Heat treatment apparatus and heat treatment method

Abstract

To provide a heat treatment apparatus and heat treatment method in which treatment gas can be instantly supplied into a chamber.SOLUTION: After preliminary heating is performed by light irradiation a semiconductor wafer W housed in a chamber 6 from a halogen lamp, flash light is irradiated with from a flash lamp. Before flash light irradiation, ozone is stored in a gas storage tank 152 and the inside of the gas storage tank 152 is in a higher pressure than the atmospheric pressure. On the other hand, the inside of the chamber 6 is decompressed in a lower pressure than the atmospheric pressure. In this state, from a point where the flash lamp turns on to start flash light irradiation to a point where the surface temperature of the semiconductor wafer reaches the peak temperature, an air supply valve 153 is opened. Ozone gas flows at once toward the chamber 6 from the gas storage tank 152, and ozone gas can be instantly supplied into the chamber 6.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a heat treatment apparatus and a heat treatment method for heating a substrate by irradiating the substrate with flash light. Examples of substrates to be treated include 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] Attempts have also been made to apply flash lamp annealing to oxide film formation (Patent Document 1). Flash lamp annealing is suitable for forming thin oxide films with good properties because it can heat the surface of a semiconductor wafer to high temperatures in an extremely short time. In the technology disclosed in Patent Document 1, in order to prevent the formation of poor-quality oxide films at low temperatures, the initial stage of heating is carried out in a nitrogen atmosphere, and once the semiconductor wafer has reached a certain temperature, an oxidizing gas such as oxygen is supplied to switch the atmosphere in the chamber from the nitrogen atmosphere to an oxidizing atmosphere. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-145366 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in recent years, requirements for the thickness and quality of oxide films have become increasingly stringent, necessitating oxidation in higher temperature regions only. Specifically, it is considered ideal to carry out the oxidation reaction only in the peak temperature region during flash light irradiation. To achieve this, it is necessary to supply a large amount of oxidizing gas instantaneously during flash light irradiation, but conventional gas control has not been able to achieve such a gas supply.

[0008] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a heat treatment apparatus and a heat treatment method that can instantly supply a processing gas into a chamber. [Means for solving the problem]

[0009] In order to solve the above problems, a first aspect of the present invention is a heat treatment apparatus that heats a substrate by irradiating the substrate with a flash light, the heat treatment apparatus comprising: a chamber that accommodates a substrate; a flash lamp that irradiates a surface of the substrate accommodated in the chamber with a flash light to raise the temperature of the surface of the substrate to a predetermined processing temperature; a gas supply unit that supplies a processing gas into the chamber; an exhaust unit that exhausts gas from the chamber to reduce the pressure inside the chamber; and a control unit that controls the gas supply unit and the exhaust unit, wherein the gas supply unit includes a gas storage unit that stores the processing gas and an air intake valve provided in a pipe that connects the gas storage unit to the chamber, and the control unit controls the gas supply unit so that the air intake valve opens at a predetermined timing when the pressure inside the gas storage unit is higher than atmospheric pressure and the pressure inside the chamber is reduced to a pressure lower than atmospheric pressure.

[0010] In a second aspect, in the heat treatment apparatus according to the first aspect, the control unit controls the gas supply unit so that the air supply valve opens between the time when the flash lamp is turned on and flash light irradiation begins and the time when the surface of the substrate reaches the processing temperature.

[0011] In a third aspect, in the heat treatment apparatus according to the second aspect, the control unit controls the gas supply unit so that the air intake valve closes within one second after the air intake valve opens.

[0012] In addition, a fourth aspect is a heat treatment apparatus according to any one of the first to third aspects, wherein the gas supply unit further includes an exhaust valve provided in an exhaust pipe from the gas storage unit, and the exhaust valve maintains the pressure inside the gas storage unit at a pressure higher than atmospheric pressure.

[0013] A fifth aspect is the heat treatment apparatus according to any one of the first to fourth aspects, wherein the process gas is one gas selected from the group consisting of oxygen, ozone, ammonia, nitrogen, and argon.

