JP7458533B2 - Processing fluid supply device - Google Patents

Description

TECHNICAL FIELD The disclosed embodiments relate to processing fluid supply devices.

Conventionally, a liquid film for drying prevention is formed on the surface of a substrate such as a semiconductor wafer (hereinafter referred to as a wafer), and the wafer on which such a liquid film is formed is brought into contact with a processing fluid in a supercritical state to dry it. A substrate processing apparatus that performs processing is known (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2013-251547

The present disclosure provides a technique that can supply the processing fluid to a substrate processing apparatus at once when pumping the processing fluid in a liquid state.

A processing fluid supply device according to one aspect of the present disclosure includes a circulation line, a gas supply line, a cooling section, a pump, a branch line, a heating section, a pressure regulating section, a valve, a back pressure valve, and a control section. and. The circulation line circulates processing fluid that processes the substrate. The gas supply line supplies the processing fluid in a gaseous state to the circulation line. The cooling section is provided in the circulation line and cools the processing fluid in a gaseous state to generate the processing fluid in a liquid state. A pump is provided downstream of the cooling section in the circulation line. The branch line is connected downstream of the pump in the circulation line, and branches the processing fluid in a liquid state from the branch part. The heating section is provided downstream of the branch section, and heats the processing fluid in a liquid state to generate the processing fluid in a supercritical state. The pressure regulating section is provided in the circulation line downstream of the heating section and upstream of the connection section between the circulation line and the gas supply line, and reduces the pressure of the processing fluid in a supercritical state to a gas state. of the processing fluid. A valve is provided downstream of the pressure regulating section in the circulation line, and switches on and off the flow of the processing fluid in the circulation line. A back pressure valve is provided in the branch line between the branch part and the valve. The control section controls each section. Further, the control unit performs a process of branching the processing fluid in a liquid state from the circulation line to a branch line by fully closing the opening degree of the back pressure valve.

According to the present disclosure, when pumping out the processing fluid in a liquid state, the processing fluid can be supplied to the substrate processing apparatus at once.

FIG. 1 is a diagram illustrating a configuration example of a substrate processing apparatus according to an embodiment. FIG. 2 is a diagram illustrating a configuration example of a liquid processing unit according to an embodiment. FIG. 3 is a schematic perspective view showing a configuration example of the drying unit according to the embodiment. FIG. 4 is a diagram showing an example of the overall system configuration of the substrate processing system according to the embodiment. FIG. 5 is a diagram showing changes in the circulation pressure of the circulation line and the internal pressure of the drying unit according to the embodiment. FIG. 6 is a diagram for explaining standby processing of the substrate processing system according to the embodiment. FIG. 7 is a diagram for explaining the pressure increasing process and the holding process of the substrate processing system according to the embodiment. FIG. 8 is a diagram for explaining distribution processing of the substrate processing system according to the embodiment. FIG. 9 is a diagram for explaining the depressurization process of the substrate processing system according to the embodiment. FIG. 10 is a diagram for explaining the pressure increasing process and the holding process of the substrate processing system according to a modification of the embodiment. FIG. 11 is a diagram for explaining distribution processing of a substrate processing system according to a modification of the embodiment. FIG. 12 is a flowchart illustrating the procedure of processing fluid supply processing according to the embodiment.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a substrate processing system and a processing fluid supply method disclosed in the present application will be described in detail with reference to the accompanying drawings. Note that the present disclosure is not limited to the embodiments described below. Furthermore, it should be noted that the drawings are schematic, and the dimensional relationship of each element, the ratio of each element, etc. may differ from reality. Furthermore, drawings may include portions with different dimensional relationships and ratios.

Conventionally, a liquid film for drying prevention is formed on the surface of a substrate such as a semiconductor wafer (hereinafter referred to as a wafer), and the wafer on which the liquid film is formed is brought into contact with a processing fluid in a supercritical state to dry it. Substrate processing apparatuses that perform processing are known.

In a processing fluid supply device that supplies processing fluid to such a substrate processing device, the piping from the processing fluid supply source to the substrate processing device is formed in series, so even if an attempt is made to filter out foreign substances in the processing fluid, the filtration will not be possible. There is a limit to the number of times you can do it.

Therefore, by forming a circulation line for circulating the processing fluid in the processing fluid supply device and providing a filter in the circulation line, it is possible to increase the number of times of filtration and improve the performance of removing foreign substances.

However, when an incompressible liquid processing fluid is pumped and circulated in such a circulation line, there is a problem in that the influence of pulsation generated by such a pump is large. For example, such pulsation may cause damage to the pump or piping, or may shorten the life of the pump or piping by placing a load on welded or threaded joints.

Therefore, it is expected to reduce the influence of pulsation caused by such a pump when pumping a processing fluid in a liquid state.

<Configuration of the Substrate Processing Apparatus>
First, the configuration of a substrate processing apparatus 1 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of the configuration of a substrate processing apparatus 1 according to an embodiment. In the following, to clarify the positional relationship, an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other are defined, and the positive direction of the Z-axis is defined as the vertical upward direction.

As shown in FIG. 1, the substrate processing apparatus 1 includes a loading/unloading station 2 and a processing station 3. The loading/unloading station 2 and the processing station 3 are provided adjacent to each other.

The loading/unloading station 2 includes a carrier placement section 11 and a transport section 12. A plurality of carriers C, each of which holds a plurality of semiconductor wafers W (hereinafter referred to as "wafers W") in a horizontal position, are placed on the carrier placement section 11.

The transport section 12 is provided adjacent to the carrier placement section 11. Inside the transport section 12, a transport device 13 and a transfer section 14 are arranged.

The transport device 13 includes a wafer holding mechanism that holds the wafer W. Further, the transport device 13 is capable of horizontal and vertical movement and rotation about a vertical axis, and transports the wafer W between the carrier C and the transfer section 14 using a wafer holding mechanism. .

The processing station 3 is provided adjacent to the transport section 12 . The processing station 3 includes a transport block 4 and a plurality of processing blocks 5.

