JP5180854B2 - Light source device and exposure apparatus provided with the light source device - Google Patents

Description

  The present invention relates to a light source device for exposure of a semiconductor, a liquid crystal substrate or a color filter, a light source device used for a backlight of an image projection apparatus such as a projector, and an exposure apparatus including the light source device.

  In recent years, for the exposure of semiconductors, liquid crystal substrates, or color filters, an ultraviolet light source having a large input power is used to shorten the processing time and collective exposure to a large-area workpiece. Further, in the field of image projection apparatuses such as projectors, it is required to increase the screen brightness. In connection with this, the light source of the said use is calculated | required to radiate | emit light with higher brightness | luminance. However, if the input power to the lamp is simply increased, the load on the discharge electrode arranged inside the lamp increases, and the vaporization from the electrode causes the lamp to become darker and shorter. There was a problem that the life would occur.

  In order to solve such problems, various proposals have been made. For example, the light source device of Patent Document 1 has a chamber in which a discharge medium is enclosed, and a laser oscillator for irradiating a continuous or pulsed laser beam to the discharge medium enclosed in the chamber. A light source device is disclosed. According to the light source device of this document, plasma is heated to a high temperature state by a laser beam, and it is expected that high brightness light can be obtained from the plasma in a high temperature state.

  However, the light source device of the same document has a problem that the use efficiency of the laser beam is low because a part of the laser beam emitted toward the chamber does not contribute to the generation of plasma.

US2007 / 0228288 A1

  An object of the present invention is to improve the utilization efficiency of laser light by reusing the laser light emitted toward the lamp.

The light source device of the present invention has high utilization efficiency of laser light by providing means for reusing the laser light transmitted through the lamp. That is, the light source device of the present invention has solved the above problems as follows.
(1)
A lamp enclosing a discharge medium;
A concave reflecting mirror having a concave reflecting surface for reflecting light emitted from the lamp;
A laser oscillator that emits laser light toward the lamp;
A polarization beam splitter disposed in the optical path of the laser light output from the laser oscillator, reflecting S-polarized laser light and transmitting P-polarized laser light;
A polarization rotation element that changes the polarization direction of linearly polarized light that passes through the lamp and exits through the concave reflecting mirror;
An optical element that reflects the linearly polarized light so that linearly polarized light that has passed through the lamp and exited through the concave reflecting mirror is incident on the polarization rotation element and the polarization beam splitter in this order.
(2)
In (1), the lamp includes a light emitting portion in which a pair of electrodes are arranged to face each other, and a rod-shaped sealing portion that extends outward in the tube axis direction continuously at both ends of the light emitting portion. The lamp and the concave reflecting mirror are arranged such that the optical axis of the concave reflecting mirror and the tube axis of the lamp are aligned.
(3)
In (1), the polarization rotation element is a λ / 2 plate.
(4)
In (1), the polarization rotation element is a λ / 4 plate.
(5)
In said (1), the said laser oscillator injects a laser beam from the light emission exit side of the said concave reflective mirror toward the reflective surface of the said concave reflective mirror.
(6)
An exposure apparatus including the light source device according to any one of (1) to (5), wherein light from the lamp is reflected on an optical path of the lamp emitted from the light exit port of the concave reflecting mirror to While changing the optical path of the light, a wavelength selective reflection mirror that transmits the laser light emitted from the laser oscillator is provided.

  In the light source device of the present invention, a lamp in which a discharge medium is enclosed, a concave reflecting mirror that reflects light emitted from the lamp, a laser oscillator that emits laser light toward the lamp, a polarization beam splitter, and polarization rotation By including an element and an optical system that reflects the laser light transmitted through the lamp so as to enter the polarization rotation element and the polarization beam splitter in this order, the laser light transmitted through the lamp can be reused. . Therefore, the utilization efficiency of laser light is improved.

1 shows a schematic configuration of a light source device according to a first embodiment of the present invention. The outline of the structure of the lamp | ramp used for the light source device of FIG. 1 is shown. The optical path of a laser beam is shown in the light source device of FIG. The outline of the other structural example regarding 1st Embodiment of the light source device of this invention is shown. The optical path of a laser beam is shown in the light source device of FIG. The outline of the other structural example regarding 1st Embodiment of the light source device of this invention is shown. The optical path of a laser beam is shown in the light source device of FIG. The outline of the structure of 2nd Embodiment of the light source device of this invention is shown. The optical path of a laser beam is shown in the light source device of FIG. The outline of the other structural example regarding 2nd Embodiment of the light source device of this invention is shown. The optical path of a laser beam is shown in the light source device of FIG. The outline of the other structural example regarding 2nd Embodiment of the light source device of this invention is shown. The optical path of a laser beam is shown in the light source device of FIG. 1 schematically shows the configuration of an exposure apparatus of the present invention.

  [First Embodiment]

FIG. 1 shows an example of the configuration of the first embodiment of the light source device of the present invention. FIG. 2 shows an example of the configuration of a short arc type lamp used in the light source device of FIG. The first embodiment of the light source device includes a laser light feedback means 3 for reusing the laser light transmitted through the lamp only once.
The light source device 10 includes a light source 1, a laser oscillator 2, and laser light feedback means 3 surrounded by a dotted line. In this light source device 10, the lamp 11 of the light source 1 is turned on so that a plasma PZ is formed between the electrodes 114 and 115, and laser light emitted from the laser oscillator 2 to the plasma PZ in this state. Is emitted from the lamp 11 to emit high-power light.

