JP2001102291A - Method and device for exposure, and mask used for the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make errors in the exposure of a substrate small, when the pattern of a mask is transferred to the substrate by a scanning exposure system. SOLUTION: While a lit area 21R on a reticle R, having a pattern with an uneven transmissivity distribution in a non-scanning direction (X-direction) is lit with pulse ultraviolet light and an exposed region 21W on the wafer W is exposed to a pattern image in the lit region 21R via a projection optical system PL, scanning exposure is carried out by synchronously moving the reticle R and wafer W in the scanning direction (Y-direction). The transmissivity distribution of the projection optical system P varies gradually and unevenly in the non-scanning direction, because of the unevenness of the transmissivity distribution of the reticle R, so the non-scanning directional transmissivity distribution of light made incident on the exposed region 21W is measured each time a prescribed number of wafers are exposed, and the quantity of exposure of wafers W is controlled by using the transmissivity distribution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lithography process for manufacturing a device such as a semiconductor device, a liquid crystal display device, a plasma display or a thin-film magnetic head, and transfers a mask pattern onto a substrate via a projection optical system. The present invention relates to an exposure method and an exposure apparatus used for performing the exposure.
Further, the present invention relates to a mask that can be used when performing the exposure method.

[0002]

2. Description of the Related Art For example, in a batch exposure type exposure apparatus such as a stepper used for manufacturing a semiconductor element and a scanning exposure type exposure apparatus such as a step-and-scan method, a substrate to be exposed is It is necessary to keep the exposure of the photoresist on the wafer within an allowable range with respect to the proper exposure. Therefore, conventionally, an integrator sensor including a photoelectric detector that receives light branched from exposure light is arranged in an illumination optical system, and a relationship between a measured value of the integrator sensor and an exposure amount on a wafer is determined in advance. During the exposure, the exposure amount is controlled based on the measured value of the integrator sensor.

In these exposure apparatuses, the wavelength of the exposure light has been shortened in order to increase the resolution. At present, KrF excimer laser light having a wavelength of 248 nm is mainly used as the exposure light. Recently, the use of shorter wavelength 193 nm ArF excimer laser light has begun to be used, and the use of shorter wavelength F ₂ laser (wavelength 157 nm) is also being studied. However, the laser light from the far ultraviolet region to the vacuum ultraviolet region is pulsed light, and by using these ultraviolet pulsed light as exposure light, an optical member (glass material) constituting a projection optical system and these optical members are used. A phenomenon in which the transmittance of an optical film (such as an antireflection film) on the surface of a member fluctuates is known. Further, not only the projection optical system but also the optical members and the like in the illumination optical system vary in transmittance.

The phenomenon in which the transmittance fluctuates is a phenomenon in which organic substances and the like in the atmosphere undergo a chemical reaction by ultraviolet light and are converted into a cloudy substance, and this cloudy substance adheres to the surface of an optical member. Phenomena in which the transmittance of the optical member itself fluctuates due to the thermal energy saturation effect (compaction), the phenomenon in which the transmittance is recovered by stopping the irradiation of the ultraviolet pulse light, and dust on the surface of the optical member due to the irradiation of the ultraviolet pulse light. A phenomenon in which the transmittance is improved in a short term due to a cleaning effect (cleaning effect) from which is removed. Actually, it is considered that these plural phenomena contribute in a composite manner.

Since a plurality of phenomena proceed in parallel with their respective time constants as described above, it is difficult to control the exposure amount by accurately predicting the variation in the transmittance. In particular, when ArF excimer laser light is used as the exposure light and quartz glass is used as the optical member, the amount of change in transmittance becomes large, so that the distance from the integrator sensor to the image plane (wafer surface) during the exposure is large. It is desirable to measure the amount of change in the transmittance of the entire optical member. Therefore, in an exposure apparatus using ArF excimer laser light as exposure light,
To measure the illuminance (pulse energy) of the exposure light on the image plane of the projection optical system at a predetermined timing during the exposure, and calculate the illuminance on the image plane from the measurement value of the integrator sensor using this measurement result It is considered that the calibration of the coefficient α is performed.

An example of this calibration sequence is assumed as follows. That is, the initial value αA of the coefficient α is calculated by, for example, simultaneously measuring the exposure light with the detachable illuminometer and the integrator sensor arranged on the image plane of the projection optical system. Then, after the exposure to the plurality of shot areas on the wafer is completed, the illuminometer is arranged again on the image plane, and the exposure light is measured simultaneously by the integrator sensor and the illuminometer.
Since the updated value αB of the coefficient α is calculated, thereafter, the exposure amount control is performed using the updated value αB and the measurement value of the integrator sensor. Then, by performing measurement by the illuminometer and the integrator sensor at any time and updating the coefficient α, even if the transmittance of the optical member fluctuates, the exposure amount can be accurately controlled.
The update of the coefficient α is performed according to the time constant of the change of the transmittance,
For example, it is performed for each wafer, for each of a plurality of wafers, or for each lot. With this calibration method, it is possible to accurately cope with spatially uniform transmittance fluctuations of the optical system.

[0007]

As described above, when the transmittance of the optical member from the integrator sensor to the image plane fluctuates substantially uniformly in space, as described above, for example, at the center on the image plane at predetermined time intervals. By actually measuring the illuminance of the exposure light, it is possible to control the exposure amount with high accuracy based on the measurement value of the integrator sensor.

However, actually, since the pattern abundance in the illumination area of the reticle has a coarse and dense distribution, and the transmittance in the illumination area has a high and low distribution, the optical member constituting the projection optical system is actually used. The amount of the incident exposure light varies depending on the position of. In particular, among optical members in the projection optical system, for an optical member (a lens or the like) existing near the reticle or the wafer, the spatial distribution of the amount of incident light substantially corresponds to the distribution of transmittance in the illumination area of the reticle. Therefore, in those optical members, if the transmittance distribution of the reticle in the illumination area is not uniform, the spatial distribution of the incident light amount is also uneven, and the variation amount of the transmittance is also uneven depending on the position.

Therefore, when the distribution of the pattern existence rate of the reticle is non-uniform, the variation of the transmittance of the projection optical system also becomes non-uniform. Is measured and the coefficient α is calibrated based on the measured value, the error of the exposure amount may exceed the allowable range depending on the position on the wafer.

[0010] In this regard, in the case of a scanning exposure type exposure apparatus, the influence of the distribution of the pattern density in the scanning direction of the reticle is offset by the integration effect at the time of scanning exposure. Therefore, even if the pattern existence ratio of the reticle varies in the scanning direction, this does not cause non-uniformity of the fluctuation of the transmittance of the projection optical system. On the other hand, when there is a density distribution of the pattern existence rate in the non-scanning direction orthogonal to the scanning direction, the density distribution remains even by the scanning exposure operation. It changes depending on the position in the direction. Therefore, even if the illuminance of the exposure light is measured at the center of the image plane and the above-described coefficient α is calibrated, the exposure amount becomes excessive or insufficient depending on the position in each shot area on the wafer. Might be.

In view of the foregoing, the present invention has been made in consideration of the above-mentioned circumstances, and when a mask pattern is transferred onto a substrate by a scanning exposure method, the pattern existence ratio of the mask is not uniform in a direction intersecting the scanning direction of the mask. It is also a first object of the present invention to provide an exposure method capable of reducing an error in the exposure amount for the substrate. Further, the present invention provides an exposure method capable of controlling the exposure amount on a substrate such as a wafer at high speed and with high accuracy when a pattern of a mask such as a reticle is transferred onto a substrate such as a wafer by a scanning exposure method. As a second object.

