JP2005071898A - Flash lamp light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel structure of a flash lamp light emitting device which heats silicon wafers, etc. and does not generate white turbidity in an arc tube of a flash lamp. <P>SOLUTION: The flash lamp light emitting device, which is composed of the flash lamp 10 and a power feeding device 20 to control light emission of the flash lamp 10, is provided with a plurality of trigger electrodes 14a, 14b to feed a high voltage to the outer surface of the arc tube 11 of the flash lamp 10. By feeding a high voltage selectively to one or more trigger electrodes out of the plurality of trigger electrodes 14a, 14b every light emission of one or a plurality of times of the flash lamp 10, the flash lamp is made to emit light. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a flash lamp light emitting device, and more particularly to a flash lamp light emitting device that rapidly heats a substrate such as a silicon wafer by irradiating light.

  Conventionally, a heating apparatus for heating a substrate such as a silicon wafer by light irradiation is known. This is a method for rapidly heating, maintaining a high temperature, and rapidly cooling a wafer in a semiconductor manufacturing process, and is used in a wide range such as film formation (forming an oxide film on the wafer surface) and diffusion (diffusing impurities inside the wafer). ing. Speaking of diffusion, boron or arsenic ions are implanted into the silicon crystal in the surface layer portion of the silicon wafer, and the silicon wafer in this state is subjected to heat treatment at, for example, 1000 ° C. to diffuse the impurities. .

  As an apparatus for heat-treating a silicon wafer, a lamp is used as a heating source, and RTP (which can be rapidly heated and then rapidly cooled by irradiating the wafer with light emitted from the heating source). A Rapid Thermal Process device is known. Conventionally, a halogen lamp has been used as a heating source for this apparatus.

  However, in recent years, there has been an increasing demand for higher integration and miniaturization of semiconductor integrated circuits. For example, it is necessary to form impurity diffusion at a shallower level of 20 nm or less. Although it is possible to process at a depth of 25 to 30 nm with the apparatus described above, it is difficult to sufficiently cope with the above depth.

  As a method for achieving impurity diffusion in a very shallow region, laser irradiation (XeCL) is known. This is a method of scanning a silicon wafer with laser light having an irradiation width of several millimeters. However, an apparatus using laser light is very expensive, and heat treatment is performed while scanning the surface of the silicon wafer with a laser beam having a small spot diameter, which causes a problem in terms of throughput.

  In view of this, a method of heating a silicon wafer in a very short time by using a flash lamp as a heating source has been proposed. The heating method using a flash lamp has a great advantage because it can lower the temperature received by the silicon wafer and the irradiation time is extremely short.

As a conventional flash lamp, for example, one disclosed in Japanese Patent Application Laid-Open No. 2001-185088 is known.
JP 2001-185088 A

  By the way, in the flash lamp light emitting device using the flash lamp, the surface of the arc tube turns white as the lighting time elapses, and accordingly, the illuminance of the processed object of the emitted light also decreases, or There was a problem of non-uniformity.

  In view of the above problems, an object of the present invention is to provide a flash lamp light emitting device that heats a silicon wafer or the like and that does not cause white turbidity in the light emitting tube of the flash lamp.

The present invention employs the following means in order to solve the above problems.
The first means is a flash lamp light emitting device comprising a flash lamp and a power feeding device for controlling the light emission of the flash lamp, and a plurality of trigger electrodes for supplying a high voltage to the outer surface of the light emitting tube of the flash lamp. The flash lamp is made to emit light by selecting one or a plurality of trigger electrodes from the plurality of trigger electrodes and supplying a high voltage every one or a plurality of times of light emission of the flash lamp. It is characterized by that.

  The second means is a flash lamp light emitting device comprising a flash lamp and a power feeding device for controlling the light emission of the flash lamp, and a plurality of trigger electrodes for supplying a high voltage to the outer surface of the light emitting tube of the flash lamp. Providing a high voltage alternately to one or a plurality of trigger electrodes and the remaining one or a plurality of trigger electrodes among the plurality of trigger electrodes every one or a plurality of times of light emission of the flash lamp. The flash lamp is made to emit light.

  A third means is characterized in that, in the first means or the second means, the trigger electrode is provided in close contact with the outer surface of the arc tube by printing or vapor deposition.

  A fourth means is characterized in that, in the third means, the printing or vapor deposition is performed on an outer surface of the arc tube coated with a ceramic oxide layer.

  A fifth means is characterized in that, in any one of the first to fourth means, the trigger electrode is covered with a high melting point oxide.

