JP3278901B2 - Exposure method and circuit pattern body manufacturing method using the exposure method, or exposure apparatus and circuit pattern body manufactured by the exposure apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus used for manufacturing semiconductor devices, liquid crystal display devices, printed circuit boards, and the like.

[0002]

2. Description of the Related Art In this type of exposure apparatus, an object to be exposed, such as a semiconductor wafer, a glass plate, or an original wiring pattern cell, is mounted on a large movable stage, and an image or shadow of a pattern to be exposed is formed. It is positioned and exposed. In a step-and-repeat type (or step-and-scan type) exposure apparatus that sequentially exposes a pattern at a plurality of positions on a wafer or a glass plate, a so-called stepper, the positioning accuracy of a substrate to be exposed is less than submicron. Orders are required, and high speed is required to increase the productivity of device manufacturing.

In general, a stepper is provided with a projection optical system for projecting a mask pattern called a reticle onto a photosensitive substrate (wafer) at a fixed magnification.
This projection optical system has an extremely high resolution and is composed only of a refraction system (lens), one composed only of a reflection system (mirror), or one composed of a combination of a refraction system and a reflection system. , There are various types. Also, the projection magnification may have various values (× 1, × 1/2, × 1 /
4, × 1/5, × 1/10, etc.).

Further, there are various field sizes which can be projected at one time. Generally, the field size in a projection optical system for a wafer stepper is about 10 mm square to 30 mm square. However, it is smaller than the wafer size (5 inches, 6 inches, 8 inches, etc.).
Therefore, in a wafer stepper or the like, the reticle pattern is exposed on the entire surface of the wafer by repeatedly moving the movable stage on which the wafer is mounted by stepping (or scanning) a fixed distance and projecting and exposing the reticle pattern. At this time, the relative alignment between one shot area (exposed area) on the wafer and the projected image of the reticle pattern by the projection optical system is confirmed by various alignment systems, and the alignment is achieved. The movable stage is positioned two-dimensionally. Normally, the coordinate position of the movable stage is measured successively by a light wave interferometer (laser interferometer), and the deviation between the target position confirmed by the alignment system and the position measured by the laser interferometer (current position) is minimized. The servo control of the stage is performed so as to be zero.

[0005]

In the conventional apparatus as described above, in order to maintain high positioning accuracy, it is necessary to move a heavy movable stage with increased rigidity at a large acceleration. However, the fact that a heavy object moves in the exposure apparatus means that unnecessary vibration (sway) or deformation occurs in the entire apparatus or a part of the apparatus. This vibration can be suppressed to a fairly small value if sufficient rigidity is obtained in the structure of the exposure apparatus. However, if the vibration is coped with, the self-weight of the apparatus becomes many times as large as the current one, and the practicality is poor. For this reason, the conventional apparatus detects that the measured value of the laser interferometer for the movable stage has stayed within a permissible range centered on the target value for a certain minute time, and converges the vibration (shake) ( Was settled).

However, considering the positions where the fixed mirror and the movable mirror of the laser interferometer are mounted, the vibrations and fluctuations are not always converged in all parts in the exposure apparatus. For this reason, even if the image of the reticle pattern is projected and exposed after the fluctuation of the measurement value of the laser interferometer is converged by the conventional method, the relative positions of the reticle and the projection optical system wafer stage during the exposure time are not changed. A slight shift has occurred in the lateral direction (or the optical axis direction). Therefore, each exposure position of a plurality of shot regions arranged on a wafer in a step-and-repeat manner has an error with respect to a design position or a position determined by an alignment result, that is, an arrangement error or a stepping error. Transfer position error occurred. As described above, when the pattern projection image and the wafer stage are slightly shifted during the exposure time, depending on the amount of the shift, the image contrast on the wafer to achieve fine image formation, or strictly speaking, the resist layer on the wafer. The cumulative contrast in the process of forming a latent image is reduced, which may have a significant effect on the resolution. Such deterioration of the resolving power can be considered in the same manner as a camera shake at the time of shutter release in a general photographic camera, an image shake at the time of photographing a fast-moving subject, and the like.

In the case where the measured values of the laser interferometer have convergence, disturbances (vibration of the floor of a factory, movement of an operator or a self-propelled robot in a factory, external devices, If the measured value deviates from the convergence range due to the operation of the exposure, the exposure may be interrupted. However, it is possible that the laser interferometer readings will not change from the convergence range if disturbances are added to the stepper and cause a general sway or movement of other structures within the stepper. .

Accordingly, the present invention makes it possible to transfer a pattern with a high resolution in a state where there is no image blurring even when the exposure apparatus is totally or locally shaken, and to use a small shift of the exposure position. An object of the present invention is to provide an exposure apparatus in which alignment errors, stepping errors, and the like are significantly reduced.

[0009]

Means for Solving the Problems Therefore, in the present invention,
When exposing a pattern of a mask (reticle) onto a photosensitive substrate, at least a portion where a vibration or a deformation in an apparatus structure occurs that deteriorates (deteriorates) a relative alignment state between the mask and the photosensitive substrate. A detection means for detecting vibration and deformation is provided at one location, and based on an output signal of the detection means, a value indicating a degree of deterioration of an alignment state and a transfer accuracy of a mask pattern exposed on a photosensitive substrate are supported. The main point is to provide arithmetic means for sequentially calculating the calculated value or the value corresponding to the transfer position error.

The exposure operation is controlled by controlling the timing (start or interruption) of the exposure operation on the basis of the value calculated by the arithmetic means, or by analyzing the temporal characteristics of vibration and deformation to perform the long-time exposure. For example, the exposure sequence is switched to be performed.

[0011]

In the present invention, the setting of the exposure waiting time is controlled by the sensor output for detecting the vibration or deformation of the portion in the apparatus which has an adverse effect on the exposure position. Unnecessary waiting operation caused by the setting is eliminated, and a decrease in throughput can be prevented.

