Control system and detection method of wafer cassette loading port

Abstract

The invention provides a control system and a detection method for a wafer cassette loading port, and relates to the technical field of intelligent control. The control system comprises a main control module which is connected with a first sensor and is connected with a distributed input and output module through a communication bus; the driving system is controlled; the distributed input and output module is connected with an actuator and a second sensor; the first sensor is used for being driven by the driving system, detecting the wafer in the wafer box, generating a first signal and transmitting the first signal to the main control module; the actuator is used for receiving and executing the action instruction issued by the main control module; the second sensor is used for generating a second signal and transmitting the second signal to the main control module; the main control module is used for judging whether the placement state of the wafer is normal or not according to the position data of the wafer returned by the driving system; and judging whether the action instruction is correctly executed according to the second signal. According to the technical scheme provided by the invention, the placement state of the wafer and whether the actuator correctly executes the action instruction can be detected.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent control, and in particular, to a control system and detection method for a wafer cassette loading port. Background Art

[0002] There are many procedures or steps in the manufacturing process of semiconductor wafers. Due to these procedures or steps, wafers need to be placed in different positions and different machines. Therefore, in the wafer manufacturing process, wafers must be transported from one place to another and even stored for a period of time to complete the necessary processes. Among them, the wafer carrier device has both storage and transportation functions and needs to be applicable to various forms of transportation and transfer devices. Therefore, it plays a very important role in the semiconductor wafer manufacturing process.

[0003] In a semiconductor manufacturing factory, wafers usually need to be efficiently transferred and positioned between different process modules on the production line. The wafer sorter is the key equipment to complete this task and is the bridge connecting different process modules, enabling wafers to be accurately transferred under the condition of being free from contamination.

[0004] The wafer sorter at least includes a wafer cassette (Front Opening Unified Pod, abbreviated as FOUP) for storing wafers, a load port for carrying the wafer cassette, and an operation manipulator for taking out wafers from the wafer cassette and storing them into the wafer cassette. The load port includes an opener and a carrying mechanism provided on the opener. When the transport cart on the semiconductor production line moves the wafer cassette in front of the load port, the wafer cassette is placed on the carrying mechanism of the load port by manual labor, a handling manipulator, or a crane. Then, the opener performs the operation of opening the wafer cassette, and then the operation manipulator takes out the wafers in the wafer cassette and transfers them between different load ports.

[0005] In the related art, the following four methods are usually adopted to control the loading port of the wafer cassette. The first method: The input and output ports of the main control board directly receive sensor signals and control externally. The actuating units are all cylinders. The disadvantage is that the system wiring is complex, the vibration is large, resulting in inaccurate detection. The second method: The main control board integrates multiple stepper motor controllers. The actuating units are all stepper motors. The disadvantages are that the system wiring is complex, the cost is high, the vibration is large during low-speed operation, and the response period is long. The third method: The control form of the input and output ports of the main control board. The up and down movement of the door of the wafer cassette is driven by a servo motor pulse, and other actuating units are cylinders. The disadvantages are that the system wiring is complex and the anti-interference ability is poor. The fourth method: The grating ruler and the low-precision encoder are used for detection, the results are inaccurate, the determination algorithm generally adopts the average value, and the robustness is poor. Data acquisition and calculation are carried out simultaneously, and the real-time performance of obtaining the original data is low and the accuracy is poor. Based on the above four methods for control, the system wiring is complex, the cost is high, and the detection accuracy is low. Summary of the Invention

[0006] Based on the above problems, the present invention provides a control system and a detection method for the loading port of a wafer cassette, which can reduce the complexity of the system wiring, reduce the cost, and improve the detection accuracy of the loading port of the wafer cassette.

[0007] In order to achieve the above effects, the technical solutions adopted by the present invention are as follows:

[0008] According to one aspect of the present invention, a control system for the loading port of a wafer cassette is proposed, including:

[0009] A main control module, connected to a first sensor and connected to a distributed input / output module through a communication bus; and controlling the drive system;

[0010] The distributed input / output module, connected to an actuator and a second sensor;

[0011] The first sensor is used to be driven by the drive system to detect the wafer located in the wafer cassette, generate a first signal and transmit it to the main control module;

[0012] The actuator is used to receive and execute the action instruction issued by the main control module through the distributed input / output module;

[0013] The second sensor is used to generate a second signal and transmit it to the main control module when the actuator executes the action instruction;

[0014] The main control module is used to determine the position data of the wafer according to the first signal, and judge whether the placement state of the wafer is normal according to the position data; and judge whether the action instruction is correctly executed according to the second signal.

[0015] According to some embodiments, in the above control system, the main control module includes a data acquisition unit and a judgment unit; wherein,

[0016] The data acquisition unit is configured to latch the encoder value read by the drive system according to the first signal as the position data of the wafer; wherein, the position data of the wafer includes: the upper surface position data and the lower surface position data of the wafer;

[0017] The judgment unit is configured to judge whether the drive system reaches a preset end position according to the encoder value, and judge whether the placement state of the wafer is normal according to the position data of the wafer when the drive system reaches the preset end position.

