JP2002170754A - Exposure system, method of detecting optical characteristic, and exposure method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make high-accuracy optical measurement possible by simultaneously lightening the influences of the shapes of the moving surface of a stage and the surface of a slit plate having a slit for detection upon measured results. SOLUTION: In an exposure system, a memory 21 storing the data about the surface shape of the slit plate which is set up nearly perpendicular to the optical axis AX (in Z-direction) of an optical system PL is provided on the stage 18. Consequently, at the time of detecting the optical characteristic of the optical system PL by using a detecting system 59, the difference between the Z-position of the slit and the Z- position of a measuring point can be found accurately, based on the measured results of the Z-position of the measuring point and the data about the surface shape of the slit plate, even when any one of points provided on the surface of the slit plate is selected as the measuring point and the Z-position of the selected point is measured by means of measuring instruments (60a and 60b). Therefore, high-accuracy optical measurement becomes possible by simultaneously lightening the influences of the shapes of the moving surface of the stage 18 and the surface of the slit plate upon the measured results by adjusting the Z-position of the slit plate to a prescribed position based on the difference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus, an optical characteristic detecting method and an exposure method, and more particularly, to an exposure apparatus used in a lithography process for manufacturing a semiconductor device (integrated circuit), a liquid crystal display device, and the like. The present invention relates to an optical characteristic detecting method suitable for detecting optical characteristics of a projection optical system in the exposure apparatus, and an exposure method using the optical characteristic detecting method.

[0002]

2. Description of the Related Art Conventionally, in a lithography process for manufacturing a micro device such as a semiconductor device and a liquid crystal display device,
Various exposure apparatuses are used. In recent years, for example, as a semiconductor exposure apparatus, a fine pattern formed on a photomask or a reticle (hereinafter, collectively referred to as a “reticle”) is formed on a substrate such as a semiconductor wafer or a glass plate coated with a photosensitive agent such as a photoresist. (Hereinafter, collectively referred to as “wafer”) via a projection optical system.
Projection exposure apparatuses such as an AND repeat type reduction projection exposure apparatus (so-called stepper) and a step-and-scan type scanning projection exposure apparatus (a so-called scanning stepper) obtained by improving this stepper are mainly used. ing.

In the case of manufacturing a semiconductor device or the like, it is necessary to form different circuit patterns on the substrate in a number of layers, so that the reticle on which the circuit pattern is drawn and each shot area on the wafer are formed. It is important to accurately overlap the pattern already formed on the substrate. In order to perform such superposition accurately, it is essential that the imaging characteristics of the projection optical system be adjusted to a desired state. Further, with the miniaturization of circuit patterns, the exposure apparatus has also been required to have a uniform pattern line width in a shot area. In order to increase the uniformity of the pattern line width, it is assumed that the illuminance distribution on the image plane is uniform.

As a precondition for adjusting the imaging characteristics of the projection optical system, it is necessary to accurately measure the imaging characteristics. Conventionally, as a method of measuring the image forming characteristic, a resist is obtained by performing exposure using a measurement reticle having a predetermined measurement pattern formed thereon and developing a wafer on which a projection image of the measurement pattern is transferred and formed. A method of calculating imaging characteristics based on a measurement result of an image (hereinafter, referred to as a “printing method”) is
It was mainly used. In recent years, a measurement reticle is illuminated with illumination light without actually performing exposure, and a spatial image (projection image) of a measurement pattern formed by a projection optical system is measured. A method of calculating image characteristics (hereinafter, referred to as “aerial image measurement method”) has also been performed.

In the conventional aerial image measurement, for example, an aperture plate having a square aperture is set on a wafer stage, and a spatial image of a measurement pattern on a measurement reticle formed by a projection optical system is compared with a wafer. Relative scanning of the stage,
The illumination light transmitted through the opening is received by the photoelectric conversion element and photoelectrically converted. By subjecting the photoelectric conversion signal to predetermined signal processing, an optical image (spatial image) on which the measurement pattern is projected is obtained. The measurement of the aerial image and the detection of distortion and other optical characteristics of the projection optical system based on the aerial image are disclosed in detail in, for example, Japanese Patent Application Laid-Open No. 10-209031.

Further, the adjustment of the illuminance on the image plane has been performed based on the result of installing an illuminometer on the wafer stage and periodically measuring the illuminance of the image plane with the illuminometer. In addition, the measurement of illuminance unevenness on the image plane is performed by measuring a light quantity sensor (also called an unevenness sensor) having a pinhole-shaped opening (usually formed by removing a part of a reflection film or a transmission film formed on a glass surface). Is mounted on a wafer stage, and the wafer stage is moved in a two-dimensional direction to obtain illuminance non-uniformity based on the in-plane distribution of the intensity of the illumination light that has passed through the projection optical system and received by the non-uniformity sensor through the opening. I was

[0007]

When the aerial image measurement device (projection image detection system) on the wafer stage measures, the positioning of the projection optical system in the optical axis direction (for convenience, "Z axis direction") is performed by exposure. This is performed using an oblique incidence type or other autofocus sensor (AF sensor) provided in the apparatus.
However, even if a multi-point focal position detection system (multi-point AF sensor) having a large number of measurement points, which is disclosed in, for example, Japanese Patent Laid-Open No. A plane (XY) orthogonal to the optical axis of the opening
The position within the plane does not always match the position of the measurement point of the AF sensor. In such a case, a. Prior to the aerial image measurement, after adjusting the relative positional relationship between the aperture and the projection optical system in the Z-axis direction with the position of the aperture in the XY plane coincident with the position of the measurement point of the AF sensor. Moving the wafer stage in the XY plane while maintaining the position in the Z-axis direction at that time to perform aerial image measurement, or b.
The wafer stage is moved to the measurement position in the XY plane, and the relative positional relationship between the opening and the projection optical system in the Z-axis direction is adjusted based on the measurement value of the AF sensor measurement point that can be measured at that position. Either method was adopted.

In the former case, if the moving surface (also called a running surface) of the wafer stage has irregularities, it is affected by the unevenness and the Z position of the opening (that is, the detecting section of the projection image detecting system) is set to a desired value. Could not be set to position. on the other hand,
In the latter case, the Z position of the opening (that is, the detection unit of the projection image detection system) cannot be set to a desired position due to the influence of the surface shape of the opening plate in which the opening is formed. .

In the case of measuring the illuminance unevenness on the image plane by the unevenness sensor, the same inconvenience may occur as described above.

In addition, there is a case where a portable wavefront aberration measuring device is temporarily installed on a wafer stage to measure the wavefront aberration of the projection optical system. In some cases.

The present invention has been made under such circumstances, and a first object of the present invention is to provide a moving surface shape of a substrate stage,
Provided is an exposure apparatus capable of performing highly accurate optical measurement by simultaneously reducing the influence of the surface shape of a plate-like member on which specific components constituting a detection system are arranged on a measurement result. It is in.

A second object of the present invention is to provide an optical characteristic detecting method capable of detecting optical characteristics of a projection optical system with high accuracy.

A third object of the present invention is to provide an exposure method capable of performing exposure with high accuracy.

[0014]

According to the present invention, there is provided an exposure apparatus for transferring a pattern of a mask (R) onto a substrate (W) via a projection optical system (PL). And a specific component (2) disposed on a part of a plate-like member (90) disposed on the substrate stage substantially perpendicular to the optical axis of the projection optical system.
2) at least, a detection system (59) for detecting optical information that changes according to the position of the specific component in the optical axis direction of the projection optical system; and the positional relationship with the projection optical system is fixed; Measuring device (60a, 60b) capable of measuring positional information on the plate-like member surface in the optical axis direction
And a storage device storing shape data of the surface of the plate member obtained based on positional information in the optical axis direction of at least three points on the surface of the plate member measured in advance using the measurement device ( 21) and;

According to this, the detection system including at least a specific component disposed on a part of the plate-like member disposed substantially perpendicularly to the optical axis of the projection optical system on the substrate stage can be used as the specific component. Optical information sensitive to the position of the projection optical system in the optical axis direction is detected. At the time of this detection, the measuring device measures the position information on the surface of the plate member in the optical axis direction. Therefore, no matter which point on the surface of the plate member is measured by the measurement device, the measurement result of the position in the optical axis direction at the measurement point and the surface of the plate member stored in the storage device are measured. Based on the shape data
The position of the specific component in the optical axis direction can be accurately obtained, and the position of the plate member in the optical axis direction can be adjusted to a desired position based on the obtained position. Therefore, by performing this adjustment at the time of detection of the optical information by the detection system, the moving surface shape of the substrate stage, the surface shape of the plate-like member on which specific components constituting the detection system are arranged. However, it is possible to perform highly accurate optical measurement (detection of optical information) by simultaneously reducing the influence on the measurement result.

Here, the "specific component" is a component of the detection system, and includes a component which is provided on the substrate stage and whose position in the optical axis direction changes optical information to be detected. For example, any of a light receiving unit (for example, a photoelectric element), a light emitting unit, and the above-described aperture plate may be used. Of course, the specific component may be the detection system itself.

In this case, the measuring device may be any device as long as it can measure the position information on the surface of the plate-like member in the optical axis direction. For example, it may be a surface shape measuring device such as a Fizeau interferometer. However, as in the second aspect of the present invention, the measuring device may be an oblique incident light type multi-point focal position detecting device (60a, 60b).

The exposure apparatus according to claim 1, wherein
The shape data of the plate-shaped member stored in the storage device is data obtained based on positional information in the optical axis direction of at least three points on the surface of the plate-shaped member measured in advance using a measuring device. The type is not particularly limited. For example, as in the invention according to claim 3, the storage device (90) is calculated based on positional information of the surface of the plate member in the optical axis direction measured in advance using the measuring device. Bispline curved surface data may be stored as shape data of the surface of the plate member. Bispline curved surface data can be obtained based on, for example, positional information of the plate member surface at 16 points in the optical axis direction.

