JP2019216287A - Heat treatment device and heat treatment method - Google Patents

Abstract

To provide a heat treatment device and a heat treatment method, which can reduce contamination in a chamber.SOLUTION: After preheating by irradiating a light from a halogen lamp HL to a lower surface of a semiconductor wafer W held by a susceptor 74 in a chamber 6, a flash heating is performed by irradiating a flash light to an upper surface from a flash lamp FL. A processing gas transmitted from a gas supply source 85 is heated by a heater 22 and is supplied to the chamber 6. A flow amount of the processing gas supplied to the chamber 6 is increased by a flow amount adjustment valve 21. By supplying the processing gas of a high temperature and a large flow amount in the chamber 6 and forming a gas flow, a contamination material discharged from a film of the semiconductor wafer W at the time of heat processing can be discharged to the out of chamber 6 and reduced the contamination in the chamber 6.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat treatment apparatus and a heat treatment method for heating a thin precision electronic substrate (hereinafter, simply referred to as a “substrate”) such as a semiconductor wafer by irradiating the substrate with light.

  In the semiconductor device manufacturing process, impurity introduction is an indispensable step for forming a pn junction in a semiconductor wafer. Currently, impurities are generally introduced by ion implantation and subsequent annealing. The ion implantation method is a technique in which impurity elements such as boron (B), arsenic (As), and phosphorus (P) are ionized and collided with a semiconductor wafer at a high acceleration voltage to physically perform impurity implantation. The implanted impurities are activated by annealing. At this time, if the annealing time is about several seconds or more, the implanted impurities are deeply diffused by heat, and as a result, the junction depth becomes deeper than required, and there is a possibility that good device formation may be hindered.

  Therefore, in recent years, flash lamp annealing (FLA) has attracted attention as an annealing technique for heating a semiconductor wafer in an extremely short time. Flash lamp annealing is a semiconductor wafer in which impurities are implanted by irradiating the surface of the semiconductor wafer with flash light using a xenon flash lamp (hereinafter, simply referred to as “flash lamp” means xenon flash lamp). Is a heat treatment technique for raising the temperature of only the surface of the material in a very short time (several milliseconds or less).

  The radiation spectral distribution of a xenon flash lamp ranges from the ultraviolet region to the near infrared region, has a shorter wavelength than the conventional halogen lamp, and almost coincides with the fundamental absorption band of a silicon semiconductor wafer. Therefore, when the semiconductor wafer is irradiated with flash light from the xenon flash lamp, the semiconductor wafer can be rapidly heated with little transmitted light. Further, it has been found that if the flash light irradiation is performed for a very short time of several milliseconds or less, only the vicinity of the surface of the semiconductor wafer can be selectively heated. For this reason, if the temperature is raised for a very short time by the xenon flash lamp, only the impurity activation can be performed without deeply diffusing the impurities.

  As a heat treatment apparatus using such a xenon flash lamp, in Patent Documents 1 and 2, a pulse emitting lamp such as a flash lamp is arranged on the front side of a semiconductor wafer, and a continuous lighting lamp such as a halogen lamp is arranged on the back side. And what performs desired heat processing by those combination is disclosed. In the heat treatment apparatuses disclosed in Patent Documents 1 and 2, the semiconductor wafer is preheated to a certain temperature with a halogen lamp or the like, and then heated to a desired processing temperature by pulse heating from a flash lamp.

JP-A-60-258928 JP 2005-527972 A

  Various films such as a resist film may be formed on a semiconductor wafer to be subjected to flash lamp annealing. When heat treatment is performed by irradiating such a semiconductor wafer with a film with flash light, structures in the chamber such as the inner wall of the chamber that accommodates the semiconductor wafer and the susceptor may be contaminated. This is presumed to be due to carbon-based contaminants adhering to structures in the chamber due to the burning of various films formed on the semiconductor wafer by flash heating.

  When the internal structure of the chamber becomes contaminated, it itself becomes a source of contamination for subsequent semiconductor wafers. Also, at the time of light irradiation, the light reflected on the inner wall surface of the chamber is also irradiated on the semiconductor wafer, but if the inner wall surface of the chamber is contaminated, the reflectance decreases at the contaminated site. The in-plane temperature distribution of the semiconductor wafer becomes non-uniform. This affects the processing result of the flash heating process, and also causes a problem that the semiconductor wafer is warped due to an uneven temperature distribution. Furthermore, as disclosed in Patent Documents 1 and 2, when lamps are arranged on both surfaces of a semiconductor wafer, there is a problem that if the susceptor is contaminated, light transmittance is reduced.

  The present invention has been made in view of the above problems, and has as its object to provide a heat treatment apparatus and a heat treatment method that can reduce contamination in a chamber.

