Substrate processing method

Abstract

To provide a substrate processing method which has excellent drying performance and satisfactorily dries a substrate having a pattern formed on the surface thereof.SOLUTION: A substrate processing method includes a liquid film forming step of supplying a processing liquid in which a sublimable substance is dissolved in a solvent to the surface of a substrate on which a pattern is formed to form a liquid film of the processing liquid on the surface of the substrate, a solidified film forming step of solidifying the liquid film of the processing liquid to form a solidified film of the sublimable substance, and a sublimation step of sublimating the solidified film and removing it from the surface of the substrate. In the liquid film forming step, the substrate is rotated around a rotation axis parallel to the normal to the surface of the substrate. The solidified film forming step includes a step of rotating the substrate around the rotation axis at a rotation speed lower than the rotation speed of the substrate in the liquid film forming step and filling the pattern with the sublimable substance.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a substrate processing method for processing substrates having patterns formed on their surfaces, including semiconductor wafers, substrates for liquid crystal displays, substrates for FPDs (Flat Panel Displays) such as organic electroluminescence (EL) displays, substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photomasks, ceramic substrates, and substrates for solar cells. [Background technology]

[0002] Manufacturing processes for electronic components such as semiconductor devices and liquid crystal display devices include a process of forming a pattern by repeatedly performing processes such as film formation and etching on the surface of a substrate. After forming this pattern, cleaning with a chemical solution, rinsing with a rinse solution, and drying are performed in this order. As patterns become finer, the importance of drying has become particularly important. In other words, techniques for suppressing or preventing pattern collapse during drying have become important. Therefore, as described in Patent Document 1, for example, a substrate processing method has been proposed in which a substrate is sublimated and dried using a processing solution in which camphor is dissolved in IPA (isopropyl alcohol). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-243869 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned conventional technology, camphor, a typical example of a sublimable substance, is used to improve the drying performance of the substrate. However, depending on the substrate processing conditions, it is not possible to prevent pattern collapse, and the conventional technology does not yet satisfy the drying performance required in the manufacturing sites of electronic components.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a substrate processing method that has excellent drying performance and can satisfactorily dry a substrate having a pattern formed on its surface. [Means for solving the problem]

[0006] A first aspect of the present invention is a substrate processing method, comprising: a liquid film forming step of supplying a processing liquid, in which a sublimable substance is dissolved in a solvent, to a surface of a substrate on which a pattern has been formed, to form a liquid film of the processing liquid on the surface of the substrate; a solidified film forming step of solidifying the liquid film of the processing liquid to form a solidified film of the sublimable substance; and a sublimation step of sublimating the solidified film and removing it from the surface of the substrate, wherein in the liquid film forming step, the substrate is rotated about a rotation axis parallel to a surface normal of the substrate, and in the solidified film forming step, the substrate is rotated about the rotation axis at a rotation speed lower than the rotation speed of the substrate in the liquid film forming step to form a solidified film of the sublimable substance. material After filling the pattern with the processing liquid, the process includes a step of increasing the rotation speed of the substrate while discharging an inert gas onto the surface of the substrate to promote solidification of the processing liquid film. A second aspect of the present invention is a substrate processing method comprising: a liquid film forming step of supplying a processing liquid, in which a sublimable substance is dissolved in a solvent, onto a surface of a substrate on which a pattern has been formed, to form a liquid film of the processing liquid on the surface of the substrate; a solidified film forming step of solidifying the liquid film of the processing liquid to form a solidified film of the sublimable substance; and a sublimation step of sublimating and removing the solidified film from the surface of the substrate, wherein in the liquid film forming step, the substrate is rotated about a rotation axis parallel to a surface normal of the substrate, and in the solidified film forming step, with the supply of the processing liquid stopped, the substrate is rotated about the rotation axis at a rotation speed equal to or higher than the rotation speed of the substrate in the liquid film forming step to spin off part of the processing liquid on the substrate, and then the substrate is rotated about the rotation axis at a rotation speed lower than the rotation speed of the substrate in the liquid film forming step to spin off the sublimable substance. material The method further comprises a step of discharging an inert gas onto the surface of the substrate while increasing the rotation speed of the substrate after filling the pattern with the inert gas. [Effects of the Invention]

[0007] The substrate can be dried well under various substrate processing conditions while preventing the pattern from collapsing. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a plan view showing a schematic configuration of a first embodiment of a substrate processing apparatus according to the present invention. [Figure 2] FIG. 2 is a side view of the substrate processing apparatus shown in FIG. [Figure 3] FIG. 2 is a partial cross-sectional view showing the configuration of a processing unit. [Figure 4] FIG. 2 is a block diagram showing the electrical configuration of a control unit that controls the processing unit. [Figure 5] FIG. 2 is a diagram showing a configuration of a processing liquid supply unit. [Figure 6] 1A to 1C are diagrams showing the contents of a substrate processing performed in a first embodiment of a substrate processing method according to the present invention. [Figure 7] 5A to 5C are diagrams showing the contents of a substrate processing performed in a second embodiment of a substrate processing method according to the present invention. [Figure 8] 10A to 10C are diagrams showing the contents of a substrate processing performed in a third embodiment of a substrate processing method according to the present invention. [Figure 9] 10 is a timing chart of substrate processing performed in a fourth embodiment of a substrate processing method according to the present invention. [Figure 10] 10A and 10B are diagrams summarizing verification results of the substrate processing method according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment <<Overall configuration of substrate processing equipment>> FIG. 1 is a plan view showing a schematic configuration of a first embodiment of a substrate processing apparatus according to the present invention. FIG. 2 is a side view of the substrate processing apparatus shown in FIG. 1. These drawings do not show the external appearance of the apparatus, but are schematic views clearly illustrating the internal structure of the substrate processing apparatus 100 by excluding the outer wall panel and other components. The substrate processing apparatus 100 is a single-wafer processing apparatus installed, for example, in a clean room, for processing substrates W, each of which has a circuit pattern or the like (hereinafter referred to as a "pattern") formed on only one main surface. A first embodiment of a substrate processing method according to the present invention is executed in the substrate processing apparatus 100. In this specification, a pattern-formed surface (one main surface) on which a pattern is formed is referred to as a "front surface Wf," and the opposite main surface on which no pattern is formed is referred to as a "back surface Wb." A surface facing downward is referred to as a "bottom surface," and a surface facing upward is referred to as a "top surface." In this specification, a "pattern-formed surface" refers to a surface of a substrate on which a concave-convex pattern is formed in any region, regardless of whether the surface is flat, curved, or concave-convex.

[0010] Here, the "substrate" in this embodiment can be any of various substrates such as semiconductor wafers, glass substrates for photomasks, glass substrates for liquid crystal displays, glass substrates for plasma displays, substrates for FEDs (Field Emission Displays), substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, etc. The following description will be given with reference to the drawings, taking as an example a substrate processing apparatus used primarily for processing semiconductor wafers, but the invention can also be applied to processing the various substrates exemplified above.

[0011] 1, the substrate processing apparatus 100 includes a substrate processing unit 110 that processes substrates W, and an indexer unit 120 coupled to the substrate processing unit 110. The indexer unit 120 includes a container holder 121 that can hold a plurality of containers C for accommodating substrates W (such as a FOUP (Front Opening Unified Pod), an SMIF (Standard Mechanical Interface) pod, or an OC (Open Cassette) that accommodates a plurality of substrates W in a sealed state), and an indexer robot 122 that accesses the containers C held by the container holder 121 to remove unprocessed substrates W from the container C or store processed substrates W in the container C. Each container C accommodates a plurality of substrates W in a substantially horizontal position.

[0012] The indexer robot 122 comprises a base 122a fixed to the apparatus housing, an articulated arm 122b rotatable about a vertical axis relative to the base 122a, and a hand 122c attached to the tip of the articulated arm 122b. The hand 122c is structured so that a substrate W can be placed on its upper surface and held thereon. Indexer robots having such articulated arms and hands for holding substrates are well known, and therefore a detailed description thereof will be omitted.

[0013] The substrate processing section 110 includes a substrate transfer robot 111 disposed approximately in the center in a plan view, and a plurality of processing units 1 disposed to surround the substrate transfer robot 111. Specifically, a plurality of processing units 1 (eight in this example) are disposed facing the space in which the substrate transfer robot 111 is disposed. The substrate transfer robot 111 randomly accesses these processing units 1 to hand over substrates W. Meanwhile, each processing unit 1 performs a predetermined process on the substrate W. In this embodiment, these processing units 1 have the same function. This enables parallel processing of multiple substrates W.

[0014] <<Configuration of Processing Unit 1>> Fig. 3 is a partial cross-sectional view showing the configuration of a processing unit. Fig. 4 is a block diagram showing the electrical configuration of a control unit that controls the processing units. In this embodiment, a control unit 4 is provided for each processing unit 1, but multiple processing units 1 may be controlled by one control unit. Alternatively, the processing units 1 may be controlled by a control unit (not shown) that controls the entire substrate processing apparatus 100.

