Heat treatment apparatus and heat treatment method

Abstract

To provide a heat treatment apparatus and a heat treatment method capable of supplying a treatment gas onto a substrate with a uniform concentration distribution.SOLUTION: When heat treatment is performed by irradiating a semiconductor wafer held by a susceptor with light, oxygen gas is ejected from a shower plate toward the semiconductor wafer. The shower plate is provided with a plurality of outer ejection holes in addition to the plurality of inner ejection holes. When the oxygen gas supplied from the gas ring to the storage space formed between the shower plate and the upper chamber window is ejected from the plurality of inner ejection holes, a stagnant portion of the residual atmosphere is formed above the peripheral portion of the semiconductor wafer held by the susceptor, but the oxygen gas is discharged from the plurality of outer ejection holes toward the stagnant portion. Thus, the stagnant portion of the residual atmosphere disappears, and the oxygen gas can be supplied onto the semiconductor wafer with a uniform concentration distribution.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[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. [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] 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 processing 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 with multiple discharge holes is provided at the top of the chamber, and the processing gas is uniformly discharged from these holes to spray the processing gas evenly over the entire surface of the semiconductor wafer. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2020-145366 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-104808 Summary of the Invention [Problem to be solved by the invention]

[0008] However, even when the process gas is supplied through a shower plate, it is difficult to achieve a sufficiently uniform concentration distribution of the process gas on the surface of the semiconductor wafer due to the following reasons: Typically, multiple outlet holes are provided in the center of the shower plate, which makes it easy for gas to stagnate on the sides of the chamber, resulting in a problem that the concentration of the process gas, such as oxygen, is lower at the periphery of the semiconductor wafer than at the center, and the thickness of the oxide film formed at the periphery is also thinner.

[0009] On the other hand, if multiple outlet holes are provided on the entire surface of the shower plate, a large amount of process gas is ejected from the outlet holes on the periphery, while almost no process gas is ejected from the outlet holes in the center. This results in a higher concentration of process gas, such as oxygen, at the periphery of the semiconductor wafer compared to the center. Furthermore, much of the process gas is exhausted to the outside of the chamber without contributing to the process, significantly reducing processing efficiency.

[0010] 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. [Means for solving the problem]

[0011] 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 processing gas to the substrate, the heat treatment apparatus comprising: a chamber for accommodating a substrate; a holding unit for holding the substrate within the chamber; a light irradiation unit for irradiating light onto the substrate held by the holding unit 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 processing gas into the chamber; a perforated plate provided in the chamber between the holding unit and the quartz window and having a plurality of first ejection holes formed therein for ejecting processing gas supplied from the gas supply unit toward the holding unit; and an auxiliary gas ejection mechanism for ejecting processing gas toward a stagnation portion of a residual atmosphere formed when processing gas is ejected from the plurality of first ejection holes of the perforated plate.

[0012] In a second aspect, in the heat treatment apparatus according to the first aspect, the plurality of first ejection holes are formed within a first circular area formed by projecting onto the perforated plate a circle having a diameter two-thirds of the diameter of the substrate held by the holding portion, and the auxiliary gas ejection mechanism includes a plurality of second ejection holes provided outside a second circular area formed by projecting onto the perforated plate the substrate held by the holding portion, and the opening rate within the first circular area is higher than the opening rate in a circular ring-shaped area outside the first circular area and inside the second circular area.

[0013] In addition, a third aspect is the heat treatment device according to the second aspect, wherein no ejection holes are present in the annular region.

[0014] In addition, a fourth aspect is a heat treatment apparatus according to the first aspect, wherein the plurality of first ejection holes are formed within a first circular area obtained by projecting onto the perforated plate a circle having a diameter two-thirds of the diameter of the substrate held by the holding part, and the auxiliary gas ejection mechanism includes an ejection port at a height position between the holding part and the perforated plate, which ejects processing gas into a space outside the substrate held by the holding part.

[0015] In addition, a fifth aspect is the heat treatment apparatus according to the fourth aspect, wherein the discharge port is provided in a side wall of the chamber.

[0016] In addition, a sixth aspect is a heat treatment apparatus according to the first aspect, wherein the plurality of first ejection holes are formed within a first circular area formed by projecting onto the perforated plate a circle having a diameter two-thirds of the diameter of the substrate held by the holding portion, and further comprising an intake section at a height position between the holding portion and the perforated plate that sucks in the atmosphere of the space outside the substrate held by the holding portion.

[0017] In addition, in a seventh aspect, in the heat treatment apparatus according to any one of the first to sixth 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.

[0018] In addition, in an eighth aspect, in the heat treatment apparatus according to the seventh 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 started to be discharged from the perforated plate and the auxiliary gas discharge mechanism.

[0019] In addition, a ninth 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 step to heat the substrate, wherein the gas supply step further comprises an auxiliary gas ejection step of ejecting the process gas toward the holder from a plurality of first ejection holes formed in a perforated plate provided between the holder and the quartz window, and ejecting the process gas toward a stagnation portion of a residual atmosphere formed when the process gas is ejected from the plurality of first ejection holes in the perforated plate.

[0020] In a tenth aspect, in the heat treatment method according to the ninth aspect, the plurality of first ejection holes are formed within a first circular area formed by projecting onto the perforated plate a circle having a diameter two-thirds of the diameter of the substrate held by the holding portion, and in the auxiliary gas ejection process, processing gas is ejected from a plurality of second ejection holes provided outside a second circular area formed by projecting onto the perforated plate the substrate held by the holding portion, and the opening rate within the first circular area is higher than the opening rate in a circular ring-shaped area outside the first circular area and inside the second circular area.

[0021] In an eleventh aspect, in the heat treatment method according to the tenth aspect, no processing gas is discharged from the annular region.

