JP7726838B2 - Temperature measurement method and heat treatment system - Google Patents

Description

The present invention relates to a temperature measurement method and a heat treatment system for measuring the temperature of a substrate, which changes when irradiated with flash light. Substrates to be treated include, for example, semiconductor wafers, substrates for liquid crystal displays, substrates for flat panel displays (FPDs), substrates for optical disks, substrates for magnetic disks, and substrates for solar cells.

Flash lamp annealing (FLA), a method of heating semiconductor wafers in an extremely short time, is attracting attention in the semiconductor device manufacturing process. Flash lamp annealing is a heat treatment technique that uses a xenon flash lamp (hereinafter, simply referred to as "flash lamp" means a xenon flash lamp) to irradiate the surface of a semiconductor wafer with a flash of light, thereby raising the temperature of only the surface of the semiconductor wafer in an extremely short time (a few milliseconds or less).

The spectral radiation distribution of a xenon flash lamp ranges from the ultraviolet to near-infrared range, with shorter wavelengths than conventional halogen lamps and roughly matching the fundamental absorption band of silicon semiconductor wafers. Therefore, when a semiconductor wafer is irradiated with flash light from a xenon flash lamp, little light is transmitted, making it possible to rapidly heat the semiconductor wafer. It has also been found that if the flash light is irradiated for an extremely short period of time, less than a few milliseconds, it is possible to selectively heat only the area near the surface of the semiconductor wafer.

Such flash lamp annealing is used in processes that require heating for an extremely short period of time, such as activating impurities implanted into semiconductor wafers. By irradiating the surface of a semiconductor wafer into which impurities have been implanted using ion implantation with a flash of light from a flash lamp, the surface of the semiconductor wafer can be heated to the activation temperature in an extremely short period of time, allowing only impurity activation to be carried out without deep diffusion of the impurities.

Wafer temperature management is important in any thermal treatment of semiconductor wafers, not just flash lamp annealing. In particular, with flash lamp annealing, only the surface vicinity of the semiconductor wafer is selectively heated, so it is important to measure the surface temperature of the semiconductor wafer, which changes rapidly when irradiated with flash light. The device characteristics of a semiconductor wafer after flash light irradiation are determined by the maximum temperature (peak temperature) reached on the wafer surface during flash light irradiation, so it is necessary to measure at least this maximum temperature. Patent Document 1 discloses a technique for accurately determining the emissivity of the surface of a semiconductor wafer and measuring the surface temperature of the semiconductor wafer during flash light irradiation using a radiation thermometer.

JP 2017-9450 A

However, in flash lamp annealing, extremely high-energy flash light is instantaneously irradiated onto the surface of a semiconductor wafer, causing the surface temperature of the semiconductor wafer to rise rapidly in an instant, while the backside temperature does not rise as much, resulting in a temperature gradient from the front to the backside. This causes sudden thermal expansion only near the front side of the semiconductor wafer, causing the semiconductor wafer to deform rapidly, warping with the top surface becoming convex. As a result, a phenomenon in which the semiconductor wafer vibrates on the susceptor that supports it has also been confirmed. Even if the emissivity of the surface of a semiconductor wafer is accurately determined using the technology disclosed in Patent Document 1, deformation of the semiconductor wafer, the target of temperature measurement, will cause fluctuations in the apparent emissivity as seen by the radiation thermometer, making it difficult to accurately measure the surface temperature of the semiconductor wafer when irradiated with flash light. Furthermore, because the warpage of the semiconductor wafer is not constant from process to process, this also reduces the reproducibility of temperature measurements.

The present invention was made in consideration of the above-mentioned problems, and aims to provide a temperature measurement method and heat treatment system that can accurately measure the temperature of a substrate when irradiated with flash light.

To solve the above problem, the invention of claim 1 is a temperature measurement method for measuring the temperature of a substrate that changes due to flash light irradiation, comprising: an irradiation step of irradiating the surface of the substrate with flash light from a flash lamp; an angle calculation step of calculating the measurement angle between the radiation thermometer and the substrate when the substrate is deformed by the irradiation of the flash light; an emissivity calculation step of calculating the emissivity of the substrate as seen from the radiation thermometer based on the measurement angle calculated in the angle calculation step; and a correction step of correcting the temperature of the substrate measured by the radiation thermometer based on the emissivity calculated in the emissivity calculation step.

Furthermore, the invention of claim 2 is a temperature measurement method according to the invention of claim 1, characterized in that in the angle calculation step, the measurement angle is calculated from a binary image obtained by binarizing an image of the substrate captured by a camera when irradiated with flash light.

Furthermore, the invention of claim 3 is characterized in that, in the temperature measurement method according to the invention of claim 2, in the angle calculation step, the camera captures images of the substrate at predetermined intervals, in the emissivity calculation step, the emissivity is calculated at the predetermined intervals, and in the correction step, the temperature of the substrate is corrected at the predetermined intervals.

Furthermore, the invention of claim 4 is characterized in that, in the temperature measurement method of the invention of claim 1, the emissivity calculation step calculates the emissivity from a table showing the correlation between measurement angle and emissivity.

Furthermore, the invention of claim 5 is a temperature measurement method according to the invention of claim 1, characterized in that in the angle calculation step, the measurement angle is calculated based on the warpage state of the substrate obtained from a simulation in which processing conditions are set as input parameters for a model.

The invention of claim 6 is a heat treatment system that heats a substrate by irradiating the substrate with a flash of light, comprising: a chamber that accommodates the substrate; a holder that holds the substrate in the chamber; a flash lamp that irradiates the substrate held in the holder with a flash of light; a radiation thermometer that measures the temperature of the substrate; an angle calculation unit that calculates the measurement angle between the radiation thermometer and the substrate when the substrate is deformed by the irradiation of the flash of light; an emissivity calculation unit that calculates the emissivity of the substrate as seen from the radiation thermometer based on the measurement angle calculated by the angle calculation unit; and a temperature correction unit that corrects the temperature of the substrate measured by the radiation thermometer based on the emissivity calculated by the emissivity calculation unit.

Furthermore, the invention of claim 7 is characterized in that, in the heat treatment system according to the invention of claim 6, it further comprises a camera that images the substrate held by the holder, and the angle calculation unit calculates the measurement angle from a binary image obtained by binarizing an image of the substrate captured by the camera when irradiated with flash light.

Furthermore, the invention of claim 8 is characterized in that, in the heat treatment system according to the invention of claim 7, the camera captures images of the substrate at predetermined intervals when irradiated with flash light, the emissivity calculation unit calculates the emissivity at the predetermined intervals, and the temperature correction unit corrects the temperature of the substrate at the predetermined intervals.

Furthermore, the invention of claim 9 is characterized in that the heat treatment system according to the invention of claim 6 further comprises a memory unit that stores a table showing the correlation between measurement angle and emissivity, and the emissivity calculation unit calculates the emissivity from the table.

Furthermore, the invention of claim 10 is characterized in that, in the heat treatment system of the invention of claim 6, the angle calculation unit calculates the measurement angle based on the warpage state of the substrate obtained from a simulation in which processing conditions are set as input parameters for a model.

