Filament lamp and light-irradiation-type heat treatment device

A filament lamp includes multiple filament assemblies having filaments connected to paired leads, arrayed in order within a light emitting tube and following a tube axis thereof. Each lead is electrically connected in a seal area. Each filament is powered independently. The light emitting tube includes insulating walls or inner tubes between the filaments and leads that have openings through which the leads pass, and located along the tube axis in proximity to the inner wall of the light emitting tube. Multiple lead accommodation spaces corresponding to the number of leads are provided in the light emitting tube by the insulating walls with each lead passing through an opening in the insulating wall and placed without short circuits in its lead accommodation space.

FIELD OF INVENTION

This invention concerns a filament lamp and light-irradiation-type heat treatment device, and particularly a filament lamp used for heat treatment of a workpiece and a light-irradiation-type heat treatment device equipped with such a filament lamp.

DESCRIPTION OF RELATED ART

Heat treatment is used in a variety of processes in the manufacture of semiconductors, including film growth, oxidation, nitriding, film stabilization, silicidation, crystallization, and ion injection activation. In particular, rapid thermal processing (hereafter referred to as “RTP”) of a semiconductor wafer or other workpiece to be treated by quickly raising and lowering its temperature enables improved throughput and quality, and so its use is desirable.

Incandescent lamps, for example, are used as the light source in this sort of light-irradiation-type heat treatment device (hereafter referred to as “heat treatment device”).

Incandescent lamps have filaments arranged inside light emitting tubes made of a material that is transparent to light. Incandescent lamps irradiate 90% or more of the invested power, and can heat the workpiece to be treated without making contact. It is therefore possible, when using them as heat sources for heating glass substrates or semiconductor wafers, to raise the temperature of the workpiece to be treated more quickly than by the resistance heating method, specifically, to a temperature of 1000° C. or higher in a period from several seconds to several tens of seconds, and also to cool the workpiece quickly by stopping the light irradiation.

When the workpiece to be treated is, for example, a semiconductor wafer (e.g., a silicon wafer), if there is unevenness of the temperature distribution of the semiconductor wafer when it is heated to a temperature of 1050° C. or higher a phenomenon called “slip”, in which crystal transition defects arise and quality declines, is liable to occur in the semiconductor wafer. For this reason, it becomes necessary to heat the semiconductor wafer, hold it at a high temperature, and then cool it so that the temperature distribution will be even across the entire surface. In other words, highly precise uniformity of temperature of the workpiece to be treated is sought in RTP.

Even in the event that the light irradiation is done so that the degree of irradiation is uniform for semiconductor wafers that have the same physical characteristics across the entire surface of the semiconductor wafer, the temperature of the semiconductor wafer will not be uniform. For example, the temperature at the edges of the semiconductor wafer will be lower at the edges because heat will be radiated by the side surfaces of the semiconductor wafer. As a result of this heat release, there will be a temperature distribution on the semiconductor wafer. If there is unevenness in the semiconductor wafer temperature distribution, when the semiconductor wafer is heated to 1050° C. or higher, as noted above, slip will occur in the semiconductor wafer.

Accordingly, it is desirable to compensate for the temperature drop due to heat radiation from the sides of the semiconductor wafer and thus even out the temperature distribution in the semiconductor wafer by means of light irradiation such that the surface at the edges of the semiconductor wafer is irradiated to a greater degree than the surface at the center of the semiconductor wafer.

As for conventional heat treatment device, Japanese Pre-grant Patent Report H7-37833 discloses heat treatment device that uses incandescent lamps to heat a glass substrate or semiconductor wafer.

FIG. 15is a cross section of heat treatment device200with the conventional technology described in Japanese Pre-grant Patent Report H7-37833. As shown in this Figure, this heat treatment device200is constituted such that a workpiece202to be treated is accommodated in a chamber201made of light-transparent material, with two stages of multiple incandescent lamps for heating203,204outside the chamber201, facing from above and below, and with axes that cross each other. Both surfaces of the workpiece202to be treated are heated by means of light irradiation from the incandescent lamps for heating203,204.

FIG. 16is an oblique simplified view of the heat treatment device shown inFIG. 15, including the upper and lower stages of incandescent lamps for heating203,204and the workpiece202to be treated. As shown inFIGS. 15-16, the upper and lower incandescent lamps for heating203,204are placed with their tube axes crossing and so it is possible to heat the workpiece202to be treated uniformly. Using this equipment, moreover, it is possible to prevent the reduction of temperature due to the action of heat radiation from the edges of the workpiece202to be treated. For example, the lamp output of the incandescent lamps for heating L1, L2at the ends of the stage above the workpiece202to be treated is set higher than the lamp output of the incandescent lamp for heating L3at the center. Similarly, the lamp output of the incandescent lamps for heating L4, L5at the ends of the stage below the workpiece202to be treated is set higher than the lamp output of the incandescent lamp for heating L6at the center. It is possible, by this means, to compensate for the reduction of temperature due to the action of heat radiation from the workpiece202to be treated, to minimize the temperature difference between the center and edges of the workpiece202to be treated, and thus to make the temperature distribution of the workpiece202to be treated uniform.

It has been learned, however, that the problem described below may occur in the conventional heat treatment device described above. Specifically, in the case that the workpiece202to be treated is a semiconductor wafer, for example, it is common to form a film of metallic oxide or other material on the surface of a semiconductor wafer by a sputtering method and then dope it with impurities by means of ion implantation. In this case, the film thickness of such a metallic oxide and the density of the impurity ions will have a localized distribution on the surface of the semiconductor wafer. This localized distribution will not necessarily have central symmetry with respect to the center of the semiconductor wafer. Taking the density of the impurity ions as an example, sometimes there is a difference, as shown inFIG. 16, between the density of the impurity ions in a small, special region2021that does not have central symmetry with respect to the center of the semiconductor wafer and the other region2022. Even if such a special region2021and the other region2022are irradiated to have the same irradiation intensity, there may be a difference in the speed of temperature rise between the special region2021and the other region2022, and the temperature of the special region2021and the temperature of the other region2022will not necessarily be the same.

Using the conventional heat treatment device200described above, it is relatively easy to compensate for the temperature drop at the edges of the workpiece202to be treated due to heat radiation and prevent reduction of the temperature at the edges, and to make the temperature distribution of the workpiece202to be treated uniform. Nevertheless, for a small, special region2021on the semiconductor wafer with a total length that is shorter than the light emission length of the lamp, as shown inFIG. 16, in the event of light irradiation suited to the properties of the special region2021, there will also be light irradiation of the region2022outside the special region2021. Accordingly, it is not possible to control the temperature state so that it is suited both to the special region2021and to the other region2022. That is, it is not possible to control the irradiation of the small, special region2021so that the temperature of the two regions2021and2022is uniform. Therefore, there is the problem of an undesirable temperature distribution in the treatment temperature of the workpiece202to be treated, and it becomes difficult to apply the desired physical properties to the workpiece202to be treated.

FIG. 17is a cross section of the heat treatment device300of the related art described in JP-A-2002-203804 (US-A-2004/0112885). As shown in this Figure, this heat treatment device300has, within a lamp housing301, a first lamp unit302that has an array of multiple U-shaped, double-ended lamps3022with equipment at both ends of the light emitting tubes to supply power to the filaments3021, arrayed parallel to and perpendicular to the plane of the paper, and a second lamp unit303located below the first lamp unit302, having an array of multiple straight-line, double-ended lamps3032with equipment at both ends of the light emitting tubes to supply power to the filaments3031, running along and perpendicular to the plane of the paper. Such an arrangement provides heat treatment of a workpiece to be treated304that is placed below the second lamp unit303.

The portions of the workpiece to be treated304that are in contact with the supporting ring305, which supports the workpiece to be treated304, tend to have a lower temperature than other portions. JP-A-2002-203804 (US-A-2004/0112885) describes a mechanism to control those U-shaped lamps belonging to the first lamp unit302that are positioned above the portions in contact to have a higher power, in order to raise the temperature of the portions in contact. Further, JP-A-2002-203804 (US-A-2004/0112885) describes the use of this heat treatment device300as outlined below. First, the semiconductor wafer that is the workpiece to be treated304is divided into multiple concentric zones with central symmetry. Then, by combining the irradiation patterns of the individual lamps of the first and second lamp units302,303, a combined irradiation distribution pattern that corresponds to those zones and that has central symmetry relative to the center of the semiconductor wafer is formed, and heating is done in response to the temperature changes of each zone. At that time, the semiconductor wafer that is the workpiece to be treated304is rotated to suppress the effect of variations in the intensity of light from the lamps. That is, zones located concentrically can be heated at individual illumination intensities.

Accordingly, the heat treatment device300described in JP-A-2002-203804 (US-A-2004/0112885) is capable of controlling temperature in narrow special regions on the workpiece to be treated304as long as those regions have central symmetry with respect to the center of the semiconductor wafer. Nevertheless, in the event that the special regions do not have central symmetry with respect to the center of the semiconductor wafer, it is not possible to solve the problem described above properly because heat treatment is done by rotating the semiconductor wafer.

Moreover, it is thought that the following problems could occur if this heat treatment device300were actually used. Specifically, a U-shaped lamp comprises a horizontal portion3023and a pair of vertical portions3024, but because only the horizontal portion3023where the filament3021is located contributes to light emission, the individual lamps are separated by spaces to a degree that cannot be ignored, and so it is conceivable that undesirable temperature distributions will occur in areas beneath the spaces.

