WO2023158227A1

WO2023158227A1 - Plasma process monitoring method, plasma process monitoring device, and plasma generation device

Info

Publication number: WO2023158227A1
Application number: PCT/KR2023/002230
Authority: WO
Inventors: 정진욱; 서범준
Original assignee: 한양대학교 산학협력단
Priority date: 2022-02-17
Filing date: 2023-02-15
Publication date: 2023-08-24
Also published as: KR20230123791A

Abstract

A plasma generation device according to one embodiment may comprise: a chamber in which plasma is generated; at least one sensor arranged inside the chamber; a voltage application unit for applying, to the sensors, three or more sinusoidal voltages having different frequencies; a measurement circuit unit for measuring output current flowing in the sensors; and a data processing unit for calculating the thickness of a dielectric inside the chamber on the basis of information about the sinusoidal voltages and information about the output currents.

Description

Plasma process monitoring method, plasma process monitoring device and plasma generating device

The present invention relates to a plasma process monitoring method, a plasma process monitoring device, and a plasma generating device, and more specifically, to a technique for measuring the thickness of a dielectric in real time by applying a plurality of multi-frequency sinusoidal voltages to plasma and a dielectric. It is an invention.

Plasma is an ionized gas, composed of positive ions, negative ions, electrons, excited atoms, molecules, and chemically very active radicals. Also called the fourth state. This plasma contains ionized gas and is very useful in semiconductor manufacturing processes such as accelerating it using an electric or magnetic field or causing a chemical reaction to clean, etch, or deposit a wafer or substrate.

Recently, plasma generators that generate high-density plasma are used in semiconductor manufacturing processes, and there are several plasma modules for generating plasma. Capacitive coupled plasma (CCP) using radio frequency and inductively coupled plasma (ICP) are representative examples.

When performing a plasma deposition process using such a plasma device, it is necessary to monitor the inside of the plasma chamber and accurately check plasma conditions (plasma density, electron temperature, etc.) and dielectric conditions. Because, if the organic or inorganic material (dielectric layer, hereinafter referred to as dielectric) deposited on the wall of the chamber where the plasma is formed falls off again and impurity particles are formed, there is a concern that the product yield may decrease, and the plasma may be in an undesirable state. This is because there is a possibility that the deposition environment may be changed due to change.

As a method for diagnosing plasma, the Langmuir probe method is widely used. The Langmuir probe method measures various process parameters such as electron temperature and plasma density from information on the current measured by the probe by inserting a probe into the plasma chamber and applying a voltage.

After the semiconductor process is performed, metrology is performed to analyze the internal state of the chamber and the characteristics of the device. When the measurement is performed, the deposition state and the wear degree of the dielectric can be measured in various ways. Contact-type surface step difference measurement method (alpha step), which measures the thickness by measuring the position change of the probe while scratching the surface after making a step on the dielectric-coated sample, and cutting the dielectric-coated sample Scanning electron microscopy (SEM) method, which measures thickness through the intensity of secondary electrons emitted by scanning electron beams, and ellipsometer method, which measures thickness from changes in the polarization state of reflected light after reflecting light on a dielectric sample However, these measurement methods have disadvantages in that it is difficult to directly measure the thickness of the chamber wall deposition film or the edge ring during the process, and it is difficult to measure the thick dielectric. In addition, in the case of a thin deposited film, although it can be measured in an indirect way through sample production, real-time measurement is not possible, and professional knowledge is required for sample production and analysis, and there are disadvantages in that reliability is determined by the user's proficiency.

Therefore, a plasma process monitoring device, a plasma generating device, and a plasma process monitoring method according to an embodiment are inventions designed to solve the above-described problems, and can measure in real time while accurately measuring the thickness of a dielectric more effectively than the prior art Its purpose is to provide technology.

More specifically, after applying a plurality of multi-frequency sinusoidal voltages to the plasma and the dielectric, the impedance value is calculated based on the magnitude of the current generated and the applied voltage, etc., and the thickness of the dielectric is based on the calculated impedance value. An object of the present invention is to provide a plasma process monitoring device, a plasma generating device, and a plasma process monitoring method capable of more accurately monitoring a deposition process by measuring in real time.

A plasma generating device according to an embodiment includes a chamber in which plasma is generated, at least one sensor disposed inside the chamber, a voltage applicator for applying three or more voltages having different frequencies to the sensor, and an output current flowing through the sensor. It may include a measurement circuit unit for measuring and a data processing unit for calculating the thickness of the dielectric inside the chamber based on the information on the sine wave voltage and the information on the output current.

The data processor may calculate the thickness of the dielectric using an equivalent circuit model with a circuit configuration of a dielectric capacitor generated by depositing the dielectric, a sheath capacitor in a sheath region generated adjacent to the plasma, and a sheath resistance. .

The three or more voltages may include three or more sinusoidal voltages having different frequencies.

