JPH0367238A - Scanning type exposing device - Google Patents

Abstract

PURPOSE:To prevent the degradation in the accuracy of the patterns formed on an exposing object by moving the exposing object in accordance with the movement of the scale image actually projected via a projecting lens system. CONSTITUTION:A scale 22b to form the scale image moved together with the pattern image of an original picture is provided and the movement of the actual pattern image is detected by detecting the state of this scale image by a photodetecting means 48. The movement of the exposing object is controlled in accordance with this detection. Since the exposing object is thereby moved in follow up to the movement of the projected scale image, the errors, etc., of the projecting lens system 30 are canceled. The degradation in the accuracy of the patterns is prevented in this way even if there are the error in the magnification of the projecting lens system or the error in the moving quantity of the original picture and the exposing object.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention forms an image of a part of an original image on an exposure target, and then slides the exposure target and the original image relative to each other, thereby exposing the entire exposure target. The present invention relates to a scanning type exposure apparatus that performs.

[Prior Art] As described above, a scanning exposure apparatus that performs exposure by moving an original image and an exposure target relative to a projection lens,
There are copiers and exposure devices for fine patterns called steppers.

A copy machine continuously projects and exposes an image of an original onto a rotating photosensitive drum. In addition, the stepper
While the mask and the exposure target are moved intermittently, the image of the mask is divided into parts and projected onto the exposure target for exposure.

Incidentally, in the above-described scanning type exposure apparatus, it is necessary to correlate the amount of movement of the projection portion on the document with the amount of movement of the exposed portion on the exposure target, taking into consideration the magnification of the projection lens system.

Devices that do not require high precision, such as copy machines, use mechanical links to correlate the amount of movement. Also,
A device such as a stepper that requires high precision measures the amount of movement of the mask and the exposure target electrically by, for example, the number of pulses output according to the amount of movement. 1jllL, these associations are being made.

[Problem to be Solved by the Invention] However, in the above-described conventional scanning exposure apparatus, even though the original image and the exposure target are moved 111g4, the amount of movement is controlled using predetermined and fixed coefficients. Since the execution is based on the
I can't give feedback.

Therefore, if there is an error in the magnification of the projection lens, or if there is an error in the association of movement between the original image and the exposure target, there is a problem that the precision of the pattern formed on the exposure target is reduced.

[Object of the Invention] In view of the above-mentioned problems, the present invention provides a scanning method that can prevent a decrease in pattern accuracy even when there is a magnification error in the projection lens system or an error in the amount of movement of the original image or exposure target. The purpose is to provide a mold exposure device.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a scale that forms a scale image that moves together with the pattern image of the original image, and this scale f! By detecting the state of I with a light receiving means, the movement of the actual pattern II is detected,
It is characterized in that the movement of the exposure target is controlled based on this.

[Operation] According to the above configuration, since the exposure target is moved following the movement of the projected scale image, errors and the like of the projection lens system are canceled.

[Example] The present invention will be explained below based on the drawings.

(First Embodiment) FIGS. 1 to 5 show a first embodiment of a scanning exposure apparatus according to the present invention.

This device consists of a mercury lamp 1 as a light source, as shown in FIG.
1, and an exposure pattern is drawn'! :
A mask unit 20 having a liquid crystal light valve 21 as a RW mask, a projection lens system 30 that projects an f-elephant of the original image using the light beam transmitted through the liquid crystal light valve 21, and a workpiece 41 such as a printed circuit board to be exposed. The workpiece section 40 is generally composed of a workpiece section 40 and a workpiece section 40.

The light source unit IO averages the light emitted from the mercury lamp 11 using an integrator 12, and also uses a condenser lens 13 to average the light emitted from the mercury lamp 11.
The light is focused onto the liquid crystal light valve 21.

The liquid crystal light valve 21 has an exposure pattern formed by a writing optical system (not shown), and is placed on a mask table 22 . This mask table 22 has guide rails 23a of a mask space 23 which is a stationary system.
, 23a so as to be freely slidable.

Furthermore, an opening 23b is provided in the center of the mask space 23 to allow the light beam that has passed through the liquid crystal light valve 21 to pass through to the workpiece 40 side.

A feed screw 25 is installed parallel to the guide rail 23a between bearings 24, 24 provided at both ends of the mask space 23, and this feed screw 25 is installed on the mask table 22.
A feed nut 22a is provided which is screwed into the feed nut 22a. The feed screw 25 is rotationally driven by a servo motor 26, thereby causing the mask table 22 to slide along the guide rail 23a. These feed screw 25, feed nut 22a, and servo motor 26 constitute a first drive mechanism that relatively moves the original image and the projection lens system.

Note that a speed detector 26a is attached to the servo motor 26 to detect the rotation speed of its rotating shaft.

