Patent Number: 055966187
Section: summary

FIELD OF THE INVENTION AND RELATED ART This invention relates to an exposure apparatus of the type which uses, as illumination light, synchrotron radiation light, for example, produced from a charged particle accumulation ring. In order to meet recent further requirements miniaturization of semiconductor devices, the development of a variety of apparatuses capable of transferring and printing patterns of a minimum linewidth of 0.24 micron for a DRAM of not less than 100 megabits, has been advanced. Among these apparatuses, an exposure apparatus of the type which uses, as illumination light, synchrotron radiation light (SR-X-ray beam) produced by a charged particle accumulation ring shows superior performance both with respect to the transferring and printing precision and with respect to the productivity, and it is considered as an effective machine. The SR-X-ray beam is emitted from an emission point in the form of a sheet-like beam having a small thickness in a direction (Y-axis direction) perpendicular to the orbit of the charged particle accumulation ring. It is expanded in the Y-axis direction by an expanding device such as a cylindrical mirror, and then it is introduced into an exposure chamber to irradiate a mask and a substrate such as a wafer. The SR-X-ray beam expanded by a cylindrical mirror, for example, is uniform in the X-axis direction. But it has a non-uniform distribution in the Y-axis direction. Thus, it produces exposure non-uniformness. In consideration of this, a movable shutter being movable in the Y-axis direction is provided before the substrate and, by changing the movement speed of the movable shutter with time and in accordance with the intensity distribution of the SR-X-ray beam, the exposure time of the substrate is adjusted to prevent the exposure non-uniformness (Japanese Laid-Open Patent Application, Laid-Open No. 243519/1989). SUMMARY OF THE INVENTION With this method, however, the movement speed of the movable shutter has to be changed with time as each exposure zone of the substrate is subjected to the exposure process. This requires a large acceleration and deceleration of a driving motor of the movable shutter during the exposure process, and a large load is applied to the driving means mechanism. Also, vibration may be produced and transmitted to the substrate, which may adversely result in a transfer error (misregistration). It is an object of the present invention to provide an exposure apparatus in which driving control of a movable shutter, for example, is easy and in which production of vibration is effectively suppressed to avoid transfer error. In one preferred form of the invention, there is provided an exposure apparatus which comprises a holder for holding a substrate to be exposed, and a movable shutter being movable across the path of exposure light, having an intensity distribution with respect to a predetermined direction, and in a direction intersecting the predetermined direction. The movable shutter has an edge of a shape having a protrusion, protruding in the movement direction, and this protrusion has a shape and size determined on the basis of the intensity distribution of the exposure light. With this arrangement, the amount of exposure can be made uniform throughout each exposure zone of the substrate by moving the movable shutter over the exposure zone at a constant speed or an approximately constant speed. Thus, there is no necessity of a large acceleration and deceleration of the movable shutter in each exposure zone, and the driving control is easy. Also, vibration is not easily produced, enabling high precision exposure. These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.