JPH06132191A - Projection exposure device - Google Patents

Abstract

PURPOSE:To decrease the illuminance irreguralities on a light sensitive substrate, in an projection exposure device for performing the exposure by a slit-scan exposure system by using a pulse-lighting type light source. CONSTITUTION:The pattern image of a reticle is projected on the arc-shaped exposed region 46P on a wafer 15. A wafer 15 is scanned in the direction of DW with respect to the exposed region 46P in synchronization with the scanning of the reticle on the lighting area. When the distance, wherein a wafer 15 is moved in the light-emitting interval (1 cycle) of the pulse laser light, is made to be DELTAL, the width beta.L of the exposing region 46P in the direction of DW is set at the integer times of the distance DELTAL.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus used, for example, in manufacturing a semiconductor integrated circuit, a liquid crystal display element or the like in a lithographic process, and more particularly to a so-called slit scan exposure method using a pulsed light source. The present invention relates to a projection exposure apparatus that performs exposure.

[0002]

2. Description of the Related Art When a semiconductor device, a liquid crystal display device, or the like is manufactured by a lithography process, a pattern image of a photomask or reticle (hereinafter referred to as "reticle") is exposed under exposure light through a projection optical system. A projection exposure apparatus that projects on a photosensitive substrate is used. In such a projection exposure apparatus, it is required to further improve the resolution.
One method for improving the resolution is to shorten the wavelength of exposure light. Among the light sources currently in practical use, the one with a relatively short wavelength is an ArF excimer laser (wavelength: 193n
m), an excimer laser such as a KrF excimer laser (wavelength: 248 nm), and a metal vapor laser. However, since the excimer laser light source and the metal vapor laser light source are of a pulse emission type (pulse oscillation type), it is necessary to consider the use differently from the case of a continuous emission light source such as a mercury lamp.

FIG. 7 shows a projection exposure apparatus equipped with a conventional pulse emission type laser light source. In FIG. 7, a laser beam LB emitted from a pulse emission type laser light source 1 is beamed by a beam expander 2. The diameter is enlarged and the light enters the first fly-eye lens 3. Secondary light sources are formed on the rear focal plane of the first fly-eye lens 3 in accordance with the number of lens elements, and the laser light diverging from these secondary light sources passes through the deflection mirror 4 and the condenser lens 5, respectively, and then into the second fly. It is incident on the eye lens 6.
Secondary light sources are also formed on the rear focal plane of the second fly-eye lens 6 in accordance with the number of lens elements, and the laser light diverging from these secondary light sources passes through the first relay lens 7 and the deflection mirror 8 respectively. It is focused on the field stop 9. The laser light focused on the aperture of the field stop 9 is a combination of a large number of laser lights emitted from the respective lens elements of the fly-eye lens 6 and having incoherent mutual illuminance distributions. Is.

The pulsed laser light IL as the exposure light that has passed through the aperture of the field stop 9 passes through the second relay lens 10 and the condenser lens 11 and has a uniform illuminance.
Illuminate 2. The arrangement surface of the field stop 9 is conjugate with the pattern forming surface of the reticle 12, and the illumination area of the reticle 12 with the pulsed laser light IL is set by the shape of the opening of the field stop 9. Under the pulsed laser light IL,
An image of the pattern of the reticle 12 is imaged and projected on the wafer 15 on the wafer stage 14 via the projection optical system 13.

[0005]

As described above, in a conventional projection exposure apparatus using a pulsed light emitting laser light source, the images of the chip patterns on the pattern formation surface of the reticle 12 are collectively displayed on the wafer 15. The batch exposure method of exposing was the mainstream. Therefore, the projection optical system 13 also has an exposure field for exposing the image of the chip pattern at one time. However, in recent years, there is an increasing demand not only for shortening the wavelength of exposure light, but also for increasing the field to expose an image of a larger chip pattern on the reticle 12 onto the wafer 15.

In order to meet the demand for a large field, a so-called slit scan exposure system is effective in which the reticle 12 and the wafer 15 are scanned synchronously with, for example, a slit-shaped illumination area set by the field stop 9. . Thereby, an image of a pattern wider than the illuminated area on the reticle 12 can be exposed on the wafer 15. However, if the slit scan exposure method is simply applied to a projection exposure apparatus that uses a pulsed laser light source, the number of pulsed laser light ILs that are exposed varies depending on the exposure position on the wafer 15, and uneven illumination occurs. There was an inconvenience to do.

