JP2793050B2 - Exposure equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus used in a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art Generally, an exposure apparatus for a semiconductor manufacturing apparatus is a short arc type mercury discharge lamp (hereinafter simply referred to as a lamp).
And a power supply device for lighting this lamp with direct current. As a light source device, for example,
An apparatus as disclosed in Japanese Patent Application Laid-Open No. 2-185319 is used.
439.

In the light source device described above, the intensity of irradiation from a lamp to a semiconductor wafer is increased in order to improve productivity in a production line. In addition, the power supply also detects power, current, and voltage to maintain this irradiation intensity constant,
Feedback control.

[0004]

In such an exposure apparatus, it is necessary to cool the bulb of the lamp. This cooling includes natural air cooling and forced air cooling, but in any case, if the cooling state changes, an arc (electric arc) generated between the electrodes of the lamp is displaced. Such a state is shown in FIGS. In FIG. 1, 1 is a valve, 2 is a seal portion,
Reference numeral 3 denotes an anode, 4 denotes a cathode, and 5 denotes an arc (an arc, in this case, a short arc). If the entire valve is uniformly cooled by natural or forced air, the arc will
And the cathode 4 at the shortest distance. On the other hand, if the air cooling is not uniform, an arc is formed along the inner wall of the bulb 1 as shown in FIG. When this occurs, the valve will devitrify or burst. In addition, since the arc length becomes long, an unexpected increase in the lighting voltage occurs when the normal lighting is used.

According to the present invention, when the position of such an arc becomes abnormal, the power supply to the lamp is stopped,
Another object of the present invention is to provide an exposure apparatus capable of reducing the number of exposures.

[0006]

In order to solve such an object, a discharge lamp lighting device according to the present invention comprises a short arc-type mercury discharge lamp housed in a lamp house, in a state of natural air cooling or forced air cooling. In an exposure apparatus comprising a light source device that performs direct current lighting and a power supply device that lights the mercury discharge lamp, the power supply device includes a main lighting circuit including a switching circuit, and a unit that detects a lighting voltage of the mercury discharge lamp. A control circuit that compares a signal from the detection means with a reference value and feeds back the feedback signal to a switching circuit, wherein the control circuit determines that the detection means is at least +5 V above the rated voltage of the mercury discharge lamp. And when detecting a state where the state is continued for one second or more, works to turn off the mercury discharge lamp or reduce the supplied power. A means for detecting an abnormal discharge state between the electrodes to be applied when +5 V or more from the rated voltage continues for 1 second or more, and means for turning off the discharge lamp or reducing the supply power based on the detection means. Features.

[0007]

With such a configuration, when the detecting means for detecting the lighting voltage of the lamp is equal to or higher than the rated voltage of +5 V and further detecting that this state is continued for more than one second, the power supply to the lamp is determined. To stop or reduce. Thus, devitrification and rupture of the bulb due to abnormal arc discharge can be prevented.

[0008]

The present invention will be specifically described below with reference to examples. FIG. 3 is a schematic circuit diagram of the exposure apparatus of the present invention. FIG. 4 is a diagram showing a change in the lighting voltage from when the discharge lamp is turned on until it becomes stable. In the figure, reference numeral 31 denotes a short arc type (short arc type) ultra-high pressure discharge lamp, which has a rated voltage of 20 V and a rated power of 2 kW, for example. (Hereinafter, it is simply referred to as a lamp.) Then, this lamp 31 is DC-lit. 32 is an AC power supply. And AC power supply 3
2 is connected to a switching circuit 33. Although the type of the switching circuit 33 is not particularly limited, for example, a half-bridge type is applied. A transformer 34 is connected to the switching circuit 33. The secondary side has a rectifying diode D1 and a smoothing capacitor C1.
1, and the lamp 31 is connected via the starter 40. In this case, the switching circuit 33, the transformer 34, the diode D1, and the capacitor C1 are referred to as a main lighting circuit.

The lighting voltage of the lamp 31 is detected from a detection point A and input to a comparator 38. This is referred to as detection means. The comparator 38 compares the detected voltage signal with a reference value of the reference device 39. In this case, the reference value is + 5V of the rated voltage.
Is set to When this reference value is exceeded, the output is input to the integrator 37. Although not shown, the integrator 37 is constituted by a time constant circuit of a resistor and a capacitor. This time constant is set to one second. When the signal from the comparator 38 exceeds the set value of 1 second, the integrator 37
Is input to a pulse width modulation circuit (PWM) 36. Further, the switching circuit 33 is driven by a drive circuit 35 connected to the output of the PWM 36. That is, the lighting voltage of the lamp 31 is +5 V of the rated voltage.
For one second, the lamp 3
1 to stop or reduce the power supply. The comparator 38, the reference unit 39, the integrator 37, the PWM 36, and the drive 35 are collectively referred to as a control circuit.

FIG. 4 shows a change in the lighting voltage after the lamp 31 is turned on. When a high voltage is applied by the normal starter 40, the impedance between the electrodes sharply drops and lighting starts. About 0.4-0.6 from this state
During the second, the lighting voltage fluctuates significantly and is extremely unstable. Thereafter, when the operation is shifted to stable lighting, the lighting voltage does not change. On the other hand, the abnormal discharge state between the electrodes, which is a problem of the present invention, is not so problematic for a short time. Therefore, at the start of lighting, the present invention sets a time of about 1 second so as not to detect an unstable state of the lighting voltage in 0.4 to 0.6 seconds.

On the other hand, when the lamp 31 is used for a long time, the lighting voltage gradually increases due to wear of the electrodes and the like. This is considered to be because the distance between the electrodes is long. However, when the amount of light is about 70% of the initial light amount after about 500 hours of use, the voltage rises by about 2 to 3 V. At this time, the arc is not an abnormal discharge that draws an arc. Therefore, +5 V is set to distinguish this phenomenon. By such control, the lighting of the lamp can be satisfactorily controlled without being affected by the air-cooled state. In this embodiment, the light source device is omitted, but the light source device is described in Japanese Patent Application Laid-Open No.
19. The one disclosed in JP-A-62-54439 is applied.

[0012]

As described above, according to the exposure apparatus of the present invention, an abnormal discharge state of an arc generated between electrodes can be detected satisfactorily without being mistaken for other states. Therefore, rupture or devitrification due to local heating of the sealing body can be prevented.

[0013]

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a state when a normal discharge is performed.

FIG. 2 is an explanatory diagram showing a state when abnormal discharge occurs.

FIG. 3 is a schematic circuit diagram of a lighting device of the present invention.

FIG. 4 is a diagram showing a relationship between lighting voltage and time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Enclosure 2 Sealing part 3 Anode 4 Cathode 5 Arc 31 Discharge lamp 32 AC power supply 33 Switching circuit 34 Transformer 35 Drive 36 PWM 37 Integrator 38 Comparator 39 Reference device 40 Starter

Claims (1)

(57) [Claims] 1. An exposure apparatus comprising: a light source device for accommodating a mercury discharge lamp of a short arc type in a lamp house for direct-current lighting under natural or forced air cooling; and a power supply device for operating the mercury discharge lamp. A main lighting circuit including a switching circuit, a means for detecting a lighting voltage of the mercury discharge lamp, and a control circuit for comparing a signal from the detecting means with a reference value and feeding back the signal to the switching circuit. And the control circuit comprises:
The detecting means is configured to increase the voltage of the mercury discharge lamp by +
An exposure apparatus that functions to turn off the mercury discharge lamp or reduce the supply power when detecting a state of 5 V or more and that state is continued for 1 second or more.