JP2003121116A - Vacuum ultraviolet optical film thickness monitor and vacuum film forming apparatus provided therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide both a highly sensitive vacuum ultraviolet optical film thickness monitor capable of being used even in a vacuum film forming apparatus in an high-temperature environment of 200 deg.C or higher and a vacuum film forming apparatus provided therewith. SOLUTION: The vacuum ultraviolet optical film thickness monitor is an optical system with a minimum number of constituting mirrors and lenses, receives signal light at a light receiving part arranged in proximity of a sample to be measured, converts the received signal light of wavelengths from the ultraviolet to vacuum ultraviolet ranges into light in the visible range by a wavelength converting part constituted by applying a salicylic acid, and detects the visible light after the conversion by a sensor. By this, it is possible to obtain the vacuum ultraviolet optical film thickness monitor capable of highly sensitively detecting the signal light of wavelengths in the vacuum ultraviolet range. By incorporating such an optical film thickness monitor in the vacuum film forming apparatus, it is possible to obtain the vacuum film forming apparatus capable of forming a film while monitoring the film thickness of an optical film formed in a high-temperature environment of 200 deg.C or higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum ultraviolet optical film thickness monitor and a vacuum film forming apparatus provided with the same, and more particularly, it can be used even in a vacuum film forming apparatus having a high temperature environment of 200 ° C. or higher. The present invention relates to a vacuum ultraviolet optical film thickness monitor and a vacuum film forming apparatus including the same.

[0002]

2. Description of the Related Art A conventional optical film thickness monitor and a spectroscopic system equipped with the same include a light source condensed by a lens, reflected by an optical element such as a mirror, and made incident on a sample to be measured. Generally, the reflected light or transmitted light from the sample is reflected by an optical element such as a mirror and guided to a spectroscope such as a monochromator.

FIG. 10 is a diagram for explaining the configuration of a conventional general spectroscopic system, which includes a light source 11 and a condenser lens 1.
2, an optical system composed of mirrors 13a to 13d for reflecting light, a monochromator 15, a photodetector 16, and A
The D / D converter 17 and the PC 18 for data processing are used to collect the light emitted from the light source 11 into the condenser lens 12.
The light is condensed by, and reflected by the mirrors 13a and 13b to be incident on the measurement sample 14. The reflected light from the measurement sample 14 is reflected by the mirrors 13c and 13d and guided to the monochromator 15, where it is amplified by the photodetector 16 such as a photomultiplier tube and A / D by the A / D converter 17. After the conversion, the data is transmitted to the PC 18 for spectrum analysis processing and the like.

[0004]

The energy of light called a vacuum ultraviolet ray (or extreme ultraviolet ray) in the wavelength range of 200 nm to soft X-rays (tens of nm) is the energy that causes the strongest interaction with a substance. Therefore, the spectral analysis in the vacuum ultraviolet region is extremely important for the study of physical properties of gases and solids, especially for the study of excited states of atoms and molecules.

With the recent miniaturization of semiconductor device design, a next-generation stepper using a fluorine laser as a light source for submicron level microfabrication has been developed. It is used in the optical system of this stepper. In order to produce a high-precision lens in the vacuum ultraviolet region, it is necessary to deposit a metal such as aluminum (Al) in a predetermined film thickness on a lens such as magnesium fluoride (MgF ₂ ), which is a highly accurate film. In order to control the thickness, it is required to accurately monitor the change in the intensity of the vacuum ultraviolet rays reflected (or transmitted) from the metal film being formed in the vacuum film forming apparatus that can reach a high temperature of 200 ° C. or higher.

However, in the conventional optical film thickness monitor and the spectroscopic system constructed using the same, a sufficient signal light intensity can be obtained for light of wavelengths from the infrared / visible region to the ultraviolet region. , When attempting to detect light in the ultraviolet to vacuum ultraviolet region, which is a shorter wavelength region, the signal light intensity must be extremely low due to the special property of light in this wavelength region. However, there is a problem that these configurations are complicated and very expensive. The reason is as follows.

