feat: add HF cryogenic plasma etching model for SiO2

examples/HFCryo4Cases/CMakeLists.txt

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+project(HFCryo4Cases LANGUAGES CXX)
+
+viennaps_add_example(${PROJECT_NAME} "${PROJECT_NAME}.cpp")

examples/HFCryo4Cases/HFCryo4Cases.cpp

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+#include <algorithm>
+#include <cmath>
+#include <iomanip>
+#include <iostream>
+#include <string>
+#include <vector>
+
+#include <geometries/psMakeTrench.hpp>
+#include <models/psHFCryoEtching.hpp>
+#include <process/psProcess.hpp>
+#include <psUtil.hpp>
+
+#include <lsToMultiSurfaceMesh.hpp>
+#include <lsVTKWriter.hpp>
+
+using namespace viennaps;
+
+static constexpr double gridDelta = 1.0;
+static constexpr double xExtent = 80.0;
+static constexpr double yExtent = 2000.0;
+static constexpr double trenchWidth = 10.0;
+static constexpr double maskHeight = 80.0;
+static constexpr double processTime = 400.0;
+
+// Writes the surface mesh and returns the etch depth: how far the deepest
+// point of the etch front sits below the original substrate surface (y = 0).
+static double saveMeshAndDepth(SmartPointer<Domain<double, 2>> domain,
+                               const std::string &filename, double T) {
+  auto mesh = viennals::Mesh<double>::New();
+  viennals::ToMultiSurfaceMesh<double, 2>(domain->getLevelSets(), mesh).apply();
+
+  const size_t n = mesh->nodes.size();
+  mesh->getPointData().insertNextScalarData(std::vector<double>(n, T),
+                                            "Temperature_K");
+  viennals::VTKWriter<double>(mesh, filename).apply();
+
+  double minY = 0.0;
+  for (size_t i = 0; i < n; ++i)
+    minY = std::min(minY, mesh->nodes[i][1]);
+  return -minY;
+}
+
+static double runCase(double T, bool useDiffusion) {
+  auto domain =
+      SmartPointer<Domain<double, 2>>::New(gridDelta, xExtent, yExtent);
+  MakeTrench<double, 2>(domain, trenchWidth, 0.0, 0.0, maskHeight, 0.0, false,
+                        Material::SiO2)
+      .apply();
+
+  HFCryoParameters<double> params;
+  params.temperature = T;
+  params.ionFlux = 3.0;
+  params.etchantFlux = 5.0e3;
+  params.gamma_HF = 0.9;
+  params.Desorption.nu0 = 1.0e8;
+  params.Desorption.E_des = 0.20;
+  params.Reaction.A_r = 3.0e2;
+  params.Reaction.E_a = 0.10;
+  params.DirectReaction.A_r = 1.0e4;
+  params.DirectReaction.E_a = 0.25;
+  params.IonActivation.A_act = 1.0;
+  params.Diffusion.D0 = 1.0e3;
+  params.Diffusion.omega = 0.25;
+  params.Ions.meanEnergy = 150.0;
+  params.Ions.sigmaEnergy = 10.0;
+  params.Ions.exponent = 600.0;
+  params.Config.useTemperatureDependence = true;
