Pre-alignment method and pre-alignment device

Abstract

This invention relates to the field of semiconductor technology and provides a pre-alignment method and apparatus. The pre-alignment method includes: S1: acquiring edge information of the wafer to obtain the eccentricity, and adjusting the wafer position to compensate for the eccentricity; S2: acquiring scribe line image information of the upper surface of the wafer to obtain the actual direction of the scribe line, and rotating the wafer to adjust the direction of the scribe line to a specified direction; S3: acquiring edge image information of the edge of the upper surface of the wafer located within the illumination area, and matching the edge image information with the notch of the template to obtain the notch position of the wafer and complete the orientation. This method is suitable for the pre-alignment of wafers where the notch morphology has changed drastically, which helps to improve work efficiency and facilitates automated alignment operations.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a pre-alignment method and pre-alignment apparatus. Background Technology

[0002] Wafer pre-alignment is a crucial module of the transfer subsystem. The transfer robot retrieves the wafer from the wafer memory, and after being centered and oriented by the wafer pre-alignment equipment, it is lifted onto the worktable and then moved to the alignment station for alignment. This requires that after the wafer is initially positioned by the pre-alignment equipment, the markings on the wafer must be within the alignment field of view. Because wafer markings have high positional accuracy relative to the wafer's geometric features, wafer pre-alignment achieves wafer centering based on the outer circular geometry and wafer orientation based on edge notches or flat edges. The orientation method typically involves providing illumination from top to bottom towards the wafer's edge, using the brightness of the illumination to distinguish and identify notches.

[0003] In wafer processing, certain processes can cause changes in the appearance of notches on the wafer.

[0004] Taking TSV (Through Silicon Via) technology as an example, TSV is a cutting-edge technology that enables interconnection between chips by creating vertical conductions between chips and wafers. It has advantages such as small package size, fast signal transmission, and low power consumption.

[0005] After undergoing various TSV processes, the edges of a standard wafer exhibit the following characteristics: misalignment and non-concentric bonding, edge wear, scribe lines, sputtered metal or residual adhesive on the wafer surface, and wafer warping. Wafer notches manifest as: incomplete notches, damage, filling or covering with metal or adhesive, or the presence of metal traces.

[0006] Therefore, when the wafer notch morphology changes drastically due to the processing technology, the conventional method of identifying notches by light intensity cannot meet the wafer pre-alignment accuracy requirements.

[0007] Currently, for wafers with drastic changes in notch morphology, an aligner is generally used for wafer exposure. The aligner does not consider the changes in the wafer's notch morphology; it involves direct manual alignment of the markings before exposure. This wafer pre-alignment method suffers from low efficiency, low pre-alignment accuracy, and the inability to achieve automated operation due to the susceptibility of pre-alignment accuracy to human error.

[0008] Based on this, a pre-alignment method and pre-alignment device are proposed. This method is suitable for the pre-alignment of wafers with drastic changes in notch morphology, which helps to improve work efficiency and facilitates automated alignment operations. Summary of the Invention

[0009] The invention provides a pre-alignment method and pre-alignment apparatus. The method is suitable for pre-alignment of wafers whose notch morphology has undergone drastic changes, which helps to improve work efficiency and facilitates automated alignment operations.

[0010] The pre-alignment method includes the following steps;

[0011] S1: Collect edge information of the wafer to obtain the eccentricity, and adjust the wafer position to compensate for the wafer eccentricity;

[0012] S2: Acquire image information of the scribing grooves on the upper surface of the wafer, obtain the actual direction of the scribing grooves, and rotate the wafer to adjust the direction of the scribing grooves to the specified direction;

[0013] S3: Acquire edge image information of the edge of the upper surface of the wafer located within the illumination area, and match the edge image information with the notch of the template to obtain the notch position of the wafer and complete the orientation.

[0014] Optionally, in step S3, lateral illumination is provided at the edge of the wafer, and edge image information within the illuminated area is acquired.

[0015] Optionally, in step S3, the wafer is rotated so that the edge of the wafer passes through the illumination area in sequence, and the edge image information of the edge of the upper surface of the wafer located within the illumination area is acquired.

[0016] Optionally, in step S3, the edge image information acquisition includes the following steps:

[0017] S3-1: Using the relative positional relationship between the scribe groove and the notch in the template as a reference, obtain several target positions where the wafer edge may have notches, determine one of the target positions as the initial acquisition position, and make the initial acquisition position located within the illumination area;

[0018] S3-2: Perform edge image information acquisition and image matching at the initial acquisition position. If the matching is successful, the wafer orientation is completed; if the matching is unsuccessful, proceed to step S3-3.

[0019] S3-3: Rotate the wafer to place the next target position within the illumination area, and acquire edge image information of the target position and perform image matching;

[0020] S3-4: If the matching is successful, the wafer orientation is complete; if the matching is unsuccessful, proceed to step S3-3.

[0021] Optionally, the center angle between each of the target positions is 90°.

[0022] Optionally, the specified direction is the direction in which the scribing groove is horizontal and vertical relative to the information acquisition unit.

[0023] Optionally, in step S3, image gradient information of edge image information is calculated, and the gradient information is layered;

[0024] The amount of gradient information contained in each layer increases sequentially;

[0025] Arrange the layers in ascending order of the amount of gradient information they contain, and match the gradient information of each layer with the gradient information of the template in turn;

[0026] If the gradient information of this layer matches the template, then proceed to the next layer for gradient information matching;

[0027] If the gradient information of this layer does not match the template, then edge image information at other locations on the wafer edge will be re-acquired.

[0028] Optionally, in step S1, illumination is provided at the edge of the wafer from bottom to top, and the illumination intensity at the edge of the wafer is detected from above the wafer to extract edge information.

