Wafer automatic film pasting method

Abstract

This invention discloses an automated wafer bonding method, belonging to the field of semiconductor manufacturing technology. This method uses tension-free adhesive bonding as its core process, achieving fully automated wafer transfer through a mechanical transport mechanism, avoiding direct contact between the wafer and the human body throughout the process. A machine vision recognition system is employed to achieve high-precision alignment between the wafer and the adhesive film, providing a precise positional reference for tension-free bonding. Through its core tension-free bonding design, this invention eliminates the problems of uneven tension and residual internal stress during the adhesive film bonding process, significantly reducing the risk of high warpage in subsequent grinding and etching processes, effectively reducing the breakage rate of thin wafers, and greatly improving the consistency, cleanliness, and operational efficiency of the bonding process, thereby enhancing the overall operational efficiency and market competitiveness of semiconductor production lines.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to an automated wafer lamination method. Background Technology

[0002] In semiconductor manufacturing, the wafer, as the core substrate for chip production, has surface circuit structures with precision down to the micrometer or even nanometer level. Subsequent critical processes such as grinding, thinning, etching, and dicing place extremely stringent requirements on the wafer's surface cleanliness, flatness, and edge integrity. Wafer lamination is a core pre-processing step in semiconductor packaging, testing, and front-end wafer manufacturing. Its core function is to attach a protective film to the wafer surface (usually the front side). This film protects the delicate circuit structures on the front side of the wafer from particle contamination, physical scratches, and chemical corrosion in subsequent processes. Furthermore, the film reinforces the wafer edges, disperses stress concentration during processing, and prevents edge chipping and cracking during grinding, thinning, and dicing. It also provides a stable positioning reference for subsequent processes. Therefore, the quality of the lamination process directly determines the yield of subsequent wafer processes and is one of the core factors affecting semiconductor product manufacturing efficiency and costs.

[0003] Currently, traditional fully automated wafer laminating machines are widely used in semiconductor industry mass production lines to complete the lamination process. The standard process flow is as follows: First, a vacuum suction robotic arm removes the wafer to be laminated from the wafer foyer (FOUP) and transports it to the edge-finding station to complete the wafer centering and circumferential positioning. Then, the adhesive film roll is unwound by a traction mechanism, and the positioned wafer is transported to the lamination and pressing station. After the vacuum suction stage fixes the wafer, it rises to the working height, and the pressing roller rolls from one end of the wafer to the other at a uniform speed, tightly bonding the unwound protective adhesive film to the wafer surface, while eliminating air bubbles at the bonding interface and ensuring no wrinkles. After pressing, a rotary cutting mechanism performs a circular cut along the wafer edge to remove excess adhesive film from the outer perimeter. Finally, a robotic arm transports the laminated wafer to the finished product box, completing the entire lamination process.

[0004] However, the process design of the aforementioned traditional fully automatic film laminating machines has insurmountable core technical defects. The most prominent of these, which has the greatest impact on wafer yield, is the inherent inadequacy of adhesive film tension control. This severely restricts the improvement of semiconductor manufacturing yield and the stability of large-scale mass production. The specific defects are as follows: 1. Uncontrollable film tension leads to high wafer warpage and breakage rates: Traditional fully automatic laminating machines generally employ a "traction unwinding-rolling pressing" process. During film unwinding, a traction mechanism must continuously apply tension to ensure flat film transport, inevitably creating pre-tension within the film. Simultaneously, the unwinding speed of the traction mechanism and the pressing roller's lamination speed cannot achieve real-time, precise closed-loop matching, resulting in large tension fluctuations during lamination. This leads to severe residual internal stress after the film and wafer are bonded. In subsequent wafer grinding and thinning processes, as wafer thickness and rigidity decrease, the residual internal stress within the film is released unevenly, directly causing severe wafer warpage. Industry data shows that when wafers processed using traditional lamination techniques are ground and thinned to below 100μm, the warpage generally exceeds 0.08mm, and the breakage rate of thin wafers is as high as 5%, becoming a core bottleneck restricting ultra-thin wafer manufacturing.

[0005] 2. High risk of contamination, impacting chip yield: While traditional film-coating equipment achieves automated transfer, some stations still require manual intervention and adjustment. Furthermore, insufficient cleanliness control within the equipment cavity allows for particle shedding and airflow disturbances during manual operation, directly leading to wafer surface contamination. Simultaneously, static electricity is easily generated during the film traction process in traditional methods, attracting suspended particles from the environment and further exacerbating the risk of wafer surface contamination. This type of contamination can cause pad contamination and circuit scratches in subsequent photolithography and etching processes, resulting in chip malfunction. Industry statistics indicate that contamination issues caused by traditional film-coating processes account for over 12% of the defect rate in subsequent wafer processes.

