TW201438824A - Wafer cleaning method and system thereof - Google Patents

Abstract

The present invention provides a wafer cleaning method and system thereof. The wafer cleaning system comprises a processing head, a liquid suction unit, a conveying unit, a liquid supply unit, a liquid drainage unit and an electric control unit. The processing head is configured with a plurality of nozzles and formed with a gap. The liquid suction unit comprises an external water circulation pipe and an internal water circulation pipe formed on the upper and lower processing heads, and a tank communicating with the pipes. The conveying unit employs a carrier to move a wafer approaching or away from the processing head. The liquid supply unit employs a first and a fourth input pipe to connect to the nozzle of the upper processing head, and a second and a third input pipe to connect to the nozzle of the lower processing head. The liquid drainage unit is configured with the first to fourth switching valves respectively on the first to fourth input pipes, wherein the first to fourth switching valves are communicated with the tank or the recycle tank respectively through the first to fourth drainage pipes. The electric control unit may switch the liquid flowing direction of the first to fourth switching valves according to an input signal.

Description

Wafer cleaning method and system thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a wafer cleaning system and method thereof, and more particularly to a cleaning system and method for a silicon wafer semiconductor that utilizes a switching valve to timely switch a liquid flow output to a processing head to a drainage system.

The wafer cleaning system currently used in the 矽 wafer cleaning process is as shown in FIG. 1 , and the wafer 17 to be cleaned is passed through a processing head 10 disposed on the machine head 10 and a lower processing head 12 . The gap between the first and second wafers 17 receives the chemical liquid 13, the deionized water 14 and the drying fluid 15 which are normally ejected in the gap, and is sucked up by the return water pipe 18 provided on the process head 10. The fluid (liquid) is inside the tank.

When the wafer is cleaned, the upper processing head 11 and the lower processing head 12 simultaneously supply 3000 ml/m, 2000 ml/m of the chemical liquid 13 and 3000 ml/m, 2000 ml/m of deionized water 14 at the same time. The small suction holes of the upper process head 11 and the lower process head 12 of the return pipe 18 cannot absorb excess fluid (liquid) and cause liquid to remain on the wafer, resulting in backside wetting and drag marks (Exit mark) The residual liquid remaining on the surface of the wafer causes oxidation and over-etching of the wafer surface, resulting in the removal of the copper tin surface. In addition, in order to suck excess liquid (waste liquid) from the process head into the tank, a control valve is generally provided on the return pipe, and a pressure gauge component is arranged on the tank, when the control valve and the pressure gauge component are degraded. This will cause a larger amount of waste liquid to be absorbed into the tank, causing the wafer to become wet.

The object of the present invention is to provide a wafer cleaning system and a method thereof, wherein a liquid drainage unit controlled by an electronic control unit is added between the liquid supply unit and the cleaning processing head, so that the liquid supply unit can supply the cleaning processing head. To the degree of rationalization.

To achieve the above object, the wafer cleaning system of the present invention comprises: a process head having an upper processing head and a lower processing head, wherein the upper and lower processing heads respectively face each other with a corresponding surface and form a gap, each corresponding surface Configure multiple nozzles. a liquid suction unit comprising an external return pipe and an internal return pipe formed on the upper process head for pumping liquid, an external return pipe and an internal return pipe formed on the lower process head for pumping liquid, and A tank that communicates with the external return line and the internal return line and collects liquid. A transport unit is configured to apply a carrier to move the wafer closer to or away from the process head and to maintain the wafer surface relative to the corresponding surfaces. a liquid supply unit is connected to a part of the nozzles of the upper processing heads by a first input line, and is connected to a part of the nozzles of the lower processing heads by a second input line, and a third input tube The road is in communication with a portion of the nozzles of the upper processing heads, and is connected to a portion of the nozzles of the lower processing heads by a fourth input line. a liquid draining unit is provided with a first switching valve, a second switching valve and a third switching valve on the first input line, the second input line, the third input line and the fourth input line respectively And a fourth switching valve, the first switching valve, the second switching valve, the third switching valve and the fourth switching valve are respectively a first drainage line, a second drainage line, and a third drainage tube The road and the fourth drainage line communicate with the tank or communicate with a recovery tank. An electronic control unit switches the liquid flow directions of the first switching valve, the second switching valve, the third switching valve and the fourth switching valve according to different input signals.

