Heat treatment method and heat treatment device

Abstract

The present invention provides a heat treatment method and a heat treatment device capable of forming a thinner oxide film with good properties. A silicon semiconductor wafer W is moved into a chamber 6, and preheating of the semiconductor wafer W is started by light irradiation from a halogen lamp HL in a nitrogen gas atmosphere. When the temperature of the semiconductor wafer W reaches a specific switching temperature in the middle of preheating, oxygen is supplied into the chamber 6 to switch the nitrogen gas atmosphere in the chamber 6 to an oxygen gas atmosphere. Then, the surface of the semiconductor wafer W is heated for a very short time by flash irradiation. When the temperature of the semiconductor wafer W is a relatively low temperature lower than the switching temperature, oxidation is suppressed, and oxidation is performed after the temperature reaches a high temperature. As a result, a thinner oxide film with good properties that is dense and has fewer defects at the interface with the silicon base layer can be formed on the surface of the semiconductor wafer W.

Description

Technical Field

[0001] The present invention relates to a heat treatment method and a heat treatment apparatus for forming an oxide film by irradiating light onto a thin plate-shaped precision electronic substrate (hereinafter referred to as a "substrate") such as a semiconductor wafer to heat the substrate. Background Art

[0002] Conventionally, silicon dioxide (SiO2) obtained by oxidizing silicon (Si) has been widely used as a gate insulating film of a field effect transistor (FET). 2 ) film, but in recent years it is being replaced by a high-k film using a material with a higher dielectric constant than silicon dioxide. Regarding high-k films, in order to solve the problem of increased leakage current as the thinning of gate insulating films progresses, the industry is developing metal gate electrodes using metal as gate electrodes and the resulting new stacking structure.

[0003] Even when a high dielectric constant film is used as a gate insulating film, a silicon dioxide film is formed as an interface layer film (base film) between the silicon base layer and the high dielectric constant film (for example, Patent Document 1). The reason is that when a high dielectric constant film is directly formed on a silicon base layer, the defects of the interface increase and the leakage current increases. By forming a silicon dioxide film between the silicon base layer and the high dielectric constant film, the matching of the interface is improved and the leakage current is reduced. That is, the formation of a silicon oxide film can be said to be one of the important elements in the manufacturing technology of semiconductor devices.

[0004] [Prior Technical Literature]

[0005] [Patent Document]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2017-045982 Summary of the invention

[0007] [Problems to be solved by the invention]

[0008] Typically, the silicon oxide film is formed by a thermal oxidation method, in which silicon is treated at a high temperature in an oxidizing gas atmosphere to form a silicon oxide film having good interface compatibility with silicon.

[0009] However, in the conventional thermal oxidation method, when the silicon wafer is placed in the oxidation furnace, the oxidation reaction of silicon starts at a temperature lower than the required oxidation temperature, so there is a case where a silicon oxide film with sufficiently good properties cannot be obtained. In addition, in the conventional thermal oxidation method, the silicon is thermally oxidized in the furnace for a relatively long time, so it is difficult to control the film thickness of the silicon oxide film at the nanometer level.

[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 method and a heat treatment apparatus capable of forming a thin oxide film having excellent characteristics.

[0011] [Technical means to solve the problem]

[0012] In order to solve the above-mentioned problem, the invention of Technical Solution 1 is a heat treatment method for forming an oxide film by heating a substrate by irradiating light to the substrate, and is characterized in that it comprises: a receiving step of receiving the substrate in a chamber; a heating step of irradiating light to the substrate to heat the substrate; and a gas atmosphere switching step, when the substrate reaches a specific switching temperature in the middle of the heating step, an oxidizing gas is supplied to the chamber to switch the chamber from an inert gas atmosphere to an oxidizing gas atmosphere.

[0013] In addition, the invention of technical solution 2 is a heat treatment method according to the invention of technical solution 1, characterized in that: the heating process includes: a preheating process, irradiating light to the substrate from a continuously lit lamp; and a flash heating process, after the preheating process, irradiating the substrate with a flash from a flash lamp; and in the middle of the preheating process, starting to supply the oxidizing gas into the chamber.

[0014] In addition, the invention of technical solution 3 is a heat treatment method according to the invention of technical solution 2, characterized in that the flash is irradiated when the concentration of the oxidizing gas in the chamber reaches a specific value.

[0015] In addition, the invention of technical solution 4 is a heat treatment method according to the invention of technical solution 2, characterized in that an oxide film is formed on the surface of the substrate by irradiating the substrate with a flash, and impurities injected into the substrate are activated.

[0016] In addition, the invention of technical solution 5 is a heat treatment method according to any one of the inventions of technical solutions 1 to 4, characterized in that: after the heating step is completed, the supply of the oxidizing gas into the chamber is stopped and the pressure in the chamber is reduced.

[0017] In addition, the invention of technical solution 6 is a heat treatment method according to any one of the inventions of technical solutions 1 to 4, characterized in that: after the heating step is completed, the supply of the oxidizing gas into the chamber is stopped, and hydrogen is supplied into the chamber.

[0018] In addition, the invention of technical solution 7 is a heat treatment method according to any one of the inventions of technical solutions 1 to 4, characterized in that: after the heating process is completed, the supply of the oxidizing gas into the chamber is stopped, and argon gas or xenon gas is supplied into the chamber.

[0019] In addition, the invention of Technical Solution 8 is a heat treatment method according to the invention of Technical Solution 1, characterized in that: the substrate is a silicon substrate, and the oxidizing gas is a gas selected from the group consisting of oxygen, ozone, oxygen free radicals and water vapor.

[0020] In addition, the invention of technical solution 9 is a heat treatment method according to the invention of technical solution 8, characterized in that: in the gas atmosphere switching step, an inert gas is mixed with the oxidizing gas and supplied into the chamber.

[0021] In addition, the invention of technical solution 10 is a heat treatment method according to the invention of technical solution 8 or 9, characterized in that the switching temperature is above 400°C.

[0022] In addition, the invention of technical solution 11 is a heat treatment device that heats a substrate by irradiating light to the substrate to form an oxide film, and is characterized in that it comprises: a chamber that accommodates the substrate; a light irradiation unit that irradiates light to the substrate to heat the substrate; a gas supply unit that supplies an oxidizing gas into the chamber; and a control unit that controls the gas supply unit in such a manner that the oxidizing gas is supplied into the chamber to switch the chamber from an inert gas atmosphere to an oxidizing gas atmosphere when the substrate reaches a specific switching temperature in the middle of being heated by light irradiation from the light irradiation unit.

[0023] In addition, the invention of technical solution 12 is a heat treatment device according to the invention of technical solution 11, characterized in that: the light irradiation unit includes: a continuously lit lamp to irradiate light to the substrate to preheat the substrate; and a flash lamp to irradiate a flash of light to the substrate after the preheating; and the control unit controls the gas supply unit in such a manner that the oxidizing gas is supplied into the chamber starting in the middle of the preheating.

[0024] In addition, the invention of technical solution 13 is a heat treatment device according to the invention of technical solution 12, characterized in that the flash lamp irradiates the flash when the concentration of the oxidizing gas in the chamber reaches a specific value.

[0025] In addition, the invention of technical solution 14 is a heat treatment device according to the invention of technical solution 12, characterized in that: a flash is irradiated on the substrate by the flash lamp to form an oxide film on the surface of the substrate, and impurities injected into the substrate are activated.

[0026] In addition, the invention of technical solution 15 is a heat treatment device according to the invention of any one of technical solutions 11 to 14, characterized in that it further includes a decompression section for decompressing the pressure in the chamber, and after the heating of the substrate by light irradiation from the light irradiation section is completed, the gas supply section stops supplying the oxidizing gas into the chamber, and the decompression section decompresses the pressure in the chamber.