[0022] In addition, a twelfth aspect is a heat treatment method according to the ninth aspect, wherein the plurality of first ejection holes are formed within a first circular area obtained by projecting onto the perforated plate a circle having a diameter two-thirds of the diameter of the substrate held by the holding part, and in the auxiliary gas ejection process, processing gas is ejected from an ejection port into a space at a height position between the holding part and the perforated plate and outside the substrate held by the holding part.

[0023] In a thirteenth aspect, in the heat treatment method according to the twelfth aspect, the process gas is discharged from the discharge port provided in the sidewall of the chamber.

[0024] In addition, a 14th aspect is a heat treatment method according to the 9th aspect, wherein the plurality of first ejection holes are formed within a first circular area obtained by projecting onto the perforated plate a circle having a diameter two-thirds of the diameter of the substrate held by the holding part, and further comprising a suction step of suctioning the atmosphere in a space at a height position between the holding part and the perforated plate and outside the substrate held by the holding part.

[0025] In addition, a 15th aspect is a heat treatment method according to any one of the 9th to 14th aspects, 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.

[0026] In addition, a 16th aspect is a heat treatment method according to the 15th aspect, wherein the processing gas is oxygen, and the gas supply process and the auxiliary gas discharge process are started after the preheating process is started and before the flash light irradiation process. [Effects of the Invention]

[0027] According to the heat treatment apparatuses of the first to eighth aspects, the processing gas is ejected toward the stagnation portion of the residual atmosphere formed when the processing gas is ejected from the multiple first ejection holes of the perforated plate, so that the stagnation portion of the residual atmosphere disappears and the processing gas can be supplied onto the substrate with a uniform concentration distribution.

[0028] According to the heat treatment methods of the ninth to sixteenth aspects, the processing gas is ejected toward the stagnation portion of the residual atmosphere formed when the processing gas is ejected from the multiple first ejection holes of the perforated plate, so that the stagnation portion of the residual atmosphere disappears and the processing gas can be supplied onto the substrate with a uniform concentration distribution. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a vertical cross-sectional view showing the configuration of a heat treatment apparatus according to the present invention. [Figure 2] FIG. 2 is a perspective view showing the overall appearance of the holding portion. [Figure 3] FIG. [Figure 4] FIG. 2 is a cross-sectional view of a susceptor. [Figure 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 2 is a plan view showing the arrangement of a plurality of halogen lamps. [Figure 8] FIG. 2 is a side view of a gas ring and a shower plate. [Figure 9] FIG. 2 is a plan view of a shower plate. [Figure 10] 1 is a flowchart showing a processing procedure for a semiconductor wafer. [Figure 11] 10A and 10B are diagrams schematically showing a phenomenon that occurs when only a plurality of inner jet holes are provided in a shower plate. [Figure 12] 10A and 10B are diagrams schematically showing a phenomenon that occurs when jet holes are provided on the entire surface of a shower plate. [Figure 13] FIG. 3 is a diagram schematically illustrating a flow of a processing gas in a chamber in the first embodiment. [Figure 14] FIG. 10 is a diagram showing a configuration of a main part of a second embodiment. [Figure 15] FIG. 10 is a diagram schematically illustrating a flow of a processing gas in a chamber in the second embodiment. [Figure 16] FIG. 10 is a diagram showing a configuration of a main part of a third embodiment. [Figure 17] FIG. 10 is a diagram schematically illustrating a flow of a processing gas in a chamber in a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Hereinafter, expressions indicating relative or absolute positional relationships (e.g., "in one direction," "along one direction," "parallel," "orthogonal," "center," "concentric," "coaxial," etc.) not only strictly represent the positional relationship but also represent a state of relative angular or distance displacement within a tolerance or a range that provides equivalent functionality, unless otherwise specified. Furthermore, expressions indicating an equal state (e.g., "identical," "equal," "homogeneous," etc.) not only represent a state of strict quantitative equality but also represent a state of difference that provides a tolerance or equivalent functionality, unless otherwise specified. Furthermore, expressions indicating a shape (e.g., "circular," "square," "cylindrical," etc.) not only represent a geometrically strict shape but also represent a shape within a range that provides equivalent functionality, such as irregularities or chamfers, unless otherwise specified. Furthermore, expressions such as "comprise," "comprise," "include," "have," etc., regarding components, are not exclusive expressions that exclude the presence of other components. Furthermore, the expression "at least one of A, B, and C" includes "A only," "B only," "C only," "any two of A, B, and C," and "all of A, B, and C."

[0031] First Embodiment FIG. 1 is a vertical cross-sectional view showing the configuration of a heat treatment apparatus 1 according to the present invention. The heat treatment apparatus 1 in FIG. 1 is a flash lamp annealing apparatus that heats a disk-shaped semiconductor wafer W as a substrate by irradiating the semiconductor wafer W with flash light. The size of the semiconductor wafer W to be treated is not particularly limited, but is, 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.

[0032] 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.

[0033] The chamber 6 is constructed by attaching quartz chamber windows to the top and bottom of a cylindrical chamber side portion 61. The chamber side portion 61 has a roughly cylindrical shape with openings at the top and bottom, with an upper chamber window 63 attached to and closing the upper opening, and a lower chamber window 64 attached to and closing the lower opening. The upper chamber window 63, which forms the ceiling of the chamber 6, is a disc-shaped member made of quartz and functions as a quartz window that transmits the flash light emitted from the flash heating unit 5 into the chamber 6. The lower chamber window 64, which forms the floor of the chamber 6, is also a disc-shaped member made of quartz and functions as a quartz window that transmits the light from the halogen heating unit 4 into the chamber 6.

[0034] 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.

[0035] 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.

