JP2020004764A - Heat treatment method and heat treatment apparatus - Google Patents

Abstract

To provide a heat treatment method and a heat treatment apparatus capable of creating a temperature profile appropriately regardless of the heat-up time of a substrate.SOLUTION: After being preheated by a halogen lamp, a semiconductor wafer is heated by flush light irradiation from a flush lamp. Length of light emission wavelength of flush light irradiated from the flush lamp is adjustable appropriately. Data collection period (sampling interval) of a radiation thermometer for measuring the surface temperature of the semiconductor wafer is made variable, and the longer the length of light emission wavelength of flush light, the longer the data collection period. Even if the surface temperature rise and fall time of the semiconductor wafer changes due to the length of light emission wavelength of the flush light, temperature change can be included in the temperature profile with a constant number of data point until the surface temperature rises and passes the maximum temperature and then falls.SELECTED DRAWING: Figure 12

Description

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

  In a semiconductor device manufacturing process, impurity introduction is an essential step for forming a pn junction in a semiconductor wafer. At present, impurities are generally introduced by an ion implantation method and a subsequent annealing method. The ion implantation method is a technique in which an impurity element such as boron (B), arsenic (As), and phosphorus (P) is ionized and collides with a semiconductor wafer at a high acceleration voltage to physically implant impurities. The implanted impurities are activated by the annealing process. At this time, if the annealing time is about several seconds or more, the implanted impurities diffuse deeply due to heat, and as a result, the junction depth may be too deep as required, which may hinder favorable device formation.

  Thus, 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 method of irradiating the surface of a semiconductor wafer with flash light using a xenon flash lamp (hereinafter, simply referred to as a xenon flash lamp when simply referred to as a "flash lamp") to thereby implant a semiconductor wafer into which impurities are implanted. This is a heat treatment technique in which only the surface is heated in a very short time (several milliseconds or less).

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

  It is important to properly control the temperature of the semiconductor wafer in the heat treatment, not limited to the flash heating, and it is necessary to accurately measure the temperature of the semiconductor wafer during the heat treatment. Typically, in heat treatment of a semiconductor wafer, temperature measurement is performed by a non-contact radiation thermometer. Patent Literature 1 discloses a technique in which the surface temperature of a semiconductor wafer at the time of flash light irradiation is measured by a radiation thermometer, and a temperature profile in which the measured temperatures are plotted in a time series is disclosed. Based on the obtained temperature profile, it is possible to obtain the maximum temperature reached on the surface of the semiconductor wafer at the time of flash light irradiation, the amount of heat applied to the semiconductor wafer, and the like.

JP 2017-00450 A

  In flash heating, the surface temperature history of a semiconductor wafer changes depending on the waveform of flash light emitted from a flash lamp. For example, when flash light having a relatively long wavelength is irradiated, the surface temperature of the semiconductor wafer rises for a relatively long time (although the heating time for flash heating is at most 1 second at most). . Conversely, when flash light having a short wavelength is irradiated, the surface temperature of the semiconductor wafer also rises sharply.

  When plotting the temperature of the semiconductor wafer measured by the radiation thermometer at a predetermined sampling interval to a certain number of data to create a temperature profile, when the surface temperature of the semiconductor wafer has been rising for a relatively long time, In some cases, a temperature profile can be created only halfway through the temperature rise. In this case, it is not possible to obtain the maximum temperature of the semiconductor wafer or the amount of heat input from the temperature profile. On the other hand, if the surface temperature of the semiconductor wafer has risen rapidly, the entire temperature rise can be contained in the temperature profile, but the maximum temperature of the semiconductor wafer may not be obtained accurately.

  The present invention has been made in view of the above problems, and has as its object to provide a heat treatment method and a heat treatment apparatus capable of appropriately creating a temperature profile regardless of a substrate heating time.

  In order to solve the above problems, the invention according to claim 1 is a heat treatment method for heating a substrate by irradiating the substrate with flash light, wherein a flash light irradiation step of irradiating the surface of the substrate with flash light from a flash lamp; A temperature measurement step of measuring the surface temperature of the substrate with a radiation thermometer at a preset data collection cycle, and the flash light irradiation is started among a plurality of temperature data acquired in the temperature measurement step. And a profile creation step of creating a temperature profile by extracting a fixed number of temperature data before and after the temperature data. The data collection cycle is variable.

  In a second aspect of the present invention, in the heat treatment method according to the first aspect of the present invention, in the profile creation step, the temperature measured by the radiation thermometer is a predetermined number of times before the temperature data when the temperature reaches a threshold value. The acquired temperature data is used as starting point temperature data, and the fixed number of temperature data after the starting point temperature data is extracted.

  According to a third aspect of the present invention, in the heat treatment method according to the first or second aspect, the data collection cycle is determined in accordance with a waveform of the flash light irradiated in the flash light irradiation step. Features.

  According to a fourth aspect of the present invention, in the heat treatment method according to the third aspect of the present invention, the data collection cycle is determined based on a conversion table that associates a flash light waveform with a data collection cycle. .

  According to a fifth aspect of the present invention, in the heat treatment method according to the third or fourth aspect, the data collection cycle is set longer as the waveform of the flash light irradiated in the flash light irradiation step becomes longer. Features.

  According to a sixth aspect of the present invention, in a heat treatment apparatus for heating a substrate by irradiating the substrate with flash light, a chamber accommodating the substrate and a surface of the substrate accommodated in the chamber are irradiated with flash light. A flash lamp, a radiation thermometer that receives infrared light radiated from the surface of the substrate, measures the temperature of the surface at a preset data collection cycle, and measures and acquires the radiation thermometer. A profile creation unit that creates a temperature profile by extracting a certain number of temperature data before and after the flash lamp starts irradiation of the flash light among the plurality of temperature data, and the data collection cycle is variable. It is characterized by being performed.

  Also, the invention of claim 7 is the heat treatment apparatus according to claim 6, wherein the profile creation unit is a predetermined number of times before the temperature data when the temperature measured by the radiation thermometer reaches a threshold value. The acquired temperature data is used as starting point temperature data, and the fixed number of temperature data after the starting point temperature data is extracted.

  According to an eighth aspect of the present invention, in the heat treatment apparatus according to the sixth or seventh aspect, the cycle determining unit for determining the data collection cycle according to a waveform of the flash light irradiated by the flash lamp is further provided. It is characterized by having.

  In a ninth aspect of the present invention, in the heat treatment apparatus according to the eighth aspect of the present invention, the thermal processing apparatus further includes a storage unit for storing a conversion table in which a flash light waveform is associated with a data collection period, The data collection cycle is determined based on the corresponding table.

  According to a tenth aspect of the present invention, in the heat treatment apparatus according to the eighth or ninth aspect, the cycle determination unit increases the data collection cycle as the waveform of the flash light irradiated by the flash lamp becomes longer. It is characterized by doing.

  According to the first to fifth aspects of the present invention, since the data collection cycle of the radiation thermometer is variable, the data collection cycle can be changed according to the substrate heating time, and the substrate heating time can be changed. Regardless, the temperature profile can be appropriately created.

  In particular, according to the invention of claim 2, temperature data obtained a predetermined number or more before the temperature data when the temperature measured by the radiation thermometer reaches the threshold value is set as the starting point temperature data, and Since a certain number of temperature data is extracted, the temperature of the substrate at the time when the flash light irradiation is started can be reliably included in the temperature profile.

