Precise EOT regrowth extraction enabling performance analysis of Low Temperature Extension First devices

Jessy Micout (1, 2) , Quentin Rafhay (2) , Xavier Garros (1) , Mikael Cassé (1) , Jean Coignus (1) , Luca Pasini (1, 3, 2) , Cao-Minh Vincent Lu (1) , Nils Rambal (1) , Claire Fenouillet-Beranger (1) , Laurent Brunet (1) , Giovanni Romano (3) , Rémy Gassilloud (1) , Perrine Batude (1) , Maud Vinet (1) , Gérard Ghibaudo (2)

1 CEA-LETI - Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information
2 IMEP-LAHC - Institut de Microélectronique, Electromagnétisme et Photonique - Laboratoire d'Hyperfréquences et Caractérisation
3 STMicroelectronics

— 3D sequential integration requires top FETs processing with a low thermal budget (500°C). The analysis of the origin of the performance difference between Low Temperature (LT) MOSFET and high temperature standard process must take into account a potential EOT modification for short gate lengths. In this work, the difficulty of precise EOT extraction for scaled devices is observed by CV measurements and an alternative methodology using IV measurements is proposed. This methodology has been applied to an extension first integration, and the extraction accuracy is high enough to conclude to an EOT regrowth for the low temperature nFETs only. Thus, the origin of performance degradation between LT and HT, previously attributed to larger access resistance, highlights also a detrimental role of gate stack instability. The origin of this variation is attributed to oxygen ingress, through the thin extension first liner which should be suppressed by minor process optimizations.

Domains: Micro and nanotechnologies/Microelectronics

Jessy Micout, Quentin Rafhay, Xavier Garros, Mikael Cassé, Jean Coignus, et al.. Precise EOT regrowth extraction enabling performance analysis of Low Temperature Extension First devices. 2017 ESSDERC - 47th European Solid-State Device Research Conference, Sep 2017, Leuven, Belgium. pp.144-147, ⟨10.1109/ESSDERC.2017.8066612⟩. ⟨cea-01525266⟩