[0014] In addition, a sixth aspect is a heat treatment method for heating a substrate by irradiating the substrate with flash light, the method comprising: a storage step of storing the substrate in a chamber; an irradiation step of irradiating a surface of the substrate stored in the chamber with flash light from a flash lamp to raise the temperature of the surface of the substrate to a predetermined processing temperature; an exhaust step of evacuating gas from the chamber to reduce the pressure inside the chamber to a pressure lower than atmospheric pressure; and a storage step of storing processing gas in a gas storage unit to increase the pressure inside the gas storage unit to a pressure higher than atmospheric pressure, wherein, when the pressure inside the gas storage unit is higher than atmospheric pressure and the pressure inside the chamber is reduced to a pressure lower than atmospheric pressure, an air intake valve provided on a pipe connecting the gas storage unit to the chamber is opened at a predetermined timing.

[0015] In addition, a seventh aspect is the heat treatment method according to the sixth aspect, wherein the air supply valve is opened during the period from when the flash lamp is turned on and flash light irradiation is started until the surface of the substrate reaches the treatment temperature.

[0016] In an eighth aspect, in the heat treatment method according to the seventh aspect, the air intake valve is closed within one second after it is opened.

[0017] In addition, a ninth aspect is a heat treatment method according to any one of the sixth to eighth aspects, wherein an exhaust valve provided in an exhaust pipe extending from the gas storage section maintains the inside of the gas storage section at a pressure higher than atmospheric pressure.

[0018] A tenth aspect is the heat treatment method according to any one of the sixth to ninth aspects, wherein the treatment gas is one gas selected from the group consisting of oxygen, ozone, ammonia, nitrogen, and argon. [Effects of the Invention]

[0019] In the heat treatment apparatus according to the first to fifth aspects, the pressure inside the gas storage unit is set to be higher than atmospheric pressure and the pressure inside the chamber is reduced to be lower than atmospheric pressure, and the air intake valve opens at a predetermined timing. This allows the processing gas to flow from the pressurized gas storage unit to the reduced-pressure chamber all at once, allowing the processing gas to be supplied instantly into the chamber.

[0020] In particular, in the heat treatment apparatus according to the second aspect, the air supply valve opens between the time when the flash lamp is turned on and flash light irradiation begins and the time when the surface of the substrate reaches the processing temperature, so that processing gas can be supplied the moment the surface of the substrate reaches the processing temperature.

[0021] According to the heat treatment methods of the sixth to tenth aspects, the pressure inside the gas storage unit is set to be higher than atmospheric pressure and the pressure inside the chamber is reduced to be lower than atmospheric pressure, and an air intake valve provided on a pipe connecting the gas storage unit and the chamber is opened at a predetermined timing. As a result, the processing gas flows all at once from the pressurized gas storage unit to the reduced-pressure chamber, and the processing gas can be supplied instantly into the chamber.

[0022] In particular, according to the heat treatment method of the seventh aspect, the air supply valve is opened between the time when the flash lamp is turned on and flash light irradiation begins and the time when the surface of the substrate reaches the treatment temperature, so that treatment gas can be supplied the moment the surface of the substrate reaches the treatment temperature. [Brief explanation of the drawings]

[0023] [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 diagram schematically illustrating an air supply / exhaust mechanism for a chamber. [Figure 9] 2 is a flowchart showing a processing procedure for a semiconductor wafer in the heat treatment apparatus of FIG. 1. [Figure 10] FIG. 10 is a diagram showing the transition of the pressure in the chamber and the surface temperature of the semiconductor wafer. [Figure 11] FIG. 10 is a diagram showing changes in the surface temperature of a semiconductor wafer before and after irradiation with flash light. [Figure 12] FIG. 10 is a diagram schematically illustrating the phenomenon that occurs in the chamber the moment the air intake valve is opened. DETAILED DESCRIPTION OF THE INVENTION

[0024] 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."

[0025] 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.

[0026] The 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 the chamber 6, and the halogen heating unit 4 is provided below it. The heat treatment apparatus 1 also includes, inside the chamber 6, a holder 7 that holds the semiconductor wafer W in a horizontal position, a transfer mechanism 10 that transfers the semiconductor wafer W between the holder 7 and the outside of the apparatus, and a shower plate 30. The heat treatment apparatus 1 also includes a control unit 3 that controls the operating mechanisms provided in the halogen heating unit 4, the flash heating unit 5, and the chamber 6 to perform heat treatment on the semiconductor wafer W.