That is, even though the illumination-intensity distributions of the lamps of the first and second lamp units302,303of the heat treatment device300are combined to form a synthesized distribution of the illuminance with central symmetry on the semiconductor wafer, the illuminance beneath the spaces mentioned above will change (e.g., drop) rapidly, and so even though heating is done in response to the temperature changes in each zone, it will conceivably be relatively difficult to reduce the temperature distribution that occurs in the vicinities beneath the spaces. Furthermore, with regard to this sort of heat treatment device300, there has been a trend in recent years to reduce as much as possible space (e.g., primarily with respect to height) for laying out the lamp units. Accordingly, if U-shaped lamps are used, space will be needed for the vertical portions3024of the lamps, which is not desirable from the perspective of space reduction.

FIG. 18is a perspective view of a conventional filament lamp400, described in JP-A-2006-279008 (US-A-2006/0197454), and which the present inventors proposed in a prior application to resolve the problems described above. This filament lamp400is constituted as outlined below. Both ends of the light emitting tube401of the filament lamp400are formed with hermetic seal areas4031,4032in which are embedded metal foils4021to4024. Within the light emitting tube401are multiple (e.g., two, as shown inFIG. 18) filament assemblies404,405, comprising filaments4041,4051and leads4042to4043,4052to4053that supply power to the filaments4041,4051. Here, when the filament assemblies404,405are placed in the light emitting tube401, they are arranged in order so that the filaments4041,4051extend along the length of the light emitting tube401.

In one filament assembly404, the lead4042that is connected to one end of the filament4041is electrically connected to the metal foil4021that is embedded in the seal area4031at one end of the light emitting tube401. Further, the lead4043that is connected to the other end of the filament4041in the filament assembly404is threaded through the through hole4091of insulator409, is covered by an insulating tube4044in the area that faces the filament4051of the other filament405, and is electrically connected to the metal foil4023that is embedded in the seal area4032at the other end of the light emitting tube401. Similarly, in the other filament assembly405, the lead4052that is connected to one end of the filament4051is electrically connected to the metal foil4023that is embedded in the seal area4032at one end of the light emitting tube401. Further, the lead4053that is connected to the other end of the filament4051in the filament assembly405is threaded through the through hole4092of insulator409, is covered by an insulating tube4054in the area that faces the filament4041of the one filament404, and is electrically connected to the metal foil4024that is embedded in the seal area4031at the other end of the light emitting tube401.

The ends of the metal foils4021to4024embedded in the seal portions4031,4032that are opposite the ends connected to the leads4042to4043,4052to4053of the filament assemblies404,405are connected to external leads4061to4064that project from the seal areas4031,4032. Accordingly, each filament assembly404,405is connected to two external leads4061to4062, and4063to4064by way of the metal foils4021to4022, and4023to4024. Power supplies4071,4072are connected to the filaments4041,4051by way of the external leads4061to4062, and4063to4064. It is possible, by this means, to supply power individually to the filaments4041,4051of the filament assemblies404,405of the filament lamp400.

Each filament4041,4051is supported, so that it does not contact the light emitting tube401, by circular anchors408that are sandwiched between the inner wall of the light emitting tube401and the insulating tubes4044,4054. Here, if there were contact between the filaments4041,4051and the inner wall of the light emitting tube401while the filament was emitting light, the light transmissivity of the light emitting tube401where the contact occurs would be impaired because of a loss of transparency of the light emitting tube401due to heat from the filaments4041,4051. The purpose of the anchors408is to prevent this problem. Multiple anchors408are placed along the length of the light emitting tube401for each filament4041,4051. Further, the anchors408are flexible so that the multiple filament assemblies404,405can be easily inserted into the light emitting tube401when the filament lamp400is produced. Further, a slight gap is left between the anchors408and the space between the inner wall of the light emitting tube401and the insulating tubes4044,4054.

This filament lamp400has multiple filaments4041,4051within the light emitting tube401and is constituted to provide individual control of the light emitted by each filament4041,4051. If such filament lamps400are arrayed in parallel rows and used as a light source in light-irradiation-type heat treatment device, it is possible to arrange filaments with higher precision with respect to the regions to be irradiated on the workpiece to be treated as compared to using conventional filament lamps having a single filament in the light emitting tube.

Accordingly, by means of light-irradiation-type heat treatment device using such filament lamps, it is possible to supply power individually to the multiple filaments, and so it is possible to irradiate with the desired irradiation distribution according to the characteristics of the workpiece to be treated even when the distribution of localized temperature variations on the workpiece to receive heat treatment is non-symmetrical with respect to the workpiece to be treated. Therefore, the workpiece to be treated can be heated evenly, even when the distribution of localized temperature variations on the workpiece to receive heat treatment is non-symmetrical with respect to the workpiece to be treated, and an even temperature distribution can be achieved across the entire irradiated surface of the workpiece to be treated.

Furthermore, when compared with the heat treatment device70that has U-shaped lamps described in JP-A-2002-203804 (US-A-2004/0112885), the above-described filament lamps can have a straight-line shape and so do not require the space corresponding to the vertical portion of U-shaped lamps, and so it is possible to reduce the size of the heat treatment device.

The present inventors fabricated light-irradiation-type heat-treatment device in which were mounted the filament lamps shown inFIG. 18, and found that the following problems occurred when the filament lamps were actually lit. In these filament lamps, the leads connected to the multiple filaments placed within the light emitting tubes were covered by insulating tubes. When the filament lamps were lit, however, it was learned that the problems explained below occurred because the insulating tubes absorbed light emitted by the filaments and reached high temperatures.

That is, in light-irradiation-type heat-treatment equipment in which are mounted filament lamps with insulation tubes, the workpiece to be treated is irradiated by light emitted by the insulation tubes that have reached a high temperature, in addition to light emitted by the filaments. In these filament lamps, however, the insulating tubes are located within the light emitting tube, separated from the inner surface of the light emitting tube; and because there is no way to avoid a temperature rise by the insulating tubes, it is not possible to suppress the light emitted by the insulation tubes that have reached a high temperature. Moreover, the irradiation intensity of the light emitted by these insulating tubes varies, depending on the temperature of the insulating tubes, and is also affected by various factors such as the distance between the insulating tube and filaments in proximity to the insulating tube, the thickness of the insulating tube, and the amount of power used for powering the filaments. It is very difficult, therefore, to control uniformly the intensity of light emitted by the insulating tubes.

In light-irradiation-type heat-treatment equipment in which were mounted the filament lamps shown inFIG. 18, therefore, the workpieces to be treated were irradiated by light of different irradiation intensities from the insulating tubes of the filament lamps, and so variations of the speed of temperature rise on the workpieces to be treated would occur even when heat treatment of the workpieces to be treated was conducted under the same operating conditions with light-irradiation-type heat-treatment equipment fabricated with the same specifications. It was not possible, therefore, to obtain the desired treatment characteristics.

“The same specifications” here means that each piece of light-irradiation-type heat treatment device had the same numbers of filament assemblies located in the filament lamps and the same numbers of filament lamps located in the lamp units. Moreover, the same placement of filament lamps in each lamp unit was used in the light-irradiation-type heat treatment device having the same specifications. “The same operating conditions” here means that the power used for powering the filament lamps located in the lamp units was the same, as well as the atmosphere in which the workpiece to be treated were located. For example, the type of gas and gas pressure were the same in each piece of light-irradiation-type heat treatment device.

These problems were prominent in filament lamps in which high power (e.g., 80 W/cm or more of power per unit length of filament) was used to power the filaments located in the light emitting tubes in order to quickly heat the workpiece to be treated, and filament lamps in which the inside diameter of the light emitting tube was no more that 2.5 times the outside diameter of the filament (e.g., when four or more filaments were placed in a light emitting tube with an inside diameter of 12 mm or less in order to place multiple filament lamps in a limited space with the purpose of controlling with high precision the temperature of the workpiece to be treated).

The problems above can be avoided, simply put, if the insulating tubes are removed from the light emitting tube. Nevertheless, if the insulating tubes are removed, putting the leads in the light emitting tube in a such an arrangement, the presence of numerous filament assemblies within the light emitting tube is liable to cause undesired discharge between filaments and the leads placed in the vicinity of the filaments, and between nearby leads among the multiple leads that surround a filament, which may result in the filament lamp becoming unusable because the leads can melt through. Another conceivable method is that of keeping the insulating tube from reaching a high temperature by using a light emitting tube with a larger inside diameter and increasing the separation between filaments and adjacent insulating tubes. However, when filament lamps are arranged with parallel tube axes, increasing the inside diameter of the light emitting tube would increase the separation between adjacent filaments in the direction perpendicular to the tube axes, which is liable to lead to deterioration of the distribution of illuminance on the workpiece to be treated. That method would also increase the size of the light-irradiation-type heat-treatment equipment if the desired number of filament lamps were included, and so in practical terms it cannot be adopted.

SUMMARY OF THE INVENTION

In view of the problem described above, the purpose of the present invention is to provide a filament lamp that assures insulation between a filament and the leads that surround that filament, and between leads in the vicinity of the filaments, so that unwanted discharge will not occur, and one in which there is no likelihood that unwanted light will be emitted. Another purpose of the present invention is to provide light-irradiation-type heat treatment device in which variations are not liable to occur during heat treatment of the workpiece to be treated.

The present invention adopts the following aspects to resolve the problem described above.