  A sixth means is characterized in that, in the fifth means, the refractory oxide is alumina or yttria.

  A seventh means is characterized in that, in the first means or the second means, the trigger electrode has a linear conductor disposed in a pipe made of a dielectric material.

According to an eighth means, in any one of the first to seventh means, the arc tube is made of a material mainly composed of aluminum oxide (Al ₂ O ₃ ), and the trigger electrode is It is made of a material mainly composed of tungsten or molybdenum.

  According to a ninth means, in any one of the first to eighth means, a plurality of the flash lamps are arranged side by side, and the trigger electrode is shared by adjacent flash lamps. It is arranged.

  According to the first aspect of the present invention, in the flash lamp light emitting device including the flash lamp and a power feeding device that controls light emission of the flash lamp, a plurality of lamps that supply a high voltage to the outer surface of the arc tube of the flash lamp. A plurality of trigger electrodes, and each time the flash lamp emits light one or more times, the flash lamp is selected by supplying one or more trigger electrodes from the plurality of trigger electrodes and supplying a high voltage. Since the light is emitted, each time the flash lamp emits light, the trigger electrode is selected and a high voltage is supplied, so the plasma generation position is not fixed at a fixed position in the discharge vessel, and the discharge vessel becomes clouded. Can be prevented.

  According to the second aspect of the present invention, in the flash lamp light emitting device including the flash lamp and a power feeding device that controls the light emission of the flash lamp, a plurality of lamps that supply a high voltage to the outer surface of the light emitting tube of the flash lamp. A plurality of trigger electrodes are provided, and each time the flash lamp emits light one or more times, one or more trigger electrodes of the plurality of trigger electrodes and the remaining one or more trigger electrodes are alternately switched to a high voltage. Since the flash lamp is caused to emit light by supplying a high voltage, the trigger electrode is alternately supplied every time the flash lamp emits light, so that the plasma generation position is fixed at a fixed position in the discharge vessel. It is not possible to prevent the discharge vessel from becoming clouded.

  According to the invention described in claim 3, since the trigger electrode is provided in close contact with the outer surface of the arc tube by printing or vapor deposition, the position of the trigger electrode does not change as the flash lamp emits light. A high voltage can be reliably applied to the discharge vessel, and a trigger electrode having a small width or height can be accurately applied, so that the number of trigger electrodes can be easily increased.

  According to the invention described in claim 4, since the printing or vapor deposition is performed on the outer surface of the arc tube coated with the ceramic oxide layer, even if the outer surface of the discharge vessel is uneven, The print printing or vapor deposition can be performed reliably.

  According to the invention described in claim 5, since the trigger electrode is coated with the high melting point oxide, it is possible to prevent disconnection due to oxidation of the trigger electrode or sliding due to contact.

  According to the sixth aspect of the present invention, alumina or yttria is used as the high melting point oxide, so that glass or crystalline thin film using vacuum deposition, sputtering deposition or sol-gel method can be easily formed. Can do.

  According to the seventh aspect of the present invention, since the linear conductor is arranged in the pipe made of the dielectric material, the trigger electrode has a discharge vessel even when the constituent material of the linear conductor is scattered by sputtering. Can be prevented from adhering to and contaminating the outer surface of the material or falling onto the surface of the irradiated object.

According to the invention described in claim 8, since the arc tube is composed of a material mainly composed of aluminum oxide (Al ₂ O ₃ ), and the trigger electrode is composed of a material mainly composed of tungsten or molybdenum, It is possible to most effectively prevent white turbidity of the arc tube.

  According to the ninth aspect of the present invention, a plurality of flash lamps are arranged side by side, and the trigger electrode is arranged so as to be shared with adjacent flash lamps, so that the number of trigger electrodes used can be suppressed. It is possible to prevent the trigger electrode from being worn. Furthermore, the trigger circuit can be reduced in size.

An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a diagram showing a schematic configuration of a flash lamp light emitting device according to the present invention.
In the figure, a straight tube type quartz glass discharge vessel 11 of a flash lamp 10 is filled with, for example, xenon gas, and both ends are sealed to define a discharge space inside. A pair of electrodes, an anode 12 and a cathode 13, are disposed opposite to each other in the discharge space, and two linear trigger electrodes 14 a and 14 b are disposed along the longitudinal direction on the outer surface of the discharge vessel 11. The trigger electrodes 14 a and 14 b are held by a trigger band 15.

