CN214226893U

CN214226893U - Wafer preprocessing device

Info

Publication number: CN214226893U
Application number: CN202120512185.XU
Authority: CN
Inventors: 史蒂文·贺·汪; 林鹏鹏
Original assignee: Silicon Dense Core Plating Haining Semiconductor Technology Co ltd; Xinyang Guimi Shanghai Semiconductor Technology Co ltd
Current assignee: Silicon Dense Core Plating Haining Semiconductor Technology Co ltd; Xinyang Guimi Shanghai Semiconductor Technology Co ltd
Priority date: 2021-03-10
Filing date: 2021-03-10
Publication date: 2021-09-17
Anticipated expiration: 2031-03-10

Abstract

The utility model discloses a wafer preprocessing device, it includes the cell body subassembly, is equipped with the tray in the cell body subassembly, and on the tray can be arranged in to the wafer, the tray is portable to when the wafer gets for the cell body subassembly to put, the tray removes to closing on or being located the horizontality. The utility model provides a wafer preprocessing device carries out a series of settings through the structure to it, place the tray of wafer through removing promptly, make it have one can make the wafer close on or be located the position of horizontality, carry out getting of wafer under this state and put when operating, because the limited degree in space reduces, convenient operation more, no matter artificial placing or manipulator operation under the horizontality, the condition emergence that can not have the wafer and can drop perpendicularly and take place the damage can not exist, can make the wafer slowly slide into the tray through the promotion mode even, consequently, the effect that makes the wafer guarantee to place safely has been played.

Description

Wafer preprocessing device

Technical Field

The utility model relates to a wafer preprocessing device.

Background

Wafers, which are widely used in the fabrication of integrated circuits. The surface of the wafer which is not pretreated may have fine grooves, and in the subsequent electroplating operation, a great amount of bubbles are generated due to insufficient contact between the electroplating solution and the wafer, so that the electroplating effect of the wafer is greatly influenced.

In order to solve the above problems, generally, when a wafer is pretreated, the wafer is placed in a process tank, a tray inside the process tank can contain the wafer, so that the wafer is finally placed in an action position in the tank through the positioning and abutting action of the tray when the wafer is placed, then the process tank is sealed, and then the process tank is vacuumized immediately. Through the process, the fine grooves on the surface of the wafer are filled with water, namely the surface gas is pumped out, so that the full contact between the electroplating solution and the wafer can be ensured to the maximum extent during the subsequent electroplating operation, and a large amount of bubbles are avoided.

However, the process tank for placing the wafer is usually kept in a vertical state, and the opening of the process tank faces upward to ensure a certain sealing effect in a vacuum state, so that when the wafer is placed, the wafer can be only manually placed in the tank or vertically placed in the tank through a mechanical gripper or a sucker. The inner space of the tank body is narrow, and in a vertical placement state, the operation space and the angle are limited, so that the edge of the wafer is easily collided, and the quality of the wafer is influenced.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model is that the operating space for placing the wafer among the prior art is limited in order to overcome, gets under the vertical state and puts the defect that drops easily and lead to the bottom to collide with, provides a wafer preprocessing device.

The utility model discloses an above-mentioned technical problem is solved through following technical scheme:

the utility model provides a wafer preprocessing device, its includes the cell body subassembly, be equipped with the tray in the cell body subassembly, the wafer can be arranged in on the tray, its characterized in that, the tray is portable to when the wafer for the cell body subassembly is got and is put, the tray removes to closing on or is located the horizontality.

Through carrying out above-mentioned setting to this wafer preprocessing device, place the tray of wafer through removing promptly, make it have one can make the wafer close on or be located the position of horizontality, carry out getting of wafer under this state and put when operating, because the limited degree in space reduces, more convenient operation, no matter artificial placing or manipulator operation under the horizontality, the condition emergence that can not have the wafer and can drop perpendicularly and take place the damage, can make the wafer slowly slide into the tray through promoting the mode even, consequently, the effect that makes the wafer guarantee to place safely has been played.