Further, when the wavelength of the exposure light is shortened and laser light in the vacuum ultraviolet region is used, for example, since the transmittance characteristic of the ordinary refraction element is deteriorated, it is desirable in the refraction projection system composed of only the refraction element. It becomes difficult to obtain the imaging characteristics of. Therefore, when the exposure light has a short wavelength, a catadioptric projection system including a reflective element that has no chromatic aberration and little absorption of light is advantageous. However, in the reflective element, since the good image range is an arcuate region that is away from the optical axis by a predetermined amount, the slit scan exposure method is particularly effective in order to cope with a large field. However, when the slit scan exposure method is applied to the projection exposure apparatus including the pulsed light source and the catadioptric projection system, as in the case of the projection exposure apparatus including the refraction projection system,
Due to the relationship between the scanning of the wafer and the timing of pulsed light emission of the laser light source, the illuminance unevenness of the pulsed laser light occurs depending on the exposure position on the wafer.

In view of the above problems, an object of the present invention is to reduce unevenness of illuminance on a photosensitive substrate in a projection exposure apparatus which performs exposure by a slit scan exposure system using a pulse emission type light source.

[0009]

A projection exposure apparatus according to the present invention, for example, as shown in FIGS. 1, 2 and 4 (a), uses a pulse light source (16) for emitting a pulse of exposure light and the exposure light. An illumination optical system (17, 1) for irradiating the mask (12)
8 and 19) and the field diaphragms (42A, 42B, 44A, 42A, 42B, 44A, which set the illumination area of the exposure light for the mask (12).
44B), a projection optical system (27 to 33) for projecting an image of the pattern of the mask (12) onto the photosensitive substrate (15) under the exposure light, the mask (12) and the photosensitive substrate (1).
Relative moving means (24, 2) for moving 5) relative to the field stop in a direction perpendicular to the optical axis of the projection optical system.
5, 38), and a mask (12) and a photosensitive substrate (15) for an illumination area set by the field stop.
In a projection exposure apparatus that projects an image of a pattern of an area wider than the illumination area set by the field stop of the mask (12) on the photosensitive substrate (15) by relatively scanning the field stop. Mask to be set (1
2) The projected image (46) on the photosensitive substrate (15) in the illuminated area on
The width β · L of P) in the relative scanning direction is set to the photosensitive substrate (1) during one cycle of pulse emission of the pulse light source (16).
5) is a projected image (46P) of the illuminated area on the mask (12)
Is set to an integral multiple of the distance ΔL that moves relative to.

[0010]

According to the present invention, for example, in FIG. 4A, the width β in the relative scanning direction (DW direction) of the projected image (46P) on the photosensitive substrate (15) in the illumination region on the mask.・
It is assumed that L is n times (n is an integer of 1 or more) the distance ΔL that the photosensitive substrate (15) moves in the RS direction during one cycle of pulsed light emission of the pulsed light source (16). That is, the following equation is established. β ・ L = n ・ ΔL

In this case, the light source (1
6) is the point P1 which is the exposure position at the edge of the projected image (46P) at the time of pulse emission, and shows the amount of energy applied to each exposure position on the photosensitive substrate (15) by one pulse emission. Let ΔE. Therefore, at the time of pulsed light emission, the point at the edge of the projected image (46P) is irradiated with energy of ΔE / 2. Then, the amount of energy E _P1 applied to the point P1 is as follows. E _P1 = 2 · ΔE / 2 + (n-1) · ΔE = n · ΔE

Further, at the point P2 slightly inside the edge portion of the projected image (46P) during pulsed light emission, pulsed light emission is performed n times while being in the projected image (46P). The amount of energy applied to the point P2 is also n · ΔE, and the amount of energy applied to all exposure positions on the photosensitive substrate (15) is n · ΔE, so that there is no unevenness in illuminance.

