CN113811634B - Measurement abnormality detection device and measurement abnormality detection method - Google Patents

Abstract

The present invention relates to a measurement abnormality detection device that obtains a plurality of samples from resonance characteristic values. A plurality of samples are handled as a time-series sample group, and each sample has two or more dimensions different from each other. The measurement abnormality detection device is provided with an abnormality detection part (24), and the abnormality detection part (24) uses a detection index space represented by all dimensions of the sample, and performs a logical operation on the measurement part through the logical operation of the sample group and the detection index space. It is judged whether the obtained sample group contains samples outside the detection index space.

Description

Measurement abnormality detection device and measurement abnormality detection method

technical field

The present invention relates to a measurement abnormality detection device and a measurement abnormality detection method for detecting measurement abnormality in film thickness measurement of a deposit deposited on a crystal oscillator.

Background technique

The apparatus for performing the above film thickness measurement is mounted on a film forming apparatus such as a vacuum vapor deposition apparatus. The QCM (Quartz Crystal Microbalance) method using a film thickness measuring device is used to measure deposits based on the series resonance frequency and Half Width at Half Maximum obtained by oscillating a crystal oscillator film thickness, or it is detected that the crystal oscillator has reached the end of its product life (for example, refer to Patent Documents 1, 2, 3, and Non-Patent Document 1). The relationship between the series resonance frequency of the crystal oscillator and the film thickness is represented by, for example, the following equation (1). The relationship between the half width at half value and the film thickness of the crystal oscillator is represented by, for example, the following equation (2). In addition, 1/2 of the conductance value at the series resonance frequency is a half value, and 1/2 of the full width in the half value of a function that draws a mountain shape with the series resonance frequency as its apex is a half width. In the following formula (2), 1/2 of the full width at half-value is also described as the half-value half-width Fw. The difference ΔFw is the amount of variation in the half-width Fw, and corresponds to the amount of variation in the half-width Fw between two different film thicknesses.

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

The following formula (2) is used when using the complex elastic modulus G and the loss elastic modulus G" as the input of the system. That is, in the calculation of the complex elastic modulus G and the loss elastic modulus G", the The case where the series resonance frequency and the half-value frequency of the crystal oscillator at the time of deposition are input to the system. As the series resonance frequency, n-fold waves such as the fundamental wave and the triple wave of the fundamental wave may be used. Equation (2) is used when a relatively soft film such as an organic film is deposited on a crystal oscillator.

In addition, the difference between the structure using the formula (1) and the structure using the formula (2) is as follows: in the formula (1), only the series resonance frequency is used, so the structure in the measurement can be simplified. On the other hand, in Equation (2), since the half-value frequency is added as a variable, etc., there is a tendency that the derived input dimension increases, that is, the number of calculation steps increases, and the structure in the measurement is mainly used in Equation (1 ) is more complex in structure, but improvement in measurement accuracy can be expected. Assuming that the n-fold wave described in Patent Document 4 or the like is used, the improvement in measurement accuracy becomes more remarkable.

[mathematical formula 1]

[mathematical formula 2]

In formula (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, f _q is the series resonant frequency in the crystal oscillator when undeposited. Density ρ _f , density ρ _q , film thickness t _q , acoustic impedance ratio Z, and series resonance frequency f _q can usually be treated as constants. In Equation (1), f _c is the series resonance frequency in the crystal oscillator during deposition, and is usually a measurable value that can be used as an input value. By utilizing the input value of this variable and the above-mentioned constants, as long as the value of the series resonance frequency f _c of the variable is known, the film thickness t _f of the deposit can be calculated, in other words, such as film thickness t _f =f(series resonance frequency f _c ), it can be noted as a function of the series resonance frequency f _c .

In Equation (2), the difference ΔFw is obtained as the difference between the half width at half value Fw _q of the crystal oscillator when not deposited and the half width at half value Fw _c of the crystal oscillator during deposition. The half-value half-width Fw _c in the crystal oscillator at the time of deposition is generally a measurable value and can be used as an input value. In addition, the difference ΔFw can also be obtained using the parameters described below as shown on the right side of the formula (2). G is the complex elastic modulus, G' is the elastic modulus, G" is the loss elastic modulus. ω is the angular frequency, F ₀ is the fundamental frequency, and Z _q is the crystal shear mode acoustic impedance. The complex elastic modulus G, storage The elastic modulus G' and the loss elastic modulus G" are obtained by measuring the series resonant frequency and the half-value frequency in the crystal oscillator at the time of deposition using the method described in the conventional technical literature, and using the measurement results as input values of the variables. out. In addition, the series resonance frequency can also be obtained by combining, for example, a fundamental wave and an n-fold wave such as its triple wave. When formula (2) is used, the series resonant frequency f _c and the half-value frequency are used as input values of the variables, and the film thickness t _f of the deposit can be as film thickness t _f =f (series resonant frequency f _c , half-value frequency) That is reported as a function of the series resonant frequency f _c and the half-value frequency.

