Abstract:
A grating member comprising a diffraction grating having a periodic structure for converting an incident wavefront at the central area into a prescribed wavefront is provided with a light-shielding member comprising a UV-light absorbing material at the periphery of the grating member in order to reduce excess light and scattered light.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an optical element, to a diffractive optical element and other optical systems having these elements, which are suitable for, for example, an imaging optical system to be used for a camera for forming an image of a photographic subject on a surface of a photosensitive material, an image forming optical system for forming image information on a photosensitive drum by optically scanning the surface of the drum, a projection optical system for projecting electronic circuit patterns on a mask as a first photographic subject on a wafer as a second photographic subject using the projection optical system such as a projection lens for producing a device like a semiconductor element such as an IC and LSI, and an illumination optical system for illuminating the mask for projection as described above.  
           [0003]    2. Description of the Related Art  
           [0004]    A variety of optical systems using diffractive optical elements employing light diffraction phenomenon have been proposed in recent years. Examples of diffractive optical elements known in the art include Fresnel zone plates, kinoforms, binary optics, and holograms.  
           [0005]    Diffractive optical elements are used as optical elements for converting an incident wavefront into a prescribed wavefront. These diffractive optical elements have characteristics that are not found in refractive optical elements. For example, diffractive optical elements have characteristics such as inverse dispersion of the reflective optical elements and the optical system can be compact since the element has substantially no thickness.  
           [0006]    Generally speaking, semiconductor manufacturing techniques can be applied for producing diffractive optical elements when it assumes, for example, a binary type configuration, making it possible to relatively easily realize fine pitches. Accordingly, studies on binary type diffractive optical elements in which a blazed configuration is approximated by a stepped structure have been aggressively pursued in recent years.  
           [0007]    [0007]FIG. 22 to FIG. 24 show illustrative drawings of the main portions of conventional diffractive optical elements.  
           [0008]    [0008]FIG. 22 shows a Fresnel zone plate, in which a light-shielding member where metallic film is to remain and light-transparent portions where no film is to remain is formed by printing the Fresnel zone by a lithographic process after depositing a metallic film such as a chromium film on a glass substrate. FIG. 23 shows a cross section of a Fresnel lens (kinoform) in which each of the annular periodic patterns along the radius direction follows a continuously curved surface that is formed by cutting or press work. FIG. 24 shows a binary type diffractive optical element comprising a phase difference type diffraction grating machined into steps by repeating plural lithographic processes on the surface of a glass substrate.  
           [0009]    [0009]FIG. 25 to FIG. 27 show a cross section of the main part of an optical barrel having a conventional diffractive optical element.  
           [0010]    In FIG. 25, the diffractive optical element  2501  is inserted into the barrel  2502 , the diffractive optical element  2501  having approximately the same effective aperture as that of the barrel  2502 . In FIG. 26, the diffractive optical element  2601  is also inserted into the lens barrel  2602  as shown in FIG. 25, the diffractive optical element  2601  having a larger effective aperture than that of the barrel  2602 . As shown in FIG. 27, the periphery of the diffractive optical element  2701  is shaved off close to the vicinity of the circumference where the element serves as a diffractive optical element. The reference numeral  2702  denotes the barrel.  
           [0011]    Meanwhile, stray light is generated when the light incident on the diffractive optical element impinges on the area outside the diffraction grating, deteriorating optical characteristics.  
           [0012]    Accordingly, Japanese Patent Laid-Open Nos. 62-250401 and 4-95233 propose a diffractive optical element in which a light-shielding film is provided outside of the effective area of the diffraction grating.  
           [0013]    Various advantages as described above can be obtained when the diffractive optical element is used as a part of the optical system. However, it is difficult, for example, in the diffractive optical element shown in FIG. 25 to assemble it by fitting its effective aperture with the effective aperture of the barrel to leave a portion having no diffraction properties of the diffractive optical element within the effective aperture of the barrel, causing excessive light A to be generated. When the effective aperture of the diffractive optical element is made to be larger than the effective aperture of the barrel as shown in FIG. 26, on the other hand, a problem was encountered in that an excess machining cost was incurred for EB painting of the mask required for machining of the peripheral portion where no light beam should pass through. In addition, fine dust and foreign matter adhere in the diffractive optical element unit, as shown in FIG. 27, since cutting of the portions close to the diffraction grating is required, also causing scattering to occur.  
           [0014]    Accordingly, there was a problem in that good quality of diffractive optical elements and optical systems using the optical elements cannot be manufactured because excessive light and scattered light are generated in all the conventional diffractive optical elements.  
           [0015]    While stray light is prevented from being generated in the diffractive optical element proposed in Japanese Patent Laid-Open Nos. 62-250401 and 4-95233 cited above by providing a light-shielding film at the periphery of the effective area, detailed constructions of the light-shielding films are not disclosed.  
