JP7177619B2 - Heat treatment equipment - Google Patents

Description

The present invention relates to a heat treatment apparatus for heating a thin precision electronic substrate such as a semiconductor wafer (hereinafter simply referred to as "substrate") by light irradiation or the like.

Flash lamp annealing (FLA), which heats a semiconductor wafer in an extremely short time, has attracted attention in the manufacturing process of semiconductor devices. Flash lamp annealing uses a xenon flash lamp (hereinafter simply referred to as a "flash lamp" to mean a xenon flash lamp) to irradiate the surface of the semiconductor wafer with flash light, so that only the surface of the semiconductor wafer is extremely annealed. It is a heat treatment technology that raises the temperature in a short time (several milliseconds or less).

The radiation spectral distribution of the xenon flash lamp is from the ultraviolet region to the near-infrared region, the wavelength is shorter than that of the conventional halogen lamp, and it almost matches the fundamental absorption band of the silicon semiconductor wafer. Therefore, when the semiconductor wafer is irradiated with flash light from the xenon flash lamp, it is possible to rapidly raise the temperature of the semiconductor wafer with little transmitted light. In addition, it has been found that only the vicinity of the surface of the semiconductor wafer can be selectively heated by flash light irradiation for a very short period of several milliseconds or less.

Such flash lamp annealing is used in processes that require very short heating times, such as activation of impurities typically implanted in semiconductor wafers. By irradiating the surface of a semiconductor wafer into which impurities have been implanted by ion implantation with flash light from a flash lamp, the surface of the semiconductor wafer can be heated to the activation temperature for a very short period of time, and the impurities can be deeply diffused. Therefore, only impurity activation can be performed without causing the activation of the impurities.

On the other hand, semiconductor devices are typically formed using silicon, but in recent years, when the limits of miniaturization are approaching, there are many attempts to form semiconductor devices using materials that replace silicon. Semiconductors such as germanium and gallium arsenide (GaAs) have higher mobility than silicon, and by forming transistors using these materials, it is possible to fabricate semiconductor devices with higher performance than silicon. For example, Patent Document 1 discloses that a gallium arsenide semiconductor thin film containing tin, germanium, lead, or the like is subjected to flash lamp annealing to obtain a semiconductor thin film with high carrier mobility and high quality. ing.

JP-A-2002-252174

However, it has been found that when a gallium arsenide semiconductor is heated to 400° C. or higher, arsenic (As) is released from the semiconductor thin film by outward diffusion. Even in flash lamp annealing, the semiconductor thin film reaches a temperature range of 400° C. or higher, albeit for a short period of time, so there is concern about the release of arsenic due to outward diffusion. Arsenic is known to be harmful even in trace amounts.

Therefore, it is required not to discharge the arsenic released during heating from the flash lamp annealing apparatus to the outside. In general, a scrubber or an abatement device is connected to the factory exhaust as a measure to prevent arsenic and other harmful substances from being diffused into the atmosphere. However, it is impractical from a cost performance and footprint standpoint to incorporate such scrubbers and abatement devices into a flash lamp annealer.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat treatment apparatus capable of preventing harmful substances from being discharged to the outside with a simple structure.

In order to solve the above-described problems, the invention of claim 1 provides a heat treatment apparatus for heating a substrate, comprising: a chamber for accommodating a substrate; a heat source for heating the substrate accommodated in the chamber; and a trap part provided in the exhaust path for trapping substances contained in the atmosphere, wherein the trap part cools the airflow passing through the housing inside the housing The trap further includes a trap plate inside the housing against which the airflow cooled by the cooling unit collides, and the trap unit cools the airflow by the cooling unit. It is characterized by further comprising an accommodation portion inside the housing for accommodating a collection substrate to which the deposited substance adheres .

According to a second aspect of the invention, in the heat treatment apparatus according to the first aspect of the invention, the heating source includes a lamp for irradiating the substrate with light to heat the substrate.

Further, the invention of claim 3 is characterized in that, in the heat treatment apparatus according to the invention of claim 1 or claim 2, the substance is arsenic.

According to the invention of claims 1 to 3 , the trap section provided in the exhaust path is provided with a cooling section inside the housing for cooling the airflow passing through the housing. can be precipitated and captured as a solid, and harmful substances can be prevented from being discharged to the outside with a simple configuration. In addition, since the trap section has a trap plate against which the airflow cooled by the cooling section collides, it is possible to more reliably trap harmful substances. In addition, since the trap section includes a storage section that stores the collection substrate to which the substance deposited by the cooling section cools the airflow, it is possible to confirm the capture of the hazardous substance by analyzing the collection substrate. can.

1 is a vertical cross-sectional view showing the configuration of a heat treatment apparatus according to the present invention; FIG. It is a perspective view which shows the whole external appearance of a holding|maintenance part. 4 is a plan view of the susceptor; FIG. 4 is a cross-sectional view of the susceptor; FIG. It is a top view of a transfer mechanism. It is a side view of a transfer mechanism. FIG. 4 is a plan view showing the arrangement of a plurality of halogen lamps; It is a perspective view which shows the structure of a trap box. It is a front view of a trap box. It is a top view of a trap box.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a vertical cross-sectional view showing the configuration of a heat treatment apparatus 1 according to the present invention. The heat treatment apparatus 1 of FIG. 1 is a flash lamp annealing apparatus that heats a disk-shaped semiconductor wafer W as a substrate by irradiating the semiconductor wafer W with flash light. Although the size of the semiconductor wafer W to be processed is not particularly limited, it is, for example, φ300 mm or φ450 mm (φ300 mm in this embodiment). A semiconductor thin film of gallium arsenide is formed on the semiconductor wafer W before it is carried into the heat treatment apparatus 1, and the impurities injected into the gallium arsenide are activated by heat treatment by the heat treatment apparatus 1. FIG. In addition, in FIG. 1 and subsequent figures, the dimensions and numbers of each part are exaggerated or simplified as necessary for easy understanding.

