Rapid Thermal Annealing In Nitrogen Research Articles

Role of silver nanoparticles in the dewetting behavior of copper thin films

We report on the effect of added silver on the solid state dewetting behavior of copper thin films, grown by thermal evaporation. The films were annealed under different conditions, conventional furnace annealing in air and argon and rapid thermal annealing in nitrogen. Our results show that for all annealing conditions, addition of silver to copper films suppresses the dewetting when compared to pure copper films. Fully dewet silver–copper films produce roughly spherical nanoparticles, with the amount of silver controlling the particle areal density and size distribution. This provides an additional parameter for controlled synthesis of nanoparticles by a bottom–up approach.

Effects of nitrogen doping of ZnO during or after deposition

Effects of nitrogen doping of ZnO (ZnO:N) during deposition and after postdeposition annealing have been studied by optical techniques, electronic properties, and the application to metal-semiconductor-metal photodetectors (MSM-PDs). Films of ZnO, nitrogen doped during rf sputtering, show larger grain size, narrower full width at half maximum, band gap emission shift in photoluminescence, and higher conductivity. Postannealing has been studied using tube furnace and rapid thermal annealing in nitrogen. These annealing methods not only reconstruct the lattice structure but also activate the nitrogen in the film to improve the conductivity of the film. The MSM-PDs having high photo to dark current ratio of 104 and responsive (R) of 1.79 A/W have been fabricated with those films.

Process development and material characterization of polycrystalline Bi2Te3, PbTe, and PbSnSeTe thin films on silicon for millimeter-scale thermoelectric generators

In this work, deposition, patterning, and metallization of vapor-deposited polycrystalline thermoelectric (TE) thin films of Bi2Te3, PbTe, and PbSnSeTe on silicon (Si) substrates are investigated. These fundamental microfabrication methods are intended for use in integrating TE films into thermally powered micro-electro-mechanical systems (MEMS)-based power generators. P-type polycrystalline Bi2Te3, PbTe, and PbSnSeTe films were successfully deposited on thermally oxidized (100) Si substrates to thicknesses ranging from 0.4 to 9 μm. Dry etch rates of about 0.6−0.7 μm/min were achieved for Bi2Te3 and PbTe/PbSnSeTe using methane-based gases. Wet etch rates of ∼3 μm/min were achieved using various acid wet chemistries. Films were electrically characterized using van der Pauw and transfer length method (TLM) test structures. Postdeposition resistivities were measured as low as 23 mΩ cm for Bi2Te3, 134 mΩ cm for PbTe, and 52 mΩ cm for PbSnSeTe. The Seebeck coefficients were measured at up to 94 μV/K for undoped Bi2Te3, and 160 and 42 μV/K for doped PbTe and PbSnSeTe, respectively. Metal contact resistivities (0.18−42 mΩ cm2) were also extracted for a variety of thin film metals (Pt, Au, Cu, Ni, Cr/Pt/Au, Ti/Pt). Various postdeposition annealing treatments were explored for reducing film resistivity that would enable higher power delivery for TE generator applications. Rapid thermal annealing in nitrogen at 400 °C was shown to reduce the resistivity of PbTe and improve film adhesion to oxidized silicon substrates. Also, after successive heatings in air at 200 °C, the resistivity of the PbTe films remained stable while that of the PbSnSeTe increased up to 10×.

Specific features of steady-state implantation of crystalline silicon with a molecular oxygen-nitrogen beam: Si L 2, 3 x-ray emission spectra

The local electronic structure of 〈111〉 n-silicon single-crystal samples is studied using Si L2, 3 x-ray emission spectroscopy. The SixOyNz system is formed by implanting the samples with an 16O2+ and 14N2+ ion molecular beam (the oxygen/nitrogen ratio in the molecular beam is 1:1, the implantation energy is 30 keV, the irradiation fluences vary from 2.0 × 1017 to 1.5 × 1018 cm−2, the samples after the implantation are subjected to rapid thermal annealing in nitrogen at 800°C for 5 min). A comparison of the recorded Si L spectra with the spectra of the reference samples reveals clear correlations between the specific features of the electronic structure of the silicon oxynitride formed upon implantation and the ion fluence. It is shown that the implantation at fluences of 2 × 1017 and 1 × 1018 cm−2 results in the predominant formation of Si3N4, whereas the implantation at a fluence of 1.5 × 1018 cm−2 leads primarily to the formation of SiO2 layers in single-crystal silicon. The most probable factors and mechanisms accounting for such implantation of 16O2+ and 14N2+ into the samples under study are discussed. The experimental data obtained are compared with ab initio full-potential linearized augmented plane wave calculations of the band structure.