[0018] According to some embodiments, in the above control system, the judgment unit includes: a first judgment unit, configured to:

[0019] Determine the actual thickness of the wafer according to the position data of the wafer;

[0020] Judge whether the wafer is missing according to the actual thickness of the wafer;

[0021] When the actual thickness is 0, output a first judgment result, which is used to represent that the wafer is missing and there is no wafer; when the actual thickness is not 0, output a second judgment result, which is used to represent that the wafer is not missing and there is a wafer.

[0022] According to some embodiments, in the above control system, the judgment unit further includes: a second judgment unit, configured to:

[0023] Determine the standard thickness of the wafer; determine the thickness deviation of the wafer according to the actual thickness and the standard thickness of the wafer;

[0024] Judge whether the wafers are overlapped according to the thickness deviation;

[0025] Wherein, when the thickness deviation is greater than a preset thickness deviation value, output a third judgment result, which is used to represent that the wafers are overlapped and the placement state is abnormal; when the thickness deviation is not greater than the preset thickness deviation value, output a fourth judgment result, which is used to represent that the wafers are not overlapped and the placement state is normal.

[0026] According to some embodiments, in the above control system, the second judgment unit is further configured to:

[0027] Determine the median value obtained by sorting the actual thicknesses in ascending order as the standard thickness;

[0028] Determine the difference between the actual thickness and the standard thickness of the wafer as the thickness deviation.

[0029] According to some embodiments, in the above control system, the determination unit further includes: a third determination unit, configured to:

[0030] Determine the actual position of the wafer according to the upper surface position data of the wafer and the actual thickness;

[0031] Determine the standard position of the wafer;

[0032] Determine the position deviation of the wafer according to the actual position and the standard position of the wafer;

[0033] Judge whether the wafer is placed obliquely according to the position deviation;

[0034] Wherein, when the position deviation is greater than a preset position deviation value, output a fifth judgment result for characterizing that the wafer is placed obliquely and the placement state is abnormal; when the position deviation is not greater than the preset position deviation value, output a sixth judgment result for characterizing that the wafer is not placed obliquely and the placement state is normal.

[0035] According to some embodiments, in the above control system, the third determination unit is further configured to: determine the absolute value of the difference between the actual position and the standard position of the wafer as the position deviation.

[0036] According to some embodiments, in the above control system, the determination unit further includes an execution order determination unit, configured to:

[0037] Determine whether to execute the second determination unit and / or the third determination unit according to the determination result output by the first determination unit;

[0038] Wherein, when the first determination unit outputs a first determination result, it is determined not to execute the second determination unit and the third determination unit; when the first determination unit outputs a second determination result, it is determined to execute the second determination unit and / or the third determination unit.

[0039] According to some embodiments, in the above control system, the second sensor is configured to:

[0040] When the actuator executes the action instruction, generate the second signal, and transmit the second signal to the main control module through the distributed input / output module at every preset time interval until the main control module determines that the action instruction is correctly executed according to the second signal.

[0041] According to some embodiments, in the above control system, the drive system includes: a driver, a motor, and a swing rod;

[0042] The swing rod is provided with the first sensor;

[0043] The driver is configured to drive the door of the wafer cassette to move up and down through the motor, and drive the swing rod to extend into the wafer cassette through the motor, so that the first sensor detects the wafers located in the wafer cassette.

[0044] According to some embodiments, in the above control system, the main control module is further configured to continuously issue the action instruction to the actuator through the distributed input / output module according to a preset period when the main control module does not receive the second signal or determines that the action instruction is not correctly executed according to the second signal.

[0045] According to some embodiments, in the above control system, the actuator is configured to perform at least one of the following operations:

[0046] Grasp / release the bottom of the wafer cassette through the clamping mechanism of the loading port;

[0047] Drive the wafer cassette to approach / away from the door panel assembly of the loading port through the carrying mechanism of the loading port;

[0048] Open / close the wafer cassette through the switching mechanism of the loading port;

[0049] Drive the door of the wafer cassette to perform a transverse or longitudinal movement through the door panel assembly.

[0050] According to some embodiments, in the above control system, the second sensor includes at least one of a hook sensor, a position sensor, and a door lock sensor.

[0051] According to an aspect of the present application, a detection method for a wafer cassette loading port is further proposed, which is applied to the above control system. The detection method includes:

[0052] Detect the wafers located in the wafer cassette through the first sensor to generate a first signal;

[0053] Determine the position data of the wafers according to the first signal;

[0054] Judge whether the placement state of the wafers is normal according to the position data.

[0055] According to some embodiments, the detecting the wafers located in the wafer cassette through the first sensor includes:

[0056] The swing rod is driven by a motor to extend into the wafer cassette, the encoder value of the drive system is recorded as the starting position of the swing rod, and the swing rod is driven to move up and down. At the same time, the first sensor detects the wafers located in the wafer cassette.

[0057] According to some embodiments, determining the position data of the wafer based on the first signal includes:

[0058] When the first signal is received, the encoder value read by the drive system is latched and used as the position data until it is determined based on the encoder value that the swing rod reaches a preset end position.

