Auger Depth Profile Analysis Research Articles

Temperature induced upconversion behaviour of Ho3+-Yb3+ codoped yttrium oxide films prepared by pulsed laser deposition

Pulsed laser deposited Ho3+-Yb3+ codoped yttrium oxide films were grown on silicon substrates in vacuum at different substrate temperatures (373, 573, 773 and 973 K). The deposited films have shown a phase transition on increasing the substrate temperature, as confirmed by the X-ray diffraction analysis. The grain distribution and surface roughness of the deposited thin films have been estimated by atomic force microscopy measurements. In the optical properties study upconversion luminescence at 547, 656 and 758 nm was revealed upon 980 nm excitation. 773 K was found to be the best substrate temperature owing to the thickest deposited layer, as indicated by Auger depth profile analysis of the prepared films. A non-tunable bright green upconversion emission due to the involvement of a two photon process was established and a possible excitation-emission mechanism is explained by using an energy level diagram of the dopant ions.

Corrosion Behavior of Pb-Free Sn-1Ag-0.5Cu-XNi Solder Alloys in 3.5% NaCl Solution

Potentiodynamic polarization techniques were employed in the present study to investigate the corrosion behavior of Pb-free Sn-1Ag-0.5Cu-XNi solder alloys in 3.5% NaCl solution. Polarization studies indicated that an increase in Ni content from 0.05 wt.% to 1 wt.% in the solder alloy shifted the corrosion potential (Ecorr) towards more negative values and increased the linear polarization resistance. Increased addition of Ni to 1 wt.% resulted in significant increase in the concentration of both Sn and Ni oxides on the outer surface. Secondary-ion mass spectrometry and Auger depth profile analysis revealed that oxides of tin contributed primarily towards the formation of the passive film on the surface of the solder alloys containing 0.05 wt.% and 1 wt.% Ni. Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX) established the formation of a Sn whisker near the passive region of the solder alloy obtained from the polarization curves. The formation of Sn whiskers was due to the buildup of compressive stress generated by the increase in the volume of the oxides of Sn and Ni formed on the outer surface. The presence of Cl− was responsible for the breakdown of the passive film, and significant pitting corrosion in the form of distinct pits was noticed in Sn-1Ag-0.5Cu-0.5Ni solder alloy after the polarization experiment.

Metal Dusting Corrosion Initiation in Conversion of Natural Gas to Synthesis Gas

Ni-based industrial alloy samples (INCONEL® 601) were subjected to oxidizing conditions, followed by exposure to a high carbon activity gaseous mixture containing 10% CO in Ar at 550°C in order to reveal factors critical to the initial carbon-formation. Fresh and treated samples were studied via optical-microscopy, SEM, Auger depth-profile analysis, TEM and EPMA. The results show that the extent of carbon formation is dependent on the oxidation parameters, since these affect both the composition and the structure of the 20-60nm thick oxide layer formed. A high oxygen partial pressure during oxidation appears to promote inclusion of Ni or Fe species in the oxide, which subsequently reduce and catalyse the growth of carbon filaments. Surface pre-treatment (i.e. polishing before oxidation) is also found to affect the carbon formation.

Magnetic properties of Fe62Co19Ga19 films deposited on Si(100) substrates

Fe81–XCoXGa19 films, with x = 0−23 atom % Co, were deposited on Si(100) substrates, respectively, by the dc magnetron sputtering method. Film thickness (tf) ranged from 30 to 400 nm. We have done the following experiments on those films: saturation magnetostriction (λS), high-temperature magnetic hysteresis, x-ray diffraction (XRD), atomic force microscopy, Auger-depth profile analysis, and plane-view and/or cross-section transmission electron microscopy. Our main finding is that if x increases from 0 to 19 atom % Co, λS increases from 56 to 152 ppm, and if x continues to increase from 19 to 23 atom % Co, λS decreases. These results indicate that the addition of Co in the Fe81Ga19 alloy is advantageous in enhancing λS, if x is the correct value. From XRD, the Fe62Co19Ga19/Si(100) film comprises the A2 and B2 phases. The mechanism for large enhancement of λS in Fe62Co19Ga19/Si(100) is related to an intrinsic origin. The tf dependence of λS for the Fe62Co19Ga19 films is that: [1] in the range of 110 ≤ tf ≤ 400 nm, λS increases as tf decreases; [2] in the range of 30 ≤ tf ≤ 110 nm, λS decreases as tf continues to decrease. The λS behavior in the regions [1] and [2] is explained based on the modified Neel model. Other physical properties of the Fe62Co19Ga19 films include the following: saturation magnetization 4πMS = 1.8 – 2.0 T, coercivity HC = 35 – 64 Oe, Curie temperature TC = 597 °C, planar (mean) grain size DP = 29.6 nm, and columnar grain size DL ≈ tf.

