Temperature measurement method

Abstract

To provide a temperature measurement method capable of measuring temperature of a board with high precision by accurately calculating strength of disturbance light impinging on a radiation thermometer.SOLUTION: Before carrying a semiconductor wafer into a chamber, measurement is performed by an edge radiation thermometer. After carrying in a semiconductor wafer, measurement is performed by the edge radiation thermometer in a state in which the semiconductor wafer is supported by a lift pin and in a state in which it is placed on a susceptor. Reflectance of the semiconductor wafer is calculated from the measurement values, and strength of turbulence light impinging on the edge radiation thermometer is calculated based on the reflectance, and strength of radiation light radiated from a quartz window. Temperature of the semiconductor wafer is calculated by subtracting the strength of turbulence light from the strength of light received by the edge radiation thermometer during a heating process of the semiconductor wafer.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a temperature measurement method for measuring the temperature of a substrate heated by light irradiation. Substrates to be processed include, for example, semiconductor wafers, substrates for liquid crystal displays, substrates for flat panel displays (FPDs), substrates for optical disks, substrates for magnetic disks, and substrates for solar cells. [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 temperature of the quartz window and other components constantly fluctuates 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. Therefore, the intensity of the ambient light emitted from the quartz window and reflected by the front or back surface of the semiconductor wafer also fluctuates constantly, and temperature measurement that takes such fluctuations in ambient light into account is required.

[0008] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a temperature measurement method that can accurately calculate the intensity 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 problem, the invention of claim 1 is a temperature measurement method for measuring the temperature of a substrate heated by light irradiation, comprising: a reflectance measurement step for measuring the reflectance of a substrate carried into a chamber; a disturbance light calculation step for calculating the intensity of disturbance light incident on a radiation thermometer that measures the temperature of the substrate based on the reflectance measured in the reflectance measurement step and the intensity of radiation light emitted from a quartz window provided in the chamber; and a substrate temperature calculation step for calculating the temperature of the substrate by subtracting the intensity of the disturbance light from the intensity of light received by the radiation thermometer when the substrate is heated by light irradiation.

[0010] Furthermore, the invention of claim 2 is characterized in that in the temperature measurement method according to the invention of claim 1, the disturbance light calculation step calculates the intensity of the disturbance light based on the intensity of the radiated light from the quartz window, which changes sequentially when the substrate is heated by light irradiation.

[0011] The invention of claim 3 is characterized in that in the temperature measurement method according to the invention of claim 1 or claim 2, the intensity of the light emitted from the quartz window is determined by measurement using a measuring device.

[0012] Furthermore, the invention of claim 4 is characterized in that in the temperature measurement method according to the invention of claim 1 or claim 2, the intensity of the radiation from the quartz window is determined from a mathematical model.

[0013] The invention of claim 5 is characterized in that, in the temperature measurement method of the invention of claim 1, in the reflectance measurement step, the reflectance is calculated based on the intensity of light received by the radiation thermometer when the substrate carried into the chamber is supported at a distance from a susceptor, the intensity of light received by the radiation thermometer when the substrate is placed on the susceptor, and the intensity of light emitted from the susceptor. [Effects of the Invention]

[0014] According to the inventions of claims 1 to 5, the reflectance of the substrate is measured, and the intensity of the ambient light incident on the radiation thermometer is calculated based on that reflectance and the intensity of the radiation light emitted from the quartz window. The temperature of the substrate is calculated by subtracting the intensity of the ambient light from the intensity of the light received by the radiation thermometer when the substrate is heated by light irradiation, so that the intensity of the ambient light incident on the radiation thermometer can be accurately calculated and the temperature of the substrate can be measured with high precision.

[0015] In particular, according to the invention of claim 2, the intensity of the ambient light is calculated based on the intensity of the light emitted from the quartz window, which changes gradually when the substrate is heated by light irradiation, so that the intensity of the ambient light, which changes gradually, can be calculated more appropriately and the temperature of the substrate can be measured more accurately. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a vertical cross-sectional view showing the configuration of a heat treatment apparatus for carrying out a temperature measuring method according to the present invention. [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] 10 is a flowchart showing a procedure of a processing operation in a heat treatment apparatus. [Figure 9] FIG. 10 is a diagram showing a schematic view of measurements by an edge radiation thermometer when no semiconductor wafer is present in the chamber. [Figure 10] FIG. 10 is a diagram illustrating measurements by an edge pyrometer when a semiconductor wafer is supported on lift pins. [Figure 11] FIG. 1 is a diagram illustrating a measurement using an edge radiation thermometer when a semiconductor wafer is placed on a susceptor. [Figure 12] FIG. 10 is a vertical cross-sectional view showing the configuration of a heat treatment apparatus according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] 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."

