Power supply signal conditioning for electrostatic chucks

Abstract

Exemplary semiconductor processing systems may include a processing chamber and an electrostatic chuck disposed at least partially within the processing chamber. The electrostatic chuck may include at least one electrode and a heater. The semiconductor processing system may include a power supply for providing a signal to the electrode to provide an electrostatic force for securing a substrate to the electrostatic chuck. The system may also include a filter communically coupled between the power supply and the electrode. The filter is configured to eliminate or reduce noise introduced into the chucking signal by operating the heater while the electrostatic force is maintained on the substrate. The filter may include an active circuit, a passive circuit, or both, and may include an adjustment circuit that sets the gain of the filter such that the output signal level from the filter corresponds to the input signal level for the filter.

Description

Technology Field

[0001] This application claims the benefit and priority of U.S. Patent Application No. 17 / 036,048, filed September 29, 2020, with the title of the invention "POWER SUPPLY SIGNAL CONDITIONING FOR AN ELECTROSTATIC CHUCK", which is incorporated herein by reference in its entirety.

[0002] The present technology relates to components and devices for semiconductor manufacturing. More specifically, the present technology relates to electrostatic chucking components and other semiconductor processing equipment. Background Technology

[0003] Integrated circuits are made possible by processes that create complexly patterned material layers on substrate surfaces. Creating patterned materials on a substrate requires controlled methods for the formation and removal of exposed materials. As device sizes continue to shrink, deposited materials can impart stresses to the substrates, which can lead to substrate warping. During subsequent deposition operations, wafer warping can affect contact across the substrate support, which can affect heating. Non-uniform heating profiles across the substrate can affect subsequent deposition operations, causing non-uniform deposition across the substrate surface.

[0004] Therefore, improved systems and methods that can be used to produce high-quality devices and structures are required. These and other requirements are addressed by the present technology.

[0005] Exemplary semiconductor processing systems may include a processing chamber and an electrostatic chuck disposed at least partially within the processing chamber. The electrostatic chuck may include at least one electrode and a heater. The semiconductor processing system may include a power supply for providing a signal to the electrode to provide an electrostatic force for securing a substrate to the electrostatic chuck. The semiconductor processing system may also include a filter communically coupled between the power supply and the electrode. The filter is configured to remove noise introduced by operating the heater while the electrostatic force is maintained on the substrate.

[0006] In some embodiments, the filter may include a passive circuit comprising a plurality of resistors and capacitors, an inductor, or both. The filter may include a circuit configured to provide at least 40 dB of attenuation at a designed frequency of 45 Hz to 65 Hz while the heater maintains the temperature of the substrate at 550°C to 650°C. The filter may include a twin-T band rejection circuit, and the first T-circuit includes at least one resistor having a resistance value approximately twice the resistance value of the resistor in the second T-circuit and a capacitor having a capacitance value approximately twice the capacitance value of at least one capacitor in the second T-circuit. The filter may include both a passive stage and an active stage. The active stage may include an operational amplifier and an adjustment circuit communicably coupled to the operational amplifier to set the gain of the filter so that the output signal level from the filter corresponds to the input signal level for the filter.

[0007] Some embodiments of the present technology include semiconductor processing methods. The methods may include the step of applying a chucking voltage to an electrostatic chuck supporting a substrate in a semiconductor processing chamber, and the step of energizing a heater to raise the temperature of the substrate. The methods may also include the step of filtering a power supply signal providing the chucking voltage to remove noise introduced into the power supply signal by the heater while the electrostatic force on the substrate is maintained. The methods may further include the step of setting a gain applied to the power supply signal during filtering so that the output signal level corresponds to the input signal level. The methods may also include the step of processing the substrate in a semiconductor processing chamber. In some embodiments, filtering may be achieved using one or more of the aforementioned filter circuits and configurations.

[0008] Exemplary power supply systems may include a power supply configured to provide a signal to an electrode within an electrostatic chuck, and a filter communically coupled to the power supply. The filter is configured to remove incoming noise by operating a heater within the electrostatic chuck while the electrostatic force on the substrate is maintained. The filter may include an operational amplifier, and a control circuit communically coupled to the operational amplifier to set the gain of the filter so that the output signal level from the filter corresponds to the input signal level. The filter may include any of the filtering circuits and configurations discussed above. In some embodiments, the power supply mentioned as part of the exemplary power supply systems and / or as part of the exemplary semiconductor processing systems may be configured to provide a voltage that varies over time as a square wave with a frequency of about 20 Hz, a duty cycle of about 20%, a magnitude of about + / - 1000 V, and a substantially 0 V offset. Brief explanation of the drawing

[0009] Further understanding of the nature and advantages of the disclosed technology can be realized by referring to the remainder of the specification and the drawings.

