Patent ID: 7666464

Claim:
A method of performing plasma immersion ion implantation by implanting ions of a selected species into a production workpiece in a reactor chamber, comprising: constructing a lookup table that correlates different values of a predetermined set of process parameters in said reactor chamber with measured values of an ion efficiency factor based upon measurements of plural ion implanted test workpieces, said ion efficiency factor defining a ratio of said selected species ion implanted in each test workpiece of said plural test workpieces to all species ion implanted into said each test workpiece during ion implantation of the selected species; placing said production workpiece on a pedestal in said reactor chamber and feeding into said reactor chamber a process gas comprising said selected species; coupling RF plasma source power to said process gas in said reactor chamber to generate a plasma comprising ions of said selected species so as to perform ion implantation of said ions of said selected species into said production workpiece; coupling RF bias power to said production workpiece from an RF bias power generator through a bias feedpoint of said reactor chamber; measuring RF current at said bias feedpoint to generate a current-related quantity; computing an ion dose-related quantity from said current-related quantity, obtaining a present ion efficiency factor by sensing present values of said set of process parameters and applying said present values of said set of process parameters to said look-up table whereby to obtain from said look-up table said present ion efficiency factor, and multiplying said ion dose-related quantity by said present ion efficiency factor to produce a corrected ion dose-related quantity; and comparing the corrected ion dose-related quantity to a desired ion dose-related quantity to produce a difference, and changing the RF plasma source power as a function of said difference.