Zero returning control method for mechanical arm

Abstract

The invention discloses a mechanical arm zero returning control method, and relates to the technical field of semiconductors. The method comprises the following steps: firstly, modeling a wafer carrying mechanical arm, and simulating a reference coordinate system xOy of the wafer carrying mechanical arm; then the wafer carrying mechanical arm is controlled to operate normally; when the two rear arms rotate in the same direction and the rotation angle is theta, alpha-beta-k * 360 = 2 theta, and alpha + beta = k * 360 + A; when the two rear arms rotate theta in the same direction and then rotate reversely, alpha + beta = k * 360 + B < k * 360 + A, and alpha-beta-k * 360 = 2 theta; and after the power is cut off and electrified again, alpha and beta are obtained, and whether the equation that alpha + beta = k * 360 + A is established is judged. According to the mechanical arm zero returning control method, quick zero returning of the wafer carrying mechanical arm can be achieved after power failure and re-electrification, cavity opening operation is not needed, time and labor are saved, the machine resetting time is shortened, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for controlling a robot arm to return to zero. Background Art

[0002] Currently, when semiconductor equipment is used to deposit wafers, a robotic arm is required to move the wafers to achieve automated transfer. However, when the current robotic arm returns to zero after power is turned off and back on, it must first retract the arm until the left and right arms hit the telescopic limit blocks, then rotate. After finding the rotation zero position, the rotation and telescopic zero positions are reset, and finally the arm positions are recalibrated. During this process, calibrating the arm positions requires opening the chamber, and the wafer deposition equipment chamber requires a series of operations such as cooling and de-vacuuming. This is time-consuming and labor-intensive, directly resulting in extended recovery time and reduced production efficiency.

[0003] In view of this, it is particularly important to design a robot arm zero return control method that can quickly return to zero and save time and effort, especially in semiconductor production. Summary of the Invention

[0004] The purpose of the present invention is to provide a robot arm zero return control method, which can realize the rapid zero return of the wafer handling robot arm after power failure and power restoration, without the need for cavity opening operation, saving time and labor, shortening the recovery time, and improving production efficiency.

[0005] The present invention is achieved by adopting the following technical solutions.

[0006] A robot arm zero return control method is applied to a wafer handling robot arm. The wafer handling robot arm includes a load-bearing arm and two support arm assemblies. The load-bearing arm includes a crossbeam and a forearm connected to each other. The support arm assembly includes a driving member, a rear arm, and a middle arm. The driving member is transmission-connected to the rear arm. The rear arm and the middle arm are hinged. One end of the crossbeam is hinged to one middle arm, and the other end is hinged to the other middle arm. The two driving members are coaxially arranged and rotate synchronously and at the same speed. The two driving members are used to drive the two rear arms to rotate in the same direction to rotate the forearms. The two driving members are also used to drive the two rear arms to rotate in opposite directions to extend and retract the forearms. The robot arm zero return control method includes: The wafer handling robot arm is modeled and its reference coordinate system xOy is simulated, where point O is the axis projection point of the drive element. When the wafer handling robot arm is at zero position, the x-axis is the angle bisector of the two rear arms, α=β, and α+β=A, where α is the angle between one rear arm and the +x-axis, β is the angle between the other rear arm and the +x-axis, and A is a constant. Control the normal operation of the wafer handling robot; when the two rear arms rotate in the same direction and the rotation angle is θ, α-β-k*360=2θ, and α+β=k*360+A; when the two rear arms rotate in the same direction by θ and then rotate in the opposite direction, α+β=k*360+B<k*360+A, and α-β-k*360=2θ, where k=1, -1 or 0, and B is a variable; After power is turned off and back on, obtain α and β, and determine whether α+β=k*360+A holds true; if so, first calculate θ through θ=(α-β-k*360) / 2, and then control the two rear arms to rotate in the same direction with a rotation angle of -θ, so that the wafer handling robot arm returns to zero position; if not, first calculate δ through δ=[A-(α+β)mod360] / 2, and then control the two rear arms to rotate in opposite directions with a rotation angle of -δ, and then control the two rear arms to rotate in the same direction with a rotation angle of -(α-β) / 2, so that the wafer handling robot arm returns to zero position.

[0007] Optionally, in the step of controlling the normal operation of the wafer handling robot arm, if the two rear arms are located on both sides of the x-axis and A is a positive number, then k = 1; if the two rear arms are located on both sides of the x-axis and A is a negative number, then k = -1; if the two rear arms are located on the same side of the x-axis, or any rear arm coincides with the x-axis, then k = 0.

