Generation of Deep Levels in Silicon under Post-Hydrogen-Plasma Thermal Anneal

Si wafers subject to short-time (4-12 min.), low-temperature atomic hydrogen cleaning in an electron cyclotron resonance (ESR) plasma system have been annealed subsequently in the temperature range 300-750 °C for 20 mins. While only a small broad peak is seen immediately after hydrogenation, several pronounced and distinct majority carrier trap levels show up in deep level transient spectroscopy (DLTS) measurements of subsequently fabricated Schottky diodes on samples annealed at 450 °C and above. These appear to be related to thermal donors, with their formation rate greatly enhanced by the pre-anneal atomic hydrogenation. The concentrations of these levels drop substantially after the 750 °C anneal.