# Gt3 Backside Route Policy

> Apply and validate GT3 backside routing policy in Innovus. Use when configuring CTS/PDN/signal layer usage, submitting GT3 consistency runs, diagnosing zero-backside-nets, or enforcing BPR-reserved-for-PDN constraints.

- Skill: `mr-fang-vlsi/gt3-backside-route-policy` (Agent Skill, multi-file: 5 files)
- Install (CLI): `npx skillmds@latest add mr-fang-vlsi/gt3-backside-route-policy`
- Raw SKILL.md: https://api.skillmd.com/api/skills/mr-fang-vlsi/gt3-backside-route-policy/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: Mr-Fang-VLSI (https://skillmd.com/u/mr-fang-vlsi)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/mr-fang-vlsi/gt3-backside-route-policy

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# GT3 Backside Route Policy

Apply this policy for GT3 experiments unless the task brief explicitly overrides it.

## Policy defaults
1. Keep CTS route on `M4/M5`.
2. Keep PDN on high layers (`BSPDN_HI` => `M6/M7`).
3. Reserve `BPR` for PDN.
4. Allow backside signal routing on `BM2/BM1` only (`index 1..2`).
5. Treat `BM2 -> BM1 -> M0 -> M1` as the current working signal-entry hypothesis until disproved by a topology-validity gate.
6. Do not assume direct `BM1 -> M1` connectivity without explicit tool or techlef evidence.

## Submit controlled run

```bash
ROOT=/mnt/research/Hu_Jiang/Students/Fang_Donghao/TAMU-ASAP07-BSPDN-BPR-V0.00
cd "$ROOT"

TASK_BRIEF=<task_brief_md> \
BACKSIDE_SIGNAL_NET_FILE=<net_list_txt> \
BACKSIDE_SIGNAL_NET_BOTTOM_INDEX=1 \
BACKSIDE_SIGNAL_NET_TOP_INDEX=2 \
bash scripts/debug/submit_gt3_route_rc_consistency.sh <design> <run_tag>
```

Monitor outputs:
- `slurm_logs/04_delay_modeling/<run_tag>.monitor.md`
- `slurm_logs/04_delay_modeling/<run_tag>.monitor.history.tsv`

## Post-run checks
1. Verify backside signal occupancy appears on BM layers.
2. Verify signal occupancy does not use BPR.
3. Verify CTS remains on `M4/M5` window.
4. Verify the run does not rely on an unproven shortcut such as direct `BM1-M1`.

Load `references/policy_checks.md` for quick command snippets.