WO2016140321A1 - Sensor for film thickness monitoring device, film thickness monitoring device provided with same, and method for manufacturing sensor for film thickness monitoring device - Google Patents

Abstract

[Problem] To provide a sensor for a film thickness monitoring device and a film thickness monitoring device provided with the same, whereby the precision of film thickness measurement can be enhanced by a simple configuration and a highly precise film formation rate can be realized. [Solution] The present invention is provided with: an SC-Cut quartz oscillator having a quartz plate which is θ-rotated about the Z axis and φ-rotated about the X axis in an orthogonal coordinate system of an X axis, a Y axis, and a Z axis which are the quartz crystal axes, and having θ and φ whereby the frequency deviation of the quartz oscillator at a temperature of 10-170°C is ±20 ppm or less; and a sensor head for retaining the quartz oscillator, the sensor head not having a cooling means for cooling the quartz oscillator.

Description

Film thickness monitoring device sensor, film thickness monitoring device including the same, and method for manufacturing film thickness monitoring device sensor

The present invention relates to a sensor for a film thickness monitoring device used for measuring a film thickness of a thin film formed on a crystal resonator, a film thickness monitoring device including the sensor, and a method for manufacturing the sensor for the film thickness monitoring device.

In film formation processes such as vacuum evaporation, sputtering, and CVD (chemical vapor deposition), a film thickness monitoring (film formation control) device is used to control the film thickness on the object to be formed and the evaporation rate (deposition rate). It is done. As this film thickness monitoring device, there is known a device that controls so as to perform stable film formation by measuring the film thickness of a thin film formed on a crystal resonator. Such a film thickness monitoring apparatus measures the film thickness of a substance by utilizing the fact that the resonance vibration (such as sub-vibration, sliding vibration, and bending vibration) changes when the substance adheres to the surface of the crystal unit.

In order to maintain stable oscillation of the crystal unit, for example, Patent Document 1 discloses a technique relating to film thickness monitoring by a crystal unit made of an AT-cut substrate having a temperature drift of a resonance frequency from room temperature to 80 ° C. of 20 ppm or less. It is disclosed. This technique reduces the variation in the film forming rate due to the temperature change of the cooling water by not performing the cooling process of the crystal unit until the temperature of the sensor head exceeds 80 ° C. On the other hand, when this technology exceeds 80 ° C., the temperature drift of the resonance frequency due to the temperature rise is limited by the cooling process.

Further, Patent Document 2 discloses a quartz crystal microbalance sensor device that uses an SC-Cut quartz resonator as a sensor head. This quartz crystal microbalance sensor device reduces the influence on the oscillation frequency caused by exposure to a high temperature in the deposition environment during deposition, which is a problem with the AT-Cut quartz resonator.

JP 2006-78302 A JP 2006-292733 A

In order to perform the water cooling treatment, it is necessary to provide a cooling means for circulating cooling water such as a pump and a pipe. Although this cooling process has the above-described action, there is a possibility that the film forming apparatus or the like may be immersed in water due to water leakage from the cooling means. Moreover, since it is necessary to provide a cooling means, the structure of a vapor deposition apparatus will be complicated.

In addition, when an SC-Cut crystal resonator is used, frequency fluctuation due to temperature in a high temperature environment is suppressed as much as possible as compared with the case of using an AT-Cut crystal resonator as described above, and highly accurate measurement can be performed. it can. However, Patent Document 2 merely discloses the use of an SC-Cut crystal resonator, and does not disclose the detailed configuration of the SC-Cut crystal resonator that can accurately measure in the film forming process. It wasn't. Further, in a film forming apparatus such as a vacuum evaporation apparatus or a sputtering apparatus, a thin film is formed not only on a film forming target but also on a crystal resonator. When this thin film becomes thick, the resonance vibration of the crystal resonator becomes unstable or deviates from the frequency measurement range due to peeling of the evaporative substance film on the crystal resonator or accumulation of internal stress. However, Patent Document 2 does not consider these circumstances in the film forming apparatus.

The present invention has been made in consideration of such circumstances. A sensor for a film thickness monitoring apparatus capable of improving the film thickness measurement accuracy with a simple configuration and realizing a highly accurate film formation rate, and It is an object of the present invention to provide a film thickness monitoring device used and a method for manufacturing a film thickness monitoring device sensor.

A sensor for a film thickness monitoring device according to the present invention has a crystal plate that rotates around the Z axis in the Cartesian coordinate system X-axis, Y-axis, and Z-axis, which is the crystal axis, and rotates around the X axis by φ. An SC-Cut crystal resonator having the above θ and φ with a frequency deviation of ± 20 ppm or less when the temperature of the crystal resonator is 10 to 170 ° C., and a cooling means for holding the crystal resonator and cooling the crystal resonator And a sensor head that does not have.

