High-side current monitor

Abstract

Disclosed are systems, methods, and apparatus for current monitoring. A current monitor includes a high-voltage side configured to obtain a signal indicating current flowing through a conductor and apply different levels of gain to different frequency bands of the signal to generate conditioned signals. A low-voltage side of the current monitor is electrically isolated from the high-voltage side and configured to split the conditioned signal to generate a plurality of output signals, each indicating the level of current flowing in one of the different frequency bands. An isolation amplifier is configured to transmit the conditioned signal from the high-voltage side to the low-voltage side while electrically isolating the high-voltage side from the low-voltage side.

Description

[0001] Priority is required under 35 USC § 119.

[0002] This patent application claims priority to Provisional Application No. 62 / 862,459, entitled “High-Side Current Monitor,” filed on June 17, 2019, which has been assigned to its assignee and is hereby expressly incorporated herein by reference. Technical Field

[0003] The present invention relates generally to power monitoring, and more specifically, to a method and apparatus for monitoring the current supplied to a load. Background Technology

[0004] Monitoring current is important in many situations. For example, electrostatic chucks are used to support workpieces (e.g., wafers) in various processing systems. In deposition systems, for instance, electrostatic chucks can be used to hold a wafer in place while a thin film is deposited onto it. In etching systems, as another example, electrostatic chucks can be used to hold a wafer in place while chemically etching material from it.

[0005] An electrostatic chuck uses electrostatic force to hold a workpiece in place. The electrostatic chuck has electrodes energized by a clamping voltage, which electrostatically clamp the workpiece to the chuck's surface. The electrodes in the electrostatic chuck are coupled to an electrostatic power supply and a controller. The electrostatic power supply receives control signals from the controller and generates a clamping voltage suitable for clamping the substrate with clamping force.

[0006] Proper workpiece positioning relative to the electrostatic chuck is important at various times before, during, and after typical workpiece machining. For example, it is important to ensure the workpiece is correctly loaded onto the electrostatic chuck before applying the clamping voltage. As another example, it may be necessary to determine whether the workpiece is clamped or not at a particular time.

[0007] The electrostatic power supply unit may include: a direct current (DC) voltage generator configured to generate a DC clamping voltage for the clamping electrode assembly of the electrostatic chuck; and an alternating current (AC) voltage generator configured to generate an AC signal. The position of the workpiece can be detected by monitoring the capacitance of the combination of the workpiece and the electrostatic chuck. For example, when the workpiece is correctly positioned on the electrostatic chuck, the sensed capacitance may be higher than when the workpiece is not correctly positioned.

[0008] The varying levels of current supplied to the electrostatic chuck (in response to the application of AC voltage) make it possible to monitor the capacitance of the electrostatic chuck, and therefore, the position of the workpiece can be monitored by monitoring the current supplied to the electrostatic chuck.

[0009] Because the output side needs to operate in the thousands of volts range, existing techniques for monitoring current typically utilize shunt resistors on the return side of the electrostatic chuck power supply (between the electrostatic chuck and ground). Low-side sensing avoids the problem of isolating high voltage from the measurement output, but usually at the cost of noise. High-side current sensing avoids the noise problem, but requires isolation. An isolation amplifier can be used to separate the high-voltage output of the electrostatic chuck power supply from the measurement signal, but unfortunately, isolation amplifiers typically have significant electrical noise, which limits the lowest possible resolution of the system.

[0010] As processing technology continues to move towards higher-power amplifiers with higher output currents, scaling current measurement systems is required to accommodate larger signals by reducing gain. When current monitors are also used for capacitance sensing, reducing gain drives relatively small capacitance signals below the noise floor. This results in an unacceptable reduction in the resolution of capacitance measurement capabilities. Consequently, existing approaches to monitoring current are undesirable and almost certainly unacceptable in the future. Summary of the Invention

[0011] One aspect can be characterized as a current monitor, comprising a high-voltage side configured to acquire a signal indicating the current flowing through a conductor and to apply different levels of gain to different frequency bands of the signal to generate an adjusted signal. A low-voltage side is electrically isolated from the high-voltage side and configured to split the adjusted signal to generate multiple output signals, each of which indicates a current level at one of the different frequency bands. An isolation amplifier is configured to transmit the adjusted signal from the high-voltage side to the low-voltage side while electrically isolating the high-voltage side from the low-voltage side.