[0015] The processing unit 1 includes a chamber 2 having an internal space 21 and a spin chuck 3 accommodated in the internal space 21 of the chamber 2 and holding a substrate W. As shown in FIGS. 1 and 2, a shutter 23 is provided on a side surface of the chamber 2. A shutter opening / closing mechanism 22 (FIG. 4) is connected to the shutter 23 and opens and closes the shutter 23 in response to an opening / closing command from the control unit 4. More specifically, in the processing unit 1, when an unprocessed substrate W is loaded into the chamber 2, the shutter opening / closing mechanism 22 opens the shutter 23, and the unprocessed substrate W is loaded face-up onto the spin chuck 3 by the hand of the substrate transfer robot 111. That is, the substrate W is placed on the spin chuck 3 with its front surface Wf facing upward. After the substrate W is loaded, when the hand of the substrate transfer robot 111 retreats from the chamber 2, the shutter opening / closing mechanism 22 closes the shutter 23. Then, as described below, chemical solutions, DIW (deionized water), an IPA processing liquid, and nitrogen gas are supplied to the surface Wf of the substrate W within the internal space 21 of the chamber 2, and the desired substrate processing is performed in a room temperature environment. After the substrate processing is completed, the shutter opening / closing mechanism 22 reopens the shutter 23, and the hand of the substrate transfer robot 111 removes the processed substrate W from the spin chuck 3. In this manner, in this embodiment, the internal space 21 of the chamber 2 functions as a processing space for performing substrate processing while maintaining a room temperature environment. In this specification, "room temperature" means a temperature range of 5°C to 35°C.

[0016] The spin chuck 3 includes a plurality of chuck pins 31 for gripping the substrate W, a spin base 32 formed in a disk shape extending horizontally and supporting the plurality of chuck pins 31, a central shaft 33 connected to the spin base 32 and rotatable about a rotation axis C1 parallel to a surface normal extending from the center of the surface of the substrate W, and a substrate rotation drive mechanism 34 that rotates the central shaft 33 about the rotation axis C1 using a motor. The plurality of chuck pins 31 are provided on the periphery of the upper surface of the spin base 32. In this embodiment, the chuck pins 31 are arranged at equal intervals in the circumferential direction. When the motor of the substrate rotation drive mechanism 34 is activated in response to a rotation command from the control unit 4 while the substrate W placed on the spin chuck 3 is gripped by the chuck pins 31, the substrate W rotates about the rotation axis C1. Furthermore, while the substrate W is being rotated in this manner, chemical liquid, IPA, DIW, processing liquid and nitrogen gas are sequentially supplied onto the surface Wf of the substrate W from nozzles provided in the atmosphere blocking mechanism 5 in response to a supply command from the control unit 4.

[0017] The atmosphere shutoff mechanism 5 includes a shutoff plate 51, an upper spin shaft 52 rotatably mounted on the shutoff plate 51, and a nozzle 53 vertically penetrating the center of the shutoff plate 51. The shutoff plate 51 is finished in a circular disk shape with a diameter substantially equal to or greater than that of the substrate W. The shutoff plate 51 is disposed opposite, with a gap therebetween, the upper surface of the substrate W held by the spin chuck 3. Therefore, the lower surface of the shutoff plate 51 functions as a circular substrate-facing surface 51a that faces the entire front surface Wf of the substrate W. Furthermore, a cylindrical through-hole 51b that vertically penetrates the shutoff plate 51 is formed in the center of the substrate-facing surface 51a.

[0018] The upper spin shaft 52 is rotatably provided about a rotation axis (coincident with the rotation axis C1 of the substrate W) that passes through the center of the shielding plate 51 and extends vertically. The upper spin shaft 52 has a cylindrical shape. The inner peripheral surface of the upper spin shaft 52 is formed into a cylindrical surface centered on the rotation axis. The internal space of the upper spin shaft 52 communicates with the through-hole 51b of the shielding plate 51. The upper spin shaft 52 is supported by a support arm 54 that extends horizontally above the shielding plate 51 so as to be rotatable relative to the support arm 54.

[0019] The nozzle 53 is disposed above the spin chuck 3. The nozzle 53 is supported by the support arm 54 in a state where it cannot rotate relative to the support arm 54. The nozzle 53 can be raised and lowered integrally with the shielding plate 51, the upper spin shaft 52, and the support arm 54. A discharge port 53a is provided at the lower end of the nozzle 53, and faces the center of the front surface Wf of the substrate W held by the spin chuck 3.

[0020] A shielding plate rotation drive mechanism 55 (FIG. 4) including an electric motor and the like is coupled to the shielding plate 51. The shielding plate rotation drive mechanism 55 rotates the shielding plate 51 and the upper spin shaft 52 relative to the support arm 54 around the rotation axis C1 in response to a rotation command from the control unit 4. A shielding plate lift drive mechanism 56 is coupled to the support arm 54. The shielding plate lift drive mechanism 56 lifts and lowers the shielding plate 51, the upper spin shaft 52, and the nozzle 53 together with the support arm 54 in the vertical direction Z in response to a lift command from the control unit 4. More specifically, the shielding plate lift drive mechanism 56 lifts and lowers the shielding plate 51, the upper spin shaft 52, and the nozzle 53 together with the support arm 54 between a blocking position (the position shown in the upper right of FIGS. 1, 6, and 7) in which the substrate-facing surface 51a is close to the front surface Wf of the substrate W held on the spin chuck 3 and substantially blocks the space above the front surface Wf from the surrounding atmosphere, and a retracted position (the positions shown in the middle and lower right of FIG. 7 and the position shown in FIG. 8) that is retracted significantly above the shielding position.

[0021] The upper end of the nozzle 53 is connected to a chemical liquid supply unit 61 , a rinse liquid supply unit 62 , an organic solvent supply unit 63 , a processing liquid supply unit 64 and a gas supply unit 65 .

[0022] The chemical supply unit 61 has a chemical pipe 611 connected to the nozzle 53 and a valve 612 installed in the chemical pipe 611. The chemical pipe 611 is connected to a chemical supply source. In this embodiment, the chemical may be any chemical that has the function of cleaning the surface Wf of the substrate W. For example, an acidic chemical may be used, such as a chemical containing at least one of hydrofluoric acid (HF), hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid. Furthermore, an alkaline chemical may be used, such as a chemical containing at least one of ammonia and a hydroxyl group. In this embodiment, hydrofluoric acid is used as the chemical. Therefore, when the valve 612 is opened in response to an opening / closing command from the control unit 4, the hydrofluoric acid chemical is supplied to the nozzle 53 and discharged from the discharge port 53a toward the center of the surface of the substrate W.

[0023] The rinse liquid supply unit 62 has a rinse liquid pipe 621 connected to the nozzle 53 and a valve 622 installed in the rinse liquid pipe 621. The rinse liquid pipe 621 is connected to a rinse liquid supply source. In this embodiment, DIW is used as the rinse liquid, and when the valve 622 is opened in response to an opening / closing command from the control unit 4, the DIW is supplied to the nozzle 53 and discharged from the discharge port 53a toward the center of the surface of the substrate W. Note that, other than DIW, any of carbonated water, electrolytic ion water, hydrogen water, ozone water, and diluted hydrochloric acid water (for example, about 10 ppm to 100 ppm) may be used as the rinse liquid.

[0024] The organic solvent supply unit 63 is a unit for supplying an organic solvent as a low-surface-tension liquid having a specific gravity greater than that of air and a surface tension lower than that of water. The organic solvent supply unit 63 has an organic solvent pipe 631 connected to the nozzle 53 and a valve 632 attached to the organic solvent pipe 631. The organic solvent pipe 631 is connected to a supply source of the organic solvent. In this embodiment, IPA is used as the organic solvent. When the valve 632 is opened in response to an opening / closing command from the control unit 4, IPA is supplied to the nozzle 53 and ejected from the ejection port 53a toward the center of the surface of the substrate W. In addition to IPA, other organic solvents that can be used include, for example, methanol, ethanol, acetone, EG (ethylene glycol), and HFE (hydrofluoroether). The organic solvent may be composed of only a single component, or may be a liquid mixed with other components. For example, it may be a mixture of IPA and acetone, or a mixture of IPA and methanol.

[0025] The processing liquid supply unit 64 supplies a processing liquid, which functions as a drying auxiliary liquid when drying the substrate W held on the spin chuck 3, to the surface Wf of the substrate W. The processing liquid supply unit 64 has a processing liquid pipe 641 connected to the nozzle 53 and a valve 642 installed in the processing liquid pipe 641. The processing liquid pipe 641 is connected to a processing liquid supply unit which functions as a processing liquid supply source. In this embodiment, a cyclohexanone oxime solution in which cyclohexanone oxime is dissolved as a sublimable substance in IPA is used as the processing liquid. In this specification, "sublimable" means that a single substance, compound, or mixture has the property of undergoing phase transition from solid to gas or from gas to solid without passing through a liquid state, and a "sublimable substance" means a substance having such sublimability. The processing liquid will be described in detail later.

