JP3472052B2 - Projection exposure equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus, and is particularly suitable for manufacturing semiconductor ICs and LSIs.

[0002]

2. Description of the Related Art The progress of semiconductor technology has been increasing more and more in recent years, and the progress of fine processing technology has been remarkable accordingly. In particular, the optical processing technology that forms the core of this technology has advanced into processing in the sub-micron region, with 1 MDRAM as the boundary. The method that has been used so far as a means for improving the resolution in optical processing has been to fix the exposure wavelength and increase the NA of the optical system. Recently, however, attempts have been made to expand the limits of the optical exposure method by using a projection exposure apparatus that shortens the exposure wavelength from g-line to i-line, and further using excimer lasers to exposure wavelengths of 248 nm and 193 nm.

FIG. 8 is a schematic view of a main part of a light source and an illumination optical system of a conventional projection exposure apparatus. In the figure, 71
Is a light source and is composed of a mercury lamp. The light emitting point of the light source 71 is arranged at the first focal point 72a of the elliptical mirror 72. On the inner surface of the elliptical mirror 72, various dielectric materials are vapor-deposited in multiple layers to form a reflecting surface that gives the maximum reflectance at the wavelength of the exposure light. Reference numerals 73 and 77 are bending mirrors, and like the elliptical mirror 72, various dielectric materials are vapor-deposited in multiple layers on the reflecting surface to form the reflecting surface. 74 is a collimator lens, 75 is a bandpass filter that passes only the necessary wavelengths,
76 is a fly-eye lens that forms a large number of secondary light sources, 78 is a condenser lens, and 79 is a reticle.

The operation of this portion will be described. The light emitted from the light source 71 is reflected by the elliptical mirror 72 and the bending mirror 73 and focused on the second focal point 72b of the elliptic mirror 72, where a light source image is formed. The divergent light from the light source image is converted into parallel light by the collimator lens 74, enters the bandpass filter 75, becomes illumination light of a required wavelength, and enters the fly-eye lens 76.

The focal plane of the fly-eye lens 76 has a large number of 2
A secondary light source is formed. The divergent light from many secondary sources is
The light enters the condenser lens 78 through the bending mirror 77 and illuminates the pattern surface of the reticle 79. The pattern of the reticle 79 is imaged on a wafer (photosensitive object) (not shown) via a projection lens (not shown).

FIG. 9 is a schematic view of a main part of a conventional projection exposure apparatus using an excimer laser as a light source. The projection exposure apparatus photoelectrically detects the alignment mark of the reticle and the alignment mark of the wafer to adjust the position of the wafer for alignment, and then illuminates the pattern on the reticle with the illumination light from the excimer laser. Is exposed on the wafer by.

As a method of alignment, a method of performing alignment using light having a wavelength different from that of the excimer laser,
Alternatively, a method is known in which an excimer laser is also used as a light source for alignment and alignment is performed in synchronization with a pulse wave from the excimer laser.

In the method of performing alignment using light having a wavelength different from that of the excimer laser, since the exposure wavelength and the alignment wavelength are different, even if the chromatic aberration of the projection lens is corrected, the distortion map is different for two wavelengths. However, there is a problem that an alignment offset based on the lens distortion is required, and the alignment accuracy is lowered.

The projection exposure apparatus of FIG. 9 solves the above problems by performing projection exposure and alignment using excimer laser light. In the figure, 1 is a light source, which is composed of an excimer laser. 2 is a diverging lens, 3, 5 and 8 are lenses, and 9 and 11 are mirrors. 10 is a fly-eye lens that forms a large number of secondary light sources. 12 is a condenser lens and 13 is a reticle, and a pattern to be projected and printed is formed on one surface thereof. Reference numeral 13a is a positioning mark provided on the reticle 13. 14 is a projection lens. Reference numeral 15 is a stage for moving the wafer 19. Reference numeral 16 is an interferometer that detects the amount of movement of the stage 15, and 17 is a drive device that drives the stage 15. Reference numeral 18 is an alignment reference mark provided on the stage 15, and 19a is an alignment mark on the wafer 19.

Divergence lens 2, lenses 3, 5, 8 and mirrors 4, 9,
11, the fly-eye lens 10, the condenser lens 12, etc. constitute one element of the illumination optical system, and the light source 1, the illumination optical system, the reticle 13, the projection lens 14, etc. constitute one element of the projection optical system. .

Reference numeral 21 is a condenser lens, 22a to 22f are lenses, and 33,3
4 is a mirror, 25 is a half mirror, 26 is an objective lens, 27 is a mirror, and 28 is a lens. Reference numeral 29 is a camera that captures an alignment image, and 30 is a processing device that calculates the amount of misalignment of the alignment mark.

The condenser lens 21, the mirrors 33 and 34, the half mirror 25, the objective lens 26, the mirror 27, the lens 28, the camera 29 and the like constitute one element of the alignment optical system.

Reference numeral 6 denotes a mirror, which is driven by a driving device 7 and switches the light from the laser to the alignment optical system side when it moves into the illumination optical path. Reference numeral 20 denotes a control device that controls the light source 1, each drive device, the interferometer 16, the processing device 30, and the like.

The operation of the conventional example will be described. First, the operation of the projection optical system will be described. The pulsed light from the excimer laser 1 whose lighting is controlled by the controller 20 is divergent lens.
It is expanded to an appropriate size by 2 and guided to the fly-eye lens 10 through the lens 3, the mirror 4, the lenses 5 and 8 and the mirror 9. Uniform illumination light generated by many secondary light sources formed by the fly-eye lens 10 illuminates a pattern on the reticle 13 via the mirror 11 and the condenser lens 12.

The pattern on the reticle 13 is the projection lens 14
Projected onto the wafer 19. The controller 20 monitors the position of the stage 15 with the interferometer 16 and sends a control signal to the driver 17 to drive the stage 15.

The stage 15 is driven so as to repeat step and repeat. Excimer laser 1 is the stage
It is controlled to emit light in synchronization with the driving of 15. By the above operation, the pattern of the reticle 13 is sequentially printed on the wafer 19.

Prior to the baking, alignment for positioning the wafer 19 at the correct position is performed, which will be described below. The alignment optical system includes alignment marks 13a for the reticle 13, alignment marks 19a on the wafer 19,
Alignment is performed using the alignment reference mark 18 of the stage 15.

