JPH04229843A - Shutter for exposing device - Google Patents

Abstract

PURPOSE:To increase speed of shutter motion. CONSTITUTION:This shutter is featured that it consists of an interrupting part 3a for interrupting a beam and a rotator 3 with an opening part 3b for passing the beam through, while it continuously operates this rotator 3 without stopping it once during one time exposure operation till it returns to the closed state again after shifting from a shutter closed state to the opened state.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed shutter in a reduction exposure projection apparatus (hereinafter referred to as a stepper), and more particularly to a high-speed shutter having a function of controlling the cumulative exposure amount.

0002

[Prior Art] The shutter of a conventional stepper changes from the closed state to the open state, stops once, measures the cumulative exposure, and when this value reaches a specific exposure, changes the shutter from the open state to the closed state. .

FIG. 2 is an explanatory diagram of conventional shutter operation, where the horizontal axis shows time and the vertical axis shows the rotational position of the shutter. The shutter is, for example, a rotary shutter with three blades, and the rotational position where the blades block the light flux is the shutter closed position.

In FIG. 2, 30 indicates the width of the light beam passing through the shutter. 31 and 33 are the timings for the shutter closed state, and 32 are the timings for the shutter open state. Further, horizontal hatching in this figure indicates temporal positional changes of the shutter blades. That is, the horizontally hatched portion is a light blocking portion.

[0005] The area where the other part (the part without blades) intersects with the beam width 30 is the total amount of light flux passing through the shutter, and this is shown by diagonal hatching.

When a conventional shutter performs exposure, it starts measuring the cumulative exposure amount, starts driving the shutter from the shutter closed state 1, and stops the shutter when the shutter reaches the open state 32. Thereafter, the measurement of the cumulative exposure amount is continued, and when this value becomes the value obtained by subtracting the overexposure amount at the time of the shutter closing operation from the target cumulative exposure amount, the shutter closing operation is started.

In other words, the cumulative exposure amount is controlled by creating a completely open and still state of the shutter each time and controlling the time period in which this state remains.

[0008] For this reason, it is necessary to drive the shutter twice for one exposure operation, and there is a limit to increasing the speed.

[0009]

[Problems to be Solved by the Invention] Conventional shutters require two operations each: acceleration and deceleration when changing from a closed state to an open state, and acceleration and deceleration when changing from an open state to a closed state, resulting in high-speed operation. There was a limit.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide a shutter for an exposure apparatus that can operate at a higher speed than the prior art.

[0011]

[Means for Solving the Problems] In order to achieve the above-mentioned object, a high-speed shutter according to the present invention includes a rotating body having a blocking portion for blocking a light beam and an opening for passing the light beam, and the shutter changes from a closed state to an open state. The rotary body is operated continuously without once stopping until it shifts to the closed state and returns to the closed state again.

0012

[Operation] In a rotary shutter in a stepper, an exposure operation is performed without stopping rotation until the shutter changes from a closed state to an open state and then to a closed state.

Furthermore, in this operation, the optimum shutter speed is calculated from the cumulative exposure amount measured at the end of each exposure, and the shutter is driven at the next exposure using this shutter speed. Furthermore, after the shutter is driven, the laminated exposure amount is measured up to a specific time, and if this value is below a certain value, the shutter speed command value is decreased halfway, and if this value is above a certain value, the shutter speed command value is decreased halfway. Conversely, increase the shutter speed command value.

[0014]

[Embodiment] Fig. 1 is a system configuration diagram of the present invention, where 1 is a mercury lamp as a light source, 2 is an elliptical mirror for guiding the light from the mercury lamp 1 onto a reticle (not shown), and 3 is an elliptical mirror. This is a rotary shutter that controls the time during which the light from 2 illuminates the reticle, and is made up of three blades 3a that block the light flux and an opening 3b that allows the light flux to pass through. 4 is a lens, 5 is a half mirror that guides a portion of the light that has passed through the shutter to a photodetector 8 for measuring the cumulative exposure amount, 6 is a DC motor for driving the shutter, and 7 is a rotary encoder for detecting the rotation of the shutter. .

Further, 10 is a current driver that drives the shutter drive DC motor 6, and 11 is an FVC (Frequency Voltag) that exchanges a pulse train proportional to the shutter speed from the rotary encoder 7 into a voltage.
e Converter) 12 is a VFC (Voltage Freq) converter that converts an analog voltage proportional to the exposure amount from the integrated exposure measurement photodetector 8 into a pulse train.
Converter) 13 is shutter 3
a speed servo amplifier that generates an output proportional to the difference between the actual speed and the secondary speed command value 24 so that the actual speed of the secondary speed command value 24 matches the secondary speed command value 24;
is a multiplier for creating the secondary speed command value 24 from the primary speed command value 21 and the gain control data 20; 15 is a position counter that monitors the rotational position of the shutter by counting; 16 is the output from the VFC 12. An integrated exposure amount counter 17, which monitors the time-integrated amount of light incident on the photodetector 8 after the shutter opening operation by counting pulses, is a control for controlling the overall operation.

FIG. 3 is an explanatory diagram of the shutter operation of the present invention, where the horizontal axis represents time and the vertical axis represents the rotational position of the shutter. Reference numerals 34 and 35 each indicate the timing of the shutter closed state, and 36 indicates an example of the timing of measuring the cumulative exposure amount during the shutter drive. 30 indicates the width of the light beam passing through the shutter. As is clear from the comparison with FIG. 2, the shutter operation in FIG. 3 requires only one shutter drive for one exposure operation. Therefore, it is possible to achieve a cumulative exposure amount that is approximately 50% smaller than that of conventional shutter operation. However, in order to control the cumulative exposure amount so that it does not depend on the light intensity of the light source, it is necessary to control the rotation speed of the shutter.

