Heat treatment device and heat treatment method

Abstract

When oxygen gas is supplied during heat treatment of a semiconductor wafer, a plurality of guide plates discharge the oxygen gas such that the discharge directions of a plurality of gas streams are offset in the same direction from a central axis that passes vertically through the center of a chamber. In a storage space between a shower plate and an upper chamber window, a swirling flow of the oxygen gas is formed to agitate the atmosphere in the storage space, thereby making the oxygen concentration in the storage space uniform. When the oxygen gas is ejected from the storage space with a uniform oxygen concentration towards the semiconductor wafer through a plurality of ejection holes in the shower plate, the oxygen concentration in the ejected gas streams also becomes uniform, and the oxygen gas can be supplied with a uniform concentration distribution onto the semiconductor wafer.

Description

Heat treatment apparatus and heat treatment method

[0001] The present invention relates to a heat treatment apparatus and a heat treatment method for performing heat treatment on a substrate by irradiating the substrate with light while supplying a treatment gas such as oxygen to the substrate. Substrates to be treated include, for example, semiconductor wafers, substrates for liquid crystal displays, substrates for flat panel displays (FPDs), substrates for optical disks, substrates for magnetic disks, and substrates for solar cells.

[0002] Flash lamp annealing (FLA), which heats semiconductor wafers in an extremely short time, has been attracting attention in the semiconductor device manufacturing process. Flash lamp annealing is a heat treatment technique that uses a xenon flash lamp (hereinafter, simply referred to as "flash lamp" means a xenon flash lamp) to irradiate the surface of a semiconductor wafer with flash light, thereby raising the temperature of only the surface of the semiconductor wafer in an extremely short time (several 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] Flash lamp annealing is also applied to heat treatment in which a semiconductor wafer is irradiated with flash light while a reactive gas such as oxygen or ammonia is supplied to the wafer. Patent Document 1 discloses a technique for forming an oxide film on the surface of a semiconductor wafer by supplying oxygen into a chamber that contains the semiconductor wafer and irradiating the wafer with flash light.

[0006] When supplying a process gas such as oxygen into a chamber, it is preferable to supply the gas at as uniform a concentration as possible to the semiconductor wafer. For this reason, Patent Document 2 discloses a technique in which a shower plate having a plurality of discharge holes is provided at the top of the chamber, and the process gas is uniformly discharged from the shower plate to spray the process gas evenly over the entire surface of the semiconductor wafer.

[0007] JP 2020-145366 A JP 2012-104808 A

[0008] However, even if the processing gas is supplied through a shower plate, the uniformity of the concentration distribution on the surface of the semiconductor wafer does not fully satisfy the required level, and therefore, further improvement in the uniformity of the concentration distribution on the surface of the semiconductor wafer is required.

[0009] 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 supply a process gas with a uniform concentration distribution onto a substrate.

[0010] In order to solve the above problems, a first aspect of the present invention is a heat treatment apparatus for performing heat treatment by irradiating light onto a substrate while supplying a process gas to the substrate, the heat treatment apparatus comprising: a chamber for accommodating a substrate; a holder for holding the substrate within the chamber; a light irradiation unit for irradiating light onto the substrate held by the holder to heat the substrate; a quartz window provided in the chamber and allowing light irradiated from the light irradiation unit to pass into the chamber; a gas supply unit for supplying process gas into the chamber; a perforated plate provided in the chamber between the holder and the quartz window and having a plurality of ejection holes formed therein for ejecting the process gas supplied from the gas supply unit toward the holder; and a rectification mechanism for directing the process gas supplied from the gas supply unit into a space between the perforated plate and the quartz window as a plurality of gas streams, and rectifying the plurality of gas streams so that the ejection directions of the plurality of gas streams are biased in the same direction from a central axis that passes vertically through the center of the chamber.

[0011] In addition, in a second aspect, in the heat treatment apparatus according to the first aspect, the ejection direction of each of the plurality of gas streams is inclined by 30° or more and 80° or less with respect to a straight line connecting the center of the chamber and the ejection position of the gas stream.

[0012] In a third aspect, in the heat treatment apparatus according to the second aspect, the angles of the ejection directions of the plurality of gas streams with respect to the straight line are constant.

[0013] In a fourth aspect, in the heat treatment apparatus according to the second aspect, angles of the ejection directions of the plurality of gas streams with respect to the straight line are not fixed.

[0014] In addition, a fifth aspect is a heat treatment apparatus according to any one of the first to fourth aspects, wherein the straightening mechanism straightens the multiple gas flows to form a swirling flow in the space between the perforated plate and the quartz window.

[0015] In addition, a sixth aspect is a heat treatment apparatus according to any one of the first to fifth aspects, wherein the straightening mechanism includes a plurality of guide plates arranged in a ring shape to surround the space between the perforated plate and the quartz window, and the processing gas is discharged from the gaps between adjacent guide plates.

[0016] In a seventh aspect, in the heat treatment apparatus according to the sixth aspect, the distance between the adjacent guide plates is 5 mm or more and 10 mm or less.

[0017] In addition, an eighth aspect is a heat treatment apparatus according to the sixth or seventh aspect, wherein the plurality of guide plates are arranged outside the optical path of light traveling from the light irradiation unit toward the substrate held by the holding unit.

[0018] In addition, a ninth aspect is a heat treatment apparatus according to any one of the sixth to eighth aspects, further comprising an angle adjustment mechanism that changes the installation angle of the plurality of guide plates to adjust the ejection directions of the plurality of gas flows.

