qualification run

Qualification runs process test wafers after PM or process changes to verify tool performance meets specifications before resuming production. Qualification types: (1) Post-PM qual—verify tool returns to baseline after maintenance; (2) New tool qual—extensive characterization before production release; (3) Process change qual—verify changes achieve desired results; (4) Periodic requalification—routine verification on stable tools. Qual wafer set: typically includes monitor wafers (blanket films for rate/uniformity), patterned product wafers (verify pattern-dependent effects), particle wafers (measure adder counts). Specifications verified: process parameters (rate, uniformity, selectivity), metrology results (CD, film properties), defectivity (particle adders, scratches), electrical results (if applicable). Pass criteria: all parameters within control limits, no systematic issues. Fail response: additional troubleshooting, repeat PM, component replacement. Documentation: qual report with all measurements, comparison to baseline, approval signatures. Sign-off: process engineer and equipment engineer approval required. Duration: hours (simple PM) to weeks (new tool qualification). Critical gate preventing out-of-spec production—balance thoroughness with time-to-production pressure.