[0006] 3. Insufficient alignment accuracy and ineffective edge protection: Traditional fully automatic laminating machines mostly use mechanical structures for positioning, only achieving rough wafer positioning through edge-finding mechanisms. They do not perform high-precision visual alignment of the adhesive film and wafer bonding position, resulting in alignment errors generally exceeding ±0.1mm. This alignment deviation leads to incomplete protection and coverage of the wafer edges by the adhesive film, leaving some edge areas exposed. During subsequent grinding and thinning processes, these areas are prone to stress concentration, causing edge chipping and cracking. Furthermore, adhesive film misalignment may also cover critical positioning marks on the wafer surface, affecting the positioning accuracy of subsequent processes.

[0007] 4. Poor process consistency and drastic yield fluctuations: In traditional film lamination processes, key process parameters such as adhesive film tension, pressure and speed of the pressing rollers, and cutting parameters cannot be precisely controlled in a closed-loop manner throughout the entire process. Speed ​​fluctuations and pressure drifts during equipment operation can lead to significant differences in the film lamination quality between different batches and different wafers. Industry data shows that the coefficient of variation of adhesive film bonding strength in traditional film lamination processes is as high as 15%, directly causing yield fluctuations in subsequent processes to exceed 10%, seriously affecting the stability and repeatability of semiconductor product quality.

[0008] 5. Low matching of work efficiency, restricting mass production capacity: There is redundancy in the process connection of traditional fully automatic film laminating machines. The film lamination cycle of a single wafer is about 2 minutes, and only about 30 wafers can be laminated per hour. As the semiconductor industry develops towards 12-inch wafers and large-scale mass production, the demand for chip production capacity continues to increase. The work efficiency of traditional film laminating equipment can no longer match the work rhythm of subsequent grinding, cutting and other equipment, becoming a bottleneck for the production capacity of semiconductor production lines, resulting in low overall production line operating efficiency.

[0009] In addition, although the few existing improved film lamination equipment have optimized the automation process, they have not been specifically designed for tension control during the film lamination process. They still use the traditional "traction-pressing" process mode, and the problems of film tension fluctuation and internal stress residue have not been fundamentally solved. The improvement effect on wafer warpage is extremely limited and cannot meet the stringent requirements of advanced process wafers for film lamination.

[0010] Therefore, developing an automated wafer bonding method that uses tension-free adhesive bonding as its core and can fundamentally solve problems such as uneven adhesive film tension, wafer warpage, contamination, and insufficient alignment accuracy has become an urgent need for the semiconductor manufacturing industry. Summary of the Invention

[0011] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide an automatic wafer lamination method.

[0012] One of the objectives of this invention is achieved through the following technical solution: An automated wafer bonding method, with tension-free adhesive bonding as the core process, includes the following steps: (1) Automatic wafer loading: The wafer to be coated is transferred to the vacuum adsorption stage of the coating station by a mechanical transfer mechanism to complete the positioning and fixing. The entire transfer process is free from direct contact between the human body and the wafer. (2) Visual alignment: A machine vision recognition system is used to collect the notch or flat edge features of the wafer and the positioning reference features of the adhesive film. Based on the preset alignment algorithm, the wafer and the adhesive film are aligned with high precision, providing a precise position reference for tension-free adhesive application. (3) Tensionless adhesive film bonding: control the adhesive film output speed of the adhesive film release mechanism to match the moving speed of the adhesive film bonding execution mechanism in real time in a closed loop, so as to ensure that no additional tensile tension is generated during the process of covering the wafer surface, and realize tensionless floating bonding between the adhesive film and the wafer surface. (4) Programmed pressing: By pre-setting constant pressing parameters, the pressing rollers perform unidirectional uniform pressing on the adhesive film and wafer that have completed tensionless bonding, solidify the bonding effect and eliminate residual stress. The pressing parameters include roller pressure and roller movement speed. (5) Excess adhesive film cutting: The excess adhesive film is cut synchronously and precisely along the edge contour of the wafer using a ring cutting mechanism to avoid damaging the stable interface formed by tensionless bonding during the cutting process; (6) Automatic unloading of finished products: The wafers after film application are transferred from the film application station to the finished product storage area through a mechanical transmission mechanism to complete the entire film application process; By using the core tension-free bonding design in step (3) and the programmed pressing control in step (4), the problem of uneven tension and residual internal stress in the adhesive film bonding process is completely eliminated, thereby improving the warping and deformation phenomenon in the subsequent grinding and etching processes of the wafer from the root and reducing the breakage rate of thin wafers.

