JP3339144B2 - Scanning exposure apparatus and exposure method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning exposure apparatus,
In particular, the present invention relates to an exposure apparatus suitable for exposing a large substrate such as a liquid crystal display panel.

[0002]

2. Description of the Related Art In recent years, liquid crystal display panels have been widely used in place of CRTs because of their remarkably improved display quality and the advantages of being thin and lightweight. In particular, the screen size of an active matrix type direct-view type liquid crystal panel is increasing, and the size of a glass substrate used for manufacturing the same is also increasing.

As an exposure apparatus for exposing such a large glass substrate, a so-called proximity system in which a mask and a substrate are brought close to each other to perform simultaneous exposure, and a refraction optical system having a large transfer area as a projection optical system having a large transfer area are used. A step-and-repeat method using, and a projection optical system as a reflection optical system of the same magnification, illuminating the mask with arc-shaped illumination light to form an image of this mask on the substrate in an arc shape, There is a mirror projection system that scans a projection optical system.

[0004]

When a large substrate is exposed by the proximity method, it is necessary to bring a large mask corresponding to the substrate and the substrate close to several tens of μm. Therefore, the mask and the substrate come into contact due to the flatness of the mask and the substrate, the surface shape (irregularity) of the resist applied to the substrate, and dust adhering to the surface, and the pattern of the mask is defect-free over the entire surface of the substrate. Transcription is quite difficult. Also,
The resolution of the image to be transferred, the line width,
Since the distance greatly affects the shape of the line, if the distance is not uniformly maintained at a design value, it is not suitable for manufacturing an active matrix type liquid crystal panel or a high definition STN type liquid crystal panel.

In the step-and-repeat method, a reticle of about 6 inches, which is relatively smaller than the substrate, is used as a mask, and transfer to a large substrate is performed by step-and-repeat. In this step-and-repeat method, a reticle used in the manufacture of a semiconductor device can be used as a mask, so that techniques cultivated in semiconductor device manufacture, such as drawing accuracy, pattern dimension management, dust management, etc., can be applied. it can. However, when transferring to a large substrate, in order to expose a device having an area that exceeds the effective projection area (image circle) of the projection optical system, the area to be transferred of the substrate is divided into small areas and each is exposed. It is necessary to perform so-called divided exposure. In the display section of an active matrix liquid crystal panel, when a small shift occurs at the boundary of a pattern formed by divided exposure, the performance of the element changes at this portion, and density unevenness occurs on the completed liquid crystal panel Will be. This is easily recognized as a difference by human eyes, and causes a defect in display quality of the liquid crystal panel. In addition, when the number of divisions increases, the number of exposures increases, and in addition, it is necessary to change the reticle many times while exposing one substrate, which causes a reduction in the processing performance of the apparatus.

Further, in the mirror projection system, the entire surface of the mask is transferred onto the substrate by relatively scanning an arc-shaped slit extending in a direction orthogonal to the scanning direction of the mask or the substrate with respect to the mask and the substrate. In order to expose a substrate efficiently, it is necessary to make the slit length as long as the size of the substrate. For this reason, it is necessary to increase the size of the optical system, and there is a problem in that the size of the apparatus must be increased to be expensive.

In view of the above problems, an object of the present invention is to provide an exposure apparatus that can efficiently perform exposure over a large area using a small projection optical system.

[0008]

According to the present invention, there are provided five illumination optical systems (L1 to L1) for irradiating a light beam from a light source (1) to a part (11a to 11e) of a pattern area of a mask (10). L5); being displaced from each other along a predetermined direction (Y direction) and in a direction (X direction) orthogonal to the predetermined direction, and each part of the light beam transmitted through the mask being a positive one-fold positive. Standing image (13a-13e)
Projection optical system (2) for projecting light onto a photosensitive substrate (14).
a to 12e); scanning means (16) for synchronously scanning the mask and the photosensitive substrate at the same speed in a direction substantially perpendicular to a predetermined direction with respect to the projection optical system, and ) Is a scanning type exposure apparatus for transferring the entire surface onto a photosensitive substrate. Each projection illuminated by five illumination optical systems
The area transfers the pattern area of the mask onto the photosensitive substrate
The edges of the projection areas adjacent to each other
It is configured to be arranged so as to overlap. Also book
In the present invention, an exposure method for exposing a pattern of a mask to a substrate
, Through a plurality of projection optical systems (13a to 13e)
The mask pattern is transferred to the substrate and multiple projections are performed.
A predetermined scanning method for the mask and substrate relative to the optical system
Exposure operation for synchronous scanning in the direction
And the step operation to step in the direction of
I do. In addition, the step operation is performed by a plurality of scans.
It is performed during the exposure operation. Also put on the mask putter
Multiple projection areas that can be transferred by multiple projection optics
Are arranged at regular intervals in the direction orthogonal to the inspection direction,
By performing the exposure operation and the step operation,
The exposed region is formed on the substrate. Also multiple
The projection area projected by the projection optical system of
The parts are arranged so as to overlap each other.