In order to achieve the above object, a wafer cleaning method provided by the present invention includes: the carrier using the transport unit carries the wafer to travel in a first direction to enter the gap, and when the carrier is located at the first In the position, the distance sensing unit is triggered to generate the first signal; the electronic control unit switches the first switching valve, the second switching valve, the third switching valve and the fourth switching valve according to the first signal, Discharging the liquid in the liquid supply unit to the tank or the recovery tank; the electronic control unit actuates the first to the fourth liquid suction valve according to the first signal to respectively respectively belong to the section pipeline The liquid is sucked back into the drainage system; when the stage travels in a second direction opposite to the first direction to enter the gap, and when the stage is located in the second position, triggering the distance sensing unit to generate The second signal; the electronic control unit switches the first switching valve, the second switching valve, the third switching valve and the fourth switching valve according to the second signal to make the first to fourth input lines The liquid inside flows to the process head The electronic control unit is stopped and the second signal according to the first to the fourth back to the suction operation of the suction valve.

The invention is characterized in that the chemical liquid (such as sulfuric acid and hydrofluoric acid) and deionized water (DIW) used in the bypass (drainage) wafer cleaning process are used to solve the conventional chemical solution of the conventional machine. Caused by crystal back wet and drag mark defects. In addition, since the liquid ejecting amount of the present invention can be appropriately adjusted, it can solve the problem that the control valve on the return pipe and the pressure gauge component on the tank groove are degraded, so that a larger amount of waste liquid can be absorbed without returning to the tank groove, resulting in wafer generation. Wetting problem.

10‧‧‧Process head

11‧‧‧Upper head

12‧‧‧Next process head

13‧‧‧Chemical liquid

14‧‧‧Deionized water

15‧‧‧Drying fluid

16‧‧‧ barrel

17‧‧‧ Wafer

18‧‧‧return pipe

20‧‧‧ wafer

30‧‧‧Processing head

31‧‧‧Upper head

311‧‧‧ corresponding face

312‧‧‧ nozzle

32‧‧‧Down head

321‧‧‧ corresponding face

322‧‧‧Nozzles

33‧‧‧ gap

34‧‧‧Clean area

35‧‧‧washing area

36‧‧‧Blow dry area

40‧‧‧Liquid suction unit

41‧‧‧External return pipe

42‧‧‧Internal return line

43‧‧‧ barrel

50‧‧‧Conveying unit

51‧‧‧Loading station

52‧‧‧First direction

53‧‧‧second direction

60‧‧‧Liquid supply unit

61‧‧‧First input line

62‧‧‧Second input line

63‧‧‧ third input line

64‧‧‧fourth input line

70‧‧‧Liquid drainage unit

71‧‧‧First switching valve

711‧‧‧First drainage line

712‧‧‧First suction valve

72‧‧‧Second switching valve

721‧‧‧Second drainage line

722‧‧‧Second suction valve

73‧‧‧ Third switching valve

731‧‧‧ Third drainage line

732‧‧‧ Third suction valve

74‧‧‧fourth switching valve

741‧‧‧fourth drainage line

742‧‧‧fourth suction valve

75‧‧‧Drainage system

76‧‧‧Recycling tank

77‧‧‧Flow control valve

80‧‧‧Electronic control unit

81‧‧‧First solenoid valve

82‧‧‧Second solenoid valve

83‧‧‧The third solenoid valve

84‧‧‧fourth solenoid valve

90‧‧‧Distance sensing unit

91‧‧‧First signal

92‧‧‧second signal

A‧‧‧ first position

B‧‧‧second position

C‧‧‧virtual dividing line

D‧‧‧Chemical liquid

E‧‧‧Deionized water

F‧‧‧Drying fluid

X‧‧‧ path

Starting point of Xx‧‧

Xy‧‧‧ end point

Step S10~Step S60‧‧‧ Process Step

1 is a block diagram of a system of a prior art wafer cleaning system.

2 is a perspective view showing the cleaning operation of the wafer cleaning system of the present invention.

3 is a system block diagram of an embodiment of a wafer cleaning system of the present invention.

4 is a system block diagram of an embodiment of a wafer cleaning system of the present invention in which an aspiration valve is disposed in an input line.

5 is a system block diagram of an embodiment of a distance sensing unit of the wafer cleaning system of the present invention.

6 is a system block diagram showing a schematic operation of a processing head of the wafer cleaning system of the present invention in cooperation with a liquid drainage unit, a distance sensing unit, and an electronic control unit.

