Photomask clamping mechanism

Abstract

The invention discloses a photomask clamping mechanism in the field of semiconductor photomask clamping, the photomask clamping mechanism comprises an electric rotating clamping jaw with a rotating and displacement output end, symmetrically arranged extension rods and positioning jaws with V-shaped clamping grooves, at least one positioning jaw is connected with the extension rods through a force control unit, and the force control unit is configured to drive the V-shaped clamping grooves to rotate. In the process of driving the photomask to turn over, on the premise that the positioning claw always abuts against the photomask, the positive pressure acting on the photomask is reduced so as to absorb the contact stress caused by gravity vector switching. By dynamically adjusting the clamping pressure, the local accumulated stress originally under rigid constraint is correspondingly released, fretting wear caused by change of a gravity field in a high-pressure state is avoided, generation of dust particles is restrained from the mechanical source, and the technical problem that the yield is damaged due to friction powder falling in the integrated overturning process is solved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor photomask clamping, and more specifically to a photomask clamping mechanism. Background Technology

[0002] In semiconductor manufacturing processes, the orientation of the photomask directly determines its docking accuracy with the production equipment. Since the orientation requirements of the photomask pattern surface are different in storage and exposure states, a necessary step in automated production lines is the flipping operation.

[0003] The current common practice is to use the grippers of a handling robot for horizontal translation, and then have a separate flipping station handle the attitude switching. While this mode avoids the risks of gripping in dynamic postures, it significantly increases the equipment footprint and the frequency of material handover. In pursuit of higher production efficiency, integrating the flipping function into the handling gripper has become an industry trend. However, this integrated design faces stringent cleanliness challenges in practical applications.

[0004] Photomasks are typically secured by an interference fit or tight fit between the V-shaped grooves of the end grippers and the chamfered edges, relying on strong positive pressure to generate static friction for stability. However, during the process of the grippers rotating the photomask, the gravity vector relative to the clamping contact surface undergoes continuous dynamic switching, causing the force balance at the contact interface to be disrupted.

[0005] In traditional rigid clamping solutions, to absolutely prevent the photomask from falling off, the grippers typically maintain a constant and high clamping force, resulting in extremely high local stress in the contact area between the photomask and the grippers. When the gravitational component attempts to induce a slight displacement as the rotation angle changes, this high-strength rigid constraint prevents the local shear stress at the contact point from being flexibly released, leading to a high accumulation of stress at the microscopic interface.

[0006] Because the mechanical structure is not absolutely rigid and the gripper material (such as polymer) is elastic, the change in the gravitational field during the flipping process will cause "elastic breathing" or creep at the microscopic level.

[0007] Under such high pressure, any tiny stress adjustment that attempts to balance gravity will evolve into severe fretting wear, i.e., forced slippage of the contact surface under restricted conditions.

[0008] This "hard abrasion" effect, caused by the inability of stress to be released, can instantly lead to material fatigue and peeling at the contact interface, generating a large number of submicron-sized dust particles. These particles are easily dispersed and adsorbed onto the photomask surface under the airflow disturbance generated by the flipping action, becoming a hidden factor that damages the yield. Summary of the Invention

[0009] The purpose of this invention is to provide a photomask clamping mechanism to solve the problem that the contact stress cannot be released due to the switching of gravity vectors during the photomask flipping process, thus generating dust particles.

[0010] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution: A photomask clamping mechanism, comprising: An electric rotary gripper has a rotary output end and two displacement output ends that are movably disposed on the rotary output end and can move toward or away from each other. The extension rods are arranged in two sets symmetrically, and one end of each extension rod is fixedly connected to the corresponding displacement output end. There are two positioning claws, and each positioning claw is connected to the free end of a corresponding extension rod. A V-shaped groove is formed on the side of the positioning claw that contacts the photomask. At least one positioning claw is connected to the corresponding extension rod via a force control unit; The force control unit is configured to reduce the positive pressure exerted by the positioning claw on the photomask while maintaining constant contact between the positioning claw and the photomask during the process of the electric rotating gripper driving the photomask to rotate, so as to absorb the contact stress caused by the switching of the photomask's gravity vector.