           [0016]    A proper choice of this sort of light-shielding material is crucial, otherwise undesirable substances may be generated from the material by UV irradiation or when gas emitted from the material is decomposed by UV light to generate undesirable substances that fog the lens, thereby shortening the service life of the exposure apparatus. A light-shielding member which is directly exposed to the light is particularly susceptible.  
         SUMMARY OF THE INVENTION  
         [0017]    Accordingly, an object of the present invention is to provide a diffractive optical element that does not generate any excessive light or scattered light by properly selecting the light-shielding member constituting the optical elements such as a diffractive optical element and is readily manufactured while maintaining good optical performance, and an optical system using the element.  
           [0018]    According to the present invention, a light-shielding member comprising a ceramic or a metal that does not generate any undesirable substances by UV irradiation is provided at the periphery of an optical element such as a lens, mirror, and diffractive optical element.  
           [0019]    Another optical element according to the present invention is provided with an effective area and a light-shielding area in the periphery of the effective area, the light-shielding area shielding UV-laser light with a wavelength of 250 nm or less while generating no undesirable substances due to the laser light.  
           [0020]    Another optical element according to the present invention is provided with an effective area and a light-shielding area in the periphery of the effective area, the light-shielding area shielding UV light while generating no undesirable substances due to the UV light.  
           [0021]    Another optical element according to the present invention is provided with an effective area and a light-shielding area in the periphery of the effective area, the light-shielding area shielding radiation energy while generating no undesirable substances due to the radiation energy.  
           [0022]    Another optical element according to the present invention is provided with an effective area and a light-shielding area in the periphery of the effective area, the light-shielding area shielding UV laser light with a wavelength of 250 nm or less while being resistant to the laser light.  
           [0023]    Another optical element according to the present invention is provided with an effective area and a light-shielding area in the periphery of the effective area, the light-shielding area shielding UV light while being resistant to the UV light.  
           [0024]    Another optical element according to the present invention is provided with an effective area and a light-shielding area in the periphery of the effective area, the light-shielding area shielding radiation energy while being resistant to the radiation energy.  
           [0025]    The optical element is provided with a light-shielding member comprising an inorganic material at the periphery of an optical element.  
           [0026]    The material of the optical element comprises a thin film ceramic.  
           [0027]    The material of the optical element comprises at least one of TiC, TiN, ZrC, ZrN, HfC and HfN.  
           [0028]    The material of the optical element comprises metallic materials.  
           [0029]    The material of the optical element comprises a metal subjected to reflection preventive treatment.  
           [0030]    The material of the optical element comprises at least one of chromium, aluminum, molybdenum, tantalum and tungsten.  
           [0031]    The reflection preventive treatment of the optical element comprises a laminated structure of a metal oxide layer on the light-shielding member.  
           [0032]    The metal oxide layer of the optical element comprises at least one of silicon oxide and aluminum oxide.  
           [0033]    The material of the optical element comprises a compound of a metal and silicon.  
           [0034]    The material of the optical element comprises a compound of at least one of molybdenum and tungsten, and silicon.  
           [0035]    The material of the optical element comprises a semiconductor material.  
           [0036]    The material of the optical element comprises silicon.  
           [0037]    The material of the light-shielding member in the optical element comprises a metal oxide.  
           [0038]    The present invention has a light-shielding member composed of a metal subjected to an anti reflection treatment, the light-shielding member composed of a low reflection chromium film, or a multi-layer film of a chromium oxide and metallic chromium; a diffraction grating formed at the central area of the optical element, the ceramic material composed of either TiC, TiN, ZrC, ZrN, HfC or HfN, or a combination thereof, the ceramic material absorbing light of a wavelength to be used; an alignment mark provided on the light-shielding member; a light-shielding member comprising a metal and an alignment mark provided at the periphery of the optical element; the light-shielding member and the alignment mark provided by printing; and the portions where the light-shielding ink to be used for printing is illuminated with the light to be used does not protrude. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0039]    [0039]FIG. 1A and FIG. 1B show cross sections of the main part of the diffractive optical element in the first embodiment according to the present invention.  
         [0040]    [0040]FIG. 2 shows an illustrative drawing of the diffractive optical element according to the present invention in a manufacturing step in the first embodiment.  
         [0041]    [0041]FIG. 3 shows an illustrative drawing of the diffractive optical element according to the present invention in a manufacturing step in the first embodiment.  
         [0042]    [0042]FIG. 4 shows an illustrative drawing of the diffractive optical element according to the present invention in a manufacturing step in the first embodiment.  
         [0043]    [0043]FIG. 5 shows an illustrative drawing of the diffractive optical element according to the present invention in a manufacturing step in the first embodiment.  
         [0044]    [0044]FIG. 6 shows an illustrative drawing of the diffractive optical element according to the present invention in a manufacturing step in the first embodiment.  
