing one or more process gases into the process chamber, propagating electromagnetic radiation into the waveguide cavity, igniting a plasma from the process gases, and sustaining the plasma with power supplied by the electromagnetic radiation propagating from the waveguide cavity into the process chamber. At least a portion of the power for the first plasma is supplied by electromagnetic radiation resonating in a first TE mode within the waveguide cavity, and at least a portion of the power for the second plasma is supplied by electromagnetic radiation resonating in a second TE mode within the waveguide cavity. The order of the first TE mode is different than the second TE mode.

[0011] Additional embodiments and features are set forth in part in the description that follows and, in part, will be apparent to those skilled in the art from the description, or can be learned by practice of the application. The features and advantages of the present application can be realized and attained by means of the instruments, combinations and methods described in this specification. A person skilled in the art will readily recognize from the disclosure herein, that alternative embodiments of the disclosed features can be BRIEF DESCRIPTION OF DRAWINGS

[0012] The present disclosure can be understood with reference to the following detailed description in conjunction with the following figures, wherein like numerals indicate like elements, and in which:

[0013] Figure 1 The main elements of a plasma processing system according to an embodiment are schematically shown.

[0014] Figure 2A is a schematic isometric view showing a portion of a plasma processing system according to an embodiment.

[0015] Figure 2B is a schematic top plan view of an electrically conductive plate showing a portion of a plasma processing system according to an embodiment. Figure 2A is a schematic top plan view of an electrically conductive plate showing a portion of a plasma processing system according to an embodiment. is a schematic top plan view of an electrically conductive plate showing a portion of a plasma processing system according to an embodiment.

[0016] Figure 3 is a schematic diagram showing main components of a system for providing microwaves to a plasma chamber with a waveguide according to an embodiment.

[0017] Figure 4 is a schematic cross-sectional view of a portion of a plasma processing system showing adjustment of a position of a movable plate within a waveguide cavity according to an embodiment.

[0018] Figure 5A is a schematic diagram showing a region of an RF gasket for reducing microwave leakage between a movable plate and a housing according to an embodiment. Figure 4

[0019] Figure 5B is a schematic diagram showing a region of a first RF choke for reducing microwave leakage between a movable plate and a housing according to an embodiment. Figure 4

[0020] Figure 5C is a schematic diagram showing a region of a second RF choke for reducing microwave leakage between a movable plate and a housing according to an embodiment. Figure 4

[0021] Figure 5D is a schematic diagram showing a region of a third RF choke for reducing microwave leakage between a movable plate and a housing according to an embodiment. Figure 4

[0022] Figure 6 is a schematic cross-sectional view of a portion of a plasma processing system showing most features of a plasma processing system including Figure 4 according to an embodiment.

[0023] Figure 7 is a schematic cross-sectional view of a portion of a plasma processing system showing most features of a plasma processing system including Figure 6 according to an embodiment.

[0024] Figure 8 is a schematic cross-sectional view of a portion of a plasma processing system showing most features of a plasma processing system including Figure 7 according to an embodiment.

[0025] Figure 9 is a schematic cross-sectional view of a portion of a plasma processing system showing similar features to a plasma processing system including Figure 7 according to an embodiment.

[0026] Figure 10 is a schematic cross-sectional view of a portion of a plasma processing system showing most features of a plasma processing system including Figure 4 Fig. and​​​​Figure 7 schematic cross-sectional view of a portion of a plasma processing system showing most features and operational concepts of a plasma processing system according to embodiments.

[0027] Figure 11 is a schematic cross-sectional view of a portion of a plasma processing system showing most features and operational concepts of a plasma processing system according to embodiments. Figure 10 schematic cross-sectional view of a portion of a plasma processing system showing most features and operational concepts of a plasma processing system according to embodiments.

[0028] Figure 12 is a schematic cross-sectional view of a portion of another plasma processing system showing most features and operational concepts of a plasma processing system according to embodiments. Figure 10 schematic cross-sectional view of a portion of another plasma processing system showing most features and operational concepts of a plasma processing system according to embodiments.

[0029] Figure 13 shows an exemplary pattern of process variation on a workpiece.

[0030] Figure 14 shows the effect of a rotating wave process on workpiece processing according to embodiments.

[0031] Figure 15 shows certain radial eigenmodes that can be excited within a chamber having chamber walls according to embodiments.

[0032] Figure 16 shows the location of peak electric field intensity corresponding to each eigenmode shown in Figure 15

[0033] Figure 17 is a flowchart of a method of generating plasma for processing a workpiece according to embodiments.

[0034] Figure 18 is a flowchart of a method of providing electromagnetic radiation in a process chamber for powering a plasma according to embodiments.

[0035] Figure 19 is a flowchart of a method for plasma processing in a process chamber according to embodiments.

[0036] Figure 20 is a flowchart of a method 630 for processing a workpiece in a process chamber according to embodiments.

[0037] Figure 21A shows a workpiece after processing with a nominal plasma process according to embodiments that produces different results in an outer region and an inner region.

[0038] Figure 21B schematically shows a procedure to implement a process recipe according to embodiments in which a first process segment is conducted at a nominal power, and a second process segment subsequently continues for an additional time increment.​ DETAILED DESCRIPTION

[0039] Figure 1 The major elements of a plasma processing system 100 according to embodiments are schematically shown. The system 100 is depicted as a single wafer semiconductor wafer processing system, but it will be apparent to those skilled in the art that the techniques and principles herein can be applied to plasma processing systems for any type of workpiece (e.g., articles that are not necessarily wafers or semiconductors). The processing system 100 includes a housing 110 for a wafer interface 115, a user interface 120, a process chamber 130, a controller 140, and one or more power supplies 150. The process chamber 130 includes one or more pedestals 135 on which the wafer interface 115 can place a workpiece 50 (e.g., a wafer, but can be a different type of workpiece) for processing. A vacuum 160 (e.g., one or more vacuum pumps) can operate to evacuate the process chamber 130, and one or more gas supplies 155 can be connected to introduce process gases into the process chamber 130. One or more radio frequency or microwave generators (RF Gen) 165 generate plasma within the process chamber 130 at one or more radio frequency or microwave frequencies process power. (Electromagnetic radiation provided by embodiments herein can be referred to as "microwave" in this disclosure, though the radiation can be in the microwave, radio frequency, or other portion of the electromagnetic spectrum.) The RF Gen 165 can be external or internal to the system 100, and can take the form of one or more electronic device groups, which are further described later. The RF Gen 165 can send microwaves in a waveguide cavity 167, which can be disposed above or below the process chamber 130, and in some embodiments, can be disposed in the housing 110. The waveguide cavity 167 can be connected to the process chamber 130 by a waveguide 170, which can be a hollow tube or other structure that guides the microwave energy from the waveguide cavity 167 to the process chamber 130. The waveguide 170 can be connected to the process chamber 130 by a window 175, which can be a dielectric window that transmits the microwave energy from the waveguide 170 to the process chamber 130. The window 175 can be a ceramic window, a quartz window, or other dielectric window that transmits microwave energy. The waveguide 170 can be connected to the process chamber 130 by a waveguide 180, which can be a hollow tube or other structure that guides the microwave energy from the waveguide 170 to the process chamber 130. The waveguide 180 can be connected to the process chamber 130 by a window 185, which can be a dielectric window that transmits the microwave energy from the waveguide 180 to the process chamber 130. The window 185 can be a ceramic window, a quartz window, or other dielectric window that transmits microwave energy. Figure 1 and Figure 2AThe waveguide cavity 167 is shown above the chamber 130. The waveguide cavity 167 can be a cylindrical cavity, although this is not strictly required. The process chamber 130 is proximate to the waveguide cavity 167, and is bounded adjacent to the waveguide cavity 167 by a plate 169 formed of a dielectric material that is permeable to microwaves, but impermeable to air or process gases utilized in the chamber 130. Thus, when the chamber 130 is evacuated, the dielectric plate 169 can support a pressure differential between the waveguide cavity 167 and the chamber 130, while allowing microwave propagation within the waveguide cavity 167 to the chamber 130. The dielectric plate 169 can be formed, for example, of a refractory material (such as silicon dioxide, silicon nitride, or intermediate silicon oxynitride compounds), a ceramic (such as aluminum oxide, yttrium oxide, etc.), a plastic, and / or a polymer. In some embodiments, a plurality of hollow regions are formed on the lower surface of the dielectric plate 169. This can help plasma ignition, particularly at relatively high pressures (e.g., about 1 Torr or higher) or low power conditions, by helping to disrupt plasma surface modes that can form on the lower surface of the dielectric plate 169. Other structures can also be present between the waveguide cavity 167 and the process chamber 130, as discussed later.

[0040] The elements shown as part of the system 100 are listed by way of example and are not exhaustive. Numerous other possible elements can also be included, such as: gas and / or vacuum plumbing, pressure and / or flow controllers; electrodes, magnetic cores, and / or other electromagnetic devices; mechanical, pressure, temperature, chemical, optical, and / or electronic sensors; viewing and / or other access ports, etc., but are not shown for clarity of illustration. Internal connections and cooperation of the elements shown within the system 100 are also not shown for clarity of illustration. In addition to the RF generator 165, other utilities (such as gas supplies 155, vacuum 160, and / or general electrical power 170) can also be connected to the system 100. Similar to the elements shown in the system 100, the utilities shown as connected to the system 100 are intended to be illustrative and not exhaustive; other types of utilities (such as heated or cooled fluids, pressurized air, network capabilities, waste disposal systems, etc.) can also be connected to the system 100, but are not shown for clarity of illustration.

