Apparatus and method for manipulating power at an edge ring in a plasma processing device

Abstract

Methods and apparatuses for processing a substrate positioned on a substrate support assembly are provided. For example, a substrate support assembly includes an electrostatic chuck having one or more chucking electrodes embedded therein for chucking a substrate to a substrate support surface of the electrostatic chuck, an edge ring disposed on the electrostatic chuck and surrounding the substrate support surface, two or more radio frequency (RF) power sources coupled to the edge ring, and at least one of a baseplate disposed below the electrostatic chuck or an electrode disposed in the electrostatic chuck, a matching network coupling the edge ring to the two or more RF power sources, and an RF circuit coupling the edge ring to the two or more RF power sources, the RF circuit configured to simultaneously tune at least one of an RF amplitude or an RF phase of individual signals of the two or more RF power sources.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure generally relate to apparatuses and methods for manipulating radio frequency power in a plasma process. BACKGROUND

[0002] An edge ring (e.g., a process kit) is a circular component that surrounds the perimeter of a substrate, such as a semiconductor substrate, during plasma processing in a process chamber. Due to the exposure of the edge ring to plasma within the process chamber, the edge ring can erode and need to be replaced or maintained over time. When the edge ring erodes significantly, the shape of the plasma sheath at the edge of the substrate distorts and changes the plasma processing characteristics at the edge of the substrate. The change in plasma processing characteristics results in undesirable processing effects at the edge of the substrate, thereby reducing the yield near the edge of the substrate. Furthermore, adjusting the sheath enables adjustment of the tilt of high aspect ratio features at the extreme edge of the substrate. There are other methods and apparatuses for controlling the plasma sheath, such as edge rings that are movable relative to the substrate. However, the inventors believe that such moving elements can unnecessarily cause an increase in particle formation in the process chamber. Alternatively, independent radio frequency (RF) generators with separate RF matching networks can directly drive the edge ring. However, such generators do not work well if multiple RF frequencies are used for substrate bias, and multiple generators with dual frequency matching networks can be very expensive.

[0003] Accordingly, the inventors provide improved apparatuses and methods for processing a substrate. SUMMARY

[0004] Disclosed herein are methods and apparatuses for manipulating dual radio frequency power in a plasma process. In some embodiments, a substrate support assembly includes an electrostatic chuck having one or more chucking electrodes embedded in the electrostatic chuck for chucking a substrate to a substrate support surface of the electrostatic chuck, an edge ring disposed on the electrostatic chuck and surrounding the substrate support surface, two or more radio frequency (RF) power sources coupled to the edge ring, and at least one of a base plate disposed below the electrostatic chuck or an electrode disposed in the electrostatic chuck, a matching network coupling the edge ring to the two or more RF power sources, and an RF circuit coupling the edge ring to the two or more RF power sources, the RF circuit configured to simultaneously tune at least one of an RF amplitude or an RF phase of individual signals of the two or more RF power sources.

[0005] According to at least some embodiments, a process chamber includes: a chamber body; a lid disposed on the chamber body; a plasma apparatus positioned above the lid; and a substrate support assembly positioned within the chamber body, the substrate support assembly including: an electrostatic chuck having one or more chucking electrodes embedded in the electrostatic chuck for chucking a substrate to a substrate support surface of the electrostatic chuck; an edge ring disposed on the electrostatic chuck and surrounding the substrate support surface; two or more radio frequency (RF) power sources coupled to the edge ring; a matching network coupling the edge ring to the two or more RF power sources; and an RF circuit coupling the edge ring to the two or more RF power sources, the RF circuit configured to simultaneously tune at least one of an RF amplitude or an RF phase of individual signals of the two or more RF power sources.

[0006] According to at least some embodiments, a method of processing a substrate positioned on a substrate support assembly includes: supplying radio frequency (RF) power from two or more RF power sources at two or more RF frequencies to each of electrodes disposed below the substrate and to an edge ring positioned adjacent to the electrodes via a matching network coupled between the two or more RF power sources and each of the electrodes and the edge ring; and tuning at least one of an RF amplitude or an RF phase of individual signals of the two or more RF power sources using an edge tuning circuit disposed between the two or more RF power sources and the edge ring to control a difference in a plasma sheath adjacent to the edge ring compared to a plasma sheath adjacent to the substrate.

[0007] Other and further embodiments of the present disclosure are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0008] Embodiments of the present disclosure, which have been briefly described above and discussed in greater detail below, can be understood by reference to the exemplary embodiments of the present disclosure illustrated in the appended drawings. However, the appended drawings illustrate only typical embodiments of the present disclosure and, therefore, should not be taken to be limiting within the scope thereof, since other equally effective embodiments can be resorted to as well.

[0009] Figure 1 is a schematic cross-sectional side view of a process chamber according to at least some embodiments of the present disclosure.

[0010] Figure 2A and Figure 2B illustrates a process chamber according to at least some embodiments of the present disclosure Figure 1enlarged schematic side view of portions of a substrate support assembly shown in FIG. 1.

[0011] Figures 3A to 3C is a schematic diagram of a plasma sheath relative to a substrate perimeter in accordance with at least some embodiments of the present disclosure.

[0012] Figure 4A and Figure 4B is a schematic circuit diagram showing RF circuitry in accordance with at least some embodiments of the present disclosure.

[0013] Figures 5A to 5B is a schematic diagram of RF circuitry in accordance with at least some embodiments of the present disclosure.

[0014] Figure 6 shows a method for processing a substrate positioned on a substrate support assembly in accordance with at least some embodiments of the present disclosure.