As an example, the flash lamp 10 has an inner diameter of the discharge vessel 11 selected from a range of φ6 to φ15 mm, for example, φ10 mm, and a length of the discharge vessel 11 is selected from a range of 200 to 550 mm, for example, 300 mm.
The amount of sealed xenon gas is selected from the range of 200 to 1500 torr, for example, 500 torr. Further, the main sealed gas is not limited to xenon gas, and argon or krypton gas may be employed. It is also possible to add other substances such as mercury in addition to xenon gas.
For the discharge vessel 11, quartz glass, alumina, sapphire, YAG, yttria, or the like is used.
The electrodes 12 and 13 are sintered electrodes mainly composed of tungsten, and the size is selected from the range of 4 to 10 mm in outer diameter, for example, 5 mm, and the length is selected from the range of 5 to 9 mm. For example, 7 mm. The distance between the electrodes is selected from a range of 160 to 500 mm, for example, 280 mm. Further, barium oxide (BaO), calcium oxide (CaO), strontium oxide (SrO), alumina (Al ₂ O ₃ ) and the like are mixed in the cathode 13 as an emitter.

  The trigger electrodes 14a and 14b are disposed over the entire length of the flash lamp 10, and the trigger band 15 needs to electrically insulate a plurality of trigger electrodes, so that Teflon (registered trademark), polychlorinated chloride is required. An insulator such as vinyl is used.

  The power feeding device 20 includes a light emitting circuit 21 and a trigger circuit 22. The light emitting circuit 20 is electrically connected to the anode 11 and the cathode 12, and the trigger circuit 21 is connected to trigger electrodes 14a and 14b. The light emitting circuit 21 and the trigger circuit 22 transmit / receive signals to / from each other. When the main capacitor in the light emitting circuit 21 is fully charged to be discharged as described later, the signal is transmitted to the trigger circuit 22 and the trigger circuit 22 is transmitted. Therefore, a high voltage is applied to the trigger electrode 14 so that the flash lamp 10 emits light.

Each of the trigger electrodes 14a and 14b is configured to be able to receive a signal from the trigger circuit 22 independently. The trigger electrode 14a or the trigger electrode 14b selected by the trigger circuit 22 is used to switch the lamp. The light is emitted.
The light emission interval of the flash lamp 10 is, for example, one light emission per minute. In this case, a high voltage is applied to each trigger electrode 14a, 14b every two minutes. The high voltage applied to each trigger electrode 14a, 14b is, for example, −15 KV.

2A is a cross-sectional view of the discharge vessel showing a state in the discharge vessel 11 when a high voltage is applied to the trigger electrode 14a, and FIG. 2B is a view when a high voltage is applied to the trigger electrode 14b. 2 is a cross-sectional view of a discharge vessel showing a state in the discharge vessel 11. FIG.
As shown in these figures, the trigger electrodes 14a and 14b are arranged almost symmetrically at two locations on the outer surface of the discharge vessel 11, and first, as shown in FIG. 2A, a high voltage is applied to the trigger electrode 14a. When (15 KV) is applied, plasma P1 is generated in a region near the trigger electrode 14a of the discharge vessel 11, and the flash lamp 10 emits light. Next, as shown in FIG. 2B, when a high voltage is applied to the trigger electrode 14b, plasma P2 is generated in a region near the trigger electrode 14b of the discharge vessel 11, and the flash lamp 10 emits light. Similarly, the flash lamp 10 is caused to emit light by sequentially changing the trigger electrode for each light emission.

  Here, to explain the cause of white turbidity on the inner surface of the conventional discharge vessel, the conventionally known flash lamp has a structure in which one trigger electrode is arranged at any position on the outer surface of the discharge vessel. Plasma is always generated near the trigger electrode in the discharge vessel, and flash emission occurs. For this reason, it is presumed that white turbidity is caused on the inner surface of the discharge vessel, causing a decrease in the amount of emitted light and a variation in positional emitted light. Further, as the white turbidity progresses, the material constituting the discharge vessel, for example, quartz glass, becomes a fine powder and falls into the discharge vessel and does not accumulate. It will be further encouraged. Furthermore, the plasma may be distorted with respect to the constituent materials of the discharge vessel.

  On the other hand, in the flash lamp light emitting device of the present invention, since the plurality of trigger electrodes 14a and 14b are used alternately and regularly with good balance, the plasma generation position is fixed at a fixed position in the discharge vessel. There is nothing. Therefore, white turbidity at a specific position of the discharge vessel can be prevented.

