JP6791693B2 - Heat treatment equipment - Google Patents

Description

The present invention relates to a heat treatment apparatus that heats a thin plate-shaped precision electronic substrate (hereinafter, simply referred to as “substrate”) such as a semiconductor wafer by irradiating the substrate with light.

In the manufacturing process of semiconductor devices, flash lamp annealing (FLA), which heats a semiconductor wafer in an extremely short time, has attracted attention. Flash lamp annealing uses a xenon flash lamp (hereinafter, simply referred to as "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 exposed. This is a heat treatment technique 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 coincides with the basic absorption band of the silicon semiconductor wafer. Therefore, when the semiconductor wafer is irradiated with the flash light from the xenon flash lamp, the transmitted light is small and the temperature of the semiconductor wafer can be rapidly raised. It has also been found that if the flash light is irradiated for an extremely short time of several milliseconds or less, the temperature can be selectively raised only near the surface of the semiconductor wafer.

Such flash lamp annealing is utilized for processes that require heating for a very short time, for example, activation of impurities injected into a semiconductor wafer. By irradiating the surface of a semiconductor wafer into which impurities have been implanted by the ion implantation method with flash light from a flash lamp, the surface of the semiconductor wafer can be raised to the activation temperature for a very short time, and the impurities are deeply diffused. Only impurity activation can be performed without causing it.

As a heat treatment apparatus using such a xenon flash lamp, for example, in Patent Document 1, a flash lamp is arranged on the front surface side of a semiconductor wafer, a halogen lamp is arranged on the back surface side, and a desired heat treatment is performed by a combination thereof. Things are disclosed. In the heat treatment apparatus disclosed in Patent Document 1, the semiconductor wafer is preheated to a certain temperature by a halogen lamp, and then the surface of the semiconductor wafer is heated to a desired processing temperature by flash irradiation from the flash lamp.

Japanese Unexamined Patent Publication No. 2015-18909

In the heat treatment apparatus disclosed in Patent Document 1, a plurality of rod-shaped halogen lamps, which are preheating sources, are arranged in a grid pattern in two upper and lower stages to form a rectangular light source region. When the semiconductor wafer is heated by such a preheating source, there is a problem that it is difficult to improve the uniformity of the in-plane temperature distribution of the semiconductor wafer. In particular, it has been difficult to adjust the temperature of the peripheral edge of the semiconductor wafer facing the four corners of the rectangular light source region. The reason is, for example, when a portion (so-called hot spot) where the temperature becomes higher than the surroundings occurs on the peripheral edge of the semiconductor wafer facing the four corners of the rectangular light source region, the output of the rod-shaped halogen lamp facing the portion is generated. This is because if the temperature is lowered, the temperature of other parts of the semiconductor wafer will be lower than that of the surroundings (so-called cold spot).

The present invention has been made in view of the above problems, and an object of the present invention is to provide a heat treatment apparatus capable of appropriately adjusting the temperature of the peripheral portion of a substrate.

In order to solve the above problems, the invention of claim 1 is a heat treatment apparatus for heating a substrate by irradiating the substrate with light, a chamber for accommodating the substrate and a holding portion for holding the substrate in the chamber. A light irradiation unit in which a plurality of rod-shaped lamps are arranged in a two-stage grid in a rectangular light source region including a region facing the main surface of the substrate held by the holding unit, and a light irradiation unit provided in addition to the plurality of rod-shaped lamps is characterized by comprising a an auxiliary lamp disposed in the four corners of the rectangular light source regions.

Further, the invention of claim 2 is characterized in that, in the heat treatment apparatus according to the invention of claim 1, the auxiliary lamp has a U-shape.

Further, the invention of claim 3 is characterized in that, in the heat treatment apparatus according to the invention of claim 2, a part of the auxiliary lamp has a shape along the edge portion of the substrate held by the holding portion. To do.

Further, the invention of claim 4 is characterized in that, in the heat treatment apparatus according to the invention of claim 1, the auxiliary lamp has a rod shape.

Further, the invention of claim 5 is the heat treatment apparatus according to the invention of claim 4, wherein the auxiliary lamp has the same length as the plurality of rod-shaped lamps, and the position is biased to one side from the center in the longitudinal direction. It is characterized by being provided with a filament.

The invention of claim 6 is the heat treatment apparatus according to any one of claims 1 to 5, wherein the plurality of rod-shaped lamps are lamps having filaments at both ends with a central portion in the longitudinal direction interposed therebetween. It is characterized by including.

According to the inventions of claims 1 to 6, since the auxiliary lamps are arranged at the four corners of the rectangular light source region in which a plurality of rod-shaped lamps are arranged in a grid pattern in two stages, the peripheral edge of the substrate facing the four corners. The temperature of the peripheral portion of the substrate can be adjusted appropriately by adjusting the temperature of the portion individually.