The three or more sinusoidal voltages may include a first sinusoidal wave, a second sinusoidal wave, and a third sinusoidal wave having different frequencies, and the voltage application unit simultaneously transmits the first sinusoidal wave, the second sinusoidal wave, and the third sinusoidal wave. It may be applied, or it may be applied with a time difference.

When the first sinusoidal wave, the second sinusoidal wave, and the third sinusoidal wave are applied, the data processing unit calculates the thickness of the dielectric based on the magnitude of current measured respectively and the impedance information of the equivalent circuit model. .

The data processing unit may recalculate the thickness of the dielectric based on information calculated in consideration of a fringing effect occurring in the dielectric.

The data processor may calculate the thickness of an edge ring in the chamber based on the information about the sine wave voltage and the information about the output current.

The plasma generating device further includes a control unit that calculates a difference between the calculated thickness of the edge ring and a preset reference thickness, and then moves the edge ring upward by the difference when the difference is out of a preset range. can include

A plasma process monitoring apparatus according to an embodiment includes a voltage applicator for applying three or more sinusoidal voltages having different frequencies to at least one sensor disposed inside a chamber in which plasma is generated, and a voltage applicator for measuring an output current flowing through the sensor. It may include a measurement circuit and a data processing unit that calculates the thickness of the dielectric inside the chamber based on the information about the sine wave voltage and the information about the output current.

The three or more sinusoidal voltages include a first sinusoidal wave, a second sinusoidal wave, and a third sinusoidal wave having different frequencies, and the voltage application unit simultaneously applies the first sinusoidal wave, the second sinusoidal wave, and the third sinusoidal wave. Alternatively, it may be applied with a time difference.

The plasma process monitoring device further includes a control unit that calculates a difference between the calculated thickness of the edge ring and a preset reference thickness, and then moves the edge ring upward by the difference when the difference is out of a preset range. can include

A plasma process monitoring method according to an embodiment includes a voltage human step of applying three or more sinusoidal voltages having different frequencies to at least one sensor disposed inside a chamber in which plasma is generated, measuring an output current flowing through the sensor A current measuring step and a data processing step of calculating a thickness of a dielectric inside the chamber based on the information on the sine wave voltage and the information on the output current may be included.

The plasma process monitoring method, plasma process monitoring device, and plasma generating device according to an embodiment accurately calculate the thickness of the actually deposited dielectric without being affected by the discharge conditions, unlike the prior art, even if the discharge conditions applied to the chamber are changed. And there is an advantage in that the thickness of the dielectric can be monitored in real time even when the dielectric is being generated during the actual deposition process.

In addition, since the present invention measures the thickness of the dielectric based on the measured impedance value rather than the phase difference of the current, it is possible to measure the thickness more precisely than in the prior art, and further apply the frequency of the MHz band as well as the kHz band frequency However, there is an advantage in that the thickness of the dielectric can be accurately measured.

In addition, since the present invention can also measure the thickness of the edge ring installed for the uniformity of the plasma generated inside the chamber in real time, when it is determined that the wear of the edge ring has progressed a lot, the edge ring is moved upward to reduce the plasma There is an advantage of maintaining uniformity.

The effects of the present invention are not limited to the technical problems mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

In order to more fully understand the drawings cited in the detailed description of the present invention, a brief description of each drawing is provided.

1 is a circuit diagram modeling between a plasma and a probe when a voltage is applied to the probe according to the prior art.

2 is a perspective view of a plasma generating device according to an embodiment of the present invention when viewed from the side.

3 is a block diagram showing some components of a plasma process monitoring apparatus according to an embodiment of the present invention.

4 is a flowchart illustrating a method for monitoring a plasma generating process according to an embodiment of the present invention.

5 is a diagram showing the inside of a chamber as an equivalent circuit according to an embodiment of the present invention.

6 is a diagram showing experimental results when the thickness of a dielectric is measured in consideration of a fringing effect according to an embodiment of the present invention.

7 is a diagram showing actual experimental results when the thickness of a dielectric is measured using an equivalent circuit model according to an embodiment of the present invention.

8 is a diagram showing experimental results when the thickness of a dielectric is measured by applying the plasma process monitoring method according to the present invention to a plasma chamber.

9 is a diagram showing experimental results when the thickness of a dielectric is measured by applying the plasma process monitoring method according to the present invention to a display process chamber.

10 is a diagram for explaining an edge ring compensation method according to an embodiment of the present invention.

Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings. In adding reference numerals to the components of each drawing, it should be noted that the same components have the same numerals as much as possible even if they are displayed on different drawings. In addition, in describing an embodiment of the present invention, if it is determined that a detailed description of a related known configuration or function hinders understanding of the embodiment of the present invention, the detailed description thereof will be omitted. In addition, embodiments of the present invention will be described below, but the technical idea of the present invention is not limited or limited thereto and can be modified and implemented in various ways by those skilled in the art.

