KR100822677B1 - Device for generating haze on photo mask - Google Patents

Abstract

An apparatus for generating haze on a photomask is provided to effectively analyze a correlation between generation of haze and the condition in a process chamber by intentionally controling the humidity, temperature and a gas composition ratio in the process chamber. An optical system processes a laser beam emitted form a laser emitting part in a manner that the laser beam has a predetermined shape and energy distribution. A window made of a light transmitting material that a laser beam transmits is installed in the upper part of a process chamber in which a space for disposing a photomask is installed wherein the space is isolated from the outside. While the laser beam transmitting the optical system transmits the window to be irradiated to the photomask disposed in the space, a monitoring part monitors whether haze is generated on the photomask. A moisture supply part supplies moisture to the space in the process chamber. A gas supply part supplies mixture gas to the space in the process chamber wherein at least one kind of gas is mixed in the mixture gas. A heating part increases the temperature of the space of the process chamber. An environment control part(60) respectively controls the moisture supply part, the gas supply part and the heating part in a manner that reference environment including reference humidity, reference temperature and a reference gas composition ratio is formed in the space based upon the humidity, the temperature and the gas composition ratio of the space.

Description

Device for generating haze on photo mask

1 is a schematic configuration diagram of a haze generating device of a photo mask according to a conventional example.

2 is a schematic configuration diagram of a haze generating device of a photo mask according to an embodiment of the present invention.

Figure 3 is a detailed view of the environmental control unit shown in FIG.

4 is a schematic block diagram of an environmental controller for controlling the environmental control unit shown in FIG.

FIG. 5 is a schematic block diagram illustrating a process of controlling the intensity of a laser beam radiated to the photo mask shown in FIG. 2.

<Description of the symbols for the main parts of the drawings>

10 ... laser emitter 20 ... attenuator

30 ... optical system 40 ... process chamber

41,42 ... Windows 43 ... humidity sensor

44 ... temperature sensor 45 ... gas sensor

49 Monitoring unit 50, 51 Energy measuring unit

60.Environmental control unit 61.Gas supply unit

62 Heating unit 63 Water supply unit

70 ... Environmental Control 71 ... Gas Control

72 ... temperature control 73 ... humidity control

81 Storage 82 Operation

83.Attenuator control unit 84.Calculation unit

85.Decision 86.Laser Emission Control

100.Haze generator of photo mask

501,511 ... beam splitter 511,512 ... energy meter

611 gas line 611a, 614a, 633a flow regulators

612 Mixing tank 613 Connecting line

621 Heating tank 622 Heater

631 ... Moisture Tank 632 ... Moisture Generator

633 ... moisture line

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a haze generating device for a photo mask, and more particularly, to a haze generating device for a photo mask for artificially forming a haze that is a growth defect on the surface of the photo mask to find a cause of haze generation.

In recent years, as the degree of integration of semiconductors increases, a light source that emits a laser beam having a wavelength of 200 nm or less is used in a photolithography process. For example, ArF excimer lasers that emit laser beams of 193 nm wavelength are widely used. However, when a laser beam having a wavelength of 200 nm or less is irradiated to the photomask, haze, which is a growth defect, is generated on the surface of the photomask, resulting in deterioration of the performance of the photomask and shortening of the photomask life. Therefore, in order to identify the cause of the haze generation and to study how to prevent the haze generation, there is an increasing need for a haze generating device that artificially generates haze in the photo mask.

