JPH09260303A - Semiconductor manufacturing equipment and cleaning thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for cleaning a semiconductor manufacturing equipment by which at least a chamber including a window can be cleaned without lowering a maintainability. SOLUTION: This is a method for cleaning a semiconductor manufacturing equipment which at least has a process chamber 3 for processing a semiconductor wafer 1 without allowing the wafer 1 to be brought into contact with the air, a source of laser 7 which emits laser 5 for heating the wafer 1, a window 11 for leading the laser 5 into the process chamber 3, and a gas lead-in system 17 for leading gas into the process chamber 3. Using the laser 5, a deposit layer which deposits to the window 11 is heated and then removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing apparatus having a chamber and a method of cleaning the chamber, and more particularly to removing deposits attached to the chamber.

[0002]

2. Description of the Related Art Recently, copper (Cu) has been used in place of aluminum (Al) as a conductive material for internal wiring layers of semiconductor devices.
Has been close up. This is because copper has a smaller specific resistance than aluminum and is suitable for fine wiring.

Further, conventionally, the internal wiring layer is generally formed by forming a conductive material layer on an interlayer insulating film and patterning the formed conductive material layer by a lithographic method.

However, as the internal wiring layers become finer and more multilayered, it becomes difficult to form them. Therefore, a method of forming a groove according to a wiring pattern in the interlayer insulating film itself and burying a conductive material in the groove to form an internal wiring layer is attracting attention.

In such a method, when copper is used as the conductive material, a step of melting the formed copper layer is added. This is because copper is surely embedded in the groove. In order to melt copper, energy is given to copper. A laser is used to energize the copper. The laser is
A copper layer formed on the wafer is irradiated with the gas from a process chamber that is isolated from the atmosphere and is introduced into the chamber through a window. The copper layer is heated and melted by being irradiated with the laser.

[0006]

By the way, the vapor pressure of copper is as high as about 6 × 10 ^-2 Pa in melting point. When one pulse of the laser irradiation is set to the melting point temperature × 100 nsec, it is about 0.
Copper with a thickness of 46 nm evaporates. When actually incorporating the process into the manufacturing line, it is considered that one pulse of laser irradiation should be (melting point temperature + 100 ° C.) × 100 ns. However, at this time, copper having a thickness of about 3.1 nm is evaporated. The evaporated copper adheres to the window.
If copper adheres to the window, the transmittance will decrease. If one lot is processed, the energy deposited on the wafer will definitely decrease due to the copper adhering to the window.

When copper is attached to the window and the energy applied to the wafer is reduced, the window is removed from the manufacturing apparatus and the window is cleaned to remove the attached copper.

However, there is a loss time such as a waiting time for cooling the manufacturing apparatus and a vacuum restart time, and maintainability is not good. The present invention has been made in view of the above circumstances, and an object thereof is to provide a cleaning method for a semiconductor manufacturing apparatus that can clean a chamber to which a window is attached without impairing maintainability. Another object of the present invention is to provide a semiconductor manufacturing apparatus that can efficiently perform the above cleaning method.

[0009]

In order to achieve the above object, according to the present invention, there is provided a process chamber for processing a semiconductor substrate in isolation from the atmosphere, an energy source for emitting energy for heating the substrate, and What is claimed is: 1. A method for cleaning a semiconductor manufacturing apparatus, comprising: a window that guides energy to the process chamber; and a gas introduction system that introduces gas into the process chamber, the deposit being attached to the window using the energy. Is heated to remove the deposits.

Further, a reactive gas that reacts with the deposit is introduced from the gas introduction system into the process chamber to make the atmosphere in the process chamber a reactive atmosphere in which the deposit undergoes a chemical reaction. It is characterized in that the deposit attached to the window is heated in an atmosphere to sublimate the deposit to remove the deposit.

Further, it is characterized in that the reactive atmosphere is replaced with a vapor phase etching atmosphere, and the reaction product produced in the reactive atmosphere is further removed by vapor phase etching.

Further, it is characterized in that at least the surface of the process chamber that has been exposed to the processing atmosphere is heated to remove the deposits adhering to the surface together with the deposits adhering to the window. There is.