[0041] Figure 2A is a schematic isometric view showing a portion of a plasma processing system 200, including the waveguide cavity 167, the microwave input 166 sending microwaves into the waveguide cavity 167, the process chamber 130, and the workpiece 50 therein. The dashed line 2B-2B’ represents Figure 2BThe plane of the cross-sectional view shown. In the system 200, the housing 105 defines both the waveguide cavity 167 and the process chamber 130, and the process chamber 130 is substantially radially symmetric about the co-axial of the waveguide cavity 167. Microwaves propagate from the microwave input 166 into the waveguide cavity 167 via the microwave input opening 162, and then into the process chamber 130 via the slots 168 of the conductive plate 137 to provide energy for igniting and / or sustaining the plasma 60. The conductive plate 137 can be formed of, for example, metal, but can also be formed of other conductive materials, or conductive materials partially or completely coated with protective (and not necessarily conductive) materials. In Figure 2A and Figure 2B In the embodiment shown, the waveguide cavity 167 is defined by a dielectric plate 169 facing and possibly in contact with the conductive plate 137. The dielectric plate 169 can be formed of, for example, refractory materials (multiple refractory materials) such as silicon dioxide, silicon nitride, or intermediate compounds (e.g., silicon oxynitride); ceramics (multiple ceramics) such as aluminum oxide, yttrium oxide, etc.; plastics (multiple plastics) and / or polymers (multiple polymers). The conductive plate 137 forms slots 168 that allow microwaves to propagate into the process chamber 130 via the dielectric plate 169. The slots 168 can form, for example, a radial line slot antenna. The pedestal 135 is configured to present the workpiece 50 to the plasma 60 for processing. The process chamber 130 can include ports and / or mechanical openings (not shown) for inserting and / or extracting the workpiece 50, introducing gases to form the plasma 60, removing the plasma and gaseous reaction products, sensing, viewing, etc. An advantage of the conductive plate 137 is that it can be a good thermal conductor to help remove heat generated by the plasma 60 and by displacement currents within the dielectric plate 169. Figure 2B is a schematic top plan view showing the conductive plate 137, showing the dielectric plate 169 exposed via the slots 168.

[0042] Figure 2A 、 Figure 4 and Figures 6 to 10 The orientation of the process chamber, waveguide cavity, etc. shown is common, but not required for operation of the system herein. For example, Figure 2A A workpiece 50 (which can be a wafer) is shown disposed on top of the pedestal 135, which can be a wafer chuck, where the workpiece can be held in place with gravity at least during transfer operations. Thus, in the following description, when the term "height" is used, it should be taken to mean position or distance and not necessarily in the vertical direction. Similar terms such as "vertical" and "top" do not limit the embodiments to the orientation shown, but should be understood to be modified according to other orientations in which the embodiments can operate.

[0043] Because the walls of the system 200 and the conductive plate 137 are equipotential, the waveguide cavity 167 can support eigenmodes - microwave propagation modes in which, for example, the height dl of the waveguide cavity 167 is a multiple of the half-axial wavelength of the microwaves within the waveguide cavity 167, such that the waveguide cavity 167 resonates at the corresponding microwave frequency. That is, when dl = m2π / k z , the eigenmode forms at the resonant frequency of the waveguide cavity 167. Here, the axial wave number k z is defined as where ω is the angular frequency (ω = 2πf), f is the microwave frequency, m is a positive integer, and c is the speed of light, and κ is the radial wave number, the boundary conditions on the cavity sidewalls satisfy R for the radial wave number (i.e., J' m (y' mn ) = 0 and κ = y' mn / R, where J' m is the Bessel function of the first kind of order m, and y' mn is the Bessel function of the second kind of order m).

[0044] For example, in the system 200, one value of dl is about 62 mm when a typical microwave frequency of 2.45 GHz is used, but can vary depending on the shape and pattern of the slots on the conductive plate 137, slight variations in materials, the exact geometry of the microwave input opening 162, etc. The value of dl that causes the waveguide cavity 167 to support an eigenmode can be designated herein as the "eigenmode position." The eigenmode within the waveguide cavity 167 advantageously maximizes the power delivery from the electron device set into the plasma 60 and minimizes the power reflected back to the electron device set. (The thickness of the dielectric plate 169 and the height of the process chamber 130 can also be designed to support the operation of the process chamber 130 at the same microwave frequency in an eigenmode, as discussed later.)

[0045] Providing the dielectric plate 169 with a thickness and dielectric constant can also help to support resonance within the dielectric plate 169 at the same frequency, thereby supporting the eigenmode within the waveguide cavity 167. This can be expressed as the condition d2 = m2π / k dz , where the axial wave number k dz is defined as ε dis the dielectric constant (or effective dielectric constant if the dielectric plate 169 is formed of multiple materials) of the dielectric plate 169, m is any positive integer, and the radial wave number K is defined as above. The reason this condition is helpful is because of the ignition of the plasma 60, which helps to provide a high field strength directly below the dielectric plate 169. The plasma 60 can tend to form and / or concentrate at the closest point in the process chamber 130 to the dielectric plate 169 (where the field coupled through the plate 137 is the strongest). Also, while the total effective height of the chamber 130 can not be critical, it can also be selected to support the eigenmode operation of the process chamber 130. This condition can be expressed as a net "electric height," which is a multiple of the half- wavelength of the microwaves to be used, to maximize the electromagnetic field strength throughout the process chamber 130, i.e., Again, for the same reasons as mentioned above with respect to the waveguide cavity 167, it can be difficult to ensure the eigenmode condition when the conductive plate 137, the dielectric plate 169, and the process chamber 130 have fixed structures.

[0046] Variations in the size of the housing 105, variations in the material, etc., the exact configuration of the slots 168 in the conductive plate 137, the distribution of the plasma 60 below the dielectric plate 169, and / or asymmetric features associated with the waveguide cavity 167 (such as sensors, fasteners, ports, etc.) can globally or everywhere shift the effective value of the eigenmode location within the waveguide cavity 167. Thus, while the housing 105 and the conductive plate 137 can be manufactured with dl defined for the purpose of the eigenmode location, the actual value dl can not be the desired eigenmode location. Apparatus and methods for adjusting dl and other dimensions of the cavities and chambers herein will be disclosed below in connection with Figures 4 to 6 and Figures 10 to 12 .

[0047] The optimal thickness of the dielectric plate 169 can also be determined by other requirements, such as cost, size, weight, mechanical strength, and ability to maintain a vacuum seal above the process chamber 130. The size of the process chamber 130 can be designed to accommodate workpieces 50 up to 300 mm or 450 mm in diameter (e.g., wafers nominally about 12 inches or about 18 inches in diameter). Thus, it can be necessary for the dielectric plate 169 to support a vacuum pressure differential over an area of about 0.15 m 2 to 0.25 m 2 in diameter, which exerts a net force of about 22 to 40 pounds at normal atmospheric pressure. When the dielectric plate 169 is formed of a refractory material with a dielectric constant of about 4 or a ceramic with a dielectric constant of about 10, a thickness less than about 10 mm can be too fragile, while a thickness greater than about 80 mm can be too expensive, large, and heavy. Within this exemplary range, as discussed above, the exact thickness to be used can be optimized according to the wavelength of the microwave radiation to be used and the actual dielectric constant of the material to be used.

[0048] Figure 3is a schematic diagram showing the main components of a system 300 for providing microwaves to a plasma chamber employing a waveguide. The waveguide 210 of the system 300 can be, for example, a Figure 1 and Figure 2A waveguide cavity 167. Generally, the system 300 supplies power to the waveguide 210 at two locations indicated by P and Q in Figure 3 . The locations P and Q are generally driven at a common frequency (by the electronics sets 225(1), 225(2) described below) with a phase offset, which can correspond to an angular offset between P and Q around the circumference of the waveguide 210. A coordinate reference frame is shown within the waveguide 210. The axial direction z represents distance along the cylindrical axis that is concentric with the waveguide 210; that is, the direction z is into and out of the plane of the Figure 3 . The radial direction r represents distance from the cylindrical axis. The azimuthal direction Θ represents angular position around the cylindrical axis. As shown, the location P is taken as the origin of the Θ direction.

[0049] Thus, the waveguide 210 can be viewed as a dual-driven waveguide; the dual-driven mode of operation provides high microwave energy density from two sets of drive electronics rather than a single set operating at double the power. Using two (or more) sets of drive electronics can be advantageous, each set operating at lower power than a single set operating at high power. The set of electronics operating at higher power can require components with high voltage, current, or heat dissipation ratings, which can be far more expensive or more difficult to obtain than components for the lower power sets. For example, low-cost and high-quality microwave field effect transistors (FETs) have recently become available for use in the electronics sets 225 herein, but such high-voltage, current, and / or power dissipation FETs remain expensive or difficult to obtain.