According to the inventions of claims 1 to 5, the substrate temperature measured by the radiation thermometer is corrected based on the emissivity corresponding to the measurement angle between the radiation thermometer and the substrate. This means that the measured substrate temperature is corrected based on the emissivity corresponding to the measurement angle depending on the warpage of the substrate, making it possible to accurately measure the substrate temperature when irradiated with flash light.

According to the inventions of claims 6 to 10, the substrate temperature measured by the radiation thermometer is corrected based on the emissivity corresponding to the measurement angle between the radiation thermometer and the substrate. This means that the measured substrate temperature is corrected based on the emissivity corresponding to the measurement angle depending on the warpage state of the substrate, making it possible to accurately measure the substrate temperature when irradiated with flash light.

1 is a vertical cross-sectional view showing the configuration of a heat treatment apparatus for carrying out a temperature measuring method according to the present invention. FIG. 2 is a perspective view showing the overall appearance of the holding portion. FIG. FIG. 2 is a cross-sectional view of a susceptor. FIG. FIG. FIG. 2 is a plan view showing the arrangement of a plurality of halogen lamps. FIG. 2 is a block diagram showing the configuration of a control unit. 2 is a flowchart showing a procedure of a processing operation in the heat treatment apparatus of FIG. 1 . FIG. 10 is a diagram showing the measurement angle between the upper radiation thermometer and the semiconductor wafer. FIG. 10 is a diagram showing an example of a table defining the correlation between measurement angle and emissivity. FIG. 1 is a diagram showing an example of photographing a semiconductor wafer using two high-speed cameras. FIG. 10 is a diagram illustrating an example of a process for determining a warpage state using a simulation.

Embodiments of the present invention will be described in detail below with reference to the drawings. In the following, expressions indicating relative or absolute positional relationships (e.g., "in one direction," "along one direction," "parallel," "orthogonal," "center," "concentric," "coaxial," etc.) not only strictly represent the positional relationship, but also represent a state where there is a relative angular or distance displacement within a tolerance or a range where comparable functionality is achieved, unless otherwise specified. Furthermore, expressions indicating an equal state (e.g., "identical," "equal," "homogeneous," etc.) not only represent a state where there is a strict quantitative equivalence, but also represent a state where there is a difference where a tolerance or comparable functionality is achieved, unless otherwise specified. Furthermore, expressions indicating shape (e.g., "circular," "square," "cylindrical," etc.) not only represent a strict geometrical shape, but also represent a shape within a range where comparable functionality is achieved, and may, for example, have irregularities or chamfers. Furthermore, terms such as "comprise," "comprise," "include," "have," etc., regarding components, are not exclusive terms that exclude the presence of other components. Furthermore, the expression "at least one of A, B, and C" includes "A only," "B only," "C only," "any two of A, B, and C," and "all of A, B, and C."

Figure 1 is a vertical cross-sectional view showing the configuration of a heat treatment apparatus 1 for implementing a temperature measurement method according to the present invention. The heat treatment apparatus 1 in Figure 1 is a flash lamp annealing apparatus that heats a disk-shaped semiconductor wafer W as a substrate by irradiating the semiconductor wafer W with flash light. The size of the semiconductor wafer W to be processed is not particularly limited, but is, for example, 300 mm or 450 mm (300 mm in this embodiment). Note that in Figure 1 and the subsequent figures, the dimensions and number of various parts are exaggerated or simplified as necessary for ease of understanding.

The heat treatment apparatus 1 includes a chamber 6 that accommodates a semiconductor wafer W, a flash heating unit 5 that houses multiple flash lamps FL, and a halogen heating unit 4 that houses multiple halogen lamps HL. The flash heating unit 5 is provided above the chamber 6, and the halogen heating unit 4 is provided below it. The heat treatment apparatus 1 also includes a holding unit 7 inside the chamber 6 that holds the semiconductor wafer W in a horizontal position, and a transfer mechanism 10 that transfers the semiconductor wafer W between the holding unit 7 and the outside of the apparatus. The heat treatment apparatus 1 also includes a control unit 3 that controls the operating mechanisms provided in the halogen heating unit 4, flash heating unit 5, and chamber 6 to perform heat treatment on the semiconductor wafer W.

The chamber 6 is constructed by attaching quartz chamber windows to the top and bottom of a cylindrical chamber side portion 61. The chamber side portion 61 has a roughly cylindrical shape with openings at the top and bottom, with the upper opening attached and closed by an upper chamber window 63, and the lower opening attached and closed by a lower chamber window 64. The upper chamber window 63, which forms the ceiling of the chamber 6, is a disc-shaped member made 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, which forms the floor of the chamber 6, is also a disc-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 reflective ring 68 is attached to the upper part of the inner wall surface of the chamber side 61, and a reflective ring 69 is attached to the lower part. Both reflective rings 68, 69 are formed in an annular shape. The upper reflective ring 68 is attached by fitting it from the top side of the chamber side 61. On the other hand, the lower reflective ring 69 is attached by fitting it from the bottom side of the chamber side 61 and fastening it with screws (not shown). In other words, both reflective rings 68, 69 are detachably attached to the chamber side 61. The internal space of the chamber 6, i.e., the space surrounded by the upper chamber window 63, the lower chamber window 64, the chamber side 61, and the reflective rings 68, 69, is defined as the heat treatment space 65.

By attaching the reflective rings 68, 69 to the chamber side 61, a recess 62 is formed on the inner wall surface of the chamber 6. That is, the recess 62 is formed by the central portion of the inner wall surface of the chamber side 61 where the reflective rings 68, 69 are not attached, the lower end surface of the reflective ring 68, and the upper end surface of the reflective ring 69. The recess 62 is formed in an annular shape along the horizontal direction on the inner wall surface of the chamber 6, and surrounds the holder 7 that holds the semiconductor wafer W. The chamber side 61 and the reflective rings 68, 69 are made of a metal material (e.g., stainless steel) that has excellent strength and heat resistance.

Furthermore, a transfer opening (furnace port) 66 is formed in the chamber side 61 to allow semiconductor wafers W to be loaded and unloaded into and from the chamber 6. The transfer opening 66 can be opened and closed by a gate valve 185. The transfer opening 66 is connected to the outer circumferential surface of the recess 62. Therefore, when the gate valve 185 opens the transfer opening 66, semiconductor wafers W can be loaded into and unloaded from the heat treatment space 65 through the transfer opening 66 and the recess 62. Furthermore, when the gate valve 185 closes the transfer opening 66, the heat treatment space 65 within the chamber 6 becomes an airtight space.