[0015] To facilitate an understanding of such embodiments, like reference characters are used throughout the disclosure to denote like elements. Figures are not drawn to scale and some elements can be simplified for the sake of clarity. Elements and features of one embodiment can be beneficially incorporated into other embodiments without further recitation. DETAILED DESCRIPTION

[0016] The present disclosure relates generally to apparatuses and methods of controlling radio frequency (RF) amplitudes of a substrate support assembly. In contrast to conventional methods and apparatuses that use a movable edge ring, and in contrast to moving the entire sheath up and down, the methods and apparatuses described herein reduce the problem of particles and provide independent control of each frequency (e.g., two or more frequencies) of multiple RF generators. Further, in contrast to conventional methods and apparatuses that use a separate RF generator for the edge ring at a single frequency, a tuning circuit that operates for two or more RF frequencies can save the cost of two or more separate RF generators and match the edge ring.

[0017] The present disclosure includes several tuning circuits that can be independently and simultaneously tuned at two or more RF frequencies. Because each RF frequency has a unique impact on several plasma parameters, such as ion energy distribution and ion angular distribution, having independent control of the RF frequencies provides more tuning capability for the substrate edge. For example, in at least some embodiments, an electrode can be positioned below a perimeter of a substrate and / or an edge ring positioned on a perimeter of a substrate support assembly.

[0018] During operation, the plasma sheath can drop to the edge ring proximity, for example, due to edge ring erosion, the capacitance of the variable capacitor can be adjusted to affect the RF amplitude near the substrate edge. Adjusting the RF amplitude via the electrode and variable capacitor results in adjustment of the plasma sheath near the substrate periphery. Sheath curvature at the substrate periphery can focus (e.g., increase etch rate) or de-focus (e.g., decrease etch rate) ions in a region about 0 to 5 mm - 10 mm from the wafer edge, which depends on process conditions.

[0019] Accordingly, benefits of the present disclosure include the ability to adjust the plasma sheath at the substrate edge instead of replacing chamber components, thereby improving device yield while reducing downtime, reducing particles, and reducing consumable waste. Additionally, the examples described herein allow for adjustment of the plasma sheath at the substrate edge without affecting plasma parameters at the substrate center, thereby providing a tuning knob for extreme edge process profiles and feature tilt correction.

[0020] Figure 1 is a schematic cross-sectional view of a process chamber 100 according to one example of the present disclosure. The process chamber 100 includes a chamber body 101 and a lid 102 disposed thereon, which together define an interior space. The chamber body 101 is typically coupled to an electrical ground 103. A substrate support assembly 104 is disposed within the interior space to support a substrate 105 thereon during processing (use). An edge ring 106 is positioned around a periphery of the substrate 105 on the substrate support assembly 104. The edge ring 106 is disposed on and around a substrate support surface of an electrostatic chuck.

[0021] The process chamber 100 can be one of an inductively coupled plasma (ICP) chamber and / or a capacitively coupled plasma (CCP) chamber. For example, in at least some embodiments, the process chamber 100 is a chamber that includes a CCP device 107 on the top. In at least some embodiments, the top of the process chamber 100 can be grounded.

[0022] The CCP device 107 generates a plasma of reactive species within the process chamber 100, and a system controller 108 is adapted to control the systems and subsystems of the process chamber 100 as described above.

[0023] The substrate support assembly 104 includes one or more electrodes, such as a first electrode 109 and a second electrode, such as a ring-shaped electrode 111 surrounding the first electrode 109. The first electrode 109 and the ring-shaped electrode 111 are each coupled to a plurality of RF power sources 110 providing different frequencies through a matching network 112 and a resonant edge tuning circuit 155 (e.g., hereinafter simply edge tuning circuit 155), which includes variable capacitors and inductors. The matching network 112 ensures that the output of the RF power sources 110 is efficiently coupled to the plasma to maximize the energy coupled to the plasma. The matching network 112 generally matches the complex impedance of the plasma to 50 ohms. To facilitate dynamic matching as the plasma characteristics change during processing, the matching network 112 can be continuously adjusted to ensure that the match is maintained throughout the process.

[0024] The edge tuning circuit 155 is an RF circuit operating near resonance that enables the voltage to be adjusted above and / or below the power source voltage, as described in more detail below. The RF power sources 110 are used to bias a substrate 105 disposed on an upper surface 160 of the substrate support assembly 104. The RF power sources 110 can exemplarily be sources of RF energy up to about 10,000 W (but not limited to about 10,000 W), which can be provided at one or more frequencies, such as 400 kHz, 2 MHz, 13.56 MHz, 27 MHz, 40 MHz, or 60 MHz. The RF power sources 110 can include two or more independent RF power sources configured to provide RF energy at two or more respective frequencies. For example, in at least some embodiments, the RF power sources 110 can include an RF power source 110a and an RF power source 110b each configured to provide RF energy at a corresponding frequency (e.g., 400 kHz and 2 MHz), and an optional RF power source 110c can be provided and can be configured to provide RF energy at frequencies of 400 kHz, 2 MHz, and / or 40 MHz. The RF power sources 110 can be capable of generating one or both of continuous power or pulsed power. The first electrode 109 is coupled to a chuck power source 114 to facilitate chucking of the substrate 105 to the upper surface 160 during processing.

[0025] The CCP device 107 is disposed above the lid 102 and is configured to capacitively couple RF power into the process chamber 100 to generate a plasma 116 within the process chamber 100. The CCP device 107 can be adjusted as needed to control the profile or density of the plasma 116 formed. The CCP device 107 is coupled to an RF power supply 121 via an RF feed structure 124 through a matching network 122 (similar to the matching network 112). The RF power supply 121 can illustratively be capable of generating up to about 60,000 W (but is not limited to about 60,000 W) at a tunable frequency in the range from 50 kHz to 150 MHz, although other frequencies and powers can be used as needed for a particular application.

[0026] In some examples, a power divider (not shown), such as a dividing capacitor, can be provided between the RF feed structure 124 and the RF power supply 121 to control the relative amounts of RF power provided. For example, a power divider can be used in embodiments in which the process chamber 100 includes an ICP device. In such embodiments, the power divider can be incorporated into the matching network 122.

