Substrate processing method and substrate processing apparatus

Abstract

[Problem]To reduce impurities remaining on a substrate after a chemical liquid treatment. [Solution] In a substrate processing method and a substrate processing apparatus according to the present invention, a chemical liquid is supplied to a substrate, on one main surface of which a rinse liquid film is formed. Consequently, a main flow region in which the chemical liquid flows toward the outside of the substrate is formed on a viscous bottom layer that is composed of the rinse liquid on the one main surface of the substrate, and a chemical liquid component contained in the chemical liquid is quickly diffused from the main flow region to the viscous bottom layer, and reaches the one main surface of the substrate so as to execute the chemical liquid treatment. Meanwhile, impurities are diffused later from the main flow region to the viscous bottom layer. Therefore, in the present invention, before the impurities are diffused from the main flow region to the viscous bottom layer and reach the one main surface, the rinse liquid is supplied to the one main surface that has been subjected to the chemical liquid treatment, and the chemical liquid and the impurities present in the main flow region are pushed away to the outside of the substrate. As a result, impurities remaining on the substrate after the chemical liquid treatment can be reduced.

Description

Substrate processing method and substrate processing apparatus

[0001] This invention relates to a substrate processing method and a substrate processing apparatus that perform a chemical treatment using a chemical solution and a rinse treatment using a rinse solution on a substrate. The disclosures in the specification, drawings, and claims of the following Japanese patent application are incorporated herein by reference in their entirety: Japanese Patent Application No. 2024-087640 (filed May 30, 2024).

[0002] There is known a substrate processing apparatus that supplies a chemical solution to a substrate held by a spin chuck to perform a chemical process such as etching. For example, in the apparatus described in Patent Document 1, after the chemical process, a rinse process is performed in which a rinse solution such as deionized water (DIW) is supplied to the substrate to wash away the chemical solution on the substrate, and a drying process is performed in which the rinse solution adhering to the substrate is shaken off from the substrate and dried.

[0003] Japanese Patent Application Laid-Open No. 2022-70067

[0004] In performing such substrate processing, reducing the number of particles remaining on the substrate is an important issue from the viewpoint of improving yield. Therefore, chemicals and rinse solutions are typically filtered to remove particles before being used in substrate processing. However, for chemicals such as hydrochloric acid (HCl) and hydrofluoric acid (HF), the particle concentration in the chemicals is higher than that in rinse solutions such as DIW, because the filters that can be used to remove particles are limited. Therefore, a substrate processing technology that can reduce the number of particles remaining on the substrate after chemical processing is desired.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a substrate processing method and a substrate processing apparatus that can reduce impurities remaining on a substrate after chemical processing.

[0006] A first aspect of the present invention is a substrate processing method comprising: a rinse liquid film forming step of supplying a rinse liquid to one main surface of the substrate to form a rinse liquid film on the one main surface of the substrate; a first chemical liquid step of supplying a chemical liquid containing a chemical liquid component toward the one main surface of the substrate having the rinse liquid film formed thereon in the rinse liquid film forming step, thereby forming a mainstream region on the one main surface of the substrate where the chemical liquid flows outward from the viscous bottom layer composed of the rinse liquid, and processing the one main surface of the substrate with the chemical liquid component that diffuses from the mainstream region into the viscous bottom layer and reaches the one main surface of the substrate; and a rinse step of supplying a rinse liquid to rinse the entire one main surface of the substrate before impurities contained in the chemical liquid and having a diffusion coefficient smaller than that of the chemical liquid component diffuse from the mainstream region into the viscous bottom layer and reach the one main surface of the substrate.

[0007] A second aspect of the present invention is a substrate processing apparatus comprising: a substrate holding unit that holds a substrate with one main surface of the substrate facing upward; a rinse liquid supply unit that supplies a rinse liquid to the one main surface of the substrate held by the substrate holding unit; a chemical liquid supply unit that supplies a chemical liquid to the one main surface of the substrate held by the substrate holding unit; and a control unit that controls the rinse liquid supply unit and the chemical liquid supply unit so as to perform the substrate processing method.

