Edge Uniformity Tunability on Bipolar Electrostatic Chucks

Abstract

Embodiments of the present technology may include an electrostatic chuck. The chuck may include a top surface that defines a recessed portion of the chuck. The recessed portion of the chuck may be configured to support a substrate. The chuck may further include a first electrode and a second electrode. The first electrode and the second electrode may be disposed within the chuck. The first electrode and the second electrode may be substantially coplanar. Additionally, the chuck may include a third electrode. The third electrode may be disposed within the chuck. Furthermore, the third electrode may have an annular shape. The third electrode may be separate from the first electrode and the second electrode. Additionally, the third electrode may be substantially parallel to the first electrode and the second electrode. Systems and methods including the electrostatic chuck are also described.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of priority of U.S. Patent Application No. 16 / 690,562, filed on November 21, 2019, the content of which is incorporated herein by reference in its entirety for all purposes. Technical field

[0003] The present technology relates to semiconductor substrate systems and methods. More specifically, the present technology relates to methods and systems having an electrostatic chuck with multiple electrodes. Background art

[0004] In the fabrication of integrated circuits and other electronic devices, plasma processing is commonly used to deposit or etch various material layers. For example, plasma - enhanced chemical vapor deposition (PECVD) processing is a chemical process in which electromagnetic energy is applied to at least one precursor gas or precursor vapor to convert the precursor into a reactive plasma. The plasma can be generated, for example, in - situ inside the processing chamber or in a remote plasma generator located away from the processing chamber. This processing is widely used to deposit materials on substrates to produce high - quality and high - performance semiconductor devices.

[0005] In the current semiconductor manufacturing industry, as the feature size continues to decrease, transistor structures are becoming increasingly complex and challenging. To meet the processing requirements, advanced process control techniques can be used to control costs and maximize the yield of substrates and dies. Typically, dies located at the edge of the substrate suffer from yield issues, such as contact due to misalignment and poor selectivity to hard masks. At the substrate processing level, there is a need to improve process uniformity control to allow for fine local process tuning and global process tuning across the entire substrate.

[0006] Accordingly, there is a need for methods and devices that allow for fine local process tuning at the edge of the substrate. The present technology addresses these and other needs. Summary of the invention

[0007] Embodiments of the present technology can allow for advantages in handling and processing substrates by using at least two bipolar electrodes and one annular electrode in a substrate support. The electrode configuration can allow for better tunability of ion flux near the wafer edge, which can result in higher uniformity of the deposited film. Additionally, the combination of the bipolar electrodes and the annular electrode can reduce the voltage required to electrostatically adsorb the wafer. The reduced voltage can result in fewer arc discharges and fewer wafer defects. Furthermore, embodiments of the present technology can reduce the impact of electrostatic charge on the wafer on the plasma. As a result, the plasma can be ignited after rather than simultaneously with wafer adsorption, and short - term plasma instabilities during plasma ignition can be reduced.

[0008] Embodiments of the present technology may include an electrostatic chuck. The chuck may include a top surface. The top surface may define a recessed portion of the chuck, and the recessed portion of the chuck may be configured to support a substrate. The recessed portion of the chuck may be characterized by a first diameter. The chuck may further include a first electrode and a second electrode. The first electrode and the second electrode may be disposed within the chuck. The first electrode and the second electrode may be substantially coplanar. The first electrode may be separated from the second electrode. Additionally, the chuck may include a third electrode. The third electrode may be disposed within the chuck. Furthermore, the third electrode may have an annular shape. The third electrode may be characterized by an inner diameter. The inner diameter may be greater than the first diameter. The third electrode may be separated from the first electrode and the second electrode. Additionally, the third electrode may be substantially parallel to the first electrode and the second electrode.

[0009] Embodiments of the present technology may include a plasma processing system. The plasma processing system may include an electrostatic chuck. The chuck may include any of the chucks disclosed herein. The system may further include a first power supply in electrical communication with the first electrode and the second electrode. The first electrode and the second electrode may be connected to the first power supply such that when the first power supply delivers a voltage to the first electrode, the first electrode and the second electrode have opposite voltages. The system may further include a second power supply in electrical communication with the third electrode.

[0010] Embodiments of the present technology may include a method of processing a substrate. The method may include disposing a substrate on an electrostatic chuck. The electrostatic chuck may include a first electrode, a second electrode, and a third electrode. The first electrode and the second electrode may be substantially coplanar. The third electrode may have an annular shape. The method may further include applying a first voltage to the first electrode. The method may further include applying a second voltage to the second electrode. The second voltage may be the opposite voltage of the first voltage. Additionally, the method may include applying a third voltage to the third electrode.

[0011] These and other specific embodiments, along with many of their advantages and features, will be described in more detail in conjunction with the following description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Reference may be made to the remainder of the specification and the drawings for a further understanding of the nature and advantages of the disclosed technology.

[0013] Figure 1 A cross-sectional schematic view of an exemplary processing chamber in accordance with some embodiments of the present technology is shown.

[0014] Figure 2A A top view of a substrate support assembly in accordance with some embodiments of the present technology is shown.

[0015] Figure 2B An electrical configuration of an electrode in accordance with some embodiments of the present technology is shown.

