WO2024024804A1

WO2024024804A1 - Substrate processing method and substrate processing apparatus

Info

Publication number: WO2024024804A1
Application number: PCT/JP2023/027268
Authority: WO
Inventors: 雅之小川
Original assignee: 東京エレクトロン株式会社
Priority date: 2022-07-28
Filing date: 2023-07-25
Publication date: 2024-02-01

Abstract

A substrate processing apparatus according to an embodiment includes: a processing container that is capable of storing a substrate; a processing fluid supply unit that supplies a processing fluid in a supercritical state to the processing container in order to perform supercritical drying processing on the substrate; a fluid discharge unit that discharges the fluid from the processing container and has a discharge channel connected to the processing container and a discharge mechanism provided in the discharge channel; and a control unit that controls at least the processing fluid supply unit and the fluid discharge unit, wherein when the substrate is not stored in the processing container, the control unit performs vacuum cleaning processing where the control unit seals the processing container and prevents the fluid from flowing into the processing container, and in this state the control unit operates the discharge mechanism of the fluid discharge unit to vacuum the processing container, lowers the pressure inside the processing container to a predetermined vacuum cleaning pressure, vaporizes pollutants of the processing container, and discharges the pollutants from the processing container.

Description

Substrate processing method and substrate processing apparatus

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

In the manufacturing process of semiconductor devices in which a laminated structure of integrated circuits is formed on the surface of a substrate such as a semiconductor wafer, liquid processing such as chemical cleaning or wet etching is performed. In recent years, a drying method using a processing fluid in a supercritical state has been used to remove liquid adhering to the surface of a substrate in such liquid processing.

Japanese Patent Application Publication No. 2013-12538

The present disclosure provides a technique that can improve the cleanliness of a substrate after the drying process in a drying process of the substrate using a processing fluid in a supercritical state.

A substrate processing apparatus according to an embodiment of the present disclosure includes a processing container capable of accommodating a substrate, and a processing fluid supply supplying a processing fluid in a supercritical state to the processing container in order to perform supercritical drying processing on the substrate. a fluid discharge section configured to discharge fluid from the processing container, the fluid discharge section having a discharge channel connected to the processing container, and an exhaust mechanism provided in the discharge channel; a control unit that controls the processing fluid supply unit and the fluid discharge unit, the control unit sealing the processing container and controlling the temperature inside the processing container when no substrate is accommodated in the processing container. A state is established in which no fluid flows in, and in this state, the exhaust mechanism of the fluid discharge section is operated to evacuate the processing container, and the pressure inside the processing container is brought to a predetermined vacuum cleaning pressure. A vacuum cleaning process is performed in which the contaminants in the processing container are vaporized and discharged from the processing container.

According to the above embodiments of the present disclosure, in the drying process of a substrate using a processing fluid in a supercritical state, the cleanliness of the substrate after the drying process can be improved.

1 is a diagram of a piping system of a supercritical drying apparatus according to an embodiment of the present disclosure. 1 is a schematic cross-sectional view showing an example of the configuration of a substrate processing system incorporating a supercritical drying device. FIG. 2 is a diagram for explaining an example of a procedure of a vacuum cleaning process executed in a substrate processing system incorporating a plurality of supercritical drying devices. FIG. 2 is a main piping system diagram showing a configuration example in which a vacuum line is directly connected to a processing container.

A supercritical processing apparatus 1 according to an embodiment of the present disclosure will be described with reference to the accompanying drawings. This supercritical processing apparatus can be used to perform a supercritical drying process in which a substrate having a liquid (for example, IPA) attached to its surface is dried using a processing fluid in a supercritical state.

As shown in FIG. 1, the supercritical processing apparatus 1 includes a supercritical processing unit 10 in which supercritical drying processing is performed. The supercritical processing unit 10 includes a processing container 12 and a substrate holding tray 14 (hereinafter simply referred to as "tray 14") that holds a substrate within the processing container 12.

In one embodiment, the tray 14 includes a lid 16 that closes an opening provided in a side wall of the processing container 12, and a horizontally extending substrate support plate (substrate holder) 18 (hereinafter simply referred to as a substrate holder) connected to the lid 16. (referred to as "plate 18"). A substrate W is placed horizontally on the plate 18 with the front surface (device forming surface) facing upward.

The tray 14 can be moved in the horizontal direction between a processing position (closed position) and a substrate transfer position (open position) by a tray movement mechanism (not shown). In the processing position, the plate 18 is located within the internal space of the processing container 12, and the lid 16 closes the opening in the side wall of the processing container 12 (the state shown in FIG. 1). At the substrate transfer position, the plate 18 extends outside the processing container 12, and the substrate W can be transferred between the plate 18 and a substrate transfer arm (not shown). The moving direction of the tray 14 is, for example, the left-right direction in FIG.

When the tray 14 is in the processing position, the internal space of the processing container 12 is divided by the plate 18 into an upper space 12A above the plate 18 where the substrate W exists during processing and a lower space 12B below the plate 18. be done. However, the upper space 12A and the lower space 12B are not completely separated. A gap is formed between the peripheral edge of the tray 14 in the processing position and the inner wall surface of the processing container 12, which serves as a communication path that communicates the upper space 12A and the lower space 12B. Further, in the vicinity of the lid portion 16, a through hole may be provided in the plate 18 to communicate the upper space 12A and the lower space 12B.

As described above, if the internal space of the processing container 12 is divided into the upper space 12A and the lower space 12B, and a communication path is provided that communicates the upper space 12A and the lower space 12B, the tray 14 (Plate 18) may be configured as a substrate mounting table (substrate holder) immovably fixed within processing container 12. In this case, with a lid (not shown) provided on the processing container 12 open, a substrate transfer arm (not shown) enters the container body, and the substrate is transferred between the substrate mounting table and the substrate transfer arm. .

The processing container 12 has a first chamber for receiving pressurized processing fluid, in this embodiment, carbon dioxide in a supercritical state (hereinafter also referred to as "CO2" for convenience). It has a fluid supply section 21 and a second fluid supply section 22.

