JP2002203763A - Optical characteristic measuring method and device, signal sensitivity setting method, exposure unit and device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure the best focus position of a projection optical system regardless of the type of the measuring mark. SOLUTION: A specified measuring mark is irradiated with illumination light, and a space image of the measuring mark is formed on the image surface through the projection optical system. A pattern for measurement is relatively scanned with respect to the space image and a photoelectric transfer signal corresponding to the intensity of the illumination light through the pattern for measurement is obtained in every position in the direction of the optical axis of the pattern for measurement. Then the region which is surrounded by the photoelectric transfer signals obtained in the positions in the direction of the optical axis of the pattern for measurement, for example, the waveform of signals P1 and P2 and the scanning axis of the pattern for measurement is divided into a first region A (area A) indicating that it is near the best focus position of the projection optical system, and a second region B (area B) indicating that it is far from the best focus position. The best focus position is detected by regarding the area ratio between the first region and the second region A/B as an evaluation amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for measuring optical characteristics, a method for setting signal sensitivity, an exposure apparatus, and a method for manufacturing a device. System optical characteristic measuring method, an optical characteristic measuring device for executing the optical characteristic measuring method, a signal sensitivity setting method of a signal processing system used for measuring an aerial image in the optical characteristic measuring method, and the optical characteristic measuring device The present invention relates to an exposure apparatus provided and a device manufacturing method using the exposure apparatus.

[0002]

2. Description of the Related Art Conventionally, when a semiconductor element or a liquid crystal display element is manufactured by a photolithography process, a pattern of a photomask or a reticle (hereinafter, collectively referred to as “reticle”) is formed on a surface through a projection optical system. Exposure apparatus for transferring onto a substrate such as a wafer or a glass plate on which a photosensitive agent such as a photoresist is coated, for example, a step-and-repeat type reduction projection exposure apparatus (so-called stepper), a step-and-scan method (A so-called scanning stepper) or the like is used.

When a semiconductor element or the like is manufactured, different circuit patterns need to be formed on the substrate in a number of layers, so that a reticle on which the circuit pattern is drawn and each shot area on the substrate are formed. It is important to accurately overlap the pattern already formed on the substrate. In order to perform such superposition with high accuracy, it is essential that the optical characteristics (including the imaging characteristics) of the projection optical system be adjusted to a desired state.

As a precondition for adjusting the optical characteristics of the projection optical system, it is necessary to accurately measure the optical characteristics. As one method of measuring the optical characteristics, a spatial image (projection image) of a measurement mark formed by a projection optical system by illuminating a measurement mask on which a measurement mark is formed with illumination light without actually performing exposure. A method of scanning a rectangular or slit opening pattern, photoelectrically converting light transmitted through the opening pattern to measure an aerial image, and calculating optical characteristics based on the measurement result (hereinafter, referred to as “ Aerial image measurement method).

In the aerial image measurement method, not only horizontal aberration such as distortion (including magnification) and coma of the projection optical system, but also vertical aberration such as best focus position, curvature of field and spherical aberration can be measured. It is possible.

[0006]

In the conventional aerial image measurement method, when measuring the best focus position of the projection optical system, the light intensity signal corresponding to the aerial image is Fourier-transformed, and for example, the amplitude of the primary frequency component is calculated. An evaluation amount based on the amplitude of a fundamental wave component such as contrast, which is a ratio to the amplitude of the 0th-order frequency component, has been used. For this reason, as the mark for measuring the best focus position, a repetitive mark having a relatively narrow pitch suitable for detecting the fundamental wave component, for example, a duty ratio which is a ratio of the width of the line portion to the width of the space portion is 1: 1.
Line and space marks, etc. were used.
The measurement of the best focus position using the line and space mark can be suitably used when manufacturing a memory such as a DRAM.

However, semiconductor exposure apparatuses are used not only for memories but also for manufacturing CPUs, system LSIs, and the like. For example, a CPU maker projects an image by aiming at an isolated line or a repetition mark having a relatively large repetition pitch. The emergence of a new technology capable of measuring the best focus position of an optical system is expected.

The best focus position of the projection optical system is determined by using a repetition mark having a relatively narrow pitch as a measurement mark, or using an isolated line or a repetition mark having a relatively large repetition pitch (pseudo isolated line). This is because the best focus position is different from the case where there is, but it is difficult to measure the latter case using the evaluation amount based on the amplitude of the fundamental wave component in the latter case.

The present invention has been made under such circumstances, and a first object of the present invention is to provide an optical characteristic capable of measuring the best focus position of a projection optical system with high accuracy regardless of the type of a measurement mark. It is to provide a measuring method and an apparatus.

A second object of the present invention is to provide a signal sensitivity setting method capable of measuring a light intensity distribution with high accuracy by making the most effective use of the resolution of a signal processing system. .

A third object of the present invention is to provide an exposure apparatus which realizes high-precision exposure by suppressing the occurrence of exposure failure due to defocus.

A fourth object of the present invention is to provide a device manufacturing method capable of improving device productivity.

[0013]

According to a first aspect of the present invention, there is provided an optical characteristic measuring method for measuring an optical characteristic of a projection optical system, wherein a predetermined measurement is performed using illumination light (IL). Illuminating a mark (PM) and forming an aerial image (PM ′) of the measurement mark on an image plane via the projection optical system; a measurement pattern arranged on the image plane side of the projection optical system (22) is scanned relative to the aerial image, and a photoelectric conversion signal corresponding to the intensity of the illumination light via the measurement pattern is provided for each of a plurality of positions in the optical axis direction of the measurement pattern. A region surrounded by the waveform of the photoelectric conversion signal obtained for each position in the optical axis direction of the measurement pattern and the scanning axis of the measurement pattern is set to a best focus position of the projection optical system. A first area indicating closeness and Detecting the best focus position using an area ratio between the first region and the second region as an evaluation amount, the second region indicating that the best focus position is far from the best focus position. This is a characteristic measurement method.

According to this, a predetermined measurement mark is illuminated by the illumination light, a spatial image of the measurement mark is formed on an image plane via a projection optical system, and a measurement pattern is relative to the spatial image. And a photoelectric conversion signal corresponding to the intensity of the illumination light via the measurement pattern is obtained for each of a plurality of positions in the optical axis direction of the measurement pattern. A region surrounded by the waveform of the photoelectric conversion signal obtained for each position in the optical axis direction of the measurement pattern and the scanning axis of the measurement pattern is a first region indicating that the region is close to the best focus position of the projection optical system. And a second area indicating that it is far from the best focus position, and the best focus position is detected using the area ratio between the first area and the second area as an evaluation amount. For this reason, the area surrounded by the waveform of each obtained photoelectric conversion signal and the scanning axis of the measurement pattern is reduced to two based on a predetermined reference without performing Fourier transformation or the like on the intensity signal (photoelectric conversion signal) of the aerial image. Just by separating, the best focus position of the projection optical system can be measured with high accuracy irrespective of the type of measurement mark due to the area ratio of these two regions.

In this case, there are various methods for setting the first area and the second area. For example, when the photoelectric conversion signal is an image intensity signal representing an intensity of an aerial image corresponding to each position of the measurement pattern as in the optical characteristic measurement method according to claim 2, the first region is A region having a predetermined width including a design best focus position when the region corresponding to the image intensity signal is divided along the position direction, and the second region is the remaining region that has been divided. It can be. Alternatively, when the photoelectric conversion signal is an image intensity signal representing an intensity of an aerial image corresponding to each position of the measurement pattern as in the optical characteristic measurement method according to claim 3, the first region is The region corresponding to the image intensity signal is a region closer to the maximum image intensity obtained by dividing the region corresponding to the predetermined image intensity threshold along the intensity direction, and the second region is the remaining divided region. Region.

In each of the optical characteristic measuring methods according to the first to third aspects, as in the optical characteristic measuring method according to the fourth aspect, the detection of the best focus position is performed at a different distance from the optical axis of the projection optical system. The step of detecting the image plane shape of the projection optical system can be further included by repeatedly performing the processing on a plurality of points.

In each of the optical characteristic measuring methods according to the first to fourth aspects, the measurement mark may be a line and space mark or the like having a short repetition period. As in the optical characteristic measuring method, the measurement mark may be an isolated linear pattern composed of at least one line pattern extending in a direction orthogonal to the scanning direction. here,
The “isolated linear pattern” is not only an isolated line pattern but also a so-called pseudo-isolated line and space mark in which the duty ratio, which is the ratio of the width of the line portion to the width of the space portion, is 1: (9 or more). Also includes line patterns. In this specification, the term “isolated linear pattern” is used in other parts in such a meaning.

In each of the optical characteristic measuring methods according to the first to fifth aspects, the measuring pattern may be a rectangular opening pattern or the like. For example, as in the optical characteristic measuring method according to the sixth aspect, The measurement pattern may be a slit-shaped opening pattern having a predetermined width extending in a direction orthogonal to the scanning direction in a two-dimensional plane perpendicular to the optical axis.

In each of the optical characteristic measuring methods according to the first to sixth aspects, as in the optical characteristic measuring method according to the seventh aspect, at the time of acquiring the photoelectric conversion signal, the photoelectric conversion signal corresponding to the intensity of the received signal light is obtained. A signal processing system including a photoelectric conversion element that outputs a conversion signal and a processing circuit to which the photoelectric conversion signal is input from the photoelectric conversion element is used, and an integral value of one peak of the photoelectric conversion signal is determined by the measurement mark. The signal sensitivity of the signal processing system is set so that the dynamic range of the signal processing system can be utilized as effectively as possible based on the value obtained by dividing the line width of the measurement pattern by the larger dimension of the width of the measurement pattern. You can do that.

