JPH11145034A - Projection exposure apparatus and pulse emission method - Google Patents

Abstract

(57) [Problem] To provide an exposure operation such that when a door or the like disposed in a chamber or the like of a projection exposure apparatus is opened, light leaking from an opening of the door does not exceed an exposure radiation limit. And a projection exposure apparatus capable of safely and continuously performing various operations such as the above. A laser beam emitted in a pulse form from a laser oscillator (EL) illuminates a reticle (16) through a pipe (S), a beam shaping optical system (4), a fly-eye lens (6), relay lenses (11 and 13), a condenser lens (15) and the like. An image of the pattern PA of the reticle 16 is formed on the surface of the wafer 25 by the projection optical system 23, and projection exposure is performed. When the control unit 40 receives a signal from the door switch DSw and detects that a door disposed in the chamber 100 or the like has been opened, the control unit 40 widens the emission interval of laser light emitted in a pulse form from the laser oscillator EL. Dim. Accordingly, the laser beam leaking from the opened opening of the door does not exceed the exposure radiation limit, and the projection exposure operation can be continuously performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a projection exposure apparatus used for manufacturing a semiconductor device or a liquid crystal display device by a photolithography process and a pulse light emission method in an apparatus having a pulse light source.

[0002]

2. Description of the Related Art In a photolithography process for manufacturing a semiconductor element or a liquid crystal substrate, an exposure apparatus that exposes a pattern image of a reticle such as a mask onto a photosensitive substrate via a projection optical system is used. In recent years, further improvement in the degree of integration of semiconductor integrated circuits has been demanded, and in the photolithography process, a method of shortening the exposure wavelength of a light source for photolithography has been used as a method for enabling finer processing. It is considered. As one proposal, a projection exposure apparatus (excimer stepper) using a short wavelength excimer laser as an exposure light source has been developed.

Incidentally, the projection exposure apparatus is usually covered with a housing (chamber) to keep the temperature and humidity constant. The chamber also has the effect of blocking light leaking from a projection exposure apparatus that uses a laser as a light source, such as an excimer stepper, and prevents an operator from being exposed to such light.

The chamber is provided with a door for performing maintenance of the projection exposure apparatus or a door for exchanging a reticle or a photosensitive substrate used in the projection exposure apparatus. If the operator opens these doors while the excimer laser is oscillating, the operator may be exposed to laser light exceeding the safety standard value. In order to prevent this exposure, in the conventional excimer stepper, upon detecting that the door is opened, the interlock is instantaneously activated to stop the oscillation of the excimer laser.

In the above-described projection exposure apparatus, consider the light that may be exposed to the operator when the interlock does not operate. This light is not direct light emitted from a laser oscillator, but is due to light leaking from an illumination optical system for shaping and guiding a laser beam to a reticle or irregular reflection on the reticle surface. Therefore, the amount of light is weak compared to the amount of light applied to the reticle surface. However, the radiation limit for obtaining certification such as class 1 laser products, that is, AEL (Accessible E
mission limit), it often exceeded the regulation value, and the above-described interlock was activated.

[0006]

However, when the interlock is activated in the excimer stepper as described above,
The in-process photosensitive substrate housed in the excimer stepper may be defective. This will be described. A photosensitive material (photoresist) applied to a photosensitive substrate used in an excimer stepper has a property (exposure sensitivity) that depends on a standing time in a relatively short span. For this reason, when the interlock is activated and the interruption time of the exposure operation is prolonged, the line width of an IC obtained by resuming the exposure operation after the interlock is released and performing the developing process may vary, and sometimes a necessary circuit may be required. In some cases, no pattern was formed. Further, if the interlock is activated while performing alignment or the like using the excimer laser light as an illumination light source, the alignment operation must be stopped. For this reason, the operation rate of the projection exposure apparatus may be significantly reduced.

[0007] On the other hand, i without using a laser as a light source for illumination
In a line stepper or the like, it is common practice to set a reticle to be used in the next exposure operation in a holder (reticle library) during the exposure operation in order to improve the processing capability of the projection exposure apparatus. . When an operator who has performed such an operation of the i-line stepper opens and closes the door of the chamber during laser oscillation of the excimer stepper, the interlock may operate to cause the above-described problem.

An object of the present invention is to prevent light leaking from an opening of an opened door or the like from exceeding an exposure radiation limit when an operator opens a door or the like provided in a chamber or the like of a projection exposure apparatus. It is an object of the present invention to provide a projection exposure apparatus capable of continuously performing various operations such as an exposure operation.

[0009]

FIG. 1 shows an embodiment of the present invention.
The present invention will be described with reference to FIG. (1) According to the first aspect of the present invention, the predetermined pattern PA
Illuminating optical systems 1 to 6, 11 to 15 for illuminating original 16 on which is formed by light emitted from pulsed light source EL
The original 1 illuminated by the illumination optical systems 1 to 6 and 11 to 15
Optical system 2 for projecting pattern PA of No. 6 onto a photosensitive substrate
3; a housing 100 that covers the illumination optical systems 1 to 6, 11 to 15 and the projection optical system 23; and a projection exposure apparatus including lids DM, DR, and DW installed on the housing 100 so as to be openable and closable. Is done. Detecting means DSw for detecting opening / closing of the lids DM, DR and DW; and when the detecting means DSw detects that the lid DM, DR or DW is opened, the illumination optical systems 1 to 6, 11 to 15 The above-mentioned object is achieved by having the dimming means 40 for reducing the amount of illumination by the light source. (2) In the invention according to claim 2, the light reducing means 40
Is to reduce the illumination light amount by making the light emission cycle of the pulse light emission by the pulse light source EL longer than the light emission cycle before the detecting means DSw detects that the lid DM, DR or DW has opened. . (3) In the invention according to claim 3, the light reducing means 40
Is for reducing the amount of illumination by a dimming member ND inserted in the optical path of the light emitted from the pulsed light source EL. (4) In the invention according to claim 4, the detection means DSw detects that the lid DM, DR or DW is opened, and the original 16 is used in a state where the amount of illumination is reduced by the dimming means 40.
When the detecting means DSw detects that the lids DM, DR, and DW are closed while the pattern PA is sequentially projected and exposed on the photosensitive substrate 25, the detecting means DSw outputs the lids DM, DR, and DW. The dimming of the illumination light quantity by the dimming means 40 can be canceled after the completion of the projection exposure in the shot area where the projection exposure is performed when it is detected that the shutter is closed. (5) The invention according to claim 5 provides illumination optical systems 1 to 6,
The illuminance of the illumination light by the illumination substrates 11 to 15 is detected and integrated.
5. Illumination detection for performing projection exposure until the integrated illuminance in each of the shot areas on 5 reaches a predetermined value, and controlling the exposure amount in each of the shot areas to be constant irrespective of the dimming of the illumination light quantity by the dimming means 40 (6) The invention according to claim 6 is a pulsed light source EL
Image processing means 40 for inputting an image obtained by photographing an object illuminated by the camera and performing predetermined processing. The image processing means 40 includes a pulsed light source EL when the amount of illumination is not reduced. Irrespective of the light emission timing, an image is input in synchronization with the light emission timing of the pulse light source EL when the amount of illumination light is reduced. (7) The invention according to claim 7 is a pulse light source EL.
Optical systems 1 to 6 and 11 to 15 for guiding light emitted from
The present invention is applied to a pulsed light emission method in which pulsed light is emitted from a pulsed light source EL while being covered with a housing 100 having lids DM, DR, and DW that can be opened and closed. Then, when it is detected that the lid DM, DR or DW is opened while the pulsed light source EL emits a pulse, the light amount from the pulsed light source EL is reduced. (8) In the invention according to claim 8, in order to reduce the amount of light,
The light emission cycle of the pulse light emission by the pulse light source EL is made longer than the light emission cycle before detecting that the lid DM, DR or DW is opened. (9) The ninth aspect of the present invention is to insert a dimming member ND into an optical path of light emitted from the pulsed light source EL in order to reduce an exposure amount.