1 illustrates a haze generating device 100 ′ of a photo mask according to a conventional example. Referring to FIG. 1, the haze generator 100 ′ includes a laser emitter 10 ′ that emits an excimer laser having a wavelength of 193 nm, an optical system that processes the laser beam so that the laser beam has a predetermined shape and energy distribution; And a process chamber 40 'in which the photomask 1 is disposed. The optical system includes a plurality of mirrors 31 ', 32', 33 ', a telescope 34' for processing the shape of the laser beam, and a homogenizer 35 'for uniformly processing the energy of the laser beam. And a focus lens 36 'for adjusting the focus of the laser beam and controlling the size of the laser beam. Upper and lower sides of the process chamber 40 'are provided with windows 41' and 42 'for transmitting the laser beam. Above and below the process chamber 40 ', there are provided beam splitters 501' and 511 'and energy meters 502' and 512 'for measuring the energy of the laser beam reflected by the beam splitter, respectively. In addition, a charge-coupled device camera 49 'is installed on the surface of the photomask to monitor whether or not a haze is generated on the surface of the process chamber 40'. In addition, the process chamber 40 'is connected to a gas supply part 45' for supplying gas and a humidity supply part 60 'for supplying humidity.

In addition, the pure energy of the laser beam irradiated to the photomask is determined by the energy of the laser beam measured by the upper energy meter 502 'and the transmittance of the beam splitter 501', which is irradiated to the photomask until the haze occurs. The accumulated energy of the laser beam is obtained by summing the pure energy of the laser beam which is irradiated until haze generation.

On the other hand, the variables affecting the haze generation are known as the amount of energy of the laser beam accumulated in the photomask until the haze generation and environmental conditions such as temperature and humidity inside the process chamber, so these variables should be controlled as desired by the researcher. do.

However, in the haze generator described above, the photomask cannot be irradiated with the laser beam of the energy intensity intended by the researcher until the haze is generated. That is, when the laser beam reacts with oxygen, the energy of the laser beam decreases, but conventionally, the energy until the pure energy of the laser beam and the haze is generated without considering the energy loss of the laser beam by oxygen in the process chamber. Since the stored energy of the beam is determined, an error occurs in the pure energy and stored energy of the laser beam.

Then, the laser beam having a constant energy intensity should be continuously irradiated to the photo mask 1 until the haze is generated. In the related art, the laser beam emitted from the laser emitter 10 'is processed in an optical system to process the chamber 40'. The energy intensity of the laser beam is not controlled so as to control the energy variation of the laser beam even if the energy of the laser beam incident on the photo mask is changed over time due to changes in the efficiency of the optical system. There was no way.

In addition, energy loss occurs in the laser beam depending on environmental factors inside the process chamber, for example, humidity, temperature, and gas composition inside the process chamber. Conventionally, the pure energy and the accumulated energy of the laser beam cannot be accurately determined without considering the environmental factors inside the process chamber. Furthermore, the environmental factors inside the process chamber 40 'could not be controlled as desired by the researcher until haze occurred.

When the laser beam is irradiated to the optical system, the windows 41 ', 42' and the beam splitters 501 ', 511' that are exposed to the air, the laser beam reacts with the optical system, the window, and the beam splitter, respectively. And the beam splitter is contaminated and the energy of the laser beam passing through the contaminated optics, window and beam splitter is reduced. Therefore, the pure energy and the accumulated energy of the laser beam cannot be measured accurately and furthermore, the energy intensity of the laser beam cannot be kept constant.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to irradiate a laser beam with a constant energy intensity to a photo mask until a haze occurs, and accurately measure the amount of energy of the laser beam accumulated in the photo mask. It is possible to provide a haze generating device for a photo mask which can be obtained and whose structure is improved to control the environment inside the process chamber.

