JP2001272303A - Fiber degradation detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber degradation detecting device, capable of effectively detecting degradation of an optical fiber and realizing a quick replacement of the fiber. SOLUTION: Degradation of a first optical fiber 8a or a second optical fiber 9a is always detected by a degradation detecting part 19. When one is detected, an optical path switching command is given to optical path switching parts 16, 17 and 18, to automatically switch the first optical fiber 8a and the second optical fiber 9a into the first replaced optical fiber 8a and the second replaced optical fiber 9b, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a fiber deterioration detecting apparatus for detecting deterioration of an optical fiber incorporated in semiconductor manufacturing equipment such as an etching apparatus and a substrate inspection apparatus.

[0002]

2. Description of the Related Art Recently, a semiconductor manufacturing apparatus and an inspection apparatus have been installed in a clean room where the surrounding environment is controlled, and have been operated continuously without human intervention.

FIG. 10 shows a schematic configuration of an etching apparatus which is an example of a semiconductor manufacturing apparatus installed in such a clean room. In the drawing, reference numeral 1 denotes an etching chamber, and the inside of the etching chamber 1 is filled with an etching gas. An upper electrode 2 and a lower electrode 3 are arranged inside the etching chamber 1 so as to face each other. On the lower electrode 3, a high-frequency power source 4 is connected and a substrate 5 to be etched such as a wafer is connected. Is placed. An observation window 6 made of quartz glass is provided at an upper portion of the etching chamber 1. In such an etching apparatus, the substrate 5 to be etched is placed on the lower electrode 3, the inside of the etching chamber 1 is evacuated, and then the etching gas is filled. Then, a high-frequency electric field is applied to the upper electrode 2 and the lower electrode 3 by the high-frequency power supply 4 to generate plasma in the etching chamber 1. As a result, when the plasma reaches the surface of the substrate 5 to be etched, a surface reaction is caused by ions and radical particles in the plasma flow, and the surface of the substrate 5 to be etched is etched.

On the other hand, such an etching apparatus is provided with an etching depth measuring apparatus for measuring the etching depth of the surface of the substrate 5 to be etched. The etching depth measuring apparatus includes a first optical fiber 8 for irradiating light from a direction perpendicular to the surface of the substrate 5 to be etched and the reflected light from the surface of the substrate 5 to be etched outside the observation window 6 of the etching chamber 1 The second optical fibers 9 for receiving light are arranged side by side. The first optical fiber 8 is connected to a light source 7 composed of a Xe lamp on the base end side, and emits light emitted from the light source 7 toward the substrate 5 to be etched from the distal end. A spectroscope (monochromator) 10 is connected to the base end of the second optical fiber 9, and reflected light from the surface of the substrate 5 to be etched, which is received at the tip, is incident on the spectroscope 10.
The spectroscope 10 splits the reflected light and outputs an electric signal corresponding to the received light intensity of the designated wavelength. And, in the spectroscope 10,
The depth calculation device 11 is connected, and the etching depth is obtained from an electric signal indicating the received light intensity of the reflected light of the designated wavelength.

By the way, the first and second optical fibers 8 and 9 used in such an etching depth measuring device.
It is known that the spectral transmittance is deteriorated by ultraviolet light of plasma generated at the time of etching, and in particular, as shown in FIG. 11, the spectral transmittance is significantly deteriorated in an ultraviolet region. When the spectral transmittance of the optical fibers 8 and 9 deteriorates, the S / N ratio decreases due to the attenuation of the intensity of light reflected by the spectroscope 10 from the surface of the substrate 5 to be etched. Since the peak position of the reflected interference wave cannot be determined, there arises a problem that accurate etching depth measurement becomes difficult.

Therefore, conventionally, the deterioration of the spectral transmittance of the optical fibers 8 and 9 has been detected by some detecting means.
It is necessary to replace the deteriorated optical fiber promptly,
For this reason, a method has been adopted in which the effective use period of the optical fiber is determined in advance, and the optical fiber that has passed this period is regarded as deteriorating and responds to fiber replacement.