  The light source 1 includes a short arc type lamp 11 and a concave reflecting mirror 12 that collects light emitted from the lamp 11. As shown in FIG. 2, the lamp 11 includes rod-shaped sealing portions 112 and 113 extending outward in the tube axis direction continuously from both ends of the light emitting portion 111 and the light emitting portion 111, and the inside of the light emitting portion 111. For example, a pair of electrodes 114 and 115 arranged to face each other with a distance of 1 to 3 mm, and power supply caps 116 and 117 attached to the sealing portions 112 and 113, respectively. The electrodes 114 and 115 are electrically connected to the caps 116 and 117, respectively.

  This lamp 11 is obtained by enclosing mercury as a discharge medium in the light emitting unit 111, and supplying AC power between a pair of electrodes by a power supply device (not shown) to form plasma between the pair of electrodes. For example, it emits i-line with a wavelength of 365 nm. As the discharge medium, xenon gas can be used instead of mercury.

The concave reflecting mirror 12 has a concave shape as a whole, and includes a light emitting port 12A formed at the front end edge and a reflecting surface 12B having a spheroid shape for reflecting the light emitted from the lamp 11. For example, when the light source of the present invention is applied to the exposure technique, the spheroid reflecting surface 12B reflects, for example, ultraviolet rays such as i-rays emitted from the lamp 11, so that, for example, HfO ₂ (hafnium oxide) and SiO ₂ (silicon oxide). Or a dielectric multilayer film formed by alternately stacking Ta ₂ O ₅ (tantalum oxide) and SiO ₂ (silicon oxide).

  Such a short arc type lamp 11 and the concave reflecting mirror 12 are such that the first focal point F1 of the concave reflecting mirror 12 substantially coincides between the electrodes 114 and 115 of the lamp 11 and the concave reflecting mirror 12 has the first focal point F1. The optical axis and the tube axis of the lamp 11 are arranged so as to be aligned substantially in a straight line, whereby the light source 1 is configured. Here, the tube axis of the lamp 11 means an imaginary line R that passes through the central axes of the electrodes 114 and 115 of the lamp 11, and the optical axis of the concave reflecting mirror 12 means the first axis of the concave reflecting mirror 12. It means an imaginary line M that passes through the first focal point F1 and the second focal point F2.

  The base 116 attached to the sealing portion 112 located on the light emitting side of the lamp 11 has a tapered portion 116A whose outer diameter gradually decreases as it goes in the light emitting direction. In this way, it becomes easy to prevent the laser light emitted from the laser oscillator 2 of FIG. 1 from being applied to the sealing portion 112 and the light emitting portion 111 in the lamp 11.

  The laser oscillator 2 can use a commercially available laser device such as a fiber laser or a semiconductor laser. The laser oscillator emits laser light having a wavelength of 809 nm or 1 μm, for example. The laser light has a wavelength other than the wavelength mainly used in the light emitted from the lamp 11. For example, when ultraviolet light having a wavelength of 365 nm emitted from the lamp 11 is used for exposure, the wavelength of the laser light needs to be other than 365 nm.

  The laser beam feedback means 3 includes a polarization beam splitter 31, lenses 32 and 33, a λ / 2 plate 34 that is a polarization rotation element, and optical elements 35 and 36. The polarization beam splitter 31 has a configuration in which, for example, two right-angle prisms are bonded together and a dielectric multilayer film or a metal thin film is coated on the joint surface. The polarization beam splitter 31 is used to separate linearly polarized light, reflects only S-polarized light and transmits P-polarized light. The lenses 32 and 33 are disposed so as to have a focal point at the second focal point F2 of the concave reflecting mirror 12. The λ / 2 plate 34 is capable of changing the polarization direction of linearly polarized light by 90 ° by generating a phase difference of π between orthogonal polarization components. The optical elements 35 and 36 are mirrors arranged so that the laser light collected by the lens 33 is incident on the λ / 2 plate 34 and the polarization beam splitter 31 in this order. Reference numeral 4 denotes a beam damper for capturing laser light.

  FIG. 3 is a conceptual diagram showing an optical path of laser light emitted from the laser oscillator 2. 3, “S” indicates S-polarized light having a polarization direction in a direction perpendicular to the paper surface of FIG. 3, and “P” indicates P-polarized light having a polarization direction in a direction horizontal to the paper surface of FIG. As shown in FIG. 3A, the S-polarized laser light L 1 emitted from the laser oscillator 2 travels toward the laser light feedback means 3. In FIG. 3A, the S-polarized light path from the laser oscillator 2 to the plasma PZ is indicated by a solid line. The laser light L 1 that has traveled to the laser light feedback means 3 enters the polarizing beam splitter 31 from the 90 ° direction of the polarizing beam splitter 31. The laser beam L 1 that is S-polarized light is reflected toward the light source 1 by the polarization beam splitter 31 and enters the lens 32. The laser light L1 is condensed by the lens 32 onto the second focal point F2 of the concave reflecting mirror 12 and enters from the light exit port 12A of the concave reflecting mirror 12. The laser beam L1 is reflected toward the vicinity of the gap between the pair of electrodes 114 and 115 in the lamp 11 by the reflecting surface 12B, and is condensed near the plasma PZ formed between the poles of the pair of electrodes 114 and 115. . The lamp 11 is in a state in which plasma PZ is generated between the pair of electrodes 114 and 115 by supplying power to the pair of electrodes 114 and 115 before emitting the laser beam L1 from the laser oscillator 2. . The plasma PZ of the lamp 11 is irradiated with the laser beam L1, so that energy is input and the temperature of the plasma PZ generated in the lamp rises.