[0010] FIG. 1 illustrates a schematic cross-sectional view of an exemplary processing system according to some embodiments of the present technology.

[0011] FIG. 2 illustrates a schematic cross-sectional view of an exemplary electrostatic chuck and an exemplary power supply system according to some embodiments of the present technology.

[0012] FIG. 3 illustrates a schematic diagram of an exemplary filter circuit according to some embodiments of the present technology.

[0013] FIG. 4 illustrates a schematic diagram of another exemplary filter circuit according to some embodiments of the present technology.

[0014] FIG. 5 illustrates a schematic diagram of an additional exemplary filter circuit according to some embodiments of the present technology.

[0015] FIG. 6 illustrates a flowchart of a method for supplying power to the electrodes of an electrostatic chuck according to some embodiments of the present technology.

[0016] FIG. 7 illustrates a chart illustrating the effects of filtering power supplied to an electrostatic chuck according to some embodiments of the present technology.

[0017] Some of the drawings are included as schematics. It should be understood that the drawings are for illustrative purposes only and should not be considered to be in scale unless specifically stated otherwise. Additionally, as they are schematic in nature, the drawings are provided for illustrative purposes only and may not include all modes or information compared to realistic representations. The drawings may include exaggerated materials for illustrative purposes.

[0018] In the attached drawings, similar components and / or features may have the same reference label. Additionally, electronic components of the same type may be distinguished by letters and numbers, and numbers distinguish similar components. Specific details for implementing the invention

[0019] Many material deposition processes can be temperature-sensitive. In various processing systems, the substrate support can act as a heat source for the substrate during deposition. As manufacturing processes are performed, multiple layers of material may be formed on the substrate, which can impart multiple stresses to the substrate. In many cases, these stresses can cause a certain amount of warping of the substrate. Chucking by an electrostatic chuck (ESC) can counteract multiple warping effects to maintain a flatter substrate, which can maintain more uniform contact across the substrate support, which ultimately allows for more uniform heating across the substrate.

[0020] When ceramic heaters within a processing chamber operate at high temperatures, they are semiconductive. For example, the resistance of aluminum nitride ceramic materials can drop to approximately 20 kΩ when carrying current to ground through the wafer and ESC surfaces. This reduced resistance can create a noise path between the heater and the chucking power supply system components. Heater elements typically carry AC voltage and current of, for example, 208 VAC RMS at 60 Hz. The AC voltage and current flowing through parts of the semiconductive materials are coupled through the ESC electrodes and the ESC power supply, which can affect the regulation of the power supply. Parts of the AC power, voltage, and current used for the heater elements overlap with the peaks of the chucking voltage and current, potentially causing poor chucking power supply regulation, which can lead to perturbations in the chucking force. Such perturbations can eventually result in unintended deformation of the substrate and consequent deposition defects.

[0021] This technology overcomes these challenges by utilizing one or more chucking power conditioning mechanisms to eliminate unwanted voltage and current noise in the chucking power. For example, a filter may be provided. The filter is configured to eliminate or reduce noise introduced into the chucking signal by operating a heater. The filter may include an active circuit, a passive circuit, or both, and may include a control circuit for setting the gain of the filter so that the output signal level from the filter corresponds to the input signal level for the filter. Thus, improved film formation and removal, as well as improved film properties, can be provided.

[0022] While the remainder of the disclosure will routinely identify specific deposition processes utilizing the disclosed technology, it will be readily understood that the systems and methods are equally applicable to processes that may occur in the described chambers as well as other deposition and cleaning chambers. Accordingly, the present technology should not be construed as being limited to use only in these specific deposition processes or chambers. Before further variations and adjustments to the system according to the embodiments of the present technology are described, the present disclosure will discuss one possible system and chamber that may include cover stack components according to the embodiments of the present technology.

[0023] FIG. 1 illustrates a schematic cross-sectional view of an exemplary semiconductor processing system according to some embodiments of the present technology. As illustrated, the processing system (100) may be an etching chamber suitable for etching a substrate (121). The processing system (100) may be used for various plasma processes. For example, the processing system (100) may be used to perform dry etching with one or more etchants. The processing system uses a precursor C x F y (Here, x and y represent values ​​for known compounds), can be used for ignition of plasma from O2, NF3, or combinations thereof. In another example, the processing chamber (100) can be used for a plasma-enhanced chemical vapor deposition (PECVD) process using one or more precursors.

