Effect of Nitrogen and Oxygen Impurities on Tantalum Silicide Formation

ABSTRACTTantalum, being a refractory metal, is sensitive to ambient impurities when forming a silicide. By introducing nitrogen and oxygen impurities into a tantalum-silicon system, interesting chemical and physical effects are observed in their subsequent reactions. Nitrogen and oxygen behave similarly in such a system. If initially present in Ta, they segregate into the still unreacted Ta as the silicide layer grows at a somewhat retarded rate. The same impurities, initially present in Si, are immobile in the form of stable compouis and suppress TaSi2 growth. The rare isotopes 15N and 18O are introduced bY implantation and Profiled by 15N(P,α)12C and 18O(P,α)15N nuclear reaction analyses, respectively. In addition, unintentionally incorporated 18O is checked by the 16O(d,α) 14N nuclear reaction. The results are explained in terms of the moving species Si, and of the chemical affinity, solubility and diffusivity of the impurities in their host lattice.

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Influence of Nitrogen Impurities on Nickel and Platinum Silicide Formation

MRS Proceedings ◽

10.1557/proc-18-243 ◽

1982 ◽

Vol 18 ◽

Author(s):

K. T. Ho ◽

M.-A. Nicolet ◽

L. WieluŃSki

Keyword(s):

Stable Isotope ◽

Nuclear Reaction ◽

Silicon Substrate ◽

Metal Films ◽

Silicon Substrates ◽

Chemical Affinity ◽

Silicide Formation ◽

Platinum Silicide ◽

Model Based ◽

Thin Nickel

In the present study we investigate the influence of nitrogen on the silicide formation of thin nickel and platinum films. Nitrogen is introduced by implantation either in the metal films or in the silicon substrates. We use the rare stable isotope 15N for the implantation and the nuclear reaction 15N(p,α)12C for the detection and profiling of the impurity. For nitrogen in nickel, we find that at 350 °C nitrogen is mobile. It accumulates at the bottom nickel interface and, for a dose exceeding about 0.5 × 1016 N atoms cm−2, forms a barrier to silicide formation. When nitrogen is initially in the silicon substrate, the nitrogen profile is broadened in the same proportion as the dilution of the silicon sublattice when forming the silicide. Similar experiments with platinum films showed partially different behaviors. All results are explained in terms of a model based on the moving species during the silicide formation and the chemical affinity of nitrogen to the metal and to silicon.

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Palladium silicide formation under the influence of nitrogen and oxygen impurities

Journal of Applied Physics ◽

10.1063/1.334794 ◽

1985 ◽

Vol 57 (2) ◽

pp. 232-236 ◽

Cited By ~ 13

Author(s):

K. T. Ho ◽

C.‐D. Lien ◽

M‐A. Nicolet

Keyword(s):

Silicide Formation ◽

Palladium Silicide ◽

Oxygen Impurities

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Co2Si, CrSi2, ZrSi2 and TiSi2 Formation Studied by a Radioactive 31Si Marker Technique

MRS Proceedings ◽

10.1557/proc-10-129 ◽

1981 ◽

Vol 10 ◽

Cited By ~ 4

Author(s):

A. P. Botha ◽

R. Pretorius

Keyword(s):

Diffusion Coefficient ◽

Half Life ◽

Vacancy Diffusion ◽

Silicide Formation ◽

Activity Profile ◽

Initial Layer ◽

Self Diffusion ◽

Silicide Layer ◽

Self Diffusion Coefficient

Radioactive 31Si (half-life, 2.62 h) was used as a marker to study Co2Si, CrSi2, TiSi2 and ZrSi2 formation. By marking the initial layer of silicide with radioactive silicon atoms and by measuring the activity profile in the silicide layer after further silicide formation, the dominant diffusing species and its mechanism of diffusion during the formation of these silicides could be determined. For Co2Si it was found that cobalt is the diffusing species, while disilicide formation was found to take place by silicon substitutional (vacancy) diffusion, with a high self-diffusion coefficient.

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Characteristics of Selective Lpcvd W Films By Silicon Reduction

MRS Proceedings ◽

10.1557/proc-71-309 ◽

1986 ◽

Vol 71 ◽

Cited By ~ 1

Author(s):

R. V. Joshi ◽

D. A. Smith

Keyword(s):

Crystal Structure ◽

Grain Size ◽

Annealing Temperature ◽

Film Surface ◽

Silicide Formation ◽

X Ray ◽

Tungsten Hexafluoride ◽

Deposited Film ◽

Deposited Films ◽

Oxygen Impurities

AbstractThe characteristics of Selective LPCVD tungsten films produced by silicon reduction of tungsten hexafluoride are presented. The tungsten films deposited using Si(100), Si(111) and polysilicon undoped and doped substrates are analyzed by X-RAY, TEM, RBS, AES, SIMS and SEM. The as deposited bcc tungsten films are polycrystalline with a grain size 80 - 100Å. The effect of annealing temperature and time on the crystal structure of films was studied. Tungsten reacts to form tungsten silicide at 600°C. The silicide grain size is of the order of 100 - 200Å at 600°C and increases gradually to 400 - 500Å at 1000°C. The oxygen impurities in the film retard the silicide formation further at 1000°C. Silicon from the substrate out-diffuses to the film surface and reacts with the presence of oxygen impurities in the annealing ambient to form Si-O at 1000°C. As deposited film resistivities of 130-140 micro-ohm-cm are achieved reproducibly and reach 60-70 micro-ohm-cm after 1000°C annealing in nitrogen or argon ambient. The impurities H, C, O and F are found in the as deposited films.