In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments of the present invention are used for easy understanding of the present invention. However, the present invention is not limited to this.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic external view of a projection exposure apparatus according to the present invention, and FIG. 2 shows a schematic internal configuration of the projection exposure apparatus according to the present invention. In FIG. 1, the chamber (housing)
Reference numeral 100 is intended to prevent dust on the main body of the projection exposure apparatus (details of the main body of the projection exposure apparatus will be described later) and to keep the temperature and humidity inside the chamber 100 constant. The laser light emitted from the laser oscillator EL that emits an excimer laser pulse proceeds inside the pipe S and is guided into the chamber 100 via the light transmission window 3. This laser light is used as a light source for later-described projection exposure and baseline measurement.

The chamber 100 is provided with several doors (lids) as described below. The maintenance door DM is a door that is opened and closed when maintenance of a later-described projection exposure apparatus main body (hereinafter, exposure apparatus main body) is performed. Reticle replacement door DR, wafer replacement door DW
Reference numeral denotes a door which is opened and closed when exchanging an original plate (reticle) and a photosensitive substrate (wafer) used when performing projection exposure in the exposure apparatus body. In addition to these doors, a detachable cover (not shown) is provided at an important part of the pipeline S for maintenance.

With reference to FIG. 2, the construction of the laser oscillator EL and the exposure apparatus main body disposed inside the chamber 100 will be described.

In a pipe S provided between the laser oscillator EL and the chamber 100, a mirror 1, a mirror 2 and the like are disposed at a bent portion thereof. Thereby, the laser light emitted from the laser oscillator EL is guided in the pipe S, and enters the inside of the chamber 100 through the light transmission window 3 provided in the chamber 100. The laser light is guided to the beam shaping optical system 4 by the mirror 5 and shaped into a laser light having a predetermined cross-sectional shape, and passes through the transparent portion AP provided on the turret plate TP.

The turret plate TP has a dimming plate ND and a transparent portion AP. The turret plate TP includes a motor MT1 that rotates based on a control signal issued from the control unit 40.
Driven by Then, depending on the stop position of the turret plate, the dimming plate ND or the transparent portion AP is located on the optical path of the laser beam emitted from the beam shaping optical system 4. Normally, as shown in FIG. 2, the transparent portion AP is located in the optical path of the laser beam. The function of the light reducing plate ND will be described later.

The laser light passing through the transparent portion AP of the turret plate TP is reflected by the mirror 7 and guided to the fly-eye lens 6. The fly-eye lens 6 is configured by bundling a large number of lens elements, and a plurality of light source images (secondary light sources) corresponding to the number of lens elements constituting the fly-eye lens 6 are provided on the exit surface side of the fly-eye lens 6. ) Is formed.

Light beams from a plurality of secondary light sources formed by the fly-eye lens 6 are split by a beam splitter 9 into two beams.
The reflected light flux is guided to the integrating exposure monitor 10, where the illuminance (intensity) of the light flux is detected and integrated. Detection by the integrated exposure monitor 10,
A signal that changes according to the integration result is input to the control unit 40. On the other hand, the transmitted light flux is transmitted through the relay lens 11 and the field stop 1.
2, reflected by the mirror 14 through the relay lens 13,
The light is collected by the condenser lens 15. As described above, the illumination optical system is formed by the fly-eye lens 6, the relay lenses 11 and 13, the field stop 12, the mirror 14, and the condenser lens 15. With this illumination optical system, an illumination area on the reticle 16 defined by the field stop 12 is illuminated with substantially uniform illuminance.

A predetermined reticle pattern (hereinafter referred to as a pattern) PA provided on the lower surface of the reticle 16 is illuminated by an illumination optical system, and is projected onto a wafer 25 by a projection optical system 23. As a result, the image of the pattern PA is
The photoresist formed on the predetermined area 5 and applied to the surface of the wafer 25 in advance is exposed, and the image of the pattern PA is transferred to the predetermined area (chip) on the wafer 25. At this time, the control unit 40 obtains the integrated amount of light to be exposed on a predetermined area on the wafer 25, that is, the exposure amount, based on the signal output from the integrated exposure monitor 10 described above.

The control unit 40 includes a maintenance door DM, a reticle replacement door DR and a wafer replacement door DW described with reference to FIG. 1, and a not-shown openable / closable cover provided in the pipeline S. A plurality of switches DSw that operate in conjunction with the opening and closing of the switch are connected (only one switch is shown in FIG. 2 in order to avoid complicated description). Control unit 40
Detects an open / closed state of the above-described door, cover, or the like by detecting a signal input from the switch DSw. Then, when detecting that any of the doors or covers (hereinafter, these doors or covers are simply referred to as “doors”) is opened while the laser light is emitted from the laser oscillator EL, the control unit 40 determines Laser controller L
A command is issued to C to extend the pulse emission interval. As a result, the energy density of laser light leaking from the opening of the opened door per unit time (irradiation energy amount of laser light applied per unit area) is reduced.

The reticle 16 is held and fixed to a reticle stage 18 by a reticle holder 17. The reticle stage 18 is mounted on the base 22 so as to move two-dimensionally along a plane (X and Y planes, the Y axis is perpendicular to the plane of the paper) orthogonal to the plane of the paper of FIG. A moving mirror 21 is fixed to the reticle stage 18, and laser light from the laser interferometer 20 is reflected by the moving mirror 21 to
Again. The laser interferometer 20 measures the position (movement amount) of the reticle stage 18 in the X-axis direction. The result of the reticle stage position measurement by the laser interferometer 20 is input to the control unit 40. The control unit 40 controls the position of the reticle stage 18 in the X-axis direction by driving the reticle stage driving motor 19 based on the position information.

A reticle mark RM for measuring a baseline is provided at the outer edge of the pattern PA provided on the lower surface of the reticle 16. Then, at the time of baseline measurement, light that has been incident back onto the projection optical system 23 from below the wafer stage 27 passes through the reticle mark RM, and
(Hereinafter referred to as a CCD camera) C1 using a solid-state imaging device such as a CMOS sensor or a CCD reflected by
Incident on. The signal of the image captured by the CCD camera C1 is transferred to the control unit 40, and baseline measurement is performed. The details of the baseline measurement will be described later.

