introduction

In the field of semiconductor manufacturing, wafer transfer is a crucial link, and its accuracy and stability directly affect the quality and production efficiency of chips. DD motors (Direct Drive Motors) have been widely used in semiconductor wafer transfer systems due to their advantages of high precision, high response speed, and low maintenance costs. However, during actual operation, the DD motor may generate vibrations, which not only affect the accuracy of wafer transmission but may also cause wafer damage and reduce production yield. Therefore, studying the vibration suppression technology of DD motors in semiconductor wafer transport has important practical significance.

Reasons for DD motor vibration

The reasons for the vibration generated by DD motors in semiconductor wafer transportation are multifaceted. From a mechanical structural perspective, rotor imbalance is one of the common factors. Due to limitations in manufacturing processes, the mass distribution of the rotor may be uneven, resulting in centrifugal force and vibration during rotation. In addition, wear, looseness, or improper installation of bearings can also cause vibration. As a key component supporting the rotor, the performance degradation of bearings will change the motion state of the rotor and generate additional vibrations.

Electrical factors cannot be ignored either. Current fluctuations can cause magnetic field instability, resulting in uneven electromagnetic force on the rotor and causing vibration. For example, instability of the power supply and faults in the drive circuit can cause current fluctuations. In addition, the imperfect motor control algorithm may also lead to vibration. If the control algorithm cannot respond to load changes and system disturbances in a timely and accurate manner, it will cause the output torque of the motor to be unstable, resulting in vibration.

External environmental factors can also affect the vibration of DD motors. Wafer transfer systems are typically located in complex industrial environments with various sources of vibration, such as vibrations from other equipment, ground vibrations, etc. These external vibrations will be transmitted to the DD motor through the mechanical structure, exacerbating its vibration.

Vibration suppression technology

Mechanical structure optimization

Optimizing the mechanical structure of DD motors is an important means of suppressing vibration. The vibration caused by rotor imbalance can be reduced by improving the dynamic balance accuracy of the rotor. By using advanced dynamic balance detection and calibration equipment, the rotor is precisely balanced to minimize centrifugal force during rotation. At the same time, optimize the design and selection of bearings, choose high-performance bearings, improve their load-bearing capacity and accuracy, and reduce bearing wear and looseness. In addition, elastic support structures such as rubber shock absorbers, air springs, etc. can be used to isolate the impact of external vibrations on the DD motor and reduce vibration transmission.

Electrical control optimization

In terms of electrical control, adopting advanced control algorithms can effectively suppress vibration. For example, adaptive control algorithms can automatically adjust control parameters based on the real-time operating status of the system, enabling the motor to maintain stable performance under different load conditions. Fuzzy control algorithms are based on fuzzy logic and do not require precise mathematical models, which can better cope with system uncertainty and nonlinearity, and improve system robustness. In addition, current feedforward control technology is adopted to predict in advance the impact of load changes on current, and adjust current output in a timely manner to reduce vibration caused by current fluctuations.

In order to improve the stability of the current, high-performance driving power supplies and filtering circuits can also be used. The driving power supply should have good voltage and current stabilization performance to ensure stable and reliable current supply to the DD motor. The filtering circuit can filter out high-frequency noise and interference signals in the power supply, reducing the impact of current fluctuations on the motor.

External vibration isolation

External vibration isolation measures can be taken to address vibrations caused by external environmental factors. On the basis of installing the DD motor, use vibration isolation pads or isolators to isolate the motor from the ground or other vibration sources. Vibration isolation pads are usually made of materials such as rubber and springs, and have good shock absorption performance. Isolators can be designed based on vibration frequency and amplitude to effectively isolate different types of vibrations. In addition, in the layout design of wafer transfer systems, efforts should be made to avoid proximity to other vibration sources and reduce external vibration interference.

Sensor feedback and active control

The use of sensor feedback and active control technology is also an important method for suppressing vibration. Install acceleration sensors, displacement sensors, etc. on DD motors to monitor the vibration status of the motor in real time. Feedback the vibration signal collected by the sensor to the control system, and the control system adjusts the control parameters of the motor based on the feedback signal to achieve active suppression of vibration. For example, when the vibration amplitude exceeds the set threshold, the control system can automatically adjust the current output, change the torque characteristics of the motor, and thereby reduce the vibration.

Practical application case analysis

Application of wafer handling robots

In semiconductor wafer handling robots, the DD motor serves as the core component driving the joints, and its vibration has a significant impact on the accuracy of wafer handling. A certain wafer handling robot adopts vibration suppression technology that combines mechanical structure optimization and electrical control optimization. In terms of mechanical structure, high-precision dynamic balance correction was carried out on the rotor, and an elastic support structure was adopted. In terms of electrical control, adaptive control algorithms and current feedforward control technology are adopted. Through these measures, the vibration amplitude of the wafer handling robot has been significantly reduced, and the positioning accuracy of wafer handling has reached ± 0.5 μ m, meeting the high-precision requirements of semiconductor manufacturing.

Application in wafer transfer track system

In the wafer transfer track system, the vibration of the DD motor can affect the stability of the wafer during the transfer process. A certain wafer transfer track system adopts external vibration isolation and sensor feedback and active control technology. By installing isolators and acceleration sensors, the vibration status of the DD motor can be monitored and adjusted in real time. After optimization, the vibration of the wafer during transportation has been effectively suppressed, and the stability of wafer transportation has been significantly improved, reducing scratches, damages, and other issues caused by vibration and improving the production yield of wafers.

conclusion

The vibration suppression technology of DD motor in semiconductor wafer transfer is the key to ensuring the accuracy and stability of wafer transfer. Through the comprehensive application of various technologies such as mechanical structure optimization, electrical control optimization, external vibration isolation, and sensor feedback and active control, the vibration amplitude of DD motors can be effectively reduced, and the quality and efficiency of wafer transfer can be improved. In practical applications, different combinations of vibration suppression techniques can be selected and adjusted according to specific application scenarios and requirements. With the continuous development of semiconductor manufacturing technology and the increasing demand for wafer transfer accuracy, the vibration suppression technology of DD motors will also continue to innovate and improve, providing strong support for the high-quality development of the semiconductor manufacturing industry.