Further, it is a third object of the present invention to provide a mask and an exposure apparatus which can be used when performing such an exposure method.

[0013]

According to a first exposure method of the present invention, a first object (R) is illuminated with an exposure beam, and a projection optical system (P) is irradiated with an exposure beam passing through the pattern of the first object.
L), the exposure area (21W) on the second object (W) is exposed, and the first object and the second object are synchronously scanned in an exposure method. A first step of measuring the relationship between the intensity of the exposure beam at the reference point (14) on the optical path leading to and the intensity of the exposure beam in the exposure area, and controlling the amount of exposure based on the measurement result. In the exposure area, a plurality of measurement points (P
_1, P _2, a second to measure the intensity of the exposure beam ...)
And a third step of controlling the amount of exposure for the second object based on the measurement result.

According to the present invention, a coefficient (correlation coefficient) for calculating the intensity in the exposure area from the intensity of the exposure beam at the reference point based on the measurement result in the first step. α is calculated, and during the subsequent exposure, the intensity in the exposure area is indirectly calculated based on the measured value of the intensity at the reference point and the coefficient α as an example, and the intensity is set to a predetermined value. Exposure amount control is performed so that in this case,
If, for example, ultraviolet pulse light is used as the exposure beam, and the pattern existence rate of the first object is not uniform in a direction (intersecting direction) intersecting the scanning direction of the first object, the projection optical system of the projection optical system is exposed during the exposure. The transmittance fluctuates non-uniformly in the cross direction, and the transmissivity distribution becomes spatially non-uniform.

Therefore, in the present invention, in the second step, the intensity of the exposure beam is measured at a plurality of measurement points along the intersecting direction in the exposure area. A coefficient α _i (i = 1, 2,...) For calculating the intensity in the exposure area can be obtained from the intensity of the point. The coefficient α _i corresponds to the transmittance of the optical system (including the projection optical system) from the reference point to the image plane at each measurement point. Then, the above-mentioned coefficient alpha for example, the average value of the coefficient alpha _i
Is updated and the exposure amount is controlled, thereby reducing the error of the exposure amount in the cross direction on the second object.
In other words, by allocating the exposure amount control error in the exposure area due to the non-uniformity of the transmittance variation to the target exposure amount, the error can be reduced.

In a second exposure method according to the present invention, the second step of the first exposure method is a step of performing exposure on a predetermined surface while controlling an exposure amount based on a measurement result of the first step. And an object in which the distribution of the pattern abundance in a direction (intersecting direction) intersecting with the scanning direction of the first object (intersecting direction) does not pass through the first object, and in the exposure area, the intersecting direction Measurement points (P
_1, P _2, in which is divided into a step of measuring the intensity of the exposure beam ...). In this case, the predetermined surface may be the second object, or may be a dummy object different from the second object, for example, for test exposure.

According to such an exposure method, the transmittance of the optical system from the reference point to the image plane is measured at the plurality of measurement points independently of the distribution of the pattern existence rate of the first object. it can. Therefore, even if the first object is replaced with another object (second mask) and the exposure is continued, the exposure amount control can be performed with high accuracy. In other words, the transmittance of the optical system can be measured each time the first object is replaced. A sensor for measuring the intensity of the exposure beam at a plurality of measurement points in the exposure area can be a sensor with a pinhole-shaped light receiving section for measuring the uniformity of the intensity in the exposure area, or the exposure area can be collectively measured. Any sensor having a large-diameter light-receiving unit capable of measurement may be used. When a sensor having a large-diameter light receiving unit is used, an average value of non-uniform transmittance substantially in the exposure area can be obtained by one measurement.
When a sensor having a pinhole-shaped light receiving section is used, a portion in the exposure area where particularly high exposure amount control accuracy is desired to be maintained can be arbitrarily selected.

In a third exposure method according to the present invention, the first object (R) is illuminated with an exposure beam, and the second object is irradiated with an exposure beam having passed through the pattern of the first object via a projection optical system (PL). In an exposure method in which the first object and the second object are synchronously scanned in a state where the exposure area (21W) on the object (W) is exposed, the distribution of the pattern existence rate on the first object is determined by the The distribution in the direction (intersecting direction) intersecting the scanning direction with respect to the distribution of one object in the scanning direction is made more uniform.

According to the present invention, the occurrence of non-uniformity in the transmittance distribution of the projection optical system is suppressed. That is, the non-uniformity of the transmittance variation of the projection optical system occurs when the density of the pattern abundance of the first object exists in the intersecting direction. If the arrangement is made such that the densities cancel each other, the integrated value of the amount of light incident on the projection optical system after the scanning exposure becomes spatially substantially uniform. For this reason, the transmittance variation also occurs to the same extent depending on the position of the projection optical system, and there is no problem in measuring the intensity of the exposure beam at any position within the exposure area, and the exposure amount control can be performed at high speed and with high accuracy. It can be carried out.

The mask according to the present invention is a mask for scanning exposure in which a pattern for transfer is formed, and the distribution of the pattern presence ratio is different from the distribution in the scanning direction at the time of exposure. The distribution in the non-scanning direction perpendicular to the direction is made more uniform. By using this mask, the third exposure method of the present invention can be performed. This mask is optimized and designed so that when the mask pattern is integrated in the scanning direction, the pattern abundance (for example, the ratio of the area of the light-shielding portion to the area of the pattern region) is substantially uniform in the non-scanning direction. do it.

Next, the exposure apparatus according to the present invention illuminates the first object (R) with an exposure beam, and transmits the second object (R) via the projection optical system (PL) with the exposure beam passing through the pattern of the first object. In an exposure apparatus that synchronously scans the first object and the second object while exposing the exposure area (21W) on the first object, the distribution of the pattern existence rate on the first object is determined by the first object. And a stage system (22, 23) for determining the scanning direction of the first object so that the distribution in the direction intersecting the scanning direction becomes more uniform with respect to the distribution in the scanning direction. With this exposure apparatus, the third exposure method of the present invention can be performed.

Next, in a fourth exposure method according to the present invention, a first object (R) is illuminated with an exposure beam, and the first object (R) is irradiated with an exposure beam having passed the pattern of the first object via a projection optical system (PL). In an exposure method for synchronously scanning the first object and the second object in a state where the exposure area (21W) on the two objects (W) is exposed, the first object and the second object are exposed after a predetermined exposure time has elapsed. At least a part of the optical member of the projection optical system is relatively rotated.

According to such an exposure method, when the distribution of the pattern existence rate of the first object is not uniform in a direction intersecting the scanning direction (intersecting direction), for example, at the stage where the exposure is performed for a certain time, for example, By rotating the optical member on the first object side or the second object side of the projection optical system by a predetermined angle and then performing exposure again, the light quantity of the exposure beam incident on the projection optical system is spatially uniform. Is done. Therefore, the non-uniformity of the variation of the transmittance in the crossing direction in the exposure area of the projection optical system is eliminated, and the exposure control can be performed at high speed and with high accuracy.

