Semiconductor wafer pod handling system and control method thereof

Abstract

The application discloses a semiconductor wafer bin conveying system and a control method thereof, and relates to the technical field of semiconductor manufacturing automation. The system comprises a conveying unit and a material placing unit. The improvement lies in that the bottom of a wafer bin body is provided with three positioning grooves in isosceles triangle distribution, forming a mistaken orientation prevention structure; and the transfer frame and the material placing frame are respectively provided with a first set and a second set of limiting protrusions corresponding to the positioning grooves. The two sets of protrusions are configured to be selectively and sequentially clamped with the positioning grooves at the bottom of the same bin body during the conveying process, so that the anti-interference positioning handover from grabbing to placing is realized. The application eliminates the positioning collision risk between the conveying mechanism and the fixed station from the mechanical structure, and ensures the uniqueness of the direction of the wafer bin through the asymmetric geometric design. Meanwhile, the material placing frame can be integrated with elastic air supply and pressure sensing detection functions, realizing higher automation and reliability.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing and automation technology, specifically to an automated system and control method for handling semiconductor wafer pods (FOUP, SMIF Pod, etc.), and in particular to a handling system with anti-interference precise positioning and anti-misorientation functions. Background Technology

[0002] In the semiconductor front-end process, wafers are typically placed in standardized wafer silos and frequently transferred between different processing equipment and storage racks. Currently, the wafer silo handover between automated material handling systems (AMHS), such as stacker cranes (OHT / AGVs) and the load ports of equipment front-end modules (EFEMs), usually uses simple forks inserted into grooves at the bottom of the silo for gripping and placing.

[0003] However, existing technologies have the following prominent problems:

[0004] Positioning interference risk: The fork teeth (or limit protrusions) of the conveying mechanism and the positioning pins on the fixed placement rack (such as the Load Port) usually share a positioning reference. During the placement operation, if the fork teeth of the conveying mechanism are not completely disengaged in time, they are very likely to mechanically interfere with the positioning pins of the placement rack, resulting in inaccurate positioning, equipment jamming, or component damage.

[0005] Risk of misalignment: The positioning structure at the bottom of many wafer silos is symmetrical or simply distributed. If there is a deviation in visual recognition or an error in the control program, the silo may be rotated 180 degrees and misplaced, causing a serious production accident.

[0006] Limited functionality: Traditional material racks only provide simple mechanical positioning. Functions such as air circuit connection and position confirmation required by the wafer hopper need to be achieved through additional independent mechanisms. The system has low integration, large space occupation, and complex operation process.

[0007] Therefore, there is an urgent need for a wafer warehousing handling system that can solve the above-mentioned positioning interference and orientation misjudgment problems, and achieve higher integration and reliability. Summary of the Invention

[0008] The present invention aims to overcome the shortcomings of the prior art and provide a semiconductor wafer warehousing handling system and control method that can achieve precise positioning with anti-interference and anti-misorientation capabilities and high integration.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a semiconductor wafer silo handling system, including a handling unit and a material placement unit.

[0011] The handling unit includes a transfer frame and a robotic arm that drives its movement. The transfer frame is equipped with a limiting frame, and guide limiting plates on both sides of the limiting frame are used for guiding and clamping the wafer hopper. The handling unit typically also includes a vision inspection system, which may include a fixedly installed first vision system (for identifying the bottom state of the wafer hopper when it is forked) and an adjustable-angle second vision system (for identifying the mating state of the wafer hopper after it is placed on the loading rack).

[0012] The material placement unit includes a fixedly installed material placement rack, which has a semi-open clearance groove for cooperating with the transfer rack to avoid and initially guide the transfer rack during placement. The material placement rack may also integrate an elastic air supply structure (for automatic connection with the gas path of the wafer cassette) and an elastic pressure-sensitive structure (for detecting whether the wafer cassette is placed in place).

[0013] The core improvement of this invention lies in the way the bottom positioning structure of the wafer hopper cooperates with the handling and loading unit:

[0014] The bottom of the wafer cascade is provided with a cascade support plate, on which three positioning slots are formed in a specific geometric distribution, preferably an isosceles triangle, including a first positioning slot, a second positioning slot, and a third positioning slot. The second and third positioning slots are symmetrically arranged, and the first positioning slot is located at the apex of the isosceles triangle. This asymmetrical isosceles triangular layout gives the wafer cascade a unique orientation.

[0015] Accordingly, the transfer rack is provided with a first set of limiting protrusions corresponding to the three positioning slots; the material placement rack is provided with a second set of limiting protrusions corresponding to the three positioning slots.