  In order to solve the above problems, the invention according to claim 1 is a heat treatment apparatus that heats a substrate by irradiating the substrate with light, wherein a chamber accommodating the substrate, a susceptor supporting the substrate in the chamber, A light irradiating unit that irradiates light to a substrate supported by the susceptor, a gas supply unit that supplies a processing gas into the chamber, an exhaust unit that exhausts a gas in the chamber, and the chamber from the gas supply unit. A gas heating unit that heats the processing gas supplied to the gas supply unit, and the gas supply unit supplies the processing gas from a gas supply hole formed above a substrate supported by the susceptor, The exhaust unit exhausts gas from a gas exhaust hole formed below the substrate supported by the susceptor, and the gas heating unit supplies the gas into the chamber. The processing gas is characterized in that heating the treatment gas such that the 100 ° C. or more and the lowest substrate setting process below temperatures.

  Further, according to a second aspect of the present invention, in the heat treatment apparatus according to the first aspect of the present invention, the gas supply unit may be provided in the chamber from the gas supply hole through a buffer space having a smaller fluid resistance than the gas supply hole. The process gas is supplied.

  According to a third aspect of the present invention, in the heat treatment apparatus according to the first or second aspect, the processing gas is nitrogen, oxygen, or argon.

  According to a fourth aspect of the present invention, in the heat treatment apparatus according to any one of the first to third aspects, a flow rate increasing unit that increases a flow rate of the processing gas supplied from the gas supply unit to the chamber is provided. It is further characterized by comprising:

  According to a fifth aspect of the present invention, in the heat treatment apparatus according to any one of the first to fourth aspects, the light irradiation unit includes a flash lamp for irradiating the substrate with flash light from one side of the chamber. It is characterized by the following.

  According to a sixth aspect of the present invention, in the heat treatment apparatus according to the fifth aspect, the light irradiation unit further includes a continuous lighting lamp for irradiating the substrate with light from the other side of the chamber.

  According to a seventh aspect of the present invention, in the heat treatment method of heating the substrate by irradiating the substrate with light, a supporting step of supporting the substrate with a susceptor in the chamber, and a gas for supplying a processing gas into the chamber A supplying step, an exhausting step of exhausting gas in the chamber, and a light irradiating step of irradiating light to a substrate supported by the susceptor, wherein the gas supplying step is a processing gas to be supplied to the chamber. Including a gas heating step of heating the processing gas, supplying the processing gas from a gas supply hole formed above a substrate supported by the susceptor in the gas supply step, and supported by the susceptor in the exhaust step. Gas is exhausted from gas exhaust holes formed below the substrate, and in the gas heating step, the processing gas supplied into the chamber is exhausted. There characterized by heating the treatment gas such that the 100 ° C. or more and the lowest substrate setting process than temperature.

  The invention of claim 8 is the heat treatment method according to claim 7, wherein in the gas supply step, the gas is supplied from the gas supply hole into the chamber through a buffer space having a smaller fluid resistance than the gas supply hole. The process gas is supplied.

  A ninth aspect of the present invention is the heat treatment method according to the seventh or eighth aspect, wherein the processing gas is nitrogen, oxygen, or argon.

  According to a tenth aspect of the present invention, in the heat treatment method according to any one of the seventh to ninth aspects, the gas supply step includes a flow rate increasing step of increasing a flow rate of the processing gas supplied to the chamber. It is characterized by including.

  Further, according to an eleventh aspect of the present invention, in the heat treatment method according to any one of the seventh to tenth aspects, in the light irradiation step, the substrate is irradiated with flash light from one side of the chamber by a flash lamp. It is characterized by.

  According to a twelfth aspect of the present invention, in the heat treatment method according to the eleventh aspect, in the light irradiating step, the substrate is further irradiated with light from the other side of the chamber by a continuous lighting lamp.

  According to the first to sixth aspects of the present invention, a high-temperature processing gas flow is formed in the chamber to heat the processing gas supplied to the chamber, and contaminants emitted from the substrate during the heat processing are removed from the chamber. To reduce contamination in the chamber.

  In particular, according to the invention of claim 4, since the flow rate of the processing gas supplied to the chamber is increased, contaminants can be more effectively discharged out of the chamber.

  According to the seventh to twelfth aspects of the present invention, a high-temperature processing gas flow is formed in the chamber to heat the processing gas supplied to the chamber, and contaminants released from the substrate during the heating processing are discharged to the outside of the chamber. Evacuation can reduce contamination in the chamber.

  In particular, according to the tenth aspect of the present invention, since the flow rate of the processing gas supplied to the chamber is increased, contaminants can be more effectively discharged out of the chamber.

It is a longitudinal cross-sectional view which shows the structure of the heat processing apparatus concerning this invention. It is a perspective view which shows the whole external appearance of a holding | maintenance part. It is the top view which looked at the holding part from the upper surface. It is the side view which looked at the holding part from the side. It is a top view of a transfer mechanism. It is a side view of a transfer mechanism. It is a top view which shows arrangement | positioning of a some halogen lamp.

