JP2001313250A - Aligner, its adjusting method, and method for fabricating device using aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aligner in which an illumination optical system can be adjusted accurately in a short time. SOLUTION: A reticle R is irradiated with an exposing light IL from an exposing light source 1 through an illumination optical system ILS comprising a first fly eye lens 6, a second fly eye lens 9, lens systems 12, 13 blinds 14A, 14B, and condenser lens systems 17, 18 and the pattern image of the reticle R is projected onto a wafer W through a projection optical system PL. Specific illumination characteristics are measured using an evaluation mark plate 33 on a reticle stage 31, and a spatial image measuring system 46 provided on a wafer state 39 and then the state of the second fly eye lens 9 and the lens systems 12, 13 is adjusted through drive units 23, 24 and 25 based on the measurements.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of transferring a mask pattern onto a substrate through a projection optical system in a lithography process for manufacturing, for example, a semiconductor device, a liquid crystal display device, a plasma display device, or a thin film magnetic head. Exposure apparatus used for this, and an exposure apparatus adjustment method, and particularly to an exposure apparatus having a function of automatically adjusting an illumination system.

[0002]

2. Description of the Related Art A lithography process (typically, a resist coating process, an exposure process, and a resist development process) for manufacturing a semiconductor device is performed in order to cope with an improvement in the degree of integration and fineness of a semiconductor device. In an exposure apparatus, it is required to further improve resolution, transfer fidelity, and the like. As described above, in order to increase the resolution and the transfer fidelity, the wavelength of the exposure light as the exposure beam was shortened, and a projection optical system having a large numerical aperture was used. It is necessary to perform exposure amount control for exposing a photoresist at an appropriate exposure amount with high accuracy. In order to bring out the imaging characteristics of the projection optical system to the limit and to control the exposure amount of the photoresist with high accuracy, the illumination characteristics of the illumination optical system that illuminates the reticle as a mask with the exposure light are enhanced as much as possible. Thus, it is necessary to optimize the illumination optical system.

Conventionally, adjustment for optimizing the illumination optical system of an exposure apparatus has been performed in the following steps. (A) The operator measures the illumination characteristic (for example, uneven illuminance) of the illumination optical system to be adjusted. (B) Based on the measurement result, the state (position, tilt angle, etc.) of a predetermined optical member is adjusted using a drive unit corresponding to the illumination characteristic. The drive amount at this time is set so as to improve the illumination characteristics as much as possible by modifying the optical design values based on the experience of the operator.

(C) After the adjustment, the remaining amount of the illumination characteristic is measured again, and when the remaining amount exceeds the allowable range, readjustment is performed via the drive unit. (D) After the adjustment is completed, the final state (optimal state) of the optical member is stored. Then, in each of the plurality of illumination conditions, the above-described adjustment process is repeated for each illumination characteristic to be adjusted, the optimal state of the corresponding optical member is stored, and when the illumination condition is switched, the corresponding optical Each member was set to an optimal state.

[0005]

As described above, adjustment for optimizing the illumination optical system of the conventional exposure apparatus has been performed by an operator at the time of assembling adjustment of the exposure apparatus and at the time of maintenance. However, when the operator performs the adjustment, there is a disadvantage that the adjustment requires a long time. Furthermore, since it is necessary to adjust the illumination optical system for all of the plurality of illumination conditions, the overall adjustment time has been considerably long. Further, since the time required for the optimization depends on the skill of the operator, the adjustment time may be further increased depending on the operator.

Further, when it is necessary to adjust the state of a plurality of optical members in the illumination optical system, it is necessary to consider mutual influences caused by the adjustment, so that the adjustment process is extremely complicated. . As described above, since the conventional adjustment of the illumination optical system required a long and complicated process, it was possible to perform an operation of changing the allowable level of the predetermined illumination characteristic according to, for example, the required accuracy of the device to be manufactured. It was difficult. Also, for example, the illuminance unevenness in the illumination characteristics may change with time due to fogging of the optical member in the illumination optical system, deterioration of the glass material, and the like. It was difficult to respond.

SUMMARY OF THE INVENTION In view of the foregoing, it is a first object of the present invention to provide an exposure apparatus that can accurately adjust an illumination optical system in a short time. Further, it is a second object of the present invention to provide an exposure apparatus capable of substantially automatically adjusting an illumination optical system capable of switching to a plurality of illumination conditions.

Another object of the present invention is to provide a method for efficiently using such an exposure apparatus and a highly accurate device manufacturing method using the exposure apparatus.

[0009]

A first exposure apparatus according to the present invention includes an illumination system (ILS) for illuminating a first object (R) with an exposure beam, and the illumination beam passes through the first object via the first object. In an exposure apparatus for exposing a second object (W), an illumination condition switching system (10, 10e) arranged in the illumination system for switching the illumination condition of the exposure beam to one of a plurality of illumination conditions, and In order to control a predetermined lighting characteristic of the lighting system according to each of the plurality of lighting conditions,
An adjustment system (23, 24, 25) for adjusting the state of predetermined optical members (9, 12, 13) in the illumination system is provided.

According to the present invention, when the illumination condition is switched by the illumination condition switching system, the state of the optical member (in the optical axis direction) is adjusted via the adjustment system according to the switched illumination condition. Position, position in the direction perpendicular to the optical axis, and tilt angle). Thus, the predetermined illumination characteristics of the illumination system can be controlled to a desired state substantially automatically under a plurality of illumination conditions.

In this case, an example of the predetermined illumination characteristic to be evaluated is at least one of the illuminance unevenness of the exposure beam and the loss of the telecentricity of the exposure beam. These are both very important properties for obtaining high resolution on the second object. Further, the illumination characteristics to be evaluated may be a slope component and a concavo-convex component of uneven illuminance of the exposure beam, a slope component (two-dimensional vector amount) and a magnification component of a telecentricity collapse amount of the exposure beam. desirable. The components of the five illumination characteristics can be easily and almost independently controlled by driving a plurality of optical members in the illumination system independently of each other, so that automation can be particularly easily performed.

Here, the amount of collapse of the telecentricity of the exposure beam is the telecentricity of the illumination system (or the illumination optical system). In addition, a characteristic measurement system (33, 46, 42) for measuring the illumination characteristic of the illumination system, and a driving amount of the adjustment system and a change amount of the illumination characteristic based on a measurement result of the characteristic measurement system. It is desirable to have an arithmetic control system (22) for obtaining and storing the relationship. When the lighting characteristics change over time, for example, the lighting characteristics are periodically measured by the characteristic measurement system, the previously stored relationship is updated by calculation (simulation), or both are used together. (That is, the relationship is updated by calculation during the periodic measurement of the lighting characteristics), and by driving the adjustment system based on this, the lighting characteristics can be quickly returned to the desired state. it can.

Next, the second exposure apparatus of the present invention includes an illumination system (ILS) for illuminating the first object (R) with an exposure beam, and the second object is transmitted through the first object by the exposure beam. In an exposure apparatus for exposing (W), a characteristic measurement system (33, 46, 42) for measuring a predetermined illumination characteristic of the illumination system.
And an adjusting system (23, 24, 24) for adjusting the state of a predetermined optical member in the illumination system according to the measurement result of the characteristic measuring system.
25).

According to the present invention, the adjustment of the illumination system can be accurately performed in a short time by driving the adjustment system based on the measurement result of the characteristic measurement system including the aerial image measurement system. It can be carried out. In these inventions, the illumination system comprises an optical integrator (9) (uniformizer or homogenizer), and the exposure beam passing through the optical integrator is conjugated to the illuminated surface of the first object or the illuminated surface. When the optical system has the first optical system (12) and the second optical system (13) for guiding to the various surfaces, the following illumination characteristics can be substantially adjusted by adjusting the states of these optical members as follows. Can be controlled independently of each other.

(A1) Position adjustment in the optical axis direction of the optical integrator (9): magnification component of the amount of collapse of the telecentricity of the exposure beam, (b1) Position adjustment in the optical axis direction of the first optical system: uneven illuminance Unevenness component, (c1) second
Two-dimensional position adjustment in the direction perpendicular to the optical axis of the optical system: a tilt component (two-dimensional vector amount) of the amount of collapse of the telecentricity of the exposure beam, (d1) the tilt angle of the second optical system: the unevenness of illuminance The tilt component in the tilt direction. In the case of a scanning exposure type exposure apparatus, the tilting direction preferably corresponds to a non-scanning direction orthogonal to the scanning direction. This is because illuminance non-uniformity is averaged in the scanning direction by the integration effect, but is not corrected in the non-scanning direction.

Further, in the present invention, the illumination system sets the illuminance distribution of the exposure beam to a local area for deformed illumination by the illumination system and the exposure beam from the exposure light source. A beam shaping optical system (5) for guiding the optical element, a condensing optical system (7A, 7B) for guiding an exposure beam from the optical element (55), and a uniform illuminance distribution of the exposure beam from the condensing optical system. When an optical integrator (9) (uniformizer or homogenizer) is provided, it is desirable that the adjustment system adjusts the state of the condensing optical system or the beam shaping optical system.