[0018] First Embodiment FIG. 1 is a longitudinal cross-sectional view showing the configuration of a heat treatment apparatus 1 for carrying out a temperature measurement method 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 (φ300 mm in this embodiment). 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] Furthermore, the chamber side portion 61 is provided with a through-hole 61a and a through-hole 61b. An edge radiation thermometer (edge ​​pyrometer) 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 radiated from the underside of a semiconductor wafer W held on a susceptor 74 (described later) to the edge radiation thermometer 20. Meanwhile, a center radiation thermometer (center pyrometer) 25 is attached to the portion of the outer wall surface of the chamber side portion 61 where the through-hole 61b is provided. The through-hole 61b is a cylindrical hole for guiding infrared light radiated from the susceptor 74 to the center radiation thermometer 25. The through-holes 61a and 61b are provided at an angle relative to the horizontal direction so that their axes in the penetration direction intersect with the main surface of the semiconductor wafer W held on the susceptor 74. Therefore, the edge radiation thermometer 20 and the central radiation thermometer 25 are provided diagonally below the susceptor 74. Transparent windows 21 and 26 made of barium fluoride material that transmit infrared light in the wavelength range that can be measured by the edge radiation thermometer 20 and the central radiation thermometer 25 are attached to the ends of the through holes 61a and 61b that face the heat treatment space 65, respectively.

[0025] 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.

[0026] 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.

[0027] A gas exhaust pipe 191 for discharging gas from the heat treatment space 65 is also connected to the tip of the transfer opening 66. The gas exhaust pipe 191 is connected to an exhaust unit 190 via a valve 192. By opening the valve 192, the gas in the chamber 6 is exhausted through the transfer opening 66.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 2 and 3, an opening 78 is formed in the holding plate 75 of the susceptor 74, penetrating vertically. The opening 78 is provided so that the edge radiation thermometer 20 can receive radiation (infrared light) emitted from the underside of the semiconductor wafer W. That is, the edge 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 61a, thereby measuring the temperature of the semiconductor wafer W. Furthermore, the holding plate 75 of the susceptor 74 is formed with four through-holes 79 through which lift pins 12 of the transfer mechanism 10, which will be described later, pass to transfer the semiconductor wafer W.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] The multiple 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.

[0041] A xenon flash lamp FL comprises a rod-shaped glass tube (discharge tube) filled with xenon gas and equipped 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 through 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, the insulation is broken down, and the electricity stored in the capacitor flows instantaneously through the glass tube, exciting the xenon atoms or molecules and emitting light. Such a xenon flash lamp FL converts electrostatic energy previously stored in the capacitor into extremely short light pulses of 0.1 to 100 milliseconds, thereby enabling it to emit much stronger light than continuous light sources such as halogen lamps HL. In other words, the flash lamp FL is a pulsed lamp that emits light instantaneously for an extremely short period of time, less than one second. The light-emitting duration 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] As shown in FIG. 1 , the chamber 6 is provided with two radiation thermometers: an edge radiation thermometer 20 and a center radiation thermometer 25. Both the edge radiation thermometer 20 and the center radiation thermometer 25 are provided below the semiconductor wafer W held on the susceptor 74. The edge radiation thermometer 20 receives infrared light radiated from the underside of the semiconductor wafer W through an opening 78, which is a notch provided in the susceptor 74, to measure the temperature of the underside. In other words, the measurement area of ​​the edge radiation thermometer 20 is inside the opening 78. On the other hand, the measurement area of ​​the center radiation thermometer 25 is within the plane of the holding plate 75 of the susceptor 74. The center radiation thermometer 25 receives infrared light radiated from the susceptor 74 to measure the temperature of the susceptor 74.

[0050] The control unit 3 controls the various operating mechanisms provided in the heat treatment apparatus 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) that stores control software, data, and the like. The CPU of the control unit 3 executes a predetermined processing program, thereby causing the processing in the heat treatment apparatus 1 to proceed. The control unit 3 also performs various arithmetic processing based on the measurements of the edge radiation thermometer 20 and the center radiation thermometer 25.