The transport block 4 includes a transport area 15 and a transport device 16. The transport area 15 is, for example, a rectangular parallelepiped-shaped area that extends along the direction in which the loading/unloading stations 2 and the processing stations 3 are lined up (X-axis direction). A transport device 16 is arranged in the transport area 15 .

The transport device 16 includes a wafer holding mechanism that holds the wafer W. Further, the transfer device 16 is capable of horizontal and vertical movement and rotation about a vertical axis, and is capable of transferring wafers W between the transfer unit 14 and the plurality of processing blocks 5 using a wafer holding mechanism. Perform transportation.

The plurality of processing blocks 5 are arranged adjacent to the transport area 15 on both sides of the transport area 15 . Specifically, the plurality of processing blocks 5 are located on one side (Y-axis positive direction side) of the conveyance area 15 in the direction (Y-axis direction) perpendicular to the direction in which the loading/unloading stations 2 and the processing stations 3 are lined up (X-axis direction). ) and the other side (Y-axis negative direction side).

Further, although not illustrated, the plurality of processing blocks 5 are arranged in multiple stages (for example, three stages) along the vertical direction. The transfer of the wafer W between the processing block 5 arranged at each stage and the transfer section 14 is performed by one transfer device 16 arranged in the transfer block 4. Note that the number of stages of the plurality of processing blocks 5 is not limited to three stages.

Each processing block 5 includes a liquid processing unit 17, a drying unit 18, and a supply unit 19. The drying unit 18 is an example of a substrate processing section.

The liquid processing unit 17 performs a cleaning process to clean the upper surface of the wafer W, which is the pattern formation surface. Further, the liquid processing unit 17 performs a liquid film forming process to form a liquid film on the upper surface of the wafer W after the cleaning process. The configuration of the liquid processing unit 17 will be described later.

The drying unit 18 performs a supercritical drying process on the wafer W after the liquid film forming process. Specifically, the drying unit 18 dries the wafer W after the liquid film formation process by bringing the wafer W into contact with a processing fluid in a supercritical state (hereinafter also referred to as "supercritical fluid"). The configuration of the drying unit 18 will be described later.

The supply unit 19 supplies the processing fluid to the drying unit 18. Specifically, the supply unit 19 includes a group of supply devices including a flow meter, a flow regulator, a back pressure valve, a heater, etc., and a housing that houses the group of supply devices. In this embodiment, the supply unit 19 supplies _CO2 as the processing fluid to the drying unit 18. The configuration of the supply unit 19 will be described later.

Further, a processing fluid supply device 60 (see FIG. 4) that supplies processing fluid is connected to the supply unit 19. In an embodiment, the processing fluid supply device 60 supplies CO ₂ to the supply unit 19 as the processing fluid. Details of the processing fluid supply device 60 will be described later.

The liquid processing unit 17, drying unit 18 and supply unit 19 are arranged along the transport area 15 (i.e., along the X-axis direction). Of the liquid processing unit 17, drying unit 18 and supply unit 19, the liquid processing unit 17 is disposed at a position closest to the loading/unloading station 2, and the supply unit 19 is disposed at a position farthest from the loading/unloading station 2.

In this way, each processing block 5 has one liquid processing unit 17, one drying unit 18, and one supply unit 19. In other words, the substrate processing apparatus 1 is provided with the same number of liquid processing units 17, transport devices 16, and supply units 19.

The drying unit 18 also includes a processing area 181 where supercritical drying processing is performed, and a transfer area 182 where wafers W are transferred between the transport block 4 and the processing area 181. The processing area 181 and the delivery area 182 are arranged along the conveyance area 15.

Specifically, of the processing area 181 and the delivery area 182, the delivery area 182 is arranged closer to the liquid processing unit 17 than the processing area 181 is. That is, in each processing block 5, the liquid processing unit 17, the delivery area 182, the processing area 181, and the supply unit 19 are arranged in this order along the transport area 15.

As shown in FIG. 1, the substrate processing apparatus 1 includes a control device 6. As shown in FIG. The control device 6 is, for example, a computer, and includes a control section 7 and a storage section 8.

The control unit 7 includes a microcomputer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), input/output ports, and various circuits. The CPU of the microcomputer reads and executes programs stored in the ROM to realize control of the conveying devices 13, 16, the liquid processing unit 17, the drying unit 18, the supply unit 19, and the like.

The program may be stored in a computer-readable storage medium and installed from that storage medium into the storage unit 8 of the control device 6. Examples of computer-readable storage media include a hard disk (HD), a flexible disk (FD), a compact disk (CD), a magnetic optical disk (MO), and a memory card.

The storage unit 8 is realized by, for example, a semiconductor memory element such as a RAM or a flash memory, or a storage device such as a hard disk or an optical disk.

In the substrate processing apparatus 1 configured as described above, first, the transfer device 13 of the loading/unloading station 2 removes the wafer W from the carrier C placed on the carrier placement section 11, and places the removed wafer W on the transfer section 14. The wafer W placed on the transfer section 14 is removed from the transfer section 14 by the transfer device 16 of the processing station 3, and is transferred to the liquid processing unit 17.

The wafer W carried into the liquid processing unit 17 is subjected to a cleaning process and a liquid film forming process by the liquid processing unit 17, and then is carried out from the liquid processing unit 17 by the transport device 16. The wafer W carried out from the liquid processing unit 17 is carried into the drying unit 18 by the transport device 16, and is subjected to a drying process by the drying unit 18.

The wafer W that has been dried by the drying unit 18 is removed from the drying unit 18 by the transport device 16 and placed in the transfer section 14. The processed wafer W placed in the transfer section 14 is then returned to the carrier C in the carrier placement section 11 by the transport device 13.

<Configuration of liquid processing unit>
Next, the configuration of the liquid processing unit 17 will be explained with reference to FIG. 2. FIG. 2 is a diagram showing an example of the configuration of the liquid processing unit 17. The liquid processing unit 17 is configured as a single-wafer type cleaning device that cleans the wafers W one by one by spin cleaning, for example.

As shown in FIG. 2, the liquid processing unit 17 holds the wafer W substantially horizontally with a wafer holding mechanism 25 disposed in an outer chamber 23 forming a processing space, and rotates the wafer W around a vertical axis. The wafer W is rotated by rotating it.

Then, the liquid processing unit 17 moves the nozzle arm 26 above the rotating wafer W, and supplies the chemical liquid and rinsing liquid in a predetermined order from the chemical liquid nozzle 26a provided at the tip of the nozzle arm 26. , performs a cleaning process on the upper surface of the wafer W.

In addition, in the liquid processing unit 17, a chemical liquid supply path 25a is also formed inside the wafer holding mechanism 25. The underside of the wafer W is also cleaned by the chemical liquid and rinsing liquid supplied from the chemical liquid supply path 25a.

For example, the cleaning process first removes particles and organic contaminants using an alkaline chemical solution called SC1 liquid (a mixture of ammonia and hydrogen peroxide). Next, a rinse is performed using deionized water (DIW), which is a rinse solution.

Next, the native oxide film is removed using an acidic chemical solution called diluted hydrofluoric acid (hereinafter referred to as "DHF"), and then rinsing is performed using DIW.

The various chemical solutions described above are received by the outer chamber 23 and the inner cup 24 disposed in the outer chamber 23, and are received by a drain port 23a provided at the bottom of the outer chamber 23 and a drain provided at the bottom of the inner cup 24. The liquid is discharged from the liquid port 24a. Furthermore, the atmosphere within the outer chamber 23 is exhausted from an exhaust port 23b provided at the bottom of the outer chamber 23.

The liquid film formation process is performed after the rinsing process in the cleaning process. Specifically, the liquid processing unit 17 supplies liquid IPA (Isopropyl Alcohol) (hereinafter also referred to as "IPA liquid") to the upper and lower surfaces of the wafer W while rotating the wafer holding mechanism 25. This replaces the DIW remaining on both sides of the wafer W with IPA. The liquid processing unit 17 then gently stops the rotation of the wafer holding mechanism 25.

After the liquid film formation process, the wafer W, with the IPA liquid film formed on its upper surface, is transferred to the transfer device 16 by a transfer mechanism (not shown) provided in the wafer holding mechanism 25, and is removed from the liquid processing unit 17.

The liquid film formed on the wafer W is caused by evaporation (vaporization) of the liquid on the upper surface of the wafer W during the transfer of the wafer W from the liquid processing unit 17 to the drying unit 18 or during the operation of carrying the wafer W into the drying unit 18. This prevents pattern collapse from occurring.

<Configuration of Drying Unit>
Next, the configuration of the drying unit 18 will be described with reference to Fig. 3. Fig. 3 is a schematic perspective view showing an example of the configuration of the drying unit 18.

The drying unit 18 includes a main body 31, a holding plate 32, and a lid member 33. An opening 34 for loading and unloading the wafer W is formed in the housing-like main body 31. The holding plate 32 holds the wafer W to be processed in the horizontal direction. The lid member 33 supports the holding plate 32 and seals the opening 34 when the wafer W is carried into the main body 31.

The main body 31 is a container in which a processing space capable of accommodating a wafer W having a diameter of 300 mm, for example, is formed therein, and supply ports 35 and 36 and a discharge port 37 are provided on the wall thereof. The supply ports 35 and 36 and the discharge port 37 are connected to a supply channel and a discharge channel for flowing supercritical fluid to the drying unit 18, respectively.

The supply port 35 is connected to the side surface of the housing-like main body 31 opposite to the opening 34 . Further, the supply port 36 is connected to the bottom surface of the main body 31. Furthermore, the discharge port 37 is connected to the lower side of the opening 34 . Although two supply ports 35, 36 and one discharge port 37 are illustrated in FIG. 3, the number of supply ports 35, 36 and discharge port 37 is not particularly limited.

Further, inside the main body 31, fluid supply headers 38 and 39 and a fluid discharge header 40 are provided. The fluid supply headers 38 and 39 have a plurality of supply ports arranged in line in the longitudinal direction of the fluid supply headers 38 and 39, and the fluid discharge header 40 has a plurality of discharge ports arranged in the longitudinal direction of the fluid discharge header 40. are formed in parallel.

The fluid supply header 38 is connected to the supply port 35 and is provided inside the casing-like main body 31 adjacent to the side opposite to the opening 34 . Further, the plurality of supply ports formed in line with the fluid supply header 38 face the opening 34 side.

The fluid supply header 39 is connected to the supply port 36 and is provided at the center of the bottom inside the casing-like main body 31 . Further, the plurality of supply ports formed in line with the fluid supply header 39 face upward.

The fluid discharge header 40 is connected to the discharge port 37 and is provided inside the casing-like main body 31 adjacent to the side surface on the opening 34 side and below the opening 34 . Moreover, the plurality of discharge ports formed in parallel with the fluid discharge header 40 face upward.

The fluid supply headers 38 and 39 supply the supercritical fluid into the main body 31. The fluid discharge header 40 guides the supercritical fluid in the main body 31 to the outside of the main body 31 and discharges it. The supercritical fluid discharged to the outside of the main body 31 via the fluid discharge header 40 includes IPA liquid that has been dissolved in the supercritical fluid in a supercritical state from the surface of the wafer W.

In the drying unit 18, the IPA liquid between the patterns formed on the wafer W comes into contact with the supercritical fluid under high pressure (for example, 16 MPa) and gradually dissolves into the supercritical fluid. During the pattern, it is gradually replaced by supercritical fluid. Finally, the spaces between the patterns are filled only with supercritical fluid.

Then, after the IPA liquid is removed from between the patterns, the pressure inside the main body 31 is reduced from a high pressure state to atmospheric pressure, so that CO ₂ changes from a supercritical state to a gas state, and only gas is present between the patterns. occupied by In this way, the IPA liquid between the patterns is removed, and the drying process of the wafer W is completed.

Here, supercritical fluids have lower viscosity and higher ability to dissolve liquids than liquids (for example, IPA liquids), and in addition, supercritical fluids have an interface between the supercritical fluid and liquids or gases that are in equilibrium. not exist. Thereby, in the drying process using the supercritical fluid, the liquid can be dried without being affected by surface tension. Therefore, according to the embodiment, it is possible to suppress the pattern from collapsing during the drying process.

In the embodiment, an example is shown in which IPA liquid is used as the liquid for preventing drying, and _CO2 in a supercritical state is used as the processing fluid, but a liquid other than IPA may be used as the liquid for preventing drying, and a fluid other than _CO2 in a supercritical state may be used as the processing fluid.

<Substrate processing system configuration>
Next, the configuration of the substrate processing system 100 according to the embodiment will be described with reference to FIG. 4. FIG. 4 is a diagram showing an example of the overall system configuration of the substrate processing system 100 according to the embodiment. Note that each part of the substrate processing system 100 described below can be controlled by the control unit 7.

The substrate processing system 100 includes a processing fluid supply source 90, a processing fluid supply device 60, and a substrate processing apparatus 1. The processing fluid supply device 60 supplies the processing fluid supplied from the processing fluid supply source 90 to the substrate processing apparatus 1 . As described above, the substrate processing apparatus 1 includes the drying unit 18 and the supply unit 19, and processes the wafer W within the drying unit 18 using the processing fluid supplied via the supply unit 19.

The processing fluid supply device 60 has a gas supply line 61 , a circulation line 62 , and a branch line 63 . The gas supply line 61 is connected to a processing fluid supply source 90 and supplies a gaseous processing fluid from the processing fluid supply source 90 to the circulation line 62 . Processing fluid supply source 90 is also connected to connection 66 via valve 64 and flow regulator 65 .

The circulation line 62 is a circulation line that exits from a connection portion 66 that is connected to the gas supply line 61 and returns to the connection portion 66 . The circulation line 62 includes a filter 67, a condenser 68, a tank 69, a pump 70, a pressure sensor 71, a branch part 72, a spiral heater 74, and a backbone in order from the upstream side with respect to the connection part 66. A pressure valve 75 and a valve 76 are provided.

The filter 67 filters the gaseous processing fluid flowing within the circulation line 62 to remove foreign substances contained in the processing fluid. By removing foreign matter from the processing fluid using the filter 67, it is possible to suppress generation of particles on the surface of the wafer W during the drying process of the wafer W using the supercritical fluid.

Condenser 68 is an example of a cooling section. The condenser 68 is connected to, for example, a cooling water supply section (not shown), and is capable of exchanging heat between the cooling water and the gaseous processing fluid. Thereby, the condenser 68 cools the gaseous processing fluid flowing within the circulation line 62 to generate liquid processing fluid.

The tank 69 stores the liquid processing fluid generated by the condenser 68 . The pump 70 sends out the liquid processing fluid stored in the tank 69 to the downstream side of the circulation line 62 . That is, pump 70 creates a circulating flow of process fluid out of tank 69 , through circulation line 62 , and back to tank 69 . The pressure sensor 71 measures the circulating pressure of the processing fluid flowing through the circulation line 62 .

One or more branch lines 63 branch off from a branch point 72 of the circulation line 62. In other words, one or more branch lines 63 are connected to the branch point 72. Such branch lines 63 are connected to a corresponding substrate processing apparatus 1 and supply the liquid-state processing fluid flowing through the circulation line 62 to the corresponding substrate processing apparatus 1.

Further, a valve 73 is provided in the branch line 63 within the processing fluid supply device 60 . The valve 73 is a valve that adjusts the flow of the processing fluid on and off, and when it is open, the processing fluid flows into the downstream branch line 63, and when it is closed, the processing fluid does not flow into the downstream branch line 63.

The spiral heater 74 is an example of a heating unit. The spiral heater 74 is wound around the circulation line 62 and heats the liquid processing fluid flowing through the circulation line 62 to generate a supercritical processing fluid.

The back pressure valve 75 is an example of a pressure regulating section. The back pressure valve 75 is configured to maintain the primary side pressure at the set pressure by adjusting the valve opening and causing fluid to flow to the secondary side when the primary side pressure of the circulation line 62 exceeds the set pressure. be done.

Then, the back pressure valve 75 reduces the pressure of the supercritical processing fluid flowing through the circulation line 62 to generate a gaseous processing fluid. Note that the valve opening degree and set pressure of the back pressure valve 75 can be changed by the control unit 7 at any time.

The valve 76 is a valve that adjusts the flow of processing fluid on and off, and when it is open, the processing fluid flows into the downstream circulation line 62, and when it is closed, the processing fluid does not flow into the downstream circulation line 62.

The gaseous processing fluid generated by the back pressure valve 75 then returns to the connection portion 66 of the circulation line 62 via the valve 76 .

Next, the system configuration within the substrate processing apparatus 1 will be explained. The processing fluid flowing through the branch line 63 is supplied to the drying unit 18 via the supply line 41 of the supply unit 19 and is discharged from the drying unit 18 to the outside via the discharge line 42. Note that the branch line 63 of the processing fluid supply device 60 and the supply line 41 of the substrate processing device 1 are connected by a connection line 80 disposed within a factory or the like.

The supply line 41 is provided with, in order from the upstream side, a valve 43, a heater 44, a temperature sensor 45, an orifice 46, a filter 47, and a valve 48.

Valve 43 is a valve that adjusts the flow of the treatment fluid on and off. When open, it allows the treatment fluid to flow into the downstream supply line 41, and when closed, it does not allow the treatment fluid to flow into the downstream supply line 41.

Heater 44 is an example of another heating section. The heater 44 heats the processing fluid in a liquid state flowing through the supply line 41 to generate a processing fluid in a supercritical state. The temperature sensor 45 detects the temperature of the supercritical processing fluid generated by the heater 44 .

The orifice 46 serves to reduce the flow rate of the supercritical processing fluid generated by the heater 44 and adjust the pressure. The orifice 46 can pass the supercritical processing fluid, the pressure of which is adjusted to, for example, about 16 MPa, through the downstream supply line 41.

The filter 47 filters the supercritical processing fluid flowing through the supply line 41 and removes foreign matter contained in the processing fluid. By removing foreign matter from the processing fluid using the filter 47, it is possible to suppress the generation of particles on the surface of the wafer W during the drying process of the wafer W using the supercritical fluid.

