Temperature measuring method and heat treatment apparatus

Abstract

To provide a temperature measuring method and a heat treatment device capable of measuring a temperature of a substrate with high accuracy by accurately separating a component of disturbance light incident on a radiation thermometer.SOLUTION: The temperature of the semiconductor wafer held by the susceptor in the chamber is measured by a radiation thermometer. The radiation thermometer receives not only light emitted from the semiconductor wafer but also ambient light emitted from the lower chamber window, the susceptor, and the like. A low-frequency signal having a frequency lower than a thermal response of a semiconductor wafer during light irradiation is extracted by a low-pass filter from a detection signal output from a radiation thermometer receiving radiation light including a disturbance component. By performing correction by multiplying the low-frequency signal by the correction coefficient, a disturbance signal of only a component derived from disturbance light incident on the radiation thermometer is acquired. The temperature of the semiconductor wafer is calculated based on a signal obtained by subtracting the disturbance signal from the detection signal of the radiation thermometer.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a temperature measurement method for measuring the temperature of a substrate heated by light irradiation, and a heat treatment apparatus for heating a substrate by light irradiation. The substrate to be treated includes, for example, a semiconductor wafer, a substrate for a liquid crystal display device, a substrate for a flat panel display (FPD), a substrate for an optical disk, a substrate for a magnetic disk, or a substrate for a solar cell. [Background technology]

[0002] Flash lamp annealing (FLA), which heats semiconductor wafers in an extremely short time, is attracting attention in the semiconductor device manufacturing process.Flash lamp annealing is a heat treatment technology 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 flash light, thereby raising the temperature of only the surface of the semiconductor wafer in an extremely short time (a few milliseconds or less).

[0003] The spectral distribution of radiation from a xenon flash lamp is in the ultraviolet to near-infrared range, with a shorter wavelength than conventional halogen lamps and a wavelength that roughly matches 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.

[0004] Flash lamp annealing is used in processes that require heating for an extremely short period of time, such as activating impurities implanted in a semiconductor wafer. By irradiating the surface of a semiconductor wafer into which impurities have been implanted by ion implantation with a flash 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 the impurities to be activated without diffusing them deeply.

[0005] Wafer temperature management is important in semiconductor wafer thermal processing, not just flash lamp annealing. The temperature of a semiconductor wafer during thermal processing is typically measured using a non-contact radiation thermometer. Radiation thermometers are subject to ambient light, including infrared light emitted from the semiconductor wafer itself and from structures within the chamber, such as the susceptor and quartz window. This can lead to temperature measurement errors. In particular, because the front and back surfaces of a semiconductor wafer are mirror-like, the proportion of ambient light reflected by the wafer's front or back surface is relatively high compared to the radiation from the semiconductor wafer, which can easily lead to large temperature measurement errors. For this reason, Patent Document 1 discloses a technology for correcting semiconductor wafer temperature measurements using a radiation thermometer based on the temperatures of quartz structures, such as the susceptor and quartz window. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-087632 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the temperatures of the quartz window and other components constantly fluctuate during the heat treatment of semiconductor wafers. For example, when a halogen lamp is turned on to preheat the semiconductor wafer before flash light irradiation, the temperature of the quartz window rises, and when the halogen lamp is turned off, the temperature of the quartz window drops. Similarly, the temperature of the susceptor rises when the halogen lamp is turned on and drops when it is turned off. When the temperature of the quartz structure fluctuates in this way, the intensity of the ambient light incident on the radiation thermometer also fluctuates. However, with conventional methods, it has been difficult to separate only the ambient light component from the radiation light superimposed on the radiation thermometer. As a result, it has not been possible to reduce the measurement error of the radiation thermometer.

[0008] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a temperature measurement method and a heat treatment apparatus that can accurately separate the components of ambient light incident on a radiation thermometer and measure the temperature of a substrate with high accuracy. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, a first aspect of the present invention is a temperature measurement method for measuring the temperature of a substrate heated by light irradiation, comprising: a light receiving step of receiving, with a radiation thermometer, radiation light emitted from a substrate carried into a chamber; an extraction step of extracting, from a detection signal output from the radiation thermometer, a low-frequency signal having a frequency lower than the thermal response of the substrate when irradiated with light, using a low-pass filter that passes signals with frequencies lower than a predetermined cutoff frequency; a correction step of multiplying the low-frequency signal by a correction coefficient to obtain a disturbance signal derived from disturbance light incident on the radiation thermometer; and a temperature calculation step of calculating the temperature of the substrate based on a signal obtained by subtracting the disturbance signal from the detection signal.

[0010] In a second aspect, in the temperature measurement method according to the first aspect, the extracting step extracts the low-frequency signal from the detection signal using a plurality of low-pass filters having different cutoff frequencies.

[0011] In addition, a third aspect is a temperature measurement method according to the second aspect, wherein the plurality of low-pass filters include a first low-pass filter having a first cutoff frequency corresponding to a quartz window provided in the chamber and a second low-pass filter having a second cutoff frequency corresponding to a quartz susceptor that holds the substrate within the chamber.

[0012] In addition, a fourth aspect is a temperature measurement method according to the third aspect, wherein the extraction step acquires the low-frequency signal by summing components obtained by multiplying the outputs of the first low-pass filter and the second low-pass filter by a proportionality coefficient corresponding to the area ratio between the quartz window and the susceptor in the optical path incident on the radiation thermometer.

[0013] In addition, a fifth aspect is the temperature measurement method according to any one of the first to fourth aspects, wherein the low-pass filter is expressed by a second-order transfer function having a pole on the negative real axis.

[0014] In addition, a sixth aspect is the temperature measurement method according to any one of the first to fifth aspects, wherein the correction coefficient is the reflectance of the substrate.

[0015] In addition, a seventh aspect is the temperature measurement method according to the sixth aspect, wherein the reflectance of the substrate is measured sequentially during light irradiation.

[0016] In addition, an eighth aspect is a temperature measurement method according to any one of the first to fifth aspects, in which the correction coefficient is derived so that when a thermocouple-equipped substrate having a thermocouple attached thereto is irradiated with light to raise its temperature, the measured value obtained by measuring the temperature of the thermocouple-equipped substrate using the thermocouple matches the measured value obtained by measuring the temperature of the thermocouple-equipped substrate using the radiation thermometer.

[0017] In addition, a ninth aspect is a temperature measurement method according to any one of the first to fifth aspects, in which the correction coefficient is derived so that the measured value obtained by measuring the temperature of the substrate using the radiation thermometer while irradiating the substrate with light to raise the temperature matches the temperature of the substrate estimated from a dynamic characteristic model that mathematically expresses the temperature change of the substrate.

[0018] In addition, a tenth aspect is the temperature measurement method according to any one of the first to ninth aspects, wherein the plurality of substrates are irradiated with light by sequentially and repeatedly lighting the flash lamp and the continuous lighting lamp.

[0019] and a temperature calculation unit that calculates the temperature of the substrate based on a signal obtained by subtracting the disturbance signal from the detection signal. The temperature calculation unit calculates the temperature of the substrate based on a signal obtained by subtracting the disturbance signal from the detection signal. The temperature calculation unit calculates the temperature of the substrate based on a signal obtained by subtracting the disturbance signal from the detection signal. The temperature calculation unit calculates the temperature of the substrate based on a signal obtained by subtracting the disturbance signal from the detection signal. The temperature calculation unit calculates the temperature of the substrate based on a signal obtained by subtracting the disturbance signal from the detection signal. The temperature calculation unit calculates the temperature of the substrate based on a signal obtained by subtracting the disturbance signal from the detection signal. The temperature calculation unit calculates the temperature of the substrate based on a signal obtained by subtracting the disturbance signal from the detection signal.

