JP3275838B2 - Light irradiation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light irradiation device incorporated in an exposure device used for manufacturing a semiconductor device, a printed circuit board, a liquid crystal substrate and the like.

[0002]

2. Description of the Related Art An exposure apparatus used for manufacturing a semiconductor device, a printed circuit board, a liquid crystal substrate or the like irradiates a workpiece (work) with light from a discharge lamp of a built-in light irradiating apparatus to perform exposure. FIG. 1 shows an example of a light irradiation device. Discharge lamp 1
Uses a short arc type ultra-high pressure mercury lamp,
As the condenser mirror 2, an elliptical condenser mirror made of glass is used. The discharge lamp 1 is arranged so that the emission center is located at the first focal point of the condenser mirror 2. The condensing mirror 2 is a cold mirror which reflects only light containing ultraviolet light necessary for exposure and forms a vapor-deposited film which reflects ultraviolet light and transmits infrared light on the surface of the reflection surface in order to remove unnecessary heat rays. Is often used.

Light including ultraviolet rays emitted from the discharge lamp 1 is condensed by the condenser mirror 2 and reaches the first plane mirror 91. The light reflected by the first plane mirror 91 is collected near an incident part of an integrator lens 92 provided to make the illuminance distribution in the irradiation area uniform. When the shutter mechanism 93 disposed behind the integrator lens 92 is opened, the light emitted from the integrator lens 92 is converted into parallel light by the collimator lens 95 via the second plane mirror 94 and the work placed on the light irradiation surface. Starts, and ends when the shutter mechanism 93 is closed. Note that the shutter mechanism 93 may be arranged in front of the integrator lens 92.

Here, since the ultrahigh pressure mercury lamp as the discharge lamp 1 is lit in a vertical position, the condenser mirror 2 is arranged with its opening facing upward or downward, as shown in FIG. In order to reduce the height H from the upper end of the light irradiation device to the light irradiation surface, that is, to reduce the overall height of the light irradiation device, the light-collecting mirror 2 is disposed with the opening thereof facing upward, and the light is collected. The light irradiated upward from the mirror 2 is turned downward by the first plane mirror 91 and the second plane mirror 94 to irradiate the work placed on the light irradiation surface. If the opening of the condenser mirror 2 is arranged downward and the work placed on the light irradiation surface is irradiated without turning back the light emitted downward from the condenser mirror 2, the vertical optical path becomes Not only does the length of the light irradiation device become longer, the overall height of the light irradiation device becomes higher, but also the discharge lamp 1 is arranged at a higher position, so that maintenance such as replacement of the discharge lamp 1 is difficult to perform.

FIG. 2 and FIG. 3 which is an enlarged view of a portion A in FIG.
Shows a conventional example of a mounting structure when the condenser mirror 2 is arranged with its opening facing upward. A converging mirror mounting plate 3 having a light irradiation opening 31 is fixed to the device, and the converging mirror mounting plate 3 serves as a positioning plate for the converging mirror 2. Focusing mirror 2
The peripheral edge 21 of the opening abuts against the peripheral edge 32 of the light irradiation opening 31 of the condenser mirror mounting plate 3, thereby positioning the condenser mirror 2. As shown in FIG. 3, a plurality of substantially inverted L-shaped mounting brackets 39 made of a metal plate rich in resilience are fixed to the converging mirror mounting plate 3. 39a is in pressure contact with the inclined outer surface of the condenser mirror 2, and holds the condenser mirror 2 by the pressure contact force. In other words, the gravity of the condenser mirror 2 is supported by the vertical component of the pressing force of the mounting bracket 39 against the condenser mirror 2, and the peripheral edge 2 of the opening of the condenser mirror 2 is supported.
The holding force increases as the inclination angle of the outer surface near 1 increases.

[0006]

In recent years, with the enlargement and large-diameter of semiconductor wafers and liquid crystal substrates as works, a light irradiation apparatus capable of exposing a large area has been required. . When the irradiation area is increased, the illuminance decreases and the exposure time becomes longer. Therefore, a large discharge lamp having a large emission power is used, and consequently each optical component such as a condensing mirror constituting an optical mechanism is also used. Increase in size. That is, a heavy condensing mirror is used.

