ECR hydrogen plasma treatment of Si: defect activation under 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. The concentrations of these deep levels reach a maximum at anneal temperatures around 500°C and drop substantially beyond 750°C. This phenomenon appears to be unrelated to the presence of oxygen in Si and is of potential importance in silicon processing technology.