NiSi Thin Films Research Articles

The application of NiCrPt alloy targets for magnetron sputter deposition: Characterization of targets and deposited thin films

NiSi thin films are extensively used in advanced semiconductor devices due to their desirable electrical properties. Recently, the incorporation of platinum (Pt) into NiSi thin films, resulting in NiPtSi, has been pursued to mitigate the agglomeration of NiSi and delay its transformation into NiSi2. Typically, in semiconductor manufacturing, NiPt films are deposited onto silicon wafers through magnetron sputtering using NiPt sputtering targets. To further enhance the properties of these thin films, chromium (Cr) was introduced into the NiPt target. Initially, NiCrPt targets were fabricated through thermal mechanical treatment. Subsequently, NiCrPt thin films were deposited via magnetron sputtering using these NiCrPt targets. The study results indicate that, in comparison to NiPt targets, the addition of chromium offers several advantages: (1) it refines the grain size of NiPt in both bulk and thin film states; (2) it effectively reduces microcracks in the thin films; and (3) it increases the sputtering rate of NiCrPt targets, owing to an increased pass-through flux of 100 % and the refined grain size of the NiCrPt target. These findings provide valuable insights into the design and development of NiPt alloy sputtering targets and the production of crack-free thin films via magnetron sputtering, marking a significant advancement in the field of semiconductor manufacturing.

Influence of the annealing schemes on the formation and stability of Ni(Pt)Si thin films: Partial, laser, total, and one-step annealings

In this study, the impact of various annealing schemes on the formation and agglomeration mechanisms of ultrathin Ni(Pt)Si films is investigated. To this end, 11 ± 1 nm-thick Ni(Pt)Si films are grown on 300 mm Si(100) wafers using various traditional rapid thermal annealing procedures as well as laser annealing. The obtained silicide films are then subjected to additional annealing between 500 and 800 °C, to evaluate their stability at high temperature. The correlation between the as-grown Ni(Pt)Si film properties and their capability to withstand agglomeration is analyzed via a complementary approach of several techniques (Rs, ellipsometry, TEM-EDX, SEM, and EBSD). Texture comparison for ultrathin films give deeper insights into the role of the NiSi-(010) and NiSi-(013) orientations in the agglomeration phenomenon. Depending on the annealing schemes used during the silicide formation, there is a strong correlation between the initial microstructure of Ni(Pt)Si films and their subsequent degradation. Indeed, cross-analysis of these different key parameters indicates that the presence of small Ni(Pt)Si grains (40 nm) obtained after laser annealing, and a high ratio of Ni(Pt)Si grains oriented along the (013) direction appears to be more efficient in delaying the agglomeration to higher temperatures.

High-Temperature Failure Evolution Analysis of K-Type Film Thermocouples.

Ni90%Cr10% and Ni97%Si3% thin-film thermocouples (TFTCs) were fabricated on a silicon substrate using magnetron sputtering technology. Static calibration yielded a Seebeck coefficient of 23.00 μV/°C. During staged temperature elevation of the TFTCs while continuously monitoring their thermoelectric output, a rapid decline in thermoelectric potential was observed upon the hot junction reaching 600 °C; the device had failed. Through three cycles of repetitive static calibration tests ranging from room temperature to 500 °C, it was observed that the thermoelectric performance of the TFTCs deteriorated as the testing progressed. Utilizing the same methodology, Ni-Cr and Ni-Si thin films corresponding to the positive and negative electrodes of the TFTCs were prepared. Their resistivity after undergoing various temperature annealing treatments was measured. Additionally, their surfaces were characterized using Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). The causes behind the decline in thermoelectric performance at elevated temperatures were analyzed from both chemical composition and microstructural perspectives.

Broad spectral response to photon energy unlimited by Schottky barrier from NiSi/Si junction