[0013] Furthermore, in step (1), the mechanical transmission mechanism is a vacuum adsorption robotic arm, and the entire process of transfer and film application is carried out in a Class 100 or higher cleanroom environment. The adsorption pressure of the vacuum adsorption robotic arm is -90KPa to -75KPa, which avoids particle contamination or physical damage to the wafer surface and provides a clean and stable working basis for tension-free bonding.

[0014] Further, in step (2), the machine vision recognition system includes a ring light source module and an image processing unit. The alignment accuracy error between the wafer and the adhesive film is ≤ ±0.01mm. The image processing unit identifies the notch or flat edge features of the wafer through a template matching algorithm and identifies the positioning reference features of the adhesive film through an edge detection algorithm, ensuring that the coverage area of ​​the adhesive film and the wafer is accurately matched during the tension-free bonding process, without edge offset.

[0015] Furthermore, in step (3), the real-time difference between the adhesive film output speed of the adhesive film release mechanism and the moving speed of the adhesive film bonding actuator is ≤5mm / s; the moving path of the adhesive film bonding actuator is kept absolutely parallel to the wafer surface, and the moving height error is ≤±5um, ensuring that the adhesive film is not stretched locally or prematurely contacted during the bonding process, thus achieving tension-free bonding throughout the process.

[0016] Further, in step (4), the preset range of the roller pressure is 0.1-0.5MPa, the preset range of the roller movement speed is 10-100mm / s, and the surface hardness of the pressing roller is Shore A60-80 degrees; the pressing process adopts a unidirectional uniform speed pressing method, that is, the pressing roller moves from one end of the wafer to the other end at a uniform speed to ensure that the pressing force is uniformly transmitted to the bonding interface between the adhesive film and the wafer, without destroying the stress balance formed by tensionless bonding.

[0017] Furthermore, in step (5), the gap between the blade of the annular cutting mechanism and the edge of the wafer is ≤0.2mm, the cutting line speed is completely synchronized with the rotational line speed of the wafer, and the cutting speed range is 5-30mm / s, so as to avoid film stretching, stress release or wafer edge chipping during the cutting process, and ensure the interface stability after tension-free bonding.

[0018] Furthermore, in step (3), both the adhesive film release mechanism and the adhesive film bonding execution mechanism are driven by servo motors. The speed is controlled by a PLC control system to achieve real-time closed-loop feedback and dynamic adjustment. The response frequency is ≥100Hz, ensuring stable speed matching accuracy throughout the bonding process without tension fluctuations.

[0019] Furthermore, the execution parameters for all steps are stored in the process database module of the control system. The process database module supports custom editing and one-click recall of parameters. It can quickly match the corresponding tension-free bonding parameters, pressing parameters, and cutting parameters according to the film bonding requirements of wafers of different sizes from 6 to 12 inches, ensuring the consistency of tension-free film bonding effect for wafers of different sizes.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention overturns the traditional "traction-pressing" bonding process, using tension-free adhesive bonding as its core innovation. Through real-time closed-loop speed matching between the adhesive release mechanism and the bonding execution mechanism, it ensures that the adhesive film is free from any external traction or tension force throughout the bonding process, naturally covering the wafer surface solely based on its own flatness. This completely eliminates tension fluctuations and residual internal stress during the adhesive film bonding process. Actual mass production verification shows that 8-inch wafers bonded using this invention, after grinding and thinning to below 100μm, exhibit a maximum warpage ≤0.03mm and an average warpage of only 0.015mm. Compared to traditional bonding processes, this represents an 81.25% improvement in warpage, and reduces the wafer breakage rate to below 0.1%, completely breaking through the technological bottleneck of ultra-thin wafer manufacturing.

[0021] 2. This invention integrates the entire wafer lamination process into a Class 100 or higher-level sealed ultra-clean chamber, using a vacuum-adsorption robotic arm to achieve fully automated wafer loading, unloading, and transfer. The entire process is completely automated, eliminating human contact and intervention, thus cutting off the transmission path of contaminants such as particles and grease introduced by manual operation at the source. Furthermore, the tension-free lamination process eliminates the risk of electrostatic adsorption of particles, preventing contamination. Actual testing shows that wafers laminated using this invention have ≤3 particles larger than 0.5μm per wafer, reducing the contamination rate to below 0.5%. Compared to traditional lamination processes, this represents a 96% improvement in contamination control, effectively preventing chip malfunctions caused by contamination and significantly improving overall product yield.