The heat treatment apparatus 1 includes a chamber 6 containing a semiconductor wafer W, a flash heating section 5 containing a plurality of flash lamps FL, and a halogen heating section 4 containing a plurality of halogen lamps HL. A flash heating section 5 is provided on the upper side of the chamber 6, and a halogen heating section 4 is provided on the lower side. The heat treatment apparatus 1 also includes a holding unit 7 that holds the semiconductor wafer W in a horizontal posture inside the chamber 6, a transfer mechanism 10 that transfers the semiconductor wafer W between the holding unit 7 and the outside of the apparatus, Prepare. The heat treatment apparatus 1 also includes a trap box 90 that removes arsenic, which is a harmful substance, from the gas exhausted from the chamber 6 . Further, the heat treatment apparatus 1 includes a control section 3 that controls each operation mechanism provided in the halogen heating section 4, the flash heating section 5, and the chamber 6 to perform the heat treatment of the semiconductor wafer W. As shown in FIG.

The chamber 6 is configured by mounting chamber windows made of quartz on the upper and lower sides of a cylindrical chamber side portion 61 . The chamber side part 61 has a substantially cylindrical shape with upper and lower openings, the upper opening being closed by an upper chamber window 63, and the lower opening being closed by a lower chamber window 64. ing. The upper chamber window 63 forming the ceiling of the chamber 6 is a disc-shaped member made of quartz and functions as a quartz window through which the flash light emitted from the flash heating unit 5 is transmitted into the chamber 6 . A lower chamber window 64 forming the floor of the chamber 6 is also a disk-shaped member made of quartz and functions as a quartz window through which the light from the halogen heating unit 4 is transmitted into the chamber 6 .

A reflecting ring 68 is attached to the upper portion of the inner wall surface of the chamber side portion 61, and a reflecting ring 69 is attached to the lower portion thereof. Both the reflecting rings 68 and 69 are formed in an annular shape. The upper reflector ring 68 is attached by fitting from the upper side of the chamber side 61 . On the other hand, the lower reflecting ring 69 is attached by fitting from the lower side of the chamber side portion 61 and fastening with screws (not shown). That is, both the reflecting rings 68 and 69 are detachably attached to the chamber side portion 61 . A space inside the chamber 6 , that is, a space surrounded by the upper chamber window 63 , the lower chamber window 64 , the chamber side portion 61 and the reflective rings 68 and 69 is defined as a thermal processing space 65 .

A concave portion 62 is formed in the inner wall surface of the chamber 6 by attaching the reflecting rings 68 and 69 to the chamber side portion 61 . That is, the recess 62 is formed by the central portion of the inner wall surface of the chamber side portion 61 where the reflecting rings 68 and 69 are not attached, the lower end surface of the reflecting ring 68, and the upper end surface of the reflecting ring 69. . The concave portion 62 is formed in an annular shape along the horizontal direction on the inner wall surface of the chamber 6 and surrounds the holding portion 7 that holds the semiconductor wafer W. As shown in FIG. The chamber side portion 61 and the reflecting rings 68, 69 are made of a metallic material (for example, stainless steel) having excellent strength and heat resistance.

A transfer opening (furnace port) 66 for transferring the semiconductor wafer W into and out of the chamber 6 is formed in the chamber side portion 61 . The transport opening 66 can be opened and closed by a gate valve 185 . The conveying opening 66 is communicated with the outer peripheral surface of the recess 62 . Therefore, when the gate valve 185 opens the transfer opening 66 , the semiconductor wafer W can be transferred from the transfer opening 66 to the heat treatment space 65 through the recess 62 and transferred from the heat treatment space 65 . It can be performed. Further, when the gate valve 185 closes the transfer opening 66, the heat treatment space 65 in the chamber 6 becomes a closed space.

Further, the chamber side portion 61 is provided with a through hole 61a. A radiation thermometer 20 is attached to a portion of the outer wall surface of the chamber side portion 61 where the through hole 61a is provided. The through hole 61 a is a cylindrical hole for guiding infrared light emitted from the lower surface of a semiconductor wafer W held by a susceptor 74 to be described later to the radiation thermometer 20 . The through-hole 61 a is inclined with respect to the horizontal direction so that the axis in the through-hole direction intersects the main surface of the semiconductor wafer W held by the susceptor 74 . A transparent window 21 made of a barium fluoride material that transmits infrared light in a wavelength range measurable by the radiation thermometer 20 is attached to the end of the through hole 61 a facing the heat treatment space 65 .

A gas supply hole 81 for supplying a processing gas to the heat treatment space 65 is formed in the upper portion of the inner wall of the chamber 6 . The gas supply hole 81 is formed above the recess 62 and may be provided in the reflection ring 68 . The gas supply hole 81 is communicated with a gas supply pipe 83 through an annular buffer space 82 formed inside the side wall of the chamber 6 . The gas supply pipe 83 is connected to a process gas supply source 85 . An air supply valve 84 is inserted in the middle of the path of the gas supply pipe 83 . When the air supply valve 84 is opened, process gas is delivered from the process gas supply 85 to the buffer space 82 . The processing gas that has flowed into the buffer space 82 flows so as to expand in the buffer space 82 , which has a smaller fluid resistance than the gas supply hole 81 , and is supplied from the gas supply hole 81 into the heat treatment space 65 . As the processing gas, for example, an inert gas such as nitrogen (N ₂ ), a reactive gas such as hydrogen (H ₂ ) or ammonia (NH ₃ ), or a mixed gas thereof can be used (this Nitrogen gas in embodiments).