Recent advances in plasmonic absorption devices offer a novel approach for extending the range of silicon light detection. This is achieved by exploiting the Schottky interface energy barrier, which overcomes the limitation of the 1.12 eV photon energy conversion imposed by the silicon intrinsic bandgap. Internal photoemission has been widely accepted as the primary emission mechanism, which is mostly limited by the Schottky barrier height. However, we have discovered that carriers with energy lower than the Schottky barrier can generate electrical responses through the photothermal effect, breaking this restriction. In this study, we closely investigate two forms of photoresponses, namely photoelectric and photothermal, on a NiSi thin film Schottky photodetector, considering various factors such as temperature, applied bias, incident power, and wavelength regime. Without photothermal assistance, the device achieves a responsivity of 0.41 mA/W to a 1550 nm laser. Under bias-driven conditions, highly energized hot carriers generate a 2.18 μA photoelectric response, while a 0.861 μA photothermal response is simultaneously observed under 6 mW 1550 nm laser illumination. Through systematic investigation, we advance the mechanism of both responses by combining the hot carrier model and the Schottky barrier diagram. Finally, we experimentally obtain a 4.85 μA sheer photothermal response to a 0.475 mW 4-μm wavelength signal with 10.21 mA/W responsivity. It is expected that the device will also show responses to longer wavelengths.

On the influence of Ni(Pt)Si thin film formation on agglomeration threshold temperature and its impact on 3D imaging technology integration

Ni(10 at.% Pt) monosilicide is used as contact in microelectronics but suffers from degradation at relatively low temperatures due to agglomeration. Recent results obtained on 28 nm-FDSOI (Fully Depleted Silicon On Isolator) microelectronics devices have demonstrated severe yield loss after an anneal at 550 °C/2 h linked to Ni(Pt)Si film dewetting. Such agglomeration thermal budget is 100 °C lower than the ones measured on blanket wafers with in-situ or ex-situ four-point probe measurements. In this context, the aim of this paper is to investigate the effect Ni(Pt)Si formation process on the Ni(Pt)Si agglomeration using different approaches as (i) the classical one in which one anneal is applied to form silicide and leads also to agglomeration, (ii) the silicide formation through the standard SALICIDE process, “Self-Aligned Silicide”, and a subsequent anneal to induce agglomeration, and (iii) the standard SALICIDE process for silicide formation followed by an encapsulation of the top silicide surface by a SiN layer as applied in devices, and submitted finally to the agglomeration anneal. Our work demonstrated that the film thermal stability is influenced by the sequencing of the Selective Etch (SE) in the formation process and whether it is formed by a single or a double anneal. For single anneal, the thermal budget needed to agglomerate Ni(Pt)Si film is higher i.e., agglomeration occurs at around 700 °C/30 s in single anneal as compared to double anneal at around 550 °C/30 s. Another conclusion of this work is that four-point probe measurements are not sensitive enough to well estimate the real starting point of agglomeration phenomenon which is detrimental for devices (holes formation at the triple junctions). Some additional characterizations such as tilted Scanning Electron Microscopy (tilted SEM) are deeply needed for an accurate determination of agglomeration thermal budget. This study allows clarifying the main parameters leading to agglomeration: the film thickness and the grain size appear to be the more important ones.

Dewetting of Ni silicide thin film on Si substrate: In-situ experimental study and phase-field modeling

In this paper, the in-situ Scanning Electron Microscopy (in-situ SEM) technique and three-dimensional (3-D) phase-field simulation were combined to perform a comprehensive study on the kinetics and mechanisms of dewetting (or agglomeration) of a 30 nm NiSi films on Si(100) substrate at 600 °C. The evolution of texture during agglomeration of the polycrystalline NiSi thin film was also studied by ex-situ Electron BackScattered Diffraction (EBSD). The phase-field simulation results showed that abnormal grain growth plays an important role in the dewetting process of polycrystalline films, while the misorientations between the NiSi grains and the Si substrate are the main reason for the agglomeration of NiSi polycrystalline thin film on the monocrystal Si substrate. Moreover, 3-D phase-field simulations coupled with experimental information on misorientation distribution and initial grain size were also performed, and the simulated Ni silicide grain morphology is in good agreement with the in-situ SEM results during agglomeration. In order to slow down or to suppress the agglomeration, it is highly recommended to increase the volume fraction of low angle grains, and/or to decrease the misorientation between the NiSi grain and the Si substrate or between the NiSi grains.

