JP3519116B2 - Microwave excitation light source device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device using an electrodeless lamp which emits light by generating an induced discharge by microwaves.
The present invention relates to a light source device suitable for linear or planar uniform irradiation. Such a light source device is used, for example, to decompose and remove a resist applied on a semiconductor wafer in a semiconductor manufacturing process using ozone and ultraviolet rays. 2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 63-224193 discloses a microwave-excited light source device in which a plurality of electrodeless lamps are provided in a cavity resonator to perform uniform irradiation in a plane. I have. FIG. 8 is a schematic configuration diagram showing a conventional microwave excitation light source device. As shown in the figure, for example, a plurality of straight tube-shaped or spherical electrodeless lamps 2 are arranged in a plane in a flat rectangular cavity resonator 1, and the lower surface of the cavity resonator is formed by a wire mesh 3. , Light can be extracted. [0004] The cavity resonator 1 is provided with a power supply port 4, and microwave power is supplied from a microwave power supply 6 via a waveguide 5, so that electromagnetic waves can be kept within the cavity. Since a wave is generated, the lamp 2 for the above-mentioned application is arranged on the mountain portion of the standing wave, and the ultraviolet light is irradiated in a plane. [0005] The size of the cavity resonator 1 used in the prior art is determined so as to resonate with the wavelength of microwaves. Starts, the resonance frequency changes, so that a resonance frequency adjusting screw or stub must be provided in the resonator, and the resonance position must be reset by trial and error. Further, since the peaks and valleys of the standing wave due to the electromagnetic waves exist two-dimensionally in the cavity 1, the lamps are arranged, for example, along a plurality of standing wave peaks standing in one direction. In this case, there is a problem in that the standing wave standing in the other direction causes uneven light emission in the longitudinal direction of the straight tube lamp and in the linear arrangement direction of the spherical lamp. Therefore, in order to eliminate the emission unevenness and to improve the uniformity of light in a plane, an attempt has been made to make two or more standing wave modes coexist in the cavity resonator. The length of at least two sides of the container must be changed so as to be simultaneously increased, which causes a problem of cost increase. Moreover, in the vicinity of the side wall of the cavity resonator, the electric field intensity is gradually reduced even by using this method, and as a result, the uniformity of the emission intensity distribution is reduced. According to the present invention, there is provided a microwave power supply, a rectangular waveguide for introducing a microwave output from the microwave power supply, and a microwave introduced to the rectangular waveguide. The present invention is directed to a microwave-excited light source device including an electrodeless lamp that emits light by inducing an induced discharge, accommodates an electrodeless lamp in a lamp chamber, and switches between a basic mode and a basic mode between the lamp chamber and the rectangular waveguide. A multi-mode converter for converting into a TE wave composed of a mode and a higher-order mode, wherein a microwave power supply, a rectangular waveguide, a multi-mode converter, and a lamp chamber are electrically connected; Is
A power supply-side rectangular waveguide portion and a lamp-side rectangular waveguide portion are bounded by a discontinuous right angle portion formed on both E surfaces, and the power supply-side rectangular waveguide portion matches the rectangular waveguide. Formed as
The center axis of the power-supply-side rectangular waveguide section and the center axis of the lamp-side rectangular waveguide section are aligned, and the center axis of the lamp-side rectangular waveguide section is
The length of the long side of the inner wall is defined as the free space wavelength λ0 of the microwave.
(3/2) λ0 or more and of the rectangular waveguide on the lamp side
The length of the short side of the inner wall is the same as the short side of the rectangular waveguide on the power supply side
(1/2) λ0 or less, and the lamp chamber has a rectangular parallelepiped-shaped power supply port which is open to the whole surface so as to match the opening of the lamp-side rectangular waveguide portion, and a net-shaped surface. And a surface for terminating the microwave waveguide to cause a standing wave to stand inside the lamp chamber, and the electrodeless lamp has
The microwave waveguide is disposed along a position parallel to a surface on which the short-circuit is performed. By propagating a TE wave consisting of a fundamental mode and a higher-order mode in a rectangular waveguide, the in-plane distribution of an electric field perpendicular to the traveling direction of the microwave can be made uniform. Become. Therefore, by arranging the electrodeless lamp in the plane, it is possible to obtain a light source having excellent linear uniformity. Further, by extending the depth of the lamp chamber containing the electrodeless lamp in the traveling direction of the microwave and setting up a standing wave of the microwave in the lamp chamber, the electrodeless lamp is arranged at the peak of the standing wave. Then, a light source having a high degree of uniformity even in a plane can be obtained. Embodiment 1 FIG. 1 shows a first embodiment of a microwave excitation light source device according to the present invention, and is a schematic configuration diagram for obtaining a light source capable of linearly and uniformly irradiating. It is. As shown, a multi-mode converter 10 is provided between a rectangular waveguide 12 connected to a microwave power supply 11 and a lamp chamber 13, and a rectangular waveguide is accommodated in a lamp chamber containing an electrodeless lamp 14. Microwave power supply, so that microwave power is supplied from the microwave power supply via the tube and the multi-mode converter.
