JPS6346728A - Lamp power control system and circuit for controlling power source for lamp - Google Patents

Abstract

PURPOSE:To keep constant illuminance on a wafer surface by arranging an illuminance sensor near the wafer surface, measuring the illuminance of the wafer surface regardless of the change of the performance of an optical part mounted into an optical path and feeding back the illuminance of the wafer surface. CONSTITUTION:Illuminance on an exposure surface at the time of the opening of a shutter 3 in the vicinity of the exposure surface is measured by an illuminance sensor 6, thus acquiring light-receiving level voltage. Voltage equal to the light- receiving level voltage in reference illuminance on the exposure surface is used as reference voltage, and differential voltage between reference voltage and the light- receiving level voltage is fed back to a power control circuit 2, thus controlling the luminous intensity of a lamp light source 1 at a fixed value. The light-receiving level voltage is renewed and memorized previously every time the shutter is opened, memory voltage is employed in place of the light-receiving level voltage at the time of opening and changed over by a changeover switch, and differential voltage with reference voltage is inputted to the power control circuit 2 and the luminous intensity of the light source 1 is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power supply control circuit for a floodlight lamp used in a projection exposure apparatus for pattern masks for IC manufacturing.

[Prior Art] In the manufacture of ICs, a method is used in which a circuit pattern of a mask of t'#"i'J is projected and exposed onto a wafer. In this case, since the width of the pattern is extremely small, it is difficult to expose the circuit pattern to a light source. A short wavelength is advantageous for UV lamps, and ultraviolet lamps are used, but in order to make accurate copies, it is important to keep the exposure amount at an appropriate constant value. There is a method in which the product of illuminance and irradiation time is constant, and a method in which both illuminance and irradiation time are constant, but the latter is more convenient in terms of control.

Next, in order to keep the illuminance at -.constant, a method is used in which an illuminance sensor is used to determine jj (4 degrees as ull+), and this is fed back to the light source lamp.

FIG. 2 shows a configuration example of a conventional lamp power supply control circuit in an apparatus for projecting and exposing a pattern mask onto a wafer. The light source lamp 1 is turned on by being supplied with an AC source input from the terminal 2a of the power control circuit 2 and controlled by ff and II. There is a shutter in the optical path. Mirror 3 is used as one, and during exposure, this is opened and the irradiated light is passed through mirror 4-1.4-
2 and then irradiated to Ueno S+FII5. ! 1 (In order to make 1 degree constant, jj (1 degree sensor 6 is placed at an appropriate place near the light source lamp 1, and its detection voltage is adjusted to an appropriate level by an amplifier (AMP) 7. The received light level voltage vra is inputted to the base voltage vs set in the rheostat 10 to the differential circuit 8 to create a difference voltage (vs-vm), and the level is adjusted by the AMP9. It feeds back to the power control circuit 2. It is during exposure, but when not exposed, the shutter 3 is closed and the control system continues to operate.

Now, mirrors 4-1 and 4-2 are arranged on the optical path 1 indicated by -1, and when some change occurs in this optical path, the illuminance of the wafer 5 changes. However, in the configuration described in 1-1, since the illuminance sensor 6 is placed on the light source side of the polisher 3, changes in the illuminance of the wafer 5 cannot be detected, and a constant illuminance cannot be maintained. This arrangement of the illuminance sensor comes from the fact that it is manufactured integrally with the light source lamp 1 and is used as is!
The placement of the IC temperature sensor 6 should be changed to be closer to the wafer 5. However, it cannot be replaced with moist heat. The reason for this is that when the illuminance sensor 6 is placed near the wafer 5, the light received by the illuminance sensor 6 changes dramatically each time the shutter 3 is opened or closed, and the light source lamp 1 is not adjusted to the specified level regardless of whether the shutter 3 is opened or closed. The control system works to output power. In other words, even though the amount of fluorescence from the illuminance sensor 6 is extremely low when the light source 3 is closed at 11.4, the light i from the light source lamp 1 increases unnecessarily, and the lamp life is shortened. This will lead to deterioration or damage.

Furthermore, when the illuminance sensor 6 is placed near the wafer 5, the light 6:(
The power supplied to the lamp 1 must be controlled so as not to fluctuate. - Generally speaking, changes in power are a source of stress for lamps, and even if the changes are not drastic as described above, changes in the number of lamps will affect the lamp's lifespan. The important point is that when the luminous intensity of the light source lamp 1 changes each time the shutter 3 is opened and closed, transient fluctuations occur in the luminous intensity. Recently, there has been a trend to increase the luminous intensity and shorten the exposure time in order to increase the raw pressure effect, but the shorter the exposure time, the more harmful the fluctuations in the luminous intensity are.

What is desired is a lamp power supply control method and control circuit that eliminates the disadvantages of the conventional method described below by υ1, eliminates transient fluctuations such as fluctuations in the illuminance of the wafer, and allows the light source lamp to operate safely. .