Ion beam modification of the Ni-Si solid-phase reaction: The influence of substrate damage and nitrogen impurities introduced by ion implantation

We report on the growth of thin NiSi films via the thermal reaction of Ni layers (13–35 nm) with Si(100) substrates modified by ion implantation. By introducing substrate damage or nitrogen impurities prior to the solid-phase reaction, several properties of the NiSi films can be modified: the formation temperature, texture, diffusion-limited growth rate and morphological stability. As some of the modifications to the NiSi films are rooted in the early silicide phases preceding the NiSi phase, particularly its formation temperature, special attention is devoted to the growth of the amorphous Ni-Si alloy and the crystalline δ-Ni2Si and θ-Ni2Si phases.We employed a number of experimental techniques, including in situ synchrotron x-ray diffraction (XRD), in situ Rutherford backscattering spectrometry (RBS), in situ sheet resistance measurements, ex situ ion beam channelling and ex situ pole figure measurements. We show that both the formation temperature of the NiSi films and the intensity of epitaxial and axiotaxial components of the NiSi texture can be either lowered or raised by selecting appropriate implantation conditions. Agglomeration of the NiSi films at high temperature (> 700 °C) can be slowed down, either by slowing down the mobility of the Ni and Si atoms, or by removing the morphologically destabilizing axiotaxial texture. Our results emphasize the strong interwoven nature of phase formation, texture and morphological degradation. We illustrate that the kinetics of the early stages of thin film reactions consist of more than just diffusion, i.e. nucleation can also play a crucial role.

Impurity-enhanced solid-state amorphization: the Ni–Si thin film reaction altered by nitrogen

Solid-state amorphization, the growth of an amorphous phase during annealing, has been studied in a wide variety of thin film structures. Whereas research on the remarkable growth of such a metastable phase has mostly focused on strictly binary systems, far less is known about the influence of impurities on such reactions. In this paper, the influence of nitrogen, introduced via ion implantation, is studied on the solid-state amorphization reaction of thin (35 nm) Ni films with Si, using in situ x-ray diffraction (XRD), ex situ Rutherford backscattering spectrometry, XTEM, and synchrotron XRD. It is shown that due to small amounts of nitrogen (<2 at.%), an amorphous Ni–Si phase grows almost an order of magnitude thicker during annealing than for unimplanted samples. Nitrogen hinders the nucleation of the first crystalline phases, leading to a new reaction path: the formation of the metal-rich crystalline silicides is suppressed in favour of an amorphous Ni–Si alloy; during a brief temperature window between 330 and 350 °C, the entire film is converted to an amorphous phase. The first crystalline structure to grow is the orthorhombic NiSi phase. We demonstrate that this impurity-enchanced solid-state amorphization reaction occurs only under specific implantation conditions. In particular, the initial distribution of nitrogen upon implantation is crucial: sufficient nitrogen impurities must be present at the interface throughout the reaction. Introducing implantation damage without nitrogen impurities (e.g. by implanting a noble gas) does not cause the enhanced solid-state amorphization reaction. Moreover, we show that the stabilizing effect of nitrogen on amorphous Ni–Si films (with a composition ranging from 40% to 50% Si) is not restricted to thin film reactions, but is a general feature of the Ni–Si system.

Lamellar-structured Ni-silicide film formed by eutectic solidification

Abstract Pt-doped NiSi‒NiSi2 thin films in a uniform lamellar structure with a periodicity on the scale of a few tens of nanometers were formed on Si(001) substrates using a continuous laser scanning process. When the Pt-doped NiSi film was melted at high temperatures and was supercooled at high solidification rates (a high scanning speed of over 200 mm/s), a NiSi‒NiSi2 lamellar structure evolved while interacting with the underlying Si substrate and following the classical eutectic solidification path. The lamellar spacing could be easily controlled by the laser scanning speed. In addition, the periodically formed, nearly single-crystalline NiSi and NiSi2 phases exhibited epitaxial relationships with each other and also with the Si(001) substrate. It is believed that this novel NiSi‒NiSi2 lamellar structure can be used as a template for application areas requiring an electrode with a line/space pattern on the scale of a few tens of nanometers that can be prepared without using costly photolithographic processes.

Retrieving overlapping crystals information from TEM nano-beam electron diffraction patterns.

The diffraction patterns acquired with a transmission electron microscope (TEM) contain Bragg reflections related to all the crystals superimposed in the thin foil and crossed by the electron beam. Regarding TEM-based orientation and phase characterisation techniques, the nondissociation of these signals is usually considered as the main limitation for the indexation of diffraction patterns. A new method to identify the information related to the distinct but overlapped grains is presented. It consists in subtracting the signature of the dominant crystal before reindexing the diffraction pattern. The method is coupled to the template matching algorithm used in a standard automated crystal orientation mapping tool (ACOM-TEM). The capabilities of the approach are illustrated with the characterisation of a NiSi thin film stacked on a monocrystalline Si layer. Then, a subtracting-indexing cycle applied to a 70 nm thick thin foil containing polycrystalline tungsten electrical contacts shows the capability of the technique to recognise small nondominant grains.

