JP2021188940A - Measurement abnormality detector and measurement abnormality detection method - Google Patents

Abstract

To provide a measurement abnormality detector that makes it possible to detect a specific change in the temporal change rate of film thickness, and a measurement abnormality detection method.SOLUTION: Provided is a measurement abnormality detector for detecting measurement abnormality with a crystal resonator when calculating the temporal change rate of film thickness accumulated in the crystal resonator, using a correlation between transmission to the crystal resonator and reception from the crystal resonator. A control device 20 sets a criterion to the phase or imaginary part derived from the correlation and ascertains a sample by the criterion that can accommodate measurement abnormality, then evaluates whether or not the temporal change amount of the sample is attributable to said measurement abnormality and thereby detects measurement abnormality.SELECTED DRAWING: Figure 1

Description

The present invention relates to a measurement abnormality detection device for detecting measurement abnormality of deposits deposited on a crystal oscillator, and a measurement abnormality detection method.

The above-mentioned device for measuring the film thickness is mounted on a film forming apparatus such as a vacuum vapor deposition apparatus. The QCM (Quartz Crystal Microbalance) method adopted by the film thickness measuring device measures the film thickness of the deposit from the series resonance frequency and half-value half width obtained by vibrating the crystal unit, and the crystal unit has a product life. It is used to detect that the frequency has been reached (see, for example, Patent Documents 1, 2, 3 and Non-Patent Document 1). The relationship between the series resonance frequency of the crystal unit and the film thickness is expressed by, for example, the following equation (1). The relationship between the half width at half maximum and the film thickness of the crystal oscillator is shown by, for example, the following equation (2). It should be noted that 1/2 of the conductance at the series resonance frequency is a half value, and 1/2 of the total width at the half value of the function drawing the mountain shape with the series resonance frequency as the apex is the half width. In the following equation (2), 1/2 of the full width at half maximum is also expressed as half width Fw. The difference ΔFw is the fluctuation amount of the half-value half-width Fw, and corresponds to the fluctuation amount of the half-value half-width Fw between two different film thicknesses.

The following equation (1) is used when the series resonance frequency in the crystal unit at the time of deposition is used as the input of the system. The formula (1) is mainly used when a relatively hard film such as a metal or a metal oxide is deposited on the crystal unit.

The following equation (2) is used when the complex elastic modulus G and the loss elastic modulus G "are used as input of the system. That is, the crystal at the time of deposition in the calculation of the complex elastic modulus G and the loss elastic modulus G". It is used when the series resonance frequency and half-value frequency of the vibrator are used as the input of the system. As the series resonance frequency, a fundamental wave and an n-fold wave such as a third harmonic of the fundamental wave may be used. Equation (2) is used when a relatively soft film such as an organic film is deposited on the crystal unit.

The difference between the configuration using the equation (1) and the configuration using the equation (2) is that the configuration in the measurement can be simplified because the equation (1) uses only the series resonance frequency. On the other hand, in the equation (2), since the half-value frequency is added as a variable, the number of input dimensions to be derived increases, that is, the number of calculation steps increases, and the configuration in the measurement mainly uses the equation (1). Although it is more complicated than the configuration, it can be expected to improve the measurement accuracy. If the n-fold wave or the like described in Patent Document 4 is used, the improvement in measurement accuracy becomes more remarkable.

式（１）において、ρ_ｆは堆積物の密度、ｔ_ｆは堆積物の膜厚、ρ_ｑは水晶振動子の密度、ｔ_ｑは水晶振動子の膜厚、Ｚは音響インピーダンス比、ｆ_ｑは未堆積時の水晶振動子における直列共振周波数である。密度ρ_ｆ、密度ρ_ｑ、膜厚ｔ_ｑ、音響インピーダンス比Ｚ、および、直列共振周波数ｆ_ｑは、一般的に定数として扱うことが可能である。式（１）において、ｆ_ｃは堆積時の水晶振動子における直列共振周波数であり、一般的に測定可能な値であり入力値とすることができる。この変数である入力値と上述した各定数を利用することによって、堆積物の膜厚ｔ_ｆは、変数である直列共振周波数ｆ_ｃの値が定まれば算出することができ、言い換えれば、膜厚ｔ_ｆ＝ｆ（直列共振周波数ｆ_ｃ）のように、直列共振周波数ｆ_ｃの関数として表記することができる。

In equation (1), ρ _f is the density of the deposit, t _f is the film thickness of the deposit, ρ _q is the density _{of the crystal oscillator, t q} is the film thickness of the crystal oscillator, Z is the acoustic impedance ratio, and f _q. Is the series resonance frequency of the crystal unit when it is not deposited. The density ρ _f , the density ρ _q , the film thickness t _q , the acoustic impedance ratio Z, and the series resonance frequency f _q can generally be treated as constants. In the equation (1), f _c is a series resonance frequency in the crystal unit at the time of deposition, which is generally a measurable value and can be used as an input value. By utilizing the constants mentioned above the input value is the variable, the thickness t _f of the deposit can be calculated if Sadamare the value of the series resonance frequency f _c is variable, in other words, film It can be expressed as a function of the series resonance frequency f _c , such as thickness t _f = f (series resonance frequency f _c).

In the formula (2), the difference ΔFw is obtained as the difference between the _{half-value half-width Fw q} in the undeposited crystal oscillator and the half-value half-width Fw _{c in the crystal oscillator at the time of deposition. The half-value half-width Fw c} in the crystal unit at the time of deposition is generally a measurable value and can be used as an input value. The difference ΔFw can also be obtained by using the parameters described below as shown on the right side of the equation (2). G is the complex elastic modulus, G'is the storage elastic modulus, G "is the loss elastic modulus _{. Ω is the angular frequency, F 0} is the fundamental frequency, and Z _q is the shear mode acoustic impedance of the crystal. Complex elastic modulus G, The storage elastic modulus G'and the loss elastic modulus G'are measured by measuring the series resonance frequency and the half-value frequency of the crystal oscillator at the time of deposition by using the method described in the preceding technical literature, and the measurement result is a variable. It can be obtained by using it as an input value. The series resonance frequency can also be obtained by combining a fundamental wave and an n-fold wave such as a third harmonic thereof. If equation (2) is used, the series resonance frequency f _c and the half-value frequency are input values that are variables, and the film thickness t _{f of the} deposit is the film film t _f = f (series resonance frequency f _c , half-value frequency). as a), it can be expressed as a function of the series resonance frequency f _c and the half frequency.

Japanese Patent No. 6078694 Republished Patent No. 2016/031138 JP-A-2019-65391 Japanese Patent No. 5372263

Sensors and Actuators B37: (1996) 111-116

The heat capacity of the vapor deposition source that sublimates the vapor deposition material is usually designed to be a very large value from the viewpoint of increasing production efficiency, and has a size that does not easily fluctuate at a time interval of about several minutes. .. That is, among the fluctuations in the time change rate of the film thickness that may occur due to the fluctuation of the evaporation amount of the vaporized material in the vapor deposition source, the fluctuation that exceeds the influence of the fluctuation of the degree of vacuum is usually a number. It cannot occur at time intervals of about minutes. On the other hand, it is newly recognized that even with the time change rate of the film thickness obtained by using the above formula (1), a specific change can occur at a time interval of about several minutes. The specific change in the time change rate of the film thickness is that the time change rate of the series resonance frequency in the crystal unit at the time of deposition suddenly decreases and returns to the original value after a few minutes have passed. It is a phenomenon. To explain the rate of change in film thickness over time as a so-called velocity, acceleration is usually regarded as a constant, but when a specific change occurs, it exceeds the range that can be regarded as a constant. Can be explained. It should be noted that the acceleration returns to the range that can be regarded as a constant after a few minutes have passed from the time when the specific change occurs.

