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Studies Of Plasma Uniformity And Global Wafer Charging In A High Density, Inductively Coupled Metal Etcher

Introduction Plasma non-uniformity has been identifed as an important potential source of wafer charging in plasma processing equipment. In these studies, typically much higher non-uniformities have been created than would be expected in real manufacturing equipment. This is often done deliberately by introducing nonuniform magnetic fields'32, grids3 or allowing the test wafer to hang off the edge of the chuck4. This paper addresses the question of how much charging would be expected as a result a nonuniformity mechanism for plasmas where the non-uniformity is less than *20%, which is the range of more practical interest for semiconductor manufacturing equipment. Measurements of plasma uniformity were made using a SPORT wafe? , which allows direct measurement of ion current at a number of points at the wafer surface, for a number of different hardware and process conditions. Charging measurements were made using CHARI@77 wafers and a comparison was made between the charging data and the corresponding plasma uniformity data. Finally a numerical simulation was run to calculate the expected charging voltages associated with the observed plasma nonuniformities to compare against the CHARM data.