JP2000049078A - Exposing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable one photosensitive substrate to be exposed under more conditions by setting the energy of exposed light at every one of a plurality of optical paths so that the exposure to the first one of a plurality of transfer areas may become different from that to the second transfer area. SOLUTION: Exposed light rays from a plurality of illuminating optical systems I1-I5 irradiate different areas to be irradiated on a mask M and projection optical systems L1-L5 respectively form the images corresponding to the illuminated areas in different transfer areas PA1-PA on a glass plate P which is a photosensitive substrate. The energy of parallel exposed light rays is set so that the exposure to the first transfer area PA1 may become different from that to the second transfer area PA2. Therefore, the exposing conditions of one glass plate P can be set easily in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure method for selecting a desired exposure condition using an exposure apparatus for manufacturing a semiconductor element, a liquid crystal display element, and the like. The present invention relates to an exposure method suitable for setting an energy amount.

[0002]

2. Description of the Related Art In recent years, liquid crystal display substrates which can be made thinner have been frequently used as display elements for personal computers and televisions. This type of liquid crystal display substrate is manufactured by patterning a transparent thin-film electrode into a desired shape on a rectangular glass plate in a plan view by a photolithography technique. As a photolithography apparatus, a projection exposure apparatus that exposes an exposure pattern formed on a mask to a photoresist layer on a glass plate via a projection optical system is used.

Conventionally, in this type of exposure apparatus, a pattern (a geometrical pattern formed by a light transmitting portion and a light shielding portion) formed on a mask is formed on a glass plate coated with a resist layer having a fixed thickness (about 1 to 5 μm). Pattern) to expose the image
An illumination optical system that irradiates exposure light having a substantially constant light intensity with a uniform illuminance distribution from above the mask for a predetermined time, or exposure light (pulse light) from a pulsed laser light source
An illumination optical system for irradiating a plurality of pulses until a predetermined light intensity integration is obtained is provided. In any case, the above-mentioned exposure apparatus converts the pattern image of the mask into an optimal exposure amount for the resist layer, that is, an optimal energy amount in order to control the line width of the pattern formed on the resist layer with sufficient accuracy. It is controlled so as to print.

Therefore, in the exposure apparatus, a test exposure is performed on the glass plate in order to find an optimum amount of exposure light to the glass plate, and then the glass plate is developed, and the line width of the linear pattern is determined by an optical microscope. Or by using a dedicated line width measurement device and comparing it with the designed line width value, or by using the fact that the line width becomes the smallest under certain conditions, determine the optimal exposure conditions Has been done.

For example, in a scanning type exposure apparatus in which a mask and a glass plate are synchronously moved in a predetermined scanning direction with respect to one projection optical system, the irradiation time is changed by changing the scanning speed in the scanning direction during test exposure. Are variously changed. Thereby, as shown in FIG. 6, the glass plate 1 in which the areas A1 to A4 having different energy amounts of the exposure light are arranged in the scanning direction is obtained.

After the development, each formed area A1 is formed.
It is conceivable that the line width of the linear resist pattern in A4 is directly measured, and the line width becomes a design value, or the scanning speed of an area closest to the design value is set as the optimal exposure condition. ing.

[0007]

However, the conventional exposure method as described above has the following problems. In a scanning type exposure apparatus having only one projection optical system, the energy amount of exposure light can be changed only in the scanning direction. Therefore, in order to perform test exposure under more conditions in order to select the optimal energy amount of exposure light, a large number of test glass plates are required,
There is a problem that it takes much effort and time.

The present invention has been made in consideration of the above points. In order to select an optimum amount of energy of exposure light, even when a test exposure is performed on a photosensitive substrate, a single photosensitive substrate can be used. An object of the present invention is to provide an exposure method capable of performing exposure under more conditions.

[0009]

In order to achieve the above object, the present invention employs the following structure corresponding to FIGS. 1 to 5 showing an embodiment. According to the exposure method of the present invention, the mask (M) and the photosensitive substrate (P) are synchronously moved with respect to a plurality of parallel optical paths, and an image of the mask (M) is exposed by the exposure light from each of the plurality of optical paths. P) In the exposure method for scanning and exposing a plurality of transfer areas (PA1 to PA5), the first of the plurality of transfer areas (PA1 to PA5) is exposed.
Energy of the exposure light for each of the plurality of optical paths so that the amount of exposure to the transfer area (PA1) differs from the amount of exposure to the second transfer area (PA2) different from the first transfer area (PA1). The amount is set.