Thermal stability of CdZnO∕ZnO multi-quantum-wells

The thermal stability of CdZnO∕ZnO multi-quantum-well (MQW) structures was studied using rapid thermal annealing in nitrogen from 300to750°C. Photoluminescence (PL) emission from the MQWs was studied while varying the annealing temperature and time. For 15min annealings, the PL center wavelength showed a 7nm reduction for temperatures up to 650°C. Above 650°C, the wavelength changed rapidly, with a 50nm reduction at 750°C. Annealing at 700°C for up to 20min produced a systematic reduction in PL wavelength up to 39nm. The data suggest that CdZnO∕ZnO MQWs are relatively stable for nitrogen annealing below 650°C for times up to 15min.

XPS Study of the Thermal Instability of HfO2 Prepared by Hf Sputtering in Oxygen with RTA

Hafnium oxide gate dielectric film was prepared by Hf sputtering in oxygen, and the thermal instability of was investigated by rapid thermal annealing (RTA) in nitrogen. X-ray photoelectron spectroscopy study reveals that the film is thermally unstable at postmetallization annealing temperatures The film decomposes and some oxygen atoms are released upon the RTA in nitrogen. In addition, the current-voltage characteristics of the capacitor are also highly unstable at temperatures higher than 300 K. These observations suggest that although has a much higher dielectric constant, it may not be suitable for the gate dielectric application because the postdeposition thermal treatment deteriorates both the physical and the electrical properties of the film. © 2003 The Electrochemical Society. All rights reserved.

Si (100)– SiO 2 interface properties following rapid thermal processing

An experimental examination of the properties of the Si(100)–SiO2 interface measured following rapid thermal processing (RTP) is presented. The interface properties have been examined using high frequency and quasi-static capacitance-voltage (CV) analysis of metal-oxide-silicon (MOS) capacitor structures immediately following either rapid thermal oxidation (RTO) or rapid thermal annealing (RTA). The experimental results reveal a characteristic peak in the CV response measured following dry RTO and RTA (T>800 °C), as the Fermi level at the Si(100)–SiO2 interface approaches the conduction band edge. Analysis of the QSCV responses reveals a high interface state density across the energy gap following dry RTO and RTA processing, with a characteristic peak density in the range 5.5×1012 to 1.7×1013 cm−2 eV−1 located at approximately 0.85–0.88 eV above the valence band edge. When the background density of states for a hydrogen-passivated interface is subtracted, another peak of lower density (3×1012 to 7×1012 cm−2 eV−1) is observed at approximately 0.25–0.33 eV above the valence band edge. The experimental results point to a common interface state defect present after processes involving rapid cooling (101–102 °C/s) from a temperature of 800 °C or above, in a hydrogen free ambient. This work demonstrates that the interface states measured following RTP (T>800 °C) are the net contribution of the Pb0/Pb1 silicon dangling bond defects for the oxidized Si(100) orientation. An important conclusion arising from this work is that the primary effect of an RTA in nitrogen (600–1050 °C) is to cause hydrogen desorption from pre-existing Pb0/Pb1 silicon dangling bond defects. The implications of this work to the study of the Si–SiO2 interface, and the technological implications for silicon based MOS processes, are briefly discussed. The significance of these new results to thin oxide growth and optimization by RTO are also considered.

Effects of postannealing on the electrical properties of Ta2O5 thin films deposited on TiN/T

The effects of postannealing on the structural and leakage current characteristics of Ta2O5 thin films deposited on a TiN/Ti bottom electrode by chemical-vapor deposition at 350 °C were investigated. The Ta2O5 film of 50 nm thickness shows an amorphous phase and smooth surface morphology after annealing in N2O plasma at 350 °C, but the film treated with rapid thermal annealing in nitrogen (RTN) at 750 °C prior to N2O plasma annealing at 350 °C has an orthorhombic structure and rugged surface morphology. In addition, the TiSi phase also appears in the specimen of RTN-treated Ta2O5 film. Moreover, the residual carbon can be effectively eliminated and the oxygen deficiency can be well compensated by the N2O plasma annealing for both amorphous and crystalline Ta2O5 films. The I–V relation of the amorphous Ta2O5 films is asymmetric with respect to the biasing polarity, which indicates that the leakage current is primarily dominated by the Schottky emission. On the other hand, the crystalline Ta2O5 film has a symmetrical I–V relation, suggesting that the non-Ohmic leakage in the crystalline Ta2O5 film is related to the Poole–Frenkel effect. The barrier heights φB for the non-Ohmic leakage in the amorphous and crystalline Ta2O5 films, as evaluated from the temperature dependence of the I–V relation, are 0.52 and 0.82 eV, respectively.

