DETAILED DESCRIPTION OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention
By scanning the projection optical system synchronously with the EHA
Pattern on the reticle to the shot area on the wafer.
So-called slit scan method or step for sequential exposure
・ Exposure is performed with a projection exposure apparatus such as the AND scan method.
The present invention relates to a projection exposure method suitable to be applied to a case.
2. Description of the Related Art Semiconductor devices, liquid crystal display devices or thin film magnets
Used when manufacturing heads etc. using lithography technology
In a projection exposure apparatus, a reticle (or photo
Mask etc.) pattern is coated with photoresist etc.
Projection optics for projecting onto wafers (or glass plates, etc.)
Larger reticle without increasing strain on the system
Reticle to expose the wafer pattern onto the wafer.
Scanning the wafer synchronously with the projection optical system
Attention has been paid to a scan exposure method for performing more exposure. S
The can exposure method includes a so-called slit scan method and the like.
Combined with stepping movement and slit scan
There is a so-called step-and-scan method.
In general, in a projection exposure apparatus, the resolution is increased.
Depth of focus of the projected image by the projection optical system
And align the wafer surface with the image plane of the projection optical system.
Autofocus is important. Normal batch dew
In the case of the optical system, the auto focus is
Position of the projection optical system in the optical axis direction at a predetermined measurement point in the area
(Focus position), and the measured value is
This is done by adjusting the position. And the scanning exposure method
In a projection exposure apparatus of the type, exposure is performed by a scanning exposure method.
In this case, it is necessary to apply auto focus continuously.
In addition, the step-and-scan method
In a projection exposure apparatus, each shot area on a wafer
Exposure is performed by the scanning exposure method, and
The wafer is stepped during exposure to the slot area.
It is. In this case, conventionally, a system to be exposed on a wafer is used.
Non-scanning direction of the boat area (the direction perpendicular to the wafer scanning direction)
Position), the shot area to be exposed
It should have been completed by the time the exposure to was started.
SUMMARY OF THE INVENTION Scanning as described above
Even with an exposure type projection exposure apparatus,
You need to focus on the focus. However,
In the case of the can exposure method, the wafer is moved to the projection optical system.
Scanning in a predetermined scanning direction, the
The focus position is measured only within the lit exposure area,
Since the height of the wafer was adjusted based on this measurement result,
Has a predetermined upper limit for the response speed of the autofocus mechanism.
Tracking error between the wafer surface and the imaging surface
May occur. Therefore, the wafer is being scanned
Auto focus so that no tracking error occurs
It is desired.
 Furthermore, exposure of a photoresist or the like on a wafer
The material has an appropriate amount of exposure.
The brightness of bright light and the width of the slit-shaped exposure area are fixed.
Then, the scanning speed for obtaining the proper exposure amount is a predetermined value.
Is determined. Therefore, the wafer is exposed by the scanning exposure method.
When the wafer reaches its scanning speed.
Acceleration section (running section) is required, and at least
Autofocus is applied before passing the acceleration section
In addition, the step-and-scan method
Conventionally, in the case of a projection exposure apparatus, a predetermined shot
The wafer does not run until just before the area is exposed by the scanning exposure method.
There was a case that was moving in the inspection direction. Thus the wafer
If the is moving in the non-scanning direction,
There is a possibility that a tracking error may occur,
It is desirable to do so.
In addition, the step-and-scan method
In the projection exposure apparatus, the moving speed (scanning speed) of the wafer during scanning exposure
Wafer speed during stepping compared to
Autofocus when stepping because it is quite large
The operation may cause the wafer to oscillate unstable.
Was. In view of such a point, the present invention provides an exposure method using a scan exposure method.
When scanning, the wafer is scanned with small tracking error
Auto focus can be applied and the wafer
Auto focus is activated before the vehicle passes the acceleration section
It is an object to provide such a projection exposure method.
Further, according to the present invention, the wafer is moved in the non-scanning direction.
Tracking error of auto focus caused by moving
The purpose is to avoid harm. Furthermore, the present invention
When exposing by the step-and-scan method, the wafer
Auto focus even when the
Projection exposure so that the wafer operation does not make the wafer unstable
It is also an object to provide a method.