The first aspect includes a filament lamp having multiple filament assemblies, each comprising a coiled filament connected at both ends to leads that supply electrical power to the filament, the filaments being in a linear arrangement within a light emitting tube, which is formed with a hermetic seal area on at least one end, and extending along the tube axis of the light emitting tube, with power being supplied to each filament independently by means of electrical connection of the leads of the filament assemblies to multiple conductive pieces located in the seal area, in which there are within the light emitting tube an insulating wall between filaments and leads that has openings through which the leads pass, located along the tube axis in proximity to the inner wall of the light emitting tube, and multiple lead accommodation spaces, corresponding to the number of leads, formed to extend along the tube axis of the light emitting tube and divided by the light emitting tube and the insulating walls, with each lead connected to a filament passing through an opening in the insulating wall and placed without short circuits in its lead accommodation space.

The second aspect includes a filament lamp as described in the first aspect, in which the insulating wall comprises an inner tube fitted on the same axis as the light emitting tube.

The third aspect includes a filament lamp as described in the second aspect, in which multiple slots are formed on the outer surface of the inner tube, corresponding to the number of leads connected to their respective filaments, extending along the tube axis of the light emitting tube and separated from each other in the circumferential direction, and the lead accommodation spaces are formed by the slots and the inner surface of the light emitting tube.

The fourth aspect includes a filament lamp as described in the second aspect, in which multiple slots are formed on the inner surface of the light emitting tube, corresponding to the number of leads connected to their respective filaments, extending along the tube axis of the light emitting tube and separated from each other in the circumferential direction, and the lead accommodation spaces are formed by the slots and the outer surface of the inner tube.

The fifth aspect includes a filament lamp as described in any one of the second through the fourth aspects, in which openings are formed in the inner tube such that light emitted by the filaments is emitted without being obstructed.

The sixth aspect includes a filament lamp as described in the first aspect, in which multiple slots are formed on the inner surface of the light emitting tube, corresponding to the number of leads connected to their respective filaments, extending along the tube axis of the light emitting tube and separated from each other in the circumferential direction, the insulating wall comprises pairs of facing plates with the filaments sandwiched between them, and the lead accommodation spaces are formed by the slots and the plates.

The seventh aspect includes a filament lamp as described in any one of the first through the sixth aspects, in which the insulating wall is fused.

The eighth aspect includes a filament lamp as described in any one of the first through the seventh aspects, in which the light emitting tube and the insulating wall are fused along the tube axis of the light emitting tube.

The ninth aspect includes a filament lamp as described in any one of the first through the eighth aspects, in which the lead accommodation spaces are formed so that all leads of filaments other than a given filament are positioned in a region other than the region that includes at least that filament, which is enclosed, in a cross section perpendicular to the tube axis of the light emitting tube, by the tube wall of the light emitting tube and two circumscribed lines perpendicular to the filament.

The tenth aspect includes a filament lamp as described in any one of the first through the ninth aspects, in which the seal area is formed by putting a rod-shaped sealing insulator in place and, with multiple conductive pieces arrayed at intervals around the periphery of the sealing insulator, hermetically sealing the light emitting tube and the sealing insulator with the conductive pieces between them.

The eleventh aspect includes a light-irradiation-type heat treatment device fitted with a light source in which is located a filament lamp as described in any one of the first through the tenth aspects, the workpiece to be treated being heated by irradiation of the workpiece to be treated with light from that light source.

The twelfth aspect includes a light-irradiation-type heat treatment device fitted with a lamp unit in which are arrayed multiple filament lamps as described in any one of the first through the tenth aspects, the workpiece to be treated being heated by irradiation of the workpiece to be treated with light from that lamp unit.

Using the invention of the first aspect, advantageously, there is no likelihood of unwanted discharge between a filament and leads that are nearby in the direction perpendicular to the tube axis of the light emitting tube, and because the heat of the insulating wall is transferred to the light emitting tube and released to the air, the insulating tube does not reach a high temperature as in filament lamps of the related art, and so there is no likelihood that unwanted light other than from the filaments will be emitted. Moreover, the leads are located in lead accommodation spaces where they will not short circuit each other, and so it is possible to suppress unwanted discharge between adjacent leads. Advantageously, there is no likelihood that leads will melt through while the filament lamp is lit, and the filament lamp can be lit in a stable manner over a long period of time.

Using the inventions of the second and third aspects, the leads can be positioned in the desired positions with certainty, and because movement of the leads in the circumferential direction is regulated, even with repeated thermal expansion and contraction of the leads, the leads do not depart from their initial positions and the distribution of illuminance is not liable to change over time. Advantageously, the initial distribution of illuminance can be maintained for a long period of time.

Using the invention of the fourth aspect, leads can be reliably positioned in the desired positions, so that movement of the leads in the circumferential direction is regulated, even with repeated thermal expansion and contraction of the leads, and the leads do not depart from their initial positions. Moreover, because non-machining methods such as drawing or injection molding can be adopted, damage to light emitting tubes during manufacture of the filament lamps can be avoided and productivity can be increased.

Using the invention of the fifth aspect, light emitted by the filament is emitted without attenuation by the insulating wall, and so the desired heat treatment can be conducted without an excessive use of power in the filament.

Using the of the sixth aspect, light emitted by the filaments is not attenuated by the insulating wall, and so the desired heat treatment can be conducted without an excessive use of power in the filament. Moreover, the operation of passing the leads through the openings formed in the insulating wall and pulling them outward from the insulating wall during manufacture of the filament lamp can be facilitated by inserting the filaments into the inner tube.

Using the invention of the seventh and eighth aspects, thermal conduction from the insulating wall to the light emitting tube is promoted, and so it is possible to more reliably keep the insulating wall from reaching a high temperature and there is no likelihood of the emission of unwanted light other than from the filaments. In particular, the inner surface of the light emitting tube and the insulating wall are fused together along the tube axis of the light emitting tube, and so it is possible to increase the area of fusion of the light emitting tube and the inner wall and further encourage thermal conduction from the insulating wall to the light emitting tube. Moreover, even if the insulating wall reaches a higher temperature than the light emitting tube while the filament lamp is lit and the insulating wall expands more than the light emitting tube in the direction of the tube axis of the light emitting tube, the shearing force that works between the light emitting tube and the insulating wall is dispersed, and so there is no likelihood of damage to the fused area.

Using the invention of the ninth aspect, leads can be located in positions where there is no practical problem of shadows from the leads being cast on the workpiece to be treated, and so there is no likelihood of an adverse effect on the distribution of illuminance on the workpiece to be treated.

Using the invention of the tenth aspect, numerous conductive pieces can be placed on the periphery of the sealing insulator without contacting each other, and so even in a filament lamp that has numerous filaments to conduct highly precise temperature control for workpieces to be treated that have complex physical characteristics, it is possible to form a structure to feed power to the filament assemblies independently without enlarging the seal area.

Using the invention of the eleventh aspect, it is possible to realize light-irradiation-type heat-treatment equipment that cancels equipment-by-equipment variations of distribution of illuminance on the workpieces to be treated, by making use of the filament lamps described in any one of the first through ninth aspects.

Using the invention of the twelfth aspect, it is possible to realize light-irradiation-type heat-treatment equipment that cancels equipment-by-equipment variations of distribution of illuminance on the workpieces to be treated, by making use of lamp units in which are mounted the filament lamps described in any one of the first through ninth aspects.

DETAILED DESCRIPTION OF THE INVENTION

The first embodiment of this invention is explained usingFIGS. 1 through 6.FIG. 1is a perspective view showing the constitution of the filament lamp1involved in the invention of this embodiment. As shown inFIG. 1, the filament lamp1has a linear or other tubular light emitting tube3, made of quartz glass or another light-transparent material. Air-tight seal areas5a,5bare formed by fusing sealing insulators6a,6bon the light emitting tube2at both ends of the light emitting tube2. A tubular insulating wall/inner tube3, made of quartz glass or another light-transparent material and shorter in length in the direction of the tube axis of the light emitting tube2, is located on the same axis as the light emitting tube2in proximity to the inner surface of the light emitting tube2within the light emitting tube2, in which is sealed a halogen gas. For example, five filament assemblies41to45are located within this inner tube, and filaments411to451of the filament assemblies41to45are arranged in order extending along the tube axis.

FIGS. 2(a)-2(c) show cross sections of the filament lamp1of the invention of the first embodiment, cut across and along the tube axis, andFIG. 3is a perspective view showing the filament assemblies41to45with respect to the inner tube3of the filament lamp1.FIGS. 2(a) &2(b) are cross sections of the filament lamp1cut in the radial direction.FIG. 2(c) shows a cross section of the filament lamp1cut along the direction of the tube axis at line A-A′ inFIG. 2(a), and a cross section of the filament lamp1cut along the direction of the tube axis at line B-B′ inFIG. 2(b), and a front view of the filament lamp1as seen from C inFIG. 2(b).

As shown inFIGS. 2 and 3, slots311to315, the same in number as the filament assemblies41to45, are formed in the outer surface of the inner tube3, separated from each other in the circumferential direction and extending along the tube axis. So that the leads412to415connected to both ends of the filaments411to451can pass through, there are openings321a,321b, openings322a,322b, openings323a,323b, openings324a,324b, openings325a,325b, two for each filament, in the slots311to315. In such an inner tube3, slots311to315having openings321a,321b, openings322a,322b, openings323a,323b, openings324a,324b, openings325a,325bfor the passage of leads412to452are formed by machining quartz glass molded in tubular shape.

Locating such an inner tube3in proximity to the inner surface of the light emitting tube2forms lead accommodation spaces111to115to accommodate the leads412to452of the filament assemblies41to45, which are demarcated by the inner surface of the light emitting tube2and the slots311to315made in the inner tube3.