The wafer 25 is held and fixed on a wafer stage 27 by a wafer holder 26. Wafer stage 2
Reference numeral 7 is provided so as to be two-dimensionally movable along a plane (X, Y plane) orthogonal to the paper surface of FIG. A movable mirror 31 is fixed to the wafer stage 27, and the laser light from the laser interferometer 30 is reflected by the movable mirror 31 so that the laser interferometer 3
Re-enter at 0. The laser interferometer 30 measures the position (movement amount) of the wafer stage 27 in the X-axis direction. The position information of the wafer stage 27 is input to the control unit 40. Based on the position information, the control unit 40 drives the wafer stage driving motor 29 to position the wafer stage 27 in the X-axis direction and the moving wafer stage 27. To control the speed and so on.

A reference plate 28 is fixed on the wafer stage 27. The position (height position) of the upper surface (surface) of the reference plate in the Z-axis direction is set to be substantially flush with the photosensitive surface (surface) of the wafer 25 placed on the wafer holder 26. A not-shown fiducial mark (details of the fiducial mark will be described later) is provided on the upper surface of the fiducial plate 28, and is used as a fiducial for positioning the wafer stage in the later-described baseline measurement, projection exposure, and the like. . Further, a projection optical system 2 is provided below the projection optical system 23.
A light projecting unit LE and a light receiving unit DT of an oblique incidence autofocus system (hereinafter, referred to as an oblique incidence AF system) for detecting a relative distance between the wafer 3 and the surface of the wafer 25 in the Z-axis direction are fixed. The light projecting unit LE and the light receiving unit DT are connected to the control unit 40.

At the lower end of the projection optical system 23, an off-axis microscope OA is fixedly mounted so that its optical axis is parallel to the optical axis of the projection optical system 23. The off-axis microscope OA incorporates an epi-illumination device and a CCD camera (both not shown).
The D camera is connected to the control unit 40.

In the projection exposure apparatus main body described above, the reticle stage 18 is moved to Y
It further includes a reticle stage driving motor for driving in the axial direction, and a laser interferometer for detecting movement of the reticle stage 18 in the Y-axis direction. The same applies to wafer stage 27. With these components, the reticle stage 18 and the wafer stage 27 perform position measurement and position control in the X-axis and Y-axis directions, respectively. In the following description, only the position measurement and position control in the X-axis direction will be described. .

The calibration operation in the exposure apparatus body configured as described above will be described. The calibration operation is classified into baseline measurement and autofocus calibration. Hereinafter, the baseline measurement will be described first, and then the autofocus calibration will be described.

-Baseline measurement-When the reticle 16 is mounted on the reticle stage 18, precise relative positioning between the reticle stage 18 and the reticle 16 is performed by a reticle loader (not shown). However, when reticle 16 is moved to reticle stage 1
When the reticle is mounted on the reticle 8, a slight displacement of the reticle mounting position may occur. Due to this displacement of the reticle mounting position, the image formation position of the pattern PA reduced and projected by the projection optical system 23 also shifts on the X and Y planes. In order to form a circuit pattern composed of a large number of layers (layers), superposition exposure using a plurality of different reticles is repeated for one wafer. At this time, if the mounting position of the reticle 16 varies, high-accuracy overlay exposure cannot be performed, and thus it is necessary to remove the variation in the mounting position of the reticle 16. When the origin position of the wafer stage 27 is determined, the wafer stage 27 is moved along the X- and Y-axis directions, and a mark of an aiming mark (not shown) provided at the center of the field of view of the off-axis microscope OA. The center is matched with the mark center of the reference mark FM provided on the reference plate 28. At this time, the position on the wafer stage indicated by the mark center of the aiming mark provided at the center of the field of view of the off-axis microscope OA and the pattern center of the pattern PA provided on the reticle 16 are positioned on the wafer stage by the projection optical system 23. Projected position, ie, pattern PA
, The projection center position of the pattern PA can be obtained with reference to the mark center of the reference mark FM. Obtaining this relative distance is the purpose of baseline measurement. Hereinafter, the procedure of the baseline measurement will be described with reference to FIGS.

FIG. 3 shows the same apparatus as the exposure apparatus main body shown in FIG. 2 (the chamber 100 and the like are not shown). FIG. 4 is an enlarged partial sectional view of the vicinity of the reference plate 28 of the exposure apparatus main body shown in FIG. 3 and 4, the same components as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. As shown in FIG. 4, a reference mark FM is provided on the surface of the reference plate 28. FIGS. 3 and 4 show that the wafer stage 27 moves in the + X direction in FIG.
3 shows a state where the optical axis Axp.3 is located at a distance H2. On the other hand, as shown in FIG. 3, the reticle 16 is moved so that the optical axis Axp of the projection optical system 23 passes near the pattern center of the pattern PA provided on the reticle 16.
Is mounted on the reticle stage 18. On the lower surface of the reticle 16, a reticle mark RM is provided together with the pattern PA, and the mark center of the reticle mark RM is located at a distance H1 from the pattern center of the pattern PA. For this reason, the mark center of the reticle mark RM is located at a distance of approximately H1 with respect to the optical axis Axp of the projection optical system 23.
To explain this, when the reticle 16 is mounted on the reticle stage 18, the mounting position slightly varies as described above.
xp does not always coincide with the pattern center of the pattern PA. Therefore, as described above, reticle mark RM
Is located at a distance of approximately H1 with respect to the optical axis Axp of the projection optical system 23. These distances H1, H2
Has a relationship of H1 = M · H2 when the projection magnification (reduction ratio) of the projection optical system is M. That is, the reference mark provided on the reference plate 28 and the reticle mark RM provided on the reticle 16 have a substantially conjugate positional relationship with respect to the projection optical system 23.

After driving the wafer stage as described above, the control unit 40 issues a command to the laser controller LC to cause the laser oscillator EL to emit a pulse of laser light. At this time, the control unit 40 drives an optical path switching unit (not shown) to guide the laser light emitted from the laser oscillator to be emitted from below the reference plate 28 (FIG. 4) via the light guide LG. The control unit 40 also inputs a signal of an image captured by the CCD camera C1.

The shape of the reference mark FM provided on the surface of the reference plate 28 is a cross-shaped slit pattern. A laser light pulsed by the laser oscillator EL is guided by a light guide LG below the reference plate 28. The laser light emitted from the light guide LG becomes parallel light by the collimator lens CL, passes through the slit pattern portion of the reference mark FM, and travels along the optical path LP1. Then, the light enters the projection optical system 23 in the reverse direction, travels along the optical path LP2, and is formed such that the image of the reference mark FM overlaps with the reticle mark RM provided on the lower surface of the reticle 16.

The image of the reference mark FM described above is
1 and a reticle mark RM via a CCD (FIG. 3).
Photographed by the camera C1. At this time, the CCD camera C1
FIG. 5 shows the state of the image picked up by. As shown in FIG. 5, reticle marks RMx and RMy are two parallel reticle marks.
The four line segments combine to form a roughly cross shape,
Projection images FM′x and FM′y of the reference mark FM provided on the reference plate 28 are positioned between two parallel lines.

The image signal shown in FIG. The control unit 40 performs image processing on the images F of the reticle marks RMx and RMy and the reference marks FMx and FMy.
The distances δ1x, δ2x, δ1y, δ2y from M′x, FM′y are obtained. By calculating these δ1x, δ2x, δ1y, δ2y, the relative distance between the mark center position of the reference mark FM provided on the reference plate 28 as shown in FIG. Can be.