[0027] 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.

[0028] Additionally, a gas ring 90 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 the gas ring 90 and the reflective ring 69 are formed in an annular shape. The inner 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, the reflective ring 69, and the gas ring 90, is defined as the heat treatment space 65.

[0029] By attaching the reflecting ring 69 and the gas ring 90 to the chamber side section 61, a recess 62 is formed on the inner wall surface of the chamber 6. That is, the recess 62 is formed by the central portion of the inner wall surface of the chamber side section 61 where the reflecting ring 69 and the gas ring 90 are not attached, the upper end surface of the reflecting ring 69, and the lower end surface of the gas ring 90. 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.

[0030] 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.

[0031] 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 a barium fluoride material or a calcium 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.

[0032] A gas ring 90 attached to the upper part of the inner wall of the chamber 6 is formed with a gas supply port 81 for supplying a processing gas to the heat treatment space 65. The gas supply port 81 is connected to a gas supply pipe 83 via a flow path formed inside the gas ring 90. The gas supply pipe 83 is connected to a gas supply unit 150. Meanwhile, a gas exhaust hole 86 for exhausting gas from the heat treatment space 65 is formed in the lower part of the inner wall of the chamber 6. 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. In this embodiment, gas is supplied from above the semiconductor wafer W held by the holder 7 in the chamber 6 and exhausted from below the semiconductor wafer W. Details of the supply and exhaust mechanism for the chamber 6 will be described later.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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 200 mm to 280 mm. 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] FIG. 8 is a schematic diagram showing the supply and exhaust mechanism for the chamber 6. A gas ring 90 and a shower plate 30 are provided in the upper part of the chamber 6. The gas ring 90, which is attached to the upper part of the inner wall surface of the roughly cylindrical chamber side part 61, has an annular shape. The gas ring 90 is attached so that its center coincides with the center of the chamber side part 61. In other words, the radial and circumferential directions of the gas ring 90 coincide with the radial and circumferential directions of the chamber side part 61. The gas ring 90 includes an upper ring 91 and a lower ring 92. Both the upper ring 91 and the lower ring 92 have an annular shape. The upper ring 91 and the lower ring 92 are stacked together to form the gas ring 90.

[0045] In the structure in which annular upper ring 91 and lower ring 92 are stacked together, a gap is formed between upper ring 91 and lower ring 92, and this gap serves as the flow path of gas ring 90. This flow path may have a buffer or labyrinth structure that can act as a resistance to the gas flow. The end of this flow path facing the inside of chamber 6 serves as gas supply port 81. The other end of this flow path is connected to gas supply pipe 83. Gas supply pipe 83 is connected to gas supply unit 150.

[0046] The shower plate 30 is a disk-shaped member made of quartz. Therefore, like the upper chamber window 63, the shower plate 30 transmits the flash light emitted from the flash heating unit 5. The shower plate 30 has a plurality of ejection holes 31 drilled therethrough from top to bottom. The size of the area in which the plurality of ejection holes 31 are provided is, for example, approximately the same as the planar size of a semiconductor wafer W. The diameter of each ejection hole 31 is approximately several millimeters. The diameter of the plurality of ejection holes 31 is not limited to being uniform; for example, the diameter may be gradually reduced from the center of the shower plate 30 toward the periphery.

[0047] 8, the circular plate-shaped shower plate 30 is mounted in the chamber 6 with its peripheral edge supported by the lower ring 92 of the gas ring 90. Therefore, the shower plate 30 is provided above the holder 7. When the shower plate 30 is mounted in the chamber 6, a space is formed between the upper chamber window 63 and the shower plate 30.

[0048] The process gas supplied from the gas supply unit 150 to the gas ring 90 via the gas supply pipe 83 passes through a flow path in the gas ring 90 and is supplied from the gas supply port 81 to the space between the upper chamber window 63 and the shower plate 30. The process gas is ejected downward from the multiple ejection holes 31 provided in the shower plate 30. The process gas ejected in a shower-like manner from the shower plate 30 forms a downflow of the process gas in the heat treatment space 65, flowing from above to below.