The filament assemblies located in the inner tube3comprise coiled filaments411to415and power feed leads412to452that are connected to both ends of the filaments411to415. The leads412to452comprise filament connectors4121ato4521a,4121bto4521bthat are connected to both ends of the filaments411to415and extend perpendicular to the tube axis, lead horizontal parts4122ato4522a,4122bto4522bthat are connected to the filament connectors4121ato4521a,4121bto4521band extend along the tube axis, and internal lead connectors4123ato4523a,4123bto4523bthat are connected to the lead horizontal parts4122ato4522a,4122bto4522band extend in the direction perpendicular to the tube axis and also connect to the internal leads71ato75a,71bto75bthat are fixed in the seal areas5a,5b. The number of filament assemblies41to45can be adjusted as is appropriate to the dimensions, physical characteristics, etc., of the workpiece to be treated.

The filament assemblies41to45are installed in the inner tube3such that all the filaments411to415are accommodated within the inner tube3and the filaments411to415are positioned on the central axis of the light emitting tube2. For example, as shown inFIG. 3, in one set of leads connected to one end of the filaments411to451, the filament connectors4121ato4521aextend in directions perpendicular to the tube axis and pass through the openings321ato325ain the slots311to315of the inner tube3, and the lead horizontal parts4122ato4522aare positioned in the slots311to315of the inner tube3and project outward from the outer end face of the inner tube3along the tube axis toward one seal area5a. Moreover, in the other set of leads connected to the other end of the filaments411to451, the filament connectors4121bto4521bextend in directions perpendicular to the tube axis and pass through the openings321bto325bin the slots311to315of the inner tube3, and the lead horizontal parts4122bto4522bare positioned in the same slots311to315of the inner tube3as the one set and project outward from the outer end face of the inner tube3along the tube axis toward the other seal area5b.

The filaments411to451are supported within the inner tube3, such that they do not contact the inner wall of the inner tube3, for example, by ring-shaped anchors (not shown) that are fitted to press against the inner wall of the inner tube3. One anchor is fixed as a single piece with each filament411to451. By fitting such anchors, it is possible to prevent the occurrence of the problem of the inner tube3losing transparency due to contact between the inner wall of the inner tube3and the filaments411to451that reach high temperatures when lit.

The seal areas5a,5bformed at both ends of the light emitting tube2have a shrink seal structure formed to have a smaller outside diameter than other areas by inserting cylindrical sealing insulators6a,6bmade of quartz glass, for example, inside the constituent material of the light emitting tube2and using such means as a burner to heat the outer surface of the constituent material of the light emitting tube2. On the outer surface of the sealing insulator6a,6ba number of foils81ato85a,81bto85bequal to the number of filament assemblies41to45, five for example, are placed at roughly equal intervals and parallel along the length of the sealing insulator6a,6b. To avoid folding, foils81ato85a,81bto85bthat are shorter than the sealing insulators6a,6bare used.

In the seal areas5a,5b, the internal leads71ato75a,71bto75bthat are connected to the leads412to452of the filament assemblies41to45are fixed and connected to the metal foils81ato85a,81bto85b. For the internal leads71ato75a,71bto75b, their base ends are embedded in the seal areas5a,5band are connected, by welding, for example, to the tip ends of the metal foils81ato85a,81bto85b, and their tip ends that project into the light emitting tube2are connected, by welding, for example, to the leads412,452of the filament assemblies41to45. For the external leads91ato95a,91bto95a, their tip ends are embedded in the seal areas5a,5band are connected by welding, for example, to the base ends of the metal foils81ato85a,81bto85b, and their base ends project outward from the ends of the light emitting tube2in the direction of the tube axis. The internal leads71ato75a, the metal foils81ato85, and the external leads91ato95amake up the conductive pieces101ato105a, and the internal leads71bto75b, the metal foils81bto85b, and the external leads91bto95bmake up the conductive pieces101bto105b.

FIG. 4(a) is an expanded perspective view within the seal area5ashown inFIG. 1.FIG. 4(b) is a cross section within the seal area5ataken at line A-A′ ofFIG. 4(a), andFIG. 4(c) is a cross section within the seal area5ataken at line B-B′ ofFIG. 4(a).

UsingFIG. 4(a) to explain the constitution within the seal area5ain greater detail, multiple slots611ato615athat are separated from each other in the circumferential direction and extend in the lengthwise direction of the sealing insulator6aon the side of the filament assemblies41to45and multiple slots621ato625athat are separated from each other in the circumferential direction and extend in the lengthwise direction of the sealing insulator6aon the side of the external leads91ato95aare formed on the sealing insulator6a, and by which means high areas are formed to position the internal leads71ato75aand the external leads91ato95a. The internal leads71ato75aare placed along the slots611ato615aso that the outer end faces on the base ends are in contact with the high areas, and the external leads91ato95aare placed along the slots621ato625aso that the outer end faces on the tip ends are in contact with the high areas. By this means, the outermost faces of the internal leads71ato75aand the external leads91ato95aare positioned at the same circumference as the trunk of the sealing insulator6a. The internal leads71ato75aand the external leads91ato95apositioned in this way are connected to the metal foils81ato85athat are located on the periphery of the trunk of the sealing insulator6a. The external leads91ato95athat project from the end face of the light emitting tube2are connected to a power supply (not shown) and feed power independently to the filaments411to451of the filament assemblies41to45, by which means it is possible to control the lighting of each filament411to451individually. The constitution within the seal area5bis the same as that within the seal area5aexplained above.

Thus, the sealing insulators6a,6bare placed inside the light emitting tube2and the seal areas5a,5bare formed, by which means the periphery of the cylindrical sealing insulators6a,6bcan be used to put numerous metal foils81ato85a,81bto85bin place without contacting each other. Consequently, it is possible to reliably form a structure to feed power to each filament assembly41to45independently without enlarging the seal areas5a,5b, even when the filament lamp1has numerous filament assemblies41to45. In particular, in comparison with the formation of flat seals by the pinch seal method, the size of the seal area can be made smaller even if numerous metal foils are present, advantageously, preferable from the perspective of conserving space.

Using a filament lamp1that has seal areas5a,5bconstituted with this sort of sealing insulator6a,6b, the filaments412to452of the filament assemblies41to45located in the slots311to315of the inner tube3are fixed in place relative to the internal leads71ato75a,71bto75bthat have been fixed in the slots611ato615a,611bto615bmade in the sealing insulators6a,6b. It is possible, therefore, to regulate rotation of the inner tube3in the circumferential direction, even if the filament lamp1is subjected to vibration or shocks during transportation or while lighting. In particular, if the leads412to452that project from the end faces of the inner tube3toward the seal areas5a,5bcontract in length, rotation of the inner tube3in the circumferential direction can be reliable stopped, and so it is preferable that the end face of the inner tube, rather than the end faces on the seal area side of the end-most two filaments among the five filament assemblies41to45arranged along the tube axis, be located toward the seal areas.

In this sort of filament lamp1, for any filament (e.g., filament411), all of the leads (e.g., leads422to452) of the filaments (e.g., filaments421to451) other than that filament (e.g., filament411) are preferably positioned within a specified region within the light emitting tube2. A specific example is explained below usingFIG. 5.

FIG. 5is a cross section of the filament lamp1, cut in the radial direction, of the invention of this embodiment, used to explain the positional relationship between the filaments411to451and the leads412to452. In a cross section of which the plane is perpendicular to the central axis of, for example, the filament411, as shown inFIG. 5, all of the leads422to452of the filaments421to451other than that filament411are positioned outside the region (also referred to as “effective light extraction region” hereafter) that is bounded by the tube wall of the light emitting tube2and two circumscribed lines X, Y that are perpendicular to the filament411, which is the region within which at least the filament411is included. Further, the leads412to452of the filaments411to451are located as symmetrically as possible with respect to the filaments411to451, and the leads412to452are not present in the region opposite the effective light extraction region either.

In order to realize such a positional relationship between the filaments411to451and the leads412to452, slots311to315are formed in the inner tube3that is located within the light emitting tub2only in regions other than the region that is bounded by the tube wall of the light emitting tube2and two circumscribed lines X, Y that are perpendicular to the filament411, which is the region within which at least the filaments411to451are included. In the sealing insulators6a,6b, moreover, the slots611ato615a,611bto615bin which the internal leads71ato75a,71bto75bare located are formed to correspond to the slots311to315in the inner tube3.

By means of realization of such a positional relationship between the filaments411to451and the leads412to452, it is possible to extract effectively the light directly emitted by a filament (e.g., the filament411) without it being blocked by the leads (e.g., the leads422to452) of the other filaments (e.g., the filaments421to451), and so the distribution of illuminance on the workpiece to be treated is not liable to deteriorate due to shadows that leads (e.g., the leads422to452) cast on the workpiece to be treated. In a filament lamp1constituted such that there are four or more filament assemblies41to45located in the light emitting tube2and the angle made by the circumscribed lines common to the filaments411to451and the leads412to452is from 10° to 60° in particular, the effect of shadows of the leads412to452cast on the workpiece to be treated would be marked, and so it is particularly effective to place the filaments411to451and the leads412to452so as to fulfill the positional relationship described above. A numerical example of such a filament lamp1is presented below.

The light emitting tube2has an outside diameter from 10 mm to 40 mm and a length from several tens of mm to about 800 mm, depending on the size of the workpiece to be treated, the distance from the filament lamp1to the workpiece to be treated, and the placement of the lamps within the lamp units. The filament assemblies41to45use solid wire of about 0.05 mm to 1 mm. In the event that this embodiment irradiates a 300 mm diameter silicon wafer from a distance of 50 mm, the light emitting tube2is 28 mm in diameter and 560 mm long, filament wire with a diameter of 0.5 mm is used, and connected to both ends of the filaments411to451that are 140 mm at the longest and are formed with an outside diameter of 8 mm are leads412to452that have a larger diameter than the filament wire, for example 0.8 mm. Now, the outside diameter of the filament is not restricted to 8 mm; depending on the required power and the filament temperature, and it can be from about 0.4 mm to about 20 mm. The maximum rated current value per filament is decided in accordance with the required temperature rise characteristics of the workpiece to be treated and permissible current value of the metal foil in the seal area (e.g.; it is 25 A in this embodiment).