It is a vertical cross-sectional view which shows the structure of the heat treatment apparatus which concerns on this invention. It is a perspective view which shows the whole appearance of the holding part. It is a top view of the susceptor. It is sectional drawing of the susceptor. It is a top view of the transfer mechanism. It is a side view of the transfer mechanism. It is a top view which shows the arrangement of a plurality of halogen lamps. It is a figure which shows the arrangement structure of the auxiliary lamp. It is a top view of the semiconductor wafer at the time of preheating. It is a figure which shows the shape of the auxiliary lamp of the 2nd Embodiment. It is a figure which shows the shape of the auxiliary lamp of the 3rd Embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<First Embodiment>
FIG. 1 is a vertical cross-sectional view showing the configuration of the heat treatment apparatus 1 according to the present invention. The heat treatment apparatus 1 of the present embodiment is a flash lamp annealing apparatus that heats the semiconductor wafer W by irradiating the disk-shaped semiconductor wafer W as a substrate with flash light. The size of the semiconductor wafer W to be processed is not particularly limited, but is, for example, φ300 mm or φ450 mm. In addition, in FIG. 1 and each subsequent drawing, 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 for accommodating a semiconductor wafer W, a flash heating unit 5 containing a plurality of flash lamps FL, and a halogen heating unit 4 containing a plurality of halogen lamps HL. A flash heating unit 5 is provided on the upper side of the chamber 6, and a halogen heating unit 4 is provided on the lower side. Further, the heat treatment apparatus 1 includes a holding portion 7 that holds the semiconductor wafer W in a horizontal position inside the chamber 6, a transfer mechanism 10 that transfers the semiconductor wafer W between the holding portion 7 and the outside of the apparatus. To be equipped. Further, the heat treatment apparatus 1 includes a halogen heating unit 4, a flash heating unit 5, and a control unit 3 that controls each operation mechanism provided in the chamber 6 to execute heat treatment of the semiconductor wafer W.

The chamber 6 is configured by mounting quartz chamber windows above and below the tubular chamber side portion 61. The chamber side portion 61 has a substantially tubular shape with upper and lower openings, and the upper chamber window 63 is attached to the upper opening and closed, and the lower chamber window 64 is attached to the lower opening and closed. ing. The upper chamber window 63 constituting the ceiling portion of the chamber 6 is a disk-shaped member formed of quartz, and functions as a quartz window that transmits the flash light emitted from the flash heating portion 5 into the chamber 6. Further, the lower chamber window 64 constituting the floor portion of the chamber 6 is also a disk-shaped member formed of quartz, and functions as a quartz window that transmits light from the halogen heating portion 4 into the chamber 6.

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

By attaching the reflective rings 68 and 69 to the chamber side portion 61, a recess 62 is formed on the inner wall surface of the chamber 6. That is, a recess 62 is formed which is surrounded by the central portion of the inner wall surface of the chamber side portion 61 to which the reflection rings 68 and 69 are not mounted, the lower end surface of the reflection ring 68, and the upper end surface of the reflection ring 69. .. The recess 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. The chamber side 61 and the reflective rings 68 and 69 are made of a metal material (for example, stainless steel) having excellent strength and heat resistance.

Further, the chamber side portion 61 is provided with a transport opening (furnace port) 66 for carrying in and out the semiconductor wafer W into and out of the chamber 6. The transport opening 66 is openable and closable by a gate valve 185. The transport opening 66 is communicatively connected to the outer peripheral surface of the recess 62. Therefore, when the gate valve 185 opens the transport opening 66, the semiconductor wafer W is carried in from the transport opening 66 through the recess 62 into the heat treatment space 65 and the semiconductor wafer W is carried out from the heat treatment space 65. It can be performed. Further, when the gate valve 185 closes the transport opening 66, the heat treatment space 65 in the chamber 6 becomes a closed space.

Further, a gas supply hole 81 for supplying the processing gas to the heat treatment space 65 is formed in the upper part of the inner wall of the chamber 6. The gas supply hole 81 is formed at a position above the recess 62, and may be provided in the reflection ring 68. The gas supply hole 81 is communicated with the gas supply pipe 83 via a buffer space 82 formed in an annular shape inside the side wall of the chamber 6. The gas supply pipe 83 is connected to the processing gas supply source 85. Further, a valve 84 is inserted in the middle of the path of the gas supply pipe 83. When the valve 84 is opened, the processing gas is supplied from the processing gas supply source 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 having 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 treatment gas, an inert gas such as nitrogen (N ₂ ) or a reactive gas such as hydrogen (H ₂ ) or ammonia (NH ₃ ) can be used (nitrogen in this embodiment).

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 at a position below the recess 62, and may be provided in the reflection ring 69. The gas exhaust hole 86 is communicated with the gas exhaust pipe 88 via a buffer space 87 formed in an annular shape inside the side wall of the chamber 6. The gas exhaust pipe 88 is connected to the exhaust unit 190. Further, a valve 89 is inserted in the middle of the path of the gas exhaust pipe 88. When the valve 89 is opened, the gas in the heat treatment space 65 is discharged from the gas exhaust hole 86 to the gas exhaust pipe 88 via 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. Further, the processing gas supply source 85 and the exhaust unit 190 may be a mechanism provided in the heat treatment apparatus 1, or may be a utility of a factory in which the heat treatment apparatus 1 is installed.

Further, a gas exhaust pipe 191 for discharging the gas in the heat treatment space 65 is also connected to the tip of the transport opening 66. The gas exhaust pipe 191 is connected to the exhaust unit 190 via a valve 192. By opening the valve 192, the gas in the chamber 6 is exhausted through the transfer opening 66.

FIG. 2 is a perspective view showing the overall appearance of the holding portion 7. 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 in which a part is missing from the ring shape. This missing portion is provided to prevent interference between the transfer arm 11 of the transfer mechanism 10 described later and the base ring 71. By placing the base ring 71 on the bottom surface of the recess 62, the base ring 71 is supported on the wall surface of the chamber 6 (see FIG. 1). A plurality of connecting portions 72 (four in the present embodiment) are erected on the upper surface of the base ring 71 along the circumferential direction of the ring 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. FIG. 3 is a plan view of the susceptor 74. Further, FIG. 4 is a cross-sectional view of the susceptor 74. The susceptor 74 includes a holding plate 75, a guide ring 76, and a plurality of substrate support pins 77. The holding plate 75 is a substantially circular flat plate-shaped 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 plane size larger than that of the semiconductor wafer W.