[0008] Optionally, in the step of controlling the normal operation of the wafer transport robot arm, if θ is a positive number, the rear arm rotates clockwise; if θ is a negative number, the rear arm rotates counterclockwise.

[0009] Optionally, after the step of simulating the reference coordinate system xOy of the wafer handling robot arm, the robot arm zero return control method further includes: The moving coordinate system mOn of the wafer handling robot is simulated. The moving coordinate system mOn can rotate relative to the reference coordinate system xOy as the wafer handling robot rotates. The m-axis is always the angle bisector of the two rear arms.

[0010] Optionally, the wafer handling robot arm also includes a base, a magnetofluid sealed connector, a first turntable and a second turntable, and the two driving parts are respectively a first motor and a second motor. The first motor and the second motor are arranged face to face and overlap, and are both installed in the base. The first motor is connected to the first turntable through a magnetofluid sealed connector, and the second motor is connected to the second turntable through a magnetofluid sealed connector. The first turntable and the second turntable rotate in coordination, the first turntable is connected to one rear arm, and the second turntable is connected to the other rear arm.

[0011] Optionally, the first motor includes a first motor body and a first output disk, the magnetofluid sealed connector includes a magnetofluid outer shaft turntable, the first rotor of the first motor body is connected to the first output disk, the first output disk is connected to the magnetofluid outer shaft turntable through a first clamp, and the magnetofluid outer shaft turntable is connected to the first turntable.

[0012] Optionally, the second motor includes a second motor body, a second output disk and a transmission shaft, the magnetic fluid sealing connector also includes a magnetic fluid inner shaft chuck, the second motor body is arranged below the first motor body, a first clearance hole is opened in the middle of the first motor body, a second clearance hole is opened in the middle of the second motor body, the second rotor of the second motor body is connected to the second output disk, the second output disk is connected to the transmission shaft through the second clamp, the transmission shaft passes through the second clearance hole and the first clearance hole in sequence, and is connected to the magnetic fluid inner shaft chuck, and the magnetic fluid inner shaft chuck is connected to the second turntable.

[0013] Optionally, the wafer handling robot arm also includes a first angle sensor and a second angle sensor, both of which are installed in the base, the first angle sensor is used to detect the rotation angle of the first motor, and the second angle sensor is used to detect the rotation angle of the second motor.

[0014] Optionally, the number of the forearm is one, and the forearm is connected to the middle portion of the crossbeam; Alternatively, there are two forearms, which are oppositely arranged at two ends of the crossbeam and together with the crossbeam form a U-shape.

[0015] Optionally, the wafer handling robot arm further includes a synchronous belt, one end of which is connected to the outside of the hinge shaft between the crossbeam and one middle arm, and the other end is connected to the outside of the hinge shaft between the crossbeam and the other middle arm.

[0016] The robot arm zero return control method provided by the present invention has the following beneficial effects: The present invention provides a robot arm zero return control method, which first models the wafer handling robot arm and simulates the reference coordinate system xOy of the wafer handling robot arm, wherein point O is the axis projection point of the driving member, and when the wafer handling robot arm is at zero position, the x-axis is the angle bisector of the two rear arms, α=β, and α+β=A, wherein α is the angle between one rear arm and the +x-axis, β is the angle between the other rear arm and the +x-axis, and A is a constant; then the wafer handling robot arm is controlled to operate normally; when the two rear arms rotate in the same direction and the rotation angle is θ, α-β-k*360=2θ, and α+β=k*360+A; when the two rear arms rotate in the same direction by θ and then rotate in the opposite direction, α+β=k*360+ B<k*360+A, and α-β-k*360=2θ, where k=1, -1 or 0, and B is a variable; after power is cut off and restored, obtain α and β, and determine whether α+β=k*360+A holds true; if so, first calculate θ through θ=(α-β-k*360) / 2, and then control the two rear arms to rotate in the same direction with a rotation angle of -θ to return the wafer handling robot arm to zero position; if not, first calculate δ through δ=[A-(α+β)mod360] / 2, and then control the two rear arms to rotate in opposite directions with a rotation angle of -δ, and then control the two rear arms to rotate in the same direction with a rotation angle of -(α-β) / 2 to return the wafer handling robot arm to zero position. Compared with the existing technology, the robot arm return to zero control method provided by the present invention adopts the steps of judging whether α+β=k*360+A is established and controlling the rear arm in different ways when it is established or not. Therefore, it can realize the rapid return to zero of the wafer handling robot arm after power is cut off and restored to power, without the need for opening the cavity for operation, saving time and effort, shortening the recovery time, and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A schematic structural diagram from a first perspective of a wafer handling robot arm to which the robot arm zero return control method provided by the first embodiment of the present invention is applied; Figure 2 A schematic structural diagram from a second perspective of a wafer handling robot arm to which the robot arm zero return control method provided by the first embodiment of the present invention is applied; Figure 3 A schematic structural diagram from a third perspective of a wafer handling robot arm to which the robot arm zero return control method provided by the first embodiment of the present invention is applied; Figure 4 A schematic structural diagram of a first motor in a wafer handling robot arm to which the robot arm zero return control method provided by the first embodiment of the present invention is applied; Figure 5 A schematic diagram of the structure of the second motor in a wafer handling robot arm to which the robot arm zero return control method provided by the first embodiment of the present invention is applied; Figure 6 A schematic structural diagram of a magnetic fluid sealed connector in a wafer handling robot arm to which the robot arm zero return control method provided by the first embodiment of the present invention is applied; Figure 7 A model diagram of the robot arm zero return control method provided by the first embodiment of the present invention when the wafer handling robot arm is at zero position; Figure 8 A model diagram of the robot arm zero return control method provided by the first embodiment of the present invention after the wafer handling robot arm rotates a certain angle; Figure 9 A model diagram of the robot arm zero return control method provided by the first embodiment of the present invention after the wafer handling robot arm rotates a certain angle and extends a certain distance; Figure 10 A schematic structural diagram of a wafer handling robot arm to which the robot arm zero return control method provided in the second embodiment of the present invention is applied.