Further, since it is necessary to effectively condense the light of the discharge lamp, the discharge lamp is sufficiently covered with a converging mirror, and as much as possible on the reflecting surface of the converging mirror without losing the radiation of the discharge lamp. There is a tendency to use condensing mirrors that are deep and long in length so that they can be reflected. However, if the total length of the converging mirror having an elliptical cross section is increased, the inclination angle of the outer surface near the opening edge of the converging mirror becomes smaller as it approaches vertical. Accordingly, the vertical component of the pressing force of the mounting member 39 against the condenser mirror 2 is reduced, and the holding force by the mounting member 39 is reduced. Further, a focusing mirror having a large distance between the first focal point and the second focal point has a large ratio of the major axis to the minor axis, is long and thin, and has a small inclination angle of the outer surface. Is the same.

Next, when the power of the discharge lamp is increased, the optical components and the pressing members of the optical components are strongly heated to a high temperature during the operation of the lamp. Therefore, FIGS. 2 and 3
The converging mirror mounting plate 3 and the converging mirror 2 shown in FIG. However, since the condenser mirror mounting plate 3 is formed of a metal plate, while the condenser mirror 2 is made of glass, the difference in the coefficient of thermal expansion between the two is large. Although the inner diameter of the light irradiation opening 31 of the plate 3 is considerably large, the outer diameter of the opening of the condenser mirror 2 is not so large. Therefore, the mounting bracket 39 fixed to the collector mounting plate 3 moves relatively outward from the peripheral edge 21 of the opening of the collector mirror 2, so that the pressing force of the mounting bracket 39 is reduced.

As described above, the weight of the condenser mirror 2 is large, and the inclination angle of the outer surface near the peripheral edge 21 of the opening of the condenser mirror 2 becomes smaller as it approaches the vertical direction. Since the mounting bracket 39 moves relatively outward from the peripheral edge 21 of the opening of the condenser mirror 2 and the holding force of the mounting bracket 39 decreases, the condenser mirror 2 may be shifted downward by its own weight. That is, the condenser mirror 2 moves away from the regular position away from the condenser mirror mounting plate 3 which is a positioning plate. On the other hand, since the discharge lamp 1 is held independently of the focusing mirror 2,
The emission center of the discharge lamp 1 is deviated from the first focal position of the condenser mirror 2 so that the light is not accurately focused on the second focal point, and the light focusing characteristic is deteriorated.

When the lamp is turned on, the inner diameter of the light irradiation opening 31 of the condenser mirror mounting plate 3 increases due to thermal expansion, but when turned off, the inner diameter of the light irradiation opening 31 of the condenser mirror mounting plate 3 is restored. When the inner diameter of the light irradiation opening 31 is enlarged, the converging mirror 2 is shifted downward as described above. However, since the outer surface of the converging mirror 2 is inclined, a larger diameter portion is attached to the converging mirror. It comes into contact with the peripheral edge 32 of the light irradiation opening 31 of the plate 3. When the inner diameter of the light irradiation opening 31 of the condenser mirror mounting plate 3 is restored by turning off the light, the peripheral edge 21 of the opening of the condenser mirror 2 is compressed inward, and the condenser mirror 2 may be damaged.

Therefore, according to the present invention, a heavy condensing mirror arranged with the opening facing upward can be accurately held even when it is turned on, and the condensing mirror has good light collecting characteristics and is not damaged. It is an object to provide a light irradiation device.

[0012]

In order to achieve the above object, according to the present invention, there is provided a short arc type discharge lamp and a light irradiation device having an optical mechanism for projecting light of the discharge lamp. A glass condensing mirror that constitutes a part of the mechanism is placed with its opening facing upward, and the lower end of the condensing mirror is suspended by a column on a converging mirror mounting plate that is a positioning plate. The mirror support plate is pressed upward by a pressing member resiliently pressed by a compression spring, and the periphery of the opening at the upper end of the condenser mirror is pressed against and held against the periphery of the light irradiation opening of the condenser mirror mounting plate.

In the case where the condenser mirror is a cold mirror that reflects ultraviolet rays and transmits infrared rays, the pressing member according to the first aspect of the present invention is made of a heat-resistant material having low thermal conductivity. It is preferable that a soft light reflecting plate is formed on the surface of the pressing member that is formed and abuts against the lower end of the condenser mirror.

[0014]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 4 shows a sectional view of an embodiment of the present invention. In FIG. 4, the condenser mirror 2 arranged with the opening facing upward is made of glass and has a diameter of φ
It is a concave mirror having a depth of 500 mm and an oval cross section and a deep bottom. Therefore, the emitted light can be efficiently collected by sufficiently covering the discharge lamp 1. And on the reflective surface,
This is a cold mirror on which a deposited film that reflects ultraviolet rays and transmits infrared rays is formed. The discharge lamp 1 is an ultra-high pressure mercury lamp with a rated power consumption of 8 kW, is inserted in the center hole 22 of the condenser mirror 2 and is arranged in a vertical position. It is located at the first focus.

