Sputter Etching Research Articles

Local sputter etching by micro plasma jet in SEM

A local high pressure micro plasma jet was proposed for micro scale local sputter etching in a vacuum system. A small orifice gas nozzle as an anode was placed in a Scanning Electron Microscope (SEM) chamber to produce the local high gas pressure and supply Argon gas for DC plasma generation at a short gap distance. The characteristics of local sputter etching by the micro plasma jet were studied. At DC power of 1.68 mW, a silicon sputtering rate of approximately 0.01 μm/s was achieved by using an orifice 40 μm in diameter at 2.5 sccm gas flow rate and 100 μm gap distance. The sputtered area was 60 μm in diameter.

Duplex processing for increased adhesion of sputter deposited Ti1-xAlxN coatings on a Fe–25%Co–15%Mo tool material

Recently, carbide-free alloying systems with yield strength Rp0.1 of up to 4000MPa and outstanding thermal stability are available, which offer the possibility to elevate coating deposition temperatures up to 600°C. The present work demonstrates that the limited Ti1−xAlxN coating adhesion on a Fe–25%Co–15%Mo grade caused by the absence of carbides in the substrates can be significantly improved from HF 4 to HF 2 in the Rockwell adhesion test by plasma-assisted nitriding during sputter etching. X-ray photoelectron spectroscopy measurements reveal that the nitrogen diffusion zone is confined to the first few nanometre of the substrate surface, while mainly Mo–N and partly Fe–N bondings are formed. X-ray diffraction exhibits the formation of cubic Mo2N in the nitrided layer. The coatings show a single-phase face-centered cubic Ti1-xAlxN structure tending to a preferred (110) growth orientation with increasing nitriding time. Tribological tests performed at room temperature and 650°C indicate superior wear performance of duplex Ti1-xAlxN coated Fe–25%Co–15%Mo.

Development of a Bi2Te3-based thermoelectric generator with high-aspect ratio, free-standing legs

Abstract

Morphological Evolution during Growth and Erosion on Vicinal Si(100) Surfaces: From Electronic Structure Analyses to Atomistic and Coarse-Grained Modeling

ABSTRACTStepped Si(100) surfaces exhibit alternating stiff SA and meandering SB steps, and thus constitute a so-called AB-vicinal surface. Both growth by Molecular Beam Epitaxy (MBE) or Chemical Vapor Deposition (CVD), and erosion by ion sputtering or chemical etching, induce step pairing, although different factors contribute. In addition, more complex pattern formation often occurs during step train motion. We synthesize recent developments in modeling of these processes ranging from ab-initio electronic structure approaches for key surface energetics, to atomistic lattice-gas modeling, to coarse-grained sharp-interface (front-tracking) and smeared-interface (phase-field) step dynamics approaches. We briefly describe development of new formalisms related to coarse-grained approaches, as well as selected results for step pairing.

Application of sputter etching treatment to the formation of semiconducting silicide film on Si substrate

Application of sputter etching treatment to the formation of semiconducting silicide film on Si substrate

Structural and electrical characterization of silicided Ni/Au contacts formed at low temperature (<300 °C) on p-type [001] silicon

Silicided Ni/Au contacts with very low contact resistance were realized on p-type [001] silicon at low temperature by ex-situ or, alternatively, by in situ annealing processes. During the ex-situ annealing, performed at 200 °C for 10 s, a uniformly thin (14 nm) Ni2Si layer was formed having an extremely flat interface with silicon thanks to the trans-rotational structure of the silicide. During the in situ annealing, promoted by a sputter etch processing (T < 300 °C), a 44 nm-thick silicide layer was formed as a mixture of trans-rotational NiSi and epitaxial NiSi2, domains. In both cases, using a low thermal budget has guaranteed a limited consumption of silicon during the reaction process and a good adhesion with the substrate avoiding gold contaminations. As a consequence of the presence of trans-rotational domains, wherein a pseudo-epitaxial relationship between the silicide and the silicon lattices is established, an ohmic behavior was observed in a wide range of substrate doping (3.5 × 1018 ÷ 3 × 1019 B/cm3) for both annealing processes (in situ and ex-situ). On the other hand, conventional TiNiAu and CrNiAu contacts showed, in the same range of B doping concentration, a rectifying behavior with systematically higher specific contact resistance values (Rc) compared to those of the Ni silicided contacts.

