JPS622428B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a mercury rare gas discharge lamp and a lighting method thereof. Recently, with the development of VLSI, printing and transfer technologies with processing accuracy of 1 micron or less have become required. Conventional technology, in which machining accuracy of 1 micron or more is sufficient, has already been put into practical use by using discharge lamps that emit ultraviolet rays of 350 nm to 450 nm and photosensitive resins that are sensitive to that wavelength. , if precision of 1 micron or less is required, the conventional techniques cannot be used due to optical interference. For this reason, research and development into electron beam exposure and X-ray exposure was carried out at a rapid pace to replace discharge lamps, but while they had the advantage of being able to automate printing and transfer and simplify processes when used in conjunction with a computer, The disadvantage of long exposure time is said to be fatal, making it extremely impractical. For this reason, a combination of a discharge lamp and an ultraviolet-sensitive resin has been considered again. That is 300n
Studies have begun to examine whether it is possible to obtain resins that are sensitive to ultraviolet rays of wavelengths below 500 m and discharge lamps that emit a large amount of light at that wavelength. Fortunately, in 1974, photosensitive resin for electron beams was developed.
PMMA is sensitive to light below 200nm (Applied
Physics Letter Vol. 25, p. 451), 200n in 1975
Similarly, PMMA can be used for transfer using ultraviolet light of m ~ 260 nm (J.Vac.Sci Technol Vol.12, 1317
Page) were clarified one after another through experiments. Therefore, the inventor researched a light source that emits a large amount of ultraviolet light at a wavelength that does not cause optical interference, has good processing accuracy, and shortens the time required for printing and transfer, and found that (a) it is the best light source for printing and transfer. (b) A mercury rare gas discharge lamp, in which mercury and a rare gas contribute to discharge luminescence, is suitable for discharge luminescence; (c) In this discharge lamp, the bulb internal volume is 1 c. When the value of the amount of mercury (mg/cc) per c. It was found that significantly more products were obtained. Regarding (c) above, please refer to the patent application dated December 23, 1978 (Patent Application No. 153515 ``Discharge Lamp'')
As detailed in No. 86979)), it was found that there is room for further improvement in relation to the printing method. Normally, IC, LSI, and even super
When using a technology that combines a light source and a photosensitive resin for printing or transferring LSI, if you want to shorten the printing time, you should use a light source with a high light output. For example, if you are using a mercury rare gas discharge lamp with a rated power consumption of 500W and it takes 30 seconds to bake, but you want to make it 15 seconds, you would use a mercury rare gas discharge lamp with a rated power consumption of 1KW. However, in mercury rare gas discharge lamps that emit a large amount of 200nm to 250nm, even if the rated power consumption is doubled, the amount of radiation in the 200nm to 250nm range is not doubled, but is at most 1.5 times, and the burnout time is It turns out that it is not necessarily halved. Therefore, in addition to simply increasing the rated power consumption, we researched a mercury rare gas discharge lamp suitable for burning in a short time and its lighting method, and found that when the volume of the anode is defined within a predetermined range,
We discovered that increasing the amount of radiation between 200nm and 250nm can prolong the lamp life, and that it is better to keep the lamp lit at a constant DC current with a predetermined rated power consumption, and then superimpose an over-input discharge on top of that. Thus, the present invention was completed. That is, the present invention provides a mercury rare gas discharge lamp that is suitable for baking semiconductors in a short time, emits a large amount of ultraviolet rays of 200 nm to 250 nm with low power consumption, and has a long lamp life, and a lighting method thereof. The purpose and characteristics of the valve are that the internal volume of the valve is 1 c.c.
When the value of the amount of mercury per unit (mg/cc) is X and the value of the rare gas pressure (atmospheric pressure) is Y, 1≦X≦13, 0.1≦Y
≦10, and the anode of a mercury rare gas discharge lamp that is lit with a maximum of 300% intermittent over-input superimposed power is defined as described in claim 1, and further lit by the method described in claim 2. It's about doing. Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Fig. 1 is an explanatory diagram of a short electric arc discharge lamp for direct current lighting filled with mercury and rare gas, and shows a foil seal type discharge lamp, 1 is a quartz bulb roughly shaped like a rugby ball, 2 and 3 are 4 and 5 are metal foils embedded in the hermetic sealing parts 2 and 3, respectively; 6 and 7 are inner conductors extending from the metal foils 4 and 5 respectively into the quartz bulb; one of the inner conductors An anode 8 is attached to the tip of the inner conductor 6, and a portion 9 (shaded portion) of the other inner conductor 7 located inside the bulb functions as a cathode. FIG. 2 is an explanatory diagram of a similar discharge lamp, showing a rod seal type discharge lamp, with an anode 8 and a cathode 9.
