Heat treatment method and heat treatment device

Abstract

Provided are a heat treatment method and a heat treatment device capable of suppressing the increase in the film thickness of a silicon dioxide film at the base layer of a high dielectric constant film. A high dielectric constant film is formed on the surface of a silicon semiconductor wafer via a silicon dioxide film as an interface layer film. After the semiconductor wafer is accommodated in a chamber, the pressure in the chamber is reduced to a pressure (P1) lower than the atmospheric pressure. Then, a mixed gas of ammonia and nitrogen is supplied into the chamber to restore it to normal pressure (Ps), and a flash is irradiated onto the surface of the semiconductor wafer to perform post-film formation heat treatment of the high dielectric constant film. Since the pressure in the chamber is restored once it is reduced to a pressure (P1) lower than the atmospheric pressure, the oxygen concentration in the chamber when performing post-film formation heat treatment can be significantly reduced, thereby suppressing the silicon dioxide film at the base layer of the high dielectric constant film from absorbing oxygen and increasing its film thickness during the post-film formation heat treatment.

Description

[0001] This application is a divisional application of a patent application with application number CN201610730607.4, application date August 26, 2016, and invention name “Heat treatment method and heat treatment device”. Technical Field

[0002] The present invention relates to a heat treatment method and a heat treatment apparatus for heating a thin plate-shaped precision electronic substrate (hereinafter referred to as a "substrate") such as a semiconductor wafer having a high dielectric constant film or a metal gate formed on the high dielectric constant film by irradiating the substrate with a flash. Background Art

[0003] In the manufacturing process of semiconductor devices, flash lamp annealing (FLA) for heating semiconductor wafers in a very short time has attracted much attention. Flash lamp annealing is a heat treatment technology that uses a xenon flash lamp (hereinafter referred to as a "flash lamp" to refer to a xenon flash lamp) to irradiate the surface of a semiconductor wafer with a flash light, thereby raising the temperature of only the surface of the semiconductor wafer in a very short time (several milliseconds or less).

[0004] The radiation spectrum of the xenon flash lamp is distributed from the ultraviolet region to the near infrared region, and the wavelength is shorter than that of the conventional halogen lamp, and is almost consistent with the basic absorption band of the silicon semiconductor wafer. Therefore, when the xenon flash lamp irradiates the semiconductor wafer with a flash, the transmitted light can at least rapidly heat up the semiconductor wafer. In addition, if the flash is irradiated in an extremely short time of less than a few milliseconds, it is possible to selectively heat only the vicinity of the surface of the semiconductor wafer.

[0005] Such flash lamp annealing is used for a process that requires heating in a very short time, for example, it is typically used for activation of impurities implanted into a semiconductor wafer. If a flash of light is irradiated from a flash lamp onto the surface of a semiconductor wafer into which impurities have been implanted by ion implantation, the surface of the semiconductor wafer can be heated to an activation temperature in a very short time, and only activation of the impurities can be performed without deep diffusion of the impurities.

[0006] In addition, as a gate insulating film of a field effect transistor (FET) developed in recent years, the application of a high dielectric constant film (High-k film) using a material (high dielectric constant material) having a higher dielectric constant than silicon dioxide (SiO2) has been studied. The high dielectric constant film is a film that has been developed as a new stacked structure together with a metal gate using a metal as the gate in order to solve the problem of increased leakage current as the thin film of the gate insulating film progresses. The application of flash lamp annealing to the heat treatment of a semiconductor wafer having a new stacked structure including such a high dielectric constant film has also been studied.

[0007] The high dielectric constant film is formed by depositing a high dielectric constant material on a silicon substrate by methods such as metal organic chemical vapor deposition (MOCVD). Although the high dielectric constant film has a higher dielectric constant than the conventional silicon dioxide film, the deposited high dielectric constant film has low crystallinity and contains many defects such as point defects. Therefore, the following heat treatment method is proposed in, for example, patent document 1, that is, it is necessary to anneal the deposited high dielectric constant film at a high temperature, and irradiate a flash of light to the surface of the semiconductor wafer formed with the high dielectric constant film for a short time for heat treatment.

[0008] Patent Document 1: Japanese Patent Application Publication No. 2013-73946

[0009] However, as shown in Patent Document 1, when flash heating is performed only for a very short time by irradiating a semiconductor wafer with a high dielectric constant film, the following problem occurs: the film thickness of the silicon dioxide film formed on the base layer of the high dielectric constant film increases, and a high dielectric constant cannot be obtained. The increase in the film thickness of the silicon dioxide film is caused by performing the heating treatment in the presence of oxygen. The oxygen that causes the increase in film thickness mainly includes residual oxygen in the chamber, oxygen attached to the surface of the semiconductor wafer (typically adsorbed as moisture), and oxygen dissolved in the high dielectric constant film itself. In particular, during the flash heating treatment, the oxygen remaining in the chamber becomes the main cause of the increase in the film thickness of the silicon dioxide film. Generally speaking, in a flash lamp annealing device, since the semiconductor wafer is moved in and out of the chamber at normal pressure, the oxygen in the atmosphere that flows in at this time remains in the chamber, and the oxygen concentration becomes high.

[0010] In addition, when a semiconductor wafer having a metal gate deposited on a high dielectric constant film is flash heated, there is also a problem that oxygen diffuses through the metal gate and the high dielectric constant film, increasing the thickness of the underlying silicon dioxide film and oxidizing the metal gate itself. Summary of the invention

[0011] 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 suppressing an increase in the film thickness of a silicon dioxide film serving as a base layer of a high dielectric constant film.

[0012] In order to solve the above-mentioned problems, the heat treatment method of the invention according to the first technical solution is characterized in that:

[0013] A method for heat treatment is performed by irradiating a flash of light onto a substrate having a high dielectric constant film formed thereon to heat the substrate, the method comprising:

[0014] In the loading step, the substrate with the high dielectric constant film is loaded into the chamber.

[0015] a decompression step of reducing the pressure in the chamber to a first pressure lower than atmospheric pressure,

[0016] a pressure recovery step of recovering the pressure in the chamber from a first pressure to a second pressure higher than the first pressure,

[0017] The irradiation step irradiates the surface of the substrate with flash light from a flash lamp while maintaining the pressure in the chamber at a second pressure.

[0018] Furthermore, the invention according to claim 2 is characterized in that, in the heat treatment method according to claim 1,

[0019] In the pressure restoring step, a reactive gas including ammonia gas is introduced into the chamber.

[0020] Furthermore, the invention according to claim 3 is characterized in that, in the heat treatment method according to claim 2,

[0021] The first pressure is less than 1 percent of the second pressure.

[0022] Furthermore, the invention according to claim 4 is characterized in that, in the heat treatment method according to claim 2 or claim 3,

[0023] The method further comprises a preheating step of heating the substrate to a predetermined preheating temperature before the irradiation step.

[0024] In the preheating step, the reactive gas is supplied into the chamber, and after the irradiation step, the supply of the reactive gas into the chamber is stopped.

[0025] Furthermore, the invention according to claim 5 is characterized in that, in the heat treatment method according to claim 4,

[0026] When the supply of the reactive gas is stopped, the pressure reduction in the chamber is started.

[0027] In addition, the invention according to claim 6 is characterized in that, in the heat treatment method according to any one of the inventions of claim 1 to claim 5,

[0028] The second pressure is higher than the first pressure and lower than atmospheric pressure.

[0029] The invention according to claim 7 is characterized in that, in the heat treatment method according to any one of the first to fifth inventions,

[0030] The second pressure is atmospheric pressure.

[0031] The invention according to claim 8 is characterized in that, in the heat treatment method according to any one of the first to fifth claims,

[0032] The second pressure is higher than atmospheric pressure.

[0033] In addition, the invention according to claim 9 is characterized in that, in the heat treatment method according to any one of the first to eighth claims,

[0034] In the decompression step, the exhaust flow rate from the chamber is increased with the passage of time.

[0035] The invention according to claim 10 is characterized in that, in the heat treatment method according to any one of the first to ninth claims,

[0036] In the pressure recovery step, a flow rate of gas supplied to the chamber is increased with the passage of time.

[0037] The invention according to claim 11 is characterized in that, in the heat treatment method according to any one of the first to tenth inventions,

[0038] After the irradiation step, after exhausting the gas in the chamber, an inert gas is supplied into the chamber to return the pressure to atmospheric pressure, and the inert gas is flowed into the chamber at a flow rate of 50 L / min to 100 L / min.

[0039] In addition, the heat treatment device of the invention according to claim 12 is characterized in that:

[0040] A substrate having a high dielectric constant film formed thereon is heated by irradiating a flash of light to the substrate, wherein the heat treatment apparatus comprises:

[0041] a chamber accommodating the substrate,

[0042] a flash lamp that radiates a flash of light toward the substrate contained in the chamber,

[0043] an exhaust portion for exhausting the gas in the chamber,

[0044] a gas supply unit for supplying a predetermined processing gas to the chamber,

[0045] A control unit controls the exhaust unit and the gas supply unit so that after the pressure in the chamber is reduced to a first pressure lower than the atmospheric pressure and then restored to a second pressure higher than the first pressure, a flash is irradiated from the flash lamp onto the surface of the substrate.

[0046] Furthermore, the invention according to claim 13 is characterized in that, in the heat treatment device according to claim 12,

[0047] The gas supply unit supplies a reactive gas including ammonia gas into the chamber when restoring the pressure in the chamber from the first pressure to the second pressure.

[0048] Furthermore, the invention according to claim 14 is characterized in that, in the heat treatment device according to claim 13,

[0049] The first pressure is less than 1 percent of the second pressure.

[0050] Furthermore, the invention according to claim 15 is characterized in that, in the heat treatment device according to claim 13 or claim 14,

[0051] The method further comprises a preheating unit for heating the substrate to a predetermined preheating temperature before irradiating the flash.

[0052] The control unit controls the exhaust unit and the gas supply unit so that the reactive gas is supplied into the chamber when the substrate is preheated by the preheating unit, and the supply of the reactive gas into the chamber is stopped after the flash is irradiated.

[0053] Furthermore, the invention according to claim 16 is characterized in that, in the heat treatment device according to claim 15,

[0054] The control unit controls the exhaust unit and the gas supply unit so as to stop supply of the reactive gas and start depressurizing the chamber.

[0055] In addition, the invention of claim 17 is characterized in that, in the heat treatment device of any one of the inventions of claim 12 to claim 16,

[0056] The second pressure is higher than the first pressure and lower than atmospheric pressure.

[0057] In addition, the invention according to claim 18 is characterized in that, in the heat treatment device according to any one of the inventions according to claim 12 to claim 16,

[0058] The second pressure is atmospheric pressure.

[0059] In addition, the invention of claim 19 is characterized in that, in the heat treatment device of any one of the inventions of claim 12 to claim 16,

[0060] The second pressure is higher than atmospheric pressure.

[0061] In addition, the invention of claim 20 is characterized in that, in the heat treatment device of any one of the inventions of claim 12 to claim 19,

[0062] The control unit controls the exhaust unit so that the exhaust flow rate from the chamber increases with time when the pressure in the chamber is reduced to the first pressure.

[0063] In addition, the invention according to claim 21 is characterized in that, in the heat treatment device according to any one of the inventions according to claim 12 to claim 20,

[0064] The control unit controls the gas supply unit so that the flow rate of the gas supplied to the chamber increases with time when the pressure in the chamber is restored from the first pressure to the second pressure.

