JP2000056113A - Diffraction optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deformation due to external force for holding its own weight, of air pressure or the like by joining to another member. SOLUTION: A diffraction optical element 21 obtd. by forming a diffraction grating on a quartz wafer having 200 mm (8 inch) diameter and 0.725 mm thickness is directly joined to a parallel flat plate 20 of a quartz material having 200 mm diameter and 20 mm thickness by optical contact. This joined optical device has optical performance equal to a diffraction optical device obtd. by forming a diffraction grating on a substrate of 20.725 mm thickness and enough stiffness of about 817 times is secured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor exposure apparatus,
The present invention relates to a diffractive optical element used for an optical system such as a camera, a telescope, and a microscope.

[0002]

2. Description of the Related Art Conventionally, a single lens, a cemented lens in which a plurality of lenses are cemented, a prism, and an optical element in which a plurality of optical members are bonded are often used in an optical system mounted on an optical apparatus. Adhesives such as balsams are mainly used for bonding a plurality of lenses, and a diffractive optical element is used in addition to a refractive optical element.

A diffractive optical element is used as an optical element for converting an incident wavefront into a predetermined wavefront. This optical element has a dispersion value opposite to that of a refractive optical element, thereby simplifying the optical system. And so on.

In general, when a diffractive optical element is formed in a binary shape, a semiconductor manufacturing technique can be applied to its manufacture, and a finer pitch can be formed with higher precision than in mechanical grinding or the like. For this reason, research on a binary diffractive optical element in which a blazed shape is approximated by a stepped shape has recently been actively pursued.

A diffractive optical element 1 having a blazed cross-sectional shape B as shown in FIG. 36 can make the diffracted light rate with respect to a design wavelength 100%. However, in reality, it is difficult to process an optical element into a complete blazed cross-sectional shape B.
As shown in FIG. 2, a diffractive optical element 2 called binary optics having a stepped cross-sectional shape S obtained by quantizing a blazed type and approximating the same is used. The diffractive optical element 2 is an approximation of the diffractive optical element 1, but the diffraction efficiency of the first-order diffracted light can be secured to 80% or more by the 4-level binary optics in FIG.

Here, in order to increase the degree of approximation or to provide a large power, it is necessary to make the pitch of the periodic structure as small as possible. Used lithography techniques are used. At present, the semiconductor manufacturing apparatus used in the lithography process is designed on the assumption that a wafer having a thickness of less than 1 mm is handled. Therefore, the diffractive optical element 3 manufactured in the semiconductor lithography process is shown in FIG. It is formed in such a thin disk shape.

FIG. 39 shows the configuration of an exposure apparatus for manufacturing a semiconductor. A mirror 5, an illumination optical system 6, a reticle 7, and a reduced projection are arranged on the optical path of a light source 4 such as KrF, ArF, or F ₂ excimer laser from above. An optical system 8 and a wafer stage 9 are arranged, and a wafer W as a photosensitive substrate is placed on the wafer stage 9.
Is placed.

FIG. 40 is a partially enlarged view of the illumination optical system 6 or the projection optical system 8, and an optical system in which a diffractive optical element 3 and a refractive optical element 11 are combined is formed in a lens barrel 10. Note that a plurality of diffractive optical elements 3 may be used instead of one. Here, since the projection lens system of the semiconductor exposure apparatus requires strict precision, it is general to set the optical axis in the vertical direction in consideration of gravity. Therefore, when the diffractive optical element 3 is used for the projection optical system 8, the diffractive optical element 3 is also arranged horizontally in the optical system.

The light beam L from the light source 4 is guided to the illumination optical system 6 by the mirror 5, and the light beam L passing through the illumination optical system 6 is irradiated on the surface of the reticle 7, and the light beam L having information of the reticle 7 is converted. Is projected onto the wafer W through the projection optical system 8. At this time, the wafer stage 9 is driven to adjust the wafer W to the focus position. Further, the wafer W can be slightly moved up and down so as to cope with expansion and contraction due to thermal distortion or the like, whereby magnification correction and aberration correction of the projection optical system 8 can be performed.

[0010]

However, in the above-mentioned conventional example, the diffractive optical element 2 is formed by a lithography process.
Is designed so as to maintain the highest accuracy within the standard range of the Si wafer. For example, the shape has an outer diameter of 150 mm (6 inches), 200 mm
(8 inches), 300 mm (12 inches), etc., and the thickness range is determined for each dimension.
The thickness range is 0.625 to several mm for manufacturing reasons, and usually becomes a very thin substrate of 1 mm or less. Therefore, the semiconductor manufacturing equipment was modified to be used outside the range of the standard of Si wafer. In such a case, it becomes extremely difficult to maintain the precision of the substrate.

Further, the lithography step includes a resist pattern formation and an etching step. A resist pattern is formed by applying a resist that is an organic substance, irradiating light through a reticle 7 having a surface shape to be processed, exposing, baking, and developing steps to form a resist pattern having a desired surface shape. Form. This resist is applied using a device called a spinner, which spins the substrate at a high speed and applies the resist to a uniform film thickness. Becomes difficult.