[0026] 5 is a diagram showing the configuration of the processing liquid supply unit. In the figure, the symbols FB and CC represent a "fluid box" and a "cabinet," respectively. In this embodiment, a processing liquid pipe 641 is extended into the fluid box FB of the processing liquid supply unit 400, and a valve 642 is attached to the processing liquid pipe 641 within the fluid box FB, making it possible to switch between supplying and stopping the supply of the processing liquid.

[0027] The processing liquid supply unit 400 has a stock solution tank 401 that stores a cyclohexanone oxime solution as a stock solution of the processing liquid, and a diluent tank 405 that stores a solvent (IPA in this embodiment) having the same name as the solvent contained in the stock solution as a diluent. The stock solution tank 401 is connected to a first individual flow path 412 of a mixing valve 409 by a first individual pipe 402. On the other hand, the diluent tank 405 is connected to a second individual flow path 413 of the mixing valve 409 by a second individual pipe 406.

[0028] The concentrate in the concentrate tank 401 is sent to a mixing valve 409 by a first pump 403 installed in a first individual pipe 402. The flow rate of the concentrate sent from the concentrate tank 401 to the mixing valve 409 can be changed by a first electric valve 404 that opens and closes the inside of the first individual pipe 402. Similarly, the diluent in the diluent tank 405 is sent to the mixing valve 409 by a second pump 407 installed in a second individual pipe 406. The flow rate of the diluent sent from the diluent tank 405 to the mixing valve 409 can be changed by a second electric valve 408 that opens and closes the inside of the second individual pipe 406.

[0029] In this embodiment, both the first motorized valve 404 and the second motorized valve 408 are motorized needle valves. However, at least one of the first motorized valve 404 and the second motorized valve 408 may be a motorized valve other than a motorized needle valve. Note that the configuration of a motorized needle valve is well known and will not be described in detail, but the opening / closing and opening degree of the motorized valves 404 and 408 are controlled by the control unit 4.

[0030] 5, in addition to the first individual flow path 412 and the second individual flow path 413, the mixing valve 409 has a first check valve 410 that prevents backflow of the liquid in the first individual flow path 412, a second check valve 411 that prevents backflow of the liquid in the second individual flow path 413, and a collecting flow path 414 connected to the downstream ends of the first individual flow path 412 and the second individual flow path 413. Therefore, when the control unit 4 opens both the first electric valve 404 and the second electric valve 408, the stock solution and the diluent mix with each other while flowing downstream inside the collecting flow path 414 of the mixing valve 409 (flow mixing process). As a result, the stock solution (cyclohexanone oxime solution) is diluted with the diluent (IPA), and a treatment liquid with a desired concentration is produced.

[0031] The collecting flow path 414 of the mixing valve 409 is connected to a processing liquid pipe 641. Furthermore, as shown in FIG. 5, an in-line mixer 415 for stirring the processing liquid is disposed in the processing liquid pipe 641 upstream of the valve 642. The in-line mixer 415 has a pipe 415p disposed in the processing liquid pipe 641. Furthermore, a stirring fin 415f is disposed within the pipe 415p. The stirring fin 415f has a structure twisted around an axis extending in the direction of liquid flow. Therefore, the in-line mixer 415 functions as a static mixer. In other words, in the processing liquid supply unit 400, the undiluted liquid and the diluted liquid supplied from the undiluted liquid tank 401 and the diluted liquid tank 405 are mixed in the mixing valve 409 and then further mixed in the in-line mixer 415. This allows the sublimable substance and the solvent to be uniformly mixed.

[0032] The processing liquid supply unit 400 includes a branch pipe 416 branching from a processing liquid pipe 641. The upstream end of the branch pipe 416 is connected to the processing liquid pipe 641. A portion of the processing liquid in the processing liquid pipe 641 passes through the upstream end of the branch pipe 416 and is supplied to the nozzle 53. On the other hand, the remaining processing liquid in the processing liquid pipe 641 flows into the branch pipe 416 from its upstream end. The downstream end of the branch pipe 416 is connected to a replenishment tank 420. The downstream end of the branch pipe 416 may be connected to a processing liquid pipe 641 provided in another processing unit 1, or may be connected to a drainage device (not shown).

[0033] The processing liquid supply unit 400 may include a flow rate adjustment valve 418 that changes the flow rate of the processing liquid flowing from the processing liquid pipe 641 to the branch pipe 416. The opening degree of the flow rate adjustment valve 418 can be adjusted by the control unit 4. Therefore, the flow rate of the processing liquid flowing from the processing liquid pipe 641 to the branch pipe 416 is changed depending on the opening degree of the flow rate adjustment valve 418. The processing liquid supply unit 400 may include, instead of the flow rate adjustment valve 418, an orifice plate in which a hole having a diameter smaller than the inner diameter of the branch pipe 416 is formed. In this case, the processing liquid flows from the processing liquid pipe 641 to the branch pipe 416 at a flow rate that depends on the area of the hole in the orifice plate.

[0034] The treatment liquid supply unit 400 is equipped with a solution concentration meter 417 that measures the concentration of a sublimable substance in the treatment liquid. In FIG. 5, the solution concentration meter 417 is installed in the branch pipe 416. However, the location of the solution concentration meter 417 is not limited to this and may be any location downstream of the mixing valve 409. For example, the solution concentration meter 417 may be installed upstream or downstream of the in-line mixer 415, or may be installed in the nozzle 53. Alternatively, the solution concentration meter 417 may measure the concentration of the treatment liquid discharged from the nozzle 53.

[0035] The solution concentration meter 417 is an optical densitometer. The solution concentration meter 417 may be a concentration meter other than an optical densitometer. The control unit 4 changes the mixture ratio of the stock solution and the diluted solution, i.e., the ratio of the diluted solution to the stock solution, based on the detection value of the solution concentration meter 417. Specifically, the control unit 4 changes the aperture of at least one of the first electric valve 404 and the second electric valve 408 based on the detection value of the solution concentration meter 417. This increases or decreases the ratio of the sublimable substance contained in the treatment solution, and the concentration of the sublimable substance (cyclohexanone oxime) in the treatment solution is adjusted to a value within a set concentration range. The concentration range will be described in detail later.

[0036] The processing liquid supply unit 400 may include a replenishment tank 420 that stores a replenishment liquid to be supplied to the raw liquid tank 401. The replenishment tank 420 is connected to the raw liquid tank 401 by a replenishment pipe 421. The replenishment liquid in the replenishment tank 420 is sent to the raw liquid tank 401 by a replenishment pump 422 installed in the replenishment pipe 421. The replenishment liquid is a cyclohexanone oxime solution. The concentration of the sublimable substance in the replenishment liquid is lower than the concentration of the sublimable substance in the raw liquid.

[0037] The processing liquid supply unit 400 includes a solvent pipe 423 that supplies a solvent (IPA) into the replenishment tank 420, and a solvent valve 424 that opens and closes the inside of the solvent pipe 423. The processing liquid supply unit 400 further includes a circulation pipe 425 that circulates the replenishment liquid in the replenishment tank 420, a circulation pump 426 that sends the replenishment liquid in the replenishment tank 420 to the circulation pipe 425, and a circulation concentration meter 427 that measures the concentration of a sublimable substance in the replenishment liquid in the circulation pipe 425. The upstream end and downstream end of the circulation pipe 425 are connected to the replenishment tank 420.

[0038] The downstream end of a branch pipe 416 branching from the processing liquid pipe 641 is connected to a replenishment tank 420. The processing liquid flowing through the processing liquid pipe 641 is supplied to the replenishment tank 420 via the branch pipe 416 and mixed with the replenishment liquid in the replenishment tank 420. The concentration of the processing liquid is lower than the concentration of the sublimable substance in the original liquid. The sublimable substance in the replenishment liquid in the replenishment tank 420 is detected by a circulation concentration meter 427. If the concentration of the sublimable substance in the replenishment liquid is higher than the reference concentration, the control unit 4 opens the solvent valve 424 and supplies the solvent (IPA) into the replenishment tank 420. This reduces the concentration of the sublimable substance in the replenishment liquid and adjusts it to the reference concentration.

[0039] The concentrate in the concentrate tank 401 contains a sublimable substance and a solvent. When the solvent evaporates from the concentrate, the concentration of the sublimable substance in the concentrate increases, and the sublimable substance may precipitate. In this case, the upstream end of the first individual pipe 402 may become clogged with solid sublimable substance, and the concentrate may not flow or may barely flow through the first individual pipe 402. By supplying the replenisher in the replenisher tank 420 to the concentrate tank 401, the concentration of the sublimable substance in the concentrate can be maintained below the saturation concentration, and precipitation of the sublimable substance can be prevented.

[0040] The supply of replenishment liquid from the replenishment tank 420 to the concentrate tank 401 may be performed periodically, or may be performed according to the number of times the concentrate in the concentrate tank 401 is sent to the first individual pipe 402. Alternatively, the concentration of the sublimable substance in the concentrate in the concentrate tank 401 may be measured with a concentration meter, and the replenishment liquid may be supplied from the replenishment tank 420 to the concentrate tank 401 according to the detected value of the concentration meter. In either case, the concentrate in the concentrate tank 401 is diluted with the replenishment liquid, thereby preventing the upstream end of the first individual pipe 402 from being clogged with solid sublimable substance.