The signal sensitivity setting method according to claim 8, wherein the photoelectric conversion element (24) for outputting a photoelectric conversion signal according to the intensity of the received signal light, and the photoelectric conversion signal from the photoelectric conversion element is input. A signal sensitivity setting method for setting a signal sensitivity of a signal processing system (50) including a signal processing circuit (42) to be performed, wherein the signal sensitivity is set via a linear pattern having a predetermined line width extending in a first direction on a first surface. Irradiating the illumination light onto the second surface by applying a measurement pattern having a predetermined width extending in the first direction on the second surface along the second direction orthogonal to the first direction. Scanning the light, receiving the illumination light via the measurement pattern by the photoelectric conversion element, and converting the illumination light into a photoelectric conversion signal corresponding to the intensity of the received light; and integrating the photoelectric conversion signal Based on the value, the dynamics of the signal processing system Setting the signal sensitivity of the signal processing system so as to make the best use of the cleanse;
The signal sensitivity setting method includes the following.

According to this, the illuminating light is radiated on the second surface via the linear pattern having a predetermined line width extending in the first direction on the first surface, and the predetermined light extending in the first direction on the second surface. The width measurement pattern is scanned with respect to the illumination light along a second direction orthogonal to the first direction, and the illumination light passing through the measurement pattern is received by the photoelectric conversion element and the received light is received. Is converted into a photoelectric conversion signal corresponding to the intensity of. Then, based on the integrated value of the photoelectric conversion signal, the signal sensitivity of the signal processing system is set so that the dynamic range of the signal processing system can be utilized most effectively. As described above, as a result of setting the signal sensitivity so that the dynamic range of the signal processing system can be effectively used as much as possible, it is possible to measure the intensity distribution of the illumination light with high resolution. Here, in the case where a projection optical system for projecting the illumination light emitted from the linear pattern onto the second surface is provided, the measurement pattern is scanned with respect to the illumination light along the second direction. Since the photoelectric conversion signal corresponding to the intensity of the aerial image of the linear pattern is output by the conversion element, the aerial image can be measured with high resolution and high accuracy.

In this case, as in the signal sensitivity setting method according to the ninth aspect, in the setting step, an integral value of one peak of the photoelectric conversion signal waveform is determined by measuring a line width of the linear pattern and the line width of the linear pattern. The signal sensitivity can be set based on a value obtained by dividing the larger one of the widths of the use patterns. Here, one peak of the photoelectric conversion signal waveform corresponds to, for example, a signal obtained from one linear pattern.

In each of the signal sensitivity setting methods according to the eighth and ninth aspects, as in the signal sensitivity setting method according to the tenth aspect, the photoelectric conversion element is a photomultiplier tube, and the photomultiplier tube is provided. The signal sensitivity can be set by setting the applied voltage to be applied.

An optical characteristic measuring device according to claim 11 is
An optical characteristic measuring device for measuring optical characteristics of a projection optical system (PL), wherein a spatial image (P) of a predetermined measurement mark (PM) is
An illumination device (10) for illuminating the measurement mark to form M ′) on the image plane via the projection optical system; and a measurement pattern (2) disposed on the image plane side of the projection optical system.
A pattern forming member (90) on which 2) is formed; a photoelectric conversion element (24) that outputs a photoelectric conversion signal according to the intensity of the illumination light via the measurement pattern; and the measurement mark by the illumination device. Is illuminated, and in a state where the aerial image is formed on the image plane, the pattern forming member is scanned so that the measurement pattern is relatively scanned with respect to the aerial image, and the photoelectric conversion element A measurement processing device (20) for measuring a light intensity distribution corresponding to the aerial image at each of a plurality of positions in the optical axis direction of the pattern forming member based on a photoelectric conversion signal from the apparatus; and a measurement result of the measurement processing device The area surrounded by the waveform of the photoelectric conversion signal obtained for each position in the optical axis direction of the pattern forming member and the scanning axis of the pattern forming member is the best focus of the projection optical system. A first area indicating that the position is closer to the best focus position and a second area indicating that the position is far from the best focus position. The area ratio between the first area and the second area is evaluated as the evaluation amount. And a calculating device (20) for calculating a focus position.

According to this, the measurement mark is illuminated by the illumination device, and a spatial image of the measurement mark is formed on the image plane via the projection optical system. In this state, the measurement processing device scans the pattern forming member so that the measurement pattern is relatively scanned with respect to the aerial image, and responds to the aerial image based on the photoelectric conversion signal from the photoelectric conversion element. The measured light intensity distribution is measured at each of a plurality of positions in the optical axis direction of the pattern forming member. Then, in the calculation device, a region surrounded by the waveform of the photoelectric conversion signal obtained for each position in the optical axis direction of the pattern forming member as a measurement result of the measurement processing device and the scanning axis of the pattern forming member is defined as a projection optical system. Are divided into a first region indicating that the position is close to the best focus position and a second region indicating that the position is far from the best focus position, and the area ratio between the first region and the second region is determined as the evaluation amount. Calculate the focus position. For this reason, the area surrounded by the waveform of each obtained photoelectric conversion signal and the scanning axis of the pattern forming member (measurement pattern) is determined without performing Fourier transform or the like on the intensity signal (photoelectric conversion signal) of the aerial image. Only by dividing into two, the best focus position of the projection optical system can be measured with high accuracy irrespective of the type of the measurement mark by the area ratio of the two regions.

In this case, as in the optical characteristic measuring device according to the twelfth aspect, the measurement mark is an isolated linear pattern composed of at least one line pattern extending in a direction orthogonal to the scanning direction. It can be.

[0027] In each of the optical characteristic measuring apparatuses according to the eleventh and twelfth aspects, as in the optical characteristic measuring apparatus according to the thirteenth aspect, the measurement pattern is scanned in a two-dimensional plane perpendicular to the optical axis. It may be a slit-shaped opening pattern of a predetermined width extending in a direction perpendicular to the direction.

In each of the optical characteristic measuring apparatuses according to the present invention, a signal processing system (50) having a predetermined dynamic range is provided together with the photoelectric conversion element as in the optical characteristic measuring apparatus according to the present invention. The signal processing circuit further includes a signal processing circuit (42) to which the photoelectric conversion signal is input, and the measurement processing device includes a signal sensitivity setting device (20) for setting a signal sensitivity of the signal processing system. The apparatus, when measuring the light intensity distribution corresponding to the aerial image based on the photoelectric conversion signal, based on the integral value of the photoelectric conversion signal, so that the dynamic range of the signal processing system can be utilized most effectively. The signal sensitivity of the signal processing system may be set.

In this case, as in the optical characteristic measuring device according to claim 15, the signal sensitivity setting device calculates an integral value of one peak of the photoelectric conversion signal with a line width of the measurement mark and the measurement pattern. The signal sensitivity may be set based on a value obtained by dividing by a larger one of the widths.

In the optical characteristic measuring device according to the present invention, when the photoelectric conversion element is a photomultiplier tube, the signal sensitivity setting device includes: The signal sensitivity can be set by setting the applied voltage applied to the photomultiplier tube.

In the exposure apparatus according to the present invention, the circuit pattern formed on the mask (R) is projected onto the projection optical system (PL).
An exposure apparatus for transferring the substrate to a substrate (W) via a substrate stage, wherein the substrate stage (WST) holding and moving the substrate; and the pattern forming member (90) are provided integrally with the substrate stage. An optical device for measuring an optical characteristic according to any one of Items 11 to 16;

According to this, since each of the optical characteristic measuring devices according to the present invention is provided with the pattern forming member integrally provided on the substrate stage, the optical characteristic measuring device allows the projection optical system to be formed. The best focus position can be measured with high accuracy. Since the optical positional relationship between the mask and the substrate can be adjusted to a desired positional relationship based on the measurement result of the best focus position, the occurrence of exposure defects due to defocus can be suppressed to achieve high-precision exposure. Can be realized.

The device manufacturing method according to claim 18 is
A device manufacturing method including a lithography step, wherein exposure is performed using the exposure apparatus according to claim 17 in the lithography step.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG. FIG. 1 shows a schematic configuration of an exposure apparatus 100 according to one embodiment. The exposure apparatus 100 is a step-and-scan type scanning projection exposure apparatus, that is, a so-called scanning stepper.

The exposure apparatus 100 holds an illumination system 10 as an illumination device including a light source and an illumination optical system, a reticle stage RST holding a reticle R as a mask, a projection optical system PL, and a wafer W as a substrate. A wafer stage WST as a substrate stage that can move freely in the XY plane and a control system for controlling these are provided.

The illumination system 10 includes a light source, an illuminance uniforming optical system (consisting of a collimator lens, a fly-eye lens, etc.), a relay lens system, a reticle blind as an illumination field stop, a condenser lens system, etc. (Not shown).

As the light source, here, for example, KrF excimer laser light (wavelength 248 nm) or A
An excimer laser light source that outputs rF excimer laser light (wavelength 193 nm) is used.

The reticle blind comprises a fixed reticle blind (not shown) having a fixed opening and a movable reticle blind 12 (not shown in FIG. 1; see FIG. 2) having a variable opening. The fixed reticle blind is disposed in the vicinity of the pattern surface of the reticle R or on a surface slightly defocused from the conjugate plane thereof, and a rectangular slit-shaped illumination area on the reticle R (in the X-axis direction which is a direction orthogonal to the plane of FIG. 1). It is elongated and has a rectangular opening that defines a rectangular slit-shaped illumination area (IAR) having a predetermined width in the Y-axis direction, which is a horizontal direction in the plane of the paper in FIG. The movable reticle blind 12 is disposed on a conjugate plane with respect to the pattern surface of the reticle R, and corresponds to a scanning direction (here, Y-axis direction) and a non-scanning direction (X-axis direction) at the time of scanning exposure. It has an opening whose position and width in the direction of movement are variable. However, in FIG. 2, for simplicity of explanation, the movable reticle blind 12 is shown as being arranged near the illumination system side with respect to the reticle R.