In the baking process, since the control is performed in seconds by a hot plate having high temperature controllability, it is very difficult to control the temperature using a material having a low thermal conductivity such as quartz and a thick substrate. In the case of the etching step,
An etching device that uses chemicals with a resist pattern as a mask, or a dry etching device that uses plasma, etc. is used, but is often processed by a high-precision dry etching device. Because of the necessity, as in the case of resist baking, it is very difficult to control the temperature of a material having low thermal conductivity and a thick substrate.

For this reason, it is necessary to use a thin substrate in the lithography process, and the diffractive optical element 3 formed on the thin substrate can be mounted horizontally on the projection optical system 8 by a conventional holding method. When the lens barrel 10 is held in the lens barrel 10, deformation due to the weight of the lens, unevenness in the contact portion due to the processing accuracy of the lens barrel 10, distortion during mounting due to force applied during fixing, and deformation due to atmospheric pressure and temperature fluctuation are likely to occur. The performance at the time of design cannot be exhibited due to the deformation, and the image performance deteriorates.

The outer diameter is 150 mm (6 inches).
Since there are only fixed values such as 00 mm (8 inches) and 300 mm (12 inches), the diffractive optical element 3
When used in an optical system, processing for correcting the outer diameter size after manufacturing the diffractive optical element 3 is required.
When performing this outer diameter processing, shavings adhere to the surface on which the fine pattern is formed because the peripheral glass portion is shaved, and dust entering between the patterns cannot be completely removed by washing. As a result, there is a problem that optical performance is deteriorated.

In order to solve this problem, it is conceivable to obtain a substrate having at least twice the rigidity that can withstand deformation by a method of joining and integrating with another member having a large thickness. However, if an adhesive such as balsam is used to join the lenses at this time, the adhesive may flow around the surface of the diffractive optical element 3 and a gap may be generated due to the bonding, and the flatness may be deteriorated. The internal stress remains due to the applied force, and deformation or breakage due to the residual strain also poses a problem.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a diffractive optical element which is not deformed by its own weight, holding or atmospheric pressure, or is small enough to cause no problem even if deformed, and has stable optical performance.

[0017]

According to a first aspect of the present invention, there is provided a diffractive optical element according to the present invention, in which a diffraction grating deformed by its own weight and / or the pressure and / or pressure of a holding member is joined to another member. By doing so, the deformation of the diffraction grating is prevented or reduced.

In a preferred embodiment of the present invention, the other member is made of a material that does not deform due to the pressure and / or pressure of the holding member.

In a preferred embodiment of the present invention, the diffraction grating is bonded on another member.

Further, in a preferred embodiment of the present invention, the other members are optical elements.

Further, the preferred embodiment of the present invention uses the diffraction grating as a kinoform.

Further, in a preferred embodiment of the present invention, the bonding is performed by an optical contact.

Further, in a preferred embodiment of the present invention, the diffractive optical element of the present invention is applied to an optical system.

Further, in a preferred embodiment of the present invention, the above-described optical system and the stored lens barrel are applied to a manufacturing apparatus.

Further, in a preferred embodiment of the present invention, the above-described manufacturing apparatus is applied to an exposure apparatus.

Further, in a preferred embodiment of the present invention, the above-described exposure apparatus is applied to a device manufacturing method.

Further, a preferred embodiment of the present invention manufactures a semiconductor device using the above-described device manufacturing method.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a cross-sectional view of the first embodiment. A parallel flat plate 20 is formed by using transparent quartz having a diameter of 200 mm and a thickness of 20 mm or a transparent or approximately circular shape as a material, which is not deformed at all or hardly affected by an external force. A diffraction optical element 21 having a linear or annular diffraction grating formed on a transparent quartz wafer having a diameter of 200 mm (8 inches) and a thickness of 0.725 mm is formed on the lower surface of the parallel flat plate 20 by an optical contact. It is directly joined so as to cover it, held by the holding section 22, and incorporated into the optical system. Since the joined optical element exhibits the same optical performance as a diffractive optical element in which a diffraction grating is formed on a substrate having a thickness of 20.725 mm, and the rigidity is proportional to the cube of the thickness and inversely proportional to the weight, It is about 817 times, and sufficient strength can be secured.

FIGS. 2 and 3 are enlarged cross-sectional views of the region A in FIG. 1. In the diffractive optical element 21, a fine concave-convex pattern is formed with high precision by a normal semiconductor process. The diffractive optical element 21 is shown in FIG. 2 and FIG. 3 by four stages of binary optics that are quantized and approximated. However, the quantization number (the number of stages) of the binary optics does not depend on this, and a Fresnel having a blazed shape is used. The same effect can be obtained by using a lens.