prior art literature

patent documents

Patent Document 1: Japanese Patent No. 6078694

Patent Document 2: Japanese Patent No. 2016/031138

Patent Document 3: Japanese Patent Laid-Open No. 2019-65391

Patent Document 4: Japanese Patent No. 5372263

non-patent literature

Non-Patent Document 1: Sensors and Actuators B37:(1996)111-116

Contents of the invention

The problem to be solved by the invention

In addition, if foreign matter is mixed into the deposit deposited on the crystal oscillator, or the property state of the deposit changes, the density ρ _f or the acoustic impedance ratio Z of the deposit in the above-mentioned various formulas fluctuate and become different. In particular, the state in which foreign substances are mixed into the sediment is a state in which a part of the sediment contains particles with different densities, and it is difficult to express the three-dimensional local density variation in the sediment by a single parameter, that is, the density ρ _f . However, in the film thickness measuring device using the relationship between the series resonant frequency and the film thickness, even if the density ρ _f of the deposit or the acoustic impedance ratio Z varies as described above, the density ρ _f of the deposit or the acoustic impedance ratio Z can be regarded as The calculation is performed when the ratio Z does not change. That is, the measured value obtained from the series resonance frequency is applied to the above-mentioned relational expression interpreted as the density ρ _f of the deposit and the acoustic impedance ratio Z, and is output as it is when no foreign matter is mixed into the deposit. Therefore, even in the state where the crystal oscillator needs to be replaced, the measurement abnormality caused by the above-mentioned different deposit density ρ _f or acoustic impedance ratio Z cannot be detected by the film thickness measuring device. In addition, in this specification, the abnormal range including the cases that cannot be detected by the above-mentioned conventional method is described as measurement abnormality, and the abnormality detected by the conventional method, such as product life, is only taken as an individual Exception, to explain.

An object of the present invention is to provide a measurement abnormality detection device and a measurement abnormality detection method capable of detecting measurement abnormality during film thickness measurement of a deposit deposited on a crystal oscillator.

Solution to the problem

The measurement abnormality detection device for solving the above-mentioned problems is a measurement abnormality detection device that detects measurement abnormality of a film thickness using the resonance characteristic value of a crystal oscillator, and handles a plurality of samples obtained from the above resonance characteristic value as time-series samples , and have two or more mutually different dimensions, the measurement abnormality detection device has an abnormality detection unit, and the abnormality detection unit uses the detection index space represented by the above two or more mutually different dimensions to pass the sample The logical operation with the detection index space determines whether the sample acquired by the measurement unit is outside the detection index space, and if it is determined that the sample is outside the detection index space, it is detected as a measurement abnormality.

A measurement error detection method for solving the above-mentioned problem is a measurement error detection method for detecting an abnormality in film thickness measurement using resonance characteristic values of a crystal oscillator, and includes obtaining a plurality of samples from the resonance characteristic values. The plurality of indexes described above are handled as time-series samples, and each has two or more dimensions different from each other. The measurement abnormality detection method further includes using the detection index space represented by the above two or more mutually different dimensions, and determining whether the sample obtained by the measurement unit is in the detection index space through the logical operation of the sample and the detection index space. If it is judged that the above-mentioned sample is outside the above-mentioned detection index space, it will be detected as a measurement abnormality.

According to each of the above configurations, two or more two-dimensional detection index spaces expressed by different dimensions are used, and logical operations between the samples and the detection index space are used to determine whether the plurality of samples acquired by the measurement unit include any samples outside the detection index space. samples for judgment. Then, when it is determined that a sample outside the detection index space is included, it is detected that a measurement abnormality has occurred. Thereby, even in a measurement environment in which an abnormality cannot be judged only by conventional one-dimensional indicators, it is possible to detect that an abnormality has occurred during measurement.

Film thickness may also be included in the above-mentioned film thickness measuring device.

In the above film thickness measuring device, the two or more dimensions different from each other may include at least one of equivalent series resistance and series resonance frequency.

Description of drawings

FIG. 1 is a configuration diagram showing the configuration of a measurement abnormality detection device included in one embodiment of a film thickness measurement device.

FIG. 2 is a circuit diagram showing an equivalent circuit of a crystal oscillator.

FIG. 3 is a graph showing the series resonance frequency and the half-value frequency in the conductance waveform.

FIG. 4 is a graph showing an example of the relationship between frequency and equivalent series resistance.

5 is a graph showing another example of the relationship between frequency and equivalent series resistance.

FIG. 6 is a graph showing an example of the relationship between equivalent series resistance and film thickness.

Detailed ways

Hereinafter, an embodiment of a measurement abnormality detection device and a measurement abnormality detection method will be described with reference to FIGS. 1 to 6 . In this embodiment, an example in which a film thickness measurement device including a measurement abnormality detection device is mounted on a film formation device will be described. The film thickness measuring device performs film thickness measurement and abnormal judgment of film thickness measurement. The film forming device performs feedback control and the like on the deposition rate of the film forming material based on the film thickness output from the film thickness measuring device and the judgment result.

As shown in FIG. 1 , the film forming apparatus includes a vacuum chamber 11 . The vacuum chamber 11 accommodates 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 power supply from the power source 13 to sublimate the film formation material toward the substrate (not shown). The sublimation method of 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 film-forming materials are metal compound materials such as organic materials, metal materials, metal oxides and metal nitrides. The substrate is a semiconductor substrate, a quartz substrate, a glass substrate, a resin film, or the like. The film-forming material is deposited on the substrate and the detection device 14 in the same manner.

The film thickness measurement 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 also has the function of controlling the film forming device in addition to the function of controlling the detection device 14 .

The detection device 14 includes a crystal oscillator. A crystal oscillator has a predetermined series resonance frequency as a natural frequency. The material constituting the crystal oscillator is, for example, an AT-cut crystal oscillator or an SC-cut crystal oscillator. The series resonance frequency of the crystal oscillator is, for example, not less than 3 MHz and not more than 6 MHz. The detection device 14 is used to measure the film thickness and deposition rate of the deposit deposited on the substrate. The above-mentioned measured values and calculated values such as the film thickness and deposition rate are used in the film forming device as the feedback amount of the process performed by the film forming device. The detection device 14 is arranged facing the vapor deposition source 12 in the vacuum chamber 11 . The detection device 14 outputs the detected result to the control device 20 .