Further, a film thickness monitoring apparatus according to the present invention includes the above-described sensor for film thickness monitoring apparatus.

Furthermore, the method for manufacturing a sensor for a film thickness monitoring apparatus according to the present invention includes a quartz crystal that is rotated about the Z axis by θ rotation around the X axis and rotated about the X axis in the Cartesian coordinate system X-axis, Y-axis, and Z-axis. In a method for manufacturing a film thickness monitoring device sensor comprising: an SC-Cut crystal resonator having a plate; and a sensor head that holds the crystal resonator, θ and φ are θ ₁ and φ ₁ , and The difference in frequency between the reference temperature and the comparison temperature when the quartz plate has θ ₁ and φ ₁ is defined as ΔF _1, and three sets (θ ₁ , φ ₁ , ΔF ₁ ) are determined, and three sets Obtaining a first expression θ ₁ x + φ ₁ y + ΔF ₁ z = 0 that is an expression of a plane passing through (θ ₁ , φ ₁ , ΔF ₁ ), θ and φ being θ ₂ and φ ₂ , and Tokoro to the surface of the crystal oscillator when the crystal plate having the theta ₂ and phi ₂ 3 pairs of the maximum value of the difference in frequency is defined as [Delta] F ₂ in the While thermal shock temperature is added before and applied _{(θ 2, φ 2, ΔF} 2) determining the three sets of the A step of obtaining a second equation θ ₂ x + φ ₂ y + ΔF ₂ z = 0, which is a plane equation passing through (θ ₂ , φ ₂ , ΔF ₂ ), and z = 0 in the first equation and the second equation To obtain x and y, and a step of incorporating a quartz crystal resonator having a quartz plate with the obtained x and y into θ and φ, respectively, into the sensor head.

In the film thickness monitoring device sensor according to the present invention, the film thickness monitoring device using the same, and the method for manufacturing the film thickness monitoring device sensor, the measurement accuracy of the film thickness is improved with a simple configuration, and the film is formed with high accuracy. Rate can be realized.

The schematic block diagram of the vacuum evaporation system which can apply the sensor for film thickness monitoring apparatuses in this embodiment, and the film thickness monitoring apparatus using the same. The graph which shows the frequency temperature characteristic of the sensor provided with the AT-Cut crystal resonator. The graph which shows the frequency temperature characteristic of the sensor provided with the SC-Cut crystal resonator. The graph which shows the frequency temperature characteristic of an AT-Cut crystal resonator. The graph which compares the frequency temperature characteristic of an AT-Cut crystal resonator with the film thickness (oscillation frequency) of the formed Al thin film. The graph which shows the time change of the frequency at the time of giving a thermal shock so that it may become predetermined temperature on the surface of an AT-Cut crystal oscillator. The graph which compared the time change of the frequency at the time of giving a thermal shock so that it may become predetermined temperature on the surface of an AT-Cut crystal resonator by the film thickness (oscillation frequency) of the formed thin film. The graph which compares the frequency temperature characteristic of the SC-Cut crystal resonator with the film thickness (oscillation frequency) of the formed Al thin film. The graph which compared the time change of the frequency at the time of giving a thermal shock so that it may become predetermined temperature on the surface of a SC-Cut crystal oscillator by the film thickness (oscillation frequency) of the formed thin film. A graph comparing temporal changes in the oscillation frequency of a crystal resonator between a film thickness monitoring device including a sensor using an AT-Cut crystal resonator and a film thickness monitoring device including a sensor using an SC-Cut crystal resonator. . The graph which compared the time change of the vapor deposition rate with the film thickness monitoring apparatus provided with the sensor using an AT-Cut crystal oscillator, and the film thickness monitoring apparatus provided with the sensor using an SC-Cut crystal oscillator. The graph which compared the time change of a power supply output with the film thickness monitoring apparatus provided with the sensor using an AT-Cut crystal oscillator, and the film thickness monitoring apparatus provided with the sensor using an SC-Cut crystal oscillator. The schematic block diagram of the sputtering device to which the film thickness monitoring apparatus in this embodiment is applied.

Embodiments of a sensor for a film thickness monitoring apparatus according to the present invention, a film thickness monitoring apparatus using the same, and a method for manufacturing the film thickness monitoring apparatus sensor will be described with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram of a vacuum deposition apparatus 1 to which a film thickness monitoring apparatus sensor 3 and a film thickness monitoring apparatus 2 using the same according to the present embodiment can be applied.

The film thickness monitoring device sensor 3 (sensor 3) in the present embodiment is applied to a vacuum vapor deposition device 1 as shown in FIG. The vacuum evaporation apparatus 1 is used for film formation for, for example, semiconductors, metal films for electrodes, organic EL films, and the like. The vacuum deposition apparatus 1 is configured such that an evaporation source 11 for evaporating a film forming material, a film forming target 12, and a film forming material are vaporized with respect to the film forming target 12 before the film forming process. And a shutter mechanism 13 for blocking steam. The vacuum deposition apparatus 1 includes a crystal oscillation type film thickness monitoring apparatus 2 as a film thickness monitoring apparatus.

