WO2021157750A1 - Capacitance-type state measuring device using sensor-mounted wafer - Google Patents

Abstract

The present invention relates to a state measuring device for monitoring a semiconductor process and, in particular, to a state measuring device which has, on a sensor-mounted wafer, metal electrodes for forming a capacitance so as to measure, using a capacitive method, a state of plasma or gas in a chamber. The state measuring device comprises: a first metal electrode disposed on the bottom surface of a first trench formed in a wafer; a second metal electrode disposed on the bottom surface of a second trench formed in the wafer; a third metal electrode disposed on both the bottom surface of the first trench and the bottom surface of the second trench so as to be spaced apart from the first metal electrode at a predetermined distance and spaced apart from the second metal electrode at a predetermined distance; a signal generator which generates and applies an excitation signal of a reference frequency to the third metal electrode; a mux which serially outputs discharge signals outputted in parallel from the first metal electrode and the second metal electrode; a conversion unit which converts the discharge signal for each metal electrode outputted from the mux into a digital signal; and a control unit which calculates a first capacitance value induced between the first metal electrode and the third metal electrode by using the digital signal, calculates a second capacitance value induced between the second metal electrode and the third metal electrode by using the digital signal, and calculates a change in the first capacitance value and a change in the second capacitance value.

Description

Capacitive state measuring device using sensor-mounted wafer

The present invention relates to a state measuring device for monitoring a semiconductor process, and in particular, a state measuring device for measuring the state of plasma or gas in a chamber in a capacitive manner by providing a metal electrode for forming capacitance on a sensor-mounted wafer is about

The semiconductor device manufacturing process includes an ion implantation process, a growth and deposition process, an exposure process, an etching process, and the like. During these processes, it is very important to monitor the state inside the chamber. Accordingly, a technique for monitoring the condition inside the chamber is continuously being studied.

In particular, in recent years, plasma equipment has been widely used in the process of depositing or etching a material film by forming plasma in a vacuum chamber and injecting a reaction gas. And there is a lot of demand to accurately measure the optimal performance under which circumstances.

The Langmuir probe is the most common technique for measuring the electron density or ion density of plasma used in a semiconductor manufacturing process.

The Langmuir probe inserts a probe into the chamber from the outside and measures the plasma characteristics by varying the power (voltage) applied to the probe. On the contrary, when a positive potential is applied to the probe, the electrons in the plasma are collected by the probe, and a current is generated by the electrons. At this time, after measuring the current generated by ions or electrons, the plasma density could be measured by analyzing the correlation with the voltage applied to the probe.

Since such a conventional Langmuir probe measures the density of plasma by inserting a probe into the chamber, it has the advantage of being able to measure the density of plasma in real time during the process. However, since the probe must be inserted into the chamber for measurement, there may be a problem in that the probe is contaminated by the deposition material during the deposition process. In addition, during the etching process, there was a problem that the probe was etched and abraded. As a result, it is difficult to apply it to the actual mass production process.

In addition, plasma oscillation probes and plasma absorption probes have been developed as tools for measuring plasma characteristics, but plasma oscillation probes have limitations in that they can only be measured under operating conditions that can withstand a hot wire at high pressure. There were disadvantages in that it was cumbersome to go through a calibration process and involved a complicated calculation process. After all, this improved technology also had a problem in that the effectiveness was lowered.

Accordingly, in order to measure the plasma or gas state in the chamber more simply and more accurately without physical loss such as probe contamination or wear, a sensing technology that can directly measure the state in the chamber without exposing the probe to plasma or gas this is required As a technology that meets this requirement, there is a sensor on wafer (SOW) technology developed for temperature sensing.

Since the SOW sensor and circuit for sensing are built into the wafer, the SOW is loaded into the chamber to directly perform the desired sensing operation inside the chamber. However, in order for SOW to sense an object generated by applying high-frequency power such as plasma in addition to temperature, it is necessary to solve the problem that the internal sensor or circuit malfunctions or is damaged due to high-frequency components generated when high-frequency power is applied.