FIG. 9 is a graph showing an example of the above-mentioned specific change, and is a graph showing the time change rate of the film thickness recognized when the above formula (1) is used as a time transition. FIG. 10 is an enlarged graph showing a part of FIG. 9. As shown in FIG. 9, it is recognized that the specific change in the time change rate of the film thickness described above is an event in which the acceleration described above changes and can occur non-stationarily. As shown in FIG. 10, in the specific change in the time change rate of the film thickness, the time change rate of the stable film thickness suddenly increases at a magnitude of about 10%, but it is several minutes to several tens of minutes. After the time interval, it returns to the time change rate before the rise.

In this way, the specific change in which the time change rate of the film thickness suddenly rises and returns in a short time cannot be said to be caused by the fluctuation of the heat capacity of the vapor deposition source, and it cannot be said that it can occur in a short time. It cannot be said that the change in the rate of change over time, which returns with, affects the entire film-deposited object. However, in the film forming apparatus that feedback-controls the time change rate of the film thickness to the temperature of the vapor deposition source, the output of the vapor deposition source is temporarily lowered based on the sudden increase in the time change rate due to the specific change, and the film formation is performed. The rate of change in film thickness over time in the subject is actually reduced. Then, the output of the vapor deposition source is increased based on the sudden return of the time change rate in the specific change, and the time change rate of the film thickness is actually vibrated.

An object of the present invention is to provide a measurement abnormality detection device capable of detecting a specific change in the time change rate of a film thickness, and a measurement abnormality detection method.

The measurement abnormality detecting device for solving the above problem is used when calculating the time change rate of the film thickness deposited on the crystal oscillator by using the correlation between the transmission to the crystal oscillator and the reception from the crystal oscillator. In addition, it is a measurement abnormality detection device that detects a phenomenon in which the time change rate of the film thickness temporarily increases or decreases as a measurement abnormality. The possible measurement abnormality is detected by determining a possible sample according to the standard and evaluating whether or not the amount of time change of the sample is due to the measurement abnormality.

A measurement abnormality detection method for solving the above problems is when calculating the time change rate of the film thickness deposited on the crystal oscillator by using the correlation between the transmission to the crystal oscillator and the reception from the crystal oscillator. In addition, it is a measurement abnormality detection method that detects a phenomenon in which the time change rate of the film thickness temporarily increases or decreases as a measurement abnormality. The possible measurement abnormality is detected by determining a possible sample according to the standard and evaluating whether or not the amount of time change of the sample is due to the measurement abnormality.

As described above, it is newly recognized that even the time change rate of the film thickness obtained by using the above formula (1) can cause a specific change at a time interval of several minutes to several tens of minutes. There is. The specific change in the time change rate of the film thickness is that the time change rate of the series resonance frequency in the crystal oscillator suddenly fluctuates and returns at time intervals of several minutes to several tens of minutes. The present inventors have found that the above-mentioned specific changes tend to be observed deviationally in the crystal unit in the diligent study of such specific changes. In addition, in the detailed analysis of the correlation between transmission and reception when the above-mentioned specific change occurs, a standard is set for the phase or imaginary part used for calculating admittance in the crystal oscillator, and the standard is used. We have found that the amount of time variation of a sample, such as the real part of the determined admittance, largely follows the specific change. Then, it is presumed that the above-mentioned specific change is caused not by noise or the like but by the instantaneous structural change of the sediment, and a means capable of separating this specific change has been created.

With the above configuration, first, a reference is set for the phase or imaginary part derived from the correlation, and the amount of time change of the sample determined by the reference is calculated. Then, the measurement abnormality is detected by evaluating whether or not the amount of time change of the sample is due to the measurement abnormality. A sample determined by a reference provided in the phase or imaginary part derived from the correlation is a sample that follows the specific changes described above, for example, as compared to a sample determined by a time-varying criterion. It reacts accurately to the above-mentioned specific changes that change. As a result, the change in the amount of time change of the sample described above makes it possible to detect with high accuracy a sudden increase estimated to return in a short time in the time change rate of the film thickness, and thus the time change of the film thickness. It is possible to accurately detect the specific change that occurs in the rate.

The reference provided by the phase or imaginary part derived from the correlation is the measured value of the physical quantity used in the mathematical formula group used when calculating the time change rate of the film thickness, or the measured value of 1 or more. It is a calculated value calculated using, and further, a range of measured values or a range of calculated values. The reference provided for the phase or imaginary part derived from the correlation is, for example, the phase or imaginary part used for calculating admittance, or the phase or imaginary part used for calculating impedance. The sample determined by the standard is the measured value used in the mathematical formula group used when calculating the time change rate of the film thickness, the calculated value calculated using one or more measured values, and further. , A range of measured values, or a range of calculated values, such as the real part of admittance and the real part of impedance.

In the above configuration, the reference may be an imaginary part of admittance in the crystal oscillator, and the sample may be a real part of admittance in the crystal oscillator. According to this configuration, it is possible to determine with high accuracy that the sudden increase in the rate of change in film thickness over time is the above-mentioned specific change.

In the above configuration, a calculation unit that calculates the time change rate of the film thickness, a detection unit that determines that the time change amount of the sample is out of the normal range, and the detection unit detects the measurement abnormality. It may be provided with a control unit that executes a hold process for holding the calculation result in the calculation unit immediately before the measurement and releases the hold process when the time change amount of the sample returns to the normal range. ..

According to the above configuration, it is possible to output a value closer to the original value as the time change rate of the film thickness over the period during which the hold process is performed, that is, during the period during which a specific change occurs. It will also be possible. Then, after the hold process is completed, it is possible to recalculate the original value of the time change rate of the film thickness by using the system in which the specific change has occurred.

In the above configuration, the time change amount of the sample obtained by using the first sensor unit for collecting the correlation and the second sensor unit for collecting the correlation and using one of the sensor units. When the measurement abnormality is detected in the evaluation of the above, the time change rate of the film thickness may be calculated using the correlation collected by the other sensor unit.

According to the above configuration, the other sensor unit is used for the period in which the above-mentioned specific change is occurring, whereby the original value can be calculated as the time change rate of the film thickness. Then, when a measurement abnormality is detected in the evaluation of the time change amount of the sample obtained by using the other sensor unit, one sensor unit is used, thereby calculating the original value as the time change rate of the film thickness. It becomes possible. As a result, it becomes possible to continuously and accurately calculate the time change rate of the film thickness.

In the above configuration, even if two electrodes are located on the side surface of the crystal unit facing the vapor deposition source, the first sensor unit includes one electrode, and the second sensor unit includes the other electrode. good.

According to the above configuration, it is possible to continuously calculate the time change rate of the film thickness, which can be said to be the original value, by using a single crystal unit.

The block diagram which shows the structure of the measurement abnormality detection apparatus provided in one Embodiment of the film thickness measuring apparatus. The circuit diagram which shows the equivalent circuit of a crystal oscillator together with the block diagram of a sensor part. The graph which shows the series resonance frequency and the half-value frequency in a conductance waveform. A graph showing the relationship between the imaginary part of admittance and the time change rate of the film thickness. A graph showing the relationship between the real part difference value of admittance and the time change rate of the film thickness. The graph which shows the time transition which expanded a part of FIG. The graph which shows the time transition which expanded the other part of FIG. The graph which shows the relationship between the real part difference value of admittance and the time change rate of a film thickness at the time of power supply cutoff of a thin-film deposition source. The graph which shows the time transition of the time change rate of the film thickness. The graph which shows the time transition which expanded a part of FIG.