[0027] In addition, the invention of technical solution 16 is a heat treatment device according to the invention of any one of technical solutions 11 to 14, characterized in that: after the heating of the substrate by light irradiation from the light irradiation unit is completed, the gas supply unit stops supplying the oxidizing gas into the chamber and supplies hydrogen into the chamber.

[0028] In addition, the invention of technical solution 17 is a heat treatment device according to the invention of any one of technical solutions 11 to 14, characterized in that: after the heating of the substrate by light irradiation from the light irradiation unit is completed, the gas supply unit stops supplying the oxidizing gas into the chamber and supplies argon gas or xenon gas into the chamber.

[0029] In addition, the invention of technical solution 18 is a heat treatment device according to the invention of technical solution 11, characterized in that: the substrate is a silicon substrate, and the oxidizing gas is a gas selected from the group consisting of oxygen, ozone, oxygen free radicals and water vapor.

[0030] In addition, the invention of technical solution 19 is a heat treatment device according to the invention of technical solution 18, characterized in that the gas supply part mixes an inert gas with the oxidizing gas and supplies it into the chamber.

[0031] In addition, the invention of technical solution 20 is a heat treatment device according to the invention of technical solution 18 or 19, characterized in that the switching temperature is above 400°C.

[0032] [Effects of the Invention]

[0033] According to the invention of technical solutions 1 to 10, when the substrate reaches a specific switching temperature in the middle of the heating process, an oxidizing gas is supplied into the chamber to switch the chamber from an inert gas atmosphere to an oxidizing gas atmosphere. Therefore, when the temperature of the substrate is a relatively low temperature lower than the switching temperature, oxidation is suppressed, and oxidation is performed after the temperature becomes a high temperature, thereby being able to form a thinner oxide film with good properties on the substrate.

[0034] In particular, according to the invention of claim 5, after the heating step is completed, the supply of the oxidizing gas into the chamber is stopped and the pressure in the chamber is reduced, so that the growth of the oxide film can be stopped quickly and the film thickness can be appropriately controlled.

[0035] According to the invention of technical solutions 11 to 20, when the substrate reaches a specific switching temperature in the middle of being heated by light irradiation from the light irradiation part, an oxidizing gas is supplied into the chamber to switch the chamber from an inert gas atmosphere to an oxidizing gas atmosphere. Therefore, when the temperature of the substrate is a relatively low temperature lower than the switching temperature, oxidation is suppressed, and oxidation is performed after the temperature becomes a high temperature, thereby being able to form a thinner oxide film with good properties on the substrate.

[0036] In particular, according to the invention of technical solution 15, after the heating of the substrate by light irradiation from the light irradiation unit is completed, the gas supply unit stops supplying the oxidizing gas into the chamber, and the decompression unit reduces the pressure in the chamber, thereby enabling the growth of the oxide film to be quickly stopped and the film thickness to be appropriately controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a longitudinal sectional view showing the structure of the heat treatment apparatus of the present invention.

[0038] Figure 2 It is a perspective view showing the overall appearance of the holding portion.

[0039] Figure 3 This is a top view of the crystal seat.

[0040] Figure 4 It is a cross-sectional view of the crystal seat.

[0041] Figure 5 It is a top view of the transfer mechanism.

[0042] Figure 6 It is a side view of the transfer mechanism.

[0043] Figure 7 It is a top view showing the arrangement of a plurality of halogen lamps.

[0044] Figure 8 This is a flow chart showing the procedure of the heat treatment method of the present invention.

[0045] Fig. 9 This is a diagram showing changes in the surface temperature of a semiconductor wafer.

[0046] Fig.10 It is a graph showing changes in oxygen concentration in the chamber.

[0047] Fig.11 It is a graph showing the pressure change in the chamber. DETAILED DESCRIPTION

[0048] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0049] First, the heat treatment apparatus of the present invention will be described. Figure 1 It is a longitudinal sectional view showing the structure of the heat treatment apparatus 1 of the present invention. Figure 1 The heat treatment device 1 is a flash lamp annealing device that heats a semiconductor wafer W in the shape of a disk as a substrate by flash irradiating the semiconductor wafer W. The size of the semiconductor wafer W to be processed is not particularly limited, and is, for example, φ300 mm or φ450 mm. Figure 1 In the following drawings, the size or quantity of each component may be exaggerated or simplified as necessary to facilitate understanding.

[0050] The heat treatment apparatus 1 includes a chamber 6 for accommodating a semiconductor wafer W, a flash heating unit 5 having a plurality of flash lamps FL built therein, and a halogen heating unit 4 having a plurality of halogen lamps HL built therein. The flash heating unit 5 is provided on the upper side of the chamber 6, and the halogen heating unit 4 is provided on the lower side. The heat treatment apparatus 1 includes a gas supply unit 90 for supplying a processing gas into the chamber 6. In addition, the heat treatment apparatus 1 includes a holding unit 7 for holding the semiconductor wafer W in a horizontal position inside the chamber 6, and a transfer mechanism 10 for transferring the semiconductor wafer W between the holding unit 7 and the outside of the apparatus. Furthermore, the heat treatment apparatus 1 includes a control unit 3 for controlling the halogen heating unit 4, the flash heating unit 5, and various operating mechanisms provided in the chamber 6 to perform heat treatment of the semiconductor wafer W.

[0051] The chamber 6 is formed by installing chamber windows made of quartz on the upper and lower parts of a cylindrical chamber side portion 61. The chamber side portion 61 has a generally cylindrical shape with upper and lower openings, and an upper chamber window 63 is installed at the upper opening to close it, and a lower chamber window 64 is installed at the lower opening to close it. The upper chamber window 63 constituting the ceiling portion of the chamber 6 is a disk-shaped member formed of quartz, and functions as a quartz window that allows the flash emitted from the flash heating unit 5 to pass into the chamber 6. In addition, the lower chamber window 64 constituting the floor portion of the chamber 6 is also a disk-shaped member formed of quartz, and functions as a quartz window that allows the light from the halogen heating unit 4 to pass into the chamber 6.

[0052] In addition, a reflection ring 68 is installed on the upper part of the inner wall of the chamber side portion 61, and a reflection ring 69 is installed on the lower part. The reflection rings 68 and 69 are both formed in a circular ring shape. The upper reflection ring 68 is installed by embedding from the upper side of the chamber side portion 61. On the other hand, the lower reflection ring 69 is installed by embedding from the lower side of the chamber side portion 61 and fixing with screws omitted from the figure. That is, the reflection rings 68 and 69 are both installed in the chamber side portion 61 so as to be freely loaded and unloaded. The inner space of the chamber 6, that is, the space surrounded by the upper chamber window 63, the lower chamber window 64, the chamber side portion 61 and the reflection rings 68 and 69 is defined as a heat treatment space 65.

[0053] By installing the reflection rings 68 and 69 on the chamber side portion 61, a recessed portion 62 is formed on the inner wall surface of the chamber 6. That is, the recessed portion 62 is formed to be surrounded by the central portion of the inner wall surface of the chamber side portion 61 where the reflection rings 68 and 69 are not installed, the lower end surface of the reflection ring 68, and the upper end surface of the reflection ring 69. The recessed portion 62 is formed in a circular ring shape along the horizontal direction on the inner wall surface of the chamber 6, surrounding the holding portion 7 holding the semiconductor wafer W. The chamber side portion 61 and the reflection rings 68 and 69 are formed of a metal material (for example, stainless steel) having excellent strength and heat resistance.

[0054] In addition, a transport opening (furnace opening) 66 is formed on the chamber side portion 61, and the transport opening (furnace opening) 66 is used to carry in and out the semiconductor wafer W relative to the chamber 6. The transport opening 66 can be opened and closed by the gate valve 185. The transport opening 66 is connected to the outer peripheral surface of the recess 62. Therefore, when the gate valve 185 opens the transport opening 66, the semiconductor wafer W can be carried into the heat treatment space 65 through the recess 62 from the transport opening 66 and the semiconductor wafer W can be carried out from the heat treatment space 65. In addition, if the gate valve 185 closes the transport opening 66, the heat treatment space 65 in the chamber 6 becomes a closed space.

