JP7022419B2 - Film thickness monitoring device, film thickness monitoring device and film thickness monitoring method - Google Patents

Description

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

The film formation process by vacuum deposition, sputtering, or the like is performed while monitoring whether or not the film thickness deposited on the surface of the object to be deposited matches the 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 oscillator is placed in a film forming chamber in which the object to be deposited is placed, the crystal oscillator is connected to the oscillator to oscillate, and the amount of change in the resonance frequency of the crystal oscillator is measured. This is a method of converting to a film thickness. This is a monitoring method that utilizes the phenomenon that the resonance frequency of the crystal oscillator decreases when the film-forming material adheres to the surface of the crystal oscillator.

The crystal oscillation type film thickness monitoring method is applied to, for example, the 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 arranged at the bottom in the vacuum chamber 1, a substrate to be filmed, and a sensor 4 for accommodating the crystal oscillator 3. , Consists of. Then, the film thickness and the film forming speed are calculated by measuring the change in the natural frequency of the crystal oscillator 3.

Japanese Unexamined Patent Publication No. 11-160057

Since the crystal oscillation type film thickness monitoring method oscillates the crystal oscillator using an oscillator, there is a problem that an oscillation phenomenon due to a secondary vibration called a frequency jump occurs. Normally, the crystal oscillator is manufactured so that the level of the secondary vibration is sufficiently smaller than the main vibration. However, when the load mass of the crystal oscillator increases due to the accumulation of the film forming material, the secondary vibration becomes strong. The frequency jumps to the oscillation due to the secondary vibration, and the resonance frequency during monitoring 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 is lowered, which leads to the generation of defective products and the deterioration of production efficiency.

In addition, in the crystal oscillation type film thickness monitoring method, if the oscillation of the crystal oscillator becomes unstable, the film thickness measurement accuracy deteriorates significantly. It is necessary to replace the crystal oscillator because it has reached the end of its life as a sensor for monitoring the thickness of the oscillator. Further, since the method is to oscillate the crystal oscillator to detect the resonance frequency, the film thickness cannot be measured if the oscillation is stopped.

Further, in the crystal oscillation type film thickness monitoring method, since the film formation rate is controlled only based on the oscillation frequency of the crystal oscillator, the secondary vibration cannot be discriminated and the film formation rate may become unstable. Further, since the fluctuation of the resonance frequency caused by the secondary vibration is directly fed back to the film formation rate control, unnecessary power adjustment of the vapor deposition source or the like occurs. For example, when the control for maintaining the film formation rate constant is performed, the actual film formation rate may be unstable and disturbed due to the secondary vibration. In addition, the life of the crystal unit as a sensor is short, and it is necessary to replace the crystal unit frequently.

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

The film thickness monitoring device according to the first aspect of the present invention is
Using the piezoelectric element placed in the same film formation chamber as the film formation target placed in the film formation chamber, the film thickness of the film formed on the film formation target to be film-formed is determined. It is a film thickness monitoring device that monitors
An output unit that outputs a measurement signal whose frequency changes within a predetermined range to the piezoelectric element, and
A receiving unit that receives the measurement signal and a reflection signal obtained by reflecting the measurement signal by the piezoelectric element.
The impedance of the piezoelectric element for each changing frequency was measured based on the received measurement signal and the reflected signal, and the resonance frequency of the piezoelectric element was determined based on the measured impedance . A monitoring unit for monitoring the film thickness of the film formed on the object to be deposited based on the amount of change in the resonance frequency is provided.
The monitoring unit shifts the frequency band to be swept to the low frequency side in conjunction with the progress of the film forming process, measures the impedance, and determines the resonance frequency.
It is characterized by that.
The monitoring unit predicts the next resonance frequency based on the resonance frequency and the film formation rate determined by the swept frequency band, and determines the frequency band including the predicted resonance frequency as the next frequency band to be swept. You may.

The output unit is
A signal distributor that distributes the measurement signal into an input signal and a reference signal and inputs the input signal to the piezoelectric element.
Includes a signal separator that separates the input signal from the reflected signal reflected by the piezoelectric element.
The receiving unit receives the reference signal distributed by the signal distributor and the reflected signal separated by the signal separator.
The monitoring unit acquires the frequency characteristics of the impedance of the piezoelectric element based on the received reference signal and the reflected signal for each changing frequency , and the piezoelectric element is based on the frequency characteristics of the acquired impedance. The resonance frequency of the You may.

The monitoring unit may monitor the life of the piezoelectric element based on the determined parameters of the equivalent circuit.

The monitoring unit sweeps a frequency band in a preset range including the resonance frequency of the piezoelectric element, and determines the resonance frequency of the piezoelectric element and the parameters of the equivalent circuit from the frequency characteristics of the impedance of the piezoelectric element. You may .

The piezoelectric element is a crystal oscillator and is
The parameter of the equivalent circuit of the crystal oscillator may be crystal impedance.

In the piezoelectric element, a pair of electrodes are installed on both main surfaces facing each other, the electrode installed on one main surface of the piezoelectric element is grounded, and the electrode installed on the other main surface is connected to the output unit. It may have been done.
The electrode installed on one main surface of the piezoelectric element may be grounded to a component of the film forming chamber.

