interlock

Interlocks are safety mechanisms that prevent equipment operation under unsafe conditions, protecting personnel, wafers, and equipment from hazardous situations in semiconductor manufacturing. Interlock types: (1) Hardware interlocks—physical switches, sensors, relays that directly prevent unsafe actions; (2) Software interlocks—control system logic checks before allowing operations; (3) Process interlocks—prevent process execution when prerequisites not met. Safety interlocks: (1) Door interlocks—prevent RF/plasma operation with chamber open; (2) Gas interlocks—verify exhaust flow before allowing toxic gas delivery; (3) Pressure interlocks—prevent chamber opening under vacuum or overpressure; (4) Temperature interlocks—shutdown if temperatures exceed limits; (5) Water flow interlocks—ensure cooling water flows before enabling heat sources; (6) EMO (Emergency Off)—immediate power cutoff for safety. Process interlocks: vacuum level verified before process start, gas flow confirmed before RF ignition, wafer presence confirmed before processing. Interlock hierarchy: safety interlocks cannot be overridden by software; process interlocks may have authorized bypass procedures. Interlock bypass: strictly controlled—requires documentation, authorization, compensating measures, and time-limited validity. Testing: periodic verification that interlocks function correctly (part of PM procedures). Regulatory: SEMI S2 safety guidelines require specific interlocks for semiconductor equipment. Interlock failure: tool goes to safe state (all energy sources off, chambers isolated). Essential safety layer preventing accidents and equipment damage in hazardous fab environment.