[0024] The system comprises a processing chamber (120) having a chamber body (102), a cover assembly (106), and an electrostatic chuck (101). The electrostatic chuck (101) comprises a support stem (107) and a chuck body (228). A portion of the support stem may protrude from the chamber, but the electrostatic chuck is contained at least partially within the processing chamber during operation. The cover assembly (106) is positioned at the upper end of the chamber body (102). The chuck body (228) may be contained within the chamber body (102), and the cover assembly (106) may be coupled to the chamber body (102) and enclose the chuck body (228) within the processing chamber. The chamber body (102) may include a transfer port (126) formed within the side wall of the chamber body (102), which may include a slit valve. The transfer port (126) can be optionally opened and closed to allow access into the interior of the processing chamber (120) by a substrate handling robot (not shown) for substrate transfer.

[0025] The electrode (108) may be provided as part of the cover assembly (106). The electrode (108) may also function as a gas distributor plate (112) having a plurality of openings (118) for introducing process gases into the interior of the processing chamber (120). Process gases may be supplied to the processing chamber (120) through the conduit (114), and the process gases may enter the gas mixing area (116) before flowing through the openings (118). The electrode (108) may be coupled to a source of electric power, such as an RF generator (109). An isolator (110) may contact the electrode (108) and electrically and thermally isolate the electrode (108) from the chamber body (102). The isolator (110) may be constructed using a dielectric material such as aluminum oxide, aluminum nitride, and / or other ceramics or metal oxides. The heater (119) can be coupled to the gas distributor plate (112). The heater (119) can also be coupled to an AC power source (not shown).

[0026] The chuck body (104) may be formed of a metal or ceramic material. For example, metal oxides, nitrides, or oxide / nitride mixtures such as aluminum, aluminum oxide, aluminum nitride, aluminum oxide / nitride mixtures, and / or other similar materials may be used. In typical embodiments, one or more pedestal electrodes may be included in the chuck body (104). One or more pedestal electrodes (not shown) may be configured to deliver RF energy to the plasma inside the processing chamber (120).

[0027] The electrostatic chuck (101) is configured to support and hold a substrate being processed. In one embodiment, the electrostatic chuck (101) may include at least one electrode (223) to which voltage is applied to electrostatically fix a substrate thereon. The electrode (223) is powered by a power supply unit (276) connected to the electrode (223) through an interface circuit unit (177). The electrostatic chuck (101) may be unipolar, bipolar, tripolar, DC, interdigitated, zonal, etc.

[0028] In one embodiment, the electrostatic chuck (101) may include heating elements, such as resistive elements, to heat a substrate positioned thereon to a desired process temperature. Alternatively, the electrostatic chuck (101) may be heated by an external heating element, such as a lamp assembly. An RF source (109) is coupled to an electrode (108) through an impedance matching circuit (173). The electrode (223) may provide both a ground path to the RF source (109) and an electric bias from a power supply (276) to enable electrostatic clamping of the substrate (121).

[0029] The RF source (109) may include a high-frequency radio frequency (HFRF) power supply, e.g., a 13.56 MHz RF generator, and a low-frequency radio frequency (LFRF) power supply, e.g., a 300 kHz RF generator. The LFRF power supply provides both low-frequency generating and fixed-match elements. The HFRF power supply is designed to be used with fixed-match and regulates the power delivered to the load, thereby eliminating concerns regarding forward and reflected power.

[0030] In certain embodiments, the properties of the substrate (121) fixed on the chuck body (104) can be monitored during the plasma process. In certain embodiments, the properties can be monitored by measuring the characteristics of the electrostatic chuck (101) on which the substrate is fixed. The characteristics of the electrostatic chuck (101) can be measured by a sensor (174) connected to the divider plate (112). The sensor (174) may be a VI probe connected between the divider plate (112) and an impedance matching circuit (173). In some embodiments, the sensor (174) may be configured to measure the capacitance between the divider plate (112) and the electrode (223), because the capacitance between the divider plate (112) and the electrode (223) is affected by the flatness of the substrate (121). The electrostatic chuck may have increased capacitive reactance when the substrate placed thereon becomes less flat. When the substrate is not flat, for example, when deformed by the heat of the plasma, there is an uneven distribution of air gaps between the substrate and the electrostatic chuck. Therefore, variations in the flatness of the substrate within the electrostatic chuck cause variations in the capacitance of the plasma reactor that can be measured. In such cases, the sensor (174) may be configured to monitor the flatness of the substrate fixed thereon by measuring the impedance of the electrostatic chuck (101) by measuring the voltage and current of the capacitor formed by the distributor plate (112) and the electrode (223).

