JP2000232049A - Aligner and device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce change in the optical performance of a projection optical system which is generated during scanning exposure. SOLUTION: In this aligner for a scanning system and a device manufacturing method, scanning exposure of a pattern for an original sheet is performed on a substrate via a projection optical system, while the original sheet 50 and the substrate 61 are scanning-moved to a slit-shaped illumination light and the projection optical system 60. In order to reduce changes in the optical performance of the projection optical system which is generated during scanning exposure, shape and illuminance distribution of the slit-shaped illumination light are set by a variable slit 43 and an optical means 36. This setting is so performed that light energy density of a part of a slit-shaped illumination light which passes the vicinity of the center of the optical axis of the projection optical system when scanning exposure is performed is made smaller than that of both side parts of the slit-shaped illumination light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning type exposure apparatus and a device manufacturing method using the same, and more particularly, to a method for reducing a change in optical performance such as astigmatism occurring during exposure. About things.

[0002]

2. Description of the Related Art Conventionally, a scan type semiconductor exposure apparatus for exposing and transferring a pattern on a reticle onto a wafer by a scanning operation has been known. FIG. 13 is a schematic view of a main part of a general scan type semiconductor exposure apparatus. The exposure apparatus illuminates a part of the pattern 200 on the reticle 50 with a slit-like illumination light beam 201 by an illumination system using a continuous light source or a pulsed light source, as shown in FIG. Projection system 60
To reduce and project on the wafer 61. And at this time,
While scanning the reticle 50 and the wafer 61 with respect to the projection system 60 and the slit-shaped illumination light beam 201 at the same speed ratio as the reduction ratio of the projection system 60, as shown by arrows 202 and 203, the reticle 50 and the wafer 61 are scanned. Is transferred to one or more chip areas on the wafer 61.

[0003]

As described above, in the conventional scanning type semiconductor exposure apparatus, the slit-shaped illumination is performed, so that the projection direction of the reticle and the lens close to the wafer cannot be changed in the scanning direction during the exposure. The method of changing the temperature rise differs between the slit direction and the slit direction. This phenomenon becomes a problem particularly when i-line is used as exposure light.

That is, quartz is often used as a lens glass material, and the transmittance of quartz is about 95% (t = 10 m
m), but the heat transfer coefficient of quartz is 1.4 [W / m · K].
(0 ° C.) and other glass materials such as fluorite 10.3
Smaller than [W / m · K] (0 ° C.), it is difficult to release heat. Even more problematic is the large change in refractive index with temperature. The temperature change of the refractive index of quartz is 21 × 10
^-6 [1 / ° C.], and other glass materials such as fluorite
It is larger than 3.4 × 10 ⁻⁶ [1 / ° C.]. For this reason, in the scan type semiconductor exposure apparatus, since the slit-shaped illumination is performed, the focus position changes between the scan direction and the slit direction during exposure, and so-called exposure astigmatism occurs. Would.

[0005] As a solution to the above problem, the present applicant has proposed two parallel flat plates for correcting astigmatism.
A method of tilting the optical axis in the opposite direction by the same amount has been proposed. Attempts to solve astigmatism due to exposure have been made from the design level. This is because, in the design stage, the light energy density incident on each position of each lens in the projection lens is calculated by simulation, and the temperature rise at each position of each lens is obtained from this value. The shape deformation and the index change at each position are determined, and the final optical performance change is determined from these results, and this is minimized at the design stage.

SUMMARY OF THE INVENTION An object of the present invention is to reduce the change in the optical performance of a projection optical system during scanning exposure by a simple configuration in an exposure apparatus and a device manufacturing method in view of the problems of the prior art. It is in.

[0007]

In order to achieve this object, an exposure apparatus according to the present invention projects a pattern of an original plate while scanning and moving an original plate and a substrate with respect to a slit-like illumination light and a projection optical system. In a scan type exposure apparatus that performs scan exposure on the substrate via an optical system, a shape and an illuminance distribution of the slit-shaped illumination light so that a change in optical performance of the projection optical system generated during the scan exposure is reduced. Are provided with a variable slit and an optical means for respectively setting That is, the shape and the illuminance distribution of the slit-shaped illumination light are set such that the temperature distribution in the light beam passage area of the specific lens in the projection optical system becomes uniform.

Further, according to the device manufacturing method of the present invention, the pattern of the original plate is placed on the substrate via the projection optical system while scanning and moving the original plate and the substrate with respect to the slit-shaped illumination light and the projection optical system. In a device manufacturing method having a step of scanning exposure, the shape and illuminance distribution of the slit-like illumination light are set such that a change in optical performance of the projection optical system occurring during the scan exposure is reduced. .

According to this, the shape and the illuminance distribution of the slit-shaped illumination light are set so that the change in the optical performance of the projection optical system that occurs during the scanning exposure is reduced. Without providing a mechanism, a change in the optical performance of the projection optical system that occurs during scan exposure is reduced by a variable slit and an optical unit such as a zoom lens that the conventional exposure apparatus has in the illumination optical system.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An exposure apparatus according to a preferred embodiment of the present invention is characterized in that data for setting the shape and illuminance distribution of the slit-like illumination light is used for performing the scan exposure. Data acquisition means for obtaining the illuminance of the original plate surface by the shape illumination light, the transmittance of the slit-shaped illumination light with respect to the original plate, the average diffraction rate of the slit-shaped illumination light by the material, or a combination thereof.