  In particular, according to the fifth aspect of the present invention, the longer the waveform of the flash light, the longer the data collection cycle. Therefore, even if the temperature rise time of the substrate is prolonged by the flash light of a long waveform, the temperature change of the substrate is converted into a temperature profile. Can be included.

  According to the sixth to tenth aspects of the present invention, since the data collection cycle of the radiation thermometer is variable, it is possible to change the data collection cycle according to the temperature rise time of the substrate. Regardless, the temperature profile can be appropriately created.

  In particular, according to the invention of claim 7, temperature data obtained a predetermined number or more before the temperature data when the temperature measured by the radiation thermometer reaches the threshold value is set as the starting point temperature data, and Since a certain number of temperature data is extracted, the temperature of the substrate at the time when the flash light irradiation is started can be reliably included in the temperature profile.

  In particular, according to the tenth aspect of the present invention, the longer the waveform of the flash light, the longer the data collection cycle. Therefore, even if the temperature rise time of the substrate is prolonged by the flash light having a long waveform, the temperature change of the substrate is represented by the temperature profile. Can be included.

It is a longitudinal section showing the composition of the heat treatment equipment concerning the present invention. It is a perspective view which shows the whole external appearance of a holding part. It is a top view of a susceptor. It is sectional drawing of a susceptor. It is a top view of a transfer mechanism. It is a side view of a transfer mechanism. It is a top view showing arrangement of a plurality of halogen lamps. FIG. 2 is a diagram illustrating a drive circuit of a flash lamp. It is a block diagram which shows the structure of the high-speed radiation thermometer unit including the main part of an upper radiation thermometer. FIG. 6 is a diagram illustrating an example of a conversion table. FIG. 3 is a diagram showing a light emission waveform of a flash lamp. FIG. 4 is a diagram illustrating an example of a change in the surface temperature of a semiconductor wafer during flash light irradiation. FIG. 6 is a diagram illustrating another example of a change in the surface temperature of the semiconductor wafer during flash light irradiation.

  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 in FIG. 1 is a flash lamp annealing apparatus that heats a semiconductor wafer W having a disc shape 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 (φ300 mm in the present embodiment). 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 containing 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 above the chamber 6, and a halogen heating unit 4 is provided below the chamber 6. The heat treatment apparatus 1 further includes a holding unit 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 unit 7 and the outside of the apparatus, Is provided. Further, the heat treatment apparatus 1 includes a control unit 3 that controls each operation mechanism provided in the halogen heating unit 4, the flash heating unit 5, and the chamber 6 to execute the heat treatment of the semiconductor wafer W.

  The chamber 6 is configured by mounting a quartz chamber window above and below a cylindrical chamber side portion 61. The chamber side portion 61 has a substantially cylindrical shape with an open top and bottom, an upper chamber window 63 is mounted and closed on an upper opening, and a lower chamber window 64 is mounted and closed on a lower opening. ing. The upper chamber window 63 that forms the ceiling of the chamber 6 is a disk-shaped member formed of quartz, and functions as a quartz window that transmits flash light emitted from the flash heating unit 5 into the chamber 6. The lower chamber window 64 constituting the floor of the chamber 6 is also a disc-shaped member formed of quartz, and functions as a quartz window for transmitting light from the halogen heating unit 4 into the chamber 6.

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

  By attaching the reflection rings 68 and 69 to the chamber side 61, a concave portion 62 is formed on the inner wall surface of the chamber 6. That is, a concave portion 62 is formed which is 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. . 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 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, a transfer opening (furnace opening) 66 for carrying the semiconductor wafer W into and out of the chamber 6 is formed in the chamber side portion 61. The transport opening 66 can be opened and closed by a gate valve 185. The transport opening 66 is connected to the outer peripheral surface of the recess 62 in communication. For this reason, when the gate valve 185 opens the transfer opening 66, the semiconductor wafer W is loaded into the heat treatment space 65 from the transfer opening 66 through the concave portion 62 and unloaded from the heat treatment space 65. It can be performed. When the gate valve 185 closes the transfer opening 66, the heat treatment space 65 in the chamber 6 becomes a closed space.

  Further, a through hole 61a and a through hole 61b are formed in the chamber side portion 61. The through hole 61a is a cylindrical hole for guiding infrared light emitted from the upper surface of the semiconductor wafer W held by a susceptor 74 described later to the infrared sensor 29 of the upper radiation thermometer 25. On the other hand, the through-hole 61b is a cylindrical hole for guiding infrared light emitted from the lower surface of the semiconductor wafer W to the lower radiation thermometer 20. The through-hole 61a and the through-hole 61b are provided to be inclined with respect to the horizontal direction such that their axes in the through direction intersect with the main surface of the semiconductor wafer W held by the susceptor 74. At the end of the through hole 61a on the side facing the heat treatment space 65, a transparent window 26 made of a calcium fluoride material that transmits infrared light in a wavelength range that can be measured by the upper radiation thermometer 25 is mounted. A transparent window 21 made of a barium fluoride material that transmits infrared light in a wavelength range that can be measured by the lower radiation thermometer 20 is attached to an end of the through hole 61b on the side facing the heat treatment space 65. .

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 concave portion 62, and may be provided on 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 processing gas supply source 85. A valve 84 is inserted in the middle 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 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. As the processing gas, for example, an inert gas such as nitrogen (N ₂ ), a reactive gas such as hydrogen (H ₂ ), ammonia (NH ₃ ), or a mixed gas obtained by mixing them can be used. In the embodiment, nitrogen gas).

  On the other hand, a gas exhaust hole 86 for exhausting the gas in the heat treatment space 65 is formed below the inner wall of the chamber 6. The gas exhaust hole 86 is formed at a position lower than the concave portion 62, and may be provided on the reflection ring 69. The gas exhaust hole 86 is connected to a 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 part 190. A valve 89 is inserted in the middle 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. Note that 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 a utility of a factory where the heat treatment apparatus 1 is installed.

  Further, a gas exhaust pipe 191 for discharging gas in the heat treatment space 65 is also connected to the end of the transfer opening 66. The gas exhaust pipe 191 is connected to an 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. The holding section 7 includes a base ring 71, a connecting section 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 entire holding portion 7 is formed of quartz.

  The base ring 71 is an arc-shaped quartz member in which a part is omitted from the ring shape. The missing portion is provided to prevent interference between a transfer arm 11 of the transfer mechanism 10 described below and the base ring 71. The base ring 71 is supported on the wall surface of the chamber 6 by being placed on the bottom surface of the concave portion 62 (see FIG. 1). A plurality of connecting portions 72 (four in this embodiment) are erected on the upper surface of the base ring 71 along the circumferential direction of the 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. FIG. 4 is a 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 plate-shaped member formed 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 larger planar size than the semiconductor wafer W.