[0020] In addition, a twelfth aspect is the heat treatment apparatus according to the eleventh aspect, wherein the low frequency signal is extracted from the detection signal by a plurality of low pass filters having different cutoff frequencies.

[0021] In a thirteenth aspect, in the heat treatment apparatus according to the twelfth aspect, the plurality of low-pass filters include a first low-pass filter having a first cutoff frequency corresponding to a quartz window provided in the chamber and a second low-pass filter having a second cutoff frequency corresponding to the susceptor.

[0022] In addition, in a fourteenth aspect, in the heat treatment apparatus according to the thirteenth aspect, the low-frequency signal is obtained by summing components obtained by multiplying the outputs of the first low-pass filter and the second low-pass filter by a proportional coefficient corresponding to the area ratio between the quartz window and the susceptor in the optical path incident on the radiation thermometer.

[0023] In addition, a fifteenth aspect is the heat treatment apparatus according to any one of the eleventh to fourteenth aspects, wherein the low-pass filter is expressed by a second-order transfer function having a pole on the negative real axis.

[0024] In a sixteenth aspect, in the heat treatment apparatus according to any one of the eleventh to fifteenth aspects, the correction coefficient is the reflectance of the substrate.

[0025] In a seventeenth aspect, in the heat treatment apparatus according to the sixteenth aspect, the reflectance of the substrate is measured successively during irradiation with light from the light irradiation unit.

[0026] In addition, an 18th aspect is a heat treatment apparatus according to any one of the 11th to 17th aspects, wherein the light irradiation unit includes a flash lamp and a continuous lighting lamp, and light irradiation is performed on a plurality of substrates by sequentially and repeatedly lighting the flash lamp and the continuous lighting lamp. [Effects of the Invention]

[0027] According to the temperature measurement methods of the first to tenth aspects, a low-frequency signal having a frequency lower than the thermal response of the substrate when irradiated with light is extracted from the detection signal output from the radiation thermometer using a low-pass filter, and a disturbance signal resulting from the disturbance light incident on the radiation thermometer is obtained by multiplying the low-frequency signal by a correction coefficient. The temperature of the substrate is calculated based on the signal obtained by subtracting the disturbance signal from the detection signal, so that the components of the disturbance light incident on the radiation thermometer can be accurately separated and the temperature of the substrate can be measured with high accuracy.

[0028] According to the heat treatment apparatuses of the eleventh to eighteenth aspects, a low-frequency signal having a frequency lower than the thermal response of the substrate when irradiated with light is extracted from a detection signal output from a radiation thermometer that receives radiation light emitted from the substrate, and a disturbance signal resulting from the disturbance light incident on the radiation thermometer is obtained by multiplying the low-frequency signal by a correction coefficient, and the temperature of the substrate is calculated based on a signal obtained by subtracting the disturbance signal from the detection signal, thereby making it possible to accurately separate the components of the disturbance light incident on the radiation thermometer and measure the temperature of the substrate with high accuracy. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a vertical cross-sectional view showing the configuration of a heat treatment apparatus according to the present invention. [Figure 2]FIG. 2 is a perspective view showing the overall appearance of the holding portion. [Figure 3] FIG. [Figure 4] FIG. 2 is a cross-sectional view of a susceptor. [Figure 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 2 is a plan view showing the arrangement of a plurality of halogen lamps. [Figure 8] FIG. 2 is a functional block diagram of a temperature measurement mechanism including a radiation thermometer. [Figure 9] 10 is a flowchart showing a procedure of a processing operation in a heat treatment apparatus. [Figure 10] 10 is a flowchart showing a procedure for measuring the temperature of a semiconductor wafer using a radiation thermometer. [Figure 11] FIG. 2 is a diagram schematically showing light incident on a radiation thermometer when a semiconductor wafer is heated by light irradiation from a halogen lamp. [Figure 12] FIG. 10 is a diagram illustrating the influence of ambient light on the temperature measurement of a radiation thermometer. [Figure 13] FIG. 4 is a Bode diagram showing frequency characteristics of the lower chamber window and the susceptor. [Figure 14] FIG. 10 is a diagram showing a schematic configuration of a heat treatment apparatus according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Hereinafter, 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 of relative angular or distance displacement within a tolerance or a range that provides equivalent functionality, unless otherwise specified. Furthermore, expressions indicating an equal state (e.g., "identical," "equal," "homogeneous," etc.) not only represent a state of strict quantitative equality but also represent a state of difference that provides a tolerance or equivalent functionality, unless otherwise specified. Furthermore, expressions indicating a shape (e.g., "circular," "square," "cylindrical," etc.) not only represent a geometrically strict shape but also represent a shape within a range that provides equivalent functionality, such as irregularities or chamfers, unless otherwise specified. Furthermore, expressions such as "comprise," "comprise," "include," "have," etc., regarding components, are not exclusive expressions 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."

[0031] First Embodiment FIG. 1 is a vertical cross-sectional view showing the configuration of a heat treatment apparatus 1 according to the present invention. The heat treatment apparatus 1 in FIG. 1 is a flash lamp annealing apparatus that heats a disk-shaped semiconductor wafer W as a substrate by irradiating the semiconductor wafer W with flash light. The size of the semiconductor wafer W to be treated is not particularly limited, but may be, for example, φ300 mm or φ450 mm. Note that in FIG. 1 and the subsequent figures, the dimensions and number of various parts are exaggerated or simplified as necessary for ease of understanding.

[0032] Heat treatment apparatus 1 includes a chamber 6 that accommodates a semiconductor wafer W, a flash heating unit 5 that incorporates multiple flash lamps FL, and a halogen heating unit 4 that incorporates multiple halogen lamps HL. The flash heating unit 5 is provided above chamber 6, and the halogen heating unit 4 is provided below. Heat treatment apparatus 1 also includes, inside chamber 6, a holder 7 that holds the semiconductor wafer W in a horizontal position, and a transfer mechanism 10 that transfers the semiconductor wafer W between the holder 7 and the outside of the apparatus. 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.

[0033] 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 an upper chamber window 63 attached to and closing the upper opening, and a lower chamber window 64 attached to and closing the lower opening. 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 the 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 the light from the halogen heating unit 4 into the chamber 6.

[0034] Furthermore, 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 upper side of the chamber side 61. On the other hand, the lower reflective ring 69 is attached by fitting it from the lower 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 a heat treatment space 65.

[0035] By attaching the reflecting rings 68, 69 to the chamber side portion 61, a recess 62 is formed on the inner wall surface of the chamber 6. That is, the recess 62 is formed by a central portion of the inner wall surface of the chamber side portion 61 where the reflecting rings 68, 69 are not attached, the lower end surface of the reflecting ring 68, and the upper end surface of the reflecting 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 portion 61 and the reflecting rings 68, 69 are made of a metal material (e.g., stainless steel) that has excellent strength and heat resistance.

[0036] Furthermore, a transfer opening (furnace port) 66 is formed in the chamber side portion 61, through which a semiconductor wafer W is loaded into and unloaded 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 peripheral surface of the recessed portion 62. Therefore, when the gate valve 185 opens the transfer opening 66, the semiconductor wafer W can be loaded into and unloaded from the heat treatment space 65 through the transfer opening 66 and the recessed portion 62. Furthermore, when the gate valve 185 closes the transfer opening 66, the heat treatment space 65 in the chamber 6 becomes an airtight space.

