WO2002021187A1

WO2002021187A1 - Object lens system, observing device equipped with the object lens system, and exposure system equipped with the observing device

Info

Publication number: WO2002021187A1
Application number: PCT/JP2001/007715
Authority: WO
Inventors: Tadashi Nagayama; Ayako Nakamura
Original assignee: Nikon Corporation
Priority date: 2000-09-07
Filing date: 2001-09-05
Publication date: 2002-03-14
Also published as: JPWO2002021187A1

Abstract

A method of producing an object lens system capable of satisfactorily minimizing remaining wave front aberration higher-order components. The method of producing an object lens system (7) comprises the step of producing respective optical members constituting an object lens system by minimizing, in order to minimize wave front aberration higher-order components remaining in an object lens system, the wave front aberration, due to a refractive index distribution, of respective optical members, and wave front aberration, with respect to a reference plane, of respective planes of respective optical members, and the step of optically adjusting an object lens system for the purpose of correcting aberration remaining in an assembled objective lens system.

Description

Description Objective lens system, observation apparatus equipped with the objective lens system,

And exposure apparatus having the observation device

The present invention relates to an objective lens system, an observation device provided with the objective lens system, and an exposure device provided with the observation device. The present invention particularly relates to an objective lens system suitable for an observation apparatus mounted on an exposure apparatus used in one step of lithography for manufacturing a micro device such as a semiconductor device, an imaging device, a liquid crystal display device, and a thin film magnetic head. It is. Background art

Generally, when manufacturing a device such as a semiconductor element, a circuit pattern of a plurality of layers is formed on a wafer (or a substrate such as a glass plate) coated with a photosensitive material. For this reason, an exposure apparatus for exposing a circuit pattern on a wafer includes an alignment apparatus for aligning a pattern of a mask with each exposure area of a wafer on which a circuit pattern is already formed. Provided.

Conventionally, this type of alignment apparatus has been disclosed in Japanese Patent Application Laid-Open No. 4-65603 (and corresponding US Pat. Nos. 5,493,403, 5,657,129, and 5,995,234). As disclosed in Japanese Unexamined Patent Publication (Kokai) No. 4-273246 (and corresponding US Pat. No. 6,141,107), an alignment apparatus of an off-axis type and an imaging type is known. Have been. The detection system of this imaging type alignment device is also called an FIA (Field Image Alignment) system. In the FIA system, the alignment mark (wafer mark) on the wafer is illuminated with light with a wide wavelength bandwidth emitted from a light source such as an octogen lamp. Then, an enlarged image of the wafer mark is formed on the image sensor via the imaging optical system, and the position of the wafer mark is detected by performing image processing on the obtained image signal.

As mentioned above, the FIA system uses broadband illumination, so the photo on the wafer There is an advantage that the influence of thin film interference on the resist layer is reduced. However, in conventional FIA imaging optics, aberrations remain to a small extent through manufacturing processes such as processing, assembly, and adjustment. If the aberration remains in the imaging optical system, the contrast of the wafer mark image on the imaging surface is reduced, or the wafer mark image is distorted, and a mark position detection error occurs. In recent years, with the miniaturization of circuit pattern line width, high-precision alignment has been required.

Of the aberrations remaining in the optical system, especially the aberration that is asymmetrical to the optical axis, such as coma, has a large effect on the detection of the wafer mark image. If an asymmetric lateral aberration occurs in the optical axis at the pupil such as coma aberration, the wafer mark image formed on the imaging surface is measured with a position shift compared to the case of ideal imaging. In addition, when the shape of the wafer mark (pitch, duty ratio, step, etc.) changes, or when the wafer mark is defocused, the degree of the influence of coma aberration on the wafer mark image changes variously. The amount of displacement of the measurement position will also change variously. In addition, if symmetric aberrations such as spherical aberration occur in the optical axis, the back focus position changes every time the shape of the wafer mark changes.

In general, since the shape of a wafer mark is different in each manufacturing process of a semiconductor device, when a wafer is aligned (aligned) with an optical system in which a frame difference remains, a so-called process offset occurs. Therefore, in order to correct the residual coma as described above, the present applicant has disclosed in Japanese Patent Application Laid-Open No. Hei 8-195336 (and corresponding US Pat. No. 5,680,200). And U.S. Pat. Nos. 5,754,299) propose a method of correcting coma in an optical system following an objective lens. However, in the method disclosed in Japanese Patent Application Laid-Open No. 8-1953336, only low-order coma can be corrected, and it is difficult to correct high-order coma. . As described above, in general, the low-order component of the wavefront aberration can be corrected by optical adjustment, but the high-order component of the wavefront aberration is difficult to correct by optical adjustment. — In Japanese Patent Publication No. 297600, the surface accuracy of the imaging optical system of the alignment device, particularly the optical components used for the objective lens, is discussed. A method has been proposed to reduce high-order components of wavefront aberration remaining in the imaging optical system by setting a predetermined standard. That is, according to the method disclosed in this publication, the surface accuracy of an optical component is evaluated by the RMS (root mean square: root mean square) value of the wavefront aberration with respect to the reference surface, and all the optical components constituting the objective lens are evaluated. The average value of the RMS values of all the components of the wavefront aberration of the surface is set to be equal to or less than 0.01 λ (where λ is the central wavelength of the light used). The RMS value of the wavefront aberration of each optical surface used for calculating the average value is the RMS value of the component obtained by subtracting the correctable power component and the negative component from the measured wavefront aberration.

Further, the present applicant has disclosed in Japanese Patent Application Laid-Open No. H11-125255, a method for evaluating the surface accuracy of an optical surface, which measures a wavefront aberration with respect to a reference surface of a test surface, and measures the measured wavefront aberration. The ass residue is obtained by removing the ass component from the above, and the ass residue is fitted with a rotating aspheric surface about the optical axis to remove the rotating aspherical component from the ass residue to obtain a rotating aspheric residue. We have proposed a method for evaluating the surface accuracy of the test surface based on this rotating aspheric residue. Also, in this publication, a wavefront aberration of a surface to be measured with respect to a reference surface is measured, an ass component is removed from the measured wavefront aberration to obtain an ass residue, and the ass residue is non-rotated with respect to the optical axis. By fitting with a spherical surface and fitting a cross-sectional curve including the optical axis of the rotating aspheric surface with a quadratic-quadratic curve with respect to the radius, a quadratic-quadratic curve component is removed from the cross-sectional curve to obtain a secondary-quadratic residue. A method for evaluating the surface accuracy of a test surface based on the secondary and quaternary residues is disclosed. Furthermore, the present applicant has proposed in Japanese Patent Application Laid-Open No. 2000-12491 a method for evaluating the imaging performance of an optical system by expressing wavefront aberration by Zernike's polynomial. I have. According to the method disclosed in this publication, the transmitted wavefront aberration (wavefront aberration measured based on the transmitted light) of the optical system is separated into a rotationally symmetric component, an odd-numbered symmetric component, and an even-numbered symmetric component with respect to the center of the pupil. The imaging performance of the optical system is evaluated based on each component. Specifically, the imaging performance of the optical system is evaluated based on the RMS values of each separated component.

In addition, the present applicant has disclosed in Japanese Patent Application Laid-Open No. 6-30871 (and corresponding US Pat. Nos. 5,696,624, and US Pat. Nos. 5,699,18). No. 3, US Patent 5, No. 72,495, U.S. Pat. No. 5,703,712, and U.S. Pat. No. 5,719,698) disclose the homogeneity of the refractive index of the optical member. We propose a method to evaluate by measuring the wavefront aberration. In this publication, the wavefront aberration due to the refractive index distribution is separated into a power component, a negative component, a rotationally symmetric component after removing the power component, a tilt component, a random component, and the like, and the power component is equivalent to the radius of curvature error of the optical system. It discloses that there is.

Furthermore, the present applicant has disclosed in Japanese Patent Application Laid-Open No. 8-55505 that the wavefront aberration due to the refractive index distribution of an optical member is measured, and the measured wavefront aberration is converted into a rotationally symmetric component and a non-rotationally symmetric component with respect to the optical axis. We propose a method to separate and evaluate the homogeneity of the refractive index of optical members. In addition, this publication separates the measured wavefront aberration into a rotationally symmetric component and a non-rotationally symmetric component with respect to the optical axis before or after correcting the power component, and further separates the rotationally symmetric component into second and fourth order components. We have proposed a method to evaluate the homogeneity of the refractive index of the optical member by making corrections.

In the prior art, for example, by applying the method disclosed in Japanese Patent Application Laid-Open No. 11-297600 to an FIA-based objective lens, the average of the mass-produced FIA-based imaging optical system is improved. The imaging performance (wavefront aberration performance) was improved without fail. However, even if, for example, the RMS values of all the components of the wavefront aberration measured for all the optical surfaces that make up the objective lens satisfy the standard of 0.01 λ, a singular surface that generates a special aberration within it (Details of which will be described in detail in the embodiment), there is a disadvantage that the required standard of the imaging optical system cannot be satisfied.

Also, depending on the design of the optical system, even if the surface accuracy of each optical surface is improved, a higher-order aberration component is newly generated by the operation of driving in the aberration by the optical adjustment, and it is expected that the performance will eventually be improved. There was an inconvenience of not being able to do so. Furthermore, even if the polishing accuracy of each optical surface is improved, if the glass (optical material) forming the optical member has a refractive index distribution, there is a disadvantage that the transmitted wavefront aberration is worsened. Disclosure of the invention The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an objective lens system capable of favorably suppressing the remaining higher order wavefront aberration components, and a method of manufacturing the same.

It is another object of the present invention to provide an observation apparatus capable of favorably suppressing higher-order wavefront aberration components remaining in an imaging optical system including an objective lens system according to the present invention, and a method of manufacturing the same.

It is still another object of the present invention to provide an exposure apparatus including the observation apparatus of the present invention, for example, capable of performing high-precision exposure by aligning a mask and a photosensitive substrate with high accuracy with respect to a projection optical system.

It is another object of the present invention to provide a microdevice manufacturing method capable of manufacturing a good microdevice using the exposure apparatus of the present invention.

In order to solve the above problem, a first invention of the present invention includes, in order from the object side, a first lens group having a positive refractive power, and a second lens group having a negative refractive power, The center thickness of the lens closest to the object side in one lens group is d1, and the air conversion along the optical axis between the object side surface of the lens closest to the object side and the object. When the distance is d 0,

d 1 X d 0 <0. 2

And an objective lens system that satisfies the following condition:

According to a second aspect of the present invention, in the method for manufacturing an objective lens system,

A design step of designing the objective lens system by suppressing at least one of a higher order component of wavefront aberration generated by optical adjustment of the objective lens system and a difference of decentering coma aberration for each wavelength;

Adjusting the optical system of the objective lens system in order to correct aberrations remaining in the assembled objective lens system.

According to a third aspect of the present invention, in the method for manufacturing an objective lens system,

In order to suppress high-order components of wavefront aberration remaining in the objective lens system, while suppressing the wavefront aberration due to the refractive index distribution of each optical member constituting the objective lens system, A manufacturing process of manufacturing each of the optical members, while suppressing a wavefront aberration of each surface of each optical member with respect to a reference surface;

Adjusting the optical system of the objective lens system in order to correct aberrations remaining in the assembled objective lens system. Here, the wavefront aberration of each surface with respect to the reference surface is a wavefront aberration representing surface accuracy of each surface, and is a phase shift of the processed surface with respect to the reference surface when the processed surface is measured using an interferometer. is there.

According to the fourth aspect of the present invention, in order to suppress the wavefront aberration remaining in the objective lens system after the optical adjustment, the wavefront difference due to the refractive index distribution of each optical member constituting the objective lens system is suppressed, and Provided is an objective lens system characterized in that wavefront aberration of each surface of each optical member with respect to a reference surface is suppressed.

According to a fifth aspect of the present invention, there is provided an imaging optical system including the objective lens system according to the first aspect or the objective lens system according to the fourth aspect, wherein an object image formed via the imaging optical system is observed. An observation device characterized by the following.

According to a sixth aspect of the present invention, there is provided an observation apparatus including an imaging optical system including an objective lens system, and observing an object image formed through the imaging optical system.

In order to suppress the wavefront aberration remaining in the imaging optical system after the optical adjustment, the wavefront aberration due to the refractive index distribution of each optical member other than the objective lens system in the imaging optical system is suppressed, and Provided is an observation device characterized in that wavefront aberration of each surface of an optical member with respect to a reference surface is suppressed.

According to a seventh aspect of the present invention, there is provided an observation apparatus including an imaging optical system including an objective lens system, and observing an object image formed through the imaging optical system.

The imaging optical system includes an optical member disposed in an optical path between the objective lens system and the object image,

In order to suppress the wavefront aberration remaining in the imaging optical system after the optical adjustment, the refractive index of each optical member among all the optical members arranged in the optical path between the objective lens system and the object image Provided is an observation apparatus, wherein wavefront aberration due to distribution is suppressed, and wavefront aberration of each surface of each optical member with respect to a reference surface is suppressed. In the sixth and seventh aspects of the present invention, when the imaging optical system forms one or a plurality of intermediate images, it is preferable that the object image is not an intermediate image but a final image. .

According to an eighth aspect of the present invention, in a method for manufacturing an observation apparatus for observing an object image formed through an imaging optical system including an objective lens system, the objective lens system is manufactured by using the manufacturing method of the second aspect. To provide a method for manufacturing an observation device, characterized in that the observation device is manufactured by: According to a ninth aspect of the present invention, there is provided the observation apparatus according to the fifth, sixth, or seventh aspect, and a projection optical system for projecting and exposing a mask pattern onto a photosensitive substrate. An exposure apparatus is provided.

In the tenth aspect of the present invention, an exposure step of exposing the pattern of the mask to the photosensitive substrate using the exposure apparatus of the ninth aspect,

And a developing step of developing the exposed substrate.

According to an eleventh aspect of the present invention, there is provided a method for manufacturing an observation apparatus for observing an object image formed via an imaging optical system including an objective lens system,

Adjusting the optical system of the objective lens system to correct aberrations remaining in the assembled objective lens system.

According to a twelfth aspect of the present invention, there is provided a method of manufacturing an observation apparatus for observing an object image formed via an imaging optical system including an objective lens system,

In order to suppress high-order wavefront aberration components remaining in the objective lens system, while suppressing the wavefront aberration due to the refractive index distribution of each optical member constituting the objective lens system, each surface of each optical member with respect to a reference surface A manufacturing process for manufacturing each of the optical members while suppressing wavefront aberration,

In order to correct aberrations remaining in the assembled objective lens system, the objective lens is corrected. And a method for optically adjusting the lens system.

According to a thirteenth aspect of the present invention, there is provided an observation apparatus manufactured by using the manufacturing method of the twenty-second aspect, and a projection optical system for projecting and exposing a mask pattern onto a photosensitive substrate. An exposure apparatus is provided.

In a fourteenth aspect of the present invention, an exposure step of exposing the pattern of the mask to the photosensitive substrate using the exposure apparatus of the thirteenth aspect,

And a developing step of developing the exposed substrate. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a view schematically showing a configuration of an observation apparatus and an exposure apparatus provided with the observation apparatus according to the embodiment of the present invention.

FIG. 2 is a diagram showing a lens configuration of the objective lens of Example 1 included in the FIA-based alignment device that is the observation device of the present embodiment.

FIG. 3 is a diagram illustrating various aberrations of the objective lens of the first example.

FIG. 4 is a diagram showing a lens configuration of an objective lens of Example 2 included in the FIA system alignment device of the present embodiment.

FIG. 5 is a diagram illustrating various aberrations of the objective lens of the second example.

FIG. 6 is a diagram showing RMS values of higher-order spherical aberration components generated when the center thickness of each lens and the air gap of each lens constituting the objective lens system of the first embodiment are changed. .