In order to achieve the above object, the haze generating apparatus of the photomask according to the present invention comprises a laser emitting unit; An optical system for processing the laser beam such that the laser beam emitted from the laser emission unit has a predetermined shape and an energy distribution; A process chamber having a window made of a light-transmitting material through which the laser beam passes, and formed inside so that the space where the photo mask is disposed is isolated from the outside; A monitoring unit for observing whether or not haze has occurred in the photo mask while the laser beam passing through the optical system is radiated through the window and irradiated with the photo mask disposed in the space; A water supply unit supplying water to the space of the process chamber; A gas supply unit supplying a mixed gas of at least one gas mixed into a space of the process chamber; A heating unit for raising a temperature of the space of the process chamber; And the water supply unit, the gas supply unit, and the heating unit, respectively, to form a reference environment having a predetermined reference humidity, reference temperature, and reference gas composition ratio in the space of the process chamber based on the humidity, temperature, and gas composition ratio of the space of the process chamber. And a control unit for controlling.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a schematic configuration diagram of a haze generating device of a photo mask according to an embodiment of the present invention, FIG. 3 is a detailed view of the environmental control unit shown in FIG. 2, and FIG. 4 is an environmental control shown in FIG. 3. FIG. 5 is a schematic block diagram of an environment control unit for controlling a unit, and FIG. 5 is a schematic block diagram for describing a process of controlling the intensity of a laser beam irradiated on the photo mask shown in FIG.

2 to 5, the haze generating device 100 of the photomask of this embodiment includes a laser emitting unit 10, an attenuator 20, an optical system 30, a process chamber 40, The monitoring unit 49, the energy measuring units 50 and 51, the environmental control unit 60, and the environmental control unit 70 are provided.

The laser emitter 10 generates and emits a laser beam. The laser emission section 10 generates and emits a laser having a wavelength of 200 nm or less, for example, an excimer laser having a wavelength of 193 nm.

The attenuator 20 attenuates and adjusts the energy intensity of the laser beam emitted from the laser emitter 10. Energy intensity control of the laser beam is achieved by adjusting the angle of the attenuator 20.

The optical system 30 processes the laser beam so that the laser beam has a predetermined shape and energy distribution. The optical system 30 includes a mirror 31 for reflecting a laser beam, a telescope 32 for processing the shape of the laser beam, a homogenizer 33 for uniformly processing the energy of the laser beam, and a field lens ( field lens 34 and projection lens 35 for adjusting the focus of the laser beam. In the present embodiment, the laser beam of which energy intensity is adjusted in the attenuator 20 is incident to the optical system 30, processed, and then emitted toward the process chamber 40.

Inside the process chamber 40, a space is formed that is isolated from the outside. In the internal space of the process chamber 40, a stage (not shown) on which the photo mask 1 is mounted is installed. Windows 41 and 42 are provided above and below the process chamber 40, respectively. Each window 41, 42 is made of a light transmissive material, for example glass, through which a laser beam passes. Therefore, the laser beam processed by the optical system 30 passes through the upper window 41 and is irradiated to the photo mask 1.

In the process chamber 40, a humidity sensor 43 for measuring humidity inside the process chamber, a temperature sensor 44 for measuring temperature inside the process chamber, and a gas sensor 45 for measuring gas composition ratio inside the process chamber are provided. It is installed. In particular, the humidity sensor 43, the temperature sensor 44 and the gas sensor 45 is configured to be disposed around the photo mask 1, so that the environment in which the photo mask 1 is exposed during irradiation of the laser beam, that is, humidity, It is desirable to accurately measure the temperature and gas composition ratio.

In addition, the process chamber 40 is connected to a gas supplier 46 for supplying gas to the space of the process chamber. One side of the process chamber 40 is connected to a gas supply pipe 47 connected to the gas supplier 46, and the other side of the process chamber 40 is connected to a gas discharge pipe 48 through which gas in the process chamber is discharged. A valve 471 is installed in the gas supply pipe 47, and an auto pressure controller for controlling the volume of the exhaust gas to maintain a constant pressure in the space of the process chamber 40 in the gas discharge pipe 48. 481 is provided.

The monitoring unit 49 is installed above the process chamber 40. The monitoring unit 49 monitors whether haze is generated on the surface of the photo mask 1. In this embodiment, a charge-coupled device camera is used as the monitoring unit 49.

