Linear rotation device for photolithography equipment and method for controlling rotational motion of mask plate moving stage using the same

Abstract

The present invention discloses a linear rotation device for photolithography equipment, comprising: a mask plate moving platform, used to carry the mask plate, the mask plate moving platform can perform rotational motion; a linear motion module, used to drive the mask plate moving platform to perform rotational motion through linear motion, the linear motion module including a thrust bearing; an adapter, the adapter is arranged on the mask plate moving platform, wherein the thrust bearing and one side of the adapter are kept in close contact during the rotational motion of the mask plate moving platform; an angle detection unit, used to detect the angle difference between the actual position of the mask plate and the target position; and a control unit, used to adjust the moving distance of the linear motion module according to the angle difference between the actual position of the mask plate and the target position so that the angle difference meets the preset accuracy requirement. A method for controlling the rotational motion of the mask plate moving platform using the aforementioned linear rotation device is also disclosed.

Description

Technical Field

[0001] The invention relates to the field of semiconductors, and in particular to a linear rotation device for photolithography equipment and a method for controlling the rotational motion of a mask plate moving table by using the linear rotation device. Background Art

[0002] In photolithography equipment, the motion stage subsystem requires a high-precision motion platform to align the mask and wafer with high precision to achieve high-precision overlay exposure. During the motion of the motion stage, the wafer is relatively stationary. The motion stage carries the mask and adjusts its own position to achieve alignment between the mask and wafer.

[0003] In some existing motion stages, a servo motor is connected to a worm through a coupling, and the motor drives the worm to rotate. Since the thread of the worm is meshed with the gear of the worm wheel, the worm wheel rotates at the same time as the worm rotates. The worm wheel is equipped with a cross roller bearing to withstand the radial force of the rotational motion. However, since the meshing of the gears of the worm and worm wheel generally has a gap of tens to hundreds of microns, there is a certain return gap during reverse motion, so the accuracy is poor.

[0004] Some other existing motion platforms use servo motors to drive the transmission screw to make linear motion in the vertical direction, and the positioning flexible parts push the rotating connecting shaft in the longitudinal direction, thereby driving the rotating platform to rotate. However, in these motion platform structures, the linear to rotary motion is mainly driven by the rolling bearing to push the rotating connecting shaft. The contact of the rolling bearing is a horizontal line, and the rotating connecting shaft is a vertical line. The contact between the two is point contact and sliding friction rather than rolling friction. The friction force is large, which affects the motion accuracy. At the same time, the tilt of the push bearing or the rotating connecting shaft will affect the rotation accuracy.

[0005] In view of this, it is desirable to provide an improved linear-to-rotating device for a lithography device and a method for controlling the rotational motion of a mask moving stage using the linear-to-rotating device to achieve high-precision rotational positioning. Summary of the invention

[0006] A brief summary of one or more aspects is given below to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or decisive elements of all aspects nor to define the scope of any or all aspects. Its only purpose is to give some concepts of one or more aspects in a simplified form as a preface to a more detailed description given later. The scope of the present invention is defined by the attached claims and their equivalent technical solutions.

[0007] The present invention provides a linear-to-rotating device for a lithography device, comprising: a mask plate moving table, used to carry a mask plate, the mask plate moving table can perform rotational motion; a linear motion module, used to drive the mask plate moving table to perform rotational motion through linear motion, the linear motion module comprising a thrust bearing; an adapter, which is arranged on the mask plate moving table, wherein the thrust bearing and one side of the adapter are kept in close contact during the rotational motion of the mask plate moving table; an angle detection unit, used to detect the angle difference between the actual position of the mask plate and the target position; and a control unit, used to adjust the moving distance of the linear motion module according to the angle difference between the actual position of the mask plate and the target position so that the angle difference meets the preset accuracy requirement.

[0008] In some embodiments, the apparatus includes a rotary bearing, the rotary bearing is located at the center of the mask moving stage and the mask moving stage performs a rotary motion around the rotary bearing, and wherein the angle detection unit is adhered to the rotary bearing.

[0009] In some embodiments, the linear motion module further includes a motor, a transmission screw, and a tension spring, wherein the motor drives the transmission screw and includes a stator part and a mover part, a thrust bearing is installed on the mover part, and wherein one end of the tension spring is connected to the adapter and the other end is connected to the mover part of the motor.

[0010] In some embodiments, the motor is a stepper motor or a servo motor.

[0011] In some embodiments, the thrust bearing and one side of the adapter are kept in close contact with each other by a tension spring.

[0012] In some embodiments, the moving part of the motor moves along the X-axis direction, and when the moving part moves in the positive direction along the X-axis, the thrust bearing pushes the adapter, and the mask plate moving table performs a counterclockwise rotation movement in the XY plane, and when the moving part moves in the reverse direction along the X-axis, the tension spring pulls the adapter, and the mask plate moving table performs a clockwise rotation movement in the XY plane.

