Wafer cleaning device, system and working method of the system

Abstract

The application discloses a wafer cleaning device, a system and a working method of the system, and the device comprises a vacuum chuck, an integrated cleaning execution mechanism is arranged above the vacuum chuck, and a driving mechanism is connected to one end of the cleaning execution mechanism; the cleaning execution mechanism comprises a brush head, the brush head is sleeved on a transmission shaft, at least one cleaning liquid pipeline is arranged in the transmission shaft, a pipeline support shaft is connected to the cleaning liquid pipeline, one end of the cleaning liquid pipeline extends outward along the length direction of the pipeline support shaft, a plurality of liquid outlets are arranged on the other end of the cleaning liquid pipeline, and a plurality of liquid guide holes are arranged on the transmission shaft and the brush head relative to the positions of the liquid outlets. The application has the advantages of compact structure, convenient control and improved wafer brushing efficiency. Through the design of the brush head structure, the liquid pipeline does not rotate with the brush head in the rotating process of the brush head, so that the cleaning liquid does not splash and waste along with the rotating movement of the brush head.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wafer cleaning equipment, and particularly relates to a wafer cleaning device, a system and a method of the system. BACKGROUND

[0002] Cleaning is an important step in the processing of wafer semiconductor products, and directly determines the quality of the wafer surface. The wafer cleaning device mainly includes three parts: one is a vacuum chuck at the bottom, which is used to adsorb the wafer to prevent displacement or sliding of the wafer during the cleaning process; the second is a two-fluid nozzle, which is used to spray cleaning liquid on the wafer surface. The cleaning liquid can be deionized water, diluted hydrofluoric acid and standard cleaning liquid. The cleaning liquid is delivered from the liquid path to the nozzle of the two-fluid nozzle to realize the flushing of the wafer surface; the third is a PVA brush head which brushes the wafer after spraying the cleaning liquid. The wafer is rotated by the vacuum chuck, and the difference in contact force between the convex points of the brush head at different positions and the wafer surface in the radial direction is used to drive the brush head to rotate, so as to achieve the purpose of removing the particles on the wafer surface.

[0003] However, the above-mentioned wafer cleaning device adopts a split design of the two-fluid nozzle and the PVA brush head, and needs to spray cleaning liquid through the two-fluid nozzle and brush the wafer surface through the brush head, so the structure is not simple and the brushing efficiency is not high. SUMMARY

[0004] The purpose of the present application is to provide a wafer cleaning device, a system and a method of the system, to solve the technical problems of the prior art that the two-fluid nozzle sprays cleaning liquid and the brush head brushes the wafer surface, the structure is not simple and the brushing efficiency is not high.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] On the one hand, a wafer cleaning device is provided, which includes a vacuum chuck for adsorbing a wafer on its upper surface, an integrated cleaning execution mechanism is arranged above the vacuum chuck, and a driving mechanism is connected to one end of the cleaning execution mechanism.

[0007] The cleaning execution mechanism includes a brush head arranged above the vacuum chuck, the brush head is sleeved on a transmission shaft, at least one cleaning liquid pipeline is arranged in the transmission shaft, a pipeline support shaft is connected to the cleaning liquid pipeline to fix it in the transmission shaft, one end of the cleaning liquid pipeline extends outward along the length direction of the pipeline support shaft to connect a cleaning liquid storage device, a plurality of liquid outlets are arranged at the position close to the upper side of the vacuum chuck at the other end of the cleaning liquid pipeline, and a plurality of liquid guide holes are arranged at the positions of the transmission shaft and the brush head relative to the liquid outlets, so that the cleaning liquid is sprayed on the wafer surface through the liquid outlets and the liquid guide holes in sequence.

[0008] The driving mechanism comprises a first motor, an output end of the first motor is provided with a transmission shaft, one end of the transmission shaft is connected with the transmission rotating shaft through a steering gear, a ball screw lifting structure is connected on the transmission shaft, and the ball screw lifting structure is driven by a second motor.

[0009] In a possible design, the liquid outlets are provided as liquid outlet columns perpendicular to the wafer surface, and the diameter of the liquid outlet column close to the center of the wafer surface is greater than the diameter of other liquid outlet columns.

[0010] In a possible design, the relative positions of the brush head and the transmission rotating shaft are provided with a plurality of rectangular liquid guide outlets, each of which is provided in one-to-one correspondence with one of the liquid outlets; the relative positions of the brush head and the transmission rotating shaft are provided with a plurality of circular liquid guide holes and a plurality of concave liquid guide grooves, so that the part of the cleaning liquid blocked due to the rotation of the brush head flows out from the circular liquid guide holes through the liquid guide grooves and then drops on the wafer surface.

[0011] In a possible design, a sealing structure is arranged outside the cleaning liquid pipeline, a through hole with a diameter smaller than that of the liquid outlet is arranged on the sealing structure relative to the position of the liquid outlet, a labyrinth flow resistance member is arranged on one side of the sealing structure, and a corrosion-resistant sealing ring is arranged at the end of the sealing structure.

[0012] In a possible design, the output end of the first motor is connected with the transmission shaft through a flexible coupling.

[0013] The second aspect provides a wafer cleaning system, comprising a control terminal, a force sensor, and a wafer cleaning device according to any one of the possible designs of the first aspect, the control terminal is connected with the force sensor, the vacuum chuck, the first motor, and the second motor respectively, and the force sensor is arranged at the bottom of the upper cover of the vacuum chuck.