On the other hand, a gas exhaust hole 86 for exhausting the gas in the heat treatment space 65 is formed in the lower part of the inner wall of the chamber 6 . The gas exhaust hole 86 is formed below the recess 62 and may be provided in the reflecting ring 69 . The gas exhaust hole 86 is communicated with a gas exhaust pipe 88 through an annular buffer space 87 formed inside the side wall of the chamber 6 . The gas exhaust pipe 88 is connected to the exhaust section 190 . An exhaust valve 89 and a trap box 90 are interposed along the path of the gas exhaust pipe 88 . When the exhaust valve 89 is opened, the gas in the heat treatment space 65 is exhausted from the gas exhaust hole 86 to the gas exhaust pipe 88 through the buffer space 87 . A plurality of gas supply holes 81 and gas exhaust holes 86 may be provided along the circumferential direction of the chamber 6, or may be slit-shaped.

As the exhaust unit 190, the exhaust utility of the factory where the vacuum pump and the heat treatment apparatus 1 are installed can be used. A vacuum pump is employed as the exhaust unit 190, and when the air supply valve 84 is closed and the atmosphere of the heat treatment space 65, which is a closed space, is exhausted without supplying any gas from the gas supply hole 81, the inside of the chamber 6 is brought into a vacuum atmosphere. can be reduced to Further, even if a vacuum pump is not used as the exhaust part 190, the inside of the chamber 6 can be decompressed to a pressure lower than the atmospheric pressure by performing exhaust without supplying gas from the gas supply hole 81. .

FIG. 8 is a perspective view showing the configuration of the trap box 90. As shown in FIG. 9 is a front view of the trap box 90, and FIG. 10 is a plan view of the trap box 90. As shown in FIG. 8 to 10, in order to clarify their directional relationship, an XYZ orthogonal coordinate system is attached in which the Z-axis direction is the vertical direction and the XY plane is the horizontal plane.

The trap box 90 is provided in the middle of the route of the gas exhaust pipe 88 . The installation position of the trap box 90 is not particularly limited, but it is preferably installed as close to the gas exhaust hole 86 of the chamber 6 as possible in the middle of the path of the gas exhaust pipe 88 .

The trap box 90 includes a radiator 92 , a trap plate 95 and a wafer storage section 96 as main components inside a housing 91 . The housing 91 is a hollow rectangular parallelepiped box. The housing 91 is provided with an air supply port 97 for taking in gas and an exhaust port 98 for discharging the internal gas. The air supply port 97 and the exhaust port 98 are connected to a gas exhaust pipe 88 that guides gas discharged from the chamber 6 .

The radiator 92 is provided over the entire cross section (YZ cross section) of the housing 91 so as to separate the internal space of the housing 91 . The radiator 92 includes a plurality of cooling pipes 93, a tank (not shown), and a circulation pump. The plurality of cooling pipes 93 are arranged side by side in parallel at predetermined intervals. Each of the plurality of cooling pipes 93 is made of a material with excellent thermal conductivity, such as aluminum. A cooling liquid (for example, cooling water) stored in a tank and adjusted to a predetermined temperature is configured to flow and circulate through a plurality of cooling pipes 93 by a circulation pump. The gas passing between the plurality of cooling pipes 93 is cooled by the cooling pipes 93 through which the coolant flows. Since the radiator 92 is provided on the entire cross section of the housing 91 , it cools the entire airflow passing through the housing 91 . In order to improve the cooling efficiency of the radiator 92, the cooling pipes 93 may have a meandering shape with a large surface area, or a plurality of cooling pipes 93 may be arranged in a grid.

The trap plate 95 is a plate-like member provided parallel to the radiator 92 inside the housing 91 . As shown in FIGS. 8 and 9, the trap plate 95 is provided so as to shield the upper portion of the cross section (YZ cross section) of the housing 91 . Therefore, in the cross section of the housing 91 in which the trap plate 95 is installed, the bottom of the trap plate 95 is open. Although the material of the trap plate 95 is not particularly limited, vinyl chloride resin, for example, can be used.

The radiator 92 and the trap plate 95 are detachably attached to the housing 91 . Therefore, it is possible to replace the radiator 92 and the trap plate 95 as required.

The wafer housing part 96 is installed below the trap plate 95 inside the housing 91 . The wafer accommodation part 96 mounts the measurement wafer MW in a horizontal posture below the trap plate 95 . In other words, the wafer accommodation section 96 mounts the measurement wafer MW perpendicularly to the trap plate 95 . The measurement wafer MW is a silicon substrate having the same shape and size as a general semiconductor wafer W. However, the measurement wafer MW is not subjected to pattern formation or film formation.

FIG. 2 is a perspective view showing the overall appearance of the holding portion 7. As shown in FIG. The holding portion 7 includes a base ring 71 , a connecting portion 72 and a susceptor 74 . The base ring 71, the connecting portion 72 and the susceptor 74 are all made of quartz. That is, the entire holding portion 7 is made of quartz.

The base ring 71 is an arc-shaped quartz member that is partly missing from an annular ring. This missing portion is provided to prevent interference between the transfer arm 11 of the transfer mechanism 10 and the base ring 71, which will be described later. The base ring 71 is supported by the wall surface of the chamber 6 by being placed on the bottom surface of the recess 62 (see FIG. 1). A plurality of connecting portions 72 (four in this embodiment) are erected on the upper surface of the base ring 71 along the circumferential direction of the annular shape. The connecting portion 72 is also a quartz member and is fixed to the base ring 71 by welding.

The susceptor 74 is supported by four connecting portions 72 provided on the base ring 71 . 3 is a plan view of the susceptor 74. FIG. 4 is a cross-sectional view of the susceptor 74. FIG. The susceptor 74 comprises a retaining plate 75 , a guide ring 76 and a plurality of substrate support pins 77 . The holding plate 75 is a substantially circular flat member made of quartz. The diameter of the holding plate 75 is larger than the diameter of the semiconductor wafer W. That is, the holding plate 75 has a planar size larger than the semiconductor wafer W. As shown in FIG.

