Influence of interface relaxation on passivation kinetics in H2 of coordination Pb defects at the (111)Si/SiO2 interface revealed by electron spin resonance

Abstract

P b -type interface defects in (100) Si/SiO 2 structures grown in ozonated water solutionElectron spin resonance studies have been carried out on the isothermal passivation kinetics in 1 atm molecular H 2 of trivalent Si traps (P b s;Si 3 wSi • ͒ at the interface of thermal (111)/Si/SiO 2 as a function of oxidation temperature T ox in the range 250-1100°C. Interpretation within the generalized simple thermal ͑GST͒ passivation model, based on first-order interaction kinetics, reveals a distinct increase in spread E f in the activation energy for passivation E f with decreasing T ox ͑ϳ3 times in the covered T ox window͒, while the other key kinetic parameters ͑E f , preexponential factor͒ remain essentially unchanged. The variation in E f is ascribed to differently relaxed interfacial stress, affecting the spread in P b defect morphology. In a second analytic part, the impact of the variation in E f , and correlatively in the activation energy E d for P b H dissociation, on P b -hydrogen interaction kinetics is assessed within the GST-based full interaction scheme, describing parallel competing action of passivation and dissociation. In particular, the passivation behavior in 1 atm H 2 of an initially exhaustively depassivated P b system, is analyzed exposing, as a major result, that growing spreads E f , E d result in a drastic reduction in passivation efficiency ͑drop by four orders of magnitude for a threefold increase in E f ͒. For E f /E f տ20%, the P b system cannot be inactivated beyond the 90% level, incompatible with device quality requirements. Heating time/temperature vs spread conditions for optimum passivation in H 2 have been established, and the technological impact of altering E f , E d is discussed. At film edges and trench corners, which are vulnerable local regions of exces stress, and hence enhanced E f , E d , an edge defeat effect with respect to passivation is exposed. Within the relentless scaling of Si-based integrated circuit devices, the growing relative impact of edge regions may jeopardize proper passivation of interface traps in the conventional way in future device generations.

Analysis of defects at the interface between high-k thin films and (100) silicon

“…Work on SiO 2 [6] has shown that, for fixed anneal conditions, defects in films produced with low T ox of 250 o C are passivated to a much lesser extent than films with a higher T ox . This is attributed to higher levels of interface stress in these low temperature films, which leads to a variation in P b morphology between individual sites, creating a spread in the passivation activation energies [6,7]. This results in a proportion of sites, with high activation energies, that are not passivated by a standard anneal.…”

Electron paramagnetic resonance evaluation of defects at the (100)Si/Al2O3interface

“…This reduced annealing passivation efficiency and the high [P b0 ]/[P b1 ] ratio seen in these films are also observed in thermal SiO 2 grown with low oxidation temperatures [15,16]. The effects seen are perhaps, therefore, associated with a SiO 2 interface layer.…”

“…Work on SiO 2 [16] has shown that for fixed anneal conditions, defects in films produced with low oxidation temperatures, T ox , of 250 o C are passivated to a much lesser extent than films with a higher T ox . This is attributed to higher levels of interface stress in these low temperature films, which leads to a variation in P b morphology between individual sites, creating a spread in the passivation activation energies [16,17]. This results in a proportion of sites, with high activation energies, that are not passivated by a standard anneal.…”

Chemical kinetics of the hydrogen-GePb1 defect interaction at the (100)GexSi1−x/SiO2 interface

“…The reaction kinetics scheme of GeP b1 passivation in H 2 and GeP b1 -H dissociation is consistently described by the GST model 9,10 in which the kinetics of the passivation and dissociation reactions are described by the following rate equations:…”

“…7,8 The kinetics of interaction with hydrogen (passivation/depassivation) of Si P b defects are well described by a generalized simple thermal (GST) model. 9,10 At first sight, one might expect a close similarity for seemingly isomorphic semiconductor/insulator interfaces such as the Ge/Ge-oxide system. However, the latter interface generally exhibits a high density of (various) differently behaving interface traps 11,12 and, as demonstrated by ESR, part of these include Ge DB-type interface defects.…”