Further, when the position shift of the shot is predicted due to the vibration caused by the disturbance during the exposure, the exposure is interrupted by closing the shutter or the like, so that an apparatus having a structure substantially resistant to the disturbance can be obtained. On the other hand, when switching to long-time exposure, even if there is vibration, the mask pattern is exposed at its average position, so that the shot arrangement accuracy as a whole is improved and the contrast of the exposed image is further improved. Also improve.

[0013]

FIG. 1 is a diagram showing a schematic configuration of an exposure apparatus (wafer stepper) to which the present invention is applied. The reticle 1 patterned with a chromium layer or the like is placed on a reticle stage that moves two-dimensionally by about several mm on the reticle-side column 1A. The pattern of the reticle 1 is image-formed and projected on the wafer 3 by the projection lens 2. The projection lens 2 is fixed to the lens-side column 2A via a flange, and the distance between the reticle 1 and the projection lens 2 and the distance between the projection lens 2 and the wafer 3 are set to constant dimensions by the columns 1A and 2A.

Illumination of the reticle 1 is performed by an illumination system 4, and light from a light source (such as a mercury lamp) in the lamp house 4A is made uniform by various optical components (such as a fly-eye lens) in the illumination system 4. The illumination is distributed and reaches the reticle 1 via the main condenser lens 4C. The lamp house 4A is provided with an exhaust hose 4B.
This illumination system 4 is a column 4E built on the column 2A.
And is fixed at a predetermined height position. The column 2A holding the projection lens 2 is fixed on the surface plate 8,
Is mounted on a base 10 via an anti-vibration suspension 9, and the base 10 is fixed on a floor 11 in a factory. Generally, a combination of the base 10 and the suspension 9 is called an anti-vibration table.

On the surface plate 8, an X stage 5 on which a holder for vacuum-sucking the wafer 3 is mounted, and a Y stage 6 on which the X stage 5 is mounted and moves on the base 7 in the Y direction. Provided. The X stage 5 moves one-dimensionally in the left-right direction in FIG. 1 and is driven by rotating the feed screw Sc by a screw rotation motor M ₀ fixed to the Y stage 6. The Y stage 6 is also provided with a feed screw and a motor, and moves in a direction perpendicular to the plane of FIG.

The laser interferometer L uses the light of the projection lens 2
Two length-measuring laser beams L from the X-axis direction perpendicular to the axis₁,
L_TwoAnd beam L₁Is X stage 5 (actually,
Moving mirror M fixed to the periphery on the upper Z stage)₁Hanging on
Directly incident. Beam L _TwoIs the lens barrel of the projection lens 2
Fixed mirror (reference mirror) M fixed to lower end_TwoIn the X-axis direction
Incident perpendicularly from. Laser interferometer L is fixed mirror M_TwoIn anti
Beam and moving mirror M₁And reflected back
Interference with the incoming beam, resulting in interference
By photoelectrically detecting the change in the brightness of the stripe, the moving mirror M
₁That is, the position information (or movement) of the wafer 3 in the X-axis direction
Amount) Se is output.

The position of the wafer W due to the movement of the Y stage 6 is detected by a laser interferometer having the same configuration. The stage is driven by a servo amplifier (differential circuit) Di.
After the value S ₀ of the target position is set, the position information Se of the laser interferometer L is added to the servo amplifier Di as a deviation signal. As a result, the servo amplifier Di drives the drive signal (voltage) S according to the distance between the current position of the stage and the target position.
And outputs to the motor M _0.

A part of the surface plate 8 has a mounting portion 13.
A wafer loader mechanism 13 is provided via the terminal c. The wafer loader mechanism 13 includes a cassette holding unit 13B for storing a cassette containing a plurality of wafers, and a transfer arm 13A for transferring one wafer taken out of the cassette to a holder on the X stage 5. Are provided. On the other hand, a reticle loader mechanism 12 is provided on a part of the lens-side column 2A via a mounting portion 12C. The reticle loader mechanism includes a reticle library section 12B for storing a plurality of cases for storing reticles used for exposure one by one, and a transfer arm 12A for delivering the selected reticle to a reticle stage. Is provided.

While the wafer loader mechanism 13 is exposing one wafer, the wafer loader mechanism 13 may continue to operate for returning the exposed wafer to the cassette, preparing a new wafer, or the like. Also, in the reticle loader mechanism 12, after the reticle exchange is completed and the exposure processing on the wafer is started, the motors and movable parts of the respective parts may operate in preparation for the next reticle.

In a typical stepper configured as described above, the measurement reference of the interferometer L is a fixed mirror M ₂ fixed to the lower end of the projection lens 2. This means that the interferometer L is assembled by selecting the position where the lower end side of the projection lens 2 is closest to the pattern projection image of the reticle 1 and where the image shift is most likely to occur. Such a configuration is well known in the art. Certainly, the interferometer L has a high ability to detect a deviation from a relative alignment position between the pattern projection image and the wafer 3, but does not monitor a positional deviation due to vibration of the pattern projection image itself. Therefore if no shaking the position of the fixed mirror M ₂ projection lens 2, if the shaking in the way of the reticle 1, but is determined to have statically determinate from measurement values of the interferometer L, actually the image Shake and image shift will occur.

The apparatus as shown in FIG. 1 includes various moving parts, and various kinds of moving parts have a large mass and a small mass. Further, this type of exposure apparatus is housed in an environmental chamber except for the lamp house 4A. The chamber has a vibration source such as a compressor blower to keep the environmental conditions (temperature, humidity, cleanliness, etc.) of the exposure apparatus constant. Among the movable parts inside the stepper and the vibration sources outside the stepper, the factors that greatly affect at the time of exposure are the X stage 5 and the Y stage 6.
Exercise. The stages 5 and 6 are the heaviest of the movable parts and move at a high speed in a stepping movement, so that the acceleration becomes high, and the reaction thereof causes the illumination system 4, the holding part (reticle stage) of the reticle 1, the projection lens 2, and the reticle loader. 12, the wafer loader 13 and the like are vibrated. These structures are all columns 1A, 2A, 4E
However, the vibration (sway) and convergence of the entire system change due to the rigidity and natural vibration of each column and structure.