7 is a system block diagram showing a schematic operation of a process head of the wafer cleaning system of the present invention in cooperation with a distance sensing unit and a transport unit.

FIG. 8 is a flow chart showing the steps of the wafer cleaning method of the present invention.

The embodiment of the present invention will be described with reference to the drawings.

First, a schematic diagram of a cleaning operation of the wafer cleaning system of the present invention, a system block diagram of an embodiment of the wafer cleaning system of the present invention illustrated in FIG. 3, and a crystal of the present invention illustrated in FIG. A block diagram of an embodiment of a circular cleaning system in which an aspiration valve is placed in an input line. The wafer cleaning system in this embodiment includes a process head 30, a liquid suction unit 40, a transport unit 50, a liquid supply unit 60, a liquid drain unit 70, and an electronic control unit 80. The process head 30 includes an upper process head 31 and a lower process head 32. The upper and lower process heads (31, 32) are opposite each other with a corresponding surface (311, 321) and form a gap 33, each corresponding surface (311, 321). A plurality of nozzles (312, 322) are disposed on the substrate (as shown in FIG. 6). The liquid suction unit 40 includes an external return water line 41 and an internal return water line 42 respectively formed on the upper processing head 31 and the lower processing head 32 for sucking the liquid in the gap 33, and A tank tank 43 that communicates with the external return water line 41 and the internal return water line 42 and collects liquid. The transport unit 50 is configured to apply a loading table 51 to move the wafer 20 to be close to or away from the processing head 30, and to maintain the upper and lower surfaces of the wafer 20 relative to the corresponding surfaces (311, 321) during the moving process. The liquid supply unit 60 communicates with a portion of the nozzles 312 of the upper processing heads 31 via a first input line 61, and communicates with a portion of the nozzles 312 of the lower processing heads 32 via a second input line 62. A third input line 63 communicates with a portion of the nozzles 312 of the upper processing heads 31 and communicates with a portion of the nozzles 312 of the lower processing heads 32 via a fourth input line 64. The liquid supply unit 60, the liquid supplied to the first input line 61 and the third input line 63 is a chemical liquid D, and the liquid supplied to the second input line 62 and the fourth input line 64 is deionized water. E. The liquid draining unit 70 is provided with a first switching valve 71 and a second switching valve 72 on the first input line 61, the second input line 62, the third input line 63 and the fourth input line 64, respectively. a third switching valve 73 and a fourth switching valve 74, the first switching valve 71, the second switching valve 72, the third switching valve 73 and the fourth switching valve 74 are respectively a first drainage tube The road 711, the second drainage line 721, the third drainage line 731, and the fourth drainage line 741 communicate with the tank 43 or otherwise communicate with a recovery tank 76 to separate from the tank 43 for collecting waste liquid. . The electronic control unit 80 generates corresponding detection signals according to different positions of the input signals according to the sensed position of the load-bearing table 51, as described later, as follows: first to fourth solenoid valves (81, 82, 83) 84) switching the liquid flow direction of the first switching valve 71, the second switching valve 72, the third switching valve 73, and the fourth switching valve 74.

Please refer to Figure 5. In addition, in order to adjust the liquid supply amount of the liquid supply unit 60, in one embodiment, each of the first drainage line 711, the second drainage line 721, the third drainage line 731, and the fourth drainage line 741 Drainage tube A flow control valve 77 is provided to control the flow of liquid into the tank 43 or the recovery tank 76.

Referring to FIG. 5 , in an embodiment, a first liquid suction valve 712 , a second switching valve 72 , and the upper processing head 31 are disposed between the first switching valve 71 and the upper processing head 31 . A third liquid suction valve 722 is disposed between the second liquid suction valve 722, the third switching valve 73 and the lower processing head 32, and a fourth liquid suction is disposed between the fourth switching valve 74 and the lower processing head 32. The valve 742 is further connected to the drainage system 75 by the first to the fourth liquid suction valves (712, 722, 732, 742) to drain the returned liquid.

