JP2002169083A - Objective optical system, aberration measuring device, projection exposing device, manufacture of those, and manufacture of micro device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an objective optical system capable of eliminating the generated fluctuation of optical characteristics such as the fluctuation of a focal position, etc., in the case an environmental temperature changes, and also, in the case the system is put in use at a differently set temperature. SOLUTION: The system includes an objective lens system L2 for converting light from an object point O to prescribed-conditioned light and a relay optical system L1 for relaying the light transmitted through the objective lens system, and the objective optical system and the relay optical system separately includes a 1st positive lens constituted of optical material having a negative index temperature coefficient and a 2nd positive lens constituted of optical material having a positive index temperature coefficient.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective optical system, an aberration measuring device having the objective optical system, and a projection exposure device having the aberration measuring device. Also, a method of manufacturing an objective optical system, a method of manufacturing an aberration measuring device having an objective optical system manufactured by this method, a method of manufacturing a projection exposure apparatus having an aberration measuring device manufactured by this method, and this method The present invention relates to a method for manufacturing a micro device using a manufactured projection exposure apparatus.

[0002]

2. Description of the Related Art In manufacturing a semiconductor element or the like in a photolithography process, a projection optical system of a projection exposure apparatus used to project and expose a pattern image of a mask onto a photosensitive substrate is caused by various factors. Various aberrations remain. Therefore, conventionally, various aberration measuring apparatuses for measuring aberration remaining in a projection optical system mounted on a projection exposure apparatus have been proposed.

[0003] Such an aberration measuring apparatus is, for example, a CCD.
And an objective optical system that guides light via an optical system to be inspected (projection optical system) to an image sensor such as the one described above. The objective optical system includes an objective lens system that converts light from an object point into light in a state of a parallel light beam, and a micro fly-eye lens provided at an exit pupil position of the objective optical system. (A microlens array).

[0004]

The above-described aberration measuring apparatus is used in a state provided in a projection exposure apparatus. However, the temperature environment used is not constant but is within a range of plus or minus several degrees Celsius. Are used in changing environments. For example, the set temperature in a clean room when an exposure apparatus is actually used varies within a range of plus or minus several degrees C. for each microdevice manufacturer that manufactures microdevices including semiconductor elements. However,
If the objective optical system in the aberration measuring device is not configured to sufficiently correspond to each of these set temperatures, optical characteristics such as the focal position of the objective lens system or the relay optical system in the objective optical system fluctuate. As a result, there is a problem that it is not possible to accurately measure the aberration of the projection optical system of the projection exposure apparatus which is the test optical system.

An object of the present invention is to provide an objective optical system capable of canceling optical fluctuations such as a change in a focal position which occur even when the environmental temperature changes (for example, when used under an arbitrary temperature). Another object of the present invention is to provide an aberration measuring device having the objective optical system and a projection exposure apparatus having the aberration measuring device. Also, a method of manufacturing an objective optical system capable of canceling a change in optical characteristics such as a focal position that occurs even when the environmental temperature changes, and a method of manufacturing an aberration measuring apparatus including the objective optical system manufactured by this method Another object of the present invention is to provide a method of manufacturing a projection exposure apparatus having an aberration measuring device manufactured by this method, and a method of manufacturing a micro device using the projection exposure apparatus manufactured by this method.

[0006]

According to a first aspect of the present invention, there is provided an objective optical system comprising: a first positive lens made of an optical material having a negative refractive index temperature coefficient; and a positive refractive index temperature coefficient. And a second positive lens composed of an optical material having the following. According to the objective optical system of the first aspect, for example, a negative (in a direction approaching the exit pupil) when a temperature change occurs in the second positive lens made of an optical material having a refractive index temperature coefficient having a positive value. The correction of the focal position fluctuation of (1) by the positive (in the direction away from the exit pupil) focal position fluctuation at the time of a temperature change generated by the first positive lens made of an optical material having a negative refractive index temperature coefficient. This makes it possible to reduce the fluctuation of the focal position when the temperature changes (for example, when using at different temperatures).

In the objective optical system according to the present invention, the focal length of the entire objective optical system is f, and the focal length of the entire objective optical system when the temperature of the entire objective optical system changes by ΔT (° C.). when was the _{f 1, | (f 1 -f} ) / f / ΔT | <10 -4
(1 / ° C.). According to the objective optical system of the second aspect, | (f ₁ −f) / f /
Since the condition of ΔT | <10 ⁻⁴ (1 / ° C.) is satisfied, it is possible to reduce the fluctuation of the focal position when the temperature changes (for example, when using at different temperatures).

The objective optical system according to a third aspect of the present invention comprises: an objective lens system for converting light from an object point into light in a predetermined state;
A relay optical system that relays light from the objective lens system, wherein the objective optical system and the relay optical system are made of an optical material having a negative refractive index temperature coefficient having a negative value.
, And a second positive lens made of an optical material having a positive refractive index temperature coefficient. According to the objective optical system of the third aspect,
For example, even when a temperature change occurs only in the objective lens system or when a temperature change occurs only in the relay optical system, the second positive lens formed of an optical material having a positive refractive index temperature coefficient has a positive temperature coefficient. The negative (in the direction approaching the exit pupil) focal position fluctuation at the time of the generated temperature change is generated by the first positive lens made of an optical material having a negative value of the refractive index temperature coefficient. Correction can be made by a change in the focal position in a direction away from the pupil), and a change in the focal position when the temperature changes (for example, when used at different temperatures) can be reduced.

Further, in the objective optical system according to the present invention, the focal length of the whole system of the objective optical system is f, and the focal length of the whole system when only the objective lens system changes in temperature by ΔT (° C.). fo, | ((fo)
−f) / f) / ΔT | <10 ⁻⁴ (1 / ° C.) and | ((fr
−f) / f) / ΔT | <10 ⁻⁴ (1 / ° C.) According to this objective optical system, | ((fo−f) / f) / ΔT | <10 ⁻⁴ (1 /
° C) and | ((fr-f) / f) / ΔT | <10 ^-4 (1 /
(° C.), it is possible to reduce the fluctuation of the focal position when the temperature changes (for example, when using at different temperatures).

The objective optical system according to claim 5, further comprising a holding member for holding the first positive lens and the second positive lens, wherein the holding member is a line of the first positive lens. It has a linear expansion coefficient (or thermal expansion coefficient) smaller than an expansion coefficient (or thermal expansion coefficient) and larger than a linear expansion coefficient (or thermal expansion coefficient) of the second positive lens. According to this objective optical system, the linear expansion coefficient of the holding member is smaller than the linear expansion coefficient of the first positive lens and larger than the linear expansion coefficient of the second positive lens. (When used at different temperatures).

In the objective optical system according to the present invention, the first positive lens and the second positive lens may provide a predetermined optical action to light having a wavelength of 300 nm or less. Is transmitted. According to the objective optical system of the sixth aspect, 30
It is possible to realize an objective optical system that is achromatized with respect to light having a wavelength of 0 nm or less.

Further, in the aberration measuring apparatus according to the present invention, a minute area in the image forming plane is set as a measurement object point in order to measure an aberration related to the image forming plane of the optical system to be measured. Item 7 includes the objective optical system according to any one of Items 6, and a photoelectric detection unit that detects light from the measurement object point via the objective optical system. According to the aberration measuring apparatus of the present invention, when the temperature changes (for example, when the objective optical system has a minute area in the imaging plane of the optical system to be measured as an object point),
Since the objective lens according to any one of claims 1 to 6 has a reduced focal position variation during use at different temperatures), the environmental temperature at which the aberration measuring device is used has changed. In this case (for example, when the temperature in the clean room is arbitrarily set within a predetermined range), accurate aberration measurement can be performed.

According to another aspect of the present invention, there is provided a projection exposure apparatus including a projection optical system for forming a pattern image of a mask on a photosensitive substrate. The measurement device measures the aberration of the projection optical system using the projection optical system as a test optical system. According to the projection exposure apparatus of the eighth aspect, the aberration measuring apparatus of the seventh aspect is included, and the aberration measuring apparatus measures the aberration of the projection optical system as the test optical system. (E.g., a set temperature in a clean room), it is possible to always accurately measure the aberration of the projection optical system as the test optical system, which is stable.

According to a ninth aspect of the present invention, in the method of manufacturing an objective optical system, a first design step of designing an objective optical system having a predetermined performance at a reference temperature is provided, and the predetermined performance is shifted from the reference temperature by a predetermined temperature. And a second design step of designing the objective optical system so as to maintain According to the method for manufacturing an objective optical system according to the ninth aspect, even when the environmental temperature (for example, the temperature in the clean room is arbitrarily set within a predetermined range) changes, the optical characteristics such as the focal position change and the like also change. Can be manufactured with a small fluctuation of the objective optical system.

According to a tenth aspect of the present invention, in the method of manufacturing an objective optical system, in the second design step, a first positive lens made of an optical material having a negative temperature coefficient of refractive index; The temperature coefficient is designed using a second positive lens made of an optical material having a positive value. According to the objective optical system manufacturing method of the tenth aspect, the first positive lens made of an optical material having a negative refractive index temperature coefficient and an optical element having a positive refractive index temperature coefficient are used. Since the design is performed using the second positive lens made of a material, the negative (exit pupil) at the time of temperature change generated in the second positive lens made of an optical material having a refractive index temperature coefficient having a positive value (A direction approaching the exit pupil) is caused by a positive (in a direction away from the exit pupil) focal position change caused by a temperature change generated by a first positive lens made of an optical material having a negative refractive index temperature coefficient. A corrected objective optics can be manufactured.

According to a eleventh aspect of the present invention, there is provided a method for manufacturing an aberration measuring apparatus, comprising the steps of: preparing an objective optical system manufactured by the method according to the ninth or tenth aspect; In order to measure the aberration associated with, the method includes a step of arranging a photoelectric detection unit at a position where light from a minute area in the image plane exits through the objective optical system. According to the method for manufacturing an aberration measuring device according to the eleventh aspect, the objective optical system manufactured by the method according to the ninth or tenth aspect uses an objective optical system having a small change in the focal position when the temperature changes. Also, it is possible to manufacture an aberration measuring device that can accurately measure aberration even when the environmental temperature changes.

According to a twelfth aspect of the present invention, there is provided a method of manufacturing a projection exposure apparatus including a projection optical system for forming a pattern image of a mask on a photosensitive substrate.
12. A step of preparing an aberration measuring device manufactured by the method according to claim 11, and a step of placing the aberration measuring device at a position where the aberration of the projection optical system is measured using the projection optical system as a test optical system. It is characterized by including. According to the manufacturing method of the projection exposure apparatus of the twelfth aspect, the aberration of the projection optical system as the test optical system which is always stable regardless of the environmental temperature or temperature change (for example, the set temperature in the clean room) can be reduced. A projection exposure apparatus capable of measuring with high accuracy can be manufactured.

According to a thirteenth aspect of the present invention, there is provided a microdevice manufacturing method, comprising: exposing a mask pattern onto a photosensitive substrate using the projection exposure apparatus according to the eighth aspect;
A developing step of developing the photosensitive substrate exposed in the exposing step.

According to a fourteenth aspect of the present invention, there is provided a microdevice manufacturing method, comprising: exposing a mask pattern onto a photosensitive substrate using a projection exposure apparatus manufactured by the method according to the twelfth aspect; A developing step of developing the photosensitive substrate exposed in the step.

According to the method for manufacturing a micro device according to the present invention, the image of the pattern of the mask can be faithfully formed on the photosensitive substrate, so that the micro device can be manufactured with high throughput. be able to.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an objective optical system according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an objective optical system OL according to the first embodiment.
FIG. 2 is a diagram showing a lens cross section of FIG. As shown in this figure,
The objective optical system OL1 collimates the light beam condensed at the object point O or the light beam emitted from the object point O onto the exit pupil P of the objective optical system OL1 formed in space without generating aberration. The optical system has a wavelength of 248 nm.
(KrF excimer laser wavelength).

