Measurement of load capacitance or impedance in high-voltage DC power supplies

Abstract

To provide a power supply capable of monitoring the impedance or capacitance of a load connected thereto.SOLUTION: A power supply comprises a current sensor that measures an oscillating current through a load connected to the power supply, a voltage sensor that measures an oscillating voltage across the load, and a source conductor that outputs the sinusoidal voltage generated by a sinewave oscillator. A micro-controller is coupled to the current sensor, the voltage sensor, and the source conductor. The micro-controller computes the impedance or capacitance of the load by using digital data derived from the three sensors.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates generally to a power supply adapted to generate a direct current (DC) high voltage and capable of monitoring the impedance or capacitance of a connected load, and more particularly to a power supply suitable for use with an electrostatic chuck. [Background technology]

[0002] In the manufacturing process of semiconductors and liquid crystal panels, vacuum chucks and mechanical chuck systems have traditionally been used to secure and handle substrates. However, due to the effects of suction, distortion, and the need for improved reliability, electrostatic chucks are now widely adopted in semiconductor manufacturing equipment to overcome these limitations.

[0003] An electrostatic chuck ("e-chuck") consists of a platen with a surface electrode biased at a high voltage to generate an electrostatic force between the platen and the wafer. Two types of electrostatic chucks are available: Coulomb and Johnsen-Rahbek ("JR") types. They are distinguished by their dielectric properties and, therefore, the way they generate a clamping force. Coulomb chucks function similarly to traditional dielectric capacitors. JR types have a high, but finite, resistance, so that when the surfaces are brought into close contact and a voltage is applied, current flows through the JR and the substrate. A charge accumulates at the interface between the substrate and the dielectric, which generates the clamping force.

[0004] Additionally, different configurations of electrodes (or poles) on the chuck are utilized to obtain different characteristics: monopolar, bipolar (two poles), and multipolar chucks (including six-phase hexapolar types) are available, depending on the application.

[0005] Known power supplies are provided for a full range of e-chucks. The known power supplies have the following characteristics: High voltage bipolar output (positive / negative), Output polarity reversal function for easy wafer chucking / unchucking Ability to sense wafer state by capacitance measurement (Coulomb chuck) or current measurement (JR chuck), and / or Analog and digital interfaces for easy integration into various systems.

[0006] For example, a known power supply suitable for use with a Coulomb chuck is shown in Figure 1. In this example, the power supply is bipolar and has two terminals 26a-26b. A load 10 (e.g., a Coulomb-type electrostatic chuck) is shown connected between the two terminals 26a, 26b. In use, each of the generators 12a-12b generates high direct current (DC) power that is applied to the load 10.

[0007] The power supply shown in FIG. 1 includes a sine wave oscillator 16. In use, the sine wave oscillator 16 generates a sine wave voltage at a predetermined frequency. The sine wave oscillator 16 is connected to a first lead of a capacitor 18, the second lead of which is connected to terminal 26a. The sine wave voltage applied to the first lead of the capacitor 18 causes an oscillating current to flow from ground. A first portion of the oscillating current may flow back to ground through the blocking inductor 14a and the generator 12a. A second portion of the oscillating current may flow back to ground through the load 10, the capacitor 22, and the current-to-voltage converter 20. A third portion of the oscillating current may flow back to ground through the load 10, the blocking inductor 14b, and the generator 12b.

[0008] The first portion of the oscillating current is ideally negligibly small compared to the second portion of the oscillating current, which in turn is nearly equal to the alternating current (AC) flowing through the load 10. Like the first portion, the third portion of the oscillating current is ideally negligibly small compared to the second portion of the oscillating current.

[0009] The parallel arrangement of load 10, blocking inductor 14a, and coupling capacitor 18 creates an oscillating potential in one of the leads of load 10. Similarly, the parallel arrangement of load 10, blocking inductor 14b, and coupling capacitor 22 creates an oscillating potential in the other lead of load 10.

[0010] 1 includes a first sensor that measures the magnitude of the second portion of the oscillating current, which, as described above, is approximately equal to the AC flowing through the load 10. The first sensor includes a current-to-voltage converter 20, a full wave rectifier, a low-pass filter, and an analog-to-digital converter ADC 24a. The first sensor cannot measure phase.

[0011] 1 includes a second sensor that measures the magnitude of the sinusoidal voltage generated by the sinusoidal oscillator 16. The second sensor includes a full-wave rectifier, a low-pass filter, and a channel of the ADC 24a. The second sensor cannot measure phase.