[0027] A heater element 128 can be disposed on the lid 102 to facilitate heating the interior of the process chamber 100. The heating element 128 can be disposed between the lid 102 and a plasma device, such as the CCP device 107. In some examples, the heater element 128 can comprise a resistive heating element and can be coupled to a power supply 130, such as an AC power supply, configured to provide sufficient energy to control the temperature of the heater element 128 within a desired range.

[0028] During operation, a substrate 105, such as a semiconductor wafer or other substrate suitable for plasma processing, is placed on the substrate support assembly 104. A substrate lift pin 146 is movably disposed in the substrate support assembly 104 to assist in transferring the substrate 105 onto the substrate support assembly 104. After the substrate 105 is positioned, a process gas is supplied from a gas panel 132 through an inlet port 134 into an interior volume of the chamber body 101. The process gas is ignited into a plasma 116 in the process chamber 100 by applying power from the RF power supply 121 to the CCP device 107. In some examples, power from the RF power source 110 can also be provided through the matching network 112 to the first electrode 109 and / or the edge ring 106 within the substrate support assembly 104. Alternatively or in addition, power from the RF power source 110 (e.g., two or more of the RF power sources 110a-110c) can also be provided through the matching network 112 to the substrate support and / or other electrodes within the substrate support assembly 104. In at least some embodiments, a DC power source 131 can be connected to the substrate support assembly 104 (e.g., to the ring electrode 111), and the DC power source 131 can be configured to provide a clamping force to clamp the edge ring 106 to the substrate support (e.g., to a ceramic ring 250 disposed on the substrate support as described below) to, for example, improve thermal control of the edge ring 106 during operation.

[0029] The pressure inside the process chamber 100 can be controlled using the valve 136 and the vacuum pump 138. The temperature of the chamber body 101 can be controlled using fluid-containing conduits (not shown) that pass through the chamber body 101.

[0030] The process chamber 100 includes a system controller 108 to control the operation of the process chamber 100 during processing. The system controller 108 includes a central processing unit (CPU) 140, memory 142 (e.g., non-transitory computer-readable medium), and support circuits 144 for the CPU 140, and advantageously controls the components of the process chamber 100. The system controller 108 can be one of any form of general-purpose computer processor that can be used in an industrial setting for controlling various chambers and sub-processors. The memory 142 stores software that can be executed to implement the functions as described herein for controlling the operation of the process chamber 100.

[0031] During processing, the upper surface 150 of the edge ring 106 may be etched. Etching alters plasma characteristics, which may change the plasma 116 at or near the edge of the substrate 105. In one embodiment, the software of the memory 142 includes instructions for manipulating various RF circuits provided herein to obtain a target amplitude of the voltage at the edge ring 106 to tune the process profile and / or feature tilt on the edge of the substrate 105.

[0032] Figure 2A and Figure 2B At least some embodiments according to this disclosure are shown. Figure 1 The diagram shows an enlarged schematic side view of a portion of the substrate support assembly 104. The substrate support assembly 104 includes a ground plane 200 (surrounding an insulating layer 205), a facilities plate 210, and an electrostatic chuck 215, which are arranged in a vertically stacked configuration. A quartz ring 220 circumscribes the facilities plate 210 and the electrostatic chuck 215 to insulate the electrostatic chuck 215 from the ground plane 200. The electrostatic chuck 215 includes one or more adsorption electrodes (e.g., a first electrode 109) embedded therein for adsorbing the substrate 105 onto the support surface of the electrostatic chuck 215. A plasma shield 225 is disposed on the upper surface of the quartz ring 220 to facilitate plasma containment within the process chamber 100. Figure 1 As shown in the figure, the quartz ring 230 is positioned on the upper surface of the plasma shield 225.

[0033] Device plate 210 may be made of a conductive material (such as aluminum) or other suitable conductive material, and device plate 210 is positioned between the lower portion of ground plane 200 and electrostatic chuck 215. Device plate 210 is configured to route fluid and / or gas from an input position (e.g., at its bottom, not shown) to an output position (e.g., at its top, not shown). Electrostatic chuck 215 includes one or more channels 235 formed in a first material 236, through which fluid is supplied to facilitate temperature control of substrate support assembly 104. First material 236 is a metallic material, such as aluminum. Electrostatic chuck 215 includes a first electrode 109 embedded in a second material 240. Second material 240 is a dielectric material, such as a ceramic material, such as alumina or aluminum nitride. Heater 245 is disposed adjacent to or within electrostatic chuck 215 to facilitate temperature control of substrate 105. Heater 245 may be, for example, a resistance heater having multiple resistance heating elements embedded therein.

[0034] A ceramic ring 250 is disposed on the electrostatic chuck 215 (e.g., on the first material 236 or the heater 245) and surrounds a radially outward edge of the second material 240. The ceramic ring 250 can be made of, for example, aluminum oxide or aluminum nitride, and can have a thickness in a range from about 1 millimeter to about 20 millimeters. One or more O-rings can be provided between the ceramic ring 250 and the second material 240 to protect any bonding material that would otherwise be exposed therebetween.

[0035] The annular electrode 111 can be a component of the ceramic ring 250 or a separate component. For example, in the illustrated embodiment, the annular electrode 111 is embedded in the ceramic ring 250. The annular electrode 111 can be positioned about 0.3 millimeters to about 1 millimeter from an upper surface of the ceramic ring 250, such as about 0.75 millimeters. The annular electrode 111 can have a width of about 3 millimeters to about 20 millimeters, such as about 15 millimeters.