The rectangular waveguide, the multi-mode converter, and the lamp chamber are electrically connected to each other. Note that the multimode converter and the lamp chamber are made of the same material as the waveguide. As shown in FIG. 2, the multimode converter 10 has a discontinuous rectangular conductor in which the H planes (long sides) are parallel to each other and the E planes (short sides) are provided with a right angle portion. A wave tube, wherein the length of the long side of the inner wall is a '
And the inner wall of the power-supply-side rectangular waveguide portion 10A having the short side length b '
And a lamp-side rectangular waveguide portion 10B having a long side of a and a short side of the inner wall of b. The power supply side rectangular waveguide portion and the lamp side rectangular waveguide portion have a power supply side connection portion 10a and a lamp side connection portion 10b, respectively, and the lamp side connection portion is wider than the power supply side connection portion. ing. The power supply side connection portion 10a is connected to the microwave power supply 1
For example, when a magnetron having a frequency of 2.45 GHz (a free space wavelength of microwave λ ₀ = 12.24 cm) is used as a microwave power source, the magnetron is formed so as to match the rectangular waveguide 12 connected to 1. Power supply side rectangular waveguide section 10A
Is the same as JIS standard number WRJ-2.
By setting the size to 9 cm × 5.5 cm, microwaves in the TE ₁₀ mode that are incident on the power supply side connection portion through the rectangular waveguide can be transmitted from the power supply side rectangular waveguide portion to the lamp side rectangular waveguide portion 10.
It propagates to B, is converted to a TE wave consisting of TE ₁₀ mode and the higher mode is a basic mode. TE _mn propagating in the multimode converter 10
The following equation (1) holds for the guide wavelength λg of the mode TE wave. (1 / λg) ² = (1 / λ ₀ ) ² -[(m / 2a) ² + (n / 2b) ² ] (1) Therefore, the power supply side rectangular waveguide section 10A of
The length b ' of the short side of the inner wall and the rectangular waveguide portion 10B on the lamp side
The length b of the short side of the inner wall is kept at 5.5 cm which is equal to or less than (1/2) λ0 of the free space wavelength λ0 of the microwave, and m = 3, n = 0 is substituted into the above equation (1). And (1 / λ0) 2 −
The length a of the long side of the inner wall of the lamp-side rectangular waveguide portion obtained from (3 / 2a) 2> 0 is calculated as (λ 0/2) · 3 (m = 3) of the free space wavelength λ 0 of the microwave. above and then, deer also affects the possible to match the central axis of the lamp-side rectangular waveguide portion of the conductive <br/> source side rectangular waveguide section, TEm0 the lamp side rectangular waveguide section ( m = 1, 3, 5,...) mode microwaves can be propagated. If the length a of the long side of the inner wall of the lamp-side rectangular waveguide section 10B is, for example, m = 5, (λ 0/2) ·
5 (m = 5)> a, the multi-mode converter 1
The value of 0 enables the waves of the two modes of TE10 and TE30 to be simultaneously transmitted to the lamp chamber 13. In this case, the electric field distribution in the lamp-side rectangular waveguide portion 10B due to the wave in which the two modes are combined has high uniformity as shown by the solid line in FIG. Here, in the TEm0 mode, the reason why no wave of even order m is generated is that the structure of the multi-mode converter is symmetrical in the left-right direction. In addition,
The power-supply-side rectangular waveguide portion 10 which is the same as in the rectangular waveguide 12
The electric field distribution in A is shown in FIG. The lamp chamber 13 has a flat rectangular parallelepiped shape as shown in FIG.
A power supply port having an open surface 13A is provided so as to be aligned with the connecting portion 10b of FIG. 3, so that the electric field distribution in the lamp chamber is also indicated by the solid line in FIG. Also,
A surface 13B facing the surface 13A is formed by a wire mesh 13N,
Light can be extracted from this surface 13B, and the microwave waveguide is terminated and short-circuited. The other surfaces are closed. In the lamp chamber 13, a straight tube-shaped electrodeless lamp 14 has a surface 13 on which a microwave waveguide is terminated and short-circuited.