[0041] 3, when the valve 642 is opened in response to an opening / closing command from the control unit 4, the processing liquid (a cyclohexanone oxime solution adjusted to a desired concentration) supplied from the processing liquid supply unit 64 is supplied to the nozzle 53 and discharged from the discharge port 53a toward the center of the surface of the substrate W.

[0042] The gas supply unit 65 has a gas supply pipe 651 connected to the nozzle 53 and a valve 652 for opening and closing the gas supply pipe 651. The gas supply pipe 651 is connected to a gas supply source. In this embodiment, dehumidified nitrogen gas is used as the gas, and when the valve 652 is opened in response to an opening / closing command from the control unit 4, the nitrogen gas is supplied to the nozzle 53 and sprayed from the outlet 53a toward the center of the surface of the substrate W. Note that, instead of nitrogen gas, an inert gas such as dehumidified argon gas may be used as the gas.

[0043] In the processing unit 1, an exhaust tub 80 is provided to surround the spin chuck 3. A plurality of cups 81, 82 (a first cup 81 and a second cup 82) are disposed between the spin chuck 3 and the exhaust tub 80, and a plurality of guards 84-86 (a first guard 84 to a third guard 86) are provided to receive processing liquid splashed around the substrate W. Guard lifting / lowering drive mechanisms 87-89 (first to third guard lifting / lowering drive mechanisms 87-89) are connected to the guards 84-86, respectively. The guard lifting / lowering drive mechanisms 87-89 independently raise and lower the guards 84-86 in response to lifting / lowering commands from the control unit 4. The first guard lifting / lowering drive mechanism 87 is not shown in FIG. 3.

[0044] The control unit 4 has an arithmetic unit such as a CPU, a storage unit such as a fixed memory device or a hard disk drive, and an input / output unit. The storage unit stores a program executed by the arithmetic unit. The control unit 4 controls each part of the apparatus in accordance with the program, thereby performing the substrate processing shown in FIG. 6 using the processing liquid described below. The processing liquid and the substrate processing method will be described in detail below.

[0045] <<Processing liquid>> Next, the treatment liquid used in this embodiment will be described below. The treatment liquid of this embodiment contains at least cyclohexanone oxime and a solvent. The treatment liquid of this embodiment functions to assist in a drying process for removing liquid present on the pattern-formed surface of the substrate.

[0046] Cyclohexanone oxime is represented by the following chemical formula (1), and can function as a sublimable substance in the treatment liquid of this embodiment.

[0047] [ka]

[0048] Cyclohexanone oxime has the following physical properties: a freezing point of 90.5°C, a boiling point of 210°C, a vapor pressure of 0.00717 Torr to 251.458 Torr (0.96 Pa to 33.52 kPa), an entropy of fusion ΔS of 30.0 J / mol·K, and an n-octanol / water partition coefficient of +1.2. The freezing point of cyclohexanone oxime prevents poor solidification (freezing) due to freezing point depression in narrow spaces on the pattern formation surface. It also eliminates the need for a refrigerant during solidification.

[0049] Cyclohexanone oxime is preferably present in the treatment liquid in a state of being dissolved in a solvent.

[0050] The content of cyclohexanone oxime can be appropriately set depending on, for example, the supply conditions when supplying the treatment liquid onto the pattern-formed surface of the substrate, but is preferably 0.1 vol% to 10 vol% of the total volume of the treatment liquid, more preferably 1.25 vol% to 5 vol%, and particularly preferably 2 vol% to 4 vol%. By setting the cyclohexanone oxime content to 0.1 vol% or more, pattern collapse in partial or localized regions can be more effectively suppressed even on substrates with fine patterns with high aspect ratios. On the other hand, by setting the cyclohexanone oxime content to 10 vol% or less, the solubility of cyclohexanone oxime in solvents at room temperature is improved, allowing for uniform dissolution. Furthermore, in this specification, "solubility" means that 10 g or more of cyclohexanone oxime can be dissolved in 100 g of solvent at 23°C, for example.

[0051] The solvent can function as a solvent for dissolving cyclohexanone oxime, and is specifically at least one solvent selected from the group consisting of alcohols, ketones, ethers, cycloalkanes, and water.

[0052] The alcohols are not particularly limited, and examples thereof include methyl alcohol (melting point: −98° C., n-octanol / water partition coefficient: −0.82 to −0.66), ethyl alcohol (melting point: −117° C., n-octanol / water partition coefficient: −0.32), isopropyl alcohol (melting point: −90° C., n-octanol / water partition coefficient: +0.05), n-butyl alcohol (melting point: −90° C., n-octanol / water partition coefficient: +0.88), tert-butyl alcohol (melting point: 25° C., n-octanol / water partition coefficient: +0.3), and cyclohexanol (melting point: 23° C. to 25° C., n-octanol / water partition coefficient: +1.2).

[0053] The ketones are not particularly limited, and examples thereof include acetone (melting point: −95° C., n-octanol / water partition coefficient: −0.24).

[0054] The ethers are not particularly limited, and examples thereof include propylene glycol monomethyl ether acetate (melting point: −87° C., n-octanol / water partition coefficient: +0.43).

[0055] The cycloalkanes are not particularly limited, and examples thereof include cyclohexane (melting point: 7° C., n-octanol / water partition coefficient: +3.4).

[0056] The water is not particularly limited, and examples thereof include pure water.

[0057] All of the exemplified solvents can be used alone in combination with cyclohexanone oxime, or two or more of the exemplified solvents can be used in combination with cyclohexanone oxime.

[0058] The solvent is preferably one in which cyclohexanone oxime has good solubility.

[0059] Furthermore, among the solvents given as examples, isopropyl alcohol and the like can be mentioned from the viewpoint of being able to effectively prevent pattern collapse in partial or localized regions.

[0060] The n-octanol / water partition coefficient of the solvent is preferably in the range of −0.85 to +1.5, more preferably in the range of −0.82 to +1.2, and particularly preferably in the range of 0 to +1.2.

[0061] The vapor pressure of the solvent is preferably 500 Pa or higher at room temperature, more preferably 1000 Pa or higher, and particularly preferably 5000 Pa or higher. The greater the difference between the vapor pressure of the solvent and that of cyclohexanone oxime, the more likely it is that a solidified film will be formed even when the concentration of cyclohexanone oxime is low. As a result, processing costs and residues can be reduced. From the perspective of reducing the load on piping and the like due to vapor pressure, the vapor pressure of the solvent is preferably set to 10 KPa or lower.

[0062] The method for producing the treatment solution according to this embodiment is not particularly limited, and examples thereof include a method in which cyclohexanone oxime crystals are added to a solvent at room temperature and atmospheric pressure so as to achieve a certain content. Note that "atmospheric pressure" refers to an environment of 0.7 to 1.3 atmospheres, with standard atmospheric pressure (1 atmosphere, 1013 hPa) at the center.

[0063] In the method for producing the treatment liquid, cyclohexanone oxime crystals may be added to a solvent, followed by filtration. This reduces or prevents the generation of residues from the treatment liquid on the pattern-formed surface of a substrate when the treatment liquid is supplied onto the pattern-formed surface and used to remove the liquid. The filtration method is not particularly limited, and for example, filter filtration or the like can be used.

[0064] The treatment liquid of this embodiment can be stored at room temperature. However, from the viewpoint of suppressing changes in the concentration of cyclohexanone oxime due to evaporation of the solvent, it is preferable to store it at a low temperature (for example, about 5°C). When using a treatment liquid stored at a low temperature, it is preferable to use the treatment liquid after allowing the temperature of the treatment liquid to return to the usage temperature or room temperature, etc., from the viewpoint of preventing the inclusion of moisture due to condensation.

[0065] <<Substrate processing method>> Next, a substrate processing method using the substrate processing apparatus 100 shown in Fig. 1 will be described with reference to Fig. 6. Fig. 6 is a diagram showing the contents of the substrate processing performed in the substrate processing apparatus of Fig. 1. In Fig. 6 (and Figs. 7 and 8 described later), a flowchart of the substrate processing performed in one processing unit 1 is shown on the left side. In addition, the upper right, middle right, and lower right sections are schematic diagrams of a liquid film formation process, a solidified film formation process, and a sublimation process, respectively, and an enlarged view of a portion of the surface Wf of the substrate W. However, for ease of understanding, the dimensions and number of each part are exaggerated or simplified as necessary.

[0066] The processing object in the substrate processing apparatus 100 is, for example, a silicon wafer, and an uneven pattern PT is formed on the surface Wf, which is the pattern formation surface. In this embodiment, the protrusions PT1 have a height in the range of 100 to 600 nm and a width in the range of 5 to 50 nm. The shortest distance between two adjacent protrusions PT1 (the shortest width of the recess) is in the range of 5 to 150 nm. The aspect ratio of the protrusions PT1, i.e., the value obtained by dividing the height by the width (height H / width WD), is in the range of 5 to 35.

