Multi-range voltage sensor and method for a voltage controlled interface of a plasma processing system

A voltage sensor for a voltage controlled interface of a plasma processing system. The voltage sensor receives a RF signal generated by a pickup device. The RF signal is indicative of a RF voltage provided at a substrate in a plasma chamber. The voltage sensor includes first and second dividers corresponding to first and second channels and having first and second capacitance ratios. The dividers receive the RF signal and respectively generate first and second reduced voltage signals. A first output of the first channel outputs a first output signal based on the first reduced voltage signal and while the RF signal is in a first voltage range. A second output of the second channel outputs a second output signal based on the second reduced voltage signal and while the RF signal is in a second voltage range.

FIELD

The present disclosure relates to plasma processing systems and, more particularly, detecting voltages in an electrostatic chuck of a plasma processing system.

BACKGROUND

Ionized gas, or plasma, is commonly used during the processing and fabrication of semiconductor devices. For example, plasma can be used to etch or remove material from a substrate such as a semiconductor wafer, and to sputter or deposit material onto the substrate. Creating plasma for use in manufacturing or fabrication processes typically begins by introducing process gases into a processing chamber. The substrate is disposed in the processing chamber on a substrate support such as an electrostatic chuck or a pedestal.

The processing chamber may include a transformer coupled plasma (TCP) reactor coil. A radio frequency (RF) signal, supplied by a power supply, is supplied to the TCP reactor coil. A dielectric window, constructed of a material such as ceramic, is incorporated into an upper surface of the processing chamber. The dielectric window allows the RF signal from the TCP reactor coil to be transmitted into the interior of the processing chamber. The RF signal excites gas molecules within the processing chamber to generate plasma.

The plasma includes electrons and positively charged particles. The electrons, being lighter than the positively charged particles, tend to migrate more readily, causing a sheath to form at surfaces of the processing chamber. A self-biasing effect causes a net negative charge at inner surfaces of the processing chamber. This net negative charge is provided relative to ground (referred to as a direct current (DC) bias) and relative to a potential of the plasma (referred to as DC sheath potential). The DC bias is a difference in electrical potential between a surface within the processing chamber and ground. The DC sheath potential is a difference between the potential of the surface within the processing chamber and the potential of the plasma. The DC sheath potential causes the heavier positively charged particles to be attracted towards the inner surfaces of the processing chamber. Strength of this DC sheath potential at the substrate largely determines the energy with which the positively charged particles strike the substrate. This energy affects process characteristics such as an etch rate or a deposition rate.

A bias RF power source supplies a biasing RF signal to the substrate support. The biasing RF signal can be used to increase the DC bias and/or the DC sheath potential to increase the energy with which the charged particles strike the substrate. Variations in the biasing RF signal produce corresponding variations in the DC bias and/or DC sheath potential at the substrate affecting the process characteristics.

A pickup device may be attached to the substrate support and is used to detect an RF peak voltage at the substrate support. A RF voltage sensor is connected to the pickup device and detects the RF peak voltage. The biasing RF signal may be adjusted based on the detected RF peak voltage to minimize variations in the DC bias and/or the DC sheath potential at the substrate.

SUMMARY

A voltage sensor is provided and is configured for a voltage controlled interface of a plasma processing system. The voltage sensor is configured to receive a RF signal generated by a pickup device. The received RF signal is indicative of a RF voltage provided at a substrate in a plasma chamber. The voltage sensor includes: a first divider corresponding to a first channel and having a first capacitance ratio; a second divider corresponding to a second channel and has a second capacitance ratio, a first output of the first channel and a second output of the second channel. The first divider is configured to receive the RF signal generated by the pickup device. The first divider generates a first reduced voltage signal. The second divider is configured to receive the RF signal generated by the pickup device. The second divider generates a second reduced voltage signal. The first output of the first channel is configured to output a first output signal based on the first reduced voltage signal and while the received RF signal is in a first voltage range. The second output of the second channel is configured to output a second output signal based on the second reduced voltage signal and while the received RF signal is in a second voltage range. The second voltage range is different than the first voltage range.