For example, when the pattern on the first object is sequentially transferred to a plurality of shot areas on the second object by the scanning exposure method, the first object is sequentially rotated by 180 ° to perform the scanning exposure. Thereby, the light amount of the exposure beam incident on the projection optical system is spatially uniformed.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a projection exposure apparatus of a step-and-scan method used in this embodiment. In FIG. 1, an exposure composed of a pulsed ultraviolet laser beam having a wavelength of 193 nm emitted from an exposure light source 6 composed of an ArF excimer laser light source. The light IL is reflected by the optical path bending mirror 7, and then enters the fly-eye lens 10 as an optical integrator (homogenizer) via the first lens 8A, the optical path bending mirror 9, and the second lens 8B. I do. The light emission timing, light emission frequency, and pulse energy of the exposure light IL emitted from the exposure light source 6 are controlled by the exposure control system 2, and the operation of the exposure control system 2 is a main control for controlling the operation of the entire apparatus. It is controlled by system 1. The exposure light is KrF excimer laser light (wavelength: 248 nm).
m) and other excimer laser light, F ₂ laser light (wavelength 1
57 nm), a harmonic of a YAG laser, a harmonic of a semiconductor laser, or the like.

An aperture stop plate 11 of an illumination system is rotatably disposed on the exit surface of the fly-eye lens 10. Around the rotation axis of the aperture stop plate 11, a circular aperture stop 13 A for normal illumination is provided. , An aperture stop 13B for deformed illumination composed of an eccentric small aperture, an aperture stop 13C for annular illumination, and a small coherence factor (σ) composed of a small circular aperture.
) Is formed. Then, by rotating the aperture stop plate 11 by the drive motor 12 under the control of the main control system 1, an illumination system aperture stop according to the selected illumination condition can be arranged on the exit surface of the fly-eye lens 10. It is configured as follows.

A part of the exposure light IL that has passed through the aperture stop on the exit surface of the fly-eye lens 10 is
After being reflected by the, it is incident on an integrator sensor 16 composed of a photoelectric detector via a condenser lens 15. The detection signal of the integrator sensor 16 is supplied to the exposure amount control system 2 and is converted into digital data in the exposure amount control system 2 via a peak hold circuit and an analog / digital (A / D) converter. In this example, as will be described later, the digital data [digi
t], a coefficient (correlation coefficient) α [mJ / cm ² ] for calculating a pulse energy [mJ / cm ² ] per unit area of exposure light on a wafer as a substrate to be exposed is obtained. α is stored in the exposure control system 2. Then, at the time of exposure, the pulse energy on the wafer is indirectly monitored by multiplying the detection signal of the integrator sensor 16 by the coefficient α. Therefore, the beam splitter 14 corresponds to the reference point of the present invention.

Exposure light I transmitted through beam splitter 14
L denotes a fixed field stop (reticle blind) 18A and a movable field stop 18 sequentially through a first relay lens 17A.
Pass B. The fixed field stop 18A is a field stop that defines the shape of a rectangular illumination area on the reticle R, and the movable field stop 18B is configured to prevent unnecessary portions from being exposed at the start and end of scanning exposure. Used to close the lighting area. The movable field stop 18B is disposed on a conjugate plane with the pattern surface of the reticle R,
A is arranged at a position defocused by a predetermined distance from the conjugate plane.

Exposure light IL that has passed through movable field stop 18B
Illuminates the elongated rectangular illumination area 21R in the pattern area 42 provided on the pattern surface (lower surface) of the reticle R via the second relay lens 17B, the mirror 19 for bending the optical path, and the condenser lens 20. Under the exposure light IL, the pattern in the illumination area 21R of the reticle R is
A predetermined projection magnification M _RW (in this example, M _RW ) via a telecentric projection optical system PL on both sides (or one side on the wafer side).
Is reduced to 1/4, 1/5, 1/6, etc.) and projected onto a rectangular exposure area 21W on the wafer W coated with a photoresist. The wafer (wafer) W is, for example, a semiconductor (silicon or the like).
Alternatively, it is a disc-shaped substrate such as SOI (silicon on insulator). A reticle R as a mask and a wafer W as a substrate to be exposed correspond to a first object and a second object of the present invention, respectively. Hereinafter, the Z axis is taken parallel to the optical axis AX of the projection optical system PL, the Y axis is taken along the scanning direction SD of the reticle R and the wafer W during scanning exposure in a plane perpendicular to the Z axis, and the scanning direction SD The description will be made by taking the X-axis along the non-scanning direction perpendicular to. In this case, the illumination region 21R and the exposure region 21W are slit-shaped regions that are elongated in the non-scanning direction (X direction).

The reticle R is a reticle stage 22
The reticle stage 22 is mounted on the reticle base 23 so as to be continuously movable in the Y direction by a linear motor. Furthermore, reticle stage 2
2 also incorporates a mechanism for finely moving the reticle R in the X, Y, and rotation directions. The position and rotation angle of the reticle stage 22 are measured by a laser interferometer in the reticle stage drive system 3, and the reticle stage drive system 3 operates the reticle stage 22 based on the measured values and control information from the main control system 1. Control. Although not shown, a reticle R is located near the reticle stage 22.
A reticle loader system that is rotated by 80 ° and placed on the reticle stage 22 again is also provided.

On the other hand, the wafer W is held by suction on a wafer holder 24, and the wafer holder 24 is fixed on a Z tilt stage 25 for controlling the focus position (position in the Z direction) and the tilt angle of the wafer W. XY
The XY stage 26 is fixed on the stage 26, and continuously moves the Z tilt stage 25 (wafer W) on the wafer base 27 in the Y direction and stepwise moves in the X and Y directions by, for example, a linear motor system. Z
A wafer stage 28 is constituted by the tilt stage 25, the XY stage 26, and the wafer base 27. The position and the rotation angle of the Z tilt stage 25 are measured by a laser interferometer in the wafer stage drive system 4, and based on the measured values and the control information from the main control system 1, the wafer stage drive system 4 Control behavior. A wafer loader system (not shown) that can place the wafer W on the wafer holder 24 at a desired rotation angle is also arranged near the wafer stage 28.

Although not shown, alignment sensors for detecting the positions of alignment marks on the reticle R and the wafer W are arranged above the reticle stage 22 and above the wafer stage 28, respectively. Alignment between reticle R and each shot area on wafer W is performed based on the detection result of the alignment sensor.

During scanning exposure, the illumination area 21R is irradiated with exposure light IL, and the reticle R is scanned via the reticle stage 22 with respect to the illumination area 21R in the + Y direction (or -Y direction) at a speed VR. Synchronously, the wafer W is scanned via the XY stage 26 with respect to the exposure area 21W in the −Y direction (or + Y direction) at a speed M _RW · VR (M _RW is a projection magnification from the reticle R to the wafer W). Thereby, the pattern image in the pattern area 42 of the reticle R is sequentially transferred to one shot area SA on the wafer W.
The reason that the scanning directions of the reticle R and the wafer W are opposite is that the projection optical system PL performs reverse projection. When the projection optical system PL projects an erect image, the scanning direction of the reticle R and the wafer W is different. The scanning direction is the same (+ Y direction or -Y direction). Thereafter, the XY stage 26 is stepped to move the next shot area on the wafer W to the scanning start position, and then the operation of performing synchronous scanning is repeated in a step-and-scan manner, and each shot on the wafer W is repeated. Exposure to the area is performed. Thereafter, by developing the photoresist on the wafer W and forming a pattern such as etching or ion implantation, a circuit pattern of the layer is formed.