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

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

[0038] 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 process 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 process gas supply source 85. An intake valve 84 is inserted in the gas supply pipe 83. When the intake valve 84 is opened, the process gas is supplied from the process gas supply source 85 to the gas ring 90, and the process gas that has passed through the flow path inside the gas ring 90 is supplied to the heat treatment space 65 through the gas supply port 81. The process gas may be, for example, an inert gas such as nitrogen (N), helium (He), or argon (Ar); a reactive gas such as oxygen (O), hydrogen (H), or ammonia (NH); or a mixture of these gases.

[0039] Meanwhile, a gas exhaust hole 86 is formed in the lower part of the inner wall of the chamber 6 to exhaust gas from the heat treatment space 65. The gas exhaust hole 86 is formed at a position lower than the recess 62 (i.e., lower than the semiconductor wafer W held by the holder 7), 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.

[0040] The exhaust unit 190 includes a vacuum pump. By operating the exhaust unit 190 to exhaust gas from 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 of these bypass lines.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] The area of ​​the upper surface of the holding plate 75 that is inside the guide ring 76 is a flat holding surface 75a that holds the semiconductor wafer W. A plurality of substrate support pins 77 are provided on the holding surface 75a of the holding plate 75. In this embodiment, a total of 12 substrate support pins 77 are provided at 30° intervals along a circumference concentric with the outer circumferential circle of the holding surface 75a (the inner circumferential circle of the guide ring 76). The diameter of the circle on which the 12 substrate support pins 77 are arranged (the distance between opposing substrate support pins 77) is smaller than the diameter of the semiconductor wafer W. If the diameter of the semiconductor wafer W is 300 mm, the diameter is 270 mm to 280 mm (270 mm in this embodiment). Each substrate support pin 77 is made of quartz. The plurality of substrate support pins 77 may be provided on the upper surface of the holding plate 75 by welding, or may be machined integrally with the holding plate 75.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] Returning to FIG. 1 , a gas ring 90 and shower plate 30 are provided at the upper inside portion of chamber 6. FIG. 8 is a side view of gas ring 90 and shower plate 30. FIG. 9 is a plan view of shower plate 30. Gas ring 90, which is attached to the upper portion of the inner wall surface of roughly cylindrical chamber 6, has an annular shape. Gas ring 90 is attached so that its central axis coincides with the central axis CA of chamber 6. In other words, the radial and circumferential directions of gas ring 90 coincide with the radial and circumferential directions of chamber 6. Gas ring 90 includes an upper ring 91 and a lower ring 92. Both upper ring 91 and lower ring 92 have an annular shape. The upper ring 91 and lower ring 92 are stacked together to form gas ring 90.

[0053] In the structure in which annular upper ring 91 and lower ring 92 are stacked together, a gap exists between upper ring 91 and lower ring 92, and this gap functions as a flow path 93 for the process gas. Flow path 93 may have a buffer and labyrinth structure that can act as a resistance to the gas flow. The end of flow path 93 facing the inside of chamber 6 becomes gas supply port 81. Gas supply port 81 is formed in the shape of a slit along the circumferential direction of chamber 6. The other end of flow path 93 is connected to gas supply pipe 83.

[0054] 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. As shown in FIG. 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. The shower plate 30 is mounted so that its central axis coincides with the central axis CA of the chamber 6. 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.

[0055] The shower plate 30 of the first embodiment is provided with a plurality of inner jet holes (first jet holes) 31 and a plurality of outer jet holes (second jet holes) 32 that penetrate vertically. The diameter of each of the inner jet holes 31 and outer jet holes 32 is, for example, about 5 mm to 15 mm. The plurality of (for example, 50) inner jet holes 31 are formed inside a first circular region C1 that is obtained by projecting onto the shower plate 30 above a circle having a diameter two-thirds that of the semiconductor wafer W held by the holder 7. If the diameter of the semiconductor wafer W is φ300 mm, the diameter of the first circular region C1 in which the inner jet holes 31 are provided is φ200 mm. The diameter of the plurality of inner jet holes 31 in the first circular region C1 is not limited to being uniform; for example, the diameter may gradually decrease from the center of the shower plate 30 toward the periphery.

[0056] On the other hand, the plurality of (e.g., eight) outer ejection holes 32 are formed immediately outside a second circular region C2 when the semiconductor wafer W held by the holder 7 is projected onto the shower plate 30. If the diameter of the semiconductor wafer W is φ300 mm, the diameter of the second circular region C2 is also φ300 mm. The plurality of (e.g., eight) outer ejection holes 32 are provided at equal intervals (e.g., 45° intervals) along the immediately outside of the outer periphery of the second circular region C2. The number of the plurality of outer ejection holes 32 is not limited to eight and may be, for example, 12 or 4, with the intervals being determined according to the number (30° intervals for 12, 90° intervals for 4).

[0057] 9, in the shower plate 30, no ejection holes are provided in an annular region 39 that is outside the first circular region C1 and inside the outer periphery of the second circular region C2. In other words, the opening ratio in the annular region 39 is zero.

[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 the multiple inner ejection holes 31 and multiple outer ejection holes 32 provided in the shower plate 30 toward the holder 7. The process gas ejected in a shower-like manner from the shower plate 30 forms a downflow of process gas from above to below in the heat treatment space 65.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] The control unit 3 controls the various operating mechanisms provided in the heat treatment device 1. The hardware configuration of the control unit 3 is similar to that of a general computer. That is, the control unit 3 includes a CPU, which is a circuit that performs various arithmetic processing, a ROM, which is a read-only memory that stores basic programs, a RAM, which is a readable and writable memory that stores various information, and a storage unit (e.g., a magnetic disk or SSD) that stores control software, data, and the like. The CPU of the control unit 3 executes a predetermined processing program, causing the processing in the heat treatment device 1 to proceed.