  A part of the laser light L1 is absorbed by the plasma PZ, but a part that is not absorbed by the plasma PZ passes through the plasma PZ and enters the reflecting surface 12B of the concave reflecting mirror 12. In FIG. 3A, the laser beam that has passed through the plasma PZ is denoted by L2, and is indicated by a broken line. The laser beam L2 that has passed through the plasma PZ is reflected by the reflecting surface 12B and is emitted from the light exit port 12A of the concave reflecting mirror 12. The laser beam L2 is focused on the second focal point F2 of the concave reflecting mirror 12 and is incident on the lens 33. The laser beam L 2 incident on the lens 33 is reflected by the optical element 35 and passes through the λ / 2 plate 34. As a result, the laser beam L2 becomes P-polarized light whose polarization direction is rotated by 90 ° and polarized in a direction horizontal to the paper surface. The laser beam L 2 that has become P-polarized light is reflected by the optical element 36 and enters the polarization beam splitter 31. The polarization beam splitter 31 reflects S-polarized light and transmits P-polarized light. Therefore, the P-polarized laser light L2 passes through the polarization beam splitter 31, travels on the same optical path as the optical path shown in FIG. 3A, and is irradiated again on the plasma PZ in the lamp 11. That is, as will be described below, the laser light that has passed through the plasma PZ is reused via the laser light feedback means 3.

  FIG. 3B is a conceptual diagram showing the optical path of P-polarized light that has passed through the polarization beam splitter 31. In FIG. 3B, laser light that passes through the polarization beam splitter 31 and is irradiated onto the plasma PZ is denoted by L3, and its optical path is indicated by a broken line. The laser beam L3 that has passed through the polarization beam splitter 31 enters the lens 32. The laser beam L3 is condensed by the lens 32 onto the second focal point F2 of the concave reflecting mirror 12 and is incident on the reflecting surface 12B of the concave reflecting mirror 12. The laser beam L3 is reflected by the reflecting surface 12B and irradiated on the plasma PZ of the lamp 11. That is, in the light source device of the present invention, the laser light feedback means 3 is provided so that the laser light transmitted through the plasma PZ is once again irradiated to the plasma PZ, so that the laser light transmitted through the plasma PZ is not wasted. It can be reused effectively.

  Note that part of the laser light L3 shown in FIG. 3B that is not absorbed by the plasma PZ also passes through the plasma PZ. In FIG. 3B, the laser beam transmitted through the plasma PZ is denoted as L4 and indicated by a one-dot chain line. The laser beam L4 that has passed through the plasma PZ is reflected by the reflecting surface 12B of the concave reflecting mirror 12 and is emitted from the light exit port 12A. The laser beam L4 is focused on the second focal point F2 of the concave reflecting mirror 12, and then enters the lens 33. The laser beam L 4 incident on the lens 33 is reflected by the optical element 35 and passes through the λ / 2 plate 34. As a result, the laser beam L4 becomes S-polarized light whose polarization direction is rotated by 90 ° and polarized in a direction perpendicular to the paper surface. The laser beam L 4 that has become S-polarized light is reflected by the optical element 36 and enters the polarizing beam splitter 31. Since the laser beam L4 is S-polarized light, it is reflected by the polarization beam splitter 31 and captured by the beam damper 4. That is, in the light source device 10, the laser beam that has passed through the plasma PZ is reused only once.

As described above, according to the present invention, the radiation intensity of the light emitted from the plasma PZ is increased by irradiating the plasma PZ of the lamp 11 with the laser light to raise the temperature of the plasma PZ. it can.
Moreover, in the present invention, as shown in FIG. 3 (B), the laser light that has passed through the plasma PZ without being absorbed by the plasma PZ of the lamp 11 is again irradiated to the plasma PZ through the laser light feedback means 3, Since the laser light transmitted through the plasma PZ can be effectively reused without being wasted, the utilization efficiency of the laser light becomes high.
Further, since the laser light is incident from the side of the light exit 12A of the concave reflecting mirror 12, it is not necessary to form an opening for entering the laser light in the reflecting surface 12B of the concave reflecting mirror 12, and the reflecting surface 12B. Therefore, the light use efficiency of the lamp 11 is improved.

FIG. 4 shows another configuration relating to the first embodiment of the light source device of the present invention. In the light source device of FIG. 1, the laser light emitted from the laser oscillator was S-polarized linearly polarized light. 4 differs from that of FIG. 1 in that the laser beam emitted from the laser oscillator 2 is P-polarized linearly polarized light, and the configuration common to that of FIG. 1 is the same as that of FIG. The code | symbol is attached | subjected.
4 includes a light source 1 including a lamp 11 and a concave reflecting mirror 12, a laser oscillator 2 that emits P-polarized laser light, a polarization beam splitter 31, lenses 32 and 33, a λ / 2 plate 34, and Laser light feedback means 3 including an optical element 35 and a beam damper 4 are provided. The optical element 35 is a pair of mirrors arranged so that the laser light transmitted through the plasma PZ is incident on the λ / 2 plate 34 and the polarization beam splitter 31 in this order.

FIG. 5 is a conceptual diagram showing an optical path of laser light in the light source device 40 of FIG. In FIG. 5, “S” indicates S-polarized light having a polarization direction in a direction perpendicular to the paper surface of FIG. 5, and “P” indicates P-polarized light having a polarization direction in a direction horizontal to the paper surface of FIG. As shown in FIG. 5A, the P-polarized laser light L1 emitted from the laser oscillator 2 passes through the polarization beam splitter 31 and passes through the lens 32, and passes through the light exit port 12A of the concave reflecting mirror 12 to the concave reflecting mirror. 12 is incident on the inside, 12 is reflected by the reflecting surface 12B, and is irradiated to the plasma PZ of the lamp 11. Thereby, the radiation intensity of the light emitted from the plasma PZ is improved by increasing the temperature of the plasma PZ.
On the other hand, the laser beam L 2 that has passed through the plasma PZ is reflected by the reflecting surface 12 B of the concave reflecting mirror 12 and enters the λ / 2 plate 34 through the lens 33 and the optical element 35. The laser beam L 2 incident on the λ / 2 plate 34 is converted into S-polarized light by the polarization direction being rotated by 90 ° by the λ / 2 plate 34, and is incident on the polarization beam splitter 31. As shown in FIG. 5B, the S-polarized laser light L3 is reflected by the polarization beam splitter 31, travels through the same optical path as described in FIG. 5A, and is irradiated again to the plasma PZ. As shown in FIG. 5B, the laser light L4 transmitted through the plasma PZ through the laser light feedback means 3 is incident on the λ / 2 plate 34 through the lens 33 and the optical element 35, and λ / 2. After being converted to P-polarized light by the plate 34, the light passes through the polarization beam splitter 31 and is captured by the beam damper 4. As described above, in the light source device 40 of FIG. 4, by providing the laser light feedback means 3, the laser light transmitted through the plasma PZ can be reused, and the utilization efficiency of the laser light can be improved. .

