JP2002323405A - Optical characteristic measurement method and device and exposing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure optical characteristics of an optical system to be inspected. SOLUTION: A spot is photographed on a photographing surface 95S where the half width of a light intensity distribution of a spot image becomes smaller than an imaging surface CP of a wavefront splitting optical system constituted of a plurality of condensing elements with a small Fresnel number so that a cross-talk quantity between spot images is reduced in the photographed result. Based on the photographed result of the spots with reduced cross talk, the spot image position is accurately obtained and the optical characteristics of the optical system to be inspected is calculated using the accurately obtained spot image position. As the results, the optical characteristics of an optical system to be inspected can be accurately measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical characteristic measuring method, an optical characteristic measuring apparatus, and an exposure apparatus, and more particularly, to an optical characteristic measuring method and an optical characteristic measuring apparatus for measuring an optical characteristic of a test optical system. And an exposure apparatus including the optical property measuring apparatus, an optical system whose optical properties are measured by the optical property measuring apparatus, and an optical property adjustment apparatus that adjusts the optical properties based on the optical properties measured by the optical property measuring apparatus. The present invention relates to a method, a method for manufacturing the exposure apparatus, and a semiconductor device manufactured using the exposure apparatus.

[0002]

2. Description of the Related Art Conventionally, in a lithography process for manufacturing a semiconductor device, a liquid crystal display device, or the like, a pattern (hereinafter, referred to as a “reticle pattern”) formed on a mask or a reticle (hereinafter, collectively referred to as a “mask”). Substrate) such as a wafer or a glass plate coated with a resist or the like via a projection optical system (hereinafter, collectively referred to as “substrate” as appropriate)
An exposure apparatus for transferring the image on the top is used. As such an exposure apparatus, a stationary exposure type exposure apparatus such as a so-called stepper and a scanning exposure type exposure apparatus such as a so-called scanning stepper are mainly used.

In such an exposure apparatus, it is necessary to faithfully project a pattern formed on a reticle onto a substrate with high resolution. For this reason, the projection optical system is designed to have good optical characteristics with various aberrations sufficiently suppressed.

[0004] However, it is difficult to manufacture a projection optical system completely as designed, and various aberrations due to various factors remain in an actually manufactured projection optical system.
Therefore, the optical characteristics of the actually manufactured projection optical system are as follows:
This is different from the designed optical characteristics.

Therefore, various techniques have been proposed for measuring optical characteristics such as aberrations of a test optical system such as an actually manufactured projection optical system. Among such various proposed technologies, a spherical wave generated by using a pinhole is incident on an optical system to be measured, and the light that has passed through the optical system to be tested is converted into parallel light, and then split into wavefronts. A Shack-Hartmann-based wavefront aberration measurement technique that forms a spot image for each of the divided wavefronts and measures the wavefront aberration of the optical system to be measured based on the formation position of the spot image for each divided wavefront has attracted attention.

A wavefront aberration measuring device (or a wavefront measuring device) adopting the Shack-Hartmann method is, for example, a wavefront splitting device for splitting incident light into wavefronts and forming a spot image for each split wavefront. By employing a microlens array in which a large number of microlenses (microlenses) as light-collecting elements are arranged along a two-dimensional plane parallel to the above, the configuration can be simplified.
Then, a large number of spot images formed by the microlens array are picked up by an image pickup device such as a CCD, and the center of gravity of the picked-up waveform of each spot image is obtained by the centroid method. The position of the spot image is detected by obtaining the position by a correlation method.

[0007] The position of each spot image detected in this manner represents a local inclination of the wavefront of the light incident on each microlens. Therefore, by performing an operation such as integrating the local inclination of the wavefront, the wavefront aberration is obtained by two-dimensionally reconstructing the wavefront shape of the test optical system.

[0008]

A wavefront aberration measuring apparatus using a microlens array as described above can capture a large number of spot images formed by each of the divided wavefronts at once, so that the wavefront aberration can be quickly reduced. It is very excellent from the viewpoint that it can be measured.

The measurement of the wavefront aberration is based on the premise that even if the wavefront is inclined in each divided wavefront, the inclination can be regarded as a linear inclination.
Therefore, in order to accurately measure the wavefront aberration, it is preferable to divide the wavefront as finely as possible. In order to accurately measure the wavefront aberration, it is preferable to increase the focal length of each microlens of the microlens array and increase the displacement of the spot position with respect to the tilt amount of the divided wavefront.

However, if the division of the wavefront is made fine, the arrangement interval of each spot image formed by each microlens of the microlens array becomes narrow. As a result, in the entire image in which a large number of spots to be imaged are formed, the position of the spot image by a certain microlens is
The influence of the spot image by the micro lens around the micro lens appears. In other words, when the division of the wavefront is made fine, so-called crosstalk easily occurs between spot images formed by the microlenses (particularly, between adjacent spot images).

When the focal length of each microlens is increased and the displacement of the spot position with respect to the inclination of the divided wavefront is increased, the diameter of the spot image formed by each microlens becomes smaller than the focal length of each microlens. If the difference between the two divided wavefronts adjacent to each other is large, the interval between spot images corresponding to these divided wavefronts is larger than when the focal length of each microlens is shorter. Narrows. That is, even when the focal length of each microlens is increased, so-called crosstalk easily occurs between spot images formed by the microlenses (particularly, between adjacent spot images).

When crosstalk occurs as described above, the spot image formed in each spot image forming area is deformed from the original spot image shape,
Such a deformed spot image is captured.
For this reason, when the position information of each spot image is detected from the imaging result in the formation region of each spot image, the detected position information includes a detection error accompanying the deformation of the spot image due to crosstalk. Such a decrease in the detection accuracy of the spot image position causes a decrease in the measurement accuracy of the measurement result of the wavefront aberration.

However, in a wavefront aberration measuring apparatus using a microlens array or the like, in order to improve the measurement accuracy, it is essential to make the division of the wavefront fine and to increase the focal length of the light-collecting element. is there. For this reason, a new technique for reducing the crosstalk between the spot images as described above is currently demanded.

The present invention has been made under such circumstances, and a first object of the present invention is to provide an optical characteristic measuring method and an optical characteristic measuring apparatus capable of accurately measuring the optical characteristics of a test optical system. Is to provide.

It is a second object of the present invention to provide an exposure apparatus capable of transferring a predetermined pattern onto a substrate with high accuracy.

A third object of the present invention is to provide an optical system whose optical characteristics are measured with high accuracy.

A fourth object of the present invention is to provide an optical system whose optical characteristics are adjusted with high accuracy.

A fifth object of the present invention is to provide a semiconductor device in which a fine pattern is formed with high accuracy.

[0019]

Means for Solving the Problems The present inventor has developed a shack.
The following findings were obtained as a result of research and development on the measurement of optical characteristics by the Hartmann method.

In the optical characteristic measurement by the Shack-Hartmann method, a light-collecting element having a small aperture such as a lens element in a microlens array is used, and the focal length of the light-collecting element is increased to improve measurement accuracy. become. As a result, the condensing element has a Fresnel number N defined by N = a ² / (f · λ) (1) that is much smaller than that of a normal optical lens or the like. Here, the parameter a is a distance from the geometric center (centroid) of the aperture to the farthest point in the aperture of the light-collecting element, and corresponds to the radius of the circular aperture in the case of a circular aperture. It is. The parameter f is the focal length of the light-collecting element, and the parameter λ is the wavelength of light incident on the light-collecting element, that is, the light passing through the optical system to be measured.

