What does the technology file contain, and why is it necessary?
From PDVerse PnR Interview Handbook, part of the pdVerse Mentor Guide
Short Answer
The technology file is the process "dictionary" — units, layers, vias, placement sites, and routing rules — that gives every coordinate and dimension a consistent, legal meaning. Without it, a netlist can be logically perfect while being physically impossible to build: the router doesn't know what layers exist or how to legally hop between them, and the placer doesn't know a grid compatible with the cells.
Technical Explanation
- The technology file is the process "dictionary" — units, layers, vias, placement sites, and routing rules — that gives every coordinate and dimension a consistent, legal meaning.
- Without it, a netlist can be logically perfect while being physically impossible to build: the router doesn't know what layers exist or how to legally hop between them, and the placer doesn't know a grid compatible with the cells.
- In ICC2, loading a technology file (or referencing a technology library) when you create the design library stores that data inside the library itself — so keeping the original file matters mainly for traceability and future updates, not because the tool re-reads it live.
- Don't assume an edited technology file has automatically changed anything in the database; report what's actually loaded, not what you think you last edited.
- The implementation tech file is not a stand-in for full foundry signoff decks — detailed DRC, LVS, extraction, antenna, and reliability checks need their own qualified inputs.
- Layer definitions by themselves aren't a delay model either — RC technology is a separate, necessary piece of the setup for real interconnect timing.
Visual Verification
The technology file defines physical units, layer pitch, preferred orthogonal routing directions (H/V), and mandatory via metal enclosure rules that prevent manufacturing open circuits.
Command Checks & Actions
set_technology -node 7Applies the node-specific placement, legalization, routing, and extraction settings the technology file encodes. It must run before placement, optimization, or routing, and once set it cannot be changed for that block.
set_technology -report_onlyReports the currently active technology setting without changing it -- the direct way to confirm which technology-file-derived node settings a session is actually running under.
Common Mistake
The Trap: Saying the technology file contains all standard-cell timing arcs, or that passing implementation rules automatically proves signoff DRC cleanliness.
Follow-up Question & Model Response
"Is changing only the layer names enough to move to a different metal stack?"
Candidate Model Response: No; geometry rules, via definitions, RC models, and library compatibility also matter.
Practical Example
Tapeout Scenario: If the netlist's reference cells use one database scale but the design library expects another, physical dimensions may be incompatible even though cell names match. Check the scale, sites, and stack together.
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