On the other hand, as shown in FIG.
The width β · L1 in the relative scanning direction (DW direction) of the projected image (46P) on the photosensitive substrate (15) in the illumination region is such that the photosensitive substrate (1
5) of the distance ΔL1 in which the DW direction moves, for example, 3.
It is supposed to be 5 times. In this case, when the light source (16) emits pulses on the photosensitive substrate (15), the projected image (46
If the exposure position at the edge of P) is point Q1, point Q1
The amount of energy E _Q1 applied to ₁ is 3.5 · ΔE.

The amount of energy E _Q2 applied to a point Q2 slightly inside the edge portion of the projected image (46P) during pulse emission is 4 · ΔE, and the edge portion of the projected image (46P) during pulse emission. The amount of energy E _Q3 radiated to the point Q3, which is slightly outside of, is 3 · ΔE. Therefore, the amount of energy irradiated according to the exposure position on the photosensitive substrate (15) varies from 3 · ΔE to 4 · ΔE, which causes uneven illuminance.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the projection exposure apparatus according to the present invention will be described below with reference to FIGS. In the present embodiment, the present invention is applied to a slit scan exposure type projection exposure apparatus equipped with a pulsed laser light source and a catadioptric projection system. FIG. 1 shows the entire configuration of the projection exposure apparatus of the present embodiment. In FIG. 1, a laser beam LB emitted from a pulse laser light source 16 such as an excimer laser light source is a beam expander, an optical integrator, an aperture stop, The light enters the beam shaping optical system 17 including a relay lens system and a variable field stop. The pulse laser light IL as the exposure light emitted from the beam shaping optical system 17 passes through the mirror 18 and the condenser lens 19 and illuminates the reticle 12 with a uniform illuminance.

The reticle 12 is held on the reticle stage 20, and a movable mirror 21 is attached to one end of the reticle stage 20 in the Z direction (vertical direction in the plane of FIG. 1). The reticle stage 20 and the movable mirror 21 are guided by a guide 22. It is supported so as to be able to move at a constant speed in the Z direction. The reticle stage 20 is connected with a drive device 24 for performing movement in the Z direction and minute rotation for yawing correction. Further, the laser beam from the laser interferometer 23 fixed to the guide 22 is reflected by the moving mirror 21, and the laser interferometer 23 constantly measures the Z direction position and yawing amount of the reticle 12, and the measurement data S1 is supplied to the main control system 25. The main control system 25 controls the operation of the reticle 12 via the drive unit 24, controls the shape of the aperture of the variable field stop in the beam shaping optical system 17, and the laser light source control unit 26.
The light emitting operation of the pulsed laser light source 16 is controlled via.

The pulsed laser light IL that has passed through the pattern of the reticle 12 is guided to the first concave mirror 28 through the first lens group 27, and is reflected there to obtain a predetermined reduction magnification. The pulsed laser light reflected by the first concave mirror 28 passes through the second lens group 29 and the plane reflecting mirror 3 for bending the optical path.
The light is reflected at 0 and enters the second concave mirror 32 through the negative lens 31, and the reflection here gives a magnification slightly larger than equal magnification. The pulsed laser light reflected by the second concave mirror 32 passes through the negative lens 31, is given a reduction magnification by the third lens group 33, and enters the wafer 15. Wafer 15
The pattern of the illumination area of the reticle 12 is transferred onto the top of the reticle 12 in a reduced size of 1/4. A projection optical system is configured by the first lens group 27 to the third lens group 33.

The wafer 15 is held on a wafer holder 34 which is capable of minute rotation, and the wafer holder 34 is fixed on a wafer stage 35. Wafer stage 35
Is an XY stage for positioning the wafer 15 in a two-dimensional plane consisting of an X direction which is a left-right direction in the plane of FIG. 1 and a Y direction perpendicular to the plane of FIG. 1, and a Z stage which positions the wafer 15 in the Z direction. Etc. A movable mirror 36 for reflecting the laser beam from the laser interferometer 37 is fixed on the wafer stage 35, and the laser interferometer 37 constantly measures the position and yawing amount of the wafer 15 in the XY plane. Is the main control system 25
Is being supplied to. The main control system 25 controls the operation of the wafer stage 35 via the drive device 38.