Here, the synchronization between the imaging timing by the CCD camera C1 and the emission timing of the laser light emitted in a pulse form from the laser oscillator EL will be described. In a normal state, that is, when the door is closed, the laser oscillator EL emits light at a repetition rate of about 1,000 pulses per second. Therefore, the CCD camera C1
However, even in the case where field recording is performed at 60 fields / second as in a normal television camera, a clear image can be obtained without particularly adjusting the laser emission timing and the imaging timing of the CCD camera C1. on the other hand,
When the door is opened and the light emission interval of the laser light emitted from the laser oscillator is extended, the control unit 40 controls the light emission timing of the laser light and the CCD camera C1 to prevent the image captured by the CCD camera C1 from flickering. It is desirable to match the imaging timing. This allows CC
By making the exposure amounts of the odd-field image and the even-field image captured by the D camera C1 uniform, the flicker of the image is eliminated, and the accuracy of baseline measurement by image processing described later is maintained. It is not necessary to take such timing when the CCD incorporated in the CCD camera C1 is of the progressive scan type. That is, when frame recording is performed using a progressive scan CCD, after the CCD camera C1 starts imaging, when the exposure amount reaches a predetermined level, the imaging operation is stopped, and the image signal is sent to the control unit 40. Just enter it.

Next, a procedure for obtaining the distance between the position on the wafer stage indicated by the mark center of the aiming mark provided at the center of the field of view of the off-axis microscope OA and the mark center of the reference mark FM will be described. As shown in FIG. 4, the above-described off-axis microscope OA is fixed below the projection optical system 23. The off-axis microscope OA includes an epi-illumination device using a halogen light or the like as a light source,
An image pickup device for picking up an enlarged image by a microscope is built in together with the optical system of the microscope (both are not shown). As a result, the field of view of the off-axis microscope OA is illuminated by the epi-illumination device, and light reflected by a reference mark or the like located in the field of view again enters the off-axis microscope OA to form an image, which is imaged by the imaging device. Is done. The image data at this time is input to the control unit 40 and processed.

In FIG. 4, Axo is a straight line passing through the center of the aiming mark provided at the center of the field of view of the off-axis microscope OA and extending parallel to the Z axis. This aiming mark is designed such that its center is located on the optical axis of the off-axis microscope OA. That is, the straight line Axo is designed to coincide with the optical axis of the off-axis microscope OA. Actually, they do not always coincide with each other due to a manufacturing error or the like, but for convenience of description, the straight line Axo is referred to as an optical axis Axo of the off-axis microscope OA in the following description.

The optical axis Axo of the off-axis microscope OA is
In the state shown in FIG. 4, the reference mark FM is at a position of −δ (design value) with respect to the mark center position. The control unit 40 inputs a measurement value by the laser interferometer 30 (FIG. 3) while driving the wafer stage driving motor 29 (FIG. 3). Then, the wafer stage 27 is moved by the distance δ in the −X direction based on the measurement value by the laser interferometer 30 (FIG. 3).
Then, the optical axis Axo of the off-axis microscope OA substantially coincides with the mark center position of the reference mark FM. Reference plate 28
The reference mark FM provided in the off-axis microscope O
A is illuminated by an epi-illumination device (not shown) built in A. Then, an enlarged image of the reference mark FM enlarged by the off-axis microscope OA is imaged together with the aiming mark by an imaging device (not shown) built in the off-axis microscope OA. An example of the image at this time is shown in FIG. In FIG. 6, the aiming marks OAx and OAy have a substantially cross shape in which four parallel two line segments are combined like the reticle mark RM described above. Then, an enlarged image FM "x, FM" of the reference mark is formed between each two parallel lines.
y is located. The image signal shown in FIG.
0 is input and image processing is performed. And aiming mark OA
x, OAy and enlarged images FM "of the reference marks FMx, FMy
x, distances from FM "y δ3x, δ4x, δ3y, δ4y are obtained. By obtaining these δ3x, δ4x, δ3y, δ4y,
The actual value of the positional relationship between the mark center of the reference mark FM shown in FIG. 4 and the optical axis Axo of the off-axis microscope OA can be obtained. By finding the actual value of this positional relationship,
It is possible to determine where the mark center of the aiming mark of the off-axis microscope OA indicates based on the mark center of the reference mark FM.

The measurement described above is called baseline measurement. That is, the projection center position of the projected image of the pattern PA provided on the reticle 16 on the wafer stage is
The center of the aiming mark of the off-axis microscope OA is obtained by obtaining the position indicated by the center of the aiming mark of the off-axis microscope OA based on the center of the mark of the reference mark FM and the center of the mark of the reference mark FM. With reference to the position on the wafer stage, it is possible to determine where the center position of the projected image of the pattern PA is.

After performing the baseline measurement as described above, the control unit 40 moves the wafer stage 27 so that the center of the reference mark FM is located at the position indicated by the center of the aiming mark of the off-axis microscope OA. Then, based on the above-described baseline measurement value, the control unit 40
Calculates the projection center position of the pattern PA on the wafer stage 27.

Autofocus Calibration Prior to the description of the autofocus calibration, the oblique incidence AF system will be described with reference to FIG. The oblique incidence AF system transmits a laser beam to the surface (photosensitive surface) of the wafer 25.
, And a light receiving unit DT that receives the laser beam reflected by the surface of the wafer 25. Both the light projecting unit LE and the light receiving unit DT are connected to the control unit 40. In the oblique incidence AF system configured as described above, a laser beam is emitted from the light projecting unit LE based on a light emission command from the control unit 40, and this laser beam is reflected on the surface of the wafer 25 and is transmitted to the light receiving unit DT. Incident. At this time, a detection signal corresponding to the position of the wafer 25 in the Z-axis direction is input from the light receiving unit DT to the control unit 40. The control unit 40 drives an actuator (not shown) based on a signal input from the light receiving unit DT, moves the wafer stage 27 up and down, and moves the imaging surface of the projection optical system 23 and the surface position (photosensitive surface) of the wafer 25 to the position. So-called chip leveling is performed. This is the autofocus operation by the oblique incidence AF system. As the light emitted from the light projecting unit LE of the oblique incidence AF system, a He—Ne laser or the like in a wavelength region where the photoresist applied to the wafer 25 has no sensitivity is used. Thereby, so-called fogging of the photoresist can be prevented.

The relative distance in the Z-axis direction between the projection optical system 23 and the wafer 25 can be detected by the above-mentioned oblique incidence AF system. On the other hand, the position in the Z-axis direction of the pattern PA provided on the reticle 16 mounted on the reticle stage 18 can vary depending on the reticle mounted, and accordingly, the image plane ( The focal plane can also vary. On the other hand, the oblique incidence AF does not directly determine the focal plane position of the projection optical system 23 but measures the relative distance between the photosensitive surface of the wafer 25 and the projection optical system 23. Therefore, when the reticle mounted on the reticle stage 18 is replaced, it is necessary to update the reference value of the relative distance between the wafer surface and the projection optical system 23 detected by the oblique incidence AF system. This is the auto focus calibration. This auto focus calibration is performed by the control unit 4 based on an instruction from the operator.
Automatically done by 0.