[0070] 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.

[0071] Next, a description will be given of the processing procedure for a semiconductor wafer W in the heat treatment apparatus 1. Fig. 10 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.

[0072] 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 to and from 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 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 inner ejection holes 31 and the multiple outer ejection holes 32 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.

[0073] Subsequently, gate valve 185 is opened to open transfer opening 66, and an unprocessed semiconductor wafer W is loaded into heat treatment space 65 in chamber 6 through transfer opening 66 by a transfer robot outside the apparatus (step S1). At this time, there is a risk that the atmosphere outside the apparatus may be drawn in as the semiconductor wafer W is loaded, but since nitrogen gas is continuously supplied to chamber 6, the nitrogen gas flows out from transfer opening 66, making it possible to minimize the inclusion of such external atmosphere.

[0074] 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.

[0075] 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 the 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.

[0076] After the semiconductor wafer W is held from below in a horizontal position by the susceptor 74 of the holder 7, which is made of quartz, the 40 halogen lamps HL of the halogen heating unit 4 are simultaneously turned on to begin preheating (assisted heating) (step S2). The halogen light emitted from the halogen lamps HL passes through the lower chamber window 64 and the susceptor 74, both of which are made of quartz, and is irradiated onto the underside of the semiconductor wafer W. The semiconductor wafer W is preheated by being irradiated with light from the halogen lamps HL, and its temperature rises. Note that the transfer arm 11 of the transfer mechanism 10 is retracted inside the recess 62, so it does not interfere with heating by the halogen lamps HL.

[0077] While the temperature of the semiconductor wafer W is being increased by light irradiation from the halogen lamps HL, the supply of oxygen gas is started from the process gas supply source 85 (step S3). The oxygen gas delivered from the process gas supply source 85 to the gas ring 90 via the gas supply pipe 83 flows through the flow path 93 of the gas ring 90 and enters the storage space 95 formed between the shower plate 30 and the upper chamber window 63 through the gas supply port 81. In this embodiment, the introduction of oxygen gas into the storage space 95 is started after the start of preheating of the semiconductor wafer W by light irradiation from the halogen lamps HL and before the irradiation of 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.

[0078] The oxygen gas that has flowed into the storage space 95 is ejected downward from the plurality of inner ejection holes 31 and the plurality of outer ejection holes 32 provided in the shower plate 30 toward the semiconductor wafer W. The atmosphere in the chamber 6 is exhausted from the gas exhaust holes 86 below the semiconductor wafer W held on the susceptor 74. Therefore, the oxygen gas ejected from the shower plate 30 flows downward from the gap between the susceptor 74 and the base ring 71. If the shower plate 30 were provided with only the plurality of inner ejection holes 31, the following phenomenon would occur. FIG. 11 is a diagram schematically illustrating the phenomenon that occurs when the shower plate 30 is provided with only the plurality of inner ejection holes 31. When the shower plate 30 is provided with only a plurality of inner jet holes 31 (i.e., when a plurality of outer jet holes 32 is not present), oxygen gas is jetted from the center of the shower plate 30, and the oxygen gas flows around the sides of the susceptor 74, below the susceptor 74, and a gas flow is formed in the chamber 6 that is discharged through the gas exhaust holes 86. As a result, as shown in FIG. 11 , a stagnation portion 125 is formed above the peripheral edge of the semiconductor wafer W held on the susceptor 74, where oxygen gas does not flow and nitrogen remains. As a result, the oxygen concentration is lower in the peripheral edge near the stagnation portion 125 than in the central portion of the semiconductor wafer W, and the oxygen concentration distribution on the upper surface of the semiconductor wafer W becomes non-uniform. Therefore, in the subsequent film formation process, it becomes difficult to form an oxide film with a uniform thickness.

[0079] On the other hand, FIG. 12 is a schematic diagram showing a phenomenon that occurs when nozzle holes are provided on the entire surface of the shower plate 30. When nozzle holes are provided on the entire surface of the shower plate 30, the nozzle holes closer to the gas supply port 81 of the gas ring 90, i.e., the nozzle holes closer to the periphery, tend to eject oxygen gas more easily. In particular, when the distance between the shower plate 30 and the upper chamber window 63 is relatively narrow, oxygen gas is ejected more strongly from the nozzle holes on the periphery, causing a large pressure loss. As a result, almost no oxygen gas reaches the nozzle holes in the center, making it difficult for the oxygen gas to be ejected. As a result, as shown in FIG. 12, a stagnation portion 126 containing residual nitrogen is formed above the center of the semiconductor wafer W held on the susceptor 74. Furthermore, oxygen gas ejected from the periphery of the shower plate 30 flows downward from the side of the susceptor 74 without coming into contact with the semiconductor wafer W. Therefore, in this case as well, not only is the oxygen concentration distribution on the upper surface of the semiconductor wafer W uneven, but a large amount of oxygen gas is wasted.

[0080] FIG. 13 is a diagram illustrating a process gas flow within the chamber 6 in the first embodiment. In the first embodiment, oxygen gas flowing from the gas ring 90 into the storage space 95 is ejected from the multiple inner ejection holes 31 and the multiple outer ejection holes 32 provided in the shower plate 30. As described above, when oxygen gas is ejected from the multiple inner ejection holes 31 of the shower plate 30, a stagnation portion 125 containing residual nitrogen is formed above the peripheral edge of the semiconductor wafer W held on the susceptor 74. In the first embodiment, oxygen gas is ejected from the multiple outer ejection holes 32 toward the stagnation portion 125. This eliminates the stagnation portion 125 of the residual atmosphere, making the oxygen concentration in the space above the entire surface of the semiconductor wafer W held on the susceptor 74 uniform, and oxygen gas can be supplied with a uniform concentration distribution onto the semiconductor wafer W. As a result, the oxygen concentration distribution on the upper surface of the semiconductor wafer W is also uniform.

