JP6333386B2 - Quartz crystal replacement method and film thickness monitor - Google Patents

Description

  The present invention relates to a method for diagnosing a film thickness sensor having a vibrator and a film thickness monitor.

  2. Description of the Related Art Conventionally, in a film forming apparatus such as a vacuum evaporation apparatus, a method of measuring a small amount of mass change using a crystal resonator (QCM: Quartz Crystal) to measure the thickness and film forming speed of a film formed on a substrate. Microbalance) is used. This method makes use of the fact that the oscillation frequency of the crystal resonator disposed in the chamber decreases with an increase in mass due to the deposition of the vapor deposition material. Therefore, it is possible to measure the film thickness and the deposition rate by measuring the change in the oscillation frequency of the crystal resonator.

  On the other hand, when the film thickness is measured by QCM, if a thin film is formed on the quartz resonator, the oscillation of the quartz resonator becomes unstable due to peeling of the membrane or accumulation of internal stress. It becomes. In this state, it is no longer possible to perform an appropriate film thickness measurement. Therefore, when the above phenomenon occurs, it is necessary to determine that the crystal resonator is at the end of its life and switch to a new crystal resonator.

  For example, in Patent Document 1, when a holder that supports a plurality of crystal resonators is rotatably accommodated and the oscillation frequency of the crystal resonators deviates from a predetermined fluctuation allowable range, the crystal resonator has reached the end of its life. A sensor head configured to judge and rotate the holder to switch to a new crystal resonator is described (Patent Document 1, paragraph [0023]).

Japanese Patent No. 3953301

In this type of film thickness sensor, the change in the oscillation frequency of the crystal resonator differs significantly depending on whether the film forming material is a metal material or an organic material.
For example, in the case of a metal film, the oscillation frequency of the crystal resonator gradually decreases as the deposition amount increases, and suddenly changes greatly when the frequency reaches a predetermined frequency. Therefore, since the film thickness can be measured relatively stably until the sudden change in the oscillation frequency is confirmed, it is determined that the crystal unit cannot be used (ie, the life) when the sudden change in the oscillation frequency occurs. be able to.
On the other hand, in the case of an organic film, as the amount of deposited film increases, the oscillation frequency of the crystal resonator decreases, and at the same time, the frequency fluctuation increases so that stable film thickness measurement can no longer be performed. . Therefore, when the organic film is formed, the measurable film thickness is very small as compared with the case where the metal film is formed. For this reason, in order to carry out a stable film forming process, it is indispensable to determine a proper lifetime of the crystal resonator.

  In view of the circumstances as described above, an object of the present invention is to provide a film thickness sensor diagnostic method and film thickness monitor capable of performing an appropriate lifetime determination of a crystal resonator.

A method for diagnosing a film thickness sensor according to an aspect of the present invention is a method for diagnosing a film thickness sensor having a crystal resonator, and includes oscillating a crystal resonator mounted on a sensor head.
The fluctuation range of the change rate of the oscillation frequency of the crystal resonator is measured.
When the fluctuation range exceeds a predetermined value, it is determined that the crystal unit cannot be used.

  The film thickness and the film formation rate are proportional to the rate of change of the oscillation frequency of the crystal resonator. Therefore, the stable transition of the film formation rate means that the rate of change of the oscillation frequency of the crystal resonator is stable. On the other hand, when the crystal unit approaches the end of its life, the fluctuation range of the change rate of the oscillation frequency of the crystal unit increases. Therefore, in the above diagnostic method, by determining whether or not the lifetime of the crystal resonator is based on the fluctuation range of the change rate of the oscillation frequency of the crystal resonator (that is, the difference for each sampling of the oscillation frequency), Appropriate life judgment can be performed. As a result, the life of the crystal unit can be detected quickly, and deterioration of film thickness control due to the life of the crystal unit can be prevented.