[0029] Optionally, in step S2, the image information of the scribed groove corresponding to a cross-shaped scribed groove is extracted, and the image integral along the straight line trajectory in the scribed groove image information is performed. The actual direction of the scribed groove is obtained based on the peak value of the image integral.

[0030] The present invention also provides a pre-alignment device, including an information acquisition unit, a pre-alignment motion unit, and an information processing unit;

[0031] The information acquisition unit is used to acquire edge information, scribing groove image information, and edge image information of the wafer;

[0032] The information processing unit is used to process edge information and calculate the eccentricity of the wafer, to process the scribing image information to obtain the actual direction of the scribing groove of the wafer, and to process the edge image information to obtain the notch position of the wafer.

[0033] The pre-alignment motion unit is used to drive the wafer movement to compensate for the eccentricity and adjust the direction of the scribe lines on the wafer to the specified direction.

[0034] Optionally, the pre-alignment device further includes a lateral light source;

[0035] The side light source is used to provide illumination to the edge of the wafer, and the information acquisition unit acquires edge image information of the edge of the upper surface of the wafer located within the illumination area of ​​the side light source.

[0036] Alternatively, the side light source provides downward-sloping illumination to the edge of the wafer.

[0037] Optionally, the pre-alignment device further includes a bottom light source, which is used to provide illumination to the edge of the wafer from bottom to top, and to obtain the edge information of the wafer by identifying the light intensity at the edge of the wafer from top to bottom through the information acquisition unit.

[0038] Optionally, the pre-alignment motion unit includes a vertical part, a rotating part, and a translational part;

[0039] The vertical section is used to drive the wafer to make vertical movements;

[0040] The rotating part is used to drive the wafer to rotate along an axis perpendicular to its upper surface;

[0041] The translation section is used to drive the wafer to move horizontally.

[0042] Optionally, the pre-alignment device further includes a point light source, which is used to provide illumination for the scribing grooves on the upper surface of the wafer from top to bottom, and to acquire image information of the scribing grooves on the upper surface of the wafer located within the illumination area of ​​the point light source through an information acquisition unit.

[0043] Optionally, the information acquisition unit includes an acquisition unit and a driving unit;

[0044] The acquisition unit is used to acquire edge information, scribing groove image information, and edge image information of the wafer;

[0045] The drive unit is used to drive the acquisition unit to move;

[0046] And / or, the driving unit is used to drive the lateral light source to move;

[0047] And / or, when the pre-alignment device includes a bottom light source, the driving unit is used to drive the bottom light source to move;

[0048] And / or, when the pre-alignment device includes a point light source, the driving unit is used to drive the point light source to move.

[0049] With this configuration, the present invention, through the aforementioned orientation method, acquires edge information of the wafer to fit the wafer edge, obtains the actual center position, and thus calculates the eccentricity, thereby achieving wafer centering. By acquiring information about the scribing grooves on the wafer surface, the actual direction of the scribing grooves is obtained, and the scribing grooves are rotated to a specified direction to adjust the initial pose of the wafer. Furthermore, based on the relative positional relationship between the scribing grooves and notches in the actual template, several target positions where notches may exist at the wafer edge can be preliminarily determined, facilitating the acquisition of wafer notch positions. Then, illumination is provided to the wafer edge from top to bottom to acquire edge image information within the illuminated area. Utilizing the height difference characteristic at the wafer notch edge, image features are extracted and matched with the template to obtain the wafer notch position, achieving wafer orientation. This alignment method is suitable for the pre-alignment of wafers with drastic changes in notch morphology. It improves the pre-alignment accuracy of wafers with drastic changes in notch morphology, increases the pre-alignment orientation pass rate of wafers, reduces orientation time, and helps improve work efficiency. This alignment method does not require manual intervention, which helps to realize automated alignment operations. It also eliminates human interference factors during the alignment process, solving the problems of low pre-alignment efficiency, low pre-alignment accuracy, and inability to realize automated operations for wafers with drastic changes in notch morphology in the past. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the pre-alignment device according to an embodiment of the present invention;

[0051] Figure 2 A partial structural diagram of a pre-alignment device according to an embodiment of the present invention. Figure 1 ;

[0052] Figure 3 This is a state diagram of wafer alignment according to an embodiment of the present invention;

[0053] Figure 4 Image integration data along the straight line trajectory in the scribed groove image information. Figure 1 ;

[0054] Figure 5 Image integration data along the straight line trajectory in the scribed groove image information. Figure 2 ;

[0055] Figure 6 This is a flowchart for pre-alignment.

[0056] The accompanying figure is labeled as follows:

[0057] 10-Information acquisition unit; 11-Acquisition section; 111-Pre-alignment camera; 112-Pre-alignment lens; 12-Drive section;

[0058] 20 - Pre-alignment motion unit; 21 - Vertical part; 22 - Rotating part; 23 - Translation part; 231 - Second adsorption structure;

[0059] 30 - Side light source;

[0060] 40 - Bottom light source;

[0061] 50-Point light source;

[0062] 60-Wafer. Detailed Implementation

[0063] The pre-alignment method and pre-alignment device proposed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of this invention.

[0064] As used in this invention, the singular forms “a,” “an,” and “the” include plural objects; the term “or” is generally used to mean “and / or”; the term “a number” is generally used to mean “at least one”; and the term “at least two” is generally used to mean “two or more”. Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as “first,” “second,” or “third” may explicitly or implicitly include one or at least two of that feature. Additionally, as used in this invention, “installed,” “connected,” “joined,” and “one element “set” on another element should be interpreted broadly, generally indicating only a connection, coupling, mating, or transmission relationship between the two elements, which can be direct or indirect through an intermediate element. They should not be construed as indicating or implying a spatial positional relationship between the two elements, i.e., one element can be located inside, outside, above, below, or to one side of another element, unless otherwise explicitly stated. For those skilled in the art, the specific meaning of the above terms in the invention can be understood according to the specific circumstances. Furthermore, directional terms such as above, below, up, down, upward, downward, left, right, etc., are used relative to exemplary embodiments as shown in the figures, with upward or up direction pointing towards the top of the corresponding figure, and downward or down direction pointing towards the bottom of the corresponding figure.