[0031] During the plasma process, the curvature of a substrate positioned on an electrostatic chuck may increase due to deformation from heating, increased thickness of the deposited film, loss of chucking power, or a combination thereof. Deformation of the substrate may increase non-uniformity of the process. In one embodiment, the flatness of the substrate being processed may be monitored by measuring the characteristics of the electrostatic chuck holding the substrate. According to predetermined conditions, the chucking voltage of the electrostatic chuck may be adjusted to correct the substrate deformation. The sensor (174) may be connected to a system controller (175). The system controller (175) may be configured to calculate and adjust the flatness of the substrate (121) being processed in the system (100). In one embodiment, the system controller (175) may calculate the flatness or chucking state of the substrate (121) by monitoring the characteristics of the electrostatic chuck (101), such as virtual impedance. When measuring the impedance indicates that the flatness of the substrate (121) is reduced, the system controller (175) can increase the chucking power by adjusting the power supply (276).

[0032] FIG. 2 illustrates a schematic cross-sectional view of an exemplary electrostatic chuck according to some embodiments of the present technology. The electrostatic chuck (200) comprises a chuck body (228) coupled to a support stem (226). The body (228) has a top surface (202) configured to provide support and clamping to a substrate (121) during processing. The body (228) of the electrostatic chuck (200) comprises an electrode (223) coupled to a conductive member (286). The electrode (223) may be a metal electrode of a size comparable to the substrate inside the body (228) and may be constructed to be substantially parallel to the substrate (121) to be held against the top surface (202) of the body (228). The electrode (223) may be arranged in any configuration or pattern so that the electrodes are evenly distributed across the top surface (202). For example, the electrode (223) may be arranged in a grid, pixel, or dot configuration. The conductive member (286) may be a rod, tube, wire, etc., and may be made of a conductive material, such as molybdenum (Mo), tungsten (W), or other material having a coefficient of expansion substantially similar to that of the body (228). In some embodiments, the top surface (202) of the body (228) may have various patterns of surface contacts (290) that may be arranged close to and / or in contact with the rear area of ​​the substrate (121) to affect the chucking force and timing performance.

[0033] In one embodiment, the electrostatic chuck uses a single electrode (223) to maintain a substantially uniform voltage between the electrode (223) and the substrate (121). Alternatively, the electrostatic chuck may use a bipolar ESC in which multiple chucking electrodes having different voltages are used to generate a clamping force. In some embodiments, the electrostatic chuck (200) may have a biasing electrode embedded in or placed in the body (228) to provide an electric bias to the substrate to facilitate or increase electrostatic clamping of the substrate. Alternatively, the electrode (223) may provide both a ground path for radio frequency (RF) power (e.g., RF source (109) of FIG. 1) and an electric bias to the substrate (121) to enable electrostatic clamping of the substrate.

[0034] To provide an electric bias to the substrate (121), the electrode (223) may communicate with a power supply system (280) that supplies a biasing voltage to the electrode (223). The power supply system (280) includes a power supply unit (276) which may be a direct current (DC) power source for supplying a DC signal to the electrode (223). In one embodiment, the power supply unit (276) is a 24V DC power supply unit, and the electric signal may provide a positive or negative bias.

[0035] Alternatively, or additionally, the power supply (276) may be an alternating current (AC) power source for providing a time-varying conditioned signal to the electrode (223). In this embodiment, the AC power source provides a signal to the electrode. The signal includes a controlled waveform of a specific frequency, duty cycle, offset relative to ground, and peak-to-peak value. All of these parameters can be adjusted to achieve optimal results by considering the desired heating profile and deposition characteristics. In one example, while the substrate is on a chuck having a ceramic heater (288) maintained within the same temperature range, the substrate temperature is controlled to be maintained within the range of 550°C to 650°C. The substrate is chucked onto the surface of the ceramic heater by the electrostatic force generated between the wafer and the electrode (223). In this example, the voltage signal varies over time as a square wave with 20 Hz, a 20% duty cycle, + / - 1000 V, and a 0 V offset. These values ​​are not intended to be absolute. This example includes values ​​around given values ​​within 10%, for instance.

[0036] In one embodiment, the power supply unit (276) is coupled to the electrode (223) through an interface circuit unit (177) comprising a power supply amplifier (279) and a filter (277). Examples of circuits that can be communicably coupled between the power supply unit (276) and the electrode (223) to serve as the filter (277) are discussed below. The power supply unit (276) may be coupled to a power supply amplifier (279) for amplifying an electrical signal from the power supply unit. The amplified electrical signal passes through the filter (277) to remove noise and any RF current from the biasing voltage from the power supply system (280) from the amplified electrical signal. The amplified and filtered electrical signal is provided to the conductive member (286) by the connector (282). The amplified and filtered electrical signal is provided to the electrode (223) and the substrate (121) to enable electrostatic clamping of the substrate (121). The electrode (223) can also function as an RF ground, and RF power is coupled to ground by the connector (281). The capacitor (278) can be coupled to the ground path to prevent the biasing voltage from going to ground. In this way, the electrode (223) functions as a substrate biasing electrode and an RF return electrode.