First, since vacuum ultraviolet light is strongly absorbed by air, it is necessary to store all of the light source, the spectroscope, the detector, etc. that compose the optical film thickness monitor in a vacuum container.

Secondly, since vacuum ultraviolet light is strongly absorbed by glass and quartz, which are often used as optical parts, its intensity is easily attenuated while a weak optical signal from a measurement sample is guided to a detection system. It is difficult to obtain sufficient intensity (light intensity) for spectrum analysis, and as a result, S
/ N becomes extremely low.

Thirdly, since there is no substance that passes all wavelength regions in the vacuum ultraviolet region, it is difficult to use a prism to disperse the spectrum, and it is impossible to use an absorption tube or a discharge tube having a window plate. thing.

Fourth, the vacuum ultraviolet light has a very low reflectance with respect to any kind of metal surface.

Fifth, there is no suitable light source, and a stable continuous spectrum cannot be easily obtained.

Sixth, if an optical system is designed to solve these difficulties, the device becomes very large and expensive.

In addition to these technical difficulties, when an optical film thickness monitor using light in the vacuum ultraviolet region as a signal light is attached to a vacuum film forming apparatus for in-situ optical film thickness monitoring, the temperature is 200 ° C. Even in the above high temperature environment,
It is necessary to perform stable and highly sensitive monitoring.

The present invention has been made in view of the above problems, and its object is to provide a signal light having a wavelength in the ultraviolet to vacuum ultraviolet range even under a high temperature environment of 200 ° C. or higher. It is an object of the present invention to provide a vacuum ultraviolet optical film thickness monitor capable of detecting with high sensitivity and a vacuum film forming apparatus including the same.

[0015]

In order to achieve such an object, the present invention provides a vacuum ultraviolet optical film thickness monitor according to the invention as claimed in claim 1, wherein the light in the ultraviolet to vacuum ultraviolet range is detected. A light source for emitting light, a spectroscopic means for irradiating the measurement sample with the light emitted from the light source, and a visible light conversion means for converting signal light in the ultraviolet to vacuum ultraviolet region from the measurement sample into visible light It is characterized by comprising a light receiving means and a signal light detecting means for receiving the visible light converted by the light receiving means and detecting a signal.

The invention described in claim 2 is the same as claim 1
In the vacuum ultraviolet optical film thickness monitor according to, the visible light converting means, a salicylic acid-coated quartz plate, or
It is characterized by being a magnesium fluoride plate coated with salicylic acid.

The invention described in claim 3 is the same as claim 1.
Alternatively, in the vacuum ultraviolet optical film thickness monitor described in 2,
A chopper provided in the optical path between the light source and the spectroscopic means, a semi-transparent mirror provided in the optical path between the spectroscopic means and the measurement sample, and the reflected light from the semi-transparent mirror is received. And a signal processing means for calculating a difference between the signal light detected by the signal light detecting means and the reference light detected by the reference light receiving means.

The invention according to claim 4 is a vacuum ultraviolet optical film thickness monitoring system, wherein measurement is performed based on the vacuum ultraviolet optical film thickness monitor according to claim 1 and the intensity change of signal light. A film thickness calculating means for calculating the optical film thickness of the sample is provided, and the optical film thickness of the measurement sample is calculated based on a signal output from the VUV optical film thickness monitor.