[0065] Wafer pre-alignment is a crucial module of the transfer subsystem. The transfer robot retrieves the wafer from the wafer memory, and after being centered and oriented by the wafer pre-alignment equipment, it is lifted onto the worktable and then moved to the alignment station for alignment. This requires that after the wafer is initially positioned by the pre-alignment equipment, the markings on the wafer must be within the alignment field of view. Because wafer markings have high positional accuracy relative to the wafer's geometric features, wafer pre-alignment achieves wafer centering based on the outer circular geometry and wafer orientation based on edge notches or flat edges. The orientation method typically involves providing illumination from top to bottom towards the wafer's edge, using the brightness of the illumination to distinguish and identify notches.

[0066] In wafer processing, certain processes can cause changes in the appearance of notches on the wafer.

[0067] Taking TSV (Through Silicon Via) technology as an example, TSV is a cutting-edge technology that enables interconnection between chips by creating vertical conductions between chips and wafers. It has advantages such as small package size, fast signal transmission, and low power consumption.

[0068] After undergoing various TSV processes, the edges of a standard wafer exhibit the following characteristics: misalignment and non-concentric bonding, edge wear, scribe lines, sputtered metal or residual adhesive on the wafer surface, and wafer warping. Wafer notches manifest as: incomplete notches, damage, filling or covering with metal or adhesive, or the presence of metal traces. This indicates a significant deterioration in the wafer notch morphology.

[0069] Therefore, when the wafer notch morphology changes drastically due to the processing technology, the conventional method of identifying notches by light intensity cannot meet the wafer pre-alignment accuracy requirements.

[0070] Currently, for wafers with drastic changes in notch morphology, an aligner is generally used for wafer exposure. The aligner does not consider the changes in the wafer's notch morphology; it involves direct manual alignment of the markings before exposure. This wafer pre-alignment method suffers from low efficiency, low pre-alignment accuracy, and the inability to achieve automated operation due to the susceptibility of pre-alignment accuracy to human error.

[0071] Based on this, a pre-alignment method and pre-alignment device are proposed. This method is suitable for the pre-alignment of wafers with drastic changes in notch morphology, which helps to improve work efficiency and facilitates automated alignment operations.

[0072] First refer to Figure 1 The structure of the pre-alignment device is described.

[0073] The pre-alignment device includes an information acquisition unit 10, a pre-alignment motion unit 20, an information processing unit, a side light source 30, a bottom light source 40, and a point light source 50.

[0074] The information acquisition unit 10 is used to acquire edge information, scribing groove image information, and edge image information of the wafer;

[0075] When it collects edge information of the wafer, it can calculate the actual center of the wafer, and then calculate the eccentricity by comparing it with the reference center, providing a basis for centering.

[0076] By using the image information of the scribing groove, the actual direction of the scribing groove can be obtained, and then compared with the specified direction of the scribing groove, providing a basis for adjusting the direction of the scribing groove;

[0077] Edge image information is used to match the notch in the template. When the match is successful, the notch position of the wafer is obtained. At this time, the actual direction of the wafer notch can be obtained, and thus orientation can be completed.

[0078] The information acquisition unit 10 includes an acquisition unit 11 and a driving unit 12.

[0079] The acquisition unit 11 is used to acquire edge information, scribing groove image information, and edge image information of the wafer;

[0080] The acquisition unit 11 includes a pre-alignment camera 111 and a pre-alignment lens 112. The alignment camera may include a line scan camera and an area scan camera.

[0081] In other alternative embodiments, the alignment camera may be either an area scan camera or a line scan camera.

[0082] The acquisition unit can be used to acquire images of wafer 60 and obtain corresponding information based on the images. It can obtain edge information of the wafer by comparing the light intensity and darkness in the image, identify notches on the wafer edge by the image, and identify the direction of the scribing groove by the image.

[0083] The acquisition unit 11 can be completed using existing cameras. Its acquisition principle and method are existing technologies and will not be described in detail here.

[0084] In other alternative embodiments, the acquisition unit 11 may also include a laser sensor that can identify the edge contour of the wafer by recognizing abrupt changes in distance from the wafer, and then fit the edge of the wafer to calculate the actual center.

[0085] A point light source 50 is mounted on the pre-alignment lens 112 to provide illumination for the acquisition field of view of the acquisition unit 11. Since the acquisition field of view of the acquisition unit 11 is generally at the millimeter level, point illumination is sufficient for the point light source 50 to meet its illumination requirements. The point light source 50 moves with the pre-alignment lens 112 to provide illumination for the scribing grooves on the upper surface of the wafer from top to bottom, and the acquisition unit 11 acquires image information of the scribing grooves on the upper surface of the wafer located within the illumination area of ​​the point light source 50.

[0086] Please continue to refer to this. Figure 1 As shown, the acquisition unit 11, the side light source 30, the bottom light source 40, and the point light source 50 are all mounted on a bracket. The bracket is driven to move by the drive unit 12, so that the acquisition unit 11, the side light source 30, the bottom light source 40, and the point light source 50 can be driven away from or closer to the pre-alignment motion unit 20.

[0087] In this embodiment, the side light source 30, the bottom light source 40, and the point light source 50 all use LED lights. In other alternative embodiments, existing lighting equipment can be selected for each light source based on actual usage requirements.