At the time of such exposure, the wafer W
The appropriate amount of exposure is specified for the photoresist applied on top, and if the error of the integrated exposure amount for the photoresist exceeds a predetermined allowable range, the line width of the circuit pattern formed thereafter exceeds the allowable range. As a result, the yield of the finally manufactured semiconductor device decreases. Therefore, in the projection exposure apparatus of this example, the exposure control is performed so that the error of the integrated exposure falls within the allowable range over the entire surface of each shot area on the wafer W.

Therefore, an irradiation amount monitor 29 comprising a photoelectric detector for measuring the illuminance of the exposure light IL on the Z tilt stage 25 and a photoelectric monitor for measuring the illuminance unevenness of the exposure light IL in the exposure area 21W. An uneven illuminance sensor 30 including a detector is provided, and detection signals from the irradiation amount monitor 29 and the uneven illuminance sensor 30 are supplied to the main control system 1. The light receiving surfaces of the irradiation amount monitor 29 and the uneven illuminance sensor 30 are set at the same height as the surface of the wafer W, and the light receiving portion 29a of the irradiation amount monitor 29 is set wider than the exposure area 21W. Further, the uneven illuminance sensor 30 has first and second photoelectric detectors, the first photoelectric detector has a pinhole-shaped light receiving section 31, and the second photoelectric detector has a position X more than the exposure area 21W. This is a CCD type photoelectric conversion element provided with an elongated light receiving section 32 in which a number of fine photoelectric conversion sections are arranged in an array so as to be longer in a direction (non-scanning direction). In this case, the irradiation amount monitor 29, the illuminance unevenness sensor 3
As for the detection signal of 0, the same illuminance (pulse energy per unit area for pulsed light) is measured with respect to irradiation of exposure light of the same level by using, for example, a portable reference illuminometer (not shown). Calibration is performed as follows. Further, with respect to the photoelectric detector having the light receiving section 32 in the form of an array, the calibration of the sensitivity variation among a large number of photoelectric conversion sections is performed.

Next, an example of the distribution of the optical material of the projection optical system PL and the pattern existence ratio of the reticle R used in this embodiment will be described with reference to FIG. FIG. 2 is a perspective view showing from reticle R to wafer W in FIG.
, The projection optical system PL is configured by arranging lens systems L1, L2,..., L5 in order from the reticle R side.
The wavelength of the exposure light IL of this example is 193 nm (ArF excimer laser light), and an optical material having a relatively high transmittance in this wavelength range is synthetic quartz glass (SiO ₂ ), quartz glass doped with impurities such as fluorine, and the like. Fluorite (CaF ₂ ) and magnesium fluoride (MgF ₂ ). Therefore, the lens system L
As the optical material of each lens in 1 to L5, synthetic quartz glass (SiO ₂ ) and fluorite (CaF ₂ ) are used.
In this case, in particular, in the former quartz glass, since the transmittance gradually changes relatively largely by continuous irradiation of ultraviolet pulse light, it is desirable to actually measure the transmittance at a predetermined time interval during the exposure operation, for example. .

In FIG. 2, the pattern region of the reticle R is actually formed on the lower surface of a glass substrate made of synthetic quartz or fluorite, but for convenience of explanation, the pattern region appears on the upper surface of the glass substrate. The pattern area of the reticle R is surrounded by a rectangular frame-shaped light-shielding band 41, and the pattern existence rate kP (0 ≦ kP ≦
1) That is, the ratio of the area of the light-shielding portion to the area of the pattern region is not uniform in the non-scanning direction (X direction) of the reticle R. That is, the pattern area of the reticle R is divided into five areas 42A to 42 of different widths in the non-scanning direction.
Divided into E (it is also possible to subdivide it)
The pattern existence rates of the areas 42A and 42C are kP1, the area 4 is
Assuming that the pattern existence rates of 2B and 42D are kP2 and the pattern existence rate of the area 42E is kP3, the pattern existence rate kP2 is highest and the pattern existence rate kP1 is lowest as follows.

KP1 <kP3 <kP2 (1) Further, the transmittance of the region having the pattern abundance kP is substantially (1-
kP). Therefore, if the transmittance for exposure light IL of the glass substrate itself of the reticle R and T _GP, the average value of the transmittance of the portion of the pattern presence rate kP is substantially T _GP (1-kP)
It is represented by Therefore, the transmittance distribution of the reticle R is highest in the areas 42A and 42C in the non-scanning direction,
B and 42D are the lowest. However, actually, as for the reticle R, as an example, the transmittance TR of the entire pattern area with respect to the wavelength of the exposure light IL, that is, the areas 42A to 42A
The average transmittance of 2E is obtained in advance by calculation or actual measurement, the transmittance TR is stored as exposure data in the main control system 1 in FIG. 1, and the data of the transmittance distribution itself is not necessarily obtained. Absent.

When the exposure area IL on the reticle R is irradiated with the exposure light IL, the lens system L1 closest to the reticle and the lens system L5 closest to the wafer in the projection optical system PL.
The illumination regions 43 and 47 mainly by the zero-order light are slit-like regions elongated in the non-scanning direction, which are substantially similar to the illumination region 21R, and the illumination regions 44 and 46 of the inner lens systems L2 and L4 are in the non-scanning direction. The illumination area 45 of the lens system L3 near the optical Fourier transform plane (pupil plane) with respect to the pattern surface of the reticle R becomes a substantially circular area. Assuming that the regions corresponding to the regions 42A to 42E in the irradiation regions 43 and 47 are the regions 43A to 43E and the regions 47A to 47E, respectively, the amount of light passing through the regions 43A to 43E and the regions 47A to 47E is the region within the illumination region 21R. It is almost proportional to the transmittance of 42A to 42E.

Hereinafter, an example of the exposure amount control operation of this embodiment will be described. [First Step] First, in FIG.
After removing reticle R from above, wafer stage 2
8, the light receiving surface 29a of the irradiation amount monitor 29 is moved so as to completely cover the exposure area 21W of the projection optical system PL. Then, the main control system 1 causes the exposure light source 6 to perform pulse emission through the exposure amount control system 2, and performs a detection signal S 1 [digit] of the integrator sensor 16 and a detection signal S 2 of the irradiation amount monitor 29 for each pulse emission. And the detection signal S2 is converted into the pulse energy S3 [m
J / cm ² ], and the value β (= S3 / S1) of the ratio of the pulse energy S3 to the detection signal S1 is calculated.
Then, the main control system 1 causes the exposure light source 6 to emit a plurality of pulses, for example, and obtains an average value β0 of the values β obtained for each pulse emission. Next, the main control system 1 multiplies the value β0 by the known overall transmittance TR of the reticle R, and calculates the pulse energy (exposure amount) per unit area in the exposure area 21W from the detection signal S1 of the integrator sensor 16. The coefficient α for the calculation is calculated as follows.

Α = β0 · TR (2) When obtaining the above value β, the pinhole-shaped light receiving section 31 of the illuminance unevenness sensor 30 is moved to, for example, the center of the exposure area 21W, and The exposure amount in the exposure area 21W may be actually measured from the detection signal. Thereafter, the detection signal S of the integrator sensor 16 is calculated by the following equation.
From 1, the pulse energy S3 per unit area in the exposure region 21W can be calculated.

S3 = α · S1 (3) [Second Step] Next, the reticle R is placed on the reticle stage 22, and the reticle R and the wafer W are scanned synchronously as shown in FIG. Do. At this time, the emission frequency of the exposure light IL is f, the scanning speed of the wafer W in the scanning direction SD (Y direction) is VW, the width of the exposure region 21W in the scanning direction SD is D, and the pulse width of the exposure light IL is Assuming that the minimum number of exposure pulses determined by the variation is N _min , the wafer W
The emission frequency f and the scanning speed VW are determined so that the number N of exposure pulses to each point above is an integer satisfying the following condition. The main control system 1 and the exposure control system 2 perform scanning exposure so that the following conditions are satisfied.