Hereinafter, an embodiment of the measurement abnormality detection device and the measurement abnormality detection method will be described with reference to FIGS. 1 to 8. In this embodiment, an example in which a film thickness measuring device including a measurement abnormality detecting device is mounted on the film forming device will be described. The film thickness measuring device measures the film thickness and determines an abnormality in the film thickness measurement. An example of performing feedback control on the time change rate of the film thickness of the vapor-deposited material based on the film thickness output from the film thickness measuring device and the determination result will be described.

As shown in FIG. 1, the film forming apparatus includes a vacuum chamber 11. The vacuum chamber 11 houses the vapor deposition source 12 and the detection device 14 inside. The vapor deposition source 12 is connected to an external power source 13. The vapor deposition source 12 receives electric power from the power source 13 and sublimates the vapor deposition material toward a substrate (not shown).

The sublimation method in the vapor deposition source 12 is, for example, a resistance heating type, an induction heating type, an electron beam heating type, or the like. The vapor deposition material is an organic material, a metal material, a metal compound material such as a metal oxide or a metal nitride. The substrate is a semiconductor substrate, a quartz substrate, a glass substrate, a resin film, or the like. The deposited material is deposited in much the same way on the substrate and the detector 14.

The film thickness measuring device includes a detection device 14 and a control device 20. The control device 20 includes a control unit 21, a storage unit 22, a measurement unit 23, and an abnormality detection unit 24. The control device 20 has a function of controlling the film forming apparatus in addition to the function of controlling the detection device 14.

The detection device 14 includes a crystal oscillator. The crystal oscillator has a predetermined series resonance frequency as a natural frequency. The material constituting the crystal oscillator is, for example, an AT-cut type crystal oscillator or an SC-cut type crystal oscillator. The series resonance frequency of the crystal oscillator is, for example, 3 MHz or more and 6 MHz or less.

The detection device 14 is used to measure the film thickness of the deposit deposited on the substrate and the time change rate of the film thickness. The measured value and the calculated value related to the film thickness and the time change rate of the film thickness are used in the film forming apparatus as the feedback amount of the processing performed by the film forming apparatus. The detection device 14 is arranged in the vacuum chamber 11 so as to face the vapor deposition source 12. The detection device 14 receives a transmission signal from the measurement unit 23, vibrates and oscillates together with deposits deposited on the surface of the crystal oscillator, and at the same time receives the vibration to generate an electric signal, and this electric signal is generated. Is output to the control device 20.

The surface of the crystal oscillator is arranged so as to face the vapor deposition source 12. As shown in FIG. 2, electrodes 14A1, 14A2, 14C for vibrating the crystal oscillator 14B are located on the front surface and the back surface of the crystal oscillator 14B. The vapor deposition material is deposited from the vapor deposition source 12 on the surface common to the two electrodes 14A1 and 14A2 at arbitrary time intervals.

The first sensor unit is composed of one electrode 14A1, a crystal oscillator 14B, and an electrode 14C located on the back surface. The second sensor unit is composed of another electrode 14A2, a crystal oscillator 14B, and an electrode 14C located on the back surface. The detection device 14 is configured so that the sensor unit for measurement can be switched between the first sensor unit and the second sensor unit based on the input from the control device 20 to any of the terminals T1 and T2. The detection device 14 sets an electrode used for transmission to the crystal oscillator 14B and reception from the crystal oscillator 14B to either the electrode 14A1 or the electrode 14A2. The number of electrodes located on the surface of the crystal oscillator may be one or three or more.

The thin-film deposition material deposited on the surface of the crystal oscillator 14B changes the vibration frequency of the crystal oscillator 14B as a newly added mass at an arbitrary time interval. The mass of the deposit on the surface of the crystal unit 14B correlates with the density of the deposit. By using the correlation between the transmission to the crystal oscillator 14B and the reception from the crystal oscillator 14B, the film thickness deposited on the crystal oscillator 14B and the time change rate thereof can be calculated. The film thickness measuring device transmits transmission to the crystal oscillator 14B, and indirectly measures the film thickness and its time change rate from the vibration waveform of reception which is the response of the transmission.

The film thickness measuring device uses an AC signal, which is a frequency signal, typically a sine wave as a vibration source. The excited crystal oscillator 14B responds as a system including deposits adhering to the surface. The film thickness measuring device detects the response of the crystal oscillator including the mechanical vibration phenomenon as an electrical vibration waveform via the piezoelectric effect of the crystal oscillator 14B. The film thickness measuring device stores the waveform that is the detection result and analyzes the stored waveform. The film thickness measuring device extracts and outputs the film thickness included in the waveform analysis result.

FIG. 2 shows a system that responds to vibration by an equivalent circuit. The equivalent circuit shown in FIG. 2 is also referred to as a measurement system. As shown in FIG. 2, the crystal oscillator 14B is shown as a parallel circuit of a series resonance circuit composed of an equivalent series capacitance C1, an equivalent series inductance L1, and an equivalent series resistance R1 and a parallel capacitance C0. The series resonant circuit is an equivalent circuit including the mechanical vibration element of the crystal oscillator 14B. The equivalent circuit shown in FIG. 2 is an example in which one electrode is located on the surface of the crystal oscillator 14B, and in a configuration in which a plurality of electrodes 14A1 and 14A2 are located on the surface of the crystal oscillator 14B, the equivalent circuit is used. It is shown as another equivalent circuit in which a plurality of constituent circuit elements exist.

The parallel capacitance C0 is a capacitance between the electrodes 14A1 and 14A2 and the electrode 14C including the parasitic capacitance of the package for holding the crystal oscillator 14B. The equivalent series resistance R1 indicates a vibration loss component such as internal friction, mechanical loss, and acoustic loss when the crystal oscillator 14B vibrates. The higher the equivalent series resistance R1, the less likely the crystal oscillator 14B will vibrate.

The imaginary part of admittance and the imaginary part of impedance in the crystal oscillator 14B are values that can be specified as calculated values using the equivalent series capacitance C1, the equivalent series inductance L1, and the equivalent series resistance R1. The real part of admittance and the real part of impedance in the crystal oscillator 14B are values that can be specified as calculated values using the equivalent series capacitance C1, the equivalent series inductance L1, and the equivalent series resistance R1.

Returning to FIG. 1, the control device 20 includes a control unit 21, a storage unit 22, a measurement unit 23, and an abnormality detection unit 24. The measuring unit 23 may include at least one of the first measuring unit 23A and the second measuring unit 23B. That is, the measuring unit 23 may have a configuration in which the first measuring unit 23A is omitted or a configuration in which the second measuring unit 23B is omitted. The control device 20 mainly controls the processing performed by the film forming apparatus, and the control unit 21 mainly controls the processing performed by the film thickness measuring apparatus.

The control device 20 supplies electric power to the power supply 13 to sublimate the vapor deposition material from the vapor deposition source 12 toward the substrate. The control device 20 feedback-controls the output power of the power supply 13 so that the time change rate of the film thickness becomes the target value by using, for example, the time change rate of the film thickness obtained from the control unit 21. When the film formation using the vapor deposition source 12 is started, the control unit 21 reads the measurement program, the measurement abnormality detection program, etc. stored in the storage unit 22 and executes the read program for measurement. Execute the abnormality detection method.

The control unit 21 causes the detection device 14 to input an AC signal from the measurement unit 23. In the configuration including the first measuring unit 23A, the control unit 21 causes the first measuring unit 23A to measure, for example, the series resonance frequency Fs. In the configuration including the second measurement unit 23B, the control unit 21 sweeps the frequency of the AC signal in the vicinity of the series resonance frequency Fs of the crystal oscillator, thereby performing the series resonance frequency Fs, the half-value frequencies F1, F2, and the half-value frequency. The width is measured by the second measuring unit 23B.

