Automotive MCU (Microcontroller Unit) / Power IC Fab Segment · Capstone Team 4 · Wai, Anand, Vallarino, Mylavarapu
Each major parameter in this simulation is either sourced from published industry standards, benchmarked against public datasets, or transparently calibrated — with the source and rationale documented for every value. The table below shows every parameter, its value, the published range, and the exact source.
| Tool Group | MTBF (Mean Time Between Failures) | MTTR (Mean Time To Repair) | Process Time (hrs/lot) | Defect Rate (per pass) | Drift Rate (per day) |
|---|---|---|---|---|---|
| Lithography | 120 hrs | 8 hrs | 2.5 hrs | 18% | 0.6%/day |
| Etch | 200 hrs | 4 hrs | 1.8 hrs | 13% | 0.4%/day |
| Deposition | 160 hrs | 6 hrs | 3.0 hrs | 11% | 0.5%/day |
| Ion Implant | 180 hrs | 5 hrs | 1.5 hrs | 8% | 0.3%/day |
| CMP | 140 hrs | 6 hrs | 2.0 hrs | 15% | 0.6%/day |
| Metrology | 300 hrs | 3 hrs | 0.8 hrs | 2% | 0.1%/day |
| Published Range | 100–300 hrs | 2–10 hrs | 0.5–4 hrs | 0.5–20% | Model estimate |
| Source | SEMI E10 semi.org/en/Standards/CTR_031244 | Semiconductor manufacturing literature | ITRS/IRDS irds.ieee.org | Team calibration | |
| Assumption | Value We Used | Published Range | Source | Why This Value |
|---|---|---|---|---|
| Base yield (zero defects) | 92% | 85–95% | ITRS/IRDS | Representative upper-midrange baseline for mature automotive-node processes (28–90nm); actual midpoint of the range is 90% |
| Defect impact multiplier | 0.15 per defect | Calibrated | Team calibration | Produces 85–95% yield range matching ITRS benchmarks |
| Rework success rate | 75% | 20–90% | IEEE Trans. Semicon. Mfg. | Moderately optimistic blended average across defect types |
| Die per wafer | 500 | 400–600 | Industry rule of thumb | ~5mm × 5mm die on 200/300mm wafer |
| Lots per month | 210 (7 lots/day × 30 days) | Pilot scope | Project design | 1 product family; 7 lots/day is consistent with 89,752 + 15,248 = 105,000 die ÷ 500 die/lot = 210 lots |
| Chip selling price | $2.50/die | $1–$5 | IC Insights, Gartner, WSTS | Midpoint for automotive MCU ASP |
| Scrap cost per die | $0.80/die | $0.50–$1.50 | IC Knowledge, IBS | Conservative midpoint of manufacturing cost |
| MCUs per vehicle | 8 | 5–20+ | S&P Global Mobility | Conservative average from teardown analyses |
| Line downtime cost | $1–5M/day | $1–5M/day | Automotive News, McKinsey | Widely cited during 2020–2022 chip shortage |
| SECOM dataset | Validation reference | 93.4% pass rate | UCI ML Repository | archive.ics.uci.edu/ml/datasets/SECOM |
These formulas were designed by our team (not copied from a textbook) to capture directional relationships documented in semiconductor yield literature. The constants were determined through calibration: we adjusted values until simulation outputs matched published benchmarks (ITRS 85–95% yield range, SECOM 93.4% pass rate, published defect Pareto rankings).
The simulation uses a seeded pseudorandom number generator (Park & Miller, 1988, Communications of the ACM). Every "random" event (breakdowns, defects, process variation) follows a deterministic sequence controlled by the seed number. Seed 42 always produces the exact same results. When you click "Re-run Simulation," the seed increments (42 → 43 → 44…) and both baseline and scenario are re-run with that same seed, ensuring the only difference between the two runs is the operational lever settings — not the random sequence. The yield improvement is consistent across seeds, confirming the result is not a fluke.
The following corrections were applied in this version relative to the initial prototype:
1. Inspection placement (structural fix): The inline inspection check now runs once per lot (after all tool groups have processed it), not once per tool group. The original code ran the check inside the tool loop, giving a lot up to 6 chances to be inspected per pass — inflating the effective inspection rate from 30% to ~88% at the slider's max position. The corrected implementation matches the intended design: one lot-level inspection check per lot per day.
2. Zero-inspection slider bug: Setting inspection to 0% now correctly disables inspection. The original used p.insp||0.1, which treated 0 as falsy and fell back to 10%. Fixed using p.insp??0.1.
3. Controlled re-run: Clicking Re-run now re-runs both baseline and scenario with the same new seed, ensuring a controlled comparison where only parameters differ.
Note: Due to fix #1, the combined scenario yield improvement in this corrected version will differ from the +5.24 pp figure cited in the project report, which was derived from the earlier prototype. The directional findings remain unchanged.