[0088] The drive unit 12 can drive each component to move horizontally. Specifically, the drive unit 12 can drive each component to move horizontally in the Y direction via a horizontal Y-axis motor, or it can drive each component to move horizontally in the Y direction via a hydraulic drive structure. The drive unit 12 can select an existing drive structure based on actual usage requirements.

[0089] In other alternative embodiments, the drive unit 12 may also be equipped with an X-direction drive motor to drive each component to move horizontally along the X direction based on usage requirements. The specific drive direction of the drive unit 12 can be flexibly adjusted based on actual usage requirements.

[0090] In this embodiment, the drive unit 12 synchronously drives the acquisition unit 11, the side light source 30, the bottom light source 40, and the point light source 50 to move. In other alternative embodiments, the drive unit 12 may include multiple independent drive motors, with each of the acquisition unit 11, the side light source 30, the bottom light source 40, and the point light source 50 matched with a portion of the drive motors to achieve independent driving of the aforementioned components.

[0091] Please continue to refer to this. Figure 1 As shown, the side light source 30 is located above the bottom light source 40, and the side light source 30 and the bottom light source 40 are horizontally offset. In one embodiment, the bottom light source 40 protrudes more horizontally.

[0092] The side light source 30 provides illumination from the side. The side light source 30 can provide illumination from above at an angle downwards, horizontally, or from below at an angle upwards. In this embodiment, it provides illumination from above at an angle downwards, preferably at a 45° angle. When the edge of the wafer 60 is moved to directly above the bottom light source 40 and continues to move towards the side light source 30, the side light source 30 illuminates downwards to the edge of the wafer 60. Because the side light source 30 illuminates downwards at an angle, the edge of the wafer 60 does not need to move directly below the side light source 30, thus not obstructing the field of view of the acquisition unit 11. When the wafer 60 moves slightly outwards, its edge faces the bottom light source 40, allowing it to provide vertical upward illumination through the bottom light source 40, while also ensuring that the side light source 30 does not obstruct the field of view.

[0093] Of course, in other alternative embodiments, both the side light source 30 and the bottom light source 40 can illuminate the wafer at an angle. By adjusting their illumination directions, they can provide illumination independently without interfering with each other or affecting the information acquisition of the information acquisition unit 10.

[0094] Please continue to refer to this. Figure 1 As shown, the pre-alignment motion unit 20 includes a vertical part 21, a rotating part 22, and a translational part 23.

[0095] The rotating part 22 is disposed on the vertical part 21. The vertical part 21, the rotating part 22, and the translation part 23 can be driven by motors respectively.

[0096] The rotating part 22 has a first adsorption structure (not shown in the figure), such as a P-chuck suction cup. A vacuum groove can be formed on the upper surface of the first adsorption structure to adsorb the wafer onto it. When the rotating part 22 rotates, it drives the first adsorption structure and the wafer adsorbed on it to rotate. The first adsorption structure facilitates wafer transfer via a transfer robot. The transfer method involves the transfer robot actively picking up and placing the wafer. When the robot places the wafer on the first adsorption structure, it can be adsorbed under vacuum. Adsorption of the wafer only requires controlling the vacuum switch on the first adsorption structure.

[0097] Furthermore, a second adsorption structure 231 is provided on the translation part 23. The second adsorption structure is, for example, a C-chuck suction cup. The first adsorption structure passes through the second adsorption structure 231. The first adsorption structure can move up and down with the vertical part 21, so the first adsorption structure can move up and down relative to the second adsorption structure 231. The second adsorption structure 231 can be driven to move horizontally by the translation part 23.

[0098] The first adsorption structure and the second adsorption structure 231, together with the rotating part 22 and the translation part 23, can drive the wafer to rotate and move horizontally. This enables the pre-alignment function that automatically switches between 6-inch, 8-inch, and 12-inch wafer sizes.

[0099] When the wafer needs to rotate to acquire its edge position, it can be adsorbed onto the first adsorption structure. When the wafer needs to be driven to move horizontally for centering, the first adsorption structure releases the vacuum. The vertical part 21 drives the first adsorption structure to lower, making the first adsorption structure lower than the second adsorption structure 231. The wafer is supported on the second adsorption structure 231, and the translation part 23 drives the second adsorption structure 231 to move horizontally, thereby driving the wafer to move horizontally.

[0100] In this embodiment, the translation unit 23 is used to drive the second adsorption structure 231 to move horizontally along the Y direction. In other alternative embodiments, the translation unit 23 can drive the second adsorption structure 231 to move horizontally along both the X and Y directions, and the driving direction of the translation unit 23 can be adaptively adjusted based on its alignment requirements.

[0101] Please continue to refer to this. Figure 1 and Figure 2 As shown, the bottom light source 40 provides illumination to the edge of the wafer from bottom to top. Part of the light source shines upwards through the wafer edge, while another part is blocked by the wafer, resulting in a significant contrast between light and dark at the wafer edge when viewed from top to bottom. At this time, the information acquisition unit 10 acquires an image of the wafer edge from top to bottom, and obtains the edge information by identifying the light intensity at the wafer edge. The actual center of the wafer is then calculated by fitting the edge of the wafer. The bottom light source 40 can identify the wafer edge through a significant contrast between light and dark, and the corresponding actual center is calculated by fitting its edge.

[0102] In scenarios where the wafer notch morphology undergoes drastic changes, such as wafers processed using the TSV process, uneven coating or different coating materials may exist near the wafer notch after resist application, resulting in significant changes in the notch morphology. Therefore, when illuminated by the bottom light source 40, a clear change in brightness and darkness cannot be obtained at the notch edge. In this case, the bottom light source 40, in conjunction with the acquisition unit 11, cannot capture a clear image of the notch from above, thus preventing the proper pre-alignment orientation function from being achieved.

