JP2002124504A - Substrate cleaner and substrate cleaning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate cleaner and a substrate cleaning method which can remove fine foreign substances on a substrate surface enough to improve the cleaning power on the substrate surface. SOLUTION: A spin chuck 12 spins a wafer W with center at its rotary axis R, nozzles 21a, 21b supply hydrofluoroether as a cleaning liquid over the spinning wafer, and ultrasonic heads 22a, 22b apply ultrasonic vibrations to the cleaning liquid, thereby cleaning the wafer W surface with the ultrasonic wave-activated hydrofluoroether.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to various substrates such as a semiconductor wafer, a glass substrate for a liquid crystal display, a PDP (plasma display panel) substrate, a glass substrate for a magnetic disk, and a ceramic substrate. The present invention relates to a substrate cleaning apparatus and a substrate cleaning method for performing a cleaning process.

[0002]

2. Description of the Related Art A semiconductor device manufacturing process includes a process of forming a fine pattern by repeatedly performing processes such as film formation and etching on the surface of a semiconductor wafer (hereinafter, simply referred to as "wafer"). . For fine processing, it is necessary to keep both surfaces of the wafer, particularly one surface (thin film forming surface) of the wafer on which a thin film is formed, clean. Therefore, the wafer is subjected to a cleaning process as necessary. For example, after a thin film formed on a thin film forming surface of a wafer is polished using a polishing agent (hereinafter referred to as a CMP process), the slurry (slurry) remains on both surfaces of the wafer. Need to be removed.

A conventional wafer cleaning apparatus for cleaning a wafer as described above includes, for example, a double-side cleaning apparatus for scrub-cleaning both sides of a wafer while supplying a cleaning liquid to both sides while rotating the wafer, and a wafer cleaning apparatus for rotating the wafer. While supplying the cleaning liquid to both sides, one side of the wafer (thin film forming side)
A surface cleaning device for scrubbing the wafer, and supplying pure water to both surfaces of the wafer while rotating the wafer to wash the water, then stopping the supply of the pure water and rotating the wafer at a high speed to shake off the water on the wafer surface and dry the wafer. It consists of washing and drying equipment.

[0004] In particular, in the above-described surface cleaning apparatus, a cleaning liquid such as a chemical solution or pure water is supplied to the wafer surface in order to remove fine foreign substances such as dust and slurry that could not be removed by the double-side cleaning apparatus. The surface of the wafer is precisely scrub-cleaned with a small-diameter brush or the like.

[0005]

However, with the recent increase in the definition of thin film formation patterns, it has become necessary to remove finer foreign matter. The fine foreign matter is also present in fine concave portions such as a step portion (recess portion) of a pattern formed on the wafer surface and a scratch portion (scratch portion) formed on the wafer surface during the CMP process. The above-described conventional wafer cleaning apparatus has a problem that it cannot cope with the removal of fine foreign matter existing in such fine concave portions. That is, in the conventional wafer cleaning apparatus, the tip of the brush cannot penetrate into the fine concave portion, and even the cleaning liquid cannot penetrate into the fine concave portion due to its surface tension. There is a problem that cannot be removed.

Therefore, fine foreign matters such as dust and slurry remain in the fine concave portions on the wafer surface, leading to a decrease in yield in the semiconductor device manufacturing process, which has been a serious problem.

Accordingly, an object of the present invention is to solve the above technical problems, to sufficiently remove fine foreign substances on the substrate surface, and to improve the cleaning power of the substrate surface and a substrate cleaning apparatus. It is to provide a method.

[0008]

According to a first aspect of the present invention, there is provided a substrate cleaning apparatus for cleaning a substrate by supplying a cleaning liquid to a rotating substrate.
A substrate rotating means for rotating the substrate while holding the substrate, a cleaning liquid supply means for supplying a cleaning liquid containing hydrofluoroether to the substrate being rotated by the substrate rotating means, and a hydrodynamic liquid supplied to the substrate by the cleaning liquid supply means. An ultrasonic wave applying means for applying ultrasonic vibration to a cleaning liquid containing fluoroether.