As described above, since the reticle loader 12 and the wafer loader 13 may operate independently of the exposure operation for improving the throughput, vibration (fluctuation) may occur. Furthermore, the vibration of the floor 11 generated by the movement of the worker around the stepper or the movement of the self-propelled robot in the factory may be transmitted to the apparatus main body via the vibration isolator (9, 10). When the self-propelled robot automatically changes the wafer cassette in the wafer loader 13,
Unnecessary force may be applied to the cassette holding unit 13B to cause the wafer loader 13 to shake. In particular, floor vibrations having a long period that are stationary can be absorbed by the vibration isolating tables (9, 10), but cannot be sufficiently absorbed by the pulse-shaped vibrating vibrations and can be absorbed by the apparatus main body. It will be transmitted.

As described above, there are many vibration sources in the environment surrounding the stepper, and it is important to isolate these vibration sources from the stepper body as much as possible. As one of the measures, the reticle loader 12 and the wafer loader 13 are separated from the column 2A and the surface plate 8 of the stepper body,
Holding directly from the floor 11 is also conceivable. in this case,
Since the stepper body may be shaken as a whole on the anti-vibration tables (9, 10), there is a problem in positioning the transfer arms 12A, 13A when transferring the reticle or wafer. For example, when a wafer on the transfer arm 13A is transferred to a holder on the X stage 5, a mechanical configuration such that the wafer on the arm 13 and the holder always have a fixed positional relationship regardless of the swing of the entire stepper, Position correction and the like are required.

However, the portion of the vibration source which must move in the stepper body, especially the wafer stage, cannot be naturally separated from the stepper body. The movement of the wafer stage is the largest factor causing vibration and structural deformation of each part in the stepper main body, and is extremely close to the exposure operation in terms of time. Since the position of the center of gravity of the wafer stage changes with each alignment operation and exposure operation, the movement start position, stop position, movement speed (acceleration), etc. of the stage are obtained to analyze the local part fluctuation in the stepper body. It is possible to predict image shift and image blur, but for that purpose, it is necessary to perform structural analysis computer simulation based on huge data on rigidity and natural vibration of each part in the stepper body .

Therefore, in a specific embodiment of the present invention,
A vibration sensor, an accelerometer, a strain gauge, or a small interferometer (fiber interference) is provided on a portion of the stepper that causes vibration (shake) or deformation that deteriorates the relative alignment accuracy between the reticle 1 and the wafer 3 during exposure. And the like, and the start, interruption, and restart of the exposure operation are controlled in accordance with the detection signal. In another embodiment, the exposure control is performed by monitoring both the signal from the vibration or deformation detector and the expected settling time of the stage. In still another embodiment, a temporal change characteristic (period, change rate, etc.) of a transfer position error at the time of pattern exposure is determined from a detection signal of vibration (shake) or deformation, and an appropriate exposure is determined according to the change characteristic. The exposure time was varied without changing the amount.

FIG. 2 is a block diagram showing a configuration of a signal processing system and a control system commonly used in each embodiment. The same members as those shown in FIG. 1 are denoted by the same reference numerals. A light source ILS such as a mercury lamp is provided in the lamp house 4A of the illumination system 4 shown in FIG. The light source ILS is driven by the light source control system 20 to give a predetermined lighting power or a predetermined light emission luminance. The illumination light from the light source ILS passes through an interference filter or the like (not shown), and only a specific emission spectrum (g-line, i-line, etc.) for exposure is selected, and a fly-eye lens (optical integrator) for uniforming the illuminance distribution. It is incident on 4G. Fly eye lens 4G
The light from a number of secondary light sources formed on the exit side of the optical system enters the main condenser lens 4C via the lens system 4F, and illuminates the reticle 1 with a uniform illuminance distribution.

A shutter ST provided between the light source ILS and the fly-eye lens 4G is driven by a shutter control system 22 to open and close an optical path. The shutter control system 22 includes a circuit that integrates the light amount based on an output signal from a photoelectric detector 23 that detects the light amount of a part of the illumination light that has passed through the shutter ST, and that the integrated value is a target value ( And a circuit for outputting a closing signal for closing the shutter ST when the exposure time (equivalent to an appropriate exposure amount) is reached. A command to open the shutter ST is sent from the main control system 30. The output signal from the photoelectric detector 23 is also sent to the light source control system 20, and is used for stabilizing the light emission luminance of the light source ILS. Further, the photoelectric detector 2 is also provided at a position where the intensity of illumination light from the light source ILS is always detected independently of the shutter ST.
The output signal is sent to the light source control system 20 and used for power control of the light source ILS.

Although not shown in FIG. 1, a TTL alignment system ALG for detecting an alignment mark on the wafer 3 via the projection lens 2 is provided in FIG. The mark position information detected by the alignment system ALG is sent to the main control system 30, and the EGA (enhanced global alignment) of the wafer 3,
It is used to calculate the coordinates of the stepping position of the wafer stage according to an algorithm such as F / F (field-by-field). Coordinate values of the calculated stepping position is sent to the stage control system 24 including a differential circuit Di shown in FIG. 1 as a target value to drive the motor M ₀ as described above. The stage control system 24 has a function of calculating the amount of deviation between the calculated coordinate value of the stepping position and the current position of the stage measured by the interferometer L. The information ΔPS of the amount of deviation is used for image shift analysis. To the computer 25.
In the conventional apparatus, when the deviation .DELTA.PS falls within a predetermined allowable range and the servo drive of the wafer stage is completed, the stage control system 24 sends a signal indicating that exposure is enabled to the main control system 30. Was. However, in the present embodiment, whether or not exposure is possible, including confirmation that the deviation amount ΔPS falls within the allowable range, is entirely determined by the image shift analysis computer 2.
When it is determined in step 5 that the exposure is possible, the computer 25 sends a signal EX to that effect to the main control system 30 from the computer 25.