Ultra High Depth Resolution Auger Depth Profiling by Both Electron and Ion Beams at the Glancing Incidence using an Inclined Specimen Holder

We developed a 85o-high-angle inclined specimen holder which enabled the specimen surface to be irradiated by both electron and ion beams at the glancing incidence. We have investigated the high depth resolution Auger depth profiling analysis with the inclined specimen holder. In consequence, the resulting depth resolution for the GaAs/AlAs super-lattice was found to be independent of the sputtered depth. The highest depth resolution of 1.7 nm was achieved with the Al-LVV Auger peak. The Auger depth profiles of the Si/Ge multiple delta-doped layers revealed that the Ge mono-layer can be measured in-depth profiled with high sensitivity using this inclined specimen holder.

ChemInform Abstract: Influence of Temperature on the Properties of Passive Films Formed on AISI 304 Stainless Steel.

Abstract The nature of the passive film formed on the surface of AISI 304 stainless steel in a borate—boric acid medium (pH ∼9.0), at temperatures between 8°C and 70°C has been investigated, by means of photoelectrochemistry, electrochemical impedance and Auger analysis. An apparent activation energy has been determined for the passive current. Values of bandgap, flatband potential and space charge thickness have been obtained. An Arrhenius type of relationship was detected between the density of charge carriers and T, leading to an activation energy of 0.1 eV, which was associated with the ionization energy of the donor species. This characterization of the film is completed by a quantitative determination of its chemical composition and thickness which were derived from Auger depth profile analysis.

Scanning Auger of a specific via interface in an integrated circuit using a novel focused ion beam sample preparation technique

Auger depth profile analysis can be impeded by surface roughening during ion sputtering. This is especially noticeable when analyzing semiconductor devices because of the variety of materials that are susceptible to roughening, as well as the importance of very thin interfaces. A novel technique is presented in this article, which combines scanning Auger analysis with focused ion beam (FIB) thinning for analysis of single via interfacial structures in integrated circuit devices. After a failing structure was identified by electrical fault isolation techniques, FIB was used to remove all of the materials from the top of the device. The materials include polyimide, passivation, metal layers, and dielectric layers. The layers were removed to a level approximately 100Å above the via interface under a tungsten plug. A scanning Auger instrument was then used for Auger depth profiling of the single via. A thin oxidized interface was observed between Ti∕TiN glue layer and antireflection coating (ARC) TiN and was identified as the cause of the via failure. It would have been impossible for conventional sputter depth profiling to detect this thin oxidized layer buried under several layers of materials. Further investigation showed that the interfacial oxide is caused by backsputtering of ARC TiN during via etch and rf sputtering before Ti∕TiN glue deposition.

