JP2018059201A - Film thickness monitoring device, film deposition device, and film thickness monitoring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film thickness monitoring device, a film deposition device, and a film thickness monitoring method capable of precisely monitoring the thickness of a film formed in an object.SOLUTION: A film thickness monitoring device 10 comprises: an output part 17 for outputting a measurement signal having a frequency varied within a predetermined range, to a piezoelectric element; a receiving part 18 for receiving the measurement signal and a reflection signal reflected from the measurement signal by the piezoelectric element; and a monitoring part 19 for determining the frequency characteristics of the impedance and the frequency characteristics of a phase thereby to determine the resonance frequency of the piezoelectric element on the basis of the received measurement signal and reflection signal, and for monitoring the thickness of the film formed on the filming object on the basis of the amount of change of the resonance frequency determined.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a film thickness monitoring apparatus, a film forming apparatus, and a film thickness monitoring method.

  A film forming process such as vacuum evaporation or sputtering is performed while monitoring whether the film thickness of the film deposited on the surface of the film formation target matches a preset film thickness. As one of the methods for monitoring the film thickness, a monitoring method called a crystal oscillation type film thickness monitoring method is used. In the crystal oscillation type film thickness monitoring method, a crystal resonator is disposed in a film forming chamber where a film formation target is disposed, and the crystal resonator is connected to an oscillator to oscillate. This is a method of converting to a film thickness. This is a monitoring method using the phenomenon that the resonance frequency of the crystal resonator decreases when the film forming material adheres to the surface of the crystal resonator.

  The crystal oscillation type film thickness monitoring method is applied to, for example, a film forming apparatus described in Patent Document 1. As shown in FIG. 4 of Patent Document 1, the film forming apparatus includes an evaporation source 2 disposed at the bottom of the vacuum chamber 1, a substrate that is a film formation target, and a sensor 4 that houses a crystal resonator 3. Is composed of. Then, the change in the natural frequency of the crystal unit 3 is measured to calculate the film thickness and the film formation rate.

Japanese Patent Laid-Open No. 11-160057

  The crystal oscillation type film thickness monitoring method has a problem that an oscillation phenomenon due to a sub-vibration called frequency jump occurs because the crystal resonator is oscillated using an oscillator. Usually, the quartz oscillator is manufactured so that the level of the secondary vibration becomes sufficiently small with respect to the main vibration, but if the load mass of the crystal oscillator increases due to the deposition of the film forming material, the secondary vibration becomes strong, The frequency jumps to oscillation due to the secondary vibration, and the resonance frequency being monitored fluctuates discontinuously. When a frequency jump occurs, the amount of change in the resonance frequency of the main vibration cannot be detected, so that the film thickness monitoring accuracy decreases, leading to the generation of defective products and a decrease in production efficiency.

  In addition, the crystal oscillation type film thickness monitoring method remarkably deteriorates the film thickness measurement accuracy when the oscillation of the crystal resonator becomes unstable. It is necessary to replace the crystal resonator as the lifetime of the sensor for monitoring the thickness of the resonator is reached. In addition, since the resonance frequency is detected by oscillating the crystal resonator, the film thickness measurement becomes impossible when the oscillation stops.

  Further, since the crystal oscillation type film thickness monitoring method controls the film formation rate based only on the oscillation frequency of the crystal resonator, the secondary vibration cannot be determined, and the film formation rate may become unstable. Moreover, since the fluctuation of the resonance frequency caused by the secondary vibration is fed back to the film formation rate control as it is, unnecessary power adjustment of the vapor deposition source or the like occurs. For example, when control is performed to keep the film formation rate constant, the actual film formation rate is unstablely disturbed due to the secondary vibration. In addition, the life of the crystal unit as a sensor is short, and the crystal unit must be frequently replaced.

  The present invention has been made in view of the above circumstances, and by detecting the frequency characteristics of a piezoelectric element without using an oscillator, the influence of sub-vibration is removed, and the film thickness that is formed on the film formation target. An object of the present invention is to provide a film thickness monitoring apparatus, a film forming apparatus, and a film thickness monitoring method capable of monitoring the above with high accuracy. In addition, by monitoring characteristics other than the resonance frequency, a desired film formation rate can be stably maintained. Furthermore, the life of the piezoelectric element used in the film thickness monitoring device can be extended.

The film thickness monitoring apparatus according to the first aspect of the present invention is:
Using a piezoelectric element disposed in the same film formation chamber as the film formation target disposed in the film formation chamber, the film thickness of the film formed on the film formation target that has been subjected to the film formation process is determined. A film thickness monitoring device for monitoring,
An output unit for outputting a measurement signal whose frequency changes within a predetermined range to the piezoelectric element;
A receiving unit that receives the measurement signal and a reflection signal obtained by reflecting the measurement signal by the piezoelectric element;
Based on the received measurement signal and the reflected signal, a frequency characteristic of impedance and a phase frequency characteristic of the piezoelectric element are obtained to obtain a resonance frequency of the piezoelectric element, and based on the obtained change amount of the resonance frequency. And a monitoring unit that monitors the film thickness of the film formed on the film formation target.

The output unit is
A signal distributor for distributing the measurement signal to an input signal and a reference signal, and inputting the input signal to the piezoelectric element;
A signal separator that separates the input signal and a reflected signal reflected by the piezoelectric element from the input signal;
The receiving unit receives the reference signal distributed by the signal distributor and the reflected signal separated by the signal separator,
The monitoring unit obtains an impedance frequency characteristic and a phase frequency characteristic of the piezoelectric element based on the received reference signal and the reflected signal to obtain a resonance frequency of the piezoelectric element and an equivalent circuit parameter. The film thickness of the film formed on the film formation target may be monitored based on the obtained change amount of the resonance frequency and the obtained parameter of the equivalent circuit.

  The monitoring unit may monitor the life of the piezoelectric element based on the obtained parameter of the equivalent circuit.

  The monitoring unit sweeps a frequency band of a preset range including the resonance frequency of the piezoelectric element, and the resonance frequency of the piezoelectric element and the equivalent circuit of the equivalent circuit are determined from the frequency characteristic of the impedance of the piezoelectric element and the frequency characteristic of the phase. A parameter may be obtained.

The piezoelectric element is a crystal resonator,
The parameter of the equivalent circuit of the crystal unit may be crystal impedance.

  The piezoelectric element is provided with a pair of electrodes on both opposing principal surfaces, the electrode disposed on one principal surface of the piezoelectric element is grounded, and the electrode disposed on the other principal surface is connected to the output unit May be.

A piezoelectric element holder that accommodates the plurality of piezoelectric elements by arranging a plurality of piezoelectric elements around a predetermined axis in the circumferential direction, with one main surface of each of the piezoelectric elements facing the bottom, Includes a piezoelectric element holder in which an opening for introducing a film forming material is formed at a position where any one of the accommodated piezoelectric elements faces.
A rotation drive unit that rotates the plurality of piezoelectric elements around the predetermined axis in the piezoelectric element holder;
Based on the parameters of the preset equivalent circuit, determine the replacement time of the piezoelectric element facing the opening, and when it is determined that it is the replacement time, the rotation drive unit, the plurality of piezoelectric elements, A first control unit that rotates around the predetermined axis in the piezoelectric element holder and moves a piezoelectric element other than the piezoelectric element facing the opening so as to face the opening; Prepared,
The output unit may output a measurement signal in which the frequency changes within a predetermined range to a piezoelectric element facing the opening.