The image shift analysis calculator 25 calculates a substantial position shift (image shift) between the pattern image projected on the wafer 3 and the wafer 3 among the vibrating portion in the stepper or the structurally deformed portion. , Image blur) are input from n sensors S _{1 to} Sn provided in some of the portions that generate image blur. Figure 2 is the seven sensors S ₁ to S ₇ is provided, the sensor S ₁ is a fly-eye lens 4G
(Vibration) in the direction orthogonal to the optical axis of the illumination system, or deformation, and the fluctuation or deformation related to the tilt direction of the fly-eye lens 4G from the optical axis are detected, and the magnitude of the vibration (vibration) or deformation is detected. An output signal corresponding to the output signal is generated. Sensor S
₂ generates an output signal corresponding to the magnitude of the primary vibration of the condenser lens 4C (sway) and deformation, shaking and position of the sensor S ₃ is the X direction of the reticle stage RS, Y direction, Z direction (as well as the direction of rotation) An output signal is generated according to the magnitude of the deviation. Sensor S ₄ generates an output signal corresponding to the magnitude of the upper side of the projection lens 2 vibrations of the lens barrel portion (reticle side) (shake). Other sensors S ₅ and outputs a signal corresponding to the magnitude of the vibration (swaying) of the lens-side column 2A, the mounting portion 12 sensor S ₆ is for supporting vibration generated in the reticle loader 12, or a reticle loader 12
The sensor S ₇ generates a signal corresponding to a change (strain) in the stress applied to C, and furthermore, the sensor S ₇ detects the vibration generated in the wafer loader 13 or the mounting portion 1 supporting the wafer loader 13.
A signal corresponding to a change (strain) in stress applied to 3C is generated.

The above arrangement of the sensors S _{1 to} S ₇ is merely an example, and if there is a portion (a chamber or the like) that can be considered as a vibration source, it is preferable to provide a sensor there.
Further, each of the sensors S _{1 to} S ₇ is not necessarily the same type, and various types are appropriately selected according to the physical quantity to be detected. For example, when dealing with relatively large vibrations, a micro-position sensor or the like is preferable. When even a minute vibration (micron order) directly affects image shift, a small interferometer (using a semiconductor laser) is used. Good. When detecting structural deformation, a strain gauge (strain gauge) or an interferometer is used.

The relative positional deviation between the reticle 1 and the wafer 3 during exposure is caused by a mark on the peripheral portion of the reticle 1 and a mark on the peripheral portion of the shot area on the wafer 3 projected on the projection lens 2.
Can be detected by using a TTR (through-the-reticle) type alignment system, which detects simultaneously through the reticle. The TTR type alignment system currently in practical use has the ability to relatively quickly detect the relative displacement between the reticle mark and the wafer mark. However, the image shift does not always occur slowly during the exposure time, but may occur rapidly due to release of stress accumulated in a structure in the apparatus. TTR when image shift occurs slowly
It is also possible to deal with this by sequentially detecting the amount of deviation by the alignment system and forming a loop for correcting the position of the reticle stage RS or the wafer stage by feedback control.

Next, a first embodiment of the present invention will be described. In the first embodiment, the image shift analysis computer 25 sequentially inputs signals from the sensors Sn at the time of stepping, and should project the signals onto the wafer 3 by the projection lens 2 based on the overall correlation of the signals. A relative position shift characteristic between the image and the shot area on the wafer 3 is calculated in real time, and the position shift characteristic and the positioning characteristic (statically determined characteristic) of the wafer stage 5 measured by the laser interferometer L are calculated. Exposure to the shot area is started or interrupted based on only two or the static characteristics of the wafer stage 5.

[0033] FIG. 3 (A) shows the change characteristic of the measurement values of the laser interferometers L for X-direction (settling properties), the horizontal axis represents time t, the vertical axis represents the measurement position x _e. The measurement position x _e is 0
Point represents a stepping target position in the X direction of the wafer stage 5, ± x _s represents the tolerance with respect to the target position. In FIG. 3 (A), the wafer stage 5 is decelerated after moving at high speed toward the target position, a characteristic that converges within the allowable range ± x _s. Stage control system 24 outputs a deviation ΔPS from the target position to the computer 25, but the allowable range of the deviation amount ΔPS in this case is ± x _s. Calculator 2
5, when the mode using only measurement values of the laser interferometers L (mode using only the settling characteristics of the wafer stage) starts counting from the moment the deviation amount ΔPS is within the allowable range ± x _s, when out of the allowable range ± x _s by overrun, etc., it has so far of counting the zero reset hardware, or software. Then, the counted time t _C is set to a predetermined waiting time (for example, 0.1 to 0.1.
5 seconds) after the lapse above, computer 25 may command E to open the shutter ST only the exposure time T ₀ as shown in FIG. 3 (B)
X is sent to the main control system 30.

When each shot area on the wafer 3 is exposed by the step-and-repeat method (or the step-scan method), the center of gravity of the entire wafer stage 5 sequentially moves within the XY plane on the surface plate 8. Will be done. For this reason, the specific characteristics shown in FIG.
It does not become the same for all of the above shot areas, but slightly changes. That is, the convergence characteristics (amplitude and time) of FIG. 3A change according to the arrangement of the shot areas to be exposed on the wafer 3. Then, the image shift analysis computer 25 receives the array coordinate values of the next shot area stored in the main control system 30 and adjusts the waiting time t _c required for stepping to the next shot area to a more optimal value. Process to change to something. In determining the waiting time t _c , the wafer stage is stepped by a fixed distance, and a characteristic as shown in FIG. 3A is fetched into a waveform memory or the like, which is correlated with the coordinate position at each stepping and compared with each other. It is performed by an experiment or the like. Thus, according to the coordinate value of the shot area on the wafer 3,
By and setting time t _c a set shorter or longer should wait just after stepping, while pressing the extreme decrease in throughput, and can be exposed in a state of high resolution without such an image blur all shot areas Become.

It should be noted that the change of the waiting time t _c does not actually need to correspond one-to-one with each arrangement of the shot areas on the wafer 3, and the dimensions of the wafer (5 inches, 6 inches, 8 inches, etc.) In consideration of the above, the inside thereof is formed into an appropriate matrix (for example, 30 pixels independent of the size of the shot area).
partitioned in mm square), it may be given the same latency t _c for a plurality of shot areas existing centered on that one compartment.