[0037] Furthermore, a through-hole 61a is formed in the chamber side portion 61. A radiation thermometer 20 is attached to the portion of the outer wall surface of the chamber side portion 61 where the through-hole 61a is provided. The through-hole 61a is a cylindrical hole for guiding infrared light emitted from the underside of a semiconductor wafer W held on a susceptor 74 (described later) to the radiation thermometer 20. The through-hole 61a is provided at an angle with respect to the horizontal direction so that the axis of the through-hole 61a intersects with the main surface of the semiconductor wafer W held on the susceptor 74. A transparent window 21 made of barium fluoride material that transmits infrared light in a wavelength range that can be measured by the radiation thermometer 20 is attached to the end of the through-hole 61a facing the heat treatment space 65.

[0038] 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 recessed portion 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 lower fluid resistance than the gas supply holes 81, and is 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 (N2), argon (Ar), or helium (He), or a reactive gas such as hydrogen (H2), ammonia (NH3), or a mixed gas of these.

[0039] 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, the gas in 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 provided in multiple numbers along the circumferential direction 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 a factory where the heat treatment apparatus 1 is installed.

[0040] 2 is a perspective view showing the overall appearance of the holder 7. The holder 7 is configured to include 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.

[0041] 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 a 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 FIG. 1). A plurality of connecting portions 72 (four in this embodiment) are erected on the upper surface of the base ring 71 along the circumferential direction of the annular shape. The connecting portions 72 are also quartz members, and are fixed to the base ring 71 by welding.

[0042] 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 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. That is, the holding plate 75 has a planar size larger than that of the semiconductor wafer W.

[0043] A guide ring 76 is installed on the periphery 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, 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 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 integrated member.

[0044] The area of ​​the upper surface of the holding plate 75 that is inside the guide ring 76 is a flat holding surface 75a that holds the semiconductor wafer W. A plurality of substrate support pins 77 are provided on the holding surface 75a of the holding plate 75. In this embodiment, a total of 12 substrate support pins 77 are provided at 30° intervals along a circumference 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 provided on the upper surface of the holding plate 75 by welding, or may be machined integrally with the holding plate 75.

[0045] Returning to FIG. 2, 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. That is, the susceptor 74 and the 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, and the holding portion 7 is thereby attached to the chamber 6. When the holding portion 7 is attached 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). That is, the holding surface 75a of the holding plate 75 is a horizontal plane.

[0046] The semiconductor wafer W carried 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 twelve substrate support pins 77 erected on a holding plate 75 and held on the susceptor 74. More precisely, the upper ends of the twelve substrate support pins 77 contact the underside of the semiconductor wafer W to support the semiconductor wafer W. The heights of the twelve 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, so the twelve substrate support pins 77 can support the semiconductor wafer W in a horizontal position.

[0047] Furthermore, 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 the semiconductor wafer W supported by the plurality of substrate support pins 77 from shifting in the horizontal direction.

[0048] 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 a radiation thermometer 20 can receive radiation (infrared light) emitted from the underside of the semiconductor wafer W. That is, the radiation thermometer 20 receives the light emitted from the underside of the semiconductor wafer W through the opening 78 and a transparent window 21 attached to the through-hole 61 a 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 a transfer mechanism 10 (described later) pass to transfer the semiconductor wafer W.

[0049] 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 arms 11 are arc-shaped so as to fit the generally annular recess 62. Two lift pins 12 are provided on each of the transfer arms 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 (position indicated by a solid line in FIG. 5) where the transfer arms 11 transfer the semiconductor wafer W to the holder 7 and a retracted position (position indicated by a two-dot chain line in FIG. 5) where the 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 conjunction with one another using a single motor.

[0050] Furthermore, 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 through holes 79 (see FIGS. 2 and 3 ) formed in the susceptor 74, and the upper ends of the lift pins 12 protrude from the upper surface of the susceptor 74. On the other hand, when the lifting mechanism 14 lowers the pair of transfer arms 11 to the transfer operation position to remove the lift pins 12 from the through holes 79, and the horizontal movement mechanism 13 moves the pair of transfer arms 11 so as to open, 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 part of the transfer mechanism 10 (horizontal movement mechanism 13 and lifting mechanism 14) is located, and is configured to exhaust the atmosphere around the drive part of the transfer mechanism 10 to the outside of the chamber 6.

[0051] Returning to FIG. 1 , the flash heating unit 5, which is provided above the chamber 6, is configured with a light source made up of multiple (30 in this embodiment) xenon flash lamps FL inside a housing 51, and a reflector 52 provided to cover the light source from above. A lamp light emission window 53 is attached to the bottom of the housing 51 of the flash heating unit 5. The lamp light emission window 53, 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 a 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.

[0052] The flash lamps FL are each a rod-shaped lamp having 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. The area in which the flash lamps FL are arranged is larger than the planar size of the semiconductor wafer W.

[0053] A xenon flash lamp FL comprises a cylindrical 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 the xenon atoms or molecules and emitting light. In such a xenon flash lamp FL, electrostatic energy previously stored in the capacitor is converted 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 adjusting the coil constant of the lamp power supply that supplies power to the flash lamp FL.

[0054] Furthermore, reflector 52 is provided above the multiple flash lamps FL so as to cover them entirely. The basic function of reflector 52 is to reflect the flash light emitted from the multiple flash lamps FL toward the heat treatment space 65. Reflector 52 is made of an aluminum alloy plate, and its surface (the surface facing the flash lamps FL) is roughened by blasting.

[0055] The halogen heating unit 4, which is provided below the chamber 6, has a plurality of halogen lamps HL (40 in this embodiment) built into the inside of the housing 41. The halogen heating unit 4 heats the semiconductor wafer W by irradiating light from the plurality of halogen lamps HL from below the chamber 6 through a lower chamber window 64 into a heat treatment space 65.

[0056] FIG. 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, which is 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 having 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 by 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.

[0057] 7, the halogen lamps HL are arranged more densely in the region facing the periphery of the semiconductor wafer W held by the holder 7 on both the upper and lower tiers than in the region facing the center of the semiconductor wafer W. That is, 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, which is prone to temperature drop during heating due to light irradiation from the halogen heating unit 4.

[0058] 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 as to intersect in a grid pattern. That is, a total of 40 halogen lamps HL are arranged so that the longitudinal direction of the 20 halogen lamps HL arranged on the upper row and the longitudinal direction of the 20 halogen lamps HL arranged on the lower row are perpendicular to each other.

[0059] A halogen lamp HL is a filament-type light source that emits 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, containing trace amounts of halogen elements (iodine, bromine, etc.). The introduction of halogen elements makes it possible to set the filament temperature at a high temperature while preventing filament breakage. Therefore, compared to standard incandescent light bulbs, halogen lamps HL have the characteristics of a longer lifespan and the ability to continuously emit strong light. In other words, halogen lamps HL are continuous 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.

[0060] Also, a reflector 43 is provided below the two-tiered halogen lamps HL inside the housing 41 of the halogen heating unit 4 (FIG. 1). The reflector 43 reflects the light emitted from the multiple halogen lamps HL toward the heat treatment space 65.

[0061] 1, the chamber 6 is provided with a radiation thermometer 20 as a temperature sensor for measuring the temperature of the semiconductor wafer W. The radiation thermometer 20 is provided diagonally below the semiconductor wafer W held on the susceptor 74. The radiation thermometer 20 receives infrared light radiated from the bottom surface of the semiconductor wafer W through an opening 78, which is a notch provided in the susceptor 74, and measures the temperature of the bottom surface.