A film forming apparatus according to a second aspect of the present invention includes:
The film thickness monitoring device;
An evaporation source for evaporating a film forming material formed on the film formation target;
Based on the resonance frequency of the piezoelectric element, a deposition rate of a film to be deposited on the deposition target is obtained, and the deposition is performed so that the deposition rate is within a preset deposition rate range. And a second control unit that controls the evaporation rate of the film forming material evaporated from the source.

The film thickness monitoring method according to the third aspect of the present invention is:
Using a piezoelectric element disposed in the same film formation chamber as the film formation target disposed in the film formation chamber, the film thickness of the film formed on the film formation target that has been subjected to the film formation process is determined. A film thickness monitoring method for monitoring,
An output step of outputting a measurement signal whose frequency changes within a predetermined range to the piezoelectric element;
Receiving the measurement signal and a reflected signal obtained by reflecting the measurement signal by the pressure element;
Based on the received measurement signal and the reflected signal, a frequency characteristic of impedance and a phase frequency characteristic of the piezoelectric element are obtained to obtain a resonance frequency of the piezoelectric element, and based on the obtained change amount of the resonance frequency. And a monitoring step of monitoring the film thickness of the film formed on the film formation target.

  According to the present invention, it is possible to accurately monitor the film thickness formed on the film formation target by detecting the frequency characteristics of the piezoelectric element without using an oscillator.

1 is a conceptual diagram of a film forming apparatus including a film thickness monitoring apparatus according to Embodiment 1. FIG. It is sectional drawing of the crystal oscillator holder connected to the film thickness monitoring apparatus. It is a figure which shows the basic composition of a film thickness monitoring apparatus. It is a functional block diagram of a film thickness monitoring apparatus. It is a graph which shows the frequency characteristic of the impedance of a crystal oscillator, and the frequency characteristic of a phase. It is a figure which shows the impedance frequency characteristic for every film-forming. It is a graph which shows the impedance frequency characteristic of a main vibration and a secondary vibration. It is a figure which shows the equivalent circuit of a crystal oscillator. It is a graph which shows the relationship between a frequency and CI value. It is another graph which shows the frequency characteristic of the impedance of a crystal oscillator, and the frequency characteristic of a phase. 6 is a schematic view of a crystal resonator holder of a film thickness monitoring apparatus according to Embodiment 2. FIG. It is a functional block diagram of a film thickness monitoring apparatus. It is a flowchart of a crystal oscillator exchange process. 10 is a flowchart of a crystal resonator replacement process according to Modification 1. 10 is a flowchart of a crystal resonator replacement process according to Modification 2. It is a graph used when determining the upper limit of CI value. 10 is a flowchart of a film forming rate control process in the film forming apparatus according to the third embodiment.

  Embodiments of a film thickness monitoring apparatus according to the present invention will be specifically described below with reference to the accompanying drawings. Note that the embodiments described below are for explanation, and do not limit the scope of the present invention. Accordingly, those skilled in the art can employ embodiments in which each or all of these elements are replaced with equivalent ones, and these embodiments are also included in the scope of the present invention.

(Embodiment 1)
A film forming apparatus including the film thickness monitoring apparatus of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the film forming apparatus 1 according to the first embodiment includes a film thickness monitoring apparatus 10, a crystal resonator holder 20, a vapor deposition source 30, a substrate holder 40, and a first controller 50. .

  The film forming apparatus 1 is an apparatus that heats a vapor deposition material in a vacuum atmosphere and deposits the vapor deposition material vaporized by heating as a film on a substrate that is a film formation target. The film forming apparatus 1 includes a film forming chamber 2, and a crystal resonator holder 20, a vapor deposition source 30, and a substrate holder 40 are accommodated in the film forming chamber 2. A vacuum pump 3 is connected to the film forming chamber 2, and the inside of the film forming chamber 2 is exhausted by the vacuum pump 3 until a predetermined degree of vacuum is reached. As the vacuum pump 3, a turbo molecular pump, a cryopump or the like is used.

  In the first embodiment, a film formation process by a vacuum evaporation method is applied, but the method of the film formation process is not limited to the vacuum evaporation method. For example, in a vacuum atmosphere filled with an inert gas such as argon, a voltage is applied to the target, ionized argon atoms collide with the target, target atoms are knocked out, and sputtering is performed to form a substrate with the atoms. A film formation process may be applied.

  The film thickness monitoring apparatus 10 is an apparatus that monitors the thickness of a film deposited on a substrate on which a film forming process is performed. In the first embodiment, a network analyzer is used. Details of the film thickness monitoring device 10 will be described later.

  The crystal resonator holder 20 is a holder for holding the crystal resonator 23, and is formed of a conductive material such as metal.

  FIG. 2 shows a schematic diagram of the crystal unit holder 20 that holds the crystal unit 23. The crystal resonator holder 20 includes a holder main body 21, a lid portion 22, and a spring electrode 26.

  The holder main body 21 is formed in a concave shape, and a circular opening 21b is formed in the concave bottom portion 21a when viewed from above. The opening 21 b is a hole through which the film forming material vaporized from the vapor deposition source 30 is introduced into the holder main body 21. The crystal unit 23 is held inside the holder body 21 in a state in which the vapor deposition surface 23a, which is one main surface of the crystal unit 23, is arranged to face the bottom 21a.

  The lid 22 is a member that closes the concave opening of the holder body 21.

  The crystal resonator 23 is a disk-shaped crystal resonator 23 and includes main surfaces 23a and 23b facing each other. Here, the main surface to which the film forming material adheres is referred to as a vapor deposition surface 23a, and the main surface to which the film forming material does not adhere is referred to as a non-deposition surface 23b. Although the first embodiment will be described using the crystal resonator 23, the present invention may be any piezoelectric element and can be similarly applied to a piezoelectric ceramic or the like.

  A first electrode portion 24 is provided on the vapor deposition surface 23 a of the crystal resonator 23, and a second electrode portion 25 is provided on the non-vapor deposition surface 23 b. The first electrode unit 24 has a function as a ground electrode, and is grounded via any component of the film forming apparatus 1, for example, the holder body 21. The second electrode unit 25 is electrically connected to the film thickness monitoring device 10 via a spring electrode 26 described later.

  The spring electrode 26 is an elastic member made of a metal material. The spring electrode 26 is inserted between the crystal resonator 23 and the lid 22, is compressed by the lid 22, and is accommodated in the holder main body 21. The spring electrode 26 has flexibility to restrict the movement of the crystal unit 23 in the holder body 21 and to allow the crystal unit 23 to vibrate.

  When the crystal resonator 23 is accommodated in the holder body 21, the spring electrode 26 comes into contact with the plate surface of the lid portion 22 and is electrically connected to the film thickness monitoring device 10.

  The vapor deposition source 30 is an apparatus that heats the film forming material filled in the crucible and vaporizes the film forming material. As a heating method, a resistance heating method, a high frequency induction heating method, an electron beam heating method, or the like is applied. The vapor deposition source 30 is installed at the bottom of the film formation chamber 2, and the crystal resonator holder 20 is disposed at a position facing the direction in which the film formation material of the vapor deposition source 30 evaporates.

  The substrate holder 40 is a member that holds a substrate 41 that is a deposition target. The vapor deposition surface of the substrate 41 held by the substrate holder 40 faces the direction in which the film forming material of the vapor deposition source 30 evaporates, and the evaporated film forming material is vapor deposited on the vapor deposition surface.