The light collecting mirror mounting plate 3 formed of a metal plate has a light irradiation opening 31 and its end is fixed to a base plate (not shown) of the apparatus. The lower end 2a of the condenser mirror 2 is pressed upward by a pressing member 6 described later, and the peripheral edge 21 of the opening of the condenser mirror 2 is
1 is pressed against the peripheral edge 32. Here, the condenser mirror mounting plate 3
Is fixed to the base plate of the apparatus, so that the peripheral edge 21 of the opening is
And serves as a positioning plate for the condenser mirror 2 which is pressed against the peripheral edge 32 of the mirror.

A plurality of, for example, four columns 5 are fixed downward to the condenser mirror mounting plate 3, and the condenser mirror support plate 4 is fixed to the lower end of the column 5. That is, the condenser supporting plate 4 is suspended from the condenser mounting plate 3 by the columns 5. Both the support 5 and the condenser support plate 4 are formed of an aluminum material. This is because the aluminum material has good thermal conductivity, so that it is possible to prevent thermal deformation due to non-uniform temperature distribution of the column 5 and the condensing mirror support plate 4, and it is easy to process.
However, since the aluminum material becomes weak and easily deformed when the creep strength is 200 ° C. or more, it is necessary to take measures to prevent the temperature from rising to 200 ° C. or more. By the way, stainless steel is
Although it has excellent heat resistance and high creep strength, it is not suitable as a material for the condensing mirror support plate 4 or the support post 5 because of poor thermal conductivity and easy deformation and distortion due to uneven temperature distribution. The column 5 and the condenser support plate 4 are covered with a light shielding plate (not shown).

A compression spring 7 is interposed between the pressing member 6 and the condenser mirror support plate 4, and the urging force of the compression spring 7 causes the pressing member 6 to press the condenser mirror 2 upward. Pressing member 6
Is a square plate having a central hole 61 through which the discharge lamp 1 is inserted, as shown in FIG. 5, and the central hole 61 is formed by the central hole 22 of the condenser mirror 2 and the central hole 41 of the condenser mirror support plate 4. Matches. Bolts 63 for preventing separation are inserted into the bolt holes of the condenser support plate 4 and the pressing member 6, and the compression spring 7, which is a coil spring, is disposed around the bolt 63 to repel the pressing member 6. The pressing force of the compression spring 7 is
Of course, it does not exceed the allowable stress of the glass used as the material of the condenser mirror 2 while enduring the weight of the pressing member 6.

The condenser mirror 2 is a cold mirror that transmits infrared rays, and of the light emitted from the discharge lamp 1 when the lamp is turned on, the infrared rays that pass through the condenser mirror 2 emit heat radiation or heat conduction of the condenser mirror 2. The lower end 2 of the condenser mirror 2
The temperature of the pressing member 6 that comes into contact with a is 300 ° C. or higher. For this reason, the pressing member 6 cannot be formed of an aluminum material, but is preferably formed of a heat-resistant material having low thermal conductivity, such as ceramics or carbon. Further, a soft light reflecting plate 8, for example, a bright aluminum plate, is preferably attached to the surface of the pressing member 6 on the side of the condenser mirror 2. The light reflecting plate 8 reflects the infrared rays radiated from the condenser mirror 2 and the infrared rays from the discharge lamp 1 passing through the condenser mirror 2, so that the temperature of the pressing member 6 rises, and further, the condenser mirror support plate 4 and the compression The temperature rise of the spring 7 can be suppressed. The hard and brittle glass converging mirror 2 and the ceramic pressing member 6 come into contact with each other, but since the light reflecting plate 8 is soft, this becomes a cushion material, and the converging mirror 2 is broken at the contact portion. Nothing.

When the discharge lamp 1 is turned on, of the light radiated from the discharge lamp 1, the infrared ray passing through the condenser mirror 2 causes the condenser mirror 2 to reach a temperature of 300 ° C. or more,
The radiated infrared rays are radiated behind the condenser mirror 2. Therefore, the column 5 thermally expands, and the distance between the condenser mounting plate 3 which is the positioning plate of the condenser 2 and the condenser supporting plate 4 becomes large. Since it expands and absorbs, the state where the periphery 21 of the opening of the condenser mirror 2 is pressed against the periphery 32 of the light irradiation opening 31 of the condenser mirror mounting plate 3 is maintained,
The condenser mirror 2 does not shift downward. That is, the discharge lamp held independently of the condenser mirror 2 and the condenser mirror mounting plate 3
Therefore, the positional relationship with the focusing mirror 2 positioned by the above method does not change, and the focusing property does not deteriorate.