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

  FIG. 1 is a longitudinal sectional view showing a configuration of a 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 a disk-shaped semiconductor wafer W as a substrate by irradiating the semiconductor wafer W 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. Impurities have been implanted into the semiconductor wafer W before being loaded into the heat treatment apparatus 1, and activation processing of the impurities implanted by the heat treatment by the heat treatment apparatus 1 is performed. Note that, in FIG. 1 and each of the following drawings, the dimensions and the numbers of the respective parts are exaggerated or simplified as necessary for easy understanding.

  The heat treatment apparatus 1 includes a chamber 6 that accommodates a semiconductor wafer W, a flash heating unit 5 that houses a plurality of flash lamps FL, and a halogen heating unit 4 that houses 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. The heat treatment apparatus 1 includes a holding unit 7 that holds the semiconductor wafer W in a horizontal posture inside the chamber 6, and a transfer mechanism 10 that transfers the semiconductor wafer W between the holding unit 7 and the outside of the apparatus, Is provided. Further, the heat treatment apparatus 1 includes a mechanism for supplying a heated processing gas into the chamber 6. Furthermore, the heat treatment apparatus 1 includes a control unit 3 that controls the operation mechanisms provided in the halogen heating unit 4, the flash heating unit 5, and the chamber 6 to perform the heat treatment of the semiconductor wafer W.

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

  A reflection ring 68 is attached to the upper part of the inner wall surface of the chamber side part 61, and a reflection ring 69 is attached to the lower part. The reflection rings 68 and 69 are both formed in an annular shape. The upper reflecting ring 68 is attached by fitting from above the chamber side portion 61. On the other hand, the lower reflection ring 69 is mounted by being fitted from the lower side of the chamber side portion 61 and fastened with a screw (not shown). That is, the reflection rings 68 and 69 are both detachably attached to the chamber side portion 61. An inner space of 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 reflection rings 68 and 69 is defined as a heat treatment space 65.

  By attaching the reflection 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 surrounded by a central portion of the inner wall surface of the chamber side portion 61 where the reflection rings 68 and 69 are not mounted, a lower end surface of the reflection ring 68, and an upper end surface of the reflection ring 69 is formed. . 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.

  The chamber side portion 61 and the reflection rings 68 and 69 are formed of a metal material (for example, stainless steel) having excellent strength and heat resistance. Further, the inner peripheral surfaces of the reflection rings 68 and 69 are mirrored by electrolytic nickel plating.

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

Further, a gas supply hole 81 for supplying a processing gas to the heat treatment space 65 is formed in an upper portion of an 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 connected to a gas supply pipe 83 through 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 a gas supply source 85. A valve 84, a flow control valve 21, and a heater 22 are interposed in the middle of the gas supply pipe 83. The type of the processing gas supplied by the gas supply source 85 is not particularly limited, and is appropriately selected depending on the processing purpose. For example, nitrogen (N ₂ ), argon (Ar), helium ( Inert gas such as He) or a reactive gas such as oxygen (O ₂ ), hydrogen (H ₂ ), chlorine (Cl ₂ ), hydrogen chloride (HCl), ozone (O ₃ ), ammonia (NH ₃ ) Can be used.

  When the valve 84 is opened, the processing gas is supplied from the gas supply source 85 to the buffer space 82. The processing gas flowing 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. The flow rate of the processing gas flowing through the gas supply pipe 83 and supplied to the heat treatment space 65 is regulated by the flow rate adjustment valve 21. That is, the gas supply source 85 and the valve 84 correspond to a gas supply unit that supplies the processing gas into the chamber 6, and the flow control valve 21 corresponds to a flow rate increasing unit that increases the flow rate of the processing gas supplied to the chamber 6. . Note that a mass flow controller may be used as the flow rate increasing unit instead of the flow rate adjusting valve 21.

  The heater 22 heats the processing gas flowing through the gas supply pipe 83. The processing gas heated by the heater 22 is supplied from the gas supply holes 81 to the heat treatment space 65. That is, the heater 22 corresponds to a gas heating unit that heats the processing gas supplied to the chamber 6.

  On the other hand, a gas exhaust hole 86 for exhausting the gas in the heat treatment space 65 is formed in the lower portion of the inner wall of the chamber 6. The gas exhaust hole 86 is formed at a position lower than the recess 62 and may be provided in the reflection ring 69. The gas exhaust hole 86 is connected to a gas exhaust pipe 88 through 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. 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 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. Further, the gas supply source 85 and the exhaust unit 190 may be a mechanism provided in the heat treatment apparatus 1 or a utility of a factory where the heat treatment apparatus 1 is installed.

  A gas exhaust pipe 191 that exhausts the gas in the heat treatment space 65 is also connected to the tip of the transfer 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 unit 7. FIG. 3 is a plan view of the holding unit 7 as viewed from above, and FIG. 4 is a side view of the holding unit 7 as viewed from the side. The holding unit 7 includes a base ring 71, a connecting unit 72, and a susceptor 74. The base ring 71, the connecting portion 72, and the susceptor 74 are all formed of quartz. That is, the whole holding part 7 is made of quartz.