Please refer to FIG. 5 , which is a system block diagram of an embodiment of a distance sensing unit of the wafer cleaning system of the present invention, and a process head and a liquid drainage unit and a distance sensing unit of the wafer cleaning system of the present invention illustrated in FIG. 6 . FIG. 7 is a system block diagram showing the cooperative operation of the electronic control unit and the system block diagram of the processing head of the wafer cleaning system of the present invention and the distance sensing unit and the transport unit. In an embodiment, a distance sensing unit 90 can be further configured to detect the position of the carrying platform 51 and trigger the corresponding signal accordingly. Further, the distance sensing unit 90 detects that the loading station 51 is in a first position A, and triggers a first signal 91. The electronic control unit 80 uses the first electromagnetic valve 81 according to the first signal 91. The second electromagnetic valve 82, the third electromagnetic valve 83 and the fourth electromagnetic valve 84 switch the steering of the first switching valve 71, the second switching valve 72, the third switching valve 73 and the fourth switching valve 74 The liquid in the first to fourth input lines (61, 62, 63, 64) is respectively passed through the first drainage line 711, the second drainage line 721, the third drainage line 731, and the The fourth drainage line 741 flows to the tank 43 or the recovery tank 76, and simultaneously activates the first to fourth suction valves (712, 722, 732, 742), respectively sucking the liquid in the associated section pipeline back to the drainage system 75. The distance sensing unit 90 detects that the carrying platform 51 is located at a second When the position B is triggered, a second signal 92 is triggered, and the electronic control unit 80 switches the steering of the first to fourth switching valves (71, 72, 73, 74) according to the second signal 92 to make the first to fourth inputs. The liquid in the line (61, 62, 63, 64) flows to the process head 30 while stopping the suckback action of the first to fourth pipetting valves (712, 722, 732, 742).

Please refer to Figure 7 again. The corresponding surfaces (311, 321) of the upper and lower processing heads (31, 32) are sequentially divided into a cleaning area 34, a processing area 35, and a drying area 36 according to the order in which the wafer 20 enters the gap 33. The nozzle 322 connecting the first input line 61 and the nozzle 322 connecting the fourth input line 64 are located in the cleaning area 34, and the second input line 62 is connected to the nozzle 322 and connected to the third input tube. A nozzle 63 is located in the flushing zone 35, and a virtual dividing line C is defined in the flushing zone 35 adjacent to the flushing zone 35 and the blow-drying zone 36. The carrier 20 transports the wafer 20 to move. In the path X, when the end of the loading platform 51 is aligned with the virtual dividing line C, the loading platform 51 is located at the first position A, and the front end of the loading platform 51 is aligned with the virtual dividing line C, the loading platform 51 is located at the second position. B.

In the above embodiment, the process head 30 also includes the ejecting arrangement of the drying fluid F, and the arrangement thereof is the same as that of the prior art, and is not changed in the present invention, and therefore will not be described again.

Please refer to FIG. 8 for a flow chart of the steps of the wafer cleaning method of the present invention and FIG. 7 for a schematic diagram of the system of the wafer cleaning system of the present invention in cooperation with the distance sensing unit and the transport unit. The wafer cleaning method of the embodiment is applicable to the foregoing wafer cleaning system embodiment, and the wafer cleaning method comprises the following steps: Step S10, applying the loading platform 51 in the conveying unit 50 to carry the cleaning processing. Wafer 20, carrier 51 and wafer 20 along a first direction 52 proceeds to enter the gap 33, and when the carrier 51 is located at the first position A as set above, the distance sensing unit 90 is triggered to generate the first signal 91; and the electronic control unit is step S20 80, according to the triggering of the first signal 91, the steering switching of the first to fourth switching valves (71, 72, 73, 74) is performed, and the liquid in the liquid supply unit 60 is drained to the tank 43 or the Recycling the tank 76; in step S30, the electronic control unit 80 activates the first to the fourth liquid suction valves (712, 722, 732, 742) according to the generation of the first signal 91 to respectively suck the liquid in the pipeline of the section to which it belongs Returning the drainage system 75 to maintain the saturation tube in the tube to avoid contamination in the foreign material inlet pipe; in step S40, when the stage 51 travels in the second direction 53 (opposite the first direction 52), enters the gap 33, and when the carrying station 51 is located in the second position B, triggering the distance sensing unit 90 to generate the second signal 92; in step S50, the electronic control unit 80 switches according to the generation of the second signal 92. The first to fourth switching valves (71, 72, 73, 74) are turned to make the first to fourth input lines (61, 62, 63) The liquid in 64) flows to the process head 30; and in step S60, the electronic control unit 80 stops the suction operation of the first to fourth liquid suction valves (712, 722, 732, 742) according to the second signal 92.