Enhanced thermoelectric property and stability of NiCr–NiSi thin film thermocouple on superalloy substrate

Thin film thermocouples (TFTCs) can provide fast and accurate surface temperature measurement with minimal impact on the physical characteristics of the supporting components. In this study, NiCr and NiSi films were prepared with radio frequency (RF) magnetron sputtering and the influences of vacuum annealing on the resistivity of the films were investigated. Afterward, NiCr–NiSi films were deposited on Ni-based superalloy substrates to form TFTCs. The overall dimension of the thermocouple is 64 mm in length, 8 mm in width and 30 μm in thickness. Compared with those of as-deposited sample, the thermoelectric property and stability of the TFTC are significantly improved by vacuum annealing of NiCr and NiSi films. The variation of the Seebeck coefficient of TFTC was discussed based on the size effect of NiCr and NiSi films. And a lower Seebeck coefficient of TFTC of 38.4 μV·°C−1 is obtained.

Phase analysis and thermal stability of thin films synthesized via solid state reaction of Ni with Si1 − xGex substrate

The products of the solid state reaction involving ultra-thin Ni film (6nm) and Si1−xGex layers (Ge 25 and 55at.%), were analysed using sheet resistance (Rs), glancing angle X-ray diffraction (GIXRD), scanning electron and atomic force microscopy (SEM, AFM) techniques. The reaction was carried out via rapid thermal process (RTP) annealing using two different steps (RTP1 and RTP2) while applying a selective etch (SE) in between them. The intermediate and the end reaction products resulting after RTP1 and RTP2 were found to be dependent on the Ge content, forming Ni-rich silicide (Ni2Si) and NiSi on Si75Ge25, while Ni-rich germanide (Ni5Ge3) and NiGe were obtained by using Si45Ge55. Though the onset of intermediate Ni-rich silicide or germanide phase formation occurs at similar RTP1 temperature (275°C), the reaction completion to yield low resistive phase NiSi or NiGe phase results at different RTP2 temperatures (400°C vs 350°C). Based on the volume expansion, a resistivity value of 25μΩcm was obtained for the synthesized NiGe (12nm) and NiSi (14nm) layers. Independent of the phases obtained, the films were found to be closed and homogeneous and exhibit rms roughness of 0.5–0.8nm as evidenced by SEM and AFM analysis. Thermal stability studies carried out on NiSi and NiGe thin films, post RTP1/RTP2, show the latter phase to have limited stability and result in Rs degradation starting already at 475°C due to phase decomposition.