The inner tube3, in this embodiment, has an outside diameter from 24 mm to 24.5 mm and a length from 400 mm to 470 mm, wherein the gap from the inner surface of the light emitting tube2is preferably 0.7 mm or less. In the gap between the outer surface of the inner tube3and the inner surface of the light emitting tube2, the lead accommodation spaces111to115are formed by the slots311to315of the inner tube3and the inner surface of the light emitting tube2, so it must at least be smaller than the outside diameter of the leads412to452, but considering the effect of thermal conductivity, it is particularly desirable that it be 0.5 mm or less with respect to the outer diameter of the light emitting tube2. Further, the slots311to315made in the inner tube3are formed with a width of 1.0 mm to 1.5 mm, a depth of 1.3 mm to 1.6 mm, and a separation of at least 2 mm from each other. The separation between adjacent slots311to315is set greater than for the discharge-startup voltage, and so that the leads412to452are kept in a region other than the effective light extraction region. In the case of this embodiment, the lamp was filled with argon gas at a pressure of 0.5 atmosphere, so the separation between the slots311to315has to be at least 0.5 mm so that the lamp can be used without discharge at the commercial power of 200 V (e.g., 1 mm or more is preferable in consideration of a safety margin). In order to keep the leads412to452in a region other than the effective light extraction region, a separation of 7.5 mm or less is preferable in the event that three leads432,442,452are placed on one side of an inner tube with an outside diameter of 24 mm, as shown in the left half ofFIG. 5.

In the event that either the outer surface of the inner tube3is in contact with the inner surface of the light emitting tube2or the gap between the outer surface of the inner tube3and the inner surface of the light emitting tube2is 0.5 mm or less, when the inner tube3is irradiated with light emitted by the filaments411to451, heat from the inner tube3is transferred to the light emitting tube2that is close to the inner tube3, and so it is possible to reliably prevent the inner tube3from reaching a high temperature. If the separation between adjacent slots311to315formed in the inner tube3is 1 mm or greater, unwanted discharge between the adjacent leads412to452can be reliably prevented.

As stated above, using the filament lamp1of the invention of this embodiment, power basically can be fed independently to multiple filaments411to451by way of conductive pieces101ato105a,101bto105b, and so it is possible to heat the workpiece to be treated evenly, even if the distribution of the extent of localized temperature change on the workpiece being treated is non-symmetrical with respect to the shape of the substrate, and so it is possible to realize a uniform temperature distribution across the entire workpiece to be treated.

In addition, the inner tube3is located in proximity to the inner surface of the light emitting tube2, so that the tubular insulating wall3can be prevented from reaching a high temperature when the filament lamp1is lit. It is possible, therefore, to reliably eliminate the problem of emission of unwanted light other than from the filaments411to415.

Further, the inner tube3is interposed between the filaments411to415and the leads412to452; the leads412to452of the filament assemblies41to45are located in the lead accommodation spaces111to115demarcated by the inner surface of the light emitting tube2and the slots311to315in the inner tube3where they will not short circuit, and so the occurrence of unwanted discharge between a filament (e.g., the filament411) and the leads (e.g., leads422to452) in proximity to that filament (e.g., the filament411), or between adjacent leads412to452can be reliably prevented.

Moreover, the leads412to452of the filament assemblies41to45are located in the lead accommodation spaces111to115demarcated by the inner surface of the light emitting tube2and the slots311to315in the inner tube3, and so even with repeated thermal expansion and contraction of the leads412to415when the filament lamp1is lit, the leads412to415will not slip from their original position because movement of the leads412to415in the circumferential direction is regulated. Therefore, the distribution of illuminance is not liable to change over time, and so the initial distribution of illuminance can be maintained for a long time period.

FIG. 6shows a constitution that can be adopted in the filament lamp1of the invention of the first embodiment, whereinFIG. 6is a perspective view showing the placement of the filament assemblies41to45with respect to inner tube constituent members121,122. As shown inFIG. 6, inner tube constituent members121,122, which are in the shape of half cylinders cut in the radial direction, segmented in two parts in the radial direction, are in proximity to the inner surface of the light emitting tube2instead of the inner tube3shown inFIG. 3. Two slots311,312that extend along the tube axis and are separated in the circumferential direction are formed on the outer surface of one inner tube constituent member121. Similarly, three slots313,314,315that extend along the tube axis and are separated in the circumferential direction are formed on the outer surface of the other inner tube constituent member122. Two openings321a,321b, openings322a,322b, openings323a,323b, openings324a,324b, openings325a,325b, are formed in each of the slots311to312,313to315made in the inner tube constituent members121,122.

Using multiply divided inner tube constituent members121,122in this way, it is possible to perform separately for each inner tube constituent member121,122the work of passing the leads412to452of the filament assemblies41to45through the openings321a,321b, openings322a,322b, openings323a,323b, openings324a,324b, and openings325a,325bmade in the slots311to312,313to315of the inner tube constituent members121,122. In filament lamps1that have numerous filament assemblies41to45, therefore, the work of passing the leads412to452of the filament assemblies41to45through the openings321a,321b, openings322a,322b, openings323a,323b, openings324a,324b, and openings325a,325bmade in the slots311to312,313to315of the inner tube constituent members121,122can be done with good efficiency, as compared to a tubular inner tube3that is not multiply divided. By placing one inner tube constituent member121and the other inner tube constituent member122inside the light emitting tube2with a gap between them, if the inner tube constituent members121,122expand in the circumferential direction while the filament lamp1is lit, the expansion is absorbed by the space between the facing inner tube constituent members121,122, and so it is possible to reliably prevent damage to the inner tube constituent members121,122.

The second embodiment of this invention is explained usingFIGS. 7(a)-7(c), which are front cross-sectional views showing the filament lamp1of the invention of this embodiment, sectioned across and along the tube axis.FIGS. 7(a) &7(b) are cross sections of the filament lamp1cut in the radial direction.FIG. 7(c) has a cross section of the filament lamp1cut along the direction of the tube axis at line A-A′ inFIG. 7(a), a cross section of the filament lamp1cut along the direction of the tube axis at line B-B′ inFIG. 7(b), and a front view of the filament lamp1as seen from C inFIG. 7(b).

As shown inFIGS. 7(a)-7(c), the filament lamp1of the invention of this embodiment is not limited to the mode of lead accommodation spaces111to115formed by multiple slots311to315in the inner tube3and the inner surface of the light emitting tube2, like the filament lamp1of the invention of the first embodiment. In this filament lamp1, multiple slots131to135are formed in the inner surface of the light emitting tube13, extending along the tube axis and separated from each other in the circumferential direction. By placing an inner tube14close to the inner surface of this light emitting tube13, one forms multiple lead accommodation spaces111to115demarcated by the slots131to135of the light emitting tube13and the outer surface of the inner tube14. The slots131to135formed in the inner surface of the light emitting tube13satisfy the positional relationship between a filament (e.g., the filament411) and the leads (e.g., leads422to452) of the filaments (e.g., the filaments421to451) other than that filament (e.g., the filament411), and as explained with respect toFIG. 5.

Two openings141a,141b, openings142a,142b, openings143a,143b, openings144a,144b, and openings145a,145bfor the passage of leads412to452are made in the inner tube14at points corresponding to each of the slots131to135in the light emitting tube13. The inner tube14can be constituted without slots in its outer surface, or it can be constituted with slots in its outer surface corresponding to the slots131to135in the light emitting tube13.

The filament assemblies41to45have all their filaments411to451accommodated within the inner tube14, wherein the filaments411to451are mounted in the inner tube14so that they are positioned on the central axis of the light emitting tube13. That is, the filament connectors4121ato4521aof one set of leads connected to one end of the filaments411to451extend in a direction perpendicular to the tube axis and pass through the openings141ato145ain the inner tube14, and the lead horizontal parts4122ato4522aof the one set of leads are placed in the slots131to13of the light emitting tube13and extend outward in the direction of the tube axis from the end face of the inner tube14toward the one seal area5a. Moreover, the filament connectors4121bto4521bof the other set of leads connected to the other end of the filaments411to451extend in a direction perpendicular to the tube axis and pass through the openings141bto145bin the inner tube14, and the lead horizontal parts4122bto4522bof the other set of leads are placed in the slots131to13of the light emitting tube13and extend outward in the direction of the tube axis from the end face of the inner tube14toward the other seal area5b, as shown inFIGS. 7(a)-7(c).

As described above, using the filament lamp1of the invention of the second embodiment, basically the same results can be anticipated as with the filament lamp1of the invention of the first embodiment. Moreover, the light emitting tube13that has slots131to135on its inner surface can be constituted by the methods of drawing or injection molding. Advantageously, it is not necessary to form the slots on the inner surface of the light emitting tube13by a subsequent mechanical process such as machining, and so it is possible to reduce the cost and effort required in production and the risk of damage during machining.

The third embodiment of this invention is explained using8(a)-8(c), which are front cross-sectional views showing the filament lamp1of the invention of this embodiment, sectioned across and along the tube axis.FIGS. 8(a) &8(b) are cross sections of the filament lamp1cut in the radial direction.FIG. 8(c) has a cross section of the filament lamp1cut along the direction of the tube axis at line A-A′ inFIG. 8(a), a cross section of the filament lamp1cut along the direction of the tube axis at line B-B′ inFIG. 8(b), and a front view of the filament lamp1as seen from C inFIG. 8(b).

