JPH11338005A - Shutter mechanism of light irradiation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shutter mechanism of a light irradiation device where a shutter plate is made thin and light in weight, by which high speed opening/ closing is realized, and which is not thermally deformed even when it is used for opening/closing for the beam of light of a discharge lamp having high irradiation intensity for a long time. SOLUTION: In the rotary type shutter plate 61, a fan-shaped notched part is formed and made into a light passing part 63, and a non-notched part plate is made into a lightproof part 64, and the light incident surface of the lightproof part of the plate 61 is made into a mirror surface 65, and an infrared ray radiation film 66 is formed on the back surface of the light incident surface. The light passing part is formed between a pair of lightproof parts only by one, and the plate 61 on an opposite side to the light passing part with respect to the center of the plate 61 is formed so that the center of gravity of the plate 61 may be aligned with the center of the plate 61, then the area of the center part of the plate 61 is made large.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shutter mechanism for opening and closing a beam of light emitted from a discharge lamp of 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. It is.

[0002]

2. Description of the Related Art An exposure apparatus used for manufacturing a semiconductor device, a printed circuit board, a liquid crystal substrate, etc. irradiates a workpiece (work) with light of a discharge lamp of a built-in light irradiating apparatus to perform exposure. Since the discharge lamp cannot be repeatedly turned on and off in a short cycle, the discharge lamp is always lit, and a shutter mechanism opens and closes a beam of light emitted from the discharge lamp to perform exposure with a predetermined amount of light.

FIG. 1 shows an example of a light irradiation device. Light including ultraviolet rays emitted from the discharge lamp 1 is condensed by the condenser mirror 2 and enters the first plane mirror 4 via the concave lens 3. The light reflected by the first plane mirror 4 is condensed near an incident portion of an integrator lens 5 provided for uniforming the illuminance distribution in the irradiation area. When the shutter mechanism 6 arranged behind the integrator lens 5 opens, the light emitted from the integrator lens 5 is converted into parallel light by the collimator lens 8 via the second plane mirror 7 and the work placed on the light irradiation surface. Is started, and the irradiation ends when the shutter mechanism 6 is closed. Note that the shutter mechanism 6 may be arranged in front of the integrator lens 5.

In this light irradiation device, in order to make the exposure amount on the work surface uniform, the integrated light amount in the irradiation area of the light irradiation surface is equal during the time from opening of the shutter (start of irradiation) to closing of the shutter (end of irradiation). It is necessary to open and close the shutter mechanism in order to achieve this. For this reason, FIG.
The rotary shutter mechanism shown in FIG. That is, both sides of the disc-shaped aluminum shutter plate material are about 9
It is cut out in a fan shape at an angle of 0 °, and this cutout portion is a light passing portion 63. The remaining shutter plate 61, which is a non-notched portion, is a light shielding portion 64. That is, the shutter plate 61 includes two light passing portions 63 and two light blocking portions 64.
Are point-symmetrical shapes formed alternately, and the center of the shutter plate 61 which is the center point of the point-symmetrical shape coincides with the center of gravity.
Then, the shutter plate 61 smoothly rotates in a fixed direction about a rotation shaft 62 disposed at the center thereof in a balanced load state.

When the shutter is closed, the light beam is shielded by one of the light shielding portions 64. However, when the shutter plate 61 starts rotating, the light beam reaches the boundary between the light shielding portion 64 and the light passing portion 63, and irradiation starts. But the shutter plate 61 is 90
When rotated, the shutter is completely opened as shown in FIG. 2A, and all beams of light pass through the light passage section 63. Then, from this state, the shutter plate 61 is further moved 90 degrees.
When rotated, the shutter is closed as shown in FIG. 2B, and the light is shielded again by the light shielding unit 64. That is, when the shutter plate 61 rotates by 180 °, one cycle of shutter closing → shutter opening → shutter closing is completed,
In the meantime, the work is exposed. Such a shutter mechanism has an advantage that the integrated light amount on the irradiated surface can be kept constant during the period from the start of irradiation to the end of irradiation because the rotation directions of the two light-shielding portions 64 in one cycle are constant.