[0007]

However, according to such a method, the required replacement time and the predetermined replacement time do not actually coincide with each other because the spectral intensity distribution of the emitted plasma differs depending on the type of etching. There is also a problem that sudden accidents such as sudden deterioration or cutting of the optical fiber cannot be dealt with at all. In addition, in the replacement of the optical fiber, the worker stops the operation of the apparatus and enters the clean room to perform the work, so that the yield of the product is reduced due to the influence of dust from the worker. In addition, there is a problem that the operation of the apparatus must be continuously stopped during the operation of replacing the fiber, resulting in a significant decrease in operation efficiency. If there is no spare optical fiber for replacement, it takes time to obtain the optical fiber, during which time the apparatus must be stopped. Furthermore, in semiconductor manufacturing related equipment operating unattended, if operation is continued without knowing that an optical fiber failure has occurred, manufacturing and
As for the inspected products, there is a problem that many defective products are generated.

[0008] This is not limited to the above-described etching apparatus, but is a common problem with all other manufacturing apparatuses and defect inspection apparatuses that continuously operate without stopping the production line, using optical fibers. Was there.

The present invention has been made in view of the above circumstances, and it is possible to efficiently detect deterioration of an optical fiber,
It is an object of the present invention to provide a fiber deterioration detection device that realizes quick fiber exchange.

[0010]

According to the first aspect of the present invention,
An optical fiber that guides light; a fiber deterioration determining unit that detects the intensity of light guided through the optical fiber to determine fiber deterioration; and a defect on an optical path that is determined by the fiber deterioration determining unit using the fiber deterioration determining unit. Fiber switching means for automatically switching an optical fiber to a new optical fiber.

According to a second aspect of the present invention, in the first aspect of the present invention, the fiber deterioration judging means sets the transmittance of the optical fiber to be lower than the light guided through the optical fiber due to the deterioration of the optical fiber. A first wavelength that does not decrease and a second wavelength that deteriorates the optical fiber are separated, and a relative intensity I1 of the first wavelength when normalized by the second wavelength and a relative intensity I2 obtained in a normal state. Fiber degradation is determined when the ratio I2 / I1 with respect to the threshold value becomes lower than the specified threshold value.

The invention described in claim 3 is the first or second invention.
In the invention described above, the fiber switching means arranges at least two optical fibers side by side, and positions a new optical fiber on an optical path by judging fiber deterioration by the fiber deterioration judging means.

The invention according to claim 4 is the first or second invention.
In the described invention, the fiber switching means has an optical fiber disposed on an optical path and another optical fiber disposed at a predetermined angle with respect to the optical path,
It has an optical path deflecting member that can be inserted into and removed from the optical path, and the fiber deterioration is determined by the fiber deterioration determining means.
The other optical fiber is positioned on the optical path via the optical path deflecting member.

As a result, according to the present invention, the deterioration of the optical fiber located on the optical path can always be detected, so that sudden accidents such as rapid deterioration or breakage of the fiber can be promptly dealt with. In addition, when fiber deterioration is detected, the defective optical fiber on the optical path is automatically switched to a new optical fiber, so that the clean room is not affected by dust from workers, and unattended. In the semiconductor manufacturing related equipment described above, the spare optical fiber can be promptly exchanged, so that the reliability of the apparatus can be improved.

Further, according to the present invention, fiber switching can be performed only by changing the positions of the optical fibers arranged side by side, so that the configuration of each optical path switching unit can be simplified.

Further, according to the present invention, since the fiber can be switched only by the operation of the reflecting mirror which can be inserted into and removed from the optical path, the configuration of each optical path switching section can be simplified.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a schematic configuration of an etching apparatus which is one of semiconductor manufacturing equipment to which the present invention is applied, and the same parts as those in FIG. are doing.

In this case, an optical section 14 is provided in the observation window 6 of the etching chamber 1. This optical unit 14
For example, the illumination light from the light source 7 composed of a Xe lamp generated from the ultraviolet region to the near-infrared region and the illumination light from the light source 7 along the optical path of the reflected light from the substrate 5 to be etched are made parallel light, A condenser lens 12 for condensing reflected light from the substrate 5 to be etched and a reflecting mirror 13 which is an optical path deflecting member coated with an Al (aluminum) coating having excellent reflectance for ultraviolet light are arranged. Reflector 1
Numeral 3 is removably inserted into and removed from the optical path, is retracted from the optical path to a position shown by a broken line in the state where normal etching is performed, and is positioned on the optical path at the time of a fiber deterioration inspection. I have.