Here, a phenomenon in the discharge vessel 11 when a plurality of trigger electrodes 14a and 14b are alternately used will be described. First, in the first light emission, plasma P1 is generated in a region near the activated trigger electrode (for example, 14a) in the discharge vessel 11, and the surface of the inner wall of the arc tube adjacent to the plasma P1 is caused by heat conduction and light. It is heated up to melt. Therefore, evaporation of a composition of silica (SiO _x (0 <x <2)) occurs in the discharge vessel 11. Furthermore, the arc tube is distorted by the action of strong ultraviolet light (so-called UV distortion). On the other hand, the evaporated silica comes and accumulates on the inner wall of the arc tube opposite to the activated trigger electrode 14a, causing white discoloration.
Next, when the other trigger electrode (for example, 14b) is operated, plasma P2 is generated in a region close to the trigger electrode 14b. However, silica that has come first is deposited on the inner wall of the arc tube adjacent to the trigger electrode 14b. The arc tube is exposed to the plasma through silica. Accordingly, the inner wall of the arc tube adjacent to the trigger electrode 14b is heated in the same manner as in the case of the first light emission, but it is the silica portion deposited earlier that evaporates, and the inner wall surface of the arc tube hardly evaporates. Further, since silica absorbs ultraviolet light, almost no UV distortion is induced, and the mechanical strength of the arc tube hardly decreases.

  In short, in the repeated light emission cycle, the silica scattered by the first light emission is heated by the heat and light from the plasma and continues to move in the arc tube, so the progress of whitening of the arc tube is suppressed, and UV Generation or accumulation of distortion is prevented.

  In particular, a flash lamp used for rapid heating of an object to be processed such as a semiconductor wafer or a liquid crystal substrate has a large emission energy of 6000 J, and the temperature of the object to be processed is instantaneously increased to 1500 ° C. When the energy load and the thermal load on such a flash lamp are extremely severe and severe, the above-described method of supplying a high voltage to the trigger electrode functions extremely effectively. In other words, the flash lamp itself has been widely used for camera strobes, printer fixing light sources, etc., but in such applications with low emission energy, the cloudiness of the discharge vessel never occurs. It is not necessary to adopt such a high voltage supply method to the trigger electrode.

The trigger electrodes 14a and 14b have been described here as being switched for each flash emission. However, the present invention is not limited to this mode, and the same trigger electrode is used for flash emission several times. Is also possible. For example, the flash emission may be performed 100 times continuously using the trigger electrode 14a, and then the flash emission may be continuously performed 100 times using the trigger electrode 14b. In addition, the trigger electrode may be driven regularly or randomly.
Further, the number of trigger electrodes is not limited to two, and a large number may be provided. In this case, a large number of trigger electrodes may be caused to emit light one by one, or a plurality of trigger electrodes may be grouped to emit light in group units. For example, when four trigger electrodes are arranged, any two trigger electrodes may be used as one group and the remaining two trigger electrodes as another group, and these may be used for each group. Good.

  As described above, the flash lamp light emitting device of the present invention has a plurality of trigger electrodes arranged on the outer surface of the discharge vessel of the flash lamp. In this case, it is possible to prevent the flash emission that is offset in the case, and thus it is possible to solve problems such as cloudiness of the discharge vessel.

Note that the present inventors have the most effective white turbidity prevention effect when the constituent material of the discharge vessel 11 is alumina (Al ₂ O ₃ ) and a material mainly composed of tungsten is deposited as a trigger electrode. It was confirmed that it was excellent.

  FIGS. 3A to 3C are cross-sectional views of a discharge vessel having a trigger electrode structure different from the trigger electrode structure shown in FIG.

  FIG. 3A is a cross-sectional view of a discharge vessel in which trigger electrodes 14a to 14h are arranged in a balanced manner at eight positions on the outer surface of the discharge vessel 11, and these trigger electrodes 14a to 14h are formed on the discharge vessel 11. It is formed on the outer surface by printing or vapor deposition.

  The advantage of this trigger electrode structure is that the positions of the trigger electrodes 14a to 14h do not change as the flash lamp 10 emits light because the trigger electrodes 14a to 14h are fixed in close contact with the outer surface of the discharge vessel 11. That is, in the case of a linear conductor, the trigger electrode itself may expand or contract due to the high temperature during light emission, or may be partially separated from the discharge vessel due to vibration or the like. For this reason, application of a high voltage to the discharge vessel of the trigger electrode becomes insufficient, or the position is uneven. In particular, in the heating of semiconductor wafers and liquid crystal substrates, the discharge vessel at the time of lamp emission is about 100 ° C., whereas the linear trigger electrode has a high temperature of several hundred degrees C. Is remarkable.