As shown inFIGS. 8(a)-8(c), in the filament lamp1, multiple slots131to135are formed in the inner surface of the light emitting tube13, extending along the tube axis and separated from each other in the circumferential direction. By placing an inner tube15close to the inner surface of this light emitting tube13, one forms multiple lead accommodation spaces111to115demarcated by the slots131to135of the light emitting tube13and the outer surface of the inner tube15. The slots131to135formed in the inner surface of the light emitting tube13satisfy the positional relationship between a filament (e.g., the filament411) and the leads (e.g., leads422to452) of the filaments (e.g., the filaments421to451) other than that filament (e.g., the filament411), as explained with respect toFIG. 5.

Moreover, the inner tube15of the filament lamp1has an opening158that is “C” shaped in a cross section perpendicular to the tube axis extending along the tube axis of the light emitting tube13on the light extraction side. Two openings151a,151b, openings152a,152b, openings153a,153b, openings154a,154b, and openings155a,155bfor the passage of leads412to452of the filament assemblies41to45are made in the inner tube15at points corresponding to each of the slots131to135in the light emitting tube13. Further, the edges of the opening158are positioned in a region other than the effective light extraction region described with respect toFIG. 5. Specifically, the opening158is formed in the inner tube15such that an angle of 80° to 90° is formed by the straight circumscribed lines X, Y that connect the filaments411to451to the edges of the opening in the inner tube15.

The method of installing the filament assemblies41to45of this filament lamp1is similar to that of the filament lamp1of the second embodiment described with respect toFIG. 7. However, instead of forming the slots in the inner surface of the light emitting tube13, it is possible to form the slots in the outer surface of the inner tube15, as shown inFIGS. 8(a)-8(c).

As stated above, using the filament lamp1of the invention of the third embodiment, basically the same results can be anticipated as with the filament lamp1of the invention of the first embodiment. Moreover, because the light emitted by the filaments411to451is not absorbed or reflected by the inner tube15, the power used in the filaments411to451can be minimized.

FIGS. 9(a)-9(c) are front cross-sectional views showing the filament lamp1of the invention of this embodiment, sectioned across and along the tube axis.FIG. 9(a) is a cross section of the filament lamp1cut in the radial direction at line A-A′ inFIG. 9(c), andFIG. 9(a) is a cross section of the filament lamp1cut in the radial direction at line B-B′ inFIG. 9(c).FIG. 9(c) has a cross section of the filament lamp1cut along the direction of the tube axis at line P-P′ inFIG. 9(a), a cross section of the filament lamp1cut along the direction of the tube axis at line Q-Q′ inFIG. 9(b), a cross section of the filament lamp1cut along the direction of the tube axis at line R-R′ inFIG. 9(b) and a front view of the filament lamp1as seen from S inFIG. 9(a).

As shown inFIGS. 9(a)-9(c), this filament lamp1has five filament assemblies41to45located within a linear light emitting tube16that is square in a cross section taken perpendicular to the tube axis. The filaments411to451of the filament assemblies41to45extend along the tube axis and are arrayed in order in the direction of the tube axis, and the leads412to451of the filament assemblies41to45are located along the inner walls on both sides of the light emitting tube16. Seal areas5a,5bon both ends of the light emitting tube16are formed with a cross section that is circular in the direction perpendicular to the tube axis, like the seal areas5a,5bdescribed in the first through third embodiments. A pair of insulating walls171,172that are rectangular in a cross section perpendicular to the tube axis and that extend along the tube axis of the light emitting tube16, with the filaments411to451sandwiched and separated, are located within the light emitting tube16. The insulating walls171,172are made of an insulating material such as quartz glass, and are located along the inner walls on both sides of the light emitting tube16, between the filaments411to451and the leads412to452.

The constitution of this filament lamp1is explained below in greater detail. Multiple slots1611to1612, and1621to1623to position the leads412to452of the filament assemblies41to45are formed in the inner surface of the light emitting tube16, and which extend along the tube axis and are separated in the circumferential direction. These slots1611to1612, and1621to1623fulfill the positional relationship between a filament (e.g., the filament411) and the leads (e.g., leads422to452) of the filaments (e.g., the filaments421to451) other than that filament (e.g., the filament411), as explained with respect toFIG. 5. The insulating walls171,172have two openings1711a,1711b, openings1712a,1712b, openings1721a,1721b, openings1722a,1722b, and openings1723a,1723bmade at points corresponding to each of the slots1611to1612, and1621to1623in the light emitting tube16, and with their outer edges in the direction perpendicular to the tube axis located in the light emitting tube16so that they are positioned in regions other than the effective light extraction region described with respect toFIG. 5.

Slots1611to1612, and1621to1623to position the leads412to452are formed on the inner surfaces within the light emitting tube16, by which means a paired first concave/convex surface161and second concave/convex surface162with shapes that are uneven in cross section perpendicular to the tube axis face two sides with the filaments411to451between them. There are provided in the light emitting tube16, in addition to the first concave/convex surface161and second concave/convex surface162, slots1631to1632, and1641to1642to position the insulating walls171,172, by which means a paired third concave/convex surface163and fourth concave/convex surface164with shapes that are uneven in cross section perpendicular to the tube axis face two sides with the filaments411to451between them. In the direction perpendicular to the tube axis, the concave/convex surfaces formed on the third concave/convex surface163and fourth concave/convex surface164face across a gap that is slightly narrower than the width of the insulating walls171,172in the direction perpendicular to the tube axis.

The insulating walls171,172are placed with the edges in the direction perpendicular to the tube axis adjoining concave portions of the third concave/convex surface163and the fourth concave/convex surface164. One pair of edges adjoins convex portions of the third concave/convex surface163and the fourth concave/convex surface164, and the other edges adjoin the first concave/convex surface161and the second concave/convex surface162. Rotation in the circumferential direction within the light emitting tube16is regulated by this means. Within the light emitting tube16, the insulating walls171,172are placed to cover all the slots1611to1612, and1621to1623made in the first concave/convex surface161and the second concave/convex surface162, by which means lead accommodation spaces111to115to accommodate the leads412to452of the filaments411to451are formed and demarcated by the slots1611to1612, and1621to1623in the inner surface of the light emitting tube16and the other edges of the insulating walls171,172.

The filament assemblies41to45are installed with the insulating walls171,172on both sides and the filaments411to451on the center line of the light emitting tube16, in the following manner. For example, as shown inFIGS. 9(a)-9(c), the filament connectors4121ato4521aof one set of leads connected to one end of the filaments411to451extend in a direction perpendicular to the tube axis and pass through one set of openings1711ato1712a, and1721ato1723ain the insulating walls171,172, and the lead horizontal parts4122ato4522aof one set of leads is placed in the slots1611to1612, and1621to1623on the inner surface of the light emitting tube16and project outward in the direction of the tube axis from the ends of the insulating walls171,172toward one seal area5a. Moreover, the filament connectors4121bto4521bof the other leads connected to the other end of the filaments411to451extend in a direction perpendicular to the tube axis and pass through the other openings1711bto1712b, and1721bto1723bin the insulating walls171,172, and the lead horizontal parts4122bto4522bof the other leads is placed in the slots1611to1612, and1621to1623on the inner surface of the light emitting tube16and project outward in the direction of the tube axis from the ends of the insulating walls171,172toward the other seal area5b.

Examples of numerical values for such a filament lamp are explained below. For example, the numerical values for the filaments411to451and the leads412to452of the filament assemblies41to45are similar to the filament lamp1of the invention of the first embodiment. The light emitting tube16has a width of 10 mm to 40 mm in the direction perpendicular to the tube axis, and a length from several tens to about 800 mm, wherein these are determined in accordance with the size of the workpiece to be treated, the distance from the lamp to the workpiece to be treated, and the position of the lamp within the lamp unit (e.g., the width is 28 mm and the length is 560 mm). The insulating walls171,172have a width in the direction perpendicular to the tube axis (the up/down direction in the cross section inFIG. 9(b)) of 24.5 to 25.5 mm and a length in the direction of the tube axis (the depth direction inFIG. 9(b)) of 400 to 470 mm, and a thickness (the left/right direction inFIG. 9(b)) of 0.5 to 1.2 mm. The insulating walls171,172typically must be in proximity to the concave/convex surfaces of the first concave/convex surface161and the second concave/convex surface162, separated by a gap that is in any case smaller than the outside diameter of the leads412to452, preferably either touching the convexities of the first concave/convex surface161and the second concave/convex surface162, or separated from the convexities of the first concave/convex surface161and the second concave/convex surface162by no more than 0.7 mm. The convexities of the first concave/convex surface161and the second concave/convex surface162face across a gap of 24 mm.

As stated above, using the filament lamp1of the invention of the fourth embodiment, basically the same results can be anticipated as with the filament lamp1of the invention of the first through third embodiments. Moreover, a cross section of the light emitting tube16in the direction perpendicular to the tube axis is that of a rectangular or square cornered tube, and so numerous leads can be placed within the light emitting tube more easily than in a light emitting tube that is a round tube with the same diameter as the cornered tube. Therefore, filament lamps that can realize highly precise control of temperatures on the workpiece to be treated can be manufactured more easily.