Therefore, in the exposure method of the present invention, when the mask (M) and the photosensitive substrate (P) move synchronously with respect to a plurality of optical paths, the image of the mask (M) is moved to the plurality of photosensitive substrates (P). The first transfer area (PA1) and the second transfer area (PA2) among the transfer areas (PA1 to PA5) are scanned and exposed with exposure light having different energy amounts. Therefore, by measuring the image of the mask (M) exposed to the first and second transfer areas (PA1, PA2), it is possible to select the optimal exposure amount at the time of exposure.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an exposure method according to the present invention will be described below with reference to FIGS. In these figures, the same components as those in FIG. 6 shown as a conventional example are denoted by the same reference numerals, and description thereof will be omitted. FIG. 2 is a schematic configuration diagram of the exposure apparatus 2.

The exposure apparatus 2 scans and exposes an image of the mask M on a glass plate (photosensitive substrate) P by synchronously moving a mask M and a rectangular glass plate P with respect to a plurality of parallel optical paths. A plurality of illumination optical systems I1 to I5;
A plurality of projection optical systems L1 to L5, a mask stage 3,
And a plate stage 4. In addition, each of the plurality of optical paths includes each of the illumination optical systems I1 to I5 and each of the projection optical systems L1 to L5.

The illumination optical systems I1 to I5 illuminate the exposure area of the mask M with the exposure light of each optical path. As shown in FIG. The diaphragm (not shown) and the lens system 7 are mainly constituted. In the present embodiment, the illumination optical systems I2 to I5 having the same configuration as the illumination optical system I1 are arranged at regular intervals in the X direction and the Y direction. (However, in FIG. 1, only the one corresponding to the illumination optical system I1 is shown for convenience.) Then, the exposure light from each of the illumination optical systems I1 to I5 illuminates a different illumination area on the mask M. ing.

The light source 5 irradiates exposure light with electric power supplied from a power supply 8. The elliptical mirror 6 focuses the exposure light emitted by the light source 5. The field stop adjusts the illumination range of the exposure light collected by the elliptical mirror 6 through an opening. The lens system 7 forms an image of the aperture of the field stop on the illumination area of the mask M.

The projection optical systems L1 to L5 form images corresponding to the illumination area of the mask M on different transfer areas PA1 to PA5 on the glass plate P as shown in FIG. Both are equated erect. The transfer areas PA1 to PA5 are adjacent areas (for example,
PA1 and PA2, and PA2 and PA3) are arranged so as to be displaced by a predetermined amount in the X direction, and so that ends of adjacent regions overlap in the Y direction.

Accordingly, the projection optical systems L1 to L5 are displaced by a predetermined amount in the X direction according to the arrangement of the transfer areas PA1 to PA5, and are arranged so as to overlap in the Y direction.
In the illumination optical systems I1 to I5, the illumination areas on the mask M are arranged in the same manner as the above-described transfer areas PA1 to PA5.

The mask stage 3 holds the mask M, and includes a mask stage driving unit 9 having a long stroke in the scanning direction (X direction) to perform one-dimensional scanning exposure. The plate stage 4 holds the glass plate P and, like the mask stage 3, includes a plate stage drive unit 10 having a long stroke in the X direction for performing one-dimensional scanning exposure.

The mask stage driving unit 9
The plate stage drive unit 10 is connected to the stage control unit 11. The stage control unit 11 includes both drive units 1
By controlling 0 and 11, the mask M and the glass plate P are synchronously moved in the X direction at an arbitrary scanning speed (synchronous moving speed) with respect to the projection optical systems L1 to L5.

On the other hand, the exposure apparatus 2 has an illuminance setting mechanism 1
2 is attached. The illuminance setting mechanism 12 sets the illuminance of the exposure light for each optical path, thereby setting the transfer areas PA1 to PA1.
This is for setting the amount of exposure to the PA5, and includes a half mirror 13, a detector 14, a filter 15, a filter driving unit 16, and a signal processing unit 17.

The half mirror 13 includes illumination optical systems I1 to I
5 is arranged in the optical path between the light source 5 and the lens system 7, and makes a part of the exposure light incident on the detector 14.
The detector 14 detects the illuminance of the incident exposure light, and outputs a detected illuminance signal to the signal processing unit 17. These half mirror 13 and detector 14 are
It is provided for each of a plurality of optical paths.

The filter 15 is formed such that the transmittance gradually changes linearly in a certain range along the Y direction, and is disposed between the light source 5 and the half mirror 13 in each optical path. The filter driving unit 16 includes a signal processing unit 17
The filter 15 is moved along the Y direction based on the instruction.

The signal processing section 17 calculates a difference between the illuminance signal output from the detector 14 and a predetermined target illuminance, and controls the filter driving section 16 so as to correct the difference. The signal processing unit 17 includes a main control unit 18
Is connected. The main control unit 18 is configured to instruct the signal processing unit 17 of a target illuminance for each optical path and to control the stage control unit 11.