Further, in order to achieve the above-mentioned other object, in the present invention, a process chamber for processing a semiconductor substrate in a state of being isolated from the atmosphere, an energy source for emitting energy for heating the substrate, and the energy It is characterized by including a window leading to the process chamber, a gas introduction system for introducing a gas into the process chamber, and a focus system for focusing the energy near the window.

Further, the focus system is characterized in that the energy is focused near the window before the energy reaches the window. Further, the focus system reflects the energy in the process chamber after the energy is guided to the process chamber through the window to focus the energy near the window. I am trying.

Further, the invention is characterized by further comprising a heating system for heating at least a surface of the process chamber exposed to the processing atmosphere. Further, the gas introduction system, in addition to the process gas for processing the substrate, a reactive gas that reacts with the deposits attached to the window,
It is characterized in that it is further introduced into the process chamber.

Further, a process chamber for processing a semiconductor substrate isolated from the atmosphere, an energy source for emitting energy for heating the substrate, a window for guiding the energy to the process chamber, and a gas for the process chamber. A method for cleaning a semiconductor manufacturing apparatus having at least a gas introduction system for introducing and a focus system for focusing the energy near the window, wherein the energy is focused near the window and adhered to the window. It is characterized in that the attached matter is heated to remove the attached matter.

Further, a reactive gas that reacts with the deposit is introduced from the gas introduction system into the process chamber to make the atmosphere in the process chamber a reactive atmosphere in which the deposit undergoes a chemical reaction, It is characterized in that the deposit attached to the window is heated in an atmosphere to sublimate the deposit to remove the deposit.

Further, it is characterized in that the reactive atmosphere is replaced with a vapor phase etching atmosphere, and the reaction product produced in the reactive atmosphere is further removed by vapor phase etching.

Further, at least the surface of the process chamber that has been exposed to the processing atmosphere is heated, and the deposits adhering to the surface are removed together with the deposits adhering to the window. There is.

Further, the energy is focused near the window before reaching the window. Further, the energy is guided to the process chamber through the window and then reflected in the process chamber to be focused near the window.

[0021]

Embodiments of the present invention will be described below. FIG. 1 is a sectional view of a semiconductor manufacturing apparatus (heat treatment apparatus) according to the first embodiment of the present invention.

As shown in FIG. 1, there is a process chamber 3 for processing a wafer 1 in isolation from the atmosphere. A laser source 7 that emits a laser 5 is provided outside the chamber 3. The laser 5 energizes the copper layer 9 formed on the wafer 1 to heat at least a portion of the copper layer 9. An example of the laser 5 is an excimer laser. The chamber 3 is made of a metal that does not allow laser light to pass through, and a glass window 11 that allows laser light to pass through is provided in a part of the chamber 3. The focus of the laser 5 is set by the optical system 13. The laser 5 is focused by the optical system 13 and guided into the chamber 3 through the window 11.

In the semiconductor manufacturing apparatus according to the first embodiment, the focus of the laser 5 is fixed. In order to focus the laser 5 on the copper layer 9, a Z-axis mechanism (not shown) that moves the wafer stage 27 in the Z-axis (vertical direction) is used. The member indicated by reference numeral 15 is a mirror for reflecting the laser 5 emitted from the laser source 7 and guiding the laser 5 to the optical system 13.

Further, a gas introduction system 17 and an exhaust system 19 are connected to the chamber 3 so that the pressure and atmosphere of the chamber 3 can be adjusted according to various heat treatment processes.

Further, a heater 21 is provided outside the chamber 3.
Is provided. The heater 21 is for heating at least the surface of the chamber 3 that is exposed to the processing atmosphere. The mounting position of the heater 21 is either inside the metallic housing 23 for forming the chamber 3 or outside the housing 23 as shown. The wafer 1 is mounted on the stage 27 supported by the support columns 25. The heater 21 is also provided in each of the support column 25 and the stage 27.

The heater 21 is further attached for the purpose of using it in the cleaning process described later. However, the heater 21 can be used during the heat treatment process, such as adjusting the temperature of the chamber 3, in particular, the temperature around the wafer 1 according to various heat treatment processes, in addition to the heating by the laser 5. .

The cross section shown in FIG. 1 is a cross section during the heat treatment step for melting the copper layer 9. To melt the copper layer 9, the laser 5 is focused on the copper layer 9. This gives energy to the copper layer 9,
The copper layer 9 is heated. The heated copper layer 9 becomes fluid. The fluidized copper flows into the step portion such as the wiring forming groove or the contact hole, and gradually fills the step portion.