The control unit 21 stores the vibration waveform, which is the response of the detection device 14, in the storage unit 22. The control unit 21 stores various values handled by the measurement unit 23 and the abnormality detection unit 24 in the storage unit 22. The control unit 21 analyzes the vibration waveform, or causes the measurement unit 23 to analyze the vibration waveform. The control unit 21 calculates the film thickness at a predetermined time interval, that is, the time change rate of the film thickness, or causes the measurement unit 23 to calculate the film thickness. The control unit 21 causes the abnormality detection unit 24 to process various values input from the measurement unit 23. The measurement unit 23 functions as an example of the calculation unit, and the abnormality detection unit 24 functions as an example of the detection unit.

When the control unit 21 receives from the control device 20 that the film formation is completed, the control unit 21 ends the execution of the measurement program.
The control unit 21 is composed of, for example, hardware elements used in a computer such as a CPU, RAM, and ROM, and software. The control unit is not limited to processing all kinds of processing by software. For example, the control unit may include an integrated circuit (ASIC) for determination applications, which is dedicated hardware that executes at least a part of various processes. The control unit may be configured as a circuit including one or more dedicated hardware circuits such as an ASIC, a microcomputer which is one or more processors operating according to software which is a computer program, or a combination thereof. ..

The storage unit 22 contains various values such as a reference result, a sample result, a voltage vibration waveform, a vibration frequency range, a vibration signal waveform which is a transmission signal waveform, a film thickness measurement program, a measurement abnormality detection program, and a measurement abnormality detection program. , Stores various data such as normal range. The various waveforms include a sine wave, a square wave, a triangular wave, and a white noise signal, and include a duty ratio and the like as values related to the various waveforms.

The control unit 21 reads various values and measurement programs stored in the storage unit 22 and data, and executes the measurement program to cause the measurement unit 23 to execute various processes. The control unit 21 reads various values stored in the storage unit 22, the measurement abnormality detection program, and the data, and executes the measurement abnormality detection program to cause the measurement unit 23 and the abnormality detection unit 24 to perform various processes. To execute.

The first measuring unit 23A is configured to be able to measure the series resonance frequency Fs of the crystal oscillator in cooperation with the storage unit 22 and the control unit 21. The first measurement unit 23A includes, for example, a transmission circuit and a measurement circuit.

The transmission circuit oscillates the crystal oscillator using an AC signal as a vibration signal, and the crystal oscillator included in the detection device 14 has a specific frequency such as the series resonance frequency Fs of the crystal oscillator when it is not deposited or a frequency in the vicinity thereof. Enter the frequency to vibrate the crystal unit. The measuring circuit measures, for example, a voltage vibration waveform which is a received signal as an attenuation response after stopping oscillation, and records the result in the storage unit 22.

The control unit 21 calculates various resonance characteristic values for the recorded voltage vibration waveform in order to calculate the time change rate of the film thickness by using a known analysis method prepared in advance. An example of an analysis method is a method using exponential attenuation (hereinafter, also referred to as Ring-down analysis). Ring-down analysis is an analysis method that utilizes the fact that the fluctuating mass added to the surface of the crystal oscillator can be observed as the kinetic energy release fluctuation during the damping response.

The control unit 21 can be a reference for detecting a measurement abnormality due to a specific change from the correlation between transmission and reception by using a known analysis method prepared in advance for the recorded voltage vibration waveform. Calculate the value or range. Further, the control unit 21 calculates a value or a range that can be a sample by using a known analysis method prepared in advance.

The second measurement unit 23B functions as a network analyzer. The second measuring unit 23B measures a value or range that can be a reference, a value that can be a sample, or a range, a series resonance frequency Fs, half-value frequencies F1 and F2, etc., without coordinating with the storage unit 22 and the control unit 21. It is configured to be possible.

The second measurement unit 23B includes a transmission circuit and a measurement circuit. The second measurement unit 23B is configured to remove the vibration signal supplied to the crystal oscillator from the voltage vibration waveform which is the response on which the vibration signal is superimposed, and to be able to separate only the response signal.

The transmission circuit inputs an AC signal as a vibration signal to the crystal oscillator included in the detection device 14. For the excitation signal, for example, a sinusoidal sweep method in the vicinity of the series resonance frequency Fs of the crystal oscillator is used. The measurement circuit is, for example, a value or range that can be a reference, a value or range that can be a sample, and a series resonance frequency Fs, half-value frequencies F1, F2, and half-value half-width Fw calculated by using these from the response signal. Ask for.

As described above, if the measurement unit 23 is provided with the first measurement unit 23A or the second measurement unit 23B, the resonance characteristic value in the equation (1) or the equation (2), which is a function for deriving the film thickness, is provided. The input value is obtained. The measurement unit 23 may be configured such that either the first measurement unit 23A or the second measurement unit 23B is selected by the control unit 21 based on the measurement result. Further, the measuring unit 23 may be configured to calculate variables other than those described in the equations (1) to (6) as necessary.

As shown in FIG. 3, the half-value frequencies F1 and F2 are frequencies that give 1/2 of the maximum value of conductance at the series resonance frequency Fs. The half-value frequency width is twice the half-value half-width Fw, and is a difference value between one half-value frequency F1 and the other half-value frequency F2. The half-value half-width Fw is ½ of the half-value frequency width. The conductance is a real part of admittance, and FIG. 3 shows an example of measurement using a current as a transmission signal and a voltage as a reception signal. As described above, as the series resonance frequency Fs, a fundamental wave and an n-fold wave such as a tripled wave of the fundamental wave can be used. When a single series resonance frequency Fs is selected, the conduction value is generally the maximum when the fundamental wave is used, and the S / N ratio, which is the signal intensity ratio, can be obtained large. , It is preferable to select the fundamental wave as the series resonance frequency Fs.

Here, the deposits deposited on the crystal oscillator 14B continuously change the deposit amount with the passage of time, and the frequency shown on the horizontal axis in FIG. 3 is affected by the fluctuation in the deposit amount. It is a parameter that receives and fluctuates. That is, if a reference is set for the series resonance frequency Fs and the conductance value corresponding to the reference is measured, the series resonance frequency Fs changes with time, so that the reference is sequentially followed by the change of the series resonance frequency Fs. It is necessary to let them find the conductance.

In this regard, if the conductance value is measured in the vicinity of the fundamental wave at the series resonance frequency Fs, the phase difference in the correlation between transmission and reception is theoretically almost 0 °, so the measurement near the maximum value of the conductance value is performed. Since a value (theoretical value) can be obtained and it is a reference that does not change with time, tracking is not required. Further, the fact that the measured value can be made to follow the maximum value of the conductance value because the phase difference is almost 0 ° is the same in the measurement using the n-fold wave of the fundamental wave. At the same time, the fact that tracking is not required also has an effect that can be simplified from the viewpoint of algorithm implementation on the control device and value management.

In the embodiment, a measurement abnormality in which a specific change is observed when the phase difference in the correlation between transmission and reception is approximately 0 ° will be described. In this embodiment, a reference is set for the phase or a reference is set for the imaginary part, the conductance value is determined from this reference, and the time change amount of the sample is evaluated using the conductance value as a sample. As a result, the measurement abnormality described below can be determined with high accuracy.

The Q value and the D value, which are indicators of the accuracy and stability of the oscillation frequency of the crystal oscillator, are represented by the following equations (3) and (4). If the equivalent series capacitance C1 does not change and can be treated as a constant, the equivalent series inductance L1 is represented by the following equation (5) by the series resonance frequency Fs, and the equivalent series resistance R1 is expressed by the following equation (6). Shown. These expressions are stored in the storage unit 22.