FIG. 2 shows the components in the beam shaping optical system 17 of FIG. 1, and the rotary plate 39 is a beam shaping optical system 1 of FIG.
The laser beam LB of No. 7 is arranged at the incident portion. The ND filter plates 40A, 40B, 4 in which the transmittance for the laser beam LB changes stepwise in the passage region of the laser beam LB on the peripheral portion of the rotating plate 39.
0C, ... Are mounted, and the main control system 25 adjusts the rotation angle of the rotary plate 39 via the drive unit 41, so that FIG.
It is possible to set the illuminance of the pulsed laser light IL applied to the wafer 15 in a desired range. Although not shown, for example, an irradiation amount monitor for monitoring the illuminance of the pulsed laser light IL is arranged on the wafer stage 35 in FIG.

In FIG. 2, two long blades 42 are shown.
A variable field stop is constituted by A, 42B and two short blades 44A, 44B. These blades 4
An arc-shaped opening 46Q surrounded by 2A, 42B and 44A, 44B corresponds to the illumination area on the reticle 12. In addition, the main control system 25 uses the drive device 43 to drive the blade 42
By adjusting the distance between A and 42B and adjusting the distance between the blades 44A and 44B via the drive device 45,
The size of the opening 46Q can be adjusted. The area of the projected image of the opening 46Q on the pattern formation surface of the reticle 12 is an arcuate illumination area on the reticle 12.

FIG. 3 shows an illuminated area 46 on the reticle 12, which is comprised of two parallel circles with an interval L and an interval M.
Is an arcuate region surrounded by two parallel straight lines. That is, the width of the illumination area 46 in the longitudinal direction is M, and the width of the illumination area 46 in the narrow direction (DR direction) perpendicular to the longitudinal direction is L anywhere. By scanning the reticle 12 in the narrow DR direction, the pulsed laser light in the illumination area 46 sequentially illuminates a wider pattern area on the reticle 12. The DR direction in FIG. 3 is the same as the −Z direction in FIG.

When performing slit scan exposure in the present embodiment, in FIG. 1, the arc-shaped illumination area 46 on the reticle 12 is illuminated by the pulsed laser light IL, and the drive device 24 and the reticle stage 20 are used. Reticle 1
2 is a constant velocity V in the -Z direction (that is, the DR direction in FIG. 3).
Scan with. The exposure area 46P on the wafer 15 which is conjugate with the illumination area 46 is provided with the reticle 12 in the illumination area 46.
The image of the pattern is image-projected. Further, assuming that the projection magnification of the projection optical system including the first lens group 27 to the third lens group 33 from the reticle 12 to the wafer 15 is β (β = 1/4 in this example), the driving device 38 and the wafer stage 3 are used.
The wafer 15 is scanned in the X direction at a constant speed β · V via the scanning line 5.

When scanning the reticle 12 and the wafer 15, for example, when the predetermined alignment mark on the reticle 12 and the predetermined alignment mark on the wafer 15 match, the measurement value of the laser interferometer 23 and the laser interference. The difference between the total of 37 measured values is stored as a reference value,
The operations of the driving devices 24 and 38 are controlled so that the difference between the measurement value of the laser interferometer 23 and the measurement value of the laser interferometer 37 becomes the reference value stored in advance. Therefore, the reticle 12 and the wafer 15 are always stationary in a predetermined relationship with each other, and are scanned in a narrower direction with respect to the illumination area 46 and the exposure area 46P, respectively.

Next, the condition of the width of the arc-shaped exposure area 46P in the narrow width direction, that is, the width in the relative scanning direction will be described. FIG. 4A shows an arc-shaped exposure region 46P on the wafer 15 of this embodiment. In FIG. 4A, the direction in which the wafer 15 is scanned with respect to the exposure region 46P is the DW direction (this is Also in the X direction), since the projection magnification of the projection optical system is β, the width of the exposure region 46P in the DW direction is β · L. In addition, the pulse laser light source 16 of FIG.
The pulse scanning period (that is, the reciprocal of the emission frequency) is T, and the distance over which the wafer 15 is scanned in the DW direction during one period T during slit scan exposure is ΔL.
And In this case, D, which is the scanning direction of the exposure area 46P,
The width β · L in the W direction is set to an integral multiple of the distance ΔL. Further, since the speed of the wafer 15 in the DW direction is β · V,
The distance ΔL is T · β · V. That is, the following formula is established with n being an integer of 1 or more.