[0019] In addition, in a tenth aspect, in the heat treatment apparatus according to any one of the first to ninth aspects, the light irradiation unit includes a flash lamp provided on one side of the chamber for irradiating the substrate with flash light, and a continuously lit lamp provided on the other side of the chamber for irradiating the substrate with light to preheat the substrate before irradiating the substrate with flash light.

[0020] In an eleventh aspect, in the heat treatment apparatus according to the tenth aspect, the processing gas is oxygen, and after preheating of the substrate is started by irradiating light from the continuously lit lamp, and before irradiating flash light from the flash lamp, oxygen is introduced from the rectification mechanism into the space between the perforated plate and the quartz window.

[0021] In addition, a twelfth aspect is a heat treatment method for performing heat treatment by irradiating a substrate with light while supplying a process gas to the substrate, the method comprising: a gas supply step of supplying a process gas to a substrate held by a holder in a chamber provided with a quartz window; and a light irradiation step of irradiating the substrate held by the holder with light from a light irradiation unit to heat the substrate, wherein in the gas supply step, the process gas is ejected toward the holder from a plurality of ejection holes formed in a perforated plate provided between the holder and the quartz window, and the process gas is introduced into the space between the perforated plate and the quartz window as a plurality of gas streams, and the plurality of gas streams are rectified so that the ejection directions of the plurality of gas streams are biased in the same direction from a central axis that passes vertically through the center of the chamber.

[0022] In a thirteenth aspect, in the heat treatment method according to the twelfth aspect, the ejection direction of each of the plurality of gas streams is inclined at an angle of 30° or more and 80° or less with respect to a line connecting the center of the chamber and the ejection position of the gas stream.

[0023] A fourteenth aspect is the heat treatment method according to the thirteenth aspect, wherein the angles of the ejection directions of the plurality of gas streams with respect to the straight line are constant.

[0024] A fifteenth aspect is the heat treatment method according to the thirteenth aspect, wherein the angles of the ejection directions of the plurality of gas streams with respect to the straight line are not constant.

[0025] In addition, a sixteenth aspect is a heat treatment method according to any one of the twelfth to fifteenth aspects, wherein in the gas supply step, the plurality of gas flows are rectified to form a swirling flow in the space between the perforated plate and the quartz window.

[0026] A seventeenth aspect is the heat treatment method according to any one of the twelfth to sixteenth aspects, further comprising the step of adjusting the ejection directions of the plurality of gas flows.

[0027] In an eighteenth aspect, in the heat treatment method according to any one of the twelfth to seventeenth aspects, the light irradiation step includes a flash light irradiation step of irradiating the substrate with flash light from a flash lamp provided on one side of the chamber, and a preheating step of irradiating the substrate with light from a continuously lit lamp provided on the other side of the chamber to preheat the substrate before the flash light irradiation step.

[0028] In a nineteenth aspect, in the heat treatment method according to the eighteenth aspect, the processing gas is oxygen, and after the preheating step is started and before the flash light irradiation step, oxygen is introduced into the space between the perforated plate and the quartz window.

[0029] According to the heat treatment apparatuses of the first to eleventh aspects, the process gas supplied from the gas supply unit is introduced into the space between the perforated plate and the quartz window as multiple gas flows, and the multiple gas flows are rectified so that the discharge directions of the multiple gas flows are biased in the same direction from the central axis that passes vertically through the center of the chamber. This forms a swirling flow of the process gas in the space, stirring the atmosphere and making the concentration uniform, and the process gas can be supplied onto the substrate with a uniform concentration distribution.

[0030] According to the heat treatment methods of the twelfth to nineteenth aspects, a process gas is ejected toward the holding part from a plurality of ejection holes formed in a perforated plate provided between the holding part and the quartz window, and the process gas is directed into the space between the perforated plate and the quartz window as a plurality of gas flows. The gas flows are rectified so that the ejection directions of the plurality of gas flows are biased in the same direction from the central axis that passes vertically through the center of the chamber. This forms a swirling flow of the process gas in the space, agitates the atmosphere, and makes the concentration uniform, making it possible to supply the process gas with a uniform concentration distribution onto the substrate.

[0031] FIG. 1 is a vertical cross-sectional view showing the configuration of a heat treatment apparatus according to the present invention. FIG. 2 is a perspective view showing the overall appearance of a holding unit. FIG. 3 is a plan view of a susceptor. FIG. 4 is a cross-sectional view of the susceptor. FIG. 5 is a plan view of a transfer mechanism. FIG. 6 is a side view of the transfer mechanism. FIG. 7 is a plan view showing the arrangement of multiple halogen lamps. FIG. 8 is an enlarged view of the vicinity of a gas ring, a shower plate, and a guide plate. FIG. 9 is a plan view of the arrangement of multiple guide plates and the shower plate as seen from above. FIG. 10 is a partially enlarged view of the arrangement of multiple guide plates. FIG. 11 is a flowchart showing a semiconductor wafer processing procedure. FIG. 12 is a schematic view showing the flow of process gas ejected from gaps between multiple guide plates. FIG. 13 is a view showing process gas ejected from a shower plate when a swirling flow of process gas is formed in a storage space. FIG. 14 is a view showing an example of an angle adjustment mechanism for adjusting the installation angle of multiple guide plates.

[0032] 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."

[0033] FIG. 1 is a longitudinal 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 (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.

[0034] 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, within 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, a shower plate 30, and multiple guide plates 35. 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.