[0037] In some embodiments, the body (228) may include one or more built-in heaters (288) for providing heat to the body (228). Next, heat from the heater (288) is transferred to the substrate (121) to enhance a manufacturing process, such as a deposition process. The heater (288) may or may not be positioned parallel to the electrode (223). Although the heater (288) is shown in a position below the electrode (223), the electrode may be placed along or above the same plane as the heater (288). The heater (288) may be a single continuous metal line or may be in the form of discontinuous metal lines. The heater (288) may be any heating device suitable for providing inductive or resistive heating to the electrostatic chuck. A temperature sensor (not shown), such as a thermal couple, may be built into the body (228). The temperature sensor may be connected to a temperature controller (not shown) that provides a control signal to a power supply (283) to control the temperature of the body (228).

[0038] The heater (288) is coupled to a heater power supply unit (283) via a support stem (226) to supply power to the heater (288). The power supply unit (283) may include a direct current (DC) power source, an alternating current (AC) power source, or a combination of both. In one embodiment, the power supply unit (283) is an alternating current (AC) power source for providing an AC signal to the heater (288). The heater (288) may be composed of a resistive metal, a resistive metal alloy, or a combination of both. Suitable materials for heating elements may include those having high thermal resistance, such as tungsten (W), molybdenum (Mo), titanium (Ti), etc. The heater (288) may also be manufactured from a material having thermal properties substantially similar to the thermal properties of the material comprising the body (228), e.g., a coefficient of thermal expansion, in order to reduce stress caused by mismatched thermal expansion.

[0039] Generally, the resistivity of AlN materials varies with temperature, which can lead to increased coupling between the embedded chucking electrode (223) and the heaters (288) because they are physically close. Therefore, alternatively, low-frequency signals and harmonic noise, which are coupled to the chucking electrode through the AlN dielectric chucking materials and primarily appear on the AC line side of the heater circuit that affects the chucking voltage, can be filtered by the filter (277). Examples of low-frequency signals include frequencies from 45 Hz to 65 Hz, including standard line frequencies of 50 Hz and 60 Hz. The positioning of the filter (277) shown in FIG. 2 is an example. The filter (277) can be placed at any suitable locations with respect to the electrostatic chuck, whether inside or outside the chamber environment, further away from or closer to the noise sources.

[0040] To reduce leakage current through the heater, an isolation transformer (246) may be placed between the heater (288) and the heater power supply (283). The isolation transformer (246) is used to block the ground current path. In this case, the isolation transformer (246) may include primary coil windings (247) and secondary coil windings (249). The primary coil windings (247) may be connected to the power supply (283), while the secondary coil windings (249) may be connected to the electrical load (i.e., the heater (288)) to be protected. Thus, the heater (288) may be electrically isolated from the AC voltage source and from any transients from an external source to reduce leakage current. In most cases, the isolation transformer (246) should be designed to withstand the maximum ESC voltage without breakdown, without allowing any DC current across its primary and secondary coil windings. However, AC current can freely pass between the primary and secondary coil windings of the isolation transformer (246). Depending on the configuration of the heater (288), the isolation transformer (246) may be a single-zone or multi-zone isolation transformer. In cases where the electrostatic chuck includes multiple heating zones, a single transformer or multiple transformers having multiple primary and / or secondary coil windings may be used to maintain DC isolation between the heaters to ground.

[0041] The filter (277) may include various passive and active circuits to remove AC noise according to the spectrum of frequencies within the noise that need to be removed. The filter (277) may remove incoming noise by operating a ceramic heater while maintaining an electrostatic force on the substrate. In some examples, AC line frequency components based on a power line frequency of 50 Hz or 60 Hz, including harmonics of these frequencies up to several kHz, may be targeted. Such a filter may have various configurations including configurations of low-pass, high-pass, band-pass, band-reject, and notch filters. As an additional example, consider AC noise coupled to a DC or low-frequency square wave chucking signal while performing a 3.4 μm carbon film deposition at 630°C. The chucking signal level may be affected by such AC noise components. When measured, such noise typically appears to be periodic or appears to include specific frequencies or multiple frequency components. For example, noise consisting of 60 Hz switching noise typically includes harmonic frequencies up to several kHz.

[0042] In one embodiment, the filter (277) is a passive circuit having an iron core inductor with an inductance of 25 mH, but various inductances may be used. For 60 Hz switching noise, the 25 mH iron core inductor causes attenuation factors of 50 dB, 13.8 dB, and 1.4 dB at frequencies of 13.56 mH, 1800 Hz, and 180 Hz, respectively, which is about 7% of the ESC current noise level, i.e., 25 ± 2 mA, when tested in a chamber and process as described above.