A method of operating a voltage sensor is also provided. The voltage sensor is configured for a voltage controlled interface of a plasma processing system. The voltage sensor is configured to receive a RF signal generated by a pickup device. The received RF signal is indicative of a RF voltage provided at a substrate in a plasma chamber. The method includes: receiving the RF signal generated by the pickup device at a first divider of a first channel, wherein the first divider has a first capacitance ratio; generating a first reduced voltage signal via the first divider; receiving the RF signal generated by the pickup device at a second divider of a second channel, wherein the second divider has a second capacitance ratio; and generating a second reduced voltage signal via the second divider. The method further includes: providing a first output signal via the first channel based on the first reduced voltage signal and while the received RF signal is in a first voltage range; and providing a second output signal via a the second channel based on the second reduced voltage signal and while the received RF signal is in a second voltage range, wherein the second voltage range is different than the first voltage range.

DETAILED DESCRIPTION

A traditional RF voltage sensor may provide a linear output for one voltage range (e.g., 1000-2000 volts (V)). The same RF sensor however may provide a non-linear output for other voltage ranges (e.g., voltages from 0 to 1000 volts (V)). Thus, the linear operating range of the RF voltage sensor is limited. The following examples disclose RF voltage sensor circuits having linear responses for multiple operating voltage ranges. In other words, the RF voltage sensors provide linear output response signals based on detected voltages over multiple operating voltage ranges.

FIG. 1shows a plasma processing system10that includes a plasma processing chamber12and a transformer coupled plasma (TCP) reactor coil14. The TCP reactor coil14is disposed outside and above the plasma processing chamber12. The first power source16provides a first RF source signal. A first match network18is included between the first power source16and the TCP reactor coil14. The plasma processing chamber12includes a ceramic window19, which is located adjacent the TCP reactor coil14and allows efficient transmission of the first RF source signal into the plasma processing chamber12for plasma generation purposes.

The plasma processing system10further includes a substrate support20such as an electrostatic chuck, a pedestal or other suitable substrate support, located at the bottom of the plasma processing chamber12. The substrate support20supports a substrate22. If the substrate support20is an electrostatic chuck, the substrate support20includes electrically conductive portions24and26, which are electrically isolated from each other. The substrate support20is surrounded by an insulator28and is capacitively coupled to the substrate22. By applying a DC voltage across the conductive portions24,26, an electrostatic coupling is created between the conductive portions24,26and the substrate22. This electrostatic coupling attracts the substrate22against the substrate support20.

The plasma processing system10further includes a bias RF power source30, which is connected to a second match network32. The second match network32is connected between the bias RF power source30and the substrate support20. The second match network32matches an impedance (e.g.,500) of the bias RF power source30to an impedance of the substrate support20and plasma34in the plasma processing chamber12as seen by the second matching network32.

The plasma processing system10further includes a voltage control interface (VCI)40. The VCI40may include a pickup device42, a multi-range voltage sensor44(referred to hereinafter as “the voltage sensor”), a controller46and any circuitry between the voltage sensor44and the controller46. The pickup device42extends into the substrate support20. This pickup device42is connected via a wire48to the voltage sensor44and is used to generate a RF voltage signal. The voltage sensor44is configured to detect peak voltages in the RF voltage signal for multiple voltage ranges. The voltage sensor44has multiple channels. The channels are allocated to corresponding ranges of input voltages received from the pickup device42. Each of the channels provides a linear output response for a corresponding input voltage range.

The voltage sensor44generates output signals, which may be monitored and/or used to adjust a biasing RF signal (or second RF source signal) generated by the bias RF power source30. Each of the channels has a linear response to changes in peak voltages of the RF voltage signal received from the pickup device42, such that a relationship between values of the output signals and changes in the peak voltage of the RF voltage signal is linear. The output signals may include cross-check signals for determining whether an error exists with one or more of the channels.

Operation of the voltage sensor44may be monitored, manually controlled, and/or controlled via the controller46. The controller46may display output voltages of the channels of the voltage sensor44on a display50. Although shown separate from the controller46, the display50may be included in the controller46. A system operator may provide input signals indicating (i) whether to switch between the channels, (ii) which one or more of the channels to activate, and/or (ii) which one or more of the channels to deactivate. The controller46may receive the input signals from an input device52and control operation of the voltage sensor44based on the input signals. Although shown separate from the controller46, the input device52may be included in the controller46. As an alternative, the controller46may receive the output signals from the voltage sensor44and based on the output signals control operation of the voltage sensor44. This may include activating and deactivating one or more of the channels. Operation of the voltage sensor44is further described below with respect toFIGS. 2-4.