[0035] 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 disk-shaped member made of quartz and functions as a quartz window that transmits flash light emitted from the flash heating unit 5 into the chamber 6. The lower chamber window 64, which forms the floor of the chamber 6, is also a disk-shaped member made of quartz and functions as a quartz window that transmits light from the halogen heating unit 4 into the chamber 6.

[0036] 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 a heat treatment space 65.

[0037] By attaching the reflecting ring 69 and the gas ring 90 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 the central portion of the inner wall surface of the chamber side portion 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.

[0038] Furthermore, a transfer opening (furnace port) 66 is formed in the chamber side 61, through which a semiconductor wafer W is loaded and unloaded into and from the chamber 6. The transfer opening 66 can be opened and closed by a gate valve 185. The transfer opening 66 is connected to the outer peripheral surface of the recess 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 recess 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.

[0039] Furthermore, a through-hole 61a is formed in the chamber side portion 61. A radiation thermometer 20 is attached to the portion of the outer wall surface of the chamber side portion 61 where the through-hole 61a is provided. The through-hole 61a is a cylindrical hole for guiding infrared light emitted from the underside of a semiconductor wafer W held on a susceptor 74 (described later) to the radiation thermometer 20. The through-hole 61a is provided at an angle with respect to the horizontal direction so that the axis of the through-hole 61a intersects with the main surface of the semiconductor wafer W held on the susceptor 74. A transparent window 21 made of barium fluoride material that transmits infrared light in a wavelength range that can be measured by the radiation thermometer 20 is attached to the end of the through-hole 61a facing the heat treatment space 65.

[0040] A gas ring 90 attached to the upper part of the inner wall of the chamber 6 is provided 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 processing gas supply source 85. An air supply valve 84 is inserted in the path of the gas supply pipe 83. When the air supply valve 84 is opened, processing gas is supplied from the processing gas supply source 85 to the gas ring 90, and the processing gas that has passed through the flow path inside the gas ring 90 is supplied from the gas supply port 81 to the heat treatment space 65. The processing gas may be, for example, nitrogen (N ２ ), helium (He), argon (Ar), or other inert gas, or oxygen (O ２ ), hydrogen (H ２ ), ammonia (NH ３ ) or a mixed gas of these.

[0041] 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 at a position lower than 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. An exhaust valve 89 is inserted in the path of the gas exhaust pipe 88. When the exhaust 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.

[0042] The exhaust unit 190 includes a vacuum pump. By operating the exhaust unit 190 to exhaust the gas in the heat treatment space 65 without supplying gas from the gas supply port 81, the pressure inside the chamber 6 can be reduced to below atmospheric pressure. In other words, the exhaust unit 190 also functions as a decompression unit. The vacuum pump of the exhaust unit 190 and the gas exhaust pipe 88 are connected by, for example, three bypass lines with different pipe diameters, and the exhaust flow rate and exhaust speed from the chamber 6 can be changed by opening any one of these bypass lines.

[0043] 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.

[0044] 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 made of quartz and are fixed to the base ring 71 by welding.

[0045] 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.

[0046] A guide ring 76 is installed on the peripheral edge of the upper surface of the holding plate 75. The guide ring 76 is an annular member having an inner diameter larger than the diameter of the semiconductor wafer W. For example, 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 machined pin or the like. Alternatively, the holding plate 75 and the guide ring 76 may be machined as an integrated member.

[0047] The area of ​​the upper surface of the holding plate 75 that is inward of the guide ring 76 is a planar holding surface 75a that holds the semiconductor wafer W. A plurality of substrate support pins 77 are 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. For a semiconductor wafer W with a diameter of 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.

[0048] 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, thereby mounting the holding portion 7 to the chamber 6. When the holding portion 7 is mounted in 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 75 a of the holding plate 75 is a horizontal plane.

[0049] The semiconductor wafer W loaded into the chamber 6 is placed and held in a horizontal position on the susceptor 74 of the holder 7 attached to the chamber 6. At this time, the semiconductor wafer W is supported by 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. Because the heights of the twelve substrate support pins 77 (the distances from the upper ends of the substrate support pins 77 to the holding surface 75a of the holding plate 75) are uniform, the twelve substrate support pins 77 can support the semiconductor wafer W in a horizontal position.

[0050] 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.

[0051] 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 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 the transfer mechanism 10, which will be described later, pass to transfer the semiconductor wafer W.

[0052] 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 pair of transfer arms 11 transfer a semiconductor wafer W to the holder 7 and a retracted position (position indicated by a two-dot chain line in FIG. 5 ) where the pair of transfer arms 11 do not overlap the semiconductor wafer W held by the holder 7 in a plan view. The horizontal movement mechanism 13 may be one that rotates each transfer arm 11 using an individual motor, or one that uses a link mechanism to rotate a pair of transfer arms 11 in unison using a single motor.

[0053] 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 them, 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.

[0054] Returning to FIG. 1 , a gas ring 90, a shower plate 30, and multiple guide plates 35 are provided at the upper inside portion of the chamber 6. FIG. 8 is an enlarged view of the gas ring 90, the shower plate 30, and the guide plates 35. The gas ring 90, which is attached to the upper portion of the inner wall surface of the roughly cylindrical chamber 6, has an annular shape. The gas ring 90 is attached so that its center coincides with the center of the chamber 6. That is, the radial and circumferential directions of the gas ring 90 coincide with the radial and circumferential directions of the chamber 6. 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.