The surface of the crystal oscillator is arranged to face vapor deposition source 12 . On the surface of the crystal oscillator, a film-forming material is deposited from the vapor deposition source 12 at arbitrary time intervals. The film-forming material deposited on the surface of the crystal oscillator changes the vibration frequency of the crystal oscillator as a newly added mass at arbitrary time intervals. Furthermore, the quality of the deposits on the surface of the crystal oscillator is related to the density of the deposits. That is, by measuring the change in the vibration frequency of the crystal oscillator, the film thickness, that is, the length, of the film-forming material deposited on the surface of the crystal oscillator can be obtained. Then, the film thickness measurement device vibrates the crystal oscillator, and indirectly measures the film thickness from the vibration waveform resulting from the excitation.

The film thickness measuring device uses a frequency signal, that is, an AC signal as an excitation source. The oscillated crystal oscillator responds as a system containing deposits attached to the surface. The film thickness measurement 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. The film thickness measuring device stores waveforms as detection results, and analyzes the stored waveforms. The film thickness measurement device extracts and outputs the film thickness included in the waveform analysis result.

FIG. 2 shows the system responding to excitation using an equivalent circuit. In addition, the equivalent circuit shown in FIG. 2 is also called a measurement system.

As shown in FIG. 2 , the crystal oscillator is shown as a parallel circuit in which a series resonant circuit composed of a dynamic capacitor C1 , a dynamic inductor L1 , and an equivalent series resistor R1 is connected in parallel with a shunt capacitor C0 . A series resonance circuit is an equivalent circuit including a mechanical vibrating element of a crystal oscillator. The shunt capacitor C0 is, for example, a capacitance between electrodes sandwiching the crystal oscillator including a parasitic capacitance of a package for holding the crystal oscillator. The equivalent series resistance R1 represents the loss components of vibration such as internal friction, mechanical loss, and acoustic loss when the crystal oscillator vibrates. The higher the equivalent series resistance R1 is, the harder it is for the crystal oscillator to vibrate.

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

The control device 20 supplies the power source 13 with electric power, and sublimates the film formation material from the vapor deposition source 12 toward the substrate. For example, the control device 20 uses the deposition rate obtained from the control unit 21 to perform feedback control on the output power of the power source 13 so that the deposition rate becomes a target value. When the film formation using the vapor deposition source 12 starts, the control unit 21 reads the measurement program and the measurement abnormality detection program stored in the storage unit 22, and executes the read program, thereby executing the film thickness measurement method and the measurement method. Anomaly detection method.

The control unit 21 causes the measurement unit 23 to input an AC signal to the detection device 14 . In the configuration including the first measurement unit 23A, the control unit 21 causes the first measurement unit 23A to measure the series resonance frequency Fs, for example. In the configuration including the second measurement unit 23B, the control unit 21 scans the frequency of the AC signal around the series resonance frequency Fs of the crystal oscillator, so that the second measurement unit 23B measures the series resonance frequency Fs, half-value frequencies F1, F2 and half-value bandwidth.

The control unit 21 causes the storage unit 22 to store the vibration waveform to which the detection device 14 responds. The control unit 21 causes the storage unit 22 to store various values processed by the measurement unit 23 and the abnormality detection unit 24 . The control unit 21 analyzes the vibration waveform, or causes the measurement unit 23 to analyze the vibration waveform. The control unit 21 causes the measurement unit 23 to calculate the film thickness at predetermined time intervals, that is, the deposition rate. Then, the control unit 21 causes the abnormality detection unit 24 to process various values input from the measurement unit 23 .

When the control unit 21 receives a message that the film formation has been completed from the control device 20 , it terminates the execution of the measurement program.

The control unit 21 is constituted by, for example, hardware and software for a computer such as a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory). The control unit is not limited to performing all kinds of processing by software. For example, the control unit may include a judgment-oriented integrated circuit (ASIC) as dedicated hardware for executing at least a part of various types of processing. The control unit may be configured as a circuit including one or more dedicated hardware circuits such as ASIC, one or more microcomputers as processors operating in accordance with software as a computer program, or a combination thereof.

The storage unit 22 stores various values such as target value, index, detection index space, sample, voltage vibration waveform, excitation frequency range, excitation signal waveform, film thickness measurement program, measurement abnormality detection program, and data. The control unit 21 reads various values, film thickness measurement programs, and data stored in the storage unit 22 , and executes the film thickness measurement program to cause the measurement unit 23 to execute various processes. The control unit 21 executes various processes. The various values, measurement abnormality detection program and data stored in the storage unit 22 are read, and the measurement abnormality detection program is executed to cause the abnormality detection unit 24 to execute various processes including determination of measurement abnormality.

The first measurement unit 23A is configured to be able to measure, for example, the series resonance frequency Fs of a crystal oscillator, which is an example of a resonance characteristic value, in cooperation with the storage unit 22 and the control unit 21 . The first measurement unit 23A includes, for example, an oscillation circuit and a measurement circuit. The oscillating circuit uses an AC signal as an excitation signal, and inputs a specific frequency such as the series resonance frequency Fs of the crystal oscillator when not deposited or a frequency near it to the crystal oscillator included in the detection device 14 to vibrate the crystal oscillator. The measurement circuit measures, for example, a voltage vibration waveform as a damping response after the excitation is stopped, and records the result in the storage unit 22 . The control unit 21 calculates a required resonance characteristic value using a known analysis method prepared in advance for the recorded voltage vibration waveform. An example of an analysis method is a method using exponential function decay (hereinafter also referred to as Ring-down analysis). Ring-down analysis utilizes an analytical method in which the fluctuating mass attached to the surface of the crystal oscillator can be observed as a kinetic energy release fluctuation during the decay response.