According to the present invention, there is provided:First scan
The exposure method uses a pattern on the mask (R) under predetermined illumination light.
Projection optics for projecting turn images onto a photosensitive substrate (W)
A first system perpendicular to the optical axis of the projection optical system.
In synchronization with scanning the mask (R) in the direction
(W) is scanned in a second direction corresponding to the first direction.
The pattern of the mask (R)
Expose a predetermined shot area (23) on (W)scanning
In the exposure method, the projection optical system (13)substrate
(W) onWith respect to the exposure area (22) in the second direction.
In the pre-reading area (24B) on the near side,Projection optical system (13)
Optical axis directionSubstrate (W)Measure the position ofWhen doing
IWhen the substrate (W) is moved to the scanning start position (FIG.
4 state),The prefetch area (24B) is stored in the predetermined
With the area (23)By projection optics (13)That dew
It is located between the light region (22).
In this case, the pattern of the mask (R) is
(W) scanning of the substrate started to expose on
After that, the prefetch area (24B) is stored in the predetermined shot area.
The second direction of the substrate (W) before reaching the area (23)
Positioning in the direction (Y direction) orthogonal to (X direction) is completed.
It is desirable to have. Also, the predetermined shot area
Immediately after the exposure to the region (23) is completed, the substrate (W)
Stop the position adjustment in the optical axis direction, and move to the next position on the substrate (W).
The substrate in its second direction for exposure to the boat area
To position the next scanning start position, and
After the positioning in the direction orthogonal to the second direction is completed,
It is possible to start adjusting the position of the substrate in the direction of the optical axis.
desirable.Next, the second scanning exposure method according to the present invention comprises:
In the same premise as the first scanning exposure method of the present invention,
To expose the pattern of the mask on the substrate
After starting to scan the substrate, the projection optics
Look-ahead on the near side in the second direction with respect to the exposure area on the plate
Before reaching the predetermined shot area.
Terminating the positioning of the plate in a direction perpendicular to its second direction
Things. Further, a third scanning exposure method according to the present invention
Are the same as in the first scanning exposure method of the present invention.
To the exposure area on the substrate by the projection optics
In the pre-reading area on the near side in the second direction,
Measure the position of the substrate in the optical axis direction of the science
Based on the measurement result, the position of the substrate in the optical axis direction
When performing the adjustment, the exposure to the predetermined shot area is completed.
Stops adjusting the position of the board in the direction of the optical axis after completing
To expose the next shot area on the substrate.
Stepping the substrate in a direction orthogonal to its second direction
Before starting the stepping of the board,
To expose the next shot area, the second
Starts accelerating movement of the substrate in the opposite direction
Of the substrate in the direction of the optical axis after the stepping of
The position adjustment is started.
According to the present invention, the exposure area on the substrate (W) is
Area (22) on the near side in the second direction (scanning direction).
Position in the optical axis direction of the projection optical system in the pre-reading area (24B)
(Focus position) is detected, and based on the detection result,
The focus position in the exposure area (22) of the substrate (W)
Adjusted. Therefore, the response speed of the autofocus mechanism
Has a predetermined upper limit and the substrate (W) is being scanned.
Also, autofocus is performed with high tracking accuracy. Ma
In addition, at the same time as autofocus, the surface of the substrate (W)
Auto leveling that adjusts the oblique angle to the tilt angle of the image plane
Can also be done.
Further, the substrate (W) is scanned at a predetermined constant scanning speed.
In order to accelerate up to a predetermined width Lac as shown in FIG.
An acceleration section is required. Then, at the start of scanning,
If the reading area (24B) is within the acceleration section,
That is, the look-ahead area (24B) is a show on the substrate (W).
Between the exposure area (23) and the exposure area (22).
Then, the shot area (23) passes through the acceleration section and is exposed.
When entering the area (22), the auto focus
Next, for example, in FIG.
Stepping in the direction (Y direction)
Even when (24B) is in the shot area (23),
The shot area (23) is still moving in the Y direction
And information on the focus position obtained in the pre-reading area (23).