[0051] 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.

[0052] Next, a description will be given of the processing operation in the heat treatment apparatus 1 having the above configuration. Fig. 8 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.

[0053] In the heat treatment apparatus 1, multiple semiconductor wafers W constituting a lot are loaded one by one into the chamber 6 and heat-treated. When the multiple semiconductor wafers W are being heat-treated sequentially, the semiconductor wafers W absorb light irradiated from the halogen lamps HL and flash lamps FL and the heated semiconductor wafers W also heat up the chamber interior structures, such as the upper chamber window 63, the lower chamber window 64, and the susceptor 74, due to heat conduction and heat convection. For example, when multiple semiconductor wafers W are being steadily processed, the temperatures of the upper chamber window 63 and the lower chamber window 64 rise to approximately 20°C to 500°C. Therefore, radiant light emitted from these heated chamber interior structures is incident on the edge radiation thermometer 20 and the center radiation thermometer 25. As a result, the edge radiation thermometer 20 and the center radiation thermometer 25 continuously output measured values.

[0054] In this embodiment, measurement is performed by the edge radiation thermometer 20 immediately before the semiconductor wafer W to be processed is loaded into the chamber 6 (step S1). FIG. 9 is a diagram schematically illustrating measurement by the edge radiation thermometer 20 when no semiconductor wafer W is present in the chamber 6. Before the semiconductor wafer W is loaded into the chamber 6, i.e., when no semiconductor wafer W is present in the chamber 6, radiation emitted from the upper chamber window 63 passes through the opening 78 of the susceptor 74 and enters the edge radiation thermometer 20. However, because the measurement region of the edge radiation thermometer 20 is inside the opening 78, radiation emitted from the susceptor 74 does not enter the edge radiation thermometer 20. Furthermore, radiation emitted from the lower chamber window 64 does not enter the edge radiation thermometer 20. Therefore, when no semiconductor wafer W is present in the chamber 6, substantially only radiation from the upper chamber window 63 enters the edge radiation thermometer 20. Therefore, the measurement value Ip1 output from the edge radiation thermometer 20 immediately before the semiconductor wafer W is loaded into the chamber 6 is expressed by the following equation (1).

[0055]

number

[0056] In equation (1), Iuw is the intensity of the radiation light emitted from the upper chamber window 63. The edge radiation thermometer 20 and the center radiation thermometer 25 are sensors that measure the temperature of the object to be measured, but strictly speaking, the measurement values ​​that they directly output are values ​​that indicate the intensity of the light incident on the radiation thermometer, and the control unit 3, for example, performs temperature conversion processing on these values ​​to determine the temperature of the object to be measured.

[0057] After measurement using the edge radiation thermometer 20, the semiconductor wafer W to be processed is loaded into the chamber 6 (step S2). Prior to loading the wafer, the air supply valve 84 is opened, and the exhaust valves 89, 192 are also opened to start supplying and exhausting air to and from the chamber 6. When the valve 84 is opened, nitrogen gas is supplied to the heat treatment space 65 through the gas supply hole 81. When the valve 89 is opened, the gas in 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 in the chamber 6 flows downward and is exhausted from the lower part of the heat treatment space 65.

[0058] Furthermore, by opening the valve 192, the gas inside the chamber 6 is also exhausted from the transfer opening 66. Furthermore, the atmosphere around the drive unit of the transfer mechanism 10 is also exhausted by an exhaust mechanism (not shown). Note that during the heat treatment of the semiconductor wafer W in the heat treatment apparatus 1, nitrogen gas is continuously supplied to the heat treatment space 65, and the supply amount is changed as appropriate depending on the treatment process.

[0059] Next, gate valve 185 is opened to open transfer opening 66, and a semiconductor wafer W to be processed is carried into heat treatment space 65 in chamber 6 through transfer opening 66 by a transfer robot outside the apparatus. At this time, there is a risk that the atmosphere outside the apparatus may be drawn in as the semiconductor wafer W is carried in, 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 drawing in of such external atmosphere.

[0060] 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. After the semiconductor wafer W is supported by the lift pins 12, the transfer robot retreats from the heat treatment space 65, and the transfer opening 66 is closed by the gate valve 185.