FIG. 7 shows the RMS value of the high-order coma aberration component of the wavefront aberration generated when each lens constituting the objective lens system of the first embodiment is decentered along the direction orthogonal to the optical axis. FIG.

FIG. 8 shows the shortest wavelength (530 nm) of the used light among the wavefront aberrations generated when each lens constituting the objective lens system of the first embodiment is decentered along the direction orthogonal to the optical axis. RMS value of the decentered coma component of) and the eccentricity of the longest wavelength (800 nm) of the used light FIG. 9 is a diagram illustrating an absolute value of a difference between a coma aberration component and an RMS value.

FIG. 9 is a flowchart showing a manufacturing flow of each optical member constituting the objective lens system of the present embodiment.

FIG. 10 is a diagram schematically showing a configuration of an interferometer device for measuring a wavefront aberration due to a distribution of a refractive index of an optical member.

FIG. 11 is a diagram schematically showing a configuration of an interferometer device for measuring a wavefront aberration of an optical surface of each optical member with respect to a reference surface.

FIG. 12 is a diagram showing a modification of the flowchart of FIG.

FIG. 13 is a flowchart showing a flow of assembling and optically adjusting each optical member constituting the objective lens system of the present embodiment.

FIG. 14 shows the overall configuration of the objective lens system of the present embodiment assembled.

FIG. 15 is a diagram schematically showing a configuration of an interferometer device for measuring a wavefront aberration remaining in the assembled objective lens system.

FIG. 16 is a diagram showing a modified example of the interferometer device of FIG.

FIG. 17 shows the wavefront aberration corresponding to the actual polished surface in Table 7 in a contour diagram of 0.05 λ.

FIG. 18 is an exaggerated three-dimensional view of the undulation of the actual polished surface in Table 7. FIG. 19 shows the wavefront aberration corresponding to the 30 plane in Table 7 by a contour map of 0.05 λ.

FIG. 20 is an exaggerated three-dimensional view of the swell of the 30 plane in Table 7. FIG. 21 shows the wavefront aberration corresponding to the 30th higher-order coma composite surface in Table 7 by a contour map of 0.005λ.

FIG. 22 is an exaggerated three-dimensional view of the undulation of the 3S higher-order coma composite surface shown in Table 7.

FIG. 23 is a flowchart of a method for obtaining a semiconductor device as a micro device using the exposure apparatus of the present embodiment.

FIG. 24 shows an example of using the exposure apparatus of the present embodiment. 5 is a flowchart of a method for obtaining an indicator element. BEST MODE FOR CARRYING OUT THE INVENTION

The objective lens system of the present invention includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power, and satisfies the following conditional expression (1).

d 1 / d 0 <0. 2 (1)

Here, d l is the center thickness of the lens L1 disposed closest to the object side in the first lens group G1. D O is an air-equivalent distance along the optical axis between the object-side surface of the lens L1 disposed closest to the object and the object.

Conditional expression (1) defines an appropriate range for the ratio of the center thickness of the lens L1 to the WD (work distance) of the objective lens system. As will be described later, when the objective lens system of the present invention is applied to an observation device such as an FIA system alignment device, a prism as a light beam deflecting means is arranged in the optical path between the lens surface closest to the object and the object surface. Is done. Therefore, the required WD is required to secure enough space to place the prism.

Further, in the objective lens system of the present invention, correction of spherical aberration is mainly performed by the lens L 1 arranged closest to the object side, and this lens L 1 has the largest power (refractive power). If the center thickness d l of the lens L 1 increases while maintaining the power required for the spherical aberration, the radius of curvature of the surface of the lens L 1 decreases. On the other hand, as will be described later, the objective lens system of the present invention is required to have a sufficiently small high-order spherical aberration caused by a change in the center thickness of each lens and the air gap of each lens. If the radius of curvature is reduced by increasing the center thickness d 1 of the lens L 1, the angle between the ray incident on the lens 1 and the normal to the lens surface increases, resulting in higher-order spherical aberration caused by an air gap error. Becomes bigger. As described above, by satisfying conditional expression (1), it is possible to satisfactorily correct spherical aberration while securing the required WD, and to suppress the occurrence of higher-order spherical aberration even when decentered.

In the objective lens system according to the present invention, it is preferable that the following conditional expressions (2) to (4) are satisfied. I Re 1—Re 2 | Ku 15 (2)

V 1 <40 (3)

S 2 <40 (4)

Here, R 1 is the Abbe number of the lens on the object side of the pair of lenses arranged closest to the image in the second lens group G2. Re 2 is the Abbe number of the lens on the image side of the pair of lenses.

Conditional expressions (2) to (4) specify the conditions necessary for favorably correcting axial chromatic aberration of the entire objective lens system. In the objective lens system of the present invention, it is required that the axial chromatic aberration be properly corrected over the entire wavelength range of the used light. In addition, as will be described later, it is required that the difference in coma aberration for each wavelength generated due to the eccentricity of each lens component is sufficiently small. The pair of lenses disposed closest to the image in the second lens group G2 is a lens component that emits an on-axis light beam as parallel light in the infinity objective lens system.

Therefore, the image height dependence of the incident light beam and the exit light beam on the pair of lenses is the smallest, and chromatic coma is less likely to occur than other lens components. As described above, by satisfying conditional expressions (2) to (4), it is possible to satisfactorily correct axial chromatic aberration and to suppress chromatic coma even when decentered. In order to achieve the effect of the present invention more favorably, it is preferable to set the upper limit of conditional expression (2) to 10. Further, in order to further suppress the occurrence of chromatic coma upon decentering, it is preferable that the pair of lenses be configured as a cemented lens.

In the objective lens system according to the present invention, it is preferable that the following conditional expression (5) is satisfied.

D / L <0.17 (5)

Here, D is the center thickness of the lens component (including the cemented lens) with the largest negative refractive power. L is the distance along the optical axis between the image side surface of the lens closest to the image side in the second lens group G2 and the object, that is, the total length of the objective lens system.

Conditional expression (5) is based on the relationship between the center thickness of the lens component having the largest negative refractive power and the objective lens. An appropriate range is specified for the ratio to the overall length of the strain. As described above, when the objective lens system of the present invention is applied to an observation device such as an FIA-based alignment device, a prism as a light beam deflecting means is disposed in the optical path between the lens surface closest to the object and the object surface. Is done. As a result, the total length L of the objective lens system is restricted due to the restriction of the WD for arranging the prism.

Further, as described later, in the objective lens system of the present invention, it is required that the amount of high-order coma aberration generated due to the eccentricity of each lens component is sufficiently small. Explaining in accordance with each embodiment described later, the incident height of the light beam incident on the lens unit L5 is reduced so that the amount of high-order aberration generated by the eccentricity of the lens unit L5 closest to the image side is reduced. When the angle with respect to the normal to the lens surface is made as small as possible, the center thickness D of the lens unit L4 increases. Here, the lens unit L4 is a lens component having the largest negative refractive power and mainly corrects coma. If the value falls outside the range of the conditional expression (5), the negative refracting power of the lens unit L4 becomes weak, and it becomes difficult to correct necessary coma. As described above, by satisfying conditional expression (5), the higher-order spherical aberration generated due to the change of the center thickness of each lens and the air gap of each lens, and the higher-order spherical aberration generated by the eccentricity of each lens component The amount of coma can be suppressed well, and the coma can be corrected well.

As described above, according to the present invention, by satisfying the conditional expressions in the above-described basic configuration, it is possible to realize, at a design level, an objective lens system capable of favorably suppressing the remaining higher order components of the wavefront aberration. In the present invention, the remaining wavefront is designed by designing at least one of the differences between the higher-order component of the wavefront aberration generated by the optical adjustment of the objective lens system and the decentering coma aberration for each wavelength. Higher-order aberration components, and thus the entire wavefront aberration, can be favorably suppressed. Further, in the present invention, the wavefront aberration due to the refractive index distribution of each optical member constituting the objective lens system is suppressed, and the wavefront aberration of each surface of each optical member with respect to the reference plane is suppressed, so that each optical member is manufactured. By doing so, it is possible to satisfactorily suppress high-order components of the wavefront aberration remaining in the objective lens system, and hence the wavefront aberration.

Therefore, an object formed via an imaging optical system including the objective lens system of the present invention In an observation apparatus for observing an image, a wavefront aberration component remaining in the objective lens system and, consequently, in the imaging optical system can be favorably suppressed. Further, in the exposure apparatus provided with the observation device of the present invention, for example, the mask and the photosensitive substrate can be aligned with high accuracy with respect to the projection optical system using the observation device to perform favorable exposure. Furthermore, in the method for manufacturing a micro device using the exposure apparatus of the present invention, a good micro device can be manufactured through a good exposure step.

By the way, in embodiments described later, the present invention is described by expressing wavefront aberration by Zernike polynomial. Therefore, the following is a description of the fundamental matters regarding the expression of the wavefront aberration and its components by Zernike polynomials. In the representation of the Zernike polynomial, polar coordinates are used as the coordinate system, and Zernike cylindrical functions are used as the orthogonal function system.

As described in an embodiment described later, when measuring the surface accuracy of an optical surface using an interferometer, the phase shift between the reflected light from the reference Fizeau spherical surface and the reflected light from the optical surface is determined. Measured as wavefront aberration. Also, when measuring the transmitted wavefront aberration of the objective lens system, the reflected light from the reference Fizeau plane (Fizeau flat) is collected once by the objective lens system, reflected by the reflective spherical surface, and returned to the Fizeau plane again. The phase shift with the returned light is measured as wavefront aberration. In either case, the measurement result of the interferometer is represented by the same wavefront aberration function, but the surface measurement directly represents the surface shape error. Here, the most common Fizeau interferometer is described as an example, but an interferometer that can perform the same phase difference measurement, such as a Twyman-Green interferometer, a Mach-Zehnder interferometer, or a shearing interferometer, is used. Alternatively, a wavefront splitting type wavefront aberration measuring device using a microlens array, which has been actively developed in recent years, may be used. Alternatively, the deviation from the reference plane may be measured using a three-dimensional measuring device that directly measures the lens surface by a contact method and measures a three-dimensional structure.

First, the polar coordinates are defined on the exit pupil plane, and the obtained wavefront aberration W is expressed as W (ρ, Θ). Here, / 0 is a normalized pupil half-pupil in which the radius of the exit pupil is normalized to 1, and Θ is a radial angle in polar coordinates. Next, the wavefront aberration W (ρ, Θ) is developed as shown in the following equation (6) using the Zernike cylindrical function system Ζη (ρ, Θ). W (p, Θ) = ∑ Cn Z n (p, Θ)

= C 1Z 1 (p, Θ) + C 2Z 2 (p, Θ)

---· + Cn · Zn (p, Θ) (6) where Cn is an expansion coefficient. Hereinafter, of the Zernike cylindrical function system Zn (p, Θ), the cylindrical function systems Ζ1 to Ζ36 relating to the first to the 36th terms are as follows.

η Ζ η (ρ, θ)

1 1

2 ρ cos θ

3 ίθ sin 6 *

4 ² ρ 2 - 1

5 ρ ² cos 2 θ

6, o ² sin2 θ

^{7 (3 ρ 2 - 2)} pcos 0

^{8 (3 ρ 2 - 2)} ρ sine

9 6 ρ to 6 ρ ² + 1

10 ρ ³ cos 3 θ

11 ρ ³ sin 3 θ

^{12 (4 ρ 2 - 3)} p 2 cos 2 θ

^{13 (4 ρ 2 - 3)} p 2 sin2 θ

^{14 (10 ρ 4 - 1 2} ρ 2 + 3) pcos θ

^{15 (1 0 ρ 4 - 1} 2 2 + 3) psin ^

^{16 20 ρ 6 - 30 ρ +} 1 2 ιθ 2 - 1

17 p ⁴ cos 4 θ

18 P ⁴ sin4 θ

19 (5 ρ ² -4) p ³ cos 3 θ

20 (5! Θ ² — 4) p ³ sin3 θ

^{21 (1 5 ί) 4 -} 20 ρ 2 + 6), o 2 cos2 θ ^{22: (1 5 p 4 -} 20/0 2 + 6) p 2 sin2 Θ

^{23: (35 | 0 6 -} 60 p 4 + 30 p -4) p cos Θ

^{24: (35 p 6 - 60} p + 30 p'-4) psinO

^{25: 70 p 8 - 140 p} 6 + 90 p -20 p 2 + l

26: p "cos 5 Θ

27: p ⁵ sin5 Θ

^{28: (6 p 2 - 5} ) p 4 cos4 Θ

^{29: (6 p 2 - 5} ) p 4 sin4 Θ

30: (1 p-30 p ² + 10) p ³ cos30

^{31: (21 p 4 - 30} p 2 + 1 0) p 3 sin3 Θ

^{32: (56 p 6 - 1} 04 p 4 + 60 p 2 - 10) p 2 cos2 Θ

33: (56 p ⁶ -l 04 p ⁴ + 60 i) ^z -10) p ² sin2 Θ

^{34: (126 p 8 - 280} p 6 + 2 10 p - 60 p 2 + 5) pcos0

35: (126 p ⁸ — 280/0 ⁶ + 2 10 ί) ⁴ — 60/0 ² + 5) psin0

^{36: 252, ο 10 - 630} ί) 8 + 560 ρ 6 - 2 1 0/0 4 + 30, o 2 - l

As described above, the evaluation method based on the wavefront aberration W in the prior art used the maximum-minimum difference (PV value) of all the components W of the wavefront difference and the RMS value as the evaluation index. However, even if the evaluation is made to be the same value by the P-V value and the RMS value of all the components W of the wavefront aberration, depending on the combination of the expansion coefficients C1, 02, Performance may not be achieved. Therefore, in the present invention, each component of the wavefront aberration W is considered.

First, the wavefront aberration W can be classified into a rotationally symmetric component, an odd symmetric component, and an even symmetric component. Here, the rotationally symmetric component is a term that does not include 6 », that is, a rotationally symmetric component in which the value at a certain coordinate and the value at a coordinate obtained by rotating the coordinate by an arbitrary angle around the center of the pupil are equal. Component. An odd symmetric component is a term that includes a trigonometric function that is an odd multiple of the radial angle 0, such as sin0 (or cos0), sin3 Θ (or cos3), that is, the value at a certain coordinate and its value. It is an odd-numbered symmetric component whose coordinates are the same as those at coordinates rotated by an odd fraction of 360 ° around the center of the pupil. Sa Furthermore, the even symmetric component is a term including a trigonometric function that is an even multiple of the radial angle 0, such as sin20 (or cos2 0), sin4 Θ (or cos4 Θ), that is, a value at a certain coordinate, It is an even-symmetric component whose value is the same as the value of the coordinates rotated by an even number of 360 ° around the center of the pupil.

Furthermore, all the components of the wavefront aberration W do not include the terms related to the expansion coefficients C1 to C4 as error components generated at the time of measurement by the interferometer. Here, the first term related to the expansion coefficient C 1 is a constant term. The second and third terms related to the expansion coefficients C 2 and C 3 are the tilt components (X and Y directions). Further, the fourth term related to the deployment coefficient C4 is a power component. In this case, the rotationally symmetric component Wrot, the odd symmetric component Wodd, and the even symmetric component Wevn of the wavefront aberration W are expressed by the following equations (7) to (9), respectively. In the following, for simplicity of expression, the n-th term is expressed in principle by the expansion coefficient Cn of the n-th term. That is, in the following expressions (7) to (9) and expressions of each component, it means Cr ^ iCn * Zn. Wrot (ρ, Θ) = C 9 + C 16 + C 25 + C 36 (7)

Wodd (p, Θ) = C 7 + C 8 + C 10 + C 11 + C 14 + C 15

+ C 19 + C 20 + C 23 + C 24 + C 26

+ C 27 + C 30 + C 31 + C 34 + C 35 (8) Wevn (p, Θ) = C 5 + C 6 + C 12 + C 13 + C 17 + C 18

+ C 2 1 + C 22 + C 28 + C 29 + C 32

+ C 33 (9)

Thus, each component considered in the embodiment described later, that is, all components W, rotationally symmetric component Wrot, rotationally symmetric high-order component Wroth, non-rotationally symmetric component Wrnd, non-rotationally symmetric component after ass correction Wrndmas, ass correction Non-rotationally symmetric high-order component Wrndmash, Longitudinal aberration component W Longitudinal, Longitudinal aberration high-order component W Longitudinal height, Lateral aberration component W Horizontal, High-order lateral aberration component W Lateral height, Correction Wmas, Low-order spherical surface Aberration correction Wmassa, as well as low-order coma aberration correction W mascoina> High-order aberration component Wmassacoma is expressed as follows.