The energy measuring units 50 and 51 are provided above and below the process chamber 40, respectively. Each of the energy measuring units 50 and 51 includes beam splitters 501 and 511 and energy meters 502 and 512 which measure energy of the laser beam reflected from the beam splitter. An energy meter 502 disposed above the process chamber 40 measures the energy of the laser beam incident on the upper window 41, and an energy meter 512 disposed below the process chamber 40 measures the lower window 42. The energy of the laser beam emitted from is measured.

The attenuator 20, the optical system 30, and the upper beam splitter 501 are accommodated in the case 36, and the inlet port 361 and the outlet port 362 are formed in the case 36. When an inert gas, for example nitrogen gas, flows in through the inlet port 361 and out through the outlet port 362, the attenuator 20, the optical system 30, and the upper beam splitter 501 are each inert gas atmosphere. Since it is exposed to, the phenomenon that the attenuator 20, the optical system 30 and the upper beam splitter 501 by the laser beam can be prevented. Therefore, unlike the related art, it is possible to prevent a phenomenon in which energy of the laser beam is reduced. In addition, the lower beam splitter 511 is also housed in a separate case 513 in which the inlet port 514 and the outlet port 515 are formed. Therefore, when an inert gas, for example nitrogen gas, flows in through the inlet port 514 and flows out through the outlet port 515, the lower beam splitter 511 is exposed to the inert gas atmosphere, respectively, so that the lower beam splitter ( It is possible to prevent the phenomenon 511 is contaminated by the laser beam. In addition, a gas discharge part 11 for discharging an inert gas toward each of the windows 41 and 42 is provided in the vicinity of the upper window 41 and the lower window 42, respectively. It is possible to prevent contamination of the respective windows 41 and 42.

The environmental control unit 60 is for controlling the environment of the space of the process chamber 40, and includes a gas supply unit 61, a heating unit 62, and a water supply unit 63.

The gas supply unit 61 supplies a mixed gas in which one or more gases are mixed in the space of the process chamber to adjust the gas composition in the process chamber. The gas supply unit 61 has a plurality of gas lines 611 and a mixing tank 612. Different kinds of gases are supplied through each of the plurality of gas lines 611. Each gas line 611 is provided with a flow controller 611a for controlling the amount of gas, for example, a mass flow controller. Gas supplied to the gas line 611 is such as _{NH 3, O 2, N 2} , SO 2 is used. The mixing tank 612 is connected to each gas line 611, so that the gas supplied through each gas line 611 is mixed with each other in the mixing tank 612. The mixing tank 612 and the process chamber 40 are connected by a connection line 613. The mixed gas stored in the mixing tank 612 is supplied to the process chamber 40 through the connection line 613, and the amount of the mixed gas supplied is controlled by the flow regulator 613a installed in the connection line 613.

The heating part 62 is for raising the temperature of the space of the process chamber 40, and adjusts the temperature of the space of the process chamber 40 by heating the gas supplied from the gas supply part 61. The heating unit 62 includes a heating tank 621 and a heater 622. The heating tank 621 is installed on the connection line 613, so that the mixed gas supplied from the gas supply unit 61 flows into the heating tank 621. The heater 622 generates heat when the power is applied, and is provided on the outer surface of the heating tank 621. The mixed gas introduced into the heating tank 621 by the heat of the heater 622 is heated to flow into the process chamber 40 after the temperature of the mixed gas rises.

The water supply unit 63 is to supply water to the space of the process chamber, and supplies water to the mixed gas heated in the heating tank 621. The water supply unit 63 includes a water tank 631 and a water generator 632. As illustrated in FIG. 3, the water tank 631 is installed on the connection line 613 so that the mixed gas heated by the heater 622 flows into the water tank 631. The water generator 632 generates water and is connected to the water tank 631 through the water line 633. Water generated in the water generator 632 is introduced into the water tank 631 and mixed with the mixed gas. The water line 633 is provided with a flow controller 633a for controlling the amount of water.