That is, the objective optical system OL1 includes an afocal relay lens (relay optical system) L1 and an infinity objective lens (objective lens system) L2. The afocal relay lens L1 is sequentially arranged from the exit pupil P side. A convex lens directed to the object surface, a biconvex lens (positive lens) L11, a meniscus lens (positive lens) L12 having a concave surface facing the object surface, and biconcave lenses (negative lenses) L13 and L14. It is configured by disposing six optical members, a meniscus lens (positive lens) L15 and a biconvex lens (positive lens) L16. The infinity objective lens L2 includes a biconcave lens (negative lens) L21, a meniscus lens (positive lens) L22 having a convex surface facing the object surface, and biconvex lenses (positive lenses) L23 and L24. , A meniscus lens (positive lens) L25 to L27 having a concave surface facing the object surface, and eight optical members of a parallel plate glass L28.

Here, the afocal relay lens L1 is constructed.
Meniscus lens L12 with concave surface facing object surface to be formed
The meniscus lens L15 with the convex surface facing the object surface
Optical material having a negative refractive index temperature coefficient (dn / dT)
(GM) Fluorite (CAF _TwoOptical member using
(First positive lens), a biconvex lens L11,
L16 has a positive value of the temperature coefficient of refractive index (dn / dT).
Quartz (QUARTZ), which is an optical material (GP)
Optical member (second positive lens) used. In addition,
The biconcave lenses L13 and L14, which are other optical members,
This is an optical member using quartz.

The biconvex lens L24 and the meniscus lens L26 having a concave surface facing the object surface constitute the infinity objective lens L2. The optical material (GM) having a negative refractive index temperature coefficient (dn / dT) has a negative value. An optical member (first positive lens) using fluorite, a meniscus lens L22 having a convex surface facing the object surface, a biconvex lens L23,
Meniscus lenses L25 and L27 with concave surfaces facing the object plane
Is an optical member (second positive lens) using quartz, which is an optical material (GP) having a positive refractive index temperature coefficient (dn / dT). The biconcave lens L21 and the parallel plate glass L28, which are other optical members, are optical members using quartz.

As shown in FIG. 2, each of the optical members L11 to L16 and L21 to L28 constituting the objective optical system OL1 is
It is installed in a lens barrel (holding member) LM made of a titanium alloy. That is, the optical members L11 to L16, L21 to L28
Represents the circumference connecting the midpoints of the edge thicknesses in the optical axis direction to the lens barrel LM.
Is fixed to the inner wall. Thereby, each optical member L11
L16, L21 to L28 and the relative position of the lens barrel LM are fixed.

The barrel LM made of titanium alloy has a linear expansion coefficient (or thermal expansion coefficient) of 8.6 ppm (1 / ° C.), and a linear expansion coefficient (or thermal expansion coefficient) of an optical member using fluorite is ,twenty four
The linear expansion coefficient (or thermal expansion coefficient) of an optical member using ppm (1 / ° C.) and quartz is 0.54 ppm (1 / ° C.). That is, the linear expansion coefficient of the titanium alloy lens barrel LM is smaller than the linear expansion coefficient of the optical member using fluorite and larger than the linear expansion coefficient of the optical material using quartz.

[0027] The objective optical system OL1 is the focal length of the entire system is f, a focal length of the time the whole of the objective optical system OL1 has temperature changes by [Delta] T (° C.) when the f ₁ | ( f ₁ −f) / f / ΔT | <10 ⁻⁴ (1 / ° C.) (1)

Further, the focal length of the entire system of the objective optical system OL1 is f, the focal length of the entire system when only the infinity objective lens L2 changes in temperature by ΔT (° C.) is fo, and only the afocal relay lens L1 is Assuming that the focal length of the entire system when the temperature changes by ΔT (° C.) is fr, | ((fo−f) / f) / ΔT | <10 ⁻⁴ (1 / ° C.) (2) | (( fr−f) / f) / ΔT | <10 ⁻⁴ (1 / ° C.) (3)

Next, a method of manufacturing the objective optical system OL1 including the afocal relay lens L1 and the infinity objective lens L2 will be described with reference to FIG.

First, an objective optical system O composed of an afocal relay lens L1 and an infinity objective lens L2.
The basic design of L1 is performed (step S10). That is, the afocal relay lens L is set so as to eliminate the aberration with respect to the light of the reference wavelength (for example, 248 nm) at the reference temperature.
In addition to determining the type of glass material of each optical member (L11 to L16), the radius of curvature of the lens surface of each optical member (L11 to L16), the distance between the optical members (L11 to L16), and the like, Each optical member (L
21 to L28), the optical members (L21 to L28)
28), the curvature radius of the lens surface, and the optical members (L21 to L21)
28), etc. are determined.

Next, even when the environmental temperature in which the objective optical system OL1 is used changes by a predetermined temperature, the objective optical system OL1 maintains the predetermined performance (the objective optical system OL1).
A so-called temperature achromatic design is performed to prevent the focal length of L1 from changing (step S11). That is, when the environmental temperature changes, the type of the glass material of the optical member that has a large influence on the change in the focal position of the objective optical system OL1 among the optical members (L11 to L16) configuring the afocal relay lens L1. In addition to making the change, the radius of curvature of the lens surface of each optical member, the distance between the optical members, and the like are determined again, and the objective optical system OL1 in each of the optical members (L21 to L28) constituting the infinite objective lens L2. By changing the type of the glass material of the optical member which has a large influence on the fluctuation of the focal position, and by again determining the radius of curvature of the lens surface of each optical member, the interval between the optical members, etc., the objective optical system OL1 Perform temperature achromatization design.

As the glass material of the optical member, for example,
In the basic design of step S10, if quartz is used as the glass material of each optical member constituting the afocal relay lens L1 and the infinity objective lens L2, when the environmental temperature changes, the focal position changes. It is preferable to perform the temperature achromatization design using fluorite as the glass material of the optical member which has a great influence on the optical member.

In step S10, the temperature achromatic design for the objective optical system OL1 is performed in consideration of the material (including the linear expansion coefficient) and the shape of the lens barrel LM manufactured in step S11. Is even more preferred.
In other words, in step S10, the lens barrel L
It is preferable to perform the temperature achromatic setting for the objective optical system OL1 while taking the design of M into consideration.

Next, the optical members (L11 to L16, L21 to L28) constituting the objective optical system OL1 and the lens barrel LM for holding each optical member are manufactured (step S12). That is, in the temperature achromatic design, an optical member having a lens surface having a determined radius of curvature is manufactured using the determined glass material for each optical member. Further, a lens barrel LM for holding each optical member using a titanium alloy is manufactured.

Next, the objective optical system OL1 is assembled (step S13). That is, each optical member (L21 to L28) constituting the infinity objective lens L2 in the lens barrel LM.
Are arranged at the determined intervals, and the optical members (L11 to L16) constituting the afocal relay lens L1 are arranged at the determined intervals.

Next, adjustment of various aberrations and adjustment of the focal position are performed to make the objective optical system OL1 exhibit the designed performance (step S14). That is, odd-numbered optical members (L11, L13, L15, L15) counted from the exit pupil P side
22, L24, L26) is rotated around the optical axis to adjust the astigmatism of the objective optical system OL1. Also, three optical members (L14, L15, L1)
The spherical aberration is adjusted by integrally moving 6) along the optical axis direction. Further, the coarse adjustment of the eccentric coma can be performed by moving the optical member L21 in the direction perpendicular to the optical axis, and the fine adjustment of the eccentric coma aberration by moving the optical member L15 in the direction perpendicular to the optical axis. I do. Further, by adjusting the position of the optical members (L21 to L27 or L28) in the direction along the optical axis, coarse adjustment of the focal position is performed and the optical members (L21, L22) are adjusted.
Fine adjustment of the focal point position is performed by adjusting the position in the direction along the optical axis. When the adjustment of various aberrations and the adjustment of the focal position are completed, the manufacture of the objective optical system OL1 is completed.

The adjustment of the focal position in step S14 means that a pinhole is arranged or an object on a predetermined object plane (or a predetermined focal plane) as a reference plane on which an image plane or the like of the optical system to be measured is formed. This means adjustment to match the object-side focal position of the objective optical system OL1 or the infinity objective lens system L2 with the point O.

According to the objective optical system OL1, a negative (in a direction approaching the exit pupil P) focal position fluctuation at the time of a temperature change generated in an optical member made of an optical material having a positive refractive index temperature coefficient. Can be corrected by a positive (in a direction away from the exit pupil P) focal position change at the time of a temperature change generated by an optical member made of an optical material having a negative value of the refractive index temperature coefficient. Of the focal position at the time of a temperature change, which occurs in the whole of the image forming apparatus, can be reduced.

Further, even when a temperature change occurs only in the afocal relay lens L1 or a temperature change occurs only in the infinity objective lens L2, an optical material having a positive refractive index temperature coefficient is used. A negative (in the direction approaching the exit pupil) focal position fluctuation at the time of a temperature change generated by the optical member is positive (ejection) at the time of a temperature change generated by an optical member using an optical material having a negative value of the refractive index temperature coefficient. Correction can be made by a change in the focal position in a direction away from the pupil P), and the change in the focal position when the temperature changes can be reduced.

Also, since the optical material having a negative temperature coefficient of refractive index includes fluorite having a large absolute value of the temperature coefficient of refractive index and a large linear expansion coefficient as compared with ordinary optical materials,
It is possible to more effectively correct the change in the focal position due to the temperature change.

Further, since an optical material having a positive temperature coefficient of refractive index includes quartz having a smaller linear expansion coefficient than that of an ordinary optical material, an optical material having a positive temperature coefficient of refractive index is used. Optical member which is made of an optical material having a negative value of the refractive index temperature coefficient, which makes it possible to reduce the negative focus position fluctuation (in the direction approaching the exit pupil P) at the time of a temperature change generated by the optical member. In this case, the correction amount due to the change in the focal position in the positive direction (in the direction away from the exit pupil P) when the temperature is changed can be reduced. This makes it possible to realize a temperature-erased objective optical system without sacrificing the performance of the objective optical system before the temperature change.

The linear expansion coefficient of the titanium alloy lens barrel LM is smaller than the linear expansion coefficient of the optical member using fluorite and larger than the linear expansion coefficient of the optical material using quartz. Therefore, it is possible to reduce the fluctuation of the focal position when the temperature of the objective optical system OL1 changes.

Further, since only quartz and fluorite having a high transmittance of light having a wavelength of 300 nm or less are used as an optical material, an objective optical system which is achromatized with light having a wavelength of 300 nm or less can be realized.

Further, since the used light is monochromatic light having a wavelength of 300 nm or less, there is almost no need to consider the normal achromatizing effect of the objective lens, and it is possible to more effectively realize the correction of the change in the focal position due to the temperature change.

The objective optical system OL1 has a negative refractive index temperature coefficient (a direction approaching the exit pupil P) when a temperature change occurs in a positive lens group using an optical member (GP) having a positive value.
Is corrected by a positive (in a direction away from the exit pupil P) focal position change caused by a negative lens group using an optical material (GP) having a positive refractive index temperature coefficient. It also has an effect.

Since the objective optical system OL1 has the function of a positive lens as a whole, in the normal case, the temperature change caused by an optical member using an optical material (GP) whose refractive index temperature coefficient has a positive value occurs. The focal position fluctuation becomes negative (in a direction approaching the exit pupil P). If only the optical member using an optical material (GP) having a positive value of the refractive index temperature coefficient is used to reduce the focal position fluctuation at the time of temperature change occurring in the entire objective optical system OL1, it is necessary to reduce the negative lens. The absolute value of the focal length becomes extremely small, making it difficult to obtain good imaging performance at the reference temperature. Therefore, this objective optical system OL
In No. 1, the temperature change is performed using a positive lens using an optical material (GP) having a positive refractive index temperature coefficient and a positive lens using an optical material (GM) having a negative refractive index temperature coefficient. Since the fluctuation of the focal position at the time is reduced, the fluctuation of the focal position can be effectively reduced while maintaining the imaging performance.

