Abstract:
The present invention aims at reducing the number of scanning exposure and at enhancing throughput. 
     the above-mentioned objective is achieved by allowing a substrate  14  to be placed in sideways with respect to a substrate holder  15   a  (placing the longer sides of the substrate in parallel to the shorter sides of the substrate holder) depending on the size of the apparatus and the size of the substrate  14 . It is acceptable even when areas other than an effective exposure area of the substrate  14  should project out from the substrate holder.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an exposure method. More particularly, the present invention relates to an exposure method for exposing a flat substrate to a pattern for fabricating a liquid crystal display panel, a plasma display panel, and the like. 
     BACKGROUND OF THE INVENTION 
     Display qualities of recent liquid crystal display panels and plasma display panels are remarkably enhanced. Moreover, the liquid crystal display panels and the plasma display panels are thin and light, and thus are becoming major image display apparatuses as substitutes for CRTs. Particularly, a direct-view type active matrix liquid crystal panel is making progress in enlarging its screen size, and to that end the size of glass substrates used for fabricating the liquid crystal panels are becoming larger as well. 
     As an exposure method for exposing a large-sized glass substrate to element patterns of a display panel, a scanning-type exposure method is known. According to the scanning-type exposure method, exposure is performed by synchronously scanning a photomask or a reticle having a pattern formed thereon (hereinafter, referred to as a “mask”) and a glass substrate applied with a photosensitive agent such as a photoresist (hereinafter, referred to as a “substrate”). 
     As an example, scanning exposure of a substrate to a mask pattern at one to one magnification will be described. Assume that the size of an effective exposure area of the mask is 400 mm×700 mm, the size of the substrate is 720 mm×900 mm, and the size of a substrate holder for carrying the substrate is 843 mm×890 mm. A scanning-type exposure apparatus, which synchronously transfers a mask stage (for supporting and transporting a mask) and a substrate stage (a substrate holder for supporting a substrate) with respect to a projection optical system, is used to expose a substrate to a pattern of a 17-inch SXGA liquid crystal display panel. The size of the 17-inch SXGA panel including a circuit pattern surrounding a pixel region is 279.7 mm×347.2 mm. 
     The size relationship is shown in FIGS. 7 and 8. FIGS. 7 and 8 are schematic views showing the sizes of a rectangular substrate holder  15   a  and a substrate  200  held by the substrate holder  15   a  (which is represented by dotted lines in FIG. 8 for distinction from the substrate  200 ), respectively. As shown in FIG. 8, the substrate  200  is loaded on the substrate holder  15   a  such that the longer sides of the substrate  200  are arranged along the longer sides of the substrate holder  15   a.    
     FIG. 9 is a schematic view for illustrating a manner of printing six 17-inch SXGA panels on the above-described substrate by using a mask  100  that has two 279.7 mm×347.2 mm circuit patterns  101  formed thereon. In FIG. 9, the substrate holder  15   a  is omitted. 
     With reference to FIG. 9, an exposure of patterns of 17-inch SXGA liquid crystal display panels is carried out as follows. First, a first scanning exposure is conducted by synchronously transferring the mask  100  and the substrate  200  in the X-direction as indicated by an arrow  1  to print two circuit patterns  101  on exposure areas  200   a  and  200   b  of the substrate  200 . 
     Then, the mask  100  and the substrate  200  are transferred back to the exposure initiating positions to perform a second scanning exposure to print a single circuit pattern  101  on an exposure area  200   c  as indicated by an arrow  2 . Since the length of the side of the substrate  200  is 900 mm, two circuit patterns  101  cannot be exposed at the second scanning exposure. 
     Next, while the substrate  200  is step transferred in the Y-direction, the mask  100  and the substrate  200  are transferred back to the exposure initiating positions to perform a third scanning exposure to print a single circuit pattern  101  on an exposure area  200   d  of the substrate  200  as indicated by an arrow  3 . Finally, two circuit patterns  101  are printed on exposure areas  200   e  and  200   f  as indicated by an arrow  4 . 
     According to such a conventional exposure method, even when the mask  100  is provided with two circuit patterns  101 , there is a case where only a single circuit pattern  101  can be printed at a time. As a result, the number of scanning exposure increases, limiting improvement of the throughput. 
