bulk gas system

Bulk gas systems provide central storage and distribution of high-purity process gases used throughout the semiconductor fab. **Common gases**: Nitrogen (N2 - largest volume), oxygen, argon, hydrogen, helium, ammonia, silane, phosphine, arsine, and many specialty gases. **Storage**: Bulk liquid storage tanks (N2, O2, Ar, He) vaporized on demand. Tube trailer or cylinder storage for others. **Purity grades**: Electronic grade, ultra-high purity (UHP), semiconductor grade - ppb impurity levels. **Distribution**: Electropolished stainless steel piping, welded connections, point-of-use purifiers, mass flow controllers at tools. **Pressure regulation**: Step-down from tank pressure through multiple regulation stages to tool delivery pressure. **Safety systems**: Gas detection throughout fab, automatic shutoffs, ventilated gas cabinets for toxic gases, seismic bracing. **Categories**: Inert (N2, Ar), oxidizers (O2), flammables (H2, silane), toxics (PH3, AsH3), corrosives (Cl2, HCl). Each has specific handling requirements. **Redundancy**: Critical gases have backup supplies and N+1 delivery capability.