  A guide ring 76 is provided on a peripheral edge of the upper surface of the holding plate 75. The guide ring 76 is an annular member having an inner diameter larger than the diameter of the semiconductor wafer W. 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 has a tapered surface that widens upward from the holding plate 75. The guide ring 76 is formed of the same quartz as 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 inside the guide ring 76 on the upper surface of the holding plate 75 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 twelve substrate support pins 77 are erected every 30 ° along the circumference of the outer circumference of the holding surface 75a (the inner circumference of the guide ring 76). The diameter of the circle in which the twelve substrate support pins 77 are arranged (the distance between the opposing substrate support pins 77) is smaller than the diameter of the semiconductor wafer W. If the diameter of the semiconductor wafer W is φ300 mm, φ270 mm to φ280 mm (this embodiment) (Φ270 mm in the form). Each substrate support pin 77 is formed 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 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. By supporting the base ring 71 of the holder 7 on the wall surface of the chamber 6, the holder 7 is mounted on the chamber 6. When the holding unit 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 unit 7 mounted on the chamber 6. At this time, the semiconductor wafer W is supported by twelve substrate support pins 77 erected on the holding plate 75 and held by the susceptor 74. More precisely, the upper ends of the twelve substrate support pins 77 contact the lower surface of the semiconductor wafer W to support the semiconductor wafer W. Since the height of the twelve substrate support pins 77 (the distance from the upper end of the substrate support pins 77 to the holding surface 75a of the holding plate 75) is uniform, the semiconductor wafer W is placed in a horizontal posture by the twelve substrate support pins 77. Can be supported.

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

  As shown in FIGS. 2 and 3, the holding plate 75 of the susceptor 74 has an opening 78 penetrating vertically. The opening 78 is provided for the lower radiation thermometer 20 to receive radiation light (infrared light) radiated from the lower surface of the semiconductor wafer W. That is, the lower radiation thermometer 20 receives light radiated from the lower surface of the semiconductor wafer W through the opening 78 and the transparent window 21 attached to the through hole 61b of the chamber side portion 61, and receives the temperature of the semiconductor wafer W. Is measured. Further, the holding plate 75 of the susceptor 74 is provided with four through holes 79 through which the lift pins 12 of the transfer mechanism 10, which will 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 is formed in a circular arc shape along the generally annular concave portion 62. Each transfer arm 11 is provided with two lift pins 12 standing upright. The transfer arm 11 and the lift pins 12 are formed of quartz. Each transfer arm 11 is rotatable by a horizontal moving mechanism 13. The horizontal moving mechanism 13 moves the pair of transfer arms 11 to a transfer operation position (solid line position in FIG. 5) where the semiconductor wafer W is transferred to the holding unit 7 and the semiconductor wafer W held by the holding unit 7. The horizontal movement is performed between a retracted position (a position indicated by a two-dot chain line in FIG. 5) that does not overlap in a plan view. The horizontal moving mechanism 13 may be configured to rotate each transfer arm 11 by an individual motor, or may be rotated by a single motor using a link mechanism to link a pair of transfer arms 11. It may be moved.

  Further, the pair of transfer arms 11 is moved up and down by the elevating mechanism 14 together with the horizontal moving mechanism 13. 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, pulls out the lift pins 12 from the through holes 79, and moves the horizontal transfer mechanism 13 to open the pair of transfer arms 11, The transfer arm 11 moves to the retreat position. The retracted position of the pair of transfer arms 11 is immediately above the base ring 71 of the holding unit 7. Since the base ring 71 is placed on the bottom surface of the concave portion 62, the retreat position of the transfer arm 11 is inside the concave portion 62. It should be noted that an exhaust mechanism (not shown) is also provided near the portion where the driving section (the horizontal moving mechanism 13 and the elevating mechanism 14) of the transfer mechanism 10 is provided, and the atmosphere around the driving section 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 composed of a plurality of (30 in this embodiment) xenon flash lamps FL and a light source above the light source. And a reflector 52 provided so as to cover. Further, a lamp light emission window 53 is mounted on the bottom of the housing 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-shaped quartz window formed of quartz. When the flash heating unit 5 is installed above the chamber 6, the lamp light emission window 53 faces the upper chamber window 63. The flash lamp FL irradiates the heat treatment space 65 with flash light from above the chamber 6 through the lamp light emission window 53 and the upper chamber window 63.

  Each of the plurality of flash lamps FL is a rod-shaped lamp having a long cylindrical shape, and has a longitudinal direction 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.

  FIG. 8 is a diagram showing a drive circuit of the flash lamp FL. As shown in the figure, a capacitor 93, a coil 94, a flash lamp FL, and an IGBT (insulated gate bipolar transistor) 96 are connected in series. As shown in FIG. 8, the control unit 3 includes a pulse generator 31 and a waveform setting unit 32 and is connected to the input unit 33. As the input unit 33, various known input devices such as a keyboard, a mouse, and a touch panel can be employed. The waveform setting unit 32 sets the waveform of the pulse signal based on the input content from the input unit 33, and the pulse generator 31 generates the pulse signal according to the waveform.

  The flash lamp FL has a rod-shaped glass tube (discharge tube) 92 in which xenon gas is sealed and an anode and a cathode are disposed at both ends thereof, and a trigger electrode provided on the outer peripheral surface of the glass tube 92. 91. A predetermined voltage is applied to the capacitor 93 by the power supply unit 95, and an electric charge corresponding to the applied voltage (charging voltage) is charged. Further, a high voltage can be applied to the trigger electrode 91 from the trigger circuit 97. The timing at which the trigger circuit 97 applies a voltage to the trigger electrode 91 is controlled by the control unit 3.

  The IGBT 96 is a bipolar transistor in which a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is incorporated in the gate portion, and is a switching element suitable for handling large power. A pulse signal is applied to the gate of the IGBT 96 from the pulse generator 31 of the control unit 3. When a voltage higher than a predetermined value (High voltage) is applied to the gate of the IGBT 96, the IGBT 96 is turned on, and when a voltage lower than the predetermined value (Low voltage) is applied, the IGBT 96 is turned off. Thus, the drive circuit including the flash lamp FL is turned on and off by the IGBT 96. When the IGBT 96 is turned on / off, the connection between the flash lamp FL and the corresponding capacitor 93 is interrupted, and the current flowing through the flash lamp FL is on / off controlled.

  Even if the IGBT 96 is turned on while the capacitor 93 is charged and a high voltage is applied to both electrodes of the glass tube 92, the xenon gas is an electrically insulating material, so that the xenon gas is a glass in a normal state. No electricity flows through tube 92. However, when the trigger circuit 97 applies a high voltage to the trigger electrode 91 to break the insulation, a current flows instantaneously into the glass tube 92 due to the discharge between the two electrodes, thereby exciting the xenon atoms or molecules at that time. Emits light.

  The drive circuit as shown in FIG. 8 is individually provided for each of the plurality of flash lamps FL provided in the flash heating unit 5. In the present embodiment, since 30 flash lamps FL are arranged in a plane, 30 drive circuits as shown in FIG. 8 are provided corresponding to them. Therefore, the current flowing through each of the 30 flash lamps FL is individually turned on / off by the corresponding IGBT 96.

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

  The halogen heater 4 provided below the chamber 6 has a plurality of (40 in this embodiment) halogen lamps HL inside the housing 41. The halogen heater 4 is a light irradiator 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.

  FIG. 7 is a plan view showing an arrangement of a plurality of halogen lamps HL. The forty halogen lamps HL are arranged in two upper and lower stages. Twenty halogen lamps HL are arranged in an upper stage near the holding unit 7 and 20 halogen lamps HL are arranged in a lower stage farther from the holding unit 7 than the upper stage. Each of the halogen lamps HL is a rod-shaped lamp having a long cylindrical shape. The 20 halogen lamps HL in the upper and lower rows are arranged so that their respective longitudinal directions are parallel to each other along the main surface of the semiconductor wafer W held by the holding section 7 (that is, along the horizontal direction). I have. 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 lamps HL is higher in a region facing the peripheral portion than in a region facing the center of the semiconductor wafer W held by the holding portion 7 in both the upper stage and the lower stage. I have. That is, in both upper and lower stages, the arrangement pitch of the halogen lamps HL is shorter at the periphery than at the center 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, a lamp group composed of the upper halogen lamps HL and a lamp group composed of the lower halogen lamps HL are arranged so as to intersect in a grid pattern. That is, a total of 40 halogen lamps HL are arranged such that the longitudinal direction of the 20 halogen lamps HL arranged in the upper stage and the longitudinal direction of the 20 halogen lamps HL arranged in the lower stage are orthogonal to each other. I have.