[0013] In some embodiments, the thrust bearing is decoupled from the adapter in the Y-axis direction.

[0014] In some embodiments, the angle detection unit includes a grating scale or a magnetic scale.

[0015] In some embodiments, the linear motion module has a minimum step distance, and the mask motion stage rotates a minimum step angle when the linear motion module moves the minimum step distance, wherein the minimum step angle meets a preset accuracy requirement.

[0016] The present invention also provides a method for controlling the rotational motion of a mask plate moving table by using the aforementioned linear-to-rotation device for lithography equipment, comprising the following steps: S1: placing the mask plate on the mask plate moving table, wherein the center of the mask plate coincides with the center of the mask plate moving table; S2: determining the initial angle difference between the initial position of the mask plate and the target position; S3: determining the distance that the linear motion module needs to move based on the initial angle difference; S4: causing the linear motion module to perform linear motion to drive the mask plate moving table to perform rotational motion until the linear motion module moves a corresponding distance; S5: determining whether the actual angle difference between the actual position of the mask plate and the actual angle difference between the target position meets the preset accuracy requirement; S6: if the actual angle difference does not meet the preset accuracy requirement, determining the distance that the linear motion module needs to move based on the actual angle difference; S7: repeating steps S4 to S6 until the actual angle difference between the actual position of the mask plate and the actual angle difference between the target position meets the preset accuracy requirement.

[0017] In some embodiments, the method further includes: when the actual angle difference between the actual position of the mask plate and the actual angle difference between the target position meets the preset accuracy requirement, stopping the motor of the linear motion module and maintaining a constant torque.

[0018] In some embodiments, determining the distance that the linear motion module needs to move according to the initial angle difference or the actual angle difference further includes determining the distance that the linear motion module needs to move by the following formula:

[0019] X = α*L

[0020] Wherein, X represents the distance that the linear motion module needs to move, α represents the initial angle difference or the actual angle difference, and L represents the distance between the thrust bearing and the rotation center of the mask plate motion stage.

[0021] The technical solution of the present invention eliminates the return gap by keeping the thrust bearing and one side of the adapter in close contact at all times. The angle detection unit is set to detect the angle difference between the actual position of the mask plate and the target position, and the moving distance of the linear motion module is gradually adjusted according to the angle difference, thereby achieving high-precision positioning of the linear rotation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The features, nature and advantages of the present invention will become more apparent when the detailed description set forth below is understood in conjunction with the accompanying drawings. It should be noted that the accompanying drawings described are only schematic and non-restrictive. In the accompanying drawings, the sizes of some components may be exaggerated and not drawn to scale for illustrative purposes.

[0023] Figure 1 The figure shows the overall structure of a linear-to-rotating device for a lithography device according to an embodiment of the present invention.

[0024] Figure 2A perspective view of a linear motion module according to an embodiment of the present invention is shown.

[0025] Figure 3 A cross-sectional view of a linear motion module according to an embodiment of the present invention is shown.

[0026] Figure 4 A schematic diagram of eliminating the return clearance between a thrust bearing and an adapter according to an embodiment of the present invention is shown.

[0027] Figure 5 A schematic diagram showing rotational positioning of a mask moving stage according to an embodiment of the present invention is shown.

[0028] Figure 6 and Figure 7 A schematic diagram showing an angle adjustment when a mask moving stage is rotationally positioned according to an embodiment of the present invention is shown.

[0029] Figure 8 A schematic scheme for controlling the rotational motion of a mask moving stage according to an embodiment of the present invention is shown.

[0030] Fig. 9 A flow chart of a method for controlling the rotational motion of a mask moving stage by using a linear-to-rotation device according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. In the following detailed description, many specific details are set forth to provide a thorough understanding of the described exemplary embodiments. However, it is obvious to those skilled in the art that the described embodiments can be practiced without some or all of these specific details. In other exemplary embodiments, well-known structures are not described in detail to avoid unnecessarily obscuring the concepts of the present disclosure. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. At the same time, in the absence of conflict, the various aspects described in the embodiments can be combined arbitrarily.

[0032] As mentioned above, some linear-to-rotation schemes in the prior art have return gaps and poor positioning accuracy. Other linear-to-rotation schemes use rolling bearings to drive the rotating connecting shaft. The rolling bearing contact is a horizontal line, and the rotating connecting shaft is a vertical line. The contact between the two is point contact and is sliding friction rather than rolling friction. The friction force is large, which affects the motion accuracy. In addition, the installation tilt of the push bearing or the rotating connecting shaft will affect the rotation accuracy.