[0049] The gas supply unit 150 includes an ozone generator 151, a gas storage tank 152, an intake valve 153, and an exhaust valve 154. The ozone generator 151 generates ozone (O3), for example, by irradiating oxygen (O2) with ultraviolet light or by discharging electricity in oxygen. The ozone generator 151 sends the generated ozone to a gas storage tank 152. The gas storage tank 152 is a buffer tank that temporarily stores the ozone sent from the ozone generator 151. When the volume of the chamber 6 is, for example, 25 liters, the volume of the gas storage tank 152 is, for example, 1 to 2 liters. The gas storage tank 152 is provided with a pressure sensor 157. The pressure sensor 157 measures the pressure of the ozone stored in the gas storage tank 152.

[0050] The gas supply pipe 83 is a pipe that connects the gas storage tank 152 and the gas ring 90 of the chamber 6. An intake valve 153 is provided on the gas supply pipe 83. When the intake valve 153 is opened, the ozone gas stored in the gas storage tank 152 is supplied to the chamber 6.

[0051] An exhaust pipe 155 branches off and is connected to the gas supply pipe 83 midway between the gas storage tank 152 and the air intake valve 153. An exhaust valve 154 is provided on the exhaust pipe 155. When the exhaust valve 154 is opened, the ozone gas stored in the gas storage tank 152 is discharged to the outside of the apparatus. Note that the air intake valve 153 and the exhaust valve 154 are preferably valves with a fast response speed, and for example, electromagnetic valves can be used.

[0052] In addition, a nitrogen (N2) supply line is connected to the gas supply pipe 83 midway between the intake valve 153 and the gas ring 90. Nitrogen gas delivered from this supply line flows through the gas supply pipe 83 and is supplied to the chamber 6.

[0053] The intake valve 153 and the exhaust valve 154 are selectively opened. That is, when the intake valve 153 is opened, the exhaust valve 154 is closed. Conversely, when the exhaust valve 154 is opened, the intake valve 153 is closed.

[0054] Meanwhile, the gas exhaust pipe 88 is connected to an exhaust unit 190. The exhaust unit 190 includes a main valve 191, an automatic pressure controller (APC) 192, and a vacuum pump 193. When the main valve 191 is opened while the vacuum pump 193 is operating, the gas inside the chamber 6 is exhausted through the gas exhaust pipe 88. When the flow rate of gas exhausted from the chamber 6 by the exhaust unit 190 is greater than the flow rate of gas supplied from the gas ring 90 into the chamber 6, the pressure inside the chamber 6 is reduced to below atmospheric pressure. Even if pressure fluctuations occur during the decompression of the chamber 6, the automatic pressure control valve 192 eliminates the pressure fluctuations and maintains a constant pressure inside the chamber 6.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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 or SSD) 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 controls the gas supply unit 150 and the exhaust unit 190, and more specifically, controls the opening and closing of the intake valve 153, the exhaust valve 154, and the main valve 191.

[0066] 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.

[0067] Next, a processing procedure for a semiconductor wafer W in the heat treatment apparatus 1 will be described. FIG. 9 is a flowchart showing the processing procedure for a semiconductor wafer W. In this embodiment, the substrate to be processed is a silicon (Si) semiconductor wafer W. At least a portion of the silicon base material is exposed on the surface of the semiconductor wafer W. Prior to the heat treatment method according to the present invention, the surface of the semiconductor wafer W may be subjected to a cleaning process using hydrofluoric acid or the like to remove any native oxide film formed on the exposed silicon portions.

[0068] First, a silicon semiconductor wafer W is loaded into the chamber 6 of the heat treatment apparatus 1 (step S1). Specifically, the gate valve 185 is opened to open the transfer opening 66, and the semiconductor wafer W is loaded into the heat treatment space 65 in the chamber 6 through the transfer opening 66 by a transfer robot external to the apparatus. At this time, nitrogen gas may be supplied from the gas ring 90 into the chamber 6 and allowed to flow out from the transfer opening 66 to minimize the entrainment of external atmosphere during the loading of the semiconductor wafer W.

[0069] 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.

[0070] 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 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 held on the holder 7 with its front surface, some of which has exposed silicon, 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.