[0016] Figure 3 A partial perspective view of a substrate support assembly in accordance with some embodiments of the present technology is shown.

[0017] Figure 4 Exemplary operations in a processing substrate in accordance with some embodiments of the present technology are shown.

[0018] Several figures are included as schematic diagrams. It should be understood that the figures are for illustrative purposes and should not be considered to be to scale unless specifically stated to be so. Additionally, as schematic diagrams, the figures are provided to aid understanding and may not include all aspects or information compared to what is actually presented and may include exaggerated content for illustration.

[0019] In the figures, like components and / or features may have the same reference numerals. Furthermore, each of the same type of components may be distinguished by a letter following the reference numeral, which differentiates the similar components. If only the first reference numeral is used in the specification, the description thereof may apply to any of the similar components having the same first reference numeral, regardless of the suffix letter. DETAILED DESCRIPTION

[0020] As the feature sizes of semiconductor devices decrease, processing becomes more complex and results in additional challenges. Layers deposited near the edges of a substrate may not be as uniform as those near the center of the substrate. Non-uniformities near the wafer edge may cause the device to malfunction or perform poorly, thereby reducing yield and / or reliability. Wafers are typically not perfectly flat and are electrostatically chucked to reduce wafer bow. However, electrostatically chucking the wafer may create an arc on the backside of the wafer. Previously, when semiconductor devices were larger, arc discharges on the backside of the wafer may not have been a highly concerning issue, but processing for producing smaller devices sometimes includes materials deposited on the backside of the wafer. Such arc discharges may create defects on the backside of the wafer, which in turn may cause defects on the front side of the wafer. Additionally, conventionally electrostatically chucking the wafer may accumulate charge on the wafer and may affect plasma ignition and stability. As described below, embodiments of the present technology can overcome these challenges.

[0021] Figure 1 is a cross-sectional view of a processing chamber 100 in accordance with one or more embodiments. In one or more examples, the processing chamber 100 is a deposition chamber, such as a plasma enhanced chemical vapor deposition (PECVD) chamber, that is suitable for depositing one or more materials on a substrate such as substrate 154. In other examples, the processing chamber 100 is an etch chamber suitable for etching a substrate such as substrate 154. An example of a processing chamber that may be adapted to benefit from the exemplary aspects disclosed herein is Producer ®An etch processing chamber and a Precision™ processing chamber, which are commercially available from Applied Materials, Inc. located in Santa Clara, California. Other processing chambers can be contemplated, including those from other manufacturers, which can be adapted to benefit from the aspects disclosed herein.

[0022] Processing chamber 100 can be used for various plasma processes. In one aspect, processing chamber 100 can be used to perform dry etching with one or more etchants. For example, the processing chamber can be used to ignite a plasma from precursors such as one or more fluorocarbons (e.g., CF4 or C2F6), O2, NF3, or any combination thereof. In another embodiment, processing chamber 100 can be used for PECVD with one or more chemical reagents.

[0023] Processing chamber 100 can include a chamber body 102, a lid assembly 106, and a substrate support assembly 104. The lid assembly 106 can be positioned at the upper end of the chamber body 102. The lid assembly 106 and the substrate support assembly 104 can be used with any processing chamber for plasma or heat treatment. Other chambers available from any manufacturer can also be used with the above components. The substrate support assembly 104 can be disposed inside the chamber body 102, and the lid assembly 106 can be coupled to the chamber body 102 and enclose the substrate support assembly 104 in a processing space 120. The chamber body 102 includes a slit valve opening 126 formed in its sidewall. The slit valve opening 126 can be selectively opened and closed to allow entry by a substrate transfer robot (not shown) into the processing space 120 for substrate transfer.

[0024] The electrode 108 can be disposed adjacent to the chamber body 102 and can separate the chamber body 102 from other components of the lid assembly 106. The electrode 108 can be part of the lid assembly 106 or can be a separate sidewall electrode. The electrode 108 can be an annular or ring-shaped member, such as an annular electrode. The electrode 108 can be a continuous ring around the circumference of the processing chamber 100 surrounding the processing space 120, or can be discontinuous at selected locations if desired. The electrode 108 can also be a perforated electrode, such as a perforated ring or a mesh electrode. The electrode 108 can also be a plate-like electrode, such as a secondary gas distributor.

[0025] The isolator 110 contacts the electrode 108 and provides electrothermal isolation between the electrode 108 and the gas distributor 112 and the chamber body 102. The isolator 110 may be made of or include one or more dielectric materials. Exemplary dielectric materials may be or include one or more ceramics, metal oxides, metal nitrides, metal oxynitrides, silicon oxides, silicates, or any combination thereof. For example, the isolator 110 may be formed of or include alumina, aluminum nitride, aluminum oxynitride, or any combination thereof. The gas distributor 112 has an opening 118 for drawing a process gas into the processing space 120. The process gas may be supplied to the processing chamber 100 via one or more conduits 114, and the process gas may enter a gas mixing region 116 before flowing through one or more openings 118. The gas distributor 112 may be coupled to a power source 142, such as an RF generator. A DC power source, a pulsed DC power source, and a pulsed RF power source may also be used.