Information is not information on the focus position at the original measurement point.
Auto focus can be applied accurately
Can not. To avoid this, the prefetch area (24
Non-scanning method of the substrate before B) enters the shot area (23)
The positioning (stepping) in the direction (Y direction) is completed
I just need to be.
In addition, the predetermined shot area (23)
Immediately after the completion of the exposure, the focus position of the substrate (W)
If you stop adjusting the focus (autofocus),
Substrate (W) is stepped faster than at the time of scanning exposure
And the detected focus position fluctuates greatly.
However, the substrate (W) does not vibrate unstable. So
After that, scanning of the substrate (W) in the scanning direction is started, and
After the stepping in the non-scanning direction is completed,
When starting to focus, the moving speed of the substrate (W) is
Auto scanning is stable because the scanning speed is lower than
Focus is performed.
BRIEF DESCRIPTION OF THE DRAWINGS FIG.
Will be explained. This embodiment uses the step-and-scan method.
To which the present invention is applied to an exposure method using a projection type exposure apparatus
It is. FIG. 1 shows a projection exposure apparatus used in this embodiment.
1, a reticle R includes a light source 1 and an illumination.
An illumination optical system including a light shaping optical system 2 and a relay lens 7;
To make the illumination area 21 of a rectangular slit shape more uniform.
Illuminated by illuminance, reticks in slit-shaped illumination area 21
The circuit pattern image of the wafer R is transmitted through the projection optical system 9 to the wafer W.
Transcribed above. ArF excimer laser as the light source 1
Or excimer laser light such as KrF excimer laser
Source, metal vapor laser light source, or harmonic generation of YAG laser
Pulse light source such as raw equipment, or mercury lamp and elliptical reflector
Can be used.
In the case of a pulsed light source, exposure is turned on or off.
Turn off by controlling the power supply from the pulse light source power supply.
In the case of a continuous light source, turning the exposure on or off
Switching is performed by a shutter in the bright light shaping optical system 2.
However, in the present embodiment, the movable blind (variable
(Field stop) 6, the movable blind 6
The exposure can be switched on or off by opening and closing
In FIG. 1, illumination light from a light source 1 is an illumination light.
The light beam diameter is set to a predetermined size by the bright light shaping optical system 2.
And reaches the fly-eye lens 3. Fly eye lens 3
A number of secondary light sources are formed on the exit surface of the
Illumination light from the source is collected by the condenser lens 4
Then, the movable blind (variable field stop) 6 is reached. Yes
The luminous flux passing through the opening of the moving blind 6 is a rectangular beam.
It becomes a light beam having a lit-shaped cross section, and the relay lens system 7
Incident on. The relay lens system 7 is connected to the movable blind 6
A lens system that conjugates the pattern formation surface of the icle R
The movable blind 6 has a width in the scanning direction (X direction) described later.
Blades (light-shielding plates) 6a and 6b defining scanning and scanning method
Blades defining the width in the non-scanning direction perpendicular to the
Shown). Blades that define the width in the scanning direction
6a and 6b are independent by drive units 5a and 5b, respectively
Is supported so that it can be moved in the scanning direction.
The two blades that define the width in the inspection direction are also driven independently
Supported to be able. Relay lens system 7 on both sides
This is a telecentric optical system,
Telecentricity is maintained in the light-shaped illumination area 21.
The reticle R of this embodiment is on the reticle stage 8
And is held in the form of a slit on the reticle R.
The image of the circuit pattern in the illumination area 21 of the projection optical system 9
Is projected and exposed on the wafer W through the. Slit-shaped illumination
A region on the wafer W conjugate to the bright region 21
A light area (exposure illumination field) 22 is set. Further, the projection optical system 9
In the two-dimensional plane perpendicular to the optical axis AX, the illumination area 21
Scanning direction of the reticle R (the direction parallel to the plane of FIG. 1).
The direction parallel to the optical axis AX as the + X direction (or -X direction)
The direction is defined as the Z direction. In addition, it is perpendicular to the X axis and
The straight non-scanning direction is defined as the Y direction.