The optical unit 14 includes the condenser lens 1
An optical path switching unit 16 is provided at the second focal position. As shown in FIG. 2A, at least two optical path switching units 16, here first optical fibers 8a and 8b, are arranged side by side on a slide member 16a slidable in the direction of the arrow shown in FIG. One optical fiber 8a,
8b, the second optical fibers 9a and 9b are arranged side by side and one set of spare optical fibers 9a and 9b is prepared. As shown in FIG. The optical fiber 9a is positioned on the optical path of the condenser lens 12, and the slide from the state where the reflected light from the substrate 5 to be etched condensed by the condenser lens 12 via the second optical fiber 9a is received. The member 16a is slid and switched to the spare first optical fiber 8b and the spare second optical fiber 9b, so that the substrate to be etched 5 condensed by the condenser lens 12 via the second optical fiber 9b. Reflected light can be received. The slide member 16a is provided so as to be reciprocally movable by a linear guide, and can be automatically switched by a drive unit such as a solenoid.

The first optical fibers 8a and 8b are provided with an optical path switching section 17 provided with an automatic switching mechanism similar to the optical path switching section 16 in the optical path between the light source 7 and the first optical fibers 8a and 8b. The optical path switching unit 17 switches an optical path between the light source 7 and the first optical fibers 8a and 8b in conjunction with an optical path switching operation of the optical path switching unit 16. Further, the second optical fibers 9a and 9b are provided with an optical path switching unit 18 provided with an automatic switching mechanism similar to the optical path switching unit 16 described above in the optical path between the second optical fibers 9a and 9b. This optical path switching unit 1
Numeral 8 switches the optical path between the second optical fibers 9a and 9b and the spectroscope 10 in conjunction with the optical path switching operation of the optical path switching unit 16.

The spectroscope 10 splits the reflected light and outputs an electric signal corresponding to the intensity of the received light at the designated wavelength. A depth calculator 11 is connected to the spectroscope 10, and the etching depth is obtained from an electric signal indicating the received light intensity of the reflected light of the designated wavelength.

Further, the spectroscope 10 is provided with a deterioration detecting section 19. As shown in FIG. 3, the deterioration detecting section 19 transmits the first optical signal through a filter 192 to the transmission optical path of the half mirror 191 where the second optical fiber 9a (9b) is incident.
Of the half mirror 1
A second detector 196 is arranged via a filter 195 on the reflection optical path of the mirror 194 on which the reflection light of 91 is incident. The first detector 193 detects the spectral intensity A at a wavelength of, for example, 219 nm, whose transmittance is known to decrease due to fiber degradation, and the second detector 196 does not exhibit a decrease in transmittance due to fiber degradation. For example, wavelength 35
It detects the spectral intensity B of 0 nm. And the outputs of these first and second detectors 193, 196 are:
It is input to the deterioration determination unit 197. The deterioration determination unit 197
Based on the relative intensity I = (A / B) at the wavelength of 219 nm normalized from the output of the first and second detectors 193 and 196 at the wavelength of 350 nm, the relative intensity I2 at the time of deterioration detection is measured. And the ratio I2 / I to the relative intensity I1 measured beforehand immediately after the replacement of the optical fiber.
1 is obtained, and when this ratio becomes lower than a predetermined threshold value, for example, when the exchange determination value becomes 70% or less from the relationship of I2 / I1 ≦ 70% (exchange determination value), fiber deterioration is determined. I am trying to do it.

When the deterioration is judged by the deterioration judging section 197, an optical path switching command is output to each of the optical path switching sections 16, 17, and 18, and a warning for prompting the replenishment of the spare optical fiber is output. The warning turns on the lamp and turns off the warning lamp when the defective optical fiber is replaced with a new spare optical fiber. In this case, it is preferable to provide a warning lamp for each spare optical fiber.