The film thickness monitoring device 2 includes a sensor 3, an oscillator 15, and a film thickness meter 16. The sensor 3 holds the crystal resonator by the sensor head. The crystal resonator includes a crystal plate and an electrode that is provided on the crystal plate and applies a voltage. The crystal unit is an SC-Cut crystal plate that is cut by rotating around the Z axis in the orthogonal coordinate system X-axis, Y-axis, and Z-axis, which is the crystal axis of the crystal plate, and rotating around the X-axis by φ. A crystal resonator using SC (SC-Cut crystal resonator) having a frequency deviation (frequency temperature characteristic) of ± 20 ppm or less when the temperature of the crystal resonator is 10 to 170 ° C. Preferably, the crystal resonator has θ and φ that have a frequency deviation of ± 10 ppm or less when the temperature of the crystal resonator is 20 to 65 ° C. Preferably, in the crystal resonator, a change in frequency when the thermal shock is applied to the surface of the crystal resonator with respect to the frequency before the thermal shock of 50 ° C. or less is applied to the surface of the crystal resonator is ± It has (theta) and (phi) used as 10 ppm or less. The reason why the frequency deviation is set to ± 20 ppm or less is that the range in which the film thickness measurement and the like can be accurately performed is ± 20 ppm or less.

The crystal resonator preferably has a rotation angle θ of 33 ° 40 ′ ± 16 ′ and a rotation angle φ of 24 ° 00 ′ ± 6 °. Particularly preferably, the rotation angle θ is 33 ° 40 ′ and the rotation angle φ is 24 ° 00 ′. Various metal materials such as gold and silver can be applied to the electrodes. The crystal resonator detects the film thickness by vibrating according to the film thickness of the film forming material attached to the surface. The crystal resonator has a resonance frequency of 2 M to 30 MHz, for example.

The oscillator 15 oscillates at the resonance frequency of the crystal resonator, and outputs the measured change in the oscillation frequency of the crystal resonator to the film thickness meter 16 as an electrical signal. The film thickness meter 16 calculates the film thickness of the film formation target 12 and the current vapor deposition rate based on the electrical signal from the oscillator 15, and outputs an appropriate power instruction value to the evaporation source power source 17 to be set. A feedback signal is output so that the deposition rate becomes high. The evaporation source power supply 17 outputs required power to the evaporation source 11 based on the output of the film thickness monitoring device 2.

Hereinafter, details of the sensor 3 will be described. The sensor 3 in the present embodiment realizes high-precision measurement without having a cooling means for cooling the crystal unit, which is usually included in a sensor having a crystal unit using an AT-Cut crystal plate. be able to.

That is, a sensor including a crystal resonator (AT-Cut crystal resonator) using an AT-Cut crystal plate has a large frequency variation due to temperature in a high temperature environment. As a result, when the temperature of the quartz plate rises due to heat from the evaporation source or adhesion of high-temperature deposits, a large measurement error occurs in the film thickness meter.

First, the superiority of the sensor 3 having a frequency deviation of ± 20 ppm or less at a crystal resonator temperature of 10 to 170 ° C. will be described in comparison with a sensor having an AT-Cut crystal resonator.

FIG. 2 is a graph showing a frequency temperature characteristic of a sensor having an AT-Cut crystal resonator of about 20 to 170 ° C. The AT-Cut crystal resonator in FIG. 2 is cut so that the rotation angle θ around the Z-axis of the orthogonal coordinate system X-axis, Y-axis, and Z-axis of the crystal crystal axis is 35 ° 15 ′. . Further, the crystal resonator has a resonance frequency of 5 MHz.

The AT-Cut crystal resonator has good frequency temperature characteristics from about 20 ° C. to 80 ° C., but the frequency deviation rapidly increases from around 100 ° C. For this reason, it is necessary to supply cooling water to the sensor head to cool the crystal unit so that the crystal unit falls within a temperature range having a good frequency deviation. That is, when an AT-Cut crystal resonator is used, a cooling means is essential to improve measurement accuracy even in a high temperature region.

Here, FIG. 3 is a graph showing frequency-temperature characteristics of a sensor equipped with an SC-Cut crystal resonator. For easy comparison, FIG. 3 also shows the frequency temperature characteristics of the sensor including the AT-Cut crystal resonator shown in FIG. The SC-Cut crystal resonator in FIG. 3 is an example of an SC-Cut crystal resonator having θ and φ that have a frequency deviation of ± 20 ppm or less when the temperature of the crystal resonator is 10 to 170 ° C. Specifically, this crystal resonator has a rotation angle θ around the Z-axis of the orthogonal coordinate system X-axis, Y-axis, and Z-axis of the crystal crystal axis of 33 ° 40 ′ and a rotation angle φ around the X-axis of 24 °. It is cut so that it becomes 00 '. Further, the crystal resonator has a resonance frequency of 5 MHz.