Here, the "focal point" means a point at which all the phases of the light beams passing through the respective points of the aperture of the light-collecting element coincide with each other or the variance of the phase is minimized. Further, the “focal length” means a distance between a light-collecting element (more precisely, a surface that is effectively changed when a plane wave is incident on the light-collecting element) and the focal point. In this specification, the terms “focal point” and “focal length” are used in the above sense.

It is known that the change in the light intensity distribution of the spot in the vicinity of the optical image plane due to the light-collecting element whose Fresnel number N is less than 10 is significantly different from that of the light-collecting element having a large Fresnel number N. (Y. Li and E. W
olf, ： J. Opt. Soc. Am. A, Vol. 1, No. 8, 1984, 80
1-808 etc.). That is, in the case of an image formed by a light-collecting element having a small Fresnel number N, the diffusing effect due to diffraction by the aperture antagonizes the light-collecting effect of the light-collecting element. The asymmetry of the change in the light intensity distribution of the spot becomes significant. That is, since the diffusion effect by diffraction is small on the front side near the opening, the peak intensity of the spot is large and the spot diameter is small. On the other hand, on the rear side, the peak intensity of the spot is small and the spot diameter is large. Then, the position where the spot peak intensity is maximum and the spot diameter is minimum exists at a position as far away from the image plane as possible to the light-collecting element so that the imaging plane can be actually positioned, or the spot peak on the image plane The position where the peak intensity becomes larger than the intensity and the spot diameter becomes smaller than the spot diameter on the image plane exists at a position as far away from the image plane as possible to the light-collecting element so that the imaging plane can be actually positioned. .

The present invention has been made based on such findings.

That is, the optical characteristic measuring method of the present invention
An optical property measuring method for measuring an optical property of a test optical system (PL), wherein a spot forming step of forming a spot for each divided wavefront obtained by dividing a light passing through the test optical system into a wavefront; The full width at half maximum of each light intensity distribution is less than the full width at half maximum of each light intensity distribution of the spot on the imaging plane of the spot determined when the light passing through the test optical system is split into wavefronts. A spot imaging step of imaging the spot; a position information calculating step of calculating position information of each of the spots based on an imaging result in the spot imaging step; and an inspection using the calculated position information. An optical characteristic calculating step of calculating an optical characteristic of the optical system.

According to this, when the plurality of spots formed in the spot forming step are spot imaging steps, the full width at half maximum of each light intensity distribution of the spot is less than the full width at half maximum of each light intensity distribution of the spot on the image plane. An image is taken at the imaging surface position where The diameter of each spot image in the imaging result of this imaging is smaller than the diameter of each spot image captured when the imaging surface is arranged on the conventional image plane. Therefore, the amount of light originating from other spots entering the formation area of each spot is smaller than in the case of the imaging result on the image plane, and the amount of crosstalk between spot images is also smaller.

Subsequently, in the position information calculating step, the center of gravity and the like of the light intensity distribution of each spot image are calculated based on the plurality of picked-up spot images, thereby lowering the detection accuracy due to crosstalk between the spot images. And the position information of the spot image is detected. Then, in the optical characteristic calculation step, the optical characteristic of the test optical system is calculated based on the position information calculated in the position information calculation step. Therefore, the optical characteristics of the test optical system can be accurately measured.

In the optical characteristic measuring method according to the present invention, the Fresnel number of the light condensing element for dividing the light passing through the optical system to be subjected to the wavefront is set to 4.86 or less, and the position of the imaging plane is set to the light intensity distribution of the spot. Can be set to a position where 95% or less of the full width at half maximum of each light intensity distribution of the spot on the image plane of the light condensing element.

Further, in the optical characteristic measuring method according to the present invention, a distance between a point farthest from the center of the aperture in the aperture of the light condensing element for dividing the light passing through the test optical system into a wavefront is a,
The focal length of the light-collecting element is f, the wavelength of light passing through the test optical system is λ, the Fresnel number is N, and the parameter u _N is u _N = (2πa ² / (f · λ)) · (( -d / f) / (1- (d / f))), the imaging surface position is defined as I (u _N ) = (1+ (u _N / 2πN)) ² · (2 / ( u _N / 2) ² ) ・ (1-cos (u _N / 2))
A distance d that satisfies> 1.05 can be a position closer to the light-collecting element from the position of the image plane.

Here, the position of the imaging plane is set to a position closer to the light-collecting element from the position of the image plane by a distance d that further satisfies d <f ² · λ / (2a ² + f · λ). be able to.

Further, in the optical characteristic measuring method according to the present invention, in the opening of the light-collecting element, a is a distance from the center of the opening to the farthest point, f is a focal length of the light-collecting element, Assuming that the wavelength of light passing through the optical system is λ, the imaging surface position is separated from the image surface by a distance less than a distance D defined by D = f ² · λ / (2a ² + f · λ). Position.

The optical characteristic measuring apparatus of the present invention is an optical characteristic measuring apparatus for measuring the optical characteristic of a test optical system (PL), and has a plurality of light collecting elements (94a). A wavefront splitting optical system (94) that splits the light passing through the test optical system into wavefronts according to the arrangement of the elements and forms spots for each split wavefront; and a full width at half maximum of each light intensity distribution of the spots. An image pickup device (95), wherein an image pickup surface is disposed at a position on the image plane of the light-collecting element that is smaller than a full width at half maximum of each light intensity distribution of the spot.

According to this, when the spot formed by the wavefront splitting optical system is such that the full width at half maximum of each light intensity distribution of the spot is less than the full width at half maximum of each light intensity distribution of the spot on the image plane of the light condensing element. An image is taken by an image pickup device having an image pickup surface arranged at a position as shown below. The diameter of each spot image in the imaging result of this imaging device is smaller than the diameter of each spot image captured when the imaging surface is arranged on the conventional image plane, and other spot images that enter the formation area of each spot are formed. The amount of light originating from the spot is smaller than in the case of the imaging result on the image plane, and the amount of crosstalk between spot images is also smaller. Therefore, the position information of each spot image is detected based on the image pickup result by the image pickup device, and the optical characteristics are obtained using the detected position information, so that the optical characteristics of the optical system to be measured can be accurately measured. it can.

In the optical characteristic measuring apparatus of the present invention, each of the light-collecting elements is a lens element (94a), and the wavefront dividing optical system is a microlens array (94) in which the lens elements are two-dimensionally arranged. It can be configured to include.

Here, the Fresnel number of the light-collecting element is set to 4.
86 or less, and the imaging surface is arranged at a position where the full width at half maximum of each light intensity distribution of the spot is 95% or less of the full width at half maximum of each light intensity distribution of the spot on the image plane of the light-collecting element. Configuration.

In the optical characteristic measuring apparatus of the present invention, a is a distance from the center of the opening to the farthest point in the opening of the light-collecting element, f is a focal length of the light-collecting element, Assuming that the wavelength of light passing through the optical system is λ and the Fresnel number is N, the parameter u _N is u _N = (2πa ² / (f · λ)) · ((− d / f) / (1- (d / f) ))), The imaging surface is defined as I (u _N ) = (1+ (u _N / 2πN)) ² · (2 / (u _N / 2) ² ) · (1-cos (u _N / 2))
It can be arranged at a position close to the light-collecting element from the position of the image plane by a distance d satisfying> 1.05.