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

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

  The control unit 3 controls the above-described 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 includes a CPU which is a circuit for performing various arithmetic processing, a ROM which is a read-only memory for storing a basic program, a RAM which is a readable and writable memory for storing various information, and control software and data. It has a magnetic disk for storing. The processing in the heat treatment apparatus 1 proceeds when the CPU of the control unit 3 executes a predetermined processing program. The control unit 3 includes a pulse generator 31 and a waveform setting unit 32 (FIG. 8). The waveform setting unit 32 sets the waveform of the pulse signal based on the input content from the input unit 33, and the pulse is set accordingly. Generator 31 outputs a pulse signal to the gate of IGBT 96.

  Further, as shown in FIG. 1, the heat treatment apparatus 1 includes an upper radiation thermometer 25 and a lower radiation thermometer 20. The upper radiation thermometer 25 is a high-speed radiation thermometer for measuring a rapid temperature change on the upper surface of the semiconductor wafer W when flash light is emitted from the flash lamp FL.

  FIG. 9 is a block diagram showing the configuration of the high-speed radiation thermometer unit 101 including the main part of the upper radiation thermometer 25. The infrared sensor 29 of the upper radiation thermometer 25 is mounted on the outer wall surface of the chamber side 61 so that its optical axis coincides with the axis of the through-hole 61a in the through direction. The infrared sensor 29 receives infrared light emitted from the upper surface of the semiconductor wafer W held by the susceptor 74 through the transparent window 26 of calcium fluoride. The infrared sensor 29 includes an optical element of InSb (indium antimony), and its measurement wavelength range is 5 μm to 6.5 μm. The transparent window 26 made of calcium fluoride selectively transmits infrared light in the wavelength range measured by the infrared sensor 29. The resistance of the InSb optical element changes according to the intensity of the received infrared light. The infrared sensor 29 including the InSb optical element can perform high-speed measurement with a very short response time and a remarkably short sampling interval (about 20 microseconds at the shortest). The infrared sensor 29 is electrically connected to the high-speed radiation thermometer unit 101, and transmits a signal generated in response to light reception to the high-speed radiation thermometer unit 101.

  The high-speed radiation thermometer unit 101 includes a signal conversion circuit 102, an amplification circuit 103, an A / D converter 104, a temperature conversion unit 105, a profile creation unit 106, and a storage unit 107. The signal conversion circuit 102 is a circuit that converts a resistance change generated in the InSb optical element of the infrared sensor 29 in the order of a current change and a voltage change, and finally converts it into a signal of a voltage that is easy to handle and outputs the signal. is there. The signal conversion circuit 102 is configured using, for example, an operational amplifier. The amplification circuit 103 amplifies the voltage signal output from the signal conversion circuit 102 and outputs the voltage signal to the A / D converter 104. The A / D converter 104 converts the voltage signal amplified by the amplifier circuit 103 into a digital signal.

  The temperature conversion unit 105 and the profile creation unit 106 are function processing units realized by a CPU (not shown) of the high-speed radiation thermometer unit 101 executing a predetermined processing program. The temperature conversion unit 105 performs a predetermined calculation process on a signal output from the A / D converter 104, that is, a signal indicating the intensity of infrared light received by the infrared sensor 29, and converts the signal into a temperature. The temperature obtained by the temperature converter 105 is the temperature of the upper surface of the semiconductor wafer W. The infrared radiation sensor 29, the signal conversion circuit 102, the amplification circuit 103, the A / D converter 104, and the temperature conversion unit 105 constitute the upper radiation thermometer 25. The lower radiation thermometer 20 has substantially the same configuration as the upper radiation thermometer 25, but does not have to support high-speed measurement.

  In addition, the profile creation unit 106 creates a temperature profile indicating a temporal change in the temperature of the upper surface of the semiconductor wafer W by sequentially accumulating the temperature data acquired at regular intervals by the temperature conversion unit 105 in the storage unit 107. . As the storage unit 107, a known storage medium such as a magnetic disk or a memory can be used. The creation of the temperature profile will be described later in more detail.

  As shown in FIG. 9, the high-speed radiation thermometer unit 101 is electrically connected to the control unit 3 which is a controller of the entire heat treatment apparatus 1. The control unit 3 includes a period determining unit 35 in addition to the pulse generator 31 and the waveform setting unit 32 (not shown in FIG. 9). The cycle determining unit 35 is a function processing unit realized by the CPU of the control unit 3 executing a predetermined processing program. The processing content of the cycle determining unit 35 will be further described later.

  The display unit 34 and the input unit 33 are connected to the control unit 3. The control unit 3 displays various information on the display unit 34. The operator of the heat treatment apparatus 1 can input various commands and parameters from the input unit 33 while confirming the information displayed on the display unit 34. As the display unit 34 and the input unit 33, for example, a liquid crystal touch panel provided on the outer wall of the heat treatment apparatus 1 may be adopted. The storage unit 36 shown in FIG. 9 is a storage medium such as a magnetic disk or a memory of the control unit 3.

  In addition to the above-described configuration, the heat treatment apparatus 1 prevents an excessive rise in temperature of the halogen heating unit 4, the flash heating unit 5, and the chamber 6 due to heat 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 tube (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 cooling structure for forming a gas flow therein and discharging heat. Air is also supplied to the gap between the upper chamber window 63 and the lamp light emission window 53 to cool the flash heating unit 5 and the upper chamber window 63.

  Next, a processing operation in the heat treatment apparatus 1 will be described. First, a typical heat treatment procedure for a semiconductor wafer W to be processed will be described. Here, the semiconductor wafer W to be processed is a semiconductor substrate to which impurities (ions) are added by an ion implantation method. The activation of the impurities is performed by heat treatment (annealing) of flash light irradiation 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 valve 84 for air supply is opened, and the valves 89 and 192 for exhaust are opened, so that air supply and exhaust to the inside of the chamber 6 are started. When the valve 84 is opened, nitrogen gas is supplied from the gas supply hole 81 to the heat treatment space 65. When the valve 89 is opened, the gas in the chamber 6 is exhausted from the gas exhaust hole 86. Thereby, the nitrogen 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.

  When the valve 192 is opened, the gas in the chamber 6 is exhausted from the transfer opening 66. Further, the atmosphere around the drive section of the transfer mechanism 10 is also exhausted by an exhaust mechanism not shown. In the heat treatment of the semiconductor wafer W in the heat treatment apparatus 1, the nitrogen gas is continuously supplied to the heat treatment space 65, and the supply amount is appropriately changed according to the treatment process.

  Subsequently, the gate valve 185 is opened to open the transfer opening 66, and the semiconductor wafer W to be processed is carried into the heat treatment space 65 in the chamber 6 through the transfer opening 66 by the transfer robot outside the apparatus. At this time, there is a possibility that the atmosphere outside the apparatus may be involved when the semiconductor wafer W is loaded, but since the nitrogen gas is continuously supplied to the chamber 6, the nitrogen gas flows out from the transfer opening 66, and Entrapment of an external atmosphere can be minimized.