[0050] Operation of the system 300 is best understood as beginning with the signal generator 215, which provides two microwave signals 220(1), 220(2) at the same frequency, but which can have a phase offset relative to each other, which can correspond to a mechanical offset between the drive locations. For example, if the locations P and Q are 90 degrees apart around the circumference of the waveguide 210 from each other, the nominal phase offset should be π / 2. Determining and controlling the phase offset correction is discussed below. In certain embodiments, the signal generator 215 can control the frequency and / or amplitude of the signals 220(1), 220(2) as well as their phase. Control of the frequency is applied to tune the system 300 so that an eigenmode condition can be established in the waveguide 210 and the adjacent process chamber. This can be done to electronically correct for difficult-to-control irregularities in waveguide and chamber dimensions, materials, asymmetric chamber features, etc., although mechanical approaches can also be taken (see, e.g., the Figures 4 to 6 figure and Figures 10 to 12The application of amplitude control is to provide rotational mode control, thereby smoothing local irregularities in the generated plasma, as discussed further below (see, for example, [Figure number missing]). Figure 13 , Figure 14 ).

[0051] Microwave signals 220(1), 220(2) drive circuits, referred to as a first electronics group 225(1) and a second electronics group 225(2). Each electronics group 225(1), 225(2) begins with a solid-state amplifier 230, which boosts the power of the corresponding microwave signal 220(1), 220(2) to generate amplified microwave signals 235(1), 235(2). As discussed above, the solid-state amplifier 230 may include one or more microwave FETs. Each amplified microwave signal 235(1), 235(2) enters and passes through a circulator 240, which protects the corresponding solid-state amplifier 230 from power reflection from waveguide 210. The circulator 240 thus transfers input power from the solid-state amplifier 230 to the corresponding tuner 250 while shunting any power reflected back into the dummy load 245.

[0052] Tuner 250 adjusts the impedance experienced by the amplified microwave signals 235(1), 235(2) to match the impedance presented by components such as coaxial-to-waveguide converter 265, waveguide 210, and adjacent process chambers (e.g., Figure 1 The process chamber 130, Figure 3 (Not shown in the image). Tuner 250 may be, for example, a tripole stub tuner. The amplified tuned signal then passes through a corresponding coaxial-to-waveguide converter 265 and into a waveguide with a radiation aperture 270 (corresponding to...). Figure 2A The microwave input 166 is marked with an illustrative symbol, and the microwave input 166 enters the waveguide 210 at the corresponding waveguide of the microwave input opening 162.

[0053] As part of the tuning required to achieve acceptable impedance matching, tuner 250 can alter the phase of the signal delivered to waveguide 210 such that, although the signal is supplied at locations with a mechanical phase offset around the outer periphery of waveguide 210, the signal itself may no longer have the same electrical phase offset. For example, if P and Q are mechanically offset by 90 degrees, the tuner can shift the phase offset between the microwaves at P and Q to a value other than π / 2. Therefore, asymmetric elliptical or linear rotational modes can be excited, rather than symmetric circular rotational modes within waveguide 210. This asymmetry in the microwave configuration can subsequently lead to adjacent process chambers (e.g., Figure 1 , Figure 2Aprocess aberrations in the process chamber 130 (e.g., in a process chamber in which plasma is powered by microwaves in the waveguide 210). For example, an asymmetric microwave configuration can result in a correspondingly asymmetric plasma, and thus a locally skewed plasma etch depth.

[0054] One way to address the above-described asymmetry is to provide electrical correction to the phase delay between the microwave signals 220(1) and 220(2), and thus the amplified microwave signals 235(1) and 235(2). For example, the dual-phase signal generator 215 can receive a correction signal 313 from the signal controller 312, which provides information for adjusting the signals 220(1), 220(2). For example, the correction signal 313 can direct the dual-phase signal generator 215 to provide a corrected or target phase offset between the microwave signals 220(1), 220(2). Thus, in the system 300 having a mechanical offset of π / 2 between the P and Q points, the phases of the microwave signals 220(1), 220(2) differ from each other by π / 2 or π / 2 plus or minus a target phase difference, such that the measured phase difference at the P and Q points is as desired, as discussed below. In another example, the correction signal 313 can direct the dual-phase signal generator 215 to boost and / or attenuate one or both of the microwave signals 220(1), 220(2), which can advantageously help to maintain a circular rotation of the microwave field.

[0055] Monitoring antennas 211(1) and 211(2) are provided at locations across waveguide 210 that are 180 degrees from points P and Q, respectively, and provide analog signals to signal controller 312 via their respective connections 318(1) and 318(2). These measurements within waveguide 210 itself will capture any phase and / or amplitude offsets introduced by tuner 250. Monitoring antennas 211 can monitor either the electric field component or the magnetic field component of the microwaves in waveguide 210. The locations of monitoring antennas 211(1) and 211(2) across waveguide 210 that are 180 degrees from points P and Q (or at least 30 degrees from either of P and Q for each antenna 211) can cause the signals returned to signal controller 312 to include effects of waveguide 210 that are not easily monitored by monitoring antennas located at points P and Q. Signal controller 312 can receive signals from monitoring antennas 211(1) and 211(2) via their respective connections 318(1) and 318(2), and can determine the amplitudes of the signals at points P and Q and the phase offset between the signals at points P and Q. For example, signal controller 312 can perform in-phase and quadrature-phase demodulation (IQ demodulation) to measure the amplitudes and phase offset of the signals from monitoring antennas 211(1) and 211(2). Signal controller 312 can then use the measured phase offset and / or amplitude to calculate and provide a corresponding digital correction signal 313 to dual-phase signal generator 215. Digital correction signal 313 can be selected to be a desired phase offset (e.g., a value of π / 2) or an offset from an assumed desired phase difference (e.g., when the desired phase difference is obtained, the correction factor is zero). Alternatively, the digital correction signal can be selected to adjust the amplitude of one or both of microwave signals 220(1), 220(2). Dual-phase signal generator 215 can then provide microwave signals 220(1) and 220(2) with the phase offset and / or amplitude such that when the microwave signals propagate through the system, the phase offset between points P and Q is driven to the desired phase difference, and / or the amplitudes measured at points P and Q are as desired.

[0056] Optionally, a user input device 314 can provide one or more target parameters 316 to the signal controller 312. The user input device 314 can be implemented in various ways, such as by physical switches providing output directly received by the signal controller 312, or as part of system management hardware and software that obtains the target parameters from a user interface (e.g., a keyboard, other buttons, or a graphical user interface (GUI)). The target parameters 316 can include, for example, a desired phase difference as measured at the monitor antennas 211(1) and 211(2), or an amplitude adjustment to either or both of the microwaves driven into the waveguide 210. The target parameters 316, along with the analog signals from the monitor antennas 211(1) and 211(2), can be utilized by the signal controller 312 to generate the digital correction signal 313. For example, when a target phase difference is utilized, the digital correction signal 313 can first be generated based on the signals from the monitor antennas 211(1) and 211(2), and then the digital correction signal 313 can be adjusted by adding or subtracting the target parameters 316. Once the digital correction signal 313 is sent, the dual-phase signal generator 215 can provide the signals 220(1) and 220(2) with the corresponding offset until the phase offset between the P and Q points is driven according to the target parameters, and the digital correction signal 313 is driven to its target value or zero. In another example, when a target amplitude adjustment is utilized, the dual-phase signal generator 215 can adjust the amplitude of either or both of the signals 220(1), 220(2) in response thereto.

[0057] As disclosed herein, the optional user input device 314 can thus provide a useful independent degree of freedom for optimizing a semiconductor processing system, including the system 300 or other systems with similar capabilities. For example, a corresponding semiconductor processing system can be optimized by processing (e.g., etching) wafers. Each wafer can be processed with the same processing parameters, except for different target parameters entered into the user input device 314. System performance can be evaluated by wafer measurements indicative of etching system performance (e.g., etch rate, selectivity, line width variation due to etching, etc.), as well as system monitoring (e.g., system settling time, end point detection parameters, etc.). Optimal values for the target parameters can then be selected based on the wafer measurements, system monitoring, and / or combinations thereof.

[0058] Those skilled in the art will appreciate that while the signal controller 312 cooperates with the dual phase signal generator 215 to adjust the phase of the microwave signals 220(1) and 220(2), the tuner 250 continues to adjust the impedance match to minimize reflected power. Thus, the system 300 does not sacrifice impedance matching, but rather provides additional capability for phase and / or amplitude adjustment of the electronic device sets 225(1) and 225(2) to optimize plasma symmetry in the process chamber adjacent to the waveguide 210. That is, in embodiments, during operation of the system 300, the signal generator 215 adjusts the phase offset while the tuner 250 provides the impedance match. In other embodiments, during operation of the system 300, the signal generator 215 adjusts the amplitude while the tuner 250 provides the impedance match.

[0059] Embodiments herein recognize that as wafer size increases and the geometries produced in semiconductor manufacturing decrease, the need for uniformity control of all aspects of the processing environment around the wafer increases. As such, embodiments herein adjust the microwave configuration that produces the plasma not only to match impedance, but also to adjust phase and / or amplitude after matching impedance for improved symmetry of the plasma produced around the wafer. Plasma asymmetry can be caused by many reasons (e.g., mechanically asymmetric ports for gas or plasma input and output, sensors, wafer placement, wafer flat, cable length, material variations of any of the above components, etc.) even when careful attention is paid to process chamber symmetry, wafer position in the process chamber, etc. To correct for these reasons, in addition to impedance matching, additional degrees of control can provide additional and useful tools to improve uniformity of plasma processing. While the system 300 can provide some control by electronically adjusting amplitude and phase, further mechanical and electrical adjustments described below are also useful.