[0019] Icons: 100-wafer handling robot arm; 110-carrying arm; 111-crossbeam; 112-forearm; 120-support arm assembly; 121-driving element; 122-rear arm; 123-middle arm; 124-first motor; 1241-first motor body; 1242-first output disk; 1243-first stator; 1244-first rotor; 1245-first clamp; 1246-first clearance hole; 125-second motor; 1251-second motor Main body; 1252-second output disk; 1253-transmission shaft; 1254-second clearance hole; 1255-second rotor; 1256-second stator; 1257-second clamp; 130-base; 140-magnetic fluid sealing connector; 141-magnetic fluid outer shaft turntable; 142-magnetic fluid inner shaft chuck; 150-first turntable; 160-second turntable; 170-first angle sensor; 180-second angle sensor; 190-synchronous belt. DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0022] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0023] In the description of the present invention, it should be noted that the terms "inner," "outer," "upper," "lower," and "horizontal" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships in which the inventive product is typically placed when in use. These terms are intended solely to facilitate the description of the present invention and simplify the description, and are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third," etc., are used solely for distinction and should not be construed as indicating or implying relative importance.

[0024] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "connected," "installed," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0025] The following describes some embodiments of the present invention in detail with reference to the accompanying drawings. In the absence of conflict, the features of the following embodiments can be combined with each other.

[0026] First embodiment Please refer to Figures 1 to 6 The present invention provides a method for controlling a zero return of a wafer handling robot arm 100, which is used for precise zero return. This method can quickly return the wafer handling robot arm 100 to zero after power is restored after a power outage, eliminating the need for chamber operation. This method saves time and effort, shortens the recovery time, and improves production efficiency.

[0027] It should be noted that the robot arm zero return control method is applied to the wafer handling robot arm 100, which is used to carry wafers to achieve automated transfer of wafers, thereby improving the deposition efficiency of the wafers.

[0028] The wafer handling robot 100 includes a load-bearing arm 110 and two support arm assemblies 120. The load-bearing arm 110 includes a crossbeam 111 and a forearm 112, which are interconnected. The forearm 112 is used to carry wafers, which are placed at the end of the forearm 112 away from the crossbeam 111, that is, the wafer is placed at the free end of the forearm 112. The support arm assembly 120 includes a drive member 121, a rear arm 122, and a middle arm 123. The drive member 121 is in transmission connection with the rear arm 122, and the rear arm 122 is hingedly connected to the middle arm 123. One end of the crossbeam 111 is hingedly connected to one middle arm 123, and the other end is hingedly connected to the other middle arm 123. In other words, the two middle arms 123 are hingedly connected through the crossbeam 111. Both middle arms 123 can rotate relative to the crossbeam 111, and the crossbeam 111 can simultaneously limit the position of both middle arms 123. Specifically, the two driving members 121 are coaxially arranged and rotate synchronously and at the same speed. Each driving member 121 can drive a rear arm 122 to rotate. The two driving members 121 are used to drive the two rear arms 122 to rotate in the same direction, so as to drive the front arm 112 to rotate through the two middle arms 123 and a cross beam 111. The two driving members 121 are also used to drive the two rear arms 122 to rotate in the opposite direction, so as to drive the front arm 112 to extend and retract through the two middle arms 123 and a cross beam 111.