In the exposure apparatus according to each of the first to third aspects of the present invention, as in the fourth aspect of the present invention, the detection system (59) is used at a predetermined point in the field of view of the projection optical system using the detection system (59). While detecting the optical information, the measuring device (6
0a, 60b) based on the shape data stored in the storage device according to the positional relationship between the measurement point (S) and the specific component (22) constituting the detection system. A control device (2) that corrects the position of the plate member in the optical axis direction set by using a measuring device.
0) can be further provided. In such a case, the control device detects optical information at a predetermined point in the field of view of the projection optical system using the detection system. At this time, the control device detects the optical information in a plane orthogonal to the optical axis of the measurement point of the measurement device. The position may not coincide with the position of the specific component configuring the detection system, and the position of the specific component in the optical axis direction may not be set to the expected position. In such a case, the control device sets a plate-like member that is set using the measurement device at the time of detection based on the shape data stored in the storage device in accordance with the positional relationship between the measurement point and the specific component. Is corrected in the optical axis direction. Therefore, the position of the specific component in the optical axis direction can be accurately set to a desired position without being affected by the surface shape of the plate-shaped member. Of course, at the position where optical information is detected at a predetermined point in the field of view of the projection optical system using the detection system, the position of the specific component in the optical axis direction is accurately set to the expected position, so that the substrate stage can be moved. There is no influence of the resulting moving surface shape at all.

In the exposure apparatus according to each of the first to third aspects of the present invention, as in the fifth aspect of the present invention, the optical information is obtained at a predetermined point in the field of view of the projection optical system using the detection system. And detecting the detection result or the detection based on the shape data stored in the storage device according to the positional relationship between the measurement point of the measurement device and the specific component configuring the detection system. The apparatus may further include a control device that corrects position information at the predetermined point in the optical axis direction obtained from the result.

In such a case, the control device detects optical information at a predetermined point in the field of view of the projection optical system using the detection system. At this time, the optical information is orthogonal to the optical axis of the measurement point of the measurement device. The position in the plane may not match the position of the specific component constituting the detection system, and the position of the specific component in the optical axis direction may not be set to the expected position. In such a case, the control device once detects optical information at a predetermined point in the field of view of the projection optical system using the detection system, and then determines the positional relationship between the measurement point of the measurement device and the specific component. In response to the,
Based on the shape data stored in the storage device, a detection result (detection result of optical information) or position information at the predetermined point in the optical axis direction obtained from the detection result is corrected. As a result, the position information in the optical axis direction is appropriately corrected, and an accurate detection result can be obtained. Also in this case, without being affected by the surface shape of the plate-shaped member,
Further, there is no influence of the shape of the moving surface due to the movement of the substrate stage.

In each of the exposure apparatuses according to the first to third aspects, as in the exposure apparatus according to the sixth aspect, the measurement system is different from the measurement point of the measurement apparatus within the field of view of the projection optical system using the detection system. While detecting the optical information at a predetermined point, calibration of the measurement device with respect to the measurement point based on the shape data stored in the storage device and position information on the optical axis direction obtained from the detection result The information processing apparatus may further include a control device that determines information.

In the exposure apparatus according to each of the first to sixth aspects of the present invention, the detection system may be a detection system that detects optical information that changes according to the position of the specific component in the direction of the optical axis of the projection optical system. For example, the detection system may be a projection image detection system that detects a projection image projected by the projection optical system. In such a case, the projection image can be accurately detected without being affected by the surface shape of the plate-like member, and without being affected by the movement surface shape caused by the movement of the substrate stage.

In each of the exposure apparatuses according to the first to fourth aspects, the detection system is used for detecting aberration information (for example, wavefront aberration) of the projection optical system, and is provided on a predetermined surface orthogonal to the optical axis. Thus, the amount of deviation of the projection image formed by the projection optical system from the reference position can be detected. In each of the exposure apparatuses according to the first to fifth aspects, the detection system may detect the illuminance at the predetermined point as the optical information.

According to an eighth aspect of the present invention, there is provided a projection optical system (P) for projecting a pattern arranged on a first surface onto a second surface.
An optical characteristic detecting method for detecting the optical characteristic of L),
A first method for obtaining shape data of a surface of a plate-like member (90) which is disposed substantially perpendicular to the optical axis of the projection optical system and partially provided with a detection unit (22) of a detection system (59) for detecting optical information. Measuring the position information of the surface of the plate member in the optical axis direction at a specific measurement point of a measuring device (60a, 60b) for measuring the position information of the surface of the plate member in the optical axis direction; The measurement result and the positional relationship between the specific measurement point and the detection unit at the time of measurement, and the optical axis direction of the plate-like member set using the measurement device based on the obtained shape data. A second step of detecting, using the detection system, optical information that changes in accordance with the position of the detection unit with respect to the optical axis direction, in a state where the position regarding the optical information is corrected; and Projection optical system Including; a third step of calculating the optical properties.

According to this, prior to the detection of the optical information, the surface of the plate-like member is disposed substantially perpendicular to the optical axis of the projection optical system and partially has a detection section of the detection system for detecting the optical information formed therein. Is obtained. Next, position information about the optical axis direction of the surface of the plate member at a specific measurement point of the measuring device that measures the position of the surface of the plate member in the optical axis direction of the projection optical system is measured, and the measurement result and the identification at the time of measurement are measured. Based on the positional relationship between the measurement point and the detection unit, and the position in the optical axis direction of the plate-like member set using the measurement device, based on the shape data previously obtained, the detection system is The optical information that changes according to the position of the detection unit in the optical axis direction is detected. For this reason, the position of the detection unit in the optical axis direction can be accurately set to a desired position without being affected by the surface shape of the plate member. In this case, unlike the case where the optical member is moved in a plane perpendicular to the optical axis to detect optical information after setting the position of the detection unit in the optical axis direction to a desired position, There is no influence from the shape of the moving surface due to the movement in the plane perpendicular to the axis. Therefore, optical information can be accurately detected. Then, since the optical characteristics of the projection optical system are calculated based on the detection result of the optical information, the optical characteristics of the projection optical system can be detected with high accuracy.

According to a ninth aspect of the present invention, there is provided a projection optical system (P) for projecting a pattern arranged on a first surface onto a second surface.
An optical characteristic detecting method for detecting the optical characteristic of L),
A first method for obtaining shape data of a surface of a plate-like member (90) which is disposed substantially perpendicular to the optical axis of the projection optical system and partially provided with a detection unit (22) of a detection system (59) for detecting optical information. And measuring the position information of the surface of the plate member in the optical axis direction using a measuring device that measures the position information of the surface of the plate member in the optical axis direction, and based on the measurement result, A second step of detecting optical information that changes according to the position of the detection unit in the optical axis direction using the detection system in a state where the position of the member in the optical axis direction is set; The positional relationship between the specific measurement point of the measurement device and the detection unit, and the detected optical information based on the obtained shape data,
Or a third step of correcting the position information in the optical axis direction included in the optical information to determine the optical characteristics of the projection optical system.

According to this, prior to the detection of the optical information, the surface of the plate-like member which is disposed substantially perpendicular to the optical axis of the projection optical system and partially provided with a detection section of the detection system for detecting the optical information is provided. Shape data is required. Next, position information about the optical axis direction of the plate member surface is measured using a measuring device that measures position information about the optical axis direction of the plate member surface, and the position information about the optical axis direction of the plate member is based on the measurement result. With the position set, optical information that changes according to the position of the detection unit in the optical axis direction is detected using the detection system. Then, the positional relationship between the specific measuring point of the measuring device and the detecting unit at the time of detection, and optical information detected based on the obtained shape data, or positional information in the optical axis direction included in the optical information Is corrected to determine the optical characteristics of the projection optical system. As described above, in the present invention, the optical characteristics of the projection optical system are determined by correcting the detected optical information or the positional information in the optical axis direction included in the optical information, thereby determining the optical characteristics of the projection optical system. It is possible to detect with high accuracy. In this case as well, there is no influence from the surface shape of the plate-like member, and no influence from the movement surface shape caused by the movement of the plate-like member.

In each of the optical characteristic detecting methods according to the eighth and ninth aspects, as in the optical characteristic detecting method according to the tenth aspect, the detecting unit is set at a predetermined point in the field of view of the projection optical system. The optical characteristics of the projection optical system at the predetermined point can be calculated by detecting the optical information while changing the position of the plate member in the optical axis direction using the measurement device. .

In each of the optical characteristic detecting methods according to the eighth to tenth aspects, as in the optical characteristic detecting method according to the eleventh aspect, the measuring device includes a plurality of measuring points each corresponding to the plate in the optical axis direction. The position information of the shaped member can be measured, and the specific measurement point can be a measurement point located at a position closest to the detection unit when the optical information is detected.

In each of the optical characteristic detecting methods according to the eighth to eleventh aspects, any method may be used for the measurement of the surface shape of the plate member performed prior to the detection of the projected image. In the first step, the plate member is moved to a position directly below the projection optical system, and at least three of the surface of the plate member moved to a position directly below the projection optical system in the first step. The position information of the projection optical system in the optical axis direction at a point may be measured using the measurement device, and thereafter, the shape data of the surface of the plate member may be calculated based on the measurement result. In addition, Claim 8-
The optical characteristics in each invention described in 11 include, for example, a focal position, aberration, illuminance, and the like.

According to a thirteenth aspect of the present invention, there is provided an exposure method for transferring a pattern of a mask onto a substrate via a projection optical system. Detecting an optical characteristic of the projection optical system using the optical characteristic detection method of the above; and taking into account the detected optical characteristic, an image of the mask pattern projected by the projection optical system and the substrate. Transferring the mask pattern while adjusting the relative position.