[0026] The substrate support assembly 104 may include a substrate support 180 that holds or supports one or more substrates 154 for processing. The substrate support 180 may be coupled to a lift mechanism by a shaft 144 that extends through the bottom surface of the chamber body 102. The lift mechanism may be flexibly sealed to the chamber body 102 by a bellows that prevents vacuum leakage around the shaft 144. The lift mechanism may allow the substrate support assembly 104 to move vertically within the chamber body 102 between a lower transfer position and a plurality of elevated processing positions.

[0027] The substrate support 180 may be formed of or include a metal or ceramic material. Exemplary metal or ceramic materials may be or include one or more metals, metal oxides, metal nitrides, metal oxynitrides, or any combination thereof. For example, the substrate support 180 may be formed of or include aluminum, alumina, aluminum nitride, aluminum oxynitride, or any combination thereof. The bipolar electrodes 122a and 122b may be coupled to the substrate support assembly 104. The bipolar electrodes 122a and 122b may be embedded within and / or coupled to the surface of the substrate support 180. Each of the bipolar electrodes 122a and 122b may be a plate, a perforated plate, a mesh, a wire mesh, or any other distributed arrangement.

[0028] Each of the bipolar electrodes 122a and 122b can be a tuned electrode and can be coupled to a tuning circuit 136 through a catheter 146, which is, for example, a cable with a selected resistance (such as 50 Ω) disposed in the shaft 144 of the substrate support assembly 104. The tuning circuit 136 can include an electronic sensor 138 and an electronic tuner or controller 140, which can be a variable capacitor. The electronic sensor 138 can be a voltage or current sensor and can be coupled to the electronic tuner or controller 140 to provide further control of the plasma conditions in the processing space 120. In one or more aspects, the electronic tuner or controller 140 can be used to modulate the impedance on the bipolar electrodes 122a and 122b.

[0029] Both bipolar electrodes 122a and 122b can be in electrical communication with the electronic sensor 138. In other embodiments, bipolar electrode 122a can be in electrical communication with the electronic sensor 138, and bipolar electrode 122b can be independently in electrical communication with a second electronic sensor and a second electronic tuner or controller, both of which can be the same as the electronic sensor 138 and the electronic tuner or controller 140. The bipolar electrodes 122a and 122b can be in electrical communication with a power source (not shown). The bipolar electrodes 122a and 122b can be bias electrodes and / or electrostatic chuck electrodes. The bipolar electrodes 122a and 122b can also be heaters for the substrate support 180.

[0030] The annular electrode 124 can be coupled to the substrate support assembly 104. The annular electrode 124 can be embedded within the substrate support 180. The bipolar electrodes 122a and 122b can be disposed above the upper portion of the annular electrode 124. In some examples, the annular electrode 124 is a bias electrode and / or an electrostatic chuck electrode. The annular electrode 124 can be coupled to a tuning circuit 156 through one or more cables or catheters 158 disposed in the shaft 144 of the substrate support assembly 104. The tuning circuit 156 can include a power source 150 and a processing controller 160 electrically coupled to the annular electrode 124.

[0031] For example, the power source 150 can be a power source of RF energy up to about 1000 W (but not limited to about 1000 W) at a frequency of, for example, about 13.56 MHz, but other frequencies and powers can be provided according to the needs of a particular application. The power source 150 can be capable of generating one or both of continuous or pulsed power. In one or more examples, the bias source can be a direct current (DC) or pulsed DC source. In other examples, the bias source may be capable of providing multiple frequencies, such as 2 MHz and 13.56 MHz.

[0032] The processing controller 160 may include a DC power supply 162, an RF generator 164, one or more electronic sensors 166, and one or more electronic tuners or controllers 168. The DC power supply 162 may supply voltage to the annular electrode 124, and the RF generator 164 may apply an RF frequency during plasma processing. The DC power supply 162 may supply and control a voltage from 0 V to about 1,000 V. In one or more aspects, the electronic tuner or controller 168 may be used to modulate the impedance on the annular electrode 124. For example, the electronic tuner or controller 168 may be used to control the impedance through a variable capacitor such that about 5% to about 95% of the impedance is controlled to the annular electrode 124. In some aspects, the electronic sensor 166 may be a voltage or current sensor and may be coupled to the electronic tuner or controller 168 to provide further control of the plasma conditions in the processing space 120.

[0033] Figure 2A A top view of a substrate support assembly 204 according to one or more embodiments is shown. The substrate support assembly 204 may be the substrate support assembly 104. The substrate support assembly 204 may include bipolar electrodes 222a and 222b, which may be the bipolar electrodes 122a and 122b. The bipolar electrodes 222a and 222b may be separated by a gap, which may be filled with an insulator. The insulator may be the body of the substrate support assembly 204. The width of the gap may be reduced or minimized. The width may be 0.01 to 0.05 inches, 0.05 to 0.1 inches, 0.1 to 0.25 inches, 0.25 to 0.5 inches, or 0.5 inches to 1.0 inches. The annular electrode 224 may be disposed below the bipolar electrodes 222a and 222b. The annular electrode 224 may be the annular electrode 124.