  The first controller 50 controls operations of the vapor deposition source 30 and the film thickness monitoring device 10. It is comprised from a processor, memory, etc., and the control program of the film-forming apparatus 1 is stored in the memory. The first controller 50 controls the entire film forming apparatus 1 according to this control program.

  Next, details of the film thickness monitoring apparatus 10 will be described with reference to FIGS. A basic configuration of the film thickness monitoring apparatus 10 is shown in FIG. The film thickness monitoring device 10 includes a signal source 11, a signal distributor 12, a signal separator 13, a receiver 14, a second controller 15, and a display 16.

  The signal source 11 is a device that applies a sine wave signal that is a measurement signal to the crystal resonator 23 that is a measurement target. The signal source 11 can sweep the frequency, and can change the frequency of the sine wave signal to be generated within a predetermined range.

  The signal distributor 12 is a device that distributes the sine wave signal transmitted from the signal source 11 into an input signal input to the crystal unit 23 and a reference signal directly sent to the receiver 14. The signal separator 13 is a device that separates an input signal incident on the crystal resonator 23 and a reflected signal reflected from the crystal resonator 23. In the first embodiment, a directional coupler is used as the signal separator 13. The signal separator 13 only needs to be a device that can separate an input signal and a reflected signal, and for example, an SWR bridge may be used.

  The receiver 14 receives a sine wave signal that is a reference signal distributed by the signal distributor 12 and a reflected signal that is distributed by the signal distributor 12 and input to the crystal oscillator 23 and reflected by the crystal oscillator 23. It is a device to do. The receiver 14 transmits the received signal to the second controller 15.

  Based on the signal transmitted from the receiver 14, the second controller 15 obtains the resonance frequency and the parameters of the equivalent circuit of the crystal resonator 23 from the frequency characteristics of the impedance and the phase of the crystal resonator 23. The film thickness of the film forming material deposited on the crystal resonator 23 is calculated from the detected change amount of the resonance frequency. The second controller 15 calculates the film thickness of the film deposition material deposited on the substrate 41 and the film deposition rate, which is the amount of change in film thickness per unit time, from the film thickness of the film deposition material deposited on the crystal unit 23. To do. In order to convert the film thickness of the film forming material deposited on the crystal unit 23 into the film thickness of the film forming material deposited on the substrate 41, a process such as multiplication by a correction coefficient may be performed. The second controller 15 includes a processor, a memory, and the like, and stores a control program for the film thickness monitoring device 10 in the memory.

  The display 16 is a device that displays the film thickness of the film forming material deposited on the substrate 41 and the film forming rate obtained by the second controller 15, and includes a monitor. The display device 16 may display the frequency characteristics of the impedance and the frequency characteristics of the phase, the resonance frequency, and the parameters of the equivalent circuit of the crystal unit 23.

  Next, a functional block diagram of the film thickness monitoring apparatus 10 according to the first embodiment will be described with reference to FIG.

  The film thickness monitoring device 10 includes an output unit 17, a receiving unit 18, and a monitoring unit 19.

  The output unit 17 applies a measurement signal, which is a sine wave signal whose frequency changes within a predetermined range, to the crystal unit 23. The range of the changing frequency can be changed according to the type of the crystal resonator 23 to be handled. In the first embodiment, the sweep width is appropriately determined within the range of 5.5 MHz to 6 MHz. The measurement signal output from the output unit 17 is distributed to the reference signal and the input signal, and the input signal is input to the crystal unit 23. The signal source 11, the signal distributor 12, and the signal separator 13 function as the output unit 17.

  The receiving unit 18 receives a part of the measurement signal output from the output unit 17 as a reference signal. The receiving unit 18 receives a reflected signal reflected by the crystal unit 23 with respect to the input signal. The receiver 14 functions as the receiving unit 18.

  The monitoring unit 19 obtains the impedance frequency characteristic and the phase frequency characteristic of the crystal unit 23 based on the reference signal and the reflection signal received by the reception unit 18, and calculates the resonance frequency and equivalent circuit parameters of the crystal unit 23. Ask for. Then, the film thickness formed on the substrate 41 is monitored based on the obtained amount of change in the resonance frequency of the crystal unit 23. The second controller 15 and the display device 16 function as the monitoring unit 19.

  The frequency characteristic of the crystal unit 23 is obtained from the phase difference and amplitude ratio of both signals by comparing the input signal and the reflected signal. FIG. 5 shows the obtained frequency characteristics of impedance and phase. In FIG. 5, a graph X is a graph showing a change in impedance due to a frequency, and a graph Y is a graph showing a change in phase. The impedance is indicated by Z in the figure.

  When obtaining the resonance frequency and equivalent circuit parameters from the impedance frequency characteristics and phase frequency characteristics shown in FIG. 5, instead of using all the data of the graph X, the frequency band in a predetermined range is swept. ) And analyze the data in that range. For example, the frequency band near the resonance frequency is swept in the range of 300 Hz (51 points).

  The frequency characteristics of the impedance and the phase frequency characteristics of the crystal unit 23 are obtained continuously by changing the frequency band to be swept during one film forming process gradually. FIG. 6 shows changes in the frequency characteristics of the impedance of the crystal unit 23 when the film forming process is performed. The sweep region is selected so as to always include the series resonance point of the crystal unit 23 in the band. The sweep region may be gradually shifted to the low frequency side in conjunction with the speed at which the film is deposited on the crystal resonator. Specifically, the series resonance point of the next measurement may be predicted based on the value of the resonance frequency measured immediately before and the film formation rate, and the frequency band may be determined so as to have a width before and after the predicted value. By gradually shifting the sweep region, it is possible to always follow the series resonance due to the main vibration, so that the resonance frequency can be monitored without confusion between the main vibration and the sub vibration.

  As shown in FIG. 6, the frequency band of a predetermined range is swept according to the film thickness, and the data of the range is analyzed to obtain the resonance frequency and the equivalent circuit parameters. By sweeping the frequency band in a predetermined range, analysis with high frequency resolution is possible while maintaining the analysis processing speed. Note that the maximum frequency resolution of the network analyzer used in the first embodiment is 1601 points.

  FIG. 7 shows impedance frequency characteristics of main vibration and sub vibration. In the figure, the vibration characteristic existing on the low frequency side is the main vibration, and the two vibration characteristics existing on the high frequency side are the secondary vibrations. Since the illustrated secondary vibration has a smaller impedance than the main vibration, a frequency jump occurs in the conventional crystal oscillation type film thickness monitoring method, and the resonance frequency of the main vibration cannot be measured. However, with the film thickness monitoring device 10 of the present invention, the main vibration and the sub vibration can be identified from the frequency characteristics of the impedance, and the resonance frequency of the main vibration can be measured. The secondary vibration is a generic term for all unnecessary vibrations other than the main vibration, such as vibrations in different modes, contour sliding vibration, and bending vibration.

  The monitoring unit 19 obtains the resonance frequency and equivalent circuit parameters of the crystal unit 23 by obtaining the frequency characteristics of the impedance and the phase of the crystal unit 23. Hereinafter, an equivalent circuit of the crystal unit 23 will be described.

  The crystal unit 23 can be electrically displayed as an equivalent circuit shown in FIG. The equivalent circuit includes a series inductance L1, a series capacitor C1, a parallel capacitor C0, and a series resistor R1. The values indicated by L1, C1, C0, and R1 are a kind of parameters of the equivalent circuit and can be used for monitoring the film thickness.

