Patent Number: 055815901
Section: summary

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an SOR exposure system which uses synchrotron radiation light from an SOR ring and, more particularly, to an SOR exposure system for transferring patterns on masks onto semiconductor wafers used in the field of manufacturing semiconductor devices. 2. Description of the Related Art The use of synchrotron radiation (hereinafter referred to as SOR radiation) as a light source for X-ray exposure has been proposed. A method has been considered in which a sheet-like beam of SOR radiation is expanded perpendicular to the plane of the beam using a mirror, and an exposure region is thereby created. In this method, as disclosed in Japanese Patent Laid-Open No. 2-98121, the damage to mirrors caused by X-rays is reduced by providing, in addition to an exposure adjustment shutter for controlling exposure time, a mirror-protective shutter for shielding X-rays disposed in a portion of the radiation path nearer to the X-ray source than the mirror, and the opening/closing of this shutter is controlled. There has been a problem in that, in addition to X-rays, radiation rays such as .alpha. particles, .beta. particles, .gamma. rays, or neutrons, all of which are harmful to the human body, are generated when electrons are implanted into an SOR ring and when the SOR ring stops. As shown in FIG. 11, a method to shield these radiation rays has been proposed in which an SOR ring 1 and an exposure apparatus 2 are placed in separate chambers and a partition 6 is formed into a radiation-ray shielding wall made of, for example, concrete. However, although the partition 6 has a duct 18 through which X-rays 3 are permitted to pass, no measures have been taken against leakage of radiation rays from the duct 18. These radiation rays are transmitted through a mirror-protective shutter provided to shield X-rays, causing damage to the mirror. SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, a primary object of the present invention is to provide an SOR exposure system which aims to protect the human body, stabilizing a mirror's reflectance for a long period of time, and to make maintenance easy. Another object of the present invention is to provide a method of manufacturing semiconductor devices, which employs the SOR exposure system. According to one aspect of the present invention which achieves these objectives, there is provided an SOR exposure system comprising: an SOR ring which emits SOR radiation, at least one exposure apparatus for exposing with the SOR radiation, a beam port through which the SOR ring is connected to each exposure apparatus and the SOR radiation is guided, and an X-ray reflecting mirror, disposed inside the beam port, for expanding the SOR radiation perpendicularly, wherein a first shutter means for shielding at least .gamma. rays and a second shutter means for shielding X-rays are provided between the SOR ring and the mirror inside the beam port. According to a further aspect of the present invention, an SOR exposure system is provided having an SOR ring for emitting synchrotron radiation and at least one exposure apparatus. A beam port connects the SOR ring to the exposure apparatus, and a shielding wall between the SOR ring and the exposure apparatus shields harmful electromagnetic waves. A shutter is also provided in the beam port for shielding at least gamma rays. According to yet another aspect of the present invention, a method of manufacturing semiconductor devices is provided in which an SOR ring is caused to emit synchrotron radiation. A first shutter disposed between the SOR ring and an exposure apparatus is closed to shield at least gamma rays when they are generated from the SOR ring. Also, a second shutter is opened to transfer a circuit pattern on a mask to a wafer, and the amount of X-ray exposure is adjusted during the exposure process. According to still another aspect of the present invention, a semiconductor device is provided which is manufactured by a method in which an SOR ring is caused to emit synchrotron radiation, a first shutter disposed between the SOR ring and an exposure apparatus is closed to shield against at least gamma rays when they are generated from the SOR ring, a second shutter is opened to transfer a circuit pattern on a mask to a wafer, and the amount of X-ray exposure is adjusted during the exposure process. With the construction described above, pernicious influence upon the human body by radiation rays, such as .gamma. rays, which are generated when electrons are implanted into an SOR ring and when the SOR ring stops, and damage to mirrors can be prevented. Since it is preferable that the mirror protective shutter for shielding X-rays be opened/closed each time exposure is performed, and since the shutter for shielding .gamma. rays is heavy because it is made of heavy metals, such as lead, the mirrors are separately disposed so that the former is light in weight and has excellent durability and the latter need not be operated at a high speed because it is designed to reliably shield radiation rays and to be opened/closed only during electron implantation. Thus, the shutters can be designed with emphasis placed on their independent functions. Objectives and advantages in addition to those discussed above shall be apparent to those skilled in the art from the description of the preferred embodiments of the invention which follow. In the description, reference is made to the accompanying drawings, which form a part hereof, and which illustrate an example of the invention. Such example, however, is not exhaustive of the various embodiments of the invention, and therefore reference is made to the appended claims for determining the scope of the invention.