JP7128944B2 - Heat treatment method and heat treatment apparatus - Google Patents

Description

The present invention relates to a heat treatment method and a heat treatment apparatus for forming contacts by irradiating a silicon or silicon germanium thin precision electronic substrate (hereinafter simply referred to as "substrate") such as a semiconductor wafer with flash light.

Flash lamp annealing (FLA), which heats a semiconductor wafer in an extremely short time, has attracted attention in the manufacturing process of semiconductor devices. Flash lamp annealing uses a xenon flash lamp (hereinafter simply referred to as a "flash lamp" to mean a xenon flash lamp) to irradiate the surface of the semiconductor wafer with flash light, so that only the surface of the semiconductor wafer is extremely annealed. It is a heat treatment technology that raises the temperature in a short time (several milliseconds or less).

The radiation spectral distribution of the xenon flash lamp is from the ultraviolet region to the near-infrared region, the wavelength is shorter than that of the conventional halogen lamp, and it almost matches the fundamental absorption band of the silicon semiconductor wafer. Therefore, when the semiconductor wafer is irradiated with flash light from the xenon flash lamp, it is possible to rapidly raise the temperature of the semiconductor wafer with little transmitted light. In addition, it has been found that only the vicinity of the surface of the semiconductor wafer can be selectively heated by flash light irradiation for a very short period of several milliseconds or less.

Such flash lamp annealing is used in processes that require very short heating times, such as activation of impurities typically implanted in semiconductor wafers. By irradiating the surface of a semiconductor wafer into which impurities have been implanted by ion implantation with flash light from a flash lamp, the surface of the semiconductor wafer can be heated to the activation temperature for a very short period of time, and the impurities can be deeply diffused. Therefore, only impurity activation can be performed without causing the activation of the impurities.

Application of flash lamp annealing to silicide formation of field effect transistors (FETs) is also under consideration. Silicide formation is a technique for forming a compound (silicide) of metal and silicon in order to improve the performance of field effect transistors. By forming silicide, the resistance of the gate and source/drain regions is reduced to realize high-speed operation of the field effect transistor. As metals for forming silicide, nickel (Ni), cobalt (Co), titanium (Ti), etc. are being studied, but nickel is most promising as a material most suitable for miniaturization.

Silicide formation is achieved by depositing a metal film such as nickel on the source/drain regions of a semiconductor wafer and subjecting the semiconductor wafer to heat treatment. At this time, if the heat treatment is performed for a long time, the silicide grows abnormally in the lateral direction (direction from the source/drain region to the gate) and breaks through the junction of the source/drain, resulting in a rapid increase in leakage current. occurs. For this reason, Japanese Unexamined Patent Application Publication No. 2002-100000 proposes, for example, to irradiate the surface of a semiconductor wafer on which a metal film is formed with flash light to perform heat treatment for a short period of time.

Japanese Unexamined Patent Application Publication No. 2013-84901

However, as disclosed in Patent Document 1, if a semiconductor wafer on which a metal film is formed is simply irradiated with flash light and subjected to a flash heat treatment for an extremely short time, the interface between the silicide and the silicon base layer cannot be formed. It was found that the characteristics deteriorated and became the cause of high resistance. In future devices with further miniaturization, the film thickness of silicide will be thinner and more susceptible to oxygen. In addition, since silicide itself is easily oxidized, it is also necessary to suppress oxidation of silicide after silicide is formed.

Degradation of interface characteristics of silicide and oxidation of silicide itself are caused by heat treatment in the presence of oxygen. Oxygen that causes these problems mainly includes residual oxygen in the chamber and oxygen adsorbed on the surface of the semiconductor wafer (typically adsorbed as moisture). In particular, oxygen remaining in the chamber during the flash heat treatment is a major factor in increasing the thickness of the silicon oxide film. Generally, in a flash lamp annealing apparatus, semiconductor wafers are carried in and out of a chamber under normal pressure, so oxygen in the air that flows into the chamber at this time remains in the chamber, increasing the oxygen concentration.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat treatment method and a heat treatment apparatus capable of suppressing an increase in the resistance of silicide or the like.

In order to solve the above-mentioned problems, the invention of claim 1 provides a heat treatment method for forming a contact by irradiating a substrate with flash light, wherein a loading step of loading a substrate having a metal film formed thereon into a chamber; to a first pressure lower than the atmospheric pressure; a depressurization step of depressurizing the chamber from the first pressure to a second pressure higher than the first pressure; and an irradiation step of irradiating the surface of the substrate with flash light from a flash lamp while maintaining the pressure of 2, wherein the second pressure is higher than the first pressure and lower than the atmospheric pressure, and the pressure is restored. In the step, the oxygen concentration in the chamber after pressure recovery is set to 200 ppb or less, and after the irradiation step, an inert gas is supplied into the chamber to restore the pressure in the chamber to atmospheric pressure. The valve for supplying air is also opened while the valve for supplying air is kept open.

According to a second aspect of the invention, in the heat treatment method according to the first aspect of the invention, in the depressurization step, the exhaust flow rate from the chamber is increased with time.

According to a third aspect of the invention, in the heat treatment method according to the first or second aspect of the invention, in the pressure recovery step, the flow rate of air supplied to the chamber is increased with time.

In addition, the invention of claim 4 is the heat treatment method according to any one of claims 1 to 3, wherein after the irradiation step, the pressure inside the chamber is set to atmospheric pressure of 50 liters/minute or more and 100 liters/minute or less. is characterized by flowing an inert gas into the chamber at a flow rate of

Further, according to the invention of claim 5, in the heat treatment method according to any one of claims 1 to 4, in the carrying-in step, an inert gas is introduced into the chamber while opening the carrying opening of the chamber. is characterized by supplying

According to a sixth aspect of the present invention, there is provided a heat treatment method for forming a contact by irradiating a substrate with flash light, wherein the step of loading the substrate on which a metal film is formed into a chamber; a decompression step of decompressing to a low first pressure; and an irradiation step of irradiating the surface of the substrate with flash light from a flash lamp while maintaining the inside of the chamber at the first pressure. When the oxygen concentration in the chamber is set to 200 ppb or less, and after the irradiation step, an inert gas is supplied into the chamber to restore the pressure in the chamber to atmospheric pressure, the exhaust valve is left open. A valve for supplying air is also opened.

According to a seventh aspect of the present invention, there is provided a heat treatment apparatus for forming a contact by irradiating a substrate with flash light, wherein a chamber containing a substrate on which a metal film is formed and a flash light are applied to the substrate contained in the chamber. a flash lamp for irradiation, an exhaust unit for exhausting the atmosphere in the chamber, a gas supply unit for supplying a predetermined processing gas to the chamber, and after reducing the pressure in the chamber to a first pressure lower than atmospheric pressure. a control unit for controlling the exhaust unit and the gas supply unit so that the surface of the substrate is irradiated with flash light from the flash lamp while the pressure is restored to a second pressure higher than the first pressure; wherein the second pressure is higher than the first pressure and lower than atmospheric pressure, and the oxygen concentration in the chamber after restoring the pressure in the chamber to the second pressure is 200 ppb or less, and the control unit After irradiation with the flash light, when the inert gas is supplied into the chamber to restore the pressure in the chamber to atmospheric pressure, the valve of the gas supply unit is opened while the valve of the exhaust unit is open. characterized by

Further, according to the eighth aspect of the invention, there is provided the heat treatment apparatus according to the seventh aspect of the invention, wherein when the control unit reduces the pressure in the chamber to the first pressure, the exhaust flow rate from the chamber increases with time. It is characterized in that the exhaust part is controlled as follows.

According to a ninth aspect of the invention, in the heat treatment apparatus according to the seventh or eighth aspect of the invention, when the pressure inside the chamber is restored from the first pressure to the second pressure, the chamber The gas supply unit is controlled so that the flow rate of air supplied to the is increased with time.

Further, the invention of claim 10 is the heat treatment apparatus according to any one of claims 7 to 9, wherein after the irradiation with the flash light, the control unit controls the inside of the chamber to have an atmospheric pressure of 50 liters/minute. The exhaust part and the gas supply part are controlled so that the inert gas flows into the chamber at a flow rate of 100 liters/minute or less.

According to an eleventh aspect of the invention, there is provided a heat treatment apparatus for forming a contact by irradiating a substrate with flash light, wherein a chamber containing a substrate on which a metal film is formed and a flash light being applied to the substrate contained in the chamber. a flash lamp for irradiation, an exhaust unit for exhausting the atmosphere in the chamber, a gas supply unit for supplying a predetermined processing gas to the chamber, and after reducing the pressure in the chamber to a first pressure lower than atmospheric pressure. and a control unit for controlling the exhaust unit and the gas supply unit so that the surface of the substrate is irradiated with flash light from the flash lamp while the pressure is maintained at a first pressure; The oxygen concentration in the chamber after the pressure is reduced to 200 ppb or less, and after the irradiation with the flash light, the control unit supplies an inert gas into the chamber to restore the pressure in the chamber to atmospheric pressure. When pressurizing, the valve of the gas supply section is also opened while the valve of the exhaust section is kept open.

According to the inventions of claims 1 to 5, since the pressure inside the chamber is reduced to the first pressure lower than the atmospheric pressure and then restored to the second pressure higher than that, the flash light is emitted. It is possible to reduce the oxygen concentration in the chamber when the contact resistance is reduced. Moreover, since the second pressure is higher than the first pressure and lower than the atmospheric pressure, the time required for pressure recovery is shortened, and the throughput can be improved.

In particular, according to the second aspect of the invention, since the exhaust flow rate from the chamber is increased with time, it is possible to prevent the particles from being stirred up due to the exhaust from the chamber.

In particular, according to the third aspect of the invention, since the flow rate of air supplied to the chamber is increased with time, it is possible to prevent particles from being stirred up due to the supply of air to the chamber.

In particular, according to the fourth aspect of the invention, since the inert gas is flowed into the chamber at a flow rate of 50 liters/minute or more and 100 liters/minute or less with the inside of the chamber being atmospheric pressure, particles generated during flash light irradiation are removed from the chamber. It can be pushed outside.

In particular, according to the fifth aspect of the present invention, in the loading step, the inert gas is supplied into the chamber while opening the transfer opening of the chamber, so that air can be prevented from flowing into the chamber when the substrate is loaded. .

According to the sixth aspect of the invention, the pressure in the chamber is reduced to a first pressure lower than the atmospheric pressure, and the flash light is emitted to irradiate the surface of the substrate with the flash light while maintaining the first pressure. At this time, the oxygen concentration in the chamber can be reduced, and the contact resistance can be reduced.

According to the seventh to tenth aspects of the invention, after reducing the pressure in the chamber to the first pressure lower than the atmospheric pressure, the pressure is restored to the second pressure higher than the first pressure. can reduce the oxygen concentration in the chamber when irradiating , and can reduce the contact resistance. Moreover, since the second pressure is higher than the first pressure and lower than the atmospheric pressure, the time required for pressure recovery is shortened, and the throughput can be improved.

In particular, according to the eighth aspect of the invention, since the exhaust section is controlled so that the flow rate of exhaust gas from the chamber increases with time, it is possible to prevent particles from being stirred up due to the exhaust gas from the chamber.

In particular, according to the ninth aspect of the invention, since the gas supply section is controlled so that the flow rate of air supplied to the chamber increases with time, it is possible to prevent particles from being stirred up when air is supplied to the chamber.

In particular, according to the invention of claim 10, since the inert gas is flowed into the chamber at a flow rate of 50 liters/minute or more and 100 liters/minute or less with the inside of the chamber being atmospheric pressure, particles generated during flash light irradiation are removed from the chamber. It can be pushed outside.

According to the eleventh aspect of the invention, the pressure in the chamber is reduced to the first pressure lower than the atmospheric pressure, and the flash light is emitted to irradiate the surface of the substrate with the flash light while maintaining the first pressure. At this time, the oxygen concentration in the chamber can be reduced, and the contact resistance can be reduced.

1 is a vertical cross-sectional view showing the configuration of a heat treatment apparatus according to the present invention; FIG. It is a perspective view which shows the whole external appearance of a holding|maintenance part. It is the top view which looked at the holding|maintenance part from the upper surface. It is the side view which looked at the holding|maintenance part from the side. It is a top view of a transfer mechanism. It is a side view of a transfer mechanism. FIG. 4 is a plan view showing the arrangement of a plurality of halogen lamps; It is a figure which shows the structure of an exhaust part. It is a figure which shows the structure by which the metal film was formed into a film on the semiconductor wafer. It is a figure which shows the pressure change in the chamber in 1st Embodiment. It is a figure which shows the pressure change in the chamber in 2nd Embodiment. It is a figure which shows the pressure change in the chamber in 3rd Embodiment. It is a figure which shows the pressure change in the chamber in 4th Embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<First embodiment>
FIG. 1 is a vertical cross-sectional view showing the configuration of a heat treatment apparatus 1 according to the present invention. The heat treatment apparatus 1 of this embodiment is a flash lamp annealing apparatus that heats a disk-shaped semiconductor wafer W as a substrate by irradiating the semiconductor wafer W with flash light. Although the size of the semiconductor wafer W to be processed is not particularly limited, it is, for example, φ300 mm or φ450 mm. A metal film such as nickel is formed on the semiconductor wafer W before being carried into the heat treatment apparatus 1, and silicide, which is a compound of the metal and silicon, is formed and grown by the heat treatment by the heat treatment apparatus 1. In addition, in FIG. 1 and subsequent figures, the dimensions and numbers of each part are exaggerated or simplified as necessary for easy understanding.

The heat treatment apparatus 1 includes a chamber 6 containing a semiconductor wafer W, a flash heating section 5 containing a plurality of flash lamps FL, and a halogen heating section 4 containing a plurality of halogen lamps HL. A flash heating section 5 is provided on the upper side of the chamber 6, and a halogen heating section 4 is provided on the lower side. The heat treatment apparatus 1 also includes a holding unit 7 that holds the semiconductor wafer W in a horizontal posture inside the chamber 6, a transfer mechanism 10 that transfers the semiconductor wafer W between the holding unit 7 and the outside of the apparatus, Prepare. Further, the heat treatment apparatus 1 includes a control section 3 that controls each operation mechanism provided in the halogen heating section 4, the flash heating section 5, and the chamber 6 to perform the heat treatment of the semiconductor wafer W. As shown in FIG.

The chamber 6 is configured by mounting chamber windows made of quartz on the upper and lower sides of a cylindrical chamber side portion 61 . The chamber side part 61 has a substantially cylindrical shape with upper and lower openings, the upper opening being closed by an upper chamber window 63, and the lower opening being closed by a lower chamber window 64. ing. The upper chamber window 63 forming the ceiling of the chamber 6 is a disc-shaped member made of quartz and functions as a quartz window through which the flash light emitted from the flash heating unit 5 is transmitted into the chamber 6 . A lower chamber window 64 forming the floor of the chamber 6 is also a disk-shaped member made of quartz and functions as a quartz window through which the light from the halogen heating unit 4 is transmitted into the chamber 6 . The thickness of upper chamber window 63 and lower chamber window 64 is, for example, about 28 mm.

A reflecting ring 68 is attached to the upper portion of the inner wall surface of the chamber side portion 61, and a reflecting ring 69 is attached to the lower portion thereof. Both the reflecting rings 68 and 69 are formed in an annular shape. The upper reflector ring 68 is attached by fitting from the upper side of the chamber side 61 . On the other hand, the lower reflecting ring 69 is attached by fitting from the lower side of the chamber side portion 61 and fastening with screws (not shown). That is, both the reflecting rings 68 and 69 are detachably attached to the chamber side portion 61 . A space inside the chamber 6 , that is, a space surrounded by the upper chamber window 63 , the lower chamber window 64 , the chamber side portion 61 and the reflective rings 68 and 69 is defined as a thermal processing space 65 .

A concave portion 62 is formed in the inner wall surface of the chamber 6 by attaching the reflecting rings 68 and 69 to the chamber side portion 61 . That is, the recess 62 is formed by the central portion of the inner wall surface of the chamber side portion 61 where the reflecting rings 68 and 69 are not attached, the lower end surface of the reflecting ring 68, and the upper end surface of the reflecting ring 69. . The concave portion 62 is formed in an annular 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. As shown in FIG.

The chamber side portion 61 and the reflecting rings 68, 69 are made of a metallic material (for example, stainless steel) having excellent strength and heat resistance. The inner peripheral surfaces of the reflecting rings 68 and 69 are mirror-finished by electrolytic nickel plating.

A transfer opening (furnace port) 66 for transferring the semiconductor wafer W into and out of the chamber 6 is formed in the chamber side portion 61 . The transport opening 66 can be opened and closed by a gate valve 185 . The conveying opening 66 is communicated with the outer peripheral surface of the recess 62 . Therefore, when the gate valve 185 opens the transfer opening 66 , the semiconductor wafer W can be transferred from the transfer opening 66 to the heat treatment space 65 through the recess 62 and transferred from the heat treatment space 65 . It can be performed. Further, when the gate valve 185 closes the transfer opening 66, the heat treatment space 65 in the chamber 6 becomes a sealed space.

A gas supply hole 81 for supplying a processing gas (nitrogen gas (N ₂ ) in this embodiment) to the heat treatment space 65 is formed in the upper portion of the inner wall of the chamber 6 . The gas supply hole 81 is formed above the recess 62 and may be provided in the reflection ring 68 . The gas supply hole 81 is communicated with a gas supply pipe 83 through an annular buffer space 82 formed inside the side wall of the chamber 6 . The gas supply pipe 83 is connected to a gas supply source 85 . The gas supply source 85 supplies nitrogen gas as a processing gas to the gas supply pipe 83 under the control of the controller 3 . A valve 84 and a flow control valve 90 are interposed in the middle of the path of the gas supply pipe 83 . When valve 84 is opened, process gas is delivered from gas supply 85 to buffer space 82 . The flow rate of the processing gas supplied to the buffer space 82 through the gas supply pipe 83 is adjusted by a flow rate control valve 90 . The flow rate of the processing gas defined by the flow rate control valve 90 is made variable by the control of the controller 3 . The processing gas that has flowed into the buffer space 82 flows so as to expand in the buffer space 82 , which has a smaller fluid resistance than the gas supply hole 81 , and is supplied from the gas supply hole 81 into the heat treatment space 65 . The processing gas is not limited to nitrogen gas, and inert gas such as argon (Ar) and helium (He), hydrogen (H ₂ ), ammonia (NH ₃ ), chlorine (Cl ₂ ), It may be a reactive gas such as hydrogen chloride (HCl).

On the other hand, a gas exhaust hole 86 for exhausting the gas in the heat treatment space 65 is formed in the lower part of the inner wall of the chamber 6 . The gas exhaust hole 86 is formed below the recess 62 and may be provided in the reflecting ring 69 . The gas exhaust hole 86 is communicated with a gas exhaust pipe 88 through an annular buffer space 87 formed inside the side wall of the chamber 6 . The gas exhaust pipe 88 is connected to the exhaust section 190 . A valve 89 is inserted in the middle of the path of the gas exhaust pipe 88 . When the valve 89 is opened, the gas in the heat treatment space 65 is discharged from the gas exhaust hole 86 to the gas exhaust pipe 88 through the buffer space 87 . A plurality of gas supply holes 81 and gas exhaust holes 86 may be provided along the circumferential direction of the chamber 6, or may be slit-shaped.

FIG. 8 is a diagram showing the configuration of the exhaust section 190. As shown in FIG. The exhaust section 190 includes an exhaust pump 191 , a flow control valve 196 , three bypass lines 197 , 198 and 199 and three exhaust valves 192 , 193 and 194 . A gas exhaust pipe 88 that guides exhaust from the chamber 6 and an exhaust pump 191 are connected by three bypass lines 197 , 198 and 199 . Three bypass lines 197, 198, 199 are provided in parallel. The three bypass lines 197, 198, 199 have different pipe diameters. Bypass line 197 has the smallest diameter, bypass line 199 has the largest diameter, and bypass line 198 has a diameter in between. Therefore, the flow rate of gas that can pass through bypass lines 197 , 198 , 199 increases in this order.

Three exhaust valves 192, 193, 194 are provided on three bypass lines 197, 198, 199, respectively. That is, an exhaust valve 192 is interposed in the bypass line 197 , an exhaust valve 193 is interposed in the bypass line 198 , and an exhaust valve 194 is interposed in the bypass line 199 . When the three exhaust valves 192, 193, 194 are opened while operating the exhaust pump 191, the exhaust from the chamber 6 guided by the gas exhaust pipe 88 passes through the corresponding bypass lines 197, 198, 199 to the exhaust pump. Attracted to 191.

Since the three bypass lines 197, 198, 199 have different pipe diameters, they have different exhaust capacities. The larger the pipe diameter, the greater the exhaust capacity. Therefore, the exhaust flow rate from the chamber 6 can be controlled by which of the three exhaust valves 192, 193, 194 is opened or closed. Only one of the three exhaust valves 192, 193, 194 may be opened, or two or three may be opened. For example, when the exhaust valves 193 and 194 are closed and only the exhaust valve 192 is opened, exhaust is performed with the smallest exhaust flow rate. Further, when all the three exhaust valves 192, 193, 194 are opened, exhaust is performed with the largest exhaust flow rate.

A flow control valve 196 is interposed between the junction of the three bypass lines 197 , 198 , 199 and the exhaust pump 191 . The exhaust flow rate of the gas exhaust pipe 88 can also be adjusted by the flow rate control valve 196 . The exhaust flow rate defined by the flow control valve 196 is made variable by the control of the controller 3 . While the three bypass lines 197, 198, 199 are a mechanism for discontinuously and multistagely adjusting the exhaust flow rate, the flow control valve 196 is a mechanism for continuously and steplessly adjusting the exhaust flow rate.

The gas supply pipe 83, the gas exhaust pipe 88, and the three bypass lines 197, 198, 199 are made of stainless steel with excellent strength and corrosion resistance. A pressure gauge 180 for measuring the pressure in the heat treatment space 65 is provided inside the chamber 6 . The pressure gauge 180 preferably has a measurement range of about 5 Pa to 0.2 MPa.

FIG. 2 is a perspective view showing the overall appearance of the holding portion 7. As shown in FIG. 3 is a plan view of the holding portion 7 viewed from above, and FIG. 4 is a side view of the holding portion 7 viewed from the side. The holding portion 7 includes a base ring 71 , a connecting portion 72 and a susceptor 74 . The base ring 71, the connecting portion 72 and the susceptor 74 are all made of quartz. That is, the entire holding portion 7 is made of quartz.

The base ring 71 is an annular 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 FIG. 1). A plurality of connecting portions 72 (four in this embodiment) are erected along the circumferential direction on the upper surface of the base ring 71 having an annular shape. The connecting portion 72 is also a quartz member and is fixed to the base ring 71 by welding. In addition, the shape of the base ring 71 may be an arc shape that is partially missing from an annular shape.

A flat susceptor 74 is supported by four connecting portions 72 provided on the base ring 71 . The susceptor 74 is a substantially circular flat member made of quartz. The diameter of the susceptor 74 is larger than the diameter of the semiconductor wafer W. That is, the susceptor 74 has a planar size larger than the semiconductor wafer W. As shown in FIG. A plurality of (five in this embodiment) guide pins 76 are erected on the upper surface of the susceptor 74 . Five guide pins 76 are provided along a circle concentric with the outer circumference of the susceptor 74 . The diameter of the circle in 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 made of quartz. The guide pin 76 may be machined from a quartz ingot integrally with the susceptor 74, or may be separately machined and attached to the susceptor 74 by welding or the like.

The four connecting portions 72 erected on the base ring 71 and the lower surface of the peripheral portion of the susceptor 74 are fixed by welding. That is, the susceptor 74 and the base ring 71 are fixedly connected by the connecting portion 72, and the holding portion 7 is an integrally molded member of quartz. The holder 7 is attached to the chamber 6 by supporting the base ring 71 of the holder 7 on the wall surface of the chamber 6 . When the holding part 7 is attached to the chamber 6, the substantially disc-shaped susceptor 74 is in a horizontal posture (a posture in which the normal line is aligned with the vertical direction). The semiconductor wafer W carried into the chamber 6 is placed and held in a horizontal posture on the susceptor 74 of the holding section 7 mounted in the chamber 6 . By placing the semiconductor wafer W inside the circle formed by the five guide pins 76, it is prevented from being displaced in the horizontal direction. The number of guide pins 76 is not limited to five, and may be any number that can prevent the semiconductor wafer W from being displaced.

Further, as shown in FIGS. 2 and 3, the susceptor 74 is formed with an opening 78 and a notch 77 penetrating vertically. The notch 77 is provided for passing the probe tip of a contact thermometer 130 using a thermocouple. On the other hand, the opening 78 is provided so that the radiation thermometer 120 receives radiation light (infrared light) emitted from the lower surface of the semiconductor wafer W held by the susceptor 74 . Further, the susceptor 74 is formed with four through holes 79 through which lift pins 12 of the transfer mechanism 10, which will be described later, penetrate to transfer the semiconductor wafer W. As shown in FIG.

FIG. 5 is a plan view of the transfer mechanism 10. FIG. 6 is a side view of the transfer mechanism 10. FIG. The transfer mechanism 10 includes two transfer arms 11 . The transfer arm 11 has an arc shape along the generally annular concave portion 62 . Two lift pins 12 are erected on each transfer arm 11 . Each transfer arm 11 is rotatable by a horizontal movement mechanism 13 . The horizontal movement mechanism 13 moves the pair of transfer arms 11 to the transfer operation position (solid line position in FIG. It is horizontally moved to and from the retracted position (the two-dot chain line position in FIG. 5) that does not overlap in plan view. As the horizontal movement mechanism 13, each transfer arm 11 may be rotated by an individual motor. It may be something that moves.

Also, the pair of transfer arms 11 is vertically moved together with the horizontal movement mechanism 13 by the lifting mechanism 14 . When the lifting mechanism 14 lifts the pair of transfer arms 11 to the transfer operation position, a total of four lift pins 12 pass through the through holes 79 (see FIGS. 2 and 3) drilled in the susceptor 74, and the lift pins 12 protrudes from the upper surface of the susceptor 74 . On the other hand, when the lifting mechanism 14 lowers the pair of transfer arms 11 to the transfer operation position and removes the lift pins 12 from the through-holes 79, the horizontal movement mechanism 13 moves the pair of transfer arms 11 so as to open them. The 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 section 7 . Since the base ring 71 is placed on the bottom surface of the recess 62 , the retracted position of the transfer arm 11 is inside the recess 62 .

Returning to FIG. 1, the flash heating unit 5 provided above the chamber 6 includes a light source composed of a plurality of (30 in this embodiment) xenon flash lamps FL inside a housing 51, and a lamp above the light source. and a reflector 52 provided to cover the . A lamp light emission window 53 is attached to the bottom of the housing 51 of the flash heating unit 5 . The lamp light emission window 53 forming the floor of the flash heating unit 5 is a plate-shaped quartz window made of quartz. By installing the flash heating unit 5 above the chamber 6 , the lamp light emission window 53 faces the upper chamber window 63 . The flash lamp FL irradiates the heat treatment space 65 with flash light from above the chamber 6 through the lamp light emission window 53 and the upper chamber window 63 .

Each of the plurality of flash lamps FL is a rod-shaped lamp having an elongated cylindrical shape, and the longitudinal direction of each flash lamp FL is along the main surface of the semiconductor wafer W held by the holding portion 7 (that is, along the horizontal direction). They are arranged in a plane so as to be parallel to each other. Therefore, the plane formed by the arrangement of the flash lamps FL is also a horizontal plane.

The xenon flash lamp FL is composed of a rod-shaped glass tube (discharge tube) in which xenon gas is filled and an anode and a cathode connected to a condenser are arranged at both ends of the tube (discharge tube), and an outer peripheral surface of the glass tube is provided. and a trigger electrode. Since xenon gas is an electrical insulator, electricity does not flow in the glass tube under normal conditions even if electric charges are accumulated in the capacitor. However, when a high voltage is applied to the trigger electrode to break down the insulation, the electricity stored in the capacitor instantly flows into the glass tube, and the xenon atoms or molecules are excited at that time to emit light. 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 millisecond to 100 milliseconds. It has the characteristic of being able to irradiate extremely strong light compared to the light source. That is, the flash lamp FL is a pulsed light emitting lamp that instantaneously emits light in an extremely short time of less than 1 second. The light emission time of the flash lamp FL can be adjusted by the coil constant of the lamp power source that supplies power to the flash lamp FL.

