JPH07235281A - D.c. discharge lamp, semiconductor exposure device using this discharge lamp, and projection device - Google Patents

Abstract

PURPOSE:To prevent the decrease in light collecting effect even when used in combination. with an optical system by satisfying the relation shown in a specific formula on lamp current, the distance between electrodes, body outer diameter of an anode, and radius of curvature of a curved surface. CONSTITUTION:An anode 11 positioned in a lower part and a cathode 12 positioned in an upper part are faced in a luminescent space within a bulb 10 of an extra-high pressure mercury lamp, and a specified amount of noble gas and mercury are sealed in the space. The cathode 12 is covered with a holding tube 17a through a molybdenum plate in a sealing part 15b, and the electrode side of a metal foil 13a is electrolytically polished. The anode 11 is formed with a body 11a, a straight taper part 11b continuing in a tip direction from the body 11a, a curved part 11c formed at the tip, and a lead rod 11d. When lamp current is IL A, the distance between electrodes is Lmm, the outer diameter of the body is Dmm, the radius of curvature of a curved surface 11c is Rmm, the formulas of 2 0.25<=4.1.IL/piD<2> <=0.45, and 0.5R<=D/L<=1.8R are satisfied. Damage at the tip of the anode in accordance with the elapse of lighting time is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct current discharge lamp, and more particularly to a direct current discharge lamp which requires a high voltage or high voltage pulse when starting the lamp, such as a short arc type discharge lamp used in combination with an optical system. The present invention relates to a projection device and a semiconductor exposure device using a discharge lamp.

[0002]

2. Description of the Related Art Conventional DC discharge lamps of this type have a pair of electrodes facing each other in a bulb forming a light emitting space and filled with a rare gas, mercury or a metal halide, xenon gas or the like. Utilizing features such as high efficiency and high color rendering,
Widely used in various fields. Among them, the so-called short arc type DC discharge lamp with a short arc length has a feature similar to a point light source in addition to the above features, so it can be used in combination with an optical system for semiconductor exposure, projection, projector use. It is used as a light source.

By the way, such a DC discharge lamp is disclosed in, for example, JP-A-60-57930. In this DC discharge lamp, a cone-shaped cathode and an anode having a flat tip and a tapered shape are arranged.

In the DC discharge lamp disclosed in Japanese Patent Laid-Open No. 50-28180, as shown in FIG. 7, the conical angle α of the tip of the anode 1 is 80 to 100 °, and the tip of the cathode 2 is The cone angle β of is set in the range of 60-80 °, and both poles are 0.1 mm.
It is rounded with the above radius of curvature.

Since such a DC discharge lamp is used in combination with an optical system, strict position adjustment is required at the time of lamp replacement and the replacement time is long. Therefore, it is desired to extend the life of the lamp. In addition, the stability of the optical output over a long period of time is also required from the viewpoint of application. For this reason, the above-mentioned ones are adopted in the conventional DC discharge lamp.

[0006]

However, it is difficult to extend the life of the conventional DC discharge lamp described above. This is because, as the lighting time elapses, the light collection efficiency when combined with an optical system decreases due to the increase in the distance between the electrodes, or the light output decreases due to the blackening of the inner surface of the bulb due to the scattering of electrode material and the blackness of the inner surface of the bulb As a result, the valve temperature rises and problems such as strain increase occur, resulting in a problem of a short life.

The present invention has been made in consideration of the above-mentioned circumstances, and it is possible to prevent a decrease in light output over a long period of time and to prevent a decrease in light collection efficiency even when used in combination with an optical system. An object of the present invention is to provide a DC discharge lamp, a projection apparatus using the discharge lamp, and a semiconductor exposure apparatus.

[0008]

In order to solve the above-mentioned problems, a direct current discharge lamp according to claim 1 of the present invention is a direct current discharge lamp in which a positive electrode and a negative electrode are arranged facing each other in a light emission space of a quartz glass bulb. In the discharge lamp, the anode has a body portion, a tapered portion continuous from the body portion in a tip direction, and a curved surface portion formed at the tip of the tapered portion, and the lamp current _IL (A),
Distance between electrodes L (mm), outer diameter of the body of the anode D (m
m), where R (mm) is the radius of curvature of the curved surface section,

[Formula 3] 0.25 ≦ 4 · I _L / πD ² ≦ 0.45

## EQU4 ## It is characterized in that the relationship of 0.5R≤D / L≤1.8R is satisfied.

The DC discharge lamp according to claim 2 is characterized in that the tapered portion of the anode is linear.

A DC discharge lamp according to a third aspect of the present invention is characterized in that the anode is arranged below and the cathode is arranged above.