In operation, a gas capable of ionization flows into the plasma processing chamber12through the gas inlet56and exits the plasma processing chamber12through the gas outlet58. The first RF signal is generated by the RF power source16and is delivered to the TCP reactor coil14. The first RF signal radiates from the TCP reactor coil14through the window19and into the plasma processing chamber12. This causes the gas within the plasma processing chamber12to ionize and form the plasma34. The plasma34produces a sheath60along walls of the plasma processing chamber12. The plasma34includes electrons and positively charged ions. The electrons, being much lighter than the positively charged ions, tend to migrate more readily, generating DC bias voltages and DC sheath potentials at inner surfaces of the plasma processing chamber12. An average DC bias voltage and a DC sheath potential at the substrate22affects the energy with which the positively charged ions strike the substrate22. This energy affects processing characteristics such as rates at which etching or deposition occurs.

The controller46may adjust the bias RF signal generated by the RF power source30to change the amount of DC bias and/or a DC sheath potential at the substrate22. The controller46may compare outputs of the channels of the voltage sensor44and/or a representative value derived based on the outputs of the channels to one or more set point values. The set point values may be predetermined and stored in a memory62of the controller46. The bias RF signal may be adjusted based on differences between (i) the outputs of the voltage sensor44and/or the representative value and (ii) the one more set point values. The bias RF signal passes through the second match network32. An output provided by the second match network32(referred to as a matched signal) is then passed to the substrate support20. The bias RF signal is passed to the substrate22through the insulator28.

FIG. 2shows a VCI100that includes a multi-range voltage sensor102(referred to hereinafter as “the voltage sensor”) and the controller46. The VCI100may include the input device52. The voltage sensor102may be used in the plasma processing system10ofFIG. 1and/or replace the voltage sensor44. The voltage sensor102includes multiple channels104,106and a channel switching circuit108. The channel switching circuit108has multiple operating states corresponding to activated and deactivated states of the channels104,106. In the example shown, the voltage sensor102includes two channels. The voltage sensor102may include any number of channels.

The channels104,106include respective alternating current (AC) dividers110,112. The AC dividers110,112include capacitances C1, C2, C3, C4. The first AC divider110includes the capacitances C1, C2connected in series between the pickup device42ofFIG. 1and a ground reference114. The second AC divider112includes the capacitances C3, C4connected in series between the pickup device42and the ground reference114. The first AC divider110is connected in parallel with the second AC divider112.

The AC dividers110,112divide a RF signal received from the pickup device42based on respective capacitance ratios of each of the AC dividers110,112. The capacitance ratio of the first AC divider110may be C2:C1(e.g., 100:1). The capacitance ratio of the second AC divider112may be C4:C3(e.g., 200:1). The first AC divider110may, for example, have a smaller capacitance ratio than the capacitance ratio of the second AC divider112. This provides lower voltages to the first channel and higher voltages to the second channel. Outputs of the AC dividers110,112are provided across respective resistances R1, R2. Resistance R1is connected between an output of the first AC divider110and a ground reference114. Resistance R2is connected between an output of the second AC divider112and the ground reference114.

The channel switching circuit108includes the controller46and diodes D1and D2. The controller46(i) activates the first channel104by forward biasing a diode D1and reverse biasing a diode D2, and (ii) deactivates the first channel104by reverse biasing the diode D1and forward biasing the diode D2. The activation and deactivation of the first channel104is based on output voltages of the first channel104and may be based on output voltages of the second channel106.

The controller46, as shown has two outputs120,122, which provide respective DC voltages when activated. While the VCI100is detecting voltages via the pickup device42in a first range (e.g., 50-1000 peak volts (Vpk)), the first channel104is activated, the first output120provides a first DC voltage (e.g., 24V), and the second output122is deactivated (e.g., at 0V). The controller46may include a first DC power source (one of DC power sources124) to provide the first DC voltage. As an alternative the controller46or a portion thereof may not be included. The first DC power source may be connected to and supply the first DC voltage to the resistance R3and the capacitance C5. The supplying of the first DC voltage provides a positive DC voltage to an anode of the diode D1, which activates the diode D1and allows a first voltage across resistance R1(or RF signal received from the first AC divider110) to be passed through the diode D1. Voltage at a cathode of the diode D2is higher than a voltage at an anode of the diode D2. As a result, the diode D2is deactivated.