  The base ring 71 is an annular quartz member. The base ring 71 is supported on 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 along the circumferential direction on the upper surface of the base ring 71 having an annular shape. The connecting portion 72 is also a quartz member, and is fixed to the base ring 71 by welding. Note that the shape of the base ring 71 may be an arc shape in which a part is omitted from the ring shape.

  The flat susceptor 74 is supported by four connecting portions 72 provided on the base ring 71. The susceptor 74 is a substantially circular flat member formed of quartz. The diameter of the susceptor 74 is larger than the diameter of the semiconductor wafer W. That is, the susceptor 74 has a larger planar size than the semiconductor wafer W. A plurality (five in this embodiment) of guide pins 76 are provided upright on the upper surface of the susceptor 74. The five guide pins 76 are provided along the circumference of a circle concentric with the outer circumference of the susceptor 74. The diameter of the circle on which the five guide pins 76 are arranged is slightly larger than the diameter of the semiconductor wafer W. Each guide pin 76 is also formed of quartz. The guide pins 76 may be formed integrally with the susceptor 74 from a quartz ingot, or may be separately processed and attached to the susceptor 74 by welding or the like.

  The four connecting portions 72 erected on the base ring 71 and the lower surface of the peripheral portion 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, and the holding portion 7 is an integrally formed quartz member. When the base ring 71 of the holding unit 7 is supported on the wall surface of the chamber 6, the holding unit 7 is attached to the chamber 6. When the holding unit 7 is mounted on the chamber 6, the substantially disk-shaped susceptor 74 assumes a horizontal posture (a posture in which a normal line coincides with a vertical direction). The semiconductor wafer W carried into the chamber 6 is placed and held in a horizontal posture on the susceptor 74 of the holding unit 7 mounted on the chamber 6. Since the semiconductor wafer W is placed inside the circle formed by the five guide pins 76, horizontal displacement is prevented. The number of the guide pins 76 is not limited to five, but may be any number as long as the position shift of the semiconductor wafer W can be prevented.

  As shown in FIGS. 2 and 3, the susceptor 74 has an opening 78 and a cutout 77 penetrating vertically. The notch 77 is provided for passing the probe tip of the contact thermometer 130 using a thermocouple. On the other hand, the opening 78 is provided so that the radiation thermometer 120 receives radiation light (infrared light) emitted from the lower surface of the semiconductor wafer W held by the susceptor 74. Further, the susceptor 74 is provided with four through holes 79 through which the lift pins 12 of the transfer mechanism 10 to be described later pass through for transferring the semiconductor wafer W.

  FIG. 5 is a plan view of the transfer mechanism 10. 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 follows the generally annular recess 62. Two lift pins 12 are erected on each transfer arm 11. Each transfer arm 11 can be rotated by a horizontal movement mechanism 13. The horizontal movement mechanism 13 includes a transfer operation position (a position indicated by a solid line in FIG. 5) for transferring the pair of transfer arms 11 to the holding unit 7 and the semiconductor wafer W held by the holding unit 7. It is moved horizontally between the retracted positions (two-dot chain line positions in FIG. 5) that do not overlap in plan view. As the horizontal movement mechanism 13, each transfer arm 11 may be rotated by an individual motor, or a pair of transfer arms 11 may be interlocked by a single motor using a link mechanism. It may be moved.

  The pair of transfer arms 11 are moved up and down together with the horizontal moving mechanism 13 by the lifting mechanism 14. When the lifting 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 upper end of 12 protrudes from the upper surface of 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 pins 12 are extracted from the through holes 79, and the horizontal movement mechanism 13 moves the pair of transfer arms 11 so as to open each of 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 unit 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. Note that an exhaust mechanism (not shown) is also provided in the vicinity of a portion where the drive unit (the horizontal movement mechanism 13 and the lifting mechanism 14) of the transfer mechanism 10 is provided, and the atmosphere around the drive unit of the transfer mechanism 10 is provided. 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 including a plurality of (30 in the present embodiment) xenon flash lamps FL inside the housing 51, and an upper part of the light source. And a reflector 52 provided so as to cover. A lamp light emission window 53 is mounted on the bottom of the casing 51 of the flash heating unit 5. The lamp light emission window 53 constituting the floor of the flash heating unit 5 is a plate-like 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 to heat the semiconductor wafer W by flash.