The operation of the exposure apparatus having the above configuration will be described.
First, the exposure light emitted from the light source 5 through the elliptical mirror 6 passes through the filter 15, and a part of the exposure light enters the detector 14 by the half mirror 13. The detector 14 detects the illuminance of the incident exposure light, and outputs a detected illuminance signal to the signal processing unit 17. The signal processing unit 17
The difference between the illuminance signal of the exposure light detected for each optical path and the target illuminance of each optical path is calculated, and the filter driving unit 16 is controlled so as to correct the difference. As a result, the filter 15 moves in the Y direction, and the transmittance for exposure light changes. Therefore, the exposure light in each optical path is set to the target illuminance after passing through the set filter 15.

On the other hand, the exposure light from the light source 5 passes through the half mirror 13 and forms an image corresponding to the aperture of the field stop on the illumination area of the mask M by the lens system 7. Mask M
The image corresponding to the illumination area of the mask M and the glass plate P
Move synchronously with respect to the projection optical systems L1 to L5, so that the glass plate P
The image is projected and transferred onto the upper predetermined transfer area at the same magnification erect.

Next, a method for performing test exposure on the glass plate P using the exposure apparatus 2 having the above-described configuration will be described. First, the main control unit 18 sets a target illuminance for each optical path, for example, 90 mW and 95 mW for the transfer areas PA1 to PA5, respectively.
100 mW, 105 mW, and 110 mW are set. Here, in the case where a circuit pattern or the like actually formed on the mask M is synthesized and transferred onto the glass plate P by the plurality of projection optical systems L1 to L5 instead of the test exposure, all illuminances need to be uniform. Therefore, the target illuminance of each of the illumination optical systems I1 to I5 is set lower than the maximum transmittance of each filter 15.

Further, the main controller 18 sets the scanning speed of the mask stage 3 and the plate stage 4 to 120 mm / sec in one scanning exposure as shown in FIG.
110mm / sec, 100mm / sec, 90mm /
An input is performed so that the exposure area at each scanning speed becomes substantially the same so as to change stepwise in seconds.

When scanning exposure is performed using a mask M on which a test pattern (for example, a line and space pattern formed at a predetermined interval) is formed under the above conditions,
As shown in FIG. 4, on the glass plate P, a plurality of (five) transfer areas PA1 to PA2 having different illuminances, that is, different exposure amounts are formed in the Y direction. In addition, on the glass plate P, a plurality of (four) transfer regions having different scanning speeds, that is, different exposure times per unit length are formed in the X direction.

As a result, on the glass plate P, a plurality of (20) transfer areas are formed in a matrix form, each area being exposed under the exposure condition in which the energy amount of the exposure light is different. Then, after development, the line width of the pattern transferred for each transfer area is measured by a predetermined measuring device, and compared with the designed line width, or by selecting the minimum line width, the optimum scanning is performed. Speed and illumination can be determined.

In the exposure method according to the present embodiment, since the scanning speed is changed and the illuminance is set for each of the plurality of optical paths, a transfer area having various exposure amounts simultaneously with the exposure time can be formed. Can be. Therefore, in the exposure method according to the present embodiment, it is possible to expose one glass plate P under more conditions with different amounts of energy of exposure light in one scanning exposure. In addition, as a result, optimal conditions for exposure can be selected, which leads to improvement in quality of the exposed device.

In the above embodiment, a plurality of parallel optical paths are provided at five locations, and the illumination optical system and the projection optical system are provided correspondingly. It is not something to be done. Further, the light source is provided for each illumination optical system. However, the present invention is not limited to this. For example, as shown in FIG.
, Light from a plurality of light sources (or one) may be combined into one, and the light may be split again for each optical path.

In the above embodiment, the scanning speed and the illuminance of the optical path are changed during one scanning exposure. However, the exposure may be performed by changing only the illuminance. Furthermore, the exposure amount is used as a parameter to be set by changing the energy amount of the exposure light for each transfer area, and the exposure amount is changed by changing the illuminance. However, the present invention is not limited to this. May be used to change the exposure amount.

The exposure apparatus has a configuration in which the mask and the glass plate move in the X direction. However, the exposure apparatus is a step-and-scan type exposure apparatus in which a driving device movable on the plate stage in the Y direction is provided. You may. Further, as long as it has a plurality of optical paths, the present invention can be applied to a mirror projection type exposure apparatus that does not use a projection optical system. Further, the present invention can be applied to a vertical exposure apparatus that supports the mask M and the glass plate P along the vertical direction.

The type of the exposure apparatus is not limited to an exposure apparatus for manufacturing a liquid crystal display element, but can be widely applied to, for example, an exposure apparatus for manufacturing a semiconductor and an exposure apparatus for manufacturing a thin film magnetic head.

As a light source of the illumination optical system, a bright line (g line, i line) generated from a mercury lamp, a KrF excimer laser (248 nm), and an ArF excimer laser (193n) are used.
m), not only the F ₂ laser (157 nm) only, it is possible to use a charged particle beam such as X-ray or electron beam. For example,
When an electron beam is used, thermionic emission type lanthanum hexaborite (LaB ₆ ), tantalum (T
a) can be used.