The second measurement unit 23B functions as a so-called network analyzer. The second measurement unit 23B is configured to be able to measure the series resonance frequency Fs, the half-value frequencies F1 , F2 , and the like without cooperating with the storage unit 22 and the control unit 21 . The second measurement unit 23B is configured to include a signal supply circuit and a measurement circuit, and is configured to remove the excitation signal supplied to the crystal oscillator from a voltage oscillation waveform as a response superimposed on the excitation signal, and separate only the response signal. For example, the signal supply circuit inputs an AC signal as an excitation signal to a crystal oscillator included in the detection device 14 . As the excitation signal, for example, a sine wave sweep signal near the series resonance frequency Fs of the crystal oscillator is used. The measurement circuit obtains, for example, the series resonance frequency Fs, the half-value frequencies F1 and F2, and the half-value half-width Fw from the response signal. The above-mentioned series resonance frequency Fs, half-value frequencies F1, F2, and half-value half-width Fw are examples of resonance characteristic values.

In this way, when the measurement unit 23 is configured to include the first measurement unit 23A or the second measurement unit 23B, it is possible to obtain a function for deriving the film thickness, that is, an input value of a variable in Equation (1) or Equation (2). The control unit 21 may be configured to select either one of the first measurement unit 23A and the second measurement unit 23B based on the measurement result. In addition, the measurement unit 23 may be configured to calculate variables other than the variables described in Formula (1) to Formula (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 bandwidth is twice the half-value half-width Fw, and is the difference between one half-value frequency F1 and the other half-value frequency F2. In other words, the half-value half-width Fw is 1/2 of the half-value bandwidth.

However, the Q value and D value which are indicators of the accuracy and stability of the oscillation frequency in the crystal oscillator are represented by the following equations (3) and (4). When the equivalent series capacitance C1 can be treated as a constant without changing, the dynamic inductance L1 is expressed by the following equation (5) using the series resonance frequency Fs, and the equivalent series resistance R1 is expressed by the following equation (6). These expressions are stored in the storage unit 22 . The control unit 21 calculates various values using the above formulas. For example, the control unit 21 performs calculation based on the above formula in time series every time the half-value frequencies F1 and F2 and the series resonance frequency Fs are obtained in the measurement unit 23 . The calculation performed by the control unit 21 may also be performed by the abnormality detection unit 24 . Calculated values, which are calculation results performed in time series, are stored in the storage unit 22 after being given time index values in time series. The same time index value is assigned to the results obtained by calculation using the half-value frequencies F1 and F2 and the series resonance frequency Fs obtained at the same time in the measurement unit 23 . The provision of the time index value is performed by any one of the measurement unit 23 , the control unit 21 , and the abnormality detection unit 24 .

Q=Fs/(2×Fw)…Formula (3)

D=1/Q...Formula (4)

L1＝1/((2π×Fs) ² ×C1)…Formula (5)

R1=4π×L1×Fw…Formula (6)

The measurement unit 23 repeatedly executes the processing including the measurement and analysis of the resonance characteristic value described above at predetermined time intervals, and transmits the measured value and the calculated value to the storage unit 22 . The measurement time interval may be fixed to the shortest time within a processable range in terms of accuracy, but may be variable including a temporary interruption of the control device 20 or the control unit 21 . Since the above-mentioned time variation is recorded in the storage unit 22 as a relative relationship of time index values, it can also be used in subsequent numerical processing such as calculation processing of the deposition rate for each predetermined time.

Returning to FIG. 1 , the abnormality detection unit 24 is configured to be able to use signals used for measurement and analysis by the measurement unit 23 and measured values and calculated values stored in the storage unit 22 . Examples of measured values and calculated values stored in the storage unit 22 include time response waveforms of excitation and response, that is, voltage vibration waveforms, half-value frequencies F1, F2, series resonant frequency Fs, conductance value at resonant frequency, equivalent series Resistance R1, film thickness, etc. In addition, the index value for specifying the detection index space is a value determined experimentally in advance for determining the presence or absence of a measurement abnormality, and is manually input into the storage unit 22 via the control device 20 , for example.

The abnormality detection unit 24 is configured to process a combination of two or more values assigned to the same time index value as a sample. In other words, multiple samples become spreadsheet-like data with time index values. In addition, when processing a sample, the measurement unit and the control unit 21 may create a plurality of samples, that is, a sample group, store the sample group in the storage unit 22 , and make the sample group available to the abnormality detection unit 24 .

Hereinafter, an overview of detection of measurement abnormality performed by the abnormality detection unit 24 will be described. In the following description, the abnormality detection unit 24 includes a specification unit 25 and a detection unit 26 .

First, the abnormality detection unit 24 sets a detection index space based on the index value stored in the storage unit 22 in a preparatory process. The index value is a value specifying a normal range in the dimension of the detection index space. The detection index space is a space indicating a normal range during measurement, and is a space having a region of two or more dimensions. In addition, in the present embodiment, each dimension of the detection index space is set to correspond to each physical quantity. There is a one-to-one correspondence between the dimension and the physical quantity, and the dimension can also be replaced by the corresponding physical quantity. Next, in the preparatory process, the abnormality detecting unit 24 selects each physical quantity so as to become a value corresponding to the dimension of the setting detection index space, with respect to the measured value measured by the measuring unit 23 or the measured value and calculated value stored in the storage unit 22. .

The abnormality detection unit 24 acquires the value of the selected physical quantity, which is the physical quantity selected in the work process, in accordance with the processing command from the control unit 21 . Acquisition of the value of the selected physical quantity is a sequential process synchronized with the process of the measurement unit 23, or a process asynchronous with the process of the measurement unit 23 when a time index value is assigned to the value of the selected physical quantity. In addition, below, the case of sequential processing is demonstrated. The value of the selected physical quantity acquired by the abnormality detection part 24 is handled as a sample. Samples are indexed using the time index value. By using the index, for example, the amount of change per unit time between arbitrary samples can be calculated. In the above, an example in which the value acquired by the abnormality detection unit 24 is a selected physical quantity is shown, but as described later, the value acquired by the abnormality detection unit 24 may be various values such as dimensionless.

