JPH1097973A - Ultraviolet-ray irradiation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultraviolet-ray irradiation device which can be operated easily and can easily perform precise illuminance adjustment. SOLUTION: A discharge lamp 1a is positioned so that the maximum luminance part can come to the position of the first focal point of an elliptic light condensing mirror 1b. The second focal point of the mirror 1b is positioned to the light emitting section 2' of a lamp house and the light from the lamp 1a is condensed to the second focal point. The section 2' is provided with an illuminance adjusting mechanism 20 which moves the incident end 3a of a light guiding fiber 3 in the direction of the optical axis and the illuminance can be adjusted by adjusting the distance between the incident end 3a of the fiber 3 and the second focal point. Since the illuminance is adjusted by moving the incident end 3a of the fiber 3, the illuminance variation becomes slower at the time of adjusting the illuminance and the illuminance is monotonously reduced when the incident end 3a is moved farther from the second focal point. Therefore, the illuminance can be adjusted precisely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet irradiation apparatus used for exposing and spot curing a peripheral portion of a semiconductor wafer, and more particularly to an ultraviolet irradiation apparatus provided with a mechanism for adjusting ultraviolet illuminance. .

[0002]

2. Description of the Related Art In a manufacturing process of various electronic devices, an ultraviolet irradiation apparatus is used for exposing a resist applied to various substrates to an exposure process. In the above-described exposure processing, it is necessary to make adjustments so that the amount of exposure applied to the resist is always constant. For example, in the case of a positive photoresist, the portion irradiated with the exposure light changes into a substance soluble in the developing solution by a photochemical reaction. And remains on the substrate surface without being dissolved.

The exposure amount is defined by illuminance × time, and in order to make the exposure amount constant, it is necessary to adjust the illuminance or the exposure time by changing it. If the illuminance is large, the exposure time is short and the throughput is short, but if the illuminance is too large, the photochemical reaction occurs rapidly, so that gas (nitrogen) generated during the reaction becomes bubbles in the resist, and in some cases, bursts, The popped resist becomes dust and causes a defect.
On the other hand, if the exposure time is lengthened, a sufficient exposure amount can be obtained even with a small illuminance, but the throughput increases.
That is, there is a certain optimum condition range in the relationship between the illuminance and the exposure time.

At present, the following method is employed in order to make the above exposure amount (= illuminance × exposure time) constant. (a) Measure the illuminance of the exposure light emitted from the exposure light emitting unit at regular time intervals. If the change in illuminance is within a certain range, exposure is performed by changing the exposure time to keep the exposure amount constant. That is, when the illuminance decreases by several percent, the exposure time is lengthened by the corresponding amount to make the exposure amount constant. (b) When the illuminance falls below the predetermined range, the illuminance is manually adjusted to increase the illuminance as described later.

The reason why both the exposure time and the illuminance are adjusted and one is not fixed is as follows. The lamp used as the light source of the ultraviolet irradiation device is usually a discharge lamp, and the illuminance gradually changes (decreases) when it is turned on. It is cumbersome to manually adjust the constantly changing illuminance and keep it constant. The illuminance of the lamp changes because the electrodes are worn and the shape of the arc changes, and the substance used for the electrodes adheres to the inner wall of the glass that forms the lamp envelope, causing the glass to blacken. This is because the light transmittance is reduced.

If only the exposure time is changed, it becomes very difficult to manage the processing capability of the apparatus, especially when there are a plurality of the same exposure apparatuses. That is, if the illuminances of the lamps of the respective exposure apparatuses are largely different, the exposure time of each apparatus must be greatly changed, and accordingly, the throughput between the apparatuses will be different. For this reason, operation management of a plurality of devices becomes difficult. As described above, in order to keep the exposure amount constant, it is necessary to adjust the illuminance of the light applied to the object to be processed. For this reason, conventionally, the following adjustment mechanism is provided in the ultraviolet irradiation apparatus. Had been.