[0055] In the structure in which annular upper ring 91 and lower ring 92 are stacked together, a gap exists between the upper ring 91 and lower ring 92, and this gap functions as a flow path 93 for the process gas. The flow path 93 may have a buffer and labyrinth structure that can act as a resistance portion to the gas flow. The end of the flow path 93 facing the inside of chamber 6 serves as a gas supply port 81. The gas supply port 81 is formed in the shape of a slit along the circumferential direction of chamber 6. The other end of the flow path 93 is connected to a gas supply pipe 83.

[0056] The shower plate 30 is a disk-shaped member made of quartz. Thus, 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 is provided with a plurality of (e.g., approximately 50) jet holes 31 that penetrate vertically. The region in which the jet holes 31 are provided is, for example, a circular region with a diameter of 200 mm. The diameter of each jet hole 31 is, for example, approximately 5 mm to 15 mm. The diameter of the jet holes 31 is not limited to being uniform; for example, the diameter may gradually decrease from the center of the shower plate 30 toward the periphery.

[0057] 8 , the disk-shaped shower plate 30 is mounted in the chamber 6 with its peripheral edge supported by the inner wall surface of the lower ring 92 of the gas ring 90. Therefore, the shower plate 30 is provided above the holder 7 in the chamber 6, between the holder 7 and the upper chamber window 63. When the shower plate 30 is mounted in the chamber 6, a storage space 95 is formed between the upper chamber window 63 and the shower plate 30.

[0058] The process gas supplied from the process gas supply source 85 to the gas ring 90 via the gas supply pipe 83 passes through a flow path 93 in the gas ring 90 and is supplied from the gas supply port 81 to a storage space 95 formed between the upper chamber window 63 and the shower plate 30. The process gas supplied to the storage space 95 is ejected downward from a plurality of ejection holes 31 formed 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.

[0059] Furthermore, at the gas supply port 81, a plurality of guide plates 35 are erected on the upper end surface of the lower ring 92. FIG. 9 is a plan view of the arrangement of the plurality of guide plates 35 and the shower plate 30 as viewed from above. FIG. 10 is a partially enlarged view of the arrangement of the plurality of guide plates 35. The plurality of guide plates 35 (e.g., approximately 200) are arranged in a circular ring shape in a circular region formed by the upper end surface of the lower ring 92. The diameter of the circumference of the circle on which the plurality of guide plates 35 are arranged is larger than the diameter of the semiconductor wafer W, and is φ350 mm to φ400 mm if the diameter of the semiconductor wafer W is φ300 mm. The plurality of guide plates 35 are arranged in a circular ring shape to surround the storage space 95 formed between the shower plate 30 and the upper chamber window 63. Furthermore, the multiple guide plates 35 are arranged on the upper surface of the inner end of the lower ring 92 in a circular area larger than the diameter of the semiconductor wafer W, and are therefore installed outside the optical path of light traveling from the flash heating section 5 to the semiconductor wafer W held in the holding section 7.

[0060] Each guide plate 35 is a rectangular parallelepiped plate-like member. The guide plates 35 are formed from a metal material (e.g., stainless steel) that has excellent strength and heat resistance. As shown in Figures 9 and 10, each of the multiple guide plates 35 is provided at an angle relative to the radial direction of the chamber 6. The multiple guide plates 35 are also provided at intervals without contacting each other. The gap d formed between two adjacent guide plates 35 is 5 mm or more and 10 mm or less.

[0061] The process gas flowing through the flow passages 93 of the gas ring 90 toward the gas supply port 81 is discharged toward the storage space 95 through the gaps between adjacent guide plates 35 included in the plurality of guide plates 35. That is, the plurality of guide plates 35 guide the process gas supplied from the process gas supply source 85 through the flow passages 93 of the gas ring 90 as multiple gas flows into the storage space 95 between the shower plate 30 and the upper chamber window 63. Here, since each of the plurality of guide plates 35 is inclined with respect to the radial direction of the chamber 6, the discharge directions of the multiple gas flows are also inclined obliquely. Specifically, the plurality of guide plates 35 rectify the multiple gas flows so that the discharge directions of the multiple gas flows are biased in the same direction from the central axis CA that vertically passes through the center of the chamber 6.

[0062] When the angle formed between the longitudinal direction of each guide plate 35 and the radial direction of the chamber 6 (the direction of a straight line connecting the central axis CA of the chamber 6 and the guide plate 35) is defined as the installation angle α of the guide plate 35, the installation angle α is 30° or more and 80° or less. The ejection directions of the multiple gas streams are inclined according to the installation angle α of the multiple guide plates 35. In other words, the ejection direction of each of the multiple gas streams is inclined by 30° or more and 80° or less with respect to the straight line connecting the central axis CA of the chamber 6 and the ejection position of the gas stream.

[0063] In this embodiment, the installation angles α of the multiple guide plates 35 are the same, and therefore the angles of the ejection directions of the multiple gas flows relative to the line (the line connecting the central axis CA of the chamber 6 and the ejection positions of the gas flows) are also constant.

[0064] 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.

[0065] 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. The area in which the multiple flash lamps FL are arranged is larger than the planar size of the semiconductor wafer W.

[0066] A xenon flash lamp FL comprises a cylindrical glass tube (discharge tube) filled with xenon gas and having an anode and a 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 to break down the insulation, 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 an extremely short light pulse of 0.1 to 100 milliseconds, thereby enabling the emission of extremely intense light compared to 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 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.

[0067] The reflector 52 is provided above the multiple flash lamps FL so as to cover them entirely. The basic function of the reflector 52 is to reflect the flash light emitted from the multiple flash lamps FL toward the heat treatment space 65. The reflector 52 is made of an aluminum alloy plate, and its surface (the surface facing the flash lamps FL) is roughened by blasting.