NixSi1-x Alloy Negative Electrodes for Li-Ion Batteries

Introduction Si containing alloys are promising candidates as anode materials for lithium ion batteries. This is owing to the high theoretical capacity of Si (2194 Ah/L, compared to 764 Ah/L for graphite) [1]. Pure Si, however, suffers from severe volume expansion (280% in the fully lithiated state) during the lithiation/delithiation process [2]. High internal stress in the electrode can lead to particle cracking, poor electrical contact and thus poor cycling stability. The use of active/inactive composites is an efficient way to reduce volume expansion and improve cycling performance [1,3]. In the present study, NixSi1-x (0≤x≤0.65) thin film libraries were synthesized by combinatorial sputtering. A structural and compositional analysis of the films and the effect of composition on their electrochemical behavior are presented. It was found that the capacity of NixSi1-x thin films could not be explained by the lithiation mechanisms proposed in any of the previous studies of Si-TM films. Instead, it was found that increasing Ni content suppressed the average lithiation voltage, resulting in capacity reduction, however all the Si in the alloy remained active. Experimental Thin film libraries of Ni-Si were fabricated using sputtering. Cu foil discs with sputtered thin films were assembled in 2325-type coin cells with Li metal foil (99.9%, Sigma-Aldrich) counter electrodes. 1M LiPF6 (BASF) in a solution of ethylene carbonate, diethyl carbonate and monofluoroethylene carbonate (volume ratio 3:6:1, all from Novolyte Technologies) was used as electrolyte. Cells were galvanostatically cycled at 30.0 ± 0.1 °C between 5 mV and 0.9 V with a Maccor Series 4000 Automated Test System. Results Selected XRD patterns of two Ni-Si thin films are shown in Figure 1. All the patterns have two broad diffraction peaks at around 28° and 49°, indicating the amorphous nature of sputtered thin films. With the increase of Ni content, the intensity of the peak at 49° increases and its position shifts slightly to lower angle. Figure 2 shows the differential capacity curves of the same Ni-Si thin films shown in Figure 1. Two broad peaks during lithiation (denoted as peak A and B) and two corresponding peaks during delithiation (denoted as peak A' and B') can be clearly observed for the Ni0.04Si0.96 thin film. The two lithiation peaks shift to less positive voltages for Ni0.35Si0.65 thin film while the B' peak position remains unchanged. The apparent suppression in discharge voltage by increasing Ni content causes a reduction in the film capacity. This would suggest that some of the Si is becoming inactive, but this is not the case. While peak B becomes truncated by the voltage suppression the capacity of peaks A/A' remain unaffected and therefore can be used as a measure of active Si in the alloy. Figure 3 shows the percent active Si present in the Ni-Si films calculated on the basis of the capacity under peak A'. According to this model all Si atoms are active to Li. Above x = 0.4 the amount of active Si decreases only because peak A also becomes truncated for these compositions. The model reported by Fleischauer et al. [4] does not explain the behavior observed here and is also shown in Figure 3 for comparison. Here the electrochemistry of Ni-Si films will be discussed. It will be suggested the lithiation voltage suppression observed in these films arises from internal stress that arises between the expanding Si active phase and the inactive Ni phase. This has important consequences for other Si/inactive alloy negative electrodes.

A Nanoarchitectured Porous Electrode Assembly of NiSi Thin Film for Lithium Ion Batteries

This study proposes to produce well-aligned nanorod arrays containing NiSi thin film to improve the electrochemical performance of Si based anodes. In this respect, NiSi thin films made of nanorods are produced via glancing angle electron beam deposition (GLAD) technique. The structural and morphological properties are investigated using thin film X-ray diffraction (XRD) and scanning electron microscopy (SEM). The well aligned nanorod arrays containing NiSi thin film anode exhibits a long cycle life with a moderate capacity retention (around 1100mAhg-1 for 100 cycles). This remarkable electrochemical performance can be explained by the electrode composition, structure and morphology: During Li+ insertion into the alloyed thin film electrodes, Si acts as active center, which reacts with Li+ to form amorphous LixSi alloys, while the nanosized Ni particles are believed to provide electrical conduction network inside the active material and buffer volume expansions with the help of the homogenously distributed nanosized interspaces (porosities among the nanorods) present in the thin film.

FILM THICKNESS INFLUENCES ON THE THERMOELECTRIC PROPERTIES OF NiCr/NiSi THIN FILM THERMOCOUPLES

NiCr / NiSi thin film thermocouples (TFTCs) with a multi-layer structure were fabricated on Ni -based superalloy substrates (95 mm × 35 mm × 2 mm) by magnetron sputtering and electron beam evaporation. The five-layer structure is composed of NiCrAlY buffer layer (2 μm), thermally grown Al 2 O 3 bond layer (200 nm), Al 2 O 3 insulating layer (10 μm), NiCr / NiSi TFTCs (1 μm), and Al 2 O 3 protective layer (500 nm). Influences of thermocouple layer thickness on thermoelectric properties were investigated. Seebeck coefficient of the samples with the increase in thermocouple layer thickness from 0.5 μm to 1 μm increased from 27.8 μV/°C to 33.8 μV/°C, but exhibited almost no change with further increase in thermocouple layer thickness from 1 μm to 2 μm. Dependence on temperature of the thermal electromotive force of the samples almost followed standard thermocouple characteristic curves when the thickness of the thermocouple layer was 1 μm and 2 μm. Sensitive coefficient K of the samples increased greatly with the increase in thickness of the thermocouple layer from 0.5 μm to 1 μm, but decreased insignificantly with the increase in thermocouple layer thickness from 1 μm to 2 μm, and continuously decreased with the increase in temperature. The sensitive coefficient and the stability of NiCr / NiSi TFTCs were both improved after annealing at 600°C.

