Physicochemical Characterization of Passive Films and Corrosion Layers by Differential Admittance and Photocurrent Spectroscopy

Two different electrochemical techniques, differential admittance and photocurrent spectroscopy, for the characterization of electronic and solid state properties of passive films and corrosion layers are described and critically evaluated. In order to get information on the electronic properties of passive film and corrosion layers as well as the necessary information to locate the characteristic energy levels of the passive film/electrolyte junction like: flat band potential (Ufb), conduction band edge (EC) or valence band edge (EV), a wide use of Mott-Schottky plots is usually reported in corrosion science and passivity studies. It has been shown, in several papers, that the use of simple M-S theory to get information on the electronic properties and energy levels location at the film/electrolyte interface can be seriously misleading and/or conflicting with the physical basis underlying the M-S theory. A critical appraisal of this approach to the study of very thin and thick anodic passive film grown on base-metals (Cr, Ni, Fe, SS etc..) or on valve metals (Ta, Nb, W etc..) is reported in this work, together with possible alternative approach to overcome some of the mentioned inconsistencies. At this aim the theory of amorphous semiconductor Schottky barrier, introduced several years ago in the study of passive film/electrolyte junction, is reviewed by taking into account some of the more recent results obtained by the present authors. Future developments of the theory appears necessary to get more exact quantitative information on the electronic properties of passive films, specially in the case of very thin film like those formed on base metals and their alloys. The second technique described in this chapter, devoted to the physico-chemical characterization of passive film and corrosion layers, is a more recent technique based on the analysis of the photo-electrochemical answer of passive film/electrolyte junction under illumination with photons having suitable energy. Such a technique usually referred to as Photocurrent Spectroscopy (PCS) has been developed on the basis of the large research effort carried out by several groups in the 1970’s and aimed to investigate the possible conversion of solar energy by means of electrochemical cells. In this work the fundamentals of semiconductor/electrolyte junctions under illumination will be highlighted both for crystalline and amorphous materials. The role of amorphous nature and film thickness on the photo-electrochemical answer of passive film/solution interface is reviewed as well the use of PCS for quantitative analysis of the film composition based on a semi-empirical correlation between optical band gap and difference of electronegativity of film constituents previously suggested by the present authors. In this frame the results of PCS studies on valve metal oxides and valve metal mixed oxides will be discussed in order to show the validity of the proposed method. The results of PCS studies aimed to get information on passive film composition and carried out by different authors on base metals (Fe, Cr, Ni) and their alloys, including stainless steel, will be also compared with compositional analysis carried out by well-established surface analysis techniques

P-type trigate nano wires: Impact of nano wire thickness and Si<inf>0.7</inf>Ge<inf>0.3</inf> source-drain epitaxy

session 1: Nanowires and NanosensorsInternational audienceThe impact of nanowire (NW) height and Si 0.7 Ge 0.3 :B source-drain (S/D) on the performance of p-type trigate NW is presented. We show that an increase in Si NW height from 14.5nm to 24nm generates up to +30% enhancement in hole effective mobility for a 13nm NW width. Effectiveness of Sio.7Geo.3:B S/D is then discussed for a wide range of NW width (13nm<;W<;218nm) and height (11nm<;H Nw <;24nm). We also highlight short-channel performance of trigate NW with Si 0.7 Ge 0.3 :B S/D: +86% I on improvement is observed for H Nw =11nm against only +58% for H Nw =24nm

Stacked-Nanowires and FinFET Transistors: Guidelines fo the 7nm Technology

International audienc

Stacked Nanowires FETs: Mechanical robustness evaluation for sub-7nm nodes

session 8: advanced CMOS and New Devices ConceptsInternational audienceStacked Nanowires FETs are proposed to replace FinFET and FDSOI for sub-7nm nodes. While most studies demonstrate the performances gain offered by such structures, mechanical stability of the suspended silicon channels needs to be considered. This paper provides a fully mechanical analytical description of nanowire stacks to explain the occurrence of buckling phenomena of silicon channels

Ω-Gate Nanowire Transistors Realized by Sidewall Image Transfer Patterning: 35nm Channel Pitch and Opportunities for Stacked-Nanowires Architectures

SSDM Young Researcher AwardInternational audienc

HSQ Lithography for Nanowire First Integration: an Interesting Alternative for Gate Last Fabrication of Sub-7nm Stacked Nanowire FETs.

International audienc

(Invited) Evaluation of Stacked Nanowires Transistors for CMOS: Performance and Technology Opportunities

session New Device Architectures (G02-1168)International audienc

Hydrogen silsesquioxane tri-dimensional advanced patterning concepts for high density of integration in sub-7 nm nodes

Best paper award; session 9: Novel Materials and TechnologiesInternational audienceRecent developments in CMOS devices such as FinFET, FDSOI or stacked nanowire FETs (SNWFETs) have led the industry to consider increasingly complex integration processes while aiming at smaller and smaller devices. This paper proposes new concepts of device integration based on the use of hydrogen silsesquioxane (HSQ). Recently employed to replace polysilicon sacrificial gate in gate last processes, its use could also be extended for building the whole transistor level including device lateral insulation, multi-workfonction layouts, self-aligned contacts and possibly the first layer of metal interconnects. If several EUV masks could be employed for such a use, HSQ patterning once enhanced by multi-electron beam lithography, could allow to perform all these features within a single exposure step without involving any conventional etching or stripping steps