The first fluid supply section 21 is provided below the plate 18 of the tray 14 in the processing position. The first fluid supply section 21 supplies CO2 into the lower space 12B toward the lower surface of the plate 18. The first fluid supply section 21 can be configured by a through hole formed in the bottom wall of the processing container 12. The first fluid supply section 21 may be a nozzle body attached to the bottom wall of the processing container 12.

The second fluid supply section 22 is provided to be located on the side of the substrate W placed on the plate 18 of the tray 14 in the processing position. The second fluid supply section 22 can be provided, for example, on one side wall (first side wall) of the processing container 12 or in the vicinity thereof. The second fluid supply section 22 supplies CO2 into the upper space 12A toward a region slightly above the substrate W.

The second fluid supply section 22 can be configured with a plurality of discharge ports arranged in a horizontal direction (for example, in a direction perpendicular to the plane of the paper in FIG. 1). More specifically, the second fluid supply section 22 can be formed, for example, as a header made of a horizontally extending pipe-like member with a plurality of holes. The second fluid supply section 22 may be configured to be able to flow CO2 almost evenly over the entire diameter of the substrate W and along the upper surface (surface) of the substrate W. preferable.

The processing container 12 further includes a fluid discharge section 24 that discharges the processing fluid from the internal space of the processing container 12. The fluid discharge section 24, like the second fluid supply section 22, can be formed as a header made of a horizontally extending pipe-like member with a plurality of holes. The fluid discharge part 24 can be provided, for example, on a side wall (second side wall) opposite to the first side wall of the processing container 12 where the second fluid supply part 22 is provided, or in the vicinity thereof.

The fluid discharge section 24 is located at such a position that the CO2 supplied into the processing container 12 from the second fluid supply section 22 is discharged from the fluid discharge section 24 after passing through the area above the substrate W on the plate 18. If so, it can be placed at any position. That is, for example, the fluid discharge section 24 may be provided at the bottom of the processing container 12 near the second side wall. In this case, the CO2 flows through the area above the substrate W in the upper space 12A, and then passes through the communication path provided at the peripheral edge of the plate 18 (or through the through hole formed in the plate 18). After flowing into the lower space 12B, it is discharged from the fluid discharge section 24.

Next, a supply/discharge system that supplies and discharges CO2 to and from the processing container 12 in the supercritical processing apparatus will be described. In the piping system diagram shown in FIG. 1, the member indicated by a circled T is a temperature sensor, and the member indicated by a circled P is a pressure sensor. The member designated with the symbol OLF is an orifice (fixed throttle), which lowers the pressure of CO2 flowing in the pipe on the downstream side to a desired value. The member indicated by SV surrounded by a square is a safety valve (relief valve), which prevents components of the supercritical processing apparatus such as piping or processing vessel 12 from being damaged due to unexpected excessive pressure. The member labeled with F is a filter, which removes pollutants such as particles contained in CO2. The member labeled CV is a check valve. The member indicated by FV in a circle is a flow meter. The member indicated by H surrounded by a square is a heater for controlling the temperature of CO2. A member with reference symbol VN (N is a natural number) is an on-off valve, and ten on-off valves V1 to V11 are depicted in FIG.

The supercritical processing apparatus 1 has a supercritical fluid supply device (processing fluid supply section) 30. In this embodiment, the supercritical fluid is carbon dioxide in a supercritical state (hereinafter also referred to as "supercritical CO2"). The supercritical fluid supply device 30 has a well-known configuration including, for example, a carbon dioxide cylinder, a pressure pump, a heater, and the like. The supercritical fluid supply device 30 has the ability to send out supercritical CO2 at a supercritical state guarantee pressure (specifically, about 16 MPa), which will be described later, or a pressure higher than that.

A main supply line 32 is connected to the supercritical fluid supply device 30. CO2 flows from the supercritical fluid supply device 30 into the main supply line 32 in a supercritical state, but may also become a gaseous state due to subsequent expansion or temperature changes. In this specification, a member called a "line" can be constituted by a pipe (piping member).

The main supply line 32 branches into a first supply line 34 and a second supply line 36 at a branch point 33. The first supply line 34 is connected to the first fluid supply section 21 of the processing container 12 . The second supply line 36 is connected to the second fluid supply section 22 of the processing container 12 .

A discharge line 38 is connected to the fluid discharge section 24 of the processing container 12. The discharge line 38 is provided with a pressure regulating valve (back pressure valve) 40. By adjusting the opening degree of the pressure regulating valve 40, the primary side pressure of the pressure regulating valve 40 can be adjusted, and therefore the pressure inside the processing container 12 can be adjusted.

The control unit 300 schematically shown in FIG. The opening degree (specifically, the position of the valve body) of the pressure regulating valve 40 is feedback-controlled so as to be maintained. As a measurement value of the pressure inside the processing container 12, for example, as shown in FIG. The detected value of can be used. In other words, the pressure inside the processing container 12 may be measured directly by a pressure sensor provided inside the processing container 12, or indirectly by a pressure sensor (PS) provided outside the processing container 12 (discharge line 38). may be measured.

The control unit 300 is, for example, a computer, and includes a calculation unit 301 and a storage unit 302. The storage unit 302 stores programs that control various processes executed in a supercritical processing apparatus (or a substrate processing system including a supercritical processing apparatus). The calculation unit 301 controls the operation of the supercritical processing apparatus by reading and executing a program stored in the storage unit 302. The program may be one that has been recorded on a computer-readable storage medium, and may be installed in the storage unit 302 of the control unit 300 from the storage medium. Examples of computer-readable storage media include hard disks (HD), flexible disks (FD), compact disks (CD), magnetic optical disks (MO), and memory cards.

A bypass line 44 branches off from the first supply line 34 at a branch point 42 set on the first supply line 34 . The bypass line 44 is connected to the exhaust line 38 at a connection point 46 set in the exhaust line 38 . Connection point 46 is upstream of pressure regulating valve 40 .

A vacuum line 50 branches from the discharge line 38 at a branch point 48 set in the discharge line 38 on the upstream side of the pressure regulating valve 40. The downstream end of the vacuum line 50 is a discharge destination during normal operation of the supercritical processing apparatus 1 (normal operation discharge destination), for example, it is open to the atmospheric space outside the supercritical processing apparatus, or a factory exhaust duct. It is connected to the.

At a branch point 52 set in the discharge line 38, two vacuum lines 54 and 56 branch off from the discharge line 38. The downstream ends of the vacuum lines 54 and 56 join the discharge line 38 again. The downstream end of the exhaust line 38 can be connected to, for example, an factory exhaust duct (EXH). Alternatively, the downstream end of the exhaust line 38 may be connected to the factory exhaust duct (EXH) via a fluid recovery device (not shown). Useful components (for example, IPA (isopropyl alcohol)) contained in the CO2 recovered by the fluid recovery device are appropriately separated and reused.

A purge gas supply line 62 is connected to a confluence point 60 set in the first supply line 34 between the branch point 42 and the processing container 12. A purge gas (for example, nitrogen (N2) gas) can be supplied to the processing container 12 from a purge gas supply source 63 via a purge gas supply line 62 . The purge gas supply source 63 may be provided for factory use in a semiconductor device manufacturing factory.

An exhaust line 66 branches off from a branch point 64 set in the main supply line 32 immediately upstream of the branch point 33.

At a branch point 70 set in the discharge line 38, a vacuum line 71 branches off from the discharge line 38. At a branch point 72 set in the vacuum line 71, the vacuum line 71 branches into a first sub-vacuum line 73 and a second sub-vacuum line 74. A first vacuum pump 75 as a first evacuation device is interposed in the first sub-evacuation line 73 . A second vacuum pump 76 as a second evacuation device is interposed in the second sub-evacuation line 74 .

The first vacuum pump 75 has a roughing function that lowers the pressure in the space to be depressurized (here, the internal space of the processing container 12) from normal pressure to a pressure at which the second vacuum pump can operate. The second vacuum pump 76 has a function of reducing the pressure of the space to be depressurized to a desired processing pressure (vacuum cleaning pressure) after the first vacuum pump 75 has reduced the pressure of the space to be depressurized. The first vacuum pump 75 is, for example, a rotary pump (RP), and the second vacuum pump 76 is, for example, a turbo molecular pump (TMP).

The part of the discharge line 38 upstream of the branch point 70 (processing vessel 12 side) is the part of the discharge line 38 downstream of the branch point 70 (this is referred to as the "downstream discharge line" in FIGS. 3A to 3G). A first switching device 79 is provided for selectively communicating with either the vacuum pump line 71 (corresponding to "38D") or the vacuum suction line 71. This first switching device 79 may be a three-way valve provided at the branch point 70. The first switching device 79 connects an on-off valve provided in the discharge line 38 near the branch point 70 and on the downstream side of the branch point 70 and an on-off valve provided on the evacuation line 71 near the branch point 70. It may be a combination. At least one of the existing on-off valves (eg, V5 to V8) may be used to realize the function of the first switching device 79. To simplify the drawing, the first switching device 79 is schematically represented by a box surrounding the branch point 70.

A second switching device 80 is provided to selectively connect the vacuum line 71 to either the first sub-vacuum line 73 or the second sub-vacuum line 74. The second switching device 80 may be one three-way valve like the first switching device 79, and may be connected to the first sub-vacuum line 73 and the second sub-vacuum line 74 in the vicinity of the branch point 70, respectively. It may be a combination of a plurality of on-off valves provided. The second switching device 80 is also schematically represented by a box surrounding the branch point 72.

Next, the substrate drying method performed using the above supercritical processing apparatus will be briefly explained. Note that the substrate drying method described below is a well-known method per se, and therefore only a brief explanation will be provided. For details, please refer to, for example, the patent publication publication No. 2022-069237 related to the earlier application filed by the applicant.

First, a substrate W having an IPA puddle (IPA liquid film) formed on its surface is placed on the tray 14 pulled out from the processing container 12, and then the tray 14 is accommodated in the processing container 12. .

[Boosting process]
First, a pressure increasing step is performed. CO2 (carbon dioxide), which is a processing fluid, is supplied from the supercritical fluid supply device 30 into the processing container 12 via the main supply line 32, the first supply line 34, and the first fluid supply section 21. Since the pressure inside the processing container 12 is low for a while after the supply starts, CO2 flows into the processing container 12 in a gaseous state and at a high flow rate. The inflowing CO2 gas collides with the plate 18 and then spreads into the processing container 12. By continuing this state for a while, the pressure inside the processing container 12 increases. At the beginning of this pressurization process, a part of the CO2 flowing through the main supply line 32 is allowed to flow into the exhaust line 66, or a part of the CO2 flowing through the first supply line 34 is passed through the bypass line 44 to the exhaust line 38. By allowing the CO2 to flow into the processing container 12, the flow rate of CO2 flowing into the processing container 12 can be suppressed.

When the pressure within the processing container 12 exceeds the critical pressure of CO2 (approximately 8 MPa), the CO2 (CO2 not mixed with IPA) present within the processing container 12 becomes supercritical. When the CO2 in the processing container 12 becomes supercritical, IPA on the substrate W begins to dissolve into the supercritical CO2. After the pressure in the processing container 12 exceeds the critical pressure of CO2, the CO2 in the processing container 12 is maintained in a supercritical state regardless of the IPA concentration and temperature in the mixed fluid (CO2 + IPA) on the substrate W. The above pressure increasing step is continued until the pressure reaches a guaranteed pressure (supercritical state guaranteed pressure). The supercritical state guarantee pressure is approximately 16 MPa.