It is arranged along the peak of the standing wave standing at a position parallel to B, that is, from the surface 13B to the side of the multimode converter 10 at a position of 1/4 of the guide wavelength λg of the microwave. Note that the position of the lamp is best at the peak of the standing wave for efficient light emission. The electrodeless lamp 14 varies depending on the application. For example, when an ultraviolet light source is used, an ultraviolet transmitting material such as quartz is used as the material, and a rare gas such as Ne or Ar is used as a sealing material. There are various metals such as Hg, Cd, Zn and the like, and halides thereof. Further, in order to optimize the luminous intensity of the lamp, one end or both ends of the lamp are taken out from small holes provided in the side wall of the lamp chamber 13, and the portion is kept at a temperature corresponding to the optimum vapor pressure of the sealed metal. Temperature may be controlled. For example, when Hg is encapsulated in a small amount and ultraviolet light having wavelengths of 185 nm and 254 nm is used, it is cooled with a liquid such as water so as to keep the temperature at 40 to 70 ° C. In this case, in order to prevent the microwave from leaking outside, it is necessary to cover the lamp portion exposed to the outside with a metal shielding box, though not shown. FIG. 4 is a diagram showing the luminous intensity distribution according to the present invention in the Ne gas-filled straight tube lamp. The light source device has the same configuration as that of the first embodiment shown in FIG. The length a of the long side of the inner wall of the lamp-side rectangular waveguide portion 10B of the multi-mode converter 10 was 490 mm. In this case, from the equation (1), the waves in the TE10, TE30, TE50 and TE70 modes are combined. Waves in other modes, if any, attenuate rapidly and do not propagate through the multimode converter. Among the multiplex modes, the ratio of the TE10 and TE30 modes is high. The straight tube lamp is arranged from the surface 13B toward the multimode converter 10 at a position which is 1/4 of the average value of these two guide wavelengths λg = 12.34 cm and 13.20 cm. As can be seen from FIG. 4, the uniformity is within ± 15% on a straight line of 40 cm, and is dramatically improved. As described above, by improving the uniformity of one straight tube lamp as a belt-like light source, the straight tube lamps can be two-dimensionally arranged and applied to uniform planar irradiation. <Embodiment 2> FIG. 5 shows a second embodiment of a microwave excitation light source device according to the present invention, and is a schematic configuration diagram for obtaining a light source capable of uniformly irradiating in a plane. In this embodiment, the lamp chambers shown in the first embodiment are stacked and arranged in a plane. As shown in the drawing, the microwave output from the microwave power supply and propagating through the rectangular waveguide enters a microwave distributor 20 having two waveguides. The output side of each waveguide 20A, 20B of this microwave distributor is connected to the power supply side connection portion of each of the multimode converters 10, 10 as in the first embodiment, and the respective lamp side. In the connection part, a lamp chamber 13 containing the electrodeless lamps 14, 14 is provided.
13 are provided. In the present embodiment, the microwave power is distributed into four equal parts by using two microwave distributors 20, 20, but the number of microwave distributors and the waveguides of the microwave distributors , The number of rectangular waveguides, and the number of microwave power supplies can be appropriately selected. <Embodiment 3> FIG. 6 shows a third embodiment of the microwave-excited light source device according to the present invention, and is a schematic configuration diagram for obtaining a light source capable of uniformly irradiating in a plane. In this embodiment, the lamp chamber shown in the first embodiment is expanded in a plane in the direction in which microwaves travel. As shown in the figure, the lamp chamber 13 connected to the same multi-mode converter 10 as in the first embodiment has a surface 13B for terminating and short-circuiting the microwave waveguide closed, and a surface 13C is formed of a wire mesh 13N. In this lamp chamber, a plurality of straight tube lamps 14, 14,... Are respectively directed from the surface 13B to the multi-mode converter 10 side to １ ／ of the guide wavelength λg of the microwave.