A piezoelectric element holder in which a plurality of piezoelectric elements are arranged in the circumferential direction around a predetermined axis, one main surface of each of the piezoelectric elements faces the bottom portion, and the plurality of piezoelectric elements are housed, and the bottom portion thereof. A piezoelectric element holder having an opening for introducing a film-forming material formed at a position where any one of the plurality of piezoelectric elements accommodated faces the piezoelectric element.
A rotation driving unit that rotates the plurality of piezoelectric elements around the predetermined axis in the piezoelectric element holder.
Based on the parameters of the equivalent circuit set in advance, the replacement time of the piezoelectric element facing the opening is determined, and when it is determined that the replacement time is reached, the rotation drive unit is used to connect the plurality of piezoelectric elements. A first control unit, which is rotated about 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, is further provided. Prepare,
The output unit may output a measurement signal whose frequency changes within a predetermined range to the piezoelectric element facing the opening.

The film forming apparatus according to the second aspect of the present invention is
With the film thickness monitoring device
A thin-film deposition source that evaporates the film-forming material to be formed on the object to be deposited,
Based on the resonance frequency of the piezoelectric element, the film formation rate of the film to be filmed on the object to be deposited is obtained, and the film deposition rate is within a preset film formation rate. It is characterized by comprising a second control unit for controlling the evaporation rate of the film-forming material evaporating from the source.

The film thickness monitoring method according to the third aspect of the present invention is
Using the piezoelectric element placed in the same film formation chamber as the film formation target placed in the film formation chamber, the film thickness of the film formed on the film formation target to be film-formed is determined. It is a film thickness monitoring method to monitor.
An output process that outputs a measurement signal whose frequency changes within a predetermined range to the piezoelectric element, and
A receiving step of receiving the measurement signal and the reflected signal reflected by the piezoelectric element from the measurement signal.
Based on the received measurement signal and the reflection signal, the impedance of the piezoelectric element is measured for each changing frequency, and the resonance frequency of the piezoelectric element is determined based on the measured impedance . A monitoring step of monitoring the film thickness of the film formed on the object to be deposited based on the amount of change in the resonance frequency is provided.
In the monitoring step, the frequency band to be swept is shifted to the low frequency side in conjunction with the progress of the film forming process, the impedance is measured, and the resonance frequency is determined.
It is characterized by that.

According to the present invention, by detecting the frequency characteristic of the piezoelectric element without using an oscillator, it is possible to accurately monitor the film thickness to be formed on the object to be filmed.

It is a conceptual diagram of the film thickness apparatus including the film thickness monitoring apparatus which concerns on 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 structure of the film thickness monitoring apparatus. It is a functional block diagram of the film thickness monitoring device. It is a graph which shows the frequency characteristic of the impedance of the crystal oscillator, and the frequency characteristic of a phase. It is a figure which shows the impedance frequency characteristic for each film formation. 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 a CI value. It is another graph which shows the frequency characteristic of the impedance of the crystal oscillator and the frequency characteristic of a phase. It is a schematic diagram of the crystal oscillator holder of the film thickness monitoring apparatus which concerns on Embodiment 2. FIG. It is a functional block diagram of the film thickness monitoring device. It is a flowchart of a crystal oscillator exchange process. It is a flowchart of the crystal oscillator exchange process of the modification 1. It is a flowchart of the crystal oscillator exchange process of the modification 2. It is a graph used when determining the upper limit of a CI value. It is a flowchart of the film formation rate control process in the film formation apparatus which concerns on Embodiment 3. FIG.

Hereinafter, embodiments of the film thickness monitoring device according to the present invention will be specifically described with reference to the accompanying drawings. It should be noted that the embodiments described below are for illustration purposes only and do not limit the scope of the present invention. Therefore, those skilled in the art can adopt embodiments in which each or all of these elements are replaced with equivalent ones, but these embodiments are also included in the scope of the present invention.

(Embodiment 1)
The film thickness apparatus provided with 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 device 10, a crystal oscillator holder 20, a vapor deposition source 30, a substrate holder 40, and a first controller 50. , Equipped with.

The film forming apparatus 1 is an apparatus for heating a vapor-deposited raw material in a vacuum atmosphere and depositing the vapor-deposited raw material vaporized by the heating on a substrate to be film-deposited as a film. The film forming apparatus 1 includes a film forming chamber 2, and a crystal oscillator holder 20, a vapor deposition source 30, and a substrate holder 40 are housed 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, the film forming treatment by the vacuum vapor deposition method is applied, but the film forming method is not limited to the vacuum vapor deposition 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 to knock out the target atoms, and the atoms are used to form a substrate by sputtering. A film forming process may be applied.

The film thickness monitoring device 10 is a device that monitors the thickness of the film deposited on the substrate to be film-formed, and in the first embodiment, a network analyzer is used. Details of the film thickness monitoring device 10 will be described later.

The crystal oscillator holder 20 is a holder that holds the crystal oscillator 23, and is made of a conductive material such as metal.

A schematic diagram of the crystal oscillator holder 20 holding the crystal oscillator 23 is shown in FIG. The crystal oscillator holder 20 includes a holder body 21, a lid portion 22, and a spring electrode 26.

The holder 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 21b is a hole for introducing the film-forming material vaporized from the vapor deposition source 30 into the holder main body 21. The crystal oscillator 23 is held inside the holder body 21 in a state where the vapor deposition surface 23a, which is one of the main surfaces of the crystal oscillator 23, is arranged so as to face the bottom portion 21a.