[0022] 3. This invention employs a machine vision alignment system composed of a ring-shaped LED light source and a dedicated image processing algorithm. This system can accurately identify the notch / flat edge features of the wafer and the positioning reference of the adhesive film, with an alignment accuracy error of ≤±0.01mm. Compared to traditional mechanical positioning laminating equipment, the alignment accuracy is improved by more than 90%. This high-precision alignment ensures a complete match between the adhesive film and the wafer's coverage area during tension-free lamination, eliminating blind spots in wafer edge protection. After mass production verification on 1000 wafers, the wafer edge chipping rate after lamination is 0, effectively guaranteeing the structural integrity of the wafer.

[0023] 4. All core process parameters of this invention, including speed matching parameters for tension-free bonding, pressing parameters, cutting parameters, and adsorption parameters, are uniformly stored, controlled in a closed loop, and executed by the PLC control system. This supports precise one-click recall and custom editing of parameters, ensuring that the film bonding process for each wafer is completely replicated, unaffected by equipment fluctuations or human factors. Testing showed that 100 wafers processed using this invention exhibited a film bonding strength variation coefficient of ≤3%, far lower than the 15% variation coefficient of traditional film bonding processes, improving process consistency by 80%. The yield fluctuation range of subsequent processes was reduced from over 10% to within 3%, providing a stable and reliable process guarantee for the large-scale mass production of semiconductor products.

[0024] 5. This invention, through its fully automated design, eliminates redundant processes in traditional equipment, achieving seamless integration of the entire process from loading, alignment, tension-free bonding, pressing, cutting, and unloading. The film-coating cycle for a single wafer is shortened to less than 1 minute, and 60 wafers can be coated per hour. Compared to traditional fully automated film-coating equipment, the operating efficiency is increased by more than 100%. It is highly compatible with the operating rhythm of subsequent automated equipment such as grinding and cutting, effectively breaking through the capacity bottleneck of semiconductor production lines, significantly reducing the production time cost per wafer, and improving the overall operating efficiency of the production line.

[0025] 6. This invention supports the film application requirements of wafers of all sizes from 6 to 12 inches. By simply adjusting parameters such as adsorption pressure, alignment template, tension-free bonding speed, pressing parameters, and cutting radius through the process database of the control system, the process switching of wafers of different sizes can be quickly completed. It can be widely used in the wafer manufacturing process of various semiconductor products such as logic chips, memory chips, power semiconductors, and third-generation semiconductors. It is compatible with wafers and protective films of different manufacturers and models, and has strong versatility and industry promotion value.

[0026] 7. On the one hand, this invention significantly reduces the scrap losses caused by wafer warpage, chipping, and contamination through its core tension-free bonding design. Based on an annual production of 100,000 8-inch wafers, this can reduce defective product losses by more than 5 million yuan. On the other hand, the fully automated and unmanned operation can reduce the number of film-applying operators by 80%, significantly reducing labor costs. At the same time, the efficient and stable production process reduces equipment idleness and capacity waste, further reducing the overall production cost per unit product and creating significant economic benefits for semiconductor manufacturing companies.

[0027] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0028] Figure 1 This is a flowchart of this embodiment. Detailed Implementation

[0029] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0030] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] This embodiment discloses an automated wafer bonding method based on tension-free adhesive bonding. It is designed for the back protective film bonding process of 8-inch silicon-based wafers in semiconductor mass production lines. Through the core tension-free bonding design, it solves the core problems of wafer warping and breakage caused by uneven adhesive film tension in traditional bonding processes. At the same time, it realizes fully automated, high-cleanliness, and high-precision bonding operations.

[0033] The system configuration used in this embodiment is as follows: Ultra-clean environment system: It adopts a Class 100 sealed ultra-clean chamber, which is equipped with two-stage high-efficiency HEPA filters to meet the ISO14644-1 Class 1 cleanliness standard. The number of suspended particles ≥0.5μm per cubic foot of air does not exceed 100. The ambient temperature in the chamber is controlled at 22±2℃ and the relative humidity is controlled at 45±5%RH to avoid the adverse effects of dust particles and temperature and humidity fluctuations on the wafer surface and tensionless bonding process.

[0034] Mechanical transfer mechanism: A vacuum adsorption robotic arm is selected, and the adsorption surface adopts a ring adsorption design adapted to 8-inch wafers. The adsorption pressure is adjustable from -90KPa to -75KPa. In this embodiment, it is set to -80KPa to ensure uniform force during wafer adsorption and no indentation. The repeatability of the robotic arm is ±0.02mm, which can realize fully automated transfer of wafers from the feeding box to the lamination station and from the lamination station to the finished product storage box, without human contact throughout the process.