In the objective optical system OL1, the object point O
Or a light beam emitted from the object point O becomes a parallel light beam after passing through the infinity objective lens L2, and is further projected on the exit pupil P of the infinity objective lens L2 by the afocal relay lens L1. Is done.

Therefore, this objective optical system OL1 is
When used as an objective lens for a wavefront aberration measuring device based on the ck-Hartman (Shack-Hartman) method, a microlens array (such as a fly-eye lens) composed of a collection of microlenses in or near the exit pupil P is used. Deploy. In addition, when used as a microscope objective lens, the object can be visually observed by arranging the pupil of the observer on the exit pupil P.

Next, the specifications of the objective optical system OL1 (reference wavelength: 248 nm) according to the first embodiment will be described. Here, for convenience of ray tracing calculation, an object is arranged at a position at infinity at the exit pupil side, and ray tracing is performed from the exit pupil side toward the object. NA is the numerical aperture of the objective optical system,
The surface number is the order of the lens surfaces of the optical member from the exit pupil side. Quartz (QU) in the material properties table below
ARTZ) and fluorite (CAF ₂ ) have a reference wavelength of 248 n
The values for m are shown.

NA = 0.83 Maximum image height = 0.02 Surface number Curvature radius Interval Member effective diameter 0 (object) ∞ １ 1 (aperture) ∞ 32.8 10.2085 2 27.171 2.6 'QUARTZ' 10.4251 3 -51.601 0.5 10.1911 4 14.097 2.5 'CAF2' 9.7119 5 113.575 3.836057 8.9656 6 -36.507 2.5 'QUARTZ' 6.7789 7 28.487 35.923 5.8668 8 -22.359 2 'QUARTZ' 8.1296 9 40.687 3.340943 9.1282 10 -85.392 3.2 'CAF2' 11.2427 11 -15.69 0.5 12.3593 12 34.809 3.1 ' QUARTZ '13.2759 13 -39.434 33.50815 13.4889 14 -18.411 2.8' QUARTZ '13.3242 15 28.75 5.367381 14.5922 16 -52.62 4.9' QUARTZ '17.2395 17 -31.799 0.598942 19.5943 18 126.027 4.7' QUARTZ '21.0032 19 -36.551 0.5 21.767 20 53.399 3.8 '22 .2127 21 -135.009 0.5 22.1164 22 15.69 4.7 'QUARTZ' 21.3812 23 33.983 0.5 20.0492 24 12.505 5 'CAF2' 18.0855 25 38.135 0.5 15.9745 26 9.141 4.2 'QUARTZ' 12.7327 27 26.266 0.932096 9.4505 28 ∞ 6 'QUARTZ' 0.9321 29 ∞ 0 0.0406 30 (image plane) ∞ 0 Material properties table Optical member Refractive index Refractive index temperature coefficient (1 / ° C ) Linear expansion coefficient (1 / ° C) 'QUARTZ' 1.50838974 14 × 10 ^-6 0.54ppm 'CAF2' 1.46788252 -7.3 × 10 ^-6 24ppm Hold member Linear expansion coefficient (1 / ° C) Titanium alloy 8.6ppm

Next, referring to FIG. 4, based on the specifications of the objective optical system OL1 according to the first embodiment, each optical member constituting the objective optical system OL1 changed by 1 ° C. independently. The focal position fluctuation at the time, that is, the fluctuation of the focal position from the rear focal position (the lens surface with the surface number 29 of the optical member L28 in FIG. 1) will be considered. In addition, since the change in the focal position occurs based on the change in the relative refractive index of the optical member, the expansion of the optical member (lens), and the expansion of the holding member, in FIG. Regarding the focal position variation when independently changing by 1 ° C., the amount of change in the focal position based on the change in the relative refractive index of the optical member, the amount of change in the focal position based on the expansion of the optical member, and the change in the focal position based on the expansion of the holding member The figure also shows the amount of change, and also shows the total amount of change in these focal positions.

As shown in FIG. 4, a negative (in a direction approaching the exit pupil P) focal point variation caused by a temperature change occurring in an optical member group using an optical material (GP) having a positive refractive index temperature coefficient. Positive (exit pupil P) when a temperature change occurs in an optical member group using an optical material (GM) having a negative refractive index temperature coefficient.
(In a direction away from the focal point), it is possible to correct the focal position fluctuation, and the focal position fluctuation at the time of temperature change occurring in the entire optical system is reduced.

Since the relative refractive index of the optical member changes based on the refractive index temperature coefficient (dn / dT) of the optical member, it satisfies Δn = (dn / dT) × ΔT. Here, Δn: refractive index change at the time of temperature change, ΔT: temperature change amount. Therefore, the amount of change in the focal position based on the change in the relative refractive index of the optical member is calculated based on Δn and the like.

Since the shape of the optical member isotropically changes according to the linear expansion coefficient (EG) of the member, ΔR = EG
× R × ΔT, ΔD = EG × D × ΔT. Where ΔR:
R: radius of curvature before temperature change, ΔD: center thickness change at temperature change, D: center thickness before temperature change, ΔT: temperature change amount. Therefore, the amount of change in the focal position based on the expansion of the optical member is calculated based on ΔR, ΔD, and the like.

Further, since the shape of the holding member isotropically changes according to the linear expansion coefficient (EM) of the holding member, ΔDM = EM
× DM × ΔT is satisfied. Here, ΔDM: change in the distance of the adjacent optical member holding point in the optical axis direction when the temperature changes,
DM: distance in the optical axis direction between adjacent optical member hold points before temperature change, ΔT: temperature change amount. Therefore, the amount of change in the focal position based on the expansion of the holding member is calculated based on ΔDM or the like. The back focal position and the wavefront aberration before and after the temperature change of 1 ° C. of the objective optical system OL1 are shown below.

23 ° C. (reference temperature) Back focal position Wavefront aberration RMS Afocal lens 0 0.0013 Ray lens (L1) Object at infinity 0 0.0013 Lens (L2) Overall (OL1) 0 0.0013 (* λ: λ = 248 * 10) ^-6 ) 24 ° C (+ 1 ° C) Back focal point Wavefront aberration RMS Afocal lens 0.00001 0.0016 Ray lens (L1) Infinity objective 0.000008 0.0014 Lens (L2) Overall (OL1) 0.000018 0.0019 (* λ: λ = 248 * 10) ^-6 )

Since the focal length of the objective optical system OL1 according to this embodiment is −6.15, equation (1) is 2.9 × 10 ⁻⁶ (2) is 1.6 × 10 ⁻⁶ (3) is 1.3 × 10 ⁻⁶ , which satisfies the above conditional expression.

Next, an objective optical system according to a second embodiment of the present invention will be described. FIG. 5 is a diagram illustrating a lens cross section of the objective optical system OL2 according to the second embodiment. As shown in this figure, this objective optical system OL2 is
Similarly to the objective optical system OL1 according to the first embodiment, an exit pupil arranged in a space without generating aberration of a light beam focused on an object point O or a light beam emitted from the object point O. An optical system that collimates to P and has a reference wavelength of 19
The optical system uses 3 nm light (light from an ArF excimer laser).

More specifically, the afocal relay lens L1 includes an afocal relay lens L1 and an infinity objective lens L2. The afocal relay lens L1 includes a biconvex lens (positive lens) L11 and a concave surface , A meniscus lens (positive lens) L12, biconcave lenses (negative lenses) L13 and L14, a meniscus lens (positive lens) L15 with a convex surface facing the object surface, and a biconvex lens (positive lens) ) Six optical members L16 are arranged. The infinity objective lens L2 includes a biconcave lens (negative lens) L21, a meniscus lens (positive lens) L22 having a convex surface facing the object surface, and biconvex lenses (positive lenses) L23 and L24. , A meniscus lens (positive lens) L25 to L27 having a concave surface facing the object surface, and eight optical members of a parallel plate glass L28.

Here, the meniscus lens L15 having a convex surface facing the object surface and the biconvex lens L16 constituting the afocal relay lens L1 have a refractive index temperature coefficient (dn / dn).
dT) is an optical member (first positive lens) using fluorite (CAF ₂ ) which is an optical material (GM) having a negative value, and has a biconvex lens L11 and a concave surface facing the object surface. The meniscus lens L12 has a refractive index temperature coefficient (dn /
dT) is an optical member (second positive lens) using quartz (QUARTZ), which is an optical material (GP) having a positive value. The biconcave lenses L13 and L14, which are other optical members, are optical members using quartz.

The biconvex lens L24 and the meniscus lens L26 having a concave surface facing the object surface constitute the infinity objective lens L2. An optical member (first positive lens) using fluorite, a meniscus lens L22 having a convex surface facing the object surface, a biconvex lens L23,
Meniscus lenses L25 and L27 with concave surfaces facing the object plane
Is an optical member (second positive lens) using quartz, which is an optical material (GP) having a positive refractive index temperature coefficient (dn / dT). The biconcave lens L21 and the parallel plate glass L28, which are other optical members, are optical members using quartz.

The objective optical system O according to the second embodiment
Similarly to the objective optical system OL1 according to the first embodiment, the optical members L11 to L16 and L21 to L28 are installed in a titanium alloy lens barrel (holding member) LM. It is manufactured in the same manner as the objective optical system OL1 of the embodiment. However, the objective optical system OL2 has a wavelength of 193.
Since the optical system uses light of nm, each optical member (L11 to L16) constituting the afocal relay lens L1 and each constituting the infinity objective lens L2 in a basic design in the case of manufacturing an objective optical system. Optical members (L21 to L21)
Quartz and fluorite are used as the type of glass material of L28). Then, when the environmental temperature changes, each optical member (L11 to L1) constituting the afocal relay lens L1 is changed.
6), each optical member (L
In 21-L28), the type of the glass material of the optical member that has a large influence on the change in the focal length of the objective optical system OL2 is changed, and a temperature achromatic design is performed on the objective optical system OL2.

Further, similarly to the objective optical system OL1 according to the first embodiment, the objective optical system OL2 has a focal length f of the entire system, and the entire objective optical system OL has a temperature of ΔT (° C.). a focal length of the time that has changed is taken as _{f 1 | (f 1 -f)} / f / ΔT | satisfies the condition of ^{<10 -4 (1 / ℃)} ... (1), the objective optical system The focal length of the entire system of OL is f, the focal length of the entire system when only the infinity objective lens L2 has changed in temperature by ΔT (° C.) is fo, and only the afocal relay lens L1 has changed in temperature by ΔT (° C.). | ((Fo−f) / f) / ΔT | <10 ⁻⁴ (1 / ° C.) (2) | ((fr−f) / f) / ΔT | <10 ⁻⁴ (1 / ° C.) (3)

The objective optical system OL2 has an effect of canceling the change in the focal position that occurs when the environmental temperature used changes, similarly to the objective optical system OL1 according to the first embodiment.

Next, the specifications of the objective optical system OL2 (reference wavelength: 193 nm) according to the second embodiment will be described. Here, for the sake of ray tracing calculation, an object is arranged at a position at infinity at the exit pupil side, and ray tracing is performed from the exit pupil side toward the object. Here, NA is the numerical aperture of the objective optical system, and the surface number is the order of the lens surfaces of the optical member from the exit pupil side. In addition, the refractive indexes of quartz (QUARTZ) and fluorite (CAF ₂ ) in the material properties table listed below are based on the reference wavelength of 19
The values for 3 nm are shown.

