JPH11260712A - Aligner and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent heat generated from an imaging characteristic mechanism from giving effect on imaging characteristics, etc., of a projection optical system. SOLUTION: A drive element controller 53 transfers signals with a main controller MC to judge whether or not the aligner is now in its optical aligning operation. When judging that the aligner is in the optical aligning operation, the controller 53 calculates target positions of a lens element 21, etc., on the basis of calculation parameters received from the main controller MC, and servo-drives drive elements 25, 27 and 29 to displace the lens element 20, etc., to these target positions. When judging that the aligner is not in the aligning operation, the element controller 53 calculates reference positions of the lens element 21, etc., on the basis of the parameters received from the main controller MC, stops the servo-driving operation of the elements 25, 27 and 29, and locks the lens element, etc., to the reference positions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus and an exposure method for manufacturing semiconductor integrated circuits and liquid crystal devices, which require high-precision imaging performance, and more particularly to maintaining the imaging performance of a projection optical system. is there.

[0002]

2. Description of the Related Art An exposure apparatus is used in a photolithography process for forming a circuit pattern of a semiconductor element or the like.
The image of the pattern formed on the reticle (mask) is transferred to a photoresist-coated photosensitive substrate via a projection optical system.

In this type of exposure apparatus, it has been required to maintain the imaging characteristics of the projection optical system at a constant value with high accuracy, and various methods for correcting the imaging characteristics have been proposed and put into practical use. Has been

[0004] Among them, a method of compensating for the fluctuation of the imaging characteristic due to the exposure light absorption of the projection optical system is disclosed in, for example, Japanese Patent Application Laid-Open No. 5-251299. In this method, the amount of heat accumulated in the projection optical system in accordance with the incidence of the exposure light on the projection optical system is sequentially calculated in consideration of the illumination condition of the reticle by the illumination optical system, and the imaging characteristic based on the accumulated energy amount is calculated. The amount of change is obtained, and the imaging characteristics are finely adjusted by a predetermined correction mechanism. In such a correction mechanism, for example, two of the plurality of lens elements constituting the projection optical system are used.
One lens element is independently driven with respect to the reticle using a piezo element or the like.

[0005]

However, in the above-mentioned prior art, since the correction mechanism such as the piezo element is always operated after the exposure process is started, the heat generated from the piezo element cannot be ignored. In some cases, this may have an adverse effect on the imaging characteristics of the projection optical system, the accuracy of a measuring device disposed around the projection optical system, and the like.

Accordingly, the present invention provides an exposure apparatus capable of preventing the heat generated from the above-mentioned correction mechanism from affecting the imaging characteristics of the projection optical system and operating the correction mechanism efficiently. With the goal.

[0007]

Hereinafter, an exposure apparatus and method according to the present invention will be described with reference to the accompanying drawings for explaining the embodiments.

An exposure apparatus according to the present invention includes an illumination optical system (IS) for irradiating illumination light from a light source (OS) to a mask pattern (R), and an image of the mask pattern on a photosensitive substrate (W).
Optical system (PL) for image-forming and projecting the image on the optical system, and a correction device (25, 27) for displacing predetermined optical elements (20, 21, 22) constituting the image-forming optical system to correct the imaging characteristics An exposure apparatus comprising: a servo drive unit that shifts the predetermined optical element to a predetermined target position during the exposure process, and stops the servo drive of the correction device during the non-exposure process. A control device (53) for causing the control device to perform the control.

An exposure apparatus according to another aspect includes an illumination optical system (IS) for irradiating illumination light from a light source (OS) to a mask pattern (R), and an image of the mask pattern on a photosensitive substrate (W). An imaging optical system (PL) for forming and projecting an image, and predetermined optical elements (20, 21,
Correction device (2) for correcting the imaging characteristics by displacing
5, 27), wherein during the exposure process, the correction device is servo-driven to displace the predetermined optical element to a predetermined target position, and during the non-exposure process, the servo drive of the correction device is performed. And a second operation mode in which the correction device is servo-driven to displace the predetermined optical element to a predetermined target position during both the exposure processing and the non-exposure processing. A control device (53) is provided.

In a preferred aspect of the present invention, when the control device (53) stops the servo drive of the correction device, the predetermined optical element (20, 21, 22) is moved to a predetermined reference position. It is characterized by holding.

In a preferred aspect of the present invention, when the control device (53) has a possibility that a heating value at the time of servo-driving the correction device may exceed a predetermined allowable heating value,
The first operation mode is selected.

Further, in a preferred aspect of the present invention, when the control device (53) has a possibility that a heat generation fluctuation amount when the correction device is servo-driven exceeds a predetermined allowable fluctuation amount, the control device (53) may execute the second operation mode. Is selected.

[0013] In a preferred aspect of the present invention, the control device (53) judges switching between the first and second operation modes when the illumination condition of the illumination optical system is changed. I do.

Further, according to the exposure method of the present invention, the image of the mask pattern (R) is transferred onto the photosensitive substrate (W) via the imaging optical system while correcting the imaging characteristics of the imaging optical system (IS). An exposure method for transferring, wherein during an exposure process, predetermined optical elements (20, 21, 22) constituting the imaging optical system are displaced to a target position to correct an imaging characteristic, and during an exposure process, Is
The (20, 21, 22) displacement of the predetermined optical element is stopped.

According to another aspect of the present invention, there is provided an exposure method, wherein an image of a mask pattern (R) is transferred to a photosensitive substrate (W) through the imaging optical system while correcting the imaging characteristics of the imaging optical system (IS). An exposure method of transferring the predetermined optical element constituting the imaging optical system to a target position during the exposure processing to correct the imaging characteristic and correct the imaging characteristic during the non-exposure processing. A first operation mode in which displacement is stopped and a second operation mode in which the predetermined optical element is displaced to a target position to correct an imaging characteristic during the exposure processing and the non-exposure processing are selectively switched and executed. It is characterized by doing.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an exposure apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

[1. Configuration of Exposure Apparatus] FIG. 1 is a side view showing a schematic configuration of an exposure apparatus. This exposure apparatus
A light source device OS for generating illumination light for exposure and a light source device O
Illumination optical system IS for irradiating illumination light from S onto reticle R
And a reticle stage device RS for supporting the reticle R and moving the reticle R to an appropriate position, and a projection optical system PL for projecting a pattern formed on the reticle R onto the wafer W.
And supports the wafer W and projects it on the projection optical system PL.
A wafer stage apparatus WS for moving the wafer stage to an appropriate position;
And a main control device MC for integrally controlling these.

First, the light source device OS will be described. Illumination light generated from the ultra-high pressure mercury lamp 1, which is a light source,
The light is converged on the second focal point f ₀ by the elliptical mirror 2. In the vicinity of the second focal point f _0, it is arranged rotary shutter 3. The rotary shutter 3 is driven by the motor 4 to rotate, and turns on / off the output of the illumination light IL from the light source device OS.