The DC discharge lamp according to claim 4 is characterized in that the inter-electrode distance L is set in a range of 1 to 10 (mm).

The DC discharge lamp according to claim 5 is characterized in that the taper portion of the anode is formed to have a cone angle in the range of 60 to 120 °.

A semiconductor exposure apparatus according to a sixth aspect is characterized in that a semiconductor exposure apparatus main body and the DC discharge lamp according to any one of the first to fifth aspects are arranged in the semiconductor exposure apparatus main body.

A projection apparatus according to a seventh aspect comprises a projection apparatus main body,
The DC discharge lamp according to any one of claims 1 to 5 is arranged in the main body of the projection apparatus.

[0015]

In the first aspect of the present invention having the above structure, the anode has a body, a taper portion continuous from the body in a tip direction, and a curved surface portion formed at a tip of the taper portion, Lamp current I _L (A), inter-electrode distance L (mm), body outer diameter D (mm) of the anode, curvature radius R of the curved surface portion
(Mm),

[Formula 5] 0.25 ≦ 4 · I _L / πD ² ≦ 0.45

Since the relationship of 0.5R ≦ D / L ≦ 1.8R is satisfied, damage to the tip of the anode that occurs with the passage of lighting time can be prevented, and the distance between the electrodes can be increased and the bulb can be prevented. The scattering of black matter on the inner surface is also reduced,
As a result, the life of the lamp can be extended.

According to the present invention, by making the taper portion of the anode straight, the arc is stabilized and the local temperature rise at the tip of the anode can be avoided.

According to the third aspect of the present invention, by disposing the anode on the lower side and the cathode on the upper side, it is possible to make the temperature distribution in the valve uniform even if the temperature of the anode rises. The vapor pressure of mercury or metal halide enclosed in the inside can be maintained appropriately. As a result, a stable light output can be obtained.

As described in claim 4, the distance L between the electrodes is 1 to 10
It is desirable to set in the range of (mm).

According to a fifth aspect, the taper portion of the anode is 60
By forming the cone angle in the range of up to 120 °, the arc is stabilized, the temperature of the anode is made uniform, and a local temperature rise at the tip can be avoided.

The DC discharge lamp of the present invention is preferably arranged in a semiconductor exposure apparatus or a projection apparatus as claimed in claims 5 and 6.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view showing an ultra-high pressure mercury lamp which is an embodiment of a DC discharge lamp according to the present invention, FIG. 2 is an enlarged view showing an anode in FIG. 1, and FIG. 3 is an enlarged view showing a cathode in FIG. It is a figure.

In FIG. 1, the ultrahigh pressure mercury lamp has a bulb 10 made of quartz glass. In the bulb 10, an anode 11 located below and a cathode 12 located above oppose the emission space. The rare gas and mercury are enclosed in a predetermined amount inside.

The anode 11 and the cathode 12 are electrically connected to the caps 14a and 14b via the metal foils 13a and 13b, respectively, and the metal foil 13 is formed in the sealing portions 15a and 15b.
It is hermetically sealed on a and 13b.

The anode 11 is made of tungsten, and as shown in FIG. 2, a getter 16 made of tantalum and having a length of 9 mm and a thickness of 0.1 mm is integrally formed. The sealing portion 15a has a quartz length of 8 mm. The holding tube 17a made of aluminum is attached via a molybdenum plate. The length of the metal foil 13a is 45 mm, the width is 6 mm, and the thickness is 0.026 mm.
Made of molybdenum, and the electrode side is electrolytically polished.
37 mm in length and 7 m in width between the metal foils 13a, 13a
A separator 18a made of quartz and having a thickness of 1.5 mm and a thickness of 1.5 mm is sandwiched.

As shown in FIG. 3, the cathode 12 has a sealing portion 15b to which a quartz holding tube 17b having a length of 8 mm is attached via a molybdenum plate, and a metal foil 13b has a length of 28 mm. Width 5 mm, thickness 0.
It is made of molybdenum of 026 mm, and the electrode side is electrolytically polished. 21m in length between the metal foils 13b, 13b
A separator 18b made of quartz and having a size of m, a width of 7 mm, and a thickness of 2.0 mm is sandwiched.

As shown in FIG. 4, the anode 11 has a body portion 11a, a linear taper portion 11b continuous from the body portion 11a in the tip direction, and a curved surface portion 11c formed at the tip of the taper portion 11b. , The lead rod 11d, and the curved surface portion 11c has a radius of curvature R (mm).
The anode 11 and the cathode 12 are arranged so as to face each other with a distance L (mm) between the electrodes.

Next, based on the above-mentioned embodiment, the following 40 ultra-high pressure mercury lamps were manufactured and a lighting life test was conducted.