  In the frequency characteristics of the crystal unit 23 shown in FIG. 5, the frequency at the point A (series resonance point) where the line of the graph X intersects the 0 ° phase portion of the graph Y is the series resonance frequency (in this specification, simply Similarly, the frequency at point B is the parallel resonance frequency. The film thickness of the film formed on the substrate 41 can be monitored by converting the change amount of the resonance frequency into the film thickness and tracking the change.

  A graph showing the relationship between the resonance frequency measured using the film thickness monitoring device 10 and the CI value is shown in FIG. The CI value indicates the value of crystal impedance and is equal to R1 which is a parameter of an equivalent circuit of the crystal unit 23. As shown in FIG. 9, the CI value increases as the thickness of the film deposited on the crystal unit 23 increases (as the load mass increases). This is synonymous with the fact that the smaller the CI value is, the easier it is to oscillate, and the thinner the film thickness, and the larger the CI value, the more difficult it is to oscillate, and the thicker the film thickness. Therefore, the usage limit of the crystal unit 23 can be monitored by tracking the change in the CI value.

  Furthermore, the admittance that is the reciprocal of the impedance can be obtained, and the parameters of the equivalent circuit of the crystal unit 23 can be obtained. The admittance (Y) can be represented by a real part and an imaginary part of Y = G + jB (G: conductance, B: susceptance). By obtaining the frequency characteristics of the admittance conductance, for example, the Q value and the D value can be obtained. The Q value is a parameter indicating the ease of resonance of the crystal resonator, and the D value is a reciprocal of the Q value and is a parameter indicating the energy loss of the crystal resonator.

  The monitoring unit 19 monitors the film thickness formed on the substrate 41 based on the resonance frequency and the equivalent circuit parameters thus obtained. Specifically, the change in the deposition rate is monitored by converting the obtained amount of change in the resonance frequency per unit time into the deposition rate. The film formation rate is a value indicating how fast the film is formed. In the first embodiment, the film formation rate is expressed in units of Å / s. The monitoring unit 19 displays the film formation rate on the monitor of the display 16. The user can confirm the state of film formation by monitoring the change in the film formation rate displayed on the monitor.

  The monitoring unit 19 monitors changes in the CI value. The monitoring unit 19 may display the obtained change in the CI value on the monitor of the display 16. The user can predict the lifetime of the crystal resonator as a monitor by looking at the change in the CI value displayed on the monitor.

  A method of monitoring the film thickness in the film thickness monitoring apparatus 10 having such a configuration will be described. The method is executed under the control of the second controller 15.

  First, the inside of the film forming chamber 2 is evacuated by the vacuum pump 3 to start the film forming process. When the film forming process is started, the film forming material of the evaporation source 30 is heated and vaporized, and the film forming material is evaporated on the evaporation surface of the substrate 41 to be formed. The vaporized film forming material is introduced from the opening 21 b of the crystal resonator holder 20 and adheres to the vapor deposition surface 23 a of the crystal resonator 23.

  The signal source 11 outputs a measurement signal whose frequency changes within a predetermined range. The measurement signal is a reference signal input to the receiver 14 by the signal distributor 12 and an input signal input to the crystal unit 23. Distributed to. A part of the input signal input to the crystal unit 23 is reflected as a reflected signal. The reference signal and the reflected signal are input to the receiver 14 (reception unit 18).

  The receiver 14 (reception unit 18) receives the reference signal and the reflected signal, and transmits both signals to the second controller 15. The second controller 15 (monitoring unit 19) obtains the frequency characteristics of the impedance and the phase of the crystal oscillator 23 based on the received reference signal and reflection signal, and obtains the resonance frequency of the crystal oscillator. . Then, the second controller 15 calculates the film thickness and film formation rate of the film formed on the substrate 41 based on the amount of change in the resonance frequency.

  The second controller 15 displays the obtained film thickness of the substrate 41 and the film formation rate on the monitor of the display 16.

  According to the first embodiment, the resonance frequency is detected based on the impedance characteristics and phase characteristics of the crystal resonator without using an oscillator as in the crystal oscillation type film thickness monitoring method. Therefore, unlike the crystal oscillation type film thickness monitoring method, the situation where the oscillation becomes unstable or the oscillation stops and the resonance frequency cannot be measured does not occur. In addition, the resonance frequency of the main vibration can be accurately detected without being affected by the secondary vibration. Furthermore, since not only the resonance frequency but also the impedance characteristic and phase characteristic of the crystal resonator can be detected, it can be used for film formation rate control and life management of the crystal resonator.

  According to the first embodiment, the film formation rate can be controlled without being affected by the secondary vibration even when the secondary vibration occurs. For example, FIG. 10 shows waveform distortion caused by secondary vibration. As shown in FIG. 10, when affected by the secondary vibration, the waveform of the graph showing the frequency characteristics of the impedance and the waveform showing the phase change. In such a case, it is determined that the secondary vibration is generated from the waveform distortion, and the power of the vapor deposition source is controlled using the control value calculated from the immediately preceding resonance frequency measurement value. In the conventional crystal oscillation type film thickness monitoring method, there has been a problem that the film formation rate becomes unstable by feeding back the fluctuation of the resonance frequency caused by the secondary vibration to the film formation rate control. In 1, not only the resonance frequency but also the frequency characteristics of the phase and impedance as shown in FIG. 10 can be acquired, so that it is possible to control to remove the influence of other vibration modes other than the main vibration.

  According to the first embodiment, the resonance frequency of the crystal resonator and the parameters of the equivalent circuit are determined from the input signal and the reflected signal reflected from the input signal without using the passing signal that the input signal has passed through the crystal resonator. Seeking. Therefore, the first electrode portion 24 attached to the other main surface of the crystal unit 23 can be grounded, and the wiring structure can be simplified.

(Embodiment 2)
In the first embodiment, the film thickness monitoring apparatus 10 using one crystal resonator 23 has been described. However, the present invention is not limited to using one crystal resonator, and a plurality of crystal resonators are used. You may apply to the film thickness monitoring apparatus which monitors a film thickness.

  A film forming apparatus including the film thickness monitoring apparatus according to the second embodiment includes a film thickness monitoring apparatus 100, a crystal resonator holder 200, a vapor deposition source 30, a substrate holder 40, and a first controller 50. . The vapor deposition source 30, the substrate holder 40, and the first controller 50 have the same configuration as shown in FIG. FIG. 11 shows the film thickness monitoring device 100, the crystal resonator holder 200, and the rotation drive mechanism 300 that rotates the crystal resonator holder 200. Further, the same crystal unit as the crystal unit 23 used in the first embodiment is used.

  As shown in FIG. 11, the crystal unit holder 200 is connected to the film thickness monitoring device 100 and the rotation drive mechanism 300, and the film thickness monitoring device 100 is connected to the rotation drive mechanism 300.

  As shown in FIG. 11, the crystal resonator holder 200 includes a head part 210, a holder main body 220, and a cover part 230.

  The head portion 210 is a cylindrical member that rotates about the rotation shaft 201, and a plurality of spring electrodes 26 are attached to one end of the head portion 210 in the circumferential direction about the rotation shaft 201. The spring electrode 26 is fixed to the head portion 210 by a screw 26a using the same member as the spring electrode 26 applied in the first embodiment.