[0059] According to some embodiments, the detection method further includes:

[0060] Issuing an action instruction to the actuator through the distributed input / output module;

[0061] Receiving a second signal generated by the actuator when the action instruction is executed;

[0062] Judging whether the action instruction is correctly executed according to the second signal.

[0063] The beneficial effects of a control system and a detection method for a wafer cassette loading port provided by an embodiment of the present invention are as follows:

[0064] In the present invention, the distributed input / output module is communicatively connected to the main control module through a communication bus, and the distributed input / output module is communicatively connected to the second sensor and the actuator. It can realize the communication between the main control module and the second sensor and the actuator. Instead of using a large number of cable lines to connect from the second sensor or the actuator to the ports of the main control module, the purpose of the present invention can be achieved by using fewer communication buses. The system wiring is simple and the cost is low. The main control module in the present invention can detect the position of the wafer according to the first signal generated by the first sensor, and judge whether the actuator correctly executes the action instruction according to the second signal generated by the second sensor. The system has little vibration and high detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to more clearly illustrate the technical solutions of the present invention, the drawings required for description in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without exceeding the scope of protection required by the present invention.

[0066] Figure 1 A schematic structural diagram of a control system for a wafer cassette loading port according to an exemplary embodiment is shown;

[0067] Figure 2 Schematic diagram showing the process of obtaining position data of a wafer according to an exemplary embodiment;

[0068] Figure 3 Schematic diagram showing the process of a judgment unit according to an exemplary embodiment;

[0069] Figure 4 Schematic diagram showing the process of a first judgment unit according to an exemplary embodiment;

[0070] Figure 5 Schematic diagram showing the process of a second judgment unit according to an exemplary embodiment;

[0071] Figure 6 Schematic diagram showing the process of a third judgment unit according to an exemplary embodiment;

[0072] Figure 7 Schematic diagram showing the process of an execution order determination unit according to an exemplary embodiment;

[0073] Figure 8 Schematic diagram showing the process of a detection method according to an exemplary embodiment;

[0074] Figure 9 Schematic diagram showing the process of a detection method according to another exemplary embodiment.

[0075] Explanation of reference numerals:

[0076] 1 - Main control module, 2 - First sensor, 3 - Communication bus, 4 - Distributed input / output module, 5 - Drive system, 6 - Actuator, 7 - Second sensor. Detailed implementation manners

[0077] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. Like reference numerals in the figures denote like or similar parts, and thus their repeated description will be omitted.

[0078] In addition, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of the embodiments of the present invention. However, those skilled in the art will realize that the technical solutions of the present invention can be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. may be used. In other cases, well-known methods, devices, implementations, or operations are not shown or described in detail to avoid obscuring aspects of the present invention.

[0079] The block diagrams shown in the drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0080] The flowcharts shown in the drawings are merely illustrative and do not necessarily include all content and operations / steps, nor are they necessarily executed in the described order. For example, some operations / steps can be decomposed, while some operations / steps can be combined or partially combined, so the actual execution order may change according to the actual situation.

[0081] It should be understood that although terms such as first, second, and third may be used herein to describe various devices, these components should not be limited by these terms. These terms are used to distinguish one device from another. Therefore, the first device to be temperature-controlled described below can be referred to as the second device to be temperature-controlled without departing from the teachings of the concept of the present invention. As used herein, the term "and / or" includes any one of the associated listed items and all combinations of one or more of them.

[0082] Figure 1 The structural schematic diagram of a control system of a wafer cassette loading port according to an exemplary embodiment is shown.

[0083] As Figure 1 shown, according to one aspect of the present invention, a control system of a wafer cassette loading port is proposed, including:

[0084] A main control module 1, connected to a first sensor 2 and connected to a distributed input / output module 4 through a communication bus 3, and controls a drive system 5.

[0085] The distributed input / output module 4 is connected to an actuator 6 and a second sensor 7.

[0086] The first sensor 2 is used to be driven by the drive system 5 to detect the wafers in the wafer cassette, generate a first signal and transmit it to the main control module 1.

[0087] The actuator 6 is used to receive and execute the action instruction sent by the main control module 1 through the distributed input / output module 4.

[0088] The second sensor 7 is used to generate a second signal and transmit it to the main control module 1 when the actuator 6 executes the action instruction.

[0089] The main control module 1 is used to determine the position data of the wafer according to the first signal, and judge whether the placement state of the wafer is normal according to the position data. And judge whether the action instruction is correctly executed according to the second signal. Judging that the action instruction is correctly executed according to the second signal can indicate that the actuator 6 executes the action instruction in place, and judging that the action instruction is not correctly executed according to the second signal can indicate that the actuator 6 does not execute the action instruction in place.

