JP6922048B2 - Substrate processing equipment, substrate processing method and recording medium - Google Patents

Description

The present invention relates to a technique for drying a substrate to which a liquid is attached using a processing fluid in a supercritical state.

In the manufacturing process of a semiconductor device for forming a laminated structure of integrated circuits on the surface of a substrate such as a semiconductor wafer (hereinafter referred to as a wafer), liquid treatment 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 a liquid or the like adhering to the surface of a wafer by such a liquid treatment (see, for example, Patent Document 1).

In the above drying method, when a fine and high aspect ratio pattern is formed on the surface of the substrate, the liquid in the recess of the pattern is in the recess of the pattern before being replaced by the processing fluid in the supercritical state. As the liquid evaporates, the pattern collapses. It is desired to establish a technique for more surely avoiding such an event.

Japanese Unexamined Patent Publication No. 2013-12538

An object of the present invention is to provide a technique for preventing the liquid in the recess of the pattern from evaporating before being replaced by the supercritical processing fluid.

According to one embodiment of the present invention, it is a substrate processing apparatus that dries a substrate on which a liquid adheres to a surface using a processing fluid in a supercritical state, and the surface is subjected to a processing container and the surface in the processing container. A substrate holding portion that faces upward and holds the substrate horizontally, a first fluid supply portion that is provided below the substrate held by the substrate holding portion and supplies a pressurized processing fluid, and the substrate holding portion. A second fluid supply unit that supplies the pressurized processing fluid, a fluid discharge unit that discharges the processing fluid from the processing container, and the first fluid supply unit, which are provided on the side of the substrate held by the above. A substrate processing apparatus including the second fluid supply unit and a control unit that controls the operation of the fluid discharge unit is provided. The control unit supplies the substrate processing apparatus with a pressurized processing fluid after accommodating the substrate having a liquid adhering to the surface in the processing container, and supplies the processed fluid pressurized in the processing container to the inside of the processing container. After the step of increasing the pressure to a processing pressure higher than the critical pressure of the processing fluid and the step of increasing the pressure, the processing container is charged with at least the pressure at which the processing fluid maintains a supercritical state in the processing container. A distribution step of supplying the processing fluid and discharging the processing fluid from the processing container is carried out. In the boosting step, the control unit stops the supply of the processing fluid from the second fluid supply unit until at least the pressure in the processing container reaches the critical pressure of the processing fluid, and the first control unit stops the supply of the processing fluid. The processing fluid is supplied from the fluid supply unit into the processing container, and the processing fluid is supplied from the second fluid supply unit into the processing container in the flow process.

According to another embodiment of the present invention, the processing container is pressurized after the accommodating step of accommodating the substrate in which the pattern is formed on the surface and the liquid is adhered to the surface in the processing container, and the accommodating step. After the step of increasing the pressure in the processing container to a processing pressure higher than the critical pressure of the processing fluid and the step of increasing the pressure, at least the processing fluid is generated in the processing container. The processing vessel is provided with a distribution step of supplying the pressurized processing fluid to the processing container and discharging the processing fluid from the processing container while maintaining a pressure for maintaining a supercritical state, and at least in the pressure increasing step. Until the pressure in the processing container reaches the critical pressure of the processing fluid, the pressurized processing fluid is supplied from the first fluid supply unit provided below the substrate, and in the distribution process, the substrate is supplied. A pressurized processing fluid is supplied from a second fluid supply unit provided on the side of the above, and in the pressurizing step, at least until the pressure in the processing container reaches the critical pressure of the processing fluid. A substrate processing method is provided in which the pressurized processing fluid is not supplied from the second fluid supply unit.

According to still another embodiment of the present invention, when executed by a computer for controlling the operation of the substrate processing apparatus, the computer controls the substrate processing apparatus to execute the above-mentioned substrate processing method. A storage medium on which is recorded is provided.

According to the above embodiment of the present invention, it is possible to prevent the liquid in the recess of the pattern from evaporating before being replaced by the processing fluid in the supercritical state.

It is a cross-sectional plan view which shows the whole structure of a substrate processing system. It is external perspective view of the processing container of a supercritical processing apparatus. It is sectional drawing of the processing container. It is a piping system diagram of a supercritical processing apparatus. It is a figure explaining the drying mechanism of IPA. It is a graph which shows the fluctuation of the pressure in the processing container during a drying process. It is a graph which shows the relationship between _{a CO 2} concentration, a critical temperature and a critical pressure in a mixed fluid composed of IPA and CO _2.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. It should be noted that the configuration shown in the drawings attached to the present specification may include parts in which the size, scale, etc. are changed from those of the actual product for the convenience of illustration and comprehension.