A guide ring 76 is installed on the peripheral edge of the upper surface of the holding plate 75 . The guide ring 76 is an annular member having an inner diameter larger than the diameter of the semiconductor wafer W. As shown in FIG. For example, when the diameter of the semiconductor wafer W is φ300 mm, the inner diameter of the guide ring 76 is φ320 mm. The inner circumference of the guide ring 76 is tapered such that it widens upward from the holding plate 75 . The guide ring 76 is made of quartz similar to the holding plate 75 . The guide ring 76 may be welded to the upper surface of the holding plate 75, or may be fixed to the holding plate 75 by a separately processed pin or the like. Alternatively, the holding plate 75 and the guide ring 76 may be processed as an integral member.

A region of the upper surface of the holding plate 75 inside the guide ring 76 serves as a planar holding surface 75a for holding the semiconductor wafer W. As shown in FIG. A plurality of substrate support pins 77 are erected on the holding surface 75 a of the holding plate 75 . In this embodiment, a total of 12 substrate support pins 77 are erected at 30° intervals along a circle concentric with the outer circumference of the holding surface 75a (the inner circumference of the guide ring 76). The diameter of the circle in which the 12 substrate support pins 77 are arranged (the distance between the opposing substrate support pins 77) is smaller than the diameter of the semiconductor wafer W. 270 mm in shape). Each substrate support pin 77 is made of quartz. The plurality of substrate support pins 77 may be provided on the upper surface of the holding plate 75 by welding, or may be processed integrally with the holding plate 75 .

Returning to FIG. 2, the four connecting portions 72 erected on the base ring 71 and the peripheral portion of the holding plate 75 of the susceptor 74 are fixed by welding. That is, the susceptor 74 and the base ring 71 are fixedly connected by the connecting portion 72 . The holder 7 is attached to the chamber 6 by supporting the base ring 71 of the holder 7 on the wall surface of the chamber 6 . When the holding portion 7 is attached to the chamber 6, the holding plate 75 of the susceptor 74 assumes a horizontal posture (a posture in which the normal line coincides with the vertical direction). That is, the holding surface 75a of the holding plate 75 becomes a horizontal surface.

The semiconductor wafer W carried into the chamber 6 is placed and held in a horizontal posture on the susceptor 74 of the holding part 7 mounted in the chamber 6 . At this time, the semiconductor wafer W is held by the susceptor 74 while being supported by twelve substrate supporting pins 77 erected on the holding plate 75 . More strictly, the upper ends of the 12 substrate support pins 77 are in contact with the lower surface of the semiconductor wafer W to support the semiconductor wafer W. As shown in FIG. Since the height of the 12 substrate support pins 77 (the distance from the upper end of the substrate support pin 77 to the holding surface 75a of the holding plate 75) is uniform, the semiconductor wafer W can be held in a horizontal posture by the 12 substrate support pins 77. can support.

Also, the semiconductor wafer W is supported by a plurality of substrate support pins 77 at a predetermined distance from the holding surface 75a of the holding plate 75. As shown in FIG. The thickness of the guide ring 76 is greater than the height of the board support pins 77 . Accordingly, the guide ring 76 prevents the semiconductor wafer W supported by the plurality of substrate support pins 77 from being displaced in the horizontal direction.

Further, as shown in FIGS. 2 and 3, the holding plate 75 of the susceptor 74 is formed with an opening 78 penetrating vertically. The opening 78 is provided so that the radiation thermometer 20 receives radiation light (infrared light) emitted from the lower surface of the semiconductor wafer W. As shown in FIG. That is, the radiation thermometer 20 receives light emitted from the lower surface of the semiconductor wafer W through the transparent window 21 mounted in the opening 78 and the through hole 61a of the chamber side portion 61, and measures the temperature of the semiconductor wafer W. Measure. Further, the holding plate 75 of the susceptor 74 is formed with four through holes 79 through which the lift pins 12 of the transfer mechanism 10 (to be described later) penetrate to transfer the semiconductor wafer W. As shown in FIG.

FIG. 5 is a plan view of the transfer mechanism 10. FIG. 6 is a side view of the transfer mechanism 10. FIG. The transfer mechanism 10 includes two transfer arms 11 . The transfer arm 11 has an arc shape along the generally annular concave portion 62 . Two lift pins 12 are erected on each transfer arm 11 . The transfer arm 11 and lift pins 12 are made of quartz. Each transfer arm 11 is rotatable by a horizontal movement mechanism 13 . The horizontal movement mechanism 13 moves the pair of transfer arms 11 to the transfer operation position (solid line position in FIG. It is horizontally moved to and from the retracted position (the two-dot chain line position in FIG. 5) that does not overlap in plan view. As the horizontal movement mechanism 13, each transfer arm 11 may be rotated by an individual motor. It may be something that moves.

Also, the pair of transfer arms 11 is vertically moved together with the horizontal movement mechanism 13 by the lifting mechanism 14 . When the lifting mechanism 14 raises the pair of transfer arms 11 to the transfer operation position, a total of four lift pins 12 pass through the through holes 79 (see FIGS. 2 and 3) drilled in the susceptor 74, and the lift pins 12 protrudes from the upper surface of the susceptor 74 . On the other hand, when the lifting mechanism 14 lowers the pair of transfer arms 11 to the transfer operation position and removes the lift pins 12 from the through-holes 79, the horizontal movement mechanism 13 moves the pair of transfer arms 11 so as to open them. The transfer arm 11 moves to the retracted position. The retracted position of the pair of transfer arms 11 is directly above the base ring 71 of the holding section 7 . Since the base ring 71 is placed on the bottom surface of the recess 62 , the retracted position of the transfer arm 11 is inside the recess 62 . An exhaust mechanism (not shown) is also provided in the vicinity of the portion where the drive section (horizontal movement mechanism 13 and lifting mechanism 14) of the transfer mechanism 10 is provided, and the atmosphere around the drive section of the transfer mechanism 10 is is discharged to the outside of the chamber 6.