According to this method, the optical characteristics of the projection optical system are detected with high accuracy by the respective optical characteristic detection methods according to claims 8 to 12, and thereafter, the projection is performed in consideration of the detected optical characteristics. The transfer of the mask pattern is performed in a state where the relative position between the image of the mask pattern projected by the optical system and the substrate is adjusted. Accordingly, it is possible to suppress the relative positional deviation (alignment error in a broad sense) between the image of the mask pattern and the substrate due to the optical characteristics of the projection optical system, and perform exposure with good overlay accuracy.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS << First Embodiment >> A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a schematic configuration of an exposure apparatus 100 according to the first embodiment. This exposure apparatus 1
Reference numeral 00 denotes a step-and-scan type scanning projection exposure apparatus, that is, a so-called scanning stepper.

The exposure apparatus 100 includes an illumination system 10 including a light source and an illumination optical system, a reticle stage RST for holding a reticle R as a mask, a projection optical system PL, and a wafer W as a substrate. It is provided with a freely movable wafer stage WST and a control system for controlling these.

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, a KrF excimer laser beam (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. 3) having a variable opening. The fixed reticle blind is arranged in the vicinity of the pattern surface of the reticle R or on a surface slightly defocused from its conjugate surface, and has a rectangular opening defining a rectangular slit-shaped illumination area IAR on the reticle R. In addition, movable reticle blind 1
Numeral 2 is disposed on a conjugate plane with respect to the pattern surface of the reticle R, and is a scanning direction at the time of scanning exposure (here, the Y-axis direction which is a direction orthogonal to the paper surface in FIG. 1) and a non-scanning direction (the horizontal direction in the paper surface in FIG. 1). (In the X-axis direction). However, in FIG. 3, for simplicity of explanation, the movable reticle blind 12 is shown as being disposed 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 a 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, and is illuminated on a reticle R on which a circuit pattern or the like is drawn (a rectangular slit elongated in the X-axis direction and having a predetermined width in the Y-axis direction). Illumination area) The IAR is illuminated with uniform illuminance.

The movable reticle blind 12 is controlled by a main controller 20 to be described later at the start and end of the scanning exposure so as to further limit the illumination area IAR so as to prevent unnecessary portions from being exposed. Has become. In the present embodiment, the movable reticle blind 1
2 is also used for setting an illumination area at the time of aerial image measurement by the aerial image measuring device described later.

On the reticle stage RST, a reticle R is fixed, for example, by 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, in the Y-axis direction perpendicular to the X-axis direction, and in the rotation direction (θz direction) around the Z-axis perpendicular to the XY plane), and on a reticle base (not shown). Can be moved in the Y-axis direction at a designated scanning speed. 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
A movable mirror 15 for reflecting the laser beam from the reticle stage RST is fixed, and the position of the reticle stage RST in the XY plane is constantly detected by the reticle interferometer 13 with a resolution of, for example, about 0.5 to 1 nm. Here, actually, a movable mirror having a reflecting surface orthogonal to the scanning direction (Y-axis direction) at the time of scanning exposure on the reticle stage RST and a non-scanning direction (X
A reticle interferometer 13 having at least two axes in the Y-axis direction.
Although at least one axis is provided in the X-axis direction, 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 as a control device comprising a workstation (or a microcomputer), and the main controller 20 converts the position information of the reticle stage RST into position information. The reticle stage RST is driven and controlled via a reticle stage driving system based on the reticle stage.

The projection optical system PL is arranged below the reticle stage RST in FIG. 1 and its optical axis AX is in the Z-axis direction. Here, it is a reduction system that is telecentric 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
The illumination light IL that has passed through the projection optical system PL is projected onto the wafer W, and a reduced image (partially inverted image) of the circuit pattern of the reticle R present in the slit-shaped illumination area IAR is formed by photoresist on the surface. An exposure area IA conjugate to the illumination area IAR on the coated wafer W is formed.

The wafer stage WST includes an XY stage 14 driven in a two-dimensional XY plane by a drive system such as a linear motor or a planar motor along the upper surface of the stage base 16, and a Z · Z (not shown) on the XY stage 14. It has a wafer table 18 as a substrate stage mounted via a tilt drive mechanism, and a wafer holder 25 fixed on the wafer table 18. In this case, the wafer W is held by the wafer holder 25 by vacuum suction (or electrostatic suction). The wafer table 18 is moved in three directions of freedom by a Z-tilt drive mechanism including a voice coil motor and the like in a Z-axis direction, a rotation direction around the X-axis (θx direction), and a rotation direction around the Y-axis (θy direction). It is designed to be driven minutely.

On the wafer table 18, a movable mirror 27 for reflecting a laser beam from a wafer laser interferometer (hereinafter, referred to as a "wafer interferometer") 31 is fixed. The position in the XY plane of wafer table 18 (that is, wafer stage WST) is constantly detected at a resolution of, for example, about 0.5 to 1 nm.

Actually, as shown in FIG. 2, the movable mirror 27Y having a reflecting surface orthogonal to the Y-axis direction, which is the scanning direction at the time of scanning exposure, is placed on the wafer table 18 in the non-scanning direction. A movable mirror 27X having a reflection surface orthogonal to the X-axis direction is provided, and the wafer interferometer 31 is provided in two axes in the X-axis direction and the Y-axis direction, respectively. The moving mirror 27 and the wafer interferometer 31 are shown. Here, in FIG. 2, the moving mirror 27Y
The length measurement axes WIY1 and WIY2 typically shown by two interferometer beams projected perpendicular to the optical axis respectively pass through the optical axis of the projection optical system PL and the detection center of an alignment system ALG described later. A measurement axis WIX1 typically represented by an X-axis interferometer beam projected perpendicularly to a movable mirror 27X.
Intersects perpendicularly with the length measurement axis WIY1 at the optical axis center of the projection optical system PL. Further, X projected vertically to the movable mirror 27X
Measurement axis WIX, typically represented by an axial interferometer beam
Numeral 2 is a detection center of an alignment system ALG described later and vertically intersects with the length measurement axis WIY2. In the present embodiment, the position information of the wafer table 18 at the time of exposure includes the length measurement axes WIY1,
Measured by an interferometer indicated by WIX1, respectively.
Wafer table 18 for alignment and wafer exchange
Is measured by interferometers indicated by the length measurement axes WIY2 and WIX2, and the position of the wafer table 18 can be accurately determined without any so-called Abbe error during both exposure and alignment. It can measure well.

The position information (or speed information) of the wafer table 18 (wafer stage WST) measured by the wafer interferometer 31 is sent to the main controller 20. The main controller 20 adds the position information (or speed information). Wafer stage WST (XY stage 1)
4) The position in the XY plane is controlled.

As shown in FIG. 1, the wafer table 18 is provided with an aerial image measuring device 59 as a detection system (and a projection image detection system) used for measuring the optical characteristics of the projection optical system PL. ing. As shown in FIG. 3, the aerial image measuring device 59 is provided at a protruding portion 58 a having an open top provided on the upper surface of one end of the wafer table 18. The aerial image measuring instrument 59 is formed on the upper surface of the light-receiving glass 82 having a rectangular shape in a plan view, which is fitted from above in a state of closing the opening of the protruding portion 58a,
A reflection film 83 also serving as a light-shielding film in which a slit 22 as a substantially square detection unit is formed at a part thereof, and lenses 84 and 8 disposed inside the wafer table 18 below the slit 22.
6, a relay optical system (84, 8)
6) a bending mirror 88 (here, a light receiving optical system is constituted by the lenses 84, 86 and the mirror 88) for bending the optical path of the illumination light beam (image light beam) relayed by a predetermined optical path length, and a photoelectric conversion element 24 and the like.

Here, as the 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. In addition, as the photoelectric conversion element 24, a light receiving element that can detect weak light with high accuracy, for example, a photomultiplier or the like is used. In the present embodiment, the light receiving glass 82 and the reflection film 83 form a slit plate as a plate-like member. In the following description, the light receiving glass 82 and the reflection film 8
3 is referred to as a “slit plate 90” as appropriate. Further, as described above, the slit 22 is formed in the reflective film 83, but hereinafter, the description will be made assuming that the slit 22 is formed in the slit plate 90 for convenience. Note that the slit plate 90 has a size such that at least three of a plurality of detection points of a multi-point focal position detection system to be described later are simultaneously applied, and the surface shape thereof is determined by the multi-point focal position detection system. Those having a flatness that has a shape change that is sufficiently gradual as compared with the arrangement of points are used.

In the present embodiment, when measuring a projection image (aerial image) of the measurement pattern via the projection optical system PL, which will be described later, the illumination image IL transmitted through the projection optical system PL is used to measure the spatial image. When the slit plate 90 constituting the light source 59 is illuminated, the illumination light IL transmitted through the slit 22 on the slit plate 90 is received by the photoelectric conversion element 24 via the light receiving optical system (84, 86, 88). The photoelectric conversion element 2
4 to a photoelectric conversion signal (light amount signal) P corresponding to the amount of received light.
Is output to the main controller 20.

It is not always necessary to provide photoelectric conversion element 24 inside wafer stage WST.
Photoelectric conversion element 24 may be arranged outside wafer stage WST. In this case, a light transmission optical system that guides the illumination light IL transmitted through the slit 22 to a photoelectric conversion element outside the wafer stage may be configured using a relay optical system, an optical fiber, or the like.

The aerial image measuring method (projected image detecting method) performed by using the aerial image measuring device 59 and a method for measuring the optical characteristics of the projection optical system will be described later.

