Substrate cleaning method and substrate cleaning apparatus

Abstract

This invention provides a substrate cleaning method and apparatus with higher cleaning capabilities. The substrate cleaning method includes: a first step of supplying a chemical solution to the lower surface of the substrate; and a second step of subsequently supplying a liquid containing air bubbles to the lower surface of the substrate.

Description

Technical Field

[0001] This invention relates to a substrate cleaning method and a substrate cleaning apparatus. Prior Technology

[0002] Patent document 1 discloses a substrate cleaning method in which an etching liquid is supplied to the upper and lower surfaces of the substrate for chemical cleaning, and then pure water is supplied to remove the etching liquid. [Existing Technical Documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2000-176386 Summary of the Invention

[0004] [The problem the invention aims to solve]

[0005] The present invention aims to provide a substrate cleaning method and a substrate cleaning apparatus with higher cleaning capabilities. [Technical means to solve the problem]

[0006] According to one aspect of the present invention, a substrate cleaning method is provided, comprising: a first step of supplying a chemical solution to the lower surface of the substrate; and a second step of subsequently supplying a liquid containing air bubbles to the lower surface of the substrate.

[0007] Ideally, the first step forms a liquid film of the drug solution on the lower surface of the substrate, and the second step replaces the liquid film with the bubble-containing liquid.

[0008] Ideally, the step of generating the bubble-containing liquid should be included before the second step.

[0009] Ideally, in the step of generating the bubble-containing liquid, bubbles are generated in the cleaning fluid by ultrasonic waves to generate the bubble-containing liquid.

[0010] Ideally, the supply flow rate of the bubble-containing liquid in the second step is faster than the supply flow rate of the drug solution in the first step.

[0011] Ideally, in the first step, the liquid medicine is supplied from a first nozzle, and in the second step, the bubble-containing liquid is supplied from a second nozzle, which is different from the first nozzle.

[0012] Ideally, in the second step, the bubble-containing liquid is supplied from a single-tube nozzle.

[0013] Ideally, in the second step, the bubble-containing liquid is supplied to the vicinity of the center of the lower surface of the substrate and to the periphery of the substrate.

[0014] Ideally, in the second step, the bubble-containing liquid and the ultrasonic cleaning solution are supplied to the lower surface of the substrate.

[0015] Ideally, in the second step, the bubble-containing liquid and the two fluids are supplied to the lower surface of the substrate.

[0016] Ideally, the bubble-containing liquid is pure water containing bubbles.

[0017] Ideally, the diameter of the bubbles in the bubble-containing liquid is greater than 1 μm and less than 500 μm.

[0018] Ideally, the bubbles in the bubble-containing liquid are one or more of nitrogen, hydrogen, ozone, carbon dioxide, and oxygen.

[0019] Ideally, a metal film is formed on the upper surface of the substrate, and the bubbles contained in the bubble-containing liquid include nitrogen and hydrogen bubbles, or nitrogen and hydrogen bubbles.

[0020] Ideally, before the first step, a step of scrubbing the lower surface of the substrate is included. Ideally, in the first step, a liquid containing bubbles is supplied.

[0021] According to another aspect of the present invention, a substrate cleaning apparatus is provided, comprising: a substrate holding section for holding a substrate; a first nozzle for supplying a chemical solution to the lower surface of the held substrate; a second nozzle for supplying a bubble-containing liquid to the lower surface of the held substrate; and a control section for controlling the supply of the bubble-containing liquid to the second nozzle after the first nozzle supplies the chemical solution.

[0022] Ideally, the second nozzle includes: a gas supply section; a liquid supply section; a bubble-containing liquid generating section for mixing gas from the gas supply section with liquid from the liquid supply section to generate the bubble-containing liquid; a housing having the bubble-containing pure water generating section disposed therein; and a single-tube nozzle for spraying the generated bubble-containing liquid onto the lower surface of the substrate.

[0023] Ideally, the second nozzle includes: a gas supply section; a liquid supply section; a bubble-containing liquid generating section for mixing gas from the gas supply section with liquid from the liquid supply section to generate the bubble-containing liquid; and a housing having a spray hole for spraying the generated bubble-containing liquid.