Furthermore, the invention according to claim 5 is a vacuum film forming apparatus comprising a vacuum film forming means and the vacuum ultraviolet optical film thickness monitoring system according to claim 4, wherein a measurement sample is vacuum-formed. It is characterized in that it is arranged at the film forming sample position of the film means and film formation is carried out while monitoring the optical film thickness of the measurement sample.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1] FIG. 1 is a diagram for explaining the configuration of a spectroscopic system including a vacuum ultraviolet optical film thickness monitor of the present invention. The vacuum ultraviolet optical film thickness monitor 100 is housed in a vacuum container 101. The light source 102 that emits light having a wavelength in the ultraviolet to vacuum ultraviolet region, the condenser lens 103, the diffraction grating 105 provided in the monochromator 104, and the light source 1
02, the two mirrors 106 and 107 arranged to irradiate the measurement sample 108 with the light, and the measurement sample 108.
A light receiving section 109 for receiving reflected light from the ultraviolet to vacuum-ultraviolet light into visible light; an optical fiber 110 for guiding the visible light converted by the light receiving section 109 to the outside of the vacuum container 101; A sensor 111 for recognizing the intensity of the signal light guided by the fiber 110, and a light source power source 112.
And a vacuum pump 113 for creating a high vacuum inside the vacuum container 101.

The ultraviolet-vacuum ultraviolet light emitted from the light source 102 is condensed by the condenser lens 103, and the monochromator 1
Only a desired monochromatic light is selected by the diffraction grating 105 provided in 04, and the monochromatic light is reflected by the mirror 106 and the concave mirror 107, and the measurement sample 1
08 is incident on the measurement surface.

The vacuum ultraviolet optical film thickness monitoring system has an amplifier 114 for amplifying the output signal of the sensor 111 of the vacuum ultraviolet optical film thickness monitor 100.
And A / for converting analog signals to digital signals
A spectroscopic system is configured by the D converter 115 and the PC 116 for processing a digital signal and executing a spectrum analysis process.

FIG. 2 is a diagram for explaining the light intensity distribution of the deuterium lamp used as the light source of the vacuum ultraviolet optical film thickness monitor of the present invention, which has a maximum light intensity near 220 nm and a wavelength range. It is possible to emit ultraviolet to vacuum ultraviolet light having a wavelength of 130 to 300 nm.

The reflected light from the measurement sample 108 is measured by the measurement sample 10 in order to avoid the attenuation of the intensity by the lens or the mirror.
The light is received by the light receiving portion 109 arranged in the vicinity of 8, and guided to the outside of the vacuum container 101 by the optical fiber 110. The material of the optical fiber 110 is quartz glass,
The vacuum ultraviolet light guided in the optical fiber 110 is absorbed by the silica glass.

FIG. 3 is a diagram for explaining an optical loss characteristic when vacuum ultraviolet light is transmitted through an optical fiber.
In the wavelength region shorter than 0 nm, the optical loss increases rapidly,
When it is desired to detect vacuum ultraviolet light having a wavelength of 160 nm or less as signal light, optical loss due to an optical fiber becomes a problem. In order to solve this problem, in the vacuum ultraviolet optical film thickness monitor of the present invention, the vacuum ultraviolet light is converted into visible light by the light receiving portion attached to the tip end of the optical fiber, and the converted visible light is converted by the optical fiber. The signal light is guided to the outside of the vacuum container and the light intensity is recognized by a sensor to detect the signal light.

FIG. 4 is a diagram for explaining an example of the structure of the light receiving portion provided in the VUV optical film thickness monitor of the present invention.
FIG. 4A shows a light receiving unit configured to prevent the temperature of the light receiving unit from rising due to radiant heat from an electron gun, an ion source, a heater, or the like radiated from the measurement environment. (B) suppresses such temperature rise,
In addition, the light receiving section is configured to efficiently guide the signal light from the measurement sample to the optical fiber.

The light receiving portion shown in FIG.
The holding member 410 includes a wavelength conversion unit 411 housed in the optical fiber 10 and a light guide 412 to the optical fiber.
A cooling water circulation path 413 is provided inside the.

The wavelength conversion section 411 has a magnesium fluoride (MgF ₂ ) plate 414, a coating layer 415 of salicylic acid coated on one side thereof, and a visible layer formed by vapor deposition or the like on the opposite side of the MgF ₂ plate. And a thin film 416 that cuts off light having a longer wavelength than light.