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Silicide Formation at HfO2/Si and ZrO2/Si Interfaces Induced by Ar+ Ion Bombardment

MRS Proceedings ◽

10.1557/proc-786-e3.25 ◽

2003 ◽

Vol 786 ◽

Author(s):

Yu. Lebedinskii ◽

A. Zenkevich ◽

D. Filatov ◽

D. Antonov ◽

J. Gushina ◽

...

Keyword(s):

Metal Oxide ◽

Ion Beam ◽

Ion Bombardment ◽

Ex Situ ◽

Silicide Formation ◽

Ion Etching ◽

Silicide Layer ◽

Layer 2 ◽

Silicon Interface

ABSTRACTThe effect of ion bombardment with Ar+ at the energy E=2.5 keV on HfO2/Si and ZrO2/Si interfaces has been investigated in situ with XPS by growing thin metal oxide layers and further ion etching them. It is shown that a silicide layer ∼2 nm in thickness is forming, and Ar+ ion beam affects MeO2/Si (Me=Hf, Zr) interface at thickness ≤3 nm. Ex situ AFM/STM corroborates the formation of silicide layer at metal oxide/silicon interface.

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Marker Experiments for the moving Species in Silicides During Solid Phase Epitaxy of Evaporated Si

MRS Proceedings ◽

10.1557/proc-25-51 ◽

1983 ◽

Vol 25 ◽

Cited By ~ 26

Author(s):

Chuen-Der Lien ◽

Meir Bartur ◽

Marc-A. Nicolet

Keyword(s):

Nuclear Reaction ◽

Solid Phase ◽

Solid Phase Epitaxy ◽

Silicide Formation ◽

Si Substrate ◽

Marker Position

ABSTRACTEvaporated W, implanted Xe, and implanted 18O were used as markers to study the dominant moving species during (a) solid phase epitaxy (SPE) of evaporated Si, (b) silicide formation, and (c) oxidation of silicides on Si substrate.MeV 4He+ backscattering spectrometry and 18O (p, α)15 N nuclear reaction were used to monitor the evolution of elemental profiles as well as the change in the marker position. In most cases, the dominant moving species in SPE is the same as that observed in the formation and oxidation of that silicide. However, in CrSi2 the dominant moving species is Si during silicide formation, but Cr during SPE or oxidation.

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Rhodium and silicon system: II. Rhodium silicide formation

Nanotechnology ◽

10.1088/0957-4484/21/36/365707 ◽

2010 ◽

Vol 21 (36) ◽

pp. 365707 ◽

Cited By ~ 13

Author(s):

L Marot ◽

R Schoch ◽

R Steiner ◽

V Thommen ◽

D Mathys ◽

...

Keyword(s):

Silicide Formation ◽

Silicon System

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In situ Transmission Electron Microscope observations of mesotaxial silicide formation in the CoSi2/Si system

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154238 ◽

1989 ◽

Vol 47 ◽

pp. 452-453

Author(s):

R. Hull ◽

A.E. White ◽

K.T. Short ◽

S.M. Yalisove ◽

D. Loretto

Keyword(s):

Electron Microscope ◽

Transmission Electron Microscope ◽

Ex Situ ◽

Metal Silicide ◽

Silicide Formation ◽

Plan View ◽

Silicide Layer ◽

Transmission Electron ◽

In Situ Experiments

A new technique for synthesis of buried epitaxial metal silicide layers in Si (“mesotaxy”) by high-dose implantation of Co and Ni into Si surfaces has been developed. Subsequent to implantation at energies in the few hundred keV range and doses in the 1017Cm−2 regime, thermal annealing at temperatures up to 1000°C results in the formation of well-defined and relatively high quality Si/metal disilicide/Si structures.The exact implantation and processing conditions are crucial in determining the structure and quality of the buried silicide layer. In this work, we describe transmission electron microscope experiments which illuminate the silicide formation process both by static studies of as-implanted and annealed structures, and dynamical in-situ experiments where as-implanted structures are annealed inside the microscope to mimic the ex-situ annealing conditions. The structure geometry in these materials turns out to be close to ideal for such in-situ experimentation: typical implantation conditions for formation of a contiguous silicide layer result in tlqe metal layers being of the order a few hundred to a thousand Å and buried about 600-1000 Å below the Si surface. In-situ annealing in the plan-view geometry inhibits surface diffusion across the interfaces, which would be expected in the cross-sectional geometry (5). The typical penetration depths attainable in Si with 200 keV electrons, say ~ 1 micron, allow a significant thickness, hsubthin of Si substrate below the metal layer, thickness hm, to be retained during the in-situ experiment such that hm ≪hsubthin. This is important, as it ensures that the film stress condition (which arises because of the difference in bulk lattice parameters between the Si and metal silicide layers) is reasonably representative of the stress conditions relevant for the case of annealing on the unthinned substrate.

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