JP3332896B2 - Diffractive optical element and optical system having the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a diffractive optical element having a mark and an optical system having the same. For example, the diffractive optical element of the present invention is used for a camera for forming a subject on a photosensitive member surface. Image forming optical system, image forming optical system for optically scanning the surface of a photosensitive drum to form image information on the surface, electronic circuit of a mask when manufacturing semiconductor elements (devices) such as ICs and LSIs It is suitable for a projection optical system for projecting a pattern on a wafer by a projection optical system (projection lens) and an illumination optical system for illuminating the mask.

[0002]

2. Description of the Related Art In recent years, various types of diffractive optical elements utilizing a light diffraction phenomenon and optical systems having the same have been proposed.
Known diffractive optical elements include, for example, kinoforms, binary optics, Fresnel zone plates, holograms and the like.

[0003] A diffractive optical element is used as an optical element for converting an incident wavefront into a predetermined wavefront. This diffractive optical element has features not found in refraction lenses. For example, it has features such as having a dispersion value opposite to that of a refractive lens and having substantially no thickness.

Conventionally, it is known that a diffraction optical element can have a diffraction efficiency of 100% with respect to a design wavelength by forming a so-called blazed shape or kinoform shape having a sawtooth cross section of a diffraction grating. I have. However, in reality, it is difficult to process a complete blazed shape, so a diffractive optical element called binary optics, which quantizes the blazed shape or kinoform shape and approximates it with a step-like cross-sectional shape, has been used. I have.

[0005] In general, lithography technology can be applied to the production of binary optics, and fine pitch can be realized relatively easily.

FIG. 8 shows an example of such binary optics. Reference numeral 101 denotes a diffractive optical element. FIG. 9 shows a cross-sectional shape of the element 101 at the position of the line 102 in FIG. The diffraction efficiency of the first-order diffracted light can secure 95% or more in the case of 8-level binary optics as shown in FIG.

Here, in order to increase the degree of approximation or to give the diffractive optical element a large power, it is desirable that the pitch of the periodic structure of the diffractive optical element is as small as possible, and a high-performance diffractive optical element is obtained. Therefore, lithography technology cultivated in semiconductor manufacturing is used. Since such a diffractive optical element is processed through a lithography process, the completed element has a thin plate shape.

[0008] A ring-shaped holding member (hereinafter referred to as a thicker than the thin plate-shaped diffractive optical element) is provided on the periphery of the diffractive optical element.
This is called a "cell") to secure the required strength by joining and integrating, and when incorporating a diffractive optical element into the projection optical system barrel, this cell can be held together with the barrel. It is considered. At this time, the positioning of the cell is performed based on the outer diameter of the cell.

As described above, when the above cell is bonded to the diffractive optical element, the center of the cell and the center of the diffractive optical element must coincide with high accuracy. If the centers do not coincide, a so-called eccentric error occurs when the optical system is incorporated into the optical system, and the performance of the entire optical system is reduced due to aberration.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a diffractive optical element which can be easily aligned with another article such as the above-mentioned cell, and an optical system having the same.

[0011]

According to a first aspect of the present invention, there is provided a diffractive optical element having a diffraction surface for diffracting light having a wavelength of λ and a mark, wherein the mark is a light having a wavelength of λ. Of the light passing through the mark and the light passing around the mark generate a phase difference of an integral multiple of λ, and the light having a wavelength λ ′ different from the wavelength λ passes through the mark. And a light beam passing around the mark is provided with a shape that does not cause a phase difference of an integral multiple of λ ′.

According to a second aspect of the present invention, in the first aspect of the present invention, the mark is formed at a center of the diffraction surface or near the center and formed on the diffraction surface. Of the light passing through the mark and the light passing around the mark, a phase difference of an integral multiple of λ is generated, and the light of the wavelength λ ′ passing through the mark And a depth that does not cause a phase difference of an integral multiple of λ ′ between light rays passing around the mark.

According to a third aspect of the present invention, in the first aspect of the present invention, the mark is formed at a center of the diffraction surface or near the center and formed on the diffraction surface. A phase difference of an integral multiple of the λ is generated between a light beam passing through the mark and a light beam passing around the mark of the light of the wavelength λ, and passes through the mark of the light of the wavelength λ ′. And a light beam passing around the mark has a height that does not cause a phase difference of an integral multiple of λ ′.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the diffraction surface and the mark transmit each light beam of the wavelength λ and the wavelength λ '.