         [0045]    [0045]FIG. 7 shows an illustrative drawing of the diffractive optical element according to the present invention in a manufacturing step in the first embodiment.  
         [0046]    [0046]FIG. 8 shows an illustrative drawing of the diffractive optical element according to the present invention in a manufacturing step in the first embodiment.  
         [0047]    [0047]FIG. 9 shows an illustrative drawing of the diffractive optical element according to the present invention in a manufacturing step in the first embodiment.  
         [0048]    [0048]FIG. 10 shows an illustrative drawing of the diffractive optical element according to the present invention in a manufacturing step in the second embodiment.  
         [0049]    [0049]FIG. 11 shows an illustrative drawing of the diffractive optical element according to the present invention in a manufacturing step in the second embodiment.  
         [0050]    [0050]FIG. 12 shows an illustrative drawing of the diffractive optical element according to the present invention in a manufacturing step in the second embodiment.  
         [0051]    [0051]FIG. 13 shows an illustrative drawing of the diffractive optical element according to the present invention in a manufacturing step in the second embodiment.  
         [0052]    [0052]FIG. 14 shows an illustrative drawing of the diffractive optical element according to the present invention in a manufacturing step in the second embodiment.  
         [0053]    [0053]FIG. 15 shows an illustrative drawing of the diffractive optical element according to the present invention in a manufacturing step in the second embodiment.  
         [0054]    [0054]FIG. 16 shows an illustrative drawing of the diffractive optical element according to the present invention in a manufacturing step in the second embodiment.  
         [0055]    [0055]FIG. 17A and FIG. 17B show outlines of the main part of the diffractive optical element in the third embodiment according to the present invention.  
         [0056]    [0056]FIG. 18A and FIG. 18B show outlines of the main part of the diffractive optical element in the third embodiment according to the present invention.  
         [0057]    [0057]FIG. 19A and FIG. 19B show outlines of the main part of the diffractive optical element in the fifth embodiment according to the present invention.  
         [0058]    [0058]FIG. 20A and FIG. 20B show outlines of the main part of the diffractive optical element in the ninth embodiment according to the present invention.  
         [0059]    [0059]FIG. 21 shows an outline of the main part of the optical system using the diffractive optical element in the 10th embodiment according to the present invention.  
         [0060]    [0060]FIG. 22 shows an illustrative drawing of the diffractive optical element in the related art.  
         [0061]    [0061]FIG. 23 shows an illustrative drawing of the diffractive optical element in the related art.  
         [0062]    [0062]FIG. 24 shows an illustrative drawing of the diffractive optical element in the related art.  
         [0063]    [0063]FIG. 25 shows an illustrative drawing of the diffractive optical element in the related art.  
         [0064]    [0064]FIG. 26 shows an illustrative drawing of the diffractive optical element in the related art.  
         [0065]    [0065]FIG. 27 shows an illustrative drawing of the diffractive optical element in the related art.  
         [0066]    [0066]FIG. 28 is an illustrative drawing of the main part in the eleventh embodiment of the diffractive optical element according to the present invention.  
         [0067]    [0067]FIG. 29 is an illustrative drawing of the main part in the eleventh embodiment of the diffractive optical element according to the present invention.  
         [0068]    [0068]FIG. 30 is an illustrative drawing of the main part in the eleventh embodiment of the diffractive optical element according to the present invention.  
         [0069]    [0069]FIG. 31 is an illustrative drawing of the eleventh embodiment according to the present invention.  
         [0070]    [0070]FIG. 32 is an illustrative drawing of the eleventh embodiment according to the present invention.  
         [0071]    [0071]FIG. 33 is an illustrative drawing of the eleventh embodiment according to the present invention.  
         [0072]    [0072]FIG. 34 is an illustrative drawing of the eleventh embodiment according to the present invention.  
         [0073]    [0073]FIG. 35 is an illustrative drawing of the eleventh embodiment according to the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0074]    [0074]FIG. 1A and FIG. 1B show a front view and cross section, respectively, of the main part in the first embodiment of the optical barrel having the diffractive optical element according to the present invention. In the drawing, the reference numeral  1  denotes a diffractive optical element having a grating member  101  provided with a diffraction grating with a binary shaped (stepped shaped), kinoform shaped, or frennel shaped cross section and a light-shielding member  103  provided at the face side where the diffraction grating  101  is formed at a given width in the optically non-effective area around the periphery of the diffraction grating  101 . The reference numeral  102  denotes a barrel (a holding frame) holding the diffractive optical element  1 .  
         [0075]    The letter φ, d, and D denote an effective aperture size of the grating member  101  of the diffractive optical element  1 , an aperture size of the diffractive optical element  1  and an aperture size of the barrel  102 , respectively. Although the present embodiment refers to a transmission type diffractive optical element  1  through which the incident light within the area of the aperture passes through, it may represent a reflection type diffractive optical element  1  having a reflection film within the area for reflecting the incident light within the aperture.  