The auto focus calibration will be described with reference to FIGS. In FIG. 7, the reticle mark R is located at a distance H3 in the X-axis direction from the pattern center of the pattern PA provided on the reticle 16.
M1 is provided. The reticle mark RM1 is a slit pattern having a predetermined shape.

Reference plate 2 fixed on wafer stage 27
In FIG. 8, a reference mark FM1 for autofocus calibration is provided as a slit pattern similarly to the reticle mark RM1 described above. The slit pattern shapes of the reticle mark RM1 and the reference mark FM1 are similar, and the similarity ratio matches the projection magnification of the projection optical system 23. A sensor PD is provided below the reference mark FM1, and the reference mark FM is provided from above.
A signal corresponding to the amount of light that enters the sensor PD through one slit pattern is output. The sensor PD is connected to the control unit 40.

At the time of auto-focus calibration, the control unit 40 drives the wafer stage drive motor 29 to move the wafer stage 27 in the X-axis direction. Then, as shown in FIG. 8, the position of the wafer stage 27 is determined so that the distance between the projection center position C of the projection image of the pattern PA provided on the reticle 16 and the mark center position of the reference mark FM1 is H4. The dimensional ratio between H3 and H4 is equal to the projection magnification of the projection optical system 23. That is, when the projection magnification of the projection optical system 23 is M, H3 = M ·
It has the relationship of H4. Thereby, the slit pattern of the reticle mark RM1 provided on the reticle 16 is projected by the projection optical system 23 onto the slit pattern of the reference mark FM1.

At the time of auto focus calibration, the control unit 40 issues a light emission command to the laser controller LC. Then, while driving an actuator (not shown) to move the wafer stage 27 in the Z-axis direction,
An output signal from the sensor PD is detected. The output signal from the sensor PD indicates the maximum value when the light transmitted through the slit pattern of the reticle mark RM1 forms an image on the surface of the reference plate 28 by the projection optical system 23. This is because when the image formed on the reference plate by the projection optical system 23 becomes sharpest through the slit pattern of the reticle mark RM1, the amount of light transmitted through the slit pattern of the reference mark FM1 becomes the largest. Because. Conversely, as the image blurs, the amount of light incident on the sensor PD is regulated by the slit pattern of the reference mark FM1, and accordingly, the output of the sensor PD also decreases.

The control unit 40 issues a laser light emission stop command to the laser controller LC while detecting the focal position of the reticle mark RM1 formed by the projection optical system 23 as described above. Subsequently, the control unit 40
Laser light is emitted from the light projecting unit LE of the oblique incidence AF system, and a signal is input from the light receiving unit DT and stored. The value of the signal stored here becomes a new reference value of the oblique incidence AF system. The control unit 40 ends the auto focus calibration.

In the auto-focus calibration described above, when it is detected that the door has been opened while the laser beam is emitted from the laser oscillator EL (FIG. 7) in a pulse shape, the control unit 40 sets the laser controller. A command is issued to the LC to extend the pulse emission interval. Then, the control unit 40 sets the Z
The moving speed in the axial direction is reduced, and a signal output from the sensor PD is input in synchronization with the laser emission timing. As a result, autofocus calibration can be performed with the same accuracy as when laser light is emitted at regular pulse emission intervals.

As described above, in both the baseline measurement and the autofocus calibration, the laser light pulsed from the laser oscillator EL is used as the illumination light. Then, in response to detecting that the door has been opened while the laser beam is being emitted from the laser oscillator, the control unit 40 operates the interlock to extend the pulse emission interval of the laser beam. As a result, the laser light leaking from the opening where the door is opened is exposed to the radiation limit (AE).
L). On the other hand, since the baseline measurement or the autofocus calibration is continuously performed, the operation rate of the projection exposure apparatus does not greatly decrease.

Next, an exposure operation performed by the exposure apparatus according to the embodiment of the present invention will be described.

FIG. 9 is a diagram showing a sequence when exposure is performed by the projection exposure apparatus according to the embodiment of the present invention. The present exposure apparatus collectively illuminates the whole area of the pattern PA provided on the reticle 16 of the exposure apparatus shown in FIG. In this method, 25 predetermined regions (chips) are exposed. The exposure operation and the operation of moving the wafer stage 27 by a predetermined amount on the X and Y planes are alternately and sequentially repeated to project a plurality of circuit patterns on the wafer 25. Among these operations, FIG. 9 shows only the sequence of the exposure operation, and the illustration of the sequence relating to the movement of the wafer stage 27 performed during the exposure operation is omitted.

The exposure sequence shown in FIG. 9 is illustrated with time on the horizontal axis. The vertical axis shows the following operations and states in order from the top. (A): Laser controller L from control unit 40 (FIG. 2)
C (FIG. 2) Oscillation control signal (b): Excimer laser pulse emission timing (c): Predetermined area (pattern PA) of wafer 25 (FIG. 2) detected by integrating exposure monitor 10 (FIG. 2) (D): Insertion / retreat state of the dimming plate ND (FIG. 2) into the optical path of the excimer laser (e): From the door switch DSw (FIG. 2) Control unit 40
(Fig. 2) State of signal emitted

Hereinafter, an exposure sequence in the projection exposure apparatus according to the embodiment of the present invention will be described with reference to FIGS.

At timing a1, the control unit 40 issues an oscillation start command to the laser controller LC (a), and in response to this, the laser oscillator EL emits laser light at a normal pulse emission interval (b). This allows
Exposure in a predetermined area on the wafer 25 is started. The control unit 40 starts integration of the signal input from the integration exposure monitor 10 (c). The control unit 40 determines the timing b1
In step (1), it is detected from the signal input from the integrated exposure monitor 10 that the integrated exposure amount has reached the predetermined amount E before reaching the target integrated exposure amount F, and the turret plate TP is rotated by a predetermined angle by controlling the motor MT1 to reduce the amount. The light plate ND is positioned on the optical path of the laser light (d). When the dimming plate ND is inserted into the optical path of the laser light (timing c1), the control unit 40 issues an instruction to the laser controller LC to temporarily stop the oscillation. This is to prevent laser light from being emitted during switching of the dimming plate, thereby preventing illumination unevenness from occurring. The illuminance of the laser beam is attenuated when passing through the dimming plate ND, thereby reducing the increasing speed of the integrated exposure amount as shown in the chart of FIG. Subsequently, the laser light is emitted at the same pulse emission interval (b). The control unit 40 issues an oscillation stop command to the laser controller LC upon detecting that the integrated exposure amount has reached the target integrated exposure amount F based on a signal input from the integrated exposure monitor 10 at the timing d1 (a ). In response to this, the laser controller LC stops laser oscillation. Control unit 40
Also, at the timing e1, the motor MT1 is controlled to retract the light reducing plate ND from the optical path of the laser light. In the above exposure sequence, by inserting a dimming plate in the optical path of the laser light to reduce the increase amount of the exposure amount per one pulse of the laser light, it is possible to improve the control accuracy of the exposure amount for the following reasons. it can. That is, the amount of change in the exposure amount per pulse emission of the laser light emitted in a pulse form from the laser oscillator EL is reduced, so that the exposure amount can be finely adjusted, and the exposure amount can be controlled with higher accuracy. Accuracy can be obtained. In addition, since the variation in the energy amount per one pulse emission is reduced by reducing the amount of light by the light reducing plate, the variation in the exposure amount can be reduced.

