JP2015103608A - Substrate cleaning device and substrate processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate cleaning device which reduces the size of droplets of a binary fluid and thereby improves substrate cleaning effect.SOLUTION: A substrate cleaning device includes: a binary fluid nozzle 42 which supplies binary fluid jet-flow to a surface of a substrate; a gas supply line 55 which supplies a gas to a mixing chamber 61 in the binary fluid nozzle 42; a liquid supply line 57 which supplies a liquid to the binary fluid nozzle 42; and a droplet formation device 90 which forms droplets from the liquid supplied to the binary fluid nozzle 42 and supplies the droplets to the mixing chamber 61.

Description

  The present invention relates to a substrate cleaning apparatus for cleaning a substrate by supplying a two-fluid jet composed of a gas and a liquid to a substrate such as a wafer, and in particular, cleaning the substrate by supplying the two-fluid jet to the surface of a polished substrate. The present invention relates to a substrate cleaning apparatus. The substrate cleaning apparatus of the present invention can be applied to cleaning not only a wafer having a diameter of 300 mm but also a wafer having a diameter of 450 mm, and further, a flat panel manufacturing process, an image sensor manufacturing process such as CMOS and CCD, and a magnetic film manufacturing process of MRAM. It is also possible to apply it.

  With the recent miniaturization of semiconductor devices, various material films having different physical properties are formed on a substrate and the material films are processed. In particular, in a damascene wiring formation process in which a wiring groove formed in an insulating film is filled with metal, excess metal is polished and removed by a substrate polishing apparatus after the metal film is formed. Various films such as a metal film, a barrier film, and an insulating film exist on the surface of the substrate after polishing. In these films exposed on the substrate surface, there are residues such as slurry and polishing debris used in polishing. In order to remove such residues, the polished substrate is transported to a substrate cleaning apparatus, and the substrate surface is cleaned.

  If the surface of the substrate is not sufficiently cleaned, problems such as current leakage due to residue and poor adhesion will occur. Therefore, in the manufacture of semiconductor devices, the cleaning of the substrate is an important process for improving the yield of products.

  2. Description of the Related Art As a device for cleaning a substrate, a two-fluid cleaning device that supplies a two-fluid jet composed of a mixed fluid of gas and liquid to the surface of the substrate is known. As shown in FIG. 17, this two-fluid cleaning device supplies a two-fluid jet from the two-fluid nozzle 200 to the surface of the substrate W while moving the two-fluid nozzle 200 in parallel with the surface of the substrate W. Remove existing particles such as abrasive grains and polishing debris.

No. 2005-12197 2013-89797 gazette

  However, as shown in FIG. 18, the droplets forming the two-fluid jet are usually several tens of μm in size, whereas the minute particles on the substrate W are 100 nm or less in size. For this reason, as shown in FIG. 19, the droplets cannot enter recesses (for example, pattern steps or scratches) formed on the surface of the substrate, and can remove minute particles present in these recesses. could not.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a substrate cleaning apparatus capable of improving the substrate cleaning effect by making the two-fluid droplets smaller. . Moreover, an object of this invention is to provide the substrate processing apparatus provided with such a substrate cleaning apparatus.

  In order to achieve the above-described object, one embodiment of the present invention includes a substrate holding unit that holds a substrate, a two-fluid nozzle that supplies a two-fluid jet to the surface of the substrate, and a mixing chamber in the two-fluid nozzle. A gas supply line for supplying gas, a liquid supply line for supplying liquid into the two-fluid nozzle, and droplets are formed from the liquid supplied into the two-fluid nozzle, and the droplets are supplied to the mixing chamber. And a droplet forming apparatus for cleaning the substrate.

  In a preferred aspect of the present invention, the droplet forming apparatus is connected to the liquid supply line and communicates with the mixing chamber, a liquid supply valve that opens and closes a liquid flow path of the liquid supply line, A liquid suction line that sucks the liquid flowing through the liquid transfer pipe, a liquid suction valve that opens and closes a liquid flow path of the liquid suction line, and a valve control unit that alternately opens and closes the liquid supply valve and the liquid suction valve. It is characterized by providing.