         [0076]    The method for manufacturing the diffractive optical element  1  according to the present invention will be described hereinafter referring to FIG. 2 through FIG. 9. A so-called lithographic technique is used for the manufacturing method described above.  
         [0077]    In this embodiment, a low-reflection chromium layer as a material of the light-shielding member is formed on the substrate, followed by manufacturing the diffractive optical element having a diffraction grating comprising four steps.  
         [0078]    The low-reflection black chromium layer  205  is composed of a chromium layer and a chromium oxide layer, the black chromium layer comprising two layers of the chromium layer and chromium oxide layer or the chromium oxide layer and chromium layer, or three layers in which the chromium layer  203  is inserted between the chromium oxide layers  202  and  204 . The layer construction of the light-shielding member is selected depending on the requirement for lowering the reflection. The three layered construction will be described in this embodiment.  
         [0079]    As shown in FIG. 2, the chromium oxide (CrO x ) film  202  with a thickness of 300 Å is first deposited by sputtering on a transparent quartz substrate  201 , followed by depositing the chromium (Cr) film  203  at a thickness of 1000Å by sputtering. The chromium oxide (CrO x ) film  204  with a thickness of 300 Å is further deposited on the above two films.  
         [0080]    An alignment mark  301  as a reference point for the subsequent alignment is formed on a part of the low reflection chromium layer  205 . For this purpose, the chromium oxide film  204  is removed by a reactive ion etching method after allowing the low reflection chromium layer to be exposed solely at the portion where the alignment mark is formed by spin-coating a photoresist. An etching gas such as chlorine gas or a mixed gas of chlorine gas and oxygen gas is used for etching. Over-etching may be permitted provided that the chromium layer remains. The photoresist is then peeled off in the next step. FIG. 3 shows an illustrative drawing after applying the foregoing steps.  
         [0081]    Then, the photoresist is spin-coated to form a pattern (a resist pattern)  401  on only the portion to serve as the light-shielding member  103  so that the low-reflection chromium film does not protrude. FIG. 4 shows an illustrative drawing after this step. The upper chromium oxide layer  204 , the intermediate chromium layer  203  and the lower chromium layer  202  are removed by a reactive ion-etching. An etching gas such as chlorine gas or a mixed gas of chlorine gas and oxygen gas is used for etching. Subsequently, the photoresist  401  is peeled off. FIG. 5 shows an illustrative drawing after this step.  
         [0082]    Next, an etching step of the grating member  101  is carried out.  
         [0083]    A photoresist is coated on the substrate  201  as shown in FIG. 5 to form a first resist pattern  601 . FIG. 6 shows an illustrative drawing after the above step. The quartz substrate  201  is subsequently etched to a depth of 2440 Å using the resist pattern  601  as a mask, followed by peeling the resist pattern  601 . Then, the photoresist is coated on the substrate  201  to form a second resist pattern  701 . FIG. 7 shows an illustrative drawing after the above step. Subsequently, the quartz substrate  201  is subsequently etched to a depth of 1220 Å using the resist pattern  701  as a mask. FIG. 8 shows an illustrative drawing after the above step. Finally, the photoresist pattern  701  is peeled to manufacture the diffractive optical element having the light-shielding member as shown in FIG. 9 on the diffraction face. The remaining work is only to insert the refractive optical element  1  into the barrel  102  and the like as shown in FIG. 1. When a highly precise centering between the barrel  102  and refractive optical element  1  is required, centering between the barrel  102  and refractive optical element  1  is simplified by taking advantage of the alignment mark  301  used in the process for mounting in the lens barrel  102 .  
         [0084]    When a member composed of a metal such as the low reflection chromium or a combination thereof with an inorganic material is used, the gas emitted due to light irradiation is reduced, resulting in no fogging of the lens, increasing the service of the instrument.  
         [0085]    The method for manufacturing the refractive optical element in the second embodiment according to the present invention will be described hereinafter referring to FIG. 10 through FIG. 16.  
         [0086]    While the light-shielding member is made of the low reflection chromium film as in the first embodiment, the light-shielding member is formed after manufacturing the diffractive optical element having the diffraction grating comprising four steps in the manufacturing method according to this embodiment. FIG. 10 through FIG. 16 show a stage of the manufacturing method in this embodiment.  
         [0087]    A photoresist is coated on a quartz substrate  1001  to form a first resist pattern  1002 . A resist pattern  1003  for the alignment mark to serve as a reference point for the succeeding steps is simultaneously formed. FIG. 10 shows an illustrative drawing after the above steps. Then, the quartz substrate  1001  is subsequently etched to a depth of 2440 Å using the resist pattern  1002  as a mask. FIG. 11 shows an illustrative drawing after the above steps. Then, a photoresist is coated on the substrate  1001  to form a second resist pattern  1204 . Subsequently, the quartz substrate  1001  is etched to a depth of 1220 Å using the resist pattern  1204  as a mask. FIG. 12 shows an illustrative drawing after the above steps. Finally, the photoresist pattern  1204  is peeled to complete the diffractive optical element  1  as shown in FIG. 13.  