In this case, the imaging surface is arranged at a position closer to the light-collecting element from the position of the image surface by a distance d that further satisfies d <f ² · λ / (2a ² + f · λ). It can be configured.

In the optical characteristic measuring apparatus according to the present invention, a is a distance from the center of the opening to the farthest point in the opening of the light-collecting element, f is a focal length of the light-collecting element, When the wavelength of light passing through the optical system is λ, the imaging surface is separated from the image surface by a distance less than a distance D defined by D = f ² · λ / (2a ² + f · λ). Position.

Further, in the optical characteristic measuring apparatus according to the present invention, a position information calculating device (36) for calculating position information of the spot image based on an image pickup result by the image pickup device; And an optical characteristic calculation device (37) for calculating the optical characteristics of the test optical system.

The exposure apparatus of the present invention is an exposure apparatus for transferring a predetermined pattern onto the substrate by irradiating the substrate (W) with exposure light, and is arranged on an optical path of the exposure light. Exposure apparatus main body having projection optical system (60)
And an optical characteristic measuring device (70) of the present invention wherein the projection optical system is a test optical system.

The optical system of the present invention is an optical system whose optical characteristics have been measured using the optical characteristic measuring device of the present invention.

An optical characteristic adjusting method according to the present invention is an optical characteristic adjusting method for adjusting the optical characteristic of an optical system (PL), wherein the optical characteristic of the optical system is measured using the optical characteristic measuring apparatus of the present invention. An optical property measuring step of measuring the optical properties of the optical system based on the measurement result in the optical property measuring step.

Further, the method of manufacturing an exposure apparatus of the present invention is a method of manufacturing an exposure apparatus which irradiates a substrate (W) with exposure light to transfer a predetermined pattern onto the substrate.
Preparing an exposure apparatus main body (60) having a projection optical system (PL) arranged on the optical path of the exposure light; and an optical characteristic measuring apparatus (70) of the present invention using the projection optical system as a test optical system. A) measuring the optical characteristics of the projection optical system using the optical characteristic measurement device; and measuring the optical characteristics based on the measurement results in the optical characteristics measurement step of the projection optical system. And an optical characteristic adjusting step of adjusting the optical characteristics of the system.

The semiconductor device of the present invention is a semiconductor device manufactured using the exposure apparatus of the present invention.

[0044]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a schematic configuration of an exposure apparatus 100 according to an embodiment of the present invention. This exposure apparatus 1
Reference numeral 00 denotes a step-and-scan projection exposure apparatus. The exposure apparatus 100 includes an exposure apparatus main body 60.
And a wavefront aberration measuring device 70 as an optical characteristic measuring device.

The exposure apparatus main body 60 includes an illumination system 10, a reticle stage RST for holding a reticle R, a projection optical system PL as a test optical system, a wafer stage WST on which a wafer W as a substrate is mounted, and an alignment system AS. ,
A stage control system 19 for controlling the positions and orientations of the reticle stage RST and the wafer stage WST, and a main control system 20 for controlling the entire apparatus are provided.

The illumination system 10 includes an illuminance uniforming optical system including a light source and a fly-eye lens, a relay lens, a variable ND
It is configured to include a filter, a reticle blind, a dichroic mirror and the like (all not shown). The configuration of such an illumination system is described in, for example, Japanese Patent Application Laid-Open No. H10-1124.
No. 33 discloses this. In the illumination system 10, a slit-shaped illumination area defined by a reticle blind on a reticle R on which a circuit pattern or the like is drawn is illuminated with illumination light I.
L illuminates with substantially uniform illuminance.

A reticle R is fixed on the reticle stage RST by, for example, vacuum suction. Here, reticle stage RST is driven by a reticle stage drive unit (not shown) composed of a two-dimensional linear actuator to position reticle R, so that the optical axis of illumination system 10 (coincides with optical axis AX of projection optical system PL described later). And can be driven at a scanning speed designated in a predetermined scanning direction (here, Y direction). Further, in the present embodiment, the above 2
Since the dimensional linear actuator also includes a Z drive actuator, it can be minutely driven in the Z direction.

The position of the reticle stage RST in the stage movement plane is constantly detected by a reticle laser interferometer (hereinafter, referred to as “reticle interferometer”) 16 through a movable mirror 15 at a resolution of, for example, about 0.5 to 1 nm. Is done. The position information (or speed information) of the reticle stage RST from the reticle interferometer 16 is sent to the main control system 20 via the stage control system 19, and based on this position information (or speed information), the main control system 20 The reticle stage RST is driven via the stage control system 19 and a reticle stage driving unit (not shown).

Since the initial position of the reticle stage RST is determined so that the reticle R is accurately positioned at a predetermined reference position by a reticle alignment system (not shown), the position of the movable mirror 15 is changed to the reticle interferometer 16. This means that the position of the reticle R has been measured with sufficiently high accuracy.

The projection optical system PL is disposed below the reticle stage RST in FIG. 1, and the direction of the optical axis AX is the Z-axis direction. The projection optical system PL is, for example, a double-sided telecentric reduction system, and includes a plurality of lens elements (not shown) having a common optical axis AX in the Z-axis direction. Further, this projection optical system P
As L, the projection magnification β is, for example, １ ／, ５, 1 /
6 and the like are used. Therefore, when the illumination area on the reticle R is illuminated by the illumination light (exposure light) IL as described above, the pattern formed on the reticle R is reduced by the projection optical system PL at the projection magnification β. The image (partially inverted image) is projected and transferred to a slit-shaped projection area on the wafer W having a surface coated with a resist (photosensitive agent).

In the present embodiment, specific lens elements (for example, five predetermined lens elements) among the above-mentioned plurality of lens elements can be independently moved. The movement of the lens element is performed by driving elements such as three piezo elements provided for each specific lens, which support a lens supporting member that supports the specific lens element and are connected to the lens barrel. I have. That is, the specific lens element can be independently moved in parallel along the optical axis AX according to the displacement amount of each drive element, and a desired inclination can be given to a plane perpendicular to the optical axis AX. Can also be. Then, the drive instruction signal given to these drive elements is controlled by an imaging characteristic correction controller 6 as a wavefront deforming device based on a command MCD from the main control system 20.
5, whereby the amount of displacement of each drive element is controlled.

In the thus configured projection optical system PL,
By controlling the movement of the lens element via the imaging characteristic correction controller 65 by the main control system 20, optical characteristics such as distortion, curvature of field, astigmatism, coma, and spherical aberration can be adjusted.

The wafer stage WST is arranged on a base (not shown) below the projection optical system PL in FIG. 1, and a wafer holder 2 is mounted on the wafer stage WST.
5 is placed. The wafer W is fixed on the wafer holder 25 by, for example, vacuum suction. The wafer holder 25 can be tilted in an arbitrary direction with respect to a plane orthogonal to the optical axis of the projection optical system PL by a driving unit (not shown), and can be finely moved in the optical axis AX direction (Z direction) of the projection optical system PL. ing. Further, the wafer holder 25 can also perform a minute rotation operation around the optical axis AX.

Further, a bracket structure is formed on the + Y direction side of wafer stage WST so that a wavefront sensor 90 described later can be attached and detached.

The wafer stage WST moves not only in the scanning direction (Y direction) but also in a direction perpendicular to the scanning direction so that a plurality of shot areas on the wafer W can be positioned in an exposure area conjugate with the illumination area. It is configured to be movable also in the direction (X direction), and repeats an operation of scanning (scanning) exposing each shot area on the wafer W and an operation of moving to an exposure start position of the next shot. Perform a scan operation. This wafer stage WST
Are XY by the wafer stage drive unit 24 including a motor and the like.
It is driven in a two-dimensional direction.