[0014] The third aspect provides a working method of the wafer cleaning system according to the second aspect, comprising:

[0015] The cleaning liquid is delivered to above the wafer through the cleaning liquid pipeline, so that the cleaning liquid is sprayed on the wafer surface through the liquid outlets of the cleaning liquid pipeline, the liquid guide outlets of the transmission rotating shaft, and the liquid guide holes of the brush head in turn;

[0016] The second motor is controlled by the control terminal to drive the ball screw lifting structure to press down, so as to drive the transmission shaft to drive the transmission rotating shaft to press down to make the brush head contact with the wafer surface, and the first motor is controlled by the control terminal based on a preset rotating speed to drive the transmission shaft, and then drive the transmission rotating shaft to drive the brush head to rotate, so as to realize the brushing of the wafer surface.

[0017] The contact force between the brush head and the wafer surface is detected in real time by the force sensor and uploaded to the control terminal, so that the control terminal monitors whether the contact force between the brush head and the wafer surface is an optimal contact force in real time, and if not, the upper part of the second motor-driven ball screw lifting structure is adjusted by the control terminal to adjust the contact force.

[0018] In a possible design, the preset rotating speed is measured by the following method:

[0019] The contact force between the brush head and the wafer surface is set to a constant value, and the wafer surface is brushed by using the same surface structure and brush heads with different rotating speeds.

[0020] The surface quality of the brushed wafer is compared, and the rotating speed of the brush head corresponding to the optimal surface quality is set as the preset rotating speed of the brush head of the surface structure.

[0021] In a possible design, the optimal contact force is measured by the following method:

[0022] The wafer surface is brushed by using the same surface structure and brush heads with the same rotating speed and different contact forces, to obtain the corresponding relationship between the contact force between the brush head and the wafer surface and the surface quality of the wafer.

[0023] According to the corresponding relationship between the contact force between the brush head and the wafer surface and the surface quality of the wafer, the contact force when the surface quality is optimal is regarded as the optimal contact force.

[0024] In a possible design, the method further comprises:

[0025] The control terminal monitors whether the contact force between the brush head and the wafer surface reaches a limit value in real time, and if so, the upper part of the second motor-driven ball screw lifting structure is controlled to adjust the contact force, wherein the limit value includes an upper limit value and a lower limit value, the upper limit value is the contact force value when the wafer surface is damaged by brushing the wafer surface by the brush head, and the lower limit value is the contact force value when the PVA brush head is completely separated from the wafer surface.

[0026] If the contact force between the brush head and the wafer surface reaches the upper limit value, the second motor-driven ball screw lifting structure is controlled to rise, and if the contact force between the brush head and the wafer surface reaches the lower limit value, the second motor-driven ball screw lifting structure is controlled to descend.

[0027] The beneficial effects of the present application compared with the prior art are:

[0028] 1.The present application sets an integrated cleaning actuator, so that the cleaning liquid nozzle and the brush head are fused, corresponding liquid outlets and liquid guide holes are arranged at the corresponding positions of the cleaning liquid pipeline, the transmission shaft and the brush head in the cleaning actuator, the cleaning liquid is transported to the liquid outlet through siphon effect, and then flows out through the liquid guide hole, so that the whole wafer is fully covered and sprayed under the rotation of the vacuum chuck, and the wafer surface is brushed through the brush head. The whole device structure is more compact, the control is more convenient, and the wafer brushing efficiency is improved. Through the design of the brush head structure, the liquid pipeline does not rotate with the brush head during the rotation of the brush head, so that the cleaning liquid does not splash and waste with the rotation of the brush head.

[0029] 2.The present application sets the liquid outlet as a liquid outlet column perpendicular to the wafer surface, and the pipeline diameter of the liquid outlet column close to the center of the wafer surface is larger than that of other liquid outlet columns, so that under the condition of the same liquid supply pressure and main pipeline diameter, the flow rate of the liquid outlet pipeline close to the center position in unit time is higher, and the larger convex point density on the middle position of the PVA brush head surface can assist the fine particles to separate from the wafer surface, so as to achieve the purpose of higher surface quality.

[0030] 3.The present application sets rectangular liquid guide holes, circular liquid guide holes and recessed flow guide grooves on the transmission shaft and the brush head, so that most of the cleaning liquid flows out from the liquid outlet of the pipeline, and a small part of the cleaning liquid flows out from the circular liquid guide hole through the flow guide groove when the brush head rotates or the cleaning liquid is blocked after spraying, and sprays on the wafer surface, the wafer rotates under the driving of the vacuum chuck, and reaches the effect that the cleaning liquid completely covers the wafer surface under the action of centrifugal force, so as to provide subsequent brush head for comprehensive brushing of the wafer surface.

[0031] 4.The present application is provided with a sealing structure outside the cleaning liquid pipeline, a labyrinth flow resistance member is arranged on one side of the sealing structure, and a corrosion-resistant sealing ring is arranged at the end of the sealing structure, so as to prevent the cleaning liquid from contacting the driving mechanism during spraying and causing corrosion and damage to the mechanism.

[0032] 5.The present application connects the output end of the first motor and the transmission shaft through a flexible coupling, so as to compensate the center line deviation between the output end of the driving motor and the transmission shaft, and at the same time protect the driving motor and prevent the motor from being blocked.