  The predetermined value of the fluctuation range corresponds to a reference value for determining the lifetime of the crystal resonator (determining whether or not it can be used), and can be set as appropriate according to the purpose. The predetermined value may be, for example, a size that is considered to have reached the end of the life, or may be a predetermined size before it is considered that the end of the life has been reached. Alternatively, a plurality of the predetermined values may be set stepwise according to the magnitude of the fluctuation range.

  When the life of the crystal unit (unusable) is determined, an alarm (for example, display on the screen, ringing of buzzer, light emission of lamp) may be issued to prompt the user to replace the crystal unit. When a plurality of crystal resonators are provided, control for automatically switching to a new crystal resonator may be executed.

  The measurement of the fluctuation range may be performed at the time of film formation or may be performed at the time of non-film formation. The fluctuation range of the change rate of the oscillation frequency of a normal crystal resonator (a resonator that has not reached the end of life, the same applies hereinafter) is stable both during film formation and during non-film formation. For this reason, it is possible to determine the lifetime of the crystal resonator based on the fluctuation range measured during film formation or non-film formation.

  In the step of measuring the fluctuation range, a standard deviation of the fluctuation range of the change rate of the oscillation frequency in a certain period is measured. Thereby, while being able to reduce calculation load, a determination result can be acquired rapidly. The sample point is not particularly limited and can be set arbitrarily.

A film thickness monitor according to one embodiment of the present invention includes a sensor head and a measurement unit.
The sensor head includes a holder that supports the first and second crystal units and a casing that rotatably accommodates the holder.
The measurement unit is configured to measure each variation width of the change rate of the oscillation frequency of the first and second crystal resonators and determine that a crystal resonator having the variation width exceeding a predetermined value cannot be used. The

The casing typically has a window. The window portion is formed to face the first crystal unit and is configured to allow the vapor deposition material to pass therethrough. The measurement unit is configured to rotate the holder to a position where the second crystal resonator faces the window when the life of the first crystal resonator is determined.
Thereby, the vibrator for measuring the film thickness can be automatically switched from the first crystal oscillator to the second crystal oscillator.

  According to the present invention, it is possible to perform an appropriate life determination of a crystal resonator.

It is a schematic sectional drawing which shows the film-forming apparatus which concerns on one Embodiment of this invention. It is a schematic block diagram which shows one structural example of the measurement unit in the said film-forming apparatus. It is an experimental result which shows an example of measurement data when the film formation rate fluctuates greatly after the start of film formation and monitoring becomes impossible. It is an experimental result which shows an example of the change rate of the oscillation frequency of a crystal oscillator during film formation and during film formation (during substrate exchange). FIG. 5 is a partially enlarged view of measurement data when no film is formed in FIG. 4. FIG. 5 is a partially enlarged view of measurement data at the time of film formation in FIG. 4. It is one experimental result which shows the change rate of the oscillation frequency of the crystal resonator determined to have reached the lifetime. It is a schematic block diagram which shows the film thickness monitor which concerns on one Embodiment of this invention. It is a figure which shows the operation | movement procedure of the film-forming apparatus containing the example of 1 operation | movement of the said film thickness monitor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a schematic sectional view showing a film forming apparatus according to an embodiment of the present invention. The film forming apparatus 10 of this embodiment is configured as a vacuum vapor deposition apparatus.

  The film forming apparatus 10 includes a vacuum chamber 11, a vapor deposition source 12 disposed inside the vacuum chamber 11, a stage 13 facing the vapor deposition source 12, and a film thickness sensor 14 disposed inside the vacuum chamber 11. Have.

  The vacuum chamber 11 is connected to the evacuation system 15 and is configured to be able to maintain a predetermined reduced pressure atmosphere inside.

  The vapor deposition source 12 is configured to be capable of generating vapor (particles) of vapor deposition material. In the present embodiment, the vapor deposition source 12 is electrically connected to the power supply unit 18, and is an evaporation source that heats and evaporates the organic material (Alq3 (Tris (8-quinolinolato) aluminum)) to release organic material particles. Configure. The type of the evaporation source is not particularly limited, and various methods such as a resistance heating method, an induction heating method, and an electron beam heating method can be applied. The evaporation material may be an organic material other than those described above, or may be a metal material, a metal compound material, or the like.

