Substrate processing apparatus and substrate processing method

Abstract

To reduce particles on a lower surface of a substrate.SOLUTION: A substrate processing device comprises: a substrate holding part that comprises a disc-like base member and a plurality of holding members provided at a peripheral edge part of the base member to hold a substrate so that the substrate is separated upward from the base member, the substrate holding part holding the substrate in a horizontal attitude; a rotary drive part that rotates and drives the substrate holding part around a vertical axis line; a processing liquid nozzle that supplies processing liquid to the substrate held by the substrate holding part; a purge gas nozzle that discharges a purge gas into a substrate lower space formed between a lower surface of the substrate held by the substrate holding part and a top surface of the base member; a purge gas flow rate control device that controls a flow rate of the purge gas discharged from the purge gas nozzle; and a control part. The control part controls an operation of the gas flow rate control device so as to discharge the purge gas from the purge gas nozzle into the substrate lower space at such a flow rate that a negative pressure generated in the substrate lower space with rotation of the substrate holding part holding the substrate is canceled.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] In the manufacture of semiconductor devices, a substrate processing apparatus is used that rotates a substrate held in a horizontal posture around a vertical axis while performing a cleaning process on the upper surface and / or the lower surface of the substrate. Patent Document 1 describes an example of such a substrate processing apparatus. This substrate processing apparatus is provided with a disk-shaped spin base and three or more substrate holding members provided near the peripheral edge of the spin base. A cleaning liquid supply portion and a gas ejection port are provided at the central portion of the spin base. A cleaning process for cleaning the lower surface of the substrate is performed by supplying a cleaning liquid to the central portion of the lower surface of the substrate by the cleaning liquid supply portion while rotating the substrate. Thereafter, a drying process for drying the substrate is performed by stopping the supply of the cleaning liquid and continuing the rotation of the substrate.

[0003] During the drying process, gas (inert gas or dry air) is supplied from the gas ejection port to the space below the substrate to promote drying. If the cleaning liquid enters the gas ejection port during the cleaning process, the entered cleaning liquid is blown out in a mist form at the start of gas ejection, contaminating the substrate. To prevent this, even during the cleaning process, gas is blown out from the gas ejection port at a flow rate smaller than that during the drying process.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present disclosure provides a technique capable of reducing particles on the lower surface of a substrate.

Means for Solving the Problems

[0006] According to an embodiment of the present disclosure, there is provided a substrate processing apparatus including a disk-shaped base member, a plurality of holding members provided at a peripheral edge of the base member for holding a substrate such that the substrate is spaced upward from the base member, a substrate holding portion for holding the substrate in a horizontal posture, a rotation driving portion for rotationally driving the substrate holding portion around a vertical axis, a processing liquid nozzle for supplying a processing liquid to the substrate held by the substrate holding portion, a liquid receiving cup provided around the substrate holding portion for receiving the processing liquid scattered from the substrate held and rotated by the substrate holding portion, a cup exhaust passage for sucking the atmosphere in the liquid receiving cup, one end of which is connected to an exhaust port of the liquid receiving cup and the other end of which is connected to a negative pressure generation source, a purge gas nozzle for discharging a purge gas into a substrate lower space formed between a lower surface of the substrate held by the substrate holding portion and an upper surface of the base member, a purge gas flow rate control device for controlling a flow rate of the purge gas discharged from the purge gas nozzle, and a control portion for controlling at least an operation of the purge gas flow rate control device. The control portion controls an operation of the purge gas flow rate control device such that the purge gas is discharged into the substrate lower space from the purge gas nozzle at a flow rate that cancels a negative pressure generated in the substrate lower space as the substrate holding portion holding the substrate rotates. A substrate processing apparatus is provided.

Advantages of the Invention

[0007] According to the present disclosure, particles on the lower surface of the substrate can be reduced.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0009] An embodiment of a substrate processing apparatus will be described with reference to the accompanying drawings.

[0010] FIG. 1 is a diagram showing a schematic configuration of a substrate processing system according to the present embodiment. Hereinafter, in order to clarify the positional relationship, X-axis, Y-axis, and Z-axis orthogonal to each other are defined, and the positive direction of the Z-axis is the vertically upward direction.

[0011] As shown in FIG. 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.

[0012] The loading / unloading station 2 includes a carrier placement unit 11 and a transfer unit 12. On the carrier placement unit 11, a plurality of carriers C for horizontally accommodating a plurality of substrates, semiconductor wafers (hereinafter referred to as wafers W) in the present embodiment, are placed.

[0013] The transfer unit 12 is provided adjacent to the carrier placement unit 11 and includes a substrate transfer device 13 and a delivery unit 14 inside. The substrate transfer device 13 includes a wafer holding mechanism for holding the wafer W. Further, the substrate transfer device 13 can move in the horizontal and vertical directions and turn around the vertical axis, and transfers the wafer W between the carrier C and the delivery unit 14 using the wafer holding mechanism.

[0014] The processing station 3 is provided adjacent to the transfer unit 12. The processing station 3 includes a transfer unit 15 and a plurality of processing units 16. The plurality of processing units 16 are arranged side by side on both sides of the transfer unit 15.

[0015] The transfer unit 15 includes a substrate transfer device 17 inside. The substrate transfer device 17 includes a wafer holding mechanism for holding the wafer W. Further, the substrate transfer device 17 can move in the horizontal and vertical directions and turn around the vertical axis, and transfers the wafer W between the delivery unit 14 and the processing unit 16 using the wafer holding mechanism.

[0016] The processing unit 16 performs predetermined substrate processing on the wafer W transferred by the substrate transfer device 17.

[0017] Also, the substrate processing system 1 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. Programs for controlling various processes executed in the substrate processing system 1 are stored in the storage unit 19. The control unit 18 controls the operation of the substrate processing system 1 by reading and executing the programs stored in the storage unit 19.

[0018] Note that such programs may have been recorded on 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 hard disks (HD), flexible disks (FD), compact disks (CD), magneto-optical disks (MO), memory cards, and the like.