[0060] Figure 4 is a schematic cross-sectional view showing a portion of a plasma processing system 400 that adjusts the height dl of a movable conductive plate 420 within a waveguide cavity 467. In the system 400, a conductive plate 437 coupled with the housing 405 forms a lower boundary of the waveguide cavity 467. A dielectric plate 469 is adjacent to and in direct contact with the conductive plate 437. Similar to the discussion above in connection with Figure 2A dl and d2, respectively, affect the ability of the waveguide cavity 467 and the dielectric plate 469 to support eigenmodes. While frequency adjustment can be used to adjust one or the other of these arrangements to support eigenmodes, frequency adjustment can not simultaneously establish eigenmode conditions in both the waveguide 467 and the dielectric plate 469. That is, additional adjustment degrees of freedom are useful.

[0061] System 400 includes one or more adjustment devices 410 coupled to housing 405 and movable conductive plate 420. The movable conductive plate 420 faces process chamber 430 across microwave cavity 467, i.e., plate 420 is located on the distal side of waveguide cavity 467 from process chamber 430. The adjustment devices 410 are... Figure 4 The image shows a screw, but as discussed below, many other types of adjusting devices can be used. Figure 4 In the illustrated embodiment, device 410 extends through opening 412 in ceiling 415 of housing 405. The height of each device 410 and the corresponding height of movable conductive plate 420 within housing 405 can be adjusted using corresponding nuts 411. This additional degree of freedom allows, for example, first tuning of microwave frequencies to support eigenmode conditions within plate 469; then adjustment of d1 such that movable conductive plate 420 is in an eigenmode position within waveguide 467. By adjusting each of these structures to support its corresponding eigenmode, effective coupling and high field strength (e.g., for igniting plasma) are provided at the lower surface of dielectric plate 469. d3 represents the height of dielectric plate 469 above the floor surface of process chamber 430 and will be at least partially limited by providing support for the workpiece support and the workpiece itself (e.g., Figure 2A The requirement for the gap between the base 135 and the workpiece 50.

[0062] As discussed above regarding conductive plate 137, conductive plates 437 and 420 may be formed of, for example, metal, but may also be formed of other conductive materials, or of conductive materials partially or completely coated with a protective (e.g., not necessarily conductive) material.

[0063] Although the concept of adjustment device 410 is illustrated by showing an adjustment device with a rod and nut, those skilled in the art will recognize that any type of mechanical or electromagnetic actuator can replace the illustrated combination of rod and nut. For example, gear mechanisms, spring-loaded devices, magnetic actuators, stepper motors, piezoelectric actuators, or other electromagnetic devices can be used instead. Those skilled in the art will readily recognize, upon reading and understanding this disclosure, alternatives, equivalents, modifications, and intermediate combinations that can be used as adjustment devices or actuators. In some embodiments, a plurality of hollow regions are formed on the lower surface of dielectric plate 469 to facilitate plasma ignition, as in combination with... Figure 1 The dielectric plate 169 is discussed.

[0064] Some embodiments utilize a single device 410 to adjust d1 across the waveguide cavity 467, while other embodiments use three devices 410 to adjust the plane formed by the movable conducting plate 420 relative to the plate 437. The connection of the device 410 to the movable conducting plate 420 can include a flexible material or joint that allows the movable conducting plate 420 to tilt relative to the device 410. Yet other embodiments can use more devices 410 with deformable conducting plates 420 to provide point-to-point control of d1 and the microwaves within the waveguide cavity 467 without regard to the planarity of the movable conducting plate 420 or the plate 437. Optionally, each device 410 is surrounded above the movable conducting plate 420 by a conductive bellows 413 that is mechanically and electrically coupled to the ceiling 415. The bellows 413 thus ensures that the movable conducting plate 420 is at the same electrical potential as the housing 405, and can contain any particles that can fall through the ceiling 415 and mate with the nut 411.

[0065] In the system 400, a small gap can be needed between the movable conducting plate 420 and the sides of the housing 405 to ensure that the conducting plate 420 can move freely. This can be done by allowing some microwaves to propagate via the gap without adversely affecting the propagation of the microwaves within the waveguide cavity 467, which can disrupt the eigenmode condition. As shown in Figure 4 The area shown as A in Figures 5A to 5D in the middle as an option to manage this effect. Figure 5A One of the RF gaskets or Figure 5B One of the RF chokes shown can be mounted around the movable conducting plate 420, and would thus exist in area A' as well as area A (e.g., A and A' are 180 degrees from each other around the perimeter of the housing 405).

[0066] Figure 5A An RF gasket 440 is shown inserted between the movable conducting plate 420 and the housing 405. The RF gasket 440 will generally be effective to reduce microwave leakage, but can scratch either or both of the movable conducting plate 420 and the housing 405. This can create metal particles that can undesirably affect the waveguide cavity 467 and move around it in response to the microwaves.

[0067] Figure 5B An RF choke 431 is shown that includes a conductive bracket 442 that is coupled to the movable conducting plate 420, and a dielectric material 444 that is held by the bracket 442 against the top surface of the movable conducting plate 420. Advantageously, the dielectric material 444 has a lateral dimension where ε1 is the dielectric constant of the material 444, λ is the wavelength of the microwaves, and m is any integer greater than zero.

[0068] Figure 5C An RF choke 432 is shown and a second dielectric material 445 is added, which includes the features of the RF choke 431. Advantageously, the dielectric material 444 has a dimension where ε2is the dielectric constant of the material 445, λ is the microwave wavelength, and p is any integer greater than zero. The fact that the dielectric fills the gap of the housing 405 should be taken into account; a soft and / or non-shedding dielectric such as polytetrafluoroethylene (e.g., Teflon®, ) or polyether ether ketone (PEEK)) can be used as the material 445.

[0069] Figure 5D An RF choke 433 is shown, which includes only a second dielectric material 445. In this embodiment, advantageously, the dielectric material 445 has a dimension where ε2is the dielectric constant of the material 445, λ is the microwave wavelength, and n is any odd integer greater than zero. L3is chosen to prevent electromagnetic waves from exciting in the dielectric-filled gap, thus reducing leakage of microwaves via the gap.

[0070] Certain embodiments herein can address situations such as signal generators, amplification electronics, and / or other components (e.g., the electronics group 225 of Figure 3 ) being unable to provide a sufficiently wide tuning range or a desirably large variety of resonant modes. One way to address this is to remove the electrically conductive plates that define the waveguide cavities (e.g., the cavities 167 or 467), so that the housing (e.g., the housing 405) defines a single cavity.

[0071] Figure 6 A schematic cross-sectional view showing a portion of a plasma processing system 470 that includes most of the features of the plasma processing system 400 Figure 4 . However, the system 470 does not include the electrically conductive plates at the bottom of the cavities 467. Because the components used in the system 470 are the same as those in the system 400, the same reference numerals are used for such components, but because the electrical behavior is different, some dimensions are labeled differently. d21 now represents the air gap height of the cavities 467, while d22 represents the thickness of the dielectric plate 469.

[0072] Electrically, the system 470 is a single cavity bounded by the housing 405 and the movable conducting plate 420 having a thickness dp. However, the thickness and dielectric constant of the dielectric plate 469 and the dimension d21 shown can still affect how microwaves propagate within the cavity, including affecting the eigenmode conditions. Thus, the mechanism for adjusting the height of the movable conducting plate 420, shown again here as adjustment device 410 and nut 411, is still a useful tool for tuning the microwave conditions within the cavity 467. Of course, one skilled in the art will appreciate that any type of mechanical or electromagnetic actuator can replace the shown rod and nut combination; all of the discussion regarding such features in connection with system 400 can be equivalently applied to system 470. With the height adjustment device in place, d21 can be considered a variable having a minimum of zero and a maximum of d21max, where the movable conducting plate 420 will abut the ceiling 415 (the lower surface of the movable conducting plate 420 will be the thickness dp of the movable plate below the ceiling 415). In practice, the zero and d21max limits can be further limited by the travel limits of the movable plate mechanism.

[0073] Advantageously, the system 470 can be adjusted to support at least one eigenmode within a portion of the housing 405, labeled as cavity 475. This allows for efficient down-coupling of the field to the lower surface of the dielectric plate 469, where the field will be coupled into the plasma 60. When d21 is at its minimum, the eigenmode will have a maximum frequency f 最大 ; when d21 is at its maximum, the eigenmode will have a minimum frequency f 最小 . Advantageously, the set of electronics driving the microwave input 466 supports all frequencies from f 最小 to f 最大 , so that a supported eigenmode can be set for any physical setting of the movable conducting plate 420. For any frequency available from the set of electronics, there will generally be one eigenmode position available for the movable conducting plate 420, but there can be more than one eigenmode position available if d21max is large enough.

[0074] Figure 7 is a schematic cross-sectional view of a portion of a plasma processing system 480 showing most of the features of the plasma processing system 470 including Figure 6 However, the system 480 does not include a movable ceiling. When the housing 405, the characteristics of the components in the housing 405, and the dimensions d21 and d22 are known and / or controllable, it can be possible to provide a monolithic housing with a dielectric plate 469 having a vacuum seal therein, where the dimensions are adjusted so that the eigenmodes are supported by the cavity 485, which is similar to Figure 6The system 470 has a cavity 475. Furthermore, if the electronics group driving the microwave input 466 supports frequency adjustment, it is possible to tune the microwave frequency to support the intrinsic modes within the cavity 485; however, d21 and d22 are effectively fixed. Alternatively, if d21 is adjusted before the sealed housing 405 (e.g., by utilizing a temporary mechanism for adjusting the height of the dielectric plate 469 to characterize the energized system 480, which can later be withdrawn), a more compact completed system 480 can be provided using fewer moving parts or adjustments. Similar to... Figure 4 For system 400, considerations such as size, weight, cost, and materials to be used can be used to select dimensions d21 and d22. d22 especially needs to be thick enough to withstand the atmospheric pressure on dielectric plate 469 when the evacuation process chamber 430 is evacuated, but when d22 is very high, dielectric plate 469 can become heavy and expensive.