[0012] The power supply shown in FIG. 1 does not directly measure the voltage at terminal 26; the oscillating voltage caused by the flow of the first and second portions of the oscillating current through capacitor 18 is only estimated.

[0013] 1 includes a microcontroller 24 programmed to estimate the capacitance of the load 10 from the digitized magnitude of the sinusoidal voltage, the magnitude of the AC current flowing through the load 10 (approximated from the magnitude of the second portion of the oscillating current), and the values ​​of the capacitors 18, 22. However, in some cases, the estimation of the capacitance of the load 10 may lack accuracy and / or precision.

[0014] The power supply shown in Figure 2 is bipolar. This is shown at terminal A. + and terminal B -Each of them is connected to a load 10. This includes generators 12a to 12b and a monitoring unit 34 (monitor).

[0015] In this example, the monitoring unit 34 includes a sine wave oscillator 16a and a transformer 16b for differentially injecting a sine wave signal through capacitors 18a-18b. Note that the circuit including the sine wave oscillator 16a and the transformer 16b can be considered to form a sine wave oscillator by itself. That is, it generates two voltage signals at the leads of the two secondary coils of the transformer 16b, and a third voltage signal R (e.g., a reference signal) between two resistors connected in series with the two secondary coils. Blocking inductors 14a-14b are used to increase the impedance of the generators 12a-12b at the frequency of the sine wave oscillator 16a.

[0016] As a result of the combined action of the sine wave oscillators 16a and 16b, including the capacitors 18a-18b and the blocking inductors 14a-14b, a small first portion of AC current (i.e., no DC component) flows through the sine wave oscillators 16a / 16b (including resistor 20a), capacitor 18a, blocking inductor 14a, generators 12a-12b, blocking inductor 14b, capacitor 18b, and returns to the sine wave oscillators 16a / 16b. A larger second portion of AC current flows through the sine wave oscillators 16a / 16b (including resistor 20a), capacitor 18a, load 10, capacitor 18b, and returns to the sine wave oscillators 16a / 16b.

[0017] The AC current flowing through the load 10 is measured using a floating sensor 21 that measures the voltage drop across resistor 20a. Sensor 21 includes a voltage follower, a differential amplifier, and a filter (a bandpass filter connected to signal I*GI and circuit 32, and / or a bandpass filter connected to signal I*GI via a multiplexer and circuit 33). When the first and third portions of the AC current are sufficiently small compared to the second portion, such that the voltage drop across resistor 20a is mainly caused by the AC current flowing through the load 10 (i.e., the second portion of the AC current), this estimate can be used as the current flowing through the load 10.

[0018] Terminal A + The AC component of the voltage at terminal B is measured via floating sensor 28, which includes a feedback capacitor, a voltage follower, a differential amplifier, and a filter (a bandpass filter connected to signal V*GV and circuit 32, or a bandpass filter connected to signal V*GV via a multiplexer and circuit 33). - The AC component of the voltage at terminal A + It is estimated that the AC component of the voltage at

[0019] The voltage V*GV, source S, and current I*GI signals are fed to a demodulator 32, which provides an accurate method of calculating the phase of the current and voltage. In this example, demodulator 32 includes a pair of analog multipliers, each connected in series with a low-pass filter. Using the analog signals V*GV, I*GI, and S, demodulator 32 generates two analog signals: 1 / 2|V*GV|.|S|×COSφ(V*GV / S) and 1 / 2|I*GI|.|S|×COSφ(I*GI / S).

[0020] In this example, the monitoring unit 34 also includes a rectifier 33 which, after a low-pass filter, generates one of three analog signals depending on the state of the multiplexer: |V*GV|, |I*GI|, and |S|.

[0021] Microcontroller 24 digitizes the two analog signals generated by demodulator 32 and the two analog signals generated by rectifier 33. Microcontroller 24 has known formulas programmed into its firmware to calculate the capacitance / impedance of load 10 from the digital data. However, in some cases, injecting a sinusoidal signal differentially through capacitors 18a-18b in a bipolar system may not be flexible enough for the power supplies used in some e-chucks.

[0022] 3 represents one phase of a multipolar system. It has terminals 26 connected to load 10. It includes generator 12 and monitoring section 34.