While the VCI100is detecting voltages via the pickup device42in a second range (e.g., 100-2000Vpk), the first channel104is deactivated, the first output120is deactivated (e.g., transitioned to 0V), and the second output122provides a second DC voltage (e.g., 24V). The controller46may include a second DC power source (one of DC power sources124) to provide the second DC voltage. As an alternative, the controller46or a portion thereof may not be included. The second DC power source may be connected to and supply the second DC voltage to the resistance R4and the capacitance C6. The second DC power source may be a same or different power source than the first DC power source. The supplying of the second DC voltage provides a positive voltage to the anode of the diode D2and a positive voltage to a cathode of the diode D1. This deactivates the diode D1and activates the diode D2. While the diode D1is deactivated and the diode D2is activated, the voltage across resistance R1(or RF signal received from the first AC divider110) is not permitted to pass through the diode D1and a voltage at a node126between the diodes D1, D2is low or negligible. This provides a low-voltage at an output128of the first channel104, which can be used to indicate that the first channel104is properly deactivated.

The first channel104further includes voltage dividers. The voltage dividers are provided by resistances R3, R4, R5. While the channel switching circuit108is in a first state (e.g., the first channel is activated), the first voltage divider is provided by the resistances R3and R5. While the channel switching circuit108is in a second state (e.g., the first channel is deactivated), the second voltage divider is provided by the resistances R4and R5The voltage dividers limit current and/or voltage at the node126and provided to a first peak detector130. While the first channel104is deactivated (i.e. the diode D1is reversed biased and the diode D2is forward biased), the second output122of the controller46and the second voltage divider effectively operate as a shunt. This minimizes voltage at the node126and voltage at the output128of the first channel104.

The resistance R3is connected between (i) the first output120of the controller46and (ii) the output of the first AC divider110and the diode D1. The capacitance C5(referred to as a bypass capacitance) is connected between (i) the first output120of the controller46and the resistance R3and (ii) the ground reference114. The resistance R4is connected between (i) the second output122of the controller46and (ii) the anode of diode D2. The capacitance C6(referred to as a bypass capacitance) is connected between (i) the second output122of the controller46and the resistance R4and (ii) the ground reference114. The bypass capacitances C5, C6are provided for signal conditioning to, for example, remove noise from the RF signals provided by the AC divider110.

One or more of the resistances R3and R4may be replaced with inductors. In another implementation, inductors are included in addition to the resistances R3and R4. The inductors may be connected in series with the resistances R3and R4. As an example, a first inductor may be connected in series with the resistance R3between (i) the first output120of the controller46and (ii) the anode of the diode D1. A second inductor may be connected in series with the resistance R4between (i) the second output122of the controller46and (ii) the anode of the diode D2. If inductors are used in replacement of or in addition to the resistances R3and/or R4, the resistance R5may be increased, as compared to when the inductors are not incorporated in the VCI100. The inductors may be used to choke off RF current received from the AC divider110.

The channels104,106further include respective peak detectors130,132, converters134,136, and amplifier circuits137,139. The peak detectors130,132include respective diodes D3, D5, capacitances C8, C10and resistances R6, R8. The diode D3receives outputs of the diode D1. A capacitance C7is connected between (i) the diodes D1, D2and (ii) the diode D3. This AC couples an input of the first peak detector130and thus prevents DC from being received by the diode D3. The capacitance C7blocks the DC voltages provided by the controller46and/or portions thereof from being received at the first peak detector130and diode D3. The capacitance C8and the resistance R6are connected in parallel between a cathode of the diode D3and the ground reference114. The capacitance C10and the resistance R8are connected in parallel between a cathode of the diode D5and the ground reference114. Outputs of the peak detectors130,132are provided to the converters134,136.