[0011] Furthermore, the force control unit includes: A fixed bracket is attached to the extension rod. The floating seat is fixedly connected to the positioning claw, and the floating seat and the fixed bracket are connected by a straight-line guide mechanism; An electromagnetic actuation component is positioned between a fixed bracket and a floating base to generate a non-contact magnetic driving force to drive the positioning claw to contact the photomask. The controller is electrically connected to the electromagnetic actuation component and the electric rotary gripper. The controller adjusts the magnetic driving force according to the rotation state of the electric rotary gripper.

[0012] Furthermore, a spring is provided between the fixed bracket and the floating seat. The spring is configured to apply a basic clamping force toward the photomask to the positioning claw to maintain contact with the photomask when the electromagnetic actuation component is de-energized.

[0013] Furthermore, the electromagnetic actuation component is a voice coil motor, with its stator fixed to a fixed bracket and its mover fixed to a floating seat. The magnetic driving force generated by the voice coil motor is superimposed on the spring force through its stator to adjust the magnitude of the magnetic driving force or the basic clamping force.

[0014] Furthermore, the rotation output end of the electric rotary gripper is equipped with an angle sensor to detect its rotation. Based on the signal from the angle sensor, the force control unit reduces the positive pressure to achieve pressure reduction and force relief when it determines that the photomask is flipped.

[0015] Furthermore, a rectangular positioning block is fixedly provided at the rotating output end of the electric rotary gripper, and a transverse receiving groove is formed on the outer side of the rectangular positioning block. Two sets of horizontally distributed limiting slide grooves are symmetrically provided in the transverse receiving groove. The extension rod is L-shaped, with its short side sliding and nested in the corresponding limiting groove via a slider. The two displacement output ends pass through rectangular positioning blocks and are fixedly connected to the corresponding sliders.

[0016] Furthermore, the rectangular positioning block has a strip-shaped through hole through which two displacement output ends pass to connect the extension rod. The length of the strip-shaped through hole is greater than the maximum active stroke of the displacement output end.

[0017] Furthermore, the linear guide mechanism consists of two sets of miniature ball bearing guide posts and sleeves, which are symmetrical about the electromagnetic actuation component. One end of the guide post of the miniature ball bearing guide post and sleeve is fixedly connected to a positioning claw, and the sleeve of the miniature ball bearing guide post and sleeve is fixedly mounted on the extension rod. An elastic corrugated cover is provided between the exposed end of the miniature ball guide post and the connection between the positioning claw and the extension rod; The number of springs matches the number of miniature ball bearing guide posts and sleeves. The springs are sleeved outside the corresponding miniature ball bearing guide posts and are located inside the elastic bellows cover between the positioning claw and the extension rod.

[0018] Furthermore, a force sensor for detecting the spring's resistance is embedded in the extension rod at the position where it contacts the spring. The force sensor is electrically connected to the controller. The force sensor is ring-shaped, and the guide post of the miniature ball bearing guide sleeve passes through the central hole of the force sensor without contact.

[0019] Furthermore, the electric rotary gripper is fixedly mounted on a sliding base, and a translation component is connected to the outside of the sliding base.

[0020] The beneficial effects of this invention are: This mechanism dynamically reduces the normal pressure exerted by the positioning claw on the photomask during the flipping process by using a force control unit. Utilizing the flexible characteristics of magnetic driving force or elastic force compensation, when the photomask generates shear stress due to the switching of the gravity vector direction, the normal stress between the contact interfaces can be reduced by decreasing the normal pressure. This allows the local accumulated stress that was originally under rigid constraint to be released in accordance with the force, avoiding fretting wear caused by forced displacement compensation under high pressure, and suppressing the generation of dust particles from the mechanical source. Attached Figure Description