[0019] In the substrate processing system 1 configured as described above, first, the substrate transfer device 13 of the loading / unloading station 2 takes out the wafer W from the carrier C placed on the carrier placement unit 11 and places the taken-out wafer W on the delivery unit 14. The wafer W placed on the delivery unit 14 is taken out from the delivery unit 14 by the substrate transfer device 17 of the processing station 3 and carried into the processing unit 16.

[0020] The wafer W carried into the processing unit 16 is processed by the processing unit 16, then carried out from the processing unit 16 by the substrate transfer device 17 and placed on the delivery unit 14. And the processed wafer W placed on the delivery unit 14 is returned to the carrier C on the carrier placement unit 11 by the substrate transfer device 13.

[0021] Next, the configuration of the processing unit 16 will be described with reference to FIG. 2.

[0022] As shown in FIG. 2, the processing unit 16 includes a chamber 20, a substrate holding and rotating mechanism 30, a processing fluid supply unit 40, a liquid receiving cup 50, and a rotating cup 60.

[0023] The chamber 20 houses the substrate holding and rotating mechanism 30, the processing fluid supply unit 40, and the liquid receiving cup 50. An FFU (Fan Filter Unit) 21 is provided on the ceiling of the chamber 20. The FFU 21 forms a downflow in the chamber 20.

[0024] The substrate holding and rotating mechanism 30 has a substrate holding part 31 and a rotation driving part 33. The substrate holding part 31 has a disk-shaped base plate 311 having a diameter slightly larger than that of the wafer W, a plurality of chuck parts (holding members) 312 provided at the peripheral edge of the base plate 311, and a hollow rotating shaft 313 extending downward from the central part of the lower surface of the base plate 311. By gripping the wafer W with the chuck parts 312, the wafer W is held on the substrate holding part 31 in a horizontal posture. The rotation driving part 33 is composed of, for example, an electric rotating motor and can rotate the rotating shaft 313 around the vertical axis.

[0025] The substrate holding part 31 further has a substrate lifting part 314. The substrate lifting part 314 has a disk body 315 that fits into a circular depression formed on the upper surface of the base plate 311 of the substrate holding part 31, a plurality of support pins 316 protruding from the upper surface of the disk body 315, and a hollow shaft 317 extending downward from the central part of the lower surface of the disk body 315. The shaft 317 of the substrate lifting part 314 is accommodated inside the rotation shaft 313 of the substrate holding part 31.

[0026] To raise and lower the substrate lifting part 314, a lifting mechanism 318 is provided. The lifting mechanism 318 has, for example, a linear actuator 319 such as an air cylinder or a ball screw, and a lift member 320 that moves in the vertical direction by the linear actuator 319 and pushes up the lower end of the shaft 317. By the lifting mechanism 318, the disk body 315 can be moved between a lowered position (the position shown in FIG. 2) and a raised position (a position away from the base plate 311 upward).

[0027] The chuck part 312 of the substrate holding part 31 can be moved between a gripping position where the peripheral edge of the wafer W is gripped and a releasing position where it is separated from the wafer W by a chuck operation mechanism attached to the base plate 311. The chuck operation mechanism is, for example, composed of a link mechanism that operates by being pushed by the disk body 315 moving to the lowered position. The chuck operation mechanism is configured to position the chuck part 312 at the gripping position when the disk body 315 is in the lowered position and to position the chuck part 312 at the releasing position when the disk body 315 is in the raised position. Such a chuck operation mechanism is well-known and its illustration and description are omitted.

[0028] At least when the disk body 315 is in the lowered position, the base plate 311 and the disk body 315 rotate integrally by a suitable interlock structure composed of complementary unevenness (for example, protrusions provided on one of the upper surface of the disk body 315 and the lower surface of the base plate 311 and depressions provided on the other).

[0029] That is, the base plate 311 and the disk body 315 are relatively movable up and down, but at least when the disk body 315 is in the lowered position, or always, the base plate 311 and the disk body 315 are non-rotatable relative to each other. The rotation axis 313 of the base plate 311 and the axis 317 of the disk body 315 may be engaged so as to be relatively movable up and down and non-rotatable relative to each other.

[0030] When the wafer W is carried into the processing unit 16, the disk body 315 of the substrate lifting unit 314 is positioned at the raised position. In this state, the arm of the substrate transfer device 17 that has entered the chamber 20 through a transfer port (not shown) provided on the side wall of the chamber 20 passes the wafer W to the support pin 316 of the substrate lifting unit 314. Thereafter, the disk body 315 is lowered to the lowered position. Along with this movement, the chuck unit 312 that has moved to the gripping position grips the wafer W, and the wafer W slightly separates from the support pin 316. Further, the disk body 315 engages with the base plate 311 of the substrate holding unit 31 in a non-rotatable manner. As a result, the wafer W is firmly held by the substrate holding unit 31. When the wafer W is carried out from the processing unit 16, the reverse procedure to the above may be executed.

[0031] Inside the shaft 317 of the substrate lifting unit 314, a purge gas supply pipe 91 (purge gas nozzle) is provided. The inside of the purge gas supply pipe 91 serves as a purge gas supply path. At the upper end of the purge gas supply pipe 91, one or more purge gas injection holes 92 for injecting purge gas into the space between the base plate 311 and the disk body 315 are provided.

[0032] The one or more purge gas injection holes 92 can include at least any one of a purge gas injection hole for injecting purge gas directly upward, a purge gas injection hole for injecting horizontal purge gas, and a purge gas injection hole for injecting purge gas obliquely upward. When providing a plurality of purge gas injection holes in this way, a cap in which a plurality of purge gas injection holes are formed may be attached to the upper end of the purge gas supply pipe 91.

[0033] The purge gas supply pipe 91 is provided so as to maintain a non-rotating state even when the rotation axis 313 of the substrate holding unit 31 and the axis 317 of the substrate elevating unit 314 are rotating. The purge gas supply pipe 91 is provided so as not to move in the vertical direction even when the axis 317 of the substrate elevating unit 314 is moved up and down.