FIG. 6 is a diagram showing a configuration of a conventional ultraviolet irradiation apparatus, and FIG. 6 shows a configuration of an ultraviolet irradiation apparatus for exposing a peripheral portion of a semiconductor wafer. In the figure,
Reference numeral 1 denotes a lamp house.
The light emitted from the lamp 1a is condensed by the elliptical converging mirror 1b, reflected by the mirror 1c, and emitted from the lamp house emission unit 2 when the shutter 1d is open. One end of the lamp 1a is attached to a lamp position adjusting mechanism 1f, and the light-emitting portion of the lamp 1a has X, Y, and Z directions near the first focal point of the elliptical converging mirror 1b (X is the horizontal direction in FIG. (Z is the vertical direction).

The second focal point of the elliptical converging mirror 1b is located in the vicinity of the lamp house emission part 2, and is arranged such that the second focal point coincides with the center of the incident end 3a of the light guide fiber 3. ing. Therefore, the light from the lamp 1 a is collected at the second focal point, and is guided to the exposure light emitting unit 4 via the light guide fiber 3. The exposure light guided to the exposure light emitting unit 4 via the light guide fiber 3 is emitted from the exposure light emitting unit 4 and irradiates the peripheral portion of the wafer W coated with the photoresist Ph.

The lamp position adjusting mechanism 1f has a handle 1g.
The position of the lamp 1a with respect to the elliptical focusing mirror 1b can be adjusted by rotating the handle 1g. The light guide fiber 3 is adjusted by adjusting the position of the lamp 1a by the lamp position adjusting mechanism 1f.
The amount of light condensed at the entrance end 3a of the
The amount of light emitted from the exposure light emitting section 4 can be changed.

In the above-mentioned ultraviolet irradiation device, the illuminance is adjusted as follows. (1) Illuminance adjustment when a new lamp is installed (when replacing the lamp). Attach a new lamp 1a, turn on the lamp 1a,
The shutter 1d is opened, and the illuminance of the exposure light emitted from the exposure light emitting unit 4 is measured. So that the illuminance is the maximum value
The lamp 1a is moved to X, Y, Z by the lamp position adjusting mechanism 1f.
Move in the direction. The position where the illuminance is maximum is the center of the incident end 3a of the light guide fiber 3, that is, the position where the light is focused on the second focal point of the elliptical focusing mirror, that is, the light emitting portion A of the lamp 1a.
Is the case where the portion with the maximum luminance at is located at the first focal point of the elliptical focusing mirror 1b. Next, the lamp 1a is moved only in the Z direction by the lamp position adjusting mechanism 1f to lower the illuminance so that the illuminance becomes a predetermined value. Lamp 1a to Z
The light-emitting portion A of the lamp 1a is shifted from the first focal point of the elliptical converging mirror 1b by the movement in the direction, the light is not collected at the second focal point, and the light incident from the incident end 3a of the light guide fiber 3 is changed. The amount is smaller. The above-mentioned predetermined value is smaller than the maximum illuminance, is equal to or less than the illuminance causing foaming of the photoresist Ph on the wafer W and the like, and is a value obtained by an experiment in advance so that the exposure time is not too long.

(2) When the illuminance drops below a predetermined value. The lamp 1a is moved in the Z direction by the lamp position adjusting mechanism 1f, and the light emitting portion of the lamp 1a is moved to the first position of the elliptical focusing mirror 1b.
Increase the illuminance closer to the focal point and return the illuminance to a predetermined value. When the light emitting portion A of the lamp 1a approaches the first focal point of the elliptical focusing mirror 1b, light is focused at the second focal point, and the amount of light incident from the incident end 3a of the light guide fiber 3 is large. Become. Until the illuminance of the lamp 1a is remarkably reduced and the light emitting portion A of the lamp 1a reaches the first focal point of the elliptical converging mirror 1b, it does not reach a predetermined value, or the lamp 1a as described above until the lamp reaches its guaranteed life. Adjust the position and adjust the illuminance.

[0012]

In the ultraviolet irradiation apparatus shown in FIG. 6, the illuminance change when the lamp 1a is moved in the Z direction is as shown in FIG. FIG. 7 shows that the point indicating the maximum illuminance (that is, when the brightest part of the light-emitting part A of the lamp 1a, which is the brightest part at the first focal point of the elliptical converging mirror 1b) is 0, and the handle 1g is determined from that position. Is operated to move the lamp 1a in the upward direction in the Z direction so that the lamp 1a
Is a plot of the change in illuminance with respect to the maximum illuminance when the light emitting portion A is shifted from the first focal point to the elliptical converging mirror 1b side.