At this time, for example, by adjusting the beam shaping optical system so as to balance the magnitude of the illuminance of the exposure beam and the magnitude of the variation in the illuminance distribution of the exposure beam, the loss of the exposure beam is reduced. , And uneven illuminance can be reduced. Further, the third exposure apparatus of the present invention includes an illumination system (ILS) for illuminating the first object (R) with the exposure beam, and the second object (W) is irradiated with the exposure beam via the first object. In an exposure apparatus that performs exposure, the amount of collapse of the telecentricity of the exposure beam in the illumination system is measured separately for a tilt component and a magnification component. By dividing the component into the tilt component and the magnification component in this manner, the adjustment can be easily performed almost independently of each other.

The exposure apparatus of the present invention has a first movable body (31) on which the first object is mounted, and a second movable body (39) on which the second object is mounted. , The first
And a drive system (34, 41) for synchronously driving the second movable body, and the second object may be scanned and exposed by the exposure beam via the first object. in this case,
The exposure beam is detected on a predetermined surface on which the second object is disposed, and a non-scanning direction orthogonal to the scanning direction in which the first and second objects are moved during the scanning exposure in the irradiation area of the exposure beam. It is desirable to measure a tilt component of the illuminance unevenness in the direction. When performing the scanning exposure, the illuminance unevenness in the scanning direction is reduced by the averaging effect. Therefore, the measuring device can be simplified by measuring the illuminance unevenness in the non-scanning direction.

Further, an exposure beam applied to a mark (36A) provided on the first movable body other than the first object may be detected to measure the amount of collapse. As a result, the illumination characteristics can be measured as necessary without depending on the pattern of the first object (such as a mask). Next, according to the first method of adjusting the exposure apparatus of the present invention, the first object (R) is irradiated with an exposure beam passing through the illumination system (ILS), and the second object is irradiated with the exposure beam via the first object. In the method for adjusting an exposure apparatus for exposing (W), the exposure beam is detected on a predetermined surface on which the second object is arranged, and the telecentricity of the illumination system and the exposure beam within the irradiation area of the exposure beam are detected. And measuring the illumination characteristics including at least one of the illuminance and the light amount distribution, and based on the measured illumination characteristics, the optical member (9, 1) in the illumination system.
2 and 13), and until the illumination characteristic is measured next, the measured illumination characteristic is updated by calculation, and the optical member is driven based on the updated illumination characteristic. is there.

According to the present invention, the illumination characteristic of the illumination system can be adjusted in a short time and with high accuracy by reducing the frequency of measurement of the illumination characteristic. In this case, the first movable body (31) on which the first object is mounted and the second movable body (39) on which the second object is mounted are driven synchronously to allow the first object to move through the first object. Then, the second object may be scanned and exposed with the exposure beam, and its illumination characteristics may be measured using a mark (36A) provided on the first movable body other than the first object.

Further, the exposure beam is detected on a predetermined surface on which the second object is arranged, and a scanning direction in which the first and second objects are moved during the scanning exposure in an irradiation area of the exposure beam. The inclination component of the illuminance unevenness in the non-scanning direction orthogonal to the above may be measured. In the case of the scanning exposure method, illuminance unevenness in the scanning direction is reduced by the averaging effect, so measuring the components in the non-scanning direction simplifies the measurement process and efficiently measures the required illumination characteristics. it can.

Next, a second method for adjusting an exposure apparatus according to the present invention is directed to an illumination system (ILS) for illuminating a first object with an exposure beam.
A method for adjusting an exposure apparatus for exposing a second object with the exposure beam through the first object, wherein the state of the predetermined optical member (9, 12, 13) in the illumination system is changed to a plurality of states. Then, a predetermined illumination characteristic of the illumination system is measured, and a relationship (ratio, etc.) between the driving amount of the optical member and the variation amount of the illumination characteristic is obtained and stored based on the measurement result. Based on the stored relationship, the optical member is driven to control the illumination characteristics. According to the present invention, the illumination characteristics can be efficiently adjusted by previously obtaining the relationship between the drive amount of the optical member and the change amount of the illumination characteristics.

Further, the device manufacturing method of the present invention includes a step of transferring a device pattern (R) onto a workpiece (W) using the exposure apparatus of the present invention. According to the present invention, highly integrated devices can be mass-produced with high accuracy.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a scanning exposure type projection exposure apparatus of a step-and-scan method or a step-and-stitch method. FIG. 1 shows a schematic configuration of a projection exposure apparatus of this embodiment. In FIG. 1, an ArF excimer laser light source (wavelength 193 nm) is used as an exposure light source 1.
However, as the exposure light source 1, KrF excimer laser (wavelength 248 nm), F ₂ laser (wavelength 157 nm), Kr
_{A two-} laser (wavelength: 146 nm), a harmonic generator of a YAG laser, a harmonic generator of a semiconductor laser, a mercury lamp, or the like can be used. Wavelength 1 from exposure light source 1
Exposure light IL (exposure beam) composed of 93 nm ultraviolet pulse light is a beam matching unit (BMU) 2 for positionally matching an optical path with an exposure apparatus main body.
And enters the variable attenuator 3 as an optical attenuator. An exposure control unit 21 for controlling the amount of exposure to the photoresist on the wafer controls the start and stop of light emission of the exposure light source 1 and the output (oscillation frequency, pulse energy), and the light reduction in the variable dimmer 3. The luminous efficiency is adjusted stepwise or continuously.

The exposure light IL that has passed through the variable dimmer 3 passes through a beam shaping system 5 composed of a first lens system 4A and a second lens system 4B arranged along a predetermined optical axis, and a first-stage optical system. The light enters the first fly-eye lens 6 as an integrator (uniformizer or homogenizer). The exposure light IL emitted from the first fly-eye lens 6 passes through a first lens system 7A, a mirror 8 for bending the optical path, and a second lens system 7B as a second stage optical integrator. The light enters the eye lens 9. The first lens system 7A and the second lens system 7B constitute a relay optical system (or a beam shaping system) as a condensing optical system.

An aperture stop plate 10 is provided on the exit surface of the second fly-eye lens 9, that is, an optical Fourier transform surface (pupil surface of the illumination system) with respect to the pattern surface (reticle surface) of the reticle R to be exposed. 10e rotatably arranged. As shown in a front view in FIG. 6B, the aperture stop plate 10 has a circular aperture stop 10a for normal illumination, an aperture stop 10b for annular illumination as an example of modified illumination, and another modified illumination for modified illumination. The aperture stop 10c composed of a plurality of (four in this example) eccentric small apertures for the deformed light source (or so-called oblique illumination) and the small circular aperture stop 10d for the small coherence factor (σ value) are switched. It is arranged freely. The aperture stop 10c can also be called an aperture stop for quadrupole illumination. The illumination conditions are changed from the aperture stop plate 10 and the drive motor 10e to a plurality of illumination conditions (normal illumination,
A “lighting condition switching system” for switching to any of the modified lighting and the small σ value lighting is configured, and a main control system 22 that supervises and controls the operation of the entire apparatus sets lighting conditions via a drive motor 10e. .

In FIG. 1, an aperture stop 10a for normal illumination is provided on the exit surface of the second fly-eye lens 9, and the aperture stop 10a is emitted from the second fly-eye lens 9 to emit light.
The exposure light IL that has passed through 0a is incident on the beam splitter 11 having a high transmittance and a low reflectance. The exposure light reflected by the beam splitter 11 is incident on an integrator sensor 20 composed of a photoelectric detector via a converging lens 19, and a detection signal S 1 of the integrator sensor 20 is supplied to an exposure control unit 21. The relationship between the detection signal of the integrator sensor 20 and the illuminance of the exposure light IL on the wafer W as a substrate to be exposed is measured in advance with high accuracy.
It is stored in a memory in the exposure control unit 21. The exposure control unit 21 is configured to monitor the illuminance (average value) of the exposure light IL on the wafer W indirectly from the detection signal of the integrator sensor 20 and the integrated value thereof.

Exposure light I transmitted through beam splitter 11
L sequentially passes through the first lens system 12 (first optical system) and the second lens system 13 (second optical system) along the optical axis IAX,
The light enters the fixed blind (fixed illumination field stop) 14A and the movable blind (movable illumination field stop) 14B. The latter movable blind 14B is disposed on a conjugate plane with respect to the reticle plane, and the former fixed blind 14A is disposed on a plane defocused by a predetermined amount from the conjugate plane. The fixed blind 14A is disclosed in, for example, JP-A-4-196513.
As disclosed in Japanese Patent Application Laid-Open Publication No. H11-260, non-scanning that is substantially centered on the optical axis AX within the circular visual field of the projection optical system PL and is orthogonal to the scanning direction (Y direction) in which the reticle R and the wafer W are moved during scanning exposure. It has an opening arranged so as to extend in a linear slit shape or a rectangular shape (hereinafter, collectively referred to as “slit shape”) in the direction (X direction). That is, in this example, the fixed blind 14A includes an illumination area 35 on the reticle R to which the exposure light IL is irradiated, and an exposure area 35P on the wafer W.
The projection optical system PL defines a projection area in which a pattern image in the illumination area 35 is formed in a conjugate with the illumination area 35, and has at least a fixed width in the scanning direction.