Further, when the lamp is turned on, the inner diameter of the light irradiation opening 31 of the condenser mirror mounting plate 3 increases due to thermal expansion, and when the light is turned off, the inner diameter of the light irradiation opening 31 of the condenser mirror mounting plate 3 is restored. Even if the inside diameter of the light irradiation opening 31 of the light collecting mirror mounting plate 3 is enlarged, the light collecting mirror 2 does not shift downward. The mirror 2 is not damaged.

When the discharge lamp 1 was turned on, the temperatures of the pressing member 6, the compression spring 7, and the condenser mirror supporting plate 4 having a bright aluminum plate as the light reflecting plate 8 adhered to the surface thereof were measured. The temperature was 330 ° C., the compression spring 7 was 246 ° C., and the condenser mirror support plate 4 was 185 ° C., and the temperature of the condenser mirror support plate 4 made of aluminum material could be reduced to 200 ° C. or less. Incidentally, when the light reflecting plate 8 is not stuck on the surface of the pressing member 6, the pressing member 6 has a temperature of 415 ° C., the compression spring 7 has a temperature of 336 ° C., the converging mirror support plate 4 has a temperature of 220 ° C. 4, it was confirmed that the effect of the light reflecting plate 8 on the suppression of the temperature rise was large.

[0022]

As described above, according to the light irradiation apparatus of the present invention, the lower end of the glass condensing mirror arranged with the opening facing upward is suspended by the column on the converging mirror mounting plate as the positioning plate. It is pressed upward by a pressing member resiliently pressed by a compression spring from the provided condenser support plate, and the opening edge of the upper end of the condenser mirror is pressed against and held to the peripheral edge of the light irradiation opening of the condenser mounting plate. As a result, a heavy condensing mirror can be accurately held even during lighting, and a light irradiating device with good condensing characteristics and no damage to the converging mirror can be provided. When the condensing mirror is a cold mirror that reflects ultraviolet light and transmits infrared light, the pressing member is formed of a heat-resistant material having low thermal conductivity, and a soft surface is formed on the surface of the pressing member with which the lower end of the condensing mirror contacts. When the light reflecting plate is provided, it is possible to suppress a rise in temperature of the converging mirror support plate and the like, and also possible to prevent damage to a contact portion of the converging mirror with the pressing member.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a light irradiation device.

FIG. 2 is an explanatory diagram of a conventional example.

FIG. 3 is an enlarged view of a portion A in FIG. 2;

FIG. 4 is a sectional view of an embodiment of the present invention.

FIG. 5 is a sectional view of a main part of the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge lamp 2 Condensing mirror 2a Lower end of condensing mirror 21 Peripheral edge of opening of condensing mirror 22 Center hole of condensing mirror 3 Condensing mirror mounting plate 31 Light irradiation opening of condensing mirror mounting plate 31a Condensing mirror mounting plate Peripheral edge of light-irradiation opening 39 Mounting bracket 4 Condensing mirror support plate 41 Center hole of condensing mirror support plate 5 Prop 6 Pressing member 61 Center hole of pressing member 63 Bolt 7 Compression spring 8 Light reflecting plate

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-11-258815 (JP, A) JP-A-10-55713 (JP, A) JP-A-9-102455 (JP, A) JP-A-6-1024 320097 (JP, A) JP-A-1-117025 (JP, A) JP-A-63-121833 (JP, A) JP-A-50-22617 (JP, U) (58) Fields investigated (Int. ⁷ , DB name) H01L 21/027 G03F 7/20 521

Claims (2)

(57) [Claims] 1. A light irradiating apparatus having a short arc type discharge lamp and an optical mechanism for projecting light of the discharge lamp, wherein a glass condensing mirror constituting a part of the optical mechanism has an opening formed in the glass. While being arranged upward, the lower end of the condenser mirror is directed upward by a pressing member which is resiliently pressed by a compression spring from a condenser mirror support plate suspended from a condenser mirror mounting plate as a positioning plate by a column. A light irradiating device, wherein the light irradiating device is pressed and held so that a peripheral edge of an opening at an upper end of the condenser mirror is pressed against a peripheral edge of a light irradiation opening of the condenser mirror mounting plate. 2. The condensing mirror is a cold mirror that reflects ultraviolet light and transmits infrared light, wherein the pressing member is made of a heat-resistant material having low thermal conductivity, and the pressing member is in contact with a lower end of the condensing mirror. The light irradiation device according to claim 1, further comprising a soft light reflection plate on the surface of the light irradiation device.