Patent Number: 051075245
Section: summary

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a synchrotron radiation utilizing apparatus and a method for utilizing synchrotron radiation. More particularly, this invention relates to an apparatus and a method as described above in which synchrotron radiation is utilized for the purpose of, for example, SOR lithography for manufacturing semiconductor devices. 2. Description of the Prior Art Synchrotron radiation emitted from high energy electrons (charged particles) circulating in a beam duct of a synchrotron radiation generator (an electron accumulator ring) contains soft X-rays which have a wavelength as short as about 10 .ANG. having good directivity and which have a high beam intensity. Therefore, the synchrotron radiation is noted as, for example, a lithography light source for manufacturing ultra LSI's of the next generation, and researches and studies for providing a synchrotron radiation generator apparatus of a small size are now being made. Apparatuses of this kind are disclosed in, for example, JP-A-63-175400 and JP-A-63-202900. An X-ray exposure apparatus utilizing synchrotron radiation is disclosed in JP-A-62-291027. In this apparatus, synchrotron radiation radiated in an orbital plane is reflected to the outside of the orbital plane by the use of an oscillating reflection mirror thereby attaining the desired purpose of scanning. On the other hand, an ion beam lithography apparatus disclosed in JP-A-62-5548 is known as an apparatus in which a wafer to be processed is revolved around the central axis of the apparatus while rotating around its own axis. The ion beam used in the known ion beam lithography apparatus is converged to meet the size of the wafer and is devoid of beam uniformity. In this known apparatus, the wafer is merely rotated around its own axis regardless of the period of its revolution around the central axis of the apparatus so that the entire wafer can be uniformly exposed to the ion beam. In the prior art apparatus disclosed in JP-A-62-291027 cited above, a distance of about 5 m is required for reflecting and magnifying the soft X-rays, resulting in a large size of the apparatus. Further, because the synchrotron radiation is reflected by the reflected mirror, the synchrotron radiation tends to be attenuated, resulting in an inevitable decrease in the quantity of the radiation that can be used for the exposure. Also, in the prior art apparatus disclosed in JP-A-62-5548 cited above, it is only necessary to merely rotate the wafer around its own axis because the beam used for the lithography is the ion beam. The synchrotron radiation differs from the ion beam in that it is converged into a very small diameter. Thus, when the synchrotron radiation is used in lieu of the ion beam, it is necessary to very precisely scan the wafer for the purpose of uniform exposure. SUMMARY OF THE INVENTION With a view to solve the various prior art problems, it is an object of the present invention to provide a synchrotron radiation utilizing apparatus utilizing synchrotron radiation for uniform exposure of objects, in which a large area can be scanned without attenuation of the synchrotron radiation, so that the objects can be uniformly irradiated with the synchrotron radiation. In an embodiment of the present invention which attains the above object, a plurality of objects which are targets to be irradiated with synchrotron radiation are mounted on a rotary support base having a perpendicular shaft in such a relation that the objects are arranged in an equally spaced relation along an imaginary circle drawn around the shaft, and the synchrotron radiation is directed toward the objects while rotating the support base. That is, according to one aspect of the present invention, there is provided a synchrotron radiation utilizing apparatus comprising means for generating synchrotron radiation, means for guiding the synchrotron radiation generated from the synchrotron radiation generating means in a predetermined direction, a plurality of supporting members each supporting one of a plurality of objects which are targets to be irradiated with the synchrotron radiation, the supporting members being disposed at positions distant substantially by an equal distance from the center of rotation of the apparatus, a support base rotatably supporting the object supporting members, first rotating means for rotating each of the object supporting members in a predetermined direction, first control means for applying a control signal to the first rotating means, second rotating means for rotating the support base in the plane of the support base in a direction opposite to the direction of rotation of the object supporting members, and second control means for applying a control signal to the second rotating means. Suppose the case where the plural supporting members supporting the objects (for example, wafers of silicon, gallium arsenide, etc.) which are the targets to be irradiated with the synchrotron radiation are mounted on the support base having the perpendicular shaft in such a relation that the supporting members are arranged in an equally spaced relation on an imaginary circle drawn around the shaft, and the synchrotron radiation is directed toward the objects while rotating both the support base and the supporting members. The radiation intensity distribution in the above case will now be discussed. When each of the supporting members is rotated at an angular velocity w, the rotation velocity at a point spaced by a distance Y from the center of the support base is expressed as Yw. The spot of the synchrotron radiation on each of the objects lies on a line, and the synchrotron radiation sweeps the object with the rotation of the supporting member. However, as described above, the rotation velocity of the object increases in proportion to the distance from the rotary shaft of the support base. This means that the quantity of the synchrotron radiation irradiating a unit area of the object per unit time decreases in inverse proportion to the distance from the rotary shaft of the support base. Thus, in the exposure apparatus having the above arrangement, such an undesirable non-uniform radiation intensity distribution results in which the intensity distribution is high at a radially inner area of the object but low at a radially outer area of the object. In the present invention which obviates such a disadvantage, means are provided so that the plural objects can be rotated at the angular velocity .omega. independently of each other in a direction opposite to the direction of rotation of the support base, so that the composite angular velocity becomes zero. Therefore, when the surface of the object is looked at from the position of an observer who stands still (for example, the operator of the exposure apparatus), the spot of the synchrotron radiation makes a substantially parallel movement on the surface of the object, so that the aforementioned problem of the non-uniform radiation intensity distribution attributable to the difference between the rotation velocities can be avoided. The synchrotron radiation utilizing apparatus, especially the objects preferably maintained in an atmosphere of a reduced pressure. When the plural objects are maintained in such an atmosphere, the objects can be efficiently exposed to the synchrotron radiation within a short period of time, and a very fine circuit pattern can be uniformly formed on the object, so that the productivity of semiconductor devices can be greatly improved. Applicable fields of the present invention include, besides that described above, analysis of trace elements or microelements using light absorption, determination of the arrangement of atoms of non-crystalline substances by measurement of spectral fine structures near absorption edges of an X-ray region, observation of lattice defects on the basis of diffraction spot images, analysis of the structure of macromolecules based on the small angle scattering method utilizing the parallelism of synchrotron orbital radiation (SOR), and measurement of distances between component atoms in alloys by the anomalous scattering method.