[Object 1-1 of the invention] This invention solves the above-mentioned drawbacks of the conventional lamp power control system in a mask pattern exposure apparatus, and makes it possible to control the illuminance of the wafer without transient fluctuations, regardless of whether the shutter is opened or closed.
・Objective 1-1 is to provide a lamp electric αI:l, 11 control system and control circuit that can maintain a constant value and safely operate a light source lamp.

[Means for Solving the Problems] In the lamp power control system according to the present invention, in a lamp light source with a gloss that irradiates an exposed surface, a lamp light source on the exposed surface when the gloss is opened is placed in the vicinity of the exposed surface.
! (1 degree is measured 1:1 by an illuminance sensor to obtain a received light level voltage, and a voltage equal to the received light level voltage at the reference illuminance of the exposure surface is set as a reference voltage Il-, and the reference voltage and [-
The luminous intensity of the lamp light source is controlled to a constant value by feeding the voltage difference between the recorded light level voltage and the received light level voltage to a power control circuit.

In addition, when the shutter is opened, the light reception level voltage is updated and stored, and the stored voltage is used as a substitute for the light reception level voltage when the shutter is opened, and is switched by a changeover switch. The voltage difference from the reference voltage is input to the [-2 power control circuit for control.

Next, in the lamp power supply control circuit according to the present invention,
An illumination sensor for measuring the illuminance on the exposure surface is arranged near the exposure surface, and a storage circuit is provided for updating and storing the received light level voltage based on the characteristic of opening of the shutter obtained by the illuminance sensor.

Furthermore, there is a detector for detecting a drop in the received light level voltage when the gloss is closed, a changeover switch operated by the output voltage of the detector, and a switch that detects the received light level voltage of the illuminance sensor and the shutter when the gloss is opened. At the time of closing, 1. a difference circuit that switches the memory voltage stored on the memory circuit by the changeover switch and outputs each difference voltage from the reference voltage, and the difference circuit; Input the voltage and reduce the power supplied to the lamp light source by 1 so that the exposed surface has the reference illuminance of 10.
It is composed of a power control circuit that controls the

[Function] In the lamp power supply control method and control circuit according to the present invention, +! Since the i degree sensor is placed close to the exposed surface, the influence of a 1 degree change in jj (1 degree) on the exposed surface due to changes in mirrors etc. installed in the optical path is removed, making it possible to control illuminance that matches the actual situation. However, when the shutter is closed, the output voltage of the illuminance sensor drops to nearly zero, so this is detected by the detector and its signal is
Toggle the switch. The received light level voltage is updated and stored in the shutter opening characteristics, and after the above switch is changed, that is, at 11 o'clock when the shutter is closed, a difference voltage is created between this stored voltage and the base voltage, and the voltage is applied to the power control circuit. input. As a result, even when the glossy vine is closed,
Power is supplied to the lamp optical gap in the same state as when the lamp is open.

[Example 1] FIG. 1 is a circuit configuration diagram of an embodiment of the lamp power control system and control circuit according to the present invention. and is ignited.

When the glossy 3 is open, the irradiated light is reflected on the mirror 4-1゜4-
The light beam is reflected by the beam 2, changes the optical path, and irradiates the wafer 5.

An illuminance sensor 6 is placed near the wafer 5 at a position that exhibits the same illuminance as the wafer 5.

The output voltage of the illuminance sensor 6 is adjusted to an appropriate level by the AMP 7, and is made into the received light level voltage Vll, which is inputted to the terminal of the differential circuit 8 via the terminal A of the analog switch 12. On the other hand, the basis of wafer 5/vi! ! (The light reception level voltage of the illuminance sensor 6 with respect to 1 degree is taken as the base voltage VS, and this reference voltage VS is set by the rheostat 10 and FJ is connected to the other terminal of the differential circuit 8. The voltage difference 11.= is output.The difference voltage is AMP
9, the signal is converted to an appropriate level and input to the power control circuit 2. Now, during exposure, when the illuminance of the wafer 5, that is, the illuminance sensor 6, decreases, the received light level voltage vm
decreases, and the base voltage t also becomes the difference voltage (vs −v
Since m) increases to a positive value, the power control circuit 2 acts to increase the power supplied to the light source lamp 1, and the illuminance of the wafer 5 increases. Also, on the contrary! 1 (When the illuminance of the sensor 6 increases once, the differential voltage (
vs - vm ) increases with a negative value, the power of the light source lamp 1 decreases, and the illuminance of the wafer 5 is kept constant.

Next, we will discuss the blasphemy in closing 1111 of the glossy 3. At this time, the received light level voltage VI11 drops to nearly zero, so this is detected by the detector 11 at an appropriate comparison voltage vr.
Then, the analog switch 12 is switched to the end J'B side using No. 1. A voltage that is different from the received light level voltage vm is applied to this terminal B by IJ.

