Wafer transmission method, wafer transmission equipment and computer storage medium

Abstract

The invention provides a wafer transmission method, wafer transmission equipment and a computer storage medium. The method comprises the following steps: calibrating sensor coordinates and wafer circle center coordinates according to trigger coordinates of the tail end of a manipulator; a tool coordinate system is established at the circle center of the wafer based on the circle center coordinates of the wafer, and the target position of the wafer feeding table is demonstrated; controlling a manipulator to carry the wafer to be rectified according to the target position, and collecting transmission trigger data in the carrying process; the coordinates of the circle center of the wafer to be rectified are calculated through the sensor coordinates and the transmission triggering data; based on the coordinates of the circle center of the wafer to be rectified and the target position, the angles of all joints of the mechanical arm are adjusted, and position rectification of the circle center of the wafer is completed. By means of the wafer transmission method, the wafer circle center position dynamic deviation correction which is easy to operate and higher in precision is achieved, high-precision deviation correction of the wafer circle center position is completed in the wafer carrying process of a mechanical arm, and the wafer carrying accuracy is improved.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor wafer processing, and particularly to a wafer transfer method, a wafer transfer device, and a computer storage medium. Background Art

[0002] During the transfer and processing of wafers, various factors may cause the position of the wafer to shift. For example, the position is inaccurate when the manipulator grabs the wafer, vibration interference during equipment operation, or the influence of other environmental conditions. If these deviations are not corrected, the wafer may not be aligned with the predetermined position in the subsequent processing stage, resulting in a decrease in process accuracy, and may even cause processing errors, material waste, or damage to product performance, seriously affecting production efficiency and yield. In addition, when transferring between multiple devices, this position deviation may accumulate with the increase in processes, further amplifying the error and bringing quality risks to the entire manufacturing process. Therefore, achieving dynamic correction of the center position of the wafer is a prerequisite for improving product quality and production efficiency. The existing methods for correcting the center position of the wafer mainly include calculating the offset of the actual wafer relative to the reference wafer through the pre-calibrated sensor coordinates, or obtaining the offset of the actual wafer relative to the reference wafer in the finger and perpendicular finger directions by comparing the trigger data of the actual wafer and the reference wafer, and then adjusting the center position through the relative offset.

[0003] However, the existing methods for dynamically correcting the center position of the wafer have the following problems:

[0004] 1. The calibration operation is complex, has poor practicability, and it is difficult to guarantee the calibration accuracy. Before calibrating the sensor position, it is necessary to first calibrate the coordinates of the center of the manipulator finger relative to the end coordinate system of the manipulator, that is, it is necessary to first calibrate the tool coordinate system of the manipulator, and it is necessary to first measure the offset of the wafer center relative to the manipulator finger center, or it is necessary to first eliminate this offset to obtain a reference wafer, and then use the manipulator to carry this reference wafer to trigger the sensor and calculate the sensor coordinates. The above calibration process is relatively cumbersome and the operation is complex. And when calibrating the sensor position, the manipulator triggers the sensor by linear motion along a fixed angle, and the calibration result is affected by the motion error of the manipulator or the position error of the reference wafer.

[0005] 2. It is difficult to guarantee the correction accuracy. Correcting through the relative offset of the actual wafer and the reference wafer requires the initial tool coordinate system of the manipulator to be accurate to ensure a high correction accuracy, or a manipulator with a higher degree of freedom to achieve a translational correction motion with an unchanged end attitude.

[0006] Therefore, a method for dynamically correcting the center position of the wafer with simple operation, good practicability, and high accuracy is needed. Summary of the Invention

[0007] The object of the embodiments of the present application is to propose a wafer transfer method, a wafer transfer device, and a computer storage medium, which can solve the problems in the prior art such as complex calibration operation, poor calibration accuracy, poor practicability, and poor alignment accuracy. It enables the manipulator to complete high-precision alignment of the center position of the wafer during the process of transporting the wafer, and provides a method and system for correctly and efficiently verifying the feasibility and alignment accuracy of the alignment solution.

[0008] To solve the above technical problems, the present application proposes a wafer transfer method, which includes:

[0009] Controlling the manipulator to transport the wafer through the sensor area and collecting the trigger coordinates at the end of the manipulator;

[0010] Calibrating the sensor coordinates and the center coordinates of the wafer according to the trigger coordinates at the end of the manipulator;

[0011] Based on the center coordinates of the wafer, establishing a tool coordinate system at the center of the wafer and teaching the target position of the wafer loading table;

[0012] Controlling the manipulator to transport the wafer to be aligned according to the target position, and collecting the transmission trigger data during the transportation process;

[0013] Calculating the coordinates of the center of the wafer to be aligned by using the sensor coordinates and the transmission trigger data;

[0014] Based on the coordinates of the center of the wafer to be aligned and the target position, adjusting the joint angles of the manipulator to complete the position alignment of the center of the wafer.

[0015] Among them, the controlling the manipulator to transport the wafer through the sensor area and collecting the trigger coordinates at the end of the manipulator includes:

[0016] Determining the motion range and sampling trajectory of the manipulator;

[0017] Controlling the manipulator to transport the wafer through the sensor area according to the motion range and the sampling trajectory, and collecting the trigger coordinates at the end of the manipulator.