     SUMMARY OF THE INVENTION 
     In view of the current situation of scanning exposure, the present invention has an objective of providing an exposure method which can be carried out with reduced number of scanning steps and at enhanced throughput. 
     According to the present invention, the above-mentioned objective is achieved by allowing a substrate to be placed in sideways (rotated by 900) with respect to a substrate holder (placing the longer sides of the substrate in parallel to the shorter sides of the substrate holder) depending on the size of the apparatus and the size of the substrate. When the substrate is placed in sideways with respect to the scanning direction, or the substrate holder, it is acceptable even when areas other than an effective exposure area of the substrate should project out from the substrate holder, since there is no need of precisely controlling flatness of areas of the substrate where they are not exposed to a pattern. 
     Along with the reference numerals, the present invention is an exposure method for exposing a rectangular substrate ( 14 ) to a pattern ( 30   a ) of a mask ( 30 ) by transferring a mask stage ( 20 ) carrying a mask ( 30 ) formed with the pattern ( 30 ) and a rectangular substrate holder ( 15   a ) carrying the substrate ( 14 ) in a first direction (X-direction), the method comprising: a step (S 22 ) of placing the substrate ( 14 ) whose longer sides are longer than the shorter sides of the substrate holder ( 15   a ), on the substrate holder ( 15   a ) such that the longer sides of the substrate ( 14 ) are generally arranged along the shorter sides of the substrate holder ( 15   a ); a step (S 25 ) of exposing a first area ( 14   a ,  14   b ) of the substrate ( 14 ) to the pattern ( 30   a ) of the mask ( 30 ) by transferring the mask stage ( 20 ) and the substrate holder ( 15   a ) in the first direction (X-direction); a step (S 26 ) of transferring the substrate holder ( 15   a ) in a second direction (Y-direction) which is generally perpendicular to the first direction (X-direction); and a step (S 27 ) of exposing a second area ( 14   c ,  14   d ) of the substrate ( 14 ), which is adjacent to the first area ( 14   a ,  14   b ) along the second direction (Y-direction), by transferring the mask stage ( 20 ) and the substrate holder ( 15   a ) in the first direction (X-direction). 
     According to the exposure method of the present invention, the number of scanning steps can be reduced, thereby realizing high throughput. 
     The exposure method of the invention can comply with the recent tendency toward enlargement of the substrate size, and can be applied without enlarging the exposure apparatus. For example, the exposure method of the invention is applicable to a substrate whose shorter side is 680 mm or longer and whose longer side is 880 mm or longer. 
     The first direction (X-direction) may be parallel to the longer sides of the substrate holder ( 15   a ). The first ( 14   a ,  14   b ) and second ( 14   c ,  14   d ) areas are positioned in a region where the substrate ( 14 ) is making contact with the substrate holder ( 15   a ). Alignment marks are preferably formed in a region where the substrate ( 14 ) is making contact with the substrate holder ( 15   a ). 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view showing a structure of a scanning-type exposure apparatus according to an embodiment of the invention; 
     FIG. 2 is a plan view showing a substrate  14  loaded on a substrate stage  15 ; 
     FIG. 3 is a plan view showing a mask  10 ; 
     FIG. 4 is a schematic plan view showing a substrate  14  supported by a substrate holder  15   a;    
     FIG. 5 is a schematic plan view showing a manner of printing six 17-inch SXGA LCD panels on the substrate  14  by using a mask  30  that has two 347.2 mm×279.7 mm circuit patterns  30   a  formed thereon; 
     FIG. 6 is a flowchart showing an exemplary sequence of steps for scanning exposure; 
     FIG. 7 is a schematic view showing a size of the substrate holder  15   a;    
     FIG. 8 is a schematic view showing a substrate  200  loaded on the substrate holder  15   a ; and 
     FIG. 9 is a schematic view for illustrating a manner of printing six 17-inch SXGA LCD panels on a substrate by using a mask  100  that has two 279.7 mm×347.2 mm circuit patterns  101  formed thereon. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. 
     FIG. 1 is a schematic view showing an exemplary structure of a scanning-type exposure apparatus used in a method of the invention. The scanning-type exposure apparatus employs a step-and-scan system using a mask  10  which is smaller than a substrate  14  (a glass plate applied with a photosensitive agent such as a photoresist) to print a pattern drawn on the mask  10  on the substrate  14  for several times. Herein, an effective exposure area of the mask  10  is 400 mm×700 mm, and the size of the substrate  14  is 720 mm×900 mm. 