At this time, copper evaporates from the heated copper layer 9. The evaporated copper adheres to the window 11 and the inner wall surface of the chamber 3 (the surface exposed to the processing atmosphere). FIG. 2 is a sectional view of the semiconductor manufacturing apparatus shown in FIG. The cross section shown in FIG. 2 is a cross section at the time of the cleaning process for removing the copper adhering to the window 11.

As shown in FIG. 2, an adhering substance layer 30 is formed on the window 11. The deposit layer 30 is formed by depositing evaporated copper. If the deposit layer 30 remains formed on the window 11,
Transmittance will be reduced. In order to remove the deposit layer 30, the semiconductor manufacturing apparatus according to the first embodiment irradiates the deposit layer 30 with the laser 5 to apply energy to the deposit layer 30 to heat the deposit layer 30. To do. By heating, the copper forming the deposit layer 30 evaporates from the deposit layer 30. As a result, the deposit layer 30 is removed.

In the first embodiment, the focus of the laser 5 is fixed, and the focus of the laser 5 is not aligned with the deposit layer 30. However, if the laser 5 hits,
Since energy is applied to the deposit layer 30, the deposit layer 30 can be heated. If such heating is continued, the deposit layer 30 can be evaporated and removed.

Further, the focus of the fixed laser 5 is near the stage 27, and there is a possibility that the stage 27 is thermally damaged during the cleaning of the window 11. To prevent this, in one form,
Stage 2 while cleaning window 11
7 is moved to a position where it is out of the focus of the laser 5. In another embodiment, the dummy wafer 100 is placed on the stage 27 as shown in FIG. Stage 27
By the dummy wafer 100 placed on the stage 2
7 is protected from thermal damage.

It is more preferable to heat the deposit layer 30 while using the exhaust system 19 to evacuate the chamber 3. This is because it is possible to prevent the copper evaporated from the deposit layer 30 from reattaching to the window.

Further, by keeping the chamber 3 degassed, the pressure in the chamber 3 can be kept low. If the pressure in the chamber 3 is lower than atmospheric pressure, for example, the vaporization point of copper is lowered, and vaporization of copper can be further promoted.

Further, in this first embodiment, in order to accelerate the vaporization / evaporation of the deposit layer 30, the atmosphere in the chamber 3 is an oxidizing atmosphere for oxidizing copper. The oxidizing atmosphere is created by introducing oxygen (O ₂ ) into the chamber 3 from the gas introduction system 17. Specifically, about 10 ⁻⁴ Pa is introduced as a partial pressure. This allows
The copper forming the deposit layer 30 is oxidized to Cu ₂ O. Cu ₂ O is easier to sublime than Cu. Temperature 60
The vapor pressure at 0 ° C is 10 ^-2 Pa. This allows
The vaporization / evaporation of the deposit layer 30 is further accelerated.

When copper is oxidized, Cu ₂ O is produced and at the same time CuO is produced. The vapor pressure of this CuO is lower than that of Cu ₂ O, and it is difficult to vaporize / evaporate. In order to quickly remove such CuO, it is advisable to replace the oxidizing atmosphere with a gas phase etching atmosphere. The gas phase etching atmosphere is changed from the gas introduction system 17 to the hydrofluoric acid vapor (H
It can be produced by introducing F vapor) and water vapor (H ₂ O vapor) into the chamber 3. As a result, CuO is vapor-phase etched and removed. If such vapor phase etching is performed at the end of the cleaning sequence, for example, the cleaning effect of the window 11 can be further enhanced.

Further, the laser 5 is used to heat the deposit layer 30, and the heater 21 is used to use at least the surface of the chamber 3 exposed to the processing atmosphere, that is, the inner wall of the housing 23 and the surface of the chamber support column 25. By heating the surface of the stage 27, the copper attached to this surface can be removed.

Next explained is a semiconductor manufacturing apparatus (heat treatment apparatus) according to the second embodiment of the invention. FIG.
4 is a cross-sectional view of the semiconductor manufacturing apparatus (heat treatment apparatus) according to the second embodiment of the present invention during a heat treatment step, FIG.
FIG. 6 is a sectional view of a semiconductor manufacturing apparatus (heat treatment apparatus) according to a second embodiment of the present invention during a cleaning step.