Returning to FIG. 1, the flash heating unit 5 provided above the chamber 6 includes a light source composed of a plurality of (30 in this embodiment) xenon flash lamps FL inside a housing 51, and a lamp above the light source. and a reflector 52 provided to cover the . A lamp light emission window 53 is attached to the bottom of the housing 51 of the flash heating unit 5 . The lamp light emission window 53 forming the floor of the flash heating unit 5 is a plate-shaped quartz window made of quartz. By installing the flash heating unit 5 above the chamber 6 , the lamp light emission window 53 faces the upper chamber window 63 . The flash lamp FL irradiates the heat treatment space 65 with flash light from above the chamber 6 through the lamp light emission window 53 and the upper chamber window 63 .

Each of the plurality of flash lamps FL is a rod-shaped lamp having an elongated cylindrical shape, and the longitudinal direction of each flash lamp FL is along the main surface of the semiconductor wafer W held by the holding portion 7 (that is, along the horizontal direction). They are arranged in a plane so as to be parallel to each other. Therefore, the plane formed by the arrangement of the flash lamps FL is also a horizontal plane. The area in which the plurality of flash lamps FL are arranged is larger than the planar size of the semiconductor wafer W. As shown in FIG.

The xenon flash lamp FL is composed of a rod-shaped glass tube (discharge tube) in which xenon gas is filled and an anode and a cathode connected to a condenser are arranged at both ends of the tube (discharge tube), and an outer peripheral surface of the glass tube is provided. and a trigger electrode. Since xenon gas is an electrical insulator, electricity does not flow in the glass tube under normal conditions even if electric charges are accumulated in the capacitor. However, when a high voltage is applied to the trigger electrode to break down the insulation, the electricity stored in the capacitor instantly flows into the glass tube, and the xenon atoms or molecules are excited at that time to emit light. In such a xenon flash lamp FL, the electrostatic energy previously stored in the capacitor is converted into an extremely short light pulse of 0.1 millisecond to 100 milliseconds. It has the characteristic of being able to irradiate extremely strong light compared to the light source. That is, the flash lamp FL is a pulsed light emitting lamp that instantaneously emits light in an extremely short time of less than 1 second. The light emission time of the flash lamp FL can be adjusted by the coil constant of the lamp power source that supplies power to the flash lamp FL.

Moreover, the reflector 52 is provided above the plurality of flash lamps FL so as to cover them as a whole. The basic function of the reflector 52 is to reflect the flash light emitted from the plurality of flash lamps FL to the heat treatment space 65 side. The reflector 52 is made of an aluminum alloy plate, and its surface (the surface facing the flash lamp FL) is roughened by blasting.

The halogen heating unit 4 provided below the chamber 6 incorporates a plurality of (40 in this embodiment) halogen lamps HL inside a housing 41 . The halogen heating unit 4 heats the semiconductor wafer W by irradiating the heat treatment space 65 with light from the lower side of the chamber 6 through the lower chamber window 64 using a plurality of halogen lamps HL.

FIG. 7 is a plan view showing the arrangement of multiple halogen lamps HL. The 40 halogen lamps HL are arranged in two upper and lower stages. Twenty halogen lamps HL are arranged in the upper stage near the holding part 7, and twenty halogen lamps HL are arranged in the lower stage farther from the holding part 7 than the upper stage. Each halogen lamp HL is a rod-shaped lamp having an elongated cylindrical shape. The 20 halogen lamps HL in both the upper stage and the lower stage are arranged so that their longitudinal directions are parallel to each other along the main surface of the semiconductor wafer W held by the holding portion 7 (that is, along the horizontal direction). there is Therefore, the plane formed by the arrangement of the halogen lamps HL in both the upper stage and the lower stage is a horizontal plane.

Further, as shown in FIG. 7, the arrangement density of the halogen lamps HL in both the upper and lower stages is higher in the region facing the peripheral portion than in the region facing the central portion of the semiconductor wafer W held by the holding portion 7. there is That is, in both the upper and lower stages, the arrangement pitch of the halogen lamps HL is shorter in the peripheral portion than in the central portion of the lamp arrangement. Therefore, it is possible to irradiate a larger amount of light to the peripheral portion of the semiconductor wafer W, which tends to cause a temperature drop during heating by light irradiation from the halogen heating unit 4 .

A group of halogen lamps HL in the upper stage and a group of halogen lamps HL in the lower stage are arranged so as to cross each other in a grid pattern. That is, a total of 40 halogen lamps HL are arranged such that the longitudinal direction of the 20 halogen lamps HL arranged in the upper stage and the longitudinal direction of the 20 halogen lamps HL arranged in the lower stage are perpendicular to each other. there is

The halogen lamp HL is a filament-type light source that emits light by turning the filament incandescent by energizing the filament arranged inside the glass tube. Inside the glass tube, a gas obtained by introducing a small amount of a halogen element (iodine, bromine, etc.) into an inert gas such as nitrogen or argon is sealed. By introducing a halogen element, it becomes possible to set the temperature of the filament to a high temperature while suppressing breakage of the filament. Therefore, the halogen lamp HL has characteristics that it has a longer life than a normal incandescent lamp and can continuously irradiate strong light. That is, the halogen lamp HL is a continuous lighting lamp that continuously emits light for at least one second. Further, since the halogen lamp HL is a rod-shaped lamp, it has a long life. By arranging the halogen lamp HL along the horizontal direction, the radiation efficiency to the semiconductor wafer W above is excellent.

In addition, a reflector 43 is provided below the two-stage halogen lamp HL in the housing 41 of the halogen heating unit 4 (FIG. 1). The reflector 43 reflects the light emitted from the plurality of halogen lamps HL to the heat treatment space 65 side.