In addition, terms used in this specification are used to describe embodiments, and are not intended to limit and/or limit the disclosed invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

In this specification, terms such as "include", "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or the existence or addition of more other features, numbers, steps, operations, components, parts, or combinations thereof is not excluded in advance.

In addition, throughout the specification, when a part is said to be “connected” to another part, this is not only the case where it is “directly connected”, but also the case where it is “indirectly connected” with another element in the middle. Terms including ordinal numbers, such as "first" and "second" used herein, may be used to describe various components, but the components are not limited by the terms.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted.

When a voltage is applied to a probe existing inside the plasma chamber, a sheath region is generally generated between the probe and the plasma.

The sheath area refers to a space in which quasi-neutrality is broken. Specifically, it refers to a dark space area where plasma does not emit light in the process of generating plasma within the chamber space. It happens.

In general, since plasma exists in an ionized gaseous state in which atoms or molecules are separated into positive ions and free electrons, free electrons freely move inside the chamber and combine with positive ions to emit light. However, in the vicinity of the surface of the probe or the wall of the chamber, it is negatively charged due to the free electrons arriving at the wall before the positive ions, and since the free electrons approaching the wall are pushed away by the repulsive force, only positive ions and neutrons remain mainly around the surface of the probe or the wall. As a result, a dark space is generated in which free electrons cannot combine with positive ions. And these areas are called sheath areas.

In addition, a region in which the deposited organic or inorganic material falls off and impurity particles are formed is generated on the wall surface of the chamber where the plasma is formed, and the thus formed impurities form a dielectric material.

Therefore, this region can be implemented as an equivalent circuit. Specifically, as shown in FIG. 1, the sheath region located on the surface of the probe can be considered as a resistance component. When an AC voltage is applied to the floating potential probe, the corresponding voltage is applied to the plasma sheath, the dielectric is approximated as one capacitor (Cd, capacitor), and the sheath region is approximated as sheath resistance (Rs, sheath resistance). Since an equivalent model circuit can be implemented as shown in , the thickness of the dielectric can be measured by analyzing it.

However, when the thickness of the dielectric is measured by the method shown in FIG. 1, when the discharge conditions such as applied power applied to the plasma are changed, the error between the thickness of the dielectric calculated from the conventional circuit model and the thickness of the actually deposited dielectric becomes There are problems that arise. Therefore, there is an urgent need to develop a technology capable of more accurately monitoring a deposition process by accurately calculating a dielectric thickness even when a plasma state is changed due to a change in plasma discharge conditions.

Therefore, a plasma process monitoring device, a plasma generating device, and a plasma process monitoring method according to an embodiment are inventions designed to solve the above-described problems, and can measure in real time while accurately measuring the thickness of a dielectric more effectively than the prior art Its purpose is to provide technology. The configuration and operating principle of the present invention will be described in detail through the following drawings.

Referring to FIG. 2, the plasma generating device 1 according to the present invention includes a first sensor 20A, a second sensor 20B, and a first sensor ( 20A) and a voltage applying unit 30 for applying a preset voltage to the first sensor 20A, a chamber 40 serving as a main body of the plasma generating device 1 and a space in which plasma is generated, and a plasma generating device 100 ) The power module 50 for supplying power, the impedance matching unit 70 for matching the impedance of the antenna 60, and the current flowing through the first sensor 20A and the second sensor 20B are measured, and the measured It may include a plasma process monitoring device 100 that calculates various parameters of plasma based on the resulting values.

Referring to FIG. 2 , the chamber 40 may refer to a container having a space in which an object to be processed requiring plasma processing, such as a substrate, is provided and a space in which plasma P is generated. As shown in FIG. 2, a plurality of antennas 60 for generating plasma may be installed in the upper portion of the chamber 40, and the plurality of antennas 60 may be connected to an impedance matching unit 70 (matching box). there is. The impedance matching unit 70 may be connected to the power module 50 and the chamber 40 respectively, which supply power to the plasma generating device 100, and although not shown in the figure, a plasma generating source is located in the lower part of the chamber 40. A pumping system for pumping a source gas or the like to become a source gas may be formed.

As shown in FIG. 2 , a plasma generating device generating plasma using a plurality of antennas 60 may be referred to as an inductively coupled plasma generating device. However, the plasma generating device according to the present invention is not limited to an inductively coupled plasma generating device, and may be applied to both devices and methods for generating plasma using a capacitive coupling method. For convenience of description, the description will be made based on the inductively coupled plasma generating device shown in FIG. 2 .

The plasma process monitoring apparatus 100 according to an embodiment of the present invention may measure various variables of plasma generated inside the chamber 40 . The variable referred to in the present invention refers to a variable that means various chemical and physical characteristics related to plasma, and is representative of the density of plasma generated inside the chamber 40, the temperature of electrons flowing inside the chamber and the probability distribution of electron energy, The thickness of the dielectric 10 formed on the wall of the chamber may be measured.