Since the melting point of salicylic acid is about 200 ° C. and the inside of the vacuum film forming apparatus during thin film formation can be 200 to 300 ° C., when the vacuum ultraviolet optical film thickness monitor is incorporated into the vacuum film forming apparatus for use. In order to prevent the salicylic acid from melting by preventing the temperature rise of the wavelength conversion unit 411, it is important to take a heat-proof measure. In the vacuum ultraviolet optical film thickness monitor of the present invention, in order to solve this problem, the cooling water circulation path 413 is used.
In addition to cooling water by cooling water to cool the wavelength conversion part, the substrate to which salicylic acid is applied is magnesium fluoride (MgF).
₂ ) and a device for forming a thin film 416 for cutting light having a long wavelength longer than visible light is formed on one surface of the MgF ₂ plate.

When light having a wavelength in the vacuum ultraviolet to far infrared region is incident on the light receiving portion having such a structure, first, the thin film 416 cuts most of the light having a wavelength longer than visible light, and further, the MgF ₂ plate. Most light having a wavelength of approximately 400 nm or more is cut by 414. Therefore, only light having a wavelength of 400 nm or less enters the salicylic acid coating layer 415.

FIG. 5 is a diagram for explaining the light transmission characteristics of the MgF ₂ plate and the thin film portion deposited on one surface of the MgF ₂ plate of the light-receiving unit constructed in this manner. The wavelength range from vacuum ultraviolet to far infrared region. Of the light having a wavelength of 130 to 400 nm is transmitted, and when light in this wavelength region enters the coating layer of salicylic acid, the reaction between salicylic acid and vacuum ultraviolet light causes a change in the wavelength range from ultraviolet to vacuum ultraviolet. The light will be converted to visible light.

FIG. 6 is a diagram for explaining a fluorescence spectrum when the salicylic acid coating layer is irradiated with light in the wavelength region of 130 to 400 nm having the intensity distribution shown in FIG. 5, and a wavelength shorter than 350 nm. Light is converted into visible light within the salicylic acid coating layer, resulting in 420n
A fluorescence spectrum is obtained which has a peak in the vicinity of m and covers a wavelength region of approximately 0.35 to 0.55 μm.

FIG. 4B is a view for explaining another example of the structure of the light receiving portion provided in the VUV optical film thickness monitor of the present invention, and the wavelength converting portion 4 housed in the holding member 420.
21, a condenser lens 422, and a light guide 423 to the optical fiber. Inside the holding member 420, a cooling water circulation passage 424 for preventing the temperature rise of the wavelength conversion unit 421 is provided.

The condenser lens 422 is made of magnesium fluoride (MgF ₂ ), which cuts the light having a wavelength of 400 nm or more out of the light incident on the light receiving portion and only the light having a wavelength of 400 nm or less. Wavelength converter 42
It is possible to collect light at 1. The wavelength conversion unit 421,
It is composed of a quartz plate 425 and a salicylic acid coating layer 426 coated on one side thereof.
26 makes it possible to convert ultraviolet light to vacuum ultraviolet light having a wavelength of 350 nm or less into visible light.

By using the light-receiving section having such a structure, the temperature of the light-receiving section is prevented from rising due to the light emitted from the measurement environment, the deterioration of the salicylic acid coating layer 426 is prevented, and the light from the measurement sample is measured. The signal light can be efficiently guided to the optical fiber by the condenser lens 422.

As described above, in the vacuum ultraviolet optical film thickness monitor of the present invention, in order to avoid absorption of vacuum ultraviolet light by air, all optical system components such as a light source, a monochromator and a mirror are housed in a vacuum container. Then, the signal light from the measurement sample is received by the light receiving portion arranged in the vicinity thereof and guided to the outside of the vacuum container by the optical fiber, and further, in order to avoid the attenuation of the signal intensity in the optical fiber, Converts ultraviolet light into visible light by the wavelength conversion unit provided in the light receiving unit,
The visible light intensity can be analyzed as the signal light intensity.