[0043] FIG. 3 illustrates a schematic diagram of another exemplary passive filter circuit according to some embodiments of the present technology. The circuit (300) is a passive twin-T band rejection filter. The filter comprises resistive and capacitive elements forming a network of two T-circuits having a noise attenuation factor greater than 40 dB at the designed frequency. The attenuation value and frequency response are related to specific values ​​of the resistors and capacitors. In one embodiment, the first T-circuit includes resistors (R1 and R2) and a capacitor (C1), while the second T-circuit includes a resistor (R3) and capacitors (C2 and C3). In this example, the resistance value for each of the resistors (R1 and R2) in the first T-circuit is about twice the resistance value for the resistor (R3) in the second T-circuit. Similarly, the capacitance value for the capacitor (C1) in the first T-circuit is about twice the capacitance value for the capacitors (C2 and C3) in the second T-circuit. In this example, the values ​​are set as close as possible to these relative values, taking into account standard values ​​for widely available components and a 5% tolerance.

[0044] In one example, the filter described above is implemented with resistance values ​​of 10 MΩ and 5 MΩ and capacitance values ​​of 530 pF and 260 pF. These values ​​provide filtering for a noise signal having a fundamental frequency of 60 Hz, 7.8 VDC + 4 Vpp (50%) to provide attenuation to, for example, 2.55 Vdc + 0.06 Vpp (2%). Such a noise signal may occur, for example, during chemical vapor deposition processing at temperatures between 550°C and 650°C. Variations in the ESC power supply current and voltage affect the output terminal V O It is reflected linearly at the filter output level. The output impedance of the circuit (300) is about 100kΩ, which matches the impedance of a typical isolation amplifier circuit that can be used with an ESC.

[0045] FIG. 4 illustrates a schematic diagram of an exemplary active filter circuit according to some embodiments of the present technology. The filter circuit (400) includes an active stage built around an operational amplifier (402) and a passive stage including the aforementioned passive filter circuit. The operational amplifier (402) adjusts the gain applied to the input signals so that the DC or peak output signal level from the filter corresponds to the DC or peak input signal level. This signal level matching ensures that the filter appears transparent or unaffected by the operation of the power supply system, other than providing noise attenuation. In the example illustrated in FIG. 4, the gain is set by using the operational amplifier (402) as a voltage follower having a high input impedance, which is set by a control circuit including resistors (R4 and R5). Alternatively, the gain may be set by connecting a resistor divider network to the operational amplifier.

[0046] In one example, the circuit described above includes resistors and capacitors within the passive stage having previously discussed values. A filter is applied to reduce noise having a fundamental frequency of about 60 Hz and measurable harmonics up to about 3 kHz. R4 has a value of about 5 MΩ. R5 is adjustable and can be set to about 228 kΩ in a typical system as described herein. V CCis 20V. The active filter response exhibits a notch centered at approximately 56Hz. The active filter circuit can be configured to filter the ESC current, ESC voltage, or both. Gain adjustment can be achieved, for example, through firmware for a system controller (such as the system controller (175)) within the power supply system, through variable resistor control accessible to the operator, or by designing the power supply system for a specific known operating environment. The filter is transparent, which means that the steady-state chucking signal is hardly affected, and the rise and fall times of the AC chucking signal remain substantially unchanged. The filter also operates without substantially slowing down the chucking voltage rise time or dechucking voltage fall time that the substrates undergo while they are being processed.

[0047] FIG. 5 illustrates a schematic diagram of another exemplary active filter circuit according to some embodiments of the present technology. The filter circuit (500) again includes an active stage and a passive stage including a passive filter circuit built around an operational amplifier (402). The operational amplifier (402) adjusts the gain applied to the input signals for signal level matching. In the example illustrated in FIG. 5, the gain is set by adjusting the value of R5 in any manner previously discussed. V CCThe operational amplifier (402) is supplied by two 208 VAC to 10 VDC power supplies (502 and 504) to achieve the required current. A single power supply with sufficient current capability may be used instead. These power supplies are connected to a voltage clamping circuit including R7, R8, C4, and diode VR1 to provide overvoltage protection. R7 and R8 are used in parallel to allow for closer tuning of the total resistance value using off-the-shelf resistors. The passive filter portion of the circuit (500) also includes two resistors (R3a and R3b) in parallel to provide the resistance of R3, as shown in the previous drawings. This again allows for higher precision in setting the resistance value using off-the-shelf components. A capacitor (C5) is added to the input of the circuit (500) to act as a low-pass filter.

[0048] FIG. 6 illustrates a flowchart of a method for supplying power to the electrodes of an electrostatic chuck according to some embodiments of the present technology. The method (600) may be performed in one or more chambers including the chamber previously described herein. The method (600) may use the electrostatic chuck previously described herein, together with the illustrated filters and other components. The method (600) may include optional operations or conditions that may or may not be specifically associated with some embodiments of the present technology. For example, many of the operations are described to provide a wider range of structures used, but may be performed by alternative methods that are not critical to the technology or are easily recognizable. As understood from the description of gain settings below, in some embodiments, the semiconductor processing system may be designed so that the gain can be actively monitored and adjusted through an automated feedback process or manually by an operator.