In a preferred aspect of the present invention, the droplet forming apparatus includes a liquid chamber communicating with the liquid supply line, and a piezoelectric element that extrudes the liquid in the liquid chamber to form the droplet. .
In a preferred aspect of the present invention, the two-fluid nozzle has a gas chamber that guides the gas from the gas supply line to the mixing chamber, and a droplet discharge port of the droplet forming device is provided in the gas chamber. It is characterized by being surrounded.
In a preferred aspect of the present invention, the droplet forming apparatus includes a flange protruding outward from the droplet discharge port.
In a preferred aspect of the present invention, an ultrasonic transducer that vibrates the liquid is provided.

  Another aspect of the present invention is a substrate processing apparatus comprising a polishing unit for polishing a substrate and the substrate cleaning apparatus for cleaning the substrate polished by the polishing unit.

  According to the present invention, the droplets are crushed by the air flow in the mixing chamber to form minute droplets. The minute droplets easily enter a recess formed on the surface of the substrate, and remove particles present in the recess. Therefore, the substrate cleaning effect can be improved.

It is a top view which shows the whole structure of the substrate processing apparatus provided with the substrate cleaning apparatus which concerns on embodiment of this invention. It is a perspective view which shows the board | substrate cleaning apparatus which concerns on embodiment of this invention currently used for the 2nd cleaning unit. It is a schematic diagram which shows one Embodiment of the structure of a board | substrate cleaning apparatus. It is a graph which shows the open / close state of a liquid supply valve and a liquid suction valve. 5 is a graph showing the flow rate of liquid when the liquid supply valve and the liquid suction valve are periodically opened and closed at the timing shown in FIG. It is a graph which shows the flow volume of the liquid when a liquid supply valve is opened and closed periodically in the state which closed the liquid suction valve. It is a schematic diagram which shows the two-fluid jet which collides with the surface of a wafer. It is a schematic diagram which shows other embodiment of the structure of a board | substrate washing | cleaning apparatus. It is a longitudinal cross-sectional view of a piezo injector. It is a bottom view of a piezo injector. FIG. 10 is an enlarged view showing the liquid chamber and the piezoelectric element shown in FIG. 9. It is a figure which shows a state when a voltage is applied to the piezoelectric element shown in FIG. It is a figure which shows the flange formed in the lower end of a gas transfer pipe. It is a figure which shows the flange formed in the lower end of a piezo injector. It is a figure which shows the ultrasonic transducer | vibrator provided in the gas transfer pipe. It is a figure which shows the ultrasonic transducer | vibrator provided in the dispersion | distribution flow path in a piezo injector. It is a schematic diagram which shows the conventional two fluid washing | cleaning apparatus. It is a schematic diagram which shows the droplet of two fluids. It is a schematic diagram which shows the droplet which collided with the substrate surface.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing an overall configuration of a substrate processing apparatus including a substrate cleaning apparatus according to an embodiment of the present invention. As shown in FIG. 1, the substrate processing apparatus includes a substantially rectangular housing 10 and a load port 12 on which a substrate cassette that accommodates a large number of wafers and other substrates is placed. The load port 12 is disposed adjacent to the housing 10. The load port 12 can be mounted with an open cassette, a SMIF (Standard Manufacturing Interface) pod, or a FOUP (Front Opening Unified Pod). SMIF and FOUP are sealed containers that can maintain an environment independent of the external space by accommodating a substrate cassette inside and covering with a partition wall.

  Inside the housing 10, a plurality of (four in this embodiment) polishing units 14a to 14d, a first cleaning unit 16 and a second cleaning unit 18 for cleaning the substrate after polishing, and a substrate after cleaning are dried. A drying unit 20 is accommodated. The polishing units 14a to 14d are arranged along the longitudinal direction of the substrate processing apparatus, and the cleaning units 16, 18 and the drying unit 20 are also arranged along the longitudinal direction of the substrate processing apparatus.

  In a region surrounded by the load port 12, the polishing unit 14a, and the drying unit 20, a first substrate transfer robot 22 is disposed, and a substrate transfer unit 24 is disposed in parallel with the polishing units 14a to 14d. The first substrate transfer robot 22 receives the substrate before polishing from the load port 12 and passes it to the substrate transfer unit 24, and receives the dried substrate from the drying unit 20 and returns it to the load port 12. The substrate transport unit 24 transports the substrate received from the first substrate transport robot 22 and delivers the substrate to and from each of the polishing units 14a to 14d. Each polishing unit polishes the surface of a substrate by bringing a substrate such as a wafer into sliding contact with the polishing surface while supplying a polishing liquid (slurry) to the polishing surface.