  The holder main body 220 is a disk-shaped member made of a conductive material such as metal. The holder body 220 is disposed to face one end surface of the head portion 210 where the spring electrode 26 is provided. The bottom 220a of the holder body 220 is provided with a plurality of first openings 220b around an axis coaxial with the rotation shaft 201. A plurality of crystal resonators 23 are accommodated at positions corresponding to the plurality of first openings 220b so as to face the head unit 210. The holder main body 220 includes a cylindrical fitting portion 221 that protrudes from the center of the disc toward the head portion 210. The shaft end of the rotating shaft 201 of the head part 210 is fitted to the cylindrical fitting part 221, and the holder main body 220 is attached to the head part 210. The holder main body 220 is rotated coaxially with the rotation shaft 201 of the head unit 210.

  The rotation drive mechanism 300 is a drive member that rotates the head unit 210 around the rotation shaft 201, and for example, a pulse motor is applied.

  The cover part 230 is a disc-shaped cover that covers the holder main body 220 from the bottom part 220a side. The cover part 230 corresponds to the bottom part of the entire crystal unit holder 200. The cover 230 is formed with a second opening 231 having the same diameter as the first opening 220 b formed in the holder main body 220. The second opening 231 is arranged so as to face any one of the plurality of first openings 220b formed in the holder main body 220.

  The first electrode portion 24 attached to the main surface on the vapor deposition surface 23a side of the crystal unit 23 is grounded to the holder body 220, and the second electrode attached to the main surface opposite to the vapor deposition surface 23a. The unit 25 is connected to the film thickness monitoring device 100.

  The basic configuration of the film thickness monitoring apparatus 100 is the same as that shown in FIG. 3, and the film thickness monitoring apparatus 100 includes a signal source 11, a signal distributor 12, a signal separator 13, a receiver 14, and a second controller. 15 and a display 16 are provided. The description about each structure is abbreviate | omitted.

  A functional block diagram of the film thickness monitoring apparatus 100 is shown in FIG. The film thickness monitoring apparatus 100 includes a first control unit 140, a rotation driving unit 150, an output unit 160, a receiving unit 170, and a monitoring unit 180. The output unit 160, the reception unit 170, and the monitoring unit 180 have the same functions as the output unit 17, the reception unit 18, and the monitoring unit 19 illustrated in FIG.

  The first control unit 140 determines the life of the crystal unit 23 and, when determining that the life has reached, rotates the holder main body 220 of the crystal unit holder 200 around the rotation axis 201 by the rotation driving unit 150. Control as follows. The second controller 15 of the film thickness monitoring device 100 functions as the first control unit 140.

  The rotation driving unit 150 receives a signal from the first control unit 140 indicating that the crystal unit 23 has a lifetime, and rotates the holder body 220 of the crystal unit holder 200 around the rotation axis 201. . The rotation drive mechanism 300 functions as the rotation drive unit 150.

  After the holder main body 220 of the crystal unit holder 200 is rotated by the rotation driving unit 150, the film forming process is started, and the film thickness formed on the substrate 41 by the output unit 160, the receiving unit 170, and the monitoring unit 180. To monitor.

  A method for replacing the crystal unit 23 while monitoring the film thickness in the film thickness monitoring apparatus 10 having such a configuration will be described with reference to the flowchart shown in FIG.

  First, a film formation process is actually performed to measure a CI value, and an upper limit of the CI value is set based on the actually measured value (step S1001). Specifically, each time a plurality of film formation processes are performed on the substrate, the film formation rate and the CI value are obtained, and the upper limit of the CI value is set based on the result. FIG. 16 is a graph showing the relationship between the CI value and the deposition rate when a plurality of films are deposited on the substrate 41. The solid line indicates the deposition rate for each film, and the broken line indicates the CI value. On the substrate 41, a first film, a second film,..., An eighth film, and a film are laminated one by one, and a plurality of deposited layers are deposited. As shown in FIG. 16, when the film formation process is executed from the first film to the eighth film, the waveform indicating the film formation rate is disturbed from the time when the sixth film is formed, and the film formation rate is not stable. You can see that it is stable. Therefore, the CI value when the sixth film is formed is defined as the upper limit of the CI value.

  Next, the CI value before film formation on the substrate 41 is obtained by the first control unit 140 (step S1002). Specifically, the CI value is obtained by obtaining the frequency characteristic of the impedance and the frequency characteristic of the phase of the crystal unit 23 using a measuring device such as a network analyzer.

  Next, the first control unit 140 predicts a CI value after film formation based on a preset film thickness input in advance by the user (step S1003).

  Then, the first control unit 140 determines whether or not the predicted CI value is larger than the upper limit CI value (step S1004). When the predicted CI value is larger than the upper limit CI value (step S1004: YES), the first control unit 140 determines that the life of the crystal unit 23 has reached the end.

  When the first control unit 140 determines that the life of the crystal unit 23 has expired, the first control unit 140 instructs the rotation drive unit 150 to rotate the holder body 220 of the crystal unit holder 200 in a predetermined direction by a predetermined angle. To do. Specifically, in the rotation drive mechanism 300, the unused crystal unit 23 arranged next to the crystal unit 23 that has been determined to have reached the end of life faces the second opening 231 of the cover unit 230. The holder main body 220 is rotated so that the quartz vibrator is switched (step S1005). After the switching to the unused crystal unit 23 is completed, the film forming process on the substrate 41 is started (step S1006).

  When the film forming process is started, the film forming material of the evaporation source 30 is heated and vaporized, and the film forming material is evaporated on the evaporation surface of the substrate 41 to be formed. On the other hand, the holder main body 220 and the cover portion 230 are such that one of the plurality of crystal resonators accommodated in the holder main body 220 is connected to the second opening portion 231 of the cover portion 230 via the first opening portion 220b. And are arranged to correspond. Then, the film forming material is introduced into the holder main body 220 from the second opening 231, and the film forming material adheres to the vapor deposition surface 23 a of the crystal unit 23.

  When the film forming process is started, the film thickness monitoring process is started as in the first embodiment (step S1007). The signal source 11 outputs a measurement signal whose frequency changes within a predetermined range. The measurement signal is a reference signal input to the receiver 14 by the signal distributor 12 and an input signal input to the crystal unit 23. Distributed. A part of the input signal input to the crystal unit 23 is reflected as a reflected signal. The reflected signal is separated by the signal separator 13, and the reference signal and the reflected signal are received by the receiver 14.

  The receiver 14 that has received the reference signal and the reflected signal transmits both signals to the second controller 15. The second controller 15 obtains the impedance frequency characteristic and the phase frequency characteristic of the crystal resonator 23 based on the reference signal and the reflected signal, and obtains the resonance frequency and equivalent circuit parameters of the crystal resonator 23. The film thickness of the film formed on the substrate 41 is monitored based on the obtained change amount of the resonance frequency.

  On the other hand, when the first control unit 140 determines that the predicted CI value is smaller than the upper limit CI value (step S1004: NO), the film forming process is started as it is (step S1006), and the film thickness is monitored. Is also started (step S1007).

  Then, the monitoring unit 180 monitors the film thickness to determine whether or not the film forming process has ended (step S1008). When the film forming process has ended (step S1008: YES), the process ends. To do. If the film forming process has not been completed (step S1008: NO), before starting the next film forming process, the CI value before film forming is measured (step S1002), and the same process is repeated. Here, “the film formation process has been completed” includes a case where it is determined that the predetermined film thickness has been reached, or a case where it is determined that all the films have been formed when a plurality of films are stacked.