To this end, a plurality of sensors may be provided inside the chamber 40. As a representative embodiment, a first sensor 20A and a second sensor 20B capable of transmitting a sinusoidal wave to plasma may be provided. As shown in the drawing, the first sensor 20A and the second sensor 20B may be disposed to pass through one wall of the chamber 40 . As an example, as shown in the drawing, when the first sensor 20A and the second sensor 20B pass through the chamber 40 and apply a sine wave signal to the plasma, the first sensor 20A and the first sensor ( 20B) can be said to have the form of a floating probe.

After generating a voltage, the voltage application unit 30 may apply the generated voltage to the first sensor 20A and the second sensor 20B. As shown in FIG. 2 , the voltage application unit 30 is electrically connected to the first sensor 20A and the second sensor 20B, and the user's A preset voltage according to settings may be applied. The shape and size of the voltage applied to the first sensor 20A and the second sensor 20B by the voltage application unit 30 may be set differently according to the plasma generating environment, but in the form of a sine wave generated by an AC voltage. A plurality of voltages may be applied. For example, the voltage applicator 30 may apply three sine wave voltages having different frequencies w1 , w2 , and w3 to the sensor 20 .

As shown in FIG. 2 , the first sensor 20A and the second sensor 20B are disposed inside the chamber 40 and may be configured as probes made of metal to allow current to flow.

When voltage is applied to the first sensor 20A and the second sensor 20B by the voltage application unit 30, the first sensor 20A and the second sensor 20B due to a potential difference between the plasma and the first sensor 20A and the second sensor 20B. Since current flows through the first sensor 20A and the second sensor 20B, the plasma process monitoring apparatus 100 can measure the current flowing through the first sensor 20A and the second sensor 20B. The arrangement of the plasma process monitoring device 100 in FIG. 2 is not limited thereto, and in another embodiment, the plasma process monitoring device 100 may be disposed between the first sensor 20A and the voltage applying unit 30. .

Meanwhile, in the drawing, the voltage applicator 30 and the plasma process monitoring device 100 are shown as independent and separate components, but the embodiment of the present invention is not limited thereto, and the voltage applicator 30 is the plasma process monitoring device 100. ) may be implemented as being included in.

Referring to FIG. 3, the plasma process monitoring apparatus 1 includes a sensor 20 installed on one side of a plasma chamber 40, a measuring circuit unit 110 for measuring an output current of the sensor 20, and at least three After applying AC voltages having different frequencies, the data processing unit 120 calculates the thickness of the dielectric 10 deposited inside the chamber 40 based on the measured data, and the data processing unit 120 calculates the output current It may include an interface unit 130 that transmits data to the data processing unit 120 and a display unit 140 that displays monitoring information calculated from the data processing unit 120 .

The data processing unit 120 (microcontroller unit) may apply an AC voltage to the sensor 20 while measuring and processing an output current from the sensor 20 . To this end, the data processing unit 120 calculates the thickness of the dielectric 10 from the control unit 121 that calculates the thickness of the dielectric 10 by receiving the output current obtained from the measuring circuit unit 110, and the actual output current. It may include a calculation unit 122 and an external communication unit 123 for transmitting and receiving calculated monitoring information to and from an external device.

The control unit 121 oscillates AC voltages having at least three different frequencies, commands the measurement circuit unit 110 to measure the output current, and monitors the plasma process by outputting or receiving the thickness of the dielectric 10 to the outside. It is possible to control the overall device (1). A digital-to-analog converter 124 may be disposed adjacent to the controller 121 .

The calculation unit 122 receives the output current of the measurement circuit unit 110 and calculates thickness information of the dielectric 10 of the sensor 20 from the magnitude and phase difference of the output current. In this embodiment, the aforementioned sheath resistance (Rs), the sheath capacitor (Cs), and the thickness of the dielectric 10 calculated therefrom are calculated. In addition, the external communication unit 123 transmits and receives the calculated monitoring information to and from external devices, mainly the computer 150 and the like. The external communication unit 123 may be a wireless or wired communication means.

While conventional plasma process monitoring devices must necessarily include a computer connected to the process monitoring device, in this embodiment, the process monitoring device 100 includes a data processing unit 120 that performs calculations and analyzes, There is an advantage that the computer performing the analysis and the analysis can be omitted.

Meanwhile, the data processing unit 120 may be manufactured in the form of a single chip or may be manufactured in the form of a single board, the plasma process monitoring device 100, including the measurement circuit unit 110 and the interface unit 130 to be described later. Accordingly, the data processing unit 120 may be a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA), a programmable logic unit (PLU), a microprocessor, or instructions. It can be implemented as a device that can execute and respond to (instruction).

The measurement circuit unit 110 is disposed between the data processing unit 120 and the sensor 20 and amplifies the alternating voltage oscillated by the data processing unit 120 through an op-amp 111 to obtain a sensor 20 , and the output current flowing through the sensor 20 can be sensed. The output current is output to the analog-digital converter 141 (ADC) via the current measuring unit 112 having the measuring resistor 113 and the differential amplifier 114. Meanwhile, in the present embodiment, it has been described above that only the output current is measured by the measuring circuit unit 110 to calculate the thickness information of the dielectric 10, but the output voltage through which the probe is energized may also be used.