[0055] Furthermore, a through hole 61a is formed in the chamber side portion 61. A radiation thermometer 20 is installed at a portion of the outer wall surface of the chamber side portion 61 where the through hole 61a is formed. The through hole 61a is a cylindrical hole for guiding infrared light radiated from the lower surface of the semiconductor wafer W held on the crystal seat 74 described below to the radiation thermometer 20. The through hole 61a is provided obliquely with respect to the horizontal direction in such a manner that the axis of the through direction thereof intersects with the main surface of the semiconductor wafer W held on the crystal seat 74. A transparent window 21 made of a barium fluoride material is provided at the end of the through hole 61a facing the heat treatment space 65 side, through which infrared light of a wavelength range that can be measured by the radiation thermometer 20 is transmitted. The radiation thermometer 20 receives the infrared light radiated from the lower surface of the semiconductor wafer W via the transparent window 21, and measures the temperature of the semiconductor wafer W based on the intensity of the infrared light.

[0056] In addition, a gas supply hole 81 is formed on the upper part of the inner wall of the chamber 6, and the gas supply hole 81 supplies the processing gas to the heat treatment space 65. The gas supply hole 81 is formed and arranged at a position higher than the recessed portion 62, and may also be arranged on the reflection ring 68. The gas supply hole 81 is connected to the supply pipe 83 of the gas supply part 90 via a buffer space 82 formed in a circular ring shape inside the side wall of the chamber 6. The supply pipe 83 is divided into two forks, one of which is connected to the oxygen supply source 93, and the other is connected to the nitrogen supply source 94. A valve 91 is provided in the pipe branched from the supply pipe 83 and connected to the oxygen supply source 93, and a valve 92 is provided in the pipe connected to the nitrogen supply source 94. If the valve 91 is opened, oxygen (O 2 ) to the supply pipe 83. On the other hand, if the valve 92 is opened, nitrogen gas (N 2 ) to the supply pipe 83. If both valves 91 and 92 are opened, a mixed gas of oxygen and nitrogen is delivered to the supply pipe 83. The oxygen supply source 93, the nitrogen supply source 94, the valve 91, the valve 92 and the supply pipe 83 constitute a gas supply unit 90 of the heat treatment device 1. The processing gas delivered from the supply pipe 83 flows into the buffer space 82, flows in a diffused manner in the buffer space 82 where the fluid resistance is smaller than that of the gas supply hole 81, and is supplied from the gas supply hole 81 to the heat treatment space 65. In addition, the supply flow rates of oxygen and nitrogen can be adjusted by using a flow regulating valve (not shown) or the like provided on the branch pipe.

[0057] On the other hand, a gas discharge hole 86 is formed at the lower part of the inner wall of the chamber 6, and the gas discharge hole 86 discharges the gas in the heat treatment space 65. The gas discharge hole 86 is formed at a lower position than the recessed portion 62, and can also be set on the reflection ring 69. The gas discharge hole 86 is connected to the gas discharge pipe 88 via a buffer space 87 formed in an annular shape inside the side wall of the chamber 6. The gas discharge pipe 88 is connected to the exhaust part 190. In addition, a valve 89 is inserted in the middle of the path of the gas discharge pipe 88. If the valve 89 is opened, the gas in the heat treatment space 65 is discharged from the gas discharge hole 86 to the gas discharge pipe 88 via the buffer space 87. In addition, a plurality of gas supply holes 81 and gas discharge holes 86 can be set along the circumferential direction of the chamber 6, and can also be slit-shaped.

[0058] In addition, a gas exhaust pipe 191 for exhausting the gas in the heat treatment space 65 is also connected to the front end of the transfer opening 66. The gas exhaust pipe 191 is connected to the exhaust unit 190 via a valve 192. By opening the valve 192, the gas in the chamber 6 is exhausted through the transfer opening 66.

[0059] The exhaust unit 190 is provided with an exhaust pump. By operating the exhaust unit 190 and opening the valves 89 and 192, the gas atmosphere in the chamber 6 is exhausted from the gas exhaust pipes 88 and 191 to the exhaust unit 190. When the gas atmosphere of the closed space, that is, the heat treatment space 65, is exhausted by the exhaust unit 190 without supplying any gas from the gas supply hole 81, the pressure in the chamber 6 can be reduced to a pressure lower than the atmospheric pressure. That is, the exhaust unit 190 also functions as a decompression unit that decompresses the pressure in the chamber 6.

[0060] Figure 2 : is a perspective view showing the overall appearance of the holding part 7. The holding part 7 is composed of a base ring 71, a connecting part 72 and a crystal seat 74. The base ring 71, the connecting part 72 and the crystal seat 74 are all formed of quartz. That is, the entire holding part 7 is formed of quartz.

[0061] The base ring 71 is a quartz member in an arc shape in which a portion is missing from a circular ring shape. The missing portion is provided to prevent interference between the transfer arm 11 of the transfer mechanism 10 described below and the base ring 71. The base ring 71 is placed on the bottom surface of the recess 62 and is thereby supported on the wall surface of the chamber 6 (see Figure 1 ). On the upper surface of the base ring 71, a plurality of connecting parts 72 (four in this embodiment) are vertically provided along the circumferential direction of the annular shape. The connecting part 72 is also a quartz member and is fixed to the base ring 71 by welding.

[0062] The crystal susceptor 74 is supported by four connecting portions 72 provided on the base ring 71 . Figure 3 74 is a top view of the crystal seat. Figure 4 74. The crystal base 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 plate-shaped member formed 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 larger plane size than the semiconductor wafer W.

[0063] A guide ring 76 is provided on the peripheral portion of the upper surface of the holding plate 75. The guide ring 76 is a member in the shape of a circular ring having an inner diameter larger than the diameter of the semiconductor wafer W. For example, when 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 is formed into a tapered surface that expands upward from the holding plate 75. The guide ring 76 is formed of the same quartz 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 integral member.

[0064] The area on the upper surface of the holding plate 75 that is closer to the inner side than the guide ring 76 is formed as a planar holding surface 75a for holding the semiconductor wafer W. A plurality of substrate support pins 77 are erected on the holding surface 75a of the holding plate 75. In the present embodiment, a total of 12 substrate support pins 77 are erected at intervals of 30° along a circle that is concentric with the outer circumference of the holding surface 75a (the inner circumference of the guide ring 76). The diameter of the circle on which the 12 substrate support pins 77 are arranged (the distance between the opposing substrate support pins 77) is smaller than the diameter of the semiconductor wafer W. If the diameter of the semiconductor wafer W is φ300 mm, the diameter of the circle is φ270 mm to φ280 mm (φ270 mm in the present embodiment). Each substrate support pin 77 is formed of quartz. A plurality of substrate support pins 77 can be arranged on the upper surface of the holding plate 75 by welding, or can be processed into one piece with the holding plate 75.

[0065] Return to Figure 2 , the four connecting parts 72 erected on the base ring 71 and the peripheral part of the holding plate 75 of the crystal seat 74 are fixed by welding. That is, the crystal seat 74 and the base ring 71 are fixedly connected by the connecting parts 72. The base ring 71 of the holding part 7 is supported on the wall surface of the chamber 6, thereby installing the holding part 7 in the chamber 6. When the holding part 7 is installed in the chamber 6, the holding plate 75 of the crystal seat 74 is in a horizontal posture (a posture in which the normal line is consistent with the vertical direction). That is, the holding surface 75a of the holding plate 75 becomes a horizontal plane.