  The advantage of printing or vapor deposition is that when the trigger electrodes 14a to 14h are formed, an electrode having a small width or height can be accurately applied, and the number of trigger electrodes can be easily increased as shown in the figure. .

The materials of the trigger electrodes 14a to 14h are, for example, tungsten, nickel, aluminum, platinum, silver, palladium, rhodium, inconel (nickel-chromium-iron alloy), molybdenum gold, molybdenum silicide, gold alloy, and the like. The width and thickness of 14h can be made at a level of several hundred μm.
Furthermore, the flash lamp 10 may be arranged at intervals of about several millimeters, specifically about 2 mm. In the case of such a flash lamp arrangement structure, the height of the trigger electrodes 14a to 14h is increased. Is low.

  Further, in order to improve the adhesion of the trigger electrodes 14a to 14h to the discharge vessel 11, a high melting point ceramic oxide is applied to the discharge vessel 11 to form the trigger electrodes 14a to 14h thereon. Thereby, even when the outer surface of the discharge vessel is uneven, the trigger electrode can be easily applied.

FIG. 3B is a cross-sectional view of the discharge vessel in which the trigger electrodes 14a to 14h whose outer surfaces are coated with high melting point oxides are arranged at equal intervals on the outer surface 8 of the discharge vessel 11 in a balanced manner. 14a to 14h are formed on the outer surface of the discharge vessel 11 by printing or vapor deposition.
As the refractory oxide film material, alumina or yttria is used, whereby a glass or crystalline thin film using vacuum deposition, sputtering deposition or sol-gel method can be formed.
By configuring the trigger electrodes 14a to 14h in this manner, disconnection due to oxidation of the trigger electrode or sliding due to contact can be prevented.

FIG. 3C is a cross-sectional view of the discharge vessel in which the trigger electrodes 14a to 14c are arranged at three locations on the outer surface of the discharge vessel 11, and the trigger electrodes 14a to 14c are on the side (lower side in the drawing) where the irradiated object is arranged. The trigger electrodes 14a to 14c have a structure in which a linear conductor 142 is arranged in a pipe tube 141 made of a dielectric material such as quartz glass.
By configuring the trigger electrodes 14a to 14c in this way, when the constituent material of the linear conductor 142 is scattered by sputtering, it adheres to the outer surface of the discharge vessel 11 and becomes dirty, or on the surface of the irradiated object. It can be prevented from falling. In order to prevent the trigger electrodes 14a to 14c from being oxidized, an inert gas such as nitrogen or argon can be enclosed in the pipe pipe 141.

  The reason why the trigger electrodes 14a to 14c are not disposed on the outer surface of the discharge vessel 11 on the side where the irradiated object is disposed is to prevent light shielding against the irradiated object, and also the cloudiness caused by the occurrence of the plasma being offset. If the generation is at a level that does not have a practical influence, it is possible to dispose the trigger electrode at a specific position.

Here, as the linear conductor of the trigger electrode shown in FIGS. 2 and 3A, for example, tungsten, nickel, aluminum, platinum, inconel (nickel-chromium-iron alloy), molybdenum, or the like is used. The outer diameter is selected from, for example, a range of φ0.5 to 3.0 mm, and for example, a φ1.0 mm is adopted.
Further, the structure, number, and arrangement of the trigger electrodes are not limited to the structures shown in FIG. 2 and FIGS. 3A to 3C, and other forms are also possible as appropriate. For example, eight trigger electrodes having the structure shown in FIG. 3C are disposed as shown in FIG. 3A, or FIG. 2 and FIG.
It is also possible to use a combination of trigger electrodes having the structure shown in (c).
Further, the trigger electrode shown in FIG. 2 and FIGS. 3A to 3C is not limited to a linear shape. For example, the trigger electrode can be spirally wound around the discharge vessel. A plurality of insulated spiral electrodes are alternately wound around the discharge vessel.

FIG. 4 is a diagram illustrating a specific configuration of the light emitting circuit 21 and the trigger circuit 22 of the power feeding device 20 illustrated in FIG. 1.
As shown in the figure, the light emitting circuit 21 is connected to an AC power source AC, and a switching inverter circuit, a transformer T, a rectifier circuit, a control circuit for the inverter circuit, and a backflow prevention diode D on the secondary side of the rectifier circuit. , Resistor R, main capacitor C, and coil L.
The resistor R detects the charging voltage of the main capacitor C, and the signal is transmitted to the control circuit.
The flash lamp 10 is provided with trigger electrodes 14 a and 14 b, and each trigger electrode 14 a and 14 b is connected to a trigger circuit 22.