Lamp current I _L (A): 20 A (50 V,
1000 W), distance L between electrodes (mm): 3 mm, outer diameter D of the body of the anode D (mm): 7, 7.5, 8, 8.5
9, 9.5, 10.0, 10.5 (mm), taper angle θ of anode: 90 °, radius of curvature R (mm) of curved surface part of anode: 2, 2.5, 3.
0, 3.5, 4.0, the 40 lamps were continuously turned on for 1500 hours, and the results shown in Table 1 were obtained.

[0030]

[Table 1]

From the above results, when the judgment was made on the basis of a practical exposure surface illuminance maintenance ratio of 70% in combination with the arc stability optical system after lighting for 1500 hours, the outer diameter D of the body portion was 7.
5 to 10.0 (mm) and the radius of curvature R is 2.5 to
If it is between 3.5 (mm), that is,

[Formula 7] 0.25 ≦ 4 · I _L / πD ² ≦ 0.45

## EQU8 ## If the relationship of 0.5R.ltoreq.D / L.ltoreq.1.8R is satisfied, it has been found that there is practically no problem.

Next, the operation of this embodiment will be described.

The anode 11 includes a body 11a and the body 11a.
Has a tapered portion 11b continuous from the front to the tip end and a curved surface portion 11c formed at the tip of the tapered portion 11b. The lamp current I _L (A), the inter-electrode distance L (mm), Diameter D (mm), radius of curvature R (m of curved surface portion 11c
m)

[Formula 9] 0.25 ≦ 4 · I _L / πD ² ≦ 0.45

Since the relation of 0.5R ≦ D / L ≦ 1.8R is satisfied, damage to the tip of the anode that occurs with the passage of lighting time can be prevented, the distance between the electrodes can be increased, and the bulb can be prevented. The scattering of black matter on the inner surface is also reduced,
As a result, the life of the lamp can be extended.

Further, by making the taper portion 11b of the anode 11 linear, the arc is stabilized and the temperature rise at the tip can be avoided.

Further, in this embodiment, the anode 11 is arranged at the lower side and the cathode 12 is arranged at the upper side, so that the temperature distribution in the bulb 10 is made uniform even if the temperature of the anode 11 rises. Therefore, the vapor pressure of the mercury enclosed in the bulb 10 can be properly maintained. As a result, a stable light output can be obtained.

In the above lighting life test, the distance L between the electrodes
Was set to 3 (mm), but not limited to this, the distance between electrodes L
The same effect can be obtained by setting 1 to 10 (mm).

In the above lighting life test, the anode 1
Although the angle θ of the tapered portion 11b of No. 1 is set to 90 °, the present invention is not limited to this, and if the conical angle is formed in the range of 60 to 120 °, the arc is stabilized and the temperature is made uniform, so that the anode 1
It is possible to avoid a local temperature rise at the tip of No. 1.
Here, if the angle θ of the tapered portion 11b is less than 60 °, the temperature at the tip of the anode 11 rises abnormally and deteriorates in a short time, while if it exceeds 120 °, the arc is unstable and The temperature becomes uneven.

Lamp current I _L : 20 A (25 V,
500 W), the distance L between electrodes: 3.5 (mm), the outer diameter D of the body portion of the anode 11 and the radius of curvature R of the curved surface portion 11c of the anode 11 were varied in the same manner as in the above-described embodiment, and 1000 hours When the lighting test of No. 2 was carried out, it was found to be satisfactory if the above-mentioned Formulas 1 and 2 were satisfied.

Further, the present invention is not limited to the above-mentioned embodiment, but it is needless to say that the present invention can be applied to a metal halide lamp for direct current lighting in which a metal halide is enclosed.

FIG. 5 shows an example in which an ultra-high pressure mercury lamp, which is an embodiment of the DC discharge lamp according to the present invention, is applied to a semiconductor exposure apparatus. In FIG. 5, the light emitted from the ultra-high pressure mercury lamp 20 is reflected by the elliptical mirror 21 and the reflection mirror 22, respectively, is condensed by the condenser lens 23, and then passes through the reflection mirror 24 and the condenser lens 25 to be photoresist. Then, it is exposed on the wafer 28 through the reduction projection lens 27.

FIG. 6 shows an example in which a xenon lamp, which is another embodiment of the DC discharge lamp according to the present invention, is applied to a projection device. In FIG. 6, the light emitted from the xenon lamp 30 is reflected by the elliptical mirror 31 and is reflected by the lenses 32a, 3a.
2b, and the condensed light is passed through the film 33 as parallel light by the lenses 32a and 32b, and then expanded through a magnifying lens 34 to project an image of the film 33 on a screen 35.