[0066] The semiconductor wafer W carried into the chamber 6 is placed and held in a horizontal posture on the crystal pedestal 74 of the holding portion 7 installed in the chamber 6. At this time, the semiconductor wafer W is supported and held on the crystal pedestal 74 by 12 substrate support pins 77 vertically provided on the holding plate 75. More strictly speaking, the upper ends of the 12 substrate support pins 77 contact the lower surface of the semiconductor wafer W to support the semiconductor wafer W. The heights of the 12 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 semiconductor wafer W can be supported in a horizontal posture by the 12 substrate support pins 77.

[0067] In addition, the semiconductor wafer W is supported at a specific interval from the holding surface 75a of the holding plate 75 by the plurality of substrate supporting pins 77. The thickness of the guide ring 76 is greater than the height of the substrate supporting pins 77. Therefore, the guide ring 76 prevents the horizontal positional deviation of the semiconductor wafer W supported by the plurality of substrate supporting pins 77.

[0068] In addition, if Figure 2 and Figure 3As shown, the holding plate 75 of the crystal base 74 is formed with an opening 78 extending vertically. The opening 78 is provided for the radiation thermometer 20 to receive the radiation light (infrared light) radiated from the lower surface of the semiconductor wafer W. That is, the radiation thermometer 20 receives the light radiated from the lower surface of the semiconductor wafer W through the opening 78 and the transparent window 21 installed in the through hole 61a of the chamber side 61, thereby measuring the temperature of the semiconductor wafer W. Furthermore, the holding plate 75 of the crystal base 74 is provided with four through holes 79, and the four through holes 79 are passed through by the lift pins 12 of the transfer mechanism 10 described below to transfer the semiconductor wafer W.

[0069] Figure 5 1 is a top view of the transfer mechanism 10. Figure 6 1 is a side view of the transfer mechanism 10. The transfer mechanism 10 includes two transfer arms 11. The transfer arms 11 are formed in an arc shape along the substantially annular recess 62. Two lift pins 12 are vertically provided on each transfer arm 11. The transfer arms 11 and the lift pins 12 are formed of quartz. Each transfer arm 11 can be rotated by a horizontal moving mechanism 13. The horizontal moving mechanism 13 enables a pair of transfer arms 11 to be in a transfer operation position ( Figure 5 The solid line position) and the retreat position ( Figure 5 The transfer action position is a position for transferring the semiconductor wafer W relative to the holding portion 7, and the retreat position is a position that does not overlap with the semiconductor wafer W held on the holding portion 7 when viewed from above. The horizontal movement mechanism 13 may be a mechanism that rotates each transfer arm 11 separately using a separate motor, or a mechanism that rotates a pair of transfer arms 11 in conjunction with each other using a link mechanism and a single motor.

[0070] In addition, the pair of transfer arms 11 are moved up and down together with the horizontal moving 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 the through holes 79 (see Figure 2 , 3), the upper end of the lift pin 12 protrudes from the upper surface of the crystal seat 74. On the other hand, when the lifting mechanism 14 causes the pair of transfer arms 11 to descend in the transfer action position and pulls the lift pin 12 out of the through hole 79, and the horizontal moving mechanism 13 causes the pair of transfer arms 11 to move in an open manner, each transfer arm 11 moves to a retreat position. The retreat position of the pair of transfer arms 11 is directly above the base ring 71 of the holding portion 7. The base ring 71 is placed on the bottom surface of the recess 62, so the retreat position of the transfer arm 11 becomes the inner side of the recess 62. In addition, near the location where the drive portion (horizontal moving mechanism 13 and lifting mechanism 14) of the transfer mechanism 10 is provided, an exhaust mechanism (not shown) is also provided, which is configured to exhaust the gas atmosphere around the drive portion of the transfer mechanism 10 to the outside of the chamber 6.

[0071] Return to Figure 1 An oxygen concentration meter 99 is provided in the chamber 6 . The oxygen concentration meter 99 measures the oxygen concentration in the gas atmosphere in the chamber 6 .

[0072] The flash heating unit 5 disposed above the chamber 6 is composed of a light source including a plurality of (30 in this embodiment) xenon flash lamps FL inside a housing 51, and a reflector 52 disposed so as to cover the light source. In addition, a light radiation window 53 is installed at the bottom of the housing 51 of the flash heating unit 5. The light radiation window 53 constituting the floor portion of the flash heating unit 5 is a plate-shaped quartz window formed of quartz. By disposing the flash heating unit 5 above the chamber 6, the light radiation window 53 is opposed to the upper chamber window 63. The flash lamp FL irradiates the heat treatment space 65 with flash light from above the chamber 6 through the light radiation window 53 and the upper chamber window 63.

[0073] The plurality of flash lamps FL are rod-shaped lamps each having a long cylindrical shape, and are arranged in a plane in such a manner that the long sides thereof are parallel to each other along the main surface (that is, along the horizontal direction) of the semiconductor wafer W held in the holding portion 7. Thus, the plane formed by the arrangement of the flash lamps FL is also a horizontal plane. The area where the plurality of flash lamps FL are arranged is larger than the plane size of the semiconductor wafer W.

[0074] The xenon flash lamp FL includes: a cylindrical glass tube (discharge tube) in which xenon gas is sealed and an anode and a cathode connected to a capacitor are arranged at both ends; and a trigger electrode is attached to the outer peripheral surface of the glass tube. Xenon gas is an electrical insulator, so even if electric charge is stored in the capacitor, no electricity flows in the glass tube under normal conditions. However, when a high voltage is applied to the trigger electrode to break the insulation, the electricity stored in the capacitor flows into the glass tube instantly, and light is emitted by the excitation of xenon atoms or molecules at this time. In this xenon flash lamp FL, the electrostatic energy previously stored in the capacitor is converted into an extremely short light pulse of 0.1 milliseconds to 100 milliseconds, so it has the characteristic of being able to irradiate extremely strong light compared to a light source that is continuously lit like a halogen lamp HL. That is, the flash lamp FL is a pulse light lamp that emits light instantly in an extremely short time of less than 1 second. In addition, the light emission time of the flash lamp FL can be adjusted by the coil constant of the lamp power supply that supplies power to the flash lamp FL.

[0075] In addition, the reflector 52 is provided above the plurality of flash lamps FL so as to cover them as a whole. The basic function of the reflector 52 is to reflect the flash emitted from the plurality of flash lamps FL toward the heat treatment space 65. The reflector 52 is formed of an aluminum alloy plate, and its surface (the surface facing the flash lamp FL side) is roughened by sandblasting.

[0076] The halogen heating unit 4 disposed below the chamber 6 has a plurality of (40 in this embodiment) halogen lamps HL built inside a housing 41. The halogen heating unit 4 heats the semiconductor wafer W by irradiating light from the plurality of halogen lamps HL into the heat treatment space 65 from below the chamber 6 through the lower chamber window 64.

[0077] Figure 7 It is a top view showing the arrangement of a plurality of halogen lamps HL. 40 halogen lamps HL are arranged in two sections, upper and lower. In the upper section close to the holding portion 7, 20 halogen lamps HL are arranged, and in the lower section farther from the holding portion 7 than the upper section, 20 halogen lamps HL are also arranged. Each halogen lamp HL is a rod-shaped lamp having a long cylindrical shape. In the upper section and the lower section, the 20 halogen lamps HL are arranged in a manner that their respective long side directions are parallel to each other along the main surface of the semiconductor chip W held in the holding portion 7 (that is, along the horizontal direction). As a result, the planes formed by the arrangement of the halogen lamps HL in the upper section and the lower section are both horizontal planes.

[0078] In addition, if Figure 7As shown in the figure, in the upper and lower sections, the arrangement density of the halogen lamps HL in the area opposite to the peripheral portion of the semiconductor wafer W held by the holding portion 7 is higher than that in the area opposite to the central portion of the semiconductor wafer W held by the holding portion 7. That is, in the upper and lower sections, the arrangement spacing of the halogen lamps HL in the peripheral portion is shorter than that in the central portion of the lamp arrangement. Therefore, when heating is performed by light irradiation from the halogen heating unit 4, a larger amount of light can be irradiated to the peripheral portion of the semiconductor wafer W, which is prone to temperature drop.