As shown in FIG. 1, the position of the lamp 1a is
When moved in the direction, the illuminance does not change uniformly,
A peak occurs when a moves approximately 1.3 mm. This is because, as shown in FIG. 8, the luminance distribution of the light emitting portion A of the lamp 1a is not uniform, and there are two luminance peaks (F1 in FIG. 8).
a, F1b), which is considered to appear in the illuminance change as it is when the lamp 1a is moved. Also, as is clear from FIG. 7, the position of the lamp 1a is set at 1.
When the lamp 1a is moved by 7 mm, the illuminance changes by 50%. On average, when the lamp 1a is moved by 0.17 mm, the illuminance changes by 5%. For a new lamp, the maximum illuminance is usually about 2500 m
Since it is at least W / cm ² , the illuminance changes by 125 mW / cm ² by moving the lamp 1a by 0.17 mm.

As described above, in the conventional ultraviolet irradiation apparatus, the illuminance change when the position of the lamp 1a is moved is not uniform, and the illuminance greatly changes only by slightly moving the lamp 1a. However, there is a problem that it is difficult to adjust the illuminance and the adjustment requires skill. In addition, since the illuminance greatly changes only by slightly moving the position of the lamp 1a, it is necessary to provide a lamp position adjusting mechanism capable of adjusting the lamp position with high accuracy, and there is a problem that the apparatus cost is increased. Was.

Further, since the lamp position adjusting mechanism 1f is provided in the lamp house 3, the light shielding cover of the lamp house 3 must be opened in order to adjust the illuminance, and the illuminance of the lamp is reduced. When illuminance adjustment needs to be performed frequently, there is a problem that it takes time and effort. Although the illuminance can be changed by changing the power supplied to the lamp 1a, it is possible to change the illuminance only by changing the power.
%, And the lighting performance of the lamp when the illuminance is reduced is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to enable easy operation and fine adjustment of illuminance. An object of the present invention is to provide an ultraviolet irradiation device that can reduce costs.

[0017]

In order to solve the above-mentioned problems, in the present invention, instead of providing a conventional lamp position adjusting mechanism, the maximum luminance of the light emitting portion of the discharge lamp is provided at the first focal position of the elliptical condenser mirror. The discharge lamp is installed so that the portion of the light guide fiber is located, the position of the incident end of the light guide fiber is moved, and the distance between the position where light is condensed by the elliptical converging mirror and the incident end is adjusted. Thereby, the illuminance is adjusted. In the present invention, since the above configuration is adopted, the illuminance change at the time of the illuminance adjustment is gradual, and fine adjustment is possible. Further, when the illuminance is changed, the illuminance monotonously decreases, and the peak as shown in FIG. 7 does not occur, so that the adjustment becomes easy. Further, since the illuminance can be adjusted without opening the light shielding cover of the lamp house, the operation can be simplified.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a configuration of an ultraviolet irradiation device according to an embodiment of the present invention. In this embodiment, an ultraviolet irradiation apparatus in the above-described wafer peripheral exposure apparatus will be described. However, the present invention can be used as an ultraviolet irradiation apparatus for spot-irradiating ultraviolet light, such as spot cure, in addition to the wafer peripheral exposure apparatus. . 6, the same components as those shown in FIG. 6 are denoted by the same reference numerals, 1 is a lamp house, 1a is a lamp, 1b is an elliptical condenser mirror, 1c is a mirror, and 1d is a shutter. In this embodiment, the lamp 1a has a light-emitting portion A whose elliptical converging mirror 1
It is fixedly attached by the lamp fixing holder 1h so as to be located at the first focal point b and does not move.

Reference numeral 2 'denotes a lamp house emitting portion. The lamp house emitting portion 2' is positioned so that its center coincides with the second focal point of the elliptical converging mirror 1b. The illuminance adjusting mechanism 20 for adjusting the illuminance by moving the position of the incident end of the light guide fiber 3 is provided at 2 '. Then, the light incident on the light guide fiber 3 is guided to the exposure light emitting unit 4 via the light guide fiber 3,
The light is emitted from the exposure light emitting unit 4 and is irradiated to the peripheral portion of the wafer W coated with the photoresist Ph.