A guide ring 76 is installed on the upper peripheral edge of the holding plate 75. The guide ring 76 is a ring-shaped member having an inner diameter larger than the diameter of the semiconductor wafer W. 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 a tapered surface that 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 is a flat holding surface 75a for holding the semiconductor wafer W. A plurality of substrate support pins 77 are erected on the holding surface 75a of the holding plate 75. In the present embodiment, a total of 12 board support pins 77 are erected at every 30 ° along the circumference of the outer circle (inner circle of the guide ring 76) of the holding surface 75a and the concentric circle. The diameter of the circle in which the 12 substrate support pins 77 are arranged (distance between the opposing substrate support pins 77) is smaller than the diameter of the semiconductor wafer W, and if the diameter of the semiconductor wafer W is φ300 mm, the diameter is φ270 mm to φ280 mm (this implementation). In the form, it is φ280 mm). 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 edge 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 base ring 71 of the holding portion 7 is supported on the wall surface of the chamber 6, so that the holding portion 7 is mounted on the chamber 6. When the holding portion 7 is mounted on the chamber 6, the holding plate 75 of the susceptor 74 is in 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 is a horizontal plane.

The semiconductor wafer W carried into the chamber 6 is placed and held in a horizontal posture on the susceptor 74 of the holding portion 7 mounted on the chamber 6. At this time, the semiconductor wafer W is supported by the 12 substrate support pins 77 erected on the holding plate 75 and held by the susceptor 74. More precisely, the upper ends of the 12 substrate support pins 77 come into contact with the lower surface of the semiconductor wafer W to support the semiconductor wafer W. Since the heights of the 12 substrate support pins 77 (distance from the upper end of the substrate support pins 77 to the holding surface 75a of the holding plate 75) are uniform, the semiconductor wafer W is placed in a horizontal position by the 12 substrate support pins 77. Can be supported.

Further, the semiconductor wafer W is supported by a plurality of substrate support pins 77 from the holding surface 75a of the holding plate 75 at a predetermined interval. The thickness of the guide ring 76 is larger than the height of the substrate support pin 77. Therefore, the horizontal misalignment of the semiconductor wafer W supported by the plurality of substrate support pins 77 is prevented by the guide ring 76.

Further, as shown in FIGS. 2 and 3, the holding plate 75 of the susceptor 74 is formed with an opening 78 that penetrates vertically. The opening 78 is provided for the radiation thermometer 120 (see FIG. 1) to receive synchrotron radiation (infrared light) emitted from the lower surface of the semiconductor wafer W held by the susceptor 74. That is, the radiation thermometer 120 receives the light radiated from the lower surface of the semiconductor wafer W held by the susceptor 74 through the opening 78, and the temperature of the semiconductor wafer W is measured by a separate detector. Further, the holding plate 75 of the susceptor 74 is provided with four through holes 79 through which the lift pin 12 of the transfer mechanism 10 described later penetrates for the transfer of the semiconductor wafer W.

FIG. 5 is a plan view of the transfer mechanism 10. Further, FIG. 6 is a side view of the transfer mechanism 10. The transfer mechanism 10 includes two transfer arms 11. The transfer arm 11 has an arc shape that generally follows an annular recess 62. Two lift pins 12 are erected on each transfer arm 11. Each transfer arm 11 is rotatable by a horizontal movement mechanism 13. The horizontal movement mechanism 13 has a transfer operation position (solid line position in FIG. 5) for transferring the semiconductor wafer W to the holding portion 7 and the semiconductor wafer W held by the holding portion 7. It is horizontally moved to and from the retracted position (the two-point chain line position in FIG. 5) that does not overlap in a plan view. The horizontal movement mechanism 13 may be one in which each transfer arm 11 is rotated by an individual motor, or a pair of transfer arms 11 are interlocked and rotated by one motor using a link mechanism. It may be something to move.

Further, the pair of transfer arms 11 are moved up and down together with the horizontal movement mechanism 13 by the elevating mechanism 14. When the elevating mechanism 14 raises the pair of transfer arms 11 at the transfer operation position, a total of four lift pins 12 pass through the through holes 79 (see FIGS. 2 and 3) formed in the susceptor 74, and the lift pins The upper end of 12 protrudes from the upper surface of the susceptor 74. On the other hand, when the elevating mechanism 14 lowers the pair of transfer arms 11 at the transfer operation position, the lift pin 12 is pulled out from the through hole 79, and the horizontal movement mechanism 13 moves the pair of transfer arms 11 so as to open each. 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 portion 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 unit (horizontal movement mechanism 13 and elevating mechanism 14) of the transfer mechanism 10 is provided, and the atmosphere around the drive unit of the transfer mechanism 10 is provided. Is configured to be discharged to the outside of the chamber 6.

Returning to FIG. 1, the flash heating unit 5 provided above the chamber 6 is a light source composed of a plurality of (30 in this embodiment) xenon flash lamp FL inside the housing 51, and above the light source. It is configured to include a reflector 52 provided so as to cover the above. Further, a lamp light radiation window 53 is attached to the bottom of the housing 51 of the flash heating unit 5. The lamp light emitting window 53 constituting the floor portion 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 emitting 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 emitting window 53 and the upper chamber window 63.