According to the illumination system 10, illumination light (hereinafter, referred to as "illumination light IL") as exposure light generated by the light source passes through a shutter (not shown) and then has an illuminance distribution almost uniform by an illuminance uniforming optical system. It is converted into a uniform light flux. The illumination light IL emitted from the illuminance uniforming optical system reaches the reticle blind via a relay lens system. The luminous flux passing through the reticle blind passes through a relay lens system and a condenser lens system to illuminate an illumination area IAR of the reticle R on which a circuit pattern and the like are drawn with uniform illuminance.

The movable reticle blind 12 is controlled by the main controller 20 at the start and end of the scanning exposure, and further restricts the illumination area IAR.
Exposure of unnecessary portions is prevented. In the present embodiment, the movable reticle blind 12 is
It is also used for setting an illumination area when measuring an aerial image by an aerial image measuring device described later.

A reticle R is fixed on the reticle stage RST by, for example, vacuum suction (or electrostatic suction). Here, reticle stage RST is driven by an unillustrated reticle stage drive system including a linear motor or the like, and XY perpendicular to optical axis AX of projection optical system PL described later.
It can be finely driven two-dimensionally in the plane (in the X-axis direction, the Y-axis direction, and the rotation direction (θz direction) around the Z-axis orthogonal to the XY plane), and Y is driven on a reticle base (not shown).
It can move at a specified scanning speed in the axial direction.
The reticle stage RST has a movement stroke in the Y-axis direction that allows the entire surface of the reticle R to cross at least the optical axis AX of the projection optical system PL.

On reticle stage RST, reticle laser interferometer (hereinafter referred to as “reticle interferometer”) 13
The movable mirror 15 that reflects the laser beam from the reticle stage RST is fixed, and the position of the reticle stage RST in the XY plane (including the rotation in the θz direction, which is the rotation direction about the Z axis) is, for example, 0 by the reticle interferometer 13. It is always detected with a resolution of about 0.5 to 1 nm. Here, actually, the scanning direction (Y-axis direction) at the time of scanning exposure is on the reticle stage RST.
And a moving mirror having a reflecting surface orthogonal to the non-scanning direction (X-axis direction). The reticle interferometer 13 has at least two axes in the Y-axis direction and at least two axes in the X-axis direction. Although one axis is provided, these are typically shown as a movable mirror 15 and a reticle interferometer 13 in FIG.

The position information of the reticle stage RST from the reticle interferometer 13 is sent to a main controller 20 comprising a workstation (or a microcomputer).
Main controller 20 drives and controls reticle stage RST via a reticle stage drive system based on position information of reticle stage RST.

The projection optical system PL is disposed below the reticle stage RST in FIG. 1 and its optical axis AX is set in the Z-axis direction. In this example, the projection optical system PL is a telecentric reduction system on both sides. A refractive optical system including a plurality of lens elements arranged at predetermined intervals along the optical axis is used. Here, the projection magnification of the projection optical system PL is, for example, 1/5. Therefore, when the slit-shaped illumination area IAR on the reticle R is illuminated by the illumination light IL from the illumination system 10, this reticle R
Of the reticle R in the slit-shaped illumination area IAR through the projection optical system PL, the reduced image (partially inverted image) of the illumination light IL passing through the wafer W on the surface of which the photoresist has been coated. It is formed in an exposure area IA conjugate to the illumination area IAR.

The wafer stage WST is freely driven along an upper surface of the stage base 16 in an XY two-dimensional plane (including a θz rotation) by a wafer stage drive system (not shown) composed of, for example, a magnetic levitation type two-dimensional linear actuator. It has become so. Here, since the two-dimensional linear actuator also has a Z drive coil in addition to the X drive coil and the Y drive coil, the wafer stage WST
The micro drive can be performed in three degrees of freedom, Z, θx (rotation direction around the X axis), and θy (rotation direction around the Y axis).

A wafer holder 25 is placed on wafer stage WST, and wafer W is held by wafer holder 25 by vacuum suction (or electrostatic suction).

Incidentally, instead of wafer stage WST, XY is driven by a drive system such as a linear motor or a planar motor.
When a two-dimensional moving stage driven only in a two-dimensional plane is used, the wafer holder 25 is set to three of Z, θx, and θy.
What is necessary is just to mount it on the two-dimensional movement stage via a Z leveling table that is minutely driven by, for example, a voice coil motor in the direction of freedom.

A movable mirror 27 for reflecting a laser beam from a wafer laser interferometer (hereinafter, referred to as a "wafer interferometer") 31 is fixed on the wafer stage WST. 5 degrees of freedom directions (X, Y, θz,
(θx and θz directions) are always detected at a resolution of, for example, about 0.5 to 1 nm.

Here, actually, wafer stage WST
A moving mirror having a reflecting surface orthogonal to the Y-axis direction, which is the scanning direction at the time of scanning exposure, and a moving mirror having a reflecting surface orthogonal to the X-axis direction, which is the non-scanning direction, are provided on the upper side. A plurality of shafts 31 are provided in the Y-axis direction and the X-axis direction, respectively.
Shown as wafer interferometer 31. The position information (or speed information) of wafer stage WST is sent to main controller 20. Main controller 20 controls the position of wafer stage WST via a wafer stage drive system (not shown) based on the position information (or speed information). The position in the XY plane is controlled.

Further, inside wafer stage WST,
A part of an optical system constituting an aerial image measuring instrument 59 used for measuring the optical characteristics of the projection optical system PL is arranged. Here, the configuration of the aerial image measuring device 59 will be described in detail. As shown in FIG. 2, the aerial image measuring device 59 includes a stage-side component provided on the wafer stage WST, that is, a slit plate 90 as a pattern forming member and a lens 8.
4, 86, a relay optical system, a mirror 88 for bending the optical path, a light transmitting lens 87, and a component outside the stage provided outside the wafer stage WST, ie, a mirror M,
A light receiving lens 89, an optical sensor 24 as a photoelectric conversion element,
And a signal processing circuit 42 for the photoelectric conversion signal from the optical sensor 24.

This will be described in more detail.
As shown in FIG. 2, is fitted from above into a protruding portion 58a provided on the upper surface of one end of wafer stage WST and having an open top, in a state of closing the opening.
The slit plate 90 has a rectangular light receiving glass 82 in a plan view.
A reflection film 83 also serving as a light-shielding film is formed on the upper surface of the substrate, and a part of the reflection film 83 has a predetermined width (2
D) slit-shaped opening pattern (hereinafter, “slit”)
22) is formed by patterning.

Here, as a material of the light receiving glass 82, synthetic quartz, fluorite, or the like, which has good transmittance of KrF excimer laser light or ArF excimer laser light, is used.

Wafer stage WST below slit 22
Inside, a mirror 8 for horizontally bending the optical path of the illumination light beam (image light beam) that has entered vertically downward through the slit 22.
8, a relay optical system (84, 86) composed of lenses 84, 86 is arranged, and the relay optical system (84, 86) is arranged.
A light transmitting lens 87 for transmitting the illumination light beam relayed by a predetermined optical path length by the relay optical system (84, 86) to the outside of the wafer stage WST is provided on the side wall on the + Y side of the wafer stage WST behind the optical path 86). Fixed.

The wafer stage W is transmitted by the light transmitting lens 87.
A mirror M having a predetermined length in the X-axis direction is inclined at an inclination angle of 45 ° on the optical path of the illumination light beam sent out of the ST. The mirror M allows the wafer stage W
The optical path of the illumination light beam sent to the outside of the ST is bent 90 ° vertically upward. A light receiving lens 89 having a larger diameter than the light transmitting lens 87 is arranged on the bent optical path. Above the light receiving lens 89, the optical sensor 24 is arranged. The light receiving lens 89 and the optical sensor 24 are housed in a case 92 while maintaining a predetermined positional relationship. The case 92 is located near an upper end of a support 94 implanted on the upper surface of the base 16 via a mounting member 93. Fixed.

As the optical sensor 24, a photoelectric conversion element (light receiving element) capable of accurately detecting weak light, for example, a photomultiplier tube (PM)
T, photomultiplier tube, etc. are used. The signal processing circuit 42 for the output signal of the optical sensor 24 is configured to include an amplifier, a sample holder, an A / D converter (usually, one having a resolution of 16 bits is used) (see FIG. 8).
In the present embodiment, the signal sensitivity (detection sensitivity) is set by setting the applied voltage between the cathode and the anode of the optical sensor 24. This will be described later.

As described above, the slits 22 are formed in the reflection film 83, but hereinafter, the description will be made on the assumption that the slits 22 are formed in the slit plate 90 for convenience.

According to the aerial image measuring device 59 configured as described above, when measuring a projection image (aerial image) of the measurement mark formed on the reticle R via the projection optical system PL, which will be described later. Light IL transmitted through the projection optical system PL
When the slit plate 90 constituting the aerial image measuring device 59 is illuminated by the illumination light IL transmitted through the slit 22 on the slit plate 90, the illumination light IL is transmitted through the lens 84, the mirror 88, the lens 86, and the light transmitting lens 87 to the wafer. Stage WST
It is led outside. Then, the wafer stage W
The light guided to the outside of the ST has its optical path bent vertically upward by the mirror M, is received by the optical sensor 24 via the light receiving lens 89, and is subjected to a photoelectric conversion signal (light amount) corresponding to the amount of light received from the optical sensor 24. The signal P is output to the main controller 20 via the signal processing circuit 42.

In the case of the present embodiment, the measurement of the projection image (spatial image) of the measurement mark is performed by the slit scan method.
9 and the optical sensor 24. Therefore, in the aerial image measuring device 59, the size of each lens and the mirror M is set such that all light passing through the light transmitting lens 87 moving within a predetermined range enters the light receiving lens 89.

As described above, in the aerial image measuring device 59, the light deriving unit that guides the light passing through the slit 22 to the outside of the wafer stage WST by the slit plate 90, the lenses 84 and 86, the mirror 88, and the light transmitting lens 87. Is formed, and the light receiving lens 89 and the optical sensor 24 are used to set the wafer stage W
A light receiving unit that receives the light led out of the ST is configured. In this case, the light guiding section and the light receiving section are mechanically separated. Then, only at the time of aerial image measurement, the light deriving unit and the light receiving unit are optically connected via the mirror M.