(Modification 1)
In the flowchart shown in FIG. 13, it is determined whether or not the crystal unit 23 needs to be replaced before the start of film formation. However, the crystal unit 23 may be determined to be replaced while monitoring the CI value during the film formation process. An example in which film formation is performed while monitoring the CI value will be described using the flowchart shown in FIG.

  First, the upper limit of the CI value is set as in the case where it is determined whether or not the crystal unit 23 needs to be replaced before the film formation is started (step S1101).

  Next, a film forming process on the substrate 41 is started (step S1102), and the first control unit 140 acquires a CI value from the frequency characteristic of the impedance and the phase frequency characteristic of the crystal unit 23 during film formation. (Step S1103), it is determined whether or not the actually measured CI value is larger than the upper limit CI value (Step S1104). When the actually measured CI value is larger than the upper limit CI value (step S1104: YES), the first control unit 140 determines that the life of the crystal unit 23 has been reached.

  When the first control unit 140 determines that the life of the crystal unit 23 has expired, the film formation is stopped (step S1105), and the crystal unit holder 200 is operated to switch to the unused crystal unit 23. This is performed (step S1106). After the switching to the unused crystal unit 23 is completed, the film forming process on the substrate 41 is started (step S1102).

  When the film formation process is started, the CI value measurement (step S1103), the film formation stop determination (step S1104), the film thickness monitoring (step S1107), and the film formation process end determination (step S1108) are repeated. If the process has been completed (step S1108: YES), the process is terminated.

  When the actually measured CI value is smaller than the upper limit CI value (step S1104: NO), the film thickness is monitored (step S1107), and the end of the film forming process is determined (step S1108).

  If the film forming process has not been completed (step S1108: NO), the film forming process is continued and the process is repeated. If the film forming process has ended (step S1108: YES), the process ends.

  In the flowchart shown in FIG. 14, the film formation is stopped when the actually measured CI value is larger than the upper limit CI value. However, the film formation is not stopped, the immediately preceding vapor deposition source power is maintained, and the film formation is continued. You may let them. The time required to reach the target film thickness may be calculated from the immediately preceding film formation rate, and the film formation process may be terminated simultaneously with the lapse of the calculation time.

  According to Modification 1, the upper limit value of the CI value is set, and the CI value is measured while forming the film. Therefore, the lifetime of the crystal resonator is longer than when the crystal resonator is replaced by predicting the CI value. Can be extended.

(Modification 2)
In the first modification, one upper limit value of the CI value is set to determine the replacement time of the crystal unit. However, the present invention is not limited to the case where one upper limit value of the CI value is set, and by setting a plurality of upper limit values and performing processing according to each upper limit value, the replacement time of the crystal unit can be set. It is possible to delay the life of the crystal unit.

  In this modification, three upper limit values are set as upper limit values of the CI value. As shown in FIG. 16, the CI value increases as the film thickness increases, and the film formation rate is disturbed. In the second embodiment, as shown in FIG. 16, the CI value when the sixth film whose film formation rate is increasing is being formed is set as the upper limit value for exchanging the crystal resonator. Set.

  On the other hand, the CI value rises temporarily due to the influence of temperature and sub-vibration, shows the value of the CI value that becomes the upper limit value, and shows a change that falls below the upper limit value when these influences disappear. is there. In such a case, if it is determined that the CI value has increased and feedback is applied so as to control the film formation rate, the increase in the CI value due to the film thickness is not the main cause of the increase. It becomes difficult to control.

  In the present modification, the upper limit value of the CI value defined in FIG. 16 is set as the first upper limit value, and the waveform of the film formation rate in the eighth film in FIG. Was set as the third upper limit value. A CI value between the first upper limit value and the third upper limit value is set as the second upper limit value. The upper limit values of the three CI values have a relationship of first upper limit value <second upper limit value <third upper limit value.

  When the CI value becomes a value between the first upper limit value and the second upper limit value, the film formation rate control is turned off so that the fluctuation of the CI value is not fed back to the film formation rate control. Continue to use crystal units. Thereafter, when the CI value becomes equal to or lower than the first upper limit value, the film formation rate control is turned on and the film formation is continued.

  When the CI value becomes a value between the second upper limit value and the third upper limit value, the film formation rate control is turned OFF, and the film formation process of the film formation layer formed at that time is completed. Then replace the crystal unit. When the CI value is larger than the third upper limit value, the film formation is immediately stopped and the crystal resonator is replaced.

  Such a crystal resonator replacement process will be described in detail with reference to the flowchart shown in FIG. In the flowchart, Y indicates “YES” and N indicates “NO”.

  First, the first upper limit value and the third upper limit value of the CI value are set using the graph shown in FIG. 16, and the value between the first upper limit value and the third upper limit value is set to the second value. The upper limit value is set (step S1301). Then, a film forming process is started (step S1302). The second upper limit value is set at an arbitrary position between the first upper limit value and the third upper limit value according to the characteristics of the graph indicating the film formation rate.

  When the film forming process is started, the first control unit 140 measures the CI value of the crystal unit 23 (step S1303), and if the CI value is equal to or less than the first upper limit value (step S1304; YES) ), The film formation rate control is turned ON (step S1305). Then, the monitoring unit 180 monitors the film thickness (step S1306). The first controller 140 determines whether or not the formation of the layer being formed has been completed (step S1307). If it is determined that the formation has been completed (step S1307; YES), the formation of all layers has been completed. It is determined whether or not (step S1308). If it is determined that all the layers have been formed (step S1308: YES), the process ends. If deposition of all layers is not completed (step S1308; NO), deposition of the next layer is started (step S1302).

  When the CI value is equal to or lower than the first upper limit value and it is determined that the film formation of the layer being formed is not completed (step S1307; NO), the first control unit 140 again determines the CI value. When the CI value is determined to be a value between the first upper limit value and the second upper limit value (step S1309; YES), the film formation rate control is turned off (step S1310). The film forming process is continued while maintaining the immediately preceding vapor deposition source power. By performing such a process, when the CI value is temporarily increased due to a change in temperature or secondary vibration, the film thickness can be appropriately maintained without controlling the film formation rate. Then, the monitoring unit 180 monitors the film thickness (step S1306), and the first control unit 140 determines whether or not the film formation process for the layer being formed has been completed (step S1307). If it is determined that the film formation process for the layer being formed has been completed (step S1307; YES), it is determined whether all film formation has been completed (step S1308). If it is determined that all film formation has been completed (step S1308; YES), the process is terminated. If it is determined that all film formation has not been completed (step S1308; NO), the next film formation process is started (step S1302).

  The CI value is a value between the first and second upper limit values. Even when the film formation rate control is turned off, the CI value is measured again (step S1303), and is less than or equal to the first upper limit value. When it is determined that there is a film (step S1304; YES), the film formation rate control is turned on (step S1305), and the normal film formation process proceeds.

  When the CI value is a value between the second and third upper limit values (step S1311; YES), the film formation rate control is turned off (step S1312), and the film thickness is monitored (step S1313). Until the deposition of the layer being deposited is completed, the deposition process continues with the deposition source power being constant (step S1314). Then, when all the film formation is completed (step S1315; YES), the process ends. When all the film formation is not completed (step S1315; NO), the crystal unit 23 is replaced (step S1316), and the next film formation process is started (step S1302). When the CI value is a value between the second and third upper limit values, the film formation rate control is turned off, so that the influence of temperature and sub-vibration on the film formation rate can be eliminated as much as possible. Further, since the use of the crystal unit 23 is continued until the formation of the layer being formed is completed, the life of the crystal unit 23 can be extended.