A striped projection scale 22b whose transmittance changes along the sliding direction of the mask table 22 is provided in a part of the mask table 22 adjacent to the liquid crystal light valve 21. The light flux transmitted through this projection scale 22b is
A striped pattern image is formed on the workpiece 40 via the projection lens system 30.

Further, a first linear scale 22c having a cotton-like pattern whose transmittance changes along the sliding direction of the table is attached to the side of the mask table 22, and the first linear scale 22c is attached to the mask space 23.
A first linear head 27 is provided between the two. 1st
The linear head 27 has a light emitting part and a light receiving part facing each other with the linear scale 22c in between, and outputs a pulse corresponding to the amount of movement as the first linear scale moves.

The projection lens system 30 uses a telecentric lens system for fi (II) so that an accurate pattern can be formed even when the flatness of the exposure target is low or the projection lens system is defocused. However, a telecentric lens consisting of a rotationally symmetrical lens is
Since the diameter of the lens on the exposure target side is large enough to include at least the entire exposure target, there is a problem in that as the exposure target becomes larger, it becomes difficult to manufacture the lens in terms of cost.

Therefore, the projection lens system 30 of this embodiment is composed of a rotationally symmetrical first lens group 31 and a second lens group 32 having a shape in which a portion of a circular lens including the diameter is cut out into a planar rectangle. The light beam from the light source unit 10 that has passed through the liquid crystal light valve 21 and the opening 23b is imaged onto the workpiece 41 in the form of a slit.

The work unit 40 includes a work table 42 on which a work 41 is placed, and a work base 43 that is a stationary system. The work table 42 is slidably engaged with guide rails 43a, 43a provided on the work base 43.

A feed screw 45 is installed parallel to the guide rail 43a between bearings 44, 44 provided at both ends of the work base 43, and the feed screw 45 is installed on the work table 42.
A feed nut 42a is provided which is screwed into the feed nut 42a. The feed screw 45 is rotationally driven by a servo motor 46, thereby causing the work table 42 to slide along the guide rail 43a. These feed screw 45, feed nut 42a, and servo motor 46 constitute a second drive mechanism that relatively moves the exposure target and the projection lens system.

Note that a speed detector 46a is attached to the servo motor 46 to detect the rotation speed of its rotating shaft.

Furthermore, a second linear scale 42b having a cotton-like pattern whose transmittance changes along the sliding direction of the table is attached to the side of the work table 42, and the second linear scale 42b is attached to the work base 43.
A second linear head 47 is provided on both sides. Second
The linear head 47 has a light emitting section and a light receiving section that face each other with the linear scale 42b in between, and outputs a pulse corresponding to the amount of movement of the second linear scale.

Further, below the second lens group 32, a third linear head 48 as a light receiver is provided adjacent to the second linear head 47. An image of the projection scale 22b that moves as the mask table moves is formed on the third linear head 48, and pulses corresponding to the amount of movement of the mask table 22 are output.

FIG. 2 shows the control system of the device described above.

This device includes a system that controls the movement of the mask table 22, centered around a central controller 100 that controls the entire system;
A system for controlling the movement of the work table 42 based on the amount of movement of the mask table 22 is provided independently.

The mask side system includes a pulse distributor 110 that determines the amount of movement.
a deviation counter 111 that detects and corrects the deviation between the determined pulse and the actual movement pulse detected from the first linear head 27; and a D/A converter 112 that converts the output of the deviation counter 111 into analog. A servo amplifier 113 that supplies drive current to the servo motor 26 while receiving feedback based on the output of the speed detector 26a.
It is equipped with

On the other hand, the work side system is a pulse distributor serving as a link means that detects the movement amount of the mask table 22 including the magnification error of the optical system based on the output of the third linear head 48 and determines the movement amount of the work table 42. 120, a deviation counter 121 that detects a deviation based on the output C of the second linear head 47, a D/A converter 122, and a servo amplifier 123 that supplies a drive current to the servo motor 46 based on the output of the speed detector 46a. It is equipped with

Due to the groove bottom, the mask table 22 is connected to the central controller 1.
It is moved at a predetermined speed according to commands from 00.

On the other hand, the work table 42 is twice as large as the projection lens system 30 output from the third linear head 48! ! The mask table is moved based on the amount of movement of the mask table including the error.

FIG. 3 shows an example in which the projection scale is shared for detecting the amount of movement on the mask table side and detecting the amount of movement on the work table side.

That is, the light beam from the light source unit 10 is divided by the half mirror 50, the reflected component is reflected by the mirror 51, and is received by the first sonia head 27 via the projection scale 22b, and the transmitted component is transmitted to the projection scale 22b and the projection lens system. 30
The light is received by the third linear head 48 via.

The first linear head 27 detects the amount of movement of the mask table 22, and the third linear head 48 detects the amount of movement of the mask table 22 including the magnification error of the projection lens.