Further, the movable blind 14 B
To prevent unnecessary exposure at the start and end of scanning exposure on each of the above shot areas, the illumination area 35 defined by the fixed blind 14A and the width of the exposure area 35P in the scanning direction are made variable. used. The movable blind 14B is also used for making the width thereof variable in the direction (non-scanning direction) orthogonal to the scanning direction SD according to the size of the pattern area of the reticle R. The information on the aperture ratio of the movable blind 14B is stored in the exposure control unit 2
1, the value obtained by multiplying the illuminance obtained from the detection signal of the integrator sensor 20 by the aperture ratio is the actual illuminance on the wafer W. The fixed blind 14A
The arrangement of the movable blind 14B is not limited to that shown in FIG. 1. For example, the fixed blind 14A may be arranged close to the reticle R between the reticle R and the illumination optical system.

The exposure light IL that has passed through the fixed blind 14A during exposure passes through a mirror 15 for bending the optical path, a lens system 16 for imaging, a sub-condenser lens system 17, and a main condenser lens system 18 to serve as a mask. Illumination area (illumination visual field area) 3 on the pattern surface (lower surface) of reticle R
Light 5 Under the exposure light IL, an image of the circuit pattern in the illumination area of the reticle R is projected at a predetermined projection magnification β (β is, for example, 1 through a bi-telecentric projection optical system PL.
/ 4, 1/5, etc.), the image is transferred to a slit-shaped exposure area 35P of a photoresist layer on a wafer W as a substrate (substrate to be exposed) disposed on the image plane of the projection optical system PL.
The reticle R and the wafer W correspond to the first object and the second object, respectively, of the present invention, and the wafer (wafer) W is, for example, a semiconductor (such as silicon) or SOI (silicon on insulator).
This is a disk-shaped substrate such as r). The projection optical system PL as the projection system in this example is a diopter system (refraction system).
It goes without saying that a catadioptric system (catadioptric system) or a reflective system can also be used. Hereinafter, the Z axis is taken in parallel with the optical axis AX of the projection optical system PL, the Y axis is taken in the scanning direction (here, the direction parallel to the plane of FIG. 1) in a plane perpendicular to the Z axis, and orthogonal to the scanning direction. The description will be made by taking the X axis in the non-scanning direction (in this case, the direction perpendicular to the paper surface of FIG. 1).

In FIG. 1, an exposure light source 1, a beam matching unit 2, a variable dimmer 3, a beam shaping system 5, a first
Fly-eye lens 6, first lens system 7A, second lens system 7B, second fly-eye lens 9, first lens system 12, second lens system 13, fixed blind 14A, movable blind 14B, imaging lens system 16, Sub condenser lens system 1
7 and the illumination optical system I from the main condenser lens system 18 and the like.
An illumination optical system ILS corresponds to the illumination system of the present invention. Then, the optical axis IAX of the illumination optical system ILS
Coincides with the optical axis AX of the projection optical system PL on the reticle R. In this example, a first drive unit 23, a second drive unit 24, and a drive unit group 25 are mounted on the second fly-eye lens 9, the first lens system 12, and the second lens system 13, respectively.

FIG. 2 is a perspective view showing the relationship between the optical system from the second fly-eye lens 9 to the second lens system 13 in FIG. 1 and the illumination area 35. In FIG. The directions on the second fly-eye lens 9 corresponding to the scanning direction SD (Y direction) and the non-scanning direction (X direction) of the reticle are the y direction and the x direction, respectively.
The first drive unit 23 adjusts the position of the second fly-eye lens 9 in the optical axis IAX direction (the direction of arrow A1), and the second drive unit 24 adjusts the optical axis I of the first lens system 12.
The position in the direction of AX (direction of arrow A2) is adjusted. The drive unit group 25 shown in FIG. 1 includes a third drive unit 25X, a fourth drive unit 25Y, and a fifth drive unit 25T shown in FIG.
And 25Y are the x direction (direction of arrow A3) and the y direction (arrow A4) perpendicular to the optical axis IAX of the second lens system 13, respectively.
Direction) is adjusted, and the drive unit 25T
The tilt angle around an axis passing through the optical axis IAX of the lens system 13 and parallel to the y-axis (in the direction of arrow A5) is adjusted. The drive unit 25T can be said to adjust the tilt angle (tilt angle) of the second lens system 13 in a direction corresponding to the non-scanning direction of the illumination area 35.

As the drive units 23 to 25T, for example, a drive device for displacing a flange portion of an optical member to be driven by a drive element such as an electric micrometer or a piezo element can be used. In this case, each of the drive units 23 to 25T incorporates an encoder (such as a rotary encoder) (not shown) indicating an amount of displacement of the optical member within a drivable range (drive stroke). Is supplied to the drive system 26 of FIG. 1 and the drive system 26 is driven by the second fly-eye lens 9 and the first lens system via drive units 23 to 25T based on the detection signal and the drive information from the main control system 22. 12 and the state of the second lens system 13 are controlled. Note that, for example, a capacitance sensor or the like may be used as the encoder for the drive units 23 to 25T.

In the present embodiment, when performing modified illumination, FIG.
As shown in (a), the first fly-eye lens 6 is changed to a diffractive optical element (Diffractive Optical El
ement: DOE). The light amount distribution conversion element 55
It corresponds to an optical element for setting an exposure beam to a local area.

In FIG. 6A, when performing modified illumination, as an example, an annular aperture stop 10b (or an aperture stop 10 for quadrupole illumination) is formed on the exit surface of the second fly-eye lens 9.
c) is installed, and the light quantity distribution conversion element 55 condenses the exposure light IL to a substantially annular area on the incident surface of the second fly-eye lens 9 by the diffraction effect. The light quantity distribution conversion element 55 is also included in the illumination optical system ILS. As a result, the utilization efficiency of the exposure light IL is enhanced, and a high illuminance can be obtained on the wafer even when performing modified illumination. At this time, a drive unit 58 for adjusting the position of the second lens system 7B in the optical axis IAX direction, a drive unit 62 for adjusting the position of the first lens system 7A in the two-dimensional direction perpendicular to the optical axis, A drive unit 57 for adjusting the position u of the second lens system 4B of the beam shaping system 5 in the optical axis IAX direction is used.
Driving units 57, 58, and 62 composed of electric micrometers and the like are also provided with encoders, respectively.
The detection signals of these encoders and the main control system 2 shown in FIG.
The drive system 26 is driven based on the drive information
The state of the second lens system 57, the second lens system 7B, and the first lens system 7A can be controlled via 7, 58, and 62.

A plurality of light quantity distribution conversion elements (diffractive optical elements) for generating exposure light IL having different irradiation areas (intensity distributions) on the incident surface of the second fly-eye lens 9 are provided in the exchange device 56, and the illumination is performed. Depending on the condition (that is, the intensity distribution of the exposure light IL on the pupil plane of the illumination optical system, in this example, one of the plurality of aperture stops 10a to 10d arranged in the illumination light path), It is also possible to select a light amount distribution conversion element having a high utilization efficiency and arrange it in the illumination light path. At this time, the first fly-eye lens 6 need not be provided in the replacement device 56.

Referring back to FIG. 1, the reticle R is held by suction on a reticle stage 31.
The reticle base 32 is mounted on the reticle base 32 so as to be able to move at a constant speed in the Y direction and to be finely movable in the X direction, the Y direction, and the rotation direction. Reticle stage 31 (Reticle R) 2
The dimensional position and the rotation angle are measured in real time by a laser interferometer in the drive control unit 34.
Based on the measurement result and the control information from the main control system 22, the drive motor (such as a linear motor or a voice coil motor) in the drive control unit 34
The control of the scanning speed and the position is performed. An evaluation mark plate 33 made of a glass substrate is fixed near the reticle R of the reticle stage 31.

FIG. 3A shows the reticle stage 31 shown in FIG.
FIG. 3A is a plan view showing the reticle R of the reticle stage 31 in the scanning direction SD (Y
The evaluation mark plate 33 is fixed on an opening of a region adjacent to the (direction), and in the region of the evaluation mark plate 33 having substantially the same size as the illumination region 35, for example, thirteen two-dimensional identical parts having a substantially uniform distribution. 36A, 36B,... 36M
Are formed. The evaluation mark 36A has an X-axis mark 37X composed of a line and space pattern arranged at a predetermined pitch in the X direction, and a Y-axis mark 37X composed of a line and space pattern arranged at a predetermined pitch in the Y direction. The two-dimensional mark is a combination of the mark 37Y and a box-in-box mark. In this example, when measuring the amount of collapse of the telecentricity of the exposure light IL, that is, the telecentricity of the illumination optical system, as described later, the reticle stage 31 is driven in the Y direction and the center of the evaluation mark plate 33 ( The center of the evaluation mark 36G) is aligned with the center of the illumination area 35 (optical axis AX), and the evaluation marks 36A, 36B,.
The 6M image is projected on the wafer side via the projection optical system PL. An image 36AP of the evaluation mark 36A is shown in the enlarged view of FIG.