[0035] Machine vision alignment system: It consists of a ring-shaped shadowless LED light source, a 5-megapixel industrial camera and an image processing unit. The image processing unit identifies the V-shaped notch of the wafer (notch angle 45°, depth 0.5mm) through a template matching algorithm and identifies the transparent circular positioning mark (diameter 0.3mm) of the adhesive film through a sub-pixel edge detection algorithm. The alignment accuracy error is ≤±0.008mm, providing a precise position reference for tension-free bonding.

[0036] Tension-free adhesive film bonding mechanism: includes adhesive film roll, servo-driven adhesive film release motor, and bonding execution module; the adhesive film is a UV-curable wafer back protective film (model: Lintec T-4000), with a thickness of 80μm and an adhesion of 0.15N / 25mm; the adhesive film release motor adopts high-precision servo control with a speed range of 0.5-5m / min, which can accurately control the adhesive film output speed; the bonding execution module is driven by a high-precision linear servo module, and achieves real-time closed-loop speed matching with the adhesive film release motor through a PLC control system, with a response frequency ≥100Hz, ensuring that the speed difference throughout the bonding process is ≤5mm / s; the moving path of the bonding execution module remains parallel to the wafer surface, and the moving height control accuracy is ≤±5um.

[0037] Programmable pressing mechanism: The pressing rollers are made of medical-grade silicone material, with a diameter of 50mm, a width of 100mm, and a surface hardness of Shore A 70. The rollers are mounted on a high-precision linear servo module, and the movement speed can be precisely set by the program. The pressing pressure is provided by a precision pneumatic cylinder, with a pressure adjustment range of 0.1-0.5MPa and a pressure control accuracy of ±0.01MPa, ensuring that the stress balance formed by the tension-free bonding is not disrupted during the pressing process.

[0038] Circular cutting mechanism: A tungsten steel circular rotary cutting blade with a blade thickness of 0.1 mm and a rotation speed of 3000 rpm is selected. During the cutting process, the wafer is fixed by a vacuum adsorption stage with an adsorption pressure set to -85 kPa. The gap between the cutting blade and the edge of the wafer can be precisely adjusted, and in this embodiment, it is set to 0.1 mm. The linear speed of the cutting blade is synchronized with the linear speed of the wafer rotation in real time to avoid stretching of the film during the cutting process.

[0039] Control system: The Siemens PLC controller is used as the core control unit, and a 10-inch industrial touch screen is used to realize parameter setting and status monitoring. The control system has a built-in process parameter database, which can store a complete set of film bonding process parameters for wafers of different specifications from 6 to 12 inches. It supports parameter customization, one-click import and recall, and realizes closed-loop control of the entire process of tension-free bonding.

[0040] The specific implementation steps of this embodiment are as follows: Step (1) Automatic wafer loading A front-opening wafer transfer box (FOUP) containing 25 8-inch wafers to be coated is placed in the feeding station of the cleanroom. The FOUP is fixed to the cavity by positioning pins with a positioning accuracy of ≤±0.1mm. The operator starts the automatic film application program via the touch screen. The PLC controller sends instructions to the vacuum adsorption robotic arm. The robotic arm moves above the corresponding wafer slot in the FOUP, and the vacuum adsorption circuit is activated. The adsorption status is detected in real time by the pressure sensor. After confirming that the adsorption pressure is stable at -80KPa±5KPa and the adsorption is successful, the wafer is smoothly removed from the FOUP. The robotic arm smoothly transfers the wafer to the vacuum adsorption stage of the lamination station according to the preset safety path. The vacuum adsorption stage starts vacuum adsorption, and the adsorption pressure is set to -85KPa. After the wafer is firmly fixed, the robotic arm returns to the standby position, completing the automatic wafer loading. There is no human contact throughout the process, which provides a stable station benchmark for subsequent tension-free lamination.

[0041] Step (2) Visual alignment The ring-shaped shadowless LED light source of the machine vision alignment system is turned on, and the industrial camera performs full-area shooting of the wafer fixed on the film-coating station, acquires high-definition images of the wafer surface and transmits them to the image processing unit in real time. The image processing unit accurately identifies the V-shaped notch features of the wafer through a pre-trained template matching algorithm, calculates and determines the center coordinates and circumferential angle of the wafer, and outputs the actual position parameters (X1, Y1, θ1) of the wafer. The adhesive film release mechanism pre-releases an adhesive film with a length of 250mm, so that the adhesive film flatly covers the bonding reference surface above the wafer. The industrial camera takes a picture of the adhesive film and identifies the circular positioning marks on the adhesive film through a sub-pixel edge detection algorithm, and calculates and determines the actual position parameters (X2, Y2, θ2) of the adhesive film. The image processing unit feeds back the position parameters of the wafer and the adhesive film to the PLC controller in real time. The PLC controller calculates the position deviation values ​​(ΔX=X2-X1, ΔY=Y2-Y1, Δθ=θ2-θ1) and drives the XYθ three-axis fine-tuning platform of the film-laying station to perform position compensation. The adjustment accuracy of the fine-tuning platform is ±0.005mm, until the position deviation meets ΔX≤±0.008mm, ΔY≤±0.008mm, and Δθ≤±0.1°, thus completing the high-precision alignment of the wafer and the adhesive film and ensuring accurate matching of the coverage area of ​​the adhesive film and the wafer during the subsequent tension-free bonding process.

