Detection Principle Of Stick-slip State On Wafer Transmission Surface And Its Sensor Design

Wafer transfer robot is the core equipment in Integrated Circuit(IC) Industry,whose stability and rapidity have a great influence on efficiency of IC industry.When end effector accelerates or decelerates, due to friction insufficiency, thestick-slip phenomenon will occur on the contact surface, which not only affectsstability of transferring system, the generated debris also decreases the cleanlinessof working environment and brings a negative influence on follow-up process. Inorder to reduce adverse affects caused by stick-slip process and meanwhile, improvetransferring efficiency, the stick-slip state between wafer and end effector can beacquired by sensors and this information can be used as feedback to control the endeffector.Based on scheme above, according to the national973project ‘Principle andrealization of transferring large scale and super thin wafer with high efficiency andstabilization under complex environment’(granted No.2009CB724206), a noveltactile sensor that has stick-slip detecting function applied in wafer transferenvironment is developed in this paper. After lucubrating its sensing principle,sensor prototype is designed and made, some experiments are carried out to test itsperformances.First, typical model of wafer transfer system is constructed, frictioncharacteristics in time domain and frequency domain are analyzed under ‘stick’,‘slip’, and ‘stick-slip alternation’ status, and stick-slip state judging method oncombination of friction low frequency component and high frequency component isproposed.Second, based on piezoresistive effect and electromagnetic principle, astick-slip detecting method is raised. By constructing piezoresistive conductive ink,detection of low frequency component in friction is realized and by magnet-coilsensor, detection of high frequency is realized.Considering the sensing principle and using requirements, in order to increasebandwidth and resolution of stick-slip state detection sensor, the structureoptimization design is carried out. Aiming at achieve conditioning and differentialfunction, sensor signal processing circuit is devised. After design and simulation,sensor prototype is manufactured for experiment research.Finally, indicator testing experiment of piezoresistive conductive ink sensor,model identification experiment of magnet-coil sensor and wafer transferexperiment are built to assess the performance of designed sensor. Through theseexperiment results, the bandwidth, resolution and error are obtained. Therefore, itproves that the excogitated sensor has the capacity of detecting current state on contact surface.