  Each of the plurality of flash lamps FL is a rod-shaped lamp having a long cylindrical shape, and the longitudinal direction of each of the flash lamps FL is along the main surface of the semiconductor wafer W held by the holding unit 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 has a rod-shaped glass tube (discharge tube) in which xenon gas is sealed and an anode and a cathode connected to a capacitor at both ends thereof, and an outer peripheral surface of the glass tube. And a triggered electrode. Since xenon gas is an electrical insulator, electricity does not flow into the glass tube in a normal state even if charges are accumulated in the capacitor. However, when the insulation is broken by applying a high voltage to the trigger electrode, the electricity stored in the capacitor flows instantaneously in the glass tube, and light is emitted by excitation of atoms or molecules of xenon at that time. 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 to 100 milliseconds, so that the continuous lighting such as the halogen lamp HL is possible. It has the characteristic that it can irradiate extremely strong light compared with a light source. That is, the flash lamp FL is a pulse light emitting 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 source that supplies power to the flash lamp FL.

  In addition, 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 formed of an aluminum alloy plate, and the surface (the surface facing the flash lamp FL) is roughened by blasting.

  A plurality of (in this embodiment, 40) halogen lamps HL are built in the halogen heating section 4 provided below the chamber 6. The halogen heating unit 4 is a light irradiation unit that heats the semiconductor wafer W by irradiating the heat treatment space 65 from below the chamber 6 through the lower chamber window 64 with a plurality of halogen lamps HL. The halogen heating unit 4 irradiates the lower surface of the semiconductor wafer W supported by the susceptor 74 through the quartz susceptor 74 with halogen light.

  FIG. 7 is a plan view showing the arrangement of the plurality of halogen lamps HL. In the present embodiment, 20 halogen lamps HL are provided in each of the upper and lower two stages. 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 unit 7 (that is, along the horizontal direction). Yes. 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 the region facing the peripheral 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 stage and the lower stage. Yes. That is, in both the upper and lower stages, the arrangement pitch of the halogen lamps HL is shorter in the peripheral part than in the central part of the lamp array. For this reason, it is possible to irradiate a larger amount of light to the peripheral portion of the semiconductor wafer W where the temperature is likely to decrease during heating by light irradiation from the halogen heating unit 4.

  Further, the lamp group composed of the upper halogen lamp HL and the lamp group composed of the lower halogen lamp HL are arranged so as to intersect in a lattice pattern. That is, a total of 40 halogen lamps HL are arranged such that the longitudinal direction of each of the upper halogen lamps HL is orthogonal to the longitudinal direction of each of the lower halogen lamps HL.

  The halogen lamp HL is a filament-type light source that emits light by making the filament incandescent by energizing the filament disposed inside the glass tube. Inside the glass tube, a gas obtained by introducing a trace amount of a halogen element (iodine, bromine, etc.) into an inert gas such as nitrogen or argon is enclosed. By introducing a halogen element, it is possible to set the filament temperature to a high temperature while suppressing breakage of the filament. Therefore, the halogen lamp HL has a characteristic that it has a longer life than a normal incandescent bulb and can continuously radiate strong light. That is, the halogen lamp HL is a continuous lighting lamp that emits light continuously for at least one second. 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.

  Further, the control unit 3 controls the various operation mechanisms described above 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 includes a CPU that is a circuit that performs various arithmetic processes, 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, control software, data, and the like. It has a magnetic disk to store. The processing in the heat treatment apparatus 1 proceeds as the CPU of the control unit 3 executes a predetermined processing program.

  Next, a processing procedure for 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) are added by an ion implantation method. The activation of the impurities is performed 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 air supply valve 84 is opened, and the exhaust valves 89 and 192 are opened to start supply and exhaust of air into the chamber 6. When the valve 84 is opened, the processing gas is supplied from the gas supply hole 81 to the heat treatment space 65. In the present embodiment, nitrogen is supplied from the gas supply source 85 into the chamber 6 as a processing gas. The flow rate of the nitrogen supplied into the chamber 6 is regulated by the flow control valve 21, and is set to 50 L / min to 60 L / min in the present embodiment.

  Further, the heater 22 heats the nitrogen passing through the gas supply pipe 83. In the present embodiment, the heater 22 heats nitrogen passing through the gas supply pipe 83 to 350 ° C. However, 350 ° C. is the temperature of nitrogen in the portion where the heater 22 is installed. The temperature is about 200 ° C. when the nitrogen heated to 350 ° C. by the heater 22 is supplied into the chamber 6 from the gas supply holes 81. This is because heat is taken from the nitrogen gas by the gas passage such as the gas supply pipe 83.

  When the valve 89 is opened together with the air supply, the gas in the chamber 6 is exhausted from the gas exhaust hole 86. By exhausting gas from the gas exhaust hole 86 while supplying air from the gas supply hole 81, the high-temperature nitrogen gas supplied from the upper part of the heat treatment space 65 in the chamber 6 flows downward, and from the lower part of the heat treatment space 65 Exhausted. Thus, a high-temperature nitrogen gas flow is formed in the heat treatment space 65 in the chamber 6.