[0062] 8 is a functional block diagram of a temperature measurement mechanism including a radiation thermometer 20. In addition to the radiation thermometer 20, the heat treatment apparatus 1 is provided with a signal conversion circuit 102, a first low-pass filter 111, a second low-pass filter 112, a synthesis unit 105, a correction unit 107, and a temperature calculation unit 108 as a mechanism for measuring the temperature of the semiconductor wafer W. These elements, such as the signal conversion circuit 102, may be provided in a dedicated temperature measurement unit attached to the radiation thermometer 20, or may be provided in, for example, the control unit 3.

[0063] The signal conversion circuit 102 converts the resistance change generated in the light receiving element of the radiation thermometer 20 into a current change and then a voltage change, and finally converts it into an easy-to-handle voltage signal and outputs it. The signal conversion circuit 102 is configured using, for example, an operational amplifier. The signal output from the signal conversion circuit 102 is treated as a detection signal output from the radiation thermometer 20 that has received the radiation. The detection signal is a signal based on the intensity of the radiation received by the radiation thermometer 20.

[0064] The first low-pass filter 111 and the second low-pass filter 112 are provided in parallel with the radiation thermometer 20. Both the first low-pass filter 111 and the second low-pass filter 112 are so-called low-pass filters (LPFs), which are filters that attenuate frequency components higher than a predetermined cutoff frequency (cutoff frequency) without attenuating frequency components lower than the cutoff frequency. In the first embodiment, the cutoff frequency of the first low-pass filter 111 is, for example, 1×10 -3 Hz, and the cutoff frequency of the second low-pass filter 112 is, for example, 2×10 -2 Hz. The functions of the first low-pass filter 111 and the second low-pass filter 112 will be described further below.

[0065] The combining unit 105 combines the signal output from the first low-pass filter 111 and the signal output from the second low-pass filter 112. The combining unit 105 adds up components obtained by multiplying both signals by a predetermined proportional coefficient. In other words, the combining unit 105 combines the weighted signals.

[0066] The correction unit 107 performs correction by multiplying the signal output from the combining unit 105 by a predetermined correction coefficient. The signal corrected by the correction unit 107 is a disturbance signal derived from external light incident on the radiation thermometer 20.

[0067] The temperature calculation unit 108 calculates the temperature of the semiconductor wafer W, which is the measurement target of the radiation thermometer 20 , based on the detection signal of the radiation thermometer 20 output from the signal conversion circuit 102 and the disturbance signal output from the correction unit 107 .

[0068] The control unit 3 controls the various operating mechanisms provided in the heat treatment device 1. The hardware configuration of the control unit 3 is similar to that of a general 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 (e.g., a magnetic disk or SSD) that stores control software, data, and the like. The CPU of the control unit 3 executes a predetermined processing program, causing the processing in the heat treatment device 1 to proceed.

[0069] In addition to the above configuration, the heat treatment apparatus 1 is equipped with various cooling structures to prevent excessive temperature rise 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.

[0070] Next, a description will be given of the processing operation in the heat treatment apparatus 1 having the above configuration. Fig. 9 is a flowchart showing the procedure of the processing operation in the heat treatment apparatus 1. The processing procedure of the heat treatment apparatus 1 described below progresses as the control unit 3 controls each operating mechanism of the heat treatment apparatus 1.

[0071] First, prior to processing of the semiconductor wafer W, the gas supply valve 84 is opened, and the exhaust valve 89 is also opened to start supplying and exhausting gas 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 upper part of the heat treatment space 65 inside the chamber 6 flows downward and is exhausted from the lower part of the heat treatment space 65.

[0072] Next, gate valve 185 is opened to open transfer opening 66, and a semiconductor wafer W to be processed is loaded into heat treatment space 65 in chamber 6 through transfer opening 66 by a transfer robot outside 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 since nitrogen gas is continuously supplied to chamber 6, the nitrogen gas flows out from transfer opening 66, making it possible to minimize the inclusion of such external atmosphere.

[0073] The semiconductor wafer W carried in 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 to a position higher than the upper ends of the substrate support pins 77.

[0074] 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. Then, the pair of transfer arms 11 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 a plurality of 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, which is the surface to be processed, 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, which have descended to below the susceptor 74, are retracted to a retracted position, i.e., inside the recess 62, by the horizontal movement mechanism 13.

[0075] After the semiconductor wafer W is held from below in a horizontal position 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 the 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, and its temperature rises. Note that the transfer arm 11 of the transfer mechanism 10 is retracted inside the recess 62, so it does not interfere with heating by the halogen lamps HL.

[0076] The temperature of the semiconductor wafer W, which is raised by the light irradiation from the halogen lamps HL, is measured by the radiation thermometer 20 (step S3). FIG.

[0077] Regardless of the temperature of the semiconductor wafer W, the radiation thermometer 20 receives radiant light (step S31). Fig. 11 is a diagram schematically showing light incident on the radiation thermometer 20 when the semiconductor wafer W is being heated by light irradiation from the halogen lamp HL. First, radiant light (infrared light) emitted from the bottom surface of the semiconductor wafer W being heated passes through the opening 78 of the susceptor 74 and enters the radiation thermometer 20.

[0078] Furthermore, although most of the light emitted from the halogen lamps HL passes through the quartz lower chamber window 64 and susceptor 74, a portion of the light is absorbed by the lower chamber window 64 and susceptor 74. The lower chamber window 64 and susceptor 74, which have absorbed some of the light emitted from the halogen lamps HL, rise to an appropriate temperature (a temperature between that of the semiconductor wafer W and room temperature). The susceptor 74 also rises in temperature due to thermal conduction and radiant heat from the heated semiconductor wafer W. The heated lower chamber window 64 and susceptor 74 emit infrared light of an intensity corresponding to their temperature. The radiated light emitted from the heated lower chamber window 64 passes through the openings 78 of the susceptor 74, is reflected by the mirror-finished underside of the semiconductor wafer W, and enters the radiation thermometer 20.

[0079] Furthermore, the radiation emitted from the heated susceptor 74 also enters the radiation thermometer 20. The radiation thermometer 20 measures the temperature of the semiconductor wafer W through an opening 78 provided in the susceptor 74, but typically the field of view of the radiation thermometer 20 is larger than the opening 78, and direct light from the susceptor 74 enters the radiation thermometer 20.

[0080] The light emitted from the lower chamber window 64 and the susceptor 74 and incident on the radiation thermometer 20 is disturbance light. In addition to the above, the disturbance light incident on the radiation thermometer 20 also includes light emitted from the upper chamber window 63 and transmitted through the semiconductor wafer W, and light emitted from the chamber side portion 61 of the chamber 6. However, the amount of light emitted from the upper chamber window 63 and transmitted through the semiconductor wafer W is significantly smaller than the amount of light incident on the radiation thermometer 20 from the lower chamber window 64 and the susceptor 74. For this reason, in this embodiment, the disturbance light incident on the radiation thermometer 20 is considered to be the light reflected from the lower chamber window 64 and the light directly from the susceptor 74. In particular, the light emitted from the lower chamber window 64 and reflected by the underside of the semiconductor wafer W is the dominant disturbance light incident on the radiation thermometer 20, as it has the largest relative amount of light.

[0081] Such disturbance light hinders accurate temperature measurement of the semiconductor wafer W by the radiation thermometer 20. FIG. 12 is a diagram showing the effect of disturbance light on the temperature measurement by the radiation thermometer 20. When the halogen lamp HL is turned on at time t0, the temperature of the semiconductor wafer W rises, and the temperature measurement value of the radiation thermometer 20 also rises. The temperatures of the lower chamber window 64, which is a quartz window, and the susceptor 74 also rise. However, as the time elapses after the halogen lamp HL is turned on, the deviation between the temperature measurement value of the radiation thermometer 20 and the actual temperature of the semiconductor wafer W increases. The accurate temperature of the semiconductor wafer W can be measured by, for example, attaching a thermocouple to the semiconductor wafer W.