     An active matrix liquid crystal panel requires a plurality of pattern layers to be overlaid during the fabrication process in order to form active elements. Therefore, a plurality of masks are prepared which are used in turn for printing the overlaid patterns. 
     A light bundle emitted from a light source  1  such as an extra-high pressure mercury lamp is reflected off an oval mirror  2  and directed toward a dichroic mirror  3 . The dichroic mirror  3  reflects the light bundle in a wavelength range necessary for exposure and transmits the light bundle in other wavelength ranges. A shutter  4  arranged with respect to the optical axis AX 1  selectively controls the advance of the light bundle reflected off the dichroic mirror  3  to a following projection optical system. When the shutter  4  is open, the light bundle enters into a wavelength selection filter  5  which outputs a light bundle with a wavelength (usually, at least one of band ranges of G-, H- and I-lines) suitable for the projection optical system  12   a  to print. An intensity distribution of this light bundle is of a Gaussian type where intensity is the highest in the vicinity of the optical axis and becomes lower toward the periphery. Therefore, the intensity has to be made uniform at least within a projection region  13   a  made by the projection optical system  12   a . The intensity of the light bundle is made uniform with a flys&#39; eye lens  6  and a condenser lens  8 . A mirror  7  which bends the light is provided as a matter of device arrangement. 
     The light bundle with a uniformly-distributed intensity proceeds to a pattern plane of the mask  10  via a field stop  9 . The field stop  9  has an opening for defining the projection region  13   a  on the substrate  14 . Optionally, a lens system can be provided between the field stop  9  and the mask  10  such that the field stop  9 , the pattern plane of the mask  10  and a projection plane of the substrate  14  conjugate with each other. 
     The structure from the light source  1  to the field stop  9  is referred to as an illuminating optical system L 1  for the projection optical system  12   a . Herein, illuminating optical systems L 2  to L 5  having the same structure as the illuminating optical system L 1  are provided to supply light bundles to projection optical systems  12   b  to  12   e , respectively. Light bundles outcoming from the multiple illuminating optical systems L 1  to L 5  illuminate respective regions (illuminated areas)  11   a  to  11   e  on the mask  10 . The plurality of light bundles that passed through the mask  10  form pattern images of the illuminated areas  11   a  to  11   e  of the mask  10  on respective projection regions  13   a  to  13   e  of the substrate  14  via the projection optical systems  12   a  to  12   e  corresponding to the respective illuminating optical systems L 1  to L 5 . The projection optical systems  12   a  to  12   e  all form erect real images (erect normal images) at one to one magnification. In FIG. 1, the direction of optical axes of the projection optical systems  12   a  to  12   e  is referred to as Z-direction. The direction of scanning the mask  10  and the substrate  14  (perpendicular to the Z-direction) is referred to as X-direction (a first direction). The direction perpendicular to both Z- and X-directions is referred to as Y-direction (a second direction). 
     The substrate  14  is adsorbed (e.g., by vacuum holding) on the substrate holder  15   a  on a substrate stage  15 . According to this embodiment, the size of the rectangular substrate holder  15   a  is 843 mm×890 mm which is equivalent to the size of the prior art substrate holder shown in FIG.  7 . 
     The substrate stage  15  has an X-direction driving device  16 X which gives a long stroke along the scanning direction (X-direction) for one-dimensional scanning exposure. The substrate stage  15  also has a highly-accurate high-resolution X-direction position detecting device (e.g., a laser interferometer)  17 X with respect to the scanning direction. The mask  10  is supported by a mask stage  20  which, similar to the substrate stage  15 , also has an X-direction driving device  18 X which gives a long stroke along the scanning direction (X-direction) and an X-direction position detecting device  19 X for detecting the position of the mask stage  20  along the scanning direction. 
     Furthermore, the substrate stage  15  is capable of being step transferred in the Y-direction which is generally perpendicular to the X-direction (the scanning direction). Specifically, the substrate stage  15  is provided with a Y-direction driving device  16 Y for driving the substrate stage  15  in the Y-direction, and a Y-direction position detecting device  17 Y. The substrate stage  15  is step transferred by the Y-direction driving device  16 Y for a distance SP which is longer than the length of the illuminated areas  11   a  to  11   e  along the Y-direction. 