  A second substrate transport robot 26 is disposed between the first cleaning unit 16 and the second cleaning unit 18 to transport the substrate between the cleaning units 16 and 18 and the substrate transport unit 24, and the second cleaning is performed. A third substrate transport robot 28 is disposed between the unit 18 and the drying unit 20 to transport the substrate between the units 18 and 20. Further, an operation control unit 30 that controls the movement of each unit of the substrate processing apparatus is disposed inside the housing 10.

  As the first cleaning unit 16, there is used a substrate cleaning apparatus that cleans a substrate by rubbing a roll sponge on both the front and back surfaces of the substrate in the presence of a chemical solution. As the second cleaning unit 18, a two-fluid type substrate cleaning apparatus according to an embodiment of the present invention is used. Further, as the drying unit 20, a spin drying apparatus is used that dries the substrate by holding the substrate, ejecting IPA vapor from a moving nozzle to dry the substrate, and rotating the substrate at a high speed.

  The substrate is polished by at least one of the polishing units 14a to 14d. The polished substrate is cleaned by the first cleaning unit 16 and the second cleaning unit 18, and the cleaned substrate is dried by the drying unit 20.

  FIG. 2 is a perspective view showing the substrate cleaning apparatus according to the embodiment of the present invention used in the second cleaning unit 18. As shown in FIG. 2, the substrate cleaning apparatus includes a substrate holding unit 41 that horizontally holds and rotates a wafer W, which is an example of a substrate, and a two-fluid nozzle 42 that supplies a two-fluid jet to the upper surface of the wafer W. And a nozzle arm 44 for holding the two-fluid nozzle 42. A gas supply line 55, a liquid supply line 57, and a liquid suction line 58 are connected to the two-fluid nozzle 42.

  The substrate holder 41 includes a plurality of (four in FIG. 2) chucks 45 that hold the peripheral edge of the wafer W, and a motor 48 connected to the chucks 45. The chuck 45 holds the wafer W horizontally, and in this state, the wafer W is rotated around its central axis by a motor 48.

  The two-fluid nozzle 42 is disposed above the wafer W. A two-fluid nozzle 42 is attached to one end of the nozzle arm 44, and a turning shaft 50 is connected to the other end of the nozzle arm 44. The two-fluid nozzle 42 is connected to the nozzle moving mechanism 51 via the nozzle arm 44 and the turning shaft 50. More specifically, a nozzle moving mechanism 51 that turns the nozzle arm 44 is connected to the turning shaft 50. The nozzle moving mechanism 51 turns the nozzle arm 44 in a plane parallel to the wafer W by rotating the turning shaft 50 by a predetermined angle. The two-fluid nozzle 42 supported by the nozzle arm 44 moves in the radial direction of the wafer W as the nozzle arm 44 turns.

  The nozzle moving mechanism 51 is connected to a nozzle lifting / lowering mechanism 52 that moves the turning shaft 50 up and down, so that the two-fluid nozzle 42 can move up and down relatively with respect to the wafer W. . The nozzle lifting mechanism 52 functions as a distance adjusting mechanism that changes the distance between the two-fluid nozzle 42 and the surface of the wafer W.

  The wafer W is cleaned as follows. First, the substrate holder 41 rotates the wafer W around its central axis. In this state, the two-fluid nozzle 42 supplies a two-fluid jet to the upper surface of the wafer W, and further moves in the radial direction of the wafer W. The upper surface of the wafer W is cleaned by a two-fluid jet.

  FIG. 3 is a schematic diagram showing an embodiment of the structure of the substrate cleaning apparatus. As shown in FIG. 3, the two-fluid nozzle 42 includes a gas supply line 55 that supplies gas to the mixing chamber 61 through a gas chamber 60 formed therein, and a gas transfer pipe 77 that communicates with the mixing chamber 61. A liquid supply line 57 for supplying a liquid (for example, pure water) and a liquid suction line 58 for sucking the liquid flowing through the gas transfer pipe 77 are connected.

  The gas chamber 60, the mixing chamber 61, and the gas transfer pipe 77 are disposed in the two-fluid nozzle 42. The gas transfer pipe 77 is surrounded by an outer cylinder 78, and a gas chamber 60 is formed between the gas transfer pipe 77 and the outer cylinder 78. The mixing chamber 61 is formed inside the outer cylinder 78 and is located below the gas transfer pipe 77 and the gas chamber 60. The gas chamber 60 communicates with the mixing chamber 61, and the gas from the gas supply line 55 is guided to the mixing chamber 61 through the gas chamber 60.