The position of the wafer stage WST in the XY plane is adjusted by a wafer laser interferometer (hereinafter, referred to as “wafer interferometer”) 18 via a movable mirror 17 to, for example, 0.5 mm.
It is always detected with a resolution of about 1 nm. The position information (or speed information) of wafer stage WST is sent to main control system 20 via stage control system 19,
Controls the drive of wafer stage WST via stage control system 19 and wafer stage drive unit 24 based on this position information (or speed information).

The alignment system AS includes a projection optical system P
In this embodiment, an off-axis microscope is used, which is arranged on the side surface of the wafer L and includes an imaging alignment sensor that observes a street line and a position detection mark (fine alignment mark) formed on the wafer W. I have. The detailed configuration of the alignment system AS is disclosed in, for example, Japanese Patent Application Laid-Open No. 9-219354. The observation result by the alignment system AS is supplied to the main control system 20.

Further, the apparatus shown in FIG. 1 has an oblique incident light type focus detection system (focal point) for detecting the position in the Z direction (optical axis AX direction) inside and near the exposure area on the surface of the wafer W. A multipoint focus position detection system (21, 22), which is one of the detection systems, is provided. The multi-point focus position detection system (21, 22) includes an irradiation optical system 21 including an optical fiber bundle, a condenser lens, a pattern forming plate, a lens, a mirror, and an irradiation objective lens (all not shown).
And a light receiving optical system 22 including a light collecting objective lens, a rotational direction vibration plate, an image forming lens, a light receiving slit plate, and a light receiving device (all not shown) having a large number of photo sensors. This multipoint focus position detection system (21,
For the detailed configuration of 22), see, for example, JP-A-6-2
83403. The detection result by the multipoint focus position detection system (21, 22) is supplied to the stage control system 19.

The wavefront aberration measuring device 70 comprises a wavefront sensor 90 and a wavefront data processing device 80.

As shown in FIG. 2, the wavefront sensor 90 includes a sign board 91, a measuring optical system 99, a CCD element 95 as an image pickup device, and a housing member 97 for housing the measuring optical system 99 and the CCD element 95. It has.

The marking plate 91 is made of, for example, a glass substrate, and is arranged at the same height position (Z direction position) as the surface of the wafer W fixed to the wafer holder 25 so as to be orthogonal to the optical axis AX1. (See FIG. 1). This sign board 91
As shown in FIG. 3, an opening 91a is formed in the center of the surface of the surface. In addition, three or more sets (4 in FIG. 3) are provided around the opening 91a on the surface of the sign board 91.
Set) two-dimensional position detection mark 91b is formed. In the present embodiment, as the two-dimensional position detection mark 91b, a combination of a line and space mark 91c formed along the X direction and a line and space mark 91d formed along the Y direction is employed. ing. Note that the line and space marks 91c, 91
d can be observed by the above-described alignment system AS. The surface of the sign plate 91 except for the opening 91a and the two-dimensional position detection mark 91b is subjected to reflection surface processing. Such reflection surface processing is performed, for example, by depositing chromium (Cr) on a glass substrate.

Returning to FIG. 2, the measuring optical system 99 includes a collimator lens 92 and a lens 93 as first-stage lens elements.
a and a lens 93b, and a micro lens array 94 as a wavefront splitting element, and are arranged on the optical axis AX1 in this order.
In addition, the measurement optical system 99 further includes mirrors 96a, 96b, and 96c for setting an optical path of light incident on the wavefront sensor 90.

The collimator lens 92 has an opening 91a.
The light incident through the light is converted into parallel light.

The micro lens array 94 shown in FIG.
As shown generally in (A) and (B), a large number of square micros having a positive refractive power in a matrix, having a focal length of f, and having a side length of PH in plan view. Lens 9
4a is densely arranged. Here, the optical axes of the microlenses 94a are substantially parallel to each other.
FIGS. 4A and 4B show an example in which the microlenses 94a are arranged in a 5 × 5 matrix at an arrangement pitch PT. The micro lens 94a is not limited to a square shape but may be a rectangular shape, and the micro lenses 94a may not all have the same shape. The arrangement of the micro lenses 94a in the micro lens array 94 may be an irregular pitch arrangement or an oblique arrangement.

The microlens array 94 is formed by etching a parallel flat glass plate. The microlens array 94 forms a pinhole image by the projection optical system PL in the opening 91a at a different position for each microlens 94a that receives light via the relay lens system 93.

Returning to FIG. 2, the CCD 95 has an image forming plane CP on which an image at the aperture 91a is formed by each micro lens 94a of the micro lens array 94, that is, a surface on which the aperture 91a is formed in the wavefront aberration measuring optical system. It has a light receiving surface 95S at a Y position separated from the conjugate plane by the distance d toward the microlens array 94, and captures a large number of spot images formed on the light receiving surface 95. Where the distance d
Is set to satisfy the conditions represented by the following equations (2) and (3).

D <f ² · λ / (2a ² + f · λ) (2) I (u _N ) = (1+ (u _N / 2πN)) ² · (2 / (u _N / 2) ² ) · (1-cos (u _N /2))>1.05 (3) where a = PT / 2 ^1/2 ... (4) u _N = (2πa ² / (f · λ)) · (( -d / f) / (1- (d / f)))… (5)

Here, the expression (2) is a condition relating to the influence of defocus. Fresnel number N is as small as 5 or less,
When the diameter a of the micro lens 94a is sufficiently smaller than the focal length f (a≪f), the micro lens 94a is separated from the conjugate plane by a defocus amount D defined by the following equation (6). , The phase difference of light passing through each point in the opening of the microlens 94a on the imaging surface 95S becomes λ / 4.

D = f ² · λ / (2a ² + f · λ) (6)

As a result, when the distance d is equal to or more than the defocus amount D, the spot image on the imaging surface 95S is blurred.
As the light intensity of the spot image decreases, the spot image bleeds to the area of the adjacent spot image, and crosstalk between the spot images increases. For this reason,
In the present embodiment, the condition that the distance d is smaller than the defocus amount D (d <D), that is, the condition of Expression (2) is adopted to prevent the light intensity of the spot image from decreasing and the crosstalk from increasing. .

Equation (3) is a condition relating to the diameter of the spot image. By arranging the imaging surface 95S at a distance d from the image plane CP that satisfies the condition of the expression (3), the full width at half maximum of 95% or less of the full width at half maximum (FWHM) in the light intensity distribution of the spot image on the image plane CP can be reduced. It is possible to capture a spot image having the light intensity distribution. As a result, the diameter of the spot image in the imaging result can be reduced, and the amount of crosstalk between the spot images can be reduced. The position satisfying the condition of the expression (3) is always on the microlens array 94 side with respect to the image plane CP.

The result of imaging by the CCD 95 is supplied to the wavefront data processing device 80 as imaging data IMD.

The housing member 97 has a support member (not shown) for supporting the collimator lens 92, the relay lens system 93, the micro lens array 94, and the CCD 95, respectively. The mirrors 96a, 96
b and 96c are attached to the inner surface of the storage member 97. Further, the outer shape of the storage member 97 is shaped to fit with the bracket structure of the wafer stage WST described above, and is detachable from the wafer stage WST.