制御部２１は、これらの式を利用して各種の値を計算する、あるいは測定部２３に計算させる。例えば、制御部２１は、測定部２３において半値周波数Ｆ１，Ｆ２、および直列共振周波数Ｆｓが得られるごとに、これらの式に基づく計算を時系列的に行う。制御部２１が行う計算は、異常検出部２４が行ってもよい。

The control unit 21 calculates various values using these formulas, or causes the measurement unit 23 to calculate. For example, the control unit 21 performs calculations based on these equations in time series every time the measurement unit 23 obtains the half-value frequencies F1 and F2 and the series resonance frequency Fs. The calculation performed by the control unit 21 may be performed by the abnormality detection unit 24.

The control unit 21 assigns a time index value to the calculated value which is the result of the calculation performed in time series and the measured value used in the calculation according to the time series, and then stores it in the storage unit 22. ..

When the control unit 21 obtains, for example, a series resonance frequency Fs, a value or a range that can be a reference, a value that can be a sample, or a range at the same opportunity, the control unit 21 assigns the same time index value to these values. For example, the control unit 21 assigns the same time index value to the half value frequencies F1 and F2, the series resonance frequency Fs, the reference value or range used in these calculations, the sample value, or the range. The time index value may be assigned by either the measurement unit 23 or the abnormality detection unit 24 in addition to the control unit 21.

The control device 20 executes the iterative process at predetermined time intervals, including the analysis of the correlation described above, and stores the measured value and the calculated value in the storage unit 22 each time the process is executed. The measurement time interval may be fixed as the minimum time within the processable range from the viewpoint of accuracy, but may be variable including a temporary interruption by the control device 20.

The time variation of the repeated processing is recorded in the storage unit 22 as a relative relationship of the time index values. Therefore, the control device 20 performs measurement values and calculations such as a process of setting a reference, a process of determining a sample according to the reference, a process of calculating the amount of time change of the sample, and a process of calculating the time change rate of the film thickness. It is also possible to use the measured value or the calculated value for the numerical processing after the value is stored in the storage unit 22.

Returning to FIG. 1, the abnormality detection unit 24 is configured to be able to use the signal used by the measurement unit 23 for measurement and analysis, and the measured value and calculated value stored by the storage unit 22. The measured values and calculated values stored in the storage unit 22 are voltage vibration waveforms, which are time-response waveforms for transmission and reception, series resonance frequencies Fs, half-value frequencies F1 and F2, equivalent series resistance R1, and film thickness.

The measured value or calculated value stored in the storage unit 22 includes a value or a range that can be a reference and a value or a range that can be a sample. The reference and the sample have a one-to-one correspondence relationship, and are stored as, for example, spreadsheet-like data having a time index value so that the sample is determined by the setting of the reference.

The reference is the value or range of the phase or imaginary part derived from the correlation between the transmission to the crystal unit and the reception from the crystal unit. The reference is a value that does not follow a specific change in the rate of change in film thickness over time, such as a constant susceptance value or a range thereof, or a range thereof. Explaining this correlation in the time domain, the time value or the range of the advance or delay of the received signal with respect to the transmitted signal becomes a reference. It should be noted that the fact that the susceptance value is constant and is almost zero defines the correlation that the transmission to the crystal oscillator and the reception from the crystal oscillator are almost in phase. Explaining the in-phase in the time domain, it means that no advance or delay is observed between the transmitted signal and the received signal. These criteria are set based on the analysis of experiments that generate specific changes. For example, as a result of analysis, when a specific phase difference is set as a reference, the phase corresponds to the ratio to the period, so that the deposit is compared with the case where the advance or delay between the transmitted signal and the received signal is used as a reference. It is not necessary to change the standard according to the time fluctuation, and it can be simplified as described above.

The sample is a value or range determined by the criteria in the correlation between the transmission to the crystal and the reception from the crystal. The sample is a value or a range thereof that can follow the specific change described above, such as a value of conductance when the value of susceptance can be said to be constant, or a range thereof. If the reference is a value, the sample is determined as a value. If the criterion is a range, the sample is defined as a range. These samples are set based on analysis in experiments that generate specific changes.

Susceptance, which is an example of the standard, is expressed as an imaginary part of admittance in a crystal oscillator at a resonance frequency, or as a trigonometric expression using admittance and phase. Reactance, which is an example of the standard, is expressed as an imaginary part of impedance in a crystal oscillator at a resonance frequency, or as a trigonometric expression using impedance and phase. The value or range that can be used as a reference may be another dimensional quantity or a dimensionless quantity by modifying the admittance derivation formula or the impedance derivation formula.

Conductance, which is an example of a sample, is the real part of admittance in a crystal oscillator at a resonant frequency. The resistance, which is an example of the sample, is the real part of the impedance in the crystal unit at the resonant frequency. The sample may also be a dimensionless quantity or a dimensionless quantity by modifying the admittance derivation formula or the impedance derivation formula.

The specific change in the time change rate of the film thickness is that the time change rate of the film thickness suddenly rises once, and after a time interval of several minutes or several tens of minutes, which can be said to be temporary in the vapor deposition process, the original This is a phenomenon in which the time change rate of the series resonance frequency in the crystal oscillator suddenly decreases and returns at time intervals of several minutes to several tens of minutes.

The abnormality detection unit 24 includes a specific unit 25 and a determination unit 26. The anomaly detection unit 24 is configured to handle a combination of two values to which the same time index value is given or a combination of two ranges to which the same time index value is given as a combination of a reference and a sample. There is. When handling the reference and the sample, the measurement unit and the control unit 21 create a group of combinations of the reference and the sample, and after storing the plurality of groups in the storage unit 22, the abnormality detection unit 24 is used. You may use a group.

The specifying unit 25 specifies a value or a range within a preset reference within a value or range that can be a reference stored by the storage unit 22. The preset standard is, for example, a state in which a value or a range that can be a standard can be said to be almost constant in any of the time-series standards. A state in which all the criteria can be said to be almost constant among the time-series criteria can be realized, for example, by recording transmission and reception in the same reference time domain and comparing both in a periodic unit. Specifically, by comparing the phase, the phase difference, and the maximum displacement point with the period as a unit, the time dimensions are canceled out, and a standard that does not change with time can be realized. In the embodiment, a state that can be said to be in phase is used. As another example, the phase difference is a constant value such as 45 ° or a state within a certain range. In this embodiment, it has been confirmed that a particularly large S / N ratio can be obtained as described above when the phase difference is approximately 0 °, which is preferable from the viewpoint of detecting the measurement abnormality. ..

The specific unit 25 determines the sample associated with the specified standard according to the standard. The specific unit 25 captures a sample determined by a time-independent standard according to a processing instruction from the control unit 21. The sampling may be a sequential process synchronized with the process of the measurement unit 23, or may be a process asynchronous with the process of the measurement unit 23 if a time index value is assigned to the reference and the sample. When the sequential processing synchronized with the processing of the measuring unit 23 is performed, the sample taken in the specific unit 25 is given a time index value as an index.

The determination unit 26 calculates the amount of time change of the sample taken in the specific unit 25. For example, when the sample determined by the specific unit 25 is a value, the amount of time change between the sample to which the previous time index value is given and the sample to which the current time index value is given is the sample. Calculated as the amount of change over time. For example, when the sample determined by the specific unit 25 is a range, the median value in the sample to which the previous time index value is given and the median value in the sample to which the current time index value is given are between. The time change amount of is calculated as the time change amount of the sample. Alternatively, when the sample determined by the specific unit 25 is a range, between the minimum value in the sample to which the previous time index value is given and the maximum value in the sample to which the current time index value is given. The time change amount of is calculated as the time change amount of the sample.