According to the substrate cleaning apparatus of the present invention, the cleaning liquid supplied to the substrate rotated by the substrate rotating means is hydrofluoroether (hereinafter HF).
E) and ultrasonic vibration. For this reason, the cleaning liquid containing HFE, whose surface tension and viscosity are significantly lower than those of the conventional cleaning liquid, easily penetrates into fine recesses such as recesses and scratches on the substrate surface and has ultrasonic vibration energy. Because
By these cooperative actions, the foreign matter in the fine concave portions on the substrate surface can be satisfactorily removed. Furthermore, the cleaning liquid containing HFE having ultrasonic vibration energy penetrates into the gap between the substrate surface and the foreign matter simply adhering to the substrate surface regardless of the inside of the fine concave portion. Foreign matter can be more favorably removed. In addition, the cleaning liquid on the substrate surface is quickly discharged out of the substrate due to the centrifugal force caused by the rotation of the substrate, so that foreign substances on the substrate surface can be removed in cooperation with the cleaning liquid containing HFE to which ultrasonic vibration has been applied. In addition, it can be better removed.

Further, since the evaporation rate of the cleaning liquid containing HFE is high, there is an advantage that the substrate can be dried quickly after the cleaning. Furthermore, since HFE is non-toxic and has an ozone depletion potential of 0, it has the advantage of being environmentally friendly and reducing the processing cost for its collection and disposal.

It is sufficient that ultrasonic vibration is applied to at least the cleaning liquid supplied to the substrate surface. Ultrasonic vibration may be applied to the cleaning liquid before the cleaning liquid is supplied to the substrate. Ultrasonic vibration may be applied to the cleaning liquid substantially simultaneously with or immediately after the supply of the cleaning liquid to the substrate.

According to a second aspect of the present invention, in the substrate cleaning apparatus of the first aspect, the cleaning liquid supply means supplies the cleaning liquid to both surfaces of the substrate.

According to the substrate cleaning apparatus of the second aspect of the present invention, both surfaces of the substrate can be cleaned using the cleaning liquid containing the HFE to which the ultrasonic vibration is applied. For this reason, ultrasonic vibration is applied to the substrate so as to be sandwiched from both sides of the substrate, and the synergistic effect can further enhance the cleaning effect of the substrate.

According to a third aspect of the present invention, there is provided the substrate cleaning apparatus according to the first or second aspect, further comprising a cleaning brush for scrubbing a surface of the substrate to which the cleaning liquid is supplied. It is a cleaning device.

According to the substrate cleaning apparatus of the third aspect of the present invention, the surface of the substrate can be further scrubbed with the cleaning brush. For this reason, by the cooperative action with the cleaning liquid containing HFE to which the ultrasonic vibration is applied, the foreign matter removed from the fine recesses on the substrate surface can be reliably swept out of the substrate, and the strong Since the foreign substances adhering to the substrate can be removed and removed, the effect of cleaning the substrate can be further enhanced.

According to a fourth aspect of the present invention, in the substrate cleaning apparatus according to any one of the first to third aspects, the substrate is a substrate that has been subjected to a CMP process. Device.

According to the substrate cleaning apparatus of the present invention, the substrate after the CMP process is cleaned. Therefore, C
It is possible to satisfactorily remove foreign matter in the scratch portion, which is particularly large in the substrate after the MP processing.

According to a fifth aspect of the present invention, there is provided a method of cleaning a substrate by supplying a cleaning liquid to a rotating substrate, wherein the cleaning liquid is supplied to the rotating substrate by supplying a cleaning liquid containing hydrofluoroether. A substrate cleaning method comprising: applying a ultrasonic vibration to a cleaning liquid containing the hydrofluoroether supplied to the substrate in the cleaning liquid supply step.

According to the substrate cleaning method of the fifth aspect of the present invention, a substrate processing method having the same effects as the first aspect of the present invention can be provided.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a substrate cleaning apparatus according to an embodiment of the present invention for solving the above technical problems will be described.
This will be described in detail with reference to the accompanying drawings. FIG. 1 is a perspective view schematically showing a configuration of a main part of a substrate cleaning apparatus according to an embodiment of the present invention. In this substrate cleaning apparatus, in another double-sided cleaning apparatus, after scrubbing both surfaces of the wafer W after the CMP processing to remove relatively large foreign matter, the upper surface Wa (thin film forming surface) of the wafer W is mainly removed. Is a device for cleaning again and removing relatively fine foreign matter. In addition, unloading or loading of the wafer W with respect to the substrate cleaning apparatus is performed as follows.
The operation is appropriately performed by a wafer transfer robot or the like having a hand for holding by suction (not shown).

