{
  "schema": "semiagora.process-simulation.v1",
  "experiment_id": "SA-PROC-FEOL-ETCH-PROFILE-001",
  "title": "Etch selectivity and profile",
  "execution_mode": "precomputed-only",
  "model_boundary": "Educational pattern-transfer replay. It is not a plasma model, wet-bench recipe, chamber model, or etch qualification.",
  "process": {
    "family": "subtractive pattern transfer",
    "methods": ["wet isotropic etch", "reactive ion etch", "physical sputter etch"],
    "target_film_thickness_nm": 100,
    "mask_start_thickness_nm": 60,
    "overetch_percent": 20
  },
  "cases": [
    {
      "id": "wet-isotropic-selective",
      "label": "Wet isotropic / high selectivity",
      "vertical_etched_nm": 120,
      "lateral_undercut_nm": 24,
      "cd_loss_nm": 48,
      "mask_loss_nm": 4,
      "mask_remaining_nm": 56,
      "sidewall_angle_deg": 54,
      "selectivity_to_mask": 30,
      "target_cleared": true
    },
    {
      "id": "directional-rie-balanced",
      "label": "Directional RIE / balanced selectivity",
      "vertical_etched_nm": 120,
      "lateral_undercut_nm": 6,
      "cd_loss_nm": 12,
      "mask_loss_nm": 15,
      "mask_remaining_nm": 45,
      "sidewall_angle_deg": 87,
      "selectivity_to_mask": 8,
      "target_cleared": true
    },
    {
      "id": "physical-sputter-low-selectivity",
      "label": "Physical sputter etch / low selectivity",
      "vertical_etched_nm": 120,
      "lateral_undercut_nm": 3,
      "cd_loss_nm": 6,
      "mask_loss_nm": 40,
      "mask_remaining_nm": 20,
      "sidewall_angle_deg": 89,
      "selectivity_to_mask": 3,
      "target_cleared": true
    }
  ],
  "derived_metrics": {
    "balanced_rie_mask_remaining_nm": 45,
    "wet_isotropic_cd_loss_nm": 48,
    "lowest_selectivity_mask_remaining_nm": 20,
    "public_claim": "Etch profile is a tradeoff among clearing the film, preserving the mask, and controlling lateral CD loss."
  },
  "methods": [
    "Use target thickness plus overetch to set the displayed vertical etched depth.",
    "Compute CD loss as two times lateral undercut for symmetric line-space teaching cases.",
    "Compute mask remaining as start mask thickness minus mask loss.",
    "Separate directionality from selectivity so users can compare profile and mask budget independently."
  ],
  "limitations": [
    "No chemistry, pressure, plasma density, ion energy distribution, bias power, endpoint trace, microloading, ARDE, or residue is modeled.",
    "No material-specific etch rate, selectivity calibration, chamber season, or metrology uncertainty is included.",
    "No recipe, tool operation, wafer qualification, or production etch recommendation is implied.",
    "Measured cross-sections, CD-SEM data, endpoint logs, and rights-clean process context are required before calibrated claims."
  ],
  "sources": [
    {
      "label": "MIT OCW 6.152J dry etching lecture",
      "url": "https://ocw.mit.edu/courses/6-152j-micro-nano-processing-technology-fall-2005/59b9f31d836355a3380aa156925508bc_lecture17.pdf",
      "use": "Public lecture material contrasting wet etching, dry etching, anisotropy, selectivity, and reactive ion behavior."
    },
    {
      "label": "MIT OCW 6.774 readings",
      "url": "https://ocw.mit.edu/courses/6-774-physics-of-microfabrication-front-end-processing-fall-2004/pages/readings/",
      "use": "Public reading map that includes etching and process modeling topics."
    }
  ]
}