The analog-to-digital converter 141 is provided adjacent to the measurement circuit unit 110 and can convert an analog signal into a digital signal and output it to the data processing unit 120 through the interface unit 130 .

The display unit 140 displays the monitoring information calculated by the data processing unit 120 to the operator. The operator calculates the thickness of the dielectric 10 calculated from the data processing unit 120 through the display unit 140, specifically, in this embodiment, the output current measured from the measuring circuit unit 110 and the calculated through the data processing unit 120. The thickness of the dielectric 10 can be easily monitored.

The plasma process monitoring device including the data processing unit 120, the measurement circuit unit 110, the analog-to-digital converter 141, the measurement circuit unit 140, and the interface unit 130 is detachably installed on one side of the chamber 40. It can be.

The plasma process monitoring apparatus 100 having such a configuration can realize a smaller size than the conventional one. That is, the conventional plasma process monitoring device must be separately provided with an external device such as a computer to calculate and analyze output data, and a data acquisition board (DAQ) to connect to the computer. In particular, since the size of the DAQ is large, there is a problem in miniaturizing the process monitoring device.

However, in the case of the plasma process monitoring device 100 according to the present invention, the data processing unit 120 receives an output signal such as an output current, calculates and analyzes it by itself, so that the computer 150 is not necessarily required, DAQ can be omitted, resulting in miniaturization. Instead of DAQ being omitted, connection with an external device may be performed through wired or wireless communication through the external communication unit 123 . Since plasma can be monitored only with the miniaturized process monitoring device 100, it is easy to move and has advantages in terms of installation and maintenance.

On the other hand, as described in FIG. 1 above, according to the prior art, a sinusoidal alternating voltage of a single frequency is applied to measure the output current, and the sheath resistance (Rs) is derived from the information on the magnitude component of the measured first harmonic, and the dielectric When calculating the thickness of (10), when the discharge conditions applied to the chamber (eg, applied power, type and flow rate of gas, internal pressure, etc.) are changed, the calculated thickness of the dielectric 10 and the actually deposited dielectric There is a problem that the error between the thicknesses of (10) is severe, and the method of measuring the thickness of the dielectric 10 using the phase difference also causes a large error in the phase difference measurement as the deposition film becomes thicker, resulting in poor reliability. There is a problem of lowering, and furthermore, there is a problem of not being able to measure the thickness of the dielectric 10, such as the edge ring in mm, because the applied frequency is low.

Therefore, in the plasma process monitoring method according to an embodiment, in order to solve the above problem, three or more AC voltages (V(t)=cos(w*t)) having different frequencies are applied to the sensor 20 are applied simultaneously or individually, and then an equivalent circuit model is created using information on the current output for the applied voltage, and the thickness of the dielectric 10 is calculated based on this, so that the dielectric 10 is more accurate and real-time. thickness can be measured. Hereinafter, a plasma process monitoring method according to an embodiment of the present invention will be described with reference to the drawings. The plasma process monitoring method is a method of monitoring a plasma state inside the chamber 40 using the above-described plasma process monitoring apparatus 100 .

4 is a flowchart illustrating a method for monitoring a plasma generation process according to an embodiment of the present invention, and FIGS. 5A and 5B are diagrams showing the interior of a chamber as an equivalent circuit according to an embodiment of the present invention.

Referring to the flowchart shown in FIG. 4, the plasma process monitoring method according to the present invention includes the steps of applying a plurality of AC voltages having different frequencies to the sensor 20 (S110), and The step of measuring the output current (S120), the step of calculating the impedance of the equivalent circuit model based on the equivalent circuit model, the size of the current and the measured information (S130), and the thickness of the dielectric based on the calculated impedance value It may include a step of calculating, and a step of transmitting information on the calculated dielectric thickness to the outside (S150).

The step of applying a plurality of AC voltages to the sensor 20 ( S110 ) is a step of applying an AC voltage from the data processing unit 120 or the voltage application unit 30 of the plasma process monitoring apparatus 100 . For convenience of explanation, it is assumed that the voltage is applied from the data processing unit 120 .

The data processor 120 may simultaneously or sequentially apply a plurality of AC voltages having different frequencies to the sensor 20 . The applied AC voltage is energized to the sensor 20 via the op-amp 111 and the current measurement unit 112 of the measurement circuit unit 110. In this specification, for convenience of description, it is assumed that three sine waves having different frequencies (w1, w2, w3) are applied as AC voltages applied by the data processing unit 120, but the embodiment of the present invention is limited to this. It is not, and four or more sine waves may be applied.