In the light emitting circuit 21, energy is charged in the main capacitor C through a switching inverter circuit, a rectifier circuit, and the like. When the main capacitor C is charged with sufficient energy, a detection value from the resistor R is transmitted to the control circuit, and a command from the control circuit is transmitted to the trigger circuit 22. When receiving the command, the trigger circuit 22 drives the trigger electrode 14. As a result, a high voltage is generated at the trigger electrode 14 to induce an electric field using the discharge vessel 10 as a dielectric, and at the same time, the energy of the main capacitor C is instantaneously discharged and flash emission (flash emission) occurs.
Here, the trigger circuit 22 has a selection function for determining which one of the plurality of trigger electrodes 14a and 14b is used, and generates a high voltage for the selected trigger electrode. .

With regard to the light emission of the flash lamp 10 in the power supply device 20, for example, charging / discharging of the main capacitor C is repeated, for example, 0.5 to 2 times per minute, specifically at a rate of 1 time. The capacitor C is selected from, for example, a range of 2000 to 5000 V, for example, 4500 V, and is selected from a range of 1200 to 7500 J in terms of energy. For example, energy of 6000 J is charged and discharged and supplied to the flash lamp.
For example, a high voltage of −5 to −15 KV is applied to the trigger electrode. Incidentally, the application of a minus high voltage to the trigger electrode causes plasma to be generated in a region near the trigger electrode in the discharge vessel 11.
Normally, a plurality of flash lamps as shown in FIG. 1 are arranged side by side as the flash lamp 10. Specifically, the flash lamp 10 is selected from 5 to 30, for example, ten. Further, the light intensity on the irradiated surface, the range number of 5-30 flash lamp 10, is selected from 10~50J / cm ² range, for example, a 20 J / cm ^2.

FIG. 5 is a diagram showing a schematic configuration of a light heating device using the flash lamp light emitting device according to the present invention.
As shown in the figure, the light heating device includes a flash lamp light emitting device 30 and a heating device main body 50.

The flash lamp 10 is housed in the casing 41 together with the reflecting mirror 42, and a plurality of, for example, five flash lamps 10 are arranged, but in reality, about 30 flash lamps 10 are 2 to 3 mm. Are arranged side by side in the gap. For example, three trigger electrodes 14 are provided for each flash lamp 10. Note that a translucent glass may be disposed on the front surface of the casing 41 to partition the chamber 51 described later.
The chamber 51 is made of quartz glass having an atmospheric gas inlet 51A and an outlet 51B, and includes a stage 52 on which a silicon wafer W as an example of an object to be processed is placed. A quartz flat plate 54 is provided as an airtight light-transmitting member on the ceiling surface (illustrated upper surface) of the chamber 51. A heater lamp 53 is embedded in the stage 52, and the temperature of the heater lamp 53 is controlled by a chamber control circuit 55. The chamber control circuit 55 also performs an elevating function of the stage 52, opening / closing control of the gas inlet 51A and the gas outlet 51B, and the like.
Other configurations correspond to the configurations of the same reference numerals shown in FIG.

When the silicon wafer W into which impurities are implanted is carried into the chamber 51 of the heating apparatus main body 50, the silicon wafer W is preheated to a predetermined temperature by the heater lamp 53 so that thermal diffusion of impurities does not become a problem. Thereafter, the flash lamp 10 is caused to emit light, and the silicon wafer W is subjected to heat treatment by flash radiation.
By this heat treatment, the surface portion of the silicon wafer W within 20 nm is rapidly heated to a high temperature and then rapidly cooled. The preheating is preferably performed for the purpose of reducing the temperature gradient in the thickness direction of the wafer and minimizing the energy injected into the lamp necessary for raising the temperature of the irradiated surface to a necessary level. The heating temperature is selected from the range of 300 to 500 ° C, and is, for example, 350 ° C.
Further, the surface temperature of the wafer during the heat treatment by the heater lamp 53 and the flash lamp 10 is 1000 ° C. or more, and specifically, the heat treatment is performed in the range of 1000 ° C. to 1300 ° C. Thus, by heating the maximum temperature of the wafer to 1000 ° C. or higher, the impurity diffusion layer can be reliably formed on the surface layer portion of the wafer.