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

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

A first electrode portion 24 is provided on the vapor-deposited surface 23a of the crystal oscillator 23, and a second electrode portion 25 is provided on the non-deposited surface 23b. The first electrode portion 24 has a function as a grounding electrode, and is grounded via any component of the film forming apparatus 1, for example, the holder main body 21. The second electrode portion 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 formed of a metal material. The spring electrode 26 is inserted between the crystal oscillator 23 and the lid portion 22, is compressed by the lid portion 22, and is housed in the holder main body 21. The spring electrode 26 has the flexibility to regulate the movement of the crystal oscillator 23 in the holder body 21 and to allow the vibration of the crystal oscillator 23.

When the crystal oscillator 23 is housed 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 thin-film deposition source 30 is a device that heats the film-forming material filled in the crucible to vaporize 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 thin-film deposition source 30 is installed at the bottom of the film-forming chamber 2, and the crystal oscillator holder 20 is arranged at a position facing the direction in which the film-forming material of the vapor deposition source 30 evaporates.

The substrate holder 40 is a member that holds the substrate 41 to be film-formed. The vapor-deposited 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 vaporized film-forming material is vapor-deposited on the vapor-deposited surface.

The first controller 50 controls the operation of the vapor deposition source 30 and the film thickness monitoring device 10. It is composed of a processor, a memory, and the like, and stores the control program of the film forming apparatus 1 in the memory. The first controller 50 controls the entire film forming apparatus 1 according to this control program.

Next, the details of the film thickness monitoring device 10 will be described with reference to FIGS. 3 and 4. The basic configuration of the film thickness monitoring device 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, which is a measurement signal, to the crystal oscillator 23 to be measured. The signal source 11 is capable of frequency sweeping and can change the frequency of the generated sinusoidal signal within a predetermined range.

The signal distributor 12 is a device that distributes the sine wave signal transmitted by the signal source 11 into an input signal input to the crystal oscillator 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 oscillator 23 and a reflected signal reflected from the crystal oscillator 23. In the first embodiment, a directional coupler is used as the signal separator 13. The signal separator 13 may be a device capable of separating an input signal and a reflected signal, and may use, for example, an SWR bridge.

The receiver 14 receives a sine wave signal which is a reference signal distributed by the signal distributor 12 and a reflected signal 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. Further, the receiver 14 transmits the received signal to the second controller 15.

The second controller 15 obtains the resonance frequency and the parameters of the equivalent circuit of the crystal oscillator 23 from the frequency characteristics of the impedance of the crystal oscillator 23 based on the signal transmitted from the receiver 14. The film thickness of the film-forming material deposited on the crystal unit 23 is calculated from the amount of change in the detected resonance frequency. The second controller 15 calculates the film thickness of the film-forming material deposited on the substrate 41 and the film-forming rate, which is the amount of change in the film thickness per unit time, from the film thickness of the film-forming material deposited on the crystal oscillator 23. do. In order to convert the film thickness of the film-forming material deposited on the crystal oscillator 23 to the film thickness of the film-forming material deposited on the substrate 41, a process such as multiplying by a correction coefficient may be performed. The second controller 15 is composed of a processor, a memory, and the like, and stores the control program of 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 determined by the second controller 15, and includes a monitor. The display 16 may display the frequency characteristics of the impedance of the crystal oscillator 23, the resonance frequency, and the parameters of the equivalent circuit.

Next, the functional block diagram of the film thickness monitoring device 10 in 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 sinusoidal signal whose frequency changes within a predetermined range, to the crystal oscillator 23. The range of the changing frequency can be changed according to the type of the crystal oscillator 23 to be handled, and 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 divided into a reference signal and an input signal, and the input signal is input to the crystal oscillator 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. Further, the receiving unit 18 receives the reflected signal reflected by the crystal oscillator 23 with respect to the input signal. The receiver 14 functions as a receiver 18.

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

The frequency characteristic of the crystal oscillator 23 is determined from the phase difference and the amplitude ratio of both signals by comparing the input signal and the reflected signal. That is, by comparing the input signal and the reflected signal, the amplitude ratio and the phase difference are detected as the reflection characteristics. By converting this reflection characteristic into impedance, the magnitude and phase of impedance of the crystal oscillator 23 can be acquired. FIG. 5 is a graph in which the magnitude and phase of the impedance of the crystal oscillator 23 detected in this way are plotted for each changing frequency. FIG. 5 is a diagram showing the frequency characteristics of the magnitude of the impedance and the frequency characteristics of the phase created in this way . In FIG. 5, graph X is a graph showing a change in impedance magnitude with frequency, and graph Y is a graph showing a change in phase. From the graph shown in FIG. 5, the lowest frequency (point A) when the phase is zero is determined as the resonance frequency. The magnitude of impedance in the figure is indicated by Z.

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

The frequency characteristic of the impedance of the crystal oscillator 23 is obtained by gradually changing the frequency band to be swept during one film forming process and continuously obtaining it a plurality of times. FIG. 6 shows changes in the frequency characteristics of the impedance of the crystal unit 23 when the film formation process is performed. The sweep region is always selected to 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 unit. 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 in the front and back including the predicted value. By gradually shifting the sweep region, it is possible to constantly follow the series resonance due to the main vibration, so that the resonance frequency can be monitored without confusing the main vibration and the sub vibration.