In addition, in an embodiment, when the distance sensing unit 90 generates the first signal 91, the cleaning operation of the wafer cleaning system is interrupted, and the cleaning area 34 and the processing area 35 of the processing head 30 are stopped. Ejecting the liquid to close the water curtain of the gap 33, and when the distance sensing unit 90 generates the second signal 92, starting the cleaning operation of the wafer cleaning system, the cleaning area 34 of the processing head 30 and the The flushing zone 35 ejects liquid, causing the gap 33 to create a water curtain effect. Of course, as in the foregoing system embodiment, in the embodiment of the method, the liquid supply unit 60 is supplied to The liquid of the first input line 61 and the third input line 63 is a chemical liquid D, and the liquid supplied to the second input line 62 and the fourth input line 64 is deionized water E.

In summary, the present invention uses a chemical liquid such as sulfuric acid, hydrofluoric acid, and deionized water used in the flow-through wafer cleaning process to solve the problem of crystal back wetness and drag marks caused by residual chemical liquid in the conventional machine. problem. In addition, the liquid ejecting amount of the present invention can be appropriately adjusted to solve the problem that the control valve on the return pipe and the pressure gauge component on the tank groove are degraded, so that a larger amount of waste liquid is absorbed into the tank groove, resulting in wafer sticking. Wetting problem. .

The above-described technical means embodiments or examples are not intended to limit the scope of implementation of the invention. That is, the equivalent changes and modifications made in accordance with the scope of the patent application of the present invention or the scope of the invention are covered by the scope of the invention.

20‧‧‧ wafer

30‧‧‧Processing head

31‧‧‧Upper head

32‧‧‧Down head

33‧‧‧ gap

41‧‧‧External return pipe

42‧‧‧Internal return line

43‧‧‧ barrel

51‧‧‧Loading station

60‧‧‧Liquid supply unit

61‧‧‧First input line

62‧‧‧Second input line

63‧‧‧ third input line

64‧‧‧fourth input line

71‧‧‧First switching valve

711‧‧‧First drainage line

712‧‧‧First suction valve

72‧‧‧Second switching valve

721‧‧‧Second drainage line

722‧‧‧Second suction valve

73‧‧‧ Third switching valve

731‧‧‧ Third drainage line

732‧‧‧ Third suction valve

74‧‧‧fourth switching valve

741‧‧‧fourth drainage line

742‧‧‧fourth suction valve

75‧‧‧Drainage system

76‧‧‧Recycling tank

77‧‧‧Flow control valve

80‧‧‧Electronic control unit

81‧‧‧First solenoid valve

82‧‧‧Second solenoid valve

83‧‧‧The third solenoid valve

84‧‧‧fourth solenoid valve

90‧‧‧Distance sensing unit

91‧‧‧First signal

92‧‧‧second signal

D‧‧‧Chemical liquid

E‧‧‧Deionized water

F‧‧‧Drying fluid

Claims (11)