In this case, the reticle stage 8 is a reticle.
The reticle R is driven by the stage driving unit 14 in the scanning direction.
(+ X direction or -X direction)
Of the driving units 5a and 5b and the driving unit for the non-scanning direction
Is controlled by the movable blind control unit 13. Retic
Stage drive unit 14 and movable blind control unit 13
The operation is controlled by the main control that controls the operation of the entire device.
System 15. On the other hand, the wafer W has a Z leveling stage.
10 and the Z leveling stage 10
X through fulcrums 11A to 11C that can be extended and contracted in the Z direction.
It is mounted on a Y stage 12. 3 fulcrums 11A
By adjusting the expansion and contraction amount of ~ 11C in parallel, Z level
The position of the ring stage 10 in the Z direction is adjusted, and three
By individually adjusting the amount of expansion and contraction of the fulcrums 11A to 11C,
Adjusting the tilt angle of the Z-leveling stage 10 (Levelin
G) is performed. The XY stage 12 is perpendicular to the optical axis AX
Position the wafer W in the X and Y directions
At the same time, the wafer W is scanned in the ± X direction at a predetermined scanning speed.
A light transmission system 16a is provided on the side of the projection optical system 9.
And a multi-point focus position detection system (hereinafter referred to as a light reception system 16b)
Below, it is called “multi-point AF sensor”). Many
In the point AF sensor, the light transmission system 16a moves from the optical axis AX to the point AF sensor.
On a predetermined plurality of measurement points on the wafer W
A slit image is projected, and the
The reflected light enters the light receiving system 16b and enters the light receiving system 16b.
Then, a plurality of slit images are re-imaged. From the light transmission system 16a
The emitted detection light strikes the photoresist on the wafer W.
It is light of a weak wavelength band. The surface of the wafer W
When displaced in the Z direction, the image re-formed in the light receiving system 16b is scanned.
Since the position of the lit image is laterally shifted, the light receiving system 16b is
Generates multiple focus signals corresponding to these lateral displacement amounts.
And supplies it to the signal processing system 17. In the signal processing system 17
Is the corresponding measurement point from the supplied focus signal.
The position in the Z direction (focus position) is calculated, and the calculated
The focus position is transmitted to the main control system 15. In this case,
A plurality of focus signals output from the optical system 16b are reserved.
The surface of the wafer W coincides with the image plane formed by the projection optical system 9.
Calibration so that each time
Has been done.
The main control system 15 includes the wafer stage driving unit 1
8 to control the operation of the XY stage 12.
Then, stepping and scanning of the wafer W are performed. And
At the same time, the main control system 15 is supplied from the signal processing system 17.
Based on the focus position information
The amount of expansion and contraction of the three fulcrums 11A to 11C via the moving part 18
By controlling, the Z leveling stage 10
Z coordinate and tilt of the held wafer W in the exposure area 22
Adjust the corner to the image plane. This allows auto focus
And auto-leveling are performed.
Then, as shown in FIG.
Through the projection optical system 9 by the scan exposure method
When exposing the shot area 23 on the wafer W by
Illumination area of width D set by one movable blind 6
Reticle R in the −X direction (or + X direction) with respect to
The speed V1Scan with. Also, the projection magnification of the projection optical system 9
Is a reticle, where β is, for example, 1/4, 1/5, etc.
+ X direction with respect to the exposure area 22 in synchronization with the scanning of R
(Or -X direction), the wafer WTwo(= Β · V1)so
Scan. As a result, the reticle R
Are sequentially transferred. In this embodiment, FIG.
By operating the one blade 6a, 6b, the illumination area
The positions of the edges 21a and 21b in the scanning direction 21 are
Each can be moved in the scanning direction, so the light-shielding band on the reticle R
Unnecessary patterns around ST are exposed on wafer W
Can be prevented.
In this case, in this embodiment, the multi-point AF shown in FIG.