are supported by lead rods 10 that hermetically pass through the hermetically sealed portions 2 and 3, respectively. The discharge lamp with the structure shown in Figure 1, designed for data collection, has a rated power consumption of 500 watts, a rated operating voltage of 24.3 volts, and a rated operating current of 20.5 amperes. ,
We also compared this with a case in which discharge due to intermittent over-input was further superimposed. Here, “rated” means
This is a usage standard in which the lamp performance remains within a certain range even if the lamp is lit continuously at a constant power.
400 to make the radiation output at 250nm 70% of the initial value.
The power, voltage, and current values are determined so that the discharge lamp has a service life of 1 hour, and these values are referred to as rated power consumption, rated operating voltage, and rated operating current. Figures 3a, b, and c are explanatory diagrams of various methods for superimposing discharges of intermittent over-input, respectively; in the case of a, the rated power consumption is assumed to be 100%;
Leave it on in that state, and then turn it on to the maximum
Example of superimposing a 10-second intermittent over-input discharge at 300% with a superimposition interval of 20 seconds, twice the intermittent over-input discharge time, and inputting 1500 W, which is three times the rated power consumption. It is. In case b, in order to sharpen the "rise and fall" of the discharge due to intermittent over-input in case a, a low input part t (dark part) of several milliseconds is provided before and after the intermittent over-input. In the case of , c, if the "standby lighting" is set at a power consumption lower than the rated lighting, as is the case with the lighting method of the xenon light source device for movie projectors, and then the superimposed discharge similar to the case of a is applied. Both are characterized by the fact that they are kept lit at a constant DC current and then discharged due to intermittent over-input. Incidentally, the baking time for semiconductors varies widely depending on the resin material used, from less than one second to several tens of seconds, but in principle baking should be completed within the time of one excessive input. Therefore, we investigated the change in the increase in ultraviolet light intensity with respect to the over-input time and determined the optimal over-input discharge time. The discharge lamp used has a rating of 500W as mentioned above, and the amount of mercury (X) filled is 6.7
mg/cc (25℃), rare gas (xenon) pressure (Y)
is 3 atm (25°C), and the results when the input is 200% and 300% are shown in Figure 4. As you will see,
The intensity of ultraviolet rays increases significantly when the discharge time of excessive input is 0.1 seconds, remains at almost the same level for the next 60 seconds, and then gradually decreases. Therefore, this discharge time is 0.1
Ultraviolet rays can be emitted efficiently by controlling the time to ~60 seconds. And the increase rate at 200% input is 80%
From the above, it is understood that conventional rated continuous lighting is more effective than simply doubling the power consumption, which increases the rate of increase by at most 1.5 times (50% increase). Furthermore, when the input is increased to 300%, the amount increases by 200%. However, if the magnitude of the input exceeds 300% of the rated value, it is undesirable because blackening and damage of the quartz bulb will occur at an early stage. Next, we prepared six types of discharge lamps with different amounts of mercury (X) and rare gas pressures (Y) in the bulbs, and
We investigated the influence of The results are shown in Table 1, with two levels of input, 200% and 300%, including a reference example in which the lamp was lit continuously at the rated power without excessive input.

[Table] The bulb is sealed so that the sum of the mercury pressure and the rare gas pressure is almost constant, so if the amount of one increases, the amount of the other decreases.In discharge lamp No. 1, Y Even if it was 0.1, the number of X was as high as 15, so it was not exposed and could not be used. On the other hand, in discharge lamp No. 6,
Even when Y is 1.0, Y is as large as 12, so the amount of ultraviolet radiation is insufficient and the baking time becomes long, making it impractical. In contrast, discharge lamps
For No. 2 to No. 5, 1.0≦X≦13, 0.1≦Y≦10, and although there are slight differences depending on the discharge lamp No., all of them can burn out in a short time. It turned out that it is fully practical. Therefore, the lower limit of the value of Y has become wider than conventionally, where 1≦X≦13 and 2≦Y≦10 were considered good.
This is true for normal rated continuous lighting when Y < 2.