[0034] The bipolar electrodes 222a and 222b and the annular electrode 224 may be independently embedded or partially embedded in the substrate support 280. The substrate support 280 may be the substrate support 180. The bipolar electrodes 222a and 222b may be plates, perforated plates, meshes, wire meshes, or any other distributed arrangement. The bipolar electrodes 222a and 222b may be formed of or include one or more conductive metals or materials, such as aluminum, copper, their alloys, or any mixture thereof. The annular electrode 224 may be a ring. However, other shapes may be considered. The annular electrode 224 may be continuous or have spaced-through intervals. In some embodiments, the bipolar electrode 222a and the annular electrode 124 are cathodes.

[0035] In one or more examples, the combined surface area of bipolar electrodes 222a and 222b has a larger surface area than that of the annular electrode 224. In some examples, the outer diameter of the annular electrode 224 is greater than the diameters of the bipolar electrodes 222a and 222b. The annular electrode 224 may be formed of, or include, one or more conductive metals or materials, such as aluminum, copper, their alloys, or any mixture thereof. The annular electrode 224 may surround the bipolar electrodes 222a and 222b. In some embodiments, the annular electrode 224 at least partially overlaps the bipolar electrodes 222a and 222b.

[0036] As Figure 2B shown, the bipolar electrodes 222a and 222b and the annular electrode 224 may be coupled to separate power supplies. The annular electrode 225 may be coupled to the power supply 250. The bipolar electrodes 222a and 222b may be coupled to the power supply 270. The bipolar electrodes 222a and 222b may be configured to receive equal and opposite voltages from the power supply 270. The power supply 250 and the power supply 270 may independently be a DC power supply or an RF power supply, having any power, voltage, or frequency described herein, including Figure 1 any power, voltage, or frequency described in Figure 2B For clarity of illustration, Figure 2B the controllers, filters, tuners, or sensors that may be included in the power supplies 250 and 270 are not shown. However, any suitable controllers, filters, tuners, or sensors may be included.

[0037] Multiple bipolar electrodes 222a and 222b and the annular electrode 224 may be independently powered and controlled. The power distribution to the bipolar electrodes 222a and 222b may be a path separate from the power distribution path of the annular electrode 124. Thus, the path of the current may be shunted into different portions to facilitate a wider distribution, which may subsequently improve the uniformity of the treatment. Additionally, the vertical spacing between the annular electrode 224 and the bipolar electrodes 222a and 222b may extend the coupled power and may increase the treatment uniformity.

[0038] In some embodiments, the bipolar electrodes 222a and 222b may be used as adsorption electrodes while also being used as RF or DC electrodes. The annular electrode 224 may be an RF or DC electrode that, together with the bipolar electrodes 222a and 222b, may tune the plasma. The bipolar electrodes 222a and 222b and the annular electrode 224 may generate power at the same frequency or different frequencies.

[0039] In one or more embodiments, the RF power from one or both of power supplies 250 and 270 can be varied to tune the plasma. For example, a sensor (not shown) can be used to monitor the RF energy from any one or any combination of the bipolar electrodes 222a and 222b and the toroidal electrode 224. Data from the sensor device can be transmitted and used to vary the power applied to power supply 250 and / or power supply 270.

[0040] In another embodiment, a first impedance and / or voltage can be applied or otherwise provided to the bipolar electrodes 222a and 222b, and a second impedance and / or voltage can be independently applied or otherwise provided to the toroidal electrode 124. The parameters of the first impedance and / or voltage and the parameters of the second impedance and / or voltage can be independently monitored, controlled, and adjusted based on monitored parameters. Each of the first and / or second impedances can be independently increased and / or decreased, such as modulated, to improve the uniformity of the upper surface of the substrate. Also, each of the first and / or second voltages can be independently increased, decreased, modulated, or otherwise adjusted to improve the uniformity on the substrate surface.

[0041] In one or more examples, each of the first and / or second impedances and / or the first and / or second voltages can be modulated separately to reduce the in-plane distortion (IPD) of the uniformity of the substrate surface by 40% or more (relative to the IPD of the substrate surface before adjusting or modulating any impedance or voltage without changing the profile). For example, each of the first and / or second impedances and / or the first and / or second voltages can be independently modulated to reduce the IPD of the substrate surface uniformity by about 50%, about 60%, about 70% or more without changing the profile. In some examples, the IPD of the plasma uniformity can be reduced by about 40% to about 70% relative to the IPD of the substrate surface before adjusting or modulating any impedance or voltage without changing the profile.

[0042] In one embodiment, the bipolar electrodes 222a and 222b and the toroidal electrode 224 are powered simultaneously. In one embodiment, the bipolar electrodes 222a and 222b are turned on while the toroidal electrode 224 is turned off. In one embodiment, the bipolar electrodes 222a and 222b are turned off while the toroidal electrode 224 is turned on. Modulation between the powered bipolar electrodes 222a and 222b and the toroidal electrode 224 can help control the plasma characteristics at the edge of the substrate. Additionally, power supplies tuned separately to each of the toroidal electrode 224 and the bipolar electrodes 222a and 222b can result in an increased or decreased plasma density. Changing the voltage / current distribution on the bipolar electrodes 222a and 222b and the toroidal electrode 224 can facilitate the spatial distribution of the plasma on the substrate.