Ion sputter etching of ZnO:Ga thin film surfaces

In this article the modification of surface morphology of ZnO:Ga (GZO) thin films by ion sputter etching is presented. GZO thin films were prepared at room temperature on Corning glass substrates by both normal and oblique angle RF diode sputtering from ZnO:2%Ga ceramic target in Ar gas. Ion sputter etching was performed by RF re-sputtering of GZO thin films on substrates. During RF sputter etching, Ar pressure of 1.3Pa and RF power of 250W were kept constant, only the time of sputter etching was changed. Ion sputter etching had remarkable influence on surface morphology of GZO thin films: increase of roughness Rq and the “homogenization” of film surfaces, i.e. skewness (Rsk) and spikiness (Rku) parameters (Rsk≈0/Rku≈3).Surface root-mean-square roughness (Rq) increased from 15.3nm (after sputter deposition) to 29.1nm (after ion sputter etching). For obliquely thin films increased from 16.5nm (after sputter deposition) to 38.2nm. Changes of these parameters Rq, Rsk, Rku influenced optical properties of GZO films, increased Haze parameter up to values 7.7% and width of optical band gap 3.44eV, respectively.

ZnO Field-Effect Transistor Fabricated by RF Magnetron Suputtering and Lithographic/Wet Etching Processes

The fabrication of zinc oxide （ZnO）based thin-film field-effect transistors (TFTs) on p-Si substrates by rf magnetron sputtering, photolithography and wet etching processes was presented. Bottom-gate-type thin film transistors using ZnO as an active channel layer were constructed, and their properties were characterized by atomic force microscope, X-ray diffraction and I-V measurements. The fabricated ZnO transistors exhibited enhancement mode characteristics with the on-to-off current ratio of ∼105 and the threshold voltage of 10V. It is believed that the ZnO TFTs fabricatd by the simple and low-cost technique could be applicable to electronic devices.

Investigation on etch characteristics of MgO thin films using a HBr/Ar plasma

Etch characteristics of MgO thin films were investigated using an inductively coupled plasma reactive ion etcher in a HBr/Ar plasma. As the concentration of HBr gas increased, the etch rate of MgO thin films gradually decreased, but the etch rate of Ti hard mask showed initial decrease and then increased with increasing HBr concentration. The etch profile of MgO films was improved with increasing HBr concentration and a high degree of anisotropy in etch profile was achieved at 30% HBr/Ar gas. Based on the etch characteristics and surface analysis by X-ray photoelectron spectroscopy, it can be concluded that the etch mechanism of MgO thin films in a HBr/Ar gas does not follow the reactive ion etch mechanism but the sputter etching mechanism with the assistance of chemical reactions on the film surfaces.

Synthesis of Ni80Fe20 and Co nanodot arrays by self-assembling of polystyrene nanospheres: magnetic and microstructural properties

Array of dots have been designed by assembling a monolayer of polystyrene nanospheres (PN) on sputtered thin films having Ni80Fe20 and Co composition with different thickness, ranging in the interval 20 ÷ 80 nm. Subsequently the films are nanopatterned using the nanospheres as a mask during sputter etching with Ar+ ions. A Reactive Ion Etching (RIE) process before sputter etching is used to control the final diameter of the magnetic dots that thus can be tailored as desired (typically ranging in the interval 250 ÷ 400 nm depending on the PN starting diameter). In addition, electron beam lithography has been exploited to obtain arrays of dots in Ni80Fe20 thin films having approximately the same mean size and dot distance as in self-assembled samples. All films have been routinely characterized by SEM and AFM microscopy to evaluate the microstructure. Magnetic domain patterns at magnetic remanence and in the demagnetised state have been imaged by MFM microscopy technique. Room-temperature hysteresis properties have been measured by an alternating gradient force magnetometer. In general, the magnetization process in all patterned films has been observed to have features typical of a vortex whose nucleation field depends on sample thickness and mean dot dimension. A comparison between magnetic arrays of Ni80Fe20 dots prepared by self-assembling of polystyrene nanospheres and electron beam lithography is presented to rule out the role of microstructure (i.e., order, size, and mutual distance of the magnetic dots) on magnetic properties.