The sensor 3 in the present embodiment has a frequency deviation of ± 5 ppm or less particularly in a high temperature range of about 30 ° C. to 170 ° C. That is, it can be said that the sensor 3 is less likely to cause a measurement error due to temperature even in a high temperature region and can be measured with high accuracy as in the above-described AT-Cut crystal resonator.

For this reason, the sensor 3 in the present embodiment does not need to be provided with a water cooling means for cooling the sensor 3, and simplification of the configuration can be realized. Since the cooling means can be omitted, the sensor 3 is also effective in that it can avoid a failure of the vapor deposition apparatus due to water leakage from the water cooling means. As a result, the frequency fluctuation due to temperature is suppressed, and the film thickness measurement and the evaporation rate control can be performed with high accuracy as the entire apparatus.

Next, the superiority of the sensor 3 when the frequency deviation at a crystal resonator temperature of 20 to 65 ° C. is ± 10 ppm or less will be described in comparison with a sensor having an AT-Cut crystal resonator.

FIG. 4 is a graph showing frequency temperature characteristics of 20 to 65 ° C. of a sensor equipped with an AT-Cut crystal resonator. The AT-Cut crystal resonator used for comparison in FIG. 4 and the following description has a rotation angle θ around the Z-axis of the orthogonal coordinate system X-axis, Y-axis, and Z-axis of the crystal crystal axis of 35 ° 15 ′. It was cut to become.

The AT-Cut crystal resonator has good frequency temperature characteristics at about 20 ° C. to 70 ° C. with an inflection point of about 25 ° C. However, if a thin film is formed on the quartz resonator by being repeatedly used in the film forming process, the frequency temperature characteristic changes.

Here, FIG. 5 is a graph comparing the frequency temperature characteristics of the AT-Cut crystal resonator with the film thickness (oscillation frequency) of the formed Al thin film. FIG. 5 shows frequency temperature characteristics when the thin film is not formed (new) and when the oscillation frequency changes stepwise as a result of forming the thin film. Further, in FIG. 5, each line is represented for each output frequency (5.00 MHz (new, no thin film), 4.903 MHz, 4.804 MHz, 4.694 MHz) of the oscillator which decreases depending on the film thickness, and is a graph. The Y axis of shows the temperature drift frequency (Hz). Note that the phenomenon in which the frequency temperature characteristics of the crystal resonator greatly change when the deposited film is formed in this way is a fact discovered by repeated experiments by the present inventors.

When an Al thin film is deposited on the crystal unit, the oscillation frequency of the crystal unit changes. In other words, the frequency temperature characteristic has a downward slope according to the amount of thin film formed. Conventionally, there has been disclosed an example in which the accuracy of a measurement result is improved by correcting the frequency temperature characteristic according to the temperature of a sensor (sensor head) using an AT-Cut crystal resonator. However, when the thin film adheres to the crystal resonator and the frequency temperature characteristic becomes large as described above, even if correction is performed according to the temperature, the frequency is out of the correction range, and appropriate measurement cannot be performed. For this reason, the conventional film thickness monitoring apparatus cannot perform sufficient measurement.

FIG. 6 is a graph showing a change with time in frequency when a thermal shock is applied to the surface of the AT-Cut crystal resonator so as to reach a predetermined temperature. The Y axis of the graph represents the temperature drift frequency (Hz) (the same applies to FIGS. 7 to 9). The thermal shock applied to the AT-Cut crystal resonator was radiant heat from a 30 W halogen lamp (the same applies to FIGS. 7 and 9). In the electron beam evaporation system, when an AT-Cut quartz crystal (θ = 35 ° 15 ') is used, the frequency change due to radiant heat when the shutter is opened is about 200 Hz at maximum, and the surface temperature of the quartz crystal is about 50 ° C. It was found experimentally. For this reason, a change corresponding to 200 Hz, that is, a situation corresponding to a surface temperature of 50 ° C. was made using a halogen lamp with an output of 30 W.

When a sensor using an AT-Cut crystal resonator is combined with an oscillator, a thermal shock is suddenly applied to the sensor by the radiant heat of the evaporation source when the shutter is opened by the shutter mechanism. As a result, the output frequency from the oscillator rapidly increases without following the frequency temperature characteristics. The occurrence of “thermal shock” is due to the internal stress of the crystal unit due to the difference in thermal expansion coefficient between the crystal unit made of silicon dioxide and the metal material for electrodes such as gold and silver. I understood.