Each of the plurality of flash lamps FL is a rod-shaped lamp having a long cylindrical shape, and the longitudinal direction thereof 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 xenon flash lamp FL is attached to a rod-shaped glass tube (discharge tube) in which xenon gas is sealed inside and an anode and a cathode connected to a condenser are arranged at both ends thereof, and on the outer peripheral surface of the glass tube. It is provided with a cathode electrode. Since xenon gas is electrically an insulator, electricity does not flow in the glass tube under normal conditions even if electric charges are accumulated in the condenser. However, when a high voltage is applied to the trigger electrode to break the insulation, the electricity stored in the capacitor instantly flows into the glass tube, and light is emitted by the excitation of xenone atoms or molecules at that time. In such a xenon flash lamp FL, the electrostatic energy stored in the capacitor in advance is converted into an extremely short optical pulse of 0.1 millisecond to 100 millisecond, so that the halogen lamp HL is continuously lit. It has the feature that it can irradiate extremely strong light compared to a light source. That is, the flash lamp FL is a pulsed lamp that emits light instantaneously 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 supply that supplies power to the flash lamp FL.

Further, the reflector 52 is provided above the plurality of flash lamps FL so as to cover all of them. The basic function of the reflector 52 is to reflect the flash light emitted from the plurality of flash lamps FL toward the heat treatment space 65. 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 contains a plurality of halogen lamps HL (40 in this embodiment) inside the housing 41 as a main light source. The halogen heating unit 4 is a light irradiation unit that heats the semiconductor wafer W by irradiating the heat treatment space 65 with light from below the chamber 6 through the lower chamber window 64 by a plurality of halogen lamps HL.

FIG. 7 is a plan view showing the arrangement of a plurality of halogen lamps HL, which are the main light sources of the halogen heating unit 4. 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 portion 7, and 20 halogen lamps HL are also arranged in the lower stage farther from the holding portion 7 than in the upper stage. Each halogen lamp HL is a rod-shaped lamp having a long cylindrical shape. The 20 halogen lamps HL in both the upper and lower stages 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 and lower stages is a horizontal plane.

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

Further, the lamp group composed of the halogen lamp HL in the upper stage and the lamp group composed of the halogen lamp HL in the lower stage are arranged so as to intersect in a grid pattern. That is, a total of 40 halogen lamps HL are arranged so 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 orthogonal to each other. There is. A rectangular light source region is formed by arranging a plurality of rod-shaped halogen lamps HL in a grid pattern in two upper and lower stages.

The halogen lamp HL is a filament type light source that incandescents the filament and emits light by energizing the filament arranged inside the glass tube. Inside the glass tube, a gas in which a small amount of a halogen element (iodine, bromine, etc.) is introduced into an inert gas such as nitrogen or argon is sealed. By introducing the halogen element, it becomes possible to set the temperature of the filament to a high temperature while suppressing the breakage of the filament. Therefore, the halogen lamp HL has a characteristic that it has a longer life and can continuously irradiate strong light as compared with a normal incandescent lamp. That is, the halogen lamp HL is a continuously lit lamp that continuously emits light for at least 1 second or longer. Further, since the halogen lamp HL is a rod-shaped lamp, it has a long life, and by arranging the halogen lamp HL along the horizontal direction, the radiation efficiency to the upper semiconductor wafer W becomes excellent.

The 40 halogen lamps HL include four special lamps in which the filament is divided into two. When such a lamp in which the filament is divided into two is particularly distinguished, it is referred to as a segment lamp SHL. However, the appearance shape of the segment lamp SHL is a rod shape of the same size and shape as other ordinary 36 halogen lamps HL, and a filament type light source in which filaments are arranged in an inert gas into which a small amount of halogen element is introduced. In that respect, the segment lamp SHL is the same as other halogen lamps HL. Therefore, when it is not necessary to distinguish the segment lamp SHL, the other normal 36 halogen lamps HL and the four segment lamps SHL are collectively collectively referred to as a halogen lamp HL.

A reflector 43 is also provided under 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 toward the heat treatment space 65.

Further, in the halogen heating unit 4 of the present embodiment, in addition to the 40 halogen lamps HL as the main light source, the auxiliary lamp AHL as the auxiliary light source is arranged. FIG. 8 is a diagram showing an arrangement configuration of the auxiliary lamp AHL. In the figure, for convenience of illustration, 36 ordinary halogen lamps HL are shown by dotted lines. A normal halogen lamp HL is a lamp in which one undivided filament is arranged from one end side to the other end side of a rod-shaped glass tube. Further, in FIG. 8, the segment lamp SHL is shown separately from the normal halogen lamp HL, and the semiconductor wafer W held by the holding portion 7 is projected and shown.

As shown in FIG. 8, the main surface of the semiconductor wafer W held by the holding portion 7 in a rectangular light source region formed by arranging 40 rod-shaped halogen lamps HL in a grid pattern in two upper and lower stages. The area facing the is completely included.

The segment lamp SHL includes filaments at both ends of a rod-shaped glass tube with a central portion in the longitudinal direction interposed therebetween. The filament is composed of, for example, a plurality of fine tungsten wires wound at a predetermined density. In the segment lamp SHL, the filaments on both sides are connected by a linear tungsten wire made of the same material as the filament. When the segment lamp SHL is energized, only the filaments on both sides divided into two are incandescent and emit light. That is, the segment lamp SHL does not emit light at the central portion of the rod-shaped glass tube in the longitudinal direction, but emits light at both sides of the central portion.