[0082] 12 is caused by disturbance light incident on the radiation thermometer 20 from the heated lower chamber window 64 and susceptor 74. That is, in addition to the light radiated from the semiconductor wafer W, disturbance light from the lower chamber window 64 and susceptor 74 also enters the radiation thermometer 20, preventing the radiation thermometer 20 from measuring the temperature accurately. For this reason, in this embodiment, the influence of disturbance light is eliminated as follows.

[0083] A resistance change occurring in the light receiving element of the radiation thermometer 20 that receives the radiation containing the disturbance component is converted into a voltage signal by the signal conversion circuit 102 and output. The signal output from the signal conversion circuit 102 is treated as a detection signal output from the radiation thermometer 20. In this embodiment, a low-frequency signal is extracted from the detection signal output from the radiation thermometer 20 (step S32).

[0084] The detection signal output from the radiation thermometer 20 passes through either the first low-pass filter 111 or the second low-pass filter 112, which are connected in parallel. Both the first low-pass filter 111 and the second low-pass filter 112 are low-pass filters that pass frequency components lower than a predetermined cutoff frequency. However, the first low-pass filter 111 and the second low-pass filter 112 have different cutoff frequencies. The cutoff frequency (first cutoff frequency) of the first low-pass filter 111 is a value corresponding to the frequency characteristics of the lower chamber window 64, which is a quartz window, and is, for example, 1×10 -3 Hz. On the other hand, the cutoff frequency (second cutoff frequency) of the second low-pass filter 112 is a value corresponding to the frequency characteristics of the quartz susceptor 74, and is, for example, 2×10 -2 Hz. Each of first low-pass filter 111 and second low-pass filter 112 is expressed by a second-order transfer function, and has a pole on the negative real axis so that the filter itself converges without oscillating.

[0085] FIG. 13 is a Bode plot showing the frequency characteristics of the lower chamber window 64 and the susceptor 74. The figure also shows the frequency characteristics of the radiation thermometer 20. These frequency characteristics can be obtained from actual measurement data or a model created by CAE (Computer Aided Engineering). The change points in the frequency characteristics of the radiation thermometer 20 are close to the break points in the frequency characteristics of the lower chamber window 64 and the susceptor 74. This suggests that ambient light from the lower chamber window 64 and the susceptor 74 is affecting the measurements of the radiation thermometer 20.

[0086] Furthermore, the lower chamber window 64, which has a relatively large heat capacity compared to the susceptor 74, responds slower to heat input than the susceptor 74. That is, when the halogen lamps HL are turned on, the temperature rise rate of the lower chamber window 64 is slower than that of the susceptor 74, and conversely, when the halogen lamps HL are turned off, the temperature drop rate of the lower chamber window 64 is slower than that of the susceptor 74. For this reason, the susceptor 74 maintains a higher gain than the lower chamber window 64 even at higher frequencies.

[0087] In the first embodiment, the frequency characteristic of the lower chamber window 64 is such that the gain is reduced by about 3 dB (1×10 -3 Hz) is set as the first cutoff frequency of the first low-pass filter 111. In addition, the frequency at which the gain is reduced by about 3 dB in the frequency characteristics of the susceptor 74 (2×10 -2 Hz) is set as the second cutoff frequency of the second low-pass filter 112. Therefore, when the detection signal output from the radiation thermometer 20 passes through the first low-pass filter 111, disturbance components originating from the disturbance light from the lower chamber window 64 are extracted from the light incident on the radiation thermometer 20. Furthermore, when the detection signal output from the radiation thermometer 20 passes through the second low-pass filter 112, disturbance components originating from the disturbance light from the susceptor 74 are extracted from the light incident on the radiation thermometer 20.

[0088] The combining unit 105 combines the signal that has passed through the first low-pass filter 111 and the signal that has passed through the second low-pass filter 112. At this time, the combining unit 105 acquires a low-frequency signal by adding together components obtained by multiplying the signals output from the first low-pass filter 111 and the second low-pass filter 112 by a proportionality coefficient corresponding to the area ratio between the lower chamber window 64 and the susceptor 74 in the optical path incident on the radiation thermometer 20. For example, assume that the area ratio between the lower chamber window 64 and the susceptor 74 in the optical path incident on the radiation thermometer 20 (i.e., the field of view of the radiation thermometer 20) is 7:3. In this case, the combining unit 105 acquires a low-frequency signal by adding together the signal output from the first low-pass filter 111 multiplied by 0.7 and the signal output from the second low-pass filter 112 multiplied by 0.3.

[0089] The low-frequency signal extracted from the detection signal of the radiation thermometer 20 in this manner contains a component derived from the disturbance light incident on the radiation thermometer 20. However, the low-frequency signal contains not only a component derived from the disturbance light but also a component derived from the light incident on the radiation thermometer 20 from the semiconductor wafer W. For this reason, the correction unit 107 multiplies the low-frequency signal output from the synthesis unit 105 by a correction coefficient to obtain a disturbance signal derived only from the disturbance light incident on the radiation thermometer 20 (step S33).

[0090] In the first embodiment, the reflectance of the underside of the semiconductor wafer W is used as the correction coefficient by which the low-frequency signal is multiplied. Specifically, for example, before the semiconductor wafer W is loaded into the heat treatment apparatus 1, the reflectance of the underside of the semiconductor wafer W is measured using a reflectance measuring device separate from the heat treatment apparatus 1, and the measured reflectance is transferred to the heat treatment apparatus 1 and stored in the memory of the control unit 3. The correction unit 107 multiplies the low-frequency signal by the reflectance of the semiconductor wafer W as a correction coefficient to obtain the disturbance signal.

[0091] Next, the temperature calculation unit 108 calculates the temperature of the semiconductor wafer W, which is the object to be measured by the radiation thermometer 20, based on the detection signal of the radiation thermometer 20 and the disturbance signal output from the correction unit 107 (step S34). Specifically, the temperature calculation unit 108 acquires a signal obtained by subtracting a disturbance signal derived only from the disturbance light incident on the radiation thermometer 20 from a detection signal based on all light incident on the radiation thermometer 20. This signal is derived only from the light radiated from the semiconductor wafer W among the light incident on the radiation thermometer 20. The temperature calculation unit 108 then performs a predetermined arithmetic process on the signal obtained by subtracting the disturbance signal from the detection signal of the radiation thermometer 20, to calculate the temperature of the semiconductor wafer W. This arithmetic process itself is a well-known process for calculating the temperature of the object to be measured from the output signal of the radiation thermometer 20.

[0092] The temperature calculation unit 108 calculates the temperature of the semiconductor wafer W based on a signal derived from light obtained by eliminating the effects of ambient light from all light incident on the radiation thermometer 20 (i.e., a signal derived only from light emitted from the semiconductor wafer W). Therefore, the temperature calculation unit 108 can obtain an accurate temperature of the semiconductor wafer W, excluding the effects of ambient light.

[0093] Returning to Figure 9, the temperature of the semiconductor wafer W accurately measured by the radiation thermometer 20 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 raised by the light irradiation from the halogen lamps HL, has reached a predetermined preheating temperature T1. That is, the control unit 3 feedback-controls the output of the halogen lamps HL based on the measurement value by the radiation thermometer 20 so that the temperature of the semiconductor wafer W becomes the preheating temperature T1 (step S4). The radiation thermometer 20 serves as a control temperature sensor for controlling the output of the halogen lamps HL during preheating of the semiconductor wafer W.