[0012] Another method for monitoring current includes: acquiring a signal indicating current flowing through a conductor; splitting the signal into at least two frequency bands to obtain at least two high-voltage side signals; and applying a gain to each of the at least two high-voltage side signals. The at least two high-voltage side signals are combined to generate an adjusted signal transmitted to a low-voltage side via a current isolation path. The adjusted signal is split into at least two frequency bands on the low-voltage side to obtain at least two output signals, and one or more of the at least two output signals are used to monitor the current in the conductor.

[0013] Another aspect is a system for current monitoring, comprising: a power supply configured to apply a voltage to an electrostatic chuck, the voltage including a direct current (DC) component and an alternating current (AC) component. The system also includes a current monitor with means for obtaining a signal indicating the current flowing through a conductor that couples the power supply to the electrostatic chuck. The system further includes means for splitting the signal into at least two frequency bands to obtain at least two high-voltage side signals, means for applying gain to each of the at least two high-voltage side signals respectively, and means for combining the at least two high-voltage side signals to generate an adjusted signal. Furthermore, the system includes means for transmitting the adjusted signal to a low-voltage side via a current isolation path, and the low-voltage side includes means for splitting the adjusted signal on the low-voltage side into at least two frequency bands to obtain at least two output signals. The system also includes means for monitoring the current in the conductor using one or more of the at least two output signals. Attached Figure Description

[0014] Figure 1 A block diagram is shown depicting an exemplary environment in which a high-side current monitor can be utilized;

[0015] Figure 2 It is a description Figure 1 A block diagram illustrating an exemplary embodiment of the high-side current monitor;

[0016] Figure 3 It is a flowchart depicting a method for traversing in conjunction with the embodiments disclosed herein; and

[0017] Figure 4 This is a block diagram depicting processing components that can be used in conjunction with the embodiments disclosed herein. Detailed Implementation

[0018] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or superior to other embodiments.

[0019] First refer to Figure 1 , Figure 1 An exemplary electrostatic holding system 100 is illustrated, which is one environment in which an embodiment of the high-side current monitor disclosed herein can be utilized. As depicted, the electrostatic holding system 100 includes an electrostatic chuck power supply unit 102, a high-side current monitor 103, and an electrostatic chuck 104. As shown, the electrostatic chuck 104 is located within a plasma processing chamber 106, and a workpiece 110 is shown being held to the electrostatic chuck 104. A workpiece position module 107 is also shown, configured to provide an indication of the position of the workpiece 110 based on the current measured by the high-side current monitor 103.

[0020] In this exemplary application, the plasma processing chamber 106 can be implemented by a substantially conventionally constructed chamber (e.g., including a vacuum enclosure evacuated by one or more pumps (not shown)). Furthermore, as those skilled in the art will understand, plasma excitation in the plasma processing chamber 106 can be achieved by any of a variety of sources, including, for example, a helical plasma source comprising a magnetic coil and an antenna to ignite and sustain plasma 114 in the reactor, and may provide a gas inlet to introduce gas into the plasma processing chamber 106.

[0021] As depicted, the workpiece 110 to be processed (e.g., a semiconductor wafer) is at least partially supported by an electrostatic chuck 104, and power is applied to the electrostatic chuck 104 via one or more conductors (e.g., cables). For simplicity, only a single conductor 116 coupling the electrostatic chuck 104 is shown, but it should be recognized that the aspects described herein apply to both unipolar and multipolar chucks. As an example, those skilled in the art will understand that a six-polar electrostatic chuck can be combined with six power lines and six corresponding high-side current monitors.

[0022] The electrostatic chuck power supply unit 102 can be implemented by any of a variety of known or under-development power supply units capable of applying voltages including DC and AC components. For example, the electrostatic chuck power supply unit 102 may be able to apply 1000 volts DC and 10 to 20 volts AC (peak to peak) at 1 kHz, but these voltages and frequencies are merely exemplary and can vary depending on many factors. As described above, the DC voltage generates a DC clamping voltage at the electrostatic chuck 104, which pulls the workpiece 110 onto the electrostatic chuck, while the AC voltage can be used to detect the position of the workpiece 110 relative to the electrostatic chuck 104.

