CN116741621A - Substrate processing method and substrate processing system - Google Patents

Abstract

The present invention provides a substrate processing method and a substrate processing system that prevent or at least suppress damage to a pattern formed on the surface of a substrate during supercritical drying. The substrate processing method includes: a degassing step to remove dissolved gas in the treatment liquid; and a liquid film forming step to supply the treatment liquid from which the dissolved gas has been removed to the surface of the substrate to form a film covering the surface of the substrate. a liquid film of the processing liquid; a loading step of loading the substrate on which the liquid film is formed into a processing container; and a supercritical drying step of loading the substrate on which the liquid film is formed The pressure in the processing container is maintained at a pressure that maintains the processing fluid in a supercritical state, and the processing fluid is circulated into the processing container, whereby the processing fluid covering the surface of the substrate is replaced. processing fluid, and then drying the surface of the substrate by vaporizing the processing fluid.

Description

Substrate processing method and substrate processing system

Technical field

The present disclosure relates to a substrate processing method and a substrate processing system.

Background technique

In the manufacturing process of a semiconductor device for forming a stacked structure of an integrated circuit on the surface of a semiconductor wafer (hereinafter referred to as a wafer) as a substrate, a treatment process of treating the wafer surface with a liquid is performed, for example, by Cleaning fluids such as chemical solutions are used to remove tiny dust, natural oxide films, etc. on the wafer surface.

There is known a method of using a processing fluid in a supercritical state when removing liquid remaining on the surface of a wafer through such a processing step. For example, Patent Document 1 discloses a substrate processing apparatus that uses a supercritical fluid to dissolve an organic solvent from a substrate and dry the wafer.

In the substrate processing apparatus of Patent Document 1, the surface of the wafer is cleaned with a cleaning liquid such as a chemical solution in the processing apparatus. An organic solvent serving as a treatment liquid is placed on the surface of the cleaned wafer. The wafer containing the organic solvent is transferred from the cleaning device to the supercritical processing device, and in the supercritical processing device, the wafer is dried using a processing fluid in a supercritical state. By placing an organic solvent on the surface of the wafer in this way, the surface of the cleaned wafer is prevented from drying before being dried in the supercritical processing apparatus, thereby preventing the generation of particles.

existing technical documents

patent documents

Patent Document 1: Japanese Patent Application Publication No. 2019-33246

Contents of the invention

Invent the problem to be solved

The present disclosure provides a technology that can prevent or at least suppress damage to a pattern formed on the surface of a substrate when performing a supercritical drying process.

solutions to problems

A substrate processing method according to one embodiment of the present disclosure includes: a degassing step of removing dissolved gas in a treatment liquid; and a liquid film forming step of supplying the treatment liquid from which the dissolved gas has been removed to the surface of the substrate, to form a liquid film of the processing liquid covering the surface of the substrate; a loading step of loading the substrate with the liquid film formed into a processing container; and a supercritical drying step of loading the substrate with the liquid film formed thereon. The pressure in the processing container of the substrate of the liquid film is maintained at a pressure that maintains the processing fluid in a supercritical state, and the processing fluid is circulated into the processing container, whereby the processing fluid is used to The processing liquid covering the surface of the substrate is replaced, and then the surface of the substrate is dried by vaporizing the processing fluid.

Effect of the invention

According to the above-described embodiments of the present disclosure, it is possible to prevent or at least suppress damage to the pattern formed on the surface of the substrate when performing the supercritical drying process.

Description of drawings

FIG. 1 is a schematic cross-sectional view of a substrate processing system according to one embodiment of the substrate processing apparatus.

FIG. 2 is a schematic cross-sectional view showing a structural example of a single-chip liquid processing unit included in the substrate processing system of FIG. 1 .

FIG. 3 is a schematic cross-sectional view showing a structural example of a supercritical drying unit included in the substrate processing system of FIG. 1 .

4 is a piping structural diagram illustrating an IPA supply mechanism for supplying IPA used in the single-chip liquid processing unit of FIG. 2 and a structure for degassing provided in the IPA supply mechanism.

FIG. 5 is a schematic diagram showing damage to a pattern due to generation of bubbles.

Detailed ways

Next, the substrate processing system 1 according to one embodiment of the substrate processing apparatus of the present disclosure will be described with reference to the drawings. In order to simplify the explanation related to the direction, an XYZ orthogonal coordinate system is set and shown in the lower left part of FIG. 1 . The Z direction is the up and down direction, and the positive Z direction is the upward direction.

