JPH0681151A - Cleaning method of window for container - Google Patents

Abstract

PURPOSE:To prevent the sticking of a reactional product to the transparent quartz window for a photochemical reaction vessel of a photo-CVD device, etc., and to easily remove and clean the once deposited reactional product by abrasion of a laser beam by irradiating the window with the laser beam. CONSTITUTION:The vapor of a raw material, Al(CH3)2H, is supplied from an inlet 3 of a vacuum vessel 1 and the laser beam 10 from an ArF excimer laser oscillator 9 is focused by a mirror 12 and a condenser lens 13 and is passed through a mask 15 to transfer the image of a mask 15 by an Al formed by decomposition of the Al(CH3)2H on the front surface 5a of the substrate 5 in the vessel 1 by the quartz window 2. The focus A of the laser beam 10 is formed on the quartz window 2 in order to prevent the impairment of transparency by sticking of a part of the Al of the inside of the vessel 1 and more particularly to the inner face of the quartz window 2 or to remove the Al once stuck to the inner face of the quartz window 2. The sticking of the Al is thus prevented or the stuck Al is completely cleared away by the abrasion effect of scanning with the laser beam by a reflection mirror 12.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for cleaning a window of a container by light. More specifically, by using high power density light including laser light, a container used in a vacuum vapor deposition device, a sputtering device, an electron beam melting device, a photo CVD device, a single crystal growth device containing a volatile substance, or an observation room of an electron microscope. The present invention relates to a window cleaning method for preventing contamination of the surface of a window provided on the window or cleaning the window when it is contaminated.

[0002]

2. Description of the Related Art Conventionally, a vacuum vapor deposition apparatus, a sputtering apparatus, an electron beam melting apparatus, an optical CVD apparatus which has been widely used in industrial equipment, facilities, machines, etc., and also in physicochemical research and testing equipment. The apparatus, the single crystal growth apparatus containing a volatile substance, the electron microscope, and the like are provided with a container or an observation chamber also called a jar or a chamber. These containers have a window for observing the inside of the container, or a light transmitting part for irradiating the internal reactant from the outside with light in order to cause a photochemical reaction inside the container like a photo CVD apparatus. Often windows are provided.

The window for observing the inside of the device is made of a material selected according to the type of object to be observed and the nature of the light used by the observing device. A normal glass is used as a window of an aluminum vacuum deposition apparatus, a lead glass is used as an electron microscope window, and a silica glass is used as an electron beam melting apparatus.

Silica glass or the like is used for a window for irradiating the reactant inside the container with light, for example, in a silicon photo-CVD apparatus.

[0005]

However, while these devices are in operation and use, foreign matter such as metal gradually deposits and adheres to the surface of the window and contaminates them, and the light transmittance decreases. If the light transmittance is drastically reduced, it becomes difficult to observe the inside of the container, or the reaction does not proceed due to insufficient light irradiation amount of the reactant inside the container, so that foreign substances on the surface of the window are regularly removed. It had to be removed to restore the light transmittance.

Contamination on the outside surface of the window can be easily cleaned, but the following method has been adopted for cleaning the surface facing the inside of the apparatus. For example, remove the window and replace or clean it with a clean one, attach a shutter inside the window and open it only during observation to reduce the adhesion of foreign matter, and attach it in an etching atmosphere or plasma etching state inside the container A method such as etching and removing the foreign matter is performed.

However, removing the window and replacing or cleaning it with a clean one must stop the device,
The operation rate of the equipment is reduced. Particularly in a vacuum device, it is necessary to return to atmospheric pressure once, and in the case of an ultra-high vacuum device, it may take a long time of several days to restore, and in an atmosphere device, there is a high possibility that impurities will be mixed into the container.

It is possible to reduce the speed of contamination, but it is not possible to completely prevent contamination by attaching a shutter to the inside of the window and opening it only during observation to reduce the adhesion of foreign matter. Moreover, the structure of the entire device becomes complicated,
In a vacuum device, it also causes a decrease in the degree of vacuum. It is difficult to employ it in an apparatus such as a photo-CVD apparatus which advances processing or work by irradiation of light.