[0008] In the invention configured as described above, a chemical solution is supplied to a substrate having a rinse liquid film formed on one main surface of the substrate. At this time, as described below, a main region of the chemical solution is formed on a viscous bottom layer composed of the rinse liquid on one main surface of the substrate. In other words, in the main region, the chemical solution flows toward the outside of the substrate, pushing the rinse liquid on the viscous bottom layer away from the substrate. Meanwhile, in the viscous bottom layer, the flow velocity within the layer is extremely slow, so the rinse liquid is not immediately replaced by the chemical solution and remains. Therefore, immediately after the chemical solution is dispensed, a main region composed of the chemical solution and a viscous bottom layer composed of the rinse liquid are temporarily formed on one main surface of the substrate. The chemical solution may contain not only chemical solution components but also impurities such as particles. The diffusion coefficients of the chemical solution components and the impurities are compared, and the impurities' diffusion coefficient is smaller than that of the chemical solution components. Therefore, the chemical solution components in the main region diffuse quickly from the main region to the viscous bottom layer, reaching the one main surface of the substrate and performing chemical processing. Meanwhile, impurities diffuse from the main region to the viscous bottom layer with a delay. Therefore, in the present invention, before the impurities diffuse from the mainstream region into the viscous bottom layer and reach one main surface of the substrate, a rinse liquid is supplied to the entire one main surface that has been subjected to the above-mentioned chemical treatment, and the chemical liquid containing the impurities is washed away.

[0009] As described above, according to the present invention, it is possible to reduce impurities remaining on a substrate after chemical processing. Not all of the components of each of the above-described aspects of the present invention are essential. To solve some or all of the above-described problems or achieve some or all of the effects described herein, some of the components may be modified, deleted, replaced with new components, or some of the limitations may be removed, as appropriate. Furthermore, to solve some or all of the above-described problems or achieve some or all of the effects described herein, some or all of the technical features included in one aspect of the present invention described above may be combined with some or all of the technical features included in another aspect of the present invention described above to form an independent aspect of the present invention.

[0010] The present invention will be described in detail below with reference to the accompanying drawings, in which: FIG. 1 is a plan view showing a schematic configuration of a substrate processing system equipped with an embodiment of a substrate processing apparatus according to the present invention; FIG. 2 is a diagram showing the configuration of a main part of a substrate processing apparatus according to the present invention; and FIG. 3 is a flowchart showing a substrate processing method executed by the substrate processing apparatus shown in FIG. 2. The present invention will be described in detail with reference to the accompanying drawings;

[0011] 1 is a plan view showing the schematic configuration of a substrate processing system equipped with an embodiment of a substrate processing apparatus according to the present invention. This is not a view showing the external appearance of the substrate processing system 100, but rather a schematic view showing the internal structure of the substrate processing system 100 by excluding the outer wall panels and other components. The substrate processing system 100 is a single-wafer processing apparatus that is installed, for example, in a clean room and processes substrates S one by one.

[0012] The substrate processing system 100 includes a plurality of processing units (substrate processing apparatuses) 1, each of which mainly processes a substrate S. Although four processing units 1 are shown arranged horizontally in Fig. 1, the processing units 1 can also be stacked vertically in multiple stages. For example, when the processing units 1 are stacked in six stages, the substrate processing system 100 includes a total of 24 processing units 1.

[0013] As will be described later, each of the plurality of processing units 1 provided in the substrate processing system 100 receives a substrate S, performs chemical processing and rinsing processing on the upper surface of the substrate S, and then performs drying processing to dry the substrate S. In other words, the processing unit 1 corresponds to an example of a substrate processing apparatus 10 capable of performing an embodiment of the substrate processing method according to the present invention.

[0014] Here, the "substrate" in this embodiment can be any of various substrates, such as a semiconductor wafer, a glass substrate for a photomask, a glass substrate for a liquid crystal display, a glass substrate for a plasma display, a substrate for an FED (Field Emission Display), a substrate for an optical disk, a substrate for a magnetic disk, a substrate for a magneto-optical disk, etc. The following description will be given with reference to the drawings, taking as an example a substrate processing apparatus 10 used primarily for processing semiconductor wafers, but the apparatus can also be applied to processing the various substrates exemplified above.