[0009]

According to the present invention, a projection optical system for forming an erect image at the same magnification is provided along a direction orthogonal to the scanning direction of the mask and the substrate.
Since the mask and the substrate are integrally scanned with respect to the five projection optical systems in a staggered arrangement, projections long in the direction orthogonal to the scanning direction can be performed without increasing the image circle of each projection optical system. Regions can be formed. For this reason, a conventional small projection optical system can be used. In addition, since the scanning direction is constant, an exposure apparatus smaller than the conventional one can be realized according to the size of the substrate by selecting the number of projection optical systems and the scanning distance. In addition, the scanning direction
Step in the crossing direction to make multiple scans
Exposure can be performed according to the size of the substrate.

[0010]

FIG. 1 is a diagram showing a schematic configuration of a projection exposure apparatus according to an embodiment of the present invention. A light beam emitted from a light source 1 such as an ultra-high pressure mercury lamp is reflected by an elliptical mirror 2 and then enters a dichroic mirror 3. The dichroic mirror 3 reflects a light beam having a wavelength required for exposure and transmits a light beam having another wavelength. The light beam reflected by the dichroic mirror 3 is selectively restricted from being irradiated on the projection optical system side by a shutter 4 arranged to be able to advance and retreat with respect to the optical axis AX1. When the shutter 4 is opened, the light beam enters the wavelength selection filter 5, and the wavelength (usually g, h, and g) suitable for the projection optical system 11a to perform transfer.
(at least one band of the i-line). Further, since the intensity distribution of the light flux is highest in the vicinity of the optical axis and becomes Gaussian distribution decreasing in the periphery, it is necessary to make the intensity uniform at least in the projection area 12a of the projection optical system 11a. For this reason, the intensity of the light beam is made uniform by the fly-eye lens 6 and the condenser lens 8. Incidentally, the mirror 7 is a bending mirror on the array.

The luminous flux having uniform intensity is applied to the pattern surface of the mask 10 through the field stop 9. The field stop 9 is used to project a projection area 13 on a photosensitive substrate (plate) 14.
It has an opening that restricts a. The field stop 9 and the mask 1
A lens system may be provided between 0 and 0 so that the pattern surface of the field stop 9 and the mask 10 and the projection surface of the plate 14 are conjugate to each other.

The configuration from the light source 1 to the field stop 9 is an illumination optical system L1 for the projection optical system 12a. In this embodiment, illumination optical systems L2 to L5 having the same configuration as described above are provided to project light beams from each of them. It supplies to each of the systems 12b-12e. Light beams emitted from each of the plurality of illumination optical systems L1 to L5 illuminate different small areas (illumination areas) 11a to 11e on the mask 10, respectively. The plurality of light beams transmitted through the mask are respectively transmitted to different projection optical systems 12a.
Through 12e different projection areas 13 on the plate 14
The pattern images of the illumination areas 11a to 11e of the mask 10 are formed on a to 13e. In this case, the projection optical systems 12a-1
Reference numeral 2e denotes an erecting unit-magnification real imaging system.

The projection area 13a on the plate 14
2 to 13e are adjacent to each other (for example, 13a and 13b, 13b and 13b) along the Y direction as shown in FIG.
c) are arranged so as to be displaced by a predetermined amount in the X direction in the figure, and so that the ends of the adjacent regions (ranges shown by broken lines) overlap in the Y direction. Therefore, the plurality of projection optical systems 1
2a to 12e are also displaced by a predetermined amount in the X direction according to the arrangement of the projection areas 13a to 13e, and are arranged so as to overlap in the Y direction. Further, the arrangement of the plurality of illumination optical systems L1 to L5 is such that the illumination area on the mask 10 is such that the projection areas 13a to 13a are arranged.
13e. And
The projection optical system 1 is synchronized with the mask 10 and the plate 14.
By scanning in the X direction with respect to 2a to 12e,
The entire surface of the pattern region 10a on the mask is transferred to the exposure region 14a on the plate.

The plate 14 is mounted on a plate stage 15, and the plate stage 15 has a driving device 16 having a long stroke in the scanning direction (X direction) to perform one-dimensional scanning exposure. Further, it has a high-resolution and high-accuracy position measuring device (for example, a laser interferometer) 17 in the scanning direction. The mask 10 is supported by a mask stage (not shown). The mask stage also has a driving device and a position measuring device for detecting the position of the stage in the scanning direction, like the plate stage 15.