[0065] In addition, the invention according to claim 22 is characterized in that, in the heat treatment device according to any one of the inventions according to claim 12 to claim 21,

[0066] The control unit controls the exhaust unit and the gas supply unit so that after irradiating the flash, when the gas in the chamber is exhausted and then inert gas is supplied into the chamber to restore the pressure to atmospheric pressure, the inert gas flows into the chamber at a flow rate of 50L / min to 100L / min.

[0067] The present invention provides a heat treatment method, characterized in that a substrate is heated by irradiating a flash of light onto a substrate having a high dielectric constant film formed thereon, the heat treatment method comprising:

[0068] In the loading step, the substrate with the high dielectric constant film is loaded into the chamber.

[0069] a decompression step of reducing the pressure in the chamber to a first pressure lower than atmospheric pressure,

[0070] a pressure recovery step of supplying an oxygen-based reactive gas into the chamber to recover the pressure in the chamber from a first pressure to a second pressure higher than the first pressure,

[0071] The irradiation step irradiates the surface of the substrate with flash light from a flash lamp while maintaining the pressure in the chamber at a second pressure.

[0072] Furthermore, the present invention is characterized in that the oxygen-based reactive gas is ozone.

[0073] In addition, the present invention is characterized in that the second pressure is higher than the first pressure and lower than atmospheric pressure.

[0074] Furthermore, the present invention is characterized in that the second pressure is atmospheric pressure.

[0075] Furthermore, the present invention is characterized in that the second pressure is higher than atmospheric pressure.

[0076] In addition, the present invention is characterized in that the irradiation time of the flash light is not less than 0.1 milliseconds and not more than 100 milliseconds.

[0077] The present invention provides a heat treatment method, characterized in that a substrate is heated by irradiating a flash of light onto a substrate having a high dielectric constant film formed thereon, the heat treatment method comprising:

[0078] In the loading step, the substrate with the high dielectric constant film is loaded into the chamber.

[0079] a decompression step of reducing the pressure in the chamber to a first pressure lower than atmospheric pressure,

[0080] a pressure recovery step of recovering the pressure in the chamber from a first pressure to a second pressure higher than the first pressure so that the oxygen concentration in the chamber is less than 200 ppb,

[0081] In the irradiation step, a flash light is irradiated from a flash lamp onto the surface of the substrate while the pressure in the chamber is maintained at a second pressure and the oxygen concentration is maintained at 200 ppb or less.

[0082] Furthermore, the present invention is characterized in that, in the pressure restoring step, a reactive gas containing ammonia gas is introduced into the chamber.

[0083] In addition, the present invention is characterized in that the second pressure is higher than the first pressure and lower than atmospheric pressure.

[0084] Furthermore, the present invention is characterized in that the second pressure is atmospheric pressure.

[0085] Furthermore, the present invention is characterized in that the second pressure is higher than atmospheric pressure.

[0086] In addition, the present invention is characterized in that the irradiation time of the flash light is not less than 0.1 milliseconds and not more than 100 milliseconds.

[0087] The present invention provides a heat treatment method, characterized in that a substrate is heated by irradiating a flash of light onto a substrate having a high dielectric constant film formed thereon, the heat treatment method comprising:

[0088] The step of carrying in is to carry the substrate into the chamber, wherein the substrate has a high dielectric constant film formed on the base material via an interface layer film, and a metal gate is also formed on the high dielectric constant film.

[0089] a decompression step of reducing the pressure in the chamber to a first pressure lower than atmospheric pressure,

[0090] a pressure recovery step of recovering the pressure in the chamber from a first pressure to a second pressure higher than the first pressure,

[0091] The irradiation step irradiates the surface of the substrate with flash light from a flash lamp while maintaining the pressure in the chamber at a second pressure.

[0092] In addition, the present invention is characterized in that the interface layer film is a silicon oxide film.

[0093] In addition, the present invention is characterized in that the metal gate is formed of titanium nitride, titanium aluminum or tungsten.

[0094] Furthermore, the present invention is characterized in that, in the pressure restoring step, a reactive gas containing ammonia gas is introduced into the chamber.

[0095] In addition, the present invention is characterized in that the second pressure is higher than the first pressure and lower than atmospheric pressure.

[0096] Furthermore, the present invention is characterized in that the second pressure is atmospheric pressure.

[0097] Furthermore, the present invention is characterized in that the second pressure is higher than atmospheric pressure.

[0098] In addition, the present invention is characterized in that the irradiation time of the flash light is not less than 0.1 milliseconds and not more than 100 milliseconds.

[0099] According to the invention of the first to eleventh technical solutions, since the pressure in the chamber is reduced to a first pressure lower than the atmospheric pressure and then restored to a second pressure higher than the first pressure, the oxygen concentration in the chamber during the flash irradiation can be reduced, thereby suppressing the increase in the film thickness of the silicon dioxide film at the base layer of the high dielectric constant film.

[0100] In particular, according to the invention of claim 3, since the first pressure is less than 1% of the second pressure, the influence of the residual air on the reactive gas can be reduced.

[0101] In particular, according to the invention of the fourth technical solution, since reactive gas is supplied into the chamber during the preheating process and the supply of reactive gas into the chamber is stopped after the irradiation process, the high dielectric constant film can be nitrided to a certain extent, thereby allowing hydrogen that has entered the high dielectric constant film to be separated.

[0102] In particular, according to the invention of the sixth technical solution, since the second pressure is higher than the first pressure and lower than the atmospheric pressure, the mean free path during the irradiation flash can be lengthened, thereby making the heat treatment reaction of the high dielectric constant film uniform. In addition, since the time required for pressure recovery is shortened, the production capacity can be improved.

[0103] In particular, according to the eighth aspect of the invention, since the second pressure is higher than the atmospheric pressure, even if the treatment temperature during the flash irradiation is lowered, the heat treatment reaction of the high dielectric constant film can be performed.

[0104] In particular, according to the invention of claim 9, since the exhaust flow rate from the chamber is increased with time, it is possible to prevent particles from being swirled up due to the exhaust from the chamber.

[0105] In particular, according to the invention of claim 10, since the flow rate of the gas supplied to the chamber is increased with the passage of time, it is possible to prevent the particles from being rolled up due to the gas supply to the chamber.

[0106] In particular, according to the invention of the eleventh technical solution, since inert gas is supplied into the chamber after the gas in the chamber is exhausted and restored to atmospheric pressure, the inert gas flows into the chamber at a flow rate of 50L / min to 100L / min, and therefore, the particles generated during flash irradiation can be flushed out of the chamber.

[0107] According to the invention of the twelfth to twenty-second technical solutions, since the pressure in the chamber is reduced to a first pressure lower than the atmospheric pressure and then restored to a second pressure higher than the first pressure, the oxygen concentration in the chamber during the flash irradiation can be reduced, thereby suppressing the increase in the film thickness of the silicon dioxide film at the base layer of the high dielectric constant film.

[0108] In particular, according to the invention of claim 14, since the first pressure is less than 1 percent of the second pressure, the influence of the residual air on the reactive gas can be reduced.

[0109] In particular, according to the invention of the fifteenth technical solution, since the reactive gas is supplied into the chamber when the substrate is preheated, and the supply of the reactive gas into the chamber is stopped after the flash is irradiated, the high dielectric constant film can be nitrided to a certain extent, and the hydrogen that has entered the high dielectric constant film can be separated.

[0110] In particular, according to the invention of the seventeenth technical solution, since the second pressure is higher than the first pressure and lower than the atmospheric pressure, the mean free path during the irradiation flash can be lengthened, thereby making the heat treatment reaction of the high dielectric constant film uniform. In addition, since the time required for pressure recovery is shortened, the production capacity can be improved.

[0111] In particular, according to the invention of claim 19, since the second pressure is higher than the atmospheric pressure, even if the processing temperature during the flash irradiation is lowered, the heat treatment reaction of the high dielectric constant film can be performed.

[0112] In particular, according to the invention of the twentieth technical solution, since the exhaust part is controlled so that when the pressure in the chamber is reduced to the first pressure, the exhaust flow rate from the chamber increases with the passage of time, thereby preventing the rolling up of particles caused by the exhaust from the chamber.

[0113] In particular, according to the invention of the twenty-first technical solution, since the gas supply part is controlled so that when the pressure in the chamber is restored from the first pressure to the second pressure, the gas supply flow rate supplied to the chamber increases with the passage of time, thereby also preventing the rolling up of particles caused by the gas supply to the chamber.

[0114] In particular, according to the invention of the twenty-second technical solution, after the flash is irradiated, when inactive gas is supplied into the chamber after the gas in the chamber is exhausted and restored to atmospheric pressure, the inactive gas flows into the chamber at a flow rate of 50L / min to 100L / min, thereby flushing the particles generated during the flash irradiation out of the chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0115] Figure 1 It is a longitudinal sectional view showing the structure of the heat treatment apparatus of the present invention.

[0116] Figure 2 It is a perspective view showing the overall appearance of the holding portion.

[0117] Figure 3 This is a plan view of the holding portion as seen from above.

[0118] Figure 4 This is a side view of the holding portion as seen from the side.

[0119] Figure 5 It is a top view of the transfer mechanism.

[0120] Figure 6 It is a side view of the transfer mechanism.

[0121] Figure 7 It is a top view showing the arrangement of a plurality of halogen lamps.

[0122] Figure 8 It is a figure which shows the structure of an exhaust part.

[0123] Fig. 9 A diagram showing a stacked structure in which a high dielectric constant film is formed on a semiconductor wafer.

[0124] Fig.10 It is a diagram showing the pressure change in the chamber in the first embodiment.

[0125] Fig.11 It is a diagram showing the pressure change in the chamber in the second embodiment.

[0126] Fig.12 It is a diagram showing the pressure change in the chamber in the third embodiment.

[0127] The reference numerals are described as follows:

[0128] 1 Heat treatment device

[0129] 3. Control Unit

[0130] 4 Halogen heating unit

[0131] 5 Flash heating unit

[0132] 6 Chamber

[0133] 7. Maintaining part

[0134] 10 Transfer mechanism

[0135] 61 Chamber side

[0136] 63 Upper chamber window

[0137] 64 Lower chamber window

[0138] 65 Heat treatment space

[0139] 74 Base

[0140] 85 Gas supply source

[0141] 90, 196 flow control valve

[0142] 101 Substrate

[0143] 102 Silicon dioxide film

[0144] 103 High dielectric constant film

[0145] 190 Exhaust

[0146] 191 Exhaust Pump

[0147] 192, 193, 194 Exhaust valve

[0148] 197, 198, 199 Bypass path

[0149] FL Flash

[0150] HL halogen lamp

[0151] W Semiconductor Wafer DETAILED DESCRIPTION

[0152] Next, refer to the attached Figure 1 Embodiments of the present invention will be described in detail.

[0153] <First Embodiment>

[0154] Figure 1 1 is a longitudinal sectional view showing the structure of a heat treatment apparatus 1 of the present invention. The heat treatment apparatus 1 of the present embodiment is a flash lamp annealing apparatus, which heats a semiconductor wafer W in the shape of a disk as a substrate by irradiating a flash of light to the semiconductor wafer W. The size of the semiconductor wafer W to be processed is not particularly limited, and may be, for example, or A high dielectric constant film is formed on the semiconductor wafer W before being carried into the heat treatment apparatus 1, and a post-film heat treatment (PDA: Post Deposition Annealing) of the high dielectric constant film is performed by the heat treatment in the heat treatment apparatus 1. Figure 1 In the following figures, the size and number of each part are exaggerated or simplified as necessary to facilitate understanding.