[0061] Next, measurement is performed by the edge radiation thermometer 20 while the semiconductor wafer W is supported on the lift pins 12 (step S3). Fig. 10 is a diagram schematically showing measurement by the edge radiation thermometer 20 when the semiconductor wafer W is supported on the lift pins 12. When the semiconductor wafer W is supported on the lift pins 12, the semiconductor wafer W is held at an upper position spaced above the susceptor 74. Therefore, a relatively large gap exists between the semiconductor wafer W and the susceptor 74.

[0062] When the semiconductor wafer W is supported by the lift pins 12 at a distance from the susceptor 74, the following light is incident on the edge radiation thermometer 20: transmitted light emitted from the upper chamber window 63 and transmitted through the semiconductor wafer W; emitted light directly from the semiconductor wafer W; and reflected light emitted from the susceptor 74 and reflected by the back surface of the semiconductor wafer W. All of these light rays pass through the opening 78 of the susceptor 74 and enter the edge radiation thermometer 20. The measured value Ip2 output from the edge radiation thermometer 20 when the semiconductor wafer W is supported on the lift pins 12 is expressed by the following equation (2):

[0063]

number

[0064] In equation (2), tw and rw are the transmittance and reflectance of the semiconductor wafer W, respectively. Furthermore, Is is the intensity of the radiant light emitted from the susceptor 74. Furthermore, Iw is the intensity of the radiant light emitted from the semiconductor wafer W. Because the temperature of the semiconductor wafer W when it is loaded into the chamber 6 is approximately room temperature, the intensity Iw of the radiant light emitted from the semiconductor wafer W can be set to 0. Therefore, the following equation (3) is established from equations (1) and (2).

[0065]

number

[0066] Next, the pair of transfer arms 11 of the transfer mechanism 10 descend and the lift pins 12 exit downward through the through holes 79, whereby the semiconductor wafer W is transferred from the transfer mechanism 10 to the susceptor 74 and held from below in a horizontal position. The semiconductor wafer W is supported by a plurality of substrate support pins 77 erected on a holding plate 75 and held on the susceptor 74. The semiconductor wafer W is placed on the susceptor 74 with the front surface to be processed facing upward. The pair of transfer arms 11, which have descended below the susceptor 74, are retracted to a retracted position, i.e., inside the recess 62, by the horizontal movement mechanism 13. Then, with the semiconductor wafer W placed on the susceptor 74, measurement is again performed using the edge radiation thermometer 20 (step S4).

[0067] 11 is a diagram schematically showing measurement by the edge radiation thermometer 20 when the semiconductor wafer W is placed on the susceptor 74. When the semiconductor wafer W is placed on the susceptor 74, the semiconductor wafer W is held at a lower position close to the susceptor 74. There is only a small gap corresponding to the height of the substrate support pins 77 between the semiconductor wafer W and the holding surface 75a of the susceptor 74.

[0068] When a semiconductor wafer W is placed on the susceptor 74, the following light is incident on the edge radiation thermometer 20: transmitted light emitted from the upper chamber window 63 and transmitted through the semiconductor wafer W; emitted light directly from the semiconductor wafer W; and reflected light emitted from the lower chamber window 64 and reflected by the back surface of the semiconductor wafer W. When the semiconductor wafer W is placed on the susceptor 74, there is almost no gap between the semiconductor wafer W and the susceptor 74, and therefore no reflected light is emitted from the susceptor 74, reflected by the back surface of the semiconductor wafer W, passes through the opening 78, and enters the edge radiation thermometer 20. On the other hand, reflected light is generated that is emitted from the lower chamber window 64, passes through the opening 78, is reflected by the back surface of the semiconductor wafer W, passes through the opening 78 again, and enters the edge radiation thermometer 20. The measured value Ip3 output from the edge radiation thermometer 20 when the semiconductor wafer W is placed on the susceptor 74 is expressed by the following equation (4): The measured value Ip3 is the intensity of light received by the edge radiation thermometer 20 when the semiconductor wafer W is placed on the susceptor 74.

[0069]

number

[0070] In equation (4), Ilw is the intensity of the radiant light emitted from the lower chamber window 64. As described above, the temperature of the semiconductor wafer W immediately after it is placed on the susceptor 74 is approximately room temperature, so the intensity Iw of the radiant light emitted from the semiconductor wafer W can be set to 0. Therefore, the following equation (5) is established from equations (1) and (4).