[0081] In particular, in the first embodiment, no ejection holes are provided in the annular region 39 that is outside the first circular region C1 and inside the outer periphery of the second circular region C2 (FIGS. 8 and 9). Therefore, the oxygen gas that flows from the gas ring 90 into the storage space 95 can reach the multiple inner ejection holes 31, and the oxygen gas is ejected not only from the multiple outer ejection holes 32 but also from the multiple inner ejection holes 31. This allows oxygen gas to be supplied onto the semiconductor wafer W with a more uniform concentration distribution.

[0082] 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.

[0083] 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.

[0084] By performing preheating using the halogen lamps HL in this manner, the temperature of the entire semiconductor wafer W is uniformly raised to the preheating temperature T1. During preheating using the halogen lamps HL, the temperature of the peripheral portion of the semiconductor wafer W, where heat dissipation is more likely, tends to be lower than that of the central portion, but the arrangement density of the halogen lamps HL in the halogen heating unit 4 is higher in the region facing the peripheral portion of the semiconductor wafer W than in the region facing the central portion. As a result, a greater amount of light is irradiated onto the peripheral portion of the semiconductor wafer W, where heat dissipation is more likely, and the in-plane temperature distribution of the semiconductor wafer W during the preheating stage can be made uniform.

[0085] 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.

[0086] The flash light emitted from the flash lamp FL is an extremely short, intense flash of light with an irradiation time of 0.1 to 100 milliseconds, in which electrostatic energy previously stored in a capacitor is converted 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.

[0087] After the flash heating process is completed, the halogen lamps HL are turned off after a predetermined time has elapsed. This causes the temperature of the semiconductor wafer W to rapidly decrease from the preheating temperature T1. The temperature of the semiconductor wafer W during this decrease is measured by the radiation thermometer 20, and the measurement result is transmitted to the control unit 3. The control unit 3 monitors, based on the measurement result from the radiation thermometer 20, whether the temperature of the semiconductor wafer W has decreased to a predetermined temperature. After the temperature of the semiconductor wafer W has decreased to or below the predetermined temperature, the pair of transfer arms 11 of the transfer mechanism 10 again move horizontally from the retracted position to the transfer operation position and rise, causing the lift pins 12 to protrude from the upper surface of the susceptor 74 and receive the heat-treated semiconductor wafer W from the susceptor 74. Next, the transfer opening 66, which had been closed by the gate valve 185, is opened, and the semiconductor wafer W placed on the lift pins 12 is removed from the chamber 6 by a transfer robot external to the apparatus, completing the heat treatment of the semiconductor wafer W (step S5).

[0088] In the first embodiment, the shower plate 30 is provided with a plurality of outer jet holes 32 in addition to a plurality of inner jet holes 31. The plurality of inner jet holes 31 are provided inside a first circular area C1 obtained by projecting a circle having a diameter two-thirds that of the semiconductor wafer W held by the holder 7 onto the shower plate 30 above. On the other hand, the plurality of outer jet holes 32 are provided outside a second circular area C2 obtained by projecting the semiconductor wafer W held by the holder 7 onto the shower plate 30.

[0089] Furthermore, no ejection holes are provided in an annular region 39 that is outside the first circular region C1 and inside the outer periphery of the second circular region C2. Therefore, not all of the oxygen gas that flows into the storage space 95 from the gas ring 90 flows out from the plurality of outer ejection holes 32, but is also supplied to the plurality of inner ejection holes 31. When the oxygen gas supplied from the gas ring 90 is ejected from the plurality of inner ejection holes 31 of the shower plate 30, a stagnation portion 125 of the residual atmosphere is formed above the peripheral portion of the semiconductor wafer W held on the susceptor 74, but oxygen gas is ejected from the plurality of outer ejection holes 32 toward the stagnation portion 125. As a result, the stagnation portion 125 of the residual atmosphere disappears, and oxygen gas can be supplied with a uniform concentration distribution onto the semiconductor wafer W held on the susceptor 74, thereby forming an oxide film of a uniform thickness on the surface of the semiconductor wafer W.

[0090] Second Embodiment Next, a second embodiment of the present invention will be described. Fig. 14 is a diagram showing the main configuration of the second embodiment. In this figure, the same elements as in the first embodiment are given the same reference numerals. In the first embodiment, a plurality of outer ejection holes 32 are provided in the shower plate 30, whereas in the second embodiment, an auxiliary ejection port 181 is provided in the side wall of the chamber 6.

[0091] An annular gas ring 90, which is made up of an upper ring 91 and a lower ring 92 stacked together, is attached to the upper part of the inner wall surface of the generally cylindrical chamber 6. A gas supply port 81 is formed in the gas ring 90. The gas supply port 81 of the gas ring 90 is connected to a process gas supply source 85 via a gas supply pipe 83. An intake valve 84 is provided in the gas supply pipe 83.

[0092] A shower plate 30a is attached to the lower ring 92 of the gas ring 90. The shower plate 30a is provided in the chamber 6 above the holder 7 and between the holder 7 and the upper chamber window 63. When the shower plate 30a is attached to the chamber 6, a storage space 95 is formed between the upper chamber window 63 and the shower plate 30a.

[0093] The shower plate 30a of the second embodiment is provided with a plurality of inner ejection holes 31 but no outer ejection holes. The plurality of inner ejection holes 31 are formed inside a circular area obtained by projecting a circle having a diameter two-thirds the diameter of the semiconductor wafer W held by the holder 7 onto the shower plate 30a above.

