Patent ID: 6972524

Claim:
A method of approximating an ion energy distribution function (IEDF) at a substrate surface of a substrate, said substrate being processed in a plasma processing chamber, comprising: providing a first voltage value, said first voltage value representing a value of a first voltage that represents a DC potential (V DC ) at said substrate surface; providing a peak low frequency RF voltage value (V LFRF(PEAK) ) during plasma processing, said peak low frequency RF voltage (V LFRF(PEAK) ) value representing a peak value of a low frequency RF voltage (V LFRF ) supplied to said plasma processing chamber; providing a computing device configured to compute said IEDF from said first voltage value and said peak low frequency RF voltage value (V LFRF(PEAK) ) in accordance with f ⁡ ( E ) ≡ ( ⅆ V LF ⅆ t ) - 1 wherein V LF ⁡ ( t ) = [ ( V LFRF ⁡ ( PEAK ) - V dc 2 ) 1 / 2 - ( V LFRF ⁡ ( PEAK ) - V dc 8 ) 1 / 2 ⁢ sin ⁢ ⁢ ω ⁢ ⁢ t ] 2 .