The ultra-high pressure mercury lamp 1 has illumination light IL in a wavelength range (for example, i-line) to which the resist layer on the wafer W is exposed.
Occurs. Note that a laser beam from a light source such as a KrF or ArF excimer laser may be used instead of the bright line of the ultra-high pressure mercury lamp 1.

Hereinafter, the illumination optical system IS will be described.
The illumination light IL emitted from the light source device OS is reflected horizontally by the cold mirror 5, collimated by the collimator lens 6, enters the optical integrator 7, and forms a secondary light source at the emission end of the optical integrator 7. .
A variable aperture stop 8 is arranged on the emission end side of the optical integrator 7. The illumination light IL that has passed through the variable aperture stop 8 passes through the relay lenses 9 and 11 and the main condenser lens 12, is reflected downward by the mirror 13, and is then disposed between the relay lenses 9 and 11. The illumination area on the reticle R defined by the field stop 10 is illuminated with substantially uniform illuminance.

As shown in FIG. 2, the optical integrator 7 has four types of fly-eye lens groups 7a to 7d fixed to a turret plate 7f. By rotating the turret plate 7f by the drive system 54, any one of the four types of fly-eye lens groups 7a to 7d can be arranged in the optical path of the illumination optical system IS, and another fly-eye lens group can be arranged as necessary. It can be replaced with the eye lens groups 7a to 7d. The fly-eye lens groups 7a to 7d are arranged so that the eccentric state of the illumination optical system IS with respect to the optical axis AX is different. When any one of the fly-eye lens groups 7a to 7d is disposed in the optical path of the illumination optical system IS, the center CT thereof substantially coincides with the optical axis AX of the illumination optical system IS. Thereby, the fly-eye lens groups 7a to 7d required according to the arrangement direction of the pattern formed on the reticle R and the like.
Can be selected and arranged in the optical path of the illumination optical system IS.

Since the surface of the variable field stop 10 is in a conjugate relationship with the reticle R, a plurality of movable blades constituting the variable field stop 10 are opened and closed by a motor (not shown) to reduce the size and shape of the opening. By changing, reticle R
Can be set arbitrarily.

Hereinafter, the reticle stage device RS will be described. The reticle R is held by a reticle holder 14, and the reticle holder 14 is placed on a stage 15 that can move two-dimensionally in a horizontal XY plane via a plurality of drive elements 29 that can expand and contract. . By controlling each expansion and contraction amount of the driving element 29 from the driving element control unit 53, the reticle R can be translated in the Z direction parallel to the optical axis AX, and can be moved with respect to an XY plane perpendicular to the optical axis AX. It can be tilted in any direction. This makes it possible to correct the imaging characteristics of the projection optical system PL, in particular, pincushion and barrel distortions. The bar code reader 52 reads the reticle R identification bar code BC formed on the side of the pattern area PA of the reticle R while the reticle R is being conveyed immediately above the projection optical system PL.

Hereinafter, the projection optical system PL will be described.
The illumination light IL that has passed through the pattern area PA formed on the reticle R enters a projection optical system PL that is telecentric on both sides. The projection optical system PL superimposes and projects a projection image of the circuit pattern formed in the pattern area PA onto one shot area on the wafer W held so that the surface substantially matches the best imaging plane. Image).

In this embodiment, the first group lens element 20 and the second group lens elements 21 and 22, which are some of the optical elements constituting the projection optical system PL, are driven by the drive element control unit 53 to project the projection optical system. It can be driven independently of the main body of the PL. Thereby, it is possible to correct the imaging characteristics of the projection optical system PL, for example, the projection magnification, distortion, and the like. Further, the projection optical system PL
Of the variable aperture stop 3 in the pupil plane Ep or in the vicinity thereof
2, the numerical aperture NA of the projection optical system PL can be changed.

Hereinafter, the wafer stage apparatus WS will be described. The wafer W is placed in a wafer holder (θ table) 16.
To the stage 17 via the holder 16.
Is held on. The stage 17 can be tilted in any direction with respect to the best image forming plane of the projection optical system PL by the motor 18 and can be finely moved in the Z direction parallel to the optical axis AX, and emits light in a step-and-repeat manner. Axis AX
2D can be moved two-dimensionally in the X-Y direction perpendicular to. That is, when the transfer exposure of the reticle R to one shot area on the wafer W ends, the stage 17 moves stepwise to the next shot position.

The end of the stage 17 has an interferometer 4
The movable mirror 43 that reflects the laser beam from the stage 2 is fixed, and based on the output signal of the interferometer 42, the stage 17
Is always detected in the XY plane.

The photoelectric sensor 3 is mounted on the stage 17.
3 is provided so as to substantially coincide with the surface position of the wafer W. The photoelectric sensor 33 is composed of, for example, a photodetector having a light receiving surface having substantially the same area as the image field of the projection optical system PL or the projection area of the reticle pattern, and outputs light information on the irradiation amount to the main controller MC. I do.
This optical information is transmitted to the projection optical system P with the incidence of the illumination light IS.
It becomes basic data for obtaining a change amount (aberration amount or the like) of the imaging characteristic corresponding to the amount of energy stored in L.

Further, an irradiation optical system 30 for causing an image forming light beam for forming a pinhole or a slit image on the best image forming plane of the projection optical system PL to be obliquely incident on the optical axis AX.
And a light receiving optical system 31 for receiving the reflected light beam of the image forming light beam on the surface of the wafer W. In this focus detection system, a positional shift in the vertical direction (optical axis AX direction) of the surface of the wafer W with respect to the imaging plane is detected, and the focus state of the projection optical system PL on the wafer W is detected.

Hereinafter, main controller MC will be described.
Although not shown, the main controller MC controls the change of the illumination conditions and the start and stop of the exposure operation, and a control unit for controlling the entire apparatus, and the amount of change in the imaging conditions for each illumination condition and reticle pattern. A calculation unit for determining the allowable limit value of the reticle R and calculating the amount of change in the imaging characteristic, and operating parameters corresponding to the name of each of the plurality of reticles R, such as illumination conditions and heat accumulation amount of the projection optical system (or And a storage unit (memory) for storing calculation parameters and the like for calculating the amount of change in the imaging characteristic corresponding to (i).

In the main controller MC, the names of a plurality of reticles R to be handled by the exposure apparatus and the operation parameters of the exposure apparatus corresponding to each name are registered in advance. The main control device MC includes a bar code reader 52.
Reads the reticle bar code BC, the fly-eye lens group that most closely matches the pre-registered illumination conditions (corresponding to the type of reticle, periodicity of the reticle pattern, etc.) as one of the operation parameters corresponding to the name 7a ~
7d, and outputs a predetermined drive command to the drive system 54. Further, as operation parameters corresponding to the above-mentioned names, optimal setting conditions of the variable aperture stops 8, 32 and the variable field stop 10 under the fly-eye lens groups 7a to 7d selected previously, and the projection optical system PL Computation parameters used to correct the image forming characteristic by the correction mechanism described later are also registered, and these conditions are set simultaneously with the settings of the fly-eye lens groups 7a to 7d. As a result, an optimal illumination condition is set for the reticle R mounted on the stage 15. The above operations can also be executed by the operator directly inputting commands and data from the keyboard 51 to the main controller MC.