[0067] The pattern PT may also be a pattern in which line-shaped patterns formed by minute trenches are repeatedly arranged. The pattern PT may also be formed by providing a plurality of minute holes (voids or pores) in a thin film. The pattern PT includes, for example, an insulating film. The pattern PT may also include a conductive film. More specifically, the pattern PT is formed of a laminated film in which a plurality of films are stacked, and may further include an insulating film and a conductive film. The pattern PT may also be a pattern composed of a single layer film. The insulating film may be a silicon oxide film or a silicon nitride film. The conductive film may be an amorphous silicon film doped with impurities to reduce resistance, or may be a metal film (e.g., a TiN film). The pattern PT may also be formed in the front end or the back end. The pattern PT may also be a hydrophobic film or a hydrophilic film. An example of a hydrophilic film is a TEOS film (a type of silicon oxide film).

[0068] 6 are performed in an atmospheric pressure environment unless otherwise specified. Here, the atmospheric pressure environment refers to an environment of 0.7 atmospheres or more and 1.3 atmospheres or less, with the standard atmospheric pressure (1 atmosphere, 1013 hPa) at the center. In particular, when the substrate processing apparatus 100 is placed in a clean room where positive pressure is maintained, the environment of the surface Wf of the substrate W becomes higher than 1 atmosphere.

[0069] Before an unprocessed substrate W is loaded into the processing unit 1, the control unit 4 issues commands to each component of the apparatus, and the processing unit 1 is set to its initial state. That is, the shutter 23 (FIGS. 1 and 2) is closed by the shutter opening / closing mechanism 22. The spin chuck 3 is positioned and stopped at a position suitable for loading the substrate W by the substrate rotation drive mechanism 34, and the chuck pins 31 are opened by a chuck opening / closing mechanism (not shown). The shielding plate 51 is positioned at a retracted position by the shielding plate lifting / lowering drive mechanism 56, and rotation of the shielding plate 51 by the shielding plate rotation drive mechanism 55 is stopped. All of the guards 84 to 86 have been moved downward and positioned. Furthermore, all of the valves 612, 622, 632, 642, and 652 are closed.

[0070] When an unprocessed substrate W is transported by the substrate transport robot 111, the shutter 23 opens. In synchronization with the opening of the shutter 23, the substrate W is transported into the internal space 21 of the chamber 2 by the substrate transport robot 111 and transferred to the spin chuck 3 with the front surface Wf facing upward. Then, the chuck pins 31 are closed, and the substrate W is held by the spin chuck 3 (Step S1: Transporting the Substrate).

[0071] After the substrate W is loaded, the substrate transport robot 111 retreats to the outside of the chamber 2, and the shutter 23 closes again. Then, the control unit 4 controls the motor of the substrate rotation drive mechanism 34 to rotate the spin chuck 3 at a predetermined processing speed (within a range of approximately 10 to 3000 rpm, for example, 800 to 1200 rpm). ) and maintains that processing speed. The control unit 4 also controls the shielding plate lifting drive mechanism 56 to lower the shielding plate 51 from the retracted position to the shielding position (step S2). The control unit 4 also controls the guard lifting drive mechanisms 87 to 89 to raise the first guard 84 to the third guard 86 to their upper positions, thereby positioning the first guard 84 opposite the peripheral edge surface of the substrate W.

[0072] When the rotation of the substrate W reaches the processing speed, the control unit 4 then opens the valve 612. This causes a chemical liquid (HF in this embodiment) to be discharged from the discharge port 53a of the nozzle 53 and supplied to the front surface Wf of the substrate W. On the front surface Wf of the substrate W, the HF is subjected to centrifugal force due to the rotation of the substrate W and moves to the peripheral edge of the substrate W. As a result, the entire front surface Wf of the substrate W is subjected to chemical cleaning with HF (step S3). At this time, the HF that has reached the peripheral edge of the substrate W is discharged from the peripheral edge to the side of the substrate W, received by the inner wall of the first guard 84, and sent to a waste liquid treatment facility outside the apparatus along a drainage path (not shown). This chemical cleaning with the supplied HF continues for a predetermined cleaning time, after which the control unit 4 closes the valve 612 to stop the discharge of HF from the nozzle 53.

[0073] Following the chemical cleaning, a rinse process using a rinse liquid (DIW) is performed (step S4). During this DIW rinse, the control unit 4 opens the valve 622 while maintaining the positions of the first guard 84 to the third guard 86. As a result, DIW is supplied as a rinse liquid from the outlet 53a of the nozzle 53 to the center of the front surface Wf of the substrate W that has been subjected to the chemical cleaning process. The DIW is then moved to the periphery of the substrate W by centrifugal force due to the rotation of the substrate W. As a result, HF adhering to the substrate W is washed away by the DIW. At this time, the DIW discharged from the periphery of the substrate W is discharged from the periphery of the substrate W to the side of the substrate W and, like HF, is sent to a waste liquid treatment facility outside the apparatus. This DIW rinse continues for a predetermined rinse time. After this time has elapsed, the control unit 4 closes the valve 622 to stop the discharge of DIW from the nozzle 53.

[0074] After the DIW rinse is completed, a replacement process using an organic solvent (IPA in this embodiment) having a surface tension lower than that of the DIW is performed (step S5). In the IPA replacement, the control unit 4 controls the guard lifting / lowering drive mechanisms 87 and 88 to lower the first guard 84 and the second guard 85 to their lower positions, thereby causing the third guard 86 to face the peripheral edge surface of the substrate W. Then, the control unit 4 opens the valve 632. As a result, IPA is discharged as a low-surface-tension liquid from the discharge port 53a of the nozzle 53 toward the center of the front surface Wf of the substrate W to which the DIW is attached. The IPA supplied to the front surface Wf of the substrate W is subjected to centrifugal force due to the rotation of the substrate W and spreads over the entire front surface Wf of the substrate W. As a result, the DIW (rinse liquid) attached to the front surface Wf of the substrate W is replaced with IPA over the entire front surface Wf of the substrate W. The IPA moving on the surface Wf of the substrate W is discharged from the peripheral edge of the substrate W to the side of the substrate W, received by the inner wall of the third guard 86, and sent to a recovery facility along a recovery path (not shown). This IPA replacement continues for a predetermined replacement time, and when that time has elapsed, the control unit 4 closes the valve 632 to stop the discharge of IPA from the nozzle 53.

[0075] After the IPA substitution, a sublimation drying step (step S6) corresponding to the first embodiment of the substrate processing method of the present invention is performed. This sublimation drying step includes a liquid film formation step (step S6-1) of forming a liquid film of the processing liquid, a solidified film formation step (step S6-2) of solidifying the liquid film of the processing liquid to form a solidified film of cyclohexanone oxime, and a sublimation step (step S6-3) of sublimating the solidified film and removing it from the surface Wf of the substrate W.

[0076] In step S6-1, the control unit 4 controls the second guard lifting / lowering drive mechanism 88 to raise the second guard 85 to the upper position, thereby causing the second guard 85 to face the peripheral edge surface of the substrate W. Then, the control unit 4 opens the valve 642. As a result, as shown in the upper right part of FIG. 6, the processing liquid (cyclohexanone oxime solution) is discharged as a drying auxiliary liquid from the discharge port 53a of the nozzle 53 toward the center of the surface Wf of the substrate W to which the IPA is attached, and is supplied to the surface Wf of the substrate W. The processing liquid on the surface Wf of the substrate W is subjected to centrifugal force due to the rotation of the substrate W and spreads over the entire surface Wf of the substrate W. As a result, the IPA attached to the surface Wf of the substrate W is replaced by the processing liquid over the entire surface Wf of the substrate W, and a liquid film LF of the processing liquid is formed on the surface Wf, as shown in the upper right part of FIG. 6. The thickness of the liquid film LF is greater than the height of the convex portions PT1, and the entire pattern PT is immersed in the liquid film LF. Furthermore, it is desirable to adjust the thickness of the liquid film LF by appropriately changing the rotation speed of the substrate W within a range of 300 rpm to 3000 rpm depending on the concentration of cyclohexanone oxime contained in the processing liquid and the height and aspect ratio of the convex portions PT1. For example, if a thick liquid film LF is desired, the rotation speed can be set low, and conversely, if a thin liquid film LF is desired, the rotation speed can be set low. Once a liquid film LF having a desired thickness has been formed in this way, the control unit 4 closes the valve 642 to stop the discharge of the processing liquid from the nozzle 53.

[0077] In the next step S6-2, the control unit 4 opens the valve 652. As a result, as shown in the middle right of FIG. 6 , dehumidified nitrogen gas is sprayed toward the surface Wf of the substrate W, which is rotating and covered with the liquid film LF of the processing liquid. In this embodiment, the rotation of the substrate W promotes evaporation of the solvent component in the processing liquid, i.e., IPA. Accordingly, the concentration of the solute component in the processing liquid, i.e., cyclohexanone oxime, increases, exceeding the saturated concentration of the solvent (IPA) (or the heat of vaporization is removed). As a result, cyclohexanone oxime, a sublimable substance contained in the liquid film LF of the processing liquid, precipitates, forming a solid solidified film SF on the surface Wf of the substrate W. Furthermore, nitrogen gas is sprayed in parallel with the rotation of the substrate W to promote the deposition of the solidified film SF. The timing of opening the valve 652, i.e., the timing of starting the discharge of nitrogen gas, may be either before or after the start of deposition of cyclohexanone oxime. Furthermore, although the discharge of nitrogen gas is not an essential component for forming a solidified film of cyclohexanone oxime, it is desirable to use the discharge of nitrogen gas in combination in order to improve throughput.