Alternatively, the degree of diffraction of the slit-like illumination light by the original plate in the scan direction when performing the scan exposure is provided on a substrate stage that holds and moves the substrate to perform the scan movement. A diffraction sensor for measuring, which has a slit having a length corresponding to the slit-shaped illumination light, and a means for detecting light on a plurality of lines parallel to the slit below the slit, and A data acquisition unit configured to acquire data for setting a shape and an illuminance distribution of the slit-shaped illumination light based on a measurement result of the diffraction sensor.

Further, there is provided means for driving the variable slit and the optical means based on the data obtained by the data acquisition means to set the shape and illuminance distribution of the slit-like illumination light.

The variable slit and the optical means are arranged so that the light energy density of the slit-shaped illumination light passing through the vicinity of the center of the optical axis of the projection optical system at the time of the scanning exposure is smaller than the portions on both sides thereof. By setting the shape and illuminance distribution of the slit-shaped illumination light,
The astigmatism of the projection optical system is reduced.

In the device manufacturing method according to a preferred embodiment of the present invention, the shape of the slit-like illumination light and the illuminance distribution are set by the slit-like illumination passing near the center of the optical axis of the projection optical system during the scan exposure. The operation is performed so that the light energy density of the light portion is smaller than that of the portions on both sides thereof. Then, after setting the shape and illuminance distribution of the slit-shaped illumination light and before performing actual exposure of the substrate, a transparent dummy original plate is used, and the slit-shaped illumination light is applied to the original plate to form the projection optical system. The energy distribution of the slit-like illumination light on the surface corresponding to the surface to be exposed under the system is measured, and the shape or the illuminance distribution of the slit-like illumination light is finely adjusted as necessary based on the result. Hereinafter, embodiments of the present invention will be described more specifically through examples.

[0015]

FIG. 1 is an overall view of a semiconductor exposure apparatus according to one embodiment of the present invention. In the figure, 1 is an i-line lamp having a spectral output characteristic as shown in FIG. 4, 2 is a lighting device which is a power source of the i-line lamp 1, and 3 is a device for collecting a light beam of the discharge lamp 1. An elliptical mirror, 4 a closing plate for blocking a light beam while the semiconductor exposure apparatus is stopped, 5 a motor for driving the closing plate 4, 6 a middle band i-line filter of about several tens nm, and 7 a normal exposure. A high-speed exposure shutter for opening and closing each shot during the operation, 8 is an arc monitor imaging lens, 9 to 12 are half mirrors, 13 is a mirror,
Reference numerals 4 and 15 denote a gorge band i-line filter, 16 a middle band i-line filter, 17 a gorge band g-line filter, and 18 an elliptical mirror 3.
And a broadband filter 19 having a spectral transmittance substantially equal to the spectral reflectance of the CCD, and a CCD camera 19 for measuring the arc shape. 20 to 23 are gorge band i-line filters 1 respectively.
5, Middle band i-line filter 16, Gorge band g-line filter 1
7. Photodetectors for measuring the light energy transmitted through the broadband filter 18, which are referred to as a gorge band i-line detector, a middle band i-line detector, a gorge band g-line detector, and a broadband detector, respectively. I do. 24 is a photodetector for measuring the reflected light from the high-speed exposure shutter 7, and 25 is an element 1 to 24
Is a lamp house holding the inside.

Reference numeral 30 denotes a first zoom lens for forming an image of the arc shape of the i-line lamp 1 at an optimum size on the front end of the fly's eye 34, 31 denotes a motor for driving the zoom lens 30, and 32 denotes a motor. Finally, an i-band filter having a bandwidth of several nm that determines the exposure wavelength is provided with a mirror 33, a mirror 3,
4 is a fly's eye, 35 is an aperture for setting the sigma value of the illumination system, 36 is a second zoom lens for adjusting the illuminance distribution of the central portion and the peripheral portion on the reticle surface, and 37 is a second zoom lens.
A motor for driving the zoom lens 36;
About 1% of the light beam from the zoom lens 36 is
Reference numeral 9 denotes a parallel flat plate, 39 denotes a reticle surface illuminance detector arranged at a position conjugate with the center of the reticle surface, and 40 denotes a condensing lens for collecting light reflected from the reticle surface.
1 is a reticle reflected light detector for measuring the reticle reflected light condensed by the condenser lens 40, and 42 is an arrow 5
A masking blade movable in seven directions to limit the exposure area on the reticle in the scanning direction; 43 is a slit for forming a slit-like exposure area on the reticle;
4 and 46 are condenser lenses, and 45 is a mirror.

Reference numeral 47 denotes a microscope for measuring a pattern image on the reticle surface and the wafer surface, which is capable of retracting and moving outside the exposure light beam position. Where 4
8 is an imaging lens, and 49 is a CCD camera. 50 is a reticle, 51 is a dummy reticle having the same thickness as the reticle,
Reference numeral 52 denotes a reticle stage on which the reticle 50 and the dummy reticle 51 are mounted and which can scan in the direction of arrow 59. Numeral 60 designates the pattern in the reticle 50 as the wafer 6
1, a projection lens for reducing and projecting on the upper surface position, 61 a wafer, 62 a wafer chuck for holding the wafer by vacuum suction, and 63 a wafer chuck 62 driven in the vertical and tilt directions to move the upper surface of the wafer 61 Projection lens 6
ΘZ stage for matching with 0 image plane, 64 is θZ
Illuminance unevenness measuring instrument mountable on stage 63, 65 is a reference mark block mounted on θZ stage 63, 66 is a reticle diffracted light sensor mounted on θZ stage 63, 67 scans θZ stage 63 The wafer stage is movable in a direction (direction of an arrow 58) and in a direction perpendicular to the scanning direction.

