Patent Number: 
Section: claims

1. An ultraviolet irradiation device for irradiating with ultraviolet rays an ultraviolet curable protective tape joined to a surface of a semiconductor wafer, comprising:a holding table to mount and hold the semiconductor wafer with the protective tape joined thereto;a drive mechanism to turn the holding table;ultraviolet light emitting diodes arranged at least in a radial direction of the semiconductor wafer; anda control unit to maintain a uniform accumulated quantity of light in an area of the protective tape where ultraviolet rays are applied upon irradiation of a surface of the protective tape with ultraviolet rays from the ultraviolet light emitting diodes while turning the holding table that places and mounts the semiconductor wafer with the protective tape joined thereto,wherein supply voltage is controlled such that ultraviolet intensity from the ultraviolet light emitting diodes increases outwardly of the semiconductor wafer. 2. The ultraviolet irradiation device according to claim 1, further comprising:an amplifier to amplify the supply voltage to the ultraviolet light emitting diodes; anda controller to control the amplifier. 3. An ultraviolet irradiation device for irradiating with ultraviolet rays an ultraviolet curable protective tape joined to a surface of a semiconductor wafer, comprising:a holding table to mount and hold the semiconductor wafer with the protective tape joined thereto;a drive mechanism to turn the holding table;ultraviolet light emitting diodes arranged at least in a radial direction of the semiconductor wafer; anda control unit to maintain a uniform accumulated quantity of light in an area of the protective tape where ultraviolet rays are applied upon irradiation of a surface of the protective tape with ultraviolet rays from the ultraviolet light emitting diodes while turning the holding table that places and mounts the semiconductor wafer with the protective tape joined thereto,wherein a distance from the surface of the protective tape to the ultraviolet light emitting diodes decreases outwardly of the semiconductor wafer. 4. The ultraviolet irradiation device according to claim 3, further comprising:a sensor to measure intensity of ultraviolet rays from the ultraviolet light emitting diodes;a lifting mechanism to change each level of the ultraviolet light emitting diodes; anda level controller to control each level of the ultraviolet light emitting diodes based on detected result of the sensor through operation of the lifting mechanism so as to maintain a uniform accumulated quantity of light per area on the surface of the protective tape. 5. The ultraviolet irradiation device according to claim 4, further comprising:a drive mechanism to move the sensor between a position where the ultraviolet light emitting diodes apply ultraviolet rays and a position where the ultraviolet light emitting diodes apply no ultraviolet rays. 6. An ultraviolet irradiation device for irradiating with ultraviolet rays an ultraviolet curable protective tape joined to a surface of a semiconductor wafer, comprising:a holding table to mount and hold the semiconductor wafer with the protective tape joined thereto;a drive mechanism to turn the holding table;ultraviolet light emitting diodes arranged at least in a radial direction of the semiconductor wafer; anda control unit to maintain a uniform accumulated quantity of light in an area of the protective tape where ultraviolet rays are applied upon irradiation of a surface of the protective tape with ultraviolet rays from the ultraviolet light emitting diodes while turning the holding table that places and mounts the semiconductor wafer with the protective tape joined thereto,wherein spaces between the ultraviolet light emitting diodes are smaller outwardly of the semiconductor wafer. 7. The ultraviolet irradiation device according to claim 6, further comprising:a drive mechanism to move the ultraviolet light emitting diodes separately in a horizontal direction; anda controller to adjust the spaces between the ultraviolet light emitting diodes by control of the drive mechanism. 8. An ultraviolet irradiation device for irradiating with ultraviolet rays an ultraviolet curable protective tape joined to a surface of a semiconductor wafer, comprising:a holding table to mount and hold the semiconductor wafer with the protective tape joined thereto;a drive mechanism to turn the holding table;ultraviolet light emitting diodes arranged at least in a radial direction of the semiconductor wafer;a control unit to maintain a uniform accumulated quantity of light in an area of the protective tape where ultraviolet rays are applied upon irradiation of a surface of the protective tape with ultraviolet rays from the ultraviolet light emitting diodes while turning the holding table that places and mounts the semiconductor wafer with the protective tape joined thereto; anda lighting control unit to control intermittent lighting of each ultraviolet light emitting diode so as to extend a lighting duration of each ultraviolet light emitting diode outwardly of the semiconductor wafer. 9. An ultraviolet irradiation device for irradiating with ultraviolet rays an ultraviolet curable protective tape joined to a surface of a semiconductor wafer, comprising:a holding table to mount and hold the semiconductor wafer with the protective tape joined thereto;a drive mechanism to turn the holding table;ultraviolet light emitting diodes arranged at least in a radial direction of the semiconductor wafer;a control unit to maintain a uniform accumulated quantity of light in an area of the protective tape where ultraviolet rays are applied upon irradiation of a surface of the protective tape with ultraviolet rays from the ultraviolet light emitting diodes while turning the holding table that places and mounts the semiconductor wafer with the protective tape joined thereto; anda screen that is interposed between the semiconductor wafer and the ultraviolet light emitting diodes and has a slit formed therein that fans outwardly from the center of the semiconductor wafer. 10. An ultraviolet irradiation device for irradiating with ultraviolet rays an ultraviolet curable protective tape joined to a surface of a semiconductor wafer, comprising:a holding table to mount and hold the semiconductor wafer with the protective tape joined thereto;a drive mechanism to turn the holding table;ultraviolet light emitting diodes arranged at least in a radial direction of the semiconductor wafer;a control unit to maintain a uniform accumulated quantity of light in an area of the protective tape where ultraviolet rays are applied upon irradiation of a surface of the protective tape with ultraviolet rays from the ultraviolet light emitting diodes while turning the holding table that places and mounts the semiconductor wafer with the protective tape joined thereto; anda filter that is interposed between the semiconductor wafer and the ultraviolet light emitting diodes and has increased ultraviolet transmittance outwardly of the semiconductor wafer. 11. An ultraviolet irradiation device for irradiating with ultraviolet rays an ultraviolet curable protective tape joined to a surface of a semiconductor wafer, comprising:a holding table to mount and hold the semiconductor wafer with the protective tape joined thereto;a drive mechanism to turn the holding table;ultraviolet light emitting diodes arranged at least in a radial direction of the semiconductor wafer;a control unit to maintain a uniform accumulated quantity of light in an area of the protective tape where ultraviolet rays are applied upon irradiation of a surface of the protective tape with ultraviolet rays from the ultraviolet light emitting diodes while turning the holding table that places and mounts the semiconductor wafer with the protective tape joined thereto; andan auxiliary ultraviolet light emitting diode arranged at a site located at an outer periphery of the semiconductor wafer to apply an ultraviolet ray towards a peripheral edge of the protective tape.