NA = 0.81 Maximum image height = 0.02 Surface number Curvature radius Interval Member effective diameter O (object) ∞ ∞ 1 (stop) ∞ 32.8 10.2448 2 24.9311 2.8 'QUARTZ' 10.4558 3 -68.099 0.5 10.149 4 16.499 2.6 'QUARTZ' 9.6937 5 152.583 3.75207 8.8711 6 -40.229 2.2 'QUARTZ' 6.5748 7 23.345 33.8427 5.7283 8 -35.895 2.2 'QUARTZ' 7.6089 9 51.09 4.105231 8.4456 10 -47.655 3.5 'CAF2' 10.7161 11 -16.9872 0.5 12.0333 12 46.425 4 ' CAF2 '12.7636 13 -31.24 33.2528 13.1635 14 -25.127 3' QUARTZ '12.9978 15 23.897 4.770544 13.9151 16 -44.905 4' QUARTZ '16.032 17 -34.444 1.020096 18.0593 18 88.499 4.5' QUARTZ '19.7264 19 -55.875 0.5 20.5898 20 47.078 5CA '21 .2319 21 -72.192 0.5 21.2387 22 15.69 4.7 'QUARTZ' 20.4905 23 27.206 0.5 18.7904 24 12.505 5 'CAF2' 17.3464 25 43.598 0.5 15.1802 26 9.141 4 'QUARTZ' 12.1469 27 20.872 1.007804 8.8209 28 ∞ 6 'QUARTZ' 7.3357 29 ∞ 0 0.04 30 (image surface) ∞ 0 0.04 Material properties table Optical member Refractive index Refractive index temperature coefficient (1 / ° C) Linear expansion Number (1 / ℃) 'QUARTZ' 1.5603261 19.5 × 10 -6 0.54ppm 'CAF2' 1.5014548 -2.9 × 10 -6 24ppm holding member linear expansion coefficient (1 / ° C.) titanium alloy 8.6ppm

Next, referring to FIG. 6, this objective optical system O
Based on the specifications of L2, each optical member has a temperature of 1 ° C. independently.
Consider a change in the focal position when it changes, that is, a change in the focal position from the rear focal position (the lens surface of surface number 29 of the optical member L28 in FIG. 5). In FIG. 6, as in FIG. 4, for each optical member, regarding the focal position fluctuation when each optical member changes by 1 ° C. independently, the focal position fluctuation based on the change in the relative refractive index of the optical member. The figure also shows the amount, the amount of change in the focal position based on the expansion of the optical member, and the amount of change in the focal position based on the expansion of the holding member, and also shows the sum of the amounts of change in these focal positions.

As shown in FIG. 6, a negative (in a direction approaching the exit pupil P) focal position fluctuation caused by a temperature change generated by an optical member using an optical material (GP) having a positive refractive index temperature coefficient. Can be corrected by a positive (in a direction away from the exit pupil (P)) focal position change caused by an optical member using an optical material (GM) having a negative refractive index temperature coefficient. The focal position fluctuation at the time of a temperature change occurring as a whole is reduced. This objective optical system OL
The back focal position and wavefront aberration per 1 ° C. temperature change of No. 2 are shown below.

[0069]

The focal length of this objective optical system OL2 is -6.32.
Therefore, the expression (1) is 1.5 × 10 ⁻⁶ , the expression (2) is 1.3 × 10 ⁻⁶ , and the expression (3) is 0.2 × 10 ⁻⁶ , which satisfies the above conditional expression.

Next, the objective optical system OL1 according to the first embodiment and the objective optical system OL2 according to the second embodiment are described.
Is used as an objective optical system for a wavefront aberration measuring apparatus based on the Shack-Hartman method.

FIG. 7 is a diagram schematically showing the configuration of a projection exposure apparatus provided with a wavefront aberration measuring apparatus based on the Shack-Hartman system including the objective optical system OL1 or OL2. In FIG. 7, the Z axis is set along the normal direction of the wafer W as a photosensitive substrate, and FIG.
7 in the direction parallel to the paper surface of FIG.
The X-axis is set in a direction perpendicular to the paper surface of FIG. Note that FIG. 7 shows a state at the time of aberration measurement in which the sign plate of the wavefront aberration measuring device is positioned on the image plane of the projection optical system PL. At the time of projection exposure, the wafer W is positioned on the image plane of the projection optical system PL.

The projection exposure apparatus shown in FIG. 7 uses exposure light (illumination light).
, For example, 248 nm
(KrF excimer laser) or an excimer laser light source for supplying light having a wavelength of 193 nm (ArF excimer laser). The substantially parallel light beam emitted from the light source 1 is
After being shaped into a light beam having a predetermined cross section via the beam shaping optical system 2, the light beam enters the coherence reducing unit 3. The coherence reducing unit 3
It has a function of reducing the occurrence of an interference pattern on the mask M (and, consequently, on the wafer W), which is the irradiated surface. The details of the interference reducing unit 3 are described in, for example, JP-A-59-226.
No. 317 is disclosed.

The light beam from the coherence reducing unit 3 passes through a first fly-eye lens (first optical integrator) 4 to form a large number of light sources on the rear focal plane. After being deflected by the oscillating mirror 5, the light from these multiple light sources illuminates the second fly-eye lens (second optical integrator) 7 in a superimposed manner via the relay optical system 6. Here, the vibrating mirror 5 is a bending mirror that rotates around the X axis and has a function of reducing the occurrence of an interference pattern on the irradiated surface. In this way, a secondary light source including a large number of light sources is formed on the rear focal plane of the second fly-eye lens 7. The light beam from the secondary light source is limited by an aperture stop 8 disposed in the vicinity thereof, and then is uniformly illuminated via a condenser optical system 9 with a mask M having a predetermined pattern formed on a lower surface in a superimposed manner. I do.

The first and second optical integrators (4, 7) are not limited to fly-eye lenses, but are micro fly-eye lenses (micro-lens arrays) composed of an aggregate of smaller optical elements. An internal reflection type rod-shaped integrator (an internal reflection type glass rod, an internal reflection type hollow optical member), a diffractive optical element, or the like can be used.

The light flux transmitted through the pattern of the mask M forms an image of the mask pattern on the wafer W as a photosensitive substrate via the projection optical system PL. The mask M is mounted on a mask stage MS via a mask holder (not shown). The mask stage MS is driven by a mask stage controller (not shown) based on a command from a main control system (not shown). At this time, the movement of the mask stage MS is measured by a mask interferometer (not shown) and a moving mirror (not shown) provided on the mask stage MS.

On the other hand, the wafer W is vacuum chucked by the wafer holder WH on the wafer stage WS. Wafer stage WS is driven by a wafer stage control unit (not shown) based on a command from a main control system (not shown). At this time, the movement of the wafer stage WS is measured by the wafer interferometer WIF and the moving mirror WM provided on the wafer stage WS. Thus, the wafer stage WS has a moving function in the X direction, a moving function in the Y direction, a moving function in the Z direction, a rotating function around the Z axis, a tilt function around the X axis, and a tilt function around the Y axis. Interferometer W
The position is controlled in nano order by the IF and the wafer stage control unit.

The projection exposure apparatus shown in FIG. 7 is an off-axis type as a first position detection system for detecting the position of the wafer W along a plane perpendicular to the optical axis AX of the projection optical system, that is, an XY plane. (Field Image Alignment) system. The FIA system includes, for example, a halogen lamp (not shown) as a light source for supplying illumination light having a wide wavelength bandwidth. Illumination light from the light source enters the light guide 21 via a relay optical system (not shown). The light that has propagated inside the light guide 21 enters the half prism 24 via the condenser lens 22 and the relay lens 23.

The illumination light reflected by the half prism 24 is applied to each alignment mark (for example, a line and space pattern in the X direction and a line in the Y direction) formed on the wafer W through the first objective lens 25 and the reflection prism 26. And space pattern). The reflected light from each of the illuminated alignment marks enters the half prism 24 via the reflection prism 26 and the first objective lens 25. The light transmitted through the half prism 24 is
The light enters the half prism 28 via the second objective lens 27. The light transmitted through the half prism 28 is in the X direction CC
D29, the light reflected by the half prism 28 is Y
The direction CCD 30 is reached.

Here, the image pickup surface of the X-direction CCD 29 has X
An enlarged image of the direction alignment mark is formed,
An enlarged image of the Y-direction alignment mark is formed on the imaging surface of the CD 30. By processing the image signals obtained by the X-direction CCD 29 and the Y-direction CCD 30 in this manner, the position of each alignment mark along the XY plane, and thus the position of the wafer W along the XY plane, are detected. Then, the alignment of the wafer W along the XY plane can be performed based on the detected position information of each alignment mark. For details of the FIA system, see, for example, JP-A-4-65603 or
-273246.

Further, the projection exposure apparatus shown in FIG. 7 uses a so-called oblique incidence type as a second position detection system for detecting the position of the wafer W along the direction of the optical axis AX of the projection optical system, that is, the Z direction. It has a dimensional autofocus system (AF system).
The oblique incidence type two-dimensional AF system includes, for example, a halogen lamp (not shown) as a light source for supplying white light having a wide wavelength width as detection light. Illumination light from a light source is transmitted through a light guide 3 via a relay optical system (not shown).
Incident on 1. The light that has propagated inside the light guide 31 is converted into a substantially parallel light beam via the condenser lens 32, and then enters the deflection prism 33. The deflecting prism 33 deflects the substantially parallel light beam from the condenser lens 32 by a refraction action. The deflection prism 33
On the emission side, a transmission type lattice pattern in which elongated transmission portions extending in the X direction and elongated light shielding portions extending in the X direction are alternately provided at a constant pitch is formed.

The light transmitted through the transmission grating pattern of the deflecting prism 33 is incident on a projection condenser lens 34 arranged along an optical axis parallel to the optical axis AX of the projection optical system PL.
The light beam passing through the projection condenser lens 34 reaches the wafer W at a required incident angle via the mirror 35 and the projection objective lens 36. Thus, the primary image of the lattice pattern as the two-dimensional slit projection pattern is accurately formed over the entirety of the wafer W. The light reflected by the wafer W is incident on the light-receiving condenser lens 39 via the light-receiving objective lens 37 and the vibration mirror 38. The light having passed through the light-receiving condenser lens 39 is incident on a tilt correction prism 40 having the same configuration as the above-described deflection prism 33.

Thus, a secondary image of the lattice pattern is formed on the incident surface of the tilt correction prism 40. Note that a two-dimensional light receiving slit as a light blocking means is provided on the incident surface of the tilt correction prism 40. Light emitted from the exit surface of the tilt correction prism 40 enters a relay optical system 41 including a pair of lenses. The light passing through the relay optical system 41 forms a conjugate image of the secondary image of the lattice pattern formed on the incident surface of the tilt correction prism 40 and the opening of the light receiving slit on the light receiving surface of the light receiving unit 42. .
A plurality of silicon photodiodes as a two-dimensional light receiving sensor are provided on the light receiving surface so as to optically correspond to the plurality of openings of the light receiving slit.

The exit surface of the deflecting prism 33 on which the grating pattern is formed, the exposure surface of the wafer W, the entrance surface of the tilt correction prism 40 on which the two-dimensional light receiving slit is formed, and the exposure surface of the wafer W are Scheimpflug. The conjugate relationship satisfies the condition. Here, when the wafer W moves up and down in the Z direction along the optical axis AX of the projection optical system PL, the secondary image of the grid pattern formed on the incident surface of the tilt correction prism 40 moves up and down of the wafer W. Correspondingly, lateral displacement occurs in the pattern pitch direction.