[0036] The annular electrode 111 is positioned radially outward of the perimeter of the substrate 105 and below the edge ring 106. In one example, the annular electrode 111 can have an inner diameter that is greater than 200 millimeters, or greater than 300 millimeters, or greater than 450 millimeters. The annular electrode 111 is electrically coupled to ground and / or the matching network 112 through an edge tuning circuit 155, which can include one or more capacitors and / or inductors. The annular electrode 111 can be coupled to the edge tuning circuit 155 through a plurality of transmission lines 265 (two are shown). For example, the annular electrode 111 can be coupled to the edge tuning circuit 155 through three transmission lines 265 that are spaced apart at uniform intervals (e.g., 120 degrees) around the substrate support assembly 104.

[0037] The edge ring 106 is positioned on (over) the ceramic ring 250 and in contact with the ceramic ring 250 and the second material 240. In one example, the edge ring 106 can be formed of silicon carbide, graphite coated with silicon carbide, or low resistivity doped silicon. The edge ring 106 encircles the substrate 105 and reduces undesirable material etching or deposition at the radially outward edge of the substrate 105.

[0038] Referring to Figure 2B During processing, a plasma sheath 260 can be formed over the surface of the substrate 105 (e.g., as in the gap between the edge ring 106 and the substrate 105). The plasma sheath 260 can be formed by a plasma generated by the plasma source 120. The plasma sheath 260 can have a thickness of about 1 millimeter to about 20 millimeters, such as about 10 millimeters. Figure 2BAs described above, the processing conditions can etch the upper portion of the edge ring 106, resulting in undesirable processing of the edge of the substrate 105, such as rounding, sometimes referred to as a "rollover effect." The undesirable processing reduces component yield and affects center-to-edge uniformity. To reduce these undesirable effects, a conventional approach is to frequently replace the edge ring 106. However, frequent replacement of the edge ring 106 is costly in terms of the cost of new edge rings and in terms of the significant downtime required to replace the edge ring.

[0039] In contrast to conventional approaches, in the examples described herein, the annular electrode 111 is coupled to the matching network 112 through the edge tuning circuit 155 to the ground and / or RF power source (e.g., two or more of the RF power sources 110a-110c) to adjust the RF amplitude (and / or phase) near the edge ring 106 and thereby adjust the plasma sheath 260 near the edge ring 106. Further, the two or more of the RF power sources 110a-110c and the matching network 112 are configured to be shared by the substrate 105 and the annular electrode 111 disposed below the edge ring 106 during use.

[0040] In some embodiments, it is desirable to have the plasma sheath 260 above the edge ring 106 thicker or thinner than the plasma sheath 260 above the substrate 105 to adjust one or a combination of film etch, deposition profile, or feature tilt angle near the edge of the substrate. Controlling the RF amplitude and / or RF phase at the edge ring 106 relative to the RF amplitude and / or RF phase at the substrate 105 allows such process edge profile tuning.

[0041] Because of the relatively reduced thickness of the ceramic ring 250 compared to conventional approaches, the RF power initially delivered to the electrostatic chuck 215 has a high RF coupling to the edge ring 106. In other words, the RF amplitude on the edge ring 106 can be higher than the RF amplitude on the substrate 105.

[0042] A gap 255 can be provided between the upper surface of the ceramic ring 250 and the lower surface of the edge ring 106. The gap 255 can be used to reduce the coupling between the annular electrode 111 and the plasma sheath 260 to reduce the RF current flowing to the edge tuning circuit 155. The thickness of the gap 255 can be selected to provide a desired amount of decoupling.

[0043] Other examples of the present disclosure can be contemplated in addition to the examples described above. In one example, the length of transmission line 265 can have a length of lambda (wavelength) divided by 2 (e.g., lambda / 2) to facilitate a matched impedance in at least one frequency. In another example, the width of ring electrode 111 can be selected as desired to increase or decrease the electrical coupling with edge ring 106. In another example, gap 255 can be omitted. In another example, a conductive thermal gasket (e.g., a silicone-based thermal gasket can occupy gap 255.

[0044] In another example, edge tuning circuit 155 can be coupled to matching network 112 and then to RF power sources 110a-110c instead of (or in addition to) ground. In such an example, edge tuning circuit 155 would facilitate adjustment of capacitive coupling instead of parasitic effects as described above.

[0045] Edge tuning circuit 155 can include one or more variable capacitors and one or more inductors coupled to ring electrode 111, as described in more detail below with respect to Figure 4A and Figure 4B The resonant frequency of the tuning circuit can be substantially close to the operating frequency, which makes large variations in RF amplitude much greater than and much less than the RF amplitude of the substrate.

[0046] Figures 3A to 3C is a schematic illustration of plasma sheath 260 relative to the perimeter of substrate 105 in accordance with at least some embodiments of the present disclosure. Figure 3A is shown prior to etching edge ring 106 relative to edge ring 106 and substrate 105. As Figure 3A shown, prior to etching edge ring 106, the upper surface of edge ring 106 and substrate 105 are substantially coplanar. Prior to etching edge ring 106, plasma sheath 260 is substantially parallel and equidistant from the upper surface of edge ring 106 and substrate 105. Figure 3A The profile of plasma sheath 260 shown in

[0047] After processing a predetermined number of substrates, conditions in the process chamber cause the edge ring 106 to be undesirably eroded. In one example, the upper surface of the edge ring 106 can be eroded, thereby reducing the thickness of the edge ring 106. The eroded edge ring 106 no longer shares a coplanar upper surface with the substrate 105. Due to the interaction between the edge ring 106 and the charged particles in the plasma, the profile of the plasma sheath 260 changes in the presence of edge ring 106 erosion and is unable to maintain the equidistant spacing between the surface of the edge ring 106 and the substrate 105. The profile of the plasma sheath 260 can cause "rounding" or other undesirable processing of the radially outward edge of the substrate 105. The rounding at the edge of the substrate reduces the usable surface of the substrate 105, thus reducing the device yield per substrate. The undesirable rounding can be generally referred to as a "roll-off effect." In conventional systems, to correct for the rounding, the eroded edge ring 106 is replaced, thereby increasing the direct cost and the cost of production loss due to process downtime. Conversely, examples of the present disclosure utilize the ring electrode 111 to adjust the RF amplitude, and thus the position of the plasma sheath 260 over the eroded edge ring 106. For example, Figure 3B and Figure 3C show low and high edge ring 106 voltages, respectively, such that after compensation for the eroded edge ring 106 by means of the various RF circuitry provided in the present disclosure, the plasma sheath 260 can be adjusted to reestablish the original (e.g., planar) profile of the plasma sheath 260.