As a result, the spectrum analysis of vacuum ultraviolet light, which has been obtained only with a low S / N by the conventional optical film thickness monitor, can be performed under the condition of a high S / N, and the stable spectrum analysis can be easily performed. At the same time, the manufacturing cost can be significantly reduced by simplifying the device configuration.

[Embodiment 2] FIG. 7 is a view for explaining another configuration example of the vacuum ultraviolet optical film thickness monitor of the present invention. The vacuum ultraviolet optical film thickness monitor 700 is housed in a vacuum container 701. Ultraviolet to vacuum ultraviolet light source 702 and condenser lens 70
3 and the diffraction grating 7 provided in the monochromator 704.
05, a mirror 706 arranged to irradiate the measurement sample 708 with light from the light source 702, and a concave mirror 7
07, a light receiving unit 709 that receives the reflected light from the measurement sample 708 and converts vacuum ultraviolet light into visible light, and a light receiving unit 709.
Between the light source 702 and the monochromator 704, in addition to the optical fiber 710 for guiding the visible light converted by the light to the outside of the vacuum container 701 and the sensor 711 for recognizing the light intensity guided by the optical fiber 710. A chopper 718 driven by a motor 717 provided in the optical path, a semi-transparent mirror 719 provided in the optical path between the diffraction grating 705 and the mirror 706, and a reference light reflected by the semi-transparent mirror 719 are received to generate a vacuum. Reference light receiving unit 720 for converting ultraviolet light into visible light
An optical fiber 721 for guiding the visible light converted by the reference light receiving unit 720 to the outside of the vacuum container 701, a sensor 722 for recognizing the light intensity guided by the optical fiber 721, and a light source power supply 712. And a vacuum pump 713 for creating a high vacuum inside the vacuum container 701, and further, this vacuum ultraviolet optical film thickness monitor 700.
A lock-in amplifier 714 for amplifying the output signals of the sensors 711 and 722, an A / D converter 715 for converting an analog signal into a digital signal, and a spectrum analysis process by processing the digital signal. A spectroscopic system is configured by the PC 716 for execution.

The basic operating principle of the VUV optical film thickness monitor of the present embodiment is substantially the same as that of the VUV optical film thickness monitor described in the first embodiment, but the VUV optical film of the present embodiment is operated. In the film thickness monitor, a chopper 718 driven by a motor 717 is provided in the optical path between the light source 702 and the monochromator 704, and a semi-transparent mirror 71 is provided in the optical path between the diffraction grating 705 and the mirror 706.
9 is provided. The light emitted from the light source 702 is incident on the measurement sample 708 while being intermittently blocked by the chopper 718 rotating at a constant speed, and the reflected light is guided to the sensor 711 as signal light.

On the other hand, the reference light reflected by the semi-transparent mirror 719 is received by the reference light receiving section 720 having the same structure as the signal light receiving section 709 and converted into visible light, and is transmitted to the sensor 722 by the optical fiber 721. After being guided and recognized as a reference light signal, it is transmitted to the PC 716 via the lock-in amplifier 714 and the A / D converter 715. The PC 716 that receives the reference light signal calculates a difference between the light intensity of the time interval in which the reference light is received by the reference light receiving unit 720 and the light intensity of the time interval in which the reference light is blocked by the chopper 718, The difference makes it possible to obtain the true signal light intensity from the measurement sample 708.

FIG. 8 is a diagram for explaining the temporal change of the light intensity input to the PC which is the signal processing means of the spectroscopic system constituted by the vacuum ultraviolet optical film thickness monitor of the present invention. Is. The light intensity received by the sensor is caused by the light from the light source being interrupted intermittently by the chopper, resulting in the intensity of the signal light obtained from the measurement sample and stray light that is not the original signal light being received by the optical fiber. It is detected as the sum of light intensity corresponding to noise or electrical noise. Of these, the noise component has a constant intensity throughout the measurement, whereas the intensity component of the signal light is detected only while the light from the light source is being applied to the measurement sample. By causing the PC to perform the operation of removing the noise component from the intensity, it becomes possible to extract only the true signal light intensity.