[0006]

However, recently, due to a demand for an improvement in throughput, for example, in the manufacture of a semiconductor device, the sensitivity of a resist applied to a work is increased, and the irradiance of a discharge lamp is increased to expose the work. Try to save time. And to shorten the exposure time,
The shutter mechanism needs to open and close at high speed. That is,
It is necessary to rotate the shutter plate at high speed and to stop it at a predetermined position quickly and accurately. For this purpose, it is necessary to reduce the rotational moment by making the shutter plate thinner and lighter.

[0007] When the irradiance of the discharge lamp is increased, when the shutter mechanism is closed, light having a high radiation intensity is irradiated to the shutter plate, which is a light shielding portion. Although the temperature of the shutter plate becomes high due to conversion into energy, if the shutter plate is made thinner and lighter, the shutter plate undergoes thermal deformation when used for a long time.

Further, the conventional shutter plate shown in FIG.
The shutter plate near the rotation axis has a small area and low strength because the light passage is formed by cutting out both sides of the shutter plate in a fan shape, so when the shutter is closed, the shutter plate rotates when the temperature of the light shielding unit increases. The temperature difference between the shutter plates near the axis increases, and the shutter plates deform to twist. Then, when the shutter plate is deformed, even if the shutter mechanism is closed, light may leak to the irradiation surface side and does not function as a shutter. If the deformation is significant, the shutter plate may be damaged.

[0009] Thermal deformation of the shutter plate can be prevented by, for example, attaching a reinforcing material to the shutter plate. In addition, it is conceivable to attach a radiation fin to increase the heat dissipation capacity and suppress a temperature rise. However, if reinforcing materials or heat radiation fins are attached to the shutter plate, the weight increases and the rotational moment increases, making it difficult to rotate the shutter plate at high speed and with high precision and quick stop. Means are needed. That is, this is contrary to the demand for thinner and lighter shutter plates. As described above, the conventional shutter plate is made of aluminum and is thin and lightweight, but no treatment has been performed to withstand thermal deformation due to radiant heat from a discharge lamp having recently increased irradiance. .

Accordingly, the present invention provides a light source which has a thin and lightweight shutter plate which can be opened and closed at a high speed, and which does not cause thermal deformation even when used for a long time to open and close a light beam of a strong irradiation intensity of a discharge lamp. An object is to provide a shutter mechanism of an irradiation device.

[0011]

In order to achieve the above object, according to the first aspect of the present invention, a fan-shaped notch is formed in a disc-shaped shutter plate material to form a light passage portion, and a non-notch portion is formed. In the shutter mechanism, which rotates the balance plate in a balanced load state around the rotation axis disposed at the center of the shutter plate to open and close the beam of the discharge lamp of the light irradiation device, the light incident on the light shielding unit The surface is mirror-finished and an infrared emitting film is formed on the back surface of the light incident surface. It is preferable that the rotation axis of the shutter plate is slightly inclined with respect to the optical axis of the light beam so that the light reflected by the light shielding portion does not enter the vicinity of the discharge lamp again.

Next, according to a second aspect of the present invention, a fan-shaped notch is formed in a disk-shaped shutter plate material to form a light passing portion,
In a shutter mechanism that opens and closes a beam of a discharge lamp of a light irradiation device using a shutter plate that is a non-notched portion as a light blocking portion, only one light passing portion is formed between a pair of light blocking portions, and the center of the shutter plate is formed. The shutter plate on the side opposite to the light passage section is shaped so that the center of gravity of the shutter plate coincides with the center of the shutter plate, and the shutter plate is placed in a balanced load state around the rotation axis arranged at the center of the shutter plate. Rock it.

According to a third aspect of the present invention, the light incident surface of the light shielding portion of the shutter plate according to the second aspect of the present invention is mirror-finished and an infrared radiation film is formed on the back surface of the light incident surface. Preferably, also in this case, the rotation axis of the shutter plate is slightly inclined with respect to the optical axis of the light beam so that the light reflected by the light shielding portion does not enter the vicinity of the discharge lamp again. Is preferred.