[0094] 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 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.

[0095] By performing preheating using the halogen lamps HL in this manner, the temperature of the entire semiconductor wafer W is uniformly raised to the preheating temperature T1. During preheating using the halogen lamps HL, the temperature of the peripheral portion of the semiconductor wafer W, where heat dissipation is more likely, tends to be lower than that of the central portion, but the arrangement density of the halogen lamps HL in the halogen heating unit 4 is higher in the region facing the peripheral portion of the semiconductor wafer W than in the region facing the central portion. As a result, a greater amount of light is irradiated onto the peripheral portion of the semiconductor wafer W, where heat dissipation is more likely, and the in-plane temperature distribution of the semiconductor wafer W during the preheating stage can be made uniform.

[0096] 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 S5). At this time, part of the flash light emitted from the flash lamps FL heads directly into the chamber 6, and the other part is reflected by the reflector 52 before heading into the chamber 6, and the semiconductor wafer W is flash-heated by the irradiation of these flash lights.

[0097] The flash light emitted from the flash lamp FL is an extremely short, intense flash of light with an irradiation time of about 0.1 to 100 milliseconds, in which electrostatic energy previously stored in a capacitor is converted into an extremely short light pulse. When this extremely short, intense flash light is irradiated, the surface temperature of the semiconductor wafer W rises instantaneously to a processing temperature T2 of 1000°C or higher, and then rapidly drops.

[0098] After the flash heating process is completed, the halogen lamps HL are turned off after a predetermined time has elapsed. This causes the temperature of the semiconductor wafer W to rapidly decrease from the preheating temperature T1. The temperature of the semiconductor wafer W during this decrease is measured by the radiation thermometer 20, and the measurement result is transmitted to the control unit 3. The control unit 3 monitors, based on the measurement result from the radiation thermometer 20, whether the temperature of the semiconductor wafer W has decreased to a predetermined temperature. After the temperature of the semiconductor wafer W has decreased 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 upper surface of the susceptor 74 and receive the heat-treated 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).

[0099] In the first embodiment, the temperature of the semiconductor wafer W held on the susceptor 74 in the chamber 6 is measured by the radiation thermometer 20. Not only light emitted from the semiconductor wafer W, but also light emitted from structures within the chamber, such as the lower chamber window 64 and the susceptor 74, enters the radiation thermometer 20 as disturbance light. Such disturbance light can cause measurement errors in the radiation thermometer 20, so it is necessary to eliminate its influence as much as possible.

[0100] Typically, multiple semiconductor wafers W constituting a lot are loaded one by one into chamber 6 in sequence and heat-treated. Each time a new semiconductor wafer W is loaded into chamber 6, the halogen lamps HL are turned on to perform preheating, and then flash light is irradiated from the flash lamps FL. After flash heating of that semiconductor wafer W is completed, the halogen lamps HL are turned off. That is, in heat treatment apparatus 1, the flash lamps FL and halogen lamps HL are turned on in sequence repeatedly to irradiate light onto the multiple semiconductor wafers W constituting a lot. In particular, the repeated turning on and off of the halogen lamps HL causes a heat cycle in which the temperature repeatedly rises and falls in the chamber structures such as the lower chamber window 64 and the susceptor 74.

[0101] The heat capacity of the lower chamber window 64 and susceptor 74, which are made of quartz and have a considerable thickness, is significantly greater than the heat capacity of the thin silicon semiconductor wafer W. Therefore, when the halogen lamps HL are turned on or off, the thermal response of the lower chamber window 64 and susceptor 74 is significantly slower than the thermal response of the semiconductor wafer W. This means that the frequency components in the heat cycle of the lower chamber window 64 and susceptor 74 are lower in the low range than the frequency components of the semiconductor wafer W when irradiated with light.

[0102] The present invention separates and extracts disturbance components of the lower chamber window 64, the susceptor 74, etc. from the light incident on the radiation thermometer 20 based on the difference between the frequency components in the heat cycle of the lower chamber window 64 and the susceptor 74 and the frequency components of the semiconductor wafer W during light irradiation. That is, a low-frequency signal having a frequency lower than the thermal response of the semiconductor wafer W during light irradiation is extracted by the first low-pass filter 111 and the second low-pass filter 112 from the detection signal output from the radiation thermometer 20 that receives radiation light containing the disturbance components. A signal derived from the radiation light from the semiconductor wafer W, which has high frequency components, cannot pass through the first low-pass filter 111 and the second low-pass filter 112. On the other hand, a signal derived from the disturbance light from the lower chamber window 64 and the susceptor 74, which has low frequency components, is extracted as a low-frequency signal by the first low-pass filter 111 and the second low-pass filter 112. The first low-pass filter 111 extracts disturbance components that are mainly derived from disturbance light from the lower chamber window 64. On the other hand, the second low-pass filter 112 extracts disturbance components that are mainly derived from disturbance light from the susceptor 74. Furthermore, each of the first low-pass filter 111 and the second low-pass filter 112 is expressed by a second-order transfer function with a pole on the negative real axis, and therefore oscillation of the filter itself can be suppressed.

[0103] Furthermore, in the first embodiment, a low-frequency signal is acquired by adding together components obtained by multiplying the signals output from the first low-pass filter 111 and the second low-pass filter 112 by a proportionality coefficient according to the area ratio between the lower chamber window 64 and the susceptor 74 in the light path incident on the radiation thermometer 20. This makes it possible to more accurately extract signals derived from ambient light from the lower chamber window 64 and the susceptor 74 as low-frequency signals.

[0104] However, the extracted low-frequency signal inevitably contains not only disturbance components originating from the disturbance light from the lower chamber window 64 and the susceptor 74, but also components originating from the radiation light from the semiconductor wafer W. Therefore, the extracted low-frequency signal is corrected by multiplying it by a correction coefficient to obtain a disturbance signal containing only the components originating from the disturbance light incident on the radiation thermometer 20.

[0105] Finally, the temperature of the semiconductor wafer W is calculated based on a signal obtained by subtracting the disturbance signal from the detection signal of the radiation thermometer 20. The disturbance signal is a signal derived solely from the disturbance light, and the signal derived solely from the detection signal of the radiation thermometer 20 by subtracting the disturbance signal is a signal derived solely from the light emitted from the semiconductor wafer W. Therefore, by calculating the temperature based on this signal, the exact temperature of the semiconductor wafer W can be determined with high precision. That is, by performing the first embodiment as described above, the disturbance light component can be accurately separated from all light incident on the radiation thermometer 20, and the temperature of the semiconductor wafer W can be measured with high precision. Furthermore, if the disturbance light component can be accurately separated, the number and time of dummy wafer processing performed in the dummy processing performed to stabilize the disturbance component can be reduced, leading to an increase in the operating rate of the heat treatment apparatus 1.

[0106] Second Embodiment Next, a second embodiment of the present invention will be described. In the first embodiment, the reflectance of the semiconductor wafer W as the correction coefficient used in step S33 is measured in advance before the semiconductor wafer W is carried into the heat treatment apparatus 1. In the second embodiment, the reflectance of the semiconductor wafer W is measured sequentially inside the chamber 6.

[0107] FIG. 14 is a diagram showing a schematic configuration of a heat treatment apparatus 1a according to the second embodiment. In this figure, the same elements as those in the first embodiment are denoted by the same reference numerals. In the second embodiment, a reflectance measuring device 210 is provided in the chamber 6 of the heat treatment apparatus 1a. The reflectance measuring device 210 includes a light projector 211 and a light receiver 212 located below the susceptor 74. Light emitted from the light projector 211 is reflected by the underside of the semiconductor wafer W, and the light receiver 212 receives the reflected light. The reflectance measuring device 210 measures the reflectance of the semiconductor wafer W based on the intensity of the light emitted from the light projector 211 and the intensity of the light received by the light receiver 212. Note that the reflectance measured by the reflectance measuring device 210 may be the relative reflectance with respect to that of a bare silicon wafer. Other than the reflectance measuring device 210, the remaining configuration of the heat treatment apparatus 1a is the same as that of the first embodiment.