[0015] As shown in FIG. 1 , the substrate processing system 100 has a substrate processing area 110 where substrates S are processed. An indexer unit 120 is provided adjacent to the substrate processing area 110. The indexer unit 120 has a container holder 121 that can hold a plurality of containers C for accommodating substrates S (e.g., FOUPs (Front Opening Unified Pods), SMIF (Standard Mechanical Interface) pods, and OCs (Open Cassettes) that accommodate a plurality of substrates S in a sealed state). The indexer unit 120 also has an indexer robot 122 that accesses the containers C held in the container holder 121 to remove unprocessed substrates S from the containers C and store processed substrates S into the containers C. Each container C accommodates a plurality of substrates S in a substantially horizontal position.

[0016] 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 S 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.

[0017] In the substrate processing area 110, a mounting table 112 is provided so that a substrate S from an indexer robot 122 can be placed thereon. A substrate transfer robot 111 is disposed approximately in the center of the substrate processing area 110 in a plan view. A plurality of processing units 1 (substrate processing apparatuses 10) are disposed surrounding the substrate transfer robot 111. Specifically, the processing units 1 are disposed facing the space in which the substrate transfer robot 111 is disposed. The substrate transfer robot 111 randomly accesses the mounting tables 112 for these processing units 1, and transfers the substrate S between the mounting tables 112. In this embodiment, these processing units 1 (substrate processing apparatuses 10) have the same functions. Therefore, parallel processing of multiple substrates S is possible. The mounting tables 112 are not necessarily required if the substrate transfer robot 111 can directly transfer the substrate S from the indexer robot 122 to the substrate transfer robot 111.

[0018] 2 is a diagram showing the configuration of the main components of a substrate processing apparatus according to the present invention. For ease of understanding, the dimensions and number of components are exaggerated or simplified in FIG. 2. As shown in FIG. 2, the substrate processing apparatus 10 includes a chamber 11, a spin chuck 12, a spin motor 13, a chemical nozzle 14, a nozzle moving unit 15, multiple guards 16, and a rinse nozzle 17.

[0019] Chamber 11 has a generally box-like shape and houses a spin chuck 12, a spin motor 13, a chemical nozzle 14, a nozzle moving unit 15, multiple guards 16, and a rinse nozzle 17. Chemical processing, rinsing processing, and drying processing are performed inside chamber 11.

[0020] The spin chuck 12 has a function of holding the substrate S and corresponds to an example of a "substrate holding portion" of the present invention. More specifically, the spin chuck 12 has a spin base 12a and multiple chuck members 12b. The spin base 12a is substantially disk-shaped and is disposed in a horizontal position. The multiple chuck members 12b are disposed on the upper surface of the spin base 12a. The multiple chuck members 12b hold the substrate S in a horizontal position. The spin chuck 12 may be, for example, a vacuum chuck or a Bernoulli chuck that utilizes the Bernoulli effect, and is not particularly limited.

[0021] The spin motor 13 is connected to the spin chuck 12, and rotates the spin chuck 12 holding the substrate S about the rotation axis AX in response to a rotation command from a control unit 18 that controls the entire apparatus, thereby causing the substrate S to also rotate about the rotation axis AX.

[0022] The chemical nozzle 14 is connected to a chemical supply unit (not shown) via a pipe P14. A valve V14 is inserted in this pipe P14. When an open command is given to this valve V14 from the control unit 18, the valve V14 opens and the chemical is supplied to the chemical nozzle 14. As a result, the chemical is supplied from the chemical nozzle 14 toward the upper surface of the substrate S held by the spin chuck 12. On the other hand, when the valve V14 is closed in response to a close command from the control unit 18, the supply of the chemical is stopped. In this way, the chemical nozzle 14 corresponds to an example of the "chemical supply unit" of the present invention.

[0023] Examples of chemical solutions include dilute hydrofluoric acid (DHF), hydrofluoric acid (HF), hydronitric acid (a mixture of hydrofluoric acid and nitric acid (HNO3)), buffered hydrofluoric acid (BHF), ammonium fluoride, HFEG (a mixture of hydrofluoric acid and ethylene glycol), phosphoric acid (H3PO4), sulfuric acid, acetic acid, nitric acid, hydrochloric acid, ammonia water, hydrogen peroxide water, organic acids (e.g., citric acid, oxalic acid), organic alkalis (e.g., TMAH: tetramethylammonium hydroxide), sulfuric acid hydrogen peroxide water mixture (SPM), ammonia hydrogen peroxide water mixture (SC1), hydrochloric acid hydrogen peroxide water mixture (SC2), surfactants, and corrosion inhibitors.