[0071] After the transfer opening 66 is closed by the gate valve 185 to make the heat treatment space 65 a sealed space, nitrogen is supplied into the chamber 6 while evacuating the chamber 6, thereby reducing the pressure inside the chamber 6 (step S2). That is, while nitrogen is supplied into the chamber 6 from the gas ring 90, the main valve 191 is opened with the vacuum pump 193 operating, and the chamber 6 is evacuated. At this time, because the exhaust flow rate from the chamber 6 is significantly greater than the nitrogen supply flow rate into the chamber 6, the pressure inside the chamber 6 drops rapidly and is reduced to below atmospheric pressure. The pressure inside the chamber 6 is reduced to, for example, approximately 5 kPa. As a result, a low-pressure nitrogen atmosphere is formed inside the chamber 6.

[0072] Next, the 40 halogen lamps HL of the halogen heating unit 4 are simultaneously turned on to begin preheating (assisted heating) (step S3). FIG. 10 shows the changes in the pressure inside the chamber 6 and the surface temperature of the semiconductor wafer W. After the pressure inside the chamber 6 is reduced to approximately 5 kPa at time t1, the halogen lamps HL are turned on to begin preheating the semiconductor wafer W. The halogen light emitted from the halogen lamps HL passes through the lower chamber window 64 and susceptor 74, both made of quartz, and is irradiated onto the underside of the semiconductor wafer W. The semiconductor wafer W is preheated by the light irradiation 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.

[0073] When preheating is performed using the halogen lamps HL, the temperature of the semiconductor wafer W is measured by the radiation thermometer 20. That is, the radiation thermometer 20 receives infrared light radiated from the underside of the semiconductor wafer W held on the susceptor 74 through the openings 78 and receives it through the transparent window 21 to measure the wafer temperature during heating. The measured temperature of the semiconductor wafer W is transmitted to the control unit 3. The control unit 3 controls the output of the halogen lamps HL while monitoring whether the temperature of the semiconductor wafer W, which is heated by 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 value measured by the radiation thermometer 20 so that the temperature of the semiconductor wafer W becomes the preheating temperature T1. The preheating temperature T1 is, for example, 800°C.

[0074] 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, at time t2 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.

[0075] 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. However, 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. This increases the amount of light irradiated onto the peripheral portion of the semiconductor wafer W, where heat dissipation is more likely, thereby achieving a uniform in-plane temperature distribution of the semiconductor wafer W during the preheating stage. During the preheating process using the halogen lamps HL, the pressure inside the chamber 6 is reduced to below atmospheric pressure, creating a low-pressure nitrogen atmosphere, thereby suppressing oxidation reactions on the surface of the semiconductor wafer W.

[0076] In parallel with the decompression of the chamber 6 and the preheating of the semiconductor wafer W, gas is stored in the gas storage tank 152 (step S4). That is, steps S2, S3, and S4 are processes that are executed in parallel. The ozone generator 151 continuously generates ozone and continuously supplies ozone to the gas storage tank 152 at a constant flow rate. In order to supply ozone from the ozone generator 151 to the gas storage tank 152 at a constant flow rate, a mass flow controller (MFC) may be provided in the piping between the ozone generator 151 and the gas storage tank 152. The ozone supplied from the ozone generator 151 is temporarily stored in the gas storage tank 152.

[0077] Except when ozone is being supplied to the chamber 6, the intake valve 153 is closed and the exhaust valve 154 is open. Therefore, the ozone stored in the gas storage tank 152 is continuously exhausted through the exhaust pipe 155. That is, newly generated ozone is continuously supplied to the gas storage tank 152, while ozone is continuously exhausted from the gas storage tank 152. By setting the aperture of the exhaust valve 154 to an appropriate value, ozone can be stored in the gas storage tank 152 at a constant pressure. In this embodiment, ozone is stored in the gas storage tank 152 at a pressure higher than atmospheric pressure, for example, 0.2 MPa. That is, the exhaust valve 154 maintains the pressure inside the gas storage tank 152 at a pressure higher than atmospheric pressure. Note that the control unit 3 may perform feedback control of the aperture of the exhaust valve 154 based on the pressure inside the gas storage tank 152 measured by the pressure sensor 157 so that the pressure inside the gas storage tank 152 is constant and higher than atmospheric pressure.