Thermal stability of Ni(Ta) silicide films on ultra-thin silicon-on-insulator substrates

This study first investigated the thermal stability of Ni(Ta) silicides on ultra-thin silicon-on-insulator (SOI) substrates. The presence of Ta atoms significantly decreased the resistivity of Ni(Ta)Si thin films. Compared to the Ni/Si system, the Ni(Ta)Si films formed on ultra-thin SOI were found to exhibit remarkably improved morphological stability. For the Ni(Ta)/SOI samples, the process window of low-resistivity Ni(Ta)Si silicides was extended to high temperature up to 850°C. This study explained these phenomena in terms of the thermally robust Ni(Ta)Si/SiO2 interface and Ta-accumulated grain boundaries in the Ni(Ta)Si films. Ta-accumulated grain boundaries may act as adhesive in Ni(Ta)Si films, effectively hindering the agglomeration of Ni(Ta)Si films and thus extending the low-resistivity process window of Ni(Ta)Si silicides. This work demonstrated the potential of Ni(Ta) silicidation on ultra-thin SOI substrates for device applications.

NiSi crystal structure, site preference, and partitioning behavior of palladium in NiSi(Pd)/Si(100) thin films: Experiments and calculations

The crystal structure of a NiSi thin-film on a Si substrate and Pd site-substitution in NiSi and the partitioning behavior of Pd for NiSi(Pd)/Si(100) are investigated by x-ray diffraction (XRD), first-principles calculations, and atom-probe tomography (APT). The NiSi layer is a distorted orthorhombic structure from XRD patterns via experiments and calculations. We find that Pd has a strong driving force, 0.72 eV atom−1, for partitioning from Si into the orthorhombic NiSi layer. The calculated substitutional energies of Pd in NiSi indicate that Pd has a strong preference for Ni sublattice-sites, which is in agreement with concentration profiles determined by APT.

Ni silicide formation on epitaxial Si 1 − yC y/(001) layers

The formation of Ni silicides on Si 1 − y C y ( y = 0.01 and 0.018) epilayers grown on Si(001) has been investigated. The presence of C atoms was found to significantly retard the growth kinetics of NiSi and enhances the thermal stability of thin NiSi films. For Ni(11 nm)/Si 0.982C 0.018 samples, the process window of NiSi was shifted and extended to 450–700 °C. Moreover, there was an additional strain introduced into the Si 1 − y C y epilayers during Ni silicidation. This work shows the potential of Ni silicidation on Si 1 y C y for device applications.

Optical metrology of Ni and NiSi thin films used in the self-aligned silicidation process

The thickness-dependent optical properties of nickel metal and nickel monosilicide (NiSi) thin films, used for self-aligned silicidation process, were characterized using spectroscopic ellipsometry. The thickness-dependent complex dielectric function of nickel metal films is shown to be correlated with the change in Drude free electron relaxation time. The change in relaxation time can be traced to the change in grain boundary (GB) reflection coefficient and grain size. A resistivity based model was used as the complementary method to the thickness-dependent optical model to trace the change in GB reflection coefficient and grain size. After silicidation, the complex dielectric function of NiSi films exhibit non-Drude behavior due to superimposition of interband absorptions arising at lower frequencies. The Optical models of the complete film stack were refined using x-ray photoelectron spectroscopy, Rutherford backscattered spectroscopy, and x-ray reflectivity (XRR).

Leakage Reduction by Thermal Annealing of NiPtSi Silicided Junctions and Anomalous Grain-Incompatible Pt Network

Using highly reliable damage-free junctions, the effectiveness and limitation of Pt addition for the stabilization of thin NiSi films are accurately specified and practically formulated in terms of the thermally induced leakage. In addition to the thermal leakage, the unexpected emergence of initial leakage is also witnessed and attributed to the emission of Si interstitials during silicidation and the subsequent formation of boron interstitial clusters. Rapid evanescence of the initial leakage by post-annealing is also successfully demonstrated owing to the Pt-induced thermal stabilization. Moreover, unlike other Pt distributions considered so far, Pt atoms are revealed to concentrate in a distinctive manner, forming an anomalous in-layer web-like structure which even extends within single NiSi grains. This grain-incompatible Pt network is thought to be a remnant of Pt-aggregation around grain boundaries of an earlier metal-rich silicide phase (e.g., Ni2Si), incorporated and left intact in the final phase (i.e., NiSi). Such intermediate-phase Pt-rearrangement may have interfered with the phase transition sequence and reoriented the final NiSi grains to constitute a crystallographically stable and thermally robust interface structure, resulting in the effective stabilization by Pt addition.