[0024] A nozzle moving unit 15 is connected to the chemical solution nozzle 14. The nozzle moving unit 15 has an arm 15a, a rotating shaft 15b, and a nozzle moving mechanism 15c. The arm 15a extends in a substantially horizontal direction. The chemical solution nozzle 14 is attached to the tip of the arm 15a, while the rear end of the arm 15a is connected to the rotating shaft 15b. The rotating shaft 15b extends in a substantially vertical direction and is rotatable about a rotation axis that also extends in a substantially vertical direction. The nozzle moving mechanism 15c is connected to the rotating shaft 15b. While the detailed configuration of the nozzle moving mechanism 15c is not shown, the nozzle moving mechanism 15c has an arm swing motor (not shown) that rotates the rotating shaft 15b about the rotation axis, and an arm lifting unit (not shown) that lifts and lowers the arm 15a by lifting and lowering the rotating shaft 15b that moves in a substantially vertical direction. Therefore, the arm swing motor and the arm lifting unit of the nozzle moving mechanism 15c are operated based on a movement command from the control unit 18, whereby the chemical nozzle 14 is moved and positioned between the processing position and the retracted position. Note that the processing position means a position above the substrate S, and the retracted position means a position radially outward of the substrate S.

[0025] The rinse liquid nozzle 17 is fixedly disposed with its outlet (not shown) facing the center of the upper surface of the substrate S held by the spin chuck 12. The rinse liquid nozzle 17 is connected to a DIW supply source (not shown) via a pipe P17. A valve V17 is also inserted in the pipe P17. When an open command is given to the valve V17 from the control unit 18, the valve V17 opens and DIW is supplied to the rinse liquid nozzle 14 as the rinse liquid. As a result, the rinse liquid is supplied from the rinse liquid nozzle 17 toward the upper surface of the substrate S held by the spin chuck 12. On the other hand, when the valve V17 is closed in response to a close command from the control unit 18, the supply of the rinse liquid is stopped. In this way, the rinse liquid nozzle 17 corresponds to an example of a "rinse liquid supply unit" in the present invention.

[0026] In addition to the above-mentioned DIW, the rinse liquid may include carbonated water, electrolytic ionized water, hydrogen water, ozone water, or diluted hydrochloric acid water (for example, about 10 ppm to 100 ppm).The particle concentration in the rinse liquid is lower than that in the chemical liquid, and a liquid equivalent to a so-called cleaning liquid is used as the rinse liquid.

[0027] The control unit 18 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 programs executed by the arithmetic unit. The control unit 18 controls each part of the substrate processing apparatus 10 in accordance with the programs, thereby performing the substrate processing described below.

[0028] Fig. 3 is a flowchart showing a substrate processing method executed by the substrate processing apparatus shown in Fig. 2. Fig. 4 is a diagram schematically showing major operations in the substrate processing method. In Fig. 4, the upper diagram shows the supply state of processing liquids (chemical liquid, rinse liquid) on the upper surface of the substrate, the middle and lower diagrams show cross-sectional structures, and the dashed lines indicate the order of operations. In Fig. 4(b), the middle diagram shows the first half of a first chemical processing run, while the lower diagram shows the first half of second and subsequent chemical processing runs, as described below.

[0029] An unprocessed substrate S is carried into the substrate processing apparatus 10 (processing unit 1) from the container C via the mounting table 112 by the indexer robot 122 and the substrate transport robot 111 (step S1). Here, the substrate S is carried in a horizontal position with one main surface (reference symbol Sa in FIG. 4 ) of the substrate S to be subjected to chemical processing facing upward, and is held by the spin chuck 12.

