DFT: The Crucial Gap in Open-Source Chip Design

The Gap That Blocks Tapeout As we neared tapeout, a hard reality set in. Our RTL was verified. Synthesis ran clean through Yosys. Place-and-route was handled by OpenROAD. But none of that gets you a testable chip. The Problem Nobody Talks About Generating a layout is not the same as producing testable silicon. After fabrication, real chips must: Detect manufacturing defects Measure fault coverage Load tester-ready patterns Diagnose failures Without proper DFT infrastructure: Internal state elements are inaccessible Fault coverage cannot be quantified Automated test equipment (ATE) cannot validate the die Yield analysis becomes guesswork You can fabricate a chip. But you cannot confidently prove it works. Why This Gap Is Structural — Not Cosmetic DFT is often misunderstood as “just adding JTAG.” In production silicon, it involves: Structural scan integration Fault modeling and simulation Automatic Test Pattern Generation (ATPG) Coverage measurement Tester-compatible vector export Built-