[0103] Therefore, a side light source 30 is added to provide illumination to the edge of the wafer from the side, and the information acquisition unit 10 acquires edge image information of the edge of the upper surface of the wafer 60 within the illumination area of ​​the side light source 30. The side light source 30 is located on the side of the wafer edge, and utilizes the height difference at the wafer notch to extract image features for directional processing. The side light source 30 is installed on the side of the wafer, with an optimal illumination angle of 45°, so that the information acquisition unit 10 can clearly capture the image of the notch.

[0104] The information processing unit is used to process edge information and calculate the eccentricity of the wafer, process the scriber image information to obtain the actual direction of the scriber on the wafer, and process the edge image information to obtain the notch position of the wafer; then, in conjunction with the pre-alignment motion unit 20, it drives the wafer to move to compensate for the eccentricity and adjusts the direction of the scriber on the wafer to the specified direction.

[0105] Information processing units typically include at least one processor, which can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), off-the-shelf programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0106] The at least one processor can communicate with multiple peripheral devices via a bus subsystem. These peripheral devices may include storage systems, user interface input devices, user interface output devices, and network interfaces.

[0107] A network interface provides an interface to external networks and / or other devices. Network interfaces include one or more interfaces known in the art, such as LAN, WLAN, Bluetooth, other wired and wireless interfaces, etc.

[0108] User interface input devices may include keyboards, clicking devices such as mice, trackballs, touchpads or graphics tablets, scanners, foot pedals, joysticks, touchscreens embedded in displays, audio input devices such as voice recognition systems, microphones, and other types of input devices. Generally, the term "input device" is intended to encompass a variety of conventional and proprietary devices and methods for inputting information into a controller.

[0109] User interface output devices may include display subsystems, printers, fax machines, or non-visual displays such as audio output devices. Display subsystems may be flat panel devices, such as liquid crystal displays (LCDs), light-emitting diode (LED) displays, touchscreen displays, etc. Display subsystems may also provide non-visual displays, such as via audio output devices. Generally, the term "output device" is intended to encompass a variety of conventional and proprietary devices and methods for outputting information from an information processing unit to a user.

[0110] The storage system can store the basic program designs and data structures that implement the various functions of the present invention. For example, as described herein, databases and modules that implement the functions of the methods of the present invention can be stored in the storage system. These software modules are typically executed by a processor. In a distributed environment, software modules can be stored on multiple computer systems and executed by the processors of multiple computer systems. The storage system typically includes a memory subsystem and a file storage system. The memory subsystem typically includes multiple memories, including main random access memory (RAM) for storing instructions and data during program execution and read-only memory (ROM) in which fixed instructions are stored. The file storage subsystem provides permanent (non-volatile) storage for program and data files. The file storage system 60 may include hard disk drives and associated removable media, disc drives (CDs), optical drives, DVDs, solid-state storage, and / or other removable media. One or more of these drives may be located at a remote location on another connected computer at another point connected to the information processing unit. Modules that implement the functions of the present invention can be stored by the file storage system.

[0111] The bus subsystem provides components that enable the various parts and subsystems of the information processing unit to communicate with each other as intended. The various subsystems and parts of the information processing unit do not need to be in the same physical location, but can be distributed across various locations within a distributed network. The bus subsystem can be a single bus, or multiple buses can be configured based on requirements.

[0112] The information processing unit described above is intended only as an example to illustrate just one embodiment of the invention. Due to the ever-changing nature of computers and networks, the information processing unit may also have a configuration that differs from the information processing unit depicted above in other alternative embodiments, which will not be elaborated here.

[0113] When the information processing unit processes image information and calculates the wafer's eccentricity, the edge information can be an image. The information processing unit can then calculate gradient information from the image to identify the wafer's edge contour and calculate its actual center. Alternatively, the edge information can be the distance from the wafer's upper surface. When the wafer edge is detected, the detected distance changes abruptly due to the wafer's height abruptly, and this abrupt change in distance is used to detect the wafer edge.

[0114] When the information processing unit processes the scribe line image information to obtain the actual direction of the scribe line on the wafer, the scribe line image information is an image of the scribe line on the wafer surface captured by the camera. The actual direction of the scribe line is then calculated. Based on the camera's field of view, one scribe line can be captured in the image at a time. Image integration is performed along a straight line trajectory in a small region of the scribe line image information, and the actual direction of the scribe line is obtained based on the peak value of the image integral. This integration can be performed, for example, by integrating over pixels or gradients. Mathematical integration has a low-frequency filtering effect. Compared to mathematical differentiation, mathematical integration can effectively suppress high-frequency signals in the image, so that interference information will not significantly affect the recognition result. This effectively solves the uncertainty caused by the reliance on high-frequency signals (noise edges) in the Hough transform previously used.

[0115] Please refer to Figure 4 and Figure 5 As shown, Figure 4 The image in the middle represents the integral data for identifying the direction of one of the cross-shaped grooves. Figure 5 Integral data plot for identifying the direction of another scribed groove.

[0116] The approximate direction of the scribed groove can be identified by image acquisition, and then integration is performed on a straight trajectory perpendicular to the scribed groove to obtain the precise direction.

[0117] Figure 4 and Figure 5 In the diagram, the horizontal axis represents the subdivision by angle, which is applied within a range approximately perpendicular to the scribed groove to precisely determine its direction. This subdivision marks the direction of the straight line trajectory, while the vertical axis represents the pixel accumulation value. Since the area within the scribed groove is darker in color, its gradient or pixel depth is also darker. For example, if the integration region contains multiple rows of pixels, each row perpendicular to the integration trajectory, and if each row is parallel to the scribed groove, almost all pixels in each row will be located within the groove, and the pixel summation after integration along the direction perpendicular to the groove will reach its peak. If the rows are not parallel to the groove, a portion of the pixels in each row will fall outside the groove; therefore, integration along the trajectory perpendicular to each row will not reach its peak.