Etch characteristics of FePt magnetic thin films using inductively coupled plasma reactive ion etching

Etch characteristics of L10 FePt thin films masked with TiN films were investigated using an inductively coupled plasma (ICP) reactive ion etching in a CH 3OH/Ar plasma. As the CH 3OH gas was added to Ar, the etch rates of FePt thin films and TiN hard mask gradually decreased, and the etch profile of FePt films improved with high degree of anisotropy. With increasing ICP rf power and dc-bias voltage to substrate and decreasing gas pressure, the etch rate increased and the etch profile becomes vertical without any redepositions or etch residues. Based on the etch characteristics and surface analysis of the films by X-ray photoelectron spectroscopy, it can be concluded that the etch mechanism of FePt thin films in a CH 3OH/Ar gas does not follow the reactive ion etch mechanism but the chemically assisted sputter etching mechanism, due to the chemical reaction of FePt film with CH 3OH gas.

RF sputtering of epitaxial lead chalcogenide films in argon and krypton plasma

The measurements of sputtering etch rates for monocrystalline (1 1 1)-oriented epitaxial films of semiconductor binary compounds PbTe, PbSe, PbS in RF high-density low-pressure inductively coupled argon and krypton plasma were performed. Films with 1–5 µm thickness were grown on Si(1 1 1) and BaF2(1 1 1) substrates using molecular beam epitaxy. Sputtering was carried out with the energy of Ar+ and Kr+ ions of 20–400 eV. The sputtering etch rates of the binary lead chalcogenides are demonstrated to have abnormally high values in comparison with the basic semiconductor materials of microelectronics. The sputtering yield values for PbTe, PbSe, PbS for the average energy of the argon ions of 200 eV are practically equal (0.46 ± 0.05 molecule/ion) and vary linearly with the variation of the ion energy. Substitution of the plasma discharge gas from the argon to krypton does not result in a significant change in the sputtering yield of lead chalcogenides. The physical principles of the observed phenomena are discussed.

Thickness dependence of crystalline state in FeZrNbCuB thin films obtained by sputter deposition

Differential scanning calorimetry, hysteresis measurements, X-ray diffraction, Mössbauer spectroscopy and transversal Kerr effect have been used to study the thickness and temperature dependence of magnetic properties and crystalline state of Fe 84Zr 3.5Nb 3.5B 8Cu 1 (at.%) thin films. Results indicate that a decrease of the saturation magnetization with increasing film thickness can be ascribed to the presence of a crystalline α-Fe phase at the early stages of film growth, followed by the deposition of the amorphous alloy. Thinner films, which have a significant crystalline phase in the as-prepared state, display less prominent crystallization features, whereas thicker films, with a significant amorphous phase in the as-prepared state, are characterized by much more pronounced crystallization effects, that are confirmed by Mössbauer and Transversal Kerr Effect measurements. Progressive thinning of a film by means of sputter etching allows to reduce the amorphous component, leading to the expected increase of saturation magnetization as the thickness decreases.

工具鋼のスパッタエッチングによって形成した微細突起物の光反射特性

Argon ion sputter etching was applied to three kinds of tool steels at a radio frequency power of 50 W to 250 W for 0.5 ks to 16.2 ks. Pillar-shaped protrusions with diameters or widths of 100 nm to 1 μm were formed on the surface of SKH51 and SKD5 steel plates, and conical protrusions of similar size were formed on the surface of the SKD61 steel plate. The size of both types of protrusions was typically comparable to the wavelength range of visible light, i.e. 400 nm to 800 nm. The absolute reflectance of the SKH51 steel surface was about 0.3% with a sputter power of 200 W and a sputter etching time of 10.8 ks. The reflectance is nearly constant and is independent of the 400 nm to 800 nm wavelength and incident angle of less than 60°. This indicates that sputter etching of tool steels can produce satisfactory anti-reflection bodies with excellent mechanical properties.

Cr/Cu/Al/Cr薄膜电极的防氧化性能

Novel Cr/Cu/Al/Cr thin film electrodes were prepared by DC magnetron sputtering and wet etching technology,in which Al thin film was used as the protective layer for Cu layer.The change of the crystal structure,surface morphology and electric resistivity of the thin films and electrodes before and after heat treatment were studied.The Al layer played a key role as an oxygen diffusion barrier layer,for its protection,the Cr/Cu/Al/Cr thin film still had good thermal stability when the heat treatment was below 600 ℃.Meanwhile,the oxidation diffusion from the lateral edge of the electrodes as the temperature increased caused the decrease of the conduction of the electrodes.The electric resistivity was increasing obviously after 500 ℃ heat treatment,and the oxidation region was expanded from the edge to the surface of the electrode.Nonetheless,the thin film electrode fulfilled the requirements of field emission device for its stable resistance when post annealing tempera-ture was 430 ℃,which was 7.2×10-8 Ω·m.Based on the new electrode,the FED device was fabricated for verifying its oxidation resistance.