Thus, the lateral displacement of the secondary image of the lattice pattern is photoelectrically detected based on the principle of the photoelectric microscope, and the surface position of the wafer W along the optical axis AX of the projection optical system PL is determined based on the detected lateral displacement. To detect. Further, the surface position of the wafer W along the optical axis AX of the projection optical system PL is detected two-dimensionally according to the two-dimensional multipoint autofocus method. As a result, the surface position of the wafer W can be two-dimensionally aligned in the focus direction of the projection optical system PL by moving the wafer stage WS in the Z direction or tilting the wafer stage WS around the X axis and the Y axis. . For details of the principle of the photoelectric microscope, see, for example, JP-A-56-42205.
No. 6,086,045. For details of the two-dimensional multipoint autofocus method, see, for example, JP-A-6-970.
No. 45 discloses this.

As described above, in the projection exposure apparatus of FIG. 7, exposure is performed by positioning the mask M and the wafer W with respect to the projection optical system PL with high accuracy. In addition, the replaced mask M and the wafer W are aligned with high accuracy, and the overlapping exposure is repeated. At this time, when replacing the wafer W, the above-described FI
The position of the wafer W is detected with high accuracy by the A system and the two-dimensional AF system. Then, the position control of the wafer W is performed with high accuracy by the wafer interferometer WIF and the wafer stage control unit. In this manner, various patterns are formed in each exposure region of the wafer W by repeating the over-exposure on the wafer W.

This projection exposure apparatus includes a wavefront aberration measuring device manufactured by the method shown in FIG. 3 for measuring the wavefront aberration of the projection optical system PL. FIG. 8 is a diagram schematically showing a configuration of a main part of the wavefront aberration measuring device of FIG.
FIG. 3 is a diagram showing a state where the aberration measurement system is developed along the optical axis. Hereinafter, the configuration of the wavefront aberration measuring device will be described with reference to FIGS. In this wavefront aberration measuring apparatus, a test mask TM for measuring aberration is set on a mask stage MS when measuring the wavefront aberration of the projection optical system PL as the test optical system. Test mask TM
As shown in FIG. 9, a plurality of circular apertures 10a for measuring aberration are provided along the X direction and the Y direction (in FIG.
Pieces) are formed in a matrix. Opening 1
A square opening 10b substantially larger than 0a is formed.

The wavefront aberration measuring apparatus includes a sign plate 11 mounted on the wafer stage WS at substantially the same height position (position in the Z direction) as the exposure surface of the wafer W. The marking plate 11 is made of, for example, a glass substrate, and has a reference plane 11a perpendicular to the optical axis AX of the projection optical system PL, and further perpendicular to the optical axis AX1 of the later-described aberration measuring system. On this reference plane 11a, as shown in FIG.
A calibration opening (light transmitting portion) 11b is formed in the center, and a plurality of sets (four in FIG. 10) of alignment marks 11c are formed around the opening.

Here, the calibration opening 11b is formed in the opening 1 of the test mask TM formed through the projection optical system PL.
It is set larger than the image of 0a. Each set of alignment marks 11c is composed of a line and space pattern formed along the X direction and a line and space pattern formed along the Y direction. Further, a reflection surface 11d is formed in a region excluding the calibration opening 11b and the plurality of alignment marks 11c. The reflection surface 11d is formed, for example, by depositing chromium (Cr) on a glass substrate.

Further, the wavefront aberration measuring device has an aberration measuring system as an optical system for measuring the wavefront aberration of the projection optical system PL. In the aberration measurement system, the projection optical system PL
The light from the image of the opening 10a of the test mask TM formed on the image surface of the test mask TM through the infinity objective lens L2 and the afocal relay lens L1 constitutes an aggregate of a large number of micro optical elements. The light enters a micro fly's eye lens (micro lens array) 14. The objective optical system constituted by the infinity objective lens L2 and the afocal relay lens L1 uses the objective optical system OL1 shown in FIG. 1 when 248 nm (KrF) is used as the exposure light of the projection exposure apparatus. 193n as the exposure light
When m (ArF) is used, the objective optical system OL2 shown in FIG. 5 is used. The micro fly's eye lens (micro lens array) 14 is arranged so that its entrance surface is located at or near the exit pupil P of the objective optical systems LO1 and OL2.

As shown in FIG. 11, the micro fly's eye lens (micro lens array) 14 is an optical element composed of a large number of minute lenses 14a having a positive refracting power and arranged squarely and vertically and horizontally. . The micro fly's eye lens (micro lens array) 14 functions as a wavefront dividing member, and is formed by, for example, performing etching on a parallel flat glass plate to form a micro lens group.

Therefore, the light beam incident on the micro fly's eye lens (micro lens array) 14 is two-dimensionally divided by a large number of micro lenses 14a,
4a, one opening 10 is provided in the vicinity of the rear focal plane.
The image of a is formed. In other words, in the vicinity of the rear focal plane of the micro fly's eye lens (micro lens array) 14, many images of the opening 10a are formed. A large number of images formed in this way are stored in a CCD as a two-dimensional image sensor.
15 detected. The output of the CCD 15 is supplied to a signal processing unit 19. As described above, the micro fly's eye lens (micro lens array) 14 splits the light from the primary image of the opening 10a of the test mask TM formed on the image plane of the projection optical system PL by wavefront splitting, and the opening 10a
Constitute a wavefront splitting element for forming a large number of secondary images.

The CCD 15 is a micro fly's eye lens (micro lens array) as a wavefront dividing element.
14 constitute a photoelectric detector for photoelectrically detecting a large number of secondary images of the opening 10a. Furthermore, an infinity objective lens L2, an afocal relay lens L1,
Micro fly eye lens (micro lens array) 1
As shown in FIG. 7, the CCD 4 and the CCD 15 are provided inside the mask stage MS, and constitute an aberration measuring system as an optical system for measuring the wavefront aberration of the projection optical system PL. Note that the above-described sign plate 11 is provided with an aberration measurement system (L2, L
1, 14, 15).

Generally, in a projection exposure apparatus, an illumination system (1 to
The numerical aperture (NA) of the illumination light supplied from 9) is set smaller than the object-side numerical aperture of the projection optical system PL. Therefore, even if the illumination system (1 to 9) is used to illuminate the opening 10a of the test mask TM, the light passing through the opening 10a enters the projection optical system PL with an insufficient numerical aperture.
Therefore, in order to illuminate the aperture 10a with a numerical aperture NAi equal to or larger than the object-side numerical aperture NAp of the projection optical system PL (incoherent illumination), the wavefront aberration measuring apparatus as shown in FIG. 9) is provided in the optical path between the test mask TM and the lemon skin plate 16 which is disposed so as to be detachable and diffuses a light beam.

FIG. 12 is a diagram showing the scattering characteristics when a parallel light beam enters the lemon skin plate. FIG.
Are the luminance distribution in the illumination NA of the light beam incident on the test mask when the lemon skin plate is not installed, and the illumination N of the light beam incident on the test mask when the lemon skin plate is installed.
FIG. 6 is a diagram comparing a luminance distribution in A. FIG. 12 and FIG.
Referring to FIG. 3, when the lemon skin plate 16 is provided to increase the numerical aperture of the light beams from the illumination systems (1 to 9), the luminance characteristics of the illumination light beams are deteriorated. Therefore, in the illumination optical path of the illumination system (1 to 9), for example, a density filter which is removably disposed near the aperture stop 8 where the secondary light source is formed and forms a light beam having a predetermined light intensity distribution. 17 are provided.

Here, a lemon skin plate 16 having a scattering characteristic of a normal distribution shape as shown in FIG.
By applying the transmittance distribution having the inverse normal distribution shape as shown in FIG. 4 to the density filter 17, the luminance characteristics of the illumination light flux deteriorated by the lemon skin plate 16 can be made substantially uniform. Alternatively, by installing a ring-shaped aperture stop having a ring-shaped opening instead of the aperture stop 8 and limiting the secondary light source to a ring-like shape, illumination deteriorated by the lemon skin plate 16 as shown in FIG. It is also possible to make the luminance characteristics of the light flux almost uniform. Of course, the installation of the density filter 17 and the installation of the annular aperture stop 8a having the annular opening can also be used in combination.

As described above, the lemon skin plate 16 and the density filter 17 (and, if necessary, the annular aperture stop 8a)
It constitutes a numerical aperture expanding means for expanding the numerical aperture of the light flux from the illumination system (1 to 9). The lemon skin plate 16 constitutes a diffusing optical member that is disposed removably in the optical path between the illumination system (1 to 9) and the test mask TM and diffuses a light beam. The density filter 17
(If necessary, the annular aperture stop 8a) constitutes a luminance characteristic equalizing means for equalizing the luminance characteristic of the illumination light flux deteriorated by the lemon skin plate 16. Instead of installing the lemon skin plate 16, the upper surface of the test mask TM can be subjected to lemon skin processing.

In general, the scattering characteristics of the lemon skin plate can be changed to some extent by the surface roughness of the grindstone when making the lemon skin plate and the difference in processing time when the surface is chemically treated with acid. In place of the lemon skin plate 16, a DOE (diffractive optical element: diffractive optics element), which is currently undergoing remarkable technological advancement, is used.
It is also possible to maintain substantially uniform luminance characteristics of the light beam having the increased numerical aperture in the illumination NA. The DOE is usually formed by forming a diffraction pattern on a glass plate by photolithography, and a DOE having a characteristic of making the luminance characteristic of scattered light almost uniform up to a certain angle has also been developed. Therefore, when the DOE is used as the diffusion optical member, the installation of the density filter 17 and the installation of the annular aperture stop 8a having the annular opening can be omitted. In recent years, the numerical aperture of illumination light supplied from the illumination system of the projection exposure apparatus tends to increase. Here, when the numerical aperture of the illumination light supplied from the illumination system of the projection exposure apparatus is set to be sufficiently larger than the object-side numerical aperture of the projection optical system PL (for example, when σ ≧ 1),
The measurement can be performed without using the lemon skin plate 16 as the numerical aperture expanding means.

In this projection exposure apparatus, as described above, the aperture 10a is illuminated with the numerical aperture NAi equal to or more than the object-side numerical aperture NAp of the projection optical system PL. In this case, FIG.
As shown in (1), it is possible to consider that a number of imaging optical systems independent of each other exist for each microlens 14a of the micro fly's eye lens (microlens array) 14 of the aberration measurement system. Each imaging optical system is provided with each micro lens 14a.
Is incoherently imaged under the influence of a part of the wavefront aberration corresponding to the size of the aperture 10a. At this time, the aberration measuring system, as shown in FIG.
0a is set to be formed. That is,
The calibration opening 11b is set substantially larger than the image 10i of the opening 10a formed via the projection optical system PL.

Considering the imaging theory, when the wavefront aberration has a tilt component (tilt component), it is obvious that the image formed via each minute lens 14a shifts in position. That is, an image position shift occurs with respect to the average amount of wavefront tilt. In other words, a position shift of an image corresponding to a partial wavefront tilt amount occurs for each imaging optical system. The state of each image at this time is the same as the state of a conventional point image formed based on a spherical wave generated by using a minimum pinhole. Therefore, the wavefront aberration can be measured by the same signal processing as in the related art.

Specifically, when the wavefront aberration does not remain in the projection optical system PL, the center of gravity of the amount of light of each image of the opening 10a is formed at each origin position for measurement. As will be described later, when there is no error due to wavefront aberration or the like in the aberration measurement system, each origin position for measurement is set on the optical axis of each microlens 14a of the micro fly's eye lens (microlens array) 14. You. Actually, since the wavefront aberration remains in the projection optical system PL, the position of the center of gravity of the amount of light of each image of the opening 10a is displaced from the position of each origin for measurement. Therefore, the wavefront aberration of the projection optical system PL is measured based on the above-mentioned positional deviation information included in the output of the CCD 15.