[Configuration of board processing system]
As shown in FIG. 1, the substrate processing system 1 includes a plurality of cleaning devices 2 (two cleaning devices 2 in the example shown in FIG. 1) that supply cleaning liquid to the wafer W to perform cleaning processing, and after cleaning processing. A plurality of supercritical fluids adhering to the wafer W for preventing drying (IPA: isopropyl alcohol in this embodiment) are removed by contacting with _{a processing fluid in a supercritical state (CO 2: carbon dioxide in this embodiment).} It includes a critical processing device 3 (six supercritical processing devices 3 in the example shown in FIG. 1).

In this substrate processing system 1, the FOUP 100 is mounted on the mounting unit 11, and the wafer W stored in the FOUP 100 is transferred to the cleaning processing unit 14 and the supercritical processing unit 15 via the loading / unloading unit 12 and the delivery unit 13. Delivered. In the cleaning processing unit 14 and the supercritical processing unit 15, the wafer W is first carried into the cleaning device 2 provided in the cleaning processing unit 14 to undergo the cleaning treatment, and then the supercritical processing unit 15 is provided. It is carried into the processing device 3 and undergoes a drying process for removing the IPA from the wafer W. In FIG. 1, the code "121" indicates a first transport mechanism for transporting the wafer W between the FOUP 100 and the transfer unit 13, and the code "131" indicates a loading / unloading unit 12, a cleaning processing unit 14, and a supercritical processing unit. The delivery shelf which serves as a buffer in which the wafer W transferred to and from 15 is temporarily placed is shown.

A wafer transfer path 162 is connected to the opening of the transfer section 13, and a cleaning process section 14 and a supercritical process section 15 are provided along the wafer transfer path 162. In the cleaning processing unit 14, one cleaning device 2 is arranged so as to sandwich the wafer transfer path 162, and a total of two cleaning devices 2 are installed. On the other hand, in the supercritical processing unit 15, three supercritical processing devices 3 functioning as substrate processing devices for performing a drying process for removing IPA from the wafer W are arranged with the wafer transfer path 162 in between, for a total of three. Six supercritical processing devices 3 are installed. A second transfer mechanism 161 is arranged in the wafer transfer path 162, and the second transfer mechanism 161 is provided so as to be movable in the wafer transfer path 162. The wafer W placed on the delivery shelf 131 is received by the second transfer mechanism 161 and the second transfer mechanism 161 carries the wafer W into the cleaning device 2 and the supercritical processing device 3. The number and arrangement of the cleaning device 2 and the supercritical processing device 3 are not particularly limited, and depend on the number of wafers W processed per unit time, the processing time of each cleaning device 2 and each supercritical processing device 3, and the like. , An appropriate number of cleaning devices 2 and supercritical processing devices 3 are arranged in an appropriate manner.

The cleaning device 2 is configured as a single-wafer type device that cleans the wafers W one by one by, for example, spin cleaning. In this case, while the wafer W is held horizontally and rotated around the vertical axis, the chemical solution for cleaning and the rinse solution for washing away the chemical solution are supplied to the processing surface of the wafer W at an appropriate timing. The wafer W can be washed. The chemical solution and rinsing solution used in the cleaning device 2 are not particularly limited. For example, the SC1 solution (that is, a mixed solution of ammonia and hydrogen peroxide solution), which is an alkaline chemical solution, can be supplied to the wafer W to remove particles and organic contaminants from the wafer W. After that, deionized water (DIW: DeIonized Water) which is a rinsing liquid can be supplied to the wafer W, and the SC1 liquid can be washed away from the wafer W. Further, a diluted hydrofluoric acid (DHF), which is an acidic chemical solution, is supplied to the wafer W to remove the natural oxide film, and then DIW is supplied to the wafer W to supply the diluted hydrofluoric acid aqueous solution from the wafer W. It can also be washed away.

Then, after the rinsing treatment by the DIW is completed, the cleaning apparatus 2 supplies the IPA as a liquid for preventing drying to the wafer W while rotating the wafer W, and replaces the DIW remaining on the processed surface of the wafer W with the IPA. After that, the rotation of the wafer W is gently stopped. At this time, a sufficient amount of IPA is supplied to the wafer W, the surface of the wafer W on which the semiconductor pattern is formed is in a state of being filled with IPA, and a liquid film of IPA is formed on the surface of the wafer W. .. The wafer W is carried out from the cleaning device 2 by the second transfer mechanism 161 while maintaining the state in which the IPA is filled with liquid.

The IPA thus applied to the surface of the wafer W plays a role of preventing the wafer W from drying. In particular, in order to prevent the so-called pattern collapse of the wafer W due to the evaporation of the IPA during the transfer of the wafer W from the cleaning device 2 to the supercritical processing device 3, the cleaning device 2 has a relatively large thickness of the IPA. A sufficient amount of IPA is applied to the wafer W so that the film is formed on the surface of the wafer W.

The wafer W carried out from the cleaning device 2 is carried into the processing container of the supercritical processing device 3 in a state where the IPA is filled with liquid by the second transport mechanism 161 and the IPA is dried in the supercritical processing device 3. Is done.