In the upper and lower two-stage grid lamp arrangement, two segment lamps SHL are included in each of the upper and lower stages. As shown in FIG. 8, a total of four segment lamps SHL so that the filaments divided into two face each other on the peripheral edge of the semiconductor wafer W corresponding to the four corners of the rectangular light source region formed by the 40 halogen lamps HL. Are arranged. Therefore, each segment lamp SHL irradiates two points on the peripheral edge of the semiconductor wafer W facing the four corners of the rectangular light source region. Hereinafter, the peripheral edges of the semiconductor wafer W facing the four corners of the rectangular light source region formed by the 40 halogen lamps HL are also referred to as "four corners of the semiconductor wafer W".

Eight auxiliary lamps AHL are arranged as auxiliary light sources in the halogen heating unit 4. In the first embodiment, the external shape of each auxiliary lamp AHL is U-shaped. The light emitting method of each auxiliary lamp AHL is the same filament method as the above halogen lamp HL. That is, the auxiliary lamp AHL encloses an inert gas in which a small amount of halogen element is introduced inside a U-shaped glass tube, and arranges a U-shaped filament.

Two of the eight auxiliary lamps AHL are arranged at each of the four corners of the rectangular light source region formed by the 40 halogen lamps HL. The outputs of the eight auxiliary lamps AHL are individually controlled by the control unit 3. As shown in FIG. 8, each auxiliary lamp AHL is arranged so that the tip portions thereof face the four corners of the semiconductor wafer W. As a result, each auxiliary lamp AHL can irradiate any of the four corners of the semiconductor wafer W with light by lighting.

The control unit 3 controls the above-mentioned various operation mechanisms provided in the heat treatment apparatus 1. The configuration of the control unit 3 as hardware is the same as that of a general computer. That is, the control unit 3 stores a CPU, which is a circuit that performs various arithmetic processes, a ROM, which is a read-only memory for storing basic programs, a RAM, which is a read / write memory for storing various information, and control software and data. It has a magnetic disk to store. The processing in the heat treatment apparatus 1 proceeds when the CPU of the control unit 3 executes a predetermined processing program.

In addition to the above configuration, the heat treatment apparatus 1 prevents an excessive temperature rise of the halogen heating unit 4, the flash heating unit 5, and the chamber 6 due to the thermal energy generated from the halogen lamp HL and the flash lamp FL during the heat treatment of the semiconductor wafer W. Therefore, it has various cooling structures. For example, a water cooling pipe (not shown) is provided on the wall of the chamber 6. Further, the halogen heating unit 4 and the flash heating unit 5 have an air-cooled structure in which a gas flow is formed inside to exhaust heat. In addition, air is also supplied to the gap between the upper chamber window 63 and the lamp light radiation window 53 to cool the flash heating unit 5 and the upper chamber window 63.

Next, the processing procedure of the semiconductor wafer W in the heat treatment apparatus 1 will be described. The semiconductor wafer W to be processed here is a semiconductor substrate to which impurities (ions) have been added by the ion implantation method. Activation of the impurities is carried out by flash light irradiation heat treatment (annealing) by the heat treatment apparatus 1. The processing procedure of the heat treatment apparatus 1 described below proceeds by the control unit 3 controlling each operation mechanism of the heat treatment apparatus 1.

First, the gate valve 185 is opened to open the transfer opening 66, and the semiconductor wafer W is carried into the heat treatment space 65 in the chamber 6 through the transfer opening 66 by a transfer robot outside the apparatus. The semiconductor wafer W carried in by the transfer robot advances to a position directly above the holding portion 7 and stops. Then, the pair of transfer arms 11 of the transfer mechanism 10 move horizontally from the retracted position to the transfer operation position and rise, so that the lift pin 12 protrudes from the upper surface of the holding plate 75 of the susceptor 74 through the through hole 79. Receives the semiconductor wafer W. At this time, the lift pin 12 rises above the upper end of the substrate support pin 77.

After the semiconductor wafer W is placed on the lift pin 12, the transfer robot exits the heat treatment space 65, and the transfer opening 66 is closed by the gate valve 185. Then, as the pair of transfer arms 11 descend, the semiconductor wafer W is handed over from the transfer mechanism 10 to the susceptor 74 of the holding portion 7 and held in a horizontal posture from below. The semiconductor wafer W is supported by a plurality of substrate support pins 77 erected on the holding plate 75 and held by the susceptor 74. Further, the semiconductor wafer W is held by the holding portion 7 with the surface on which the pattern is formed and the impurities are injected as the upper surface. A predetermined distance 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 75a of the holding plate 75. The pair of transfer arms 11 lowered to the lower side of the susceptor 74 are retracted to the retracted position, that is, inside the recess 62 by the horizontal movement mechanism 13.

Further, after the transfer opening 66 is closed by the gate valve 185 to make the heat treatment space 65 a closed space, the atmosphere in the chamber 6 is adjusted. Specifically, the valve 84 is opened and the processing gas is supplied to the heat treatment space 65 from the gas supply hole 81. In the present embodiment, nitrogen is supplied to the heat treatment space 65 in the chamber 6 as a processing gas. Further, the valve 89 is opened and the gas in the chamber 6 is exhausted from the gas exhaust hole 86. As a result, the processing gas supplied from the upper part of the heat treatment space 65 in the chamber 6 flows downward and is exhausted from the lower part of the heat treatment space 65, and the heat treatment space 65 is replaced with a nitrogen atmosphere. Further, when the valve 192 is opened, the gas in the chamber 6 is also exhausted from the transport opening 66. Further, the atmosphere around the drive unit of the transfer mechanism 10 is also exhausted by the exhaust mechanism (not shown).