[0048] The reestablished plasma sheath 260 does not cause a "roll-off effect" on the substrate 105, thereby preventing damage to the substrate 105 and maximizing the usable surface of the substrate 105. Furthermore, because the eroded edge ring 106 can continue to be used in an eroded state, the time between preventative maintenance is extended, thereby reducing process downtime. Additionally, the eroded edge ring requires less frequent replacement, thereby reducing the expense of consumable parts.

[0049] Figure 4A and Figure 4B are schematic circuit diagrams showing RF circuitry in accordance with at least some embodiments of the present disclosure. For ease of illustration, Figure 4A shows the RF circuitry 400A overlaid on a partial view of the substrate support assembly 104. The RF circuitry 400A describes the functional relationship between the components of the system.

[0050] In the RF circuit 400A, there is a capacitive element CI between the base plate 405 and the edge ring 106. Two or more RF power sources 110 can be coupled to the edge ring 106 and at least one of the base plate 405, which can be disposed below the electrostatic chuck 215, or an electrode (e.g., the first electrode 109), which is disposed in the electrostatic chuck 215. There is a capacitive element C2 between the edge ring 106 and the plasma 116 in the plasma sheath 260. The capacitive element C3 is the capacitance between the edge ring 106 and the ring electrode 111. There is a capacitive element C4 between the ring electrode 111 and the base plate 405. There is a capacitive element C7 between the substrate 105 and the plasma 116 in the plasma sheath 260. The capacitive element C8 is the capacitance between the substrate 105 and the base plate 405 when RF power is launched through (to) the base plate 405. In at least some embodiments, the capacitive element C8 can be the capacitive element between the first electrode 109 and the substrate 105 when RF power is launched through the first electrode 109 (see, e.g., the RF circuit 400B of Figure 4B The capacitive elements C2, C3, C4, and C9 correspond to the edge capacitance circuit 408A. The capacitive elements C7 and C8 correspond to the center capacitance circuit 408B.

[0051] In some embodiments, the base plate 405 corresponds to the device plate 210 (shown in Figure 2A and Figure 2B In some embodiments, the heater 245 can be omitted, and a bonding layer 410 can be disposed between the base plate 405 (or the device plate 210) and the second material 240.

[0052] Figures 5A to 5B is a schematic diagram of the edge tuning circuit 155, and Figure 6 shows a method for processing a substrate 105 positioned on a substrate support assembly 104 according to at least some embodiments of the present disclosure. When the substrate 105 is side- shared with RF power sources 110a, 110b, 110c, etc., the edge tuning circuit 155 topology of Figure 5A may be configured to adjust the edge ring 106 RF amplitude and phase at multiple RF frequencies (e.g., frequencies provided by two or more RF power sources 110a, 110b, 110c, etc.) simultaneously. Moreover, the RF voltage at the center of the substrate 105 can be maintained at a constant value when adjusting the RF amplitude and phase at the edge ring 106.

[0053] Referring to Figure 5AIn at least some embodiments, the edge tuning circuit 155 can include a plurality of circuit blocks numbered 0, 1, 2,... and connected in parallel between the ground and the matching network 112. For illustrative purposes, the edge tuning circuit 155 is shown to include three circuit blocks 5000, 5001, and 5002 (hereinafter referred to as circuit blocks 500 n ). The middle legs of the circuit blocks 500 n are connected by inductors 501 therebetween, which are connected to the output (e.g., the looped antenna 111) of the edge tuning circuit 155.

[0054] The circuit blocks 500 n include two or more electrical components, e.g., the circuit block 5000 includes electrical components X1-X3 and an additional inductor (e.g., the inductor 501) in the middle leg to supplement the inductor present in X1. Each of the inductors 501 in the circuit blocks 500 n may have the same inductance or different inductances depending on the inductance of the inductors in the individual electrical components of the circuit blocks 500 n . Similarly, the circuit blocks 5001 and 5002 include electrical components X4-X6 and X7-X9, respectively. Each of the electrical components X1-X9 can have four possible configurations as shown in Figure 5B . For example, each of the electrical components X1-X9 can include one or more variable capacitors 502 (see (a) of Figure 5B ), inductors 504 (see (b) of Figure 5B ), variable capacitors 502 and inductors 504 in series (see (c) of Figure 5B ), and / or variable capacitors 502 and inductors 504 in parallel (see (d) of Figure 5B ). In at least some embodiments, the inductors 504 can be variable inductors. In at least some embodiments, the electrical components X1-X3 of the circuit block 5000 of the edge tuning circuit 155 can include one or more inductors 504 and one or more variable capacitors 502 (and / or one or more LC series and / or LC parallel circuits) in one or more pairs. In at least some embodiments, Figure 5B the variable capacitors 502 of (a) can be the same or different from the variable capacitors 502 of (c) and (d). Similarly, Figure 5B the inductors 504 of (b) can be the same or different from the inductors 504 of (c) and (d).

[0055] The circuit blocks 500 nThe electrical components X1, X2, X3, etc. within a circuit block 500n can be designated by the general notation X i+3n where n = 0, 1, 2,... and denotes the circuit block number, and i = 1, 2, 3 and denotes the relative position of the component within the circuit block, and 3 denotes the number of electrical components in the circuit block. The components X 1+3n 1+3n are connected between ground and the intermediate branch, the components X 2+3n 2+3n are connected between the input line of the tuning circuit (e.g., the output of the matching network 112) and the intermediate branch, and the components X 3+3n 3+3n are connected in the intermediate branch. For example, within the circuit block 5001, n = 1, three X components are numbered with 4 (= 1 + 3*1), 5 (= 2 + 3*1), and 6 (= 3 + 3*1), e.g., X4, X5, and X6.