10 nm 두께의 니켈 코발트 합금 박막으로부터 제조된 니켈코발트 복합실리사이드의 미세구조 분석

We fabricated thermally-evaporated 10 nm-Ni/(poly)Si and 10 nm-/(Poly)Si structures to investigate the microstructure of nickel silicides at the elevated temperatures required lot annealing. Silicides underwent rapid annealing at the temperatures of for 40 seconds. Silicides suitable for the salicide process formed on top of both the single crystal silicon actives and the polycrystalline silicon gates. A four-point tester was used to investigate the sheet resistances. A transmission electron microscope and an Auger depth profilescope were employed for the determination of vortical microstructure and thickness. Nickel silicides with cobalt on single crystal silicon actives and polycrystalline silicon gates showed low resistance up to and , respectively, while the conventional nickle monosilicide showed low resistance below . Through TEM analysis, we confirmed that a uniform, -thick silicide layer formed on the single-crystal silicon substrate for the Co-alloyed case while a non-uniform, agglomerated layer was observed for the conventional nickel silicide. On the polycrystalline silicon substrate, we confirmed that the conventional nickel silicide showed a unique silicon-silicide mixing at the high silicidation temperature of . Auger depth profile analysis also supports the presence of this mixed microstructure. Our result implies that our newly proposed NiCo-alloy composite silicide process may widen the thermal process window for the salicide process and be suitable for nano-thick silicides.

Microstructure Characterization for Nano-thickIr-inserted Nickel Silicides

Department of Materials Science and Engineering, University of Seoul, Cheonnong-dong, Tongdaemun, Seoul 130-743, KoreaElectrical Engineering, Unversity of Texas at Dallas, 2601 N. Floyd Rd., Richardson, TX 75083, USA(2007 1 23 , 2007 4 11 )Abstract We fabricated thermally-evaporated 10 -Ni/(poly)Si and 10 -Ni/1 -Ir/(poly)Si structures to investigatethe microstructure of nickel monosilicide at the elevated temperatures required for annealing. Silicidesunderwent rapid at the temperatures of 300~1200 for 40 seconds. Silicides suitable for the salicide processformed on top of both the single crystal silicon actives and the polycrystalline silicon gates. A four-point testerwas used to investigate the sheet resistances. A transmission electron microscope(TEM) and an Auger depthprofile scope were employed for the determination of vertical section structure and thickness. Nickel silicideswith iridium on single crystal silicon actives and polycrystalline silicon gates showed low resistance up to 1000and 800, respectively, while the conventional nickle monosilicide showed low resistance below 700. ThroughTEM analysis, we confirmed that a uniform, 20 -thick silicide layer formed on the single-crystal siliconsubstrate for the Ir-inserted case while a non-uniform, agglomerated layer was observed for the conventionalnickel silicide. On the polycrystalline silicon substrate, we confirmed that the conventional nickel silicideshowed a unique silicon-silicide mixing at the high silicidation temperature of 1000. Auger depth profileanalysis also supports the presence of thismixed microstructure. Our result implies that our newly proposediridium-added NiSi process may widen the thermal process window for the salicide process and be suitable fornano-thick silicides. Key wordsNiSi, Ir-inserted Nisilicide, TEM, Auger depth profiling.

Formation and electronic properties of oxygen annealed Au/Ni and Pt/Ni contacts to p-type GaN

The formation of Au/Ni and Pt/Ni contacts to p-GaN has been examined with Auger depth profiling and x-ray photoelectron spectroscopy analysis and compared to circular transmission line measurements of their respective transport properties. The metal bilayers were deposited by radio frequency argon ion sputtering, and the samples were annealed at different temperatures in a 10−3 mbar oxygen ambient. Both contacts were distinctly non-ohmic as deposited. Ohmic behaviour was achieved after oxidation at temperatures above 400 °C, and the two contacts were found to have comparable performance, with a lowest specific contact resistance ρc = 1.0 × 10−2 Ω cm2 for the Pt/Ni contact after annealing at 400 °C and ρc = 1.3 × 10−2 Ω cm2 for the best Au/Ni contact annealed at 600 °C. Au and Pt both serve to ensure a highly conducting contact layer after annealing in oxygen and help lower the Schottky barrier at the metal/p-GaN interface by virtue of their large work functions. Distinct differences were observed in the alloying properties of the Pt/Ni and the Au/Ni contact layers, however. While Pt and Ni interdiffuse to form a uniform alloy upon annealing in oxygen at 600 °C, Ni diffuses outwards to form surface nickel oxide for the Au/Ni metallization. Trace amounts of Ga were observed at the surface after annealing at 600 °C for the Pt/Ni and the Au/Ni bilayers alike, albeit in considerably larger measure for Pt/Ni. We believe that this surface Ga derives from a thermally activated reaction between Ni and GaN, which adversely affects the contact performance. The outward diffusion of Ni upon thermal oxidation of the Au/Ni contact appears to inhibit the rate of this interface reaction, which speaks in favour of using Au over Pt in ohmic contacts to p-GaN. Preconditioning of the p-GaN surface by deposition and subsequent removal of a thin coating of Ni are found to improve the contact performance, provided the coating is not annealed before removal.