[0094] An auxiliary gas supply pipe 183 branches off from a branch point in the path of gas supply pipe 83 between processing gas supply source 85 and gas supply valve 84. The tip of auxiliary gas supply pipe 183 penetrates chamber side part 61 of chamber 6 to form auxiliary discharge port 181. An auxiliary gas supply valve 184 is provided on auxiliary gas supply pipe 183.

[0095] Auxiliary outlet port 181, which is the tip of auxiliary gas supply pipe 183, discharges the process gas into a space at a height position between holder 7 and shower plate 30a and outside semiconductor wafer W held by holder 7. Auxiliary outlet port 181 is also formed in chamber side portion 61, i.e., the side wall of chamber 6. Other than these, the remaining configuration of the second embodiment is the same as that of the first embodiment.

[0096] The processing procedure for a semiconductor wafer W in the second embodiment is generally similar to that in the first embodiment. After an unprocessed semiconductor wafer W is loaded into the chamber 6 and held on the susceptor 74, preheating by the halogen lamps HL begins. While the temperature of the semiconductor wafer W is rising due to light irradiation from the halogen lamps HL, supply of oxygen gas from the processing gas supply source 85 begins. At this time, the intake valve 84 is open, and oxygen gas supplied from the processing gas supply source 85 to the gas ring 90 via the gas supply pipe 83 flows from the gas supply port 81 of the gas ring 90 into a storage space 95 formed between the shower plate 30a and the upper chamber window 63. The oxygen gas flowing into the storage space 95 is ejected downward toward the semiconductor wafer W from a plurality of inner ejection holes 31 provided in the shower plate 30a.

[0097] 15 is a diagram schematically illustrating the flow of processing gas within the chamber 6 in the second embodiment. In the second embodiment, the shower plate 30a is provided with no outer ejection holes and only a plurality of inner ejection holes 31. Therefore, when oxygen gas is ejected from the plurality of inner ejection holes 31, a stagnation portion 125 of the residual atmosphere is formed above the peripheral portion of the semiconductor wafer W held by the susceptor 74.

[0098] In the second embodiment, oxygen gas is discharged from an auxiliary discharge port 181 provided on the side wall of the chamber 6 toward the stagnation portion 125. Specifically, when the auxiliary supply valve 184 is opened, a portion of the oxygen gas supplied from the process gas supply source 85 flows through the auxiliary gas supply pipe 183 and is discharged from the auxiliary discharge port 181 toward the stagnation portion 125 of the residual atmosphere. As a result, as in the first embodiment, the stagnation portion 125 of the residual atmosphere disappears, and oxygen gas can be supplied with a uniform concentration distribution onto the semiconductor wafer W held on the susceptor 74, thereby forming an oxide film with a uniform thickness on the surface of the semiconductor wafer W. Furthermore, in the second embodiment, the auxiliary supply valve 184 is closed when the stagnation portion 125 disappears, thereby minimizing the consumption of oxygen gas.

[0099] <Third embodiment> Next, a third embodiment of the present invention will be described. Fig. 16 is a diagram showing the main configuration of the third embodiment. In this figure, the same elements as in the first embodiment are given the same reference numerals. In the first and second embodiments, the processing gas is discharged toward the stagnation portion 125 of the residual atmosphere, but in the third embodiment, the atmosphere in the stagnation portion 125 is also sucked.

[0100] An annular gas ring 90, which is made up of an upper ring 91 and a lower ring 92 stacked together, is attached to the upper part of the inner wall surface of the generally cylindrical chamber 6. A gas supply port 81 is formed in the gas ring 90. The gas supply port 81 of the gas ring 90 is connected to a process gas supply source 85 via a gas supply pipe 83. An intake valve 84 is provided in the gas supply pipe 83.

[0101] The shower plate 30 is attached to the lower ring 92 of the gas ring 90. The shower plate 30 is provided in the chamber 6 above the holder 7 and between the holder 7 and the upper chamber window 63. When the shower plate 30 is attached to the chamber 6, a storage space 95 is formed between the upper chamber window 63 and the shower plate 30.

[0102] The shower plate 30 of the third embodiment is similar to that of the first embodiment. That is, the shower plate 30 of the third embodiment is provided with a plurality of inner ejection holes 31 and a plurality of outer ejection holes 32. The plurality of inner ejection holes 31 are formed inside a first circular region C1 obtained by projecting a circle having a diameter two-thirds that of the semiconductor wafer W held by the holder 7 onto the shower plate 30 above (FIG. 9). On the other hand, the plurality of outer ejection holes 32 are provided outside a second circular region C2 obtained by projecting the semiconductor wafer W held by the holder 7 onto the shower plate 30. Furthermore, no ejection holes are provided in an annular region 39 that is outside the first circular region C1 and inside the outer periphery of the second circular region C2.

[0103] In the third embodiment, a suction port 281 is formed in the chamber side portion 61, i.e., the side wall of the chamber 6. The suction port 281 is connected to an intake unit 285 having a suction function via a suction pipe 283. A suction valve 284 is provided midway along the suction pipe 283. When the suction valve 284 is opened, the suction port 281 at the tip of the suction pipe 283 sucks in the atmosphere in the space outside the semiconductor wafer W held by the holder 7, at a height position between the holder 7 and the shower plate 30. The remaining configuration of the third embodiment, except for the provision of the suction port 281, is the same as that of the first embodiment.