A wafer cleaning system comprising: a processing head comprising an upper processing head and a lower processing head, wherein the upper and lower processing heads respectively face each other with a corresponding surface and form a gap, and each of the corresponding surfaces is provided with a plurality of nozzles; a liquid suction unit comprising an external return pipe and an internal return pipe formed on the upper process head for pumping liquid, an external return pipe and an internal return pipe formed on the lower process head for pumping liquid, and a tank that communicates with the external return line and the internal return line and collects liquid; a transport unit for applying a stage to move the wafer to approach or away from the process head and to maintain the wafer surface Relative to the corresponding surfaces; a liquid supply unit is connected to a part of the nozzles of the upper processing heads by a first input line, and is connected to a part of the nozzles of the lower processing heads by a second input line a third input line is connected to a part of the nozzles of the upper processing heads, and a fourth input line is connected with a part of the nozzles of the lower processing heads; a liquid draining unit is respectively a first switching valve, a second switching valve, a third switching valve and a fourth switching valve are disposed on the first input pipeline, the second input pipeline, the third input pipeline, and the fourth input pipeline. The first switching valve, the second switching valve, the third switching valve and the fourth switching valve are respectively connected by a first drainage line, a second drainage line, a third drainage line and a fourth drainage line The tank is connected to a recovery tank; and an electronic control unit switches the liquid flow direction of the first switching valve, the second switching valve, the third switching valve and the fourth switching valve according to different input signals. The wafer cleaning system of claim 1, wherein the first drainage tube A flow control valve is disposed on each of the drainage tube, the second drainage conduit, the third drainage conduit, and the fourth drainage conduit to control the flow of liquid into the tank or the recovery tank. The wafer cleaning system of claim 1, wherein a first liquid suction valve is disposed between the first switching valve and the upper processing head, and a second liquid separation valve is disposed between the second switching valve and the upper processing head. a third liquid suction valve is disposed between the second liquid suction valve, the third switching valve and the lower processing head, and a fourth liquid suction valve is disposed between the fourth switching valve and the lower processing head, the first to the The fourth liquid suction valve is respectively connected to a drainage system. The wafer cleaning system of claim 3, further comprising a distance sensing unit for detecting the position of the carrier and triggering the corresponding signal accordingly. The wafer cleaning system of claim 4, wherein the distance sensing unit detects that the carrier is in a first position, triggering a first signal, and the electronic control unit switches the first signal according to the first signal. Steering of the switching valve, the second switching valve, the third switching valve and the fourth switching valve, respectively, the liquid in the first to fourth input lines is respectively passed through the first drainage line and the second drainage The pipeline, the third drainage pipeline and the fourth drainage pipeline flow to the tank tank or the recovery tank tank, and simultaneously actuate the first to the fourth liquid suction valve to respectively respectively respectively liquid in the pipeline of the belonging section Retract the drainage system. The wafer cleaning system of claim 4, wherein the distance sensing unit detects a second signal when the carrier is in a second position, and the electronic control unit switches the second signal according to the second signal. Steering of the switching valve, the second switching valve, the third switching valve and the fourth switching valve to cause liquid in the first to fourth input lines to flow to the processing head while stopping the first to the first The suction action of the four suction valves. The wafer cleaning system of claim 5 or 6, wherein the corresponding surface of the upper and lower processing heads is in the order of the wafer entering the gap, and is sequentially a cleaning area, a washing area, and a drying area. The nozzles connecting the first input line and the nozzle connected to the fourth input line are located in the cleaning area, and the nozzles connecting the second input line and the nozzle connected to the third input line are located in the washing area a virtual dividing line is defined in the flushing zone adjacent to the flushing zone and the blown zone, and the carrier is aligned with the virtual dividing line when the terminal end is aligned with the virtual dividing line. When the stage is located at the first position and the front end of the stage is aligned with the virtual dividing line, the carrying stage is located at the second position. The wafer cleaning system of claim 1, wherein the liquid supply unit supplies the liquid to the first input line and the third input line as a chemical liquid, supplies the second input line, and The liquid in the four input lines is deionized water. A wafer cleaning method, which is suitable for a wafer cleaning system according to claim 7, wherein the wafer cleaning method comprises the following steps: the carrier using the transport unit carries the wafer to a first direction travels into the gap, and when the carrier is in the first position, triggering the distance sensing unit to generate the first signal; the electronic control unit switches the first switching valve according to the first signal, The second switching valve, the third switching valve and the fourth switching valve are steered to drain the liquid in the liquid supply unit to the tank or the recovery tank; the electronic control unit activates the first signal according to the first signal a fourth liquid suction valve to respectively suck the liquid in the pipeline of the section to which it belongs to the drainage system; when the loading platform travels in a second direction opposite to the first direction And entering the gap, and when the carrying platform is located in the second position, triggering the distance sensing unit to generate the second signal; the electronic control unit switches the first switching valve, the second switching valve according to the second signal, The third switching valve and the fourth switching valve are steered to flow the liquid in the first to fourth input lines to the processing head; and the electronic control unit stops the first to the fourth suction according to the second signal The suction action of the liquid valve. The wafer cleaning method of claim 9, wherein when the distance sensing unit generates the first signal, interrupting the cleaning operation of the processing head of the wafer cleaning system to make the cleaning area and the processing area Stopping the ejecting liquid, closing the water curtain of the gap, and when the distance sensing unit generates the second signal, starting the cleaning operation of the processing head of the wafer cleaning system, causing the cleaning area and the processing area to eject liquid To create a water curtain effect in the gap. The wafer cleaning method according to claim 9, wherein the liquid supply unit supplies the liquid to the first input line and the third input line as a chemical liquid, supplies the second input line, and The liquid in the four input lines is deionized water.