In the filament lamps of the inventions of the first through fourth embodiments, tubular insulating walls or plate-shaped insulating walls are placed in proximity to the inner surface of the light emitting tube and the heat of the tubular insulating walls or plate-shaped insulating walls can be transferred to the light emitting tube. By this means, the tubular insulating walls or plate-shaped insulating walls are kept from reaching high temperatures. By adopting the filament lamp1constitution shown inFIGS. 10-12below, however, it is possible to transfer the heat of the tubular insulating walls or plate-shaped insulating walls to the light emitting tube more efficiently.

The fifth embodiment of this invention is explained usingFIGS. 10(a)-10(c), which are front cross-sectional views showing the filament lamp1of the invention of the fifth embodiment, sectioned across and along the tube axis.FIG. 10(a) is a cross section of the filament lamp1taken in the radial direction at line A-A′ ofFIG. 10(c),FIG. 10(b) is a cross section of the filament lamp1taken in the radial direction at line B-B′ ofFIG. 10(c), andFIG. 10(c) is a cross section of the filament lamp1taken along the tube axis.

As shown inFIGS. 10(a)-10(c), the filament lamp1of the invention of this embodiment is one with an improvement added to the filament lamp1of the invention of the first embodiment, wherein the constitution is the same as that of the filament lamp1of the invention of the first embodiment except that the light emitting tube2and the inner tube3are fused together. This filament lamp1has an inner tube3located on the same axis as and in proximity to the inner surface of the light emitting tube2, and the light emitting tube2and the inner tube3are partially fused in the circumferential direction by means of heating the outer surface of the light emitting tube2, for example, with a burner. As shown inFIG. 10(a), the inner surface of the light emitting tube2and the outer surface of the inner tube3are in contact at the points where the light emitting tube2and the inner tube3are fused. As shown inFIG. 10(b), on the other hand, spaces are formed between the inner surface of the light emitting tube2and the outer surface of the inner tube3at the points where the light emitting tube2and the inner tube3are not fused.

By fusing the light emitting tube2and the inner tube3together in this way, the heat from the inner tube3can be efficiently transferred to the light emitting tube2from the fused region18, so that it is possible to more reliably stop the inner tube3from reaching a high temperature. Moreover, because the inner tube3is fixed to the light emitting tube2, rotation of the inner tube3in the circumferential direction can be regulated more reliably, so that the distribution of illuminance on the workpiece to be treated is not liable to deteriorate due to movement in the positions of the leads412to452of the filament assemblies41to45, and the initial distribution of illuminance can be maintained for a long period of time. In filament lamps1in which the lead accommodation spaces111to115are formed by slots311to315in the inner tube3and the inside surface of the light emitting tube2, especially, it is preferable that the light emitting tube2and the inner tube3be fused together. The area of the fused region18is determined in consideration of the power employed in the filaments411to451.

As shown inFIGS. 10(a)-10(c), the light emitting tube2and the inner tube3are not fused except in the regions that correspond to spaces between the filaments411to451that are adjacent in the direction of the tube axis. For example, they are fused in the fused regions18where the light emitting tube2and the inner tube3are marked off by the circumscribed line drawn in a direction perpendicular to the tube axis from the outer edge of one filament (e.g., the filament421) and the circumscribed line drawn in a direction perpendicular to the tube axis from the outer edge of another filament (e.g., the filament431) that faces the end of the one filament (e.g., the filament421), and are not fused in other regions. By means of such a construction, the light emitting tube2is constricted primarily in areas where between one of filaments411to452and the next, where light does not shine, and so it can be anticipated that unwanted condensing and diffusing of light by the curvature of the glass can be minimized.

In the filament lamp1using inner tube constituent members121,122that are multiply divided in the circumferential direction as described with respect toFIG. 6of the first embodiment or in the filament lamp1using a light emitting tube13having multiple slots131to135on its inner surface as described with respect toFIG. 7of the second embodiment, the same effects as noted above can naturally be anticipated by fusing the light emitting tube2and the inner tube constituent members121,122or the light emitting tube13and the inner tube3.

The sixth embodiment of this invention is explained usingFIGS. 11(a)-11(c), which are front cross-sectional views showing the filament lamp1of the invention of this embodiment, sectioned across and along the tube axis.FIGS. 11(a) & (b) are cross sections of the filament lamp1cut in the radial direction.FIG. 11(c) has a cross section of the filament lamp1cut along the direction of the tube axis at line A-A′ inFIG. 11(a), a cross section of the filament lamp1cut along the direction of the tube axis at line B-B′ inFIG. 11(b), and a front view of the filament lamp1as seen from C inFIG. 11(b).

As shown inFIGS. 11(a)-11(c), the filament lamp1of the invention of this embodiment is one with an improvement added to the filament lamp1of the invention of the third embodiment, wherein the constitution is the same as that of the filament lamp1of the invention of the third embodiment except that the light emitting tube13and the inner tube15are fused. In this filament lamp1, an inner tube15is placed on the same axis as and in proximity to the inner surface of the light emitting tube13, and the light emitting tube13and the inner tube15are partially fused in the direction of the tube axis by heating the outer surface of the light emitting tube13in the direction of the tube axis, for example, with a burner. At the points where the light emitting tube13and the inner tube15are fused, as shown inFIG. 11(a), the outer surface of the inner tube15is in contact with the inner surface of the light emitting tube13. On the other hand, at the points where the light emitting tube13and the inner tube15are not fused, as shown inFIG. 11(b), a space is formed between the outer surface of the inner tube15and the inner surface of the light emitting tube13.

Using the filament lamp1of the invention of this embodiment, the light emitting tube13and the inner tube15are fused, by which means it is possible to anticipate the following effects. First, it is possible to increase the fused area, and so it is possible to promote better heat transfer from the inner tube15to the light emitting tube13, and the inner tube15can be more reliably kept from reaching a high temperature. Second, the inner tube15is hotter than the light emitting tube13when the filament lamp1is lit, and the amount of thermal expansion is greater in the inner tube15than in the light emitting tube13, and so it is possible to reliably eliminate the likelihood of damage to the fused area due to shearing force working between the light emitting tube13and the inner tube15. In the event that the light emitting tube13is longer in the direction of the tube axis because there are four or more filament assemblies41to45, especially, it is preferable to fuse the light emitting tube13and the inner tube15in the direction of the tube axis.

The seventh embodiment of this invention is explained usingFIGS. 12(a)-12(b), which are front cross-sectional views showing the filament lamp1of the invention of this embodiment, sectioned across and along the tube axis.FIG. 12(a) is a cross section of the filament lamp1cut in the radial direction.FIG. 12(b) has a cross section of the filament lamp1cut along the direction of the tube axis at line T-T′ inFIG. 12(a).

As shown inFIGS. 12(a)-12(b), the filament lamp1of the invention of this embodiment is one with an improvement added to the filament lamp1of the invention of the fourth embodiment, wherein the constitution is the same as that of the filament lamp1of the invention of the fourth embodiment except that the light emitting tube16and the insulating walls171,172are fused along their full length in the direction of the tube axis. In this filament lamp1, a pair of insulating walls171,172are placed along the inner walls on two sides of the light emitting tube16, with the filaments411to451sandwiched therebetween, and the outer surface of the light emitting tube16is heated in the direction of the tube axis, for example, with a burner by which means the light emitting tube16and the insulating walls171,172are fused in the direction of the tube axis.

The eighth embodiment of this invention is explained usingFIGS. 13 & 14, whereinFIG. 13is a front cross section showing the light-irradiation-type heat-treatment equipment of the invention of this embodiment, andFIG. 14is a plan view showing the first lamp unit and the second lamp unit shown inFIG. 13. The light-irradiation-type heat-treatment equipment100is comprised with the filament lamps1of any of the inventions of the first through the seventh embodiment.

As shown inFIG. 13, this light-irradiation-type heat-treatment equipment100has a chamber102that is divided into a lamp unit accommodation space S1and a heat-treatment space S2by a quartz window101. Heat treatment of a workpiece to be treated105is done by irradiating the workpiece to be treated105, which is located in the heat-treatment space S2, with light that passes through the quartz window101after it is emitted by the first lamp unit103and the second lamp unit104.

The first lamp unit103and the second lamp unit104accommodated in the lamp unit accommodation space S1face each other, and each is constituted with, for example, ten filament lamps1arranged parallel to each other and separated by gaps of a specified size. As shown inFIG. 14, the direction of the tube axes of the filament lamps1that make up the first lamp unit103intersects the direction of the tube axes of the filament lamps1that make up the second lamp unit104. Although two stages of lamp units, as shown inFIG. 9, can be employed, a constitution with only one lamp unit stage is also acceptable.

Reflecting optics106are located above the first lamp unit103. The reflecting optics106, for example, can have a structure of a gold coating on a base material of oxygen-free copper, and the cross section of the reflecting surface has a shape such as a partial circle, a partial ellipse, a partial parabola, or a flat plate. Light that is emitted upward by the first lamp unit103and the second lamp unit104is reflected toward the workpiece to be treated105by the reflecting optics106. In other words, the light emitted by the first lamp unit103and the second lamp unit104is reflected by the reflecting optics106and irradiates the workpiece to be treated105.

Cold air from the cold air unit107is introduced into the lamp unit accommodation space S1through the jets109of the cold air supply nozzles108installed in the chamber102. The cold air introduced into the lamp unit accommodation space S1is blown onto the filament lamps1of the first lamp unit103and the second lamp unit104, thereby cooling the light emitting tubes that make up the filament lamps1. The seal areas of the filament lamps1have a lower resistance to heat than other parts. It is desirable, therefore, that the jets109of the cold air supply nozzles be directed toward the seal areas of the filament lamps1, and that they be constituted to give priority to cooling the seal areas of the filament lamps1.