The object of the present invention was devised in consideration of the above points, and in particular, to form a capacitance in a metal electrode provided inside a sensor-mounted wafer, and to measure the capacitance value or its change according to the change in the physical amount of a specific material in the chamber. An object of the present invention is to provide a capacitive state measuring device using a sensor-mounted wafer that calculates and measures the state of plasma or gas in the chamber.

A capacitive state measuring apparatus using a sensor-mounted wafer according to the present invention for achieving the above object is characterized by comprising: a first metal electrode disposed on a bottom surface of a first trench formed in the wafer; a second metal electrode disposed on a bottom surface of a second trench formed in the wafer; a third metal electrode spaced apart from the first metal electrode by a predetermined distance and disposed in common on a bottom surface of the first trench and a bottom surface of the second trench to be spaced apart from the second metal electrode by a predetermined distance; a signal generator for generating and applying an excitation signal of a reference frequency to the third metal electrode; a mux for serially outputting discharge signals output in parallel from the first metal electrode and the second metal electrode; a converter for converting the discharge signal for each metal electrode output from the mux into a digital signal; And a first capacitance value induced between the first metal electrode and the third metal electrode is calculated using the digital signal, and the first capacitance value induced between the second metal electrode and the third metal electrode is calculated using the digital signal. and a control unit that calculates a second capacitance value and calculates a change in the first capacitance value and a change in the second capacitance value.

Preferably, a first capacitor commonly connected to the first metal electrode and the third metal electrode to adjust the first capacitance value, and the second metal electrode and the third metal electrode are commonly connected to the A second capacitor for adjusting the second capacitance value may be further included.

More preferably, the first capacitor may have a relatively large capacitance value compared to the first capacitance value, and the second capacitor may have a relatively large capacitance value compared to the second capacitance value.

More preferably, a third capacitor connected in series to the first metal electrode to adjust a range of a first capacitance value adjusted by the first capacitor to a range measurable by the control unit; A fourth capacitor connected in series to the electrode to adjust the range of the second capacitance value adjusted by the second capacitor to the range of the value measurable by the controller may be further included.

Preferably, the control unit may further include a communication unit for transmitting the first capacitance value, the second capacitance value, the change in the first capacitance value, and the change in the second capacitance value calculated by the control unit to the outside.

More preferably, the first metal electrode, the second metal electrode, the third metal electrode, the signal generator, the converter, the control unit, and the communication unit may be isolated inside the wafer.

Preferably, the controller may calculate a change in the discharge amount of the first and second capacitances according to a change in a physical amount of a specific material in the chamber in which the wafer is loaded.

More preferably, the controller may control the signal generator to adjust the reference frequency of the excitation signal according to the type of the material.

More preferably, the material may include plasma or gas supplied to the interior of the chamber.

According to the present invention, there is no physical loss such as contamination or abrasion of the metal electrode used as a probe because the entire circuit as well as the metal electrode is configured to be isolated from the wafer.

In addition, the change in the value of the capacitance formed by applying a signal to the metal electrode or its change, in particular, the change in the discharge amount, is calculated to measure the change in the physical quantity (plasma density change, gas density change, vacuum state change, etc.) in the chamber. can In addition, it is possible to calculate the capacitance value or change thereof in a plurality of regions of the sensor-mounted waiter and compare them for each region, so that it is possible to monitor the change in the physical amount of the material present in the chamber during the semiconductor process as well as the uniformity in the chamber. As a result, simpler and more accurate monitoring becomes possible.

In addition, by applying the entire configuration of the present invention to SOW (Sensor On Wafer) technology that can measure the state directly in the chamber, while isolating the inside of the sensor-mounted wafer, sensors or circuits vulnerable to high-frequency components are covered with a metal layer, It can solve the problem of malfunctioning or damage to internal sensors or circuits.

1 is a block diagram showing the configuration of a capacitive state measuring device using a sensor-mounted wafer according to an embodiment of the present invention;

2 is a cross-sectional view showing a shape in which a metal electrode is provided inside the sensor-mounted wafer in the capacitive state measuring device using the sensor-mounted wafer according to the present invention;

3 is a plan view showing a structure in which a plurality of metal electrodes are disposed on the sensor-mounted wafer in the capacitive type state measuring device using the sensor-mounted wafer according to the present invention;

4 is a diagram showing an example of a configuration in which an apparatus according to the present invention is mounted on a sensor-mounted wafer.