The environment controller 70 allows a reference environment to be formed in the space of the process chamber. The reference environment consists of a preset reference humidity, reference temperature and reference gas composition ratio. The reference gas composition ratio means the ratio of each gas in the mixed gas in the process chamber. The environment controller 70 controls the gas supply unit 61, the heating unit 62, and the water supply unit 63 based on the humidity, the temperature, and the gas composition ratio of the space of the process chamber 40, respectively. The environmental control unit 70 includes a gas control unit 71, a temperature control unit 72, and a humidity control unit 73.

The gas controller 71 receives the gas composition ratio measured by the gas sensor 45 and controls the flow regulator 611a installed in each gas line 611. That is, the gas control unit 71 adjusts the composition of the mixed gas in the mixing tank by adjusting the amount of the specific gas flowing into the mixing tank 612. When the mixed gas is introduced into the process chamber 40 through the connection line 613 after the composition is adjusted as described above, the composition of the mixed gas in the process chamber 40 can be adjusted, so that the gas composition ratio in the process chamber is referred to as the reference gas composition ratio. Can be maintained. For example, when the concentration of nitrogen in the process chamber is to be increased or decreased, the flow rate regulator 611a installed in the gas line 611 to which nitrogen is supplied may be controlled to increase or decrease the amount of nitrogen supplied to the process chamber. The oxygen concentration causing the energy loss of the laser beam can also be appropriately controlled.

The temperature controller 72 receives the temperature measured by the temperature sensor 44 and controls the heater 622. That is, the temperature controller 72 controls the amount of heat generated by the heater 622 by increasing or decreasing the power applied to the heater 622, for example, a voltage, and thereby controlling the temperature of the mixed gas in the heating tank 621. As such, when the temperature of the mixed gas is adjusted and then flows into the process chamber 40, the temperature of the process chamber space is also increased and decreased, thereby maintaining the temperature of the process chamber space at the reference temperature.

The humidity controller 73 receives the humidity measured by the humidity sensor 43 and controls at least one of the flow regulator 633a and the moisture generator 632 installed in the moisture line 633. That is, the humidity controller 73 controls the moisture generator 632 to increase or decrease the amount of water generated by the water generator 632, and thus the amount of water supplied to the water tank 631 is increased or decreased. When the water flowing into the water tank 631 is supplied to the process chamber 40 together with the mixed gas, the humidity of the process chamber is increased and decreased, so that the humidity of the process chamber space can be maintained at the reference humidity. On the other hand, when the moisture generator 632 generates a certain amount of water, the humidity control unit 73 controls the flow controller 633a to adjust the amount of water supplied to the water tank 631, the humidity of the process chamber space You can also control. In addition, the humidity control unit 73 may control both the flow regulator 633a and the moisture generator 632 to control the humidity of the process chamber space.

In addition, the haze generating device 100 of the photomask of this embodiment further includes a storage unit 81, a calculation unit 82, and an attenuator control unit 83.

The storage unit 81 stores the energy loss ratio of the laser beam corresponding to each oxygen concentration. Here, the energy loss rate of the laser beam is a numerical value representing the degree of energy reduction of the laser beam when the laser beam reacts with oxygen and the energy of the laser beam decreases. The energy loss rate of the laser beam is preferably obtained empirically through experiments.

The calculating unit 82 receives the incident energy intensity of the laser beam measured by the energy meter 502 and the energy loss rate of the laser beam read out from the storage unit 81 and receives the pure energy of the laser beam irradiated to the photomask 1. Calculate the strength Here, the energy loss rate of the read laser beam is the energy loss rate of the laser beam corresponding to the oxygen concentration in the process chamber 40 measured by the gas sensor 45. In particular, in the present embodiment, the calculation unit 82 may determine the laser beam. Read the energy loss rate. And, the calculating unit 82 calculates the pure energy intensity of the laser beam by the following equation (1).