  The stage 13 is configured to be able to hold a substrate W as a film formation target such as a semiconductor wafer or a glass substrate toward the vapor deposition source 12.

  The film thickness sensor 14 (sensor head) incorporates a crystal resonator having a predetermined fundamental frequency (natural frequency), and measures the film thickness and film formation rate of the organic film deposited on the substrate W, as will be described later. The sensor head for this is comprised. As the crystal resonator, for example, an AT-cut crystal resonator having relatively excellent temperature characteristics is used, and the predetermined fundamental frequency is typically 5 to 6 MHz, and in this embodiment, 5 MHz. . The film thickness sensor 14 is disposed inside the vacuum chamber 11 and at a position facing the vapor deposition source 12. The film thickness sensor 14 is typically disposed in the vicinity of the stage 13.

  The output of the film thickness sensor 14 is supplied to the measurement unit 17 (film thickness control device). The measurement unit 17 measures the film thickness and the film formation rate based on the change in the oscillation frequency of the crystal resonator, and controls the vapor deposition source 12 so that the film formation rate becomes a predetermined value. The film thickness sensor 14 and the measurement unit 17 constitute a “film thickness monitor” according to the present invention.

  The relationship between the frequency change due to the adsorption of the QCM and the mass load is the Sauerbrey equation expressed by the following equation (1).

In Equation (1), ΔFs is the amount of frequency change, Δm is the amount of mass change, f ₀ is the fundamental frequency, ρ _Q is the density of the crystal, μ _Q is the shear stress of the crystal, A is the electrode area, and N is a constant. ing.

  The film forming apparatus 10 further includes a shutter 16. The shutter 16 is disposed between the vapor deposition source 12 and the stage 13, and is configured to be able to open or shield the incident path of vapor deposition particles from the vapor deposition source 12 to the stage 13 and the film thickness sensor 14.

  Opening and closing of the shutter 16 is controlled by a control unit (not shown). Typically, the shutter 16 is closed at the start of vapor deposition until the release of vapor deposition particles at the vapor deposition source 12 is stable. And when discharge | release of vapor deposition particle is stabilized, the shutter 16 is open | released. Thereby, the vapor deposition particles from the vapor deposition source 12 reach the substrate W on the stage 13, and the film forming process of the substrate W is started. At the same time, the vapor deposition particles from the vapor deposition source 12 reach the film thickness sensor 14, and the measurement unit 17 monitors the film thickness of the vapor deposition film on the substrate W and its film formation rate.

Next, the measurement unit 17 will be described.
FIG. 2 is a schematic block diagram illustrating a configuration example of the measurement unit 17. The measurement unit 17 includes an oscillation circuit 41, a measurement circuit 42, and a controller 43.

  The oscillation circuit 41 oscillates the crystal resonator 20 of the film thickness sensor 14. The measurement circuit 42 is for measuring the oscillation frequency of the crystal resonator 20 output from the oscillation circuit 41. The controller 43 obtains the oscillation frequency of the crystal unit 20 through the measurement circuit 42 every unit time, and calculates the deposition rate of the deposition material particles on the substrate W and the thickness of the deposition film deposited on the substrate W. To do. The controller 43 further controls the vapor deposition source 12 so that the film formation rate becomes a predetermined value.

  The measurement circuit 42 includes a mixer circuit 51, a low pass filter 52, a low frequency counter 53, a high frequency counter 54, and a reference signal generation circuit 55. The signal output from the oscillation circuit 41 is input to the high frequency counter 54, and first, the approximate value of the oscillation frequency of the oscillation circuit 41 is measured. The approximate value of the oscillation frequency of the oscillation circuit 41 measured by the high frequency counter 54 is output to the controller 43. The controller 43 oscillates the reference signal generation circuit 55 at a reference frequency (for example, 5 MHz) that is close to the measured approximate value. A signal having a frequency oscillated at the reference frequency and a signal output from the oscillation circuit 41 are input to the mixer circuit 51.