All components: W = Wrot + Wodd + Wevn

Rotationally symmetric component: Wrot (see equation (7)) Rotationally symmetric higher-order components (rotationally symmetric components 2nd and 4th-order residuals): Wroth = Wrot— C 9 Non-rotationally symmetric components: Wrnd = Wodd + Wevn

Non-rotationally symmetric component after phase correction: Wrndmas = Wrnd— C 5 -C 6

Non-rotationally symmetric high-order component after ass correction: Wrndmash = Wrndmas— C 7 -C 8 Longitudinal aberration component: Longitudinal = 1 ”(^ + 6 ¥ 11-5— € 6

Longitudinal aberration higher order component: W vertical height-W vertical one C9

Lateral aberration component: W transverse = Wodd (see equation (8))

Lateral aberration higher order component: W side height-W side one C7—C8

Correction: Wmas = W— C 5— C 6

And low order spherical aberration correction: Wmassa = W— C 5— C 6— C 9

And low-order coma aberration correction: Wmascoma = W— C 5-C 6 -C 7 -C 8 High-order aberration component: Wmassacoma = W— C 5 -C 6-C 7-C 8-C 9 The component W is a component obtained by correcting the tilt component and the power component from the wavefront aberration of each surface with respect to the reference surface. The rotationally symmetric higher-order component Wroth is the rotationally symmetric component second-order fourth-order residual obtained by removing the quadratic-quadratic curve component from the rotationally symmetric component Wr 01. Furthermore, the non-rotationally symmetric component Wrndmas after the ass correction is the non-rotationally symmetric component after the ass component has been corrected from all components W.

Further, the gas correction Wmas is a component obtained by correcting the gas component from all the components W. Further, the ass and low-order spherical aberration correction Wmassa are components obtained by correcting the ass component and the low-order spherical aberration component from all the components W. The as and low-order coma aberration correction W mascoma is a component obtained by correcting the as-component and the low-order coma component from all the components W. Here, the ass component is a wavefront aberration component proportional to the square of the distance from the optical axis on a certain meridional surface, and a wavefront aberration component proportional to the square of the distance from the optical axis on a surface orthogonal to the meridional surface. This is the component with the largest difference.

Also, when the root mean square (RMS value) of each wavefront aberration component is expressed with R before RWrot, and the RMS value for each term of the Zernike polynomial is similarly expressed with R before RCn, The following relationship is established.

Rotationally symmetric components: (RWrot) ² = (RC 9) ² + (RC 16) ² + (RC 25) ² + (RC 36) ² Odd symmetric component:

(RWodd) ² = (RC 7) ² + (RC 8) ² + (RC 10) ² + (RC 1 1) ²

+ (RC 1) ² + (RC 15) ² + (RC 19) ² + (RC 20) ² + (RC 23) ² + (RC 24) ² + (RC 26) ² + (RC 27) ² + (RC 30) ² + (RC 3 1) ² + (RC 34) ² + (RC 3 5) ² Even symmetric components:

(RWevn) ² = (RC 5) ² + (RC 6) ² + (RC 1 2) ² + (RC 13) ²

^{+ (RC 17) 2 + (} RC 1 8) 2 + (RC 2 1) 2 + (RC 22) 2 + (RC 28) 2 + (RC 29) 2 + (RC 32) 2 + (RC 3 3) ² All components: (RW) ² = (RWrot) ² + (RWodd) ² + (RWevn) ²

Rotationally symmetric component: (RWrot) ²

Rotationally symmetric components higher order (second order fourth order residual):

(R Wroth) ² = (RWrot) ^2- (RC 9) ²

Non-rotationally symmetric component: (RWrnd) ² = (RWodd) ² + (RWevn) ²

Non-rotationally symmetric component after phase correction:

(RWrndmas) ² = (RWrnd)-(RC 5) ^2- (RC 6) ²

Non-rotationally symmetric higher-order components after phase correction:

(RWrndmash) ² = (RWrndmas) ^2- (RC 7) ² — (RC 8) ²

Longitudinal aberration component:

(RW vertical) ² = (RWrot) ² + (RWevn) ² — (RC 5) ² — (RC 6) ² Longitudinal aberration higher order component: (RW vertical) ² = (RW vertical) ² — (RC 9) ^Two

Lateral aberration component: (RW side) ² = (R Wodd) ²

Lateral aberration higher order component: (RW lateral height) ² = (RW lateral) ² — (RC 7) ² — (RC 8) ² Error correction: (RWmas) ² = (RW) ² — (RC 5) ² — (RC 6) ²

And low-order spherical aberration correction:

(RWmas sa) ² = (RW) ² — (RC 5) ² — (RC 6) ² — (RC 9) ² fs and low order coma correction: (RWmascoma) ² = (RW) ^2- (RC 5) ^2- (RC 6) ^2- (RC 7) ²

One (RC 8) ²

Higher order aberration components:

(RWmassacoma) ² = (RW) ^2- (RC 5) ^2- (RC 6) ^2- (RC 7) ²

(RC 8) ² — (RC 9) ² An embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a view schematically showing a configuration of an observation apparatus and an exposure apparatus provided with the observation apparatus according to the embodiment of the present invention. In the present embodiment, the present invention is applied to a FIA-based alignment device as an observation device for detecting the position of a photosensitive substrate in an exposure device. In FIG. 1, the Z axis is parallel to the optical axis of the projection optical system PL of the exposure apparatus, and the X axis is perpendicular to the paper plane of FIG. 1 in a plane perpendicular to the Z axis, and the Z axis is perpendicular to the Z axis. The Y-axis is set in a direction perpendicular to the plane of FIG.

The illustrated exposure apparatus includes an exposure illumination system (not shown) for uniformly illuminating a reticle R as a mask (projection master) with appropriate exposure light. The reticle R is supported on the reticle stage 1 substantially parallel to the XY plane, and a circuit pattern to be transferred is formed in the pattern area PA. The light illuminated by the exposure illumination system and transmitted through the reticle R reaches the wafer W via the projection optical system PL, and a pattern image of the reticle R is formed on the wafer W. Incidentally, the wafer W is _c Z stage 2 2, which is substantially parallel to the support to the XY plane on a Z stage 2 2 via the Wehahoru da 2 1, the stage control system 2 4, the optical axis of the projection optical system PL It is configured to be driven along.

Further, the Z stage 22 is supported on the XY stage 23. The XY stage 23 is also configured to be driven two-dimensionally in the XY plane perpendicular to the optical axis of the projection optical system PL by the stage control system 24. As described above, in the exposure apparatus, prior to the projection exposure, it is necessary to optically align the pattern area PA on the reticle R with each of the exposure areas on the ゥ: [: C W. It is necessary. Therefore, an X-axis position and a Y-axis position of a wafer mark WM in a reference coordinate system, which is an alignment mark formed of a pattern (eg, a step pattern) formed on the wafer W, are detected, and the alignment is performed based on the position information. Is performed.

Note that the wafer mark WM is a two-dimensional mark having periodicity in the X and Y directions, even if it is two independent one-dimensional marks having periodicity in the X and Y directions, respectively. Is also good. The FIA-based alignment device shown in FIG. 1 includes a light source 3 for supplying alignment light AL as illumination light having a wide wavelength bandwidth. As the light source 3, for example, a light source such as a halogen lamp can be used. In the present embodiment, the wavelength band of the alignment light is, for example, 530 nm to 800 nm. The alignment light AL from the light source 3 enters a light guide 4 such as an optical fiber via a relay optical system (not shown), and propagates through the inside. The alignment light A L emitted from the exit end of the light guide 4 is restricted via, for example, an illumination aperture stop 27 having a circular opening, and then enters a condenser lens 29.

The alignment light A L via the condenser lens 29 is once condensed, and then enters the illumination relay lens 5 via an illumination field stop (not shown). The alignment light AL converted into parallel light via the illumination relay lens 5 passes through the half prism 6 and then enters the objective lens 7. The alignment light AL condensed by the objective lens 7 is reflected by the reflecting surface of the reflecting prism 8 downward in the figure, and then illuminates the wafer mark WM formed on the wafer W. Thus, the light source 3, light guide 4, illumination aperture stop 27, condenser lens 29, illumination field stop (not shown), illumination relay lens 5, half prism 6, objective lens 7, and reflection prism 8 The illumination optical system is configured to illuminate the wafer mark WM by epi-illumination.

The reflected light (including the diffracted light) from the wafer mark WM with respect to the illumination light enters the half prism 6 via the reflecting prism 8 and the objective lens 7. The light reflected upward in the drawing at the half prism 6 forms an image of the wafer mark WM on the index plate 12 via the second objective lens 11. The light from this mark image is relay lens The light enters the XY-branch half prism 15 via the system (13, 14) and the image forming aperture stop 30 arranged in a position optically substantially common to the illumination aperture stop 27 in the optical path. The light reflected by the XY branch half prism 15 is incident on the CCD 16 for Y direction, and the light transmitted through the XY branch half prism 15 is incident on the CCD 17 for X direction.

Thus, reflecting prism 8, objective lens 7, half prism 6, second objective lens 11, indicator plate 12, relay lens system (13, 14), imaging aperture stop 30, and half prism 15 Constitutes an imaging optical system for forming a mark image based on reflected light from the wafer mark WM with respect to the illumination light. Thus, a mark image is formed on the imaging surface of the Y-direction CCD 16 and the X-direction CCD 17 together with the index pattern image of the index plate 12. Output signals from the Y-direction CCD 16 and the X-direction CCD 17 are supplied to a signal processing system 18. Further, the position information of the wafer mark WM obtained by the signal processing (waveform processing) in the signal processing system 18 is supplied to the main control system 25.

The main control system 25 detects the X-direction position and the Y-direction position of the wafer W based on the position information of the wafer mark WM from the signal processing system 18, and responds to the detected X-direction position and Y-direction position of W. A stage control signal is output to the stage control system 24. The stage control system 24 appropriately drives the XY stage 23 according to the stage control signal to perform the alignment of the wafer W. As described above, the CCD 16 for the Y direction, the CCD 17 for the X direction, the signal processing system 18, and the main control system 25 transmit the wafer W based on the position information of the mark image formed via the imaging optical system. It constitutes a photoelectric detecting means for detecting the position.

[First embodiment]

FIG. 2 is a diagram showing a lens configuration of the objective lens of Example 1 included in the FIA-based alignment device that is the observation device of the present embodiment. As shown in FIG. 2, the objective lens 7 of the first embodiment includes, in order from the object side (that is, the wafer mark WM side), a first lens group G1 having a positive refractive power and a negative refractive power. Second lens group G 2 It is composed of Here, the first lens group G 1 includes, in order from the object side, a biconvex lens L 1, a negative meniscus lens having a convex surface facing the object side, a biconvex lens, and a negative meniscus lens having a concave surface facing the object side. It is composed of a cemented lens L2 formed by bonding and a cemented lens L3 formed by bonding a biconvex lens and a biconcave lens.

The second lens group G2 includes, in order from the object side, a cemented lens L4 formed by bonding a positive meniscus lens having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side, and a biconcave lens. It is composed of a cemented lens L5 formed by bonding L51 and a biconvex lens L52. Note that a reflecting prism 8 is arranged in the optical path between the objective lens 7 and the wafer mark WM.

Table 1 below shows values of specifications of the objective lens of the first example. In Table 1, f is the focal length of the objective lens, NA is the object side numerical aperture of the objective lens, and d O is the air along the optical axis between the most object side lens surface and the object surface of the objective lens. The converted distances are shown respectively. Also, the surface number is the order of the surfaces from the wafer side along the direction in which the light beam travels from the object surface, i.e., plane 8 to the image surface, r is the radius of curvature (mm) of each surface, and d is The on-axis spacing of each surface, that is, the surface spacing (mm), n is the refractive index for the d-line (wavelength λ = 57.67.6 nm), and Li is the Abbe number. In each embodiment, the distance from the object surface (wafer surface) to the object-side surface of the lens L1 is 48.5 mm, and the thickness is 28 mm and the refractive index is 1.56 8 8 3 The glass block (corresponding to the reflective prism 8) with Abbe number 56.05 is arranged. In Table 1 and (2) below, the distance from the object plane to the object-side surface of the lens L1 is shown in terms of air equivalent length. The following aberrations in FIGS. 3 and 5 show aberrations of the optical system including the glass block. Table 1

(Main specifications)

f = 30.0 mm

NA = 0.3 (Optical component specifications)

Surface number r d n

(Wafer surface) 38.3

1 201.94 5.0 1.74443

L 1)

2 -37.92 0.1

3 151.01 4.0 1.71700 nds L 2)

4 29.52 9.5 1.49782 82.52

5 -27.11 3.0 1.61266 44.41

6 -87.01 0.2

7 31.19 8.5 1.49782 3)

CO / L

8 -32.63 4.0 1.52682 51.35

9 167.46 1.5

One

10 28.49 8.0 1.9782

11 114.92 10.7 1.67163 38.80

12 15.00 7.0

13 -15.44 6.2 1.65128

(L5)

14 331.20 10.8 1.71736 29.46

15 -27.17

(Values for conditional expressions)

d 1 = 5.0 mm (lens 1)

d 0 = 2 8 / 1.5 6 8 8 3 + (4 8.5--28) / 1

3 8.347 mm

D = 18.7 mm (Lens L 4)

L = 1 2 7 mm

(1) d l d 0 = 0.13

(2) 1 v 1-v 2 | = 8.7 2 (3) D 1 = 38.18 (Lens L 51)

(4) v 2 = 29.46 (lens 52)

(5) D / L = 0.147 FIG. 3 is a diagram showing various aberrations of the objective lens of the first example. In each aberration diagram, FN〇 is the F-number, Y is the image height, e is the e-line (wavelength 546.1 nm), C is the C line (wavelength 656.3 nm), and A is the A line ( The wavelength is 78.2 nm). Further, in the aberration diagram showing astigmatism, a solid line indicates a sagittal image plane, and a broken line indicates a meridional image plane. As is clear from the aberration diagrams, it can be seen that the objective lens of the first embodiment has excellent imaging performance at the design level in which various aberrations including chromatic aberration are well corrected.

[Second embodiment]

FIG. 4 is a diagram showing a lens configuration of the objective lens of Example 2 included in the FIA-based alignment device that is the observation device of the present embodiment. As shown in FIG. 4, the objective lens 7 of the second embodiment includes, in order from the object side, a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power. It is configured. Here, the first lens group G1 is composed of, in order from the object side, a biconvex lens Ll, a negative meniscus lens having a convex surface facing the object side, a biconvex lens, and a negative meniscus lens having a concave surface facing the object side. It is composed of a cemented lens L2 and a cemented lens L3 formed by laminating a bifocal lens and a biconcave lens.