The manufacturing apparatus according to the second embodiment is the first
What is particularly different from the manufacturing apparatus according to the embodiment of
That is, the focus of the laser 5 is variable. By changing the focus of the laser 5, during the heat treatment process,
Focus the laser 5 on the process surface of the wafer 1,
During the cleaning process, the laser 5 can be focused on the deposit layer 30.

As shown in FIGS. 3 and 4, in the manufacturing apparatus according to the second embodiment, the focus of the laser 5 is changed by using the optical system 13. One example of realizing such an optical system 13 is to prepare two kinds of lenses having different focal points and replace them with each other in the heat treatment step and the cleaning step. Another example is to configure the optical system 13 with a zoom lens and change the focus between the heat treatment step and the cleaning step.

By thus focusing the laser 5 on the deposit layer 30, energy can be concentrated on the deposit layer 30 and the deposit layer 30 can be heated to a very high temperature. If the deposit layer 30 can be heated to a very high temperature, the vaporization / evaporation of the deposit layer 30
It can be promoted as compared with the manufacturing apparatus according to the first embodiment. Therefore, the cleaning method according to the present invention can be efficiently performed.

Further, in the manufacturing apparatus according to the second embodiment, since the focus of the laser 5 is focused on the adhering material layer 30 or in the vicinity thereof during the cleaning process, the thermal damage to the stage 27 is The number is smaller than that of the manufacturing apparatus according to the first embodiment. Therefore, in the cleaning process, a device for protecting the stage 27 from thermal damage is not always necessary.

Next explained is a semiconductor manufacturing apparatus (heat treatment apparatus) according to the third embodiment of the invention. FIG.
6 is a cross-sectional view of the semiconductor manufacturing apparatus (heat treatment apparatus) according to the third embodiment of the present invention during a heat treatment step, FIG.
[FIG. 6] is a sectional view of a semiconductor manufacturing apparatus (heat treatment apparatus) according to a third embodiment of the present invention during a cleaning step.

The manufacturing apparatus according to the third embodiment is the second
The focus of the laser 5 can be changed according to the manufacturing apparatus according to the embodiment. The manufacturing apparatus according to the third embodiment is particularly different from the manufacturing apparatus according to the second embodiment in how to change the focus of the laser 5.

As shown in FIGS. 5 and 6, in the manufacturing apparatus according to the third embodiment, the focus of the laser 5 is changed by using the reflector provided in the chamber 3. One example of realizing such a reflector is, in particular, as shown in FIG.
A mirror wafer 102 for reflecting the laser 5 is placed on the stage 27. And the mirror wafer 10
The stage 27 on which 2 is placed is moved in the vertical direction by the Z-axis mechanism 200 controlled by the Z-axis control device 300. The focus of the laser 5 reflected by the mirror wafer 102 changes according to the position of the stage 27 in the height direction. By utilizing this, the position of the stage 27 in the height direction may be adjusted so that the laser 5 is focused on the deposit layer 30.

Instead of the mirror wafer 102,
A reflector for reflecting the laser 5 may be provided separately from the stage 27. Also in the manufacturing apparatus according to the third embodiment, the laser 5 can be focused on the deposit layer 30, so that the same effect as the manufacturing apparatus according to the second embodiment can be obtained.

The manufacturing apparatus according to the third embodiment is the second
As compared with the manufacturing apparatus according to the embodiment, there is an advantage that the focus of the laser 5 set by the optical system 13 may be fixed.

On the other hand, in the manufacturing apparatus according to the second embodiment, compared with the manufacturing apparatus according to the third embodiment,
Since it is not necessary to transfer the mirror wafer 102 to the chamber 3, there is an advantage that the time and labor required for the cleaning process are not required.

As described above, according to the semiconductor manufacturing apparatus and the method for cleaning the semiconductor manufacturing apparatus described in the above-mentioned respective embodiments, the deposits adhered to the window 11 are vaporized / evaporated by heating with the laser 5, and the chamber is heated. Exhaust from 3. Thereby, the adhered matter adhering to the window 11 can be removed without removing the window 11 from the housing 23.