  The mixer circuit 51 mixes the two types of input signals and outputs the mixed signals to the low frequency counter 53 via the low pass filter 52. Here, if the signal input from the oscillation circuit 41 is cos ((ω + α) t) and the signal input from the reference signal generation circuit is cos (ωt), cos (ωt) · cos ( An AC signal expressed by the equation (ω + α) t) is generated. This equation is in the form of multiplying cos (ωt) and cos ((ω + α) t), and the AC signal represented by this equation is a high frequency component represented by cos ((2 · ω + α) t). And a low frequency component signal represented by cos (αt).

  The signal generated by the mixer circuit 51 is input to the low-pass filter 52, the high-frequency component signal cos ((2 · ω + α) t) is removed, and only the low-frequency component signal cos (αt) is input to the low-frequency counter 53. Entered. That is, the low frequency counter 53 has a low frequency component that is an absolute value | α | of the frequency difference between the signal cos ((ω + α) t) of the oscillation circuit 41 and the signal cos (ωt) of the reference signal generation circuit 55. Signal is input.

  The low frequency counter 53 measures the frequency of the low frequency component signal and outputs the measured value to the controller 43. The controller 43 calculates the frequency of the signal output from the oscillation circuit 41 from the frequency measured by the low frequency counter 53 and the frequency of the output signal of the reference signal generation circuit 55. Specifically, when the frequency of the output signal of the reference signal generation circuit 55 is smaller than the frequency of the output signal of the oscillation circuit 41, the frequency of the low frequency component signal is added to the output signal of the oscillation circuit 41, In the opposite case, subtract.

  For example, when the measured value of the oscillation frequency of the oscillation circuit 41 by the high frequency counter 54 exceeds 5 MHz and the reference signal generation circuit 55 is oscillated at a frequency of 5 MHz, the oscillation frequency of the reference signal generation circuit 55 is It becomes lower than the actual oscillation frequency of the circuit 41. Therefore, in order to obtain the actual oscillation frequency of the oscillation circuit 41, the frequency | α | of the low-frequency component signal obtained by the low-frequency counter 53 may be added to the set frequency 5 MHz of the reference signal generation circuit 55. If the frequency | α | of the low frequency component is 10 kHz, the accurate oscillation frequency of the oscillation circuit 41 is 5.01 MHz.

  Although the resolution of the low-frequency counter 53 has an upper limit, the resolution can be assigned to measure the difference frequency | α |, and therefore, compared with the case of measuring the oscillation frequency of the oscillation circuit 41 with the same resolution. Accurate frequency measurement can be performed.

  The oscillation frequency of the reference signal generation circuit 55 is controlled by the controller 43, and the oscillation frequency can be set so that the difference frequency | α | is smaller than a predetermined value. Can be effectively utilized. The obtained frequency value is stored in the controller 43. The controller 43 calculates the film thickness and film formation rate of the vapor deposition material deposited on the substrate W from the obtained frequency value using the arithmetic expression shown by the above expression (1).

  Typically, the controller 43 can be realized by hardware elements used in a computer such as a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory) and necessary software. Instead of or in addition to the CPU, a PLD (Programmable Logic Device) such as an FPGA (Field Programmable Gate Array) or a DSP (Digital Signal Processor) may be used.

[Crystal resonator life determination]
By the way, when this type of film thickness sensor is used to form an organic film, the oscillation frequency of the crystal unit gradually decreases as the amount of deposited film increases, and at the same time, a stable film thickness measurement can be performed. The frequency fluctuation becomes so large that it cannot be done. Therefore, when the organic film is formed, the measurable film thickness is very small as compared with the case where the metal film is formed. For this reason, in order to carry out a stable film forming process, it is indispensable to determine a proper lifetime of the crystal resonator.

