Factors influencing the purity of electronic grade phosphine delivered to MOCVD tools

Abstract Increasing mobility of InP films with usage time of one PH 3 cylinder prompted an investigation into factors influencing the purity of delivered PH 3 . The presence of hygroscopic H x PO y residues in a delivery system greatly increases the dry-down time compared to that of a clean system. Static delivery system tests show increasing H 2 O concentration with time and twice the increase in PH 3 versus N 2 over 48 h indicating reaction of metal oxides in components with PH 3 to generate H 2 O. Gas purity may also vary during cylinder usage. Depletion of a high-purity PH 3 cylinder shows consistently low gas phase H 2 O levels before phase-break but increasing levels after phase-break, as the cylinder depressurizes. The results highlight the importance of using pure PH 3 , employing rigorous cycle-purging procedures to prevent H x PO y contamination, switching out cylinders in good time and using purification technology to control H 2 O.