[0024] Ideally, the upper surface of the housing has an inclined surface extending obliquely downward from the injection hole. [The effects of the invention]

[0025] Improved cleaning capabilities. Simple Explanation of the Diagram

[0026] Figure 1A is a diagram illustrating an example of a conventional substrate cleaning method. Figure 1B is a diagram illustrating an example of a conventional substrate cleaning method. Figure 2A is a schematic diagram illustrating a substrate cleaning method according to an embodiment of the present invention. Figure 2B is a schematic diagram illustrating a substrate cleaning method according to an embodiment of the present invention. Figure 2C is a schematic diagram illustrating a substrate cleaning method according to an embodiment of the present invention. Figure 3 is a schematic perspective view of a substrate cleaning apparatus according to one embodiment. Figure 4 is a schematic diagram showing an example of a pure water supply nozzle 5. Figure 5A is a schematic diagram showing another example of a pure water supply nozzle 5. Figure 5B is a schematic diagram showing another example of a pure water supply nozzle 5. Figure 6A is a schematic perspective view of a substrate cleaning apparatus according to another embodiment. Figure 6B is a schematic perspective view of a substrate cleaning apparatus according to another embodiment. Figure 7 is a flowchart showing the sequence of substrate cleaning. Implementation

[0027] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. This invention mainly relates to the cleaning of the lower surface of a substrate. First, the outline of this invention will be described.

[0028] Figures 1A and 1B illustrate an example of a conventional substrate cleaning method. First, the upper surface of substrate W is wiped using a sponge roller 21, and the lower surface of substrate W is wiped using a sponge roller 22 (Figure 1A). The upper surface of substrate W refers to the vertically upward-facing surface when held (typically the surface where devices are formed). The lower surface of substrate W refers to the vertically downward-facing surface when held (typically the surface where no devices are formed).

[0029] When wiping is complete, sponge rollers 21 and 22 are removed from the substrate W. Then, chemical rinse is performed on the lower surface of the substrate W through the chemical supply nozzle 4 (Fig. 1B). As shown, a liquid film 100 of chemical solution is formed on the lower surface of the substrate W by supplying chemical solution. The liquid film 100 contains foreign matter and the like removed from the lower surface of the substrate W.

[0030] Next, pure water is supplied to the lower surface of the substrate W from a pure water supply nozzle (not shown) to rinse the liquid film 100 away.

[0031] Figures 2A-2C are schematic diagrams illustrating a substrate cleaning method according to an embodiment of the present invention. First, the upper and lower surfaces of the substrate W are wiped clean. Next, the lower surface of the substrate W is supplied with a chemical solution for chemical rinsing, which is the same as in the conventional method, and a liquid film 100 of the chemical solution is formed on the lower surface of the substrate W (Figure 2A).

[0032] Next, pure water containing air bubbles (hereinafter referred to as "air-filled pure water") is supplied to the lower surface of the substrate W from the pure water supply nozzle 5. Air bubbles in the air-filled pure water 101 reaching the lower part of the liquid film 100 of the drug solution rise in the air-filled pure water 101 due to the buoyancy of the air bubbles, thereby entering the interface between the lower surface of the substrate W and the liquid film 100 (Fig. 2B). As a result, the liquid film 100 detaches from the lower surface of the substrate W and falls off, thereby efficiently removing the liquid film 100 (Fig. 2C).

[0033] Thus, by supplying pure water containing air bubbles, the liquid film 100 of the medicine is replaced by air bubbles, thereby inhibiting the liquid film 100 from remaining on the lower surface of the substrate W, thus improving the cleaning ability.

[0034] The following is a detailed explanation. Figure 3 is a schematic perspective view of a substrate cleaning apparatus according to one embodiment. The substrate cleaning apparatus includes: four rollers 11-14 (substrate holding parts) arranged on approximately the same horizontal plane; two cylindrical sponge rollers 21 and 22 serving as cleaning parts; a rotation mechanism 31 and a rotation mechanism 32 for rotating the sponge rollers 21 and 22 respectively; a chemical supply nozzle 4; a pure water supply nozzle 5; and a control unit 6.