The diffractive optical element according to the present invention has a wavelength λ.
A diffractive optical element having a diffraction surface that diffracts light of the wavelength and a mark, wherein the mark is formed between a light reflected by the mark and a light reflected around the mark among the lights of the wavelength λ. A phase difference of an integral multiple of the λ occurs, and a light having a wavelength λ ′ different from the wavelength λ has an integer multiple of the λ ′ between a light ray reflected at the mark and a light ray reflected around the mark. It is characterized by having a shape that does not cause a phase difference.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the mark is formed at a center of the diffraction surface or near the center and formed on the diffraction surface, and the recess is formed at the wavelength λ. Of the light reflected at the mark and the light reflected at the periphery of the mark have a phase difference of an integral multiple of λ, and the light of the wavelength λ ′ reflected at the mark And a depth that does not cause a phase difference of an integral multiple of λ ′ between light rays reflected around the mark.

According to a seventh aspect of the present invention, in the invention of the fifth aspect, the mark is formed at a center of the diffraction surface or near the center and formed on the diffraction surface. A phase difference of an integral multiple of the λ is generated between the light beam reflected by the mark and the light beam reflected around the mark of the light of the wavelength λ, and reflected by the mark of the light of the wavelength λ ′. And a height at which a phase difference of an integral multiple of λ 'does not occur between the light beam reflected and the light beam reflected around the mark.

An eighth aspect of the present invention is characterized in that, in the fifth aspect of the present invention, the diffractive surface and the mark are reflected by the light beams having the wavelengths λ and λ ′.

According to a ninth aspect of the present invention, in the first or fifth aspect, the diffractive surface is binary optics, and the diffractive surface and the mark are formed by lithography.

According to a tenth aspect of the present invention, in the first or the fifth aspect, the substrate on which the diffraction surface and the mark are formed is held by a metal ring.

According to an eleventh aspect of the present invention, in the first or fifth aspect, the mark is located at the center of the diffraction surface, and the mark is located at the center of the outer periphery of the metal ring.

According to a twelfth aspect of the present invention, in accordance with the eleventh aspect of the present invention, the position of the mark and the position of the center position are detected while detecting the position of the mark by using the light having the wavelength λ '. Matching is performed, and the two are matched.

An optical element according to a thirteenth aspect of the present invention is an optical element having an optical surface for reflecting or refracting light having a wavelength of λ and a mark. A phase difference of an integral multiple of λ is generated between the light beam passing therethrough and the light beam passing around the mark, and the light beam passing through the mark and the light beam having a wavelength λ ′ different from the wavelength λ It is characterized in that it has a shape that does not cause a phase difference of an integral multiple of λ ′ with a light beam passing therearound.

According to a fourteenth aspect of the present invention, in the thirteenth aspect, the mark is formed at a center of the optical surface or near the center and formed on the optical surface, and the concave is formed by the wavelength λ. Of the light passing through the mark and the light passing around the mark, a phase difference of an integral multiple of λ is generated, and the light of the wavelength λ ′ passing through the mark And a depth that does not cause a phase difference of an integral multiple of λ ′ between light rays passing around the mark.

According to a fifteenth aspect of the present invention, in the invention of the thirteenth aspect, the mark is formed at a center of the optical surface or near the center and formed on the optical surface. A phase difference of an integral multiple of the λ is generated between a light beam passing through the mark and a light beam passing around the mark of the light of the wavelength λ, and passes through the mark of the light of the wavelength λ ′. And a light beam passing around the mark has a height that does not cause a phase difference of an integral multiple of λ ′.

In a sixteenth aspect of the present invention, in the thirteenth aspect, the optical surface and the mark transmit each light beam of the wavelength λ and the wavelength λ '.