With the above operation, one exposure operation is completed.
The controller 40 controls the wafer stage driving motor 29 to move the wafer stage 27 by a predetermined amount, and prepares for the next exposure operation.

The sequence described above is for the normal exposure operation, that is, when the door (FIG. 1) is not opened during the exposure. However, the operation when the door is opened during the exposure is described below. The description will be continued with reference to FIG.

At timing a2, the control unit 40 issues an oscillation start command to the laser controller LC (a), and the laser oscillator EL emits laser light at a normal pulse emission interval (b). At the timing b2, the door switch DSw is operated because the door is opened, and a signal from the door switch DSw is output to the control unit 40 (e). At this time, the control unit 40 controls the laser controller L
A command to extend the pulse emission interval of the laser light is issued to C, and the pulse emission interval emitted from the laser oscillator EL is extended as shown in the chart of FIG. As a result, laser light leaking from the opening where the door is opened is A
Never exceed EL. At timing c2, a signal from the door switch DSw is received, and the control unit 40 detects that the door opened at the timing b2 is closed, and sets the pulse emission interval of the laser light to the laser controller LC as normal. Issue a command to return to the interval. The control unit 40 detects that the exposure amount has reached the predetermined value E based on the signal input from the integration exposure monitor 10 at the timing d2, and thereafter performs the timings e2 to e2 in the same manner as the operations at the timings b1 to e1 in FIG. g2 exposure control is performed.

As described above, when the control unit 40 detects that the door is opened, it activates the interlock to extend the pulse emission interval of the laser light, and the laser leaks from the opening where the door is opened. The exposure operation is continued while preventing the light from passing through the AEL. For this reason, the exposure operation is not interrupted, and the wafer stocked inside the chamber 100 (FIG. 1) does not become defective.

Incidentally, the illuminance of the laser beam leaking from the opening where the door is opened may differ depending on the door, such as the maintenance door DM, the reticle replacement door DR, and the wafer replacement door DW. In this case, by changing the pulse emission interval in accordance with the illuminance of the leaked laser light, the operating rate of the projection exposure apparatus can be maximized without the leaked laser light passing through the AEL.

In the above description of the embodiment, an example has been described in which the pulse emission interval of the laser light is extended so that the leaked laser light does not pass through the AEL. Instead, the dimming plate ND is used. It can also be dimmed. That is, when it is detected that the door is opened before the exposure operation or during the exposure operation, the light may be dimmed by inserting the dimming plate ND into the optical path of the laser beam. At this time, the optical density of the light reducing plate ND is set so that the laser light leaking from the opening of the opened door does not exceed the AEL. Although the integrated exposure amount is detected by the integrated light amount monitor 10, the transmittance variation of the light reducing plate ND is large. Therefore, each time one shot or one wafer is exposed, the transmittance of the light attenuating plate ND is measured prior to the exposure.
It is desirable to measure at zero.

In the above embodiment, an example has been described in which the control unit 40 stops the oscillation of the excimer laser as the integrated exposure amount on the wafer 25 reaches the target integrated exposure amount F. Instead of this, a shutter (not shown) may be inserted in the optical path of the excimer laser light to block the excimer laser light.

-Second Embodiment- A second embodiment of the present invention will be described with reference to FIGS. Although the projection exposure apparatus according to the first embodiment shown in FIG.
The projection exposure apparatus according to the second embodiment shown in FIG.
It is of the scan exposure type. Note that the same components as those of the projection exposure apparatus of the collective exposure system according to the first embodiment shown in FIG. 2 and the like are denoted by the same reference numerals, and description thereof will be omitted. Also, the procedure of the baseline measurement or the autofocus calibration is the same as that of the projection exposure apparatus according to the first embodiment, and the description thereof will be omitted.

In FIG. 10, among the light beams from the plurality of secondary light sources formed by the fly-eye lens 6, the light beam divided and reflected by the beam splitter 9 is guided to the light amount monitor 10A to be irradiated with the illuminance of the light beam. (Intensity) is detected. A signal corresponding to the illuminance detected by the light amount monitor 10A is input to the control unit 40. The control unit 40 controls the light amount monitor 1
The intensity of the laser light emitted from laser oscillator EL is adjusted to be constant based on the signal input from 0A. The variable field stop 12A is driven by a motor MT2. Then, based on the control signal from the control unit 40, the motor MT2
Rotates, whereby the illumination area on the pattern PA is adjusted.

Here, the scan exposure method will be described. The scan exposure method is an exposure method that exposes a wafer while driving the reticle stage 18 and the wafer stage 27 in opposite directions along the main scanning direction (X-axis direction). At this time, the ratio between the moving speed Vr of the reticle stage and the moving speed Vw of the wafer stage is as follows, where M is the projection magnification (reduction ratio) of the projection optical system.
−MVw. Then, the wafer 16
Is irradiated with a slit-shaped (rectangular) illumination light defined by the variable field stop 12A to form a slit-shaped image field on the wafer 27,
As described above, reticle stage 18 and wafer stage 2
7 is driven to perform exposure.

The exposure sequence of the projection exposure apparatus of the scan exposure system (hereinafter referred to as a scan exposure machine) will be described with reference to FIGS. The exposure sequence in FIG. 11 is illustrated with time on the horizontal axis, similarly to the sequence of the projection exposure apparatus of the collective exposure method shown in FIG. The vertical axis indicates the following operations and states in order from the top. (A): Drive control state of reticle stage 18 (drive speed of reticle stage 18) (b): Oscillation control signal issued to laser controller LC from control unit 40 (c): Pulse emission timing of excimer laser (d): State of signal issued from door switch DSw to control unit 40 (e): Transfer timing of defective shot (chip) information

At timing a1, the controller 40 activates the reticle stage driving motor 19 and the wafer stage driving motor 29 to drive the reticle stage 18 and the wafer stage 27 in synchronization at a predetermined speed ratio (a). . As for the drive control state of wafer stage 27, reticle stage 18 and wafer stage 27 are synchronously driven at a predetermined speed ratio as described above, and therefore illustration and description thereof are omitted.

The driving speed of the reticle stage 18 reaches a steady state (speed Vn), and the pattern P
The leading edge of A and the leading edge of the predetermined exposure area on the wafer 25 approach the optical axis of the projection optical system 23. At this time, the control unit 40 issues an oscillation start command to the laser controller LC (b), and in response thereto, the laser beam is emitted from the laser oscillator EL at a normal pulse emission interval (c). Thus, the scan exposure operation starts. At timing c1, the control unit 40 detects that the trailing edge of the pattern PA and the trailing edge of the predetermined exposure area on the wafer 25 approach the optical axis of the projection optical system 23 by detecting means (not shown). Then, an oscillation stop command is issued to the laser controller LC (b). This causes the laser oscillator EL to stop emitting laser light. Next, the control unit 40 controls the reticle stage driving motor 19 and the wafer stage driving motor 29 to decelerate and stop. The control unit 40 ends the scan exposure operation for one chip by the above operation.