The unit time that determines the amount of time change of the sample, that is, the time interval between the previous time index value and the current time index value is the same as the unit time that determines the time change rate of the film thickness. The unit time for determining the time change amount of the sample may be shorter than the unit time for determining the time change rate of the film thickness, or may be longer than the unit time for determining the time change rate of the film thickness.

The determination unit 26 determines whether or not the time change amount of the sample is within the normal range by performing a logical operation such as determining the magnitude relationship between the value specifying the normal range and the time change amount of the sample. .. For example, when the time change amount of the sample is within the normal range, it is determined that the time change amount of the sample is within the normal range. If the time change amount of the sample is not within the normal range, it is determined that the time change amount of the sample is not within the normal range.

When the determination unit 26 determines that the time change amount of the sample is within the normal range, the determination unit 26 inputs to the storage unit 22 or the control unit 21 that no measurement abnormality has occurred due to the specific change. When the determination unit 26 determines that the time change amount of the sample is not within the normal range, the determination unit 26 inputs to the storage unit 22 or the control unit 21 that the occurrence of the measurement abnormality due to the specific change is detected. When the control unit 21 or the control device 20 receives from the storage unit 22 or the determination unit 26 that a measurement abnormality has occurred, the control unit 21 or the control device 20 executes a preset post-processing to generate a measurement abnormality due to a specific change. Output to the effect that it was detected.

Since each sample has a time index value, the determination unit 26 can specify a sample in a specific time range from the present, and can extract a sample group in the designated range. That is, the determination unit 26 can determine the measurement abnormality for each sample, aggregate the results of the determination, and calculate the abnormality rate for each sample, which is the abnormality occurrence rate per most recent time. This means that the anomaly detection sensitivity in the time domain can be set for each reference of each sample. In other words, the determination unit 26 sets a plurality of criteria, sets a normal range in the sample corresponding to each criterion, determines the measurement abnormality, and further, whether the abnormality rate per unit time is exceeded for each criterion. It is possible to perform a process of repeatedly determining whether or not to detect a measurement abnormality and then detecting a measurement abnormality. As another similar method, for example, a similar function may be realized instead of a numerical calculation method that imitates a first-order lag. In addition, the criteria of each sample described later may be weighted differently to evaluate the sum.

The control unit 21 or the control device 20 may, for example, perform a switching process of switching the sensor unit used for measurement between the first sensor unit and the second sensor unit, or a film thickness time, as a preset post-processing. Execute a hold process to hold the rate of change. That is, in the preset post-processing, when it is estimated that the specific change that occurs temporarily has subsided, the crystal is measured again using the crystal oscillator determined to be a measurement abnormality. This is a process that puts the measurement using the oscillator on standby.

The control unit 21 that executes the switching process is configured to grasp which of the first sensor unit and the second sensor unit is used for the measurement from the command to the measurement unit 23 and the detection device 14. When the occurrence of a measurement abnormality due to a specific change is detected, the control unit 21 switches to the measurement unit 23 or the detection device 14 so that the sensor unit used for the measurement is switched to another sensor unit different from the current one. Continue the measurement.

For example, in the measurement using the first sensor unit, when the occurrence of a measurement abnormality due to a specific change is detected, the control unit 21 switches the sensor unit used for the measurement to the second sensor unit, and the measurement unit 23. And the detection device 14 is allowed to continue the subsequent measurement. Then, when the occurrence of a measurement abnormality due to a specific change is detected in the measurement using the second sensor unit, the control unit 21 switches the sensor unit used for the measurement to the first sensor unit again, and the measurement unit 21. The subsequent measurements are continued by the 23 and the detection device 14.

The control unit 21 that executes the hold process assigns a time index value to the calculated time change rate of the film thickness and stores it in the storage unit 22 in the same manner as the value that can be a reference or the value that can be a sample. It is composed. The control unit 21 executes the hold process when the occurrence of the measurement abnormality due to the specific change is detected, and then releases the hold process when it is determined that the measurement abnormality due to the specific change has not occurred. ..

For example, the control unit 21 refers to the time index value immediately before the detection of the measurement abnormality as the time change rate of the current film thickness after the occurrence of the measurement abnormality due to the specific change is detected, and the time index value is set. The time change rate of the applied film thickness is output. The control unit 21 executes the hold process until the time change amount of the sample returns to the normal range, and when the time change amount of the sample returns to the normal range, the time index immediately after the time change amount is detected. With reference to the value, the time change rate of the film thickness to which the time index value is given is output. That is, the control unit 21 executes the hold process until the time change amount of the sample returns to the normal range, and releases the hold process when the time change amount of the sample returns to the normal range.

As described above, the measurement of the film thickness using the crystal oscillator is a time-series measurement when the vapor-deposited material is deposited on the crystal oscillator. Therefore, as the deposition of the vapor-filmed material in the crystal oscillator progresses, the series resonance frequency decreases according to the added mass. The measurement abnormality due to the above-mentioned specific change is that the decrease in the series resonance frequency suddenly increases and then returns in a short time.

The above-mentioned specific change occurs without changing the degree of vacuum in the film forming apparatus. On the other hand, in order to realize that the time change rate of the film thickness suddenly increases by increasing the temperature, it is necessary to suddenly increase the amount of heat of the vapor deposition source. However, the heat capacity of the vapor deposition source that digests the vapor deposition material is usually designed to be a very large value, and has a size that does not easily fluctuate at a time interval of about several minutes. That is, a sudden increase in the time change rate of the film thickness as much as 10% cannot occur by increasing the amount of heat of the vapor deposition source. From the above, the measurement abnormality due to the above-mentioned specific change is the non-uniformity of the film formation in the crystal unit due to the splash of the vapor-film deposition material, and the non-uniformity of the film formation in the crystal unit due to the impurities contained in the vapor-film deposition material. It is presumed that this is due to the non-uniformity of the film.

On the other hand, in a film forming apparatus that feedback-controls the time change rate of the film thickness to the temperature of the vapor deposition source, when a measurement abnormality occurs due to a specific change, the time change rate of the film thickness suddenly increases, and the film thickness is vapor-deposited. The output of the source is once lowered, and the time change rate of the film thickness in the film-deposited object is actually lowered. Then, the output of the vapor deposition source is increased based on the sudden return of the time change rate in the specific change, and the time change rate of the film thickness is actually vibrated.

At this time, for example, the time change rate of the film thickness is averaged or averaged so that the output of the vapor deposition source is not suddenly increased even when the time change rate of the film thickness suddenly increases. It is assumed that the value obtained by combining the obtained value, the upper limit value, and the lower limit value is feedback-controlled to the temperature of the vapor deposition source by using averaging by signal processing. According to this signal processing, the time change rate of the film thickness, which is the feedback value, can be stabilized. However, in order to stabilize the value to the extent that the above-mentioned sudden rise is suppressed, it is necessary to use a large number of samples collected in the past for averaging, and as a result, even the originally required response is achieved. It will be a big delay. In addition, even if control is stabilized by setting an upper limit value and a lower limit value for the feedback value and narrowing the width between the upper limit value and the lower limit value, under a process in which the heat flux fluctuates not a little during vapor deposition. , The width between the upper limit and the lower limit is also limited.

In the detailed analysis of the correlation between transmission and reception when the above-mentioned specific change occurs, the present inventors have set the imaginary part of admittance in the crystal oscillator 14B as a reference that does not change with time. We have found that the amount of time variation of a sample, such as the real part of admittance determined by the criterion, largely follows the specific change.

