SUBSTRATE PROCESSING METHOD AND SUBSTRATE PROCESSING APPARATUS

Abstract

To reduce usage of a low surface tension liquid while preventing particles from being generated.SOLUTION: A substrate processing method includes: a first processing step of supplying a first process liquid to a rotating substrate surface and coating the substrate surface with a liquid film of the first process liquid; and a second processing step of supplying a second process liquid of which the surface tension is smaller than that of the first process liquid, to the substrate surface after the first processing step and replacing the first process liquid on the substrate surface with the second process liquid. The second process step includes: a first phase of simultaneously supplying the first process liquid in addition to the second process liquid to the substrate surface; and a second phase of supplying the second process liquid to a central part of the substrate surface without supplying the first process liquid after the first phase. During at least a first period in the first phase, while maintaining a condition that a first radial distance from a substrate rotation center on the substrate surface to a liquid landing position of the first process liquid is larger than a second radial direction that is a distance to a liquid landing position of the second process liquid, both the first and second radial distances are enlarged.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus. [Background technology]

[0002] In the manufacture of semiconductor devices, a substrate is held in a horizontal position by a spin chuck and rotated about a vertical axis, and various processing liquids are supplied to the substrate to perform a predetermined liquid processing. Patent Document 1 describes the following regarding the transition from the rinsing process to the replacement process. In the latter half of the rinsing process, in addition to supplying the rinsing liquid to the center of the substrate, the rinsing liquid is also supplied to the outer periphery of the substrate. Thereafter, while continuing to supply the rinsing liquid to the outer periphery of the substrate, the supply of the rinsing liquid to the center of the substrate is stopped, and at the same time, IPA (isopropyl alcohol) is supplied to the center of the substrate. Thereafter, while continuing to supply IPA to the center of the substrate, the supply of the rinsing liquid to the outer periphery of the substrate is stopped. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6118758 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique that can reduce the amount of low surface tension liquid used while preventing the occurrence of defects such as particles. [Means for solving the problem]

[0005] In one embodiment of the present disclosure, a method includes a first processing step of supplying a first processing liquid onto a surface of a rotating substrate to cover the surface of the substrate with a liquid film of the first processing liquid, and a second processing step of supplying a second processing liquid having a surface tension smaller than that of the first processing liquid onto the surface of the rotating substrate after the first processing step, and replacing the first processing liquid on the substrate with the second processing liquid to cover the surface of the substrate with a liquid film of the second processing liquid, wherein the second processing step is The present invention provides a substrate processing method including a first step of simultaneously supplying the first processing liquid in addition to the second processing liquid to the surface of the rotating substrate, and a second step of supplying the second processing liquid to a center of the surface of the rotating substrate after the first step without supplying the first processing liquid, wherein, during at least a first period of the first step, a first radial distance, which is the distance from the center of rotation of the substrate to a landing point of the first processing liquid on the surface of the substrate, is increased while maintaining a condition that the first radial distance is greater than a second radial distance, which is the distance from the center of rotation of the substrate to a landing point of the second processing liquid. Effect of the Invention

[0006] According to the present disclosure, it is possible to reduce the amount of low surface tension liquid used while preventing the occurrence of defects such as particles. [Brief description of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view of a substrate processing apparatus according to an embodiment of the present invention; [Diagram 2] 2 is a vertical sectional view showing an example of a processing unit included in the substrate processing apparatus of FIG. 1. [Diagram 3] 3 is a schematic plan view showing some parts such as a liquid receiving cup, a nozzle, and a nozzle arm taken out from the processing unit of FIG. 2. [Figure 4] 11 is a schematic side view for explaining an example of the operation of the drying liquid nozzle and the rinsing nozzle in the IPA replacement step. FIG. [Diagram 5] 11 is a graph illustrating an example of an operation of a processing unit in an IPA replacement step. [Figure 6] 13 is a schematic side view for explaining another example of the operation of the drying liquid nozzle and the rinsing nozzle in the IPA replacement step. FIG. [Figure 7] 4 is a schematic vertical cross-sectional view showing some parts of an embodiment in which an auxiliary nozzle is added to the processing unit of FIGS. 2 and 3. FIG. [Figure 8] 8 is a schematic plan view showing some parts of the processing unit shown in FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An embodiment of a substrate processing apparatus will be described with reference to the accompanying drawings.

[0009] 1 is a diagram showing a schematic configuration of a substrate processing system according to the present embodiment. In the following, to clarify the positional relationship, an X-axis, a Y-axis, and a Z-axis that are perpendicular to each other are defined, and the positive direction of the Z-axis is defined as the vertical upward direction.

[0010] 1, the substrate processing system 1 includes a loading / unloading station 2 and a processing station 3. The loading / unloading station 2 and the processing station 3 are provided adjacent to each other.

[0011] The carry-in / out station 2 includes a carrier placement section 11 and a transport section 12. On the carrier placement section 11, a plurality of carriers C are placed, each of which accommodates a plurality of substrates W, in this embodiment, semiconductor wafers, in a horizontal state.

[0012] The transport section 12 is provided adjacent to the carrier placement section 11, and includes therein a substrate transport device 13 and a transfer section 14. The substrate transport device 13 includes a wafer holding mechanism that holds the substrate W. The substrate transport device 13 is capable of moving in the horizontal and vertical directions and rotating about a vertical axis, and transports the substrate W between the carrier C and the transfer section 14 using the wafer holding mechanism.