[0034] Instead of providing the purge gas supply pipe 91 inside the axis 317, a cavity inside the axis 317 may be provided as a purge gas supply path. In this case, the axis 317 serves as a purge gas nozzle. Also in this case, for example, the purge gas can be supplied into the purge gas supply path via a rotary joint connected to the lower end portion of the axis 317.

[0035] A purge gas supply mechanism 94 is connected to the purge gas supply pipe 91. The purge gas supply mechanism 94 includes a purge gas supply source 941 (for example, a nitrogen gas supply source for industrial use), a gas supply path 942 connected to the purge gas supply pipe 91, and flow control devices 943 such as an on-off valve, a flow control valve, and a flow meter interposed in the gas supply path 942. Dry air can also be used as the purge gas.

[0036] The processing fluid supply unit 40 supplies a processing fluid (processing liquid, processing gas, etc.) to the wafer W. The processing fluid supply unit 40 includes a plurality of processing liquid nozzles 41, 42, 43 that discharge (supply) the processing liquid toward the wafer W held and rotated by the substrate holding unit 31. For example, a cleaning chemical solution (for example, DHF (dilute hydrofluoric acid)) is discharged from the processing liquid nozzle 41, DIW (deionized water, that is, pure water) as a rinse liquid is discharged from the processing liquid nozzle 42, and an organic solvent for drying assistance having high volatility and low surface tension, for example, IPA (isopropyl alcohol), is discharged from the processing liquid nozzle 43. An alkaline chemical solution such as SC-1 may be included as the processing liquid. The processing fluid may include a drying assistance gas such as nitrogen gas sprayed onto the surface of the wafer W to promote drying of the surface of the wafer W.

[0037] Each processing liquid nozzle (41 - 43) is provided with a processing liquid supply mechanism (not shown) having a processing liquid supply path connected to a processing liquid supply source and provided with a flow regulator such as an on-off valve and a flow rate adjustment valve, from which each processing liquid (processing fluid) is supplied.

[0038] The processing liquid nozzles 41 - 43 are attached to one or more (one in the illustrated example) nozzle arms 44. The nozzle arm 44 can be moved up and down and pivoted by an arm drive mechanism 45, whereby it can move between a processing position (any position between directly above the center of the wafer W and directly above the peripheral edge of the wafer) and a standby position outside the liquid receiving cup 50.

[0039] The liquid receiving cup 50 has a plurality of cup bodies, two cup bodies (51, 52) in the illustrated example, and one of the cup bodies (52) is movable for flow path switching. Specifically, the liquid receiving cup 50 has a stationary annular first cup body 51 located on the outside, a vertically movable annular second cup body 52 located inside thereof, and a stationary inner wall 54 located further inside thereof.

[0040] In this specification, when referring to the "radial direction" and the "circumferential direction", unless otherwise specified, it generally means the radial (or diametral) direction and the circumferential direction centered on the central axis (which is the same as the rotation central axis of the substrate holding portion 31) in the liquid receiving cup formed as a generally rotating body (a rotating body in geometric terms).

[0041] The second cup body 52 in the raised position is shown on the left side of FIG. 2, and the second cup body 52 in the lowered position is shown on the right side of FIG. 2. The first and second cup bodies 51, 52 and the inner wall 54 do not rotate. A first flow path 501 is formed between the first cup body 51 and the second cup body 52, and a second flow path 502 is formed between the second cup body 52 and the inner wall 54.

[0042] The second cup body 52 can be moved up and down by the elevating mechanism 52EV schematically shown in FIG. 2. When the second cup body 52 is in the lowered position, the overhanging portion 5102 of the first cup body 51 and the overhanging portion 5202 of the second cup body 52 are separated from each other, and the first flow path 501 opens toward the vicinity of the periphery of the wafer W (see the right half of FIG. 2). When the second cup body 52 is in the raised position, the overhanging portion 5102 and the overhanging portion 5202 are close to each other, and the second flow path 502 opens toward the vicinity of the periphery of the wafer W (see the left half of FIG. 2).

[0043] Bending portions are provided in the middle of each of the first flow path 501 and the second flow path 502. By abruptly changing the direction at the bending portions, the liquid component is separated from the gas-liquid mixed fluid flowing through each flow path. The separated liquid component drops into the liquid receivers 511 corresponding to the first flow path 501 and the liquid receivers 512 corresponding to the second flow path 502. The liquid receivers 511 and 512 are connected to the factory liquid drainage system (schematically shown by arrows) according to the types of chemical solutions (acidic, alkaline, organic (acidic and organic in this example)).

[0044] At the bottom of the liquid receiving cup 50, a cup exhaust port 55 communicating with the first flow path 501 and the second flow path 502 is formed. A cup exhaust path 56 is connected to the cup exhaust port 55.

[0045] Below the chamber 20 (the housing of the processing unit 16) and outside the liquid receiving cup 50, a chamber exhaust port 57 for exhausting the atmosphere in the chamber 20 is provided. A chamber exhaust path 58 is connected to the chamber exhaust port 57. A flow control valve, such as a butterfly valve 59, is interposed in the chamber exhaust path 58.

[0046] The chamber exhaust passage 58 merges into the cup exhaust passage 56. A switching valve 53 is provided in the cup exhaust passage 56 on the downstream side of the merging portion. By switching the switching valve 53, the cup exhaust port 55 can be communicated with a factory exhaust system (acid exhaust system, alkali exhaust system, organic exhaust system, etc.) according to the type of exhaust. Since the factory exhaust system is at a negative pressure (the level of the negative pressure is generally maintained constant), the atmosphere in the space communicating with the factory exhaust system (the space in the liquid receiving cup 50, the cup exhaust passage 56, the chamber exhaust passage 58, etc.) is sucked.

[0047] By adjusting the opening degree of the butterfly valve 59 in the chamber exhaust passage 58, the exhaust flow rate ratio between the cup exhaust passage 56 and the chamber exhaust passage 58 can be adjusted. When the opening degree of the butterfly valve 59 is reduced, the exhaust flow rate of the cup exhaust passage 56 increases, and as a result, the inside of the liquid receiving cup 50 is sucked more strongly.