As shown in FIG. 1 , the substrate processing system 1 includes a control device 100 . The control device 100 is composed of a computer and includes a calculation processing unit 101 and a storage unit 102 . The storage unit 102 stores programs (including process recipes) for controlling various processes executed in the substrate processing system 1 . The arithmetic processing unit 101 reads and executes the program stored in the storage unit 102 to control the operation of each component of the substrate processing system 1 described below, and executes a series of processes described below. The control device 100 may be equipped with a user interface such as a keyboard, a touch panel, and a display. The above-described program can be recorded in a computer-readable storage medium and installed from the storage medium in the storage unit 102 of the control device 100 . Examples of storage media that can be read by a computer include a hard disk (HD), a flexible disk (FD), a compact disk (CD), a magneto-optical disk (MO), a memory card, and the like.

The substrate processing system 1 includes a loading/unloading unit (loading/unloading station) 2 and a processing unit (processing station) 6 .

The loading and unloading unit 2 includes a container placing unit 21 and a first conveying unit 22 . A plurality of substrate transfer containers C (for example, FOUP) can be placed on the container placement portion 21 . In each substrate transfer container C, a plurality of substrates W (for example, semiconductor wafers) are accommodated in a horizontal posture at intervals in the vertical direction.

The first conveyance section 22 is provided adjacent to the container placement section 21 . A first substrate transfer robot (first substrate transfer mechanism) 23 and a transfer unit (transfer unit) 24 are provided inside the first transfer unit 22 . The first substrate transfer robot 23 is provided with a substrate holding mechanism as an end effector for holding the substrate W. The first substrate transfer robot 23 can move in the horizontal direction and the vertical direction, and can rotate about the vertical axis. The first substrate transfer robot 23 transfers the substrate W between the substrate transfer container C on the container placement unit 21 and the transfer unit 24 .

The processing unit 6 is provided adjacent to the first conveyance unit 22 . The processing unit 6 is provided with one or more single-chip liquid processing units 61 , one or more supercritical drying units 62 that perform supercritical drying of the substrate W processed by the single-chip liquid processing unit 61 , and a second substrate transport. Robot (second substrate transport mechanism) 63 . In one embodiment, a plurality of monolithic liquid treatment units 61 and a plurality of supercritical drying units 62 may be stacked one above another at the position shown in FIG. 1 .

The second substrate transfer robot 63 includes an end effector that is movable by a multi-axis drive mechanism 631 that can move in the X and Y directions, lift in the Z direction, and rotate around a vertical axis. The end effector is, for example, a fork-shaped substrate holding device 632 capable of holding one substrate in a horizontal posture. The second substrate transfer robot 63 (especially its end effector) can transfer substrates between the transfer unit 24 , the single-wafer liquid processing unit 61 and the supercritical drying unit 62 by moving in the transfer space 64 . While being transported by the second substrate transport robot 63, the substrate W is always maintained in a horizontal posture.

A nitrogen gas supply unit 65 for ejecting nitrogen gas is provided in the transfer space 64 . Nitrogen gas is supplied to the nitrogen supply unit 65 from a nitrogen supply source provided as a site facility, for example. An exhaust unit 66 may be provided to discharge the atmosphere in the transfer space 64 to promote nitrogen purging in the transfer space 64 . From the viewpoint of improving purging efficiency, it is preferable to provide the nitrogen supply part 65 and the exhaust part 66 at positions separated from each other. The nitrogen supply part 65 schematically shown in FIG. 1 may be provided on the top wall of the rectangular parallelepiped-shaped transport space 64. In this case, the nitrogen supply part 65 forms a downward flow of nitrogen gas in the transport space 64. Alternatively, the nitrogen supply part 65 may be provided on the side wall of the transport space 64 . In this case, the nitrogen supply part 65 forms a flow of nitrogen gas in the transport space 64 .

A partition wall 67 is provided between the transfer space 64 of the processing unit 6 and the delivery unit 24 , and a door (not shown) having appropriate airtightness is provided in the partition wall 67 . This door (not shown) is opened only when the substrate W passes through the door. This structure can prevent the nitrogen gas from leaking from the transport space 64 to the first transport section 22 and thereby prevent the nitrogen gas from being wasted needlessly. It can also prevent the nitrogen gas from leaking from the transport space 64 to the surrounding environment of the substrate processing system 1 .