Light for alignment is taken out by the mirror 6. The control device 20 drives the drive device 7 to drive the mirror 6
Is moved into the optical path of the illumination optical system to switch the optical path of the light from the light source 1 from the fly-eye lens 10 side to the alignment optical system side.

As a result, the light is reflected by the mirror 6, and through the lenses 22a to 22d, the mirror 33, the lens 22e, the mirror 34, the lens 22f, the half mirror 25, the objective lens 26 and the mirror 27, the alignment mark 13a is formed. Illuminate. The light illuminating the alignment mark 13a is further projected by the projection lens 14 onto the alignment mark 19a on the wafer and the stage 15
Illuminate the reference mark 18 for position alignment.

The return light from each mark returns through the projection lens 14, the mirror 27, and the objective lens 26 to the half mirror 25, where it is reflected and focused by the lens 28 on the image pickup surface of the camera 29.

The image signal from the camera 29 is arithmetically processed by the processing device 30 to calculate the positional deviation amount of each mark. The result is sent to the control device 20, which feeds the displacement amount to the drive device 17,
Correct the position shift amount of 19. The above is the description of the alignment operation.

This projection exposure apparatus includes a reticle 13 and a wafer 19
After the alignment is performed, the mirror 6 is retracted from the optical path of the light, the reticle 13 is illuminated by the illumination light, the pattern on the reticle 13 is reduced by the projection lens 14 and projected onto the wafer 19 for exposure.

[0023]

When the light source and the illumination optical system of the conventional projection exposure apparatus shown in FIG. 8 are used while being open to the outside air in the clean room, an elliptical mirror is used.
It is known that white powder adheres to the surfaces of the incidence surfaces of 72, the bending mirror 73, the collimator lens 74, and the bandpass filter 75. This powder has been found to be ammonium sulfate. Due to the above-mentioned phenomenon, the optical component becomes clouded, its reflectance or transmittance is lowered, and the illumination efficiency is lowered.

A technique for solving this problem is disclosed in Japanese Patent Laid-Open No. 4-128702. In this publication, the fact that the decomposition of ammonium sulfate starts at about 120 ° C. is used, and the adhesion of the powder is prevented by keeping the optical components at 120 ° C. or higher.

However, if it is attempted to maintain the optical parts at a high temperature of 120 ° C. or higher, the optical parts arranged near the light source part and the light collecting part can be implemented relatively easily, but the other optical parts are Must be heated and optics 1
Heating to 20 ° C or higher requires a considerably large heat source, which is a problem in a projection exposure apparatus that requires strict temperature control.

Furthermore, in the conventional projection exposure apparatus of FIG. 9, an excimer laser is used as a light source for alignment. As disclosed in the above publication, in a device using an excimer laser as a light source, fog is likely to occur in an optical component, and there arises a problem that reflectance or transmittance of the optical component is reduced and illumination efficiency is reduced. To do. Although the above publications mainly describe the illumination optical system, when the light from the excimer laser is introduced into the alignment optical system for alignment, a similar problem occurs in the optical element, The alignment accuracy will be reduced.

At this time, if the optical components are kept at a high temperature in the alignment optical system to prevent fogging, the characteristics will change due to the deformation of the optical components and structural components due to temperature changes, and the positional deviation detection accuracy itself will be high. The problem of diminishing occurs.

Another technique for preventing fogging is disclosed in JP-A-6-202243. In this publication, attention is paid to the fact that sulfur dioxide has four absorption bands depending on the first excited state to the fourth excited state, and the reflectance of the reflection condensing member for light in the absorption band is reduced. By reducing the reflectance of the reflection condensing part, the irradiation amount of light that activates sulfur dioxide decreases,
This reduces the amount of ammonium sulfate produced.

However, even if the reflectance of the reflecting and condensing member with respect to the light in the absorption band is decreased, the amount of ammonium sulfate produced is reduced, but the production is not completely eliminated, so that the problem of lowering the illumination efficiency is still present. Remaining.

It is also known to replace the atmosphere of the portion where it is desired to prevent the reduction of the illumination efficiency with clean nitrogen to prevent fogging. In order to reduce the running cost of the excimer laser of the conventional projection exposure apparatus shown in FIG. 9, it is desirable to install the light emitting part (laser body) outside the clean room. However, in this case, all the light guide parts of the excimer laser light from the excimer laser emission part to the illumination optical system are sealed in the container and the inside is replaced with nitrogen, so that the volume of the container becomes large and very large. This requires a large amount of nitrogen, which increases running costs and poses a problem. Further, if the volume of the portion replaced with nitrogen is large, the cost of the projection exposure apparatus itself will increase.

In particular, the light guide section from the light emitting section of the excimer laser of the conventional projection exposure apparatus to the illumination optical system has a structure whose optical axis can be adjusted when the excimer laser is installed, and
As described above, the structure must be hermetically sealed or substantially hermetically sealed, resulting in a complicated structure, which is a problem in terms of space and cost.

Further, in order to prevent a decrease in illumination efficiency, it is necessary to replace nitrogen with nitrogen before operating the exposure apparatus. However, as the area replaced with nitrogen increases, the exposure apparatus startup time (until replacement) However, there is a problem that the waiting time) becomes longer.

Further, in order to prevent the deterioration of the illumination efficiency and improve the operating rate and reliability of the exposure apparatus, it is necessary to completely maintain the state of substitution with nitrogen. For that purpose, it becomes necessary to monitor the replacement state, and the exposure apparatus becomes larger and larger, and the cost also increases.

Further, in the conventional projection exposure apparatus of FIG. 9, mirrors 33 and 34 are used for guiding light to the alignment optical system. Therefore, in order to prevent fogging of the optical element of the alignment optical system including this portion, the condenser lens 21
To seal the optical path including the mirrors 33 and 34 with a container, or
Since it is necessary to have a substantially sealed structure and replace with nitrogen, this container has a large volume.

Further, at that time, since the volume of the hermetically sealed portion is large, the area of the hermetically sealed portion also becomes large, and the possibility of nitrogen leakage increases, which also increases the consumption of nitrogen.

Further, in the conventional example, it is necessary to replace the space, that is, the space between the condenser lens 21 and the mirror 34, with a container, or with a substantially sealed structure and expandable structure, and replace with nitrogen. When light is guided to the alignment optical system, if the whole or a part of the alignment optical system has a moving mechanism, the mechanism becomes more complicated. That is, it is necessary to make a structure capable of expanding and contracting by a moving mechanism between an entrance portion for guiding light and a portion hermetically or substantially hermetically sealed by a container, which causes a problem in terms of space and cost.