[0049] In operation (602) of method (600), a chucking voltage is applied to the chuck electrode (223). This voltage may be DC or AC, for example, a square wave having a specific duty cycle, offset, etc. In operation (604), the ceramic heater (288) is energized to raise and maintain the temperature of the substrate being processed. In operation (608), the power supply signal is filtered to remove noise while maintaining electrostatic force on the substrate (121). In some embodiments, filtering is partially achieved by applying at least 40 dB of attenuation at a designed frequency of 45 Hz to 65 Hz while the substrate is maintained at a temperature of 550°C to 650°C. The filter may include passive stages, active stages, or both. The filter may also be based on an inductor. In operation (610), a gain is set for the power supply signal to be applied during filtering so that the filter output signal level corresponds to the filter input signal level. Optionally, the signal level may be monitored in operation (612). If the signal level changes, the gain may be reset by repeating operation (610). Otherwise, in operation (614), the substrate (121) is processed within the chamber of the semiconductor processing system.

[0050] FIG. 7 illustrates a chart illustrating the effects of filtering power supplied to an electrostatic chuck according to some embodiments of the present technology. The voltage waveform chart (700) illustrates examples of ESC current and voltage noise attenuation before and after the implementation of the active noise filter discussed above in a semiconductor processing system having a chamber with a ceramic heater temperature ranging from 550°C to 575°C. Waveform (702) represents the unfiltered ESC current, and waveform (704) represents the unfiltered ESC voltage. Waveform (706) represents the filtered ESC current, and waveform (708) represents the unfiltered ESC voltage. The high and low signal voltages are 550V and 350V, respectively. The original noise current fluctuation for the high voltage signal is about 2.5mA at 0V, and the noise current fluctuation for the low voltage signal is less than 3mA at 0V.

[0051] In the preceding description, for the purposes of explanation, many details have been presented to provide an understanding of various embodiments of the present technology. However, it will be apparent to those skilled in the art that certain embodiments may be practiced without some of these details or with additional details.

[0052] Although some embodiments have been disclosed, those skilled in the art will recognize that various modifications, alternative configurations, and equivalents may be used without departing from the spirit of the embodiments. Additionally, to avoid unnecessarily obscuring the art, many well-known processes and elements have not been described. Accordingly, the above description should not be construed as limiting the scope of the art.

[0053] Where a range of values ​​is given, each value existing between the upper and lower limits of such range is interpreted as also specifically stated up to one-tenth of the single-digit value of the smallest digit of the lower limit, unless otherwise clearly indicated in the context. Any sub-range between any mentioned values ​​or unmentioned intermediate values ​​within the mentioned range and any other mentioned or intermediate value within the mentioned range is included. The upper and lower limits of such sub-ranges may independently be included in or excluded from such ranges, and each range is also included in the description insofar as any specifically excluded limit is in the specified range, whether one or both of the upper and lower limits are included in such sub-ranges or both are excluded from such sub-ranges. Where the mentioned range includes any one or both of the limits, ranges excluding any one or both of such included limits are also included.

[0054] As used in the present invention and the appended claims, singular forms (“a,” “an,” and “the”) include plural references unless the context clearly indicates otherwise. Thus, for example, a reference to “heater” includes plural such heaters, and a reference to “filter” includes one or more filters and equivalents thereof known to those skilled in the art.

[0055] Additionally, as used herein and in the following 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 actions, but do not exclude the presence or addition of one or more other features, integers, components, actions, acts, or groups. The words “coupled,” “connected,” “disposed,” and similar terms may refer to a direct connection or placement between components, or a connection or placement with or between interposed components.