As the single-chip liquid processing unit 61, any single-chip liquid processing unit known in the technical field of semiconductor manufacturing equipment can be used. A structural example of the single-chip liquid processing unit 61 usable in this embodiment will be briefly described below with reference to FIG. 2 . The single-chip liquid processing unit 61 includes a spin chuck 611 capable of holding the substrate W in a horizontal position and rotating the substrate W around a vertical axis, and ejects the spin chuck 611 to the substrate W held and rotated by the spin chuck 611 . One or more nozzles 612 for treatment liquid. The nozzle 612 is supported by an arm 613 for moving the nozzle 612 . The single-chip liquid processing unit 61 has a liquid receiving cup 614 that collects the processing liquid scattered from the rotating substrate W. The liquid receiving cup 614 has a liquid discharge port 615 for discharging the collected processing liquid to the outside of the liquid processing unit 61 and an exhaust port 616 for discharging the atmospheric gas in the liquid receiving cup 614 . Clean gas is blown downward from the fan filter unit 618 provided at the top of the chamber 617 of the single-chip liquid processing unit 61 , and is introduced into the liquid receiving cup 614 and discharged to the exhaust port 616 .

As the fan filter unit 618, a fan filter unit having a function of selecting and ejecting one of clean air (clean air) and inert gas, for example, nitrogen gas ( _N2 gas) here, can be used. In this case, as clean air, clean air obtained by filtering the air in a clean room where the substrate processing system 1 is installed is used through a filter (for example, a ULPA filter) in the fan filter unit 618 , and as nitrogen, use is made from Nitrogen gas supplied from a nitrogen supply source provided as a facility for semiconductor manufacturing plants. The fan filter unit 618 having such a function is well known in the technical field of semiconductor manufacturing equipment, and a detailed description of the structure is omitted.

As the supercritical drying unit 62, any supercritical drying unit known in the technical field of semiconductor manufacturing equipment can be used. A structural example and operation of the supercritical drying unit 62 that can be used in this embodiment will be briefly described below with reference to FIGS. 1 and 3 . The supercritical drying unit 62 has a supercritical chamber 621 and a substrate support tray 622 that can move forward and backward with respect to the supercritical chamber 621 . FIG. 1 depicts the substrate support tray 622 exiting the supercritical chamber 621 . In this state, the second substrate transfer robot 63 can transfer the substrate W to the substrate support tray 622 .

FIG. 3 shows a state in which the substrate support tray 622 is housed in the supercritical chamber 621 . The substrate support tray 622 has a cover 625 , and the cover 625 closes the opening of the supercritical chamber 621 through a member (not shown), thereby forming a sealed processing space in the supercritical chamber 621 . Reference number 623 is a supply port 623 for a treatment fluid (for example, CO ₂ (carbon dioxide)), and reference 624 is an exhaust port for a fluid (CO ₂ , IPA, etc.).

The nitrogen gas ejection unit 626 can be provided in the supercritical drying unit 62 so that the area 628 in the supercritical drying unit 62 for transferring the substrate W to the substrate support tray 622 (the area where the substrate support tray 622 is present in FIG. 1 area) was set to a nitrogen atmosphere. An exhaust part 627 for exhausting the atmosphere in the area 628 may also be provided to promote nitrogen purging of the area 628. From the viewpoint of improving purging efficiency, it is preferable to provide the nitrogen supply part 626 and the exhaust part 627 at positions separated from each other.

Next, the IPA supply mechanism 700 for supplying IPA (isopropyl alcohol) used in the single-chip liquid processing unit 61 and the structure for degassing provided in the IPA supply mechanism 700 will be described with reference to FIG. 4 .

The IPA supply mechanism 700 has a tank 702 for storing IPA, and a circulation line 704 connected to the tank 702. In the circulation line 704, a pump 706, a thermostat 708, a filter 710, a flow meter 712, and a constant pressure valve 714 are provided in order from the upstream side. The pump 706 pressurizes IPA and sends it out, thereby forming a circulating flow of IPA in the circulation line 704 . The thermostat 708 adjusts the temperature of the IPA to a temperature suitable for use in the single-chip liquid processing unit 61 as the supply destination of the IPA. Filter 710 removes particulates and other contaminants from the IPA. The constant pressure valve 714 enables IPA to flow into the single-chip liquid processing unit 61 as the supply destination of IPA at an appropriate pressure.

A plurality of branch points 715 are set in the circulation line 704 , and a branch supply line 716 is branched from the circulation line 704 at each branch point 715 . The downstream end of each branch supply line 716 is connected to the IPA supply nozzle 612 of the corresponding single-chip liquid processing unit 61 . In the branch supply line 716, a dissolved gas monitor 718, a constant pressure valve 720, an on-off valve 722, and a dissolved gas filter (eg, a hollow fiber membrane filter) 724 are provided in this order from the upstream side. The branch return line 730 branches from the branch supply line 716 at a branch point 728 set in the branch supply line 716 . The branch return line 730 is provided with an on-off valve 732 . The plurality of branch return lines 730 merge to form one return line 734, and the downstream end of the return line 734 is connected to the tank 702.

The degassing line 742 branches from the branch point 740 set in the circulation line 704 . In the degassing line 742, an online megasonic device 744, an online dissolved gas monitor (dissolved gas sensor) 746, a constant pressure valve 748, and a hollow fiber membrane filter 750 are provided in this order from the upstream side. The downstream end of degassing line 742 is connected to tank 702 .

The online megasonic device 744 generates cavitation bubbles by applying high output ultrasonic waves to the IPA flowing in the degassing line 742 . The online dissolved gas monitor (dissolved gas sensor) 746 measures the concentration of gases contained in the IPA flowing in the degassing line 742, particularly oxygen, carbon dioxide, and the like, which are harmful gases to the processing described below. The constant pressure valve 748 regulates the flow rate of IPA flowing in the degassing line 742 .

The outside of the hollow fiber membrane of the hollow fiber membrane filter 750 is placed in a reduced pressure state. When IPA flows through the hollow fiber membrane, the bubbles contained in the IPA (which are cavitation bubbles generated by the online megasonic device 744) and The dissolved gas contained in the IPA passes through the wall of the hollow fiber membrane and comes to the outside of the hollow fiber membrane. Thereby, bubbles and dissolved gases in IPA can be reduced. Degassing can also be performed only by the hollow fiber membrane filter 750 . However, in this degassing line 742 , since the gas in the IPA has been bubbled by the online megasonic device 744 on the upstream side of the hollow fiber membrane filter 750 , compared with only passing through the hollow fiber membrane filter 750 , In the case of degassing, the removal efficiency of dissolved gases can be further improved. The IPA from which dissolved gases have been removed is returned to tank 702.

In the embodiment shown in FIG. 4 , the online degassing mechanism is composed of two online devices: an online megasonic device 744 and a hollow fiber membrane filter 750 . In addition, as described above, since degassing can be performed using only the hollow fiber membrane filter 750, an online degassing mechanism can also be configured using only the hollow fiber membrane filter 750. In addition, the online degassing mechanism refers to a mechanism that is installed in a line (a flow path for liquid such as pipes) and can degas a liquid while allowing the liquid to circulate through the mechanism (without stopping the flow of the liquid).

IPA is supplied to tank 702 from IPA supply source 760 via IPA supply line 762 . The IPA supply line 762 is provided with an on-off valve 764 . In many cases, the IPA supply source 760 is provided as a site facility of a semiconductor manufacturing factory where the substrate processing system 1 is installed. The tank 702 is connected to a discharge line 766, and the discharge line 766 is provided with an on-off valve 768.

In the first structural example of the IPA supply mechanism 700 , the tank 702 is connected to a supply source 780 of an inert gas (here, nitrogen gas) via a gas supply line 782 . An opening and closing valve 784 is connected to the gas supply line 782 . In most cases, nitrogen supply 780 is also provided as a site facility. In addition, the tank 702 is provided with a heater 790 . Furthermore, a cooler 726 is provided on the downstream side of the filter 724 in the branch supply line 716 . Use dashed or dotted lines to outline the components described in the paragraph.

In the second structural example of the IPA supply mechanism 700 , the tank 702 is connected to the vacuum pump (pressure reducing device) 770 via the pressure reducing line 772 . The pressure reducing line 772 is provided with an on-off valve 774 and a vacuum filter 776 . A discharge line 778 is connected to the pressure reducing line 772 .