Ohmic Contact to Phosphorous-Doped ZnO Using Pt ∕ Ni ∕ Au for p - n Homojunction Diode

The electrical properties of single Pt and Pt multilayer contacts on moderately doped were investigated. Although linear current–voltage characteristics were observed for all samples, a sample that was annealed for at a temperature above resulted in an ohmic contact with good characteristics. The best ohmic contact to p-type was obtained using a multilayer contact that was annealed at for under a ambient, showing a specific contact resistance of . The fundamental mechanisms for the lower contact resistivity of contacts are discussed based on glancing-angle -ray diffraction results and Auger depth profile analysis of the multilayer alloying process. Furthermore, we fabricated a p–n homojunction using and as the p-type and n-type ohmic contact metal, respectively. The threshold voltage was determined to be about , comparable to the bandgap energy of .

Magnetic properties of face-centered cubic Co films

We deposited face-centered cubic (FCC) Co films on glass substrates by sputtering. From Auger-depth profile analysis, we found that there is one CoO layer, about 13 /spl Aring/ thick, lying on the top surface of the Co film, and another CoO layer, about 37 /spl Aring/ thick, lying within the Co/glass interface. At room temperature, the thin CoO film is supposed to be paramagnetic. However, because of the proximity effect between CoO and Co, the CoO layer may become ferromagnetic, with saturation magnetization M/sub o/. By fitting the saturation magnetization (M/sub s/) data of the whole Co/CoO film as a function of (1/t/sub f/), where t/sub f/ is the Co thickness, we can prove that the last conjecture is correct, and the M/sub o/ of the CoO layer is indeed not zero. Both the t/sub f/ dependence of the magnetostriction constant (/spl lambda//sub s/) and the t/sub f/ dependence of the coercive field (H/sub c/) show a two-region characteristic. The dividing line for the former quantity is at t/sub f/ = 88 /spl Aring/, and for the latter it is at t/sub f/ = 120 /spl Aring/. When crossing such a dividing line, there is a discontinuous jump in /spl lambda//sub s/ (or H/sub c/). These phenomena occur because the lattice-strain and magnetoelastic effects within the CoO layer dominate the /spl lambda//sub s/ and the H/sub c/ behavior in ultra-thin (t/sub f/ < 88 /spl Aring/) Co films. In this region, the roughness-to-thickness ratio (S/sub q//t/sub f/) may also affect /spl lambda//sub s/. Finally, there seems to be no connection between the grain size (D) and H/sub c/.

Ohmic Contact Behavior of Pt/Ni/Au to p-ZnO

ABSTRACTThe electrical properties of single Pt (30 nm) and Pt (30 nm)/Ni (30nm)/Au(50nm) multilayer contacts on moderately doped p-ZnO (Na = 5.0 × 1017 /−3) were investigated. Although linear current-voltage characteristics were observed for all samples, a sample that was annealed for 1 min at a temperature above 500 °C resulted in an ohmic contact with good characteristics. The best ohmic contact to p-type ZnO was obtained using a Pt/Ni/Au multilayer contact that was annealed at 600 °C for 1 min under a N2 ambient, showing a specific contact resistance Rc of 1.97 × 10−5 Ω cm2. The fundamental mechanisms for the lower contact resistivity of Pt/Ni/Au contacts are discussed based on glancing angle x-ray diffraction results and Auger depth profile analysis of the multilayer alloying process. Furthermore, we fabricated a ZnO p-n homojunction using Pt/Ni/Au and Ti/Au as the p-type and n-type ohmic contact metal, respectively. The threshold voltage was determined to be about 3.7 V, comparable to the bandgap energy of ZnO.