When the inside of the container is made to have an etching atmosphere to remove the adhering foreign matter by etching, there is a problem that the inside of the container is contaminated by an etching substance, the quality of the workpiece is deteriorated and the degree of vacuum is deteriorated. Occur. The same applies to the method using plasma etching. The inconvenience caused by stopping the device is similar to the above-mentioned removal and cleaning.

It is an object of the present invention to provide a window cleaning method for preventing the surface of a window of a device from being contaminated or for easily cleaning the contaminated surface.

[0011]

According to the window cleaning method of the present invention, when a substance adheres to the surface of the window, the adhered substance is irradiated with high power density light to perform ablation, without damaging the window. It removes substances. Alternatively, the window is irradiated with high power density light to be ablated to prevent foreign matter from adhering and keep the window clean. And irradiation can be from either inside or outside the window.
And, one of the desirable irradiation method when attached to the inner surface of the window is a method of irradiating through the optical fiber from the inner side of the window, the irradiation light is preferably light using a laser as a light source, Of these, the excimer laser is preferable.

The phenomenon of ablation is a phenomenon caused by irradiating a solid surface with high power density light. The solid surface layer itself is decomposed by absorbing light, atoms and molecules are emitted, and when the light intensity further increases, ions and clusters of atoms are generated in addition to atoms and molecules.

High power density light is required to cause ablation, and a high density laser, especially an excimer laser, has a high light intensity and is therefore suitable. Then, an appropriate one is selected according to the physical properties such as the light intensity, the pulse width, the irradiation wavelength, the absorption wavelength and the absorption coefficient of the solid.

The light intensity is also referred to as the power density. Regarding this, in the example of irradiating an oxide superconductor with an ArF laser, ablation is recognized at a light intensity of about 50 mJ / cm ² per pulse or less. Ablation does not occur until the light intensity exceeds that. When the light intensity is further increased, in addition to the emission of atoms and molecules, the formation of clusters of ions and atoms comes to be recognized.

Further, the shorter the pulse width and the higher the peak value of energy, the more easily ablation occurs. Therefore, an excimer laser having a short pulse width of 1 to 50 ns or a pulse YAG laser with a Q-switch is suitable.

Regarding the irradiation wavelength, the shorter the wavelength, the more
Due to the large energy per photon, ultraviolet or excimer lasers with short wavelengths are often suitable.

Ablation does not occur unless the substance on the surface of the window to be irradiated absorbs light.

The container to which the present invention is particularly preferably applied is a container such as a vacuum vapor deposition apparatus, a sputtering apparatus, an electron beam melting apparatus, a photo CVD apparatus, a single crystal growth apparatus, an electron microscope, etc., but the entire surface is light transmissive. The present invention is also applicable to not only a closed container but also a transparent partition plate of the container.

The material of the window transmits the light required for observation or reaction, and is not limited to amorphous materials such as ordinary glass, lead glass, silica glass and chalcogen glass, but also quartz (SiO ₂ ), A crystalline material such as fluorite (CaF ₂ ) is also included, and the shape does not necessarily have to be a parallel plate.

[0020]

By irradiating light with a high power density, the surface of the window is kept clean by the ablation phenomenon, and when a substance adheres to the surface of the window, the substance is removed from the surface to clean the surface.

The silica glass used for the window is 180
It transmits light from nm to 3.5 μm, and fluorite crystals transmit light from 120 nm to 9 μm. When these windows are irradiated with excimer laser or YAG laser, they are not absorbed, so that the windows themselves are not ablated and are not damaged. However, if a substance such as a metal attached to the window has an absorption band in the ultraviolet or visible region, it absorbs light and ablation occurs. If the window material is normal soda lime glass, it can be replaced with silica glass so that the metal and other deposits inside the container are irradiated with light from the outside of the container, causing ablation. Can be made. When an atmosphere of fluorine gas that corrodes glass is used in the reaction system, it is preferable to use fluorine gas-resistant magnesium fluoride.