[0068] 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.

[0069] 7 is a plan view showing the arrangement of multiple halogen lamps HL. Forty halogen lamps HL are arranged in two rows, upper and lower. Twenty halogen lamps HL are arranged in the upper row, closer to the holder 7, and another 20 halogen lamps HL are 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. The 20 halogen lamps HL in both the upper and lower rows 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.

[0070] 7, the halogen lamps HL are arranged at a higher density 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 arrangement pitch of the halogen lamps HL is shorter 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.

[0071] 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.

[0072] The halogen lamp HL is a filament-type light source that emits light by passing electricity through a filament disposed inside a glass tube, causing it to incandescent. The glass tube is filled with a gas consisting of an inert gas, such as nitrogen or argon, with a small amount of halogen (iodine, bromine, etc.) added. The introduction of halogen makes it possible to set the filament temperature at a high temperature while suppressing filament breakage. Therefore, compared to ordinary incandescent light bulbs, the halogen lamp HL has the characteristics of a longer lifespan and the ability to continuously emit strong light. In other words, the halogen lamp HL is a continuous-light lamp that emits light continuously for at least one second. Furthermore, because the halogen lamp HL is a rod-shaped lamp, it has a long lifespan. By arranging the halogen lamp HL horizontally, it achieves excellent radiation efficiency toward the semiconductor wafer W above.

[0073] A reflector 43 is also 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.

[0074] 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, causing the processing in the heat treatment apparatus 1 to proceed.

[0075] In addition to the above configuration, the heat treatment apparatus 1 is equipped with various cooling structures to prevent excessive temperature rises 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 dissipates heat by creating a gas flow inside. 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.

[0076] Next, a description will be given of the processing procedure for a semiconductor wafer W in the heat treatment apparatus 1. Fig. 11 is a flowchart showing the processing procedure for a semiconductor wafer W. The semiconductor wafer W to be processed here is a silicon (Si) semiconductor substrate, and in the heat treatment apparatus 1, an oxide film is formed by performing heat treatment by irradiating the semiconductor wafer W with flash light while supplying oxygen as a processing gas to the semiconductor wafer W. The processing procedure for the heat treatment apparatus 1, which will be described below, progresses as a result of the control unit 3 controlling each operating mechanism of the heat treatment apparatus 1.

[0077] First, prior to processing the semiconductor wafer W, the intake valve 84 is opened, and the exhaust valve 89 is also opened to start supplying and exhausting air into the chamber 6. When the intake valve 84 is opened, nitrogen gas is supplied from the process gas supply source 85 to the gas ring 90, and then supplied from the gas supply port 81 to the storage space 95 between the upper chamber window 63 and the shower plate 30. The nitrogen gas is ejected downward from the multiple ejection holes 31 provided in the shower plate 30. When the exhaust valve 89 is opened, the gas inside the chamber 6 is exhausted from the gas exhaust holes 86. As a result, the nitrogen gas ejected from the shower plate 30 flows downward, forming a downflow in the heat treatment space 65.

[0078] Subsequently, the gate valve 185 is opened to open the transfer opening 66, and an unprocessed 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 (step S1). At this time, there is a risk that the atmosphere outside the apparatus may be drawn in as the semiconductor wafer W is loaded, but since nitrogen gas is continuously supplied to the chamber 6, the nitrogen gas flows out from the transfer opening 66, and it is possible to minimize the drawing in of such external atmosphere.

[0079] The semiconductor wafer W carried in by the transport 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.

[0080] After the semiconductor wafer W is placed on the lift pins 12, the transfer robot exits the heat treatment space 65, and the transfer opening 66 is closed by the gate valve 185. Then, the pair of transfer arms 11 descend, transferring the semiconductor wafer W from the transfer mechanism 10 to the susceptor 74 of the holder 7, where it is held horizontally from below. The semiconductor wafer W is supported by a plurality of substrate support pins 77 erected on a holding plate 75 and held on the susceptor 74. The semiconductor wafer W is held on the holder 7 with its front surface to be processed facing upward. A predetermined gap is formed between the back surface (the main surface opposite to the front surface) of the semiconductor wafer W supported by the plurality of substrate support pins 77 and the holding surface 75a of the holding plate 75. The pair of transfer arms 11, which have descended to below the susceptor 74, are retracted to a retracted position, i.e., inside the recess 62, by the horizontal movement mechanism 13.

[0081] After the semiconductor wafer W is held horizontally from below by the susceptor 74 of the holder 7, which is made of quartz, the 40 halogen lamps HL of the halogen heating unit 4 are simultaneously turned on to begin preheating (assisted heating) (step S2). Halogen light emitted from the halogen lamps HL passes through the lower chamber window 64 and the susceptor 74, both of which are made of quartz, and is irradiated onto the underside of the semiconductor wafer W. The semiconductor wafer W is preheated by being irradiated with light from the halogen lamps HL, and its temperature rises. Note that the transfer arm 11 of the transfer mechanism 10 is retracted inside the recess 62, so it does not interfere with heating by the halogen lamps HL.

[0082] While the temperature of the semiconductor wafer W is being increased by the light irradiation from the halogen lamps HL, the supply of oxygen gas from the process gas supply source 85 begins (step S3). The oxygen gas supplied from the process gas supply source 85 flows through the flow passages 93 of the gas ring 90 and reaches the plurality of guide plates 35. When the oxygen gas strikes the plurality of guide plates 35, which are inclined relative to the radial direction of the chamber 6, its flow direction is changed and it is discharged through the gaps between the plurality of guide plates 35 toward the storage space 95. In this embodiment, the introduction of oxygen gas into the storage space 95 begins after the start of preheating of the semiconductor wafer W by the light irradiation from the halogen lamps HL and before the irradiation of the flash light from the flash lamps FL. The oxygen gas supplied from the process gas supply source 85 may be mixed with nitrogen gas as a carrier gas.