In this regard, in the case of the above-mentioned measurement abnormality detection device and measurement abnormality detection method, a candidate for a standard that does not change with time such as a phase used for admittance calculation or an imaginary part of admittance, and a real part of admittance. Candidates for specimens to be determined as a reference are sequentially stored in the storage unit 22. Then, the control device 20 sets a standard that does not change with time, and the abnormality detection unit 24 determines whether or not the amount of time change of the sample determined from the standard is within the normal range. Even in a system where the series resonance frequency continues to change with deposition, a sample determined by a time-independent criterion such as the phase for calculating admittance or the imaginary part of admittance is singular like the real part of admittance. It is a sample that follows a change. Then, such a sample has a high sensitivity to a time-changing phenomenon as compared with a series resonance frequency measured or calculated from a time-changing component and a time-free component. As a result, it is possible to detect with high accuracy a sudden increase that is estimated to return in a short time in the time change rate of the film thickness, so that the sudden increase that occurs in the time change rate of the film thickness is described above. It is possible to determine whether or not the change is specific.

<Example>
An example of detecting a measurement abnormality is shown with reference to FIGS. 4 to 7.
Using an aluminum quinolinol complex (Alq ₃ ) as a vapor deposition material, a certain amount of electric power is applied to the vapor deposition source, and the film thickness measuring device adopts the above formula (1) while keeping the heat balance per unit time in the vapor deposition source constant. , The time change rate of the film thickness during this period and others were measured. FIG. 4 shows the time change rate of the measured film thickness, that is, the temporal transition in the vapor deposition rate, together with the imaginary part of admittance. FIG. 5 shows the temporal transition of the measured film thickness in the time change rate together with the difference value in the real part of admittance, that is, the difference value in the real part of admittance. 6 and 7 are graphs showing the regions A and B, which are a part of FIG. 5, in an enlarged manner, and show the specific changes in the time change rate of the film thickness in an enlarged manner. The time change rate of the film thickness is displayed as a ratio with any one of the measured values as 1, but the unit system (for example, 0. It may be expressed as 1 nm / sec). In FIGS. 4 to 9, even if it is read as the unit system, it can be treated as synonymous.

As shown in FIG. 4, it is recognized that the vapor deposition rate in the examples decreases with the lapse of the vapor deposition time and has an inversely proportional relationship with the vapor deposition time, that is, the vapor deposition rate changes with time. rice field. In other words, it was found that the series resonance frequency changed with time so that the series resonance frequency decreased as the deposition of the vapor-filmed material in the crystal oscillator progressed. Then, it was found that the vapor deposition rate unsteadily caused a peculiar change in which the vapor deposition rate suddenly increased and then returned in a short time. Since this unsteady and specific change is observed even under the condition that the degree of vacuum, the input power, and the heat balance are constant, a phenomenon different from the physical model of the adopted mathematical formula is observed. It is assumed that it has been done.

In this embodiment, it will be described that this specific change is detected as a measurement abnormality.
In this embodiment, a reference is set for the phase or imaginary part, and then the sample is determined by the reference. As a sample, it is desirable to select a sample that can accurately detect measurement abnormalities from the data that can be used as a sample. Even when different measurement abnormalities are detected, it is possible to set a standard and to determine a sample from the standard by performing the same procedure as described below. As will be described later, the difference between the physical model and the measurement result is the main cause of the measurement abnormality, which is a specific change. Therefore, by determining an appropriate sample, it is possible to detect a wide variety of measurement abnormalities. It will also be possible to do.

As shown in FIG. 4, the imaginary part of the admittance in the measurement of the embodiment does not change like the vapor deposition rate with the passage of time, and does not follow the specific change, and changes with time. It was admitted not to. Although not illustrated and described, the phase in the measurement of the embodiment does not change with the passage of time and follows a specific change, as in the imaginary part of the admittance in the embodiment. It was found that there was no change over time. Figures 5, 6 and 7 show the results of setting a standard for the imaginary part and using the real part of admittance determined by the standard as a sample.

As shown in FIG. 5, the difference value in the real part of admittance in the embodiment, that is, the time transition in the real part of admittance is found to include a period of time that does not change with the passage of time, while the admittance It was also found that the difference value in the real part had a non-stationary change in that it suddenly increased and then returned in a short time in response to a specific change, similar to the vapor deposition rate. The difference value in the real part of admittance is the value obtained by subtracting the real part of admittance at the time of this measurement from the real part of admittance at the time of the previous measurement, and the unit time for determining the difference value is the unit for determining the deposition rate. It's the same as time. Although not illustrated and explained, the amount of time change in the real part of admittance did not show a phenomenon that responded to a specific change, and it was confirmed that it was not suitable as a sample.

As shown in FIGS. 6 and 7 in which the part of the specific change is enlarged and shown, the vapor deposition rate suddenly increases by about 5%, and after a few minutes have passed, the original vapor deposition rate is obtained. The above-mentioned specific change of returning to the value was observed. On the other hand, it was found that the difference value in the real part of admittance, that is, the amount of time change in the real part of admittance, suddenly repeatedly increased and decreased clearly at the timing when the specific change started. In other words, it was found that the amount of time change in the real part of admittance is linked to the specific change in the deposition rate.

From the above, it can be said that the amount of time change in the real part of the admittance is effective as a sample, but in order to confirm whether it can be said that the sample is linked only to specific changes, the power input to the vapor deposition source is cut off. , It was confirmed that the amount of heat balance per unit time in the vapor deposition source was intentionally changed. FIG. 8 shows the transition of the amount of time change in the real part of the admittance confirmed before and after the power cutoff.

As shown in FIG. 8, when the power supply is cut off when the time elapses 4516 minutes, the heat supply to the vapor deposition source is stopped, and the amount of heat of the vapor deposition source depends on the heat capacity of the vapor deposition source, such as a room temperature environment. It is released outside the system. That is, the temperature of the vapor deposition source changes as a typical first-order lag system, the temperature of the vapor deposition material also follows the same transition, and the deposition amount per unit time decreases rapidly according to the vapor pressure curve peculiar to the vapor deposition material. .. On the other hand, it was confirmed that the amount of time change in the real part of admittance does not reflect this. As a result, it was confirmed that the amount of change in time in the real part of admittance can be detected as a sample determined by setting a reference in the phase or the imaginary part.

In addition, assuming that the background noise of the amount of time change in the real part of the admittance when the power supply is cut off is 1 (measured value is about ± 0.05), the admittance at the time of detecting a measurement abnormality is shown in FIGS. The amount of time change in the real part is 2 times or more and 20 times or less. This indicates that it is possible to include intentionally changes in the amount of sediment in the normal range, and to consider that the outside of the normal range is a measurement abnormality due to a specific change. In other words, it is shown that using the real part of admittance as a sample is also effective in terms of signal intensity ratio. Specifically, when the background noise is set to 1, for example, when a value 1.5 times or more the background noise is observed by multiplying by a safety factor of 1.5, this is detected as a measurement abnormality. And it is sufficient. It can be said that this was able to further improve the accuracy of setting a reference for the phase, deriving a sample from the reference, and evaluating the sample with the amount of time change of the sample as a measurement abnormality. Specifically, even if the power to the vapor deposition source is changed from the maximum to the minimum, the event caused by this is not detected as an abnormality, and only the measurement abnormality can be selectively detected.

As described above, according to the above embodiment, the following effects can be obtained.
(1) The change in the amount of time change of the specimen determined by the standard that does not change with time makes it possible to detect with high accuracy a sudden increase that is estimated to return in a short time in the time change rate of the film thickness. , It is possible to accurately detect the specific change occurring in the time change rate of the film thickness.

