CN219393353U - Roller assembly - Google Patents

Abstract

The utility model discloses a roller assembly, which is coupled with a box body for realizing wafer cleaning, wherein the roller assembly comprises a movable wheel, a rotating shaft, a mounting seat and a sealing assembly; the sealing component is respectively fixed with the mounting seat and the box body and is used for sealing a gap between the mounting seat and the box body; the sealing assembly comprises a sealing gasket, an outer pressing ring and an inner pressing ring, the inner pressing ring fixes the sealing gasket with the mounting seat, the outer pressing ring fixes the sealing gasket with the box body, and the inner pressing ring is positioned on the inner side of the outer pressing ring.

Description

Roller assembly

Technical Field

The utility model relates to the technical field of semiconductor wafer cleaning, in particular to a roller assembly.

Background

In the semiconductor field, the cleanliness of the wafer surface is one of the important factors affecting the reliability of semiconductor devices. In wafer processing, for example: deposition, plasma etching, photolithography, electroplating, etc., may introduce contamination and/or particles on the wafer surface, resulting in reduced cleanliness of the wafer surface and low yield of semiconductor devices fabricated. Therefore, the surface cleaning process is required to be performed several times during the wafer manufacturing process to remove the contaminants such as metal ions, atoms, organic matters, and particles attached to the wafer surface.

The scrubbing module for cleaning the wafer is provided with a roller for driving the wafer to rotate or a roller for rotating along with the wafer, the roller is in direct contact with the wafer, the edge of the wafer is found to be difficult to clean in the actual production process, and pollutants still remain on the edge of the wafer after scrubbing treatment, so that the pollutants are difficult to thoroughly remove.

Disclosure of Invention

The embodiment of the utility model provides a roller assembly, which aims at solving at least one of the technical problems existing in the prior art.

The embodiment of the utility model provides a roller assembly, which is coupled with a box body for realizing wafer cleaning, wherein the roller assembly comprises a movable wheel, a rotating shaft, a mounting seat and a sealing assembly; the sealing component is respectively fixed with the mounting seat and the box body and is used for sealing a gap between the mounting seat and the box body; the sealing assembly comprises a sealing gasket, an outer pressing ring and an inner pressing ring, the inner pressing ring fixes the sealing gasket with the mounting seat, the outer pressing ring fixes the sealing gasket with the box body, and the inner pressing ring is positioned on the inner side of the outer pressing ring.

In one embodiment, the upper part of the outer pressure ring is provided with a water blocking structure.

In one embodiment, the water blocking structure comprises a water blocking eave formed by extending outwards from the peripheral edge of the outer pressing ring and a first groove formed between the water blocking eave and the box body.

In one embodiment, the water blocking eaves is a half-moon structure gradually narrowing along the direction from high to low.

In one embodiment, the lower portion of the outer pressure ring has a drainage structure.

In one embodiment, the drainage structure is a notch at the bottom of the outer pressure ring.

In one embodiment, the inner circumferential surface of the outer pressure ring is provided with a first guiding inclined surface.

In one embodiment, the inner pressure ring has a water guiding structure.

In one embodiment, the water guiding structure is a water guiding eave extending obliquely outwards from the outer peripheral edge of the inner pressure ring towards one side of the movable wheel.

In one embodiment, the water guiding eave is annular.

In one embodiment, the outer peripheral edge of the water guiding eave is provided with a second guiding inclined surface.

In one embodiment, the rotating shaft is rotatably arranged in the mounting seat, and one end of the rotating shaft is connected with the movable wheel.

The beneficial effects of the embodiment of the utility model include: the sealing function of the roller assembly is realized, and the pollution discharge capacity is improved.

Drawings

The advantages of the present utility model will become more apparent and more readily appreciated from the detailed description given in conjunction with the following drawings, which are meant to be illustrative only and not limiting of the scope of the utility model, wherein:

FIG. 1 illustrates a wafer cleaning apparatus according to an embodiment of the present utility model;

FIG. 2 illustrates a roller assembly with the loose pulley removed in accordance with one embodiment of the present utility model;

fig. 3 shows a cross section of the roller assembly.