The wavefront data processing device 80 includes a main control device 30 and a storage device 40, as shown in FIG. The main controller 30 controls (a) the entire operation of the wavefront data processor 80 and supplies the wavefront measurement result data WFA to the main control system 20;
(B) an imaging data collection device 33 that collects imaging data IMD from the wavefront sensor 90; and (c) a position information device 36 that calculates position information of a spot image based on the imaging data.
And (d) a wavefront aberration calculator 37 for calculating the wavefront aberration of the projection optical system PL based on the spot image position calculated by the position information calculator 36.

The storage device 40 includes (a) an image data storage area 41 for storing image data, (b) a position information storage area 42 for storing position information of a spot image,
(E) Wavefront aberration storage area 43 for storing wavefront aberration data
And

In the present embodiment, the main control device 30 is configured by combining various devices as described above. However, the main control device 30 is configured as a computer system,
It is also possible to realize the function of each of the above-described devices constituting the unit 0 by a program built in the main control device 30.

Hereinafter, the exposure operation by the exposure apparatus 100 of this embodiment will be described with reference to the flowchart shown in FIG.
Description will be made with reference to other drawings as appropriate. The following operation is based on the premise that the wavefront sensor 90 is mounted on the wafer stage WS.
Assume that the wavefront data processing device 80 and the main control system 20 are connected to each other.

Further, the opening 91a of the sign plate 91 of the wavefront sensor 90 mounted on the wafer stage and the wafer stage W
It is assumed that the positional relationship with ST is accurately obtained by observing the two-dimensional position mark 91b with the alignment microscope AS. That is, based on the position information (speed information) output from the wafer interferometer 18, the opening 91
It is assumed that the XY position of “a” can be accurately detected, and the opening 91a can be accurately positioned at a desired XY position by controlling the movement of the wafer stage WST via the wafer stage driving unit 24. In the present embodiment, the positional relationship between the opening 91a and the wafer stage WST is determined by the four two-dimensional position marks 91 by the alignment microscope AS.
b, based on the detection result of the position b.
No. 9 and the like, so-called enhanced global alignment (hereinafter, referred to as “EGA”) or the like, is accurately detected using a statistical technique equivalent to that.

In the processing shown in FIG. 6, first, in subroutine 101, the wavefront aberration of projection optical system PL is measured. In the measurement of the wavefront aberration, as shown in FIG. 7, first, in step 111, a reticle loader (not shown) loads the measurement reticle RT for wavefront aberration measurement shown in FIG. 8 onto the reticle stage RST. . As shown in FIG. 8, the measurement reticle RT
A plurality (9 in FIG. 8) of pinhole patterns PH ₁
To PH _N (N = 9 in FIG. 8) are formed in a matrix along the X direction and the Y direction. Incidentally, the pinhole pattern PH ₁ ~PH _N is formed to a size in the region of the slit-shaped illumination area indicated by a dotted line in FIG. 8.

Subsequently, reticle alignment using a reference mark plate (not shown) arranged on wafer stage WST, measurement of a baseline amount using alignment microscope AS, and the like are performed. Then, the first pinhole pattern PH _{1 on} which the aberration measurement is performed is the projection optical system P
Reticle stage R so as to be located on optical axis AX of L
Move ST. This movement is performed by the main control system 20 based on the position information (speed information) of the reticle stage RST detected by the reticle interferometer 16.
This is performed by controlling the reticle driving unit via the.

[0082] Returning to FIG. 7, then, in step 112, the opening 91a of marking plate 91 of the wavefront sensor 90, when the conjugate position (pinhole pattern PH ₁ for the projection optical system PL of the pinhole pattern PH ₁ is , Optical axis AX
The wafer stage WST is moved to (top). The movement is performed by main control system 20 based on position information (speed information) of wafer stage WST detected by wafer interferometer 18.
Wafer stage driving unit 24 via stage control system 19
Is performed by controlling. At this time, the main control system 20
Based on the detection result of the multiple focal position detection system (21, 22), the image plane pinhole image of the pinhole pattern PH ₁ is imaged so as to match the upper surface of marking plate 91 of the wavefront sensor 90 The wafer stage WST is minutely driven in the Z-axis direction via the wafer stage drive unit 24.

[0083] As described above, the arrangement of the optical the devices for the wavefront aberration measurement of the projection optical system PL related to the spherical wave from the first pinhole pattern PH ₁ is completed. For such an optical arrangement, the optical axis A of the wavefront sensor 90
FIG. 9 shows an image developed along the optical axes of X1 and the projection optical system PL.

[0084] In this optical arrangement, the illumination light IL is emitted from the illumination system 10, the light that has reached the first pinhole pattern PH ₁ of the measurement reticle RT is emitted from the pinhole pattern PH becomes a spherical wave I do. After passing through the projection optical system PL, the light is condensed on the opening 91 a of the sign plate 91 of the wavefront sensor 90. It should be noted that at the beginning of the pinhole pattern PH ₁ except pinhole pattern PH ₂ to P of
The light passing through the H _N does not reach the opening pattern 91a. The wavefront of the light condensed on the opening 91a in this manner is substantially spherical, but includes the wavefront aberration of the projection optical system PL.

The light that has passed through the opening 91a is converted into a plane wave by the collimator lens 92,
After passing through 3, the light enters the microlens array 94.
Here, the wavefront of the light incident on the microlens array 94 reflects the wavefront aberration of the projection optical system PL. That is, when the projection optical system PL has no wavefront aberration, as shown by a dotted line in FIG.
F is a plane orthogonal to the optical axis AX1, but the projection optical system P
When there is a wavefront aberration in L, the wavefront WF ′ is inclined at an angle corresponding to the position, as shown by a two-dot chain line in FIG.

The micro lens array 94 forms an image at the aperture 91a on the conjugate plane of the sign board 91, that is, the imaging plane 95S of the CCD 95, for each micro lens 94a. When the wavefront of the light incident on the micro lens 94a is orthogonal to the optical axis AX1, the micro lens 94a
A spot image centered on the intersection of the optical axis and the imaging surface is formed on the imaging surface 95S. When the wavefront of the light incident on the microlens 94a is inclined, a spot centered on a point shifted from the intersection of the optical axis of the microlens 94a and the imaging surface by a distance corresponding to the amount of the inclination. It is formed on the imaging surface 95S.

An example of the light intensity distribution J (X) of the spot image thus formed on the imaging surface 95S is shown by a solid line in FIG. In FIG. 10, the light intensity distribution in the X-axis direction of the spot image formed at the X position X _k is formed at X positions X _k−1 and X _{k + 1} adjacent to the spot image in the ± X direction. It is shown with a part of the light intensity distribution of the spot image. In FIG. 10, a light intensity distribution J ₀ (X) when an image is taken on the image plane CP is shown by a broken line for comparison. FIG. 10 shows the light intensity distributions J (X) and J ₀ (X) normalized so that the peak intensity of the spot image becomes 1.

As shown in FIG. 10, in the middle part of the spot images adjacent to each other, the light intensity distribution J (X) and the light intensity distribution J ₀ (X) have the same value and the light intensity distribution J ₀ (X) is the same. The full width at half maximum JW of (X) is smaller than the full width at half maximum JW ₀ of the light intensity distribution J ₀ (X). That is, in the imaging result on the imaging plane 95S, the spot diameter is smaller than when the image plane CP is used as the imaging plane. As a result, crosstalk between spot images can be reduced as compared with a case where a spot image is captured on the image plane CP.