Next, a mechanism for correcting the imaging characteristics of the projection optical system PL will be described. The first group lens element 20 and the second group lens element 21
Elements 25 and 27 which are correction devices for displacing
And a drive element control unit 53 for controlling the operation of these drive elements 25 and 27. The correction of the imaging characteristics of the projection optical system PL can also be performed by controlling the operation of the drive element 29 on the reticle R by the drive element control unit 53.
The drive element control unit 53, based on an instruction from the main controller MC, controls the reticle R, the first lens unit 20,
The second group lens elements 21 and 22 are independently driven by a required amount to correct the imaging characteristics of the projection optical system PL. The imaging characteristics of the projection optical system PL include a focal position, a projection magnification, distortion, curvature of field, astigmatism, and the like, and these values can be individually corrected. In this embodiment, the focus position, projection magnification, distortion, and the like in the bilateral telecentric projection optical system PL are particularly controlled by the movement of the lens elements 20, 21, and 22.
And correct the field curvature. The movement of the reticle R (consequently, the movement of the entire projection optical system PL with respect to the reticle R) corrects, for example, barrel or pincushion distortion.

The first lens element 20 closest to the reticle R is fixed to a support member 24, and the next second lens elements 21 and 22 are fixed to a support member 26. The lens element disposed below the third group lens element 23 is fixed to the lens barrel 28 of the projection optical system PL. In the following description, the “optical axis AX of the projection optical system PL” indicates the optical axis of the lens element fixed to the lens barrel 28.

The support member 24 is supported on a support member 26 by a plurality of expandable and contractible drive elements 25 (only two are shown in the figure for simplicity). The support member 26 is connected to the optical axis AX of the projection optical system PL. It is supported on the lens barrel 28 by a plurality of drive elements 27 that can expand and contract in the direction. Drive element 25, 2
Although an electrostrictive element called a piezo element is used as 7, for example, a magnetostrictive element can be used instead. The drive element control unit 53 applies necessary voltages to the drive elements 25 and 27 by servo control, and controls the first lens element 20 and the second lens elements 21 and 22 based on calculation parameters received from the main control device MC. To a different position. The reticle stage device R
An electrostrictive element is also used as the drive element 29 provided in S, and the drive element control unit 53 applies a necessary voltage to the drive elements 25 and 27 by servo driving, and receives the reticle R from the main controller MC. Move to the required position based on the calculated parameters.

The drive element control unit 53 communicates with the main controller MC and performs necessary arithmetic processing. The lower processor 53a actually drives the respective drive elements 25, 27 and 29. Is provided. The upper processor 53a determines the target position that is the optimum position for each of the first lens element 20, the second lens elements 21, 22 and the reticle R based on the calculation parameters for correcting the image characteristic received from the main controller MC. Calculate the value. The lower processor 53b calculates the driving amounts of the driving elements 25, 27, and 29 based on the target values received from the upper processor 53a via the shared memory (SHM), and based on the driving amounts, the driving elements 25 and 27. ,
Adjust the amount of expansion and contraction of 29. The upper processor 53a
Updates the target value stored in the shared memory (SHM) every 10 milliseconds.

FIG. 3 is a diagram for explaining the detection of the position of the first lens unit 20 as an example. The first group lens element 20 is driven by the drive element 25 to be displaced vertically (in the optical axis AX direction of the projection optical system PL) with respect to the second group lens elements 21 and 22. A capacitive displacement sensor 25a is attached to an upper lower surface of a column member 26a extending upward from the support member 26 of the second group lens elements 21 and 22 so as to face an upper surface of the support member 24. By monitoring the detection output of the capacitive displacement sensor 25a, the displacement of the first lens element 20 with respect to the second lens elements 21 and 22 can be determined. The amount of displacement with respect to the second group lens elements 21 and 22 and the projection optical system PL can be determined in the same manner as described above.

The voltages applied to the driving elements 25, 27 and 29 and the driving elements 25, 27 and 29 generated in response
If the relationship between the first lens element 20 and the second lens element 20 can be determined without using the displacement sensor 25a,
The group lens elements 21 and 22 and the reticle R can be displaced to desired positions. However, the driving element 2
In consideration of the hysteresis of 5, 27, and 29, the first group lens element is preferably provided with a position detector such as a differential transformer in each of the drive elements 25, 27, and 29 in addition to the above-described capacitive displacement sensor 25a. 20 can be driven to expand and contract with high precision.

[2. Illumination Method] Here, an illumination method employed in the exposure apparatus shown in FIG. 1 will be described. In this illumination method, the illumination light IL passing through a pupil plane of the illumination optical system or a conjugate plane thereof or a plane in the vicinity thereof is transmitted to the illumination optical system I.
By defining at least two local regions having centers at positions eccentric from the optical axis AX of S by a predetermined amount,
The plurality of illumination lights IL applied to the reticle R are shifted in a predetermined direction by an angle corresponding to the degree of fineness of the reticle pattern to the optical axis AX.
(Hereinafter, such an illumination method is called an inclined illumination method). For example, the fly-eye lens groups 7b, 7c, 7d shown in FIG. 2 correspond to this oblique illumination method. The fly-eye lens group 7b is
This corresponds to a normal illumination method that is symmetric and uniform around the optical axis AX of the illumination optical system IS.

Since the fineness (line width, pitch) and directionality of the reticle pattern used in the exposure apparatus are not limited to one type, the illumination optical system IS of the exposure apparatus used in the present embodiment is not limited to one type. It is desirable that the center position of the local area through which the illumination light IL passes on the pupil plane is variable according to the type of the pattern. In other words, this is because the optimum value of the direction and angle of incidence of the illumination light IL on the reticle R is determined by the direction, width, and pitch of the reticle pattern. Further, in each of the plurality of fly-eye lens groups 7a to 7d shown in FIG. 2, the area of the exit end is determined by the numerical aperture of the illumination light IL transmitted through each of the fly-eye lens groups 7a to 7d with respect to the reticle R and the projection optics. The ratio of the system PL to the reticle-side numerical aperture NA _R , the so-called σ value, is 0.1 to 0.3.
It is desirable to set so that it is about. The configuration for changing the illumination conditions, that is, for changing the light quantity distribution on the pupil plane of the illumination optical system IS is described in FIG.
The shape of the aperture of the variable aperture stop 8 shown in FIG. 1 is not limited to f. Furthermore, σ
In order to change the value, for example, the condenser optical system 6 in FIG. 1 may be a zoom lens system.