         [0088]    In the next step, a chromium oxide (CrO x ) film  1405  with a thickness of 300 Å is deposited on the substrate  1001  shown in FIG. 13 by sputtering, followed by depositing a chromium (Cr) film  1406  with a thickness of 1000 Å by sputtering. Subsequently, a chromium oxide (CrO x ) film  1407  with a thickness of 300 Å is deposited by sputtering. FIG. 14 shows an illustrative drawing after the above steps.  
         [0089]    Then, a pattern  1501  is formed by spin-coating the photoresist so that only the light-shielding member  103  is masked. FIG. 15 shows an illustrative drawing after the above steps.  
         [0090]    The upper chromium oxide layer  1407 , the intermediate chromium layer  1406  and the lower chromium oxide layer  1405  coated on the grating member area are removed by a reactive ion-etching method. An etching gas such as chlorine gas or a mixed gas of chlorine gas and oxygen gas is used for etching. The photoresist  1501  is subsequently peeled off. FIG. 16 shows an illustrative drawing after the above steps. The refractive optical element  1  having a light-shielding member  103  on the refraction face is thus manufactured by the steps as described above.  
         [0091]    The remaining manufacturing step is merely to insert the refractive optical element  1  into the barrel  102  and the like as shown in FIG. 1. When a highly precise centering between the barrel  102  and refractive optical element  1  is required, centering between the barrel  102  and refractive optical element  1  is simplified by taking advantage of the alignment mark  301  used in the process for mounting the lens barrel  102 .  
         [0092]    [0092]FIG. 17A and FIG. 17B show a front view and cross section, respectively, of the main part of the optical barrel according to the third embodiment having the diffractive optical element according to the present invention.  
         [0093]    The present embodiment differs from the first embodiment illustrated in FIG. 1A and FIG. 1B in that a light-shielding member  1703  with a given width is provided around a face opposing the face on which a refraction grating  1701  of the substrate of the diffractive optical element  1  is provided, the other construction being the same. The reference numeral  1702  in the drawing denotes a barrel (a holding frame).  
         [0094]    This embodiment is effective when the thickens of the substrate of the diffractive optical element  1  is thin or the pupil of the optical system is disposed in the vicinity of the diffractive optical element. Light-shielding members may be provided in the peripheries of both faces.  
         [0095]    The steps of sputtering, coating resists, patterning, etching, and peeling resists, as shown in FIG. 2 through FIG. 5 in the first embodiment, are also applied on the back face of the substrate in the method for manufacturing the diffractive optical element according to this embodiment. The steps may be carried out either before or after processing of the refraction face when the processing steps do not damage the front diffraction face. The center of the diffraction face on the front face and the center of the light-shielding face on the back face can be aligned with good precision by using a dual face exposure apparatus equipped with a dual face alignment mechanism such as the apparatus sold by Karl Zeiss Co. under the trade name “Suss MA25”.  
         [0096]    The remaining manufacturing step is merely to mount the refractive optical element  1  in the barrel  1702  and the like as shown in FIG. 17. When a highly precise centering between the barrel and refractive optical element is required, centering between the barrel and refractive optical element is simplified by taking advantage of the alignment mark used in the process for mounting in the barrel.  
         [0097]    [0097]FIG. 18A and FIG. 18B denote the cross sections of the main part of the lens barrel having the refractive optical element in the fourth embodiment according to the present invention. FIG. 8A is an exploded drawing to facilitate understanding of the constructions of respective elements denoted by the reference numerals  1801 ,  1802 , and  1804 .  
         [0098]    The present embodiment differs from the first embodiment illustrated in FIG. 1A and FIG. 1B in that two independent members of a grating member  1801  provided with a diffraction grating and an optical element  1804  having a light-shielding member  1803  for shielding the incident light to the periphery of the grating member  1801  are disposed in adjoining relation with each other in the diffractive optical element  1 , the other construction being the same.  
         [0099]    When the grating member  1801  is manufactured by machining the diffraction grating over a wide area on a thin substrate  1805  in the present embodiment, tare deformation by weight of the grating member  1801  is diminished by laminating the optical elements  1804  comprising parallel plates with each other. This processing also serves to protect the diffraction face. A laminated hybrid type diffractive or refractive optical element may be used for the optical element  1804  by allowing it to have a curvature.  
         [0100]    For manufacturing the parallel plates  1804  having the light shielding member  1803 , the steps of sputtering, coating resists, patterning, etching, and peeling resists, as shown in FIG. 2 through FIG. 5 in the first embodiment, are applied to the parallel plates. As shown in FIG. 3, the optical axis of the diffractive optical element of the grating member  1801  can be aligned with a high precision to the center of the light-shielding member  1803  of the parallel plates  1804  by providing an alignment mark on the light-shielding member  1803  to laminate the parallel plates  1804  by aligning the foregoing alignment mark with the alignment mark on the grating member  1801 .  