When the deposit on the window of the vacuum container is ablated, the particles divided into atoms and molecules jump out into the vacuum container and flow out to the vacuum pump side. At this time, if the pressure in the container is sufficiently low and is about 10 ⁻⁴ Torr, the particles fly in a linear trajectory and adhere to the wall surface of the container. If the apparatus is a sputtering apparatus, irradiation with laser light during film formation will only increase the deposition rate of the film and will not cause any problems. However, in the case of a photo-CVD apparatus, if laser light is irradiated during film formation, foreign matter may be mixed in the film to be deposited, and ablation during film formation is not appropriate.

When the pressure in the container is as high as several Torr, the produced particles collide with the gas molecules and flow out to the vacuum pump side, so that reattachment in the container is reduced.

Since the phenomenon of ablation itself is not so much influenced by the pressure inside the container, the pressure inside the container can be selected in consideration of the above phenomenon. Further, depending on the type of the apparatus used, whether the cleaning is performed when the container is used or after the container is stopped can be appropriately selected.

Irradiation of the laser beam to the window can be selected from the outside or the inside of the window. When irradiating from the outside of the window, light is guided from the laser irradiating device to the window according to a known conventional method. Ablation occurs inside the window provided that the window is not opaque to the laser light. If irradiation is performed after the transparency of the window is lost, ablation may occur near the interface between the window and the adhered substance and damage the window. Or you need to irradiate from inside the window. When the method of irradiating the laser from the outside of the window is adopted, it is not necessary to modify the conventional vacuum device itself.

When irradiating from the inside of the window, light is once guided into the container from a laser irradiation device provided outside the container,
After that, light is guided from the inside of the window. For example, it is advisable to introduce an optical fiber into the container, install it, and move it near the window when cleaning. When a large amount of deposits on the window is deposited, laser light is irradiated from the deposit side to ablate the deposited deposit surface.

Ablation occurs only by the energy of the absorbed light, and does not depend on the atmosphere or pressure. Therefore, no etching gas is required, and there is no contamination of the container by the etching gas. Further, what is generated by ablation is the deposit itself or a decomposition product thereof, and the total amount of deposit in the container does not increase.

Further, since the laser light is converged and irradiated on the window by a lens or the like, the light intensity is extremely high in the window at the converged position, but the light intensity sharply decreases at the position apart from the window, causing ablation. The effect of doing it will not appear. There is no adverse effect on the object to be processed or damage to the container.

[0029]

EXAMPLE A first example of light C of aluminum (Al)
A VD device will be described as an example with reference to FIGS. Figure 1
Is a conceptual diagram of the apparatus according to the first embodiment at the time of film formation, and FIG. 2 is a partial conceptual diagram at the time of cleaning. In this embodiment, Al (CH
₃ ) A method relating to an apparatus for decomposing ₂ H with an ArF laser to selectively and directly write aluminum on a semiconductor substrate.

In FIG. 1, a container 1 is a stainless steel tank, a quartz window 2 is provided at the upper opening, and a raw material gas inlet 3 and an exhaust outlet 4 are opened at the side surfaces. ing. The substrate 5 is a silicon wafer Si having a diameter of 2 inches, is placed on the susceptor 6, and is horizontally inserted into the container 1 by the stage 7. A shutter 8 is rotatably provided above the substrate 5 and below the quartz window 2 while being supported by a shaft 8a.

The laser oscillator 9 is an ArF excimer laser and emits deep ultraviolet rays having a wavelength of 193 nm in a pulsed manner. The emitted laser light 10 passes through the quartz window 2 as shown in FIG. , Or the quartz window 2 as shown in FIG.