[0071]

number

[0072] By subtracting equation (3) from equation (5), equation (6) is obtained. Then, equation (7) can be derived from equation (6).

[0073]

number

[0074]

number

[0075] In equation (7), the measured values ​​Ip2 and Ip3 are the actual measurements of the edge radiation thermometer 20 when the semiconductor wafer W is supported on the lift pins 12 and when the semiconductor wafer W is placed on the susceptor 74, respectively. The radiation emitted from the susceptor 74 is directly incident on the center radiation thermometer 25 (see FIG. 10). That is, the intensity Is of the radiation light emitted from the susceptor 74 is the actual measurement value of the center radiation thermometer 25. Therefore, if the intensity Ilw of the radiation light emitted from the lower chamber window 64 can be determined, the reflectance of the backside of the semiconductor wafer W in the chamber 6 can be calculated from equation (7).

[0076] The intensity Ilw of the radiant light emitted from the lower chamber window 64 is expressed as a function of the temperature of the lower chamber window 64. The lower chamber window 64 heats up by absorbing a portion of the light emitted from the halogen lamps HL, and the temperature of the lower chamber window 64 depends primarily on the lamp power of the halogen lamps HL. Therefore, in the first embodiment, prior to processing the semiconductor wafer W, a mathematical model such as a transfer function expressing the relationship between the lamp power of the multiple halogen lamps HL and the intensity Ilw of the radiant light emitted from the lower chamber window 64 is derived in advance. Specifically, for example, a contact thermometer such as a thermocouple is temporarily attached to the lower chamber window 64, the halogen lamps HL are turned on, and the temperature of the lower chamber window 64 is measured while changing the lamp power, thereby identifying the relationship between the time-varying lamp power and the measured temperature. A mathematical model such as a transfer function is then created by combining this with a function of the intensity Ilw of the radiant light emitted from the lower chamber window 64 and the temperature of the lower chamber window 64.

[0077] The control unit 3 provides the intensity of radiant light emitted from the lower chamber window 64 at room temperature as an initial value (Ilw0) to the mathematical model, and estimates the intensity Ilw of radiant light emitted from the lower chamber window 64, which changes sequentially, by inputting the lamp power of the halogen lamp HL, which changes over time. The control unit 3 then obtains the intensity Ilw of radiant light emitted from the lower chamber window 64 at the time the semiconductor wafer W is carried into the chamber 6 from the mathematical model, and calculates the reflectance of the semiconductor wafer W from equation (7) using this value and the actual measured values ​​from the edge radiation thermometer 20 and the center radiation thermometer 25 (step S5).

[0078] Next, the heating process of the semiconductor wafer W is started (step S6). Specifically, the 40 halogen lamps HL of the halogen heating unit 4 are turned on all at once to start preheating (assisted heating) of the semiconductor wafer W. The halogen light emitted from the halogen lamps HL is transmitted through the lower chamber window 64 and the susceptor 74, which are made of quartz, and is irradiated onto the lower surface of the semiconductor wafer W. The semiconductor wafer W is preheated by being irradiated with light from the halogen lamps HL, and the temperature rises.

[0079] The temperature of the semiconductor wafer W, which is heated by the light irradiation from the halogen lamps HL, is measured by the edge radiation thermometer 20. The measured value Ip4 output from the edge radiation thermometer 20 when the semiconductor wafer W is being heated, is expressed by the following equation (8). Because the semiconductor wafer W is placed on the susceptor 74 when the semiconductor wafer W is being heated, the components of the light incident on the edge radiation thermometer 20 are the same as those expressed by equation (4). That is, in addition to the light emitted from the semiconductor wafer W being heated, the edge radiation thermometer 20 is also subjected to disturbance light including transmitted light emitted from the upper chamber window 63 and transmitted through the semiconductor wafer W, and reflected light emitted from the lower chamber window 64 and reflected by the back surface of the semiconductor wafer W.

