Selective Epitaxy 

#include <psSelectiveEpitaxy.hpp>

The SelectiveEpitaxy model simulates epitaxial growth that is restricted to specific materials and regions, while other areas remain masked. It supports crystal-orientation–dependent growth rates, allowing for more accurate modeling of faceted epitaxial fronts. The process is “selective” because growth occurs only on materials explicitly marked as epitaxy materials; all other surfaces are treated as masked.

This model is useful for simulating selective area growth (SAG) in semiconductor fabrication, where epitaxy is limited to patterned openings while masked regions remain untouched.

During simulation:

  • The model determines where epitaxy is allowed based on the user-specified material list.
  • Growth rates depend on the surface normal’s orientation, interpolating between {111} and {100} growth rates.
  • Non-epitaxy materials act as masks, preventing growth in those areas.
  • Internally, the model creates a mask layer using Boolean operations on the domain geometry before starting the epitaxial growth.

Constructor Parameters

Parameter Type Description Units / Range Default
materialRates std::vector<std::pair<Material, double>> List of materials where epitaxy is allowed, with corresponding rate scaling factors. Scaling factor (unitless) —
rate111 double Growth rate for {111} crystal orientations. User units (e.g., µm/s) 0.5
rate100 double Growth rate for {100} crystal orientations. User units (e.g., µm/s) 1.0

Example Usage

Basic usage – Epitaxy on Si only, with default {111} and {100} rates:

C++

 
using namespace viennaps;

std::vector<std::pair<Material, double>> epiMaterials = {
    {Material::Si, 1.0}
};

auto epi = SmartPointer<SelectiveEpitaxy<double, 3>>::New(epiMaterials);

Python

 
import viennaps as vps

epiMaterials = [
    (vps.Material.Si, 1.0)
]

model = vps.SelectiveEpitaxy(
    materialRates=epiMaterials
)

Custom orientation rates – Faster {100} growth, slower {111} growth:

C++

 
using namespace viennaps;

std::vector<std::pair<Material, double>> epiMaterials = {
    {Material::Si, 1.0}
};

double r111 = 0.3; // µm/s
double r100 = 1.2; // µm/s

auto epi = SmartPointer<SelectiveEpitaxy<double, 3>>::New(epiMaterials, r111, r100);

Python

 
import viennaps as vps

epiMaterials = [
    (vps.Material.Si, 1.0)
]
model = vps.SelectiveEpitaxy(
    materialRates=epiMaterials,
    rate111=0.3,  # µm/s
    rate100=1.2   # µm/s
)

Tips:

  • The topmost material in the domain must be an epitaxy material; otherwise, an error is logged.
  • At least two level sets are required in the domain for selective epitaxy.
  • Mask layers are automatically generated during initialization to block growth in non-epitaxy regions.