[Supercritical processing equipment]

Hereinafter, the supercritical processing apparatus 3 will be described with reference to FIGS. 2 to 4.

As shown in FIGS. 2 and 3, the processing container 301 includes a container body 311 in which an opening 312 for loading and unloading the wafer W is formed, a holding plate 316 for horizontally holding the wafer W to be processed, and the same. It is provided with a lid member 315 that supports the holding plate 316 and seals the opening 312 when the wafer W is carried into the container body 311.

The container body 311 is a container in which, for example, a processing space capable of accommodating a wafer W having a diameter of 300 mm is formed. A fluid supply header (second fluid supply unit) 317 is provided on one end side inside the container body 311 and a fluid discharge header (fluid discharge unit) 318 is provided on the other end side. In the illustrated example, the fluid supply header 317 is composed of a block body provided with a large number of openings (second fluid supply port), and the fluid discharge header 318 is composed of a pipe provided with a large number of openings (fluid discharge port). The second fluid supply port of the fluid supply header 317 is preferably located at a position slightly higher than the upper surface of the wafer W held by the holding plate 316.

The configuration of the fluid supply header 317 and the fluid discharge header 318 is not limited to the illustrated example, and for example, the fluid discharge header 318 may be formed from a block body, or the fluid supply header 317 may be formed from a pipe.

When the holding plate 316 is viewed from below, the holding plate 316 covers almost the entire lower surface of the wafer W. The holding plate 316 has an opening 316a at the end on the lid member 315 side. The processing fluid in the space above the holding plate 316 is guided through the opening 316a to the fluid discharge header 318 (see arrow F5 in FIG. 3).

The fluid supply header 317 supplies the processing fluid into the container body 311 (processing container 301) in a substantially horizontal direction. The horizontal direction referred to here is a direction perpendicular to the vertical direction on which gravity acts, and is usually a direction parallel to the direction in which the flat surface of the wafer W held by the holding plate 316 extends.

The fluid in the processing container 301 is discharged to the outside of the processing container 301 through the fluid discharge header 318. The fluid discharged via the fluid discharge header 318 includes the processing fluid supplied into the processing container 301 via the fluid supply header 317, as well as the IPA adhering to the surface of the wafer W and dissolved in the processing fluid. Is also included.

A fluid supply nozzle (first fluid supply unit) 341 for supplying the processing fluid to the inside of the processing container 301 is provided at the bottom of the container body 311. In the illustrated example, the fluid supply nozzle 341 comprises an opening drilled in the bottom wall of the container body 311. The fluid supply nozzle 341 is located below the center of the wafer W (for example, directly below), and supplies the processing fluid into the processing container 301 toward the center of the wafer W (for example, above in the vertical direction).

The processing container 301 further includes a pressing mechanism (not shown). This pressing mechanism plays a role of sealing the processing space by pressing the lid member 315 toward the container body 311 against the internal pressure generated by the processing fluid in the supercritical state supplied into the processing space. Further, it is preferable to provide a heat insulating material, a tape heater, or the like (not shown) on the ceiling wall and the bottom wall of the container body 311 so that the processing fluid supplied into the processing space can maintain the temperature in the supercritical state.

As shown in FIG. 4, the supercritical processing apparatus 3 has a fluid supply tank 51 which is a supply source of a processing fluid in a supercritical state, for example, a high-pressure processing fluid of about 16 to 20 MPa (megapascal). A main supply line 50 is connected to the fluid supply tank 51. The main supply line 50 is connected to the second supply line 63 connected to the fluid supply header (second fluid supply unit) 317 in the processing container 301 and the fluid supply nozzle ( first fluid supply unit) 341 on the way. It branches to the first supply line 64.

Between the fluid supply tank 51 and the fluid supply header 317 (that is, the main supply line 50 and the second supply line 63 connected to the main supply line 50), an on-off valve 52a, an orifice 55a, a filter 57 and an on-off valve 52b are provided from the upstream side. It is provided in order. The first supply line 64 branches from the main supply line 50 at a position between the filter 57 and the on-off valve 52b. The first supply line 64 is provided with an on-off valve 52c.

The orifice 55a is provided to reduce the flow velocity of the processing fluid supplied from the fluid supply tank 51 in order to protect the wafer W. The filter 57 is provided to remove foreign substances (particle-causing substances) contained in the processing fluid flowing through the main supply line 50.

The supercritical processing device 3 further enters the external space of the supercritical processing device 3 via the purge gas supply line 70 connected to the purge device 62 via the on-off valve 52d and the check valve 58a, and the on-off valve 52e and the orifice 55c. It has a connected discharge line 71. The purge gas supply line 70 and the discharge line 71 are connected to the main supply line 50, the second supply line 63, and the first supply line 64.