  In this flash lamp light emitting device 30, three trigger electrodes 14 are arranged for each flash lamp 10. However, as described later, when trigger electrodes are arranged between adjacent flash lamps 10, they are adjacent to each other. The trigger electrode to be used can be shared for both flash lamps.

FIG. 6 is a diagram showing a configuration in which a trigger electrode disposed between adjacent flash lamps is shared by adjacent flash lamps.
As shown in the figure, here, for convenience, four flash lamps 10 a to 10 d and five trigger electrodes 14 a to 14 e are arranged in a reflection mirror 42.
These trigger electrodes 14a to 14e are the same as those shown in FIG. 3C, and a linear conductor made of, for example, molybdenum is disposed in a quartz glass tube.

In such a configuration, when a high voltage is applied to the trigger electrodes 14b and 14d among the five trigger electrodes 14a to 14e, all the flash lamps 10a to 10d can emit light simultaneously. At the time of the next light emission, if a high voltage is applied to the trigger electrodes 14a, 14c, 14e among the five trigger electrodes 14a-14e, all the flash lamps 10a-10d can be made to emit light at the same time.
When the flash lamps are arranged close to each other as described above and a high voltage is applied to the trigger electrode, two adjacent flash lamps can be caused to emit light by one trigger electrode.

  By configuring the trigger electrode in this way, the number of trigger electrodes used can be reduced, and wear of the trigger electrodes can be prevented. In addition, the trigger circuit can be reduced in size. Furthermore, as a matter of course, the occurrence of white turbidity in the discharge vessel can be satisfactorily prevented by selecting the trigger electrodes alternately and regularly.

FIG. 7 shows the spectrum of the radiation emitted to the silicon wafer W shown in FIG. The vertical axis indicates the relative radiation intensity with respect to the intensity at a wavelength of 500 nm, and the horizontal axis indicates the wavelength (nm).
Among these, if the wavelength 220 nm to wavelength 370 nm is short wavelength light and the wavelength 370 to 800 nm is long wavelength light, the short wavelength light and the long wavelength light have different absorption amounts in the thickness direction of the silicon wafer.
Specifically, light with a wavelength of 220 nm to 370 nm heats only a very shallow portion of the surface with high light intensity, whereas light with a wavelength of 370 to 800 nm has the same degree (short) from the surface to a region of depth of 400 nm. Contributes to heating with a light intensity of (compared to wavelength).
Here, the thickness of the silicon wafer is approximately 725 μm, and in order to activate impurities introduced by ion implantation or the like, it is necessary to heat up to a depth of about 100 nm including the surface layer portion 10 nm.

Next, an experiment for verifying the effect of the flash lamp light emitting device of the present invention will be described.
FIG. 8 is a diagram showing experimental results of the conventional example, Invention 1 and Invention 2, wherein the vertical axis indicates relative illuminance and the horizontal axis indicates the number of times of light emission.
In the figure, the conventional example is a case where only one linear conductor made of molybdenum is arranged on the outer surface of the discharge vessel of the flash lamp. Inventions 1 and 2 are shown in FIG. 3B on the outer surface of the discharge vessel of the flash lamp. A trigger electrode having a structure shown in FIG. 2 is used, and a molybdenum material is printed and coated with a high melting point oxide. The difference between Invention 1 and Invention 2 is that the invention 1 is a lighting system in which eight trigger electrodes are provided on the outer surface of the discharge vessel of one flash lamp, and three trigger electrodes are selected and lighted for each flash emission. On the other hand, in the invention 2, eight trigger electrodes are provided on the outer surface of the discharge vessel of one flash lamp, and three trigger electrodes are selected for each flash emission, and the flash emission is performed. This is a lighting method in which light is emitted by an electrode.
The flash lamp used in the experiment is the same except for the structure related to the trigger electrode and the lighting method described above. The distance between the electrodes is 300 mm, the inner diameter is 10 mm, the input energy is 900 J, and the discharge time width is 200 μsec. It is.