According to the present invention, the main optical elements of the light source, the illumination optical system and / or the alignment optical system are used in a nitrogen atmosphere to prevent deterioration of illumination efficiency and alignment accuracy due to clouding of the optical elements and to achieve high resolution. It is an object of the present invention to provide a projection exposure apparatus that realizes the above, reduces the nitrogen consumption at that time, and reduces the running cost of equipment.

[0038]

In a projection exposure apparatus of the present invention, (1-1) a pattern on a reticle is illuminated with light from a light source as a predetermined illumination light beam by an illumination optical system, and the pattern is projected by a projection lens. In a projection exposure apparatus that projects and exposes on a photosensitive object, at least a part of the light source and the illumination optical system is substantially sealed with a container, and the inside of the container is filled with an inert gas having a pressure higher than the pressure outside the container, and detection is performed. It is characterized in that the pressure of the inert gas supply line into the container and / or the container is detected by a container.

In particular, (1-1-1) there are a plurality of containers, and the plurality of containers are connected to each other by piping. (1-1-2) The pipe is a flexible pipe. (1-1-3) There are a plurality of the containers, each of the plurality of containers has the supply line, and the detector is provided for each supply line or each container. (1-1-4) The light source is put in one of the containers. (1-1-5) The pressure value detected by the detector is displayed on the display. (1-1-6) When the pressure value detected by the detector is abnormal, the abnormality is displayed on the display. (1-1-7) Supply of electric power to the light source is controlled based on the pressure value detected by the detector. (1-1-8) When the pressure value detected by the detector is abnormal, the power supply to the light source is stopped. (1-1-9) The supply of the inert gas through the supply line is controlled based on the pressure value detected by the detector. (1-1-10) When the pressure value detected by the detector is abnormal, the supply line is closed to stop the supply of the inert gas. It is characterized by such things.

Further, in the projection exposure apparatus of the present invention, (1-2) the reticle is illuminated with the light from the light source as a predetermined illumination light flux by the illumination optical system, and the alignment optical system is used by using the light from the light source. In a projection exposure apparatus that detects a relative position between a reticle and a photosensitive object, adjusts the positions of both, and projects a pattern on the reticle onto the photosensitive object by a projection lens to expose at least a part of the illumination optical system. / Or at least a part of the alignment optical system is substantially sealed with a container, the inside of the container is filled with an inert gas having a pressure higher than the pressure outside the container, and the inside of the container and / or the inside of the container is detected by a detector. It is characterized by detecting the pressure of the inert gas supply line.

In particular, (1-2-1) there are a plurality of the containers, each of the plurality of containers has the supply line, and the detector is provided for each supply line or each container. (1-2-2) The pressure value detected by the detector is displayed on the display. (1-2-3) If the pressure value detected by the detector is abnormal, the abnormality is displayed on the display. (1-2-4) Supply of electric power to the light source is controlled based on the pressure value detected by the detector. (1-2-5) When the pressure value detected by the detector is abnormal, the power supply to the light source is stopped. (1-2-6) The supply of the inert gas through the supply line is controlled based on the pressure value detected by the detector. (1-2-7) When the pressure value detected by the detector is abnormal, the supply line is closed to stop the supply of the inert gas. (1-2-8) Light is guided from the light source to the illumination optical system by a flexible fiber. (1-2-9) The alignment optical system has a flexible fiber that guides light. (1-2-10) The alignment optical system is divided into a drive unit and a fixed unit, and a flexible fiber guides light between the drive unit and the fixed unit. (1-2-11) The light source is an excimer laser. It is characterized by such things.

Further, the device manufacturing method of the present invention is characterized by using the projection exposure apparatus according to any one of (1-3) (1-1) to (1-2-11). I am trying.

Further, the illuminating device of the present invention is (1-4) In an illuminating device for illuminating an object to be illuminated with light from a light source as a predetermined illumination luminous flux by an illumination optical system, at least the light source and the illumination optical system. Part of the container is substantially sealed, and the inside of the container is filled with an inert gas having a pressure higher than the pressure outside the container, and a detector is used to supply the inert gas into the container and / or into the container. It is characterized by detecting pressure.

In particular, (1-4-1) there are a plurality of the containers, and the plurality of containers are connected to each other by piping. (1-4-2) There are a plurality of the containers, each of the plurality of containers has the supply line, and the detector is provided for each supply line or each container. (1-4-3) The light source is put in one of the containers. (1-4-4) The pressure value detected by the detector is displayed on the display. (1-4-5) When the pressure value detected by the detector is abnormal, the abnormality is displayed on the display. (1-4-6) The supply of electric power to the light source is controlled based on the pressure value detected by the detector. (1-4-7) The power supply to the light source is stopped when the pressure value detected by the detector is abnormal. (1-4-8) The supply of the inert gas through the supply line is controlled based on the pressure value detected by the detector. (1-4-9) When the pressure value detected by the detector is abnormal, the supply line is closed to stop the supply of the inert gas. It is characterized by such things.

[0045]

1 is a schematic view of the essential portions of Embodiment 1 of a projection exposure apparatus of the present invention. In Fig. 1, 41 is a mercury lamp (discharge lamp) used as a light source, 42 is an elliptical mirror, and various dielectric materials are vapor-deposited in multiple layers on the inner surface of the elliptical mirror 42 to maximize the reflection at the wavelength of exposure light. The reflective surface is formed to obtain the rate. The light emitting point of the mercury lamp 41 is arranged at the first focus 42a of the elliptical mirror 42. Reference numerals 43 and 47 are bending mirrors, and like the elliptical mirror 42, various dielectric materials are vapor-deposited in multiple layers on the reflecting surface to form the reflecting surface. 44
Is a collimator lens and is the second focal point 42b of the elliptical mirror 42.
The divergent light from is converted into parallel light. Reference numeral 45 is a bandpass filter, which transmits only light of a required wavelength. A fly-eye lens 46 generates a large number of secondary light sources from incident parallel light. 48 is a condenser lens. A reticle 49 has a pattern (illuminated object) to be exposed and printed on one surface thereof.

The elliptical mirror 42, the bending mirrors 43 and 47, the collimator lens 44, the bandpass filter 45, the fly-eye lens 46, the condenser lens 48 and the like constitute one element of the illumination optical system.