Valve 48 is a valve that adjusts the flow of the processing fluid on and off. When open, the processing fluid flows to the downstream drying unit 18, and when closed, the processing fluid does not flow to the downstream drying unit 18.

The drying unit 18 is provided with a temperature sensor 49. The temperature sensor 49 detects the temperature of the processing fluid filled in the drying unit 18.

The discharge line 42 is provided with a pressure sensor 50, a valve 51, a flow meter 52, and a back pressure valve 53 in this order from the upstream side. Pressure sensor 50 measures the pressure of the process fluid flowing through discharge line 42 . Note that since the pressure sensor 50 is directly connected to the drying unit 18 via the discharge line 42, the pressure of the processing fluid measured by the pressure sensor 50 is approximately equal to the internal pressure of the processing fluid in the drying unit 18. .

The valve 51 is a valve that adjusts the ON/OFF state of the flow of the processing fluid, and when in the open state, the processing fluid flows into the downstream discharge line 42, and when the valve 51 closes, the processing fluid does not flow into the downstream discharge line 42. Flow meter 52 measures the flow rate of processing fluid flowing through discharge line 42 .

The back pressure valve 53 is configured to maintain the primary side pressure at the set pressure by adjusting the valve opening and causing fluid to flow to the secondary side when the primary side pressure of the discharge line 42 exceeds the set pressure. be done. Note that the valve opening degree and set pressure of the back pressure valve 53 can be changed by the control unit 7 at any time.

<Substrate processing of embodiment>
Next, details of substrate processing in the substrate processing system 100 according to the embodiment will be described with reference to FIGS. 5 to 9. FIG. 5 is a diagram showing changes in the circulation pressure of the circulation line 62 and the internal pressure of the drying unit 18 according to the embodiment.

As shown in FIG. 5, in the substrate processing system 100, standby processing is performed until time T1. In this standby process, the internal pressure of the drying unit 18 is a predetermined pressure P0 (for example, atmospheric pressure), and the circulation pressure of the circulation line 62 is a predetermined pressure P4 (for example, 19 MPa).

Figure 6 is a diagram for explaining the standby process of the substrate processing system 100 according to the embodiment. As shown in Figure 6, during such standby process, the valve 64 is in an open state, and therefore the gaseous processing fluid is supplied from the processing fluid supply source 90 to the circulation line 62 via the valve 64, the flow regulator 65, and the connection part 66.

Further, since the processing fluid circulating in the circulation line 62 is also in a gaseous state downstream of the back pressure valve 75, the processing fluid in a gaseous state flowing in the gas supply line 61 and the circulation line 62 join together at the connection portion 66.

Then, the combined gaseous processing fluid is filtered by a filter 67 downstream of the connection part 66. Here, when the filter 67 filters the processing fluid in a gaseous state rather than in a liquid state or a supercritical state, the filter 67 can improve the performance of removing foreign substances contained in the processing fluid.

That is, in the embodiment, by providing the filter 67 at a portion of the circulation line 62 where the processing fluid in a gaseous state flows, foreign substances contained in the processing fluid can be effectively removed. Therefore, according to the embodiment, generation of particles on the surface of the wafer W can be effectively suppressed during the drying process of the wafer W using a supercritical fluid.

The gaseous processing fluid filtered by the filter 67 is cooled by the condenser 68 to become a liquid processing fluid, which is stored in a tank 69 . The processing fluid stored in the tank 69 is then sent to the downstream side of the circulation line 62 by a pump 70.

Then, the processing fluid in a liquid state that has passed through the branch section 72 is heated by the spiral heater 74, and becomes a processing fluid in a supercritical state. Further, the supercritical processing fluid is reduced in pressure by the back pressure valve 75 and becomes a gaseous processing fluid.

In addition, the valve opening of the back pressure valve 75 is controlled, for example, by PID (Proportional-Integral-Differential) control based on the pressure measured by the pressure sensor 71 so that the circulation pressure in the circulation line 62 is maintained at a predetermined pressure P4.

Then, the processing fluid that has become gaseous at the back pressure valve 75 flows to the connection portion 66 via the valve 76 in the open state. Note that when the substrate processing system 100 is performing standby processing, the processing fluid is not supplied to the substrate processing apparatus 1, so the valve 73 of the branch line 63 is in a closed state.

Here, in the embodiment, between the pump 70 and the back pressure valve 75, the spiral heater 74 changes the phase of the processing fluid from a liquid state to a supercritical state. That is, the space between the pump 70 and the valve 73 or back pressure valve 75 that can be in a closed state is not filled with an incompressible liquid state processing fluid, but a supercritical state processing fluid that is partially compressible. It has become a fluid.

Thereby, even when the incompressible liquid processing fluid is sent out and circulated by the pump 70 in the circulation line 62, the pulsations generated by the pump 70 can be absorbed in the supercritical state region. Therefore, according to the embodiment, when pump 70 pumps out the processing fluid in a liquid state, it is possible to reduce the influence of pulsation that occurs in pump 70 .

Returning to the explanation of FIG. 5. In the substrate processing system 100, a pressure increasing process is performed to increase the internal pressure of the drying unit 18 to a predetermined pressure P1 (for example, 16 MPa) from time T1 to time T4. Then, from time T4 to time T5, a holding process is performed in which the inside of the drying unit 18 is held at pressure P1.

FIG. 7 is a diagram for explaining the pressure increasing process and the holding process of the substrate processing system 100 according to the embodiment. Note that in the following description, descriptions of parts that are in the same state as the processes already described may be omitted.

As shown in FIG. 7, at time T1 when the pressure increasing process is started to fill the drying unit 18 with the processing fluid, the valve 73, the valve 43, and the valve 48 are opened, and the valve 51 is closed.

As a result, the processing fluid circulating through the circulation line 62 reaches the heater 44 in a liquid state, and undergoes a phase change in the heater 44 to a supercritical state. The drying unit 18 is then filled with the processing fluid that has become supercritical.

In this manner, in the embodiment, the processing fluid is supplied from the processing fluid supply device 60 to the substrate processing apparatus 1 in a liquid state rather than a gas state or a supercritical state. Thereby, even if variations occur in the distance between the processing fluid supply device 60 and the substrate processing apparatus 1, that is, the length of the connection line 80, problems caused by such variations in length can be reduced.