  On the other hand, a method for measuring the equivalent resistance of a crystal resonator is known as a method for determining the lifetime (replacement time) of the crystal resonator. In this method, when the equivalent resistance exceeds a predetermined value, the crystal resonator is considered to have reached the end of life. For example, the predetermined value in a crystal resonator having a fundamental frequency of 5 MHz is set to 20Ω. A method of measuring the current flowing through the crystal resonator is also known, but this method is synonymous with measuring the equivalent resistance of the crystal resonator because the voltage applied to the crystal resonator is constant.

  However, according to experiments by the present inventor, it has been confirmed that the equivalent resistance of the crystal resonator has no correlation with the defect or life of the crystal resonator. FIG. 3 shows an example of measurement data when the film formation rate fluctuates greatly after the start of film formation and monitoring is no longer possible. The equivalent resistance of the quartz resonator at this time was measured and found to be 15.2Ω, which was within the range considered normal (20Ω or less).

  In this embodiment, when determining the lifetime (replacement time) of the crystal resonator, the variation width of the change rate of the oscillation frequency is used as a reference, not the equivalent resistance of the crystal resonator. In other words, the film thickness sensor diagnosis method according to the present embodiment oscillates the crystal resonator 20 and measures the variation width of the change rate of the oscillation frequency of the crystal resonator 20, and when the variation width exceeds a predetermined value, The crystal unit 20 is determined to have a lifetime (cannot be used).

  The film thickness and the film formation rate are proportional to the rate of change of the oscillation frequency of the crystal resonator 20. Therefore, the stable transition of the deposition rate means that the rate of change of the oscillation frequency of the crystal resonator 20 is stable. On the other hand, when the crystal unit 20 approaches the end of its life, the fluctuation range of the change rate of the oscillation frequency of the crystal unit 20 increases. Therefore, in the present embodiment, the crystal oscillation is determined by determining whether or not the lifetime of the crystal resonator 20 is based on the fluctuation range of the change rate of the oscillation frequency of the crystal resonator 20 (that is, the difference for each sampling of the oscillation frequency). An appropriate life determination of the child 20 can be performed. As a result, the life of the crystal unit 20 can be detected quickly, and deterioration of the film thickness control due to the life of the crystal unit 20 can be prevented.

  The lifetime determination of the crystal unit 20 described above is performed by the controller 43 in the measurement unit 17. The controller 43 calculates the fluctuation range (Δ2F) of the change rate (ΔF) of the oscillation frequency (F) of the crystal resonator 20 measured in the measurement circuit 42, and whether or not the fluctuation range (Δ2F) exceeds a predetermined value. When the fluctuation range (Δ2F) exceeds a predetermined value, the crystal unit 20 is configured to be determined to have a lifetime.

  The predetermined value corresponds to a reference value for determining the life of the crystal unit 20 and can be appropriately set according to the purpose. In the present embodiment, the predetermined value is set to 0.1 Hz, for example. The predetermined value may be, for example, a size that is considered to have reached the end of the life, or may be a predetermined size before it is considered that the end of the life has been reached. Alternatively, a plurality of the predetermined values may be set stepwise according to the magnitude of the fluctuation range.

  In the step of measuring the fluctuation range (ΔF2) of the frequency change rate of the crystal unit 20, the standard deviation of the change rate of the oscillation frequency in a certain period may be measured. Thereby, while being able to reduce calculation load, a determination result can be acquired rapidly. The sample point is not particularly limited and can be set arbitrarily. In this case, when the standard deviation exceeds a predetermined value, it is determined that the lifetime of the crystal unit 20 is reached. The predetermined value of the standard deviation is, for example, 0.1 Hz.

  When the life of the crystal unit 20 is determined, the controller 43 is configured to, for example, issue an alarm (for example, display on a screen, sound of a buzzer, light emission of a lamp) that prompts the user to replace the crystal unit 20. Is done. Alternatively, when the film thickness sensor 14 includes a plurality of crystal resonators, the controller 43 may be configured to automatically perform control to switch to a new crystal resonator, as will be described later.