[Distribution process]
When the pressure inside the processing container 12 reaches the above-mentioned supercritical state guarantee pressure, the supply of CO2 from the first fluid supply section 21 to the processing container 12 is stopped, and instead, the supply of CO2 from the second fluid supply section 22 to the processing container 12 is stopped. Start supplying CO2 into the tank. By feedback controlling the opening degree of the pressure regulating valve 40, the pressure inside the processing container 12 is maintained at a predetermined pressure that is slightly higher than the supercritical state guarantee pressure.

The supercritical CO2 supplied into the processing container 12 from the second fluid supply section 22 flows in the area above the substrate, and is then discharged from the fluid discharge section 24. At this time, a laminar flow of supercritical CO2 flowing approximately parallel to the surface of the substrate W is formed in the processing chamber 12. IPA in the mixed fluid (IPA+CO2) on the surface of the substrate W exposed to the laminar flow of supercritical CO2 is replaced by supercritical CO2. Eventually, almost all of the IPA on the surface of the substrate W is replaced with supercritical CO2.

When the replacement of IPA with supercritical CO2 is completed, the supply of CO2 to the processing container 12 is stopped and the exhaust line 38 of the processing container 12 is connected to the atmosphere, thereby lowering the pressure of the processing container 12 to normal pressure. . As a result, the supercritical CO2 present in the pattern of the substrate W becomes a gas and leaves the pattern, and the gaseous CO2 is discharged from the processing container 12. With the above steps, drying of the substrate W is completed. The dried substrate W is carried out from the processing container 12.

When the above-mentioned supercritical drying process is repeated, contaminants may adhere to the surfaces of the members facing the atmosphere of the processing container 12 (for example, the inner wall surface of the processing container 12, the surface of the tray 14, etc., where the flow rate of the processing fluid is slow). do. Contaminants include those derived from organic matter (for example, higher fatty acids) dissolved in the IPA paddle on the surface of the substrate W, those derived from moisture flowing into the processing container 12 when the tray 14 is opened and closed, and those derived from the adhesion of the substrate W. Kimono (for example, those derived from chemical components that adhered to the back surface of the substrate W during liquid processing, which is a pretreatment of supercritical drying processing. Such contaminants are There is a risk that the substrate W may be contaminated by the substrate W.A vacuum cleaning process for cleaning the inside of the processing container 12 in order to prevent the substrate W from being contaminated will be described below.

With no substrate W accommodated in the processing container 12, the tray 14 is located at the processing position, that is, the closed position, and the inside of the processing container 12 is sealed. In this state, at least the on-off valves V1, V2, V4, and V11 are closed to prevent any fluid from flowing into the processing container 12. Further, the first switching device 79 connects the processing container 12 and the evacuation line 71, and the second switching device 80 connects the evacuation line 71 and the first sub-evacuation line 73.

In this state, the first vacuum pump 75 (ie, rotary pump RP) is driven, and the inside of the processing container 12 is thereby evacuated to a first pressure (for example, a medium vacuum of about 1 Pa). Next, the second switching device 80 connects the evacuation line 71 and the second sub-evacuation line 74, and the second vacuum pump 76 (ie, turbo molecular pump TMP) is driven. As a result, the inside of the processing container 12 is evacuated to a second pressure lower than the first pressure (for example, a high vacuum of about 1×10 ⁻⁵ Pa).

As a result, the aforementioned contaminants are evaporated (vaporized) and are removed from the surface to which they were attached. Since the inside of the processing container 12 is suctioned by the second vacuum pump 76, contaminants are discharged from the processing container 12 through the discharge line 38, the evacuation line 71, and the second sub-evacuation line 74. By continuing this state for a predetermined period of time, the surface to which contaminants have adhered is cleaned.

Note that even while the inside of the processing container 12 is being evacuated by the first vacuum pump 75, contaminants that are easily evaporated are separated from the surface to which they were attached and are discharged from the processing container 12. . While the inside of the processing container 12 is being evacuated by the second vacuum pump 76, substances that do not evaporate at the degree of vacuum achieved by the first vacuum pump 75 are removed.

Note that the processing container 12 is provided with a heater H (schematically shown in FIG. 1). The heater H is, for example, embedded in the wall of the processing container or attached to the surface of the wall. This heater H is used for temperature control to maintain CO2 in a supercritical state during the supercritical drying process. By operating this heater H, evaporation can be promoted and the removal efficiency of contaminants can be increased. In this case, a vacuum bake cleaning process will be performed.

For the processing pressure and processing temperature (pressure and temperature inside the processing container 12) during the vacuum cleaning process (vacuum bake cleaning process), refer to the vapor pressure diagram of the contaminant to be removed (for example, the vapor pressure diagram of COX). can be determined. The processing pressure and processing temperature should be such that the most difficult to remove adhering substances (contaminants) that can be removed by vacuum cleaning processing (vacuum bake cleaning processing) can be reliably removed within the desired processing time. Bye. For example, processing conditions such as 100° C. and 1×10 ⁻⁵ Pa are exemplified, and under these conditions, it is possible to remove most of the problematic adhering substances within the processing container 12 of the supercritical drying apparatus. The cleaning time can be shortened as the cleaning treatment conditions are higher temperature and lower pressure conditions that are further away from the vapor pressure diagram of the contaminant to be removed. However, if high temperature and low pressure are used, the energy cost during the vacuum cleaning process (vacuum bake cleaning process) increases, so an appropriate vacuum cleaning process may be determined depending on the required vacuum cleaning process time. Note that the vacuum cleaning process (vacuum bake cleaning process) can be performed immediately after the substrate W has been subjected to the supercritical drying process and the substrate W has been taken out. In this case, the heater H does not need to be operated. The temperature of the processing container 12 is sufficiently high due to the residual heat. Therefore, there is a possibility that processing can be performed at higher pressure (lower vacuum).