[0118] like Figure 4As shown, a pixel peak was obtained at a position where the angle subdivision is slightly less than 400. The straight line trajectory corresponding to this peak is perpendicular to one of the scribed grooves. Therefore, the direction of the scribed groove can be determined. Figure 5 As shown, a pixel peak was obtained at a position where the angle subdivision is slightly greater than 400. The straight line trajectory corresponding to this peak is perpendicular to one of the scribed grooves. Therefore, the direction of the scribed groove can be determined.

[0119] After obtaining the direction of the scribing groove, it can be compared with the specified direction. If the error between the two is greater than the threshold, the rotation direction required for the wafer to rotate to the specified direction can be calculated. The wafer can then be rotated to make the scribing groove rotate to the specified direction.

[0120] When the information processing unit processes edge image information to obtain the wafer notch location, it selects a template image from the edge dataset of the template image that matches the notch of the wafer of this specification, and then matches the edge image information with the template image. It searches for the gradient and direction of the image in the edge image information, and uses non-maximum suppression to extract edge information. This filters out pixels with insufficient gradients. A double threshold algorithm is used to detect and connect edges, thus limiting the image to a certain grayscale range that represents the true notch information.

[0121] During image matching, image gradient information of edge image information is calculated, and the gradient information is layered.

[0122] The amount of gradient information contained in each layer increases sequentially;

[0123] The layers are arranged in ascending order of the amount of gradient information they contain, and the gradient information of each layer is matched sequentially with the gradient information of the template. This is similar to pyramid sampling of edge image information: a coarse match is performed at the top of the pyramid to locate a position value, and then fine matching is performed layer by layer downwards. If the gradient information of a current layer matches the template, the matching of the gradient information of the next layer is performed; if the gradient information of a current layer does not match the template, edge image information at other locations on the wafer edge is re-acquired. The matching calculation method can be, for example, calculating the average of the dot product of the gradient vectors of corresponding edge points in the template and the edge image information.

[0124] Combination Figures 1 to 3 The pre-alignment device, and combined with Figure 6 As shown, the alignment process is as follows:

[0125] After pre-alignment begins, the transfer robot transports the wafer to the first adsorption structure. The vertical part 21 moves to the pre-alignment station, the first adsorption structure adsorbs the wafer, the bottom light source 40 is turned on, and the rotating part 22 rotates the wafer at a constant speed for one revolution. The upper control information acquisition unit 10 begins image acquisition through the area array camera, capturing the wafer edge, and the information processing unit calculates the wafer eccentricity. Then, the vertical part 21 lowers to the junction position with the translation part 23. The first adsorption structure (P-chuck) releases the vacuum, and the second adsorption structure 231 (C-chuck) opens the vacuum to adsorb the wafer. After the vertical part 21 drives the first adsorption structure to lower to the junction low position, the translation part 23 moves horizontally. The translation part 23 drives the second adsorption structure 231 (C-chuck) to move horizontally, thereby compensating for the wafer eccentricity. After compensation is completed, the vertical part 21 rises to the junction position of the translation part 23, the second adsorption structure 231 (C-chuck) releases the vacuum to release the wafer, the first adsorption structure (P-chuck) opens the vacuum to adsorb the wafer, the vertical part 21 rises to the pre-alignment position, the rotating part 22 rotates the wafer one revolution, the information acquisition unit 10 collects information, and the information processing unit calculates the residual deviation of the eccentricity.

[0126] If the residual meets the error window index requirements, the drive unit 12 drives the acquisition unit 11 to move towards the pre-alignment motion unit 20, so that the acquisition unit 11 moves to the inner edge of the wafer. At the same time, the upper control information acquisition unit 10 takes pictures of the scribing groove inside the upper surface of the wafer through the line scan camera, calculates the actual direction of the scribing groove, and calculates the required rotation angle of the wafer based on the actual direction and the set direction. Then, the rotation unit 22 rotates the wafer to compensate for the angle, so that the scribing groove rotates to the specified direction. In one embodiment, the specified direction is the direction in which the scribing groove is horizontal and vertical relative to the information acquisition unit 10. As shown in the figure, the scribing groove is generally in the shape of a cross, that is, the specified direction of the scribing groove adjustment is that the horizontal groove is parallel to the information acquisition unit 10, and the vertical groove is perpendicular to the information acquisition unit 10.

[0127] like Figure 3 As shown. Then, the drive unit 12 drives the acquisition unit 11 to move away from the pre-alignment motion unit 20, so that the acquisition unit 11 moves to the edge of the wafer. The side light source 30 is turned on, the rotating unit 22 drives the wafer to rotate, and the acquisition unit 11 acquires the edge pattern information of the wafer, performs image matching, and identifies the direction of the notch.

[0128] During edge image acquisition at the wafer edge, since the wafer edge is circular and the scribe lines have a grid structure, the direction of the scribe lines is known, and the relative position of the wafer notch to the scribe lines can be determined using a template. Therefore, the target location of the notch on the wafer's outer perimeter can be roughly calculated. A geometric template matching algorithm is then used to calculate the angle at which the notch exists on the wafer, thus completing the orientation function. There are four target locations for the notch on the wafer's outer perimeter; therefore, image acquisition at a maximum of four target locations is sufficient to identify the notch's location.