The radiation of ultraviolet rays in the range of 200 nm to 250 nm is small, and the baking time is not shortened, but if the above-mentioned controlled lighting is performed as in the present application, the above ultraviolet rays increase, and Y = 0.1.
It was found that this method was effective in shortening the printing time. In this way, the discharge lamp of the present application performs discharge with intermittent over-input, which places a burden on the anode, and an anode of the same size as a conventional rated continuous lighting model suffers from severe damage, shortening the lamp life. There is a point. Therefore, the lamp life was investigated by changing the anode volume (Z) per rated power consumption. The discharge lamp used was the same as the one used in the above-mentioned investigation of the influence of over-input time, with two levels of input, 200% and 300%, and two levels of over-input time, 200 msec and 400 msec (the over-input interval is both Figure 5 shows the results obtained when the light was turned on under the condition of 400 msec). As you will see,
The larger the input and the longer the overload time, the shorter the electrode life tends to be, but at any level, when Z is between 0.05×10 ^-3 cc/W and 0.1×10 ^-3 cc/
The life span rapidly increases as the temperature approaches W, and thereafter increases gradually until reaching saturation above 0.6×10 ⁻³ cc/W. At 300% input, which is the most severe condition, Z is 0.1×10 ^-3 cc/W no matter what the overload time is.
The life is about 200 hours when Z≧0.1×10 ^-3
If it is cc/W, a lamp life that can withstand practical use can be obtained. On the other hand, if the value of Z is increased unnecessarily, the surface area of the electrode will increase, and the amount of infrared radiation will increase. For example, if the volume increases by 20%
Radiant energy for wavelengths longer than 500nm is approximately 0.05W
However, as the radiant energy of infrared rays increases, the temperature of the semiconductor wafer rises and expands, resulting in a problem that exposure accuracy decreases. Furthermore, due to the increased weight of the electrodes, foil-sealed lamps have problems in that the center of the electrodes may shift during the sealing process, or the foil may break if the sealing process is too severe. Therefore, in order to prevent these problems from arising, as a result of various investigations, the upper limit of Z is 0.5×10 ^-3
It turned out to be cc/W. As explained above, in the lighting method of the present invention, X and Y are defined as 1≦X≦13, 0.1≦Y≦10, and after lighting is performed at a constant DC current, further discharging due to intermittent over-input. is superimposed, and the discharge time of the excessive input is set to 0.1
Since it is controlled within ~60 seconds, it efficiently emits radiation in the range of 200 nm ~ 250 nm, which has the advantage of shortening the time required for printing and transferring semiconductors such as ICs, LSIs, and super LSIs. Further, the discharge lamp of the present invention is also suitable for semiconductor manufacturing, and has a 0.1×
Since it is specified as 10 ^-3 ≦Z≦0.5×10 ^-3 , problems due to the electrode being too large do not arise, and the lamp life can be extended despite superimposing excessive input. .

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams of a discharge lamp, FIG. 3 is an explanatory diagram of a method of lighting a discharge lamp, and FIGS. 4 and 5 are explanatory diagrams of experimental data. 1...quartz bulb, 8...anode, 9...cathode.

Claims (1)

[Claims] 1. A mercury rare gas discharge lamp comprising an anode and a cathode disposed in a bulb and containing mercury and a rare gas,
When the amount of mercury (mg/cc) per 1 c.c. of valve internal volume is X, and the rare gas pressure (atmospheric pressure) is Y, it is defined as 1≦X≦13 0.1≦Y≦10 At the same time, the volume of the anode is 0.1×10 ^-3 ≦Z≦0.5× when the volume of the anode is Z (cc/W) relative to the rated power consumption of the discharge lamp, when the lamp is lit with a maximum of 300% intermittent over-input superimposed power. 10 ^-3 A mercury rare gas discharge lamp. 2. For a mercury rare gas discharge lamp, which has an anode and a cathode inside the bulb and contains mercury and a rare gas,
When the value of the amount of mercury (mg/cc) per 1 c.c. of valve internal volume is X, and the value of rare gas pressure (atmospheric pressure) is Y, specify 1≦X≦13 0.1≦Y≦10, After turning on the DC constant current light,
A method for lighting a mercury rare gas discharge lamp characterized by further superimposing discharge of an intermittent over-input of up to 300% and controlling the discharge time t of the intermittent over-input to 0.1 seconds to 60 seconds.