Returning to FIG. 1, on the side of the projection optical system PL,
Alignment mark (alignment mark) on wafer W
Off-axis alignment system ALG for detecting the In the present embodiment, the alignment system AL
As G, an alignment sensor of an image processing method, that is, an alignment sensor of a so-called FIA (Field Image Alignment) system is used. In this alignment system ALG, the wafer W is irradiated with broadband light (alignment light) from a light source such as a halogen lamp via an illumination optical system.
The upper alignment mark is illuminated, and reflected light from the alignment mark portion is received by an imaging device such as a CCD via an imaging optical system. Thus, a bright field image of the alignment mark is formed on the light receiving surface of the image sensor. A photoelectric conversion signal corresponding to the bright-field image, that is, a light intensity signal corresponding to a reflection image of the alignment mark is supplied to the main controller 20 from the image sensor. Main controller 20 calculates the position of the alignment mark with reference to the detection center of alignment system ALG based on the light intensity signal, and calculates the calculation result and wafer stage WST which is the output of wafer interferometer 31 at that time. Based on your location information
The coordinate position of the alignment mark in the stage coordinate system defined by the optical axis of the wafer interferometer 31 is calculated.

Further, in the exposure apparatus 100 of the present 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 many pinholes or slits toward an imaging surface of projection optical system PL. An oblique incident light type multi-point system including an irradiation optical system 60a for irradiating the FB obliquely with respect to the optical axis AX, and a light receiving optical system 60b for receiving the reflected light flux of the imaging light flux on the surface of the wafer W. A focus position detection system is provided. The multi-point focal position detection system (60a, 60
As b), one having the same configuration as that disclosed in, for example, JP-A-6-283403 is used.

In this case, 49 slit-shaped opening patterns are formed in a matrix arrangement of 7 rows and 7 columns on a pattern forming plate (not shown) constituting the irradiation optical system 60a. For this reason, a rectangular exposure region IA having a predetermined area AS (AS is, for example, 25 mm × about 10 mm) on the surface of the wafer W.
In the vicinity, as shown in FIG. 4, a 7 × 7 matrix arrangement of 7 rows and 7 columns, a total of 49 images of a slit-shaped opening pattern inclined at 45 degrees to the X-axis and the Y-axis (slit) Image) S _{1.1 to} S _7,7 are, for example, 3.3 along the X-axis direction.
They are formed at intervals of mm, for example, at intervals of 4 mm along the Y-axis direction.

The light receiving device (not shown) constituting the light receiving optical system 60b has a 7 × 7 matrix in a 7 × 7 matrix arrangement.
A light receiving slit plate in which a total of 49 slits are formed, and 49 photosensors (for convenience, “photosensors D _{1.1 to} D _{7, 7} "). When the slit images S _{1.1 to} S _7,7 shown in FIG. 4 are respectively re-imaged on the respective slits of the light receiving slit plate, the image light flux of the slit image is received by the photo sensors D _{1.1 to} D _7,7 . It is possible. In this case, in the light receiving optical system 60b,
A rotation direction vibration plate is provided, and the position of each re-formed image is vibrated in a direction orthogonal to the longitudinal direction of each slit on the light receiving slit plate via the rotation direction vibration plate. The detection signals of _{1.1 to} D _7,7 are selectively detected synchronously by the signal selection processing device 40 using the signal of the rotational vibration frequency. Then, a predetermined number n of focus signals obtained by synchronous detection by the signal selection processing device are supplied to the main control device 20. here,
The predetermined number n is determined according to the number of channels of the signal processing circuit in the signal selection processing device 40, and n is 12, for example.

As is clear from the above description, in the present embodiment, the slit images S _1.1 to S _1.1 which are detection points on the wafer W are used.
Each of S _7,7 corresponds to one of the photo sensors D _{1.1 to} D _7,7, and information (focus information) of the Z position on the wafer surface at the position of each slit image is output from each of the photo sensors D. Is obtained based on the defocus signal, which is hereinafter referred to as the slit images S _{1.1 to} S _7,7 for convenience of explanation.
Is referred to as a focus sensor unless otherwise required.

In the main controller 20, for example, at the time of scanning exposure, which will be described later, for example, the defocus signal from the light receiving optical system 60b (defocus signal), for example, 3 so that the defocus becomes zero based on the S-curve signal. Movement of the wafer table 18 in the Z-axis direction via two actuators (not shown),
And two-dimensionally inclined (ie, rotation in θx and θy directions)
, That is, the multipoint focal position detection system (60a, 6
0b) to control the movement of the wafer table 18 to substantially move the image plane of the projection optical system PL and the surface of the wafer W 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 to match.

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

First, a reticle R is transported by a reticle transport system (not shown), and is held by suction at a reticle stage RST at a 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. 3), and the projection position of the reticle pattern image is obtained. That is, reticle alignment is performed.

Next, main controller 20 causes slit plate 90 constituting aerial image measuring instrument 59 to be aligned with alignment system AL.
Wafer stage WST is moved so as to be located immediately below G, and slit 22 serving as a position reference of aerial image measuring device 59 is detected by alignment optical system ALG. 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. AL
The relative position with respect to G, that is, the 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. In this wafer alignment, a wafer alignment mark of a predetermined sample shot of a plurality of shot areas on the wafer W is measured using the alignment system ALG as described above.

Then, main controller 20 monitors the wafer stage WST while monitoring the position information from interferometers 31 and 13 based on the position information and the baseline amount of each shot area on wafer W obtained above. At the scanning start position for the exposure of the first shot area,
The reticle stage RST is positioned at a 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 direction opposite to the Y-axis direction, and when both stages RST and WST reach their respective target scanning speeds, illumination light IL 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 is 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. Blocking the irradiation of the illumination light IL to the outside of the pattern area on the reticle R can be achieved by ordinary scanning and
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 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 surface of the wafer W and the projection optical system PL
The main controller 20 measures the distance between the wafer surface WST and the projection optical system PL and the parallelism between the wafer WST and the projection optical system PL. Is controlled.

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 superimposed during the above-mentioned scanning exposure, the optical characteristics of the projection optical system PL (imaging) It is important that the characteristics (including the characteristics) and the baseline amount are accurately measured, and if possible, that the optical characteristics of the projection optical system PL are adjusted to a desired state.

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

FIG. 3 shows a state in which the aerial image of the measurement pattern formed on the reticle R is being measured using the aerial image measuring device 59. As the reticle R, a reticle R dedicated to aerial image measurement or a device reticle used for manufacturing a device in which a dedicated measurement pattern is formed is used. Instead of these reticles, a fixed mark plate (also called a reticle fiducial mark plate) made of the same glass material as the reticle is provided on the reticle stage RST, and a measurement pattern (measurement pattern) is provided on the mark plate. The formed one may be used. In the following description, the term “reticle for measurement” will be appropriately used as a generic term for the above-described reticle dedicated to aerial image measurement, a device reticle having a dedicated measurement pattern formed thereon, and a reticle fiducial mark plate.

Here, as shown in FIG. 3, the measurement reticle R has a measurement pattern P composed of a line and space mark having a periodicity in the X-axis direction at a predetermined position.
It is assumed that M is formed. In addition, the aerial image measuring device 5
As shown in FIG. 5A, the slit plate 90 of FIG. 9 has a square slit 22 formed therein. In the following, the line and space will be referred to as "L
/ S ".

In measuring the aerial image, the movable reticle blind 12 is driven by the main controller 20 via a blind driving device (not shown), so that the illumination area of the illumination light IL of the measurement reticle R is only the measurement pattern PM portion. (See FIG. 3). In this state, when illumination light IL is applied to reticle R, light (illumination light IL) diffracted and scattered by measurement pattern PM is refracted by projection optical system PL, as shown in FIG. A spatial image (projection image) PM ′ of the measurement pattern PM is formed on the image plane of the optical system PL. At this time, the wafer table 18 (wafer stage WST) places the aerial image P on the + X side (or -X side) of the slit 22 on the slit plate 90 of the aerial image measuring device 59.
It is assumed that M ′ is set at a position where it is formed. FIG. 5A is a plan view of the aerial image measuring instrument 59 at this time.

When main controller 20 drives wafer stage WST through the drive system in the + X direction as shown by arrow A in FIG.
Are scanned in the X-axis direction with respect to the aerial image PM ′. During this scanning, the light (illumination light IL) passing through the slit 22 is received by the photoelectric conversion element 24 via the light receiving optical system in the wafer stage WST, and the photoelectric conversion signal is transmitted to the main controller 20.
Supplied to In this case, for example, a photoelectric conversion signal (a light intensity signal corresponding to an aerial image) as shown in FIG.
Is obtained.

The main controller 20 differentiates the waveform of the photoelectric conversion signal as shown in FIG. 5B with respect to the scanning direction (X-axis direction) to differentiate as shown in FIG. 5C. Find the waveform. Then, a known signal processing such as a Fourier transform method is performed based on the differential waveform as shown in FIG. 5C, and a light intensity distribution corresponding to the aerial image PM ′ on which the measurement pattern is projected is obtained. Ask.

In the following description, the method of measuring an aerial image as described above is called a slit scan method.

When the aerial image measuring device 59 is used, by using various measurement reticles on which various measurement patterns are formed, in addition to the above-described baseline measurement, detection of a best focus position, detection of a pattern image, and the like. Can be detected. The detection of the best focus position is performed for the purpose of measuring optical characteristics such as the best focus position, the best image plane (image plane) position, and spherical aberration of the projection optical system. The detection of the image forming position of the pattern image in the XY plane is performed not only for measuring optical characteristics such as magnification, distortion, and coma of the projection optical system, but also for measuring illumination telecentricity.

Here, a method for measuring various optical characteristics using the aerial image measuring device 59 will be described.

As a premise, it is assumed that the slit plate 90 of the aerial image measuring device 59 has a slit 22 of about 25 μm square as an example.

The detection of the best focus position can be performed as follows.