The difference between the first structural example and the second structural example is only the above-mentioned part, and other structures are common between them.

Next, the operation of the IPA supply mechanism 700 in the first structural example will be described. Nitrogen gas is supplied to the tank 702 from the nitrogen supply source 780, and the inside of the tank 702 is made into a nitrogen atmosphere. This can prevent oxygen and carbon dioxide gas from dissolving into IPA. In addition, after IPA is supplied from the IPA supply source 760 to the tank 702 and a predetermined amount of IPA is stored in the tank 702, the pump 706 is activated and the heater 790 attached to the tank 702 is activated. Thereby, the IPA in the tank 702 is heated to an appropriate temperature below the boiling point (for example, about 70° C.), and the heated IPA is circulated in the circulation line 704 . In addition, the thermostat 708 also heats the IPA flowing in the circulation line 704 to maintain the IPA at an appropriate temperature. By heating the IPA, the solubility of the gas in the IPA is reduced, making it difficult for the gas to dissolve into the IPA in the tank, and part of the gas that has been dissolved into the IPA is detached from the IPA.

A part of the IPA flowing in the circulation line 704 flows into the degassing line 742, is degassed according to the aforementioned mechanism through the online megasonic device 744 and the hollow fiber membrane filter 750, and is returned to the tank 702. At this time, the IPA is also heated, so the degassing efficiency is improved.

The IPA flowing in the circulation line 704 flows into at least some branch supply lines 716 among the plurality of branch supply lines 716 (for example, the branch supply lines corresponding to the single-chip liquid processing unit 61 whose expected start time of the process is close), and does not go there. The nozzle 612 flows into the corresponding branch return line 730, and further returns to the tank 702 via the return line 734.

When the above state continues for a period of time and at least the following conditions are satisfied, the control device 100 determines that the single-chip liquid processing unit 61 is in a state in which IPA can be supplied to the substrate W (IPA available state).

- The gas concentration (eg oxygen concentration and/or carbon dioxide gas concentration) in the IPA is below a predetermined threshold via the dissolved gas monitor 746 of the degassing line 742.

- The gas concentration (eg oxygen concentration and/or carbon dioxide gas concentration) in the IPA is lower than a predetermined threshold through the dissolved gas monitor 718 corresponding to the single-chip liquid processing unit 61 close to the expected start time of processing.

As another condition, the temperature of the IPA circulating in the circulation line 704 is within a predetermined temperature range. In order to confirm the temperature of the IPA, a temperature sensor can be placed in the tank 702 or in an appropriate line connected to the tank.

It is preferable to start processing one substrate W in the single-wafer liquid processing unit 61 after confirming that the IPA supply state has been reached. When IPA is supplied to the substrate W, the cooler 726 is operated to close the on-off valve 732 and open the on-off valve 722 . As a result, the IPA whose temperature has been lowered to a predetermined temperature (for example, normal temperature to about 30° C.) by the cooler 726 is supplied to the substrate W from the IPA ejection nozzle 612 .

Next, the operation of the IPA supply mechanism 700 in the second structural example will be described. Similar to the first structural example, after IPA is supplied from the IPA supply source 760 to the tank 702 and a predetermined amount of IPA is stored in the tank 702, the inside of the tank 702 is depressurized by the vacuum pump 770 to satisfy the "tank 702 The internal pressure (not gauge pressure, but absolute pressure) is greater than the vapor pressure of IPA." And, pump 706 works. Since the pressure inside the tank 702 has been reduced, part of the gas dissolved in the IPA escapes from the IPA. Like the first structural example, IPA circulates in the circulation line 704, and part of the IPA flowing in the circulation line 704 flows into the degassing line 742, and is filtered by the online megasonic device 744 and the hollow fiber membrane provided in the degassing line 742. Device 750 is used for degassing.

In addition, similarly to the first structural example, the IPA flowing in the circulation line 704 flows into at least some branch supply lines 716 among the plurality of branch supply lines 716 (for example, the single-chip liquid processing unit 61 whose expected start time of treatment is close to The corresponding branch supply line) does not go to the nozzle 612, but flows into the corresponding branch return line 730, and further returns to the tank 702 via the return line 734. At this time, as in the first structural example, the dissolved gas concentration is monitored using the dissolved gas monitor 746 of the degassing line 742 and the dissolved gas monitor 718 of the branch supply line 716. After confirming that the IPA supply state has become After that, processing of one substrate W is allowed to start in the single-wafer liquid processing unit 61 . In the second structural example, unlike the first structural example, heating of the IPA in the tank 702 and cooling of the IPA in the branch supply line 716 are not performed.

Next, the flow of processing the substrate W in the substrate processing system 1 will be described. The first substrate transfer robot 23 in the loading and unloading unit 2 takes out the substrate W from the substrate transfer container C placed in the container placement unit 21 and places the taken out substrate W on the transfer unit 24 . Next, the second substrate transfer robot 63 of the processing unit 6 takes out the substrate W from the transfer unit 24 and carries it into the single-wafer liquid processing unit 61 .

The substrate W carried into the single-chip liquid processing unit 61 is held in a horizontal posture by the rotating holding disk 611 . Next, the substrate W is rotated around the vertical axis by rotating the holding disk 611 . In this state, the substrate W is subjected to liquid processing by sequentially supplying various processing liquids to the substrate W from one or more nozzles 612 that distribute various processing liquids required for the processing. An example of liquid treatment will be described below. First, a prewetting process is performed by supplying a prewetting liquid to the substrate W. Next, a chemical liquid treatment process (wet etching or chemical liquid cleaning) is performed by supplying a chemical liquid to the substrate W. Next, a rinse liquid (for example, DIW (pure water)) is supplied to the substrate W to perform rinsing processing. The chemical solution treatment process and flushing treatment can be performed multiple times each time.

In one embodiment, for example, the following process is performed on one substrate W.

Process 1: Pre-wet process using DIW

Process 2: DHF etching process

Process 3: DIW flushing process

Process 4: SC1 cleaning process

Process 5: DIW flushing process

In the above steps 1 to 5, DHF (dilute hydrofluoric acid) and SC1 are supplied from mutually different nozzles 612 . DIW may be supplied from the nozzle 612 dedicated to supplying DIW, or DIW may be supplied from the nozzle 612 for supplying DHF.

In the above-mentioned step 2, SiO ₂ (silicon oxide) is removed by DHF etching, and columnar bodies made of Si (silicon) and extending in the vertical direction are formed at approximately equal intervals. The same columnar body is also shown in FIG. 5 . In an exemplary embodiment, the substrate W is dried by a supercritical drying process described below while preventing damage to the columnar body made of Si.

After the last rinsing process (for example, the above-mentioned process 5), while continuing to rotate the substrate W, IPA is supplied to the substrate W from the IPA ejection nozzle 612, so that the surface of the substrate W (including the recessed portion of the pattern) is Surface) rinse liquid is replaced with IPA (IPA replacement step). Thereafter, while still supplying IPA from the nozzle, the rotation speed of the substrate is reduced to a very low speed to adjust the film thickness of IPA. Then, the supply of IPA is stopped, and the rotation of the substrate W is stopped. As a result, the surface of the substrate W is covered with an IPA liquid film (IPA slurry (Japanese: パドル)) of a desired film thickness (IPA slurry forming step). In this single-chip liquid processing unit 61, as the IPA supplied to the substrate W in the above-described IPA replacement step and the IPA slurry forming step, IPA that has been subjected to the above-mentioned degassing process is used.

It is preferable to set the atmosphere in the chamber of the single-chip liquid treatment unit 61 to an inert gas atmosphere, such as a nitrogen gas atmosphere, to prevent oxygen and carbon dioxide in the air from redissolving into the degassed IPA. Therefore, nitrogen gas is supplied from the fan filter unit 618 having a nitrogen gas ejection function. Nitrogen has lower solubility in IPA than oxygen and carbon dioxide gas. Therefore, by setting the atmosphere around the substrate W to which IPA is attached to a nitrogen atmosphere, the gas can be suppressed from dissolving into IPA.

It is preferable that the atmosphere in the chamber of the single-chip liquid processing unit 61 is a nitrogen atmosphere at least while the substrate W with IPA on its surface is in the chamber. Therefore, for example, it is preferable to make the atmosphere in the chamber a nitrogen atmosphere at the latest when the discharge of IPA is started. When the substrate W does not exist in the chamber and when the IPA is not attached to the surface of the substrate in the chamber, the chamber may be a clean air atmosphere with normal atmospheric components.