  A filter 72 is provided in the gas supply line 55. A gas (for example, an inert gas such as nitrogen gas) flowing through the gas supply line 55 passes through the filter 72 and flows into the gas chamber 60 of the two-fluid nozzle 42.

  The liquid supply line 57 is provided with a liquid supply valve 81 for opening and closing the liquid flow path, and the liquid suction line 58 is provided with a liquid suction valve 82 for opening and closing the liquid flow path. As the liquid supply valve 81 and the liquid suction valve 82, a flow rate control valve (for example, a mass flow controller), an air operation valve, an on-off valve (ON-OFF valve), or the like is used.

  One end of the liquid suction line 58 is connected to the side surface of the gas transfer pipe 77. That is, the gas transfer pipe 77 has a liquid suction port 79 on its side surface, and the liquid suction line 58 is connected to the liquid suction port 79. The other end of the liquid suction line 58 is connected to a liquid suction pump 88. The liquid supply line 57 is connected to the upper end opening of the gas transfer pipe 77. The liquid supply valve 81 and the liquid suction valve 82 are connected to the valve control unit 75, and the opening / closing operations of the liquid supply valve 81 and the liquid suction valve 82 are controlled by the valve control unit 75. More specifically, the liquid supply valve 81 and the liquid suction valve 82 are opened and closed at a predetermined cycle so that the supply of the liquid to the gas transfer pipe 77 and the suction of the liquid from the gas transfer pipe 77 are alternately repeated. Is repeated.

  FIG. 4 is a graph showing the open / closed state of the liquid supply valve 81 and the liquid suction valve 82. In FIG. 4, the vertical axis indicates whether the liquid supply valve 81 and the liquid suction valve 82 are in the open state or the closed state, and the horizontal axis indicates time. As can be seen from FIG. 4, the liquid supply valve 81 and the liquid suction valve 82 repeat opening and closing operations at the same cycle, but the opening and closing state of the liquid suction valve 82 is opposite to the opening and closing state of the liquid supply valve 81. That is, the liquid suction valve 82 is closed at the same time as the liquid supply valve 81 is opened, and the liquid suction valve 82 is opened at the same time as the liquid supply valve 81 is closed.

  As described above, the liquid supply valve 81 and the liquid suction valve 82 are alternately opened and closed in the same cycle, whereby the supply of the liquid to the gas transfer pipe 77 and the suction of the liquid from the gas transfer pipe 77 are alternately performed. The opening / closing operation of the liquid supply valve 81 and the liquid suction valve 82 is controlled by the valve control unit 75. As shown in FIG. 4, the valve controller 75 opens and closes the liquid supply valve 81 and the liquid suction valve 82 alternately in the same cycle.

  FIG. 5 is a graph showing the flow rate of the liquid when the liquid supply valve 81 and the liquid suction valve 82 are periodically opened and closed at the timing shown in FIG. Since the supply and suction of the liquid are performed alternately, the flow rate of the liquid flowing through the gas transfer pipe 77 varies greatly as shown in FIG. As a result, the liquid is discharged as droplets from the droplet discharge port 80 at the lower end of the gas transfer tube 77. The droplets are supplied to the mixing chamber 61 formed below the gas transfer pipe 77.

  FIG. 6 is a graph showing the liquid flow rate when the liquid supply valve 81 is periodically opened and closed with the liquid suction valve 82 closed. As shown in FIG. 6, when only the liquid supply valve 81 is opened and closed, the flow rate of the liquid flowing through the gas transfer pipe 77 does not vary greatly. As can be seen from the comparison between the graph of FIG. 5 and the graph of FIG. 6, the liquid flowing through the gas transfer pipe 77 can be converted into droplets by alternately repeating the supply and suction of the liquid.

  The gas chamber 60 is formed so as to surround the gas transfer pipe 77, and the droplet discharge port 80 of the gas transfer pipe 77 is surrounded by the gas chamber 60. In the gas chamber 60, an air flow that travels toward the mixing chamber 61 is formed. The liquid droplets discharged from the liquid droplet discharge port 80 are crushed by the air current in the mixing chamber 61 and become finer liquid droplets. Such minute droplets and gas are mixed in the mixing chamber 61 to form a two-fluid jet.