[0078] Next, the control unit 4 executes the sublimation step (step S6-3). The control unit 4 controls the second guard lifting / lowering drive mechanism 88 to lower the second guard 85 to the lower position, thereby positioning the third guard 86 opposite the peripheral edge surface of the substrate W. In this embodiment, the control unit 4 maintains the rotation speed of the substrate W from the solidified film SF formation step (step S6-2), but may also accelerate it to a high speed. The control unit 4 also controls the shielding plate rotation drive mechanism 55 to rotate the shielding plate 51 in the same direction and at the same speed as the rotation of the substrate W. As the substrate W rotates, the contact speed between the solidified film SF and the surrounding atmosphere increases. This accelerates the sublimation of the solidified film SF, enabling the solidified film SF to be sublimated within a short period of time. However, the rotation of the shielding plate 51 is not a required component of the sublimation step and is an optional component.

[0079] Furthermore, in the sublimation step S6-3, the control unit 4 maintains the valve 652 open from the formation of the solidified film SF, and dehumidified nitrogen gas is discharged from the outlet 53a of the nozzle 53 toward the center of the surface Wf of the rotating substrate W, as shown in the lower right of FIG. 6. This allows the sublimation step to be performed while maintaining a low humidity in the shielded space between the surface Wf of the substrate W and the substrate-facing surface 51a of the shielding plate 51. In this sublimation step S6-3, heat of sublimation is removed as the solidified film SF sublimes, maintaining the solidified film SF at or below the freezing point (melting point) of cyclohexanone oxime. This effectively prevents the sublimable substance constituting the solidified film SF, i.e., cyclohexanone oxime, from melting. Because no liquid phase exists between the patterns PT on the surface Wf of the substrate W, the substrate W can be dried while mitigating the problem of the patterns PT collapsing.

[0080] When a predetermined sublimation time has elapsed since the start of the sublimation drying step S6, in step S7, the control unit 4 controls the motor of the substrate rotation drive mechanism 34 to stop the rotation of the spin chuck 3. The control unit 4 also controls the shielding plate rotation drive mechanism 55 to stop the rotation of the shielding plate 51, and controls the shielding plate lift drive mechanism 56 to lift the shielding plate 51 from the shielding position to position it at the retracted position. The control unit 4 also controls the third guard lift drive mechanism 89 to lower the third guard 86, and retracts all of the guards 86 to 88 downward from the peripheral edge surface of the substrate W.

[0081] Thereafter, the control unit 4 controls the shutter opening / closing mechanism 22 to open the shutter 23 (FIGS. 1 and 2), and then the substrate transfer robot 111 enters the internal space of the chamber 2 and transfers the processed substrate W, which has been released from the chuck pins 31, out of the chamber 2 (step S8). Note that, once the transfer of the substrate W is completed and the substrate transfer robot 111 moves away from the processing unit 1, the control unit 4 controls the shutter opening / closing mechanism 22 to close the shutter 23.

[0082] As described above, in this embodiment, IPA adhering to the surface Wf of the substrate W is replaced with a processing liquid in which cyclohexanone oxime, a sublimable substance, is dissolved in a solvent, thereby forming a liquid film LF. Next, cyclohexanone oxime is precipitated to form a solidified film SF of cyclohexanone oxime, which is then sublimated. In other words, the solidified film SF is removed from the surface Wf of the substrate W without passing through a liquid state. Therefore, by using the substrate processing method according to this embodiment, it is possible to dry the substrate W while preventing the pattern PT from collapsing.

[0083] In the above embodiment, the mixing valve 409 is connected to the stock solution tank 401 by a first individual pipe 402 and to the dilute solution tank 405 by a second individual pipe 406. The concentration of the processing solution is adjusted by supplying the processing solution stock solution (cyclohexanone oxime solution) from the stock solution tank 401 and the dilute solution (IPA) from the dilute solution tank 405 to the mixing valve 409 and mixing them. Therefore, the expensive stock solution provided by the vendor can be diluted and adjusted to a concentration suitable for substrate processing conditions such as the type of substrate W and rotation speed, as will be described in detail later. Furthermore, even if the concentrations of the processing solution and stock solution stored in the replenishment tank 420 fluctuate slightly, the concentration of the sublimable substance (cyclohexanone oxime) in the processing solution can be stabilized, and the substrate W can be dried well.

[0084] Second Embodiment In the first embodiment, as shown in the middle right of FIG. 6 , with the shielding plate 51 positioned at the blocking position, nitrogen gas is sprayed from the outlet 53a of the nozzle 53 toward the center of the surface Wf of the substrate W to solidify the entire liquid film LF. Therefore, dehumidified nitrogen gas is directly supplied to the center of the surface Wf and its periphery, and the solidification process progresses relatively quickly. In contrast, the amount of vaporized solvent (IPA) in the nitrogen gas increases with increasing distance from the center in the radial direction of the substrate W. As a result, the solidification rate at the periphery of the liquid film LF is slower than that at the center, which may make it difficult to achieve uniform solidification across the entire surface Wf of the substrate W. Therefore, nitrogen gas may be sprayed toward the surface Wf of the substrate W using a dedicated nitrogen gas nozzle (second embodiment).

[0085] 7 is a diagram showing a second embodiment of the substrate processing method according to the present invention. The second embodiment differs significantly from the first embodiment in that a dedicated nozzle 7 is provided for ejecting dehumidified nitrogen gas toward the surface Wf of the substrate W, and the solidified film forming step (step S6-2) and the sublimation step (step S6-3) are performed using this nozzle 7. That is, the steps from loading the substrate (step S1) to forming a liquid film of the processing liquid (step S6-1) are performed in the same manner as in the first embodiment.

[0086] On the other hand, once the liquid film LF is formed, as shown in FIG. 7, the shielding plate 51 is raised from the shielding position to the retracted position (step S6-4). This creates a sufficient space for the nozzle 7 to scan horizontally between the surface Wf of the substrate W held by the spin chuck 3 and the shielding plate 51. Thereafter, as shown in the middle right of the figure, the nozzle 7 is caused to scan along the surface Wf of the rotating substrate W, while dehumidified nitrogen gas is ejected toward the surface Wf of the substrate W from the ejection port 71 provided at the lower end of the nozzle 7. Here, the scanning path of the nozzle 7 can be, for example, a path from directly above the center of the substrate W toward the radial direction of the substrate W. Alternatively, nitrogen gas may be continuously ejected from the nozzle 7 while scanning back and forth along this path. This allows dehumidified nitrogen gas to be directly supplied to each portion of the surface Wf of the substrate W. As a result, a solidified film SF can be formed with high uniformity over the entire surface Wf of the substrate W (step S6-5), compared to the first embodiment. Furthermore, the sublimation process (step S6-6) can also be performed with high uniformity over the entire surface Wf.

[0087] By performing this sublimation drying process (steps S6 (=S6-1, S6-4, S6-5, S6-6)), it is possible to more effectively prevent the pattern PT from collapsing while performing sublimation drying of the substrate W. Thereafter, as in the first embodiment, the rotation of the substrate is stopped (step S7) and the substrate is unloaded (step S8).

[0088] <Third embodiment> In the first embodiment, the shielding plate 51 is used in the entire sublimation drying step (step S6). In the second embodiment, the shielding plate 51 is used in part of the sublimation drying step (step S6), i.e., in forming a liquid film of the processing liquid (step S6-1). However, the shielding plate 51 is not an essential component in performing the sublimation drying step (step S6). For example, the entire sublimation drying step (step S6) may be performed without using the shielding plate 51 (third embodiment).

[0089] 8 is a diagram showing the contents of substrate processing performed in a third embodiment of the substrate processing method according to the present invention. In the third embodiment, the processing unit 1 shown in FIG. 1 is provided with a nozzle 7 for discharging nitrogen gas as in the second embodiment, and a processing liquid discharge nozzle 8 for discharging a processing liquid, and the following steps are performed.

[0090] In the third embodiment, the processes from substrate loading (step S1) to IPA replacement (step S5) are performed in the same manner as in the first and second embodiments. After the IPA replacement is completed, the sublimation drying process (step S6), which will be described next, is performed. First, the shielding plate 51 is raised from the shielding position to the retracted position (step S6-7). Subsequently, with the shielding plate 51 positioned at the retracted position, the processing liquid discharge nozzle 8 moves through the space formed between the shielding plate 51 and the front surface Wf of the substrate W held by the spin chuck 3, and is positioned directly above the center of the substrate W. The processing liquid discharge nozzle 8 is connected to the processing liquid pipe 641. The processing liquid is discharged from the processing liquid discharge nozzle 8 toward the front surface Wf of the rotating substrate W. As a result, a liquid film LF of the processing liquid is formed on the front surface Wf of the substrate W (step S6-8). After that, a solidified film SF is formed (step S6-5) in the same manner as in the second embodiment, and then the solidified film SF is removed by sublimation (step S6-6).

