{
  "schema": "semiagora.process-simulation.v1",
  "experiment_id": "SA-PROC-METRO-CDSEM-OVERLAY-001",
  "title": "CD-SEM and overlay control replay",
  "execution_mode": "precomputed-only",
  "model_boundary": "Educational dimensional-metrology replay. It connects CD maps and overlay vectors to control language; it is not a calibrated CD-SEM, overlay-tool, or process-control report.",
  "lesson_route": "/learn/process-metrology",
  "simulation_route": "/simulations/process-cd-sem-overlay-control",
  "measurement_context": {
    "nominal_cd_nm": 100,
    "cd_sites": "3 x 3 teaching sample",
    "overlay_units": "nm",
    "method": "critical-dimension and registration replay"
  },
  "cd_nm_matrix": [
    [101.5, 100.5, 101.0],
    [100.5, 99.5, 100.0],
    [101.0, 100.0, 101.5]
  ],
  "overlay_vectors_nm": [
    { "site": "SW", "dx": -1.2, "dy": 0.8, "magnitude": 1.44 },
    { "site": "S", "dx": 0.6, "dy": 1.4, "magnitude": 1.52 },
    { "site": "SE", "dx": 1.9, "dy": 1.0, "magnitude": 2.15 },
    { "site": "W", "dx": -1.6, "dy": -0.7, "magnitude": 1.75 },
    { "site": "C", "dx": 0.1, "dy": 0.2, "magnitude": 0.22 },
    { "site": "E", "dx": 2.4, "dy": -1.5, "magnitude": 2.83 },
    { "site": "NW", "dx": -2.0, "dy": 1.8, "magnitude": 2.69 },
    { "site": "N", "dx": 1.1, "dy": -2.2, "magnitude": 2.46 },
    { "site": "NE", "dx": 2.7, "dy": 1.8, "magnitude": 3.24 }
  ],
  "derived_metrics": {
    "cd_mean_nm": 100.61,
    "cd_range_nm": 2.0,
    "cd_3sigma_nm": 1.97,
    "overlay_p95_nm": 3.08,
    "overlay_worst_nm": 3.24
  },
  "methods": [
    "Compute CD mean, range, and 3-sigma from saved site samples.",
    "Compute overlay vector magnitude from dx and dy registration errors.",
    "Report p95 and worst-site overlay so nominal alignment is not overtrusted.",
    "Keep CD and overlay separate because linewidth control and layer registration fail differently."
  ],
  "limitations": [
    "No SEM image processing, line-edge roughness, focus/exposure context, sampling-plan optimization, tool matching, or uncertainty budget is included.",
    "No qualified metrology, process-control release, scanner correction, facility procedure, or production overlay claim is implied.",
    "Real dimensional-metrology evidence requires calibrated tools, raw images or summary files, sampling plans, gauge studies, and rights-clean data.",
    "This replay is not a CD-SEM recipe, overlay correction deck, or wafer disposition rule."
  ],
  "sources": [
    {
      "label": "NIST dimensional metrology for nanoscale patterns",
      "url": "https://www.nist.gov/programs-projects/dimensional-metrology-nanoscale-patterns",
      "note": "Public NIST page describing nanoscale pattern dimensions, critical-dimension control, and metrology needs."
    }
  ]
}