After the processing in the single-wafer liquid processing unit 61 is completed, the end effector (substrate holder) of the second substrate transfer robot 63 enters the single-wafer liquid processing unit 61 and rotates the substrate W with the IPA slurry formed on the surface. The holding tray 611 is taken out and transported to the supercritical drying unit 62 . The inside of the transfer space 64 through which the substrate W passes during transfer from the single-chip liquid processing unit 61 to the supercritical drying unit 62 has been adjusted to an inert gas (herein, nitrogen) atmosphere. Therefore, even when the substrate W passes through the transport space 64, it is possible to prevent oxygen and carbon dioxide in the air from re-dissolving into the IPA on the substrate W.

The second substrate transfer robot 63 places the substrate W carried into the supercritical drying unit 62 on the substrate support tray 622 of the supercritical drying unit 62 . Next, the substrate support tray 622 is accommodated in the supercritical chamber 621 , and the supercritical chamber 621 is sealed by the cover 625 integrated with the substrate support tray 622 . The inside of the casing of the supercritical drying unit 62 (inside the area 628) is also in an inert gas (herein, nitrogen) atmosphere. Therefore, it is possible to prevent oxygen and carbon dioxide in the air from redissolving into the substrate W until the substrate W is loaded into the supercritical drying unit 62 and stored in the supercritical chamber 621 while being placed on the substrate support tray 622 . on the IPA.

When the substrate W is accommodated in the supercritical chamber 621, a supercritical drying process is performed. First, a processing fluid (for example, CO ₂ ) is supplied into the supercritical chamber 621 through the supply port 623 from a supercritical fluid supply source (not shown), thereby increasing the pressure in the supercritical chamber 621 while supplying the pressure into the supercritical chamber 621 . Chamber 621 is filled with CO ₂ (pressurization step). In addition, before the pressure in the supercritical chamber 621 is increased, CO ₂ may be supplied through another supply port (not shown) opened toward the lower surface of the substrate support tray 622 .

After the pressure in the supercritical chamber 621 reaches the supercritical state guarantee pressure (the pressure that ensures that the CO ₂ single fluid and the mixed fluid of CO ₂ and IPA maintain the supercritical state), the circulation process is performed. In the flow process, CO ₂ supplied from the supply port 623 flows along the surface of the substrate W above the IPA slurry, and is discharged from the exhaust port 624 (see the arrow in the figure). By continuing this state, IPA on the surface of the substrate W is replaced with CO ₂ . After the IPA is replaced by supercritical CO ₂ , the exhaust port 624 side is connected to the normal pressure space to restore the normal pressure in the supercritical chamber 621 . Thereby, the supercritical CO ₂ on the surface of the substrate W is vaporized, and the surface of the substrate W is dried (discharging step). By doing so, the substrate W can be dried while preventing damage to the pattern formed on the surface of the substrate W.

Immediately after the substrate support tray 622 on which the substrate W is placed enters the supercritical chamber 621 (maintained at a relatively high temperature (for example, about 80° C.)), the temperature of the IPA on the substrate W rises, and with this, the temperature in the IPA rises. The dissolved gas vaporizes, creating bubbles in the IPA. When a fine and high aspect ratio pattern is formed on the surface of the substrate W, especially when thin and tall columnar portions extending in the vertical direction are arranged at intervals and grooves are formed between the columnar portions, when When large bubbles are generated in the IPA in the tank (for example, see mark B in FIG. 5 ), there is a risk that the columnar portion will be broken by the force generated by the expansion of the bubbles, thereby causing damage to the pattern. In this embodiment, since degassed IPA is used, bubbles are less likely to be generated, and thus pattern damage based on the above mechanism is less likely to occur.

In addition, since the space where the substrate W on which the IPA slurry is formed can exist is made into a nitrogen atmosphere, it is also possible to suppress an increase in the amount of dissolved gas of IPA during transportation. Therefore, pattern damage based on the above mechanism is less likely to occur.

Here, the above-mentioned "nitrogen atmosphere" does not need to be an atmosphere with a nitrogen concentration of 100%, and the nitrogen concentration in this atmosphere may be an appropriate value higher than the nitrogen concentration in air.

