The wafer charge-up effect (antenna effect) in a magnetically enhanced reactive ion etching system is examined carefully. A three-stage antenna effect is observed. The antenna effect begins to occur from around the end-point of main-etch step to the early stage of over-etch step. During the elongated over-etch period, recovery phenomenon is observed for the first time. It is found that the charging of photo-resist disturbs the local electrical field. The plasma uniformity is degraded by the interaction of magnetic field and the local electrical field. The magnitude and polarity of charging current depend on both test pattern layout and wafer layout. Therefore, to predict the antenna effect on a complex product circuit by only monitoring simple test patterns need careful analysis and correlation.