[0033] 6.The application fuses the ball screw lifting structure and the contact force detection feedback, controls the contact force between the brush head and the wafer surface within a reasonable range (the convex points of the brush head are pressed too deep, otherwise the oxide film on the wafer surface will be damaged, and too shallow will result in that the cleaning effect cannot meet the requirements), controls the ball screw lifting structure to automatically stop lifting when the contact force reaches the optimal contact force range, and adjusts the lifting according to the real-time contact force value during the brushing process, so as to ensure that the contact force between the brush head and the wafer surface is maintained at the optimal contact force, and thus the cleaning effect is better. In addition, when the contact force reaches the limit value, the brush head is automatically controlled to stop continuing to press down; when the brush head and the wafer surface are separated (the contact force is 0), the brush head is automatically controlled to stop continuing to rise, so as to realize the automatic control of the contact force within a reasonable range, improve the lifting efficiency and accuracy, and thus improve the surface quality and yield of the wafer after brushing.

[0034] 7.The application sets the contact force between the brush head and the wafer surface as a constant value, uses the same surface structure and different rotating speeds of the brush head to brush the wafer surface, compares the surface quality of the brushed wafer, sets the rotating speed of the brush head corresponding to the optimal surface quality as the preset rotating speed of the brush head of the surface structure, so as to obtain the relative rotating speed required by the brush head to achieve the optimal brushing effect; similarly, the relative rotating speed corresponding to the optimal brushing effect of the brush head of different surface structures can be obtained, as well as the brushing time required to achieve the same and meet the requirements of the cleaning effect, so as to more scientifically judge the advantages and disadvantages of the surface structure of the brush head, which is of great significance for the optimal design of the brush head structure and the full utilization of the cleaning efficiency of the existing brush head. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 It is a structure schematic diagram of the wafer cleaning device in the embodiment of the application;

[0036] Figure 2 It is a structure schematic diagram of the cleaning execution mechanism in the embodiment of the application;

[0037] Figure 3 It is an enlarged schematic diagram of A in the embodiment of the application;

[0038] Figure 4 It is an enlarged schematic diagram of B in the embodiment of the application;

[0039] Figure 5 It is a structure schematic diagram of the brush head in the embodiment of the application;

[0040] Figure 6 It is a structure schematic diagram of the transmission shaft in the embodiment of the application;

[0041] Figure 7 It is another structure schematic diagram of the transmission shaft in the embodiment of the application;

[0042] Figure 8 A schematic structural diagram of a wafer cleaning system in an embodiment of the present application;

[0043] Figure 9 A flow chart of a working method of a wafer cleaning system in an embodiment of the present application.

[0044] Wherein, 1-vacuum chuck; 2-cleaning execution mechanism; 21-brush head; 22-transmission shaft; 23-cleaning liquid pipeline; 24-pipeline support shaft; 25-liquid outlet column; 26-rectangular liquid guide hole; 27-circular liquid guide hole; 28-liquid guide groove; 29-sealing structure; 29A-labyrinth flow resistance member; 29B-sealing ring; 3-driving mechanism; 31-first motor; 32-transmission shaft; 33- steering gear; 34-ball screw lifting structure; 35-second motor; 4-flexible coupling. DETAILED DESCRIPTION

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the present application will be briefly introduced below in combination with the drawings and the description of the embodiments or the prior art. Obviously, the following description of the structures of the drawings is only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor. It should be noted that the description of these embodiment modes is used to help understand the present application, but does not constitute a limitation on the present application.

[0046] Embodiment one

[0047] In order to solve the technical problems of the prior art that the two-fluid nozzle sprays cleaning liquid and the brush head brushes the wafer surface, the structure is not simple enough and the brushing efficiency is not high, and the operation is not convenient. The present application provides a wafer cleaning device, which integrates the cleaning liquid nozzle and the brush head by setting an integrated cleaning execution mechanism, sets corresponding liquid outlets and liquid guide holes in the cleaning execution mechanism, the cleaning liquid pipeline, the transmission shaft and the brush head corresponding positions, transports the cleaning liquid to the liquid outlet through the siphon effect, and flows out through the liquid guide hole, so as to realize full coverage spraying of the entire wafer under the rotation of the vacuum chuck, and realize the brushing of the wafer surface through the brush head. The whole device structure is more compact, the control is more convenient, the brushing efficiency of the wafer is improved, and the liquid pipeline does not rotate with the brush head in the rotation process of the brush head through the design of the brush head structure, so that the cleaning liquid does not splash and waste with the rotation of the brush head.

[0048] The wafer cleaning device provided in the embodiments of the present application will be described in detail.