Other objects, features and advantages of the present invention will become apparent from the detailed description of the embodiments with reference to the accompanying drawings.

Hereinafter, the configuration and operation of an embodiment of the present invention will be described with reference to the accompanying drawings, and the configuration and operation of the present invention shown in the drawings and described by this will be described as at least one embodiment, and in this The technical idea of the present invention and its core configuration and operation are not limited by the above.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the capacitive type state measuring apparatus using the sensor-mounted wafer according to the present invention will be described in detail.

1 is a block diagram showing the configuration of a capacitive type state measuring apparatus using a sensor mounted wafer according to an embodiment of the present invention, and FIG. 2 is a capacitive type state measurement using a sensor mounted wafer according to the present invention. A cross-sectional view showing a shape in which a metal electrode is provided inside a sensor-mounted wafer in the device, and FIG. 3 is a capacitive state measuring device using a sensor-mounted wafer according to the present invention, in which a plurality of metal electrodes are disposed on the sensor-mounted wafer It is a plan view showing the structure, and FIG. 4 is a diagram showing a configuration example in which the device according to the present invention is mounted on a sensor-mounted wafer.

1 to 4 , the state measuring device according to the present invention is configured to include metal electrodes 30 , 31 , 32 , a signal generator 40 , a converter 50 , and a controller 60 . .

The metal electrodes 30 , 31 , and 32 are formed to be isolated inside the sensor-mounted wafer. For this purpose, the first wafer 10 and the second wafer 20 are bonded in a vacuum atmosphere so that the inside is outside. It is desirable to form a shielded state from For example, the sensor-mounted wafer may be shielded inside to form a vacuum state. The first wafer 10 or the second wafer 20 constituting the sensor-mounted wafer may be a silicon-based wafer or a ceramic-based wafer having good insulation, robustness, and thermal conductivity.

2 shows a structure in which the metal electrodes 30, 31, and 32 are disposed inside the sensor-mounted wafer.

The sensor-mounted wafer includes a first trench 11 and a second trench 12 forming a recess of a predetermined depth, and a first metal electrode 31 and a third metal electrode 30 ) is formed inside the first trench 11 , and the second metal electrode 32 and the third metal electrode 30 are formed inside the second trench 12 .

The first metal electrode 31 is disposed on the bottom of the first trench 11 formed in the sensor-mounted wafer, and the second metal electrode 32 is disposed on the bottom of the second trench 12 formed in the sensor-mounted wafer.

The third metal electrode 30 is disposed in common in the first trench 11 and the second trench 12 . The third metal electrode 30 is spaced apart from the first metal electrode 31 by a predetermined distance and is spaced apart from the second metal electrode 32 by a predetermined distance. To this end, the third metal electrode 30 is commonly disposed on the bottom surface of the first trench 11 and the bottom surface of the second trench 12 .

Accordingly, the first metal electrode 31 and the third metal electrode 30 form a pair, and the second metal electrode 32 and the third metal electrode 30 form a pair.

The metal electrodes 30 , 31 , and 32 may be formed on either the first wafer 10 or the second wafer 20 constituting the sensor-mounted wafer, and the first wafer 10 or the second wafer ( 20) are disposed to be spaced apart from each other by a predetermined distance from the bottom of the trenches 11 and 12 formed in any one of them.

Meanwhile, an insulating film (not shown) may be provided between the metal electrodes 30 , 31 , and 32 and the sensor-mounted wafer. In more detail, trenches 11 and 12 are first formed in the first wafer 10 corresponding to the upper wafer among wafers constituting the sensor-mounted wafer. After an insulating film (not shown) is formed on the bottom surface of the trenches 11 and 12 , the metal electrodes 30 , 31 , and 32 may be formed to be spaced apart from each other on the insulating film (not shown). Here, the insulating layer may be a silicon oxide layer (SiO ₂ ) or a silicon nitride layer (SiNx).