[0016] The key design feature is that the first and second sets of limiting protrusions are configured to engage sequentially and selectively with the positioning groove at the bottom of the same wafer hopper during transport. Specifically, when the transfer rack picks up the hopper, only the first set of protrusions engages with the positioning groove; when the hopper is placed on the placement rack, the second set of protrusions on the placement rack engages with the positioning groove, while the first set of protrusions on the transfer rack simultaneously retracts. This "dual-interface, single-time-slot" design completely eliminates the possibility of positioning interference between the transport mechanism and the fixed workstation from a physical structural perspective.

[0017] Furthermore, the transfer rack can adopt a structure that can be extended and retracted back and forth, which is achieved through linear guide rails and reciprocating drive mechanism, so as to adapt to wafer hoppers of different sizes or finely adjust the insertion depth and avoid collisions.

[0018] Secondly, the present invention provides a semiconductor wafer warehouse handling control method based on the above system.

[0019] The method includes the following steps: using a vision system to locate and identify the target wafer hopper, confirming the direction of its bottom isosceles triangular positioning groove; controlling a robotic arm to drive the transfer frame to move, aligning its first set of limiting protrusions with and engaging with the positioning groove at the bottom of the wafer hopper, completing the gripping; transporting the wafer hopper to above the target placement rack; controlling the transfer frame to descend, aligning and engaging the positioning groove at the bottom of the hopper with the second set of limiting protrusions on the placement rack, while the first set of protrusions disengages; and receiving a confirmation signal from the placement rack (such as an elastic pressure-sensitive structure) to confirm the arrival of the wafer hopper, controlling the transport unit to move away.

[0020] The beneficial effects of this invention are as follows:

[0021] Fundamental anti-interference: By using two sets of independent limiting protrusions on the transfer rack and the placement rack, and the "selective" cooperation mechanism between the two and the wafer hopper positioning slot, the risk of collision between positioning components during handling and placement is eliminated from a mechanical principle.

[0022] Physical error prevention and orientation uniqueness: The positioning slots are asymmetrically distributed in isosceles triangles, which, together with the orientation recognition of the vision system, ensure that the wafer tray is absolutely oriented correctly when grasping and placing, preventing the major risk of 180-degree misplacement.

[0023] High integration and intelligence: The material rack integrates flexible air supply and pressure detection functions, realizing automatic air circuit docking and real-time and reliable feedback of placement status, simplifying peripheral equipment and improving the system's automation level and reliability.

[0024] High compatibility and reliability: Adjustable transfer rack, limit protrusion with guide ramp, and avoidance groove design enhance the adaptability to different specifications of silos, reduce assembly accuracy requirements, and improve the system's fault tolerance and operational smoothness. Attached Figure Description

[0025] Figure 1 This is a three-dimensional schematic diagram of the overall structure of an embodiment of the present invention;

[0026] Figure 2 This is a three-dimensional schematic diagram of the material rack in this invention;

[0027] Figure 3 This is a schematic diagram of the bottom of the wafer cascade, showing the distribution of the positioning slots;

[0028] Figure 4 This is a top view of an adjustable transfer frame according to another embodiment of the present invention.

[0029] 1-Fixed base, 2-Robot arm, 3-Transfer frame, 31-Limiting frame, 4-Placing rack, 41-Semi-open clearance slot, 5-Wafer housing, 51-Hospital support plate, 53-First positioning slot, 54-Second positioning slot, 55-Third positioning slot, 11-External fixing frame, 12-First vision fixing frame, 13-First vision system, 14-Second vision system. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0031] Example 1: See Figures 1 to 3 This embodiment provides a semiconductor wafer silo handling system. The system includes a handling unit and one or more loading units.

[0032] The main body of the handling unit is a six-axis or SCARA type robot arm 2, which is fixed to a fixed base 1. An external mounting bracket 11 is installed on the outer periphery of the fixed base 1, and a first vision system 13 (such as a fixed-focus industrial camera) is mounted on it via a first vision mounting bracket 12. A second vision system 14 (such as a variable-focus industrial camera with a gimbal) is installed on the other side of the fixed base 1. A transfer frame 3 is connected to the end flange of the robot arm 2. A limit frame 31 is welded or bolted to the transfer frame 3. A pair of guide limit plates are installed parallel to each other on both sides of the limit frame 31. The inner side of the pair of guide limit plates can be glued with a buffer and wear-resistant liner such as polyurethane to protect the wafer cascade 5. The lower surface of the transfer frame 3 has three cylindrical or wedge-shaped first set of limit protrusions arranged in an isosceles triangle (not shown separately in the figure), the positions of which correspond precisely to the positioning grooves at the bottom of the wafer cascade 5.