[0155] The heat treatment device 1 has 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. In addition, the heat treatment device 1 has 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 device. Furthermore, the heat treatment device 1 has a control unit 3, which controls the halogen heating unit 4, the flash heating unit 5, and each action mechanism provided in the chamber 6 to perform heat treatment of the semiconductor wafer W.

[0156] 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 block the upper opening, and a lower chamber window 64 is installed at the lower opening to block the lower opening. The upper chamber window 63 constituting the top 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 bottom 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. The thickness of the upper chamber window 63 and the lower chamber window 64 is, for example, about 28 mm.

[0157] 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. Both reflection rings 68 and 69 are 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 not shown in the figure. That is, the reflection rings 68 and 69 can be freely installed on the chamber side portion 61. 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.

[0158] 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, and surrounds the holding portion 7 that holds the semiconductor wafer W.

[0159] The chamber side portion 61 and the reflection rings 68 and 69 are formed of a metal material (such as stainless steel) having excellent strength and heat resistance. In addition, the inner peripheral surfaces of the reflection rings 68 and 69 are formed into mirror surfaces by electrolytic nickel plating.

[0160] In addition, a transport opening (furnace port) 66 for carrying in and carrying out semiconductor wafers W relative to the chamber 6 is provided on the chamber side portion 61. The transport opening 66 is 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 in and carried out from the heat treatment space 65 through the recess 62 from the transport opening 66. In addition, when the gate valve 185 closes the transport opening 66, the heat treatment space 65 in the chamber 6 becomes a closed space.

[0161] In addition, a gas supply hole 81 for supplying a processing gas (nitrogen (N2) and ammonia (NH3) in this embodiment) to the heat treatment space 65 is provided at the upper portion of the inner wall of the chamber 6. The gas supply hole 81 is located at an upper side position than the recess 62, and may also be provided on the reflection ring 68. The gas supply hole 81 is connected to the gas supply pipe 83 via a buffer space 82 formed in an annular shape inside the side wall of the chamber 6. The gas supply pipe 83 is connected to a gas supply source 85. Under the control of the control unit 3, the gas supply source 85 delivers nitrogen or a mixed gas of ammonia and nitrogen as a processing gas to the gas supply pipe 83. In addition, a valve 84 and a flow regulating valve 90 are installed in the middle of the path of the gas supply pipe 83. When the valve 84 is opened, the processing gas is delivered from the gas supply source 85 to the buffer space 82. The flow rate of the processing gas flowing in the gas supply pipe 83 and delivered to the buffer space 82 is adjusted by the flow regulating valve 90. The flow rate of the process gas specified by the flow regulating valve 90 is variable by the control of the control unit 3. The process gas flowing into the buffer space 82 flows in a diffused manner in the buffer space 82 having a smaller fluid resistance 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 process gas is not limited to nitrogen and ammonia, but may be an inert gas such as argon (Ar) and helium (He) or a reactive gas such as oxygen (O2), hydrogen (H2), chlorine (Cl2), hydrogen chloride (HCl), ozone (O3), nitric oxide (NO), nitrous oxide (N2O), and nitrogen dioxide (NO2).

[0162] On the other hand, a gas discharge hole 86 for discharging the gas in the heat treatment space 65 is provided at the lower part of the inner wall of the chamber 6. The gas discharge hole 86 is located at the lower side of the recess 62 and may also be provided 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 a circular ring 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 installed in the middle of the path of the gas discharge pipe 88. When 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, the gas supply hole 81 and the gas discharge hole 86 may be provided in a plurality along the circumference of the chamber 6, or may be in a slit shape.

[0163] Figure 81 is a diagram showing the structure of the exhaust section 190. The exhaust section 190 has an exhaust pump 191, a flow regulating valve 196, three bypass paths 197, 198, 199, and three exhaust valves 192, 193, 194. The gas exhaust pipe 88 that guides the exhaust from the chamber 6 and the exhaust pump 191 are connected through the three bypass paths 197, 198, 199. The three bypass paths 197, 198, 199 are arranged side by side. The pipe diameters of the three bypass paths 197, 198, 199 are different from each other. The diameter of the bypass path 197 is the smallest, the diameter of the bypass path 199 is the largest, and the diameter of the bypass path 198 is between the above two. As a result, the flow rate of the gas that can pass through increases in the order of the bypass paths 197, 198, 199.

[0164] The three exhaust valves 192, 193, and 194 are respectively provided in the three bypass paths 197, 198, and 199. That is, the exhaust valve 192 is installed in the bypass path 197, the exhaust valve 193 is installed in the bypass path 198, and the exhaust valve 194 is installed in the bypass path 199. When the exhaust pump 191 is operated and the three exhaust valves 192, 193, and 194 are opened, the exhaust gas from the chamber 6 guided by the gas exhaust pipe 88 is sucked into the exhaust pump 191 through the corresponding bypass paths 197, 198, and 199.

[0165] Since the pipe diameters of the three bypass paths 197, 198, and 199 are different, the exhaust capacities are different. The larger the pipe diameter, the greater the exhaust capacity, and the exhaust capacity increases in the order of the bypass paths 197, 198, and 199. Therefore, by opening and closing any one of the three exhaust valves 192, 193, and 194, the exhaust flow rate from the chamber 6 can be controlled. Only one of the three exhaust valves 192, 193, and 194 can be opened, or two or three can be opened. For example, when the exhaust valves 193 and 194 are closed and only the exhaust valve 192 is opened, exhaust is performed at the minimum exhaust flow rate. In addition, when all three exhaust valves 192, 193, and 194 are opened, exhaust is performed at the maximum exhaust flow rate.

[0166] In addition, a flow regulating valve 196 is installed between the confluence portion of the three bypass paths 197, 198, and 199 and the exhaust pump 191. The exhaust flow rate of the gas exhaust pipe 88 can also be adjusted by the flow regulating valve 196. The exhaust flow rate specified by the flow regulating valve 196 is variable by the control of the control unit 3. The three bypass paths 197, 198, and 199 are mechanisms for discontinuously and multi-stage adjusting the exhaust flow rate, while the flow regulating valve 196 is a mechanism for continuously and steplessly adjusting the exhaust flow rate.

[0167] The gas supply pipe 83, the gas exhaust pipe 88 and the three bypass paths 197, 198, 199 are made of stainless steel having excellent strength and corrosion resistance. In addition, a pressure gauge 180 for measuring the pressure of the heat treatment space 65 is provided in the chamber 6. Preferably, the measuring range of the pressure gauge 180 is about 5Pa to 0.2MPa.

[0168] Figure 2 2 is a perspective view showing the overall appearance of the holding portion 7. Figure 3 is a top view of the holding portion 7 as viewed from above, Figure 4 7 is a side view of the holding part 7. The holding part 7 has a base ring 71, a connecting part 72, and a base 74. The base ring 71, the connecting part 72, and the base 74 are all formed of quartz. That is, the entire holding part 7 is formed of quartz.

[0169] The base ring 71 is a ring-shaped quartz member. The base ring 71 is supported by the wall surface of the chamber 6 by being placed on the bottom surface of the recess 62 (see Figure 1 ). A plurality of connection parts 72 (four in this embodiment) are provided along the circumferential direction on the upper surface of the base ring 71 having an annular shape. The connection part 72 is also a quartz component and is fixed to the base ring 71 by welding. In addition, the shape of the base ring 71 can also be an arc shape with a portion cut off from the annular shape.

[0170] The flat plate-shaped base 74 is supported by four connecting parts 72 provided on the base ring 71. The base 74 is a roughly circular flat plate-shaped member formed of quartz. The diameter of the base 74 is larger than the diameter of the semiconductor wafer W. That is, the base 74 has a larger plane size than the semiconductor wafer W. A plurality of (five in this embodiment) guide pins 76 are vertically provided on the upper surface of the base 74. The five guide pins 76 are arranged along a circumference concentric with the outer circumference of the base 74. The diameter of the circle on which the five guide pins 76 are arranged is slightly larger than the diameter of the semiconductor wafer W. Each guide pin 76 is also formed of quartz. In addition, the guide pin 76 can be processed from a quartz block as a whole with the base 74, or a separately processed member can be mounted on the base 74 by welding or the like.

[0171] The four connecting parts 72 erected on the base ring 71 are fixed to the lower surface of the peripheral part of the base 74 by welding. That is, the base 74 and the base ring 71 are fixedly connected by the connecting parts 72, and the holding part 7 is an integrally formed component of quartz. The base ring 71 of such a holding part 7 is supported by the wall surface of the chamber 6, and the holding part 7 is installed in the chamber 6. When the holding part 7 is installed in the chamber 6, the base 74 of the substantially circular plate shape is in a horizontal posture (a posture in which the normal line is consistent with the vertical direction). The semiconductor wafer W moved into the chamber 6 is placed in a horizontal posture on the base 74 of the holding part 7 installed in the chamber 6. The semiconductor wafer W is placed on the inner side of the circle formed by the five guide pins 76, which can prevent the position deviation in the horizontal direction. In addition, the number of guide pins 76 is not limited to five, as long as it is a number that can prevent the position deviation of the semiconductor wafer W.

[0172] In addition, if Figure 2 as well as Figure 3 As shown, an opening 78 and a notch 77 are formed on the base 74 so as to penetrate from top to bottom. The notch 77 is provided for the tip of the probe of the contact thermometer 130 using a thermocouple to pass through. On the other hand, the opening 78 is provided for the radiation thermometer 120 to receive the radiation light (infrared light) radiated from the lower surface of the semiconductor wafer W held by the base 74. In addition, four through holes 79 are provided through the base 74, and the through holes 79 are used for the lifting pins 12 of the transfer mechanism 10 described later to penetrate and transfer the semiconductor wafer W.

[0173] 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 has two transfer arms 11. The transfer arms 11 are roughly in an arc shape along the annular recess 62. Two lifting pins 12 are vertically provided on each transfer arm 11. Each transfer arm 11 can be rotated by a horizontal moving mechanism 13. The horizontal moving mechanism 13 can move a pair of transfer arms 11 in a transfer operation position ( Figure 5 The solid line position) and the retreat position ( Figure 5 As the horizontal moving mechanism 13, each transfer arm 11 can be rotated separately by different motors, or a link mechanism can be used to rotate a pair of transfer arms 11 in conjunction with one motor.

[0174] 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 lifting pins 12 pass through the through holes 79 (see Figure 2, 3 ), and the upper ends of the lifting pins 12 protrude from the upper surface of the base 74. On the other hand, when the lifting mechanism 14 lowers the pair of transfer arms 11 in the transfer action position, the lifting pins 12 are pulled out from the through holes 79, and the horizontal movement mechanism 13 moves the pair of transfer arms 11 in an open manner, each transfer arm 11 moves to the retracted position. The retracted position of the pair of transfer arms 11 is directly above the base ring 71 of the holding portion 7. Since the base ring 71 is placed on the bottom surface of the recessed portion 62, the retracted position of the transfer arm 11 is located inside the recessed portion 62.