  Further, when the valve 192 is opened, the gas in the chamber 6 is also exhausted from the transfer opening 66. Further, the atmosphere around the drive unit of the transfer mechanism 10 is also exhausted by an exhaust mechanism (not shown). The supply of the high-temperature nitrogen gas to the heat treatment space 65 in the chamber 6 is performed by processing the first semiconductor wafer W of a lot (a set of semiconductor wafers W to be processed under the same conditions under the same conditions). It has been running before it started. Further, at the time of heat treatment of the semiconductor wafer W in the heat treatment apparatus 1, high-temperature nitrogen gas is continuously supplied to the heat treatment space 65, and the supply amount is appropriately changed depending on the treatment process.

  Subsequently, the gate valve 185 is opened to open the transfer opening 66, and the semiconductor wafer W after ion implantation is transferred 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 carrying robot advances to a position directly above the holding unit 7 and stops. Then, the pair of transfer arms 11 of the transfer mechanism 10 move horizontally from the retreat position to the transfer operation position and move up, so that the lift pins 12 protrude from the upper surface of the susceptor 74 through the through holes 79 and the semiconductor wafer W Receive.

  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. When the pair of transfer arms 11 is lowered, the semiconductor wafer W is transferred from the transfer mechanism 10 to the susceptor 74 of the holding unit 7 and is held from below in a horizontal posture. The semiconductor wafer W is held by the holder 7 with the surface on which the pattern is formed and the impurities are implanted facing upward. The semiconductor wafer W is held on the upper surface of the susceptor 74 inside the five guide pins 76. The pair of transfer arms 11 lowered to below the susceptor 74 are retracted by the horizontal moving mechanism 13 to the retracted position, that is, to the inside of the concave portion 62.

  After the semiconductor wafer W is held from below by the holding unit 7 formed of quartz in a horizontal posture, the 40 halogen lamps HL of the halogen heating unit 4 are simultaneously turned on to start preheating (assist heating). Is done. 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 (the main surface opposite to the front surface) of the semiconductor wafer W. By receiving light from the halogen lamp HL, the semiconductor wafer W is preheated and the temperature rises. In addition, since the transfer arm 11 of the transfer mechanism 10 is retracted to the inside of the recess 62, there is no obstacle to heating by the halogen lamp HL.

  When performing the preliminary heating by the halogen lamp HL, the temperature of the semiconductor wafer W is measured by the contact-type thermometer 130. That is, the contact-type thermometer 130 having a built-in thermocouple contacts the lower surface of the semiconductor wafer W held by the holder 7 through the notch 77 of the susceptor 74 to measure the temperature of the wafer during the temperature rise. The measured temperature of the semiconductor wafer W is transmitted to the control unit 3. The controller 3 controls the output of the halogen lamp HL while monitoring whether or not the temperature of the semiconductor wafer W that is heated by light irradiation from the halogen lamp HL has reached a predetermined preheating temperature T1. That is, the control section 3 performs feedback control of the output of the halogen lamp HL based on the measurement value of the contact thermometer 130 so that the temperature of the semiconductor wafer W becomes the preheating temperature T1. The preheating temperature T1 is set to about 200 ° C. to 800 ° C., preferably about 350 ° C. to 600 ° C. (in this embodiment, 600 ° C.) at which impurities added to the semiconductor wafer W are not likely to diffuse due to heat. . When the temperature of the semiconductor wafer W is increased by light irradiation from the halogen lamp HL, the temperature measurement by the radiation thermometer 120 is not performed. This is because halogen light emitted from the halogen lamp HL enters the radiation thermometer 120 as disturbance light, and accurate temperature measurement cannot be performed.

  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 contact-type thermometer 130 reaches the preheating temperature T1, the control unit 3 adjusts the output of the halogen lamp HL to substantially reduce the temperature of the semiconductor wafer W. The preheating temperature T1 is maintained.

  By performing such preheating by the halogen lamp HL, the entire semiconductor wafer W is uniformly heated to the preheating temperature T1. At the stage of preheating by the halogen lamp HL, the temperature of the peripheral portion of the semiconductor wafer W where heat radiation is more likely to occur tends to be lower than that of the central portion, but the arrangement density of the halogen lamp HL in the halogen heating portion 4 is: The region facing the periphery is higher than the region facing the center of the semiconductor wafer W (see FIG. 7). For this reason, the light quantity irradiated to the peripheral part of the semiconductor wafer W which tends to generate heat increases, and the in-plane temperature distribution of the semiconductor wafer W in the preheating stage can be made uniform. Furthermore, since the inner peripheral surface of the reflection ring 69 attached to the chamber side portion 61 is a mirror surface, the amount of light reflected toward the peripheral edge of the semiconductor wafer W by the inner peripheral surface of the reflection ring 69 increases. The in-plane temperature distribution of the semiconductor wafer W in the preheating stage can be made more uniform.

  The flash lamp FL of the flash heating unit 5 irradiates the surface of the semiconductor wafer W with flash light when a predetermined time elapses after the temperature of the semiconductor wafer W reaches the preheating temperature T1 by light irradiation from the halogen lamp HL. . At this time, a 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 performed by irradiation.