[0033] The material placement unit is mainly a fixedly installed material placement rack 4. (See reference...) Figure 2 The material rack 4 has a semi-open recess 41 in the center, the shape of which matches the cross-section of the transfer rack 3, used to accommodate the transfer rack 3 and guide it into the correct position during placement. The upper surface of the material rack 4 has three second set of limiting protrusions arranged in isosceles triangles (not shown separately in the figure). The material rack 4 integrates an elastic air supply structure (such as a spring-loaded valve) and an elastic pressure-sensitive structure (such as a micro switch or pressure sensor), the movable end of which protrudes slightly from the upper surface.

[0034] See Figure 3The bottom of the wafer housing 5 is provided with a metal housing support plate 51. Three positioning slots are machined on the housing support plate 51: the second positioning slot 54 and the third positioning slot 55 are symmetrically formed, and the line connecting them forms the base of an isosceles triangle; the first positioning slot 53 is formed at the apex of the perpendicular line from the base, forming an isosceles triangle together with the two points of the base. The depth and shape of the three positioning slots are designed to simultaneously accommodate the first set of protrusions of the transfer rack 3 or the second set of protrusions of the placement rack 4, but the depth is insufficient to accommodate both simultaneously.

[0035] Workflow:

[0036] Visual positioning: The handling unit moves to the vicinity of the target wafer storage unit 5. The first vision system 13 takes a picture of the bottom of the storage unit and identifies the isosceles triangle distribution of the three positioning slots, thereby uniquely determining the orientation of the storage unit. The system calculates the gripping position.

[0037] Grasping the container: The robotic arm 2 drives the transfer frame 3 to move, causing its guide and limiting plates to approach and guide the container from both sides. Simultaneously, the first set of limiting protrusions under the transfer frame 3 precisely inserts into the first, second, and third positioning slots at the bottom of the container. At this point, the transfer frame 3 bears the weight of the container, completing the grasping process. The second vision system 14 can rotate to confirm that the protrusions and slots are properly aligned.

[0038] Transport and pre-alignment: The robotic arm 2 moves the bin 5 above the target placement rack 4. During this process, the system controls the transfer rack 3 (if adjustable) to make necessary fine adjustments.

[0039] Interference-free placement: The robotic arm 2 drives the transfer frame 3 to descend. As the bin 5 approaches the placement rack 4, the transfer frame 3 first enters the semi-open clearance groove 41 for coarse guidance. As it continues to descend, the positioning groove at the bottom of the bin 5 first contacts and aligns with the second set of limiting protrusions on the placement rack 4. At the instant the second set of protrusions is fully inserted into the positioning groove, the first set of protrusions on the transfer frame 3 precisely exits from the other end of the same positioning groove. This process achieves a seamless handover of positioning responsibility without any interference risk. The weight of the bin 5 is entirely borne by the placement rack 4.

[0040] Functional connection and confirmation: After the bin is placed in place, the elastic air supply structure on the material rack 4 is pushed out and sealed to the air hole at the bottom of the bin; at the same time, the elastic pressure-sensitive structure is triggered and sends a confirmation signal of "placement in place".

[0041] Transfer unit removal: After receiving the arrival signal, the control system controls the robotic arm 2 to lift the transfer frame 3, so that its first set of protrusions completely detaches from the warehouse area, the transfer unit is moved away, and the process ends.

[0042] Example 2: See Figure 4The main difference between this embodiment and Embodiment 1 lies in the structure of the transfer frame 3. In this embodiment, the transfer frame 3 is designed as an adjustable transfer frame. Specifically, the transfer frame 3 is mounted on a base plate at the end of the robot arm via a set of precision linear guides and is driven by a ball screw (a type of reciprocating drive mechanism) driven by a servo motor, allowing for precise forward and backward extension relative to the base plate.

[0043] When handling ultra-thin wafer silos or wafers with special bottom structures, the operator or control system can program the transfer rack 3 to extend forward a certain distance, allowing the limiting rack 31 to grip the silo more deeply and safely, or to avoid collisions when entering narrow spaces. This adjustable feature greatly enhances the system's adaptability and safety.

[0044] Example 3: In this example, the functional modules integrated on the material rack 4 are described in detail. The elastic air supply structure includes a spring-loaded floating joint and a built-in air circuit on / off valve. When the bin is not placed, the floating joint retracts slightly under the action of the spring. When the bin is placed in position and the floating joint is pressed down a certain distance, the air circuit is automatically opened, and clean dry air (CDA) or nitrogen is supplied to the bin. The elastic pressure-sensitive structure is a high-precision miniature weighing sensor or a regional pressure sensing film, integrated under the bearing surface of the material rack 4. When the detected pressure value reaches the preset bin weight threshold, it is determined that the bin is in place, making the signal more reliable.