[0049] As Figures 1-7As shown, in one aspect, a wafer cleaning device is provided, which comprises a vacuum chuck 1 for adsorbing a wafer on its upper surface, preferably, the vacuum chuck 1 is made of polypropylene material, the vacuum chuck 1 can drive the wafer to rotate, and a centrifugal force is generated during rotation, an integrated cleaning execution mechanism 2 is arranged above the vacuum chuck 1, one end of the cleaning execution mechanism 2 is connected with a driving mechanism 3;

[0050] The cleaning execution mechanism 2 comprises a brush head 21 arranged above the vacuum chuck 1, preferably a PVA brush head 21, the brush head 21 is sleeved on a transmission shaft 22, the brush head 21 comprises a body sleeved on the transmission shaft 22 and a plurality of protrusions arranged on the body, the brush head 21 can be a cylindrical brush head 21 or a mushroom head brush head 21, the shape, size, number and position of the protrusions on the body of the brush head 21 can be set according to requirements, which are not limited here; at least one cleaning liquid pipeline 23 is arranged inside the transmission shaft 22, the number of pipelines can be set according to cleaning requirements, which is not limited here, the cleaning liquid pipeline 23 is connected with a pipeline support shaft 24 to realize fixation in the transmission shaft 22, specifically, a plurality of buckles are arranged on the pipeline support shaft 24, preferably, the buckles are annular buckles, the cleaning liquid pipeline 23 is fixed on the pipeline support shaft 24 through the buckles, and then fixed in the transmission shaft 22, one end of the cleaning liquid pipeline 23 extends outward along the length direction of the pipeline support shaft 24 to connect a cleaning liquid storage device, and cleaning liquid is sucked from the cleaning liquid storage device through siphon action, a plurality of liquid outlets are arranged at the other end of the cleaning liquid pipeline 23 close to the position above the vacuum chuck 1, specifically, a plurality of nozzles perpendicular to the surface of the wafer can be arranged at the end of the pipeline; a plurality of liquid guide holes are arranged on the transmission shaft 22 and the brush head 21 relative to the position of the liquid outlets, so that the cleaning liquid is sprayed on the surface of the wafer through the liquid outlets and the liquid guide holes in turn, and the rotation of the vacuum chuck 1 drives the wafer to rotate to generate a centrifugal force, so as to cover the cleaning liquid on the whole surface of the wafer; preferably, the transmission shaft 22, the pipeline support shaft 24 and the brush head 21 are made of a material (such as Teflon) which is corrosion-resistant and has self-lubricating property;

[0051] The driving mechanism 3 comprises a first motor 31, preferably a servo motor, an output end of the first motor 31 is provided with a transmission shaft 32, one end of the transmission shaft 32 is connected with the transmission shaft 22 through a steering gear 33, preferably, the transmission shaft 32 is vertically arranged, the transmission shaft 22 is horizontally arranged, the steering gear 33 is arranged as a pair of bevel gears, the transmission shaft 32 realizes motion transmission in the vertical direction through the pair of bevel gears to drive the transmission shaft 22 to rotate, a ball screw lifting structure 34 is connected on the transmission shaft 32, the ball screw lifting structure 34 is driven by a second motor 35, preferably, the second motor 35 adopts a servo motor.

[0052] Based on the above disclosure, the embodiment of the application sets the integrated cleaning execution mechanism 2, so that the cleaning liquid nozzle and the brush head 21 are fused, corresponding liquid outlets and liquid guide openings are arranged on the cleaning execution mechanism 2, the transmission shaft 22 and the brush head 21 at corresponding positions, the cleaning liquid is delivered to the liquid outlet through siphon action, and flows out through the liquid guide opening, so that the whole wafer is fully covered and sprayed under the rotation of the vacuum chuck 1, and the wafer surface is brushed by the brush head 21. The whole device structure is more compact, the control is more convenient, the wafer brushing efficiency is improved, and through the design of the brush head 21 structure, the liquid delivery pipeline does not rotate with the brush head 21 in the rotation process of the brush head 21, so that the cleaning liquid does not splash and waste with the rotation of the brush head 21.

[0053] In a specific embodiment, the liquid outlet is arranged as a liquid outlet column 25 perpendicular to the wafer surface, and the diameter of the liquid outlet column 25 near the center of the wafer surface is larger than that of other liquid outlet columns 25, so that the liquid pipeline near the center position has a higher flow rate per unit time under the same liquid supply pressure, thereby achieving the purpose of assisting the detachment of fine particles near the center position from the wafer surface even if the centrifugal force of the wafer center is small; in addition, preferably, four liquid outlet columns are arranged on the liquid outlet pipe along the radial direction of the vacuum chuck, the inlet pressures of the four liquid outlet columns decrease from left to right, and in order to meet the requirements of large flow rate of the middle two liquid outlet columns and small flow rate of the two side liquid outlet columns, the cross-sectional size of the liquid outlet column needs to be designed.

[0054] It should be noted that one or two cleaning liquid pipelines need to ensure that the flow rate meets the requirements, that is, the flow rate of the liquid outlet column near the wafer center position is greater than that of the liquid outlet column far from the wafer center position, in the case of one liquid outlet pipe: the pressures of the four liquid outlets from left to right decrease one by one, and the flow rate depends on the diameter of the liquid outlet, so it needs to be set according to requirements; in the case of two liquid outlet pipes: two liquid outlets are arranged on each pipe on the same side, the pressure of the left liquid outlet is greater than that of the right liquid outlet, and whether siphon is feasible or a hydraulic pump is used for pressurization.