FIGS. 2 and 3 are views showing the configuration of the illuminance adjusting mechanism 20 of the lamp house emitting section 2 'described above. FIG. 2 is a sectional view after the assembly, and FIG. 3 is an exploded view.
2 and 3, reference numeral 21 denotes a first cylinder,
1 is attached to the outer wall of the lamp house 1 by a flange 21a. Reference numeral 22 denotes a second cylinder, and the second cylinder 22 is inserted into the first cylinder 21 as shown in FIG.
An annular retaining groove 22a is provided on the outer periphery of the second cylinder 22. After inserting the second cylinder 22 into the first cylinder 21, a retaining pin 21b is attached to the first cylinder 21. And the retaining pin 21b is inserted into the retaining groove 22.
a, the second cylinder 22 is rotatably attached to the first cylinder 21.

Reference numeral 23 denotes a third cylinder.
Is inserted into the assembly of the first and second cylinders 21 and 22 as shown in FIG. A screw groove 23 a is provided on the outer periphery of the third cylinder 23, and the screw groove 23 a engages with a guide pin 22 b attached to the second cylinder 22.
The third cylinder 23 is provided with a guide groove 23b in an axial direction outside the third cylinder 23, and a guide pin 21c attached to the first cylinder 21 is engaged with the guide groove 23b. For this reason, the third cylinder 23 does not rotate with respect to the first cylinder 21, but is attached so as to be movable in the direction of the arrow in FIG.

Further, the light guide fiber 3 is inserted into the third cylinder 23 as shown in FIG. 3 and fixed with a set screw (not shown). After assembling the lamp house emission part 2 ′ as shown in FIG. 2, when the second cylinder 22 is rotated,
The third cylinder 23 moves in the direction indicated by the arrow in the figure, and at the same time, the position of the incident end 3a of the light guide fiber 3 moves. That is, the guide pin 22b attached to the second cylinder 22 is engaged with the screw groove 23a provided in the third cylinder 23, and the third cylinder 23 is connected to the first cylinder 21 by the guide pin 21c. When the second cylinder 22 is rotated, the third cylinder 2 is not rotated.
The third screw groove 23a is guided by the guide pin 22b,
Of the light guide fiber 3 fixed to the third cylinder 23 also moves in the direction of the arrow.

The ultraviolet irradiating apparatus of the present embodiment has the above-described configuration, and the illuminance is adjusted by changing the position of the incident end 3a of the light guide fiber 3 by the illuminance adjusting mechanism 20 at the time of lamp replacement or illuminance adjustment. Can be adjusted. That is, in FIG. 1, the light from the lamp 1a is:
Since it is always focused on the second focal point of the elliptical focusing mirror 1b,
When the position of the incident end 3a of the light guide fiber 3 is closer to the second focal point, the converged light is incident on the incident end 3a and the illuminance of the light emitted from the exposure / emission unit 4 is increased. If the position of the incident end 3a of the optical fiber 3 is far from the second focal point, the diffused light enters the incident end 3a, so that the illuminance is reduced. The illuminance is maximum when the incident end 3a of the light guide fiber 3 is at the second focal point.

FIG. 4 shows the illuminance adjusting mechanism 2 in this embodiment.
FIG. 7 is a diagram showing a change in illuminance when the position of the incident end 3a of the light guide fiber 3 is changed by 0. FIG. 4 shows that the point indicating the maximum illuminance (that is, when the incident end 3a is at the second focal point of the elliptical converging mirror 1b) is 0, and the incident end 3a is moved from the second focal point to the opposite side of the lamp house 3 from that position. It is a plot of the change in illuminance with respect to the maximum illuminance when shifted. As shown in the figure, when the position of the incident end 3a of the light guide fiber 3 is moved by about 30 mm from the maximum illuminance point, the illuminance becomes 50% of the maximum illuminance.