FIG. 2 shows an example in which the plane opposite to the surface on which the concavo-convex pattern is formed is joined to the parallel flat plate 20. In this case, the joining area is large, which is advantageous in strength. on the other hand,
As shown in FIG. 3, the bonding may be performed using the surface on which the uneven pattern is formed. In this case, adhesion of dust or the like to the uneven pattern can be prevented, so that cleaning is easy.
Further, a single-layer or multi-layer anti-reflection film may be provided on the bonding surface. If the uppermost layer of the anti-reflection film is made of an oxide such as alumina, particularly SiO ₂ , the bonding with the parallel plate 20 is easy. .

FIG. 4 is a cross-sectional view of the bonding apparatus. A diffractive optical element chuck 24 is fixed on a rotary jig 23. On the upper surface of the chuck 24, two large and small annular projections 25 having different diameters are provided. 26 is projected upward and the projection 2
An exhaust port 27 is provided between 5 and 26. The protrusion 25 is formed slightly lower than the protrusion 26. Further, a cylindrical parallel flat plate holder 29 having three contact portions 28 is circumscribed on the side surface of the jig 23. The center of the parallel flat plate 20 placed on the holder 29 coincides with the center. And chuck 2
Above 4, a mark scope 30 for position measurement is arranged.

A diffractive optical element 21 made of a quartz wafer having a diffraction grating is placed on a chuck 24, and a position measuring mark on the diffractive optical element 21 is observed with a mark scope 30. Center and chuck 24
Adjust so that it matches the center of. When the air is exhausted from the exhaust port 27 and the diffractive optical element 21 is sucked between the protrusions 25 and 26, the diffractive optical element 21 is slightly deformed in a convex shape. The centering of the diffractive optical element 21 may be performed using the grating pattern itself instead of the dedicated mark. After the measurement, the mark scope 30 moves from the joining device to a place where it does not interfere with the joining.

After the alignment of the center of the diffractive optical element 21 and the center of the parallel plate 20 is completed, the parallel plate holder 29
, The parallel plate 20 first contacts the center of the diffractive optical element 21. Next, the deformation of the diffractive optical element 21 is released by evacuating from the exhaust port 27 and gradually returning the negative pressure to the atmospheric pressure, and the diffractive optical element 21 gradually expands the contact surface to the parallel flat plate 20, It is directly joined over the entire surface.

This direct bonding method is called an optical contact, and as shown in FIG. 5, through the water or the like adsorbed on the surface of the optical member, as shown in FIG. This is a bonding method in which optical members are directly bonded by bonding and (b) Van der Waals force, and optical members such as glass and quartz can be bonded to each other without using an adhesive or the like. At this time, in order to obtain a sufficient adhesive strength, the surface roughness of the joint between the parallel plate 20 and the diffractive optical element 21 is set to 5 nm or less in a root-mean-square manner, and the water content is set to 10 ^13.
It is preferable to control it to be at least molecule / cm ² .

Normally, a gap h at a fine level is formed on the surface of the joint as shown in FIG. 6, but when r is the radius, γ is the surface energy, E is the elastic modulus, and t is the thickness. It is known that direct bonding is possible as long as the following formula is satisfied. h / r ² <(γ / E / t ³ ) ^1/2 (1)

Equation (1) is for the case where one gap h exists, but there are countless gaps in the entire substrate having a diameter of 200 mm. From equation (1), it can be concluded that the gap h and the surface energy γ
It is understood that the surface roughness measured by AFM or the like and the water content measured by APIMS or the like serve as references. Therefore, in order to ensure the surface roughness of the diffractive optical element 21, before processing the diffractive optical element 21 in a semiconductor process, the surface roughness of the substrate is ensured by polishing or the like, and further, during processing and after the processing. Roughness must be carefully considered.

Regarding the surface energy γ, a normal quartz substrate can secure a water content of 10 ¹³ molecules / cm ² , so that a sufficient surface energy γ can be obtained, but the substrate is dirty. And the surface energy γ becomes insufficient. In the case of a hydrophilic material such as quartz, it is possible to recover the water content by cleaning with a chemical solution or ultraviolet / ozone. However, in the case of a hydrophobic material, water is further sprayed after cleaning or treated with a hydrophilic chemical solution. By doing so to ensure the water content.

If such a substrate is prepared and joined by the joining apparatus shown in FIG. 4, the substrates are joined by hydrogen bonding and van der Waals force. At this time, if there is too much water remaining between the substrates, the bonding strength will be weakened, so the water amount before bonding is adjusted, and after bonding, drying is performed at room temperature or heating is performed to reduce the water amount. It is preferred that The desorption of the adsorbed water occurs at about 200 to 400 ° C., ideally in a state as shown in FIG.
Actually, since there is a gap between the substrates, water of about several molecules remains as shown in FIG. At this time, the bonding strength is 1
Since it is about 0 kg / cm ² and the strength is insufficient depending on the method of use, it is preferable to reinforce the outer periphery of the portion outside the effective diameter with an adhesive or the like. Also, 400
The bonding strength may be increased by heating to １０００1000 ° C. to cause a dehydration-condensation reaction and replacing hydrogen bonds with covalent bonds.