[0029] In this embodiment, there are two forearms 112, which are positioned opposite each other at the ends of the crossbeam 111 and, together with the crossbeam 111, form a U-shape. The crossbeam 111 and the two forearms 112 can rotate or extend synchronously. Specifically, each forearm 112 is used to carry a wafer, and the two forearms 112 work together to simultaneously retrieve and deliver two wafers, thereby improving handling efficiency.

[0030] Furthermore, the wafer handling robot 100 also includes a base 130, a magnetic fluid sealing connector 140, a first turntable 150 and a second turntable 160, and the two driving parts 121 are respectively a first motor 124 and a second motor 125. The first motor 124 and the second motor 125 are arranged face to face and overlap, and are both installed in the base 130. The base 130 is used to limit and fix the first motor 124 and the second motor 125. Specifically, the first motor 124 is connected to the first turntable 150 through the magnetic fluid sealing connector 140, and the second motor 125 is connected to the second turntable 160 through the magnetic fluid sealing connector 140. The magnetic fluid sealing connector 140 can achieve a stable and reliable transmission function while ensuring the sealing of the deposition chamber. In this embodiment, the first turntable 150 and the second turntable 160 rotate in coordination, and the first turntable 150 and the second turntable 160 can limit each other to ensure rotation accuracy; the first turntable 150 is connected to one rear arm 122, and the second turntable 160 is connected to the other rear arm 122 to realize the independent rotation function of the two rear arms 122 under the action of the first motor 124 and the second motor 125 respectively.

[0031] The first motor 124 includes a first motor body 1241 and a first output disk 1242. The magnetic fluid sealed connector 140 includes a magnetic fluid outer shaft turntable 141. The first stator 1243 of the first motor body 1241 is fixedly connected to the base 130 to fix the position of the first motor body 1241. The first rotor 1244 of the first motor body 1241 is connected to the first output disk 1242. The first output disk 1242 is connected to the magnetic fluid outer shaft turntable 141 via a first clamp 1245. The magnetic fluid outer shaft turntable 141 is connected to the first turntable 150. Specifically, when the first motor body 1241 is started, the first rotor 1244 drives the first output disk 1242 to rotate, so as to drive the first turntable 150 to rotate through the magnetic fluid outer shaft turntable 141, thereby driving a rear arm 122 to rotate. The first output disk 1242 is connected to the magnetic fluid outer shaft turntable 141 through the first clamp 1245, which can realize the rigid transmission of the corresponding rear arm 122 and ensure precise control of the rotation angle of the rear arm 122.

[0032] The second motor 125 includes a second motor body 1251, a second output disk 1252, and a drive shaft 1253. The magnetic fluid sealed connector 140 also includes a magnetic fluid inner shaft chuck 142. The second motor body 1251 is positioned below the first motor body 1241. A first clearance hole 1246 is defined in the center of the first motor body 1241, and a second clearance hole 1254 is defined in the center of the second motor body 1251. The second stator 1256 of the second motor body 1251 is fixedly connected to the base 130 to secure the position of the second motor body 1251. The second rotor 1255 of the second motor body 1251 is connected to the second output disk 1252, which is connected to the drive shaft 1253 via a second clamp 1257. The drive shaft 1253 passes through the second clearance hole 1254 and the first clearance hole 1246, and is connected to the magnetic fluid inner shaft chuck 142. The magnetic fluid inner shaft chuck 142 is connected to the second rotary disk 160. Specifically, when the second motor body 1251 is started, the second rotor 1255 drives the second output disk 1252 to rotate, thereby driving the magnetic fluid inner shaft chuck 142 to rotate through the transmission shaft 1253, thereby driving the second turntable 160 to rotate, and then driving the other rear arm 122 to rotate. The second output disk 1252 is connected to the magnetic fluid inner shaft chuck 142 through the second clamp 1257 and the transmission shaft 1253, which can realize the rigid transmission of the corresponding rear arm 122, ensuring precise control of the rotation angle of the rear arm 122.