[0075] Figure 8 It shows including Figure 7 A schematic cross-sectional view of a portion of a plasma processing system 490, showing most of the features of the plasma processing system 480. However, system 490 is powered by a top-injected microwave input 468, rather than by... Figure 4 , Figure 6 and Figure 7 The side-injected microwave input 466 shown in systems 400, 470, and 480 is powered. While other embodiments may theoretically use top-injected microwave inputs, such as input 468, integrating such inputs with the movable board of such embodiments can be difficult. Like system 480, system 490 in a compact form can be provided, particularly in applications where integrating one or more side-injected microwave inputs 466 is problematic.

[0076] In one embodiment, d21 can be further modified by reducing it to zero. Figure 7 and Figure 8 The design. Figure 9 It shows that it includes and Figure 7 A schematic cross-sectional view of a portion of a plasma processing system 495, featuring similar characteristics to the plasma processing system 480, where d21 is set to zero, i.e., cavity 467 is eliminated. Like systems 480 and 490, system 495 can be provided in a compact form. In an alternative embodiment of system 495, a side-injected microwave input 466 is available. Figure 8 The top of the system 490 is injected with microwave input 468 instead.

[0077] Figure 10 It shows including Figure 4 Plasma processing system 400 and Figure 7A schematic cross-sectional view of a portion of a plasma processing system 500, illustrating most of the features and operating concepts of the processing system 480. System 500 introduces a gap 510, similar to dielectric plate 469, between plate 437 and dielectric plate 520. Dielectric plate 520 encloses process chamber 430 and is separated from gap 510 and cavity 467, such that these areas are not evacuated when process chamber 430 is evacuated. Cavity 505 may be defined to include gap 510 and dielectric plate 520. Then, in a manner similar to... Figure 7 In the manner of processing system 480, if the electronic equipment group driving microwave input 466 supports frequency adjustment, the microwave frequency may be tuned to support the eigenmode within cavity 505; however, d21 and d22 are in fact fixed. That is, frequency adjustment can be used to tune cavity 505 to support another eigenmode, while movable conductive plate 420 can be used to tune cavity 467 to support another possible similar eigenmode (e.g., if TE...). 112 If excited within cavity 505, then TE is advantageous. 111 It can be excited within cavity 467.

[0078] Figure 11 To show including Figure 10 A schematic cross-sectional view of a portion of a plasma processing system 550, illustrating most features and operational concepts of the plasma processing system 500. System 550 incorporates an adjustable dielectric layer 530 with a controllable height; for example, the dielectric layer may be a liquid dielectric layer (or a capsule filled with a liquid dielectric), which does not absorb significant energy at microwave frequencies. A suitable material for the adjustable dielectric layer 530 is perfluoropolyether (PFPE), having a dielectric constant ε = 1.94 and a loss tangent tanδ = 2 × 10⁻⁶. -4 Cavity 505 may be defined as including gap 510, adjustable dielectric layer 530, and dielectric plate 520. The height d21 within cavity 505 may be defined as the sum of the electrical lengths of the height d211 of gap 510 and the height d212 of adjustable dielectric layer 530, i.e. Where ε 液体The dielectric constant of the dielectric layer 530. The controller 540 can increase or remove portions of the liquid dielectric via the fluid connection, and thus the mechanical adjustment can adjust the dielectric layer 530 to establish or maintain the eigenmode condition within the cavity 505. This provides an additional degree of freedom for optimizing the operation of the system 550, as the movable conductive plate 420 can be used to optimize the cavity 467, and the adjustable dielectric layer 530 can be used to optimize the cavity 505, without needing to tune the microwave frequency supplied via the microwave input 466. Thus, if the set of electronics powering the microwave input 466 is tunable, the tunability can be preserved to optimize other features (e.g., establishing or maintaining the eigenmode condition within the process chamber 430). Alternatively, a set of electronics that is not tunable can be used to reduce cost.

[0079] Figure 12 A schematic cross-sectional view of a portion of a plasma processing system 560 to illustrate most of the features and operational concepts of the plasma processing system 500 including Figure 10 The system 560 introduces an upper housing 515 including the microwave cavity 467 and a lower housing 517 including the process chamber 430. The relative position of the upper housing 515 and the lower housing 517 is adjusted via an actuator 570, which can be mechanical, magnetic, electromagnetic, piezoelectric, or the like, as with the adjustment device 410. Adjusting the relative position of the upper housing 515 and the lower housing 517 causes the height of the gap 510 to increase or decrease, respectively. The cavity 507 can be defined to include the gap 510 and the dielectric plate 520, and thus extension or contraction of the actuator 570 can tune the cavity 507 in a manner similar to how the adjustable dielectric layer 530 tunes the cavity 505 of the system 550. Figure 11 ) of the system 550. Figure 5A One of the RF gaskets or Figure 5B One of the RF chokes shown can be mounted at the interface between the upper housing 515 and the lower housing 517, and thus would be present in region B’ as well as region B (e.g., B and B’ are 180 degrees apart around the periphery of the housings 515, 517).

[0080] The methods now discussed provide a means to mitigate the local effects of non-uniformities during processing. Dimensional variations, material non-uniformities, equipment asymmetries, and the like can cause certain regions of the process chamber to have more intense plasma action than other regions. These effects can be localized or generalized within the system; that is, some process non-uniformities can affect individual locations that are difficult to predict in advance, while other non-uniformities can be predictably in a radial or azimuthal form with respect to the cylindrical waveguide 210. When these effects occur, the corresponding regions of the workpiece 50 being processed by the plasma can be processed non-uniformly.

[0081] Figure 13An exemplary pattern of process variation on a workpiece 50 (e.g., a semiconductor wafer) is shown. Due to one or more subtle variations in parameters such as gas distribution uniformity, electric field uniformity, variations in process chamber materials, and / or the presence of asymmetric items (such as sensors, ports, workpiece handling equipment, etc. associated with the process chamber), region 580 is treated to have a nominal result, while region 588 is treated to have a poorer result. The significant performance difference between regions 580 and 588 is for purposes of illustration only. That is, region 588 can accept processing (e.g., etching or deposition) that can differ by only a few percent from the processing accepted in region 580, but it can still be desirable to reduce the percent as much as possible.

[0082] In embodiments, the effect of region 588 can be achieved via a purely electrical device, with workpiece 50 itself remaining stationary. Figure 14 The effect of a slow rotating wave process on the processing of workpiece 50 is shown. The terms "slow rotating" or "slowly rotating" are used herein to mean a wave pattern that changes over time at a rate or frequency that is much lower than the propagation frequency of the electromagnetic radiation (e.g., no more than 1 / 1000 th ) of the nominal microwave frequency herein can be about 2.5 GHz, but the slow rotating mode will have a frequency < 1 MHz, and typically < 10 KHz.

[0083] As shown, the ghosted outline of region 588 (labeled 588') can be made to rotate in a counter-clockwise direction (and can similarly be made to rotate in a clockwise direction) over workpiece 50. Rotating region 588' can be seen as smoothing or erasing the effect that was initially present in region 588, such that no portion of workpiece 50 is subjected to the same degree of influence as the original region 588. In the example shown, region 588' does not rotate over the inner and outer regions of workpiece 50, so these regions are still labeled as region 580'. A small portion of region 588' rotates over band 582 near the inner and outer regions of the workpiece, while the majority of region 588' rotates over band 584 between bands 582. (It should be understood that workpiece 50 is depicted as having bands for purposes of illustration only; the processing effect will fade gradually into one another, rather than forming a step function change at the edges of bands 582 and / or 584.) Thus, the process effect present in original region 588 can be spread over a larger area and will be reduced across bands 582 and 584, as compared to the concentration of such process effect in original region 588.

[0084] Ω is chosen so that the numerous field rotations that occur during the plasma processing allow for the rotation of corresponding plasma inhomogeneities, thus smoothing out the effects of "hot" or "cold" treatment points (e.g., region 588) caused by inhomogeneities on the workpiece. Ω can also be empirically adjusted by the user based on measured process uniformity results.

[0085] The effect of the rotating wave pattern within the waveguide cavity on the plasma generated in adjacent process chambers can also vary depending on the rotational speed. When Ω is below approximately 100 Hz, plasma ignition can immediately follow the field rotation. Therefore, both the field and the plasma rotate at the rotational frequency Ω. When Ω is above approximately 1000 Hz, the plasma cannot follow the field but is sensitive to the overall distribution of the electric field intensity, resulting in a radially symmetrical uniform plasma distribution. At intermediate values ​​between approximately 100 Hz and 1000 Hz, the effect is a mixture of rotating and radially symmetrical plasma distributions. Interactions can also exist between local plasma effects caused by random factors and the rotational frequency, such that adjusting the rotational frequency Ω can sometimes increase or decrease local processing non-uniformity. These interactions can be localized by characterizing process performance at various rotational frequencies Ω and selecting the Ω value that provides optimal uniformity. Advantageously, these effects can be achieved purely electronically, for example by simply inputting the desired value of the appropriate microwave signal by the user and having the controller of the process equipment (e.g., signal generator 215) calculate the appropriate microwave signal according to the following discussion. That is, no mechanical equipment modification is required.