[0079] In addition, the lamp group consisting of the upper halogen lamps HL and the lamp group consisting of the lower halogen lamps HL are arranged in a lattice-like manner, that is, a total of 40 halogen lamps HL are arranged in a manner such that the long sides of the 20 halogen lamps HL arranged in the upper section and the long sides of the 20 halogen lamps HL arranged in the lower section are orthogonal to each other.

[0080] The halogen lamp HL is a filament-type light source that turns the filament incandescent by energizing the filament disposed inside a glass tube, thereby emitting light. Inside the glass tube, a gas obtained by introducing a trace amount of halogen elements (iodine, bromine, etc.) into an inert gas such as nitrogen or argon is sealed. By introducing the halogen element, the breakage of the filament can be suppressed and the temperature of the filament can be set to a high temperature. Therefore, the halogen lamp HL has the characteristics of a long life and the ability to continuously irradiate strong light compared to a conventional incandescent bulb. That is, the halogen lamp HL is a continuously lit lamp that emits light continuously for at least 1 second. In addition, the halogen lamp HL is a rod-shaped lamp, so it has a long life, and by arranging the halogen lamp HL in the horizontal direction, the radiation efficiency to the semiconductor wafer W above is excellent.

[0081] In addition, in the housing 41 of the halogen heating unit 4, a reflector 43 ( Figure 1 ). The reflector 43 reflects the light emitted from the plurality of halogen lamps HL toward the heat treatment space 65 side.

[0082] The control unit 3 controls the various action mechanisms provided in the heat treatment device 1. The hardware structure of the control unit 3 is the same as that of a general computer. That is, the control unit 3 is provided with a circuit for performing various calculations, i.e., a CPU (central processing unit), a dedicated read-only memory for storing basic programs, i.e., a ROM (read-only memory), a readable and writable memory for storing various information, i.e., a RAM (random access memory), and a disk pre-stored with control software or data. The CPU of the control unit 3 executes a specific processing program to perform processing in the heat treatment device 1.

[0083] In addition to the above-mentioned structure, the heat treatment apparatus 1 is also equipped with various cooling structures to prevent the halogen heating unit 4, the flash heating unit 5, and the chamber 6 from excessive temperature rise due to the heat energy generated by the halogen lamp HL and the flash lamp FL during the heat treatment of the semiconductor wafer W. For example, a water cooling pipe (not shown) is provided on the wall of the chamber 6. In addition, the halogen heating unit 4 and the flash heating unit 5 are formed into an air cooling structure for exhausting heat by forming an air flow inside. In addition, air is also supplied to the gap between the upper chamber window 63 and the lamp radiation window 53, so that the flash heating unit 5 and the upper chamber window 63 are cooled.

[0084] Next, the heat treatment method of the present invention will be described. Figure 8 1 is a flow chart showing the sequence of the heat treatment method of the present invention. In the present embodiment, the semiconductor substrate to be treated is a silicon (Si) semiconductor wafer W. On the surface of the semiconductor wafer W, at least a portion of the silicon of the substrate is exposed. In addition, before the heat treatment method of the present invention, the surface of the semiconductor wafer W may be cleaned with hydrofluoric acid or the like in advance to remove the natural oxide film formed on the exposed portion of the silicon.

[0085] First, a silicon semiconductor wafer W is loaded into the chamber 6 of the heat treatment apparatus 1 (step S1). Specifically, the gate valve 185 is opened to open the transfer opening 66, and the semiconductor wafer W is loaded into the heat treatment space 65 in the chamber 6 through the transfer opening 66 by a transfer robot outside the apparatus. At this time, the valve 92 may be opened to supply nitrogen gas into the chamber 6, and the nitrogen gas may flow out from the transfer opening 66, so that the entrainment of external gas accompanying the loading of the semiconductor wafer W is suppressed to a minimum.

[0086] The semiconductor wafer W carried in by the transfer robot stops until it enters the position just above the holding portion 7. Then, the pair of transfer arms 11 of the transfer mechanism 10 horizontally move from the retreat position to the transfer operation position and rise, whereby the lift pins 12 protrude from the upper surface of the holding plate 75 of the crystal base 74 through the through holes 79 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.

[0087] After placing the semiconductor wafer W on the lift pins 12, the transport robot withdraws from the heat treatment space 65 and closes the transport opening 66 by the gate valve 185. Then, the pair of transfer arms 11 descends, whereby the semiconductor wafer W is transferred from the transfer mechanism 10 to the crystal seat 74 of the holding portion 7 and is held from below in a horizontal posture. The semiconductor wafer W is supported by a plurality of substrate support pins 77 vertically arranged on the holding plate 75 and held on the crystal seat 74. In addition, the semiconductor wafer W is held on the holding portion 7 with the surface where silicon is exposed in a part of the area as the upper surface. A specific gap is formed between the back surface (the main surface on the opposite side to the front side) 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 that have descended to the bottom of the crystal seat 74 are retreated to the retreat position, that is, the inner side of the recess 62, by the horizontal moving mechanism 13.

[0088] In addition, after the transfer opening 66 is closed by the gate valve 185 and the heat treatment space 65 becomes a closed space, an inert gas, i.e., a nitrogen gas atmosphere, is formed in the chamber 6 (step S2). Specifically, the valve 91 is closed and the valve 92 is opened to supply nitrogen gas to the heat treatment space 65 from the gas supply hole 81. In addition, the valve 89 is opened to discharge the gas in the chamber 6 from the gas discharge hole 86. Thus, the nitrogen gas supplied from the upper part of the heat treatment space 65 in the chamber 6 flows downward and is discharged from the lower part of the heat treatment space 65, and the chamber 6 is replaced with a nitrogen gas atmosphere. In addition, by opening the valve 192, the gas in the chamber 6 is also discharged from the transfer opening 66. Furthermore, by omitting the exhaust mechanism shown in the figure, the gas atmosphere around the drive part of the transfer mechanism 10 is also discharged. In addition, a nitrogen gas atmosphere can also be formed in the chamber 6 in advance, and a semiconductor wafer W can be moved therein.

[0089] Then, preheating (auxiliary heating) of the semiconductor wafer W is performed by the halogen lamp HL of the halogen heating section 4 (step S3). Fig. 9 2 is a diagram showing the change in the surface temperature of the semiconductor wafer W. At time t1, the 40 halogen lamps HL of the halogen heating unit 4 are all lit to start preheating the semiconductor wafer W. The halogen light emitted from the halogen lamps HL passes through the lower chamber window 64 and the crystal seat 74 formed of quartz and irradiates the back of the semiconductor wafer W. The semiconductor wafer W is preheated and its temperature rises by being irradiated with light from the halogen lamps HL. In addition, since the transfer arm 11 of the transfer mechanism 10 retreats to the inner side of the recess 62, it does not become an obstacle to the preheating performed by the halogen lamps HL.

[0090] When the halogen lamp HL is used for heat treatment, 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 lower surface of the semiconductor wafer W held on the crystal base 74 through the opening 78 through the transparent window 21 to measure the temperature of the wafer during heating. The measured temperature of the semiconductor wafer W is transmitted to the control unit 3. The control unit 3 feedback controls the output of the halogen lamp HL based on the measured value obtained by the radiation thermometer 20 so that the temperature of the semiconductor wafer W reaches the preheating temperature T2.