[0018] Among them, the calibrating the sensor coordinates and the center coordinates of the wafer according to the trigger coordinates at the end of the manipulator includes:

[0019] Establishing a calibration error model;

[0020] Using the trigger coordinates at the end of the manipulator, by minimizing the calibration error model, determine the coordinates of the sensor in the base coordinate system of the manipulator and the coordinates of the center of the wafer in the coordinate system at the end of the manipulator.

[0021] Among them, establishing a tool coordinate system at the center of the wafer based on the coordinates of the center of the wafer, and teaching the target position of the wafer loading table includes:

[0022] Establish the reference tool coordinate system of the manipulator at the center of the wafer based on the coordinates of the center of the wafer;

[0023] Under the reference tool coordinate system of the manipulator, teach the target position of the wafer loading table.

[0024] Among them, controlling the manipulator to carry the wafer to be corrected according to the target position, and collecting the transmission trigger data during the handling process includes:

[0025] Based on the target position and the tool coordinate system, calculate the first transmission joint coordinates of the manipulator;

[0026] Control the manipulator to carry the wafer to be corrected according to the first transmission joint coordinates until the transmission trigger data is generated and collected.

[0027] Among them, using the sensor coordinates and the transmission trigger data to calculate the coordinates of the center of the wafer to be corrected includes:

[0028] Establish a transmission error model;

[0029] Using the sensor coordinates and the transmission trigger data, by minimizing the transmission error model, calculate the coordinates of the center of the wafer to be corrected;

[0030] Among them, based on the coordinates of the center of the wafer to be corrected and the target position, adjusting the joint angles of the manipulator to complete the position correction of the center of the wafer includes:

[0031] Based on the coordinates of the center of the wafer to be corrected, establish the real-time tool coordinate system of the manipulator at the center of the wafer to be corrected;

[0032] Under the real-time tool coordinate system, based on the target position, calculate the second transmission joint coordinates of the manipulator and complete the position correction of the center of the wafer.

[0033] Among them, the wafer transmission method further includes:

[0034] Record the reference center coordinates of the wafer through a CCD camera;

[0035] Control the manipulator to carry the wafer to be corrected according to the target position, and collect the transmission trigger data during the carrying process;

[0036] Utilize the sensor coordinates and the transmission trigger data to calculate the coordinates of the center of the wafer to be corrected;

[0037] Based on the coordinates of the center of the wafer to be corrected and the reference center coordinates, determine whether the calculated offset value of the wafer to be corrected exceeds the designed correction range;

[0038] If not, based on the coordinates of the center of the wafer to be corrected and the target position, adjust the joint angles of the manipulator to complete the correction of the center position of the wafer;

[0039] Record the center coordinates of the wafer after correction through a CCD camera;

[0040] Generate a random offset for the wafer and perform repeated correction verification.

[0041] To solve the above technical problems, the present application also proposes a wafer transfer device, which includes a memory and a processor coupled to the memory; wherein, the memory is used to store program data, and the processor is used to execute the program data to implement the wafer transfer method as described above.

[0042] To solve the above technical problems, the present application also proposes a computer storage medium, which is used to store program data, and when the program data is executed by a computer, it is used to implement the above wafer transfer method.

[0043] Compared with the prior art, the embodiments of the present application mainly have the following beneficial effects:

[0044] The present application provides a wafer transfer method, a wafer transfer device, and a computer storage medium. By proposing a new dynamic correction method for the center position of the wafer, it has the following beneficial effects:

[0045] 1. When calibrating the sensor coordinates, there is no need to pre-calibrate the tool coordinate system of the manipulator, nor to calculate the sensor coordinates using a reference wafer with a known offset or a reference wafer with an offset of zero, nor to ensure that the trigger movement of the manipulator is a straight line. And by performing multi-angle trigger sampling on the sensor area, the calibration accuracy is guaranteed.

[0046] 2. Through a simple tool calibration method, the teaching accuracy of the pick-and-place target position of the wafer is improved, so that the manipulator can accurately carry the wafer to be detected in place.

[0047] 3. High rectification accuracy. During the process of transporting the wafer, high-precision dynamic rectification of the center position of the wafer is achieved by switching the real-time tool coordinate system for the manipulator, avoiding the use of the theoretical tool coordinate system and considering the relative offset between the actual wafer and the reference wafer for rectification. Brief Description of the Drawings

[0048] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0049] Among them:

[0050] Figure 1 is a schematic flowchart of the first embodiment of the wafer transfer method provided by the present application;

[0051] Figure 2 is a schematic flowchart of an implementation manner of step S100 of the present application;

[0052] Figure 3 is a schematic diagram of an embodiment of the sampling process provided by the present application;

[0053] Figure 4 is a schematic flowchart of an implementation manner of step S110 of the present application;

[0054] Figure 5 is a schematic diagram of an embodiment of the sensor trigger provided by the present application;

[0055] Figure 6 is a schematic flowchart of an implementation manner of step S120 of the present application;

[0056] Figure 7 is a schematic flowchart of an implementation manner of step S130 of the present application;

