JP4235814B2 - Flash discharge lamp - Google Patents

Description

  The present invention relates to a flash discharge lamp using a sapphire tube which is a kind of flash discharge lamp used for a light source for thermal annealing of a silicon wafer.

Conventionally, lamp annealing is used in a process of activating a so-called ion-implanted impurity that forms a shallow diffusion layer (pn junction) in a surface layer of a silicon wafer in a manufacturing process of a semiconductor or the like. In such an annealing process, it is to obtain a good activation state for the impurities while avoiding problems such as a collapse of the profile of the implanted ions and volatilization of the formed pattern. Also, in the manufacturing process of thin film transistors for liquid crystal display panels, it is necessary to reliably and uniformly activate the semiconductor film formed on the substrate. It is necessary to prevent excessive heating of the glass substrate and to suppress the expansion and contraction and warpage of the glass substrate.
As such an annealing technique, one disclosed in Japanese Patent Application Laid-Open No. 2002-198322 is known.

In general, in order to perform lamp annealing on a semiconductor substrate, it is necessary to raise the temperature from 1000 ° C. to 1400 ° C. and heat it. Specifically, light having an energy of 30 J / cm ² or more is irradiated to a semiconductor substrate as an irradiation object in a short time of 700 μs. At this time, since the peak energy input to the flash discharge lamp reaches 5 × 10 ⁶ W, the flash discharge lamp is forced to light under severe conditions.

  Conventionally, quartz glass has been mainly used as the arc tube material of flash discharge lamps. However, when the lamp is lit under the above severe lighting conditions, the inner surface of the arc tube becomes cloudy and the illuminance on the irradiated surface is extremely high. Problems occur.

  The white turbidity on the inner surface of the arc tube is also related to the pulse width when the flash discharge lamp is turned on, that is, the time width at half the peak value of the flash pulse waveform. When the pulse width is shortened, the temperature of the plasma increases and the peak intensity of light increases. In particular, in order to perform lamp annealing on a silicon wafer, it is desirable to make the pulse shorter because the better results are obtained with respect to the object to be processed with a shorter pulse width. For example, the pulse width is 300 μs. When the lighting is performed with a short pulse width as described below, the inner surface of the arc tube is abnormally heated, causing a problem of further clouding.

  That is, in lamp annealing, it is desirable to shorten the pulse because lighting with a short pulse width gives better results for the object to be processed. However, flash discharge using a quartz glass arc tube is desirable. This is not possible with a lamp.

  Therefore, in recent years, a flash discharge lamp using a translucent alumina tube, particularly a flash discharge lamp using a sapphire tube made of single crystal alumina, has attracted attention. In the flash discharge lamp using the alumina arc tube, unlike the conventional quartz glass arc tube, the arc tube becomes clouded even when the pulse width is 300 μs or less, for example, 200 μs. There is no.

  As a flash discharge lamp using translucent alumina for an arc tube, one disclosed in Japanese Utility Model Laid-Open No. 63-60265 is known, which is a seal at the end of a translucent alumina tube. The (sealing) structure employs a so-called metal seal structure in which the outer surface of the end of the arc tube is metallized and the metal cap is hermetically closed with a metal solder at the metallized part.

In addition, as a discharge lamp using translucent alumina as an arc tube, there are a high-pressure sodium lamp, a metal halide lamp, and the like. A lamp having an alumina arc tube of this kind is a translucent alumina arc tube. A so-called ceramic seal structure in which a heat-resistant metal cap or a ceramic cap and a conductor are hermetically sealed with frit glass (frit glass) is adopted at both ends of the opening. As one using such a ceramic seal, one disclosed in Japanese Patent Laid-Open No. 53-108682 is known.
JP 2002-198322 A Japanese Utility Model Publication No. 63-60265 JP-A-53-108682

  However, when a metal seal is used as a hermetic sealing method for a flash discharge lamp using a sapphire arc tube, when a lamp is lit, a peripheral member such as a mirror is applied from the metal seal portion by applying a trigger voltage. Otherwise, abnormal discharge may occur in the lamp holder and the seal part may be damaged, causing a problem of non-lighting.

  Further, when a flash discharge lamp is used as a light source for thermal annealing of a silicon wafer, a plurality of lamps are lit as disclosed in JP-A-2002-198322. In that case, electric discharge occurs in the adjacent metal seal portion, and the seal portion often breaks, and cannot be used.

  On the other hand, when a ceramic seal is used as the sealing method, the main constituent member of the seal portion is made of an insulator, so that the seal portion is not damaged by the abnormal discharge as described above. However, even when a ceramic seal is used, when a certain type of frit glass is used, there is a problem that the ceramic sealed part is damaged or the illuminance maintenance rate of the lamp is lowered while the lamp is repeatedly lit. Was.