Reference numeral 70 denotes an image processing device for measuring the arc shape of the i-ray lamp 1, 71 denotes an illumination system control unit, 72 denotes a general control unit of the semiconductor exposure apparatus, and 73 denotes a drive from the general control unit 72 of the semiconductor exposure device. Reticle stage 5 upon receiving command
2, a driver unit for driving the θZ stage 63 and the wafer stage 67; 74, an image processing device for measuring pattern images on the reticle surface and the wafer surface; and 75, a console as an operation unit of the semiconductor exposure apparatus.

FIG. 2 is a detailed view of the high-speed exposure shutter 7. In the figure, reference numeral 80 denotes a shutter blade made of a conductive metal material for cutting off and opening an exposure light beam by rotational driving; 81, a rotating shaft of the shutter blade 80;
(Shaded area) is an exposure light flux, 83 is an AC servomotor for rotating and driving the shutter blade 80, 84 is a motor fixing plate, and 85 and 86 are conductive metal disposed so as to sandwich the shutter blade 80. Material shielding plate, 87, 8
Numerals 8 and 89 are spacers for electrically insulating and holding the shielding plates 85 and 86 from the motor fixing plate 84, and 90 is a non-contact type thermometer.

FIG. 3 is a detailed view of the variable slit section 43. 100a to 100k and 101a to 101k are upper slit plates and lower slit plates that can be driven in the directions of arrows, 102a to 102k and 103a to 103k are guide portions of the slit plates, 104a to 104k and 1
Reference numerals 05a to 105k denote rotatable projections that move integrally with the slit plate, and reference numerals 106 and 107 denote spring plates that penetrate the rotatable projection and connect the slits.
Reference numerals 13 and 120 to 123 denote motors for driving a specific slit plate.

FIG. 4 is a graph showing the spectral output of the i-line lamp 1. In the present embodiment, in the spectral output of FIG.
Only the illustrated i-line portion near m is extracted by the gorge band i-line filter 32 and used. It should be noted that the spectral output near 436 nm shown in FIG.

FIG. 5 is a graph showing the spectral reflectance of the elliptical mirror 3. The elliptical mirror 3 has such a characteristic that it reflects only a light beam of about 320 nm to 400 nm.

The dashed line and the solid line in FIG. 6 are the cut characteristics of the middle band i-line filter 6 and the gorge band i-line filter 32, respectively. The characteristics are expanded by several tens of nm.

FIG. 7 is a perspective view showing the reticle diffraction optical sensor 66. Reference numeral 130 denotes a slit plate that can be driven by the θZ stage 63 on the image plane of the projection lens 60, and reference numeral 131 denotes a width 0 having substantially the same length as the exposure slit. Slits of about 0.3 mm and 132 to 136 are photodetectors for detecting reticle diffracted light.

FIG. 8 is a graph showing the relationship between the input power and the purity of a general i-line lamp. As shown in FIG.
The purity of a wire lamp decreases as the input power is increased.

FIG. 9A shows the illuminance distribution in the slit of the conventional semiconductor exposure apparatus. Ideally, the illuminance distributions in the scanning direction at all positions in the slit direction are all the same (FIG. 9A). (The shapes of the hatched portions Sa, Sb, Sc are all the same.)

FIG. 9B shows the illuminance distribution in the slit in the present embodiment, in which the second zoom lens 36 and the variable slit 43 reduce exposure astigmatism generated during exposure in the projection lens 60. The slit shape and the illuminance distribution required for the illumination can be formed.

FIGS. 10A and 10B show an i-line lamp 1.
In the illumination system of this embodiment, the i-line intensity distribution in the radial direction shown in FIG. 10A is projected by the zoom lens 30 on the incident side of the fly's eye 34. It has become so.

The semiconductor exposure apparatus according to the present embodiment is obtained by adding the following functions to the conventional semiconductor exposure apparatus. A. Abnormality detection of i-line lamp B. B. Arc shape correction function for i-line lamp D. Improvement of durability of i-line filter and high-speed exposure shutter E. Purity control of i-line lamp F. Detection of reflectance of exposure shutter blade G. Detection of deformation of exposure shutter blade Astigmatism reduction High precision integrated exposure control

The following is a description of each function. A. As shown in FIG. 1, the semiconductor exposure apparatus according to the present embodiment includes a gorge band i-ray detector 20 and a gorge band g-line detector 22 in a lamp house 25, and controls the illumination system. CP inside unit 71
By the operation of U (not shown), after the i-line lamp 1 is turned on,
After the discharge of the i-line lamp 1 is stabilized, the analog signal output of each detector is taken in every several mSec, digitized by an AD converter (not shown), and stored in a memory (not shown).
And stored as measurement data. In parallel with the above operation, the CPU constantly makes the following determination on the measurement data of each detector stored in the memory.