[Equation 1] β · L = n · ΔL = n · T · β · V

FIG. 4A shows the case of β · L = 3 · ΔL. At this time, for example, the wafer 1 existing at the edge portion of the exposure region 46P at the time when pulsed light emission occurs
The point P1 on 5 is sequentially scanned with the positions P1A, P1B, and P1C at the time of the subsequent pulse emission. Further, assuming that the exposure energy applied to the exposure point inside the exposure region 46P by one pulse emission is ΔE, the exposure point P1 has 3 ·.
Exposure energy of ΔE (= ΔE / 2 + 2 · ΔE + ΔE / 2) is applied. Further, for example, the exposure point P2 on the wafer 15 existing inside the edge portion of the exposure region 46P at the time of pulse emission is sequentially scanned to the positions P2A, P2B, P2C at the subsequent pulse emission. And
The exposure point P2 is irradiated with exposure energy of 3 · ΔE. Therefore, according to this example, the exposure area 4 on the wafer 15 is
The same exposure energy of n · ΔE is applied to all exposure points scanned by 6P. Therefore, there is no unevenness in illuminance, and the imaging characteristics on the wafer 15 are improved.
However, since there is a variation in the exposure energy for each pulse emission, the influence of this variation will be described later.

On the other hand, for example, as shown in FIG. 4B, the width of the exposure region 46P in the DW direction which is the scanning direction is β · L1, and this width β · L1 is pulsed by the pulse laser light source 16. Wafer 15 is DW during one cycle T of
The distance ΔL scanned in the direction is 3.5 times. In this case, the exposure point Q1 on the wafer 15 existing at the edge portion of the exposure region 46P at the time when the pulse emission is generated is 3.5.
The exposure point Q2 on the wafer 15 existing inside the edge portion of the exposure region 46P at the time when the exposure energy of ΔE is irradiated and the pulse light emission is irradiated with the exposure energy of 4 · ΔE and the pulse light emission occurs. Exposure area 46P
Exposure point Q3 on the wafer 15 existing outside the edge of
Is irradiated with exposure energy of 3 · ΔE. Therefore, it can be seen that the illuminance unevenness occurs.

Next, the operation in the case of performing exposure by the slit scan exposure system in this embodiment will be described. First, in FIG. 1, the scanning speed β · V of the wafer 15 in the X direction is
The average illuminance P of the pulsed laser light IL per pulse on the wafer 15, the sensitivity S of the resist applied on the wafer 15, and the illuminance variation ΔP _i (i = 1, 1) for each pulsed emission of the pulsed laser light IL. 2, ...). Further, as described above, in this example, each exposure point on the wafer 15 is irradiated with the pulsed laser light IL n times, so that the integrated illuminance PT of each exposure point is as follows. However, Σ means the sum of 1 to n regarding the subscript i.

(2) PT = Σ (P + ΔP _i )

From this, it is understood that the dispersion of the integrated illuminance PT, that is, the illuminance unevenness decreases as the number n of times the pulsed laser light IL is irradiated increases. Therefore, depending on how much the variation in the integrated illuminance PT is suppressed, the number of irradiations of the pulsed laser light IL (the number of pulses) n
The value of is determined. For example, when n is set to 20, the uneven illuminance is suppressed to about 0.05%. Also, the wafer 12
Since the integrated illuminance PT at each exposure point above is approximately n · P,
The resist sensitivity S determines how much the power of the laser beam LB emitted from the pulsed laser light source 16 in FIG. 1 should be set. In order to set the power of the laser beam LB of the pulse laser light source 16 to this determined level, as shown in FIG. 2, the main control system 25
Is a rotating plate 3 equipped with ND filter plates of various transmittances.
Set the angle of 9 to the corresponding angle.

Next, as shown in FIG. 3, the drive speed of the reticle 12 and the wafer 15 is set in correspondence with the width L of the illumination area 46 on the reticle 12 in the DR direction which is the scanning direction. First, in FIG. 4A, the width of the exposure region 46P on the wafer 15 in the DW direction is β · L, and the scanning speed of the wafer 15 in the DW direction is β · V. Further, the distance that the wafer 15 moves in the direction DW during the period T of pulsed light emission of the pulsed laser light source 16 of FIG. 1 is T.beta..multidot.V.
Therefore, the same relationship as in (Equation 1) holds.