That is, the best focus position should be measured within the field of view of the projection optical system PL using a measurement reticle in which an L / S mark having a line width of several μm and a duty ratio of 50% is formed as a measurement pattern. The mark PM is positioned on the optical axis of the projection optical system at a fixed point (here, on the optical axis of the projection optical system PL), and the position of the wafer table 18 in the Z-axis direction (hereinafter also referred to as “Z position” as appropriate). The aerial image measurement of the mark PM is repeatedly performed while changing in a predetermined step. Then, the light intensity signal obtained at each Z position is Fourier-transformed and separated into frequency components. For example, the amplitude ratio between the primary frequency component and the zero-order frequency component, that is, (primary / 0
The Z position where the contrast, which is the amplitude ratio of the following), becomes maximum can be obtained as the best focus position.

The detection of the image plane position (image plane shape) can be performed as follows.

That is, the measurement reticle PM is sequentially arranged at each of a plurality of points in the field of view of the projection optical system PL, and the movable reticle is illuminated such that the illumination light IL is applied only to a predetermined area including the measurement pattern PM at each point. The blind 12 limits its illumination area. Then, the above-described best focus position is detected for each point, and the image plane shape of the projection optical system PL can be calculated by performing, for example, statistical processing based on the obtained best focus positions. . At this time, the field curvature may be calculated separately from the image plane shape. Here, the measurement reticle is moved and the measurement pattern PM is arranged at each of a plurality of points where the best focus position is to be measured. However, a plurality of measurement patterns PM are formed on the measurement reticle. Each measurement pattern PM may be sequentially irradiated with the illumination light IL by the movable reticle blind 12 to detect the best focus position at each point.

As the measurement pattern PM, two L / Ss arranged at the same pitch in the X-axis direction (or sagittal direction) and the Y-axis direction (meridional direction) are used.
Using the pattern, the two L / S patterns are sequentially irradiated with the illumination light IL at predetermined points in the field of view of the projection optical system PL and the above-described best focus position is detected, whereby the astigmatism of the projection optical system PL is detected. Can also be measured.

The detection of spherical aberration can be performed as follows.

More specifically, for example, a plurality of, for example, two L / S marks in the X-axis direction having the same line width and different periods at a predetermined distance in the Y-axis direction. Using a measurement reticle in which a first L / S pattern in the axial direction and a second L / S pattern in the X-axis direction having a line width of 1 μm and a period of 4 μm in the X-axis direction are formed as measurement patterns, One of the measurement patterns, for example, the first L / S pattern is positioned on the optical axis of the projection optical system. Then, an illumination area is set only in the vicinity of the first L / S pattern positioned on the optical axis, and the above-described best focus position is detected for the first L / S pattern. When the detection of the best focus position of the first L / S pattern ends, the second L
The measurement reticle is moved to a position where the / S pattern is illuminated by the illumination light, and the above-described best focus position is detected for the second L / S pattern. Then, spherical aberration can be obtained by performing a predetermined calculation based on the difference between the best focus positions for each measurement pattern obtained in this way.

The detection of the magnification and distortion of the projection optical system PL can be performed as follows.

That is, when measuring the magnification and distortion of the projection optical system PL, for example, 150 μm
A square pattern with a corner (30 μm square on the wafer surface at a projection magnification of 1/5) or a large L / S pattern that is hardly affected by coma aberration, for example, an L / S pattern with a line width of 5 μm or more ( This aerial image is an L / S pattern image having a line width of 1 μm) as the measurement pattern PM, and the measurement patterns PM are sequentially arranged at a plurality of points in the field of view of the projection optical system PL, and measurement is performed at each point. The movable reticle blind 12 limits the illumination area so that only a predetermined area including the use pattern PM is irradiated with the illumination light IL. The aerial image measurement is performed for each point by the above-described slit scan method, and the projection optics is determined based on the image formation positions (the X-axis direction and the Y-axis direction) of the measurement pattern at each obtained point. At least one of the magnification and distortion of the system PL can be calculated.

Also, coma aberration is measured by using a measurement reticle on which a measurement pattern suitable for the measurement, for example, a so-called Line in Box pattern is formed.
It can be obtained by measuring the spatial image of the pattern by the slit scan method and performing a predetermined calculation based on the difference between the absolute positions (image positions) of the spatial image between the thick line and the thin line. The illumination telecentric (telecentricity of the projection optical system PL) uses a measurement reticle on which a large measurement pattern not affected by coma aberration is formed.
It can be obtained by measuring the aerial image of the measurement pattern by the slit scan method while changing the Z position, and measuring the absolute position (imaging position) of the aerial image for each focus position.

In detecting each measurement pattern performed when detecting the optical characteristics of the projection optical system described above, it is necessary to move the wafer table 18 stepwise at a predetermined pitch in the Z-axis direction. Main controller 2
In the case of 0, the Z-position of the substrate table is feedback-controlled while monitoring the detection result of the multipoint focus position detection system (60a, 60b) so that the Z-position of the slit 22 portion of the slit plate 90 matches the value to be set. (Servo control). In this case, a multi-point focal position detection system (60a, 60b)
If focus any of the sensors S _1.1 to S _{7, 7} always coincides with the position of the slit 22 of the slit plate 90 (i.e. incident position of one of the imaging light beam FB coincides on the slit 22) of the of, It is possible to detect the best focus position with high accuracy and calculate the optical characteristics based on the detection.

However, this is not always the case, as described above (see FIG. 2). Therefore,
The exposure apparatus of the present embodiment adopts a control algorithm as shown in the flowchart of FIG.
It is possible to detect the best focus position with high accuracy and calculate the optical characteristics of the projection optical system based on this. Of course,
Based on the detected best focus position, the focus calibration of the multipoint focus position detection system (60a, 60b) can be performed with high accuracy.

FIG. 6 is a flowchart showing a control algorithm of main controller 20 when measuring the image plane shape as an example of the optical characteristics of projection optical system PL. Hereinafter, the projection optical system PL by the main controller 20 will be described with reference to FIG.
The operation of measuring the image plane shape will be described.

As a premise, a reticle loader (not shown) loads a measurement reticle (hereinafter referred to as “reticle R1” for convenience) on the reticle stage RST, and a measurement existing at the center of the reticle R1. It is assumed that reticle stage RST has been moved to a position where the pattern for use substantially coincides with the optical axis of projection optical system PL.

First, in step 102, the slit plate 9
0 denotes at least 16 of the focus sensors S _{1.1 to} S _7,7 of the multi-point focal position detection system (60a, 60b) including, for example, a total of 16 focus sensors arranged in a matrix of arbitrary 4 rows and 4 columns The wafer stage WST is moved to a position (slit plate shape measurement position) where the focus sensor S is simultaneously applied to the slit plate 90 via the stage driving system.
Is moved in the XY plane.

In the next step 104, the at least 16 focus sensors S _{i, j} (i = i-1, i, i + 1, i +) of the multipoint focal position detection system (60a, 60b)
2,..., J = j−1, j, j + 1, j + 2,...), And the measured value Z _{i, j} of each focus sensor S is stored in the memory 21 as a storage device.

In the next step 106, the slit plate 90
Is calculated as follows. That is, using a combination of the measured values Z _{i, j of} each focus sensor S _{i, j} and the XY coordinates of each focus sensor, a bicubic bispline curved surface is created, and the expression of each area is expressed by the expression of the slit plate. It is stored in the memory 21 as shape data (original data).

Here, a method of calculating a bicubic bispline surface will be briefly described with reference to FIG.

For generating a bicubic bispline surface,
Consider a net consisting of 16 vertices as shown in FIG. Q _{i, j} is a three-dimensional vector composed of the measurement result of the position of the focus sensor S (imaging light beam FB incident position) and the Z position (called a curved surface definition vector). Generation of a bicubic bispline surface in the shaded area in FIG. 7 requires 16 surface definition vectors as shown.

Regions Q _{i, j} , Q _{i, j + 1} , Q _{i + 1, j} , Q
_{i + 1, j +} bicubic by spline surface P _i in _{1, j (u,}
w) is expressed as follows using the above-mentioned 16 curved surface definition vectors. P _{i, j} (u, w) = U · M _R · B _R · M _R ^T · W ^T (1) where, in equation (1), U = [u ³ u ² u 1] (0 ≦ u ≦ 1) W = [w ³ w ² w 1] (0 ≦ w ≦ 1) (variables u and w are in the regions Q _{i, j} , Q _{i, j + 1} , Q _{i + 1, j} , Q
Take the above values within _{i, + 1, j + 1} . )

[0103]

(Equation 1)

[0104]

(Equation 2)

In the equation (1), the superscript “T” means transposition.

The bicubic bispline surface generated here generally does not pass through any of the surface definition vectors at the four corners of the region, but continuity when connecting the curved surfaces in adjacent regions is guaranteed. I have.

That is, in step 106, the three-dimensional vector composed of the XY coordinates of the focus sensor S _{i, j} and the measured value Z _{i, j} is used as the curved surface definition vector, and the slit plate is obtained in accordance with the above equation (1). The 90 curved surface shape is calculated.

The shape measuring process is completed by the operations of steps 102 to 106 described above, and the data of the surface shape of the slit plate 90 is stored in the memory 21.

In the next step 108, wafer stage WST is moved to a position where the first measurement pattern on the measurement reticle can be measured by aerial image measurement device 59, and the flow advances to step 110.

In the next step 110, the focus sensor (S _{p, q} ) closest to the slit 22 at that time is determined from the arrangement of the focus sensors S _{i, j} and the measured value of the interferometer at that time. And selects this focus sensor _{Sp, q} .

In the next step 112, the Z correction amount is calculated as follows. That is, X of the selected focus sensor _{Sp, q} , that is, the image forming position of the slit image Sp _{, q} (the incident position of the light flux of the slit image) and the slit 22
The Z correction amount is calculated based on the positional relationship on the Y coordinate system and the bispline surface equation of the corresponding portion.

Here, referring to FIG.
8 and step 110 will be described in further detail.