[0023] Next reference Figure 2 This shows what can be used to implement Figure 1An exemplary high-side current monitor 203 is shown as high-side current monitor 103. As shown, a shunt impedance Z is provided along a conductive path including conductor 216, which couples a power source, such as the electrostatic chuck power supply 102, to node v1 on one side of the shunt impedance Z. This conductive path also includes the shunt impedance Z, and another portion of conductor 216, which couples the other side of the shunt impedance Z at node v2 to the electrostatic chuck 104. Therefore, the shunt impedance Z is provided in the current path from the power source (e.g., the electrostatic chuck power supply 102) to the load (e.g., the electrostatic chuck 104). As a result, the voltage across the shunt impedance Z (between nodes v1 and v2) varies with the current supplied to the electrostatic chuck 104; therefore, the voltage between nodes v1 and v2 can be used as a signal indicating the current supplied to the electrical load (e.g., the electrostatic chuck 104). As shown, a first lead 220 is coupled to node v1 and a second lead 221 is coupled to node v2. Therefore, in Figure 2 In this embodiment, the signal (indicating current) is obtained by coupling leads 220, 221 across the shunt impedance Z in the current path of conductor 216. As discussed above, the voltage applied to v1 can be approximately 1000VDC, and the voltage at v2 is a floating ground, which is a local reference that varies with the output voltage of the power supply (such as the electrostatic chuck power supply unit 102). For example, the floating ground at v2 may differ from the voltage applied at node v1 by approximately 1 volt.

[0024] Generally, the shunt impedance Z is a complex quantity that includes resistive and reactive components; however, in many implementations, the shunt impedance Z can be implemented as a resistor with essentially zero reactance. As an example, but not limited to, the shunt impedance Z can be implemented by a 100-ohm resistor, and the full-scale current through the shunt impedance Z can be 10 mA. Therefore, the voltage across the shunt impedance Z can be approximately 1 volt or less. Because the voltage difference between v1 and v2 is caused by current, a positive voltage at v1 relative to v2 indicates that current is entering the electrostatic chuck 104.

[0025] It should be recognized that the shunt impedance Z is only one way to sense and obtain a signal indicating the current passing through conductor 216, and there are several other ways to sense current, such as Hall effect sensors, fluxgate sensors and transformers.

[0026] As shown, node vl is coupled to high-side band splitter 218 via lead 220, and high-side band splitter 218 is coupled to gain component 222, which is coupled to adder 224. The output of adder 224 is coupled to the high-side of isolation amplifier 226, and the low-side of isolation amplifier 226 is coupled to low-side band splitter 228, which provides multiple output signals, including a first output signal 230 and a second output signal 232. It should be understood that the depicted components are intended to convey logical functions, and these functions can be implemented by common underlying physical components or through the distribution of physical components. For example, filters and gain amplifiers can be implemented by a common operational amplifier (op-amp) or by separate physical components. It should also be understood that the depicted functions can be implemented by hardware or a combination of hardware and software.

[0027] Typically, the isolation amplifier 226 isolates the high-voltage side of the current monitor 203 from the low-voltage side current of the current monitor 203, while allowing signal information to pass through the barrier without any ohmic path between the input and output.

[0028] Isolation can be achieved using a fully analog isolation amplifier. Alternatively, a non-isolated amplifier subcircuit can be used, consisting of an analog-to-digital converter followed by an isolator (which can utilize optical, capacitive, or magnetic principles). An isolation power supply unit, independent of the electrostatic chuck power supply unit 102, can be used to power the components of the isolation amplifier. As a specific example, the isolation amplifier 226 can be implemented using an isolation amplifier with part number ISO224ADWVR sold by Texas Instruments, Inc., which can be powered by an isolation power supply unit with part number NMS0515C sold by Murata Manufacturing Co., Ltd. However, it should be recognized that other components from other sources can be used to implement the isolation amplifier 226 and to power the isolation amplifier 226.