The purge gas supply line 70 is used, for example, for the purpose of filling the processing container 301 with an inert gas to maintain a clean state while the supply of the processing fluid from the fluid supply tank 51 to the processing container 301 is stopped. The discharge line 71 is used to discharge the processing fluid remaining in the supply line between the on-off valve 52a and the on-off valve 52b to the outside when the power of the supercritical processing device 3 is turned off, for example.

A main discharge line 65 is connected to the fluid discharge header 318 in the processing container 301. The main discharge line 65 branches into a first discharge line 66, a second discharge line 67, a third discharge line 68, and a fourth discharge line 69 on the way.

An on-off valve 52f, a back pressure valve 59, a concentration sensor 60, and an on-off valve 52g are provided in order from the upstream side in the main discharge line 65 and the first discharge line 66 connected to the main discharge line 65.

The back pressure valve 59 opens when the primary side pressure (which is equal to the pressure in the processing vessel 301) exceeds the set pressure, and keeps the primary side pressure at the set pressure by flowing a fluid to the secondary side. It is configured to do. The set pressure of the back pressure valve 59 can be changed at any time by the control unit 4.

The concentration sensor 60 is a sensor that measures the IPA concentration of the fluid flowing through the main discharge line 65.

On the downstream side of the on-off valve 52g, the first discharge line 66 is provided with a needle valve (variable throttle) 61a and a check valve 58b. The needle valve 61a is a valve that adjusts the flow rate of the fluid discharged to the outside of the supercritical processing device 3 through the first discharge line 66.

It branches from the main discharge line 65 at a position between the second discharge line 67, the third discharge line 68 and the fourth discharge line 69, the concentration sensor 60 and the on-off valve 52 g. The second discharge line 67 is provided with an on-off valve 52h, a needle valve 61b, and a check valve 58c. The third discharge line 68 is provided with an on-off valve 52i and a check valve 58d. The fourth discharge line 69 is provided with an on-off valve 52j and an orifice 55d.

The second discharge line 67 and the third discharge line 68 are connected to a first discharge destination such as a fluid recovery device, and the fourth discharge line 69 is a second discharge destination such as an air space or a factory outside the supercritical processing device 3. It is connected to the exhaust system.

When the fluid is discharged from the processing container 301, one or more of the on-off valves 52g, 52h, 52i, and 52j are opened. In particular, when the supercritical processing device 3 is stopped, the on-off valve 52j is opened to discharge the fluid existing in the first discharge line 66 between the concentration sensor 60, the concentration sensor 60 and the on-off valve 52g to the outside of the supercritical processing device 3. You may.

Pressure sensors for detecting the pressure of the fluid and temperature sensors for detecting the temperature of the fluid are installed at various locations on the line through which the fluid of the supercritical processing apparatus 3 flows. In the example shown in FIG. 4, a pressure sensor 53a and a temperature sensor 54a are provided between the on-off valve 52a and the orifice 55a, and a pressure sensor 53b and a temperature sensor 54b are provided between the orifice 55a and the filter 57. A pressure sensor 53c is provided between the on-off valve 52b, a temperature sensor 54c is provided between the on-off valve 52b and the processing container 301, and a temperature sensor 54d is provided between the orifice 55b and the processing container 301. .. Further, a pressure sensor 53d and a temperature sensor 54f are provided between the processing container 301 and the on-off valve 52f, and a pressure sensor 53e and a temperature sensor 54g are provided between the concentration sensor 60 and the on-off valve 52g. Further, a temperature sensor 54e for detecting the temperature of the fluid in the processing container 301 is provided.

The main supply line 50 and the second supply line 63 are provided with four heaters H for adjusting the temperature of the processing fluid supplied to the processing container 301. A heater H may also be provided on the discharge line on the downstream side of the processing container 301.

A safety valve (relief valve) 56a is provided between the orifice 55a of the main supply line 50 and the filter 57, a safety valve 56b is provided between the processing container 301 and the on-off valve 52f, and the concentration sensor 60 and the on-off valve 52g are provided. A safety valve 56c is provided between them. These safety valves 56a to 56c urgently discharge the fluid in the line to the outside in the event of an abnormality such as when the pressure in the line (piping) provided with these safety valves becomes excessive.

The control unit 4 receives measurement signals from various sensors (pressure sensors 53a to 53e, temperature sensors 54a to 54g, concentration sensor 60, etc.) shown in FIG. 3, and controls various functional elements (opening and closing of on-off valves 52a to 52j). A signal, a set pressure adjustment signal of the back pressure valve 59, an opening degree adjustment signal of the needle valves 61a to 61b, etc.) are transmitted. The control unit 4 is, for example, a computer, and includes a calculation unit 18 and a storage unit 19. The storage unit 19 stores programs that control various processes executed in the substrate processing system 1. The arithmetic unit 18 controls the operation of the substrate processing system 1 by reading and executing the program stored in the storage unit 19. The program may be recorded on a storage medium readable by a computer, and may be installed from the storage medium in the storage unit 19 of the control unit 4. Examples of storage media that can be read by a computer include a hard disk (HD), a flexible disk (FD), a compact disk (CD), a magnet optical disk (MO), and a memory card.