[0080]

number

[0081] Silicon (Si), the material of the semiconductor wafer W, has the property that its transmittance decreases as its temperature rises. When the temperature of the semiconductor wafer W reaches 600°C or higher, the transmittance tw of the semiconductor wafer W approaches 0, and therefore the transmitted light emitted from the upper chamber window 63 and transmitted through the semiconductor wafer W can be ignored. In other words, the main component of the disturbance light incident on the edge radiation thermometer 20 is the reflected light emitted from the lower chamber window 64 and reflected by the back surface of the semiconductor wafer W. Therefore, the following equation (9) holds true:

[0082]

number

[0083] That is, the intensity Iw of the radiant light emitted from the semiconductor wafer W during heat treatment is calculated by subtracting the intensity of the light reflected from the lower chamber window 64, which is ambient light, from the measurement value Ip4 of the edge radiation thermometer 20. The intensity of the light emitted from the lower chamber window 64 and reflected by the back surface of the semiconductor wafer W is the product of the reflectance rw of the back surface of the semiconductor wafer W and the intensity Ilw of the radiant light emitted from the lower chamber window 64. The reflectance rw of the back surface of the semiconductor wafer W is calculated using equation (7) in step S5. The intensity Ilw of the radiant light emitted from the lower chamber window 64 gradually changes during the heat treatment of the semiconductor wafer W by absorbing a portion of the light irradiated from the halogen lamps HL. In the first embodiment, this gradually changing intensity Ilw of the radiant light emitted from the lower chamber window 64 is calculated using the mathematical model described above.

[0084] The control unit 3 inputs the lamp power of the halogen lamp HL, which changes over time, into the above mathematical model to estimate the intensity Ilw of the light emitted from the lower chamber window 64, which changes sequentially. Then, the control unit 3 multiplies the determined intensity Ilw by the reflectance rw of the back surface of the semiconductor wafer W to calculate the intensity of the light reflected from the lower chamber window 64, which is ambient light (step S7).

[0085] Next, the control unit 3 calculates the intensity Iw of the radiant light emitted from the semiconductor wafer W during the heat treatment by subtracting the intensity of the disturbance light from the measurement value Ip4 of the edge radiation thermometer 20 based on equation (9). The intensity Iw calculated from equation (9) is the true intensity of the radiant light emitted from the semiconductor wafer W, from which the effects of disturbance light have been eliminated. The control unit 3 performs a predetermined arithmetic process on the intensity Iw of the radiant light calculated from equation (9) to calculate the temperature of the semiconductor wafer W (step S8). The control unit 3 may store the calculated temperature of the semiconductor wafer W in a memory unit and display it on a display unit such as a liquid crystal display.

[0086] The temperature of the semiconductor wafer W changes over time as the heat treatment progresses. In addition, the temperature of the lower chamber window 64, which is a source of ambient light, also changes over time. For this reason, the temperature of the semiconductor wafer W is repeatedly calculated until the heat treatment is completed. Specifically, the processes of steps S7 and S8 are repeated until the heat treatment of the semiconductor wafer W is completed (step S9).

[0087] The control unit 3 controls the output of the halogen lamps HL while monitoring whether the temperature of the semiconductor wafer W, which is increased 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 so that the temperature of the semiconductor wafer W calculated in step S8 becomes the preheating temperature T1.

[0088] 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 calculated in step S8 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.

[0089] 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.

[0090] 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. 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.

[0091] Flash heating is performed by irradiating a flash of light (flash of light) from flash lamps FL, which can raise the surface temperature of the semiconductor wafer W in a short time. That is, the flash of light irradiated from the flash lamps FL is an extremely short, intense flash of light with an irradiation time of approximately 0.1 milliseconds to 100 milliseconds, in which electrostatic energy previously stored in a capacitor is converted into an extremely short light pulse. The surface temperature of the semiconductor wafer W flash-heated by the irradiation of the flash of light from the flash lamps FL instantaneously rises to a processing temperature T2 of 1000°C or higher and then rapidly drops.

[0092] 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 drop from the preheating temperature T1. After the temperature of the semiconductor wafer W drops below a predetermined level, 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 transferred out of the chamber 6 by a transfer robot external to the apparatus, completing the heat treatment of the semiconductor wafer W (step S10).

[0093] In the first embodiment, the reflectance rw of the semiconductor wafer W loaded into the chamber 6 is measured, and the intensity of the disturbance light incident on the edge radiation thermometer 20 is calculated based on the reflectance rw and the intensity Ilw of the light emitted from the lower chamber window 64. Then, the temperature of the semiconductor wafer W is calculated by subtracting the intensity of the disturbance light from the intensity of the light received by the edge radiation thermometer 20 during the heat treatment of the semiconductor wafer W (measured value Ip4).