[0091] <Fourth embodiment> In the above first to third embodiments, the solidified film formation process (steps S6-2, S6-5) is performed while maintaining the rotation speed (number of rotations) of the substrate W constant, but in the solidified film formation process, a filling process (dwell) in which a sublimable substance is filled into the pattern PT by temporarily reducing the rotation speed of the substrate W may be performed in conjunction with the solidification process (fourth embodiment).

[0092] 9 is a timing chart of substrate processing performed in a fourth embodiment of the substrate processing method according to the present invention. In the figure, "processing liquid," "substrate rotation speed," and "N2 gas" indicate the timing of ejection of the processing liquid, changes in the rotation speed of the substrate W, and the timing of ejection of nitrogen gas, respectively. The fourth embodiment differs significantly from the first embodiment in that the solidified film formation step (step S6-2) includes a filling process (step S6-2a), but the remaining configuration is essentially the same as the first embodiment. Therefore, the following description will focus on the differences, and the same components will be denoted by the same reference numerals and will not be described again.

[0093] In the fourth embodiment, as shown in the figure, the processing liquid is discharged onto the surface Wf of the substrate W rotating at, for example, 300 rpm, to form a liquid film LF of the processing liquid (liquid film forming step: step S6- 1). At timing t1 when the liquid film forming step is completed, the control unit 4 closes the valve 642 to stop the discharge of the processing liquid from the nozzle 53, and then increases the rotation speed to 500 rpm and maintains this for a predetermined time (e.g., 2 seconds), thereby shaking off excess processing liquid from the substrate W. Note that in the liquid film forming step of step S6-1, after the rotation speed of the substrate W during the discharge of the processing liquid is increased to 500 rpm, the rotation speed of the substrate W may be maintained as is even after the discharge of the processing liquid is stopped.

[0094] Subsequently, the control unit 4 controls the motor of the substrate rotation drive mechanism 34 to decelerate the rotation speed to a rotation speed suitable for the filling process (100 rpm in this embodiment) (timing t3) and maintains that rotation speed until timing t4. While the substrate W is being rotated at this low speed (timings t3 to t4), the processing liquid leveling occurs, and the thickness of the liquid film LF is made uniform across the entire surface Wf of the substrate W. Therefore, simultaneously with the deposition of the sublimable substance (cyclohexanone oxime), the sublimable substance is uniformly introduced into the pattern PT across the entire surface Wf of the substrate W. Furthermore, because of the low rotation speed, the evaporated solvent component (IPA evaporation in this embodiment) tends to accumulate uniformly above the surface Wf of the substrate W, and the evaporation rate of the solvent component from the liquid film LF becomes uniform across the surface Wf of the substrate W. At timing t4, when the filling process of the sublimable substance (step S6-2a) is thus completed, the control unit 4 controls the motor of the substrate rotation drive mechanism 34 to increase the rotation speed over a period of time (= t5 - t4) to promote solidification. Furthermore, while the velocity is being increased, the control unit 4 opens the valve 652 and discharges nitrogen gas toward the liquid film LF just before solidification. This causes the entire surface Wf of the substrate W to be solidified all at once. Subsequently, the sublimation step (step S6-3) is carried out.

[0095] As described above, in the fourth embodiment, since the filling process is included in the solidified film formation process, the variation in solidification time within the surface of the substrate W can be reduced, and the sublimable material can be grown in crystals more uniformly on the pattern PT.

[0096] Furthermore, in this embodiment, the sublimable substance filling process (step S6-2a) is performed with the blocking plate 51 lowered to the blocking position. This allows a uniform atmosphere of solvent components to be formed on the surface Wf of the substrate W, and further reduces variations in solidification time within the surface of the substrate W. As a result, the substrate W can be dried more effectively while preventing collapse of the pattern PT under various substrate processing conditions.

[0097] In the fourth embodiment, after the sublimable substance filling process (step S6-2a), the rotation speed is increased and nitrogen gas is ejected in parallel, but the ejection of nitrogen gas may be started before or after the rotation speed is increased. Also, the time (= t4 - t5) for rotating the substrate W at a low speed may be set to, for example, 15 to 35 seconds, and more preferably, 20 to 30 seconds.

[0098] Furthermore, when performing the filling process, the sublimation step (step S6-3) may be started before the sublimable substance filled between the patterns PT is completely solidified. In other words, the solid of the sublimable substance may be sublimated while being maintained in a pre-crystallization transition state before crystallization. This allows the solid of the sublimable substance to be removed from the surface Wf of the substrate W without passing through a crystallized state. Therefore, the influence of stress caused by the crystallization of the solid of the sublimable substance can be reduced, and the collapse of the patterns PT on the substrate W can be more effectively reduced.

[0099] Furthermore, in the fourth embodiment, the filling process (step S6-2a) is included in the solidified film formation process (step S6-2) of the first embodiment, but the above-mentioned filling process may also be included in the solidified film formation process (step S6-5) of the second or third embodiment.

[0100] Fifth Embodiment Although the first to fourth embodiments described above utilize the atmosphere blocking mechanism 5, applying the substrate processing method according to the present invention does not necessarily require the substrate processing apparatus to be equipped with the atmosphere blocking mechanism 5. In other words, the present invention can also be applied to a substrate processing apparatus that is not equipped with the atmosphere blocking mechanism 5.

[0101] As described above, step S6-1 corresponds to an example of the "liquid film forming step" of the present invention, steps S6-2 and S6-5 correspond to an example of the "solidified film forming step" of the present invention, and steps S6-3 and S6-6 correspond to an example of the "sublimation step" of the present invention. Furthermore, IPA corresponds to an example of the "solvent" of the present invention, but is not limited thereto. When mixing molten cyclohexanone oxime, the solvent is preferably one that is compatible with the molten cyclohexanone oxime. Furthermore, when dissolving cyclohexanone oxime as a solute, the solvent is preferably one that is soluble in cyclohexanone oxime. Specifically, for example, at least one selected from the group consisting of pure water, DIW, aliphatic hydrocarbons, aromatic hydrocarbons, esters, alcohols, ketones, cycloalkanes, and ethers can be used. More specifically, examples of the solvent include at least one selected from the group consisting of pure water, DIW, methanol, ethanol, IPA, butanol, n-butyl alcohol, ethylene glycol, propylene glycol, NMP, DMF, DMA, DMSO, hexane, toluene, PGMEA (propylene glycol monomethyl ether acetate), PGME (propylene glycol monomethyl ether), PGPE (propylene glycol monopropyl ether), PGEE (propylene glycol monoethyl ether), GBL, acetylacetone, 3-pentanone, 2-heptanone, ethyl lactate, cyclohexanone, dibutyl ether, HFE (hydrofluoroether), ethyl nonafluoroisobutyl ether, ethyl nonafluorobutyl ether, m-xylene hexafluoride, and cyclohexane.

[0102] In the above embodiment, the stock solution tank 401 and the diluent tank 405 correspond to examples of the "treatment solution storage section" and the "solvent storage section," respectively. The first individual pipe 402 and the second individual pipe 406 correspond to examples of the "first pipe" and the "second pipe," respectively. The mixing valve 409 corresponds to an example of the "mixing member" of the present invention. Furthermore, the stock solution stored in the stock solution tank 401 corresponds to the "treatment solution in which cyclohexanone oxime is dissolved in the same solvent as the solvent" of the present invention, and the treatment solution sent from the collecting flow path 414 of the mixing valve 409 via the treatment solution pipe 641 corresponds to the "concentration-adjusted treatment solution" of the present invention.

[0103] The present invention is not limited to the above-described embodiment, and various modifications other than those described above are possible without departing from the spirit of the present invention. For example, in the above-described embodiment, the sublimation step (steps S6-3, S6-6) is performed after the solidified film formation step (steps S6-2, S6-5) is completed, but the two steps may be partially overlapped.

[0104] Furthermore, in the above embodiment, in order to solidify the processing liquid in the solidified film formation process (steps S6-2, S6-5), the substrate W is rotated and nitrogen gas is ejected toward the front surface Wf of the substrate W, but the process may also be configured to further promote solidification by supplying a medium such as temperature-adjusted DIW to the back surface Wb (Figure 1) of the substrate W.

[0105] Furthermore, in the above embodiment, the concentration of the sublimable substance (cyclohexanone oxime) in the treatment liquid is adjusted by mixing the original liquid and the diluted liquid using the mixing valve 409, but the solvent may be supplied to the original liquid tank 401 from the diluted liquid tank 405 via a pipe (corresponding to an example of the "third pipe" of the present invention). In other words, the concentration may be adjusted in the original liquid tank 401, and the treatment liquid whose concentration has been adjusted may be sent from the original liquid tank 401 to the nozzle via the treatment liquid pipe 641. [Example]

[0106] Preferred embodiments of the present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples. Therefore, it is possible to carry out the present invention by making appropriate modifications within the scope of the above-mentioned gist, and all such modifications are included in the technical scope of the present invention.