Fabrication of 2D silicon nano-mold based on sidewall transfer

A method based on the sidewall transfer technique for fabricating two-dimensional (2D) nano-mold on a silicon substrate was developed. Instead of using expensive nanolithography, the authors fabricated 2D silicon nano-mold using standard ultraviolet lithography, conformal deposition of gold by radio frequency sputtering, argon sputter etching and deep reactive ion etching (DRIE). This technique enables the generation of very fine geometries with nanoscale dimensions without the electron-beam (e-beam) lithography equipment or other additional lithography techniques. Based on SF 6 , O 2 and C 4 F 8 plasmas, a vertical mold profile and a minimum scallop size of 30 nm were obtained by optimising DRIE parameters. For smooth mold surfaces, the authors report and demonstrate a new mechanism of removing grass obtained during inductively coupled plasma etching. With this technique, very uniform 2D silicon nano-molds consisting of 200 nm wide, 200 nm high and 4.3 mm long bar arrays have been successfully fabricated.

Three-Dimensional Micro-Coil Oscillator Fabricated with Monolithic Process on LSI

Integration technique of three-dimensional micro coils on high-performance RF-LSI is one of the key technologies to realize future wireless telecommunication services and hypersensitive capacitance sensor systems. We design and fabricate monolithic three-dimensional micro coils on LSI substrate. The micro-coil has long legs, which will minimize electromagnetic coupling to the LSI substrate. We succeed in confirming the basic operation of the integrated oscillator circuit in GHz frequency range. It is conformed that process damages by plasma ashing, heating at 200 degrees Celsius, and sputter etching process are not observed in the oscillation performance.

Macro and quasi‐mesoporous silicon by self‐assembling and metal assisted etching

AbstractThe combination of two recent techniques developed in the last years demonstrates the possibility to obtain regular and semi‐ordered macro and mesopores on any type of silicon substrates and with holes diameter ranging from 800 to 60 nm and less. Self‐assembling of polystyrene nanospheres (PSNS) is obtained by floating technique, then the 2D crystal is lifted on a silicon substrate with a 30 nm silver thin film deposited by thermal evaporation or sputtering. The nanospheres are then reduced in diameter by reactive ion etching (RIE) in oxygen plasma, then the samples are exposed to Ar ions sputter‐etching (SE) for thin film structuration. At this point of the process the polystyrene nanosphere mask is removed and a metal assisted etching (MAE) of few minutes is performed. Ordered and regular pores of diameters ranging from 500 to 60 nm have been obtained.magnified image Macropores (450 nm) obtained by self‐assembly nanolithography and metal assisted etching.

Glassy alloy composites for bit-patterned-media

With the aim of developing a novel perpendicular bit-patterned-media, combined process of thermal imprinting of glassy alloy thin film and embedding Co/Pd multilayer was developed. Nano hole array with a hole diameter of 30 nm was successfully formed onto Pd-based glassy alloy thin film by thermal imprinting. Co/Pd multilayer was overlaid on a textured Pd-based glassy alloy thin film. After finishing by sputter etching, prototype bit-patterned-media was prepared. Switching behavior examined under magnetic field of ±10 kOe reveals that the isolated magnetic dots began to switch at 10 kOe. These results suggest that the prototype composite has a strong possibility for the realization of next generation bit-patterned-media with high data density.

Investigation of the current injection on JC of a HTS YBCO ring

The effect of the current injection from the ferromagnetic La0.7Sr0.3MnO3 (LSMO) electrode into high temperature superconducting Y1Ba2Cu3O7−x thin film ring on the critical current of the ring was investigated at 77 K using contactless method. The structures were prepared using magnetron sputtering, conventional photolithography and wet etching procedures. The critical current was determined from the response of the HTS ring to the AC magnetic field. The experiments demonstrated a sensitivity of the critical current to the current injection process, especially in the case of LSMO current-injecting electrode. The paper presents the experimental results and discusses possible mechanisms of the observed effects.