From the light transmission system 16a of the sensor to the exposure area 22 on the wafer W
Central linear measurement area 24A and its exposure area 2
2 rows of linear prefetches arranged so as to sandwich 2 in the X direction
Each of the measurement points in the measurement areas 24B and 24C
Is projected. Figure 3 shows the slit on the wafer
Between the exposure area 22 and the measurement points by the multi-point AF sensor
In FIG. 3, a central portion of the exposure region 22 is shown in FIG.
Seven measurement points P in the measurement area 24A crossing in the Y directionA1~
PA7Are respectively projected on the slit image. Also, dew
Within the pre-reading area 24B on the −X direction side with respect to the light area 22
7 measurement points PB1~ PB7The slit image is projected on each
Similarly, the pre-read area on the + X direction side with respect to the exposure area 22
7 measurement points P in area 24CC1~ PC7Each pickpocket
Is projected. In this embodiment, the wafer is an arrow
When scanning is performed in the + X direction indicated by A, the measurement area 24
A, and a pre-read area on the −X direction side with respect to the exposure area 22
Of the focus position at a total of 14 measurement points in 24B
Autofocus and autoleveling using information
More specifically, a certain point Q on the wafer is at a certain point in time.
tQIn the area obtained under the pre-reading area 24B.
The scum position is only δZ compared to the focus position on the image plane
If low, point Q has reached the center of exposure area 22
Sometimes, the position of the Z leveling stage 10 in FIG.
Time tQShould be higher than the position at by δZ. Change
In addition, information on the focus position around the point Q is also obtained.
Therefore, leveling can be performed based on this information.
You. When the point Q reaches the center of the exposure area 22
The focus position obtained in the measurement area 24A is, for example,
If it is still lower than the image plane value, Z
The stage 10 may be moved in the Z direction. That is, dew
Focus position obtained in the measurement area 24A in the light area 22
The position information is the focus position obtained in the pre-read area 24B.
When the Z coordinate and tilt angle are controlled based on the
Used to correct minor errors.
On the other hand, the wafer runs in the -X direction indicated by the arrow B.
When inspected, the measurement area 24A and the exposure area 22
14 in total in the pre-reading area 24C on the + X direction side
Auto focus using information on the focus position at
Focus and auto leveling are performed. Here, FIG.
, The width of the exposure area 22 in the scanning direction (X direction)
From the edge portion of the exposure region 22 on the −X direction side.
The distance to the pre-read area 24B, and + X of the exposure area 22
The distance from the edge on the direction side to the pre-read area 24C is
FIG. 4 shows a shot area 23 on the wafer.
In order to perform the exposure for
3 shows the state set at the scanning start position. Figure 4
And the scanning direction of the wafer is set to the + X direction,
23 is an acceleration of width Lac in the -X direction with respect to the exposure region 22
It is separated by section 28. In the scanning direction of the acceleration section 28
The width Lac depends on the acceleration performance of the reticle stage 8 in FIG.
And settling time until the speed stabilizes. This
This is because the magnification β of the projection optical system 9 is the normal reduction magnification,
The stage 8 is higher than the XY stage 12 on the wafer side.
This is because scanning is performed quickly.
Next, in this embodiment, as shown in FIG.
Shot areas arranged adjacent to each other in the non-scanning direction on W
When exposure is performed by the scanning exposure method continuously in areas 23 and 27
An example of the combined sequence will be described with reference to FIG.
FIG. 5A shows the scanning direction of the reticle stage 8 in that case.
Moving speed V in (-X direction)RFIG.
The scanning direction (+ X direction) of the XY stage 12 on the EHA side
Moving speed VWXFIG. 5C shows the XY stage 1
2 moving speed V in the non-scanning direction (-Y direction)WYIs shown.
First, a time point P0In FIG. 4, as shown in FIG.
, The shot area 23 is set at the scanning start position.
As a matter of time P0Reticle stage 8 and wafer
Acceleration in the scanning direction in synchronization with the XY stage 12 on the
Start. Between the reticle stage 8 and the XY stage 12
The acceleration ratio is equal to the projection magnification β of the projection optical system 9.