[Supercritical drying treatment]
Next, the drying mechanism of IPA using a processing fluid in a supercritical state (for example, carbon dioxide (CO ₂ )) will be briefly described with reference to FIG.

Immediately after the processing fluid R in the supercritical state is introduced into the processing container 301, only IPA exists in the recess of the pattern P of the wafer W as shown in FIG. 5 (a).

The IPA in the recess gradually dissolves in the processing fluid R by coming into contact with the processing fluid R in the supercritical state, and gradually replaces the processing fluid R as shown in FIG. 5 (b). At this time, in addition to the IPA and the processing fluid R, a mixed fluid M in a state in which the IPA and the processing fluid R are mixed exists in the recess.

As the replacement of IPA with the processing fluid R progresses in the recess, the IPA existing in the recess decreases, and finally, as shown in FIG. 5C, the processing fluid in the supercritical state is contained in the recess. Only R will exist.

After the IPA is removed from the recess, the pressure in the processing container 301 is lowered to atmospheric pressure, so that the processing fluid R changes from the supercritical state to the gaseous state as shown in FIG. 5 (d), and the inside of the recess is changed. Is occupied only by gas. In this way, the IPA in the recess of the pattern P is removed, and the drying process of the wafer W is completed.

Next, a drying method (board processing method) executed by using the above supercritical processing apparatus 3 will be described. The drying method described below is automatically executed under the control of the control unit 4 based on the processing recipe and the control program stored in the storage unit 19.

<Carry-in process>
The wafer W that has been cleaned in the cleaning device 2 is filled with the IPA in the recesses of the pattern on the surface thereof, and the paddle of the IPA is formed on the surface of the wafer W. Is carried out from. In the second transfer mechanism 161, the wafer is placed on the holding plate 316, after that, the holding plate 316 on which the wafer is placed enters the container body 311 and the lid member 315 is hermetically engaged with the container body 311. do. This completes the loading of the wafer.

Next, according to the procedure shown in the time chart of FIG. 6, the processing fluid (CO ₂ ) is supplied into the processing container 301, whereby the wafer W is dried. The polygonal line A shown in FIG. 6 shows the relationship between the elapsed time from the start of the drying process and the pressure in the processing container 301.

<Pressurization process>
First, the boosting step T1 is performed, and CO ₂ (carbon dioxide) as a processing fluid is supplied from the fluid supply tank 51 into the processing container 301. Specifically, the on-off valves 52a, 52c, 52f are set to the open state, and the on-off valves 52b, 52d, and the on-off valve 52e are set to the closed state. Further, the on-off valves 52g, 52h, 52i are opened, and the on-off valves 52j are closed. The needle valves 61a and 61b are adjusted to a predetermined opening degree. Further, the set pressure of the back pressure valve 59 is set to a pressure at which CO ₂ in the processing container 301 can maintain a supercritical state, for example, 15 MPa. _{As a result, CO 2} having a pressure of about 16 MPa in a supercritical state is discharged from the fluid supply tank 51 from the fluid supply nozzle 341 directly below the central portion of the wafer W toward the lower surface of the holding plate 316.

_{CO 2} discharged from the fluid supply nozzle 341 (see arrow F1 in FIG. 3) collides with the holding plate 316 covering the lower surface of the wafer W and then spreads radially along the lower surface of the holding plate 316 (arrow in FIG. 3). (See F2), and then flows into the space on the upper surface side of the wafer W through the gap between the edge of the holding plate 316 and the side wall of the container body 311 and the opening 316a of the holding plate 316 (arrow F3 in FIG. 3). reference). Since the back pressure valve 59 is kept fully closed up to the set pressure (15 MPa), CO ₂ does not flow out from the processing container 301. Therefore, the pressure in the processing container 301 gradually increases.

_{In the initial stage of the pressurizing step T1, the pressure of CO 2} sent out from the fluid supply tank 51 in the supercritical state decreases when passing through the orifice 55a, and when it flows into the processing container 301 in the normal pressure state. Also drops. Therefore, in the initial stage of the pressurizing step T1, _{the pressure of CO 2} flowing into the processing container 301 is lower than the critical pressure (for example, about 7 MPa), that is, CO ₂ flows into the processing container 301 in a gas state. .. After that, _{the pressure in the processing container 301 increases as the filling of CO 2} into the processing container 301 progresses, and when the pressure in the processing container 301 exceeds the critical pressure, the CO ₂ existing in the processing container 301 is released. It becomes a supercritical state.