Furthermore, through-holes 61a and 61b are drilled in the chamber side 61. The through-hole 61a is a cylindrical hole for guiding infrared light radiated from the upper surface of a semiconductor wafer W held on a susceptor 74 (described later) to the infrared sensor 29 of the upper radiation thermometer 25. Meanwhile, the through-hole 61b is a cylindrical hole for guiding infrared light radiated from the lower surface of the semiconductor wafer W to the infrared sensor 24 of the lower radiation thermometer 20. The through-holes 61a and 61b are inclined relative to the horizontal so that their penetration axes intersect with the main surface of the semiconductor wafer W held on the susceptor 74. A transparent window 26 made of calcium fluoride material that transmits infrared light in the wavelength range measurable by the upper radiation thermometer 25 is attached to the end of the through-hole 61a facing the heat treatment space 65. Additionally, a transparent window 21 made of barium fluoride material that transmits infrared light in the wavelength range measurable by the lower radiation thermometer 20 is attached to the end of the through hole 61b facing the heat treatment space 65.

Furthermore, gas supply holes 81 are formed in the upper part of the inner wall of the chamber 6 to supply processing gas to the heat treatment space 65. The gas supply holes 81 are formed at a position above the recess 62 and may be provided in the reflecting ring 68. The gas supply holes 81 are connected to a gas supply pipe 83 via a buffer space 82 formed in an annular shape inside the side wall of the chamber 6. The gas supply pipe 83 is connected to a processing gas supply source 85. A valve 84 is inserted in the gas supply pipe 83. When the valve 84 is opened, processing gas is supplied from the processing gas supply source 85 to the buffer space 82. The processing gas that has flowed into the buffer space 82 spreads within the buffer space 82, which has a lower fluid resistance than the gas supply holes 81, and is then supplied from the gas supply holes 81 into the heat treatment space 65. The processing gas may be, for example, an inert gas such as nitrogen (N ₂ ), or a reactive gas such as hydrogen (H ₂ ) or ammonia (NH ₃ ), or a mixed gas of these (nitrogen gas in this embodiment).

Meanwhile, a gas exhaust hole 86 is formed in the lower part of the inner wall of the chamber 6 to exhaust gas from the heat treatment space 65. The gas exhaust hole 86 is formed below the recess 62 and may be provided in the reflecting ring 69. The gas exhaust hole 86 is 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 an exhaust unit 190. A valve 89 is inserted in the gas exhaust pipe 88. When the valve 89 is opened, gas from the heat treatment space 65 is exhausted from the gas exhaust hole 86 through the buffer space 87 to the gas exhaust pipe 88. The gas supply hole 81 and the gas exhaust hole 86 may be multiple holes provided around the circumference of the chamber 6, or may be slit-shaped. The process gas supply source 85 and the exhaust unit 190 may be mechanisms provided in the heat treatment apparatus 1 or may be utilities of the factory where the heat treatment apparatus 1 is installed.

A gas exhaust pipe 191 that exhausts gas from 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 section 190 via a valve 192. By opening the valve 192, gas from the chamber 6 is exhausted through the transfer opening 66.

Figure 2 is a perspective view showing the overall appearance of the holder 7. The holder 7 is composed of a base ring 71, a connecting portion 72, and a susceptor 74. The base ring 71, the connecting portion 72, and the susceptor 74 are all made of quartz. In other words, the entire holder 7 is made of quartz.

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

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

A guide ring 76 is installed around the periphery of the upper surface of the holding plate 75. The guide ring 76 is an annular member with an inner diameter larger than the diameter of the semiconductor wafer W. For example, if the diameter of the semiconductor wafer W is φ300 mm, the inner diameter of the guide ring 76 is φ320 mm. The inner periphery of the guide ring 76 has a tapered surface that widens upward from the holding plate 75. The guide ring 76 is made of quartz, the same material 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 with a separately machined pin or the like. Alternatively, the holding plate 75 and guide ring 76 may be machined as a single integrated member.

The area of the upper surface of the holding plate 75 that is inward of the guide ring 76 is a planar holding surface 75a that holds the semiconductor wafer W. A plurality of substrate support pins 77 are erected on the holding surface 75a of the holding plate 75. In this embodiment, a total of 12 substrate support pins 77 are erected every 30° along a circle concentric with the outer circumferential circle of the holding surface 75a (the inner circumferential circle of the guide ring 76). The diameter of the circle on which the 12 substrate support pins 77 are arranged (the distance between opposing substrate support pins 77) is smaller than the diameter of the semiconductor wafer W. If the diameter of the semiconductor wafer W is 300 mm, the diameter is 270 mm to 280 mm (270 mm in this embodiment). Each substrate support pin 77 is made of quartz. The plurality of substrate support pins 77 may be attached to the upper surface of the holding plate 75 by welding, or may be machined integrally with the holding plate 75.

Returning to Figure 2, the four connecting portions 72 erected on the base ring 71 are fixed to the peripheral edge of the holding plate 75 of the susceptor 74 by welding. In other words, the susceptor 74 and base ring 71 are fixedly connected by the connecting portions 72. The base ring 71 of the holding portion 7 is supported on the wall surface of the chamber 6, thereby mounting the holding portion 7 to the chamber 6. When the holding portion 7 is mounted to the chamber 6, the holding plate 75 of the susceptor 74 is in a horizontal position (a position in which the normal line coincides with the vertical direction). In other words, the holding surface 75a of the holding plate 75 is a horizontal plane.

The semiconductor wafer W loaded into the chamber 6 is placed and held in a horizontal position on the susceptor 74 of the holder 7 attached to the chamber 6. At this time, the semiconductor wafer W is supported by 12 substrate support pins 77 erected on the holding plate 75 and held on the susceptor 74. More precisely, the upper ends of the 12 substrate support pins 77 contact the underside of the semiconductor wafer W to support the semiconductor wafer W. Because the heights of the 12 substrate support pins 77 (the distance from the upper ends of the substrate support pins 77 to the holding surface 75a of the holding plate 75) are uniform, the semiconductor wafer W can be supported in a horizontal position by the 12 substrate support pins 77.

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

2 and 3, an opening 78 is formed in the holding plate 75 of the susceptor 74, penetrating vertically. The opening 78 is provided so that the lower radiation thermometer 20 can receive radiation (infrared light) emitted from the underside of the semiconductor wafer W. That is, the lower radiation thermometer 20 receives light emitted from the underside of the semiconductor wafer W through the opening 78 and a transparent window 21 attached to the through-hole 61b of the chamber side 61, thereby measuring the temperature of the semiconductor wafer W. Furthermore, the holding plate 75 of the susceptor 74 is formed with four through-holes 79 through which lift pins 12 of the transfer mechanism 10, described below, pass to transfer the semiconductor wafer W.

Figure 5 is a plan view of the transfer mechanism 10. Figure 6 is a side view of the transfer mechanism 10. The transfer mechanism 10 has two transfer arms 11. The transfer arms 11 are arc-shaped so as to fit roughly along the annular recess 62. Two lift pins 12 are erected on each transfer arm 11. The transfer arms 11 and the lift pins 12 are made of quartz. Each transfer arm 11 is rotatable by a horizontal movement mechanism 13. The horizontal movement mechanism 13 horizontally moves the pair of transfer arms 11 between a transfer operation position (solid line position in Figure 5) where the semiconductor wafer W is transferred to and from the holder 7, and a retracted position (double-dashed line position in Figure 5) where the pair of transfer arms 11 do not overlap the semiconductor wafer W held by the holder 7 in a plan view. The horizontal movement mechanism 13 may be one that rotates each transfer arm 11 using an individual motor, or one that uses a link mechanism to rotate a pair of transfer arms 11 in unison using a single motor.