[0083] 12 is a diagram schematically illustrating the flow of process gas discharged from gaps between the plurality of guide plates 35. The plurality of guide plates 35 are spaced apart without contacting each other, and there is a gap of 5 mm to 10 mm between two adjacent guide plates 35. The oxygen gas supplied from the process gas supply source 85 and reaching the plurality of guide plates 35 is discharged as multiple gas streams from the multiple gaps between the plurality of guide plates 35 toward the storage space 95.

[0084] Furthermore, the multiple guide plates 35 are provided at an angle relative to the radial direction of the chamber 6 so that the ejection directions of the multiple gas streams are biased in the same direction from a central axis CA that passes vertically through the center of the chamber 6. That is, the multiple guide plates 35 are provided at an angle in the same direction relative to the radial direction of the chamber 6. The installation angle α of the multiple guide plates 35 is equal to or greater than 30° and equal to or less than 80°, and the ejection directions of the multiple gas streams are biased from the central axis CA in accordance with the value of the installation angle α.

[0085] 12 , multiple gas streams are discharged from the gaps between the multiple guide plates 35 so that their discharge directions are biased in the same direction from the central axis CA of the chamber 6, thereby forming a swirling flow (vortex flow) of oxygen gas in the storage space 95. This agitates the atmosphere in the storage space 95, and the oxygen concentration in the storage space 95 becomes uniform.

[0086] 13 is a diagram showing the process gas being ejected from the shower plate 30 in a state where a swirling flow of the process gas is formed in the storage space 95. A swirling flow of oxygen gas is formed in the storage space 95 by the multiple guide plates 35, and a portion of the oxygen gas forming the swirling flow is ejected from the multiple ejection holes 31 of the shower plate 30 toward the semiconductor wafer W below. Since the swirling flow makes the oxygen concentration in the storage space 95 uniform, the oxygen concentration of the gas flow ejected from the multiple ejection holes 31 of the shower plate 30 is also uniform. As a result, the oxygen concentration distribution on the top surface of the semiconductor wafer W held on the susceptor 74 is also uniform.

[0087] Furthermore, when preheating is performed by 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.

[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 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.

[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. 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 of the semiconductor wafer W. 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 (step S4). 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.

[0091] The flash light emitted from the flash lamps FL is an extremely short, intense flash of light with an irradiation time of about 0.1 milliseconds to 100 milliseconds, which is produced by converting electrostatic energy previously stored in a capacitor into an extremely short light pulse. The irradiation of such an extremely short, intense flash light causes the surface temperature of the semiconductor wafer W to momentarily rise to a high processing temperature T2 and then rapidly drop. By supplying oxygen gas to the surface of the semiconductor wafer W from the shower plate 30 while irradiating the surface with a flash light to perform flash heating, a silicon oxide film is formed on the surface of the semiconductor wafer W.

[0092] After the flash heating process is completed, the halogen lamps HL are extinguished after a predetermined time has elapsed. This causes the temperature of the semiconductor wafer W to rapidly decrease from the preheating temperature T1. The temperature of the semiconductor wafer W during this decrease is measured by the radiation thermometer 20, and the measurement results are transmitted to the control unit 3. The control unit 3 monitors, based on the measurement results from the radiation thermometer 20, whether the temperature of the semiconductor wafer W has decreased to a predetermined temperature. After the temperature of the semiconductor wafer W has decreased to or below the predetermined temperature, the pair of transfer arms 11 of the transfer mechanism 10 again move horizontally from the retracted position to the transfer operation position and rise, causing the lift pins 12 to protrude from the upper surface of the susceptor 74 and receive the heat-treated semiconductor wafer W from the susceptor 74. Next, the transfer opening 66, which had been closed by the gate valve 185, is opened, and the semiconductor wafer W placed on the lift pins 12 is removed from the chamber 6 by a transfer robot external to the apparatus, completing the heat treatment of the semiconductor wafer W (step S5).

[0093] In this embodiment, when oxygen gas is supplied during heat treatment of the semiconductor wafer W, the oxygen gas is discharged from the plurality of guide plates 35 into the storage space 95 so that the discharge directions of the plurality of gas flows are inclined obliquely. Specifically, the plurality of guide plates 35 discharge the oxygen gas toward the storage space 95 so that the discharge directions of the plurality of gas flows are biased in the same direction from the central axis CA that passes vertically through the center of the chamber 6. As a result, a swirling flow of oxygen gas is formed in the storage space 95 between the shower plate 30 and the upper chamber window 63, which agitates the atmosphere in the storage space 95 and makes the oxygen concentration in the storage space 95 uniform.