[0175] Back to Figure 1 The flash heating unit 5 disposed above the chamber 6 has a light source composed of a plurality of (30 in this embodiment) xenon flash lamps FL and a reflector 52 disposed so as to cover the upper part of the light source inside a frame 51. In addition, a light radiation window 53 is installed at the bottom of the frame 51 of the flash heating unit 5. The light radiation window 53 constituting the bottom 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 opposite to the upper chamber window 63. The flash lamp FL irradiates flash light from above the chamber 6 through the light radiation window 53 and the upper chamber window 63 to the heat treatment space 65.

[0176] The flash lamps FL are long cylindrical rod-shaped lamps arranged in a plane so that their length directions are parallel to each other along the main surface (i.e., in the horizontal direction) of the semiconductor wafer W held by the holding portion 7. Therefore, the plane formed by the arrangement of the flash lamps FL is also a horizontal plane.

[0177] The xenon flash lamp FL has a rod-shaped 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 additionally provided on the outer peripheral surface of the glass tube. Since the xenon gas is electrically an insulator, even if a charge is stored in the capacitor, under normal conditions, no current flows in the glass tube. However, when a high voltage is applied to the trigger electrode to break the insulation, the current stored in the capacitor flows in the glass tube instantaneously, and light is emitted due to the excitation of the atoms or molecules of the xenon gas at this time. In such a 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 continuously lit light source such as a halogen lamp HL. That is, the flash lamp FL is a pulse light lamp that emits light instantaneously in an extremely short time of less than 1 second. In addition, the light emission time of the flash lamp FL can be adjusted according to the coil constant of the lamp power supply that supplies power to the flash lamp FL.

[0178] In addition, the reflector 52 is provided above the plurality of flash lamps FL so as to cover the entire plurality of flash lamps FL. 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.

[0179] The halogen heating unit 4 provided below the chamber 6 has a plurality of (40 in this embodiment) halogen lamps HL built inside a frame 41. The halogen heating unit 4 is a light irradiation unit that heats the semiconductor wafer W by irradiating light from the bottom of the chamber 6 through the lower chamber window 64 into the heat treatment space 65 using the plurality of halogen lamps HL.

[0180] Figure 7 It is a top view showing the configuration of a plurality of halogen lamps HL. 40 halogen lamps HL are divided into two layers, upper and lower. 20 halogen lamps HL are configured in the upper layer close to the holding portion 7, and 20 halogen lamps HL are also configured in the lower layer which is farther from the holding portion 7 than the upper layer. Each halogen lamp HL is a rod-shaped lamp with a long cylindrical shape. In the upper layer and the lower layer, the 20 halogen lamps HL are arranged so that their respective length directions are parallel to each other along the main surface of the semiconductor wafer W held by the holding portion 7 (i.e., along the horizontal direction). As a result, in the upper layer and the lower layer, the planes formed by the arrangement of the halogen lamps HL are all horizontal planes.

[0181] In addition, if Figure 7 As shown in the figure, in the upper and lower layers, the halogen lamps HL are arranged at a higher density in the area facing the peripheral portion than in the area facing the central portion of the semiconductor wafer W held by the holding portion 7. That is, in the upper and lower layers, the arrangement spacing of the halogen lamps HL in the peripheral portion is shorter than in the central portion of the lamp arrangement. Therefore, when the halogen heating unit 4 irradiates light for heating, a larger amount of light can be irradiated to the peripheral portion of the semiconductor wafer W where the temperature drop is likely to occur.

[0182] 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 crosswise in a lattice shape, that is, a total of 40 halogen lamps HL are arranged in such a way that the length directions of the 20 halogen lamps HL arranged in the upper layer and the length directions of the 20 halogen lamps HL arranged in the lower layer are perpendicular to each other.

[0183] The halogen lamp HL is a filament-type light source that turns the filament incandescent and emits light by energizing the filament disposed inside a glass tube. A gas formed by introducing a trace amount of halogen elements (iodine, bromine, etc.) into an inert gas such as nitrogen or argon is sealed inside the glass tube. 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 longer life and the ability to continuously irradiate strong light compared to a conventional incandescent lamp. That is, the halogen lamp HL is a continuously lit lamp that emits light continuously for at least 1 second. In addition, since the halogen lamp HL is a rod-shaped lamp, it has a long life, and by arranging the halogen lamp HL in the horizontal direction, the efficiency of radiating to the semiconductor wafer W above is excellent.

[0184] In addition, 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.

[0185] The control unit 3 controls the above-mentioned 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 has a circuit for performing various calculations, namely a CPU, a dedicated read memory for storing basic programs, namely a ROM, a freely readable and writable memory for storing various information, namely a RAM, and a disk for storing control software and data. The processing in the heat treatment device 1 is performed by executing a prescribed processing program through the CPU of the control unit 3. In addition, the control unit 3 controls valve 84, valve 89, flow regulating valve 90, flow regulating valve 196, exhaust pump 191 and three exhaust valves 192, 193, and 194 to adjust the pressure, gas supply flow rate, and exhaust rate of the heat treatment space 65 in the chamber 6.

[0186] In addition to the above-mentioned structures, the heat treatment device 1 also has various cooling structures to prevent the temperature of the halogen heating unit 4, the flash heating unit 5 and the chamber 6 from excessively rising due to the heat energy generated by the halogen lamp HL and the flash lamp FL when the semiconductor wafer W is heat treated. 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 air-cooled structures that form a gas flow inside to discharge heat. In addition, air is supplied to the gap between the upper chamber window 63 and the lamp radiation window 53 to cool the flash heating unit 5 and the upper chamber window 63.

[0187] Next, the processing sequence of the semiconductor wafer W in the heat treatment apparatus 1 is described. Here, the semiconductor wafer W to be processed is a semiconductor substrate on which a high dielectric constant film as a gate insulating film is formed. The semiconductor wafer W is irradiated with a flash in an ammonia gas atmosphere by the heat treatment apparatus 1 to perform a post-film formation thermal treatment (PDA) to eliminate defects in the high dielectric constant film and perform a nitridation treatment.

[0188] Fig. 9 1 is a diagram showing a stacked structure in which a high dielectric constant film is formed on a semiconductor wafer W. A silicon dioxide film (SiO2) 102 is formed on a silicon substrate 101 of the semiconductor wafer W. The silicon dioxide film 102 is a layer required as an interface layer film between the silicon substrate 101 and the high dielectric constant film 103. The film thickness of the silicon dioxide film 102 is extremely thin, for example, about 1 nm. As a method for forming the silicon dioxide film 102, various known methods such as a thermal oxidation method can be used.

[0189] Furthermore, a high dielectric constant film 103 is formed on the silicon dioxide film 102 as a gate insulating film. As the high dielectric constant film 103, a high dielectric constant material such as HfO2, ZrO2, Al2O3, La2O3 (HfO2 in the present embodiment) can be used. The high dielectric constant film 103 is formed by depositing a high dielectric constant material on the silicon dioxide film 102 using, for example, atomic layer deposition (ALD: Atomic Layer Deposition). The film thickness of the high dielectric constant film 103 deposited on the silicon dioxide film 102 is several nm, but the equivalent film thickness (EOT: Equivalent oxide thickness) of the silicon dioxide film is about 1 nm. The formation method of the high dielectric constant film 103 is not limited to ALD, and a well-known method such as metal organic chemical vapor deposition (MOCVD: Metal Organic Chemical Vapor Deposition) can also be used. Regardless of the method, in the deposited state, there are defects such as a plurality of point defects in the high dielectric constant film 103 that has not been specially treated. Fig. 9 In the structure shown, SiN sidewalls 104 are formed on both sides of the high dielectric constant film 103, but the sidewalls 104 are formed before the high dielectric constant film 103 in, for example, a gate-last process. In addition, after the heat treatment using the heat treatment apparatus 1 is completed, titanium (Ti) or titanium nitride (TiN) is deposited on the high dielectric constant film 103 to serve as a metal gate.

[0190] Through the heat treatment device 1 Fig. 9A semiconductor wafer W having a high dielectric constant film 103 formed on a silicon substrate 101 via a silicon dioxide film 102 is subjected to heat treatment. Next, the operation sequence in the heat treatment apparatus 1 is described. The operation sequence in the heat treatment apparatus 1 is performed by the control unit 3 controlling each operation mechanism of the heat treatment apparatus 1.

[0191] First, a semiconductor wafer W having a high dielectric constant film 103 formed on a silicon dioxide film 102 which is an interface layer film is carried into the chamber 6 of the heat treatment apparatus 1. When the semiconductor wafer W is carried in, the gate valve 185 is opened to open the transport opening 66, and the semiconductor wafer W having the high dielectric constant film 103 formed thereon is carried into the heat treatment space 65 in the chamber 6 through the transport opening 66 by a transport robot outside the apparatus. At this time, since both the inside and outside of the chamber 6 are at atmospheric pressure, air is brought into the heat treatment space 65 in the chamber 6 as the semiconductor wafer W is carried in. Therefore, by opening the valve 84 and continuously supplying nitrogen gas from the gas supply source 85 into the chamber 6, the nitrogen gas flow is made to flow out from the transport opening 66, thereby limiting the gas outside the apparatus that flows into the chamber 6 to a minimum. In addition, when the gate valve 185 is opened, it is preferred that the supply flow rate of nitrogen gas is increased compared to the heat treatment of the semiconductor wafer W (for example, if it is usually 30 L / min during the heat treatment, it becomes 120 L / min when the gate valve 185 is opened). Furthermore, it is preferred that the supply flow rate of nitrogen gas is increased and the valve 89 is closed to stop the exhaust from the chamber 6. Thus, since the nitrogen gas supplied to the chamber 6 flows out only from the transfer opening 66, the inflow of external air can be more effectively prevented.

[0192] The semiconductor wafer W carried in by the transfer robot enters and stops at a position just above the holding portion 7. Then, the pair of transfer arms 11 of the transfer mechanism 10 horizontally move from the retracted position to the transfer operation position and rise, whereby the lift pins 12 protrude from the upper surface of the base 74 through the through holes 79 to receive the semiconductor wafer W.

[0193] After the semiconductor wafer W is placed on the lifting pins 12, the transport robot withdraws from the heat treatment space 65 and closes the transport opening 66 by the gate valve 185. Then, by lowering the pair of transfer arms 11, the semiconductor wafer W is transferred from the transfer mechanism 10 to the base 74 of the holding portion 7 and is held in a horizontal posture. The semiconductor wafer W is held by the base 74 with the surface on which the high dielectric constant film 103 is formed as the upper surface. In addition, the semiconductor wafer W is held on the inner side of the five guide pins 76 on the upper surface of the base 74. The pair of transfer arms 11 that have been lowered to the bottom of the base 74 are retracted to the retracted position, i.e., the inner side of the recess 62, by the horizontal moving mechanism 13.

[0194] After the semiconductor wafer W is accommodated in the chamber 6 and the transfer opening 66 is closed by the gate valve 185, the pressure in the chamber 6 is reduced to a pressure lower than the atmospheric pressure. Specifically, by closing the transfer opening 66, the heat treatment space 65 in the chamber 6 becomes a closed space. In this state, the valve 84 for gas supply is closed, and the valve 89 for exhaust is opened. In addition, the control unit 3 activates the exhaust pump 191 and opens the exhaust valve 192 provided on the bypass path 197 with the smallest pipe diameter among the three bypass paths 197, 198, and 199. The other exhaust valves 193 and 194 are closed. As a result, the chamber 6 is not supplied with gas but exhausted, so that the heat treatment space 65 in the chamber 6 is depressurized.