  If the CI value is equal to or greater than the third upper limit (step S1318; YES), the film forming process is immediately stopped (step S1319), and the crystal unit 23 is replaced (step S1316). If the CI value is less than or equal to the third upper limit value (step S1318; NO), the CI value is synonymous with being smaller than the first upper limit value, so the deposition rate control is turned on (step S1305). , The same processing as when the CI value is equal to or less than the first upper limit value is performed.

  According to the second modification, three upper limit values of the CI value can be set, and the film can be formed while considering the influence on the CI value of the secondary vibration and temperature, which are factors other than the film thickness. The use period of the child can be further extended from the first modification.

  In the second embodiment, the CI value is used as the parameter of the equivalent circuit for determining the replacement time of the crystal resonator, but the present invention is not limited to the CI value. In addition, a Q value, a D value, or the like may be used.

  In the second embodiment, when the life of one crystal unit 23 is reached, the head unit 210 and the holder main body 220 rotate by a predetermined angle, and the crystal unit housed in the holder main unit 220 and the second crystal unit Although the position of the opening 231 has been changed, the present invention is not limited to such a method. For example, the head part 210 and the holder main body 220 may be fixed, and the cover part 230 may be rotated to change the positions of the crystal resonator 23 and the second opening part 231.

  In the second embodiment, the second controller 15 is configured to function as the first control unit 140. However, the first controller 50 can also have the function of the first control unit 140.

  In the second embodiment, the rotation drive mechanism 300 rotates the crystal unit holder 200 so that an unused crystal unit arranged next to the crystal unit that has reached the end of life is in use. , It is not necessary to move the quartz crystal disposed next to the crystal unit. If the adjacent crystal resonator is not in a usable state due to a defective product or the like, another unused crystal resonator may be moved to the second opening 231.

  In the second embodiment, the method of obtaining the upper limit CI value in advance and exchanging the crystal resonator has been described. However, the method of obtaining the upper limit CI value in advance can also be applied to the first embodiment. Specifically, an upper limit CI value may be set in advance, and the user may check the CI value displayed on the monitor so that the replacement time of the crystal resonator can be predicted. Further, when the upper limit CI value is approached, a warning or the like may be displayed on the monitor to prompt the user to replace the crystal unit 23.

  According to the second embodiment, the film thickness monitoring apparatus 10 employs a monitoring method based on a reflection method in which a measurement signal with a swept frequency is applied and a reflection signal is received. The first electrode portion 24 attached to the main surface of the first electrode portion 24 can be grounded. Therefore, the wiring structure can be simplified, and the film thickness can be monitored by employing a crystal holder that can accommodate a plurality of crystal resonators 23 and can rotate around a predetermined rotation axis. Therefore, the film thickness can be continuously monitored.

  In the second embodiment, the second electrode portion 25 is connected to the film thickness monitoring device 10 (100) via the spring electrode 26. Although not shown, the connection between the spring electrode 26 and the film thickness monitoring device 10 has a switching structure in which only the crystal resonator 23 facing the second opening 231 is selected. The electrical length from the second electrode unit 25 to the film thickness monitoring device 10 depends on the individual difference of the spring electrode 26 and the contact state of the switching structure that selects connection between the spring electrode 26 and the film thickness monitoring device 10. The number of openings 220b is different for a plurality of paths. Due to the difference in electrical length, the crystal oscillation type film thickness meter causes a subtle difference in the amount of change in the resonance frequency. According to the second embodiment, since the electrical length of each of the plurality of paths is calibrated before measuring the crystal resonator 23, the difference in the electrical lengths of the plurality of paths is canceled out and the amount of change in the resonance frequency is accurately determined. Can be requested. When the crystal oscillation type film thickness monitoring method is employed, the resonance frequency cannot be accurately measured due to the influence of different load capacities for each of the plurality of crystal resonators.

  According to the second embodiment, an upper limit CI value is set in advance, and if the predicted CI value is larger than the upper limit CI value, the rotation drive mechanism 300 automatically rotates the holder body 220 to switch the crystal resonator. it can. Therefore, it is possible to prevent the quartz resonator from reaching the end of its life during the film formation, reduce the work burden on the user, and continuously monitor an appropriate film thickness.

(Embodiment 3)
In the first and second embodiments, the film thickness monitoring apparatus that appropriately monitors the film thickness has been described. However, based on the monitoring result of such a film thickness monitoring apparatus, film formation is performed so as to obtain an appropriate film thickness. It is also possible to provide a film formation apparatus capable of controlling the processing.

  The third embodiment is an embodiment in which a film formation rate is controlled in order to perform a film formation process so as to obtain an appropriate film thickness. The film forming apparatus used in Embodiment 3 uses the film forming apparatus 1 shown in FIG. 1, and the film forming apparatus 1 includes a film thickness monitoring device 10, a vapor deposition source 30, a first controller 50, including. The film forming apparatus 1 includes a second control unit that controls the film thickness to a predetermined film forming rate. The first controller 50 functions as a second control unit.

  The film formation rate varies depending on the film forming material when the film is formed by using the vacuum evaporation method. For example, a film forming material having a low melting point and a film forming material having a high melting point have different heating temperatures for evaporation, and a film forming rate suitable for each film forming material is set. In addition, since the film forming rate is not stable at the initial stage of the film forming process, it is necessary to check whether the film forming rate is stable. Therefore, controlling the film formation rate to a predetermined value is important in the film formation process.

  A method for controlling the film formation rate of the film formed on the substrate 41 will be described with reference to the flowchart shown in FIG.

  First, the user sets the film formation rate of the film to be deposited via the monitor of the display 16 or the like (step S1201). The second control unit heats the vapor deposition source 30 and instructs to start the film forming process on the substrate 41 (step S1202).

  Then, the second control unit causes the film thickness monitoring device 10 to obtain the frequency characteristics of the impedance and the phase of the crystal resonator 23 to obtain the resonance frequency. The film thickness monitoring apparatus 10 converts the obtained change amount of the resonance frequency into a film thickness, converts the film thickness change amount per unit time into a film formation rate, and sets the film formation rate value to the second control unit. Transmit (step S1203).

  The second control unit compares the converted film formation rate with a preset film formation rate to determine whether or not they are the same (step S1204). If the converted film formation rate is equal to the set film formation rate (step S1204: YES), the second control unit maintains the evaporation rate of the vapor deposition source 30 (step S1205) and must be the same. If so (step S1204: NO), the evaporation rate of the vapor deposition source 30 is controlled to increase or decrease to approach the set film formation rate (step 1206).

  The second control unit determines whether or not the film thickness formed on the substrate 41 has reached a predetermined film thickness based on the resonance frequency variation obtained by the film thickness monitoring device 10 (step S1207). If the predetermined film thickness is reached (step S1207: YES), the film forming process is terminated. If the predetermined film thickness is not reached (step S1207: NO), the film forming process (step S1202) is continued and the same process is repeated.

  According to the third embodiment, the film formation rate is calculated based on the amount of change in the resonance frequency per unit time obtained by the film thickness monitoring device 10. In the third embodiment, if a resonance frequency having a phase of 0 ° can be obtained in a graph showing frequency characteristics, it can be converted into a film formation rate. Therefore, the resonance frequency can be obtained more reliably than the resonance frequency measured by the crystal oscillation type film thickness monitoring method, and can be reflected in the film formation rate.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment described so far, What includes the change suitably was included.