[0057] Figure 8 is a schematic flowchart of an implementation manner of step S140 of the present application;

[0058] Figure 9 is a schematic flowchart of an implementation manner of step S150 of the present application;

[0059] Figure 10 is a schematic flowchart of the second implementation manner of the wafer transfer method provided by the present application;

[0060] Figure 11 is a schematic flowchart of an implementation manner of step S290 of the present application;

[0061] Figure 12It is a schematic structural diagram of an embodiment of the wafer transfer device provided by the present application;

[0062] Figure 13 It is a schematic structural diagram of an embodiment of the computer storage medium provided by the present application. Detailed implementation manners

[0063] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0064] The terms "first", "second", "third", "fourth", etc. (if any) in the specification, claims and drawings of the present application are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described here can be implemented in an order other than those illustrated or described here. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily need to be limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products or devices.

[0065] In order to enable those skilled in the art to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings.

[0066] Please refer to Figure 1 , Figure 1 It is a schematic flowchart of the first implementation manner of the wafer transfer method provided by the present application. The wafer transfer method provided by the present application includes the following steps:

[0067] S100, control the manipulator to carry the wafer through the sensor area and collect the trigger coordinates at the end of the manipulator.

[0068] Please further refer to Figure 2 , Figure 2 It is a schematic flowchart of an implementation manner of step S100 of the present application. As Figure 2 , step S100 further includes the following sub-steps:

[0069] S101, determine the movement range and sampling trajectory of the manipulator.

[0070] According to the relative position relationship among the manipulator, the vacuum chamber, and the sensor, without collision interference, determine the motion range and sampling trajectory of the manipulator.

[0071] When the space of the vacuum chamber is limited, the motion range of the manipulator carrying the wafer to trigger the sensor is also very small. To overcome the sampling difficulty and improve the accuracy and reliability of the calibration calculation, the present application optimizes the sampling strategy. Without collision interference, trigger in different regions according to different trigger angles to collect as much trigger data of the wafer as possible. For details, please refer to Figure 3 , Figure 3 is a schematic diagram of an embodiment of the sampling process provided by the present application.

[0072] As Figure 3 shown, within the path range of the manipulator for picking and placing the wafer, the space where the manipulator can extend and retract is relatively large, and two sensors can be triggered simultaneously and four trigger signals can be generated. In some regions, due to limited space, the space where the manipulator can extend and retract is small, and only the front part of the wafer can trigger the sensor. At this time, there may be only trigger signals of a single sensor, and only one or two trigger signals can be generated. The front and back parts of the wafer are distinguished according to the position of the wafer on the finger.

[0073] It can be understood that when the manipulator corrects the position of the wafer center during the process of transporting the wafer, it means eliminating the offset of the wafer center position on the horizontal plane. Therefore, only the horizontal plane is discussed here.

[0074] S102, control the manipulator to transport the wafer through the sensor area according to the motion range and the sampling trajectory, and collect the trigger coordinates at the end of the manipulator.

[0075] In the embodiment of the present application, during the process of the manipulator transporting the wafer, the wafer sequentially blocks and leaves two laser sensors. When the wafer enters the sensor detection area and blocks the laser, the sensor outputs a high-level signal. When the wafer leaves, the signal returns to the low level. When the edge of the wafer contacts the laser of the laser sensor, a trigger signal is generated. The high-speed input circuit of the manipulator driver captures this signal jump in real time and immediately latches the encoder positions of each motor shaft of the current manipulator. Considering the encoder resolution, the rotation direction of the motor, the reduction ratio, and the coupling relationship of each joint, the coordinates of each joint of the manipulator are calculated, and the end coordinates of the manipulator are obtained through the forward kinematics. This is a process of data acquisition. Change the trigger angle of the manipulator carrying the wafer passing through the sensor, trigger the sensor multiple times within the motion range of the manipulator carrying the wafer and collect data, and obtain multiple sets of calibration trigger data including the end coordinates of the manipulator.

[0076] It should be noted that affected by the transmission structure characteristics of the wafer transfer manipulator, when the manipulator carries the wafer through the sensor at the same trigger angle, the sensor is triggered in the states of the extended arm and the retracted arm, and the coordinates of the manipulator obtained by latching are usually different, and the calibrated sensor coordinates are also inconsistent. Therefore, when calibrating the sensor and actual deviation correction, the trigger data of the wafer should be collected in the same state of the manipulator.

[0077] S110. Calibrate the coordinates of the sensor and the coordinates of the center of the wafer according to the trigger coordinates at the end of the manipulator.

[0078] Please further refer to Figure 4 , Figure 4 , which is a schematic flowchart of an embodiment of step S110 of this application. As Figure 4 , step S110 further includes the following sub-steps:

[0079] S111. Establish a calibration error model.