[0035] Roller 11 has a two-section structure consisting of a holding portion 11a and a shoulder (support portion) 11b. The diameter of the shoulder 11b is larger than the diameter of the holding portion 11a, and the holding portion 11a is provided on the shoulder 11b. Rollers 12 to 14 also have the same structure as roller 11. Rollers 11 to 14 can be moved toward each other and away from each other by a drive mechanism (e.g., an air cylinder) not shown. By bringing rollers 11 to 14 closer together, the holding portions 11a to 14a can keep the substrate W approximately horizontal. Furthermore, at least one of rollers 11 to 14 is a structure driven by a rotation mechanism not shown, thereby enabling the substrate W to rotate in the horizontal plane.

[0036] The sponge roller 21 extends in a horizontal plane and contacts the upper surface of the substrate W held by rollers 11 to 14 to clean the upper surface. The sponge roller 21 rotates about its length direction via a rotating mechanism 31. The rotating mechanism 31 is mounted on a guide rail 33 that guides its vertical movement and is supported by a lifting drive mechanism 34. The lifting drive mechanism 34 moves the rotating mechanism 31 and the sponge roller 21 vertically along the guide rail 33.

[0037] The sponge roller 22 extends in the horizontal plane and contacts the lower surface of the substrate W held by rollers 11 to 14 to wipe the lower surface. The sponge roller 22 is positioned below the sponge roller 21 and is rotated about the length direction of the sponge roller 22 by a rotating mechanism 32. Although the lifting drive mechanism and the like are not shown in the figure, the rotating mechanism 32 and the sponge roller 22 also move in the vertical direction, just like the sponge roller 21.

[0038] The liquid supply nozzle 4 is located below the substrate W (directly below or diagonally below) and supplies liquid to the lower surface of the substrate W.

[0039] The pure water supply nozzle 5 is located below the substrate W (directly below or diagonally below) and supplies pure water to the lower surface of the substrate W. As one of the features of this embodiment, the pure water supply nozzle 5 supplies pure water containing air bubbles.

[0040] The control unit 6 controls the entire substrate cleaning apparatus. As one of the features of this embodiment, the control unit 6 controls the liquid supply nozzle 4 to supply liquid, and then controls the pure water supply nozzle 5 to supply pure water containing air bubbles.

[0041] A specific structural example of the pure water supply nozzle 5 is shown. Figure 4 is a schematic diagram showing an example of a pure water supply nozzle 5. The pure water supply nozzle 5 includes: a pure water supply section 51, a gas supply section 52, a housing 53, a bubble-containing pure water generating section 54, and a single-tube nozzle 55. Pure water is supplied from the pure water supply section 51 to the bubble-containing pure water generating section 54 disposed within the housing 53, and a predetermined gas is supplied from the gas supply section 52 to the bubble-containing pure water generating section 54 disposed within the housing 53. Micropores are formed in the bubble-containing pure water generating section 54 to mix pure water and gas to generate bubble-containing pure water. The generated bubble-containing pure water is sprayed obliquely upward from the single-tube nozzle 55 protruding from the upper surface of the housing 53. The sprayed bubble-containing pure water reaches near the center of the lower surface of the substrate W.

[0042] The pure water supply nozzle 5 can be fixed in a predetermined position, or it can move in a straight line or swing. When swinging, it is ideal for the pure water supply nozzle 5 to swing between a position near the center of the lower surface of the substrate W where the pure water containing air bubbles is sprayed, and a position where it is sprayed to the periphery of the substrate W.

[0043] Furthermore, there are no particular restrictions on the supply angle of the bubble-containing pure water relative to the lower surface of the substrate W. However, when supplying bubble-containing pure water only to the center of the lower surface of the substrate W, it is also considered that the bubble-containing pure water may not reach the periphery of the substrate W. Therefore, it is also possible to provide two or more pure water supply nozzles 5, one of which supplies bubble-containing pure water to the vicinity of the center of the lower surface of the substrate W, and the other of which supplies bubble-containing pure water to the periphery of the lower surface of the substrate W.

[0044] Figures 5A and 5B are schematic diagrams illustrating another example of the pure water supply nozzle 5 (Figure 5A is a side view, and Figure 5B is a schematic cross-sectional view). The pure water supply nozzle 5 includes: a pure water supply section 51, a gas supply section 52, a housing 53, and a bubble-containing pure water generating section 54. Pure water is supplied from the pure water supply section 51 to the bubble-containing pure water generating section 54 disposed within the cylindrical housing 53, and a predetermined gas is supplied from the gas supply section 52 to the bubble-containing pure water generating section 54 disposed within the cylindrical housing 53. Micropores are formed in the bubble-containing pure water generating section 54, where pure water and gas are mixed to generate bubble-containing pure water. The generated bubble-containing pure water is sprayed upwards from one or more spray holes 531 formed on the upper surface of the housing 53. The sprayed bubble-containing pure water reaches the lower surface of the substrate W.