[0090] In the embodiment of the present invention, the first sensor 2 may specifically be a Mapping sensor, specifically a Mapping opposed sensor. The first sensor 2 is specifically connected to the high-speed signal capture port of the main control module 1. The second sensor 7 may be a photoelectric sensor, specifically a photoelectric sensor in the visible light region and / or an infrared light region photoelectric sensor. For example, at least one of a hook sensor (Clamp / Unclamp sensor), a position sensor (Dock / Undock sensor, Latch / Unlatch sensor), and a door lock sensor (Door open / Door close sensor). In addition, a Door top / Doorbottom sensor, a placement sensor, a present sensor, a swing rod open / swing rod close sensor, etc. are also included.

[0091] The actuator 6 may be a cylinder, a motor or a hydraulic motor. The type of the communication bus 3 may be various industrial buses, specifically a CAN (Controller Area Network) bus or an Ether CAT (EtherControl Automation Technology) bus, etc. The distributed input / output module 4 transmits the second signal generated by the first sensor 2 when the actuator 6 executes the action instruction to the main control module 1 through the communication bus 3. The distributed input / output module 4 receives the action instruction issued by the main control module 1 through the communication bus 3, and controls the actuator 6 to execute corresponding actions according to the action instruction.

[0092] In the embodiment of the present invention, the drive system 5 includes: a driver, a motor and a swing rod.

[0093] The swing rod is provided with the first sensor 2.

[0094] The driver is used to drive the door of the wafer cassette to move up and down through the motor, and drive the swing rod to extend into the wafer cassette through the motor, so that the first sensor 2 detects the wafer located in the wafer cassette.

[0095] Among them, the swing rod can specifically be a Mapping rod. The driver is specifically connected to the position feedback signal port of the main control module 1. When the main control module 1 receives the first signal, it latches the encoder value returned by the drive system 5 as the position data of the wafer. The main control module 1 and the drive system 5 can be connected through the communication bus 3. Specifically, the driver in the main control module 1 and the drive system 5 can be connected through the communication bus 3. The driver can be a servo driver, and the motor can be a servo motor or a stepper motor, etc. The main control module 1 controls the driver to make the motor drive the door plate assembly of the loading port and the door of the wafer cassette downward to the bottom through the guide rail and the lead screw, so that the upper edge of the door of the wafer cassette is lower than the lower edge of the door, that is, the door of the wafer cassette is in a fully open state, and the wafers inside the wafer cassette are completely within the operable range of the handling robot. At this time, the first sensor 2 on the swing rod moves up and down with the door of the wafer cassette. Among them, when the upper edge of the door of the wafer cassette is lower than the lower edge of the door (that is, the door of the wafer cassette is in a fully open state), the first sensor 2 completes the detection of all the wafers in the wafer cassette. The above key detection action execution unit uses a servo motor or a stepper motor, which improves the positioning accuracy and has a high cost performance.

[0096] According to some embodiments, in the above control system, the main control module 1 includes a data acquisition unit and a judgment unit. Among them,

[0097] The data acquisition unit is used to latch the encoder value read by the drive system 5 according to the first signal as the position data of the wafer. Among them, the position data of the wafer includes: the upper surface position data and the lower surface position data of the wafer. The encoder value can be a servo high-resolution encoder value.

[0098] The judgment unit is used to judge whether the drive system 5 reaches the preset end position according to the encoder value, and when the drive system 5 reaches the preset end position, judge whether the placement state of the wafer is normal according to the position data of the wafer.

[0099] Figure 2 A schematic diagram showing the process of obtaining the position data of the wafer according to an exemplary embodiment.

[0100] As Figure 2As shown, in an embodiment of the present invention, taking the process of the motor driving the door plate assembly of the loading port and the door of the wafer cassette to move downward to the bottom through the guide rail and the lead screw as an example, the above specific steps are described. Initialize the buffer area, drive the swing rod to extend into the wafer cassette through the motor, and record the encoder value as the starting position of the swing rod. The motor starts, drives the swing rod to move up and down through the guide rail and the lead screw. At the same time, the first sensor 2 detects the wafers located in the wafer cassette. When the first sensor 2 is blocked by the wafers, a first signal, that is, a jump signal, is generated and transmitted to the main control module 1. When the main control module 1 receives the first signal, the data acquisition unit latches the encoder value read by the drive system 5 as the position data of the wafers and stores it in the buffer area. In the case where the main control module 1 does not receive the first signal, the data acquisition unit does not perform latching. The judgment unit judges whether the drive system 5 reaches the preset end position according to the encoder value. Specifically, when the swing rod of the drive system 5 reaches the preset end position, the first sensor 2 completes the scanning of all wafers, the upper edge of the door of the wafer cassette is lower than the lower edge of the door, and the door of the wafer cassette is in a fully open state. In the case where the drive system 5 reaches the preset end position, it is judged whether the placement state of the wafers is normal according to the position data of the wafers collected by the data acquisition module. The placement state of the wafers includes at least one of missing placement, overlapping placement, and / or inclined placement.

[0101] As Figure 2 shown, in an embodiment of the present invention, the data acquisition and the judgment of the placement state of the wafers are carried out separately, which reduces the load of the main control module 1 during the data acquisition process and ensures the real-time performance and accuracy of the position data of the wafers.