[0080] At the sampling stage, the trigger coordinates at the end of the manipulator are collected. The end position is recorded as (Xe(i), Ye(i), 0), and the attitude angle is recorded as (0, 0, Ce(i)). Assume that the coordinates of the center of the wafer relative to the end coordinate system of the manipulator are (tx, ty). Using the trigger coordinates at the end of the manipulator, according to coordinate transformation, the coordinates of the center of the wafer relative to the base coordinate system of the manipulator when triggering the sensor are (Xt(i), Yt(i)), satisfying:

[0081] Xt(i) = Xe(i) + txcos(Ce(i)) - tysin(Ce(i))

[0082] Yt(i) = Ye(i) + txsin(Ce(i)) + tycos(Ce(i))

[0083] Assume that the coordinates of two laser sensors in the base coordinate system of the manipulator are (Xs1, Ys1) and (Xs2, Ys2) respectively, and the radius of the wafer is Rw. From the geometric characteristics of the wafer, it can be obtained that the distance between the sensor and the center of the wafer when triggered is equal to the wafer radius:

[0084]

[0085] Among them, (Xt(i), Yt(i)) represents the coordinate value of the center of the wafer when the wafer triggers sensor 1. Similarly, (Xt(j), Yt(j)) represents the coordinate value of the center of the wafer when the wafer triggers sensor 2.

[0086] Using the multiple trigger data collected at the sampling stage, the calibration error model can be obtained:

[0087]

[0088] Among them, n represents the total number of times the trigger sensor 1 is triggered, and i represents different triggering processes. Similarly, m represents the total number of times the trigger sensor 2 is triggered, and j represents different triggering processes.

[0089] S112. Using the trigger coordinates at the end of the manipulator, by minimizing the calibration error model, determine the coordinates of the sensor in the manipulator base coordinate system and the coordinates of the center of the wafer in the manipulator end coordinate system.

[0090] For the above unconstrained nonlinear least squares optimization problem, solve it through the Levenberg-Marquardt algorithm. Obtain the coordinates (Xs1(0), Ys1(0)), (Xs2(0), Ys2(0)) of the two laser sensors relative to the manipulator base coordinate system and the coordinates (tx(0), ty(0)) of the center of the wafer relative to the manipulator end coordinate system that are pre-taught, as the initial values for the solution. Minimizing Fs can obtain the coordinates (Xs1, Ys1), (Xs2, Ys2) of the two sensors in the manipulator base coordinate system, and the coordinates of the center of the wafer in the manipulator end coordinate system are (tx, ty).

[0091] S120. Based on the coordinates of the center of the wafer, establish a tool coordinate system at the center of the wafer, and teach the target position of the wafer loading table.

[0092] Please further refer to Figure 6 , Figure 6 which is a schematic flowchart of an embodiment of step S120 of this application. As Figure 6 , step S120 further includes the following sub-steps:

[0093] S121. Based on the coordinates of the center of the wafer, establish the reference tool coordinate system of the manipulator at the center of the wafer.

[0094] Take the center of the wafer as the center point of the manipulator tool coordinate system, and establish the reference tool coordinate system of the manipulator according to the coordinates of the center of the wafer in the manipulator end coordinate system, where the attitude of the tool is Euler angles (0°, 0°, 0°).

[0095] S122. Under the reference tool coordinate system of the manipulator, teach the target position of the wafer loading table.

[0096] Under the action of the reference tool coordinate system, the manipulator moves the wafer so that the center of the wafer aligns with the center point of the loading position of the loading table. The manipulator controller teaches and maintains the current position coordinates of the manipulator to obtain the target position.

[0097] S130. Control the manipulator to carry the wafer to be rectified according to the target position, and collect the transmission trigger data during the carrying process.

[0098] Please refer further to Figure 7 , Figure 7 , which is a schematic flow chart of an embodiment of step S130 of this application. As Figure 7 , step S130 further includes the following sub-steps:

[0099] S131. Calculate the first transmission joint coordinates of the manipulator based on the target position and the tool coordinate system.

[0100] Substitute the reference tool coordinate system of the manipulator and the target position into the inverse kinematics model of the manipulator to calculate the first transmission joint coordinates of the manipulator.

[0101] S132. Control the manipulator to carry the wafer to be rectified according to the first transmission joint coordinates until the transmission trigger data is generated and collected.

[0102] In the embodiment of this application, as Figure 5 shown, Figure 5 is a schematic diagram of an embodiment of sensor triggering provided by this application. Although Figure 5 shows that during the process of triggering the sensor, the movement path of the manipulator is a straight line, this application has no requirement for the movement path of the manipulator. Here, it is only for convenience of description. It only needs to make the movement trajectory of the manipulator carrying the wafer generate two triggers at the edge of the wafer when passing through two sensors.

[0103] During the process of the manipulator carrying the wafer through two calibrated sensors, detect the triggering situation of the sensors, generate four trigger signals at the edge of the wafer, lock the encoder positions of each motor of the manipulator at the trigger moment through the high-speed input circuit of the manipulator driver, consider the encoder resolution, the rotation direction of the motor, the reduction ratio, and the coupling relationship of each joint, convert to obtain the joint coordinates of the manipulator, and obtain the real-time trigger coordinates of the end of the manipulator through the forward kinematics solution.

[0104] S140. Calculate the coordinates of the center of the wafer to be rectified by using the sensor coordinates and the transmission trigger data.

[0105] Please refer further to Figure 8 , Figure 8 , which is a schematic flow chart of an embodiment of step S140 of this application. As Figure 8 , step S140 further includes the following sub-steps:

[0106] S141. Establish a transmission error model.