  FIG. 7 is a schematic diagram showing a two-fluid jet that collides with the surface of the wafer W. FIG. As shown in FIG. 7, minute droplets constituting the two-fluid jet flow enter minute recesses (for example, pattern steps or scratches) formed on the surface of the wafer W, and 100 nm existing in these recesses. The following minute particles can be removed.

  In the present embodiment, the droplet forming device 90 is connected to the liquid supply line 57 and communicates with the mixing chamber 61, the liquid supply valve 81 that opens and closes the liquid flow path of the liquid supply line 57, and the gas A liquid suction line 58 that sucks the liquid flowing through the transfer pipe 77, a liquid suction valve 82 that opens and closes the liquid flow path of the liquid suction line 58, and a valve control unit 75 that alternately opens and closes the liquid supply valve 81 and the liquid suction valve 82. It consists of.

  FIG. 8 is a schematic view showing another embodiment of the structure of the substrate cleaning apparatus. The configuration of the present embodiment that is not specifically described is the same as the configuration of the embodiment shown in FIG.

  As shown in FIG. 8, the droplet forming apparatus 90 of this embodiment includes a piezo injector (piezo-type ejecting apparatus) 95. The piezo injector 95 is disposed in the two-fluid nozzle 42. The gas chamber 60 is formed around the piezo injector 95, and the mixing chamber 61 is located below the piezo injector 95. The piezo injector 95 is connected to a liquid supply line 57, and the liquid is supplied through the liquid supply line 57. The liquid is converted into droplets by the piezo injector 95, and these droplets are supplied to the mixing chamber 61. In the present embodiment, the liquid suction line 58, the liquid suction valve 82, and the valve control unit 75 described above are not provided. The liquid supply valve 81 may not be provided.

  FIG. 9 is a longitudinal sectional view of the piezo injector 95, and FIG. 10 is a bottom view of the piezo injector 95. The piezo injector 95 includes a plurality of liquid chambers 97, a plurality of piezo elements 98 adjacent to the liquid chambers 97, and a dispersion channel 99 connected to the plurality of liquid chambers 97. The plurality of liquid chambers 97 communicate with the liquid supply line 57 through the dispersion channel 99. Further, the plurality of liquid chambers 97 communicate with the plurality of droplet discharge ports 80, respectively. These droplet discharge ports 80 are formed on the lower surface of the piezo injector 95. The droplet discharge port 80 is surrounded by the gas chamber 60. A power source (not shown) is connected to each piezo element 98 so that a voltage is periodically applied to the piezo elements 98.

  11 is an enlarged view showing the liquid chamber 97 and the piezo element 98 shown in FIG. 9, and FIG. 12 is a view showing a state when a voltage is applied to the piezo element 98 shown in FIG. The piezo element 98 is in contact with the liquid in the liquid chamber 97. When a voltage is applied to the piezo element 98, the piezo element 98 is deformed as shown in FIG. As a result, the liquid filling the liquid chamber 97 is pushed out to the deformed piezo element 98 and discharged as a droplet from the droplet discharge port 80.

  A voltage is periodically applied to the piezo element 98, and the piezo element 98 continuously ejects droplets into the mixing chamber 61. The droplets are crushed by the air flow in the mixing chamber 61 and become further fine droplets. Such minute droplets and gas are mixed in the mixing chamber 61 to form a two-fluid jet. As shown in FIG. 7, minute droplets constituting the two-fluid jet flow enter minute recesses (for example, pattern steps or scratches) formed on the surface of the wafer, and are 100 nm or less existing in these recesses. The minute particles can be removed.

  In the above-described embodiment, droplets are supplied to the mixing chamber 61 and become smaller droplets by collision with the airflow. In order to promote the collision between the droplet and the airflow, it is preferable to cause a turbulent gas flow in the mixing chamber 61. Specifically, as shown in FIGS. 13 and 14, the droplet forming apparatus 90 may have a flange 105 that protrudes outward from the droplet discharge port 80. In the example shown in FIG. 13, the flange 105 is formed at the lower end of the gas transfer pipe 77, and in the example shown in FIG. 14, the flange 105 is formed at the lower end of the piezo injector 95.