Furthermore, when the valves 73, 43, and 48 are opened, the back pressure valve 75 is fully closed, and the valve 76 is closed, temporarily stopping the circulation of the processing fluid in the circulation line 62. stop. Thereby, the processing fluid can be supplied to the substrate processing apparatus 1 at once.

As shown in FIG. 5, immediately after the pressure increase process begins, the circulation pressure in the circulation line 62 temporarily drops from pressure P4, but as the drying unit 18 fills with the processing fluid, the circulation pressure rises.

Then, at time T2, a predetermined time (e.g., 3 seconds) after time T1, the valve opening of the backpressure valve 75 is changed from the fully closed state to a predetermined fixed opening, and the valve 76 is opened, as shown in FIG. 7, to resume circulation of the treatment fluid in the circulation line 62.

Next, as shown in FIG. 5, at time T3 when the circulation pressure in the circulation line 62 further increases and reaches a predetermined pressure P3 (for example, 18 MPa), as shown in FIG. Switch the opening to PID control. Thereby, as shown in FIG. 5, after the circulation pressure in the circulation line 62 reaches pressure P4, the circulation pressure can be maintained at pressure P4.

In this way, instead of immediately switching the valve opening degree of the back pressure valve 75 from the fully closed state to the PID control, by inserting a predetermined fixed opening degree in between, the circulating pressure in the circulation line 62 is changed to the pressure P4 in the PID control. It is possible to suppress overshooting.

Then, at time T4, which is a while after the internal pressure of the drying unit 18 reaches the predetermined pressure P1, the valve 48 on the upstream side of the drying unit 18 is closed, as shown in FIG. is held at pressure P1.

In the holding process, the IPA concentration and _CO2 concentration of the mixed fluid of the processing fluid and IPA liquid mixed between the patterns formed on the wafer W are set to predetermined concentrations (for example, the IPA concentration is 30% or less, the _CO2 concentration is 70% % or more).

Following the holding process, the substrate processing system 100 performs a distribution process from time T5 to time T6. FIG. 8 is a diagram for explaining distribution processing of the substrate processing system 100 according to the embodiment.

As shown in FIG. 8, in order to circulate the processing fluid within the drying unit 18, at time T5 when the flow process starts, the valve 51 is opened and the valve opening of the back pressure valve 53 is PID controlled. As a result, the internal pressure of the drying unit 18 continues to be maintained at a predetermined pressure P1, as shown in FIG. 5.

Furthermore, since the processing fluid is always supplied to the substrate processing apparatus 1 during distribution processing, the circulation pressure in the circulation line 62 decreases from pressure P4 to pressure P2 (for example, 17 MPa). In the embodiment, since the discharge capacity of the pump 70 and the consumption amount of processing fluid in the distribution process are approximately equal, as shown in FIG. The valve 76 is closed to stop the circulation of the processing fluid in the circulation line 62.

Here, in the distribution processing of the embodiment, the temperature of the processing fluid in the drying unit 18 is preferably 90° C. or higher. If the temperature of the processing fluid in the drying unit 18 is lower than a predetermined temperature (for example, 83°C), the processing fluid will no longer be in a 100% supercritical state, so foreign substances dissolved in the processing fluid may It may precipitate within the drying unit 18.

Such precipitated foreign matter may generate a large amount of particles on the surface of the wafer W during the drying process of the wafer W using a supercritical fluid.

However, in the embodiment, the temperature of the processing fluid in the drying unit 18 is set to 90°C or higher, which can prevent particles from being generated on the surface of the wafer W during the drying process of the wafer W using a supercritical fluid. Preferably, the temperature of the processing fluid in the drying unit 18 is set to 95°C or higher.

Further, in the embodiment, in order to maintain the processing fluid in the drying unit 18 at a high temperature, the temperature of the processing fluid in a supercritical state generated by the heater 44 may be set higher than the temperature of the processing fluid in the drying unit 18. . For example, the temperature of the supercritical processing fluid generated by the heater 44 may be in the range of 110°C to 120°C.

Thereby, even if the temperature of the processing fluid decreases due to adiabatic expansion when passing through the orifice 46, the temperature of the processing fluid within the drying unit 18 can be maintained at 90° C. or higher.

In addition, in the embodiment, if the temperature of the processing fluid in the drying unit 18 is made too high (for example, if the temperature of the processing fluid is made higher than 100°C), the liquid film of the IPA liquid formed on the wafer W will dry out due to the high temperature of the processing fluid.

This may cause problems such as the pattern formed on the wafer W falling over, so it is not preferable to make the temperature of the processing fluid in the drying unit 18 too high.

Further, the temperature of the processing fluid in the drying unit 18 can be monitored by a temperature sensor 49, and the temperature of the supercritical processing fluid generated by the heater 44 can be monitored by a temperature sensor 45.

Following the distribution process, the substrate processing system 100 performs a depressurization process from time T6 to time T7. FIG. 9 is a diagram for explaining the depressurization process of the substrate processing system 100 according to the embodiment.

As shown in FIG. 9, at time T6 when the decompression process starts, in order to reduce the pressure inside the drying unit 18, the valves 43 and 48 in the supply line 41 are closed, and the valve opening of the back pressure valve 53 in the discharge line 42 is changed to a predetermined fixed opening. As a result, the internal pressure of the drying unit 18 is reduced from pressure P1 to pressure P0 (atmospheric pressure) as shown in FIG. 5.

Further, at time T6, as shown in FIG. Restart process fluid circulation at the Further, at time T7 when a predetermined time (for example, 3 seconds) has elapsed from time T6, the valve opening degree of the back pressure valve 75 is switched to PID control.

As a result, as shown in FIG. 5, after the circulation pressure in the circulation line 62 reaches pressure P4, the circulation pressure can be maintained at pressure P4. Then, when the depressurization process ends at time T8, the substrate processing system 100 returns to the standby process described above.

<Modification>
Next, a modified example of the embodiment will be described with reference to Fig. 10 and Fig. 11. Fig. 10 is a diagram for explaining the pressure increase process and pressure holding process of the substrate processing system 100 according to the modified example of the embodiment.