[0023] In this example, the monitoring section 34 includes a sinusoidal oscillator 16 for applying a sinusoidal signal through a transformer 19 placed in series with the load. An RLC circuit 15 is used to resonate at the frequency of the sinusoidal signal and provide a low impedance path to earth for the injected AC current.

[0024] As a result of the combined action of the sinusoidal oscillator 16, the transformer 19 and the RLC circuit 15, a small first portion of AC current (i.e., no DC component) flows through the HV generator 12. A large second portion of AC current is supplied from earth by the current-to-voltage converter 20 and flows through the RLC circuit 15, the secondary coil of the voltage converter 19 and the load 10, and back to earth.

[0025] The AC current through the load 10 is estimated using a sensor including a current-to-voltage converter 20 and a filter (a 90 deg lag filter connected to the I*GI signal and circuit 32, and / or a bandpass filter connected to the I*GI signal and circuit 33). When the first portion of the AC current is sufficiently small compared to the second portion, this estimate can be used as the current through the load 10.

[0026] The AC component of the voltage at the terminals of the load 10 is estimated via a sensor 28, which is adapted to monitor the voltage drop across the primary coil of the voltage transformer 19. The voltage sensor 28 includes an amplifier and a filter (a 90° lag filter connected to the V*GV signal and a circuit 32, and / or a bandpass filter connected to the V*GV signal and a circuit 33). Using the voltage transformation ratio of the voltage transformer 19 (e.g., 1:1), this estimate can be used as the AC component of the voltage at the terminals of the load 10.

[0027] The voltage V*GV, source S, and current I*GI signals are fed to a demodulator 32, which provides an accurate method of calculating the phase of the current and voltage. In this example, demodulator 32 includes a pair of analog multipliers, each connected in series with a low-pass filter. Using the analog signals V*GV, I*GI, and S, demodulator 32 generates two analog signals: 1 / 2|V*GV|.|S|×COSφ(V*GV / S) and 1 / 2|I*GI|.|S|×COSφ(I*GI / S).

[0028] In this example, the monitoring unit 34 also includes a rectifier 33, which, after a low-pass filter, generates one of three analog signals: |V*GV|, |I*GI|, and |S|.

[0029] The microcontroller 24 digitizes the two analog signals generated by the demodulator 32 and the two analog signals generated by the rectifier 33. The microcontroller 24 has known mathematical formulas programmed into its firmware to calculate the capacitance / impedance of the load 10 from the digital data.

[0030] Therefore, there is a need in the art for a power supply that can monitor the impedance or capacitance of a connected load. Summary of the Invention

[0031] The present disclosure provides a power supply capable of monitoring the impedance or capacitance of a connected load. The power supply includes a current sensor adapted to generate a first AC signal indicative of an oscillating current through the load, a voltage sensor adapted to generate a second AC signal indicative of an oscillating voltage across the load, and a source conductor adapted to output a third AC signal indicative of a sinusoidal voltage generated by a sinusoidal oscillator. A microcontroller is coupled to the first AC signal, the second AC signal, and the third AC signal. The microcontroller is adapted to calculate the impedance or capacitance of the load using digital data derived from the first AC signal, the second AC signal, and the third AC signal.

[0032] While the invention is susceptible to various modifications and alternative constructions, specific embodiments thereof have been shown by way of example in the drawings and description, it being understood, however, that the drawings and description are not intended to limit the invention to the particular forms disclosed, but on the contrary, the invention is intended to cover all modifications, equivalents, and alternatives available to those skilled in the art. [Brief explanation of the drawings]

[0033] For a more detailed description of the embodiments of the present disclosure, reference is made to the accompanying drawings. [Figure 1]FIG. 1 is a schematic diagram of a known bipolar power supply suitable for use with a Coulomb chuck. [Figure 2a] 1 is a partial schematic diagram of a known bipolar power supply suitable for use with a Coulomb chuck. [Figure 2b] 1 is another partial schematic diagram of a known bipolar power supply suitable for use with a Coulomb chuck. [Figure 3] 1 is a schematic diagram of one known single phase or multi-phase power supply suitable for use with a Coulomb chuck. [Figure 4] FIG. 1 is a schematic diagram of a single phase or multi-phase power supply suitable for use with a Coulomb chuck. DETAILED DESCRIPTION OF THE INVENTION

[0034] <Detailed explanation> Figure 4 shows a preferred embodiment of a power supply comprising a monitoring unit capable of generating voltage oscillations across a load connected to the power supply and current voltage oscillations flowing into the load from a predetermined sinusoidal signal. sine wave signal, the amplitude and phase shift of the voltage produced by the sinusoidal signal relative to the sinusoidal signal; and The amplitude and phase shift of the current caused by the sinusoidal signal relative to the sinusoidal signal is The monitoring unit calculates the capacitance or impedance of the load based on these measurements, which may be exact or approximate.