[0102] Figure 3 The figure shows a schematic diagram of the flow of the judgment unit according to an exemplary embodiment.

[0103] As Figure 3 shown, the actual thickness, actual position, standard position, and effective number of wafers of the wafers can be calculated first, and then it is judged whether to calculate the standard thickness according to whether the effective number of wafers is 0. Finally, the placement state of the wafers is judged. An effective number of wafers being 0 means that there are no wafers in the wafer cassette and it is an empty cassette.

[0104] It is also possible to perform corresponding calculations when judging different placement states of the wafers. For example, when judging whether the wafers are inclined, the actual thickness of the wafers can be calculated, the actual position of the wafers can be determined according to the upper surface position data and the actual thickness of the wafers, the standard position of the wafers can be calculated, the position deviation of the wafers can be calculated according to the actual position and the standard position of the wafers, and it can be judged whether the wafers are inclined according to the position deviation.

[0105] According to some embodiments, in the above control system, the judgment unit includes: a first judgment unit, a second judgment unit, a third judgment unit, and an execution order determination unit. The judgment unit may specifically be a single-chip microcomputer, and specifically, the first judgment unit, the second judgment unit, the third judgment unit, and the execution order determination unit may be corresponding single-chip microcomputers.

[0106] Figure 4 The schematic diagram showing the flow of the first judgment unit according to an exemplary embodiment. The first judgment unit is used to judge whether a wafer is missing.

[0107] As Figure 4 shown, the specific steps for the first judgment unit to judge whether a wafer is missing are as follows:

[0108] Initialize the buffer. The buffer is used to store calculation data, such as data of the actual thickness, standard thickness, actual position, standard position, number of valid wafers, etc. of the wafer.

[0109] Determine the actual thickness of the wafer according to the position data of the wafer. The actual thickness of the wafer is the difference between the upper surface position data and the lower surface position data of the wafer. Store the actual thickness of the wafer in the buffer. The number of wafers with non-zero actual thickness in the buffer is the number of valid wafers.

[0110] Judge whether the wafer is missing according to the actual thickness of the wafer.

[0111] In the case where the actual thickness is 0, output a first judgment result, which is used to represent that the wafer is missing and there is no wafer. In the case where the actual thickness is not 0, output a second judgment result, which is used to represent that the wafer is not missing and there is a wafer.

[0112] Figure 5 The schematic diagram showing the flow of the second judgment unit according to an exemplary embodiment. The second judgment unit is used to judge whether wafers are overlapped.

[0113] It is also used to determine the median value obtained by sorting the actual thicknesses in size as the standard thickness. The median value can avoid the influence of extreme values.

[0114] Determine the thickness deviation as the difference between the actual thickness and the standard thickness of the wafer.

[0115] As Figure 5 shown, the specific steps for the second judgment unit to judge whether wafers are overlapped are as follows:

[0116] Determine the standard thickness of the wafer. Determine the thickness deviation of the wafer based on the actual thickness and the standard thickness of the wafer. Among them, in special cases, the standard thickness is determined according to the following method. For example, when the number of valid wafers is 1, the standard thickness is the preset value or the previous standard thickness. When the number of valid wafers is 2, the standard thickness is the thickness of the thinner wafer among the two wafers. For example, if the actual thicknesses of the two wafers are 0.7 mm and 0.8 mm respectively, the standard thickness is 0.7 mm.

[0117] Judge whether the wafers are overlapped according to the thickness deviation.

[0118] Among them, when the thickness deviation is greater than the preset thickness deviation value, output the third judgment result, which is used to characterize that the wafers are overlapped and the placement state is abnormal. When the thickness deviation is not greater than the preset thickness deviation value, output the fourth judgment result, which is used to characterize that the wafers are not overlapped and the placement state is normal.

[0119] Figure 6 The schematic diagram showing the flow of the third judgment unit according to an exemplary embodiment, and the third judgment unit is used to judge whether the wafers are placed obliquely.

[0120] It is also used to: determine the absolute value of the difference between the actual position and the standard position of the wafer as the position deviation

[0121] Such as Figure 6 As shown, the specific steps for the third judgment unit to judge whether the wafers are placed obliquely are as follows:

[0122] Determine the actual position of the wafer according to the upper surface position data and the actual thickness of the wafer.

[0123] The actual position of the wafer is the sum of the upper surface position data of the wafer and 1 / 2 of the actual thickness.

[0124] Determine the standard position of the wafer.

[0125] The standard position of the wafer is the sum of the product of the starting position of the swing rod and the theoretical distance of the wafer and the number of layers (number of valid wafers - 1).

[0126] Determine the position deviation of the wafer according to the actual position and the standard position of the wafer.

[0127] Judge whether the wafers are placed obliquely according to the position deviation.

[0128] Among them, when the position deviation is greater than the preset position deviation value, output the fifth judgment result, which is used to characterize that the wafers are placed obliquely and the placement state is abnormal. When the position deviation is not greater than the preset position deviation value, output the sixth judgment result, which is used to characterize that the wafers are not placed obliquely and the placement state is normal.

