Silicide Formation Process of Er Films with Ta and TaN Capping Layers

Abstract

The phase development and defect formation during the silicidation reaction of sputter-deposited Er films on Si with ∼20-nm-thick Ta and TaN capping layers were examined. TaN capping effectively prevented the oxygen incorporation from the annealing atmosphere, which resulted in complete conversion to the ErSi2-x phase. However, significant oxygen penetration through the Ta capping layer inhibited the ErSi2-x formation, and incurred the growth of several Er-Si-O phases, even consuming the ErSi2-x layer formed earlier. Both samples produced a number of small recessed defects at an early silicidation stage. However, large rectangular or square-shaped surface defects, which were either pitlike or pyramidal depending on the capping layer identity, were developed as the annealing temperature increased. The origin of different defect generation mechanisms was suggested based on the capping layer-dependent silicidation kinetics.

Formation of Er‐germanosilicide films on strained Si1−xGex with different Ge contents

“…Hereafter, the crystalline Er‐silicide and Er‐germanosilicide phases formed on Si and Si 1− x Ge x are denoted as ErSi 2− y and Er(Si 1− z Ge z ) 2− y , respectively, for convenience. The phase‐transition temperature of ErSi 2− y for the reference sample (Er/Si sample) coincides well with that in our previous study and other references . In addition, we could not observe a significant effect of the Ge concentration of Si 1− x Ge x on the phase transition sequence of the Er film during annealing.…”

“…For the reference sample prepared on a Si substrate (Fig. a), the observed cross‐sectional microstructure reflects well‐established Er‐silicidation kinetics: out‐diffusion of Si atoms from the substrate, followed by the formation of an amorphous Er–Si mixed layer and subsequent nucleation/growth of crystalline ErSi 2− y from the interface between the Er–Si mixed layer and Si substrate . A similar microstructural evolution was also observed in the Si 0.72 Ge 0.28 sample, as shown in Fig.…”

“…In this paper, in order to exclude the oxidation effect on the formation of Er‐germanosilicide, we adopted a TaN capping layer, which was proven in our previous study to effectively block the ambient oxygen diffusion . The Er‐germanosilicide‐forming process was carefully scrutinized on the epitaxially‐grown, strained Si 1− x Ge x layers with different Ge concentrations.…”

Defect-Free Erbium Silicide Formation Using an Ultrathin Ni Interlayer

“…These temperatures correspond to the partial and near-complete conversion to erbium silicide of the sample without a Ni interlayer (reference sample), as verified in our previous report. 10 In addition to many smallsized surface pits with a high density, the reference sample possesses a number of large-sized, recessed defects of a square shape, even when exposed to an annealing temperature of 500°C , as shown in Figure 1a,b. In contrast, samples with a Ni interlayer exhibit a clean surface free of notable defects under identical annealing conditions, as shown in Figure 1c,d.…”

Prediction of Stable Ruthenium Silicides from First-Principles Calculations: Stoichiometries, Crystal Structures, and Physical Properties

“…Transition-metal silicides have been studied theoretically and experimentally for a long time. − The study of their metallographic and electronic structures is particularly interesting, as they can exhibit novel physical properties such as high thermal stability, good conductivity, and low chemical reactivity. ,,, Their stability and oxidation resistance make these silicides excellent high-temperature structural materials, for instance, for advanced aerospace applications. , Their relatively low electrical resistance has been utilized in microelectronics for the development of integrated circuit technology and design of microelectronic devices . Until now, some 3d transition metal silicides, ,,, such as CrSi and MnSi, have been studied in detail, both theoretically and experimentally, whereas data on the 4d transition metal silicides is quite limited, and some problems are still unresolved, especially for ruthenium silicides.…”