[0035] This preferred embodiment may provide a simpler and more efficient method of calculating the capacitance or impedance of a load than the power supply shown in FIGS.

[0036] The power supply shown in FIG. 4 is one of unipolar or multipolar (multiphase) type, with terminals 26 connected to the load 10, and includes a generator 12 and a monitoring section 34.

[0037] In this example, the monitoring section 34 includes a sine wave oscillator 16 for injecting a sine wave signal via a capacitor 18. A blocking inductor 14 is used to increase the impedance of the generator 12 at the frequency of the sine wave oscillator 16.

[0038] As a result of the combined action of the sine wave oscillator 16, capacitor 18, and blocking inductor 14, a small first portion of AC current (i.e., no DC component) flows through the sine wave oscillator 16, capacitor 18, blocking inductor 14, generator 12, and to ground. A large second portion of AC current flows through the sine wave oscillator 16, capacitor 18, load 10, and to ground. A small third portion of AC current flows through the sine wave oscillator 16, capacitor 18, sensor 28, and to ground.

[0039] The second part of the AC current is measured using a sensor 21, which includes a current transformer (which also provides high voltage isolation), an amplifier, and a filter. The second part of the AC current is the exact AC component of the current flowing through the load 10.

[0040] The AC component of the voltage at terminal 26 is measured via sensor 28, which includes a capacitor, a voltage divider, an amplifier, and a filter. This measurement can be used as the AC component of the voltage at terminal 26, since the voltage difference across the primary coil of the current transformer of sensor 21 is negligible.

[0041] The voltage V, source S, and current I signals are fed to a quadrature demodulator 32, which provides a method for accurately calculating the amplitude and phase of the current and voltage. Using the V, I, and S analog signals, demodulator 32 generates four analog signals: |V|.cosφ(V / S), |V|.sinφ(V / S), |I|.cosφ(I / S), and |I|.sinφ(I / S).

[0042] The microcontroller 24 digitizes the four signals with an ADC 24a. The microcontroller 24 has known mathematical formulas programmed into its firmware to calculate the capacitance / impedance of the load 10 from the digital data.

[0043] In a multipolar power supply having an architecture similar to that shown in Figure 4, multiple monitoring units 34 may be used, each measuring the capacitance / impedance of multiple terminals relative to ground. In such a case, it is also possible to calculate a differential capacitance / impedance, for example, by using a combination of different sensors at different terminals.

[0044] In addition to the above, the present disclosure also contemplates at least the following embodiments 1 to 14. Note that all elements in all of these embodiments may further include details relating to that element disclosed in a paragraph or figure describing the preferred embodiment, without including details of other elements disclosed in the same or different paragraphs or figures.

[0045] First Embodiment The first embodiment is a power supply that can monitor the impedance or capacitance of a connected load.

[0046] The power supply includes at least a first terminal connectable to a load, and also includes at least one generator for generating a high direct current (DC) voltage between the first terminal and a second terminal.

[0047] If only one generator is used, the power supply is unipolar. In such a case, the first terminal of the generator is connected to the first terminal of the power supply and the second terminal of the generator is connected to earth.

[0048] If two generators are used, the power supply may be bipolar. In such a case, the power supply further includes a second terminal. The first terminal of the first generator is again connected to the first terminal of the power supply, and the second terminal of the first generator is again connected to ground. In addition, the first terminal of the second generator may be connected to ground, and the second terminal of the second generator is connected to the second terminal of the power supply.

[0049] The power supply is characterized by a monitoring section having an inject circuit, a boost circuit and a sine wave oscillator. If the power supply is bipolar, the monitoring section may also have another boost circuit.

[0050] The injector circuit is adapted to pass an oscillating current between a first terminal and a second terminal, the first terminal of the injector circuit being connected to a first terminal of the power source and the second terminal of the injector circuit being connected to ground or, if present, to the second terminal of the power source, such that the injector circuit is connected to the generator in parallel with the load.