Moreover, the reflector 52 is provided above the plurality of flash lamps FL so as to cover them as a whole. The basic function of the reflector 52 is to reflect the flash light emitted from the plurality of flash lamps FL to the heat treatment space 65 side. The reflector 52 is made of an aluminum alloy plate, and its surface (the surface facing the flash lamp FL) is roughened by blasting.

The halogen heating unit 4 provided below the chamber 6 incorporates a plurality of (40 in this embodiment) halogen lamps HL inside a housing 41 . The halogen heating unit 4 is a light irradiation unit that heats the semiconductor wafer W by irradiating the heat treatment space 65 with light from the lower side of the chamber 6 through the lower chamber window 64 using a plurality of halogen lamps HL.

FIG. 7 is a plan view showing the arrangement of multiple halogen lamps HL. The 40 halogen lamps HL are arranged in two upper and lower stages. Twenty halogen lamps HL are arranged in the upper stage near the holding part 7, and twenty halogen lamps HL are arranged in the lower stage farther from the holding part 7 than the upper stage. Each halogen lamp HL is a rod-shaped lamp having an elongated cylindrical shape. The 20 halogen lamps HL in both the upper stage and the lower stage are arranged so that their longitudinal directions are parallel to each other along the main surface of the semiconductor wafer W held by the holding portion 7 (that is, along the horizontal direction). there is Therefore, the plane formed by the arrangement of the halogen lamps HL in both the upper stage and the lower stage is a horizontal plane.

Further, as shown in FIG. 7, the arrangement density of the halogen lamps HL in both the upper and lower stages is higher in the region facing the peripheral portion than in the region facing the central portion of the semiconductor wafer W held by the holding portion 7. there is That is, in both the upper and lower stages, the arrangement pitch of the halogen lamps HL is shorter in the peripheral portion than in the central portion of the lamp arrangement. Therefore, it is possible to irradiate a larger amount of light to the peripheral portion of the semiconductor wafer W, which tends to cause a temperature drop during heating by light irradiation from the halogen heating unit 4 .

A group of halogen lamps HL in the upper stage and a group of halogen lamps HL in the lower stage are arranged so as to cross each other in a grid pattern. That is, a total of 40 halogen lamps HL are arranged such that the longitudinal direction of the 20 halogen lamps HL arranged in the upper stage and the longitudinal direction of the 20 halogen lamps HL arranged in the lower stage are perpendicular to each other. there is

The halogen lamp HL is a filament-type light source that emits light by turning the filament incandescent by energizing the filament arranged inside the glass tube. Inside the glass tube, a gas obtained by introducing a small amount of a halogen element (iodine, bromine, etc.) into an inert gas such as nitrogen or argon is sealed. By introducing a halogen element, it becomes possible to set the temperature of the filament to a high temperature while suppressing breakage of the filament. Therefore, the halogen lamp HL has characteristics that it has a longer life than a normal incandescent lamp and can continuously irradiate strong light. That is, the halogen lamp HL is a continuous lighting lamp that continuously emits light for at least one second. Further, since the halogen lamp HL is a rod-shaped lamp, it has a long life. By arranging the halogen lamp HL along the horizontal direction, the radiation efficiency to the semiconductor wafer W above is excellent.

In addition, a reflector 43 is provided below the two-stage halogen lamp HL in the housing 41 of the halogen heating unit 4 (FIG. 1). The reflector 43 reflects the light emitted from the plurality of halogen lamps HL to the heat treatment space 65 side.

The control unit 3 controls the various operating mechanisms provided in the heat treatment apparatus 1 . The hardware configuration of the control unit 3 is the same as that of a general computer. That is, the control unit 3 includes a CPU that is a circuit that performs various arithmetic processing, a ROM that is a read-only memory that stores basic programs, a RAM that is a readable and writable memory that stores various information, and control software and data. Equipped with a magnetic disk for storage. The processing in the heat treatment apparatus 1 proceeds as the CPU of the control unit 3 executes a predetermined processing program. In addition, the control unit 3 controls the valve 84 , the valve 89 , the flow rate adjustment valve 90 , the flow rate adjustment valve 196 , the exhaust pump 191 , and the three exhaust valves 192 , 193 , 194 to control the heat treatment space 65 in the chamber 6 . Adjust pressure, supply air flow and exhaust rate.

In addition to the above configuration, the heat treatment apparatus 1 prevents excessive temperature rise of the halogen heating section 4, the flash heating section 5, and the chamber 6 due to thermal energy generated from the halogen lamps HL and the flash lamps FL during the heat treatment of the semiconductor wafer W. Therefore, it has various cooling structures. For example, the walls of the chamber 6 are provided with water cooling pipes (not shown). The halogen heating unit 4 and the flash heating unit 5 have an air-cooling structure in which heat is exhausted by forming a gas flow inside. Air is also supplied to the gap between the upper chamber window 63 and the lamp light emission window 53 to cool the flash heating part 5 and the upper chamber window 63 .

Next, a procedure for processing the semiconductor wafer W in the heat treatment apparatus 1 will be described. The semiconductor wafer W to be processed here is a semiconductor substrate in which a metal film is formed on a base material of silicon. The heat treatment apparatus 1 irradiates the semiconductor wafer W with flash light to heat it, thereby forming a silicide.

FIG. 9 is a diagram showing a structure in which a metal film is formed on a semiconductor wafer W. As shown in FIG. A silicon oxide film (SiO ₂ ) 102 is formed on a silicon base material 101 of a semiconductor wafer W. As shown in FIG. The silicon oxide film 102 is a layer necessary as an interfacial layer film between the silicon substrate 101 and the high dielectric constant film 103 . The film thickness of the silicon oxide film 102 is extremely thin, for example, about 1 nm. As a method for forming the silicon oxide film 102, various known methods such as a thermal oxidation method can be adopted.

A high dielectric constant film 103 is formed as a gate insulating film on the silicon oxide film 102 . High dielectric constant materials such as HfO ₂ , ZrO ₂ , Al ₂ O ₃ and La ₂ O ₃ can be used as the high dielectric constant film 103 (HfO ₂ in this embodiment). The high dielectric constant film 103 is formed by depositing a high dielectric constant material on the silicon oxide film 102 by ALD (Atomic Layer Deposition), for example. Although the film thickness of the high dielectric constant film 103 deposited on the silicon oxide film 102 is several nanometers, its equivalent silicon oxide film thickness (EOT: Equivalent oxide thickness) is about 1 nm. The method of forming the high dielectric constant film 103 is not limited to ALD, and a known method such as MOCVD (Metal Organic Chemical Vapor Deposition) can be adopted.

A gate electrode 105 is formed on the high dielectric constant film 103 . The gate electrode 105 of this embodiment is a so-called metal gate electrode made of titanium (Ti) or titanium nitride (TiN). As the gate electrode 105, polysilicon may be used instead of the metal gate electrode. SiN sidewalls 104 are formed on both sides of the gate electrode 105 . The sidewall 104 is formed prior to the high dielectric constant film 103 in the gate last process.

Both sides of the gate electrode 105 on the upper surface of the silicon substrate 101 become source/drain regions (regions separated by dotted lines in FIG. 9). Ions are implanted into the source/drain regions by an ion implanter.

A metal film 108 is formed on the source/drain regions. Metal materials used in the silicide technology are, for example, nickel (Ni), cobalt (Co), titanium (Ti), tungsten (W), etc. (nickel in this embodiment). The metal film 108 can be formed by a known film forming technique such as sputtering or vacuum deposition.

A heat treatment apparatus 1 performs heat treatment on a semiconductor wafer W in which a metal film 108 is formed on the source/drain regions of a base material 101 of silicon as shown in FIG. An operation procedure in the heat treatment apparatus 1 will be described below. The operation procedure of the heat treatment apparatus 1 proceeds as the control unit 3 controls each operating mechanism of the heat treatment apparatus 1 .

First, the semiconductor wafer W with the metal film 108 formed thereon is carried into the chamber 6 of the heat treatment apparatus 1 . When the semiconductor wafer W is loaded, the gate valve 185 is opened to open the transfer opening 66 , and the semiconductor wafer W with the metal film 108 formed thereon is transferred through the transfer opening 66 into the chamber 6 by a transfer robot outside the apparatus. It is carried into the heat treatment space 65 . At this time, since the inside and outside of the chamber 6 are both at atmospheric pressure, air is caught in the heat treatment space 65 inside the chamber 6 as the semiconductor wafer W is carried. Therefore, by opening the valve 84 and continuing to supply nitrogen gas from the gas supply source 85 into the chamber 6 , the nitrogen gas flow is allowed to flow out from the opened transfer opening 66 , and the atmosphere outside the apparatus flows into the chamber 6 . may be minimized. In addition, when the gate valve 185 is opened, it is preferable to increase the supply flow rate of the nitrogen gas more than during the heat treatment of the semiconductor wafer W (for example, if the heat treatment is normally 30 liters/minute, when the gate valve 185 is opened, the flow rate is 120 liters/minute). /min). Furthermore, it is preferable to increase the supply flow rate of nitrogen gas and close the valve 89 to stop the exhaust from the chamber 6 . As a result, the nitrogen gas supplied into the chamber 6 flows out only from the transfer opening 66, so that the inflow of outside air can be more effectively prevented.

The semiconductor wafer W carried in by the transfer robot advances to a position directly above the holding part 7 and stops there. When the pair of transfer arms 11 of the transfer mechanism 10 moves horizontally from the retracted position to the transfer operation position and rises, the lift pins 12 protrude from the upper surface of the susceptor 74 through the through holes 79 and the semiconductor wafer W is moved. receive.