That is, in the aerial image measuring device 59, since the optical sensor 24 is provided at a predetermined position outside the wafer stage WST, the heat generation of the optical sensor 24 adversely affects the measurement accuracy and the like of the laser interferometer 31. Or give. Further, since the outside and inside of wafer stage WST are not connected by a light guide or the like, the driving accuracy of wafer stage WST is adversely affected as in the case where the outside and inside of wafer stage WST are connected by a light guide. Not even.

Of course, if the influence of heat can be eliminated, optical sensor 24 may be provided inside wafer stage WST. The shape, dimensions, and the like of the slit 22 on the slit plate 90 constituting the aerial image measuring device 59, and the aerial image measuring method and the optical characteristic measuring method performed using the aerial image measuring device 59 will be described in detail later. I do.

Returning to FIG. 1, on the side of the projection optical system PL,
Alignment mark (alignment mark) on wafer W
An off-axis alignment system ALG is provided as a mark detection system for detecting a mark. In the present embodiment, the alignment system ALG is an image processing type alignment sensor, so-called FIA (Field Image Alignment).
nt) system is used. This alignment system ALG
Are, as shown in FIG. 2, an alignment light source 32,
It is configured to include a half mirror 34, a first objective lens 36, a second objective lens 38, an image pickup device (CCD) 40, and the like. Here, a halogen lamp or the like that emits broadband illumination light is used as the light source 32. In this alignment system ALG, as shown in FIG. 3, the alignment mark M on the wafer W is irradiated by the illumination light from the light source 32 through the half mirror 34 and the first objective lens 36.
w, and the reflected light from the alignment mark portion is received by the image sensor 40 via the first objective lens 36, the half mirror 34, and the second objective lens 38. As a result, a bright field image of the alignment mark Mw is formed on the light receiving surface of the image sensor. Then, a photoelectric conversion signal corresponding to the bright-field image, that is, a light intensity signal corresponding to the reflection image of the alignment mark Mw is transmitted from the image sensor 40 to the main controller 2.
0 is supplied. Main controller 20 calculates the position of alignment mark Mw based on the detection center of alignment microscope ALG based on the light intensity signal, and calculates the calculation result and the wafer stage which is the output of wafer interferometer 31 at that time. Based on the location information of WST,
The coordinate position of the alignment mark Mw in the stage coordinate system defined by the optical axis of the wafer interferometer 31 is calculated.

Further, in the exposure apparatus 100 of this embodiment,
As shown in FIG. 1, an imaging light flux having a light source whose on / off is controlled by main controller 20 and for forming images of a large number of pinholes or slits toward an imaging surface of projection optical system PL. System 60a for irradiating the light from the oblique direction with respect to the optical axis AX, and a light receiving system 60b for receiving the reflected light flux of the imaging light flux on the surface of the wafer W. A system (focus sensor) is provided. When the focus fluctuation occurs in the projection optical system PL, the main controller 20 controls the inclination of the reflected light flux of the parallel plate (not shown) in the light receiving system 60b with respect to the optical axis, thereby controlling the focus fluctuation of the projection optical system PL. The calibration is performed by giving an offset to the multi-point focal position detection system (60a, 60b) in accordance with. Note that the focus position detection system (60a, 60
Multipoint focal position detection system (focus sensor) similar to b)
The detailed configuration of is disclosed in, for example, JP-A-6-283403.

The main controller 20 (not shown) so that the defocus becomes zero based on a defocus signal (defocus signal), for example, an S-curve signal from the light receiving system 60b at the time of scanning exposure to be described later. The movement of the wafer stage WST in the Z-axis direction and the inclination to two-dimensional points (that is, the rotation in the θx and θy directions) are controlled via the wafer stage drive system, that is, the multi-point focal position detection system (60a, 60b) Is used to control the movement of the wafer stage WST so that the image plane of the projection optical system PL and the surface of the wafer W substantially match within the irradiation area of the illumination light IL (the imaging relation with the illumination area IAR). Execute auto focus (auto focus) and auto leveling.

Next, the operation of the exposure step in the exposure apparatus 100 of this embodiment will be briefly described.

First, the reticle R is transported by a reticle transport system (not shown), and is held by suction on the reticle stage RST at the loading position. Next, the positions of wafer stage WST and reticle stage RST are controlled by main controller 20, and a projection image (spatial image) of a reticle alignment mark (not shown) formed on reticle R is read using aerial image measuring device 59. The measurement is performed as described later (see FIG. 2), and the projection position of the reticle pattern image is obtained. That is, reticle alignment is performed.

Next, main controller 20 moves wafer stage WST so that aerial image measuring device 59 is located immediately below alignment system ALG, and alignment system ALG serves as a position reference for aerial image measuring device 59. The slit 22 is detected. Main controller 20 aligns the projection position of the pattern image of reticle R with the projection position of the reticle pattern image based on the detection signal of alignment system ALG, the measurement value of wafer interferometer 31 at that time, and the projection position of the reticle pattern image obtained earlier. A relative position with respect to the system ALG, that is, a baseline amount of the alignment system ALG is obtained.

When the baseline measurement is completed, the main controller 20 performs wafer alignment such as EGA (Enhanced Global Alignment) disclosed in detail in, for example, JP-A-61-44429. The positions of all shot areas on W are determined. At the time of this wafer alignment, the wafer alignment mark Mw of a predetermined sample shot of a plurality of shot areas on the wafer W is measured as described above using the alignment system ALG (FIG. 2). reference).

Next, main controller 20 monitors wafer stage WST while monitoring position information from interferometers 31 and 13 based on the position information of each shot area on wafer W and the base line amount obtained above. Are positioned at the scanning start position of the first shot area, the reticle stage RST is positioned at the scanning start position, and scanning exposure of the first shot area is performed.

In other words, main controller 20 starts relative scanning of reticle stage RST and wafer stage WST in the Y-axis direction opposite to each other. When both stages RST and WST reach their respective target scanning speeds, exposure light EL Then, the pattern area of the reticle R starts to be illuminated, and the scanning exposure is started. Prior to the start of the scanning exposure, the light emission of the light source has been started, but the movement of each blade of the movable blind constituting the reticle blind is controlled by the main controller 20 in synchronization with the movement of the reticle stage RST. The shielding of the irradiation of the exposure light EL to the outside of the pattern area on the reticle R can be achieved by ordinary scanning / scanning.
Same as stepper.

In main controller 20, moving speed Vr of reticle stage RST in the Y-axis direction particularly during the scanning exposure described above.
Reticle stage RST and wafer stage WS such that the speed ratio of wafer stage WST in the X-axis direction is maintained at a speed ratio corresponding to the projection magnification of projection optical system PL.
T is controlled synchronously.

Then, different areas of the pattern area of the reticle R are sequentially illuminated with the ultraviolet pulse light, and the illumination of the entire pattern area is completed, thereby completing the scanning exposure of the first shot area on the wafer W. Thereby, the circuit pattern of the reticle R is changed to the first pattern via the projection optical system PL.
It is reduced and transferred to the shot area.

When the scanning exposure of the first shot area is completed, a stepping operation between shots for moving wafer stage WST to the scanning start position of the second shot area is performed. Then, the scanning exposure of the second shot area is performed in the same manner as described above. Thereafter, the same operation is performed in the third shot area and thereafter.

As described above, the stepping operation between shots and the scanning exposure operation for shots are repeated, and the pattern of the reticle R is transferred to all the shot areas on the wafer W by the step-and-scan method.

During the scanning exposure, the focus sensor (60) integrally attached to the projection optical system PL is used.
a, 60b), the above-described autofocus / autoleveling is performed.

By the way, in order for the pattern of the reticle R and the pattern already formed in the shot area on the wafer W to be accurately overlapped during the above-mentioned scanning exposure, the optical characteristics of the projection optical system PL and the baseline are required. It is important that the amount is accurately measured and that the optical characteristics of the projection optical system PL are adjusted to a desired state.

In this embodiment, an aerial image measuring device 59 is used for measuring the above-mentioned image forming characteristics. Hereinafter, the aerial image measurement by the aerial image measuring device 59 and the measurement of the optical characteristics of the projection optical system PL will be described in detail.

FIG. 2 shows a state in which the aerial image of the measurement mark formed on the reticle R is being measured using the aerial image measuring device 59. As the reticle R,
A dedicated aerial image measurement device or a device reticle having a dedicated measurement mark formed on a device reticle used for manufacturing a device is used. Instead of these reticles,
A reticle stage RST may be provided with a fixed mark plate (also called a reticle fiducial mark plate) made of a glass material of the same material as the reticle, and a mark plate having measurement marks formed thereon may be used.

Here, as shown in FIG. 2, it is assumed that a measurement mark PM composed of a line and space mark having periodicity in the Y-axis direction is formed at a predetermined position on the reticle R. In addition, as shown in FIG. 4A, the slit plate 90 of the aerial image measuring device 59 is formed with a slit 22 having a predetermined width 2D extending in the X-axis direction. Here, the predetermined width 2D is assumed to be about the half pitch of a line and space pattern with a duty ratio of 1: 1 at the resolution limit, for example, 2D = 0.2 μm. In the following, the line and space are abbreviated as “L / S” as appropriate.

In measuring the aerial image, the movable reticle blind 12 is driven by the main controller 20 via a blind driving device (not shown), and the illumination light IL of the reticle R is emitted.
Are defined only in the measurement mark PM portion (see FIG. 2). In this state, when illumination light IL is irradiated onto reticle R, as shown in FIG. 2, light (illumination light IL) diffracted and scattered by measurement mark PM is projected onto projection optical system PL.
And a spatial image (projection image) PM ′ of the measurement mark PM is formed on the image plane of the projection optical system PL. At this time, it is assumed that wafer stage WST is set at a position where the aerial image PM 'is formed on the + Y side (or -Y side) of slit 22 on slit plate 90 of aerial image measuring device 59. FIG. 4 is a plan view of the aerial image measuring instrument 59 at this time.
(A) is shown.