Preferably, the wafer pretreatment device further comprises a support base, the tank assembly is arranged on the support base, and the tank assembly and the tray can move synchronously relative to the support base;

when the wafer is taken and placed relative to the tank body assembly, the direction of an opening communicated to the outside of the tank body assembly is close to or in a horizontal state. Through directly setting up the cell body subassembly on the supporting seat, make the cell body subassembly portable for the supporting seat to the realization makes the tray that is located the inside of cell body subassembly close on or is located the horizontality, and, the outside opening orientation of cell body subassembly intercommunication also is for closing on or being located the horizontality, thereby makes things convenient for operating personnel to take out or place, and this kind of mode of setting is convenient for simplify overall structure, realizes the bulk movement of cell body subassembly promptly and can satisfy above-mentioned effect, and it is also comparatively convenient to operate.

Preferably, the wafer pretreatment device further comprises a driving assembly, the driving assembly comprises a motor and a transmission mechanism, the transmission mechanism comprises a worm wheel and a worm which are meshed with each other, the worm is connected to the motor, and the worm wheel is connected to the tank assembly. This cell body subassembly realizes the removal for the supporting seat through the drive mechanism that worm wheel and worm are constituteed, worm wheel and worm cooperation can act on the rotary motion of motor to the worm, the rotation of worm drives the worm wheel cooperation then and rotates, because the worm wheel is connected to the cell body subassembly, so the rotation of worm wheel drives the whole rotation of cell body subassembly, thereby the opening that makes originally to be located the top removes to the side of orientation, thereby make things convenient for operating personnel to carry out getting of wafer and put, this linkage mode simple structure, easily operation.

Preferably, the trough body assembly is erected on the supporting seat through a fixing shaft, and the worm wheel is fixed and sleeved at one end of the fixing shaft. The fixed shaft is used for supporting the groove body assembly, and meanwhile, the fixed shaft is conveniently connected with a worm wheel of the transmission mechanism in a matched mode to perform rotary motion.

Preferably, the wafer preprocessing device further comprises a bearing mechanism, the tank body assembly is connected with the supporting seat through the bearing mechanism, the bearing mechanism comprises a bearing support and a bearing, an outer ring of the bearing is fixed on the bearing support, and an inner ring of the bearing is fixed with the worm wheel. Bearing mechanism is used for realizing the reciprocal anchorage between cell body subassembly and the supporting seat, simultaneously because the effect of bearing can make the cell body subassembly for bearing, overturn for the supporting seat promptly, and drive mechanism realizes the transmission of upset in-process through the inner circle of turbine and bearing simultaneously to realize the rotation of cell body subassembly, this kind of mode makes the cell body subassembly remain stable better in the transmission process.

Preferably, the tray is movable relative to the tank assembly, and the tray can move from the tank assembly to the outside of the opening of the tank assembly. The tray is portable for the cell body subassembly, under the unchangeable condition in the position of cell body subassembly or direction promptly, can realize the change of getting the mode of putting the wafer through the position that changes the tray, the tray removes to the opening outside of cell body subassembly from the cell body subassembly is inside, operating personnel is when using, directly place the wafer from the position that the opening outside corresponds to the tray, because the tray closes on or is located the horizontality, so not only operating space is because the grow that shifts out of tray, still because the horizontality makes placing of wafer change the operation more easily, no matter artificial placing or mechanical hand operation, the horizontality all can make placing of wafer safer steady.

Preferably, a guide mechanism is arranged in the tank body assembly, the guide mechanism extends towards the opening, the tray can relatively move along the extending direction of the guide mechanism, and the tray is rotatably connected with the guide mechanism. The setting of guiding mechanism plays the effect that makes interconnect between tray and the cell body subassembly on the one hand, and on the other hand, guiding mechanism provides the guide effect for the removal of tray, makes the tray change its position state through guiding mechanism's guide until moving the open side of cell body subassembly, and is spacing to it simultaneously, has realized the final user state of being convenient for to place.

Preferably, the guiding mechanism includes a sliding guide rail and a connecting guide bar that are movably connected to each other, the connecting guide bar extends along the extending direction of the sliding guide rail, the connecting guide bar can slide in the extending direction of the sliding guide rail, and one end of the connecting guide bar is rotatably connected to the tray. The setting of connecting the conducting bar makes the tray can remove to the opening direction of cell body subassembly to through the rotatable horizontality that realizes final tray between connecting conducting bar and the tray, it is narrow and small that the cell body subassembly inner space has been overcome to whole process, is unfavorable for the problem of the position change of tray, and the structure setting is comparatively ingenious.