Regarding the optical characteristics at the joint surface, it is preferable that the loss of the reflectance and the transmittance at the wavelength used is 0.1% or less, and dust and the like remain, and a lot of air or water exists. In such a case, the optical characteristics may not be maintained in some cases. Therefore, the substrate management before the bonding is important not only from the viewpoint of the bonding strength but also from the viewpoint of the optical characteristics.

Although the same material quartz is used for both the diffractive optical element 21 and the parallel plate 20, an oxide such as alumina, calcium fluoride, lithium fluoride, barium fluoride, magnesium fluoride is used for the parallel plate 20 to be joined. By using a fluoride such as strontium fluoride, an optical member for a short wavelength can be formed. In addition, as an optical member for long wavelength,
A glass material, a plastic material, or the like is preferably used for the parallel flat plate 20 to be joined, and a ceramic material such as SiN or SiC or a metal can be used for a diffractive optical element of a reflection optical system. For example, OH
Bonding is easy because the surface state for supplying hydrogen, such as the distribution interval of groups, is the same.

In this manner, an optical element having a fine lattice pitch having a rigidity of twice or more the strength can be manufactured with high accuracy, and is not affected by external force. It is possible to exhibit in optical performance. Further, by using a direct bonding method by hydrogen bonding or Van der Waals force, it can be stably used in an optical system using light of a short wavelength.

As a modification of the first embodiment, the diameter is 300
parallel plate 20 made of quartz having a thickness of 30 mm and a thickness of 30 mm
Has a diameter of 300mm (8 inches) and a thickness of 0.775mm
Optical element 21 having diffraction grating formed on quartz wafer
Are directly joined in the same manner as in the first embodiment,
2 and incorporated into the optical system. This optical element has a thickness of 3
The optical performance is equivalent to that of the diffractive optical element having 0.775 mm, and the rigidity is about 1577 times.

Further, as shown in FIG. 9, the diffractive optical element 21 may be directly joined to the parallel flat plate 20 with the diffraction grating surface facing upward, and as shown in FIG.
The surfaces on the side opposite to the surface on which the first diffraction grating is formed may be joined. Furthermore, as shown in FIGS. 11 and 12, the peripheral portion of the parallel plate 20 may be left, and the diffractive optical element 21 may be directly joined near the central portion, and the peripheral portion may be held by the holding portion 22.

As another joining method, there is a method of fixing the circumferential portion with an adhesive as shown in FIG. That is, the parallel flat plate 20 and the circumferential side surface of the diffractive optical element 21 are bonded by the adhesive 31. FIG. 14 is an enlarged view of the bonding portion of FIG. FIG. 15 shows the diffraction optical element 21.
The surface opposite to the surface on which the diffraction grating is formed is bonded to the parallel flat plate 20.

Thus, the back surface of the diffractive optical element 21 which is secured to the parallel flat plate 20 having a sufficient thickness to secure the strength can be easily polished. That is, as shown in FIG. 16, when the workpiece is held by the work chuck 32 and polished by the lapping machine 33, a high level of technique is required to keep the processing pressure constant in the state of a thin wafer. By bonding the element 21 to secure the rigidity, it becomes possible to perform processing of the back surface and the like by the conventional technique. In addition, the optical element in which the lattice forming surfaces are joined to each other can protect the uneven pattern from adhesion of dust and the like,
Furthermore, since both surfaces become flat after bonding, cleaning becomes easy, and generation of unnecessary stress due to a temperature change can be suppressed.

FIG. 17 shows a sectional view of the second embodiment. A parallel plate 32 made of quartz having a diameter of 200 mm and a thickness of 0.725 mm, and a quartz plate having a diameter of 200 mm (8 inches) and a thickness of 0.725 mm are provided. Diffractive optical element 33 made of wafer
Are directly joined in the same manner as in the first embodiment, and are held in the holding section 22 and incorporated into the optical system. Thereby, it is possible to exhibit optical performance equivalent to that of a diffractive optical element having a thickness of 1.45 mm and to secure about four times the rigidity.

FIG. 18 shows a sectional view of the third embodiment, in which a parallel flat plate 34 made of quartz having a diameter of 180 mm and a thickness of 5 to 20 mm, a diameter of 150 mm (6 inches) and a thickness of 0.1 mm are used.
The diffraction optical element 35 made of a 625 mm quartz wafer is held in the holding section 22 and incorporated into the optical system. As described above, when the parallel flat plates 34 are arranged in the direction of gravity below the diffractive optical element 35, they may or may not be joined. Further, the outer diameter is preferably about 180 mm, but the range through which light is actually transmitted is within 150 mm in diameter.Therefore, processing may be performed by a semiconductor process using a quartz wafer having a standard size of 150 mm. Since it is not necessary to perform the outer diameter processing after the formation of the fine pattern, it is possible to avoid the attachment of dust and the like due to the cutting processing or the like.