[0014]

Embodiments of the present invention will be specifically described below with reference to the drawings. The shape of the shutter plate used in the embodiment of the first aspect of the present invention is the same as that shown in FIG. That is, a thickness of 2 mm and an outer diameter of 710 mmφ
A disc-shaped aluminum plate is used as a material of the shutter plate 61, and both sides of the aluminum plate are cut out in a fan shape at an angle of 90 °, and the two symmetrical notches are formed as light-passing portions 63.
It is. The remaining aluminum plate, which is a non-cutout portion, is also a fan-shaped light shielding portion 64, and the two light shielding portions 64 are also symmetrical. For this reason, the area of the center of the shutter plate 61 is very small. A rotating shaft 62 is arranged at the center corresponding to the center of gravity of the shutter plate 61, and the shutter plate 61 smoothly rotates in a fixed direction about the rotating shaft 62 in a fixed direction by a driving unit and a braking unit (not shown). Then, it stops at a predetermined position.

The light incident surface of the light shielding portion 64 is subjected to mirror finishing, for example, high-intensity polishing such as electrolytic polishing, and a mirror surface 65 indicated by a dotted line in FIG. 3 is formed for convenience. On the other hand, on the back surface of the light incident surface of the light shielding portion 64, an infrared radiation film 66 also indicated by a dotted line for convenience is formed. The infrared radiation film 66 efficiently radiates the heat energy accumulated in the shutter plate 61 from the surface not irradiated with light and suppresses the temperature rise of the shutter plate 61. As a typical example, black electroless nickel plating is used. Although it can be mentioned, a black paint having heat resistance may be used.

As described above, since the mirror surface 65 is formed on the light incident surface of the light shielding portion 64, most of the incident light is reflected, and the heat energy stored in the shutter plate 61 is extremely small. Further, since the infrared radiation film 66 is formed on the back surface of the light incident surface of the light shielding portion 64, the heat energy accumulated in the shutter plate 61 is efficiently radiated from the surface not irradiated with light, and the temperature rise is suppressed. You.

For this reason, even if the area of the central portion of the shutter plate 61 on which the rotating shaft 62 is disposed is small and the strength is weak, it is possible to prevent thermal deformation at this portion. Further, since the cooling fins and the reinforcing material for preventing deformation are not attached, the rotational moment of the shutter plate 61 does not increase, so that the shutter plate 61 can be rotated at high speed and quickly stopped with high accuracy. , It is possible to cope with the reduction of the exposure time.

Here, when the light beam enters the light incident surface of the light shielding portion 64 at a right angle, the light reflected by the mirror surface 65 of the light shielding portion 64 returns to the optical axis of the light beam as it is, and is reflected by the condenser mirror and discharged. Since the light is condensed on the electrodes, bulbs, and base of the lamp, the temperature of the discharge lamp increases, which may adversely affect optical characteristics. For this reason, the rotation axis 62 of the shutter plate 61 is inclined, for example, by about 5 ° with respect to the optical axis of the beam of light, and as shown in FIG. It is better not to return.

Next, an embodiment of the present invention will be described. The material of the shutter plate 61 is 2 mm thick and 71 mm in outer diameter.
As shown in FIG. 4, one side of this aluminum plate is cut out in a fan shape at an angle of 90 ° to form a light passing portion 63, and a non-notched portion is formed as shown in FIG. These are the light shielding portions 64a and 64b. That is, the pair of light shielding portions 64
Only one light passing portion 63 is formed between a and 64b. The rotation shaft 62 is disposed at the midpoint of the upper and lower center lines L (the center of the shutter plate 61) of the shutter plate 61 shown in FIG.

When the shutter is closed, as shown in FIG. 5A, the beam of light is blocked by one of the light shielding portions 64a. When the shutter plate 61 rotates in the direction of the arrow, the beam of light starts to irradiate from above, and when the shutter plate 61 rotates 90 °, the shutter is fully opened as shown in FIG. All the light beams pass through the light passing section 63.
Then, when the shutter plate 61 is further rotated by 90 ° from this state, the shutter is closed as shown in FIG. 5C, and the light is shielded again by the other light shielding portion 64b. That is, when the shutter plate 61 rotates by 180 °, one cycle of shutter closing → shutter opening → shutter closing is completed, and the work is exposed during that time. Then, in the next cycle, the shutter plate 61 rotates in the opposite direction.
That is, the shutter plate 61 performs a swinging movement about the rotation axis 62. In such a shutter mechanism, since the rotation directions of the two light shielding portions 64a and 64b in one cycle are constant, from the start of irradiation to the end of irradiation. During the time, the integrated light amount on the irradiated surface can be made constant.