[0048] The butterfly valve 59 may be provided only in the cup exhaust passage 56, or the butterfly valve 59 may be provided in both the cup exhaust passage 56 and the chamber exhaust passage 58.

[0049] The rotating cup 60 is attached to the base plate 311 of the substrate holding portion 31 and rotates together with the base plate 311. The rotating cup 60 has an upper cup body 61 and a lower cup body 62. The upper cup body 61 and the lower cup body 62 are fixed to the base plate 311 by a plurality of fixing members 63 (only one is shown in FIG. 2) attached to the outer peripheral portion of the base plate 311 at intervals along the circumferential direction.

[0050] When the inside of the liquid receiving cup 50 is sucked through the cup exhaust passage 56, the gas (clean air discharged from the FFU) in the space above the upper opening of the liquid receiving cup 50 is drawn into the liquid receiving cup 50. Most of the air drawn into the liquid receiving cup 50 flows into the first flow path 501 or the second flow path 502 through the space between the upper cup body 61 and the lower cup body 62 (see arrow F1).

[0051] Further, when the substrate holding unit 31 and the wafer W rotate, the gas (clean air, nitrogen gas, etc.) near the surface of the disk-shaped rotating body (such as the wafer W, the base plate 311, the disk body 315, etc.) is dragged on the surface of the rotating body and flows toward the outer peripheral edge of the rotating body. The gas flowing on the upper surface (front surface) side of the wafer W (see arrow F2) mainly flows through the space between the upper cup body 61 and the lower cup body 62 and flows into the first flow path 501 or the second flow path 502. The gas flowing through the space between the lower surface (back surface) of the wafer W and the base plate 311 and the disk body 315 (hereinafter, simply referred to as "wafer lower space S0" for convenience) (see arrow F3) mainly flows through the space between the lower cup body 62 and the base plate 311 and flows into the first flow path 501 or the second flow path 502.

[0052] In addition, in this application, an example of the specific shape and configuration of the liquid receiving cup 50 and the rotating cup 60 schematically shown is described in detail in the patent publication (Japanese Patent Laid-Open No. 2014-123713) related to the prior patent application (Japanese Patent Application No. 2013-205418) by the applicant of this application, so please also refer to this.

[0053] Next, the operation of the processing unit 16 automatically performed under the control of the control device 4 will be briefly described.

[0054] The unprocessed wafer W is carried into the processing unit 16 by the substrate transfer device 17 and held by the substrate holding unit 31. That is, the state shown in FIG. 2 is achieved. Next, the wafer W starts to rotate. First, a chemical solution (for example, an acidic chemical solution such as DHF) is supplied to the surface of the rotating wafer W, and a chemical solution cleaning process is performed (chemical solution cleaning step). Next, a rinse solution (for example, DIW) is supplied, and a rinsing process is performed (rinsing step).

[0055] Thereafter, a drying liquid (for example, IPA) is supplied to the surface of the rotating wafer W, and the rinse liquid on the surface of the wafer W is replaced with the drying liquid (drying liquid replacement step). Next, the supply of the drying liquid is stopped, and the wafer W is continuously rotated to dry the wafer W (drying step).

[0056] While the above process is being executed, the processing liquid (chemical solution, rinse liquid, drying liquid, etc.) supplied to the surface of the wafer W scatters outward from the wafer W due to centrifugal force. The scattered liquid becomes minute droplets (mist) and drifts around the wafer W (especially in the space near the peripheral edge of the wafer W). If this mist reattaches to the wafer W, it causes particles.

[0057] Since the internal space of the liquid receiving cup 50 is constantly sucked through the cup exhaust passage 56, the clean gas (clean air, clean dry air, or clean air mixed with nitrogen gas, etc.) flowing downward from the FFU 21 is drawn into the liquid receiving cup 50, passes through the vicinity of the peripheral edge of the wafer W, and flows into the first flow path 501 or the second flow path 502 (see arrow F1), and is discharged from the liquid receiving cup 50 through the cup exhaust port 55. The mist drifting in the space near the peripheral edge of the wafer W rides on the flow of the above clean gas and flows into the first flow path 501 or the second flow path 502. The mist is separated from the clean gas while flowing through the first flow path 501 or the second flow path 502, and is discharged from the liquid receiving cup 50 through the drain port 521 or the drain port 522.

[0058] Here, attention is paid to the space S0 below the wafer. When the wafer W is rotating, as described above, the gas in the space S0 below the wafer is dragged by the rotation of the wafer W, the base plate 311, and the disk body 315 and flows toward the space on the outer side in the radial direction of the space S0 below the wafer (see arrow F3). Since the gas in the space S0 below the wafer thus goes out to the outside, the pressure in the space S0 below the wafer (hereinafter referred to as "pressure P0") decreases.

[0059] The region near the outlet of the space between the upper cup body 61 and the lower cup body 62 in the first flow path 501 is referred to as "region S1", and the pressure in region S1 is referred to as "pressure P1". Also, the region near the outlet of the space between the upper cup body 61 and the lower cup body 62 in the second flow path 502 is referred to as "region S2", and the pressure in region S2 is referred to as "pressure P2". Further, the region slightly upstream from the confluence point with the chamber exhaust path 58 in the cup exhaust path 56 is referred to as "region S3", and the pressure in region S3 is referred to as "pressure P3". Moreover, the space outside the liquid receiving cup 50 and above the upper surface (front surface) of the wafer W in the chamber 20 is referred to as "space SC", and the pressure in space SC is referred to as "pressure PC".

[0060] When the inlet of the first flow path 501 is open, if the pressure P0 in the space S0 below the wafer is lower than the pressure P1 in region S1 of the first flow path 501, a part of the gas containing the mist of the processing liquid existing in region S1 (for example, passing through the gap between the outer peripheral edge of the lower cup body 62 and the outer peripheral edge of the base plate 311) flows into the space S0 below the wafer. The mist that has flowed into the space S0 below the wafer adheres to the lower surface (back surface) of the wafer W and causes particles. Therefore, in order to prevent contamination of the lower surface of the wafer W, it is desirable that pressure P0 ≥ pressure P1 (hereinafter referred to as "condition 1") at least while the mist of the processing liquid is floating in region S1.