As described above, the image shift analysis computer 2
5 is the internal optimum waiting time t _cSet and wait
Interval t_cHas elapsed, the signal S is internally stored as shown in FIG.
H1 is set to logic "1" and shutter ST is opened.
I will. By the way, the image shift analysis computer 25 uses various sensors.
ー S₁~ S₇Solves position shift characteristics based on information from
When used in the analysis mode, the calculator 25
S₁~ S₇Process the input information from
And each sensor S₁~ S₇Of vibration and stress detected by
The relative position shift characteristics between the projected image and the wafer 3
Is calculated almost in real time as shown in FIG. FIG.
In (C), the vertical axis indicates the position shift amount generated on the wafer.
x_iAnd its allowable range is ± x as in FIG.
_sIs determined. The position shift characteristics are shown in FIG.
As shown in FIG. 3, the convergence is not always required.
(A) does not always agree with the static determination characteristics of the wafer stage.
Absent. Also, FIG. 3 (C) matches the time axis of FIG. 3 (A).
The tolerance is ± x on the static settling characteristics of the stage.
_sEven if it enters, the position shift calculated by neuro calculation
In terms of characteristics, tolerance range ± x_sMay not be inside
You. Therefore, the computer 25 sets the allowable range in the position shift characteristic.
± x_sStart timing at the time of entering, within tolerance x_s
After the state of FIG. 3 has continued for a predetermined waiting time td1, FIG.
, The internal signal SH2 is set to logic “1”. Only
And the position shift amount x _iIs time T₁Tolerance after ±
x_sSignal SH2 at that point.
Set to logic "0". And the position shift amount x_iIs allowed
± x_sWhen the waiting time td2 elapses
And the signal SH2 is inverted to logic “1”. So Calculator 2
5 is the signal SH1 in FIG. 3B and the signal SH in FIG.
The logical product (AND) with 2 is calculated, and the logical product is "1"
The shutter ST is opened and exposure is performed only during
So that In this case, the shutter control system in FIG.
22 is a timer mode even if it operates in the light intensity integration mode.
It may be operated with. When in timer mode,
Time only when the ST is open,
When the target time is reached, exposure to one shot area
Complete.

By the way, image blur caused by vibration and stress is as follows.
Generally, it is likely to occur immediately after the completion of the stepping of the wafer stage. Therefore, first, the signal SH1 is set to logic “1”.
It is also possible to check whether or not the calculation has been made, and from the time when the logic becomes “1”, the calculator 25 may start the neuro calculation based on the input information of each of the sensors S _{1 to} S ₇ . FIG.
(C), in (D), after for the first time signal SH2 after stepping End is "1", since outside the allowable range ± x _s in a position shift amount x _i slight, that during this time the exposure is interrupted Become.

However, in a state where the signal SH2 becomes "1" for the first time and the exposure for one shot area is started (time T ₁ ), it is assumed that the image blur due to the vibration and the stress is extremely small. , Time T ₁
The waiting time td2 after elapse may be set shorter than the initial waiting time td1. When the light source ILS shown in FIG. 2 is a pulse light source such as an excimer laser, the light source control system 2
Since there is an oscillation trigger circuit in 0, the signals SH1 and S
Only when the logical product with H2 is true ("1"),
A plurality of pulse oscillation commands may be given to the oscillation trigger circuit.

Since the mechanical shutter SH usually has a constant operation delay (response delay), the signals SH1 and S
It is difficult to close the shutter momentarily when the AND output of H2 becomes "0". Therefore, as a mitigation measure against this, the position shift amount x _i is set within the allowable range ± x _s.
The disengaging from the inner to the outside to determine a bit in front, may be to narrow the range ± x _s when the position shift amount x _i is in the range ± x _s.

Conversely, as a technique for reducing the response delay of the shutter, a double blade shutter may be used as shown in FIG. In this type of exposure apparatus, a metal plate or the like is used for the shutter in order to suppress heat generation when blocking high-luminance illumination light from the light source ILS. Such a metal plate has a heavy weight, and when it is configured as a rotary shutter, there is a limit in suppressing its rotary inertia to a small value. Therefore, a sub-shutter, which has poor durability over a long period of time with respect to illumination light but has a reduced speed, is combined with a conventional shutter.

In FIG. 4, the shutter ST1 is at 45 °
This is a conventional rotary shutter in which minute blades are arranged in a circumferential circle every 45 °, and the illumination light IL is in a state of passing through a cutout portion of the rotary shutter. Conventionally, the illumination light IL is blocked only by rotating the shutter ST1 by 45 ° from the state shown in FIG. In such a rotary shutter, transmission and cutoff of the illumination light IL are switched only by rotating the shutter ST1 in one direction. In this embodiment, the sub-shutter ST2 having a high-speed response is provided in the optical path of the illumination light IL. This sub-shutter ST2 may be equivalent to a focal plane shutter made of a titanium thin plate (0.2 to 0.5 mm in thickness) used in a photographic camera or the like. This type of focal plane shutter has a very short time (operating time) until the shutter is fully opened or fully closed, and is about 10 to 5 msec. This value corresponds to 1/2 to 1/4 of the operation time of the rotary shutter ST1.

However, since the sub-shutter ST2 has poor durability, the timing of the drive section of each shutter is controlled so as to have an interlocking relationship with the main shutter ST1. First, from the shutter open state of FIG.
When the shutter L is shut off, the start of the closing operation of the main shutter ST1 and the start of the closing operation of the sub-shutter ST2 coincide with each other in terms of timing, or
Immediately after the closing operation of Step 2 is completed, the main shutter ST1
The timing is determined so that is closed.