[0029] refer to Figure 2 At the same time, refer to Figure 3 , Figure 3 It is a description that can be combined Figure 2The flowchart illustrates an exemplary method of traversing embodiments depicted herein. In operation, when a power source such as the electrostatic chuck power supply unit 102 supplies power to a load such as the electrostatic chuck 104 (block 302), the current through the shunt impedance Z will generate a voltage signal at node v1, indicating the current level flowing through the shunt impedance Z (block 304). The voltage signal (also more simply referred to herein as the signal) is provided to the high-side band splitter 218 and is then split by the high-side band splitter 218 into at least two bands to obtain at least two high-side signals (block 306). As depicted, the high-side band splitter 218 may include two or more filters, and the gain component 222 may include the same number of gain amplifiers to generate two or more signals, which are added by adder 224 to generate an adjusted voltage signal, which is applied to the high-side of isolation amplifier 226.

[0030] exist Figure 2 In the illustrated embodiment, the high-voltage side band splitter 218 includes two filters: a high-pass filter 234 for passing frequencies of the signal higher than a first frequency (to obtain a first signal 238 in the first frequency band); and a low-pass filter 236 for passing frequencies of the signal lower than a second frequency to obtain a second signal 240 in the second frequency band. Furthermore, Figure 2 The current monitor 203 depicted includes a first gain amplifier 242 that applies a first gain level to a first signal 238 and a second gain amplifier 244 that applies a second gain level to a second signal 240. As shown, adder 224 is positioned and configured to combine the first gain-adjusted signal and the second gain-adjusted signal to produce an adjusted signal applied to isolation amplifier 226.

[0031] In some implementations, low-pass filter 236 can pass DC information below 10Hz and high-pass filter 234 can pass AC information above 100Hz. In many implementations, filtering is performed in the analog domain using any of a variety of analog filtering techniques such as Sallen-Key filtering, but other types of active and / or passive filtering can be used. In some implementations, high-pass filter 234 and associated first gain amplifier 242 (an amplifier with gain = x) can be implemented as a single operational amplifier circuit and low-pass filter 236 and associated second gain amplifier 244 (an amplifier with gain = y) can be implemented as another operational amplifier circuit. It is also contemplated that the voltage signal at v1 can be converted to a digital signal and then filtered, digitally amplified, and summed in the digital domain. In other words, high-pass filter 234, low-pass filter 236, first gain amplifier 242, second gain amplifier 244, and adder 224 can be implemented using digital components.

[0032] Reference again Figure 3 The gain is applied separately to at least two high-voltage side signals (box 308). Figure 2 In the embodiment depicted, a first gain amplifier 242 with a gain equal to x is coupled to a high-pass filter 234, and a second gain amplifier 244 with a gain equal to y is coupled to a low-pass filter 236 (where x may be equal to or not equal to y); thus, DC information (e.g., below 10 Hz) and AC information (e.g., above 100 Hz) can be amplified with different gain values ​​respectively.

[0033] In the context of the electrostatic chuck system 100, the separate amplification advantageously allows higher frequency band information (also known as AC current information) to be amplified to a higher level for more accurate detection of changes in AC current (which indicates capacitance changes in the workpiece 110 and the electrostatic chuck 104). Furthermore, it is advantageous to perform amplification of the components of the voltage signal before the isolation amplifier 226, thus eliminating the need for gain in subsequent stages and preventing any noise generated by the isolation amplifier 226 from being further amplified.

[0034] As shown, at least two high-voltage side signals are combined by adder 224 to generate an adjusted signal (box 310). In the analog domain, as those skilled in the art will understand, adder 224 can also be implemented as an operational amplifier. The adjusted signal is then transmitted from the high-voltage side to the low-voltage side using isolation amplifier 226, while electrically isolating the high-voltage side from the low-voltage side (box 312). Isolation amplifier 226 operates to separate the low-voltage side from the high-voltage side by generating current isolation as known in the art. Advantageously, isolation amplifier 226 separates the high-voltage side (operating with floating ground) of current monitor 203 from the low-voltage side (operating with earth ground as a reference) of current monitor 203; thereby protecting the low-voltage side from damage.