Control after detection is the same as in the above embodiment.

In the above embodiment, both tables are controlled in a closed loop, but the mask table 22 side can also be controlled in an oven loop in principle. However, in devices that draw fine patterns on photosensitive materials such as resists, minute changes in the exposure amount can greatly affect the line width.
As mentioned above, the mask table side also needs to be controlled in a closed loop.

Further, the third linear head 48 may be a light-receiving element such as a single photodiode, but it may also have a configuration as shown in FIG. 4.

That is, the third linear head 48 shown in this example has four light receiving elements 48a, 48b, and 48c whose phases are different by 1/4 pitch with respect to the pitch of the projected scale image.
.

48d, and a scanning plate 48e in which openings corresponding to these light receiving elements are formed. Each light receiving element 4
The phase differences of 8a to 48d are 0°, 90', 180°, and 270@ with respect to the pitch of the scale image.

Signal detection using such a linear head will be explained based on FIG. 5.

The outputs of the light receiving elements 48a and 48c and the light receiving elements 48b and 48d are connected in a bushing manner to generate two push-pull signals 11. whose phases are shifted by 90 degrees from each other. Obtain I2. II, I
Since 2 is an analog output, it is digitized by a waveform shaping circuit as a rectangular wave signal [1,02.

Next, by detecting the edges of the rectangular wave signals 111 and 112 and generating pulses, push-pull signals ■1,
A pulse signal Up having a frequency four times that of I2 is generated, and the work table is driven in synchronization with this signal.

In principle, detection is possible with one light-receiving element as described above, but by using four light-receiving elements arranged at positions with a phase difference of 90 degrees relative to the pitch of the scale image, The direction of movement can be detected, and the accuracy of detecting the amount of movement can be improved by generating pulses with four times the frequency.

In addition, by pairing the outputs of the light receiving elements with phases different by 180° and connecting them in a push-pull manner, even if the pitch of the scale image changes due to a magnification error in the optical system, the SN
Although the ratio decreases, the pulse period can be detected without changing.

(Second Embodiment) FIGS. 6 and 7 show a second embodiment of the present invention.

If the precision of the pattern to be drawn is relatively loose, or
When using a photosensitive material with a steep rise in exposure, such as lithographic film, as the photosensitive material to be exposed, it is not necessary to strictly control the moving speed of the mask table as in the first embodiment. The second embodiment shows an apparatus in which the movement of the mask table is performed in an open loop to simplify control in such a case.

This apparatus does not include a linear scale for detecting the amount of movement of the mask table and a speed detector for detecting the rotational speed of the motor, and instead uses a stepping motor 27 as the first driving means.

The other configurations are the same as in the first embodiment.

The circuit configuration is as shown in FIG. 7, and the stepping motor 27 is directly driven based on pulses output from the pulse distributor 110 based on commands from the central controller 100. Control on the work table side is the same as in the first embodiment.

In the above two embodiments, only a device that forms an image using a light beam transmitted through an original image and a scale is described, but the present invention is applicable to a device that forms an image using a reflected light beam, such as a copy machine, for example. It is also possible to apply

Further, as the object to be exposed, not only the flat photosensitive material as described above but also a drum-shaped photoreceptor may be exposed.

[Effect] As explained above, according to the present invention, since the exposure target is moved based on the movement of the scale image actually projected through the projection lens system, there is a magnification error in the projection lens system. Even if the movement of the original image becomes unstable, the exposure target can be moved in a manner that includes these errors.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an optical system showing a first embodiment of a scanning exposure apparatus according to the present invention, FIG. 2 is a block diagram showing a control system of the apparatus shown in FIG. 1, and FIG. FIG. 4 is an explanatory diagram showing details of the linear head; FIG. 5 is a graph showing signal processing from the linear head shown in FIG. 4. . FIG. 6 is an explanatory diagram of an optical system showing a second embodiment of the present invention;
FIG. 7 is a block diagram showing the control system of the apparatus shown in FIG. 6. 21... Liquid crystal light valve (original fli) 30... Projection lens system 41... Workpiece (exposure target) 48... Third linear head (light receiving means) 22b...
Projection scale 120...Pulse distributor (link means) Fig. 1 Fig. 3 Fig. 5 Fig. 5

Claims (1)

[Scope of Claims] A projection lens system that images a part of an original image on which an exposure pattern is drawn onto an exposure target; and a first drive mechanism that relatively moves the original image and the projection lens system. , a second driving means for relatively moving the exposure target and the projection lens system; a projection scale that is moved together with the original image and forms a scale image on the exposure target side via the projection lens system; a light-receiving means for detecting movement of the scale image; and a light-receiving means for detecting the movement state of the image of the original image based on the output of the light-receiving means, so that the exposure target is moved in synchronization with the movement of the image. 1. A scanning exposure apparatus comprising: a link means for controlling a drive means.