Preferably, a positioning flange is arranged at the bottom of the tray, the positioning ledge protrudes out of the surface of the tray for receiving the wafer, and one end of the wafer can abut against the side surface of the positioning flange. The setting of location flange has guaranteed that the wafer has the effect of a side butt after placing, makes it fixed at tray surface holding position, can not appear sliding, has also protected the edge of wafer simultaneously can not take place to collide with other positions of cell body subassembly, like inside wall department.

Preferably, the center of gravity of the tray is located on a portion of the tray that can protrude outside the opening of the tank assembly. The part of the tray, the center of gravity of which is located outside the protruding opening, is to achieve that the tray has a tendency to tilt towards the outside in a state close to horizontal, rather than sliding back into the interior of the chute assembly.

Preferably, the inner side of the opening is provided with a limiting structure protruding out of the inner side surface of the tank body assembly, and the tray can rotate until one end face of the tray abuts against one side of the limiting structure. The setting of limit structure cooperation tray focus makes the tray under the motion trend of outside facing slope, can carry out final position's assurance through limit structure, avoids the tray slope too serious, can't make the wafer normally get on the contrary and put.

On the basis of the common knowledge in the field, the above preferred conditions can be combined at will to obtain the preferred embodiments of the present invention.

The utility model discloses an actively advance the effect and lie in:

the utility model provides a wafer preprocessing device carries out a series of settings through the structure to it, place the tray of wafer through removing promptly, make it have one can make the wafer close on or be located the position of horizontality, carry out getting of wafer under this state and put when operating, because the limited degree in space reduces, convenient operation more, no matter artificial placing or manipulator operation under the horizontality, the condition emergence that can not have the wafer and can drop perpendicularly and take place the damage can not exist, can make the wafer slowly slide into the tray through the promotion mode even, consequently, the effect that makes the wafer guarantee to place safely has been played.

Drawings

Fig. 1 is a schematic structural view of a wafer pretreatment apparatus according to embodiment 1 of the present invention.

Fig. 2 is a partial structural view of a portion a in fig. 1.

Fig. 3 is a schematic structural diagram of a wafer pretreatment apparatus according to embodiment 1 of the present invention in another state.

Fig. 4 is a schematic sectional view of a tank assembly of a wafer pretreatment apparatus according to embodiment 2 of the present invention.

Fig. 5 is a schematic cross-sectional view of the trough assembly of embodiment 2 of the present invention in another state.

Description of reference numerals:

tank assembly 1

Tray 11

Positioning flange 11a

Opening 12

Supporting seat 2

Drive assembly 3

Motor 31

Worm wheel 32

Worm 33

Fixed shaft 4

Bearing support 51

Bearing 52

Guide mechanism 6

Slide rail 61

Connecting bar 62

Limiting structure 7

Alarm liquid level sensing device 8

Water inlet 9

Wafer 10

Detailed Description

The present invention will be more clearly and completely described below by way of two preferred embodiments in conjunction with the accompanying drawings, which do not limit the scope of the embodiments described herein.

Example 1

As shown in fig. 1 to 3, the embodiment provides a wafer preprocessing device, which includes a tank assembly 1, a tray is disposed inside the tank assembly 1, a wafer is placed on the tray, and the tray can move along with the tank assembly 1, when the wafer is taken and placed relative to the tank assembly 1, the tray moves to a close or horizontal state along with the tank assembly 1 in a turning movement manner.

This wafer preprocessing device places the tray of wafer through removing, make it have one can make the wafer close to or be located the position of horizontality, another position state that shows in fig. 3 promptly, when carrying out the operation of getting of wafer under this position state, the position state that the space restricted degree is normal work relative to wafer preprocessing device is littleer relatively, it is more convenient to get and put the operation, no matter artificial placing or manipulator operation under the horizontality, the condition emergence that can not have the wafer and can drop perpendicularly and take place the damage, can make the wafer slowly slide into the tray through the mode of promotion even, consequently, played the effect that makes the wafer guarantee to place safely.