[0086] Currently using Figure 3 The system 300 considers the configuration of any of the aforementioned systems 200, 300, 400, 470, 480, 495, 500, 550, and 560 within the context of the coordinate system shown. In some embodiments discussed, this is for generalized TE and TM modes (e.g., TE...). mnl / TM mnl It provides a slow wave rotation with a rotation angular frequency Ω (Ω / 2π~0.1-1000Hz) as a means to mitigate the local effects of non-uniformity during processing.

[0087] Assume microwaves travel from... Figure 3 The microwave inputs P and Q are injected into the system 300, where the time-varying amplitudes are related to cos(Ωt) and Proportional. Here The time phase delay is determined later, and t represents time. TE in a cylindrical cavity excited by injection from microwave input P. mnl / TM mnl The pattern can be represented as:

[0088] A p= a cos Ωt [cos (ωt - mθ) + cos (ωt + mθ)] Equation (1)

[0089] where terms depending on the radial (r) and axial (z) coordinates are included in the coefficient a, and m is a positive integer.

[0090] Equation (1) can also be written in several forms:

[0091]

[0092] In the same way, the TE mnl / TM mnl mode excited by the injection from the microwave input Q can be described in complex form as:

[0093]

[0094] Rewriting Equations (2) and (3),

[0095]

[0096]

[0097] Thus, the wave obtained in the cavity can be given by:

[0098]

[0099] In order to provide a counterclockwise rotation, the following conditions must be satisfied:

[0100]

[0101]

[0102] Or, in the same way,

[0103]

[0104]

[0105] where r and s are arbitrary integers.

[0106] Solving Equations (9) and (10) simultaneously, the conditions for a counterclockwise rotation can be expressed as:

[0107]

[0108]

[0109] In the same way, for a clockwise rotation, Equations (7) and (8) become:

[0110]

[0111]

[0112] and equations (9) and (10) become:

[0113]

[0114]

[0115] Solving equations (15) and (16) simultaneously, the condition for clockwise rotation can be expressed as:

[0116]

[0117]

[0118] Comparing equations (11) and (12) with (17) and (18), the angle θ q has the same form, while the time phase delay between counterclockwise and clockwise rotation (φ and ) differs by π.

[0119] Explicitly, equations (11) and (12), (17) and (18) can be solved as:

[0120] First case: r = 1, s = 0.

[0121]

[0122]

[0123]

[0124] Second case: r = 2, s = 0.

[0125]

[0126]

[0127]

[0128] Returning to the case of counterclockwise rotation, the resulting field of equation (6) can be expressed in complex form as:

[0129] A s = ae j(Ωt-mθ) [e jωt + e -jωt ] = 2e j(Ωt-mθ) cos(ωt) Equations (21) and (22) can be expressed in real form as:

[0130] As = 2a cos(Ωt - mθ) cos(ωt) Equation (22)

[0131] This means that the resulting wave has an angular frequency It rotates slowly in the counter-clockwise direction.

[0132] Equations (4) and (5) can be expressed under counter-clockwise rotation as:

[0133] A p = 2a e jΩt cos(mθ) cos(ωt)

[0134] A q = -2ja e jΩt sin(mθ) cos(ωt) Equation (23)

[0135] In real form:

[0136] A p = 2a cos(Ωt) cos(mθ) cos(ωt)

[0137] A q = 2a sin(Ωt) sin(mθ) cos(ωt) Equation (24)

[0138] To derive the input waveforms at ports P and Q, one must substitute the coordinates of P and Q into θ as:

[0139] A p (θ = θ p ) = 2a cos(Ωt) cos(m θ p) cos(ωt)

[0140] A q (θ = θ q ) = 2a sin(Ωt) sin(mθ q ) cos(ωt) Equation (25-1)

[0141] Equation (25-1) provides the general form of the input waveforms at ports P and Q in the case of (counter-clockwise rotation).

[0142] In the case of Equation (20), i.e., θ p = 0, and Equation (7): Equation (25-1) becomes:

[0143] A p (θ = θ p ) = 2a cos(Ωt) cos(ωt)

[0144] Aq (θ = θ q ) = -2a sin(Ωt)cos(ωt) Equation (25-2)

[0145] Equation (25-2) provides the input waveform at ports P and Q in the case of (counterclockwise rotation) and .

[0146] For clockwise rotation, the equations corresponding to Equations (21) through (25-2) are expressed as follows, respectively:

[0147] A s = ae j(Ωt+mθ) [e jωt + e -jωt ] = 2e j(Ωt+mθ) cos(ωt) Equation (26)

[0148] A s = 2a cos(Ωt+mθ)cos(ωt) Equation (27)

[0149] A p = 2ae jΩt cos(mθ)cos(ωt)

[0150] A q = 2ja e jΩt sin(mθ)cos(ωt) Equation (28)

[0152] A p = 2a cos(Ωt)cos(mθ)cos(ωt)

[0153] A q = -2a sin(Ωt)sin(mθ)cos(ωt) Equation (29)

[0154] A p (θ = θ p ) = 2a cos(Ωt)cosmθ p )cos(ωt)

[0155] A q (θ = θ q ) = -2a sin(Ωt)sin(mθ q )cos(ωt) Equation (30-1)

[0156] Equation (30-1) provides the general form of the input waveform at ports P and Q in the case of (clockwise rotation).

[0157] In the case of equation (20), i.e., θ p = 0, and equation (7):

[0158] A p (θ = θ p ) = 2a cos(Ωt) cos(ωt)

[0159] A q (θ = θ q ) = 2a sin(Ωt) cos(ωt) equation (30-2)

[0160] Equation (30-2) provides the input waveforms at ports P and Q in the case of clockwise rotation) and .

[0161] The above derivations can be used as a basis for providing input to the set of electronic devices such that a given wave pattern within the microwave cavity can be rotated over time. For example, it can be desirable to transmit microwaves of frequency ω and have the resulting wave pattern rotate at an angular frequency Ω. Referring to Figure 3 , the relative locations P and Q from which electromagnetic radiation is delivered from the set of electronic devices 225(1) and 225(2) are known. The signal generator 215 can be preprogrammed to select ω and / or Ω, or enter ω and / or Ω as user preferences using the user input device 314. With all of these parameters known, if the rotation should be in the clockwise direction, then the signal generator 215 calculates A p and A q according to equation 25-2, or if the rotation should be in the counterclockwise direction, then A p and A q are calculated according to equation 30-2, and the input signals 220(1) and 220(2) are provided according to the calculated A p and A q .

[0162] In contrast to the vertical eigenmodes discussed above, certain uniformity issues can also be addressed by exciting different radial eigenmodes within the microwave cavity to alter the radial plasma characteristics. For example, assume that a region 588 is characterized that shows the presence of a region like Figure 13 . The region 588 is not at the center within the workpiece 50, but rather somewhere between the center and the edge of the workpiece 50. It is difficult to remove the region 588 caused by the non-uniformity with a conventional microwave source.

[0163] A new proposal to remove the non-uniformity is to use an electric field 590 as shown in Figure 15 that has an asymmetric high edge profile. The profile of the plasma 60 is determined by the square of the electric field at a given location. As Figure 16 ​As shown, Figure 15 The field shown can be generated by the first TE mode (such as TE). 111 Mode 591) is superimposed on second TE modes of different orders (such as TE) 011 This is generated in mode 593. Only the electric field E is considered. θ The azimuth component, because TE 011 The radial component of mode 593 is always zero. This can lead to TE. 111 Mode 591 and TE 011 The resonant frequency of mode 593 is slightly different. For example, for a specific cavity with a diameter of approximately 400 mm, For the same cavity Thus, as time passes, the shape of the obtained field 590 ( Figure 15 This will change. To avoid this, the electromagnetic radiation frequency ω 111 and ω 011 The phase difference between them must be reset to zero periodically.

[0164] As discussed above, different orders of TE modes can also be supplied using slow rotation. For example, for TE... 111 The input power of mode 591 can be expressed in the following form at points P and Q ( Figure 3 )injection,

[0165] A p =2a cos[Ω(t)t]cosω 111 t

[0166] A q = 2a sin[Ω(t)t]cosω 111 Equation (31)

[0167] This produces a counter-clockwise rotation. The time-dependent slow rotational angular frequency Ω can be distributed to mitigate the non-uniformity. However, for TE... 011 The power injection in mode 593 has degrees of freedom because TE 011 Mode 593 is azimuthally symmetrical. (TE) 011 Mode 593 provides a representative form of input power that will use the following form,

[0168] B p =2b cosω 011 t

[0169] B q =2b cosω 011 Equation (32)

[0170] The time-dependent allocation of Ω can be implemented by the signal generator 215. Typically, the different order modes (such as TE 11X and TE 01X , where x = 1 or 2) differ in frequency by about 30 to 140 MHz depending on the size of the chamber being powered. A computer- processable hardware such as a microprocessor or FPGA can be implemented within the signal generator 215 to determine and reset the time phase of these modes relative to each other.