In this embodiment, when the second cylinder 22 of the illuminance adjusting mechanism 20 is rotated once, the position of the incident end 3a of the light guide fiber 3 moves by 5 mm.
When is rotated six times, the illuminance becomes 50% of the maximum illuminance. Therefore, on average, the illuminance change per rotation of the second cylinder 22 is about 7%. Therefore, the illuminance change when the illuminance adjustment mechanism is operated is not abrupt as in the conventional device, and fine illuminance adjustment is possible.

As is apparent from FIG. 4, when the illuminance adjusting mechanism is operated, the illuminance decreases monotonously, and the peak of the illuminance as shown in FIG. 7 does not appear. Easy. This is for the following reason. FIG. 5 is a diagram showing a change in illuminance on the optical axis when the point F1a having the maximum luminance shown in FIG. 8 is located on the first focal point F1 of the elliptical condenser mirror 1b. Light emitted from the point F1a having the maximum luminance is collected at the position of the second focal point F2. On the other hand, light emitted from positions other than the first focal point F1 on the optical axis does not converge on the optical axis as shown by the broken line in FIG.

That is, in this embodiment, the lamp 1
a point F1a having the maximum luminance of the first focal point F of the elliptical focusing mirror 1b.
1 and the second peak F1b of the luminance distribution of the lamp 1a is shifted from the position of the first focal point F1, so that the second peak F1b is blurred at the position of the incident end 3a of the light guide fiber 3. This is because the effect is reduced. In the ultraviolet irradiation apparatus of this embodiment, the adjustment range of the illuminance is 50%, which is narrower than the conventional one. However, the adjustment range of the illuminance of the ultraviolet irradiation apparatus is usually 50%.
It is sufficiently practical because there are some degrees. If the moving distance of the light guide fiber is increased, the adjustment range can be 50% or more.

[0028]

As described above, according to the present invention, since the position of the incident end of the light guide fiber is moved to adjust the illuminance, the following effects can be obtained. (1) At the time of adjusting the illuminance, the change in the illuminance becomes gradual with respect to the distance of moving the adjustment mechanism, so that the illuminance can be finely adjusted. Moreover, since the illuminance can be adjusted without performing the positioning of the lamp position with high accuracy as in the related art, the cost of the illuminance adjustment mechanism can be reduced. (2) When the adjustment mechanism is moved, the illuminance change due to the luminance distribution of the light emitting portion of the lamp hardly appears, so that the adjustment is facilitated. (3) The illuminance can be adjusted without opening the light shielding cover of the lamp house, and the illuminance can be easily adjusted.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of an ultraviolet irradiation apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of an illuminance adjustment mechanism according to the embodiment of the present invention.

FIG. 3 is an exploded view of an illuminance adjustment mechanism according to the embodiment of the present invention.

FIG. 4 is a diagram showing a change in illuminance by the illuminance adjustment mechanism according to the embodiment of the present invention.

FIG. 5 is a diagram illustrating a change in illuminance on the optical axis when a point of maximum luminance of a light emitting unit of the lamp is positioned at a first focus;

FIG. 6 is a diagram showing a configuration of a conventional ultraviolet irradiation device.

FIG. 7 is a diagram showing a change in illuminance by a conventional illuminance adjustment mechanism.

FIG. 8 is a diagram showing a luminance distribution of a light emitting portion of the lamp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lamp house 1a Lamp 1b Elliptic converging mirror 1c Mirror 1d Shutter 1h Lamp fixing holder 2 'Lamp house emission part 3 Light guide fiber 4 Exposure light emission part 20 Illuminance adjustment mechanism 21 First cylinder 21a Flange 21b Retaining pin 21c Guide Pin 22 Second cylinder 22a Retaining groove 22b Guide pin 23 Third cylinder 23a Screw groove 23b Guide groove

Claims (1)

[Claims] 1. A short arc discharge lamp for emitting light including ultraviolet light, an elliptical condenser for condensing light emitted from the discharge lamp, and a light condensed by the elliptical condenser. Is incident from the incident end and emits the light from the exit end. An ultraviolet irradiation device comprising a light-guiding fiber, comprising: The discharge lamp is installed so that the position is located, the position of the incident end of the light guide fiber is moved, and the distance between the position where light is condensed by the elliptical converging mirror and the incident end is adjusted. An ultraviolet irradiation apparatus, comprising: