An oxidation furnace is a specialized diffusion furnace designed to grow thermal silicon dioxide by exposing silicon wafers to an oxidizing ambient at high temperature. Process: Si + O2 -> SiO2 (dry) or Si + 2H2O -> SiO2 + 2H2 (wet/steam). Silicon is consumed as oxide grows. Dry oxidation: Pure O2 ambient. Slow growth rate but highest quality oxide. Used for gate oxides and thin critical oxides. Wet oxidation: Steam (H2O) ambient. Much faster growth rate (5-10x dry). Used for thick field oxides, isolation, and pad oxides. Temperature: 800-1200 C. Higher temperature = faster oxidation rate. Deal-Grove model: Mathematical model predicting oxide thickness vs time. Linear regime (thin oxide, surface-reaction limited) and parabolic regime (thick oxide, diffusion limited). Furnace design: Horizontal or vertical quartz tube with controlled gas delivery. Pyrogenic steam generation (H2 + O2 torch) for wet oxidation. Thickness control: Controlled by temperature, time, and ambient. Reproducibility within angstroms for gate oxide. Si consumption: Approximately 44% of final oxide thickness comes from consumed silicon. Important for dimensional control. Chlorine addition: Small amounts of HCl or TCA added to getter metallic contamination and improve oxide quality. Equipment: Same furnace platforms as diffusion (Kokusai, TEL). Dedicated tubes for oxidation to prevent cross-contamination.