Further, in this embodiment, the wafer preprocessing device further includes a supporting seat 2, the tank assembly 1 is erected on the supporting seat 2, the tank assembly 1 and the tray are synchronously turned over and moved relative to the supporting seat 2, and when the wafer is taken and placed relative to the tank assembly 1, the tank assembly 1 is communicated to the outside opening 12 and faces to the adjacent or horizontal state. Through directly erectting cell body subassembly 1 on supporting seat 2, make cell body subassembly 1 portable for supporting seat 2, thereby the realization makes the tray that is located cell body subassembly 1 inside close on or is located the horizontality, and, under this kind of synchronous movement's mode, cell body subassembly 1 communicates outside opening 12 orientation also for closing on or being located the horizontality, thereby make things convenient for operating personnel to take out or place, this kind of mode sets up, be convenient for simplify overall structure, realize cell body subassembly 1's bulk movement promptly and can satisfy above-mentioned effect, it is also comparatively convenient to operate.

The wafer pretreatment device also comprises a driving component 3, and the driving component 3 is erected on the supporting seat 2. The driving assembly 3 comprises a motor 31 and a transmission mechanism, the transmission mechanism comprises a worm wheel 32 and a worm 33 which are meshed with each other, the worm 33 is connected to the motor 31, and the worm wheel 32 is connected to the trough body assembly 1. This cell body subassembly 1 realizes the removal for supporting seat 2 through the drive mechanism that worm wheel 32 and worm 33 constitute, worm wheel 32 and the cooperation of worm 33 can act on motor 31's rotary motion to worm 33, the rotation of worm 33 drives worm wheel 32 cooperation then and rotates, because worm wheel 32 is connected to cell body subassembly 1, so the rotation of worm wheel 32 drives cell body subassembly 1 and wholly rotates, thereby the messenger originally moves to the orientation side at opening 12 that is located the top, thereby make things convenient for operating personnel to carry out getting of wafer and put, this linkage mode simple structure, easy to operate.

In this embodiment, the trough assembly 1 is erected on the supporting base 2 through a fixing shaft 4 and a bearing mechanism, the trough assembly 1 and the supporting base 2 are connected through the bearing mechanism, the bearing mechanism includes a bearing support 51 and a bearing 52, an outer ring of the bearing 52 is fixed on the bearing support 51, an inner ring of the bearing 52 is fixed with the worm wheel 32, and an inner ring of the bearing 52 is sleeved on one end of the fixing shaft 4. The fixed shaft 4 and the bearing support 51 are used for supporting the trough body assembly 1, and meanwhile, the fixed shaft is conveniently matched and connected with the worm wheel 32 of the transmission mechanism to perform rotary motion. Simultaneously because the effect of bearing 52 can make cell body subassembly 1 overturn for bearing 51, promptly for supporting seat 2, drive mechanism realizes the transmission in the upset process through the inner circle of turbine and bearing 52 connection simultaneously to realize the rotation of cell body subassembly 1, this kind of mode makes cell body subassembly 1 remain stable better in the transmission process.

Of course, in other embodiments, the transmission can be realized by directly connecting the fixed shaft 4 to the center of the turbine, and the fixed shaft 4 is mounted on the supporting seat 2. Similarly, the inner ring of the bearing 52 can be fixed on the side wall of the tank assembly 1 by using only the bearing mechanism, and the two can be fixed to each other, in this state, the movement of the transmission assembly can also directly drive the tank assembly 1 to rotate, that is, the connection mode between the tank assembly 1 and the support base 2 or the transmission mechanism is not limited, as long as the transmission of the rotation movement to the tank assembly 1 can be ensured.

When an operator uses the wafer pretreatment device, the transmission mechanism is controlled through the external control system, the motor 31 is driven, the worm gear 32 and the worm 33 are driven to move, the tank body assembly 1 is made to rotate from a vertical state to a horizontal state gradually along with the movement of the transmission mechanism until the tank body assembly is rotated to an angle which is convenient for the operator to take and place the wafer, in the state, the operator takes and places the wafer manually or mechanically, the transmission mechanism is continuously controlled after the taking and the placing are completed, the initial state is recovered, and then subsequent sealing and vacuumizing operations are performed, namely, water filling operation is performed on the inside of the tank body assembly 1 through the water inlet 9 at the bottom of the tank body assembly 1 until the liquid level reaches the position of the alarm liquid level sensing device, and then sealing and vacuumizing are performed.

Example 2

As shown in fig. 4-5, the apparatus for pre-processing a wafer 10 in this embodiment is substantially the same as the first embodiment except that: the tray 11 in this embodiment is movable relative to the tank assembly 1.