  An object of the present invention is to provide a flash discharge lamp that uses a sapphire arc tube to prevent the occurrence of defects at a ceramic-sealed portion.

The present invention employs the following means in order to solve the above problems.
The first means is a flash in which both ends of the sapphire arc tube are hermetically sealed by an alumina closing member in which an electrode member made of niobium, tantalum or kovar alloy is hermetically penetrated and held. In the discharge lamp, a first frit glass is used for hermetically sealing between the electrode member and the closing member, and for sealing hermetically between the closing member and the sapphire arc tube. The first frit glass has a glass transition point of 450 to 800 ° C., and the second frit glass has a glass transition point lower than the glass transition point of the first frit glass. Tendea is, the first frit glass is the linear expansion coefficient at 300 ℃ (7 ± 2) × 10 -6 / K, the second frit glass has a linear expansion coefficient (7 1) it is a flash discharge lamp which is a × ¹⁰ -6 / K.

Second means, in the first means, before Symbol second frit glass, a flash discharge lamp, wherein the content of zinc oxide is 20% or less.

According to the first aspect of the present invention, the both-end openings of the sapphire arc tube are hermetically sealed by the alumina closing member in which the electrode member made of niobium, tantalum, or Kovar alloy is hermetically penetrated and held. In the sealed flash discharge lamp, a first frit glass is used to airtightly seal between the electrode member and the closing member, and an airtightness is provided between the closing member and the sapphire arc tube. The first frit glass has a glass transition point of 450 to 800 ° C., and the second frit glass has a glass transition point of the first frit glass. glass transition temperature der lower than is, the first frit glass is the linear expansion coefficient at 300 ℃ (7 ± 2) × 10 -6 / K, the second frit glass Since the linear expansion ratio is (7 ± 1) × 10 -6 / K, to prevent breakage of the portion to be ceramic sealed, it is possible to improve the illuminance maintenance factor of the lamp, heating and cooling during the sealing It is possible to prevent the occurrence of cracks in the ceramic sealed portion in the process .

According to the invention described in claim 2, wherein the second frit glass, since the content of zinc oxide is 20% or less, even lit 100,000, to ensure the illuminance maintenance factor of 70% Can do.

An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a cross-sectional view of a flash discharge lamp according to the invention of this embodiment.
In the figure, 1 is a flash discharge lamp, 2 is an arc tube made of sapphire, 3 is a closing member made of alumina, 4 is an electrode made of tungsten, 5 is made of any conductor such as niobium, tantalum, rhenium, or kovar alloy. 6 is a first frit glass for sealing between the closing member 3 and the electrode member 5, 7 is a second frit glass for sealing between the arc tube 2 made of sapphire and the closing member 3, 8 is a lead wire, A Is a sealing portion of the closing member 3 through which the electrode member 5 is held, and B is a sealing portion in which both end openings of the sapphire arc tube 2 are hermetically sealed by the closing member 3.
An example of the dimensions of the flash discharge lamp 1 is one having an outer diameter of 13 mm and an inner diameter of 10.4 mm. A sapphire arc tube 2 is filled with 60 kPa of xenon gas.
Here, the first frit glass has a linear expansion coefficient at 300 ° C. of ( 7 ± 2 ) × 10 ⁻⁶ / K, and the second frit glass has a linear expansion coefficient of ( 7 ± 1 ) × 10 ^−6. / K.
When frit glass whose linear expansion coefficient is not included in the range of ( 7 ± 2 ) × 10 ⁻⁶ / K is used as the first frit glass for the seal part A, niobium, tantalum, or Kovar metal that is a joined part The difference between the linear expansion coefficients is larger than that of any of the metal and the alumina closure body, and the seal portion A is cracked during production. However, unlike the seal part B, since one of the objects to be joined is a metal, the allowable range is wider than the seal part B due to metal malleability, and it should be in the range of ( 7 ± 2 ) × 10 ⁻⁶ / K. That's fine.