[0013] The processing station 3 is provided adjacent to the transport section 12. The processing station 3 includes a transport section 15 and a plurality of processing units 16. The plurality of processing units 16 are provided side by side on both sides of the transport section 15.

[0014] The transfer section 15 includes a substrate transfer device 17 therein. The substrate transfer device 17 includes a wafer holding mechanism that holds the substrate W. The substrate transfer device 17 is capable of moving in the horizontal and vertical directions and rotating about a vertical axis, and transfers the substrate W between the delivery section 14 and the processing unit 16 using the wafer holding mechanism.

[0015] The processing unit 16 performs a predetermined substrate processing on the substrate W transported by the substrate transport device 17 .

[0016] The substrate processing system 1 also includes a control device 4. The control device 4 is, for example, a computer, and includes a control unit 18 and a storage unit 19. The storage unit 19 stores programs for controlling various processes executed in the substrate processing system 1. The control unit 18 controls the operation of the substrate processing system 1 by reading out and executing the programs stored in the storage unit 19.

[0017] Such a program may be recorded in a computer-readable storage medium and installed from that storage medium into the storage unit 19 of the control device 4. Examples of computer-readable storage media include a hard disk (HD), a flexible disk (FD), a compact disk (CD), a magnet optical disk (MO), and a memory card.

[0018] In the substrate processing system 1 configured as described above, first, the substrate transport device 13 in the loading / unloading station 2 takes out the substrate W from the carrier C placed on the carrier placement part 11, and places the taken-out substrate W on the transfer part 14. The substrate W placed on the transfer part 14 is taken out of the transfer part 14 by the substrate transport device 17 in the processing station 3, and is carried into the processing unit 16.

[0019] The substrate W carried into the processing unit 16 is processed by the processing unit 16, and then carried out of the processing unit 16 by the substrate transport device 17 and placed on the transfer section 14. Then, the processed substrate W placed on the transfer section 14 is returned by the substrate transport device 13 to the carrier C of the carrier placement section 11.

[0020] Next, the configuration of the processing unit 16 will be described with reference to FIG.

[0021] As shown in FIG. 2, the processing unit 16 includes a chamber 20, a substrate holding and rotating mechanism 30, a processing fluid supply part 40, and a liquid receiving cup 60.

[0022] The chamber 20 accommodates a substrate holding and rotating mechanism 30, a processing fluid supply unit 40, and a liquid receiving cup 60. An FFU (Fan Filter Unit) 21 is provided on the ceiling of the chamber 20. The FFU 21 forms a downflow within the chamber 20.

[0023] The substrate holding and rotating mechanism 30 has a substrate holding part (chuck part) 31 that holds the substrate W in a horizontal position, and a rotation drive part 32 that rotates the substrate holding part 31 holding the substrate W about a vertical axis. The substrate holding part 31 may be of a type called a mechanical chuck that holds the peripheral part of the substrate W with gripping claws, or may be of a type called a vacuum chuck that vacuum-sucks the back surface of the substrate W. The rotation drive part 32 has an electric motor as a driving force generation source, and can rotate the substrate holding part 31 at any speed.

[0024] The processing fluid supply unit 40 has a plurality of processing fluid nozzles and one or more nozzle arms. In the illustrated embodiment, the plurality of processing fluid nozzles include at least a chemical / rinsing nozzle 41, a drying liquid nozzle 42, a rinsing nozzle 43, and a gas nozzle 44. The chemical / rinsing liquid nozzle 41 selectively discharges DHF (dilute hydrofluoric acid) which is an acidic chemical liquid and DIW (pure water) as a rinsing liquid. The drying liquid nozzle 42 discharges a liquid, for example, IPA (isopropyl alcohol), which has a lower surface tension than the rinsing liquid, is preferably more volatile than the rinsing liquid, and preferably has a property (for example, compatibility) that allows it to be easily replaced with the rinsing liquid. The rinsing nozzle 43 discharges DIW as the rinsing liquid. The gas nozzle 44 discharges a drying gas such as a gas with low humidity and low oxygen concentration, for example, nitrogen gas. The rinsing liquid may be functional water obtained by dissolving a small amount of electrolyte component in DIW, in addition to DIW.

[0025] A processing fluid is supplied to each processing fluid nozzle via a processing fluid supply mechanism (schematically shown by a double circle in FIG. 2). As is widely known in the art, the processing fluid supply mechanism can be composed of a processing fluid supply source such as a tank or a factory utility, a supply line that supplies processing fluid from the processing fluid supply source to the processing fluid nozzle, and flow rate adjustment devices such as a flow meter, an on-off valve, and a flow control valve, as well as auxiliary devices such as a filter and a heater, which are provided on the supply line. Each processing fluid supply mechanism can control on / off of the discharge of processing fluid from the corresponding processing fluid nozzle, and the discharge flow rate of the processing fluid from the corresponding processing fluid nozzle.

[0026] A chemical liquid supply mechanism and a rinsing liquid supply mechanism serving as a processing fluid supply mechanism are connected to the chemical liquid / rinsing nozzle 41, thereby enabling the chemical liquid (DHF) or the rinsing liquid (DIW) to be selectively discharged from the chemical liquid / rinsing nozzle 41.