Reference numeral 52 denotes a container, which substantially seals from the mercury lamp 41 to the bandpass filter 45 of the illumination optical system, and fills nitrogen gas which is an inert gas when the projection exposure apparatus operates. It has become. (It is preferable that the container is completely sealed, but it may be substantially sealed as long as the container can be maintained at a predetermined pressure). The bandpass filter 45 functions as a window of the container. 41a is a lighting device for controlling the lighting of the mercury lamp 41, 53 is a supply port of a supply line for supplying nitrogen gas to the container 52, 54 is a pressure gauge (detector) for detecting the pressure of the container 52 and the gas supply line, 55 Is an electromagnetic on-off valve, 56 is a controller for controlling the lighting device 41a and the electromagnetic on-off valve 55, and 57 is an indicator.

The operation of this embodiment will be described. First, the optical action will be described. The light emitted from the mercury lamp 41 is
After being reflected by the elliptical mirror 42, it is reflected by the folding mirror 43 and condensed at the second focal point 42b to form a light source image. The divergent light from the light source image is converted into parallel light by the collimator lens 44, passes through the bandpass filter 45, becomes illumination light of a required wavelength, and enters the fly-eye lens 46.

A large number of secondary light sources are formed on the focal plane of the fly-eye lens 46. The divergent light from these secondary light sources enters the condenser lens 48 via the bending mirror 47, becomes a predetermined illumination light flux, and illuminates the pattern on the reticle 49. The pattern on the reticle 49 is imaged on a photosensitive object (wafer) (not shown) via a projection lens (not shown). The above is the optical action.

Next, the operation of the container 52 and related elements will be described. When the power of the exposure apparatus is turned on, the controller 56 opens the electromagnetic on-off valve 55 to supply nitrogen gas to the container 52 from the supply port 53. The inside of the container 52 maintains a higher pressure than the outside. This prevents air containing a substance that causes fogging from the outside from flowing into the container 52.

In the present embodiment, the pressure information detected by the pressure gauge 54 connected to the container 52 is output to the controller 56, and a failure such as breakage occurs on the supply line from the container 52 and the supply port 53. If the nitrogen gas leaks and the pressure gauge 54 detects an abnormality such as a pressure drop, the controller 56
The controller 56, which has received the information, closes the electromagnetic opening / closing valve 55 to stop the supply of nitrogen gas, issues a turn-off command to the lighting device 41a, turns off the mercury lamp 41, and displays the indicator. The failure information is displayed on 57. The above is the operation of the first embodiment.

In this embodiment, the portion of the optical system where fogging is to be prevented is sealed with a container, and the atmosphere inside the container is replaced with nitrogen gas to prevent fogging of the optical element. At this time, the supply of nitrogen gas is started when the power of the light source is turned on, and the pressure inside the container is made higher than that outside, so that new air containing a substance causing fogging flows into the container. This also prevents the occurrence of fogging. After the inside of the container is replaced with nitrogen gas, the supply of nitrogen gas is switched to an amount necessary to maintain the state, and the power supply is stopped and the supply of nitrogen gas is stopped.

By the above operation, the consumption amount of nitrogen gas is minimized to reduce the running cost of the device.

Further, since only the portion of the optical element where it is desired to prevent fogging is replaced with the atmosphere of nitrogen gas, the consumption of nitrogen gas is increased as compared with the case where the entire illumination optical system is sealed with a container and replaced with nitrogen gas. The flow rate can be reduced and running costs can be greatly reduced. Further, for the above reason, a large amount of nitrogen gas is not required when replacing the nitrogen gas when the power is turned on. Therefore, a large amount of nitrogen gas is not required even if the power is turned on many times.

Further, a failure (for example, breakage of the nitrogen gas supply tube) on the container and the supply line is detected by a pressure gauge, and appropriate action is taken to avoid an adverse effect on the illumination optical system.

FIG. 2 shows a projection exposure apparatus according to Embodiment 2 of the present invention.
FIG. This embodiment is the container 52 of the first embodiment.
Is divided into two. Since the mercury lamp 41 is a consumable part, it requires periodical replacement work. On the other hand, the bending mirror 43, the collimator lens 44, and the bandpass filter 45 do not require replacement work unless there is a failure such as damage. For this reason, it is desirable that the mercury lamp 41 has a structure in which replacement workability is taken into consideration. On the other hand, since the portion after the bending mirror 43 does not need to be considered for replacement workability, it is desirable to have a structure different from that of the mercury lamp 41. Therefore, in this embodiment, the mercury lamp 41 to the bandpass filter 45 of the illumination optical system are substantially sealed by the two containers 52a and 52b.

Sealing glasses 61 and 62 are provided as windows on the divided surfaces to maintain hermeticity. Seal glass 6
Nos. 1 and 62 may fog, but if fog occurs here, wipe or replace regularly.
Considering the fogging of the seal glass,
Alternatively, there may be a case where it is advantageous to divide the container into two parts due to structural reasons. An example corresponding to such a case is the second embodiment.
Is.

The light source 41 and the illumination optical system are basically the embodiment.
Same as 1. The mercury lamp 41 and the elliptical mirror 42 are the first
In the second container 52b, the parts from the folding mirror 43 to the bandpass filter 45 are housed in the second container 52b. First
Sealing glasses 61 and 62 are arranged in the windows of the container 52a and the second container 52b, respectively, to ensure the airtightness. The first container 52a and the second container 52b are connected by a flexible pipe 63. Therefore, the nitrogen gas supplied from the supply port 53 is supplied from the first container 52a and the first container 52a to the second container 52b via the pipe 63. Other parts are the same as in the first embodiment.

The operation of this embodiment is the same as that of the first embodiment. Further, the effect of the present embodiment is the same as that of the first embodiment, but in the present embodiment, since the part requiring maintenance and the part not requiring maintenance are separately sealed with a container, the light source and Maintenance of the illumination optical system becomes easy, and the part that does not require maintenance is not contaminated, and the prevention of fogging is complete.

In the pipe 63, the first container 52a and the first container 52a
Wiring or the like for connecting the components in the second container 52b can be routed.

Further, in the second embodiment, two containers are connected by the pipe 63, but a supply port, a solenoid on-off valve, and a pressure gauge are attached to each of the two containers, and the same effect can be obtained as an independent gas supply system for each container. Is obtained.

The portion from the light source 41 to the condenser lens 48 in Embodiments 1 and 2 can be used as an illumination device in an optical device other than the projection exposure device.