An optical element according to a seventeenth aspect of the present invention is an optical element having an optical surface that reflects or refracts light having a wavelength λ and a mark, wherein the mark is one of the marks of the light having the wavelength λ. A phase difference of an integral multiple of λ is generated between the reflected light beam and the light beam reflected around the mark, and the light reflected at the mark and the light of the wavelength λ ′ different from the wavelength λ It is characterized in that it has a shape in which a phase difference of an integral multiple of λ ′ does not occur between light rays reflected from the surroundings.

According to an eighteenth aspect of the present invention, in the invention according to the seventeenth aspect, the mark comprises a concave portion formed at or near the center of the optical surface and formed on the optical surface, wherein the concave portion has the wavelength λ. Of the light reflected at the mark and the light reflected at the periphery of the mark have a phase difference of an integral multiple of λ, and the light of the wavelength λ ′ reflected at the mark And a depth that does not cause a phase difference of an integral multiple of λ ′ between light rays reflected around the mark.

According to a nineteenth aspect of the present invention, in the invention of the seventeenth aspect, the mark is formed at a center of the optical surface or near the center and formed on the optical surface. A phase difference of an integral multiple of the λ is generated between the light beam reflected by the mark and the light beam reflected around the mark of the light of the wavelength λ, and reflected by the mark of the light of the wavelength λ ′. And a height at which a phase difference of an integral multiple of λ 'does not occur between the light beam reflected and the light beam reflected around the mark.

A twentieth aspect of the present invention is characterized in that, in the seventeenth aspect, the optical surface and the mark are reflected by the light beams of the wavelength λ and the wavelength λ '.

According to a twenty-first aspect, in the thirteenth or seventeenth aspect, the optical surface is a binary optics, and the optical surface and the mark are formed by a lithography method.

The invention of claim 22 is the invention of claim 13 or 17, wherein the substrate on which the optical surface and the mark are formed is held by a metal ring.

According to a twenty-third aspect, in the thirteenth or seventeenth aspect, the mark is located at the center of the optical surface, and the mark is located at the center of the outer periphery of the metal ring.

According to a twenty-fourth aspect of the present invention, in the twenty-third aspect of the present invention, the position of the mark and the position of the center position are detected while detecting the position of the mark by using the light having the wavelength λ '. Matching is performed, and the two are matched.

According to a twenty-fifth aspect of the present invention, an optical system includes the diffractive optical element according to any one of the first to twenty-fourth aspects.

According to a twenty-sixth aspect of the invention, a projection exposure apparatus projects a certain pattern on a substrate by the projection optical system according to the twenty-fifth aspect.

According to a twenty-seventh aspect of the present invention, there is provided a method of manufacturing a device, comprising the steps of exposing a substrate to a device pattern using the projection exposure apparatus of the twenty-sixth aspect, and developing the exposed substrate.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1A and 1B are a front view and a sectional view of a main part of a first embodiment of a diffractive optical element (optical element) according to the present invention. In the drawing, reference numeral 1 denotes a diffractive optical element, which includes a diffraction grating portion 11 provided with a diffraction grating having a binary shape (step shape), a kinoform shape, a Fresnel shape, or the like, and an alignment mark (mark) 2 formed at the center thereof. have.

Although the present embodiment is shown as a transmission type diffractive optical element 1, the present invention can be applied to a reflection type optical element.

The diffractive optical element 1 of the present embodiment is similar to that of FIG.
As shown in (B), a light beam passing therethrough has a desired minute opening a and a desired height (depth) y with respect to its used wavelength λ (design wavelength) and the refractive index n for the wavelength λ of the material of the substrate 4. An alignment mark 2 whose (wavelength λ) has a phase difference of approximately mλ / (n−1) [m is an integer] between a light beam (wavelength λ) passing through the periphery thereof and the diffractive optical element 1 Wavelength λ at the center or near the center of the diffractive optical element
At a desired position in a region through which the light passes.

Since the phase shift (phase difference) due to the alignment mark 2 is an integral multiple of 2π with respect to the peripheral region with respect to the above used wavelength λ, it is substantially used when incorporated in an optical system. Has an effect equivalent to the absence of an alignment mark.

Note that the depth (height) of approximately mλ / (n-1) is within ± 30% of the ideal value.