FIG. 19 is a sectional view of the fourth embodiment, in which a parallel flat plate 36 made of fluorite (CaF ₂ ) having a diameter of 170 mm and a thickness of 30 mm, a diameter of 150 mm (6 inches),
The diffractive optical element 37 made of a quartz wafer having a thickness of 0.625 mm is directly joined to the holder 2 in the same manner as in the first embodiment.
2 and incorporated into the optical system. Similarly to the third embodiment, when the parallel flat plate 36 is arranged in the direction of gravity below the diffractive optical element 37, it may or may not be joined, and conversely, the diffractive optical element 36 moves downward in the direction of gravity. Element 37
May be directly bonded. Further, the bonding surface may be a surface on which a concavo-convex pattern is formed or a surface on which it is not formed. In the case of performing direct bonding, bonding is performed by hydrogen bonding and Van der Waals force shown in FIG. Fluorite has a higher polarity than quartz, and may contain ionic bonds. In addition, since the transmittance on the short wavelength side is high, a thicker member can be used.

Also, as shown in FIGS. 20 to 22, one or more antireflection films 38 may be provided on the bonding surface. FIG.
Forms an anti-reflection film 38 on a fluorite parallel flat plate 36. This anti-reflection film 38 supplies hydrogen to a diffractive optical element 37 made of quartz if an oxide such as alumina or SiO ₂ is used as the uppermost layer. Since the state of the surface is closer than the distribution interval of the OH groups, bonding is easy.

FIG. 21 shows an anti-reflection film 38 formed on a diffractive optical element 37 made of quartz, and this anti-reflection film 38 has a fluoride, for example, calcium fluoride, lithium fluoride, barium fluoride on its uppermost layer. If magnesium, strontium fluoride or the like is used, a parallel plate 36 made of fluorite is used.
Since the state of the surface supplying hydrogen and hydrogen is closer to the distribution interval of OH groups, for example, bonding is easy.

FIG. 22 shows that an anti-reflection film 38 is formed on both a diffractive optical element 37 made of quartz and a parallel flat plate 36 made of fluorite. If the materials described above, that is, oxides or fluorides are used, the state of the surface for supplying hydrogen, such as the distribution interval of OH groups, becomes the same, so that bonding is easy.

FIG. 23 is a sectional view of the fifth embodiment, in which a parallel flat plate 39 made of fluorite having a diameter of 220 mm and a thickness of 20 mm, a diameter of 200 mm (8 inches) and a thickness of 0.72.
The diffractive optical element 40 made of a 5 mm fluorite wafer is
As in the case of the first embodiment, the substrates are directly joined, held by the holding unit 22 and incorporated into the optical system. Also in this case, the diffractive optical element 40 may be provided in the downward direction of gravity, and when performing direct bonding, bonding is performed by hydrogen bonding and Van der Waals force using the bonding apparatus of FIG. Since fluorite has a higher polarity than quartz, the ratio of ionic bonds increases, and the transmittance on the short wavelength side is high, so that thicker members and shorter wavelengths can be used. F ₂ laser light (157n
In the case of light having a short wavelength of 170 nm or less such as m), use of a fluoride such as fluorite or magnesium fluoride is more advantageous in terms of transmittance and the like.

FIGS. 24 to 27 show sectional views of the sixth embodiment, in which the diameter is 200 mm (8 inches) and the thickness is 0.725 m.
A diffractive optical element 41 having a diffraction grating formed on a quartz or fluorite wafer of m is used, and a plano-convex lens, a plano-concave lens, a plane-aspheric lens, a prism, a mirror, or the like is used as a joining member.

FIG. 24 shows a plano-convex lens 42 made of fluorite having a diameter of 220 mm as a material, FIG. 25 shows a plano-concave lens 43 made of quartz having a diameter of 200 mm, and FIG. And a flat aspherical lens 44. In FIG. 27, a diffractive optical element 45 composed of a square substrate of 150 × 200 mm made of quartz having a thickness of 0.725 mm and a cylindrical lens 46 of 150 × 200 mm made of quartz are joined.

In FIGS. 24 to 27, the third
The direct joining may be performed or the joining may not be performed as in the embodiment. In this way, by joining with another member having optical characteristics, sufficient rigidity can be ensured, and the increase in the optical path length in the glass material of the entire optical system can be suppressed or reduced.

FIG. 28 is a sectional view of the seventh embodiment, which is used for a reflection type optical system. 220mm in diameter,
A parallel plate 47 made of SiC having a thickness of 30 mm and a diameter of 2
The diffractive optical element 48 made of a quartz wafer having a thickness of 00 mm (8 inches) and a thickness of 0.725 mm is directly bonded as in the first embodiment, and is held by the holding member 49 of the reflection optical system. Since optical properties are not required for the parallel plate 48, SiC having a relatively small coefficient of thermal expansion, high rigidity, and good thermal conductivity is used, but other ceramic materials or metals may be used. Even in the reflection type diffractive optical element 48, it is possible to accurately produce an optical element having a rigidity of twice or more and a fine grating pitch, and to be used in an optical system without being affected by external force. Can be.