[0129] First, the first target position on the edge of the wafer is rotated into the field of view of the acquisition unit 11 to acquire edge image information. If no match is found, the wafer is rotated 90° to continue acquiring and matching. If the match is unsuccessful, it is rotated 90° to 180° relative to the initial position, and so on. If the match is unsuccessful, it is rotated 90° to 270° relative to the initial position, until all target positions are acquired.

[0130] If no gap is found at any of the above target locations, edge image information can be collected and matched within a range of ±10mrad around these target locations to resolve the asymmetry between the gap and the scribed groove.

[0131] By extension, as long as the pre-alignment component has a vertical part 21, a rotating part 22, a translation part 23 and an information acquisition unit, and has a side light source 30 and a bottom light source 40, pre-alignment of a wafer whose notch morphology has changed drastically can be achieved.

[0132] The present invention also provides a pre-alignment method, comprising the following steps;

[0133] S1: Collect edge information of the wafer, obtain the eccentricity of the actual center relative to the reference center, and adjust the wafer position to compensate for the wafer eccentricity.

[0134] Specifically, the bottom light source 40 provides illumination to the edge of the wafer from bottom to top, and the information acquisition unit 10 detects the light intensity at the wafer edge from above, extracts the edge information, and the information processing unit calculates the actual center and thus the eccentricity. The acquisition and information processing processes have been described in detail above and will not be repeated here.

[0135] S2: Acquire image information of the scribing grooves on the upper surface of the wafer, obtain the actual direction of the scribing grooves, and rotate the wafer to adjust the direction of the scribing grooves to the specified direction;

[0136] During the extraction process, a point light source 50 can be used to provide local illumination to extract the image information of a scribed groove corresponding to a crosshair groove. Image integration is then performed along the straight line trajectory of this scribed groove image information, and the actual direction of the scribed groove is obtained based on the peak value of the image integral. This integration can be performed on pixels or gradients, for example. After obtaining the direction of the scribed groove, it can be compared with a specified direction. If the error between the two is greater than a threshold, the required rotation direction of the wafer to rotate the scribed groove to the specified direction is calculated. This can then be adjusted by rotating the wafer to ensure the scribed groove rotates to the specified direction.

[0137] S3: Acquire edge image information at the edge of the upper surface of the wafer, match the edge image information with the notch of the template, and obtain the notch position of the wafer to complete the orientation.

[0138] Lateral illumination is provided at the edge of the wafer. Preferably, the lateral light source illuminates the edge of the wafer from the upper side at an angle downwards. The wafer is rotated so that the edge of the wafer passes through the illumination area in sequence, and the edge image information of the edge of the upper surface of the wafer located within the illumination area is acquired.

[0139] Furthermore, since the direction of the scribe groove is known, the grid structure of the scribe groove, and the relative positional relationship between the direction of the scribe groove and the notch can be obtained through the template.

[0140] Therefore, four target locations where the notch may exist can be obtained at the edge of the wafer, with each target location spaced 90° apart from the center angle.

[0141] Therefore, edge image information only needs to be acquired at the four target locations mentioned above. One target location is used as the acquisition target for edge image information acquisition. If matching fails, the wafer is rotated sequentially so that the next target location passes through the information acquisition unit 10.

[0142] In summary, edge image information acquisition can be categorized into the following steps:

[0143] S3-1: Using the position of the scribing groove relative to the notch in the template as a reference, obtain several target locations where the wafer edge may have a notch. Determine one of these target locations as the initial acquisition position, ensuring that the initial acquisition position is within the illumination area. Since the direction of the scribing groove is known at this point, and the relative positional relationship between the wafer notch and the scribing groove is known through the template, the target locations where the notch exists on the outer periphery of the wafer can be roughly calculated. Because the existing wafer edge is circular and the scribing groove has a grid structure, based on the existing wafer structure and the relative positional relationship between the notch and the scribing groove acquired in the template, it can be known that there are four target locations where the notch exists on the outer periphery of the wafer. Therefore, at most, image acquisition is needed at four target locations to identify the location of the notch.

[0144] S3-2: Perform edge image information acquisition and image matching at the initial acquisition position. If the matching is successful, the wafer orientation is completed; if the matching is unsuccessful, proceed to step S3-3.

[0145] S3-3: Rotate the wafer to place the next target position within the illumination area, and acquire edge image information of the target position and perform image matching;

[0146] S3-4: If the matching is successful, the wafer orientation is complete; if the matching is unsuccessful, proceed to step S3-3.

[0147] Furthermore, during the template matching process, image gradient information of edge image information is calculated, and the gradient information is layered.

[0148] The amount of gradient information contained in each layer increases sequentially;

[0149] The layers are arranged in ascending order of the amount of gradient information they contain, and the gradient information of each layer is matched sequentially with the gradient information of the template. This is similar to pyramid sampling of edge image information: a coarse match is performed at the top of the pyramid to locate a position value, and then fine matching is performed layer by layer downwards. If the gradient information of a current layer matches the template, the matching of the gradient information of the next layer is performed; if the gradient information of a current layer does not match the template, edge image information at other locations on the wafer edge is re-acquired. The matching calculation method can be, for example, calculating the average of the dot product of the gradient vectors of corresponding edge points in the template and the edge image information.

[0150] The aforementioned orientation method acquires edge information of the wafer to fit the wafer's edge, obtaining the actual center position and thus the eccentricity, thereby achieving wafer centering. It also acquires information about the scribing grooves on the wafer surface to obtain the actual direction of the grooves and rotates them to a specified direction to adjust the wafer's initial pose. Furthermore, based on the relative positional relationship between the scribing grooves and notches in the actual template, several target locations where notches may exist at the wafer edge can be preliminarily determined, facilitating the acquisition of wafer notch locations. Then, illumination is provided to the wafer edge from top to bottom to acquire edge image information within the illuminated area. Utilizing the height difference characteristic at the wafer notch edge, image features are extracted and matched with the template to obtain the wafer notch location, achieving wafer orientation. This alignment method is suitable for the pre-alignment of wafers with drastic changes in notch morphology. It improves the pre-alignment accuracy of wafers with drastic changes in notch morphology, increases the pre-alignment orientation pass rate of wafers, reduces orientation time, and helps improve work efficiency. This alignment method does not require manual intervention, which helps to realize automated alignment operations. It also eliminates human interference factors during the alignment process, solving the problems of low pre-alignment efficiency, low pre-alignment accuracy, and inability to realize automated operations for wafers with drastic changes in notch morphology in the past.