After the semiconductor wafer W is placed on the lift pins 12 , the transfer robot leaves the heat treatment space 65 and the transfer opening 66 is closed by the gate valve 185 . By lowering the pair of transfer arms 11, the semiconductor wafer W is transferred from the transfer mechanism 10 to the susceptor 74 of the holder 7 and held in a horizontal position. The semiconductor wafer W is held by the susceptor 74 with the surface on which the metal film 108 is formed facing up. Also, the semiconductor wafer W is held inside five guide pins 76 on the upper surface of the susceptor 74 . The pair of transfer arms 11 that have descended below the susceptor 74 are retracted by the horizontal movement mechanism 13 to the retracted position, that is, to the inside of the recess 62 .

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 inside the chamber 6 is reduced to a pressure lower than the atmospheric pressure. Specifically, the heat treatment space 65 in the chamber 6 becomes a sealed space by closing the transfer opening 66 . In this state, the valve 84 for air supply is closed while the valve 89 for exhaust is opened. Further, while operating the exhaust pump 191 , the control unit 3 opens the exhaust valve 192 provided in the bypass line 197 having the smallest pipe diameter among the three bypass lines 197 , 198 and 199 . Other exhaust valves 193, 194 are closed. As a result, the inside of the chamber 6 is exhausted without being supplied with gas, and the heat treatment space 65 inside the chamber 6 is decompressed.

FIG. 10 is a diagram showing pressure changes within the chamber 6 in the first embodiment. In the figure, the horizontal axis indicates the time, and the vertical axis indicates the pressure inside the chamber 6 . When the semiconductor wafer W is accommodated in the chamber 6 and the transfer opening 66 is closed, the pressure inside the chamber 6 is normal pressure Ps (=atmospheric pressure=approximately 101325 Pa). Then, pressure reduction in the chamber 6 is started at time t1. At the initial stage of pressure reduction, only the bypass line 197, which has the smallest pipe diameter among the three bypass lines 197, 198, and 199, is used, so the exhaust flow rate is small and the exhaust speed is relatively slow.

Next, at time t2, the controller 3 opens all three exhaust valves 192, 193, and 194. As shown in FIG. As a result, the exhaust flow rate from the chamber 6 increases, and the exhaust speed also increases. At time t3, the pressure (degree of vacuum) of the chamber 6 reaches the atmospheric pressure P1. The atmospheric pressure P1 is approximately 100 Pa, for example. That is, in the initial stage of decompression, exhaust is performed with a small exhaust flow rate, and then the exhaust flow is switched to a larger exhaust flow rate to perform exhaust. In addition, in the first embodiment, the flow rate of the flow control valve 196 is constant.

When the chamber 6 is rapidly exhausted at a large exhaust flow rate from the start of depressurization, a large change in air current occurs in the chamber 6, and particles adhering to the structure of the chamber 6 (for example, the lower chamber window 64) are blown up. There is a risk that the semiconductor wafer W will be re-adhered and contaminated. In the initial stage of depressurization, the particles in the chamber 6 can be prevented from being stirred up by gently exhausting with a small exhaust flow rate and then switching to a large exhaust flow rate.

At time t3 when the pressure in the chamber 6 reaches the atmospheric pressure P1, the valve 89 for exhaust is closed and the valve 84 for air supply is opened, and nitrogen is supplied from the gas supply source 85 to the heat treatment space 65 in the chamber 6. Supply gas. As a result, a nitrogen atmosphere is formed around the semiconductor wafer W held by the holding portion 7 in the chamber 6 . Even while the nitrogen gas is being supplied to the chamber 6, the exhaust from the chamber 6 may be performed using only the bypass line 197 having the smallest pipe diameter. In this case, of course, the supply flow rate of the processing gas is greater than the exhaust flow rate.

By supplying nitrogen gas into the chamber 6, the pressure inside the chamber 6 rises from the atmospheric pressure P1 and returns to the normal pressure Ps at time t4. In the first embodiment, the inside of the chamber 6 is once decompressed to the atmospheric pressure P1 and then restored to the normal pressure Ps. It can be 200 ppb or less.

After time t4 when the pressure in the chamber 6 returns to the normal pressure Ps, the flow rate of the nitrogen gas supplied to the chamber 6 and the exhaust flow rate from the chamber 6 are made equal to maintain the pressure in the chamber 6 at the normal pressure Ps. .

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 turned on all at once to start preheating (assist heating) of the semiconductor wafer W. . Halogen light emitted from the halogen lamp HL passes through the lower chamber window 64 and the susceptor 74 made of quartz and is irradiated from the back surface of the semiconductor wafer W. As shown in FIG. The back surface of the semiconductor wafer W is the main surface opposite to the surface on which the metal film 108 is formed. The temperature of the semiconductor wafer W rises by receiving light irradiation from the halogen lamps HL. Since the transfer arm 11 of the transfer mechanism 10 is retracted inside the recess 62, it does not interfere with the heating by the halogen lamp HL.

The temperature of the semiconductor wafer W is measured by the contact thermometer 130 when preheating is performed by the halogen lamp HL. That is, a contact thermometer 130 containing a thermocouple is brought into contact with the lower surface of the semiconductor wafer W held by the susceptor 74 through the notch 77 to measure the wafer temperature during heating. The measured temperature of the semiconductor wafer W is transmitted to the controller 3 . The control unit 3 controls the output of the halogen lamps HL while monitoring whether the temperature of the semiconductor wafer W, which is heated by light irradiation from the halogen lamps HL, has reached a predetermined preheating temperature T1. That is, the control unit 3 feedback-controls the output of the halogen lamp HL based on the measured value by the contact thermometer 130 so that the temperature of the semiconductor wafer W reaches the preheating temperature T1. The preheating temperature T1 is room temperature or higher and 300° C. or lower, and is 200° C. in this embodiment. When the temperature of the semiconductor wafer W is raised by light irradiation from the halogen lamp HL, temperature measurement by the radiation thermometer 120 is not performed. This is because the halogen light emitted from the halogen lamp HL enters the radiation thermometer 120 as ambient light, making it impossible to accurately measure the temperature.

After the temperature of the semiconductor wafer W reaches the preheating temperature T1, the controller 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 bring the temperature of the semiconductor wafer W to approximately It is maintained at the preheating temperature T1.

By performing such preheating with the halogen lamp HL, the temperature of the entire semiconductor wafer W including the metal film 108 is uniformly raised to the preheating temperature T1. In the stage of preheating by the halogen lamps HL, the temperature of the peripheral portion of the semiconductor wafer W, where heat is more likely to be released, tends to be lower than that of the central portion. The region facing the peripheral portion of the semiconductor wafer W is higher than the region facing the central portion. For this reason, the amount of light irradiated to the peripheral portion of the semiconductor wafer W, which tends to cause heat dissipation, is increased, and the in-plane temperature distribution of the semiconductor wafer W in the preheating stage can be made uniform. Furthermore, since the inner peripheral surface of the reflecting ring 69 attached to the chamber side portion 61 is mirror-finished, the amount of light reflected toward the peripheral portion of the semiconductor wafer W by the inner peripheral surface of the reflecting ring 69 increases. The in-plane temperature distribution of the semiconductor wafer W in the preheating stage can be made more uniform. The pressure inside the chamber 6 during preheating is maintained at normal pressure Ps.

Next, at time t5 when the temperature of the semiconductor wafer W reaches the preheating temperature T1 and a predetermined time has elapsed, a flash heating process is performed by irradiating flash light from the flash lamps FL. At this time, part of the flash light emitted from the flash lamp FL goes directly into the chamber 6, and the other part is once reflected by the reflector 52 and then goes into the chamber 6. Flash heating of the semiconductor wafer W is effected by irradiation.

Since the flash heating is performed by irradiating flash light (flash light) from the flash lamps FL, the surface temperature of the semiconductor wafer W can be raised in a short time. That is, the flash light emitted from the flash lamp FL has an extremely short irradiation time of about 0.1 millisecond or more and 100 millisecond or less, in which the electrostatic energy previously stored in the capacitor is converted into an extremely short light pulse. A strong flash. By irradiating the surface of the semiconductor wafer W on which the metal film 108 is formed with flash light from the flash lamps FL, silicon in the source/drain regions reacts with the metal film 108 to form silicide (nickel silicide in this embodiment). is formed.

The processing temperature T2, which is the maximum temperature (peak temperature) reached by the surface of the semiconductor wafer W due to flash light irradiation, is 600° C. or higher and 1100° C. or lower at which silicide grows, and is set to 900° C. in this embodiment. Since the irradiation time from the flash lamps FL is short, approximately 0.1 millisecond or more and 100 milliseconds or less, the surface temperature of the semiconductor wafer W rises from the preheating temperature T1 to the processing temperature T2. The required time is also extremely short, less than 1 second. The surface temperature of the semiconductor wafer W after flash light irradiation immediately and rapidly drops from the processing temperature T2.

The halogen lamp HL is also extinguished after a predetermined time has elapsed after the flash heating process is completed. As a result, the temperature of the semiconductor wafer W is also lowered from the preheating temperature T1. The temperature of semiconductor wafer W during cooling is measured by contact thermometer 130 or radiation thermometer 120 , and the measurement result is transmitted to control unit 3 . The control unit 3 monitors whether the temperature of the semiconductor wafer W has decreased to a predetermined temperature based on the measurement result. After the temperature of the semiconductor wafer W is lowered to a predetermined level or less, the pair of transfer arms 11 of the transfer mechanism 10 moves horizontally again from the retracted position to the transfer operation position, thereby moving the lift pins 12 to the susceptor. It protrudes from the upper surface of 74 and receives the semiconductor wafer W after heat treatment from the susceptor 74 . Subsequently, the transfer opening 66 closed by the gate valve 185 is opened, the semiconductor wafer W placed on the lift pins 12 is transferred out by the transfer robot outside the apparatus, and the semiconductor wafer W is heat-treated in the heat treatment apparatus 1. is completed.