For example, in step 108, the projection light
Measurement at predetermined points where optical characteristics should be measured in the field of view of the science system PL
At a predetermined point to detect the projected image of the
It is assumed that the lit 22 is arranged, and the slit 22
Focus sensor S_{i, j}, S_{i + 1, j}Figure 8 shows the positional relationship with
In the case shown, the focus sensor S_{i, j}
Is closer to the slit 22, the focus sensor S
_{i, j}Is the focus sensor S _{p, q}Is selected as

In this case, if the Z position is not corrected, the slit plate 90 is set at the position indicated by the solid line during measurement. In this case, only Z
A position error occurs between the original target value and the position error.

Therefore, in step 112, the shape data (bi-spline curved surface type) of the slit plate 22 measured in advance and stored in the memory and the focus sensor S
_The Z position error ΔZ is calculated based on the positions of _{p and q} and the positional relationship between the slit 22 and the XY coordinate system. At the time of measurement to be described later, a value (Ztarg-ΔZ) obtained by subtracting the Z position error ΔZ from the specified Z position Ztarg is used as a new designated Z position.
By adopting the position Ztarg ', as a result, the slit plate 90 is driven from the solid line position in FIG. 8 to the dotted line position (see the arrow C in FIG. 8), and the Z position error of the slit 22 is corrected.

In the next step 114, step 1
Focus sensor S selected in 10 _{p, q}Measurement value (Z_{p, q}
) Is Ztarg ′ (in this case, Ztarg ′ = Ztarg−Δ
The wafer table 18 is moved in the Z-axis direction to a position corresponding to Z).
Go to

In the next step 116, the spatial image of the measurement pattern is formed at the first detection point among the plurality of detection points whose optical characteristics are to be measured in the field of view of the projection optical system PL by the slit scan method described above. measure. During the measurement of the aerial image by slit scanning, the slit plate 9 is monitored while monitoring the measurement results of the selected focus sensors _{Sp, q.}
It is of course possible to always perform tracking and correction of the zero position Z.

In the next step 118, it is determined whether or not the measurement of the aerial image of the measurement pattern within the change range of the Z position scheduled at the first detection point has been completed, and this determination is denied. Then, the process proceeds to step 119 to update the designated Z position to a value larger by one step (Ztarg '← Zta
rg '+ α), the process returns to step 114, and thereafter, while changing the Z position of the wafer table 18 at a predetermined step pitch (α) (step 119), the steps 114, 1
The processes and determinations of steps 16 and 118 are repeated to measure the aerial image at each Z position. Thus, the aerial image measurement data for each Z position is stored in the memory in association with the Z position. The measurement range of the aerial image in the Z-axis direction is determined with, for example, the image plane position of the projection optical system PL immediately before the start of measurement.

When the stepping movement of Z in the expected range is completed, the determination in step 118 is affirmed, and the process proceeds to step 120, where the measurement pattern is detected at all the detection points in the field of view of the projection optical system PL. It is determined whether or not the aerial image measurement has been completed. If this determination is denied, the process returns to step 108, and moves wafer stage WST to a position where the measurement pattern can be measured by aerial image measurement device 59 at the second detection point on the measurement reticle. The following processing and determination are repeated, and the aerial image measurement of the measurement pattern is performed at the second detection point.

When the measurement of the aerial image of the measurement pattern is completed at the second detection point, the flow shifts to step 120, and if this determination is denied, the flow returns to step 108.
Thereafter, the aerial image measurement of the measurement pattern is performed at the third and subsequent detection points in the same manner as described above.

When the aerial image measurement of the measurement pattern has been completed at all the detection points in this way, the determination in step 120 is affirmed, and the process proceeds to step 122. Here, at the time when the aerial image measurement of the measurement pattern is completed at all the detection points, the aerial image measurement data for each Z position is stored in the memory in association with the Z position for each measurement pattern. Therefore, in step 122, for each measurement pattern, a Z position (best focus position) at which the contrast of the intensity signal of the aerial image is maximized is determined, and a predetermined statistical process is performed based on each obtained best focus position. By doing so, the image plane shape of the projection optical system PL is calculated. The image plane of the projection optical system PL, that is, the best imaging plane, is a plane composed of a set of best focus points at countless points at different distances from the optical axis (that is, countless points at different so-called image heights). Therefore, the image plane shape can be easily and accurately obtained by such a method.

In the above description, the case where the image plane shape of the projection optical system PL is calculated has been described. However, if the best focus position of the projection optical system PL is to be detected,
The control algorithm shown in the flowchart of FIG. 6 can be used almost as it is. That is, in this case, since the aerial image measurement is performed only on the measurement pattern positioned on the optical axis of the projection optical system PL,
The determination at 0 is immediately affirmed at the first time, and the process proceeds to step 122. Therefore, in step 122, the Z position at which the contrast of the aerial image intensity signal of the measurement pattern obtained at the only detection point (on the optical axis of the projection optical system PL) becomes maximum may be calculated as the best focus position.

For detecting the spherical aberration of the projection optical system PL, for example, a measurement reticle on which a plurality of L / S patterns having the same line width and different periods are formed is used.
Instead of the step 108, a step of moving the reticle stage RST such that different measurement patterns on the measurement reticle are sequentially positioned on the optical axis of the projection optical system PL, for example, is employed. The Z position (best focus position) where the contrast of the intensity signal of the aerial image is maximized for the pattern for use,
If the spherical aberration is calculated by performing a predetermined calculation based on the difference between the obtained best focus positions for each measurement pattern, the control algorithm shown in the flowchart of FIG. 6 may be slightly changed. The added one can be used.

When the magnification, distortion, coma and the like of the projection optical system PL are detected based on the detection of the image forming position of the pattern image in the XY plane, the Z position of the slit plate 90 is measured during the measurement. Since it is not necessary to change the position, the algorithm omitting the above steps 114 to 118 is adopted. In step 112, when the wafer stage is moved to the projection image measurement position, the multi-point focal position detection system (60
a, selected focus sensor S _p of _60b), by moving the measurement values of _q (Z _p, and _q) is the position to wafer table 18 matching the (Ztarg-ΔZ) in the Z-axis direction, a slit plate Of the slit 22 using the shape data of
The position may be adjusted. In these cases, in step 122, calculations corresponding to the respective measurement purposes may be performed.

When detecting the illumination telecentricity, basically, a control algorithm similar to the above-described spherical aberration measurement can be employed. However, in this case, when calculating the measurement result in step 122, it is necessary to calculate the imaging position at each defocus position, and obtain the illumination telecentricity based on the calculation result.

As described above in detail, according to the exposure apparatus 100 of the first embodiment, when detecting the optical characteristics of the projection optical system PL, the main controller 20 executes the processing before detecting the aerial image. Steps 102-1 described above
By the processing of step 06, the shape data (three-dimensional bi-spline) of the slit plate 90 which is arranged almost perpendicular to the optical axis AX of the projection optical system PL and in which a slit 22 is formed as a detection unit of the aerial image measuring instrument 59 is formed. Surface data) is required.

Next, among the focus sensors which are measurement points of the multi-point focal position detection system (60a, 60b) for measuring the position of the surface of the slit plate 90 in the optical axis direction (Z-axis direction) of the projection optical system PL, The focus sensor _{Sp, q which} is estimated to be closest to the slit 22 at the time of image detection is selected.

In detecting an actual aerial image,
The Z position of the slit plate 90 in the focus sensor Sp _{, q} of the multipoint focal position detection system (60a, 60b) is measured, and the measurement result and the focus sensor S at the time of measurement are measured.
_Using the aerial image measuring instrument 59 with the position of the slit plate 90 in the Z-axis direction corrected based on the positional relationship between _{p, q} and the slit 22 and the shape data previously obtained,
The aerial image measurement of the measurement pattern is performed. Therefore, the aerial image measurement can be performed in a state where the Z position of the slit 22 is accurately set to a desired position without being affected by the surface shape of the slit plate 90. In this case, unlike the related art in which the slit plate 90 (wafer stage WST) is moved in the XY plane to measure the aerial image after setting the Z position of the slit 22 to the desired position, the wafer stage WST The movement surface shape (running surface shape) due to the movement in the XY plane is hardly affected. Therefore, an aerial image of the measurement pattern can be accurately detected.
Then, based on the measurement result of the aerial image, the projection optical system P
Since the optical characteristics of L are calculated, the projection optical system P
The optical characteristics of L can be detected with high accuracy. Therefore, based on the measurement result of the optical characteristics, the optical performance of the projection optical system PL can be adjusted with high accuracy, for example, when the exposure apparatus is started in a factory. Or,
In particular, the above measurement is periodically performed for distortion, magnification, and the like, and the projection optical system P
L (not shown) (for example, the projection optical system P
Distortion and magnification (particularly, a device for adjusting the internal pressure of an airtight chamber provided between specific lenses constituting a projection optical system, or a device for driving a specific lens element constituting L in a Z-tilt manner, or a particular lens constituting a projection optical system). (A non-scanning direction at the time of scanning exposure) can be corrected. The correction of the magnification in the scanning direction during the scanning exposure is performed, for example, by adjusting the scanning speed of at least one of the reticle and the wafer during the scanning exposure.

As described above, in the exposure apparatus 100, the optical characteristics of the projection optical system PL can be adjusted with high precision by, for example, initial adjustment of the optical characteristics of the projection optical system or adjustment of the optical characteristics of the projection optical system prior to the start of exposure. The reticle pattern is transferred onto the wafer W in a state where the relative position between the image of the reticle pattern projected by the projection optical system PL and the wafer is adjusted in consideration of the detected optical characteristics. Will be Therefore, it is possible to perform exposure with good overlay accuracy.