[0027] In the illustrated embodiment, the processing fluid supply unit 40 has two nozzle arms, i.e., a first nozzle arm 51 and a second nozzle arm 52, as the one or more nozzle arms described above. In the illustrated embodiment, the first nozzle arm 51 and the second nozzle arm 52 are swung about a pivot axis extending in the vertical direction by arm drive mechanisms 53, 54 provided at the base end of each. The chemical / rinse nozzle 41 and the drying liquid nozzle 42 are supported at the tip of the first nozzle arm 51. The rinse nozzle 43 and the gas nozzle 44 are supported at the tip of the second arm 52.

[0028] In the illustrated embodiment, the first nozzle arm 51 and the second nozzle arm 52 are installed so that their respective tips (i.e., the processing fluid nozzles (41-44) supported thereon) can move along substantially the same arc-shaped trajectory in a plan view. In the illustrated embodiment, the trajectories of the tips of both nozzle arms 51, 52 pass directly above the center of rotation Wc of the substrate W. In the illustrated embodiment, the positions of the rotation centers (positions of 53, 54) of both nozzle arms 51, 52 are slightly different, so the movement trajectories of the tips of both nozzle arms 51, 52 do not completely match, but may be considered to be substantially the same. Note that the arrangement of the first nozzle arm 51 and the second nozzle arm 52 in FIG. 2 does not match the arrangement in FIG. 3, but this is because importance is attached to the ease of viewing the drawing, and the arrangement in FIG. 3 is correct.

[0029] The processing unit 16 may further include another nozzle arm. The nozzle arm is not limited to a swivel arm type as shown in the figure, but may be a linear motion type that moves in a translational manner along a guide rail. In addition, when two swivel type nozzle arms are provided, both nozzle arms may be provided so that the tips of both nozzle arms describe a moving locus that is point symmetrical with respect to the center of rotation Wc of the substrate W in a plan view.

[0030] The liquid receiving cup 60 is provided so as to surround the substrate holding part 31, and collects the processing liquid scattered from the rotating substrate W. The processing liquid collected by the liquid receiving cup 60 is discharged to the outside of the processing unit 16 from a drainage port 61 provided in the bottom of the liquid receiving cup 60. An exhaust port 62 is also provided in the bottom of the liquid receiving cup 60, and the inside of the liquid receiving cup 60 is suctioned through the exhaust port 62.

[0031] Next, a series of steps of liquid processing performed by processing unit 16 will be described. The following steps are performed under the control of controller 4. In one embodiment, a process recipe and a control program are stored in memory 19 of controller 4, and controller 4 executes the control program to control the operation of each component of processing unit 16, thereby performing the steps described below.

[0032] In the illustrated embodiment, the nozzles (41-43) for discharging the processing liquid are attached to the arms 51, 52 so as to discharge the processing liquid directly downward. Therefore, in the following description, the position of each nozzle (41-43) itself (specifically, the position of the nozzle discharge port) and the position of the "landing point" of the processing liquid discharged from each nozzle (41-43) on the surface of the substrate W mean the same thing. Note that the nozzles for supplying the processing gas spray the processing gas obliquely downward (towards the periphery of the substrate W).

[0033] In the following description, the term "liquid landing point" refers to the intersection point between the center (central axis of the cylinder) of the liquid (liquid column) discharged in a cylindrical shape from the nozzle (41-43) and the surface of the substrate W. When the nozzle discharges the liquid straight down, the position of the nozzle (strictly speaking, the position of the central axis of the nozzle discharge port) and the position of the liquid landing point are the same (with respect to the horizontal position excluding the height direction position). In addition, the liquid discharged in a cylindrical shape from the nozzle spreads on the surface of the substrate W due to the force of collision at the moment when the liquid lands on the surface of the substrate W. Therefore, even if the liquid landing point of the liquid discharged from the nozzle is slightly off to the outside in the radial direction from the rotation center Wc of the substrate W, the liquid spreads due to the force of collision as described above and covers the rotation center Wc of the substrate W. In other words, in this case as well, the liquid discharged from the nozzle is supplied to the center of the substrate (the region near the rotation center Wc including the rotation center Wc of the substrate).

[0034] For ease of explanation, the surface of the substrate W is divided into two regions I and II in order to define the position of the nozzle itself and the position of the liquid landing point. As shown in FIG. 3, in a plan view, the region on the first nozzle arm 51 side of the normal line N at the rotation center Wc of the nozzle movement trajectory (indicated by two arc-shaped arrows) is defined as region I, and the region on the second nozzle arm 52 side of the normal line N is defined as region II. The nozzle position (position of the liquid landing point) is expressed by the R value. When the nozzle position (position of the liquid landing point) is within region I, the R value is expressed as the radial distance of the nozzle position (position of the liquid landing point) from the rotation center Wc of the substrate W × (+1). When the nozzle position (position of the liquid landing point) is within region II, the R value is expressed as the radial distance of the nozzle position (position of the liquid landing point) from the rotation center Wc of the substrate W × (-1).

[0035] From the start to the end of the series of steps described below, the substrate W continues to rotate without stopping. The rotation speed of the substrate W is changed as necessary.

