Process design for ultra-low Si damage by suppressing diffusive point defects

Abstract This study investigated the formation and distribution of Si interstitial (I1) and its clusters that are generated by ion bombardment during plasma etching. PL, in-situ XPS, and DLTS analyses revealed that I1 and its clusters were extensively distributed over a 100um region from the etched Si trench and interacted with other defects such as vacancy and oxygen (O) in N-type Si substrates. Numerical modeling of their generation and reactive diffusion indicated that their distribution depended on the O density in the Si substrate and absolute I1 density, suggesting that optimizing the O density is crucial for low Si damage. The simulated temperature dependence of I1 distribution showed that a temperature of -150 ºC localized the diffusive I1 to within a 4 nm region. Removing this region by an after-treatment while maintaining the same temperature can help realize ultra-low Si damage without annealing recovery for high-performance advanced CMOS devices and image sensors.