FIG. 6 shows another configuration relating to the first embodiment of the light source device of the present invention. The light source device 60 of FIG. 6 differs from the light source device of FIG. 1 in that the reflecting surface 12B of the concave reflecting mirror 12 has a parabolic shape, and the configuration common to that of FIG. Detailed description will be omitted by adding reference numerals.
The light source device 60 of FIG. 6 includes a laser light feedback means 3 including a light source 1 including a lamp 11 and a concave reflecting mirror 12, a laser oscillator 2, a polarization beam splitter 31, a λ / 2 plate 34, and optical elements 35 and 36. And comprising. The optical elements 35 and 36 are a pair of mirrors arranged so that the laser light transmitted through the plasma PZ is incident on the λ / 2 plate 34 and the polarization beam splitter 31 in this order.

FIG. 7 is a conceptual diagram of an optical path of laser light in the light source device 60 of FIG. In FIG. 7, “S” indicates S-polarized light having a polarization direction in a direction perpendicular to the paper surface of FIG. 7, and “P” indicates P-polarized light having a polarization direction in a direction horizontal to the paper surface of FIG. As shown in FIG. 7A, the S-polarized laser light L 1 emitted from the laser oscillator 2 is reflected by the polarization beam splitter 31 and enters the concave reflecting mirror 12 through the light exit port 12 A of the concave reflecting mirror 12. Then, it is reflected by the reflecting surface 12B and irradiated to the plasma PZ of the lamp 11. Thereby, the radiation intensity of the light emitted from the plasma PZ is improved by increasing the temperature of the plasma PZ.
A part of the laser beam L1 incident on the plasma PZ passes through the plasma PZ without being absorbed by the plasma PZ. In FIG. 7A, the laser beam that has passed through the plasma PZ is indicated by a broken line and denoted by L2. The laser beam L2 that has passed through the plasma PZ is reflected by the reflecting surface 12B of the concave reflecting mirror 12 and enters the λ / 2 plate 34 through the optical element 35. The laser beam L2 incident on the λ / 2 plate 34 is converted into P-polarized light by the polarization direction rotated by 90 ° by the λ / 2 plate 34 and is incident on the polarization beam splitter 31.
In FIG. 7B, the P-polarized laser beam that has passed through the polarization beam splitter 31 is denoted by L3, and its optical path is indicated by a broken line. The laser beam L3 that has passed through the polarization beam splitter 31 travels on the same optical path as described with reference to FIG. 7A, and is irradiated again to the plasma PZ.
A part of the laser beam L3 shown in FIG. 7B that is not absorbed by the plasma PZ also passes through the plasma PZ. In FIG. 7B, laser light that has passed through the plasma PZ out of the laser light irradiated to the plasma PZ through the laser light feedback means 3 is denoted by L4 and indicated by a one-dot chain line. As shown in FIG. 7B, the laser light L4 that has passed through the plasma PZ is incident on the λ / 2 plate 34 through the optical element 35, converted into S-polarized light by the λ / 2 plate 34, and then optically transmitted. The light enters the polarization beam splitter 31 via the element 36. The S-polarized laser light L 4 incident on the polarization beam splitter 31 is reflected by the polarization beam splitter 31 and captured by the beam damper 4. Thus, in the light source device 60 of FIG. 6, by providing the laser light feedback means 3, the laser light transmitted through the plasma PZ can be reused, and the utilization efficiency of the laser light can be improved. .

  In the light source device of FIG. 6, P-polarized laser light can be emitted from the laser oscillator 2 toward the laser light feedback means 3.

[Second Embodiment]
FIG. 8 shows an example of the configuration of the light source device according to the second embodiment of the present invention. The light source device 80 of FIG. 8 is different from the light source device of FIG. 1 in that it includes laser light feedback means 8 for semipermanently reusing laser light that has passed through the plasma PZ, and is common to that of FIG. About the structure to perform, the same code | symbol as FIG.

  The light source device 80 includes a light source 1 including a lamp 11 and a concave reflecting mirror 12, a laser oscillator 2, laser light feedback means 8, and a beam damper 4. The laser light feedback means 8 includes a polarization beam splitter 31, lenses 32 and 33, a λ / 4 plate 84 which is a polarization rotation element, and optical elements 35 and 36. The λ / 4 plate 84 is disposed in the optical path of the laser light that has passed through the plasma PZ, and converts linearly polarized light into circularly polarized light. The optical elements 35 and 36 are a pair of mirrors arranged so that the laser light transmitted through the plasma PZ is incident on the λ / 4 plate 84 and the polarization beam splitter 31 in this order.