Note that this modification differs from the embodiment in that the discharge capacity of the pump 70 is improved compared to the embodiment. Therefore, unlike the embodiment, the circulation of the processing fluid in the circulation line 62 can be maintained without closing the back pressure valve 75 and the valve 76 even when the pressure increasing process is started.

That is, as shown in FIG. 10, when the pressure increasing process is started, the valve 76 continues to remain open. Further, the opening degree of the back pressure valve 75 is changed from PID control to a predetermined fixed opening degree 1 at time T1 (see FIG. 5) when the pressure increase process is started. Next, at time T2 (see FIG. 5) when a predetermined time (for example, 3 seconds) has elapsed from time T1, the valve opening degree of the back pressure valve 75 is changed from the predetermined fixed opening degree 1 to the predetermined fixed opening degree 2. .

Then, at time T3 (see FIG. 5) when the circulation pressure in the circulation line 62 further increases and reaches a predetermined pressure P3 (see FIG. 5) (for example, 18 MPa), the valve opening degree of the back pressure valve 75 is controlled by PID control. Switch to Thereby, similarly to the embodiment, after the circulation pressure in the circulation line 62 reaches pressure P4 (see FIG. 5), the circulation pressure can be maintained at pressure P4.

FIG. 11 is a diagram for explaining distribution processing of the substrate processing system 100 according to a modification of the embodiment. As described above, since the discharge capacity of the pump 70 is improved in the modified example, the circulation of the processing fluid in the circulation line 62 can be maintained even during distribution processing, as shown in FIG. 11. .

Here, if the flow rate of the processing fluid flowing through the substrate processing apparatus 1 is excessively high, a problem may occur in which the fast flow of the processing fluid causes the pattern on the wafer W to collapse. Therefore, in the modified example, the amount of processing fluid circulated through the circulation line 62 is increased, thereby reducing the amount of processing fluid supplied to the substrate processing apparatus 1, thereby suppressing the flow rate of the processing fluid flowing through the substrate processing apparatus 1.

Specifically, the flow rate of the processing fluid flowing through the discharge line 42 is measured with a flow meter 52 provided in the discharge line 42 of the substrate processing apparatus 1, and the back pressure valve is adjusted based on the flow rate of the processing fluid flowing through the discharge line 42. Adjust the valve opening degree of 75 as appropriate. Thereby, in the modified example, the amount of processing fluid supplied to the substrate processing apparatus 1 can be adjusted within a favorable range.

In order to adjust the opening degree of the back pressure valve 75, first confirm that the processing fluid is flowing at the desired flow rate using the flow meter 52, and then adjust the valve opening degree of the back pressure valve 75 at the time of confirmation. It may be fixed with Further, the valve opening degree of the back pressure valve 75 may be adjusted by feedback control of the valve opening degree of the back pressure valve 75 based on the flow rate of the processing fluid measured from time to time by the flow meter 52.

The substrate processing system 100 according to the embodiment includes a substrate processing apparatus 1 for processing a substrate (wafer W) with a processing fluid, and a processing fluid supplying apparatus 60 for supplying the processing fluid to the substrate processing apparatus 1. The processing fluid supplying apparatus 60 includes a circulation line 62, a gas supply line 61, a cooling section (condenser 68), a pump 70, a branch line 63, a heating section (spiral heater 74), and a pressure adjusting section (back pressure valve 75). The circulation line 62 circulates the processing fluid. The gas supply line 61 supplies the gaseous processing fluid to the circulation line 62. The cooling section (condenser 68) is provided in the circulation line 62 and cools the gaseous processing fluid to generate a liquid processing fluid. The pump 70 is provided downstream of the cooling section (condenser 68) in the circulation line 62. The branch line 63 is connected downstream of the pump 70 in the circulation line 62 and branches the liquid processing fluid from the branching section 72. The heating section (spiral heater 74) is provided downstream of the branch section 72, and heats the liquid processing fluid to generate a supercritical processing fluid. The pressure adjustment section (back pressure valve 75) is provided downstream of the heating section (spiral heater 74) in the circulation line 62 and upstream of the gas supply line 61, and reduces the pressure of the supercritical processing fluid to generate a gaseous processing fluid. This reduces the effects of pulsation generated by the pump 70 when pumping out the liquid processing fluid with the pump 70.

In the substrate processing system 100 according to the embodiment, the processing fluid supply device 60 is provided between the gas supply line 61 and the cooling section (condenser 68) in the circulation line 62, and further includes a filter 67 for filtering the gaseous processing fluid. This effectively removes foreign matter contained in the processing fluid, and effectively suppresses the generation of particles on the surface of the wafer W during the drying process of the wafer W using the supercritical fluid.

In the substrate processing system 100 according to the embodiment, the processing fluid supply device 60 supplies processing fluid in a liquid state to the substrate processing apparatus 1 from the branch line 63. Thereby, even if variations occur in the distance between the processing fluid supply device 60 and the substrate processing apparatus 1, that is, the length of the connection line 80, problems caused by such variations in length can be reduced.

In the substrate processing system 100 according to the embodiment, the substrate processing apparatus 1 includes another heating section (heater 44) and a substrate processing section (drying unit 18). Another heating unit (heater 44) heats the processing fluid in a liquid state to generate a processing fluid in a supercritical state. The substrate processing section (drying unit 18) processes the substrate (wafer W) with a supercritical processing fluid supplied from another heating section (heater 44). Thereby, it is possible to suppress the pattern from collapsing during the drying process.

In the substrate processing system 100 according to the embodiment, the processing fluid in a supercritical state within the substrate processing section (drying unit 18) has a temperature of 90° C. or higher. Thereby, generation of particles on the surface of the wafer W can be suppressed during the drying process of the wafer W using the supercritical fluid.

In the substrate processing system 100 according to the embodiment, the temperature of the supercritical processing fluid generated in another heating section (heater 44) is higher than the temperature of the processing fluid within the substrate processing section (drying unit 18). Thereby, even if the temperature of the processing fluid decreases due to adiabatic expansion when passing through the orifice 46, the temperature of the processing fluid within the drying unit 18 can be maintained at 90° C. or higher.