[0030] After the substrate transfer is completed and the substrate transfer robot 111 retreats from the substrate processing apparatus 10, the spin chuck 12 holding the substrate S is rotated at a first rotation speed (step S2). This first rotation speed can be set, for example, within a range of 50 rpm to 2500 rpm, and is set to 1000 rpm in this embodiment. Furthermore, supply of a rinse liquid to the upper surface Sa of the substrate S rotating at the first rotation speed is initiated (step S3). Specifically, DIW is ejected as the rinse liquid from the rinse liquid nozzle 17 toward the center of the upper surface of the substrate S. The rinse liquid supplied to the substrate S spreads radially from the center of the upper surface. As a result, as shown in FIG. 4(a), a rinse liquid film L1 having a thickness corresponding to the first rotation speed is formed on the upper surface Sa of the substrate S (rinse liquid film formation process). Here, detailed consideration of the structure of the rinse liquid film L1 based on boundary layer theory reveals that the rinse liquid film L1 has a viscous bottom layer L1a and a main region L1b. That is, as shown in the lower drawing of FIG. 4( a), the rinse liquid discharged onto the upper surface Sa of the rotating substrate S is divided into two layers: a viscous bottom layer L1a with almost no flow in the vertical direction, and a main layer L1b flowing in the radial direction of the substrate S.

[0031] In step S4, a chemical processing count value n, which indicates the number of chemical processing loops (described below), is set to an initial value of "1." Then, the process enters a chemical processing loop. In this chemical processing loop, chemical processing of the substrate S is repeatedly performed nmax times (e.g., six times) with the viscous bottom layer L2 and the main region L3 formed on the upper surface Sa of the substrate S by laminating them in this order (steps S51 to S59). When chemical processing begins, the chemical components in the chemical solution are diffused and transferred to the viscous bottom layer L1a composed of the rinse liquid, as described below, and the viscous bottom layer L1a contains the chemical components. Therefore, to distinguish between the viscous bottom layer before the start of chemical processing (= DIW only) and the viscous bottom layer after the start of chemical processing (= DIW + chemical components), the former is referred to as the "viscous bottom layer L1a" and the latter as the "viscous bottom layer L2."

[0032] In step S51, the supply of the rinse liquid to the upper surface Sa of the substrate S rotating at the first rotation speed is stopped. Thereafter, the rotation speed of the substrate S is changed from the first rotation speed to a second rotation speed (step S52). In this embodiment, the second rotation speed can be set within a range of, for example, 50 rpm to 2000 rpm, and in this embodiment, it is set to 500 rpm, which is lower than the first rotation speed.

[0033] Next, supply of the chemical solution to the upper surface Sa of the substrate S rotating at the second rotation speed is initiated (step S53). That is, after the chemical solution nozzle 14 moves to a processing position above the center of the upper surface of the substrate S rotating at the second rotation speed, a chemical solution such as hydrochloric acid (HCl) is ejected from the chemical solution nozzle 14. The chemical solution supplied to the substrate S spreads radially from the center of the upper surface. At this time, the above-described viscous bottom layer L2 and main flow region L3 are formed on the upper surface Sa of the substrate S, as shown in FIGS. 4(b) and 4(c). This is consistent with the boundary layer theory, which states that the liquid ejected onto the upper surface Sa of the rotating substrate S is separated into two layers: the viscous bottom layer L2, which has almost no flow in the vertical direction, and the main flow region L3, which flows radially of the substrate S, as shown in FIGS. 4(b) and 4(c). More specifically, in the first chemical processing, in the "chemical processing (first half)" (FIG. 4B) immediately after the start of chemical supply, the main stream region L1b of the rinse liquid film L1 is swept off the substrate by the chemical liquid, and the chemical liquid is replaced by the chemical liquid. This forms a main stream region L3 composed of the chemical liquid. However, the viscous bottom layer L1a on the upper surface Sa of the substrate S remains, and as the replacement progresses, the chemical liquid components in the chemical liquid are diffused and transferred from the main stream region L3. As a result, the viscous bottom layer L1a becomes a viscous bottom layer L2 in which the chemical liquid components are dispersed in the rinse liquid (DIW). Furthermore, in the second and subsequent chemical processing, the chemical processing is performed while the viscous bottom layer L2 remains, as shown in the lower drawing of FIG. 4B.

[0034] Although the thickness of this viscous bottom layer L2 depends on the discharge flow rate of the chemical solution from the chemical nozzle 14 and the rotation speed of the substrate S, it is on the order of several micrometers, and the rinse liquid continues to remain. This is also the case in the "chemical solution processing (latter half)" after time has passed. Meanwhile, as shown in FIG. 4( c), the mainstream region L3 is completely replaced by the chemical solution. Furthermore, during this replacement with the chemical solution, chemical components in the chemical solution reach the upper surface Sa of the substrate S from the mainstream region L3 via the viscous bottom layer L2. As a result, a chemical solution process such as an etching process is performed on the upper surface Sa of the substrate S.