When both stages reach the predetermined scanning speed,
Settling time T for stabilizationseTime P1From, run
Exposure exposure is started. The time required during this time is T 1Ie
The time T corresponding to the section 25 indicated by hatching in FIG.1
Lac is the distance that the XY stage 12 moves during
You. This distance Lac is the same as the width of the acceleration section 28 in FIG.
At this time, the reticle stage 8 and the XY stage
Page 12 at the start of exposure (time P1)
Therefore, it is not always necessary to synchronize during acceleration. Toes
Of the reticle stage 8 and the XY stage 12
The ratio with the acceleration in the X direction is not necessarily the projection magnification of the projection optical system.
It is not necessary to match the rate β. Then, TTwoJust scan
Time point P after exposure time has elapsedTwoCompletes the scanning exposure. Running
Simultaneously with the completion of the inspection and exposure, the XY stage as shown in FIG.
Page 12 starts stepping in the non-scanning direction. This
Time T required for steppingFourTime T betweenThreeTo
The deceleration of the tickle stage 8 is performed.
Deceleration of the XY stage 12 on the EHA side in the scanning direction, and
Of the shot area 27 is moved to the scanning start position.
As shown in FIG. 5C, the time TFourHas passed
Time point PFiveEnds stepping in the non-scanning direction
Then, the shot area 27 in FIG. 2 is exposed in the Y direction.
The region 22 substantially overlaps with the region 22. However, FIG.
As shown in FIG.FiveEarlier point PFourFrom
Reticle stage 8 and XY stage 12 on the wafer side
May start accelerating in the scanning direction. Then figure
3 using the focus position in the read ahead area 24C on the right side.
Auto focus (including auto leveling)
Time T6Time point P7From shot area
The scanning exposure for the area 27 is started. At this time,
Stepping end point P in the inspection directionFiveStart scanning exposure from
Time point P7By the time, the XY stage 12 on the wafer side scans
Distance in the direction, that is, the section 2 indicated by hatching in FIG.
In FIG. 6, let Lb be the distance that the XY stage 12 advances in the scanning direction.
In this case, as shown in FIG.
PFiveFrom time P6Positioning time T up toFiveOn the wafer side
The XY stage 12 is positioned in the non-scanning direction.
But the time TFiveNeed not be considered. this is,
Vibration amount when positioning the XY stage 12 in the non-scanning direction
Represents each measurement point P in FIG.A1Shape the slit image projected on
Each measurement point P is smaller than the luminous flux width of the detection light generated.
A1Is substantially unchanged. However,
Point P when positioning in the scanning direction is completely completed 6After
The distance that the XY stage 12 advances in the X direction may be Lb.
In the above sequence, first, FIG.
The width Lac of the acceleration section 28 is different from the exposure area 22 and the pre-read area.
When less than the interval Lp with the region 24B (Lac <Lp)
think of. At this time, at the start of scanning, the pre-read area 24B
Is in the shot area 23,
Information on the focus position at the end of the area 23 cannot be obtained. Obedience
Thus, the end of the shot area 23 enters the exposure area 22.
Error may cause autofocus following error
is there. Conversely, the auto focus
In order to perform scanning with high accuracy, be sure to set the
24B must be on the exposure area 22 side from the shot area 23
Must. This can be expressed as follows.
Lac ≧ Lp (1)
Next, the stepping end point P in the non-scanning directionFiveFrom dew
Light start point P7By the distance L the XY stage 12 travels
b is the distance Lp between the exposure area 22 and the pre-read area 24C.
If less than (Lb <Lp), the wafer is not
Because of the movement, each measurement point in the pre-read area 24C is
It will advance diagonally at the end of the cut area 27. This place
In this case, the focus position measured in the pre-reading area 24C is
Since the focus position is a position shifted laterally in the Y direction,
According to the measurement result, auto focus is performed accurately during exposure.
Is difficult. Therefore, stepping in the non-scanning direction
Performs autofocus accurately without being affected by
The condition is that the distance Lb is equal to or greater than the interval Lp as in the following equation.
Lb ≧ Lp (2)
However, also in this case, the condition of equation (1) must be satisfied.