Next, the projection optical system P under each illumination condition
The light amount distribution near the pupil plane of L will be described. Here, when the pattern is formed substantially uniformly on the reticle R over the entire exposure field of the projection optical system PL, among the plurality of lens elements constituting the projection optical system PL, near the reticle R or the wafer W With this lens element, the illumination light passes almost uniformly over the entire surface regardless of the illumination conditions. On the other hand, near the pupil plane Ep of the projection optical system PL, the illuminance distribution differs for each illumination condition. For this reason, the temperature distribution generated in the lens element near the pupil plane Ep also differs for each illumination condition.
Especially in the vicinity of the pupil plane, the illumination light IL passes through in a concentrated manner.
It can be said that the illuminance (temperature) distribution differs depending on the illumination condition, and that the influence on the imaging characteristics is large. When pattern exposure is actually performed, the optimum illumination conditions corresponding to the type of the reticle (for example, a normal reticle or a phase shift reticle), the pattern line width, the shape, the periodicity, and the like, that is, the σ value and The reticle-side and wafer-side numerical apertures NA _R and NA _W of the projection optical system PL are set by driving the turret plate 7 f and the variable aperture stops 8 and 32.

[3. Method of Correcting Imaging Characteristics] Here, the first
The driving amount of the group lens element 20 is x ₁ , the driving amount of the second group lens elements 21 and 22 is x ₂ , and the focus detection system 3
Assuming that the electrical or optical offset amount (corresponding to the movement amount of the wafer W with respect to the projection optical system PL) given to 0 and 31 is x ₃ and the driving amount of the reticle R is x ₄ , the projection magnification M and the image Variations ΔM, Δ of surface curvature C and focal position F
Each of C and ΔF is represented by the following equation. ΔM = CM1 × x ₁ + CM2 × x ₂ (1) ΔC = CC1 × x ₁ + CC2 × x ₂ (2) ΔD = CD4 × x ₄ (3) ΔF = CF1 × x ₁ + CF2 × x ₂ + x ₃ + CF4 × x ₄ (4) where CM1, CM2, CC1, CC2, CF1, C
F2 is the variation .DELTA.M, a constant representing [Delta] C, [Delta] D, the change rate relative to the drive quantity x _1, x ₂ of the [Delta] F, CD4, C
F4 is a constant representing the rate of change with respect to the drive amount x ₄ of the reticle R of the amount of change [Delta] D, [Delta] F.

From the above, equations (1), (2),
(3), (4) by setting the drive amount x ₁ ~x ₄ in the variation .DELTA.M, [Delta] C, [Delta] D, it is possible to arbitrarily correct the [Delta] F. Here, the case of simultaneously correcting the four types of imaging characteristics has been described. However, if the amount of change in the imaging characteristics due to the absorption of illumination light among the imaging characteristics of the projection optical system is negligible, When the above-described correction is not required, and when the imaging characteristics other than the four types described in the present embodiment are significantly changed, it is necessary to correct the imaging characteristics. Further, when the change amount of the field curvature is corrected to be equal to or less than the allowable value, the change amount of the astigmatism is also corrected to be equal to or less than the allowable value. Therefore, in this embodiment, the correction of the astigmatism is not particularly performed. Shall be.

In this embodiment, two movable lens elements are provided. However, three or more movable lens elements may be provided. In this case, various shape distortions (distortion such as trapezoidal or rhombic) and image plane It is possible to cope with curvature (astigmatism). By employing such an imaging characteristic correction mechanism, it becomes possible to more sufficiently cope with a change in the imaging characteristic of the projection optical system PL due to absorption of the illumination light IL.

[4. Time-Dependent Change of Imaging Characteristics] Next, a method of calculating the time-dependent changes in the image forming characteristics of the projection optical system PL will be described. By estimating the amount of change with time, the imaging characteristics can be corrected. In the present embodiment, the imaging characteristics such as the projection magnification, the curvature of field, the distortion, and the focal position have been described. Here, the projection magnification will be described as an example. In the present embodiment,
The case where the σ value of the illumination optical system IS is changed as the illumination condition will be described.

The change amount ΔM of the projection magnification of the projection optical system PL
Is expressed as a first-order lag system as a saturation characteristic ΔM ₀ (1-exp (t / τ)) from a balance between the amount of heat absorbed by the projection optical system PL and the amount of heat emitted from the projection optical system PL. . Here, ΔM ₀ represents a final change amount of the projection magnification, τ represents a time constant, and t represents a time from the start of irradiation. Here, assuming that the irradiation energy to the projection optical system PL is E, the ratio ΔM ₀ / E and the time constant τ are values specific to the projection optical system PL, so that the change amount ΔM of the magnification is the ratio ΔM ₀ / It can be determined by E and the time constant τ. However,
Since the structure of the projection optical system PL is complicated, it may not be strictly the simple saturation characteristic as described above, but may be expressed as the sum of several first-order delay systems. For simplicity, a case in which a simple change characteristic is shown will be described.

In FIG. 1, when the reticle R is replaced, the stage 17 is driven to move the photoelectric sensor 33 to the position of the optical axis AX of the projection optical system PL, and the amount of illumination light IL incident on the projection optical system PL is measured. Next, main controller MC actually measures the projection magnification while irradiating projection optical system PL with illumination light IL, and determines the ratio ΔM /
E, the change amount of the projection magnification is sequentially calculated based on the time constant τ, the irradiation energy detected by the photoelectric sensor 33, and the opening / closing time of the shutter 3.

Here, when the σ value of the illumination optical system changes as described above, the light amount distribution of the illumination light IL in the lens element near the pupil plane Ep of the projection optical system PL changes. For example, when the σ value is small, it is considered that the irradiation energy is concentrated at the center of the pupil and the temperature at the center increases, and the lens element undergoes large thermal deformation near the center. For this reason,
Even when the total irradiation energy amount is the same, it is considered that the ratio ΔM / E becomes larger when the σ value is smaller. On the other hand, when the σ value is small, it is considered that when the irradiation of the illumination light IL is interrupted, the temperature of the lens element falls relatively sharply. Therefore, when the σ value is small, the time constant τ
Is considered to be smaller. From the above, it can be seen that the ratio ΔM / E and the time constant τ both change with the change of the σ value.

In the above description, the case where the σ value is changed has been taken as an example. However, other lighting conditions (such as annular illumination, multiple tilt illumination, etc.) can be considered in the same manner. Also, when a phase shift reticle is used, the angle at which the diffracted light from the reticle pattern enters the projection optical system is different from that of a normal reticle, so that it can be considered that the imaging characteristics similarly change.

In the case of the present embodiment, the change of the imaging characteristic is compensated by the driving elements 25, 27, 29 and the driving element control section 53 which are the imaging characteristic correcting mechanism. At this time, among the items to be corrected (focal position, projection magnification, various aberrations, etc.),
A simple or efficient correction is performed by selecting one or two or so from among those having a large effect on the image forming pattern (projected image of the reticle pattern) (for example, a magnification change amount ΔM).