[0061] Similarly, when the inlet of the second flow path 502 is open, it is desirable that pressure P0 ≥ pressure P2 (hereinafter referred to as "condition 1'").

[0062] Also, when the pressure P0 in the space S0 below the wafer is lower than the pressure PC in the region SC above the peripheral edge of the wafer, a part of the gas containing the mist of the processing liquid existing in region SC (for example, passing through the gap between the outer peripheral edge of the lower cup body 62 and the outer peripheral edge of the wafer W) flows into the space S0 below the wafer. Therefore, in order to prevent contamination of the lower surface of the wafer W, it is desirable that pressure P0 ≥ pressure PC (hereinafter referred to as "condition 2") at least while the mist of the processing liquid is floating in region SC.

[0063] However, it is not preferable to reduce the pressures P1 and PC to satisfy Conditions 1 and 2. The gas flow (flow velocity, turbulent flow generation situation, etc.) in the vicinity of the peripheral portion of the wafer W is mainly determined by the difference between the pressure PC in the space SC and the pressure P1 in the region S1. If the gas flow in the region S1 is inappropriate, for example, the mist of the processing liquid detached from the wafer W may reattach to the surface of the wafer W, and the most important surface of the wafer W may be contaminated. In order to minimize such a possibility, the cup exhaust flow rate (by which the pressure P1 is determined) is controlled. Further, the pressure PC in the space SC is determined by the gas (clean air) supply flow rate of the FFU and the chamber exhaust flow rate, but these two flow rates are not usually changed significantly and are generally maintained constant. That is, the pressures P1 and PC should not be values that are changed significantly only for the purpose of preventing contamination of the lower surface of the wafer W.

[0064] In an aspect of the operation of the actual apparatus, the cup exhaust flow rate is controlled by controlling the opening degree of the butterfly valve 59 of the chamber exhaust passage 58 so that an optimal air flow is formed particularly in the vicinity of the wafer W according to the content of the liquid treatment and the rotation speed of the wafer W. The negative pressure of the factory exhaust system is generally maintained constant. When the opening degree of the butterfly valve 59 is increased, the exhaust flow rate of the chamber exhaust passage 58 increases while the exhaust flow rate of the cup exhaust passage 56 decreases, and vice versa when the opening degree of the butterfly valve 59 is decreased. When the cup exhaust flow rate is decreased, the pressure P3 in the region S3 of the cup exhaust passage 56 becomes high, and when the cup exhaust flow rate is increased, the pressure P3 in the region S3 of the cup exhaust passage 56 becomes low.

[0065] The graph in Fig. 3 shows an example of the operation of the actual apparatus. In the graph of Fig. 3, the horizontal axis is the rotational speed (rpm) of the wafer W, and the vertical axis is the pressure P3 in the region S3 of the cup exhaust passage 56. The lower line indicates the control when the first flow path 501 is formed in the liquid receiving cup 50, and the upper line indicates the control when the second flow path 502 is formed in the liquid receiving cup 50. Since the shape of the first flow path 501 and the shape of the second flow path 502 are different from each other, the relationship between the wafer rotational speed and the pressure P3 (i.e., the opening degree of the butterfly valve 59) is changed so that an optimal airflow near the peripheral edge of the wafer W is formed for each.

[0066] In addition, the pressure P3 (i.e., the cup exhaust flow rate) may be changed depending on whether the processing liquid used is a chemical solution or a rinse liquid. This is because the adverse effect when the mist of the chemical solution reattaches to the wafer W is greater than the adverse effect when the mist of the rinse liquid reattaches to the wafer W.

[0067] The relationship shown in the graph of Fig. 3 is the relationship in a state where there is no gas discharge from the purge gas supply pipe 91. When the wafer W is rotated, gas is pushed into the first flow path 501 or the second flow path 502 due to the influence of the above-described airflows F2 and F3. Therefore, when the rotational speed of the wafer W increases, the pressure P3 in the region S3 of the cup exhaust passage 56 increases. The value of the pressure P3 shown in the graph of Fig. 3 is the value including this influence.

[0068] When the opening degree of the butterfly valve 59 is constant, when the pressure P3 in the region S3 of the cup exhaust passage 56 increases (decreases), the pressure P1 in the region S1 of the first flow passage 501 also increases (there is a positive correlation), and the tendency of the changes in the pressure P3 and the pressure P1 is also similar. It has already been confirmed that there is a relationship that the pressure P3 is higher than the pressure P1. Due to the structural reasons of the liquid receiving cup 50, it is difficult to directly measure the pressure P1. Therefore, in the following description, the pressure P3 measured by the pressure sensor provided in the cup exhaust passage 56 will be used as an index of the pressure P1 (an index of whether gas flows from the first flow passage 501 into the space S0 below the wafer). Incidentally, the same can be said about the relationship between the pressure P3 and the pressure P2 when the second flow passage 502 is open.

[0069] Here, return to the explanation of preventing the gas containing the mist of the processing liquid from entering the space S0 below the wafer. As described above, since it is not preferable to decrease (change) the pressure P1 (or the pressure P2), PC in order to satisfy the condition 1 (or the condition 1') and the condition 2, therefore, it is preferable to satisfy the above conditions 1 (or the condition 1'), 2 by increasing the pressure P0 in the space S0 below the wafer. For that purpose, it is only necessary to increase the flow rate of the gas discharged from the purge gas supply pipe 91 into the space S0 below the wafer.

[0070] However, if the discharge flow rate of the gas from the purge gas supply pipe 91 is excessively increased, it is also considered that the temperature of the wafer W at the portion where the gas collides may decrease, and the in-plane uniformity of the temperature of the wafer W may be impaired.