I have to. Further, in this embodiment, the wafer side
XY stage 12 while XY stage 12 is stepping
Movement speed is fast and the response speed of the autofocus system follows
It may not be possible. So, during stepping,
It is desirable to turn off the operation of the focus mechanism. Ingredient
Specifically, in the sequence shown in FIG.Two
To lock the posture of the Z leveling stage 10 in FIG.
To turn off auto focus control and end stepping
Time point PFive(Or time point P6Auto Four)
With the scrap control turned on, scanning exposure is performed in the reverse direction. this
May cause unstable operation of the auto focus mechanism.
In the above embodiment, non-scanning is performed on the wafer W.
When shot areas 23 and 27 are aligned in the direction
However, shot areas are not arranged on the wafer W in the scanning direction.
In the case of the acceleration, for example, in FIG.FourYo
Before scanning, the XY stage 12 on the wafer side moves in the scanning direction.
The other operations are the same except for the ping operation. Ma
In the above embodiment, the stepping end time in the non-scanning direction
PFive(Or P6), The time point PFourTo scanning stage
Shows the sequence in which the acceleration of
Scanning exposure after stepping in all directions is completed
Needless to say, a sequence for starting acceleration of
The present invention is not limited to the above-described embodiment.
Various configurations can be taken without departing from the gist of the present invention.
According to the present invention, the pairing in the scanning direction on the substrate is performed.
The read-ahead area in front of the exposure area.
The position (focus position) in the optical axis direction is detected, and this detection is performed.
Since autofocus is performed using the result, the substrate
Auto scanning with small tracking error even when scanning
Focus can be applied. Start scanning the board
When moved to the position, the prefetch area
Between the exposure area and the exposure area, the substrate
While moving, the fore edge of the shot area
A scum position is detected in the prefetch area. Therefore, the show
Autofocus with small tracking error over the entire
There are advantages that can be applied.
Further, the mask pattern is exposed on the substrate.
After starting the scanning of the substrate, the pre-read area is
Before reaching the predetermined shot area of the second
Direction (non-scanning direction)
Is completed, the prefetch area is
It moves parallel to the scanning direction on the shot area. Therefore,
Auto focus with high accuracy over the entire shot area
Exposure to a predetermined shot area is completed.
Immediately after adjusting the position of the substrate in the optical axis direction,
Substrate for exposure to next shot area above
To the next scanning start position in the
After positioning in the direction orthogonal to the
When starting to adjust the position of the board in the optical axis direction,
Auto-off while moving at high speed by stepping
The focus turns off. Therefore, it is detected in the pre-read area
Even if the focus position changes at high speed,
The plate does not perform unstable operations.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing a projection exposure apparatus in which one embodiment of the present invention is implemented. FIG. 2 is a schematic perspective view for explaining a scanning exposure operation by the projection exposure apparatus of FIG. FIG. 3 shows a slit-shaped exposure area 22 and multipoint AF according to the embodiment.
It is a top view which shows the positional relationship with the measurement point by a sensor. FIG. 4 is a shot area 2 on a wafer at the start of scanning
FIG. 4 is a plan view showing a positional relationship between the exposure region 3 and a slit-shaped exposure region 22. FIG. 5 is a diagram showing moving speeds of a reticle stage and an XY stage on a wafer side when sequentially exposing shot areas adjacent to each other in a non-scanning direction by a scan exposure method. [Description of Signs] 1 light source 3 fly-eye lens 6 movable blind 7 relay lens system R reticle 8 reticle stage 9 projection optical system W wafer 10 Z leveling stage 12 XY stage 16a multipoint AF sensor light transmission system 16b multipoint AF sensor Light receiving system 22 of slit-like exposure area 23, 27 Shot area 24A Measurement area 24B, 24C Look-ahead area 28 Acceleration section
Continuation of the front page (56) References JP-A-6-196386 (JP, A) JP-A-6-260391 (JP, A) JP-A-8-37150 (JP, A) JP-A-4-350925 (JP) (A) JP-A-4-116414 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) H01L 21/027 G03F 7/20 521