[0107] The real-time trigger coordinates at the end of the manipulator are denoted as (Xe(i), Ye(i), 0) in position, and the attitude angles are denoted as (0, 0, Ce(i)). Assume that the coordinates of the center of the wafer to be corrected relative to the coordinate system at the end of the manipulator are (tx’, ty’). According to coordinate transformation, the coordinates of the center of the wafer to be corrected relative to the base coordinate system of the manipulator when the sensor is triggered are (Xt(i), Yt(i)), satisfying:

[0108] Xt(i) = Xe(i) + tx'cos(Ce(i)) - ty'sin(Ce(i))

[0109] Yt(i) = Ye(i) + tx'sin(Ce(i)) + ty'cos(Ce(i))

[0110] For each wafer, after being triggered by two sensors, using the four real-time coordinates of the end of the manipulator collected and combining with the coordinates of the two sensors obtained during AWC calibration, a transmission error model can be obtained:

[0111]

[0112] Among them,

[0113] Xt(i) = Xe(i0 + tx′cos(Ce(i)) - ty′sin(Ce(i))

[0114] Yt(i) = Ye(i) + tx′sin(Ce(i)) + ty′cos(Ce(i))

[0115] Xt(j) = Xe(j) + tx′cos(Ce(j)) - ty′sin(Ce(j))

[0116] Yt(j) = Ye(j) + tx′sin(Ce(j)) + ty′cos(Ce(j))

[0117] S142. Using the sensor coordinates and the transmission trigger data, by minimizing the transmission error model, calculate the coordinates of the center of the wafer to be corrected.

[0118] By solving the above optimization problem through the Levenberg-Marquardt algorithm, minimizing Fs can calculate the accurate coordinate value of the center of the wafer in the coordinate system at the end of the manipulator, that is, the tool value (tx’, ty’) with the center of the wafer as the TCP point.

[0119] When there is a notch on the wafer, data can be analyzed during the sampling stage to filter out the trigger data of possible wafer notches. Alternatively, when calculating, four sets of solutions can be obtained using the trigger data of any three manipulators, and the set of solutions that minimizes Fs can be selected as the final tool value at the center of the wafer.

[0120] S150. Based on the coordinates of the center of the wafer to be corrected and the target position, adjust the joint angles of the manipulator to complete the position correction of the center of the wafer.

[0121] Please further refer to Figure 9 , Figure 9 which is a schematic flowchart of an embodiment of step S150 of this application. As Figure 9 , step S150 further includes the following sub-steps:

[0122] S151. Based on the coordinates of the center of the wafer to be corrected, establish the real-time tool coordinate system of the manipulator at the center of the wafer to be corrected.

[0123] Take the center of the wafer to be corrected as the center point of the tool coordinate system of the manipulator, and establish the real-time tool coordinate system of the manipulator according to the coordinates of the center of the wafer to be corrected in the end-effector coordinate system of the manipulator, where the attitude of the tool is the Euler angle [0°, 0°, 0°].

[0124] S152. In the real-time tool coordinate system, calculate the second transfer joint coordinates of the manipulator based on the target position and complete the position correction of the center of the wafer.

[0125] When the manipulator transports the wafer in the reference tool coordinate system and reaches the target position, assume that the end position of the manipulator is (Xe, Ye, 0) and the attitude is the Euler angle (0, 0, Ce). Through coordinate transformation, the coordinates of the center point of the reference tool coordinate system can be obtained as (Xt, Yt):

[0126] Xt = Xe + txcos(Ce) - tysin(Ce)

[0127] Yt = Ye + txsin(Ce) + tycos(Ce)

[0128] At this time, the coordinates of the center of the wafer to be corrected are (Xw, Yw):

[0129] Xw = Xe + tx'cos(Ce) - ty'sin(Ce) ≠ Xt

[0130] Yw = Ye + tx'sin(Ce) + ty'cos(Ce) ≠ Yt

[0131] Generally, the center of the wafer to be corrected is offset relative to the reference tool coordinate system of the manipulator. Therefore, the center of the wafer to be corrected is not at the target position.

[0132] In this application, the way to achieve dynamic correction of the wafer center position is to switch the dynamic tool coordinate system of the manipulator, switch the current tool coordinate system of the manipulator to the tool coordinate system obtained by real-time calculation, so as to switch the control object of the manipulator from the current tool TCP point to the center of the wafer to be corrected. During the process of placing the wafer at the target feeding position, by adjusting the joint coordinates of the manipulator in real time, the new TCP point is controlled to reach the target position, which also makes the wafer center accurately aligned to the target feeding position, thus realizing the correction of the wafer center position.

[0133] During the process of the manipulator transporting the wafer to be corrected, the real-time tool coordinate system of the manipulator and the target position are brought into the inverse kinematics model of the manipulator, and the first transmission joint coordinates of the manipulator are calculated. According to the first transmission joint coordinates, the joint angles of the manipulator are adjusted, so that the wafer center reaches the target position, and the dynamic correction of the wafer center position is completed.

[0134] Similarly, the motion form of the manipulator is not restricted here and can be selected according to the actual situation on site.

