JPH07153683A - Aligner - Google Patents

Abstract

PURPOSE:To execute projection with a uniform light intensity onto a photosensitive base in an aligner wherein luminous fluxes from discrete illuminating optical systems in a plurality are applied to a plurality of areas to be illuminated on a mask and images of these areas are projected onto the photosensitive base through a plurality of projecting optical systems. CONSTITUTION:The intensities of luminous fluxes (L) from illuminating optical systems (LO1 to LO5) disposed for a plurality of projecting optical systems (PL1 to PL5) respectively are detected and a control is made so that the intensities of other illuminating optical systems be in accord with the intensity of the illuminating optical system from which the lowest intensity is obtained. Since the light intensity of the whole projecting area can be detected two- dimensionally by a second light intensity detecting means, besides, the control is executed by taking the nonuniformity of the light intensity remaining in the discrete projecting area into account.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus, for example, for manufacturing a semiconductor element or a liquid crystal display substrate, and particularly applicable to an apparatus having a plurality of illumination optical systems.

[0002]

2. Description of the Related Art In recent years, liquid crystal display substrates have been widely used as display elements for personal computers, televisions and the like. This liquid crystal display substrate is formed by patterning a transparent thin film electrode on a glass substrate into a desired shape by a photolithographic method. As an apparatus for this lithography, a projection exposure apparatus is used which exposes an original pattern formed on a mask onto a photoresist layer on a glass substrate via a projection optical system.

Recently, there is a demand for a larger area of the liquid crystal display substrate, and accordingly, the projection exposure apparatus is also required to expand the exposure area. As a means for enlarging this exposure area, a scanning type exposure apparatus provided with a plurality of projection optical systems can be considered. That is, a plurality of illumination optical systems are provided,
The mask is illuminated with the light flux emitted from each illumination optical system, and the image of the illuminated mask is projected onto the projection area on the glass substrate through each of the plurality of projection optical systems.

Further, after the light flux emitted from the light source is made uniform in the amount of light through an optical system including a fly-eye lens and the like, it is shaped into a desired shape by a field stop and illuminated on the pattern surface of the mask. To do. A plurality of optical systems (illumination optical systems) having such a configuration are arranged, and different small areas (illumination areas) on the mask are illuminated by the light beams emitted from the plurality of illumination optical systems, respectively. The light flux transmitted through the mask forms a pattern image of the mask on different projection regions on the glass substrate via different projection optical systems. Then, by synchronously scanning the mask and the glass substrate with respect to the projection optical system, the entire surface of the pattern area on the mask is transferred onto the glass substrate.

[0005]

By the way, since the scanning type exposure apparatus described above has a plurality of illumination optical systems, it is necessary to make the intensity of the luminous flux emitted from each illumination optical system constant. Therefore, in the manufacturing stage of the device, the intensity of the light flux from each illumination optical system is adjusted to be constant by using an ND filter or the like. However, the state of deterioration of the brightness of the light source (lamp) due to the passage of time of use of the device differs from lamp to lamp, so that the intensity of the light flux is not constant during use of the device.

Further, when the lamps are replaced, the initial brightness differs from lamp to lamp, so that it becomes necessary to adjust the intensity of the luminous flux again. In order to facilitate this intensity adjustment, a detector is placed in each illumination optical system, and the applied voltage to each lamp is feedback-controlled so that the intensity of the luminous flux becomes an arbitrary reference value based on the signal obtained by the detector. It is possible to do it.

However, in general, there are variations in the luminance of the lamp due to manufacturing, and the luminance decreases depending on the usage time. Therefore, in this method, the minimum value of the variation and the minimum value of the luminance during the life time are set. It is necessary to use the above standard value. Therefore, there is a problem that the intensity of the luminous flux of each illumination optical system is always stable only at a low level, the exposure time increases, and the throughput of the apparatus decreases.

Further, the above-mentioned scanning type exposure apparatus is generally an apparatus that holds a mask and a glass substrate and moves in a uniaxial direction to perform exposure, and it is necessary to detect the light intensity on the glass substrate over the entire exposure light flux. Was difficult.

The present invention has been made in consideration of the above points, and irradiates a plurality of illuminated regions on a mask with light fluxes from a plurality of illumination optical systems, and images the plurality of illuminated regions. It is an object of the present invention to propose an exposure apparatus capable of projecting onto a photosensitive substrate with a uniform light intensity when projecting onto the photosensitive substrate via a plurality of projection optical systems.