The pair of transfer arms 11 are raised and lowered together with the horizontal movement mechanism 13 by the lifting mechanism 14. When the lifting mechanism 14 raises the pair of transfer arms 11 to the transfer operation position, a total of four lift pins 12 pass through the through holes 79 (see Figures 2 and 3) drilled in the susceptor 74, and the upper ends of the lift pins 12 protrude from the upper surface of the susceptor 74. Meanwhile, when the lifting mechanism 14 lowers the pair of transfer arms 11 to the transfer operation position and removes the lift pins 12 from the through holes 79, and the horizontal movement mechanism 13 moves the pair of transfer arms 11 apart, each transfer arm 11 moves to a retracted position. The retracted position of the pair of transfer arms 11 is directly above the base ring 71 of the holder 7. Because the base ring 71 is placed on the bottom surface of the recess 62, the retracted position of the transfer arms 11 is inside the recess 62. In addition, an exhaust mechanism (not shown) is also provided near the location where the drive unit of the transfer mechanism 10 (horizontal movement mechanism 13 and lifting mechanism 14) is provided, and is configured to exhaust the atmosphere around the drive unit of the transfer mechanism 10 to the outside of the chamber 6.

Returning to Figure 1, the flash heating unit 5, located above the chamber 6, is configured with a light source consisting of multiple (30 in this embodiment) xenon flash lamps FL inside a housing 51, and a reflector 52 arranged to cover the light source from above. A lamp light emission window 53 is also attached to the bottom of the housing 51 of the flash heating unit 5. The lamp light emission window 53, which forms the floor of the flash heating unit 5, is a plate-shaped quartz window made of quartz. By installing the flash heating unit 5 above the chamber 6, the lamp light emission window 53 faces the upper chamber window 63. The flash lamps FL irradiate flash light from above the chamber 6 into the heat treatment space 65 through the lamp light emission window 53 and the upper chamber window 63.

The multiple flash lamps FL are each a rod-shaped lamp with a long, cylindrical shape, and are arranged in a plane so that their longitudinal directions are parallel to each other along the main surface of the semiconductor wafer W held by the holder 7 (i.e., along the horizontal direction). Therefore, the plane formed by the arrangement of the flash lamps FL is also a horizontal plane.

A xenon flash lamp FL comprises a rod-shaped glass tube (discharge tube) filled with xenon gas and fitted with an anode and cathode connected to a capacitor at both ends, and a trigger electrode attached to the outer surface of the glass tube. Because xenon gas is an electrical insulator, electricity does not flow within the glass tube under normal conditions, even if a charge is stored in the capacitor. However, when a high voltage is applied to the trigger electrode, causing the insulation to break down, the electricity stored in the capacitor flows instantaneously within the glass tube, exciting xenon atoms or molecules and emitting light. Such a xenon flash lamp FL converts electrostatic energy previously stored in the capacitor into extremely short light pulses of 0.1 to 100 milliseconds, enabling it to emit extremely intense light compared to continuous light sources such as halogen lamps HL. In other words, a flash lamp FL is a pulsed lamp that emits light instantaneously for an extremely short period of time, less than one second. The light emission time of the flash lamp FL can be adjusted by the coil constant of the lamp power supply that supplies power to the flash lamp FL.

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

The halogen heating unit 4, located below the chamber 6, has multiple (40 in this embodiment) halogen lamps HL built into the inside of the housing 41. The halogen heating unit 4 heats the semiconductor wafer W by irradiating light from the multiple halogen lamps HL from below the chamber 6 through the lower chamber window 64 into the heat treatment space 65.

Figure 7 is a plan view showing the arrangement of multiple halogen lamps HL. 40 halogen lamps HL are arranged in two rows, upper and lower. 20 halogen lamps HL are arranged in the upper row, closer to the holder 7, and 20 halogen lamps HL are also arranged in the lower row, which is farther from the holder 7 than the upper row. Each halogen lamp HL is a rod-shaped lamp with a long, cylindrical shape. In both the upper and lower rows, the 20 halogen lamps HL are arranged so that their longitudinal directions are parallel to each other along the main surface of the semiconductor wafer W held in the holder 7 (i.e., along the horizontal direction). Therefore, the plane formed by the arrangement of the halogen lamps HL in both the upper and lower rows is a horizontal plane.

Furthermore, as shown in FIG. 7, the halogen lamps HL are arranged more densely in the area facing the periphery of the semiconductor wafer W held by the holder 7 on both the upper and lower tiers than in the area facing the center of the semiconductor wafer W. In other words, on both the upper and lower tiers, the halogen lamps HL are arranged at a shorter pitch in the periphery of the lamp arrangement than in the center. This allows a greater amount of light to be irradiated onto the periphery of the semiconductor wafer W, where temperature drops are likely to occur during heating due to light irradiation from the halogen heating unit 4.

The lamp group consisting of the halogen lamps HL on the upper row and the lamp group consisting of the halogen lamps HL on the lower row are arranged so that they intersect in a grid pattern. In other words, a total of 40 halogen lamps HL are arranged so that the longitudinal direction of the 20 halogen lamps HL arranged on the upper row and the longitudinal direction of the 20 halogen lamps HL arranged on the lower row are perpendicular to each other.

Halogen lamps HL are filament-type light sources that emit light by passing electricity through a filament placed inside a glass tube, causing it to incandescent. The glass tube is filled with an inert gas, such as nitrogen or argon, to which trace amounts of halogen elements (iodine, bromine, etc.) have been added. The introduction of halogen elements makes it possible to set the filament temperature at a high temperature while preventing filament breakage. Therefore, halogen lamps HL have the characteristics of a longer lifespan than standard incandescent light bulbs and the ability to continuously emit strong light. In other words, halogen lamps HL are continuous lighting lamps that emit light continuously for at least one second. Furthermore, because halogen lamps HL are rod-shaped, they have a long lifespan, and by arranging them horizontally, they achieve excellent radiation efficiency toward the semiconductor wafer W above.

A reflector 43 is also provided below the two-tiered halogen lamps HL within the housing 41 of the halogen heating unit 4 (Figure 1). The reflector 43 reflects the light emitted from the multiple halogen lamps HL toward the heat treatment space 65.

As shown in FIG. 1, the chamber 6 is equipped with two radiation thermometers (pyrometers in this embodiment): an upper radiation thermometer 25 and a lower radiation thermometer 20. The upper radiation thermometer 25 is installed diagonally above the semiconductor wafer W held on the susceptor 74 and receives infrared light emitted from the top surface of the semiconductor wafer W to measure the temperature of the top surface. The infrared sensor 29 of the upper radiation thermometer 25 is equipped with an InSb (indium antimonide) optical element to respond to the sudden temperature change on the top surface of the semiconductor wafer W at the moment the flash light is irradiated. Meanwhile, the lower radiation thermometer 20 is installed diagonally below the semiconductor wafer W held on the susceptor 74 and receives infrared light emitted from the bottom surface of the semiconductor wafer W to measure the temperature of the bottom surface.