[0171] The strategy just discussed above can also be applied in cases where equipment capabilities or other process limitations cause simple radial process non-uniformities. For example, Figure 21A The workpiece 50 is shown after processing with a nominal plasma process that produces different results in the outer region 710 and the inner region 720. In the case of an etch process, region 720 can experience a nominal etch while region 710 experiences a reduced etch, but this scenario can also be reversed or applied to another process type (e.g., a deposition process). If the nominal process is provided with an etch time ti using a plasma excited by TE 011 modes. An additional etch time t2 can be added to the process where the etch is provided with a plasma excited by high edge modes such as TE 211 . As with the process strategy above, this is simply implemented via electronic means, i.e., the signal generator 215 can provide the appropriate frequency, phase, and / or amplitude changes to provide TE 011 , TE 211 , and / or other modes. No mechanical equipment changes are required. Figure 21B A procedure implementing this strategy is shown schematically where a first process segment 730 (e.g., a nominal etch process using TE 011 modes) is conducted at nominal power until time ti, and a second process segment 740 (e.g., a custom high edge etch process using TE 211 modes and / or other modes) continues for an elapsed time increment t2. The plasma power is shown reduced in segment 740 compared to segment 730, but this need not be the case, the power of segment 740 can be equal to or even greater than the power of segment 730. Further process segments can also be added. One of ordinary skill in the art will readily recognize alternatives, equivalents, modifications, additions, and intermediate combinations of this technique.

[0172] Chamber geometry and / or configuration can also make implementation of slow rotation and / or multiple order TE modes challenging, particularly when the same frequency must be resonated in two different cavities (e.g., as in Figure 10 , Figure 11 and Figure 12One approach to address this challenge is to design one or both of the resonant cavities with a low quality factor, such that the resonant peaks are less pronounced in amplitude, but wider in frequency.

[0173] Figure 17 is a flowchart of a method 600 that generates plasma for processing a workpiece. The method 600 can be implemented using one or more of the systems 100, 400, 500, 550, and 560 disclosed herein. A first step 602 of the method 600 introduces one or more process gases into a process chamber (e.g., the process chamber 130 or 430). The process chamber is at least partially sealed with a dielectric plate (e.g., the dielectric plate 169, 469, 520) that is capable of supporting a differential pressure corresponding to an evacuation of the process chamber. A second step 604 of the method 600 propagates electromagnetic radiation (e.g., electromagnetic radiation from the set of electronic devices 225(2), 225(2)) into a waveguide cavity (e.g., the cavity 167 or 467) disposed adjacent to the process chamber. The waveguide cavity is at least partially bounded by a first electrically conductive plate (e.g., the electrically conductive plate 420) that faces the process chamber and is disposed across the waveguide cavity from the process chamber. The cavity is also at least partially bounded by a second electrically conductive plate (e.g., the plate 437) disposed between the waveguide cavity and the dielectric plate. The second electrically conductive plate forms a plurality of apertures (e.g., the slots 168) that allow the electromagnetic radiation to propagate into the chamber via the second electrically conductive plate, via the dielectric plate. A third step 606 ignites a plasma from the process gases. A fourth step 608 sustains the plasma with power supplied by the electromagnetic radiation propagating into the process chamber via the apertures of the second electrically conductive plate.

[0174] The method 600 can be varied to use any of the equipment variants disclosed herein, where the equipment variants are compatible with the listed steps 602-608. One of ordinary skill in the art, upon reading and understanding this disclosure, based on the concepts and equipment capabilities disclosed herein, will not only be able to practice the specifically listed method 600, but will also readily recognize alternatives, equivalents, modifications, augmentations, and intermediate combinations of the disclosed steps.

[0175] Figure 18For the flowchart of method 610, which provides electromagnetic radiation in a process chamber for powering a plasma. Method 610 can be implemented using one or more of the systems 100, 400, 470, 480, 490, 500, 550, and 560 disclosed herein. The first step 612 of method 600 introduces one or more process gases into a process chamber (e.g., process chamber 130 or 430). The second step 614 of method 610 propagates electromagnetic radiation (e.g., electromagnetic radiation from the set of electron devices 225(2), 225(2)) from at least two locations P and Q Figure 4 ) into a waveguide cavity (e.g., cavity 167 or 467) disposed adjacent to the process chamber. The waveguide cavity is separated from the process chamber (e.g., by a dielectric plate, such as dielectric plate 169, 469, 520) such that the process chamber can be evacuated without evacuating the waveguide cavity, while the electromagnetic radiation within the waveguide cavity can still be propagated into the process chamber. Locations P and Q are disposed at respective angles Θ p and Θ q around the perimeter of the waveguide cavity Figure 4 , and the electromagnetic radiation is provided in the waveguide cavity at a microwave frequency ω and a rotation frequency Ω (Equation 1-32). The third step 616 ignites a plasma from the process gas. The fourth step 618 sustains the plasma with power supplied from the electromagnetic radiation propagated from the waveguide into the process chamber.

[0176] Method 610 can be varied to use any of the equipment variations disclosed herein, where the equipment variations are compatible with the listed steps 612-618. One of ordinary skill in the art, upon reading and understanding this disclosure, based on the concepts and equipment capabilities disclosed herein, will not only be able to practice the specifically listed method 610, but will also readily recognize alternatives, equivalents, modifications, augmentations, and intermediate combinations of the disclosed steps.

[0177] Figure 19For the flowchart of method 620 for plasma processing in a process chamber. Method 620 can be implemented using one or more of the systems 100, 400, 470, 480, 490, 500, 550, and 560 disclosed herein. First step 622 of method 620 introduces one or more process gases into a process chamber (e.g., process chamber 130 or 430). The process chamber is disposed adjacent to a waveguide cavity (e.g., cavity 167 or 467), and the waveguide cavity is separated from the process chamber without blocking propagation of electromagnetic radiation within the waveguide cavity into the process chamber (e.g., through a dielectric plate, such as dielectric plate 169, 469, 520). Second step 624 of method 620 propagates electromagnetic radiation into the waveguide cavity (e.g., from electronic device set 225(2), 225(2)). The electromagnetic radiation is provided at a microwave frequency ω. A first portion of the power supplied within the waveguide cavity is supplied by a portion of the electromagnetic radiation resonating in a first TE mode within the waveguide cavity, and a second portion of the power supplied within the waveguide cavity is supplied by a portion of the electromagnetic radiation resonating in a second TE mode within the waveguide cavity Figure 15 , Figure 16 ). Third step 626 ignites a plasma from the process gas. Fourth step 628 sustains the plasma with power supplied from the electromagnetic radiation propagated from the waveguide into the process chamber.

[0178] Method 620 can be varied to use any of the equipment variations disclosed herein, where the equipment variations are compatible with the listed steps 622-628. One of ordinary skill in the art, upon reading and understanding this disclosure, based on the concepts and equipment capabilities disclosed herein, will recognize not only the specific method 620 listed, but also readily recognize alternatives, equivalents, modifications, augmentations, and intermediate combinations of the disclosed steps.

[0179] Figure 20For the flowchart of method 630 for processing a workpiece in a process chamber. The method 630 can be implemented using one or more of the systems 100, 400, 470, 480, 490, 500, 550, and 560 disclosed herein. The first step 632 of the method 630 places a workpiece in a process chamber (e.g., the process chamber 130 or 430). The process chamber is disposed adjacent to a waveguide cavity (e.g., the cavity 167 or 467), and the waveguide cavity is separated from the process chamber without blocking the propagation of electromagnetic radiation within the waveguide cavity into the process chamber. The second step 634 of the method 630 processes the workpiece in the process chamber with a first plasma (e.g., the plasma 60). Step 634 includes introducing one or more process gases into the process chamber, propagating electromagnetic radiation into the waveguide cavity (e.g., from the electronic device set 225(2), 225(2)), igniting a plasma from the process gases, and sustaining the plasma with power supplied from the electromagnetic radiation propagating from the waveguide cavity into the process chamber. At least a portion of the power for the first plasma is supplied by electromagnetic radiation resonating within the waveguide cavity in a first TE mode. The third step 636 of the method 630 processes the workpiece in the process chamber with a second plasma (e.g., the plasma 60). Step 636 includes introducing one or more process gases into the process chamber, propagating electromagnetic radiation into the waveguide cavity (e.g., from the electronic device set 225(2), 225(2)), igniting a plasma from the process gases, and sustaining the plasma with power supplied from the electromagnetic radiation propagating from the waveguide cavity into the process chamber. At least a portion of the power for the first plasma is supplied by electromagnetic radiation resonating within the waveguide cavity in a second TE mode. The order of the first TE mode is different than the order of the second TE mode.

[0180] The method 630 can be varied to use any of the equipment variations disclosed herein, where the equipment variations are compatible with the listed steps 632-636. One of ordinary skill in the art, having the benefit of the disclosures herein, and based on the concepts and capabilities of the equipment disclosed herein, will readily recognize alternatives, equivalents, modifications, additions, and intermediate combinations of the disclosed steps in addition to the specifically recited method 630, upon a reading and understanding of this disclosure.

[0181] Having described several embodiments, one skilled in the art will recognize that the embodiments of this application can comprise any combination of the features recited above and those described in the detailed description, although not all of the features are necessarily required in all embodiments. Therefore, one skilled in the art will recognize that still other variations are within the spirit of the present application. Accordingly, the application is not to be restricted except in the spirit of the claims.