[0010]

In order to solve such a problem, in the first invention, a plurality of illumination optical systems (LO1 to LO1
LO5) and its plurality of illumination optical systems (LO1 to LO5)
A plurality of projection optical systems (P
L1-PL5) and a plurality of illumination optical systems (LO1-LO5)
Luminous flux (L) from each of the LO5) is applied to a plurality of irradiated regions on the mask (9), and images of the plurality of irradiated regions are transmitted through a plurality of projection optical systems (PL1 to PL5) to a photosensitive substrate. (10) In an exposure apparatus for projecting light onto a plurality of illumination optical systems (LO1 to LO5), a plurality of light intensity detecting means (1) for detecting the intensity of the light flux (L) are provided.
1) and light intensity changing means (13, 13) for changing the intensity of the light flux (L) of each of the plurality of illumination optical systems (LO1 to LO5).
14 and 15) and the light intensity (P1 to P5) of the light flux (L) detected by each of the plurality of light intensity detecting means (11) so that the light intensity of the light flux (L) becomes constant. Control means (12) for controlling the changing means (13, 14, 15)
I decided to set and.

In the second invention, the control means (1
2) refers to the lowest value of the intensities (P1 to P5) of the light flux (L) detected by each of the plurality of light intensity detecting means (11) as a reference. Light intensity changing means (13, 1, 1)
4, 15) was controlled.

Further, in the third invention, second light intensity detecting means (16, 2) for detecting the intensity of each of the light fluxes (L) emitted from the plurality of illumination optical systems (LO1 to LO5).
2) is provided.

In the fourth invention, the control means (1
2) is the detection result of the second light intensity detecting means (16) (P
O) and the respective detection results (P1 to P5) of the plurality of light intensity detecting means (11) based on the light intensity detecting means (1).
The detection result (P1 to P5) of 1) was corrected.

In the fifth aspect of the invention, the light intensity changing means (13, 14, 15) includes illumination optical systems (LO1 to LO).
A member (14) having a transmittance lower than that of the optical element constituting (5)
Included.

In the sixth invention, the second light intensity detecting means (22) is a stage (2) which moves in a predetermined direction.
0) is placed on a moving means (21) which is placed on and moves in a direction orthogonal to the moving direction of the stage (20),
The light intensity of each light flux that has moved through the same plane as the surface of the photosensitive substrate (10) and passed through the plurality of projection optical systems (PL1 to PL5) is detected.

In the seventh invention, the control means (2
5) is a second light intensity detecting means (2) prior to exposure.
Based on the detection data (P10) by 2), the light intensity changing means (26) of each illumination optical system (LO1 to LO5) is controlled to make the light intensity of each light flux on the photosensitive substrate surface (10) uniform. During alignment and exposure, the light intensity changing means (26) is controlled to control the light intensity detecting means (1) of the respective illumination optical systems (LO1 to LO5).
The light intensity of each light flux (L) uniformly aligned in 1) is maintained.

[0017]

Function: The intensity of the illumination optical system that detects the intensity of the luminous flux (L) from the illumination optical systems (LO1 to LO5) arranged in each of the plurality of projection optical systems (PL1 to PL5) and obtains the lowest intensity. By controlling so that the intensities of the other illumination optical systems are adjusted to all the illumination optical systems (LO) regardless of variations in the initial luminance of the light source and luminance deterioration due to use.
1 to LO5) can provide uniform strength.

Since the second light intensity detecting means (22) can two-dimensionally detect the light intensity of all projection areas (PA1 to PA5), the light intensity remaining in each projection area is not detected. By controlling the uniformity by taking it into account, a more uniform exposure surface illuminance can be obtained, and the illumination optical system (L
The exposure surface illuminance is kept constant irrespective of the deterioration of the light source of O1 to LO5) and the exposure amount control can be performed easily and accurately.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

(1) First Embodiment FIG. 1 shows the configuration of a first embodiment of an exposure apparatus according to the present invention, in which a light beam L emitted from a light source 1 such as an ultrahigh pressure mercury lamp.
Is a fly-eye lens 4 via an elliptic mirror 2 and a lens system 3.
Therefore, the strength is made uniform. Then, it is shaped into a desired shape by the field stop 7 via the half mirror 5 and the lens system 6, and an image of the field stop 7 is formed on the pattern surface of the mask 9 via the lens system 8.