Main controller 20 moves wafer stage WST through a wafer stage drive system as shown in FIG.
When driven in the + Y direction as shown by an arrow F in (A), the slit 22 scans the aerial image PM ′ along the Y-axis direction. During this scanning, the light (illumination light IL) passing through the slit 22 is received by the optical sensor 24 via the light guide portion in the wafer stage WST and the light receiving lens 89, and the photoelectric conversion signal is transmitted to the signal processing circuit 42. The power is supplied to the main controller 20 via the main controller 20. Main controller 20 measures the light intensity distribution corresponding to aerial image PM ′ based on the photoelectric conversion signal.

FIG. 4B shows an example of a photoelectric conversion signal (light intensity signal) P obtained at the time of the aerial image measurement.

In this case, the spatial image PM 'is averaged due to the width (2D) of the slit 22 in the scanning direction (Y-axis direction).

Therefore, assuming that the slit is p (y), the intensity distribution of the aerial image is i (y), and the observed light intensity signal is m (y), the intensity distribution of the aerial image is i (y). The relationship between the intensity signals m (y) can be expressed by the following equation (1).
In the equation (1), the intensity distribution i (y) and the intensity signal m
The unit of (y) is the intensity per unit length.

[0085]

(Equation 1)

[0086]

(Equation 2)

That is, the observed intensity signal m (y) is a convolution of the slit p (y) and the intensity distribution i (y) of the aerial image.

Therefore, from the viewpoint of measurement accuracy, the smaller the slit width 2D is, the better. When the PMT is used as the optical sensor 24 as in the present embodiment, the scanning speed is reduced even when the slit width is very small. It is possible to detect the light amount (light intensity) if the measurement is delayed and time is taken for the measurement. However, in reality, the scanning speed at the time of measuring the aerial image has a certain restriction from the viewpoint of throughput. Therefore, if the slit width 2D is too small, the amount of light transmitted through the slit 22 becomes too small, and the measurement becomes impossible. It will be difficult.

According to the knowledge obtained by the inventor through simulations and experiments, the optimum value of the slit width 2D is about half the resolution limit pitch of the exposure apparatus (the pitch of the L / S pattern having a duty ratio of 1: 1). Therefore, in the present embodiment, it is set as such.

The aerial image measuring device 59 and the aerial image measuring method using the same are described in the following. Detection of the best focus position, b. Detection of the image forming position of the pattern image in the XY plane,
c. Used for baseline measurement of the alignment system ALG.

In the exposure apparatus 100 of the present embodiment, c.
Baseline measurement has already been described. B.
In the detection of the image forming position of the pattern image in the XY plane, there is no need to change the measurement method between a repetitive pattern with a relatively narrow pitch and a repetitive pattern with an isolated line or a relatively wide pitch. Since the relationship with the invention is weak, the following a. The detection of the best focus position will be described.

The detection of the best focus position is used, for example, for the purpose of detecting the best focus position of the projection optical system PL and detecting the best imaging plane (image plane).

In the present embodiment, as an example, the best focus position of the projection optical system PL is detected as follows.

For detecting the best focus position, for example, a line width of 0.15 μm on a wafer (0.75 μm on a reticle) and a pitch of 1.5 μm (duty ratio 1:
The reticle R in which the L / S mark of 9) is formed as the measurement mark PM is used.

First, reticle R is loaded on reticle stage RST by a reticle loader (not shown).
Next, main controller 20 sets measurement mark P on reticle R at a predetermined point (here, on the optical axis of projection optical system PL) at which the best focus position is to be measured in the field of view of projection optical system PL.
The reticle stage RST is moved so that M is positioned.

Next, the main controller 20 controls the driving of the movable reticle blind 12 so as to irradiate only the measurement mark PM with the illumination light IL to define an illumination area.
In this state, main controller 20 irradiates reticle R with illumination light IL, and performs wafer stage W
While scanning ST in the Y-axis direction, the aerial image measurement of the measurement mark PM is performed by the slit scan method using the aerial image measuring device 59 in the same manner as described above. At this time, main controller 20 repeats a plurality of times while changing the position of slit plate 90 in the Z-axis direction (that is, the Z position of wafer stage WST) at, for example, about 15 steps at a pitch of 0.1 μm.
The light intensity signal (photoelectric conversion signal) of each time is stored in the internal memory. The step range is performed, for example, in a range around the design best focus position.

Here, at the time of the aerial image measurement described above, the slit plate 90 is scanned at the first Z position, and the measurement mark P
When the light intensity signal corresponding to the aerial image of M is captured,
The detection sensitivity is set (calibrated) so as to make the best use of the dynamic range of the signal processing circuit 42 at the subsequent stage of the optical sensor 24. This will be described later.

In this case, for example, when the measurement mark is an L / S mark (L / S pattern) having a duty ratio of 1: 1, the above light intensity signals are Fourier-transformed, and the respective primary frequency components and 0 The contrast which is the amplitude ratio of the next frequency component is obtained. Since this contrast changes sensitively depending on the focus position, it is convenient to determine the best focus position from the intensity signal. However, in the case of a measurement mark PM composed of an L / S pattern (pseudo isolated line) having a duty ratio of 1: 9, focus detection using a primary frequency component is inaccurate due to a large pattern repetition pitch. This is because the DOF of the dull pattern is large. However, since the amplitude of a high-order frequency component is not sufficiently large, even if focus detection is performed using only the amplitude of a high-order single frequency component, accuracy is still poor.

Therefore, in the present embodiment, main controller 20
Calculates the best focus position by the following first and second methods based on a plurality of light intensity signals (photoelectric conversion signals) obtained by the repetition.

A. First Method This first method uses an area corresponding to a light intensity signal corresponding to an aerial image of an isolated line (or a single line pattern of a pseudo isolated line) in an XY plane of a design pattern. The center area of the design line width centered on the imaging position (center position) (first area)
Area) and peripheral areas (second areas) on both sides thereof, and the best focus position is obtained using the area ratio of the two as an evaluation amount. Hereinafter, the detection principle of the first method will be described with reference to FIGS.

FIG. 5A shows the slit transmitted light intensity in the best focus state obtained as a result of a simulation in which a measurement mark having the same size as the above-mentioned measurement mark PM and a slit width are set. Position (or Y position of wafer stage WST),
In FIG. 5B, the horizontal axis of the slit transmitted light intensity in the state of 1 μm defocus is shown as the Y position of the slit 22 (or the Y position of the wafer stage WST).

In FIG. 5A, the image forming position (center position) in the designed XY plane of one line pattern of the measurement mark PM surrounded by the light intensity signal P ₁ and the horizontal axis is set as the center. Assuming that the area ratio of the area A = A ₁ of the area of the design line width to the area B = B ₁ (= b ₁ + b ₂ ) of the area on both sides thereof is α ₁ ,
α ₁ is represented by the following equation (3). α ₁ = A ₁ / B ₁ (3)

On the other hand, in FIG. 5B, the light intensity signal P
Area A = A ₂ of the area of the design line width centered on the designed image forming position (center position) in the XY plane of one line pattern of the measurement mark PM surrounded by ₂ and the horizontal axis; Assuming that the area ratio of the area B = B ₂ (= b ₃ + b ₄ ) of the regions on both sides is α ₂ , α ₂ is represented by the following equation (4). α ₂ = A ₂ / B ₂ (4)

As is clear from the comparison between FIG. 5A and FIG. 5B, α ₁ > α ₂ .

Therefore, the area ratio α expressed by the following equation (5)
Is used as the evaluation amount, the best focus position can be detected with high accuracy. Area ratio α = A / B (5)

There are various methods for obtaining the best focus position using the above-mentioned area ratio α as an evaluation amount. As an example, as shown in FIG. 6, for each position (Z position) of the slit plate 90 in the optical axis direction, as shown in FIG. The area ratio α calculated based on the obtained light intensity signal is plotted on an orthogonal coordinate system having the horizontal axis as the Z position (see the crosses in FIG. 6). Then, each plot point is approximated by a curve (curve fit). For example, a fourth-order approximate curve is obtained by the least square method. Then, the approximate curve is sliced at an appropriate threshold level (slice level) SL, and the slice level SL
The intersections J and K of the curve and the approximate curve are obtained, and the intersections J and K
The intersection G between the axis parallel to the vertical axis (the axis of the evaluation amount α) passing through the middle point (the point at a distance L / 2 from each of the points J and K) O is defined as the peak point of the approximate curve, and the peak point G _{Is set} as the best focus position.

As described above, when measuring the best focus position, the aerial image measurement is usually performed by the slit scan method while changing the Z position by about 15 steps at a pitch of about 0.1 μm. In this case, in order to improve the measurement reproducibility, it is important to determine the peak position from information on as many measurement points (Z positions) as possible. FIG. 6 shows an example in which the best focus position is obtained from the area ratio α at 13 points.

B. Second Method In the second method, a region corresponding to a light intensity signal corresponding to an aerial image of an isolated line (or a single line pattern of a pseudo isolated line) is divided into two by a predetermined threshold level as a boundary. , A region above the threshold level (first region) and a region below the threshold level (second region).
This is a method of obtaining the best focus position using the area ratio of the (area) as an evaluation amount. Hereinafter, the detection principle of the second method will be described with reference to FIGS. 7A and 7B.