This substrate cleaning apparatus includes a wafer rotating mechanism 10 for rotating around a rotation axis R passing through the center of the wafer W and perpendicular to the wafer W while holding the wafer W, and a wafer upper surface Wa.
And an ultrasonic cleaning mechanism 20 for ultrasonically cleaning the lower surface Wb, and a brush cleaning mechanism 30 for scrub cleaning the upper surface Wa of the wafer.

The wafer rotating mechanism 10 rotates a spin shaft 11 which is rotated by transmitting a rotational driving force from a rotational driving source (not shown).
And a plurality of holding pins 12a provided on the upper end of the spin shaft 11 and provided on the upper surface to move the wafer W to the lower surface Wb.
And a spin chuck 12 held from the side.
With these configurations, the wafer rotating mechanism 10
, The wafer W can be rotated about a rotation axis R of the wafer perpendicular to the wafer W.

Also, The ultrasonic cleaning mechanism 20 includes a hydrofluoroether (hereinafter, referred to as HFE) as a cleaning liquid.
21a, 21b for supplying the wafer W to both sides Wa, Wb of the wafer W, and an ultrasonic head portion 22a having therein a vibration plate for applying ultrasonic vibration to the cleaning liquid supplied from the nozzles 21a, 21b. , 22b
Swing arms 23a and 23b holding the ultrasonic heads 22a and 22b at one end;
and a swing drive source 25 such as a motor for rotating (swing) the motors a and 23b around the arm shafts 24a and 24b within a predetermined angle range. Although not shown, the spin chuck 12 has an opening or notch through which a cleaning liquid supplied from the lower nozzle 21a to the lower surface Wb of the wafer W passes.

With these configurations, the swing drive source 25
Nozzles 21a, 21b and ultrasonic head parts 22a, 2
2b can be reciprocated along the wafer Wa surfaces Wa and Wb. In addition, this nozzle 2
The range in which the cleaning heads 1a and 21b and the ultrasonic head portions 22a and 22b reciprocate is, for example, a range from a position where the cleaning liquid is supplied substantially to the center of the wafer W to a position where the cleaning liquid is supplied slightly outside the outer periphery of the wafer W. is there. Thus, the entire surface of the wafer W and the end surface of the wafer W can be thoroughly cleaned.

The brush cleaning mechanism 30 has a brush part 31 having a sponge brush 31a made of PVA (polyvinyl alcohol) for scrub cleaning the wafer upper surface Wa, and holds the brush part 31 rotatably at one end. The swing arm 32, a swing drive source 34 such as a motor for rotating (swinging) the swing arm 32 around an arm axis 33 within a predetermined angle range, and moving the brush unit 31 and the swing arm 32 up and down. And a lifting drive source 35 such as a cylinder for raising and lowering in the direction. The brush section 31 is rotated by a rotary drive source such as a motor (not shown) provided in the swing arm 32.

With these configurations, the brush cleaning mechanism 30
The brush unit 31 can be moved horizontally along the upper surface Wa of the wafer by the swing drive source 24, and can be moved up and down by the elevation drive source 25. The range in which the brush portion 31 reciprocates is, for example, a range from a position substantially at the center of the wafer W to a position slightly outside the outer periphery of the wafer W. Thus, as in the case of the ultrasonic cleaning mechanism 20, the entire surface of the wafer W and the end surface of the wafer W can be cleaned thoroughly.

Next, a brief description will be given of a cleaning operation performed by the substrate cleaning apparatus having the above configuration. First, in a state where the nozzles 21a and 21b of the ultrasonic cleaning mechanism 20 and the brush part 31 of the brush cleaning mechanism 30 are retracted from above the spin chuck 12, a wafer W whose both surfaces have been cleaned in advance by a wafer transfer robot (not shown). Is carried into the substrate cleaning apparatus, is placed on the spin chuck 12, and is held by the plurality of holding pins 12a. Next, the wafer W
Is rotated at a high speed by a rotation drive source (not shown), and the wafer W is rotated about the rotation axis R.