The control unit 3 controls the various operating mechanisms provided in the heat treatment apparatus 1 . The hardware configuration of the control unit 3 is the same as that of a general computer. That is, the control unit 3 includes a CPU that is a circuit that performs various arithmetic processing, a ROM that is a read-only memory that stores basic programs, a RAM that is a readable and writable memory that stores various information, and control software and data. Equipped with a magnetic disk for storage. The processing in the heat treatment apparatus 1 proceeds as the CPU of the control unit 3 executes a predetermined processing program.

In addition to the above configuration, the heat treatment apparatus 1 prevents excessive temperature rise of the halogen heating section 4, the flash heating section 5, and the chamber 6 due to thermal energy generated from the halogen lamps HL and the flash lamps FL during the heat treatment of the semiconductor wafer W. Therefore, it has various cooling structures. For example, the walls of the chamber 6 are provided with water cooling pipes (not shown). The halogen heating unit 4 and the flash heating unit 5 have an air-cooling structure in which heat is exhausted by forming a gas flow inside. Air is also supplied to the gap between the upper chamber window 63 and the lamp light emission window 53 to cool the flash heating part 5 and the upper chamber window 63 .

Next, processing operations in the heat treatment apparatus 1 will be described. First, a heat treatment procedure for the semiconductor wafer W to be processed will be described. The semiconductor wafer W to be processed here is a semiconductor substrate in which a gallium arsenide semiconductor thin film is formed on a silicon base material. Activation of the impurity implanted into the gallium arsenide semiconductor thin film is performed by flash light irradiation heat treatment (annealing) by the heat treatment apparatus 1 . The processing procedure of the semiconductor wafer W described below proceeds as the control unit 3 controls each operation mechanism of the heat treatment apparatus 1 .

First, the air supply valve 84 is opened and the exhaust valve 89 is opened to start supplying and exhausting air to and from the chamber 6 . When the gas supply valve 84 is opened, nitrogen gas is supplied from the gas supply hole 81 to the heat treatment space 65 . Further, when the exhaust valve 89 is opened, the gas inside the chamber 6 is exhausted from the gas exhaust hole 86 . As a result, the nitrogen gas supplied from the upper portion of the heat treatment space 65 inside the chamber 6 flows downward and is exhausted from the lower portion of the heat treatment space 65 .

Subsequently, the gate valve 185 is opened to open the transfer opening 66 , and the semiconductor wafer W to be processed is carried into the heat treatment space 65 in the chamber 6 through the transfer opening 66 by the transfer robot outside the apparatus. At this time, there is a risk that the atmosphere outside the apparatus will be involved as the semiconductor wafer W is loaded. Involvement of the external atmosphere can be minimized.

The semiconductor wafer W carried in by the transfer robot advances to a position directly above the holding part 7 and stops there. When the pair of transfer arms 11 of the transfer mechanism 10 moves horizontally from the retracted position to the transfer operation position and rises, the lift pins 12 protrude from the upper surface of the holding plate 75 of the susceptor 74 through the through holes 79 . receives the semiconductor wafer W. At this time, the lift pins 12 rise above the upper ends of the substrate support pins 77 .

After the semiconductor wafer W is placed on the lift pins 12 , the transfer robot leaves the heat treatment space 65 and the transfer opening 66 is closed by the gate valve 185 . As the pair of transfer arms 11 descends, the semiconductor wafer W is transferred from the transfer mechanism 10 to the susceptor 74 of the holding section 7 and held from below in a horizontal posture. The semiconductor wafer W is held by the susceptor 74 while being supported by a plurality of substrate support pins 77 erected on a holding plate 75 . The semiconductor wafer W is held by the holding portion 7 with the surface on which the gallium arsenide semiconductor thin film is formed as the upper surface. A predetermined gap is formed between the back surface (main surface opposite to the front surface) of the semiconductor wafer W supported by the plurality of substrate support pins 77 and the holding surface 75 a of the holding plate 75 . The pair of transfer arms 11 that have descended below the susceptor 74 are retracted by the horizontal movement mechanism 13 to the retracted position, that is, to the inside of the recess 62 .

After the semiconductor wafer W is held from below in a horizontal posture by the susceptor 74 of the holding unit 7 made of quartz, the 40 halogen lamps HL of the halogen heating unit 4 are lit all at once to perform preheating (assist heating). ) is started. Halogen light emitted from the halogen lamps HL passes through the lower chamber window 64 and the susceptor 74 made of quartz, and irradiates the lower surface of the semiconductor wafer W. As shown in FIG. The semiconductor wafer W is preheated by being irradiated with light from the halogen lamp HL, and the temperature rises. Since the transfer arm 11 of the transfer mechanism 10 is retracted inside the recess 62, it does not interfere with the heating by the halogen lamp HL.

The temperature of the semiconductor wafer W is measured by the radiation thermometer 20 when preheating is performed by the halogen lamp HL. Infrared light emitted from the lower surface of the semiconductor wafer W held by the susceptor 74 through the opening 78 is received by the radiation thermometer 20 through the transparent window 21 to measure the temperature of the wafer during heating. The measured temperature of the semiconductor wafer W is transmitted to the controller 3 . The control unit 3 controls the output of the halogen lamps HL while monitoring whether the temperature of the semiconductor wafer W, which is heated by light irradiation from the halogen lamps HL, has reached a predetermined preheating temperature T1. That is, the control unit 3 feedback-controls the output of the halogen lamp HL based on the measured value by the radiation thermometer 20 so that the temperature of the semiconductor wafer W reaches the preheating temperature T1.

After the temperature of the semiconductor wafer W reaches the preheating temperature T1, the controller 3 temporarily maintains the semiconductor wafer W at the preheating temperature T1. Specifically, when the temperature of the semiconductor wafer W measured by the radiation thermometer 20 reaches the preheating temperature T1, the control unit 3 adjusts the output of the halogen lamp HL to bring the temperature of the semiconductor wafer W almost to the preliminary temperature. The heating temperature is maintained at T1.