Therefore, if the ultra-high pressure mercury lamp of the above-mentioned embodiment is applied to a semiconductor exposure apparatus and the xenon lamp is applied to a projection apparatus, a decrease in illuminance on the irradiation surface is small and a stable arc state can be obtained.

[0043]

As described above, according to the first aspect of the DC discharge lamp of the present invention, the anode has the body portion, the taper portion continuous from the body portion in the tip direction, and the tip of the taper portion. A curved surface portion formed on the lamp current I _L (A), an inter-electrode distance L (mm), an outer diameter D (mm) of the body of the anode,
When the radius of curvature R (mm) of the curved surface portion is

[Formula 11] 0.25 ≦ 4 · I _L / πD ² ≦ 0.45

Since the relationship of 0.5R ≦ D / L ≦ 1.8R is satisfied, damage to the anode tip portion that occurs with the passage of lighting time can be prevented, and the distance between electrodes and the bulb can be increased. The splash of black matter on the inner surface is also reduced. As a result, a high light output can be maintained for a long period of time, and the lamp life can be extended.

According to the second aspect, by making the taper portion of the anode linear, the arc is stabilized and a local temperature rise at the tip of the anode can be avoided.

According to the third aspect, by disposing the anode in the lower part and the cathode in the upper part, it is possible to make the temperature distribution in the valve uniform even if the temperature of the anode rises. The vapor pressure of mercury or metal halide enclosed in the bulb can be maintained appropriately. As a result, a stable light output can be obtained.

According to claim 4, the distance L between the electrodes is 1 to 1
Even if it is set in the range of 0 (mm), the same effect as in claim 1 can be obtained.

According to the fifth aspect, the taper portion of the anode is 60
By forming the cone angle in the range of up to 120 °, the arc becomes stable and the temperature becomes uniform, and the temperature rise at the tip can be avoided.

Furthermore, when the DC discharge lamp of the present invention is applied to a semiconductor exposure apparatus or a projection apparatus as in claim 6 or claim 7, a decrease in illuminance on the irradiation surface is small and a stable arc state is obtained. To be

[Brief description of drawings]

FIG. 1 is a front view showing an ultra-high pressure mercury lamp which is an embodiment of a DC discharge lamp according to the present invention.

FIG. 2 is an enlarged view showing an anode of the above embodiment.

FIG. 3 is an enlarged view showing the cathode of the above embodiment.

FIG. 4 is an enlarged view showing an anode and a cathode of the above embodiment.

FIG. 5 is a schematic view showing a semiconductor exposure apparatus to which an ultrahigh pressure mercury lamp according to an embodiment is applied.

FIG. 6 is a schematic view showing a projection device to which a xenon lamp of another embodiment of the DC discharge lamp according to the present invention is applied.

FIG. 7 is an enlarged view showing an anode and a cathode of a short arc discharge lamp which is a conventional DC discharge lamp.

[Explanation of symbols]

 10 Valve 11 Anode 11a Body 11b Tapered part 11c Curved part 11d Lead rod 12 Cathode 13a, 13b Metal foil 14a, 14b Base 15a, 15b Sealing part

Claims (7)

[Claims] 1. A direct current discharge lamp in which an anode and a cathode are arranged to face each other in a light emission space of a quartz glass bulb, wherein the anode has a body portion, a taper portion continuous from the body portion in a tip direction, and the taper portion. The lamp current I _L (A), the inter-electrode distance L (mm), the outer diameter D (mm) of the body of the anode, and the radius of curvature R (m of the curved surface portion.
m), the following relationship is satisfied: 0.25 ≦ 4 · I _L / πD ² ≦ 0.45 ## EQU2 ## 0.5R ≦ D / L ≦ 1.8R DC discharge lamp. 2. The DC discharge lamp according to claim 1, wherein the tapered portion of the anode has a linear shape. 3. The anode is disposed below, and
The cathode is arranged above.
Alternatively, the DC discharge lamp according to item 2. 4. The distance L between the electrodes is 1 to 10 (mm).
The direct current discharge lamp according to claim 1, wherein the direct current discharge lamp is set in the range. 5. The taper portion of the anode is 60 to 120 °.
The DC discharge lamp according to claim 1 or 2, wherein the DC discharge lamp is formed with a cone angle in the range. 6. A semiconductor exposure apparatus main body, and the semiconductor exposure apparatus main body, wherein the DC discharge lamp according to any one of claims 1 to 5 is arranged. 7. A projection apparatus main body, and the projection apparatus main body, wherein the DC discharge lamp according to claim 1 is arranged in the projection apparatus main body.