The converters134,136may amplify and/or convert outputs of the peak detectors130,132to DC voltages. The DC voltages may be provided respectively to amplifier circuits137,139. The amplifier circuits137,139may have respective inputs143,145. The amplifier circuits137,139adjust linearity of the DC voltage signals out of the converters134,136. For example, the amplifier circuits137,139may adjust slope and/or intercept (referred to as offset) of the DC voltage signals out of the converters134,136. The amplifier circuits137,139may include potentiometers147,149, which may be used to adjust the slope and the offset of the DC voltage signals out of the converters134,136. A first potentiometer of each of the amplifier circuits137,139may be used to adjust an input, gain, and/or attenuation of the amplifier circuits137,139and/or of amplifiers included in the amplifier circuits137,139. A second potentiometer of each of the amplifier circuits137,139may be used to adjust an output and/or offset of the amplifier circuits137,139and/or of amplifiers included in the amplifier circuits137,139. The inputs143,145may be manually entered inputs or may be inputs from the controller46. The inputs143may be used to adjust respectively the potentiometers147. The inputs145may be used to adjust respectively the potentiometers149. Incorporation and adjustment of the potentiometers147,149accounts for non-linear behavior of the diodes D3, D5. The amplifier circuits137,139may be separate from the controller46as shown or may be included in the controller46.

The amplifier circuits137,139generate linearity adjusted signals based on the DC output signals. The DC output signals and/or linearity adjusted signals out of the amplifier circuits137,139may be fed back to the controller46, which may adjust operation of the bias RF power source30ofFIG. 1based on the DC voltages, DC output signals, and/or the linearity adjusted signals. The controller46may also activate or deactivate the first channel based on the DC voltages, DC output signals, and/or the linearity adjusted signals fed back to the controller46.

The converters134,136include respective operational amplifiers138,140, capacitances C9, C11, resistances R7, R9, diodes D4, D6, and resistances R10, R11. A non-inverting input of the first operational amplifier138receives the output of the first peak detector130. The capacitance C9, resistance R7and diode D4are connected in parallel across the first operational amplifier138between an inverting input of the first operational amplifier138and an output of the first operational amplifier138. A non-inverting input of the second operational amplifier140receives the output of the second peak detector132. The capacitance C11, resistance R9and diode D6are connected in parallel across the second operational amplifier140between an inverting input of the second operational amplifier140and an output of the second operational amplifier140. Anodes of the diodes D4, D6are connected to the outputs of the operational amplifiers138,140. Cathodes of the diodes D4, D6are connected to the inverting inputs of the operational amplifiers138,140. The outputs of the operational amplifiers138,140provide the DC voltages to amplifier circuits137,139.

The resistance R10is connected between the inverting input of the first operational amplifier138and the ground reference114. The resistance R11is connected between the inverting input of the second operational amplifier140and the ground reference114. The resistances R10, R11are used to set up gain of the operational amplifiers138,140. While the diodes D4, D6are not fully conducting, gain is provided due to incorporation of the resistances R10, R11. This aids in amplification of low-amplitude signals while the diodes D4, D6are not conducting and/or are not fully conducting. While the diodes D4, D6are fully conducting, gain of the converters134,136may be unity gain.

The first channel104may be used for input (or detected) voltages in the first range (e.g., 50-1000Vpk) and provide corresponding DC output voltages (or the linearity adjusted signals) in a third range (e.g., 0.5-10V) at the first output128. The second channel106may be used for input (or detected) voltages in a second range (e.g., 100-2000Vpk) and provide corresponding DC output voltages (or the linearity adjusted signals) in a fourth range (e.g., 0.5-10V) at a second output141. The controller46may switch operating states of the diodes D1, D2based on the DC output voltages (or the linearity adjusted signals) of the channels104,106.

While the VCI100is detecting voltages in the second range, high voltages exist at the output of the AC dividers110,112. While the VCI100is detecting voltages in the second range and the first channel is deactivated, the low-voltage is provided at the node126between the diodes D1, D2. The low-voltage is within an operating range of the first peak detector130and first converter134. The first peak detector130and the first converter134are configured to operate during the detection of voltages in the first range. The second peak detector132and the second converter136are configured to operate during the detection of voltages in the second range. By providing a low-voltage at the node126between the diodes D1, D2, the first peak detector130and the first converter134are protected from receiving high voltages experienced at the output of the first AC divider110.

Although the VCI100is shown such that the second channel106is maintained in an activated state while the first channel104is activated, the VCI100may be modified to deactivate the second channel106while the first channel104is activated. While the first channel104is activated, the second channel106may remain activated to provide a cross-check on the first channel104. The controller46may monitor and compare DC output voltages (or the linearity adjusted signals) of both of the channels104,106.