[0045] By providing multiple spray holes 531, it is possible to spray bubble-containing pure water onto a wide area of ​​the substrate W. Ideally, a portion of the spray holes 531 are disposed below the center of the lower surface of the substrate W, and another portion is disposed below the periphery of the lower surface of the substrate W.

[0046] Furthermore, it is ideal to avoid the accumulation of air bubbles on the upper surface of the housing 53. As an example, as shown in the figure, an inclined surface 532 extending obliquely downward from the injection hole 531 is provided. As a result, the air bubbles rise along the inclined surface 532, do not accumulate on the upper surface of the housing 53, and are discharged to the injection hole 531.

[0047] From the perspective of obtaining the buoyancy of the bubbles, the diameter of the bubbles in the bubble-containing pure water is ideally large without breaking. However, the diameter of the bubbles is ideally smaller than the liquid film of the drug solution formed on the lower surface of the substrate W. Specifically, the thickness of the liquid film is ideally about 200 μm to 500 μm, so the diameter of the bubbles is ideally 1 μm or more and 500 μm or less, more preferably 100 μm or more and 500 μm or less. Furthermore, the diameter of the single-tube nozzle 55 in FIG4 or the diameter of the injection hole 531 in FIG5A and FIG5B is ideally larger than the diameter of the bubbles.

[0048] Moreover, the density of bubbles in pure water containing bubbles should ideally be as high as possible, especially when the gas phase fraction is above 80%, the cleaning effect becomes higher.

[0049] The size or density of the bubbles can be adjusted, for example, by the size of the micropores in the bubble-containing pure water generating unit 54 shown in Figures 4 and 5B. Furthermore, the bubble-containing pure water generating unit 54 can generate bubbles in pure water by applying ultrasound, and the size or density of the bubbles can also be adjusted by the frequency of the ultrasound.

[0050] To efficiently remove the liquid film of the medicine by utilizing the buoyancy of the bubbles, it is ideal to have a fast supply flow rate of bubble-containing pure water without causing the bubbles to break. Specifically, it is ideal for the supply flow rate of bubble-containing pure water from the pure water supply nozzle 5 to be faster than the supply flow rate of the medicine from the medicine supply nozzle 4.

[0051] Furthermore, in addition to the liquid supply nozzle 4 and the pure water supply nozzle 5, an ultrasonic nozzle 61 (see Figure 6A) may also be provided to supply ultrasonic cleaning fluid to the lower surface of the substrate W. Alternatively, in addition to the liquid supply nozzle 4 and the pure water supply nozzle 5, a two-fluid jet nozzle 62 (see Figure 6B) may also be provided to supply two fluids to the lower surface of the substrate W. The two fluids refer to, for example, a mixture of liquid (e.g., pure water) and gas (e.g., nitrogen).

[0052] Furthermore, the gas in the bubbles can be one or a mixture of two or more of nitrogen, hydrogen, ozone, carbon dioxide, and oxygen. That is, these gases can be supplied from the gas supply unit 52 in Figure 4 or Figure 5B.

[0053] When the bubbles contain nitrogen, the nitrogen bubbles reduce the dissolved oxygen near the substrate W, and the nitrogen dissolved in pure water acts as functional water, inhibiting oxygen dissolution. This inhibits corrosion (especially oxidation) of the metal film. Similarly, when the bubbles contain hydrogen, corrosion (especially oxidation) of the metal film is inhibited, and the re-adhesion of cerium oxide abrasive particles (the polishing slurry used in substrate polishing) is also inhibited. When the bubbles contain ozone, the substrate W becomes hydrophilic, and organic and inorganic matter adhering to the substrate W is oxidized and dissolved. When the bubbles contain carbon dioxide, the substrate's charge is suppressed. By mixing bubbles of various gases, their respective effects can be obtained.