A high-speed camera 95 is also provided in the chamber 6. The high-speed camera 95 is located to the side of the susceptor 74 installed in the chamber 6, and photographs the semiconductor wafer W held on the susceptor 74 from the side. The photographing pitch of the high-speed camera 95 is set to any value between 10 microseconds (100,000 fps) and 1,000 microseconds (1,000 fps). While the high-speed camera 95 is shown in the transport opening 66 for convenience of illustration in FIG. 1, in reality the high-speed camera 95 is not located in the transport opening 66 but in a position that does not interfere with the loading and unloading of the semiconductor wafer W or with temperature measurement by a radiation thermometer.

The control unit 3 controls the various operating mechanisms provided in the heat treatment device 1. Figure 8 is a block diagram showing the configuration of the control unit 3. The hardware configuration of the control unit 3 is similar to that of a typical computer. That is, the control unit 3 includes a CPU, which is a circuit that performs various arithmetic processing, a ROM, which is a read-only memory that stores basic programs, a RAM, which is a readable and writable memory that stores various information, and a storage unit 34 (e.g., a magnetic disk) that stores control software, data, etc. Processing in the heat treatment device 1 progresses as the CPU of the control unit 3 executes a predetermined processing program.

The control unit 3 includes an angle calculation unit 31, an emissivity calculation unit 32, and a temperature correction unit 33. Each of the angle calculation unit 31, the emissivity calculation unit 32, and the temperature correction unit 33 is a functional processing unit realized by the CPU of the control unit 3 executing a predetermined processing program. The processing details of the angle calculation unit 31, the emissivity calculation unit 32, and the temperature correction unit 33 will be described further below. In addition, the memory unit 34 of the control unit 3 stores a table 35 (Figure 11) that shows the correlation between the measurement angle of the upper radiation thermometer 25 and the apparent emissivity of the semiconductor wafer W.

The control unit 3 is electrically connected to elements such as the high-speed camera 95. The control unit 3 receives image data captured by the high-speed camera 95 and performs predetermined image processing on the image. The control unit 3 also controls the output of the halogen lamp HL and the operation of the transfer mechanism 10.

The control unit 3 is also connected to a display unit 37 and an input unit 36. The display unit 37 and input unit 36 function as a user interface for the heat treatment device 1. The control unit 3 displays various information on the display unit 37. An operator of the heat treatment device 1 can input various commands and parameters from the input unit 36 while checking the information displayed on the display unit 37. The input unit 36 can be, for example, a keyboard or a mouse. The display unit 37 can be, for example, a liquid crystal display. In this embodiment, the display unit 37 and input unit 36 are both implemented as liquid crystal touch panels provided on the outer wall of the heat treatment device 1, providing both functions.

In addition to the above configuration, the heat treatment apparatus 1 is equipped with various cooling structures to prevent excessive temperature increases in the halogen heating unit 4, flash heating unit 5, and chamber 6 due to the thermal energy generated by the halogen lamps HL and flash lamps FL during heat treatment of the semiconductor wafer W. For example, a water-cooled pipe (not shown) is provided in the wall of the chamber 6. The halogen heating unit 4 and flash heating unit 5 also have an air-cooled structure that creates a gas flow inside to remove 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 upper chamber window 63.

Next, the processing operations of the heat treatment apparatus 1 having the above configuration will be described. Figure 9 is a flowchart showing the procedure of the processing operations of the heat treatment apparatus 1. The processing procedures of the heat treatment apparatus 1 described below proceed as the control unit 3 controls each operating mechanism of the heat treatment apparatus 1.

First, the air supply valve 84 is opened, and the exhaust valves 89 and 192 are also opened to start supplying and exhausting air to and from the chamber 6. When the valve 84 is opened, nitrogen gas is supplied to the heat treatment space 65 through the gas supply hole 81. When the valve 89 is opened, the gas inside the chamber 6 is exhausted through the gas exhaust hole 86. As a result, the nitrogen gas supplied from the top of the heat treatment space 65 inside the chamber 6 flows downward and is exhausted from the bottom of the heat treatment space 65.

In addition, by opening the valve 192, the gas inside the chamber 6 is also exhausted from the transport opening 66. Furthermore, an exhaust mechanism (not shown) also exhausts the atmosphere around the drive unit of the transfer mechanism 10. During the heat treatment of the semiconductor wafer W in the heat treatment apparatus 1, nitrogen gas is continuously supplied to the heat treatment space 65, and the supply amount is changed as appropriate depending on the treatment process.

Next, the gate valve 185 is opened to open the transport opening 66, and a semiconductor wafer W to be processed is loaded into the heat treatment space 65 in the chamber 6 through the transport opening 66 by a transport robot external to the apparatus (step S1). At this time, there is a risk that the atmosphere outside the apparatus may be drawn in as the semiconductor wafer W is loaded, but because nitrogen gas is continuously supplied to the chamber 6, the nitrogen gas flows out through the transport opening 66, minimizing the inclusion of such external atmosphere.

The semiconductor wafer W loaded by the transfer robot advances to a position directly above the holder 7 and stops there. 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, causing the lift pins 12 to pass through the through holes 79 and protrude from the upper surface of the holding plate 75 of the susceptor 74 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. The pair of transfer arms 11 then descend, transferring the semiconductor wafer W from the transfer mechanism 10 to the susceptor 74 of the holder 7, where it is held horizontally from below. The semiconductor wafer W is supported by multiple substrate support pins 77 erected on the holding plate 75 and held on the susceptor 74. The semiconductor wafer W is held on the holder 7 with its front surface, the surface to be processed, facing upward. A predetermined gap is formed between the back surface (the main surface opposite the front surface) of the semiconductor wafer W supported by the multiple substrate support pins 77 and the holding surface 75a of the holding plate 75. The pair of transfer arms 11, which have descended below the susceptor 74, are then retracted by the horizontal movement mechanism 13 to a retracted position, i.e., inside the recess 62.

After the semiconductor wafer W is held horizontally from below by the susceptor 74 of the holder 7, which is made of quartz, the 40 halogen lamps HL of the halogen heating unit 4 are simultaneously turned on to begin preheating (assisted heating) (step S2). The halogen light emitted from the halogen lamps HL passes through the lower chamber window 64 and susceptor 74, both of which are made of quartz, and is irradiated onto the underside of the semiconductor wafer W. The semiconductor wafer W is preheated by being irradiated with light from the halogen lamps HL, causing its temperature to rise. Note that the transfer arm 11 of the transfer mechanism 10 is retracted inside the recess 62 and does not interfere with heating by the halogen lamps HL.

The temperature of the semiconductor wafer W, which is heated by light irradiation from the halogen lamps HL, is measured by the lower radiation thermometer 20. 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 lamps HL while monitoring whether the temperature of the semiconductor wafer W, which is heated by light irradiation from the halogen lamps HL, has reached the predetermined preheating temperature T1. In other words, the control unit 3 feedback-controls the output of the halogen lamps HL based on the measurement value from the lower radiation thermometer 20 so that the temperature of the semiconductor wafer W reaches the preheating temperature T1. The lower radiation thermometer 20 is a temperature sensor for controlling the output of the halogen lamps HL.