Where E _p is the pure energy intensity of the laser beam irradiated to the photomask 1, E ₁ is the incident energy intensity of the laser beam measured by the energy meter 502, and T ₁ is the intensity of the beam splitter 501. Is the transmittance, T ₂ is the transmittance of the upper window 41, and α is the energy loss rate of the calculated laser beam.

As described above, the calculation unit 82 calculates the pure energy of the laser beam by reflecting the energy reduction of the laser beam due to oxygen in the process chamber 40, thereby obtaining more accurate pure energy of the laser beam than in the related art. .

The attenuator control unit 83 controls the attenuator 20 based on the incident energy intensity of the laser beam measured by the energy meter 502. In particular, in this embodiment, the attenuator control unit 83 controls the attenuator 20 based on the calculated pure energy intensity of the laser beam. That is, the attenuator control unit 83 compares the pure energy intensity of the laser beam with a preset reference energy intensity and then adjusts the angle of the attenuator 20 appropriately so that the pure energy intensity of the laser beam is equal to the reference energy intensity. Control to terminate. Therefore, the laser beam of the reference energy intensity is irradiated to the photo mask 1 until the haze generation. And the accumulated energy of the laser beam irradiated to the photomask 1 until haze generation can also be known correctly.

The haze generating device 100 of the photomask of this embodiment further includes a calculation unit 84, a determination unit 85, and a laser emission unit control unit 86.

The calculator 84 receives the pure energy intensity of the laser beam calculated by the calculator 82 and calculates the cumulative energy intensity of the laser beam irradiated to the photomask 1 while the laser beam is irradiated. That is, the calculation unit 84 calculates the cumulative energy intensity of the laser beam in real time by cumulatively adding up the pure energy intensity of the laser beam over time.

The determination unit 85 receives the cumulative energy intensity of the laser beam calculated by the calculation unit 84, determines whether the cumulative energy intensity reaches a preset reference value, and outputs a determination signal when the cumulative energy intensity is equal to the reference value. . Here, the reference value is the cumulative energy of the laser beam irradiated to the photomask 1 until the haze is generated. In addition, the reference value may be changed by process conditions, for example, oxygen concentration, humidity, temperature, and pure energy intensity of the laser beam in the process chamber, and is obtained through experiments with various process conditions.

The laser emitter controller 86 receives the determination signal from the determiner 85 and controls the laser emitter 10. That is, the laser emitter controller 86 outputs a control signal for stopping the operation of the laser emitter 10 to the laser emitter 10. Therefore, the moment the haze occurs in the photo mask, the operation of the laser emitting section 10 is stopped so that the laser beam is not irradiated to the photo mask 1 any more.

As described above, in the present embodiment, since the humidity, temperature and gas composition ratio in the process chamber can be controlled as the researcher intended, it is possible to effectively analyze the correlation between haze generation and environmental conditions in the process chamber.

In addition, since the energy loss of the laser beam due to oxygen is reflected and the pure energy of the laser beam is calculated, the pure energy of the laser beam irradiated to the photomask and the accumulated energy of the laser beam irradiated to the photomask until haze is generated. You can get it correctly.

In addition, unlike the related art, by controlling the angle of the attenuator, the laser beam of the reference energy intensity can be continuously irradiated to the photomask until the haze occurs.

In addition, since the optical system, the window, the attenuator, and the beam splitter are configured to be exposed to an inert gas atmosphere, contamination of each of the optical system, the window, and the beam splitter by the laser beam can be prevented, thereby minimizing energy attenuation of the laser beam. Will be.

As mentioned above, the present invention has been described in detail with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications may be made by those skilled in the art within the technical idea of the present invention. It is obvious.

According to the present invention of the above configuration, it is possible to control the humidity, temperature and gas composition ratio of the space of the process chamber as desired.

In addition, it is possible to accurately obtain the pure energy intensity of the laser beam irradiated with the photomask and the accumulated energy of the laser beam irradiated with the photomask until the haze is generated.