When positioning the center of the diffractive optical element according to the present embodiment, the wavelength λ '(alignment wavelength) different from the used wavelength λ and substantially mλ are used so that the alignment mark exists substantially. '/ (N'-1) is not satisfied (n' is the refractive index for λ '), and the alignment plane and the wavefront from the vicinity thereof are caused to interfere with the reference plane wave. By detecting, the center of the diffractive optical element 1 with respect to the center of the cell is positioned with high accuracy.

After the cell is bonded to the diffractive optical element according to the present embodiment, the cell may be processed by using the alignment mark 2 as necessary, and the center of the cell may be positioned in the lens barrel.

The arrangement of the alignment mark 2 at the center of the diffractive optical element 1 has conventionally been avoided because it causes scattering and unnecessary diffracted light when used in an optical system. However, by setting the depth with respect to the design wavelength λ as described above, the phase difference between the wavefront passing near the alignment mark and the wavefront passing through the center of the alignment mark is represented by the wave number k = 2π / λ, Where d is the thickness of

[0046]

(Equation 1)

Since this is an integral multiple of 2π, it is equivalent to the absence of a phase difference, and it can be treated as if there is substantially no alignment mark. For example, when this diffractive optical element is incorporated in an optical system using ArF excimer laser light, if synthetic quartz is used as the substrate, the refractive index n = 1.56 and the design wavelength λ = 0.1
The diameter of the fine opening of the alignment mark 2 may be, for example, about 1 μm and the depth may be 3.45 μm.

Such an alignment mark is not limited to a hole having a circular opening, but may be, for example, a columnar projection 23 as shown in FIGS. 2 (A) and 2 (B). In this case, as described above, the thickness of the substrate 24 of the diffractive optical element 1 is d, and the relative refractive index of the glass material forming the substrate 24 is n. At this time, the alignment mark 21 is a column having a diameter a, and the height h is set to approximately mλ / (n−1) [m is an integer].

At this time, the phase difference between the wavefront passing near the alignment mark 21 (peripheral portion) and the wavefront passing the center of the alignment mark is an integral multiple of 2π as in the case shown in FIG. This is equivalent to the absence of a phase difference, and when used at the design wavelength λ, it can be handled as if there is substantially no alignment mark.

The cross-sectional shape of the alignment mark described above may be a shape other than a circle, and may be, for example, a cross mark 31 as shown in FIG. A concave or convex alignment mark 31 provided at or near the center of the diffractive optical element 1
Is approximately mλ / (n-1) [m is an integer]
Holes and protrusions may be used.

FIG. 4 is an explanatory view of a method of aligning the center of an optical element having an alignment mark with the center of a cell according to the present invention. The figure shows a cell 51 in the diffractive optical element 1.
FIG. 3 is a schematic view of a main part of an example in which are bonded.

In the figure, a cell 51 is formed of a ring-shaped holding member thicker than the diffractive optical element 1. Reference numeral 52 denotes a fixing ring for joining the cell 51 and the diffractive optical element 1. Reference numeral 2 denotes an alignment mark provided at the center of the diffractive optical element 1.

In FIG. 4, the center of the cell 51 and the center of the diffractive optical element 1 coincide with each other, and it is not possible to incorporate the optical element together with the cell into the lens barrel of the optical system only after joining in such a state. It becomes possible. A method for joining cells in such a state will be described with reference to FIGS.

FIG. 5 shows the position of the alignment mark (mark) 2 of the diffractive optical element 1, and a part (eccentric part) is cut off while rotating the cell 51 with the center position of the mark 2 as the center of rotation. It is explanatory drawing about the method of performing centering.

In the figure, reference numeral 61 denotes a light source for emitting a plane wave having a wavelength λ 'different from the design wavelength λ; 62, a rotary stage for holding and rotating the cell; 63, a blade for shaving the cell 51; Is a detection system for detecting the alignment mark 2. Further, here, the alignment mark 2 is formed by a hole having a circular opening and a depth of mλ / (n−1) [m is an integer] as shown in FIG.

The centering method will be described below step by step.