A plurality of this illumination optical system (optical element from the light source 1 to the lens system 8 and referred to as LO1) are arranged (however, in the figure, only the one corresponding to the lens system 8 is shown and LO2 is shown respectively. Light beams emitted from each of the plurality of illumination optical systems LO1 to LO5 illuminate different small areas (illumination areas) on the mask 9, respectively. The plurality of light fluxes that have passed through the mask 9 are transmitted through different projection optical systems PL1 to PL5, respectively, and different pattern images corresponding to the illumination areas of the mask 9 are formed in different projection areas (indicated by PA1 to PA5 in FIG. 2) on the photosensitive substrate 10. Image.

In this case, the projection optical systems PL1 to PL5 are
Both are assumed to be an equal size erect system. As shown in FIG. 2, the projection area on the photosensitive substrate 10 is such that adjacent areas (for example, P
A1 and PA2, PA2 and PA3) are displaced by a predetermined amount in the X direction of the drawing, and the end portions of adjacent areas (in the drawing,
The portion indicated by the broken line) is arranged so as to overlap in the Y direction in the figure. Therefore, the plurality of projection optical systems PL1 to PL5 are also displaced by a predetermined amount in the X direction according to the arrangement of the projection areas PA1 to PA5, and are also arranged overlapping in the Y direction.

The arrangement of the plurality of illumination optical systems LO1 to LO5 is such that the illumination area on the mask 9 is the projection area PA1 described above.
~ PA5 are arranged so as to be the same arrangement. Then, the mask 9 and the photosensitive substrate 10 are synchronized with each other, and the projection optical systems PL1 to PL1 are arranged in the X direction (direction perpendicular to the paper surface in FIG. 1).
By scanning PL5, the entire surface of the pattern area on the mask 9 is transferred to the exposure area EA on the photosensitive substrate 10.

A half mirror 5 is provided in the optical path of each of the illumination optical systems LO1 to LO5, and a part of the light flux L is incident on the detector 11. The detector 11 constantly detects the intensity of the light flux L and inputs the obtained signals P1 to P5 to the signal processing device 12. The signal processing device 12 receives the signal P1.
To P5, the intensities of the luminous fluxes L of the illumination optical systems LO1 to LO5 are obtained, and the one showing the lowest value among these intensities is set as a reference value. Then, the voltage applied to the power supply 13 (or the power supply current) is feedback-controlled so that the intensity of the other light flux becomes equal to this reference value. The interval at which the signal processing device 12 processes the signals P1 to P5 can be arbitrarily set as needed.

By the way, when a part of the plurality of light sources 1 is replaced with a new one, the new light source has higher brightness than other light sources. In this case, it is impossible to control the intensity of each light flux to be constant only by controlling the applied voltage as described above. Yottte, the illumination optical system LO
The ND filters 14 are arranged in the respective optical paths of 1 to LO5 so as to be able to move forward and backward with respect to the light flux L, and the filter driving unit 15 is controlled by the signal from the signal processing device 12. A plurality of ND filters 14 having different transmittances may be prepared, and each ND filter 14 may be switched or used in combination.

In this embodiment, the detector 11 is
Illumination optical systems LO1 to LO5 and projection optical systems PL1 to PL5
Each illumination optical system LO including the transmittance of the optical elements that compose the
It is necessary to calibrate variations in the detection value of the detector 11 itself for each 1 to LO5. Therefore, the detector 16 is provided so that the light receiving surface is arranged in the same plane as the photosensitive substrate 10. Then, the detector 16 is connected to the projection areas PA1 to PL5 of the projection optical systems PL1 to PL5.
It is arranged in the PA 5 to detect the intensity of the luminous flux.

The obtained intensity signal PO is applied to the signal processor 12
The difference between the signal PO and the detection signals P1 to P5 of the detector 11 of each of the illumination optical systems LO1 to LO5 is used as the offset of each detector 11. This enables more accurate control of the intensity of the light flux. Also, ND filter 1
It is also possible to check the linearity of the detection signals P1 to P5 of the detector 11 by switching between 4 and 4.

(2) Second Embodiment FIG. 3 in which parts corresponding to those in FIG. 1 are assigned the same reference numerals shows the structure of a second embodiment of the exposure apparatus according to the present invention. In the case of this exposure apparatus, an exposure stage 20 that integrally holds the mask stage on which the mask 9 is placed and the substrate stage on which the photosensitive substrate 10 is placed is formed. As a result, the illumination optical systems LO1 to LO1 fixed by the fixing support portions (not shown), respectively.
After the mask 9 and the photosensitive substrate 10 are aligned with the LO5 and the projection optical systems PL1 to PL5 by an alignment system (not shown), the exposure stage 20 is integrally scanned and exposed while the mask 9 and the photosensitive substrate 10 are held. The mask image is transferred to the photosensitive substrate 10. At this time, the exposure amount is determined by the illumination light intensity on the photosensitive substrate 10 and the scanning speed of the exposure stage 20.