The optical system 11 is provided with a mirror 12 for deflecting the direction of the laser beam 10. The mirror 12 is also a well-known beam scanner, and scans the laser light 10. The laser light 10 deflected by the mirror 12 is converged by the silica glass lens 13. The lens 13 is supported by the stage 14 and is movable in the vertical direction with respect to the quartz window 2. The laser beam 10 has a lens 13 and a quartz window 2 shown in FIG.
When it is close to the quartz window 2, it converges on the substrate 5, and when it is far from the quartz window 2 shown in FIG. 2, it converges on the quartz window 2.

A mask 15 for drawing is provided between the lens 13 and the quartz window 2 and can be moved interchangeably in the optical path as shown in FIG. 1 or in a position deviated from the optical path as shown in FIG. is there.

Next, using this apparatus, the photolysis of dimethyl aluminum hydride (Al (CH ₃ ) ₂ H) to draw aluminum on the substrate 5 will be described. Dimethylaluminum hydride vaporized by using argon gas (Ar) as a carrier gas is introduced as a source gas into the container 1 through the gas inlet 3 at a flow rate of 50 cc / min. Dimethyl aluminum hydride is
When ArF excimer laser light with a wavelength of 193 nm is irradiated at a predetermined intensity, it decomposes to produce aluminum, and the balance becomes various low-molecular molecules composed of carbon and hydrogen.

As shown in FIG. 1, the shutter 8 is opened, the laser oscillator 9 is turned on, the lens 13 is positioned near the quartz window 2, the mask 15 is positioned in the optical path,
The laser light 10 was arranged so as to be converged in the vicinity of the silicon substrate 5. The laser beam 10 was transmitted through the quartz window 2 and converged in the vicinity of the substrate 5 to decompose dimethylaluminum hydride in the vicinity of the surface 5a. The decomposed aluminum was transferred according to the image of the mask 15 and deposited on the surface 5a. The light intensity at this time is 5 per pulse.
It was 0 mJ / cm ² .

Regarding the convergence position of the light beam and the size of the spot, the light beam is converged at a high position A slightly apart from the surface 5a of the substrate 5, and the size of the spot on the substrate 5 is 5 × 5 to 10 ×. It was about 10 mm. By doing so, the strength becomes an appropriate size for the precipitation of aluminum, a film with good properties is obtained, and when the surface 5a is brought too close to the surface and converged, the strength becomes excessive, the precipitation rate decreases, and ablation occurs. Because it will be.

The gas produced by decomposition was discharged from the discharge port 4 together with the carrier gas as exhaust gas. The laser light transmitted through the quartz window 2 decomposes the dimethylaluminum hydride by the time it reaches the surface 5a of the substrate 5, but not all of it is deposited on the surface 5a, but a part of it is discharged together with the carrier gas as an exhaust port. 4 and the other part is deposited on the wall of the container 1 and the like. Part of what is deposited on the wall of the container 1 is deposited on the inner surface 2a of the quartz window 2 and is deposited as a contaminant 15.
Fogging of the windows became noticeable after hours of operation of the device.

Next, the removal of the contaminant 15 deposited and deposited on the inner surface 2a of the quartz window 2 will be described. As shown in FIG. 2, the shutter 8 is closed, the laser oscillator 9 is turned on, the lens 13 is moved far away from the quartz window 2, the mask 15 is moved away from the optical path, and the laser beam 10 is moved to quartz. They were arranged so as to converge on the window 2.

The energy of the laser beam 10 transmitted through the quartz window 2 and focused on the inner surface 2a is absorbed to cause ablation, and the contaminant 15 is removed. The intensity of the laser beam at this time was 1 J / cm ² per pulse.

The laser light 10 is reflected by the mirror 12 on the inner surface 2
The aluminum contaminant 15 spread in a plane was completely removed in 5 minutes by scanning XY at 5 mm / sec on a. However, the quartz window 2 itself does not absorb the light of the ArF excimer laser having a wavelength of 193 nm, does not cause ablation even if the intensity of the light is large, and is not worn.