[0035] As shown, the adjusted voltage signal on the low-voltage side (also known as the low-voltage side combined signal) is split by the low-voltage side band splitter 228 to obtain at least two low-voltage side output signals (block 314). The low-voltage side band splitter 228 can reflect the high-voltage side band splitter 218 in terms of the number of frequency bands used. Figure 2 As shown, the low-voltage side band splitter 228 includes a high-pass filter 246 and a low-pass filter 248. The high-pass filter 246 and low-pass filter 248 can each have the same frequency response as the high-pass filter 234 and low-pass filter 236 of the high-voltage side band splitter 218. Furthermore, the low-voltage side high-pass filter 246 and low-pass filter 248 can or may not use the same techniques as the high-voltage side high-pass filter 234 and low-pass filter 236. (Refer to again...) Figure 3One or more of the at least two low-voltage side output signals can be used to monitor the current through conductor 216 (box 316). And in the context of the electrostatic chuck system 100, the monitored higher-frequency current (as indicated by the first output signal 230) can be used by the workpiece position module 107 to assess the position of workpiece 110, and the monitored lower-frequency current (as indicated by the second output signal) can be used to assess leakage current in the electrostatic chuck 104.

[0036] As an example of the overall method of the electrostatic holding system 100, assume that the DC current through the shunt impedance Z is 10 mA and the impedance of the shunt impedance Z is 100 ohms (without any reactance component), so as to generate a 1 volt voltage across the shunt impedance Z. Further assume that the gain of y is set to equal 1.0 and the gain of x is set to equal 50.0. The low-pass filter 236 will generate a 1VDC voltage signal and the corresponding second-gain amplifier 244 will apply unity gain to generate 1VDC. Conversely, the isolation amplifier 226 will display 1VDC as an output and the low-pass filter 248 on the low-voltage side will generate 1VDC relative to the ground.

[0037] Regarding the AC component (used to calculate capacitance), assume a 1kHz signal is inserted (e.g., via electrostatic chuck power supply 102) to generate a 1kHz AC current across the shunt impedance Z. When a 1mA peak-to-peak current is generated, the high-pass filter 234 will "see" 100mV AC above 1VDC and pass it through, which is amplified 50 times by the second gain amplifier 244 to generate a 5V peak-to-peak signal. Given that the output of the isolation amplifier 226 is + / - 10V, the AC signal can be amplified to occupy a larger range of the isolation amplifier 226. At the low-voltage side output, there may be two signals: a 1V DC signal and a 5V AC peak-to-peak signal. Advantageously, the gains of the high-pass and low-pass processing chains can be set such that when the maximum capacitive load is observed with the maximum DC current, the rails of the isolation amplifier 226 do not exceed the specifications of the isolation amplifier 226 (therefore no clipping occurs). This capability contrasts with prior art approaches that simply allow setting volts per ampere. Furthermore, existing technology systems employ gain amplification after the isolation amplifier, which amplifies the inherent noise of the isolation amplifier.

[0038] To detect the position of workpiece 110 within the context of the electrostatic chuck system 100, a relationship between capacitance and workpiece position can be empirically determined, and a threshold capacitance can be established to indicate, for example, whether workpiece 110 is in place or in the fixture. The threshold capacitance value can be stored in non-volatile memory along with workpiece position data to achieve a mapping between capacitance values ​​and workpiece position. The workpiece position module 107 can use empirically obtained data combined with current measurements (e.g., higher-frequency measurements obtained from the first output signal 230) to obtain the capacitance observed at the electrostatic chuck 104. As readily understood by those skilled in the art, the capacitance of the load can be determined based on AC voltage and current varying over time as follows:

[0039]

[0040] Once the capacitance of the load (e.g., the combination of the electrostatic chuck 104 and the workpiece 110) is obtained, the position of the workpiece 110 can be obtained from the non-volatile memory.

[0041] The second output signal 232 advantageously provides an indication of the low-frequency current passing through conductor 216, which typically indicates the level of low-frequency (e.g., below 10 Hz) leakage current in the electrostatic chuck 104. In many cases, the low-frequency current (indicating leakage current) can be below 1 Hz.

[0042] As described above, the functions and methods described in conjunction with the embodiments disclosed herein can be implemented using hardware, processor-executable instructions encoded in a non-transitory machine-readable medium, or a combination of both. See, for example... Figure 4 A block diagram depicting physical components that can be used to implement the high-side current monitor 103 and its various embodiments (such as current monitor 203) is shown. Furthermore, Figure 4 Multiple instances of the computing device depicted herein can be implemented in the system described herein. As shown, in this embodiment, a display 1112 and non-volatile memory 1120 are coupled to a bus 1122, which is also coupled to random access memory (“RAM”) 1124, a processing section (including N processing components) 1126, a field-programmable gate array (FPGA) or microcontroller 1127, and a transceiver assembly 1128 including N transceivers. Although Figure 4 The components depicted in the text represent physical components, but Figure 4 It is not a detailed hardware diagram; therefore, Figure 4 Many of the components described can be implemented through a common construction or distributed across additional physical components. Furthermore, it is anticipated that other existing and yet-to-be-developed physical components and architectures can be utilized to implement the reference design. Figure 4 The described functional components.