[0129] Figure 7A schematic diagram showing the process of the execution order determination unit according to an exemplary embodiment is presented. The execution order determination unit is used to determine whether to execute the second determination unit and / or the third determination unit based on the determination result output by the first determination unit.

[0130] As Figure 7 shown, when the first determination unit outputs the first determination result, that is, when the number of valid wafers is 0, it is determined not to execute the second determination unit and the third determination unit. When the first determination unit outputs the second determination result, that is, when the number of valid wafers is not 0, it is determined to execute the second determination unit and / or the third determination unit.

[0131] In the embodiments of the present invention, the execution order can be: the first determination unit, the second determination unit, and the third determination unit are executed in sequence, or the first determination unit, the third determination unit, and the second determination unit are executed in sequence. The placement state of the wafers may simultaneously have abnormal placement states such as overlapping placement and tilted placement.

[0132] The main control module 1 reports the determination results output by the determination units, including the determination results output by the first determination unit, the second determination unit, and the third determination unit, to the host computer so as to timely adjust the wafers in the wafer cassette.

[0133] According to some embodiments, in the above control system, the second sensor 7 is used for:

[0134] When the actuator 6 executes the action instruction, generating a second signal, and transmitting the second signal to the main control module 1 through the distributed input / output module 4 at every preset time interval until the main control module 1 determines that the action instruction is correctly executed based on the second signal.

[0135] In the embodiments of the present invention, to improve the reliability of the control system, redundant control is adopted for system communication. The second sensor 7 transmits the second signal to the main control module 1 through the distributed input / output module 4 at every preset time interval until the main control module 1 determines that the action instruction is correctly executed based on the second signal. The main control module 1 is further used for, when the main control module 1 does not receive the second signal or determines that the action instruction is not correctly executed based on the second signal, continuously sending the action instruction to the actuator 6 through the distributed input / output module 4 according to a preset period.

[0136] In an embodiment of the present invention, the main control module 1 issues an action instruction to the distributed input / output module 4 through the communication bus 3, that is, the main control module 1 issues an action instruction to each input / output module through the communication bus 3 or receives a second signal transmitted by the second sensor 7. The main control module 1 performs logical judgment, and issues the action instruction to the corresponding actuator 6 through each input / output module, and controls the operation of the drive system 5 and collects the operation status of the drive system 5 through the communication bus 3. To improve the reliability of the control system, redundant control is adopted for system communication. The second sensor 7 transmits the second signal to the main control module 1 through the distributed input / output module 4 at preset intervals. When the main control module 1 does not receive the second signal or determines that the action instruction has not been correctly executed according to the second signal, the main control module 1 continuously issues the action instruction to the actuator 6 through the distributed input / output module 4 according to a preset period. When the main control module 1 does not receive the second signal for a long time or determines that the action instruction has not been correctly executed according to the second signal, for example, when the preset duration is exceeded, the main control module 1 gives an alarm, which can timely remind the staff to perform maintenance.

[0137] According to some embodiments, in the above control system, the actuator 6 is used to perform at least one of the following operations:

[0138] Grasp / release the bottom of the wafer cassette through the clamping mechanism of the loading port.

[0139] For example, the bottom of the wafer cassette can be grasped / released through the clamping mechanism of the loading port, and the corresponding grasping / releasing action is performed. When the grasping action is performed, the claw hooks the bottom of the wafer cassette to fix the wafer cassette. The main control module 1 obtains the second signal generated by the Clamp sensor through the distributed input / output module 4 to judge whether the clamping mechanism grasps the bottom of the wafer cassette.

[0140] Drive the wafer cassette to approach / away from the door panel assembly of the loading port through the carrying mechanism of the loading port.

[0141] For example, the carrying mechanism of the loading port can drive the wafer cassette to move forward until the wafer cassette fits with the door panel assembly, and the carrying mechanism of the loading port can also drive the wafer cassette to move backward to separate the wafer cassette from the door panel assembly. Among them, the main control module 1 can obtain the second signal generated by the Dock sensor through the distributed input / output module 4 to judge whether the wafer cassette fits with the door panel assembly. The second signal generated by the Undock sensor can be obtained through the distributed input / output module 4 to judge whether the wafer cassette is separated from the door panel assembly.

[0142] Open / close the wafer cassette through the switching mechanism of the loading port.

[0143] For example, the wafer cassette can be opened by an opener. The main control module 1 obtains the second signal generated by the Unlatch sensor through the distributed input / output module 4 to determine whether the wafer cassette is opened.

[0144] Drive the door of the wafer cassette to move horizontally or vertically through the door panel assembly.

[0145] For example, the door panel assembly can drive the already opened wafer cassette to move backward to the door opening position. The main control module 1 obtains the second signal generated by the Door open sensor through the distributed input / output module 4 to determine whether the wafer cassette has moved to the door opening position.