(2) If the hold processing is performed, it is possible to output a value closer to the original value as the time change rate of the film thickness over the period in which the specific change occurs. Then, after the hold process is completed, it is possible to recalculate the original value of the time change rate of the film thickness by using the system in which the specific change has occurred.

(3) In the case where the switching process is performed, when a measurement abnormality is detected in the evaluation of the time change amount of the specimen obtained by using one sensor unit, the other sensor unit is used, thereby increasing the film thickness. It is possible to calculate the original value as the time change rate. As a result, it becomes possible to continuously and accurately calculate the time change rate of the film thickness.

(4) Since the switching process is performed between the two electrodes 14A1 and 14A2 included in the single crystal oscillator, the time change rate of the film thickness, which can be said to be the original value, is continuously maintained according to the above (3). The calculation can also be realized using a single crystal unit.

The above embodiment can also be modified and implemented as follows.
-The standard provided for the phase or imaginary part derived from the correlation is the measured value of the physical quantity used in the mathematical formula group used when calculating the time change rate of the film thickness, or the measured value of 1 or more. It may be a calculated value calculated by using, further, a range of measured values, or a range of calculated values. As the reference that does not change with time, for example, instead of the imaginary part of admittance, the imaginary part of the phase or impedance used for impedance calculation can be adopted. In the examples, an example using the formula (1) is shown, but for example, the standard may be determined by using the formula (2), and if it is a formula showing the correlation between transmission and reception, other than the above. It is also possible by using the formula of.

-The sample determined by the standard is the measured value used in the mathematical formula group used when calculating the time change rate of the film thickness, or the calculated value calculated using one or more measured values, and further. May be in the range of measured values or the range of calculated values. For the sample determined by the standard, for example, the real part of impedance can be adopted instead of the real part of admittance. In the examples, an example using the equation (1) is shown, but for example, the sample may be determined using the equation (2), and if it is an equation showing the correlation between transmission and reception, other than the above. It is also possible by using the formula of.

-The sample determined by the standard is not limited to the real part in the correlation between transmission and reception, such as the real part of admittance and the real part of impedance, and the signal intensity ratio (S /) depends on the type of measurement abnormality. It is also possible to change to the imaginary part of admittance or the imaginary part of impedance so that N ratio) can be obtained. Furthermore, it is possible to change both the real part and the imaginary part, or the magnitude of admittance and the magnitude of impedance.

-In the above embodiment, an example of detecting a measurement abnormality due to a specific change is shown based on the fact that the phase difference is in the vicinity of zero. On the other hand, the technical idea of setting a reference in the phase or imaginary part and detecting the measurement abnormality from the amount of time change of the sample determined by the reference is that the measurement abnormality other than the measurement abnormality due to the specific change described above is used. It can also be applied to detection. That is, it is assumed not only by Eq. (1) but also by Eq. (2) that a reference is set in the phase or imaginary part and the measurement abnormality is detected from the time change amount of the sample determined by the reference. It is possible to detect an event that is outside the range of the correlation between the physical model, that is, the crystal unit and the deposit. In other words, for measurement anomalies that are outside the range of correlation between the crystal unit and the deposit, a finite number of experiments were repeated in which a sample with an increased signal intensity ratio was determined from the reference, thereby achieving the above technical. It is possible to detect measurement abnormalities by applying the idea.

-The value or range in which the phase difference, which is the reference in the above embodiment, is in the vicinity of zero is the value or range of the imaginary part shown in FIG. 4, but the value or range is not limited to this, for example. It may be performed for the purpose of further improving the accuracy or detecting different measurement abnormalities by using a numerical method for further narrowing the range. For example, by performing a Fourier transform on the received signal as a numerical method and performing frequency decomposition on the received signal waveform, for example, the received signal waveform with respect to zero phase difference can be strictly specified, and this method can be applied to this waveform. Can be mentioned.
-From the viewpoint of increasing the signal intensity ratio by setting a reference for the phase, the signal intensity of the sample determined from the reference may be enhanced by using a vibration signal waveform other than a sine wave. Such a configuration makes it possible to achieve higher detection accuracy when the measurement abnormality to be identified responds selectively and strongly to a certain input frequency.

-In the embodiment, only the fundamental wave is used, but the n-fold wave of the fundamental wave is combined and used as a sample with the same phase as a reference, and a combined evaluation or a composite evaluation in which the weight is changed for each wave is performed. Is also possible. According to this configuration, it is possible to improve the detection accuracy of the measurement abnormality and to detect the measurement abnormality due to different events separately.

-The switching process is not limited to switching between electrodes in a single crystal unit, and may be applied to switching between crystal units in a configuration including a plurality of crystal units.
-Since the above-mentioned specific changes are observed even under the condition that the degree of vacuum, the input power, and the heat balance are constant, the degree of vacuum, the input power, and the heat balance are constant. The determination unit may use the condition to contribute to the improvement of the determination accuracy at the time of the logical operation of the occurrence of the abnormality, and may detect the occurrence of the measurement abnormality due to the above-mentioned specific change.

C1 ... Equivalent series capacitance Fs ... Series resonance frequency F1, F2 ... Half-value frequency Fw ... Half-value frequency width L1 ... Equivalent series inductance R1 ... Equivalent series resistance 11 ... Vacuum tank 12 ... Deposition source 14A1, 14A2, 14C ... Power supply 14B ... Crystal vibration Child 14 ... Detection device 20 ... Control device 21 ... Control unit 22 ... Storage unit 23A ... First measurement unit 23B ... Second measurement unit 24 ... Abnormality detection unit 25 ... Specific unit 26 ... Judgment unit

Claims (6)

When calculating the time change rate of the film thickness deposited on the crystal oscillator using the correlation between the transmission to the crystal oscillator and the reception from the crystal oscillator, the time change rate of the film thickness is temporarily set. It is a measurement abnormality detection device that detects the phenomenon of increase / decrease as a measurement abnormality.
A reference is set for the phase or imaginary part derived from the correlation, a sample that can follow the measurement abnormality is determined by the reference, and it is evaluated whether or not the amount of time change of the sample is due to the measurement abnormality. A measurement abnormality detection device that detects the measurement abnormality by means of. The reference is the imaginary part of admittance in the crystal unit.
The measurement abnormality detection device according to claim 1, wherein the sample is a real part of admittance in the crystal oscillator. A calculation unit that calculates the rate of change in film thickness over time,
A detection unit that makes the measurement abnormality that the amount of time change of the sample is out of the normal range,
The detection unit executes a hold process for holding the calculation result of the calculation unit immediately before detecting the measurement abnormality, and releases the hold process when the time change amount of the sample returns to the normal range. The measurement abnormality detection device according to claim 1 or 2, comprising a control unit. The first sensor unit for collecting the correlation and
Using the second sensor unit for collecting the correlation,
When the measurement abnormality is detected in the evaluation of the time change amount of the sample obtained by using one sensor unit, the time change rate of the film thickness is calculated using the correlation collected by the other sensor unit. The measurement abnormality detection device according to any one of claims 1 to 3. Two electrodes are located on the side surface of the crystal unit facing the vapor deposition source.
The first sensor unit includes one electrode and has
The measurement abnormality detection device according to claim 4, wherein the second sensor unit includes the other electrode. When calculating the time change rate of the film thickness deposited on the crystal oscillator using the correlation between the transmission to the crystal oscillator and the reception from the crystal oscillator, the time change rate of the film thickness is temporarily set. It is a measurement abnormality detection method that detects the phenomenon of increase or decrease as a measurement abnormality.
A reference is set for the phase or imaginary part derived from the correlation, a sample that can follow the measurement abnormality is determined by the reference, and it is evaluated whether or not the amount of time change of the sample is due to the measurement abnormality. A measurement abnormality detection method for detecting the measurement abnormality.

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