[0043] Display 1112 is typically used to provide a user interface, and in some embodiments, display 1112 is implemented as a touchscreen display. For example, display 1112 may be implemented as part of a high-side current monitor 103 to allow the user to control the gain settings of the first gain amplifier 242 and the second gain amplifier 244 and / or the time constants of the high-pass filter 234 and the low-pass filter 236. Display 1112 may also be used as part of a workpiece position monitor to display information about the position of workpiece 110.

[0044] Generally, non-volatile memory 1120 is a non-transitory memory used to store (e.g., persistently store) data and machine-readable (e.g., processor-executable) code, including executable code associated with implementing the methods described herein. In some embodiments, for example, non-volatile memory 1120 includes bootloader code, operating system code, file system code, and non-transitory processor-executable code to facilitate the foregoing reference. Figure 3 The described method is executed. The non-volatile memory 1120 can also be used to store empirically obtained data that associates workpiece position with capacitance data.

[0045] In many implementations, the non-volatile memory 1120 is implemented using flash memory (e.g., NAND or ONENAND memory), but other memory types are also expected to be utilized. Although it is possible to execute code from the non-volatile memory 1120, the executable code in the non-volatile memory is typically loaded into RAM 1124 and executed by one or more of the N processing components in the processing section 1126.

[0046] In operation, the N processing components of RAM 1124 can typically be operated to execute instructions stored in non-volatile memory 1120 to implement the functionality of one or more components of embodiments of the high-side current monitor 103 and / or workpiece position module 107. Those skilled in the art will understand that processing section 1126 may include a video processor, a digital signal processor (DSP), a graphics processing unit (GPU), and other processing components. In a digital implementation, a DSP may be used to implement... Figure 2 The high-pass filter 234, low-pass filter 236, first gain amplifier 242, and second gain amplifier 244 are depicted in the figure.

[0047] Furthermore, or alternatively, the field-programmable gate array (FPGA) 1127 can be configured to implement one or more aspects of the functions and methods described herein. For example, non-transitory FPGA configuration instructions can be persistently stored in non-volatile memory 1120 and accessed by the FPGA 1127 (e.g., during startup) to configure the FPGA 1127 to implement the functions of the current monitor 103.

[0048] If the computing device 1100 is implemented as a workpiece position module 107 (as a component separate from the high-side current monitor 103), the input components can be operated to receive signals indicating the monitored current (e.g., from the high-side current monitor 103). The output components are typically operated to provide one or more analog or digital signals to implement operational aspects of the components described herein. For example, if the computing device 1100 is implemented as part of the high-side current monitor 103, the output portion can transmit output signals (single or multiple) indicating the current level (e.g., a first output signal 230 and a second output signal 232) to the workpiece position module 107.

[0049] The described transceiver assembly 1128 includes N transceiver chains that can be used to communicate with external devices via wireless or wired networks. Each of the N transceiver chains may represent a transceiver associated with a specific communication scheme (e.g., WiFi, Ethernet, Profibus, etc.).

[0050] The prior description of the disclosed embodiments is provided to enable those skilled in the art to make or use the invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not intended to be limited to the embodiments shown herein, but is accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A current monitor, comprising: On the high-voltage side, it is configured to obtain a signal indicating the current passing through the conductor and apply different levels of gain to different frequency bands of the signal to generate an adjusted signal; On the low-voltage side, electrically isolated from the high-voltage side and configured to split the adjusted signal to generate a plurality of output signals, each of the plurality of output signals indicating the current level at one of the different frequency bands; as well as An isolation amplifier is configured to transmit the adjusted signal from the high-voltage side to the low-voltage side while electrically isolating the high-voltage side from the low-voltage side. The high-voltage side includes: A high-pass filter allows frequencies of the signal higher than a first frequency to pass through, thereby obtaining a first signal in a first frequency band; and A low-pass filter allows frequencies of the signal below the second frequency to pass through, thereby obtaining a second signal in the second frequency band.

