the sputtering yield

Data from IPP Garching

W. Eckstein, MPIPP Garching, Germany

Book: Sputtering by Particle BombardmentEditors: R. Behrisch, W. Eckstein

• Introduction and Overview (Behrisch, Eckstein)• Computer Simulation of the Sputtering Process

(Eckstein, Urbassek)• Sputtering Yields (Eckstein)• Results of Molecular Dynamics Simulations (Urbassek)• Energy and Angular Distributions of Sputtered Species

(Gnaser)• Chemical Sputtering (Jacob, Roth)• Electronic Sputtering with Swift Heavy Ions (Assmann,

Toulemonde, Trautmann)

• 1. Comparison of experimental and calculated values for the sputtering yield (new book)

• 2. New calculated values and fit formula for the reflection coefficients

Data fitting

• Fitting of calculated yield values for normal incidence of crystalline (amorphous) elemental targets

• values calculated with ACAT (Yamamura)• Values calculated with TRIM.SP (Eckstein)

Advantage of the new fit

• The new fit formula of the sputtering yield at normal incidence allows a better description at low energies near the threshold• The new fit gives more realistic threshold energies

Dependence on the interaction potential

Influence of inelastic energy loss

Calculated energy dependencies

• 376 ion – target combinations• Fitting parameters given in tables

• 266 comparisons with experimental data

• Examples

Calculated energy dependencies of the sputtering yield at normal incidence (1)

Calculated energy dependencies of the sputtering yield at normal incidence (2)

Calculated energy dependencies of the sputtering yield at normal incidence (3)

Calculated angular dependencies

• Fitting of calculated yield values for the angular dependence at a fixed incident energy for elemental targets

• Values calculated with TRIM.SP

• A new fit formula for the angular dependence of the sputtering yield at a fixed energy allows a

better description for low mass ratios and at low energies

Calculated angular dependencies

• 629 calculated angular dependencies• fitting parameters given in tables

• 117 comparisons with experimental data

• examples

Angular dependence of the yield

Calculated angular dependencies of the sputtering yield at specific energies

Main reasons for deviations

Experiment: surface roughness (up to a (factor of 5 for oblique incidence) implantation of gaseous species

(up to 30%) Adsorption of surface impurities• Calculations: interaction potential inelastic energy loss

Multicomponent targets

• Compounds, alloys, isotopic mixtures• Bombardment with nonvolatile species

• Fluence dependent yields• (yield oscillations)

Oscillations in the partial yield

Other yield effects

• Temperature dependence• (yields below threshold, magnetic state)

• Yield fluctuations (ASI distributions)

• Time evolution of the yield