+  params.Config.usePhysisorption = true;
+  params.Config.useSurfaceDiffusion = useDiffusion; // toggled per run
+  params.Config.T_ref = 300.0;
+
+  auto model = SmartPointer<HFCryoEtching<double, 2>>::New(params);
+  Process<double, 2> process(domain, model, processTime);
+
+  RayTracingParameters rayParams;
+  rayParams.raysPerPoint = 5000;
+  process.setParameters(rayParams);
+
+  AdvectionParameters advParams;
+  advParams.spatialScheme = SpatialScheme::WENO_3RD_ORDER;
+  advParams.temporalScheme = TemporalScheme::RUNGE_KUTTA_2ND_ORDER;
+  process.setParameters(advParams);
+
+  process.apply();
+
+  const std::string tag = useDiffusion ? "diffON" : "diffOFF";
+  const std::string fname =
+      "HFCryo_" + tag + "_T" + std::to_string((int)T) + "K.vtp";
+  return saveMeshAndDepth(domain, fname, T);
+}
+
+int main() {
+  Logger::setLogLevel(LogLevel::WARNING);
+  omp_set_num_threads(4);
+
+  units::Length::setUnit(units::Length::NANOMETER);
+  units::Time::setUnit(units::Time::SECOND);
+
+  const double Tlist[4] = {150., 200., 250., 300.};
+
+  std::cout << "=== HF Cryo Etching: surface diffusion OFF vs ON ===\n";
+  std::cout << "Geometry: " << trenchWidth << "nm trench, " << maskHeight
+            << "nm mask, " << processTime << "s process\n\n";
+
+  double depthOff[4], depthOn[4];
+
+  std::cout << "--- Surface diffusion OFF ---\n";
+  for (int i = 0; i < 4; ++i) {
+    std::cout << "  T=" << std::setw(3) << (int)Tlist[i] << "K ... "
+              << std::flush;
+    depthOff[i] = runCase(Tlist[i], false);
+    std::cout << "depth = " << std::fixed << std::setprecision(1) << depthOff[i]
+              << " nm\n";
+  }
+
+  std::cout << "\n--- Surface diffusion ON ---\n";
+  for (int i = 0; i < 4; ++i) {
+    std::cout << "  T=" << std::setw(3) << (int)Tlist[i] << "K ... "
+              << std::flush;
+    depthOn[i] = runCase(Tlist[i], true);
+    std::cout << "depth = " << std::fixed << std::setprecision(1) << depthOn[i]
+              << " nm\n";
+  }
+
+  std::cout << "\n=== Summary: trench etch depth (nm) ===\n";
+  std::cout << "   T[K]    diffOFF     diffON      gain\n";
+  for (int i = 0; i < 4; ++i) {
+    const double gain =
+        depthOff[i] > 1e-9 ? (depthOn[i] / depthOff[i] - 1.0) * 100.0 : 0.0;
+    std::cout << "   " << std::setw(4) << (int)Tlist[i] << "   " << std::setw(8)
+              << std::setprecision(1) << depthOff[i] << "   " << std::setw(8)
+              << depthOn[i] << "   " << std::setw(7) << std::setprecision(1)
+              << gain << "%\n";
+  }
+
+  std::cout << "\n=== Done: 8 VTP files (HFCryo_diffOFF/ON_T*.vtp) ===\n";
+  return 0;
+}