[0056] Each circuit block 500n has two pairs of (X 1+3n ,X 2+3n ) and (X 1+3n ,X 3+3n ). For example, the circuit block 5000 includes the pairs (X1, X2) and (X1, X3), as shown in Figure 5A Each pair of components (X 1+3n ,X 2+3n ) or (X 1+3n , X 3+3n ) includes at least one variable capacitor 502 (e.g., as shown in (a), (c), and / or (d) of Figure 5B ) and at least one inductor 504 (e.g., as shown in (b), (c), and / or (d) of Figure 5B ). For example, within the circuit block 5000, n = 0, the two pairs (X1, X2) and (X1, X3) each include a variable capacitor 502 (e.g., as shown in (a), (c), and / or (d) of Figure 5B ) and an inductor 504 (e.g., as shown in (b), (c), and / or (d) of Figure 5B ). Similarly, within the circuit block 5001, n = 1, the two pairs (X4, X5) and (X4, X6) each include a variable capacitor 502 (e.g., as shown in (a), (c), and / or (d) of Figure 5B ) and an inductor 504 (e.g., as shown in (b), (c), and / or (d) of Figure 5B ). Likewise, within the circuit block 5002, n = 2, the two pairs (X7, X8) and (X7, X9) each include a variable capacitor 502 (e.g., as shown in (a), (c), and / or (d) of Figure 5Binductor 504 (e.g., as shown in Figure 5B (b), (c), and / or (d). In at least some embodiments, if the circuit block 500 n X 1+3n does not include a series inductor (e.g., as shown in Figure 5B (a) and / or (d), a separate inductor can be placed in the middle branch of the circuit block closer to the output. For example, in Figure 5A (a), each circuit block 500 n includes an inductor 501 in the middle branch. In at least some embodiments, the fourth inductor in the middle branch is not included in the circuit block closest to the output of the edge tuning circuit 155.

[0057] As described above, the edge tuning circuit 155 operates near resonance, which enables the edge tuning circuit 155 to adjust the voltage to be higher or lower than the RF power source 110. Thus, each of the circuit blocks 500 n can be tuned for two RF frequencies independently and simultaneously with at least two variable capacitors 502 within the circuit block (e.g., circuit block 5000). When more than two RF frequencies need to be tuned simultaneously, more than one of the circuit blocks 500 n can be connected in parallel, as described above and shown in Figure 5A When an odd number of RF frequencies need to be tuned simultaneously, one of the variable capacitors in one of the electrical elements X i+3n may be replaced with a fixed capacitor (not shown), or one of the electrical elements X i+3n may not be used, e.g., X5 or X8.

[0058] In at least some embodiments, such as when a non-zero DC voltage is needed at the output, a blocking capacitor 506 (e.g., having a relatively large capacitance compared to the variable capacitors 502) can be placed in the middle branch of the circuit block, and a DC power supply 508 can be placed between the blocking capacitor 506 and the output (e.g., the loop electrode 111). If at least one capacitor (e.g., a variable capacitor or a fixed capacitor) is already provided in the middle branch, the DC power supply 508 can be placed between the output (e.g., the loop electrode 111) and the capacitor closest to the output. For example, in the circuit block 5002 of Figure 5A , the blocking capacitor 506 can be placed between the electrical element X7 and the inductor 501 closest to the output, and the DC power supply 508 can be connected on the output side of the blocking capacitor 506.

[0059] Figure 6The following are at least some embodiments of the present disclosure for (e.g., using circuit block 500 including FIG5) n The edge tuning circuit 155) processes a substrate positioned on a substrate support assembly in a method 600. When power is applied to the ring electrode 111 (e.g., RF power is supplied from two or more RF power sources 110 at different RF frequencies), an RF voltage and current are generated at the edge ring 106 due to the coupling described above. The RF voltage and phase at the edge ring 106 are relative to the edge tuning circuit 155 (e.g., comprising one or more circuit blocks 500). n The relationship between the voltage and phase at the output of the edge ring 106 follows the physical rules of transmission line theory and circuit theory. The relationship between the RF voltage and phase at the edge ring 106 and the voltage and phase at the output of the edge tuning circuit 155 can be calibrated and determined for a specific hardware configuration for each RF frequency of the RF power source 110. Similarly, the relationship between the RF voltage and phase at the substrate 105 and the voltage and phase at the output of the matching network 112 can also be calibrated and determined for a specific hardware configuration for each RF frequency of the RF power source 110. Therefore, in at least some embodiments, the edge tuning circuit 155 can be calibrated to find the relationship between the RF amplitude and phase between the substrate 105 and the output of the edge tuning circuit 155 at each RF frequency of the RF power sources 110a, 110b, 110c, etc. Similarly, the relationship between the RF amplitude and RF phase between the output of the edge ring 106 and the matching network 112 can also be calibrated.

[0060] At 602, RF power is supplied at two or more RF frequencies from two or more RF power sources (e.g., RF power sources 110a, 110b, 110c) to each of the electrodes disposed beneath the substrate and to an edge ring (e.g., edge ring 106) located adjacent to these electrodes via a matching network (e.g., matching network 112), the matching network being coupled between the two or more RF power sources and each of the electrodes and the edge ring. More specifically, during plasma processing of the substrate 105, RF power from two or more of the RF power sources 110a, 110b, 110c, etc., is supplied / feeded to the substrate 105 via coupling through the matching network 112 and the substrate 405 or the first electrode 109 (e.g., adsorption electrode). Simultaneously, RF power from the RF power sources 110a, 110b, 110c, etc., is also supplied / feeded to the edge ring 106 via coupling through the matching network 112, the edge tuning circuit 155, and the ring electrode 111.