FIG. 7 is a graph comparing the time change of the frequency when the thermal shock is applied to the surface of the AT-Cut crystal resonator so as to reach a predetermined temperature by the film thickness (oscillation frequency) of the formed thin film. In FIG. 7, each line represents an oscillator output frequency that decreases depending on the film thickness (5.00 MHz (new, no thin film), 4.970 MHz, 4.900 MHz, 4.845 MHz, 4.804 MHz, 4.743 MHz. 4.695 MHz).

When a thin film is formed on the quartz resonator, it can be seen that the frequency variation varies according to the oscillation frequency of the AT-Cut quartz resonator as shown in FIG. As a result, correction is difficult as in the case of the frequency temperature characteristic, and the controllability of the deposition rate, which is the film formation speed, and the accuracy of film thickness measurement are reduced. For this reason, as in the case of frequency temperature characteristics, even when correction is performed in a state where no thin film is formed, variation occurs as the thin film is formed, and accurate measurement and control cannot be performed.

In contrast, a sensor using an SC-Cut crystal resonator has a stable film thickness without being affected by frequency temperature characteristics and frequency changes due to thermal shock even when a thin film is formed on the surface. Measurement and deposition rate can be controlled.

FIG. 8 is a graph comparing the frequency temperature characteristics of the SC-Cut crystal resonator with the film thickness (oscillation frequency) of the formed Al thin film. In FIG. 8, each line is represented for each output frequency (5.00 MHz (new, no thin film), 4.90 MHz, 4.80 MHz, 4.70 MHz) of the oscillator that decreases depending on the film thickness.

FIG. 9 is a graph comparing the time change of the frequency when the thermal shock is applied to the surface of the SC-Cut crystal resonator so as to reach a predetermined temperature by the film thickness (oscillation frequency) of the formed thin film. In FIG. 9, each line is represented for each output frequency of the oscillator (5.00 MHz (new, no thin film), 4.97 MHz, 4.90 MHz, 4.80 MHz, 4.70 MHz) that decreases depending on the film thickness. The

The SC-Cut crystal resonator used for the description has a rotation angle θ around the Z axis of the crystal axis X, Y, and Z of 34 °, and a rotation angle φ around the X axis of 22 ° 30 ′. It was cut to become.

For the SC-Cut crystal resonator, as shown in FIG. 8, when the thin film is not formed (5.00 MHz) and the thin film is formed most (4.70 MHz), the frequency is maximum. It changes only about 40Hz. This is about 1/10 of the change in frequency of the AT-Cut crystal resonator. This also indicates that the frequency temperature characteristics of the crystal resonator do not change even when the film thickness is increased, that is, even when the film forming process is repeated a plurality of times.

Similarly, the time change of the frequency with respect to the thermal shock shown in FIG. 9 similarly changes only about 40 Hz at the maximum, and the change is small compared with the AT-Cut crystal resonator. In other words, the SC-Cut quartz resonator has little change in both frequency temperature characteristics and frequency change due to thermal shock regardless of the film thickness, and maintains measurement with small error even when the film formation process is repeated multiple times. can do. As a result, the film thickness monitoring apparatus using the SC-Cut crystal resonator as a sensor can control the deposition rate appropriately.

Next, a method for determining the cut angle of the SC-Cut crystal resonator, that is, a method for manufacturing a sensor for a film thickness monitoring device will be described.

As described above, in the SC-Cut crystal resonator, the change in the frequency temperature characteristics according to the film thickness and the change in the frequency with respect to the thermal shock do not change according to the film thickness as compared with the AT-Cut crystal resonator. Therefore, in order to minimize frequency change due to frequency temperature characteristics and thermal shock when the film thickness is gradually increased by repeating the film formation process and forming a thin film on the crystal unit, the thin film It is only necessary to minimize frequency change due to the frequency-temperature characteristics and thermal shock when no is formed.

In the present embodiment, the frequency temperature characteristic when a thin film is not formed and the θ and φ of the SC-Cut crystal resonator capable of minimizing the frequency change due to thermal shock are obtained. The configuration of the SC-Cut crystal resonator suitable for the sensor was determined.

Specifically, an SC-Cut crystal resonator having θ and φ that has a frequency temperature characteristic of ± 10 ppm or less at a crystal resonator temperature of 20 to 65 ° C. (Condition 1). Or, when the thermal shock is applied to the surface of the crystal unit (after being applied) with respect to the frequency before the thermal shock of 50 ° C. or less is applied to the surface of the crystal unit, the change in frequency is ± 10 ppm or less. An SC-Cut crystal resonator having θ and φ (Condition 2). It is assumed that the crystal resonator rotates θ around the Z axis and rotates φ around the X axis in the orthogonal coordinate system X-axis, Y-axis, and Z-axis that are crystal crystal axes. The crystal resonator may satisfy either one of the above conditions 1 and 2, or may satisfy both.