[5. Prohibition of Exposure Operation, etc.] Next, a criterion for prohibiting the exposure operation according to the heat accumulation amount accumulated in the projection optical system PL with the incidence of the illumination light will be described.

In the present embodiment, regardless of whether or not the above-described processing for correcting the image forming characteristic is performed, attention is paid to the image forming characteristic which is most problematic in practical use when the exposure apparatus is used continuously. I do. Here, for example, coma aberration is considered as the image forming characteristic. The change characteristic of the coma aberration corresponding to the heat accumulation amount of the projection optical system PL due to the absorption of the illumination light is expressed as a first-order lag system or the sum of the first-order lag systems, similarly to the above-described projection magnification. . Therefore, the model of the change characteristic of the coma aberration obtained in advance by experiment or simulation is
If stored in the main controller MC (memory (not shown)), the heat accumulation amount of the projection optical system is sequentially calculated,
The amount of change in coma due to this heat accumulation amount can be obtained. This makes it possible to determine whether or not the exposure operation should be interrupted by comparing the calculated value with the permissible limit value of the coma aberration (variation amount).

[0052] for example, the change amount ΔG coma at a certain time exceeds the guard value GL _2, If you continue this state exposure operation, the amount of change ΔG is assumed to have it Ciao exceeds the limit value GL _1. In this case, before starting the exposure operation on the next wafer W, the change amount ΔG is compared with the caution value GL _2, and based on the comparison result, the exposure operation is interrupted and the change amount ΔG
There continue to stop the exposure operation until the warning value GL ₂ below. Then, the amount of change ΔG is by resuming the exposure operation at the time when a warning value GL _2, constantly change amount ΔG is maintained below a limit value GL _1, i.e. deterioration of the imaging pattern by coma predetermined Exposure is performed in a state where it is kept within the allowable range.

According to the above method, the number of processed wafers per unit time is reduced due to the stop time, and the productivity (throughput) of the apparatus may be reduced. However, the occurrence of defective products due to the deterioration of the imaging characteristics is reduced. It is possible to prevent a decrease in yield. Here, the description has been given by taking the coma aberration as an example, but the types and number of imaging characteristics to which the above method is applied,
The allowable limit value of the change amount and the like may be determined in consideration of the magnitude of the influence on the imaging pattern, the throughput, the yield, and the like.

Here, when the illumination condition changes, the change amount and the change characteristic (time constant) of the imaging characteristic (particularly, aberration) also change. Therefore, an imaging characteristic which is a criterion for determining whether or not the exposure operation should be interrupted so as to suppress the change amount to be equal to or less than the allowable limit value, that is, the “imaging characteristic that is most problematic in practical use” may be different for each illumination condition.

As described above, when the illumination condition is changed, the imaging characteristic for which the amount of change needs to be sequentially calculated under the changed illumination condition in advance as "the imaging characteristic which is most problematic in practical use" is required. During the exposure operation, the amount of change is sequentially calculated only for the selected image forming characteristic, and is compared with an allowable limit value. Also, when the imaging characteristics selected as described above are those in which the amount of change is corrected by, for example, the imaging characteristic correction mechanism (the driving elements 25, 27, and 29 and the driving element control unit 53 in FIG. 1). It is not necessary to newly calculate the amount of change by performing another calculation, and the amount of change calculated for use in the correction mechanism may be directly used for comparison with the allowable limit value.

In the above description, sufficient time has elapsed after the change of the illumination condition, and the influence of the illumination condition before the change has already disappeared (that is, the heat accumulation amount remaining in the projection optical system as a history is almost zero). It is assumed that the exposure operation is started in this state. However, since the history before the change of the illumination condition remains in the projection optical system PL, strictly speaking, the change amount of the imaging characteristic is simply calculated by comparing the change amount under the two conditions before and after the change of the illumination condition. Cannot be expressed as a sum.

Then, after the shutter is closed to stop the exposure operation for changing the illumination condition, a predetermined time until the influence (history) of the illumination condition before the change becomes sufficiently small, for example, the change amount Δ of the imaging characteristic. Until the value decreases to a certain level M _S , the exposure operation is stopped.
_{At S} , the shutter is opened and the exposure operation is started under the changed lighting conditions. According to this method, it is possible to eliminate the history of the lighting conditions before the change as described above,
By simply switching the allowable limit value of the change amount of the imaging characteristic to a value most suitable for the changed illumination condition, the change amount of the imaging characteristic can be suppressed within a predetermined allowable range.

On the other hand, when the exposure operation is not stopped when the illumination condition is changed and the exposure is started immediately after the change, for example, for each combination of the illumination conditions, the amount of heat accumulated in the projection optical system PL before and after the illumination condition is changed. (Corresponds to irradiation energy)
In consideration of the exposure stop time at the time of changing the illumination condition, etc., it is possible to strictly obtain the allowable limit value corresponding to the change amount of the imaging characteristic in the transient state at the time of changing the illumination condition by an experiment or simulation in advance. Good.

[6. Above, etc., the operation of the imaging characteristic correcting mechanism is stopped] The correction of the imaging characteristic of the projection optical system PL caused by the irradiation of the illumination light IL has been described. However, the projection optical system P
The heat storage phenomenon in L is not caused only by the illumination light IL, but strictly, it is necessary to consider the influence of the projection optical system PL and a heating element incorporated in the periphery thereof. In particular, the demand for higher accuracy is increasing, and the heat generation from the driving elements 25, 27, and 29 themselves, which are the imaging characteristic correction mechanisms, is becoming non-negligible. In consideration of the heat generated from the driving elements 25, 27, and 29 themselves, during the exposure processing, the driving elements 2
5, 27 and 29 are servo-driven to drive lens element 2
0, 21, 22 and reticle R are displaced to target positions,
During the non-exposure processing, the lens elements 20, 21, and 22 are displaced to a reference position (initialization position), and then the servo driving of the driving elements 25, 27, and 29 is stopped to stop the lens elements 20, 21, and 22 and the reticle R. May be fixed at the reference position. This makes it possible to reduce the amount of heat generated from the driving elements 25, 27, and 29 during the non-exposure processing, and prevent such heat generation from affecting the imaging characteristics of the projection optical system R.

Here, “during exposure processing” means that the illumination light IL
In addition to the exposure operation (shot exposure) in which the wafer W and the reticle W are relative to the projection optical system PL to perform alignment by detecting the relative displacement of the wafer W and the reticle W with respect to the projection optical system PL. On the other hand, “during non-exposure processing” excludes the above case, and means the time of loading the wafer W or the reticle R, the maintenance of the exposure apparatus, the time of calibration, and the like.

The reference position of the lens element 20 and the like during the non-exposure processing is set so as to show an optimum image forming characteristic in a standard use condition. The drive element control device 53 calculates based on the data received from the main control device MC. As described above, if the lens elements 20, 21, 22 and the reticle R are moved to the reference position and fixed during the non-exposure processing, the driving elements 25, 2
7 and 29 are servo-driven to drive the lens elements 20 and 2
The time when the reticle R is displaced to the target position is reduced.