Detailed Description

The following describes the technical scheme of the present utility model in detail with reference to specific embodiments and drawings thereof. The examples described herein are specific embodiments of the present utility model for illustrating the concept of the present utility model; the description is intended to be illustrative and exemplary in nature and should not be construed as limiting the scope of the utility model in its aspects. It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. In addition to the embodiments described herein, those skilled in the art can adopt other obvious solutions based on the disclosure of the claims of the present application and the specification thereof, including those adopting any obvious substitutions and modifications to the embodiments described herein. It should be understood that the following description of the embodiments of the present utility model, unless specifically stated otherwise, is established in the natural state of the relevant devices, apparatuses, components, etc. in which no external control signal or driving force is given, in order to facilitate understanding.

Furthermore, it is noted that terms such as front, back, upper, lower, left, right, top, bottom, front, back, horizontal, vertical, and the like used herein are merely used for ease of description to aid in understanding the relative position or orientation and are not intended to limit the orientation of any apparatus or structure.

In order to describe the technical solution according to the utility model, reference will be made to the accompanying drawings and examples.

In this application, chemical mechanical polishing (Chemical Mechanical Polishing) is also referred to as chemical mechanical planarization (Chemical Mechanical Planarization), and wafers are also referred to as wafers, silicon chips, substrates or substrates (substrates), etc., and their meaning and actual function are equivalent.

As shown in fig. 1, an embodiment of the present utility model provides a wafer cleaning apparatus 1 for cleaning a wafer w, including: a case 11, a wafer supporting mechanism 12, two cleaning brushes 14, a cleaning brush driving mechanism 13, a liquid feeding mechanism 15, a liquid feeding assembly 16, and the like.

As shown in fig. 1, a process chamber is formed inside a housing 11, providing an environment for processing wafers w.

As shown in fig. 1, two brushes 14 are provided on both front and rear sides of the wafer w, respectively, and perform rolling brushing on the surface of the wafer w, wherein the two brushes 14 roll in opposite directions. The two brushes 14 are a first brush and a second brush, which are respectively provided on the front and rear sides of the wafer w to be cleaned, and can roll around their axes to contact the surface of the wafer w to be cleaned for brushing. The brush 14 is a cylindrical roller structure made of a material having good water absorption such as polyvinyl alcohol (PVA).

As shown in fig. 1, the cleaning brush 14 is kept in a wet state by continuously supplying liquid to the cleaning brush 14 through a liquid feeding mechanism 15 connected to one end of the cleaning brush 14. Wherein the brush 14 is made of a porous material capable of adsorbing a large amount of liquid. The liquid may be an acidic or basic solution or deionized water. The liquid inlet mechanism 15 is connected to the liquid inlet end of the brush 14, and fills the brush 14 with liquid. The brush 14 is soft after being filled with liquid, and the wafer w can be brushed, so that the brush 14 needs to be kept filled with liquid at any time during the cleaning process.

The brush 14 located at both sides of the wafer w may be moved in a horizontal direction to be away from or close to the wafer w. When the cleaning brush 14 is far away from the wafer w, a certain gap is reserved between the cleaning brush 14 and the wafer w, and the wafer w can be clamped by the wafer carrying manipulator to be taken away; when the brush 14 moves closer to the wafer w, the brush 14 contacts the wafer w to clean the surface of the wafer w.

As shown in fig. 1, the brush driving mechanism 13 is configured to drive two brushes 14 to move in opposite directions and clamp the wafer w at a certain angle for rolling and brushing. The brush driving mechanism 13 includes a brush rotation driving module and a brush horizontal driving module.

And the cleaning brush rotation driving module is used for supporting two cleaning brushes 14 positioned on two sides of the wafer w to be cleaned and driving the cleaning brushes 14 to rotate.

And a brush horizontal driving module connected with the brush rotation driving module to drive the brush rotation driving module and the brush 14 thereon to integrally move. The horizontal driving module of the cleaning brush can comprise a guide rail, a screw and a driving piece, wherein the guide rail and the screw are respectively connected with the rotary driving module of the cleaning brush so as to enable the rotary driving module of the cleaning brush to move along the guide rail under the driving of the screw, the driving piece is arranged at the end part of the screw, and the driving piece drives the screw to act, so that the cleaning brush supporting assembly and the cleaning brush 14 are driven to integrally move, and two ends of the cleaning brush 14 are enabled to be contacted with or far away from the wafer w at the same time. Further, the two ends of the cleaning brush 14 are respectively provided with screw rods, so that the movement distance of the two ends of the cleaning brush 14 can be respectively adjusted.

