RECOVERY PHENOMENON AND LOCAL-FIELD SENSITIVITY ON WAFER CHARGE-UP EFFECT OF MAGNETICALLY ENHANCED REACTIVE ION ETCH SYSTEM

The wafer charge-up effect (antenna effect) in a magnetically enhanced reactive ion etching system is examined carefully. A three-stage ante nna 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 observe d for the first time. It is found that the charging of photo-resist di sturbs the local electrical field. The plasma uniformity is degraded b y the interaction of magnetic field and the local electrical field. Th e magnitude and polarity of charging current depend on both test patte rn layout and wafer layout. Therefore, to predict the antenna effect a n a complex product circuit by only monitoring simple test patterns ne ed careful analysis and correlation.