Growth of near noble metal Pd and Pt thin film silicides morphology and structure

Author(s):  
E. I. Alessandrini ◽  
M. O. Aboelfotoh

Considerable interest has been generated in solid state reactions between thin films of near noble metals and silicon. These metals deposited on Si form numerous stable chemical compounds at low temperatures and have found applications as Schottky barrier contacts to silicon in VLSI devices. Since the very first phase that nucleates in contact with Si determines the barrier properties, the purpose of our study was to investigate the silicide formation of the near noble metals, Pd and Pt, at very thin thickness of the metal films on amorphous silicon.Films of Pd and Pt in the thickness range of 0.5nm to 20nm were made by room temperature evaporation on 40nm thick amorphous Si films, which were first deposited on 30nm thick amorphous Si3N4 membranes in a window configuration. The deposition rate was 0.1 to 0.5nm/sec and the pressure during deposition was 3 x 10 -7 Torr. The samples were annealed at temperatures in the range from 200° to 650°C in a furnace with helium purified by hot (950°C) Ti particles. Transmission electron microscopy and diffraction techniques were used to evaluate changes in structure and morphology of the phases formed as a function of metal thickness and annealing temperature.

1982 ◽  
Vol 18 ◽  
Author(s):  
L. Krusin-Elbaum ◽  
M. Wittmer ◽  
C.-Y. Ting ◽  
J. J. Cuomo

We have studied reactively sputtered ZrN, the most thermally stable of the refractory metal nitrides, for its diffusion barrier properties in aluminum metallization schemes with Rutherford backscattering spectroscopy and transmission electron microscopy (TEM). We find this compound to be very effective against aluminum diffusion up to 500 °C, independently of substrate temperature during sputtering. The useful temperature range can be extended by 50 °C with proper preannealing prior to aluminum deposition. The TEM study of the ZrN grain size as a function of annealing temperature revealed that the grain size does not change significantly upon annealing and that the grains are relatively small even at the highest annealing temperatures (about 300 Å at 900 °C). In addition, for annealing temperatures of and below 500 °C large portions of ZrN films were found to be of either amorphous or extremely fine–grain material, thus inhibiting the diffusion along grain boundaries. The presence of Zr3Al4Si5 ternary compound in samples annealed at 600 °C, as determined by X-ray analysis, may suggest that the ZrN barrier fails by decomposition of the film by aluminum.


1992 ◽  
Vol 259 ◽  
Author(s):  
T. George ◽  
R. P. Vasquez ◽  
S. S. Kim ◽  
R.W. Fathauer ◽  
W. T. Pike

ABSTRACTThe nature of light-emitting porous Si layers produced by non-anodic stain etching of p-type (100) Si substrates is studied. The layers were characterized by transmission electron microscopy as being amorphous in nature. X-ray photoelectron spectroscopy and electron spin resonance measurements show these layers to be composed mainly of a-Si. The formation mechanism of the a-Si is explored using by stain etching SiGe ‘marker’ layers within epitaxially grown Si films and by high temperature annealing. These experiments provide strong evidence for a spontaneous crystalline-amorphous phase transformation during the etching process.


1986 ◽  
Vol 74 ◽  
Author(s):  
R. Kwor ◽  
S. M. Tang ◽  
N. S. Alvi

AbstractThe effect of rapid thermal annealing on the crystallization of arsenic and boron implanted amorphous silicon films is studied. Amorphous Si films of 4000 Å were deposited using LPCVD and implanted with arsenic or boron to doses of 5 × 1013, 5 × 1014, and 5 × 1015 cm−2. These films were then annealed using an Eaton Nova-400 RTA system (with temperature ranging from 900 to 1200 °C and dwell time ranging from 1 to 30 sec). The annealed films were studied using transmission electron microscopy, Hall effect measurement and temperature coefficient of resistance measurement. The optimal annealing conditions for the films were found.


2004 ◽  
Vol 841 ◽  
Author(s):  
J. S. Williams ◽  
B. Haberl ◽  
J. E. Bradby

ABSTRACTThe deformation behavior of both ion-implanted and deposited amorphous Si (a-Si) films has been studied using spherical nanoindentation, followed by analysis using Raman spectroscopy and cross-sectional transmission electron microscopy (XTEM). Indentation was carried out on both unannealed a-Si films (the so-called unrelaxed state) and in ion implanted films that were annealed to 450°C to fully relax the amorphous film. The dominant mode of deformation in unrelaxed films was via plastic flow of the amorphous phase rather than phase transformation, with measured hardness being typically 75–85% of that of crystalline Si. In contrast, deformation via phase transformation was clearly observed in the relaxed state of ion implanted a-Si, with the load-unload curves displaying characteristic discontinuities and Raman and XTEM indicating the presence of high-pressure crystalline phases Si-III and Si-XII following pressure release. In such cases the measured hardness was within 5% of that of the crystalline phase.


1990 ◽  
Vol 187 ◽  
Author(s):  
James S. Im ◽  
Harry A. Atwater

AbstractThe nucleation and transformation kinetics of the amorphous-to-crystal transition in Si films under 1.5 MeV Xe+ irradiation have been investigated by means of in situ transmission electron microscopy in the temperature range T = 480–580°C. After an incubation period during which negligible nucleation occurs, a constant nucleation rate was observed in steady state, suggesting homogeneous nucleation. A significant enhancement in nucleation rate during high energy ion irradiation (6 orders of magnitude) was observed as compared with thermal crystallization, with an apparent activation energy of Qn = 3.9 ± 0.75 eV. Independent analyses of the temperature dependence of the incubation time, the crystal growth rate, and nucleation rate suggest that interface rearrangement kinetics and not the thermodynamic barrier to crystallization, are affected by ion irradiation.