  In the first to third embodiments, the substrate holder 40 that holds one substrate 41 has been described as an example. However, the present invention is not limited to such a substrate holder 40. For example, the present invention is also applied to a case where a plurality of substrates are held on the inner surface of a dome-shaped substrate holder, the dome is rotated, and a plurality of substrates are processed together at one time.

  In the second embodiment, the first modification, and the second modification, the crystal unit whose life has expired is described as being switched to a new crystal unit by rotating the holder main body 220 by the rotation drive mechanism 300 shown in FIG. did. The present invention is not limited to such a switching mechanism of the crystal resonator 23, and a quartz resonator holder that holds one crystal resonator is used to individually replace the quartz resonator that has reached the end of its life using an exchange device. May be.

  In the second modification, the upper limit value of the CI value is set to determine the replacement time of the crystal unit. However, the second upper limit value and the third upper limit value, or the first upper limit value and the first upper limit value are determined. A combination of two upper limit values of 3 upper limit values may be used. In Modification 2, when the CI value exceeds the first upper limit value, the film formation rate control is turned off. However, the fluctuation of the CI value is predicted in advance, and the difference between the predicted CI value and the measured CI value is a predetermined value. When it becomes above, it is good also considering the control of the film-forming rate as OFF. Alternatively, the deposition rate control may be turned off when the measured CI value fluctuation amplitude width is equal to or greater than a predetermined width.

  The present invention can be used for a film thickness monitoring apparatus that monitors the film thickness of a film formed on a surface of a substrate by a film forming process.

DESCRIPTION OF SYMBOLS 1 Film-forming apparatus 2 Film-forming chamber 3 Vacuum pump 10 Film-thickness monitoring apparatus 11 Signal source 12 Signal distributor 13 Signal separator 14 Receiver 15 Second controller 16 Display 17 Output part 18 Receiving part 19 Monitoring part 20 Crystal vibration Sub-holder 21 Holder body 21a Bottom portion 21b Opening portion 22 Lid portion 23 Crystal oscillator 23a Deposition surface 23b Non-deposition surface 24 First electrode portion 25 Second electrode portion 26 Spring electrode 26a Screw 30 Deposition source 40 Substrate holder 41 Substrate 50 1st controller 100 Film thickness monitoring device 140 1st control part 150 Rotation drive part 160 Output part 170 Reception part 180 Monitoring part 200 Crystal oscillator holder 201 Rotating shaft 210 Head part 220 Holder main body 221 Cylindrical fitting part 220a Bottom part 220b First opening 230 Cover 231 Second opening 300 Rotation drive mechanism

Claims (9)

Using a piezoelectric element disposed in the same film formation chamber as the film formation target disposed in the film formation chamber, the film thickness of the film formed on the film formation target that has been subjected to the film formation process is determined. A film thickness monitoring device for monitoring,
An output unit for outputting a measurement signal whose frequency changes within a predetermined range to the piezoelectric element;
A receiving unit that receives the measurement signal and a reflection signal obtained by reflecting the measurement signal by the piezoelectric element;
Based on the received measurement signal and the reflected signal, a frequency characteristic of impedance and a phase frequency characteristic of the piezoelectric element are obtained to obtain a resonance frequency of the piezoelectric element, and based on the obtained change amount of the resonance frequency. And a monitoring unit that monitors the film thickness of the film formed on the film formation target,
A film thickness monitoring device. The output unit is
A signal distributor for distributing the measurement signal to an input signal and a reference signal, and inputting the input signal to the piezoelectric element;
A signal separator that separates the input signal and a reflected signal reflected by the piezoelectric element from the input signal;
The receiving unit receives the reference signal distributed by the signal distributor and the reflected signal separated by the signal separator,
The monitoring unit obtains an impedance frequency characteristic and a phase frequency characteristic of the piezoelectric element based on the received reference signal and the reflected signal to obtain a resonance frequency of the piezoelectric element and an equivalent circuit parameter. Monitoring the film thickness of the film formed on the film formation target, based on the obtained change amount of the resonance frequency and the obtained parameter of the equivalent circuit;
The film thickness monitoring apparatus according to claim 1. The monitoring unit monitors the life of the piezoelectric element based on the obtained parameters of the equivalent circuit.
The film thickness monitoring apparatus according to claim 2. The monitoring unit sweeps a frequency band of a preset range including the resonance frequency of the piezoelectric element, and the resonance frequency of the piezoelectric element and the equivalent circuit of the equivalent circuit are determined from the frequency characteristic of the impedance of the piezoelectric element and the frequency characteristic of the phase. Find parameters,
The film thickness monitoring apparatus according to claim 2 or 3, wherein The piezoelectric element is a crystal resonator,
The parameter of the equivalent circuit of the crystal unit is crystal impedance.
The film thickness monitoring apparatus according to any one of claims 2 to 4, wherein The piezoelectric element is provided with a pair of electrodes on both opposing principal surfaces, the electrode disposed on one principal surface of the piezoelectric element is grounded, and the electrode disposed on the other principal surface is connected to the output unit To be
The film thickness monitoring apparatus according to any one of claims 1 to 5, wherein A piezoelectric element holder that accommodates the plurality of piezoelectric elements by arranging a plurality of piezoelectric elements around a predetermined axis in the circumferential direction, with one main surface of each of the piezoelectric elements facing the bottom, Includes a piezoelectric element holder in which an opening for introducing a film forming material is formed at a position where any one of the accommodated piezoelectric elements faces.
A rotation drive unit that rotates the plurality of piezoelectric elements around the predetermined axis in the piezoelectric element holder;
Based on the parameters of the preset equivalent circuit, determine the replacement time of the piezoelectric element facing the opening, and when it is determined that it is the replacement time, the rotation drive unit, the plurality of piezoelectric elements, A first control unit that rotates around the predetermined axis in the piezoelectric element holder and moves a piezoelectric element other than the piezoelectric element facing the opening so as to face the opening; Prepared,
The output unit outputs a measurement signal in which the frequency changes within a predetermined range to a piezoelectric element facing the opening.
The film thickness monitoring apparatus according to any one of claims 1 to 6, wherein A film thickness monitoring device according to any one of claims 1 to 7,
An evaporation source for evaporating a film forming material formed on the film formation target;
Based on the resonance frequency of the piezoelectric element, a deposition rate of a film to be deposited on the deposition target is obtained, and the deposition is performed so that the deposition rate is within a preset deposition rate range. A second controller that controls the evaporation rate of the film-forming material that evaporates from the source,
A film forming apparatus. Using a piezoelectric element disposed in the same film formation chamber as the film formation target disposed in the film formation chamber, the film thickness of the film formed on the film formation target that has been subjected to the film formation process is determined. A film thickness monitoring method for monitoring,
An output step of outputting a measurement signal whose frequency changes within a predetermined range to the piezoelectric element;
Receiving the measurement signal and a reflection signal obtained by reflecting the measurement signal by the piezoelectric element;
Based on the received measurement signal and the reflected signal, a frequency characteristic of impedance and a phase frequency characteristic of the piezoelectric element are obtained to obtain a resonance frequency of the piezoelectric element, and based on the obtained change amount of the resonance frequency. And a monitoring step of monitoring the film thickness of the film formed on the film formation target,
A film thickness monitoring method characterized by that.

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