[0071] Next, the experimental results of examining the amount of particles generated on the back surface of the wafer W when liquid treatment is performed on the surface of the wafer W by changing the discharge flow rate of the purge gas from the purge gas supply pipe 91 (hereinafter, also referred to as "purge gas discharge flow rate B" for simplicity) will be described. The rotation speed of the wafer W (hereinafter, also referred to as "wafer rotation speed R" for simplicity) was set to 1000 rpm and 1500 rpm. In this experiment, the opening degree of the butterfly valve 59 corresponding to the wafer rotation speed R of 1000 rpm and 1500 rpm was set so that the pressure P3 in the region S3 of the exhaust passage 56 shown in the graph of FIG. 3 was realized when the purge gas discharge flow rate B was zero. That is, the pressure P3 was set to 59 kPa when the wafer rotation speed R was 1000 rpm, and the pressure P3 was set to 71 kPa when the wafer rotation speed R was 1500 rpm. The opening degree of the butterfly valve 59 was maintained at the opening degree when the purge gas discharge flow rate B was zero (that is, the opening degree of the butterfly valve 59 was not changed according to the change in the purge gas discharge flow rate B).

[0072] The results of the experiment conducted with the second flow path 502 formed in the liquid receiving cup 50 are shown in the graph of FIG. 4. In the graph of FIG. 4, the horizontal axis represents the purge gas discharge flow rate B (L / min), and the vertical axis represents the value obtained by subtracting the number of particles with a size of 40 nm or more before the liquid treatment from the number of particles with a size of 40 nm or more after the liquid treatment, that is, the particle number increment (ΔN) (Adder Particle Counts). The plots of ○ (open circles) show the data when the wafer rotation speed is 1000 rpm, and the plots of ● (black circles) show the data when the wafer rotation speed is 1500 rpm.

[0073] When the wafer rotation speed R is 1000 rpm, as the purge gas discharge flow rate B increases, the particle number increment (ΔN) decreases (because the pressure P0 in the lower space S0 of the wafer increases), and the particle number increment (ΔN) decreases to a level where there is no problem at 40 L / min. That is, at this time, it can be considered that the negative pressure generated in the lower space S0 of the wafer due to the rotation of the wafer W is offset by the purge gas supplied to the lower space S0 of the wafer.

[0074] Incidentally, as described above, when the wafer rotation speed R is constant, the opening degree of the butterfly valve 59 is maintained constant regardless of the purge gas discharge flow rate B. Therefore, as the gas inflow rate into the first flow path 501 increases due to the increase in the gas discharge flow rate from the purge gas supply pipe 91, the pressure P3 in the region S3 of the cup exhaust path 56 also increases. The pressure P3 when the purge gas discharge flow rate B is 0 L / min (no discharge) is 59 kPa, and the pressure P3 when the purge gas discharge flow rate B is 40 L / min was 62 kPa. The difference between the two (59 kPa - 62 kPa = -3 kPa) can be used as an index (ΔP) representing the depressurized state in the space S0 below the wafer when the wafer rotation speed is 1000 rpm.

[0075] Fig. 5 shows the relationship between the purge gas discharge flow rate B and the pressure P3 when the same experiment as above was conducted in each of the cases where the first flow path 501 is formed in the liquid receiving cup 50 and the case where the second flow path 502 is formed, when the wafer rotation speed R is 1000 rpm. In any case, it can be seen that the pressure P3 generally increases linearly as the purge gas discharge flow rate B increases.

[0076] Next, the case when the wafer rotation speed is 1500 rpm will be described. Also in this case, the opening degree of the butterfly valve 59 was controlled so that the pressure P3 in the region S3 of the cup exhaust path 56 when the purge gas discharge flow rate B is 0 L / min (no discharge) becomes the value (71 kPa) according to the graph in Fig. 3. In addition, the second flow path 502 was formed in the liquid receiving cup 50. In this case, as shown in the graph of Fig. 4, when the gas discharge flow rate reaches 70 L / min, the increase in the number of particles decreases to a level where there is no problem, and the pressure P3 at that time was 76 kPa. From this result, the value of the index (ΔP) representing the depressurized state in the space S0 below the wafer when the wafer rotation speed is 1500 rpm is 71 kPa - 76 kPa = -5 kPa.

[0077] From the above experimental results, it can be seen that the higher the wafer rotation speed R, the greater the degree of pressure reduction in the lower space S0 of the wafer, and the greater the purge gas discharge flow rate B required to eliminate the pressure reduction (that is, to prevent the mist of the processing liquid from entering the lower space S0 of the wafer). As described above, if the purge gas discharge flow rate B is made excessively large, there is a high possibility that the in-plane temperature uniformity of the wafer W will be impaired. For this reason, it is preferable to discharge the gas at the minimum necessary purge gas discharge flow rate B (a slightly larger flow rate is also acceptable) that satisfies the condition that the mist of the processing liquid does not enter the lower space S0 of the wafer.

[0078] Based on the above description, some specific examples of the control method of the purge gas discharge flow rate B in the processing unit 16 will be described. The control described below can be performed under the control of, for example, the control device 4 (see FIG. 1). The control program, processing recipe, etc. can be stored in the storage unit 19.

[0079] <First control method> In each time interval in the processing recipe, the purge gas discharge flow rate B is determined in advance by experiment. In all time intervals with different processing conditions, an experiment similar to the experiment described above with reference to FIG. 4 is performed to obtain a purge gas discharge flow rate B (preferably its minimum value) such that the particle increment (ΔN) does not become a problem. Then, the obtained purge gas discharge flow rate B is described in each time interval of the processing recipe. The control device 4 controls the purge gas supply mechanism 94 so that the purge gas discharge flow rate B described in the processing recipe stored in the storage unit 19 is realized.

[0080] Instead of experimentally determining the purge gas discharge flow rate B for all time intervals with different processing conditions, for a plurality of time intervals that are slightly different but similar in processing conditions, the purge gas discharge flow rate B for other time intervals may be determined based on the experiment conducted for the representative time interval. For example, for two different types of chemical solutions with little change in characteristics such as viscosity (characteristics related to mist formation), the purge gas discharge flow rate B determined for one chemical solution may be applied to the other chemical solution.