1991 ◽  
Vol 230 ◽  
Author(s):  
Tomonori Yamaoka ◽  
Keiji Oyoshi ◽  
Takashi Tagami ◽  
Yasunori Arima ◽  
Shuhei Tanaka

AbstractCrystallization of amorphous Si films on a glass substrate using Si+ ion implantation is investigated. 100keV and 180keV Si+ ion implantations into 600nm-thick amorphous Si layers crystallize half and almost all of the film thicknesses, respectively. This result demonstrates that crystallization by ion implantation, which contains both crystal nucleation and grain growth, is due to ion-solid interaction, and not to “pure” thermal effect by ion beam heating. Furthermore, two distinct regions are observed in transmission electron microscopy investigation of grain size at different depths of crystallized Si/SiO2 multi-layer specimens. The deep region below the projected range is composed of grains smaller than in the shallow region. This result is strongly related with crystal nucleation and growth kinetics by ion implantation.


1983 ◽  
Vol 25 ◽  
Author(s):  
H. Yamamoto ◽  
H. Ishiwara ◽  
S. Furukawa ◽  
M. Tamura ◽  
T. Tokuyama

ABSTRACTLateral solid phase epitaxy (L-SPE) of amorphous Si (a-Si) films vacuum-evaporated on Si substrates with SiO2 patterns has been investigated, in which the film first grows vertically in the regions directly contacted to the Si substrates and then grows laterally onto SiO2 patterns. It has been found from transmission electron microscopy and Nomarski optical microscopy that use of dense a-Si films, which are formed by evaporation on heated substrates and subsequent amorphization by Si+ ion implantation, is essentially important for L-SPE. The maximum L-SPE length of 5–6μm was obtained along the <010> direction after 10hourannealing at 600°C. The kinetics of the L-SPE growth has also been investigated.


1992 ◽  
Vol 70 (10-11) ◽  
pp. 1184-1193 ◽  
Author(s):  
D. J. Lockwood ◽  
G. C. Aers ◽  
L. B. Allard ◽  
B. Bryskiewicz ◽  
S. Charbonneau ◽  
...  

The optical and structural properties of porous Si films produced by electrochemical and chemical dissolution of Si have been studied by a variety of techniques. Raman scattering and transmission electron microscopy have shown the samples to contain crystalline Si wires and (or) spherites 3–8 nm in diameter and (or) amorphous Si. The optical absorption spectra and the wavelength, temperature, and lifetime dependence of the photoluminescence obtained from most of the samples are entirely consistent with the quantum confinement of excitons in Si nanostructures. Quite different photoluminescence was obtained from other samples composed only of amorphous Si, and this is attributed to the presence of silicon oxyhydride species.


1992 ◽  
Vol 70 (10-11) ◽  
pp. 860-865 ◽  
Author(s):  
Douglas G. Ivey ◽  
Dashan Wang

The formation of FeSi2, as well as other iron silicides, from solid-state reactions of Fe thin films on Si substrates has been investigated. Iron layers, approximately 50 nm thick, were deposited by electron beam evaporation on <100> oriented Si substrates. Silicon (≈35 nm) and SiO2 (≈170 nm) layers were deposited on top of the Fe layer in the same evaporator without breaking the chamber vacuum. SiO2 acted as a protective layer during subsequent annealing in a nitrogen ambient. All annealed samples were examined using X-ray diffraction and transmission electron microscopy (TEM). Both plan view and cross section specimens were prepared for TEM. Detailed phase analysis was accomplished through the various electron diffraction and X-ray microanalysis techniques available with the TEM. Silicon dissolved readily in Fe, at temperatures lower than 300 °C, up to the solubility limit of ≈26 at%Si. FeSi formation followed (350 °C), with semiconducting FeSi2 forming at 500 °C. The Fe–amorphous Si interface was more reactive, with silicide formation occurring at lower annealing temperatures (300 °C). There was also evidence that FeSi2 formed directly from α-Fe and amorphous Si.


1994 ◽  
Vol 336 ◽  
Author(s):  
J. R. A. Carlsson ◽  
C. Bandmann ◽  
S. Csillag ◽  
X.-H. Li ◽  
M. Johansson

ABSTRACTIn order to study the dependence of the atomic fine structure and optical band gap of the amorphous alloy on concentration and annealing temperature, thin Si1−XBX alloy films were grown and then annealed at temperatures from 400 to 1050 °C. The films were characterized by Extended Energy Loss Fine Structure spectroscopy (EXELFS), High Resolution transmission Electron Microscopy (HREM), Auger Electron Spectroscopy (AES), and light absorption spectro-photometry. It is shown that all the amorphous Si1−XBX alloys are thermally stable (e.g., >1050 °C for x=0.6) as compared to a-Si, and that the optical band gap of the alloys increases gradually with annealing temperatures up to 700 – 900 °C. When annealed at higher temperatures the band gap increased rapidly, corresponding to a phase transformation between two amorphous phases.


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