[0043] N = f · D / VW ≧ N min (4) In addition, the proper amount of exposure for the photoresist on the wafer W (energy per unit area) P [mJ / c
m ² ], assuming that the exposure amount for each pulse emission of the exposure light IL is S3, the appropriate exposure amount is obtained for each point on the wafer W when the following expression is satisfied for each pulse emission using Expression (3). can get.

P = N · S3 = N · α · S1 (5) Therefore, the exposure control system 2 sets the detection signal S1 of the integrator sensor 16 so as to satisfy the condition of the expression (5) within a predetermined allowable range. The output of the exposure light source 6 is controlled. When actually setting the accurate level of the detection signal S1 of the integrator sensor 16 with respect to the appropriate exposure amount P, test printing is performed while changing the detection signal S1 by a predetermined level, and the best pattern is formed after development. The value of the detection signal S1 at the time of the execution may be obtained.

When the above scanning exposure is continuously performed, (5)
The coefficient α in the equation changes gradually. That is, in FIG. 2, the wafer W moves in the scanning direction SD with respect to the exposure region 21W in synchronization with the movement of the pattern region of the reticle R in the scanning direction SD (Y direction) with respect to the illumination region 21R of the exposure light IL. When moved, the areas 43A to 43 of the irradiation areas 43 and 47 are moved.
The irradiation energy for E and the regions 47A to 47E is
Each of them is approximately proportional to the transmittance of the regions 42A to 42E.
Therefore, the distribution of the irradiation energy of the exposure light IL to the lenses L1 and L5 in the non-scanning direction (X direction) becomes non-uniform without being averaged even by the scanning exposure, and the transmittance of the lens systems L1 and L5 varies. Becomes non-uniform in the non-scanning direction. Similarly, the amount of change in the transmittance of the inner lens systems L2 and L4 is also substantially non-uniform in the non-scanning direction.
Therefore, the fluctuation amount of the transmittance of the projection optical system PL as a whole also becomes non-uniform in the non-scanning direction.
It is difficult to accurately determine the state of the amount of fluctuation by measurement at one of the points. Therefore, in this example, each time a predetermined number of wafers or a predetermined lot (for example, one lot) of wafers are subjected to scanning exposure, the beam splitter 14 (reference point) of FIG.
Of the transmittance distribution of the optical system from the wafer W to the wafer W is measured.

[Third Step] In this step, in order to measure the transmittance distribution of the optical system from the beam splitter 14 to the wafer W, the reticle R is removed from the reticle stage 22 in the state of FIG. The pinhole-shaped light receiving section 31 of the uneven illuminance sensor 30 is moved outward in the non-scanning direction (X direction).

FIG. 3 shows a state in which the reticle R has been removed and the pinhole-shaped light receiving section 31 has been moved outside the exposure area 21W in FIG. 1. In FIG. 3, the illumination for measuring the transmittance distribution is shown. The region 21R is irradiated with the exposure light IL for a predetermined number of pulses. At this time, the lens systems L1 and L1
In the irradiation regions 43 and 47 of FIG.
3C and 47A, 47C have the lowest transmittance, and the area 43
Since the transmittances of B, 43C and 47B, 47C are the highest, the light quantity of the areas 48A, 48C is the smallest in the exposure area 21W, and the light quantity of the areas 48B, 48D is the highest. From the state of FIG. 3, the main control system 1 moves the uneven illuminance sensor 30 in the −X direction indicated by the arrow 49, scans the exposure area 21 </ b> W in the non-scanning direction with the pinhole-shaped light receiving unit 31, and emits pulsed light. Each time the integrator sensor 16 of FIG.
Detection signal S1 [digit] and pinhole-shaped light receiving section 3
The detection signal S4 at 1 is taken in. Further, the main control system 1 converts the detection signal S4 into a pulse energy S5 per unit area.
The value β (= S5 / S1) of the ratio of the pulse energy S5 to the detection signal S1 is calculated in terms of [mJ / cm ² ]. The value β of this ratio is also a value corresponding to the transmittance of the optical system (excluding the reticle R) including the projection optical system PL from the beam splitter 14 to the wafer W.

Also, as shown in FIG.
21W in the non-scanning direction of the pinhole-shaped light receiving portion 31
The position is a measurement point separated by a predetermined interval for each pulse emission
P₁, P _Two, ... P_n(N is an integer of 2 or more).
The center of the exposure area 21W in the non-scanning direction is
The closest measurement point is P_aAnd Example of the number of measurement points (n)
For example, it is about 10 to 50, and in the example of FIG.
3. Therefore, the measurement point is the non-scanning method of the exposure area 21W.
Are distributed evenly over the entire surface, and each measurement point P_k(k = 1 ~
n), the ratio value β (hereinafter “β_k")
(= S5 / S1) is calculated. This is the projection optical system P
The distribution of the transmittance of the optical system including L in the non-scanning direction is measured.
Is equivalent to

FIG. 4B shows the ratio value thus calculated.
An example of β is shown, and in FIG.
Each measurement point P in the inspection direction (X direction)_kPosition, vertical axis is each measurement
Point P _kThe value of the ratio β_kIs shown. FIG. 4 (A) and
(B), in the regions 48A and 48C where the amount of light is small, the ratio
The value β is also small, and in the areas 48B and 48D where the amount of light is large,
It can be seen that the ratio value β also increases. Next, the main control system
1 is the n ratio values β_kThe average value β1 is obtained, and this value β
1 multiplied by the known total transmittance TR of the reticle R
From the detection signal S1 of the integrator sensor 16 to the exposure area 2
Pulse energy per unit area at 1 W (exposure amount)
Is calculated as follows.

Β1 = (β ₁ + β ₂ +... + Β _n ) / n (6) α = β 1 · TR (7) [Fourth Step] In this step, the reticle stage 2 shown in FIG.
The reticle R is placed on the wafer 2 again, and scanning exposure is performed on the next wafer to be exposed. Also in this case, the exposure amount control is performed based on the expressions (4) and (5), but the coefficient α in the expression (7) is used as the coefficient α in the expression (5). When exposing by exchanging the reticle R with another reticle,
The transmittance TR of the reticle in the equation (7) may be replaced with the overall transmittance TR1 of the reticle after replacement.

As described above, in this embodiment, even when the transmittance of the projection optical system PL varies non-uniformly in the non-scanning direction, the entire transmission of the optical system from the beam splitter 14 including the projection optical system PL to the wafer W is performed. Since the distribution of the ratio value β corresponding to the ratio in the non-scanning direction is measured, and the coefficient α is updated using the average value β1, the error of the integrated exposure amount for each point on the wafer W is set to the target value. Can be sorted by ±. Therefore, the error can be minimized on average, and the control accuracy of the exposure amount is improved.

This will be further described. For example, FIG.
In (A), a measurement point P _a substantially at the center of the exposure area 21W.
Assuming that the ratio value β is determined using only the measured value of the ratio, the ratio value β becomes the smallest value β2 as shown in FIG. The maximum error Δβ2 of the value β is about twice the maximum error Δβ1 in the case of FIG. 4B in the above embodiment. Therefore, the coefficient α is updated using the average value of the transmittance distribution over the entire exposure area 21W, as compared with the case where the transmittance is measured only at one point in the exposure area 21W and the coefficient α is updated. Thereby, the control accuracy of the exposure amount is improved.

