ION ENERGY DETERMINATION FOR RF PLASMA AND ION-BEAM USING A MULTIGRIDRETARDING-FIELD ANALYZER

The ion energy distribution of a capacitively coupled r.f. (13.56 MHz) plasma and ion beam source has been measured. The extraction optics c onsists of two stainless steel grids. The source has been operated in two different configurations, either with or without extraction optics . In the latter case the discharge serves only as a plasma source to b e used directly or as remote plasma. For measurements of ion energy in the plasma mode a four-grid retarding field analyser (RFA) was used. For analysis of ion energy in the ion beam mode a slightly different R FA was used, because the retarding voltage here is higher, correspondi ng to extraction voltages of several hundred volts. In the plasma mode , all distributions exhibit a single-peak structure with a low-energy tail. With increasing pressure from 4 x 10(-2) to 4 Pa the distributio n width shows an increase from 1.5 to 4.5 eV, whereas the average ion energy decreases from 48 to 17.4 eV. In the ion beam mode, the ion ene rgy distribution is studied as a function of the r.f. power and pressu re.