FIGS. 7A and 7B show FIG.
5 (A) and FIG. 5 (B), the horizontal axis of the slit transmitted light intensity obtained as a result of the completely same simulation is the Y position of the slit 22 (or the Y position of the wafer stage WST).
It is shown as

[0110] In FIG. 7 (A), in the region surrounded by the light intensity signal P ₁ and the horizontal axis, the area C = C of the upper regions bisected with respect to a boundary of a predetermined slice level (threshold level) SL ' ₁ and the area ratio of the area of the lower region E = E ₁ to γ
When _1, gamma ₁ is expressed by the following equation (6). γ ₁ = C ₁ / E ₁ (6)

Here, the slice level SL 'is obtained by, for example, previously obtaining the light intensity at the peak point in the best focus state by an experiment or the like, and is set to, for example, a level of about 50% thereof.

On the other hand, in FIG. 7B, the light intensity signal P
_Since the area C = 0 of the area above the predetermined slice level (threshold level) SL ′ in the area surrounded by ₄ and the horizontal axis, the area E below it and the slice level (threshold level) SL ′ = When the area ratio of E ₂ and gamma _2, gamma ₂ is
It is expressed by the following equation (7). γ ₂ = 0 / E ₂ = 0 (7) In this case, obviously, γ ₁ > γ ₂ .

Therefore, the area ratio γ represented by the following equation (8)
Is used as the evaluation amount, the best focus position can be detected with high accuracy. Area ratio γ = C / E (8)

Also in this case, when determining the best focus position using the area ratio γ as an evaluation amount, the best focus position is calculated based on the light intensity signal obtained for each position (Z position) of the slit plate 90 in the optical axis direction. The plotted area ratio γ is plotted on an orthogonal coordinate system having the horizontal axis as the Z position, each plot point is approximated by a curve, and the peak point of the approximate curve is obtained based on the slice midpoint method described above. The method of setting the coordinate of the horizontal axis corresponding to the point as the best focus position can be adopted as it is.

The detection of the image plane shape of the projection optical system PL can be performed as follows.

First, reticle R is loaded on reticle stage RST by a reticle loader (not shown).
Next, main controller 20 controls reticle stage RST such that measurement mark PM is positioned at the first detection point (here, on the optical axis of projection optical system PL) in the field of view of projection optical system PL. Moving. Next, main controller 20 drives and controls movable reticle blind 12 so that illumination light IL is emitted only to measurement mark PM, and defines an illumination area. In this state, the main controller 20 controls the illumination light I
L is irradiated onto the reticle R, and in the same manner as described above, the aerial image measurement of the measurement mark PM and the detection of the best focus position Z ₁ of the projection optical system PL are performed using the aerial image measurement device 59 by the slit scan method. The result is stored in the internal memory.

When the detection of the best focus position at the first detection point in the field of view of projection optical system PL is completed, main controller 20 sets measurement mark PM at the second detection point in the field of view of projection optical system PL. The reticle stage RST is moved so that is positioned. Next, main controller 20 drives and controls movable reticle blind 12 so that illumination light IL is emitted only to measurement mark PM, and defines an illumination area. In this state, similarly to the above, the aerial image measurement and projection optical system P of the measurement mark PM is performed by the slit scan method.
Performs detection of the best focus position Z ₂ of the L, and the result is stored in the internal memory.

Thereafter, main controller 20 changes the detection point in the field of view of projection optical system PL and measures the aerial image of measurement mark PM and changes projection optical system PL in the same manner as described above.
Is repeatedly detected.

[0119] This the best focus position obtained by Z _1, Z _2, ......, based on Z _n, by performing a predetermined statistical processing, to calculate the image plane shape of the projection optical system PL. At this time, the field curvature may be calculated separately from the image plane shape. Here, the measurement marks PM are arranged at a plurality of points where the reticle R should be moved to measure the best focus position. However, a plurality of measurement marks PM are formed on the reticle R, and the movable reticle blind 1 is formed.
The measurement focus PM at each point may be detected by sequentially irradiating each measurement mark PM with the illumination light IL according to 2.

The image plane of the projection optical system PL, that is, the best image forming plane, has an infinite number of points (that is, different points from the optical axis)
Since it is a surface composed of a set of best focus points at so-called countless points having different image heights, the image surface shape can be easily and accurately obtained by such a method.

By the way, as in this embodiment, the photo
When a multiplier tube (PMT, photomultiplier tube) is used as the optical sensor 24, when measuring an aerial image, for example, L / with a duty ratio of 1: 1 is used as a measurement mark.
Even when the S pattern is used, the optical sensor 2
It is desirable to set the signal sensitivity (detection sensitivity) of the signal processing system including the signal processing circuit 4 and its signal processing circuit so that the dynamic range can be effectively used. In particular, when a pseudo-isolated line having a duty ratio of 1: 9 is used as a measurement mark as in the present embodiment, the L / S having a duty ratio of 1: 1 is used.
The adjustment of the signal sensitivity is important because the amplitude of the fundamental wave tends to be smaller than in the case of the pattern and the measurement accuracy is inferior.

Next, a method of setting the signal sensitivity (calibration method) of the signal processing system for processing the signal light (slit transmitted light) performed by the exposure apparatus 100 of the present embodiment will be described.

Generally, the sensitivity of the PMT is set by the applied voltage. That is, assuming that the number of dynodes in the electron multiplying section (dynode section) is n and the applied voltage between the anode and the cathode is V, the current multiplication factor μ corresponding to the sensitivity is substantially proportional to the nth power of the applied voltage V. The sensitivity of the PMT is set so that the anode sensitivity is such that the dynamic range of the subsequent signal processing circuit can be used without waste.

However, in the case of the present embodiment, since the aerial image measurement aims to detect the best focus position,
At the time of measurement, the best focus position is unknown. For this reason, the sensitivity setting requires some contrivance. In other words, the peak level of the intensity signal becomes maximum during the best focus, but since the best focus position is unknown, if the applied voltage is set with a higher peak level, the dynamic range is used as effectively as possible. It is difficult to make full use of the resolution of the / D converter (usually 16 bits). On the other hand, if the applied voltage is set with a low peak level, the possibility of exceeding the dynamic range is high.

Therefore, in exposure apparatus 100 of the present embodiment, main controller 20 performs best focus control based on a light intensity signal (photoelectric conversion signal) obtained in a defocused state (or a state in which the best focus position is unknown). The applied voltage V is set so that the maximum peak value of the signal processing circuit 42 substantially falls within the dynamic range of the signal processing circuit 42. Hereinafter, this will be described specifically.

FIG. 8 is a simplified block diagram showing the configuration of a signal processing system 50 for processing signal light (slit transmitted light).

The signal processing system 50 includes an optical sensor (PM
T) 24 and a signal processing circuit 42 including an amplifier circuit 44 composed of an operational amplifier circuit, a sample holder 46, an A / D converter 48, and the like. A high voltage is applied between the anode and the cathode of the optical sensor 24 from a high voltage power supply 52. The main controller 20 controls the high-voltage power supply 5 based on the output of the A / D converter 48 according to the following principle.
2, the signal sensitivity of the signal processing system 50 is set.

FIGS. 9A to 9C schematically show how the intensity signal of the aerial image of the pseudo isolated line pattern changes according to the focus position. These figures show that the slit width (2D) is sufficiently small (almost infinitesimal).
An example in the case of is shown. FIG. 9A shows the best focus state, and the defocus amount increases in the order of FIGS. 9B and 9C. Since the total amount (integrated light amount) of the signal light (slit transmitted light) should be constant regardless of the defocus amount, in FIGS. 9A to 9C, the area s of each mountain and the total area S should have the same value. Here, since there are five mountains, the integrated light amount S = 5 ×
s. Further, since the signal take-in width corresponds to five pitches, the pitch is 5p, where p is the pitch. 9 (A) to 9
In (C), the average values ave of the signal intensities are equal and constant (5s / 5p = s / p) (FIG. 9D).
reference). Therefore, the applied voltage V is adjusted until the average value of the signal obtained at the unknown focus position reaches the target value.

From FIG. 9A, PEAK = s / w (9), where s = ave × p (10), where the design line width is w.

Therefore, the following equation is established. PEAK = s / w = ave × p / w (11)

That is, the peak value PEAK at the best focus in the case of a pseudo isolated line is converted by the above equation (11) based on the target average value ave. Therefore, by determining the applied voltage V such that the peak value PEAK calculated by the above equation (11) substantially falls within the dynamic range of the signal processing circuit 42, the signal sensitivity of the dynamic range can be effectively utilized. Setting is possible.

However, since the slit actually has a finite width, the above setting is actually used in a special case (for example, when the slit width (0.2 μm) matches the line width). Other than ()) are not considered applicable. If the slit has a finite width, the signal will be dull at the width of the slit. In order to effectively utilize the dynamic range, it is necessary to match the peak value of the dull signal with the peak before dulling. Therefore, a method for matching the signal peak value when the signal is dull to the signal peak value when the slit width is sufficiently small will be described below.

First, the case where the width MARK of the target mark in the scanning direction of the spatial image PM ′ is larger than the width 2D of the slit 22, as shown in FIG. 10A, will be described.

FIG. 10B shows an intensity signal of an aerial image PM ′ having a sufficiently small slit width (small infinity).
0 (C) shows the intensity signal of the aerial image PM ′ when the slit width is 2D finite. In these figures, if both the peak values are PEAK, the area SA can be approximated to the area SB. Therefore, the following equation (12)
Holds. PEAK = SA / MARK = SB / MARK (12)

According to the above equation (12), the integral value of one peak of the photoelectric conversion signal obtained by scanning the slit 22 having a finite width and the width of the spatial image PM ′ of the measurement mark in the scanning direction (design value). Based on the above, the signal peak value when the width of the slit 22 is sufficiently small (when it is almost close to the best focus state) can be calculated. This equation (12) can be regarded as the equation (11) in which s and w are replaced with SB and MARK, respectively, and are substantially equivalent. That is, the peak value PEAK when the slit width is sufficiently small can be calculated by dividing the integral value (area) of one peak of the photoelectric conversion signal by the mark width. Therefore, equation (1)
By determining the applied voltage V such that the peak value PEAK calculated based on 2) substantially falls within the dynamic range of the signal processing circuit 42, it is possible to set the signal sensitivity by effectively utilizing the dynamic range. .