2. The current monitor as described in claim 1, wherein, The high-voltage side is configured to obtain the signal by coupling leads across the shunt impedance located in the current path of the conductor.

3. The current monitor as described in claim 1, wherein, The high-voltage side is configured to obtain the signal from a Hall sensor located in the current path of the conductor.

4. The current monitor as described in claim 1, wherein, The high-pass filter is configured to allow frequencies above 50 Hz to pass through, and the low-pass filter is configured to allow frequencies below 20 Hz to pass through.

5. The current monitor as described in claim 1, wherein, The high-pass filter is configured to allow frequencies above 100 Hz to pass through, and the low-pass filter is configured to allow frequencies below 10 Hz to pass through.

6. The current monitor as claimed in claim 1, wherein, The high-voltage side includes: A first gain amplifier applies a first gain level to the first signal; A second gain amplifier applies a second gain level to the second signal; and An adder combines the first signal and the second signal to generate the adjusted signal.

7. The current monitor as claimed in claim 6, wherein, The low-pressure side includes: A high-pass filter allows frequencies of the adjusted signal higher than the first frequency to pass through, thereby obtaining a first output signal among the plurality of output signals; and A low-pass filter allows frequencies of the adjusted signal below the second frequency to pass through, thereby obtaining a second output signal among the plurality of output signals.

8. The current monitor of claim 1, further comprising a workpiece position module configured to receive at least one of the plurality of output signals and provide an indication of the position of a workpiece held in place via current in the first frequency band.

9. The current monitor as claimed in claim 1, wherein, The isolation amplifier includes one or more of optical coupling, capacitive coupling, and magnetic coupling to transmit the adjusted signal from the high-voltage side to the low-voltage side.

10. A method for monitoring current, comprising: Obtain a signal indicating the current flowing through the conductor; The signal is split into at least two frequency bands to obtain at least two high-voltage side signals; A gain is applied to each of the at least two high-voltage side signals; The at least two high-voltage side signals are combined to generate an adjustment signal; The adjusted signal is transmitted to the low-voltage side via a current isolation path; The adjusted signal on the low-voltage side is split into a high-frequency band and a low-frequency band to obtain at least two output signals; Monitor the high-frequency band to evaluate the capacitance of the electrostatic chuck; as well as The current in the conductor is monitored using one or more of the at least two output signals.

11. The method of claim 10, wherein, The signal for transmitting the adjustment includes transmitting the signal for transmitting the adjustment via one or more of optical coupling, capacitive coupling, and magnetic coupling.

12. The method of claim 10, comprising: The capacitance is evaluated to determine the position of the workpiece.

13. A system for current monitoring, comprising: The power supply unit is configured to apply a voltage to the electrostatic chuck, the voltage including a direct current (DC) component and an alternating current (AC) component; as well as Current monitor, including: A means for obtaining a signal indicating the current passing through a conductor, the conductor coupling the power supply unit to the electrostatic chuck; A means for splitting the signal into at least two frequency bands to obtain at least two high-voltage side signals; A means for applying a gain to each of the at least two high-voltage side signals; A means for combining the at least two high-voltage side signals to generate an adjusted signal; A means for transmitting the adjusted signal to the low-voltage side via a current-isolated path; A means for splitting the adjusted signal on the low-voltage side into at least two frequency bands to obtain at least two output signals; and A means for monitoring the current in the conductor using one or more of the at least two output signals.

14. The system of claim 13, wherein, The means for transmitting the adjusted signal includes means for transmitting the adjusted signal via one or more of optical coupling, capacitive coupling, and magnetic coupling.

15. The system of claim 13, comprising: A means for splitting the adjusted signal on the low-voltage side into high-frequency bands and low-frequency bands; as well as A device for monitoring the high-frequency band to evaluate the capacitance of the electrostatic chuck.

16. The system of claim 14, comprising: A device used to evaluate capacitance to determine the position of a workpiece.

17. The system of claim 13, wherein, The device for obtaining a signal indicating the current includes at least one of a shunt resistor or a Hall sensor.

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