FIG. 3 shows a third embodiment of the projection exposure apparatus of the present invention.
FIG. In FIG. 3, 1 is a light source,
It is composed of an excimer laser. 2 is a diverging lens, 3, 5,
8 is a lens and 4, 9 and 11 are mirrors. 10 is a fly-eye lens that forms a large number of secondary light sources. Reference numeral 12 is a condenser lens, and 13 is a reticle, and a pattern (illumination object) to be projected and printed is formed on one surface thereof. 13
a is a mark for alignment provided on the reticle 13. 14 is a projection lens. Reference numeral 19 is a wafer (photosensitive object), and 15 is a stage for moving the wafer 19. Reference numeral 16 is an interferometer that detects the amount of movement of the stage 15, and 17 is a drive device that drives the stage. Reference numeral 18 is a reference mark for alignment provided on the stage 15. Reference numeral 19a is an alignment mark on the wafer 19.

Divergence lens 2, lenses 3, 5, 8 and mirrors 4, 9,
11, the fly-eye lens 10, the condenser lens 12, etc. constitute one element of the illumination optical system, and the light source 1, the illumination optical system, the reticle 13, the projection lens 14, etc. constitute one element of the projection optical system. .

38a is the first container, and the diverging lens 2,
Lens 3,5, mirror 4, mirror 6, condenser lens 21, 22
Is stored in it and is almost sealed. 38b is the second container, lens 8, mirror 9, fly-eye lens 10
, A mirror 11 and a condenser lens 12 are housed therein and are substantially sealed. When operating the present embodiment, the inside of the first container 38a and the second container 38b is replaced with an inert gas such as nitrogen gas, and the pressure is made higher than the pressure outside the container so that the excimer laser light and normal This prevents fogging of the optical element due to the air atmosphere. Although transparent windows are provided in the portions of the first container 38a and the second container 38b where light enters and exits, they are not shown in the figure.

The first container 38a and the second container 38b may be integrated. Also, it may be divided into smaller pieces.

Reference numerals 21 and 22 are condenser lenses, and 23 is a flexible fiber for guiding illumination light. 24 and 26 are objective lenses, 25 is a half mirror, 27 is a mirror, and 28 is a lens. Reference numeral 29 is a camera that captures an alignment image, and 30 is a processing device that calculates the amount of misalignment of the alignment mark.

The objective lens 24, the half mirror 25, the objective lens 26, the mirror 27, the lens 28, the camera 29 and the like constitute one element of the observation optical system, and the observation optical system and the condenser lenses 21 and 22.
, The fiber 23 and the like constitute one element of the alignment optical system.

The observation optical system and the processing device 30 are housed in a third container 31 in a substantially hermetically sealed manner, and the third container 31 is driven to a predetermined position by a driving device 32 during alignment. The observation optical system and the processing device constitute one element of the driving portion of the alignment optical system, and the condenser lenses 21 and 22 constitute one element of the fixing portion of the alignment optical system. A flexible fiber 23 guides light between the drive unit and the fixed unit. In addition, there is a third gap between the mirror 27 and the reticle 13.
Although there is a window of the container 31 of FIG. When operating this embodiment, the inside of the third container 31 is replaced with an inert gas such as nitrogen gas, and the pressure is made higher than the pressure outside the container to make an optical element using excimer laser light and a normal air atmosphere. Prevents the occurrence of cloudiness.

Reference numeral 6 denotes a mirror, which is driven by the driving device 7 and switches the light to the alignment optical system when it moves into the optical path of the light from the excimer laser 1. 20 is light source 1
In addition to the above, the control device controls each drive device, the interferometer 16, the processing device 30, and the like.

The operation of this embodiment will be described. First, the operation of the projection optical system will be described. The pulsed light from the excimer laser 1 whose lighting is controlled by the control device 20 is spread to an appropriate size by the diverging lens 2, and the lens 3, the mirror 4 and the lens
It is guided to the fly-eye lens 10 via 5, 8 and the mirror 9. Uniform illumination light generated by a large number of secondary light sources formed by the fly-eye lens 10 passes through the mirror 11 and the condenser lens 12 and becomes a predetermined illumination light flux to illuminate the pattern on the reticle 13.

The pattern on the reticle 13 is the projection lens 14
Projected onto the wafer 19. The controller 20 monitors the position of the stage 15 with the interferometer 16 and sends a control signal to the driver 17 to drive the stage 15.

The stage 15 is driven so as to repeat step and repeat. Excimer laser 1 is the stage
It is controlled to emit light in synchronization with the driving of 15. By the above operation, the pattern of the reticle 13 is sequentially printed on the wafer 19.

Prior to printing, alignment is performed to position the wafer 19 at the correct position. This will be described. The alignment optical system includes alignment marks 13a for the reticle 13, alignment marks 19a on the wafer 19,
Alignment is performed using the alignment reference mark 18 of the stage 15.

The light for alignment is taken out by the mirror 6. The control device 20 drives the drive device 7 to drive the mirror 6
Is moved into the optical path of the illumination optical system to switch the optical path of the light from the fly-eye lens 10 side to the alignment optical system side.

As a result, the light from the excimer laser is reflected by the mirror 6 and passes through the condenser lenses 21 and 22 to the fiber.
Light is guided to the entrance of 23. The light emitted from the exit of the fiber 23 is an objective lens 24, a half mirror 25, an objective lens 26,
The mark 13a is illuminated via the mirror 27. The light illuminating the mark 13a is further illuminated by the projection lens 14 to the alignment mark 19a on the wafer and the alignment reference mark 18 of the stage 15.

The return light from each mark returns again to the half mirror 25 via the projection lens 14, the mirror 27, and the objective lens 26, where it is reflected and focused by the lens 28 on the image pickup surface of the camera 29.

The image signal from the camera 29 is arithmetically processed by the processing device 30 to calculate the positional deviation amount of each mark. The result is sent to the control device 20, which feeds the displacement amount to the drive device 17,
Correct the position shift amount of 19. The above is the description of the alignment operation.

In this embodiment, in the conventional example shown in FIG. 9, light is guided to the alignment optical system by lenses 21, 22a to 22f, a mirror 33,
The difference is that what we did with 34 is done with fiber. Therefore, in this embodiment, the light introducing portion (lenses 21, 22a to 22f, the mirror,
It is not necessary to seal 33, 34) and replace it with nitrogen gas to prevent fogging.

Therefore, the volume of the portion that needs to be replaced with nitrogen gas can be significantly reduced, and the required gas amount can be reduced.