[0055] In a specific embodiment, the relative position of the brush head 21 and the transmission shaft 22 is provided with a plurality of rectangular liquid guide openings, each of which is provided one-to-one with one liquid outlet; the relative position of the brush head 21 and the transmission shaft 22 is provided with a plurality of circular liquid guide holes 27 and a plurality of concave flow guide grooves 28, so that the part of the cleaning liquid blocked by the rotation of the brush head flows out from the circular liquid guide hole 27 through the flow guide groove 28 and drops on the wafer surface, so that most of the cleaning liquid flows out from the rectangular liquid guide hole 26 after flowing out from the liquid outlet of the pipeline, and a small part of the cleaning liquid flows out from the circular liquid guide hole 27 through the flow guide groove 28 and sprays on the wafer surface when the brush head rotates or the cleaning liquid is blocked after spraying, the wafer is rotated under the driving of the vacuum chuck, and the centrifugal force achieves the effect that the wafer surface is completely covered with cleaning liquid for subsequent brush head to fully clean the wafer surface.

[0056] In a specific embodiment, the cleaning liquid pipeline 23 is provided with a sealing structure 29 outside, the sealing structure 29 is provided with a through hole with a diameter smaller than that of the liquid outlet relative to the position of the liquid outlet, one side of the sealing structure 29 is provided with a labyrinth flow resistance member 29A, and the end of the sealing structure 29 is provided with a corrosion-resistant sealing ring 29B, so that the cleaning liquid can be prevented from contacting the driving mechanism 2 when spraying to cause corrosion and damage to the mechanism.

[0057] In a specific embodiment, the output end of the first motor 31 is connected with the transmission shaft 32 through a flexible coupling 4, so as to compensate for the center line deviation between the output end of the driving motor and the transmission shaft 32, and at the same time protect the driving motor and prevent the motor from being blocked.

[0058] Embodiment two

[0059] As shown in Figure 8 The second aspect of the embodiment of the application provides a wafer cleaning system, which comprises a control terminal, a force sensor and a wafer cleaning device as described in any one of the possible designs of the first aspect, the force sensor is provided with two, the control terminal is connected with the force sensor, the vacuum chuck 1, the first motor 31 and the second motor 35 respectively, and the force sensor is arranged at the bottom of the upper cover of the vacuum chuck 1; preferably, the control terminal comprises an upper computer and a control card, the control card is inserted into the slot of the control terminal, and the upper computer stores the running program of the wafer cleaning system; the control card is used to obtain the instructions of the running program and is connected to the driver of the motor, the driver is connected to the motor, and the control card realizes closed-loop control of the motor through the serial port.

[0060] It is to be noted that there are three reasons for placing the force sensor under the vacuum chuck 1: firstly, it is more accurate to measure the contact force and its change (compared to placing it at the position of the brush head 21), specifically, if the force sensor is arranged on the brush head 21, the brush head 21 full of cleaning liquid (which is corrosive) will be deformed, which makes it difficult to measure the change of the contact force between the brush head 21 and the wafer, and it is also difficult to judge the surface quality of the wafer after cleaning by the change curve of the contact force, and it is also difficult to explore the influence of the relative rotation speed and surface structure of the brush head 21 on the surface quality of the wafer after cleaning by controlling the contact force. The upper cover of the vacuum chuck 1 has high hardness, and the wafer adsorbed on the vacuum product is hard and brittle, so placing the force sensor under the vacuum chuck 1 can more accurately measure the contact force between the brush head 21 and the wafer surface, which provides a guarantee for the accuracy of the data. Secondly, it avoids damage to the force sensor caused by long-term exposure to a corrosive environment. Thirdly, according to the change of the contact force value in the waveform diagram of the control terminal, the stability of the contact force during cleaning is monitored to determine the effect of cleaning.

[0061] Preferably, the force sensor is a cylindrical force sensor, the bottom of the cylindrical force sensor is connected to the base on the body of the vacuum chuck 1 through a stud, and the top of the force sensor is connected to the upper cover of the vacuum chuck 1 through a connecting cover. Specifically, the top of the cylindrical force sensor is connected to the upper part of the vacuum chuck 1 through a threaded hole on the connecting plate. The force sensor not only realizes the function of measuring the contact force, but also realizes the connection between the upper structure of the vacuum chuck 1 and the support plate at the bottom of the vacuum chuck 1. The rigidity of the cylindrical force sensor can fully meet the actual requirements.

[0062] Based on the above disclosure, the embodiment of the present application provides a hardware architecture of a wafer cleaning system. Through the cooperation of the hardware architecture and the subsequent software method, the linkage control of the wafer cleaning process can be realized.

[0063] Embodiment three

[0064] As shown in Figure 9 The third aspect of the embodiment of the present application provides a working method of the wafer cleaning system according to the second aspect, which includes but is not limited to the steps S1-S3:

[0065] Step S1. Deliver the cleaning liquid to the upper part of the wafer through the cleaning liquid pipeline 23, so that the cleaning liquid is sprayed on the wafer surface through the liquid outlet of the cleaning liquid pipeline 23, the liquid guide hole of the transmission shaft 22 and the liquid guide hole of the brush head 21 in turn;

[0066] When using a traditional cleaning fluid nozzle to spray the wafer surface, if the pressure of the cleaning fluid sprayed by the nozzle is too low, the cleaning fluid will not be able to cover the entire wafer surface; while if the pressure is too high, it will cause damage defects on the wafer surface, thereby directly reducing the wafer yield. Therefore, the cleaning fluid should cover the wafer surface rather than achieve the purpose of cleaning by pressure rinsing. In this embodiment, the cleaning fluid is input from an external cleaning fluid storage device through a pipeline and finally flows out from the nozzle at a reserved position on the brush head 21. Through siphon action, the cleaning fluid flows down the pipeline from the cleaning fluid storage device and finally drips onto the wafer surface. The vacuum suction cup 1 drives the wafer to rotate, and under the action of centrifugal force, the entire wafer surface can be covered, avoiding surface defects caused by pressure rinsing. At the same time, as the cleaning fluid flows from the position near the center of the wafer to the edge, it also carries away the particles attached to the protrusions of the brush head 21, thereby cleaning the brush head 21. Corresponding liquid outlet structures are also designed at the corresponding positions of the cleaning fluid pipeline 23, the rotating shaft, and the brush head 21 to facilitate the flow of cleaning fluid, improve the cleaning effect of the entire cleaning system, and make the overall size more compact and reasonable.