     FIG. 2 is a plan view showing a substrate  14  loaded on the substrate stage  15 . As shown in FIG. 2, the projection regions  13   a  to  13   c  on the substrate  14  are arranged such that regions adjacent along the Y-direction (e.g., regions  13   a  and  13   b , and regions  13   b  and  13   c ) are shifted for a predetermined length along the X-direction and the ends of the adjacent regions overlap along the Y-direction as represented by the dotted lines. Accordingly, in accordance with the projection regions  13   a  to  13   e , the multiple projection optical systems  12   a  to  12   e  are also shifted for a predetermined distance along the X-direction while the adjacent ends thereof overlap along the Y-direction. Although the shapes of the projection regions  13   a  to  13   e  are parallelograms in the figure, they may be hexagons, rhombuses, trapezoids or the like. The multiple illuminating optical systems L 1  to L 5  are arranged such that the illuminated areas  11   a  to  11   e  on the mask  10  match with the above-described projection regions  13   a  to  13   e . The substrate  14  is provided with alignment marks (substrate marks)  24   a ,  24   b ,  24   c , . . . ,  24   f ,  24   g ,  24   h , . . . ,  24   p ,  24   q ,  24   r , . . . outside the exposure areas  14   a ,  14   b ,  14   c  and  14   d.    
     FIG. 3 is a plan view of the mask  10  showing a pattern region  10   a  having a pattern to be printed on the substrate  14 . Outside the pattern region  10   a , the mask  10  is provided with alignment marks (mask marks)  23   a  to  23   j  corresponding to the substrate marks  24   a ,  24   b ,  24   c , . . . ,  24   f ,  24   g ,  24   h , . . . ,  24   p ,  24   q ,  24   r , . . . on the substrate  14 . 
     As can be appreciated from FIGS. 1 and 3, the alignment systems  20   a  and  20   b  are provided above the mask  10 , for detecting the mask marks  23   a  to  23   j  on the mask  10  as well as the substrate marks  24   a ,  24   b ,  24   c , . . . ,  24   f ,  24   g ,  24   h , . . . ,  24   p ,  24   q ,  24   r , . . . formed on the substrate  14 , via the projection optical systems  12   a  and  12   e . Specifically, light beams outcoming from the alignment systems  20   a  and  20   b  are directed toward the mask marks  23   a  to  23   j  formed on the mask  10  via the reflecting mirrors  25   a  and  25   b , and toward the substrate marks  24   a ,  24   b ,  24   c , . . . ,  24   f ,  24   g ,  24   h , . . . ( 24   f ,  24   g ,  24   h , . . . ,  24   p ,  24   q ,  24   r , . . . ) on the substrate  14  via the optical systems  12   a  and  12   e  at both ends of the multiple projection optical systems  12   a  to  12   e.    
     The light reflected off the substrate marks  24   a ,  24   b ,  24   c , . . . ,  24   f ,  24   g ,  24   h , . . . ( 24   f ,  24   g ,  24   h , . . . ,  24   p ,  24   q ,  24   r , . . . ) formed on the substrate  14  is directed to the alignment systems  20   a  and  20   b  via the projection optical systems  12   a  and  12   e  and the reflecting mirrors  25   a  and  25   b . The light reflected off the mask marks  23   a  to  23   j  formed on the mask  10  is directed to the alignment systems  20   a  and  20   b  via the reflecting mirrors  25   a  and  25   b . The alignment systems  20   a  and  20   b  detect the position of each alignment mark based on the reflected light from the mask  10  and the substrate  14 . 
     While transferring the mask stage  20  and the substrate stage  15  along the X-direction, the alignment detection systems  20   a  and  20   b  simultaneously detect the substrate marks  24   a ,  24   b ,  24   c , . . . ,  24   f ,  24   g ,  24   h , . . . (  24   f ,  24   g ,  24   h , . . . ,  24   p ,  24   q ,  24   r , . . . ) on the substrate  14  and the mask marks  23   a  to  23   j  on the mask  10 , thereby detecting the relative positions of the substrate  14  and the mask  10 . 