Claims

Claim 1 A semiconductor processing system comprising: a processing chamber; an electrostatic chuck partially disposed within the processing chamber—the electrostatic chuck comprises at least one electrode and a heater—; a power supply unit for providing a signal to the at least one electrode to provide an electrostatic force for fixing a substrate to the electrostatic chuck; and a filter communically coupled between the power supply unit and the at least one electrode, wherein the filter is configured to remove noise introduced by operating the heater while the electrostatic force on the substrate is maintained, and the filter comprises: a passive stage; and an active stage communically coupled to the passive stage, wherein the active stage comprises: an operational amplifier; and a control circuit communically coupled to the operational amplifier and for setting the gain of the filter such that the output signal level from the filter corresponds to the input signal level for the filter. Claim 2 A semiconductor processing system according to claim 1, wherein the filter comprises a passive circuit including at least one of a plurality of resistors and capacitors or an inductor. Claim 3 A semiconductor processing system according to claim 1, wherein the filter includes a circuit, and the circuit is configured to provide at least 40 dB of attenuation at a designed frequency of 45 Hz to 65 Hz while the heater maintains the temperature of the substrate at 550 ℃ to 650 ℃. Claim 4 A semiconductor processing system according to claim 3, wherein the filter comprises a twin-T band rejection circuit, and the first T-circuit comprises at least one resistor having a resistance value twice the resistance value of a resistor in the second T-circuit, and a capacitor having a capacitance value twice the capacitance value of at least one capacitor in the second T-circuit. Claim 5 delete Claim 6 delete Claim 7 A semiconductor processing system according to claim 1, wherein the power supply is configured to provide a voltage that varies over time as a square wave with a frequency of 20 Hz, a duty cycle of 20%, a magnitude of + / - 1000 V, and a 0 V offset. Claim 8 A method for processing a substrate in a semiconductor processing system, comprising: applying a chucking voltage to an electrostatic chuck supporting the substrate in a semiconductor processing chamber; energizing a heater to raise the temperature of the substrate; filtering the power supply signal providing the chucking voltage to remove noise introduced into the power supply signal by the heater while the electrostatic force on the substrate is maintained; setting a gain applied to the power supply signal during the filtering so that an output signal level corresponds to an input signal level; and processing the substrate in the semiconductor processing chamber, wherein the power supply signal is filtered using a filter comprising a passive stage, an operational amplifier communically coupled to the passive stage, and a control circuit communically coupled to the operational amplifier, and the control circuit is for setting the gain of the filter so that an output signal level from the filter corresponds to an input signal level for the filter. Claim 9 A method for processing a substrate in a semiconductor processing system, wherein, in claim 8, the power supply signal is filtered using a passive circuit comprising at least one of a plurality of resistors and capacitors or an inductor. Claim 10 A method for processing a substrate in a semiconductor processing system, wherein the step of filtering the power supply signal further comprises the step of applying at least 40 dB of attenuation at a designed frequency of 45 Hz to 65 Hz while the substrate is maintained at a temperature of 550 ℃ to 650 ℃. Claim 11 A method for processing a substrate in a semiconductor processing system, wherein, in claim 10, the power supply signal is filtered using a twin-T band rejection circuit, and the first T-circuit comprises at least one resistor having a resistance value twice the resistance value of a resistor in the second T-circuit and a capacitor having a capacitance value twice the capacitance value of at least one capacitor in the second T-circuit. Claim 12 delete Claim 13 A method for processing a substrate in a semiconductor processing system, wherein, in claim 8, the chucking voltage varies over time as a square wave with a frequency of 20 Hz, a duty cycle of 20%, a magnitude of + / - 1000 V, and a 0 V offset. Claim 14 A power supply system for electrostatic chucking in a semiconductor processing chamber, comprising: a power supply unit configured to provide a signal to an electrode within the electrostatic chuck; and a filter communically coupled to the power supply unit, wherein the filter is configured to remove noise introduced by operating a heater within the electrostatic chuck while an electrostatic force is maintained on a substrate, and wherein the filter comprises an active stage and a passive stage, wherein the active stage comprises: an operational amplifier; and a control circuit communically coupled to the operational amplifier and configured to set the gain of the filter such that the output signal level from the filter corresponds to the input signal level for the filter. Claim 15 A power supply system for electrostatic chucking in a semiconductor processing chamber, wherein the filter comprises a passive circuit including at least one of a plurality of resistors and capacitors or an inductor. Claim 16 A power supply system for electrostatic chucking in a semiconductor processing chamber, wherein the filter comprises a circuit, the circuit being configured to provide at least 40 dB of attenuation at a designed frequency of 45 Hz to 65 Hz while the heater maintains the temperature of the substrate at 550 ℃ to 650 ℃. Claim 17 A power supply system for electrostatic chucking in a semiconductor processing chamber, wherein the filter comprises a twin-T band rejection circuit, and the first T-circuit comprises at least one resistor having a resistance value twice the resistance value of a resistor in the second T-circuit and a capacitor having a capacitance value twice the capacitance value of at least one capacitor in the second T-circuit. Claim 18 A power supply system for electrostatic chucking in a semiconductor processing chamber, wherein, in claim 14, a power supply amplifier communicationably coupled between the power supply unit and the filter. Claim 19 delete Claim 20 A power supply system for electrostatic chucking in a semiconductor processing chamber, wherein the power supply unit is configured to provide a voltage that varies over time as a square wave with a frequency of 20 Hz, a duty cycle of 20%, a magnitude of + / - 1000 V, and a 0 V offset.

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