When the shutter is opened, the main shutter ST1 is opened earlier and then the sub-shutter S is opened.
Open T2. Therefore, the shutter control system includes hardware or software that satisfies such a condition. Also, in the case of FIG.
Since S is on the side of the main shutter ST1, if the sub-shutter ST2 is closed when the shutter ST1 is opened, the blade of the sub-shutter ST2 is irradiated with the illumination light IL, and reflected light is generated therefrom. . Therefore, it is preferable to provide a photoelectric sensor that receives the reflected light, and establish a system that automatically opens the sub-shutter ST2 when the output signal level of the photoelectric sensor increases. The system can be used not only for the shutter opening operation at the start of exposure of the main shutter ST1 and the sub-shutter ST2, but also for the sub-shutter ST2 when the main shutter ST1 is opened halfway due to malfunction.
Can be prevented from being damaged by the illumination light IL.

By the way, in a state as shown in FIGS. 3C and 3D, when the vibration or the stress distortion is settled, the exposure operation may not be performed substantially. This was due to the vibration source of the apparatus within or device near around the allowable range ± x _s, is due to become image blur (amplitude is small) in a relatively short period. Therefore, as another embodiment, when the static setting characteristic of the wafer stage is detected as shown in FIG. 3B and the signal SH1 becomes "1", the amplitude and cycle of the vibration are rapidly increased from the change in the position shift characteristic. determined, even exceed the allowable range ± x _s slightly, when a periodic vibration, a light source ILS computer 25 to the light source control system 20 in FIG. 2
Such as a light source IL for reducing the brightness of the
A command to decrease the power supply to the S
(Or ST1, ST2) is output.

When the exposure amount is controlled in the light amount integration mode, a decrease in the luminance of the light source ILS increases the exposure time for obtaining an appropriate exposure amount. The long-time exposure is set so that one or more cycles of the vibration of the image blur exist. That is, the exposure time is set so as to include at least one cycle (preferably at least two cycles) of the vibration of the image blur, and the luminance of the light source ILS is reduced so as to obtain the exposure time. Such a method can be similarly used when the exposure amount control is performed in the timer mode.

Further, the decrease in the luminance of the illumination light is caused by the dimming means (N
A D filter, a mesh filter, etc.) may be inserted into the illumination light path. This way,
Even if image blurring occurs, the position of the pattern formed on the resist layer of the wafer 3 in the XY plane has a high probability of being at the center point of the vibration, and it is extremely unlikely to deviate from the designed position. Absent.

As described above with reference to FIG. 3, when the static state of the wafer stage is determined from the reading of the laser interferometer, depending on the relationship between the structure of the wafer stage and the stepping direction, the waiting time t _c , Alternatively, td1 and td2 may be set to different values. For example, in a structure in which the X stage 5 is mounted on the Y stage 6 as shown in FIG. 1, the mass of the movable body when the Y stage 6 moves is the same as when the X stage 5 moves. Naturally, it becomes larger than the mass of the movable body. Therefore, when only the X stage 5 moves and when only the Y stage 6 moves,
The degree of vibration and blur may be different. Therefore, when the wafer 3 moves in the X direction and when it moves in the Y direction by the step-and-repeat method or the step-and-scan method, the waiting time t _c shown in FIG. It is desirable that the waiting times td1 and td2 shown in (1) are changed and set in advance so that a more optimal state can be obtained.

In the above-described embodiment, the exposure condition is changed (long-time exposure) in accordance with the vibration and blur. However, another method for coping with the vibration and the image shift by changing the exposure condition will be described below. One method is to monitor the deviation amount of the measured value from the laser interferometer L from the target value as shown in FIG. 3A, and wait time t _c (in this case, it may be shorter than 0.1 second). When the exposure is performed by opening the shutter ST after the exposure, control is performed such that the illumination light amount on the reticle 1 is increased stepwise or continuously during one-shot exposure. That is, immediately after the start of one-shot exposure, the amount of illumination is kept low, and immediately before the end of exposure, the amount of illumination is increased. In general, image blur due to vibration or stress becomes sufficiently small after a predetermined time has elapsed after stepping is completed.Therefore, the amount of exposure is concentrated in a time region where image blur is determined to be sufficiently small, and some image blur remains. In such a time region, the exposure amount is set to be small. FIG. 5A shows an example of the illuminance change characteristic when the illumination light amount to the reticle 1 is continuously changed during one-shot exposure, and FIG. 5B shows the illuminance change characteristic when the illumination light amount is changed stepwise. An example is shown below.

From the characteristics shown in FIGS. 5A and 5B, 1
Or size and temporal changes in the illumination light amount to be applied during the shot exposure, the occurrence of image blur caused by vibration or stress, learning and monitored by a laser interferometer L, or various sensors S ₁ to S _7, etc. Alternatively, an optimal curve is set in advance by a method such as inspecting a resist pattern on a wafer exposed by trial printing or the like.
Or, when exposing shot areas on the wafer one after another,
Even if the state of the image blur (vibration) generated in the previous shot area is learned, the same image blur is predicted to occur in the next shot area, and control is performed to set a curve of the light amount change characteristic. Good.

A continuous and stepwise change in light quantity can be realized by disposing a rotating ND filter disk whose transmittance changes in the circumferential direction as shown in FIG. 5C in the illumination light path. At this time, if the rotation speed of the ND filter disk is changed,
It is possible to change a time characteristic on a change in light amount during one-shot exposure. Of course, the rotation of the ND filter disk and the opening (or closing) of the shutter ST are performed in synchronization. When a complete light shielding portion BS can be formed in a part of the filter disk as shown in FIG. 5C, this filter disk can be used also as the shutter ST.