[0033] Optionally, the wafer handling robot 100 further includes a first angle sensor 170 and a second angle sensor 180. Both the first angle sensor 170 and the second angle sensor 180 are mounted within the base 130. The first angle sensor 170 is used to detect the rotation angle of the first motor 124, and the second angle sensor 180 is used to detect the rotation angle of the second motor 125, to facilitate the robot's zero return control method. In this embodiment, the first angle sensor 170 and the second angle sensor 180 are both grating scale sensors.

[0034] Optionally, the wafer handling robot 100 further includes a timing belt 190. One end of the timing belt 190 is connected to the outer cylindrical surface of the hinge axis between the crossbeam 111 and one of the middle arms 123, and the other end is connected to the outer cylindrical surface of the hinge axis between the crossbeam 111 and the other middle arm 123, to ensure synchronous movement of the two middle arms 123. In this embodiment, there are two timing belts 190, each made of steel. The two timing belts 190 work together to further improve the synchronization of the movement of the two middle arms 123.

[0035] It should be noted that since the first motor 124 is overlapped and arranged above the second motor 125, and the front of the first motor 124 faces upward and the front of the second motor 125 faces downward, when the driving directions of the first motor 124 and the second motor 125 are opposite, the rotation directions of the two rear arms 122 are the same, and when the driving directions of the first motor 124 and the second motor 125 are the same, the rotation directions of the two rear arms 122 are opposite. Based on this, when the first motor 124 and the second motor 125 are driven in the same direction and counterclockwise, the rotation directions of the two rear arms 122 are opposite, and the entire carrying arm 110 extends forward; when the first motor 124 and the second motor 125 are driven in the same direction and clockwise, the rotation directions of the two rear arms 122 are opposite, and the entire carrying arm 110 retracts backward; when the first motor 124 is driven clockwise and the second motor 125 is driven counterclockwise, the rotation directions of the two rear arms 122 are the same, and the entire carrying arm 110 rotates clockwise; when the first motor 124 is driven counterclockwise and the second motor 125 is driven clockwise, the rotation directions of the two rear arms 122 are the same, and the entire carrying arm 110 rotates counterclockwise.

[0036] Please refer to Figures 7 to 9 , the robot arm zero return control method includes the following steps: Step S110: Model the wafer handling robot 100 and simulate the reference coordinate system xOy of the wafer handling robot 100, where point O is the axis projection point of the driving member 121. When the wafer handling robot 100 is in zero position, the x-axis is the angle bisector of the two rear arms 122, α=β, and α+β=A, where α is the angle between one rear arm 122 and the +x axis, β is the angle between the other rear arm 122 and the +x axis, and A is a constant.

[0037] It should be noted that in step S110, the wafer handling robot 100 is modeled using 3D software, and the rear arm 122, middle arm 123 and beam 111 of the wafer handling robot 100 are simulated as line segments, and the driving member 121 of the wafer handling robot 100 is simulated as a circle. The circles formed by the two driving members 121 are overlapped, and the midpoint of the circle is the axis projection point of the driving member 121. The rear arm 122, middle arm 123 and beam 111 can all rotate around the axis projection point.

[0038] Furthermore, the axis projection point of the driving member 121 is set as point O, and the two rear arms 122 are connected to point O. The two rear arms 122 can rotate under the action of the two driving members 121 (the first motor 124 and the second motor 125), that is, rotate within the reference coordinate system xOy, so as to drive the beam 111 to rotate or extend through the two middle arms 123 respectively, thereby driving the front arm 112 to rotate or extend, thereby realizing the wafer handling function.

[0039] In this embodiment, when the wafer handling robot 100 is at its zero position, the rear arm 122, middle arm 123, and crossbeam 111 are all located in the second and third quadrants of the reference coordinate system xOy. At this point, the two rear arms 122 are positioned opposite each other on either side of the x-axis, with the x-axis being the angle bisector of the two rear arms 122. Specifically, the x-axis comprises two segments, the +x-axis and the -x-axis, with point O located between the +x-axis and the -x-axis. α is the angle between one rear arm 122 and the +x-axis, and β is the angle between the other rear arm 122 and the +x-axis. When the wafer handling robot 100 is at its zero position, the -x-axis is the angle bisector of the two rear arms 122.

[0040] Step S120 : simulating the moving coordinate system mOn of the wafer transport robot 100 . The moving coordinate system mOn can rotate relative to the reference coordinate system xOy as the wafer transport robot 100 rotates. The m-axis is always the angle bisector of the two rear arms 122 .