[0182] It should be understood that where a numerical range is provided, it is specifically intended that every number within that range, and any sub-range of any of the numbers, is incorporated in the range, specifically unless the context clearly indicates otherwise. Any smaller range that falls within the recited range is also contemplated. The upper and lower limits of these smaller ranges can independently be included or excluded in the smaller ranges, and the endpoint, neither, or both of the limits of the smaller ranges are also included in the smaller ranges, subject to any specifically excluded limit in the smaller range. Where the range includes one or both of the limits, ranges excluding either or both of those included limits are also included.

[0183] As used herein and in the appended claims, the singular forms "a," "an," and "the" include plural reference unless the context clearly dictates otherwise. Thus, for example, a reference to "a process" includes a plurality of such processes, and a reference to "the electrode" includes reference to one or more electrodes and equivalents thereof known to those skilled in the art. In addition, the words "comprise," "comprising," "include," "including," and "includes," when used in this specification and in the following claims, are intended to specify the presence of stated features, integers, components, or steps, but they do not preclude the presence or addition of one or more other features, integers, components, steps, acts, or groups.

Claims

1. A plasma generation system, comprising: a housing defining a process chamber and a waveguide cavity, wherein the waveguide cavity is disposed adjacent to the process chamber and is configured to propagate electromagnetic radiation from the waveguide cavity into the process chamber; a first electrically conductive plate positioned within the housing and at least partially defining the waveguide cavity; a second electrically conductive plate positioned within the housing and at least partially defining the waveguide cavity to influence a mode of electromagnetic radiation propagating within the waveguide cavity; one or more groups of electronic devices configured to transmit the electromagnetic radiation into the waveguide cavity to generate a plasma from at least one process gas delivered within the process chamber; a dielectric plate, wherein the first electrically conductive plate is positioned within the housing in parallel with the dielectric plate with a gap between the second electrically conductive plate and the dielectric plate; an adjustable dielectric layer comprising a liquid dielectric disposed within the gap; and a controller configured to add or remove portions of the liquid dielectric.

2. The system of claim 1, wherein each given group of the one or more groups of electronic devices matches a drive impedance of that given group of the one or more groups of electronic devices to an impedance presented by the waveguide cavity to that given group of the groups of electronic devices.

3. The system of claim 1, further comprising a signal generator configured to: provide a first microwave signal to a first group of the one or more groups of electronic devices, and provide a second microwave signal to a second group of the one or more groups of electronic devices; and wherein: the first and second microwave signals have a common frequency; and the first and second groups of electronic devices are configured to amplify the first and second microwave signals, respectively, to provide the electromagnetic radiation.

4. The system of claim 3, further comprising a dielectric plate enclosing the process chamber separate from the waveguide cavity such that the waveguide cavity is not evacuated when the process chamber is evacuated; and wherein the signal generator is configured to adjust the common frequency to support an eigenmode within the dielectric plate.

5. The system of claim 3, further comprising: at least two monitor antennas; and a signal controller configured to: receive analog signals from the at least two monitor antennas; and transmit digital correction signals to the signal generator based at least on the analog signals from the at least two monitor antennas; wherein the signal generator is configured to adjust at least one of a phase and an amplitude of the first and second microwave signals in response to the digital correction signals.

6. The system of claim 5, wherein the first group of electronic devices comprises: a tuner configured to match a drive impedance of the first group of electronic devices to an impedance presented by the waveguide cavity; a dummy load; and a circulator configured to shunt any power reflected from the waveguide cavity back to the first group of electronic devices into the dummy load. ​ ​ ​ ​ wherein the signal generator is configured to adjust at least one of the phase and the amplitude of the first and second microwave signals, and the tuner is configured to match the drive impedance to each other simultaneously.

7. The system of claim 1, wherein the first electrically conductive plate defines a plurality of apertures to allow the electromagnetic radiation to propagate into the process chamber.

8. The system of claim 7, further comprising a dielectric plate enclosing the process chamber while being separated from the waveguide cavity such that the waveguide cavity is not evacuated when the process chamber is evacuated; and wherein the first electrically conductive plate abuts and is in direct contact with the dielectric plate.

9. The system of claim 7, wherein the dielectric plate encloses the process chamber while being separated from the waveguide cavity such that the process chamber can be evacuated without evacuating the waveguide cavity; the adjustable dielectric layer is configured to adjust a condition of eigenmodes within a cavity formed by the gap, the adjustable dielectric layer, and the dielectric plate; and the controller is configured to add or remove portions of the liquid dielectric to adjust a thickness of the adjustable dielectric layer.

10. The system of claim 7, wherein when the position of the second electrically conductive plate is adjusted to an eigenmode position and the one or more electronic device groups transmit the electromagnetic radiation into the waveguide cavity, the waveguide cavity is configured to support an eigenmode.

11. The system of claim 7, further comprising: one or more adjustment devices coupled with the second electrically conductive plate and the housing, wherein the one or more adjustment devices are operable to adjust at least a position of the second electrically conductive plate over a range of positions.

12. The system of claim 11, wherein the one or more adjustment devices consist of three adjustment devices such that adjusting the three adjustment devices adjusts a position of the first electrically conductive plate over the range of positions and an inclination of the second electrically conductive plate relative to the housing.

13. The system of claim 12, further comprising one or more electrically conductive bellows corresponding one-to-one with the one or more adjustment devices, wherein each of the one or more electrically conductive bellows surrounds its corresponding adjustment device and electrically connects the second electrically conductive plate with the housing.

14. The system of claim 1, wherein each of the one or more adjustment devices comprises a threaded rod, a gear device, a magnetic actuator, a stepper motor, or a piezoelectric actuator coupled with the second electrically conductive plate.

15. The system of claim 1, further comprising: an RF choke coupled with the second electrically conductive plate and configured to reduce microwave leakage via a gap between the second electrically conductive plate and the housing, wherein the RF choke comprises: an electrically conductive brace disposed on a side of the second electrically conductive plate facing away from the first electrically conductive plate around an outer periphery of the second electrically conductive plate; and a dielectric material secured by the electrically conductive support against the second electrically conductive plate, wherein the dielectric material has a lateral dimension where ε1is the dielectric constant of the dielectric material, λ is the wavelength of the electromagnetic radiation, and m is any integer greater than zero.

16. A plasma generation system, comprising: a housing defining a process chamber and a waveguide cavity, wherein the waveguide cavity is disposed adjacent to the process chamber and configured to propagate electromagnetic radiation from the waveguide cavity into the process chamber, the housing comprising an upper housing and a lower housing; a first electrically conductive plate positioned within the housing and at least partially defining the waveguide cavity; a second electrically conductive plate positioned within the housing and at least partially defining the waveguide cavity to influence a mode of electromagnetic radiation propagating within the waveguide cavity; one or more groups of electronic devices configured to send the electromagnetic radiation into the waveguide cavity to generate a plasma from at least one process gas delivered within the process chamber; a dielectric plate enclosing the process chamber separate from the waveguide cavity such that the process chamber can be evacuated without evacuating the waveguide cavity; and an actuator operable to adjust a position of the upper housing relative to the lower housing; wherein the position of the upper housing relative to the lower housing determines a width of a gap between the first electrically conductive plate and the dielectric plate.

17. A plasma processing system, comprising: a housing defining a process chamber and a waveguide cavity, wherein the waveguide cavity is disposed adjacent to the process chamber and configured to propagate electromagnetic radiation from the waveguide cavity into the process chamber; a first electrically conductive plate positioned within the housing and at least partially defining the waveguide cavity; one or more process gas supplies configured to introduce one or more process gases into the process chamber; a second electrically conductive plate positioned within the housing and at least partially defining the waveguide cavity; one or more adjustment devices coupled with the second electrically conductive plate and the housing, wherein the one or more adjustment devices are operable to adjust a distance between the first electrically conductive plate and the second electrically conductive plate to influence a mode of electromagnetic radiation propagating within the waveguide cavity; one or more groups of electronic devices operable to send the electromagnetic radiation into the waveguide cavity, wherein each given group of the one or more groups of electronic devices is configured to match a drive impedance of that given group of the one or more groups of electronic devices to an impedance presented by the waveguide cavity to that given group of the one or more groups of electronic devices to generate a plasma from the one or more process gases; a dielectric plate, wherein the first electrically conductive plate is positioned within the housing parallel to the dielectric plate with a gap between the second electrically conductive plate and the dielectric plate; an adjustable dielectric layer comprising a liquid dielectric disposed within the gap; and a controller configured to add or remove portions of the liquid dielectric.

18. The plasma processing system of claim 17, further comprising: ​ a signal generator configured to provide at least a first microwave signal to a first set of electronic devices of the one or more sets of electronic devices and a second microwave signal to a second set of electronic devices of the one or more sets of electronic devices, wherein: the signal generator is configured to provide the first and second microwave signals at a common frequency; and the first and second sets of electronic devices are configured to amplify the first and second microwave signals, respectively, to provide the electromagnetic radiation.

19. The plasma processing system of claim 17, wherein the waveguide cavity is defined by: a dielectric plate enclosing the process chamber while being spaced apart from the waveguide cavity such that the waveguide cavity is not evacuated when the process chamber is evacuated; wherein the waveguide cavity is capable of supporting an eigenmode when the position of the second electrically conductive plate is adjusted to an eigenmode position.

20. The plasma processing system of claim 19, further comprising: one or more adjustment devices coupled with the second electrically conductive plate and the housing, wherein the one or more adjustment devices are operable to adjust at least the position of the second electrically conductive plate over a range of positions, the range of positions including the eigenmode position.

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