Whether the measurement data of each detector is within a predetermined allowable range, whether the fluctuation of the measurement data of each detector is within a predetermined allowable range, or whether the ratio of the measurement data of each detector is within a predetermined allowable range As a result of the above confirmation, when the CPU confirms the occurrence of the abnormality, the CPU immediately issues an instruction to turn off the i-line lamp 1 to the lighting device 2 and notifies the overall control unit 72 of the abnormality. When receiving the abnormality notification, the overall control unit 72 stops the operation of the apparatus, and performs an alarm and a display. The above operation eliminates the possibility of continuing an incomplete exposure process, and
Accidents such as the rupture of the wire lamp 1 can also be avoided.

B. Arc shape correction function of i-line lamp 1 A conventional semiconductor exposure apparatus has a variable aperture 35 whose aperture diameter can be changed inside its illumination system, similarly to the semiconductor exposure apparatus of the present embodiment. The arc of the i-line lamp 1 is projected by the zoom lens 30 to an optimum size on a part of the fly's eye 34 corresponding to the size. However, the arc shape and size of the i-line lamp 1 as represented in FIGS. 10A and 10B are not always constant due to differences between lamp makers, parts (manufacturing errors), and input power differences. In other words, it cannot be said that the conventional method always uses the light flux of the i-ray lamp 1 effectively and stably.

Therefore, in the semiconductor exposure apparatus of this embodiment,
As shown in FIG. 1, the CCD camera 19 is connected to the lamp house 2.
5 so that the arc shape of the i-line lamp 1 can be measured from the horizontal direction. After the i-line lamp 1 is turned on, the discharge is stabilized and the arc shape and the size are measured. . This actual measurement is performed by the image processing device 70, and the image processing device 70
When input from the CD camera 19, the position of the brightest point in this image is specified, and the horizontal intensity distribution at this position is determined. This intensity distribution has a shape as shown in FIG. Next, the image processing device 70 obtains a half-value width (half-width of the peak) of the intensity distribution and sends it to the illumination system control unit 71 as an arc radius value. Lighting system controller 7
When the CPU (not shown) receives the above arc radius value, it compares the arc radius value with the arc radius value of the reference i-line lamp. Of the zoom lens 30 so as to be projected on the incident portion of the zoom lens 30.

Further, the semiconductor exposure apparatus of the present embodiment always performs the above operation, and automatically adjusts the optimum power even when the input power to the i-line lamp 1 changes and the arc shape changes in the constant illuminance mode or the like. An arc shape is projected onto the entrance of the fly's eye 34.

C. 4. Improving the durability of the gorge band i-line filter and the high-speed exposure shutter In the semiconductor exposure apparatus of this embodiment, the actual exposure light
5 from the luminous flux of the i-ray lamp 1 having the spectral output characteristic of FIG.
Elliptical mirror 3 having a long wavelength cut characteristic as shown in FIG.
The light flux in the range of 320 to 400 nm is extracted using, and the light flux having a width of several tens of nm near the i-line is extracted by the middle band i-line filter 6 having the characteristics indicated by the dashed line in FIG. A luminous flux having a width of several nm near the i-line is extracted by the gorge band i-line filter 32 having the characteristic indicated by the solid line. For this reason, only the luminous flux in the wavelength band very close to the actual exposure light is emitted from the shutter blade 80 or the gorge band i.
The light enters the line filter 32.

D. i-line Lamp Purity Management In the semiconductor exposure apparatus of the present embodiment, the power control method of the i-line lamp
From 5, the setting can be made for each job. The specific power control method is as follows.

1. Constant input mode As in the conventional constant input mode, the input power to the i-line lamp 1 is specified. Although the purity is almost constant, the purity measurement and the like are not performed.

2. Constant illuminance mode Specify the image plane illuminance as in the conventional constant illuminance mode. However, since the input power to the i-line lamp 1 is controlled so that the illuminance is constant, the purity changes. The timing of changing the input power can be specified for each wafer or each job.

3. Constant purity mode This is a mode added in this embodiment, in which the purity of the i-line lamp 1 is specified. The specified power is maintained by controlling the input power by measuring the purity. The timing of changing the input power can be specified for each wafer or each job.

The above-mentioned “3. Constant purity mode” added in this embodiment will be described below. In the semiconductor exposure apparatus of this embodiment, as shown in FIG.
Middle band i-ray detector 21 for measuring the luminous flux of the order, and gorge band i-ray detector 20 for measuring the luminous flux of the i-line wavelength ± several nm
After the i-line lamp 1 is turned on and the discharge of the i-line lamp 1 is stabilized by the operation of the CPU (not shown) inside the illumination system control unit 71, the analog signal of each detector is The output is taken in every several mSec, digitized by an AD converter (not shown), and then the ratio calculation of the measurement data of each detector, that is, the purity is calculated. If the purity calculation result exceeds the allowable range with respect to the predetermined purity, the target purity is achieved by controlling the input power to the i-line lamp 1 within a range not exceeding the input power allowable range at the designated timing. Like that.

If the input power for achieving the specified purity exceeds the allowable input power range, the overall control unit 7
2 is notified that the exposure operation cannot be continued. When receiving the notification, the overall control unit 72 stops the operation of the apparatus, and performs an alarm and a display.

E. Detecting Reflectance of Exposure Shutter Blades In the semiconductor exposure apparatus of the present embodiment, exposure shutter protection measures such as those described in "C. Improvement of durability of i-band filter and high-speed exposure shutter" are implemented. It is not completely protected. because,
This is because impurities are mixed in the cooling air of the shutter blades 80, which may adhere to the surface of the shutter blades 80, reduce the surface reflectance of the shutter blades 80, and increase heat absorption.