[0107] <Relationship between concentration and rotation speed> In the manufacture of electronic components such as semiconductor devices and liquid crystal display devices, it is necessary to form a pattern with a high aspect ratio on the surface of a substrate such as a silicon wafer. However, it is becoming difficult to satisfactorily dry the substrate on which the pattern is formed. Therefore, as an example of a substrate having a pattern with a high aspect ratio, a substrate having a pattern with an aspect ratio of 18.4 (hereinafter referred to as "Substrate A") was prepared and the following verification was performed.

[0108] First, a substrate was treated using the treatment liquid described in Patent Document 1, i.e., a treatment liquid in which a sublimable substance (camphor) was dissolved in IPA (hereinafter referred to as the "conventional treatment liquid"), according to the procedure shown in Figure 6. Here, sublimation drying was performed using various combinations (rotation speed, concentration) while varying the rotation speed of the substrate and the concentration of the sublimable substance in the treatment liquid (hereinafter simply referred to as "concentration"). However, when the pattern collapse rate was examined for Substrate A after sublimation drying, the pattern collapsed at a rate of 100% or close to 100% in every combination.

[0109] In contrast, when a substrate was processed using the processing solution described in the above embodiment, i.e., a processing solution prepared by dissolving a sublimable substance (cyclohexanone oxime) in IPA (hereinafter referred to as the "processing solution of the present application"), according to the procedure shown in FIG. 6, it was confirmed that sublimation drying could be performed with a pattern collapse rate close to zero. Here, the solubility of cyclohexanone oxime in IPA is approximately 10% by volume. To uniformly disperse cyclohexanone oxime in IPA, the concentration of the processing solution of the present application is preferably set to 10% by volume or less. Therefore, processing solutions of the present application with concentrations of 1.25%, 2.5%, and 5% by volume were prepared, and sublimation drying was performed while the rotation speed in the sublimation drying process (step S6) was changed to six speeds: 500 rpm, 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, and 3000 rpm. The pattern collapse rate for each combination was then verified. The results are shown in FIG. 10. In the figure, the mark "◎" indicates that the pattern collapse rate was less than 1%, the mark "○" indicates that the pattern collapse rate was 1% or more but less than 5%, the mark "△" indicates that the pattern collapse rate was 5% or more but less than 20%, and the mark "×" indicates that the pattern collapse rate was 20% or more.

[0110] As is clear from FIG. 10, even substrate A with a high aspect ratio to the extent that pattern collapse cannot be prevented with a conventional processing liquid can be dried satisfactorily by using the processing liquid of the present invention.

[0111] Furthermore, the range where excellent results can be obtained (the dotted range in Figure 10) is proportional to the concentration and rotation speed. In other words, to effectively suppress or prevent pattern collapse, it is desirable to set the rotation speed of substrate A lower as the concentration decreases. As mentioned above, the solubility of cyclohexanone oxime in IPA is approximately 10% by volume, so it is desirable to set the concentration to 10% by volume or less. However, from the perspective of reducing the amount of sublimable substance (cyclohexanone oxime) used to reduce running costs and to reduce the rotation speed of substrate A, it is desirable to set the concentration to 5% by volume or less. On the other hand, lowering the concentration also reduces the absolute amount of sublimable substance contained in the processing solution. Therefore, to achieve good sublimation drying, it is desirable to set the concentration to at least 0.1% by volume.

[0112] Furthermore, when a substrate having an aspect ratio higher than that of the substrate A, specifically a substrate having a pattern with an aspect ratio of 22.6 (hereinafter referred to as "substrate B"), was prepared and subjected to the same experiment as above, it was found that the use of the treatment solution of the present invention makes it possible to perform sublimation drying while suppressing pattern collapse. In particular, when the substrate was treated according to the procedure shown in Figure 6 with a combination of a concentration of the treatment solution of the present invention of 0.76 vol% and a substrate rotation speed of 300 rpm, the pattern collapse rate was suppressed to 3.2%.

[0113] <Type of circuit board> In the manufacture of electronic components such as semiconductor devices and liquid crystal display devices, front-end and back-end processes are performed. For example, in the case of semiconductor devices such as LSIs, elements such as field effect transistors (FETs) and capacitors are formed on the surface of substrates such as silicon wafers in the front-end process. As miniaturization progresses, patterns with high aspect ratios are formed in the front-end process. The above-mentioned substrates A and B are also manufactured using the front-end process, but currently, substrates with an aspect ratio of 35 exist. When the processing solution of the present invention was used on these substrates, sublimation drying was possible while suppressing pattern collapse.

[0114] In addition, back-end processes form multiple wiring layers on the surface of substrates that have undergone front-end processes. The wiring pitch increases toward higher layers, taking into account connections to external terminals. Therefore, the aspect ratio of patterns fabricated in back-end processes is smaller than that of front-end processes, currently ranging from 6 to 7. However, due to technical demands such as reducing the electrical capacitance (inter-wiring capacitance) between adjacent wirings, back-end processes form patterns in interlayer insulating layers composed of low-dielectric-constant materials (low-k materials). For example, SiOC, which is SiO2 doped with carbon, is used. This SiOC has lower hardness than silicon wafers, etc. Therefore, even though the aspect ratio is relatively low, pattern collapse remains a major problem. When the processing solution of the present invention was used on such substrates, sublimation drying was achieved while suppressing pattern collapse.

[0115] <Substrate surface characteristics> When wet processing is performed on a substrate with a pattern formed on its surface, the surface of the substrate may be subjected to a hydrophilic treatment, such as irradiating it with ultraviolet light. This is done to make the surface hydrophilic, thereby making it easier for liquid to penetrate between the patterns. Note that "hydrophilic" here means, for example, a contact angle of 30 degrees or less.

[0116] On the other hand, when sublimation drying is performed after wet processing with this liquid, pattern collapse is likely to occur because the substrate surface is hydrophilic. In fact, when sublimation drying is performed using a conventional processing liquid according to the procedure shown in Figure 6, differences in pattern collapse performance occurred among substrates with the same pattern depending on the surface characteristics. In other words, sublimation drying was successful without pattern collapse for substrates with hydrophobic surface characteristics. In contrast, pattern collapse could not be suppressed for substrates with hydrophilic surface characteristics.

[0117] In contrast, when substrate processing is performed using the processing solution of the present invention according to the procedure described in the above embodiment, the substrate processing can be performed while suppressing pattern collapse, regardless of whether the substrate surface is hydrophobic or hydrophilic. In other words, by using the above substrate processing, substrates having hydrophilic or hydrophobic surfaces can be satisfactorily dried while preventing pattern collapse. [Industrial Applicability]

[0118] The present invention can be applied to the general substrate processing technology for processing substrates having patterns formed on their surfaces. [Explanation of symbols]

[0119] LF…Liquid film PT...pattern SF…solidified film W...Substrate Wf...(substrate) surface

Claims

1. a liquid film forming step of supplying a treatment liquid, in which a sublimable substance is dissolved in a solvent, onto a surface of a substrate on which a pattern has been formed, to form a liquid film of the treatment liquid on the surface of the substrate; a solidified film forming step of solidifying the liquid film of the treatment liquid to form a solidified film of the sublimable substance; a sublimation step of sublimating the solidified film and removing it from the surface of the substrate; Equipped with In the liquid film forming step, the substrate is rotated around a rotation axis parallel to a surface normal of the surface of the substrate, the solidified film forming step includes a step of rotating the substrate around the rotation axis at a rotation speed lower than the rotation speed of the substrate in the liquid film forming step to fill the sublimable substance into the pattern, and then ejecting an inert gas onto the surface of the substrate while increasing the rotation speed of the substrate to promote solidification of the liquid film of the processing liquid. A substrate processing method comprising:

2. a liquid film forming step of supplying a treatment liquid, in which a sublimable substance is dissolved in a solvent, onto a surface of a substrate on which a pattern has been formed, to form a liquid film of the treatment liquid on the surface of the substrate; a solidified film forming step of solidifying the liquid film of the treatment liquid to form a solidified film of the sublimable substance; a sublimation step of sublimating the solidified film and removing it from the surface of the substrate; Equipped with In the liquid film forming step, the substrate is rotated around a rotation axis parallel to a surface normal of the surface of the substrate, the solidified film forming step includes a step of rotating the substrate around the rotation axis at a rotation speed equal to or higher than the rotation speed of the substrate in the liquid film forming step while stopping the supply of the processing liquid to spin off a part of the processing liquid on the substrate, rotating the substrate around the rotation axis at a rotation speed lower than the rotation speed of the substrate in the liquid film forming step to fill the sublimable substance into the pattern, and then discharging an inert gas onto the surface of the substrate while increasing the rotation speed of the substrate. A substrate processing method comprising:

3. 3. The substrate processing method according to claim 2, The substrate processing method, wherein the solidified film forming step includes a step of increasing a rotation speed of the substrate after filling the pattern with the sublimable substance to promote solidification of the liquid film.

4. 3. The substrate processing method according to claim 2, The solidified film forming step is a step of forming a solidified film on the substrate after filling the pattern with the sublimable substance.

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