Study Of Sensor For Measuring Micro-Force And Stick-Slip On Contact Surface Of Wafer Transmission

As an essential equipment of integral circuit (IC) manufacturing, wafer transfer robot takes a very important mission of transferring wafer precisely, fast and steadily from one position to another. End effector, which is an important part of wafer transfer robot, has a great effect on the efficiency of wafer transfer and wafer deformation because of contacting with wafer directly. In vacuum environment, wafer transfer robot mainly depends on friction between its end effector and wafer to carry out wafer transfer. When friction transmission end effector is used to pick and transfer wafer, some serious problems will happen easily, such as wafer surface scratch, slope and stick-slip. These problems will decrease efficiency of wafer transfer obviously. In order to improve the efficiency of wafer transfer, it's necessary to detect and prevent from these problems.According to the Major State Basic Research Development Program of China (973 Program)"Principle and realization of transferring large scale and super thin wafer with high-efficiency and stabilization under complex environment", this thesis studied a tactile sensor for measuring three-dimensional (3-D) force and stick-slip on contact surface of wafer transmission. A novel tactile senor was proposed and the principle of measuring 3-D force and stick-slip was discussed. Two prototypes for force measurement and stick-slip detection were designed and developed with their signal processing circuit, respectively. Finally, the experiments for evaluating performances of two prototypes were studied respectively.According to the requirement of transferring large scale wafer (the diameter of more than 300mm) with high-efficiency and stabilization, the typical contact properties between end effector and wafer were discussed, and then the performance indexes which the sensor must meet were determined. Based on features of 3-D force measurement and stick-slip detection, a novel sensor based on the piezo-resistive effect of piezo-resistive conductive ink (PRCI) for measuring 3-D micro-force and the electromagnetic induction of the opposite motion between permanent magnet and chip inductor array for detecting stick-slip was proposed, and its measurement principle was discussed in detail.According to the sensor mechanism and new materials and new technology, the whole architecture of sensor was determined. Then, 3-D force sensor and stick-slip sensor were designed in detail and corresponding prototypes were developed, respectively. Due to piezo-resistive effect of PRCI, a signal processing circuit for micro-force sensor was developed, and due to weak outputs of chip inductor, a signal processing circuit including preamplifier circuit and filter circuit was developed.Finally, an experimental system was established and the experiments for evaluating performances of each prototype were carried out. The results shown that the prototype for micro-force measurement could measure 3-D micro-force and the prototype for stick-slip detection could measure velocity components along X-axis and Y-axis respectively. The results indicated that both of the prototypes can meet the requirements and verified the feasibility of the sensor designed in this thesis.