Meanwhile, in FIG. 3, for convenience of description, the data processing unit 120 has been illustrated and described as applying a plurality of alternating voltages, but in another embodiment, the plasma process monitoring apparatus 100 has a voltage applying unit for applying a plurality of voltages to the data processing unit 120. It may be configured separately from the processing unit 120 .

In the step of measuring the output current generated by the sensor 20 (S120), the output current flowing through the sensor 20 is sensed through the measuring circuit unit 110.

The measurement circuit unit 110 includes a measurement resistor 113 and a differential amplifier 114 to amplify the fine output current and remove noise. Thereafter, the analog-to-digital converter 141 outputs the signal, and the output signal converted into a digital signal may be transferred to the data processing unit 120 through the interface unit 130.

In the step of calculating the impedance based on the equivalent circuit model and the measured information (S130), the equivalent circuit model is configured for the metal structure installed in the chamber as shown in FIG. 5, and based on this, the entire equivalent circuit model is calculated. This is the step of calculating the impedance.

Specifically, when a multi-frequency sinusoidal voltage is applied to the metal structure installed on the inner wall of the chamber 40, the inside of the plasma is represented by the sinusoidal signal generator 210, the dielectric 220, the sheath 230, and the plasma 240. 5, the dielectric 220 may be expressed as a dielectric capacitor Cdep, and the sheath 230 may be expressed as a sheath resistance Rsh and a sheath capacitor Csh. Meanwhile, the dielectric capacitor Cdep may be referred to as a first capacitor and the sheath capacitor Csh may be referred to as a second capacitor according to the designation names.

Meanwhile, in the equivalent circuit model shown in FIG. 5A, the sheath impedance (Zsh) for the sheath 230 may be defined by Equation (1) below according to the characteristics of the AC voltage.

Further, the dielectric impedance (Xdep) of the dielectric 220 and the total impedance (Ztotal) of the equivalent circuit model may be expressed as Equation (2) below.

On the other hand, when a plurality of sinusoidal voltages having different frequencies are applied, using the measured current (I) and using the V = I * R formula, the equation can be organized as Equation (3) below there is.

The step of calculating the thickness of the dielectric based on the calculated impedance value is a process of obtaining a value of the dielectric capacitor (Cdep) of the dielectric 220 using the above equations and calculating the thickness of the dielectric based on this.

By solving the equation based on Equation (1), Equation (2) and Equation (3), the value of the dielectric capacitor can be calculated. ) and the reactance of the dielectric (Xdep,wn) change, if this is used, Equation (3) and equation are generated, converted into a matrix, and then the matrix is solved using the measured current value and voltage value, etc. Impedance (Xdep,wn) can be calculated.

And, when the dielectric impedance (Xdep) is calculated, based on this, the capacitance (Cdep) of the dielectric can be known as in Equation (4) below, and finally, if the area (A) of the metal structure and the permittivity ε of the dielectric 220 are known, The thickness d of the dielectric may be measured as shown in Equation (5) below, and all of the steps (S230) of calculating the thickness of the dielectric may be performed by the calculation unit 122.

In addition, when the conductivity of the dielectric is high as shown in FIG. 5B, after obtaining an equivalent circuit model by adding parallel resistance to the dielectric equivalent circuit, the thickness of the dielectric can be measured through the method described above.

The step of outputting the thickness of the dielectric to the outside (S240) is a step of displaying the thickness of the dielectric to the user through the display unit 140, in this case, an external computer using the external communication unit 123 in the data processing unit 120. (150) and the like can be communicated.

As described above, according to the plasma process monitoring apparatus 100 and the plasma process monitoring method according to the present embodiment, the discharge conditions applied to the chamber 40 (eg, applied power, gas type and flow rate, internal pressure, etc.) Even if it is changed, the thickness of the dielectric can be calculated relatively accurately to the thickness of the actually deposited dielectric. In addition, there is an advantage in that the thickness of the dielectric can be monitored in real time even when the dielectric is being generated while the actual deposition process is being performed.

In addition, since the dielectric is approximated by the dielectric capacitor (Cdep) and the sheath region with the sheath resistance (Rs) and the sheath capacitor (Cs) and the thickness of the dielectric is calculated, there is an advantage in that the state of the dielectric can be easily grasped. If data outside the error range set by the user is obtained while monitoring the thickness of the dielectric during the deposition process or after the process is completed, what is the state of the plasma, whether it is performed according to the discharge conditions inside the chamber 40, and whether the deposition process is smoothly performed qualitative analysis can be performed. When data is extracted outside the actual error range, there is an advantage in that the deposition process can be quickly stopped, plasma discharge conditions can be changed, or plasma deposition equipment can be repaired.

In addition, since the plasma process monitoring apparatus 100 according to the present invention measures the thickness of a dielectric by applying a multi-frequency voltage and measuring the corresponding current, after applying the voltage and measuring the current, the phase difference is used to measure the dielectric thickness. In a conventional device for measuring the thickness of, the principle of the present invention may be additionally applied to measure the thickness of a dielectric.