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

FIG. 7 shows the impedance frequency characteristics of the main vibration and the secondary vibration. The vibration characteristic existing on the low frequency side in the figure is the main vibration, and the two vibration characteristics existing on the high frequency side are the secondary vibrations. Since the sub-vibration shown in the figure 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 discriminated from the frequency characteristic of the impedance, and the resonance frequency of the main vibration can be measured. The sub-vibration is a general term for all unnecessary vibrations that are not the main vibration, such as vibrations in different modes, contour slip vibrations, and bending vibrations.

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

The crystal oscillator 23 can be electrically displayed as an equivalent circuit shown in FIG. The equivalent circuit is composed of a series inductance L1, a series capacitance C1, a parallel capacitance C0, and a series resistance R1. The values indicated by L1, C1, C0, and R1 are one of the parameters of the equivalent circuit and can be used for monitoring the film thickness.

In the frequency characteristics of the crystal oscillator 23 shown in FIG. 5, the frequency of the point A (series resonance point) where the line of the graph X intersects the phase 0 ° portion of the graph Y is the series resonance frequency (simply in the present specification). It is described as a resonance frequency), and the frequency of the point B is also a parallel resonance frequency. By converting the amount of change in the resonance frequency into a film thickness and tracking the change, the film thickness of the film formed on the substrate 41 can be monitored.

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

Further, it is also possible to obtain the admittance, which is the reciprocal of the impedance, and obtain the parameters of the equivalent circuit of the crystal oscillator 23. The admittance (Y) can be displayed by the real part and the imaginary part of Y = G + jB (G: conductance, B: susceptance). By obtaining the frequency characteristic of the conductance of admittance, 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 oscillator, and the D value is the reciprocal of the Q value, which is a parameter indicating the energy loss of the crystal oscillator.

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

In addition, 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 unit 16. The user can predict the life of the crystal unit as a monitor by observing the change in the CI value displayed on the monitor.

A method of monitoring the film thickness in the film thickness monitoring device 10 having such a configuration will be described. The method is controlled and executed by 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 vapor deposition source 30 is heated and vaporized, and the film forming material is vapor-deposited on the vapor deposition surface of the substrate 41 to be deposited. Further, the vaporized film forming material is introduced from the opening 21b of the crystal oscillator holder 20 and adheres to the vapor deposition surface 23a of the crystal oscillator 23.

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

The receiver 14 (receiver 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) acquires the frequency characteristic of the impedance of the crystal oscillator 23 based on the received reference signal and the reflected signal, and determines the resonance frequency of the crystal oscillator. Then, the second controller 15 calculates the film thickness and the 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 thickness rate on the monitor of the display 16.

According to the first embodiment, the resonance frequency is detected based on the frequency characteristic of the impedance of the crystal oscillator 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 detected accurately without being affected by the secondary vibration. Further, since not only the resonance frequency but also the frequency characteristic of the impedance of the crystal oscillator can be detected, it can be used for the film formation rate control and the life management of the crystal oscillator.

According to the first embodiment, even when the sub-vibration occurs, the film formation rate can be controlled without being affected by the sub-vibration. For example, FIG. 10 shows the distortion of the waveform caused by the secondary vibration. As shown in FIG. 10, when affected by the secondary vibration, the waveform of the graph showing the frequency characteristic of the impedance fluctuates. In such a case, it is determined that the secondary vibration is generated from the distortion of the waveform, and the power of the vapor deposition source is controlled by using the control value calculated from the immediately preceding resonance frequency measurement value. The conventional crystal oscillation type film thickness monitoring method has a problem that the film formation rate becomes unstable by feeding back the fluctuation of the resonance frequency due to the secondary vibration to the film formation rate control. In No. 1, not only the resonance frequency but also the frequency characteristic of the impedance as shown in FIG. 10 can be acquired, so that it is possible to control to eliminate the influence of other vibration modes other than the main vibration.

According to the first embodiment, the resonance frequency of the crystal oscillator and the parameters of the equivalent circuit are obtained from the input signal and the reflected signal reflected by the input signal without using the passing signal that the input signal has passed through the crystal oscillator. I'm looking for it. Therefore, the first electrode portion 24 attached to the other main surface of the crystal oscillator 23 can be grounded, and the wiring structure can be simplified.

(Embodiment 2)
In the first embodiment, the film thickness monitoring device 10 using one crystal oscillator 23 has been described, but the present invention is not limited to using one crystal oscillator, and a plurality of crystal oscillators are used. It may be applied to a film thickness monitoring device that monitors the film thickness.

The film thickness monitoring device according to the second embodiment includes a film thickness monitoring device 100, a crystal oscillator 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 a film thickness monitoring device 100, a crystal oscillator holder 200, and a rotation drive mechanism 300 for rotating the crystal oscillator holder 200. Further, the crystal oscillator used is the same as the crystal oscillator 23 used in the first embodiment.

As shown in FIG. 11, the crystal oscillator 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 oscillator holder 200 includes a head portion 210, a holder main body 220, and a cover portion 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 thereof in the circumferential direction around the rotation shaft 201. The spring electrode 26 uses the same member as the spring electrode 26 applied in the first embodiment, and is fixed to the head portion 210 by the screw 26a.

The holder body 220 is a disk-shaped member made of a conductive material such as metal. The holder body 220 is arranged so as to face one end surface of the head portion 210 provided with the spring electrode 26. The bottom portion 220a of the holder body 220 is provided with a plurality of first openings 220b centered on a shaft coaxial with the rotation shaft 201. A plurality of crystal oscillators 23 are accommodated at positions corresponding to each of the plurality of first openings 220b, facing the head portion 210. Further, the holder main body 220 includes a cylindrical fitting portion 221 that protrudes from the center of the disk toward the head portion 210. The shaft end of the rotating shaft 201 of the head portion 210 is fitted to the cylindrical fitting portion 221, and the holder body 220 is attached to the head portion 210. Then, the holder body 220 is rotated coaxially with the rotation shaft 201 of the head portion 210.