[0104] The processing procedure for a semiconductor wafer W in the third embodiment is generally similar to that in the first embodiment. After an unprocessed semiconductor wafer W is loaded into the chamber 6 and held on the susceptor 74, preheating by the halogen lamps HL begins. While the temperature of the semiconductor wafer W is rising due to light irradiation from the halogen lamps HL, supply of oxygen gas from the process gas supply source 85 begins. At this time, the intake valve 84 is open, and oxygen gas supplied from the process gas supply source 85 to the gas ring 90 via the gas supply pipe 83 flows from the gas supply port 81 of the gas ring 90 into a storage space 95 formed between the shower plate 30 and the upper chamber window 63. The oxygen gas flowing into the storage space 95 is ejected downward toward the semiconductor wafer W from the multiple inner ejection holes 31 and multiple outer ejection holes 32 provided in the shower plate 30.

[0105] 17 is a diagram schematically illustrating the flow of the processing gas in the chamber 6 in the third embodiment. In the third embodiment, when oxygen gas is ejected from the inner ejection holes 31 of the shower plate 30, a stagnation portion 125 of the residual atmosphere is formed above the peripheral portion of the semiconductor wafer W held on the susceptor 74.

[0106] In the third embodiment, oxygen gas is discharged from the plurality of outer ejection holes 32 toward the stagnation portion 125, and the suction valve 284 is opened to suck the residual atmosphere in the stagnation portion 125 through the suction port 281 provided in the side wall of the chamber 6. That is, oxygen gas is discharged from the plurality of outer ejection holes 32 of the shower plate 30 into the stagnation portion 125 of the residual atmosphere, while the atmosphere is also sucked through the suction port 281 provided in the side wall of the chamber 6. As a result, the atmosphere in the stagnation portion 125 is quickly replaced with an oxygen atmosphere, and the stagnation portion 125 disappears, and oxygen gas can be supplied with a uniform concentration distribution onto the semiconductor wafer W held on the susceptor 74. As a result, an oxide film with a uniform thickness can be formed on the surface of the semiconductor wafer W.

[0107] <Modification> Although the embodiments of the present invention have been described above, various modifications can be made to the present invention without departing from the spirit thereof. For example, in the first embodiment, no ejection holes were provided in the annular region 39, which is located outside the first circular region C1 of the shower plate 30 and inside the outer periphery of the second circular region C2. However, several ejection holes may be provided in the annular region 39. For example, some of the outer ejection holes 32 may be provided immediately inside the outer periphery of the second circular region C2. However, the opening area of ​​the ejection holes per unit area in the first circular region C1 is higher than the opening area of ​​the ejection holes per unit area in the annular region 39. In other words, it is sufficient that the opening ratio of the ejection holes in the first circular region C1 is higher than the opening ratio in the annular region 39.

[0108] Furthermore, in the above-described embodiments, oxygen gas is supplied during the heat treatment of the semiconductor wafer W, but the present invention is not limited to this, and the process gas supplied may be an inert gas such as nitrogen (N2), argon (Ar), or helium (He), or a reactive gas such as hydrogen (H2), ammonia (NH3), oxygen (O2), nitric oxide (NO), nitrous oxide (NO2), or nitrogen dioxide (NO2). When supplying these process gases, similarly to the above-described embodiments, the process gas is discharged toward the stagnation portion 125 of the residual atmosphere, thereby eliminating the stagnation portion 125 and supplying the process gas with a uniform concentration distribution onto the semiconductor wafer W held on the susceptor 74.

[0109] Furthermore, in the second embodiment, the auxiliary outlet 181 is provided in the chamber side part 61, but instead, the auxiliary outlet 181 may be provided, for example, in the lower ring 92 of the gas ring 90. That is, the auxiliary outlet 181 may be provided in the side wall of the chamber 6 including the lower ring 92, so that the processing gas is discharged into a space at a height between the holder 7 and the shower plate 30a and outside the semiconductor wafer W held by the holder 7.

[0110] Furthermore, in the first embodiment, the shower plate 30 is provided with a plurality of outer ejection holes 32, and in the second embodiment, the auxiliary ejection ports 181 are provided on the sidewall of the chamber 6, but instead of these, for example, a dedicated gas nozzle may be provided that ejects the processing gas toward the residual atmosphere stagnation portion 125. In short, it is only necessary to provide a mechanism that ejects the processing gas toward the residual atmosphere stagnation portion 125 that is formed when the processing gas is ejected from the plurality of inner ejection holes 31 of the shower plate 30.

[0111] The first and second embodiments may also be combined. That is, a plurality of outer ejection holes 32 may be provided in the shower plate 30, and an auxiliary outlet port 181 may be provided in the side wall of the chamber 6. Furthermore, in the third embodiment, instead of a plurality of outer ejection holes 32, an auxiliary outlet port 181 may be provided in the side wall of the chamber 6. That is, both the auxiliary outlet port 181 and the suction port 281 may be provided in the side wall of the chamber 6.

[0112] In addition, in each of the above embodiments, 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 supplying 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 start to light up, or the supply of oxygen gas may be started after the semiconductor wafer W reaches the preheating temperature T1.

[0113] Furthermore, in each of the above embodiments, 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.