[0051] The boost circuit is adapted to generate an oscillating voltage between a first terminal and a second terminal. The first terminal of the boost circuit is connected to a first terminal of the first generator and the second terminal of the boost circuit is connected to a first terminal of the power source. If present, another boost circuit may be connected between the second terminal of the second generator and the second terminal of the power source. Thus, the boost circuit is connected with the generator in series with the load.

[0052] The sinusoidal oscillator is adapted to generate a sinusoidal voltage at a predetermined frequency. As opposed to a voltage with a different frequency spectrum, a sinusoidal voltage is preferred when the load has a frequency-dependent impedance, such as the impedance of a capacitive circuit (e.g., an electrostatic chuck). Therefore, the load response to a sinusoidal signal at a predetermined frequency is easier to interpret. However, the sinusoidal oscillator may be adapted to generate a sinusoidal voltage at a first predetermined frequency, then sequentially generate a sinusoidal voltage at a second, different frequency, and so on. The sinusoidal oscillator is coupled to one of an inject circuit and a boost circuit. If the sinusoidal oscillator is coupled to the inject circuit, it drives an oscillating current through the load. The boost circuit passively generates an oscillating voltage that tends to cancel the oscillating current, thereby reducing the oscillating current through the generator. If the sinusoidal oscillator is coupled to the boost circuit, it drives an oscillating voltage applied to the load. The inject circuit passively generates an oscillating current which tends to counteract or flow into the generator the oscillating current generated by the load in response to the oscillating voltage, so that less oscillating current also flows through the generator.

[0053] The power supply is further characterized by a current sensor, a voltage sensor, and a source conductor, each of which generates an AC signal used by the microcontroller to calculate the impedance or capacitance of the load.

[0054] The current sensor is adapted to generate a first AC signal indicative of the oscillating current. In general, the current sensor may be adapted to convert a current flowing through a first terminal of the injector circuit or power supply into a voltage.

[0055] The voltage sensor is adapted to generate a second AC signal indicative of the oscillating voltage. Generally, the voltage sensor does not need to be sensitive to the high DC voltage generated by the generator.

[0056] The source conductor is adapted to output a third AC signal indicative of the sinusoidal voltage generated by the sine wave generator.

[0057] The microcontroller may be integrated into the power supply or may exist as a separate module. The microcontroller is coupled to the first AC signal, the second AC signal, and the third AC signal. Optionally, the microcontroller may be coupled to the first AC signal, the second AC signal, and the third AC signal sequentially via a multiplexer. Alternatively, the microcontroller may be coupled to these signals simultaneously. The microcontroller's coupling to these signals may be direct digitized communication of the three AC signals to the microcontroller or indirect digitized communication of another signal derived from the three AC signals to the microcontroller. For example, the other signal may be derived by analog demodulation, rectification, filtering (e.g., band-pass filtering at a predetermined frequency), or a combination thereof.

[0058] Furthermore, the microcontroller is adapted to calculate the impedance or capacitance of the load from digital data derived from the first AC signal, the second AC signal, and the third AC signal. Typically, the microcontroller may be programmable and the calculation of the impedance or capacitance of the load may be pre-programmed to implement mathematical formulas well known in the art.

[0059] In particular, the use of the third AC signal, or an AC signal derived from the third AC signal, may advantageously improve the precision and / or accuracy of the calculation of the impedance or capacitance of the load, typically in the presence of noise in the direct current (DC) high voltage.

[0060] Second Embodiment The second embodiment is the power supply described in the first embodiment, (i) the inject circuit includes a coupling capacitor having one lead connected to the first terminal of the power supply; (ii) the boost circuit includes a blocking inductor and, optionally, a bypass resistor; (iii) the sine wave oscillator includes a first terminal connected to the other lead of the coupling capacitor and a second terminal connected to a second terminal of the power supply or to earth; (iv) A blocking inductor is connected between the first terminal of the generator and the coupling capacitor.

[0061] <Third embodiment> The third embodiment is the power supply described in the first embodiment and is described as follows.

[0062] (i) The inject circuit includes an LC circuit resonating at a predetermined frequency, or optionally an RLC circuit resonating at a predetermined frequency, the inject circuit having a first terminal connected to a first terminal of a power source, and the inject circuit having a second terminal connected to a second terminal of the power source or connected to earth.

[0063] (ii) The boost circuit includes a transformer having a secondary winding connected between a first terminal of the generator and a first terminal of the power source.

[0064] (iii) A sinusoidal oscillator is connected to the primary winding of a transformer.

[0065] (iv) The first terminal of the RLC circuit is connected between the first terminal of the generator and the secondary winding of the transformer.