Next, as shown in FIG. 11A, the case where the width of the spatial image PM ′ of the target mark in the scanning direction is smaller than the width 2D of the slit will be described.

FIG. 11B shows an intensity signal of an aerial image PM ′ having a sufficiently small slit width (infinitely small).
1 (C) shows an aerial image P when the slit width 2D is finite.
The intensity signal of M 'is shown. In these figures,
Assuming that both peak values are PEAK, the following equation (13) holds. PEAK = SC / MARK = SD / 2D (13)

According to the above equation (13), based on the integral value of one peak of the photoelectric conversion signal obtained by scanning the slit 22 having a finite width and the slit width 2D, the slit 22
Can be calculated when the width is sufficiently small (when it is almost close to the best focus state). That is, the peak value PEAK when the slit width is sufficiently small can be calculated by dividing the integral value (area) of one peak of the photoelectric conversion signal by the slit width 2D. Therefore, the PEAK calculated based on the equation (13) is the signal processing circuit 4
By determining the applied voltage V so as to substantially fall within the dynamic range of 2, the signal sensitivity can be set while making the most of the dynamic range.

As is clear from the above relationship, the integral value of one peak of the photoelectric conversion signal obtained by scanning the slit 22 having a finite width is determined by the line width (design value) of the aerial image PM ′ of the measurement mark. : Line width of measurement mark x projection magnification) and the value obtained by dividing by the larger dimension of slit width 2D.
It is possible to set the signal sensitivity of the signal processing system 50 so that the dynamic range of the signal processing system 50 can be effectively used as much as possible.

The above-described signal sensitivity (detection sensitivity)
Is applied not only to the case where the PMT is used as an optical sensor, but also to the case where the detection sensitivity of another photoelectric conversion element is set, for example, the case where the gain of an amplifier constituting an output amplifier of the photoelectric conversion element is set. It is possible.

As is clear from the above description, in the present embodiment, the main controller 20 controls the measurement processing device,
A signal sensitivity setting device and a calculation device are configured, and the main control device 20 and the aerial image measurement device 59 configure an optical characteristic measurement device.

As described in detail above, according to the exposure apparatus 100 of the present embodiment, the measurement mark PM is illuminated by the illumination system 10, and the spatial image of the measurement mark PM is projected on the image plane via the projection optical system PL. PM 'is formed. In this state, the main controller 20 uses the aerial image measuring device 59 to
The Z position of the slit plate 90 is changed at a predetermined pitch, and the slit scan aerial image measurement is executed for each Z position. That is, main controller 20 generates aerial image PM ′.
Scans the slit plate 90 so that the slits 22 are relatively scanned with respect to the light, and measures the light intensity distribution corresponding to the aerial image PM ′ based on the photoelectric conversion signal from the optical sensor 24, and The device 20 determines that the area surrounded by the waveform of the photoelectric conversion signal obtained for each Z position of the slit plate 90 by the above measurement and the scanning axis of the slit plate 90 is close to the best focus position of the projection optical system PL. A first area (A or C), and a second area (B or E) indicating that it is far from the best focus position.
The best focus position is calculated using the area ratio (α or γ) of the first region and the second region as an evaluation amount.

For this reason, without performing Fourier transformation or the like on the intensity signal (photoelectric conversion signal) of the aerial image, an area surrounded by the waveform of each of the obtained photoelectric conversion signals and the scanning axis of the slit plate 90 (slit 22) is defined. Only by dividing into two according to the above-mentioned criterion, depending on the area ratio of these two regions, regardless of the type of the measurement mark, that is, L / L of a relatively small repetition period
The best focus position of the projection optical system PL can be measured with high accuracy by using a measurement mark composed of an isolated line and a pseudo isolated line as well as the S mark.

Further, according to the signal sensitivity setting method of the signal processing system 50 performed in the exposure apparatus 100 of the present embodiment, a linear pattern (for example, a predetermined line width extending in the X-axis direction) on the object plane of the projection optical system PL. Measurement mark) Illumination light I via PM
L is irradiated onto the image plane via the projection optical system PL, and the slit 22 having a predetermined width extending in the X-axis direction on the image plane is scanned with the illumination light IL along the Y-axis direction, for example. The illumination light IL passing through the slit 22 is received by the optical sensor 24 and converted into a photoelectric conversion signal corresponding to the intensity of the received light. Then, based on the integrated value of the photoelectric conversion signal, in the direction as described above, the signal processing system 5 is used so that the dynamic range of the signal processing system 50 can be utilized as effectively as possible.
Set a signal sensitivity of 0. As described above, the signal sensitivity is set so that the dynamic range of the signal processing system can be effectively used as much as possible. As a result, the intensity distribution of the illumination light IL at a high resolution. The light intensity distribution corresponding to the image PM ′ can be measured.

Further, according to exposure apparatus 100 of the present embodiment, since slit plate 90 is provided with aerial image measurement device 59 provided integrally with wafer stage WST, main controller 20 uses the aerial image measurement device. Using the device 59, the best focus position of the projection optical system PL can be measured with high accuracy. Then, based on the measurement result of the best focus position, for example, a multipoint focal position detection system (60a,
60b) Output calibration information setting (focus offset setting, so-called focus calibration)
As a result, the optical positional relationship between the reticle R and the wafer W at the time of scanning exposure can be adjusted to a desired positional relationship. Exposure can be realized.

In each of the above embodiments, the case where the present invention is applied to the step-and-scan type projection exposure apparatus has been described. However, the present invention is not limited to this. Transferring the pattern onto the substrate and moving the substrate step by step
The present invention can be applied to an AND-repeat type exposure apparatus.

In each of the above embodiments, the case where the present invention is applied to an exposure apparatus for manufacturing a semiconductor has been described. However, the present invention is not limited to this. For example, a liquid crystal display element pattern is transferred to a square glass plate. The present invention can be widely applied to an exposure apparatus for a liquid crystal, an exposure apparatus for manufacturing a thin film magnetic head, an image sensor, a micromachine, a DNA chip, a reticle, a mask, and the like.

In each of the above embodiments, KrF excimer laser light (248 nm) and ArF
The case where excimer laser light (193 nm) or the like is used has been described.
i-line (365 nm), F ₂ laser light (157 nm), harmonics of a copper vapor laser, a YAG laser, and the like can be used as illumination light for exposure.

In each of the above embodiments, the case where the reduction system and the refraction system are used as the projection optical system has been described. However, the present invention is not limited to this. System, a catadioptric system, or a reflective system may be used.

In addition, the illumination optical system and the projection optical system PL composed of a plurality of lenses are incorporated in the exposure apparatus main body to perform optical adjustment, and the reticle stage RST and the wafer stage WST including a number of mechanical parts are mounted on the exposure apparatus main body. The exposure apparatus 100 of the present embodiment can be manufactured by attaching and connecting wires and pipes, and further performing overall adjustment (electric adjustment, operation confirmation, and the like). It is desirable that the manufacture of the exposure apparatus be performed in a clean room in which the temperature, cleanliness, and the like are controlled.

<< Device Manufacturing Method >> Next, an embodiment of a device manufacturing method using the above-described exposure apparatus 100 in a lithography process will be described.

FIG. 12 shows devices (semiconductor chips such as ICs and LSIs, liquid crystal panels, CCDs, thin-film magnetic heads,
The flowchart of the example of manufacture of a micromachine etc. is shown. As shown in FIG.
In 1 (design step), a function / performance 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 or the like using the mask and the wafer prepared in steps 201 to 203, as described later. . Next, in step 205 (device assembly step), device assembly is performed using the wafer processed in step 204. In this step 205,
Steps such as a dicing step, a bonding step, and a packaging step (chip encapsulation) are included as necessary.

Finally, step 206 (inspection step)
In step S205, inspections such as an operation check test and a durability test of the device created in step 205 are performed. After these steps, the device is completed and shipped.

FIG. 13 shows a detailed flow example of step 204 in the semiconductor device. In FIG. 13, in step 211 (oxidation step), the surface of the wafer is oxidized. Step 212 (CV
In step D), 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 214
In the (ion implantation step), ions are implanted into the wafer. Each of the above steps 211 to 214 constitutes a pre-processing step in each stage of wafer processing, and is selected and executed according to a necessary process in each stage.

In each stage of the wafer process, when the above-mentioned pre-processing step is completed, the post-processing step is executed as follows. In this post-processing step, first, in step 2
In 15 (resist forming step), a photosensitive agent is applied to the wafer. Subsequently, in step 216 (exposure step), the circuit pattern of the mask is transferred onto the wafer by the lithography system (exposure apparatus) and the exposure method described above. Next, in step 218 (etching step), the exposed members other than the portion where the resist remains are 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.

If the device manufacturing method of the present embodiment described above is used, the exposure apparatus of the above embodiment is used in the exposure step (step 216). The reticle pattern can be well transferred onto the wafer. As a result, the productivity (including yield) of highly integrated devices
Can be improved.

[0159]

As described above, according to the optical characteristic measuring method and the optical characteristic measuring apparatus of the present invention, the best focus position of the projection optical system can be measured with high accuracy regardless of the type of the measurement mark. There is an effect that can be.

Further, according to the signal sensitivity setting method of the present invention, there is an effect that the light intensity distribution can be measured with high accuracy by making the best use of the resolution of the signal processing system.

Further, according to the exposure apparatus of the present invention, there is an effect that the occurrence of an exposure defect due to defocus can be suppressed and a highly accurate exposure can be realized.

According to the device manufacturing method of the present invention, there is an effect that the productivity of the device can be improved.

[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 showing an internal configuration of an aerial image measuring device and an alignment microscope of FIG. 1;

FIG. 3 is a diagram illustrating a state where an alignment mark on a wafer is detected by an alignment microscope.