[0041] It should be noted that in step S120, to facilitate intuitive observation of the motion of the wafer handling robot 100 within the reference coordinate system xOy, a dynamic coordinate system mOn of the wafer handling robot 100 is simulated. The O point of the dynamic coordinate system mOn and the reference coordinate system xOy are the same, and both are projection points of the axis of the drive member 121. The dynamic coordinate system mOn rotates with the two rear arms 122 rotating in the same direction, and the two rear arms 122 are always positioned opposite each other on the m-axis, which always serves as the angle bisector of the two rear arms 122. Specifically, the m-axis includes two segments, the +m-axis and the -m-axis, with the O point located between the +m-axis and the -m-axis, which always serves as the angle bisector of the two rear arms 122. When the two rear arms 122 rotate in the same direction, the dynamic coordinate system mOn rotates synchronously with respect to the reference coordinate system xOy. When the two rear arms 122 rotate in opposite directions, the dynamic coordinate system mOn remains stationary relative to the reference coordinate system xOy.

[0042] Furthermore, when the wafer transport robot 100 is at zero position, the moving coordinate system mOn and the reference coordinate system xOy completely coincide with each other. At this time, the −x axis and the −m axis coincide with each other and are both angle bisectors of the two rear arms 122 .

[0043] Step S130: Control the wafer handling robot 100 to operate normally; when the two rear arms 122 rotate in the same direction and the rotation angle is θ, α-β-k*360=2θ, and α+β=k*360+A; when the two rear arms 122 rotate in the same direction by θ and then rotate in the opposite direction, α+β=k*360+B<k*360+A, and α-β-k*360=2θ, where k=1, -1 or 0, and B is a variable.

[0044] It should be noted that in step S130, if the two rear arms 122 rotate in the same direction, the beam 111 rotates relative to point O, thereby driving the front arm 112 to rotate relative to point O, thereby driving the wafer placed on the front arm 112 to rotate relative to point O; if the two rear arms 122 rotate in opposite directions, the beam 111 moves away from or closer to point O, thereby driving the front arm 112 away from or closer to point O, thereby driving the wafer placed on the front arm 112 away from or closer to point O.

[0045] Specifically, when the two rear arms 122 rotate in the same direction and the rotation angle is θ, the moving coordinate system mOn rotates by θ as the two rear arms 122 rotate in the same direction, that is, the angle between the +m axis and the +x axis is θ, α-β-k*360=2θ, and α+β=k*360+A. At this time, if the two rear arms 122 are respectively located on both sides of the x-axis and A is a positive number, then k = 1; if the two rear arms 122 are respectively located on both sides of the x-axis and A is a negative number, then k = -1; if the two rear arms 122 are located on the same side of the x-axis, or any rear arm 122 coincides with the x-axis, then k = 0.

[0046] Furthermore, when the two rear arms 122 rotate in the same direction by θ and then rotate in opposite directions, that is, the two rear arms 122 rotate in opposite directions when the angle between the +m axis and the +x axis is θ, α+β=k*360+B<k*360+A, and α-β-k*360=2θ. At this time, if the two rear arms 122 are respectively located on both sides of the x-axis and A is a positive number, then k = 1; if the two rear arms 122 are respectively located on both sides of the x-axis and A is a negative number, then k = -1; if the two rear arms 122 are respectively located on the same side of the x-axis, or either rear arm 122 coincides with the x-axis, then k = 0.

[0047] It should be noted that when the driving member 121 drives the rear arm 122 to rotate and the rotation angle is θ, if θ is a positive number, the rear arm 122 rotates clockwise; if θ is a negative number, the rear arm 122 rotates counterclockwise.

[0048] Step S140: After power is turned off and back on, obtain α and β, and determine whether α+β=k*360+A holds true; if so, first calculate θ through θ=(α-β-k*360) / 2, and then control the two rear arms 122 to rotate in the same direction and the rotation angle is -θ, so that the wafer handling robot 100 returns to the zero position; if not, first calculate δ through δ=[A-(α+β)mod360] / 2, and then control the two rear arms 122 to rotate in opposite directions and the rotation angle is -δ, and then control the two rear arms 122 to rotate in the same direction and the rotation angle is -(α-β) / 2, so that the wafer handling robot 100 returns to the zero position.