[0017] Two specific methods can be considered.

One is to rotate the shutter at the optimal speed to achieve the target exposure amount during initial exposure, and after exposure, determine the optimal shutter drive speed to achieve the target exposure amount from this cumulative exposure data. The shutter is driven at this speed during the next exposure. However, it is impossible to correct short-term fluctuations in the light source using this method alone.

Another method is to measure the cumulative exposure amount up to a specific time after the shutter becomes open after driving, and if this value is less than a certain value, reduce the shutter speed command value from the middle, and also change this value. When the value exceeds a certain value, the shutter speed command value is increased midway, so that the cumulative exposure amount matches the target value when the shutter is closed. Using this method, it is also possible to correct short-term fluctuations in the light source.

FIG. 1 shows an actual system based on the principle explained above. The actual operation will be explained below using FIG.

The controller 17 contains therein optimum speed curve command data corresponding to the shutter position,
It has standard gain control data to achieve the target exposure amount. The controller 17 first sets gain control data from the target exposure amount and outputs this to the multiplier 14. Thereafter, while reading the rotational position of the shutter from the position counter 15, the optimal primary speed command value 21 is output to the multiplier 14. Due to the operation of the controller 17, the shutter rotates from the closed state to the open state and then to the closed state. After this operation, the controller 17 reads the contents of the cumulative exposure amount counter 16 and calculates gain control data 20 for realizing the optimum speed for the next exposure operation from the cumulative exposure amount actually measured in this exposure operation. ET the previously set gain control data to the G1 target cumulative exposure amount.
, if the actually measured cumulative exposure is EM and the gain control data to be calculated is G2, then

[0022]

[Formula 1] In the next exposure operation, after first outputting the obtained gain control data G2 to the multiplier 14, the controller 17 starts driving the shutter by outputting the primary speed command value 21 as in the previous time. However, the cumulative exposure amount up to a specific time after the shutter is driven is calculated by the cumulative exposure amount counter 16.
, and from this and the cumulative exposure amount at the same previous time point, gain control data 20 that achieves the target cumulative exposure amount when the shutter closes is calculated and output to the multiplier 14. Here, the cumulative exposure up to the current specific time is EN, and the cumulative exposure at the same time last time is E.
B and the gain control data to be calculated is G3.

[0023]

##EQU00002## Here, A is a constant determined by the specific time up to the intermediate cumulative exposure measurement and the shutter speed curve.

As described above, by changing the gain control data to the optimum value for each exposure operation or during the exposure operation, the cumulative exposure amount at the end of the exposure operation can be made extremely close to the target value in the shutter of the present invention. It becomes possible. Although described in detail above, the position of the shutter 3 is not limited to that shown in FIG. 1, and can be placed at an optimal position in the optical path. The timing of measuring the cumulative exposure amount after driving the shutter is not limited to one time, but is set to multiple times, and by changing the gain control data to the measurement amount, highly accurate exposure amount control can be performed.

Furthermore, in order to correct errors in manufacturing accuracy of the blades of the rotary shutter, the aforementioned gain control data is provided for each blade, thereby making it possible to control the exposure amount with high precision.

Furthermore, when first determining the gain control data, not only the target exposure amount but also the actual image plane illuminance may be measured, and the gain control data may be determined from these two data.

As another method, when the exposure time is longer than a certain time, the shutter is left open and stationary as in the conventional method, and the driving method of the present invention may be adopted only when the exposure time is shorter than the certain time. This can reduce instability caused by driving the shutter at an extremely low speed during long-time exposure.

[0028]

As explained above, according to the present invention, it is possible to increase the speed of the shutter operation compared to the conventional one in a rotary shutter configuration, and therefore, it is possible to control the cumulative exposure amount that is approximately 50% smaller. Further, in this high-speed operation, it is possible to control the cumulative exposure amount with a sufficiently high precision.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram of the present invention.

FIG. 2 is an explanatory diagram of a conventional shutter operation.

FIG. 3 is an explanatory diagram of the shutter operation of the present invention.

[Explanation of symbols]

1 Mercury lamp lamp 2 Elliptical mirror 3 Shutter 4 Lens 5 Half mirror 6 Shutter motor 7 Rotary encoder for shutter motor 8 Photodetector for measuring cumulative exposure 10 Current driver 11 FVC 12 VFC 13 Speed servo amplifier 14 Multiplier 15 Position counter 16 Total exposure Quantity measurement counter 17 Controller

Claims (3)

[Claims] 1. A rotary body having a blocking part that blocks a light flux and an opening that allows the light flux to pass, and the rotation during one exposure operation from the shutter closed state to the open state and back again to the closed state. A shutter for exposure equipment that is characterized by continuous operation without stopping the body. 2. The method is characterized in that the cumulative exposure amount is measured during the exposure operation, the optimum shutter speed is calculated based on the cumulative exposure data, and the shutter speed data is stored and retained for the next exposure operation. A shutter for an exposure apparatus according to claim 1. 3. A cumulative exposure amount is measured during the exposure operation, and a shutter speed during the exposure operation is changed based on cumulative exposure amount data within a predetermined time after the shutter is driven. Shutter for exposure equipment described in .