As shown in fig. 1, the liquid supply assembly 16 is configured to supply a cleaning liquid to the surface of the wafer w, and may specifically be an upper region of the surface of the wafer w above the cleaning brush 14. The supply angle of the cleaning liquid with respect to the surface of the wafer w is 5 DEG to 30 deg. The liquid supply assembly 16 is connected to a fluid source by a delivery line.

As shown in fig. 1, the wafer support mechanism 12 is used to support and position a wafer w and to drive the wafer w to rotate in a vertical plane. The wafer support mechanism 12 is fixed to the housing 11 and extends into the process chamber, and the wafer w to be cleaned is supported by the wafer support mechanism 12 and rotates in a vertical plane about a horizontal axis. The rotation speed of the wafer w is 1 to 200rpm, preferably 5 to 50rpm.

In one embodiment, wafer support mechanism 12 includes a plurality of roller assemblies. The plurality of roller assemblies may be specifically two driving wheel assemblies and driven wheel assemblies for supporting below the wafer w. The two driving wheel assemblies play a driving role, and the motor is utilized to rotationally drive the wafer w. As shown in fig. 1, the included angle formed by the two driving wheel assemblies relative to the center of the circle w of the wafer is smaller than 180 degrees. The driven wheel assembly is arranged between the two driving wheel assemblies, and plays roles of auxiliary support and speed measurement.

As shown in fig. 1, the drive wheel assembly and the driven wheel assembly are secured to the housing 11 and extend into the process chamber. The driving wheel assembly and the driven wheel assembly are arranged along the outline of the outer edge of the wafer w, the driven wheel assembly is positioned in the middle, and the driving wheel assembly is symmetrically arranged on two sides of the driven wheel assembly. The driving wheel assembly is provided with a movable wheel used for contacting with the wafer, the movable wheel is connected with a driving mechanism, the driving mechanism drives the movable wheel to rotate, and friction force between the outer edge of the wafer w and the movable wheel drives the wafer w to rotate around the axis of the wafer w.

Fig. 2 and 3 illustrate a roller assembly 20 for wafer cleaning according to an embodiment of the present utility model. The roller assembly 20 may be either a drive wheel assembly or a driven wheel assembly. The constituent structure of the roller assembly 20 is described below. As shown in fig. 3, each of the roller assemblies 20 penetrates through a sidewall of the case and protrudes into the case, a portion of the roller assembly 20 is located in the case for supporting a wafer, and another portion of the roller assembly 20 is located outside the case for being connected with a driving mechanism located outside the case or being fixed with the case, thereby forming a gap at a position penetrating the case. The presence of this gap allows the roller assembly 20 to be adjusted in position over a range to better accommodate the wafer.

As shown in fig. 3, the roller assembly 20 includes a movable wheel 21, a rotation shaft 22, a mounting seat 23, and a sealing assembly 24.

The movable wheel 21 is used for abutting the wafer and driving the wafer to rotate, and the wafer is limited in a clamping groove of the movable wheel 21 and rotates synchronously with the movable wheel 21 during cleaning.

The mounting seat 23 is used for being fixed with the box body, the mounting seat 23 penetrates through the side wall of the box body and stretches into the box body, the part, located outside the box body, of the mounting seat 23 is connected with the box body through the supporting piece, specifically, the mounting seat 23 is fixed to the supporting piece through the screws, and the supporting piece and the box body are fixed to the same base through the screws respectively. A gap is arranged between the mounting seat 23 and the box body. The gap between the mounting seat 23 and the box body is sealed by a sealing assembly 24.

The rotating shaft 22 is rotatably disposed in the mounting seat 23, and one end of the rotating shaft 22 is connected to the movable wheel 21 to drive the movable wheel 21 to rotate. The rotary shaft 22 is sleeved with a bearing. The mounting seat 23 is sleeved on the outer peripheral side of the rotary shaft 22, and the mounting seat 23 and the rotary shaft 22 are connected through a bearing. When the roller assembly 20 is a driving wheel assembly, the driving mechanism is connected to the rotating shaft 22 to drive the rotating shaft 22 to rotate.

The outer ring 27, the inner ring 28, the inward, the outward, and the inward-outward are referred to as the rotation shaft 22, and the inner and the outer are referred to as the inner and the outer, respectively, which are closer to the rotation shaft 22. The upper and lower directions are referred to in the drawings of the specification.