Returning to FIG. 1, the wafer W
The wafer stage 39 is attracted and held on the wafer stage 39 through the projection optical system 8 on the wafer base 40.
It moves two-dimensionally along an XY plane parallel to the image plane of L. That is, the wafer stage 39 moves at a constant speed in the Y direction on the wafer base 40, and moves stepwise in the X direction and the Y direction. Further, the position (focus position) of the wafer W in the Z direction, the X axis and the Y
A Z-leveling mechanism for controlling the tilt angle around the axis is also incorporated, and a multipoint autofocus sensor (not shown) for measuring a focus position at a plurality of measurement points on the surface of the wafer W is also provided. . At the time of exposure, the surface of the wafer W is focused on the image plane of the projection optical system PL by driving the Z leveling mechanism by the autofocus method based on the measurement value of the autofocus sensor. Further, at the time of measuring the illumination characteristics, for example, the Z-leveling mechanism in the wafer stage 39 is driven based on the measurement value of the auto focus sensor to control the focus position on the upper surface of the wafer stage 39 by an arbitrary amount. be able to.

The positions of the wafer stage 39 in the X and Y directions and the rotation angles around the X, Y, and Z axes are measured in real time by a laser interferometer in the drive control unit 41. The drive motor (such as a linear motor) in the drive control unit 41 controls the scanning speed and the position of the wafer stage 39 based on the measurement result and the control information from the main control system 22.

The main control system 22 includes a reticle stage 31,
And various information such as the moving position, moving speed, moving acceleration, and position offset of the wafer stage 39 are sent to the drive control units 34 and 41. At the time of scanning exposure, the reticle R is moved in the + Y direction (or -Y direction) with respect to the illumination area 35 of the exposure light IL via the reticle stage 31.
In synchronization with the scanning at the speed Vr, the exposure area 35P of the pattern image of the reticle R via the wafer stage 39.
Of the wafer W in the −Y direction (or + Y direction)
Scanning is performed at Vr (β is a projection magnification from the reticle R to the wafer W). At this time, at the start and end of the scanning exposure, the drive control unit 34 controls the opening and closing operation of the movable blind 14B in order to prevent unnecessary portions from being exposed.

Further, the main control system 22 reads from the exposure data file various exposure conditions for scanning and exposing the photoresist in each shot area on the wafer W with an appropriate exposure amount, and optimizes the exposure conditions in cooperation with the exposure control unit 21. A simple exposure sequence. That is, when a command to start scanning exposure to one shot area on the wafer W is issued from the main control system 22 to the exposure control unit 21, the exposure control unit 21
Starts the emission of the exposure light source 1 and calculates the integrated value of the illuminance (the sum of the pulse energy per unit time) of the exposure light IL to the wafer W via the integrator sensor 20. The integrated value is reset to 0 at the start of the scanning exposure. Then, the exposure control unit 21 sequentially calculates the integrated value of the illuminance, and according to the result, sets the exposure light source 1 so that an appropriate exposure amount can be obtained at each point of the photoresist on the wafer W after the scanning exposure. (Oscillation frequency and pulse energy) and the dimming rate of the variable dimmer 3 are controlled. Then, at the end of the scanning exposure on the shot area, the emission of the exposure light source 1 is stopped.

In the vicinity of the wafer holder 38 on the wafer stage 39 of this embodiment, an uneven illuminance sensor 42 comprising a photodetector and having a pinhole-shaped light receiving portion 42a (see FIG. 4A) is installed. The detection signal S2 of the uneven illuminance sensor 42 is also supplied to the exposure control unit 21. The uneven illuminance sensor 42 has a pinhole-shaped light receiving portion 42a.
Instead of, or in combination with, a light receiving unit such as a line sensor or a CCD extending in the scanning direction (Y direction) of the wafer W with respect to the exposure area 35P may be used. In this case, the illuminance may be integrated in the scanning direction at each position in the non-scanning direction (X direction) orthogonal to the scanning direction in the exposure area 35P, and the illuminance distribution in the non-scanning direction may be obtained based on the integrated value. Accordingly, the illuminance distribution in the non-scanning direction (illuminance unevenness) in consideration of the averaging effect of the illuminance unevenness in the scanning direction due to the scanning exposure, that is, the exposure amount distribution (irradiation amount unevenness) in the non-scanning direction on the wafer after the scanning exposure. ) Can be obtained. Therefore, optimization of illumination characteristics (correction of illuminance unevenness) described later may be performed using the measurement result. Incidentally, by moving the wafer stage 39 two-dimensionally at the time of illuminance measurement, the same illuminance distribution can be obtained even by using the pinhole-shaped light receiving section 42a.

Although not shown, a dose monitor having a light receiving portion covering the entire exposure area 35P is also provided, and a detection signal of the dose monitor and the integrator sensor 20 are provided.
Is calculated from the detection signal of the integrator sensor 20 to indirectly obtain the illuminance on the wafer W from the detection signal. Further, a scanning plate 4 made of a glass substrate is provided near the wafer holder 38 on the wafer stage 39.
3, a substantially square opening pattern 43a is formed in the light shielding film on the scanning plate 43. The condensing lens 4 is provided on the bottom side of the scanning plate 43 in the wafer stage 39.
4 and a photoelectric detector 45 are arranged, and the scanning plate 43, the condenser lens 44, and the aerial image measuring system 46 are provided by the photoelectric detector 45.
The detection signal S3 of the photoelectric detector 45 is supplied to a calculation unit in the exposure control unit 21.

The aerial image measurement system 46 has only a part thereof (for example, at least a part of the light transmission system including the scanning plate 43 and the condenser lens 44 in this example) provided on the wafer stage 39. , The remaining components (photoelectric detector 45, etc.)
May be arranged outside the wafer stage 39. Also,
The aerial image measurement system 46 includes one open pattern 4 on the scanning plate 43.
3a is formed, and at the time of measuring the illumination characteristics described later,
The wafer stage 39 is two-dimensionally stepped, and a plurality of wafer stages 39 (13 in this example) are arranged in the illumination area 35.
Aperture pattern 43a in the scanning direction and the non-scanning direction (Y direction and X direction) for each of the evaluation mark images.
For example, the plurality of evaluation marks and the same number of aperture patterns 43a are formed on the scanning plate 43, and the relative movement between the image of the evaluation marks and the aperture pattern in the scanning direction and the non-scanning direction are performed. When the image of the evaluation mark and the aperture pattern move relative to each other, the images of the plurality of evaluation marks may be collectively detected.

Further, of the plurality of evaluation marks, for example, the same number of aperture patterns 43a as the plurality (five in this example) of evaluation marks separated in the non-scanning direction are formed on the scanning plate 43 along the non-scanning direction. Then, the wafer stage 39 may be moved in the scanning direction, and the images of the evaluation marks arranged in the scanning direction may be continuously detected for each opening pattern. The same number of open patterns 43a as the evaluation marks may be formed on the scanning plate 43, and the wafer stage 39 may be moved in the non-scanning direction to continuously detect the images of the evaluation marks for each opening pattern. . At this time,
It is preferable that the movable blind 14B be driven in accordance with the movement of the wafer stage 39 so that only a part of the illumination area 35 is irradiated with the exposure light IL during the detection of the plurality of evaluation marks. In the former method, it is necessary to step the wafer stage 39 in the scanning direction when the image of the evaluation mark and the aperture pattern are relatively moved in the non-scanning direction. In the latter method, the evaluation mark is not moved in the scanning direction. When moving the image and the aperture pattern relatively,
Since it is necessary to step the wafer stage 39 in the non-scanning direction, both may be combined and the wafer stage 39 may be moved only once in the scanning direction and once in the non-scanning direction.

For example, as shown in FIGS.
When measuring the position of the image 36AP of the evaluation mark 36A in the Y direction, the opening pattern 43a of the scanning plate 43 is moved before the image 36AP, and then the wafer stage 39 is driven to form the image 36AP with the opening pattern 43a. Scan. At this time, the position information of the wafer stage 39 is also supplied to the exposure control unit 21 via the main control system 22. The arithmetic unit in the exposure control unit 21 converts the detection signal of the photoelectric detector 45 into the wafer stage 39. The position of the image 36AP in the Y direction is calculated from the signal obtained by differentiating the position in the X direction. Similarly, the image 36AP is formed by the opening pattern 43a with X
By scanning in the direction, the position of the image 36AP in the X direction is also calculated, and the position information of the image 36AP in the X and Y directions is supplied to the main control system 22.

Returning to FIG. 1, the evaluation mark plate 33 on the reticle stage 31, the uneven illuminance sensor 42 on the wafer stage 39 side, and the aerial image measurement system 46 measure predetermined illumination characteristics (optical characteristics) of the present invention. It corresponds to the characteristic measurement system. Next, an example of an adjustment operation for optimizing a predetermined illumination characteristic of the illumination optical system of the present example will be described. In this example,
As a first set of the predetermined illumination characteristics, an illumination area 35,
Consequently, the illuminance distribution of the exposure light IL in the exposure region 35P varies (hereinafter, referred to as “illuminance unevenness”), and the reticle R
Of the telecentricity of the exposure light IL (hereinafter referred to as "illumination telecentricity") is selected. This is because these two illumination characteristics have the greatest influence on the image projected by the projection optical system PL and the photoresist on the wafer W.