     The scanning-type exposure apparatus is capable of step transferring the substrate stage  15  along the Y-direction (which is generally perpendicular to the X-direction, or the scanning direction) for a distance SP which is at least longer than the width of the illuminated areas  11   a  to  11   e  along the Y-direction. After the scanning exposure by synchronously driving the mask stage  20  and the substrate stage  15  along the X-direction, the scanning exposure is performed once more or for several times by step transferring the substrate stage  15  along the Y-direction for a distance SP to print an array of multiple mask patterns  10   a  onto the large substrate  14 . 
     Returning to FIG. 1, the controller  50  controls the whole scanning-type exposure apparatus, and is input with the measurement results from the position detecting devices  17 X,  17 Y and  19 X as well as alignment outputs from the alignment systems  20   a  and  20   b . The controller  50  is provided with a storage medium  51 . 
     Hereinafter, a method will be described for exposing the substrate  14  to six 17-inch SXGA patterns, each having a size of 279.7 mm×347.2 mm including a circuit pattern surrounding a pixel region. 
     As described above, the size of the substrate holder  15   a  is 843 mm×890 mm and the size of the substrate  14  is 720 mm×900 mm, where the longer sides of the substrate  14  are longer than the shorter sides of the substrate holder  15   a . Moreover, instead of the mask  10 , a mask  30  is used which is printed with two 17-inch SXGA patterns  30   a . The effective exposure area of the mask  30  is 400 mm×700 mm which is the same as that of the mask  10 . The mask  30  is provided with mask marks (omitted in the figure) similar to those on the mask  10 . 
     FIG. 4 is a schematic plan view showing a substrate  14  supported by the substrate holder  15   a  (which is represented by dotted lines in FIG. 4 for distinction from the substrate  14 ). 
     As shown in FIG. 4, in order to expose the substrate  14  to the 17-inch SXGA patterns, the substrate  14  is loaded on the substrate holder  15   a  such that the longer sides of the substrate  14  are in parallel to the shorter sides of the substrate holder  15   a  (i.e., the substrate  14  is rotated by 900 from the position shown in FIG.  1 ). 
     Although the ends of the longer sides of the substrate  14  project out from the substrate holder  15   a , the exposure areas  14   a  to  14   f  of the substrate  14  are supported by (in contact with) the substrate holder  15   a  via the above-described vacuum holding. Since the flatness of the exposure areas  14   a  to  14   f  of the substrate  14  is precisely maintained by vacuum holding, the patterns  30   a  of the mask  30  can accurately be printed onto the exposure areas  14   a  to  14   f  of the substrate  14 . Although they are not shown in the figure, alignment marks are formed on the substrate  14  at positions corresponding to the vacuum holding regions of the substrate holder  15   a  for alignment of the substrate  14 . 
     FIG. 5 is a schematic plan view showing a method for printing six 17-inch SXGA panels on the substrate  14 , by using a mask  30  that has two 347.2 mm×279.7 mm circuit patterns  30   a  formed thereon. In FIG. 5, the substrate holder  15   a  is omitted. 
     As shown in FIG. 5, the size of the mask  30  is the same as that of the prior art mask  100 , although the direction of the pattern  30   a  is shifted by 900 from that of the pattern  101  of the mask  100 . In other words, the longer sides of the pattern  30   a  of the mask  30  are in parallel to the longer sides of the mask  30 . 
     Hereinafter, an exemplary sequence of steps for scanning exposure with the controller  50  will be described with reference to the flowchart shown in FIG.  6 . 
     The controller  50  controls a mask loader (not shown) to replace the mask  10  on the mask stage  20  with the mask  30  which is provided with two 17-inch SXGA patterns  30   a  (Step  20 ). 
     When the answer in Step  20  is “YES”, the controller  50  proceeds to Step  21  to align the mask  30  with respect to the exposure apparatus, using the alignment systems  20   a  and  20   b  supported by a supporting member supporting the projection optical systems  12   a  to  12   e . The alignment systems  20   a  and  20   b  perform the alignment by adjusting the position of the mask stage  20  such that the positions of the mask marks are in a predetermined relationship with the index marks in the alignment systems  20   a  and  20   b  (Step  21 ). When there is no need of replacing the mask, Step  21  is omitted. 