[0036] [Chemical treatment process] First, DHF is discharged as a chemical liquid at a predetermined flow rate from the chemical / rinse nozzle 41 supported by the first nozzle arm 51 so that the liquid lands on the center of rotation Wc (R=0 mm) of the rotating substrate W. The DHF that lands on the center of the substrate W spreads and flows toward the periphery of the substrate W due to centrifugal force, and the entire surface of the substrate W is covered with a liquid film of DHF. By continuing this state for a predetermined time, the surface of the substrate W is subjected to chemical liquid processing.

[0037] [Rinse process] Next, the liquid discharged from the chemical / rinse nozzle 41 is switched from DHF to DIW. That is, DIW as a rinsing liquid is discharged from the chemical / rinse nozzle 41 at a predetermined flow rate so that the DIW lands on the center of the substrate W.

[0038] Next, while maintaining the landing point of DHF from chemical / rinse nozzle 41 at the center of rotation Wc (R = 0 mm), DIW is also ejected from rinse nozzle 43 supported by second nozzle arm 52 so that the DIW lands at a position slightly away from the center of rotation Wc (for example, R = -42 mm).

[0039] While continuing to eject DIW from chemical / rinse nozzle 41 and rinse nozzle 43, first nozzle arm 51 and second nozzle arm 52 are moved simultaneously to move the landing point of DIW from chemical / rinse nozzle 41 to a position slightly away from the rotation center Wc (for example, R=+42 mm) and move the landing point of DIW from rinse nozzle 43 to the rotation center Wc (R=0 mm). Then, ejection of DIW from chemical / rinse nozzle 41 is stopped.

[0040] It is preferable that the discharge flow rate per nozzle while both the chemical / rinse nozzle 41 and the rinse nozzle 43 are simultaneously discharging DIW is smaller than the discharge flow rate per nozzle while only one of the chemical / rinse nozzle 41 and the rinse nozzle 43 is discharging DIW. If the two nozzles are placed close to each other and liquid is simultaneously supplied to the surface of the substrate W at a large flow rate, liquid splashes may occur due to interference between the liquids.

[0041] In the above-mentioned rinsing step, the DIW that has landed at (or near) the center of the substrate W spreads and flows toward the periphery of the substrate W due to centrifugal force, and the entire surface of the substrate W is covered with a liquid film of DIW. Accordingly, the DHF and reaction products remaining on the surface of the substrate W are washed away by the DIW.

[0042] In the above embodiment, the nozzle that discharges the rinsing liquid is changed from the chemical / rinsing nozzle 41 to the rinsing nozzle 43 during the rinsing step, but the reason for doing so is that the chemical / rinsing nozzle 41 and the drying liquid nozzle 42 are supported on the same nozzle arm. For example, if the drying liquid nozzle 42 is supported on a different nozzle arm (e.g., a third nozzle arm), the above change operation does not need to be performed, and the nozzle that discharges the rinsing liquid may be only the chemical / rinsing nozzle 41.

[0043] [IPA replacement process] Next, a description will be given of an IPA replacement process for replacing the DIW on the surface of the substrate W (including inside the recesses of the pattern) with IPA. In the description of the IPA replacement process, reference will also be made to FIGS.

[0044] Fig. 4 shows the movement of the drying liquid nozzle 42 (held by the first nozzle arm 51) and the rinse nozzle 43 (held by the second nozzle arm 52) as viewed from the direction of arrow A in Fig. 3. The left side of Fig. 4 corresponds to region I (R value is positive), and the right side of Fig. 4 corresponds to region II (R value is negative). In Fig. 4, nozzles other than nozzles 42 and 43 are not shown to simplify the drawing.

[0045] In the graph of Fig. 5, the upper part shows the rotation speed of the substrate W, the middle part shows the discharge flow rate of IPA from the drying liquid nozzle 42 (thin solid line) and the discharge flow rate of DIW from the rinse nozzle 43 (thick solid line), and the lower part shows the distance from the rotation center Wc to the landing point of IPA from the drying liquid nozzle 42 on the surface of the substrate W (thin solid line) and the distance from the rotation center Wc to the landing point of DIW from the rinse nozzle 43 (thick solid line). The absolute value of the R value described above is displayed in the lower part (it does not matter whether the landing point of the liquid from the nozzles 42, 43 is in region I or II). In the graph of Fig. 5, the horizontal axis shows the elapsed time calculated from the start of the IPA replacement process, and the unit is "seconds".

[0046] When the rinse nozzle 43 discharges DIW toward the rotation center Wc of the substrate W for a predetermined time and the rinse step is completed, the drying liquid nozzle 42 is brought close to the rinse nozzle 43 while maintaining the position of the rinse nozzle 43 and the discharge state of DIW. At this time, the R value of the drying liquid nozzle 42 is, for example, -42 mm, and the R value of the rinse nozzle 43 is 0 mm. Note that from the latter part of the rinse step until this point, DIW is continuously discharged from the rinse nozzle 43 at a relatively large discharge flow rate (for example, 1500 ml / min) (see (A) of FIG. 4 and the point at 0 seconds elapsed in FIG. 5). While DIW is being discharged from the rinse nozzle 43 in the latter part of the rinse step, the drying liquid nozzle 42 may be brought close to the rinse nozzle 43.