Usually, the flash discharge lamp is turned on by pulse lighting in which a large current flows instantaneously. For example, an instantaneous current of about 1500 A flows. Therefore, the temperature rise in the electrode member 5, which is a conductor in the seal portion A, is much higher than that in the seal portion B. Specifically, it was found that the temperature rose to about 400 ° C. Therefore, it is estimated that the first frit glass 6 in contact with the electrode member 5 also instantaneously rises to this temperature. Therefore, when a frit glass having a glass transition point lower than 400 ° C. is used for the seal as the first frit glass 6 in the seal portion A, the seal portion A is damaged. Therefore, the first frit glass in the seal portion A is Heat resistance is required. That is, in the seal portion A, it is necessary to withstand the temperature rise when the pulse is lit, and it is necessary to use frit glass having a relatively high glass transition temperature. However, when the glass transition point is 800 ° C. or higher, the working temperature becomes too high, which hinders actual work. Here, the glass transition point is a temperature at which the viscosity becomes ^1013.3 poise, and the temperature at which the strain can be released in 10 minutes.

  In addition, in the seal portion B, when zinc oxide (ZnO) is included in the frit glass component in a predetermined amount or more, the zinc oxide component is scattered at the time of sealing and adheres to the inner surface of the arc tube. Therefore, when the lamp is turned on, the generated light is absorbed by the adhering material, the temperature rises locally, and distortion due to thermal expansion of the inner surface of the arc tube occurs, resulting in fine cracks and transparency. In addition to being reduced, the arc tube may be damaged due to cracks. Therefore, in the seal part B, it is required that the composition of the frit glass does not contain zinc oxide in a predetermined amount or more. Furthermore, since sapphire used in the sapphire arc tube has crystal anisotropy and has a difference in linear expansion coefficient depending on the crystal direction, a crack is generated in the seal part B during the heating and cooling process when the seal part B is sealed. easy. Therefore, as the second frit glass, it is necessary to use a frit glass having a glass transition temperature (working temperature) as low as possible in order to reduce a difference in thermal expansion due to a temperature difference between heating and cooling at the time of sealing.

  As described above, the present invention uses a frit glass having a different component for each of the seal portion A and the seal portion B, so that the flash discharge lamp using the sapphire arc tube has a ceramic sealed portion. It is possible to provide a flash discharge lamp that does not cause a malfunction.

Next, experimental results when various frit glasses are used for the seal part A and the seal part B will be described with reference to FIGS.
FIG. 2 is a list showing types of frit glasses used for the first frit glass and the second frit glass.
FIG. 3 is a table showing the results of pass / fail when the frit glasses shown in the list of FIG. 2 are applied to the seal part A and the seal part B in various combinations.

  Looking at the pass / fail results in FIG. When the frit glass d shown in FIG. 2 is used as the first frit glass in the seal part A and the frit glass a shown in FIG. 2 is used as the second frit glass in the seal part B, In the frit glass, the glass transition point Tg = 630 ° C., so that the seal part A is not damaged, and the second frit glass does not contain zinc oxide. The above illuminance maintenance rate was obtained, and good results were obtained.

  No. 2, the frit glass c shown in FIG. 2 is used as the first frit glass for the seal portion A, and the frit glass a shown in FIG. 2 is used as the second frit glass for the seal portion B. In the frit glass, the glass transition point Tg = 450 ° C., so that the seal part A is not damaged, and the second frit glass does not contain zinc oxide. The above illuminance maintenance rate was obtained, and good results were obtained.

  No. 3, when the frit glass b shown in FIG. 2 is used as the first frit glass for the seal portion A and the frit glass a shown in FIG. 2 is used as the second frit glass for the seal portion B, In the frit glass, the glass transition point Tg = 460 ° C., so that the seal part A is not damaged, and the second frit glass does not contain zinc oxide. The above illuminance maintenance rate was obtained, and good results were obtained.

  No. 4, when the frit glass d shown in FIG. 2 is used as the first frit glass for the seal part A and the frit glass c shown in FIG. 2 is used as the second frit glass for the seal part B, In the frit glass, the glass transition point Tg = 630 ° C., so that the seal part A did not break, but the second frit glass contained 20% zinc oxide, so it was turned on 60,000 times. At that time, the illuminance maintenance rate decreased to 70%, but almost good results were obtained.

  No. 5, when the frit glass e shown in FIG. 2 is used as the first frit glass for the seal portion A and the frit glass c shown in FIG. 2 is used as the second frit glass for the seal portion B, In the frit glass, the glass transition point Tg = 490 ° C., so that the seal part A was not damaged, but the second frit glass contained 20% of zinc oxide, so it was turned on 60,000 times. At that time, the illuminance maintenance rate decreased to 70%, but almost good results were obtained.

  No. 6, when the frit glass a shown in FIG. 2 is used as the first frit glass for the seal part A and the frit glass f shown in FIG. 2 is used as the second frit glass for the seal part B, In the frit glass, the glass transition point Tg = 300 ° C., and therefore, the seal portion A was broken at the time of lighting 500 times, and a good result was not obtained.