FIGS. 29 to 32 show sectional views of the eighth embodiment, in which the diameter is 200 mm (8 inches) and the thickness is 0.725 m.
A diffractive optical element 51 having a diffraction grating formed on a quartz or fluorite wafer of m is used. In the case of FIG.
parallel plates 52 made of quartz having a thickness of 10 mm and a thickness of 10 mm
Are bonded to both surfaces of the diffractive optical element 51. by this,
It prevents dust and the like from adhering to the uneven pattern, and facilitates cleaning. In the case of FIG. 30, the diameter is 200 mm and the thickness is 10
A flat plate 52 made of quartz having a diameter of 225 mm and a plano-convex lens 53 made of fluorite having a diameter of 225 mm
1. Join both sides.

In the case of FIG. 31, two plano-convex lenses 53 made of fluorite having a diameter of 200 mm are connected to the diffractive optical element 5.
1. Join both sides. In the case of FIG. 32, a plano-convex lens 53 made of quartz or fluorite and a plano-concave lens 54 made of quartz having a diameter of 200 mm are bonded to both surfaces of the diffractive optical element 51. It should be noted that in FIGS.
It is not necessary to join them directly as in the embodiment of FIG.

As described above, by joining members to both surfaces of the diffractive optical element 51, it is possible to prevent dust and the like from adhering to the concavo-convex pattern and to facilitate cleaning. In addition, since the members to be joined also have optical characteristics, sufficient rigidity can be ensured, and an increase in the optical path length in the glass material of the entire optical system can be suppressed or reduced.

FIG. 33 is a partially enlarged view of an optical system of a semiconductor exposure apparatus. A reinforced diffractive optical element 56 is used in an optical system held by a lens barrel 55. The diffractive optical element 56 of this embodiment is the diffractive optical element 3 described in the conventional example of FIG.
The rigidity is more than twice that of
Non-uniformity of the contact portion due to the processing accuracy of the lens barrel 55, distortion at the time of mounting due to force applied at the time of fixing, and deformation due to atmospheric pressure or temperature fluctuation are reduced or eliminated. Therefore, the aberration can be reduced by avoiding the surface deformation, so that the optical performance is improved and the performance at the time of design can be sufficiently exhibited.

In addition, since the number of lenses can be reduced as compared with an optical system using only a refractive optical element, light absorption by the glass material is reduced, and deformation of the lens and change in refractive index due to heat of absorption are suppressed. It is possible to do. Further, since the correction of the chromatic aberration is facilitated, the wavelength band of the laser light can be widened and the power of the laser light can be used effectively. Furthermore, even when the environment in which the semiconductor exposure apparatus is installed changes, the occurrence of a shift in the focal position can be minimized, so that high-accuracy pattern transfer can be favorably performed.

FIG. 34 is a flow chart for manufacturing a semiconductor chip such as an IC or LSI or a semiconductor device such as a liquid crystal panel or a CCD. In the circuit design process of Step 1, a circuit of a semiconductor device is designed. In the mask manufacturing process of step 2, an X-ray mask on which the designed circuit pattern is formed is manufactured. In the wafer manufacturing process of Step 3, a wafer is manufactured using a material such as silicon. Step 4
The wafer process is referred to as a pre-process, in which an actual circuit is formed on a wafer by a prepared semiconductor exposure apparatus.

Next, the assembling process of step 5 is called a post-process, and is a process of forming a semiconductor chip using the wafer manufactured in step 4, such as a dicing and bonding assembly process, a chip encapsulation packaging process, and the like. Contains. In the inspection step of Step 6, inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in Step 5 are performed. Through the above steps, the semiconductor device is completed, and is sent to the shipping step of step 7.

FIG. 35 is a flowchart of the wafer process. First, in the oxidation step of step 11, the surface of the wafer is oxidized. In the CVD process of Step 12,
An insulating film is formed on the wafer surface. In the electrode forming step of Step 13, electrodes are formed on the wafer by vapor deposition. In the ion implantation step of step 14, ions are implanted into the wafer. In a resist processing step of Step 15, a resist is applied to the wafer.

In the exposure step of step 16, the circuit pattern of the mask is printed and exposed on the wafer by the prepared semiconductor exposure apparatus. The wafer is loaded, the wafer is opposed to the mask, the misalignment is detected by the alignment unit, and the wafer stage is driven to align the two. When the positions match, exposure is performed, and after the exposure is completed, the wafer is step-moved to the next shot, and the operations following alignment are repeated.

In the developing step of Step 17, the exposed wafer is developed. In the etching step of Step 18,
A part other than the developed resist is scraped off. By repeating these steps, multiple circuit patterns are formed on the wafer.

The diffractive optical element described in the above embodiment is
Improves rigidity by integrally joining with other members, enabling precise machining regardless of the fine pitch structure, non-uniformity and fixation of contact parts due to self-weight deformation and machining accuracy of the lens barrel Prevents distortion during mounting due to occasional force, etc., deformation due to atmospheric pressure and temperature fluctuations, can be incorporated into the optical system without generating surface deformation, and can be used stably in the optical system for short wavelength light Become.