In this embodiment, the tray 11 can move from inside the tank assembly 1 to outside the opening 12 of the tank assembly 1. The tray 11 is movable relative to the tank assembly 1, that is, under the condition that the position or direction of the tank assembly 1 is not changed, the taking and placing manner of the wafer 10 can be changed by changing the position of the tray 11, the tray 11 moves from the inside of the tank assembly 1 to the outside of the opening 12 of the tank assembly 1, when an operator uses the wafer processing device, the wafer 10 is directly placed from the outside of the opening 12 corresponding to the position of the tray 11, and because the tray 11 is close to or located in a horizontal state, that is, in another state shown in fig. 5, not only the operation space is enlarged due to the removal of the tray 11, but also the placement of the wafer 10 is easier to operate due to the horizontal state, and the horizontal state can make the placement of the wafer 10 safer and more stable no matter whether the tray is manually placed or manually operated by a mechanical hand.

Further, a guide mechanism 6 is arranged in the tank body assembly 1, the guide mechanism 6 extends towards the opening 12, the tray 11 can move relatively along the extending direction of the guide mechanism 6, and the tray 11 is rotatably connected with the guide mechanism 6. The setting of guiding mechanism 6 plays the effect that makes interconnect between tray 11 and the cell body subassembly 1 on the one hand, and on the other hand, guiding mechanism 6 provides the guide effect for the removal of tray 11, makes tray 11 change its position state through guiding mechanism 6's guide until moving the opening 12 outside of cell body subassembly 1, and is spacing to it simultaneously, has realized the final user state of being convenient for to place.

The guiding mechanism 6 comprises a sliding guide rail 61 and a connecting guide bar 62 which are movably connected with each other, the connecting guide bar 62 extends along the extending direction of the sliding guide rail 61, the connecting guide bar 62 can slide in the extending direction of the sliding guide rail 61, and one end of the connecting guide bar 62 is rotatably connected with the tray 11. Specifically, fixed connection between sliding guide 61 and cell body subassembly 1, sliding guide 61 can be followed and set up and fix towards the opening 12 direction extension of cell body group price from the bottom of cell body subassembly 1, it is fixed to preferably use bolted connection's mode, convenient to change dismantlement, it extends the setting to connect gib 62 along sliding guide 61's extending direction, make tray 11 can move to cell body subassembly 1's opening 12 direction, and finally when tray 11 moves to the opening 12 outside of cell body group price, through connecting rotatable realization final tray 11 between gib 62 and the tray 11 close on or be located the horizontally state, the inside space of cell body subassembly 1 has been overcome to whole process is narrow and small, be unfavorable for the problem of the position change of tray 11, the structure sets up comparatively ingeniously.

In addition, the center of gravity of the tray 11 is located on a portion of the tray 11 that can protrude outside the opening 12 of the tank body assembly 1. The portion of the tray 11 where the center of gravity is located outside the protrusion opening 12 is to achieve a tendency for the tray 11 to tilt toward the outside in a state close to horizontal, rather than sliding back into the interior of the chute body assembly 1. Further, the inner side of the opening 12 of the tank body assembly 1 is also provided with a limiting structure 7, the limiting structure 7 protrudes out of the inner side face of the tank body assembly 1, and the tray 11 can rotate to one end face of the tray 11 to abut against one side of the limiting structure 7. The arrangement of the limiting structures 7 is matched with the arrangement of the gravity center of the tray 11, so that the tray 11 can be guaranteed to be in the final position through the limiting structures 7 under the movement trend of inclining towards the outside, and the situation that the tray 11 inclines too severely, and the wafer 10 cannot be normally taken and placed is avoided.

In this embodiment, the bottom of the tray 11 is further provided with a positioning flange 11a, the positioning flange protrudes out of the surface of the tray 11 for receiving the wafer 10, and one end of the wafer 10 can abut against the side surface of the positioning flange 11 a. The setting of location flange 11a has guaranteed that wafer 10 has the effect of a side butt after placing, makes it fixed at 11 surface holding position of tray, can not appear sliding, has also protected wafer 10's edge simultaneously can not and cell body subassembly 1's other positions, takes place to collide with like inside wall department.