  The semiconductor wafer W carried in by the transfer robot advances to a position immediately above the holding unit 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 pins 12 protrude from the upper surface of the holding plate 75 of the susceptor 74 through the through holes 79. To receive the semiconductor wafer W. At this time, the lift pins 12 rise above the upper ends of the substrate support pins 77.

  After the semiconductor wafer W is placed on the lift pins 12, the transfer robot exits 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 supported by a plurality of substrate support pins 77 erected on a holding plate 75 and held by a susceptor 74. Further, the semiconductor wafer W is held by the holding unit 7 with the surface on which the pattern is formed and the impurities are implanted facing upward. A predetermined gap is formed between the back surface (the 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 that have descended to below the susceptor 74 are retracted by the horizontal moving mechanism 13 to the retracted position, that is, to the inside of the recess 62.

  After the semiconductor wafer W is held in a horizontal posture from below by the susceptor 74 of the holding unit 7 made of quartz, the 40 halogen lamps HL of the halogen heating unit 4 are simultaneously turned on to perform preliminary heating (assist 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 irradiates the lower surface of the semiconductor wafer W. Upon receiving 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 concave portion 62, it does not hinder the 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 lower radiation thermometer 20. That is, the lower radiation thermometer 20 receives infrared light radiated from the lower surface of the semiconductor wafer W held by the susceptor 74 through the opening 78 through the transparent window 21 and measures the temperature of the wafer 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 heated by the irradiation of light from the halogen lamp HL has reached a predetermined preheating temperature T1. That is, the control unit 3 performs feedback control of the output of the halogen lamp HL based on the measurement value of the lower radiation thermometer 20 so that the temperature of the semiconductor wafer W becomes the preheating temperature T1. As described above, the lower radiation thermometer 20 is a radiation thermometer for controlling the temperature of the semiconductor wafer W during preheating. The preheating temperature T1 is set to about 200 ° C. to 800 ° C., and preferably about 350 ° C. to 600 ° C. (600 ° C. in the present embodiment) at which impurities added to the semiconductor wafer W are not likely to be diffused by heat. .

  After the temperature of the semiconductor wafer W reaches the preheating temperature T1, the control unit 3 temporarily maintains the semiconductor wafer W at the preheating temperature T1. Specifically, when the temperature of the semiconductor wafer W measured by the lower radiation thermometer 20 reaches the pre-heating 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 peripheral portion is higher than the region facing the center of the semiconductor wafer W. Therefore, the amount of light applied to the peripheral portion of the semiconductor wafer W where heat is likely to be generated increases, and the in-plane temperature distribution of the semiconductor wafer W in the preheating stage can be made uniform.

  Further, the surface temperature of the semiconductor wafer W is measured by the upper radiation thermometer 25 from the time when the preheating of the semiconductor wafer W is performed. From the surface of the semiconductor wafer W to be heated, infrared light having an intensity corresponding to the temperature is emitted. The infrared light emitted from the surface of the semiconductor wafer W passes through the transparent window 26 and is received by the infrared sensor 29 of the upper radiation thermometer 25.

  A resistance change occurs in the InSb optical element of the infrared sensor 29 according to the intensity of the received infrared light. The resistance change generated in the InSb optical element of the infrared sensor 29 is converted into a voltage signal by the signal conversion circuit 102. After the voltage signal output from the signal conversion circuit 102 is amplified by the amplification circuit 103, the voltage signal is converted by the A / D converter 104 into a digital signal suitable for a computer to handle. Then, the temperature converter 105 performs predetermined arithmetic processing on the signal output from the A / D converter 104 to convert the signal into temperature data. That is, the upper radiation thermometer 25 receives infrared light radiated from the surface of the semiconductor wafer W to be heated, and measures the surface temperature of the semiconductor wafer W from the intensity of the infrared light.

  When a predetermined time elapses after the temperature of the semiconductor wafer W reaches the preheating temperature T1, the flash lamp FL of the flash heating unit 5 irradiates the surface of the semiconductor wafer W held by the susceptor 74 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 another part is once reflected by the reflector 52 and then goes into the chamber 6. The flash heating of the semiconductor wafer W is performed by the irradiation.

  When the flash lamp FL irradiates flash light, electric charges are stored in the capacitor 93 by the power supply unit 95 in advance. Then, in a state where the electric charge is accumulated in the capacitor 93, a pulse signal is output from the pulse generator 31 of the control unit 3 to the IGBT 96 to drive the IGBT 96 on and off.

  The waveform of the pulse signal can be defined by inputting from the input unit 33 a recipe in which the pulse width time (on time) and the pulse interval time (off time) are sequentially set as parameters. When the operator inputs such a recipe from the input unit 33 to the control unit 3, the waveform setting unit 32 of the control unit 3 sets a pulse waveform that repeats on and off in accordance with the input. Then, the pulse generator 31 outputs a pulse signal according to the pulse waveform set by the waveform setting unit 32. As a result, a pulse signal having a set waveform is applied to the gate of the IGBT 96, and ON / OFF driving of the IGBT 96 is controlled. Specifically, when the pulse signal input to the gate of IGBT 96 is on, IGBT 96 is on, and when the pulse signal is off, IGBT 96 is off.

  The control unit 3 controls the trigger circuit 97 to apply a high voltage (trigger voltage) to the trigger electrode 91 in synchronization with the timing when the pulse signal output from the pulse generator 31 is turned on. A pulse signal is input to the gate of the IGBT 96 in a state where the electric charge is accumulated in the capacitor 93, and a high voltage is applied to the trigger electrode 91 in synchronization with the timing at which the pulse signal is turned on. When is turned on, a current always flows between both electrodes in the glass tube 92, and light is emitted by the excitation of xenon atoms or molecules at that time.

  Thus, the 30 flash lamps FL of the flash heating unit 5 emit light, and the surface of the semiconductor wafer W held by the holding unit 7 is irradiated with flash light. Here, when the flash lamp FL emits light without using the IGBT 96, the charge stored in the capacitor 93 is consumed by one light emission, and the output waveform from the flash lamp FL has a width of 0.1. It is a simple single pulse of about millisecond to 10 millisecond. On the other hand, in the present embodiment, the supply of the charge from the capacitor 93 to the flash lamp FL is intermittently performed by the IGBT 96 by connecting the IGBT 96 as the switching element in the circuit and outputting a pulse signal to the gate thereof. The current flowing through the flash lamp FL is on / off controlled. As a result, the light emission of the flash lamp FL is chopper-controlled, so that the electric charge stored in the capacitor 93 is divided and consumed, and the flash lamp FL repeats blinking in a very short time. Since the next pulse is applied to the gate of the IGBT 96 before the current value flowing through the circuit completely becomes "0" and the current value increases again, the light emission output is maintained even while the flash lamp FL repeats blinking. It is not completely "0".

  By controlling the current flowing through the flash lamp FL by the IGBT 96 to be on or off, the light emission pattern (time waveform of the light emission output) of the flash lamp FL can be freely defined, and the light emission time and light emission intensity can be freely adjusted. . The on / off driving pattern of the IGBT 96 is defined by the pulse width time and the pulse interval time input from the input unit 33. That is, by incorporating the IGBT 96 into the drive circuit of the flash lamp FL, the light emission pattern of the flash lamp FL can be freely defined only by appropriately setting the pulse width time and the pulse interval time input from the input unit 33. You can do it.