After the inside of the chamber 6 is replaced with a nitrogen atmosphere and the semiconductor wafer W is held from below in a horizontal position by the susceptor 74 of the holding unit 7, the 40 halogen lamps HL of the halogen heating unit 4 are turned on all at once to prepare. Heating (assisted heating) is started. The halogen light emitted from the halogen lamp HL passes through the lower chamber window 64 and the susceptor 74 formed of quartz and is irradiated from the back surface of the semiconductor wafer W. By receiving the light irradiation from the halogen lamp HL, the semiconductor wafer W is preheated 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 heating by the halogen lamp HL.

When preheating with the halogen lamp HL, the temperature of the semiconductor wafer W is measured by the radiation thermometer 120. That is, the radiation thermometer 120 receives infrared light radiated from the back surface of the semiconductor wafer W held by the susceptor 74 through the opening 78, and measures the wafer temperature during temperature rise. The measured temperature of the semiconductor wafer W is transmitted to the control unit 3. The control unit 3 controls the output of the halogen lamp HL while monitoring whether or not the temperature of the semiconductor wafer W, which is raised by light irradiation from the halogen lamp HL, has reached a predetermined preheating temperature T1. That is, the control unit 3 feedback-controls the output of the halogen lamp HL so that the temperature of the semiconductor wafer W becomes the preheating temperature T1 based on the measured value by the radiation thermometer 120. The preheating temperature T1 is about 200 ° C. to 800 ° C., preferably about 350 ° C. to 600 ° C. (600 ° C. in the present embodiment).

After the temperature of the semiconductor wafer W reaches the preheating temperature T1, the control unit 3 maintains the semiconductor wafer W at the preheating temperature T1 for a while. Specifically, when the temperature of the semiconductor wafer W measured by the radiation thermometer 120 reaches the preheating temperature T1, the control unit 3 adjusts the output of the halogen lamp HL to substantially reserve the temperature of the semiconductor wafer W. The heating temperature is maintained at T1.

By the way, the 40 halogen lamps HL of the halogen heating unit 4 are all rod-shaped lamps. The 40 halogen lamps HL include four segment lamps SHL for adjusting the temperature at the four corners of the semiconductor wafer W. When the semiconductor wafer W is preheated by the halogen lamp HL, the temperature near the peripheral edge of the semiconductor wafer W tends to be different from that of the central portion, and the temperatures at the four corners of the semiconductor wafer W tend to be non-uniform. Therefore, the segment lamp SHL irradiates the four corners of the semiconductor wafer W with light to adjust the temperature of the four corners.

However, the following problems remain only by adjusting with the segment lamp SHL. FIG. 9 is a plan view of the semiconductor wafer W during preheating. As a result of improving the temperature distribution uniformity of the entire in-plane of the semiconductor wafer W by adjusting with the segment lamp SHL, only one of the four corners of the semiconductor wafer W becomes higher than the other regions and becomes a hot spot. May become. The reason why the temperature of only one of the four corners of the semiconductor wafer W is different in this way is that the structure of the chamber 6 is not necessarily symmetrical due to the presence of the transfer opening 66 and the like.

As shown in FIG. 9, it is assumed that a hot spot appears in the region C1 which is one of the four corners of the semiconductor wafer W. In order to eliminate this hot spot, it is necessary to reduce the output of the segment lamp SHL that has been irradiating the region C1 with light. However, since each segment lamp SHL irradiates two of the four corners of the semiconductor wafer W with light, if the output of the segment lamp SHL that irradiates the region C1 with light is reduced, the four corners of the semiconductor wafer W are irradiated. The illuminance of the region C2 or the region C3 is lowered, and the temperature is also lowered. Then, at the same time that the hot spot in the region C1 is eliminated, a cold spot is generated in the region C2 or the region C3. As a result, the in-plane temperature distribution uniformity of the semiconductor wafer W as a whole is not improved. That is, it is difficult to individually adjust the temperature of only a specific portion of the four corners of the semiconductor wafer W.

Therefore, the illuminances of the four corners of the semiconductor wafer W are individually adjusted by the auxiliary lamp AHL. Since each auxiliary lamp AHL irradiates light only at one of the four corners of the semiconductor wafer W, the illuminance at the four corners can be adjusted individually. For example, in the above example, if the output of the segment lamp SHL that has been irradiating the region C1 where the hot spot appears is reduced and the illuminance of the region C2 or the region C3 is reduced, the region C2 or the region C3 Light is irradiated from the auxiliary lamp AHL facing the region C2 or the region C3 to suppress the decrease in illuminance.

By doing so, the temperature of each of the four corners of the semiconductor wafer W during preheating can be individually adjusted, and the temperature of the peripheral portion of the semiconductor wafer W including the four corners can be appropriately adjusted. As a result, the in-plane temperature distribution uniformity of the semiconductor wafer W as a whole can be improved.

When the temperature of the semiconductor wafer W reaches the preheating temperature T1 and a predetermined time elapses, the flash lamp FL of the flash heating unit 5 irradiates the surface of the semiconductor wafer W with flash light. At this time, a part of the flash light radiated from the flash lamp FL goes directly into the chamber 6, and a part of the other part is once reflected by the reflector 52 and then goes into the chamber 6, and these flash lights The semiconductor wafer W is flash-heated by irradiation.