In the above embodiment, the case where the wafer table 18 is step-moved in the Z-axis direction at the time of aerial image measurement has been described. However, the present invention is not limited to this, and involves the operation of scanning the wafer table 18 in the Z-axis direction. Even in the case of performing measurement, the same effect can be obtained by adopting the Z position correction in consideration of the shape of the slit plate 90 described above.

<< Second Embodiment >> Next, a second embodiment of the present invention will be described with reference to FIG. Here, the same reference numerals are used for the same or equivalent components as those of the first embodiment. Book second
The exposure apparatus according to this embodiment has the same configuration as that of the above-described first embodiment, and differs only in a part of the control algorithm for measuring the optical characteristics of the main controller 20. Therefore, in the following, the difference will be mainly described in order to omit redundant description as much as possible.

FIG. 9 is a flowchart showing a control algorithm of the main controller 20 when measuring the image plane shape as an example of the optical characteristics of the projection optical system PL in the exposure apparatus according to the second embodiment. Have been. Hereinafter, the measurement operation of the image plane shape of projection optical system PL by main controller 20 will be described with reference to FIG.

In steps 202 to 206, the operation of the shape measuring step is performed in exactly the same procedure as in steps 102 to 106 described above, and the data of the surface shape of the slit plate 90 is stored in the memory 21.

In the next step 208, the projection optical system PL
The wafer stage WST is moved to a position where the measurement pattern can be measured by the aerial image measurement device 59 at the first detection point in the field of view, and the process proceeds to step 210.

In the next step 210, the focus sensor ( _{Sp, q} ) closest to the slit 22 at that time is determined from the arrangement of the focus sensors S _{i, j} and the measured value of the interferometer at that time. And selects this focus sensor _{Sp, q} .

In the next step 212, the Z position Z at which the measurement value (referred to as Z _{p, q} ) of the focus sensor S _{p, q} is designated
The wafer table 18 is moved in the Z-axis direction to a position corresponding to targ.

In the next step 214, the aerial image of the measurement pattern is measured at the first detection point by the slit scanning method described above. In this case as well, during the measurement of the aerial image by the slit scan, while monitoring the measurement result of the selected focus sensor _{Sp, q} , the Z plate of the slit plate 90 is monitored.
It is, of course, possible to always track and correct the position.

In the next step 216, it is determined whether or not the measurement of the aerial image of the measurement pattern within the change range of the Z position scheduled at the first detection point has been completed, and this determination is denied. And the process proceeds to step 217 to update the designated Z position to a value larger by one step (Ztarg ← Ztarg
+ Α), the process returns to step 212, and thereafter, while changing the Z position of the wafer table 18 at a predetermined step pitch (α) (step 217), steps 212 and 21 are performed.
The processes and determinations of 4,216 are repeated, and aerial image measurement is performed for each Z position. Thus, the aerial image measurement data for each Z position is stored in the memory 21 in association with the Z position.

When the Z step movement in the expected range is completed, the determination in step 216 is affirmed, and the flow advances to step 218 to set the XY position of wafer stage WST to the start position of the slit scan. The positional relationship between the focus sensor _{Sp, q} selected earlier, that is, the image forming position of the slit image Sp _{, q} (the incident position of the light flux of the slit image) and the slit 22 on the XY coordinate system, The Z correction amount is calculated based on the spline surface equation, and is correlated with the first measurement pattern.
To memorize.

In the next step 220, it is determined whether or not the aerial image measurement of the measurement pattern has been completed at all the detection points. If this determination is denied, the process returns to step 208,
At the second detection point, the measurement pattern is
After that, the wafer stage WST is moved so as to be measured, and thereafter, the processing and determination of step 210 and subsequent steps are repeated, and the aerial image measurement of the measurement pattern is performed at the second detection point.

When the measurement of the aerial image of the measurement pattern is completed at the second detection point, the flow shifts to step 218, where the Z correction value is calculated in the same manner as described above and associated with the second detection point. After storing in the memory 21, step 22
Go to 0. If the determination in step 220 is negative, the process returns to step 208, and the aerial image measurement of the measurement pattern is performed at the third and subsequent detection points in the same manner as described above.

When the aerial image measurement of the measurement pattern has been completed at all the detection points in this way, the determination in step 220 is affirmative, and the process proceeds to step 222. Here, when the aerial image measurement for all the measurement patterns is completed, the aerial image measurement data and the Z correction amount for each Z position are stored in the memory 21 for each detection point.
Is stored within. Therefore, in step 222, for each measurement pattern, a Z position (best focus position) at which the contrast of the intensity signal of the aerial image is maximum is determined, and the obtained best focus position is determined using the corresponding Z correction amount. The corrected value is calculated as a true best focus position, and a predetermined statistical process is performed using the calculation result, thereby calculating the image plane shape of the projection optical system PL.

Also in the second embodiment, the flowchart of FIG. 9 is directly or partially modified, so that not only the calculation of the image plane shape of the projection optical system PL but also the best focus position, spherical aberration, magnification, distortion,
Optical characteristics such as coma aberration can be measured. Also in this case, it is possible to measure the illumination telecentricity.

As described above in detail, according to the exposure apparatus of the second embodiment, when detecting the optical characteristics of the projection optical system PL, prior to the detection of the aerial image, the steps 202 to 206 described above are performed. By the processing, the aerial image measuring device 59 is disposed substantially perpendicular to the optical axis AX of the projection optical system PL and partially disposed.
The shape data (three-dimensional bi-spline curved surface data) of the slit plate 90 in which the slit 22 as the detecting unit is formed is obtained.

Next, among the focus sensors which are the measurement points for measuring the position, the focus sensor _{Sp, q which} is assumed to be closest to the slit 22 when the aerial image is detected is selected.

In detecting an actual aerial image,
The Z position of the slit plate 90 in the focus sensor Sp _{, q} of the multi-point focal position detection system (60a, 60b) is measured, and the Z image of the slit plate 90 is set based on the measurement result. Using the measuring device 59, the aerial image measurement of the measurement pattern is performed.

The optical information detected based on the aerial image measurement result based on the positional relationship between the focus sensor S _{p, q} and the slit 22 at the time of aerial image measurement and the shape data previously obtained is included. The Z position information (best focus position in the embodiment) is corrected, and the optical characteristics such as the curvature of field of the projection optical system PL are calculated based on the corrected information.

As described above, in the second embodiment, the Z position information included in the detected optical information is appropriately corrected, and the optical characteristics of the projection optical system are calculated based on the corrected information. Therefore, the optical characteristics of the projection optical system can be detected with high accuracy. In this case as well, there is almost no influence on the surface shape of slit plate 90, and there is almost no influence on the moving surface shape (running surface shape) due to the movement of wafer stage WST in the XY plane.

Therefore, in the exposure apparatus according to the second embodiment, similarly to the above-described first embodiment, for example, the initial adjustment of the optical characteristics of the projection optical system, or the projection optical system prior to the start of exposure. Adjustment of the optical characteristics of the projection optical system P
The reticle pattern wafer is adjusted in a state where the relative position between the image of the reticle pattern projected by the projection optical system PL and the wafer is adjusted by adjusting the optical characteristics of L with high precision or taking the detected optical characteristics into consideration. Transfer onto W is performed. Therefore, it is possible to perform exposure with good overlay accuracy.

In the second embodiment, the case where the wafer table 18 is step-moved in the Z-axis direction when measuring the aerial image has been described. However, the present invention is not limited to this, and the wafer table 18 is scanned in the Z-axis direction. Even in the case of performing measurement involving an operation, the same effect can be obtained by adopting the Z position correction in the optical information detected in consideration of the shape of the slit plate 90 described above.

However, the method for measuring the optical characteristics of the projection optical system according to the second embodiment requires measurement at a specific Z position such as a best focus position or a fixed defocus position from the best focus position. It is unsuitable in cases such as This is because the slit 22 is not actually set at the specific Z position during measurement. In such measurement, the method for measuring the optical characteristics of the projection optical system according to the first embodiment described above is effective.

In each of the above embodiments, the case where the shape of the slit plate 90 is measured each time the aerial image is measured is described, but the present invention is not limited to this. That is, the shape measurement of the slit plate 90 may be performed only at the time of manufacture, adjustment, or the like, and measurement data obtained when the shape measurement of the slit plate 90 is performed may be stored in the memory 21. In such a case, at the time of measuring the aerial image, main controller 20 executes step 1 in FIG.
Only the control operation after step 08 or step 208 in FIG. 9 needs to be performed.

In each of the above embodiments, the slit plate 9
In calculating the shape of 0, a bicubic bi-spline surface equation was used, but the present invention is not limited to this, and any general bi-spline complement can be applied. Further, when the surface accuracy of the plate-shaped member is originally high, plane complementation using measurement data of several adjacent points can be adopted. In addition,
The surface of the plate-shaped member may be divided into matrix-shaped partitioned areas of a required size in advance, and Z position data for each partitioned area may be provided in the form of a map.

Further, in each of the above embodiments, the case where the multi-point focal position detecting system (60a, 60b) is used as the measuring device has been described. However, the present invention is not limited to this, and the laser interferometer (for example, Fizeau An interferometer) or another surface position measuring device may be used. In short, it is only necessary that the surface position information of at least three points of the plate member can be measured simultaneously.

In each of the above embodiments, the case where the specific component provided on the plate-like member is the slit 22 has been described. However, it is needless to say that the present invention is not limited to this. The specific component is a component of the detection system (the aerial image measuring device 59 in the above embodiment), and is provided on the substrate stage, and changes in the position of the optical axis in the optical axis direction change the optical information to be detected. Components are sufficient. Such components include, for example, light receiving units (for example, photoelectric conversion elements) and light emitting units of various optical sensors.

