Beam Drift Phenomenon in Electron Beam Lithography through Backscattered Electron Detection

Multiple Electron beam lithography is one of the promising technologies for 22nm-node Integrated Circuit (IC) fabrications. For the purpose of improving system throughput, large amount of beams should be driven at the same time, and miniature electrostatic elements are widely utilized in these systems. Silicon Photodiodes Detector (SPD) can be used in the systems under the small working distance and low electron energy. The advantages of small profile, high electron collection efficiency and efficient cost make it suitable to integrate in the multiple electron beam lithography system.he purpose of this research is to build the silicon photodiodes detector in the Scanning Electron Microscope (SEM) system. The detection performance is illustrated under the low electron energy and small working distance through experiment. The quadrant cells of active area on silicon photodiodes are used to analysis the backscattered electron generated from the primary beam. The beam drifting problem of the electron beam optical system for the long time operation is observed. The characteristic of backscattered electron in of Gaussian distribution is simulated on quadrant cell of SPD. The variations of quadrant cell signal in experiment can be analysis through the simulation. Besides, Backscattered Electron Image (BEI) is built through deflection coil scanning and makes it possible to forming an image in the developing massively parallel mask-less lithography system (MPML2).