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

The cover portion 230 is a disk-shaped cover that covers the holder body 220 from the bottom 220a side. The cover portion 230 corresponds to the bottom portion of the entire crystal oscillator holder 200. The cover portion 230 is formed with a second opening 231 formed to have the same diameter as the first opening 220b 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.

Further, the first electrode portion 24 attached to the main surface of the crystal oscillator 23 on the vapor deposition surface 23a side is grounded to the holder main 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 device 100 is the same as the basic configuration shown in FIG. 3, and the film thickness monitoring device 100 includes a signal source 11, a signal distributor 12, a signal separator 13, a receiver 14, and a second controller. 15. The display 16 is provided. The description of each configuration is omitted.

A functional block diagram of the film thickness monitoring device 100 is shown in FIG. The film thickness monitoring device 100 includes a first control unit 140, a rotation drive unit 150, an output unit 160, a reception unit 170, and a monitoring unit 180. Since 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 shown in FIG. 4, the description thereof will be omitted.

The first control unit 140 determines the life of the crystal oscillator 23, and when it is determined that the life has expired, the rotation drive unit 150 rotates the holder body 220 of the crystal oscillator holder 200 around the rotation shaft 201. To control. The second controller 15 of the film thickness monitoring device 100 functions as the first control unit 140.

The rotation drive unit 150 receives a signal from the first control unit 140 indicating that the crystal oscillator 23 has reached the end of its life, and rotates the holder body 220 of the crystal oscillator holder 200 about the rotation axis 201. .. The rotation drive mechanism 300 functions as the rotation drive unit 150.

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

A method of exchanging the crystal oscillator 23 while monitoring the film thickness in the film thickness monitoring device 10 having such a configuration will be described with reference to the flowchart shown in FIG.

First, the film formation process is actually performed to actually measure the CI value, and the upper limit of the CI value is set based on the measured value (step S1001). Specifically, the film formation rate and the CI value are obtained each time the film formation process is applied to the substrate, and the upper limit of the CI value is set based on the results. FIG. 16 is a graph showing the relationship between the CI value and the film formation rate when a plurality of films are laminated on the substrate 41 to form a film. The solid line shows the film formation rate for each film, and the broken line shows the CI value. The first film, the second film, and the eighth film are laminated on the substrate 41 one by one, and a plurality of film forming layers are vapor-deposited. As shown in FIG. 16, when the film forming process is executed from the first film to the eighth film, the waveform indicating the film forming rate is disturbed from the time when the sixth film is formed, and the film forming rate is not high. 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 first control unit 140 obtains the CI value before forming a film on the substrate 41 (step S1002). Specifically, the CI value is obtained by acquiring the frequency characteristic of the impedance of the crystal oscillator 23 using a measuring device such as a network analyzer.

Next, the first control unit 140 predicts the CI value after film formation based on the 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 oscillator 23 has expired.

When the first control unit 140 determines that the life of the crystal oscillator 23 has expired, the first control unit 140 instructs the rotation drive unit 150 to rotate the holder body 220 of the crystal oscillator holder 200 in a predetermined direction by a predetermined angle. do. Specifically, in the rotation drive mechanism 300, the unused crystal oscillator 23 arranged next to the crystal oscillator 23 determined to have reached the end of its life faces the second opening 231 of the cover portion 230. The holder body 220 is rotated so that the crystal oscillator is switched (step S1005). After the switching to the unused crystal oscillator 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 vapor deposition source 30 is heated and vaporized, and the film forming material is vapor-deposited on the vapor deposition surface of the substrate 41 to be deposited. On the other hand, with respect to the holder main body 220 and the cover portion 230, one of a plurality of crystal oscillators housed in the holder main body 220 has a second opening 231 of the cover portion 230 via the first opening 220b. It is arranged so as to correspond to. 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-deposited surface 23a of the crystal oscillator 23.

Further, 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, and 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 oscillator 23. Will be distributed. A part of the input signal input to the crystal oscillator 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 acquires the frequency characteristic of the impedance of the crystal oscillator 23 based on the reference signal and the reflected signal, and obtains the resonance frequency of the crystal oscillator 23 and the parameters of the equivalent circuit. 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 monitoring is performed. Also starts (step S1007).

Then, by monitoring the film thickness by the monitoring unit 180, it is determined whether or not the film forming process is completed (step S1008), and if the film forming process is completed (step S1008: YES), the process is completed. do. When the film forming process is not completed (step S1008: NO), the CI value before the film forming is measured (step S1002) before the next film forming process is started, and the same process is repeated. Here, "the film forming process is completed" includes the case where it is determined that the film thickness has reached a predetermined level, or the case where it is determined that all the films have been formed when a plurality of films are laminated.

(Modification 1)
In the flowchart shown in FIG. 13, it is determined whether or not the crystal oscillator 23 needs to be replaced before the film formation starts, but the crystal oscillator 23 may be replaced while monitoring the CI value during the film formation process. An example of performing film formation while monitoring the CI value will be described with reference to the flowchart shown in FIG.