[0078] At time t3, 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. The flash light emitted from the flash lamps FL is transmitted in order through the lamp light emission window 53, the upper chamber window 63, and the shower plate 30, all of which are made of quartz, and is irradiated onto the surface of the semiconductor wafer W, thereby flash heating the semiconductor wafer W.

[0079] FIG. 11 shows the change in the surface temperature of a semiconductor wafer W before and after flash light irradiation. At time t32, the flash lamps FL are turned on, and flash light irradiation begins (step S5). The flash light emitted from the flash lamps FL is an extremely short, intense flash with an irradiation time of approximately 0.1 milliseconds to 100 milliseconds, resulting from electrostatic energy previously stored in a capacitor being converted into an extremely short light pulse. Therefore, the surface temperature of the semiconductor wafer W irradiated with the flash light rises rapidly in a short period of time and reaches a processing temperature T2 at time t34. The processing temperature T2 is, for example, 1200°C. The time from time t32, when flash light irradiation begins, to time t34, when the surface temperature of the semiconductor wafer W reaches the peak processing temperature T2 (the temperature rise time due to flash heating) is several milliseconds to several tens of milliseconds. Note that the horizontal scale in FIG. 11 is a significantly enlarged version of that in FIG. 10, and times t32 to t34 in FIG. 11 are displayed superimposed on time t3 in FIG. 10.

[0080] At time t33, which occurs between time t32 when the flash lamps FL are turned on and flash light irradiation begins and time t34 when the surface temperature of the semiconductor wafer W reaches the processing temperature T2, the air intake valve 153 is opened and the exhaust valve 154 is closed (step S6). Specifically, since a certain amount of time (one second or less) is required for communication and valve operation after the control unit 3 issues a signal to open or close the valves, the control unit 3 issues a signal to open the air intake valve 153 and close the exhaust valve 154 at time t31, which is before time t32 when the flash lamps FL are turned on. Time t33, when the signal is transmitted via communication and the air intake valve 153 actually opens and the exhaust valve 154 closes, is between time t32 when flash light irradiation begins and time t34 when the surface temperature of the semiconductor wafer W reaches the peak temperature (processing temperature T2).

[0081] 12 is a diagram schematically illustrating a phenomenon occurring in the chamber 6 the moment the air intake valve 153 is opened. At time t32 when flash light irradiation starts (i.e., immediately before the air intake valve 153 is opened), the pressure inside the gas storage tank 152 is higher than atmospheric pressure (e.g., 0.2 MPa), and the pressure inside the chamber 6 is reduced to a pressure lower than atmospheric pressure (e.g., 5 kPa). When the air intake valve 153 is opened at time t33 in this state, ozone gas flows in one go from the gas storage tank 152, which is pressurized higher than atmospheric pressure, to the chamber 6, which is reduced to a pressure lower than atmospheric pressure. As a result, a large amount of ozone gas is supplied instantaneously into the chamber 6. The ozone gas supplied from the gas storage tank 152 passes through the flow path of the gas ring 90 and flows into the space between the upper chamber window 63 and the shower plate 30. From there, the ozone gas is ejected downward through the multiple ejection holes 31 and sprayed onto the semiconductor wafer W held on the susceptor 74. The pressure inside the chamber 6 is maintained at a substantially constant value (5 kPa in the above example) by the automatic pressure control valve 192 even when the ozone gas flows in instantaneously.

[0082] 11, because the flash irradiation time is extremely short, approximately 0.1 milliseconds to 100 milliseconds, the surface temperature of the semiconductor wafer W reaches its peak temperature at time t34 and then drops rapidly. Furthermore, at time t35, which is after time t34 when the surface temperature of the semiconductor wafer W reaches its peak temperature and is within one second of time t33 when the air intake valve 153 is opened, the air intake valve 153 is closed and the exhaust valve 154 is opened (step S7). This stops the supply of ozone to the chamber 6. Therefore, ozone is supplied to the chamber 6 only between time t33 and time t35, just before and after the surface temperature of the semiconductor wafer W reaches its peak temperature due to the flash irradiation.