[0091] In addition, the control unit 3 monitors whether the temperature of the semiconductor wafer W, which is heated by the light irradiation from the halogen lamp HL, has reached a specific switching temperature T1 (step S4). The switching temperature T1 is above 400°C. When the temperature of the semiconductor wafer W reaches the switching temperature T1 in the middle of preheating, the process proceeds from step S4 to step S5, and the nitrogen gas atmosphere in the chamber 6 is replaced with an oxygen gas atmosphere. Specifically, when the temperature of the semiconductor wafer W reaches the switching temperature T1 at time t2, under the control of the control unit 3, the valve 91 is opened and oxygen is supplied to the chamber 6 from the gas supply unit 90.

[0092] By supplying oxygen into the chamber 6, a gas atmosphere containing oxygen, that is, an oxidizing gas atmosphere, is formed in the chamber 6. In the present embodiment, the temperature of the semiconductor wafer W reaching the switching temperature T1 is used as a trigger to switch the chamber 6 from the inert gas atmosphere to the oxidizing gas atmosphere. After the temperature of the semiconductor wafer W reaches the switching temperature T1, an oxygen gas atmosphere is formed in the chamber 6, thereby oxidizing the silicon exposed portion on the surface of the semiconductor wafer W, and the silicon oxide film (silicon dioxide (SiO 2 ) film) growth.

[0093] Then, after the temperature of the semiconductor wafer W reaches the preheating temperature T2 at time t3, the control unit 3 temporarily maintains the semiconductor wafer W at the preheating temperature T2. Specifically, at time t3 when the temperature of the semiconductor wafer W measured by the radiation thermometer 20 reaches the preheating temperature T2, the control unit 3 adjusts the output of the halogen lamp HL to maintain the temperature of the semiconductor wafer W approximately at the preheating temperature T2.

[0094] By preheating with the halogen lamp HL, the temperature of the semiconductor wafer W as a whole is uniformly raised to the preheating temperature T2. In the stage of preheating with the halogen lamp HL, there is a tendency that the temperature of the peripheral portion of the semiconductor wafer W, which is more likely to generate heat dissipation, is lower than that of the central portion, but the arrangement density of the halogen lamp HL in the halogen heating unit 4 is higher in the area facing the peripheral portion of the semiconductor wafer W than in the area facing the central portion of the semiconductor wafer W. Therefore, the amount of light irradiated to the peripheral portion of the semiconductor wafer W, which is more likely to generate heat dissipation, becomes larger, so that the in-plane temperature distribution of the semiconductor wafer W in the preheating stage can be uniform.

[0095] Even after the temperature of the semiconductor wafer W reaches the preheating temperature T2 at time t3, oxygen continues to be supplied into the chamber 6. Fig.10 : is a diagram showing the change of oxygen concentration in the chamber 6. The oxygen concentration in the chamber 6 is measured by the oxygen concentration meter 99. At time t2 when the temperature of the semiconductor wafer W has reached the switching temperature T1, oxygen starts to be supplied to the chamber 6 and the oxygen concentration starts to rise. After time t3 when the temperature of the semiconductor wafer W has reached the preheating temperature T2, oxygen continues to be supplied and the oxygen concentration in the chamber 6 continues to rise. Then, at time t4 when the oxygen concentration in the chamber 6 measured by the oxygen concentration meter 99 reaches the target concentration C1, the flash lamp FL of the flash heating unit 5 flash-irradiates the surface of the semiconductor wafer W held on the crystal base 74 (step S6). At this time, a part of the flash light radiated from the flash lamp FL is directed directly into the chamber 6, and another part is temporarily reflected by the reflector 52 and then directed into the chamber 6, and the semiconductor wafer W is flash-heated by the irradiation of these flash lights. In addition, the target concentration C1 can be set to an appropriate value or 100%.

[0096] Flash heating is performed by flash light irradiation from the flash lamp FL, so the surface temperature of the semiconductor wafer W can be raised in a short time. That is, the flash light irradiated from the flash lamp FL is an extremely short and strong flash light with an irradiation time of about 0.1 millisecond to 100 milliseconds, which is obtained by converting the electrostatic energy previously stored in the capacitor into an extremely short light pulse. In addition, the surface temperature of the semiconductor wafer W is instantly raised to a peak temperature T3 by the flash light irradiation from the flash lamp FL, and then the temperature is rapidly reduced. The peak temperature T3 is higher than the preheating temperature T2.

[0097] When the oxygen concentration in the chamber 6 reaches the target concentration C1, the surface of the semiconductor wafer W is heated to the peak temperature T3 by flash irradiation, thereby thermally oxidizing the silicon exposed portion and further growing the silicon oxide film. However, the flash irradiation time is an extremely short time of 0.1 milliseconds to 100 milliseconds, so that the film thickness of the silicon oxide film is prevented from exceeding the required value and becoming excessively thick. In this embodiment, the film thickness of the silicon oxide film is about 1.5 nm.

[0098] After the flash irradiation is completed, under the control of the control unit 3, the valve 91 is immediately closed to stop the supply of oxygen to the chamber 6. In addition, when nitrogen is also supplied to the chamber 6 when the oxygen gas atmosphere is formed, the valve 92 is also closed to stop the supply of nitrogen. In addition, in the state where the supply of gas to the chamber 6 is stopped, the exhaust unit 190 exhausts the gas in the chamber 6, thereby reducing the pressure in the chamber 6 to less than the atmospheric pressure (step S7).

[0099] Fig.11 1 is a diagram showing the pressure change in the chamber 6. The preheating of the semiconductor wafer W by the halogen lamp HL and the flash heating by the flash lamp FL are performed at the atmospheric pressure P1. That is, the silicon oxide film grows while the pressure in the chamber 6 is the atmospheric pressure P1. Immediately after the flash irradiation from the flash lamp FL is performed at time t4, the pressure in the chamber 6 is reduced from the atmospheric pressure P1 by the exhaust unit 190. Then, at time t5, the pressure in the chamber 6 is reduced to the atmospheric pressure P2. Fig.11 As shown, during the decompression in the chamber 6 from time t4 to time t5, the decompression is performed steadily at a relatively small exhaust flow rate in the initial stage, and then switched to a larger exhaust flow rate. If the chamber 6 is decompressed rapidly at a large exhaust flow rate at the same time as the decompression starts, there is a concern that the crystal seat 74 of thin quartz may be damaged. By switching the exhaust flow rate to two stages as in the present embodiment, damage to the crystal seat 74 can be prevented.

[0100] In addition, by reducing the pressure in the chamber 6 from time t4, as shown in FIG. Fig.10 As shown in FIG. 1 , the oxygen concentration in the chamber 6 also decreases from the target concentration C1. Fig. 9 As shown, after the flash irradiation is performed at time t4, the surface temperature of the semiconductor wafer W also drops rapidly. The oxygen concentration in the chamber 6 decreases, and the surface temperature of the semiconductor wafer W drops, whereby the growth of the silicon oxide film stops rapidly.

[0101] The temperature of the semiconductor wafer W during the cooling process after the flash irradiation is measured by the radiation thermometer 20, and the measurement result is transmitted to the control unit 3. The control unit 3 monitors whether the temperature of the semiconductor wafer W has been cooled to a specific temperature based on the measurement result of the radiation thermometer 20. In addition, by reducing the pressure in the chamber 6 to the pressure P2 by the exhaust unit 190, the oxygen in the chamber 6 is almost completely exhausted from the chamber 6, and the influence on the subsequent processing in the chamber 6 can be eliminated. At the time point when the pressure in the chamber 6 is reduced to the pressure P2 at time t5, the exhaust by the exhaust unit 190 is stopped, and the valve 92 is opened to supply nitrogen gas into the chamber 6. As a result, the chamber 6 is made into a nitrogen gas atmosphere and returned to the atmospheric pressure P1.