[0049] It should be noted that in step S140, after power is turned off and back on, the system reads the current values ​​of α and β and determines whether α + β = k * 360 + A holds. If so, this indicates that the wafer handling robot arm 100 only rotated before power was turned off and did not extend or retract, or that it extended but ultimately fully retracted. In this case, θ is calculated using θ = (α - β - k * 360) / 2, and the two rear arms 122 are then controlled to rotate in the same direction by an angle of -θ, returning them to their initial positions. This restores the alignment of the moving coordinate system mOn and the reference coordinate system xOy, thereby returning the wafer handling robot arm 100 to its zero position. If this is not true, it means that the wafer handling robot arm 100 not only rotated but also extended and retracted before power was cut off. At this time, first calculate δ through δ=[A-(α+β)mod360] / 2, and then control the two rear arms 122 to rotate in opposite directions and the rotation angle is -δ, so that the beam 111 is completely retracted, and then control the two rear arms 122 to rotate in the same direction and the rotation angle is -(α-β) / 2, so that the two rear arms 122 rotate to the initial position, that is, the moving coordinate system mOn and the reference coordinate system xOy are restored to the overlapping state, so that the wafer handling robot arm 100 returns to the zero position.

[0050] The robot arm zero return control method provided by the embodiment of the present invention first simulates the reference coordinate system xOy of the wafer handling robot arm 100, where point O is the axis projection point of the driving member 121. When the wafer handling robot arm 100 is at zero position, the x-axis is the angle bisector of the two rear arms 122, α=β, and α+β=A, where α is the angle between one rear arm 122 and the +x-axis, β is the angle between the other rear arm 122 and the +x-axis, and A is a constant; then the wafer handling robot arm 100 is controlled to operate normally; when the two rear arms 122 rotate in the same direction and the rotation angle is θ, α-β-k*360=2θ, and α+β=k*360+A; when the two rear arms 122 rotate in the same direction by θ and then rotate in the opposite direction, α+β=k*360 +B<k*360+A, and α-β-k*360=2θ, where k=1, -1 or 0, and B is a variable; after power is cut off and restored, obtain α and β, and determine whether α+β=k*360+A holds true; if so, first calculate θ through θ=(α-β-k*360) / 2, and then control the two rear arms 122 to rotate in the same direction and the rotation angle is -θ, so that the wafer handling robot 100 returns to the zero position; if not, first calculate δ through δ=[A-(α+β)mod360] / 2, and then control the two rear arms 122 to rotate in opposite directions and the rotation angle is -δ, and then control the two rear arms 122 to rotate in the same direction and the rotation angle is -(α-β) / 2, so that the wafer handling robot 100 returns to the zero position. Compared with the prior art, the robot arm return to zero control method provided by the present invention adopts the steps of judging whether α+β=k*360+A is established and controlling the rear arm 122 in different ways when it is established or not. Therefore, it is possible to realize the rapid return to zero of the wafer handling robot arm 100 after power is cut off and restored to power, without the need for opening the cavity for operation, saving time and effort, shortening the recovery time, and improving production efficiency.

[0051] Second embodiment Please refer to Figure 10 An embodiment of the present invention provides a wafer handling robot arm 100 . Compared with the first embodiment, the difference of this embodiment is that the length of the beam 111 is shorter and the number of forearms 112 is different.

[0052] In this embodiment, there is one forearm 112, which is connected to the middle of the beam 111. The end of the forearm 112 away from the beam 111 is used to support the wafer, that is, the wafer is placed at the free end of the forearm 112. The forearm 112 is used to support the wafer to realize the wafer picking and feeding functions.

[0053] The beneficial effects of the robot arm zero return control method provided by the embodiment of the present invention are the same as those of the first embodiment, and will not be repeated here.

[0054] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for controlling a robot arm to return to zero, characterized in that: Applicable to a wafer handling robot arm, the wafer handling robot arm includes a load-bearing arm and two support arm assemblies, the load-bearing arm includes a crossbeam and a forearm connected to each other, the support arm assembly includes a driving member, a rear arm and a middle arm, the driving member is transmission-connected to the rear arm, the rear arm is hinged to the middle arm, one end of the crossbeam is hinged to one of the middle arms, and the other end is hinged to the other middle arm, the two driving members are coaxially arranged and rotate synchronously and at the same speed, the two driving members are used to drive the two rear arms to rotate in the same direction to rotate the forearms, and the two driving members are also used to drive the two rear arms to rotate in opposite directions to extend and retract the forearms; The robot arm zero return control method includes: Model the wafer handling robot arm and simulate the reference coordinate system xOy of the wafer handling robot arm, where point O is the axis projection point of the drive member. When the wafer handling robot arm is in zero position, the x-axis is the angle bisector of the two rear arms, α=β, and α+β=A, where α is the angle between one rear arm and the +x-axis, β is the angle between the other rear arm and the +x-axis, and A is a constant. Controlling the normal operation of the wafer handling robot arm; when the two rear arms rotate in the same direction and the rotation angle is θ, α-β-k*360=2θ, and α+β=k*360+A; when the two rear arms rotate in the same direction θ and then rotate in the opposite direction, α+β=k*360+B<k*360+A, and α-β-k*360=2θ, where k=1, -1 or 0, and B is a variable; After power is cut off and restored, obtain α and β, and determine whether α+β=k*360+A is true; if true, first calculate θ through θ=(α-β-k*360) / 2, and then control the two rear arms to rotate in the same direction and the rotation angle is -θ, so that the wafer handling robot arm returns to the zero position; if not true, first calculate δ through δ=[A-(α+β)mod360] / 2, and then control the two rear arms to rotate in opposite directions and the rotation angle is -δ, and then control the two rear arms to rotate in the same direction and the rotation angle is -(α-β) / 2, so that the wafer handling robot arm returns to the zero position.