[0061] At 604, at least one of the RF amplitudes or RF phases of the individual signals of the two or more RF power sources can be tuned using the edge tuning circuit disposed between the two or more RF power sources and the edge ring, e.g., to control the difference in the plasma sheath adjacent the edge ring as compared to the plasma sheath adjacent the substrate.

[0062] More specifically, the RF voltage, RF current, and / or RF phase at the output of the edge tuning circuit 155 and the matching network 112 can be measured at each RF frequency of the two or more RF power sources 110. Thereafter, the RF amplitudes and / or RF phases of the individual signals of the two or more RF power sources 110a, 110b, 110c, etc. can be tuned simultaneously.

[0063] For example, based on the measured RF voltage, RF current, and / or RF phase at the output of the edge tuning circuit 155 and the matching network 112, the RF amplitudes and RF phases at the substrate 105 and the edge ring 106 can be calculated. For example, using the calibration model described above, the RF voltage, RF current, and / or RF phase at the substrate 105 and the edge ring 106 can be measured / calculated at each RF frequency of the RF power sources using, e.g., the system controller 108.

[0064] To compensate for erosion of the edge ring 106 or non-uniformity of the plasma sheath or feature tilt near the edge of the substrate 105, various RF voltage ratios between the substrate 105 and the edge ring 106 at different RF frequencies can be calculated (determined) at various plasma processing conditions. Similarly, various phase differences between the substrate 105 and the edge ring 106 can also be calculated (determined). To achieve the targeted voltage ratios and phase differences at each RF frequency simultaneously, the desired variable capacitor(s) 502 value(s) within the circuit block 500 of the edge tuning circuit 155 can be calculated based on the circuit model of the edge tuning circuit 155 and the pre-calibration results described above. Figure 4A and Figure 4B The desired variable capacitor(s) 502 value(s) within the circuit block 500 of the edge tuning circuit 155 can be calculated using the circuit model of the edge tuning circuit 155 and the pre-calibration results described above. This calculation can be performed using the system controller 108. n

[0065] Using the calculated capacitor values, the variable capacitors 502 can be adjusted. While the variable capacitors 502 are being adjusted, the system controller 108 monitors the RF voltage, RF current, and / or RF phase at the output of the edge tuning circuit 155 and the matching network 112 to re-adjust the model predicted capacitor values for achieving the targeted voltage ratios and phase differences at the multiple RF frequencies.

[0066] The output power of the two or more RF power sources 110 can be adjusted while the circuit block 500 of the edge tuning circuit 155 is being adjusted to achieve the targeted voltage ratios and phase differences at the multiple RF frequencies. n ​One or more of the variable capacitors 502 in the RF circuit 400A and the RF circuit 400B can be tuned to maintain a constant RF voltage at the substrate 105 at each applied RF frequency. When this is done, for example, when tuning process performance at the substrate edge by tuning the edge tuning circuit 155, process performance at the center of the substrate 105 is not affected, thereby advantageously providing a tuning knob for extreme edge process profile control and feature tilt correction with minimal or no impact on plasma parameters at the center of the substrate. Furthermore, the examples described herein allow for adjustment of the plasma sheath near the substrate edge without affecting plasma parameters at the center of the substrate, thereby providing a tuning knob for extreme edge process profile control and feature tilt correction, and improving device yield while reducing downtime, particle generation, and reducing the cost of consumables.

[0067] To achieve and maintain the target voltage ratio and phase difference between the substrate 105 and the edge ring 106 while maintaining a constant RF voltage at the substrate 105, the system controller 108 performs a closed control feedback loop 606 from 602 to 604 throughout the plasma processing time.

[0068] Testing of the substrate support assembly 104 with the RF circuit 400A and the RF circuit 400B indicates enhanced plasma control at the substrate edge. Furthermore, feature tilt control is enhanced. For example, testing with a 300 mm substrate indicates that low and high voltages applied to the annular electrode 111 under the edge ring 106 have shown to produce a range of greater than about 7 degrees at a radius of 146 mm or greater. Furthermore, testing of the substrate support assembly 104 with a quartz cover ring (not shown) produced results similar to the testing of the substrate support assembly 104 without the quartz cover ring. Thus, the use of the quartz cover ring provides control of the plasma sheath as well as reduction of particle generation.

[0069] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure can be devised without departing from the basic scope thereof.

Claims

1. A substrate support assembly, comprising: an electrostatic chuck having one or more chucking electrodes embedded in the electrostatic chuck for chucking a substrate to a substrate support surface of the electrostatic chuck; an edge ring disposed on the electrostatic chuck and surrounding the substrate support surface; two or more radio frequency (RF) power sources coupled to the edge ring and at least one of a base plate disposed below the electrostatic chuck or an electrode disposed in the electrostatic chuck; a matching network coupling the edge ring to the two or more RF power sources; and an RF circuit coupling the edge ring to the two or more RF power sources, the RF circuit configured to simultaneously tune at least one of an RF amplitude or an RF phase of individual signals of the two or more RF power sources using two or more circuit blocks connected in parallel to each other and disposed between the two or more RF power sources and the edge ring.

2. The substrate support assembly of claim 1, further comprising: a controller configured to adjust two or more variable capacitors to control at least one of an RF voltage, an RF current, or an RF phase at the edge ring via a ring electrode coupled to the RF circuit and disposed below the edge ring.

3. The substrate support assembly of claim 1, wherein the RF circuit operates near resonance, and wherein each of the two or more circuit blocks includes an electrical element connected between a ground and an intermediate leg of the circuit block, an electrical element connected between an input line of the matching network and the intermediate leg of the circuit block, and an electrical element connected in the intermediate leg of the circuit block.