Here, an example of a projection optical system applied to the exposure apparatus according to the present embodiment will be described with reference to FIGS. In the present invention, since a plurality of projection optical systems are arranged along the direction orthogonal to the scanning direction as described above, the images of the projection optical systems need to be erect images. In addition, we can improve the accuracy of the movement of the mask and plate,
It is conceivable to move the mask and the plate together for the purpose of preventing the apparatus from being enlarged due to the difference in the moving direction. Therefore, in the present invention, the mask and the plate are relatively scanned by the same amount in the same direction with respect to the projection optical system, and the projection optical system is an erecting unit-magnification real imaging system. In each of the drawings, the arrows shown by solid lines correspond to the pattern on the mask surface and the projected image on the plate.

FIG. 3 shows an example in which inverted real imaging systems 21 and 22 are arranged in series along the optical axis of the apparatus (so that the optical axes of the respective imaging systems coincide). In this case, the imaging system 21 and the imaging system 2
2 can be the same. It is also possible to use an equal magnification system as one of the imaging systems, and it is also possible to use a combination of an enlargement system and a reduction system. By arranging the imaging system symmetrically with respect to the intermediate image formed at the position of the arrow indicated by the dotted line in the drawing, the pattern of the mask can be formed on the plate as an erecting equal-magnification projection image.

FIG. 4 shows an example in which an image rotator is incorporated in an inverted real imaging system. In FIG. 4, if there is no image rotator 24, the image forming system constituted by the lens systems 23 and 25 is an inverted real image forming system. The image rotator 24 is a trapezoidal prism that has been roof-shaped.
FIG. 5 is an example using a distributed index glass. It is known that when a so-called distributed refractive index glass having a high refractive index at the center portion and decreasing toward the periphery and having a certain desired length is used, an actual-magnification real imaging system is obtained as shown in FIG. At this time, the end surface of the distributed refractive index glass 26 may be a flat surface or a curved surface (spherical or aspherical shape having a predetermined curvature).

In any of the examples, it is desirable that the projection optical system be telecentric on both the object point side and the image point side in order to avoid a change in the magnification of the image when the surface of the mask or plate changes in the optical axis direction. Next, the exposure operation will be described. An active matrix type liquid crystal panel requires a plurality of pattern layers to be overlapped and exposed in a manufacturing process in order to form the active element. For this reason, a plurality of masks 10 serving as original plates are required. First,
The mask 10 is positioned with respect to the exposure apparatus by a mask alignment system (not shown) held by a holding member holding the projection optical system. Similarly, plate 14
Is also positioned with respect to the exposure apparatus. Thus, mask 1
The exposure is performed by scanning the projection optical system in the X direction in the drawing at the same speed while synchronizing the mask and the plate while maintaining the state where the 0 and the plate 14 are positioned. At this time, in order to make the same exposure condition (uniform exposure amount) within the exposure area 14a indicated by the distances Lx and Ly, the scanning of the exposure between Lx must be performed at a constant speed in the scanning range in the X direction. . For this reason, scanning in the X direction requires a run so that the scanning speed becomes constant until Lx reaches the image forming range of the projection optical system. Scanning speed during exposure is v (cm / s), illumination power is P
(W / cm ² ) and the width of the opening is w (cm), the exposure amount D (J / cm ² ) obtained is

[0019]

(Equation 1)

Is given by Therefore, plate 1
The respective parameters can be determined in accordance with the exposure amount required for the photosensitive agent applied to No. 4. In the embodiment shown in FIGS. 1 and 2, the entire pattern is transferred by one scanning. However, it is also possible to perform the transfer over the entire exposure area on the plate by performing a plurality of scans. FIG. 6 shows, for example, 12 of the projection optical systems shown in FIG.
This is the case where only a, 12c and 12e are used. This is because three projection optical systems are arranged at a predetermined interval in a direction orthogonal to the scanning direction, and the projection area 13
a, 13c and 13e are formed. And the projection area 13
This is an example in which scanning in the X direction and steps in the Y direction are performed such that the scanning trajectory on the plate at the center of c becomes a broken line 61. Further, as shown in FIG. 7, for example, using only the projection optical systems 12a and 12b of FIG.
13b may be formed, and scanning and steps may be performed so that the center of the projection area 13a follows the locus of the broken line 62.