[0043] Figure 3 Depicts a partial perspective view of a substrate support assembly 304 including a substrate support 380 according to one or more embodiments. In this embodiment, the substrate 354 is positioned or otherwise disposed above the bipolar electrode 322b, which is above the annular electrode 324. The bipolar electrode 322b and the annular electrode 324 are shown horizontally overlapping each other. The substrate 354 is disposed within the recessed portion 306 of the substrate support 380. The annular electrode 324 is disposed within the substrate support 380 such that the annular electrode 324 circumferentially surrounds the substrate 354 and the recessed portion 306. The substrate support assembly 304, the substrate support 380, the bipolar electrode 322b, and the annular electrode 324 can be any similar components described herein, including those described in conjunction with Figure 1 , Figure 2A and Figure 2B together. Although only one bipolar electrode is shown, the substrate support assembly 304 can be symmetric about the diameter of the substrate support assembly 304, with a second bipolar electrode located on the other side of the substrate support assembly 304.

[0044] In Figure 3 various dimensions are shown. The distance 308 between the edge of the substrate 354 and the edge of the recessed portion 306 can be from 0.01 to 0.25 inches. The angle 310 with respect to the edge of the recessed portion 306 can be from 0 to 90 degrees. A larger vertical angle may increase undesirable ion scattering. The width 312 of the flat portion at the edge of the substrate support 380 can be from 0.25 to 1.23 inches. The distance 314 from the top of the substrate support 380 to the top of the annular electrode 324 can be from 0.01 to 0.3 inches. The height 316 from the top of the substrate support 380 to the recessed portion 306 can be from 0 to 0.25 inches. The lateral distance 318 from the edge of the substrate 354 to the annular electrode 324 can be from 0.005 to 0.2 inches. The overlap width 320 of the bipolar electrode 322b and the annular electrode 324 can be from -0.25 to 0.25 inches, including 0 inches. A negative overlap width 320 means that the bipolar electrode 322b and the annular electrode 324 do not overlap but are separated by a gap. Figure 3 The dimensions in

[0045] Benefits of the present technology can include enhanced control of the plasma adjacent edges of the substrate. The voltages or impedances to the three electrodes can be varied to control the plasma. The increased plasma control results in improved plasma uniformity. Controlling the power of the annular electrode can allow for more uniform deposition or etching at the edges of the substrate. The annular electrode can affect the ion flux at the wafer edge. Changing the impedance or capacitance of the annular electrode can also change the impedance of the plasma. At certain voltages, the uniformity at the wafer edge can be improved. The average thickness range of the deposited film at positions in the range of 135 mm to 148 mm (0 mm being the center of the wafer) as a percentage of the thickness relative to the center of the wafer can be 1% to 2%, 2% to 3%, or 3% to 4%.

[0046] Additionally, embodiments of the present technology can reduce the adsorption voltage, which can reduce arcing and also reduce backside damage to the wafer. Using three electrodes (two bipolar electrodes and one annular electrode) can lower the adsorption voltage. The adsorption voltage when using two bipolar electrodes and one annular electrode was found to reduce the minimum adsorption voltage required before the onset of plasma impedance instability. For example, for a monopolar electrode and an annular electrode, plasma impedance instability is observed at voltages of 600 V and lower. In contrast, for bipolar electrodes and an annular electrode, plasma impedance instability is observed at voltages of 200 V and lower. Since the annular electrode can act as a limiting ring to reduce leakage current from the bipolar electrodes, a lower adsorption voltage can be achieved.

[0047] To provide a certain margin on the voltage at which plasma impedance is observed, the minimum adsorption voltage of the bipolar electrode can be set to ±300 V, while the minimum adsorption voltage of the monopolar electrode can be set to -700 V, as an example. The adsorption voltage can be reduced by more than 50%, which unexpectedly is greater than what would be expected by adding another electrode for electrostatic adsorption. In some embodiments, when using bipolar electrodes with a ring electrode, the adsorption voltage can be reduced by 30% to 40%, 40% to 50%, 50% to 60%, 60% to 70%, 70% to 80%, or 80% to 90% compared to a monopolar electrode or a monopolar electrode with a ring electrode. Reducing the adsorption voltage can reduce arcing on the backside of the wafer, which can reduce wafer defects. In some cases, the backside of the wafer can have a deposited film that may be damaged due to arcing on the surface of the substrate support. Reducing the adsorption voltage can also reduce operating costs and increase the lifespan of the equipment, including any part of the substrate support assembly described herein. In certain cases, the adsorption voltage of the bipolar electrode can be the same or close to that of the monopolar electrode, but the area of the bipolar electrode can be reduced. For example, the total area of the bipolar electrode can be 50% to 60%, 60% to 70%, 70% to 80%, 80% to 90%, or 90% to 95% of the substrate area.

[0048] Another advantage of some embodiments of the present technology is the ability to turn on the plasma after electrostatically adsorbing the substrate to the substrate support. In a system with a monopolar electrode, electrostatically adsorbing the wafer charges the wafer, which can affect the plasma with a positive charge. Turning on the plasma while adsorbing the wafer may cause an instantaneous plasma effect, which may have a negative impact on the processing of the substrate. In embodiments of the present technology, the bipolar electrode equalizes the charging of the wafer, thereby reducing the influence of the wafer on the electrostatic chuck in the plasma.