[Formula 3] β · L = n · ΔL = n · T · β · V

As a result, the scanning speed V of the reticle 12 in the scanning direction is as follows. Using this scanning speed V, the scanning speed of the wafer 15 is set to β · V.

[Expression 4] V = L / (n · T) Further, since the scanning speed V of the reticle 12 has an upper limit V _max due to the configuration of the mechanical section, from (Expression 4), V ≦ V _max The value of the width L of the illumination area 46 on the reticle 12 in the scanning direction is adjusted. For that purpose, the interval between the blades 42A and 42B in FIG. 2 may be adjusted. After that, when the image of the pattern of the reticle 12 is exposed on the wafer 15 by the slit scan exposure method, the illuminance by the pulse laser beam IL becomes almost the same level in all the exposure areas on the wafer 15, and good transfer characteristics are obtained. .

In the above description, the pulse emission interval (cycle T) is constant, but for example, the scanning speed V is V
_The cycle T may be adjusted with _max and width L kept at values corresponding to V _max . This is performed by the controller 26 based on a command from the main control system 25. Also,
When the interval (L) between the blades 42A and 42B in FIG. 2 is fixed, the pulse emission period T of the pulse laser light source 16 in FIG. 1 based on the predetermined value of n, and / Alternatively, the scanning speed V of the reticle 12 may be adjusted. In short, the interval L, the period T, and the scanning speed V are set so that the projected image 46P and the wafer 15 are pulse-emitted only an integer number of times during the relative movement of the projected image 46P in the scanning direction (β · L). At least one of them should be adjusted. At this time, the value of n is the minimum number of pulses required to achieve the desired illuminance uniformity required on the wafer (as described above, it is uniquely determined according to the variation in the energy amount between the pulses. ) Is desirable.
A method of determining the required number of pulses is disclosed in, for example, Japanese Patent Laid-Open No.
It is disclosed in Japanese Patent Publication No. 179357. Further, when the power of the laser beam changes due to the change of the pulse emission period T, it is necessary to readjust the power of the laser beam by adjusting the angle of the rotary plate 39 in FIG.

Further, in this embodiment, an integer n of 1 or more is provided between the scanning speed V of the reticle 12, the period T of pulsed light emission, and the width L of the arc-shaped illumination area 46 on the reticle 12 in the scanning direction. It suffices if the relationship of (Equation 4) is used. Therefore, within the range that satisfies (Equation 4), the scanning speed V is a speed close to the optimum speed with little vibration, the pulse emission cycle T is a cycle close to the cycle in which the illuminance unevenness for each pulse is the smallest and the output is stable, The width L of the wafer 15
The width can be set to a width close to the optimum width in consideration of the leveling of the above. This makes it possible to maximize the performance of the projection exposure apparatus while keeping the illuminance unevenness on the wafer 15 to a minimum. That is, in this embodiment, the value of n is set to the number of pulses required to achieve the illuminance uniformity, and for example, when the throughput of the apparatus is emphasized, the scanning speed V is set to V _max , the cycle T and the width are set. It suffices to adjust at least one of L and L. When importance is attached to the image forming characteristics (distortion aberration, etc.) of the projection optical system, the width L is set to a width capable of obtaining an optimum image forming characteristic, and the period T and scanning are performed. At least one of the speed V may be adjusted.

Even if the method of this embodiment is applied, there is a possibility that unevenness in illuminance may actually occur due to the positional error of the wafer stage 35. Therefore, the position of the wafer stage 35 is monitored immediately before the pulsed light emission of the pulsed laser light source 16 and the position of the wafer stage 35 is corrected during the pulsed light emission, or the timing of the pulsed light emission is corrected by the position error of the stage. If this is the case, uneven illumination can be reduced.

Next, another embodiment of the present invention will be described with reference to FIGS. In this embodiment, the present invention is applied to a projection exposure apparatus using a refractive projection system as a projection optical system as shown in FIG. FIG. 5 shows the configuration in the vicinity of the projection optical system 13 of the projection exposure apparatus of this example, in which the pattern image of the reticle 12 is the wafer 1 under the pulsed laser light IL.
5 is exposed. The pulsed laser light IL illuminates a rectangular illumination area on the reticle 12, and the reticle 12 is scanned at a constant speed V in the X direction, which is the narrower direction of the illumination area. In synchronization with this, the projection magnification of the projection optical system 13 is set to β, and the wafer 15 is scanned in the −X direction at a speed β · V.