The aluminum that had been separated by the ablation and was in the state of atoms or clusters was blocked by the shutter 8 in the closed state, and contamination of the susceptor 6 and other members inside the container 1 was not recognized. In this example, since the substrate is cleaned when the film formation is stopped, the substrate 5 is removed from the container 1, and therefore the substrate 5 is not contaminated by ablation.

Next, a second embodiment will be described with reference to FIG.
FIG. 3 is a conceptual diagram of the second embodiment. In this embodiment, gold (A
This relates to the sputtering device of u). Detailed description of the same or similar points as in the first embodiment will be omitted.

In FIG. 3, a quartz window 2 is provided on the side surface of the container 1.
The shutter 8 is provided inside the quartz window 2 so as to be closed during the sputtering process and open during observation. On the other side surface of the container 1, an Ar (argon) gas inlet 3 and an exhaust outlet 4 are opened. The substrate 16 is supported by a substrate holder 17 inserted from the upper side of the container 1, and the surface on which the film is formed faces downward. A gold target 18 is provided below the substrate 16 so as to face the surface on which the film is to be formed.

The laser oscillator 9 is a KrF excimer laser and radiates ultraviolet rays having a wavelength of 248 nm in a pulsed manner, and the radiated laser light 10 reaches the quartz window 2 via the optical system 11.

The optical system 11 is provided with a mirror 12 which is a reflecting mirror and a beam scanner, and deflects the direction of the laser beam 10 in two stages. The laser light 10 is converged by a lens 13 supported by a stage 14 for adjusting the convergence position.

Next, gold sputtering using this apparatus will be described. After a vacuum is drawn in advance by a turbo molecular pump (not shown), plasma is generated when Ar gas of 0.02 Torr is introduced and a high voltage is applied, and Ar ions in the plasma are placed on the cathode side of the target 1.
It collides with the gold on 8 and repels atomic gold, releasing it into a vacuum. The released gold atoms reached the substrate 16 placed facing the target 18 and were deposited to form a gold film.

Some of the gold atoms generated at this time are part of the substrate 1.
Other than 6 will fly and accumulate on the vessel wall. The quartz window 2 is blocked by the shutter 8 during the sputtering process,
Since gold atoms could not be completely shielded, gold was successively deposited on the quartz window 2 as a contaminant, and when the sputtering process was performed for 10 hours, the window became cloudy and observation became difficult.

Next, the removal of gold deposited and deposited on the quartz window 2 will be described. With the shutter 8 closed, the ultraviolet laser light 10 having a wavelength of 248 nm is focused on the quartz window 2. The energy density per pulse is set to 1 J / cm ² , and the beam size at this time is 2 mm × 2 mm.
When scanned at a scanning speed of 5 mm / sec,
The gold deposited on the quartz window 2 was ablated to reduce the film thickness, and was completely removed after about 10 minutes.

During this time, the quartz window 2 itself did not absorb light, did not cause ablation, and did not wear out.

The gold, which had been separated by ablation and was in the state of atoms or clusters, was not blocked by the shutter 8 in the closed state and did not contaminate the members in the container 1.

In this embodiment, the film can be cleaned even during film formation, and the operating rate of the device can be kept high.

Next, a third embodiment will be described with reference to FIG.
FIG. 4 is a conceptual diagram of the third embodiment. In this embodiment, gold (A
u) The window of the sputtering apparatus and the window of the tungsten (W) electron beam melting apparatus. Detailed description of the same or similar points to those of the first and second embodiments will be omitted.

In FIG. 4, a quartz window 2 is provided on the side surface of the container 1 of the sputtering apparatus, the surface of the substrate 16 on which the film is to be formed faces downward, and the gold target 18 is opposed to it.
Is provided.