In the pressurizing step T1, when the pressure in the processing container 301 increases and exceeds the critical pressure, the processing fluid in the processing container 301 becomes a supercritical state, and the IPA on the wafer W begins to dissolve in the processing fluid in the supercritical state. Then, the mixing ratio _{of IPA and CO 2} in the mixed fluid composed of _{CO 2 and IPA changes.} The mixing ratio is not always uniform over the entire surface of the wafer W. To prevent pattern collapse due to vaporization of accidental mixing fluids, step-up step T1, the pressure in the processing container 301, the CO ₂ in the processing chamber 301 regardless of the CO ₂ concentration in the mixed fluid reaches a supercritical state Guaranteed pressure Here, the pressure is increased to 15 MPa. Here, the "pressure guaranteed to be in a supercritical state" is a pressure higher than the maximum value of the pressure shown by the curve C in the graph of FIG. 7. This pressure (15 MPa) is called the "processing pressure".

<Holding process>
When the pressure in the processing container 301 rises to the processing pressure (15 MPa) by the pressure increasing step T1, the on-off valve 52b and the on-off valve 52f located on the upstream side and the downstream side of the processing container 301 are closed, respectively, and the processing container 301 is closed. The process proceeds to the holding step T2 for maintaining the pressure inside. _{In this holding step, the IPA concentration and the CO 2} concentration in the mixed fluid in the recess of the pattern P of the wafer W become predetermined concentrations (for example, the IPA concentration is 30% or less and the CO ₂ concentration is 70% or more). Will continue until. The time of the holding step T2 can be determined experimentally. In this holding step T2, the open / closed state of the other valves is the same as the open / closed state in the boosting step T1.

<Distribution process>
After the holding step T2, the distribution step T3 is performed. The distribution process T3 is a step of lowering the pressure in the processing container 301 by discharging a mixed fluid of _{CO 2 and IPA from the processing container 301, and a new CO 2 containing no IPA in the processing container 301 from the fluid supply tank 51.} This can be performed by alternately repeating the step of supplying and boosting the pressure inside the processing container 301.

The distribution step T3 is performed, for example, by repeatedly increasing and decreasing the set pressure of the back pressure valve 59 with the on-off valve 52b and the on-off valve 52f in the open state. Instead of this, the distribution step T3 may be performed by repeatedly opening and closing the on-off valve 52f with the on-off valve 52b opened and the set pressure of the back pressure valve 59 set to a low value.

_{In the distribution process T3, CO 2} is supplied into the processing container 301 using the fluid supply header 317 (see arrow F4 in FIG. 3). The fluid supply header 317 can supply _{CO 2} at a larger flow rate than the fluid supply nozzle 341. In the distribution process T3, the pressure inside the processing container 301 is maintained at a pressure sufficiently higher than the critical pressure, so that even if a large flow rate of CO ₂ collides with the wafer W surface or flows near the wafer W surface, it dries. There is no problem. Therefore, the fluid supply header 317 is used with an emphasis on shortening the processing time.

In the step of increasing the pressure, the pressure in the processing container 301 is increased to the above processing pressure (15 MPa). In the step of lowering the pressure, the pressure in the processing container 301 is reduced from the above processing pressure to a predetermined pressure (pressure higher than the critical pressure). In the step down step, the processing fluid is supplied into the processing container 301 via the fluid supply header 317, and the processing fluid is exhausted from the processing container 301 through the fluid discharge header 318. Therefore, the processing fluid is discharged into the processing container 301. Is formed with a laminar flow of the processing fluid flowing substantially parallel to the surface of the wafer W (see arrow F6 in FIG. 3).

By performing the distribution process, the substitution _{of IPA with CO 2} is promoted in the recess of the pattern of the wafer W. As the substitution of IPA to CO ₂ progresses in the recess, the critical pressure of the mixed fluid decreases as shown on the left side of FIG. 7, so that the pressure in the processing container 301 at the end of each step-down step is reached. Can be gradually lowered while satisfying the condition that the pressure is higher than the critical pressure of the mixed fluid corresponding to the CO _{2 concentration in the mixed fluid.}

<Discharge process>
_{When the replacement of IPA with CO 2} is completed in the recess of the pattern by the distribution step T3, the discharge step T4 is performed. In the discharge step T4, the on-off valves 52a, 52b, 52c, 52d, 52e are closed, the set pressure of the back pressure valve 59 is set to normal pressure, the on-off valves 52f, 52g, 52h, 52i are opened, and the on-off valve 52j is opened. This can be done by closing the state. When the pressure in the processing chamber 301 by the discharge step T4 is lower than the critical pressure of CO _2, CO ₂ in the supercritical state is vaporized, separates from the recess pattern. As a result, the drying process for one wafer W is completed.

According to the above embodiment, in the boosting step T1, CO ₂ is supplied into the processing container 301 from the fluid supply nozzle 341 below the wafer W. Therefore, the collapse of the pattern can be prevented more reliably. This point will be described below.

When the liquid IPA existing on the surface of the wafer W _{is exposed to the flow of CO 2 in} the gaseous state, the IPA evaporates, and at this time, the pattern may collapse. _{In the boosting step T1, when the gaseous CO 2} is supplied into the processing container 301 from the fluid supply header 317 on the side of the wafer W, the _{flow of CO 2} having a relatively high flow velocity directly collides with the paddle of the IPA. Or, because it passes near the paddle of IPA, evaporation of IPA tends to occur easily.

On the other hand, in the present embodiment, the CO ₂ discharged from the fluid supply nozzle 341 does not flow directly toward the surface of the wafer W or the space near the surface, but collides with the central portion of the lower surface of the holding plate 316. Later, it spreads radially along the lower surface of the holding plate 316 and then flows into the space on the upper surface side of the wafer W. That is, in the present embodiment, there is no _{CO 2} flow directly from the processing fluid discharge port to the surface of the wafer W or the space near the surface. Therefore, the evaporation of IPA caused by supplying the _{gaseous CO 2} into the processing container 301 is significantly suppressed. When the gaseous CO ₂ flows into the space on the upper surface side of the wafer W, _{the flow velocity of the CO 2} is significantly smaller than that when it is discharged from the fluid supply nozzle 341. Further, since the first supply line has the orifice 55b, the flow velocity of _{CO 2} discharged from the fluid supply nozzle 341 is originally small. This further suppresses the evaporation of IPA.

In the above embodiment, the position of the fluid supply nozzle 341 is, for example, directly below the central portion of the wafer W housed in the processing container 301, but the position is not limited to this. The position of the fluid supply nozzle 341 may be a position below the holding plate 316, that is, a position where the fluid supply nozzle 341 cannot be seen when the holding plate 316 on which the wafer W is placed is viewed from directly above. In other words, the CO ₂ gas discharged from the fluid supply nozzle 341 may collide with the lower surface of the fluid supply nozzle 341 or the back surface (lower surface) of the wafer W.

However, if the position of the fluid supply nozzle 341 is large and deviates from directly below the center of the wafer W, _{the flow of CO 2} gas in the processing container 301 becomes non-uniform, and _{the flow of CO 2} gas may wrap around the surface of the wafer W. There is. Therefore, it is desirable that the fluid supply nozzle 341 is arranged at a position close to directly below the center of the wafer W. Further, _{from the viewpoint of preventing or suppressing the flow of CO 2} gas from wrapping around the surface of the wafer W, it is desirable that _{the fluid supply nozzle 341 discharges CO 2 in the vertical direction upward or substantially in the vertical direction upward.}

_{In the above embodiment, CO 2} is supplied into the processing container 301 only from the fluid supply nozzle 341 for the entire period of the boosting step T1, but the present invention is not limited to this. Once beyond the pressure of the processing chamber 301 is a processing fluid CO ₂ the critical pressure (about 7 MPa), may be supplied from a fluid supply header 317 of CO ₂ into the processing vessel 301, The fluid supply header 317 and a fluid _{CO 2} may be supplied into the processing container 301 from both of the supply nozzles 341. In these cases as well, it is possible to prevent the pattern from collapsing.

However, as in the above embodiment, it is preferable to supply _{CO 2} into the processing container 301 only from the fluid supply nozzle 341 over the entire period of the boosting step T1. _{When CO 2} is supplied into the processing container 301 from the fluid supply header 317 _{, the supplied CO 2} directly collides with the paddle made of IPA or _{a mixed fluid of IPA and CO 2} to agitate the paddle, so that particles are likely to be generated. This is because it tends to be. In addition, it is possible to prevent the pattern from collapsing more reliably.

_{When an actual test was conducted, when CO 2} was supplied into the processing container 301 from only the fluid supply nozzle 341 over the entire period of the boosting step T1, the pattern collapse could be prevented and the generation of particles was not a problem. Met. _{On the other hand, when CO 2 is supplied from the fluid supply header 317 and CO 2} from both the fluid supply header 317 and the fluid supply nozzle 341 in the latter half of the pressurization step T1 (after the pressure inside the processing container 301 exceeds about 7 MPa). In the case of supplying, the collapse of the pattern could be prevented, but the particle level deteriorated.

However, since the boosting speed can be increased by using the fluid supply header 317 as compared with the case of using the fluid supply nozzle 341, depending on the required particle level, the throughput is emphasized and the latter half of the boosting step T1 is emphasized. _{CO 2} may be supplied into the processing container 301 by using the fluid supply header 317.

The present invention is not limited to the above-described embodiments and modifications, but may include various aspects to which various modifications that can be conceived by those skilled in the art are added, and the effects produced by the present invention are also described above. It is not limited to the matters of. Therefore, various additions, changes, and partial deletions can be made to the scope of claims and each element described in the specification without departing from the technical idea and purpose of the present invention.