In addition, when measuring the thickness of a relatively thick dielectric, the plasma process monitoring apparatus 100 according to the present invention measures the thickness of the dielectric considering the fringing effect generated by the electric field at the edge of the dielectric. , it is possible to derive a measured value very similar to the thickness of the actual dielectric.

In general, the electric field passing through the insulator occurs perpendicular to the plate, but the edge part (side part) is formed by bending due to its nature, and this part is called the fringing effect (extra effective cross-sectional area). And since this fringing effect also occurs inside the chamber, when the thickness of the dielectric is measured without considering this phenomenon, a result value slightly different from the actual thickness of the dielectric may be calculated.

However, the plasma process monitoring device 100 according to the present invention can calculate the thickness of the dielectric considering these effects. Specifically, the actual area A and An equation for the effective area Aeff considering other fringing effects can be derived as shown in Equation (6) below.

When the corresponding formula is applied to the inventive device, precise measurement is possible even in a thick dielectric. Figure 6 is a view showing the difference between the measured value and the actual result when the thickness of the dielectric is measured in consideration of the fringing effect. It can be seen that the thickness of the quartz plate up to can be accurately measured.

7 is a diagram showing actual experimental results when the thickness of a dielectric is measured using an equivalent circuit model according to an embodiment of the present invention, and FIG. 8 is a view showing a plasma process monitoring method according to the present invention in a plasma chamber. 9 is a view showing experimental results when the thickness of a dielectric is measured by applying the plasma process monitoring method according to the present invention to a display process chamber. am.

Referring to FIG. 7 , it can be seen that deposition thickness measurement and reproducibility of 99% or more were achieved by accurately measuring the capacitance of capacitors constituting the equivalent circuit model using the equivalent circuit model according to an embodiment of the present invention.

In FIG. 8, when the plasma process monitoring method according to the present invention was installed in an actual plasma chamber to measure the thickness of the dielectric, the inventive device accurately measured the thickness of the simulated dielectric even when the plasma density and electron temperature were changed. 9, it can be seen that the plasma process monitoring method according to the present invention can accurately measure the thickness of the dielectric inside the chamber in real time even in a display process environment.

In recent semiconductor processes, edge rings are used to increase the uniformity of plasma in contact with wafers. generate

However, the plasma process monitoring device and the plasma generating device according to the present invention can relatively accurately measure the thickness of the edge ring in real time using the method described above. Therefore, the data processing unit 120 of the plasma process monitoring device calculates a difference value between the measured thickness and a preset reference thickness, and determines that a lot of wear has progressed when the calculated difference value is out of the preset value, and FIG. 10 As shown in , high uniformity of plasma can be continuously maintained by moving the edge ring by the amount of wear. Meanwhile, the edge ring may be moved by the controller 121 .

So far, a plasma process monitoring device, a plasma generating device, and a plasma process monitoring method according to an exemplary embodiment have been described through drawings.

The plasma process monitoring method and process monitoring device according to an embodiment can accurately calculate the thickness of the actually deposited dielectric without being affected by the discharge conditions unlike the prior art, even if the discharge conditions applied to the chamber are changed, Even when the dielectric is being produced while the deposition process is being performed, there is an advantage of being able to monitor the thickness of the dielectric in real time.

In addition, since the thickness of the dielectric is measured based on the measured impedance value rather than the phase difference of the current, it is possible to measure the thickness more precisely than in the prior art. There is an advantage that can accurately measure the thickness of.

In addition, since the plasma process monitoring method and the process monitoring device according to an embodiment can measure the thickness of the edge ring installed for the uniformity of the plasma generated inside the chamber in real time, it is determined that the edge ring is worn out a lot. In this case, there is an advantage in maintaining the uniformity of the plasma by moving the edge ring upward.

The devices described above may be implemented as hardware components, software components, and/or a combination of hardware components and software components. For example, devices and components described in the embodiments may include, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA), It may be implemented using one or more general purpose or special purpose computers, such as a programmable logic unit (PLU), microprocessor, or any other device capable of executing and responding to instructions. The processing device may run an operating system (OS) and one or more software applications running on the operating system. A processing device may also access, store, manipulate, process, and generate data in response to execution of software. For convenience of understanding, there are cases in which one processing device is used, but those skilled in the art will understand that the processing device includes a plurality of processing elements and/or a plurality of types of processing elements. It can be seen that it can include. For example, a processing device may include a plurality of processors or a processor and a controller. Other processing configurations are also possible, such as parallel processors.