[0094] To achieve a uniform oxygen concentration within the storage space 95 through the atmospheric agitation associated with such swirling flows, the installation angle α of the guide plates 35 must be between 30° and 80°. That is, the discharge directions of the gas streams are inclined according to the value of the installation angle α of the guide plates 35. The respective discharge directions of the gas streams must be inclined between 30° and 80° relative to a line connecting the central axis CA of the chamber 6 and the discharge position of the gas stream. If the installation angle α of the guide plates 35 is less than 30°, the discharge directions of the gas streams will generally be directed toward the central axis CA, resulting in no strong swirling flows and little agitation effect. Conversely, if the installation angle α of the guide plates 35 is greater than 80°, the oxygen gas flowing through the flow passage 93 of the gas ring 90 will be blocked by the guide plates 35, making it difficult to form a swirling flow and resulting in no agitation effect. For this reason, the installation angle α of the guide plates 35 is set between 30° and 80°. In order to form the most effective swirling flow and obtain a high stirring effect, it is preferable to set the installation angle α of the multiple guide plates 35 at 60° or more and 70° or less (i.e., to tilt the ejection direction of each of the multiple gas flows at an angle of 60° or more and 70° or less with respect to the line connecting the central axis CA of the chamber 6 and the ejection position of the gas flow).

[0095] Then, oxygen gas is ejected from the storage space 95, in which the oxygen concentration is uniform, toward the semiconductor wafer W through the plurality of ejection holes 31 of the shower plate 30. If the oxygen concentration in the storage space 95 is uniform, the oxygen concentration in the gas flow ejected from the plurality of ejection holes 31 of the shower plate 30 will also be uniform. As a result, oxygen gas can be supplied with a uniform concentration distribution onto the semiconductor wafer W held on the susceptor 74, and it is possible to improve the uniformity of the film thickness of the oxide film formed in the oxide film formation process.

[0096] Although the above describes an embodiment of the present invention, various modifications other than those described above are possible without departing from the spirit and scope of the present invention. For example, in the above embodiment, the installation angles α of all of the multiple guide plates 35 are the same, but guide plates 35 with different installation angles α may be mixed. For example, guide plates 35 with installation angles α of 45° and guide plates 35 with installation angles α of 60° may be mixed. If all of the multiple guide plates 35 have the same installation angle α, the angle of the discharge direction of each of the multiple gas flows relative to a line connecting the central axis CA of the chamber 6 and the respective discharge positions of the multiple gas flows will be constant, and the symmetry of the discharge directions of the multiple gas flows will be high. On the other hand, if guide plates 35 with different installation angles α are mixed, the angle of the discharge direction of each of the multiple gas flows relative to the line will be inconsistent, and the discharge directions of the multiple gas flows will be asymmetric.

[0097] In the above embodiment, oxygen gas is supplied during the heat treatment of the semiconductor wafer W, but this is not limiting. The processing gas to be supplied may be nitrogen (N ２ ), argon (Ar), helium (He), or other inert gas, or hydrogen (H ２ ), ammonia (NH ３ ), oxygen (O ２ ), nitric oxide (NO), nitrous oxide (N ２ O), nitrogen dioxide (NO ２When supplying these process gases, similarly to the above embodiment, the process gas flows are rectified so that the discharge directions of the multiple gas flows are biased in the same direction from the central axis CA of the chamber 6, thereby forming a swirling flow of the process gas in the storage space 95, and the process gas can be supplied onto the semiconductor wafer W with a uniform concentration distribution.

[0098] Furthermore, in the above embodiment, the multiple guide plates 35 are fixed (i.e., the installation angle α is fixed). However, this is not limited thereto. The multiple guide plates 35 may be movable to change the installation angle α. FIG. 14 shows an example of an angle adjustment mechanism for adjusting the installation angle α of the multiple guide plates 35. In the example of FIG. 14, each of the multiple guide plates 35 is installed to be rotatable around a rotation shaft 36. A guide bar 37 is connected to the multiple guide plates 35. By moving the guide bar 37 manually or by a drive mechanism as indicated by arrow AR14, the multiple guide plates 35 can be simultaneously rotated to a predetermined installation angle α. In this way, the installation angle α of the multiple guide plates 35 can be appropriately changed to adjust the discharge direction of the multiple gas streams in any direction. Note that even in this case, the installation angle α of the multiple guide plates 35 needs to be between 30° and 80°.

[0099] Furthermore, in the above embodiment, multiple metal guide plates 35 are provided on the lower ring 92, but instead, multiple transparent guide plates made of, for example, quartz may be arranged in a circular ring shape on the upper surface of the shower plate 30. In this case, the guide plates may be present on the optical path of light traveling from the flash heating unit 5 to the semiconductor wafer W held by the holder 7, but because the guide plates are transparent, they do not interfere with the irradiation of the flash light. Alternatively, multiple transparent guide plates may be attached to the lower surface of the upper chamber window 63.

[0100] Furthermore, in the above embodiment, the discharge directions of the multiple gas streams are biased by the multiple guide plates 35 installed at a predetermined installation angle α. However, instead, for example, the process gas may be discharged from multiple discharge ports tilted from the radial direction of the chamber 6. If the discharge directions of the multiple gas streams discharged from the tilted discharge ports are biased in the same direction from the central axis CA of the chamber 6, a swirling flow of the process gas is formed in the storage space 95, thereby achieving the same effect as the above embodiment. Alternatively, the flow of the process gas may be similarly rectified by multiple grooves tilted from the radial direction of the chamber 6. That is, any configuration may be used as long as a rectifying mechanism is provided that rectifies the multiple gas streams so that the discharge directions of the multiple gas streams are biased in the same direction from the central axis CA that vertically passes through the center of the chamber 6.

[0101] In the above embodiment, the supply of oxygen gas is started after the start of preheating of the semiconductor wafer W by the halogen lamps HL and before the flash light is emitted from the flash lamps FL (i.e., during the preheating process), but the timing of the supply of oxygen gas is arbitrary as long as it is before the flash light is emitted. For example, the supply of oxygen gas may be started before the halogen lamps HL are turned on, or after the semiconductor wafer W has reached the preheating temperature T1.