[0033] The technical solution of this application uses a linear motion module that performs linear motion in the horizontal longitudinal (X-axis) direction as a driving component to push the mask plate motion stage to perform rotational motion in the XY plane, thereby improving the calculation accuracy of the rotation angle during linear rotation. In addition, an angle detection unit is provided to detect the angle difference between the actual position of the mask plate and the target position and feed it back to the control unit. The control unit gradually adjusts the moving distance of the linear motion module according to the angle difference, thereby achieving high-precision positioning of the linear rotation. The thrust bearing and the adapter fixed to the mask plate motion stage are always kept in close contact by pre-tightening the tension spring, and the return gap is eliminated during the movement of the mask plate motion stage, thereby further improving the positioning accuracy.

[0034] Figure 1 The figure shows the overall structure of a linear-to-rotating device 100 for a lithography device according to an embodiment of the present invention.

[0035] As shown in the figure, the linear-to-rotating device 100 of the present invention includes a mask plate motion platform, a rotary bearing, an angle detection unit, an adapter and a linear motion module.

[0036] The mask plate motion stage is used to carry the mask plate and can perform rotational motion. In various embodiments of the present invention, the mask plate motion stage can perform both counterclockwise rotational motion and clockwise rotational motion. The rotation bearing is located at the center of the mask plate motion stage and the mask plate motion stage performs rotational motion around the rotation bearing. As shown in the figure, the mask plate motion stage performs rotational motion around the Z axis in the XY plane.

[0037] The linear motion module is used to drive the mask plate motion stage to perform rotational motion through linear motion. As shown in the figure, the linear motion module performs linear motion in the X-axis direction. It should be noted that Figure 1 The X, Y, and Z axes shown in are exemplary.

[0038] One end of the adapter is fixedly mounted on the mask plate motion stage, and the other end is clamped on the thrust bearing of the linear motion module (hereinafter Figure 2 ), thereby connecting the linear motion module and the mask plate motion stage. During the rotational motion of the mask plate motion stage, the thrust bearing of the linear motion module is kept in close contact with one side of the adapter.

[0039] The angle detection unit is used to detect the angle difference between the actual position of the mask plate and the target position.

[0040] In some embodiments, the angle detection unit may be adhered to the rotary bearing.

[0041] In some embodiments, the angle detection unit may include a grating scale, such as a gold-plated steel tape grating scale, an indium steel tape grating scale, an aluminum tape grating scale, etc. In other embodiments, the angle detection unit may include a magnetic grating scale.

[0042] In addition, the linear rotation device 100 further includes a control unit ( Figure 1 ). The angle detection unit can feed back the angle difference between the actual position of the mask and the target position to the control unit, and the control unit adjusts the moving distance of the linear motion module according to the angle difference so that the angle difference meets the preset accuracy requirement. In various embodiments of the present invention, the control unit can communicate with each module / unit of the linear rotation device 100 to control the operation of these modules / units. For example, the control unit can communicate with the angle detection unit to receive the fed-back angle difference from the angle detection unit. In some other examples, the control unit can communicate with the linear motion module to instruct the linear motion module to move a corresponding distance.

[0043] In some embodiments, the control unit may include any suitable controller (such as a PLC controller) or control element. The control unit may be disposed at a suitable position of the linear-to-rotating device 100. For example, the control unit may be mounted on the mask motion stage. In other examples, the control unit may also be mounted at a suitable position other than the mask motion stage.

[0044] The preset accuracy requirement may be to require that the angle difference between the actual position of the mask and the target position is less than a certain threshold. For example, the preset accuracy requirement may be to require that the angle difference is less than 1 urad (microradian). In actual implementation, those skilled in the art may set different accuracy requirements according to actual conditions.

[0045] In some embodiments of the present invention, the linear motion module has a minimum step distance, and the mask motion stage rotates a minimum step angle when the linear motion module moves the minimum step distance, wherein the minimum step angle meets a preset accuracy requirement. For example, assuming that the preset accuracy requirement requires the angle difference to be less than 1 urad, when the linear motion module moves the minimum step distance, the angle at which the mask motion stage rotates will be less than 1 urad.

[0046] Figure 2 A perspective view of a linear motion module according to an embodiment of the present invention is shown.

[0047] As shown in the figure, the linear motion module includes a motor, a transmission screw, a tension spring, and a thrust bearing. In addition, Figure 2 Also shown is an adapter that fits the thrust bearing of the linear motion module.

[0048] like Figure 2As shown, the motor includes a stator part and a mover part, wherein the transmission screw is connected between the stator part and the mover part. In some embodiments of the present invention, the motor can be a stepper motor. In some other embodiments, the motor can also be a servo motor.