[0135] The above content is the actual operation steps of the wafer transfer method proposed in this application in the production site. In actual production, through steps S130 - S150, the process of the manipulator picking up the wafer, dynamically correcting the wafer center position, and accurately placing the wafer at the target position on the feeding table can be realized. It should be noted that in the embodiments of this application, after the sensor position is calibrated, during the process of the manipulator transporting the wafer, when the wafer triggers the sensor area once, the center position of the wafer can be calculated, and after the calibration is completed, wafers of any size can be corrected, with good compatibility. This application ensures the high-precision handling operation of the manipulator, and realizes the dynamic correction and precise positioning of the wafer center position.

[0136] In the above implementation manner, by proposing a new method for dynamically correcting the wafer center position, the following beneficial effects are achieved:

[0137] 1. When calibrating the sensor coordinates, there is no need to pre-calibrate the tool coordinate system of the manipulator, nor to calculate the sensor coordinates using a reference wafer with a known offset or a reference wafer with an offset of zero, nor to ensure that the triggering motion of the manipulator is a straight line. And by triggering and sampling the sensor area from multiple angles, the calibration accuracy is ensured.

[0138] 2. By means of a simple tool calibration method, the teaching accuracy of the pick-and-place target position of the wafer is improved, so that the manipulator can accurately transport the wafer to be detected in place.

[0139] 3. The alignment accuracy is high. During the process of transporting the wafer, high-precision dynamic alignment of the wafer center position is achieved by switching the real-time tool coordinate system for the manipulator, avoiding the use of the theoretical tool coordinate system and considering the relative offset between the actual wafer and the reference wafer for alignment.

[0140] Please further combine Figure 10 , Figure 10 FIG.

[0141] S200. Control the manipulator to transport the wafer through the sensor area and collect the trigger coordinates at the end of the manipulator.

[0142] S210. Calibrate the coordinates of the sensor and the coordinates of the wafer center according to the trigger coordinates at the end of the manipulator.

[0143] S220. Establish a tool coordinate system at the wafer center based on the wafer center coordinates and teach the target position of the wafer placement table.

[0144] S230. Record the reference center coordinates of the wafer by means of a CCD camera.

[0145] When the wafer is at the target position of the placement table, identify the center coordinates of the wafer as (x0, y0) from the collected wafer image by means of a CCD camera, serving as the reference for the center position to compare the alignment accuracy of the wafer center.

[0146] It should be noted that since the dynamic centering deviation correction function can only correct the center position of the wafer and cannot adjust the attitude of the wafer, and the wafer may rotate during the handling process, the method of using a CCD camera to identify the coordinates of the marker points on the wafer or measuring the coordinates of any point on the wafer by a laser tracker cannot be used here to obtain the accurate deviation of the center position. This is because due to the rotation of the wafer itself, even when the center of the wafer is not deviated, the position of the marker points or the position of the target ball of the laser tracker will change, so errors will occur in the detection. Only the center of the wafer is the point that is not affected by its own rotation. Therefore, it is necessary to directly identify the center coordinates of the wafer by means of a CCD camera to eliminate the influence of the wafer's own rotation on the detection of the center position.

[0147] S240. Control the manipulator to handle the wafer to be corrected according to the target position, and collect the transmission trigger data during the handling process.

[0148] S250. Use the sensor coordinates and the transmission trigger data to calculate the coordinates of the center of the wafer to be corrected.

[0149] S260. Judge whether the calculated value of the offset of the wafer to be corrected exceeds the designed correction range.

[0150] The difference between the center coordinates of the wafer to be corrected and the center coordinates of the wafer calculated in the calibration stage is the offset of the wafer to be corrected in the coordinate system of the end of the manipulator. Obtain the designed correction range of the preset center position of the wafer, and judge whether the offset of the wafer to be corrected exceeds this range. If so, exit the test analysis and correction method; otherwise, continue with the correction test steps.

[0151] S270. Based on the coordinates of the center of the wafer to be corrected and the target position, adjust the joint angles of the manipulator to complete the correction of the center position of the wafer.

[0152] S280. Record the center coordinates of the wafer after correction through a CCD camera.

[0153] After the manipulator completes the correction of the center position of the wafer, the center coordinates of the wafer are identified as (x(i), y(i)) through a CCD camera, where i is the number of correction tests.

[0154] S290. Generate a random offset for the wafer and perform repeated correction verification.

[0155] In order to simulate the position offset of the wafer center in a large number of repeated tests, that is, to simulate the incoming material error after the manipulator picks up the wafer, and to make the rectification test process run automatically and continuously, it is necessary to generate a random and controllable offset for the wafer by the manipulator itself or external equipment after each rectification of the wafer center position, so that the center position of the wafer randomly offsets within the designed rectification range.

[0156] Please refer further to Figure 11 , Figure 11 which is a schematic flow chart of an implementation manner of step S290 of the present application. As Figure 11 shown, step S290 further includes the following sub-steps:

[0157] S291: Obtain the designed rectification range of the preset wafer center position and the current position offset of the wafer center, and determine the movable range of the wafer.

[0158] According to the expected offset ranges of the wafer in the direction perpendicular to the finger and along the finger direction required by the design, they are: (xlimit1, xlimit2), (ylimit1, ylimit2).

