Comparison of Selective Deposition Techniques for Fabricating p+n Ultrashallow Silicon Diodes

Ultrashallow diodes were fabricated using two different chemical-vapor deposition techniques: either a pure boron (PureB) deposition from diborane or boron-doped Si selective epitaxial growth (SEG) from dichlorsilane and diborane gases. They are evaluated with respect to the current-voltage diode characteristics. The PureB diodes have two decades lower saturation current, good uniformity and no significant leakage currents. In contrast the SEG diodes have leakage currents that cause a factor 10 spread in saturation current. A differential current measurement technique was applied to show that the high SEG-diode saturation currents are a result of high electron injection in the anode region and the spread is due to defectrelated leakage currents originating in the vicinity of the p+-region