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

  After the flash heating process is completed, the halogen lamp HL is also turned off after a predetermined time has elapsed. Thereby, the temperature of the semiconductor wafer W is rapidly lowered from the preheating temperature T1. The temperature of the semiconductor wafer W during the cooling is measured by the contact thermometer 130 or the radiation thermometer 120, and the measurement result is transmitted to the control unit 3. The control unit 3 monitors whether the temperature of the semiconductor wafer W has dropped to a predetermined temperature based on the measurement result. Then, after the temperature of the semiconductor wafer W falls to a predetermined temperature or less, the pair of transfer arms 11 of the transfer mechanism 10 move horizontally again from the retreat position to the transfer operation position and rise, so that the lift pins 12 The semiconductor wafer W protruding from the upper surface of the semiconductor wafer 74 and having undergone the heat treatment is received from the susceptor 74. Subsequently, the transfer opening 66 closed by the gate valve 185 is opened, and the semiconductor wafer W placed on the lift pins 12 is unloaded by the transfer robot outside the apparatus, and the heat treatment of the semiconductor wafer W in the heat treatment apparatus 1 is performed. Is completed.

  Incidentally, various films such as a resist film and an insulating film may be formed on the surface of the semiconductor wafer W to be processed. When heat treatment is performed by irradiating the semiconductor wafer W on which such a film is formed with flash light, carbon-based contaminants diffuse into the heat treatment space 65 in the chamber 6 due to combustion of the film, volatilization of residual solvent components, and the like. May be done. If the contaminants released to the heat treatment space 65 adhere to the inner wall surface of the chamber 6 or the internal structure of the chamber such as the susceptor 74, the adhering portion is contaminated. Such contamination not only serves as a source of contamination for the subsequent semiconductor wafer W, but also causes a disturbance in the illuminance distribution of the semiconductor wafer W during light irradiation heating.

  Therefore, in the present embodiment, the high-temperature processing gas heated by the heater 22 is supplied to the heat treatment space 65 in the chamber 6 to form a gas flow. By flowing a high-temperature processing gas into the chamber 6, contaminants released from the film of the semiconductor wafer W during the heat treatment can be discharged out of the chamber 6 to reduce contamination in the chamber 6. As a result, it is possible to suppress the contamination of the inner wall surface of the chamber 6, the internal structure of the chamber such as the susceptor 74, and the like.

  In order to obtain the effect of suppressing the contaminant from adhering to the structure in the chamber by supplying the high-temperature processing gas, the temperature of the processing gas at the time when the processing gas is supplied into the chamber 6 becomes 100 ° C. or more. Thus, the heater 22 needs to heat the processing gas passing through the gas supply pipe 83. As the temperature of the processing gas increases, the effect of suppressing contamination also increases. However, if the processing gas having an excessively high temperature is supplied, the heat treatment of the semiconductor wafer W will be affected. Therefore, the heater 22 must heat the processing gas passing through the gas supply pipe 83 so that the temperature of the processing gas at the time when the processing gas is supplied into the chamber 6 becomes lower than the set processing temperature of the semiconductor wafer W. When the processing temperature of the semiconductor wafer W is set in multiple stages, the heater 22 is set so that the temperature of the processing gas supplied into the chamber 6 becomes lower than the lowest set processing temperature. Heat the gas. In the present embodiment, the heater 22 heats the nitrogen gas passing through the gas supply pipe 83 so that the temperature of the nitrogen gas at the time when the nitrogen gas is supplied into the chamber 6 is lower than the preheating temperature T1.

  Further, by supplying a high-temperature processing gas into the chamber 6, it is possible to obtain a cleaning effect of removing contaminants which have already adhered to the inner wall surface of the chamber 6, the susceptor 74, and other internal structures.

  Further, as the flow rate of the processing gas supplied into the chamber 6 increases, the effect of discharging the contaminant out of the chamber 6 increases, and the contaminant can be suppressed from adhering to the structure in the chamber. In the present embodiment, the flow rate adjusting valve 21 increases the flow rate of the nitrogen gas to a large flow rate of 50 L / min to 60 L / min and supplies the nitrogen gas into the chamber 6 usually at a rate of 20 L / min to 30 L / min. . Thereby, the contaminant is discharged to the outside of the chamber 6 before adhering to the internal structure of the chamber, and the contamination in the chamber 6 can be reduced more effectively.

  The flow rate of the processing gas supplied into the chamber 6 may be 0.5 D / min to 5 D / min, where D is the volume in the chamber 6. By supplying the processing gas into the chamber 6 at such a large flow rate, the effect of discharging contaminants out of the chamber 6 can be enhanced, and the contamination in the chamber 6 can be more effectively reduced.