Table 2 below gives data of the specifications of the objective lens of the second example. In Table 2, f is the focal length of the objective, NA is the object-side numerical aperture of the objective, and d0 is the objective. The air-equivalent distance along the optical axis between the lens surface closest to the object side of the lens and the object surface is shown. The surface number is the order of the surface from the wafer side along the direction in which the light beam travels from the wafer surface, which is the object surface, to the image surface, r is the radius of curvature (mm) of each surface, and d is each surface Is the on-axis spacing, ie, the plane spacing (mm), n is the refractive index for the d-line (wavelength λ = 587.6 nm), and R is the Abbe number. Table 2

(Main specifications)

f = 30.0 mm

NA = 0.3

(Optical component specifications)

Surface number r d n V

(8 sides) 38.3

1 367, .86 5.0 1., 74443 49.52 (Lens L 1)

2-37, .33 0.1

3 89, .88 4.0 1., 67163 38.80 (Lens L 2)

4 30, .92 9.5 1., 49782 82.52

5 -30, .42 3.0 1., 61266 44.41

6 -740. .30 0.2

7 34. .75 8.0 1.49782 82.52 (Lens L 3)

8 -30, .86 4.0 1.52682 51.35

9 -239. .23 0.2

10 19, .14 8.6 1. 49782 82.52 (Lens L4)

11 68., 11 5.0 1. 61 266 44.41

12 11. .63 5.5

13 -18. .46 10.0 1. 65 128 38.18 (Lens L 5)

14 34. .04 10.5 1. 72825 28.34 15 -41.13 (Value for conditional expression)

d 1 = 5.0mm (lens 1)

d 0 = 28 / 1.56883 + (48.5-28) / 1

= 38.347 mm

D = 13.6 mm (Lens L 4)

L = 122. lmm

(1) d 1 / d 0 = 0.13

(2) I v 1-v 2 1 = 9.84

(3) v 1 = 38.18 (Lens L 5 1)

(4) v 2 = 28.34 (lens 52)

(5) D / L = 0.11 1 FIG. 5 is a diagram showing various aberrations of the objective lens of the second example. In each aberration diagram, F NO is the F number, Y is the image height, e is the e-line (wavelength 546.1 nm), C is the C line (wavelength 656.3 nra), and A is the A line ( The wavelength is 78.2 nm). Further, in the aberration diagram showing astigmatism, a solid line indicates a sagittal image plane, and a broken line indicates a meridional image plane. As is clear from the aberration diagrams, similarly to the first embodiment, the objective lens of the second embodiment has excellent correction of various aberrations including chromatic aberration at the design level, and has excellent imaging performance. Understand.

Next, a method for manufacturing the objective lens system (that is, the objective lens 7) of the present embodiment, and further, a method for manufacturing the observation device (that is, the FIA-based alignment device) will be described. In general, aberrations in an objective lens system and the like are caused by non-uniformity of the refractive index distribution of an optical material (glass material) and a polished surface error. However, even if there is no non-uniformity of the refractive index distribution and no polished surface error, errors in the center thickness and air gap of each lens and errors in the eccentricity of lens components in the direction perpendicular to the optical axis will occur during manufacturing. appear. In the objective lens system, errors in the center thickness and air gap of each lens As a result, spherical aberration mainly occurs, and decentering error mainly causes coma. Here, low-order components of spherical aberration and coma can be corrected by optical adjustment, but high-order components of spherical aberration and coma are difficult to correct by optical adjustment. Also, if the decentering coma aberration differs for each wavelength in the wavelength range used, coma due to color remains, which is also difficult to correct by optical adjustment. From this point of view, not only is the optical system itself sufficiently corrected for aberrations at the design level, but it is also designed to prevent the generation of unadjustable high-order wavefront aberration components even if the lens is moved during optical adjustment. Is important. Therefore, in the present embodiment, the objective lens system is designed such that the higher order components of wavefront aberration and the eccentric coma for each wavelength, which are generated by the optical adjustment of the objective lens system, are not more than predetermined values.

Specifically, when the numerical aperture on the object side of the objective lens 7 is NA and the center wavelength of the light used (that is, the wavelength of the C-line: 656.3 nm) is λ, each of the constituent elements of the objective lens 7 is The RMS (root mean square) value of the higher order spherical aberration component of the wavefront aberration generated when the center thickness of the lens and the air spacing of each lens are changed by d (mm), respectively, is (30 · d · NA ⁶ ) · λ 1 or less. Here, the RMS value of the higher order spherical aberration component is obtained based on the 16th term of the Zernike polynomial.

FIG. 6 is a diagram showing RMS values of higher-order spherical aberration components generated when the center thickness of each lens and the air gap of each lens constituting the objective lens system of the first embodiment are changed. . In Figure 6, the vertical axis indicates RM S values of higher-order spherical aberration component generated is in multiples of ^{(d · ΝΑ 6) · λ} 1. Referring to FIG. 6, in the reference example according to the prior art, the RMS value of the higher-order spherical aberration component partially exceeds (30 · d · NA ⁶ ) · λ1, but the RMS value of the first embodiment is In the objective lens 7 (Example in FIG. ⁶ ), it can be seen that the RMS value of the higher-order spherical aberration component is set to (30 · d · NA ⁶ ) · λ1 or less throughout. Although not shown, also in the objective lens 7 of the second embodiment, the RMS value of the higher-order spherical aberration component is set to (30 · d · NA ⁶ ) · λ1 or less throughout.

Further, in the present embodiment, each lens constituting the objective lens 7 is The RMS value of the higher-order coma difference component of the wavefront aberration that occurs when the beam is decentered by s (mm) along the direction is set to (50 · s · NA ⁵ ) · λ1 or less. Here, the RMS value of the higher-order coma aberration component is obtained based on the 14th term of the Zernike polynomial.

FIG. 7 shows RMS values of higher-order coma aberration components among wavefront aberrations generated when each lens constituting the objective lens system of the first embodiment is decentered along a direction orthogonal to the optical axis. FIG. In Figure 7, the vertical axis, RM S values of high-order coma aberration components generated indicates a has many times the ^{(s · ΝΑ 5) · λ} 1. If you see FIG. 7, in the reference example according to the prior art, although the RMS value of the high-order coma aberration component greatly exceeds the partially ^{(50 · s · ΝΑ 5)} · λ 1, first embodiment examples in the objective lens 7 (the seventh FIG example), it can be seen that the RMS value of the high-order coma aberration components is set to Wataru connexion ^{(5 0 · s · ΝΑ 5} ) · λ 1 below throughout. Although not shown, in the objective lens 7 in the second embodiment, RMS value of the high-order coma aberration components is set to Wataru connexion ^{(50 · s · ΝΑ 5)} · λ 1 below throughout.

Further, in the present embodiment, among the wavefront aberrations generated when each lens constituting the objective lens 7 is decentered by s (mm) along the direction orthogonal to the optical axis, the decentering coma aberration of the shortest wavelength of the used light is used. The absolute value of the difference between the RMS value of the component and the RMS value of the decentered coma component of the longest wavelength of the used light is set to (50 · s · NA ³ ) · λ1 or less. Here, the absolute value of the difference between the RMS value of the eccentric coma component of the shortest wavelength of the used light and the RMS value of the eccentric coma component of the longest wavelength of the used light is obtained based on the seventh term of the Zernike polynomial. .

FIG. 8 shows the shortest wavelength (530 nm) of the used light among the wavefront aberrations that occur when each lens constituting the objective lens system of the first embodiment is decentered along the direction orthogonal to the optical axis. FIG. 9 is a diagram showing an absolute value of a difference between an RMS value of an eccentric coma aberration component and an RMS value of an eccentric coma aberration component of the longest wavelength (800 nm) of light used. In FIG. 8, the vertical axis represents the absolute value of the difference between the RMS value of the shortest wavelength eccentric coma component of the used light and the RMS value of the longest wavelength eccentric coma component of the used light (s-NA ³ ) · Indicates how many times λ 1 is. Referring to FIG. 8, a reference example according to the prior art is shown. The absolute value of the difference between the RMS value of the decentered coma component of the shortest wavelength of the used light and the RMS value of the decentered coma component of the longest wavelength of the used light is partially (50 · s · NA ³ ) · λ Although it greatly exceeds 1, the RMS value of the shortest wavelength decentered coma component of the used light and the decentered comatic aberration component of the longest wavelength of the used light in the objective lens 7 of the first embodiment (the embodiment in FIG. 8) it can be seen that the absolute value of the difference between the RMS value of is set to Wataru connexion ^{(50 * s * NA 3)} * a l or less throughout. Although not shown, also in the objective lens 7 of the second embodiment, the difference between the RMS value of the decentered coma component of the shortest wavelength of the used light and the RMS value of the decentered coma aberration component of the longest wavelength of the used light is shown. Is set to (50 · s · NA ³ ) · λ1 or less throughout.

Next, each optical member (that is, each lens) of the objective lens 7 of the present embodiment designed as described above is manufactured. FIG. 9 is a flowchart showing a manufacturing flow of each optical member constituting the objective lens system of the present embodiment. In the manufacturing process of each optical member, as shown in FIG. 9, a block glass material (blanks) for forming each optical member is manufactured (S11). Then, the homogeneity of the refractive index of the manufactured block glass material is inspected (S12). Specifically, the distribution of the refractive index of the block glass material is measured using the interferometer shown in FIG. In FIG. 10, a block glass material 103 as a test object is set at a predetermined position in a sample case 102 filled with oil 101.

Then, the emission light from the interferometer unit 105 controlled by the control system 104 is incident on a Fizeau flat (Fiso one plane) 106 supported on the Fizeau stage 106a. Here, the light reflected by the Fizeau flat 106 becomes reference light and returns to the interferometer unit 105. On the other hand, the light transmitted through the Fizeau flat 106 becomes measurement light and is incident on the test object 103 in the sample case 102. The light transmitted through the test object 103 is reflected by the reflection plane 107 and returns to the interferometer unit 105 via the test object 103 and the Fizeau flat 106. In this way, based on the phase shift between the reference light and the measurement light returned to the interferometer unit 105, the wavefront aberration due to the refractive index distribution of each block glass material 103, and thus the wavefront aberration due to the refractive index distribution of each optical member, is measured. You. The details of the measurement of refractive index homogeneity by an interferometer are described in, for example, Japanese Patent Application Laid-Open No. 8-5505 (and corresponding US Pat. No. 181, 469). Here, U.S. Patent No. 6,025,955 and U.S. Patent No. 6,181,469 are incorporated by reference.

In the present embodiment, a standard regarding the refractive index homogeneity of the optical member is set. In this standard, the PV value (peak to valley: difference between maximum and minimum) of the wavefront aberration due to the refractive index distribution of each optical member is set to 0.005λ or less. Here, λ is the wavelength of the measurement light of the wavefront aberration. In the case of a normal interferometer, λ = 632.8 nm because a He-Ne laser is used. In the present embodiment, since the He-Ne laser is also used in other interferometer devices, λ is 632.8 nm in other standards described later.

For each optical member that does not pass the inspection in accordance with the above-mentioned standard regarding refractive index homogeneity, it is discarded by sorting, or production of block glass material is attempted again to improve quality. Next, each optical member is polished to reduce the surface accuracy of the optical surface to a standard value (S13). In the present embodiment, the following four standards are provided in parallel with respect to the surface accuracy of the optical surface of each optical member constituting the objective lens system.

The first standard for the surface accuracy of the optical surface of each optical member is that the RMS value of all components W after correcting the tilt component and the power component from the wavefront aberration with respect to the reference surface of each surface of each optical member is 0.001. It is set to λ or less. Also, the RMS value of the rotationally symmetric component Wrot of all components W is set to 0.005λ or less. In addition, the RMS value of the rotationally symmetric component second-order and fourth-order residual Wroth obtained by removing the second-order and fourth-order curve components from the rotationally symmetric component Wrot is set to 0.003λ or less. In addition, the RMS value of the non-rotationally symmetric component Wrndmas after correcting the negative component from all components W is set to 0.005 λ or less. In the second standard regarding the surface accuracy of the optical surface of each optical member, the RMS value of all components W after correcting the tilt component and the power component from the wavefront aberration with respect to the reference surface of each surface of each optical member is set to 0. 010 λ or less. The longitudinal RMS value of the longitudinal aberration component W of all components W is set to 0.0007λ or less. In addition, the RMS value of the longitudinal height of the high order component W of all components W is set to 0.005 λ or less. In addition, the RMS value of the transverse aberration component W of all components W is set to 0.005λ or less. In addition, all ingredients Lateral aberration high-order component of W The RMS value of the W lateral height is set to 0.003λ or less.

In the third standard regarding the surface accuracy of the optical surface of each optical member, the RMS value of all components W after correcting the tilt component and the power component from the wavefront aberration with respect to the reference surface of each surface of each optical member is set to 0. It is set to 0 1 0 λ or less. Also, the RMS value of the component Wmas after correcting the negative component from all the components W is set to 0.008 λ or less. Further, the RMS value of the component Wmas sa after correcting the ass component and the low-order spherical aberration component from all the components is set to 0.005λ or less. The RMS value of the high-order aberration component W massacoma of all components W is set to 0.003λ or less.

In the fourth standard regarding the surface accuracy of the optical surface of each optical member, the RMS value of all components W after correcting the tilt component and the power component from the wavefront aberration with respect to the reference surface of each surface of each optical member is set to 0. It is set to 0 1 0 λ or less. The value of the expansion coefficient C9 of the ninth term when the wavefront aberration is represented by Zernike polynomials is set to 0.009λ or less. Further, the values of the expansion coefficients C10 to C36 of the 10th to 36th terms are set to 0.005? Or less, respectively.

Referring to FIG. 9, the surface accuracy of the polished optical member is inspected using an interferometer (S14). Specifically, the surface accuracy of the optical surface of each optical member is measured using the interferometer shown in FIG. In FIG. 11, light emitted from the interferometer unit 112 controlled by the control system 111 enters the Fizeau lens 113 supported on the Fizeau stage 113a. Here, the light reflected on the reference surface (one Fize surface) of the Fizeau lens 1 13 becomes the reference light, and returns to the interferometer unit 1 12. On the other hand, the light transmitted through the Fizeau lens 113 becomes measurement light and is incident on the optical surface of the lens 114 to be measured. The measurement light reflected from the optical surface to be inspected of the lens to be inspected 1 14 returns to the interferometer unit 1 12 via the Fizeo-lens 1 13. In this way, based on the phase shift between the reference light and the measurement light returned to the interferometer unit 112, the wavefront aberration of the test optical surface of the test lens 114 with respect to the reference surface is measured. Although FIG. 11 shows the Fizeau lens 113 as a single lens, the actual Fizeau lens is composed of a plurality of lenses (lens groups).

One standard arbitrarily selected from the first to fourth standards for surface accuracy described above For each optical component that does not pass the inspection, for example, according to the 4th standard, try additional polishing or change the polishing process and try a new polishing. Next, a coating is applied to the optical surface of each optical member (S15). Thus, each optical member constituting the objective lens system of the present embodiment is completed (S16). As shown in FIG. 12, after the coating (S15), an optical surface inspection (S15 ') by an interferometer can be performed.

FIG. 13 is a flowchart showing a flow of assembling and optically adjusting each optical member constituting the objective lens system of the present embodiment. FIG. 14 is a diagram showing the overall configuration of the assembled objective lens system of the present embodiment. In FIG. 14, the lens components L1 to L5 are incorporated in the lens barrel MT while being held by the corresponding lens chambers LC1 to LC5. It should be noted that a separating ring SA is provided between the lens chamber L C3 holding the lens component L 3 and the lens chamber L C holding the lens component L 4. The lens barrel MT is provided with, for example, an eccentricity adjusting screw V S5 for adjusting the eccentricity of the lens component L5. Although not shown, eccentricity adjusting screws V S1 to V S4 for adjusting the eccentricity of the other lens components L 1 to L 4 are also provided as necessary.