Similarly, when an operator uses the wafer pretreatment device, the operator manually pulls the tray 11 to move towards the outside of the tank assembly 1, and the tray 11 moves along with the extending direction of the sliding guide 61 in the pulling process until at least a part of the tray moves to the outside of the opening 12 of the tank assembly 1, then rotates relative to the connecting point of the connecting guide bar 62, gradually rotates to be close to or in a horizontal state, and is limited by the limiting structure 7 to prevent the tray from rotating continuously. In this state, the operator manually or mechanically operates to pick and place the wafer 10, and after the picking and placing is completed, the tray 11 is pushed to slide back to the position inside the tank assembly 1 under the limitation of the guide mechanism 6, namely, to return to the initial state, and then subsequent sealing and vacuumizing operations are performed, namely, water filling operation is performed on the inside of the tank assembly 1 through the water inlet 9 at the bottom of the tank assembly 1 until the liquid level reaches the position of the alarm liquid level sensing device 8, and then sealing and vacuumizing are performed.

In addition, in other embodiments, the rotation of the trough assembly 1 and the movement of the tray 11 relative to the trough assembly 1 can be combined for operation and setting, so as to meet different use requirements and conditions.

Although specific embodiments of the present invention have been described above, it will be understood by those skilled in the art that this is by way of example only and that the scope of the invention is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the spirit and the principles of the present invention, and these changes and modifications are all within the scope of the present invention.

Claims

1. The utility model provides a wafer preprocessing device, its includes the cell body subassembly, be equipped with the tray in the cell body subassembly, the wafer can be arranged in on the tray, its characterized in that, the tray is portable to when the wafer for the cell body subassembly is got and is put, the tray removes to closing on or is located the horizontality.

2. The wafer pretreatment apparatus as recited in claim 1, further comprising a support base, wherein the tank assembly is mounted on the support base, and the tank assembly and the tray are movable synchronously with respect to the support base;

when the wafer is taken and placed relative to the tank body assembly, the direction of an opening communicated to the outside of the tank body assembly is close to or in a horizontal state.

3. The wafer pretreatment apparatus as recited in claim 2, further comprising a drive assembly, the drive assembly comprising a motor and a transmission mechanism, the transmission mechanism comprising a worm gear and a worm that are engaged with each other, the worm being connected to the motor, the worm gear being connected to the tank assembly.

4. The wafer pretreatment device as recited in claim 3, wherein the tank assembly is mounted on the support base by a fixing shaft, and the worm wheel is fixed and sleeved on one end of the fixing shaft.

5. The wafer pretreatment device as recited in claim 3, further comprising a bearing mechanism, wherein the tank assembly is connected to the support base through the bearing mechanism, the bearing mechanism comprises a bearing support and a bearing, an outer ring of the bearing is fixed to the bearing support, and an inner ring of the bearing is fixed to the worm wheel.

6. The wafer pretreatment apparatus as set forth in claim 1 or 2, wherein the tray is movable relative to the tank assembly, the tray being movable from inside the tank assembly to outside the opening of the tank assembly.

7. The wafer pretreatment apparatus as recited in claim 6, wherein a guide mechanism is disposed in the tank assembly, the guide mechanism extends toward the opening, the tray is capable of moving relative to the guide mechanism along the extension direction of the guide mechanism, and the tray is rotatably connected to the guide mechanism.

8. The wafer preprocessing device as claimed in claim 7, wherein the guiding mechanism comprises a sliding guide rail and a connecting guide bar movably connected with each other, the connecting guide bar extends along an extending direction of the sliding guide rail, the connecting guide bar can slide in the extending direction of the sliding guide rail, and one end of the connecting guide bar is rotatably connected with the tray.

9. The wafer pretreatment apparatus as recited in claim 5, wherein a positioning flange is disposed at a bottom of the tray, the positioning flange protrudes from a surface of the tray for receiving the wafer, and one end of the wafer can abut against a side surface of the positioning flange.

10. The wafer pretreatment apparatus as recited in claim 5, wherein a center of gravity of the tray is located on a portion of the tray that can protrude outside the opening of the tank assembly.

11. The wafer pretreatment device as recited in claim 10, wherein a limiting structure is disposed inside the opening, the limiting structure protrudes from an inner side surface of the tank assembly, and the tray can rotate until an end surface of one end of the tray abuts against one side of the limiting structure.