After the supercritical drying process is completed, the dried substrate W is taken out from the supercritical drying unit 62 by the second substrate transfer robot 63 and transferred to the transfer unit 24 . Next, the first substrate transfer robot 23 takes out the substrate W from the transfer unit 24 and stores it in the original substrate transfer container C located on the container placement unit 21 .

According to the above-mentioned embodiment, by using degassed IPA as the processing liquid that is replaced with the processing fluid in the supercritical state when performing the supercritical drying process, damage to the pattern can be prevented or significantly suppressed. In addition, by setting the atmosphere of the space for conveying the substrate with the IPA slurry to a nitrogen atmosphere, damage to the pattern can be more reliably prevented or significantly suppressed.

It should be understood that the embodiments disclosed this time are illustrative in every respect and are not restrictive. The above-described embodiments can be omitted, replaced, or modified in various ways without departing from the appended claims and the gist thereof.

The substrate is not limited to a semiconductor wafer, and may be other types of substrates used in the manufacture of semiconductor devices, such as glass substrates and ceramic substrates. In addition, in the above embodiment, the atmosphere in the tank (702) during degassing and the atmosphere in the space where the substrate W on which the IPA slurry is formed is present or transported is a nitrogen atmosphere. However, it is not limited to this and may be a nitrogen atmosphere. Other inert gas (such as argon) atmosphere.

Claims (13)

1. A substrate processing method, comprising:

a degassing step of removing dissolved gas in the treatment liquid;

a liquid film forming step of supplying the processing liquid from which the dissolved gas has been removed to a surface of a substrate to form a liquid film of the processing liquid covering the surface of the substrate;

a carry-in step of carrying the substrate on which the liquid film is formed into a processing container; and

and a supercritical drying step of maintaining a pressure in the processing container in which the substrate having the liquid film formed thereon is carried to a pressure at which a processing fluid is maintained in a supercritical state, and flowing the processing fluid into the processing container, thereby replacing the processing fluid covering the surface of the substrate with the processing fluid, and thereafter drying the surface of the substrate by vaporizing the processing fluid.

2. The method for processing a substrate according to claim 1, wherein,

the degassing step includes heating the treatment liquid to a temperature below the boiling point.

3. The method for processing a substrate according to claim 2, wherein,

the degassing step includes: the inside of a container storing the treatment liquid is set to an inert gas atmosphere, and the treatment liquid stored in the container is heated to a temperature lower than the boiling point of the treatment liquid.

4. The method for processing a substrate according to claim 3, wherein,

the inactive gas is nitrogen or argon.

5. The method for processing a substrate according to claim 1, wherein,

the degassing step includes: the container storing the treatment liquid is depressurized and exhausted.

6. The method for processing a substrate according to claim 1, wherein,

the degassing step includes: applying ultrasonic vibration to the treatment liquid to generate bubbles in the treatment liquid; and removing the bubbles from the treatment liquid.

7. The method for processing a substrate according to claim 6, wherein,

the following process is performed by using an online degassing mechanism provided in a circulation path connected to a container for storing the process liquid while the process liquid is caused to flow in the circulation path: generating the bubbles in the treatment liquid; and removing the bubbles from the treatment liquid.

8. The substrate processing method according to claim 1, further comprising:

the atmosphere of the space through which the substrate on which the liquid film of the processing liquid is formed passes is set to an inert gas atmosphere during a period from the end of the liquid film forming process to the end of the carry-in process.

9. The method for processing a substrate according to claim 8, wherein,

the inactive gas is nitrogen or argon.

10. The substrate processing method according to claim 1, further comprising:

and a chemical treatment step of performing chemical treatment on the substrate before the liquid film forming step.

11. The method for processing a substrate according to claim 10, wherein,

the liquid medicine treatment is etching treatment.

12. The method for processing a substrate according to claim 11, wherein,

a pattern having a plurality of grooves is formed on the substrate by the etching process.

13. A substrate processing system is provided with:

a liquid treatment unit that performs a liquid film forming process on a substrate;

a treatment liquid supply mechanism that supplies a treatment liquid used in the liquid treatment unit, and that includes a degasifier that removes dissolved gas from the treatment liquid;

a supercritical drying unit that performs supercritical drying treatment on the substrate;

a transport device that transports the substrate from the liquid processing unit to the supercritical drying unit; and

a control section that controls an operation of the substrate processing system to execute the substrate processing method according to any one of claims 1 to 7.