[0035] Here, some of the particles PT contained in the chemical solution also diffuse from the main region L3 toward the viscous bottom layer L2, and then attempt to diffuse to the upper surface Sa of the substrate S. However, the diffusion coefficient of the particles PT is smaller than the diffusion coefficient of the chemical solution components. For example, a particle PT with a radius of 10 nm has a diffusion coefficient of 2.45×10 －７ cm ２ / sec, whereas that of the chemical component (HCl) is 3.7 × 10 －５ cm ２ Here, assuming that the thickness of the viscous bottom layer L2 is 10 μm, the time t(PT) required for the particle PT to reach the upper surface Sa of the substrate S through the viscous bottom layer L2 is given by t(PT)≈(thickness of the viscous bottom layer L2). ２ / (diffusion coefficient of particle PT)=3.25 sec. On the other hand, the time t(CC) required for the chemical component to reach the upper surface Sa of the substrate S through the viscous bottom layer L2 is: t(CC)≈(thickness of viscous bottom layer L2) ２ / (diffusion coefficient of chemical components) = 0.032 sec. Therefore, immediately after the start of chemical supply, the chemical components reach the upper surface Sa of the substrate S through the viscous sublayer L2 in a short time, and chemical processing effectively begins almost simultaneously with the start of chemical supply. Meanwhile, particles PT arrive at the upper surface Sa of the substrate S later than the chemical components. This technical discussion of particle adhesion to the upper surface of a substrate, combining boundary layer theory and an advection-diffusion model, is also described in the following paper: N. Handa and three others, "Experimental and Modeling Investigation of Re-Adhesion Mechanism of Detached Nanoparticles to Wafer Surface in Spin Rinse Process," [online], July 2, 2020, The Electrochemical Society, [searched May 13, 2024], Internet <URL: https: / / iopscience.iop.org / article / 10.1149 / 2162-8777 / ab9fe9 / meta>.

[0036] Based on this technical fact, the inventors of the present application have considered that chemical solution processing can be performed without causing particles PT to adhere to the upper surface Sa of the substrate S by stopping the chemical solution processing before the particles PT reach the upper surface Sa of the substrate S through the viscous bottom layer L2. As shown in FIG. 3 , it is determined whether a predetermined time (e.g., the time obtained by subtracting a few tenths of a second from the time t(PT)) has elapsed since the start of chemical solution supply (step S54). While the determination in step S54 is "NO," the chemical solution supply continues. Meanwhile, once the predetermined time has elapsed since the start of chemical solution supply, i.e., immediately before the time t(PT) has elapsed, the chemical solution supply is stopped (step S55).

[0037] Furthermore, in order to stop the chemical liquid processing, a rinse liquid is supplied to the upper surface Sa of the substrate S. More specifically, in step S56, it is determined whether the chemical liquid processing count value n has reached the maximum number of repetitions, i.e., nmax. Then, while the chemical liquid processing count value n has not reached nmax, steps S57 to S59 are executed, and then the process returns to step S51. Here, the case where the chemical liquid processing count value n is "1" is described, and the cases where the chemical liquid processing count value n is "2" to "nmax-1" are described later.

[0038] If the chemical solution processing count value n is "1," that is, if the chemical solution processing corresponds to the "first chemical solution process" of the present invention, which is executed following the rinse solution film forming process (step S3), the chemical solution processing count value n is incremented by "1" in step S57, and then a rinse solution film regeneration process (steps S58 and S59) is executed. This rinse solution film regeneration process (steps S58 and S59) corresponds to an example of the "rinse solution film regeneration process" of the present invention.