FIG. 9 is a conceptual diagram showing the optical path of laser light emitted from the laser oscillator 2. In FIG. 9, “S” indicates S-polarized light having a polarization direction in a direction perpendicular to the paper surface, and “P” indicates P-polarized light having a polarization direction in a direction horizontal to the paper surface. In FIG. 9A, the optical path of S-polarized light from the laser oscillator 2 to the plasma PZ of the lamp 11 is denoted by L1 and indicated by a solid line. As shown in FIG. 9A, the S-polarized laser light L 1 emitted from the laser oscillator 2 enters the polarization beam splitter 31 in the laser light feedback means 8. The laser beam L1 is reflected by the polarization beam splitter 31 toward the light source 1 and enters the lens 32. The laser beam L1 is collected by the lens 32 at the second focal point F2 of the concave reflecting mirror 12, and enters the reflecting surface 12B from the light exit port 12A of the concave reflecting mirror 12. The laser beam L1 incident on the reflecting surface 12B is irradiated to the plasma PZ formed between the pair of electrodes 114 and 115 in the lamp 11 by the reflecting surface 12B.
The lamp 11 is in a state in which plasma PZ is generated between the pair of electrodes 114 and 115 by supplying electric power to the pair of electrodes 114 and 115 before emitting the laser beam L1 from the laser oscillator 2. ing. The plasma PZ of the lamp 11 is irradiated with the laser beam L1, so that energy is input and the temperature of the plasma PZ rises.

  A part of the laser light L1 is absorbed by the plasma PZ, but a part that is not absorbed by the plasma PZ passes through the plasma PZ and enters the reflecting surface 12B of the concave reflecting mirror 12. In FIG. 9A, the laser beam that has passed through the plasma PZ is denoted by L2 and indicated by a broken line. As shown in FIG. 9A, the laser beam L2 that has passed through the plasma PZ is reflected by the reflecting surface 12B and is emitted from the light exit port 12A of the concave reflecting mirror 12. The laser beam L2 is focused on the second focal point F2 of the concave reflecting mirror 12 and is incident on the lens 33. The laser beam L2 is collimated by the lens 33, reflected by the optical element 35, and incident on the λ / 4 plate 84. The S-polarized laser light L2 is converted into circularly polarized light by the λ / 4 plate 84 and reflected by the optical element 36 toward the polarizing beam splitter 31.

  As shown in FIG. 9B, the polarization beam splitter 31 separates circularly polarized laser light into linearly polarized light having different polarization directions, reflects S-polarized light toward the beam damper 4 and transmits P-polarized light. . In FIG. 9B, the laser light transmitted through the polarization beam splitter 31 is denoted as L3, and its optical path is indicated by a broken line. The P-polarized laser light L3 that has passed through the polarization beam splitter 31 is incident on the lens 32, is condensed by the lens 32 onto the second focal point F2 of the concave reflecting mirror 12, and is concavely reflected from the light exit port 12A of the concave reflecting mirror 12. The light enters the inside of the mirror 12. The laser beam L3 is reflected by the reflecting surface 12B of the concave reflecting mirror 12, and is irradiated on the plasma PZ of the lamp 11.

  A part of the laser beam L3 shown in FIG. 9B that is not absorbed by the plasma PZ also passes through the plasma PZ. In FIG. 9B, laser light that has passed through the plasma PZ out of the laser light irradiated to the plasma PZ through the laser light feedback means 8 is denoted by L4 and indicated by an alternate long and short dash line. The laser beam L4 that has passed through the plasma PZ is reflected by the reflecting surface 12B of the concave reflecting mirror 12, is emitted from the light exit port 12A, is focused on the second focal point F2 of the concave reflecting mirror 12, and then enters the lens 33. The laser light L4 is collimated by the lens 33, passes through the λ / 4 plate 84, and is converted from P-polarized light to circularly-polarized light. The circularly polarized laser beam L4 is reflected by the optical element 36 and incident on the polarization beam splitter 31, and the polarization beam splitter 31 separates the laser beam L4 into linearly polarized light having different polarization directions. As a result, the S-polarized laser light is reflected by the polarization beam splitter 31 toward the beam damper 4 and captured by the beam damper 4. On the other hand, P-polarized laser light is transmitted through the polarization beam splitter 31. The laser beam that has passed through the polarization beam splitter 31 passes through the same optical path as the laser beams L3 and L4, and is incident on the polarization beam splitter 31 again. In this way, the laser light transmitted through the plasma PZ is continuously irradiated onto the plasma PZ semipermanently.

  As described above, in the light source device shown in FIG. 8, the laser light (L2, L4) transmitted through the plasma PZ of the lamp 11 is sequentially incident on the λ / 4 plate 84 and the polarization beam splitter 31 that are polarization rotation elements. It is supposed to be configured. Therefore, the laser light that has passed through the plasma PZ circulates semi-permanently between the light source 1 and the laser light feedback means 8. Therefore, the laser light transmitted through the plasma PZ can be reused semipermanently, and the utilization efficiency of the laser light can be remarkably improved.

  In the light source device shown in FIG. 8, the laser oscillator 2 emits S-polarized laser light toward the laser light feedback means 8. Of course, the present invention is not limited to this, and the laser oscillator 2 may emit P-polarized laser light.

FIG. 10 shows another configuration relating to the second embodiment of the light source device of the present invention. The light source device 100 of FIG. 10 is different from the light source device of FIG. 8 in that the reflecting surface 12B of the concave reflecting mirror 12 has a parabolic shape, and the configuration common to that of FIG. Detailed description will be omitted by adding reference numerals.
The light source device 100 of FIG. 10 includes a light source 1 including a lamp 11 and a concave reflecting mirror 12, a laser oscillator 2, a laser light feedback means 8, and a beam damper 4. The laser light feedback means 8 includes a polarization beam splitter 31, a λ / 4 plate 84, and optical elements 35 and 36. The optical elements 35 and 36 are a pair of mirrors arranged so that the laser light transmitted through the plasma PZ is incident on the λ / 4 plate 84 and the polarization beam splitter 31 in this order.