In the above description, during the non-exposure processing,
Although the servo drive of the drive element 25 and the like is stopped to fix the lens element 20 and the like at the initialization position, the position for fixing the lens element 20 and the like is set at these initialization positions (usually fixed and the exposure apparatus The setting does not change except during installation or maintenance). For example, if the next exposure is to be performed under the same illumination conditions as the previous exposure, during the non-exposure process during that time, the target position (fixed value) of the lens element 20 or the like immediately after the start of the previous exposure or the previous exposure It is also conceivable to arrange a lens element or a reticle at those target positions (fixed values) immediately before the end of exposure.

In the above description, the driving element 2 is not operated during the non-exposure processing.
The servo drive of 5, 27, and 29 was stopped.
In some cases, the amount of heat generated by the servo drive of the drive elements 25, 27, and 29 does not significantly affect the imaging characteristics of the projection optical system PL. For example, when the irradiation energy of the illumination light incident on the projection optical system PL under a specific illumination condition is relatively large, or when there is no laser measuring device for position detection or the like in the surroundings, the driving elements 25, 27, and 29 are servo-driven. The heat value is less than the allowable heat value in the operation of the exposure apparatus and can be ignored. In such a case, the drive elements 25, 27, and 29 are servo-driven even during non-exposure processing. in this case,
The characteristics of the projection optical system PL can be stabilized because the imaging state of the projection optical system PL is not suddenly changed between the exposure processing and the non-exposure processing. In addition, even if the amount of heat generated is less than the allowable amount of heat generated during the operation of the exposure apparatus, the change in the amount of heat generated may exceed the allowable amount of change in the operation of the exposure apparatus. In any case, if the driving elements 25, 27, and 29 are continuously servo-driven, the operation of the exposure apparatus can be stabilized.

More specifically, during the non-exposure processing, the driving element 25,
A first operation mode in which the servo drives 27 and 29 are stopped;
The second operation mode for maintaining the servo drive of the drive elements 25, 27, and 29 even during the non-exposure processing can be appropriately selected. Which of the first and second operation modes is selected is based on the following criteria. That is, the driving elements 25, 27, 29 during the non-exposure processing
In the case where the amount of heat generated from the driving elements 25, 27, and 29 during the non-exposure processing is large, the amount of heat generated from the drive elements 25, 27, and 29 during non-exposure processing is large. When the influence on the imaging characteristics of the projection optical system PL is negligible and the amount of heat generated by the servo drive is less than the allowable heat generation in the operation of the exposure apparatus, the allowable heat generation in the operation of the exposure apparatus Even in the following cases, the variation in the heat generation amount may exceed the allowable variation amount in the operation of the exposure apparatus, and the second operation mode is selected.

During the non-exposure processing, the driving elements 25, 2
When stopping the servo drive of 7, 29, instead of this,
The response can also be delayed by increasing the time interval for updating the target position during servo driving of the drive elements 25, 27, 29. In this case, the period of change of the voltage applied to the driving elements 25, 27, and 29 becomes longer, and the amount of generated heat also decreases. However, since the displacement of the driving elements 25, 27, and 29 is slow, the lens elements 20, 21, and 22 and the reticle R may not be able to be moved while accurately following the change in the target position. Immediately before the start, the response of the drive elements 25, 27, and 29 is made faster, so that the lens element 20 and the like can be quickly moved to the target position.

When the exposure shot and the alignment are substantially continuous, it is determined that the exposure shot and the drive elements 25, 27, and 29 are being integrated, and the servo driving of the drive elements 25, 27, and 29 is continued. When another process or the like is interposed between the exposure shot and the alignment, the driving elements 25, 27, 29
Temporarily suspends servo drive.

[7. Outline of Operation of Exposure Apparatus] Next, an example of processing inside the main controller MC will be described with reference to a flowchart shown in FIG.

Here, an example will be described in which the illumination conditions are not changed for the same reticle R and the reticle is not changed while the same wafer is being exposed.

First, in step S 101, main controller MC checks whether a reticle is mounted on reticle holder 14 or not.
If the reticle R is not placed on the reticle holder 14 based on the input information from 1 or a program or the like input in advance, the reticle is immediately loaded, and if the reticle R is placed, It is determined whether or not another reticle R is loaded on the reticle holder 14. Here, it is assumed that the reticle is to be replaced, and the process proceeds to the next step S102.

In step S102, main controller M
C is the state of the exposure apparatus, that is, the illumination condition is normal illumination,
It is checked which of the plurality of oblique illuminations or the like is set, the σ value of the illumination optical system, the numerical aperture of the projection optical system PL, the aperture shape / position of the variable field stop 10, and the like. This is performed by recognizing the setting state of the drive system 54, the variable aperture stops 8, 32, the variable field stop 10, and the like.

In the next step S103, the barcode BC of the reticle R to be newly loaded on the reticle holder 14 is read. Then, main controller MC reads an operation parameter corresponding to the barcode BC (name of reticle) from the memory. As a result, the illumination conditions most suitable for the type of the reticle (normal reticle, phase shift reticle) and the fineness and periodicity of the pattern, that is, whether to use the normal illumination or the multi-tilt illumination, In the illumination, conditions such as the number of fly-eye lens groups and their positions, the σ value of the illumination optical system IS, the numerical aperture of the projection optical system PL, and the aperture shape and position of the variable aperture stop 10 are recognized.

In the next step S104, main controller M
C drives the holding member 7, the variable aperture stops 8, 32, the variable aperture stop 10, and the like based on the illumination conditions read in step S103, and sets the optimal illumination conditions for the reticle R and its pattern. In this step S104, it is sufficient to change only the lighting condition different from the lighting condition confirmed in the previous step S102, and if there is no need to change the lighting condition, the process immediately proceeds to step S105.

Here, when the illumination conditions are changed as described above, for example, when the normal illumination (the fly-eye lens group 7a) is changed to the multiple tilt illumination (the fly-eye lens group 7d), the projection optical system PL emits the illumination light. The passing area of the IL is completely different before and after the illumination condition is changed. For this reason, the method of calculating the target value when correcting the imaging characteristics of the projection optical system PL is changed. That is, the projection optical system P under the changed illumination condition
The driving element 25, which is an imaging characteristic correction mechanism, is configured such that the projection magnification of L and various aberrations (distortion, curvature of field, astigmatism, coma, spherical aberration, etc.) fall within a newly set allowable range. 27, 29 and the operation of the drive element control device 53 are controlled.

In the next step S105, main controller M
C determines the type of the reticle R and the imaging characteristics to be focused on under the illumination conditions, that is, “the imaging characteristics that are most problematic in practical use”. Further, as described above, when the imaging characteristic (hereinafter, referred to as the focused imaging characteristic) to be set for which the allowable limit value of the variation is set is determined, the focused imaging under the new illumination condition is determined. The change amount of the characteristic and the change characteristic are also read out from the memory, and the calculation unit is set so that the change amount of the characteristic can be sequentially calculated (step S105).