[0021] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0022] Figure 1 This is a three-dimensional structural diagram of an embodiment of the present invention; Figure 2 This is a schematic diagram of the clamping state of the positioning claw and the photomask according to an embodiment of the present invention; Figure 3 This is a planar structural cross-sectional view of the force control unit according to an embodiment of the present invention; Figure 4 for Figure 3 Enlarged schematic diagram of the structure at point A in the diagram; Figure 5 This is a three-dimensional structural breakdown diagram of an embodiment of the present invention. Figure 1 ; Figure 6 for Figure 5 Enlarged schematic diagram of the structure at point B in the diagram; Figure 7 This is a three-dimensional structural breakdown diagram of an embodiment of the present invention. Figure 2 ; Figure 8 for Figure 7 Enlarged schematic diagram of the structure at point C; The labels in the diagram represent the following: 1-Electric rotary gripper; 1a-Rotation output end; 1b-Displacement output end; 2-Extension rod; 2a-Fixed bracket; 3-Positioning gripper; 3a-V-shaped groove; 3b-Floating seat; 4-Spring; 5-Voice coil motor; 6-Rectangular positioning block; 6a-Transverse receiving groove; 6b-Limiting slide groove; 6c-Strip through hole; 7-Force sensor; 8-Miniature ball bearing guide post and guide sleeve; 8a-Guide post; 8b-Guide sleeve; 9-Elastic corrugated cover; 10-Sliding base. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] This embodiment provides a photomask clamping mechanism, which aims to solve the problem that the contact stress cannot be released due to the switching of gravity vectors during the photomask flipping process, thus generating dust particles.

[0025] Specifically, refer to Figures 1 to 8 The photomask clamping mechanism includes an electrically driven rotary gripper 1, which has a rotary output end 1a and two displacement output ends 1b movably mounted on the rotary output end 1a and capable of moving towards or away from each other. In this embodiment, the electrically driven rotary gripper 1 is a readily available general-purpose automation component. This component provides rotational freedom through an internally integrated rotary motor and drives the two displacement output ends 1b to perform synchronous linear reciprocating motion through a built-in lead screw and nut mechanism or gear and rack mechanism. The rotational angle accuracy, displacement control stroke, and output torque adjustment of this component are all mature and well-known technologies in the field, and those skilled in the art can directly purchase them from the market according to actual process requirements. Therefore, its specific internal mechanical structure will not be described in detail.

[0026] Two sets of symmetrically arranged extension rods 2 are fixedly connected to the corresponding displacement output ends 1b, and two positioning claws 3 are respectively connected to the free ends of the corresponding extension rods 2. A V-shaped groove 3a is formed on the side of the positioning claw 3 that contacts the photomask.

[0027] At least one positioning claw 3 is connected to the corresponding extension rod 2 via a force control unit. The force control unit is configured to reduce the positive pressure exerted by the positioning claw 3 on the photomask while keeping the positioning claw 3 in constant contact with the photomask during the process of the electric rotating gripper 1 driving the photomask to rotate, so as to absorb the contact stress caused by the switching of the photomask's gravity vector.

[0028] By actively reducing the positive pressure, the mechanism can allow the photomask to release locally accumulated shear stress at the microscopic level when the direction of the gravitational field changes, thereby avoiding severe "hard grinding" fretting wear under high pressure and suppressing the generation of dust particles from the source.

[0029] Since the gravitational component experienced by the photomask during the flipping process changes dynamically with the rotation angle, it is difficult to achieve precise timing of force release if the rotation attitude cannot be sensed in real time.

[0030] To this end, an angle sensor is installed at the rotation output end 1a of the electric rotary gripper 1 to detect its rotation. The controller in the force control unit determines when the photomask flips by reducing the positive pressure to achieve pressure reduction and force relief based on the signal from the angle sensor. This attitude feedback-based control method ensures that the pressure adjustment and the switching of the gravity vector are synchronized.

[0031] In the actual control logic of this organization, the force control unit adopts a preset two-stage pressure switching strategy to balance the handling efficiency and the cleanliness of the flipping. Specifically, the controller has pre-stored the target values ​​of the first clamping force F1 and the second clamping force F2. These two values ​​are pre-determined based on the photomask quality, handling acceleration and material friction coefficient.

[0032] When the electric rotary gripper 1 is in the normal horizontal transport stage, the controller drives the electromagnetic actuator to output the maximum set current, so that the positive pressure of the positioning gripper 3 on the photomask is maintained at a high level of the first clamping force F1, ensuring that the photomask does not undergo relative displacement under the action of the inertial force of high-speed translation. When the angle sensor detects that the rotation output terminal 1a has started to perform a flipping action, the controller immediately adjusts the current to a low threshold, reducing the positive pressure to a lower level of the second clamping force F2. At this time, the value of the second clamping force F2 is configured such that, under the premise of satisfying dynamic balance, the maximum static friction force generated is still greater than the gravitational component of the photomask sliding down the side wall of the V-shaped slot 3a during the flipping process, thereby minimizing the positive pressure on the contact surface while ensuring the safety baseline of preventing the photomask from falling off.

[0033] To further support the aforementioned dynamic force-relieving logic and suppress dust generation at its source, the interface between the positioning claw 3 and the photomask has been optimized using materials science. The surface of the V-shaped groove 3a of the positioning claw 3 is made of high-performance clean polymer materials such as polyetheretherketone (PEEK) or polytetrafluoroethylene (PTFE). These materials have extremely low coefficients of friction and excellent self-lubricating properties. After the positive pressure is switched to the second clamping force F2 through the pressure reduction logic, the flexible contact surface of the PEEK or PTFE material can adapt to the micro-displacement generated by the gravity vector switching, so that the shear stress that would have evolved into "hard grinding" under rigid high pressure is transformed into a small amount of elastic deformation or low-energy micro-slippage.

[0034] This synergistic effect of material and force significantly reduces the number of submicron particles generated at the contact interface during the flipping process, greatly improving production yield.

[0035] At the specific structural level for achieving force control, in order to enable the positioning claw 3 to make slight elastic retraction or pressure compensation relative to the extension rod 2, the force control unit includes a fixed bracket 2a fixed to the extension rod 2 and a floating seat 3b fixed to the positioning claw 3. The floating seat 3b and the fixed bracket 2a are connected by a straight-line guide mechanism.

[0036] An electromagnetic actuation component is provided between the fixed bracket 2a and the floating seat 3b to generate a non-contact magnetic driving force to drive the positioning claw 3 to abut against the photomask.

[0037] The controller is electrically connected to the electromagnetic actuation component and the electric rotary gripper 1. The controller adjusts the magnetic driving force according to the rotation state of the electric rotary gripper 1. The non-contact magnetic driving force can provide extremely high force control accuracy and response speed.

[0038] Considering that electromagnetic drive relies entirely on power supply, a power outage may cause the clamping force to disappear instantly. To eliminate this potential hazard, a spring 4 is provided between the fixed bracket 2a and the floating seat 3b. The spring 4 is configured to apply a basic clamping force toward the photomask to the positioning claw 3 so as to maintain contact with the photomask when the electromagnetic actuation component is de-energized. During normal operation, the force generated by the electromagnetic actuation component and the force of the spring 4 are superimposed to each other to jointly construct an adjustable flexible contact interface.

[0039] To further improve the linearity and sensitivity of the force adjustment, the electromagnetic actuation component uses a voice coil motor 5. The stator of the voice coil motor 5 is fixed to the fixed bracket 2a, and the mover is fixed to the floating seat 3b. The magnetic driving force generated by the voice coil motor 5 is superimposed on the elastic force of the spring 4 through the stator to adjust the magnitude of the magnetic driving force or the basic clamping force. The unique zero hysteresis and zero backlash characteristics of the voice coil motor 5 enable the mechanism to achieve millisecond-level pressure switching, accurately responding to every degree angle change during the flipping process.

[0040] To ensure that the positioning claw 3 does not deflect or jam when reciprocating to adjust the pressure, the linear guide mechanism adopts two sets of miniature ball bearing guide posts and sleeves 8 symmetrically arranged about the electromagnetic actuation components. One end of the guide post 8a of the miniature ball bearing guide post and sleeve 8 is fixedly connected to the positioning claw 3, and the sleeve 8b is fixedly set to the extension rod 2. Since precision mechanical movement is inevitably accompanied by friction, in order to prevent the micro-debris generated by the friction of the guide post 8a and sleeve 8b from escaping into the clean room, an elastic corrugated cover 9 is provided between the exposed end of the miniature ball bearing guide post and sleeve 8 and the connection between the positioning claw 3 and the extension rod 2.

[0041] The number of springs 4 matches the number of miniature ball guide post sleeves 8. The springs 4 are sleeved outside the guide post 8a of the corresponding miniature ball guide post sleeve 8 and are located inside the elastic corrugated cover 9 between the positioning claw 3 and the extension rod 2. The elastic corrugated cover 9 completely seals the friction pair and springs 4 inside, ensuring the cleanliness of the external working environment.

[0042] Because mechanical parts have manufacturing tolerances and spring 4 may experience fatigue degradation after long-term use, relying solely on current control may not accurately determine the actual force acting on the photomask. Therefore, a force sensor 7 is embedded in the extension rod 2 at the position where it contacts spring 4 to detect the force of the spring 4. This force sensor 7 is electrically connected to the controller.

[0043] The force sensor 7 is ring-shaped, and the guide post 8a of the miniature ball bearing guide sleeve 8 passes through the center hole of the force sensor 7 without contact. This non-contact through-hole design avoids interference of the movement of the guide post 8a with the force measurement result.

[0044] Based on the feedback signal from the force sensor 7, the controller adjusts the electromagnetic actuation component to output a first clamping force F1 during the initial clamping phase and a second clamping force F2, which is less than the first clamping force F1, during the flipping phase, thereby achieving closed-loop precise torque control.

[0045] Throughout the dynamic pressure regulation process, force sensor 7 provides real-time closed-loop safety assurance for the mechanism. The controller continuously monitors the resultant force signal fed back by force sensor 7 and compares it with the preset safety threshold F. safe Perform real-time comparison.

[0046] If, during the flipping process, system fluctuations or electromagnetic anomalies cause the actual pressure to fall below F, which is sufficient to counteract the gravitational downward component, then... safe The controller will immediately trigger the error reporting logic and drive the voice coil motor 5 to increase the output torque to prevent the photomask from accidentally slipping off.

[0047] In addition, since spring 4 always provides basic clamping force, even in extreme power failure situations, the mechanism can still maintain contact with the photomask by relying on the mechanical energy of spring 4. Combined with the support of low-friction material, it ensures that the material does not shift under static conditions, thus achieving dual protection of active friction reduction and passive drop prevention.

[0048] In terms of overall mechanical strength and installation accuracy, in order to support the long extension rod 2 and ensure stability during large stroke movement, a rectangular positioning block 6 is fixedly provided on the rotating output end 1a of the electric rotating gripper 1. A transverse receiving groove 6a is formed on the outer side of the rectangular positioning block 6, and two sets of horizontally distributed limiting grooves 6b are symmetrically provided in the transverse receiving groove 6a.

[0049] The extension rod 2 is L-shaped, with its short side slidingly nested in the corresponding limiting groove 6b via a slider. The two displacement output ends 1b pass through the rectangular positioning block 6 and are fixedly connected to their respective sliders. This slider-groove connection effectively absorbs eccentric loads during the flipping process. Simultaneously, the rectangular positioning block 6 has a strip-shaped through hole 6c through which the two displacement output ends 1b pass to connect the extension rod 2. The length of the strip-shaped through hole 6c is greater than the maximum travel of the displacement output ends 1b. Furthermore, a side cover plate is provided on the outer side of the transverse receiving groove 6a to prevent the short side of the extension rod 2 from detaching and falling out of the limiting groove 6b.

[0050] In order to enable the transfer of photomasks between different workstations, the photomask clamping mechanism is also equipped with a sliding base 10. The electric rotating gripper 1 is fixedly set on the sliding base 10, and a translation component is connected to the sliding base 10, so that the entire mechanism has the ability to move freely in space.

[0051] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its spirit and scope of protection, and such modifications or equivalent substitutions should also be considered as falling within the scope of protection of the embodiments of the present invention.

Claims

1. A photomask clamping mechanism, characterized in that, include: An electric rotary gripper (1) has a rotary output end (1a) and two displacement output ends (1b) movably disposed on the rotary output end (1a) and capable of moving toward or away from each other. Two sets of extension rods (2) are symmetrically arranged, and one end of each extension rod (2) is fixedly connected to the corresponding displacement output end (1b). There are two positioning claws (3), and each positioning claw (3) is connected to the free end of a corresponding extension rod (2). A V-shaped groove (3a) is formed on the side of the positioning claw (3) that contacts the photomask. At least one of the positioning claws (3) is connected to the corresponding extension rod (2) via a force control unit. The force control unit is configured to reduce the positive pressure exerted by the positioning claw (3) on the photomask during the process of the electric rotating gripper (1) driving the photomask to flip, while keeping the positioning claw (3) in constant contact with the photomask, so as to absorb the contact stress caused by the switching of the photomask gravity vector.

2. The photomask clamping mechanism according to claim 1, characterized in that, The force control unit includes: A fixed bracket (2a) is fixedly connected to the extension rod (2); A floating seat (3b) is fixedly connected to the positioning claw (3), and the floating seat (3b) and the fixed bracket (2a) are connected by a straight-line guide mechanism; An electromagnetic actuation component is disposed between the fixed bracket (2a) and the floating seat (3b) to generate a non-contact magnetic driving force to drive the positioning claw (3) to abut against the photomask; The controller is electrically connected to the electromagnetic actuation component and the electric rotating gripper (1), and the controller adjusts the magnetic driving force according to the rotation state of the electric rotating gripper (1).

3. The photomask clamping mechanism according to claim 2, characterized in that, A spring (4) is provided between the fixed bracket (2a) and the floating seat (3b), the spring (4) being configured to apply a basic clamping force toward the photomask to the positioning claw (3) to maintain contact with the photomask when the electromagnetic actuation assembly is de-energized.

4. The photomask clamping mechanism according to claim 2, characterized in that, The electromagnetic actuation component is a voice coil motor (5), whose stator is fixed to the fixed bracket (2a) and whose mover is fixed to the floating seat (3b). The magnetic driving force generated by the voice coil motor (5) is superimposed on the elastic force of the spring (4) through its stator to adjust the magnitude of the magnetic driving force or the basic clamping force.

5. The photomask clamping mechanism according to claim 1, characterized in that, The rotation output end (1a) of the electric rotating gripper (1) is provided with an angle sensor for detecting its rotation. The force control unit reduces the positive pressure to achieve pressure reduction and force relief when it determines that the photomask is flipped, based on the signal from the angle sensor.

6. The photomask clamping mechanism according to claim 1, characterized in that, The rotating output end (1a) of the electric rotating gripper (1) is fixedly provided with a rectangular positioning block (6). A transverse receiving groove (6a) is formed on the outer side of the rectangular positioning block (6). Two sets of horizontally distributed limiting grooves (6b) are symmetrically provided in the transverse receiving groove (6a). The extension rod (2) is L-shaped, and its short side is slidably nested in the corresponding limiting groove (6b) through a slider. The two displacement output ends (1b) pass through the rectangular positioning block (6) and are fixedly connected to the corresponding slider.

7. The photomask clamping mechanism according to claim 6, characterized in that, The rectangular positioning block (6) has a strip-shaped through hole (6c) through which the two displacement output ends (1b) pass to connect the extension rod (2). The length of the strip-shaped through hole (6c) is greater than the maximum travel of the displacement output end (1b).

8. A photomask clamping mechanism according to any one of claims 2 to 4, characterized in that, The linear guide mechanism is a miniature ball bearing guide post and sleeve (8), which consists of two sets and is symmetrical about the electromagnetic actuation component. One end of the guide post (8a) of the miniature ball bearing guide post and sleeve (8) is fixedly connected to the positioning claw (3), and the sleeve (8b) of the miniature ball bearing guide post and sleeve (8) is fixedly set on the extension rod (2). An elastic corrugated cover (9) is provided between the exposed end of the miniature ball bearing guide sleeve (8) and the connection between the positioning claw (3) and the extension rod (2). The number of springs (4) matches the number of miniature ball bearing guide sleeves (8). The springs (4) are sleeved on the guide post (8a) of the corresponding miniature ball bearing guide sleeve (8) and are located inside the elastic corrugated cover (9) between the positioning claw (3) and the extension rod (2).

9. A photomask clamping mechanism according to claim 8, characterized in that, A force sensor (7) for detecting the resistance force of the spring (4) is embedded on the extension rod (2) at the position where it contacts the spring (4). The force sensor (7) is electrically connected to the controller. The force sensor (7) is in the shape of a ring. The guide post (8a) of the miniature ball bearing guide sleeve (8) passes through the center hole of the force sensor (7) without contact.

10. A photomask clamping mechanism according to claim 1, characterized in that, The electric rotating gripper (1) is fixedly mounted on a sliding base (10), and a translation component is connected to the sliding base (10).

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