First, the cell 51 is joined to the diffractive optical element 1 and fixed with a fixing ring 52. The cell thus attached is fixed to the rotary stage 62. Next, the wavelength λ ′ (λ ′ ≠ mλ ′ / (n′−1)) from the light source 61
A (m is an integer) plane wave is applied to the vicinity of the center of the diffractive optical element 1 as illumination light. At this time, alignment mark 2
Has a phase of 2 in the vicinity with respect to the design wavelength λ of the optical element.
is designed to be an integral multiple of π, and λ '≠ m
Since λ ′ / (n′−1), when a plane wave having an alignment wavelength λ ′ different from the wavelength λ is applied, a light beam passing through the alignment mark 2 and a portion surrounding this portion are passed. A phase shift occurs with the light beam.

As a result, also on the detection surface of the detection system 64, a phase shift occurs between the plane wave transmitted through the alignment mark 2 and the plane wave transmitted around the alignment mark 2. By causing the reference plane wave of the wavelength λ ′ to interfere with the detection surface of the detection optical system, an image of the alignment mark as a high contrast image can be formed and its position can be detected.

Also, the position of the alignment mark 2 can be detected with high accuracy by using a phase contrast microscope as a detection system.

After the alignment mark 2 is detected in this manner, the rotation stage 62 is driven by an XY stage (not shown), so that the center of the detection system 64, which is the rotation center of the rotation stage, and the center of the alignment mark 2 To match. Then, the rotation stage 62 is rotated while maintaining that state.

Then, the blade 63 is slowly brought close to the cell 51 while the stage 62 is rotated, so that an eccentric portion as shown at 65 in FIG. 6 is scraped off. As a result, the center of the cell 51 is aligned with the alignment mark 2.
Process to match the center of For this, cell 5
For 1, it is necessary to join a material larger than a desired size in advance.

The cell 51 after the eccentric portion 65 of FIG. 6 has been scraped off in this way is in the same state as that of FIG. 4 described above. By incorporating this into a lens barrel of a desired optical system, Highly accurate optical axis alignment is possible.

FIG. 7 shows that the optical system having the optical element of the present invention is used in a lithography step of a process for manufacturing devices such as semiconductor devices such as ICs and LSIs, imaging devices such as CCDs, and display devices such as liquid crystal panels. 1 is a schematic view of a main part of an embodiment applied to a projection exposure apparatus to be used.

In the figure, 71 is a light source, 72 is a reticle, 73 is a lens barrel of a projection optical system 78, 74 is a lens, 1 is a diffractive optical element of the present invention, 76 is a wafer, and 77 is a wafer stage.

The diffractive optical element 1 is composed of, for example, the first embodiment, and is provided so as to correct the chromatic aberration of the lens 74. The wafer 76 is moved by the wafer stage 77.
Is positioned at a desired position, and the wafer height is adjusted to the focus position by focus detection means (not shown). Here, a reticle is aligned with a mark of a lower layer which has already been exposed on the wafer by a detection system (not shown) as necessary. When the focus and the alignment are completed, the shutter (not shown) is opened, and the light source 71 is opened.
The reticle is illuminated with illumination light from
Of the circuit pattern on the wafer 7 by the projection optical system 78
6 is exposed on the resist.

The wafer 76 thus exposed becomes a plurality of devices through a known developing process and etching process. The optical system having the optical element according to the present invention can be similarly applied to an optical device for image formation, an illumination device for illumination, and the like. Further, as the optical element of the present invention, there are various refractive elements and various reflective elements other than the diffractive optical element.

[0067]

According to the present invention, an optical element which can be easily aligned with another article such as a cell, and an optical system using the same can be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a principal part of a first embodiment of a diffractive optical element of the present invention.

FIG. 2 is a sectional view of a main part of a second embodiment of the diffractive optical element of the present invention.

FIG. 3 is a sectional view of a principal part of a third embodiment of the diffractive optical element of the present invention.

FIG. 4 is a schematic diagram in which a cell is bonded to the diffractive optical element of the present invention.

FIG. 5 is a schematic view of a main part of a processing method for matching the center of a cell with a diffractive optical element of the present invention.

FIG. 6 is an explanatory diagram of a method of removing an eccentric part of a cell provided in a diffractive optical element.

FIG. 7 is a schematic diagram of a main part of an embodiment of an optical system having a diffractive optical element of the present invention.

FIG. 8 is a schematic diagram of a main part of a conventional diffractive optical element.