The first metal electrode 31 and the third metal electrode 30 are spaced apart by a predetermined distance from the first trench region 300 in which the first trench 11 is formed, and the second metal electrode 32 and the third metal electrode ( 30 is spaced apart by a predetermined distance from the second trench region 310 in which the second trench 12 is formed. Accordingly, when a signal is applied to the third metal electrode 30 , a first capacitance Cv1 is formed in the first trench region 300 and a second capacitance Cv2 is formed in the second trench region 310 . .

The device of the present invention measures the value of the first capacitance Cv1 formed between the first metal electrode 31 and the third metal electrode 30 and the change thereof, and also the second metal electrode 32 and the third metal electrode The state inside the chamber in which the sensor-mounted wafer is loaded is monitored by measuring the value of the second capacitance (Cv2) formed between (30) and its change.

In particular, in the apparatus of the present invention, the first metal electrode 31 and the third metal electrode ( 30) by measuring the first capacitance value and its change amount induced between the Monitor the condition inside the chamber.

Measuring the first and second capacitance values and their changes formed as the device of the present invention applies a signal to the third metal electrode 30 is induced between the first metal electrode 31 and the third metal electrode 30 . Calculating the discharge amount of the first capacitance and the change in the discharge amount, and also calculating the discharge amount and the change in the discharge amount of the second capacitance induced between the second metal electrode 32 and the third metal electrode 30 same as

The signal generator 40 is configured to form capacitance in the first and second trench regions 300 and 310 , respectively, and generates and applies an excitation signal of a reference frequency to the third metal electrode 30 . In particular, the signal generator 40 adjusts the reference frequency of the applied excitation signal according to the type of material to be monitored. That is, the signal generator 40 applies excitation signals of different frequencies to the third metal electrode 30 according to the type of material to be monitored. The control unit 60 controls to adjust the reference frequency of the excitation signal according to the type of material to be monitored, so that the signal generating unit 40 transmits the excitation signal of a different frequency according to the type of material to the third metal electrode 30 . control to apply. The control unit 60 adjusts the reference frequency to an optimal frequency to which the plasma or a specific gas reacts.

Accordingly, the control unit 60 adjusts the reference frequency of the signal generation unit 40 according to which process is used when the sensor-mounted wafer 100 is loaded into the chamber, and accordingly the signal generation unit 40 controls the control unit. (60) generates an excitation signal of the adjusted frequency. Meanwhile, the excitation signal may be an AC waveform such as a sine wave, a square wave, or a triangular wave, and the signal generator 40 may be implemented as a Field Programmable Gate Array (FPGA) or a Complex Programmable Logic Device (CPLD).

The converter 50 converts the discharge signals output from the first and second metal electrodes 31 and 32 into digital signals. The converter 50 converts the discharge signal into a digital signal of a predetermined bit string.

On the other hand, as the pair of the first metal electrode 31 and the third metal electrode 30 and the pair of the second metal electrode 32 and the third metal electrode 30 are disposed on the sensor-mounted wafer, the mux 80 ) is provided at the input end of the converter 50 .

As the discharge signals output from the metal electrode pairs provided in the first and second trench regions 300 and 310 are output in parallel, the mux 80 converts the discharge signal for each metal electrode into a serial signal and outputs it to the converter 50 . do. That is, the mux 80 serially outputs discharge signals output in parallel from the first metal electrode 31 and the second metal electrode 32 .

The converter 50 converts the discharge signal for each metal electrode output from the mux 80 into a digital signal.

The control unit 60 calculates the value of the first capacitance Cv1 induced between the first metal electrode 31 and the third metal electrode 30 and the amount of change thereof using the digital signal output from the conversion unit 50 , and Also, the value of the second capacitance Cv2 induced between the second metal electrode 32 and the third metal electrode 30 and the amount of change thereof are calculated. The digital signal used to calculate the first capacitance (Cv1) value and its change amount and the digital signal used to calculate the second capacitance (Cv2) value and its change amount are serially output signals at different timings.