     Next, the controller  50  loads the substrate  14  that is to be exposed onto the substrate holder  15   a  on the substrate stage  15  by using a substrate loader (not shown), and positions the loaded substrate  14  with respect to the exposure apparatus such that the longer sides of the substrate  14  are in parallel to the shorter sides of the substrate holder  15   a  (Step  22 ). Specifically, similar to the alignment of the mask  30  at Step  21 , the substrate stage  15  is driven by detecting the substrate marks with the alignment systems  20   a  and  20   b  such that the positions of the substrate marks are in a predetermined relationship with the index marks in the alignment systems  20   a  and  20   b.    
     The controller  50  synchronously scans the mask  30  and the substrate  14  with respect to the projection optical systems  12   a  to  12   e  by driving the mask stage  20  and the substrate stage  15 , for example, in the −X-direction, by the X-direction driving device  18 X for the mask stage  20  and the X-direction driving device  16 X for the substrate stage  15 . One of the alignment systems  20   a  and  20   b  detects relative positions of the mask marks and the substrate marks upon synchronous scanning. The relative positions of the detected mask marks and the substrate marks upon synchronous scanning are stored in the storage medium  51  (Step  23 ). 
     After the mask  30  and the substrate  14  are scanned, the mask  30  and the substrate  14  are aligned at the scan initiating positions where the mask  30  and the substrate  14  are completely dislocated from the illuminated areas  11   a  to  11   e  and the projection regions  13   a  to  13   e , respectively (Step  24 ). The alignment at Step  24  is performed by calculating, by the least square method, the transportation distances of the mask  30  in the X-direction, Y-direction and the rotation direction such that the relative position errors between the mask marks and the corresponding substrate marks (which are detected during the scanning at Step  23  and stored in the storage medium  51 ) are minimum, and in accordance with the results, by adjusting the position of the mask  30  on the mask stage  20 . 
     The controller  50  prints the two patterns  30   a  of the mask  30  on the projection regions  14   a  and  14   b  of the substrate  14  as represented by the arrow  1  in FIG. 5 by the first scanning exposure where the mask stage  20  and the substrate stage  15  are synchronously scanned in the +X-direction (Step  25 ). 
     After the first scanning exposure, the controller  50  drives the Y-direction driving device  16 Y to stepwisely transport the substrate  14  in the Y-direction. The distance of a single step transportation is generally equal to the length of the shorter side of the 17-inch SXGA LCD panel (279.7 mm in the figure) (Step  26 ). 
     The controller  50  prints the two patterns  30   a  of the mask  30  on the projection regions  14   c  and  14   d  of the substrate  14  as represented by the arrow  2  in FIG. 5 by the second scanning exposure where the mask stage  20  and the substrate stage  15  are synchronously scanned in the −X-direction (Step  27 ). 
     After the second scanning exposure, the controller  50  drives the Y-direction driving device  16 Y to stepwisely transport the substrate  14  in the Y-direction. The distance of a single step transportation is the same as Step  26  and is generally equal to the length of the shorter side of the 17-inch SXGA LCD panel (279.7 mm in the figure) (Step  28 ). 
     The controller  50  prints the two patterns  30   a  of the mask  30  on the projection regions  14   e  and  14   f  of the substrate  14  as represented by the arrow  3  in FIG. 5 by the third scanning exposure where the mask stage  20  and the substrate stage  15  are synchronously scanned in the +X-direction (Step  25 ). 
     When six 17-inch SXGA LCD panels are to be printed, the prior art required scanning exposures for four times. On the other hand, according to the embodiment of the present invention, six 17-inch SXGA LCD panels can be printed by scanning exposures for three times since the substrate  14  is loaded on the substrate holder  15   a  such that the longer sides of the substrate  14  are arranged in parallel to the shorter sides of the substrate holder  15   a.    
     In order to simplify the description of the present embodiment, the sizes of the mask  30 , the substrate  14  and the substrate holder  15   a  are specialized herein. The present embodiment, however, is not limited to these sizes and can broadly be applied to devices of various sizes as long as the substrate holder  15   a  is loaded on the substrate  14  such that the longer sides of the substrate  14  are arranged in parallel to the shorter sides of the substrate holder  15   a.    
     According to the present invention, scanning exposure can be carried out with reduced number of scanning steps and at enhanced throughput without enlarging the exposure apparatus including a substrate holder, by allowing a substrate to be placed with respect to the substrate holder such that the longer sides of the substrate are in parallel to the shorter sides of the substrate holder depending on the size of the apparatus and the size of the substrate.