FIG. 9 is a sectional view of a main part of a conventional diffractive optical element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Diffractive optical element 2, 21, 31 Alignment mark 51 Cell 61 Illumination optical system 62 Rotation stage 63 Blade 64 Detection optical system 101 Diffractive optical element 11 Diffraction grating 4, 24 Substrate 23 Projection 52 Fixing ring 65 Eccentric part 71 Light source 72 Reticle 73 Projection optical system 74 Lens 76 Wafer 77 Wafer stage 78 Lens barrel

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G02B 5/18 G02B 3/00 G02B 5/08 H01L 21/027

Claims (27)

(57) [Claims] 1. A diffractive optical element having a diffraction surface for diffracting light having a wavelength of λ and a mark, wherein the mark has a wavelength of λ.
Of the light, a phase difference of an integral multiple of the λ occurs between a light ray passing through the mark and a light ray passing around the mark,
The light having a wavelength λ ′ different from the wavelength λ has a shape such that a phase difference of an integral multiple of λ ′ does not occur between a light passing through the mark and a light passing around the mark. A diffractive optical element characterized by the above-mentioned. 2. The mark comprises a concave portion formed at or near the center of the diffractive surface and formed on the diffractive surface, and the concave portion is a light beam of the light having the wavelength λ that passes through the mark. And a light beam passing around the mark has a phase difference of an integral multiple of λ, and a light beam having a wavelength λ ′ between a light beam passing through the mark and a light beam passing around the mark. 2. The diffractive optical element according to claim 1, wherein the optical element has a depth such that a phase difference of an integral multiple of λ 'does not occur. 3. The mark is formed at or near the center of the diffraction surface and includes a convex portion formed on the diffraction surface, and the convex portion passes through the mark of light of the wavelength λ. And a light ray passing around the mark, a phase difference of an integral multiple of λ is generated between the light ray passing through the mark and the light ray passing through the mark. 2. The diffractive optical element according to claim 1, wherein the height is such that a phase difference of an integral multiple of λ 'does not occur between the two. 4. The diffractive optical element according to claim 1, wherein the diffracting surface and the mark transmit each light beam of the wavelength λ and the light beam of the wavelength λ ′. 5. A diffractive optical element having a diffraction surface for diffracting light having a wavelength λ and a mark, wherein the mark has a wavelength of λ.
Of the light, a phase difference of an integral multiple of the λ is generated between a light ray reflected by the mark and a light ray reflected around the mark,
The light having a wavelength λ ′ different from the wavelength λ has a shape such that a phase difference of an integral multiple of λ ′ does not occur between a light beam reflected by the mark and a light beam reflected around the mark. A diffractive optical element characterized by the above-mentioned. 6. The mark comprises a concave portion formed at or near the center of the diffractive surface and formed on the diffractive surface, wherein the concave portion is a light ray of the light having the wavelength λ reflected by the mark. And a light beam reflected around the mark causes a phase difference of an integral multiple of the λ, and a light beam of the wavelength λ ′ is reflected between the light beam reflected at the mark and the light beam reflected around the mark. 6. A diffractive optical element according to claim 5, wherein said optical element has a depth such that a phase difference of an integral multiple of said λ 'does not occur. 7. The mark is formed at or near the center of the diffraction surface and includes a convex portion formed on the diffraction surface, and the convex portion is reflected by the mark of light of the wavelength λ. A phase difference of an integral multiple of λ is generated between the light beam reflected and the light beam reflected around the mark, and the light beam reflected at the mark and the light beam reflected around the mark out of the light of the wavelength λ ′. 6. The diffractive optical element according to claim 5, wherein the height is such that a phase difference of an integral multiple of λ 'does not occur between the two. 8. The diffractive optical element according to claim 5, wherein the diffraction surface and the mark are reflected by the light beams of the wavelengths λ and λ ′. 9. The diffractive optical element according to claim 1, wherein the diffractive surface is binary optics, and the diffractive surface and the mark are formed by a lithography method. 10. The diffractive optical element according to claim 1, wherein the substrate on which the diffraction surface and the mark are formed is held by a metal ring. 11. The diffractive optical element according to claim 1, wherein the mark is located at a center of the diffraction surface, and the mark is located at a center of an outer periphery of the metal ring. 12. The position of the mark is aligned with the center position while detecting the position of the mark by detecting the mark by using the light having the wavelength λ ′. 