A quartz window 22 is provided on the upper surface of the container 21 of the electron beam melting apparatus, and a shutter 28 is provided inside the quartz window 22 so as to be closed during the melting process and open during observation. A discharge port 24 connected to a vacuum pump (not shown) is opened on the side surface of the. Tungsten melt 2
5 is contained in a crucible 26 placed in a container 21, and an electron beam generated by an electron beam generator 27 impinges on the surface thereof and is heated.

The laser oscillator 9 is a KrF excimer laser, which radiates ultraviolet rays having a wavelength of 248 nm in pulses, and the radiated laser light 10 is split by a half mirror 29, and one light beam is a mirror 1 which is a reflecting mirror and a beam scanner.
The other light flux is converged on the quartz window 2 by the lens 13 via the mirror 2, and the other light flux is a mirror 30 which is a reflection mirror and a beam scanner.
It is converged on the quartz window 22 by the lens 31 via the.

In the sputtering apparatus, gold is 0.
Ar in plasma generated in Ar gas of 02 Torr
The ions were emitted as atoms and reached the substrate 16 to be deposited to form a gold film. At this time, some of the gold atoms generated were deposited on the quartz window 2 to cause fogging.

On the other hand, the gold deposited on the quartz window 2 was ablated by the laser beam 10 focused on the quartz window 2 and removed.

In the electron beam melting apparatus, the container 21
Is reduced to 1 × 10 ^-5 Torr, and the electron beam generator 27
When the tungsten melt 25 was irradiated with an electron beam generated from the tungsten melt 25, the tungsten melt 25 was heated and tungsten was evaporated and discharged from the discharge port 24. Deposited inside, making it difficult to observe the inside.

On the other hand, the tungsten deposited and deposited on the quartz window 22 was ablated and removed by the laser beam focused on the quartz window 22.

Thus, the windows of the two devices, the quartz window 2 and the quartz window 22, were individually irradiated with the laser light 10 emitted from one laser oscillator 9. However, the irradiation was performed simultaneously.
It is possible to prevent the substance from adhering to the surface of the window by ablation.

A fourth embodiment will be described with reference to FIG. 5 using an aluminum (Al) photo-CVD apparatus as an example. Figure 4 is the fourth
FIG. 6 is a conceptual diagram of the apparatus according to the embodiment of FIG. Detailed description of the same or similar points as in the first embodiment will be omitted. In FIG. 5, a quartz window 2 is provided above the container 1, and a substrate 5 is placed below the quartz window 2.

The laser oscillator 9a is an Ar laser, and the emitted laser beam 10a is deflected in direction by the mirror 12 of the optical system 11a and is converged by the lens 13 to form the quartz window 2
To reach the substrate 5. A mask 15 is provided in the optical path. The laser oscillator 9b is an ArF excimer laser, and the emitted laser light 10b is the optical fiber 31.
Then, it enters through the exit window 32 and converges on the quartz window 2.
The optical fiber 31 is swung by the magic hand 33, and the emission window 32 scans the entire surface of the quartz window 2.

Next, using this apparatus, the laser oscillator 9a
Lights up and dimethyl aluminum hydride (Al
When (CH ₃ ) ₂ H) is photolyzed to draw aluminum on the substrate 5, dimethylaluminum hydride is decomposed and aluminum is partially deposited on the inner side surface 2a of the quartz window 2 and the apparatus is operated for 2 hours. The cloudiness of the rear window became noticeable. Therefore, the laser oscillator 9b is turned on and the optical fiber 3
When No. 1 was swung by the magic hand 33 and the entire surface of the quartz window 2 was scanned by the exit window 32, the haze was removed and the transmittance was restored in 5 minutes.

Next, the laser oscillator 9a and the laser oscillator 9
When b was turned on and aluminum was drawn on the substrate 5, no fog was observed even after 5 hours of operation.

