Electronic defects induced in p- and n-type silicon by SF6 plasma etching

Abstract

Electronic defects induced in p- and n-type silicon by SF6 plasma etching in microwave multipolar plasma reactors have been studied by capacitance spectroscopy, spreading resistance, and infrared absorption measurements. A passivation of the boron and phosphorus electrical activity is associated with hydrogen contamination due to residual water traces in the reactor. Deep level transient spectroscopy measurements reveal several deep levels in the gap after etching. They are located at 0.51 and 0.36 eV above the valence band in the p-type boron-doped silicon and at 0.4 and 0.24 eV below the conduction band in the n-type phosphorus-doped silicon. We studied the influence of plasma parameters, gas nature, and postetch thermal annealing on the H(0.51), H(0.36), E(0.4), and E(0.24) levels. The results show that the occurrence of the H(0.51) and E(0.4) levels is correlated with displacement damage production and the presence of SFx species in the plasma. The H(0.36) level is caused by the formation of a carbon-interstitial-related defect whereas the E(0.24) level is attributed to the V–V divacancy.