Next, the operation of the embodiment configured as described above will be described.

In the etching apparatus, the substrate 5 to be etched is placed on the lower electrode 3, the inside of the etching chamber 1 is evacuated, and then the etching gas is filled. Then, a high-frequency electric field is applied to the upper electrode 2 and the lower electrode 3 by the high-frequency power supply 4 to generate plasma in the etching chamber 1. As a result, when the plasma reaches the surface of the substrate 5 to be etched, a surface reaction is caused by ions and radical particles in the plasma flow, and the surface of the substrate 5 to be etched is etched.

In this state, the etching depth is measured. In this case, the first optical fiber 8a and the second optical fiber 9a are used for the etching depth measurement, and the reflecting mirror 13 of the optical unit 14 is retracted from the optical path to a position shown by a broken line in the drawing.

When the light source 7 is turned on, light emitted from the light source 7 is incident on the optical section 14 through the first optical fiber 8a, passes through the condenser lens 12 and becomes parallel light, Substrate 5 to be etched through observation window 6
Is irradiated. The reflected light from the substrate 5 to be etched is collected by the condenser lens 12 through the observation window 6,
The light enters the spectroscope 10 via the second optical fiber 9a. The spectroscope 10 splits the reflected light and outputs an electric signal according to the received light intensity of the designated wavelength, and the electric signal is sent to the depth calculating device 11, and the received light intensity of the reflected light of the designated wavelength at this time is calculated. The etching depth is determined from the electric signal shown.

In this case, FIG. 4 shows the reflected light from the substrate 5 to be etched, and the time t1 to advance one cycle of the waveform is obtained from the peak interval of the reflected light waveform. Is determined as m = t / t1. FIG. 5 is a sectional view of the substrate 5 to be etched at this time.
Is shown in In this case, reference numeral 704 denotes a SiO ₂ mask portion, and reference numeral 705 denotes a Si substrate. When light is irradiated from the upper surface of the substrate 5 to be etched, there are surfaces 701, 702, and 703 as reflection surfaces.
2, 703 interference light is dominant, and the optical path length difference change amount is Δ (ΔS) = 2 (d1 + Δd2) −2 (n1d1) = m
λ. Here, d1 is the film thickness of the mask portion 704, and is not changed by etching. d2 is the etching depth, n1 is the refractive index of the mask section 704, and λ is the wavelength of light split by the spectroscope.

Thus, the etching depth Δd2 can be calculated by obtaining the current period m of the reflected light waveform. Then, the etching depth Δd2 is calculated. When the predetermined depth is measured and the end point is reached, the high-frequency power supply 4 is shut off, and the etching ends.

Next, a case where fiber deterioration is detected in such an etching apparatus will be described.

In this case, the reflecting mirror 13 of the optical section 14 is located on the optical path. When the light source 7 is turned on, the light source 7
The light emitted from the first optical fiber 8a is incident on the optical unit 14 through the first optical fiber 8a, and is reflected by the reflecting mirror 1 before the condenser lens 12.
3 is reflected on the second optical fiber 9a.
And is guided to the spectroscope 10.

In the spectrometer 10, the first detector 193 of the deterioration detector 19 detects a spectral intensity A at a wavelength of 219 nm, for example, at which the transmittance is known to decrease due to the fiber deterioration, and the second detector 196 detects the fiber deterioration. For example, a spectral intensity B at a wavelength of 350 nm at which no decrease in transmittance is observed is detected. Then, when the outputs of the first and second detectors 193 and 196 are input to the deterioration determining unit 197, the first and second detectors 193 and 196 are input.
Wavelength 21 when normalized at the wavelength of 350 nm from the output of
Based on the relative intensity I of 9 nm = (A / B), the relative intensity I2 at the time of the deterioration detection is measured, and the relative intensity I1 previously measured in the normal state immediately after the replacement of the optical fiber.
When the ratio I2 / I1 reaches the replacement determination value 70%, it is determined that the fiber has deteriorated. When the deterioration determination unit 197 determines that the fiber has deteriorated, the optical path switching unit 16 , 17 and 18 are output with an optical path switching command. Then, in the optical path switching unit 16,
The slide member 16 is slid and the focusing lens 12 is moved.
The defective optical fiber 8a located on the optical path with respect to is switched to the new first optical fiber 8b, and at the same time, the defective optical fiber 9a located on the optical path for receiving the reflected light from the substrate 5 to be etched is also changed. Switching to a new second optical fiber 9b is performed. Further, in conjunction with the optical path switching operation by the optical path switching section 16, the defective optical fiber 8a connected to the light source 7 is also switched by the optical path switching section 17 to a new first optical fiber 8a. Also, the defective optical fiber 9a connected to the spectroscope 10 is switched to a new second optical fiber 9b.