In addition to the case where the distribution of the pattern existence rate of the reticle R is not uniform in the non-scanning direction as described above, for example, in FIG. When switching to the aperture stop 13A and suddenly changing the illumination condition from illumination with a small σ value to illumination with a large σ value, nonuniformity of transmittance may appear irrespective of the reticle pattern. Moreover, this non-uniformity is caused not only by the projection optical system PL but also by the relay lens system 17.
A and 17B also cannot be dealt with by changing the reticle pattern as described below.

In such a case as well, the calibration of the coefficient α by the method of the above embodiment can maintain a high exposure amount control accuracy. Incidentally, in the above embodiment, (6) is used the simple average β1 value beta _k of the ratio as shown in equation sets weights WG _k for each measuring point P _k, high exposure amount control accuracy Is necessary, for example, a portion including a pattern with a small line width has a weight W
The coefficient α may be updated by increasing G _k to obtain a weighted average β4 of the ratio value β _k , and substituting the weighted average β4 for β1 in the equation (7). As a result, it is possible to reduce the error in the amount of exposure in a region having a smaller line width, and to reduce the error in the line width of the finally formed circuit pattern as a whole, thereby improving the device yield.

In the case where simple averaging is performed, the number of measurement points in a portion requiring high exposure amount control accuracy may be increased. Thereby, the same effect as that of the weighted average can be obtained.
In addition, instead of scanning the exposure area 21W with the pinhole-shaped light-receiving section 31, as shown in FIG. 5, the array-shaped elongated light-receiving section 32 of the illuminance unevenness sensor 30 is covered so as to cover the exposure area 21W in the non-scanning direction. You may move. In this case, FIG.
By converting the detection signal at each photoelectric conversion unit of the light receiving unit 32 into pulse energy per unit area, a series of ratio values β in FIG. 4B can be obtained at a time, and the measurement time can be reduced. Can be shortened.

Further, instead of using the uneven illuminance sensor 30, as shown in FIG.
Alternatively, the total energy of the exposure light IL incident on the exposure area 21W may be measured by moving the large-diameter light receiving section 29a to a position covering the exposure area 21W. Also in this case, the detection signal S1 of the integrator sensor 16 and the detection signal S2 of the irradiation amount monitor 29 are simultaneously taken in, the detection signal S2 of the irradiation amount monitor 29 is converted into pulse energy S3 per unit area, and the pulse for the detection signal S1 is converted. The value β3 (= S3 / S1) of the ratio of the energy S3 is calculated. The value β of this ratio
3 can be regarded as the average value of the ratio value (= S3 / S1) over the entire non-scanning direction of the exposure region 21W indicated by the curve 49 in FIG. 6B. Therefore, the value β3 corresponding to the average value of the variation of the transmittance distribution is substituted for β1 in the equation (7) to calculate the coefficient α, and the exposure amount is controlled by using the coefficient α to thereby control the exposure. The amount error can be distributed above and below the target exposure amount to reduce it.

In the measurement using the irradiation amount monitor 29, the dispersion of the transmittance distribution in the exposure area 21W can be substantially averaged by one measurement, and the calibration of the coefficient α can be performed at high speed. This is effective when frequently changing the process or the exposure condition in which the transmittance needs to be frequently measured. In the above embodiment, the first
In the step and the third step, the reticle R is detached from the reticle stage 22 to measure the transmittance. For example, a transparent glass substrate is provided at a position on the reticle stage 22 away from the reticle R in the scanning direction. A reference plate (corresponding to an object having a known transmittance distribution) may be arranged, and the reference plate may be moved to the illumination area 21R to measure the transmittance. Thereby, measurement efficiency can be increased.

Further, in the first step and the third step, the transmittance may be measured through the reticle R. In this case, the entire area of the pattern area of the reticle R is scanned with respect to the illumination area 21R during measurement, and the obtained transmittance distribution (distribution of the ratio value β) may be averaged in the scanning direction. Next, a second embodiment of the present invention will be described with reference to FIG.
A description will be given with reference to FIGS. Also in this example, exposure is performed using the projection exposure apparatus shown in FIG. 1, except that a reticle in which the pattern presence ratio is made as uniform as possible in the non-scanning direction is used instead of the reticle R.

FIG. 7A shows a reticle R used in this embodiment.
FIG. 7A shows a state where A is mounted on the reticle stage 22 of FIG. 1. In FIG.
In the pattern area 1, a pattern 5 having a high average transmittance is provided.
0A and the scanning direction SD (Y
(Patterns) 50B and 50C having high average transmittances, respectively, are formed so as to be separated from each other in the direction (direction). Therefore, the distribution in the non-scanning direction (X direction) of the integral value of the pattern existence ratio of the reticle RA in the scanning direction SD in the non-scanning direction (X direction), that is, the distribution in the non-scanning direction of the transmittance of the reticle RA as a whole excluding both ends. It is almost uniform. In this case, the reticle RA is moved in the scanning direction SD with respect to the illumination area 21R of the exposure light.
The distribution of the average transmittance ΔT in the non-scanning direction when scanning in the non-scanning direction is almost proportional to the integral value of the pattern abundance in the scanning direction, and the transmittance ΔT is represented by the curve in FIG. As shown by 52, the light is substantially uniform in the non-scanning direction (X direction).

In this case, the allowable value of the uniformity of the distribution of the transmittance ΔT in the non-scanning direction is, for example, about 1/5 of the standard value of the illuminance unevenness on the image plane of the exposure apparatus except for both ends. is there. Assuming that the standard value is, for example, 0.5 to 1%, the allowable value of the uniformity of the transmittance ΔT is about 0.1 to 0.2%. As a result, when scanning exposure is performed using the reticle RA, each lens system in the projection optical system PL is irradiated with exposure light with a substantially uniform intensity distribution in the non-scanning direction.
The transmittance changes almost uniformly in the non-scanning direction. Therefore, since the amount of change in the transmittance of the projection optical system PL is substantially uniform in the non-scanning direction, the pinhole-shaped light receiving unit 31 is moved to only the measurement point at the center of the exposure area 21W, for example. 16 and the uneven illuminance sensor 30, the transmittance is measured and the coefficient α is updated, so that the calibration time of the coefficient α can be shortened and high exposure amount control accuracy can be obtained. In this case, the throughput of the exposure step is also improved.

Further, the irradiation amount monitor 29 may be used instead of the uneven illuminance sensor 30. Further, since the variation of the transmittance of the projection optical system PL is substantially uniform in the non-scanning direction, for example, when a predetermined regularity is observed in the variation of the transmittance, the exposure area 21W In the period before the exposure amount is actually measured and the coefficient α is calibrated, the fluctuation amount of the coefficient α may be predicted by predictive control, and the exposure amount control may be performed based on the predicted value. Thereby, the control accuracy of the exposure amount is improved.

On the other hand, FIG. 7C shows a reticle RB in which the distribution of the pattern presence ratio in the non-scanning direction is non-uniform. In FIG. 7C, the reticle RB is surrounded by a light-shielding band 41. The patterns 51A and 51C having a high average transmittance and the patterns 51A and 51C
, Patterns 51B, 51D, and 51B, each having a high average transmissivity, are arranged so as to be separated from each other in the non-scanning direction (X direction).
51E are formed. Accordingly, the distribution of the integral value of the pattern presence ratio of the reticle RB in the scanning direction SD in the non-scanning direction, that is, the average transmittance ΔT in the non-scanning direction when the reticle RB scans the illumination region 21R. The distribution becomes non-uniform as shown by the curve 53 in FIG.