[0054] The effect varies depending on the type of gas contained in the bubbles; therefore, it is ideal to supply bubble-containing pure water containing bubbles of the type of gas corresponding to the substrate W to be cleaned. For example, when a metal film such as a copper film is formed on the upper surface of the substrate, it is ideal to use nitrogen or hydrogen to suppress the oxidation of the metal film.

[0055] Furthermore, other liquids containing air bubbles can be supplied instead of pure water. The liquid supplied from the liquid supply nozzle can contain air bubbles, thereby further enhancing the cleaning ability.

[0056] Figure 7 is a process diagram showing the sequence of substrate cleaning. Furthermore, before substrate W is cleaned, i.e., when substrate W is being moved in, rollers 11 to 14 are positioned away from each other. Also, sponge roller 21 rises and sponge roller 22 falls.

[0057] Furthermore, with the sponge rollers 21 and 22 removed from the substrate holding position, the substrate W, conveyed by a transfer unit (not shown, for example, after grinding), is placed on the shoulders 11b of roller 11 to 14b of roller 14. Subsequently, by moving rollers 11 and 14 in a direction closer to each other, i.e., toward the substrate W, the substrate W is held approximately horizontally by holding portions 11a and 14a. Thus, the substrate W is held in a roughly horizontal direction by rollers 11 and 14 (step S1).

[0058] In addition, when the substrate W to be cleaned has been polished, polishing debris or polishing fluid may sometimes adhere to the upper and lower surfaces of the substrate W.

[0059] Next, sponge roller 21 descends to contact the upper surface of substrate W, and sponge roller 22 rises to contact the lower surface of substrate W. Furthermore, substrate W is rotated in the horizontal plane by rollers 11 to 14, and sponge rollers 21 and 22 rotate around their respective axes while contacting the upper and lower surfaces of substrate W, thereby cleaning the upper and lower surfaces of substrate W (step S2). When cleaning is complete, sponge roller 21 rises and leaves the upper surface of substrate W, and sponge roller 22 descends and leaves the lower surface of substrate W.

[0060] Subsequently, liquid medicine is supplied to the lower surface of the substrate W through the liquid medicine supply nozzle 4 (step S3). In other words, the control unit 6 controls the way in which the liquid medicine supply nozzle 4 supplies liquid medicine to the lower surface of the substrate W. As a result, a liquid film of liquid medicine is formed on the lower surface of the substrate W, and the lower surface of the substrate W is rinsed with liquid medicine.

[0061] After rinsing with the chemical solution, bubble-containing pure water is supplied to the lower surface of the substrate W through the pure water supply nozzle 5 (step S4). In other words, the control unit 6 controls the supply of bubble-containing pure water to the lower surface of the substrate W through the pure water supply nozzle 5. As a result, during pure water rinsing, as illustrated using Figures 2A to 2C, the liquid film of the chemical solution formed on the lower surface of the substrate W (at least a portion, ideally most, and more ideally all) is replaced by bubble-containing pure water and removed from the lower surface of the substrate W.

[0062] Alternatively, if the substrate cleaning apparatus has an ultrasonic nozzle 61, the ultrasonic cleaning fluid can also be supplied in step S4. Furthermore, if the substrate cleaning apparatus has a two-fluid jet nozzle 62, the two fluids can also be supplied in step S4.

[0063] Thus, in this embodiment, during the cleaning of the lower surface of the substrate W, after rinsing with the cleaning solution, pure water containing air bubbles is supplied. Therefore, the air bubbles cause the liquid film of the cleaning solution to detach from the lower surface of the substrate W, preventing the liquid film from remaining on the lower surface of the substrate W. As a result, the cleaning efficiency is improved.

[0064] Furthermore, the method for generating bubbles is not limited to the methods illustrated in Figure 4 or Figures 5A and 5B, and well-known methods may also be used.

[0065] The embodiments described herein are intended for implementation by those skilled in the art. Various modifications to the embodiments can, of course, be made by those skilled in the art, and the technical concept of the present invention can be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but should be considered within the broadest scope of the technical concept defined by the claims.