In the first embodiment, the pressure inside the chamber 6 is once reduced to the pressure P1 lower than the atmospheric pressure, and then the nitrogen gas is supplied to restore the pressure to the normal pressure Ps. It can be about 200 ppb or less. When the atmosphere is replaced with nitrogen gas while maintaining the normal pressure without reducing the pressure in the chamber 6, the limit of reducing the oxygen concentration in the chamber 6 is about 2 ppm. That is, as in the present embodiment, by reducing the pressure in the chamber 6 to the atmospheric pressure P1 and then restoring the pressure to the normal pressure Ps, the oxygen concentration in the chamber 6 is reduced to 1/10 compared to the case where the pressure is not reduced. It can be reduced to a degree.

After the metal film 108 is formed on the source/drain regions of the silicon base material 101, many defects are formed in the vicinity of the interface between the metal film 108 and the silicon base material 101 without special treatment. Existing. If heat treatment for silicide formation is performed while the oxygen concentration around the semiconductor wafer W is high, oxygen in the atmosphere enters defects near the interface between the metal film 108 and the substrate 101, resulting in deterioration of the vicinity of the interface and high resistance. becomes. Also, nickel silicide itself may be oxidized. Oxygen remaining in the chamber 6 is particularly problematic as a cause of such oxidation. When the semiconductor wafer W is carried into the chamber 6 under normal pressure as in this embodiment, a large amount of air is drawn in from the outside, which increases the residual oxygen concentration in the chamber 6 . Therefore, when the semiconductor wafer W with the metal film 108 formed thereon is heated to form silicide, it is preferable to reduce the oxygen concentration in the atmosphere as much as possible.

In the first embodiment, the oxygen concentration in the heat treatment space 65 in the chamber 6 when forming silicide is reduced to It is reduced to about 200 ppb or less. Therefore, it is possible to suppress the resistance of silicide from increasing due to oxygen in the heat treatment space 65 entering defects near the interface between the metal film 108 and the substrate 101 during the silicide forming process. In addition, oxidation of silicide itself can also be prevented.

In addition, since silicide is required to be formed as thin as possible, in the first embodiment, the surface of the semiconductor wafer W is irradiated with flash light from the flash lamps FL for an irradiation time of less than 1 second. Since the temperature of the wafer surface is raised to the processing temperature T2 in an extremely short time, it is possible to suppress excessive increase in the film thickness of the silicide.

In addition, if the flow rate of the nitrogen gas supplied is increased when the semiconductor wafer W is carried into the chamber 6 so that the nitrogen gas is caused to flow out from the transfer opening 66, the inflow of external air during the wafer carrying is prevented, and the inside of the chamber 6 before processing is prevented. can lower the initial value of oxygen concentration. As a result, the residual oxygen concentration can be made sufficiently low even if the atmospheric pressure P1, which is the ultimate pressure when reducing the pressure in the chamber 6, is high.

Furthermore, as described above, when the chamber 6 is decompressed, the exhaust is performed at a low exhaust flow rate at the start of depressurization, and then the exhaust flow is switched to a high exhaust flow rate. Winding up can be prevented.

<Second embodiment>
Next, a second embodiment of the invention will be described. The configuration of the heat treatment apparatus 1 of the second embodiment is exactly the same as that of the first embodiment. Further, the processing procedure 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 the pressure when the inside of the chamber 6 is once depressurized and then restored.

FIG. 11 is a diagram showing pressure changes within the chamber 6 in the second embodiment. In FIG. 11 as well, as in FIG. 10 , the horizontal axis indicates time, and the vertical axis indicates the pressure inside the chamber 6 . Also, the dotted line in FIG. 11 shows the pressure change pattern when the pressure inside the chamber 6 in the first embodiment is restored to normal pressure Ps (pattern in FIG. 10).

As in the first embodiment, when the semiconductor wafer W with the metal film 108 formed thereon is housed 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). Then, pressure reduction in the chamber 6 is started at time t1. As in the first embodiment, exhaust is performed with a small exhaust flow rate in the initial stage of decompression, and then at time t2, exhaust is performed with a larger exhaust flow rate. As a result, it is possible to prevent particles from being stirred up inside the chamber 6 .

At time t3 when the pressure in the chamber 6 reaches the atmospheric pressure P1, the valve 89 for exhaust is closed and the valve 84 for air supply is opened, and nitrogen is supplied from the gas supply source 85 to the heat treatment space 65 in the chamber 6. Supply gas. The process up to this point is the same as in the first embodiment. Incidentally, the atmospheric pressure P1 is, for example, approximately 100 Pa.

In the second embodiment, the pressure in the chamber 6 is restored to the atmospheric pressure P2 at time t6 by supplying nitrogen gas without restoring the pressure in the chamber 6 to the normal pressure Ps. The atmospheric pressure P2 is higher than the atmospheric pressure P1 and lower than the normal pressure Ps, eg, about 5000 Pa. Also in the second embodiment, the pressure inside the chamber 6 is once reduced to the atmospheric pressure P1 and then restored to the higher atmospheric pressure P2. can be done.

After time t6 when the pressure inside the chamber 6 returns to the atmospheric pressure P2, the flow rate of the nitrogen gas supplied to the chamber 6 and the exhaust flow rate from the chamber 6 are made equal to maintain the pressure inside the chamber 6 at the atmospheric pressure P2. Then, while maintaining the pressure in the chamber 6 at the atmospheric pressure P2, the semiconductor wafer W is preheated by the halogen lamp HL. Heat up. The contents of preheating and flash heat treatment are the same as in the first embodiment. By irradiating the surface of the semiconductor wafer W on which the metal film 108 is formed with flash light from the flash lamps FL, silicon in the source/drain regions reacts with the metal film 108 to form silicide.

After the completion of the flash heat treatment, the exhaust valve 89 is closed after a predetermined time has elapsed, the air supply valve 84 is opened, nitrogen gas is supplied from the gas supply source 85 into the chamber 6, and the pressure is maintained at normal pressure Ps. pressure is restored to Further, the halogen lamp HL is also turned off, whereby the temperature of the semiconductor wafer W is also lowered from the preheating temperature T1. After that, the procedure for unloading the semiconductor wafer W cooled down to the predetermined temperature from the chamber 6 of the heat treatment apparatus 1 is the same as in the first embodiment.

By the way, in addition to air supply/exhaust to/from the chamber 6, flash light irradiation also exists as a factor causing particles to roll up in the chamber 6. FIG. When the flash light is irradiated from the flash lamp FL, the temperature of the front surface of the semiconductor wafer W rises instantaneously while the temperature of the back surface of the semiconductor wafer W does not rise significantly from the preheating temperature T1. The only thermal expansion causes the semiconductor wafer W to deform abruptly. As a result, when the semiconductor wafer W vibrates on the susceptor 74 , particles are generated and swirled up in the chamber 6 .

In order to effectively discharge particles caused by such flash light irradiation from the chamber 6, in the second embodiment, after the flash heat treatment is finished, nitrogen gas is supplied into the chamber 6 to restore the pressure to the normal pressure Ps. At this time, the valve 89 for exhaust is opened, and nitrogen gas is caused to flow into the chamber 6 at a flow rate of 50 liters/minute or more and 100 liters/minute or less, thereby sweeping away the particles caused by the flash light irradiation. . As a result, it is possible to prevent the semiconductor wafer W from being contaminated by particles caused by flash light irradiation.

After the flash heating is completed, when nitrogen gas is supplied into the chamber 6 to restore the pressure to the normal pressure Ps, the valve 84 for air supply is opened while the valve 89 for exhaust is opened. may be supplied with nitrogen gas. In this way, particles caused by flash light irradiation can be discharged from the chamber 6 more effectively.

In the second embodiment, the inside of the chamber 6 is once depressurized to the pressure P1 lower than the atmospheric pressure, and then nitrogen gas is supplied to restore the pressure to the pressure P2. The oxygen concentration in the heat treatment space 65 in the chamber 6 can be set to about 200 ppb or less. Therefore, it is possible to suppress the resistance of silicide from increasing due to oxygen in the heat treatment space 65 entering defects near the interface between the metal film 108 and the substrate 101 during the silicide forming process. In addition, oxidation of silicide itself can also be prevented.

Further, as in the first embodiment, the surface of the semiconductor wafer W is irradiated with flash light from the flash lamps FL for an irradiation time of less than 1 second, and the temperature of the wafer surface is raised to the processing temperature T2 in an extremely short time. Therefore, excessive increase in the film thickness of silicide can be suppressed.

Further, if the heat treatment is performed under reduced pressure, desorption of impurities contained in the metal film 108 can be promoted. By discharging such detached impurity elements from the chamber 6, it is possible to prevent the impurities from reattaching to the surface of the semiconductor wafer W and contaminating it. As a result, it is possible to prevent deterioration of device performance and decrease in yield.

In addition, since the atmospheric gas in the chamber 6 absorbs less light from the halogen lamp and flash light, it is possible to increase the efficiency of temperature rise during preheating and flash heating. As a result, the surface temperature of the semiconductor wafer W during flash heating can be increased.

Moreover, 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.