[0146] The present invention proposes a control system in which the main control module 1 and the distributed input / output module 4 are jointly applied. The main control module 1 and the distributed input / output module 4 are connected by a communication bus 3, with simple and reliable wiring, improving the reliability of signal transmission between moving parts and fixed parts, and at the same time simplifying the system structure and wiring. In the specific detection steps of the main control module 1, the servo high-resolution encoder value is used for actual thickness calculation, and the result is more accurate. Data acquisition and determination of the placement state of the wafer are carried out separately, reducing the load on the processor of the main control module 1 during data acquisition and ensuring the real-time and accuracy of the position data of the wafer. The result calculation method and the determination method have high reliability. The actual thickness is sorted by size and the median value is taken as the standard thickness, and the positive deviation (the difference between the actual thickness and the standard thickness is greater than the preset thickness deviation value) is used as the determination standard, which can adapt to wafers of different thickness batches, fully detect errors, and is not prone to misjudgment.

[0147] Figure 8 The flowchart showing the detection method according to an exemplary embodiment is shown. A detection method for a wafer cassette loading port is applied to the above control system, as Figure 8 shown, the detection method includes:

[0148] S101: Detect the wafer located in the wafer cassette through the first sensor to generate a first signal.

[0149] S102: Determine the position data of the wafer according to the first signal.

[0150] S103: Judge whether the placement state of the wafer is normal according to the position data.

[0151] In the embodiment of the present invention, in S101, detecting the wafer located in the wafer cassette through the first sensor includes:

[0152] Drive the swing rod into the wafer cassette through the motor, record the encoder value of the drive system as the starting position of the swing rod, and drive the swing rod to move up and down. At the same time, the first sensor detects the wafer located in the wafer cassette.

[0153] In the embodiment of the present invention, in S102, determining the position data of the wafer according to the first signal includes:

[0154] When receiving the first signal, the latch drive system reads the encoder value and uses it as the position data until it is determined according to the encoder value that the swing rod reaches the preset end position.

[0155] In S103, determining whether the placement state of the wafer is normal according to the position data includes: judging whether the wafer is missing according to the actual thickness.

[0156] Determine the standard thickness of the wafer, and determine the thickness deviation of the wafer according to the actual thickness and the standard thickness of the wafer. Judge whether the wafers are stacked according to the thickness deviation.

[0157] Determine the actual position of the wafer according to the upper surface position data and the actual thickness of the wafer, determine the standard position of the wafer, determine the position deviation of the wafer according to the actual position and the standard position of the wafer, and judge whether the wafer is placed obliquely according to the position deviation.

[0158] Determining the actual thickness of the wafer according to the position data includes: determining the difference between the upper surface position data and the lower surface position data of the wafer as the actual thickness.

[0159] Determining the standard thickness of the wafer includes: determining the median value obtained by sorting the actual thicknesses in size as the standard thickness.

[0160] Determining the thickness deviation of the wafer according to the actual thickness and the standard thickness of the wafer includes: determining the difference between the actual thickness and the standard thickness as the thickness deviation.

[0161] Determining the standard position of the wafer includes: recording the encoder value of the drive system when the motor drives the swing rod to extend into the wafer cassette as the starting position of the swing rod, and determining the standard position according to the starting position of the swing rod.

[0162] Determining the position deviation of the wafer according to the actual position and the standard position of the wafer includes: determining the absolute value of the difference between the actual position and the standard position as the position deviation.

[0163] Figure 9 The flowchart showing the detection method according to another exemplary embodiment is shown. As Figure 9 shown, the detection method further includes:

[0164] S201: Send an action instruction to the actuator through the distributed input / output module.

[0165] S202: Receive the second signal generated by the actuator when executing the action instruction.

[0166] S203: Judge whether the action instruction is correctly executed according to the second signal.

[0167] The embodiments of the present invention have been described in detail above. Specific examples are used herein to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the technical solution and its core idea of the present invention. Therefore, any changes or deformations made by those skilled in the art based on the idea of the present invention, within the specific implementation manner and application scope of the present invention, fall within the scope of protection of the present invention. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A control system for a wafer box loading port, characterized in that: include: A main control module, connected to the first sensor, and connected to the distributed input and output modules via a communication bus; and controlling the drive system; The distributed input-output module is connected to an actuator and a second sensor; The first sensor is used to be driven by the driving system to detect the wafers in the wafer box, generate a first signal and transmit it to the main control module; The actuator is used to receive and execute the action instructions sent by the main control module through the distributed input and output module; The second sensor is used to generate a second signal and transmit it to the main control module when the actuator executes the action instruction; The main control module is used to determine the position data of the wafer according to the first signal, and judge whether the placement state of the wafer is normal according to the position data; And judging whether the action instruction is executed correctly according to the second signal.

2. The control system according to claim 1, characterized in that: The main control module includes a data acquisition unit and a judgment unit; wherein, The data acquisition unit is used to latch the encoder value read by the drive system according to the first signal as the position data of the wafer; wherein the position data of the wafer includes: the upper surface position data and the lower surface position data of the wafer; The judgment unit is used to judge whether the driving system has reached a preset end position according to the encoder value, and when the driving system reaches the preset end position, judge whether the placement state of the wafer is normal according to the position data of the wafer.