[0159] According to the calculation result of step S260, it can be obtained that the position offset of the current wafer center relative to the position in the coordinate system at the end of the manipulator is: (δx, δy).

[0160] The movable range of the wafer in the coordinate system at the end of the manipulator can be calculated as: (xlimit1 - δx, xlimit2 - δx), (ylimit1 - δy, ylimit2 - δy).

[0161] S292: Generate a random offset within the movable range.

[0162] Generate a random offset (xoffset, yoffset) within this range, which is:

[0163] xoffset = ((xlimit2 - δx) - (xlimit1 - δx)) * rand + (xlimit1 - δx)

[0164] yoffset = ((ylimit2 - δy) - (ylimit1 - δy)) * rand + (ylimit1 - δy)

[0165] S293: Control the manipulator to carry the wafer according to the random offset for repeated rectification verification.

[0166] The manipulator places the wafer at the loading position. To achieve the movement amounts (xoffset, yoffset) of the wafer along the finger direction and perpendicular to the finger direction, it is only necessary to move the TCP point of the manipulator relative to the loading position by a distance of (-xoffset, -yoffset), and then the new pick-up position of the manipulator after adjustment is obtained. Combining the attitude of the tool coordinate system of the manipulator at the current position relative to the base coordinate system of the manipulator (assumed to be posC), and (xtarget, ytarget) being the taught loading position of the wafer, the coordinates (x, y) of the pick-up point after adjustment can be calculated as follows:

[0167] x = xtarget + (-xoffset) * cos(posC) - (-yoffset) * sin(posC)

[0168] y = ytarget + (-xoffset) * sin(posC) + (-yoffset) * cos(posC)

[0169] Control the TCP point of the manipulator to reach this target position to pick up the wafer, and thus complete the random offset of the wafer within the design requirements. Of course, in other embodiments, this operation can also be completed with the help of external devices. Place the wafer on the external device and let it move with the wafer by this random offset value. Finally, the manipulator picks up the wafer after offset, so that the position deviation of the wafer center changes randomly within the design requirements. Such an operation is simple and can be achieved only with the participation of the manipulator, which is beneficial to the automatic and efficient progress of a large number of repeated tests.

[0170] Repeat steps S240 - S290 until test abnormal data is detected or the number of test times is met, then exit the test and perform the feasibility and stability analysis of the correction method.

[0171] The above content is the application process of the wafer transfer method proposed in this application for automatic and efficient stability testing in a laboratory environment. This application conducts 5000 handling tests on wafers with a radius of 150 mm, records the position of the wafer center obtained by the camera after each correction, and through analyzing the distribution of the center positions, the position correction accuracy of the wafer center can be obtained. The designed correction range of the wafer center position is set to ±5 mm, and the pixel equivalent of the CCD camera is measured to be 0.0457 mm / pixel. The experimental results show that: the maximum error of the correction distance of the wafer center position is only 0.0542 mm, the average error is only 0.03157 mm, and the standard deviation is 0.0117 mm; thus, it can be seen that the wafer transfer method of this application has extremely high correction accuracy for the wafer center position.

[0172] In the above embodiments, by proposing a new dynamic correction method for the center position of the wafer, the following beneficial effects are achieved:

[0173] 1. When calibrating the sensor coordinates, there is no need to pre-calibrate the tool coordinate system of the manipulator, nor to calculate the sensor coordinates using a reference wafer with a known offset or a reference wafer with an offset of zero. There is also no need to ensure that the trigger movement of the manipulator is a straight line. By triggering and sampling the sensor area from multiple angles, the calibration accuracy is guaranteed.

[0174] 2. Through a simple tool calibration method, the teaching accuracy of the target position for wafer picking and placing is improved, so that the manipulator can accurately transport the wafer to be detected in place.

[0175] 3. The correction accuracy is high. During the process of transporting the wafer, high-precision dynamic correction of the center position of the wafer is achieved by switching the real-time tool coordinate system of the manipulator, avoiding the use of the theoretical tool coordinate system and considering the relative offset between the actual wafer and the reference wafer for correction.

[0176] 4. There is no need to rely on external equipment. Only through the manipulator itself can a controllable random offset be generated for the wafer, and the test process runs automatically and efficiently without manual intervention. The feasibility and stability of the correction method can be quickly verified, and the correction accuracy can be obtained.

[0177] Those skilled in the art can understand that in the above method of the specific embodiment, the writing order of each step does not mean a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.

[0178] To implement the above wafer transfer method, the present application also proposes a wafer transfer device. For details, please refer to Figure 12 , Figure 12 which is a schematic structural diagram of an embodiment of the wafer transfer device provided by the present application.

[0179] The wafer transfer device 600 of this embodiment includes a processor 61, a memory 62, an input / output device 63, and a bus 64.

[0180] The processor 61, the memory 62, and the input / output device 63 are respectively connected to the bus 64. The memory 62 stores program data, and the processor 61 is used to execute the program data to implement the wafer transfer method described in the above embodiment.