Then, the uneven illuminance is referred to as a primary component relating to the position in the non-scanning direction (X direction) of the exposure area 35P (this is referred to as an “inclination component”), and a secondary component relating to the position (this is referred to as a “concavo-convex component”). "). That is, assuming that the illuminance is a function PF (X) of the position X, the illuminance PF (X) can be approximated as follows, and the coefficient a is a slope component and the coefficient b is a concavo-convex component. At this time, since the illuminance unevenness component in the scanning direction (Y direction) is averaged by the scanning exposure, it is not particularly evaluated in this example. The uneven component is also a component symmetric with respect to the optical axis (axially symmetric component).

PF (X) = a · X + b · X ² + offset (1) Further, the illumination telecentric is set to the illumination area 35 (the exposure area 35).
P) the inclination components (shift components) c and d corresponding to the average inclination angles of the exposure light in the X and Y directions, and the average inclination with respect to the optical axis of the exposure light in the radial direction. And a magnification component e corresponding to the corner. In this case, in this example, the focus position of the wafer stage 39 is ±
The positions (distortion amounts) of a large number of evaluation mark images are measured at each focus position by the aerial image measurement system 46 at the positions defocused by δ, and the evaluation mark images corresponding to the change amount of the focus position are measured. Can be obtained from the average shift amounts of the evaluation marks, and the magnification component e can be obtained from the average shift amounts of the evaluation marks in the radial direction of the image.

In this example, as described with reference to FIG. 2, the five drive units 23, 24, 25X, 25
A second fly-eye lens 9 via Y and 25T,
Although the states of the first lens system 12 and the second lens system 13 can be controlled, the above-described illumination characteristics can be controlled almost independently as described below. (A2) Position adjustment of the second fly-eye lens 9 in the optical axis direction by the first drive unit 23: magnification component e [mrad] of the illumination telecentric; (b2) first lens system 12 by the second drive unit 24
Position adjustment in the optical axis direction: unevenness component b [%] of uneven illuminance, (c2) second lens system 1 by third drive unit 25X
(3) X-direction position adjustment: X-direction tilt component of illumination telecentric c [mrad], (c3) Second lens system 1 by fourth drive unit 25Y
(3) Position adjustment in y direction: tilt component d [mrad] of illumination telecentric in Y direction, (d2) Second lens system 1 by fifth drive unit 25T
3. Tilt angle adjustment: Non-scanning direction tilt component a of uneven illuminance
[%].

As described above, in this example, when the state of the corresponding optical member is controlled by any one of the plurality of drive units 23 to 25T, substantially only one kind of illumination characteristic (optical The combination of the optical members that can control the state so that only the characteristic changes and other illumination characteristics do not change is optimized. As a result, automatic adjustment of the illumination characteristics can be performed with simple control and with high accuracy. Further, by setting the number of drive units to five, all the basic lighting characteristics can be automatically controlled. However, when the illumination characteristic of the control target is only the illumination telecentric, for example, the number and arrangement of the drive units change according to the illumination characteristic of the control target, such as three drive units.

Incidentally, since there is a possibility that the other driving characteristics may be slightly affected among the five driving units, it is desirable to consider the effects on the other driving characteristics. Therefore, first, as shown in the flowchart of FIG. 8, the five drive units 23, 24, 25X, 25Y,
A drive rate indicating how much the corresponding illumination characteristic can be changed when 25T is driven by a unit amount is obtained.

That is, in step 101 of FIG. 8, the illumination condition is controlled by controlling the aperture stop plate 10 of FIG. 1 to one of normal illumination, deformed illumination (ring zone illumination or quadrupole illumination), or small σ value illumination. Set to. In the next step 102,
The ith (i = 1 to 1) among the five drive units 23 to 25T
5) The drive unit is selected. Here, it is assumed that the second drive unit 24 corresponding to the first lens system 12 has been selected. In the next step 103, the drive amount d2 of the drive unit 24 is set at the center of the drivable range (d2 =
0), and the first lens system 12 is set at the optical origin, which is the designed position, to measure the illuminance unevenness and the illumination telecentricity.

In order to measure the uneven illuminance, a glass substrate having no pattern is set on the reticle stage 31 instead of the reticle R in FIG. 1, and the illumination area 35 is irradiated with exposure light IL. The exposure area 35P is scanned in the non-scanning direction (X direction) by the light receiving section of the uneven illuminance sensor 42, and the detection signal S2 of the uneven illuminance sensor 42 is taken into the exposure control unit 21. Instead of the glass substrate, an area of the reticle R where no pattern is formed, or an area of the evaluation mark plate 33 where no evaluation mark is formed may be used.

FIG. 4A shows a state in which the exposure area 35P is scanned in the X direction by the light receiving portion 42a of the uneven illuminance sensor 42, and a curve 51A in FIG. The detection signal S2 plotted corresponding to the position of the stage 39) in the X direction is shown. The calculation unit in the exposure control unit 21 of this example approximates the curve 51A to the right side of the equation (1) by the least square method, thereby obtaining the value a1 of the slope component a of the uneven illuminance and the unevenness component b.
Is calculated. The origin in the X direction at this time is the optical axis AX of the projection optical system PL. When the curve 51A is divided into a primary straight line 52A and a secondary curve 53A as shown by a dotted line,
The slope of the straight line 52A becomes a1, and X ^{2 of the} quadratic curve 53A
Becomes b1.

Next, in order to measure the illumination telecentricity, the reticle stage 31 is driven to move the center of the evaluation mark plate 33 to the center of the illumination area 35 in FIG. The scanning plate 43 of the aerial image measurement system 46 is moved near the region 35P. Then, the Z leveling mechanism in the wafer stage 39 is driven to shift the focus position of the scanning plate 43 from the image plane (best focus position) with respect to the projection optical system PL by + δ (δ is a predetermined value within a range where a predetermined resolution can be obtained). (Set), and the irradiation of the exposure light IL is started, and the images 36AP to 36MP of the evaluation marks 36A to 36M of the evaluation mark plate 33 are placed on the wafer stage 39 as shown in FIG. Project. In this state, as described with reference to FIG. 3B, the images 36 are formed by the aperture pattern 43a of the scanning plate 43.
AP to 36MP are scanned in the X direction and the Y direction, and the obtained detection signal S3 is processed by the arithmetic unit in the exposure control unit 21 so that the X of these images 36AP to 36MP is
And the position in the Y direction are calculated, and the calculation result is transmitted to the main control system 22.
To supply. The origin in this case is, for example, the center of the image 36GP of the central evaluation mark 36G.

The movable blind 14B is driven in accordance with the movement of the wafer stage 39, and only a part of the illumination area 35, for example, an evaluation mark to be detected by the aerial image measurement system 46 during the detection operation. It is desirable to irradiate only the exposure light IL. Thus, the evaluation marks 36A-36 measured by defocusing the scanning plate 43 by + δ.
5A are images 54A to 54M on the dotted grid in FIG.
And Although the dotted grid is drawn as a rectangle for convenience of explanation, it may actually be distorted to some extent due to distortion.

Next, the focus position of the scanning plate 43 is set lower than the best focus position by -δ, and the evaluation marks 36A, 36B,.
The positions of the 36M images 36AP to 36MP in the X and Y directions are obtained and supplied to the main control system 22. In FIG. 5A,
In this case, images 36AP to 36MP and images 54A to 54M measured earlier are displayed. In the main control system 22,
As shown in FIG. 5A, the image 54A to 54M when the focus position is defocused by + δ, the image 3 when the focus position is defocused by −δ.
The two-dimensional displacement amounts in the X and Y directions of 6AP to 36MP are obtained as vectors <VA> to <VM>. Also, a simple average value <V1> (= (c
1, d1)) and the average value <V2> (= e1) of the components in the radial direction (R direction) with respect to the origin are shown in FIG.
It is calculated as shown in (c). Average value (c1, d1)
Is an inclination component of the illumination telecentric, and the average value e1 is a magnification component of the illumination telecentric.

Next, in step 104, with the drive amount d2 of the drive unit 24 set to the + end (d2 = d2 _max ) of the drivable range, the illuminance unevenness and the illumination telecentricity are measured. . As a result, FIG.
As shown in the figure, a curve 51B of the detection signal S2 of the uneven illuminance sensor 42 is obtained, and this curve 51B is
And the quadratic curve 53B, the inclination component a2 of uneven illuminance and the unevenness component b2 are obtained. FIG.
(D) Images 36AP-3 of evaluation marks 36A-36M
From the displacement vectors <VA> to <VM> of 6MP,
As shown in FIGS. 5E and 5F, the tilt component (c2, d2) of the illumination telecentric and the magnification component e2 of the illumination telecentric.
Is obtained.

Next, in step 105, with the drive amount d2 of the drive unit 24 set to the negative end (d2 = -d2 _max ) of the drivable range, the measurement of the illuminance unevenness and the illumination telecentricity is performed. Do. In this manner, similarly, the inclination component a3 and unevenness component b3 of the illuminance unevenness, the inclination components (c3 and d3) of the illumination telecentric, and the magnification component e3 are obtained. If it is desired to calculate the drive rate with higher accuracy, it is desirable to set the drive amount of the drive unit 24 to four or more places and measure uneven illuminance and illumination telecentricity.