In the above embodiment, the shape of the area (projection area) in which the projection optical system can transfer images at a time is an elongated hexagon (13a to 13e) as shown in FIG. 2, but as another example, FIGS. The shape shown in FIG. 11 may be used. FIG.
Shows a case where the projection area is a regular hexagon, FIG. 10 shows a case of an equilateral trapezoid, and FIG. 11 shows a case of a parallelogram. 8 to 10 are image circles of the projection optical system. Needless to say, the projection area of the projection optical system is set by the opening of the field stop 9 in this circle. In any of the examples, the spreading direction of the width w coincides with the scanning direction (X direction in FIG. 2).
Further, when this projection area is considered as divided into a portion s projected only by one projection optical system during one scan of the plate and a portion t projected by a plurality of scans or a plurality of projection optical systems, The shape must satisfy the requirement that the sum of the exposure amounts for the plate in the portion t coincides with the exposure amount in the portion s.

[0022]

As described above, according to the present invention, the projection optical systems of the five erecting equal-magnification real imaging systems are staggered along the direction orthogonal to the scanning direction of the substrate, and the mask and the substrate are connected. Since the scanning is performed synchronously in the same direction, a larger projection area than before can be obtained while using a small projection optical system. Therefore, a compact and low-cost exposure apparatus can be realized. Also, exposure on the substrate by multiple scans
It becomes feasible to transfer the pattern over the entire area,
It is possible to efficiently expose patterns on large substrates.
You.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a state of a projection area on a plate.

FIG. 3 is a diagram showing an example of a projection optical system applied to a scanning exposure apparatus according to an embodiment of the present invention.

FIG. 4 is a diagram showing an example of a projection optical system applied to a scanning exposure apparatus according to an embodiment of the present invention.

FIG. 5 is a diagram showing an example of a projection optical system applied to a scanning exposure apparatus according to an embodiment of the present invention.

FIG. 6 is a diagram showing another example of the exposure operation.

FIG. 7 is a diagram showing another example of the exposure operation.

FIG. 8 is a diagram showing another example of the shape of the projection area.

FIG. 9 is a diagram showing another example of the shape of the projection area.

FIG. 10 is a diagram showing another example of the shape of the projection area.

[Description of Signs] L1 to L5 Illumination optical system 10 Mask 11a to 11e Illumination area 12a to 12e Projection optical system 13a to 13e Projection area 14 Plate 15 Stage 16 Driving device

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Muneyasu Yokota 3-2-2 Marunouchi, Chiyoda-ku, Tokyo Nikon Corporation (56) References JP-A-60-109228 (JP, A) JP-A-63 JP-A-49218 (JP, A) JP-A-4-196513 (JP, A) JP-A-1-101628 (JP, A) JP-A-61-176118 (JP, A) JP-A-7-86139 (JP, A) JP-A-52-15266 (JP, A) JP-A-4-251812 (JP, A) JP-A-7-57986 (JP, A) US Pat. No. 4,696,889 (US, A) US Pat. (58) Field surveyed (Int.Cl. ⁷ , DB name) G03F 7/20 H01L 21/027

Claims (6)

(57) [Claims] 1. Five illumination optical systems for irradiating a part of a pattern region of a mask with a light beam from a light source, and are arranged so as to be displaced from each other along a predetermined direction and in a direction orthogonal to the predetermined direction. And five projection optical systems for projecting an equal-length erect image of each of the portions by the light flux transmitted through the mask onto a photosensitive substrate, and in a direction substantially orthogonal to the predetermined direction with respect to the projection optical system. A scanning unit that scans the mask and the photosensitive substrate at the same speed in synchronization with each other, and transfers the entire surface of the pattern area onto the photosensitive substrate. 2. The projection system according to claim 1, wherein each of the projections is illuminated by the five illumination optical systems.
The shadow area is a pattern area of the mask on the photosensitive substrate.
The edges of the projection areas adjacent to each other as
Contractors characterized in that they are arranged so that they overlap
The scanning exposure apparatus according to claim 1. 3. Exposure for exposing a pattern of a mask to a substrate.
In the method, The mask pattern through a plurality of projection optical systems;
While transferring to the substrate, the plurality of projection optical systems
Relatively align the mask and the substrate in a predetermined scanning direction.
Exposure operation to perform initial scanning, Stepping the substrate in a direction perpendicular to the scanning direction.
An exposure method comprising: 4. The method according to claim 1, wherein the step operation is performed by a plurality of scans.
4. The method according to claim 3, wherein the exposure is performed during the exposure operation.
Exposure method described above. 5. The method according to claim 1, wherein the pattern of the mask includes the plurality of projections.
The plurality of projection areas transferred by the optical system correspond to the scanning direction.
Are arranged at regular intervals in the direction orthogonal to each other,
By performing the operation and the step operation,
An exposure area is formed on the substrate.
Item 5. The exposure method according to Item 3 or 4. 6. A projection projected by the plurality of projection optical systems.
Areas are arranged so that the ends of adjacent areas overlap
6. The exposure according to claim 3, wherein the exposure is performed.
Method.