On the other hand, referring to FIG. 13, each lens component is inserted into each lens chamber as a hardware, and the eccentricity is adjusted so that there is no eccentricity to each lens chamber (S21). Then, each lens component is incorporated into the lens barrel while being held by the lens chamber (S22). In this state, the transmitted wavefront aberration (wavefront aberration based on the transmitted light) of the objective lens system is measured using an interferometer, and an inspection is performed in accordance with the later-described standard (S23). Specifically, the wavefront aberration remaining in the assembled objective lens system is measured using the interferometer shown in FIG. In FIG. 15, the light emitted from the interferometer unit 152 controlled by the control system 151 enters the Fizeau flat 153 supported on the Fizeau stage 153a. Here, the light reflected by the Fizeau flat 15 3 becomes the reference light, and returns to the interferometer unit 15 2.

On the other hand, the light transmitted through the Fizeau flat 153 becomes measurement light, and enters the objective lens system 154, which is the test optical system. Measurement light transmitted through the optical system under test 15 4 is reflected The light enters the reflective spherical unit 156 via a parallel flat plate 155 having an optical path length corresponding to the prism 8. The measurement light reflected by the reflective spherical unit 156 returns to the interferometer unit 152 via the parallel flat plate 155, the test optical system 154 and the Fizeau flat 153. In this way, based on the phase shift between the reference light and the measurement light returned to the interferometer unit 152, the wavefront aberration remaining in the objective lens system 154, which is the test optical system, is measured.

In the interferometer shown in FIG. 15, the objective lens system 154 and the reflecting spherical unit 156 are provided by interposing a parallel plane plate 155 having an optical path length corresponding to the reflecting prism 8. Are arranged along a linear optical axis. However, as shown in FIG. 16, a reflecting prism 161 having a shape corresponding to the reflecting prism 8 can be provided instead of the parallel plane plate 1555. However, in this case, the objective lens system 154 and the reflecting spherical unit 156 cannot be arranged along the linear optical axis due to the deflecting action of the reflecting prism 161. As a result, a support 162 for the objective lens system 15 4 and the reflecting prism 16 1 is required, and the objective lens system 15 4, the reflecting prism 16 1 and the reflecting spherical unit 15 6 Alignment is more difficult than with the interferometer device of Fig. 15. However, if the reflecting prism 16 1 and the support 16 2 are actually used parts, the manufacturing error of the reflecting prism 16 1 and the mounting error on the support 16 2 May occur. In this case, it is possible to adjust the wavefront aberration generated by these errors (adjustment of low-order aberration components). For example, when low-order spherical aberration is slightly generated due to an error in the optical path length of the reflecting prism, or when the reflecting prism is tilted or the entire reflecting prism is tilted, low-order coma aberration is reduced. May occur slightly. Such aberrations are preferably corrected by adjusting the objective lens system.

By the way, in the present embodiment, the following three standards are concurrently provided for the optical performance of the objective lens system. In the first standard regarding the optical performance of the objective lens system, the RMS value of all components W after correcting the tilt component and the power component from the wavefront aberration remaining in the objective lens system is set to 0.012λ or less. ing. Also, the RMS value of the rotationally symmetric component Wrot of all components W is set to 0.007λ or less. In addition, The RMS value of the rotational symmetric component W roth obtained by removing the quadratic and quartic curve components from the rotationally symmetric component Wrot is set to 0.005 λ or less. In addition, the RMS value of the non-rotationally symmetric component Wrndmas after correcting the gas component from all components W is set to 0.005λ or less.

In the second standard regarding the optical performance of the objective lens system, the RMS value of all components W after correcting the tilt component and the power component from the remaining wavefront aberration is set to 0.012λ or less. Also, the longitudinal RMS value of the longitudinal aberration component W of all components W is set to 0.008 λ or less. In addition, the RMS value of the vertical order high order component W of all components W is set to 0.006λ or less. Further, the RMS value of the transverse aberration component W of all the components W is set to 0.005 λ or less. Further, the RMS value of the lateral component W lateral height of all components W is set to 0.004λ or less.

In the third standard regarding the optical performance of the objective lens system, the RMS value of all the components W after correcting the tilt component and the power component from the remaining wavefront aberration is set to 0.012λ or less. In addition, the RMS value of the component Wmas after correcting the negative component from all the components W is set to be equal to or less than 0.010λ. In addition, the RMS value of the component Wmassa after correcting the positive component and the low-order spherical aberration component from all the components W is set to 0.008λ or less. Also, the RMS value of the high-order aberration component Wmassacoma of all components W is set to 0.0007λ or less.

In the supplementary standard for the optical performance of the objective lens system, the RMS value of all components W after correcting the tilt component and power component from the remaining wavefront aberration is set to 0.012λ or less. The value of the expansion coefficient C9 in the ninth term is set to 0.009λ or less. In addition, the values of the expansion coefficients C10 to C36 in the tenth to thirty-sixth terms are set to 0.008 λ or less, respectively. This auxiliary standard is an auxiliary standard for the above-mentioned first to third standards. In other words, in the above-described inspection step S23, the power of performing the inspection in accordance with one standard arbitrarily selected from the first to third standards regarding the optical performance of the objective lens system is set. It is preferable to satisfy the above at the same time.

Referring to FIG. 13, the standard regarding the optical performance of the objective lens system (ie, the performance If the inspection fails (indicated by NG in the figure) in the light of the standards selected arbitrarily from the first to third standards and, if necessary, auxiliary standards, as shown in Fig. 14 Adjust the eccentricity by changing the spacing ring SA and the eccentricity adjusting screw VS5 (S24). In this way, after assembling the components as necessary (S22), the transmitted wavefront aberration of the objective lens system is measured, and the inspection is performed according to the standard (S23). As a result, when the inspection is passed in accordance with the standard regarding the optical performance of the objective lens system (indicated by 〇K in the figure), the adjustment of the objective lens system and, consequently, the manufacture of the objective lens system are completed (S25).

Similarly, the standard regarding the refractive index homogeneity of each optical member applied to the objective lens system of the present embodiment and the standard regarding the surface accuracy of the optical surface of each optical member are described in the imaging optical system in the observation apparatus of the present embodiment. Applied to each optical member other than the objective lens system (such as the lens of the second objective lens 11, the lenses of the relay lens system (13, 14), the reflecting prism 8, the half prism 6 and 15, etc.) It is possible to manufacture an imaging optical system and thus an observation device. Here, in each optical member other than the objective lens system of the imaging optical system, the diameter of the light beam passing therethrough is substantially smaller than in each optical member constituting the objective lens system. Therefore, for each optical member other than the objective lens system of the imaging optical system, it is also possible to apply a standard that conforms to the above-mentioned standard applied to the objective lens system, in other words, a standard that is relatively looser than the above-mentioned standard. it can.

In the present embodiment, a standard is set as a target value for the optical performance of the imaging optical system including the objective lens system. According to this standard, the longitudinal RMS value after correcting the tilt component and the power component from the wavefront aberration remaining in the imaging optical system after optical adjustment is set to 0.012 λ or less. . Further, the RMS value next to the transverse aberration component W after correcting the tilt component and the power component from the remaining wavefront aberration is set to 0.006λ or less.

Hereinafter, the validity of each standard set in the present embodiment will be verified. Table 3 below shows the relationship between the surface accuracy of each surface of each optical member constituting the objective lens system of the first embodiment and the performance of the objective lens system. Table 3 shows that the Zernike coefficient η corresponds to the η term. The surface accuracy of each surface is calculated using the expansion coefficients C1 to C3 of the first to third terms when the wavefront aberration of each surface with respect to the reference surface is expressed by Zernike polynomials. The value of 6 is shown as a coefficient on λ (= 632.8 nm). For each surface accuracy, the maximum value allowed by the fourth standard for surface accuracy is set.

Objective lens performance is the performance of the objective lens system that is expected to be calculated based on the accuracy of each surface, and the wavefront aberration remaining in the objective lens system is expressed in terms of Zelke's polynomial, as defined in Items 1 to 36. The expected values of the expansion coefficients C1 to C36 are shown by the coefficients on λ (= 632.8 ηm). The objective lens standard corresponds to the auxiliary standard for the optical performance of the objective lens system, and the expansion coefficient C1 of the first to 36th terms when the wavefront aberration remaining in the objective lens system is expressed by a Zernike polynomial The permissible value of ~ C36 is shown by the coefficient concerning λ (= 632.8 nm). Table 3

Zernike coefficient Each surface accuracy Objective lens performance Objective lens standard

1 0.0000 0.0000 0.0000

2 0.0000 0.0000 0.0000

3 0.0000 0.0000 0.0000

4 0.0000 0.0000 0.0000

5 0.0080 0.0100 0.0100

6 0.0080 0.0100 0.0100

7 0.0050 0.0079 0.0080

8 0.0050 0.0079 0.0080

9 0.0090 0.0131 0.0090

10 0.0050 0.0046 0.0080

11 0.0050 0.0046 0.0080

12 0.0050 0.0046 0.0080

13 0.0050 0.0046 0.0080

14 0.0050 0.0037 0.0080

15 0.0050 0.0037 0.0080

16 0.0050 0.0088 0.0080 17 0.0050 0.0045 0.0080

18 0.0050 0.0045 0.0080

19 0.0050 0.0044 0.0080

20 0.0050 0.0044 0.0080

21 0.0050 0.0043 0.0080

22 0.0050 0.0043 0.0080

23 0.0050 0.0042 0.0080

24 0.0050 0.0042 0.0080

25 0.0050 0.0083 0.0080

26 0.0050 0.0033 0.0080

27 0.0050 0.0033 0.0080

28 0.0050 0.0031 0.0080

29 0.0050 0.0031 0.0080

30 0.0050 0.0028 0.0080

31 0.0050 0.0028 0.0080

32 0.0050 0.0026 0.0080

33 0.0050 0.0026 0.0080

34 0.0050 0.0024 0.0080

35 0.0050 0.0024 0.0080

36 0.0050 0.0045 0.0080 Comparing the objective lens performance with the objective lens standard in Table 3, the expected value of the expansion coefficient C9 in the ninth term in the objective lens system performance estimated by calculation based on each surface accuracy However, it can be seen that the allowable value of the expansion coefficient C9 in the ninth term in the supplementary standard on the optical performance of the objective lens system is greatly exceeded. However, the component of the ninth term is a low-order spherical aberration component, and can be easily corrected by optical adjustment. Therefore, if the optical member is manufactured in accordance with the fourth standard for the surface accuracy, it is understood that the auxiliary standard for the optical performance of the objective lens system is satisfied. Table 4 below corresponds to Table 3 and verifies the validity of the first to third standards regarding the optical performance of the objective lens system. Therefore, Table 3 shows the values of each expansion coefficient, while Table 4 shows the RMS value of each wavefront aberration component included in the first to third standards related to the optical performance of the objective lens system. Is shown. In Table 4, the component indicates each wavefront aberration component included in the first to third standards regarding the optical performance of the objective lens system. For surface accuracy, the RMS value of each component of wavefront aberration of each surface with respect to the reference surface is indicated by a coefficient applied to λ (= 632.8 nm).

The objective lens performance is the performance of the objective lens system that is predicted by calculation based on the accuracy of each surface, and the expected RMS value of each component of the wavefront aberration remaining in the objective lens system is λ

(= 632.8 nm). Objective lens standard 4 corresponds to an auxiliary standard for the optical performance of the objective lens system, and shows the allowable RMS value of each component of the wavefront aberration remaining in the objective lens system by a coefficient related to λ (= 632.8 nm). I have. Objective lens standards 1 to 3 correspond to the first to third standards regarding the optical performance of the objective lens system, and the allowable RMS value of each component of the wavefront aberration remaining in the objective lens system is λ.

(= 632.8 nm). Table 4

Component Surface accuracy Objective lens performance Objective lens Objective lens Standard 4 Standard 1 to 3 All components 0.010 0.012 0.015 0.012 Rotationally symmetric component 0.005 0.007 0.006 0.007 Rotationally symmetric Second-order fourth-order residual 0.003 0.005 0.005 0.005 Non-rotational component after negative correction 0.007 0.005 0.011 0.005 Longitudinal aberration component 0.007 0.008 0.009 0.008 Longitudinal aberration higher order component 0.005 0.006 0.009 0.006 Lateral aberration component 0.006 0.004 0.008 0.005 Lateral aberration higher order component 0.005 0.004 0.008 0.004 Vs. low-order spherical aberration correction 0.009 0.010 0.013 0.010 vs. high-order aberration component 0.008 0.007 0.012 0.007 Table 4 Objective lens performance and objective lens specifications in Table 4. Comparing with 1 to 3, it can be seen that if optical members are manufactured according to the 4th standard for surface accuracy, the 1st to 3rd standards for the optical performance of the objective lens system will be satisfied. .

Table 5 below shows the relationship between the performance of the three prototype objective lens systems according to the conventional standard and the performance of the objective lens system of the first embodiment according to the present invention. In Table 5, the Zernike coefficient n indicates that it corresponds to the n-th term. For prototypes 1 to 3, the wavefront aberration remaining in the three prototype objective lens systems manufactured according to the conventional standard so that the RMS value of all components of the wavefront aberration of each surface with respect to the reference surface is 0.01 or less Is expressed by a Zernike polynomial, the values of the expansion coefficients C1 to C36 of the first to the 36th terms are represented by coefficients relating to λ (= 632.8 nm). In the embodiment, the wavefront aberration remaining in the objective lens system of the first embodiment manufactured in accordance with the standard for the refractive index homogeneity and the fourth standard for the surface accuracy is represented by the first to 36th terms when the wavefront aberration is represented by Zelke's polynomial. The values of the expansion coefficients C1 to C36 of the term are shown as coefficients related to λ (= 632.8 nm).

Zernike coefficient Prototype 1 Prototype 2 Prototype 3 Example

1 0.0004 -0.0007 0.0016 0.0001

2 -0.0006 -0.0008 -0.0015 -0.0001

3 0.0000 0.0003 -0.0001 0.0003

4 0.0012 -0.0019 0.0047 0.0002

5 -0.0032 0.0017 0.0032 0.0025

6 -0.0003 -0.0098 -0.0018 0.0067

7 0.0039 -0.0133 0.0071 0.0003 ΖΐΟΟΌ 6000 Ό 9000 "0 0200 • 0-9S

ΠΟΟ · 0 Α800 · 0-000 • 0-9200 "0- ποο · 0-2100 Ό 000 • 0-• 0-

9100 "0 2100 Ό- 6000 Ό- gooo • 0-n

1000 Ό- 刚 0 Ό- 00 "0- ΟΐΟΟ • 0-τε ειοο Ό ΖΟΟΟ · 0-0000 Ό 6100 • 0 oe

6100 Ό 1800 · 0 ζζοο Ό 2200 '0_ 6Z

8100 Ό, 0 9000 • 0 2200 • 0—% l

8000 Ό- ΗΟΟ Ό- ειοο • 0 0 • 0 11

ΖΟΟΟ 0-8S00 0-2000 • 0-Q900 '0-92 000 Ό 6920 Ό 000 0800 • 0

S200 * 0 000 0 1800 Ό 2000 • 0 u

8000 0 00 Ό- ΗΟΟ'Ο 0 • 0- u Fan 0 Ό ΙΪΟΟ · 0 SIOO • 0 刚 0 • 0 u

2100 · 0-ΙΖΟΟ Ό ζοοο • 0 0100 '0-\ l

9Ζ00 Ό- 8100 · 0-8S00 • 0 5000 • 0 oz

ΟΖΟΟ Ό ΖΟΟΟ Ό- 5S00 • 0-UQQ • 0 61 000 Ό S000 Ό οο • 0 0 • 0- 81

9S00 η ηοο · ο-6900 • 0 mo • 0 l \

6000 Ό- ΐθΐθ Ό ΟΗΟ • 0 6110 • 0 91 刚 0 "0- 8100 · 0-8Ζ00 • 0- ζπο • 0-3ΐ

8000 'Ο 9Ζ00 Ό- ^ 800 Ό- ^ ΖΟΟΌ- fl

0200 0-100 100-0 9100 * 0 A900 0- 刚 0 * 0 ZSOO 0 8 刚 0 ΖΐΟΟΌ- l \

3100 ζ ζ Fan · 0_ OOO'O- 9600 • 0 ζ εζοο'ο 0900 * 0- 9900 • 0-900 • 0-01

8910 Ό 6t0 '0- S800 • 0 6 ζεοο'ο 6' 0-Graceful • 0-ioo • 0 8

SULO / lOdt / Ud 36 0.0061 -0.0029 0.0074 0.0013 Referring to Table 5, even if the RMS value of all the components of the wavefront aberration of each surface with respect to the reference surface is 0.01 λ or less, even if it is manufactured according to the conventional standard, the objective lens It can be seen that there are cases where the supplementary standard of the present embodiment relating to the performance of the system is not satisfied. On the other hand, it can be seen that by manufacturing according to the standard regarding the refractive index homogeneity and the standard regarding the surface accuracy of the present embodiment, the auxiliary standard of the present embodiment regarding the performance of the objective lens system is satisfied.