[0047] Next, the drying liquid nozzle 42 and the rinsing nozzle 43 are moved simultaneously (preferably at the same moving speed, for example, about 22 mm / sec) in the negative direction, so that the drying liquid nozzle 42 is moved to directly above the center of rotation of the substrate W (a position where the R value is 0 mm), and the rinsing nozzle 43 is moved to a position slightly away from the center of rotation of the substrate W (for example, a position where the R value is -43 mm) (see Figures 4B and 4C and the period from 0 seconds to 2 seconds elapsed in Figure 5).

[0048] During this movement process, when the distance from the center of rotation Wc of the landing point of the IPA from the drying liquid nozzle 42 and the distance from the center of rotation Wc of the landing point of the DIW from the rinse nozzle 43 become approximately equal (for example, when the R value of the landing point of the IPA becomes +22 mm and the R value of the landing point of the DIW becomes -20 mm), the DIW discharge flow rate from the rinse nozzle 43 is reduced from the first DIW discharge flow rate (for example, 1500 ml / min) to a smaller second DIW discharge flow rate (for example, 1000 ml / min), and the drying liquid nozzle 42 starts discharging IPA at the first IPA discharge flow rate (for example, 30 ml / min) (see Figure 4B and the 1 second elapsed time in Figure 5).

[0049] That is, at the point when the elapsed time is 1 second, the first stage of the IPA replacement process is started in which both IPA and DIW are supplied to the substrate W. At this time, by starting to eject IPA before the drying liquid nozzle 42 reaches directly above the rotation center Wc of the substrate, it is possible to more reliably prevent the liquid from disappearing from the region near the rotation center W of the substrate W. This effect is greater than that in the case where ejection of IPA is not started until the drying liquid nozzle 42 reaches directly above the rotation center Wc of the substrate after the rinse nozzle 43 moves out of the position directly above the rotation center Wc of the substrate.

[0050] When the landing point of the IPA from the drying liquid nozzle 42 coincides with the rotation center Wc and the landing point of the DIW from the rinse nozzle 43 reaches a position slightly away from the rotation center Wc (for example, a position where the R value is −42 mm), the rinse nozzle 43 continues to move in the negative direction, while the moving direction of the drying liquid nozzle 42 is reversed and moved in the positive direction (see FIG. 4C and the point at the time when the elapsed time is 2 seconds in FIG. 5). That is, the rinse nozzle 43 and the drying liquid nozzle 42 are moved in the opposite directions. Also, at the same time or almost at the same time when the drying liquid nozzle 42 starts to move in the positive direction from the rotation center Wc toward the periphery, the rotation speed of the substrate W is reduced (1000 rpm→700 rpm). By reducing the rotation speed of the substrate W, the timing when a dry region starts to be formed near the rotation center Wc on the surface of the substrate W can be delayed.

[0051] At this time, the rinse nozzle 43 and the drying liquid nozzle 42 are moved in opposite directions so as to constantly satisfy the condition that the distance (absolute value of R) from the center of rotation Wc of the landing point of DIW from the rinse nozzle 43 is greater than the distance (absolute value of R) from the center of rotation Wc of the landing point of IPA from the drying liquid nozzle 42 (see (C) to (E) of Figures 4 and the period from 2 seconds to 5.3 seconds in the lower part of Figure 5).

[0052] In addition, at this time, as shown in the lower part of the graph in FIG. 4, the movement speed of the rinse nozzle 43 and the movement speed of the drying liquid nozzle 42 may be maintained the same so that the difference between the absolute value of the R value of the DIW landing point and the absolute value of the R value of the IPA landing point is maintained constant. The movement speed of the rinse nozzle 43 and the drying liquid nozzle 42 at this time can be set in the range of, for example, 20 to 50 mm / sec. In addition, the difference between the absolute value of the R value of the DIW landing point and the absolute value of the R value of the IPA landing point is preferably within the range of about 40 mm to 90 mm, depending on the discharge flow rates of the DIW and IPA. If the difference is too large, the liquid splash prevention effect described later may be reduced. In addition, if the difference is too small, the DIW after landing and the IPA after landing may collide with each other, causing liquid splashing.

[0053] When the rinse nozzle 43 reaches a position near the periphery of the substrate W (for example, a position where the R value of the landing point of the DIW is −140 mm) (see FIG. 4E), the movement of the rinse nozzle 43 is stopped, and the discharge of DIW from the rinse nozzle 43 is also stopped. At the same time or almost at the same time, the drying liquid nozzle 42 is moved to a position directly above the center of rotation Wc (R=0 mm) while continuing to discharge IPA from the drying liquid nozzle 42. In addition, at the same time or almost at the same time when the drying liquid nozzle 42 reaches a position directly above the center of rotation Wc, the discharge flow rate of IPA from the drying liquid nozzle 42 is increased to a second discharge flow rate (for example, 75 ml / min) (see FIGS. 4E to 4F and after the elapsed time of 5.3 seconds in FIG. 5).

[0054] That is, at the point of time when the elapsed time is 5.3 seconds, the first stage of the IPA replacement process in which both IPA and DIW are supplied to the substrate W ends, and the second stage of the IPA replacement process in which only IPA is supplied to the substrate W begins. Thereafter, the supply of IPA to the rotation center Wc of the substrate continues for a predetermined time, thereby completing the second stage of the IPA replacement process.