Then, the laser beam of a constant energy intensity can be irradiated continuously to the photo mask.

Claims (8)

Laser emitters; An optical system for processing the laser beam such that the laser beam emitted from the laser emission unit has a predetermined shape and an energy distribution; A process chamber having a window made of a light-transmitting material through which the laser beam passes, and formed inside so that the space where the photo mask is disposed is isolated from the outside; A monitoring unit for observing whether or not haze has occurred in the photo mask while the laser beam passing through the optical system is radiated through the window and irradiated with the photo mask disposed in the space; A water supply unit supplying water to the space of the process chamber; A gas supply unit supplying a mixed gas of at least one gas mixed into a space of the process chamber; A heating unit for raising a temperature of the space of the process chamber; And The moisture supply unit, the gas supply unit, and the heating unit are respectively controlled to form a reference environment having a preset reference humidity, reference temperature, and reference gas composition ratio in the space of the process chamber based on the humidity, temperature, and gas composition ratio of the space of the process chamber. And a environmental control unit. The method of claim 1, In the periphery of the photo mask disposed in the space of the process chamber, a sensor for measuring the humidity, temperature and gas composition ratio of the space around the photo mask, respectively, and outputs the measured humidity, temperature and gas composition ratio to the controller, respectively. The haze generating apparatus of the photomask characterized by the above-mentioned. The method of claim 1, The gas supply unit may include a plurality of gas lines to which different kinds of gases are respectively supplied; And a mixing tank connected to each of the gas lines to mix the different kinds of gases and to be connected to the process chamber via a connection line through which the mixed gas flows. The heating unit includes a heating tank installed on the connection line and the mixed gas flows, and a heater that generates heat when power is applied to heat the heating tank. The water supply unit is provided on the connection line is provided with a water tank into which the mixed gas heated by the heating unit flows, and a water generator for supplying water to the water tank, Each gas line is provided with a flow regulator for controlling the amount of gas flowing into the mixing tank, The environmental control unit may include a gas control unit controlling each of the flow rate regulators such that the gas composition ratio in the process chamber is maintained at the reference gas composition ratio based on the gas composition ratio in the process chamber; A temperature control unit controlling the heater such that the temperature in the process chamber is maintained at the reference temperature based on the temperature in the process chamber; And a humidity controller configured to control the moisture generator to maintain the humidity in the process chamber at the reference humidity based on the humidity in the process chamber. The method of claim 1, An attenuator for controlling energy of the laser beam emitted from the laser emitter; And And an attenuator controller for controlling the attenuator to irradiate a laser beam having a predetermined reference energy to the photo mask based on the incident energy of the laser beam incident through the window of the process chamber. The mask is a haze generator. The method of claim 4, wherein A storage unit for storing an energy loss rate of the laser beam corresponding to each oxygen concentration; And And a calculating unit calculating a pure energy intensity of the laser beam irradiated to the photo mask based on the energy loss rate of the laser beam corresponding to the oxygen concentration in the process chamber read out from the storage unit and the incident energy of the laser beam. , And the attenuator control unit controls the attenuator so that the calculated pure energy of the laser beam is equal to the reference energy intensity. The method of claim 5, And a laser emitter controller configured to control the laser emitter so that the laser beam is not irradiated onto the photomask when haze occurs on the surface of the photomask based on the cumulative energy intensity of the laser beam irradiated to the photomask. The haze generator of the photomask. The method of claim 6, A calculator configured to calculate a cumulative energy intensity of the laser beam irradiated to the photomask based on the pure energy intensity of the laser beam while the laser beam is irradiated to the photomask; And And determining whether the cumulative energy intensity reaches a preset reference value and outputting an output signal to the laser emission controller if the cumulative energy intensity is equal to the reference value. Device. The method according to any one of claims 1 to 7, And the optical system and the window are each exposed to an inert gas atmosphere.

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