FIG. 11 is a conceptual diagram showing an optical path of laser light in the light source device 100 of FIG. In FIG. 11A, the laser light emitted from the laser oscillator 2 is indicated by a solid line and denoted as L1. As shown in FIG. 11A, the S-polarized laser light L 1 emitted from the laser oscillator 2 is reflected by the polarization beam splitter 31 and enters the concave reflecting mirror 12 from the light exit port 12 A of the concave reflecting mirror 12. Then, it is reflected by the reflecting surface 12B and irradiated to the plasma PZ of the lamp 11. As a result, the temperature of the plasma PZ is increased, and the radiation intensity of the light emitted from the plasma PZ is improved.
A part of the laser beam L1 incident on the plasma PZ passes through the plasma PZ without being absorbed by the plasma PZ. In FIG. 11A, the laser beam that has passed through the plasma PZ is indicated by a broken line and denoted as L2. The laser beam L2 that has passed through the plasma PZ is reflected by the reflecting surface 12B of the concave reflecting mirror 12 and enters the λ / 4 plate 84 via the optical element 35. The S-polarized laser light L2 is converted into circularly polarized light by the λ / 4 plate 84 and reflected by the optical element 36 toward the polarizing beam splitter 31.

  As shown in FIG. 11B, the polarization beam splitter 31 separates the incident circularly polarized laser light into linearly polarized light having different polarization directions, reflects S-polarized light toward the beam damper 4 and converts P-polarized light. Make it transparent. In FIG. 11B, the P-polarized laser light transmitted through the polarization beam splitter 31 is denoted as L3 and its optical path is indicated by a broken line. The P-polarized laser light L3 transmitted through the polarizing beam splitter 31 enters the concave reflecting mirror 12 from the light exit port 12A of the concave reflecting mirror 12. The laser beam L3 is reflected by the reflecting surface 12B of the concave reflecting mirror 12, and is irradiated on the plasma PZ of the lamp 11.

A part of the laser light L3 shown in FIG. 11B that is not absorbed by the plasma PZ also passes through the plasma PZ. In FIG. 11B, laser light that has passed through the plasma PZ out of the laser light irradiated to the plasma PZ through the laser light feedback means 8 is denoted by L4 and indicated by an alternate long and short dash line. The laser beam L4 that has passed through the plasma PZ is reflected by the reflecting surface 12B of the concave reflecting mirror 12, is emitted from the light exit 12A, is reflected by the optical element 35, passes through the λ / 4 plate 84, and is converted from P-polarized light. Converted to circularly polarized light. The circularly polarized laser beam L4 is reflected by the optical element 36 and incident on the polarization beam splitter 31, and the polarization beam splitter 31 separates the laser beam L4 into linearly polarized light having different polarization directions. As a result, the S-polarized laser light is reflected by the polarization beam splitter 31 toward the beam damper 4 and captured by the beam damper 4. On the other hand, P-polarized laser light is transmitted through the polarization beam splitter 31. The laser beam that has passed through the polarization beam splitter 31 passes through the same optical path as the laser beams L3 and L4, and is incident on the polarization beam splitter 31 again.
As described above, in the light source device 100 of FIG. 10, by providing the laser light feedback means 8, the laser light transmitted through the plasma PZ can be reused semi-permanently, so that the utilization efficiency of the laser light is improved. be able to.

  In the light source device of FIG. 10, the laser oscillator 2 emits S-polarized laser light toward the laser light feedback means 8. Of course, the present invention is not limited to this, and the laser oscillator 2 may emit P-polarized laser light.

FIG. 12 shows another configuration relating to the second embodiment of the light source device of the present invention. In the light source device 120 of FIG. 12, the reflecting surface 12B of the concave reflecting mirror 12 has a spheroid shape and is arranged in pairs, respectively, a λ / 2 plate 34, a polarizing beam splitter 31, and a λ / 4 plate 84. 10 and the polarization beam splitter 121 are different from those in FIG. 10, and the same reference numerals are given to components common to those in FIG. 10.
The light source device 120 of FIG. 12 includes a light source 1 including a lamp 11 and a concave reflecting mirror 12, a laser oscillator 2, a laser light feedback means 8, and a beam damper 4. The laser light feedback means 8 includes polarization beam splitters 31 and 121, lenses 32 and 33, a λ / 2 plate 34 and a λ / 4 plate 84 that are polarization rotation elements, and an optical element 36. In the laser light feedback means 13, the laser light transmitted through the plasma PZ passes through the lens 33, the λ / 4 plate 84, the polarizing beam splitter 121, the optical element 36, the λ / 2 plate 34, and the polarizing beam splitter 31 in this order. Arranged to go forward. Similar to the polarizing beam splitter 31, the polarizing beam splitter 121 has a configuration in which, for example, two right angle prisms are bonded together and a dielectric multilayer film or a metal thin film is coated on the joint surface.