[0066] 4: Liquid supply nozzle 5: Pure water supply nozzle 6: Control Department 11~14: Rollers 11a~14a: Retention section 11b~14b: Shoulders 21, 22: Sponge rollers 31, 32: Rotating mechanism 33: Guide rail 34: Lifting drive mechanism 51: Pure Water Supply Department 52: Gas Supply Department 53: Shell 54: Pure water generation section containing air bubbles 55: Single-tube nozzle 61: Ultrasonic nozzle 62: Two-fluid jet nozzle 100: Liquid film 101: Pure water containing bubbles 531: Injection port 532: Inclined surface S1~S4: Steps W: substrate

Claims

1. A substrate cleaning method, comprising: The first step is to supply a liquid medicine to the lower surface of the substrate, thereby forming a liquid film of the liquid medicine on the lower surface of the substrate. The steps include mixing pure water with gas to generate a bubble-containing liquid, and a second step, in which the bubble-containing liquid is then supplied to the lower surface of the substrate to replace the liquid film with the bubble-containing liquid.

2. The substrate cleaning method as claimed in claim 1, wherein the supply flow rate of the bubble-containing liquid in the second step is faster than the supply flow rate of the chemical solution in the first step.

3. The substrate cleaning method as claimed in claim 1 or 2, wherein in the first step, the chemical solution is supplied from a first nozzle, and in the second step, the bubble-containing liquid is supplied from a second nozzle different from the first nozzle.

4. The substrate cleaning method as claimed in claim 1 or 2, wherein in the second step, the bubble-containing liquid is supplied from a single-tube nozzle.

5. The substrate cleaning method as claimed in claim 1 or 2, wherein in the second step, the bubble-containing liquid is supplied to the vicinity of the center of the lower surface of the substrate and to the periphery of the substrate.

6. The substrate cleaning method as claimed in claim 1 or 2, wherein in the second step, the bubble-containing liquid and the ultrasonic cleaning fluid are supplied to the lower surface of the substrate.

7. The substrate cleaning method as claimed in claim 1 or 2, wherein in the second step, the bubble-containing liquid and the two fluids are supplied to the lower surface of the substrate.

8. The substrate cleaning method as claimed in claim 1 or 2, wherein the bubble-containing liquid is pure water containing bubbles.

9. The substrate cleaning method as claimed in claim 1 or 2, wherein the diameter of the bubbles contained in the bubble-containing liquid is 1 μm or more and 500 μm or less.

10. The substrate cleaning method as claimed in claim 1 or 2, wherein the bubbles contained in the bubble-containing liquid are one or more of nitrogen, hydrogen, ozone, carbon dioxide and oxygen.

11. The substrate cleaning method of claim 13, wherein a metal film is formed on the upper surface of the substrate, and the bubbles contained in the bubble-containing liquid include nitrogen and hydrogen bubbles, or nitrogen and hydrogen bubbles.

12. The substrate cleaning method as claimed in claim 1 or 2, wherein prior to the first step, a step of wiping the lower surface of the substrate is included.

13. The substrate cleaning method as claimed in claim 1 or 2, wherein in the first step, a solution containing air bubbles is supplied.

14. A substrate cleaning apparatus, comprising: Substrate holding section, for holding substrate; The first nozzle supplies the liquid medicine to the lower surface of the substrate being held. A second nozzle supplies bubble-containing liquid to the lower surface of the held substrate; and a control unit controls the second nozzle to supply the bubble-containing liquid after the first nozzle supplies the liquid medicine; the second nozzle includes: a gas supply unit; a liquid supply unit; and a bubble-containing liquid generating unit that mixes gas from the gas supply unit with liquid from the liquid supply unit to generate the bubble-containing liquid.

15. The substrate cleaning apparatus of claim 14, wherein the second nozzle comprises: A single nozzle is used to spray the generated bubble-containing liquid onto the lower surface of the substrate.

16. A substrate cleaning apparatus, comprising: Substrate holding section, for holding substrate; The first nozzle supplies the liquid medicine to the lower surface of the substrate being held. A second nozzle supplies bubble-containing liquid to the lower surface of the held substrate; and a control unit controls the second nozzle to supply the bubble-containing liquid after the first nozzle supplies the liquid medicine; the second nozzle includes: a gas supply unit; a liquid supply unit; a bubble-containing liquid generating unit that mixes gas from the gas supply unit with liquid from the liquid supply unit to generate the bubble-containing liquid; a housing having a spray hole for spraying the generated bubble-containing liquid; the upper surface of the housing has an inclined surface extending obliquely downward from the spray hole.

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