[0094] Another possible approach is to measure the reflectance of the semiconductor wafer W in advance using a dedicated reflectance measurement mechanism in a separate chamber (e.g., an alignment chamber for adjusting the orientation of the semiconductor wafer W) before loading the semiconductor wafer W into the chamber 6. However, differences in the ambient environment within the chamber (e.g., the installation angle of the radiation thermometer) can result in different measured reflectances. In this embodiment, the reflectance of the semiconductor wafer W is measured in an environment identical to the actual heat treatment environment after the semiconductor wafer W is loaded into the chamber 6, thereby enabling a more accurate reflectance of the semiconductor wafer W in the heat treatment environment to be obtained. As a result, the intensity of the ambient light incident on the edge radiation thermometer 20 can be accurately calculated, allowing the temperature of the semiconductor wafer W to be measured with higher accuracy. Accurate measurement of the temperature of the semiconductor wafer W can improve the accuracy of temperature control of the semiconductor wafer W, for example, during preheating.

[0095] Furthermore, in the first embodiment, a mathematical model is constructed that represents the relationship between the lamp power of the multiple halogen lamps HL and the intensity Ilw of the radiant light emitted from the lower chamber window 64, and the intensity Ilw of the radiant light emitted from the lower chamber window 64, which changes over time, is determined from the mathematical model. This makes it possible to more appropriately calculate the intensity of ambient light, which changes over time, and to more accurately measure the temperature of the semiconductor wafer W.

[0096] Second Embodiment Next, a second embodiment of the present invention will be described. In the first embodiment, the intensity Ilw of the radiant light emitted from the lower chamber window 64 is calculated from a mathematical model, whereas in the second embodiment, the intensity Ilw of the radiant light emitted from the lower chamber window 64 is calculated by actual measurement.

[0097] FIG. 12 is a longitudinal cross-sectional view showing the configuration of a heat treatment apparatus 1a according to the second embodiment. In FIG. 12, the same elements as those in the heat treatment apparatus 1 (FIG. 1) according to the first embodiment are assigned the same reference numerals. The heat treatment apparatus 1a according to the second embodiment differs from the first embodiment in that it includes a lower window radiation thermometer 29. The lower window radiation thermometer 29 is provided, for example, between the chamber 6 and the halogen heating unit 4. The lower window radiation thermometer 29 receives radiation emitted from a lower chamber window 64 to measure the temperature of the lower chamber window 64. The remaining configuration of the heat treatment apparatus 1a, except for the lower window radiation thermometer 29, is the same as that according to the first embodiment.

[0098] The processing operation in the heat treatment apparatus 1a of the second embodiment is also generally similar to that of the first embodiment (FIG. 8). However, in the second embodiment, when calculating the reflectance rw of the semiconductor wafer W from equation (7) in step S5, the intensity Ilw of the radiant light emitted from the lower chamber window 64 is used as the actual measurement value of the lower window radiation thermometer 29. That is, the control unit 3 calculates the reflectance rw of the semiconductor wafer W from equation (7) using the actual measurement values ​​of the lower window radiation thermometer 29, the edge radiation thermometer 20, and the center radiation thermometer 25.

[0099] Furthermore, in the second embodiment, when calculating the intensity of the ambient light in step S7, the intensity Ilw of the radiant light emitted from the lower chamber window 64, which changes sequentially, is used as the actual measurement value of the lower window radiation thermometer 29. The control unit 3 calculates the intensity of the reflected light from the lower chamber window 64, which is ambient light, by multiplying the actual measurement value of the lower window radiation thermometer 29 by the reflectance rw of the back surface of the semiconductor wafer W. The control unit 3 then calculates the intensity Iw of the radiant light radiated from the semiconductor wafer W during heat treatment by subtracting the intensity of the ambient light from the measurement value Ip4 of the edge radiation thermometer 20, and calculates the temperature of the semiconductor wafer W.

[0100] In the second embodiment, the intensity Ilw of radiant light emitted from the lower chamber window 64, which changes sequentially, is determined based on the actual measurement value by the lower window radiation thermometer 29. Then, the intensity of disturbance light incident on the edge radiation thermometer 20 is calculated based on the radiant light intensity Ilw determined by the actual measurement by the measuring device and the reflectance rw of the semiconductor wafer W, and the temperature of the semiconductor wafer W during heat treatment is calculated. Therefore, the intensity of disturbance light incident on the edge radiation thermometer 20, which changes sequentially, can be accurately calculated, and the temperature of the semiconductor wafer W can be measured with high precision.

