Investigation of boron penetration through decoupled plasma nitrided gate oxide using backside secondary ion mass spectrometry depth profiling

High drive-in temperature during dopant activation of $p+$-poly metal-oxide-semiconductor field effect transistors causes boron penetration through the thin gate oxide, which degrades the device performance. Conventional secondary ion mass spectrometry (SIMS) depth profiling is unable to accurately analyze boron penetration under rapid thermal annealing conditions due to ion knock-on and mixing effects. With the development of backside SIMS depth profiling technique using SOI wafers [Yeo et al., Surf. Interface Anal. 33, 373 (2002); Runsheim et al., J. Vac. Sci. Technol. B 20, 448 (2002)], quantification of the amount of boron penetration becomes possible. In this article, boron penetration through decoupled plasma nitridation silicon dioxide was studied by performing both front and backside depth profiling using 0.5 keV $O2+$ with oxygen flooding and 2 keV $Cs+$ primary ions at oblique incidence in a Cameca IMS-6f SIMS instrument.