After the temperature of the semiconductor wafer W reaches the preheating temperature T1, the control unit 3 temporarily maintains the semiconductor wafer W at that preheating temperature T1. Specifically, when the temperature of the semiconductor wafer W measured by the lower radiation thermometer 20 reaches the preheating temperature T1, the control unit 3 adjusts the output of the halogen lamps HL to maintain the temperature of the semiconductor wafer W at approximately the preheating temperature T1.

By performing preheating using the halogen lamps HL in this manner, the entire semiconductor wafer W is uniformly heated to the preheating temperature T1. During preheating using the halogen lamps HL, the temperature of the peripheral edge of the semiconductor wafer W, where heat dissipation is more likely, tends to be lower than that of the central area. However, the arrangement density of the halogen lamps HL in the halogen heating unit 4 is higher in the area facing the peripheral edge of the semiconductor wafer W than in the area facing the central area. As a result, a greater amount of light is irradiated onto the peripheral edge of the semiconductor wafer W, where heat dissipation is more likely, enabling a more uniform in-plane temperature distribution of the semiconductor wafer W during the preheating stage.

When a predetermined time has elapsed since the temperature of the semiconductor wafer W reached the preheating temperature T1, the flash lamps FL of the flash heating unit 5 irradiate the surface of the semiconductor wafer W held on the susceptor 74 with flash light (step S3). At this time, part of the flash light emitted from the flash lamps FL is directed directly into the chamber 6, while the other part is reflected by the reflector 52 before heading into the chamber 6. The semiconductor wafer W is flash-heated by the irradiation of these flash lights.

Flash heating is performed by irradiating a flash of light (flash of light) from the flash lamps FL, which allows the surface temperature of the semiconductor wafer W to rise in a short period of time. In other words, the flash of light irradiated from the flash lamps FL is an extremely short, intense flash of light with an irradiation time of approximately 0.1 milliseconds to 100 milliseconds, in which electrostatic energy previously stored in a capacitor is converted into an extremely short light pulse. The surface temperature of the semiconductor wafer W flash-heated by the irradiation of flash light from the flash lamps FL instantaneously rises to a processing temperature T2 of 1000°C or higher, and then rapidly drops.

When a flash of light with an extremely short irradiation time is applied, the temperature near the front surface of the semiconductor wafer W rises rapidly, while the temperature of the back surface does not rise significantly above the preheating temperature T1. As a result, sudden thermal expansion occurs only near the front surface of the semiconductor wafer W, causing the semiconductor wafer W to rapidly deform, warping with its upper surface convex. The high-speed camera 95 captures this behavior of the semiconductor wafer W when it is irradiated with flash light (step S4).

The high-speed camera 95 captures images of the behavior of the semiconductor wafer W from the side of the susceptor 74, i.e., from the horizontal direction. Therefore, when the semiconductor wafer W deforms so that its upper surface is warped and convex, the high-speed camera 95 can capture images of the warped state of the semiconductor wafer W. The high-speed camera 95 also captures images of the behavior of the semiconductor wafer W from at least the point at which the flash lamps FL begin to emit flash light. The high-speed camera 95 may also capture images of the semiconductor wafer W from an earlier point, for example, when the semiconductor wafer W is being preheated. The high-speed camera 95 also captures images of the semiconductor wafer W at a capture interval of 10 microseconds to 1000 microseconds (40 microseconds in this embodiment). Data on multiple images captured by the high-speed camera 95 is stored, for example, in the memory unit 34.

Meanwhile, the upper radiation thermometer 25 measures the surface temperature of the semiconductor wafer W being flash-heated (step S5). The upper radiation thermometer 25 measures the surface temperature of the semiconductor wafer W from diagonally above the semiconductor wafer W. The upper radiation thermometer 25 measures the surface temperature of the semiconductor wafer W at least from the point at which the flash lamps FL start irradiating the flash light. As with the high-speed camera 95 described above, the upper radiation thermometer 25 may be configured to measure the surface temperature of the semiconductor wafer W earlier, for example, when the semiconductor wafer W is being preheated. In other words, steps S4 and S5 may be performed before step S3.

Furthermore, it is preferable that the sampling pitch at which the upper radiation thermometer 25 measures the temperature be the same as the shooting pitch of the high-speed camera 95. Therefore, in this embodiment, the sampling pitch of the upper radiation thermometer 25 is 40 microseconds. With a sampling pitch of this order, the upper radiation thermometer 25 can appropriately measure the surface temperature of the semiconductor wafer W, which changes rapidly due to flash light irradiation. The temperature data measured by the upper radiation thermometer 25 is stored, for example, in the memory unit 34.

After the flash heating process is completed, the halogen lamps HL are extinguished after a predetermined time has elapsed. This causes the semiconductor wafer W to rapidly cool from the preheating temperature T1. The temperature of the semiconductor wafer W during cooling is measured by the lower radiation thermometer 20, and the measurement results are transmitted to the control unit 3. The control unit 3 monitors, based on the measurement results from the lower radiation thermometer 20, whether the temperature of the semiconductor wafer W has cooled to a predetermined temperature. After the temperature of the semiconductor wafer W has cooled to or below the predetermined temperature, the pair of transfer arms 11 of the transfer mechanism 10 again move horizontally from the retracted position to the transfer operation position and rise, causing the lift pins 12 to protrude from the top surface of the susceptor 74 and receive the post-heat-treatment semiconductor wafer W from the susceptor 74. Next, the transfer opening 66, which had been closed by the gate valve 185, is opened, and the semiconductor wafer W placed on the lift pins 12 is removed from the chamber 6 by a transfer robot external to the apparatus, completing the heat treatment of the semiconductor wafer W (step S6).

The surface temperature of the semiconductor wafer W, which rises and falls rapidly during flash light irradiation, is measured by the upper radiation thermometer 25. However, during flash light irradiation, the temperature rises rapidly only near the surface of the semiconductor wafer W, causing thermal expansion and deformation of the semiconductor wafer W. As a result, the apparent emissivity of the semiconductor wafer W as seen from the upper radiation thermometer 25 fluctuates, making it difficult to accurately measure the surface temperature of the semiconductor wafer W. Therefore, in this embodiment, steps S7 to S9 are performed to accurately measure the surface temperature of the semiconductor wafer W during flash light irradiation. Steps S7 to S9 are performed after the flash heating process of the semiconductor wafer W is completed and before the subsequent semiconductor wafer W is loaded into chamber 6.

First, the angle calculation unit 31 (Figure 8) calculates the measured angle between the upper pyrometer 25 and the semiconductor wafer W when the semiconductor wafer W is deformed by the irradiation of flash light (step S7). The memory unit 34 stores data on multiple images of the semiconductor wafer W captured by the high-speed camera 95 when the flash light was irradiated. The angle calculation unit 31 performs binarization processing on each image stored in the memory unit 34 to obtain a binary image. Binary processing is image processing that converts the target image into two gradations of black and white. By performing binarization processing on the image captured from the side of the semiconductor wafer W by the high-speed camera 95, the semiconductor wafer W is recognized as a line.