For example, when the aperture of the microlens 94a is a square having a side of 0.4 mm, the focal length f is 200 mm, and the wavelength λ is 248 nm, the Fresnel number N of the microlens 94a is 1.61, and the image formed by the microlens 94a is obtained. Surface CP
The full width at half maximum JW ₀ of the light intensity distribution J ₀ (X) of the upper spot image is 0.111 mm. On the other hand, the imaging surface 95S
Is set at a position 40 mm (= d) away from the image plane CP, the full width at half maximum JW of the light intensity distribution J (X) is 0.100 mm. In this case, the image plane CP
At a distance d = 40 mm from the lens to the side of the microlens array 94 is 0.75 times the above-described defocus amount D, and the relative intensity I (u _N ) at that position is 1.36.
It has become.

Returning to FIG. 7, next, at step 113, an image formed on the image pickup surface 95S is picked up by the CCD 95. The imaging data IMD obtained by this imaging is supplied to the wavefront data processing device 80. In the wavefront data processing device 80, the imaging data collection device 33 collects the imaging data IMD, and stores the collected imaging data in the imaging data storage area 41.

Next, in step 114, the center position of each spot image is calculated by calculating the center of gravity of the light intensity distribution of each spot image based on the imaging result.

[0092] Then, in step 115, the wavefront aberration calculating unit 37, and the position information storage area 42 reads the detection result of the spot image position, the projection for light through the first pinhole pattern PH ₁ in the measurement reticle RT The wavefront aberration of the optical system PL is calculated. The calculation of the wavefront aberration is performed by calculating the coefficient of the Zernike polynomial from the difference between each spot image position expected when there is no wavefront aberration and the detected spot image position. Thus, the calculated wavefront aberration is represented by the pinhole pattern P
Together with the position of H _1, it is stored in the wavefront aberration storage area 43.

Next, in step 116, it is determined whether the wavefront aberration of the projection optical system PL has been calculated for all the pinhole patterns. At this stage, since only was only measured wavefront aberration of the projection optical system PL for the first pinhole pattern PH _1, negative determination is made, the process proceeds to step 117.

In step 117, the opening 91a of the sign board 91 of the wavefront sensor 90 is connected to the next pinhole pattern PH.
A conjugate position relative to a _second projection optical system PL moves the wafer stage WST. This movement is performed by the main control system 20.
This is performed by controlling the wafer stage driving unit 24 via the stage control system 19 based on the position information (speed information) of the wafer stage WST detected by the wafer interferometer 18. Also in this case, the main control system 20, based on the detection result of the multiple focal position detection system (21, 22), the wavefront sensor 90 to image plane pinhole image of the pinhole pattern PH ₂ is imaged The wafer stage WST is minutely driven in the Z-axis direction via the wafer stage drive unit 24, if necessary, so that the upper surfaces of the marking plates 91 coincide with each other.

Then, the above-mentioned pinhole pattern PH ₁
The wavefront aberration of the projection optical system PL is measured in the same manner as in the case. Then, the measurement result of the wavefront aberration, together with the position of the pinhole pattern PH _2, is stored in the wavefront aberration storage area 43.

Thereafter, in the same manner as described above, the wavefront aberration of the projection optical system PL for all the pinhole patterns is sequentially measured, and the measurement result for each aperture pattern is stored in the wavefront aberration storage area 43 together with the position of the aperture pattern. You. Thus, the projection optical system P for all pinhole patterns
When the wavefront aberration of L is measured, an affirmative determination is made in step 117. Then, the control device 39 reads the measurement result of the wavefront aberration from the wavefront aberration storage area 43 and supplies the result to the main control system 20 as the wavefront measurement result data WFA. Thereafter, the processing shifts to step 102 in FIG.

In step 102, the main control system 20 determines whether or not the measurement of the wavefront aberration of the projection optical system PL is equal to or less than an allowable value based on the wavefront measurement result data WFA supplied from the control device 39. . If this determination is affirmative, the process proceeds to step 104. On the other hand, if the determination is negative, the process proceeds to step 103. At this stage, the following description will be given assuming that the determination is negative and the process has proceeded to step 103.

In step 103, the main control system 20 controls the projection optical system PL to reduce the currently occurring wavefront aberration based on the measurement result of the wavefront aberration of the projection optical system PL.
Is adjusted. The adjustment of the wavefront aberration can be performed by the control device 39 controlling the movement of the lens element via the imaging characteristic correction controller 65 or, in some cases, manually adjusting the lens element of the projection optical system PL within the XY plane. It is performed by moving or exchanging lens elements.

Subsequently, in subroutine 101,
The wavefront aberration of the adjusted projection optical system PL is measured in the same manner as described above. Thereafter, the adjustment of the wavefront aberration of the projection optical system PL (Step 103) and the measurement of the wavefront aberration (Step 101) are repeated until a positive determination is made in Step 102. If a positive determination is made in step 102, the process proceeds to step 10
Move to 4.

In step 104, the wavefront sensor 90 is detached from the wafer stage WST, and the connection between the wavefront data processing device 80 and the main control system 20 is cut off.
Under the control of 0, a reticle R on which a pattern to be transferred is formed is loaded on a reticle stage RST by a reticle loader (not shown). Further, a wafer W to be exposed is placed on a wafer stage WS by a wafer loader (not shown).
Loaded on T.

Next, in step 105, under the control of the main control system 20, measurement for exposure preparation is performed. That is, preparation operations such as reticle alignment using a reference mark plate (not shown) arranged on wafer stage WST, and measurement of a baseline amount using alignment microscope AS are performed. Further, when the exposure of the wafer W is the exposure of the second and subsequent layers, in order to form a circuit pattern with a high degree of overlay accuracy with the already formed circuit pattern, the wafer E is measured by the above-described EGA measurement using the alignment microscope AS. The array coordinates of the shot area on W are detected with high accuracy.

Next, in step 106, exposure is performed. In this exposure operation, first, wafer stage WST is moved so that the XY position of wafer W becomes the scanning start position for exposure of the first shot area (first shot) on wafer W. Position information (speed information) from the wafer interferometer 18 and the like (in the case of exposure of the second and subsequent layers, the detection result of the positional relationship between the reference coordinate system and the array coordinate system, the position information from the wafer interferometer 18 ( The speed control is performed by the main control system 20 via the stage control system 19 and the wafer stage drive unit 24. At the same time, reticle stage RST is moved such that the XY position of reticle R becomes the scanning start position. This movement is performed by the main control system 20 via the stage control system 19 and a reticle driving unit (not shown).

Next, the stage control system 19 controls the main control system 2
0, a multi-point focus position detection system (2
The Z position information of the wafer detected by (1, 22), the XY of the reticle R measured by the reticle interferometer 16
Based on the position information and the XY position information of the wafer W measured by the wafer interferometer 18, the reticle R and the reticle R are adjusted while adjusting the surface position of the wafer W via a reticle driving unit and a wafer stage driving unit 24 (not shown). Scanning exposure is performed by relatively moving the wafer W.

When the exposure of the first shot area is completed, the wafer stage WST is moved so that the scanning start position for the exposure of the next shot area is moved, and the XY position of the reticle R is changed to the scanning start position. Reticle stage RST is moved to a position. Then, the scanning exposure for the shot area is performed in the same manner as in the first shot area. Thereafter, scanning exposure is performed for each shot area in the same manner, and the exposure is completed.

Then, in step 107, the wafer W that has been exposed is unloaded from the wafer holder 25 by an unloader (not shown). Thus, the exposure processing for one wafer W is completed.