  No. 7, the frit glass f shown in FIG. 2 is used as the first frit glass for the seal portion A, and the frit glass a shown in FIG. 2 is used as the second frit glass for the seal portion B. The frit glass had a glass transition point Tg = 280 ° C. Therefore, the seal part A was broken when it was turned on 500 times, and good results were not obtained.

  No. 8, when the frit glass d shown in FIG. 2 is used as the first frit glass for the seal portion A and the frit glass b shown in FIG. 2 is used as the second frit glass for the seal portion B, The frit glass had a glass transition point Tg of 630 ° C., so that no damage occurred in the seal portion A. However, since the second frit glass contained 50% zinc oxide, the illuminance maintenance rate decreased to 70% when the lamp was turned on 2000 times, and good results were not obtained.

  No. 9, the frit glass c shown in FIG. 2 is used as the first frit glass for the seal part A, and the frit glass b shown in FIG. 2 is used as the second frit glass for the seal part B. The frit glass had a glass transition point Tg = 450 ° C., and therefore, no damage occurred in the seal portion A. However, since the second frit glass contained 50% zinc oxide, the illuminance maintenance rate decreased to 70% when the lamp was turned on 2000 times, and good results were not obtained.

No. 10, when the frit glass d shown in FIG. 2 is used as the first frit glass for the seal portion A and the frit glass e shown in FIG. 2 is used as the second frit glass for the seal portion B, The frit glass had a glass transition point Tg of 630 ° C., so that no damage occurred in the seal portion A. However, the linear expansion coefficient of the second frit glass is as low as 5.4 × 10 ⁻⁶ / K compared to ( 7 ± 1 ) × 10 ⁻⁶ / K, and the sapphire arc tube that is the bonded object, and the blockage The difference in linear expansion coefficient was larger than that of the member, and the seal part B was cracked during production, and good results were not obtained.

Next, the manufacturing process of the seal part A and the seal part B of the flash discharge lamp will be described with reference to FIG.
In the figure, 9 is a frit glass ring of the first frit glass, and 10 is a frit glass ring of the second frit glass. Other configurations correspond to the same reference numerals shown in FIG.

  First, in FIG. 4A, a frit glass ring 9 is placed on the closing member 3 with the electrode 4 facing down and the electrode member 5 penetrating the closing member 3. Next, when the frit glass ring 9 is melted by heating, the frit glass ring 9 is melted and the gap between the closing member 3 and the electrode member 5 is sealed as shown in FIG. The seal part A is formed. Next, as shown in FIG.4 (c), the frit glass ring 10 is mounted on the edge part of the arc tube 2 made from sapphire, and also the assembly obtained by FIG.4 (b) is mounted on it. Next, when the frit glass ring 10 is melted at a temperature lower than the previous heating temperature, the frit glass ring 10 is melted to seal between the sapphire arc tube 2 and the closing member 3 as shown in FIG. Thus, a seal portion B made of the second frit glass 7 is formed.

1 is a cross-sectional view of a flash discharge lamp according to the present invention. It is a table | surface which shows the kind of frit glass used for 1st frit glass and 2nd frit glass. It is a table | surface which shows the result of the quality when various combinations of the frit glass shown by the list | wrist of FIG. 2 are applied to the seal part A and the seal part B. It is a figure which shows the manufacturing process of the seal part A and the seal part B of a flash discharge lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flash discharge lamp 2 Sapphire arc tube 3 Closing member 4 Electrode 5 Electrode member 6 1st frit glass 7 2nd frit glass 8 Lead wire 9 Frit glass ring 10 of 1st frit glass 2nd frit glass frit Glass ring A Seal part B Seal part

Claims (2)

In a flash discharge lamp in which both end openings of a sapphire arc tube are hermetically sealed by an alumina closing member in which an electrode member made of niobium, tantalum, or Kovar alloy is hermetically penetrated and held.
A first frit glass is used to hermetically seal between the electrode member and the closing member, and a second frit glass is used to hermetically seal between the closing member and the sapphire arc tube. frit glass is used, the first frit glass is the glass transition point of 450 to 800 ° C., the second frit glass Ri glass transition der lower than the glass transition point of the first frit glass ,
The first frit glass has a linear expansion coefficient at 300 ° C. of (7 ± 2) × 10 ⁻⁶ / K, and the second frit glass has a linear expansion coefficient of (7 ± 1) × 10 ⁻⁶ / K. A flash discharge lamp characterized by being K. Before Stories second frit glass, flash discharge lamp of claim 1, wherein the content of zinc oxide is 20% or less.

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