Further, in the exposure apparatus of this embodiment, the detection sensor drive section 21 having the drive axis (Y axis) orthogonal to the movement axis (X axis) of the exposure stage is arranged on the substrate stage of the exposure stage 20. , The detector 2 is mounted on the detection sensor driving unit 21 so as to be flush with the photosensitive substrate 10.
2 is placed. Then, prior to one or more exposures, the movement axis (X axis) of the exposure stage 20 and the drive axis (Y axis) of the detection sensor driving unit 21 are driven to move the detector 22 to the projection optical systems PL1 to PL5. Projection area PA1
Scanning under PA5, the illumination light intensity on the exposed surface is two-dimensionally measured and sent as light intensity data.

FIG. 4 shows an illumination light intensity control system according to the second embodiment, and based on the measured light intensity data P10 on the exposure surface, illumination optical systems LO1 to LO1 corresponding to the projection optical systems PL1 to P5, respectively. The light intensity of LO5 is detected by the detector 11 attached to the illumination optical systems LO1 to LO5 (P1 to P5), and the illumination light intensity control unit 26 is controlled to project the projection areas PA1 to PL5 of the projection optical systems PL1 to PL5. P
The illumination light intensity is set to be uniform in the entire exposure area including A5.

After the setting, the illumination light intensity of the exposure surface is measured and confirmed by the detector 22 again by the same procedure as described above. When the uniformity of the illumination light intensity falls within the standard by repeating this procedure, the measured value P1 of the detector 22 on the exposure surface at this time is obtained.
0 is stored in the storage circuit 27 as the exposure surface illuminance. On the other hand, at this time, the detector 11 of each of the illumination optical systems LO1 to LO5
The detected values P1 to P5 are stored in the storage circuit 28 at the same time.
At the time of actual exposure, the movement speed of the exposure stage 20 is controlled by the exposure stage control circuit 29 so that the exposure amount of the photosensitive substrate 10 becomes optimum with respect to the illuminance of the exposure surface stored in the storage circuit 27.

In parallel with this, the respective illumination optical systems LO1 to LO
The illumination light intensities of 5 are detected values P1 to P of the detector 11, respectively.
5 is controlled by the illumination light intensity control unit 26 so that the value 5 is maintained at the values PM1 to PM5 stored in the storage circuit 28. As a specific example of the illumination light intensity section 26, a zoom optical system, current control of a light source, position control of an ND filter whose transmittance changes in a tilted manner depending on the location, and the like are performed. In this way, the light intensity (illuminance) of the entire projection areas PA1 to PA5 can be kept uniform and constant.

According to the above construction, the entire projection area PA1.
Since the light intensity of the PA 5 can be detected two-dimensionally, a more uniform exposure surface illuminance can be obtained by calculating and controlling the non-uniformity of the light intensity remaining in each projection region. Further, the exposure surface illuminance is kept constant regardless of the deterioration of the light sources of the illumination optical systems LO1 to LO5, so that the exposure amount control becomes easy and accurate. Note that the exposure surface illuminance is reset by a predetermined number of times of exposure or time or illumination optical systems LO1 to LO.
This may be performed when the control of the illumination intensity control unit 26 becomes impossible due to deterioration of the light source of No. 5 or the like.

(3) Other Embodiments In the above embodiment, the projection areas PA1 to PA5 are provided.
So that the illumination optical system LO1 is arranged as shown in FIG.
-LO5 and projection optical systems PL1-PL5 are arranged, the illumination optical systems LO2, LO4 and the projection optical systems PL2, P4 that form the projection areas PA2, PA4 shown in FIG.
The configuration may be such that L4 is not provided. In this case, after the mask 9 and the photosensitive substrate 10 are scanned in the X direction, a predetermined amount of step is performed in the Y direction and scanning is performed again in the opposite direction to the X direction, so that the entire pattern area of the mask is transferred onto the photosensitive substrate. can do.

Further, although the projection optical systems PL1 to PL5 having the same magnification are used in the above-mentioned embodiments, a projection optical system having a predetermined magnification may be used, and a reflection system optics may be used instead of the refraction system. A system may be used. Further, although the aperture shape of the field stop is trapezoidal, the invention is not limited to this, and a field stop having a hexagonal aperture may be used, for example.