  Specifically, for example, when the ratio of the time of the pulse width to the time of the pulse interval input from the input unit 33 is increased, the current flowing through the flash lamp FL increases and the light emission intensity increases. Conversely, when the ratio of the pulse width time to the pulse interval time input from the input unit 33 is reduced, the current flowing through the flash lamp FL decreases and the light emission intensity decreases. If the ratio of the pulse interval time and the pulse width time input from the input unit 33 is appropriately adjusted, the light emission intensity of the flash lamp FL is kept constant. Further, by increasing the total time of the combination of the pulse width time and the pulse interval time input from the input unit 33, the current continues to flow in the flash lamp FL for a relatively long time, and the light emission of the flash lamp FL The time gets longer. The light emission time of the flash lamp FL is appropriately set between 0.1 ms and 100 ms.

  In this way, the flash light is irradiated from the flash lamp FL onto the surface of the semiconductor wafer W for an irradiation time of 0.1 to 100 milliseconds, and the semiconductor wafer W is heated by flash. Then, the surface temperature of the semiconductor wafer W, which is flash-heated by irradiating the flash light from the flash lamp FL, instantaneously rose to a processing temperature T2 of 1000 ° C. or more, and the impurities implanted into the semiconductor wafer W were 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 by irradiating the flash light with an extremely short irradiation time. As a result, the impurities can be activated while suppressing diffusion of the impurities injected into the semiconductor wafer W due to heat. Since the time required for activating the impurity is extremely short as compared with the time required for thermal diffusion, the activation is performed even in a short time of about 0.1 to 100 milliseconds in which diffusion does not occur. Complete.

  Even when the surface temperature of the semiconductor wafer W rapidly rises and falls due to the flash light irradiation, the surface temperature is measured by the upper radiation thermometer 25. Since the upper radiation thermometer 25 measures the surface temperature of the semiconductor wafer W at an extremely short sampling interval, even if the surface temperature of the semiconductor wafer W suddenly changes during flash light irradiation, it can follow the change. is there.

  After the completion of the flash heating process, the halogen lamp HL is turned off after a lapse of a predetermined time. As a result, the temperature of 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 lower radiation thermometer 20, 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 lower radiation thermometer 20. 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 carried out by a transfer robot outside the apparatus, and the semiconductor wafer W is heated in the heat treatment apparatus 1. Is completed.

  In the heat treatment apparatus 1 of the present embodiment, the emission waveform of the flash lamp FL can be freely adjusted by the waveform of the pulse signal applied to the IGBT 96. FIG. 11 is a diagram showing a light emission waveform of the flash lamp FL. FIG. 11 shows two typical waveforms. When the total time of the combination of the pulse width time and the pulse interval time of the pulse signal is shortened, a light emission waveform having a relatively short light emission time is obtained as shown by a solid line in FIG. Conversely, when the total time of the combination of the pulse width time and the pulse interval time of the pulse signal is increased, a light emission waveform having a relatively long light emission time is obtained as shown by a dotted line in FIG.

  When flash light having a short light emission waveform as shown by the solid line in FIG. 11 is irradiated, the surface temperature of the semiconductor wafer W rapidly rises and falls in a short time. On the other hand, when flash light having a long emission waveform as shown by a dotted line in FIG. 11 is irradiated, the surface temperature of the semiconductor wafer W also gradually rises and falls over a relatively long time. However, since the irradiation time of the flash light is about 100 milliseconds at the longest, the surface temperature rise and fall time of the semiconductor wafer W is 1 second or less even when the flash light having a long emission waveform is irradiated.

  Even when the surface temperature of the semiconductor wafer W rapidly rises and falls by flash light irradiation, the surface temperature is measured by the upper radiation thermometer 25. Since the data collection cycle (sampling interval) of the upper radiation thermometer 25 is extremely short, for example, 40 microseconds, even if the surface temperature of the semiconductor wafer W rises and falls rapidly during flash light irradiation, the change can be measured. .

  The profile creation unit 106 sequentially accumulates a plurality of temperature data acquired by the upper radiation thermometer 25 at a fixed data collection period in the storage unit 107, thereby indicating a time change of the surface temperature of the semiconductor wafer W. A temperature profile is created. By analyzing the temperature profile created by the profile creation unit 106, it is possible to calculate the maximum temperature reached on the surface of the semiconductor wafer W at the time of flash light irradiation and the amount of heat applied to the semiconductor wafer W. At this time, if the number of data points of the temperature data constituting the temperature profile is excessively large, it takes a long time for data analysis. For this reason, the number of points of the temperature data for creating the temperature profile is defined as a fixed number, and is set to, for example, 3000 points in the present embodiment.

  However, when the surface temperature of the semiconductor wafer W rises and falls over a relatively long time by irradiating flash light having a long emission waveform, 3000 data points may not be sufficient. For example, when a temperature profile is created from temperature data of 3000 points acquired in a data collection cycle of 40 microseconds, a temperature profile over 120 milliseconds is created. However, if the rise and fall time of the surface temperature of the semiconductor wafer W at the time of flash light irradiation is 120 milliseconds or more, a part of the rise and fall period protrudes from the temperature profile. In this case, since the maximum temperature data at the time of flash light irradiation may not be included in the temperature profile, the maximum temperature cannot be obtained from the temperature profile. Further, since the entire surface temperature rise / fall period is not included in the temperature profile, it is impossible to calculate the amount of heat input to the semiconductor wafer W.

  On the other hand, when the surface temperature of the semiconductor wafer W sharply rises and falls by irradiating flash light having a short emission waveform, the maximum temperature at the time of flash light irradiation may not be measured in a data collection cycle of 40 microseconds. That is, if the surface of the semiconductor wafer W reaches the maximum temperature within 40 microseconds from the moment when the upper radiation thermometer 25 measures the temperature, the maximum temperature cannot be measured.

  For this reason, in the present embodiment, the data collection cycle of the upper radiation thermometer 25 is made variable according to the rise and fall time of the surface temperature of the semiconductor wafer W. Specifically, before the flash light irradiation, the cycle determination unit 35 determines the data collection cycle according to the length of the emission waveform of the flash light based on the conversion table stored in the storage unit 36 of the control unit 3. .

  FIG. 10 is a diagram illustrating an example of the conversion table. The “flash waveform” shown in the drawing is the length of the emission waveform of the flash light, more specifically, for example, the half width (full width at half maximum) of the emission waveform. In the conversion table, the length of the light emission waveform of the flash light is associated with the data collection cycle. The cycle determination unit 35 determines the data collection cycle of the upper radiation thermometer 25 from the length of the emission waveform of the flash light based on the conversion table in FIG. The length of the emission waveform of the flash light may be obtained by the control unit 3 from the processing recipe before the start of the processing. Alternatively, the operator of the heat treatment apparatus 1 may input the length of the emission waveform of the flash light from the input unit 33 before the start of the processing.