[0067] Specifically, most of the cleaning fluid flows out from the outlet of the pipeline and mainly flows out from the rectangular guide hole 26. Due to the rotation of the brush head 21, some of the cleaning fluid is blocked. The blocked cleaning fluid flows out from the circular guide hole 27 under the guidance of the guide groove 28 and sprays onto the wafer surface, thereby avoiding the waste of cleaning fluid and achieving the effect of wetting and cleaning the PVA brush.

[0068] Step S2. The control terminal controls the second motor 35 to drive the ball screw lifting structure 34 to press down, thereby driving the transmission shaft 32 to drive the transmission shaft 22 to press down so that the brush head 21 contacts the wafer surface. The control terminal controls the first motor 31 to drive the transmission shaft 32 based on the preset speed, thereby driving the transmission shaft 22 to drive the brush head 21 to rotate, so as to realize the wafer surface cleaning.

[0069] It should be noted that the host computer of the control terminal stores the system's operating program, such as a LabVIEW-style program. The control card acquires the preset operating speed of the brush head 21 from the program, and may also include parameters such as acceleration time, deceleration time, rotation direction, and number of rotations. These parameters are then transmitted to the first motor 31 via the control card. Preferably, the first motor 31 is equipped with a CN1 signal port for data reception. The control card then drives the servo motor using a pulse-plus-direction control method. Specifically, a speed signal, which is a preset optimal speed, is input into the control panel. The control card controls the motor, while a photoelectric encoder collects the motor's speed and direction signals and feeds them back to the host computer. The program in the host computer obtains the speed difference between the actual speed and the theoretical control speed, and then uses a PID program to adjust the speed, forming a closed loop.

[0070] The PID parameters of the servo motor are set by the debugging software in the host computer, so that better dynamic response speed can be achieved. The PID adjustment process is as follows: KP represents the proportional relationship between the current acceleration torque and the error (the current speed and the required speed). The larger the KP is, the faster the response speed of the system is, but the more serious the oscillation when the system reaches the target speed is. In order to reduce the oscillation of the system, Kd is used to solve the problem. The error is the difference of the speed, and the differentiation of the speed is the acceleration of the speed. When KP is large, Kd can offset part of the acceleration generated by KP, so as to realize the control of the acceleration and reduce the oscillation of the system. The KI parameter is used to eliminate the error between the actual speed and the target speed. KI accumulates the error to provide acceleration until the error is eliminated, i.e. the target speed is reached.

[0071] In step S2, the preset speed is measured by the following method in one specific embodiment:

[0072] (1) The contact force between the brush head 21 and the wafer surface is set to a constant value, and the wafer surface is brushed by using the same surface structure and different speeds of the brush head 21.

[0073] (2) The surface quality of the brushed wafer is compared, and the speed of the brush head 21 corresponding to the optimal surface quality is set as the preset speed of the brush head 21 of the surface structure.

[0074] Similarly, it can be understood that based on the principle of the above method, the optimal value of the contact force between the brush head 21 and the wafer surface can be obtained, which is as follows:

[0075] The speed of the brush head 21 is kept constant, and the relationship between the contact force between the brush head 21 and the wafer surface and the surface quality of the brushed wafer is obtained. Through multiple tests, the optimal contact force range of the same type of brush head 21 and the wafer surface can be obtained, which improves the surface quality of the brushed wafer and reduces the probability of damage to the oxide film on the wafer surface, thereby improving the yield of the wafer. Moreover, there is a more reasonable and scientific basis for evaluating the brushing effect of the brush head 21 (the optimal brushing speed and contact force of the PVA brush head with different surface structures can be measured by this device, thereby eliminating the influence of different optimal relative speeds of the brush head 21 with different convex point arrangements and shapes), the optimal speed of the P brush head 21 in the brushing process and the brushing time required to achieve the same cleaning effect are obtained through experiments, and the scientific and reasonable comparison of the cleaning effect of the brush head 21 with different convex point shapes and arrangement structures is realized.

[0076] Step S3. Real-time detection of the contact force between the brush head 21 and the wafer surface by the force sensor and uploading to the control terminal, so that the control terminal monitors whether the contact force between the brush head 21 and the wafer surface is the optimal contact force in real time, and if not, the control terminal controls the second motor 35 to drive the upper part of the ball screw lifting structure 34 to adjust the contact force.

[0077] In a possible design, the optimal contact force is measured by the following method:

[0078] The wafer surface is brushed with different contact forces than the crystal surface by the same surface structure and the same rotating speed of the brush head 21, and the corresponding relationship between the contact force between the brush head 21 and the wafer surface and the surface quality of the wafer is obtained.