For example, the processing fluid used for the drying treatment may be _{a fluid other than CO 2} (for example, a fluorine-based fluid), and any fluid capable of removing the anti-drying liquid filled on the substrate in a supercritical state. Can be used as the processing fluid. Further, the anti-drying liquid is not limited to IPA, and any liquid that can be used as the anti-drying liquid can be used. The substrate to be processed is not limited to the above-mentioned semiconductor wafer W, and may be another substrate such as a glass substrate for LCD or a ceramic substrate.

W substrate (wafer)
4 Control unit 316 Board holding part (holding plate)
317 Second fluid supply section (fluid supply header)
341 First fluid supply unit (fluid supply nozzle)

Claims (15)

A substrate processing device that dries a single substrate with a liquid attached to its surface using a processing fluid in a supercritical state.
Processing container and
A holding plate that holds the substrate horizontally in the processing container with the surface facing upward on the upper surface side thereof , and the holding plate that holds the substrate in the processing container allows the processing container to be held. interior space, said holding plate provided so as to be divided into two spaces with lower space below the holding plate which communicates with the upper space and the upper space above the holding plate, wherein the substrate is present ,
It is provided below the holding plate that holds the substrate in the processing container, and is pressed into the lower space from below the holding plate that holds the substrate in the processing container toward the holding plate. The first fluid supply unit that supplies the processing fluid and
The processing fluid provided on the side of the substrate held by the holding plate in the processing container and pressurized toward the substrate from the side of the substrate is supplied to the internal space of the processing container. 2 fluid supply unit and
A fluid discharge unit that discharges the processing fluid from the internal space of the processing container,
With
The holding plate can be moved while holding the substrate between the outside of the processing container and the inside of the processing container.
The processing fluid supplied from the first fluid supply unit to the lower space collides with the lower surface of the holding plate inside the processing container, spreads along the lower surface of the holding plate, and then enters the upper space. A substrate processing apparatus characterized in that it is designed to flow in. The first fluid supply unit, from the lower central portion of the substrate held by the holding plate, wherein the processing fluid toward the lower surface of the holding plate corresponding to the central portion of the substrate held by the holding plate The substrate processing apparatus according to claim 1, wherein the substrate processing apparatus is provided so as to supply the fluid. Said holding plate such that said said processing fluid discharged from the first fluid supply portion does not collide directly with the substrate held by the holding plate, the substrate held by the holding plate when viewed from below The substrate processing apparatus according to claim 1, which is provided so as to cover the entire lower surface of the substrate. Inside the processing container, there is a communication passage that communicates the upper space and the lower space outside the peripheral edge of the substrate held by the holding plate, and from the first fluid supply unit to the lower space. The substrate processing apparatus according to claim 1, wherein the supplied processing fluid can flow into the upper space through the communication passage. And the outer peripheral edge of the holding plate before Symbol substrate is placed thereon, the gap serving as the communication passage between an inner wall surface of the processing container is adapted to be formed, according to claim 4, wherein Substrate processing equipment. The substrate according to claim 1, wherein the second fluid supply unit is provided so as to supply the processing fluid in a substantially horizontal direction from the side of the substrate held by the holding plate in the processing container. Processing equipment. The second fluid supply unit is a side surface of the substrate held by the holding plate in the processing container, and the processing fluid is fed parallel to the surface of the substrate from a position higher than the upper surface of the substrate. The substrate processing apparatus according to claim 6, which is provided to supply the fluid. The substrate processing apparatus according to claim 6 or 7, wherein the second fluid supply unit has a plurality of fluid supply ports. The substrate processing apparatus according to claim 8, wherein the plurality of fluid supply ports are at the same height position and at different horizontal positions. A main supply line extending downstream from the source of the pressurized processing fluid,
A first supply line and a second supply line that branch from the main supply line at a branch point set in the main supply line and supply the processing fluid to the first fluid supply unit and the second fluid supply unit, respectively. ,
The first on-off valve provided in the first supply line and
A second on-off valve provided in the second supply line and
A first orifice provided in the main supply line on the upstream side of the branch point,
The substrate processing apparatus according to any one of claims 1 to 9, further comprising. The substrate processing apparatus according to claim 10, further comprising a second orifice provided in the first supply line. The substrate processing apparatus according to claim 10 or 11, further comprising a heater and a filter provided in the main supply line on the upstream side of the branch point. The substrate processing apparatus according to claim 12, wherein the heater is provided on the upstream side of the first orifice, and the filter is provided on the downstream side of the first orifice. The main discharge line connected to the fluid discharge part and
A back pressure valve provided in the main discharge line and capable of changing the set pressure via a control unit,
The substrate processing apparatus according to any one of claims 1 to 13, further comprising the above. The main discharge line branches into a plurality of branch discharge lines on the downstream side of the back pressure valve and then merges again to form one discharge line, and each of the plurality of branch discharge lines is provided with an on-off valve. Item 14. The substrate processing apparatus according to item 14.

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