Since the flash heating is performed by irradiating the flash light (flash) from the flash lamp 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 0.1 millisecond or more and 100 millisecond or less, in which the electrostatic energy stored in the capacitor in advance is converted into an extremely short optical pulse. It is a strong flash. Then, the surface temperature of the semiconductor wafer W flash-heated by the flash light irradiation from the flash lamp FL momentarily rises to the processing temperature T2 of 1000 ° C. or higher, and the impurities injected into the semiconductor wafer W are activated. After that, the surface temperature drops rapidly. As described above, in the heat treatment apparatus 1, since the surface temperature of the semiconductor wafer W can be raised and lowered in an extremely short time, the impurities are activated while suppressing the diffusion of the impurities injected into the semiconductor wafer W due to the heat. Can be done. Since the time required for the activation of impurities is extremely short compared to the time required for the thermal diffusion, the activation can be performed even for a short time in which diffusion of about 0.1 msecond to 100 msecond does not occur. Complete.

In the present embodiment, the temperatures of the four corners of the semiconductor wafer W are individually adjusted by the auxiliary lamp AHL to make the in-plane temperature distribution of the semiconductor wafer W uniform in the preheating step. As a result, the in-plane temperature distribution on the surface of the semiconductor wafer W during flash light irradiation can be made uniform.

After the flash heat treatment is completed, the halogen lamp HL is turned off after a lapse of a predetermined time. As a result, the semiconductor wafer W rapidly drops from the preheating temperature T1. The temperature of the semiconductor wafer W during the temperature decrease is measured by the radiation thermometer 120, and the measurement result is transmitted to the control unit 3. The control unit 3 monitors whether or not the temperature of the semiconductor wafer W has dropped to a predetermined temperature based on the measurement result of the radiation thermometer 120. Then, after the temperature of the semiconductor wafer W is lowered to a predetermined value or less, the pair of transfer arms 11 of the transfer mechanism 10 horizontally move from the retracted position to the transfer operation position again and rise, so that the lift pin 12 is a susceptor. The semiconductor wafer W that protrudes from the upper surface of the 74 and has been heat-treated is received from the susceptor 74. Subsequently, the transfer opening 66 closed by the gate valve 185 is opened, the semiconductor wafer W mounted on the lift pin 12 is carried out by a transfer robot outside the apparatus, and the semiconductor wafer W is heat-treated in the heat treatment apparatus 1. Is completed.

In the first embodiment, auxiliary lamps AHL having a U shape are arranged at the four corners of a rectangular light source region formed by the halogen lamp HL, and the temperatures of the four corners of the semiconductor wafer W are individually adjusted by the auxiliary lamp AHL. I'm adjusting. As a result, the temperature of the peripheral edge of the semiconductor wafer W including the four corners of the semiconductor wafer W can be appropriately adjusted during preheating by the halogen lamp HL, and the in-plane temperature distribution of the semiconductor wafer W during preheating can be made uniform. can do. As a result, the in-plane temperature distribution on the surface of the semiconductor wafer W during flash heating can be made uniform.

If the auxiliary lamp AHL is arranged, it may be considered that the segment lamp SHL is unnecessary, but if the rated output of the U-shaped auxiliary lamp AHL is lower than the rated output of the rod-shaped segment lamp SHL. I have no choice but. Therefore, in the configuration in which only the auxiliary lamp AHL is arranged without providing the segment lamp SHL, the four corners of the semiconductor wafer W cannot be sufficiently heated, and cold spots may occur at the four corners. Therefore, it is preferable to arrange a segment lamp SHL in addition to the auxiliary lamp AHL so as to compensate for the insufficient output of the U-shaped auxiliary lamp AHL.

<Second Embodiment>
Next, the second embodiment of the present invention will be described. The overall configuration of the heat treatment apparatus 1 of the second embodiment is substantially the same as that of the first embodiment. Further, the processing procedure of the semiconductor wafer W in the heat treatment apparatus 1 of the second embodiment is the same as that of the first embodiment. The second embodiment differs from the first embodiment in the shape of the auxiliary lamp AHL.

FIG. 10 is a diagram showing the shape of the auxiliary lamp AHL of the second embodiment. In the figure, the same elements as those in the first embodiment are designated by the same symbols as in FIG. In the second embodiment, four auxiliary lamps AHL are arranged. Then, as shown in FIG. 10, the auxiliary lamp AHL of the second embodiment has a U-shaped tip portion formed along the edge portion of the semiconductor wafer W held by the holding portion 7. The configuration of the remainder of the second embodiment except for the shape of the auxiliary lamp AHL is the same as that of the first embodiment.

Also in the second embodiment, the auxiliary lamps AHL are arranged at the four corners of the rectangular light source region formed by the halogen lamp HL, and the temperatures of the four corners of the semiconductor wafer W are individually adjusted by the auxiliary lamps AHL. Therefore, as in the first embodiment, the temperature of the peripheral portion of the semiconductor wafer W including the four corners of the semiconductor wafer W can be appropriately adjusted during the preheating by the halogen lamp HL, and the semiconductor wafer W during the preheating can be appropriately adjusted. In-plane temperature distribution can be made uniform.