[0055] In the first stage of the IPA replacement process, a liquid film of IPA is formed in the central region of the substrate W, and a liquid film of the mixed liquid of IPA and DIW is formed in the peripheral (outer) region. Strictly speaking, in the state of FIG. 4B (at the time when 1 second has elapsed), the rotation center Wc of the substrate W is covered only with DIW that has landed slightly radially outward from the rotation center Wc and spread to the rotation center Wc by the momentum of the landing, and the region radially outward from the landing point of IPA is covered with the mixed liquid of IPA and DIW. Then, as shown in FIG. 4C to FIG. 4E, the region where the inner liquid film of IPA exists spreads over time, and the region where the outer liquid film of the mixed liquid exists narrows. Then, in the second stage of the IPA replacement process, the entire surface of the substrate W becomes covered with the liquid film of IPA.

[0056] That is, in the IPA replacement step, looking at each part of the surface of the substrate W, the DIW at that part is first replaced by the mixture of IPA and DIW, and then replaced by IPA.

[0057] In the IPA replacement process, a dry area must not be formed on the surface of the substrate W near the rotation center Wc until the landing point of the IPA from the drying liquid nozzle 42 leaves the rotation center Wc, moves toward the periphery of the substrate W, and returns to the rotation center Wc. This is because an unintended dry area may cause defects such as particles. In actual operation of the apparatus, under the processing conditions exemplified in FIG. 4 and FIG. 5, it has been confirmed that even if the surface of the substrate W is hydrophobic, no dry area is formed on the surface of the substrate W near the rotation center Wc and processing can be performed without problems. Note that, if drying occurs near the rotation center Wc, it can be dealt with by appropriately combining the following: increasing the discharge flow rate of the IPA from the drying liquid nozzle 42, decreasing the rotation speed of the substrate W, and shortening the time from when the landing point of the IPA leaves the rotation center Wc until it returns to the rotation center Wc.

[0058] In the above-mentioned IPA replacement process, the landing points of the rinse nozzle 43 and the drying liquid nozzle 42 are moved radially outward so as to always satisfy the condition that the distance from the rotation center Wc of the landing point of the DIW from the rinse nozzle 43 is greater than the distance from the rotation center Wc of the landing point of the IPA from the drying liquid nozzle 42. This makes it possible to reduce the consumption of IPA, and to prevent or significantly suppress liquid splashing even if the surface of the substrate W is hydrophobic. If liquid splashing occurs, there is a risk that the substrate W will be contaminated due to droplets that bounce off the liquid receiving cup adhering to the substrate W, or minute droplets floating around the substrate W adhering to the substrate W, etc.

[0059] The reason why the above effect is obtained will be explained below. Suppose that, in a state where DIW is being supplied from the rinse nozzle toward the center of the substrate, the discharge of DIW from the rinse nozzle is stopped, and immediately thereafter, the discharge of IPA from the drying liquid nozzle toward the center of the substrate is started. In this case, the liquid film of DIW may break at the peripheral portion of the substrate W before the liquid film of IPA spreads to the peripheral portion of the substrate, and the peripheral portion may be exposed to air. This phenomenon is particularly likely to occur when the surface of the substrate W is hydrophobic. The occurrence of the above phenomenon can be suppressed by increasing the discharge flow rate of IPA from the drying liquid nozzle to quickly spread the liquid film of IPA over the entire surface of the substrate. However, the amount of expensive IPA used increases.

[0060] While continuing to spray IPA from the drying liquid nozzle toward the center of the substrate, the landing point of the DIW sprayed from the rinse nozzle is gradually moved closer to the edge of the substrate, thereby preventing the liquid film from running out in the outer regions of the substrate and spreading the area covered by the IPA liquid film toward the edge of the substrate.

[0061] It was confirmed by the inventor's experiments that it is necessary to maintain the IPA discharge flow rate relatively high when the landing point of the IPA discharged from the drying liquid nozzle is kept at the center of rotation of the substrate and the landing point of the DIW discharged from the rinse nozzle is gradually moved closer to the periphery of the substrate W. Specifically, in one experimental example, it was confirmed that when the IPA discharge flow rate is reduced below a certain threshold value (50 ml / min), splashing occurs when the landing point of the DIW is located outside a certain radial position (a position about 85 mm away from the center of rotation).

[0062] Since the surface tension of IPA is significantly lower than that of DIW, and IPA and DIW are highly compatible, the surface of a substrate on which a sufficiently thick IPA film exists can be considered to be equivalent to a highly hydrophilic surface. The thickness of the film formed on the substrate by IPA discharged from the drying liquid nozzle and landing at the center of rotation of the substrate becomes thinner as it moves radially outward. When DIW discharged from the rinse nozzle at a relatively large discharge rate collides with a thin IPA film, the IPA film is destroyed near the collision point, and the DIW directly collides with the hydrophobic surface, causing liquid splashing. The liquid splashing can be prevented by increasing the discharge flow rate of IPA from the drying liquid nozzle, but this also increases the amount of expensive IPA used.

[0063] In the above embodiment, both landing points are moved radially outward together to always satisfy the condition that the distance from the center of rotation Wc of the landing point of the DIW from the rinse nozzle 43 is greater than the distance from the center of rotation Wc of the landing point of the IPA from the drying liquid nozzle 42. Therefore, regardless of the radial position of the landing point of the DIW, the thickness of the IPA liquid film at the landing point of the DIW is maintained at a sufficient thickness, thereby preventing the occurrence of liquid splashing.