In the subsequent exposure of the wafer, the measurement and adjustment of the wavefront aberration relating to the projection optical system PL in steps 101 to 103 are performed as necessary.
4 to 107 wafer exposure operations are performed.

As described above, according to the present embodiment, the micro lenses 94a constituting the micro lens array 94
Since the image of the spot is taken as a surface where the full width at half maximum of the light intensity distribution of the spot image is smaller than the image surface of the spot image, the amount of crosstalk between the spot images in the imaging result can be reduced, and the position of the spot image can be accurately determined. Can be found well. Then, since the wavefront aberration of the projection optical system PL is calculated using the spot image position obtained with high accuracy, the wavefront aberration of the projection optical system PL can be obtained with high accuracy.

Further, since the position satisfying the condition of the above expression (3) is taken as the imaging plane, the full width at half maximum of the light intensity distribution is less than 95% of the full width at half maximum of the light intensity distribution of the spot image on the image plane CP. It is possible to capture a spot image having a light intensity distribution having a full width at half maximum of, reduce the amount of crosstalk between spot images, and accurately determine the position of the spot image.

Further, since the position satisfying the condition of the above equation (2) is set as the imaging plane, it is possible to capture a spot image in which the influence of defocusing caused by imaging in the defocused state is suppressed. The image position can be obtained with high accuracy.

The projection optical system PL determined with high accuracy
The aberration of the projection optical system PL is adjusted based on the wavefront aberration, and a predetermined pattern formed on the reticle R is projected onto the surface of the wafer W by the projection optical system PL in which various aberrations are sufficiently reduced. Can be accurately transferred onto the wafer W.

In the above embodiment, the number of aperture patterns in the measurement reticle RT is nine, but the number can be increased or decreased according to the desired measurement accuracy of the wavefront aberration. Also, the number and arrangement of the microlenses 94a in the microlens array 94 can be changed according to the desired measurement accuracy of the wavefront aberration.

In the above embodiment, the target image for position detection is a spot image. However, an image of a pattern having another shape may be used.

In the above embodiment, the wavefront aberration measuring device 70 is separated from the exposure device main body 60 during exposure, but the exposure may be performed while the wavefront aberration measuring device 70 is mounted on the exposure device main body 60. Of course.

In the above embodiment, the projection optical system P
The description has been given of the case where the wavefront aberration measurement and the wavefront aberration adjustment of L are performed at the time of periodic maintenance or the like after the exposure apparatus is assembled, and preparations are made for subsequent exposure of the wafer. However, the adjustment of the projection optical system PL in the manufacture of the exposure apparatus has been described. At times, adjustment of the wavefront aberration may be performed in the same manner as in the above embodiment.
In adjusting the projection optical system PL at the time of manufacturing the exposure apparatus, in addition to the position adjustment of some lens elements constituting the projection optical system PL performed in the above embodiment, the position adjustment of other lens elements is performed. It is possible to rework the lens element, replace the lens element, and the like.

Further, in the above embodiment, the case of the scanning type exposure apparatus has been described. However, the present invention is not limited to a step-and-repeat machine, a step-and-scan machine as long as the exposure apparatus has a projection optical system. It can be applied to any step and stitching machine.

In the above embodiment, the present invention is applied to the measurement of the aberration of the projection optical system in the exposure apparatus. However, the present invention is not limited to the exposure apparatus, but may be used to measure various aberrations of the imaging optical system in other types of apparatuses. The present invention can be applied.

Further, the present invention can be applied to measurement of optical characteristics of various optical systems, such as the shape of a reflecting mirror, other than the measurement of aberrations of the optical system.

<< Production of Device >> Next, production of a device using the exposure apparatus of the above embodiment will be described.

FIG. 11 shows the devices (semiconductor chips such as IC and LSI, liquid crystal panels, CCs) of this embodiment.
D, thin-film magnetic head, micromachine, etc.). As shown in FIG.
First, in step 201 (design step), a function design of a device (for example, a circuit design of a semiconductor device) is performed, and a pattern design for realizing the function is performed. Subsequently, in step 202 (mask manufacturing step), a mask on which the designed circuit pattern is formed is manufactured. On the other hand, in step 203 (wafer manufacturing step), a wafer is manufactured using a material such as silicon.

Next, in step 204 (wafer processing step), an actual circuit or the like is formed on the wafer by lithography using the mask and the wafer prepared in steps 201 to 203, as described later. Next, step 205 (device assembling step)
In step, chips are formed using the wafer processed in step 204. This step 205 includes processes such as an assembly process (dicing, bonding) and a packaging process (chip encapsulation).

Finally, step 206 (inspection step)
In step, inspections such as an operation confirmation test and a durability test of the device manufactured in step 205 are performed. After these steps, the device is completed and shipped.

FIG. 12 shows a detailed flow example of step 204 in the case of a semiconductor device. In FIG. 12, step 211 (oxidation step)
In, the surface of the wafer is oxidized. Step 212
In the (CVD step), an insulating film is formed on the wafer surface. In step 213 (electrode formation step), electrodes are formed on the wafer by vapor deposition. Step 2
At 14 (ion implantation step), ions are implanted into the wafer. Steps 211 to 214 described above
Each of them constitutes a pre-processing step in each stage of the wafer process, and is selected and executed according to a necessary process in each stage.

In each stage of the wafer process, when the pre-processing step is completed, the post-processing step is executed as follows. In this post-processing step, first, step 215
In (resist forming step), a photosensitive agent is applied to the wafer, and subsequently, in step 216 (exposure step), the circuit pattern of the mask is printed and exposed on the wafer by the exposure apparatus and the exposure method of the embodiment described above. Next, in step 217 (development step), the exposed wafer is developed, and subsequently, in step 218
In the (etching step), the exposed member other than the portion where the resist remains is removed by etching. Then, in step 219 (resist removing step), unnecessary resist after etching is removed.

By repeating these pre-processing and post-processing steps, multiple circuit patterns are formed on the wafer.

As described above, a device in which a fine pattern is accurately formed is manufactured.

[0126]

As described above in detail, according to the optical characteristic measuring method of the present invention, the plane where the full width at half maximum of the light intensity distribution of the spot image is smaller than the image plane of the light-collecting element is taken as the imaging plane. An image of a spot is taken, and the amount of crosstalk between spot images in the image pickup result is reduced. Then, based on the imaging result of the spot in which the crosstalk is reduced, the spot image position is obtained with high accuracy, and the wavefront aberration of the projection optical system PL is calculated using the accurately obtained spot image position. Therefore, the wavefront aberration of the projection optical system PL can be obtained with high accuracy.

According to the optical characteristic measuring apparatus of the present invention, the optical characteristic of the test optical system is measured using the optical characteristic measuring method of the present invention. And it can detect with high precision.

[Brief description of the drawings]

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

FIG. 2 is a diagram schematically illustrating a configuration of a wavefront sensor in FIG. 1;

FIG. 3 is a view for explaining a surface state of the marking plate of FIG. 2;

FIGS. 4A and 4B are diagrams showing a configuration of the microlens array of FIG. 2;

FIG. 5 is a block diagram illustrating a configuration of a wavefront data processing device in FIG. 1;

FIG. 6 is a flowchart for explaining processing in an exposure operation by the apparatus of FIG. 1;

FIG. 7 is a flowchart illustrating a process in an aberration measurement subroutine of FIG. 6;

FIG. 8 is a diagram showing an example of a measurement pattern formed on a measurement reticle.