[0049] Embodiments of the present technology may include an electrostatic chuck. The chuck may be the substrate support assembly 104, the substrate support assembly 204, or the substrate support assembly 304. The chuck may include a top surface. The top surface may define a recessed portion of the chuck (e.g., the recessed portion 306). The recessed portion of the chuck may be configured to support the substrate. The substrate may be a semiconductor wafer, including a silicon wafer or a silicon-on-insulator wafer. The substrate may be the substrate 154 or the substrate 354. The recessed portion of the chuck may be substantially flat. The recessed portion of the chuck may be circular and may be characterized by a first diameter. The first diameter may be greater than the diameter of the substrate, and the substrate may be located within the recessed portion.

[0050] The chuck may further include an insulator. The insulator may be the body of the chuck. The insulator may include any metal, ceramic material, or insulating material described herein. By way of example, the insulator may include alumina. In some embodiments, within the body of the chuck, the insulator may be air or a vacuum.

[0051] The chuck may further include a first electrode and a second electrode. The first electrode and the second electrode may be any bipolar electrode described herein, including, for example, the bipolar electrodes 122a, 122b, 222a, and 222b. The first electrode and the second electrode may be substantially coplanar. For example, the first electrode and the second electrode may be at the same vertical height, which height is along a line orthogonal to the substrate supported by the chuck. The first electrode may be separated from the second electrode. The first electrode and the second electrode may be separated by an insulator. For example, in Figure 2A the bipolar electrodes 222a and 222b are separated by a uniform gap. Even in Figure 2A the insulator is not shown, the uniform gap may be an insulator. The first electrode and the second electrode may include a mesh or any material described herein. The mesh may be preferred over a plate because less charge can accumulate in the mesh, which can reduce arcing, processing, and other problems when the electrodes discharge when the substrate is desorbed.

[0052] The first electrode and the second electrode may have substantially the same surface area. The first electrode may be substantially semi-circular. The second electrode may be substantially semi-circular. For example, if the first electrode and the second electrode are in contact with each other along a straight edge, the first electrode and the second electrode may form a circle or a substantially circular shape.

[0053] The first electrode and the second electrode may be characterized by a second diameter. For example, the second diameter may be the diameter of the smallest circle circumscribing the first electrode and the second electrode disposed in the suction cup. The second diameter may be greater than the first diameter of the recessed portion.

[0054] The first electrode may be configured such that when the substrate is disposed in the recessed portion and a first voltage is applied to the first electrode, a first electrostatic force holds the substrate on the suction cup. The second electrode may be configured such that when the substrate is disposed in the recessed portion and a second voltage is applied to the second electrode, a second electrostatic force holds the substrate to the suction cup. The second voltage may have a polarity opposite to that of the first voltage. The first voltage may have the same magnitude as the second voltage, but may be negative instead of positive.

[0055] In some embodiments, the suction cup may include one or more electrodes in addition to the first electrode and the second electrode. Each of the first electrode, the second electrode, and the one or more electrodes may have substantially the same area. The same area may allow an equal amount of positive and negative charges on the substrate, so that the charges have an equal force on the substrate to fix the substrate. The outer edges of the first electrode, the second electrode, and the one or more electrodes may depict the circumference of a circle. For example, each electrode may be a sector of a circle. In general, the suction cup may include 2, 4, 6, or 8 sectors of a circle as electrodes.

[0056] Additionally, the suction cup may include a third electrode. The third electrode may have an annular shape. The third electrode may include any of the annular electrodes described herein, including, for example, annular electrode 124, annular electrode 224, or annular electrode 324. The third electrode may be characterized by an inner diameter, where the inner diameter characterizes the circular hole within the ring of the third electrode. The inner diameter may be greater than the first diameter of the recessed portion. The inner diameter may be less than the second diameter of the first electrode and the second electrode. The third electrode may be separated from the first electrode and the second electrode. An insulator may separate the third electrode from the first electrode and the second electrode.

[0057] The third electrode may be characterized by an outer diameter. The outer diameter may be the diameter of the smallest circle circumscribing the third electrode. The outer diameter may be greater than the second diameter of the first electrode and the second electrode.

[0058] The third electrode may be substantially parallel to the first and second electrodes. The third electrode may be disposed further away from the top surface than the first electrode. The third electrode may be below the substrate, the first electrode, and the second electrode. The third electrode below the substrate may reduce arcing to the substrate. Specifically, if the third electrode is above the substrate in a non-recessed portion of the substrate support, some arcing may occur at the edge of the substrate. The third electrode may include a mesh or any material described herein.

[0059] Embodiments of the present technology may include a plasma processing system. The plasma processing system may include an electrostatic chuck, which may be any chuck described herein. The system may include a first power supply in electrical communication with the first and second electrodes. The first power supply may be power supply 270. The first and second electrodes may be connected to the first power supply such that when the first power supply delivers a voltage to the first electrode, the first and second electrodes have opposite voltages. The first power supply may be a DC power supply or an RF power supply. The system may further include a second power supply in electrical communication with the third electrode. The second power supply may be an RF power supply or a DC power supply.

[0060] In some embodiments, the plasma processing system may include a computer system. The computer system may include a non-transitory computer-readable medium storing a plurality of instructions. The plurality of instructions may include any method described herein, including method 400 described below. One or more processors may execute the instructions by sending commands to components of the plasma processing system. Components of the plasma processing system may include a substrate handling robot to move the substrate into processing, onto the chuck, off the chuck, and out of the processing area.