Since the controller 60 uses the discharge information converted into a digital signal, the induced between the first metal electrode 31 and the third metal electrode 30 as the physical amount of a specific material changes in the chamber in which the sensor-mounted wafer is loaded. The discharge amount of the first capacitance and the change in the discharge amount can be calculated, and the discharge amount of the second capacitance induced between the second metal electrode 32 and the third metal electrode 30 and the change in the discharge amount can be calculated.

The converter 50 and the controller 60 may be connected to each other by a Serial Peripheral Interconnect (SPI) bus or an Inter-Integrated Circuit (I2C) bus.

In particular, the control unit 60 calculates a change in the discharge amount of the first and second capacitances formed between the metal electrodes as the physical amount of a specific material changes in the space (inside the chamber) in which the sensor-mounted wafer 100 is loaded, respectively. Here, the material may include plasma or gas supplied to the space (inside the chamber).

Meanwhile, when calculating the first and second capacitance values induced between the metal electrodes and the amount of change thereof, respectively, for adjusting the first and second capacitance values and adjusting the measurement range of the first and second capacitance values configuration is required. This is because a negative capacitance value may be calculated due to causes such as temperature or dielectric constant, and a capacitance in a range that cannot be calculated by the controller 60 may be induced depending on the material in the chamber.

The device of the present invention further includes a first capacitor (Cd1) and a third capacitor (Cr1) for adjusting the value of the first capacitance (Cv1) induced between the first metal electrode (31) and the third metal electrode (30) and a second capacitor (Cd2) and a fourth capacitor (Cr2) for adjusting the value of the second capacitance (Cv2) induced between the second metal electrode (32) and the third metal electrode (30) .

The first capacitor Cd1 is commonly connected to the first metal electrode 31 and the third metal electrode 30 so that a first capacitance induced between the first metal electrode 31 and the third metal electrode 30 ( Cv1) Adjust the value. In particular, the first capacitor Cd1 is formed on the first metal electrode 31 so that the value of the first capacitance Cv1 induced between the first metal electrode 31 and the third metal electrode 30 is not calculated as a negative value. It may have a relatively large capacitance value compared to the first capacitance value induced between the and the third metal electrode 30 .

The second capacitor Cd2 is commonly connected to the second metal electrode 32 and the third metal electrode 30 so that a second capacitance induced between the second metal electrode 32 and the third metal electrode 30 ( Cv2) Adjust the value. In particular, the second capacitor Cd2 is formed by the second metal electrode 32 so that the value of the second capacitance Cv2 induced between the second metal electrode 32 and the third metal electrode 30 is not calculated as a negative value. It may have a relatively large capacitance value compared to the second capacitance value induced between the and the third metal electrode 30 .

Accordingly, the controller 60 may calculate the capacitance value adjusted by the first and second capacitors Cd1 and Cd2 and also calculate a change in the adjusted capacitance value.

The third capacitor Cr1 is connected in series to the first metal electrode 31 at the rear end of the first capacitor Cd1 to control the range of the first capacitance value adjusted by the first capacitor Cd1 by the controller 60 Adjust to the range of measurable values.

The fourth capacitor Cr2 is connected in series to the second metal electrode 32 at the rear end of the second capacitor Cd2 to control the range of the second capacitance value adjusted by the second capacitor Cd2 by the controller 60 Adjust to the range of measurable values.

The control unit 60 controls a first capacitance value induced between the first metal electrode 31 and the third metal electrode 30 or a second capacitance induced between the second metal electrode 32 and the third metal electrode 30 . If the capacity value is a fairly large value, it may not be possible to calculate it. The third and fourth capacitors Cr1 and Cr2 allow the controller 60 to calculate respective capacitances regardless of the magnitude of the induced first and second capacitance values.

As such, as the control unit 60 calculates the capacitance value and the amount of change thereof, it is possible to detect a change in the physical amount of the material present in the chamber, and compare the capacitance value in each trench region or compare the change amount of the capacitance in the chamber. The uniformity of the substances present in it can also be detected.