         [0101]    The remaining manufacturing step is merely to insert the refractive optical element  1  in the barrel  1802  and the like as shown in FIG. 18. When a highly precise centering between the lens barrel  1802  and refractive optical element  1  is required, centering between the lens barrel and refractive optical element is simplified by taking advantage of the alignment mark used in the process for mounting the lens barrel.  
         [0102]    [0102]FIG. 19A and FIG. 19B show cross sections of the main part of the optical barrel having the diffractive optical element in the fifth embodiment according to the present invention. FIG. 19A denotes an exploded drawing as shown in FIG. 18A.  
         [0103]    The present embodiment differs from the fist embodiment shown in FIG. 1A and FIG. 1B in that the diffractive optical element  1  is composed of three members of a grating member  1901  provided with a diffraction grating, an optical element  1904  comprising parallel plates and a light-shielding member  1903  for shielding the incident light to the periphery of the grating member  1901  disposed between them, the remaining constructions being the same. The reference numeral  1902  denotes a barrel (a holding member).  
         [0104]    When the grating member  1901  is manufactured by machining the diffraction grating over a wide area on a thin substrate  1905  in the present embodiment, tare deformation by weight of the grating member  1901  is diminished by laminating the optical elements  1904  comprising parallel plates with each other. This processing also serves to protect the diffraction face. A laminated hybrid type diffractive or refractive optical element is provided for the optical elements  1904  by allowing it to have a spherical or non-spherical curvature.  
         [0105]    The light-shielding member  1903  is composed of an inorganic matter, such as metallic thin plate treated to form a black anodized aluminum, a thin plate of an absorbing member comprising a black inorganic ceramic material, or a ring-shaped thin-plate perforated at the center of the metallic thin plate subjected to a surface matte processing.  
         [0106]    The diffractive optical element  1  as shown in FIG. 19B is constructed by laminating the grating member  1901  with the light-shielding member  1903  by centering their optical axes by taking advantage of the alignment mark provided when perforating the light-shielding member  1903 , the parallel plates  1904  being further laminated thereon to insert the entire diffractive optical element  1  in the barrel.  
         [0107]    The sixth embodiment of the diffractive optical element according to the present invention will be described hereinafter.  
         [0108]    The diffraction optical element according to the present embodiment differs from the diffraction optical element  1  shown in FIG. 1A and FIG. 1B in that the light-shielding member  103  of the diffraction optical element  1  is provided by printing and the other constructions are the same as in the first embodiment in FIG. 1A and FIG. 1B. The light-shielding member is provided by printing on the substrate  1001  formed via the steps shown in FIG. 10 through FIG. 13 using the alignment mark as a reference point. The printing methods include a screen printing, a tampon printing, and hot-stump printing in which an acrylic or epoxy light-shielding ink is printed at a thickness of several to several tens of microns.  
         [0109]    The portions where the ink is coated and is not coated are divided into the portions where the screen is soaked and not soaked with the ink on the screen in the screen printing, and the ink is transferred through the screen. The ink is absorbed in a silicon rubber in the tampon printing to transfer the ink to the substrate in the tampon printing while a light-shielding mask adhered on the film is transferred by heat in the hot-stump printing.  
         [0110]    Since the light is illuminated on the bottom face of the light-shielding paint or near the interface of the substrate, gas is not significantly emitted from the surface by light irradiation.  
         [0111]    The seventh embodiment of the diffractive optical element according to the present invention will be described hereinafter.  
         [0112]    The diffractive optical element according to the present embodiment differs in that the light-shielding member  1703  of the refractive optical element shown in FIG. 17 is provided by printing and the other constructions are the same as in the third embodiment shown in FIG. 17. A light-shielding member is provided on the back face of the substrate  1001  of the diffractive optical element formed via the steps shown in FIG. 10 through FIG. 13 using the surface alignment mark as a reference point. The printing methods include a screen printing, a tampon printing and hot-stump printing in which an acrylic or epoxy light-shielding ink is printed with a thickness of several to several tens of microns.  
         [0113]    The eighth embodiment of the diffractive optical element according to the present invention will be described hereinafter.  
         [0114]    The diffractive optical element according to the present invention merely differs in that the light-shielding member  1803  in the diffractive optical element shown in FIG. 18 is provided by printing and the other constructions are the same as in the fourth embodiment shown in FIG. 18. The light-shielding member  1803  is provided by printing at the laminated substrate side. The printing methods include a screen printing, a tampon printing and hot-stump printing in which an acrylic or epoxy light-shielding ink is printed at a thickness of several to several tens of microns. The optical axis of the grating member  1801  is aligned with the center of the aperture of the parallel plates  1804  to be laminated at a high precision by taking advantage of an alignment mark provided during or after printing on the light-shielding member  1803 .  