2. The robot arm zero return control method according to claim 1, wherein: In the step of controlling the normal operation of the wafer handling robot arm, if the two rear arms are respectively located on both sides of the x-axis and A is a positive number, then k = 1; if the two rear arms are respectively located on both sides of the x-axis and A is a negative number, then k = -1; if the two rear arms are located on the same side of the x-axis, or any one of the rear arms coincides with the x-axis, then k = 0.

3. The robot arm zero return control method according to claim 1, characterized in that: In the step of controlling the wafer transport robot arm to operate normally, if θ is a positive number, the rear arm rotates clockwise; if θ is a negative number, the rear arm rotates counterclockwise.

4. The robot arm zero return control method according to claim 1, characterized in that: After the step of simulating the reference coordinate system xOy of the wafer handling robot arm, the robot arm zero return control method further includes: The moving coordinate system mOn of the wafer transport robot arm is simulated. The moving coordinate system mOn can rotate relative to the reference coordinate system xOy as the wafer transport robot arm rotates, and the m-axis is always the angle bisector of the two rear arms.

5. The robot arm zero return control method according to claim 1, characterized in that: The wafer handling robot arm also includes a base, a magnetic fluid sealed connector, a first turntable and a second turntable. The two driving parts are a first motor and a second motor respectively. The first motor and the second motor are arranged face to face and overlapped, and are both installed in the base. The first motor is connected to the first turntable through the magnetic fluid sealed connector, and the second motor is connected to the second turntable through the magnetic fluid sealed connector. The first turntable and the second turntable rotate in coordination. The first turntable is connected to one of the rear arms, and the second turntable is connected to the other rear arm.

6. The robot arm zero return control method according to claim 5, characterized in that: The first motor includes a first motor body and a first output disk, the magnetic fluid sealed connector includes a magnetic fluid outer shaft turntable, the first rotor of the first motor body is connected to the first output disk, the first output disk is connected to the magnetic fluid outer shaft turntable through a first clamp, and the magnetic fluid outer shaft turntable is connected to the first turntable.

7. The robot arm zero return control method according to claim 6, characterized in that: The second motor includes a second motor body, a second output disk and a transmission shaft. The magnetic fluid sealed connector also includes a magnetic fluid inner shaft chuck. The second motor body is arranged below the first motor body. A first clearance hole is opened in the middle of the first motor body. A second clearance hole is opened in the middle of the second motor body. The second rotor of the second motor body is connected to the second output disk. The second output disk is connected to the transmission shaft through a second clamp. The transmission shaft passes through the second clearance hole and the first clearance hole in sequence and is connected to the magnetic fluid inner shaft chuck. The magnetic fluid inner shaft chuck is connected to the second turntable.

8. The robot arm zero return control method according to claim 5, characterized in that: The wafer handling robot arm also includes a first angle sensor and a second angle sensor, both of which are installed in the base. The first angle sensor is used to detect the rotation angle of the first motor, and the second angle sensor is used to detect the rotation angle of the second motor.

9. The robot arm zero return control method according to claim 1, characterized in that: The number of the forearm is one, and the forearm is connected to the middle portion of the crossbeam; Alternatively, there are two forearms, which are arranged oppositely at two ends of the crossbeam and together with the crossbeam form a U-shape.

10. The robot arm zero return control method according to claim 1, characterized in that: The wafer handling robot arm further comprises a synchronous belt, one end of which is connected to the outside of the hinge shaft between the crossbeam and one of the middle arms, and the other end of which is connected to the outside of the hinge shaft between the crossbeam and the other middle arm.

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