  Although the embodiments of the present invention have been described above, various changes other than those described above can be made in the present invention without departing from the gist thereof. For example, in the above embodiment, a high-temperature nitrogen gas is supplied into the chamber 6, but the type of the processing gas is not limited to the nitrogen gas, and may be oxygen or argon. Particularly, by heating and supplying a reactive gas such as oxygen into the chamber 6, the cleaning effect of removing contaminants already attached to the internal structure of the chamber can be further enhanced.

  In the above embodiment, the flash heating unit 5 is provided with 30 flash lamps FL. However, the present invention is not limited to this, and the number of flash lamps FL can be any number. . The flash lamp FL is not limited to a 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 may be any number as long as a plurality of halogen lamps HL are arranged in the upper and lower stages.

  The light irradiating unit that irradiates the semiconductor wafer W with light to heat it is not limited to the flash lamp FL or the halogen lamp HL, but may be a laser light source.

  The substrate to be processed by the heat treatment apparatus according to the present invention is not limited to a semiconductor wafer, and may be a glass substrate or a solar cell substrate used for a flat panel display such as a liquid crystal display device. 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 between a metal and silicon, or crystallization of polysilicon.

DESCRIPTION OF SYMBOLS 1 Heat treatment apparatus 3 Control part 4 Halogen heating part 5 Flash heating part 6 Chamber 7 Holding part 10 Transfer mechanism 21 Flow control valve 22 Heater 65 Heat treatment space 74 Susceptor 83 Gas supply pipe 85 Gas supply source HL Halogen lamp FL Flash lamp W Semiconductor Wafer

Claims (12)

A heat treatment apparatus that heats the substrate by irradiating the substrate with light,
A chamber for housing the substrate;
A susceptor for supporting the substrate in the chamber;
A light irradiating unit that irradiates light to the substrate supported by the susceptor,
A gas supply unit for supplying a processing gas into the chamber,
An exhaust unit that exhausts gas in the chamber,
A gas heating unit that heats the processing gas supplied to the chamber from the gas supply unit,
With
The gas supply unit supplies the processing gas from a gas supply hole formed above a substrate supported by the susceptor, and the exhaust unit is formed below a substrate supported by the susceptor. Exhaust gas from the gas exhaust hole,
The heat treatment apparatus according to claim 1, wherein the gas heating unit heats the processing gas such that the processing gas supplied into the chamber is equal to or higher than 100 ° C and lower than a lowest processing temperature set for the substrate. The heat treatment apparatus according to claim 1, wherein
The heat treatment apparatus according to claim 1, wherein the gas supply unit supplies the processing gas into the chamber from the gas supply hole via a buffer space having a smaller fluid resistance than the gas supply hole. The heat treatment apparatus according to claim 1 or 2,
The heat treatment apparatus according to claim 1, wherein the processing gas is nitrogen, oxygen, or argon. The heat treatment apparatus according to any one of claims 1 to 3,
The heat treatment apparatus further comprising a flow rate increasing unit that increases a flow rate of the processing gas supplied from the gas supply unit to the chamber. The heat treatment apparatus according to any one of claims 1 to 4,
The heat treatment apparatus according to claim 1, wherein the light irradiation unit includes a flash lamp for irradiating the substrate with flash light from one side of the chamber. The heat treatment apparatus according to claim 5,
The heat treatment apparatus according to claim 1, wherein the light irradiation unit further includes a continuous lighting lamp for irradiating the substrate with light from the other side of the chamber. A heat treatment method of heating the substrate by irradiating the substrate with light,
A supporting step of supporting the substrate with a susceptor in the chamber,
A gas supply step of supplying a processing gas into the chamber,
An exhaust step of exhausting gas in the chamber,
A light irradiation step of irradiating light to the substrate supported by the susceptor,
With
The gas supply step includes a gas heating step of heating the processing gas supplied to the chamber,
In the gas supply step, the processing gas is supplied from a gas supply hole formed above the substrate supported by the susceptor, and in the exhaust step, the processing gas is formed below the substrate supported by the susceptor. Exhaust gas from the gas exhaust hole,
In the gas heating step, the processing gas is heated such that the processing gas supplied into the chamber is equal to or higher than 100 ° C. and lower than a lowest processing temperature set for the substrate. The heat treatment method according to claim 7,
In the gas supply step, the processing gas may be supplied from the gas supply hole into the chamber through a buffer space having a smaller fluid resistance than the gas supply hole. In the heat treatment method according to claim 7 or 8,
The method according to claim 1, wherein the processing gas is nitrogen, oxygen, or argon. In the heat treatment method according to any one of claims 7 to 9,
The heat treatment method according to claim 1, wherein the gas supply step includes a flow rate increasing step of increasing a flow rate of the processing gas supplied to the chamber. In the heat treatment method according to any one of claims 7 to 10,
In the light irradiation step, the substrate is irradiated with flash light from one side of the chamber by a flash lamp. The heat treatment method according to claim 11,
The heat treatment method, further comprising irradiating the substrate with light from the other side of the chamber by a continuous lighting lamp in the light irradiation step.

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