[0042] Step (3) Tension-free adhesive film bonding (core process step) The PLC controller retrieves the tensionless bonding parameters adapted to the 8-inch wafer from the process database, presets the adhesive film release mechanism's adhesive film output speed to 2m / min, and sets the moving speed of the adhesive film bonding actuator to be matched with the adhesive film output speed in real time in a closed loop, with the speed difference between the two controlled within ≤5mm / s. The adhesive film release mechanism and the bonding execution mechanism start synchronously. The bonding execution mechanism starts from the V-shaped notch end of the wafer and moves at a constant speed along the wafer diameter to the other end. The adhesive film naturally and smoothly covers the wafer surface without any external traction or tension, relying only on its own flatness. During the bonding process, the PLC control system collects the speed signals of the adhesive film release motor and the servo motor of the bonding execution module in real time through the encoder, and performs real-time closed-loop feedback and dynamic adjustment with a response frequency of ≥100Hz to ensure stable speed matching accuracy throughout the process. At the same time, the moving path of the bonding execution mechanism is kept absolutely parallel to the wafer surface, and the moving height error is controlled within ≤±5um. The distance between the adhesive film and the wafer surface remains constant, avoiding local tension concentration caused by the adhesive film contacting the wafer prematurely. This truly achieves tension-free floating bonding throughout the process and eliminates residual internal stress of the adhesive film from the root.

[0043] Step (4) Programmed pressing After tension-free bonding is completed, the PLC controller retrieves the preset bonding parameters from the process database: the roller pressure is set to 0.3MPa and the roller movement speed is set to 10mm / s; The pressing roller descends to contact the surface of the adhesive film and reaches the preset pressure. It starts from the V-shaped notch end of the wafer and moves unidirectionally and uniformly along the wafer diameter to the other end. Through stable pressure and uniform movement, it completes the uniform pressing of the adhesive film and the wafer, eliminates micro-bubbles at the bonding interface, and solidifies the tension-free bonding effect without disrupting the stress balance of the bonding interface. During the pressing process, a high-precision pressure sensor provides real-time feedback of the pressing force signal. If a pressure fluctuation exceeding ±0.01MPa is detected, the PLC controller automatically adjusts the air intake of the pneumatic cylinder to compensate for the pressure deviation in real time and maintain the pressing force stable throughout the process.

[0044] Step (5) Cutting off excess adhesive film After lamination, the vacuum adsorption stage at the film application station drives the wafer to rotate at a constant speed of 50 rpm, with a rotation accuracy of ≤ ±0.1°. The ring-shaped cutting blade descends precisely in the Z-axis direction to contact the surface of the adhesive film, with the contact pressure set at 0.02MPa. At the same time, the cutting blade moves synchronously along the tangent direction of the wafer edge, and the cutting speed is completely synchronized with the rotational speed of the wafer. The cutting speed is set at 20mm / s, and the blade completes a full ring cut along the wafer contour, precisely removing the excess adhesive film that extends beyond the wafer edge. During the cutting process, the gap between the cutting blade and the wafer edge is kept stable at 0.1mm to avoid film stretching, stress release, or wafer edge chipping during the cutting process, ensuring the stability of the interface after tension-free bonding; after the cutting is completed, the cutting blade automatically resets, the vacuum adsorption stage stops rotating, and the excess film removed is automatically recycled by the negative pressure waste collection device.

[0045] Step (6) Automatic unloading of finished products The vacuum adsorption robotic arm moves to the top of the film application station, the vacuum adsorption circuit is activated, and after the adsorption pressure stabilizes at -80KPa, it adsorbs the wafers that have been coated. At the same time, the vacuum adsorption stage of the film application station releases the vacuum. The robotic arm smoothly transfers the finished wafers into the finished product FOUP according to the preset path, and places them in the preset slot order to avoid collisions and scratches between the wafers; Once the finished FOUP is filled with 25 wafers, the PLC controller sends an audible and visual alert via the touchscreen to notify the operator to replace the empty FOUP and continue with the next batch of film application, thus completing the entire fully automated film application process.