[0081] <Second control method> Based on a table (relationship table) or function obtained experimentally in advance, the purge gas discharge flow rate B may be obtained by calculation, and the control device 4 may control the purge gas supply mechanism 94 so that the purge gas discharge flow rate B obtained by calculation is realized. That is, in this case, the purge gas discharge flow rate B is not described in the processing recipe.

[0082] Examples of parameters (excluding the purge gas discharge flow rate B) that define the operating conditions of the processing unit capable of determining whether gas containing mist can enter the space S0 below the wafer are as follows. (1) The flow path (first flow path 501 or second flow path 502) in the liquid receiving cup 50 being used (this can be represented by, for example, the height position information of the second cup body 52 that can be raised and lowered) (2) The rotation speed of the wafer W (substrate holding unit 31) (3) The cup exhaust flow rate (set opening degree of the butterfly valve 59) (4) The type of processing liquid discharged from nozzles 41 to 43 (including temperature) (5) The position of the liquid landing point on the surface of the wafer W of the processing liquid discharged from nozzles 41 to 43 (including the case of nozzle scanning) (this can be represented by, for example, nozzle position information) (6) The discharge flow rate of the processing liquid from the nozzle (7) The supply flow rate of gas (e.g., clean air) from the FFU (8) The pressure SC in the chamber 20 (a pressure sensor can be provided to measure this) (9) Pressure P3 Note that since the above-described parameters are not completely independent and there are also parameters having a correlation relationship, a part of the parameters can be omitted. For example, since the chamber internal pressure SC is substantially determined by the gas supply flow rate from the FFU, either (6) or (7) can be omitted.

[0083] In the storage unit 19 of the control device 4, store a table or function showing the relationship between at least some of the above parameters (1) to (9) (for example, parameters (1) to (4)) and the purge gas discharge flow rate B to be adopted. The control device 4 reads at least some values of the above parameters described in the processing recipe stored in the storage unit 19, and applies the values to the above table or function to obtain the purge gas discharge flow rate B. Then, the control device 4 controls the purge gas supply mechanism 94 so that the obtained purge gas discharge flow rate B is realized.

[0084] <The Third Control Method> As schematically shown in FIG. 6, a pressure sensor 95 for directly measuring the pressure P0 in the space S0 below the wafer may be provided in the space S0 below the wafer. The detection signal of the pressure sensor 95 is output to the signal line 96. The signal line 96 can be drawn out through the cavity of the rotating shaft 313 into which the purge gas supply pipe 91 is inserted. The signal line 96 can be input to the control device 4, for example.

[0085] In order to arrange the pressure sensor 95 and the signal line 96 so as not to directly contact the rotating shaft 313 and not to contact the base plate 311 and the disk body 315, the signal line 96 may be formed of a sufficiently rigid thick coated wire. Alternatively, the signal line 96 may be housed inside a highly rigid sheath (not shown). By communicating the internal space of such a sheath with the atmospheric pressure space to supply the reference atmospheric pressure to the pressure sensor 95, the pressure sensor 95 may measure the gauge pressure.

[0086] When the pressure sensor 95 is provided in the space S0 below the wafer, for example, the following operation can be performed.

[0087] <Operation Example 1> In each time interval in the processing recipe, perform an experiment similar to the experiment executed to obtain the graph of FIG. 4 while changing the purge gas discharge flow rate B, and obtain the relationship between the detected value of the pressure sensor 95 and the particle increment (ΔN). Then, based on this relationship, obtain the detected value (preferably the minimum value) of the pressure sensor 95 such that the particle increment (ΔN) does not cause a problem for each processing condition. Then, write the obtained detected value of the pressure sensor 95 in each time interval of the processing recipe. The control device 4 performs feedback control on the purge gas supply mechanism 94 so that the detected value of the pressure sensor 95 described in the processing recipe stored in the storage unit 19 is realized.

[0088] <Operation Example 2> As shown in the graph of FIG. 5, there is a correlation between the purge gas discharge flow rate B and the pressure P3. It is obvious that there is a positive correlation between the purge gas discharge flow rate B and the pressure P0 in the space S0 below the wafer, and as described above, there is a positive correlation between the pressure P3 and the pressure P1 (or the pressure P2). The condition that the pressure P0 ≧ the pressure P1 (Condition 1) is one of the conditions for preventing the particle increment (ΔN) from causing a problem. Therefore, first, calculate an estimated value of the pressure P1 from the actually measured pressure P3 based on the known relationship between the pressure P3 and the pressure P1. Then, the purge gas supply mechanism 94 may be feedback-controlled so that the estimated value of the pressure P1 and the pressure P0 directly measured by the pressure sensor 95 satisfy the above Condition 1. When it is also necessary to satisfy the above-described Condition 2 (the pressure P0 ≧ the pressure PC), the purge gas supply mechanism 94 can be feedback-controlled in the same way of thinking.

[0089] In the above case, it is necessary to provide a pressure sensor (not shown) for actually measuring the pressure P3 and a pressure sensor (not shown) for actually measuring the pressure P0. If it is necessary to satisfy both Condition 1 and Condition 2 at the same time, the purge gas supply mechanism 94 can be feedback-controlled so that the pressure P0 satisfies the condition of being equal to or higher than the larger pressure (P1 or PC) obtained by comparing the pressure P1 and the pressure PC.

[0090] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The above embodiments may be omitted, substituted, or changed in various forms without departing from the scope and gist of the appended claims.

[0091] Also, in the liquid processing where the peripheral portion of the lower surface (back surface) of the substrate is the object to be processed, by using the technology described in the above embodiments, particles in the central portion of the lower surface of the substrate can be reduced. Thus, when the processing liquid is supplied from the nozzle to at least the peripheral portion of the lower surface of the substrate, in order to prevent the intrusion of the processing liquid into the shaft 317 or the purge gas supply pipe 91, it is preferable to constantly discharge a small amount of purge gas from the purge gas supply pipe 91.

[0092] The substrate is not limited to a semiconductor wafer, and may be a substrate made of other materials such as glass and ceramic.