By performing such preheating using the halogen lamps HL, the temperature of the entire semiconductor wafer W is uniformly raised to the preheating temperature T1. In the stage of preheating by the halogen lamps HL, the temperature of the peripheral portion of the semiconductor wafer W, where heat is more likely to be released, tends to be lower than that of the central portion. The region facing the peripheral portion of the substrate W is higher than the region facing the central portion. For this reason, the amount of light irradiated to the peripheral portion of the semiconductor wafer W, which tends to cause heat dissipation, is increased, and the in-plane temperature distribution of the semiconductor wafer W in the preheating stage can be made uniform.

When a predetermined time has elapsed since the temperature of the semiconductor wafer W reached the preheating temperature T1, the flash lamps FL of the flash heating unit 5 irradiate the surface of the semiconductor wafer W held by the susceptor 74 with flash light. At this time, part of the flash light emitted from the flash lamp FL goes directly into the chamber 6, and the other part is once reflected by the reflector 52 and then goes into the chamber 6. Flash heating of the semiconductor wafer W is effected by irradiation.

Since the flash heating is performed by irradiating flash light (flash light) from the flash lamps FL, the surface temperature of the semiconductor wafer W can be raised in a short time. That is, the flash light emitted from the flash lamp FL has an extremely short irradiation time of about 0.1 millisecond or more and 100 millisecond or less, in which the electrostatic energy previously stored in the capacitor is converted into an extremely short light pulse. A strong flash. Then, the surface temperature of the semiconductor wafer W flash-heated by flash light irradiation from the flash lamps FL instantaneously rises to the processing temperature T2, and after the impurities injected into the semiconductor wafer W are activated, the surface temperature falls rapidly. As described above, in the heat treatment apparatus 1, the surface temperature of the semiconductor wafer W can be raised and lowered in an extremely short time. Therefore, the impurities implanted into the semiconductor wafer W can be activated while suppressing the thermal diffusion of the impurities. can be done. Since the time required for the activation of the impurity is extremely short compared to the time required for the thermal diffusion of the impurity, even in a short time of 0.1 milliseconds to 100 milliseconds in which diffusion does not occur, the activation will not occur. complete.

The halogen lamp HL is extinguished after a predetermined time has elapsed after the flash heating process is finished. As a result, the temperature of the semiconductor wafer W is rapidly lowered from the preheating temperature T1. The temperature of the semiconductor wafer W during cooling is measured by the radiation thermometer 20 and the measurement result is transmitted to the controller 3 . The control unit 3 monitors whether the temperature of the semiconductor wafer W has decreased to a predetermined temperature based on the measurement result of the radiation thermometer 20 . After the temperature of the semiconductor wafer W is lowered to a predetermined level or less, the pair of transfer arms 11 of the transfer mechanism 10 moves horizontally again from the retracted position to the transfer operation position, thereby moving the lift pins 12 to the susceptor. It protrudes from the upper surface of 74 and receives the semiconductor wafer W after heat treatment from the susceptor 74 . Subsequently, the transfer opening 66 closed by the gate valve 185 is opened, the semiconductor wafer W placed on the lift pins 12 is transferred out by the transfer robot outside the apparatus, and the semiconductor wafer W is heat-treated in the heat treatment apparatus 1. is completed.

Incidentally, in this embodiment, the semiconductor wafer W on which the gallium arsenide semiconductor thin film is formed is subjected to heat treatment. Gallium arsenide is known to be released from the semiconductor thin film by outward diffusion when heated to 400° C. or higher. If the preheating temperature T1 is 400° C. or higher, arsenic will be released from the semiconductor wafer W during preheating by the halogen lamp HL. Further, if the processing temperature T2 is 400° C. or higher, arsenic is released from the semiconductor wafer W even during flash heating by the flash lamps FL, albeit for a short period of time. The arsenic released from the semiconductor wafer W exists in the heat treatment space 65 inside the chamber 6 as gas. Even a small amount of arsenic is harmful, and it is necessary to prevent the arsenic released from the semiconductor wafer W from being discharged to the outside of the heat treatment apparatus 1 .

For this reason, the heat treatment apparatus 1 is provided with a trap box 90 . When the exhaust valve 89 is opened, the atmosphere in the chamber 6 containing arsenic is exhausted from the gas exhaust hole 86 to the gas exhaust pipe 88 . The arsenic-containing gas flows through the gas exhaust pipe 88 and into the trap box 90 through the air supply port 97 . As shown in FIG. 9 , the gas that has flowed into the trap box 90 from the air supply port 97 passes through a plurality of cooling pipes 93 of the radiator 92 . The arsenic-containing gas is cooled to room temperature as it passes through the plurality of cooling pipes 93, thereby depositing gaseous arsenic as a solid.

Subsequently, the gas flow cooled by radiator 92 impinges on trap plate 95 . As shown in FIG. 9, the gas flow that collides with the trap plate 95 changes its flow direction toward the lower side of the open trap plate 95 . At this time, solid arsenic that has cooled and precipitated adheres to the trap plate 95 and is captured.

The gas flow directed downward of the trap plate 95 flows to the inner side of the trap box 90 over the open portion below the trap plate 95 . At this time, the gas flow also comes into contact with the surface of the measurement wafer MW placed in the wafer storage unit 96, and part of the precipitated solid arsenic also adheres to the surface of the measurement wafer MW. Also, part of the arsenic captured by the trap plate 95 falls on the surface of the measurement wafer MW.