First, the upper limit of the CI value is set in the same manner as in the case of determining whether or not the crystal oscillator 23 needs to be replaced before the start of film formation (step S1101).

Next, the film forming process on the substrate 41 is started (step S1102), and the first control unit 140 acquires the CI value from the frequency characteristic of the impedance of the crystal oscillator 23 during the film forming (step S1103). , It is determined whether or not the measured CI value is larger than the upper limit CI value (step S1104). When the 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 oscillator 23 has expired.

When the first control unit 140 determines that the life of the crystal oscillator 23 has expired, the film forming is stopped (step S1105), and the crystal oscillator holder 200 is operated to switch to the unused crystal oscillator 23. (Step S1106). After the switching to the unused crystal oscillator 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 thickness stop determination (step S1104), the film thickness monitoring (step S1107), and the film thickness process end determination (step S1108) are repeated to form a film. If the process is completed (step S1108: YES), the process is terminated.

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

In the flowchart shown in FIG. 14, when the measured CI value is larger than the upper limit CI value, the film formation is stopped, but the film formation is not stopped, the immediately preceding vapor deposition source power is maintained, and the film formation is continued. You may let me. 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 completed at the same time as the calculated time elapses.

According to the first modification, the upper limit of the CI value is set and the CI value is measured while forming a film, so that the life of the crystal oscillator is longer than that in the case of predicting the CI value and replacing the crystal oscillator. Can be extended.

(Modification 2)
In the first modification, one upper limit of the CI value is set to determine the replacement time of the crystal oscillator. 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 oscillator can be set. It is possible to delay and extend the life of the crystal unit.

In this modification, three upper limit values are set as the upper limit values of the CI value. As shown in FIG. 16, the CI value increases as the film thickness increases, causing disturbance in the film formation rate. In the second embodiment, as shown in FIG. 16, the value of the CI value when the sixth film in which the disturbance of the film forming rate is increasing is being formed is used as the upper limit value for replacing the crystal oscillator. I set it.

On the other hand, the CI value may temporarily rise under the influence of temperature and secondary vibration to indicate the value of the CI value which is the upper limit value, and when these influences disappear, it may show a change of falling below the upper limit value. be. In such a case, if it is determined that the CI value has increased and feedback is applied 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, so the film formation rate. It becomes difficult to control.

In this modification, the upper limit of the CI value specified in FIG. 16 is set as the first upper limit, and the waveform of the film formation rate in the eighth film of FIG. 16 is greatly disturbed, which has a fatal effect on the film formation process. The CI value giving the above was set as the third upper limit value. Then, the 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 of the three CI values has a relationship of <first upper limit value <second upper limit value <third upper limit value.

Then, 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 the crystal unit. After that, when the CI value becomes equal to or less 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 being formed at that time is completed. Then replace the crystal unit. If the CI value is larger than the third upper limit value, the film formation is immediately stopped and the crystal unit is replaced.

Such a crystal oscillator 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 by using the graph shown in FIG. 16, and the value between the first upper limit value and the third upper limit value is set as the second upper limit value. It is set as an upper limit value (step S1301). Then, the 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 showing the film formation rate.

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

If the CI value is equal to or less than the first upper limit value and it is determined that the film formation of the layer being filmed is not completed (step S1307; NO), the first control unit 140 again determines the CI value. If it is determined that the CI value is 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). , Maintain the power of the vapor deposition source immediately before and continue the film formation process. By performing such a process, when the CI value temporarily rises 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 forming process of the layer being filmed is completed (step S1307). Then, when it is determined that the film forming process of the layer being filmed is completed (step S1307; YES), it is determined whether all the film forming is completed (step S1308). When it is determined that all the film formations have been completed (step S1308; YES), the process is terminated. If it is determined that all the film formations have 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, and even if the film formation rate control is turned off, the CI value is measured again (step S1303), and the value is equal to or less than the first upper limit value. If it is determined to be present (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 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). The film formation process is continued with the vapor deposition source power constant until the film formation of the layer being filmed is completed (step S1314). Then, when all the film formation is completed (step S1315; YES), the process is completed. If all the film formations have not been completed (step S1315; NO), the crystal oscillator 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 secondary vibration on the film formation rate can be eliminated as much as possible. Further, since the crystal oscillator 23 continues to be used until the film formation of the layer being filmed is completed, the life of the crystal oscillator 23 can be extended.

When the CI value is equal to or higher than the third upper limit value (step S1318; YES), the film forming process is immediately stopped (step S1319), and the crystal oscillator 23 is replaced (step S1316). When the CI value is equal to or less than the third upper limit value (step S1318; NO), it is synonymous with the fact that the CI value is smaller than the first upper limit value, so the film formation 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 of the secondary vibration and the temperature on the CI value, which are factors other than the film thickness, and the crystal vibration can be formed. The period of use of the child can be further extended as compared with the first modification.

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

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

In the second embodiment, the second controller 15 is configured to function as the first control unit 140, but 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 oscillator holder 200 so that the unused crystal oscillator arranged next to the crystal oscillator that has reached the end of its life is in a used state. , It does not have to be the crystal oscillator placed next to it to be moved. If the adjacent crystal oscillator is not ready for use due to a defective product or the like, another unused crystal oscillator 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 oscillator has been described, but the method of obtaining the upper limit CI value in advance can also be applied to the first embodiment. Specifically, the upper limit CI value may be set in advance so that the user can confirm the CI value displayed on the monitor and predict the replacement time of the crystal unit. Further, when the CI value becomes close to the upper limit, a warning or the like may be displayed on the monitor to urge the user to replace the crystal oscillator 23.