  The flange 105 is located in the gas chamber 60. When the air current passes over the flange 105, the air current is disturbed to form an inward vortex. Such vortex flows collide with the liquid droplets discharged from the liquid droplet discharge port 80 and make the liquid droplets smaller. In order to generate a stronger gas vortex, the gas flow rate is preferably equal to or higher than the speed of sound.

  In order to further improve the cleaning effect of the two-fluid jet, as shown in FIGS. 15 and 16, an ultrasonic vibrator 107 that vibrates the liquid before forming a droplet may be provided. In the example shown in FIG. 15, the ultrasonic transducer 107 is provided so as to surround a part of the gas transfer pipe 77, and in the example shown in FIG. 16, the ultrasonic transducer 107 is arranged in the dispersion flow path 99 in the piezo injector 95. It is provided so as to surround a part. The ultrasonic vibrator 107 may be provided in the liquid supply line 57. The vibration frequency of the ultrasonic vibrator 107 is preferably several tens Hz to several MHz. Furthermore, a plurality of ultrasonic transducers 107 having different vibration frequencies may be provided along the gas transfer pipe 77 or the dispersion flow path 99. Thus, particles of different sizes can be removed from the wafer W by vibrating the liquid at different frequencies. The ultrasonic vibrator 107 can vibrate the liquid droplets ejected from the liquid droplet ejection port 80, thereby removing particles on the wafer more effectively.

  The embodiment described above is described for the purpose of enabling the person having ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Accordingly, the present invention is not limited to the described embodiments, but is to be construed in the widest scope according to the technical idea defined by the claims.

10 Housing 12 Load Ports 14a to 14d Polishing Unit 16 First Cleaning Unit 18 Second Cleaning Unit 20 Drying Unit 22 First Substrate Transfer Robot 24 Substrate Transfer Unit 26 Second Substrate Transfer Robot 28 Third Substrate Transfer Robot 30 Operation Control Unit 41 Substrate holder 42 Two-fluid nozzle 44 Nozzle arm 45 Chuck 48 Motor 50 Rotating shaft 51 Nozzle moving mechanism 52 Nozzle lifting mechanism (distance adjusting mechanism)
55 Gas supply line 57 Liquid supply line 58 Liquid suction line 60 Gas chamber 61 Mixing chamber 72 Filter 75 Valve controller 77 Gas transfer pipe 78 Outer cylinder 79 Liquid suction port 80 Liquid discharge port 81 Liquid supply valve 82 Liquid suction valve 88 Suction Liquid pump 90 Droplet forming device 95 Piezo injector 97 Liquid chamber 98 Piezo element 99 Dispersion flow path 105 Flange 107 Ultrasonic vibrator

Claims (7)

A substrate holder for holding the substrate;
A two-fluid nozzle for supplying a two-fluid jet to the surface of the substrate;
A gas supply line for supplying gas to the mixing chamber in the two-fluid nozzle;
A liquid supply line for supplying liquid to the two-fluid nozzle;
A substrate cleaning apparatus, comprising: a droplet forming device that forms droplets from the liquid supplied to the two-fluid nozzle and supplies the droplets to the mixing chamber. The droplet forming apparatus comprises:
A liquid transfer pipe connected to the liquid supply line and communicating with the mixing chamber;
A liquid supply valve for opening and closing a liquid flow path of the liquid supply line;
A liquid suction line for sucking the liquid flowing through the liquid transfer pipe;
A liquid suction valve for opening and closing the liquid flow path of the liquid suction line;
The substrate cleaning apparatus according to claim 1, further comprising a valve control unit that alternately opens and closes the liquid supply valve and the liquid suction valve. The droplet forming apparatus comprises:
A liquid chamber communicating with the liquid supply line;
The substrate cleaning apparatus according to claim 1, further comprising: a piezoelectric element that extrudes the liquid in the liquid chamber to form the droplet. The two-fluid nozzle has a gas chamber that guides the gas from the gas supply line to the mixing chamber,
4. The substrate cleaning apparatus according to claim 1, wherein a droplet discharge port of the droplet forming apparatus is surrounded by the gas chamber. 5.   5. The substrate cleaning apparatus according to claim 4, wherein the droplet forming device has a flange protruding outward from the droplet discharge port.   The substrate cleaning apparatus according to claim 1, further comprising an ultrasonic vibrator that vibrates the liquid. A polishing unit for polishing a substrate;
A substrate processing apparatus comprising the substrate cleaning apparatus according to claim 1, wherein the substrate polished by the polishing unit is cleaned.

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