[0102] 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.

[0103] 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.

[0104] REFERENCE SIGNS LIST 1 Heat treatment apparatus 3 Control unit 4 Halogen heating unit 5 Flash heating unit 6 Chamber 7 Holding unit 10 Transfer mechanism 12 Lift pin 30 Shower plate 31 Jet hole 35 Guide plate 36 Rotation axis 37 Guide bar 61 Chamber side 63 Upper chamber window 65 Heat treatment space 74 Susceptor 81 Gas supply port 84 Air supply valve 85 Processing gas supply source 86 Gas exhaust hole 90 Gas ring 91 Upper ring 92 Lower ring 93 Flow path 95 Storage space CA Central axis FL Flash lamp HL Halogen lamp W Semiconductor wafer

Claims

a quartz window disposed in the chamber and allowing light emitted from the light irradiator to pass into the chamber; a gas supply unit that supplies a processing gas into the chamber; a perforated plate disposed in the chamber between the holder and the quartz window and having a plurality of ejection holes formed therein, for ejecting the processing gas supplied from the gas supply unit toward the holder; and a rectification mechanism that directs the processing gas supplied from the gas supply unit as a plurality of gas streams into a space between the perforated plate and the quartz window, and rectifies the plurality of gas streams so that the ejection directions of the plurality of gas streams are biased in the same direction from a central axis that passes vertically through the center of the chamber.

2. A heat treatment apparatus according to claim 1, wherein the direction of discharge of each of the plurality of gas streams is inclined at an angle of 30° or more and 80° or less with respect to a line connecting the center of the chamber and the discharge position of the gas stream.

3. A heat treatment apparatus according to claim 2, wherein the angles of the ejection directions of the plurality of gas streams relative to the straight line are constant.

4. A heat treatment apparatus according to claim 2, wherein the angles of the ejection directions of the plurality of gas streams relative to the straight line are not fixed.

5. A heat treatment apparatus according to claim 1, wherein said flow straightening mechanism straightens said plurality of gas flows to form a swirling flow in the space between said perforated plate and said quartz window.

6. A heat treatment apparatus according to claim 1, wherein the rectifying mechanism includes a plurality of guide plates arranged in a ring shape so as to surround the space between the perforated plate and the quartz window, and the processing gas is discharged from the gaps between adjacent guide plates.

7. A heat treatment apparatus according to claim 6, wherein the distance between the adjacent guide plates is 5 mm or more and 10 mm or less.

8. A heat treatment apparatus according to claim 6, wherein the plurality of guide plates are disposed outside the optical path of light directed from the light irradiation unit toward the substrate held by the holding unit.

9. A heat treatment apparatus according to claim 6, further comprising an angle adjustment mechanism for adjusting the ejection directions of the plurality of gas streams by changing the installation angles of the plurality of guide plates.

10. A heat treatment apparatus according to claim 1, wherein the light irradiation unit includes: a flash lamp provided on one side of the chamber for irradiating the substrate with a flash of light; and a continuously lit lamp provided on the other side of the chamber for irradiating the substrate with light before irradiating the substrate with the flash of light, thereby preheating the substrate.

11. A heat treatment apparatus according to claim 10, wherein the processing gas is oxygen, and after preheating of the substrate has begun by irradiation of light from the continuously lit lamp, and before flash light is irradiated from the flash lamp, the heat treatment apparatus begins guiding oxygen from the rectification mechanism into the space between the perforated plate and the quartz window.

12. A heat treatment method for performing heat treatment by irradiating a substrate with light while supplying a process gas to the substrate, comprising: a gas supply step of supplying a process gas to a substrate held by a holder in a chamber provided with a quartz window; and a light irradiation step of irradiating the substrate held by the holder with light from a light irradiation unit to heat the substrate, wherein in the gas supply step, the process gas is ejected toward the holder from a plurality of ejection holes formed in a perforated plate provided between the holder and the quartz window, and the process gas is introduced into the space between the perforated plate and the quartz window as a plurality of gas streams, and the plurality of gas streams are rectified so that the ejection directions of the plurality of gas streams are biased in the same direction from a central axis that passes vertically through the center of the chamber.

13. A heat treatment method according to claim 12, wherein the discharge direction of each of the plurality of gas streams is inclined at an angle of 30° or more and 80° or less with respect to a line connecting the center of the chamber and the discharge position of the gas stream.

14. A heat treatment method according to claim 13, wherein the angles of the ejection directions of the plurality of gas streams relative to the straight line are constant.

15. A heat treatment method according to claim 13, wherein the angles of the ejection directions of the plurality of gas streams relative to the straight line are not constant.

16. A heat treatment method according to claim 12, wherein in the gas supply step, the plurality of gas flows are rectified to form a swirling flow in the space between the perforated plate and the quartz window.

17. A heat treatment method according to claim 12, further comprising the step of adjusting the ejection directions of the plurality of gas flows.

18. A heat treatment method according to claim 12, wherein the light irradiation step includes: a flash light irradiation step of irradiating the substrate with flash light from a flash lamp provided on one side of the chamber; and a preheating step of irradiating the substrate with light from a continuously lit lamp provided on the other side of the chamber to preheat the substrate before the flash light irradiation step.

19. A heat treatment method according to claim 18, wherein the processing gas is oxygen, and the introduction of oxygen into the space between the perforated plate and the quartz window is started after the preheating step is started and before the flash light irradiation step.

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