Further, the decrease in the volume of the closed portion means that
Since the area of the sealing portion for sealing is also reduced, the possibility that nitrogen gas leaks is reduced, which also reduces the consumption of nitrogen gas.

Further, each of the illumination optical system and the observation optical system, which is a part of the alignment optical system, is sealed with a container,
Alternatively, the structure can be simplified because the structure may be a substantially closed structure (the container is preferably closed, but may be closed as long as the inside of the container can be maintained at a predetermined pressure).

In the conventional example of FIG. 9, if the alignment optical system is made to have a hermetically sealed structure and nitrogen gas is to be replaced, the space between the condenser lens 21 and the mirror 34 should be hermetically or substantially hermetically sealed and the space between them should be kept constant. It is necessary to make the structure expandable and contractable and replace it with nitrogen gas to have a complicated structure.

On the other hand, in this embodiment, since the illumination light is guided by the fiber even when the third container 31 is driven for alignment, it is not necessary to replace it with nitrogen gas during this period, and it is simple. It becomes a simple structure.

Each container 38 filled with an inert gas
a, 38b, and 31 are pressure gauges (detectors) that detect the pressure in the inert gas supply line and each container as in the first and second embodiments.
If an abnormality occurs in the pressure, the abnormality is immediately displayed on the display device (not shown), the power supply to the light source 1 is stopped, and the supply of the inert gas to each container is also stopped.

FIG. 4 shows a projection exposure apparatus according to Embodiment 4 of the present invention.
FIG. This embodiment is different from the third embodiment in that the light source 1 composed of an excimer laser is used as a clean room.
The point is that it is installed outside 35 and the light from the light source is guided to the lens 3 of the exposure apparatus main body by a flexible fiber.

The clean room in which the projection exposure apparatus is installed is
Highly controlled temperature, humidity and cleanliness are required. Therefore, in order to reduce the running cost of equipment, it is desirable to reduce the volume of the clean room as much as possible. Therefore, it is advantageous for environmental management to install the excimer laser 1 separately from the exposure apparatus main body outside the clean room.

Fluorine gas or the like is used to emit light from the excimer laser 1. This gas is harmful to the human body, and if leaked, it corrodes each part of the exposure apparatus. It is advantageous to install and manage it in the. For the above reason, in the present embodiment, the excimer laser that is the light source 1 is installed outside the clean room.

In FIG. 4, 35 is a clean room,
The main body of the exposure equipment except the excimer laser is installed in it. Reference numeral 37 denotes a condenser lens, and 36 denotes a flexible fiber, which is configured so that the diverging light from the exit thereof is received by the lens 3 of the illumination optical system. Other points are Embodiment 3
Is the same as.

In the present embodiment, the excimer laser which is the light source 1 is located outside the clean room 35, for example, in an environment of temperature, humidity and cleanliness different from the clean room (the management standard is looser than in the clean room). Install in a work area for maintenance. The pulsed light from the excimer laser 1 is guided to the entrance of the fiber 36 through the condenser lens 37, guided into the clean room 35 by the fiber 36, and the divergent light from the exit of the fiber 36 is received by the lens 3. To introduce and connect light to the illumination optical system. The subsequent operation is the same as that of the third embodiment.

If an excimer laser 1 installed outside the clean room 35 guides light into the clean room 35 by an optical system using a mirror, and the mirror part is sealed with a container and replaced with nitrogen gas to cause fogging. To prevent this, the volume of the container becomes very large, and the flow rate of nitrogen gas consumed becomes large.

On the other hand, according to this embodiment, since this portion is replaced with the fiber, it is not necessary to hermetically close and replace with the nitrogen gas. Therefore, the consumption flow rate of nitrogen gas can be significantly reduced.

Further, when light is guided to the clean room 35 by an optical system using a mirror, an optical path detoured by the mirror must be secured, and the number of construction design man-hours, construction time,
Although the construction cost is disadvantageous, in this embodiment, since the flexible fiber is used, there are few restrictions on the installation location of the excimer laser emitting section, and the application to equipment is easy.
That is, even if there is an obstacle, such as a pillar, a wall, a floor, or a pipe that has already been installed, on the light guide optical path from the excimer laser 1, it can be bypassed easily.

FIG. 5 is a schematic view of a main part of a semiconductor device manufacturing system using the third embodiment. This system is a system for manufacturing a semiconductor device by printing a circuit pattern provided on an original plate such as a reticle or a photomask on a wafer. The system roughly includes a projection exposure apparatus, an original plate storage device, an original plate inspection device, and a controller, which are arranged in a clean room.

In the figure, reference numeral 920 is the third embodiment of the projection exposure apparatus.

Reference numeral 914 is an original plate storage device, which stores a plurality of original plates inside. Reference numeral 913 is an inspection device that detects the presence or absence of foreign matter on the original plate. The inspection device 913 inspects foreign matter on the original plate before the selected original plate is pulled out from the storage device 914 and set at the exposure position of the projection exposure apparatus.

Reference numeral 918 denotes a controller, which controls the sequence of the entire system, and includes a storage device 914 and an inspection device.
Operation command of 913 and control device 20 of projection exposure apparatus 920
Are controlled to control the sequence of basic operations such as alignment, exposure, and step feed of the wafer.

The manufacturing process of a semiconductor device using this system will be described below.

FIG. 6 is a flow chart showing the manufacturing process of a semiconductor device (semiconductor chip such as IC or LSI, liquid crystal panel or CCD). This will be described. Step 1 (Circuit design): Design circuits for semiconductor devices. Step 2 (mask production): A mask (original plate 13) on which the designed circuit pattern is formed is produced. Step 3 (wafer manufacturing): A wafer is manufactured using a material such as silicon. Step 4 (wafer process): This process is called the pre-process, and the mask (reticle) prepared with the above projection exposure apparatus is used.
An actual circuit is formed on the wafer by lithography using the wafer and the wafer. Step 5 (Assembly): This step is called a post-step, and is a step of making a chip by using the wafer made by Step 4, such as an assembly step (dicing, bonding), a packaging step (chip encapsulation), etc. including. Step 6 (Inspection): Conduct operation inspection, durability test, and other inspections of the semiconductor device created in Step 5. Step 7 (shipment): The semiconductor device is completed and shipped.