The control unit 40 drives the wafer stage 27 in the X-axis and / or Y-axis directions according to a predetermined exposure order determination algorithm to guide the exposure area for the next exposure operation to the exposure preparation position (this operation is described below). It is not shown in FIG. 10).

At the timing a2, the control unit 40 starts the reticle stage driving motor 19 and the wafer stage driving motor 29, and the above-mentioned timings a1 to b
Scan exposure is started in the same manner as in the operation 1. At timing c2 during the scanning exposure operation, the control unit 40
Door switch D issued in conjunction with the opening of the door
Upon receiving the signal from Sw, it issues an oscillation stop command to the laser controller LC. Upon receiving the oscillation stop command, the laser controller LC stops the oscillation operation of the laser oscillator EL at the timing d2. At timing e2, the control unit 40 detects that the trailing edge of the pattern PA and the trailing edge of the predetermined exposure area on the wafer 25 approach the optical axis of the projection optical system 23 by detecting means (not shown). Then, the reticle stage driving motor 19 and the wafer stage driving motor 29 are decelerated and stopped. The reason why the control unit 40 stops emitting laser light when receiving a signal from the door switch DSw during the scan exposure operation is as follows. That is, if the pulse emission interval of the laser light is increased during the scan exposure operation, the wafer 25 cannot obtain a uniform exposure amount unless the moving speed of the reticle stage 18 and the wafer stage 27 is reduced accordingly. On the other hand, as described in the first embodiment, when the control unit 40 detects that the door is opened and extends the pulse emission interval of the laser beam, the controller 40 moves at a constant speed in conjunction with this. It is difficult to lower reticle stage 18 and wafer stage 25 in a very short time. Therefore, as described above, the emission of the laser beam is stopped to stop the exposure. At this time, the control unit 40 transfers the defective shot information relating to the chip whose exposure has been interrupted halfway to a host computer (not shown) that integrally controls the plurality of exposure apparatuses at timing f2 in FIG. The host computer (not shown) manages this defective shot information in a subsequent process.

Next, the scan exposure operation performed when the door is open will be described. Also in this example, by increasing the pulse emission interval of the laser light,
The laser light leaking from the opening of the opened door is prevented from passing through the AEL. At this time, it is necessary to give a constant exposure amount to the exposure region of the wafer 25 irrespective of the pulse emission interval of the laser light, so the moving speed of the reticle stage 16 is set to Vs lower than the normal speed Vn. Control. Hereinafter, this is referred to as low-speed scan exposure. The operation of the low-speed scan exposure is shown at timings a3 to d3 in FIG.

The controller 40 starts the reticle stage driving motor 19 and the wafer stage driving motor 29 at timing a3 (a). The driving speed of the reticle stage 18 reaches a steady state (speed Vs), and the leading edge of the pattern PA and the wafer 2 at timing b3.
And the leading edge of the predetermined exposure area on the projection optical system 23
Approaching the optical axis. At this time, the control unit 40 issues an oscillation command to the laser controller LC so as to oscillate with the pulse emission interval widened (b). In response, the laser beam is emitted from the laser oscillator EL at a time interval wider than the normal pulse emission interval as shown in FIG. 11C, and low-speed scan exposure starts.

When the door that has been opened at timing c3 during the low-speed scan exposure is closed, the control unit 40
Detects that the signal output from the door switch DSw has changed, but continues the low-speed scan exposure operation. At timing d3, the control unit 40 detects that the trailing edge of the pattern PA and the trailing edge of the predetermined exposure area on the wafer 25 are approaching the optical axis of the projection optical system 23 by a detection unit (not shown). , Laser controller LC
(B). Next, the control unit 4
0 decelerates and stops the reticle stage driving motor 19 and wafer stage driving motor 29.

As described with reference to the timings a3 to d3, even if the control unit 40 detects that the opened door is closed during the low-speed scan exposure, the control unit 40 continues the low-speed scan exposure operation, and To complete. As a result, there is no waste because the chip during the low-speed scanning exposure does not become defective.

After that, the control section 40 drives the wafer stage 27 in the X-axis and / or Y-axis directions according to a predetermined algorithm and a predetermined exposure order determining algorithm to set an exposure area (chip to be exposed) for the next exposure operation. Guide to the exposure preparation position.

Since the door is closed at the timing a4, the control unit 40 sets the timings a1 to c in FIG.
1, a normal scan exposure operation is performed.

Incidentally, the timings a2 to f2 in FIG.
In the description of the scan exposure operation in the above, the example in which the control unit 40 issues a command to stop oscillation to the laser controller LC when detecting that the door is opened during the scan exposure operation has been described. In this case, the laser beam leaking from the opening of the opened door does not exceed the AEL, but the chip during the scan exposure becomes defective. Therefore, an automatic lock mechanism (not shown) may be provided on the door, and the control unit 40 controls the automatic lock mechanism to lock the door during scan exposure. Then, the control unit 40 unlocks the door before starting the next scan exposure,
By performing low-speed scan exposure, occurrence of chip failure can be prevented.

In the description of the second embodiment, when the scan exposure operation for one chip is completed,
Alternatively, when the door is opened during the scanning exposure operation, the control unit 40 issues an oscillation stop command to the laser controller LC. Instead, a shutter (not shown) is provided in the optical path of the excimer laser light. It may be inserted to block excimer laser light.

In the above description of the first and second embodiments, an example has been described in which a laser oscillator that emits pulses of an excimer laser is used as a light source for illumination.
Other pulsed light sources may be used. For example, a light source that emits soft X-rays in a pulsed manner may be used.

Although the example in which the pulse light emission interval is extended to reduce the amount of illumination has been described, the peak illuminance at the time of pulse light emission may be reduced.

Further, an example has been described in which the amount of illumination is reduced by using the dimming plate ND. However, as the dimming plate, a so-called ND filter may be used, or a grid-like plate having a predetermined aperture area ratio may be used. Is also good.

In the above description of the embodiment, the present invention is applied to a projection exposure apparatus, but the present invention is not limited to this. That is, the present invention is also applicable to other devices that use a light source for which an AEL is determined or a light source that adversely affects the eyes when viewed, such as ultraviolet light.

In the correspondence between the above-described embodiment and the claims, the laser oscillator EL is a pulsed light source, the door switch DSw is a detection unit, the control unit 40 is a dimming unit and an image processing unit, and the dimming plate is The ND constitutes a dimming member, and the integrated exposure monitor 10 constitutes an illuminance detection integrating means.