[0195] Fig.10 It is a diagram showing the pressure change in the chamber 6 in the first embodiment. Fig.10 The horizontal axis represents time, and the vertical axis represents the pressure in the chamber 6. At the time when the semiconductor wafer W is accommodated in the chamber 6 and the transfer opening 66 is closed, the pressure in the chamber 6 is normal pressure Ps (= atmospheric pressure = about 101325 Pa). And at time t1, the pressure reduction in the chamber 6 begins. In the initial stage of the pressure reduction, since only the bypass path 197 with the smallest pipe diameter among the three bypass paths 197, 198, and 199 is used, the exhaust flow rate is small and the exhaust speed is also relatively slow.

[0196] Next, at time t2, the control unit 3 opens all three exhaust valves 192, 193, and 194. As a result, the exhaust flow rate from the chamber 6 increases and the exhaust speed also becomes faster. Furthermore, at time t3, the pressure (vacuum degree) of the chamber 6 reaches the air pressure P1. The air pressure P1 is, for example, about 100 Pa. That is, after exhausting at a small exhaust flow rate in the initial stage of decompression, exhaust is switched to an exhaust flow rate larger than the above-mentioned small exhaust volume for exhaust. In addition, in the first embodiment, the flow rate of the flow regulating valve 196 is constant.

[0197] If exhaust is performed quickly at a large exhaust flow rate from the beginning of decompression, there may be a problem that a large change in airflow occurs in the chamber 6, and particles attached to the structure of the chamber 6 (for example, the lower chamber window 64) are rolled up and re-attached to the semiconductor wafer W, thereby causing contamination. If exhaust is performed quietly at a small exhaust flow rate in the initial stage of decompression and then switched to a large exhaust flow rate for exhaust, the above-mentioned rolling up of particles in the chamber 6 can be prevented.

[0198] In addition, exhaust part 190 has the harm-eliminating device (omitted diagram) that makes reactive gases such as ammonia harmless, but, if just exhaust with big exhaust flow when beginning decompression, then a large amount of gas flows into this harm-eliminating device and may make this harm-eliminating device overload.As described in present embodiment, if exhaust with little exhaust flow after in the initial stage of decompression, switch to big exhaust flow and exhaust, then can prevent the harm-eliminating device from overloading.In addition, after the pressure reduction to a certain degree in the chamber 6, even exhaust with big exhaust flow, the gas amount that flows into exhaust part 190 is also less.

[0199] At time t3 when the pressure in the chamber 6 reaches the gas pressure P1, the valve 89 for exhaust is closed and the valve 84 for gas supply is opened, and a mixed gas of ammonia and nitrogen as a dilution gas is supplied from the gas supply source 85 to the heat treatment space 65 in the chamber 6. As a result, in the chamber 6, an ammonia gas environment is formed around the semiconductor wafer W held by the holding portion 7. The concentration of ammonia in the ammonia gas environment (i.e., the mixing ratio of ammonia and nitrogen) is not particularly limited and can be set to a suitable value, but it can be, for example, less than 10 vol.% (about 2.5 vol.% in this embodiment). In addition, it is also possible to exhaust from the chamber 6 using only the bypass path 197 with the smallest pipe diameter during the supply of the mixed gas of ammonia and nitrogen to the chamber 6. In this case, of course, the supply flow rate of the mixed gas is larger than the exhaust flow rate.

[0200] By supplying the mixed gas into the chamber 6, the pressure in the chamber 6 rises from the gas pressure P1 and returns to the normal pressure Ps at time t4. In the first embodiment, since the pressure in the chamber 6 is restored to the normal pressure Ps once it is reduced to the gas pressure P1, the oxygen concentration in the gas atmosphere of the ammonia gas in the chamber 6 after the pressure is restored to the normal pressure Ps can be set to about 200 ppb.

[0201] After time t4 when the pressure in the chamber 6 returns to normal pressure Ps, the supply flow rate of the mixed gas of ammonia and nitrogen to the chamber 6 and the exhaust flow rate from the chamber 6 become equal, thereby maintaining the pressure in the chamber 6 at normal pressure Ps.

[0202] In addition, at time t4 when the pressure in the chamber 6 returns to the normal pressure Ps, the 40 halogen lamps HL of the halogen heating unit 4 are all lit to start the preliminary heating (auxiliary heating) of the semiconductor wafer W. The halogen light emitted from the halogen lamp HL passes through the lower chamber window 64 and the base 74 formed of quartz, and irradiates the back side of the semiconductor wafer W. The back side of the semiconductor wafer W is the main surface on the opposite side to the surface on which the high dielectric constant film 103 is formed. The temperature of the semiconductor wafer W rises by receiving the light irradiation from the halogen lamp HL. In addition, since the transfer arm 11 of the transfer mechanism 10 retreats to the inner side of the recess 62, the heating of the halogen lamp HL is not hindered.

[0203] When the halogen lamp HL is used for preheating, the temperature of the semiconductor wafer W is measured by the contact thermometer 130. That is, the contact thermometer 130 with a built-in thermocouple contacts the lower surface of the semiconductor wafer W held by the susceptor 74 via the cutout portion 77 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 controls the output of the halogen lamp HL while monitoring whether the temperature of the semiconductor wafer W heated by the light irradiation from the halogen lamp HL has reached the prescribed preheating temperature T1. That is, the control unit 3 performs feedback control on the output of the halogen lamp HL based on the measured value of the contact thermometer 130 so that the temperature of the semiconductor wafer W becomes the preheating temperature T1. The preheating temperature T1 is 300°C to 600°C, and is 450°C in the present embodiment. In addition, when the temperature of the semiconductor wafer W is heated by the light irradiation from the halogen lamp HL, the temperature is not measured by the radiation thermometer 120. This is because the halogen light emitted from the halogen lamp HL enters the radiation thermometer 120 as disturbance light, and accurate temperature measurement cannot be performed.

[0204] 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 contact thermometer 130 reaches the preheating temperature T1, 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 T1.

[0205] By performing preliminary heating using such a halogen lamp HL, the entire semiconductor wafer W including the high dielectric constant film 103 is uniformly heated to the preliminary heating temperature T1. In the preliminary heating stage using 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. However, the density of the halogen lamps HL in the halogen heating unit 4 is higher in the area corresponding to the peripheral portion than in the area corresponding to 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 more, and the in-plane temperature distribution of the semiconductor wafer W in the preliminary heating stage can be made uniform. In addition, since the inner peripheral surface of the reflection ring 69 installed on the side portion 61 of the chamber is a mirror surface, the amount of light reflected by the inner peripheral surface of the reflection ring 69 to the peripheral portion of the semiconductor wafer W becomes more, so that the in-plane temperature distribution of the semiconductor wafer W in the preliminary heating stage can be made uniform. In addition, the pressure in the chamber 6 during the preliminary heating is maintained at a normal pressure Ps.

[0206] Next, at time t5 when the temperature of the semiconductor wafer W reaches the preheating temperature T1 and a predetermined time has passed, a flash heating process is performed by irradiating a flash from the flash lamp FL. At this time, a part of the flash radiated from the flash lamp FL is directly irradiated into the chamber 6, and the other part is once reflected by the reflector 52 and then irradiated into the chamber 6. By the irradiation of the above-mentioned flash, the semiconductor wafer W is flash heated.

[0207] Flash heating is performed by flash irradiation from a flash lamp FL, so the surface temperature of the semiconductor wafer W can be increased in a short time. That is, the flash irradiated from the flash lamp FL is an extremely short strong flash of about 0.1 milliseconds to 100 milliseconds, which converts the electrostatic energy previously stored in the capacitor into an extremely short light pulse. The flash irradiation from the flash lamp FL is an extremely short strong flash of about 0.1 milliseconds to 100 milliseconds. By irradiating the surface of the semiconductor wafer W having the high dielectric constant film 103 formed on the substrate 101 via the silicon dioxide film 102 with a flash, the surface of the semiconductor wafer W including the high dielectric constant film 103 is instantly heated to the processing temperature T2, and a post-film formation heat treatment is performed. The highest temperature (peak temperature) reached by the surface of the semiconductor wafer W due to the flash irradiation, that is, the processing temperature T2, is 600°C to 1200°C, and is 1000°C in the present embodiment.

[0208] If the surface temperature of the semiconductor wafer W is raised to the processing temperature T2 in the ammonia gas atmosphere to perform the post-film formation heat treatment, the nitridation of the high dielectric constant film 103 can be promoted, and defects such as point defects existing in the high dielectric constant film 103 can be eliminated. In addition, since the irradiation time of the flash lamp FL is a short time of about 0.1 milliseconds to 100 milliseconds, the time required for the surface temperature of the semiconductor wafer W to rise from the preheating temperature T1 to the processing temperature T2 is also an extremely short time of less than 1 second. The surface temperature of the semiconductor wafer W after the flash irradiation immediately drops rapidly from the processing temperature T2.

[0209] After the flash heating process is completed, the valve 84 for supplying air is closed to reduce the pressure in the chamber 6 again. The pattern of the decompression at this time is the same as the pattern of the decompression from the time t1 to the time t3 described above. That is, in the initial stage of decompression, only the bypass path 197 with the smallest pipe diameter among the three bypass paths 197, 198, and 199 is used, so that the exhaust flow rate is relatively small. Then, all three exhaust valves 192, 193, and 194 are opened to increase the exhaust flow rate. That is, after exhausting at a small exhaust flow rate in the initial stage of decompression, the exhaust is switched to an exhaust flow rate larger than the small exhaust flow rate described above. The reason for switching the exhaust flow rate to two levels for exhaust is the same as described above.

[0210] By reducing the pressure in the chamber 6 to the pressure P1 again, harmful ammonia can be discharged from the heat treatment space 65 in the chamber 6. Next, the valve 89 for exhaust is closed and the valve 84 for gas supply is opened, and nitrogen is supplied from the gas supply source 85 into the chamber 6 to restore to normal pressure Ps. The supply flow rate of nitrogen at this time is 50L / min or more. In addition, the halogen lamp HL is also turned off, thereby the semiconductor wafer W is also cooled from the preheating temperature T1. The temperature of the semiconductor wafer W during cooling is measured by the contact thermometer 130 or the radiation thermometer 120, and the measurement result is transmitted to the control unit 3. Based on the measurement result, the control unit 3 monitors whether the temperature of the semiconductor wafer W has been cooled to a specified temperature. In addition, after the temperature of the semiconductor wafer W is cooled to below the specified 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, thereby, the lifting pins 12 protrude from the upper surface of the base 74, and the semiconductor wafer W after heat treatment is received from the base 74. Next, the transfer opening 66 closed by the gate valve 185 is opened, and the semiconductor wafer W placed on the lift pins 12 is carried out by a transfer robot outside the apparatus, thereby completing the heating process of the semiconductor wafer W in the heat treatment apparatus 1 .