FIG. 13 is a conceptual diagram showing the optical path of laser light emitted from the laser oscillator 2. In FIG. 13, “S” indicates S-polarized light having a polarization direction in a direction perpendicular to the paper surface, and “P” indicates P-polarized light having a polarization direction in a direction horizontal to the paper surface. In FIG. 13A, the optical path of S-polarized light from the laser oscillator 2 to the plasma PZ of the lamp 11 is denoted as L1 and indicated by a solid line.
As shown in FIG. 13A, the S-polarized laser light L 1 emitted from the laser oscillator 2 enters the polarization beam splitter 31 in the laser light feedback means 13. The laser beam L 1 that is S-polarized light is reflected toward the light source 1 by the polarization beam splitter 31 and enters the lens 32. The laser light L1 is condensed on the second focal point F2 of the concave reflecting mirror 12 by the lens 32, is incident on the reflecting surface 12B from the light exit port 12A of the concave reflecting mirror 12, and is applied to the plasma PZ of the lamp 11 by the reflecting surface 12B. Is irradiated.
The lamp 11 is in a state in which plasma PZ is generated between the pair of electrodes 114 and 115 by supplying electric power to the pair of electrodes 114 and 115 before emitting the laser beam L1 from the laser oscillator 2. ing. The plasma PZ of the lamp 11 is irradiated with the laser beam L1, so that energy is input and the temperature of the plasma PZ rises.

  A part of the laser light L1 is absorbed by the plasma PZ, but a part that is not absorbed by the plasma PZ passes through the plasma PZ and enters the reflecting surface 12B of the concave reflecting mirror 12. In FIG. 13A, the laser beam that has passed through the plasma PZ is denoted as L2 and indicated by a broken line. The laser beam L2 that has passed through the plasma PZ is reflected by the reflecting surface 12B and is emitted from the light exit port 12A of the concave reflecting mirror 12. The laser beam L2 is focused on the second focal point F2 of the concave reflecting mirror 12 and is incident on the lens 33. The laser beam L2 is collimated by the lens 33, passes through the λ / 4 plate 84, and is converted from S-polarized light to circularly-polarized light. The polarization component of the laser beam L2 converted into circularly polarized light is separated by the polarization beam splitter 121, the S polarization is reflected by the polarization beam splitter 121, and the P polarization is transmitted through the polarization beam splitter 121 and captured by the beam damper 4. The The S-polarized laser light L2 reflected by the polarization beam splitter 121 is reflected by the optical element 36 and passes through the λ / 2 plate 34. As a result, the laser beam L2 becomes P-polarized light by rotating the polarization direction by 90 °.

FIG. 13B is a conceptual diagram showing the optical path of P-polarized light that has passed through the polarizing beam splitter 31. In FIG. 13B, laser light that passes through the polarization beam splitter 31 and is irradiated onto the plasma PZ is denoted by L3, and its optical path is indicated by a broken line.
The P-polarized laser light L3 transmitted through the polarization beam splitter 31 is incident on the lens 32. The laser beam L3 is condensed by the lens 32 onto the second focal point F2 of the concave reflecting mirror 12 and is incident on the reflecting surface 12B of the concave reflecting mirror 12. The laser beam L3 is reflected by the reflecting surface 12B and irradiated on the plasma PZ of the lamp 11.

A part of the laser beam L3 shown in FIG. 13B that is not absorbed by the plasma PZ also passes through the plasma PZ. In FIG. 13B, the laser beam that has passed through the plasma PZ is denoted by L4 and indicated by a one-dot chain line. The laser beam L4 that has passed through the plasma PZ is reflected by the reflecting surface 12B of the concave reflecting mirror 12 and is emitted from the light exit port 12A. The laser beam L4 is focused on the second focal point F2 of the concave reflecting mirror 12, and then enters the lens 33. The laser light L4 is collimated by the lens 33, passes through the λ / 4 plate 84, and is converted from P-polarized light to circularly-polarized light. The laser beam L4 converted into circularly polarized light enters the polarization beam splitter 121, and the polarization component is separated by the polarization beam splitter 121. As a result, S-polarized light is reflected by the polarizing beam splitter 121, and P-polarized light is transmitted through the polarizing beam splitter 121 and captured by the beam damper 4. The S-polarized laser beam L4 reflected by the polarization beam splitter 121 is reflected by the optical element 36, passes through the λ / 2 plate 34, and the polarization direction is rotated by 90 ° to become P-polarized light. The laser beam L4 converted to P-polarized light passes through the polarization beam splitter 31, passes through the same optical path as the laser beams L3 and L4, and enters the beam splitter 31 again.
Thus, in the light source device of FIG. 12, since the laser light feedback means 8 is provided, the laser light transmitted through the plasma PZ can be reused semi-permanently, so that the utilization efficiency of the laser light is high. can do.
In addition, according to the light source device of FIG. 12, the energy of the laser light incident on each of the polarization beam splitters 31 and 121 is less than that of the light source device shown in FIGS. There is an advantage that the possibility of damage is extremely small.

  In the light source device of FIG. 12, the laser oscillator 2 emits S-polarized laser light toward the laser light feedback means 8. Of course, the present invention is not limited to this, and the laser oscillator 2 may emit P-polarized laser light.

In the above description, the lamp has an electrode as an example. However, the present invention can naturally be applied to a light source device including an electrodeless lamp. Further, when the incident laser beam does not have a desired beam diameter, it is naturally necessary to insert a beam expander between the laser oscillator and the element to which the laser beam is incident.
Further, in the above light source device, the driving timing of the lamp 11 and the driving timing of the laser oscillator 21 may be simultaneous, or either the lamp 11 or the laser oscillator 21 is driven first. Also good. In addition, after the plasma P is formed between the pair of electrodes 114 and 115 of the lamp 11, the plasma P may be irradiated with laser light in a state where power supply to the lamp 11 is stopped.

FIG. 14 describes an exposure apparatus using the light source device of the present invention.
The exposure apparatus 200 includes the light source device 10 and the optical system 140 shown in FIG. The light emitted from the light source device 10 is applied to the work 146 through the optical system 140. The optical system 140 includes a wavelength selective reflection mirror 141, an aperture 142, a collimator lens 143, an integrator lens 144, and a plane mirror 145.

