Qualification validates that equipment, processes, or materials meet specifications before production use. Types: Equipment qualification: New tool installed and tested before production. Process qualification: New recipe validated with test wafers and electrical results. Material qualification: New chemical, gas, or consumable validated for quality. Stages: IQ (Installation Qualification), OQ (Operational Qualification), PQ (Performance Qualification). IQ: Verify correct installation, utilities, documentation. OQ: Verify operation within specified parameters. PQ: Verify consistent production-worthy results. Wafer runs: Qualification typically requires multiple lots of wafers to demonstrate consistency. Acceptance criteria: Defined specifications for CD, uniformity, defects, electrical parameters. Documentation: Complete records of qualification testing and results. Requalification: Required after maintenance, changes, or extended downtime. SPC: After qualification, ongoing SPC monitoring maintains qualified state. Duration: Days to weeks depending on scope and acceptance criteria.