Specifically, the rotation angle θ around the Z axis and the rotation angle φ around the X axis are defined as θ ₁ and φ ₁ , respectively. Also relates to a frequency-temperature characteristic, the difference in frequency between the reference temperature and compared temperature when crystal oscillator having a theta ₁ and phi ₁ is defined as [Delta] F _1. Next, three sets of (θ ₁ , φ ₁ , ΔF ₁ ) are determined. Further, a first equation θ ₁ x + φ ₁ y + ΔF ₁ z = 0, which is a plane equation passing through three sets of (θ ₁ , φ ₁ , ΔF ₁ ), is obtained.

Also, θ and φ are defined as θ ₂ and φ ₂ . And, the maximum value of the difference of frequency in a while on the surface of the crystal oscillator having a theta ₂ and phi ₂ thermal shock at a predetermined temperature is added to the previous applied is defined as [Delta] F _2. Next, three sets of (θ ₂ , φ ₂ , ΔF ₂ ) are determined. Further, a second equation θ ₂ x + φ ₂ y + ΔF ₂ z = 0, which is a plane equation passing through three sets of (θ ₂ , φ ₂ , ΔF ₂ ), is obtained.

Next, in the first expression and the second expression, x and y are obtained by setting z = 0 simultaneously. That is, θ and φ when the frequency changes ΔF ₁ and ΔF ₂ due to frequency temperature characteristics and thermal shock are 0 are obtained. Then, a sensor for a film thickness monitoring device is manufactured by incorporating an SC-Cut crystal resonator having a rotation angle θ around the Z axis and a rotation angle φ around the X axis based on the obtained x and y into the sensor. .

Furthermore, the range of θ and φ in which the change in frequency due to frequency temperature characteristics and thermal shock is ± 10 ppm or less is also obtained based on the first and second formulas. This makes it possible to obtain θ and φ that are suitable for frequency temperature characteristics and frequency change due to thermal shock, and to reduce the frequency fluctuation due to temperature in a high-temperature environment and to have a crystal resonator with excellent measurement accuracy. Sensors can be manufactured.

Hereinafter, a specific example will be described. The oscillation frequency of the SC-Cut crystal resonator is 5 MHz.

In order to obtain the first equation θ ₁ x + φ ₁ y + ΔF ₁ z = 0, three sets of (θ ₁ , φ ₁ , ΔF ₁ ) were obtained as follows. For θ ₁ and φ ₁ , numerical values were arbitrarily selected with reference to θ = 34 ° and φ = 22 ° 30 ′ as a reference. ΔF ₁ was obtained by measurement using an SC-Cut crystal resonator having θ ₁ and φ ₁ . ΔF ₁ was a frequency change at a comparative temperature of 65 ° C. with respect to a reference temperature of 20 ° C. (frequency change at 20 to 65 ° C.).

(Θ ₁ , φ ₁ , ΔF ₁ ) = (33 ° 50 ′, 24 ° 45 ′, −70),
(33 ° 50 ', 25 ° 25', -82),
(34 ° 00 ', 25 ° 25', -147)
The formula of the plane passing through the three points was as follows.

[Equation 1]
−40.687x−2.004y−0.111389z + 1418.37 = 0 (1)

Further, in order to obtain the second equation θ ₂ x + φ ₂ y + ΔF ₂ z = 0, three sets (θ ₂ , φ ₂ , ΔF ₂ ) were obtained as follows. θ ₂ and φ ₂ were set to the same values as θ ₁ and φ ₁ . ΔF ₂ was obtained by measurement using an SC-Cut crystal resonator composed of θ ₂ and φ ₂ . The radiant heat of a 30 W halogen lamp was used as a thermal shock, and the surface temperature of the crystal unit was set to 50 ° C. That is, ΔF ₂ is a frequency change when a thermal shock is applied to the surface of the crystal resonator with respect to a frequency before a thermal shock of 50 ° C. or less is applied to the surface of the crystal resonator.

(Θ ₂ , φ ₂ , ΔF ₂ ) = (33 ° 50 ′, 24 ° 45 ′, −33),
(33 ° 50 ', 25 ° 25', -51),
(34 ° 00 ', 25 ° 25', -63)
The formula of the plane passing through the three points was as follows.

[Equation 2]
−8.004x−3.006y−0.111389z + 341.52 = 0 (2)

Next, x and y when z = 0 are obtained. That is, θ and φ when the frequency changes ΔF ₁ and ΔF ₂ are 0 are obtained. As a result, (θ, φ) = (33 ° 41 ′, 23 ° 57 ′) was obtained.

Next, the range of θ and φ in which the frequency temperature characteristic is ± 10 ppm and the frequency change due to thermal shock is ± 10 ppm is obtained. In the case of a 5 MHz crystal resonator, ΔF ₁ and ΔF ₂ may be ± 50 Hz in order to set these to ± 10 ppm. Therefore, θ and φ when ΔF ₁ and ΔF ₂ are the following combinations are obtained from the above equations (1) and (2). The results are as follows.