[0102] After the atmospheric pressure P1 of the inert gas atmosphere is restored in the chamber 6 and the temperature of the semiconductor wafer W is cooled to below a specific temperature, the pair of transfer arms 11 of the transfer mechanism 10 are horizontally moved from the retreat position to the transfer action position again and rise, whereby the lift pins 12 protrude from the upper surface of the crystal seat 74 and receive the heat-treated semiconductor wafer W from the crystal seat 74. Then, the transport opening 66 closed by the gate valve 185 is opened, and the semiconductor wafer W placed on the lift pins 12 is transported out by a transport robot outside the device, thereby completing the heating treatment of the semiconductor wafer W in the heat treatment device 1 (step S8).

[0103] In the present embodiment, when the temperature of the semiconductor wafer W reaches the switching temperature T1 in the middle of preheating, oxygen is supplied into the chamber 6 and the nitrogen gas atmosphere in the chamber 6 is switched to the oxygen gas atmosphere. Therefore, when the temperature of the semiconductor wafer W is a relatively low temperature lower than the switching temperature T1, the chamber 6 is an inert gas atmosphere, so the oxidation of silicon does not occur. Moreover, when the temperature of the semiconductor wafer W becomes a relatively high temperature higher than the switching temperature T1, the chamber 6 is switched from the inert gas atmosphere to the oxidizing gas atmosphere, silicon is oxidized, and a silicon oxide film (silicon dioxide thin film) begins to grow. As a result, when the temperature of the semiconductor wafer W is a relatively low temperature, oxidation is suppressed, and oxidation is performed after the temperature becomes high, so that a thin oxide film with good characteristics, which is dense and has fewer defects at the interface with the silicon base layer, can be formed.

[0104] In addition, in the present embodiment, a silicon oxide film is formed by irradiating a semiconductor wafer W with a flash of light with an extremely short irradiation time in an oxidizing gas atmosphere. Therefore, a nanometer-level silicon oxide film with an extremely thin film thickness can be formed. When the silicon oxide film is used as a base film of a high dielectric constant gate insulating film, an extremely thin film thickness is required, and the heat treatment method of the present invention is just suitable.

[0105] If only a thin silicon oxide film is formed, silicon dioxide can also be deposited by, for example, ALD (Atomic Layer Deposition). However, it is known that if silicon dioxide is deposited by ALD, a large number of defects will be generated at the interface between the silicon oxide film and the silicon base layer. Therefore, an annealing treatment (PDA, Post Deposition Anneal, post-deposition annealing) is required to eliminate the defects. In this embodiment, the silicon oxide film is formed by a very short-time thermal oxidation method using flash heating, so that a thin silicon oxide film with good matching with the silicon base layer, fewer defects, and nanometer-level can be formed.

[0106] Furthermore, since the silicon oxide film is formed by thermal oxidation using flash heating, even when a three-dimensional pattern of a complex shape is formed on the surface of the semiconductor wafer W, the oxide film can be uniformly formed over the entire sidewall portion including the pattern.

[0107] Furthermore, immediately after the flash irradiation, the supply of oxygen into the chamber 6 is stopped, and the chamber 6 is depressurized by the exhaust unit 190 to rapidly reduce the oxygen concentration. This can rapidly stop the growth of the silicon oxide film on the surface of the semiconductor wafer W and appropriately control its film thickness.

[0108] The above is a description of the embodiment of the present invention, but various changes other than the above contents may be made to the invention without departing from the main purpose thereof. For example, in the above embodiment, oxygen is supplied to the chamber 6 to form an oxidizing gas atmosphere, but this is not limited to this, and oxidizing gases such as ozone, oxygen free radicals, and water vapor may also be used. That is, as long as an oxidizing gas that oxidizes silicon is supplied to the chamber 6 to form an oxidizing gas atmosphere. In particular, if an oxidizing gas with a strong oxidizing power such as ozone is used, a thinner oxide film with better characteristics, which is denser and has fewer defects at the interface with the silicon-based layer, can be formed.

[0109] In addition, when replacing the nitrogen gas atmosphere in the chamber 6 with the oxygen gas atmosphere, the valve 92 can be closed and only oxygen gas can be supplied to the chamber 6, or the valve 92 can be opened and a mixed gas of oxygen and nitrogen gas can be supplied to the chamber 6. When replacing the nitrogen gas atmosphere with the oxidizing gas atmosphere, if an inert gas is mixed in the oxygen and supplied to the chamber 6, the haze of the surface of the semiconductor wafer W can be suppressed from deteriorating, thereby forming a dense and thin oxide film with good characteristics and fewer defects at the interface with the silicon base layer. In addition, the inert gas mixed in the oxygen is not limited to nitrogen, and can also be argon (Ar) or xenon (Xe).

[0110] Furthermore, when the pressure in the chamber 6 is reduced after the flash irradiation, the pressure in the chamber 6 can be reduced to less than the atmospheric pressure by causing the exhaust unit 190 to exhaust the gas in the chamber 6 while supplying nitrogen gas into the chamber 6. In this case, the exhaust flow rate of the exhaust unit 190 is naturally greater than the supply flow rate of the nitrogen gas into the chamber 6.

[0111] Furthermore, when the pressure in the chamber 6 is reduced after the flash irradiation, the gas supplied to the chamber 6 may be an inert gas such as argon or xenon instead of nitrogen. In particular, when the supply of oxygen to the chamber 6 is stopped after the flash irradiation and argon or xenon is supplied to the chamber 6, the crystallinity of the surface layer is improved by controlling the outer diffusion of oxygen on the surface of the semiconductor wafer W, and a thin oxide film with good characteristics, which is dense and has few defects at the interface with the silicon base layer, can be formed.

[0112] Furthermore, when the pressure in the chamber 6 is reduced after the flash irradiation, the gas supplied into the chamber 6 may be hydrogen gas (H 2After the flash irradiation, the supply of oxygen to the chamber 6 is stopped and hydrogen is supplied to the chamber 6 to perform hydrogen sintering, thereby forming a thinner oxide film with better characteristics and fewer defects at the interface with the silicon base layer.

[0113] In addition, the pressure in the chamber 6 may be reduced to a pressure lower than the atmospheric pressure before the preheating by the halogen lamp HL. This can eliminate the influence of the gas atmosphere of the previous process.

[0114] In addition, by performing the same preheating and flash heating treatment as in the above embodiment on the semiconductor wafer W in which the impurities are implanted in the source / drain regions, the impurities implanted in the semiconductor wafer W can be activated while an oxide film is formed on the surface of the semiconductor wafer W. This arrangement can reduce the number of processing steps for the semiconductor wafer W. In the case where silicon in the source / drain regions is exposed, the impurities can be activated while a protective oxide film is formed in the regions.

[0115] In addition, in the above embodiment, an oxide film is formed on the semiconductor wafer W of single crystal silicon, but an oxide film may also be formed on polycrystalline silicon. In this case, an oxide film is also formed on polycrystalline silicon by the same heat treatment method as in the above embodiment. Since there are more grain boundaries in polycrystalline silicon than in single crystal silicon, the oxidation rate of polycrystalline silicon is generally higher than that of single crystal silicon, and the oxide film of polycrystalline silicon tends to become thicker. However, if an oxide film is formed on polycrystalline silicon by the heat treatment method of the present invention, since the oxide film is formed by irradiation of a flash with an extremely short irradiation time, even for polycrystalline silicon with a relatively high oxidation rate, precise film thickness control can be performed.

[0116] In addition, in the above embodiment, an oxide film is formed on the silicon semiconductor wafer W, but the present invention is not limited thereto, and an oxide film may be formed on germanium (Ge). In this case, an extremely thin oxide film (GeO2) may be formed on germanium by the same heat treatment method as in the above embodiment. x ).

[0117] In the above embodiment, the flash heating unit 5 is provided with 30 flash lamps FL, but the present invention is not limited thereto, and the number of flash lamps FL can be set to any number. In addition, the flash lamp FL is not limited to a xenon flash lamp, and can also be a krypton flash lamp. In addition, the number of halogen lamps HL provided in the halogen heating unit 4 is not limited to 40, and can be set to any number.