The oscillating arms 23a and 23b are rotated by the oscillating drive source 25, and the nozzles 21a and 21b of the ultrasonic cleaning mechanism 20 are moved to a position near the upper portion of the center of the wafer. , 21b are supplied with HFE as a cleaning liquid (cleaning liquid supply step).

At this time, the cleaning liquid is applied to the ultrasonic head 22a,
When passing through 22b, the above-described diaphragm applies ultrasonic vibration to the cleaning liquid (ultrasonic application step), and the cleaning liquid to which the ultrasonic vibration has been applied is discharged from the nozzles 21a and 21b.

Thereafter, the nozzle 21 is moved within the above-described range.
The operation of a and 21b reciprocating (oscillating) is repeated a plurality of times to perform ultrasonic cleaning. The scrub cleaning by the brush cleaning mechanism 20 is performed simultaneously with or before or after the cleaning liquid supply step.

Then, the rotation of the wafer W by the wafer rotating mechanism 10 is stopped, and the supply of the cleaning liquid from the nozzles 21a and 21b of the ultrasonic cleaning mechanism 20 is stopped. Finally, the wafer W is unloaded from the substrate cleaning apparatus by a wafer transfer robot (not shown), and the cleaning processing for one wafer W in the substrate processing apparatus is completed. Thereafter, the wafer W is washed and dried by the next washing / drying device to be finally finished, and a plurality of wafers W are stored in a cassette capable of storing a plurality of wafers.

According to the substrate cleaning apparatus and the substrate cleaning method of this embodiment as described above, the cleaning liquid supplied to the wafer W rotated by the spin chuck 12 is HF.
E and ultrasonic vibration are further applied. For this reason, HFE, whose surface tension and viscosity are significantly lower than those of the conventional cleaning liquid, easily penetrates into fine recesses such as recesses and scratches on the surface of the wafer W and has ultrasonic vibration energy. Therefore, the foreign substances in the fine concave portions on the surface of the wafer W can be satisfactorily removed by these cooperative actions. Furthermore, since the HFE to which ultrasonic vibration is applied simply enters the gap between the foreign matter adhering to the surface of the wafer W and the surface of the wafer W, the foreign matter adhering to the surface of the wafer W is further reduced. It can be removed well. In addition, since the evaporation rate of the HFE itself is high,
There is an advantage that the substrate can be dried quickly after cleaning. Furthermore, since HFE is non-toxic and has an ozone depletion potential of 0, it has the advantage of being environmentally friendly and reducing the processing cost for its collection and disposal.

Further, according to the substrate cleaning apparatus of this embodiment, the wafer W is formed by using HFE to which ultrasonic vibration is applied.
To clean both sides Wa and Wb of the wafer W,
Ultrasonic vibration is applied to the wafer W so as to sandwich the wafer W from a and Wb.

Further, according to the substrate cleaning apparatus of this embodiment, since the surface of the wafer W can be scrub-cleaned by the brush part 31, the HF to which ultrasonic vibration is applied can be used.
By cooperating with E, it is possible to reliably sweep out the foreign matter removed from the fine concave portion on the surface of the wafer W, and also to peel off and remove the foreign matter strongly attached to the surface of the wafer W. The effect of cleaning the wafer W can be further enhanced.

Further, according to the substrate cleaning apparatus of this embodiment, since the wafer W after the CMP processing is cleaned,
Foreign matter in the scratch portion, which is particularly large in the wafer W after the MP processing, can be favorably removed.

While the embodiment of the present invention has been described above, the present invention can be embodied in other forms. For example, in the above-described embodiment, HFE is used as the cleaning liquid. However, any cleaning liquid containing HFE may be used. For example, hydrofluoric acid, sulfuric acid, hydrochloric acid,
A mixed solution obtained by mixing a chemical such as nitric acid, phosphoric acid, acetic acid, ammonia, or hydrogen peroxide in HFE may be used. Alternatively, a mixed solution of HFE with an organic solvent such as IPA (isopropyl alcohol), MIBK (methyl isobutyl ketone), acetone, and ethanol, or pure water may be used.