[0049] When the motor is running, it drives the transmission screw, thereby moving the mover part along the horizontal longitudinal direction (X-axis direction). In various embodiments of the present invention, the linear motion module performs linear motion in the X-axis direction, and the mask template motion stage performs rotational motion in the XY plane. In the present invention, the moving direction of the motor mover part (that is, the moving direction of the linear motion module) is defined as the horizontal longitudinal direction (also referred to as the X-axis direction herein), and the direction perpendicular to the horizontal longitudinal direction in the XY plane is defined as the horizontal transverse direction (also referred to as the Y-axis direction herein). It should be noted that the definitions of horizontal transverse direction and horizontal longitudinal direction are relative concepts. In different implementations, the definitions of horizontal transverse direction and horizontal longitudinal direction may be reversed.

[0050] One end of the tension spring is connected to the adapter, and the other end is connected to the mover part of the motor.

[0051] When the motor moves in the horizontal longitudinal direction ( Figure 2 When the thrust bearing pushes the adapter, the mask plate moving table rotates counterclockwise. When the motor moves in the horizontal longitudinal direction ( Figure 2 The tension spring pulls the adapter, and the mask plate moving platform rotates clockwise.

[0052] In some implementations, the thrust bearing can also be replaced by a thrust ball. In such implementations, there is sliding friction between the thrust ball and the adapter. In contrast, there is rolling friction between the thrust bearing and the adapter. Since the effect of sliding friction is lower than rolling friction, a thrust bearing is used in a preferred implementation.

[0053] In the present invention, for the convenience of explanation, the positive movement of the movable part along the horizontal longitudinal direction (i.e., the linear motion module moves forward along the horizontal longitudinal direction) and the counterclockwise rotation of the mask plate moving stage are regarded as positive movement, while the reverse movement of the movable part along the horizontal longitudinal direction (i.e., the reverse movement of the linear motion module along the horizontal longitudinal direction) and the clockwise rotation of the mask plate moving stage are regarded as reverse movement. It should be noted that the definition of positive movement and reverse movement is only exemplary and not restrictive. In actual implementation, those skilled in the art may define positive movement and reverse movement in different ways.

[0054] Different from the linear module in the prior art that moves in the vertical direction, the linear motion module of the present invention moves in the horizontal direction. Therefore, when the linear motion is converted into the rotational motion at the microscopic level, the deviation of the calculated rotation angle is reduced, thereby improving the accuracy of the rotation positioning.

[0055] In order to better understand the linear motion module, Figure 3 A cross-sectional view of a linear motion module is shown.

[0056] Specifically, Figure 3 The adapter, tension spring, thrust bearing and mover parts are shown in FIG.

[0057] As shown in the figure, the thrust bearing is always in contact with one side of the adapter without gap, and has a gap with the other side of the adapter. In the present invention, the side of the adapter that contacts the thrust bearing is also referred to as the front side of the adapter ( Figure 3 The side of the adapter that does not contact the thrust bearing is also called the reverse side of the adapter ( Figure 3 left side is shown in the middle).

[0058] In various embodiments of the present invention, the thrust bearing is always in contact with the front face of the adapter by a tension spring, one end of which is connected to the adapter and the other end of which is connected to the mover part of the motor.

[0059] Through the tension spring, the thrust bearing and the front face of the adapter can be kept in close contact during the counterclockwise and clockwise movement of the mask plate motion stage, eliminating the return clearance, thereby improving the rotation positioning accuracy. In addition, the contact between the thrust bearing and the adapter is surface-to-surface contact, with a large contact area, which further improves the rotation positioning accuracy compared to the existing technical solutions.

[0060] Figure 4 A schematic diagram of eliminating the return clearance between a thrust bearing and an adapter according to an embodiment of the present invention is shown.

[0061] When the thrust bearing of the mover part moves in the horizontal longitudinal positive direction, since the adapter and the mask plate moving platform are relatively fixedly installed, the thrust bearing pushes the mask plate moving platform to rotate counterclockwise, and at the same time, the contact surface of the thrust bearing and the adapter has lateral sliding, that is, the linear rotation operation is realized. As shown in the figure, when the thrust bearing pushes the adapter in the positive direction, the two always keep in contact. Specifically, the contact surface (front) of the thrust bearing and the adapter always keeps in close contact.

[0062] When the mask plate moving stage moves clockwise around the rotating bearing, the moving part moves in the reverse direction along the longitudinal direction. Due to the need to maintain high-precision movement, there should be no gap during the reverse movement, that is, there should be no return gap. Therefore, the thrust bearing needs to keep in contact with the adapter at all times.

[0063] However, due to the processing errors of the parts, the front and back sides of the adapter cannot be guaranteed to be in microscopic contact with the thrust bearing under the existing processing technology, and it is impossible to ensure that the thrust bearing and the back side of the mask adapter are always in contact when reversing. In addition, if the distance between the front and back sides is too large, there will be a gap, affecting the return accuracy, and if the distance is too small, the thrust bearing may not be able to fit in, or even if it can fit in, the friction is very large, affecting the effect of linear rotation.

[0064] To this end, the present application designs the thrust bearing to always be in contact with the front side of the adapter and to always maintain a certain processing gap with the back side. In order to solve the accuracy problem caused by the return gap, a tension spring is connected to the adapter, and the other end of the tension spring pulls the mover part to tightly pull the thrust bearing and the front side of the adapter together. In this way, whether the mask template moving platform moves counterclockwise or clockwise, it can be ensured that the thrust bearing and the front side of the adapter remain in close contact. When the mask template moving platform moves clockwise, due to the gap between the thrust bearing and the back side of the adapter, when the mover part moves in the horizontal longitudinal direction, the transmission force does not push the adapter through the thrust bearing, but tightly pulls the adapter through the tension spring, driving the mask template moving platform to move clockwise. In such cases, the size of the tension of the tension spring needs to be calculated in the selection so that it is greater than the maximum force of clockwise movement. Preferably, the size of the tension of the tension spring can be greater than 1.5 times the maximum force of clockwise movement.

[0065] By arranging the tension spring as described above, it can be ensured that the thrust bearing is always tightly fitted with the adapter without any return clearance, regardless of whether it is moving in the forward or reverse direction.

[0066] Figure 5 A schematic diagram showing rotational positioning of a mask moving stage according to an embodiment of the present invention is shown.

[0067] When the mask motion stage is rotated by a small angle (e.g. Figure 5 The initial position A in the figure is rotated to the target position B). According to the calculus method, the distance L1 between the contact point of the thrust bearing at position A (the contact point with the adapter) and the center of rotation O, the distance L2 between the contact point of the thrust bearing at the target position B and the center of rotation O, and the movement distance X1 of the linear motion module can be approximately regarded as a right triangle. Therefore, the formula X / L=α can be used to obtain X=α*L. In this way, the corresponding movement distance of the linear motion module when the mask plate motion stage rotates by an angle of α can be calculated.

[0068] When the mask motion stage is rotated by a large angle (for example, from Figure 5The initial position A in the mask is rotated to the target position D). Since the thrust bearing can only move in a straight line, the position of the contact point between the thrust bearing and the adapter is constantly changing when the mask template motion stage rotates. Therefore, the triangle formed by the distance L1 between the contact point between the thrust bearing and the adapter at the initial position A and the center O, the distance L4 between the contact point between the thrust bearing and the adapter at the target position D and the center O, and the movement distance X2 of the linear motion module is no longer a right triangle. At this time, if the movement distance of the linear motion module is still calculated by treating L1, L4, and X2 as a right triangle, the calculation result will have a large error.

[0069] To this end, in the present invention, when the mask plate motion stage needs to rotate a larger angle, the approximate distance of the linear module movement from the initial position A to the target position D can be first calculated very roughly according to the above formula X=α*L. It should be noted that the calculated distance is only an approximate value and not an exact value. By moving the linear motion module by this approximate distance, the mask plate motion stage can be rotated by a larger angle. After a large range of angular movement, the mask plate motion stage arrives near the target position D (assuming it arrives at position C). At this time, the angle detection unit (for example, a grating ruler) can detect the angle difference between the actual position C and the target position D, and the value of the angle difference is very small relative to the angle difference between the initial position A and the target position D.

[0070] Subsequently, X is calculated again by differentiation based on the angular difference between the actual position C and the target position D (i.e., the distance the linear motion module needs to move when the mask plate motion stage rotates from position C to position D). After the linear motion module moves the corresponding distance, the mask plate motion stage performs a small angle rotation and moves closer to the target position D. At this time, the grating ruler detects the angular difference between the actual position of the mask plate and the target position again, and the value of this angular difference is smaller than the angular difference measured after the previous rotation.

[0071] The above method can be repeated many times to gradually perform a rotational motion with a smaller angle. The smaller the angle, the closer the triangle formed by the distance between the contact point of the thrust bearing at the initial position and the target position and the center of the circle and the movement distance of the linear motion module can be regarded as a right triangle, and the accuracy of the approach motion under differential is getting more and more accurate.

[0072] In some cases, a control error window may be pre-set, such as setting the accuracy to be within 1 urad. When the angle difference after multiple rotations meets the preset accuracy requirement (for example, the angle difference is less than 1 urad), the rotation positioning of the mask motion stage is completed and meets the accuracy requirement.

[0073] During the multiple rotational movements, the angle of the mask plate / mask plate motion stage needs to be continuously adjusted until the angle difference meets the preset accuracy requirement (for example, the angle difference is less than 1 urad). During the process of adjusting the angle of the mask plate, if the current actual position of the mask plate does not exceed the target position (that is, the previous rotation amplitude of the mask plate is too small so that the current actual angle of the mask plate is less than the target angle), then after calculating the distance that the linear motion module needs to move based on the angle difference, the linear motion module can be moved in the positive direction by the corresponding distance. In this way, the mask plate can be moved in the positive direction (rotated counterclockwise) to reduce the angle difference.

[0074] As an example, Figure 6 FIG. 1 shows a schematic diagram of adjusting the angle when the actual position of the mask does not exceed the target position. Figure 6 The initial position A, target position D and current actual position E1 of the mask are shown in FIG. As can be seen from the figure, the angle of the actual position E1 is smaller than the angle of the target position D. In this case, the mask needs to continue to move forward (rotate counterclockwise, such as Figure 6 The target position is approached by moving the linear motion module in the positive direction to reduce the angle difference. Therefore, the distance that the linear motion module needs to move can be calculated based on the angle difference, and the linear motion module is moved in the positive direction by the distance.

[0075] In the process of adjusting the mask angle, if the current actual position of the mask exceeds the target position (i.e., the mask previously rotated too much so that the current actual angle of the mask is greater than the target angle), then after calculating the distance that the linear motion module needs to move based on the angle difference, the linear motion module can be moved in the opposite direction by a corresponding distance. Thus, the mask can be moved in the opposite direction (clockwise rotation) to reduce the angle difference.

[0076] As an example, Figure 7 A schematic diagram showing the adjustment angle when the actual position of the mask exceeds the target position. Figure 7 In FIG. 1 , the initial position A, the target position D, and the current actual position E2 of the mask are shown. As can be seen from the figure, the angle of the actual position E2 is greater than the angle of the target position D. In this case, the mask needs to be moved in the opposite direction (rotated clockwise, such as Figure 7 The target position is approached by moving the linear motion module in the direction of the arrow in the middle to reduce the angle difference. Therefore, the distance that the linear motion module needs to move can be calculated based on the angle difference, and the linear motion module can be moved in the reverse direction by the distance.

[0077] In principle, as long as the movement distance of the linear motion module is subdivided accurately enough, the angle rotation can be made more accurate. For example, assuming that the lead of the transmission screw is 1 mm (that is, the transmission screw rotates 1 circle, and the linear movement of 1 mm is equal to 1000 um), the subdivision multiple of the motor and the driver is 100,000 times (1 pulse, 1 / 100,000 rotation, that is, the minimum step is 1 pulse, and the linear motion module moves 1 / 100,000*1000=0.01 um). Assuming that the distance L between the thrust bearing and the rotation center is designed to be 0.2m, according to the formula 0.01 / 0.2=0.05 urad, the theoretical minimum step angle is 0.05 urad. This greatly improves the accuracy of the rotation angle compared to the existing technology. For positioning accuracy of about 1 urad, the minimum step angle of 0.05 urad fully meets the accuracy requirements.

[0078] Figure 8 A schematic scheme for controlling the rotational motion of a mask moving stage according to an embodiment of the present invention is shown.

[0079] like Figure 8 As shown, the host computer may send instructions to inform the PLC controller of the angle at which the mask moving stage needs to rotate.

[0080] Specifically, a rotation angle instruction may be input into the host computer, which then sends the instruction to the PLC controller.

[0081] In some implementations, the instruction may indicate the target position (ie, target angle) that the mask motion stage needs to reach. After receiving the instruction, the PLC controller may calculate the angle that the mask motion stage needs to rotate according to the current actual position (current angle) of the mask motion stage.

[0082] In some other implementations, the instruction may directly indicate the angle by which the mask moving stage is required to rotate from the current position.

[0083] The PLC controller can calculate the corresponding distance that the linear motion module needs to move according to the angle that the mask plate motion stage needs to rotate, and command the linear motion module to move the corresponding distance (for example, by sending a pulse signal). The linear motion of the linear motion module can drive the mask plate motion stage to perform rotational motion.

[0084] In some implementations, after the linear motion module moves a corresponding distance, the grating ruler can detect the deviation between the actual position of the mask and the target position (for example, the angle difference between the actual angle and the target angle) and feed the deviation back to the PLC controller. In other implementations, the grating ruler can feed back the actual position of the mask. The PLC controller can calculate the deviation between the actual position of the mask and the target position based on this.

[0085] If the deviation between the actual position of the mask and the target position does not meet the accuracy requirement, the PLC controller can determine the distance that the linear motion module needs to continue to move based on the deviation, and command the linear motion module to move the corresponding distance.

[0086] After the linear motion module moves a corresponding distance, the deviation between the actual position of the mask and the target position at this time can be calculated again to determine whether the deviation meets the accuracy requirement.

[0087] After one or more movements of the linear motion module, the deviation between the actual position of the mask and the target position can meet the accuracy requirement (for example, the angle difference between the actual angle and the target angle is less than a preset threshold). At this point, the rotation positioning of the mask motion stage is completed. Figure 8 The control scheme can make the rotational motion of the mask plate motion stage meet the preset accuracy requirements.

[0088] Fig. 9 A flow chart of a method 900 for controlling the rotational motion of a mask moving stage using a linear-to-rotation device according to an embodiment of the present invention is shown.

[0089] like Fig. 9 As shown, method 900 starts at step 905. At step 905, a mask is placed on a mask moving stage, wherein the center of the mask coincides with the center of the mask moving stage.

[0090] By aligning the center of the mask with the center of the mask moving stage, the mask moving stage and the mask can rotate around the same center, and the rotation angle of the mask moving stage is the rotation angle of the mask. Therefore, in the context of the present invention, the position / angle of the mask moving stage can be equivalent to the position / angle of the mask.

[0091] In step 910, an initial angle difference between an initial position of the mask motion stage and a target position is determined.

[0092] In some implementations, a target position can be received and an initial angular difference can be determined by comparison with an initial position.

[0093] In some other implementations, the angle that the mask moving stage needs to rotate (ie, the initial angle difference between the initial position and the target position) may be directly received.

[0094] In step 915, the distance that the linear motion module needs to move is determined according to the initial angle difference.

[0095] In some examples, the distance to move can be determined by the following formula:

[0096] X = α*L

[0097] Wherein, X represents the distance that the linear motion module needs to move, α represents the initial angle difference, and L represents the distance between the thrust bearing and the rotation center of the mask plate motion stage.

[0098] In step 920, the linear motion module is made to perform linear motion to drive the mask plate motion stage to perform rotational motion until the linear motion module moves a corresponding distance.

[0099] Specifically, the motor of the linear motion module can drive the linear motion module to perform linear motion. When it is detected that the linear motion module has moved a corresponding distance, the motor stops moving to make the linear motion module stationary.

[0100] At step 925, the actual angular difference between the actual position of the mask and the target position is determined.

[0101] For example, after the linear motion module moves a corresponding distance and comes to rest, the actual angle difference between the actual position of the mask and the target position can be determined by an angle detection unit (eg, a grating scale, a magnetic scale, etc.).

[0102] In step 930, it is determined whether the actual angle difference meets the preset accuracy requirement.

[0103] For example, the preset accuracy requirement may be that the actual angle difference between the actual position of the mask and the target position is less than 1urad. Thus, if the angle difference is less than 1urad, it can be determined that the actual angle difference meets the preset accuracy requirement, otherwise it can be determined that the actual angle difference does not meet the preset accuracy requirement.

[0104] If the actual angle difference does not meet the preset accuracy requirement (the output of decision block 930 is “No”), the distance that the linear motion module needs to move is determined according to the actual angle difference ( 935 ).

[0105] In some examples, the distance to move can be determined by the following formula:

[0106] X = α*L

[0107] Among them, X represents the distance that the linear motion module needs to move, α represents the actual angle difference, and L represents the distance between the thrust bearing and the rotation center of the mask plate motion stage.

[0108] Subsequently, steps 920 to 935 may be repeated until the actual angle difference meets the preset accuracy requirement.

[0109] In the process of repeating steps 920 to 935 so that the actual angle difference meets the preset accuracy requirement, the linear motion module needs to be moved once or multiple times, and the distance that the linear motion module needs to move next time is determined according to the value of the actual angle difference after each movement. As described above, in this process, the movement direction of the linear motion module can be determined according to the relationship between the actual position and the target position (whether the actual position exceeds the target position).

[0110] If the actual angle difference meets the preset accuracy requirement (the output of decision block 930 is "yes"), it can be considered that the mask plate motion stage has been positioned to the target position with the required accuracy. At this time, the motor can be stopped (940) to keep the linear motion module stationary, and the motor can be kept at a constant torque to prevent the mask plate motion stage from shaking (945). At this point, method 900 ends.

[0111] The technical solution of the present invention uses a linear motion module that performs linear motion in the X-axis direction as a driving component to push the mask plate motion stage to perform rotational motion in the XY plane, thereby improving the calculation accuracy of the rotation angle during linear rotation. At the same time, the moving distance of the linear motion module is gradually adjusted by the angle difference between the actual position of the mask plate and the target position, thereby achieving high-precision positioning of the linear rotation. In addition, by keeping the thrust bearing and the adapter in close contact at all times, the return gap is eliminated during the movement of the mask plate motion stage, and the contact between the thrust bearing and the adapter is surface-to-surface contact, with a large contact area, which further improves the rotation positioning accuracy.

[0112] The detailed description described above in conjunction with the accompanying drawings describes examples and does not represent all examples that can be implemented or fall within the scope of the claims. The terms "example" and "exemplary" when used in this specification mean "used as an example, instance or illustration" and do not mean "better or better than other examples".

[0113] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, use of these phrases may refer to more than just one embodiment. Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0114] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the universal principles defined herein may be applied to other aspects. Therefore, the claims are not intended to be limited to the aspects shown herein, but should be granted the full scope consistent with the claims in language, wherein the singular reference to the elements is not intended to mean "there is and only one", but "one or more", unless otherwise specifically stated. Unless otherwise specifically stated, the term "some" refers to one or more. The elements of the various aspects described throughout the present invention are all structurally and functionally equivalent schemes currently or hereafter known to those of ordinary skill in the art and are expressly incorporated herein by reference, and are intended to be covered by the claims.

[0115] It should also be noted that these embodiments may be described as a process depicted as a flow chart, flow diagram, structure diagram, or block diagram. Although the flow chart may describe the operations as sequential processes, many of these operations can be performed in parallel or concurrently. In addition, the order of these operations can be rearranged.

[0116] Although various embodiments have been illustrated and described, it should be understood that the embodiments are not limited to the precise configuration and components described above. Various modifications, substitutions and improvements obvious to those skilled in the art may be made in the arrangement, operation and details of the devices disclosed herein without departing from the scope of the claims.

Claims

1. A linear-to-rotating device for a lithography apparatus, comprising: A mask plate moving platform, used for carrying the mask plate, wherein the mask plate moving platform can perform rotational motion; A linear motion module, used to drive the mask plate motion stage to perform rotational motion by linear motion, the linear motion module comprising a thrust bearing, a motor, a transmission screw, and a tension spring, wherein the motor drives the transmission screw and comprises a stator part and a mover part, the thrust bearing is mounted on the mover part, and wherein one end of the tension spring is connected to an adapter and the other end is connected to the mover part of the motor; An adapter, the adapter being arranged on the mask plate moving platform, wherein the thrust bearing is kept in close contact with one side of the adapter during the rotational movement of the mask plate moving platform, wherein the thrust bearing is kept in close contact with one side of the adapter by the tension spring; an angle detection unit, configured to detect an angle difference between an actual position of the mask and a target position; and The control unit is used to adjust the moving distance of the linear motion module according to the angular difference between the actual position of the mask plate and the target position so that the angular difference meets the preset accuracy requirement.

2. The device according to claim 1, further comprising a rotary bearing, the rotary bearing being located at the center of the mask moving stage and the mask moving stage performing a rotary motion around the rotary bearing, and wherein, The angle detection unit is adhered to the rotary bearing.

3. The device according to claim 1, wherein: The motor is a stepper motor or a servo motor.

4. The device according to claim 1, wherein: The mover portion of the motor moves along the X-axis direction, and When the moving part moves along the positive direction of the X-axis, the thrust bearing pushes the adapter, and the mask plate moving stage rotates counterclockwise in the XY plane, and When the movable part moves in the opposite direction along the X-axis, the tension spring pulls the adapter, and the mask plate moving stage performs a clockwise rotation movement in the XY plane.

5. The device according to claim 1, wherein: The thrust bearing is decoupled from the adapter in the Y-axis direction.

6. The device according to claim 1, wherein: The angle detection unit includes a grating scale or a magnetic scale.

7. The device according to claim 1, wherein: The linear motion module has a minimum step distance, and the mask plate motion stage rotates a minimum step angle when the linear motion module moves the minimum step distance, wherein the minimum step angle meets the preset accuracy requirement.

8. A method for controlling the rotational motion of a mask plate motion stage using the device according to any one of claims 1 to 7, comprising the following steps: S1: placing a mask plate on the mask plate moving stage, wherein the center of the mask plate coincides with the center of the mask plate moving stage; S2: Determine an initial angle difference between an initial position of the mask and a target position; S3: determining the distance that the linear motion module needs to move according to the initial angle difference; S4: causing the linear motion module to perform linear motion to drive the mask plate motion stage to perform rotational motion until the linear motion module moves a corresponding distance; S5: Determine whether the actual angle difference between the actual position of the mask and the actual angle difference between the target position meets the preset accuracy requirement; S6: if the actual angle difference does not meet the preset accuracy requirement, determining the distance that the linear motion module needs to move according to the actual angle difference; S7: Repeat steps S4 to S6 until the actual angle difference between the actual position of the mask and the target position meets the preset accuracy requirement.

9. The method according to claim 8, further comprising: When the actual angle difference between the actual position of the mask plate and the actual angle difference between the target position meets the preset accuracy requirement, the motor of the linear motion module stops moving and maintains a constant torque.

10. The method according to claim 8, wherein: Determining the distance that the linear motion module needs to move according to the initial angle difference or the actual angle difference further includes determining the distance that the linear motion module needs to move by the following formula: X = α*L Wherein, X represents the distance that the linear motion module needs to move, α represents the initial angle difference or the actual angle difference, and L represents the distance between the thrust bearing and the rotation center of the mask plate motion stage.

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