The abnormality detection unit 24 is configured to display samples as points in the same space as the detection index space. In addition, in the present embodiment, the abnormality detection unit 24 is configured to display the detection index space and the sample on the same two-dimensional plane. For example, the abnormality detection unit 24 causes the determination unit 25 to execute the above-mentioned operation. The specifying unit 25 specifies a point displayed by the sample on the two-dimensional plane, and then judges whether or not the sample is outside the detection index space. For example, with regard to each coordinate value of the sample in the two-dimensional plane, by performing logical operations such as judging the size relationship with each index value that determines the normal range, it is judged whether it is within the normal range displayed by the detection index space . In the present embodiment, the determination unit 25 determines the detection index space as a closed two-dimensional plane, and when the coordinates of the sample exist in the normal range, it is judged as normal, and when the coordinates of the sample do not exist in the normal range, It was judged that the measurement was abnormal.

When determining that the measurement is abnormal, the specifying unit 25 inputs, for example, to the storage unit 22 that a measurement abnormality has been detected. When the detection unit 26 receives a message that a measurement abnormality has occurred from the storage unit 22 or the identification unit 25, it performs necessary processing and then outputs an output indicating that the measurement abnormality has been detected. When the control unit 21 or the control device 20 receives an output indicating that a measurement abnormality has occurred, for example, an operation for replacing a crystal oscillator or an operation for stopping the film forming apparatus is started. In addition, the necessary processing performed by the detection unit 26 is processing related to the time domain, for example, signal processing representing a noise reduction method. As an example, a process of detecting a measurement abnormality after a plurality of abnormality judgments is given. However, in particular, if the processing regarding the time zone is unnecessary, the result determined by the specifying unit 25 may be output immediately. In the above configuration, the detection unit 26 may also be omitted.

When the abnormality detecting unit 24 judges that the measurement is normal, the control unit 21 instructs the execution again after a preset time interval to obtain the value of the selected physical quantity and make the abnormality detecting unit 24 judge. Usually, this process is repeated until the control device 20 of the film forming apparatus finishes film forming.

In addition, the value of the sample is typically a physical quantity constituting the terms of the formulas (1) to (6), but the formulas (1) to (6) may be changed so that the terms are dimensionless. At this time, the dimensional value of the detection index space is set, that is, the index value stored in the storage unit 22 is also a dimensionless quantity. Even in the structure using the above-mentioned dimensionless quantity, the same result can be obtained by judging whether or not a sample exists in the detection index space. In addition, the number of dimensions constituting the sample may be more than the dimension constituting the detection index space. In this embodiment, as shown in FIG. 4 and FIG. 5 , the combination of the series resonance frequency Fs (MHz) and the equivalent series resistance R1 (Ω), the film thickness (μm) and the equivalent series resistance R1 (Ω) Groups are utilized as two-dimensional samples. In addition, if there is a correlation between two physical quantities, physical quantities that do not exist in the above formulas (1) to (6) may be used. For example, the current flowing through the entire equivalent circuit shown in FIG. 2 and the current flowing through the shunt capacitor C0 may be included in the dimensions constituting the sample.

Since a plurality of samples have time index values, the abnormality detection unit 24 can specify samples in a specific time range from now, and can extract a sample group in the specified range. That is to say, the abnormality detection unit 24 can judge each sample, collect the judgment results, and calculate the latest abnormal occurrence rate per hour, that is, the abnormality rate in dimensional units. This means that the anomaly detection sensitivity in the time zone can be set for each dimension. In other words, the abnormality detection unit 24 performs the following process: setting an index within a normal range for each physical quantity, performing abnormality judgment, further repeatedly judging whether the abnormality rate per unit time exceeds a predetermined value for each physical quantity, and then measuring whether the abnormality is abnormal. detection. As another similar method, for example, a numerical calculation method imitating one lag can also be used instead, and the same function can also be realized.

An example of detection of abnormality in measurement using two dimensions will be described with reference to FIG. 4 . In addition, in FIG. 4 and FIG. 5, the sample which judged beforehand as a normal case and a membrane quality abnormal case by the experiment performed beforehand is shown.

The measurement of the film thickness refers to the time-series measurement when depositing the film-forming material on the crystal oscillator. Therefore, as the deposition of the film-forming material on the crystal oscillator proceeds, the series resonance frequency Fs decreases according to the added mass, and the state shifts toward the left end of the frequency axis. That is, the right end of the frequency axis in FIG. 4 represents a state in which no film-forming material is deposited on the crystal oscillator and the film thickness is zero. Then, the crystal oscillator when the film thickness is zero is shown to resonate in series at 5 MHz.

<First embodiment>

In the example shown in FIG. 4, a first embodiment in which the deposit is gold is included. The abnormality detection unit 24 sets 5 MHz or less and 4.2 MHz or more as a first detection index corresponding to the series resonance frequency Fs as one dimension. In addition, the abnormality detection unit 24 sets 20Ω to 50Ω as the second detection index corresponding to the equivalent series resistance R1 which is another dimension. The above two indicators are 4 sets of coordinate points, which limit the detection indicator space delimiting the rectangular plane. In addition, the first detection index may be greater than 4.2 MHz, and this structure is suitable for cases where an abnormality judgment does not need to be performed on the upper limit of the first detection index by using a checked crystal oscillator or the like.