Software may include a computer program, code, instructions, or a combination of one or more of the foregoing, which configures a processing device to operate as desired or processes independently or collectively. You can command the device. Software and/or data may be any tangible machine, component, physical device, virtual equipment, computer storage medium or device, intended to be interpreted by or provide instructions or data to a processing device. can be embodied in Software may be distributed on networked computer systems and stored or executed in a distributed manner. Software and data may be stored on one or more computer readable media.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer-readable medium. Examples of computer-readable recording media include hard disks, floppy disks, and magnetic tapes. Magnetic media, optical media such as CD-ROM and DVD, magneto-optical media such as floptical disks, and ROM, RAM ( RAM), flash memory, etc., hardware devices specially configured to store and execute program instructions. Examples of program instructions include high-level language codes that can be executed by a computer using an interpreter, as well as machine language codes such as those produced by a compiler.

As described above, although the embodiments have been described with limited examples and drawings, those skilled in the art can make various modifications and variations from the above description. For example, the described techniques may be performed in an order different from the method described, and/or components of the described system, structure, device, circuit, etc. may be combined or combined in a different form than the method described, or other components may be used. Or even if it is replaced or substituted by equivalents, appropriate results can be achieved. Therefore, other implementations, other embodiments, and equivalents of the claims may fall within the scope of the following claims.

Claims

a chamber in which plasma is generated;

at least one sensor disposed inside the chamber;

a voltage applicator for applying three or more voltages having different frequencies to the sensor;

a measuring circuit unit measuring an output current flowing through the sensor; and

A plasma generating device including a; data processing unit for calculating the thickness of the dielectric in the chamber based on the information on the sine wave voltage and the information on the output current.
According to claim 1,

The data processing unit,

A plasma generating device for calculating the thickness of the dielectric using an equivalent circuit model with a circuit configuration of a dielectric capacitor generated by depositing the dielectric, a sheath capacitor in a sheath region generated adjacent to the plasma, and a sheath resistance.
According to claim 1,

The three or more voltages,

A plasma generating device comprising three or more sinusoidal voltages having different frequencies.
According to claim 3,

The three-phase sinusoidal voltage includes a first sinusoidal wave, a second sinusoidal wave, and a third sinusoidal wave,

The voltage application unit,

Wherein the first sinusoidal wave, the second sinusoidal wave, and the third sinusoidal wave are simultaneously applied or applied with a time difference.
According to claim 4,

The data processing unit,

When the first sinusoidal wave, the second sinusoidal wave, and the third sinusoidal wave are applied, the thickness of the dielectric is calculated based on the magnitude of the measured current and the impedance information of the equivalent circuit model, respectively. Plasma generating device.
According to claim 2,

The data processing unit,

Plasma generator for re-calculating the thickness of the dielectric based on information calculated in consideration of a fringing effect generated in the dielectric.
According to claim 2,

The data processing unit,

A plasma generating device that calculates a thickness of an edge ring in the chamber based on the information about the sine wave voltage and the information about the output current.
According to claim 7,

After calculating the difference between the calculated thickness of the edge ring and the preset reference thickness, if the difference is out of a preset range, a control unit for moving the edge ring upward by the difference; further comprising, plasma generation Device.
a voltage applicator for applying three or more sinusoidal voltages having different frequencies to at least one sensor disposed inside a chamber in which plasma is generated;

a measuring circuit unit measuring an output current flowing through the sensor; and

A plasma process monitoring apparatus comprising a; data processing unit for calculating the thickness of the dielectric in the chamber based on the information on the sine wave voltage and the information on the output current.
According to claim 9,

The data processing unit,

A plasma process monitoring device for calculating the thickness of the dielectric using an equivalent circuit model with a circuit configuration of a dielectric capacitor generated by depositing the dielectric, a sheath capacitor in a sheath region generated adjacent to the plasma, and a sheath resistance.
According to claim 10,

The three or more sinusoidal voltages include a first sinusoidal wave, a second sinusoidal wave, and a third sinusoidal wave having different frequencies,

The voltage applying unit simultaneously applies the first sinusoidal wave, the second sinusoidal wave, and the third sinusoidal wave, or applies them with a time difference.

The data processing unit calculates the thickness of the dielectric based on the magnitude of the current measured respectively and the impedance information of the equivalent circuit model when the first sinusoidal wave, the second sinusoidal wave, and the third sinusoidal wave are applied, plasma process monitoring device.
According to claim 10,

The data processing unit,

Plasma process monitoring apparatus for re-calculating the thickness of the dielectric based on information calculated in consideration of a fringing effect occurring in the dielectric.
According to claim 10,

The data processing unit,

Plasma process monitoring apparatus for calculating the thickness of the dielectric in the chamber based on the information on the sine wave voltage and the information on the output current.
According to claim 13,

After calculating the difference between the calculated thickness of the edge ring and a preset reference thickness, and when the difference is out of a preset range, a control unit for moving the edge ring upward by the difference; further comprising a plasma process. monitoring device.
A voltage application step of applying three or more sinusoidal voltages having different frequencies to at least one sensor disposed inside a chamber in which plasma is generated;

a current measuring step of measuring an output current flowing through the sensor; and

A data processing step of calculating a thickness of a dielectric inside the chamber based on the information on the sine wave voltage and the information on the output current; including, a plasma process monitoring method.