As an example, a difference between the DC output voltages (or the linearity adjusted signals) and/or a difference between values derived based on the DC output voltages (or the linearity adjusted signals) may (i) confirm that both channels104,106are operating appropriately (i.e. no detected errors), or (ii) indicate one or more of the channels104,106is operating inappropriately and/or one or more errors exist. An error may refer to a problem associated with the pickup, the chuck, the chamber, one of the channels, one or more components of one of the channels, etc. As another example, if the difference between the DC output voltages (or the linearity adjusted signals) of the channels104,106(and/or a difference between values derived based on the DC output voltages or a difference between values derived based on the linearity adjusted signals) is less than or equal to a predetermined value and/or within a first predetermined range, both of the channels104,106may be operating appropriately. If the difference between the DC output voltages (or the linearity adjusted signals) of the channels (and/or a difference between values derived based on the DC output voltages or a difference between values derived based on the linearity adjusted signals) is greater than the predetermined value and/or within a second predetermined range, both of the channels104,106may be operating inappropriately.

The VCI100does not include a cross-check for the second channel106when the first channel is deactivated.FIG. 3shows a VCI150that provides a third channel152, which may be used to cross-check the second channel106. The VCI150is similar to the VCI100ofFIG. 2in that the VCI150also includes a multi-range voltage sensor154and the controller46. The VCI150may include the input device52. The VCI150includes the AC dividers110,112the channel switching circuit108, the peak detectors130,132, the converters134,136, and the amplifier circuits137,139. The AC dividers110,112include the capacitances C1-C4. The channel switching circuit108includes the controller46, the diodes D1and D2, the resistances R3, R4, R5, and the capacitances C5, C6. The peak detectors130,132include the diodes D3, D5, capacitances C8, C10, and resistances R6, R8. The converters134,136include the operational amplifiers138,140, the capacitances C9, C11, the resistances R7, R9, the diodes D4, D6, and the resistances R10, R11.

The third channel152may include a third AC divider153, a third peak detector154, a third converter156, and a third amplifier circuit157. The third AC divider153includes capacitances C12, C13connected in parallel with the AC dividers110,112. The third peak detector154includes diode D7, capacitance C14and resistance R13. An anode of the diode D7is connected to the output of the third AC divider153and to a resistance R12. The resistance R12is connected between the third AC divider153and the ground reference114. The capacitance C14and the resistance R13are connected in parallel between a cathode of the diode D7and the ground reference114.

The third converter156includes a third operational amplifier158, capacitance C15, diode D8, and resistance R15. A non-inverting input of the third operational amplifier158is connected to the cathode of the diode D7and to the capacitance C14and the resistance R13. The capacitance C15, the resistance R14and the diode D8are connected in parallel between an inverting input and an output of the third operational amplifier158. An anode of the diode D8is connected to the output of the third operational amplifier158. A cathode of the diode D8is connected to the inverting input of the third operational amplifier158. The operational amplifier158provides a DC output signal to the third amplifier circuit157.

The resistance R15is connected between the inverting input of the operational amplifier158and the ground reference114. The resistance R15is used to set up a gain of the operational amplifiers158. While the diode D8is not fully conducting, gain is provided due to incorporation of the resistance R15. This aids in amplification of low-amplitude signals while the diode D8is not conducting and/or is not fully conducting. While the diode D8is fully conducting, gain of the converter156may be unity gain.

The third amplifier circuit157adjusts linearity of the DC output signal received from the operational amplifier158. The third amplifier circuit157may include inputs159and potentiometers161. For example, the amplifier circuit157may adjust slope and/or intercept (referred to as offset) of the DC voltage signal out of the converter156. The potentiometers161may be used to adjust respectively the slope and the offset of the DC voltage signal out of the converters156. A first potentiometer may be used to adjust an input, gain, and/or attenuation of the amplifier circuit157and/or of an amplifier included in the amplifier circuit157. A second potentiometer may be used to adjust an output and/or offset of the amplifier circuit157and/or of an amplifier included in the amplifier circuit157. The inputs159may be manually entered inputs or may be inputs from the controller46. The inputs159may be used to adjust respectively the potentiometers161. Incorporation and adjustment of the potentiometers161accounts for non-linear behavior of the diode D7. The amplifier circuit157may be separate from the controller46as shown or may be included in the controller46.