The wavelength selective reflection mirror 141 is disposed in a state where the wavelength selection reflection mirror 141 obliquely intersects the optical axis of the concave reflection mirror 12. The light path of the light of the lamp 11 emitted from the concave reflecting mirror 12 is changed by the wavelength selective reflecting mirror 141. The wavelength selective reflecting mirror 141 reflects, for example, the light of the lamp 11 having a wavelength of 365 nm emitted from the concave reflecting mirror 12, while transmitting the laser light emitted from the laser oscillator 2, for example, having a wavelength of 809 nm or 1 μm. Have reflection characteristics. Such reflection characteristics are realized, for example, by forming a dielectric multilayer film in which TiO ₂ (titanium oxide) or the like is laminated so as to have a desired film thickness. The reflecting surface has a function of selectively reflecting the light in the specific wavelength region described above by appropriately setting the film thickness of the dielectric multilayer film and the total number of films.

  The aperture 142 is disposed at the second focal point F2 of the concave reflecting mirror 12, and cuts light from the lamp 11 that does not pass through the second focal point F2. The collimator lens 143 collimates the light that has passed through the aperture 142. The integrator lens 144 shapes the light of the lamp 11 collimated by the collimator lens 143 into a desired shape.

  In FIG. 14, for convenience, the light emitted from the lamp 11 is indicated by a solid line, and the laser light emitted from the laser oscillator 2 is indicated by a broken line. The laser light emitted from the laser oscillator 2 is reflected toward the light source 1 through the laser light feedback means 3 and passes through the wavelength selective reflection mirror 141. The laser light transmitted through the wavelength selective reflection mirror 141 is incident from the light exit 12A side of the concave reflection mirror 12, is reflected by the reflection surface 12B, and is irradiated to the plasma PZ of the lamp 11. The lamp 11 is in a state where plasma PZ is generated when the laser light is emitted from the laser oscillator 2. That is, the plasma PZ is generated by supplying electric power to the pair of electrodes 114 and 115 of the lamp 11 a predetermined time before the laser beam is emitted from the laser oscillator 2. As described above, the laser light transmitted through the plasma PZ is once again irradiated to the plasma PZ by the laser light feedback means 3.

  The light emitted from the plasma PZ of the lamp 11 is reflected by the reflecting surface 12B of the concave reflecting mirror 12 and is emitted from the light emitting port 12A. As indicated by the solid line in FIG. 14, the light from the lamp 11 is reflected by the wavelength selective reflection mirror 141 and the optical path is changed, and then passes through the aperture 142. At that time, the light that does not pass through the second focal point F <b> 2 is cut by the aperture 142. The light that has passed through the aperture 142 is incident on the collimator lens 143, the integrator lens 144, and the plane mirror 145 in this order, is reflected by the plane mirror 145, changes the optical path, and is irradiated on the surface of the workpiece 146.

  In the above exposure apparatus of the present invention, the plasma PZ of the lamp 11 is irradiated with laser light to raise the temperature of the plasma PZ, thereby increasing the radiation intensity of the plasma PZ. Therefore, the irradiance of the workpiece 146 is high, the processing time can be greatly shortened, and batch exposure can be performed on an object to be processed having a large area. Also in this case, the driving timing of the lamp 11 and the driving timing of the laser oscillator 21 may be simultaneous, or either the lamp 11 or the laser oscillator 21 may be driven first. . In addition, after the plasma P is formed between the pair of electrodes 114 and 115 of the lamp 11, the plasma P may be irradiated with laser light in a state where power supply to the lamp 11 is stopped.

DESCRIPTION OF SYMBOLS 1 Light source 11 Lamp 111 Light emission part 112, 113 Sealing part 114, 115 Electrode 116, 117 Base 12 Concave-reflection mirror 12A Light-emission opening 12B Reflection surface 2 Laser oscillator 3 Laser light feedback means 31 Polarization beam splitter 32 Lens 33 Lens 34 λ / 2 plate 35 optical element 36 optical element 4 beam damper 8 laser light feedback means 84 λ / 4 plate 121 polarizing beam splitter 140 optical system 141 wavelength selective reflector 142 aperture 143 collimator lens 144 integrator lens 145 plane mirror 146 work S S Polarized light P P polarized light PZ Plasma

Claims (6)

A lamp enclosing a discharge medium;
A concave reflecting mirror having a concave reflecting surface for reflecting light emitted from the lamp;
A laser oscillator that emits laser light toward the lamp;
A polarizing beam splitter that reflects S-polarized laser light and transmits P-polarized laser light;
A polarization rotation element that changes the polarization direction of linearly polarized light that passes through the lamp and exits through the concave reflecting mirror;
An optical element that guides the linearly polarized light so that linearly polarized light that has passed through the lamp and exited through the concave reflecting mirror is incident on the polarization rotation element and the polarization beam splitter in this order. Light source device.   The lamp is composed of a light emitting portion in which a pair of electrodes are arranged to face each other, and a rod-shaped sealing portion that extends continuously outward from each end of the light emitting portion in the tube axis direction. 2. The light source device according to claim 1, wherein the concave reflecting mirror is arranged such that an optical axis of the concave reflecting mirror and a tube axis of the lamp are aligned.   The light source device according to claim 1, wherein the polarization rotation element is a λ / 2 plate.   The light source device according to claim 1, wherein the polarization rotation element is a λ / 4 plate.   2. The light source device according to claim 1, wherein the laser oscillator enters laser light from a light exit side of the concave reflecting mirror toward a reflecting surface of the concave reflecting mirror. An exposure apparatus comprising the light source device according to claim 1,
The light path of the lamp emitted from the light exit port of the concave reflecting mirror reflects the light of the lamp to change the optical path of the light of the lamp, while transmitting the laser light emitted from the laser oscillator. A wavelength selective reflection mirror is provided.

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