[0108] In the second embodiment, the reflectance of the underside of the semiconductor wafer W is measured sequentially even during light irradiation from the halogen lamps HL and the flash lamps FL. Then, in the correction process of step S33 (FIG. 10), the correction unit 107 multiplies the low-frequency signal by the reflectance of the semiconductor wafer W measured sequentially by the reflectance measuring device 210 during light irradiation as a correction coefficient to obtain a disturbance signal. Note that the remaining processing operations in the heat treatment apparatus 1 are the same as those in the first embodiment, except for the fact that the reflectance of the semiconductor wafer W is measured sequentially.

[0109] The reflectance of the semiconductor wafer W may fluctuate when the temperature of the semiconductor wafer W rises due to light irradiation. In the second embodiment, the reflectance of the semiconductor wafer W that fluctuates during light irradiation can be measured sequentially and reflected in the correction coefficient. This makes it possible to more accurately separate disturbance light components from all light incident on the radiation thermometer 20 and measure the temperature of the semiconductor wafer W with high accuracy.

[0110] Third Embodiment Next, a third embodiment of the present invention will be described. The configuration of the heat treatment apparatus of the third embodiment is the same as the heat treatment apparatus 1 of the first embodiment. Furthermore, the processing operation of the heat treatment apparatus of the third embodiment is also generally the same as that of the first embodiment. In the first and second embodiments, the reflectance of the semiconductor wafer W was used as the correction coefficient used in step S33, but in the third embodiment, the correction coefficient is determined using a semiconductor wafer with a thermocouple attached (hereinafter referred to as a "TC wafer").

[0111] In the third embodiment, the correction coefficient is determined using a TC wafer, for example, during maintenance of the heat treatment apparatus 1. The TC wafer is a silicon disk-shaped substrate similar to a normal semiconductor wafer W, except that a thermocouple is attached to the TC wafer.

[0112] Since a TC wafer equipped with a thermocouple cannot be transported by a transport robot, during maintenance it is manually carried into the chamber 6 and placed on the susceptor 74. With the TC wafer held on the susceptor 74, the halogen lamps HL are turned on to heat the TC wafer.

[0113] The temperature of the TC wafer, which rises due to the light irradiation from the halogen lamp HL, is measured by the thermocouple and also by the radiation thermometer 20. Temperature measurement by the thermocouple is not affected by ambient light. Furthermore, the thermocouple can accurately measure temperature regardless of the emissivity of the object being measured. In other words, the temperature measured by the thermocouple is the true temperature of the TC wafer being heated.

[0114] Meanwhile, the radiation thermometer 20 measures the temperature of the TC wafer according to the same procedure (FIG. 10) as in the first embodiment. That is, a low-frequency signal is extracted from the detection signal output from the radiation thermometer 20 using a low-pass filter, and the low-frequency signal is multiplied by a correction coefficient to obtain a disturbance signal. For example, a provisionally determined value may be used as the correction coefficient. Then, the temperature of the TC wafer is calculated based on the signal obtained by subtracting the disturbance signal from the detection signal of the radiation thermometer 20.

[0115] The temperature measurement value of the radiation thermometer 20 is the result of calculation using a provisionally determined correction coefficient. The difference between the temperature measurement value by the thermocouple and the temperature measurement value by the radiation thermometer 20 is presumed to be due to the correction coefficient. Therefore, in the third embodiment, the correction coefficient is determined so that the measurement value of the temperature of the TC wafer measured by the thermocouple matches the measurement value of the temperature of the TC wafer measured by the radiation thermometer 20. In other words, the correction coefficient is calibrated using the thermocouple.

[0116] According to the third embodiment, it is possible to derive an accurate correction coefficient based on the true temperature measurement value obtained by the thermocouple, and as a result, it is possible to more accurately separate the disturbance light component from all the light incident on the radiation thermometer 20, thereby enabling the temperature of the semiconductor wafer W to be measured with high precision.

[0117] <Fourth embodiment> Next, a fourth embodiment of the present invention will be described. The configuration of the heat treatment apparatus of the fourth embodiment is the same as that of the heat treatment apparatus 1 of the first embodiment. Furthermore, the processing operation of the heat treatment apparatus of the fourth embodiment is also generally the same as that of the first embodiment. While the first and second embodiments employ the reflectance of the semiconductor wafer W as the correction coefficient used in step S33, in the fourth embodiment, the correction coefficient is determined using a dynamic characteristic model that mathematically represents the temperature change of the semiconductor wafer W over time.

[0118] In the fourth embodiment, a dynamic characteristics model is constructed in advance, which mathematically represents the temporal temperature changes of the semiconductor wafer W and the chamber internal structures (such as the lower chamber window 64 and susceptor 74) that affect the temperature measurement value of the radiation thermometer 20. An extended Kalman filter is then constructed from this dynamic characteristics model. The extended Kalman filter is also applicable to nonlinear dynamic characteristics models. The extended Kalman filter of the fourth embodiment can sequentially estimate the temperatures of the semiconductor wafer W and the chamber internal structures based on the dynamic characteristics model.

[0119] In the fourth embodiment, for example, during maintenance of the heat treatment apparatus 1, the halogen lamps HL are turned on to heat the semiconductor wafer W while the semiconductor wafer W is held on the susceptor 74. The radiation thermometer 20 measures the temperature of the semiconductor wafer W as it is heated according to the same procedure (FIG. 10) as in the first embodiment. Then, a correction coefficient is determined so that the measured value of the temperature of the semiconductor wafer W measured by the radiation thermometer 20 matches the temperature of the semiconductor wafer W estimated from the dynamic characteristics model described above. In other words, the correction coefficient is calibrated using the model.

[0120] According to the fourth embodiment, an accurate correction coefficient can be derived based on the temperature estimated from the dynamic characteristics model, and as a result, the ambient light component can be more accurately separated from all the light incident on the radiation thermometer 20, thereby enabling the temperature of the semiconductor wafer W to be measured with high precision.

[0121] <Modification> Although the embodiments of the present invention have been described above, various modifications other than those described above are possible without departing from the spirit and scope of the present invention. For example, in the first embodiment, low-frequency signals are extracted from the detection signal of the radiation thermometer 20 using two low-pass filters, the first low-pass filter 111 corresponding to the lower chamber window 64 and the second low-pass filter 112 corresponding to the susceptor 74. However, this is not limited to this. In addition to the first low-pass filter 111 and the second low-pass filter 112, a low-pass filter having a cutoff frequency corresponding to the frequency characteristics of the upper chamber window 63 may be provided. Furthermore, a low-pass filter having a cutoff frequency corresponding to the frequency characteristics of the chamber side portion 61 of the chamber 6 may be provided. In other words, low-frequency signals may be extracted from the detection signal of the radiation thermometer 20 using three or more low-pass filters having different cutoff frequencies.

[0122] Furthermore, in the first and second embodiments, the reflectance of the semiconductor wafer W is used as the correction coefficient used in step S33, but the emissivity or transmittance of the semiconductor wafer W may also be used as the correction coefficient. Alternatively, a combination of the reflectance, emissivity, and transmittance of the semiconductor wafer W may also be used as the correction coefficient. The sum of the reflectance, emissivity, and transmittance is 1.