As a result, when scanning exposure is performed using the reticle RB, each lens system in the projection optical system PL is irradiated with exposure light having an uneven intensity distribution in the non-scanning direction. The rate varies non-uniformly in the non-scanning direction. Therefore, when reticle RB is used, the first
It is desirable to control the exposure amount by the method of the embodiment.

Similarly, when scanning exposure is performed using a reticle RC having patterns 54A and 54B separated by a light shielding portion 55 in the non-scanning direction as shown in FIG. Since the transmittance variation becomes non-uniform in the non-scanning direction, it is desirable to control the exposure amount by the method of the first embodiment. On the other hand, when the scanning exposure is performed using the reticle RD having the patterns 56A and 56B separated in the scanning direction by the light shielding portion 57 as shown in FIG. Because it is almost uniform in the scanning direction,
Exposure amount control can be performed at high speed and with high accuracy by a method of measuring the transmittance at a small number of measurement points.

Next, a third embodiment of the present invention will be described with reference to FIGS. 1, 2 and 9. In this example, the projection exposure apparatus shown in FIG. 1 is used. In this example, the relative position between the projection optical system PL itself having a non-uniform transmittance distribution and the reticle causing the non-uniform transmittance distribution is changed as needed. The point of change is different. FIG. 2 shows a state in which exposure is performed in the present example. As shown in FIG. 2, exposure is performed by first synchronously scanning the reticle R and the wafer W in the scanning direction SD. Since the transmittance distribution of the reticle R is non-uniform in the non-scanning direction (X direction), if such exposure is continued, the transmittance distribution of each of the lens systems L1 to L5 of the projection optical system PL, in particular, the reticle R and the wafer Lens system L1 close to W
The transmittance distribution of L5 becomes non-uniform in the non-scanning direction. Therefore, in this example, in order to prevent a part of the lens systems L1 to L5 from being excessively irradiated, for example, after exposing a plurality of wafers, a predetermined number of lenses in the projection optical system PL are set to two points. As indicated by the dashed lines 43R to 47R, the optical axis A
It is rotated by a predetermined angle (for example, about 10 °) in the Θ direction around X. The lens to be rotated in this way may be a lens in which the distribution of the irradiation energy in the projection optical system PL is substantially similar to the transmittance distribution of the reticle R, that is, only the lens system L1 near the reticle and the lens system L5 near the wafer. .

By gradually rotating the predetermined lens in the projection optical system PL as described above, the exposure light IL is irradiated to the lens systems L1 to L5 in the projection optical system PL with a substantially uniform energy distribution. The transmittance of the projection optical system PL changes almost uniformly in the non-scanning direction. Therefore, by performing the exposure control based on the transmittance measurement at a small number of measurement points as in the second embodiment, the error in the exposure can be reduced.

As described above, the method of rotating the lens in the projection optical system PL is such that the transmittance of the reticle R is high particularly in the outer peripheral portion of the illumination area 21R, and the lens systems L1 to L1 in the projection optical system PL are high.
This is effective when the intensity distribution of the exposure light is high at the outer periphery of L5. As another method of changing the relative position between the projection optical system PL and the pattern of the reticle R, a method of rotating the reticle by 180 ° during exposure can be considered.

FIG. 9 is an explanatory view in the case of rotating the reticle by 180 °. First, as shown in FIG. 9A, the reticle RE and the wafer W are synchronized with the projection optical system PL in the Y direction. By scanning, a reduced image of the pattern of the reticle RE is transferred to the shot area SA1 on the wafer W. In this case, the pattern region of the reticle RE has a width substantially equal to the non-scanning direction (X direction) and a plurality of regions 58A to 58A-5.
8D, and the value obtained by integrating the pattern existence ratio (the ratio of the light-shielding portion) of these regions 58A to 58D in the scanning direction (Y direction) gradually decreases from the region 58A to the region 58D. Therefore, the reticle R shown in FIG.
The average transmittance of E gradually increases from the region 58A to the region 58D, and the transmittance distribution of the projection optical system PL
Are substantially antisymmetric with respect to the non-scanning direction about the optical axis. Therefore, in the irradiation regions 43 and 47 of the projection optical system PL, particularly, in the irradiation regions 43 and 47 of the lens systems L1 and L5, the transmittance gradually largely changes from the region 58A to the portion corresponding to the region 58D.

Therefore, in this example, after exposing a plurality of wafers, for example, the reticle RE is exposed as shown in FIG.
Is rotated by 180 °, and the wafer W ′ to be exposed is also rotated by 180 ° with respect to the case of FIG. The wafer W ′ to be exposed is rotated by 180 °
This is to ensure that the circuit pattern transferred to each upper shot area is the same as the circuit pattern transferred to each shot area on the wafer W. And reticle RE
And the wafer W ′ is synchronously scanned with respect to the projection optical system PL in the Y direction, so that the shot area S on the wafer W ′ is
A pattern image of the reticle RE is transferred to A2. At this time, the average transmittance distribution of the reticle RE in the non-scanning direction is a distribution obtained by inverting the transmittance distribution of the reticle RE in FIG. 9A about the optical axis. (B)
The irradiation areas 43 and 47 on the lens systems L1 and L5 in the projection optical system PL are irradiated with the exposure light IL with an intensity distribution that is antisymmetric in the non-scanning direction with respect to the case of FIG.

Thereafter, each time substantially the same number of wafers are exposed, the reticle RE and the wafer are rotated by 180 ° to perform exposure. As a result, the energy of the exposure light IL applied to the lens systems L1 and L5 in the projection optical system PL becomes uniform in the non-scanning direction, and the variation in the transmittance of the projection optical system PL is also made uniform in the non-scanning direction. . Therefore, by performing transmittance measurement at a small number of measurement points as in the second embodiment, it is possible to perform exposure amount control with high accuracy. This method is particularly effective when the distribution of the integration value of the pattern abundance in the scanning direction in the non-scanning direction, and hence the distribution of the average transmittance in the non-scanning direction, are almost antisymmetric about the optical axis. It is valid.

It should be noted that the exposure light IL of the above embodiment is replaced with a DF instead of an excimer laser or an F ₂ laser.
B (Distributed feedback) A single wavelength laser in the infrared or visible region oscillated from a semiconductor laser or a fiber laser, for example, doped with erbium (Er) (or both erbium and ytterbium (Yb)). It is also possible to use harmonics that have been amplified by a fiber amplifier and wavelength-converted to ultraviolet light using a nonlinear optical crystal.

For example, the oscillation wavelength of a single-wavelength laser is set to 1.
If it is in the range of 544 to 1.553 μm, 193-1
An 8th harmonic within the range of 94 nm, that is, ultraviolet light having substantially the same wavelength as the ArF excimer laser is obtained, and when the oscillation wavelength is within the range of 1.57 to 1.58 μm, 157 to 1
The 10th harmonic within the range of 58 nm, that is, ultraviolet light having substantially the same wavelength as that of the F ₂ laser is obtained. Further, when the oscillation wavelength is in the range of 1.03 to 1.12 μm, a seventh harmonic having a generation wavelength in the range of 147 to 160 nm is output, and particularly, the oscillation wavelength is in the range of 1.09 to 1.106 μm. When the inner, generation wavelength 7 harmonic in the range of 157～158Nm, i.e. F ₂ laser and ultraviolet light having almost the same wavelength can be obtained. As the single-wavelength oscillation laser in this case, for example, an ytterbium-doped fiber laser can be used.