[0039] In this rinse liquid film regeneration process, the rotation speed of the substrate S is changed from the second rotation speed to the first rotation speed (step S58). In this embodiment, the rotation speed of the substrate S is increased from 500 rpm to 1000 rpm. Furthermore, supply of rinse liquid to the upper surface Sa of the substrate S rotating at the first rotation speed is initiated (step S59). This flushes the chemical liquid on the upper surface Sa of the substrate S away from the substrate S, eliminating the diffusion of chemical liquid components and particles PT from the main flow region L3, and regenerating a rinse liquid film L1 on the upper surface Sa of the substrate S, as shown in FIG. 4(d). Then, the process returns to step S51, where a second chemical liquid process is performed. That is, the rotation speed of the substrate S is decelerated from the first rotation speed to the second rotation speed (step S52), and supply of chemical liquid to the upper surface of the substrate S is initiated (step S53). This allows the chemical liquid process, which corresponds to an example of the "second chemical liquid process" of the present invention, to continue as long as the determination in step S54 is "NO." On the other hand, immediately before the time t(PT) elapses from the start of the chemical supply, the chemical supply is stopped (step S55). Such second chemical processing is repeated while the chemical processing count value n does not match "nmax" (determined "NO" in step S56). In other words, the rinse liquid film regeneration processing and the second chemical processing are repeated.

[0040] On the other hand, when the chemical liquid processing count value n matches "nmax" ("YES" is determined in step S56), that is, when one first chemical liquid processing and five second chemical liquid processings, a total of six chemical liquid processings, are completed, the chemical liquid processing loop is exited and step S6 is proceeded to.

[0041] At the time of exiting the chemical solution processing loop in this manner, as shown in Fig. 4(c), a viscous bottom layer L2 mainly composed of the rinse solution and a main layer region L3 mainly composed of the chemical solution are stacked in this order on the upper surface Sa of the substrate S. Therefore, in step S6, the rotation speed of the substrate S is changed to a rotation speed suitable for the rinse process, and the rinse solution is supplied to the upper surface Sa of the rotating substrate S. In this way, the rinse process is performed on the upper surface Sa of the substrate S (rinsing process). Subsequently, the substrate S is rotated at high speed to dry the substrate S (step S7).

[0042] When the series of substrate processing steps for the substrate S is completed in this manner, the substrate transport robot 111 enters the substrate processing apparatus 10, receives the processed substrate S from the spin chuck 12, and removes it (step S8). The substrate S is then stored in the container C via the mounting table 112 by the substrate transport robot 111 and the indexer robot 122.

[0043] As described above, the first embodiment utilizes the advection-diffusion characteristics of particles PT, where the diffusion coefficient of particles PT is smaller than that of the chemical components, and particles PT arrive at the upper surface Sa of the substrate S later than the chemical components. More specifically, a rinse liquid film regeneration process is performed for the first through (n-1) chemical processes, and a rinse process is performed for the final n-th chemical process. As a result, before particles PT diffuse from the mainstream region L3 into the viscous bottom layer L2 and reach the upper surface Sa of the substrate S, a rinse liquid is supplied to the upper surface Sa that has undergone the chemical process, washing away the chemical liquid that constitutes the mainstream region L3. This prevents particles PT from adhering to the upper surface Sa of the substrate S. As a result, impurities such as particles PT remaining on the upper surface Sa of the substrate S after chemical processing can be reduced.

[0044] In the above embodiment, the rotation speed of the substrate S during the chemical processing is slower than that during the rinse liquid film formation processing or the rinse liquid film regeneration processing. Therefore, the viscous bottom layer L2 during the chemical processing is thicker, and it is possible to prevent the particles PT from reaching the upper surface Sa of the substrate S. Moreover, it is possible to thin the main flow region L3 during the rinse liquid film regeneration processing or the rinse processing, thereby reducing the number of remaining particles PT.

[0045] 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 time required for one chemical treatment is shortened to the predetermined time set in step S54, so that the chemical treatment is performed multiple times. Here, if the desired chemical treatment results are obtained in the first chemical treatment (first chemical treatment), the subsequent rinse liquid film regeneration treatment and second chemical treatment may be omitted. In other words, the rinse treatment (step S6) may be performed following the first chemical treatment (first chemical treatment). Furthermore, the number of repetitions of the chemical treatment and rinse liquid film regeneration treatment are not limited to six and five, respectively, and may be arbitrary.

[0046] In the above embodiment, the chemical liquid processing is always performed at the second rotation speed, but the rotation speed may be changed depending on the chemical liquid processing count value n. The same applies to the rinse liquid film regeneration processing. That is, the rotation speed of the substrate S in the rinse liquid film regeneration processing may be changed depending on the chemical liquid processing count value n.