The illuminance is measured by providing a pinhole of φ5 mm at a position 50 mm away from the flash lamp, and measuring with an instantaneous spectroscope (spectral radiometer) through an optical fiber with a wavelength resolution of 0.5 nm and a time resolution of 5 ms. The light emission intensity at 800 nm was determined.
In this illuminance measurement, the illuminance at the first flash emission, the 1000th flash emission, the 5000th flash emission, and the 10000th flash emission was measured for each of the conventional example, Invention 1 and Invention 2.
As shown in the figure, in the conventional flash lamp, when the initial illuminance is 1, it is 0.9 for 1000 flashes, 0.5 for 5000 flashes, and 0.4 for 10000 flashes. did.
On the other hand, in the flash lamp of the present invention, it was confirmed that the invention 1 and the invention 2 both maintain a relative illuminance value of about 0.9 even after 1000 times of light emission and 0.9 and 10,000 times of light emission. .
In addition, when looking at the discharge vessel after emitting light 10,000 times, the flash lamp of the conventional example was intensely clouded on the inner surface, whereas each flash lamp of Invention 1 and Invention 2 was visually observed. The cloudiness that could be formed was not formed.

  As described above, the flash lamp light emitting device according to the present invention can select a plurality of trigger electrodes alternately and regularly, so that the discharge vessel can be used even under severe conditions. It became clear that cloudiness was prevented well.

It is a figure which shows schematic structure of the flash lamp light-emitting device based on this invention. It is sectional drawing of the discharge container which shows the state in the discharge container 11 when a high voltage is applied to trigger electrode 14a, 14b. It is sectional drawing of the discharge vessel which has a trigger electrode structure different from the trigger electrode structure shown in FIG. FIG. 2 is a diagram illustrating a specific configuration of a light emitting circuit 21 and a trigger circuit 22 of the power feeding device 20 illustrated in FIG. 1. It is a figure which shows schematic structure of the optical heating apparatus using the flash lamp light-emitting device based on this invention. It is a figure which shows the structure which shared the trigger electrode arrange | positioned between adjacent flash lamps with respect to the adjacent flash lamp. It is a figure showing the spectrum of the emitted light irradiated to the silicon wafer W shown in FIG. It is a figure which shows the experimental result of a prior art example, invention 1 and invention 2.

Explanation of symbols

10, 10a to 10d Flash lamp 11 Quartz glass discharge vessel 12 Anode 13 Cathode 14, 14a to 14h Trigger electrode 141 Pipe tube 142 Linear conductor 15 Trigger band 20 Power feeding device 21 Light emitting circuit 22 Trigger circuit 30 Flash lamp light emitting device 41 Casing 42 reflective mirror 50 light heating device main body 51 chamber 51A atmosphere gas inlet 51B outlet 52 stage 53 heater lamp 54 quartz flat plate 55 chamber control circuit W silicon wafer

Claims (9)

In a flash lamp light emitting device composed of a flash lamp and a power feeding device that controls the light emission of the flash lamp,
Provided with a plurality of trigger electrodes for supplying a high voltage to the outer surface of the arc tube of the flash lamp,
The flash lamp is caused to emit light by selecting one or a plurality of trigger electrodes from the plurality of trigger electrodes and supplying a high voltage every one or a plurality of times of light emission of the flash lamp. A flash lamp light emitting device. In a flash lamp light emitting device composed of a flash lamp and a power feeding device that controls the light emission of the flash lamp,
Provided with a plurality of trigger electrodes for supplying a high voltage to the outer surface of the arc tube of the flash lamp,
By alternately supplying a high voltage to one or a plurality of trigger electrodes and the remaining one or a plurality of trigger electrodes among the plurality of trigger electrodes for each one or a plurality of times of light emission of the flash lamp, A flash lamp light emitting device characterized by causing a flash lamp to emit light.   The flash lamp light emitting device according to claim 1, wherein the trigger electrode is provided in close contact with the outer surface of the arc tube by printing or vapor deposition.   4. The flash lamp light emitting device according to claim 3, wherein the print printing or vapor deposition is performed on an outer surface of the arc tube coated with a ceramic oxide layer.   The flash lamp light emitting device according to any one of claims 1 to 4, wherein the trigger electrode is coated with a high melting point oxide.   6. The flash lamp light emitting device according to claim 5, wherein the high melting point oxide is alumina or yttria.   3. The flash lamp light emitting device according to claim 1, wherein the trigger electrode includes a linear conductor disposed in a pipe made of a dielectric material. 4. The arc tube is composed of a material mainly containing aluminum oxide (Al 2 _{O 3),} the trigger electrode claims 1 to, characterized in that they are composed of a material composed mainly of tungsten or molybdenum The flash lamp light emitting device according to claim 7.   9. The flash lamp according to claim 1, wherein a plurality of the flash lamps are arranged side by side, and the trigger electrode is disposed so as to be shared by adjacent flash lamps. A flash lamp light emitting device according to claim 1.

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