[0083] Ozone is supplied only before and after the surface temperature of the semiconductor wafer W reaches its peak temperature (peak temperature region) during flash light irradiation, causing oxidation of the exposed silicon on the surface of the semiconductor wafer W, forming a silicon oxide film (a thin film of silicon dioxide (SiO2)). Because the time that ozone is supplied to the periphery of the semiconductor wafer W is short, less than one second, the thickness of the silicon oxide film that is formed is approximately 10 angstroms.

[0084] At time t34, after a predetermined time has elapsed since the surface temperature of the semiconductor wafer W reached the processing temperature T2, the halogen lamps HL are also turned off. As a result, the temperature of the semiconductor wafer W also drops from the preheating temperature T1. The temperature of the semiconductor wafer W during the temperature drop is measured by the radiation thermometer 20, and the measurement result is transmitted to the control unit 3. Furthermore, even after the supply of ozone to the chamber 6 is stopped at time t35, the exhaust unit 190 continues to exhaust air from the chamber 6. As a result, any remaining ozone is discharged from the chamber 6.

[0085] After the temperature of the semiconductor wafer W drops below a predetermined temperature and the ozone inside the chamber 6 has been sufficiently discharged, exhaust from the chamber 6 is stopped at time t4 (FIG. 10), and nitrogen is supplied into the chamber 6, so that the pressure inside the chamber 6 returns to atmospheric pressure. Thereafter, 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 carried out by a transfer robot outside the apparatus (step S8), completing the heat treatment of the semiconductor wafer W in the heat treatment apparatus 1.

[0086] In this embodiment, the control unit 3 controls the gas supply unit 150 so that the pressure inside the gas storage tank 152 is higher than atmospheric pressure during flash light irradiation and the air intake valve 153 is opened when the pressure inside the chamber 6 is reduced to a pressure lower than atmospheric pressure. When the air intake valve 153 is opened while the inside of the gas storage tank 152 is pressurized and the inside of the chamber 6 is reduced, ozone gas flows from the gas storage tank 152 into the chamber 6 in one go, and the ozone gas can be supplied into the chamber 6 instantaneously.

[0087] In this embodiment, the timing for opening the air intake valve 153 is set to a period from when the flash lamps FL are turned on and flash light irradiation begins until the surface temperature of the semiconductor wafer W reaches the peak temperature (processing temperature T2). Furthermore, the timing for closing the air intake valve 153 is set to a period after the surface temperature of the semiconductor wafer W reaches the peak temperature, but within one second of the air intake valve 153 being opened. Therefore, ozone is supplied only in the peak temperature region just before and after the surface temperature of the semiconductor wafer W reaches the peak temperature during flash light irradiation. As a result, ozone is supplied only for a short period of time, within one second, including the moment when the surface temperature of the semiconductor wafer W is at its highest, and the oxidation reaction proceeds, allowing a high-quality, thin silicon oxide film to be formed.

[0088] 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 of the present invention. For example, in the above embodiment, the air intake valve 153 is opened during the period from the start of flash light irradiation to the time when the surface temperature of the semiconductor wafer W reaches the peak temperature, but this is not limited to this. It is sufficient that the air intake valve 153 is open at least when the surface temperature of the semiconductor wafer W reaches the peak temperature, and for example, the air intake valve 153 may be opened immediately before the start of flash light irradiation.

[0089] In the above embodiment, air intake valve 153 is closed within one second after it is opened, but it is preferable that this interval be as short as possible, ideally from several tens of milliseconds to about 100 milliseconds. However, considering the drive time of air intake valve 153, at least 400 milliseconds or more is required from the time air intake valve 153 is opened until it is closed.

[0090] Furthermore, in the above embodiment, ozone is stored in the gas storage tank 152 and supplied to the chamber 6, but this is not limiting, and oxygen (O2), ammonia (NH3), nitrogen (N2), or argon (Ar) may be supplied to the chamber 6 in the same manner as in the above embodiment. That is, the process gas stored in the gas storage tank 152 and supplied to the chamber 6 may be any one selected from the group consisting of oxygen, ozone, ammonia, nitrogen, and argon.

[0091] 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.

