TiN/titanium–aluminum oxynitride/Si as new gate structure for 3D MOS technology

Titanium–aluminum oxynitride (TAON) has been used as high-k gate dielectric for planar MOS devices (capacitors and transistors) and obtained by Ti/Al e-beam evaporation, with additional electron cyclotron resonance (ECR) plasma oxynitridation on Si substrates. Thus, planar MOS (Al/TAON/Si) capacitors were characterized by TEM and EDS analyses, and the film formation with thickness of 6.7 nm and with Ti, Al, O and N into the TAON dielectric bulk is confirmed. However, for future 3D device technology application, these films have been not investigated. So, 3D MOS capacitors with Al/TAON/Si (as control sample) and TiN/TAON/Si gate structures for 3D technology were fabricated. Al/TAON and TiN/TAON layers on 3D gate region must present conformal coverage, which is a mandatory requirement for 3D transistors, such as FinFET. To characterize the TAON conformal coverage for this technology, the gate structure formed by Al/TAON/Si for FinFETs were fabricated and the “Fin” structures were obtained using a Focused Ion Beam (FIB) system to become thinner the width of active area to get the “Fin” structure. C–V curves of these structures were performed at 1 MHz, and the three C–V curve regions (accumulation, depletion and inversion) are well defined for all capacitors, indicating that the conformal coverage on the 3D and FinFET gate regions can be occurred. Furthermore, these results indicated that TiN/TAON layers can be used as a new alternative for 3D MOS structures.

3D MOS capacitors with Al/TAON/Si (as control sample) and TiN/TAON/Si gate structures for 3D technology were fabricated. Focus Ion Beam (FIB) thinning process: (a) the active area definition; (b) during Fin thinning process; (c) after Fin thinning; (d) Fin structures in detail; (e) after Al/TAON/Si structure fabrication; (f) Al/TAON/Si Fin structure in detail. All pictures were obtained by electron beam of FIB system.Figure optionsDownload as PowerPoint slide