According to the second embodiment, since the film thickness monitoring device 10 employs a monitoring method by a reflection method in which a measurement signal whose frequency is swept is applied and a reflected signal is received, one of the crystal oscillators 23 is used. The first electrode portion 24 attached to the main surface of the above can be grounded. Therefore, the wiring structure can be simplified, and the film thickness can be monitored by adopting a crystal holder that can accommodate a plurality of crystal oscillators 23 and 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 oscillator 23 facing the second opening 231 is selected. The electrical length from the second electrode portion 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 for selecting the connection between the spring electrode 26 and the film thickness monitoring device 10. It differs depending on a plurality of paths as the number of openings 220b. Due to the difference in electrical length, there is a slight difference in the amount of change in the resonance frequency in the crystal oscillation type film thickness meter. According to the second embodiment, in order to calibrate the electric lengths of each of the plurality of paths before measuring the crystal oscillator 23, the difference in the electric lengths of the plurality of paths is canceled out, and the amount of change in the resonance frequency is accurately performed. Can be asked. When the crystal oscillation type film thickness monitoring method is adopted, the resonance frequency cannot be measured accurately due to the influence of different load capacitances for each of a plurality of crystal oscillators.

According to the second embodiment, if the upper limit CI value is set in advance and 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 oscillator. can. Therefore, it is possible to prevent the crystal oscillator from reaching the end of its life in the middle of film formation, reduce the work load on the user, and continuously monitor an appropriate film thickness.

(Embodiment 3)
In the first and second embodiments, the film thickness monitoring device for appropriately monitoring the film thickness has been described, but the film thickness is formed so as to be an appropriate film thickness based on the monitoring result of such a film thickness monitoring device. It is also possible to provide a film forming apparatus capable of controlling the process.

The third embodiment is an embodiment in which the film forming rate is controlled in order to perform the film forming process so as to have an appropriate film thickness. As the film forming apparatus used in the third embodiment, the film forming apparatus 1 shown in FIG. 1 is used, and the film thickness monitoring apparatus 1 includes a film thickness monitoring device 10, a vapor deposition source 30, and 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 differs depending on the film formation material when the film is formed by the vacuum vapor deposition method. For example, the film forming material having a low melting point and the 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. Further, since the film formation rate is not stable at the initial stage of the film formation process, it is necessary to confirm whether or not the film formation rate is stable. Therefore, controlling the film formation rate to a predetermined value is important in the film formation process.

A method of 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 vapor-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 the substrate 41 to start the film forming process (step S1202).

Then, the second control unit causes the film thickness monitoring device 10 to acquire the frequency characteristic of the impedance of the crystal oscillator 23 and obtain the resonance frequency. The film thickness monitoring device 10 converts the obtained change amount of the resonance frequency into the film thickness, converts the film thickness change amount per unit time into the film thickness rate, and transfers the value of the film thickness rate to the second control unit. Transmit (step S1203).

The second control unit compares the converted film formation rate with the preset film formation rate, and determines whether or not they are the same (step S1204). The second control unit maintains the evaporation rate of the vapor deposition source 30 if the converted film formation rate and the set film formation rate are the same (step S1204: YES), and must be the same. For example (step S1204: NO), the evaporation rate of the vapor deposition source 30 is controlled to be increased or decreased so as 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 change amount obtained by the film thickness monitoring device 10 (step S1207). If the film thickness is a predetermined value (step S1207: YES), the film forming process is completed. If the film thickness is not a predetermined one (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 resonance frequency change amount per unit time obtained by the film thickness monitoring device 10. In the third embodiment, if the resonance frequency having a phase of 0 ° can be obtained in the graph showing the frequency characteristics, it can be converted into the film formation rate. Therefore, the resonance frequency can be more reliably acquired than the resonance frequency measured by the crystal oscillation type film thickness monitoring method, and can be reflected in the film formation rate.

Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments described so far, and includes those with appropriate modifications.

In the first to third embodiments, the substrate holder 40 that holds one substrate 41 has been described as an example, but the present invention is not limited to such a substrate holder 40. For example, it is also applied when 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 oscillator having reached the end of its life will be described as being switched to a new crystal oscillator by the rotation drive mechanism 300 shown in FIG. 11 rotating the holder body 220. did. The present invention is not limited to such a switching mechanism of the crystal oscillator 23, and the crystal oscillator having reached the end of its life is individually replaced by an exchange device by using a crystal oscillator holder holding one crystal oscillator. You may.

In the second modification, three upper limit values of the CI value are set to determine the replacement time of the crystal oscillator, but the second upper limit value and the third upper limit value, or the first upper limit value and the first upper limit value and the second upper limit value are determined. It may be a combination of two upper limit values, that is, an upper limit value of 3. In the second modification, the control of the film formation rate is turned off when the CI value exceeds the first upper limit value, but the fluctuation of the CI value is predicted in advance, and the difference between the predicted CI value and the actually measured CI value is a predetermined value. When the above is achieved, the film formation rate control may be turned off. Alternatively, when the measured CI value fluctuation amplitude width becomes a predetermined width or more, the film formation rate control may be turned off.

INDUSTRIAL APPLICABILITY The present invention can be used as a film thickness monitoring device for monitoring the film thickness of a film formed on the surface of a substrate by a film forming process.