Magnetostriction and Young's modulus of [Fe 15Ni 85/Fe 25Ni 75] multilayers

A series of ferromagnetic [A x B 60− x ] 2 multilayers, where A=Fe 15Ni 85, B=Fe 25Ni 75, and x is the thickness of layer A in nanometer, were manufactured by the vapor evaporation method. Three measurements were carried out on each sample: the Auger depth–profile analysis, a measurement of Young's modulus E f by the nano-indentation system, and the measurement of saturation magnetostriction λ s by the optical-cantilever system. Bulk and thin-film samples have different Young's modulus, and, moreover, in the multilayer, the modulus E f becomes a nonlinear function of x. A set of λ s data derived using the measured E f is compared with data based on the bulk value E f=2.0×10 11 N/m 2. The deposition temperature here is T s=200 °C. With increasing T s (here up to 400 °C), the interfacial mixing increases as well. The deviation Δ λ s of magnetostriction from theoretically predicted linear behavior is found to be oscillatory at low T s (where Δ λ s changes signs), but monotonic at high T s (where Δ λ s maintains the same sign). A qualitative explanation of these phenomena is provided.

Deposition of Copper Thin Films on Titanium Nitride Layer Prepared by Flow Modulation CVD Technology

Copper (Cu) thin films have been deposited onto titanium nitride (TiN) layer which was previously prepared by flow modulation chemical vapor deposition (FMCVD technology. The diffusion barrier properties of the TiN layer to Cu have been studied depending upon the post-annealing and the sample preparation conditions of the TiN layer. The Cu deposition has performed by RF magnetron sputtering with 5N target in the high vacuum ambient. The FMCVD process has carried out in a single CVD chamber by switching TiCl4 flow to the argon flow cyclically, which creates sequential deposition of TiN layer and chlorine reduction process. The higher flow modulation cycle and Ar purge time during the TiN layer growth have been observed to provide the better diffusion barrier property in Auger depth profile and X-ray diffraction analysis.

Effects of ozone as an oxygen source on the properties of the Al 2O 3 thin films prepared by atomic layer deposition

The atomic layer deposition (ALD) technique has been used to grow ultra-thin and conformal aluminum oxide (Al 2O 3) thin films on patterned poly-Si (1 0 0) substrates using trimethylaluminum (TMA), Al(CH 3) 3, and ozone (O 3) as the starting precursors for Al and O, respectively. The growth rate and the thickness uniformity have been studied, along with Auger depth profiling and Rutherford back scattering (RBS), to ascertain the quality of the films. The novel head-injector type ALD system used in this study produced highly uniform (with non-uniformity <2%) conformal Al 2O 3 films over a large deposition area of 8 in. diameter substrates. The growth rate was found to be about 0.85 Å per cycle under this experimental condition. It has been found that the use of O 3 does not significantly alter the growth rate or the thickness uniformity when compared with H 2O-based Al 2O 3 films. However, substrate temperature plays a crucial role on the film growth. In case of O 3-based Al 2O 3 films, the growth rate and the step coverage were found to increase with increasing substrate temperature in our experimental range, unlike H 2O-based Al 2O 3 films, where the growth rate drops beyond 350 °C. The increase in the deposition rate and the better step coverage with the increase in the substrate temperature confirms that the growth of O 3-based Al 2O 3 films is controlled by the amount of the decomposed O 3. An excellent step coverage and a large aspect ratio (∼ 40:1) prove a very good quality of the films with a very low (<1%) level of carbon contamination, as has been confirmed from Auger depth profile analysis. RBS analysis results confirm that the Al 2O 3 films are near stoichiometric (Al 2.2O 2.8). The XPS analysis of Al 2O 3 films grown revealed only an oxidized Al 2p peak.