Therefore, the detection system is not limited to the aerial image measurement device,
It broadly includes a detection system that is at least temporarily mounted on a wafer table of an exposure apparatus such as a wavefront aberration measurement apparatus and an uneven illuminance sensor or on a movable body different from the wafer table. The wavefront aberration measuring device detects a measurement pattern through a minute opening (such as a pinhole) with, for example, a line sensor or an image sensor, and detects a lateral displacement of the spatial image from a reference position, thereby projecting a projection optical system. Calculate the wavefront aberration of the system.

In addition, the detection system includes a reference mark (for example, a line and space having a fixed pitch) fixed on the wafer table of the exposure apparatus or another movable body at a position substantially at the same height as the surface of the wafer W. Pattern consisting of 0
The four types of diffraction grating marks (amplitude or phase type) formed with the periodic directions of 45 °, 45 °, 90 °, and 135 ° are formed from the inside of the wafer table at or near the exposure wavelength. Illuminated by the illumination light of the wavelength, the image light flux generated from the reference mark is applied to the pattern surface of the reticle via the projection optical system, and the light flux of the reflected image reflected on the pattern surface is projected onto the reference pattern via the projection optical system. A detection system for focus calibration, in which the light flux of the reflected image is received by an optical sensor arranged at a position almost conjugate with the pupil plane of the projection optical system via the reference pattern. According to this detection system, the reference mark is moved in the direction of the optical axis so as to cross the best imaging plane of the projection optical system, so that the photoelectric conversion signal from the optical sensor and the wafer table (the position of the reference mark in the direction of the optical axis) can be obtained. , The best imaging position (best focus position) can be accurately detected. Further, in this detection system, the best focus position can be obtained at an arbitrary position in the field of view of the projection optical system, similarly to the aerial image measuring device described above.

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 is used as the projection optical system has been described. However, the present invention is not limited to this, and an equal magnification or enlargement system may be used as the projection optical system. Any of a refraction system and a reflection system may be used.

An illumination optical system comprising a plurality of lenses;
The projection optical system is incorporated into the exposure apparatus main body to perform optical adjustment, and a reticle stage and wafer stage consisting of many mechanical parts are attached to the exposure apparatus main body to connect wiring and piping, and are further adjusted (electrical adjustment, operation confirmation, etc.) 2), the exposure apparatus of the present embodiment can be manufactured. 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.

In the semiconductor device, a step of designing the function and performance of the device, a step of manufacturing a reticle based on the design step, a step of manufacturing a wafer from a silicon material, and a step of forming a reticle pattern by the exposure apparatus of the above-described embodiment. It is manufactured through a step of transferring to a wafer, a step of assembling a device (including a dicing step, a bonding step, and a package step), an inspection step, and the like.

[0164]

As described above, according to the exposure apparatus of the present invention, the shape of the moving surface of the substrate stage and the surface shape of the plate-like member on which specific components constituting the detection system are arranged are different. In addition, there is an effect that the influence on the measurement result can be reduced at the same time, and highly accurate optical measurement and, consequently, highly accurate exposure can be performed.

According to the optical characteristic detecting method of the present invention,
There is an effect that the optical characteristics of the projection optical system can be detected with high accuracy.

According to the exposure method of the present invention, there is an effect that highly accurate exposure can be performed.

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing the wafer stage WST of FIG. 1 taken out therefrom.

FIG. 3 is a diagram showing a state in which a spatial image of a measurement pattern formed on a reticle is being measured by using the aerial image measuring device, and is a front view showing a part of a wafer table in a crushed state. FIG.

FIG. 4 is a view showing a portion 4 formed near an exposure area IA on the wafer surface.
It is a top view showing arrangement of nine slit images.

FIGS. 5A to 5C are diagrams for explaining a method of measuring an aerial image by the aerial image measuring device.

FIG. 6 is a flowchart illustrating a control algorithm of a main controller when measuring an image plane shape of an optical characteristic of a projection optical system in the first embodiment.

FIG. 7 is a diagram for describing a method of calculating a bicubic bispline surface.

FIG. 8 shows a slit 22 and a focus sensor S _{i, j,} S
It is a figure which shows notionally the relationship between _{i + 1, j} and Z position error (DELTA) Z.

FIG. 9 is a flowchart illustrating a control algorithm of a main controller when measuring an image plane shape of an optical characteristic of a projection optical system in the second embodiment.

[Explanation of symbols]

18 wafer table (substrate stage), 20 main controller (control device), 21 memory (storage device), 22
Slit (specific component, detection unit), 59: spatial image measuring device (projection image detection system, detection system), 60a: light transmission system (part of measurement device), 60b: light receiving system (part of measurement device) , 90
... Slit plate (plate-like member), 100 ... Exposure device, R ... Reticle (mask), PL ... Projection optical system, W ... Wafer (substrate).

Claims (13)

[Claims] 1. An exposure apparatus for transferring a pattern of a mask onto a substrate via a projection optical system, comprising: a substrate stage for holding the substrate; and a substrate stage substantially perpendicular to an optical axis of the projection optical system. A detection system that includes at least a specific component disposed on a part of the plate-shaped member installed in the projection optical system, and detects optical information that changes according to the position of the specific component in the optical axis direction of the projection optical system; A measurement device that has a fixed positional relationship with the projection optical system and is capable of measuring position information of the surface of the plate member in the optical axis direction; and at least the surface of the plate member measured in advance using the measurement device. A storage device in which shape data of the surface of the plate-like member obtained based on the position information of the three points in the optical axis direction is stored. 2. The exposure apparatus according to claim 1, wherein the measuring device is an obliquely incident light type multi-point focal position detecting device. 3. The storage device stores bi-spline curved surface data calculated based on positional information in the optical axis direction of the surface of the plate member measured in advance using the measurement device. 2. The exposure apparatus according to claim 1, wherein the data is stored as shape data. 4. A method for detecting the optical information at a predetermined point in the field of view of the projection optical system using the detection system, and a position of a measurement point of the measurement device and the specific component constituting the detection system. A control device that corrects a position in the optical axis direction of the plate member set using the measurement device at the time of the detection, based on the shape data stored in the storage device, according to the relationship. The exposure apparatus according to claim 1, wherein: 5. A method for detecting the optical information at a predetermined point in the field of view of the projection optical system using the detection system, and the position of a measurement point of the measurement device and the specific component constituting the detection system. A control device that corrects the detection result or position information at the predetermined point in the optical axis direction obtained from the detection result based on the shape data stored in the storage device, according to the relationship. The exposure apparatus according to claim 1, wherein: 6. detecting the optical information at a predetermined point different from a measurement point of the measurement device in a field of view of the projection optical system using the detection system, and detecting the shape data stored in the storage device; The apparatus according to any one of claims 1 to 3, further comprising a control device that determines calibration information of the measurement device on the measurement point based on position information on the optical axis direction obtained from the detection result. Exposure apparatus according to Item. 7. The exposure apparatus according to claim 1, wherein the detection system is a projection image detection system that detects a projection image projected by the projection optical system. 8. An optical characteristic detecting method for detecting an optical characteristic of a projection optical system that projects a pattern arranged on a first surface onto a second surface, wherein the method is substantially perpendicular to an optical axis of the projection optical system. A first step of obtaining shape data of the surface of the plate-like member provided with a detection unit of a detection system for detecting optical information in a part thereof; and measuring the position information of the surface of the plate-like member in the optical axis direction. The position information on the optical axis direction of the surface of the plate member at a specific measurement point of the device is measured, and the measurement result and the positional relationship between the specific measurement point and the detection unit at the time of measurement, and the obtained Based on the shape data, in a state where the position in the optical axis direction of the plate-like member set using the measuring device is corrected, the position of the detection unit in the optical axis direction is detected using the detection system. Changes according to Third for calculating the optical characteristic of the projection optical system based on a detection result of the optical information; second step and detecting an academic information
And a method for detecting optical characteristics. 9. An optical characteristic detecting method for detecting an optical characteristic of a projection optical system for projecting a pattern arranged on a first surface onto a second surface, wherein the method is substantially perpendicular to an optical axis of the projection optical system. A first step of obtaining shape data of the surface of the plate-like member provided with a detection unit of a detection system for detecting optical information in a part thereof; and measuring the position information of the surface of the plate-like member in the optical axis direction. Using a device, measure the position information of the surface of the plate member in the optical axis direction, and set the position of the plate member in the optical axis direction based on the measurement result, using the detection system. A second step of detecting optical information that changes in accordance with the position of the detection unit with respect to the optical axis direction; a positional relationship between a specific measurement point of the measurement device and the detection unit at the time of the detection; Based on the shape data The detected optical information, or the third step and determining the optical characteristics of the projection optical system by correcting the position information of the optical axis direction included in the optical information Te; optical characteristic detecting method comprising. 10. The optical information is detected while setting the detection unit at a predetermined point in the field of view of the projection optical system and changing the position of the plate-like member in the optical axis direction using the measurement device. 10. The optical characteristic detecting method according to claim 8, wherein the optical characteristic of the projection optical system at the predetermined point is calculated. 11. The measurement device can measure position information of the plate-like member in the optical axis direction at each of a plurality of measurement points, and the specific measurement point is detected by the detection unit when detecting the optical information. The optical characteristic detecting method according to claim 8, wherein the measurement point is a measurement point located at a position closest to the measurement point. 12. In the first step, the plate-like member is
Moved directly below the projection optical system, measuring the position information in the optical axis direction of the projection optical system at at least three points on the surface of the plate member moved directly below the projection optical system using the measurement device, The optical characteristic detecting method according to any one of claims 8 to 11, further comprising calculating shape data of the surface of the plate member based on the measurement result. 13. An exposure method for transferring a pattern of a mask onto a substrate via a projection optical system, wherein the method for detecting an optical characteristic according to claim 8 is used prior to exposure. Detecting the optical characteristics of the projection optical system by adjusting the relative position between the image of the mask pattern projected by the projection optical system and the substrate in consideration of the detected optical characteristics. Performing the transfer of the mask pattern.