In order to achieve
is applied to the voltage v through the digital volute 14.
m', and the terminal γB of the analog switch 12 and the terminal of the differential circuit 15! j, er. The light reception level voltage vm of the output of the AMP 7 is applied to the other terminal of the differential circuit 15, and the difference voltage between the two is adjusted by 1 to an appropriate level by the AMP 18 and inputted to the counter control circuit 17. do. In the counter control circuit 17, the differential voltage (v+a-
vm') to adjust the amount of attenuation of the digital volume 14, and perform self-control so that the differential voltage (ym-vm') becomes zero. As a result, the output voltage vm° of the digital volume l, 14 becomes equal to the light reception level voltage vm. Therefore, at Kanshoj + ¥ of shutter 3,
The voltage V1 of the digital voltage 14 is given to the differential circuit 8 from f+t4R B of the analog switch 12.
Since this is equal to the light reception level voltage at the time of the previous open circuit, the power control circuit 2 has the same differential voltage (v
s -vn+) is given by '-j, and the power supplied to the lamp light source 1 remains unchanged. In addition, such self-control is performed each time the shutter 3 is opened and closed, and it always follows the received light level voltage vm when the IJ is opened. The iE light intensity is also maintained.

Note that the circuit including the differential circuit 15, counter control circuit 17, and digital volume 14 may be any other circuit as long as it can update and store the received light level voltage vm and output it when the shutter 3 is closed. be.

[Effects of the Invention] As is clear from the explanation in Part 1, in the lamp light source control method and control circuit according to the present invention, since the *i degree sensor is placed near the wafer, Changes in the performance of optical components such as mirrors! By measuring the degree of 1; 1 (The absolute value of 1 degree is measured, which is convenient for management. Also, when the shutter is closed, the received light level voltage at the time of opening immediately before is used.)
Since the power of the lamp light source is maintained in the same state as when it is opened, transient fluctuations in the lamp brightness are completely eliminated when the lamp is opened and closed.Furthermore, the lamp light during use; (Even if the light intensity changes due to deterioration of the lamp or replacement of the lamp light source, a constant illuminance is maintained, and a constant and accurate illuminance can be provided to the exposed surface. At the same time, the stress caused to the lamp light source is This invention is highly effective for mask pattern exposure equipment, as it is also effective in maintaining lamp life.This invention is applicable not only to mask pattern exposure equipment, but also to other similar lamp light sources. Needless to say, it is applicable.

[Brief explanation of drawings]

FIG. 1 shows a lamp power supply control method according to the present invention and;
FIG. 2 is a circuit configuration diagram of an embodiment in which the control circuit is applied to a mask pattern exposure apparatus. FIG. 2 is a circuit configuration diagram of a conventional lamp electric 91 control circuit in a mask pattern exposure apparatus. 1... Light source lamp, 2... Power control circuit,
2a...A C+XJ J"% 3"・
Shutter, 4...Mirror, 5...'7
Eva, 6... illuminance sensor, 7+ 9.
IG...AMP18.15...Differential circuit,
10.1:)... Rheostat, 11... Detector, 1
2...Analog switch, 14...Digital volume l1.17...Counter control circuit, VS...Reference voltage, vm...Light receiving level voltage 1, ",vm゛・
...Digital volume output voltage, v7...Constant voltage % Vr...Comparison voltage.

Claims (2)

[Claims] (1) In a lamp light source with a shutter that irradiates the exposed surface, an illuminance sensor installed near the exposed surface measures the illuminance on the exposed surface when the shutter is open to obtain the light reception level voltage, and The light receiving level voltage at the reference illuminance of the exposure surface is used as a reference voltage, and when the shutter is open, the luminous intensity of the lamp light source is controlled by feeding back the difference voltage between the reference voltage and the light receiving level voltage to the power control circuit. is controlled to a constant value, and when the shutter is closed, a storage voltage of the received light level voltage that is updated and stored each time the shutter is opened is switched by a changeover switch in place of the received light level voltage. ,
A lamp power supply control method, characterized in that the luminous intensity of the lamp light source is maintained constant by inputting a voltage difference between the storage voltage and the reference voltage to the power control circuit. (2) In a lamp light source with a shutter that illuminates the exposed surface, an illuminance sensor that measures the illuminance on the exposed surface is provided near the exposed surface, and the light received by the illuminance sensor every time the shutter is opened. A detector is provided with a memory circuit for updating and storing the level voltage, and detects a drop in the received light level voltage when the shutter is closed; a changeover switch operated by an output signal of the detector; a differential circuit that outputs a voltage difference between the received light level voltage of the illuminance sensor and the reference voltage by switching the storage voltage stored in the storage circuit when the shutter is closed using the changeover switch; A lamp power supply control circuit comprising a power control circuit that inputs the differential voltage and controls power supplied to the lamp light source so that the illuminance of the exposure surface becomes the reference illuminance.