As shown in fig. 3, a sealing assembly 24 is fixed to the mounting seat 23 and the case, respectively, for sealing a gap between the mounting seat 23 and the case. The seal assembly 24 comprises a seal gasket 25, an outer pressure ring 27 and an inner pressure ring 28, wherein the inner pressure ring 28 fixes the seal gasket 25 and the mounting seat 23, the outer pressure ring 27 fixes the seal gasket 25 and the box body, and the inner pressure ring 28 is positioned on the inner side of the outer pressure ring 27. The gasket 25 is annular and is disposed around the mounting seat 23. The gasket 25 is an elastic material.

As shown in fig. 2 and 3, in one embodiment of the present utility model, the outer pressure ring 27 and the inner pressure ring 28 are both annular. The periphery of the outer pressing ring 27 is provided with a plurality of screw holes, and the outer pressing ring 27 is fixed on the side wall of the box body by screws, so that the annular outer area of the sealing gasket 25 is pressed by the outer pressing ring 27 and fixed on the side wall of the box body, and the outer area of the sealing gasket 25 is positioned between the outer pressing ring 27 and the side wall of the box body. A circular hole is formed in the middle of the sealing gasket 25, and the part of the mounting seat 23 with external threads passes through the circular hole of the sealing gasket 25 and then passes through the inner pressure ring 28. The inner region of the gasket 25 is located between the inner pressure ring 28 and the mounting seat 23. The female lock 26 having the female screw is screwed with the portion of the mount 23 having the male screw. As shown in fig. 3, the lock nut 26, the inner pressure ring 28, the gasket 25 and the mount 23 are sequentially seen from the direction of the inside of the case toward the side wall of the case, and the lock nut 26 is screwed in to press and fix the inner pressure ring 28 and the gasket 25 to the front end of the mount 23.

The gasket 25 of the roller assembly 20 is usually made of rubber, and some special rubbers have certain chemical resistance, but because cleaning liquid is often sprayed in the process chamber, the surface environment of the gasket 25 is alternately changed in water, chemical liquid and air environment for a long time, so that the gasket 25 is easy to release and drop organic pollutants into a liquid medium, dirty water containing the pollutants can pollute the movable wheel 21, and further the cleaned wafer is polluted, especially the crystal edge. In order to solve the problem that the movable wheel 21 is easily contaminated, the present utility model makes the following modifications to the seal assembly 24.

As shown in fig. 2 and 3, in one embodiment of the present utility model, the upper portion of the outer pressure ring 27 has a water blocking structure 271. When the wafer cleaning device is used for cleaning, liquid flowing downwards from the upper part of the box body can be polluted by contacting the sealing gasket 25 from the upper edge, and the water retaining structure 271 is arranged at the upper part of the outer pressure ring 27, so that the liquid coming from the upper part can be blocked, and the polluted liquid can be prevented from polluting the movable wheel 21 again to influence the wafer cleaning effect.

In one embodiment, the water blocking structure 271 includes a water blocking eave 272 formed to extend outwardly from the outer peripheral edge of the outer pressure ring 27 and a first groove 273 formed between the water blocking eave 272 and the case. In one embodiment, the water stop edge 272 may be formed by extending the entire edge of the outer ring 27. In another embodiment, the water blocking eave 272 may be formed by extending part of the edge of the outer ring 27 outwards. The water blocking eaves 272 may extend vertically upward or may extend obliquely upward, with the direction of inclination being inclined in a direction from the inside toward the movable wheel 21. In the example shown in fig. 2, the water blocking eave 272 is formed by extending upward from the outer edge of the upper half of the outer pressure ring 27 away from the case. The water blocking eave 272 can block the liquid from above. Accordingly, a first groove 273 is formed between the water blocking eave 272 and the box body or between the water blocking eave 272 and the sealing gasket 25, and the outer circumferential surfaces of the water blocking eave 272 and the outer pressing ring 27, because the bottom surface of the first groove 273 is arc-shaped with high middle and low two sides, the first groove 273 can collect the liquid blocked by the water blocking eave 272 and drain downwards from two sides, that is to say, under the combined action of the water blocking eave 272 and the first groove 273, the polluted liquid can flow downwards along the outer circumferential surfaces of the outer pressing ring 27, so that the movable wheels 21 and the wafers are prevented from being polluted by pollutants.