As described above, the chopper for interrupting the light from the light source intermittently and the reference light receiving portion for receiving the reflected light from the semi-transparent mirror are provided, and the signal light intensity from the measurement sample,
With the configuration in which the difference with the reference light intensity received by the reference light receiving unit is calculated, only the true signal light intensity from the measurement sample of the intensity of the received light is extracted, and S
It is possible to significantly improve / N.

[Third Embodiment] The film thickness of the optical film formed on the measurement sample is calculated by analyzing the intensity of the signal light in the vacuum ultraviolet region detected by the vacuum ultraviolet optical film thickness monitor of the present invention. It becomes possible.

The phase difference of the signal light reflected (or transmitted) through the thin film is due to the interference action of the reflected light generated on the front and back surfaces of the thin film when the irradiation light reflects (or transmits) the thin film.
It changes periodically with the optical thickness of the thin film, and the optical thickness is λ
It takes the maximum value or the minimum value (signal peak) when it corresponds to an integral multiple of / 4. This phenomenon is the most important basic principle in the optical thin film design, the so-called “λ / 4 rule”.
Is widely known as. For example, in the case where each thin film forms a multilayer film having an optical film thickness of λ / 4, a signal intensity peak appears for each optical film thickness corresponding to λ / 4. The change can be used to calculate the optical film thickness.

Therefore, if the PC for the VUV optical film thickness monitor shown in FIG. 1 or FIG. 7 is used to execute the calculation for calculating the optical film thickness, the film thickness of the optical film is automatically measured. It becomes possible.

[Embodiment 4] FIG. 9 is a diagram for explaining a configuration example of a vacuum film forming apparatus of the present invention, which is composed of a vacuum film forming unit 900 and a spectral system unit 910 for film thickness monitoring.
A part of the vacuum container 911 of the spectroscopic system unit 910 is jointed to a hole provided above the vacuum partition 901 of the vacuum film forming unit 900 so as to maintain a vacuum.

The inside of the vacuum partition 901 and the vacuum container 911 is a vacuum pump 902 provided in the vacuum film forming unit 900.
It is possible to maintain a high vacuum by means of the above, and the metal film 905 is supplied from the sputtering device 904 onto the film formation surface of the substrate 903 placed in the vacuum partition 901 to form a metal film. It

On the other hand, the ultraviolet-vacuum ultraviolet light emitted from the light source 912 is condensed by a condenser lens 913 and then intermittently interrupted by a chopper 919 which rotates at a constant speed by a motor 918, while a monochromator 914. Only a desired monochromatic light is selected by the diffraction grating 915 provided in, and the monochromatic light is reflected by the mirror 916 and the concave mirror 917 and is incident on the measurement surface of the substrate 903. The signal light from the substrate 903, which is the measurement sample, is received by the light receiving unit 920 arranged in the vicinity of the substrate 903, and guided to the sensor 922 by the optical fiber 921. Further, the reference light reflected by the semi-transparent mirror 923 is received by the reference light receiving section 924 having the same configuration as the signal light receiving section 920, converted into visible light, and guided to the sensor 926 by the optical fiber 925. After being recognized as a reference light signal, the light is transmitted to the PC 929 via the lock-in amplifier 927 and the A / D converter 928. The PC 929 that receives the reference light signal calculates the difference between the light intensity of the time interval in which the reference light is received by the reference light receiving unit 924 and the light intensity of the time interval in which the reference light is blocked by the chopper 919, The difference makes it possible to obtain the true signal light intensity from the measurement sample 908.