However, in this aberration measuring system, the CCD 15
In this method, the aperture 10a having a resolvable size is formed into an image. Therefore, it is not necessary to form the aperture 10a as a very small pinhole and generate a spherical wave as in the related art.
That is, in the prior art, it is necessary to form a very small pinhole having a high roundness in order to generate an accurate spherical wave.
In this aberration measurement system, the shape of the opening 10a is not limited to a circular shape. Further, the CCD 15 is moved from the opening 10a.
The transmittance in the optical path up to this point is determined depending on the transmittance of the optical member constituting the aberration measuring system, and does not cause deterioration in luminance due to diffraction as in the case of the related art using a minimum pinhole. As a result, it is possible to provide the CCD 15 serving as an image pickup device with an illuminance that is significantly larger than that in the case of the related art using a very small pinhole.

Next, a method of manufacturing the wavefront aberration measuring device will be described with reference to the flowchart shown in FIG. First, the objective optical system (OL) manufactured by the method shown in FIG.
1 or OL2) is prepared (step S20). next,
In order to measure aberration on the image plane of the projection optical system PL of the projection exposure apparatus, which is an optical system to be inspected, light from a minute area in the image plane is passed through the objective optical system (OL1 or OL2). The CCD 15 is arranged at the position where the light is emitted (step S
21). This completes the manufacture of the aberration measuring device.

Next, a method of manufacturing a projection exposure apparatus will be described with reference to the flowchart shown in FIG. First,
An aberration measuring device manufactured by the method shown in FIG. 18 is prepared (Step S30). Next, the aberration measuring device is arranged at a position where the aberration of the projection optical system PL is measured using the projection optical system PL of the projection exposure apparatus as a test optical system (step S30).
Thus, the manufacture of the projection exposure apparatus is completed.

The operation for measuring the wavefront aberration of the projection optical system PL using the wavefront aberration measuring device manufactured by the method shown in FIG. 18 will be described below. Sign board 1 as described above
1 is integrally attached to the aberration measurement system (L2, L1, 14, 15). Then, the reference plane 1 of the sign plate 11
An alignment mark 11c is formed on the surface 1a by etching a chromium film or the like, and a reflection surface 11d processed with necessary and sufficient surface accuracy is formed. Therefore, the above-described FIA mounted on the projection exposure apparatus
Based on the alignment mark 11c, X
The position of the sign plate 11 along the Y plane and thus the position of the aberration measurement system along the XY plane can be detected.

Using the oblique incidence type two-dimensional AF system mounted on the projection exposure apparatus, a light beam is incident on the reflecting surface 11d from an oblique direction, and based on the light beam reflected on the reflecting surface 11d, Z The surface position of the sign plate 11 along the direction, and thus the position of the aberration measurement system in the Z direction, the inclination around the X axis, and the Y position
The inclination around the axis can be detected. Further, by the operation of the wafer interferometer WIF and the wafer stage drive unit mounted on the projection exposure apparatus, alignment (position alignment) and position control with as high accuracy as the wafer W can be performed quickly.

If the aberration measurement system is displaced in the X direction, the Y direction, the Z direction or the like with respect to the projection optical system PL which is the test optical system, a low-order wavefront such as a tilt component or a defocus component is generated. A large aberration component occurs. Therefore, in order to measure the wavefront aberration, it is necessary to drive the displacement of the aberration measurement system into the wavefront aberration measurement stroke. Further, in order to improve the measurement accuracy of the wavefront aberration, it is desirable to measure the wavefront aberration in a state where the above-mentioned low-order wavefront aberration component is driven as much as possible. By installing the sign plate 11, accurate and quick position control of the aberration measurement system becomes possible,
The above-mentioned rush operation becomes easy. As a result, it is possible to improve the absolute position measurement of the focus plane of the projection optical system PL and the accuracy of measuring the absolute value of distortion.

Specifically, the wafer stage WS is driven to move the aberration measuring system into the exposure field of the projection optical system PL.
Eventually, it is moved into the detection visual field region of the two-dimensional AF system.
In this state, the reference plane 11a of the sign plate 11 is aligned with the image plane of the projection optical system PL using a two-dimensional AF system. That is, the position of the reference plane 11a of the sign plate 11 along the Z direction, the inclination around the X axis, and the inclination around the Y axis are detected so that the reference plane 11a substantially coincides with the image plane of the projection optical system PL. Adjust the alignment. Next, the wafer stage WS is driven along the XY plane, and the aberration measurement system is
It is moved into the detection field of view of the A system. Then, by using the FIA system to detect the position of the alignment mark 11c on the marking plate 11, the X-axis of the optical axis AX1 of the aberration measurement system is detected.
A position along the Y plane is detected.

The positional relationship information between the alignment mark 11c on the marking plate 11 and the optical axis AX1 of the aberration measurement system is previously recognized as data by control software as in normal wafer alignment. Further, since there are a plurality of sets of the alignment marks 11c, more accurate position detection can be performed by EGA (Enhanced Global Alignment), that is, by an averaging effect of a plurality of data. Thus, of the plurality of openings provided in test mask TM, first opening 10 arbitrarily selected.
The aberration measurement system is initially positioned at a position where the image a is formed via the projection optical system PL.

That is, in a state where the aberration measuring system is initially accurately positioned, the center point of the image of the first opening 10a formed via the projection optical system PL and the optical axis AX1 of the aberration measuring system Coincide in the XY plane. That is,
As shown in FIG. 17, the center point of the image 10i of the opening 10a coincides with the center point of the calibration opening 11b of the sign board 11 in the XY plane. In this initial state, the CCD
The wavefront aberration of the projection optical system PL is measured based on the output of No. 15. From this measurement result, a tilt component, a power component (defocus component), and an astigmatic difference component (as component) are obtained. , Can be obtained from the astigmatic difference component.

Next, the aberration measuring system is finely moved so that the tilt component and the power component become as small as possible. At this time, the absolute value of distortion is obtained based on the fine movement amount Δx in the X direction and the fine movement amount Δy in the Y direction of the aberration measurement system, and the absolute position of the focus surface is obtained based on the fine movement amount Δz in the Z direction of the aberration measurement system. You can also. In this way, the wavefront aberration of the projection optical system PL is finally measured with high accuracy based on the output of the CCD 15 with the tilt component and the power component reduced as much as possible.

The above-described operation of measuring the wavefront aberration is similarly performed sequentially on the remaining plural openings provided in the test mask TM. After the position setting of the aberration measurement system with respect to the first opening of the test mask TM using the marking plate 11 is completed, the two-dimensional AF system is used similarly to the original printing operation of the projection exposure apparatus. The height position of the marking plate 11 is always adjusted, and the position of the wafer stage WS along the XY plane is controlled based on the output information of the wafer interferometer WIF, so that the wavefront at an arbitrary coordinate position of the projection optical system PL is controlled. Aberration measurement (ie, measurement of wavefront aberration with respect to the remaining openings of the test mask TM) can be performed.

As described above, the aberration measuring system is finely moved by a desired value based on the tilt component and the power component, which are the initial measurement results of the aberration measuring system, so that the tilt component and the power component are reduced. Is possible. This function enables highly accurate measurement of wavefront aberration based on high-speed position control. The measurement of the wavefront aberration of the projection optical system PL is performed not only at the time of initial adjustment and inspection of the projection optical system PL but also at the time of subsequent inspection. Since the measurement of the wavefront aberration at the time of inspection is performed by temporarily stopping the manufacture of the device, which is the original purpose of the projection exposure apparatus, quick operation is required. In this case, the easiness and quickness of the position control are very important factors.

In order to accurately measure the wavefront aberration of the projection optical system PL mounted on the projection exposure apparatus, how to deal with the influence of the wavefront aberration generated in the aberration measurement system itself becomes a problem. . The aberration measurement system includes an infinity objective lens L2, an afocal relay lens L1, a micro fly's eye lens (micro lens array) 14, a CC
Optical members such as D15 and a mirror (see FIG. 7) are used. The manufacturing error of these optical members depends on the projection optical system P
When the wavefront aberration of L is measured, it is added to the measured value. In order to minimize the influence on the measured values such as the wavefront aberration generated by the aberration measurement system itself, the tolerance of each optical member constituting the aberration measurement system is set very tight, and the projection optical system PL as the optical system to be measured is set. A method of keeping the amount of wavefront aberration generated by the aberration measurement system sufficiently small compared to the amount of wavefront aberration generated by the system, or a method of compensating the measured values by grasping in advance the effects of the wavefront aberration generated by the aberration measurement system itself in advance Can be

In the case where the test optical system is a projection optical system PL mounted on a projection exposure apparatus, it is practically impossible to suppress the amount of wavefront aberration generated by the aberration measuring system sufficiently smaller than the projection optical system PL. Close to. This is because the wavefront aberration amount remaining in the projection optical system PL of the projection exposure apparatus is originally suppressed to a very small value. On the other hand, in order to strictly set the surface accuracy of the lens components and mirror components that make up the aberration measurement system, it is necessary to improve the uniformity of the optical material (optical glass) itself, and to set the absolute value accuracy of the interferometer that measures the surface accuracy. Must be improved.

In order to improve the accuracy of the interferometer, it is necessary to improve the accuracy at the component level such as the Fizeau lens and the reference spherical mirror constituting the interferometer and to grasp the error. Stricter accuracy is also required of the polishing machine itself for improving the surface accuracy, and in some cases, a partially modified polishing technique for partially correcting the surface accuracy must be applied. By enumerating in this way, it can be seen how difficult it is to suppress the amount of wavefront aberration generated by the aberration measurement system itself sufficiently smaller than that of the projection optical system PL. Therefore, the amount of wavefront aberration generated in the aberration measurement system itself is suppressed to a certain allowable range, and the measurement value is corrected based on the error of the aberration measurement system. It is understood that it is desirable to correct the influence of the wavefront aberration and the like generated in the above.

Hereinafter, the procedure of self-calibration of the aberration measurement system will be described with reference to FIG. First, at the time of self-calibration of the aberration measurement system, the aberration measurement system is positioned at a position where an image of the square opening 10b (see FIG. 9) of the test mask TM is formed via the projection optical system PL. In this state, the illumination light from the illumination systems (1 to 9) illuminates the calibration opening 11b of the sign plate 11 via the projection optical system PL. Here, the projection optical system P
The illumination area (the image of the opening 10b) formed on the sign plate 11 via L is substantially larger than the calibration opening 11b.

In this way, the light from the calibration opening 11b passes through the infinity objective lens L2, the afocal relay lens L1, and the micro fly's eye lens (microlens array) 14 onto the light-receiving surface of the CCD 15 and enters the calibration opening 11b. A large number of images of the portion 11b are formed. With the design values, the images of the calibration opening 11b should be formed neatly on the optical axis of each microlens 14a of the micro fly's eye lens (microlens array) 14. However, the wavefront aberration of the aberration measurement system, the manufacturing error of the micro fly's eye lens (micro lens array) 14, the CCD 15
Due to the arrangement error or the like of the light receiving elements, the center of gravity of the light amount of each aperture image actually measured is shifted from the ideal position assumed in design.

Here, the generated positional deviation of each aperture image is caused only by the aberration measuring system, and is not affected by the wavefront aberration of the projection optical system PL. This is because, in the self-calibration state of FIG. 20, the projection optical system PL merely performs the function of the illumination relay optical system arranged in the optical path between the illumination system and the aberration measurement system. Therefore, the position of each opening image obtained by the self-calibration is set as each origin for measurement. Then, by measuring the wavefront aberration based on each set origin for measurement, an error such as a wavefront aberration generated by the aberration measurement system itself does not substantially affect the measurement result of the projection optical system PL. Highly accurate wavefront aberration measurement can be performed. Since the calibration opening 11b is formed on the sign plate 11 integrally attached to the aberration measurement system, the self-calibration opening is installed every time calibration is performed. No error occurs due to the displacement of the opening.