  According to the example of FIG. 10, when the half width of the emission waveform of the flash light is extremely short, that is, 0 ms or more and less than 0.6 ms, the cycle determination unit 35 determines the data collection cycle to be 20 microseconds. When the half width of the emission waveform of the flash light is 0.6 ms or more and less than 60 ms, the cycle determination unit 35 determines the data collection cycle to be 40 microseconds. Further, when the half width of the emission waveform of the flash light is relatively long, that is, not less than 60 milliseconds and less than 180 milliseconds, the cycle determination unit 35 determines the data collection cycle to be 80 microseconds. That is, the longer the waveform of the flash light emitted from the flash lamp FL, the longer the data collection cycle. The upper radiation thermometer 25 acquires the temperature data by measuring the surface temperature of the semiconductor wafer W at a data collection cycle set in advance by the cycle determination unit 35.

  FIG. 12 is a diagram illustrating an example of a change in the surface temperature of the semiconductor wafer W during flash light irradiation. In the example of FIG. 12, the length of the emission waveform of the flash light is extremely short, and the data collection cycle is set to 20 microseconds. From the stage where the semiconductor wafer W is preheated to the preheating temperature T1 by irradiation of light from the halogen lamp HL, the upper radiation thermometer 25 measures the surface temperature of the semiconductor wafer W at a data collection cycle of 20 microseconds. . The temperature data of the surface of the semiconductor wafer W obtained by the measurement by the upper radiation thermometer 25 is temporarily stored in the memory of the high-speed radiation thermometer unit 101 (not shown).

At time t12, flash light irradiation from the flash lamp FL starts, and the surface temperature of the semiconductor wafer W sharply rises from the preheating temperature T1. Then, at time t13, the surface temperature of the semiconductor wafer W reaches the threshold temperature _Tth . The threshold temperature _Tth is a predetermined temperature higher than the preheating temperature T1. In the present embodiment, the upper radiation thermometer 25 uses a predetermined number (for example, 500 points) before the temperature data when the surface temperature of the semiconductor wafer W measured by the upper radiation thermometer 25 reaches the threshold temperature _Tth . The acquired temperature data is set as the starting point temperature data. In the example of FIG. 12, the temperature data acquired by the upper radiation thermometer 25 at the time t11 is set as the starting point temperature data.

  The surface temperature of the semiconductor wafer W reaches the processing temperature T2 at time t14 by the flash light irradiation. The processing temperature T2 is the highest temperature reached on the surface of the semiconductor wafer W during flash light irradiation. After time 14, the surface temperature of the semiconductor wafer W rapidly drops from the processing temperature T2. The upper radiation thermometer 25 measures the surface temperature of the semiconductor wafer W even while the temperature of the surface of the semiconductor wafer W is rising and falling, and the acquired temperature data is stored in the memory.

  The temperature profile creation unit 106 extracts 3000 pieces of temperature data after the start point temperature data from the memory of the high-speed radiation thermometer unit 101 to create a temperature profile. It is at time t15 that the 3000th temperature data after the start point temperature data is acquired. That is, in the example of FIG. 12, the temperature profile is created from the temperature data of 3000 points acquired from the time t11 to the time 15. Since the data collection cycle is 20 microseconds, the time from time t11 to time t15 is 60 milliseconds, and a temperature profile is created from the temperature data of 3000 points over 60 milliseconds before and after the start of flash light irradiation. It will be. The created temperature profile may be displayed on the display unit 34.

Temperature data acquired a predetermined number of times before the temperature data at the time when the surface temperature of the semiconductor wafer W reaches the threshold temperature _Tth is set as the starting point temperature data, and the temperature profile is calculated from the temperature data of 3000 points after the starting point temperature data. Due to the preparation, the temperature profile from when the flash light irradiation is started from the preheating to when the surface temperature of the semiconductor wafer W rises and falls through the processing temperature T2 can be included in the temperature profile.

  In addition, the data collection cycle is set to a short time of 20 microseconds according to the length of the emission waveform of the flash light which is extremely short. For this reason, the resolution of the upper radiation thermometer 25 is high, and it is possible to reliably measure the highest attained temperature (processing temperature T2) of the surface of the semiconductor wafer W at the time of flash light irradiation. When the data collection cycle is short, the data collection period from time t11 to time t15 is also short. However, when the length of the emission waveform of the flash light is extremely short, the rise and fall time of the surface temperature of the semiconductor wafer W is short. The entire surface temperature rise / fall period can be included in the temperature profile. As a result, by analyzing the created temperature profile, it is possible to accurately calculate the maximum temperature reached on the surface of the semiconductor wafer W and the amount of heat applied to the semiconductor wafer W.

  FIG. 13 is a diagram illustrating another example of a change in the surface temperature of the semiconductor wafer W during flash light irradiation. In the example of FIG. 13, the length of the emission waveform of the flash light is relatively long, and the data collection cycle is set to 80 microseconds. From the stage where the semiconductor wafer W is preheated to the preheating temperature T1 by light irradiation from the halogen lamp HL, the upper radiation thermometer 25 measures and acquires the surface temperature of the semiconductor wafer W at a data collection cycle of 80 microseconds. The obtained temperature data is temporarily stored in the memory of the high-speed radiation thermometer unit 101.

At time t22, flash light irradiation from the flash lamp FL starts, and the surface temperature of the semiconductor wafer W rises from the preheating temperature T1. The heating rate in FIG. 13 is slower than the heating rate in FIG. Then, at time t23, the surface temperature of the semiconductor wafer W reaches the threshold temperature _Tth . The threshold temperature _Tth is a predetermined temperature higher than the preheating temperature T1. Similarly to the above, the upper radiation thermometer 25 acquires the temperature data by a predetermined number (for example, 500 points) earlier than the temperature data when the surface temperature of the semiconductor wafer W measured by the upper radiation thermometer 25 reaches the threshold temperature _Tth. The obtained temperature data is set as the starting point temperature data. In the example of FIG. 13, the temperature data acquired by the upper radiation thermometer 25 at the time t21 is set as the starting point temperature data.

  The surface temperature of the semiconductor wafer W reaches the processing temperature T2 at time t24 by the flash light irradiation. The processing temperature T2 is the highest temperature reached on the surface of the semiconductor wafer W during flash light irradiation. After time 24, the surface temperature of the semiconductor wafer W drops from the processing temperature T2. The upper radiation thermometer 25 measures the surface temperature of the semiconductor wafer W even while the temperature of the surface of the semiconductor wafer W is rising and falling, and the acquired temperature data is stored in the memory.

  The temperature profile creation unit 106 extracts 3000 pieces of temperature data after the start point temperature data from the memory of the high-speed radiation thermometer unit 101 to create a temperature profile. It is at time t25 that the 3000th temperature data after the start point temperature data is obtained. That is, in the example of FIG. 13, the temperature profile is created from the temperature data of 3000 points acquired from time t21 to time 25. Since the data collection cycle is 80 microseconds, the time from time t21 to time t25 is 240 milliseconds, and a temperature profile is created from 3000 temperature data over 240 milliseconds before and after the start of flash light irradiation. It will be. The created temperature profile may be displayed on the display unit 34.

Temperature data obtained a predetermined number of times before the temperature data when the surface temperature of the semiconductor wafer W reaches the threshold temperature _Tth is set as the starting point temperature data, and the temperature profile is calculated from the temperature data of 3000 points after the starting point temperature data. Since the temperature profile is formed, the temperature profile from when the flash light irradiation is started from the preheating, when the surface temperature of the semiconductor wafer W increases, and when the temperature decreases after passing through the processing temperature T2 can be included in the temperature profile.