[0118] In addition, in the embodiment, a filament-type halogen lamp HL is used as a continuous-lighting lamp that emits light continuously for more than 1 second to preheat the semiconductor chip W, but this is not limited to this. A discharge-type arc lamp (for example, a xenon arc lamp) may be used instead of the halogen lamp HL as a continuous-lighting lamp for preheating.

[0119] [Explanation of Symbols]

[0120] 1 Heat treatment device

[0121] 3. Control Unit

[0122] 4 Halogen heating unit

[0123] 5 Flash heating unit

[0124] 6 Chamber

[0125] 7. Maintaining part

[0126] 10 Transfer mechanism

[0127] 65 Heat treatment space

[0128] 74 Crystal seat

[0129] 75 Holding Plate

[0130] 77 Base plate support pin

[0131] 83 Supply piping

[0132] 90 Gas supply unit

[0133] 93 Oxygen Supply

[0134] 94 Nitrogen supply source

[0135] 99 Oxygen concentration meter

[0136] 190 Exhaust

[0137] FL Flash

[0138] HL halogen lamp

[0139] W Semiconductor Wafer

Claims

1. A heat treatment method, characterized in that: The invention forms an oxide film by irradiating a substrate with light to heat the substrate, and comprises: a receiving step of receiving the substrate into the chamber; a heating step of irradiating light onto the substrate to heat the substrate; and a gas atmosphere switching step, in which, when the substrate reaches a specific switching temperature during the heating step, ozone is supplied into the chamber to switch the chamber from an inert gas atmosphere to an oxidizing gas atmosphere; The heating process comprises: a preheating step of irradiating light to the substrate from a continuously lit lamp; and a flash heating step of irradiating the substrate with a flash lamp after the preheating step; After the flash irradiation of the heating step is completed, immediately stopping the supply of the ozone into the chamber; Before the preheating temperature of the preheating step is reached, supply of the ozone into the chamber is started.

2. The heat treatment method according to claim 1, characterized in that: When the concentration of the ozone in the chamber reaches a specific value, the flash is irradiated.

3. The heat treatment method according to claim 1, characterized in that: An oxide film is formed on the surface of the substrate by irradiating the substrate with a flash of light, and impurities implanted into the substrate are activated.

4. The heat treatment method according to any one of claims 1 to 3, characterized in that: After the heating step is completed, the supply of the ozone into the chamber is stopped, and the pressure in the chamber is reduced.

5. The heat treatment method according to claim 1, characterized in that: The substrate is a silicon substrate.

6. The heat treatment method according to claim 5, characterized in that: In the gas atmosphere switching step, an inert gas is mixed with the ozone and the mixed gas is supplied into the chamber.

7. The heat treatment method according to claim 5 or 6, characterized in that: The switching temperature is above 400°C.

8. A heat treatment method, characterized in that: The invention forms an oxide film by irradiating a substrate with light to heat the substrate, and comprises: A receiving step of receiving the substrate into the chamber; a heating step of irradiating light onto the substrate to heat the substrate; and a gas atmosphere switching step, in which, when the substrate reaches a specific switching temperature during the heating step, ozone is supplied into the chamber to switch the chamber from an inert gas atmosphere to an oxidizing gas atmosphere; The heating process comprises: a preheating step of irradiating light to the substrate from a continuously lit lamp; and a flash heating step of irradiating the substrate with a flash lamp after the preheating step; After the flash irradiation in the heating step is completed, the supply of the ozone into the chamber is immediately stopped, and hydrogen gas is supplied into the chamber.

9. A heat treatment method, characterized in that: The invention forms an oxide film by irradiating a substrate with light to heat the substrate, and comprises: A receiving step of receiving the substrate into the chamber; a heating step of irradiating light onto the substrate to heat the substrate; and a gas atmosphere switching step, in which, when the substrate reaches a specific switching temperature during the heating step, ozone is supplied into the chamber to switch the chamber from an inert gas atmosphere to an oxidizing gas atmosphere; The heating process comprises: a preheating step of irradiating light to the substrate from a continuously lit lamp; and a flash heating step of irradiating the substrate with a flash lamp after the preheating step; After the flash irradiation in the heating step is completed, the supply of the ozone into the chamber is immediately stopped, and argon gas or xenon gas is supplied into the chamber.

10. A heat treatment device, characterized in that: The invention forms an oxide film by irradiating a substrate with light to heat the substrate, and comprises: a chamber for receiving a substrate; a light irradiation unit for irradiating light to the substrate to heat the substrate; a gas supply unit for supplying ozone into the chamber; and a control unit that controls the gas supply unit so that, when the substrate reaches a specific switching temperature while being heated by light irradiation from the light irradiation unit, the ozone is supplied into the chamber to switch the chamber from an inert gas atmosphere to an oxidizing gas atmosphere; The light irradiation unit comprises: Continuously lighting the lamp to irradiate the substrate with light to preheat the substrate; and a flash lamp, which irradiates a flash of light to the substrate after the preheating; and After the flash irradiation from the flash lamp ends, the gas supply unit immediately stops supplying the ozone into the chamber; The control unit controls the gas supply unit so as to start supplying the ozone into the chamber before the preheating temperature of the preheating is reached.

11. The heat treatment device according to claim 10, characterized in that: The flash lamp radiates the flash when the concentration of the ozone in the chamber reaches a specific value.

12. The heat treatment device according to claim 10, characterized in that: The flash lamp irradiates the substrate with flash light to form an oxide film on the surface of the substrate and activate the impurities injected into the substrate.

13. The heat treatment device according to any one of claims 10 to 12, characterized in that A decompression unit is further provided for decompressing the chamber, and After the heating of the substrate by the light irradiation from the light irradiation unit is completed, the gas supply unit stops supplying the ozone into the chamber, and the decompression unit decompresses the chamber.

14. The heat treatment device according to claim 10, characterized in that: The substrate is a silicon substrate.

15. The heat treatment device according to claim 14, characterized in that: The gas supply unit mixes an inert gas with the ozone and supplies the mixed gas into the chamber.

16. The heat treatment device according to claim 14 or 15, characterized in that: The switching temperature is above 400°C.

17. A heat treatment device, characterized in that: The invention forms an oxide film by irradiating a substrate with light to heat the substrate, and comprises: a chamber for receiving a substrate; a light irradiation unit for irradiating light to the substrate to heat the substrate; a gas supply unit for supplying ozone into the chamber; and a control unit that controls the gas supply unit so that, when the substrate reaches a specific switching temperature while being heated by light irradiation from the light irradiation unit, the ozone is supplied into the chamber to switch the chamber from an inert gas atmosphere to an oxidizing gas atmosphere; The light irradiation unit comprises: Continuously lighting the lamp to irradiate the substrate with light to preheat the substrate; and a flash lamp, which irradiates a flash of light to the substrate after the preheating; and After the flash irradiation from the flash lamp ends, the gas supply unit immediately stops supplying the ozone into the chamber and supplies hydrogen gas into the chamber.

18. A heat treatment device, characterized in that: The invention forms an oxide film by irradiating a substrate with light to heat the substrate, and comprises: a chamber for receiving a substrate; a light irradiation unit for irradiating light to the substrate to heat the substrate; a gas supply unit for supplying ozone into the chamber; and a control unit that controls the gas supply unit so that, when the substrate reaches a specific switching temperature while being heated by light irradiation from the light irradiation unit, the ozone is supplied into the chamber to switch the chamber from an inert gas atmosphere to an oxidizing gas atmosphere; The light irradiation unit comprises: Continuously lighting the lamp to irradiate the substrate with light to preheat the substrate; and a flash lamp, which irradiates a flash of light to the substrate after the preheating; and After the flash irradiation from the flash lamp ends, the gas supply unit immediately stops supplying the ozone into the chamber and supplies argon gas or xenon gas into the chamber.

Images