When the light amount is changed stepwise as shown in FIG. 5B, the power supplied to the light source ILS by the light source control system 20 shown in FIG. Flash up). In FIG. 5B, the light amount is changed in two stages, but may be changed in more stages. Now, as another method of changing the exposure condition, a light source image (secondary light source image or the like) in an illumination optical system (from the light source ILS to the condenser lens 4C) is used.
When a stop that limits the area of the light source image, that is, a so-called illumination aperture stop (hereinafter referred to as a σ stop) is disposed on or near the surface where is formed, the aperture amount of the σ stop is made variable. Alternatively, a change in light amount may be obtained. In the optical path shown in FIG. 2, the σ stop is arranged on the exit side (secondary light source image side) of the fly-eye lens 4G, and can be formed by each of a large number (50 to 200) of element lenses constituting the fly-eye lens 4G. The number of secondary light source images can be
Are made substantially concentrically variable from the peripheral side toward the center side. σ aperture is 0.1 as its set value
It is determined so that about 0.7 is obtained. Where σ = 0.
7 is an area ratio (light source image area / pupil area) when the σ stop is fully opened and all of the secondary light source images of the fly-eye lens 4G are formed in the entrance pupil (Fourier transform plane) of the projection lens 2.
It has become. Therefore, if the value of the σ stop is changed from a smaller value to a larger value during the exposure of one shot, a time characteristic as shown in FIG. 6 can be obtained in terms of light quantity. When the opening amount of the σ stop is changed during the exposure of one shot as described above, while the σ value is small, an image in which the depth of focus is small and the edge of the pattern is relatively prominent is obtained, As the σ value increases, an image with a large depth of focus is obtained.

As described above, the method of changing the light amount as the exposure condition is effective in the step-and-repeat method in which the relative positional relationship between the reticle and the wafer is stopped for each shot and the exposure is performed. However, the method cannot be applied when the exposure is performed by the scanning method (relative movement between the reticle and the wafer) in which the light is irradiated in a slit-shaped or arch-shaped illumination area. However, when the light amount changes continuously as shown in FIGS. 5A and 6, it is possible to cope with this by changing the scan speed in synchronization with the change in the light amount (illuminance on the reticle).

[0053]

As described above, according to the present invention, the influence of vibration which deteriorates the positioning stability of the photosensitive substrate at the time of exposure can be avoided by waiting for a stabilization or by averaging (long exposure). In addition, the arrangement accuracy of the plurality of shot areas exposed on the photosensitive substrate is improved. Further, in the present invention, even during the exposure period, control for eliminating the influence of vibration (exposure interruption or the like) can be performed, so that there is an effect that the resolution of the exposed resist image can be prevented from lowering. Further, according to the present invention, the influence of vibration is specifically checked as image blur, and control is performed such that exposure is performed when the image blur is within an allowable amount, so that there is no waste of simply waiting for a long time, The decrease in throughput is also minimized. Further, the present invention can be similarly applied to an apparatus using a pulse laser beam as a light source which does not perform light quantity control by a shutter.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a schematic control system configuration of the apparatus shown in FIG. 1;

FIG. 3 is a graph showing static settling characteristics of a wafer stage and image blurring (position shift) characteristics when the influence of vibration is subjected to neuro calculation.

FIG. 4 is a perspective view showing a configuration of a double blade shutter.

FIG. 5 is a diagram illustrating a change characteristic of an illumination light amount and a configuration of a filter for varying the light amount.

FIG. 6 is a diagram showing a light amount change characteristic by a σ stop.

[Explanation of Signs of Main Parts]

1 reticle 2 projection lens 3 wafer 5,6 wafer stage 25 image displacement analysis for computer ST shutter ILS light source S ₁ to S ₇ vibration detection sensors such as strain

Claims (41)