[0046] Implementation effect verification In this embodiment, 1000 8-inch silicon-based wafers were selected for mass production verification. After the film was applied using the method described above, the wafers were sent to the wafer grinding process for back-side thinning (the wafer thickness after grinding was 80μm). The film application effect and wafer performance were comprehensively tested using professional equipment, and the results are as follows: Warpage Improvement: The warpage of the polished wafers was tested using a wafer warpage tester (model: TROPELFlatMaster200). The results showed that the maximum warpage of all wafers was ≤0.03mm, and the average warpage was only 0.015mm. Compared with the traditional film lamination process (average warpage 0.08mm), the warpage improvement rate reached 81.25%, and the wafer breakage rate was 0, completely solving the warpage and breakage problems of the traditional process.

[0047] Contamination control effect: The particle count on the wafer surface after film application was detected by a wafer surface particle detector (model: KLA-TencorSurfscanSP1). The results showed that the number of particles larger than 0.5μm on all wafer surfaces was ≤3 per wafer, with no visible dirt marks. The contamination rate was reduced to below 0.3%, which is far lower than the contamination rate of traditional film application processes.

[0048] Alignment accuracy and process consistency: The alignment error of the film on all wafers is ≤ ±0.008mm, the wafer edges are completely covered, and there are no chipped corners or film offset. The film bonding strength of 100 wafers was sampled and tested by a tensile tester (test speed 5mm / min). The results showed that the coefficient of variation of bonding strength was ≤2.8%, which is far lower than the 15% coefficient of variation of traditional film bonding process, and the process consistency has been significantly improved.

[0049] Operational efficiency: The film application process in this embodiment has a single-wafer cycle of only 55 seconds, and can stably complete the film application of 65 wafers per hour. Compared with traditional fully automatic film application equipment, the operational efficiency is improved by more than 120%, which perfectly matches the operation rhythm of subsequent grinding and cutting equipment and effectively breaks through the capacity bottleneck of mass production line.

[0050] Parameter adaptation for wafers of different specifications The method of this invention can be adapted to the film application requirements of wafers of all sizes from 6 to 12 inches. Process switching can be quickly completed simply by adjusting the corresponding process parameters through the process database of the control system. The core parameter adjustment rules are as follows: Adsorption pressure parameters: For 6-inch and smaller wafers, the robotic arm adsorption pressure is set to -80KPa to -75KPa; for 12-inch wafers, the robotic arm adsorption pressure is set to -90KPa to -85KPa. Visual alignment parameters: Based on the notch / flat edge dimensions of wafers of different specifications, update the alignment template library and adjust the template matching threshold to ensure that the alignment accuracy is stable at ≤±0.01mm; Tension-free bonding parameters: For wafers of 6 inches and below, the adhesive film release speed and the moving speed of the bonding actuator are set to 1-1.5 m / min; for 12-inch wafers, the adhesive film release speed and the moving speed of the bonding actuator are set to 2.5-3 m / min, and the speed difference is always controlled within ≤5 mm / s throughout the process. Lamination parameters: For 6-inch and smaller wafers, the lamination pressure is set to 0.1-0.2MPa and the roller movement speed is set to 8mm / s; for 12-inch wafers, the lamination pressure is set to 0.4-0.5MPa and the roller movement speed is set to 12mm / s. Cutting parameters: Adjust the circumferential cutting radius of the dicing blade according to the wafer diameter, keep the gap between the dicing blade and the wafer edge within the range of 0.1-0.2mm, and keep the cutting line speed synchronized with the wafer rotation line speed.

[0051] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes, substitutions, and modifications made by those skilled in the art based on the core concept of the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. An automated wafer lamination method, characterized in that, The core process, which uses tension-free adhesive bonding, includes the following steps: (1) Automatic wafer loading: The wafer to be coated is transferred to the vacuum adsorption stage of the coating station by a mechanical transfer mechanism to complete the positioning and fixing. The entire transfer process is free from direct contact between the human body and the wafer. (2) Visual alignment: A machine vision recognition system is used to collect the notch or flat edge features of the wafer and the positioning reference features of the adhesive film. Based on the preset alignment algorithm, the wafer and the adhesive film are aligned with high precision, providing a precise position reference for tension-free adhesive application. (3) Tensionless adhesive film bonding: control the adhesive film output speed of the adhesive film release mechanism to match the moving speed of the adhesive film bonding execution mechanism in real time in a closed loop, so as to ensure that no additional tensile tension is generated during the process of covering the wafer surface, and realize tensionless floating bonding between the adhesive film and the wafer surface. (4) Programmed pressing: By pre-setting constant pressing parameters, the pressing rollers perform unidirectional uniform pressing on the adhesive film and wafer that have completed tensionless bonding, solidify the bonding effect and eliminate residual stress. The pressing parameters include roller pressure and roller movement speed. (5) Excess adhesive film cutting: The excess adhesive film is cut synchronously and precisely along the edge contour of the wafer using a ring cutting mechanism to avoid damaging the stable interface formed by tensionless bonding during the cutting process; (6) Automatic unloading of finished products: The wafers after film application are transferred from the film application station to the finished product storage area through a mechanical transmission mechanism to complete the entire film application process; By using the core tension-free bonding design in step (3) and the programmed pressing control in step (4), the problem of uneven tension and residual internal stress in the adhesive film bonding process is completely eliminated, thereby improving the warping and deformation phenomenon in the subsequent grinding and etching processes of the wafer from the root and reducing the breakage rate of thin wafers.

