Effects of surface charging on the notching in poly-silicon etch

Summary form only given, as follows. Various pattern distortions due to the pattern charging have been reported. In the poly-silicon etching for the line and space patterning, a notching phenomenon occurs in the outer-most line. It is proposed that the different angular velocity distributions of electrons and ions due to the sheath are the substantial reason for the notching. In our works, we performed a particle simulation to study the effects of the surface charging on the poly-Si notching. Trajectories of electrons and ions were calculated in the pattern-scale calculation domain. The electric field configuration derived from the charge distribution on the pattern surface was included in the trajectory calculation. By counting the number of electrons and ions arriving at each surface position, the charge distribution was revised. The self-consistent simulation with including these three steps, the derivation of the charge distribution, electric field calculation and trajectory tracing was performed. From the works, we noticed that the local electric field near the bottom surface causes the ion trajectory to vent abruptly and to impact the lower surface of the outer-most line pattern which has little positive charge due to the electron irradiation. But for the inner line pattern, the electric field from the charging of the surface inhibits the ion's impact. The charge redistribution in the poly line surface due to the bottom charge increases the notching effects.