As shown in fig. 2, in one embodiment, the water blocking eave 272 has a half-moon structure that gradually narrows in a high-to-low direction, in other words, the width of the water blocking eave 272 gradually decreases from top to bottom.

Based on the structure of the outer pressure ring 27, the liquid coming from the outer circumferential direction of the roller assembly 20 contacts the periphery of the sealing gasket 25, and the liquid containing pollutants is guided to flow away towards two sides along the outer circumferential surface of the outer pressure ring 27 through the first groove 273 formed between the half-moon-shaped water retaining eave 272 at the top of the outer pressure ring 27 and the side wall of the box body, so that the phenomenon that the liquid accumulated above the outer pressure ring 27 is transferred onto the movable wheel 21 from the front surface of the outer pressure ring 27 is avoided, and the movable wheel 21 and the wafer are prevented from being polluted.

In one embodiment, as shown in fig. 2, the lower portion of the outer pressure ring 27 has a drain structure 274 for facilitating drainage and preventing excessive accumulation of liquid on the bottom and onto the side movable wheel 21. In the example shown in fig. 2, the drainage structure 274 is a notch in the bottom of the outer pressure ring 27. Alternatively, in another embodiment, the drain 274 may be a groove in the bottom surface of the outer pressure ring 27, which also allows the liquid to drain.

As shown in fig. 3, in one embodiment, the inner peripheral surface of the outer pressure ring 27 is provided with a first guiding inclined surface 275, the first guiding inclined surface 275 is inclined from outside to inside in a direction approaching the case, and the first guiding inclined surface 275 can guide the liquid flowing to the surface of the outer pressure ring 27 downward, so that excessive contamination of the movable wheel 21 beside due to capillary action on the inner peripheral surface of the outer pressure ring 27 can be avoided.

As shown in fig. 2 and 3, in one embodiment of the present utility model, a gap is formed between the inner pressure ring 28 and the outer pressure ring 27, so that flexible deformation of the gasket 25 can be accommodated to facilitate the adjustment of the position of the roller assembly 20. When the contact position between the movable wheel 21 and the wafer is adjusted, the size of the gap between the mounting seat 23 and the case changes everywhere, thereby causing the flexible deformation of the gasket 25, and the size of the gap between the inner pressure ring 28 and the outer pressure ring 27 changes accordingly.

As shown in fig. 2 and 3, in one embodiment of the present utility model, the inner pressure ring 28 has a water guiding structure 281. Liquid flowing between the outer pressure ring 27 and the inner pressure ring 28 during cleaning can be collected by the water guide structure 281 and drained downwards, so that excessive accumulation of the outer peripheral surface of the inner pressure ring 28 is avoided to pollute the movable wheel 21.

As shown in fig. 3, the water guide structure 281 is a water guide eave 282 extending obliquely outward from the outer peripheral edge of the inner pressure ring 28 toward the movable wheel 21 side. The water guiding eave 282 may include an inclined portion inclined from inside to outside toward the movable wheel 21 direction and a vertical portion extending vertically, specifically, extending outwardly from an edge of the inclined portion.

In one embodiment, as shown in FIG. 3, the water guiding eave 282 is annular. In another embodiment, the water guiding eave 282 may be semi-annular or partially annular, so long as it is capable of collecting and draining downwardly as liquid flows into the gap between the inner and outer pressure rings 28, 27.

As shown in fig. 3, in one embodiment, the outer peripheral edge of the water guiding eave 282 is provided with a second guiding slope 283. The second guide inclined surface 283 is inclined from the outside to the inside in a direction approaching the case, and the second guide inclined surface 283 guides the liquid flowing between the outer pressure ring 27 and the inner pressure ring 28, thereby preventing the movable wheel 21 from being contaminated by the accumulated liquid on the upper peripheral portion of the water guiding eave 282.