The amplifier circuits137,139,157generate linearity adjusted signals based on the DC output signals. The DC output signals and/or linearity adjusted signals out of the amplifier circuits137,139,157may be fed back to the controller46, which may adjust operation of the bias RF power source30ofFIG. 1based on the DC voltages, DC output signals, and/or the linearity adjusted signals. The controller46may also activate or deactivate the first channel based on the DC voltages, DC output signals, and/or the linearity adjusted signals fed back to the controller46.

The controller46may monitor DC output voltages (or the linearity adjusted signals) of the amplifier circuits137,139,157. The DC output signal (or the linearity adjusted signal) of the third channel152may be used to cross-check the second channel106and/or the first channel104. The third channel152may be used to cross-check the first channel104while the first channel104is activated and may be used to cross-check the second channel106while the first channel104is deactivated. Similarly, the DC output voltage (or the linearity adjusted signal) of the second channel106may be used to cross-check the DC output voltage (or the linearity adjusted signal) of the third channel152. The described cross-checking of channels104,106,152may include comparing DC output voltages (or the linearity adjusted signals) of the channels104,106,152and/or values derived based on the DC output voltages (or the linearity adjusted signals) of the channels104,106,152. Differences between the DC output voltages (or the linearity adjusted signals) of the channels104,106,152and/or values derived based on the DC output voltages (or the linearity adjusted signals) of the channels104,106,152indicate whether the channels104,106,152are operating appropriately or whether one or more errors exist.

The systems disclosed herein may be operated using numerous methods, an example method is illustrated inFIG. 4. InFIG. 4, a method of operating a VCI and a multi-range voltage sensor is shown. Although the following tasks are primarily described with respect to the implementations ofFIGS. 1-3, the tasks may be easily modified to apply to other implementations of the present disclosure. The tasks may be iteratively performed.

The method may begin at200. At202, the AC dividers110,112,153receive a RF voltage signal from the pickup device42on the substrate support20. At204, the first AC divider110generates a first reduced RF signal based on the received RF voltage signal and the first capacitance ratio of the first AC divider110. At206, the second AC divider112generates a second reduced RF signal based on the received RF voltage signal and the second capacitance ratio of the second AC divider112. Task206may be performed while task204is performed. At207, the third AC divider153generates a third reduced RF signal based on the received RF voltage signal and the third capacitance ratio of the third AC divider153. Task207may be performed while task204and/or206are performed.

At208, the first peak detector130generates a first peak voltage signal based on the first reduced RF voltage signal. At210, the second peak detector132generates a second peak voltage signal based on the second reduced RF voltage signal. At212, the third peak detector154generates a third peak voltage signal based on the third reduced RF voltage signal. Tasks210and212may be performed while task208is performed. Task212may be performed while task210is performed.

At214, the first converter134amplifies and converts the first peak voltage signal to a first DC output signal. At216, the second converter136amplifies and converts the second peak voltage signal to a second DC output signal. At218, the third converter156amplifies and converts the third peak voltage signal to a third DC output signal. Tasks216and218may be performed while task214is performed. Task218may be performed while task216is performed.

At219, the amplifier circuits137,139,157may adjust linearity of the DC output voltage signals including adjusting gain, attenuation, and/or offset, as described above. At220, the controller46may receive, display, and/or monitor the DC output voltage signals and/or the linearity adjusted signals from the amplifier circuits137,139,157. The controller46may determine a representative value based on one or more of the DC output voltage signals and/or the linearity adjusted signals. As a first example, the representative value may be a DC output voltage of one of the DC output voltage signals and/or a DC voltage of one of the linearity adjusted signals. The representative value may indicate a peak voltage of the RF voltage signal received at202and may be based on one or more of the DC output voltage signals and/or one or more of the linearity adjusted signals. The representative value may be an average DC output voltage determined based on (i) voltages of one or more of the DC output voltage signals, (ii) voltages of one or more of the linearity adjusted signals, and/or (iii) averages of values derived from one or more of the DC output voltage signals and the linearity adjusted signals. The controller46may estimate the peak voltage of the RF voltage signal received at202based on one or more of the DC output voltage signals and/or the linearity adjusted signals. The representative value may be set equal to the estimated peak voltage.