In the next step S107, the pattern information (line width, density distribution in the pattern plane, etc.) of the reticle R to be exposed is also read from the memory, and the allowable limit of the previously set change amount of the focused imaging characteristic is set. Determine the value (Step S1
06). Thus, the setting of various conditions in main controller MC is completed.

In the next step S108, main controller M
It is determined whether C has changed the lighting conditions (step S)
107). Here, it is assumed that the illumination condition read from the memory under the new reticle R is different from the condition confirmed in the previous step S102 and that the illumination condition has been changed, and the process proceeds to the next step S108. If it is determined in step S107 that the illumination condition has not been changed, the process immediately proceeds to step S110.

[0077] At step S108, whether the history of the lighting conditions before the change remains in the projection optical system PL, ie, whether the amount of change in imaging characteristic of the projection optical system PL by the history is less than or equal to the level M _S Determine whether or not. Here, the exposure operation has been stopped due to the change in the illumination condition, and the change amount has gradually decreased accordingly.However, the attenuation calculation of the change amount of the imaging characteristic is performed by using the calculation parameter under the illumination condition before the change. (Time constant and the like) and are continuously performed from the stop of the exposure operation. Therefore, main controller MC compares the calculated value of the change amount with level M _S. If the calculated value is equal to or less than level M _S , no history remains in projection optical system PL, that is, after the change, It is determined that the amount of change in the imaging characteristics can be sequentially calculated using the calculation parameters under the illumination conditions, and the process proceeds to the next step S110.

On the other hand, if it is determined that the history remains in the projection optical system PL, the flow advances to step S109, and after waiting for a predetermined time, returns to step S108 to reduce the change amount of the imaging characteristic to the level M _S or less. It is determined whether or not. If it is determined that the history remains, the process proceeds to step S109 again, and thereafter, steps S108 and S109 are performed.
Is repeatedly executed, and the process proceeds to step S110 when the calculated value of the change amount of the imaging characteristic becomes equal to or less than the level M _S.

In the next step S110, main controller M
It is determined whether or not C is equal to or less than the allowable limit value of the focused imaging characteristic. This determination is made in exactly the same way as in step S108 by comparing the sequentially calculated change amount with the permissible limit value. If the change amount (calculated value) is equal to or smaller than the permissible limit value, the step is immediately performed. 112
The exposure process for the wafer W is started. on the other hand,
If the amount of change exceeds the allowable limit, step S1
Then, after waiting for a certain time (for example, about 1 second), the process returns to step S110 again to determine whether the amount of change is equal to or less than the allowable limit value.

Thereafter, steps S110 and S111 are repeatedly executed, and when the amount of change becomes equal to or less than the allowable limit value, the process proceeds to step S112.

In step S112, alignment is performed, and the pattern of the reticle R is sequentially exposed on the wafer W under new illumination conditions. After completion of the exposure processing, main controller MC determines whether or not to perform exposure on the next wafer W (step S113). Here, since the exposure of the first wafer W has only been completed, the next step S11
Proceed to 4 to execute wafer exchange.

Further, the main controller MC is provided with the following (second sheet).
It is determined whether or not to perform reticle exchange for wafer W (step S102). Here, it is assumed that the pattern of the same reticle R is exposed, and the process proceeds to step S110.

In step S110, the change amount of the focused imaging characteristic is compared with the permissible limit value in the same manner as described above. If the change amount is equal to or smaller than the permissible limit value, the flow advances to step S112 to proceed to step S112. Start exposure to.

Hereinafter, the above sequence is repeatedly executed until the exposure for all the wafers to be exposed is completed. As a result, it is possible to always perform pattern exposure on a wafer under highly accurate imaging characteristics. When the reticle is replaced, steps S102 to S106 are executed again, and when the illumination condition is changed, steps S108 and S109 may be executed.
Further, if the illumination condition is not changed even when the reticle is replaced, it is not necessary to execute steps S105 and S106.

[8. Specific operation example of the imaging characteristic correction mechanism)
FIG. 5 is a diagram illustrating the operation of the drive element control unit 53, which is an imaging characteristic correction mechanism. In this case, the driving elements 25, 2
7, 29 are operated in an operation mode in consideration of heat generation from themselves.

First, a start-up process of the imaging characteristic correcting mechanism is performed (step S200). Specifically, when the power of the exposure apparatus is turned on, the driving element control unit 5 and the main control unit MC
3 rises. The upper processor 53a of the driving element controller 53 sends the driving element 25 to the lower processor 53b.
Request initial operations 27 and 29. The lower processor 53b first self-diagnoses the hardware environment in response to the request. As a result of the self-diagnosis, when it is determined that there is no problem, the maximum voltage is applied to the piezo elements which are the driving elements 25, 27 and 29, and the positions of the reticle R and the lens elements 20, 21 and 22 at that time (the maximum extension). Position) is detected by the capacitive displacement sensor 25a. Next, the driving elements 25, 27,
A zero voltage is applied to the piezo element 29, and the position (the most contracted position) of the reticle or lens element at that time is detected by the capacitive displacement sensor 25a or the like. Next, the difference between the most extended position and the most contracted position is calculated to determine the stroke of each of the driving elements 25, 27, and 29. If the stroke obtained in this way does not reach the reference value, it is determined that the drive elements 25, 27, and 29 have failed, and the subsequent processing is stopped. Issues a warning.

Next, the host processor 53a passes a signal to and from the main controller MC to determine whether or not the exposure processing is being performed (step S201). If it is determined in step S201 that the exposure process is being performed, the upper processor 53a calculates the target position of the lens element 21 and the like based on the calculation parameters received from the main controller MC in step S202, and the lower processor 53b is driven in step S203. The elements 25, 27, and 29 are servo-driven to displace at least one of the lens elements 20, 21, and 22 and the reticle R to a target position. Next, in step S204, it is determined whether or not the exposure processing has been completed. If the exposure processing has not been completed, the process returns to step S202. Step S204
If it is determined that the exposure processing has been completed, the process proceeds to step S205. On the other hand, if it is determined in step S201 that the non-exposure process is being performed, a reference position of the lens element 21 and the like is calculated based on the calculation parameters received from the main controller MC in step S212.
After the lens element 21 and the like are moved to the reference position, the servo driving of the drive elements 25, 27, and 29 is stopped to lock the lens elements 20, 21, 22 and the reticle R at the reference position. Next, the process proceeds to step S205, in which a signal is transferred to and from the main control device MC, and the drive elements 25, 2
It is determined whether or not the operations 7 and 29 (servo drive and lock) are to be maintained. If it is determined in step S205 that the operations are not stopped, the process returns to step S201. If it is determined in step S201 that non-exposure processing is being performed, steps S201, S212, S213, and S described above are performed.
The operation of 205 is repeated. If it is determined in step S205 that servo drive or locking of the driving elements 25, 27, and 29 is not required, such as by stopping all operations of the exposure apparatus, and it is determined that the driving is to be stopped, the processing ends.