[0061] Figure 4 Exemplary operations of a method 400 for processing a substrate according to some embodiments of the present technology are shown. Method 400 may include using any chuck or system described herein.

[0062] At block 402, method 400 may include setting a substrate on an electrostatic chuck. The electrostatic chuck may be any electrostatic chuck described herein, including substrate support assembly 104, substrate support assembly 204, or substrate support assembly 304. The electrostatic chuck may include a first electrode, a second electrode, and a third electrode. The first and second electrodes may be substantially coplanar. The third electrode may have an annular shape. The electrodes may be any electrodes described herein.

[0063] At block 404, method 400 may include applying a first voltage to a first electrode. The first voltage may be a direct current (DC) voltage or a radio frequency (RF) voltage. If the first voltage is a DC voltage, the first voltage may have a magnitude of 50 V to 100 V, 100 V to 200 V, 200 V to 300 V, or 300 V to 400 V. If the first voltage is an RF voltage, the first voltage may have a maximum voltage of 50 V to 100 V, 100 V to 200 V, 200 V to 300 V, or 300 V to 400 V.

[0064] At block 406, method 400 may include applying a second voltage to a second electrode. The second voltage may be a voltage opposite to the first voltage. For example, if the first voltage is positive, the second voltage is negative and has the same magnitude. In some embodiments, the second voltage may have a magnitude different from that of the first voltage. If the second voltage is RF, the second voltage may be instantaneously opposite to the first voltage, and the second average voltage may be the same as the first average voltage.

[0065] At block 408, method 400 may include applying a third voltage to a third electrode. The third voltage may be an RF voltage. The ratio of the magnitude of the applied maximum third voltage to the magnitude of the applied maximum first voltage may be 0.1 to 0.5, 0.5 to 1.0, 1.0 to 1.5, 1.5 to 2.0, 2.0 to 3.0, or 3.0 or greater.

[0066] Additionally, method 400 may include heating the electrostatic chuck to a temperature of 500 °C to 600 °C, 600 °C to 700 °C, or greater than 700 °C. Method 400 may further include forming a plasma in the processing region. The plasma may be formed after applying power to the bipolar electrode. A substrate may be disposed in the processing region. Method 400 may include extinguishing the plasma and removing the substrate from the processing region and the plasma processing system.

[0067] The bipolar electrode and the annular electrode may be used to tune the plasma. In one or more embodiments, a method for adjusting the plasma in a chamber may include applying a first radio frequency (RF) power to the bipolar electrode and applying a second RF power to the annular electrode. The method may further include monitoring parameters of the first and second RF powers and adjusting one or both of the first and second RF powers based on the monitored parameters.

[0068] In other embodiments, a method for regulating a plasma in a chamber may include applying a first impedance, a first voltage, or a combination of the first impedance and voltage to a bipolar electrode, and applying a second impedance, a second voltage, or a combination of the second impedance and voltage to an annular electrode. The method may further include monitoring one or more parameters of the first impedance, the second impedance, the first voltage, the second voltage, or any combination thereof, and regulating one or more of the first impedance, the second impedance, the first voltage, the second voltage, or any combination thereof based on the monitored parameters.

[0069] In the foregoing description, for purposes of explanation, numerous details are set forth in order to provide an understanding of the various embodiments of the present technology. However, it will be apparent to one of ordinary skill in the art that some of these specific details may not be required for the practice of a particular embodiment (or additional details may be required).

[0070] After several embodiments have been disclosed, one of ordinary skill in the art will appreciate that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the disclosed embodiments. Additionally, some well-known processes and elements have not been described in order to avoid unnecessarily obscuring the present technology. Accordingly, the foregoing description should not be regarded as limiting the scope of the technology. Additionally, a method or process may be described as sequential or stepwise, but it should be understood that the operations may be performed concurrently or in a different order than that listed.

[0071] In the case of providing a series of values, it should be understood that, unless the context clearly dictates otherwise, each intermediate value between the upper and lower limits of this range is also specifically disclosed, to the smallest part of the unit of the lower limit. Any stated value or intervening value within the range, and any narrower range between any other stated or intervening value within the range, is included. The upper and lower limits of these smaller ranges may independently be included within or excluded from the range, and each range that includes one, both, or neither of the upper and lower limits is also included within the present technology and is subject to any specific exclusions of the stated range. When the stated range includes one or both of the upper and lower limits, ranges excluding either or both of these limits are also included.

[0072] As used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "an electrode" includes a plurality of such electrodes, and reference to "a power supply" includes one or more power supplies known to those of ordinary skill in the art and their equivalents, and so forth.

[0073] Furthermore, as used in this specification and the appended claims, the words "comprise(s)", "comprising", "contain(s)", "containing", "include(s)" and "including" are intended to specify the presence of the stated features, integers, components, or operations, but they do not preclude the presence or addition of one or more other features, integers, components, operations, acts, or groups.