Flux-free direct chip attachment of solder-bump flip chip by Ar + H2 plasma treatment

The flux-free flip-chip bonding process using plasma treatment was investigated. The effect of plasma-process parameters on Sn oxide-etching characteristics was evaluated by Auger depth-profile analysis. The die-shear test was performed to evaluate the adhesion strength of an Sn-37mass%Pb and Sn-3.5mass%Ag solder-bump flip chip that was bonded after plasma treatment. The Ar + H2 plasma treatment reduced the thickness of the oxide layer on the Sn surface. The addition of H2 to the Ar plasma improved the oxide-etching characteristics. A low chamber pressure was more effective in oxide etching. The die-shear strength of the plasma-treated Sn-Pb and Sn-Ag solder flip chip was higher than that of the nontreated chip but lower than that of the fluxed chip. The difference in the die-shear strength between the plasma-treated specimen and the nontreated specimen increased with increasing bonding temperature. The plasma-treated flip chip fractured at the solder/top-surface metallurgy (TSM) interface at low bonding temperature, but at the solder/ under-bump metallurgy (UBM) interface at high bonding temperature.

Effects of CrAl underlayer and intermediate layer on the properties of CoCrPtTa thin film media

This study investigates the effects of CrAl underlayer and intermediate layer on the magnetic properties, crystallographic texture, and thermal stability of CoCrPtTa thin film media. Enhancement of coercivity and thermal stability factor of CoCrPtTa/CrAlx thin film media were observed when the Al concentration in the CrAl underlayer was varied from 0 to 14 at. %. We also observed an improvement in the in-plane crystallographic texture and a reduction in the magnetic switching volume and intergrain interaction. Results from the interdiffusion study using Auger depth profiling analysis, and ΔM measurement showed that the decrease of switching volume and intergrain interaction may be attributed to Al diffusion and/or Al-enhanced Cr diffusion into the grain boundary of the magnetic layer. Compared to CoCrPtTa/Cr media, we found that high coercivity, good in-plane crystallographic texture, and magnetic isolation for CoCrPtTa/CrAl media could be achieved at lower substrate temperature. This study has also shown that a CrAl intermediate layer could be used to further enhance the magnetic, crystallographic texture, and thermal stability properties of the CoCrPtTa thin film media.

Composition, Structure, Stress, and Coercivity of Electrodeposited Soft Magnetic CoNiFe Films: Thickness and Substrate Dependence

The properties of soft magnetic CoNiFe films electrodeposited in the presence of saccharin and sodium lauryl sulfate additives were studied in terms of their thickness and substrate dependence. Auger depth profile analysis of the elemental composition in CoNiFe films electrodeposited over different substrates 1.0 T NiFe, Cu) demonstrate that the average composition at the substrate interface and bulk deposited films remains constant. X-ray diffraction (XRD) measurements reveal the existance of mixed phase with larger amounts of bcc crystallites near the substrate side of the films, i.e., at the lower thickness. XRD and transmission electron microscopy measurements revealed a larger grain size at the CoNiFe/substrate interface. The measured average stress is both substrate- and thickness-dependent. The easy-axis coercivity, follows the Neel’s relation (t is the thickness and c is a constant). It was found that the value of the exponent n is substrate dependent. Mechanisms related to the coercivity of CoNiFe films deposited over different substrates (1.0 T NiFe, Cu, high magnetic moment CoNiFe) are discussed in terms of material properties of these magnetic films. © 2001 The Electrochemical Society. All rights reserved.

Auger depth profile analysis and EFTEM analysis of annealed Ti/Al-contacts on Si-doped GaN

Ti/Al (10 nm/100 nm) bilayer contacts on Si-doped GaN were heat treated for 30 s at 600 and 650°C. The microstructure of the contacts was analysed by Auger depth profiling, SEM and EDX analysis and energy filtering TEM using electron spectroscopic imaging (ESI). The experiments show a strong interdiffusion of Al and Ti leading to the formation of an intermetallic compound. A complex, spatially inhomogeneous structure consisting of an Al-rich phase, a Ti–Al intermetallic compound and regions containing Al-oxide is formed, while the GaN is still covered by a thin, homogeneous Ti-rich layer. A thickness of 2.5 nm was obtained for the Ti-rich layer in the contact heat treated at 650°C. The combination of complementary results from Auger depth profiling, SEM analysis with EDX and ESI provides a comprehensive characterisation of the complex contact structure. The results will be discussed in terms of the contributions and specific advantages of the individual techniques.