[0211] In the first embodiment, since the pressure in the chamber 6 is once reduced to a pressure P1 lower than the atmospheric pressure, a mixed gas of ammonia and nitrogen is supplied to restore to normal pressure Ps, the oxygen concentration in the chamber 6 after the pressure is restored can be reduced to about 200 ppb or less. In the case where the pressure in the chamber 6 is not reduced and the gas atmosphere is replaced from the atmosphere to the mixed gas of ammonia and nitrogen while maintaining the normal pressure, the limit of reducing the oxygen concentration in the chamber 6 is about 2 ppm. That is, as shown in this embodiment, by reducing the pressure in the chamber 6 to the pressure P1 and then restoring to the normal pressure Ps, the oxygen concentration in the chamber 6 can be reduced to about one tenth compared with the case where the pressure is not reduced.

[0212] As described above, since there are multiple point defects and other defects in the high dielectric constant film 103 that has not been specially treated in the deposited state, it is necessary to eliminate such defects through post-film formation heat treatment (PDA). When performing post-film formation heat treatment, if there is oxygen, the silicon dioxide film 102 of the base layer of the high dielectric constant film 103 will absorb the oxygen and grow, thereby increasing the film thickness, and therefore, a high dielectric constant cannot be obtained. As a cause of such an increase in film thickness, the main problem is the oxygen remaining in the chamber 6. As shown in this embodiment, when the semiconductor wafer W is moved into the chamber 6 at normal pressure, the amount of air brought in from the outside becomes larger, thereby increasing the residual oxygen concentration in the chamber 6. Therefore, it is preferred that the oxygen concentration in the gas environment when performing post-film formation heat treatment of the high dielectric constant film 103 is reduced as much as possible. In particular, in the formation of high dielectric constant gate insulating films in recent years, it is required to reduce the oxygen concentration to less than 1ppm.

[0213] In the first embodiment, the pressure in the chamber 6 is once reduced to a pressure P1 lower than the atmospheric pressure and then restored to the normal pressure Ps, so that the oxygen concentration in the heat treatment space 65 in the chamber 6 can be reduced to about 200 ppb or less when performing the post-film formation heat treatment of the high dielectric constant film 103. Therefore, it is possible to suppress the silicon dioxide film 102, which is the base layer of the high dielectric constant film 103, from absorbing oxygen from the heat treatment space 65 during the post-film formation heat treatment and increasing the film thickness.

[0214] In addition, the deposited high dielectric constant film 103 also contains oxygen, and if the processing time of the post-film formation heat treatment is more than several seconds, the diffusion of oxygen will also increase the film thickness of the silicon dioxide film 102. In the first embodiment, since the light is irradiated from the flash lamp FL to the surface of the semiconductor wafer W for less than 1 second, the surface of the wafer is heated to the processing temperature T2 in a very short time, and the processing time of the post-film formation heat treatment is very short and the oxygen does not have enough time to diffuse, the film thickness of the silicon dioxide film 102 at the base of the high dielectric constant film 103 can be suppressed from increasing.

[0215] In the first embodiment, a mixed gas of ammonia and nitrogen is introduced when the pressure in the chamber 6 is restored, and a flash is irradiated from the flash lamp FL to the surface of the semiconductor wafer W in the ammonia gas atmosphere to perform a post-film formation heat treatment. By heating the high dielectric constant film 103 to the treatment temperature T2 in the ammonia gas atmosphere, the high dielectric constant film 103 can be nitrided, and defects existing in the deposited high dielectric constant film 103 can be reduced, thereby suppressing leakage current caused by such defects.

[0216] In addition, by performing flash heating in an ammonia gas atmosphere, the silicon dioxide film 102 of the base layer can also be nitrided. By nitriding the silicon dioxide film 102, the increase in film thickness caused by oxidation of the silicon dioxide film 102 can be more effectively suppressed. In addition, the nitridation of the silicon dioxide film 102 slightly increases the dielectric constant of the silicon dioxide film 102. Thus, the increase in the physical film thickness of the silicon dioxide film 102 can be suppressed, and the electrical film thickness can be reduced. In addition, since the flash irradiation time is an extremely short time of less than 1 second, even if the silicon dioxide film 102 is nitrided, it is possible to suppress the diffusion of nitrogen to the channel side.

[0217] In addition, as described above, when the chamber 6 is depressurized, exhaust is performed at a small exhaust flow rate at the beginning of the depressurization, and then the exhaust is switched to a large exhaust flow rate. Therefore, the particles in the chamber 6 can be prevented from being rolled up, and the harm removal device of the exhaust section 190 can also be prevented from being overloaded.

[0218] <Second Embodiment>

[0219] Next, the second embodiment of the present invention is described. The structure of the heat treatment apparatus 1 of the second embodiment is exactly the same as that of the first embodiment. In addition, the processing sequence of the semiconductor wafer W in the heat treatment apparatus 1 of the second embodiment is also substantially the same as that of the first embodiment. The difference between the second embodiment and the first embodiment is that once the pressure in the chamber 6 is reduced, the pressure is restored.

[0220] Fig.11 : is a diagram showing the pressure change in the chamber 6 in the second embodiment. Fig.11 In, with Fig.10 Similarly, the horizontal axis represents time, and the vertical axis represents the pressure in the chamber 6. Fig.11 The pattern shown by the dotted line in the figure is a pressure change pattern when the pressure in the chamber 6 in the first embodiment is restored to the normal pressure Ps ( Fig.10 pattern).

[0221] As in the first embodiment, when the semiconductor wafer W formed with the high dielectric constant film 103 is contained in the chamber 6 and the transfer opening 66 is closed, the pressure in the chamber 6 is the normal pressure Ps (= atmospheric pressure = about 101325Pa). And, at time t1, the decompression in the chamber 6 begins. As in the first embodiment, after exhausting at a small exhaust flow rate in the initial stage of decompression, at time t2, the exhaust is switched to an exhaust flow rate larger than the above-mentioned small exhaust flow rate for exhaust. Thus, the particles in the chamber 6 can be prevented from rolling up, and the detoxification device of the exhaust unit 190 can be prevented from being overloaded.

[0222] At time t3 when the pressure in the chamber 6 reaches the gas pressure P1, the exhaust valve 89 is closed and the gas supply valve 84 is opened, and a mixed gas of ammonia gas and nitrogen gas as a diluent gas is supplied from the gas supply source 85 to the heat treatment space 65 in the chamber 6. So far, it is the same as the first embodiment. In addition, the gas pressure P1 is, for example, about 100 Pa.

[0223] In the second embodiment, the pressure in the chamber 6 is not restored to the normal pressure Ps, but the mixed gas is supplied to restore the pressure in the chamber 6 to the pressure P2 at time t6. The pressure P2 is higher than the pressure P1 and lower than the normal pressure Ps, and is, for example, about 5000 Pa. In the second embodiment, since the pressure in the chamber 6 is restored to the pressure P2 higher than the pressure P1 after being reduced to the pressure P1, the oxygen concentration in the chamber 6 after the pressure is restored can be reduced to about 200 ppb or less.

[0224] After time t6 when the pressure in the chamber 6 is restored to the pressure P2, the supply flow rate of the mixed gas of ammonia gas and nitrogen gas supplied to the chamber 6 and the exhaust flow rate from the chamber 6 are equal, so that the pressure in the chamber 6 is maintained at the pressure P2. And, while the pressure in the chamber 6 is maintained at the pressure P2, the semiconductor wafer W is preheated by the halogen lamp HL, and then, at time t7, the surface of the semiconductor wafer W is flash-heated by irradiating a flash from the flash lamp FL. The contents of the preheating and flash-heating treatment are the same as those in the first embodiment. The post-film formation heat treatment of the high dielectric constant film 103 is performed by raising the surface of the semiconductor wafer W to the treatment temperature T2 by flash irradiation in the gas atmosphere of ammonia gas.

[0225] After the flash heating process is completed, the valve 84 for gas supply is closed and the pressure in the chamber 6 is reduced to the gas pressure P1 again, thereby exhausting harmful ammonia gas from the heat treatment space 65 in the chamber 6. Next, the valve 89 for exhaust is closed and the valve 84 for gas supply is opened, and nitrogen gas is supplied from the gas supply source 85 into the chamber 6 to restore the pressure to normal pressure Ps. In addition, the halogen lamp HL is also turned off, thereby also cooling the semiconductor wafer W from the preheating temperature T1. Then, the order of carrying out the semiconductor wafer W cooled to the predetermined temperature from the chamber 6 of the heat treatment apparatus 1 is the same as that of the first embodiment.

[0226] In the second embodiment, once the pressure in the chamber 6 is reduced to the pressure P1 lower than the atmospheric pressure, a mixed gas of ammonia and nitrogen is supplied to restore the pressure to the pressure P2. Therefore, as in the first embodiment, the oxygen concentration in the heat treatment space 65 in the chamber 6 can be reduced to about 200 ppb or less when performing the post-film formation heat treatment of the high dielectric constant film 103. Therefore, it is possible to suppress the silicon dioxide film 102, which is the base layer of the high dielectric constant film 103, from absorbing oxygen from the heat treatment space 65 during the post-film formation heat treatment and increasing the film thickness.

[0227] In addition, similar to the first embodiment, since the flash lamp FL irradiates the surface of the semiconductor chip W with a flash light for less than 1 second, the surface of the chip is heated to the processing temperature T2 in a very short time, and the processing time of the heat treatment after film formation is extremely short and there is not enough time for oxygen to diffuse, it is possible to suppress the increase in the film thickness of the silicon dioxide film 102 at the base layer of the high dielectric constant film 103.

[0228] In addition, in the second embodiment, the pressure in the chamber 6 is a gas pressure P2 lower than the atmospheric pressure, that is, under reduced pressure, and a flash is irradiated onto the surface of the semiconductor wafer W to perform a post-film formation heat treatment of the high dielectric constant film 103. Under reduced pressure, since the density of gas molecules is small, the mean free path becomes longer. As a result, if the post-film formation heat treatment of the high dielectric constant film 103 is performed under reduced pressure, since the mean free path of ammonia gas becomes longer, the heat treatment reaction of ammonia gas and the high dielectric constant film 103 can be made uniform. However, if the post-film formation heat treatment of the high dielectric constant film 103 is performed under reduced pressure, as shown in the first embodiment, the partial pressure of ammonia gas itself becomes significantly lower than that of the case where the treatment is performed under normal pressure. Therefore, as shown in the first embodiment, the post-film formation heat treatment of the high dielectric constant film 103 under normal pressure can perform the nitridation treatment of the high dielectric constant film 103 to a greater extent.

[0229] In addition, if the post-film formation heat treatment of the high dielectric constant film 103 is performed under reduced pressure, the removal of impurities (e.g., carbon (C)) contained in the deposited high dielectric constant film 103 can be promoted. By discharging the impurity elements thus removed from the chamber 6, the impurities can be prevented from adhering again to the surface of the semiconductor wafer W and causing contamination. As a result, the degradation of device performance and the reduction of yield can be prevented.

[0230] In addition, since the absorption of halogen light and flash light can be reduced by the gas in the chamber 6, the temperature increase efficiency during preheating and flash heating can be improved. As a result, the surface temperature of the semiconductor wafer W during flash heating can be increased.

[0231] Furthermore, by performing the heat treatment of the semiconductor wafer W under reduced pressure, the influence of convection in the chamber 6 can be reduced, and the uniformity of the in-plane temperature distribution of the semiconductor wafer W can be improved.