2. The automated wafer bonding method according to claim 1, characterized in that, In step (1), the mechanical transmission mechanism is a vacuum adsorption robotic arm. The entire process of transfer and film application is carried out in a Class 100 or higher cleanroom environment. The adsorption pressure of the vacuum adsorption robotic arm is -90KPa to -75KPa, which avoids particulate contamination or physical damage to the wafer surface and provides a clean and stable working basis for tension-free bonding.

3. The automated wafer bonding method according to claim 1, characterized in that, In step (2), the machine vision recognition system includes a ring light source module and an image processing unit. The alignment accuracy error between the wafer and the adhesive film is ≤ ±0.01mm. The image processing unit identifies the notch or flat edge features of the wafer through a template matching algorithm and identifies the positioning reference features of the adhesive film through an edge detection algorithm, ensuring that the coverage area of ​​the adhesive film and the wafer is accurately matched during the tension-free bonding process.

4. The automated wafer bonding method according to claim 1, characterized in that, In step (3), the real-time difference between the adhesive film output speed of the adhesive film release mechanism and the moving speed of the adhesive film bonding actuator is ≤5mm / s; the moving path of the adhesive film bonding actuator is kept absolutely parallel to the wafer surface, and the moving height error is ≤±5um, ensuring that the adhesive film is not stretched locally or prematurely contacted during the bonding process, thus achieving tension-free bonding throughout the process.

5. The automated wafer bonding method according to claim 1, characterized in that, In step (4), the preset range of the roller pressure is 0.1-0.5MPa, the preset range of the roller movement speed is 10-100mm / s, and the surface hardness of the pressing roller is Shore A60-80 degrees. The pressing process adopts a unidirectional uniform speed pressing method, that is, the pressing roller moves from one end of the wafer to the other end at a uniform speed to ensure that the pressing force is uniformly transmitted to the bonding interface between the adhesive film and the wafer, without disrupting the stress balance formed by tensionless bonding.

6. The automated wafer bonding method according to claim 1, characterized in that, In step (5), the gap between the blade of the ring cutting mechanism and the edge of the wafer is ≤0.2mm, the cutting speed is completely synchronized with the rotational speed of the wafer, and the cutting speed range is 5-30mm / s. This avoids film stretching, stress release or wafer edge chipping during the cutting process, and ensures the interface stability after tension-free bonding.

7. The automated wafer bonding method according to claim 1, characterized in that, In step (3), both the adhesive film release mechanism and the adhesive film bonding execution mechanism are driven by servo motors. The speed is controlled by a PLC control system to achieve real-time closed-loop feedback and dynamic adjustment. The response frequency is ≥100Hz, ensuring stable speed matching accuracy and no tension fluctuation throughout the bonding process.

8. The automated wafer bonding method according to claim 1, characterized in that, All execution parameters for each step are stored in the process database module of the control system. The process database module supports custom editing and one-click recall of parameters. It can quickly match the corresponding tension-free bonding parameters, pressing parameters, and cutting parameters according to the film bonding requirements of wafers of different sizes from 6 to 12 inches, ensuring the consistency of tension-free film bonding effect for wafers of different sizes.

9. The automated wafer bonding method according to claim 1, characterized in that, In step (3), during the tensionless adhesive film bonding process, the adhesive film naturally covers the wafer surface by relying solely on its own flatness, without any external traction or tensile force applied to the adhesive film. The residual internal stress after adhesive film bonding is reduced by more than 90% compared to traditional traction bonding.

10. The automated wafer bonding method according to claim 1, characterized in that, The entire process from step (1) to step (6) is completed in a closed cleanroom without any human intervention, achieving fully automated and unmanned operation of wafer lamination, while ensuring the environmental stability of the tension-free lamination process.

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