As an error generated when measuring the wavefront aberration of the optical system to be measured, an error caused by a difference between an environment at the time of actually measuring the wavefront aberration and an environment at the time of self-calibration can be considered. Specifically, there are an error caused by a change in wavelength, an error caused by a change in temperature, an error caused by a change in atmospheric pressure, and the like. All of these environmental fluctuations cause measurement errors of the aberration measurement system,
The components that are mainly affected are low-order aberrations equal to or less than the third-order aberration (up to five Seidel aberrations in geometrical optics).

Here, the error due to the wavelength variation and the error due to the atmospheric pressure variation affect the aberration measurement system. However, the amount of the error is almost as designed, and can be estimated by software. It is considered possible. Therefore, it is possible to measure an error at a predetermined pressure and a predetermined wavelength during the self-calibration, and to predict a change in the error caused by a change in the pressure and a change in the wavelength based on the measured error. Specifically, a variation between the actual pressure and wavelength at the time of measurement and the pressure and wavelength at the time of self-calibration is obtained, and based on the obtained variation and the amount of error generated at the time of self-calibration, the actual It is possible to determine the amount of error generated during measurement.

On the other hand, regarding errors caused by temperature fluctuations, errors generated under a plurality of temperature conditions during self-calibration are measured, and errors based on the temperature fluctuations are measured based on the plurality of measured errors. Can be predicted. Specifically, the variation between the actual temperature at the time of measurement and the measurement temperature closest to the actual temperature among the plurality of measurement temperatures at the time of self-calibration is obtained, Based on the generated error amount, it is possible to determine the generated error amount at the time of actual measurement by interpolation (or extrapolation).

In the self-calibration state shown in FIG. 20, the diameter of the variable aperture of the aperture stop AS arranged on the pupil of the projection optical system PL is adjusted to satisfy the condition of incoherent illumination for the calibration aperture 11b. In addition to expanding (for example, maximally) the test mask T
It is desirable to set the opening 10b of M near the optical axis AX of the projection optical system PL. Further, it is desirable to provide a diffusion optical member such as a lemon skin plate 18 in the optical path between the projection optical system PL and the sign plate 11.

However, when self-calibration has been performed in advance and it is desired to correct only errors due to fluctuations in wavelength, atmospheric pressure, and temperature, the error amount is only low-order aberration and small, so that the incoherent illumination It is not necessary to meet the conditions. When the condition of the incoherent illumination is not satisfied, no light is incident on the microlenses at the peripheral portion of the micro fly's eye lens (microlens array) 14, but the positional deviation of the image formed via the microlens at the central portion is caused. The error can be corrected based on the error. In other words, self-calibration is performed in advance to determine each origin position, measurement can be performed at any time with a certain level of measurement accuracy, and in the subsequent calibration before actual measurement, an offset may be added to each origin position. Good. As described above, various correction methods based on the self-calibration can be considered, but there is no change in correcting the influence of the wavefront aberration or the like generated in the aberration measurement system itself.

As described above, in the above-described projection exposure apparatus, the errors of the aberration measurement systems (1 to 9) are measured by self-calibration (error measurement step). The measured error is, for example, a signal processing unit 19 (FIG. 8) connected to the CCD 15.
And FIG. 16). Then, the wavefront aberration of the projection optical system PL as the test optical system is measured using the aberration measurement system (aberration measurement step), and based on the error information measured by the self-calibration, the projection optical system PL is measured.
Is corrected (correction step). Thus,
The projection optical system PL is adjusted based on the corrected wavefront aberration of the projection optical system PL (adjustment step). When adjusting the projection optical system PL, for example, the lens is finely moved, the pressure between the lenses is controlled, or an optical member for correcting aberration is inserted.

Next, the mask is illuminated by an illumination system (illumination step), and the transfer pattern formed on the mask is scanned and exposed on the photosensitive substrate using the projection optical system (exposure step), whereby the microdevice (exposure step) is obtained. Semiconductor elements, imaging elements, liquid crystal display elements, thin-film magnetic heads, etc.). Hereinafter, a method of manufacturing 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 projection exposure apparatus shown in FIG. 7 will be described with reference to a flowchart of FIG.

First, in step S301 in FIG. 21, a metal film is deposited on one lot of wafers. In the next step S302, a photoresist is applied on the metal film on the wafer of the l lot. Thereafter, in step S303, using the projection exposure apparatus shown in FIG. 7, the image of the pattern on the mask is sequentially exposed to each shot area on the wafer of the lot through the projection optical system (projection optical module). Transcribed. Thereafter, in step S304, the photoresist on the one lot of wafers is developed, and in step S305, etching is performed on the one lot of wafers using the resist pattern as a mask, thereby forming a pattern on the mask. A corresponding circuit 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 projection exposure apparatus shown in FIG. 7, a liquid crystal display element as a micro device can be obtained by forming a predetermined pattern (circuit pattern, electrode pattern, etc.) on a plate (glass substrate). .
Hereinafter, a method for manufacturing a liquid crystal display device will be described with reference to the flowchart in FIG. 22, in a pattern forming step S401, a so-called photolithography step of transferring and exposing a mask pattern to a photosensitive substrate (a glass substrate coated with a resist) using the projection exposure apparatus shown in FIG. 7 is executed. . 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,
A predetermined pattern is formed on the substrate by going through the respective steps such as an etching step and a reticle peeling step, and the process proceeds to the next color filter forming step S402.

Next, in the color filter forming step S402, three colors corresponding to R (Red), G (Green), and B (Blue)
Many sets of dots are arranged in a matrix,
Alternatively, a color filter in which a set of three stripe filters of R, G, and B are arranged in a plurality of horizontal scanning line directions is formed. Then, after the color filter forming step S402,
The cell assembling step S403 is performed. In the cell assembling step S403, a liquid crystal panel (liquid crystal cell) is assembled using the substrate having the predetermined pattern obtained in the pattern forming step S401, the color filter obtained in the color filter forming step S402, and the like. In the cell assembling step S403, for example, a liquid crystal is injected between the substrate having the predetermined pattern obtained in the pattern forming step S401 and the color filter obtained in the color filter forming step S402, and a liquid crystal panel (liquid crystal cell) is formed. ) To manufacture.

Thereafter, a module assembling step S404
Then, components such as an electric circuit and a backlight for performing a display operation of the assembled liquid crystal panel (liquid crystal cell) are attached to complete a liquid crystal display element. According to the above-described method for manufacturing a liquid crystal display device, a liquid crystal display device having an extremely fine circuit pattern can be obtained with high throughput.

In the above embodiment, 193n
ArF excimer laser light source that supplies light of wavelength m
When using an F2 laser light source that supplies light with a wavelength of 57 nm, in order to avoid light absorption by oxygen, the optical path from the light source to the photosensitive substrate and the optical path in the aberration measurement system must be an inert gas such as nitrogen or helium. Will be filled with.
In this case, the aberration measurement system should be transported, for example, in a bag or a container filled with an inert gas so that the lens surface in the aberration measurement system does not fog by contact with dirty air. Is preferred.

Further, in the above embodiment, the wavefront aberration measuring device incorporated in the projection exposure apparatus is used.
As shown in FIG. 3, for example, a wavefront aberration measuring apparatus having a dedicated stage similar to a wafer stage may be used.
In this case, the wavefront aberration measuring apparatus according to the modification shown in FIG. 23 has an illumination system having the same configuration as the illumination system of the projection exposure apparatus of FIG. 7, and a configuration similar to the wafer stage of the projection exposure apparatus of FIG. Dedicated stage SS and F
The IA system and the oblique incidence AF system are not provided. Instead of these alignment systems, the dedicated stage SS includes a first interferometer IF1 for measuring the amount of movement in the Y direction,
A pair of second interferometers IF for measuring the amount of movement in the X direction
2 and a third interferometer IF3. In the wavefront aberration measuring apparatus according to the modification shown in FIG. 23, the projection optical system PL to be mounted on the projection exposure apparatus and other appropriate optical systems to be inspected SL
Is measured.

Incidentally, the wavefront aberration measuring apparatus according to the modification shown in FIG. 23 uses an illumination system having the same configuration as the illumination system of the projection exposure apparatus shown in FIG. 7, but as shown in FIG. A wavefront aberration measuring device having a unit can also be used. In this case, in the wavefront aberration measuring apparatus according to the modification shown in FIG. 24, after the light from the light source (not shown) is propagated by the light guide 61, the opening of the test mask TM is passed through the condenser lens 62. Light up. The exit end of the light guide 61 and the condenser lens 62 are integrally supported by a support 63.

Here, the lighting units (61-63)
The test mask TM is configured to be illuminated with a numerical aperture equal to or larger than the numerical aperture on the object side of the projection optical system PL or another appropriate optical system SL to be mounted on the projection exposure apparatus. If the size of the illumination area formed by the illumination units (61 to 63) on the test mask TM is not sufficient, the support 63
Are moved two-dimensionally along the XY plane, and the projection optical system P
The wavefront aberration of L or the test optical system SL is measured.

In the above-described embodiment, the self-calibration of the aberration measurement system is performed by using the illumination system of the projection exposure apparatus and making the projection optical system PL function as an illumination relay optical system. As described above, the self-calibration can be performed using a dedicated lighting unit similar to the lighting unit of the modification shown in FIG. That is, in the modification shown in FIG. 25, after the light from the light source (not shown) is propagated by the light guide 61, the calibration opening 1
Illuminate 1b. At this time, the lighting units (61, 6)
2) is configured to illuminate the sign plate 11 with a numerical aperture equal to or larger than the numerical aperture on the object side of the aberration measurement system. Thus, similarly to the above-described embodiment, the error of the aberration measurement system can be measured.

In the modification shown in FIG. 25, the self-calibration of the aberration measurement system is performed using a dedicated illumination unit. However, as shown in FIG. 26, the illumination system of the embodiment shown in FIG. Self-calibration can also be performed using a relay optical system. That is, in the modification shown in FIG. 26, light from the illumination system having the same configuration as the illumination system of the embodiment of FIG. 7 illuminates the calibration opening 11 b of the sign plate 11 via the illumination relay optical system 71. I do. At this time, the illumination relay optical system 71 is configured to illuminate the sign plate 11 with a numerical aperture equal to or greater than the object-side numerical aperture of the aberration measurement system. Thus, similarly to the above-described embodiment, the error of the aberration measurement system can be measured.

Further, in the above-described embodiment, the image of the calibration opening 11b formed in the center of the
Although the self-calibration of the aberration measurement system is performed by forming the light beam on the light receiving surface, it is also possible to perform the self-calibration based on the spherical wave generated through the minimal pinhole as shown in FIG. it can. That is,
In the modification shown in FIG. 27, a tool 81 having a minimal pinhole formed at a position optically conjugate with the light receiving surface of the CCD 15
Position.

Therefore, in the case of the modification shown in FIG.
A predetermined gap is formed between a surface optically conjugate with the light receiving surface of D15 and the reference plane 11a of the sign plate 11. When the tool 81 is illuminated in this state, the spherical wave generated from the pinhole is transmitted through the infinity objective lens L2, the afocal relay lens L1, and the micro fly's eye lens (microlens array) 14 to the light receiving surface of the CCD 15. A large number of images (collection points) of the minimum pinhole are formed on the substrate. Thus, similarly to the above-described embodiment, the error of the aberration measurement system can be measured.

As shown in FIG. 28, a modification shown in FIG. 27 can be applied to the projection exposure apparatus shown in FIG. In this case, at the time of self-calibration of the aberration measurement system, a test mask TM in which a minimal pinhole is formed is installed. When the illumination system (1 to 9) illuminates the test mask TM in this state, the spherical wave generated from the minimal pinhole becomes the projection optical system PL, the infinity objective lens L2, the afocal relay lens L1, and the micro fly's eye lens. Through the (microlens array) 14, a large number of images (collection points) of the minimal pinholes are formed on the light receiving surface of the CCD 15. Thus, similarly to the above-described embodiment, it is possible to measure, for example, a change in an error of the aberration measurement system due to a change in the environment.