[0114] Furthermore, in each of the above embodiments, 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]

[0115] 1. Heat treatment equipment 3. Control Unit 4 Halogen heating section 5 Flash heating section 6 chambers 7 Holding part 10 Transfer mechanism 12 lift pins 30,30a shower plate 31 Inner spout hole 32 Outer spout 61 Chamber side 63 Upper chamber window 65 Heat Treatment Space 74 Susceptor 81 Gas supply port 84 Air intake valve 85 Process gas supply source 86 Gas exhaust vent 90 Gas Ring 91 Upper Ring 92 Lower Ring 93 Flow path 95 Storage space 125 Retention part 181 Auxiliary outlet 281 Suction port C1 First circular area C2 Second circular area FL flash lamp HL halogen lamp W Semiconductor wafer

Claims

1. 1. A heat treatment apparatus that performs heat treatment on a substrate by irradiating the substrate with light while supplying a processing gas to the substrate, a chamber for housing the substrate; a holder that holds the substrate in the chamber; a light irradiation unit that irradiates the substrate held by the holder with light to heat the substrate; a quartz window provided in the chamber and allowing the light irradiated from the light irradiating unit to pass into the chamber; a gas supply unit that supplies a processing gas into the chamber; a perforated plate provided in the chamber between the holder and the quartz window, the perforated plate having a plurality of first ejection holes formed therein, through which the processing gas supplied from the gas supply unit is ejected toward the holder; an auxiliary gas ejection mechanism that ejects the processing gas toward a stagnation portion of a residual atmosphere that is formed when the processing gas is ejected from the plurality of first ejection holes of the perforated plate; A heat treatment device comprising:

2. 2. The heat treatment apparatus according to claim 1, the plurality of first ejection holes are formed within a first circular area obtained by projecting onto the perforated plate a circle having a diameter that is two-thirds of the diameter of the substrate held by the holding portion, the auxiliary gas ejection mechanism includes a plurality of second ejection holes provided outside a second circular area obtained by projecting the substrate held by the holder onto the perforated plate, A heat treatment apparatus, wherein an aperture ratio within the first circular region is higher than an aperture ratio in an annular region outside the first circular region and inside the second circular region.

3. 3. The heat treatment apparatus according to claim 2, The heat treatment apparatus has no nozzle holes in the annular region.

4. 2. The heat treatment apparatus according to claim 1, the plurality of first ejection holes are formed within a first circular area obtained by projecting onto the perforated plate a circle having a diameter that is two-thirds of the diameter of the substrate held by the holding portion, The auxiliary gas discharge mechanism includes a discharge port that discharges a process gas into a space at a height between the holder and the perforated plate and outside the substrate held by the holder.

5. 5. The heat treatment apparatus according to claim 4, The heat treatment apparatus is configured such that the discharge port is provided in a side wall of the chamber.

6. 2. The heat treatment apparatus according to claim 1, the plurality of first ejection holes are formed within a first circular area obtained by projecting onto the perforated plate a circle having a diameter that is two-thirds of the diameter of the substrate held by the holding portion, The heat treatment apparatus further comprises an intake section that is located at a height between the holder and the perforated plate and that sucks in an atmosphere in a space outside the substrate held by the holder.

7. 2. The heat treatment apparatus according to claim 1, The light irradiation unit a flash lamp provided on one side of the chamber for irradiating the substrate with a flash of light; a continuously lit lamp provided on the other side of the chamber for preheating the substrate by irradiating the substrate with light before irradiating the substrate with flash light; 12. A heat treatment device comprising:

8. 8. The heat treatment apparatus according to claim 7, the process gas is oxygen; A heat treatment apparatus that starts discharging oxygen from the perforated plate and the auxiliary gas discharge mechanism after starting preheating of the substrate by irradiating light from the continuously lit lamp and before irradiating flash light from the flash lamp.

9. A heat treatment method for performing heat treatment on a substrate by irradiating the substrate with light while supplying a process gas to the substrate, comprising: a gas supply step of supplying a processing gas to the substrate held by a holder in a chamber provided with a quartz window; a light irradiation step of irradiating the substrate held by the holder with light from a light irradiation unit to heat the substrate; Equipped with In the gas supplying step, a processing gas is ejected toward the holding part from a plurality of first ejection holes formed in a perforated plate provided between the holding part and the quartz window, The heat treatment method further includes an auxiliary gas ejection step of ejecting the process gas toward a stagnant portion of a residual atmosphere formed when the process gas is ejected from the plurality of first ejection holes of the perforated plate.

10. The heat treatment method according to claim 9, the plurality of first ejection holes are formed within a first circular area obtained by projecting onto the perforated plate a circle having a diameter that is two-thirds of the diameter of the substrate held by the holding portion, In the auxiliary gas ejection step, the processing gas is ejected from a plurality of second ejection holes provided outside a second circular area of ​​the substrate held by the holder projected onto the perforated plate; A heat treatment method, wherein an opening ratio within the first circular region is higher than an opening ratio in an annular region outside the first circular region and inside the second circular region.

11. The heat treatment method according to claim 10, A heat treatment method in which no processing gas is discharged from the annular region.

12. The heat treatment method according to claim 9, the plurality of first ejection holes are formed within a first circular area obtained by projecting onto the perforated plate a circle having a diameter that is two-thirds of the diameter of the substrate held by the holding portion, In the auxiliary gas discharge step, a processing gas is discharged from a discharge port into a space at a height between the holder and the perforated plate and outside the substrate held by the holder.

13. The heat treatment method according to claim 12, The heat treatment method includes discharging a processing gas from the discharge port provided in the side wall of the chamber.

14. The heat treatment method according to claim 9, the plurality of first ejection holes are formed within a first circular area obtained by projecting onto the perforated plate a circle having a diameter that is two-thirds of the diameter of the substrate held by the holding portion, The heat treatment method further comprises a suction step of suctioning the atmosphere in a space located at a height between the holder and the perforated plate and outside the substrate held by the holder.

15. The heat treatment method according to claim 9, The light irradiation step includes: a flash light irradiation step of irradiating the substrate with a flash light from a flash lamp provided on one side of the chamber; a preheating step of preheating the substrate by irradiating the substrate with light from a continuously lit lamp provided on the other side of the chamber before the flash light irradiation step; A heat treatment method comprising:

16. The heat treatment method according to claim 15, the process gas is oxygen; The heat treatment method includes starting the gas supply step and the auxiliary gas discharge step after starting the preheating step and before the flash light irradiation step.

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