3. The control system according to claim 2, characterized in that: The judging unit comprises: a first judging unit, configured to: Determine the actual thickness of the wafer according to the position data of the wafer; Determining whether the wafer is missing or not according to the actual thickness of the wafer; When the actual thickness is 0, a first judgment result is output to indicate that the wafer is missing and there is no wafer; when the actual thickness is not 0, a second judgment result is output to indicate that the wafer is not missing and there is a wafer.

4. The control system according to claim 3, characterized in that: The judging unit further includes: a second judging unit, configured to: Determining a standard thickness of the wafer; determining a thickness deviation of the wafer according to an actual thickness of the wafer and the standard thickness; Determining whether the wafers are overlapped according to the thickness deviation; Among them, when the thickness deviation is greater than the preset thickness deviation value, a third judgment result is output to characterize that the wafers are overlapped and the placement state is abnormal; when the thickness deviation is not greater than the preset thickness deviation value, a fourth judgment result is output to characterize that the wafers are not overlapped and the placement state is normal.

5. The control system according to claim 4, characterized in that: The second judgment unit is further used for: The median value obtained by sorting the actual thicknesses according to their sizes is determined as the standard thickness; The difference between the actual thickness of the wafer and the standard thickness is determined as the thickness deviation.

6. The control system according to claim 5, characterized in that: The judging unit further includes: a third judging unit, configured to: Determining the actual position of the wafer according to the upper surface position data of the wafer and the actual thickness; determining a standard position of the wafer; Determining a position deviation of the wafer according to an actual position and a standard position of the wafer; Determining whether the wafer is tilted according to the position deviation; Among them, when the position deviation is greater than the preset position deviation value, the fifth judgment result is output to characterize that the wafer is tilted and the placement state is abnormal; when the position deviation is not greater than the preset position deviation value, the sixth judgment result is output to characterize that the wafer is not tilted and the placement state is normal.

7. The control system according to claim 6, characterized in that: The third judgment unit is further used to: determine the absolute value of the difference between the actual position and the standard position of the wafer as the position deviation.

8. The control system according to claim 7, characterized in that: The judgment unit further includes an execution order determination unit, which is used to: Determine whether to execute the second judgment unit and / or the third judgment unit according to the judgment result output by the first judgment unit; Among them, when the first judgment unit outputs the first judgment result, it is determined not to execute the second judgment unit and the third judgment unit; when the first judgment unit outputs the second judgment result, it is determined to execute the second judgment unit and / or the third judgment unit.

9. The control system according to claim 1, characterized in that: The second sensor is used for: When the actuator executes the action instruction, the second signal is generated, and the second signal is transmitted to the main control module through the distributed input and output module at each preset time interval until the main control module determines that the action instruction is correctly executed based on the second signal.

10. The control system according to any one of claims 1 to 9, characterized in that: The driving system comprises: a driver, a motor and a swing rod; The swing rod is provided with the first sensor; The driver is used to drive the door of the wafer box to move up and down through the motor, and to drive the swing arm to extend into the wafer box through the motor, so that the first sensor can detect the wafer located in the wafer box.

11. The control system according to any one of claims 1 to 9, characterized in that: The main control module is also used to continuously send the action instruction to the actuator according to a preset period through the distributed input and output module when the main control module does not receive the second signal or determines that the action instruction is not correctly executed based on the second signal.

12. The control system according to any one of claims 1 to 9, characterized in that: The actuator is used to perform at least one of the following operations: Grab / release the bottom of the wafer cassette via the load port’s gripper mechanism; Driving the wafer box to approach or move away from the door panel assembly of the loading port through the carrying mechanism of the loading port; opening / closing the wafer cassette via a switch mechanism of the load port; The door of the wafer box is driven to move horizontally or vertically by the door panel assembly.

13. The control system according to any one of claims 1 to 9, characterized in that: The second sensor includes at least one of a hook sensor, a position sensor, and a door lock sensor.

14. A method for detecting a wafer box loading port, characterized in that: Applied to the control system according to any one of claims 1 to 13, the detection method comprises: Detecting the wafer in the wafer box by using the first sensor to generate a first signal; determining position data of the wafer according to the first signal; Whether the placement state of the wafer is normal is determined according to the position data.

15. The detection method according to claim 14, characterized in that: The detecting of the wafer in the wafer box by the first sensor includes: The motor drives the swing arm to extend into the wafer box, records the encoder value of the drive system as the starting position of the swing arm, and drives the swing arm to move up and down. At the same time, the first sensor detects the wafer in the wafer box.

16. The detection method according to claim 14, characterized in that: The step of determining the position data of the wafer according to the first signal comprises: When the first signal is received, the encoder value read by the drive system is latched and used as the position data until it is determined according to the encoder value that the swing arm reaches a preset end position.

17. The detection method according to any one of claims 14 to 16, characterized in that: Also includes: Sending action instructions to the actuator through the distributed input and output module; receiving a second signal generated by the actuator when executing the action instruction; Determine whether the action instruction is executed correctly according to the second signal.

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