Furthermore, in the second embodiment, when the pressure in the chamber 6 is restored from the atmospheric pressure P1, it is restored to the atmospheric pressure P2, which is lower than the atmospheric pressure, without being restored to the normal pressure Ps. Therefore, compared to restoring the pressure in the chamber 6 to the normal pressure Ps as in the first embodiment, if the pressure in the chamber 6 is restored to the atmospheric pressure P2 as in the second embodiment, the time required for the restoration is can be shortened. Then, the timing of flash light irradiation can be advanced by the shortened time required for pressure recovery (as shown in FIG. 11, the flash light irradiation time t5 in the second embodiment is earlier than the flash light irradiation time t5 in the first embodiment). The light irradiation time t7 is early). As a result, the throughput in the heat treatment apparatus 1 can be improved by restoring the pressure in the chamber 6 to the pressure P2 lower than the atmospheric pressure as in the second embodiment.

<Third Embodiment>
Next, a third embodiment of the invention will be described. The configuration of the heat treatment apparatus 1 of the third embodiment is exactly the same as that of the first embodiment. Further, the processing procedure 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 the change in pressure within the chamber 6 .

FIG. 12 is a diagram showing pressure changes in the chamber 6 in the third embodiment. In FIG. 12 as well, as in FIG. 10 , the horizontal axis indicates time, and the vertical axis indicates the pressure inside the chamber 6 .

As in the first embodiment, when the semiconductor wafer W with the metal film 108 formed thereon is housed 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). Then, pressure reduction in the chamber 6 is started at time t1. In the third embodiment, the exhaust flow rate through the three bypass lines 197, 198, 199 is kept constant, and the exhaust flow rate from the chamber 6 is continuously increased over time by the flow control valve 196. FIG. That is, in the initial stage of depressurization, exhaust is started with a relatively small exhaust flow rate, and the exhaust flow rate is gradually increased continuously. By doing so, it is possible to prevent particles from being stirred up in the chamber 6, as in the first embodiment. In addition, by increasing the exhaust flow rate steplessly and continuously, it is possible to prevent particles from being stirred up due to a sudden change in the exhaust flow rate.

At time t3 when the pressure in the chamber 6 reaches the atmospheric pressure P1, the valve 89 for exhaust is closed and the valve 84 for air supply is opened, and nitrogen is supplied from the gas supply source 85 to the heat treatment space 65 in the chamber 6. Gas is supplied to restore the pressure in the chamber 6 . Incidentally, the atmospheric pressure P1 is, for example, approximately 100 Pa.

In the third embodiment, the flow rate of the processing gas supplied to the chamber 6 is continuously increased over time by the flow control valve 90 . That is, in the initial stage of pressure recovery, air supply is started with a relatively small air supply flow rate, and the air supply flow rate is gradually increased continuously. As in the case of depressurization, if air is rapidly supplied at a high supply flow rate from the start of pressure recovery, particles adhering to the structure of the chamber 6 may be stirred up. In the initial stage of pressure recovery, air supply is quietly started with a small air supply flow rate, and the exhaust flow rate is gradually increased, thereby preventing such particles from being stirred up in the chamber 6 . Further, by increasing the supply air flow rate steplessly and continuously, it is possible to prevent particles from being stirred up due to a sudden change in the supply air flow rate.

In the third embodiment, nitrogen gas is supplied to the chamber 6 to restore the pressure in the chamber 6 to the atmospheric pressure P3 exceeding the normal pressure Ps at time t8. The atmospheric pressure P3 is higher than the atmospheric pressure and is, for example, approximately 0.12 MPa. In the third embodiment as well, the pressure inside the chamber 6 is once reduced to the atmospheric pressure P1 and then restored to the higher atmospheric pressure P3, so the oxygen concentration in the chamber 6 after the pressure is restored should be about 200 ppb or less. can be done.

After time t8 when the pressure inside the chamber 6 returns to the atmospheric pressure P3, the flow rate of the nitrogen gas supplied to the chamber 6 and the exhaust flow rate from the chamber 6 are made equal to maintain the pressure inside the chamber 6 at the atmospheric pressure P3. Then, while maintaining the pressure in the chamber 6 at the atmospheric 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 irradiated with flash light from the flash lamp FL to flash. Heat up. The contents of preheating and flash heat treatment are the same as in the first embodiment. By irradiating the surface of the semiconductor wafer W on which the metal film 108 is formed with flash light from the flash lamps FL, silicon in the source/drain regions reacts with the metal film 108 to form silicide.

After the flash heat treatment is finished, the gas inside the chamber 6 is discharged from the gas exhaust pipe 88 to make the inside of the chamber 6 normal pressure Ps. Further, the halogen lamp HL is also turned off, whereby the temperature of the semiconductor wafer W is also lowered from the preheating temperature T1. After that, the procedure for unloading the semiconductor wafer W cooled down to the predetermined temperature from the chamber 6 of the heat treatment apparatus 1 is the same as in the first embodiment.

In the third embodiment, the inside of the chamber 6 is once depressurized to the pressure P1 lower than the atmospheric pressure, and then nitrogen gas is supplied to restore the pressure to the pressure P3. The oxygen concentration in the heat treatment space 65 in the chamber 6 can be set to about 200 ppb or less. Therefore, it is possible to suppress the resistance of silicide from increasing due to oxygen in the heat treatment space 65 entering defects near the interface between the metal film 108 and the substrate 101 during the silicide forming process. In addition, oxidation of silicide itself can also be prevented.

Further, as in the first embodiment, the surface of the semiconductor wafer W is irradiated with flash light from the flash lamps FL for an irradiation time of less than 1 second, and the temperature of the wafer surface is raised to the processing temperature T2 in an extremely short time. Therefore, excessive increase in the film thickness of silicide can be suppressed.

Further, in the third embodiment, the surface of the semiconductor wafer W is irradiated with flash light to perform the heat treatment at the pressure P3 in which the pressure in the chamber 6 is higher than the atmospheric pressure, that is, under pressure. If the heat treatment is performed under pressure, the diffusion speed of oxygen released from the chamber side portion 61 or the like is slowed down, and it is possible to suppress the oxygen from reaching the semiconductor wafer W. FIG.

Furthermore, in the third embodiment, the exhaust gas flow rate and the supply air flow rate are changed steplessly and continuously during depressurization and restoration of the chamber 6 . As a result, it is possible to prevent particles from being stirred up due to sudden changes in air supply and exhaust.

<Fourth Embodiment>
Next, a fourth embodiment of the invention will be described. The configuration of the heat treatment apparatus 1 of the fourth embodiment is exactly the same as that of the first embodiment. Further, the processing procedure of the semiconductor wafer W in the heat treatment apparatus 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 change in pressure within the chamber 6 .

FIG. 13 is a diagram showing pressure changes within the chamber 6 in the fourth embodiment. In FIG. 13 as well, as in FIG. 10 , the horizontal axis indicates time, and the vertical axis indicates the pressure inside the chamber 6 .

As in the first embodiment, when the semiconductor wafer W with the metal film 108 formed thereon is housed 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). Then, pressure reduction in the chamber 6 is started at time t1. As in the first embodiment, exhaust is performed with a small exhaust flow rate in the initial stage of decompression, and then at time t2, exhaust is performed with a larger exhaust flow rate. As a result, it is possible to prevent particles from being stirred up inside the chamber 6 .

At time t3 when the pressure in the chamber 6 reaches the atmospheric pressure P1, the valve 89 for exhaust is closed. Then, in the fourth embodiment, the pressure inside the chamber 6 is maintained at the atmospheric pressure P1 without introducing nitrogen gas into the chamber 6 . In order to maintain the pressure in the chamber 6 at the atmospheric pressure P1, the valve 89 may be opened to continue the evacuation.

In the fourth embodiment, the pressure inside the chamber 6 is reduced to the atmospheric pressure P1 and the atmospheric pressure P1 is maintained thereafter, so that the residual oxygen concentration inside the chamber 6 can be reduced to approximately 200 ppb or less. Then, while maintaining the pressure in the chamber 6 at the atmospheric pressure P1, the semiconductor wafer W is preheated by the halogen lamp HL, and then at time t10, the surface of the semiconductor wafer W is irradiated with flash light from the flash lamp FL to flash. Heat up. The contents of preheating and flash heat treatment are the same as in the first embodiment. By irradiating the surface of the semiconductor wafer W on which the metal film 108 is formed with flash light from the flash lamps FL, silicon in the source/drain regions reacts with the metal film 108 to form silicide.

After the completion of the flash heat treatment, the valve 84 for air supply is opened after a predetermined time has elapsed, and nitrogen gas is supplied from the gas supply source 85 into the chamber 6 to restore the pressure to the normal pressure Ps. Further, the halogen lamp HL is also turned off, whereby the temperature of the semiconductor wafer W is also lowered from the preheating temperature T1. After that, the procedure for unloading the semiconductor wafer W cooled down to the predetermined temperature from the chamber 6 of the heat treatment apparatus 1 is the same as in the first embodiment.

In the fourth embodiment, the pressure in the chamber 6 is reduced to the pressure P1 which is lower than the atmospheric pressure, and then the pressure is maintained at the pressure P1. The oxygen concentration in the heat treatment space 65 can be about 200 ppb or less. Therefore, it is possible to suppress the resistance of silicide from increasing due to oxygen in the heat treatment space 65 entering defects near the interface between the metal film 108 and the substrate 101 during the silicide forming process. In addition, oxidation of silicide itself can also be prevented.

Further, as in the first embodiment, the surface of the semiconductor wafer W is irradiated with flash light from the flash lamps FL for an irradiation time of less than 1 second, and the temperature of the wafer surface is raised to the processing temperature T2 in an extremely short time. Therefore, excessive increase in the film thickness of silicide can be suppressed.

Further, by performing the heat treatment of the semiconductor wafer W under reduced pressure, the same effect as in the second embodiment can be obtained. Furthermore, when the metal film 108 is titanium, the metal film 108 may be nitrided even if the heat treatment is performed in a nitrogen atmosphere. Nitriding of the metal film 108 can be suppressed by heat treatment.