         [0115]    The emission of gas due to irradiation is suppressed by the member  1904  even when light is illuminated on the light-shielding paint.  
         [0116]    [0116]FIG. 20A and FIG. 20B show a front view and cross section, respectively, of the optical barrel having the diffractive optical element in the ninth embodiment according to the present invention.  
         [0117]    The present embodiment differs from the first embodiment shown in FIG. 1A and FIG. 1B in that a reflection type diffractive optical element is used instead of the transmission type diffractive optical element, the other construction being the same.  
         [0118]    In FIG. 20A and FIG. 20B, the reference numeral  2001  is a grating member provided with a diffraction grating, the reference numeral  2002  denotes a barrel and the reference numeral  2003  denotes a light-shielding member while the letters φ and d representing an effective aperture size of the grating member  2101  and an aperture size of the diffractive optical element  1 , respectively.  
         [0119]    An example for manufacturing the reflection type refractive optical element  1  shown in FIG. 20A and FIG. 20B will be described hereinafter.  
         [0120]    A binary type grating member (a diffractive optical element) is manufactured by the manufacturing method in the second embodiment as shown in FIG. 10 though FIG. 13. Since the depth of etching in the reflection type diffractive optical element differs from the depth of etching in the transmission type diffractive optical element, an etching depth optimized for the reflection type diffractive optical element is selected; After depositing chromium on the entire surface by sputtering, a dielectric layer comprising chromium oxide is deposited on the chromium layer by sputtering. Then, a resist is coated on the layer to develop by selectively exposing the grating member, thereby leaving the resist only at the periphery. In the next step, a reflection type diffractive optical element  1  having a light-shielding member  2103  is manufactured by selectively etching the dielectric layer by a reactive ion etching. The grating member on which the metallic layer is applied serves as a reflection type diffractive optical element having a high reflectivity while the periphery on which the dielectric layer is applied serves as the light-shielding member  2103  having a low reflectivity. The refractive optical element  1  is mounted in a barrel  2002  shown in FIG. 20 and the like thereafter. Aluminum, platinum, gold, or silver may be used for the reflective metallic layer. Alumina and SiO 2  are used for the dielectric layer.  
         [0121]    A desired wavefront can be obtained for the incident light to the grating member by reflection and diffraction when a light flux having a large aperture size impinges on the grating member by using the diffractive optical element according to the present invention for the optical system, enabling to serve as a diffractive optical element that does not generate stray light and excess light since the incident light to the periphery is shielded with the light-shielding member.  
         [0122]    An appropriate manufacturing method selected from the first embodiment through the eighth embodiment may be used depending on the required manufacturing cost and accuracy, because the light-shielding member at the periphery of the reflection type diffractive optical element can be manufactured by the same method as used for manufacturing the light-shielding member of the transmission type diffractive optical element.  
         [0123]    While the foregoing embodiments describe the diffractive optical element, the methods can be also applied to the optical elements such as lenses, and prisms, other than the diffractive optical element.  
         [0124]    [0124]FIG. 21 shows the 10th embodiment in which the optical barrel having the diffractive optical element according to the present invention is applied for the projection exposure equipment to be used for the lithographic step among the steps for manufacturing devices including a semiconductor device such as IC and LSI, an imaging device such as CCD and a display device such as a liquid crystal panel.  
         [0125]    In FIG. 21, the reference numeral  2101  denotes an illumination optical system including a light source, the reference numeral  2102  denotes a reticle, the reference numeral  2103  denotes a barrel of a projection optical system  2108 , the reference-numeral  2104  denote a lens, the reference numeral  2105  denotes a diffractive optical element, the reference numeral  2106  denotes a wafer and the reference numeral  2107  denotes a wafer stage. The refractive optical element  2105  can be applied to any of the foregoing embodiments, in which, for example, a light-shielding means may be provided at the periphery of the diffraction face of the diffractive optical element according to the first embodiment. The wafer  2106  is positioned at a desired location with the wafer stage  2107 , and the height of the wafer is adjusted to the focus position with a focus detecting mechanism (not shown). The reticle is aligned, if necessary, against the mark on the lower layer of the wafer that has been exposed using a detection system (not shown). When focusing and alignment have been completed, the shutter (not shown) is opened to illuminate the reticle with the illumination light form the light source  2101 , and the pattern on the reticle  2102  is projected on the wafer  2106  with the projection optical system  2108 . A KrF eximer laser or a ArF eximer laser is used for the light source described above, emitting a UV light with a wavelength of 250 nm or less.  
         [0126]    The device is manufactured through a development step of the wafer  2106  known in the art. The optical barrel having the refractive optical element according to the present invention can be also applied to an image-forming optical instrument or an illumination apparatus as well.  