In the subsequent step 106, the drive unit 24 (first lens system 12) is used by using the above measured values.
Is calculated. For an example, the driving amount d2 0, d2 _max, tilting component a of the illuminance unevenness when set to -d2 _max are respectively a1, a2, a3,
The driving rate ka2 [% / mm] for the inclination component a is as follows. ka2 = [(a2-a1) / d2 _max- (a3-a1) / (2 · d2 _max )] / 2 (2)

Similarly, drive rates kb2 [% / mm] and kc2 for the unevenness component b of the uneven illuminance, the inclination components c and d of the illumination telecentric, and the magnification component e of the illumination telecentric.
[Mrad / mm], kd2 [mrad / mm], ke2 [mrad
/ Mm] is also calculated and stored in the storage unit in the main control system 22. At this time, the dominant value is the unevenness component b of uneven illuminance.
However, only the drive rate kb2 with respect to the threshold value may be stored as it is for other values exceeding a predetermined level, and 0 may be stored for a value within the predetermined level.

Specifically, when the first lens system 12 is driven, the driving rate k for the magnification component e of the illumination telecentric having the same central symmetric (axially symmetric) characteristics as the uneven component b.
e2 may exceed a predetermined level. Step 1 is performed for all the drive units 23 to 25T in this manner.
The operations of 02 to 106 are executed, and the driving rates kai, k
Bi, kci, kdi, and kei (i = 1 to 5) are calculated and stored in the main control system 22 as parameters for each lighting condition. Thereafter, the process proceeds from step 107 to step 108 to determine whether or not the drive rates have been calculated for all necessary lighting conditions. If not completed, the process returns to step 101 to switch the lighting conditions and change the drive rate. Is calculated. Note that, here, the drive rate is calculated for all the lighting conditions, but the present example is not limited to this. For example, the drive rate is calculated for only a part of all the lighting conditions, and the remaining lighting conditions are calculated. As for the condition, the driving rate may be determined by interpolation calculation or the like based on the driving rate of another lighting condition.

At this time, in the case of the second drive unit 24 (first lens system 12), the drive rates ka2, kc2, and kd2 relating to the center asymmetric component are essentially negligible. If these drive rates are higher than a certain value, the first lens system 12 may be decentered or tilted, and these defects can be detected at this stage. Adjustments can be made.

Next, an example of a sequence for automatically adjusting the illumination optical system using the drive rate obtained as described above will be described with reference to the flowchart in FIG. First, in step 111 of FIG. 9, the illumination conditions are selected via the aperture stop plate 10 of FIG. 1, the drive amounts of all the drive units 23, 24, 25X to 25T are set to the neutral positions, and the corresponding optical members are set. Is set to the optical origin. In the next step 112, uneven illuminance and illumination telecentricity are measured as in step 103 of FIG. Then, in step 113, the inclination component (primary component) a and the unevenness component (secondary component) of the illuminance unevenness are obtained by the procedure shown in FIGS.
b is calculated and the tilt component (shift component) of the illumination telecentric
c, d and a magnification component e are calculated. Next Step 11
In FIG. 4, the illuminance unevenness a, b and the illumination telecentric c, d, e
Are within the allowable range, and if any of them are out of the allowable range, the routine proceeds to step 115, where the drive rates kai,
Using kbi, kci, kdi, and kei (i = 1 to 5), five driving units 23 to 23 for calculating the illumination unevenness a and b and the illumination telecentric c, d and e to 0, respectively.
A drive amount di (i = 1 to 5) of 25T is calculated. In this case, the following simultaneous equations may be solved.

-A = ka1 · d1 + ka2 · d2 + ka3 · d
3 + ka4 · d4 + ka5 · d5-b = kb1 · d1 + kb2 · d2 + kb3 · d3 + kb4 · d
4 + kb5 · d5-c = kc1 · d1 + kc2 · d2 + kc3 · d3 + kc4 · d
4 + kc5 · d5-d = kd1 · d1 + kd2 · d2 + kd3 · d3 + kd4 · d
4 + kd5 · d5-e = ke1 · d1 + ke2 · d2 + ke3 · d3 + ke4 · d
4 + ke5 · d5 However, in reality, one or two of these driving rates are not 0 in each row, so that this simultaneous equation can be solved very easily. The calculated driving amount di (i = 1 to 5) is also stored in the storage unit in the main control system 22 as a parameter corresponding to each of the plurality of illumination conditions.

More specifically, both the drive unit 24 and the drive unit 23 affect the unevenness component b of the uneven illuminance and the magnification component e of the illumination telecentric, and both the drive unit 25T and the drive unit 25X have the inclination component of the uneven illuminance. a and the tilt component c of the illumination telecentric,
It is considered that there is a relationship that only Y affects the tilt component d of the illumination telecentric.

Next, the routine proceeds to step 116, where the five drive units 23 to 25T are driven by the calculated drive amounts di (i = 1 to 5). Then step 1
The process proceeds to steps 12 and 113, and the illumination unevenness a and b and the illumination telecentric c, d and e are measured again.
If all the values do not fall within the allowable range, the process returns to step 115 to execute the calculation. If all the values fall within the allowable range, the automatic adjustment ends. Then, when the same lighting conditions are set next,
Drive unit 23 based on the stored drive amount di
The adjustment of the illumination optical system is completed in a very short time only by driving up to 25T.

As described above, in this example, the illumination characteristics can be automatically measured. Therefore, the drive rate measurement sequence of FIG. 8 and the illumination optical system automatic adjustment sequence of FIG. 9 can all be performed without assistance. Next, as shown in FIG. 6A, an aperture stop 10b for annular illumination (or an aperture stop 10c for quadrupole illumination) is installed on the exit surface of the second fly-eye lens 9 in the illumination optical system of the present example. An example of an adjustment method when performing deformed illumination will be described.

In this case, a light quantity distribution conversion element 55 composed of a diffractive optical element (DOE) is provided instead of the first fly-eye lens 6 in FIG. Instead of the diffractive optical element, a prism such as a conical prism (for axicon and annular illumination) or a quadrangular pyramid (pyramid) prism (for quadrupole illumination) may be used. The second aperture stop is used depending on whether the aperture stop used is the aperture stop 10b or 10c.
In order to adjust the irradiation area of the exposure light IL to the fly-eye lens 9, the first lens system 7A can be driven in a direction perpendicular to the optical axis by the drive unit 62, and the second lens system 7B is driven by the drive unit 58 in the optical axis. Be able to drive in the direction. Note that, instead of the condensing optical system (beam shaping optical system) including the lens systems 7A and 7B, a zoom optical system, an optical system that continuously changes aberration, or a cylindrical lens is rotated to deform the beam cross section. Such an optical system may be used.

In the case of the optical system shown in FIG. 6A, depending on the illumination area when the second fly-eye lens 9 is locally illuminated,
It has been confirmed by the present inventors that the illuminance unevenness changes rapidly. Specifically, the change factors of the uneven illuminance can be divided into the following factors. 1) When the local illumination area is small, the image plane illuminance increases because the amount of light passing through the aperture stop is large. However, some of the effective elements of the second fly-eye lens 9 are illuminated halfway, and this causes uneven illuminance. Adversely affect

2) When the local illumination area is large, the illuminance unevenness does not deteriorate, but the amount of light blocked by the aperture stops 10b and 10c naturally increases, and the image plane illuminance decreases. 3) When the local illumination area is decentered, illumination unevenness on the image plane tends to be lower on either the left or right side (tilt component). This is because each element of the second fly-eye lens 9 has a finite size. Therefore,
In this example, when performing modified illumination using the light quantity distribution conversion element 55, a special adjustment sequence is prepared as shown in FIG.

Therefore, in step 121 of FIG. 10, the drive rate measurement of FIG. 8 and the automatic adjustment sequence of FIG. 9 are executed in the state of FIG. In the next step 122, as shown in FIG. 6A, the first fly-eye lens 6 is
And the aperture stop on the exit surface of the second fly-eye lens 9 is set to the aperture stop 10b or 10c for deformed illumination.
In the next step 123, the uneven illuminance sensor 4 of FIG.
2, the illuminance unevenness is measured, and the inclination component a and the unevenness component b are calculated as shown in FIG. At this time, if the illuminance distribution has extreme uneven illuminance on both sides in the non-scanning direction and the inclination component a exceeds the allowable range, the local illumination area may be eccentric as described above. There is. In this case, the first lens system 7A is moved in the X direction and the Y direction in a plane perpendicular to the optical axis so that the tilt component a falls within the allowable range.
Shift in the direction corresponding to the direction.

Then, in this state, the unevenness component b of uneven illuminance
Is to be evaluated. That is, the process proceeds to step 124,
It is determined whether the concavo-convex component b is within the permissible range. If the permissible component b is outside the permissible range, the process proceeds to step 125, where the second lens system 7B is shifted by a predetermined step amount in the optical axis direction, and then returns to step 123. Irregularity unevenness component b again
Is measured, and it is determined whether or not it is within an allowable range. This correction operation is performed until the unevenness component b falls within the allowable range in step 124.