Claims

1. An electrostatic chuck, the chuck comprising: A top surface, wherein: The top surface defines a recessed portion of the chuck, the recessed portion of the chuck being configured to support a substrate, and The recessed portion of the chuck is characterized by a first diameter; A first bipolar adsorption electrode and a second bipolar adsorption electrode disposed within the chuck, wherein: The first bipolar adsorption electrode and the second bipolar adsorption electrode are substantially coplanar semi - circles, the coplanar semi - circles being separated by a straight gap along a straight edge of the coplanar semi - circles; and A third adsorption electrode disposed within the chuck, wherein: The third adsorption electrode includes a ring characterized by an inner diameter, the inner diameter defining the innermost edge of the third adsorption electrode; The inner diameter is greater than the first diameter; A top portion of the third adsorption electrode is disposed below the first bipolar adsorption electrode and the second bipolar adsorption electrode and partially overlaps with the first bipolar adsorption electrode and the second bipolar adsorption electrode below the first bipolar adsorption electrode and the second bipolar adsorption electrode; and The third adsorption electrode is substantially parallel to the first bipolar adsorption electrode and the second bipolar adsorption electrode, Wherein the first bipolar adsorption electrode is configured such that when the substrate is disposed in the recessed portion and a first voltage is applied to the first bipolar adsorption electrode, a first electrostatic force holds the substrate on the chuck; The second bipolar adsorption electrode is configured such that when the substrate is disposed in the recessed portion and a second voltage is applied to the second bipolar adsorption electrode, a second electrostatic force holds the substrate on the chuck, the second voltage having a polarity opposite to that of the first voltage; The first bipolar adsorption electrode, the second bipolar adsorption electrode, and the third adsorption electrode are configured to be used as DC adsorption electrodes and as RF electrodes for modulating a plasma.

2. The chuck according to claim 1, wherein the first bipolar adsorption electrode and the second bipolar adsorption electrode have substantially the same surface area, and the third adsorption electrode does not separate the first bipolar adsorption electrode and the second bipolar adsorption electrode.

3. The chuck according to claim 1, wherein: The first bipolar adsorption electrode includes a mesh; The second bipolar adsorption electrode includes a mesh; and The third adsorption electrode includes a mesh.

4. The chuck according to claim 1, wherein: The third adsorption electrode does not vertically extend above the recessed portion of the chuck and does not horizontally extend below the recessed portion of the chuck.

5. The chuck according to claim 1, wherein the top portion of the third adsorption electrode is disposed between 0.01 inches and 0.30 inches from the top surface outside the recessed portion.

6. The chuck according to claim 1, wherein: The first bipolar adsorption electrode and the second bipolar adsorption electrode are characterized by a second diameter, and The second diameter is greater than the inner diameter.

7. The chuck according to claim 6, wherein: The third adsorption electrode is also characterized by an outer diameter, and The outer diameter is greater than the second diameter.

8. The chuck according to claim 1, wherein the third adsorption electrode serves as a limiting ring, and the limiting ring reduces the leakage current from the first bipolar adsorption electrode and the second bipolar adsorption electrode when adsorbing the substrate.

9. The chuck according to claim 1, wherein: the first bipolar adsorption electrode and the second bipolar adsorption electrode are also configured to serve as heaters for the recessed portion of the chuck.

10. The chuck according to claim 1, further comprising: a first tuning circuit in electrical communication with the first bipolar adsorption electrode and the second bipolar adsorption electrode; and a second tuning circuit in electrical communication with the third adsorption electrode, wherein the first tuning circuit and the second tuning circuit are configured to modulate the RF power between the first bipolar adsorption electrode, the second bipolar adsorption electrode, and the third adsorption electrode.

11. The chuck according to claim 1, further comprising: a connection for the positive electrical output of the first bipolar adsorption electrode to a first DC electrostatic adsorption source; a connection for the negative electrical output of the second bipolar adsorption electrode to a first DC electrostatic adsorption source; and a connection for the third adsorption electrode to a second DC electrostatic adsorption source.

12. The chuck according to claim 11, wherein the maximum adsorption voltage for the first DC electrostatic adsorption source is set to -300V, and the maximum adsorption voltage for the second DC electrostatic adsorption source is set to +300V.

13. The chuck according to claim 12, wherein the minimum adsorption voltage is reduced by more than 50% from the adsorption voltage without the third adsorption electrode.

14. The chuck according to claim 1, wherein the first bipolar adsorption electrode and the second bipolar adsorption electrode are symmetric with respect to the straight gap separating the first bipolar adsorption electrode and the second bipolar adsorption electrode.

15. The chuck according to claim 1, wherein the distance between the edge of the substrate and the edge of the recessed portion is between 0.01 inches and 0.25 inches.

16. The chuck according to claim 1, wherein the angle from the edge of the recessed portion to the top portion of the top surface is 90 degrees.

17. The chuck according to claim 1, wherein the straight gap is uniform along the straight edge of the coplanar semi-circle.

18. The chuck according to claim 1, wherein the outer edges of the first bipolar adsorption electrode and the outer edges of the second bipolar adsorption electrode depict the circumference of a circle.

19. The chuck according to claim 1, wherein the combined surface area of the first bipolar adsorption electrode and the second bipolar adsorption electrode has a larger surface area than the third adsorption electrode.

20. The chuck according to claim 1, wherein the first bipolar adsorption electrode, the second bipolar adsorption electrode, and the third adsorption electrode are configured to serve as DC adsorption electrodes and as RF electrodes for modulating plasma.

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