Accordingly, in this case, the deterioration detecting section 1
9, the first optical fiber 8a positioned on the optical path
In addition, since deterioration of the second optical fiber 9a can be detected constantly or periodically, sudden accidents such as abrupt deterioration of the fiber can be dealt with promptly as compared with the conventional method in which replacement is performed with fixed replacement time. And the fiber can be used effectively up to the life limit of the fiber.

When the deterioration detecting section 19 detects the deterioration of the fiber being used, each of the optical path switching sections 16, 1
An optical path switching command is given to 7, 18 and the first optical fiber 8a and the second optical fiber 9a determined to be defective are automatically added to the new first optical fiber 8b and new optical fiber 9b, respectively. Since switching can be performed, compared with the conventional optical fiber replacement, workers stop operation of the equipment and work inside the clean room, compared to the effects of dust generation from workers in the clean room. This reduces the risk of product yield, reduces the yield of products, and makes it possible to switch fibers instantaneously without stopping or short-term operation of the equipment. And the work efficiency can be greatly improved.

(Second Embodiment) FIG. 6 shows a schematic configuration of a second embodiment of the present invention, and the same parts as those in FIG. 1 are denoted by the same reference numerals.

In this case, the optical section 14 includes the condenser lens 12
In addition, a silicon substrate 21 before forming a thin film instead of the reflecting mirror 13 is mounted on the lower electrode 3 disposed in the etching chamber 1.

In such a configuration, when fiber deterioration is detected, light emitted from the light source 7 is incident on the optical section 14 through the first optical fiber 8a (8a), and the silicon in the etching chamber 1 is Irradiated on the substrate 21,
Here, the light is reflected and guided to the spectroscope 10 through the second optical fiber 9a (9b). In the same manner as described above, the deterioration detector 19 determines the fiber deterioration.

In this manner, the fiber deterioration can be easily detected only by placing the silicon substrate 21 before the thin film is formed on the lower electrode 3, so that the configuration for detecting the fiber deterioration can be simplified. The size of the device can be reduced.

(Third Embodiment) FIG. 7 shows a schematic configuration of a third embodiment of the present invention, and the same parts as those in FIG. 1 are denoted by the same reference numerals.

In this case, a U-shaped optical fiber 22 is disposed in the optical section 14 as an optical path deflecting member, the optical fiber 22 being movable in the direction indicated by an arrow perpendicular to the optical path for the condenser lens 12. The U-shaped optical fiber 22 is evacuated from the optical path during normal etching, and is inserted into the optical path at the time of fiber deterioration inspection.

When simultaneously detecting the deterioration of the first optical fiber 8a (8b) and the second optical fiber 9a (9b), the U-shaped optical fiber 22 is connected to the first optical fiber 8a.
a (8b) and the distal end of the second optical fiber 9a (9b) are optically connected to each other, and the first optical fiber 8a (8
b) the light introduced via the second optical fiber 9
a (9b), and when only the deterioration of the first optical fiber 8a (8b) is detected, the U-shaped optical fiber 22 is positioned on the left side of the optical path in the drawing and the light source 7 In order to detect the light introduced from the first optical fiber 8a (8b) through the first optical fiber 8a (8b) into the deterioration detecting unit 23, and to detect only the deterioration of the second optical fiber 9a (9b), a U-shaped The optical fiber 22 is located on the right side of the drawing with respect to the optical path so that light from the light source 24 is directly incident on the second optical fiber 9a (9b). The deterioration detection unit 23 in this case is similar to the deterioration detection unit 19 described above.