Further, since the number of optical members can be reduced, light absorption by the glass material is reduced, and deformation and change in refractive index due to heat absorbed can be suppressed.

Further, in order to facilitate correction of chromatic aberration,
The power of the laser light can be effectively used by widening the wavelength band of the laser light, and even when the environment in which the semiconductor exposure apparatus is installed changes, the occurrence of focal position shift is minimized to minimize aberrations. Therefore, the performance at the time of design is sufficiently exhibited, and the image performance is improved. This makes it possible to cope with mass production of semiconductor devices having a high degree of integration, which has conventionally been difficult to manufacture.

[0070]

As described above, the diffractive optical element according to the present invention has a small deformation and can stabilize the optical performance by being joined to another member.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment.

FIG. 2 is a partially enlarged sectional view of a joint.

FIG. 3 is a partially enlarged sectional view of a joint.

FIG. 4 is a cross-sectional view of the joining device.

FIG. 5 is an explanatory diagram of a reaction process.

FIG. 6 is an explanatory diagram of a fine structure.

FIG. 7 is an explanatory diagram of a reaction process.

FIG. 8 is an explanatory diagram of a reaction process.

FIG. 9 is a sectional view in a joining direction.

FIG. 10 is a sectional view in a joining direction.

FIG. 11 is a sectional view of a joining position.

FIG. 12 is a sectional view of a joining position.

FIG. 13 is a cross-sectional view of bonding with an adhesive.

FIG. 14 is a partially enlarged sectional view.

FIG. 15 is a partially enlarged sectional view.

FIG. 16 is a side view of the back surface processing.

FIG. 17 is a sectional view of the second embodiment.

FIG. 18 is a sectional view of the third embodiment.

FIG. 19 is a sectional view of the fourth embodiment.

FIG. 20 is a sectional view of a modification.

FIG. 21 is a sectional view of a modification.

FIG. 22 is a sectional view of a modification.

FIG. 23 is a sectional view of the fifth embodiment.

FIG. 24 is a sectional view of a sixth embodiment.

FIG. 25 is a sectional view of a modification.

FIG. 26 is a sectional view of a modification.

FIG. 27 is a sectional view of a modification.

FIG. 28 is a sectional view of the seventh embodiment.

FIG. 29 is a sectional view of the eighth embodiment.

FIG. 30 is a sectional view of a modification.

FIG. 31 is a sectional view of a modification.

FIG. 32 is a sectional view of a modification.

FIG. 33 is a configuration diagram of an optical system of the exposure apparatus.

FIG. 34 is a flowchart of the manufacture of a semiconductor device.

FIG. 35 is a flowchart of a wafer process.

FIG. 36 is a cross-sectional view of a conventional Fresnel lens.

FIG. 37 is a sectional view of binary optics.

FIG. 38 is a perspective view of a diffractive optical element.

FIG. 39 is a configuration diagram of a semiconductor exposure apparatus.

FIG. 40 is a configuration diagram of an optical system.

[Explanation of symbols]

20, 32, 34, 36, 39, 47, 52 Parallel plates 21, 33, 35, 37, 40, 41, 45, 48, 5,
1, 56 Diffractive optical element 22 Holder 23 Rotating jig 24 Diffractive optical element chuck 25, 26 Projection 27 Exhaust port 29 Parallel flat plate holder 30 Mark scope 38 Antireflection film 42, 53, Plano-convex lens 43, 54 Plano-concave lens 44 Flat Spherical lens 46 Cylindrical lens 49 Holding member

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[Procedure amendment]

[Submission date] October 29, 1998 (1998.10.
29)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 21

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0022

[Correction method] Change

[Correction contents]

Further, the preferred embodiment of the present invention
Tikal Contact GToDo more.

[Procedure amendment 3]

[Document name to be amended] Drawing

[Correction target item name] FIG.

[Correction method] Change

[Correction contents]

FIG. 16

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) G03F 7/20 521 G03F 7/20 521 H01L 21/027 H01L 21/30 515D (72) Inventor Keiko Chiba Tokyo 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term (reference) within Canon Inc.

Claims (44)

