Patent Number: 
Section: claims

1. A UV light irradiating apparatus for irradiating a semiconductor substrate with UV light, comprising:a reactor in which a substrate-supporting table is provided, said reactor being provided with a light transmission window;a UV light irradiation unit connected to the reactor for irradiating a semiconductor substrate placed on the substrate-supporting table with UV light through the light transmission window, said UV light irradiation unit including at least one UV lamp; anda liquid layer-forming channel disposed between the light transmission window and the UV lamp for forming a liquid layer through which the UV light is transmitted, said liquid layer being formed by a liquid flowing through the liquid layer-forming channel, wherein the liquid layer-forming channel is formed by a double walled enclosure that comprises an inner wall and an outer wall for passing the liquid between the walls, said inner wall being spaced from the at least one UV lamp by a space which allows gas to flow therethrough, wherein each of the space, the inner wall, the liquid layer, and the outer wall encloses and fully encircles the at least one UV lamp, and the liquid layer-forming channel is configured to form a planar liquid layer between the at least one UV lamp and the substrate-supporting table, said planar liquid layer being disposed substantially in parallel to the substrate-supporting table. 2. The UV light irradiating apparatus according to claim 1, wherein the liquid layer is formed by the flowing liquid which has substantially or nearly no absorption of UV light having a wavelength of 250 nm or lower. 3. The UV light irradiating apparatus according to claim 2, wherein the liquid constituting the liquid layer is pure water or ion-exchanged water. 4. The UV light irradiating apparatus according to claim 1, wherein the liquid layer-forming channel is formed with a glass capable of transmitting UV light having a wavelength of 250 nm or lower. 5. The UV light irradiating apparatus according to claim 1, wherein the liquid layer-forming channel is formed by two transparent walls for passing the liquid therebetween. 6. The UV light irradiating apparatus according to claim 5, wherein a distance between the two walls is about 5 mm to 15 mm. 7. The UV light irradiating apparatus according to claim 1, wherein the UV lamp has an elongated shape. 8. The UV light irradiating apparatus according to claim 1, wherein the double walled enclosure has a liquid inlet port for introducing the liquid between the inner and outer walls and a liquid outlet port for discharging the liquid from between the inner and outer walls. 9. The UV light irradiating apparatus according to claim 1, where the double walled enclosure has an inert gas inlet port for introducing inert gas into an interior enclosed by the inner wall and an inert gas outlet port for discharging the inert gas from the interior. 10. The UV light irradiation apparatus according to claim 1, wherein the liquid layer-forming channel is disposed in parallel to and closer to the UV light transmission window than to the UV lamp. 11. The UV light irradiating apparatus according to claim 1, wherein the UV light transmission window constitutes the liquid layer-forming channel. 12. The UV light irradiating apparatus according to claim 1, wherein the UV irradiation unit is provided with a reflection plate disposed along an inner wall of the UV irradiation unit, said reflection plate being angled to reflect UV light from the UV lamp toward the UV light transmission window. 13. The UV light irradiating apparatus according to claim 1, wherein the liquid layer-forming channel has a liquid inlet port for introducing the liquid into the channel and a liquid outlet port for discharging the liquid from the channel and is provided with a temperature sensor disposed at the liquid outlet port for detecting a temperature of the liquid at the liquid outlet port. 14. The UV light irradiating apparatus according to claim 13, wherein the liquid layer-forming channel is provided with a flow controller disposed upstream of the liquid inlet port for controlling the liquid flow according to the temperature detected by the temperature sensor.