Here, in the prior art such as Patent Document 3, for example, when the series resonance frequency Fs is lower than 4.2 MHz, it is set that the usable period of the crystal oscillator ends due to deposition, that is, it is determined that the crystal oscillator has reached the end of use. life. That is, when the series resonance frequency Fs obtained by analyzing the vibration waveform is lower than 4.2 MHz, it is determined that an individual abnormality has occurred. For the detection of individual abnormalities, only one dimension of series resonance frequency Fs is selected, and the detection index under the selected dimension is set to be below 5MHz and above 4.2MHz, and the linear range and index value within the set range If it is within this range, it will be judged as normal, and if it is outside this range, it will be judged as individual abnormality. In other words, the detection of an individual abnormality can be said to be detection using only the samples of the series resonance frequency Fs and the magnitude relationship of the index value. In this case, it is also applicable to a noise reduction method in which the index value has multiple steps, or the abnormality rate per hour of the sample group is used as described in Patent Document 3.

In this regard, in the first embodiment, two types of indexes, the first detection index and the second detection index, are used for judgment. That is, a two-dimensional detection index space surrounded by a rectangle is used for determination. The specifying unit 25 judges whether or not each sample is located in a plane serving as a detection index space by logical operation, and assigns a normal or abnormal status indicating the judgment result to each sample.

In addition, the process of assigning the state is a sequential process acquired in time series of samples. The spatial shape represented by the detection index space is not limited to a rectangular shape, and may be set in a triangular shape or an irregular shape according to the selected detection index or index value. For example, as the second detection index corresponding to the equivalent series resistance R1, it is set at 20 Ω or more and 50 Ω at 5 MHz, and at 4.2 MHz, it is set at 30 Ω or more and 80 Ω or less. The tendency to change proportionally in one direction corresponds to a trapezoidal detection index space. In this way, the best detection sensitivity can be maintained even in any deposition state. In this embodiment, the results determined by the determination unit 25 are sequentially output via the detection unit 26 .

As described above, if a configuration in which a detection index space of two or more dimensions is used, it is possible to detect measurement abnormalities in multiple dimensions. As in the conventional example, in the configuration in which only the one-dimensional detection index space of the series resonance frequency Fs is set, it is impossible to detect the result of only the variation of the equivalent series resistance R1 shown in FIG. Abnormal measurement. Even if the abnormal rate per hour is used for the series resonance frequency, the abnormality of the film quality shown in FIG. 4 displayed between 4.4 MHz and 4.5 MHz cannot be detected as a measurement abnormality, and it is even measured as a normal measurement. This is because the variation in the equivalent series resistance R1 is not related to the variation in the time domain of the series resonance frequency Fs. On the other hand, by using a configuration of a two-dimensional detection index space using the range of the equivalent series resistance R1 in addition to the series frequency range, it is possible to detect a sample with abnormal film quality as shown in FIG. 4 as a measurement abnormality. In addition, the physical quantity used as an index for judging abnormality in measurement can be appropriately selected according to requirements such as sensitivity to be judged as abnormal in measurement, for example, abnormality in film quality, etc., according to abnormality in measurement that occurs.

<Second embodiment>

In the example shown in FIG. 4, the second embodiment in which the deposit is aluminum is included. In the second embodiment, instead of the detection index space described in the first embodiment, a two-dimensional detection index space having a polygonal boundary imitating a curve or a two-dimensional detection index space having a curved boundary is set. Same detection as in the first embodiment. Hereinafter, a detection index space different from that of the first embodiment will be described.

In the first embodiment, the first detection index and the second detection index are set as a maximum of 4 sets of coordinate points, and in the second embodiment in which a polygonal boundary imitating a curve or a curved boundary is set, as the first Three or more values are set for the detection index, and more than four sets of coordinate points are designated as the detection index space. Hereinafter, the first detection index that sets a polygonal boundary imitating a curve or a curved boundary is also referred to as a curved index.

Hereinafter, a calculation method of the curve-shaped index will be described.

For example, using storage elastic modulus G', which is a physical parameter of aluminum, of 26 GPa and loss elastic modulus G" of aluminum of 0.2 GPa, an index function expressed as equivalent series resistance R1 = f (series resonance frequency) is derived in advance When deriving the index function, use the above-mentioned formula etc.. The control device 20 uses the above-mentioned index function to scan in the range of the first detection index, that is, below 5MHz and above 4.2MHz, and calculate the equivalent series resistance value in each frequency The dotted line shown in Fig. 4 represents the coordinate trajectory when scanning the range of the first detection index.

Since the dotted lines shown in FIG. 4 are calculated values based on physical parameters, in the control device 20, for example, the allowable range of fluctuation is set to ±10% of the calculated value. That is to say, 1.1 times of the value represented by the dotted line in Fig. 4 is a curvilinear index representing the upper limit of the first detection index, and 0.9 times of the value represented by the dotted line in Fig. 4 is a curvilinear index representing the lower limit of the first detection index index.

In addition, in the second embodiment, the detection index is defined by the multiple of the scalar value for the dimension of the equivalent series resistance, but the perturbation direction of the dotted line that allows fluctuation includes the dimension on the side of the series resonance frequency, that is, Can. That is, it is also possible to define the perturbation amount with a vector value. In this way, even when the tendency of fluctuation spans two dimensions, it is possible to more accurately detect measurement abnormalities. In addition, since various experiments are not required to set the detection index space, the work for setting the detection index space can be simplified. In addition, if the previously carried out experimental results are combined with the above-mentioned calculated values, the perturbation amount becomes clear, and the accuracy of determination of measurement abnormality can be further improved.