Table 6 below is a table corresponding to Table 5, where the three prototype objective lens systems and the objective lens system of the first embodiment satisfy the first to third standards regarding performance. It is to verify that. Therefore, while Table 5 shows the values of each expansion coefficient, Table 6 shows the RMS value of each wavefront aberration component included in the first to third standards regarding the optical performance of the objective lens system. I have.

In Table 6, the component indicates each wavefront aberration component included in the first to third standards regarding the optical performance of the objective lens system. Prototypes 1 to 3 show the performance of the three prototype objective lens systems, in which the RMS value of each component of the remaining wavefront aberration is indicated by a coefficient related to λ (= 632.2.8 nm). The example is a performance of the objective lens system of the first example, and the RMS value of each component of the remaining wavefront aberration is represented by a coefficient related to λ (= 63.2.8 nm).

Ingredients Prototype 1 Prototype 2 Prototype 3 Example

All components 0.011 0.015 0.014 0.004

Rotationally symmetric component 0.006 0.013 0.012 0.002

Rotational symmetry 2nd order 4th order residual 0.006 0.009 0.010 0.001

Non-rotational component after error correction 0.009 0.007 0.006 0.003

Longitudinal aberration component 0.009 0.013 0.012 0.002

Longitudinal aberration higher order component 0.009 0.010 0.010 0.002 Lateral aberration component 0.007 0.006 0.006 0.002

Lateral aberration high order component 0.006 0.003 0.004 0.002

Error correction 0.011 0.014 0.014 0.003

And low-order spherical aberration correction 0.011 0.012 0.011 0.003

High-order aberration component 0.011 0.010 0.011 0.002 Referring to Table 6, manufacture according to the conventional standard so that the RMS values of all components of the wavefront aberration with respect to the reference surface of each surface are not more than 0.01 λ. Also, it can be seen that the first to third standards of the present embodiment regarding the performance of the objective lens system are not satisfied. On the other hand, by manufacturing according to the standard regarding the refractive index homogeneity and the standard regarding the surface accuracy of the present embodiment, the first to third standards of the present embodiment regarding the performance of the objective lens system must be satisfied. I understand.

Table 7 below shows the fourth standard for the surface accuracy of the present embodiment, and the conventional singular surface that causes the RMS value of all the components of the wavefront aberration to be less than 0.01 λ but causes performance degradation. The relationship is shown. In Table 7, it is shown that the Zernike coefficient η corresponds to the η term. The surface accuracy standard corresponds to the fourth standard relating to the surface accuracy of the present embodiment, and the allowable values of the expansion coefficients C1 to C36 of the first to the 36th terms when the wavefront aberration is represented by Zernike polynomials λ (= 632.8 nm). The actual polished surface corresponds to the surface actually polished according to the conventional technology so that the RMS value of all the components of the wavefront aberration is equal to or less than 0.1 λ λ, and when the wavefront aberration is expressed by Zernike polynomial The values of the expansion coefficients C1 to C36 in the first to the 36th terms are indicated by coefficients relating to λ (= 632.8 nm). The 30 surface corresponds to the surface where the RMS value of all the components of the wavefront aberration is less than 0.01 λ but only the 10th term of the Zernike polynomial is large, and the wavefront aberration is expressed by the Zernike polynomial The values of the expansion coefficients C1 to C36 in the first to 36th terms are shown by the coefficients related to λ (= 632.8 nm). On the 30th higher-order coma composite surface, the RMS value of all components of the wavefront aberration is less than 0.01 λ, but the 10th and 14th terms of the Zernike polynomials are generated by almost the same amount. Corresponding, the first term when its wavefront aberration is expressed by Zernike polynomial To the 36th term, the value of the expansion coefficient C 36 is indicated by the coefficient of ぇ (= 632.8 nm). Table 7

Zernike coefficient Surface accuracy standard Actually polished surface 30 surfaces 3 Θ Higher order

Top composite surface

1 0.0000 0.0000 0.0000 0.0000

2 0.0000 0.0000 0.0000 0.0000

3 0. 0000 0. 0000 0. 0000 0.0000

4 0.0000 0.0000 0.0000 0.0000

5 0.0080 0.0013 0.0000 0.0000

6 0.0080 0.0060 0.0000 0.0000

7 0.0050 0.0001 0.0000 0.0000

8 0.0050-0.0002 0.0000 0.0000

9 0.0090 0.0040 0.0000 0.0000

10 0.0050 -0.0018 0.0284 0.0199

11 0.0050 -0. 0004 0.0000 0.0000

12 0.0050 0.0041 0.0000 0.0000

13 0.0050 0.0008 0.0000 0.0000

14 0.0050 0.0011 0.0000 0.0242

15 0.0050 0.0007 0.0000 0.0000

16 0.0050 -0.0180 0.0000 0.0000

17 0.0050 0.0032 0.0000 0.0000

18 0.0050 0.0057 0.0000 0.0000

19 0.0050-0.0001 0.0000 0.0000

20 0.0050 -0.0007 0.0000 0.0000

21 0.0050 0.0048 0.0000 0.0000

22 0.0050 -0.0029 0.0000 0.0000 23 0.0050 0.0012 0.0000 0.0000

24 0.0050 0.0077 0.0000 0.0000

25 0.0050 0.0110 0.0000 0.0000

26 0.0050 -0.0009 0.0000 0.0000

27 0.0050 -0.0005 0.0000 0.0000

28 0.0050 -0.0036 0.0000 0.0000

29 0.0050 -0.0019 0.0000 0.0000

30 0.0050 0.0002 0.0000 0.0000

31 0.0050 -0.0015 0.0000 0.0000

32 0.0050 0.0014 0.0000 0.0000

33 0.0050 0.0022 0.0000 0.0000

34 0.0050 -0.0209 0.0000 0.0000

35 0.0050 0.0018 0.0000 0.0000

36 0.0050 -0.0030 0.0000 0.0000 FIG. 17 shows the wavefront aberration corresponding to the actual polished surface shown in Table 7 in a contour diagram of 0.005λ. FIG. 18 is an exaggerated three-dimensional view of the undulation of the actual polished surface in Table 7. FIG. 19 shows the wavefront aberration corresponding to surface 30 in Table 7 in a contour diagram of 0.005λ. FIG. 20 is an exaggerated three-dimensional view of the swell of 30 surfaces in Table 7. FIG. 21 shows the wavefront aberration corresponding to the 30th higher-order coma composite surface in Table 7 as a contour map of 0.005λ. FIG. 22 is an exaggerated three-dimensional view of the undulation of the 30th higher-order coma composite surface in Table 7.

The following Table 8 is a table corresponding to Table 7, and shows a relationship between the first to third standards relating to the surface accuracy of the present embodiment and the surface accuracy of the conventional singular surface. Therefore, Table 7 shows the values of each expansion coefficient, while Table 8 shows the RMS value of each wavefront aberration component included in the first to third standards for surface accuracy. . In Table 8, the components indicate the wavefront difference components included in the first to third standards for the surface accuracy. Surface accuracy standards are the first to third standards for surface accuracy. The RMS value of each component is shown as a coefficient on λ (= 632.8 nm). For the actual polished surface, the RMS value of each component of the wavefront aberration corresponding to the actual polished surface in Table 7 is indicated by a coefficient applied to λ (= 632.8 nm). On the 30th surface, the RMS value of each component of the wavefront aberration corresponding to the 30th surface in Table 7 is indicated by a coefficient applied to λ (= 632.8 nm). 3 Θ Higher-order coma composite surface shows the RMS value of each component of wavefront aberration corresponding to the 30th higher-order coma composite surface in Table 7 as a coefficient related to λ (= 632.8 nm). Table 8

Component Surface accuracy standard Actually polished surface 30 surfaces 30 higher order

Coma composite plane All components 0.0100 0.0103 0.0100 0.0099 Rotationally symmetric component 0.0050 0.0080 0.0000 0.0000 Rotationally symmetric 4th order residual 0.0030 0.0078 0.0000 0.0000 Non-rotational component after ass correction 0.0050 0.0050 0.0100 0.0099 Longitudinal aberration component 0.0070 0.0086 0.0000 0.0000 Longitudinal aberration high order Component 0.0050 0.0084 0.0000 0.0000 Lateral aberration component 0.0050 0.0052 0.0100 0.0099 Higher transverse aberration component 0.0030 0.0052 0.0100 0.0099 First correction 0.0080 0.0100 0.0100 0.0099 First and lower order spherical aberration correction 0.0050 0.0098 0.0100 0.0099 Higher order aberration component 0.0030 0.0098 0.0100 0.0099 8th Referring to the table, the RMS values of all the components of the wavefront aberration are suppressed to 0.01 λ or less in the conventional singular surface, but each of the other standards included in the first to third standards for surface accuracy It can be seen that the value exceeds the allowable value of the component.

Table 9 below shows the effect of one singular surface in Table 7 on the wavefront aberration of the objective lens system. In Table 9, the components are the first criteria for the performance of the objective lens system. Each wavefront aberration component included in the first to third standards is shown. The objective lens standards correspond to the first to third standards regarding the optical performance of the objective lens system, and the RMS value of each component of the wavefront aberration remaining in the objective lens system is set to λ (= 632.8 nm). The coefficient is shown as Here, since the surface where the singular surface is generated is not specified in the objective lens, the generated surface is shown as a non-bonded surface with a refractive index of 1.7 (average value). I have.

For the actual polished surface, the RMS value of each component of the wavefront difference remaining in the objective lens system containing one actual polished surface in Table 7 is shown by the coefficient applied to λ (= 632.8 nm). For the three surfaces, the RMS value of each component of the wavefront aberration remaining in the objective lens system including one 3Θ surface in Table 7 is indicated by a coefficient applied to λ (= 632.8 nm). For the 30th higher-order coma composite surface, the RMS value of each component of the wavefront difference remaining in the objective lens system containing one 3 3 higher-order coma composite surface in Table 7 is applied to λ (= 632.8 nm). It is shown by a coefficient.

9

Coma composite plane All components 0.0120 0.0103 0.0070 0.0070 Rotationally symmetric component 0.0070 0.0056 0.0000 0.0000 Rotationally symmetric 4th order residual 0.0050 0.0054 0.0000 0.0000 Non-rotational component after ass correction 0.0050 0.0042 0.0070 0.0070 Longitudinal aberration component 0.0080 0.0060 0.0000 0.0000 Longitudinal aberration higher order component 0.0060 0.0059 0.0000 0.0000 Lateral aberration component 0.0050 0.0036 0.0070 0.0070 Lateral aberration higher order component 0.0040 0.0036 0.0070 0.0070 Absolute correction 0.0100 0.0070 0.0070 0.0070 Absolute and low Second order spherical aberration correction 0.0080 0.006 0.0070 0.0070 Higher order aberration component 0.0070 0.006 0.0070 0.0070 Referring to Table 9, the objective lens system that actually contains one polished surface exceeds the allowable value of the rotationally symmetric second- and fourth-order residual components of the first standard. The objective lens system including one lens exceeds the allowable value of the non-rotational component after the first correction of the first standard. In addition, the objective lens system that actually contains one polished surface is below the permissible values of all the components of the second standard, but the objective lens system that contains one 30-plane or 30 higher-order coma composite surface has the second tolerance. It exceeds the allowable value of the standard lateral aberration component and the allowable value of the higher order lateral aberration component. For the third standard, the values are lower than the allowable values for all components. In any case, it can be seen that the performance of the objective lens system is greatly deteriorated only by including one singular surface.

Table 10 below shows the relationship between the first to third standards for surface accuracy and the fourth standard for surface accuracy. In Table 10, the component indicates each wavefront aberration component included in the first to third standards for the surface accuracy. The surface accuracy standard shows the RMS value of each component in the 1st to 3rd standards related to surface accuracy as a coefficient on λ (= 632.8 nm). In the Zernike standard, the RMS value of each component converted from the fourth standard for surface accuracy is expressed as a coefficient related to λ (= 632.8 nm). Table 10

Component Surface accuracy standard Zernike standard

All components 0.0100 0.0100

Rotationally symmetric component 0.0050 0.0050

Rotationally symmetric second-order fourth-order residual 0.0030 0.0029

Non-rotational component after error correction 0.0050 0.0073

Longitudinal aberration component 0.0070 0.0067

Longitudinal aberration higher order component 0.0050 0.0053

Lateral aberration component 0.0050 0.0058

Lateral aberration higher order component 0.0030 0.0052

Error correction 0.0080 0.0089 And low-order spherical aberration correction 0.0005

Higher-order aberration component 0.0030 0.0075 Referring to Table 10, a good correspondence is recognized between the first to third standards and the fourth standard regarding surface accuracy. It can be seen that the standards 1 to 3 are set more strictly in terms of accuracy than the fourth standard. Therefore, in the above description, the objective lens system according to the fourth standard for surface accuracy is taken as an example, but the objective system according to a standard arbitrarily selected from the first to third standards for surface accuracy is taken as an example. The lens system can also satisfy a desired performance standard. That is, in the present embodiment, the optical member of the objective lens system is manufactured and assembled according to the standard regarding the refractive index homogeneity and the standard arbitrarily selected from the first to fourth standards regarding the surface accuracy. By performing necessary optical adjustments in the objective lens system specified, the objective lens system satisfies the standards arbitrarily selected from the first to third standards and the auxiliary standard for the objective lens system performance Can be satisfied. Furthermore, by manufacturing optical members other than the objective lens system of the imaging optical system in accordance with the standard corresponding to the optical members of the objective lens system, and performing necessary optical adjustments in the assembled imaging optical system, It can meet the standards regarding the performance of the imaging optical system.

Actually, when the polishing was performed according to the first standard for surface accuracy, it was found that the polishing satisfies the fourth standard (Zernike standard) for surface accuracy. Therefore, it was found that a surface processed with desired accuracy can be obtained by polishing with the first standard relating to surface accuracy. Similarly, it was confirmed that even if polishing was performed according to the second or third standard for surface accuracy, the fourth standard (Zernike standard) for surface accuracy was satisfied.

In addition, as described above, a single singular surface may generate a wavefront aberration that occupies most of the standard value related to the performance of the objective lens system. Table 7 shows the Zernike data for this type of singular surface, and Table 8 shows the RMS values for each component. This kind of singular surface has a special shape with a large deviation from a true sphere, as shown in FIGS. 18, 20 and 22. Table 9 shows that this kind of It shows how a single singular surface in the objective lens system affects the transmitted wavefront aberration of the objective lens system.