FIG. 7 is a detailed flow chart of the wafer process. This will be described. Step 11 (oxidation): The surface of the wafer is oxidized. Step 12 (CVD): An insulating film is formed on the surface of the wafer. Step 13 (electrode formation): An electrode is formed on the wafer by vapor deposition. Step 14 (ion implantation): implant ions into the wafer. Step 15 (resist processing): Resist wafer (sensitive material)
Is applied to form a photosensitive substrate. Step 16 (exposure): The projection exposure apparatus 920 exposes a reduced image of the circuit pattern of the mask (original plate 13) on the wafer 19. Step 17 (Development): The exposed wafer 19 is developed. Step 18 (Etching): Scrap off parts other than the developed resist. Step 19 (resist stripping): Remove the unnecessary resist after etching.

As shown in the figure, a circuit pattern is formed on the wafer by repeating these steps.

The step 16 exposure step will be described in more detail. In the projection exposure apparatus shown in FIG.
Take out the original plate 13 to be used from 4 and set it on the inspection device 913.

Next, the inspection device 913 inspects the foreign matter on the original plate 13. When it is confirmed as a result of the inspection that there is no foreign matter, this original plate is set at the exposure position of the projection exposure apparatus.

Next, a wafer, which is the exposure target, is placed on the stage 15.
Set 19. Then, the stage 15 is stepwise fed by the step & repeat method, the original plate (reticle) 13 and the wafer 19 are aligned (alignment), and the pattern of the original plate is reduced and projected to be exposed. This operation is repeated.

When the entire surface of one wafer 19 is exposed,
This is accommodated and a new wafer is supplied, and similarly, the exposure of the pattern of the original plate is repeated by the step & repeat method.

The exposure process is completed as described above, and the exposed wafer 19 that has been exposed is sent to the next developing process.

According to the present system using the projection exposure apparatus according to the third embodiment, the performance of the optical system is not deteriorated and the high resolution is exhibited. Therefore, it is possible to achieve a high degree of integration having a very fine circuit pattern which has been difficult to manufacture in the past. The semiconductor device can be manufactured.

In the first and second embodiments of the exposure apparatus of the present invention, each element from the light source 41 to the condenser lens 48 in the order of passage of the illumination light, the container filled with the inert gas, the supply line related to this, the detector, The display unit and the like constitute an illuminating device, and in the third and fourth embodiments of the present invention, each element from the light source 1 to the condenser lens 12 in the order of passage of the illumination light and the containers 38a and 38b that fill the inert gas and the related elements. Supply line,
The detector, the display, and the like constitute a lighting device.

[0109]

According to the present invention having the above-mentioned structure, the light source, the illumination optical system, and / or the main optical elements of the alignment optical system are used in a nitrogen atmosphere, and the illumination efficiency due to the fogging of the optical elements occurs. (EN) A projection exposure apparatus that prevents deterioration of alignment accuracy, realizes high resolution, reduces nitrogen consumption at that time, and reduces equipment running cost.

Others (2-1) The part of the optical component where it is desired to prevent fogging is housed in a container having a closed or substantially closed structure, and the pressure is made higher than the outside of the container so that the inside of the container is fogged. Prevents the inflow of new air containing substances that cause (2-2) Since only the portion of the optical component of the illumination optical system where it is desired to prevent fogging is sealed with the container, compared with the case where the entire illumination optical system is sealed with the container and replaced with an inert gas, The flow rate consumed can be reduced, and the running cost can be greatly reduced. (2-3) By using a plurality of containers, the maintenance of the light source and the illumination optical system is facilitated, and the prevention of fogging of the optical components becomes more complete. (2-4) Even if a failure such as breakage occurs in the container in which the optical parts are hermetically sealed and filled with an inert gas or the supply line itself, the abnormality is detected and an appropriate action is taken. (2-5) By using a flexible fiber for the light guide portion in the alignment optical system, even if the alignment optical system has a mechanism for moving, the moving portion of the alignment optical system is sealed with a container to Since the inside of the container can be replaced with an inert gas, it is possible to prevent fogging of the main optical components of the alignment optical system and prevent the alignment accuracy from degrading. (2-6) When an excimer laser is used as the light source, the excimer laser emitting portion can be installed outside the clean room with easy construction. Further, at this time, by guiding the light from the laser emission unit to the exposure apparatus main body with a flexible fiber, the light guide unit from the excimer laser is sealed with a container to prevent fogging of optical components without replacing with an inert gas atmosphere. It can be completely prevented. (2-7) Since the volume of the portion which is sealed with the container and replaced with nitrogen gas is small, the replacement time is short and the amount of nitrogen gas used is small. A projection exposure apparatus having at least one of the above effects is achieved.

Further, by using the projection exposure apparatus of the present invention, high resolution can be obtained without deterioration of the performance of the optical system.
To achieve a device manufacturing method capable of manufacturing a highly integrated semiconductor device, which has been difficult to manufacture in the past.

Furthermore, by using the light source and the main optical elements of the illumination optical system in a nitrogen atmosphere, it is possible to achieve an illuminating device that prevents the reduction of the illumination efficiency due to clouding of the optical elements.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a main part of a first embodiment of a projection exposure apparatus of the present invention.

FIG. 2 is a schematic view of the essential portions of Embodiment 2 of the projection exposure apparatus of the present invention.

FIG. 3 is a schematic view of a main part of a third embodiment of a projection exposure apparatus of the present invention.

FIG. 4 is a schematic view of the essential portions of Embodiment 4 of the projection exposure apparatus of the present invention.

FIG. 5 is a schematic view of a main part of a semiconductor device manufacturing system using a projection exposure apparatus according to a third embodiment of the present invention.

FIG. 6 is a flowchart of a semiconductor device manufacturing process.

FIG. 7 is a detailed flowchart of a wafer process.

FIG. 8 is a schematic view of a main part of a light source and an illumination optical system of a conventional projection exposure apparatus.

FIG. 9 is a schematic view of a main part of a conventional projection exposure apparatus.