[0047] Furthermore, the types of rinse solutions and chemical solutions used in the processes of the above-described embodiments are merely examples, and various alternatives may be used as long as they are consistent with the technical concept of the present invention. While the invention has been described above with reference to specific examples, this description is not intended to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as other embodiments of the present invention, will become apparent to those skilled in the art upon reading the description of the invention. Therefore, the appended claims are intended to cover such modifications or embodiments within the true scope of the invention.

[0048] The present invention can be applied to general substrate processing techniques that perform chemical processing using a chemical liquid and rinsing processing using a rinse liquid on a substrate.

[0049] REFERENCE SIGNS LIST 10... Substrate processing apparatus 12... Spin chuck (substrate holding section) 14... Chemical liquid nozzle (chemical liquid supply section) 17... Rinse liquid nozzle (rinse liquid supply section) L1... Rinse liquid film L1a, L2... Viscous bottom layer L3... Main stream region PT... Particles (impurities) S... Substrate Sa... Upper surface (one main surface of the substrate)

Claims

1. A substrate processing method comprising: a rinse liquid film forming step of supplying a rinse liquid to one main surface of the substrate to form a rinse liquid film on the one main surface of the substrate; a first chemical liquid process of supplying a chemical liquid containing a chemical liquid component toward the one main surface of the substrate having the rinse liquid film formed in the rinse liquid film forming step, thereby forming a mainstream region on the one main surface of the substrate where the chemical liquid flows outward from the substrate on a viscous bottom layer composed of the rinse liquid, and processing the one main surface of the substrate with the chemical liquid component that diffuses from the mainstream region into the viscous bottom layer and reaches the one main surface of the substrate; and a rinse step of supplying the rinse liquid to rinse the entire one main surface of the substrate before impurities contained in the chemical liquid and having a diffusion coefficient smaller than that of the chemical liquid component diffuse from the mainstream region into the viscous bottom layer and reach the one main surface of the substrate.

2. A substrate processing method according to claim 1, wherein the viscous bottom layer is formed by supplying the rinse liquid to one main surface of the substrate in the rinse liquid film forming step.

3. A substrate processing method according to claim 1, wherein the rinse liquid film forming step and the first chemical liquid step are alternately repeated multiple times.

4. A substrate processing method according to any one of claims 1 to 3, wherein the rinse liquid film forming step is a step of supplying the rinse liquid while rotating the substrate within a range of 50 rpm to 2500 rpm, and the first chemical liquid step is a step of supplying the rinse liquid while rotating the substrate within a range of 50 rpm to 2000 rpm.

5. A substrate processing method according to claim 1, comprising: a rinse liquid film regeneration process in which the rinse liquid is supplied to one main surface of the substrate before the impurities diffuse from the mainstream region into the viscous bottom layer and reach one main surface of the substrate, thereby rinsing at least the mainstream region and regenerating a rinse liquid film on the one main surface of the substrate; and a second chemical liquid process in which the chemical liquid is supplied toward the one main surface of the substrate on which the rinse liquid film has been formed in the rinse liquid film regeneration process, thereby forming a stack of the viscous bottom layer and the mainstream region, and treating the one main surface with the chemical liquid components that diffuse from the mainstream region into the viscous bottom layer and reach the one main surface of the substrate, wherein the rinse liquid film regeneration process and the second chemical liquid process are carried out between the first chemical liquid process and the rinse process.

6. A substrate processing method according to claim 5, wherein the rinse liquid film regeneration step and the second chemical liquid step are repeated multiple times.

7. A substrate processing method according to claim 5 or 6, wherein the rinse liquid film forming step and the rinse liquid film regenerating step are steps of supplying the rinse liquid while rotating the substrate within a range of 50 rpm to 2500 rpm, and the first chemical liquid step and the second chemical liquid step are steps of supplying the rinse liquid while rotating the substrate within a range of 50 rpm to 2000 rpm.

8. A substrate processing apparatus comprising: a substrate holding unit that holds a substrate with one main surface of the substrate facing upward; a rinse liquid supply unit that supplies a rinse liquid to one main surface of the substrate held by the substrate holding unit; a chemical liquid supply unit that supplies a chemical liquid to one main surface of the substrate held by the substrate holding unit; and a control unit that controls the rinse liquid supply unit and the chemical liquid supply unit so as to perform the substrate processing method defined in claim 1, 2, 3, 5 or 6.

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