FIG. 4A is a plan view showing an aerial image measuring device in a state where an aerial image PM ′ is formed on a slit plate at the time of aerial image measurement, and FIG. 4B is a plan view of the aerial image measurement. FIG. 7 is a diagram showing an example of a photoelectric conversion signal (light intensity signal) P obtained at that time.

5A and 5B are diagrams for explaining a first method for detecting a best focus position, and FIG. 5A is a graph showing a slit transmitted light intensity in a best focus state obtained as a result of simulation on a horizontal axis. FIG. 5B is a diagram showing the slit transmitted light intensity in a state where the focus is 1 μm defocused, with the horizontal axis as the Y position of the slit.

FIG. 6 is a diagram for explaining a method of obtaining a best focus position using an area ratio as an evaluation amount.

7A and 7B are diagrams for explaining a second method for detecting a best focus position, and FIG. 7A is a graph showing the slit transmitted light intensity in the best focus state obtained as a result of simulation on the horizontal axis. FIG. 7B is a diagram showing the slit transmitted light intensity in the state of 1 μm defocus as the Y position of the slit.

FIG. 8 is a simplified block diagram showing a configuration of a signal processing system for processing signal light (slit transmitted light).

9 (A) to 9 (D) show slit widths (2
FIG. 9 is a diagram for explaining a method of setting signal sensitivity when D) is sufficiently small (almost infinitely small).

FIGS. 10A to 10C illustrate a method of setting the signal sensitivity when the slit width (2D) is finite and the width of the aerial image of the mark is wider than the slit width. FIG.

FIGS. 11A to 11C illustrate a method of setting the signal sensitivity when the slit width (2D) is finite and the width of the aerial image of the mark is smaller than the slit width. FIG.

FIG. 12 is a flowchart illustrating an embodiment of a device manufacturing method according to the present invention.

FIG. 13 is a flowchart showing details of step 204 in FIG.

[Explanation of symbols]

Reference Signs List 10 illumination system (illumination device), 20 main control device (measurement processing device, calculation device, signal sensitivity setting device, part of optical characteristic measurement device), 22 slit (measurement pattern), 24
... Optical sensor (photoelectric conversion element), 42 ... Signal processing circuit, 5
0: signal processing system, 59: aerial image measuring device (part of optical property measuring device), 90: slit plate (pattern forming member),
100: exposure apparatus, PL: projection optical system, IL: illumination light,
PM: measurement mark, PM ': spatial image, W: wafer (substrate), R: reticle (mask), WST: wafer stage (substrate stage).

Continued on the front page (72) Inventor Naoto Kondo 3-2-3 Marunouchi, Chiyoda-ku, Tokyo F-term in Nikon Corporation (reference) 5F046 BA04 BA05 DA14 DB05 EA03 EA12 EA13 EA13 EB03

Claims (18)

[Claims] An optical characteristic measuring method for measuring an optical characteristic of a projection optical system, wherein a predetermined measurement mark is illuminated with illumination light, and a spatial image of the measurement mark is projected on an image plane via the projection optical system. And scanning the measurement pattern disposed on the image plane side of the projection optical system relative to the aerial image, and according to the intensity of the illumination light via the measurement pattern. Obtaining a photoelectric conversion signal at each of a plurality of positions in the optical axis direction of the measurement pattern; and a waveform of the photoelectric conversion signal and the measurement pattern obtained at each position in the optical axis direction of the measurement pattern. A first area indicating that an area surrounded by the scanning axis is close to a best focus position of the projection optical system;
And a second area indicating that the area is far from the best focus position, and detecting the best focus position using an area ratio between the first area and the second area as an evaluation amount; Optical property measurement method including: 2. The method according to claim 1, wherein the photoelectric conversion signal is an image intensity signal representing an intensity of an aerial image corresponding to each position of the measurement pattern, and the first area is an area corresponding to the image intensity signal. The area of a predetermined width including a design best focus position when divided along a direction, and the second area is the remaining area after the division. Optical property measurement method. 3. The photoelectric conversion signal is an image intensity signal representing an intensity of an aerial image corresponding to each position of the measurement pattern, and the first area is a predetermined area corresponding to the image intensity signal. The area on the side closer to the maximum image intensity divided along the intensity direction at the boundary of the image intensity threshold, wherein the second area is the remaining area after the division. The described optical property measurement method. 4. The method according to claim 1, further comprising the step of repeatedly detecting the best focus position with respect to a plurality of points having different distances from the optical axis of the projection optical system, thereby detecting an image plane shape of the projection optical system. Claims 1-3
The optical characteristic measuring method according to any one of the above. 5. The measurement mark according to claim 1, wherein the measurement mark is an isolated linear pattern including at least one line pattern extending in a direction orthogonal to the scanning direction. The described optical property measurement method. 6. The measurement pattern is a slit-shaped opening pattern having a predetermined width extending in a direction orthogonal to the scanning direction in a two-dimensional plane perpendicular to the optical axis. 6. The optical characteristic measuring method according to any one of 5. 7. A photoelectric conversion device that outputs a photoelectric conversion signal according to the intensity of received signal light when obtaining the photoelectric conversion signal, and a processing circuit that receives the photoelectric conversion signal from the photoelectric conversion device. While using a signal processing system,
The dynamic range of the signal processing system is maximized based on a value obtained by dividing the integral value of one peak of the photoelectric conversion signal by the larger dimension of the line width of the measurement mark and the width of the measurement pattern. The signal sensitivity of the signal processing system is set so that it can be used as effectively as possible.
7. The method for measuring optical characteristics according to any one of claims 6 to 6. 8. A signal of a signal processing system including a photoelectric conversion element for outputting a photoelectric conversion signal corresponding to the intensity of a received signal light, and a signal processing circuit to which the photoelectric conversion signal from the photoelectric conversion element is input. A signal sensitivity setting method for setting sensitivity, the method comprising: irradiating illumination light on a second surface via a linear pattern having a predetermined line width extending in a first direction on the first surface; Scanning the measurement pattern having a predetermined width extending in the first direction with respect to the illumination light along a second direction orthogonal to the first direction, and applying the illumination light via the measurement pattern to the measurement pattern. Receiving the light by the photoelectric conversion element and converting the light into a photoelectric conversion signal corresponding to the intensity of the received light; and making the most of the dynamic range of the signal processing system based on the integrated value of the photoelectric conversion signal. So that the signal of the signal processing system Process and for setting the degrees; signal sensitivity setting method comprising. 9. In the setting step, a value obtained by dividing an integral value of one peak of the photoelectric conversion signal waveform by a larger dimension of a line width of the linear pattern and a width of the measurement pattern. 9. The signal sensitivity setting method according to claim 8, wherein the signal sensitivity is set based on the following. 10. The photoelectric conversion device according to claim 8, wherein the photoelectric conversion element is a photomultiplier tube, and the signal sensitivity is set by setting an applied voltage applied to the photomultiplier tube. The signal sensitivity setting method described. 11. An optical characteristic measuring device for measuring an optical characteristic of a projection optical system, wherein the measurement mark is illuminated to form a spatial image of a predetermined measurement mark on an image plane via the projection optical system. A pattern forming member disposed on the image plane side of the projection optical system and having a measurement pattern formed thereon; and outputting a photoelectric conversion signal corresponding to the intensity of the illumination light via the measurement pattern. A photoelectric conversion element; the measurement mark is illuminated by the illumination device, and the measurement pattern is scanned relative to the aerial image in a state where the aerial image is formed on the image plane. While scanning the pattern forming member, the light intensity distribution corresponding to the aerial image is measured for each of the plurality of positions in the optical axis direction of the pattern forming member based on the photoelectric conversion signal from the photoelectric conversion element. An area surrounded by a waveform of the photoelectric conversion signal obtained for each position in the optical axis direction of the pattern forming member as a measurement result of the measurement processing apparatus and a scanning axis of the pattern forming member; An area ratio between the first area and the second area is divided into a first area indicating that the projection optical system is close to the best focus position and a second area indicating that the projection optical system is far from the best focus position. And a calculating device that calculates the best focus position using the evaluation value as an evaluation amount. 12. The optical characteristic measuring apparatus according to claim 11, wherein the measurement mark is an isolated linear pattern composed of at least one line pattern extending in a direction orthogonal to the scanning direction. 13. The slit-like opening pattern having a predetermined width extending in a direction orthogonal to the scanning direction in a two-dimensional plane perpendicular to the optical axis. 13. The optical characteristic measuring device according to item 12. 14. A signal processing circuit for receiving the photoelectric conversion signal constituting a signal processing system having a predetermined dynamic range together with the photoelectric conversion element, wherein the measurement processing device has a signal sensitivity of the signal processing system. The signal sensitivity setting device, when measuring the light intensity distribution corresponding to the aerial image based on the photoelectric conversion signal, based on the integrated value of the photoelectric conversion signal, The signal sensitivity of the signal processing system is set so that the dynamic range of the signal processing system can be effectively used as much as possible.
The optical characteristic measuring device according to any one of claims 13 to 13. 15. The signal sensitivity setting device, based on a value obtained by dividing an integral value of one peak of the photoelectric conversion signal by a larger dimension of a line width of the measurement mark and a width of the measurement pattern. 15. The optical characteristic measuring apparatus according to claim 14, wherein the signal sensitivity is set by setting. 16. The photoelectric conversion element is a photomultiplier tube, and the signal sensitivity setting device sets the signal sensitivity by setting an applied voltage applied to the photomultiplier tube. The optical characteristic measuring device according to claim 14 or 15, wherein 17. An exposure apparatus for transferring a circuit pattern formed on a mask to a substrate via a projection optical system, wherein the substrate stage moves while holding the substrate; An exposure apparatus comprising: the optical characteristic measuring apparatus according to any one of claims 11 to 16 provided integrally; 18. A device manufacturing method including a lithography step, wherein exposure is performed using the exposure apparatus according to claim 17 in the lithography step.