Based on the above-mentioned structures of the inner pressure ring 28 and the outer pressure ring 27, the liquid in other directions should contact the surface of the gasket 25 in the process chamber, and can only pass through the gap between the second guiding inclined surface 283 of the inner pressure ring 28 and the first guiding inclined surface 275 of the outer pressure ring 27, and the liquid entering the gap is confined in the annular semi-enclosed space 284 between the outer pressure ring 27 and the inner pressure ring 28, and flows out from the drainage structure 274 along the bottom of the annular semi-enclosed space 284, for example: the liquid flowing along the top of the outer pressure ring 27 to the inner peripheral surface of the outer pressure ring 27 enters the inner bottom surface of the annular semi-closed space 284 along the first guide inclined surface 275 of the outer pressure ring 27 or the second guide inclined surface 283 of the inner pressure ring 28, and the liquid accumulated on the inner bottom surface drains downward along the annular groove surrounded by the water guiding eave 282 and the sealing gasket 25 in the annular semi-closed space 284, and flows out of the water draining structure 274. The contamination contacting the surface of the gasket 25 cannot contact the lock nut 26 in the whole course, so that the possibility that the contamination flows to the movable wheel 21 through the lock nut 26 and the rotating shaft 22 is eliminated; in addition, since the first guide inclined surface 275 and the drain structure 274 are provided at the bottom of the outer pressing ring 27, there is no accumulation of dirty water on the lower inner peripheral surface of the outer pressing ring 27.

Further, in one embodiment, the outer surface of the movable wheel 21 is provided with a hydrophobic coating or a super-hydrophobic coating, such as polytetrafluoroethylene, polyperfluoroethylene propylene, and the like, so that the surface of the movable wheel 21 is not easy to be contaminated with liquid, and the surface of the movable wheel 21 is prevented from retaining pollutants.

In sum, the outer pressure ring 27 and the inner pressure ring 28 are matched with each other, so that liquid flowing through the sealing gasket 25 can be guided to avoid the nut 26, thereby cutting off a path of the liquid contacting the sealing gasket 25 and polluted by the sealing gasket to be transmitted to the movable wheel 21, blocking a transmission path of pollutants between a pollution risk component and a wafer to be cleaned, solving the problem that the cleaned wafer is polluted randomly by dirty water of the sealing gasket 25 when the wafer is vertically brushed, remarkably improving the cleanliness near the edge of the wafer, and greatly improving the effect and stability of the cleaning process.

The drawings in the present specification are schematic views, which assist in explaining the concept of the present utility model, and schematically show the shapes of the respective parts and their interrelationships. It should be understood that for the purpose of clearly showing the structure of various parts of embodiments of the present utility model, the drawings are not drawn to the same scale and like reference numerals are used to designate like parts in the drawings.

In the description of the present specification, reference to the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the utility model. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the present utility model have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the utility model, the scope of which is defined by the claims and their equivalents.

Claims (12)

1. A roller assembly coupled to a housing for wafer cleaning, the roller assembly comprising a movable wheel, a rotatable shaft, a mounting seat, and a seal assembly; the sealing component is respectively fixed with the mounting seat and the box body and is used for sealing a gap between the mounting seat and the box body; the sealing assembly comprises a sealing gasket, an outer pressing ring and an inner pressing ring, the inner pressing ring fixes the sealing gasket with the mounting seat, the outer pressing ring fixes the sealing gasket with the box body, and the inner pressing ring is positioned on the inner side of the outer pressing ring.

2. The roller assembly of claim 1, wherein an upper portion of the outer pressure ring has a water blocking structure.

3. The roller assembly of claim 2, wherein the water blocking structure includes a water blocking ledge extending outwardly from the peripheral edge of the outer pressure ring and a first groove formed between the water blocking ledge and the housing.

4. A roller assembly according to claim 3, wherein the water retaining eaves is of a half-moon configuration tapering in a high to low direction.

5. The roller assembly of any one of claims 1 to 4, wherein a lower portion of the outer pressure ring has a drainage structure.

6. The roller assembly of claim 5, wherein the drainage structure is a notch in the bottom of the outer pressure ring.

7. The roller assembly according to any one of claims 1 to 4, wherein an inner circumferential surface of the outer pressing ring is provided with a first guide slope.

8. The roller assembly of any one of claims 1 to 4, wherein the inner pressure ring has a water guiding structure.

9. The roller assembly of claim 8, wherein the water guiding structure is a water guiding eave extending obliquely outward from an outer peripheral edge of the inner pressure ring toward one side of the movable wheel.

10. The roller assembly of claim 9, wherein the water guiding eave is ring-shaped.

11. A roller assembly according to claim 9 or claim 10, wherein the peripheral edge of the water guiding eave is provided with a second guiding ramp.

12. The roller assembly of any one of claims 1 to 4, wherein the rotating shaft is rotatably disposed in the mounting base, and one end of the rotating shaft is connected to the movable wheel.