[0140]

According to the objective optical system of the present invention, the first positive lens composed of an optical material having a negative temperature coefficient of refractive index and the optical material having a positive temperature coefficient of refractive index And the second positive lens composed of an optical material having a refractive index temperature coefficient having a positive value. ) Is corrected by a positive (in a direction away from the exit pupil P) focal position change caused by a first positive lens made of an optical material having a negative refractive index temperature coefficient. This makes it possible to reduce fluctuations in optical characteristics such as focal position fluctuations when the temperature changes (for example, when used under different temperatures).

Further, according to the objective optical system of the present invention, each of the objective lens system and the relay optical system has a first positive lens made of an optical material having a negative refractive index temperature coefficient, Rate temperature coefficient includes a second positive lens made of an optical material having a positive value, so that even when a temperature change occurs only in the objective lens system or when a temperature change occurs only in the relay optical system. In addition, a negative (in a direction approaching the exit pupil P) focal position fluctuation caused by a temperature change generated by the second positive lens made of an optical material having a positive value of the refractive index temperature coefficient is corrected by a negative refractive index temperature coefficient. Can be corrected by a change in the focal position in the positive direction (in a direction away from the exit pupil P) at the time of temperature change generated by the first positive lens made of an optical material having a value. Focus on use) It is possible to reduce the optical characteristic fluctuation of location fluctuations.

According to the aberration measuring apparatus of the present invention,
As the objective optical system that uses a minute area in the image plane of the test optical system as a measurement object point, the objective optical system in which the focal position fluctuation at the time of temperature change is reduced is used. Accurate aberration measurement can be performed even when the environment changes.

Further, according to the projection exposure apparatus of the present invention,
It includes an aberration measuring device using an objective optical system with a small focal position fluctuation at the time of temperature change. This aberration measuring device measures the aberration of the projection optical system as a test optical system. (Set temperature), the aberration of the projection optical system as the test optical system which is always stable can be accurately measured.

According to the method for manufacturing an objective optical system of the present invention, it is possible to manufacture an objective optical system with a small focal position fluctuation when the environmental temperature changes.

According to the objective optical system manufacturing method of the present invention, the first positive lens made of an optical material having a negative refractive index temperature coefficient and the optical lens having a positive refractive index temperature coefficient are used. Since the design is performed using the second positive lens made of a material, the negative (exit pupil) at the time of temperature change generated in the second positive lens made of an optical material having a refractive index temperature coefficient having a positive value The focal position fluctuation in the direction (approaching P) is caused by a first positive lens made of an optical material having a negative value of the refractive index temperature coefficient. It is possible to manufacture an objective optical system that is corrected by the fluctuation.

According to the method of manufacturing the aberration measuring apparatus of the present invention, since the objective optical system in which the focal position changes little when the temperature changes is used, it is possible to accurately measure the aberration even when the environmental temperature changes. A measuring device can be manufactured.

According to the method of manufacturing the projection exposure apparatus of the present invention, the aberration of the projection optical system as the test optical system which is always stable without being influenced by the environmental temperature or the temperature change (for example, the set temperature in the clean room). A projection exposure apparatus capable of measuring with high accuracy can be manufactured.

According to the method of manufacturing a micro device of the present invention, an image of a pattern of a mask can be faithfully formed on a photosensitive substrate, so that a micro device can be manufactured with high throughput.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a lens cross section of an objective optical system according to a first embodiment.

FIG. 2 is a diagram illustrating a state in which the objective optical system according to the first embodiment is disposed in a lens barrel.

FIG. 3 is a flowchart for explaining a method of manufacturing the objective optical system according to the first embodiment and the second embodiment.

FIG. 4 is a diagram for explaining a change in a focal position when each optical member independently changes by 1 ° C. in the objective optical system according to the first embodiment.

FIG. 5 is a diagram illustrating a lens cross section of an objective optical system according to a second embodiment.

FIG. 6 is a diagram for explaining a change in a focal position when each optical member independently changes by 1 ° C. in the objective optical system according to the second embodiment.

FIG. 7 is a diagram schematically showing a configuration of a projection exposure apparatus including a wavefront aberration measuring apparatus according to the embodiment.

FIG. 8 is a diagram schematically illustrating a main configuration of a wavefront aberration measuring apparatus according to an embodiment, and is a diagram illustrating a state where an aberration measuring system is developed along an optical axis thereof.

FIG. 9 is a diagram schematically showing a configuration of a test mask installed on a mask stage when measuring a wavefront aberration of a projection optical system.

FIG. 10 is a diagram schematically showing a configuration of a sign plate integrally attached to the aberration measurement system.

FIG. 11 is a diagram schematically showing a configuration of a micro fly's eye lens as a wavefront splitting element in the aberration measurement system.

FIG. 12 is a diagram illustrating scattering characteristics when a parallel light beam enters a lemon skin plate.

FIG. 13 compares the luminance distribution in the illumination NA of the light beam incident on the test mask when the lemon skin plate is not installed and the luminance distribution in the illumination NA of the light beam incident on the test mask when the lemon skin plate is installed. FIG.

FIG. 14 is a diagram showing a transmittance distribution of an inverse normal distribution shape given to a density filter.

FIG. 15 is a diagram showing a state in which the secondary light source is limited to a ring shape through a ring-shaped aperture stop to make luminance characteristics of an illumination light flux deteriorated by a lemon skin plate substantially uniform.

FIG. 16 is a diagram showing a state in which a number of imaging optical systems independent of each other exist for each micro lens of a micro fly's eye lens of an aberration measurement system.

FIG. 17 is a diagram showing a state in which an image of the opening of the test mask is formed at the center of the calibration opening of the sign plate.

FIG. 18 is a flowchart for explaining a method of manufacturing the wavefront aberration measuring device.

FIG. 19 is a flowchart illustrating a method of manufacturing a projection exposure apparatus.

FIG. 20 is a diagram illustrating a procedure of self-calibration of the aberration measurement system according to the embodiment.

FIG. 21 is a flowchart showing a method for manufacturing a semiconductor device as a micro device.

FIG. 22 is a flowchart showing a method for manufacturing a liquid crystal display element as a micro device.

FIG. 23 is a diagram illustrating a wavefront aberration measuring apparatus having a dedicated stage similar to the wafer stage of FIG. 7;

FIG. 24 is a diagram showing a wavefront aberration measurement device having a dedicated illumination unit.

FIG. 25 is a diagram showing a modification in which self-calibration is performed using a dedicated lighting unit similar to the lighting unit shown in FIG. 24.

26 is a diagram illustrating a modification in which self-calibration is performed using the illumination system and the illumination relay optical system of the embodiment of FIG. 7;

FIG. 27 is a diagram illustrating a modification in which self-calibration is performed based on a spherical wave generated via a minimum pinhole.

FIG. 28 is a diagram showing a modification in which the modification shown in FIG. 27 is applied to the projection exposure apparatus of FIG. 7 to perform self-calibration.

[Explanation of symbols]

OL1, OL2: Objective optical system, L1: Afocal relay lens, L2: Infinity objective lens, P: Exit pupil, O ...
Object point, LM ... Barrel, 1 ... Light source, 2 ... Beam shaping optical system,
3 ... coherence reducing unit, 4,7 ... fly-eye lens, 5 ... vibrating mirror, 6 ... relay optical system, 8 ... aperture stop, 9 ... condenser optical system, 11 ... sign plate, 14 ... micro fly-eye lens, 15 ... CCD, 16 ... lemon skin plate, 1
7: density filter, 19: signal processing unit, M: mask, MS: mask stage, TM: test mask, PL
... Projection optical system, W: Wafer, WS: Wafer stage.

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Claims (14)

[Claims] 1. A first positive lens made of an optical material having a negative refractive index temperature coefficient, and a second positive lens made of an optical material having a positive refractive index temperature coefficient. And an objective optical system comprising: 2. The focal length of the entire objective optical system is f,
2. The objective optical system according to claim 1, wherein the following condition is satisfied when the focal length of the entire system when the temperature of the entire objective optical system changes by ΔT (° C.) is f ₁ . | (F ₁ -f) / f / ΔT | <10 ^-4 (1 / ° C) 3. An objective lens system for converting light from an object point into light in a predetermined state, and a relay optical system for relaying light from the objective lens system, wherein the objective optical system and the relay optical system Includes a first positive lens made of an optical material having a negative refractive index temperature coefficient, and a second positive lens made of an optical material having a positive refractive index temperature coefficient. An objective optical system, characterized in that: 4. The focal length of the entire objective optical system is f,
The focal length of the entire system when only the objective lens system changes in temperature by ΔT (° C.) is fo, and only the relay optical system is ΔT
4. The objective optical system according to claim 3, wherein the following condition is satisfied when the focal length of the entire system when the temperature changes by (° C.) is fr. | ((Fo−f) / f) / ΔT | <10 ⁻⁴ (1 / ° C.) | ((fr−f) / f) / ΔT | <10 ⁻⁴ (1 / ° C.) 5. The camera according to claim 1, further comprising a holding member that holds the first positive lens and the second positive lens, wherein the holding member includes:
The linear expansion coefficient of the first positive lens is smaller than that of the second positive lens, and the linear expansion coefficient of the second positive lens is larger than the linear expansion coefficient of the second positive lens. Objective optics. 6. The first positive lens and the second positive lens transmit light having a wavelength of 300 nm or less so as to impart a predetermined optical effect to light having a wavelength of 300 nm or less. The objective optical system according to any one of claims 1 to 5, wherein 7. The apparatus according to claim 1, wherein a minute area in the imaging plane is set as a measurement object point in order to measure an aberration related to the imaging plane of the optical system to be measured. An aberration measuring apparatus, comprising: an objective optical system; and photoelectric detection means for detecting light from the measurement object point via the objective optical system. 8. A projection exposure apparatus including a projection optical system for forming a pattern image of a mask on a photosensitive substrate, the projection exposure apparatus including the aberration measurement apparatus according to claim 7, wherein the aberration measurement apparatus covers the projection optical system. A projection exposure apparatus, wherein an aberration of the projection optical system is measured as an optical inspection system. 9. A first design step of designing an objective optical system having a predetermined performance at a reference temperature, and designing the objective optical system to maintain the predetermined performance in a state shifted from the reference temperature by a predetermined temperature. 2
A method for manufacturing an objective optical system, comprising: a designing step. 10. The second design step comprises a first positive lens made of an optical material having a negative refractive index temperature coefficient and an optical material having a positive refractive index temperature coefficient. 10. The method for manufacturing an objective optical system according to claim 9, wherein the design is performed using a second positive lens. 11. A step of preparing an objective optical system manufactured by the method according to claim 9 or 10; and measuring an aberration of the optical system to be measured with respect to the image plane of the objective optical system. A step of arranging photoelectric detection means at a position where light from the minute area is emitted through the objective optical system. 12. A method of manufacturing a projection exposure apparatus including a projection optical system for forming a pattern image of a mask on a photosensitive substrate, wherein: a step of preparing an aberration measuring apparatus manufactured by the method according to claim 11; Arranging the aberration measuring device at a position where the aberration of the projection optical system is measured using the projection optical system as a test optical system. 13. An exposure step of exposing a mask pattern on a photosensitive substrate using the projection exposure apparatus according to claim 8, and a developing step of developing the photosensitive substrate exposed in the exposure step. A method for manufacturing a micro device, comprising: 14. An exposure step of exposing a pattern of a mask on a photosensitive substrate using a projection exposure apparatus manufactured by the method according to claim 12, and developing the photosensitive substrate exposed in the exposure step. And a developing step.