[0092] Furthermore, in the above embodiment, the semiconductor wafer W is preheated 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 preheating may be performed using a discharge arc lamp (e.g., a xenon arc lamp) or an LED lamp as a continuously lit lamp instead of the halogen lamp HL. [Explanation of symbols]

[0093] 1. Heat treatment equipment 3. Control Unit 4 Halogen heating section 5 Flash heating section 6 chambers 7 Holding part 10 Transfer mechanism 30 shower plate 61 Chamber side 65 Heat Treatment Space 74 Susceptor 81 Gas supply port 83 Gas supply pipe 88 Gas Exhaust Pipe 90 Gas Ring 150 Gas supply unit 151 Ozone Generator 152 Gas storage tank 153 Air intake valve 154 Exhaust valve 155 Exhaust piping 190 Exhaust section 193 Vacuum Pump FL flash lamp HL halogen lamp W Semiconductor wafer

Claims

1. A heat treatment apparatus for heating a substrate by irradiating the substrate with flash light, a chamber for housing the substrate; a flash lamp that irradiates a surface of the substrate accommodated in the chamber with flash light to raise the temperature of the surface of the substrate to a predetermined processing temperature; a gas supply unit that supplies a processing gas into the chamber; an exhaust unit that exhausts gas from the chamber to reduce the pressure inside the chamber; a control unit that controls the gas supply unit and the exhaust unit; Equipped with the gas supply unit includes a gas storage unit that stores a processing gas and an air intake valve provided in a pipe that connects the gas storage unit to the chamber; a heat treatment apparatus in which the control unit controls the gas supply unit so that the air intake valve opens at a predetermined timing while the pressure inside the gas storage unit is set to be higher than atmospheric pressure and the pressure inside the chamber is reduced to be lower than atmospheric pressure.

2. 2. The heat treatment apparatus according to claim 1, The control unit controls the gas supply unit so that the air supply valve opens during the period from when the flash lamp is turned on and flash light irradiation is started until the surface of the substrate reaches the processing temperature.

3. 3. The heat treatment apparatus according to claim 2, The control unit controls the gas supply unit so that the air intake valve closes within one second after the air intake valve opens.

4. 2. The heat treatment apparatus according to claim 1, the gas supply unit further includes an exhaust valve provided in an exhaust pipe extending from the gas storage unit; The heat treatment apparatus maintains the pressure inside the gas storage unit higher than atmospheric pressure by the exhaust valve.

5. 5. The heat treatment apparatus according to claim 1, The heat treatment apparatus, wherein the treatment gas is one gas selected from the group consisting of oxygen, ozone, ammonia, nitrogen, and argon.

6. A heat treatment method for heating a substrate by irradiating the substrate with flash light, comprising: a housing step of housing the substrate in the chamber; an irradiation step of irradiating a surface of the substrate accommodated in the chamber with flash light from a flash lamp to heat the surface of the substrate to a predetermined processing temperature; an exhaust step of exhausting gas from the chamber to reduce the pressure inside the chamber to a pressure lower than atmospheric pressure; a storage step of storing the treatment gas in a gas storage unit and maintaining a pressure in the gas storage unit higher than atmospheric pressure; Equipped with a heat treatment method in which, while the pressure inside the gas storage unit is set to a pressure higher than atmospheric pressure and the pressure inside the chamber is reduced to a pressure lower than atmospheric pressure, an air intake valve provided in a pipe connecting the gas storage unit and the chamber is opened at a predetermined timing.

7. The heat treatment method according to claim 6, a heat treatment method in which the air supply valve is opened during a period from when the flash lamp is turned on and flash light irradiation is started until the surface of the substrate reaches the treatment temperature;

8. The heat treatment method according to claim 7, The heat treatment method includes closing the air intake valve within one second after the air intake valve is opened.

9. The heat treatment method according to claim 6, The heat treatment method further comprises maintaining the inside of the gas storage unit at a pressure higher than atmospheric pressure by an exhaust valve provided in an exhaust pipe extending from the gas storage unit.

10. The heat treatment method according to any one of claims 6 to 9, The heat treatment method, wherein the processing gas is one gas selected from the group consisting of oxygen, ozone, ammonia, nitrogen, and argon.

Images