The fifth embodiment will be described with reference to FIG. 7 by taking an observation window of an electron microscope as an example. FIG. 7 is a conceptual diagram of the electron microscope of the fifth embodiment. Detailed description of the same or similar points as the above-described embodiments will be omitted. In FIG. 7, an electron gun 37 is provided above the lens barrel 36 of the electron microscope 35, and the electrons generated from the electron gun 37 are placed in the lens barrel 36 and the sample 3
The image of 9 is taken by the electron lens 38 and the fluorescent plate 4 in the projection chamber 40.
Image on 1. Then, this image is observed through the observation window 42.

The laser oscillator 9b is an ArF excimer laser, and the emitted laser light enters the optical fiber 31, is emitted from the emission window 32 and is converged on the observation window 42.

During the observation of the sample, stains due to the influence of scattered electrons were gradually accumulated on the observation window of the electron microscope, resulting in fogging. At this time, when the laser oscillator 9b was turned on, the optical fiber 31 was swung, and the observation window 42 was scanned, the fog was removed in 3 minutes.

As described in detail above, according to each embodiment, the window can be cleaned without contaminating the inside of the vacuum container with an etching agent or the like and without breaking the vacuum.
Further, since the vacuum container body can be cleaned without modification, the conventional vacuum device can be used as it is. As a result, in the industrial equipment such as the vacuum vapor deposition equipment and the electron beam melting equipment, the maintenance time of the equipment can be shortened and the deterioration of the quality due to the mixing of impurities can be prevented. Further, since the laser device or the like can be divided or moved to various places by an optical system or an optical fiber, one cleaning device can clean the light transmission windows of many vacuum devices separately or simultaneously.

The prevention of contamination by ablation according to the present invention, or the cleaning when contaminated, is mainly applied to a container of a vacuum apparatus, since light such as deep ultraviolet rays that cause ablation must not be absorbed by the atmosphere. .
However, needless to say, the present invention is not limited to the container of the vacuum device, and can be applied to a window in an atmosphere without light absorption.

Needless to say, not only excimer laser but also YAG laser can be used for the ablation according to the present invention.

[0071]

According to the method of the present invention, the window surface is kept clean by ablation by irradiation with high power density light, and when a substance adheres to the window surface, the substance is removed from the surface and the surface is cleaned. Therefore, observation is possible in the observation window, and irradiation is possible in the reaction irradiation window.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a first embodiment.

FIG. 2 is a partial conceptual diagram of the first embodiment during cleaning.

FIG. 3 is a conceptual diagram of a second embodiment.

FIG. 4 is a conceptual diagram of a third embodiment.

FIG. 5 is a conceptual diagram of a fourth embodiment.

FIG. 6 is a partial conceptual diagram of a fourth embodiment.

FIG. 7 is a partial conceptual diagram of a fifth embodiment.

[Explanation of symbols]

 1, 21 Container 2, 22 Quartz Window 3 Inlet 4, 4 Outlet 5 Substrate 6 Susceptor 7 Stage 8, 28 Shutter 9 Laser Oscillator 10 Laser Light 11 Optical System 12, 30 Mirror 13, 31 Lens 14 Stage 15 Mask 16 Substrate 17 Substrate Holder 18 Target 25 Melt 26 Crucible 27 Electron Beam Generator 29 Half Mirror 31 Optical Fiber 32 Ejection Window 33 Magic Hand 35 Electron Microscope 42 Observation Window

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Ogi 1-297 Kitabukuro-cho, Omiya City, Saitama Prefecture Central Research Laboratory, Mitsubishi Materials Corporation

Claims (5)

[Claims] 1. A method for cleaning a window of a container, which comprises irradiating a substance attached to a surface of a window of a container, which is transparent to light, with high power density light to remove the substance by ablation. 2. A method for cleaning a window of a container, which comprises irradiating the window with high power density light to prevent a substance from adhering to the surface of the window. 3. The method for cleaning a window of a container according to claim 1 or 2, wherein the high power density light is irradiated through an optical fiber. 4. The container window cleaning method according to claim 1, wherein the high power density light is light using a laser as a light source. 5. The method of cleaning a window of a container according to claim 6, wherein the laser is an excimer laser.