(57) [Claims] 1. An exposure method for exposing a predetermined pattern onto a substrate, comprising: detecting vibration or deformation that causes a relative position shift between the pattern and the substrate; and detecting the position based on a result of the detection. The shift amount is obtained , and the position shift amount remains within the predetermined amount for the first predetermined period.
When it is settled, the position shift does not occur.
An exposure method characterized in that it is recognized as being present. 2. The exposure method according to claim 1, wherein the exposure is controlled so that the exposure is performed in a state where the position shift does not occur. 3. The apparatus according to claim 2, wherein the identification is performed based on a state of the position shift obtained based on a result of the detection, and the exposure control is performed based on the position shift state. 3. The exposure method according to 2. 4. The exposure method further comprises: detecting a static state of the substrate stage at the target position when the substrate stage on which the substrate is mounted is moved to the target position; 4. The exposure method according to claim 2, wherein the exposure is performed based on both the static state and the position shift state. 5. A state in which the position of the substrate stage after the movement is within a predetermined distance from the target position is indicated by the stationary state, and the amount of the position shift is within a predetermined amount. 5. The exposure method according to claim 4, wherein the exposure is performed when a certain fact is indicated by the position shift state. 6. The exposure method according to claim 4 , wherein the exposure is performed when the position of the substrate stage is continuously within the predetermined range for a second predetermined period. Wherein said first predetermined period and said second predetermined time period, the exposure method according to claim 6, characterized in that each different depending on the direction of movement of the substrate stage. 8. The exposure method according to claim 6, wherein the second predetermined period differs according to the target position. 9. The exposure method according to claim 6, wherein when the position shift amount becomes equal to or more than the predetermined amount after the start of the exposure, the exposure is interrupted. To 10. After interruption of the exposure, when the position shift amount falls continuously third predetermined time period in the predetermined amount in,
The exposure method according to claim 9, wherein the exposure is restarted. Wherein said third predetermined time period, the exposure method according to claim 10, wherein the shorter than between the first place <br/> periodically. 12. The exposure method further includes identifying periodicity of the position shift state. Even if the position shift state indicates that the position shift amount is equal to or more than the predetermined amount, the position shift state is determined. 6. The exposure method according to claim 5, wherein the exposure is continued if is periodic. 13. The exposure method according to claim 12, wherein when the continuation of the exposure is determined, the amount of illumination on the substrate is reduced to extend the period of the exposure. 14. The method of claim 13, wherein the position shift state, the exposure method according to any one of claims 1 to 13, characterized in that it is obtained based on the vibration or the modified sensed at a plurality of locations. 15. The method according to claim 15, wherein the pattern is formed on a mask, and the exposing method is a first exposing method in which the mask and the substrate are exposed in a stationary state, or the mask and the substrate are relatively moved. The method according to any one of claims 1 to 14, wherein the method includes one of a second exposure method for exposing while performing exposure.
The exposure method according to any one. 16. An exposure method for exposing a predetermined pattern on a substrate, comprising: a vibration or a deformation which causes a relative position shift between the pattern and the substrate; and an exposure method for exposing the substrate with the pattern. An exposure method comprising: obtaining a relationship with the illumination light amount of the light source; and changing the illumination light amount during the exposure period based on the relationship. 17. The exposure method according to claim 16, wherein the illumination light amount is changed continuously. 18. The exposure method according to claim 16, wherein the change in the amount of illumination is performed in a stepwise manner. 19. The method according to claim 19, wherein the pattern is exposed on a plurality of regions on the substrate, and the relationship in the region is set based on a detection result of the vibration or deformation generated at the time of exposing the region before the region. The exposure method according to claim 16, wherein 20. The method according to claim 20, wherein the exposing method includes exposing the mask on which the pattern is formed and the substrate while exposing the substrate relative to each other, and changing a speed of the relative movement according to a change in the amount of illumination light. The exposure method according to claim 17, wherein: 21. An exposure method, comprising: exposing a mask on which the pattern is formed and the substrate in a stationary state; moving a substrate stage on which the substrate is mounted to a target position; 16. The exposure device according to claim 15, wherein it is detected whether or not the position of the substrate stage after the movement is within a predetermined range from the target position, and if the position is within the predetermined range, the exposure is started. 19. The exposure method according to 18. 22. The exposure method according to claim 21, wherein the illumination light amount is larger immediately before the end of the exposure than immediately after the start of the exposure. 23. The method according to claim 1, wherein
A method for producing a circuit pattern using an exposure method . 24. A semiconductor device comprising : a semiconductor element;
Liquid crystal display element, including original wiring pattern
A method for manufacturing the circuit pattern body according to claim 23 . 25. An exposure device for exposing a predetermined pattern on a substrate.
In an optical device, a relative relationship between the pattern and the substrate
Detection to detect vibration or deformation that causes position shift
Means for detecting the position shift based on a detection result by the detection means.
The position shift amount is within a predetermined amount for a first predetermined period.
The position shift occurs when the
Identification means for recognizing that there is no
Exposure equipment characterized . 26. The method according to claim 26, wherein the exposure is performed when the position shift occurs.
Control means to control exposure so that
The exposure apparatus according to claim 25, wherein: 27. The detecting means, comprising:
Based on the position shift state obtained based on the result
Performing the identification, and the control means controls the exposure based on the position shift state.
The exposure according to claim 26, wherein light control is performed.
apparatus. 28. A substrate stage on which the substrate is placed
The substrate stage when the substrate stage is moved to a target position.
A stabilization detection hand that detects a stabilization state of the stage at the target position
And a control step, wherein the control means determines whether the detection result by the
The exposure control based on both of the identification results by the identification means.
28. The exposure apparatus according to claim 27, wherein the control is performed.
Place . 29. The substrate stage by the static detection means.
Is within a predetermined distance from the target position for a second predetermined period.
When it is detected that the control
29. The method according to claim 28, wherein a step performs the exposure.
Exposure apparatus according to the above . 30. The first predetermined period and the second place
The fixed period depends on the moving direction of the substrate stage.
30. The exposure apparatus according to claim 29, wherein the exposure apparatus is different.
Place . 31. The apparatus according to claim 31, wherein the control unit is executing the exposure.
When the position shift amount is equal to or more than the predetermined amount, the exposure
Is interrupted, and after the interruption, the position shift amount falls within the predetermined amount.
Restarting the exposure when the third predetermined period of time has elapsed
The exposure apparatus according to claim 29, wherein: 32. The detecting device according to claim 31 , wherein
26. The device according to claim 25, wherein the device is installed at a number of locations.
32. The exposure apparatus according to any one of claims 31 to 31. 33. The exposure device according to claim 31 , wherein:
A point that causes vibration or deformation that causes the position shift
At or near the location
An exposure apparatus according to claim 32. 34. The detecting means, wherein the predetermined pattern is
A reticle stage that holds the formed reticle
Projects the predetermined pattern on the substrate in the vicinity thereof
Projection lens barrel or its vicinity, fly in illumination system
Eye lens or its vicinity, condenser lens
Or a column supporting the projection lens
Near the reticle loader or its vicinity,
At or at multiple locations in the vicinity of the
An exposure apparatus according to claim 32 or 33, wherein
Place . 35. The identification means is provided at the plurality of locations.
Identification based on the detection result of the detection means
The method according to any one of claims 32 to 34, wherein
Exposure apparatus according to the above . 36. The pattern formed on a mask.
The exposure apparatus is configured to keep the mask and the substrate stationary.
A first exposure apparatus for exposing in a state, or the mask and the substrate
Any of the second exposure devices that expose while moving relatively
36. Any of claims 25 to 35, wherein
The exposure apparatus according to claim 1 . 37. An exposure device for exposing a predetermined pattern on a substrate.
In an optical device, a relative relationship between the pattern and the substrate
The vibration or deformation that causes the position shift and the pattern
In relation to the amount of illumination during the exposure period to expose the substrate in
Light amount that changes the illumination light amount during the exposure period.
An exposure apparatus comprising control means . 38. The exposure apparatus, wherein the pattern is formed
Exposure while moving the mask and the substrate relative to each other
A scanning exposure device, wherein the light amount control means continuously controls the illumination light amount
And changes the speed of the relative movement according to the change in the amount of illumination.
Further comprising speed control means for controlling the speed.
38. The exposure apparatus according to 37 . 39. The exposure apparatus, wherein the pattern is formed
For exposing the mask and the substrate in a stationary state
An optical device, wherein the light amount control means controls the illumination light amount continuously or stepwise.
And the substrate stage on which the substrate is mounted, and the substrate stage when the substrate stage is moved to a target position.
A stabilization detection hand that detects a stabilization state of the stage at the target position
Step, the exposure is performed when the substrate stage is within the predetermined range.
Exposure control means for performing
The exposure apparatus according to claim 37, wherein 40. The method according to claim 25.
Exposing the substrate with the pattern using an exposure apparatus of
Circuit pattern body manufactured by 41. A semiconductor device comprising : a semiconductor element;
Liquid crystal display element, including original wiring pattern
41. The circuit pattern according to claim 40 .