  The measurement of the fluctuation range of the oscillation frequency of the crystal unit 20 may be performed during film formation or may be performed during non-film formation. FIG. 4 is an experimental result showing an example of a change rate (ΔF) of the oscillation frequency of the crystal resonator 20 during film formation and during non-film formation (during replacement of the substrate W). Alq3 (tris (8-quinolinolato) aluminum) was used as the vapor deposition material.

  As shown in FIG. 4, the frequency change rate (ΔF) in the normal crystal unit 20 is stable at an almost constant value regardless of whether the film is formed or not. Therefore, it is possible to determine the life of the crystal unit 20 based on the fluctuation width (Δ2F) of the frequency change rate during film formation or during non-film formation.

  FIG. 5 is a partially enlarged view of measurement data when not forming a film in FIG. 4, and FIG. 6 is a partially enlarged view of measurement data when forming a film in FIG. As shown in FIGS. 5 and 6, the fluctuation width (Δ2F) of the change rate of the oscillation frequency is kept within 0.03 Hz during non-film formation and during film formation. In the illustrated example, the standard deviation of the fluctuation range (Δ2F) was 0.005 Hz for both the non-film formation and the film formation.

  On the other hand, FIG. 7 shows one measurement data indicating the rate of change (ΔF) of the oscillation frequency of the crystal resonator 20 determined to have reached the end of its life. The fluctuation range (Δ2F) at this time was 2 Hz, and the standard deviation was 0.5 Hz.

  As described above, according to the present embodiment, for example, by calculating the fluctuation width (ΔF2) of the oscillation frequency change rate or its standard deviation before or during film formation, the crystal resonator 20 has a defect or life ( The replacement time can be determined appropriately and easily. In particular, the lifetime of the crystal unit 20 can be quickly determined when forming an organic film that reaches the end of its life relatively early.

  In addition, instead of measuring the fluctuation range (Δ2F) of the oscillation frequency change rate of the crystal unit 20 or its standard deviation, it is possible to determine the life of the crystal unit 20 based on the fluctuation range of the film formation rate. However, since the film formation rate is converted to the film thickness from the frequency change and the density of the vapor deposition material, and more often multiplied by a correction coefficient related to the sensor position with respect to the substrate, from the viewpoint of determining the lifetime of the crystal unit, It is more essential to look at the fluctuation of the frequency change rate of the crystal unit itself.

<Second Embodiment>
Subsequently, another embodiment of the present invention will be described. Hereinafter, configurations different from those of the first embodiment will be mainly described, and configurations similar to those of the above-described embodiment will be denoted by the same reference numerals, and description thereof will be omitted or simplified.

  FIG. 8 is a schematic configuration diagram showing the film thickness monitor 100 according to the present embodiment. The film thickness monitor 100 includes a film thickness sensor 140 (sensor head) and a measurement unit 17.

  The film thickness sensor 140 includes a holder 141 that can support a plurality of crystal resonators (12 in this example) 201 to 212 and a casing 142 that rotatably accommodates the holder 141.

  The holder 141 has a disk shape, and the plurality of crystal resonators 201 to 212 are mounted near the periphery of the holder 141 at equal angular intervals. The holder 141 is configured to be able to rotate intermittently at the same angular interval in the direction of the arrow in the figure inside the casing 142.

  The casing 142 includes a rotation shaft 142a that rotatably supports the holder 141, and a drive mechanism (not shown) that rotates the holder 141 around the rotation shaft 142a. The drive mechanism is configured to rotate the holder 141 by a predetermined angle in the direction of the arrow in the figure in accordance with a control signal input from the measurement unit 17.

  The casing 142 includes a window portion 143 that exposes only one crystal resonator to the outside (deposition source 12) among the plurality of crystal resonators 201 to 212 attached to the holder 141. In the illustrated example, the crystal unit 201 is exposed through the window portion 143.

  Further, the casing 142 is provided with an electrode unit 144 for electrically connecting the crystal resonator at the rotational position of the window portion 143 to the measurement unit 17. The electrode unit 144 is disposed in the vicinity of the window portion 143 and is configured to come into contact with the crystal resonator that has been moved to a position facing the window portion 143 by the rotation of the holder 141.