After the concavo-convex component b falls within the allowable range in step 124, the process proceeds to step 126, where FIG.
The lens system 4B of the beam forming system 5 is gradually changed (scanned) by a predetermined amount in the optical axis direction, and the illuminance unevenness sensor 42 of FIG. 1 has no pattern image at each position (position u) of the lens system 4B. Scanning is performed in the non-scanning direction in the exposure area 35 </ b> P, and the data sequence of the detection signal S <b> 2 is taken into the exposure control unit 21, and the detection signal S <b> 1 of the integrator sensor 20 is taken into the exposure control unit 21.

In the next step 127, the lens system 4
At each position u of B, the difference ΔIP between the maximum value and the minimum value of the detection signal S2 (illuminance) is obtained as uneven illuminance, and the magnitude (average value) IP of the illuminance on the image plane is obtained from the detection signal S1 of the integrator sensor 20. Is obtained indirectly. Then, the calculation unit in the exposure control unit 21 associates each position u of the lens system 4B with the reciprocal (1 / ΔIP) of the uneven illuminance ΔIP and the image plane illuminance IP. For clarity, position u
With respect to the image plane illuminance IP and the reciprocal of the illuminance unevenness (1 / ΔI
FIG. 7 is a diagram plotting P).

In FIG. 7, the horizontal axis represents the position u of the lens system 4B, and the vertical axis represents the image plane illuminance IP and the reciprocal (1 / ΔIP) of the illuminance unevenness ΔIP. The curve 59 indicates the image plane illuminance I
P and a curve 60 represent the reciprocal (1 / ΔIP) of the uneven illuminance. In this case, when the image plane illuminance IP increases, the reciprocal (1 / ΔIP) of the illuminance unevenness decreases, and the illuminance unevenness increases. Therefore, it can be seen that there is a trade-off relationship between the image plane illuminance and the illuminance unevenness. Therefore, in this example, the range 61 (u1 ≦ u ≦ u2) of the position u where the image plane illuminance is equal to or more than the allowable value TL1 (position u2) and the reciprocal of the uneven illuminance is equal to or more than the allowable value TL2 (position u1) is set to It is obtained as a settable range of 4B and supplied to the main control system 22.

In the next step 128, the main control system 22 shown in FIG.
The position u of B is set within the settable range 61. As a result, a high image plane illuminance can be obtained and the throughput of the exposure step can be improved, and the illuminance non-uniformity is reduced, and a high imaging accuracy is obtained. Further, when fine random illumination unevenness is measured on the image plane, the random illumination unevenness can be sometimes eliminated by shifting the optical element for deformed illumination in the optical axis direction. As described above, by driving any optical member of the illumination optical system, the characteristics of various illumination optical systems change.However, these are selected at the design stage, and the optimal drive unit is incorporated in the automatic adjustment sequence. Thereby, it is possible to further improve the illuminance unevenness and the driving precision of the illumination telecentric.

In the above embodiment, both the uneven illuminance and the telecentricity are measured (detected), but only one of them may be measured. Furthermore,
In the telecentricity, the tilt component is measured separately in the X direction and the Y direction, but only one of them may be used. Further, in the above embodiment, the illuminance non-uniformity in the non-scanning direction is detected by the scanning exposure type exposure apparatus, but the illuminance non-uniformity is detected in the X direction and the Y direction by the static exposure type exposure apparatus. Preferably, a correction is made.

Further, in each of the above embodiments, the adjustment is performed at the time of measuring the illumination characteristic (at least one of the illumination telecentricity and the uneven illuminance). However, the adjustment of the illumination characteristic may be performed other than at the time of the measurement. . For example, a change in the illumination characteristic may be calculated (simulation or the like), and the illumination characteristic may be sequentially adjusted based on the calculation result. Further, the illumination characteristics may be periodically measured and adjusted, and the illumination characteristics may be adjusted by the above calculation during the periodic measurement. Further, regarding the illuminance unevenness, when the illumination condition, that is, the intensity distribution (especially, the shape) of the exposure light IL on the pupil plane of the illumination optical system is changed, both the inclination component and the centrally symmetric component (unevenness component) of the illuminance unevenness are changed. Until the adjustment is made and then the illumination condition is changed, only the unevenness component may be adjusted.

In FIG. 6A, the light amount distribution conversion element 55 is arranged in the optical path of the exposure light by exchanging the first fly-eye lens 6 at the time of deformed illumination. The light amount distribution conversion element 55 may be arranged between the integrator (the first fly-eye lens 6 in this example). At this time, the light amount distribution conversion element 55 may be replaced with another element that generates a different light amount distribution according to a change in the illumination condition. Also, in the configuration example of FIG. 6A, the light amount distribution conversion element 55 may be replaced between the annular illumination and the quadrupole illumination.

Further, the illumination condition switching system of FIG. 1 includes an aperture stop plate 10, an exchange device 56 for exchanging an optical integrator (first fly-eye lens 6) and a light quantity distribution conversion element (diffractive optical element 55). The illumination condition switching system includes the aperture stop plate 10.
Only, or may include only the exchange device 56,
The exchange device 56 may perform only the exchange of the plurality of light amount distribution conversion elements described above. Further, in combination with at least one of the aperture stop plate 10 and the exchange device 56 or instead of the aperture stop plate 10 and the exchange device 56, for example, a zoom optical system and a pair of relatively movable optical axis directions of the illumination optical system. At least one of a prism (such as a conical prism (axicon) or a quadrangular pyramid prism) may be disposed between the exposure light source 1 and the optical integrator (the second fly-eye lens 9).

Although the fly-eye lenses 6 and 9 are used as optical integrators in the above-described embodiment, the present invention is also applicable to a case where an internal reflection type integrator (rod integrator) is used as an optical integrator. What you can do is clear. Further, in the above embodiment, a so-called double fly-eye type illumination optical system ILS using two-stage fly-eye lenses 6 and 9 is used, but a one-stage optical integrator (fly-eye lens, rod integrator) is used. The present invention can also be applied to a case where adjustment of an illumination optical system using only the above-described method is performed. Further, the above-described diffractive optical element (DOE) may be used as an optical integrator not only for modified illumination but also for ordinary illumination and illumination with a small σ value. Of course, in this case, it is desirable to prepare a plurality of diffractive optical elements and replace them according to the illumination conditions.

As the optical integrator (9), for example, an internal reflection type integrator in which the entrance plane is arranged on the pupil plane of the illumination optical system and the exit plane is arranged conjugate with the pattern plane of the reticle R, and Between the exposure light source 1 and the optical integrator (9),
When an optical unit including at least one of the plurality of light amount distribution conversion elements (diffractive optical elements), the zoom optical system, and the pair of prisms described above is arranged, when the illumination condition is changed,
The incident angle range of the exposure light IL incident on the internal reflection type integrator is changed. When a fly-eye lens is used as the optical integrator (9), a surface light source composed of a plurality of light source images, that is, a secondary light source is formed on the exit surface thereof, and when an internal reflection type integrator is used, its entrance surface is used. Consisting of multiple virtual images
A secondary light source is formed. Therefore, the change of the illumination condition in each of the above embodiments means that the exposure light I on the pupil plane of the illumination optical system is changed.
It is equivalent to changing the intensity distribution of L and changing at least one of the size and shape of the secondary light source formed on the pupil plane of the illumination optical system.

In the above embodiment, the present invention is applied to a scanning exposure type projection exposure apparatus, but the present invention is applied to a step-and-repeat type (batch exposure type).
The present invention can also be applied to a projection exposure apparatus (stepper) described above and an exposure apparatus of a proximity system or the like that does not use a projection system. Further, the exposure light (exposure beam) is not limited to the above-described ultraviolet light, and may be, for example, a laser plasma light source or an S beam.
EUV light in the soft X-ray region (wavelength 5 to 50 nm) generated from an OR (Synchrotron Orbital Radiation) ring may be used. In the EUV exposure apparatus, the illumination optical system and the projection optical system each include only a plurality of reflection optical elements.

Then, semiconductor devices can be manufactured from the wafer W of FIG. The semiconductor device has a step of designing the function and performance of the device, a step of manufacturing a reticle based on this step, a step of manufacturing a wafer from a silicon material, and a step of forming a reticle pattern on the wafer by the projection exposure apparatus of the above-described embodiment. , A device assembling step (including a dicing step, a bonding step, and a package step), an inspection step, and the like.

The application of the exposure apparatus is not limited to an exposure apparatus for manufacturing a semiconductor device. For example, an exposure apparatus for a liquid crystal display element formed on a square glass plate or an exposure apparatus for a display apparatus such as a plasma display. The present invention can be widely applied to an apparatus and an exposure apparatus for manufacturing various devices such as an imaging device (CCD or the like), a micromachine, a thin-film magnetic head, and a DNA chip. Further, the present invention can be applied to an exposure step (exposure apparatus) when manufacturing a mask (photomask, reticle, or the like) on which a mask pattern of various devices is formed by using a photolithography step.