[0066] <Fourth embodiment> A fourth embodiment is the power supply according to any one of the first to third embodiments, wherein the monitoring unit further includes an analog demodulator.

[0067] The analog demodulator has inputs coupled to the current sensor, the voltage sensor, and the source conductor, and has an output coupled to the microcontroller.

[0068] The analog demodulator is configured to analog demodulate the first and second AC signals into a third AC signal. In other words, the output of the analog demodulator is an analog signal that may have a certain polarity and amplitude that indicates the phase difference between the first and third AC signals or the phase difference between the second and third AC signals. For example, the output of the analog demodulator may have an amplitude that is proportional to the cosine or sine of either the phase difference between the first and third signals or the phase difference between the second and third signals. In particular, the use of an analog demodulator may advantageously simplify digitization of the signal before use by the microcontroller.

[0069] Optionally, the monitoring portion may also include one or more rectifiers having inputs coupled to the first AC signal, the second AC signal, and / or the third AC signal.

[0070] Typically, the output of the analog demodulator and one or more rectifiers is low-pass filtered and digitized by a converter (i.e., ADC). The digitized signal is then transmitted to a microcontroller.

[0071] Fifth Embodiment A fifth embodiment is the power supply described in the fourth embodiment, in which the analog demodulator includes a quadrature demodulator.

[0072] The quadrature demodulator is configured to generate four output signals as described below.

[0073] (i) the magnitude of the first AC signal multiplied by the cosine of the phase of the first AC signal relative to the third AC signal;

[0074] (ii) the magnitude of the first AC signal multiplied by the sine of the phase of the first AC signal relative to the third AC signal;

[0075] (iii) the magnitude of the second alternating current signal multiplied by the cosine of the phase of the second alternating current signal relative to the third alternating current signal; and

[0076] (iv) the magnitude of the second AC signal multiplied by the sine of the phase of the second AC signal relative to the third AC signal;

[0077] In this embodiment, one or more rectifiers may be omitted.

[0078] Sixth Embodiment A sixth embodiment is the power supply described in the fourth embodiment, in which the analog demodulator includes a first analog multiplier, a first low-pass filter connected in series with the first analog multiplier, a second analog multiplier, and a second low-pass filter connected in series with the second analog multiplier.

[0079] The first analog multiplier is configured to generate a product of the first AC signal and the third AC signal, and similarly, the second analog multiplier is configured to generate a product of the second AC signal and the third AC signal.

[0080] In this embodiment, the monitoring unit further includes one or more rectifiers, each connected in series with a corresponding low-pass filter, and the one or more rectifiers are connectable (e.g., directly or via a multiplexer) to one or more of the first AC signal, the second AC signal, and the third AC signal.

[0081] Seventh Embodiment A seventh embodiment is a power supply according to any of the first to sixth embodiments, wherein the current sensor includes a current transformer having a primary coil connected in series between the boost circuit and the first terminal of the power supply, and a secondary coil connected to a resistor and the input of an operational amplifier. The operational amplifier is wired as an inverting or non-inverting operational amplifier with a fixed gain. The terms "inverting operational amplifier" and "non-inverting operational amplifier" used herein are technical terms referring to well-known configurations.

[0082] Eighth Embodiment An eighth embodiment is a power supply according to any of the first to sixth embodiments, wherein the inject circuit includes a resistor through which the oscillating current flows, and the current sensor is adapted to monitor the voltage drop across the resistor. Typically, the current sensor includes a first operational amplifier having an input connected to the high side of the resistor and wired as a voltage follower, and a second operational amplifier having an input connected to the output of the first operational amplifier and wired as a differential amplifier. As used herein, "voltage follower" and "differential amplifier" are terms of art that refer to well-known configurations.

[0083] Ninth Embodiment A ninth embodiment is a power supply according to any of the first to sixth embodiments, wherein the current sensor includes an operational amplifier having an input connected in series with the injector circuit, the operational amplifier being wired as a current-to-voltage converter. As used herein, "current-to-voltage converter" is a term of art that refers to a well-known configuration.

[0084] Tenth Embodiment A tenth embodiment is the power supply according to any of the first to ninth embodiments, wherein the voltage sensor includes a low-pass or band-pass filter connected to the first terminal of the power supply and to ground, and an inverting or non-inverting operational amplifier having an input connected to the low-pass or band-pass filter. Preferably, the low-pass or band-pass filter has a high impedance (i.e., an impedance substantially higher than the impedance of the inject circuit) so that the current drawn by the voltage sensor is negligible.