[0064] [Drying process] After the second stage of the IPA replacement process is completed (i.e., after the IPA replacement process is completed), the drying process is performed. First, from the state of Fig. 4(F), while continuing to discharge IPA from the drying liquid nozzle 42, the position of the landing point of the IPA is moved in the positive direction from the rotation center Wc of the substrate W toward the periphery. Simultaneously with the movement of the drying liquid nozzle 42, the gas nozzle 44 supported by the second nozzle arm 52 is also moved toward the periphery of the substrate while discharging nitrogen gas as a drying gas from the gas nozzle 44.

[0065] At this time, the drying liquid nozzle 42 and the gas nozzle 44 are moved in opposite directions so as to constantly satisfy the condition that the position of the landing point of the IPA is radially outward of the position of the collision point of the main stream of nitrogen gas discharged from the gas nozzle 44 with the surface of the substrate W. As a result, the circular dry area formed in the center of the substrate W gradually spreads in the radial direction, and eventually the entire surface of the substrate W is dried. It is preferable to move the drying liquid nozzle 42 and the gas nozzle 44 so that the main stream of gas is sprayed to a position slightly radially inward of the boundary between the dry area and the non-dry area (area where the IPA liquid film exists) on the surface of the substrate W.

[0066] With the above, a series of processes for one substrate W is completed.

[0067] According to the above embodiment, it is possible to maintain a state in which a liquid film continues to exist on the entire surface of the substrate W, while preventing the occurrence of liquid splashes.

[0068] In the above embodiment, in the IPA replacement step, after the landing point of the IPA from the drying liquid nozzle 42 coincides with the rotation center Wc, the moving direction of the drying liquid nozzle 42 is reversed and moved in the positive direction (see (C) to (E) of FIG. 4), but this is not limited to this. As shown in (C) to (E) of FIG. 6, the drying liquid nozzle 42 may be moved in the negative direction (i.e., to region II) like the rinsing nozzle 43.

[0069] When IPA and DIW are simultaneously discharged in the IPA replacement process, the auxiliary nozzle 70 shown in Fig. 7 and Fig. 8 can be used as a nozzle for discharging DIW. In this case, the auxiliary nozzle 70 is further added to the processing unit 16 in addition to the configuration shown in Fig. 2 and Fig. 3. Therefore, during normal rinsing processing, the chemical / rinse nozzle 41 or the rinse nozzle 43 can be used.

[0070] The auxiliary nozzle 70 can be provided, for example, on the upper surface of the liquid receiving cup 60 near the upper opening of the liquid receiving cup 60. The auxiliary nozzle 70 ejects the DIW so as to describe a generally parabolic trajectory as shown in FIG. 7. The auxiliary nozzle 70 can rotate (swing) as shown by arrow 71, thereby changing the landing point (radial position of the landing point) of the DIW ejected from the auxiliary nozzle 70 on the substrate W. The rotation range of the auxiliary nozzle 70 is determined in consideration of the rotation direction of the substrate W (arrow ω) so that the vector indicated by the DIW ejected from the auxiliary nozzle 70 is generally aligned with the vector indicating the motion direction of the substrate W at the landing point of the DIW in a plan view (at least the two vectors do not point in opposite directions).

[0071] In addition, since the IPA used in the IPA replacement process has a surface tension significantly lower than that of DIW, it effectively suppresses pattern collapse due to surface tension in the subsequent drying process. IPA not only has a surface tension lower than DIW, but is also more volatile than DIW and is easily replaced with DIW, so it is widely used in the manufacture of semiconductor devices to cover the surface of a substrate immediately before the drying process. It is possible to use a liquid other than IPA in the IPA replacement process instead of IPA as long as it has the same properties as IPA (especially low surface tension). In this case, the IPA replacement process is called a drying liquid replacement process. In addition, the drying process is not limited to the drying method described in the above embodiment, and for example, a supercritical drying method can also be used.

[0072] In the above embodiment, the replacement step of replacing DIW with IPA (IPA replacement step) has been described, but the technology used in the IPA replacement step can be widely used in a step of replacing a first processing liquid covering the surface of a substrate with a second processing liquid having a smaller surface tension than the first processing liquid. In this case, too, when replacing the first processing liquid with the second processing liquid, it is possible to prevent the occurrence of liquid splashing while maintaining a state in which a liquid film continues to exist on the entire surface of the substrate W.

[0073] The embodiments disclosed herein should be considered as illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

[0074] The substrate is not limited to a semiconductor wafer, but may be other types of substrates used in the manufacture of semiconductor devices, such as glass substrates, ceramic substrates, etc.