After the vacuum cleaning process (or vacuum bake cleaning process) is completed, the supercritical processing equipment is returned to the standby state for normal processing. That is, the evacuation of the processing container 12 is stopped and the pressure inside the processing container 12 is returned to normal pressure. An example of the procedure will be explained. First, the first vacuum pump 75 and the second vacuum pump 76 are stopped, and the first switching device 79 cuts off communication between the part of the discharge line 38 upstream of the branch point 70 and the vacuum line 71, and branches A portion upstream from point 70 and a portion downstream from point 70 are communicated. The on-off valves V1, V2, V3, V4, V9, V10, and V11 are kept closed. The states of the on-off valves V5, V6, V7, and V8 are arbitrary. From this state, in order to return the inside of the processing container 12 to normal pressure, the on-off valve V11 is opened, and nitrogen gas as a purge gas is supplied from the purge gas supply source 63 to the purge gas supply line 62, the first supply line 34, and the first fluid supply section. 21 into the processing container 12.

It is preferable that the nitrogen gas supplied from the purge gas supply source 63 for factory use is purified by an inert gas purification device (purification device) and then supplied to the purge gas supply line 62. Thereby, it is possible to prevent the processing container 12 from being contaminated by impurity components contained in the purge gas after the vacuum cleaning process described below.

When the pressure inside the processing container 12 detected by the pressure sensor PS provided in the discharge line 38 near the processing container 12 reaches normal pressure, the on-off valve V11 is closed to stop the supply of nitrogen gas as a purge gas. Good too. Alternatively, the on-off valve V3 may be opened while continuing the supply of nitrogen gas (in this case, for example, the on-off valve V8 may be opened) to allow the nitrogen gas to pass through the processing container 12. If the tray 14 is moved to the open position and the substrate W is loaded into the processing container 12 immediately after the pressure inside the processing container 12 becomes normal pressure, nitrogen gas is continued to be supplied without opening the on-off valve V3. You can. By doing so, the nitrogen gas that has flowed into the processing container 12 will flow out from the opening for loading and unloading the substrate in the processing container 12, thereby preventing air containing moisture from flowing into the processing container 12. Can be done. In this case, the supply of nitrogen gas can be stopped, for example, when the tray 14 on which the substrate W is placed moves to the closed position. The above description regarding opening and closing of the on-off valve V3 will be referred to later in the description with reference to FIG. 3E.

Note that if the inside of the processing container 12 is communicated with, for example, a space having an atmospheric atmosphere while the pressure inside the processing container 12 is lower than normal pressure after the vacuum cleaning process is finished, there is a risk that air may flow into the processing container 12. . Particularly, for example, when the on-off valve V3 of the discharge line 38 is opened, gas (for example, air) in the discharge line 38 on the downstream side of the on-off valve V3 flows back into the processing container 12, and the particles in the discharge line 38 are There is a possibility that it will flow into the processing container 12 together with the water. In order to prevent such a situation, when the internal space of the processing container 12 is communicated with an atmosphere with a higher pressure (for example, atmospheric atmosphere), the pressure inside the processing container 12 should be set to normal pressure or higher pressure. is preferred.

Instead of the nitrogen gas mentioned above, CO2 supplied from the supercritical fluid supply device 30 may be used as the purge gas. In this case, instead of opening the on-off valve V11, the on-off valve V9 and the on-off valve V1 or V2 may be opened.

Note that the vacuum cleaning process may be performed, for example, every time the processing of one lot of substrates W is completed, or every time the processing of a predetermined number of substrates W is completed. The execution frequency of the vacuum cleaning process is not limited to this, and can be determined as appropriate according to the process schedule of the supercritical processing unit 10.

As shown in FIG. 2, the above supercritical processing apparatus 1 can be incorporated into, for example, a substrate processing system (substrate processing apparatus) 400 shown in FIG. The substrate processing system 400 will be briefly described below.

The substrate processing system 400 includes a loading/unloading station 102 and a processing station 103.

The loading/unloading station 102 includes a load port 111 and a transport block 112. A plurality of carriers C are placed on the load port 111. Each carrier C accommodates a plurality of substrates W (for example, semiconductor wafers) in a horizontal position at intervals in the vertical direction.

A transport device 113 and a delivery unit 114 are provided within the transport block 112. The delivery unit 114 includes an unprocessed substrate platform on which one or more unprocessed substrates W (substrates W before being processed at the processing station 103) are temporarily placed, and one or more unprocessed substrates. It has a processed substrate mounting section on which a processed substrate W (substrate W processed at the processing station 103) is temporarily placed. The transport device 113 can transport the substrate W between an arbitrary carrier C placed on the load port 111 and the delivery unit 114.

The processing station 103 includes a transport block 104 and a pair of processing blocks 105 provided on both sides of the transport block 4 in the Y direction. Each processing block 105 is provided with a liquid processing unit 200, a supercritical processing unit 10, and a processing fluid supply cabinet 119. In this embodiment, the liquid processing unit 200 and the supercritical processing unit 10 are single-wafer processing units. A processing fluid necessary for processing is supplied from the processing fluid supply cabinet 119 to the liquid processing unit 200 and the supercritical processing unit 10 .

The transport block 104 includes a transport area 115 and a transport device 116 disposed within the transport area 115. The transport device 116 can transport the substrate W between the delivery unit 114, any liquid processing unit 200, and any supercritical processing unit 10.

Each processing block 105 has a multi-layer (for example, three-layer) structure. In this case, each layer is provided with one liquid processing unit 200, one supercritical processing unit 10, and one processing fluid supply cabinet 119. In this case, one transport device 116 may be able to access the liquid processing units 200 and supercritical processing units 10 of all layers.

The overall operation of the substrate processing system 400 is controlled by the aforementioned control unit (control device) 300 (see FIG. 1).

Next, the transport flow of the substrate W in the substrate processing system 400 described above will be briefly described.

An external transfer robot (not shown) places a carrier C containing an unprocessed substrate W on the load port 111. The transport device 113 takes out one substrate W from the carrier C and carries it into the delivery unit 114. The transport device 116 takes out the substrate W from the delivery unit 114 and carries it into the liquid processing unit 200.