The magnification of the projection optical system may be not only the same magnification but also any of a reduction system and an enlargement system. Further, as the projection optical system, when using a far ultraviolet rays such as an excimer laser using a material which transmits far ultraviolet rays such as quartz and fluorite as glass material, catadioptric or refractive When using a F ₂ laser or X-ray The optical system may be a reflection type reticle. When an electron beam is used, an electron optical system including an electron lens and a deflector may be used as the optical system. It is needless to say that the optical path through which the electron beam passes is in a vacuum state.

When a linear motor is used for the plate stage or the mask stage, any of an air levitation type using an air bearing and a magnetic levitation type using Lorentz force or reactance force may be used. Further, the stage may be a type that moves along a guide, or may be a guideless type in which a guide is not provided.

The reaction force generated by the movement of the plate stage is mechanically moved to the floor (ground) using a frame member.
You may escape to The reaction force generated by the movement of the mask stage may be mechanically released to the floor (ground) using a frame member.

The illumination optical system and the projection optical system composed of a plurality of lenses are incorporated in the main body of the exposure apparatus for optical adjustment, and a reticle stage or a wafer stage composed of a number of mechanical parts is mounted on the main body of the exposure apparatus for wiring. And pipe connection, and further comprehensive adjustment (electrical adjustment, operation check, etc.)
By doing so, the exposure apparatus of the present embodiment can be manufactured. Here, it is desirable to manufacture the exposure apparatus in a clean room where the temperature and cleanliness are controlled.

In the liquid crystal display element, a step of designing the function and performance of the liquid crystal display element, a step of manufacturing a mask M based on the design step, a step of manufacturing a glass plate P from a glass material, It is manufactured through a step of exposing the pattern of the mask M to the glass plate P by an exposure device, a step of assembling a liquid crystal display element, and an inspection step.

[0040]

As described above, in the exposure method according to the first aspect, the energy amount of the exposure light is set for each of the plurality of optical paths so that the amount of exposure to a different one of the plurality of transfer regions is different. Configuration. Thereby, in this exposure method, it is possible to expose one photosensitive substrate under more conditions with different amounts of energy of the exposure light in one scanning exposure, and it is easy to select the exposure conditions, and An excellent effect that it can be performed in a short time is obtained. In addition, the optimum conditions for exposure can be selected, and the effect of improving the quality of the exposed device can be obtained.

According to a second aspect of the present invention, each of the plurality of optical paths includes a projection optical system for projecting the image of the mask onto the photosensitive substrate. Accordingly, this exposure method has an excellent effect that exposure can be performed under more conditions with different amounts of energy of exposure light, particularly in a multi-lens type exposure apparatus using a plurality of projection optical systems.

According to a third aspect of the present invention, the synchronous moving speed between the mask and the photosensitive substrate is changed during the scanning exposure. Thereby, this exposure method has an excellent effect that one photosensitive substrate can be exposed under more conditions in which the exposure time is variously changed in addition to the exposure amount.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of the present invention, and is a schematic configuration diagram of an exposure apparatus provided with an illuminance setting mechanism.

FIG. 2 is an external perspective view of the exposure apparatus.

FIG. 3 is a diagram illustrating the embodiment of the present invention, and is a relationship diagram illustrating a relationship between a position of a glass plate and a scanning speed.

FIG. 4 is a view showing an embodiment of the present invention, and is a plan view in which a transfer region is formed on a glass plate under a plurality of exposure conditions.

FIG. 5 is a diagram showing another embodiment of the illumination optical system constituting the present invention, and is a schematic configuration diagram in which light from a light source is combined and branched by a light guide.

FIG. 6 is a plan view of a glass plate on which a transfer area is formed by a conventional exposure method.

[Explanation of symbols]

 M mask P glass plate (photosensitive substrate) PA1 to PA5 transfer area L1 to L5 projection optical system

Claims (3)

[Claims] 1. A mask and a photosensitive substrate are synchronously moved with respect to a plurality of parallel light paths, and scanning exposure of an image of the mask is performed on a plurality of transfer areas of the photosensitive substrate by exposure light from each of the plurality of light paths. In the exposure method, the plurality of optical paths may be different such that an exposure amount to a first transfer region of the plurality of transfer regions is different from an exposure amount to a second transfer region different from the first transfer region. An exposure method, wherein an energy amount of the exposure light is set for each exposure. 2. The exposure method according to claim 1, wherein each of the plurality of optical paths includes a projection optical system that projects the image of the mask onto the photosensitive substrate. 3. The exposure condition selecting method according to claim 1, wherein a synchronous movement speed between the mask and the photosensitive substrate is changed during the scanning exposure.