Therefore, in this embodiment, as shown in FIG. 1, a broadband detector 23 for directly detecting a wavelength in the same band as a light beam condensed by the elliptical mirror 3, and a reflected light from the shutter blade 80 are detected. After the i-line lamp 1 is turned on and the discharge of the i-line lamp 1 is stabilized, when the shielding plate 4 is in the open state, the CP inside the illumination system control unit 71 is provided.
By the operation of U (not shown), the analog signal output of each detector is taken in every several mSec and digitized by an AD converter (not shown), and then the ratio calculation of the measurement data of each detector, that is, the shutter blade The calculation of the surface reflectance of No. 80 is performed. When the calculation result of the reflectance exceeds the allowable range with respect to the predetermined value, the lighting device 2
It issues a command to turn off the line lamp 1 and notifies the overall control unit 72 of this abnormality. When receiving the abnormality notification, the overall control unit 72 stops the operation of the apparatus, and performs an alarm and a display.

F. Detection of Deformation of Exposure Shutter Blade In the semiconductor exposure apparatus of this embodiment, the exposure shutter 7
In addition, in addition to the above countermeasures, contact detection between the shutter blade 80 and the surrounding members is performed. This is the shutter blade 8
The cause of the zero deformation is, besides the above-mentioned thermal deformation,
This is because erroneous maintenance of a user or a serviceman, a manufacturing error, mechanical damage during transportation, and the like are assumed.

In this embodiment, as shown in FIG. 2, the shutter blades 80 are made of a conductive metal material, and the shielding plates 85 and 86 around the openings are also made of a conductive metal material.
These are held in a state of being electrically insulated by insulating spacers 87, 88 and 89. On the other hand, a CPU (not shown) inside the illumination system control unit 71 includes a shutter blade 80
And constantly monitors the electrical contact of the shielding plates 85 and 86, and if an electrical contact is detected, immediately issues a command to the lighting device 2 to turn off the i-line lamp 1, and , The abnormality is notified to the overall control unit 72. When receiving the abnormality notification, the overall control unit 72 stops the operation of the apparatus, and performs an alarm and a display.

In this embodiment, since it is difficult to make an electrical connection directly with the shutter blade 80, the housing of the AC servomotor 83 shown in FIG.
To detect electrical contact between them.

G. Exposure Astigmatism Reduction The semiconductor exposure apparatus of the present embodiment has a function of reducing astigmatism generated during exposure. In the present embodiment, in the projection lens design stage, for each illumination mode, a slit shape and an illuminance distribution in the slit shape that minimize astigmatism due to exposure are obtained, and this is realized on a semiconductor exposure apparatus. is there.

FIG. 9A shows an example of the slit shape and the illuminance distribution in the slit shape of a conventional semiconductor exposure apparatus. As is clear from this figure, in the conventional semiconductor exposure apparatus, the illuminance distribution in the scanning direction at each point on the slit is made equal in order to make the integrated exposure amount in the slit direction uniform. That is, the shapes of the hatched portions Sa, Sb, and Sc in FIG. 9A are substantially the same. Further, in the conventional semiconductor exposure apparatus, when the illuminance distribution in the slit direction is not uniform, the slit width at each point on the slit is made variable in order to make the integrated exposure amount in the slit direction uniform. There is also a device devised so that the integrated amount of illuminance becomes the same. That is, in this case, the areas of the hatched portions Sa, Sb, and Sc in FIG. 9A are set to be substantially the same.

The semiconductor exposure apparatus of the present embodiment has a configuration similar to that of the above-described conventional example, but the purpose is completely different.
In the semiconductor exposure apparatus of the present embodiment, the slit shape and the illuminance distribution in the slit shape can be set arbitrarily, and this function reduces astigmatism and the like generated during exposure.

FIG. 9 (b) shows the state of a certain illumination mode.
An example of a slit shape optimal for reducing exposure astigmatism and an illuminance distribution in the slit shape will be described. In the slit illumination shown in the figure, in a lens close to a reticle or a wafer, the light energy density of a light beam passing near the center of the lens is reduced, and the temperature difference between the vicinity of the lens center and the peripheral portion does not increase in a region where the light beam passes. Like that. In addition, since the occurrence of the exposure astigmatism naturally depends on the reticle surface illuminance, the reticle transmittance, and the reticle average diffraction rate, in the present embodiment, these measurement results also indicate the illuminance in the slit shape and the slit shape. Used to determine distribution.
This is described below.

FIG. 7 shows a reticle diffraction sensor 66 mounted on the θZ stage 63 of the semiconductor exposure apparatus of this embodiment.
Is shown. The reticle diffraction sensor 66 measures the degree of reticle diffraction in the scanning direction. In the figure,
131 is a width 0.3 having a length equivalent to the exposure slit length.
The slits are about mm, and 132 to 136 are photodetectors. Here, as the number of fine patterns in the exposure pattern on the reticle increases, the incident light energy on the peripheral photodetector increases.

