carbon footprint

Carbon footprint measures and tracks greenhouse gas (GHG) emissions from fab operations, providing a baseline for reduction efforts and sustainability reporting. Emission scopes (GHG Protocol): (1) Scope 1—direct emissions from owned sources (PFC emissions from etch/CVD, fuel combustion, refrigerant leaks); (2) Scope 2—indirect emissions from purchased electricity and steam; (3) Scope 3—value chain emissions (raw materials, transportation, product use/disposal). Semiconductor-specific sources: PFC process emissions are largest Scope 1 source—CF₄, C₂F₆, SF₆, NF₃, N₂O with high global warming potentials (GWP: CF₄ = 6,500, SF₆ = 23,500). Electricity: fabs consume 30-100 MW, making Scope 2 a major contributor. Calculation methods: IPCC guidelines for PFCs (emission factors × gas usage × 1-utilization × 1-abatement efficiency), electricity × grid emission factor, activity data × emission factors. Reduction strategies: PFC abatement (>90% DRE), process gas substitution (lower GWP alternatives), renewable energy procurement, energy efficiency improvements. Reporting: CDP climate questionnaire, Sustainability Accounting Standards Board (SASB), GRI standards. Targets: Science Based Targets (SBTi) for 1.5°C alignment, absolute and intensity targets (tCO₂e per wafer). Fab benchmark: 5-15 tCO₂e per 300mm wafer equivalent depending on technology node and energy sources. Industry commitments: WSC voluntary PFC reduction targets, corporate net-zero pledges. Critical metric for environmental accountability and increasingly for regulatory compliance.