[0045] Example 4: In this example, the first set of limiting protrusions on the transfer frame 3 and the second set of limiting protrusions on the placement frame 4 are both machined with conical or wedge-shaped guide slopes at their top ends. This allows the hopper to be forced to make slight movements through the guiding effect of the slopes when there is a slight deviation between the protrusions and the positioning grooves, ultimately leading to smooth insertion and achieving "active correction," thus reducing the stringent requirements for the absolute positioning accuracy of the robot arm.

[0046] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A semiconductor wafer silo handling system, characterized in that, Includes a conveying unit and a loading unit: The transport unit includes a transfer frame (3) and a robotic arm (2) that drives its movement. The transfer frame (3) is provided with a limiting frame (31), and the limiting frame (31) is provided with guide limiting plates on both sides for guiding and clamping the wafer hopper (5). The material placement unit includes a fixedly installed material placement rack (4), and the material placement rack (4) is provided with a semi-open clearance groove (41) for cooperating with the transfer rack (3). The bottom of the wafer storage body (5) is provided with a storage body support plate (51). The storage body support plate (51) is provided with three positioning grooves distributed in an isosceles triangle, including a first positioning groove (53), a second positioning groove (54) and a third positioning groove (55). The second positioning groove (54) and the third positioning groove (55) are symmetrically arranged, and the first positioning groove (53) is located at the apex of the isosceles triangle. The transfer frame (3) is provided with a first set of limiting protrusions that correspond one-to-one with the three positioning slots; The material rack (4) is provided with a second set of limiting protrusions that correspond one-to-one with the three positioning slots; The first set of limiting protrusions and the second set of limiting protrusions are configured such that, during the handling process, they can sequentially and selectively engage with the positioning groove at the bottom of the same wafer hopper (5) to achieve interference-free precise positioning and directional uniqueness constraint of the wafer hopper (5) between the gripping position and the placement position.

2. The semiconductor wafer silo handling system according to claim 1, characterized in that, The material rack (4) is also integrated with an elastic air supply structure, which is used to automatically connect the gas path of the wafer hopper (5) after it is placed in place.

3. The semiconductor wafer silo handling system according to claim 1 or 2, characterized in that, The material rack (4) also integrates an elastic pressure-sensitive structure for detecting whether the wafer hopper (5) is placed in place.

4. The semiconductor wafer silo handling system according to claim 1, characterized in that, The handling unit also includes a vision inspection system, which includes a fixedly installed first vision system (13) and an angle-adjustable second vision system (14), used to identify the bottom state of the wafer hopper when it is forked and the fit state after it is placed behind the rack.

5. The semiconductor wafer silo handling system according to claim 1, characterized in that, The transfer frame (3) is an adjustable transfer frame that achieves forward and backward extension through a linear guide rail and a reciprocating drive mechanism.

6. The semiconductor wafer silo handling system according to claim 1, characterized in that, The shape of the opening side of the semi-open avoidance groove (41) is adapted to the cross-sectional shape of the transfer frame (3) and is used to initially guide and avoid the transfer frame (3) during placement.

7. The semiconductor wafer silo handling system according to claim 1, characterized in that, The inner side of the guide limiting plate is provided with a buffer or wear-resistant lining.

8. The semiconductor wafer silo handling system according to claim 1, characterized in that, Of the first set of limiting protrusions and the second set of limiting protrusions, at least one set of protrusions is a conical or wedge-shaped protrusion with a sloping guide portion.

9. The semiconductor wafer silo handling system according to claim 4, characterized in that, The system also includes a fixed base (1), on which the robotic arm (2) is mounted. The outer periphery of the fixed base (1) is provided with an external mounting bracket (11) and a first vision mounting bracket (12) for supporting the first vision system (13).

10. A semiconductor wafer silo handling control method based on the system according to any one of claims 1-9, characterized in that, Includes the following steps: The target wafer housing (5) is located and identified by a vision system to confirm the direction of the isosceles triangular positioning slot group at its bottom; The control robot (2) drives the transfer frame (3) to move and adjust its posture so that its first set of limiting protrusions are precisely aligned with the corresponding positioning groove at the bottom of the wafer hopper (5) and snapped in, thus completing the gripping; Transport the wafer hopper (5) above the target rack (4); Control the transfer rack (3) to descend, so that the positioning groove at the bottom of the wafer hopper (5) aligns and engages with the second set of limiting protrusions on the material rack (4), while the first set of limiting protrusions disengages. After receiving the arrival confirmation signal from the material rack (4), the control transport unit moves away to complete the anti-interference transport process.

Images