[0123] Alternatively, the reflectance may be measured as a correction coefficient as follows: The heat treatment apparatus 1 is provided with a radiation thermometer for measuring the temperature of the susceptor 74 during heat treatment of the semiconductor wafer W. When the semiconductor wafer W is loaded into the chamber 6, the difference between the measurement value of the radiation thermometer 20 when the semiconductor wafer W is supported by the lift pins 12 (when the semiconductor wafer W is spaced apart from the susceptor 74) and the measurement value of the radiation thermometer 20 when the semiconductor wafer W is placed on the susceptor 74 is calculated. Then, the reflectance of the semiconductor wafer W is calculated based on this difference and the measured temperature value of the susceptor 74.

[0124] Furthermore, in each of the above embodiments, a low-frequency signal having a frequency lower than the thermal response of the semiconductor wafer W when irradiated with light is extracted using a low-pass filter, but conversely, disturbance components may be separated and removed using a band-pass filter or high-pass filter that extracts only a frequency region corresponding to the thermal response of the semiconductor wafer W. Since disturbance components have been removed from the signal extracted from the detection signal of the radiation thermometer 20 using a band-pass filter or high-pass filter, the temperature of the semiconductor wafer W can be calculated directly.

[0125] Furthermore, in the above embodiment, the flash heating unit 5 is provided 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 provided in the halogen heating unit 4 is not limited to 40 and can be any number.

[0126] Furthermore, in the above embodiment, the preheating process of the semiconductor wafer W is performed using a filament-type halogen lamp HL as a continuously lit lamp that emits light continuously for one second or more, but this is not limited to this, and the preheating process may also be performed using a discharge-type arc lamp (e.g., a xenon arc lamp) or an LED lamp as a continuously lit lamp instead of the halogen lamp HL. [Explanation of symbols]

[0127] 1. Heat treatment equipment 3. Control Unit 4 Halogen heating section 5 Flash heating section 6 chambers 7 Holding part 10 Transfer mechanism 20 Radiation thermometer 61 Chamber side 65 Heat Treatment Space 74 Susceptor 75 Retaining Plate 105 Synthesis Section 107 Correction Unit 108 Temperature calculation section 111 1st low-pass filter 112 Second low-pass filter 210 Reflectance measuring instrument 211 Floodlight 212 Receiver FL flash lamp HL halogen lamp W Semiconductor wafer

Claims

1. A temperature measurement method for measuring the temperature of a substrate heated by light irradiation, comprising: a light receiving step of receiving, with a radiation thermometer, radiation emitted from the substrate carried into the chamber; an extraction step of extracting a low-frequency signal having a frequency lower than the thermal response of the substrate when irradiated with light from the detection signal output from the radiation thermometer using a low-pass filter that passes signals with a frequency lower than a predetermined cutoff frequency; a correction step of multiplying the low-frequency signal by a correction coefficient to obtain a disturbance signal derived from disturbance light incident on the radiation thermometer; a temperature calculation step of calculating a temperature of the substrate based on a signal obtained by subtracting the disturbance signal from the detection signal; A temperature measurement method comprising:

2. 2. The temperature measurement method according to claim 1, In the extracting step, the low-frequency signal is extracted from the detection signal using a plurality of low-pass filters having different cutoff frequencies.

3. 3. The temperature measurement method according to claim 2, The temperature measurement method, wherein the plurality of low-pass filters include a first low-pass filter having a first cutoff frequency corresponding to a quartz window provided in the chamber and a second low-pass filter having a second cutoff frequency corresponding to a quartz susceptor that holds the substrate in the chamber.

4. 4. The temperature measurement method according to claim 3, In the extraction step, the low-frequency signal is acquired by summing components obtained by multiplying the outputs of the first low-pass filter and the second low-pass filter by a proportionality coefficient corresponding to the area ratio between the quartz window and the susceptor in the optical path incident on the radiation thermometer.

5. 2. The temperature measurement method according to claim 1, A temperature measurement method in which the low-pass filter is expressed by a second-order transfer function having a pole on the negative real axis.

6. 2. The temperature measurement method according to claim 1, The temperature measurement method, wherein the correction coefficient is the reflectance of the substrate.

7. 7. The temperature measurement method according to claim 6, A temperature measurement method for sequentially measuring the reflectance of the substrate during light irradiation.

8. 2. The temperature measurement method according to claim 1, A temperature measurement method for deriving the correction coefficient so that when a thermocouple-equipped substrate having a thermocouple attached thereto is irradiated with light to raise its temperature, a measured value obtained by measuring the temperature of the thermocouple-equipped substrate using the thermocouple coincides with a measured value obtained by measuring the temperature of the thermocouple-equipped substrate using the radiation thermometer.

9. 2. The temperature measurement method according to claim 1, a temperature measurement method in which the substrate is irradiated with light to raise the temperature, and the temperature of the substrate is measured using the radiation thermometer, and the correction coefficient is derived so that the measured value coincides with the temperature of the substrate estimated from a dynamic characteristics model that mathematically expresses the temperature change of the substrate.

10. The temperature measurement method according to any one of claims 1 to 9, A temperature measurement method in which a flash lamp and a continuous lighting lamp are turned on repeatedly in sequence to irradiate multiple substrates with light.

11. A heat treatment apparatus that heats a substrate by irradiating the substrate with light, a chamber for housing the substrate; a quartz susceptor that holds the substrate within the chamber; a light irradiation unit provided outside the chamber and configured to irradiate the substrate held by the susceptor with light; a radiation thermometer for measuring the temperature of the substrate held by the susceptor; a low-pass filter that passes signals with frequencies lower than a predetermined cutoff frequency from the detection signal output from the radiation thermometer that receives the radiation light emitted from the substrate, and extracts low-frequency signals with frequencies lower than the thermal response of the substrate when irradiated with light; a correction unit that multiplies the low-frequency signal by a correction coefficient to obtain a disturbance signal derived from disturbance light incident on the radiation thermometer; a temperature calculation unit that calculates the temperature of the substrate based on a signal obtained by subtracting the disturbance signal from the detection signal; A heat treatment device comprising:

12. 12. The heat treatment apparatus according to claim 11, The heat treatment device extracts the low frequency signal from the detection signal using a plurality of low pass filters having different cutoff frequencies.

13. 13. The heat treatment apparatus according to claim 12, The plurality of low-pass filters include a first low-pass filter having a first cutoff frequency corresponding to a quartz window provided in the chamber and a second low-pass filter having a second cutoff frequency corresponding to the susceptor.

14. 14. The heat treatment apparatus according to claim 13, a heat treatment apparatus that acquires the low-frequency signal by summing components obtained by multiplying the outputs of the first low-pass filter and the second low-pass filter by a proportionality coefficient that corresponds to an area ratio between the quartz window and the susceptor in an optical path incident on the radiation thermometer.

15. 12. The heat treatment apparatus according to claim 11, The heat treatment device, wherein the low-pass filter is expressed by a second-order transfer function having a pole on the negative real axis.

16. 12. The heat treatment apparatus according to claim 11, The heat treatment apparatus, wherein the correction coefficient is the reflectance of the substrate.

17. 17. The heat treatment apparatus according to claim 16, A heat treatment apparatus that sequentially measures the reflectance of the substrate when irradiated with light from the light irradiating unit.

18. 18. The heat treatment apparatus according to claim 11, the light irradiation unit includes a flash lamp and a continuous lighting lamp, A heat treatment apparatus in which the flash lamps and the continuous lighting lamps are turned on repeatedly in sequence to irradiate a plurality of substrates with light.

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