When (ΔF ₁ , ΔF ₂ ) = (50, 50), (θ, φ) = (33 ° 38 ′, 24 ° 57 ′)
When (ΔF ₁ , ΔF ₂ ) = (50, −50), (θ, φ) = (33 ° 25 ′, 29 ° 17 ′)
When (ΔF ₁ , ΔF ₂ ) = (− 50, 50), (θ, φ) = (33 ° 56 ′, 18 ° 36 ′)
When (ΔF ₁ , ΔF ₂ ) = (− 50, −50), (θ, φ) = (33 ° 44 ′, 22 ° 52 ′)

As a result, the range of θ and φ in which the frequency change is ± 10 ppm or less is (θ, φ) = (33 ° 40 ′ ± 16 ′, 24 ° 00 ′ ± 6 °)
It becomes. When (θ, φ) = (33 ° 40 ′, 24 ° 00 ′), the temperature drift frequency of the SC-Cut crystal resonator can be minimized.

As described above, the film thickness monitoring device sensor according to the present embodiment, the film thickness monitoring device including the sensor, and the film thickness monitoring device sensor manufactured by the method for manufacturing the film thickness monitoring device sensor are formed with a thin film. However, by utilizing the characteristics of the SC-Cut crystal resonator that the frequency-temperature characteristics change and the frequency change due to thermal shock are small, the film thickness measurement and evaporation rate are highly accurate, suppressing frequency fluctuations due to temperature in a high-temperature environment. Control becomes possible.

In addition, in the method for manufacturing the sensor for film thickness monitoring device in the present embodiment, in the SC-Cut crystal resonator in which no thin film is formed, θ and φ excellent in frequency temperature characteristics and frequency change due to thermal shock are approximated. Asked. Thereby, even when a thin film is formed, highly accurate film thickness measurement and evaporation rate control can be realized as in the case where a thin film is not formed.

Further, as shown in FIGS. 10 to 12 below, a film thickness monitoring apparatus including a sensor using an SC-Cut crystal resonator is used as a film thickness monitoring apparatus including a sensor head using an AT-Cut crystal resonator. Control is possible with higher accuracy.

FIG. 10 shows a temporal change in the oscillation frequency of a crystal resonator using a film thickness monitoring device including a sensor using an AT-Cut crystal resonator and a film thickness monitoring device including a sensor using an SC-Cut crystal resonator. It is the graph which compared.

FIG. 11 is a graph comparing the time variation of the deposition rate between a film thickness monitoring device including a sensor using an AT-Cut crystal resonator and a film thickness monitoring device including a sensor using an SC-Cut crystal resonator. It is.

FIG. 12 is a graph comparing power output changes over time in a film thickness monitoring device including a sensor using an AT-Cut crystal resonator and a film thickness monitoring device including a sensor using an SC-Cut crystal resonator. It is.

FIG. 10 to FIG. 12 are examples in which the closed shutter is opened when 250 seconds elapses and low-rate film formation is performed. In the case of a sensor using an AT-Cut crystal resonator, a temperature drift due to radiant heat occurs in the crystal resonator even when the shutter is in a closed state due to a gradual increase in the output of the power supply. Furthermore, when the shutter is in the open state, the oscillation frequency of the crystal unit is shifted to the higher side due to thermal shock. On the other hand, in the case of a sensor using an SC-Cut crystal resonator, it is understood that there is almost no influence of temperature drift and thermal shock even under the same conditions.

As described above, the film thickness monitoring apparatus including the sensor using the SC-Cut crystal resonator includes the film thickness monitoring apparatus including the sensor using the AT-Cut crystal resonator in the frequency change, the deposition rate change, and the power supply output change. The film thickness can be monitored and the film forming process can be controlled without being affected by the temperature in a higher temperature environment.

In addition, although the film thickness monitoring apparatus sensor 3 and the film thickness monitoring apparatus 2 provided with the same in the present embodiment have been described by taking the vacuum vapor deposition apparatus 1 as an example, they may be applied to a sputtering apparatus or a CVD apparatus.

FIG. 13 is a schematic configuration diagram of a sputtering apparatus to which the film thickness monitoring apparatus according to this embodiment is applied.

The sputtering apparatus 21 arranges a substrate 32 and a target electrode 33 formed in accordance with the composition of the film forming material in a vacuum chamber 31 so as to face each other. In the vacuum chamber 31, a plasma atmosphere 35 is formed by applying predetermined power from a high-frequency power source 34 to cause glow discharge. The sputtering apparatus 21 accelerates and collides ions of a rare gas ionized in the plasma atmosphere 35 toward the target, and sputters particles (target atoms) generated thereby are deposited and deposited on the substrate surface. Thereby, the sputtering apparatus 21 forms a thin film.

