Ion Beam Etching (IBE) Process 

#include <psIonBeamEtching.hpp>

The IonBeamEtching model simulates anisotropic material removal by a directed ion beam, optionally including redeposition of sputtered material. It uses a physics-based yield function to compute the local etch rate as a function of incidence angle and ion energy, making it suitable for realistic simulation of focused or broad-beam ion etching setups.

The process can be configured with:

  • Mask materials – specified as a list of Material types that are excluded from etching.
  • IBE parameters – a complete set of physical and process-specific properties, such as ion energy distribution, sputter yield function, incidence angles, redeposition thresholds, and material-specific etch rates.

During simulation:

  • Ion trajectories are traced using ViennaPS’ ray-tracing engine.
  • The surface model calculates local etch velocities from the simulated ion flux, redeposition flux, and yield function.
  • Particle–surface interactions determine whether an ion sputters material, is reflected, or causes redeposition, with reflection modeled via a coned-cosine distribution.

By adjusting the IBEParameters and mask configuration, the model can replicate a wide range of IBE scenarios—from purely directional sputtering to processes with significant redeposition effects.

Parameter Type Description Units / Range Default
planeWaferRate double Base etch rate for a reference (plane) wafer surface. User-defined (e.g., nm/min) 1.0
materialPlaneWaferRate map Material-specific plane wafer rates overriding planeWaferRate. User-defined per Material —
meanEnergy double Mean ion energy in the beam. eV 250
sigmaEnergy double Standard deviation of the ion energy distribution. eV 10
thresholdEnergy double Minimum ion energy required for sputtering. eV 20
exponent double Exponent controlling the angular distribution of the ion source. > 1 100
n_l double Shape parameter for the reflection energy distribution. > 1 10
inflectAngle double Inflection angle for energy reflection behavior. degrees 89
minAngle double Minimum angle for coned reflection. degrees 85
tiltAngle double Tilt angle of the incoming ion beam relative to surface normal. degrees 0
yieldFunction function User-defined sputter yield as a function of incidence angle θ (in radians). — 1.0
redepositionThreshold double Minimum sputtered particle energy or yield before redeposition is considered. User-defined 0.1
redepositionRate double Fraction of sputtered material redeposited on the surface. 0.0 – 1.0 0.0