12. The diffractive optical element according to claim 11, wherein: 13. An optical element having an optical surface that reflects or refracts light having a wavelength λ, and a mark, wherein the mark is a light beam that passes through the mark and a light around the mark out of the light having the wavelength λ. And a light beam passing through the mark and a light beam passing around the mark out of light having a wavelength λ ′ different from the wavelength λ. Wherein the optical element has a shape that does not cause a phase difference of an integral multiple of λ ′. 14. The mark is formed at or near the center of the optical surface and includes a concave portion formed on the optical surface, and the concave portion is a ray of light of the wavelength λ that passes through the mark. And a light beam passing around the mark has a phase difference of an integral multiple of λ, and a light beam having a wavelength λ ′ between a light beam passing through the mark and a light beam passing around the mark. 14. The optical element according to claim 13, wherein the optical element has a depth such that a phase difference of an integral multiple of λ 'does not occur. 15. The mark is formed at or near the center of the optical surface and includes a convex portion formed on the optical surface, and the convex portion passes through the mark of light of the wavelength λ. And a light ray passing around the mark, a phase difference of an integral multiple of λ is generated between the light ray passing through the mark and the light ray passing through the mark. 14. The optical element according to claim 13, wherein the optical element has a height such that a phase difference of an integral multiple of λ 'does not occur between the two. 16. The optical element according to claim 13, wherein said optical surface and said mark transmit each light beam of said wavelength λ and said wavelength λ ′. 17. An optical element having an optical surface that reflects or refracts light having a wavelength λ, and a mark, wherein the mark is a light beam reflected by the mark and a light beam around the mark of the light having the wavelength λ. A phase difference of an integral multiple of the λ is generated between the light reflected at the mark and the light reflected at the mark and the light reflected around the mark among lights having a wavelength λ ′ different from the wavelength λ. An optical element characterized in that the optical element has a shape that does not cause a phase difference of an integral multiple of λ ′. 18. The mark comprises a concave portion formed at or near the center of the optical surface and formed on the optical surface, wherein the concave portion is a ray of light having the wavelength λ which is reflected by the mark. And a light beam reflected around the mark causes a phase difference of an integral multiple of the λ, and a light beam of the wavelength λ ′ is reflected between the light beam reflected at the mark and the light beam reflected around the mark. 18. The optical element according to claim 17, wherein the optical element has a depth such that a phase difference of an integral multiple of λ 'does not occur. 19. The mark includes a convex portion formed at or near the center of the optical surface and formed on the optical surface, and the convex portion is reflected by the mark of the light having the wavelength λ. A phase difference of an integral multiple of λ is generated between the light beam reflected and the light beam reflected around the mark, and the light beam reflected at the mark and the light beam reflected around the mark out of the light of the wavelength λ ′. 18. The optical element according to claim 17, wherein the optical element has a height such that a phase difference of an integral multiple of λ 'does not occur between the optical elements. 20. The diffractive optical element according to claim 17, wherein the optical surface and the mark are reflected by the light beams of the wavelengths λ and λ ′. 21. The optical surface is binary optics,
18. The diffractive optical element according to claim 13, wherein the optical surface and the mark are formed by a lithography method. 22. The diffractive optical element according to claim 13, wherein the substrate on which the optical surface and the mark are formed is held by a metal ring. 23. The diffractive optical element according to claim 13, wherein the mark is located at the center of the optical surface, and the mark is located at the center of the outer periphery of the metal ring. 24. The position of the mark is aligned with the center position while detecting the position of the mark by detecting the mark by using the light of the wavelength λ ′. 24. The diffractive optical element according to claim 23, wherein: 25. An optical system comprising the diffractive optical element according to claim 1. Description: 26. A projection exposure apparatus, wherein a certain pattern is projected on a substrate by the projection optical system according to claim 25. 27. A device manufacturing method, comprising: exposing a substrate with a device pattern using the projection exposure apparatus according to claim 26; and developing the exposed substrate.