examples/HFCryoEtching/CMakeLists.txt

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+project(HFCryoEtching LANGUAGES CXX)
+
+viennaps_add_example(${PROJECT_NAME} "${PROJECT_NAME}.cpp")

examples/HFCryoEtching/HFCryoEtching.cpp

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+#include <cmath>
+#include <iostream>
+#include <string>
+
+#include <geometries/psMakeTrench.hpp>
+#include <models/psHFCryoEtching.hpp>
+#include <process/psProcess.hpp>
+#include <psUtil.hpp>
+
+using namespace viennaps;
+
+static void runCase(const std::string &label, double T, double gridDelta,
+                    double xExtent, double yExtent, double trenchWidth,
+                    double maskHeight, double processTime,
+                    HFCryoParameters<double> params) {
+  params.temperature = T;
+
+  auto domain =
+      SmartPointer<Domain<double, 2>>::New(gridDelta, xExtent, yExtent);
+  MakeTrench<double, 2>(domain, trenchWidth, 0.0, 0.0, maskHeight, 0.0, false,
+                        Material::SiO2)
+      .apply();
+
+  auto model = SmartPointer<HFCryoEtching<double, 2>>::New(params);
+  Process<double, 2> process(domain, model, processTime);
+
+  RayTracingParameters rayParams;
+  rayParams.raysPerPoint = 3000;
+  process.setParameters(rayParams);
+
+  AdvectionParameters advParams;
+  advParams.spatialScheme = SpatialScheme::WENO_3RD_ORDER;
+  advParams.temporalScheme = TemporalScheme::RUNGE_KUTTA_2ND_ORDER;
+  process.setParameters(advParams);
+
+  process.apply();
+
+  std::string tag = label + "_T" + std::to_string((int)T) + "K";
+  domain->saveSurfaceMesh(tag + ".vtp", true);
+  domain->saveHullMesh(tag + "_hull.vtp");
+  std::cout << "done -> " << tag << ".vtp\n";
+}
+
+int main() {
+  Logger::setLogLevel(LogLevel::WARNING);
+  omp_set_num_threads(4);
+
+  units::Length::setUnit(units::Length::NANOMETER);
+  units::Time::setUnit(units::Time::SECOND);
+
+  const double gridDelta = 1.0;
+  const double xExtent = 80.0;
+  const double yExtent = 700.0;
+  const double trenchWidth = 10.0;
+  const double maskHeight = 50.0;
+  const double processTime = 90.0;
+
+  // Base parameters shared by both cases
+  HFCryoParameters<double> params;
+  params.ionFlux = 1.0;
+  params.etchantFlux = 1.0e3;
+  params.gamma_HF = 0.9;
+  params.Desorption.nu0 = 1.0e8;
+  params.Desorption.E_des = 0.20;
+  params.Reaction.A_r = 3.0e2;
+  params.Reaction.E_a = 0.10;
+  params.IonActivation.A_act = 1.0;
+  params.Ions.meanEnergy = 100.0;
+  params.Ions.sigmaEnergy = 10.0;
+  params.Ions.exponent = 300.0;
+
+  // Print D_s per temperature
+  std::cout << "=== HF Cryo Etching | Surface Diffusion Comparison ===\n\n";
+  std::cout << "T(K)   k_des      k_r      k_r_direct   D_s(D0=1e3)\n";
+  std::cout << "------------------------------------------------------\n";
+  double Tlist[4] = {150.0, 200.0, 250.0, 300.0};
+  for (int i = 0; i < 4; ++i) {
+    params.temperature = Tlist[i];
+    params.Diffusion.D0 = 1.0e3;
+    params.Diffusion.omega = 0.25;
+    std::cout << Tlist[i] << "K  " << params.k_des() << "  " << params.k_r()
+              << "  " << params.k_r_direct() << "  " << params.D_s() << "\n";
+  }
+  std::cout << "\n";
+
+  // Save initial geometry
+  {
+    auto domain =
+        SmartPointer<Domain<double, 2>>::New(gridDelta, xExtent, yExtent);
+    MakeTrench<double, 2>(domain, trenchWidth, 0.0, 0.0, maskHeight, 0.0, false,
+                          Material::SiO2)
+        .apply();
+    domain->saveSurfaceMesh("HFCryo_initial.vtp", true);
+    std::cout << "Initial geometry saved.\n\n";
+  }
+
+  // ── Case A: No surface diffusion (D0=0) ──────────────────────────────────
+  std::cout << "=== Case A: No Surface Diffusion (D0=0) ===\n";
+  params.Diffusion.D0 = 0.0;
+  params.Diffusion.omega = 0.25;
+  for (int i = 0; i < 4; ++i) {
+    std::cout << "  T=" << Tlist[i] << "K ... ";
+    std::cout.flush();
+    runCase("NoDiff", Tlist[i], gridDelta, xExtent, yExtent, trenchWidth,
+            maskHeight, processTime, params);
+  }
+
+  // ── Case B: With surface diffusion (D0=1e3) ───────────────────────────────
+  std::cout << "\n=== Case B: With Surface Diffusion (D0=1e3) ===\n";
+  params.Diffusion.D0 = 1.0e3;
+  params.Diffusion.omega = 0.25;
+  for (int i = 0; i < 4; ++i) {
+    std::cout << "  T=" << Tlist[i] << "K ... ";
+    std::cout.flush();
+    runCase("Diff", Tlist[i], gridDelta, xExtent, yExtent, trenchWidth,
+            maskHeight, processTime, params);
+  }
+
+  std::cout << "\n=== Done ===\n";
+  std::cout << "Compare in ParaView:\n";
+  std::cout << "  NoDiff_T150K.vtp  vs  Diff_T150K.vtp\n";
+  std::cout << "  NoDiff_T200K.vtp  vs  Diff_T200K.vtp\n";
+  std::cout << "Color by MaterialIds to see Mask / SiO2\n";
+
+  return 0;
+}