Considering the case where the semiconductor manufacturing apparatus and the cleaning method described in each of the above embodiments are incorporated in a manufacturing line, not only the maintainability but also the production efficiency of the manufacturing line can be improved. it can. That is, the entire manufacturing apparatus or the window 1
1 can be cleaned without removing it from the production line, and the time for which the production line is stopped is reduced.

Further, the cleaning method described in each of the above embodiments can be incorporated as one step in the laser melting step. For example, the cleaning process is performed after the laser melting process for one lot is completed. Then, after the cleaning process is completed, the laser melting process for the next lot is started, and so on.

In this way, the cleaning process is
It will be one of the manufacturing process sequences, and further improvement in production efficiency can be expected. In addition, it is possible to obtain a semiconductor manufacturing apparatus that is substantially maintenance-free with respect to the removal of deposits.

Further, the atmosphere in the chamber 3 is set to a reactive atmosphere in which the attached matter causes a chemical reaction, and particularly, a reactive atmosphere in which the attached matter causes a chemical reaction for converting into a substance having a higher vapor pressure. Then, vaporization / evaporation of the deposit can be further promoted.

A more specific example is as described above,
When the deposit is copper, the atmosphere in the chamber 3 is an oxidizing atmosphere. As a result, copper is converted into Cu ₂ O having a higher vapor pressure.

When the deposit is, for example, copper, the atmosphere in the chamber 3 may be a fluorinated atmosphere or a chlorinated atmosphere in addition to the oxidizing atmosphere. Furthermore, during conversion of the deposit into a substance having a higher vapor pressure in the reactive atmosphere, a reaction product having a lower vapor pressure may be simultaneously produced. At this time, adding a step of replacing the reactive atmosphere with a gas phase etching atmosphere and further removing the above reactive products by gas phase etching is useful for shortening the cleaning time and improving the cleaning accuracy.

A more specific example is when copper is being converted to Cu ₂ O. At this time, a substance such as CuO that is not easily vaporized may be simultaneously generated. By replacing this CuO with a gas phase etching atmosphere, gas phase etching is performed. This allows CuO to be removed faster than it can be vaporized / evaporated.

An example of the vapor phase etching atmosphere is a mixed atmosphere of hydrofluoric acid vapor (HF vapor) and water vapor (H ₂ O vapor). Regarding the vapor phase etching atmosphere, depending on the reaction product, It can be changed in various ways.

Furthermore, by heating at least the surface of the chamber 3 that has been exposed to the processing atmosphere, it is possible to remove the deposits adhering to this surface together with the deposits adhering to the window. is there.

A more specific example is as described above,
The laser 5 is used to heat the deposit layer 30 and the heater 21 is used to expose at least the surface of the chamber 3 to the processing atmosphere, that is, the inner wall of the housing 23, the surface of the chamber support column 25, and the surface of the stage 27. Etc. may be heated at the same time. This makes it possible to remove not only the deposit attached to the window 11 but also the deposit attached to the surface of the chamber 3 that was exposed to the processing atmosphere.

In each of the above embodiments, an example in which copper adheres to the window 11 has been described, but the deposits that can be removed using the present invention are not limited to copper. For example, even when aluminum or the like is attached, it can be removed by utilizing the present invention.

[0060]

As described above, according to the present invention, there is provided a semiconductor manufacturing apparatus cleaning method capable of cleaning the chamber to which the window is attached without impairing maintainability, and a semiconductor method capable of efficiently performing the cleaning method. Manufacturing equipment can be provided respectively.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a semiconductor manufacturing apparatus according to a first embodiment of the present invention during a heat treatment process.

FIG. 2 is a sectional view of the semiconductor manufacturing apparatus according to the first embodiment of the present invention during a cleaning step.

FIG. 3 is a sectional view of the semiconductor manufacturing apparatus according to the second embodiment of the present invention during a heat treatment step.

FIG. 4 is a sectional view of a semiconductor manufacturing apparatus according to a second embodiment of the present invention during a cleaning step.

FIG. 5 is a sectional view of a semiconductor manufacturing apparatus according to a third embodiment of the present invention during a heat treatment step.

FIG. 6 is a sectional view of a semiconductor manufacturing apparatus according to a third embodiment of the present invention during a cleaning step.