In the semiconductor exposure apparatus of the present embodiment, when the reticle 50 is first set on the reticle stage 52,
The measurement of the reticle average diffraction rate and the reticle transmittance is performed. This measurement is performed in the same illumination mode as the actual exposure (illumination system σ setting or modified illumination). At this time, the reticle diffraction sensor 66 stops at almost the center position of the exposure light beam, and integrates and measures the light energy incident while the reticle 50 is scanning. From the ratio of the integral measurement values of the sensors 132 to 136 of the reticle diffraction sensor 66, the set average reticle diffraction index is calculated.

During the measurement, the reticle surface illuminance detector 39 in the illumination system also performs integral measurement, and the sum of the integrated outputs of the sensors 132 to 136 of the reticle diffraction sensor 66 and the reticle surface illuminance detector 39 The reticle transmittance is also calculated from the ratio of the integral measurement values of. By the above measurement,
The reticle average diffraction rate and the reticle transmittance are determined. In the semiconductor exposure apparatus of this embodiment, the reticle surface illuminance is also measured by the reticle surface illuminance detector 39 immediately before the actual wafer exposure operation is started.

By the above operation, the set reticle 5
Since the reticle average diffraction index and reticle transmittance of 0 and the reticle surface illuminance in the currently set illumination mode are known, it is possible to calculate the slit shape and the illuminance distribution in the slit shape to minimize exposure astigmatism. Becomes In addition,
Since the amount of calculation for this determination is enormous, in the semiconductor exposure apparatus of this embodiment, the reticle average diffraction index calculated for each illumination mode at the design stage is stored in a memory in the main body control unit 72. Reticle transmittance, reticle surface illuminance, and representative data of the optimal slit shape and illuminance distribution in the slit shape are prepared in advance, and interpolation calculation is performed from the measured values of the reticle average diffraction rate, reticle transmittance, and reticle surface illuminance described above. Thus, the optimum slit shape and the illuminance distribution in the slit shape can be easily obtained.

When the optimum slit shape and the illuminance distribution in the slit shape are determined, these data are sent from the main body control unit 72 to the illumination system control unit 71, and the illumination system control unit 71 43 motors 110 to 11
By driving 3 and 120 to 123, an optimum slit shape is realized, and by driving the motor 37 of the second zoom lens 36, an optimum illuminance distribution in the slit shape is realized.

After the above operation, the semiconductor exposure apparatus of this embodiment
By moving the reticle stage 52, the transparent dummy reticle 51 is moved to the illumination area, and the optimal slit shape and the illuminance distribution in the slit shape are measured using the illuminance unevenness measuring device 64. The illuminance unevenness measuring device 64 is a linear CCD sensor having a long measurement range in the scanning direction, and moves it to an image plane position to measure the light energy distribution of one point on the slit in the scanning direction. Thereafter, the above measurement is performed at a plurality of points on the slit, and it is confirmed that the optimum value is realized.
If there is an error, fine adjustment of the variable slit 43 and the second zoom lens 36 is performed. Of course,
In order to make the integrated exposure amount in the slit direction uniform, the light energy distribution in the scan direction realized here should have the same value at any slit position when integrated in the scan direction.

When the above setting is completed, the semiconductor exposure apparatus of this embodiment returns the reticle stage 52 to the scan start position, and executes the following "H. High-precision integrated exposure amount control".
Move to reticle reflectivity measurement for

In this embodiment, in order to further minimize the change in exposure astigmatism, the total light energy incident on the projection lens 60 is determined by the output value of the photodetector 39 and the reticle transmittance even during exposure. , And fine adjustment of the optimum slit illumination shape and light energy distribution is automatically performed during exposure. Further, in the semiconductor exposure apparatus of the present embodiment, the microscope 47 shown in FIG. 1 is inserted into the exposure area at regular intervals, and the vertical and horizontal patterns on the reference mark block mounted on the θZ stage 63 are read by a CCD camera. Measurement is made at 49 so that it can be confirmed that the exposure astigmatism is surely within an allowable range.

H. High Accuracy Integrated Exposure Amount Control In the semiconductor exposure apparatus of the present embodiment, after determining the slit shape and the illuminance distribution in the slit shape for “G. Enter the reticle reflection measurement necessary to perform The reticle reflection measurement and the actual exposure operation will be described below.

(1) The illumination system control unit 71 transmits a command power to the i-line lamp 1 to the lighting device 2, and the lighting device 2 supplies the command power to the i-line lamp 1.

(2) Next, the reticle stage 52 is moved to the scan start position, and the measured value of the reticle surface illuminance detector 39 at this time is stored as a reference illuminance. When the reticle stage 52 is at the scan start position, the luminous flux from the illumination system does not return to the illumination system. That is, the reticle reflected light has not returned to the reticle surface illuminance detector 39 at all.

(3) The reticle stage 52 scans the entire exposure area at a speed sufficiently slower than that during the normal exposure, and the measured value of the reticle surface illuminance detector 39 for each reticle position is stored in the illumination system controller 71. In the memory.

(4) After the measurement, the CPU in the illumination system controller 71 subtracts the measurement value measured in (2) from the measurement value of the reticle surface illuminance detector 39 at each position of the reticle. This is stored in a memory for each reticle position as a reticle reflection measurement value.

(5) After the above measurement, the semiconductor exposure apparatus of this embodiment starts an actual wafer processing operation. In the actual wafer processing, first, in parallel with the loading of the wafer, the above (2)
, The current reticle surface illuminance is measured, and from this reticle surface illuminance, the scan speed required to achieve the target exposure amount is determined. Further, the ratio of the reticle surface illuminance to the reference illuminance obtained in the above (2) is calculated, and from this ratio, the reticle reflection measurement value obtained in the above (4) is corrected and calculated, and the current reticle reflection measurement value Is stored in the memory for each position of the reticle.