[0101] <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 and second embodiments, the intensity Ilw of the radiant light emitted from the lower chamber window 64 is calculated, and the light reflected from the lower chamber window 64 is treated as disturbance light incident on the edge radiation thermometer 20 to calculate its intensity. However, this is not limited to this. Alternatively, a radiation thermometer may be provided above the semiconductor wafer W, and the light emitted from the upper chamber window 63 and reflected by the surface of the semiconductor wafer W may be treated as disturbance light incident on the radiation thermometer. In this case, the intensity of the radiant light emitted from the upper chamber window 63 is calculated, and the intensity of the disturbance light is calculated based on the intensity of the radiant light emitted from the upper chamber window 63 and the reflectance of the surface of the semiconductor wafer W.

[0102] Furthermore, in the first embodiment, a transfer function is used as a mathematical model for estimating the intensity Ilw of radiant light emitted from the lower chamber window 64. However, the present invention is not limited to this, and other models may be used, such as a state space representation, an ARX (Auto-Regressive with eXogenous) model, a nonlinear ARX model, or a neural network. In other words, any mathematical model may be used as long as it can output the intensity Ilw of radiant light emitted from the lower chamber window 64, which changes sequentially.

[0103] In the second embodiment, the intensity Ilw of the radiant light emitted from the lower chamber window 64 may be actually measured by the lower window radiation thermometer 29 and may also be calculated from a mathematical model as in the first embodiment, and if the difference between the measured values ​​exceeds a preset threshold, the control unit 3 may determine that an abnormality has occurred and stop the heating process.

[0104] The technology according to the present invention may be applied when two or more semiconductor wafers W are successively heat-treated and the temperature of each of the semiconductor wafers W is measured. Rather, the technology according to the present invention is suitable for measuring the temperature of the second and subsequent semiconductor wafers W when a plurality of semiconductor wafers W constituting a lot are successively loaded one by one into the chamber 6 and heat-treated. The reason for this is that when the second and subsequent semiconductor wafers W are processed, the temperature of the lower chamber window 64 and the like rises and the intensity of ambient light increases.

[0105] 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.

[0106] 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]

[0107] 1. Heat treatment equipment 3. Control Unit 4 Halogen heating section 5 Flash heating section 6 chambers 7 Holding part 10 Transfer mechanism 12 lift pins 20 Edge radiation thermometer 25 Central radiation thermometer 29 Lower window radiation thermometer 63 Upper chamber window 64 Lower chamber window 65 Heat Treatment Space 74 Susceptor 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 reflectance measurement step of measuring the reflectance of the substrate carried into the chamber; a disturbance light calculation step of calculating the intensity of disturbance light incident on a radiation thermometer that measures the temperature of the substrate, based on the reflectance measured in the reflectance measurement step and the intensity of radiation light emitted from a quartz window provided in the chamber; a substrate temperature calculation step of calculating a temperature of the substrate by subtracting the intensity of the ambient light from the intensity of the light received by the radiation thermometer while the substrate is being heated by light irradiation; A temperature measurement method comprising:

2. 2. The temperature measurement method according to claim 1, A temperature measurement method characterized in that in the ambient light calculation step, the intensity of the ambient light is calculated based on the intensity of the radiated light from the quartz window, which changes sequentially when the substrate is heated by light irradiation.

3. 3. The temperature measurement method according to claim 1 or 2, The temperature measuring method according to claim 1, wherein the intensity of the light emitted from the quartz window is determined by measurement using a measuring instrument.

4. 3. The temperature measurement method according to claim 1 or 2, A temperature measuring method characterized in that the intensity of the radiation from the quartz window is determined from a mathematical model.

5. 2. The temperature measurement method according to claim 1, a temperature measuring method characterized in that, in the reflectance measuring step, the reflectance is calculated based on the intensity of light received by the radiation thermometer when the substrate carried into the chamber is supported at a distance from a susceptor, the intensity of light received by the radiation thermometer when the substrate is placed on the susceptor, and the intensity of light emitted from the susceptor.

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