Within the liquid processing unit 200, liquid processing consisting of a plurality of steps is performed. The liquid processing unit 200 is, for example, a rotary single-wafer type liquid processing unit well known in the technical field of semiconductor manufacturing equipment. In the liquid processing unit 200, the substrate W is subjected to liquid processing by supplying a processing liquid to the surface of the substrate W, which is held and rotated by a spin chuck. The liquid treatment includes, for example, a chemical treatment step, a rinsing step, an IPA replacement step, and an IPA paddle forming step. In the chemical treatment process, a chemical solution for cleaning or wet etching the surface of the substrate is supplied, in the rinsing process, for example, DIW is supplied as a rinsing liquid, in the IPA replacement process, the rinsing liquid is replaced with IPA, and in the IPA paddle forming process, An IPA paddle of desired thickness is formed. As long as an IPA liquid film (also called an IPA puddle) of a predetermined thickness is formed on the surface of the substrate W in the final step, the steps before that are optional.

Next, the substrate W with the IPA paddle formed on the surface is taken out from the liquid processing unit 200 by the transport device 116 and carried into the supercritical processing unit 10. In the supercritical processing unit 10, the substrate W is dried in the above-described procedure using supercritical drying technology. Thereafter, the transport device 116 takes out the dried substrate W from the supercritical processing unit 10 and transports it into the delivery unit 114. The transport device 13 takes out the substrate W from the delivery unit 114 and stores it in the original carrier C placed on the load port 111. With the above steps, a series of processes for one substrate is completed.

The substrate processing system 400 includes one first vacuum pump 75 and one second vacuum pump 76 that are shared by a plurality of supercritical processing units 10. The first vacuum pump 75 and one second vacuum pump 76 can be housed in a pump chamber 120 between the processing fluid supply cabinets 119, for example.

Next, with reference to FIGS. 3A to 3G, among the operations of the plurality of supercritical processing units 10 and the first vacuum pump 75 and second vacuum pump 76, the process of evacuation of the processing container 12 of each supercritical processing unit 10 will be explained. Only the relevant parts will be extracted and explained. 3A to 3G schematically show the main parts of the piping configuration on the downstream side of the processing vessels 12 (SCC1 to SCC3) of the supercritical processing unit 10. In addition, in FIGS. 3A to 3G, one first vacuum pump 75 and one second vacuum pump 76 are shared by three supercritical processing units 10 (processing vessels 12) to simplify the drawings. However, even if the number of supercritical processing units 10 increases, the basic operation remains the same.

As shown in FIG. 3A, a discharge line 38 connected to the processing vessel 12 of each supercritical processing unit 10, a vacuum line 71 branching from there, a first sub vacuum line 73 and a second sub vacuum line 73 branching from there. Vacuum line 74 is provided in the same manner as shown in FIG. In the embodiment shown in FIG. 3A, a plurality of first sub-evacuation lines 73 merge to form a first combined evacuation line 73M, and a first vacuum pump (RP) 75 is provided in this first combined evacuation line 73M. ing. Further, the plurality of second sub-evacuation lines 74 merge to form a second combined evacuation line 74M, and a second vacuum pump (TMP) 76 is provided in this first combined evacuation line 74M. An operational example of this configuration will be described below. In the following description, for simplicity of notation, the portion of the discharge line 38 upstream of the branch point 70 (first switching device 79) will be referred to as the upstream discharge line 38U, and the branch point of the discharge line 38. The portion downstream from 70 (first switching device 79) is also referred to as downstream discharge line 38D.

3A to 3G, among the lines 71, 73, 74, 73M, and 74M, the parts indicated by thin solid lines are under normal pressure (atmospheric pressure) or under normal pressure that changes depending on the pressure inside the processing container 12. The shaded area means medium vacuum (approximately 1 Pa pressure), and the thick solid line indicates high vacuum (1 x 10 ^-5 This means that the pressure is on the order of Pa.

FIG. 3A shows a case where all supercritical processing units 10 are in a normal operating state. At this time as well, the first vacuum pump 75 and one second vacuum pump 76 are in operation, all the vacuum lines 71 and the first sub-vacuum line 73 are at medium vacuum, and all the second The sub-vacuum line 74 is in high vacuum.

From the state of FIG. 3A, the normal operation of one supercritical processing unit 10 (hereinafter also referred to as "unit SCC1") is stopped, and the supercritical processing unit 10 is vacuum cleaned. First, the substrate W is taken out from the processing container 12 of the unit SCC1, and then the tray 14 is moved to the closed position and the processing container 12 is sealed.

Next, the first switching device 79 corresponding to the unit SCC1 is switched to connect the processing chamber 12 of the unit SCC1 to the first vacuum pump (RP) 75. As a result, the pressure in the processing container 12 and the upstream discharge line 38U associated with the unit SCC1 is reduced to a medium vacuum (see FIG. 3B). Immediately before switching of the first switching device 79, the three vacuum lines 71, the three first sub vacuum lines 73, and the first combined vacuum line 73M are in a medium vacuum state. In other words, a space having a certain volume has already been made into a medium vacuum. Therefore, compared to a case where this is not the case, the time required to reduce the pressure of the processing container 12 and the upstream discharge line 38U related to the unit SCC1 to medium vacuum can be shortened.

Next, from the state shown in FIG. 3B, the second switching device 80 corresponding to the unit SCC1 is switched to communicate the processing chamber 12 of the unit SCC1 with the second vacuum pump (TMP) 76. As a result, the pressure in the processing container 12, upstream discharge line 38U, and vacuum line 71 associated with the unit SCC1 is reduced to a high vacuum (see FIG. 3C). Immediately before switching of the second switching device 80, the three second sub vacuum lines 74 and the second combined vacuum line 74M are in a high vacuum state. In other words, a space having a certain volume is already in a high vacuum. Therefore, compared to a case where this is not the case, the time required to reduce the pressure of the processing container 12, the upstream discharge line 38U, and the vacuum line 71 related to the unit SCC1 to a high vacuum can be shortened.