[0085] For example, a voltage sensor may include a feedback capacitor connected to a first terminal of a power supply and an operational amplifier having an input connected to the feedback capacitor, either directly or indirectly through a resistor. Typically, the operational amplifier is wired as an inverting or non-inverting operational amplifier with a fixed gain. As used herein, "inverting operational amplifier" and "non-inverting operational amplifier" are terms of the art that refer to well-known configurations. Additionally, the input of the operational amplifier may be connected to ground through another resistor.

[0086] Eleventh Embodiment An eleventh embodiment is a power supply according to any of the first to ninth embodiments, wherein the voltage sensor includes a feedback capacitor connected to a first terminal of the power supply, a first operational amplifier connected to the feedback capacitor and wired as a voltage follower, and a second operational amplifier connected to the output of the first operational amplifier and wired as a differential amplifier. As used herein, "voltage follower" and "differential amplifier" are technical terms that refer to well-known configurations.

[0087] <Twelfth embodiment> A twelfth embodiment is the power supply according to any of the first to ninth embodiments, wherein the boost circuit includes a transformer having a primary coil and a secondary coil connected in series between the injector circuit and the first terminal of the power supply, and the voltage sensor is adapted to monitor the voltage drop across the primary coil. Typically, the voltage sensor includes an operational amplifier wired as an inverting or non-inverting operational amplifier with a fixed gain. The terms "inverting operational amplifier" and "non-inverting operational amplifier" used herein are terms of the art that refer to well-known configurations.

[0088] For example, the transformer may be a 1:1 transformer, in which case the oscillating voltage is in a 1:1 ratio with the voltage monitored by the voltage sensor before the amplification gain is applied.

[0089] <Thirteenth embodiment> A thirteenth embodiment is a method of monitoring the impedance or capacitance of a load connected to a power supply, the method comprising the steps of providing a power supply according to any of the first to twelfth embodiments and providing monitoring to display or store digital data indicative of the impedance or capacitance of the load.

[0090] <Fourteenth embodiment> A fourteenth embodiment is the method described in the thirteenth embodiment, wherein the load is a Coulomb-type electrostatic chuck, and the method further includes clamping the semiconductor or liquid crystal panel by applying a direct current (DC) high voltage to the chuck using a power supply.

Claims

1. a power source, The impedance or capacitance of a load connected to the power supply may be monitored; The power supply a first terminal connectable to the load; a generator adapted to generate a direct current (DC) high voltage between a first terminal and a second terminal, the first terminal of the generator being connected to a first terminal of the power source and the second terminal of the generator being connected to earth; A monitoring department; and The monitoring unit an inject circuit adapted to pass an oscillating current between a first terminal and a second terminal, the first terminal of the inject circuit being connected to a first terminal of the power supply and the second terminal of the inject circuit being connected to ground or to the second terminal of the power supply; a boost circuit adapted to generate an oscillating voltage between a first terminal and a second terminal, the first terminal of the boost circuit being connected to a first terminal of the generator and the second terminal of the boost circuit being connected to a first terminal of the power source; a sine wave oscillator adapted to generate a sine wave voltage at a predetermined frequency, the sine wave oscillator having a terminal coupled to one of the inject circuit and the boost circuit; a current sensor adapted to generate a first AC signal indicative of the oscillating current, the current sensor comprising a transformer having a primary coil connected in series between the boost circuit and a first terminal of the power supply, and a secondary coil connected to an input of an inverting or non-inverting operational amplifier; a voltage sensor adapted to generate a second AC signal indicative of the oscillating voltage; a source conductor adapted to output a third AC signal indicative of the sinusoidal voltage; a microcontroller coupled to the first AC signal, the second AC signal, and the third AC signal, the microcontroller adapted to calculate an impedance or a capacitance of the load using digital data derived from the first AC signal, the second AC signal, and the third AC signal. power supply.

2. 10. The power supply of claim 1, The inject circuit a coupling capacitor having one lead connected to the first terminal of the power supply; The sine wave oscillator comprises: a first terminal connected to the other lead of the coupling capacitor, and a second terminal connected to ground or to a second terminal of the power supply; The boost circuit comprises: a blocking inductor; the blocking inductor is connected between the first terminal of the generator and the coupling capacitor; power supply.