Further, at least one of the above-mentioned chemical solution, organic solvent, and pure water may be supplied to the wafer W before or after the wafer W is cleaned using the cleaning liquid containing HFE. Good. For example, a cleaning solution containing hydrofluoric acid, pure water, and HFE is applied to the wafer W.
The wafer W may be cleaned by supplying in this order, or the cleaning solution containing hydrofluoric acid, HFE, and IPA may be supplied in this order to clean the wafer W.

Here, HFE (hydrofluoroether)
Le) means that some of the hydrogen atoms in ethers are replaced by fluorine atoms.
Is a fluorinated ether containing no chlorine atom,
For example, if the structural formula is CF₃CF₂CF₂CF₂OCH₃
And CF₃CF₂CF ₂CF₂OCH₂CH₃of
There are things.

In the above-described embodiment, the ultrasonic heads 22a and 22b of the ultrasonic cleaning mechanism 20 apply ultrasonic vibration to the cleaning liquid before being supplied to the wafer W. Ultrasonic vibration may be applied to the cleaning liquid supplied to the W surface. Ultrasonic vibration may be applied to the cleaning liquid almost simultaneously with or immediately after the cleaning liquid is supplied to the wafer W. Good. For example, a vibrating plate or a vibrating rod may be arranged close to and parallel to the surface of the wafer W, and ultrasonic vibration may be directly applied to the cleaning liquid supplied to the surface of the wafer W to form a liquid film. In other words, ultrasonic vibration may be applied to the cleaning liquid filled between the vibration plate or the vibration bar and the surface of the wafer W.

In the above-described embodiment, the nozzles 21a and 21b of the ultrasonic cleaning mechanism 20 are oscillated by the oscillating drive source 25 during the cleaning process of the wafer W. It is not necessary to move, for example, the nozzles 21a and 21b of the ultrasonic cleaning mechanism 20
It may be fixed at a position facing the center of the wafer W. In the above-described embodiment, the nozzle 21 a of the ultrasonic cleaning mechanism 20 is
21b is rotated (oscillated) within a predetermined angle range around the arm shafts 24a and 24b, but may be linearly moved along the wafer upper surface Wa.
For example, using a ball screw mechanism or the like, the wafer upper surface Wa
Nozzles 21a and 21b of the ultrasonic cleaning mechanism 20 in a direction away from and approaching the rotation axis R of the wafer along
May be reciprocated linearly (oscillated).

In the above-described embodiment, the nozzles 21a and 21b of the ultrasonic cleaning mechanism 20 are provided corresponding to both surfaces Wa and Wb of the wafer W, respectively.
Only one nozzle corresponding to any one surface of the wafer W may be provided.

In the above-described embodiment, the brush part 31 of the brush cleaning mechanism 30 for scrub cleaning the upper surface Wa of the wafer is a sponge brush 3 made of PVA.
1a, but may be made of any material such as a sponge brush made of polyurethane, polyethylene, or polypropylene. Or
The fiber brush is not limited to the sponge brush, and may be a fibrous brush in which a large number of fibers made of nylon or the like are planted.

In the above-described embodiment, the brush cleaning mechanism 3 for scrub cleaning the wafer upper surface Wa is used.
Although 0 is provided, it does not have to be provided.

In the above-described embodiment, the wafer rotating mechanism 10 includes a plurality of holding pins 1 provided on the upper surface.
Although the spin chuck 12 holding the wafer W from the lower surface Wb side by 2a is used to rotate the wafer W while holding the same, the spin chuck rotates the wafer W while sucking and holding the lower surface Wb of the wafer W. Is also good.

Alternatively, the wafer rotation mechanism 10 may be at least three roller pins that rotate around an axis parallel to the rotation axis R of the wafer while abutting the end face of the peripheral portion of the wafer W. The wafer rotating mechanism 10 using the roller pins is particularly effective when both surfaces of the wafer W are subjected to ultrasonic cleaning, and both surfaces (Wa and Wb) of the wafer W are used.
Ultrasonic cleaning can be performed on the entire area of the substrate.

In one embodiment described above, C
Although the case of cleaning the wafer W after the MP processing has been described, the present invention is not limited to this, and the present invention can be widely applied to a case of cleaning the wafer W.