In an actual polished surface example, the presence of one singular surface causes an aberration of 80% or more of the standard value for the performance of the objective lens system. Therefore, if even one such polished surface is generated, it is highly likely that the standard for the performance of the objective lens system cannot be finally satisfied. In addition, with respect to unique surfaces such as the 30th surface and the 30th higher-order coma composite surface, only one surface generates aberration exceeding the standard value for the performance of the objective lens system. A singular surface with such a tendency may actually occur, and in such a case, it is considered that an objective lens system that does not satisfy the performance standards will be manufactured. The FIA-based alignment device shown in FIG. 1 measures the position of the alignment mark (wafer mark WM) in the X direction (0 degree direction) and the Y direction (90 degree direction). In such an alignment apparatus, it is possible to separately measure the position in each direction by using two imaging devices, such as the CCD for the X direction and the CCD for the Y direction. In this case, it becomes easy to independently adjust the light receiving surface of the CCD for the X direction and the light receiving surface of the CCD for the Y direction to the X direction focus position and the Y direction focus position. Therefore, as long as the specifications of the present invention are satisfied, astigmatism (as) can be corrected by optical adjustment.

In the case of a relatively small objective lens system such as an objective lens system included in a microscope, each lens is inserted into the lens chamber with the eccentricity being driven, and each lens chamber into which the lens is inserted is mirrored. Manufactured by being incorporated in a cylinder. In this case, the components generated by the mechanical presser mechanism are generally in the order of the coefficients, such as the Zernike coefficient tilt components C2 and C3, the focus component C4, and the positive component C5 and C6. It is thought that they are lined up from the larger one. If the tilt component is within the tolerance, it is already folded and there is no problem. The focus component, the positive component, the coma aberration component, and the spherical aberration component can be corrected by adjusting the distance between the optical members and the eccentricity. In addition, the gas component can be corrected by an adjustment mechanism using a cylindrical surface. Therefore, the aberration components that need to be considered by the mechanical mechanism are the 30 components of Cernike coefficients C10 and C11, the higher order components of C12 and C13, and the C14 and C14 components. And higher-order coma components of C15. It is necessary to pay close attention to the generation of these aberration components when assembling them into the lens chamber. However, the generation of these aberration components is ignored in objective lens systems with relatively small diameters (for example, effective diameters of 50 mm or less). It can be kept as small as possible and can be neglected if a smaller mechanism is adopted as needed.

Basically, if the fourth standard for surface accuracy (Zernike standard) is satisfied, the objective lens system performance predicted by calculation based on each surface accuracy satisfies the auxiliary standard of the present embodiment. It is on the street. At this time, in the calculation based on the accuracy of each surface, the cancellation effect of the non-rotationally symmetric component when the lens is incorporated is estimated to be about 0.5. Hereinafter, the offset effect will be described. If the number of lenses used in the optical system is large, the non-rotationally symmetric component of the Zernike generated in each lens is offset to some extent by the rotation adjustment of each lens in the plane perpendicular to the optical axis. For example, if a non-rotationally symmetric component having a peak value in the 0 degree direction remains in one lens and a similar non-rotationally symmetric component in the 0 degree direction remains in another lens, one of the lenses is By rotating in the plane perpendicular to the optical axis, wavefront aberration can be reduced. Here, such an effect is called an offset effect and is expected to be about 0.5.

The relationship between the amount of each component included in the standard and the amount of low-order aberration or high-order aberration does not correspond one-to-one. However, no matter which of the four standards for surface accuracy is adopted, it must be set so as to satisfy the standard for the performance of the final objective lens system. By setting a standard for surface accuracy in this way, the generation of waviness components on the polished surface is actually reduced. If the standard regarding the surface accuracy is not set, the above-mentioned singular surface is generated, and the standard regarding the performance of the objective lens system and eventually the standard regarding the performance of the imaging optical system cannot be satisfied.

The method for estimating the transmitted wavefront aberration of the objective lens system from the Zernike coefficients of each surface is shown below. The Zernike coefficients are standardized for the effective diameter of each lens. Therefore, it is necessary to convert to the beam diameter actually used. Since the surface has already been fitted with the Zellnike function, the radius is reduced at the center of the optical axis and Finding the perfect Zernike coefficient is a radius! It is easily possible by calculating 0 and converting it by the ratio of luminous flux diameter / effective diameter.

The inspection of the surface accuracy by the interferometer is performed by measuring the reflected wavefront aberration as shown in FIG. Therefore, to convert to transmitted wavefront aberration, the difference between the glass refractive index n at the measurement wavelength and the air refractive index or the adhesive refractive index in the case of a cemented lens (in each case, represented by ηθ) ( n— η θ). If the measured wavelength (normally He—Ne wavelength: λ = 63.2.8 nm) is different from the used wavelength λ 0 at the time of conversion, λ 0 Ζ λ to convert the wavelength, which is the unit of wavefront aberration. Need to be multiplied. The value obtained by calculating the transmitted wavefront aberration of the objective lens system of the first example by such a method is shown in the column of objective lens performance in Table 3. As described above, this estimation result is almost consistent with the standard regarding the performance of the objective lens system. Therefore, if each surface is polished according to the standard of the present embodiment, an objective lens system satisfying a desired standard regarding performance can be obtained.

Further, in this embodiment, the Ρ-V value (peak to valley: difference between maximum and minimum) of the wavefront aberration due to the refractive index distribution of each optical member is suppressed to 0.05 λ or less. From the results of the investigation, it was found that it is possible to supply an optical material that satisfies such accuracy regarding refractive index homogeneity for optical members with a relatively small diameter (for example, an effective diameter of 60 mm or less). . The refractive index distribution of the optical member shows a gentle distribution shape, and there is little local undulation.

Therefore, when this P-V value is subjected to component analysis, at most the higher-order undulation component is less than 0.001 λ in P-V value, and it is considered that there is no substantial effect. As disclosed in Japanese Patent Application Laid-Open No. 8-55505, an aberration component generated due to a low-order refractive index distribution is a component that can be corrected by adjusting the optical system, and is represented by a Zernike coefficient. Then, it corresponds to the expansion coefficient C2 in the second term to the expansion coefficient C9 in the ninth term. Therefore, it is considered that if the standard for the refractive index homogeneity of the present embodiment is satisfied, there is no substantial adverse effect on the performance of the final objective lens system.

Of the standards relating to surface accuracy and the standards relating to performance, the second standard is the most effective because it conforms to the standard for the performance of the final imaging optical system. However, usually In commercial interferometers, numerical values for such components have no function in software and are not displayed, so they must be calculated from Zernike coefficients. In an actual FIA-based alignment device, longitudinal aberration contributes to variations in the focus position when detecting the positions of various marks, and lateral aberration causes a measurement error in the horizontal direction when detecting the positions of various marks. Although the technology for reducing these error factors in image processing of alignment marks in accordance with the software processing technology has made remarkable progress, the performance of the imaging optical system as hardware is generally high. Is more desirable. For example, if no aberration occurs ideally, there is no error factor in the imaging optical system including the objective lens system, and only the influence of the shape error of the alignment mark formed on the wafer remains.

The exposure apparatus according to the present embodiment is electrically, mechanically, or optically connected to each optical member, each stage, and the like in the present embodiment shown in FIG. 1 so as to achieve the functions described above. Can be assembled. Then, the mask is illuminated by the illumination system IL (illumination step), and the transfer pattern formed on the mask is projected onto the photosensitive substrate using the projection optical system PL including the projection optical modules PM1 to PM5. By performing scanning exposure (exposure step), a micro device (semiconductor element, liquid crystal display element, thin film magnetic head, etc.) can be manufactured. Hereinafter, an example of a method for obtaining a semiconductor device as a micro device by forming a predetermined circuit pattern on a wafer or the like as a photosensitive substrate using the exposure apparatus of the present embodiment shown in FIG. This will be described with reference to the flowchart of FIG.

First, in step 301 of FIG. 23, a metal film is deposited on one lot of wafers. In the next step 302, a photoresist is applied on the metal film on the wafer of the lot. Then, in step 303, using the exposure apparatus shown in FIG. 1, the image of the pattern on the mask is transmitted through the projection optical system (projection optical module) to each shot on the wafer of the lot. It is sequentially exposed and transferred to the area. Thereafter, in step 304, the photoresist on the one lot of wafers is developed, and then in step 300, etching is performed on the one lot of wafers using the resist pattern as a mask. Putter on the mask A circuit pattern corresponding to the pattern is formed in each shot area on each wafer. Thereafter, a device such as a semiconductor element is manufactured by forming a circuit pattern of an upper layer and the like. According to the above-described semiconductor device manufacturing method, a semiconductor device having an extremely fine circuit pattern can be obtained with good throughput. In the exposure apparatus shown in FIG. 1, by forming a predetermined pattern (circuit pattern, electrode pattern, etc.) on a plate (glass substrate), a liquid crystal display element as a microdepth can be obtained. . Hereinafter, an example of the technique at this time will be described with reference to the flowchart of FIG. In FIG. 24, in a pattern forming step 401, a so-called optical lithography method in which a mask pattern is transferred and exposed to a photosensitive substrate (eg, a glass substrate coated with a resist) using the exposure apparatus of the present embodiment. One step is performed. By this photolithography process, a predetermined pattern including a large number of electrodes and the like is formed on the photosensitive substrate. Thereafter, the exposed substrate is subjected to a developing process, an etching process, a reticle peeling process, etc., to form a predetermined pattern on the substrate, and the process proceeds to the next color filter forming process 402. .

Next, in the color filter forming step 402, a large number of sets of three dots corresponding to R (Red), G (Green), and B (Blue) are arranged in a matrix, or R, G, A color filter is formed by arranging a plurality of sets of three stripe filters B in the horizontal scanning line direction. Then, after the color filter forming step 402, a cell assembling step 403 is performed. In the cell assembling step 403, a liquid crystal panel (liquid crystal) is used by using the substrate having the predetermined pattern obtained in the pattern forming step 401, the color filter obtained in the color filter forming step 402, and the like. Assemble the cell). In the cell assembling step 403, for example, a liquid crystal is interposed between the substrate having the predetermined pattern obtained in the pattern forming step 401 and the color filter obtained in the color filter forming step 402. Inject to manufacture liquid crystal panels (liquid crystal cells).

Then, in the module assembling step 404, each component such as an electric circuit and a pack light for performing the display operation of the assembled liquid crystal panel (liquid crystal cell) is attached. Completed as a liquid crystal display element. According to the above-described method for manufacturing a liquid crystal display element, a liquid crystal display element having an extremely fine circuit pattern can be obtained with high throughput.

In the above-described embodiment, the wavefront aberration is represented by a Zernike polynomial, but without using a Zernike polynomial as disclosed in Japanese Patent Application Laid-Open No. H11-125125, for example. Wavefront aberration can also be expressed.

Further, in the above-described embodiment, when the wavefront aberration is expressed by the Zernike polynomial, the expansion is performed up to the 36th term. it can. In this case, for paragraphs 37 onwards, for example, the standard values for paragraph 36 can be applied.

Further, in the above embodiment, the present invention is applied to the FIA-based alignment device for detecting the position of the wafer mark. However, the present invention is not limited to this. Japanese Patent Application Laid-Open No. 7-71,918, Japanese Patent Application Laid-Open No.

1 2 8 8 14 JP, JP-A-10- 1 2 280 0 JP, and JP 2000-

The present invention can be applied to an overlay accuracy measuring device and an inter-pattern dimension measuring device disclosed in, for example, US Pat.

As described above, the present invention can take various configurations without being limited to the above-described embodiment. Industrial applicability

As described above, according to the present invention, an objective lens system capable of favorably suppressing the remaining higher order wavefront aberration components can be realized at a design level. Further, in the present invention, by designing the objective lens system by suppressing at least one of a higher order component of wavefront aberration generated by optical adjustment of the objective lens system and a difference of eccentric coma aberration for each wavelength, the remaining higher order Components can be suppressed well. Furthermore, in the present invention, the wavefront aberration due to the refractive index distribution of each optical member constituting the objective lens system is suppressed, and the wavefront aberration of each surface of each optical member with respect to the reference plane is suppressed, and each optical member is By manufacturing the same, high-order wavefront aberration components remaining in the objective lens system can be favorably suppressed. Therefore, in the observation apparatus for observing an object image formed via the imaging optical system including the objective lens system of the present invention, the objective lens system and, consequently, the higher order components of the wavefront aberration remaining in the imaging optical system are excellent. Can be suppressed. Further, in the exposure apparatus provided with the observation device of the present invention, for example, the mask and the photosensitive substrate can be positioned with high accuracy with respect to the projection optical system using the observation device, and good exposure can be performed. Further, in the microdevice manufacturing method using the exposure apparatus of the present invention, a good microdevice can be manufactured through a good exposure process.

Claims

The scope of the claims

1. In order from the object side, a first lens group having a positive refractive power and a second lens group having a negative refractive power are provided.

The center thickness of the lens closest to the object side in the first lens group is d1, and the thickness of the lens closest to the object side along the optical axis between the object side surface and the object is d1. When the air conversion distance is d 0,

d 1 / d 0 <0.2

An objective lens system satisfying the following conditions:

2. The Abbe number of the object-side lens of the pair of lenses disposed closest to the image in the second lens group is set to 1, and the Abbe number of the image-side lens of the pair of lenses is set to 1. When 2

I Li 1 Li 2 I Ku 15

V 1 <40

V 2 <40

2. The objective lens system according to claim 1, wherein the following condition is satisfied.

3. The objective lens system according to claim 2, wherein the pair of lenses constitute a cemented lens.

4. Let D be the center thickness of the lens component having the largest negative refractive power among the lens components in the objective lens system, and select the image-side surface of the lens closest to the image side in the second lens group. When the distance along the optical axis from the object is L,

DZL K 0.17

4. The objective lens system according to claim 1, wherein the objective lens system satisfies the following condition.

5. In the manufacturing method of the objective lens system,

An optical adjustment of the objective lens system to correct aberrations remaining in the assembled objective lens system.

6. In the design step, when the numerical aperture on the object side of the objective lens system is NA and the center wavelength of the light used is λ1, the center thickness of each lens constituting the objective lens system and the air of each lens The MS (root mean square) value of the higher order spherical aberration component of the wavefront aberration generated when the distance is changed by d (mm) is (30 · d · NA ⁶ ) · λ 6. The method for manufacturing an objective lens system according to claim 5, wherein the value is set to 1 or less.

7. In the design step, when the numerical aperture on the object side of the objective lens system is Ν and the center wavelength of the light used is λ1, each lens constituting the objective lens system is oriented in a direction orthogonal to the optical axis. The RMS value of the higher-order coma aberration component among the wavefront aberrations generated when decentered by s (mm) along the axis is set to (50 · s · NA ⁵ ) · λ1 or less. 7. The method for producing an objective lens system according to item 5 or 6.

8. In the design step, when the numerical aperture on the object side of the objective lens system is ΝΑ and the center wavelength of the light used is λ1, each lens constituting the objective lens system is moved in a direction orthogonal to the optical axis. The absolute difference between the RMS value of the decentered coma component of the shortest wavelength of the used light and the RMS value of the decentered coma aberration component of the longest wavelength of the used light among the wavefront aberrations generated when decentering by s (mm) along 8. The method for manufacturing an objective lens system according to claim 5, wherein the value is set to be equal to or less than (50 · s · NA ³ ) · λ1.

9. In the manufacturing method of the objective lens system,

10. In the manufacturing process, when the wavelength of the wavefront aberration measurement light is λ, the Ρ-V value (peak to valley: maximum-minimum difference) of the wavefront aberration due to the refractive index distribution of each optical member is defined as 0. 10. The method for manufacturing an objective lens system according to claim 9, wherein the objective lens system is controlled to be not more than 005λ.

11. In the manufacturing process, when the wavelength of the wavefront aberration measuring light is represented by, the RMS values of all components after correcting the tilt component and the power component from the wavefront aberration of each surface of each of the optical members with respect to the reference surface are calculated. The rotationally symmetric component of all the components is suppressed to 0.005 λ or less, and the RMS value of all the components is suppressed to 0.005 λ or less. The RMS value of the residual is suppressed to 0.003 λ or less, and the RMS value of the non-rotationally symmetric component after correcting the negative component from all the components is suppressed to 0.005 λ or less. Or the method for manufacturing an objective lens system according to item 10.