Such a sputtering apparatus 21 includes a film thickness monitoring apparatus 22 including a sensor 36, an oscillator 37, and a film thickness meter 38, as in the vacuum vapor deposition apparatus 1 shown in FIG. An impedance matching unit 39 for matching impedance between the high frequency power supply 34 and the target electrode 33 is also provided.

Such a sputter device 21 and a CVD device are exposed to plasma and thus have a high temperature and require water cooling. However, the sensor provided with the SC-Cut crystal resonator according to the present invention is characterized in that the frequency deviation due to temperature in the high temperature region is smaller than that of the AT-Cut crystal resonator. In addition, this sensor generates less temperature drift than a sensor using an AT-Cut crystal resonator. Therefore, the sensor according to the present invention can be suitably used as the sensor 36 in the sputtering apparatus 21 and the CVD apparatus.

It should be noted that the SC-Cut crystal resonator can be reused after being used in the film forming process, after the formed thin film and electrode are peeled off and the electrode is formed again.

DESCRIPTION OF SYMBOLS 1 Vacuum evaporation apparatus 3, 36 Sensor for film thickness monitoring apparatus 2, 22 Film thickness monitoring apparatus 10, 31 Vacuum tank 11 Evaporation source 15, 37 Oscillator 16, 38 Film thickness meter 17 Evaporation source power source 21 Sputter apparatus 32 Substrate 33 Target Electrode 34 High frequency power supply 35 Plasma atmosphere 39 Impedance matching device

Claims (8)

A crystal plate that has a crystal plate that is rotated by θ around the Z axis in the Cartesian coordinate system X-axis, Y-axis, and Z-axis and rotated by φ around the X-axis, and the temperature of the crystal unit is 10 to 170 ° C. An SC-Cut crystal resonator having the θ and φ with a deviation of ± 20 ppm or less;
A sensor for a film thickness monitoring device, comprising: a sensor head that holds the crystal resonator and does not have a cooling unit that cools the crystal resonator. 2. The film thickness monitoring device sensor according to claim 1, wherein the crystal resonator has the θ and φ at which the frequency deviation when the temperature of the crystal resonator is 20 to 65 ° C. is ± 10 ppm or less. The crystal resonator has a frequency change of ± 10 ppm when the thermal shock is applied to the surface of the crystal resonator with respect to the frequency before the thermal shock of 50 ° C. or less is applied to the surface of the crystal resonator. The film thickness monitoring device sensor according to claim 2, which has the following θ and φ. The film thickness monitoring device sensor according to any one of claims 1 to 3, wherein the θ is 33 ° 40 '± 16' and the φ is 24 ° 00 '± 6 °. The sensor for film thickness monitoring device according to claim 4, wherein the θ is 33 ° 40 'and the φ is 24 ° 00'. A film thickness monitoring device comprising the film thickness monitoring device sensor according to any one of claims 1 to 5. An SC-Cut crystal unit having a crystal plate rotated by θ around the Z axis in the Cartesian coordinate system X-axis, Y-axis, and Z-axis and φ-rotated around the X axis, and holding the crystal unit In a manufacturing method of a sensor for a film thickness monitoring device comprising:
When θ and φ are θ ₁ and φ ₁ and the crystal plate has θ ₁ and φ ₁ , the frequency difference between the reference temperature and the comparison temperature is defined as ΔF _1, and three sets of ( theta _1, phi _1, [Delta] F ₁₎ to determine the three sets of the (theta _1, phi _1, and obtaining a first expression _{θ 1 x + φ 1 y +} ΔF 1 z = 0 is the equation of a plane passing through the [Delta] F ₁₎ ,
When θ and φ are θ ₂ and φ ₂ and the quartz plate has θ ₂ and φ ₂ and before the thermal shock of a predetermined temperature is applied to the surface of the crystal resonator, 3 pairs of the maximum value of the difference in frequency is defined as [Delta] F ₂ in the _{(θ 2, φ 2, ΔF} 2) determining the three sets of the _{(θ 2, φ 2, ΔF} 2) of a plane passing through the Obtaining a second equation θ ₂ x + φ ₂ y + ΔF ₂ z = 0, which is an equation;
Obtaining x and y by simultaneously setting z = 0 in the first formula and the second formula;
A process for manufacturing a sensor for a film thickness monitoring apparatus, comprising: incorporating a crystal resonator having a crystal plate in which the obtained x and y are respectively θ and φ into the sensor head. Obtaining the range of θ and φ based on the first and second formulas such that the frequency change due to frequency temperature characteristics and thermal shock is ± 10 ppm or less;
The manufacturing of the film thickness monitoring device sensor according to claim 7, further comprising a step of incorporating a crystal resonator having a crystal plate having the θ and φ within the range of the obtained θ and φ into the sensor head. Method.

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