         [0127]    According to the present invention, the emission of gas by light illumination on the light-shielding area is reduced, thereby avoiding the problem of fog on the lens as well as prolonging the service life of the apparatus.  
         [0128]    Respective embodiments as hitherto described enable reduction of the excess light or scattered light as well as facilitate manufacture of the optical system and maintain good optical performance by appropriately selecting the light-shielding member constituting the optical element, thus attaining an optical element and an optical system using the same.  
         [0129]    Providing a light-shielding member comprising a prescribed material at the optical element allows prevention of excess light from being generated besides excluding the necessity of matching the aperture size of the optical barrel with the effective aperture size of the diffractive optical element as seen in the conventional art, thus relaxing tolerance in manufacturing. When the light-shielding member is enlarged, adhesion of foreign matter to the optical element due to cutting of the periphery is reduced, and allows the entire face of the designed and manufactured diffractive optical element to be effectively utilized as a diffractive optical element without any waste.  
         [0130]    Alternately, providing an alignment mark on the light-shielding member allows effective utilization when the optical element is required to be centered in the optical barrel with a high precision. This mark is very effective since it does not optically generate excess scattered light.  
         [0131]    When the diffractive optical element according to the embodiments as hitherto described are applied to an exposure apparatus, exposure of the wafer is not adversely affected by shielding the light not passing through the diffraction member since the light-shielding mechanism covers the periphery of the diffraction member on the diffraction face of the diffractive optical element. The thickness of the diffractive optical element is less than that of a conventional lens. A high transmittance and exposure efficiency can be attained by manufacturing the diffractive optical element with artificial quartz or fluorite even when the ArF eximer laser or KrF eximer laser is used for the light source.  
         [0132]    Because excess transmission light and scattered light are reduced according to the present invention, the optical element can be readily mounted on the exposure apparatus for manufacturing the semiconductor device, enabling a projection optical system having high optical characteristics to be produced. The optical system according to the present invention has a high transmittance when UV light from the ArF eximer laser or KrF eximer laser is used for the light source, enabling to obtain a projection optical system in which the lens material is less deteriorated.  
         [0133]    Manufacturing and assembling of the optical system using the optical element are made easy, on the other hand, so that the present invention is widely applicable not only for the exposure apparatus for manufacturing the semiconductor device but also for the general purpose optical instruments.  
         [0134]    The eleventh embodiment of the diffractive optical element according to the present invention will be described hereinafter with reference to from FIG. 28 through FIG. 35.  
         [0135]    A light-shielding member is formed in the method for manufacturing the element in the present eleventh embodiment after manufacturing a diffractive optical element having four steps. FIG. 28 to FIG. 35 show the manufacturing method in this embodiment.  
         [0136]    The first resist pattern  1002  is formed by coating the quartz substrate  1001  with a resist. The resist pattern  1003  for the alignment mark to serve as a reference point for the succeeding steps is also simultaneously formed. This manufacturing step is illustrated in FIG. 28. Then, the quartz substrate  1001  is etches to a depth of 1854 Å using the resist- pattern  1002  as a mask. This manufacturing step is illustrated-in FIG. 29. Then, a photoresist is coated on the substrate  1001  to form the second resist pattern  1204 , followed by etching the quartz substrate  1001  to a depth of 977 Å using the resist pattern  1204  as a mask. This manufacturing step is illustrated in FIG. 30. Finally, the resist pattern  1204  are peeled off, thereby completing the grating member of the diffractive optical element shown in FIG. 31.  
         [0137]    The depth of etching is optimized against the wavelength 193 nm of the ArF eximer laser light to be ued.  
         [0138]    A photoresist is then spin-coated to form a photoresist layer  3000 . This manufacturing step is illustrated in FIG. 32.  
         [0139]    Next, exposure and development are carried out so that only the element portion is covered with the photoresist  3001  by aligning the element using the alignment mark  3002 . This manufacturing step is shown in FIG. 33.  
         [0140]    Then, an aluminum film is deposited to a depth of 1000 Å by sputtering. This manufacturing step is shown in FIG. 34.  
         [0141]    While an aluminum film was used for the step described above, the succeeding steps would not be altered by depositing one of any materials of molybdenum, tantalum, tungsten, molybdenum siliside, tungsten siliside, silicon and silicon oxide instead of aluminum, because these materials largely absorb or reflect the light at a wavelength of around 193 nm or, sufficiently serving as a light shielding film.  
         [0142]    In the next manufacturing step, the aluminum film and photoresist film on the element are simultaneously removed by a lift-off method using a peeling solution for the resist. When lift-off is difficult, a scrubber may be used. The element having the light-shielding member is completed after the lift-off step has been applied. This manufacturing step is shown in FIG. 35.  
         [0143]    The element according to the present embodiment is also applicable to the optical system in FIG. 21.