Further, in the second embodiment, since a part of the auxiliary lamp AHL is shaped along the edge portion of the semiconductor wafer W held by the holding portion 7, the temperature of the edge portion of the semiconductor wafer W is particularly adjusted. Suitable for

<Third Embodiment>
Next, a third embodiment of the present invention will be described. The overall configuration of the heat treatment apparatus 1 of the third embodiment is substantially the same as that of the first embodiment. Further, the processing procedure of the semiconductor wafer W in the heat treatment apparatus 1 of the third embodiment is the same as that of the first embodiment. The third embodiment differs from the first embodiment in the shape of the auxiliary lamp AHL.

FIG. 11 is a diagram showing the shape of the auxiliary lamp AHL of the third embodiment. In the figure, the same elements as those in the first embodiment are designated by the same symbols as in FIG. As shown in FIG. 11, the auxiliary lamp AHL of the third embodiment is a rod-shaped lamp having a rod shape. The external shape of the auxiliary lamp AHL of the third embodiment is the same as that of the segment lamp SHL and the halogen lamp HL. That is, the auxiliary lamp AHL of the third embodiment encloses an inert gas in which a small amount of halogen element is introduced inside a glass tube having the same length and thickness as the segment lamp SHL and the halogen lamp HL, and also has a linear filament. Are arranged. However, in the auxiliary lamp AHL of the third embodiment, the filament is arranged at a position biased to one side of the center in the longitudinal direction thereof.

In the third embodiment, four auxiliary lamps AHL are arranged. Each auxiliary lamp AHL is arranged so that its filament portion is located at the four corners of a rectangular light source region formed by the halogen lamp HL, that is, the filament portion faces the four corners of the semiconductor wafer W. As a result, each auxiliary lamp AHL can irradiate any of the four corners of the semiconductor wafer W with light by lighting.

Also in the third embodiment, the auxiliary lamps AHL are arranged at the four corners of the rectangular light source region formed by the halogen lamp HL, and the temperatures of the four corners of the semiconductor wafer W are individually adjusted by the auxiliary lamps AHL. Therefore, as in the first embodiment, the temperature of the peripheral portion of the semiconductor wafer W including the four corners of the semiconductor wafer W can be appropriately adjusted during the preheating by the halogen lamp HL, and the semiconductor wafer W during the preheating can be appropriately adjusted. In-plane temperature distribution can be made uniform.

<Modification example>
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 spirit of the present invention. For example, the shape of the auxiliary lamp AHL arranged at the four corners of the rectangular light source region formed by the halogen lamp HL is not limited to the first to third embodiments, and may be an appropriate shape. For example, the auxiliary lamp AHL may be a point light source lamp. Further, the auxiliary lamp AHL of the third embodiment may be a rod-shaped lamp having a total length corresponding to the length of the filament.

Further, in the above embodiment, the flash heating unit 5 is provided with 30 flash lamp FLs, but the present invention is not limited to this, and the number of flash lamp FLs can be any number. .. Further, the flash lamp FL is not limited to the xenon flash lamp, and may be a krypton flash lamp. Further, the number of halogen lamps HL provided in the halogen heating unit 4 is not limited to 40, and any number can be used as long as a plurality of halogen lamps HL are arranged in a grid pattern in the upper and lower stages.

Further, the substrate to be processed by the heat treatment apparatus according to the present invention is not limited to the semiconductor wafer, and may be a glass substrate used for a flat panel display such as a liquid crystal display device or a substrate for a solar cell. Further, the technique according to the present invention may be applied to heat treatment of a high dielectric constant gate insulating film (High-k film), bonding of metal and silicon, or crystallization of polysilicon.

Further, the heat treatment technique according to the present invention is not limited to the flash lamp annealing device, but is also applied to a heat source device other than the flash lamp such as a single-wafer lamp annealing device using a halogen lamp and a CVD device. be able to. In particular, the technique according to the present invention can be suitably applied to a backside annealing apparatus in which a halogen lamp is arranged below the chamber and light is irradiated from the back surface of the semiconductor wafer to perform heat treatment.

1 Heat treatment device 3 Control unit 4 Halogen heating unit 5 Flash heating unit 6 Chamber 7 Holding unit 65 Heat treatment space 74 Suceptor 120 Radiation thermometer AHL Auxiliary lamp SHL Segment lamp FL Flash lamp HL Halogen lamp W Semiconductor wafer

Claims (6)

A heat treatment apparatus that heats a substrate by irradiating the substrate with light.
The chamber that houses the board and
A holding portion that holds the substrate in the chamber and
A light irradiation unit in which a plurality of rod-shaped lamps are arranged in a grid pattern in two stages in a rectangular light source region including a region facing the main surface of the substrate held by the holding unit.
Auxiliary lamps provided in addition to the plurality of rod-shaped lamps and arranged at the four corners of the rectangular light source area, and
A heat treatment apparatus comprising. In the heat treatment apparatus according to claim 1,
The auxiliary lamp is a heat treatment apparatus having a U-shape. In the heat treatment apparatus according to claim 2,
A heat treatment apparatus characterized in that a part of the auxiliary lamp has a shape along an edge portion of a substrate held by the holding portion. In the heat treatment apparatus according to claim 1,
The auxiliary lamp is a heat treatment apparatus having a rod shape. In the heat treatment apparatus according to claim 4,
The auxiliary lamp is a heat treatment apparatus having the same length as the plurality of rod-shaped lamps and having a filament at a position biased to one side of the center in the longitudinal direction. In the heat treatment apparatus according to any one of claims 1 to 5.
The plurality of rod-shaped lamps are heat treatment devices including lamps having filaments at both ends with a central portion in the longitudinal direction interposed therebetween.

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