(6) After the above operation, the semiconductor exposure apparatus of the present embodiment executes pre-alignment measurement, fine alignment measurement, focus measurement, etc., and then moves the reticle 50 and wafer 61 at the same speed as the reduction ratio of the projection system 60. As shown by arrows 59 and 58, a scan exposure operation for transferring the pattern on the entire surface of the reticle 50 to one chip area on the wafer 61 while scanning in the opposite directions is started.

(7) The high-speed exposure shutter 7 is opened when the scan exposure operation starts and each stage comes immediately before the exposure area.

(8) When the high-speed exposure shutter 7 is opened, the reticle surface illuminance detector 39 can measure the reticle surface illuminance. Here, in the semiconductor exposure apparatus of the present embodiment,
The measured value of the reticle surface illuminance detector 39 is not regarded as the reticle surface illuminance, and the reticle surface illuminance is a value obtained by subtracting the reticle reflection measurement value for each current reticle position obtained in (5) from the measured value. The power control of the lighting device 2 is performed so that this value always becomes the same as the current reticle surface illuminance stored in the above (5). This operation continues during the scan exposure operation.

(9) When the scan exposure operation is completed, the power command value for the lighting device 2 is fixed to the input power command value specified in (1), and the high-speed exposure shutter 7 is closed.

The exposure operation for one shot is completed by the above operation, and the same operation is repeated to complete the scan exposure on the entire surface of the wafer.

<Embodiment of Device Manufacturing Method> Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described. FIG. 11 shows a flow of manufacturing micro devices (semiconductor chips such as ICs and LSIs, liquid crystal panels, CCDs, thin-film magnetic heads, micromachines, etc.). Step 1
In (Circuit Design), a device pattern is designed. Step 2 is a process for making a mask on the basis of the designed pattern. Step 3 (wafer manufacturing)
Then, a wafer is manufactured using a material such as silicon or glass. Step 4 (wafer process) is called a pre-process,
An actual circuit is formed on the wafer by lithography using the prepared mask and wafer. The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in step 4, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). including. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 12 shows a detailed flow of the wafer process (step 4). Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. In step 15 (resist processing), a resist is applied to the wafer. Step 16 (exposure) uses the above-described exposure apparatus or exposure method to align and print the circuit pattern of the mask on a plurality of shot areas of the wafer. Step 17 (development) develops the exposed wafer. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the production method of this embodiment, a large-sized device, which has been conventionally difficult to produce, can be produced at low cost.

[Modifications of the Embodiments] The present invention is not limited to the above-described embodiments, but can be implemented with appropriate modifications. For example, in the semiconductor exposure apparatus of the above-described embodiment, the illuminance distribution in the slits at the center and the periphery is controlled by the zoom lens. Instead, the illuminance distribution can be independently controlled in the slit direction and the scan direction. It is also possible to further reduce astigmatism by using a mechanism. Further, by inserting a filter having a transmittance different from place to place at a position substantially conjugate with the reticle, it is possible to further reduce astigmatism.

In the above embodiment, the case where the present invention is applied to a scan type semiconductor exposure apparatus using an i-line lamp as a light source has been described. However, the present invention is not limited to this.
The present invention can be easily applied to a scan type semiconductor exposure apparatus using another continuous light source, a scan type semiconductor exposure apparatus using a pulsed light source such as an excimer laser, and a stepper type semiconductor exposure apparatus.

Further, in the above embodiment, the exposure astigmatism has been described. However, in the simulation at the stage of designing the projection lens, the astigmatism other than the astigmatism or the astigmatism and other aberrations are reduced. The same thing as the invention can be carried out.

[0076]

As described above, according to the present invention, it is possible to reduce exposure astigmatism and the like without providing a special mechanism for exposure astigmatism in the projection optical system.

Further, a conventional scanning type exposure apparatus is
Exposure astigmatism and the like can be reduced by making the best use of a variable slit and a zoom lens provided for the purpose of correcting illuminance unevenness.

[Brief description of the drawings]

FIG. 1 is an overall view of a semiconductor exposure apparatus according to one embodiment of the present invention.

FIG. 2 is a detailed view of a high-speed exposure shutter in the apparatus of FIG.

FIG. 3 is a detailed view of a variable slit unit in the apparatus of FIG.

FIG. 4 is a graph showing a spectral output of an i-line lamp in the apparatus of FIG.

FIG. 5 is a graph showing the spectral reflectance of an elliptical mirror in the apparatus of FIG.

6 is a graph showing cut characteristics of a middle band i-line filter and a gorge band i-line filter in the apparatus of FIG. 1;

7 is a perspective view showing a reticle diffraction sensor mounted on a θZ stage in the apparatus shown in FIG.

FIG. 8 is a graph showing a relationship between input power of an i-line lamp and purity.

FIG. 9 is an explanatory diagram of the illuminance distribution in the slit in the conventional and the semiconductor exposure apparatus of FIG. 1;

10 is a graph showing the i-line intensity distribution of the i-line lamp in the radial direction and the electrode direction in the apparatus of FIG.

FIG. 11 is a flowchart illustrating a device manufacturing method that can use the exposure apparatus of the present invention.