Thermal Stability and Oxidation Resistance of W, TiW, W(N) and TiW(N) Thin Films Deposited on Si

The thermal stability and oxidation resistance of ∼100-nm-thick W, TiW, W(N) and TiW(N) thin films deposited on Si substrate by rf magnetron sputtering were investigated by X-ray diffraction, resistivity measurement, X-ray photoelectron spectroscopy, Auger electron spectroscopy and scanning electron microscopy. All films showed good thermal stability against rapid thermal annealing in nitrogen (RTN) at 800°C for 1 min, except the W(N) film which decomposed to W and N2 at 800°C. The films also exhibited differences in oxidation resistance against rapid thermal annealing in oxygen (RTO). Both W and W(N) films were significantly oxidized at temperatures above 450 and 500°C, respectively, while TiW and TiW(N) films showed much better oxidation resistance up to temperatures of 750 and 650°C, respectively. In general, nitridized films, i.e., W(N) and TiW(N), exhibit better resistance against oxidation than metallic films. However, TiW films exhibit better oxidation resistance than nitridized films at RTO temperatures ≧600°C due to a change in surface oxide formation from a uniform oxide to a Ti-rich oxide. Once the films were completely oxidized, they were peeled off.

InAs-doped silica films for saturable absorber applications

InAs-doped thin silica films having saturable absorption properties were fabricated using rf sputtering. The films contain semiconductor nanoparticles preserving the zincblende crystal structure of bulk InAs. We have investigated the linear and nonlinear optical as well as structural properties of the films. Rapid thermal annealing in nitrogen was successfully used to tailor the optical absorption saturation dynamics. The films having saturable absorber properties were applied to Kerr lens mode locking initiation in a Ti:Al2O3 laser resulting in self-starting mode locking operation with pulses as short as 25 fs.

Observation of Vacancy Enhancement during Rapid Thermal Annealing in Nitrogen

Observation of Vacancy Enhancement during Rapid Thermal Annealing in Nitrogen

Steady-State Versus Rapid Thermal Annealing of Phosphorusimplanted Pseudomorphic Si(100)/Ge0.12Si0.88

ABSTRACTPseudomorphic Ge0.12Si0.88 films 265 nm thick grown by molecular beam epitaxy on p- Si(100) substrates were implanted with 100 keV 31P at room temperature for a dose of 5 x 1013/cm2. The projected range of the implanted P is about half the epilayer thickness. The implanted layers, together with non-implanted virgin samples, were subsequently annealed by both rapid thermal annealing in nitrogen and by steady-state furnace annealing in vacuum. The damage and strain of the annealed layers were studied by 4He channeling and x-ray doublecrystal diffraction. For a dose of 5 x 1013 P /cm2, both the damage and strain introduced by implantation can be completely removed, within instrumental sensitivity, by rapid thermal annealing at 700 °C for 10 - 40 s. Furnace annealing at 550 °C for 30 min for this sample removes most of the damage and strain induced by implantation. Furnace annealing at 700 °C or higher worsens the crystallinity of the layer and the strain relaxes. Hall measurements were performed on the same samples. Furnace annealing cannot achieve good dopant activation without introducing significant strain relaxation to the heterostructure, while rapid thermal annealing can.

Chemical Surface Modification of Porous Silicon

Resistance to room temperature oxidation and control over wetting properties can be achieved by chemical modification of a porous‐silicon surface. Fourier transform infrared spectroscopy was used in the transmission mode to monitor the surface chemistry of both treated and untreated porous‐silicon samples before and after exposure to humid air at room temperature. Surface modification methods investigated include: (i) vapor‐phase silation using either hexamethyl‐disilazane or trimethylchlorosilane, and (ii) rapid thermal annealing in nitrogen, ammonia, or argon ambients. The silation treatments, carried out in the presence of trace moisture, were successful both in creating surface trimethylsilyl groups and in suppressing room temperature oxidation. Rapid thermal annealing at temperatures as low as 500°C for 30 s eliminates all silicon hydrides. Nitrided porous‐silicon layers are formed at 1100°C in either ammonia or nitrogen; in both cases the silicon nitride infrared absorption peaks scale with the porous layer thickness, indicating that the compounds are distributed throughout the porous layer.

Reaction Kinetics of Sputter-Deposited Ti On SiO2 Substrates during Rapid Thermal Annealing

ABSTRACTIn this paper, the interactions of sputter-deposited Ti on SiO2 substrates during rapid thermal annealing in nitrogen at 550°C - 900°C for 10 - 60 s have been systematically studied using X-ray diffraction, Auger electron spectroscopy, transmission electron diffraction, TEM & cross-sectional TEM, and sheet resistance measurements.

Formation of silicides by rapid thermal annealing over polycrystalline silicon

We have investigated the formation of titanium silicide by rapid thermal annealing in nitrogen and argon ambients over polycrystalline silicon. A sheet resistance of about 3 Ω per square for a 300-Å Ti layer was achieved after 900 °C/10-s annealing treatment, which decreased to about 2 Ω per square after 1100 °C/10-s treatment. The silicides were found to be stable during rapid thermal annealing up to 1100 °C/10 s with no or negligible migration of titanium along the grain boundaries in polycrystalline silicon. An external layer (titanium rich, mixture of titanium oxide and nitride) was observed to form during rapid thermal annealing treatment in the nitrogen ambient, but the surface remained clean in the argon ambient.