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

Claims (11)

Using the piezoelectric element placed in the same film formation chamber as the film formation target placed in the film formation chamber, the film thickness of the film formed on the film formation target to be film-formed is determined. It is a film thickness monitoring device that monitors
An output unit that outputs a measurement signal whose frequency changes within a predetermined range to the piezoelectric element, and
A receiving unit that receives the measurement signal and a reflection signal obtained by reflecting the measurement signal by the piezoelectric element.
The impedance of the piezoelectric element for each changing frequency was measured based on the received measurement signal and the reflected signal, and the resonance frequency of the piezoelectric element was determined based on the measured impedance . A monitoring unit for monitoring the film thickness of the film formed on the object to be deposited based on the amount of change in the resonance frequency is provided.
The monitoring unit shifts the frequency band to be swept to the low frequency side in conjunction with the progress of the film forming process, measures the impedance, and determines the resonance frequency.
A film thickness monitoring device characterized by this. The monitoring unit predicts the next resonance frequency based on the resonance frequency and the film formation rate determined by the swept frequency band, and determines the frequency band including the predicted resonance frequency as the next frequency band to be swept. do,
The film thickness monitoring device according to claim 1. The output unit is
A signal distributor that distributes the measurement signal into an input signal and a reference signal and inputs the input signal to the piezoelectric element.
Includes a signal separator that separates the input signal from the reflected signal reflected by the piezoelectric element.
The receiving unit receives the reference signal distributed by the signal distributor and the reflected signal separated by the signal separator.
The monitoring unit acquires the frequency characteristics of the impedance of the piezoelectric element based on the received reference signal and the reflected signal for each changing frequency , and the piezoelectric element is based on the frequency characteristics of the acquired impedance. The resonance frequency of the ,
The film thickness monitoring device according to claim 1 or 2 . The monitoring unit monitors the life of the piezoelectric element based on the determined parameters of the equivalent circuit.
The film thickness monitoring device according to claim 3 . The monitoring unit sweeps a frequency band in a preset range including the resonance frequency of the piezoelectric element, and determines the resonance frequency of the piezoelectric element and the parameters of the equivalent circuit from the frequency characteristics of the impedance of the piezoelectric element. To do ,
The film thickness monitoring device according to any one of claims 1 to 4, wherein the film thickness monitoring device is characterized. The piezoelectric element is a crystal oscillator and is
The parameter of the equivalent circuit of the crystal oscillator is crystal impedance.
The film thickness monitoring device according to any one of claims 3 to 5 , wherein the film thickness monitoring device is characterized. In the piezoelectric element, a pair of electrodes are installed on both main surfaces facing each other, the electrode installed on one main surface of the piezoelectric element is grounded, and the electrode installed on the other main surface is connected to the output unit. Be done,
The film thickness monitoring device according to any one of claims 1 to 6 , wherein the film thickness monitoring device is characterized. The electrode installed on one main surface of the piezoelectric element was grounded to a component of the film forming chamber.
The film thickness monitoring device according to claim 7. A piezoelectric element holder in which a plurality of piezoelectric elements are arranged in the circumferential direction around a predetermined axis, one main surface of each of the piezoelectric elements faces the bottom portion, and the plurality of piezoelectric elements are housed, and the bottom portion thereof. A piezoelectric element holder having an opening for introducing a film-forming material formed at a position where any one of the plurality of piezoelectric elements accommodated faces the piezoelectric element.
A rotation driving unit that rotates the plurality of piezoelectric elements around the predetermined axis in the piezoelectric element holder.
Based on the parameters of the equivalent circuit set in advance, the replacement time of the piezoelectric element facing the opening is determined, and when it is determined that the replacement time is reached, the rotation driving unit is used to connect the plurality of piezoelectric elements. A first control unit, which is rotated about 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, is further provided. Prepare,
The output unit outputs a measurement signal whose frequency changes within a predetermined range to a piezoelectric element facing the opening.
The film thickness monitoring device according to any one of claims 1 to 8 , wherein the film thickness monitoring device is characterized. The film thickness monitoring device according to any one of claims 1 to 9 , and the film thickness monitoring device.
A thin-film deposition source that evaporates the film-forming material to be formed on the object to be deposited,
Based on the resonance frequency of the piezoelectric element, the film formation rate of the film to be deposited on the object to be deposited is obtained, and the vaporization is performed so that the film formation rate is within the preset film formation rate. A second control unit for controlling the evaporation rate of the film-forming material evaporating from the source is provided.
A film forming apparatus characterized by this. Using the piezoelectric element placed in the same film formation chamber as the film formation target placed in the film formation chamber, the film thickness of the film formed on the film formation target to be film-formed is determined. It is a film thickness monitoring method to monitor.
An output process that outputs a measurement signal whose frequency changes within a predetermined range to the piezoelectric element, and
A receiving step of receiving the measurement signal and the reflected signal reflected by the piezoelectric element from the measurement signal.
Based on the received measurement signal and the reflection signal, the impedance of the piezoelectric element is measured for each changing frequency, and the resonance frequency of the piezoelectric element is determined based on the measured impedance . A monitoring step of monitoring the film thickness of the film formed on the object to be deposited based on the amount of change in the resonance frequency is provided.
In the monitoring step, the frequency band to be swept is shifted to the low frequency side in conjunction with the progress of the film forming process, the impedance is measured, and the resonance frequency is determined.
A film thickness monitoring method characterized by this.

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