Explanation of Reference Numerals

[0093] W Substrate (Semiconductor Wafer) 4 Control Unit (Control Device) 31 Substrate Holding Unit 311 Base Member (Base Plate) 312 Holding Member (Chuck Unit) 33 Rotation Driving Unit 41 - 43 Processing Liquid Nozzles 50 Liquid Receiving Cup 55 Exhaust Passage (Cup Exhaust Passage) 91 Purge Gas Nozzle (Purge Gas Supply Pipe) 943 Purge Gas Flow Control Device

Claims

1. A substrate processing apparatus, comprising: a disk-shaped base member; and a plurality of holding members provided at a peripheral edge of the base member for holding a substrate such that the substrate is spaced upward from the base member, the substrate holding unit holding the substrate in a horizontal posture; a rotation driving unit that rotationally drives the substrate holding unit around a vertical axis; a processing liquid nozzle that supplies a processing liquid to the substrate held by the substrate holding unit; a liquid receiving cup provided around the substrate holding unit for receiving the processing liquid scattered from the substrate held and rotated by the substrate holding unit; a cup exhaust passage having one end connected to an exhaust port of the liquid receiving cup and the other end connected to a negative pressure generating source for sucking an atmosphere in the liquid receiving cup; a purge gas nozzle that discharges a purge gas into a substrate lower space formed between a lower surface of the substrate held by the substrate holding unit and an upper surface of the base member; a purge gas flow rate control device that controls a flow rate of the purge gas discharged from the purge gas nozzle; a control unit that controls at least an operation of the purge gas flow rate control device; and comprising: the control unit controls an operation of the purge gas flow rate control device such that the purge gas is discharged into the substrate lower space from the purge gas nozzle at a flow rate that cancels a negative pressure generated in the substrate lower space as the substrate holding unit holding the substrate rotates; the control unit stores a table or a function showing a relationship between at least one processing parameter defined in advance in a processing recipe other than the flow rate of the purge gas and a flow rate of the purge gas necessary for canceling the negative pressure; the control unit determines the flow rate of the purge gas based on the table or the function, and controls the purge gas flow rate control device such that the purge gas is discharged from the purge gas nozzle at the determined flow rate of the purge gas; the at least one processing parameter includes: a rotation speed of the substrate holding unit; at least one of a flow rate of exhaust gas through the cup exhaust passage, a pressure in the cup exhaust passage, and an opening degree of a valve that determines the flow rate of the exhaust gas; A substrate processing apparatus.

2. A substrate processing apparatus, comprising: a disk-shaped base member; and a plurality of holding members provided at a peripheral edge of the base member for holding a substrate such that the substrate is spaced upward from the base member, the substrate holding unit holding the substrate in a horizontal posture; a rotation driving unit that rotationally drives the substrate holding unit around a vertical axis; A processing liquid nozzle for supplying a processing liquid to the substrate held by the substrate holding unit; A liquid receiving cup provided around the substrate holding unit for receiving the processing liquid scattered from the substrate held and rotated by the substrate holding unit, wherein at least two switchable flow paths are formed inside the liquid receiving cup; the liquid receiving cup; A cup exhaust passage for sucking the atmosphere inside the liquid receiving cup, one end of which is connected to the exhaust port of the liquid receiving cup and the other end of which is connected to a negative pressure generation source; A purge gas nozzle for discharging a purge gas into the space below the substrate formed between the lower surface of the substrate held by the substrate holding unit and the upper surface of the base member; A purge gas flow rate control device for controlling the flow rate of the purge gas discharged from the purge gas nozzle; A control unit for controlling at least the operation of the purge gas flow rate control device; Comprising; The control unit controls the operation of the purge gas flow rate control device so that the purge gas is discharged into the space below the substrate from the purge gas nozzle at a flow rate that cancels the negative pressure generated in the space below the substrate as the substrate holding unit holding the substrate rotates; The control unit stores a table or function showing the relationship between at least one processing parameter defined in advance in a processing recipe other than the flow rate of the purge gas and the flow rate of the purge gas required to cancel the negative pressure; The control unit determines the flow rate of the purge gas based on the table or the function, and controls the purge gas flow rate control device so that the purge gas is discharged from the purge gas nozzle at the determined flow rate of the purge gas; The at least one processing parameter includes; The rotation speed of the substrate holding unit; A parameter for determining the flow path used among the at least two flow paths of the liquid receiving cup; A substrate processing apparatus.

3. A substrate processing apparatus, A disk-shaped base member and a plurality of holding members provided at the peripheral edge of the base member for holding the substrate so that the substrate is spaced above the base member, comprising a substrate holding unit for holding the substrate in a horizontal posture; A rotation driving unit for rotationally driving the substrate holding unit around a vertical axis; A processing liquid nozzle for supplying a processing liquid to the substrate held by the substrate holding unit; A liquid receiving cup provided around the substrate holding unit for receiving the processing liquid scattered from the substrate held and rotated by the substrate holding unit; A cup exhaust passage that sucks the atmosphere in the liquid receiving cup, with one end connected to the exhaust port of the liquid receiving cup and the other end connected to a negative pressure generation source; A purge gas nozzle that discharges a purge gas into a substrate lower space formed between the lower surface of the substrate held by the substrate holding portion and the upper surface of the base member; A purge gas flow rate control device that controls the flow rate of the purge gas discharged from the purge gas nozzle; A control unit that controls at least the operation of the purge gas flow rate control device; Comprising; The control unit controls the operation of the purge gas flow rate control device so that the purge gas is discharged into the substrate lower space from the purge gas nozzle at a flow rate that cancels out the negative pressure generated in the substrate lower space as the substrate holding portion holding the substrate rotates; The substrate processing apparatus further includes a pressure sensor that detects the pressure in the substrate lower space, and the control unit determines the flow rate of the purge gas that can cancel out the negative pressure generated in the substrate lower space based on at least the detected pressure by the pressure sensor, and controls the purge gas flow rate control device so that the purge gas is discharged from the purge gas nozzle at the determined flow rate of the purge gas.

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