The device of the present invention further includes a communication unit 70 for transmitting the result calculated by the control unit 60, that is, the capacitance value calculated by the control unit 60 and the change in the capacitance value, to the outside in conjunction with the control unit 60 can do.

In the case of plasma, an electric field is formed in the chamber as a high-frequency power for forming plasma is applied. By measuring a change in the electric field, a change in the state of the plasma can be measured. For example, an electric field of a certain level is formed in the chamber by the high-frequency power, and in this state, the capacitance induced in the different trench regions 300 and 310 by the signal applied to the third metal electrode 30 is uniform. Charging and discharging can be repeated at high speed. However, if an electric field changes in the chamber for some reason, the discharge rate (discharge amount) of the capacitance induced in each trench region 300 and 310 may change, and the rate (discharge amount) at each trench region 300 and 310 is different. may be discharged with By calculating the change in the discharge rate (discharge amount) according to the change of the electric field, it is possible to detect the uniformity by comparing the discharge rate (discharge amount) as well as the plasma state change in the chamber.

Meanwhile, all elements constituting the device of the present invention, that is, the first metal electrode 31 , the second metal electrode 32 , the third metal electrode 30 , the first capacitor Cd1 and the second capacitor Cd2 ), the third capacitor (Cr1), the fourth capacitor (Cr2), the signal generating unit 40, the mux 80, the converting unit 50, the control unit 60, and the communication unit 60 are inside the sensor-mounted wafer. Isolation is preferred.

In addition, in the device of the present invention, in order to prevent the high-frequency component generated by the application of high-frequency power for plasma formation from adversely affecting the internal circuit, the high-frequency component is included in the region except for the trench regions 300 and 310 where the metal electrode pair is formed. A metal layer 15 to block the inflow may be further provided.

In more detail, except for the end of the first metal electrode 31 and the one end of the third metal electrode 30 that are opposed to each other, the end of the second metal electrode 32 and the third metal electrode 30 that face each other ), the signal generating unit 40, the converting unit 50, the control unit 60, and the communication unit 70 may be covered with the metal layer 15 formed on the sensor-mounted wafer.

The metal layer 15 blocking the inflow of high-frequency components may be formed on at least one of the upper surface and the lower surface of the first wafer 10 . For example, the metal layer may be formed only on the lower surface of the first wafer 10 , , a metal layer may be formed only on the upper surface of the first wafer 10 . On the other hand, when the metal layer is formed only on the upper surface of the first wafer 10 , it is preferable to form a protective film (not shown) for protecting the metal layer on the entire surface of the first wafer 10 . For example, the passivation layer may be an oxide layer. In addition, when the metal layer is formed on the lower surface of the first wafer 10 , the insulating layer 16 may be provided between the metal electrodes 30 , 31 , and 32 and the metal layer 15 .

The metal layer 15 that blocks the inflow of the high-frequency component is formed in the region except for the trench regions 300 and 310 in which the metal electrode pairs are formed, and is not formed entirely on the upper surface and/or the lower surface of the first wafer 10 . A first trench region 300 in which the first metal electrode 31 and the third metal electrode 30 are spaced apart, and a second trench region in which the second metal electrode 32 and the third metal electrode 30 are spaced apart In 310, it is preferable to have an open structure.

The apparatus of the present invention arranges a plurality of paired metal electrodes on the sensor-mounted wafer to monitor the uniformity as well as the change in the physical amount of the material present in the chamber during the semiconductor process.

The apparatus of the present invention can monitor process conditions such as plasma state change, plasma uniformity, gas state change, gas uniformity, vacuum state change, etc. by disposing a plurality of paired metal electrodes in a plurality of regions of the sensor-mounted wafer.

For example, in the case of monitoring plasma uniformity, a plurality of pairs of metal electrodes are provided in the trench regions 300 and 310 arranged at a uniform spacing as shown in FIG. 4 . The uniformity can be measured from whether an error occurs in the plasma state change measured in the metal electrode pairs formed in the trench regions 300 and 310 .