FIG. 12 is a detailed flowchart of a wafer process in FIG. 11;

FIG. 13 is an explanatory view of a conventional semiconductor exposure apparatus.

[Explanation of symbols]

1: i-line lamp, 2: lighting device, 3: elliptical mirror, 4:
Blocking plate, 5: motor, 6: middle band i-line filter, 7: high-speed exposure shutter, 8: arc monitor imaging lens, 9-1
2: Half mirror, 13: Mirror, 14, 15: Gorge band i-line filter, 16: Middle band i-line filter, 17: Gorge band g-line filter, 18: Broad band filter, 19: CCD
Camera, 20: Gorge band i-ray detector, 21: Mid band i-ray detector, 22: Gorge band g-ray detector, 23: Broad band detector,
24: photodetector, 25: lamp house, 30: first zoom lens, 31: motor, 32: gorge band i-line filter,
33: mirror, 34: fly-eye, 35: aperture, 36: second zoom lens, 37: motor, 38: parallel flat plate, 3
9: reticle surface illuminance detector, 40: condenser lens, 41:
Reticle reflected light detector, 42: masking blade, 4
3: slit, 44, 46: condenser lens, 45:
Mirror, 47: microscope, 48: imaging lens, 49: CC
D camera, 50: reticle, 51: dummy reticle, 5
2: reticle stage, 60: projection lens, 61: wafer, 62: wafer chuck, 63: θZ stage, 6
4: Illuminance unevenness measuring instrument, 65: Reference mark block, 6
6: reticle diffraction light sensor, 67: wafer stage, 7
0: Image processing device, 71: Illumination control unit, 72: Overall control unit, 73: Driver unit, 74: Image processing device, 75:
Console, 80: shutter blade, 81: rotating shaft of shutter blade, 82 (shaded portion): exposure light beam, 83: AC servomotor, 84: motor fixing plate, 85, 86: shielding plate,
87 to 89: spacer, 90: non-contact type thermometer, 100
a to 100k: upper slit plate, 101a to 101k:
Lower slit plate, 102a-102k, 103a-10
3k: guide part, 104a-104k, 105a-10
5k: rotatable projection, 106, 107: spring plate, 11
0 to 113, 120 to 123: motor, 200: pattern, 201: slit illumination.

Claims (8)

[Claims] 1. A scanning type exposure apparatus for scanning and exposing a pattern of an original onto a substrate via a projection optical system while scanning and moving an original and a substrate with respect to a slit-shaped illumination light and a projection optical system. A variable slit and an optical unit that respectively set a shape and an illuminance distribution of the slit-shaped illumination light so that a change in optical performance of the projection optical system that occurs during the scan exposure is reduced. Exposure equipment. 2. Data for setting the shape and illuminance distribution of the slit-like illumination light, wherein the illuminance of the original plate surface by the slit-like illumination light and the slit-like illumination when performing the scan exposure 2. The exposure apparatus according to claim 1, further comprising a data acquisition unit configured to obtain a transmittance of the light with respect to the original plate, an average diffraction ratio of the slit illumination light by the original plate, or a combination thereof. 3. The degree of diffraction of the slit-like illumination light by the original plate in a scanning direction when performing the scan exposure is provided on a substrate stage that holds and moves the substrate to perform the scan movement. A diffraction sensor for measuring, which has a slit having a length corresponding to the slit-shaped illumination light, and a means for detecting light on a plurality of lines parallel to the slit below the slit, and 2. The exposure apparatus according to claim 1, further comprising a data acquisition unit configured to acquire data for setting a shape and an illuminance distribution of the slit-shaped illumination light based on a measurement result of the diffraction sensor. 3. 4. The apparatus according to claim 1, further comprising means for driving said variable slit and optical means based on the data obtained by said data acquisition means to set the shape and illuminance distribution of said slit-shaped illumination light. 4. The exposure apparatus according to 2 or 3. 5. The variable slit and the optical means such that the light energy density of a portion of the slit-shaped illumination light passing near the optical axis center of the projection optical system at the time of the scan exposure is smaller than portions on both sides thereof. The shape and the illuminance distribution of the slit-shaped illumination light are set, thereby reducing astigmatism of the projection optical system. Exposure equipment. 6. A device manufacturing method comprising: scanning and exposing a pattern of the original plate onto the substrate via the projection optical system while scanning and moving the original plate and the substrate with respect to the slit-shaped illumination light and the projection optical system. A method of setting the shape and illuminance distribution of the slit-shaped illumination light so that a change in optical performance of the projection optical system occurring during the scan exposure is reduced. 7. The setting of the shape and illuminance distribution of the slit-like illumination light is such that the light energy density of the slit-like illumination light passing through the vicinity of the center of the optical axis of the projection optical system at the time of the scan exposure is adjusted on both sides thereof. 7. The device manufacturing method according to claim 6, wherein the process is performed so as to be smaller than a portion. 8. After setting the shape and illuminance distribution of the slit-like illumination light, and before performing actual exposure of the substrate, a transparent dummy original plate is used, and the slit-like illumination light is applied to this. Measure the energy distribution of the slit-like illumination light on a surface corresponding to the surface to be exposed under the projection optical system,
8. The device manufacturing method according to claim 6, wherein the shape or illuminance distribution of the slit-shaped illumination light is finely adjusted as needed based on the result.