[Explanation of symbols]

1: Excimer laser 41,71: Mercury lamp 2: Divergence lens 41a: Lighting device 3, 5, 8: Lens 42,72: Elliptical mirror 4, 6, 9, 11, 27: Mirror 42a, 72a: 1st
Focus 10: Fly-eye lens 42b, 72b: No.
2 Focus 12: Condenser lens 43,47,73,77
: Bending mirror 13: Reticle 44,74: Collimator lens 13a: Registration mark on reticle 45,75: Bandpass filter 14: Projection lens 46,76: Fly's eye lens 15: Stay 48,78: Condenser lens 16: Interferometer 49, 79: Reticle 17: Stage drive device 52: Container 18: Reference mark for alignment 52a: First container 19: Wafer 52b: Second container 19a: Registration mark on wafer 53: Supply port 20: Control device 54: Pressure gauges 21, 22: Condenser lens 55: Electromagnetic on-off valves 22a to 22f: Lens 23: Fiber 56: Controllers 24, 26: Objective lens 57: Display unit 25: Half mirrors 61, 62 : Seal glass 28: Lens 63: Pipe 29: Camera 913: Inspection device 30: Processing device 914: Original plate storage device 31: Third container 918: Controller 32: Drive device 920: Embodiment of projection exposure apparatus of the present invention 3 33, 34: Mirror 35: Clean Arm 36: Fiber 37: condenser lens 38a: first container 38b: second container

Continuation of the front page (56) Reference JP-A-8-55792 (JP, A) JP-A-7-74077 (JP, A) JP-A-8-279459 (JP, A) JP-A-2-77809 (JP , A) JP 6-333800 (JP, A) JP 1-212436 (JP, A) JP 9-162117 (JP, A) JP 6-260385 (JP, A) JP 7-29804 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/027 G03B 27/54 G03F 7/20 521

Claims (34)

(57) [Claims] 1. A projection exposure apparatus for illuminating a pattern on a reticle with a light from a light source as a predetermined illumination light flux by an illumination optical system and projecting and exposing the pattern onto a photosensitive object by a projection lens, the light source and the illumination. At least a part of the optical system is substantially sealed with a container, the inside of the container is filled with an inert gas having a pressure higher than the pressure outside the container, and the inert gas in and / or into the container is detected by a detector. A projection exposure apparatus characterized by detecting the pressure of the supply line of the. 2. The container is plural, and the plural containers are connected to each other by piping.
Projection exposure equipment. 3. The projection exposure apparatus according to claim 2, wherein the pipe is a flexible pipe. 4. The container has a plurality of containers, each of the plurality of containers has the supply line, and the detector is provided for each supply line or each container. Projection exposure equipment. 5. The projection exposure apparatus according to claim 1, wherein the light source is contained in one of the containers. 6. The projection exposure apparatus according to claim 1, wherein a pressure value detected by the detector is displayed on a display. 7. The projection exposure apparatus according to claim 6, wherein when the pressure value detected by the detector is abnormal, the abnormality is displayed on the display. 8. The projection exposure apparatus according to claim 1, wherein the supply of electric power to the light source is controlled based on a pressure value detected by the detector. 9. The projection exposure apparatus according to claim 8, wherein the power supply to the light source is stopped when the pressure value detected by the detector is abnormal. 10. The projection according to claim 1, wherein the supply of the inert gas through the supply line is controlled based on the pressure value detected by the detector. Exposure equipment. 11. The projection exposure apparatus according to claim 10, wherein the supply line is closed to stop the supply of the inert gas when the pressure value detected by the detector is abnormal. 12. An illumination optical system illuminates a reticle as a predetermined illumination light flux with an illumination optical system, and the alignment optical system uses the light from the light source to detect a relative position between the reticle and a photosensitive object. Of the illumination optical system and / or at least a part of the alignment optical system in a container in a projection exposure apparatus that adjusts the position of Substantially sealed, filling the inside of the container with an inert gas at a pressure higher than the pressure outside the container,
A projection exposure apparatus, wherein a pressure of a line for supplying the inert gas into the container and / or the container is detected by a detector. 13. The container according to claim 12, wherein the plurality of containers are provided, each of the plurality of containers has the supply line, and the detector is provided for each supply line or each container. Projection exposure equipment. 14. The pressure value detected by the detector is displayed on a display.
Projection exposure equipment. 15. The projection exposure apparatus according to claim 14, wherein when the pressure value detected by the detector is abnormal, the abnormality is displayed on the display. 16. The projection exposure apparatus according to claim 12, wherein supply of electric power to the light source is controlled based on a pressure value detected by the detector. 17. The projection exposure apparatus according to claim 16, wherein the power supply to the light source is stopped when the pressure value detected by the detector is abnormal. 18. The supply of the inert gas through the supply line is controlled based on the pressure value detected by the detector, according to any one of claims 12 to 17. Projection exposure device. 19. The projection exposure apparatus according to claim 18, wherein when the pressure value detected by the detector is abnormal, the supply line is closed to stop the supply of the inert gas. 20. The projection exposure apparatus according to claim 12, wherein light is guided from the light source to the illumination optical system by a flexible fiber. 21. The projection exposure apparatus according to claim 12, wherein the alignment optical system has a flexible fiber that guides light. 22. The alignment optical system is divided into a drive section and a fixed section, and light is guided between the drive section and the fixed section by a flexible fiber. The projection exposure apparatus according to claim 1. 23. The projection exposure apparatus according to claim 12, wherein the light source is an excimer laser. 24. A method of manufacturing a device, wherein the projection exposure apparatus according to claim 1 is used. 25. An illumination device for illuminating an object to be illuminated with light from a light source as a predetermined illumination light flux by an illumination optical system, wherein at least a part of the light source and the illumination optical system is substantially sealed with a container, and Is filled with an inert gas having a pressure higher than the pressure outside the container, and the pressure of the supply line of the inert gas into the container and / or the container is detected by a detector. 26. The lighting device according to claim 25, wherein there are a plurality of the containers, and the plurality of containers are connected to each other by piping. 27. The container has a plurality of containers, each of the plurality of containers has the supply line, and the detector is provided for each supply line or each container. Lighting equipment. 28. The lighting device according to claim 25, wherein the light source is placed in one of the containers. 29. The lighting device according to claim 25, wherein a pressure value detected by the detector is displayed on a display. 30. The lighting device according to claim 29, wherein when the pressure value detected by the detector is abnormal, the abnormality is displayed on the display. 31. The lighting device according to claim 25, wherein the supply of electric power to the light source is controlled based on a pressure value detected by the detector. 32. The lighting device according to claim 31, wherein the power supply to the light source is stopped when the pressure value detected by the detector is abnormal. 33. The illumination according to claim 25, wherein the supply of the inert gas through the supply line is controlled based on a pressure value detected by the detector. apparatus. 34. The lighting device according to claim 33, wherein when the pressure value detected by the detector is abnormal, the supply line is closed to stop the supply of the inert gas.