In the device according to the present invention, the metal electrode pair may be disposed in multiple regions of the sensor-mounted wafer 100 . The trench regions 300 and 310 are arranged in a plurality of regions to correspond to the arrangement of the metal electrode pair. The arrangement of the trench regions 300 and 310 in which the metal electrode pair is formed is preferably arranged to have a uniform separation distance.

Accordingly, the control unit 60 may calculate the capacitance induced by the metal electrode pair of the plurality of trench regions 300 and 310 and the change in the discharge amount thereof, respectively.

In addition, in the present invention, the device may include a battery for supplying power to the circuit, a wireless charging circuit for wireless charging of the battery, and a memory for storing the result calculated by the control unit.

Although preferred embodiments of the present invention have been described so far, those of ordinary skill in the art to which the present invention pertains will be able to implement it in a modified form without departing from the essential characteristics of the present invention.

Therefore, the embodiments of the present invention described herein should be considered from an illustrative rather than a limiting standpoint, and the scope of the present invention is indicated in the claims rather than in the above description, and all differences within the equivalent scope are the present invention. should be construed as being included in

The capacitive state measuring apparatus according to the present invention is variously used to measure the state of plasma or gas inside a chamber in a process of manufacturing a semiconductor device such as an ion implantation process, a growth and deposition process, an exposure process, and an etching process. can be applied.

Claims (9)

1. a first metal electrode disposed on a bottom surface of the first trench formed in the wafer;

   a second metal electrode disposed on a bottom surface of a second trench formed in the wafer;

   a third metal electrode spaced apart from the first metal electrode by a predetermined distance and disposed in common on a bottom surface of the first trench and a bottom surface of the second trench to be spaced apart from the second metal electrode by a predetermined distance;

   a signal generator for generating and applying an excitation signal of a reference frequency to the third metal electrode;

   a mux for serially outputting discharge signals output in parallel from the first metal electrode and the second metal electrode;

   a converter for converting the discharge signal for each metal electrode output from the mux into a digital signal; And

   A first capacitance value induced between the first metal electrode and the third metal electrode is calculated using the digital signal, and a first capacitance value induced between the second metal electrode and the third metal electrode is calculated using the digital signal. and a control unit for calculating two capacitance values and calculating a change in the first capacitance value and a change in the second capacitance value.

   A capacitive state measuring circuit for detecting a change in a physical quantity in a chamber by calculating a change in the first and second capacitance values.
2. The method of claim 1,

   a first capacitor commonly connected to the first metal electrode and the third metal electrode to adjust the first capacitance value;

   and a second capacitor commonly connected to the second metal electrode and the third metal electrode to adjust the second capacitance value.
3. 3. The method of claim 2,

   The first capacitor has a relatively large capacitance value compared to the first capacitance value, and the second capacitor has a relatively large capacitance value compared to the second capacitance value. measuring circuit.
4. 3. The method of claim 2,

   a third capacitor connected in series to the first metal electrode to adjust a range of a first capacitance value adjusted by the first capacitor to a range measurable by the control unit;

   and a fourth capacitor connected in series to the second metal electrode to adjust the range of the second capacitance adjusted by the second capacitor to the range of values measurable by the controller. The state measurement circuit of the scheme.
5. The method of claim 1,

   The capacitive method further comprising a communication unit for transmitting the first capacitance value, the second capacitance value, the change of the first capacitance value, and the change of the second capacitance value calculated by the control unit to the outside of the state measurement circuit.
6. 6. The method of claim 5,

   The first metal electrode, the second metal electrode, the third metal electrode, the signal generating unit, the converting unit, the control unit, and the communication unit are separated inside the wafer. .
7. The method of claim 1,

   The control unit is

   Capacitive state measurement circuit, characterized in that the change in the discharge amount of the first and second capacitance is calculated according to a change in a physical amount of a specific material in the chamber in which the wafer is loaded.
8. 8. The method of claim 7,

   The control unit is

   A capacitive state measuring circuit, characterized in that the signal generator is controlled to adjust a reference frequency of the excitation signal according to the type of the material.
9. 8. The method of claim 7,

   The material is a capacitive state measuring circuit, characterized in that it contains plasma or gas supplied to the inside of the chamber.

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