[0151] The pre-alignment method has been described in detail in the above description of the pre-alignment device structure, and will not be repeated here.

[0152] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0153] The above description is merely a description of preferred embodiments of the invention and is not intended to limit the scope of the invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A pre-alignment method, characterized in that, Includes the following steps; S1: Provide illumination to the edge of the wafer from bottom to top, detect the light intensity at the edge of the wafer from above the wafer, extract edge information, collect the edge information of the wafer to obtain the eccentricity, and adjust the wafer position to compensate for the wafer eccentricity; S2: Acquire image information of the scribing grooves on the upper surface of the wafer, obtain the actual direction of the scribing grooves, and rotate the wafer to adjust the direction of the scribing grooves to the specified direction; S3: Provide lateral illumination from above and downwards to the edge of the wafer, acquire edge image information of the edge of the upper surface of the wafer located within the illumination area, and match the edge image information with the notch of the template to obtain the notch position of the wafer and complete the orientation; In step S3, the image gradient information of the edge image information is calculated, and the gradient information is layered. The amount of gradient information contained in each layer increases sequentially; Arrange the layers in ascending order of the amount of gradient information they contain, and match the gradient information of each layer with the gradient information of the template in turn; If the gradient information of this layer matches the template, then proceed to the next layer for gradient information matching; If the gradient information of this layer does not match the template, then edge image information at other locations on the wafer edge will be re-acquired.

2. The pre-alignment method as described in claim 1, characterized in that, In step S3, the wafer is rotated so that the edge of the wafer passes through the illumination area in sequence, and the edge image information of the edge of the upper surface of the wafer located within the illumination area is acquired.

3. The pre-alignment method as described in claim 1, characterized in that, In step S3, edge image information acquisition includes the following steps: S3-1: Using the relative positional relationship between the scribe groove and the notch in the template as a reference, obtain several target positions with notches on the wafer edge, determine one of the target positions as the initial acquisition position, and make the initial acquisition position located within the illumination area; S3-2: Perform edge image information acquisition and image matching at the initial acquisition position. If the matching is successful, the wafer orientation is completed; if the matching is unsuccessful, proceed to step S3-3. S3-3: Rotate the wafer to place the next target position within the illumination area, and acquire edge image information of the target position and perform image matching; S3-4: If the matching is successful, the wafer orientation is complete; if the matching is unsuccessful, proceed to step S3-3.

4. The pre-alignment method as described in claim 3, characterized in that, The center angle between each target position is 90°.

5. The pre-alignment method as described in claim 1, characterized in that, The specified direction is the direction in which the scribed groove is horizontal and vertical relative to the information acquisition unit.

6. The pre-alignment method as described in claim 1, characterized in that, In step S2, the image information of the scribed groove corresponding to a cross-shaped scribed groove is extracted, and the image integral along the straight line trajectory in the scribed groove image information is performed. The actual direction of the scribed groove is obtained based on the peak value of the image integral.

7. A pre-alignment device, characterized in that, It includes an information acquisition unit, a pre-alignment motion unit, an information processing unit, a side light source, and a bottom light source; The information acquisition unit is used to acquire edge information, scribing groove image information, and edge image information of the wafer; The information processing unit is used to process edge information and calculate the eccentricity of the wafer, to process the scribing image information to obtain the actual direction of the scribing groove of the wafer, and to process the edge image information to obtain the notch position of the wafer. The pre-alignment motion unit is used to drive the wafer to move in order to compensate for the eccentricity and adjust the direction of the scribe grooves on the wafer to the specified direction. The side light source is used to provide downward-sloping illumination to the edge of the wafer, and the information acquisition unit acquires edge image information of the edge of the upper surface of the wafer located within the illumination area of ​​the side light source; The bottom light source is used to provide illumination to the edge of the wafer from bottom to top, and the edge information of the wafer is obtained by identifying the light intensity at the edge of the wafer from top to bottom through the information acquisition unit.

8. The pre-alignment device as claimed in claim 7, characterized in that, The pre-alignment motion unit includes a vertical part, a rotating part, and a translational part; The vertical section is used to drive the wafer to make vertical movements; The rotating part is used to drive the wafer to rotate along an axis perpendicular to its upper surface; The translation section is used to drive the wafer to move horizontally.

9. The pre-alignment device as claimed in claim 7, characterized in that, The pre-alignment device also includes a point light source, which is used to provide illumination for the scribing grooves on the upper surface of the wafer from top to bottom, and to acquire image information of the scribing grooves on the upper surface of the wafer located within the illumination area of ​​the point light source through an information acquisition unit.

10. The pre-alignment device according to any one of claims 7 to 9, characterized in that, The information acquisition unit includes an acquisition unit and a driving unit; The acquisition unit is used to acquire edge information, scribing groove image information, and edge image information of the wafer; The drive unit is used to drive the acquisition unit to move; And / or, the driving unit is used to drive the lateral light source to move; And / or, when the pre-alignment device includes a bottom light source, the driving unit is used to drive the bottom light source to move; And / or, when the pre-alignment device includes a point light source, the driving unit is used to drive the point light source to move.

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