  The data collection cycle is also set to 80 microseconds in accordance with the length of the emission waveform of the flash light, which is relatively long. In the example of FIG. 13, the length of the emission waveform of the flash light is relatively long, and the rise and fall time of the surface temperature of the semiconductor wafer W is also long. However, the data collection cycle is also relatively long at 80 microseconds. The data collection period up to t25 is four times that of the example of FIG. Therefore, even if the rise and fall time of the surface temperature of the semiconductor wafer W is long, the entire rise and fall period of the surface temperature can be included in the temperature profile. On the other hand, if the data collection cycle is long, the resolution of the upper radiation thermometer 25 decreases, but in the example of FIG. 13, the surface temperature of the semiconductor wafer W rises and falls relatively slowly, so the resolution of the upper radiation thermometer 25 Even if the temperature is somewhat low, the maximum temperature (processing temperature T2) of the surface of the semiconductor wafer W at the time of flash light irradiation can be reliably measured. As a result, by analyzing the created temperature profile, it is possible to accurately calculate the maximum temperature reached on the surface of the semiconductor wafer W and the amount of heat applied to the semiconductor wafer W.

  In the present embodiment, the length of the emission waveform of the flash light emitted from the flash lamp FL can be adjusted by the waveform of the pulse signal applied to the IGBT 96. The data collection cycle of the upper radiation thermometer 25 is variable according to the length of the emission waveform of the flash light. If the length of the light emission waveform of the flash light is short, the data collection period is set short, and if the length of the light emission waveform of the flash light is long, the data collection period is set long.

  When the length of the emission waveform of the flash light is short, the rising and falling period of the surface temperature of the semiconductor wafer W is also short, and when the length of the emission waveform is long, the rising and falling period of the surface temperature of the semiconductor wafer W is also long. In the present embodiment, since the data collection cycle is variable according to the length of the emission waveform of the flash light, even if the rising and falling period of the surface temperature of the semiconductor wafer W changes due to the length of the emission waveform, The temperature change can be included in the temperature profile with a fixed number of data points until the surface temperature rises and falls through the highest temperature. That is, a temperature profile can be appropriately created regardless of the temperature rising time of the semiconductor wafer W.

  In the present embodiment, the cycle determination unit 35 determines the data collection cycle based on the length of the emission waveform of the flash light based on the conversion table. Therefore, it is possible to prevent the operator from changing the data collection cycle.

Furthermore, in the present embodiment, collection is started from temperature data that is a predetermined number or more before the temperature data when the surface temperature of the semiconductor wafer W reaches the threshold temperature _Tth higher than the preheating temperature T1. Therefore, the surface temperature of the semiconductor wafer W at the time when the irradiation of the flash light from the flash lamp FL is started can be reliably included in the temperature profile.

  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, the data collection cycle is changed to three stages based on the conversion table of FIG. 10, but the present invention is not limited to this, and the data collection period is changed according to the length of the emission waveform of the flash light. The collection cycle may be changed in two steps or four or more steps. Further, the numerical value of the data collection cycle is not limited to the example of FIG.

Further, in the above-described embodiment, the number of points of the temperature data for creating the temperature profile is 3000, but the present invention is not limited to this, and an appropriate number of points can be used. The number of points from the temperature data when the surface temperature of the semiconductor wafer W reaches the threshold temperature _Tth to the start point temperature data is not limited to 500 points, but may be an appropriate number.

  Further, in the above-described 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. . Further, the flash lamp FL is not limited to the xenon flash lamp, but 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 but may be any number.

  Further, in the above-described embodiment, the preheating of the semiconductor wafer W is performed using the filament type halogen lamp HL as a continuous lighting lamp that emits light continuously for 1 second or more. However, the present invention is not limited to this. The preliminary heating may be performed using a discharge type arc lamp (for example, a xenon arc lamp) as a continuous lighting lamp instead of the halogen lamp HL.

  The substrate to be processed by the heat treatment apparatus 1 is not limited to a semiconductor wafer, but 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, in the heat treatment apparatus 1, heat treatment of the high dielectric constant gate insulating film (High-k film), bonding of metal and silicon, or crystallization of polysilicon may be performed.

REFERENCE SIGNS LIST 1 heat treatment apparatus 3 control unit 4 halogen heating unit 5 flash heating unit 6 chamber 7 holding unit 10 transfer mechanism 20 lower radiation thermometer 25 upper radiation thermometer 29 infrared sensor 33 input unit 34 display unit 35 cycle determination unit 36, 107 storage Part 63 Upper chamber window 64 Lower chamber window 65 Heat treatment space 74 Susceptor 96 IGBT
101 High-speed radiation thermometer unit 105 Temperature conversion unit 106 Profile creation unit FL Flash lamp HL Halogen lamp W Semiconductor wafer

Claims (10)

A heat treatment method of heating the substrate by irradiating the substrate with flash light,
A flash light irradiating step of irradiating the surface of the substrate with flash light from a flash lamp,
A temperature measurement step of measuring the surface temperature of the substrate by a radiation thermometer at a preset data collection cycle,
Among the plurality of temperature data obtained in the temperature measurement step, a profile creation step of creating a temperature profile by extracting a certain number of temperature data before and after starting the flash light irradiation,
With
The heat treatment method, wherein the data collection cycle is variable. The heat treatment method according to claim 1,
In the profile creation step, temperature data obtained a predetermined number or more before the temperature data when the temperature measured by the radiation thermometer reaches a threshold is used as start point temperature data, and the constant number after the start point temperature data A heat treatment method characterized by extracting temperature data of the heat treatment. In the heat treatment method according to claim 1 or 2,
A heat treatment method, wherein the data collection cycle is determined according to a waveform of the flash light irradiated in the flash light irradiation step. The heat treatment method according to claim 3,
A heat treatment method, wherein the data collection cycle is determined based on a conversion table that associates a flash light waveform with a data collection cycle. In the heat treatment method according to claim 3 or 4,
The heat treatment method according to claim 1, wherein the longer the waveform of the flash light irradiated in the flash light irradiation step, the longer the data collection cycle. A heat treatment apparatus that heats the substrate by irradiating the substrate with flash light,
A chamber for accommodating the substrate;
A flash lamp that irradiates a flash light to the surface of the substrate housed in the chamber,
A radiation thermometer that receives infrared light emitted from the surface of the substrate and measures the temperature of the surface at a preset data collection cycle;
Among the plurality of temperature data measured and obtained by the radiation thermometer, a profile creation unit that creates a temperature profile by extracting a certain number of temperature data before and after the flash lamp starts irradiation of the flash light,
With
The heat treatment apparatus, wherein the data collection cycle is variable. The heat treatment apparatus according to claim 6,
The profile creation unit, as the start point temperature data temperature data acquired a predetermined number of times before the temperature data when the temperature measured by the radiation thermometer reaches a threshold, the constant number after the start point temperature data A heat treatment apparatus for extracting temperature data of a heat treatment. The heat treatment apparatus according to claim 6 or 7,
The heat treatment apparatus further comprising a cycle determination unit that determines the data collection cycle according to a waveform of the flash light emitted by the flash lamp. The heat treatment apparatus according to claim 8,
A storage unit that stores a conversion table that associates a flash light waveform with a data collection cycle,
The heat treatment apparatus, wherein the cycle determination unit determines the data collection cycle based on the corresponding table. In the heat treatment apparatus according to claim 8 or 9,
The heat treatment apparatus, wherein the cycle determination unit increases the data collection cycle as the waveform of the flash light emitted by the flash lamp becomes longer.

Images