<Details of Processing Fluid Supply Process>
Next, the details of the processing fluid supplying process executed by the processing fluid supplying apparatus 60 according to the embodiment will be described with reference to Fig. 12. Fig. 12 is a flowchart showing the processing procedure of the processing fluid supplying process according to the embodiment.

First, the control unit 7 operates the valve 64 and the flow rate regulator 65 to supply gaseous processing fluid from the processing fluid supply source 90 to the circulation line 62 (step S101). Then, the control unit 7 filters the gaseous processing fluid flowing through the circulation line 62 with the filter 67 (step S102).

Next, the control unit 7 cools the gaseous processing fluid filtered by the filter 67 with the condenser 68 to generate a liquid processing fluid (step S103). Then, the control unit 7 stores the liquid processing fluid generated by the capacitor 68 in the tank 69 (step S104).

Next, the control unit 7 pumps the liquid-state processing fluid stored in the tank 69 downstream of the circulation line 62 using the pump 70 (step S105). Then, the control unit 7 branches the liquid-state processing fluid pumped out by the pump 70 from the circulation line 62 to the branch line 63 (step S106).

Next, the control unit 7 heats the processing fluid in a liquid state flowing through the circulation line 62 with the spiral heater 74 to generate a processing fluid in a supercritical state (step S107). Then, the control unit 7 reduces the pressure of the supercritical processing fluid generated by the spiral heater 74 using the back pressure valve 75 to generate a gaseous processing fluid (step S108).

Finally, the control unit 7 merges the gaseous processing fluid generated by the back pressure valve 75 with the gaseous processing fluid supplied from the processing fluid supply source 90 (step S109), completing the process.

The processing fluid supply method according to the embodiment includes a step of supplying (step S101), a step of generating a processing fluid in a liquid state (step S103), a step of branching (step S106), and a step of supplying a processing fluid in a supercritical state. The process includes a step of generating (step S107). In the supplying step (step S101), a gaseous processing fluid is supplied to the circulation line 62. In the step of generating a liquid processing fluid (step S103), the gaseous processing fluid is cooled in the circulation line 62 to generate a liquid processing fluid. In the step of branching (step S106), the liquid processing fluid is branched from the circulation line 62 to the branch line 63. In the step of generating a supercritical processing fluid (step S107), the liquid processing fluid is heated in the circulation line 62 to generate a supercritical processing fluid. This makes it possible to reduce the influence of pulsation that occurs in the pump 70 when the pump 70 pumps out the processing fluid in a liquid state.

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the present disclosure. For example, in the above embodiment, an example was shown in which a back pressure valve 75 was used as a pressure adjustment unit that reduces the pressure of a processing fluid in a supercritical state to generate a processing fluid in a liquid state. However, the pressure adjustment unit is not limited to a back pressure valve, and may be, for example, an orifice.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. Indeed, the embodiments described above may be implemented in various forms. Moreover, the above-described embodiments may be omitted, replaced, or modified in various forms without departing from the scope and spirit of the appended claims.

W Wafer 1 Substrate processing device 18 Drying unit (an example of a substrate processing section)
44 Heater (an example of another heating part)
60 Processing fluid supply device 61 Gas supply line 62 Circulation line 63 Branch line 67 Filter 68 Condenser (an example of a cooling part)
70 Pump 72 Branch part 74 Spiral heater (an example of a heating part)
75 Back pressure valve (an example of pressure regulating part)
100 Substrate processing system

Claims (3)

a circulation line that circulates a processing fluid for processing the substrate;
a gas supply line that supplies the processing fluid in a gaseous state to the circulation line;
a cooling unit that is provided in the circulation line and that cools the processing fluid in a gaseous state to generate the processing fluid in a liquid state;
a pump provided downstream of the cooling section in the circulation line;
a branch line that is connected to the downstream side of the pump in the circulation line and branches the processing fluid in a liquid state from a branch part;
a heating section that is provided downstream of the branch section and that heats the processing fluid in a liquid state to generate the processing fluid in a supercritical state;
In the circulation line, it is provided downstream of the heating section and upstream of the connection between the circulation line and the gas supply line, and reduces the pressure of the processing fluid in a supercritical state to convert the processing fluid into a gaseous state. A pressure regulating section that generates
a valve provided on the downstream side of the pressure regulating section in the circulation line, the valve switching on and off the flow of the processing fluid in the circulation line;
a back pressure valve provided between the branch part and the valve in the branch line;
A control unit that controls each part,
Equipped with
The control unit performs a process of branching the processing fluid in a liquid state from the circulation line to the branch line by fully closing the valve opening of the back pressure valve. The processing fluid supply device. In the process of branching the processing fluid in a liquid state from the circulation line to a branch line, the control unit closes the valve and sets the valve opening degree of the back pressure valve to a fully closed state, and then a predetermined period of time has elapsed. The processing fluid supply device according to claim 1, wherein when the valve is opened, the opening degree of the back pressure valve is changed to a predetermined fixed opening degree. a circulation line that circulates a processing fluid for processing the substrate;
a gas supply line that supplies the processing fluid in a gaseous state to the circulation line;
a cooling unit that is provided in the circulation line and that cools the processing fluid in a gaseous state to generate the processing fluid in a liquid state;
a pump provided downstream of the cooling section in the circulation line;
a branch line that is connected to the downstream side of the pump in the circulation line and branches the processing fluid in a liquid state from a branch part;
a heating section that is provided downstream of the branch section and that heats the processing fluid in a liquid state to generate the processing fluid in a supercritical state;
In the circulation line, it is provided downstream of the heating section and upstream of the connection between the circulation line and the gas supply line, and reduces the pressure of the processing fluid in a supercritical state to convert the processing fluid into a gaseous state. A pressure regulating section that generates
a valve provided on the downstream side of the pressure regulating section in the circulation line, the valve switching on and off the flow of the processing fluid in the circulation line;
A control unit that controls each part,
Equipped with
The control unit continues to maintain the valve in an open state when performing a process of heating the processing fluid in a liquid state in the circulation line to generate the processing fluid in a supercritical state.

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