[Claims] 1. A diffractive optic, wherein a diffraction grating deformable by its own weight and / or pressure and / or pressure of a holding member is joined to another member to prevent or reduce the deformation of the diffraction grating. element. 2. The diffractive optical element according to claim 1, wherein the other member is made of a material that is not deformed by its own weight and / or the pressure and / or pressure of the holding member. 3. The diffractive optical element according to claim 1, wherein the other member is a member that is deformed by its own weight and / or pressure and / or pressure of a holding member. 4. The diffractive optical element according to claim 1, wherein the diffraction grating deformed by its own weight is joined to the other member. 5. The diffraction grating and the other member both have a circular shape or a shape close to a circle, and the diameter of the other member is larger than the diameter of the diffraction grating, and the other member is installed in a lens barrel. The diffractive optical element according to claim 1, wherein the diffraction grating is supported only at a peripheral portion of the member. 6. The diffractive optical element according to claim 1, wherein the other member is joined so as to cover a grating forming surface of the diffraction grating. 7. The diffraction grating according to claim 1, wherein the diffraction grating is a transparent plate having a linear or annular grating, and the other member is a parallel plane transparent plate. Diffractive optical element. 8. The diffraction grating is a transparent plate having a linear or ring-shaped grating formed thereon, and the other member is a plane-aspheric lens or a plano-convex lens or a plano-concave lens whose one surface is flat and the other surface is aspheric. 7. A prism or a mirror, wherein a grating forming surface or a grating non-forming surface of the diffraction grating is joined to the plane-aspheric lens, plano-convex lens, plano-concave lens, or prism or mirror plane. A diffractive optical element according to claim 1. 9. The diffractive optical element according to claim 1, wherein the diffraction grating has a grating formed of a linear or annular reflecting surface. 10. The diffraction grating has a thickness of 0.1 to 10 m.
m, a linear or annular grid is formed on a substrate having a diameter or length of 150 mm or more.
The diffractive optical element according to claim 9. 11. The diffractive optical element according to claim 10, wherein the other member is a member thicker than the diffraction grating. 12. The diffractive optical element according to claim 1, wherein both the diffraction grating and the other member are made of quartz. 13. The diffractive optical element according to claim 1, wherein both the diffraction grating and the other member are made of fluorite or magnesium fluoride. 14. The diffractive optical element according to claim 1, wherein the diffraction grating is made of quartz, and the other member is made of fluorite. 15. The diffractive optical element according to claim 1, wherein the diffraction grating is a kinoform. 16. The diffractive optical element according to claim 1, wherein a grating of the diffraction grating is a binary type in which a kinoform is approximated by three or more steps. 17. The diffractive optical element according to claim 1, wherein the diffraction grating has a finite focal length. 18. The diffractive optical element according to claim 17, wherein the diffraction grating has a function as a lens. 19. The diffractive optical element according to claim 18, wherein the diffraction grating has a function as an aspheric lens. 20. The diffractive optical element according to claim 17, wherein the diffraction grating has a function as a mirror. 21. The diffractive optical element according to claim 18, wherein the diffraction grating has a function as an aspherical mirror. 22. The diffractive optical element according to claim 1, wherein the diffraction grating and the other member are joined by an optical contact. 23. The diffractive optical element according to claim 1, wherein the diffraction grating and the other member are joined by an adhesive. 24. The diffraction grating and the other member are joined by an optical contact and an adhesive.
The diffractive optical element according to any one of claims 14 to 14. 25. The diffractive optical element according to claim 1, wherein the other member is a diffraction grating. 26. The method according to claim 1, wherein two of the other members are prepared, and the two other members are joined by sandwiching the diffraction grating from both sides. Diffractive optical element. 27. An apparatus according to claim 1, wherein an anti-reflection means is formed at a junction between said diffraction grating and said another member.
A diffractive optical element according to claim 1. 28. The diffractive optical element according to claim 1, wherein the grating forming surface of the diffraction grating is arranged in an inert gas such as nitrogen or helium. 29. The diffractive optical element according to claim 29, wherein the inert gas is caused to flow along the grating forming surface. 30. The diffraction grating according to claim 1, wherein the diffraction grating has a smooth grating-free surface on the side opposite to the grating-formed surface.
A diffractive optical element according to claim 1. 31. An optical system having the diffractive optical element according to any one of claims 1 to 30. 32. A manufacturing apparatus comprising a lens barrel storing the optical system according to claim 31. 33. The manufacturing apparatus according to claim 32, wherein the optical system is supported only at a peripheral portion of the other member. 34. The manufacturing apparatus according to claim 33, wherein the other member is fixed to the lens barrel via an elastic member. 35. The manufacturing apparatus according to claim 33, wherein the inside of the lens barrel is filled with an inert gas of nitrogen or helium. 36. The optical system has a plurality of lenses,
33. The manufacturing apparatus according to claim 32, wherein chromatic aberration caused by the plurality of lenses is corrected by chromatic aberration of the one or more diffractive optical elements. 37. The manufacturing apparatus according to claim 32, wherein an optical axis of said optical system is parallel to a direction of gravity. 38. An exposure apparatus for exposing a substrate to be exposed by a device pattern using the manufacturing apparatus according to any one of claims 32 to 37. 39. The exposure apparatus according to claim 38, wherein the light used for the exposure is laser light from an excimer laser light source. 40. The exposure apparatus according to claim 39, wherein the excimer laser light source is a KrF excimer laser light source. 41. The exposure apparatus according to claim 39, wherein the excimer laser light source is an ArF excimer laser light source. 42. The exposure apparatus according to claim 38, wherein said optical system reduces and projects a circuit pattern of a reticle onto said substrate to be exposed. 43. A device manufacturing method for transferring a device pattern including a stepped shape onto a wafer by using the exposure apparatus according to any one of claims 38 to 42. 44. A semiconductor device manufactured by the device manufacturing method according to claim 43.