[0232] Furthermore, in the second embodiment, when the pressure in the chamber 6 is restored from the air pressure P1, it is not restored to the normal pressure Ps, but to the air pressure P2 which is lower than the atmospheric pressure. Therefore, compared with the case where the pressure in the chamber 6 is restored to the normal pressure Ps as in the first embodiment, if the pressure is restored to the air pressure P2 as shown in the second embodiment, the time required for pressure restoration can be shortened. Furthermore, by shortening the time required for pressure restoration, the timing of flash irradiation can be advanced (e.g., Fig.11 As shown, the flash irradiation time t7 in the second embodiment is earlier than the flash irradiation time t5 in the first embodiment. As a result, as shown in the second embodiment, the pressure in the chamber 6 is restored to the pressure P2 lower than the atmospheric pressure, which can improve the production capacity of the heat treatment device 1.

[0233] <Third Embodiment>

[0234] Next, a third embodiment of the present invention is described. The structure of the heat treatment apparatus 1 of the third embodiment is exactly the same as that of the first embodiment. In addition, the processing sequence of the semiconductor wafer W in the heat treatment apparatus 1 of the third embodiment is also substantially the same as that of the first embodiment. The difference between the third embodiment and the first embodiment is that the pressure in the chamber 6 changes.

[0235] Fig.12 : is a diagram showing the pressure change in the chamber 6 in the third embodiment. Fig.12 In, with Fig.10 Similarly, the horizontal axis represents time, and the vertical axis represents the pressure in the chamber 6 .

[0236] As in the first embodiment, when the semiconductor wafer W formed with the high dielectric constant film 103 is accommodated in the chamber 6 and the transfer opening 66 is closed, the pressure in the chamber 6 is the normal pressure Ps (= atmospheric pressure = about 101325Pa). And, at time t1, the decompression in the chamber 6 begins. In the third embodiment, the exhaust flow rates of the three bypass paths 197, 198, and 199 are set to be constant, and the exhaust flow rate from the chamber 6 is continuously increased over time by using the flow regulating valve 196. That is, exhaust is started at a relatively small exhaust flow rate in the initial stage of decompression, and the exhaust flow rate is gradually increased continuously. In this way, as in the first embodiment, the particles in the chamber 6 can be prevented from rolling up, and the detoxification device of the exhaust section 190 can also be prevented from being overloaded. In addition, by continuously increasing the exhaust flow rate in a stepless manner, the rolling up of particles caused by a sudden change in the exhaust flow rate can be prevented.

[0237] At time t3 when the pressure in the chamber 6 reaches the gas pressure P1, the exhaust valve 89 is closed and the gas supply valve 84 is opened, and a mixed gas of ammonia gas and nitrogen gas as a diluent gas is supplied from the gas supply source 85 to the heat treatment space 65 in the chamber 6 to restore the pressure in the chamber 6. In addition, the gas pressure P1 is, for example, about 100 Pa.

[0238] In the third embodiment, the flow rate of the processing gas supplied to the chamber 6 is continuously increased over time by using the flow rate regulating valve 90. That is, the gas supply is started at a relatively small gas supply rate at the initial stage of restoring the pressure, and the gas supply rate is gradually and continuously increased. Similar to the decompression, if the gas is quickly supplied at a large gas supply rate from the beginning of restoring the pressure, particles attached to the structure of the chamber 6 may be rolled up. By quietly starting the gas supply at a small gas supply rate at the initial stage of restoring the pressure and gradually increasing the exhaust flow rate, the particles in the chamber 6 can be prevented from being rolled up. In addition, by continuously increasing the gas supply rate in a stepless manner, the rolling up of particles caused by a sudden change in the gas supply rate can also be prevented.

[0239] In the third embodiment, the pressure in the chamber 6 is restored to a pressure P3 higher than the normal pressure Ps at time t8 by supplying the mixed gas to the chamber 6. The pressure P3 is higher than the atmospheric pressure, for example, about 0.15 MPa. In the third embodiment, once the pressure in the chamber 6 is reduced to the pressure P1, it is restored to the pressure P3 higher than the pressure P1, so the oxygen concentration in the chamber 6 after the pressure is restored can be reduced to about 200 ppb or less.

[0240] After time t8 when the pressure in the chamber 6 is restored to the pressure P3, the supply flow rate of the mixed gas of ammonia gas and nitrogen gas supplied to the chamber 6 and the exhaust flow rate from the chamber 6 are equal, so that the pressure in the chamber 6 is maintained at the pressure P3. While the pressure in the chamber 6 is maintained at the pressure P3, the semiconductor wafer W is preheated by the halogen lamp HL, and then at time t9, the surface of the semiconductor wafer W is flash-heated by irradiating a flash from the flash lamp FL. The contents of the preheating and flash heating treatment are the same as those of the first embodiment. In the gas atmosphere of ammonia gas, the surface of the semiconductor wafer W is heated by flash irradiation, thereby performing a post-film formation heat treatment of the high dielectric constant film 103.

[0241] After the flash heating process is completed, the valve 84 for gas supply is closed and the pressure in the chamber 6 is reduced to the pressure P1 again, thereby exhausting harmful ammonia gas from the heat treatment space 65 in the chamber 6. At this time, the exhaust flow rate from the chamber 6 is continuously increased over time by the flow regulating valve 196, thereby preventing the particles from being rolled up due to the exhaust.

[0242] Next, the exhaust valve 89 is closed and the gas supply valve 84 is opened, and nitrogen gas is supplied from the gas supply source 85 into the chamber 6 to restore the pressure to normal pressure Ps. At this time, the flow rate of the gas supplied to the chamber 6 is continuously increased over time by the flow rate adjustment valve 90, so that the particles caused by the gas supply can be prevented from rolling up.

[0243] The halogen lamp HL is also turned off, thereby cooling the semiconductor wafer W from the preheating temperature T1. Then, the procedure of unloading the semiconductor wafer W cooled to a predetermined temperature from the chamber 6 of the heat treatment apparatus 1 is the same as that of the first embodiment.

[0244] However, as a main cause of particles rolling up in the chamber 6, in addition to the supply and exhaust of the chamber 6, there is also flash irradiation. When the flash is irradiated from the flash lamp FL, the surface of the semiconductor wafer W is instantly heated up, while the back surface is not heated up from the preliminary heating temperature T1, so a large temperature difference is generated between the surface and the back surface, and thus only the surface is thermally expanded, so that the semiconductor wafer W is rapidly deformed. As a result, particles are generated by the vibration of the semiconductor wafer W on the susceptor 74, and are rolled up in the chamber 6.

[0245] In order to effectively discharge such particles generated by flash irradiation from the chamber 6, in the third embodiment, after the flash heating process is completed and the ammonia gas is discharged, nitrogen gas is supplied into the chamber 6 to restore the pressure to normal pressure Ps, and the nitrogen gas is flowed into the chamber 6 at a flow rate of 50 L / min to 100 L / min, so that the particles generated by flash irradiation can be washed away. In this way, it is possible to prevent the particles generated by flash irradiation from adhering to the semiconductor wafer W and causing contamination.

[0246] Furthermore, when nitrogen is supplied to the chamber 6 after the ammonia is exhausted to restore the pressure to normal pressure Ps, the valve 84 for supplying gas may be opened while the valve 89 for exhaust is opened to supply nitrogen to the chamber 6. In this way, particles generated by flash irradiation can be exhausted from the chamber 6 more effectively.

[0247] In the third embodiment, once the pressure in the chamber 6 is reduced to the pressure P1 lower than the atmospheric pressure, a mixed gas of ammonia and nitrogen is supplied to restore the pressure to the pressure P3. Therefore, as in the first embodiment, the oxygen concentration in the heat treatment space 65 in the chamber 6 can be reduced to about 200 ppb or less when performing the post-film formation heat treatment of the high dielectric constant film 103. Therefore, it is possible to suppress the silicon dioxide film 102, which is the base layer of the high dielectric constant film 103, from absorbing oxygen from the heat treatment space 65 during the post-film formation heat treatment and increasing the film thickness.

[0248] In addition, similar to the first embodiment, since the flash lamp FL irradiates the surface of the semiconductor chip W with a flash for less than 1 second, the surface of the chip is heated in an extremely short time, and the processing time of the heat treatment after film formation is extremely short and the oxygen does not have sufficient diffusion time, it is possible to suppress the increase in the film thickness of the silicon dioxide film 102 at the base layer of the high dielectric constant film 103.

[0249] In the third embodiment, the pressure in the chamber 6 is a gas pressure P3 higher than the atmospheric pressure, that is, under pressurization, and a flash is irradiated onto the surface of the semiconductor wafer W to perform a post-film formation heat treatment of the high dielectric constant film 103. Under pressurization, the partial pressure of ammonia gas also becomes higher, and the nitriding treatment can be promoted even at a temperature lower than the treatment temperature T2 of the first embodiment. That is, the treatment temperature during the flash irradiation can be lowered.

[0250] Furthermore, in the third embodiment, the exhaust flow rate and the supply flow rate are continuously changed in a stepless manner during decompression and pressure recovery in the chamber 6. This can prevent the particles from being swirled due to a sudden change in the supply and exhaust flow.

[0251] <Fourth Embodiment>

[0252] Next, the fourth embodiment of the present invention is described. The structure of the heat treatment device 1 of the fourth embodiment is exactly the same as that of the first embodiment. In addition, the processing sequence of the semiconductor wafer W in the heat treatment device 1 of the fourth embodiment is also substantially the same as that of the first embodiment. The difference between the fourth embodiment and the first embodiment is the control of the gas environment during the heat treatment of the semiconductor wafer W.

[0253] In the first embodiment, the preheating and flash heating of the semiconductor wafer W are performed together in the gas atmosphere of ammonia gas, but in the fourth embodiment, the supply of ammonia gas is stopped during the flash heating process. Specifically, as in the first embodiment, after the semiconductor wafer W formed with the high dielectric constant film 103 is accommodated in the chamber 6, once the pressure in the chamber 6 is reduced to the pressure P1, a mixed gas of ammonia gas and nitrogen gas as a diluent gas is supplied to the heat treatment space 65 in the chamber 6 to restore to the normal pressure Ps.

[0254] After the pressure in the chamber 6 is restored to the normal pressure Ps, the 40 halogen lamps HL of the halogen heating unit 4 are lit to start the preliminary heating of the semiconductor wafer W. In the preliminary heating stage, a mixed gas of ammonia and nitrogen is supplied to the chamber 6, and the chamber 6 is also exhausted to maintain the pressure in the chamber 6 at the normal pressure Ps. That is, in the preliminary heating process, a mixed gas of ammonia and nitrogen is supplied to the chamber 6 to form an ammonia gas atmosphere. By performing preliminary heating to raise the temperature of the semiconductor wafer W to the preliminary heating temperature T1 in the ammonia gas atmosphere, the high dielectric constant film 103 can be nitrided to a certain extent.

[0255] Next, in the fourth embodiment, before the flash irradiation from the flash lamp FL is performed, the supply of ammonia gas into the chamber 6 is stopped. When the supply of ammonia gas is stopped, the supply of nitrogen gas at a flow rate corresponding to the reduced ammonia gas supply flow rate may be increased, or the exhaust flow rate may be reduced. In either case, after the supply of ammonia gas is stopped, the pressure in the chamber 6 is maintained at the normal pressure Ps.