4. The substrate support assembly of any of claims 1 to 3, wherein the electrical elements include variable capacitors and at least one of inductors, variable capacitors in series with inductors, or variable capacitors in parallel with inductors.

5. The substrate support assembly of any of claims 1 to 3, wherein an output of one of the two or more circuit blocks includes a blocking capacitor and a DC power supply disposed between the blocking capacitor and the output of one of the two or more circuit blocks.

6. The substrate support assembly of claim 1, wherein the two or more RF power sources are coupled to the electrode disposed in the electrostatic chuck.

7. The substrate support assembly of claim 1, wherein the two or more RF power sources are coupled to the base plate.

8. The substrate support assembly of claim 1, further comprising a DC power source coupled to a ring electrode disposed below the edge ring and configured to provide a clamping force on the edge ring during operation. ​ 9. The substrate support assembly of any of claims 1-3 or 6-8, wherein the two or more RF power sources and the matching network are configured to be shared during use by the substrate and an annular electrode disposed beneath the edge ring.

10. A process chamber, comprising: a chamber body; a lid disposed on the chamber body; a plasma device positioned above the lid; and a substrate support assembly positioned within the chamber body, the substrate support assembly comprising: an electrostatic chuck having one or more chucking electrodes embedded in the electrostatic chuck for chucking a substrate to a substrate support surface of the electrostatic chuck; an edge ring disposed on the electrostatic chuck and surrounding the substrate support surface; two or more radio frequency (RF) power sources coupled to the edge ring and at least one of a base plate disposed beneath the electrostatic chuck or an electrode disposed in the electrostatic chuck; a matching network coupling the edge ring to the two or more RF power sources; and an RF circuit coupling the edge ring to the two or more RF power sources, the RF circuit configured to simultaneously tune at least one of an RF amplitude or an RF phase of individual signals of the two or more RF power sources using two or more circuit blocks connected in parallel to each other and disposed between the two or more RF power sources and the edge ring.

11. The process chamber of claim 10, further comprising: a controller configured to adjust two or more variable capacitors to control at least one of an RF voltage, an RF current, or an RF phase at the edge ring via an annular electrode coupled to the RF circuit and disposed beneath the edge ring.

12. The process chamber of claim 10, wherein the RF circuit operates near resonance, and wherein each of the two or more circuit blocks includes an electrical element connected between ground and an intermediate leg of the circuit block, an electrical element connected between an input line of the matching network and the intermediate leg of the circuit block, and an electrical element connected in the intermediate leg of the circuit block.

13. The process chamber of any of claims 10-12, wherein the electrical elements include variable capacitors and at least one of inductors, variable capacitors in series with inductors, or variable capacitors in parallel with inductors.

14. The process chamber of any of claims 10-12, wherein an output of one of the two or more circuit blocks includes a blocking capacitor and a DC power supply disposed between the blocking capacitor and the output of the one of the two or more circuit blocks.

15. A method of processing a substrate positioned on a substrate support assembly, comprising: ​ RF power at two or more RF frequencies is supplied from two or more RF power sources to each of electrodes disposed below the substrate and to an edge ring positioned adjacent to the electrodes by matching networks coupled between the two or more RF power sources and each of the electrodes and the edge ring; and at least one of RF amplitude or RF phase of individual signals of the two or more RF power sources is tuned using an edge tuning circuit disposed between the two or more RF power sources and the edge ring to control a difference of a plasma sheath adjacent to the edge ring compared to a plasma sheath adjacent to the substrate, the edge tuning circuit including two or more circuit blocks connected in parallel to each other and disposed between the two or more RF power sources and the edge ring.

16. The method of claim 15, further comprising: measuring at least one of RF voltage, RF current, or RF phase at outputs of the edge tuning circuit and the matching networks at the two or more RF frequencies of the two or more RF power sources; and calculating RF amplitude and RF phase at the substrate and the edge ring based on the at least one of RF voltage, RF current, or RF phase measured at outputs of the edge tuning circuit and the matching networks; and wherein tuning at least one of the RF amplitude or the RF phase of individual signals of the two or more RF power sources using the edge tuning circuit is based on the calculated RF amplitude and RF phase at the substrate and the edge ring.

17. The method of claim 15, wherein tuning at least one of the RF amplitude or the RF phase of individual signals of the two or more RF power sources further comprises: adjusting two or more variable capacitors in the edge tuning circuit to a capacitance value based on the calculated RF amplitude and RF phase to control at least one of RF voltage, RF current, or RF phase at the edge ring to a predetermined value relative to the substrate; and adjusting output power of the two or more RF power sources to maintain the substrate at a constant RF voltage at each of the two or more RF frequencies when adjusting the two or more variable capacitors in the edge tuning circuit.

18. The method of any of claims 15 to 17, wherein adjusting the two or more variable capacitors in the edge tuning circuit to the capacitance values comprises: increasing at least one of RF voltage, RF current, or RF phase at the edge ring such that the plasma sheath adjacent to the substrate is increased.

19. The method of any one of claims 15 to 17, further comprising: using a closed control feedback loop throughout a plasma processing time.

20. The method of any of claims 15 to 17, further comprising: measuring at least one of RF voltage, RF current, or RF phase at outputs of the edge tuning circuit and the matching networks at the two or more RF frequencies of the two or more RF power sources; computing RF amplitudes and RF phases at the substrate and the edge ring based on at least one of the RF voltages, the RF currents, or the RF phases measured at outputs of the edge tuning circuit and the matching network; adjusting two or more variable capacitors in the edge tuning circuit to capacitance values to control at least one of the RF voltages, the RF currents, or the RF phases at the edge ring to predetermined values relative to the substrate based on the computed RF amplitudes and RF phases; and adjusting output powers of the two or more RF power sources to maintain the substrate at constant RF voltages at each of the two or more RF frequencies while adjusting the two or more variable capacitors in the edge tuning circuit. ​

Images