<Modification>
Although the embodiments of the present invention have been described above, the present invention can be modified in various ways other than those described above without departing from the scope of the invention. For example, in each of the above-described embodiments, the air pressure P1, which is the ultimate pressure when reducing the pressure in the chamber 6, is set to about 100 Pa, but it is not limited to this and can be set to an appropriate value. In order to reduce the ultimate oxygen concentration in the chamber 6 to about 1/10, if the ultimate pressure P1, which is the ultimate pressure when reducing the pressure in the chamber 6, is about 1/10 of the atmospheric pressure (about 10000 Pa), Enough. If the atmospheric pressure P1 is made lower (that is, if the pressure is reduced to a higher vacuum), the concentration of oxygen remaining in the chamber 6 after the pressure is restored can be made lower. Longer decompression time. For this reason, it is preferable to set the air pressure P1 according to the balance between the oxygen concentration and the throughput required when performing the heat treatment for silicide formation.

In each of the above-described embodiments, the flow rate of exhaust gas from the chamber 6 is controlled by providing three bypass lines 197, 198, 199, but the number of bypass lines may be two or more. Further, instead of providing a plurality of bypass lines 197, 198, 199, a throttle valve or gas ballast may be provided to control the flow rate of exhaust gas from the chamber 6. Also, a mass flow controller may be used instead of the flow rate control valves 90 and 196 .

In the first and second embodiments, the exhaust flow rate from the chamber 6 during decompression was switched in two steps, and in the third embodiment, the exhaust flow rate was steplessly and continuously increased, but the invention is not limited to these. Instead, for example, the exhaust flow rate may be switched in multiple stages. In other words, it is sufficient that the flow rate of the exhaust gas when reducing the pressure in the chamber 6 increases with time.

Similarly, with respect to the air supply flow rate to the chamber 6 during pressure recovery, the air supply flow rate is increased steplessly and continuously in the third embodiment, but this is switched in two steps or in multiple steps to increase. You can do it. In other words, it is sufficient that the air supply flow rate when the pressure inside the chamber 6 is restored increases with time.

Further, 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). Various valves and the like may be feedback-controlled based on the measurement result of the pressure in the heat treatment space 65. When the control is performed based on the elapsed time, the relationship between the elapsed time and the pressure inside the chamber 6 may be obtained by experiments or simulations.

In each of the above embodiments, the metal film 108 is formed on the base material 101 of silicon to form silicide, but the material of the base material 101 is not limited to silicon. ) or silicon germanium. In particular, silicon germanium is used as substrate 101 when manufacturing PMOS transistors. When the base material 101 is germanium or silicon germanium, a metal film 108 is formed on the base material 101, and germanium reacts with the metal to form germanide. Even if the base material 101 is germanium or silicon-germanium, the processing of the semiconductor wafer W is the same as in the above embodiments.

Moreover, although each of the above-described embodiments suppresses an increase in the resistance of silicide, the technology according to the present invention can also be applied to reduce the contact resistance in the Fin structure. In the Fin structure, a metal film (for example, a TiN film) for contact formation is deposited on a partial region (contact hole opening) of the base material 101 . Contact resistance can be reduced by applying the technique of the present invention to form a contact (ohmic contact) between the metal film and the substrate 101 and performing heat treatment at an extremely low oxygen concentration.

In each of the above embodiments, the flash heating unit 5 is provided with 30 flash lamps FL, but the number of flash lamps FL is not limited to this, and the number of flash lamps FL can be set to any number. can. Also, the flash lamp FL is not limited to a xenon flash lamp, and may be a krypton flash lamp. Also, the number of halogen lamps HL provided in the halogen heating unit 4 is not limited to 40, and may be any number as long as a plurality of lamps are arranged in the upper and lower stages.

In the above embodiment, the semiconductor wafer W is preheated by irradiating halogen light from the halogen lamps HL, but the method of preheating is not limited to this. The semiconductor wafer W may be preheated by heating.

REFERENCE SIGNS LIST 1 heat treatment apparatus 3 control section 4 halogen heating section 5 flash heating section 6 chamber 7 holding section 10 transfer mechanism 61 chamber side section 63 upper chamber window 64 lower chamber window 65 heat treatment space 74 susceptor 85 gas supply source 90, 196 flow rate adjustment Bulb 101 Base material 102 Silicon oxide film 103 High dielectric constant film 105 Gate electrode 108 Metal film 190 Exhaust part 191 Exhaust pump 192, 193, 194 Exhaust valve 197, 198, 199 Bypass line FL Flash lamp HL Halogen lamp W Semiconductor wafer

Claims (11)

A heat treatment method for forming a contact by irradiating a substrate with flash light,
a carrying-in step of carrying the substrate on which the metal film is formed into the chamber;
a depressurization step of depressurizing the chamber to a first pressure lower than atmospheric pressure;
a pressure restoring step of restoring the pressure in the chamber from a first pressure to a second pressure higher than the first pressure;
an irradiation step of irradiating the surface of the substrate with flash light from a flash lamp while maintaining the inside of the chamber at a second pressure;
with
the second pressure is greater than the first pressure and less than atmospheric pressure;
In the pressure recovery step, the oxygen concentration in the chamber after pressure recovery is set to 200 ppb or less,
After the irradiation step, when the inert gas is supplied into the chamber to restore the pressure in the chamber to atmospheric pressure, the valve for air supply is opened while the valve for exhaust is open. A heat treatment method characterized by: In the heat treatment method according to claim 1,
A heat treatment method, wherein in the depressurization step, a flow rate of exhaust gas from the chamber is increased with time. In the heat treatment method according to claim 1 or claim 2,
A heat treatment method, wherein, in the pressure recovery step, a flow rate of air supplied to the chamber is increased with time. In the heat treatment method according to any one of claims 1 to 3,
A heat treatment method, characterized in that, after the irradiation step, an inert gas is caused to flow into the chamber at a flow rate of 50 liters/minute or more and 100 liters/minute or less with the inside of the chamber being atmospheric pressure. In the heat treatment method according to any one of claims 1 to 4,
The heat treatment method, wherein in the carrying-in step, an inert gas is supplied into the chamber while opening a carrying opening of the chamber. A heat treatment method for forming a contact by irradiating a substrate with flash light,
a carrying-in step of carrying the substrate on which the metal film is formed into the chamber;
a depressurization step of depressurizing the chamber to a first pressure lower than atmospheric pressure;
an irradiation step of irradiating the surface of the substrate with flash light from a flash lamp while maintaining the inside of the chamber at a first pressure;
with
In the pressure reduction step, the oxygen concentration in the chamber is set to 200 ppb or less,
After the irradiation step, when the inert gas is supplied into the chamber to restore the pressure in the chamber to atmospheric pressure, the valve for air supply is opened while the valve for exhaust is open. A heat treatment method characterized by: A heat treatment apparatus for forming a contact by irradiating a substrate with flash light,
a chamber containing a substrate on which a metal film is formed;
a flash lamp for irradiating the substrate housed in the chamber with flash light;
an exhaust unit for exhausting the atmosphere in the chamber;
a gas supply unit that supplies a predetermined processing gas to the chamber;
After reducing the pressure in the chamber to a first pressure lower than the atmospheric pressure, the surface of the substrate is irradiated with flash light from the flash lamp while the pressure is restored to a second pressure higher than the first pressure. a control unit that controls the exhaust unit and the gas supply unit such that
with
the second pressure is greater than the first pressure and less than atmospheric pressure;
setting the oxygen concentration in the chamber after the pressure in the chamber is restored to the second pressure to 200 ppb or less;
After the irradiation of the flash light, the control unit supplies the inert gas into the chamber to restore the pressure in the chamber to the atmospheric pressure, the gas supply unit keeps the valve of the exhaust unit open. A heat treatment apparatus characterized in that the valve is also opened. In the heat treatment apparatus according to claim 7,
The heat treatment apparatus, wherein the control unit controls the exhaust unit so that the exhaust flow rate from the chamber increases with time when the pressure inside the chamber is reduced to the first pressure. In the heat treatment apparatus according to claim 7 or claim 8,
The control unit controls the gas supply unit so that the flow rate of air supplied to the chamber increases with time when the pressure inside the chamber is restored from the first pressure to the second pressure. Heat treatment equipment. In the heat treatment apparatus according to any one of claims 7 to 9,
After irradiation with the flash light, the control unit controls the exhaust unit and the gas so that an inert gas flows into the chamber at a flow rate of 50 liters/minute or more and 100 liters/minute or less with the inside of the chamber being atmospheric pressure. A heat treatment apparatus characterized by controlling a supply unit. A heat treatment apparatus for forming a contact by irradiating a substrate with flash light,
a chamber containing a substrate on which a metal film is formed;
a flash lamp for irradiating the substrate housed in the chamber with flash light;
an exhaust unit for exhausting the atmosphere in the chamber;
a gas supply unit that supplies a predetermined processing gas to the chamber;
After reducing the pressure in the chamber to a first pressure lower than the atmospheric pressure, the evacuation unit and the gas supply are performed so that the surface of the substrate is irradiated with flash light from the flash lamp while maintaining the first pressure. a control unit that controls the unit;
with
After reducing the pressure in the chamber to the first pressure, the oxygen concentration in the chamber is 200 ppb or less,
After the irradiation of the flash light, the control unit supplies the inert gas into the chamber to restore the pressure in the chamber to the atmospheric pressure, the gas supply unit keeps the valve of the exhaust unit open. A heat treatment apparatus characterized in that the valve is also opened.

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