3. 10. The power supply of claim 1, an analog demodulator having inputs coupled to the current sensor, the voltage sensor, and the source conductor; The analog demodulator an output coupled to the microcontroller; configured to analog-demodulate the first AC signal and the second AC signal with respect to the third AC signal; power supply.

4. 4. The power supply of claim 3, The analog demodulator a quadrature demodulator configured to generate four output signals; The four output signals are: the magnitude of the first AC signal multiplied by the cosine of the phase of the first AC signal relative to the third AC signal; the magnitude of the first AC signal multiplied by the sine of the phase of the first AC signal relative to the third AC signal; the magnitude of the second AC signal multiplied by the cosine of the phase of the second AC signal relative to the third AC signal; the magnitude of the second AC signal multiplied by the sine of the phase of the second AC signal relative to the third AC signal; power supply.

5. 10. The power supply of claim 1, The voltage sensor a low-pass or band-pass filter connected to the first terminal of the power supply and to ground; an inverting or non-inverting operational amplifier having an input connected to the low-pass or band-pass filter; power supply.

6. 1. A method for monitoring the impedance or capacitance of a load connected to a power source, comprising: The power supply a first terminal connectable to the load; and a generator adapted to generate a direct current (DC) high voltage between the first terminal and a second terminal, the first terminal of the generator being connected to a first terminal of the power source and the second terminal of the generator being connected to earth; The method comprises: providing a monitoring unit for the power supply; causing the monitoring unit to display or store digital data indicative of the impedance or capacitance of the load; Including, The monitoring unit an inject circuit adapted to pass an oscillating current between a first terminal and a second terminal, the first terminal of the inject circuit being connected to a first terminal of the power supply, and the second terminal of the inject circuit being connected to ground or to the second terminal of the power supply; a boost circuit adapted to generate an oscillating voltage between a first terminal and a second terminal, the first terminal of the boost circuit being connected to a first terminal of the generator and the second terminal of the boost circuit being connected to a first terminal of the power source; a sine wave oscillator adapted to generate a sine wave voltage at a predetermined frequency, the sine wave oscillator having a terminal coupled to one of the inject circuit and the boost circuit; a current sensor adapted to generate a first AC signal indicative of the oscillating current, the current sensor comprising a transformer having a primary coil connected in series between the boost circuit and a first terminal of the power supply, and a secondary coil connected to an input of an inverting or non-inverting operational amplifier; a voltage sensor adapted to generate a second AC signal indicative of the oscillating voltage; and, a source conductor adapted to output a third AC signal indicative of the sinusoidal voltage; a microcontroller coupled to the first AC signal, the second AC signal, and the third AC signal, the microcontroller adapted to calculate an impedance or a capacitance of the load using digital data derived from the first AC signal, the second AC signal, and the third AC signal. method.

7. 7. The method of claim 6, The inject circuit a coupling capacitor having one lead connected to the first terminal of the power supply; The sine wave oscillator comprises: a first terminal connected to the other lead of the coupling capacitor, and a second terminal connected to ground or to a second terminal of the power supply; The boost circuit comprises: a blocking inductor; the blocking inductor is connected between the first terminal of the generator and the coupling capacitor; method.

8. 7. The method of claim 6, an analog demodulator having inputs coupled to the current sensor, the voltage sensor, and the source conductor; The analog demodulator an output coupled to the microcontroller; configured to analog-demodulate the first AC signal and the second AC signal with respect to the third AC signal; method.

9. 9. The method of claim 8, The analog demodulator a quadrature demodulator configured to generate four output signals; The four output signals are: the magnitude of the first AC signal multiplied by the cosine of the phase of the first AC signal relative to the third AC signal; the magnitude of the first AC signal multiplied by the sine of the phase of the first AC signal relative to the third AC signal; the magnitude of the second AC signal multiplied by the cosine of the phase of the second AC signal relative to the third AC signal; the magnitude of the second AC signal multiplied by the sine of the phase of the second AC signal relative to the third AC signal; method.

10. 7. The method of claim 6, The voltage sensor a low-pass or band-pass filter connected to the first terminal of the power supply and to ground; an inverting or non-inverting operational amplifier having an input connected to the low-pass or band-pass filter; method.

11. 7. The method of claim 6, The load is It is a Coulomb type electrostatic chuck, The method comprises: further comprising clamping a semiconductor or liquid crystal panel by applying a direct current (DC) high voltage to the chuck using the power supply. method.

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