[Explanation of symbols]

1 ... Wafer, 3 ... Chamber, 5 ... Laser light, 7 ... Laser light source, 9 ... Copper layer, 11 ... Window, 13 ... Focus system, 15 ... Mirror, 17 ... Gas introduction system, 19 ... Exhaust system, 21 ... Heater, 23 ... housing, 25 ... support pillar,
27 ... Stage, 30 ... Adhesion layer (copper).

Claims (15)

[Claims] 1. A process chamber for processing a semiconductor substrate in isolation from the atmosphere, an energy source for emitting energy to heat the substrate, a window for directing the energy to the process chamber, and a gas for the process chamber. A method of cleaning a semiconductor manufacturing apparatus having at least a gas introduction system for introducing gas, wherein the energy is used to heat the deposit attached to the window to remove the deposit. Cleaning method for manufacturing equipment. 2. A reactive gas that reacts with the deposit is introduced from the gas introduction system into the process chamber to make the atmosphere in the process chamber a reactive atmosphere in which the deposit causes a chemical reaction. The deposit attached to the window is heated in an atmosphere to sublimate the deposit to remove the deposit.
A method for cleaning a semiconductor manufacturing apparatus according to item 1. 3. The method according to claim 2, wherein the reactive atmosphere is replaced with a gas phase etching atmosphere, and a reaction product generated in the reactive atmosphere is further removed by gas phase etching. Cleaning method for semiconductor manufacturing equipment. 4. A method of heating at least a surface of the process chamber, which has been exposed to a processing atmosphere, to remove deposits adhering to the surface together with deposits adhering to the window. Claim 1 to Claim 3
The method for cleaning a semiconductor manufacturing apparatus according to claim 1. 5. A process chamber for processing a semiconductor substrate in isolation from the atmosphere, an energy source for emitting energy for heating the substrate, a window for guiding the energy to the process chamber, and a gas for the process chamber. A semiconductor manufacturing apparatus comprising: a gas introduction system for introducing the gas; and a focus system for focusing the energy near the window. 6. The semiconductor manufacturing apparatus according to claim 5, wherein the focus system focuses the energy near the window before the energy reaches the window. 7. The focus system reflects the energy in the process chamber after the energy has been guided to the process chamber through the window to focus the energy near the window. The semiconductor manufacturing apparatus according to claim 5, wherein: 8. The semiconductor manufacturing apparatus according to claim 5, further comprising a heating system for heating at least a surface of the process chamber exposed to a processing atmosphere. 9. The gas introduction system further introduces, into the process chamber, a process gas for treating the substrate and a reactive gas that reacts with the deposits attached to the window. The semiconductor manufacturing apparatus according to any one of claims 5 to 8. 10. A process chamber for processing a semiconductor substrate in isolation from the atmosphere, an energy source for emitting energy to heat the substrate, a window for directing the energy to the process chamber, and a gas for the process chamber. A method of cleaning a semiconductor manufacturing apparatus having at least a gas introduction system for introducing and a focus system for focusing the energy near the window, wherein the energy is focused near the window and adhered to the window. A method for cleaning a semiconductor manufacturing apparatus, which comprises heating an attached substance to remove the attached substance. 11. A reactive gas that reacts with the deposit is introduced from the gas introduction system into the process chamber to make the atmosphere in the process chamber a reactive atmosphere in which the deposit undergoes a chemical reaction, 11. The method for cleaning a semiconductor manufacturing apparatus according to claim 10, wherein the deposit attached to the window is heated in an atmosphere to sublimate the deposit to remove the deposit. 12. The method according to claim 11, wherein the reactive atmosphere is replaced with a gas phase etching atmosphere, and a reaction product generated in the reactive atmosphere is further removed by gas phase etching. Cleaning method for semiconductor manufacturing equipment. 13. A method of heating at least a surface of the process chamber, which has been exposed to a processing atmosphere, to remove deposits adhering to the surface together with deposits adhering to the window. 13. The method for cleaning a semiconductor manufacturing apparatus according to claim 10, wherein the cleaning method is used. 14. The method for cleaning a semiconductor manufacturing apparatus according to claim 10, wherein the energy is focused near the window before reaching the window. 15. The energy is directed into the process chamber through the window and then reflected in the process chamber to be focused near the window. Item 14. A method for cleaning a semiconductor manufacturing apparatus according to any one of items 10 to 13.