Patent ID: 7521370

Claim:
A method of operating a plasma reactor chamber with respect to two plasma parameters selected from the group consisting of ion density, wafer voltage, etch rate and wafer current, by controlling chamber parameters of source power and bias power, said method comprising: characterizing the reactor chamber by performing the steps of: a. for each one of said chamber parameters, ramping the level of the one chamber parameter while sampling RF electrical parameters at an RF bias power input to a wafer support pedestal and computing from each sample of said RF electrical parameters the values of said plasma parameters, and storing said values with the corresponding levels of said one chamber parameter as corresponding chamber parameter data; b. for each one of said chamber parameters, deducing, from the corresponding chamber parameter data, a single variable function for each of said plasma parameters having said one chamber parameter as an independent variable; c. constructing combinations of said functions and from said combinations, constructing surfaces defining concurrent values of said chamber parameters, each respective surface corresponding to a respective constant value of one of said plasma parameters, and storing said surfaces; controlling a plasma in the chamber during processing of a production wafer in the chamber in accordance with user-selected values of each of said plasma parameters by performing the following steps: a. for each one of said plasma parameters, fetching a relevant surface of constant value corresponding to the user-selected value of said one plasma parameter, and determining an intersection of the relevant surfaces which defines a target value of source power and bias power; and b. setting said source power and bias power in said chamber, respectively, to the target value.