FIG. 6 shows a rectangular exposure area 48 on the wafer 15 of FIG. 5, in which the pattern of the reticle 12 is exposed. Scanning direction of exposure area 48 (-X
Direction) is β · L2, and the longitudinal width is β · M2
(M2> L2). In this case, assuming that the circular region 49 is the maximum exposure region of the projection optical system 13 of FIG. 5, the longitudinal width β · M2 of the exposure region 48 is the circular exposure region 4
It is almost equal to the diameter of 9. On the other hand, the exposure area 50 on the wafer 15 in the case of the normal batch exposure method is a substantially square area inscribed in the circular exposure area 49. Therefore, by scanning the wafer 15 in the −X direction with respect to the rectangular exposure area 48 to perform exposure, it is possible to perform exposure in a wider area than in the case of the collective exposure method.

If the emission period of the pulse laser beam IL is T, and the distance over which the wafer 15 is scanned in the −X direction during the period T is ΔL2, then the exposure region 48 in this example.
The width β · L2 in the −X direction, which is the scanning direction of, is set as follows using an integer n of 1 or more.

[Formula 5] β · L2 = n · ΔL2

The other structure is similar to that of the embodiment shown in FIG. As a result, each exposure point on the wafer 15 is irradiated with the pulsed laser light n times. Therefore, the illuminance by the pulsed laser light IL at all the exposure points on the wafer 15 is substantially the same, and the illuminance unevenness is minimized. It should be noted that the present invention is not limited to the above-described embodiments, and it goes without saying that various configurations can be adopted without departing from the gist of the present invention.

[0038]

According to the present invention, in a projection exposure apparatus which performs exposure by a slit scan exposure method using a pulsed light source, each point on a photosensitive substrate is exposed to the same number of times by pulsed light as exposure light. Since the light is exposed, there is an advantage that uneven illuminance on the photosensitive substrate can be reduced.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing optical elements in the beam shaping optical system 17 of FIG.

FIG. 3 is a plan view showing an arcuate illumination area on the reticle of the embodiment.

FIG. 4A is an enlarged plan view showing an arcuate exposure region on a wafer of the embodiment, and FIG. 4B is an enlarged plan view showing an arcuate exposure region when the present invention is not applied.

FIG. 5 is a schematic configuration diagram showing a main part of a projection exposure apparatus according to another embodiment of the present invention.

6 is an enlarged plan view showing a rectangular exposure area on the wafer in the embodiment of FIG.

FIG. 7 is a configuration diagram showing a projection exposure apparatus provided with a conventional pulsed light emission type laser light source.

[Explanation of symbols]

 12 reticle 15 wafer 16 pulse laser light source 17 beam shaping optical system 19 condenser lens 20 reticle stage 22 guide 23, 37 laser interferometer 24, 38 driver 25 main control system 28 first concave mirror 32 second concave mirror 35 wafer stage 46 reticle upper Illumination area 46P, 48 Exposure area on wafer

Claims (1)

[Claims] 1. A pulse light source for emitting exposure light in pulses,
An illumination optical system that irradiates the mask with the exposure light, a field stop that sets an illumination region of the exposure light with respect to the mask, and a projection that projects an image of the pattern of the mask onto the photosensitive substrate under the exposure light. An illumination system having an optical system and relative movement means for relatively moving the mask and the photosensitive substrate with respect to the field stop in a direction perpendicular to the optical axis of the projection optical system, the illumination being set by the field stop. Projection exposure for projecting an image of a pattern of a region wider than an illumination region set by the field stop of the mask onto the photosensitive substrate by relatively scanning the mask and the photosensitive substrate with respect to the region. In the apparatus, the width in the relative scanning direction of the projected image on the photosensitive substrate of the illumination area on the mask set by the field stop is set to 1 of the pulse emission of the pulse light source. The projection exposure apparatus in which the photosensitive substrate is characterized in that set to an integral multiple of the distance which moves relative to the projected image of the illuminated region on the mask during the period.