Here, in order for the shutter plate 61 to smoothly swing in a balanced load state, the center of the shutter plate 61 on which the rotating shaft 62 is disposed needs to coincide with the center of gravity of the shutter plate 61. For this reason, the shape of the shutter plate 61 on the side opposite to the light passing portion 63 is changed to the shutter plate 6.
The upper and lower center lines L are equal in the left and right areas, and the upper and lower centers are symmetrical. FIG. 4 is an example, and various shapes are possible. In any case, since there is only one light-passing portion 63 cut out in a fan shape, the shutter plate 61 near the rotation shaft 62 The area can be much larger than in the conventional example shown in FIG.

For this reason, even if the temperature of the shutter plate 61 rises, the area of the shutter plate 61 near the rotating shaft 62 is large and the strength is strong, so that thermal deformation of this portion can be prevented. Further, the weight of the shutter plate 61 is exactly the same as that of the conventional example shown in FIG. 2, and the rotating moment does not increase, so that the shutter plate 61 can be rotated at high speed and quickly stopped with high accuracy, and the exposure time can be reduced. can do.

Next, in the shutter plate 61, as described above, the light incident surfaces of the light shielding portions 64a and 64b are mirror-finished to form a mirror surface.
It is preferable to form an infrared radiation film on the back surface of the light incident surface of a, 64b. Thereby, the temperature rise of the shutter plate 61 can be suppressed efficiently, and the large effect of the large area and large strength of the shutter plate 61 near the rotation shaft 62 can provide a great effect in preventing thermal deformation. Can be. Also in this case, it is preferable that the rotation axis 62 of the shutter plate 61 is inclined with respect to the optical axis of the light beam so that the light reflected by the mirror surfaces of the light shielding portions 64a and 64b does not return to the optical axis of the light beam. .

[0024]

As described above, according to the present invention,
Even if it is used for a long time to open and close the light beam of the strong irradiation intensity of the discharge lamp, the light can be opened and closed at high speed without causing thermal deformation of the shutter plate and without increasing the rotational moment of the shutter plate. It can be a shutter mechanism of the device.

[Brief description of the drawings]

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

FIG. 2 is an explanatory view of a conventional example of a shutter plate.

FIG. 3 is an explanatory diagram of an embodiment of the first invention.

FIG. 4 is a plan view of an embodiment of the invention of claim 2;

FIG. 5 is an operation explanatory view of the embodiment of the second invention.

[Explanation of symbols]

 Reference Signs List 61 shutter plate 62 rotation axis 63 light passing part 64 light shielding part 65 mirror surface 66 infrared radiation film

Claims (4)

[Claims] 1. A disk-shaped shutter plate material having a fan-shaped notch formed as a light-passing portion, a non-notched shutter plate as a light-shielding portion, and a rotating shaft disposed at the center of the shutter plate. In a shutter mechanism that opens and closes the light beam of the discharge lamp of the light irradiation device by rotating in a balanced load state around the mirror, while performing mirror finishing on the light incident surface of the light shielding unit, an infrared emitting film is formed on the back surface of the light incident surface. A shutter mechanism of the light irradiation device, wherein the shutter mechanism is formed. 2. Opening and closing a light beam of a discharge lamp of a light irradiation device by forming a fan-shaped notch portion in a disk-shaped shutter plate material as a light passing portion and a shutter plate as a non-notched portion as a light shielding portion. In the shutter mechanism, only one light passing portion is formed between the pair of light shielding portions, and the shutter plate on the side opposite to the light passing portion with respect to the center of the shutter plate is located at the center of gravity of the shutter plate. A shutter mechanism for a light irradiation device, wherein the shutter mechanism has a shape that matches the center and swings a shutter plate about a rotation axis arranged at the center of the shutter plate. 3. The light irradiation device according to claim 2, wherein the light-incident surface of the light-shielding portion is mirror-finished and an infrared-emitting film is formed on the back surface of the light-incident surface. The shutter mechanism of the device. 4. The shutter mechanism of the light irradiation device according to claim 1, wherein a rotation axis of the shutter plate is inclined with respect to an optical axis of the light beam. .