Claims

1. a first processing step of supplying a first processing liquid onto a surface of a rotating substrate to cover the surface of the substrate with a liquid film of the first processing liquid; a second processing step of supplying a second processing liquid having a surface tension smaller than that of the first processing liquid onto the surface of the rotating substrate after the first processing step, and replacing the first processing liquid on the substrate with the second processing liquid, thereby covering the surface of the substrate with a liquid film of the second processing liquid; Equipped with The second processing step includes: a first step of simultaneously supplying the first processing liquid in addition to the second processing liquid to a surface of the rotating substrate; a second step of supplying the second processing liquid to a center of the surface of the rotating substrate without supplying the first processing liquid after the first step; Including, The first stage comprises: a first step of supplying the second processing liquid to a center of a surface of the rotating substrate while supplying the first processing liquid to the surface of the rotating substrate; a second step of supplying both the first processing liquid and the second processing liquid onto the surface of the rotating substrate while increasing both the first radial distance and the second radial distance, while maintaining a condition that a first radial distance, which is a distance from a rotation center of the substrate to a landing point of the first processing liquid on the surface of the substrate, is greater than a second radial distance, which is a distance from the rotation center of the substrate to a landing point of the second processing liquid, and while controlling at least one of a supply flow rate of the second processing liquid and a rotation speed of the substrate so that a liquid film of the second processing liquid is maintained at a center of the surface of the substrate; Including, the second stage is started by stopping the supply of the first processing liquid to the surface of the rotating substrate when the landing point of the first processing liquid reaches the peripheral portion of the surface of the substrate by the second step, and the second stage includes a third step of moving the landing point of the second processing liquid on the surface of the substrate to the center of the surface of the substrate while continuing the supply of the second processing liquid to the surface of the rotating substrate. A method for processing a substrate.

2. 2. The substrate processing method according to claim 1, wherein in the second step, a difference between the first radial distance and the second radial distance is maintained within a range of 40 mm to 90 mm.

3. 3. The substrate processing method according to claim 1, wherein in the second step, a difference between the first radial distance and the second radial distance is maintained constant.

4. A substrate processing method described in any one of claims 1 to 3, wherein in the first step, a first position, which is the position of the landing point of the second processing liquid, coincides with the center of rotation of the substrate or is located close to the center of rotation of the substrate to such an extent that the center of rotation of the substrate is covered by the second processing liquid.

5. The first processing liquid is continuously supplied to the rotating substrate from the time when a first processing step is performed until the supply is stopped due to the start of a second stage of a second processing step, 5. A substrate processing method as described in claim 4, wherein the landing point of the first processing liquid at the end of the first processing process coincides with the center of rotation of the substrate, and then, in a first step of the second processing process, the landing point of the first processing liquid is moved away from the center of rotation of the substrate while the landing point of the second processing liquid is moved to the center of rotation of the substrate.

6. 6. A substrate processing method as described in claim 5, wherein at least at the end of the first processing step, a position of a landing point of the first processing liquid on the surface of the substrate coincides with a center of rotation of the substrate or is located close to the center of rotation of the substrate to such an extent that the center of rotation of the substrate is covered by the first processing liquid.

7. 7. The substrate processing method according to claim 6, wherein a supply flow rate of the first processing liquid in the first step of the second processing process is smaller than a supply flow rate of the first processing liquid in the first processing process.

8. 8. A substrate processing method according to claim 1, wherein, in the third step of the second stage of the second processing process, after the landing point of the second processing liquid on the surface of the substrate is moved to the center of the surface of the substrate, the second processing liquid is continuously supplied to the center of the surface of the substrate.

9. 9. A substrate processing method according to claim 1, wherein a supply flow rate of the second processing liquid after moving a landing point of the second processing liquid on the surface of the substrate to a center of the surface of the substrate in the third step of the second stage of the second processing process is greater than a supply flow rate of the second processing liquid in the first step and the second step of the second stage.

10. 10. A substrate processing method according to claim 1, wherein in the first step of the first stage of the second processing process, the landing point of the second processing liquid coincides with the center of rotation of the substrate or is located close to the center of rotation of the substrate to such an extent that the center of rotation of the substrate is covered by the second processing liquid.

11. 11. The substrate processing method of claim 10, wherein in the third step of the second stage of the second processing process, the landing point of the second processing liquid is moved to the center of the surface of the substrate before a dry area not covered by a liquid film is generated near the rotation center of the substrate.

12. 12. A substrate processing method according to claim 1, wherein in the second processing step, the first processing liquid is supplied from a first nozzle carried by a first nozzle arm, and the second processing liquid is supplied from a second nozzle carried by a second nozzle arm.

13. 13. The substrate processing method according to claim 1, wherein the first processing liquid is a rinsing liquid, and the second processing liquid is an organic solvent having a surface tension lower than that of the rinsing liquid.

14. 14. The substrate processing method according to claim 13, wherein the rinsing liquid is made of pure water or functional water in which a trace amount of an electrolyte component is dissolved in pure water.

15. 15. The substrate processing method according to claim 1, further comprising a chemical processing step of supplying a chemical liquid to a surface of the rotating substrate, the first processing step being a rinsing step of rinsing the chemical liquid by supplying a rinsing liquid as the first processing liquid to the substrate that has been subjected to the chemical processing step.

16. A substrate processing apparatus, comprising: a substrate holder that holds the substrate in a horizontal position; a rotation drive unit that rotates the substrate holder that holds the substrate about a vertical axis; at least two nozzles provided so as to be able to supply a processing liquid to the substrate held by the substrate holding part, supply a rinsing liquid to the substrate held by the substrate holding part, supply a low surface tension liquid to the substrate held by the substrate holding part, and simultaneously supply a rinsing liquid and a low surface tension liquid to the substrate held by the substrate holding part; at least one nozzle arm for moving the at least two nozzles; a control unit that controls an operation of the substrate processing apparatus to cause the substrate processing apparatus to perform the substrate processing method according to any one of claims 1 to 15; A substrate processing apparatus comprising:

Images