The angle calculation unit 31 performs further image processing on the obtained binary image to calculate the measurement angle between the upper radiation thermometer 25 and the semiconductor wafer W. Figure 10 is a diagram showing the measurement angle between the upper radiation thermometer 25 and the semiconductor wafer W. The two-dot chain line in Figure 10 represents the semiconductor wafer W held horizontally on the susceptor 74 before the flash light is irradiated. On the other hand, the solid line in Figure 10 represents the semiconductor wafer W deformed by the flash light irradiation. The measurement angle between the upper radiation thermometer 25 and the semiconductor wafer W is the angle between the optical axis of the infrared sensor 29 of the upper radiation thermometer 25 and the normal to the semiconductor wafer W. The measurement angle θ2 between the upper radiation thermometer 25 and the semiconductor wafer W deformed by the flash light irradiation is smaller than the measurement angle θ1 between the upper radiation thermometer 25 and the undeformed semiconductor wafer W before the flash light irradiation.

The angle calculation unit 31 uses image processing to determine the measurement angle between the upper radiation thermometer 25 and the semiconductor wafer W deformed by flash light irradiation. Depending on the sampling pitch of the temperature measurement by the upper radiation thermometer 25, the angle calculation unit 31 may calculate the measurement angle for all of the multiple images captured by the high-speed camera 95, or may extract a portion of the images and calculate the measurement angle. For example, as in this embodiment, if the sampling pitch of the upper radiation thermometer 25 is the same as the shooting pitch of the high-speed camera 95, the angle calculation unit 31 preferably calculates the measurement angle for all of the captured images. On the other hand, if the sampling pitch of the upper radiation thermometer 25 is longer than the shooting pitch of the high-speed camera 95, the angle calculation unit 31 preferably extracts a portion of the captured images and calculates the measurement angle. For example, if the sampling pitch of the upper radiation thermometer 25 is 40 microseconds and the shooting pitch of the high-speed camera 95 is 10 milliseconds, the angle calculation unit 31 only needs to extract one out of every four captured images and calculate the measurement angle.

Next, the emissivity calculation unit 32 calculates the apparent emissivity of the semiconductor wafer W as seen from the upper radiation thermometer 25 based on the measurement angle calculated by the angle calculation unit 31 (step S8). The apparent emissivity of the surface of the semiconductor wafer W is a parameter that varies depending on the measurement angle between the upper radiation thermometer 25 and the semiconductor wafer W. The correlation between the apparent emissivity of the surface of the semiconductor wafer W and the measurement angle between the upper radiation thermometer 25 and the semiconductor wafer W is determined in advance by experiment, simulation, etc., and stored in the memory unit 34 as table 35. Figure 11 shows an example of table 35 that specifies the correlation between measurement angle and emissivity.

The emissivity calculation unit 32 uses table 35 to determine the emissivity of the semiconductor wafer W corresponding to the measurement angle calculated in step S7. The emissivity determined in this manner by the emissivity calculation unit 32 is the apparent emissivity of the surface of the semiconductor wafer W as seen from the upper radiation thermometer 25 at the above measurement angle.

Next, the temperature correction unit 33 corrects the temperature of the semiconductor wafer W measured by the upper radiation thermometer 25 based on the apparent emissivity of the semiconductor wafer W calculated by the emissivity calculation unit 32 (step S9). When the upper radiation thermometer 25 measures the surface temperature of the flash-heated semiconductor wafer W in step S5, an appropriate value of the emissivity of the semiconductor wafer W (e.g., the emissivity when the semiconductor wafer W is not deformed) is set in the upper radiation thermometer 25. However, there is a difference between the set emissivity and the apparent emissivity of the semiconductor wafer W that deforms due to flash light irradiation, and this difference causes an error in the temperature measurement. For this reason, in this embodiment, the temperature measured by the upper radiation thermometer 25 is corrected based on the accurate apparent emissivity of the deformed semiconductor wafer W. Specifically, the emissivity set in the upper radiation thermometer 25 is replaced with the apparent emissivity of the semiconductor wafer W calculated in step S8, and the temperature measured by the upper radiation thermometer 25 is corrected by performing a calculation process to calculate the temperature of the semiconductor wafer W.

In this embodiment, the behavior of the semiconductor wafer W, which rapidly deforms when irradiated with flash light, is captured at predetermined intervals (40 microseconds in this embodiment) using a high-speed camera 95 to obtain multiple images. The angle calculation unit 31 calculates the measurement angle between the upper radiation thermometer 25 and the semiconductor wafer W for each predetermined interval from the multiple images. The emissivity calculation unit 32 then calculates the apparent emissivity of the semiconductor wafer W as viewed from the upper radiation thermometer 25 at each predetermined interval from the table 35 based on the measurement angle. Furthermore, the temperature correction unit 33 corrects the temperature of the semiconductor wafer W measured by the upper radiation thermometer 25 at each predetermined interval based on the calculated emissivity. In this way, even when the semiconductor wafer W rapidly deforms when irradiated with flash light, the measured temperature of the semiconductor wafer W is corrected based on the emissivity corresponding to the measurement angle depending on the warpage of the semiconductor wafer W, thereby enabling accurate measurement of the temperature of the semiconductor wafer W when irradiated with flash light.

While the above describes an embodiment of the present invention, various modifications other than those described above are possible without departing from the spirit of the present invention. For example, in step S4 of FIG. 9, multiple high-speed cameras may be used to capture images of the behavior of the semiconductor wafer W when flash light is applied. FIG. 12 is a diagram showing an example in which the semiconductor wafer W is photographed by two high-speed cameras. In the example of FIG. 12, a first high-speed camera 95a and a second high-speed camera 95b photograph the behavior of the semiconductor wafer W from the side of the susceptor 74, spaced 90° from each other. This allows for more accurate capture of the warpage of the semiconductor wafer W when flash light is applied, thereby enabling more accurate calculation of the measurement angle between the upper pyrometer 25 and the semiconductor wafer W. Note that the number of high-speed cameras may be three or more. While the use of more high-speed cameras allows for more accurate capture of the warpage of the semiconductor wafer W, the subsequent image processing becomes more complex and the installation costs of the high-speed cameras also increase.

In the above embodiment, the warpage of the semiconductor wafer W was measured by capturing images using a high-speed camera 95. However, this may also be determined by simulation. FIG. 13 illustrates an example of a process for determining the warpage using simulation. When using simulation, a model is created in advance that derives results such as the temperature distribution of the semiconductor wafer W when various processing conditions in the heat treatment apparatus 1 are input. Machine learning may also be used to create the model. Then, by setting the processing conditions for the semiconductor wafer W to be processed (e.g., the lamp power of the halogen lamps HL used for preheating, the charging voltage of the capacitor supplying power to the flash lamps FL, etc.) as input parameters to the model, the in-plane temperature distribution of the semiconductor wafer W during flash light irradiation can be obtained as an output. Once the in-plane temperature distribution of the semiconductor wafer W is obtained, the warpage of the semiconductor wafer W during flash light irradiation can be determined from the obtained in-plane temperature distribution. The model that outputs the in-plane temperature distribution of the semiconductor wafer W and the model that outputs the warpage may be separate, or they may be incorporated into a single model.