If the signal light intensity is calculated based on such a difference, light in various wavelength regions emitted from the sputtering apparatus 904 or the like is generated during film formation in the vacuum film formation unit 900, Even if these lights pass through the substrate 903 and enter the light receiving unit 920 to generate noise, the noise can be removed and only the true signal light intensity can be detected.

The PC 929 performs an analysis process for calculating a physical quantity corresponding to the optical film thickness of the film being formed on the substrate 903 based on the thus obtained difference in light intensity, and outputs a signal for each runtime. The thickness of the thin film formed on the substrate 903 is calculated based on the light intensity, and the vapor deposition target is switched to allow the next thin film to be formed or the film formation to be stopped in accordance with the previously designed designed film thickness. The vacuum film forming unit 9 sends a signal to
00 to the control device.

As described above, by incorporating the vacuum ultraviolet optical film thickness monitor of the present invention into the vacuum film forming apparatus, it becomes possible to perform film formation while monitoring the optical film thickness of the thin film during vacuum film formation. It is possible to obtain an optical film whose film thickness exactly matches the designed value.

[0053]

As described above, in the vacuum ultraviolet optical film thickness monitor of the present invention, in order to suppress the decrease in the signal light amount in the vacuum ultraviolet region, the mirrors and lenses of the vacuum ultraviolet optical film thickness monitor are controlled. The optical system is made as few as possible, and the signal light is received by the light receiving unit equipped with the wavelength conversion unit, and the received signal light of the wavelength range from ultraviolet to vacuum ultraviolet is composed of a salicylic acid-coated quartz plate or magnesium fluoride plate. The wavelength conversion unit converts the light into the visible range and the converted visible light is detected by the sensor.Therefore, it is possible to detect signal light with a wavelength in the vacuum ultraviolet range with high sensitivity. A film thickness monitor can be obtained.

Further, since the temperature rise of the wavelength conversion part due to the radiation light other than the signal light is prevented, the vacuum ultraviolet optical film thickness monitor which can be used even in the vacuum film forming apparatus having a high temperature environment of 200 ° C. or higher. Is obtained.

Further, since the PC for automatically calculating the film thickness of the optical film based on the signal from the vacuum ultraviolet optical film thickness monitor having such a configuration is provided, the optical device for the next-generation stepper is provided. It is possible to monitor the film thickness of a multilayer film or the like when manufacturing a lens.

Further, by incorporating such a vacuum ultraviolet optical film thickness monitor into the vacuum film forming apparatus, a vacuum film forming apparatus capable of forming a film while monitoring the film thickness of an optical film to be formed is obtained. To be

[Brief description of drawings]

FIG. 1 is a diagram for explaining the configuration of a VUV optical film thickness monitor of the present invention.

FIG. 2 is a diagram for explaining a light intensity distribution of a heavy water lamp used as a light source of the vacuum ultraviolet optical film thickness monitor of the present invention.

FIG. 3 is a diagram for explaining a loss of light propagating in an optical fiber.

FIG. 4 is a diagram for explaining a configuration example of a light receiving unit included in the VUV optical film thickness monitor of the present invention, in which (a) increases the temperature of the light receiving unit due to radiant heat of light emitted from the measurement environment. 2B shows a light receiving unit configured to suppress such temperature rise, and FIG. 6B illustrates a light receiving unit configured to suppress such temperature rise and efficiently guide the signal light from the measurement sample to the optical fiber. Shows.

FIG. 5 is a diagram for explaining light transmission characteristics of a MgF ₂ plate and a thin film portion deposited on one surface of the MgF ₂ plate of the light receiving unit provided in the VUV optical film thickness monitor of the present invention.

FIG. 6 shows a salicylic acid coating layer having a wavelength range of 130 to 400.
It is a figure for demonstrating the fluorescence spectrum at the time of irradiating with the light of nm.

FIG. 7 is a diagram for explaining another configuration of the VUV optical film thickness monitor of the present invention.

