Characterization of the distribution of defects introduced by plasma exposure in Si substrate

Defects in a silicon (Si) substrate induced by plasma exposure—plasma-induced damage (PID)—were investigated using various techniques. The authors performed a comprehensive characterization of plasma induced damages, which will be indispensable for suppressing PID, by precisely assigning the density profile of defects in the region to ∼1016 cm−3. In this study, the Si substrate was damaged using an electron cyclotron resonance plasma system. Cathodoluminescence analysis was used to detect the defects in the damaged Si substrates. The thickness of the damaged layer in the Si substrates was determined to be approximately 1–2 nm by transmission electron microscopy and spectroscopic ellipsometry, while time-of-flight secondary ion mass spectrometry identified the presence of interstitial atoms to a depth of ∼20 nm. Positron annihilation spectroscopy showed that the structural changes related to vacancies interacting with C and F atoms were distributed from the substrate surface to a depth of approximately 130 nm. The authors further verified this finding by a technique using the PID-enhanced dechanneling of As atoms implanted with a projection range of 10 nm. After plasma exposure, the difference between the plasma-damaged and the nondamaged samples in the injected As profiles was identified to a depth of ∼130 nm with a density of ∼1016 cm−3. The comprehensive defect profiling performed in this study provides key guidelines for the introduction mechanism of defects in plasma exposed Si before designing future electronic devices.