In addition, even by detection set in a detection index space having a boundary indicated by a curved index, a sample example of abnormal membrane quality shown in FIG. 4 can be detected as a measurement abnormality. For example, as in the conventional example, in the following configuration, that is, in the configuration in which only the one-dimensional detection index space of the equivalent series resistance R1 is set, and the one-dimensional detection index space is 20Ω to 700Ω, the graph cannot be Samples with abnormal membrane quality shown in 4 were detected as measurement abnormalities. Even if the range where the equivalent series resistance R1 is 50Ω or less is set as the detection index space, although a sample with an abnormal film quality with an equivalent series resistance R1 of 100Ω can be detected as a measurement abnormality, the series resonance A normal sample with a frequency Fs of 4.6 MHz or less was detected as a measurement abnormality. As a result, the lifetime of the crystal oscillator, that is, the usable period, is greatly shortened. In this regard, in the structure using the detection index space with the boundary represented by the curved index, in other words, using the detection index space with the curved boundary, even if the deposit is an aluminum film, it is possible to clearly distinguish the normal samples and abnormal samples.

<Third embodiment>

In the third embodiment, the following region is described as the range of the first detection index, that is, the region where the loss elastic modulus G" can be ignored, that is, even if the film-forming material is deposited on the crystal oscillator, the complex elastic modulus Quantity G, storage elastic modulus G', and loss elastic modulus G" are almost unchanged from the intrinsic value of the crystal oscillator. In the third embodiment, an index function expressed as equivalent series resistance R1 = f (series resonance frequency) is derived by using the density ρ _f of the deposit as the value of the organic substance which is the film-forming material.

The control device 20 scans the range of the first detection index using the above index function, and calculates the value of the equivalent series resistance at each frequency. The straight line shown in FIG. 5 represents the coordinate locus when scanning is performed in the first detection index range. The control device 20 perturbs the straight line shown in FIG. 5 in the same manner as in the second embodiment, and sets a rectangular detection index space by combining it with the first detection index. Then, the control device 20 detects a measurement abnormality using the detection index space thus set.

In addition, in the configuration in which the detection index space is set according to the density ρ _f of the deposit, the density ρ _f of the deposit can also be changed to gold or aluminum. That is, it can also be changed so that a two-dimensional detection index space is selected from the density ρ _f of the deposit. That is, in other words, the selection of the detection index space can also be based on the three-dimensional detection index space using the three indexes of the density ρ _f of the deposit, the equivalent series resistance R1 and the series resonance frequency Fs, to select the corresponding to the type of sediment. Two-dimensional detection indicator space. In this way, the detection index space is not limited to two dimensions, and can be suitably used in spaces of three or more dimensions.

<Fourth embodiment>

In the fourth example, the dimension used as the detection index space in the second example is changed from the series resonance frequency Fs to the film thickness. Then, in the fourth embodiment, measurement abnormality is detected using a two-dimensional detection index space having a polygonal boundary imitating a curve similar to that of the second embodiment or a two-dimensional detection index space having a curved boundary.

First, an index function expressed as equivalent series resistance=f (film thickness) is derived. In the derivation of the index function, the same conditions as in the second embodiment are used. That is, a function corresponding to a change in the deposited amount of aluminum and a change in the equivalent series resistance R1 is derived as an index function. The control device 20 scans the range of the film thickness, which is the range of the first detection index, using the above-mentioned index function, and calculates the value of the equivalent series resistance in each film thickness. The dotted line shown in Fig. 6 represents the coordinate trajectory when scanning with the index function. Next, the control device 20 sets a first detection index. The first detection index can be calculated from a previously performed experiment, but under the same conditions as in the second embodiment, the first detection index is 0 μm or more and 60 μm or less. The range of the above-mentioned film thickness is a value corresponding to 5 MHz or less and 4.2 MHz or more of the first detection index of the second embodiment. Next, the control device 20 sets a detection index space that perturbs the dotted line in FIG. 6 . Thereafter, the procedure for detecting measurement abnormality is the same as that of the second embodiment.

That is to say, compared with the second embodiment, the first detection index and the second detection index are substantially the same in the fourth embodiment, and the difference between the fourth embodiment and the second embodiment is that the dimensions constituting the detection index space are One-dimensional. Specifically, the series resonance frequency Fs constituting the detection index space of the second embodiment is replaced by the film thickness in the fourth embodiment. Then, since the detection index space in the fourth embodiment is a case where aluminum is used as a physical parameter, it can be used when the deposit is aluminum.

Here, as shown by the dotted line in FIG. 6, in the space where the film thickness and the equivalent series resistance are taken as dimensions, a normal sample with aluminum as a deposit and a sample with an abnormal film quality are shown. In addition, A normal sample with silver and tris(8-quinolinolato)aluminum (Alq ₃ ) as deposits is also shown. In this example, a normal sample is considered to be 0 μm or more and 20 μm or less in the first detection index, and to exist in the same range as in the first embodiment in the second detection index. Then, the coordinate values of samples considered to be abnormal in membrane quality are far from the second detection index.

In this way, regarding the perturbation in the fourth embodiment, as long as it satisfies the above-mentioned method, although the detection index space using aluminum is used as the physical parameter, as long as it is a judgment using the above-mentioned detection index space, for gold, silver, Tris(8-quinolinolato)aluminum (Alq3), which is an organic substance, can also detect measurement abnormalities. In addition, since measurement abnormalities can be detected for deposits having different densities, measurement abnormalities can be determined without increasing the number of calculation steps of the control device 20 .

As mentioned above, according to the said embodiment, the following effects can be acquired.

(1) Since abnormality determination using a detection index space of two or more dimensions is performed, it is possible to detect a measurement abnormality that cannot be detected by a one-dimensional detection index.

(2) In the structure that includes the film thickness in the dimension constituting the detection index space, it is possible to judge whether the deposit is a relatively hard film or the deposit is a relatively soft film. .

(3) Since the equivalent series resistance R1 and the series resonance frequency Fs are dimensions that respond strongly to changes in the mass of deposits deposited on the crystal oscillator, respectively, at least the series resonance frequency Fs and the equivalent series resistance R1 are included In the case of one detection index space, it can also be regarded as suitable for detection of measurement abnormality depending on mass change.