Accordingly, in this way, only by selecting the position of the U-shaped optical fiber 22 on the optical path, the first optical fiber 8a (8b) and the second optical fiber 9a
Not only can the deterioration of (9b) be detected simultaneously, but also the first optical fiber 8a (8b) and the second optical fiber 9a
Since deterioration detection of only one of (9b) can be performed, efficient fiber deterioration detection can be performed by selecting a detection method according to the use condition of the device.

Although the U-shaped fiber 22 is used in the above description, a similar effect can be expected by using a triangular prism instead.

(Fourth Embodiment) FIGS. 8 and 9 show
FIG. 14 shows a schematic configuration of an optical path switching unit used in a fourth embodiment of the present invention. In this case, the schematic configuration of the etching apparatus is the same as that of FIG.

In this case, the optical section 14 provided in the observation window 6 of the etching chamber 1 is provided with a first optical fiber 8a disposed on the optical path of the condenser lens 12 as shown in FIG.
And the other first optical fiber 8b disposed at an angle of about 90 ° with respect to the optical path, and a reflecting mirror 31 that can be inserted into and removed from the optical path.
Is moved to the position indicated by the broken line in the drawing, and by moving the reflection mirror 31 on the optical path from the state where the first optical fiber 8a is located on the optical path of the condenser lens 12, another reflection via the reflection mirror 31 is performed. The first optical fiber 8b is connected to the condenser lens 1
2 on the optical path. In this case, although not shown, the second optical fibers 9a and 9b have the same configuration.

The light source 7 and the first optical fibers 8a, 8a
b, the optical path switching unit 17 is provided with the first optical fiber 8 disposed on the optical path of the light source 17 as shown in FIG.
a, and another first optical fiber 8b arranged at an angle of about 90 ° with respect to the optical path, and a detachable reflecting mirror 32 which is an optical path deflecting member with respect to the optical path. 32 is retracted to the position indicated by the broken line in FIG.
By moving the reflection mirror 32 on the optical path from the state where the optical fiber 8a of the first optical fiber 8a is located on the optical path of the light source 7, the other first optical fiber 8b
Is positioned on the optical path of the light source 7. In this case, although not shown, the optical path switching unit 18 disposed between the spectroscope 10 and the second optical fibers 9a and 9b has the same configuration.

Accordingly, with this configuration, the optical path switching unit 16 and the optical path switching units 17 and 18 can perform fiber switching only by the operation of the reflection mirrors 31 and 32 that can be inserted into and removed from the optical path. The configuration of each optical path switching unit can be simplified, and space saving of the device can be realized.

In the above-described embodiment, the spectroscope 1
Although 0 was used, if a photodetector capable of measuring the intensity of the wavelength at which the transmittance of the optical fiber decreases due to the deterioration of the optical fiber is used, the intensity of the wavelength at which the transmittance of the optical fiber decreases becomes less than a certain value. It is also possible to detect fiber degradation at the stage of the drop.

The spectroscope 10 is not limited to a monochromator,
A polychromator capable of simultaneously measuring from the ultraviolet region to the visible region may be used, or an interference filter transmitting 219 nm and an interference filter transmitting 350 nm by setting two optical paths may be provided.

The position of the reflecting mirror 13 of the optical section 14 may be between the condenser lens 12 and the observation window 6 of the etching chamber 1.

The light source 7 is not limited to the Xe lamp, but may be any light source capable of emitting light from the ultraviolet region to the visible region.
The reflecting mirror 13 is not limited to the Al coating, and may be a reflector such as a dielectric multilayer film that reflects a wavelength at which the transmittance decreases due to deterioration of the optical fiber and a wavelength at which the transmittance does not decrease even when the optical fiber deteriorates. Should be fine. Further, the wavelength for inspecting the deterioration of the optical fiber is 219 nm, 350 n
The wavelength is not limited to m, and may be any wavelength at which the transmittance decreases due to deterioration of the optical fiber and any wavelength at which the transmittance does not decrease even when the optical fiber deteriorates.

