The Study Of Automatic Electrical Characterization System For Thin Film Transistors

With the wide application of thin film transistor(TFT)displays and other large area electronics,research on TFT device technologies have received more and more attention.To grasp the operation behaviors of TFTs,accurate electrical characterization of the devices is very important.For TFTs,the lowest current level to be measured is normally around the pA level.Moreover,to obtain the full characteristics of the devices,various test conditions need to be carried out.Therefore,a reliable,convenient and low cost electrical characterization system being capable of measuring low current signal down to pA level and suitable for multi-test conditions is urged.The traditional way for characterizing TFTs is based on a probe station with source-meters,but moving probes to make good contacts with all the pads during tests is complicated and of low efficiency.A high quality probe station with low enough leakage current is also expensive and bulky.This thesis optimizes the design of printed circuit boards(PCBs),and implements a circuit board to be able meet the low leakage current measurement requirement of TFTs.Low crosstalk electrically controlled switches are also selected and used for the circuit board.The final automatic characterization system consists of the test fixture,the controller module,PC and source meters.Compared to the conventional probe station based system,this system can be used for characterizing multi-devices with better reliability and efficiency,and is also of much cheaper and compact.The characterization results obtained with this system are verified by those with the probe station.This developed system would provide a low cost,convenient and reliable way for electrical characterization of TFTs.