By continuing the state shown in FIG. 3C for a predetermined period of time, the inside of the processing container 12 of the unit SCC1 is cleaned according to the principle explained above. At this time, as described above, cleaning efficiency can be improved by heating the processing container 12 with the heater attached to the processing container 12. Generally, the processing vessel 12 of the supercritical processing unit 10 is formed of a metal block with a relatively large mass, and is heated to a relatively high temperature during normal operation to maintain the supercritical state of the processing fluid. Maintained. Therefore, the temperature of the processing vessel 12 will not drop significantly unless the operation of the supercritical processing unit 10 is stopped for a relatively long period of time. Therefore, it is not necessarily necessary to operate the heater attached to the processing container 12 during the vacuum cleaning process.

Once the cleaning of the inside of the processing container 12 of the unit SCC1 is completed, it may be left in the state shown in FIG. 3C until the time when the next substrate W is scheduled to be processed in the unit SCC1. By maintaining the inside of the processing container 12 of the unit SCC1 in a vacuum state, the inside of the processing container 12 can be maintained in a clean state.

Next, when the time when the substrate W is scheduled to be processed in the unit SCC1 arrives, as shown in FIG. 3D, the second switching device 80 corresponding to the unit SCC1 is switched and the first vacuum pump (RP) 75 is evacuated. It is connected to line 71. Thereafter, although not shown in FIG. 3D, as previously described with reference to FIG. 1, the on-off valve V3 of the discharge line 38 (38U) is closed. Next, for example, nitrogen gas is supplied as a purge gas into the processing container 12 to return the processing container 12 to normal pressure, and the first switching device 79 corresponding to SCC1 is switched to discharge the processing container 12 of the unit SCC1 to the downstream side. Connect it to line 38D. Thereafter, the on-off valve V3 of the discharge line 38 (38U) may be opened at an appropriate timing. If the on-off valve V3 is opened immediately after the processing container 12 is returned to normal pressure, the state shown in FIG. 3E will occur. Regarding opening and closing of the on-off valve V3 at this time, please refer to the explanation given earlier with reference to FIG. 1.

In the above explanation, the case where only one (SCC1) of the plurality of supercritical processing units 10 is vacuum cleaned is explained, but the same procedure as above is also applied when vacuum cleaning the plurality of supercritical processing units 10. Bye. That is, starting from the state shown in FIG. 3A, the first switching device 79 and the second switching device 80 are sequentially brought into the states shown in FIGS. 3F and 3G, thereby controlling the two supercritical processing units 10 (SCC2 and SCC3). Can be vacuum cleaned.

In the above embodiment, in order to evacuate the inside of the processing container 12 of the supercritical processing unit 10, the vacuum line 71 branched from the discharge line 38 used during normal supercritical drying processing is used, but the invention is not limited to this. . For example, as shown in FIG. 4, a vacuum line 71 is provided separately from the discharge line 38, and this vacuum line 71 is directly connected to the processing container 12, and this vacuum line 71 is connected to the first subsystem. It may be branched into a vacuum line 73 and a second sub-vacuum line 74. The on-off valve V12 provided in the evacuation line 71 is kept closed during normal operation of the supercritical processing unit 10. The on-off valve V12 is opened when performing the vacuum cleaning process, and is closed when the vacuum cleaning process is completed, and then nitrogen purge is performed to return the inside of the processing container to normal pressure. The on-off valve V3 (not shown in FIG. 4, see FIG. 1) of the discharge line 38 is kept closed when the vacuum cleaning process is being performed, and is opened as necessary when the vacuum cleaning process is finished. .

It is also possible to connect the evacuation line (71) for vacuum cleaning processing to a line for supplying supercritical fluid to the processing container 12 (for example, supply lines 34, 36, etc.). However, if this is done, there is a possibility that gas derived from contaminants generated during the vacuum cleaning process may flow into a line located upstream of the processing container 12 in the flow direction of fluid during the supercritical drying process. For this reason, it is preferable to connect the vacuum line (71) to a line (for example, lines 38, 50, etc.) located downstream of the processing container 12 with respect to the fluid flow direction during the supercritical drying process.

If the processing temperature of the vacuum cleaning treatment (vacuum bake cleaning treatment) is set high (for example, 200° C. or higher), a certain degree of cleaning effect can be expected even in a medium vacuum. In this case, for example, if the first vacuum pump 75 is a rotary pump capable of achieving a medium vacuum of about 1 Pa, it is not necessary to provide the second vacuum pump 76 for achieving a high vacuum. When vacuum cleaning processing (vacuum bake cleaning processing) is performed at a high processing temperature (for example, 200° C. or higher) as described above, it is preferable that the pressure inside the processing container 12 is set to, for example, 1 Pa or lower. When vacuum cleaning processing (vacuum bake cleaning processing) is performed without raising the processing temperature (for example, from room temperature to about 100° C.), the pressure inside the processing container 12 may be set to, for example, 1×10 ⁻² Pa or less. preferable.

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

The substrate is not limited to a semiconductor wafer, and may be any other type of substrate used in the manufacture of semiconductor devices, such as a glass substrate or a ceramic substrate.

12 Processing container 30 Processing fluid supply section 38, 71, 73, 74 Discharge channel 75, 76 Discharge mechanism 300 Control section

