Vacancy-Type Defects Introduced by Gas Cluster Ion-Implantation on Si Studied by Monoenergetic Positron Beams

Abstract

Vacancy-type defects in Ar and B gas cluster ion-implanted Si were probed by monoenergetic positron beams. The acceleration energy of the clusters ranged between 20–60 keV, and the mean cluster size was 2×103 atoms. Doppler broadening spectra of the annihilation radiation were measured, and the vacancy-rich region was found to localize at a depth of 0–13 nm. Measurements of the lifetime spectra of positrons revealed that two different defect species coexisted in the damaged region introduced by Ar gas cluster implantation, and these were identified as divacancy-type defects and large vacancy clusters filled with Ar. The formation of the vacancy clusters was attributed to extremely high temperature and its rapid transients in impact regions of Ar cluster ions. For B gas cluster ion implanted Si, the detected momentum distribution of electrons in the damaged region was broader than that in the defect free Si, suggesting that the trapping of positrons by open spaces adjacent of B clusters.

Impact of back-grinding-induced damage on Si wafer thinning for three-dimensional integration

“…The theoretical explanation of positron annihilation spectroscopy is mentioned in the literature. 20,21,26) When a positron is implanted into condensed matter, it annihilates with an electron and emits two 511 keV £ quanta. The energy distribution of the annihilation £ rays is broadened by the momentum component of the annihilating electron-positron pair pL, which is parallel to the emitting direction of the £ rays (Fig.…”

“…In particular, positron annihilation is a superior technique for detecting vacancy-type defects in semiconductors. [19][20][21][22] Since the atomic-level vacancy-type defects are detectable not only on the wafer surface but also inside a wafer, it is useful to evaluate the voids penetrating a wafer caused by thinning.…”