If the warpage state of the semiconductor wafer W when irradiated with flash light can be obtained through a simulation using a model, the measurement angle between the upper radiation thermometer 25 and the semiconductor wafer W can be calculated from that. Next, as in the above embodiment, the apparent emissivity of the semiconductor wafer W as seen from the upper radiation thermometer 25 is calculated based on the calculated measurement angle. The temperature of the semiconductor wafer W measured by the upper radiation thermometer 25 is then corrected based on the calculated apparent emissivity of the semiconductor wafer W. In this way, as in the above embodiment, the measured temperature of the semiconductor wafer W is corrected based on the emissivity corresponding to the measurement angle depending on the warpage state of the semiconductor wafer W, and therefore the temperature of the semiconductor wafer W when irradiated with flash light can be accurately measured.

Simulations using the above-described model may be performed by the control unit 3 of the heat treatment apparatus 1, or may be executed by a computer system separate from the heat treatment apparatus 1. Furthermore, the angle calculation unit 31, emissivity calculation unit 32, and temperature correction unit 33 of the above embodiment are not limited to being provided in the control unit 3, but may also be implemented in a computer system separate from the heat treatment apparatus 1. The computer system and the heat treatment apparatus 1 constitute a heat treatment system.

In addition, while in the above embodiment the surface temperature of the semiconductor wafer W measured by the upper radiation thermometer 25 was corrected, it is also possible to correct the back surface temperature of the semiconductor wafer W measured by the lower radiation thermometer 20 instead. In this case, as in the above embodiment, the measurement angle between the lower radiation thermometer 20 and the semiconductor wafer W is calculated from the warpage state of the semiconductor wafer W when irradiated with flash light, the emissivity corresponding to that measurement angle is found, and the back surface temperature of the semiconductor wafer W measured by the lower radiation thermometer 20 is corrected based on the found emissivity.

In addition, in the above embodiment, steps S7 to S9 are performed after the flash heating process of the semiconductor wafer W is completed. However, if sufficiently fast calculation processing is possible, it is also possible to determine the emissivity corresponding to the measurement angle depending on the warpage state of the semiconductor wafer W, and immediately set that emissivity in the upper radiation thermometer 25 to measure the temperature of the semiconductor wafer W. In this way, it is possible to perform real-time temperature measurement that takes into account the warpage state of the semiconductor wafer W, and to accurately measure the temperature of the semiconductor wafer W when irradiated with flash light.

In addition, in the above embodiment, the flash heating unit 5 is equipped with 30 flash lamps FL, but this is not limited to this and the number of flash lamps FL can be any number. Furthermore, the flash lamps FL are not limited to xenon flash lamps and may be krypton flash lamps. Furthermore, the number of halogen lamps HL equipped in the halogen heating unit 4 is not limited to 40 and can be any number.

In addition, in the above embodiment, the semiconductor wafer W was preheated using a filament-type halogen lamp HL as a continuously lit lamp that emits light continuously for one second or more. However, this is not limited to this, and the preheating process may be performed using a discharge arc lamp (e.g., a xenon arc lamp) or an LED lamp as a continuously lit lamp instead of the halogen lamp HL.

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 31 Angle calculation unit 32 Emissivity calculation unit 33 Temperature correction unit 34 Memory unit 35 Table 63 Upper chamber window 64 Lower chamber window 65 Heat treatment space 74 Susceptor 95 High-speed camera FL Flash lamp HL Halogen lamp W Semiconductor wafer

Claims (10)

A temperature measurement method for measuring a temperature of a substrate that changes due to flash light irradiation, comprising:
an irradiation step of irradiating a surface of the substrate with flash light from a flash lamp;
an angle calculation step of calculating a measurement angle between the radiation thermometer and the substrate when the substrate is deformed by irradiation with flash light;
an emissivity calculation step of calculating the emissivity of the substrate as seen from the radiation thermometer based on the measurement angle calculated in the angle calculation step;
a correction step of correcting the temperature of the substrate measured by the radiation thermometer based on the emissivity calculated in the emissivity calculation step;
A temperature measurement method comprising: 2. The temperature measurement method according to claim 1,
A temperature measuring method characterized in that in the angle calculation step, the measurement angle is calculated from a binary image obtained by binarizing an image of the substrate taken by a camera when irradiated with flash light. 3. The temperature measurement method according to claim 2,
In the angle calculation step, the camera captures images of the substrate at predetermined intervals,
In the emissivity calculation step, the emissivity is calculated at each predetermined interval,
The temperature measuring method, wherein the correction step corrects the temperature of the substrate at each predetermined interval. 2. The temperature measurement method according to claim 1,
The temperature measuring method according to claim 1, wherein the emissivity calculation step calculates the emissivity from a table showing the correlation between the measurement angle and the emissivity. 2. The temperature measurement method according to claim 1,
A temperature measuring method characterized in that in the angle calculation step, the measurement angle is calculated based on the warpage state of the substrate obtained from a simulation in which processing conditions are set as input parameters for a model. A thermal processing system that heats a substrate by irradiating the substrate with flash light, comprising:
a chamber for housing the substrate;
a holder that holds the substrate in the chamber;
a flash lamp that irradiates the substrate held by the holder with a flash of light;
a radiation thermometer for measuring the temperature of the substrate;
an angle calculation unit that calculates a measurement angle between the radiation thermometer and the substrate when the substrate is deformed by irradiation with flash light;
an emissivity calculation unit that calculates the emissivity of the substrate as seen from the radiation thermometer based on the measurement angle calculated by the angle calculation unit;
a temperature correction unit that corrects the temperature of the substrate measured by the radiation thermometer based on the emissivity calculated by the emissivity calculation unit;
A heat treatment system comprising: 7. The heat treatment system of claim 6,
further comprising a camera that captures an image of the substrate held by the holder;
The heat treatment system is characterized in that the angle calculation unit calculates the measurement angle from a binary image obtained by binarizing an image of the substrate captured by the camera when irradiated with flash light. 8. The heat treatment system of claim 7,
the camera captures images of the substrate at predetermined intervals while irradiated with flash light;
the emissivity calculation unit calculates the emissivity at each predetermined interval,
The thermal processing system is characterized in that the temperature correction unit corrects the temperature of the substrate at the predetermined intervals. 7. The heat treatment system of claim 6,
further comprising a storage unit that stores a table showing the correlation between the measurement angle and the emissivity;
The heat treatment system is characterized in that the emissivity calculation unit calculates the emissivity from the table. 7. The heat treatment system of claim 6,
The heat treatment system is characterized in that the angle calculation unit calculates the measurement angle based on a warpage state of the substrate obtained from a simulation in which processing conditions are set as input parameters for a model.