  FIG. 9 shows an operation procedure of the film forming apparatus including an operation example of the film thickness monitor 100.

  First, before the film formation, the twelve crystal resonators 201 to 212 are mounted on the holder 141 of the film thickness sensor 140 (step 101). Typically, the quartz vibrators 201 to 212 are the same kind of quartz vibrator.

  Subsequently, the quality of the oscillation operation is determined for all of the crystal resonators 201 to 212 (step 102). In this process, the holder 141 is intermittently rotated to connect all the crystal oscillators 201 to 212 to the electrode unit 144 in order, and the measurement unit 17 oscillates each oscillator for a predetermined time with a predetermined drive voltage. At this time, the measurement unit 17 measures the fluctuation range of the change rate of the oscillation frequency of the crystal resonator, and determines that the crystal resonator that exceeds a predetermined value is defective. The crystal resonator determined to be defective is replaced with another new crystal resonator (step 103).

  The quality determination of the crystal resonators 201 to 212 is a preliminary one for confirming the characteristics of the crystal resonators 201 to 212, and can be omitted as necessary. According to the present embodiment, as described in the first embodiment, the fact that the rate of change of the oscillation frequency of the crystal resonator during non-film formation is stable is utilized. On the basis of the standard deviation, the quality of the oscillation operation of each of the crystal units 201 to 212 is determined.

  Next, referring to FIG. 1, the substrate W is placed on the stage 13, the vapor deposition material is supplied to the vapor deposition source 12, and then the vacuum chamber 11 is exhausted to a predetermined reduced pressure atmosphere by the vacuum exhaust system 15. Then, the shutter 16 is opened, and deposition of a vapor deposition material on the substrate W is started (step 104). At this time, the film thickness monitor 100 monitors the film thickness and film formation rate of the vapor deposition material deposited on the surface of the substrate W using the crystal unit 201.

  The controller 43 of the measurement unit 17 measures the fluctuation range of the change rate of the oscillation frequency of the crystal resonator 201 during film formation, so that the crystal resonator can reach the end of its life in the same manner as in the first embodiment. It is determined whether or not it has been reached (step 105). When the controller 43 determines that the crystal resonator 201 has not reached the end of its life, the controller 43 continues oscillation.

  On the other hand, when it is determined that the crystal resonator 201 has reached the end of its life, the controller 43 outputs a control signal to the film thickness sensor 140 in order to replace the crystal resonator 201 with a new crystal resonator 202 (step 106, 107). As a result, the holder 141 rotates by a predetermined angle in the direction of the arrow in FIG. 8, so that the crystal unit 202 is disposed at a position facing the window 143 instead of the crystal unit 201 and is connected to the electrode unit 144. The Thereafter, rate measurement and film thickness measurement using the crystal resonator 202 are performed.

  The replacement from the crystal unit 201 to the crystal unit 202 is typically performed without interrupting film formation on the substrate W. The measurement data of the crystal unit 201 immediately before the replacement and the measurement data of the crystal unit 202 immediately after the replacement are used in combination for the measurement of the film thickness and the film formation rate during the replacement.

  When film formation of a predetermined thickness on the substrate W is completed (step 108), the shutter 16 is closed as shown in FIG. 1, and the substrate W is remounted on the stage 13. At this time, the measurement unit 17 continues the oscillation operation of the crystal resonator 202 of the film thickness sensor 140, and determines the life of the crystal resonator 202 based on the fluctuation range of the frequency change rate at this time (step 109).

  If the fluctuation range exceeds a predetermined value, it is determined that the crystal unit 202 has a life, and the holder 141 is rotated as described above to switch the crystal unit 202 to the next crystal unit 203 (steps 110 and 107). ). On the other hand, when it is determined that the fluctuation range does not exceed the predetermined value and the crystal resonator 202 has not yet reached the end of its life, film formation using the crystal resonator 202 is subsequently started (step 110, 104).