[0181] In an embodiment of the present application, the processor 61 may also be referred to as a CPU (Central Processing Unit). The processor 61 may be an integrated circuit chip with signal processing capabilities. The processor 61 may also be a general-purpose processor, a digital signal processor (DSP, Digital Signal Process), an application specific integrated circuit (ASIC, Application Specific Integrated Circuit), a field programmable gate array (FPGA, Field Programmable Gate Array), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. The general-purpose processor may be a microprocessor or the processor 61 may also be any conventional processor, etc.

[0182] The present application also provides a computer storage medium. Please continue to refer to Figure 13 , Figure 13 FIG. is a schematic structural diagram of an embodiment of the computer storage medium provided by the present application. The computer storage medium 700 stores a computer program 71. When the computer program 71 is executed by a processor, it is used to implement the wafer transfer method in the above embodiment.

[0183] When the embodiments of the present application are implemented in the form of software function units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor to execute all or part of the steps of the methods described in various embodiments of the present application. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0184] The above are only the embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A wafer transfer method, characterized in that, The wafer transfer method includes: Controlling a manipulator to carry a wafer through a sensor area and collecting the trigger coordinates at the end of the manipulator; Calibrating the sensor coordinates and the coordinates of the wafer center based on the trigger coordinates at the end of the manipulator; Establishing a tool coordinate system at the center of the wafer based on the coordinates of the wafer center and teaching the target position of the wafer loading table; Controlling the manipulator to carry the wafer to be corrected according to the target position, and collecting the transmission trigger data during the carrying process; Calculating the coordinates of the center of the wafer to be corrected by using the sensor coordinates and the transmission trigger data; Adjusting the joint angles of the manipulator based on the coordinates of the center of the wafer to be corrected and the target position to complete the position correction of the center of the wafer.

2. The wafer transfer method according to claim 1, wherein: The controlling a manipulator to carry a wafer through a sensor area and collecting the trigger coordinates at the end of the manipulator includes: Determining the motion range and sampling trajectory of the manipulator; Controlling the manipulator to carry the wafer through the sensor area according to the motion range and the sampling trajectory, and collecting the trigger coordinates at the end of the manipulator.

3. The wafer transfer method according to claim 1, wherein: The calibrating the sensor coordinates and the coordinates of the wafer center based on the trigger coordinates at the end of the manipulator includes: Establishing a calibration error model; Using the trigger coordinates at the end of the manipulator to determine the coordinates of the sensor in the manipulator base coordinate system and the coordinates of the wafer center in the manipulator end coordinate system by minimizing the calibration error model.

4. The wafer transfer method according to claim 1, wherein: The establishing a tool coordinate system at the center of the wafer based on the coordinates of the wafer center and teaching the target position of the wafer loading table includes: Establishing a reference tool coordinate system of the manipulator at the center of the wafer based on the coordinates of the wafer center; Teaching the target position of the wafer loading table under the reference tool coordinate system of the manipulator.

5. The wafer transfer method according to claim 1, wherein: The controlling the manipulator to carry the wafer to be corrected according to the target position and collecting the transmission trigger data during the carrying process includes: Calculating the first transmission joint coordinates of the manipulator based on the target position and the tool coordinate system; Controlling the manipulator to carry the wafer to be corrected according to the first transmission joint coordinates until the transmission trigger data is generated and collected.

6. The wafer transfer method according to claim 1, wherein: The calculating the coordinates of the center of the wafer to be corrected by using the sensor coordinates and the transmission trigger data includes: Establishing a transmission error model; Calculating the coordinates of the center of the wafer to be corrected by using the sensor coordinates and the transmission trigger data to minimize the transmission error model.

7. The wafer transfer method according to claim 1, wherein: Adjust the joint angles of the manipulator based on the coordinates of the center of the wafer to be corrected and the target position to complete the position correction of the center of the wafer, including: Establish a real-time tool coordinate system of the manipulator at the center of the wafer to be corrected based on the coordinates of the center of the wafer to be corrected; Under the real-time tool coordinate system, calculate the second transmission joint coordinates of the manipulator based on the target position and complete the position correction of the center of the wafer.

8. The wafer transfer method according to claim 1, wherein: The wafer transfer method further includes: Record the reference center coordinates of the wafer through a CCD camera; Control the manipulator to carry the wafer to be corrected according to the target position and collect the transmission trigger data during the carrying process; Calculate the coordinates of the center of the wafer to be corrected by using the sensor coordinates and the transmission trigger data; Based on the coordinates of the center of the wafer to be corrected and the reference center coordinates, determine whether the calculated offset value of the wafer to be corrected exceeds the designed correction range; If not, adjust the joint angles of the manipulator based on the coordinates of the center of the wafer to be corrected and the target position to complete the correction of the position of the center of the wafer; Record the center coordinates of the wafer after correction through a CCD camera; Generate a random offset for the wafer to perform repeated correction verification.

9. A wafer transfer device, characterized in that, The wafer transfer device includes a memory and a processor coupled to the memory; Wherein, the memory is used to store program data, and the processor is used to execute the program data to implement the wafer transfer method according to any one of claims 1 to 8.

10. A computer storage medium, characterized in that, The computer storage medium is used to store program data, and the program data, when executed by a computer, is used to implement the wafer transfer method according to any one of claims 1 to 8.

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