[0079] According to the corresponding relationship between the contact force between the brush head 21 and the wafer surface and the surface quality of the wafer, the contact force when the surface quality is optimal is regarded as the optimal contact force.

[0080] In a possible design, the method further comprises:

[0081] The control terminal monitors whether the contact force between the brush head 21 and the wafer surface reaches the limit value in real time, and if so, controls the second motor 35 to drive the upper part of the ball screw lifting structure 34 to adjust the contact force, wherein the limit value includes an upper limit value and a lower limit value, the upper limit value is the contact force value when the surface oxide film is damaged by brushing the wafer surface with the brush head, and the lower limit value is the contact force value when the PVA brush head is completely separated from the wafer surface, and preferably, the lower limit value is 0.

[0082] If the contact force between the brush head 21 and the wafer surface reaches the upper limit value, the second motor 35 is controlled to drive the ball screw lifting structure 34 to rise, and if the contact force between the brush head 21 and the wafer surface reaches the lower limit value, the second motor 35 is controlled to drive the ball screw lifting structure 34 to descend.

[0083] It is to be noted that the contact force between the brush head 21 and the wafer surface is controlled within a reasonable range by fusing the ball screw lifting structure 34 and the contact force detection feedback. If the convex points of the brush head are pressed too deeply, the oxide film on the wafer surface will be damaged, and if the convex points are too shallow, the cleaning effect will not meet the requirements. When the contact force reaches the optimal contact force range, the ball screw lifting structure 34 is automatically stopped from lifting and descending, and the lifting is adjusted according to the real-time contact force value during the brushing process, so as to maintain the contact force between the brush head 21 and the wafer surface at the optimal contact force, thereby achieving better cleaning effect. In addition, when the contact force reaches the limit value, the brush head 21 is automatically controlled to stop further pressing; when the brush head 1 and the wafer surface are separated (the contact force is 0), the brush head 21 is automatically controlled to stop further rising, thereby realizing automatic control of the contact force within a reasonable range, improving the lifting efficiency and accuracy, and thus improving the surface quality and yield of the wafer after brushing.

[0084] In a specific embodiment, preferably, when the first motor 31 is a servo motor, the first motor is provided with an optical encoder. The code disc of the optical encoder outputs two phases of light code with a phase difference of 90 degrees. According to the change of the state of the double-channel output light code, the rotation direction of the first motor 31 can be judged, and the rotation speed and direction data of the brush head 21 can be collected through the optical encoder. When the first motor 31 is not a servo motor, for example, a stepper motor, a grating disc can be coaxially arranged with the first motor 31, so that the rotation of the first motor 31 drives the rotation of the grating disc. Then, a plurality of pulse signals are outputted through the photoelectric detection device. According to the number of pulses per second, the current rotation speed of the first motor 31 can be obtained. The speed data is fed back to the monitoring control system of the upper computer in real time through the LABVIEW program of the upper computer, a control card, and then a driver of the first motor 31, and the response rate of the system is improved through the cascade control strategy. At the same time, the contact force measurement data is combined with the lifting of the motor-driven ball screw to drive the lifting of the overall structure of the brush head 21. The contact force is indirectly controlled by adjusting the pressing depth of the convex points of the brush head 21 relative to the wafer surface. The contact force curve during the brushing process is obtained through the contact force measurement program. According to the stability of the curve, the brushing effect is judged to ensure the yield and surface quality of the wafer after brushing.

[0085] Based on the above disclosure, the embodiment of the application fuses the ball screw lifting structure 34 and the contact force detection feedback, controls the contact force between the brush head 21 and the wafer surface within a reasonable range (the convex points of the brush head 21 are pressed too deep, otherwise the oxide film on the wafer surface will be damaged, and too shallow will result in that the cleaning effect cannot meet the requirements), when the contact force reaches the limit value, the automatic control stops the brush head 21 from continuing to press down; when the brush head 21 and the wafer surface are separated (the contact force is 0), the automatic control stops the brush head 21 from continuing to rise, so as to realize the automatic control of the contact force within a reasonable range, improve the efficiency and accuracy of lifting, and improve the surface quality and yield of the wafer after brushing. By setting the contact force between the brush head 21 and the wafer surface as a constant value, the same surface structure and different rotating speeds of the brush head 21 are used to brush the wafer surface; the surface quality of the brushed wafer is compared, the corresponding brush head 21 rotating speed when the surface quality is optimal is set as the preset rotating speed of the brush head 21 of the surface structure, so as to obtain the relative rotating speed required by the brush head 21 of the type to achieve the best brushing effect; similarly, the relative rotating speed corresponding to the brush head 21 of different surface structures to achieve the best brushing effect can be obtained, and the brushing time required to achieve the same and meet the requirements of the cleaning effect, so as to more scientifically judge the advantages and disadvantages of the surface structure of the brush head 21, and the optimization design of the brush head 21 structure and the full use of the cleaning efficiency of the existing brush head 21 are of great significance.