  Thereafter, the film forming process is performed on the plurality of substrates W by repeating the above-described operation. The film thickness sensor 140 is continuously used until all the crystal resonators 201 to 212 reach the end of their lives. Thereby, the throughput of the film forming apparatus 10 is improved, and productivity can be improved.

  As described above, according to the present embodiment, by measuring the fluctuation range of the change rate of the oscillation frequency of the crystal units 201 to 212 or the standard deviation thereof before or during film formation, the crystal units 201 to 212 are defective. Alternatively, the lifetime (replacement time) can be determined.

  As a result, the life of the crystal unit can be detected quickly, and deterioration of film thickness control due to the life of the crystal unit can be prevented. In addition, since the crystal unit can be automatically replaced, it is possible to stably perform a film forming process in which the crystal unit is likely to deteriorate, such as an organic film.

  In addition, since it is possible to avoid film formation using a defective crystal resonator by determining the quality of the crystal resonators 201 to 212 before film formation, it is possible to ensure stable rate control or film thickness measurement. Can do.

  As mentioned above, although embodiment of this invention was described, this invention is not limited only to the above-mentioned embodiment, Of course, a various change can be added.

  For example, in the second embodiment described above, the life of the crystal resonator is determined both during film formation and during non-film formation, but the life determination of the crystal resonator is performed during film formation and during non-deposition. It may be performed only at any one of the time of filming.

  In the second embodiment described above, twelve crystal resonators are mounted on the film thickness sensor 140, but the number of mounted crystal resonators is not limited to this.

  Further, in the second embodiment described above, in the quality determination of the crystal resonator before film formation, the crystal resonator determined to be defective was replaced with a non-defective product, but instead of this, the crystal determined to be defective was replaced. The vibrator may be mounted as it is, and only the crystal vibrator that is determined to be a non-defective product by the controller 43 may be selected and switched.

  Further, in the above embodiment, the vacuum deposition apparatus has been described as an example of the film forming apparatus. However, the present invention is not limited to this, and the present invention can be applied to other film forming apparatuses such as a sputtering apparatus. In the case of a sputtering apparatus, the vapor deposition source is composed of a sputtering cathode including a target.

DESCRIPTION OF SYMBOLS 10 ... Film-forming apparatus 11 ... Vacuum chamber 12 ... Deposition source 13 ... Stage 14, 140 ... Film thickness sensor 17 ... Measurement unit 18 ... Power supply unit 20, 201-212 ... Crystal oscillator 43 ... Controller 100 ... Film thickness monitor 141 ... Holder 142 ... Casing 143 ... Window part 144 ... Electrode unit

Claims (5)

A method for replacing a crystal resonator in a film thickness sensor for an organic film ,
Oscillate one crystal resonator among the plurality of crystal resonators mounted on the sensor head,
Measure the fluctuation range of the change rate of the oscillation frequency of the one crystal unit,
When the fluctuation range exceeds a predetermined value, the crystal resonator to be oscillated is exchanged from one crystal resonator to another crystal resonator.
How to replace the crystal unit . It is the exchange method of the crystal oscillator according to claim 1,
The fluctuation range is measured at the time of film formation.
How to replace the crystal unit . It is the exchange method of the crystal oscillator according to claim 1,
The fluctuation range is measured when no film is formed.
How to replace the crystal unit . It is the exchange method of the crystal oscillator according to any one of claims 1 to 3,
In the step of measuring the fluctuation range, a standard deviation of the fluctuation range of the change rate of the oscillation frequency in a certain period is measured.
How to replace the crystal unit . A holder that supports the first and second crystal units; a casing that rotatably accommodates the holder; and a window that is formed to face the first crystal unit and allows a vapor deposition material to pass therethrough. A sensor head;
The first crystal unit is oscillated, the fluctuation range of the change rate of the oscillation frequency of the first crystal unit is measured, and when the fluctuation range exceeds a predetermined value , the second crystal unit Rotating the holder to a position facing the window, and oscillating the second crystal resonator ,
A film thickness monitor comprising:

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