FIG. 8 is a diagram for explaining a temporal change in light intensity input to a PC that is a signal processing unit in a spectroscopic system including the VUV optical film thickness monitor of the present invention.

FIG. 9 is a diagram for explaining the configuration of the vacuum film forming apparatus of the present invention.

FIG. 10 is a diagram for explaining a configuration of a conventional optical film thickness monitor and a spectroscopic system including the same.

[Explanation of symbols]

11, 102, 702, 912 Light source 12, 103, 703, 913 Condensing lens 13a-d, 106, 107, 706, 707, 91
6,917 Mirror 14, 108, 708 Measurement sample 15, 104, 704, 914 Monochromator 16 Photodetector 17, 115, 715, 928 A / D converter 18, 116, 716, 929 PC 100, 700 Vacuum UV optics Film thickness monitor 101, 701, 911 Vacuum container 105, 705, 915 Diffraction grating 109, 709, 920 Light receiving part 110, 710, 721, 921, 925 Optical fiber 111, 711, 722, 922, 926 Sensor 112, 712 For light source Power source 902 Vacuum pump 114 Amplifiers 410, 420 Holding members 411, 421 Wavelength converters 412, 423 Light guides 413, 424 Cooling water circulation path 414 Magnesium fluoride plates 415, 426 Coating layer 416 Thin film 422 Condensing lens 425 Quartz plates 714, 924 Lock in It flops 717,918 motor 718,919 chopper 719,923 semitransparent mirror 720,924 reference light receiving unit 900 vacuum deposition section 901 vacuum partition wall 903 substrate 904 sputtering system 905 deposited metal 910 spectroscopic system unit

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2F065 AA30 DD04 DD17 FF46 GG00                       HH04 HH12 JJ01 JJ09 LL02                       LL12 LL23 LL30 LL42 QQ03                       QQ07                 2H048 CA05 CA09 CA12 CA14 CA17                       CA23 CA29                 4K029 AA04 BA01 BA03 BB02 BC08                       BD00 CA05 EA01

Claims (5)

[Claims] 1. A light source that emits light in the ultraviolet to vacuum ultraviolet region, a spectroscopic means for irradiating the measurement sample with the light emitted from the light source, and signal light in the ultraviolet to vacuum ultraviolet region from the measurement sample. A vacuum ultraviolet optical film comprising: a light receiving unit having a visible light converting unit for converting the light into visible light; and a signal light detecting unit for receiving the visible light converted by the light receiving unit and detecting a signal. Thickness monitor. 2. The vacuum ultraviolet optical film thickness monitor according to claim 1, wherein the visible light converting means is a quartz plate coated with salicylic acid or a magnesium fluoride plate coated with salicylic acid. 3. A chopper provided in the optical path between the light source and the spectroscopic means, a semi-transparent mirror provided in the optical path between the spectroscopic means and the measurement sample, and a semi-transparent mirror from the semi-transparent mirror. Reference light receiving means for receiving the reflected light, signal processing means for calculating the difference between the signal light detected by the signal light detecting means and the reference light detected by the reference light receiving means. The vacuum ultraviolet optical film thickness monitor according to claim 1 or 2. 4. A vacuum ultraviolet optical system comprising: the vacuum ultraviolet optical film thickness monitor according to claim 1; and film thickness calculating means for calculating an optical film thickness of a measurement sample based on a change in intensity of signal light. A vacuum ultraviolet optical film thickness monitoring system, wherein the optical film thickness of the measurement sample is calculated based on a signal output from a film thickness monitor. 5. A vacuum film forming apparatus comprising vacuum film forming means and the vacuum ultraviolet optical film thickness monitoring system according to claim 4, wherein a measurement sample is arranged at a film forming sample position of said vacuum film forming means. Then, the vacuum film forming apparatus is characterized in that the film is formed while monitoring the optical film thickness of the measurement sample.