If the first channel104is activated, the first channel104may be referred to as a primary channel and the second and/or third channels106,152may be referred to as secondary channels. If the first channel104is deactivated, the second channel106may be referred to as a primary channel and the third channel152may be referred to as a secondary channel. The representative value may be solely or primarily based on the first DC output voltage signal (or the first linearity adjusted signal) while the first channel104is activated. The representative value may be solely or primarily based on the second DC output voltage signal (or the second linearity adjusted signal) while the first channel104is deactivated. When determining the representative value, the DC output voltage signal (or the linearity adjusted signal) of the primary channel may be weighted more heavily than the one or more DC output voltage signals (or the linearity adjusted signals) of the one or more secondary channels.

At222, a system operator and/or the controller46may compare the representative value to a predetermined value. The predetermined value may be a predetermined voltage. For example, if the representative value is in a range of one of the DC output voltage signals or is in a range of one or more of the linearity adjusted signals, the predetermined value may be 10 (corresponding to 10V). As another example, if the representative value is in a range of the RF voltage signal received by the pickup device, the predetermined value may be 1000 (corresponding to 1000V). If the representative value is less than or equal to the predetermined value task224is performed, otherwise task226is performed.

At224, the first channel104, if not already activated, is activated. This may include the system operator manually or the controller46(i) increasing voltage of and/or applying a DC voltage to the anode of the diode D1, and (ii) decreasing voltage of and/or shutting off a DC voltage applied to the second anode of the diode D2, as described above. At226, the first channel104, if not already deactivated, is deactivated. This may include (i) the system operator manually or the controller46reducing voltage of and/or shutting off a DC voltage applied to the anode of the diode D1, and (ii) increasing and/or applying a DC voltage to the anode of the diode D2, as described above. Task202may be performed subsequent tasks224and226.

The above-described tasks are meant to be illustrative examples; the tasks may be performed sequentially, synchronously, simultaneously, continuously, during overlapping time periods or in a different order depending upon the application. Also, any of the tasks may not be performed or skipped depending on the implementation and/or sequence of events.

The above-described implementations include voltage sensors, each of which having linear response for multiple operating voltage ranges. This allows the corresponding VCIs to provide accurate control of high-frequency bias voltages over a broad overall dynamic voltage range.

The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.” It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure.

The controller may include one or more interface circuits. In some examples, the interface circuits may include wired or wireless interfaces that are connected to a local area network (LAN), the Internet, a wide area network (WAN), or combinations thereof. The functionality of any given controller of the present disclosure may be distributed among multiple controllers that are connected via interface circuits. For example, multiple controllers may allow load balancing. In a further example, a server (also known as remote, or cloud) controller may accomplish some functionality on behalf of a client controller.

The term memory circuit is a subset of the term computer-readable medium. The term computer-readable medium, as used herein, does not encompass transitory electrical or electromagnetic signals propagating through a medium (such as on a carrier wave); the term computer-readable medium may therefore be considered tangible and non-transitory. Non-limiting examples of a non-transitory, tangible computer-readable medium include nonvolatile memory circuits (such as a flash memory circuit or a mask read-only memory circuit), volatile memory circuits (such as a static random access memory circuit and a dynamic random access memory circuit), and secondary storage, such as magnetic storage (such as magnetic tape or hard disk drive) and optical storage.

The apparatuses and methods described in this application may be partially or fully implemented by a special purpose computer created by configuring a general purpose computer to execute one or more particular functions embodied in computer programs. The computer programs include processor-executable instructions that are stored on at least one non-transitory, tangible computer-readable medium. The computer programs may also include or rely on stored data. The computer programs may include a basic input/output system (BIOS) that interacts with hardware of the special purpose computer, device drivers that interact with particular devices of the special purpose computer, one or more operating systems, user applications, background services and applications, etc. The computer programs may include: (i) assembly code; (ii) object code generated from source code by a compiler; (iii) source code for execution by an interpreter; (iv) source code for compilation and execution by a just-in-time compiler, (v) descriptive text for parsing, such as HTML (hypertext markup language) or XML (extensible markup language), etc. As examples only, source code may be written in C, C++, C#, Objective-C, Haskell, Go, SQL, Lisp, Java®, ASP, Perl, Javascript®, HTML5, Ada, ASP (active server pages), Perl, Scala, Erlang, Ruby, Flash®, Visual Basic®, Lua, or Python®.