The cold air that is blown on the filament lamps1and reaches a high temperature by means of heat exchange is exhausted by way of the cold air exhaust port installed in the chamber102. Consideration has been given so that the flow of cold air does not, conversely, heat the filament lamps1after it has reached a high temperature by means of heat exchange. The flow of this cold air is set so that it cools the reflecting optics106at the same time. It is not necessary to set the flow of air to cool the reflecting optics106at the same time, for example, in the event that the reflecting optics are water-cooled by a water cooling mechanism (not shown).

Incidentally, there may be an accumulation of heat in the quartz window101, due to radiant heat from the heated workpiece105. Secondary thermal radiation from the quartz window101that has accumulated heat sometimes has an undesirable effect of heating the workpiece to be treated105. In this case, there may be such problems as redundancy of temperature control of the workpiece to be treated105(e.g., overshoot such that the temperature of the workpiece to be treated105is hotter than the set temperature) or reduced temperature uniformity in the workpiece to be treated105due to the temperature of the quartz window101that has accumulated heat. Moreover, it becomes difficult to increase the rate of cooling of the workpiece to be treated105. To suppress these problems, therefore, it is desirable to install a jet109of a cold air supply nozzle108in the vicinity of the quartz window101, as shown inFIG. 13, and to cool the quartz window101with cold air from the cold air unit107.

Each filament lamp1of the first lamp unit103is supported by a pair of first fixed stages111,112. The first fixed stages111,112comprise conductive stages113that are formed of conductive material and holding stages114that are formed of an insulating material such as a ceramic. The holding stages114are mounted on the inner wall of the chamber102and hold the conductive stages113. Taking the number of filament lamps1in the first lamp unit103as n1 and the number of filament assemblies per filament lamp1as m1, the number of paired sets of first fixed stages111,112is n1×m1 sets, in the event that power is supplied independently to all of the filament assemblies. Each filament lamp1of the second lamp unit104, on the other hand, is supported by second fixed stages. Like the first fixed stages111,112, the second fixed stages comprise conductive stages and holding stages. Taking the number of filament lamps1in the second lamp unit104as n2 and the number of filament assemblies per filament lamp1as m2, the number of paired sets of second fixed stages is n2×m2 sets, in the event that power is supplied independently to all of the filament assemblies.

Pairs of electrical power-supply ports116,117are installed in the chamber102and connected to power feed wires from the power supply of the power source115. A single pair of power-supply ports116,117is shown inFIG. 13, but the number of power-supply ports is determined by the number of filament lamps1and the number of filament assemblies in each filament lamp1. InFIG. 13, the power-supply ports116,117are electrically connected to the conductive stages113of the first lamp fixed stages111,112. The conductive stages113of the first lamp fixed stages111,112, for example, are electrically connected to the external leads. By means of such a constitution, it becomes possible to feed power from the power supply in the power source115to a filament assembly of one filament lamp in the first lamp unit103. The other filament assemblies of that filament lamp1, the filaments of the other filament lamps1in the first lamp unit103, and the filaments of each filament lamp1in the second lamp unit104are similarly connected electrically to other paired power-supply ports.

Moreover, a treatment stage118to which the workpiece to be treated105is fixed is installed in the heat-treatment space S2. If the workpiece to be treated105, for example, is a semiconductor wafer, the treatment stage118is a thin, ring-shaped plate of a high-melting-point metal such as molybdenum, tungsten, or tantalum or a ceramic, such as silicon carbide (SiC), or quartz or silicon (Si). Preferably it has a guard-ring structure formed with steps to hold the semiconductor wafer within a round opening. The semiconductor wafer that is the workpiece to be treated105is placed so that the semiconductor wafer is held in the round opening of the round guard ring and supported by the steps. The treatment stage118is itself heated by light irradiation and provides supplementary heat to the outer edge of the semiconductor wafer that faces it. Advantageously, this compensates for the heat radiated from the outer edge of the semiconductor wafer. By this means, temperature drops at the periphery of the semiconductor wafer due to heat radiated from the outer edge of the semiconductor wafer can be suppressed.

On the reverse side from the light-irradiation side of the workpiece to be treated105that is set in the treatment stage118, there are temperature measurement areas119in contact with or close to the workpiece to be treated105. The temperature measurement areas119monitor the temperature distribution of the workpiece to be treated105, wherein their number and placement depends on the dimensions of the workpiece to be treated105. For example, thermocouples or radiant heat thermometers can be used as the temperature measurement areas119. The temperature information monitored by the temperature measurement areas119is transmitted to the thermometer120. On the basis of the temperature information transmitted by the temperature measurement areas119, the thermometer120calculates the temperatures at the points measured by each temperature measurement area119and sends the calculated temperature information to the main controller122by way of the temperature controller121. Based on the temperature information for the points measured on the workpiece to be treated105, the main controller122sends the temperature controller121commands to make designated temperatures on the workpiece to be uniformly treated105. On the basis of these commands, the temperature controller121controls the power supplied from the power source115to each filament assembly of the filament lamps1. For example, if the main controller121receives temperature information from the temperature controller121to the effect that the temperature of a certain measured point is lower than the specified temperature, it sends the temperature controller121a command to increase the amount of power fed to the filament assembly next to the measured point, so that the light emitted from the light emitting area of that filament assembly will increase. Based on the command transmitted from the main controller122, the temperature controller121will increase the power supplied from the power source115to the power-supply ports116,117connected to that filament assembly.

While the filament lamps1in the first and second lamp units102,103are lit, the main controller122sends commands to the cold air unit107so that the light emitting tubes and the quartz window101will not reach a high temperature. Depending on the type of heat treatment, moreover, a process gas unit123that introduces and exhausts process gases can be connected to the heat-treatment space S2. For example, if a hot oxidation process is to be conducted, a process gas unit123is connected to the heat-treatment space S2to introduce and exhaust oxygen gas and a purge gas (e.g., such as nitrogen gas) to purge the heat-treatment space S2. The process gases and purge gases from the process gas unit123are introduced into the heat-treatment space S2from the jet125of the gas supply nozzle124installed in the chamber102and they are exhausted through the exhaust port126.

Using the light-irradiation-type heat-treatment equipment100described above, it is possible to achieve the following effects. Within the filament lamps1mounted in the lamp units103,104that are the light source of the light-irradiation-type heat-treatment equipment100, the light emitting areas comprise the filament assemblies and insulating walls shown in the first through the seventh embodiments above, and the power supplied to each filament can be controlled independently, so that setting the light-intensity distribution can be regulated even in the tube axis direction of the light emitting tubes. Therefore, the treatment intensity distribution on the surface of the workpiece to be treated105can also be set with high precision in two dimensions. For example, for a small special region (such as special region1inFIG. 14) that is shorter than the light emission length of the filament lamps used in the light source of the light-irradiation-type heat-treatment equipment of the related art, it is possible to set the irradiation intensity for a special region (e.g., region1) and limit it to that special region (e.g., region1). That is, it is possible to set the distribution of illuminance to suit the respective characteristics of both the special region (e.g., region1) and the other region (e.g., region2inFIG. 10). Therefore, it is possible to control the temperatures of the special region and the other region (e.g., region2) so that they are uniform. Similarly, it is possible to suppress the occurrence of localized temperature distributions on the workpiece to be treated105, and to obtain a uniform temperature distribution across the full workpiece to be treated105.

Moreover, because filament lamps1which have very fine and closely spaced filament leads in the light emitting tubes are used in the light-irradiation-type heat-treatment equipment of this invention, the influence of the gaps between filaments, which do not emit light, can be reduced. Further, the space holding the lamp units103,104that comprise multiple tubular filament lamps1can be kept small in height for the light-irradiation-type heat-treatment equipment100, and so the size of the light-irradiation-type heat-treatment equipment100can be reduced.

By means of the filament lamps1that are mounted in this light-irradiation-type heat-treatment device100, as was explained in connection with the inventions of the first embodiment through the seventh embodiment, the insulating wall located inside each filaments supports the leads of that filament so that it does not short circuit with the leads of other filaments. Even in a constitution with multiple filament assemblies within a light emitting tube, therefore, leads are not located outside the filaments, and so it is easy to obtain the desired light-distribution of illuminance with the light emitted by the filaments and not blocked by the leads, while assuring insulation between the leads.

Although the light-irradiation-type heat-treatment equipment of this invention has been described in terms of lamp units103,104constituted with multiple, parallel filament lamps1employed as the light source, in further embodiments a light source constituted with a single filament lamp1can be employed, as will be appreciated by those skilled in the relevant art(s).

Although the workpieces to receive heat treatment in the light-irradiation-type heat-treatment equipment of this invention are described in terms of semiconductor wafers, in further embodiments the equipment can be applied to crystalline silicon substrates or glass or ceramic substrates for solar cell panels, or glass substrates for liquid-crystal displays, etc., as will be appreciated by those skilled in the relevant art(s).

For example, rectangular substrates of various materials are often used for solar cell panels, and most of the light-irradiation-type heat-treatment devices used for heat treatment of such workpieces is constituted to move the rectangular substrate horizontally and to provide heat treatment by irradiation with a band of light, either by means of a single filament lamp that is placed so that the tube axis extends in a direction perpendicular to the direction of substrate movement, or by means of multiple filament lamps arrayed to provide heat treatment by irradiating with a band of light. Using a filament lamp1having four or more filament assemblies in such cases makes it possible, while compensating for the temperature drop in the two areas parallel to the direction of substrate motion (e.g., at the two ends of the band), to regulate the distribution of illuminance on the center of the substrate (e.g., at the center of the band), and thus to assure more precise temperature control.