FIG. 9 is a diagram for explaining an optical arrangement when measuring wavefront aberration.

FIG. 10 is a diagram illustrating an example of a light intensity distribution of a captured spot image.

11 is a flowchart for explaining a device manufacturing method using the exposure apparatus of FIG.

FIG. 12 is a flowchart of a process in a wafer processing step of FIG. 11;

[Explanation of symbols]

36: Position information calculation device, 37: Wavefront aberration calculation device (optical characteristic calculation device), 60: Exposure device main body, 70: Wavefront aberration measurement device (optical characteristic measurement device), 94: Microlens array (wavefront division optical system) , 94a: microlens (light-collecting element, lens element), 95: imaging device, 95S:
Imaging surface, 100: exposure apparatus, PL: projection optical system (optical system to be inspected), W: wafer (substrate).

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01B 11/24 K (72) Inventor Katsura Katsura 3-2-3 Marunouchi, Chiyoda-ku, Tokyo Nikon Corporation F term (reference) 2F065 AA02 AA54 AA65 BB02 BB28 CC17 FF51 GG04 HH04 JJ03 JJ26 MM02 PP12 QQ13 QQ21 QQ23 QQ32 2G086 HH06 5F046 BA03 CB12 CB13 CB25 DA12

Claims (17)

[Claims] 1. A method for measuring optical characteristics of an optical system to be measured, comprising: a spot forming step of forming a spot for each divided wavefront obtained by dividing a light passing through the optical system to be tested into wavefronts; An imaging plane in which the full width at half maximum of each light intensity distribution of the spot is less than the full width at half maximum of each light intensity distribution of the spot on the imaging plane of the spot determined when the light passing through the optical system to be tested is wavefront split. A spot imaging step of imaging the spot at a position; a position information calculating step of calculating position information of each of the spots based on an imaging result in the spot imaging step; and using the calculated position information, An optical characteristic calculating step of calculating an optical characteristic of the test optical system. 2. A Fresnel number of a light condensing element for dividing a light passing through the test optical system into a wavefront is equal to or less than 4.86. 2. The optical characteristic measuring method according to claim 1, wherein the position is 95% or less of a full width at half maximum of each light intensity distribution of the spot on the image plane of the light condensing element. 3. The light transmitted through the optical system under test is split into wavefronts.
Point farthest from the center of the opening
A, the focal length of the light-collecting element is f,
The wavelength of the light passing through the optical analysis system is λ, the Fresnel number is N,
Parameter u _NU_N= (2πa^Two/ (F · λ)) · ((− d / f) / (1- (d / f))), the imaging plane position is I (u_N) = (1+ (u_N/ 2πN))^Two・ (2 / (u_N/ 2)^Two) ・ (1-cos (u_N/ 2))
> 1.05 from the position of the image plane by the distance d.
3. The method according to claim 1, further comprising:
The method for measuring optical characteristics according to 1. 4. The imaging surface position is a position closer to the light-collecting element from a position on the image surface by a distance d that further satisfies d <f ² · λ / (2a ² + f · λ). The method for measuring optical characteristics according to claim 3, wherein: 5. In the opening of the light-collecting element, the distance from the center of the opening to the farthest point is a, the focal length of the light-collecting element is f, and the wavelength of light passing through the test optical system is 5. When λ is set, the imaging plane position is a position separated from the image plane by a distance less than a distance D defined by D = f ² · λ / (2a ² + f · λ). The method for measuring optical characteristics according to claim 1. 6. An optical characteristic measuring apparatus for measuring optical characteristics of a test optical system, comprising: a plurality of light-collecting elements, wherein the test optical system is arranged in accordance with an arrangement of the plurality of light-collecting elements. A wavefront splitting optical system that splits the transmitted light into wavefronts to form spots for each split wavefront; and that the full width at half maximum of each light intensity distribution of the spot is equal to the light intensity distribution of the spot on the image plane of the light condensing element. An imaging device in which an imaging surface is arranged at a position where the width is less than the full width at half maximum of the optical characteristic measuring device. 7. The device according to claim 6, wherein each of the light-collecting elements is a lens element, and the wavefront splitting optical system includes a microlens array in which the lens elements are two-dimensionally arranged. Optical property measuring device. 8. The light-collecting element has a Fresnel number of 4.86 or less, and the imaging surface has a full width at half maximum of each light intensity distribution of the spot, and a light intensity of the spot on an image plane of the light-collecting element. The optical property measuring apparatus according to claim 6, wherein the optical property measuring apparatus is arranged at a position where the distribution is 95% or less of a full width at half maximum. 9. A distance from the center of the opening to the farthest point in the opening of the light-collecting element, a focal length of the light-collecting element, and a wavelength of light passing through the test optical system. λ, the Fresnel number is N, and the parameter u _N is defined as u _N = (2πa ² / (f · λ)) · ((− d / f) / (1- (d / f))), the imaging _{surface, I (u N) = (} 1+ (u N / 2πN)) 2 · (2 / (u N / 2) 2) · (1-cos (u N / 2))
7. The image forming apparatus according to claim 6, wherein the distance d satisfies> 1.05 from the position of the image plane to a position closer to the light-collecting element.
The optical property measuring device according to any one of claims 8 to 8. 10. The imaging surface is disposed at a position closer to the light-collecting element from the position of the image surface by a distance d that further satisfies d <f ² · λ / (2a ² + f · λ). The optical characteristic measuring device according to claim 9, wherein: 11. Within the opening of the light-collecting element, a is the distance from the center of the opening to the farthest point, f is the focal length of the light-collecting element, and W is the wavelength of light passing through the test optical system. When λ, the imaging surface is arranged at a position separated from the image surface by a distance less than a distance D defined by D = f ² λ / (2a ² + f ・ λ). The optical characteristic measuring device according to claim 6. 12. A position information calculation device for calculating position information of the spot image based on an image pickup result by the image pickup device; and calculating an optical characteristic of the optical system to be measured by using the calculated position information. The optical characteristic measuring device according to any one of claims 6 to 11, further comprising: an optical characteristic calculating device. 13. irradiating the substrate with exposure light,
An exposure apparatus for transferring a predetermined pattern onto the substrate, comprising: an exposure apparatus main body having a projection optical system arranged on an optical path of the exposure light; and the projection optical system being a test optical system. An optical device for measuring an optical property according to any one of claims 12 to 12. 14. An optical system whose optical characteristics have been measured using the optical characteristic measuring device according to claim 6. Description: 15. An optical characteristic adjusting method for adjusting an optical characteristic of an optical system, wherein the optical characteristic of the optical system is measured by using the optical characteristic measuring device according to claim 6. Description: An optical property adjusting step of adjusting an optical property of the optical system based on a measurement result in the optical property measuring step. 16. By irradiating the substrate with exposure light,
A method of manufacturing an exposure apparatus for transferring a predetermined pattern onto the substrate, comprising: providing an exposure apparatus main body having a projection optical system arranged on an optical path of the exposure light; Preparing an optical characteristic measuring device according to any one of claims 6 to 12 as a system; and an optical characteristic measuring step of measuring an optical characteristic of the projection optical system using the optical characteristic measuring device. An optical characteristic adjusting step of adjusting an optical characteristic of the optical system based on a measurement result in an optical characteristic measuring step of the projection optical system. 17. A semiconductor device manufactured by using the exposure apparatus according to claim 13.