In the above description, the deterioration of the optical fiber due to the ultraviolet rays is detected. However, the breakage of the fiber is detected by the change in the transmittance of the optical fiber that guides light such as visible light that does not deteriorate the fiber. It is also possible to switch to a new optical fiber when the light intensity cannot be obtained due to the cutting of the optical fiber, etc., and to manufacture semiconductor devices such as defect inspection equipment using fiber illumination using a halogen lamp as a light source. Applicable to related equipment.

In the above description, the etching apparatus has been described. However, the present invention can be applied to any other manufacturing apparatus or defect inspection apparatus which is placed in an unmanned state or is continuously operated on a production line and uses an optical fiber.

[0055]

As described above, according to the present invention, it is possible to provide a fiber deterioration detecting apparatus which can efficiently detect deterioration of an optical fiber and realize quick fiber exchange.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a schematic configuration of an optical path switching unit used in the first embodiment.

FIG. 3 is a diagram illustrating a schematic configuration of a deterioration determination unit used in the first embodiment.

FIG. 4 is a diagram for explaining etching depth measurement in the first embodiment.

FIG. 5 is a diagram for explaining etching depth measurement in the first embodiment.

FIG. 6 is a diagram showing a schematic configuration of a second embodiment of the present invention.

FIG. 7 is a diagram showing a schematic configuration of a third embodiment of the present invention.

FIG. 8 is a diagram illustrating a schematic configuration of an optical path switching unit applied to a fourth embodiment of the present invention.

FIG. 9 is a diagram illustrating a schematic configuration of an optical path switching unit applied to a fourth embodiment;

FIG. 10 is a diagram showing a schematic configuration of a conventional etching apparatus.

FIG. 11 is a diagram for explaining detection of fiber deterioration in a conventional etching apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Etching chamber 2 ... Upper electrode 3 ... Lower electrode 4 ... High frequency power supply 5 ... Substrate to be etched 6 ... Observation window 7 ... Light source 8a. 8b 1st optical fiber 9a. 9b ... second optical fiber 10 ... spectroscope 11 ... calculating device 12 ... condensing lens 13 ... reflecting mirror 14 ... optical unit 16a ... slide member 16 ... slide member 17 ... light source 19 ... degradation detection unit 191 ... half mirror 192 ... Filter 193 First detector 194 Mirror 195 Filter 196 Second detector 197 Deterioration determination unit 21 Silicon substrate 22 U-shaped optical fiber 23 Deterioration detection unit 24 Light source 31 Reflector mirror 31.32 ... Reflection mirror 32 ... Reflection mirror

Claims (4)

[Claims] An optical fiber for guiding light; a fiber deterioration determining means for detecting the intensity of the light guided through the optical fiber to determine fiber deterioration; and a fiber deterioration determining means for the fiber deterioration determining means. A fiber switching means for switching an optical fiber on the optical path determined to be defective to a new optical fiber. 2. The fiber deterioration judging means according to claim 1, wherein said light guided through said optical fiber has a first wavelength at which the transmittance of said optical fiber does not decrease due to deterioration of said optical fiber and a second wavelength which degrades said optical fiber. The ratio I2 / I1 of the relative intensity I1 of the first wavelength and the relative intensity I2 obtained in the normal state when the second wavelength is normalized and normalized by the second wavelength becomes lower than the specified threshold. The fiber deterioration detection device according to claim 1, wherein the fiber deterioration is determined when the condition is detected. 3. The fiber switching means according to claim 2, wherein at least two optical fibers are arranged side by side, and a new optical fiber is positioned on the optical path by the fiber deterioration judgment by the fiber deterioration judgment means. Item 3. The fiber deterioration detection device according to item 1 or 2. 4. The optical fiber switching means includes an optical fiber disposed on an optical path and another optical fiber disposed at a predetermined angle with respect to the optical path, and an optical path deflection that can be inserted into and removed from the optical path. The fiber according to claim 1, further comprising a member, wherein the other optical fiber is positioned on an optical path via the optical path deflecting member by a fiber deterioration determination by the fiber deterioration determination unit. Deterioration detection device.