[0086] Finally, it should be noted that: the above only describes the preferred embodiments of the application and is not used to limit the protection scope of the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A wafer cleaning apparatus, characterized by comprising: The vacuum chuck (1) is provided with a one-piece cleaning execution mechanism (2) above the wafer, and one end of the cleaning execution mechanism (2) is connected with a driving mechanism (3); The cleaning execution mechanism (2) comprises a brush head (21) provided above the vacuum chuck (1), the brush head (21) is sleeved on a transmission shaft (22), at least one cleaning liquid pipeline (23) is arranged in the transmission shaft (22), the cleaning liquid pipeline (23) is connected with a pipeline support shaft (24) to fix in the transmission shaft (22), one end of the cleaning liquid pipeline (23) extends outward along the length direction of the pipeline support shaft (24) to connect with a cleaning liquid storage device, and the other end of the cleaning liquid pipeline (23) is provided with a plurality of liquid outlets near the position above the vacuum chuck (1); a plurality of liquid guide holes are arranged on the transmission shaft (22) and the brush head (21) relative to the position of the liquid outlet, so that the cleaning liquid is sprayed on the wafer surface through the liquid outlet and the liquid guide hole in sequence; The driving mechanism (3) comprises a first motor (31), the output end of the first motor (31) is provided with a transmission shaft (32), one end of the transmission shaft (32) is connected with the transmission shaft (22) through a steering gear (33), and a ball screw lifting structure (34) is sleeved on the transmission shaft (32); the ball screw lifting structure (34) is driven by a second motor (35); The liquid outlet is provided as a liquid outlet column (25) perpendicular to the wafer surface, and the diameter of the liquid outlet column (25) near the center of the wafer surface is larger than that of other liquid outlet columns (25); The relative positions of the brush head (21) and the transmission shaft (22) are provided with a plurality of rectangular liquid guide holes, and each rectangular liquid guide hole is provided in one-to-one correspondence with one liquid outlet; the relative positions of the brush head (21) and the transmission shaft (22) are provided with a plurality of circular liquid guide holes (27) and a plurality of concave flow guide grooves (28), so that the cleaning liquid is guided out from the circular liquid guide hole (27) through the flow guide groove (28); The outer side of the cleaning liquid pipeline (23) is provided with a sealing structure (29), the sealing structure (29) is provided with a through hole with a diameter smaller than that of the liquid outlet at the position relative to the liquid outlet, one side of the sealing structure (29) is provided with a labyrinth flow resistance part (29A), and the end of the sealing structure (29) is provided with a corrosion-resistant sealing ring (29B); The output end of the first motor (31) is connected with the transmission shaft (32) through a flexible coupling (4).

2. A wafer cleaning system, characterized by, The wafer cleaning device comprises a control terminal, a force sensor and the wafer cleaning device of claim 1, the control terminal is connected with the force sensor, the vacuum chuck (1), the first motor (31) and the second motor (35) respectively, and the force sensor is arranged at the bottom of the upper cover of the vacuum chuck (1).

3. A method of operating a wafer cleaning system as claimed in claim 2, wherein, The wafer cleaning device comprises The cleaning liquid is delivered to the upper side of the wafer through the cleaning liquid pipeline (23) so as to be sprayed on the wafer surface through the liquid outlet of the cleaning liquid pipeline (23), the liquid guide hole of the transmission shaft (22) and the liquid guide hole of the brush head (21) in sequence; The control terminal controls the second motor (35) to drive the ball screw lifting structure (34) to press down, so as to drive the transmission shaft (32) to drive the transmission shaft (22) to press down to make the brush head (21) contact with the wafer surface, and the control terminal controls the first motor (31) to drive the transmission shaft (32) based on the preset rotating speed, so as to drive the transmission shaft (22) to drive the brush head (21) to rotate, thereby realizing the brushing of the wafer surface. The force sensor detects the contact force between the brush head (21) and the wafer surface in real time and uploads it to the control terminal, so that the control terminal can monitor whether the contact force between the brush head (21) and the wafer surface reaches the limit value in real time, and if so, the second motor (35) drives the ball screw lifting structure (34) to adjust the lifting.

4. The method of working according to claim 3, characterized in that, The preset rotating speed is measured by the following method: The contact force between the brush head (21) and the wafer surface is set as a constant value, and the same surface structure and different rotating speeds of the brush head (21) are used to brush the wafer surface. The surface quality of the brushed wafer is compared, and the rotating speed of the brush head (21) corresponding to the optimal surface quality is set as the preset rotating speed of the brush head (21) of this surface structure.

5. The method of working according to claim 3, characterized in that, The limit value of the contact force between the brush head (21) and the wafer surface is measured as follows: The same surface structure and the same rotating speed of the brush head (21) are used to brush the wafer surface with different contact forces, and the corresponding relationship between the contact force between the brush head (21) and the wafer surface and the surface quality of the wafer is obtained. When the brush head (21) contacts the wafer surface with a certain contact force and brushes the wafer surface, the oxide film on the wafer surface is damaged, and the contact force is considered as the upper limit value of the contact force between the brush head (21) and the wafer surface.

6. The method of working according to claim 5, characterized in that, The control terminal monitors whether the contact force between the brush head (21) and the wafer surface reaches the limit value in real time, and if so, the second motor (35) drives the ball screw lifting structure (34) to adjust the lifting, including: The control terminal monitors whether the contact force between the brush head (21) and the wafer surface reaches the upper limit value in real time, and if so, the second motor (35) drives the ball screw lifting structure (34) to rise; The control terminal monitors whether the contact force between the brush head (21) and the wafer surface reaches the lower limit value in real time, and if so, the second motor (35) drives the ball screw lifting structure (34) to descend, wherein the lower limit value is set to 0.

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