[0088]

As is apparent from the above description, according to the exposure apparatus of the present invention, during the exposure processing, the control device servo-drives the correction device to move the predetermined optical element to the predetermined target position. During the non-exposure process, the servo drive of the correction device is stopped, so that the amount of heat generated from the correction device during the non-exposure process is reduced, and the generated heat causes the imaging characteristics of the projection optical system and the projection optical system Can be prevented from affecting the accuracy and the like of the measuring device around the device.

According to another aspect of the exposure apparatus,
A first operation mode in which a control device servo-drives the correction device during an exposure process to displace the predetermined optical element to a predetermined target position and stops servo driving of the correction device during a non-exposure process; During the exposure process and the non-exposure process, the correction device is servo-driven to selectively switch the second operation mode in which the predetermined optical element is displaced to a predetermined target position. If the amount of heat generated from the correction device is large and the effect on the imaging characteristics of the projection optical system cannot be ignored, the correction device is operated in the first operation mode, and the amount of heat generated from the correction device during non-exposure processing is not large. When the influence on the imaging characteristics of the projection optical system is negligible, the correction device can be operated in the second operation mode.

Further, according to a preferred aspect of the present invention, the control device holds the predetermined optical element at a predetermined reference position when the servo drive of the correction device is stopped. If the lighting conditions of
Next, the time when the correction device is servo-driven to displace the predetermined optical element to a predetermined target position is reduced.

Further, according to a preferred aspect of the present invention, the first operation mode is selected when there is a possibility that the heating value when the control device servo-drives the correction device may exceed a predetermined allowable heating value. Therefore, the imaging characteristics of the imaging optical system can be maintained at a constant level.

According to a preferred aspect of the present invention, the second operation mode is selected when there is a possibility that the amount of heat generation when the control device servo-drives the correction device may exceed a predetermined allowable fluctuation amount. Therefore, the imaging characteristics and the like of the imaging optical system can be stabilized.

According to a preferred aspect of the present invention, when the control device changes the illumination condition of the illumination optical system, it determines whether to switch the first and second operation modes. An exposure apparatus capable of maintaining necessary imaging characteristics and the like in accordance with changes in illumination conditions caused by the exposure can be provided.

Further, according to the exposure method of the present invention, during the exposure processing, the predetermined optical element constituting the imaging optical system is displaced to the target position to correct the imaging characteristic, and during the non-exposure processing, Since the displacement of the predetermined optical element is stopped, the amount of heat generated due to the correction of the imaging characteristics during the non-exposure processing is reduced, and the heat generation is prevented from affecting the imaging characteristics of the projection optical system. be able to.

According to the exposure method according to another aspect,
A first operation mode in which a predetermined optical element constituting the imaging optical system is displaced to a target position during an exposure process to correct an imaging characteristic and stop the displacement of the predetermined optical element during a non-exposure process; During the exposure processing and the non-exposure processing, the predetermined optical element is displaced to the target position and the second operation mode for correcting the imaging characteristic is selectively switched and executed. When the amount of heat generated due to the correction of the image characteristics is so large that the influence on the image forming characteristics of the projection optical system cannot be ignored, the correction device is operated in the first operation mode, and the image forming characteristics during the non-exposure processing are reduced. In a case where the amount of heat generated by the correction is not large and the influence on the imaging characteristics of the projection optical system can be ignored, the correction device can be operated in the second operation mode.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a configuration of an exchange mechanism including a plurality of fly-eye lens groups.

FIG. 3 is a diagram illustrating a mechanism for driving a lens element of a projection optical system.

FIG. 4 is a flowchart illustrating an example of a control operation of an imaging characteristic of a projection optical system.

FIG. 5 is a flowchart illustrating an example of an operation of controlling the imaging characteristics of the projection optical system.

[Explanation of symbols]

 Reference Signs List 20 first-group lens element 21, 22 second-group lens element 25, 27, 29 drive element 33 irradiation amount monitor 53 drive element control unit IS illumination optical system MC main controller OS light source device R reticle RS reticle stage device PL projection Optical system W Wafer WS Wafer stage device

Claims (8)

[Claims] An illumination optical system for irradiating a mask pattern with illumination light from a light source, an imaging optical system for forming and projecting an image of the mask pattern on a photosensitive substrate, and a predetermined optical system constituting the imaging optical system A correction device for correcting an imaging characteristic by displacing an optical element, wherein during the exposure process, the correction device is servo-driven to displace the predetermined optical element to a predetermined target position, An exposure apparatus, comprising: a control device for stopping servo driving of the correction device during non-exposure processing. 2. An illumination optical system for irradiating illumination light from a light source onto a mask pattern, an imaging optical system for imaging and projecting an image of the mask pattern on a photosensitive substrate, and a predetermined optical system constituting the imaging optical system. A correction device for displacing an optical element to correct an imaging characteristic, the servo device driving the correction device during exposure processing to displace the predetermined optical element to a predetermined target position, and A first operation mode in which a servo drive of the correction device is stopped during the exposure process, and a servo drive of the correction device during the exposure process and the non-exposure process to displace the predetermined optical element to a predetermined target position. An exposure apparatus comprising: a control device that selectively switches between a second operation mode and a second operation mode. 3. The control device according to claim 1, wherein when the servo drive of the correction device is stopped, the control device holds the predetermined optical element at a predetermined reference position.
The exposure apparatus according to any one of the above. 4. The control device according to claim 2, wherein the control device selects the first operation mode when there is a possibility that a heat generation amount when the correction device is servo-driven exceeds a predetermined allowable heat generation amount. Exposure apparatus according to the above. 5. The control device according to claim 1, wherein the control device selects the second operation mode when there is a possibility that the heat generation fluctuation amount when the correction device is servo-driven exceeds a predetermined allowable fluctuation amount. 3. The exposure apparatus according to item 2. 6. The exposure apparatus according to claim 1, wherein the control device determines whether to switch the first and second operation modes when the illumination condition of the illumination optical system is changed. 7. An exposure method for transferring an image of a mask pattern onto a photosensitive substrate via an image forming optical system while correcting the image forming characteristics of the image forming optical system. An exposure method, wherein a predetermined optical element constituting an optical system is displaced to a target position to correct an imaging characteristic, and the displacement of the predetermined optical element is stopped during non-exposure processing. 8. An exposure method for transferring an image of a mask pattern to a photosensitive substrate via an image forming optical system while correcting an image forming characteristic of the image forming optical system. A first operation mode in which a predetermined optical element constituting the system is displaced to a target position to correct the imaging characteristic and stop the displacement of the predetermined optical element during the non-exposure processing; An exposure method characterized by selectively switching and executing a second operation mode for correcting an imaging characteristic by displacing the predetermined optical element to a target position during processing.