Frequently Asked Questions

Electronic grade IPA is purified to SEMI C1 standard levels with total metallic impurities below 50 ppb (G1) to 0.1 ppb (G5), liquid particle counts below 500 ct/mL (G1) to 5 ct/mL (G5), and water content below 500 ppm (G1) to 5 ppm (G5). Industrial grade IPA contains metals at ppm levels with no particle specification — unsuitable for semiconductor device fabrication where sub-ppb metal contamination causes yield loss.

SEMI C1 defines five electronic grade tiers: G1 (≥99.0%, metals ≤50 ppb) for PCB and display; G2 (≥99.9%, ≤10 ppb) for mature 180nm+ nodes; G3 (≥99.99%, ≤2 ppb) for 45–180nm; G4 (≥99.999%, ≤0.5 ppb) for 7–45nm; G5 (≥99.9999%, <0.1 ppb) for sub-7nm, EUV, and Marangoni drying. Each tier verified by ICP-MS (28 elements), in-line LPC, and Karl Fischer titration.

SEMI C12 applies specifically to photoresist process solvents. Beyond C1 metal and particle limits, C12 adds: acidity as acetic acid (≤20 ppm G4); peroxide content as H₂O₂ (≤1 ppm G4); color (APHA ≤5 G4); specific impurities (residual PGME in PGMEA ≤50 ppm G4); and photoresist compatibility testing. PureTech PGMEA G4/G5 is fully SEMI C12 certified.

A compliant CoA must include: lot number and date; claimed SEMI tier (G1–G5); GC assay (actual % not just pass/fail); individual ICP-MS data for all 28 elements with actual measured values in ppb; LPC particle count (actual count ± uncertainty); Karl Fischer water; instrument serial numbers and calibration dates; analyst signature and QA release. Pass/fail statements without actual data are insufficient for semiconductor QMS qualification.

Marangoni drying uses the surface tension difference between IPA (22 mN/m) and water (72 mN/m) to sweep water off wafers without droplet evaporation. G5 IPA is required because: (1) water ≤5 ppm maintains maximum surface tension gradient; (2) acetone ≤1 ppm prevents Marangoni flow instability; (3) metals <0.1 ppb prevents surface metal deposition. Lower grades cause watermarks, stiction, and metal contamination.

LiPF₆ reacts with water to form HF: LiPF₆ + H₂O → LiF + POF₃ + 2HF. Even 20 ppm water in DMC generates enough HF to attack the NMC cathode surface, dissolve transition metals, degrade the SEI layer, and corrode aluminum current collectors. G4 DMC (≤20 ppm H₂O) is the minimum for EV applications; G5 (≤10 ppm) for premium cells. All DMC must be stored in dry rooms (dew point ≤-40°C) after opening.

PureTech supplies: 1L/4L bottles (R&D qualification), 18–20L carboys (small fab/pilot), 200L drums (standard production), 1000L IBCs (high-volume), bulk tanker (gigafactory). G4/G5 grades use N₂ blanket fill. Minimum order: 200L for production grades; 1L for qualification. Blanket purchase agreements with weekly IBC delivery for fabs consuming >20 MT/month.

Standard protocol: (1) CoA review — verify all parameters against fab spec; (2) Incoming QC — split-sample analysis of 3 lots; (3) Process qualification — 25 wafers through target process, measure particle count, metal contamination by TXRF/VPD-ICP-MS, film uniformity; (4) Statistical comparison — demonstrate equivalence to qualified incumbent; (5) Safety stock — 30-day minimum. Typical timeline: 6–16 weeks depending on process sensitivity.