Segregation and transport coefficients of impurities at the Si/SiO2 interface

Abstract

Segregation and transport coefficients of impurities at the Si/SiO2 interface have been studied. A brief model has been proposed which relates the two coefficients to the oxidation rate and the impurity concentrations at both sides of a Si/SiO2 interface. The model enables us to obtain the transport coefficients from the measured impurity profiles for the first time. The transport coefficients of arsenic and phosphorus are, for example, 0.12 and 5.0 μm/min at 1100 °C, respectively. The segregation coefficients can be also calculated from this model. They are more than 1000 for arsenic and phosphorus, and less than 1 for boron at 1000–1100 °C.

Analyses of the As doping of SiO2/Si/SiO2 nanostructures

“…No As segregation effect from the SiO 2 layers to the Si layers is observed. This is different from the case of an oxidation process of As-implanted Si bulk in which the moving Si/SiO 2 interface determines the As segregation in the Si [7]. To study in detail the accumulation process of the As at the Si/SiO 2 interfaces we report in Fig.…”

“…in bulk Si and SiO 2 has been widely investigated in the last decades. In particular, it is known [7] that in As implanted bulk Si, an oxidation process determines the As segregation in Si (with a segregation coefficient Κ≈2000). Starting from these results, in this work, we illustrate the behaviour of As when it is confined, by the implantation technique, in a SiO 2 (70nm)/Si(30nm)/SiO 2 (70nm) multilayer and its spatial redistribution when annealing processes are performed.…”

Effect of Thermal Oxidation on the Segregation of Phosphorus Implanted into Silicon

“…The accuracy in experimental studies of impurity segregation can be improved by analyzing SIMS depth profiling results for the SiO 2 -Si system in a numerical diffusion-segregation model. Free of limitations inherent in analytical models [3][4][5], numerical simulation of diffusion-segregation processes during the thermal oxidation of phosphorus-ion-implanted silicon layers must take into account a number of concomitant effects: the influence of thermal oxidation on impurity diffusion, transient enhanced diffusion of the impurity in the ion-implanted layer, and, at high doping levels, the polytropy and NCP effects.…”

“…According to their results, increasing the temperature of oxidizing annealing from 1000 to 1100 ° C increases m s from 1900 to 2750. Modeling the phosphorus distribution in SiO 2 , Sakamoto et al [4] assumed segregation to be a nonequilibrium process and neglected the impurity diffusion in silicon and phosphorus pile-up in a thin ( ~10 nm) surface layer of silicon, the so-called near-surface concentration peak (NCP).…”

“…Sakamoto et al [4] used SIMS characterization to determine the m s of phosphorus at the SiO 2 /Si(100) interface as a function of temperature during annealing in a dry oxygen atmosphere. According to their results, increasing the temperature of oxidizing annealing from 1000 to 1100 ° C increases m s from 1900 to 2750.…”