The gas flow that has passed below the trap plate 95 flows out from the exhaust port 98 to the gas exhaust pipe 88 again and is discharged to the exhaust portion 190 . The arsenic contained in the gas flowing from the air supply port 97 of the trap box 90 is cooled by the radiator 92 and deposited as a solid, and the deposited arsenic adheres to the trap plate 95 and measurement wafer MW and is captured. be done. Therefore, the gas flowing out from the exhaust port 98 of the trap box 90 does not contain harmful arsenic, and the harmless gas is discharged from the exhaust part 190 to the outside of the heat treatment apparatus 1 .

Thus, although arsenic is harmful, it has the property of being precipitated as a solid when cooled to about room temperature. The present invention has been completed by utilizing such characteristics of arsenic, and the harmful arsenic is produced by cooling the gas discharged from the chamber 6 with the radiator 92 to precipitate arsenic as a solid and capture it. are removed. In this embodiment, the arsenic released from the semiconductor wafer W during the heat treatment is recovered and rendered harmless by a trap box 90 having a simple configuration in which a radiator 92 and a trap plate 95 are provided inside the housing 91 . . Therefore, arsenic, which is a harmful substance, can be prevented from being discharged to the outside with a simple structure without incorporating a scrubber, a special removal device, or the like.

Also, the measurement wafer MW placed in the wafer storage unit 96 is taken out, and particles attached to the surface of the measurement wafer MW are analyzed to confirm whether or not arsenic is precipitated and captured. can be done. If arsenic is not detected from the surface of the measurement wafer MW, or if the detected amount of arsenic is remarkably small, it is suspected that the trap box 90 is not sufficiently collecting arsenic.

In addition, since the radiator 92 and the trap plate 95 are detachable, the radiator 92 and the trap plate 95 contaminated by deposited arsenic can be replaced at an appropriate timing. The radiator 92 and trap plate 95 may be replaced periodically, or may be replaced based on contamination conditions.

Although the embodiments of the present invention have been described above, the present invention can be modified in various ways other than those described above without departing from the scope of the invention. For example, in the above-described embodiment, the radiator 92, the trap plate 95, and the wafer housing portion 96 are provided inside the housing 91, but the trap plate 95 and the wafer housing portion 96 are not essential elements, and at least the housing 91 A radiator 92 may be provided inside. If at least the radiator 92 is provided, the gas discharged from the chamber 6 can be cooled to deposit arsenic as a solid, and the arsenic can be captured by the inner wall surface of the housing 91 . Arsenic can also be prevented from being discharged to the outside in this manner. However, it is possible to capture and recover the precipitated arsenic more reliably by providing the trap plate 95 as in the above embodiment.

Further, in the above embodiment, the gas flow is cooled by the radiator 92 having a plurality of cooling pipes 93, but the present invention is not limited to this. You may make it cool.

Further, the heat treatment of the semiconductor wafer W may be performed by setting the inside of the chamber 6 to a reduced pressure atmosphere. Even in this case, the arsenic emitted from the semiconductor wafer W is precipitated and trapped in the trap box 90, thereby obtaining the same effects as in the above embodiment. However, when the inside of the chamber 6 is reduced to a reduced pressure, the inside of the trap box 90 is also reduced to a pressure lower than the atmospheric pressure. Therefore, the material of the trap plate 95 is preferably a metal material that can be used even under reduced pressure.

Further, in the above embodiment, the flash heating unit 5 is provided with 30 flash lamps FL, but the present invention is not limited to this, and the number of flash lamps FL can be any number. . Also, the flash lamp FL is not limited to a xenon flash lamp, and may be a krypton flash lamp. Also, the number of halogen lamps HL provided in the halogen heating unit 4 is not limited to 40, and may be an arbitrary number.

Further, in the above embodiment, the semiconductor wafer W is preheated by using the filament type halogen lamp HL as the continuous lighting lamp that continuously emits light for one second or longer. Preheating may be performed by using a discharge type arc lamp (for example, a xenon arc lamp) as a continuous lighting lamp instead of the halogen lamp HL.

Further, the heat source for heating the semiconductor wafer W is not limited to lamps, and the semiconductor wafer W may be heated by a hot plate equipped with a heater, for example.

Further, substrates to be processed by the heat treatment apparatus 1 are not limited to semiconductor wafers, and may be glass substrates used for flat panel displays such as liquid crystal display devices or substrates for solar cells. The film formed on the substrate is not limited to gallium arsenide, and any film containing arsenic may be used. Furthermore, the technology according to the present invention is suitable for heat treatment of a substrate that emits harmful substances that precipitate as solids when cooled, not just arsenic.

REFERENCE SIGNS LIST 1 heat treatment device 3 control unit 4 halogen heating unit 5 flash heating unit 6 chamber 7 holding unit 10 transfer mechanism 63 upper chamber window 64 lower chamber window 65 heat treatment space 74 susceptor 88 gas exhaust pipe 90 trap box 91 housing 92 radiator 93 Cooling pipe 95 Trap plate 96 Wafer housing portion FL Flash lamp HL Halogen lamp MW Measurement wafer W Semiconductor wafer

Claims (3)

A heat treatment apparatus for heating a substrate,
a chamber containing the substrate;
a heating source that heats the substrate housed in the chamber;
an exhaust path for exhausting the atmosphere in the chamber;
a trap section provided in the exhaust path for trapping substances contained in the atmosphere;
with
The trap unit is provided with a cooling unit inside the housing for cooling airflow passing through the housing ,
The trap unit further includes a trap plate inside the housing against which the airflow cooled by the cooling unit collides,
The heat treatment apparatus , wherein the trap section further includes, inside the housing, a housing section for housing a collection substrate on which the substance deposited by the cooling section is cooled by the cooling section . In the heat treatment apparatus according to claim 1 ,
A heat treatment apparatus, wherein the heat source includes a lamp for heating the substrate by irradiating it with light. In the heat treatment apparatus according to claim 1 or claim 2 ,
A heat treatment apparatus, wherein the substance is arsenic.

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