(4) Whether the internal friction and the complex modulus of elasticity contribute to the equivalent series resistance R1 of a relatively soft film is the measurement object, or the internal friction and the complex modulus of elasticity do not contribute to the equivalent series resistance R1 In the case of a relatively stiff film, the density ρ _f is a dimension that responds directly to changes in the mass of the deposit deposited on the crystal oscillator. Therefore, even in the case of using the structure including the three-dimensional detection index of the density ρ _f , it can be considered that it is particularly suitable for detecting the occurrence of measurement abnormality depending on the mass change.

(5) In the case of a structure that includes the density of the film in the dimensions constituting the detection index space, whether the deposit is a relatively hard film or the deposit is a relatively soft film, the It can be applied to the common detection index space mentioned above.

(6) In the case of a structure in which the series resonance frequency Fs and the half-value frequencies F1 and F2 are used as the resonance characteristic value for obtaining the sample group, since the above-mentioned formula 2 can be used, the same as the case of using only the above-mentioned formula 1 Compared with this method, it is also possible to expand the range of dimensions used to express the detection index.

＜Other Examples＞

The dimensions constituting the detection index space can also be series resonant frequency Fs and equivalent series resistance R1, or D value, D value and equivalent series resistance R1 obtained from series resonant frequency Fs and half-value bandwidth. In addition, the dimension used to express the detection index may be selected from the group consisting of series resonance frequency Fs, equivalent series resistance R1, Q value, half-value half-width, film thickness, and current value flowing into the crystal oscillator. above value. For example, the first detection index value may be one value in the group consisting of series resonance frequency Fs, equivalent series resistance R1, Q value, half-value half-width, film thickness, and current value flowing into a crystal oscillator. The second detection index value is one type of value other than the first detection index value in the same group. In this case, from the viewpoint of improving the detection accuracy of measurement abnormality, it is desirable to select a group of variables whose second detection index value greatly changes from the first detection index value.

In addition, for example, as a countermeasure against noise, the detection unit 26 adds a time delay element to detect a measurement abnormality. An example of adding a time delay element is to add a so-called primary delay element when judging the status of sequential processing in time series. Specifically, the detection unit 26 determines that a measurement abnormality has occurred when the detection unit 26 receives a predetermined number of samples in a state indicating that the sample is abnormal every arbitrary time. In addition, when it is desired to increase the temporal detection sensitivity of the selected index, the detection process as an immediate judgment may be performed without adding the above-mentioned primary delay element or the like to the dimensional direction of the index. That is, the technical idea of the present invention can also be implemented as an appropriate noise countermeasure in each dimension.

Symbol Description

C1: dynamic capacitance

Fs: series resonant frequency

F1, F2: half value frequency

Fw: Half value frequency width

L1: dynamic inductance

R1: equivalent series resistance

11: Vacuum tank

12: Evaporation source

13: Power supply

14: Detection device

20: Control device

21: Control Department

22: Storage department

23: Measurement department

23A: The first measurement department

23B: The second measuring department

24:Anomaly Detection Department

25: Determine the Ministry

26: Detection Department.

Claims (2)

1. A measurement abnormality detection device, wherein,

the measurement abnormality of the film thickness is detected using the resonance characteristic value of the crystal oscillator,

a plurality of samples obtained from the resonance characteristic value are processed as samples having a time series and respectively have 2 or more dimensions different from each other,

the measurement abnormality detection device includes an abnormality detection unit that determines whether or not the sample acquired by the measurement unit is outside the detection index space by a logical operation between the sample and the detection index space using a detection index space represented by the 2 or more different dimensions, and detects the measurement abnormality if the sample is determined to be outside the detection index space,

in the measurement abnormality detection device, an equivalent circuit of the crystal oscillator is used as a measurement system, the equivalent circuit is shown as a parallel circuit in which a series resonance circuit including a mechanical oscillation element of the crystal oscillator and a shunt capacitor as a capacitance between electrodes of the crystal oscillator are connected in parallel, the series resonance circuit being composed of a dynamic capacitance, a dynamic inductance, and an equivalent series resistance,

the 2 or more mutually different dimensions include at least 2 of a series resonance frequency, an equivalent series resistance, and a film thickness of a film-forming material deposited on the crystal oscillator,

the detection index space has a polygonal shape boundary defined by values of indexes that determine a normal range of each of the dimensions.

2. A method for detecting abnormality in measurement, wherein,

the measurement abnormality of the film thickness is detected using the resonance characteristic value of the crystal oscillator,

the assay abnormality detection method includes:

obtaining a plurality of samples, wherein a plurality of samples are obtained according to the resonance characteristic value, and the plurality of samples are treated as samples having a time series, and the plurality of samples respectively have more than 2 dimensions different from each other; and

using a detection index space represented by the 2 or more different dimensions, determining whether or not the sample obtained by the measurement section is outside the detection index space by a logical operation of the sample and the detection index space, and if it is determined that the sample is outside the detection index space, detecting that the measurement is abnormal,

in the measurement abnormality detection device, an equivalent circuit of the crystal oscillator is used as a measurement system, the equivalent circuit is shown as a parallel circuit in which a series resonance circuit including a mechanical oscillation element of the crystal oscillator and a shunt capacitor as a capacitance between electrodes of the crystal oscillator are connected in parallel, the series resonance circuit being composed of a dynamic capacitance, a dynamic inductance, and an equivalent series resistance,

the 2 or more mutually different dimensions include at least 2 of a series resonance frequency, an equivalent series resistance, and a film thickness of a film-forming material deposited on the crystal oscillator,

the detection index space has a polygonal shape boundary specified by a value of an index that determines a normal range of each of the dimensions.

Images