Claims

a processing container capable of accommodating a substrate;
a processing fluid supply unit that supplies a processing fluid in a supercritical state to the processing container in order to perform supercritical drying processing on the substrate;
a fluid discharge section that discharges fluid from the processing container, the fluid discharge section having a discharge channel connected to the processing container and an exhaust mechanism provided in the discharge channel;
a control unit that controls at least the processing fluid supply unit and the fluid discharge unit;
Equipped with
The control section is configured to seal the processing container and to prevent fluid from flowing into the processing container when no substrate is housed in the processing container, and in this state, to control the exhaust of the fluid discharge section. By operating a mechanism, the processing container is evacuated, the pressure inside the processing container is reduced to a predetermined vacuum cleaning pressure, and the contaminants in the processing container are vaporized and discharged from the processing container. Substrate processing equipment that performs vacuum cleaning processing.
5. The method further comprises a heater that heats the processing container, and the control unit heats the processing container with the heater to promote vaporization of contaminants in the processing container when performing the vacuum cleaning process. 1. The substrate processing apparatus according to 1.
The exhaust mechanism of the fluid discharge section includes a first exhaust device and a second exhaust device, and the first exhaust device reduces the pressure in the processing container from normal pressure to a pressure at which the second exhaust device can operate. The second exhaust device has a function of reducing the pressure in the processing container to the vacuum cleaning pressure after the pressure in the processing container is reduced by the first exhaust device. The substrate processing apparatus according to claim 1.
The substrate processing apparatus according to claim 3, wherein the first exhaust device is a rotary pump, and the second exhaust device is a turbomolecular pump.
The discharge flow path includes a discharge line connected to the processing container and for discharging the processing fluid from the processing container to a discharge destination during normal operation, and a vacuum line branched from the discharge line at a first branch point. line, the exhaust mechanism communicates with the processing container via the vacuum line,
A normal exhaust state in which the fluid that has flowed down the discharge line does not flow into the vacuum line and flows down to the discharge destination during the normal operation, and a fluid that has flowed down the discharge line does not flow into the vacuum line during the normal operation. 2. The substrate processing apparatus according to claim 1, further comprising a first switching device for switching between a cleaning exhaust state in which the cleaning exhaust gas flows into the vacuum line without flowing down to a discharge destination.
The vacuum line is branched into a first sub-vacuum line and a second sub-vacuum line at a second branch point,
The exhaust mechanism includes a first exhaust device and a second exhaust device, and the first exhaust device reduces the pressure within the processing container from normal pressure to an operable pressure at which the second exhaust device can operate. has a rough evacuation function, and the second exhaust device has a function of reducing the pressure in the processing container to the vacuum cleaning pressure after reducing the pressure in the processing container by the first exhaust device,
The first evacuation device is provided in a first sub-evacuation line, the second evacuation device is provided in a second sub-evacuation line,
A first state in which the fluid flowing down the evacuation line does not flow into the second sub-evacuation line but flows into the first sub-evacuation line, and a fluid flowing down the evacuation line is 6. The substrate processing apparatus according to claim 5, further comprising a second switching device for switching between a second state in which the substrate does not flow into the first sub-evacuation line but flows into the second sub-evacuation line.
The substrate processing apparatus includes a plurality of processing containers, one first exhaust device and one second exhaust device that are commonly used to evacuate the plurality of processing containers,
The discharge flow path, the vacuum line, the first sub-vacuum line, and the second sub-vacuum line are connected to each of the processing containers, and therefore, the substrate processing apparatus has a plurality of sub-vacuum lines. One sub-vacuum line and a plurality of second sub-vacuum lines are provided,
The downstream ends of the plurality of first sub vacuum lines are merged to form a first combined vacuum line, and the first combined vacuum line is provided with the one first exhaust device,
The downstream ends of the plurality of second sub vacuum lines are merged to form a second combined vacuum line, and the second combined vacuum line is provided with the one second exhaust device.
The substrate processing apparatus according to claim 6.
The control unit includes:
During normal operation of the substrate processing apparatus,
By controlling the first exhaust device, the second exhaust device, the first switching device, and the second switching device, the fluid flowing down the discharge line is prevented from flowing into the vacuum line and is During operation, the exhaust is in a normal exhaust state flowing down to the exhaust destination, and all the first sub vacuum lines and the first combined vacuum line are maintained at the operable pressure, and all the second vacuum lines are maintained at the operable pressure. maintaining the vacuum cleaning pressure in the sub-vacuum line and the second combined vacuum line;
When vacuum cleaning processing is performed in at least one of the plurality of processing vessels,
By controlling the first exhaust device, the second exhaust device, the first switching device, and the second switching device,
The first evacuation device is communicated with the processing container in which the vacuum cleaning process is performed, and the inside of the processing container is moved through the discharge line, the evacuation line, and the first sub-evacuation line corresponding to the processing container. the operable pressure;
After that, the second evacuation device is communicated with the processing container in which the vacuum cleaning process is performed, and the processing container is connected to the processing container via the discharge line, the evacuation line, and the first sub-evacuation line corresponding to the processing container. The inside is set to the vacuum cleaning pressure,
The substrate processing apparatus according to claim 7.
further comprising a purge gas supply unit that supplies purge gas to the processing container,
The control unit supplies purge gas to the processing container from a gas supply unit provided separately from the processing fluid supply unit, in order to return the inside of the processing container to normal pressure after the vacuum cleaning process is completed. Item 1. Substrate processing apparatus according to item 1.
The substrate processing apparatus according to claim 9, wherein the purge gas is nitrogen gas.
The control unit according to claim 1, wherein the control unit causes the processing fluid supply unit to supply the processing fluid to the processing container in order to return the inside of the processing container to normal pressure after the vacuum cleaning process is completed. Substrate processing equipment.
A substrate processing apparatus comprising a processing container capable of accommodating a substrate, and a processing fluid supply unit supplying a processing fluid in a supercritical state to the processing container in order to perform supercritical drying processing on the substrate. In a cleaning method for cleaning the inside of a container,
When no substrate is housed in the processing container, the processing container is sealed and no fluid flows into the processing container, and in this state, the processing container is evacuated to perform the processing. A cleaning method that reduces the pressure inside a container to a predetermined vacuum cleaning pressure, vaporizes contaminants in the processing container, and discharges the contaminants from the processing container.
The processing container is evacuated using a first exhaust device and a second exhaust device,
The first exhaust device performs rough evacuation to reduce the pressure within the processing container from normal pressure to a pressure at which the second exhaust device can operate,
13. The cleaning method according to claim 12, wherein the second exhaust device then reduces the pressure within the processing vessel to the vacuum cleaning pressure.
The cleaning method according to claim 12, wherein the cleaning method is performed while heating the processing container with a heater.