Further, in the above-described embodiment,
Although the case where the semiconductor wafer W is cleaned has been described, the present invention relates to a glass substrate for a liquid crystal display device, a PDP (plasma display panel) substrate, or a glass substrate or a ceramic substrate for a magnetic disk. It can be widely applied to cleaning of various other substrates. Further, as for the shape of the substrate, the present invention can be applied not only to the circular substrate of the above-described embodiment but also to a square or rectangular square substrate.

In addition, various design changes can be made within the scope of the matters described in the claims.

[0049]

As described above in detail, according to the substrate cleaning apparatus of the first aspect of the present invention, the cleaning liquid containing HFE easily penetrates into the fine recesses such as the recesses and scratches on the substrate surface. Together with the ultrasonic vibration energy, it is possible to remove foreign matter in the fine recesses on the substrate surface by the cooperative action, and furthermore, to remove the foreign matter adhering to the substrate surface and the substrate surface. Since the cleaning liquid containing HFE to which ultrasonic vibration is applied enters the gap between the substrate and the substrate, the foreign matter attached to the substrate surface can be more effectively removed. Further, the centrifugal force associated with the rotation of the substrate and H having ultrasonic vibration energy
By cooperating with the cleaning liquid containing FE, foreign substances on the surface of the substrate can be more favorably removed.

According to the apparatus for cleaning a substrate according to the second aspect of the present invention, an ultrasonic vibration is applied to the substrate so as to be sandwiched from both sides of the substrate, and the effect of cleaning the substrate can be further enhanced due to the synergistic effect.

According to the substrate cleaning apparatus of the third aspect of the present invention, the foreign matter removed from the fine recesses on the substrate surface can be reliably removed from the substrate by the cooperative action with the cleaning liquid containing HFE to which the ultrasonic vibration is applied. In addition, foreign substances strongly adhering to the substrate surface can be removed and removed, so that the effect of cleaning the substrate can be further enhanced.

According to the substrate cleaning apparatus of the fourth aspect of the present invention, there is an effect that foreign matter in the scratch portion, which is particularly large in the substrate after the CMP processing, can be favorably removed.

According to the substrate cleaning method of the fifth aspect, there is an effect that a substrate processing method having the same effect as the first aspect of the invention can be provided.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing a configuration of a main part of a substrate cleaning apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 Wafer rotating mechanism (substrate rotating means) 11 Spin shaft 12 Spin chuck 12a Holding pin 20 Ultrasonic cleaning mechanism 21a, 21b Nozzle (cleaning liquid supply means) 22a, 22b Ultrasonic head section (ultrasonic applying means) 23a, 23b Swing Arms 24a, 24b Arm shaft 25 Swing drive source 30 Brush cleaning mechanism 31 Brush part 31a Sponge brush (wash brush) 32 Swing arm 33 Arm shaft 34 Swing drive source 35 Elevating drive source K Gap space R Wafer rotation axis W Wafer (substrate) Wa Wafer upper surface Wb Wafer lower surface

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B08B 3/02 B08B 3/02 C 3/08 3/08 Z 3/12 3/12 D C11D 7/28 C11D 7 / 28

Claims (5)

[Claims] 1. A substrate cleaning apparatus for cleaning a substrate by supplying a cleaning liquid to the rotating substrate, comprising: a substrate rotating means for rotating the substrate while holding the substrate; A cleaning liquid supply means for supplying a cleaning liquid containing: a cleaning liquid supply means for supplying ultrasonic vibration to the cleaning liquid containing hydrofluoroether supplied to the substrate by the cleaning liquid supply means. apparatus. 2. The substrate cleaning apparatus according to claim 1, wherein the cleaning liquid supply unit supplies the cleaning liquid to both surfaces of the substrate. 3. The substrate cleaning apparatus according to claim 1, further comprising a cleaning brush for scrub cleaning a surface of the substrate to which the cleaning liquid is supplied. 4. The substrate cleaning apparatus according to claim 1, wherein the substrate is a substrate that has been subjected to a CMP process. 5. A substrate cleaning method for supplying a cleaning liquid to a rotating substrate to clean the substrate, comprising: a cleaning liquid supply step of supplying a cleaning liquid containing hydrofluoroether to the rotating substrate; An ultrasonic wave applying step of applying an ultrasonic vibration to the cleaning liquid containing the hydrofluoroether supplied to the substrate.