The present invention is not limited to the above-described embodiment, but can take various configurations without departing from the gist of the present invention.

[0090]

According to the present invention, the illumination system (illumination optical system) of the exposure apparatus can be accurately adjusted in a short time.
When a characteristic measurement system for measuring the illumination characteristics of the illumination system is provided, adjustment of the illumination system having a plurality of illumination conditions can be automatically performed. In addition, when the inclination component and the magnification component of the amount of collapse of the telecentricity of the exposure beam (telecentricity of the illumination system) are separately measured as the illumination characteristics, the adjustment can be performed in a short time by adjusting both independently. Can be done accurately.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing a projection exposure apparatus according to an example of an embodiment of the present invention.

FIG. 2 is a perspective view showing an optical system from a second fly-eye lens 9 to a second lens system 13 and an illumination area 35 in FIG.

3A is a plan view showing a reticle stage 31 and an evaluation mark plate 33, and FIG. 3B is an image 36 of an evaluation mark.
FIG. 3 is an enlarged plan view for explaining an AP detection method.

FIG. 4 is an explanatory diagram of a method for measuring a tilt component and an uneven component of uneven illuminance.

FIG. 5 is an explanatory diagram of a method of measuring a tilt component and a magnification component of an illumination telecentric.

FIG. 6A is a partially cutaway view showing a main part when performing modified illumination in the illumination optical system ILS of FIG. 1;
FIG. 7B is a front view showing the aperture stop plate 10 of FIG.

FIG. 7 is a diagram illustrating an example of a relationship between illuminance magnitude and illuminance unevenness when performing modified illumination.

FIG. 8 is a flowchart illustrating an example of a measurement sequence of drive rates of all drive units in the illumination optical system.

FIG. 9 is a flowchart illustrating an example of an automatic adjustment sequence of the illumination optical system.

FIG. 10 is a flowchart illustrating an example of an adjustment sequence for modified illumination.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Exposure light source, 5 ... Beam shaping system, 6 ... 1st fly-eye lens, 9 ... 2nd fly-eye lens, 10 ... Aperture stop plate, 12 ... 1st lens system, 13 ... 2nd lens system, 14A
... fixed blind, R ... reticle, PL ... projection optical system,
W: wafer, 20: integrator sensor, 21: exposure control unit, 22: main control system, 23, 24, 25X,
25Y, 25T: drive unit, 26: drive system, 31 ...
Reticle stage, 33 ... Evaluation mark plate, 36A-36
M: evaluation mark, 42: uneven illuminance sensor, 46: aerial image measurement system, 55: light intensity distribution conversion element

Claims (21)

[Claims] 1. An exposure apparatus, comprising: an illumination system that illuminates a first object with an exposure beam; and an exposure apparatus that exposes a second object via the first object with the exposure beam. An illumination condition switching system for switching the illumination condition of the exposure beam to any one of a plurality of illumination conditions; and in order to control a predetermined illumination characteristic of the illumination system in accordance with each of the plurality of illumination conditions, An exposure apparatus, comprising: an adjustment system for adjusting a state of a predetermined optical member. 2. The exposure apparatus according to claim 1, wherein the illumination characteristic is at least one of uneven illuminance of the exposure beam and an amount of collapse of the telecentricity of the exposure beam. 3. The illumination device according to claim 2, wherein the illumination characteristics are a slope component and a concavo-convex component of uneven illuminance of the exposure beam, and a slope component and a magnification component of a telecentricity loss amount of the exposure beam. Exposure apparatus according to the above. 4. A characteristic measurement system for measuring the illumination characteristics of the illumination system, and a relationship between a drive amount of the adjustment system and a change amount of the illumination characteristics is determined based on a measurement result of the characteristic measurement system. 4. The exposure apparatus according to claim 1, further comprising an arithmetic control system for storing. 5. An exposure apparatus, comprising: an illumination system for illuminating a first object with an exposure beam; and exposing a second object via the first object with the exposure beam, wherein a predetermined illumination characteristic of the illumination system is measured. An exposure apparatus, comprising: a characteristic measurement system that performs a measurement; and an adjustment system that adjusts a state of a predetermined optical member in the illumination system in accordance with a measurement result of the characteristic measurement system. 6. The illumination system according to claim 1, wherein the illumination system has an optical integrator, and the adjustment system adjusts a position of the optical integrator in an optical axis direction.
The exposure apparatus according to claim 1. 7. The illumination system further includes a first optical system and a second optical system that guide the exposure beam having passed through the optical integrator to a surface to be irradiated of the first object or a surface conjugate to the surface. The adjustment system has a position in the optical axis direction of the optical integrator, a position in the optical axis direction of the first optical system, and a position and a tilt angle in a direction perpendicular to the optical axis of the second optical system. The exposure apparatus according to claim 6, wherein the adjustment is performed. 8. An illumination system, comprising: an optical element for setting an illuminance distribution of the exposure beam to a local area for deformed illumination; a condensing optical system for guiding an exposure beam from the optical element; An optical integrator for equalizing the illuminance distribution of the exposure beam from the converging optical system, wherein the adjusting system adjusts a state of an optical member constituting the converging optical system. The exposure apparatus according to claim 1. 9. The illumination system includes a beam shaping optical system that shapes an exposure beam from an exposure light source and guides the beam to the optical element; and a magnitude of illuminance of the exposure beam and a variation in illuminance distribution of the exposure beam. 9. The exposure apparatus according to claim 8, wherein the state of the beam shaping optical system is adjusted by the adjustment system so that the size of the beam shaping optical system is balanced. 10. An illumination system for illuminating a first object with an exposure beam, and a second system through the first object with the exposure beam.
An exposure apparatus for exposing an object, wherein an amount of collapse of telecentricity of the exposure beam in the illumination system is measured separately for a tilt component and a magnification component. 11. The exposure apparatus according to claim 10, wherein the illuminance unevenness of the exposure beam by the illumination system is measured separately for a tilt component and a concavo-convex component. 12. A first movable body on which the first object is mounted and a second movable body on which the second object is mounted, wherein the first and second movable bodies are synchronously driven. The exposure apparatus according to claim 1, further comprising a driving system, wherein the exposure apparatus scans and exposes the second object with the exposure beam via the first object. 13. A scanning direction in which the exposure beam is detected on a predetermined surface on which the second object is arranged, and the first and second objects are moved during the scanning exposure within an irradiation area of the exposure beam. 13. The exposure apparatus according to claim 12, wherein a slope component of illuminance unevenness in a non-scanning direction orthogonal to the direction is measured. 14. An unevenness component of the uneven illuminance and the non-scanning direction based on an integrated distribution in the non-scanning direction obtained by integrating illuminance or light amount in the scanning direction within an irradiation area of the exposure beam. 14. The exposure apparatus according to claim 13, wherein a tilt component related to the exposure is determined. 15. The method according to claim 1, wherein an exposure beam applied to a mark provided on the first movable body other than the first object is detected, and an amount of collapse is measured.
15. The exposure apparatus according to 2, 13, or 14. 16. A method for adjusting an exposure apparatus that irradiates a first object with an exposure beam passing through an illumination system and exposes a second object with the exposure beam via the first object, wherein the second object is arranged Detecting the exposure beam on a predetermined surface, measuring the illumination characteristics including at least one of the telecentricity of the illumination system and the distribution of illuminance or light amount in the irradiation area of the exposure beam, Driving an optical member in the illumination system based on the measured illumination characteristics, and updating the measured illumination characteristics by calculation until the next measurement of the illumination characteristics, and updating the updated illumination characteristics A method for adjusting the exposure apparatus, wherein the optical member is driven based on the condition. 17. The exposure beam is driven via the first object by synchronously driving a first movable body on which the first object is mounted and a second movable body on which the second object is mounted. The second
17. The method according to claim 16, wherein the object is scanned and exposed, and the illumination characteristic is measured using a mark provided on the first movable body other than the first object. 18. A scanning direction in which the exposure beam is detected on a predetermined surface on which the second object is arranged, and the first and second objects are moved during the scanning exposure within an irradiation area of the exposure beam. 18. The method according to claim 17, wherein a slope component of illuminance unevenness in a non-scanning direction orthogonal to the scan direction is measured. 19. An illumination system for illuminating a first object with an exposure beam, and a second system through the first object with the exposure beam.
In the method of adjusting an exposure apparatus that exposes an object, a state of a predetermined optical member in the illumination system is set to a plurality of states, and a predetermined illumination characteristic of the illumination system is measured, based on the measurement result. Determining and storing a relationship between the drive amount of the optical member and the change amount of the illumination characteristic, and driving the optical member to control the illumination characteristic based on the stored relationship. Adjustment method of exposure apparatus. 20. An illumination condition of the illumination system can be switched to any one of a plurality of illumination conditions, and an optimum position of the optical member is obtained and stored for each of the plurality of illumination conditions. 20. The method according to claim 19, wherein when the illumination condition of the illumination system is switched, the position of the optical member is set to an optimal position with respect to the switched illumination condition. 21. A device manufacturing method including a step of transferring a device pattern onto a workpiece using the exposure apparatus according to claim 1. Description: