Generation of deep levels in silicon under posthydrogen-plasma thermal anneal

Si wafers subject to short-time (4-12 min), low-temperature atomic hydrogen cleaning in an electron-cyclotron-resonance plasma system have been annealed subsequently in the temperature range 300-750°C for 20 min. While only a small broad peak is discernible immediately after hydrogenation, several pronounced and distinct majority-carrier trap levels appear in deep-level transient spectroscopy measurements of subsequently fabricated Schottky diodes on both n- and p-type Si samples annealed at 450°C and above. The concentrations peak 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.