12. In the manufacturing process, when the wavelength of the wavefront aberration measuring light is λ, the RMS values of all components after correcting the tilt component and the power component from the wavefront aberration of each surface of each optical member with respect to the reference surface. And the RMS value of the longitudinal aberration component of all the components is suppressed to 0.007 λ or less, and the RMS value of the longitudinal aberration higher-order component of all the components Is suppressed to 0.005λ or less, the RMS value of the transverse aberration component of all the components is suppressed to 0.005λ or less, and the RMS value of the high-order transverse aberration component of all the components is suppressed to 0.003λ or less. 11. The method for manufacturing an objective lens system according to claim 9 or 10, wherein:

13. In the manufacturing process, when the wavelength of the wavefront aberration measurement light is λ, the RMS values of all components after correcting the tilt component and the power component from the wavefront aberration of each surface of each optical member with respect to the reference surface Was suppressed to 0.010 λ or less, and the RMS value of the component after correcting the vas component from all the components was suppressed to 0.008 λ or less, and the vas component and low-order spherical aberration component were corrected from the all components. The objective according to claim 9 or 10, wherein the MS value of the subsequent component is suppressed to 0.005 λ or less, and the RMS value of the high-order aberration component of all the components is suppressed to 0.003 λ or less. Manufacturing method of lens system.

14. In the above manufacturing process, when the wavelength of the wavefront aberration measurement light is λ, the RMS values of all components after correcting the tilt component and the power component from the wavefront aberration of each surface of each of the optical members with respect to the reference surface. When the wavefront aberration is represented by a Zernike polynomial, the expansion coefficient C 9 in the ninth term is suppressed to 0.009 λ or less, and the expansion coefficient in the 10 th to 36 th terms 11. The method for manufacturing an objective lens system according to claim 9, wherein C10 to C36 are each suppressed to 0.005λ or less.

15. Prior to the manufacturing process, the designing process of designing the objective lens system by suppressing at least one of a higher order component of wavefront aberration and a difference in eccentric coma aberration for each wavelength generated by optical adjustment of the objective lens system. The method for manufacturing an objective lens system according to any one of claims 9 to 14, wherein the method comprises:

16. In the design process, when the numerical aperture on the object side of the objective lens system is ΝΑ and the center wavelength of the light used is λ1, the center thickness of each lens constituting the objective lens system and the The RMS value of the higher-order spherical aberration component among the wavefront aberrations generated when the air spacing is changed by d (mm) is (30 · d · NA ⁶ ) · λ1 or less. 16. The method for manufacturing an objective lens system according to claim 15, wherein the method is set as follows.

17. In the design step, when the numerical aperture on the object side of the objective lens system is NA and the center wavelength of the light used is λ1, each lens constituting the objective lens system is oriented in a direction orthogonal to the optical axis. The RMS value of the high-order coma aberration component among the wavefront aberrations generated when decentering by s (mm) along is set to (50 · s · NA ⁵ ) · λ1 or less. 17. The method for manufacturing an objective lens system according to claim 15 or 16.

18. In the design step, when the numerical aperture on the object side of the objective lens system is ΝΑ and the center wavelength of the light used is λ1, each lens constituting the objective lens system is oriented in a direction orthogonal to the optical axis. Of the wavefront aberration generated when the beam is decentered by s (mm) along the distance between the RMS value of the decentered coma component of the shortest wavelength of the used light and the RMS value of the decentered coma component of the longest wavelength of the used light objective lens system method according to any one of claims 15 to 17, the absolute value and said ^{(50 * s 'NA 3)} ' be set to a 1 the following differences.

19. In order to suppress the wavefront aberration remaining in the objective lens system after the optical adjustment, the wavefront aberration due to the refractive index distribution of each optical member constituting the objective lens system is suppressed, and each surface of each optical member is An objective lens system characterized in that wavefront aberration with respect to a reference plane is suppressed.

20. When the wavelength of the wavefront aberration measuring light is λ, the RMS values of all components after correcting the tilt component and the power component from the remaining wavefront aberration are suppressed to 0.012λ or less, and the total components are The RMS value of the rotationally symmetric component is suppressed to 0.007 λ or less, and the RMS value of the rotationally symmetric component obtained by removing the quadratic and quartic curve components from the rotationally symmetric component is 0.005 λ or less. 20.The objective lens according to claim 19, wherein the RMS value of the non-rotationally symmetric component after correcting the negative component from all the components is suppressed to 0.005 λ or less. system.

21. Assuming that the wavelength of the wavefront aberration measuring light is λ, the RMS values of all components after correcting the tilt component and the power component from the remaining wavefront aberration are suppressed to 0.012λ or less, and The RMS value of the longitudinal aberration component is suppressed to 0.008 λ or less, the RMS value of the longitudinal higher order component of all the components is suppressed to 0.006 λ or less, and the RMS value of the transverse aberration component of all the components is 20. The objective lens system according to claim 19, wherein the objective lens system is controlled to 0.005 λ or less, and the RMS value of the high-order lateral difference component of all components is suppressed to 0.004 λ or less.

22. When the wavelength of the wavefront aberration measurement light is λ, the RMS values of all components after correcting the tilt component and the power component from the remaining wavefront aberration are suppressed to 0.012 λ or less, and the total components are The RMS value of the component after the correction of the ass component is suppressed to 0.010 λ or less, and the RMS value of the component after the correction of the aus component and the low-order spherical aberration component from all the components is 0.1. 20. The objective lens system according to claim 19, wherein the RMS value of the high-order aberration component of all the components is suppressed to 0.007 λ or less.

23. When the wavefront aberration is represented by a Zernike polynomial, the expansion coefficient C 9 of the ninth term is suppressed to 0.009λ or less, and the expansion coefficient C 10 to C 36 of the tenth to 36th terms is 0.008. The objective lens system according to any one of claims 20 to 22, wherein each of the objective lens systems is suppressed to λ or less.

24. An imaging optical system comprising the objective lens system according to any one of claims 1 to 4 or the imaging optical system including the objective lens system according to any one of claims 19 to 23. An observation apparatus for observing an object image formed through a system.

25. An observation apparatus which includes an imaging optical system including an objective lens system and observes an object image formed through the imaging optical system, In order to suppress the wavefront aberration remaining in the imaging optical system after the optical adjustment, the wavefront aberration due to the refractive index distribution of each optical member other than the objective lens system in the imaging optical system is suppressed, and An observation apparatus, wherein wavefront aberration of each surface of the optical member with respect to a reference surface is suppressed.

26. An observation apparatus which includes an imaging optical system including an objective lens system and observes an object image formed through the imaging optical system.

In order to suppress the wavefront aberration remaining in the imaging optical system after the optical adjustment, the refractive index of each optical member among all the optical members arranged in the optical path between the objective lens system and the object image An observation apparatus wherein wavefront aberration due to distribution is suppressed, and wavefront aberration of each surface of each optical member with respect to a reference surface is suppressed.

27. Assuming that the wavelength of the wavefront aberration measurement light is λ, the RMS value of the longitudinal aberration component after correcting the tilt component and the power component from the remaining wavefront aberration is suppressed to 0.012λ or less. The RMS value of the transverse aberration component after correcting the tilt component and the power component from the remaining wavefront aberration is suppressed to 0.006λ or less. 7. The observation device according to 6.

28. The method according to any one of claims 25 to 27, wherein the 波 -V value of the wavefront aberration due to the refractive index distribution of each optical member is suppressed to 0.005λ or less. 2. The observation device according to 1.

29. The RMS value of all components after correcting the tilt component and the power component from the wavefront aberration of each surface of each optical member with respect to the reference surface is suppressed to 0.010λ or less, and the rotation of all the components described above is performed. The RMS value of the symmetric component is suppressed to 0.005λ or less, and the RMS value of the rotational symmetric component obtained by removing the quadratic-quadratic curve component from the rotational symmetric component is the RMS value of the quadratic residual.

Wherein the RMS value of the non-rotational symmetric component after correcting the negative component from all the components is suppressed to 0.005 λ or less. 28. The observation device according to any one of 27.

30. The RMS value of all components after correcting the tilt component and the power component from the wavefront aberration of each surface of each optical member with respect to the reference surface is suppressed to 0.010 λ or less, and the longitudinal aberration components of all the components The RMS value is suppressed to 0.0007 λ or less, the RMS value of the longitudinal aberration higher-order component of all components is suppressed to 0.005 λ or less, and the RMS value of the transverse aberration component of all components is 0.005 λ or less. 28. The observation apparatus according to claim 25, wherein the third order value of the high order transverse aberration component of all the components is suppressed to 0.003 or less.

31. The RMS value of all components after correcting the tilt component and the power component from the wavefront aberration of each surface of each optical member with respect to the reference surface is suppressed to 0.010 λ or less. The RMS value of the component after the correction is suppressed to 0.008 λ or less, and the RMS value of the component after the ass component and the low-order spherical aberration component are corrected from all the components is suppressed to 0.005 λ or less. The observation apparatus according to any one of claims 25 to 27, wherein RMS values of high-order aberration components of all the components are suppressed to 0.003λ or less.

32. The RMS value of all components after correcting the tilt component and the power component from the wavefront aberration of each surface of each optical member with respect to the reference surface is suppressed to 0.010 λ or less, and the wavefront aberration is expressed by Zelke polynomial. When expressed, the expansion coefficient C 9 of the ninth term is suppressed to 0.0009λ or less, and the expansion coefficients C 10 to C 36 of the 10th to 36th terms are suppressed to 0.005λ or less, respectively. The observation device according to any one of claims 25 to 27, characterized in that:

33. Observation of the object image formed through the imaging optical system including the objective lens system In the manufacturing method of the observation device,

A method for manufacturing an observation device, wherein the objective lens system is manufactured using the manufacturing method according to any one of claims 5 to 18.

34. While suppressing the wavefront aberration due to the refractive index distribution of each optical member other than the objective lens system in the imaging optical system, and suppressing the wavefront difference of each surface of each optical member with respect to a reference surface, 34. The method for manufacturing an observation device according to claim 33, wherein each optical member is manufactured.

35. An observation apparatus according to any one of claims 24 to 32, and a projection optical system for projecting and exposing a pattern of a mask onto a photosensitive substrate. Exposure equipment.

36. The observing device may include a mark provided on the mask or a mark provided on the photosensitive substrate in order to align the mask and the photosensitive substrate with respect to the projection optical system. The method according to claim 35, wherein the observation is performed.

37. An exposure step of exposing the mask substrate to the photosensitive substrate using the exposure apparatus according to claim 35 or 36,

A developing step of developing the exposed substrate.

38. The method for manufacturing a micro device according to claim 37, wherein the observation device is manufactured using the manufacturing method according to claim 33 or 34.

39. In a method for manufacturing an observation device for observing an object image formed through an imaging optical system including an objective lens system, A design step of designing the objective lens system by suppressing at least one of a higher order component of wavefront aberration generated by optical adjustment of the objective lens system and a difference of decentering coma aberration for each wavelength;

An adjustment step of optically adjusting the objective lens system in order to correct aberrations remaining in the assembled objective lens system.

40. In the design process, when the numerical aperture on the object side of the objective lens system is NA and the center wavelength of the light used is λ1, the center thickness of each lens constituting the objective lens system and the The RMS (root mean square) value of the higher-order spherical aberration component of the wavefront aberration generated when the air spacing is changed by d (mm) is (30 · d · NA ⁶ ) · λ 40. The method for manufacturing an observation device according to claim 39, wherein the method is set to 1 or less.

41. In the design process, when the numerical aperture on the object side of the objective lens system is ΝΑ, and the center wavelength of the light used is λ1, each lens constituting the objective lens system is oriented in a direction orthogonal to the optical axis. The RMS value of the high-order coma aberration component among the wavefront aberrations generated when decentering by s (mm) along is set to (50 · s · NA ⁵ ) · λ1 or less. 41. The method for manufacturing an observation device according to claim 39 or 40.

42. In the design process, when the numerical aperture on the object side of the objective lens system is ΝΑ, and the center wavelength of the light used is λ1, each lens constituting the objective lens system is oriented in a direction orthogonal to the optical axis. Of the shortest wavelength decentered coma aberration component of the used light among the wavefront aberrations generated when the beam is decentered by s (mm) along the axis; the MS value and the RMS value of the longest wavelength decentered coma component of the used light 42. The method for manufacturing an observation device according to claim 39, wherein the absolute value of the difference is set to (50 · s · NA ³ ) · λ1 or less.

43. Observation of the object image formed through the imaging optical system including the objective lens system In the manufacturing method of the observation device,

44. In the above manufacturing process, when the wavelength of the wavefront aberration measuring light is λ, the Ρ-V value of the wavefront aberration due to the refractive index distribution of each optical member is suppressed to 0.005λ or less. A method for manufacturing an observation device according to claim 43.

45. In the above manufacturing process, when the wavelength of the wavefront aberration measuring light is λ, the RMS values of all components after correcting the tilt component and the power component from the wavefront aberration of each surface of each of the optical members with respect to the reference surface. Is suppressed to 0.0010 λ or less, the RMS value of the rotationally symmetric component of all the components is suppressed to 0.005 λ or less, and the rotationally symmetric component obtained by removing the quadratic quartic curve component from the rotationally symmetric component The RMS value of the next residual is suppressed to 0.003 λ or less, and the RMS value of the non-rotationally symmetric component after correcting the negative component from all the components is suppressed to 0.005 λ or less. 44. The method for manufacturing the observation device according to 43 or 44.

46. In the manufacturing process, when the wavelength of the wavefront aberration measurement light is λ, the RMS values of all components after correcting the tilt component and the power component from the wavefront aberration of each surface of each of the optical members with respect to the reference surface. Is suppressed to 0.0010 λ or less, the RMS value of the longitudinal aberration component of all the components is suppressed to 0.007 λ or less, and the RMS value of the longitudinal aberration higher-order component of all the components is suppressed to 0.005 λ or less. The RMS value of the transverse aberration component of all components is suppressed to 0.005 λ or less, and the RMS value of the high order transverse aberration component of all components is suppressed to 0.003 λ or less. 3. The method for manufacturing an observation device according to claim 1.

47. In the above manufacturing process, when the wavelength of the wavefront aberration measurement light is λ, the RMS values of all components after correcting the tilt component and the power component from the wavefront aberration of each surface of each of the optical members with respect to the reference surface. Was suppressed to 0.010 λ or less, and the RMS value of the component after correcting the vas component from all the components was suppressed to 0.008 λ or less, and the vas component and low-order spherical aberration component were corrected from the all components. The observation device according to claim 43 or 44, wherein the RMS value of the subsequent component is suppressed to 0.005 λ or less, and the RMS value of the high-order aberration component of all the components is suppressed to 0.003 λ or less. Manufacturing method.

48. In the manufacturing process, when the wavelength of the wavefront aberration measurement light is λ, the RMS values of all components after correcting the tilt component and the power component from the wavefront aberration of each surface of each optical member with respect to the reference surface When the wavefront aberration is represented by a Zernike polynomial, the expansion coefficient C 9 in the ninth term is suppressed to 0.009 λ or less, and the expansion coefficient in the 10 th to 36 th terms 45. The method for manufacturing an observation device according to claim 43, wherein C10 to C36 are respectively suppressed to 0.005λ or less.

49. An observation apparatus manufactured by using the manufacturing method according to any one of claims 39 to 48, and a projection optical system for projecting and exposing a mask pattern onto a photosensitive substrate. An exposure apparatus comprising:

50. An exposure step of exposing the pattern of the mask to the photosensitive substrate using the exposure apparatus according to claim 49,

And a developing step of developing the exposed substrate.