[0081]

(1) According to the first aspect of the present invention, the amount of illumination is reduced when it is detected that the lid mounted on the housing of the projection exposure apparatus has been opened, thereby reducing the amount of illumination. Laser light leaking from the open part of the laser does not exceed the exposure radiation limit (AEL). Further, the operation of the projection exposure apparatus can be continued in a state where the illumination light amount is reduced, and the operation rate is not significantly reduced. (2) According to the second aspect of the invention, the light emission period of the pulsed light source is made longer than the light emission period before the lid is opened, so that the amount of illumination light is reduced. Even in a projection exposure apparatus using a light source in which it is difficult to change the peak illuminance of light, the amount of illumination light can be easily reduced. (3) According to the third aspect of the present invention, the amount of illumination is reduced by inserting a dimming member in the optical path of the light emitted from the pulsed light source. Even in a projection exposure apparatus using a light source in which it is difficult to change the peak illuminance of pulsed light, the amount of illumination light can be easily reduced. (4) According to the invention described in claim 4, when it is detected that the lid is closed while sequentially performing projection exposure in a state where the illumination light amount is reduced, the projection exposure at that time is terminated. Since the dimming of the illumination light can be released after
The occurrence of defective shots can be suppressed by a scanning exposure apparatus or the like. (5) According to the invention described in claim 5, the integrated illuminance of the illumination light is detected, and the projection exposure is performed until the integrated illuminance in each shot area reaches a predetermined value, and the exposure amount in each shot area is kept constant. , A stable exposure operation can be continued even when the amount of illumination light is reduced. (6) According to the invention of claim 6, when the illumination light amount is not reduced, an image is input regardless of the light emission timing of the pulsed light source, while when the illumination light amount is reduced, the light emission timing of the pulsed light source is reduced. , A clear image can be input regardless of the length of the light emission interval of the pulsed light source.
As a result, highly accurate image processing can be performed. (7) According to the invention described in claim 7, when the lid installed on the housing is detected to be opened, the amount of illumination by the pulsed light source is reduced to thereby open the lid. The pulse emission light leaking from the
L). In addition, the operation of the devices in the housing can be continued in a state where the illumination light amount is reduced, and the operation rate is not significantly reduced. (8) According to the invention as set forth in claim 8, since the light emission period of the pulsed light source is made longer than the light emission period before the lid is opened, the amount of illumination light is reduced. Even if the installed device uses a light source in which it is difficult to change the peak illuminance of the pulsed light, the amount of illumination light can be easily reduced. (9) According to the ninth aspect of the present invention, the amount of illumination is reduced by inserting a dimming member in the optical path of the light emitted from the pulsed light source. Even if the device provided in the housing uses a light source in which it is difficult to change the peak illuminance of the pulsed light, the amount of illumination light can be easily reduced.

[Brief description of the drawings]

FIG. 1 is a view showing a schematic appearance of a projection exposure apparatus to which the present invention is applied.

FIG. 2 is a diagram showing a schematic configuration of a projection exposure apparatus according to the first embodiment.

FIG. 3 is a diagram showing a state where the wafer stage shown in FIG. 2 moves in the + X direction and performs baseline measurement.

FIG. 4 is an enlarged partial sectional view showing the vicinity of a lower portion of the projection optical system shown in FIG. 3;

FIG. 5 is a view showing an image captured by the CCD camera shown in FIG. 3;

FIG. 6 is a diagram showing an image captured by an imaging device built in the off-axis microscope shown in FIG. 3;

FIG. 7 is a view showing that the wafer stage shown in FIG. 2 has moved in the + X direction and is in a state of performing autofocus calibration.

FIG. 8 is an enlarged partial cross-sectional view showing the vicinity of the oblique incidence AF system shown in FIG. 7;

FIG. 9 is a view showing an exposure sequence in the projection exposure apparatus (batch exposure type projection exposure apparatus) according to the first embodiment.

FIG. 10 is a diagram showing a schematic configuration of a projection exposure apparatus according to a second embodiment.

FIG. 11 is a view showing an exposure sequence in a projection exposure apparatus (scan exposure type projection exposure apparatus) according to a second embodiment.

[Explanation of symbols]

 Reference Signs List 6 fly-eye lens 10 integrated exposure monitor 10A light quantity monitor 11, 13 relay lens 12 field stop 12A variable field stop 14 mirror 15 condenser lens 16 reticle 18 reticle stage 23 projection optical system 25 wafer 27 wafer stage 28 reference plate 40 control unit 100 chamber LC Laser Controller EL Laser Oscillator ND Darkening Plate TP Turret Plate RM, RM1 Reticle Mark PA Pattern FM, FM1 Reference Mark LG Light Guide DSw Door Switch DM Maintenance Door DR Reticle Replacement Door DW Wafer Replacement Door

Claims (9)

[Claims] An illumination optical system for illuminating an original on which a predetermined pattern is formed with light emitted from a pulsed light source; and projecting the pattern of the original illuminated by the illumination optical system onto a photosensitive substrate. In a projection exposure apparatus comprising: a projection optical system; a housing that covers the illumination optical system and the projection optical system; and a lid that is openably and closably installed in the housing, a detection unit that detects opening and closing of the lid. And a dimming means for reducing the amount of illumination by the illumination optical system when the detecting means detects that the lid is opened. 2. The projection exposure apparatus according to claim 1, wherein the dimming unit determines a light emission cycle of the pulse emission by the pulse emission light source before the detection unit detects that the lid is opened. A projection exposure apparatus characterized in that the illumination light amount is reduced by making it longer than a light emission cycle. 3. The projection exposure apparatus according to claim 1, wherein the dimming unit reduces the amount of illumination by a dimming member inserted into an optical path of light emitted from the pulsed light source. Projection exposure equipment. 4. The projection exposure apparatus according to claim 1, wherein the detecting unit detects that the lid is opened, and the amount of illumination is reduced by the dimming unit. When the pattern of the original is sequentially projected and exposed on the photosensitive substrate in the state, when the detecting means detects that the lid is closed, it is determined that the detecting means has closed the lid. A projection exposure apparatus, wherein the reduction of the illumination light amount by the dimming means can be canceled after the completion of the projection exposure in the shot area where the projection exposure is performed at the time of detection. 5. The projection exposure apparatus according to claim 1, wherein an illuminance of illumination light from the illumination optical system is detected and integrated,
Even after the amount of illumination is reduced by the dimming unit, projection exposure is performed until the integrated illuminance in each shot area on the exposure substrate reaches a predetermined value. A projection exposure apparatus further comprising an illuminance detection integration means for controlling the exposure amount in each of the shot areas to be constant. 6. The projection exposure apparatus according to claim 2, further comprising image processing means for inputting an image obtained by photographing an object illuminated by the pulsed light source and performing predetermined processing. The image processing means inputs the image irrespective of the light emission timing of the pulsed light source when the illumination light amount is not reduced, and emits the light emission timing of the pulsed light source when the illumination light amount is reduced. A projection exposure apparatus for inputting the image in synchronization with the projection exposure. 7. A pulse light emission method for emitting pulse light from the pulse light source in a state where an optical system for guiding light emitted from the pulse light source is covered with a housing having a lid that can be opened and closed. The pulse light emission method according to any one of claims 1 to 3, wherein the light amount from the pulse light source is reduced when it is detected that the lid is opened while the pulse light source is emitting pulses. 8. The pulse light emission method according to claim 7, wherein the light emission of the pulse light emission by the pulse light source is compared with a pulse light emission cycle before detecting that the lid is opened to reduce the light amount. A pulse emission method characterized by increasing the period. 9. The pulse light emitting method according to claim 7, wherein a dimming member is inserted into an optical path of light emitted from the pulse light source to reduce the exposure amount.