[0256] By stopping the supply of ammonia gas while continuing to exhaust gas from the chamber 6, the ammonia concentration in the chamber 6 is reduced. And, when the ammonia concentration in the chamber 6 becomes less than one tenth of the concentration before the supply of ammonia gas is stopped, the flash heating process is performed by irradiating a flash from the flash lamp FL. In addition, in order to perform this light emission control, a concentration meter for measuring the gas concentration of ammonia gas may be provided in the chamber 6, or the time until the ammonia concentration becomes less than one tenth may be obtained in advance through experiments, and the flash irradiation may be performed at the time when the time has passed after the supply of ammonia gas is stopped.

[0257] By irradiating the semiconductor wafer W with the flash light while stopping the supply of ammonia gas to the chamber 6 , nitridation of the high dielectric constant film 103 can be suppressed and hydrogen gas that reacts with the ammonia gas and enters the high dielectric constant film 103 in the preliminary heating step can be desorbed.

[0258] The sequence after the flash heat treatment is also the same as that of the first embodiment. Specifically, after the flash heat treatment is completed, the pressure in the chamber 6 is reduced to the pressure P1 again, and then nitrogen gas is supplied into the chamber 6 to return to the normal pressure Ps. In addition, the halogen lamp HL is also turned off, and the semiconductor wafer W cooled to a predetermined temperature is unloaded from the chamber 6 of the heat treatment apparatus 1.

[0259] In the fourth embodiment, ammonia gas is supplied into the chamber 6 in the preheating step and the supply of ammonia gas into the chamber 6 is stopped during the flash irradiation, so that the high dielectric constant film 103 can be nitrided to some extent and hydrogen gas entering the high dielectric constant film 103 can be released.

[0260] <Modification>

[0261] The embodiments of the present invention have been described above, but the present invention can make various changes other than the above embodiments as long as it does not deviate from its purpose. For example, in the above embodiments, the pressure reached when the pressure in the chamber 6 is reduced, that is, the air pressure P1, is set to about 100Pa, but it is not limited to this and can also be set to an appropriate value. In order to reduce the oxygen concentration reached in the chamber 6 to about one-tenth, the pressure reached when the pressure in the chamber 6 is reduced, that is, the air pressure P1, is set to about one-tenth of the atmospheric pressure (about 10000Pa). If the air pressure P1 is set to a lower low pressure (that is, if the pressure is reduced to a lower high vacuum), although the oxygen concentration remaining in the chamber 6 can be lowered after the pressure is restored, the decompression time until the air pressure P1 is reached becomes longer. Therefore, it is preferred to set the air pressure P1 according to the balance between the oxygen concentration required when performing the post-film formation heat treatment and the production capacity.

[0262] In addition, it is preferred that the pressure reached during the decompression in the chamber 6, that is, the gas pressure P1, is set to be less than 1% of the target gas pressure (normal pressure Ps in the first embodiment, gas pressure P2 in the second embodiment, and gas pressure P3 in the third embodiment) during the heat treatment of the semiconductor wafer W. In this way, the influence of residual air on the gas environment of ammonia gas during the heat treatment of the semiconductor wafer W can be reduced.

[0263] In addition, in each of the above-mentioned embodiments, the exhaust flow rate from the chamber 6 is controlled by providing three bypass paths 197, 198, 199, but the number of bypass paths may be two or more. In addition, the exhaust flow rate from the chamber 6 may be controlled by providing a throttle valve or a gas ballast instead of providing a plurality of bypass paths 197, 198, 199. In addition, a mass flow controller may be used instead of the flow regulating valves 90, 196.

[0264] In the first and second embodiments, the exhaust flow rate from the chamber 6 is switched to two levels during decompression, and in the third embodiment, the exhaust flow rate is continuously increased in a stepless manner, but the present invention is not limited thereto, and for example, the exhaust flow rate may be switched to a plurality of levels. That is, the exhaust flow rate during decompression in the chamber 6 may be increased over time.

[0265] Similarly, regarding the air flow rate supplied to the chamber 6 when the pressure is restored, in the third embodiment, the air flow rate is continuously increased in a stepless manner, but it can also be switched to two or more levels to increase the air flow rate. That is, the air flow rate when the pressure in the chamber 6 is restored can be increased as time goes by.

[0266] In addition, when depressurizing and restoring the pressure in the chamber 6, the control unit 3 may control various valves and the like based on the elapsed time from the start of depressurization (time t1), or may perform feedback control on various valves and the like based on the measurement result of the pressure of the heat treatment space 65 measured by the pressure gauge 180. When the control is performed based on the elapsed time, the relationship between the elapsed time and the pressure in the chamber 6 may be obtained by experiment or simulation.

[0267] In addition, in each of the above-mentioned embodiments, a mixed gas of ammonia and nitrogen is supplied into the chamber 6, but the present invention is not limited thereto, and as a diluent gas mixed with ammonia, hydrogen (H2), argon (Ar), helium (He), xenon (Xe), etc. can be used. A mixed gas of any of the above-mentioned gases and ammonia can be supplied to the heat treatment space 65 to form an ammonia gas atmosphere in the chamber 6. In particular, helium is a gas used as a cooling gas because of its high heat absorption capacity, and if a mixed gas of ammonia and helium is used, the cooling rate of the semiconductor wafer W after the flash heat treatment can be increased.

[0268] In addition, as the processing gas, nitrogen oxides, oxygen, ozone and other oxygen-based reactive gases can be used. For example, there is a case where a trace amount of ozone is introduced to perform heat treatment of a high dielectric constant film. In such a case, if the residual oxygen concentration in the chamber 6 that serves as the background is sufficiently reduced, the controllability of the concentration of oxygen-based gases such as ozone is reduced. Similar to the above-mentioned embodiment, by reducing the oxygen concentration in the heat treatment space 65 in the chamber 6, the controllability of the concentration of the oxygen-based gas can be improved, and the technology of the present invention is meaningful even when using oxygen-based reactive gases.

[0269] In the fourth embodiment, the supply of ammonia gas may be stopped and the pressure in the chamber 6 may be reduced. In this case, the semiconductor wafer W is preheated in a gas atmosphere of ammonia gas at normal pressure and flash heating is performed while the pressure is reduced.

[0270] In the above-mentioned embodiments, the semiconductor wafer W ( Fig. 9 ), but the semiconductor wafer W in a state where a metal gate is deposited on the high dielectric constant film 103 can also be subjected to heat treatment. As a blank of the metal gate, for example, titanium nitride (TiN), titanium aluminum (TiAl), tungsten (W), etc. can be used. The semiconductor wafer W with a metal gate formed on the high dielectric constant film 103 is subjected to preliminary heating and flash heating treatment in the same order as the above-mentioned embodiments. Thus, a post-film formation heat treatment can be performed to eliminate multiple defects existing in the high dielectric constant film 103 after film formation.

[0271] When the semiconductor wafer W in the state where the metal gate is formed is subjected to heat treatment, the metal gate itself may be oxidized. In addition, oxygen may diffuse through the metal gate and the high dielectric constant film 103, and the film thickness of the silicon dioxide film 102 may increase. As shown in the above-mentioned embodiments, if the pressure in the chamber 6 is once reduced to the air pressure P1 and then restored to an extremely low oxygen concentration in the chamber 6 to perform preliminary heating and flash heating treatment on the semiconductor wafer W, the film thickness of the silicon dioxide film 102 can be suppressed from increasing, and oxidation of the metal gate itself can also be prevented.

[0272] In addition, the material of the substrate 101 is not limited to silicon, and may be germanium (Ge) or silicon germanium. When the material of the substrate 101 is a material other than silicon, the interface layer film formed on the base layer of the high dielectric constant film 103 may be made of a material other than silicon dioxide.

Claims

1. A heat treatment method, characterized in that: A method for heat treatment is performed by irradiating a flash of light onto a substrate having a high dielectric constant film formed thereon to heat the substrate, the method comprising: In the loading step, the substrate with the high dielectric constant film is loaded into the chamber. a decompression step of reducing the pressure in the chamber to a first pressure lower than atmospheric pressure, a pressure recovery step of supplying an oxygen-based reactive gas into the chamber to recover the pressure in the chamber from a first pressure to a second pressure higher than the first pressure, and making the oxygen concentration in the chamber less than 200 ppb, an irradiation step of irradiating a flash of light from a flash lamp onto the surface of the substrate while maintaining the pressure in the chamber at a second pressure; The second pressure is higher than the first pressure and lower than atmospheric pressure, After the irradiation step, the reactive gas is exhausted from the chamber, and the pressure in the chamber is reduced again to a pressure lower than the second pressure.

2. The heat treatment method according to claim 1, characterized in that The oxygen-based reactive gas is ozone.

3. The heat treatment method according to claim 1, characterized in that The irradiation time of the flash light is 0.1 millisecond or longer and 100 milliseconds or shorter.

4. A heat treatment method, characterized in that: A method for heat treatment is performed by irradiating a flash of light onto a substrate having a high dielectric constant film formed thereon to heat the substrate, the method comprising: In the loading step, the substrate with the high dielectric constant film is loaded into the chamber. a decompression step of reducing the pressure in the chamber to a first pressure lower than atmospheric pressure, a pressure recovery step of recovering the pressure in the chamber from a first pressure to a second pressure higher than the first pressure so that the oxygen concentration in the chamber is less than 200 ppb, an irradiation step of irradiating a surface of the substrate with a flash lamp while maintaining the pressure in the chamber at a second pressure and the oxygen concentration at 200 ppb or less, The second pressure is higher than the first pressure and lower than atmospheric pressure, After the irradiation step, the pressure in the chamber is reduced again to a pressure lower than the second pressure.

5. The heat treatment method according to claim 4, characterized in that In the pressure restoring step, a reactive gas including ammonia gas is introduced into the chamber.

6. The heat treatment method according to claim 4, characterized in that The irradiation time of the flash light is 0.1 millisecond or longer and 100 milliseconds or shorter.

7. A heat treatment method, characterized in that: A method for heat treatment is performed by irradiating a flash of light onto a substrate having a high dielectric constant film formed thereon to heat the substrate, the method comprising: The step of carrying in is to carry the substrate into the chamber, wherein the substrate has a high dielectric constant film formed on the base material via an interface layer film, and a metal gate is also formed on the high dielectric constant film. a decompression step of reducing the pressure in the chamber to a first pressure lower than atmospheric pressure, a pressure recovery step of recovering the pressure in the chamber from a first pressure to a second pressure higher than the first pressure, and making the oxygen concentration in the chamber below 200 ppb; an irradiation step of irradiating a flash of light from a flash lamp onto the surface of the substrate while maintaining the pressure in the chamber at a second pressure; The second pressure is higher than the first pressure and lower than atmospheric pressure, After the irradiation step, the pressure in the chamber is reduced again to a pressure lower than the second pressure.

8. The heat treatment method according to claim 7, characterized in that The interface layer film is a silicon oxide film.

9. The heat treatment method according to claim 7, characterized in that: The metal gate is formed of titanium nitride, titanium aluminum or tungsten.

10. The heat treatment method according to claim 7, characterized in that: In the pressure restoring step, a reactive gas including ammonia gas is introduced into the chamber.

11. The heat treatment method according to claim 7, characterized in that: The irradiation time of the flash light is 0.1 millisecond or longer and 100 milliseconds or shorter.

Images