[0036]

As described above, according to the present invention, the intensity of the luminous flux from the illumination optical system disposed in each of the plurality of projection optical systems is detected, and the intensity of the illumination optical system that obtains the lowest intensity may be different from the intensity of the illumination optical system. By controlling so that the intensity of the illumination optical system is matched, it is possible to always obtain a uniform intensity in all the illumination optical systems regardless of variations in the initial luminance of the lamp and luminance deterioration due to use.

Further, unlike the conventional device, in which the minimum brightness during the life of the lamp is set as a reference value in advance, the reference value is set to a level higher than the minimum brightness, so that the brightness of the lamp is always set. It can be used effectively and avoids lowering the device throughput.

Further, since the light intensity of the entire exposure area can be detected two-dimensionally, the light intensity nonuniformity remaining in a single exposure area can be calculated and controlled to obtain a more uniform exposure surface illuminance. Can be obtained. Further, since the illuminance on the exposure surface is kept constant regardless of the deterioration of the light source of the illumination optical system, the exposure amount can be controlled easily and accurately.

[Brief description of drawings]

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

2 is a schematic diagram showing a projection area on a photosensitive substrate in the exposure apparatus of FIG.

FIG. 3 is a schematic perspective view showing a configuration of a second embodiment of the exposure apparatus according to the present invention.

4 is a schematic diagram for explaining a light amount control system in the exposure apparatus of FIG.

[Explanation of symbols]

1 ... Light source, 2 ... Elliptical mirror, 3, 6, 8 ... Lens system,
4 ... Fly-eye lens, 5 ... Half mirror, 7 ...
Field stop, 9 ... Mask, 10 ... Photosensitive substrate, 11 ...
Detector, 12 ... Signal processing device, 13 ... Power supply, 1
4 ... ND filter, 15 ... Filter drive unit, 16 ...
... detector, 20 ... exposure stage, 21 ... detection sensor drive section, 22 ... light intensity detection sensor, 25 ... signal processing circuit, 26 ... illumination intensity control section, 27, 28 ... storage circuit, 29 ... ... Exposure stage control circuit, LO1 to LO
5 ... Illumination optical system, PL1 to PL5 ... Projection optical system.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G03F 7/20 521 9122-2H 7352-4M H01L 21/30 518 (72) Inventor Tetsuo Kikuchi Tokyo 3 2-3 Marunouchi, Chiyoda-ku Nikon Corporation

Claims (7)

[Claims] 1. A mask having a plurality of illumination optical systems and a plurality of projection optical systems arranged corresponding to each of the plurality of illumination optical systems, and masking a light flux from each of the plurality of illumination optical systems. An exposure apparatus which irradiates a plurality of upper irradiation areas and projects images of the plurality of irradiation areas onto a photosensitive substrate through the plurality of projection optical systems, wherein each of the plurality of illumination optical systems is provided. Detected by the plurality of light intensity detecting means for detecting the intensity of the light flux, the light intensity changing means for changing the intensity of the light flux of each of the plurality of illumination optical systems, and the plurality of light intensity detecting means. An exposure apparatus comprising: a control unit that controls the light intensity changing unit so that the intensity of the light flux becomes constant according to the intensity of the light flux. 2. The control means is configured such that all of the plurality of light intensity detecting means have the lowest value with reference to the lowest value of the intensities of the luminous flux detected by each of the plurality of light intensity detecting means. The exposure apparatus according to claim 1, wherein the light intensity changing unit is controlled so that 3. The exposure apparatus according to claim 1, further comprising a second light intensity detecting means for detecting the intensity of each of the light beams emitted from the plurality of illumination optical systems. 4. The control means corrects the detection result of the light intensity detecting means based on the detection result of the second light intensity detecting means and the detection result of each of the plurality of light intensity detecting means. The exposure apparatus according to claim 3, wherein: 5. The exposure apparatus according to claim 1, wherein the illuminance changing unit includes a member having a lower transmittance than an optical element forming the illumination optical system. 6. The second light intensity detecting means is mounted on a stage that moves in a predetermined direction and is arranged in the moving means that moves in a direction orthogonal to the moving direction of the stage, The exposure apparatus according to claim 3, wherein the light intensity of each of the light fluxes that have moved through the same plane and passed through the plurality of projection optical systems is detected. 7. The control means controls the light intensity changing means of each of the illumination optical systems based on the detection data by the second light intensity detecting means prior to the exposure, and the photosensitive substrate surface. The light intensities of the respective light fluxes above are uniformly aligned, and at the time of exposure, the light intensity changing means is controlled to hold the light intensity of each light flux uniformly aligned by the light intensity detecting means of each illumination optical system. The exposure apparatus according to claim 6, wherein: