Research On Micro-fiber Array Contact Surface And Stick-slip Sensor For Friction-type Wafer Transmission

Integrated Circuit(IC)industry is a foundational,precursory and strategic core industry of the national economy and social development.The fabircation of ICs require wafers to be transferred frequently among hundreds of processes,and thereby the capacity of wafer transfer has a crucial role in the development of IC industry.As one key IC manufacturing equipment,wafer transfer robots take a task of positioning wafers accurately and transferring them fast and steadily.With the development of IC fabrication toward large-size wafers and small feature size,the production line becomes more and more compact with higher precision & speed in the more cleaner enviroment,which brings a higher requirement for the performance of wafer transfer robot.Wafer-transmission contact surface with high-friction horizontally and low-adhesion vertically and avoiding wafer stick-slip is crucial in transferring large-size wafers with high-efficiency and stabilization for friction-type wafer transmission.Supported by the National Program on Key Basic Research Project(973 Program),this dissertation focused on the research on micro-fiber array contact surface and stick-slip tactile sensor for friction-type wafer transmission.This dissertation proposes a design method of micro-fiber-array contact surface with high-friction and low-adhesion for friction-type wafer transmission,flexible contact models with Lu Gre model for wafer flexible support validated by experiment study,and a stick-slip sensor detecting stick-slip on the flexible contact surface based on electromagnetic induction for friction-type wafer transmission.Besides,a prototype of micro-fiber-array contact surface and a prototype of stick-slip sensor have been made and their validation experiments have also been conducted.In the aspect of the research on micro-fiber-array contact surface for friction-type wafer transmission,this dissertation focuses on the requirement of picking large-size wafer high-efficiency and steadily,builds a friction model and an adhesion model based on the micro-fiber array contact surface for friction-type wafer transmission.Then,four functional failures of micro-fiber array are analyzed as well as their causes,and those constraints about the structure of micro-fiber array with high-friction and low-adhesion are obtained.Next,a design method of micro-fiber-array for friction-type wafer transmission is also proposed in details,and then a prototype based on SU-8 is designed and prepared.In the aspect of the research on flexible dynamic contact modelling and its experimental study,this dissertation makes the contact between a flexible bump and a wafer be equivalent to that between an elastomer and a rigid body,proposes a flexible dynamic contact model combining with LuGre model and beam-spring network model,which is able to accurately describe dynamic characteristics of friction on a flexible contact surface and contact-lattice displacement with time evolution,and defines a dimensionless parameter ? which is capable of simplifying the above model as a flexible dynamic contact model combining with Lu Gre model and single-beam model.Then,a simulation algorithm based on the above model is designed.The experimental and simulation results validate the feasibility of the above flexible dynamic contact model as well as the effectiveness of its simulation algorithm,as a research basis of the design of stick-slip sensor for friction-type wafer transmission following chapter.In the aspect of the research on the contact-surface stick-slip sensor for friction-type wafer transmission,this dissertation focuses on the requirement of detecting contact information on the wafer transfer surface,proposes a novel stick-slip sensor for flexible contact surface based on electromagn etic induction.Then,a prototype of stick-slip sensor with a compact structure is designed and made for the application of wafer transfer,and its signal conditioning is also conducted.Next,a specific end effector is designed for mounting and testing the sensor.Finally,those experimental systems are built for testing the prototype with micro-fiber array and the prototype of stick-sip sensor,respectively,and then corresponding experiments are conducted.The results show that the prototype of micro-fiber array based on SU-8 is with high-friction horizontally and low-adhesion vertically,and compared with the common one,it is capable of improving the maximum acceleration of wafer transfer(increased by 47%),which validates the feasibility of the design method of micro-fiber array for friction-type wafer transmission.The results also indicate that the stick-slip sensor is able to detect stick-slip states on the flexible contact surface directly by comparing its output with a threshold,identify the abrupt change direction of friction force,detect stick-slip states of the wafer in the whole process from stick to slip,and capable of online detecting stick-slip states of the wafer on the wafer transfer robot,which validates the feasibility of the stick-slip sensor.This stick-slip sensor provides a necessary contact information feedback to realize anti-control of the wafer transfer robot,and an important approach for evaluating and improving the quality of trajectory planning and the motion performance of the robot.