Are arranged along the ridges of a plurality of standing waves standing at the repetition position. <Embodiment 4> FIG. 7 shows a fourth embodiment of the microwave excitation light source device according to the present invention, and is a schematic configuration diagram for obtaining a light source capable of uniformly irradiating in a plane. This embodiment is a modification of the lamp chamber of the third embodiment. As shown in the figure, the lamp chamber 13 connected to the multi-mode converter 10 has its upper surface 13D inclined so that the distance between the lower surface 13C and the upper surface 13D
It has a tapered shape that gradually decreases in the B direction. This is because, as shown in the third embodiment, when a plurality of lamps 14 are arranged in the lamp chamber, the microwave power is attenuated from the microwave introduction side toward the terminal end due to the luminescence absorption of the lamps. This attenuation of the microwave power can be compensated for by making the lamp chamber tapered. In this case, make the taper of the lamp room narrower,
Do not disturb the microwave mode. Although the taper is narrowed down linearly, it may be narrowed down with an appropriate curvature. In the above embodiment, the length a of the long side of the inner wall of the rectangular waveguide portion on the lamp side of the multimode converter 10 is represented by
Higher order TE waves can be propagated by widening by an odd multiple of １ ／ of the free space wavelength of the microwave. Further, a straight tube lamp as the electrodeless lamp 14 is
A U-shaped lamp or a spherical lamp may be used, and a flat lamp can irradiate a wide area. Further, the microwave may be supplied with power continuously or may be supplied in pulse form (pulse discharge). Further, a movable stub type matching unit may be provided between the rectangular waveguide 12 and the multi-mode converter 10 as appropriate. As described above, according to the present invention, the straight tube lamp can be used in the longitudinal direction without any adjustment work and without increasing the cost by increasing the size of the apparatus. In a spherical lamp, the emission intensity distribution in the linear arrangement direction can be made more uniform, and the uniformity range of the emission intensity distribution can be expanded. By arranging them in a plane, it is possible to make the plane irradiation more uniform.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing a first embodiment of a microwave excitation light source device according to the present invention. FIG. 2 is a schematic configuration diagram showing a multimode converter according to the present invention. 3A is a diagram showing an electric field distribution in a lamp-side rectangular waveguide portion of the multimode converter of the present invention, and FIG. 3B is a diagram showing an electric field distribution in a power supply-side rectangular waveguide portion. FIG. 4 is a diagram showing a light intensity distribution according to the present invention in a Ne gas-filled straight tube lamp. FIG. 5 is a schematic configuration diagram showing a second embodiment of the microwave excitation light source device according to the present invention. FIG. 6 is a schematic configuration diagram showing a third embodiment of the microwave excitation light source device according to the present invention. FIG. 7 is a schematic configuration diagram showing a fourth embodiment of the microwave excitation light source device according to the present invention. FIG. 8 is a schematic configuration diagram showing a conventional microwave excitation light source device. [Description of Signs] 10 Multi-mode converter 10A Power supply side rectangular waveguide section 10B Lamp side rectangular waveguide section 11 Microwave power supply 12 Rectangular waveguide 13 Lamp room 14 Electrodeless lamp

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yoshinori Tsuruta 2-1-1-11 Tagawa, Yodogawa-ku, Osaka-shi Inside (72) Inventor Takahiro Aoyama 2-1-1-11 Tagawa, Yodogawa-ku, Osaka-daiichi Co., Ltd. (56) References JP-A-64-14898 (JP, A) JP-A-2-46004 (JP, A) JP-A-4-339295 (JP, A) Japanese Utility Model Laid-Open No. 60-149206 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H05B 41/24 F21S 1/00 H01J 65/04

Claims (1)

(57) [Claim 1] A microwave power supply, a rectangular waveguide for introducing a microwave output from the microwave power supply, and a microwave introduced to the rectangular waveguide. A microwave-excited light source device comprising: an electrodeless lamp that generates and emits an inductive discharge; wherein the electrodeless lamp is housed in a lamp chamber, and between the lamp chamber and the rectangular waveguide, a fundamental mode to a fundamental mode. And a multi-mode converter for converting into a TE wave composed of a multi-mode converter and a higher-order mode, wherein the microwave power supply, the rectangular waveguide, the multi-mode converter, and the lamp chamber are electrically connected; The power supply side rectangular waveguide portion and the lamp side rectangular waveguide portion are separated by a discontinuous right angle portion formed on both E surfaces, and the power source side rectangular waveguide portion is formed by the rectangular conductive portion. Formed to match the tube Together to match the central axis of the lamp-side rectangular waveguide portion of the power supply-side rectangular waveguide section, the free space of the long side of the inner wall of the lamp-side rectangular waveguide section Microwave (3/2) λ of wavelength λ0
0, and the length of the short side of the inner wall of the lamp-side rectangular waveguide is the same as the short side of the power-supply-side rectangular waveguide (1/1 /
2) λ0 or less, the lamp chamber has a power supply port having a rectangular parallelepiped-shaped opening on one side so as to be aligned with the lamp-side rectangular waveguide portion, a net-shaped surface, A surface for short-circuiting the microwave waveguide so as to make a wave stand, and the electrodeless lamp is provided with a microwave excitation light source device arranged along a position parallel to the surface for short-circuiting the microwave waveguide. .