Further, the projection exposure apparatus of the above embodiment adjusts the illumination optical system and the projection optical system and assembles each component electrically, mechanically or optically. At this time, in FIG. 1, the integrator sensor 16, the irradiation amount monitor 29, the illuminance unevenness sensor 30
Are also attached to the beam splitter 14 and the Z leveling stage 25 in a predetermined positional relationship. It is desirable that the work in these cases be performed in a clean room where the temperature is controlled.

Then, a device such as a semiconductor element is manufactured by subjecting the wafer exposed as described above to a developing step, a pattern forming step, a bonding step, packaging, and the like. Further, the present invention can be applied to the production of a display device such as a liquid crystal display device or a plasma display device, or a device such as a thin film magnetic disk. In addition, the present invention can be applied to manufacturing a photomask for a projection exposure apparatus.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted without departing from the gist of the present invention.

[0076]

According to the first and second exposure methods of the present invention, when a pattern of a first object (mask) is transferred onto a second object (substrate) by a scanning exposure method, an optical beam is used as an exposure beam. Even if an ultraviolet pulse light having a large fluctuation amount of the transmittance of the system is used, the transmittance state after the fluctuation can be substantially measured, so that the error of the exposure amount for the second object can be reduced.

According to the third exposure method of the present invention,
Since the distribution of the integrated value of the transmittance after the scanning exposure can be made substantially uniform in the direction intersecting the scanning direction of the first object, the variation of the transmittance of the optical member of the projection optical system also becomes substantially uniform. Therefore, the exposure amount control for the second object can be performed at high speed and with high accuracy. And according to the mask of the present invention,
The third exposure method of the present invention can be used.

According to the fourth exposure method of the present invention,
Even if the pattern existence rate of the first object is non-uniform in the direction intersecting with the scanning direction of the first object, the non-uniformity of the transmittance fluctuation of the optical system itself can be largely suppressed. Exposure amount control can be performed at high speed and with high accuracy.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a projection exposure apparatus used in an embodiment of the present invention.

FIG. 2 is an enlarged perspective view showing a reticle R, a projection optical system PL, and a wafer W in FIG.

FIG. 3 is a perspective view showing a state in which a pinhole-shaped light receiving section 31 of the uneven illuminance sensor 30 is moved outside an exposure area 21W of FIG.

4A is an enlarged plan view showing a state in which a pinhole-shaped light receiving section 31 scans an exposure area 21W, and FIG. 4B is an example of a ratio value β measured at each point of the exposure area 21W. FIG. 3C is a diagram illustrating an example of a ratio value β measured at the center of the exposure area 21W.

FIG. 5 is an enlarged plan view showing a state in which an elongated light receiving section 32 in an array is moved so as to cover an exposure area 21W.

FIG. 6A shows an exposure area 21W on an irradiation amount monitor 29;
Enlarged plan view showing a state in which the light quantity of
(B) is a ratio value β measured by the irradiation amount monitor 29.
It is a figure showing an example of.

FIG. 7 is a diagram showing a reticle used in a second embodiment of the present invention, in which the pattern presence ratio is made uniform in the non-scanning direction, and a reticle for comparison.

FIG. 8A is a diagram showing a reticle having a pattern existence ratio non-uniform in the non-scanning direction, and FIG. 8B is a diagram showing a reticle having a pattern existence ratio uniform in the non-scanning direction.

FIG. 9 is an explanatory diagram in the case where exposure is performed by rotating the reticle RE by 180 ° in the third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main control system, 2 ... Exposure amount control system, 6 ... Exposure light source, 11
... Aperture stop plate, 18A ... Fixed field stop, R, RA, R
D, RE: reticle, PL: projection optical system, L1 to L5 ...
Lens system, W: wafer, 14: beam splitter, 16
... Integrator sensor, 21R ... Illumination area, 21W ...
Exposure area, 22: reticle stage, 28: wafer stage, 29: irradiation amount monitor, 30: uneven illuminance sensor, 3
1. Pinhole-shaped light-receiving part, 32 ... Array-shaped elongated light-receiving part

Claims (9)

[Claims] Illuminating a first object with an exposure beam;
In an exposure method for synchronously scanning the first object and the second object while exposing an exposure area on a second object via a projection optical system with an exposure beam having passed through the pattern of the object, A first step of measuring the relationship between the intensity of the exposure beam at a reference point on the optical path to the first object and the intensity of the exposure beam in the exposure area; and controlling the amount of exposure based on the measurement result. Performing a second step of measuring the intensity of the exposure beam at a plurality of measurement points along a direction intersecting the scanning direction of the second object in the exposure area while performing the second step, based on the measurement result, A third step of controlling the amount of exposure of the object. Illuminating a first object with an exposure beam;
In an exposure method for synchronously scanning the first object and the second object while exposing an exposure area on a second object via a projection optical system with an exposure beam having passed through the pattern of the object, A first step of measuring the relationship between the intensity of the exposure beam at a reference point on the optical path to the first object and the intensity of the exposure beam in the exposure area; and controlling the amount of exposure based on the measurement result. A second step of performing exposure on a predetermined surface while performing, without passing through the first object, or through an object whose distribution of pattern abundance in a direction intersecting the scanning direction of the first object is known, A third step of measuring the intensity of the exposure beam at a plurality of measurement points along a direction intersecting the scanning direction of the second object in the exposure area; and an exposure amount for the second object based on the measurement result. 4th process to control An exposure method, comprising: 3. The exposure method according to claim 1, wherein when measuring the intensity of the exposure beam at the plurality of measurement points, the intensity of the exposure beam is measured over the entire surface of the exposure area. . Illuminating a first object with an exposure beam;
An exposure method for synchronously scanning the first object and the second object while exposing an exposure area on a second object via a projection optical system with an exposure beam having passed through the pattern of the object, comprising: An exposure method, wherein the distribution of the pattern abundance ratio is made more uniform in a direction intersecting the scanning direction with respect to the distribution of the first object in the scanning direction. 5. A scanning exposure mask on which a transfer pattern is formed, wherein the distribution of the pattern abundance is in a non-scanning direction perpendicular to the scanning direction distribution at the time of exposure. Characterized in that the distribution of the colors is made more uniform. 6. illuminating a first object with an exposure beam;
An exposure apparatus that synchronously scans the first object and the second object while exposing an exposure area on a second object via a projection optical system with an exposure beam having passed through the pattern of the object; Has a stage system that determines the scanning direction of the first object such that the distribution of the pattern existence ratio becomes uniform in the direction intersecting the scanning direction with respect to the distribution of the first object in the scanning direction. An exposure apparatus comprising: 7. illuminating a first object with an exposure beam;
In an exposure method of synchronously scanning the first object and the second object while exposing an exposure area on a second object via a projection optical system with an exposure beam having passed through a pattern of the object, An exposure method, wherein after the lapse of time, the first object and at least a part of the optical members of the projection optical system are relatively rotated. 8. The exposure method according to claim 7, wherein at least a part of the optical member of the projection optical system is rotated. 9. The exposure method according to claim 7, wherein the first object is rotated by 180 °.