Argon Ion Beam Etching Research Articles

Application of ion beam etching technique to the direct fabrication of silicon microtip arrays

A relatively simple and effective method to directly fabricate large-area field emission microtip arrays on n-type silicon wafers is proposed. The presented fabrication approach of silicon microtip devices mainly involves photolithography, thermal shaping and consolidation, argon ion beam etching and sputtering deposition. The measurements show that the silicon field emission microtip devices fabricated have good structural uniformity and electrical characteristics. The center-to-center spacing of microtips fabricated is 50μm and the typical microtip height about 11μm. The scanning electron microscope analysis and the surface style measurements are carried out for the surface morphologies of silicon microtips, such as square-bottom pyramid-shaped microtips, cone-shaped microtips, square-bottom circle-microtips, and circle-bottom circle-microtips. Electrical measurements are performed to obtain the typical field emission properties of the devices. The experiment results show that the method utilized can be applied to fabricate silicon field emission microtip arrays and circle-microtip arrays of larger area.

Properties of YBa 2Cu 3O x and Bi 2Sr 2CaCu 2O x thin film microstrips patterned by argon ion beam

High temperature superconductor YBa 2Cu 3O x (YBCO) and Bi 2Sr 2CaCu 2O x (BSCCO) thin film microstrips were prepared by argon ion beam etching down to a geometrical width W g≈250 nm. A study of transport properties of the superconducting microstrips showed that due to the interaction of accelerated argon ions with the superconductor film the edges of microstrips are damaged to a depth Δ W≈85 nm. The effective width of YBCO microstrip W ef = W g−2Δ W≈80 nm is able to transmit a critical current density above 20 MA/cm 2 at a temperature of 30 K and a zero external magnetic field. The critical current density of similar BSCCO microstrips was several times smaller.

The influence of the argon ion beam etching on the structure of the various set bonding resins

The influence of the argon ion beam etching on the structure of the various set bonding resins

Exchange tab readback transducer using reactive ion etching to define the trackwidth

IrMn was used to stabilize the free layer in exchange tab type magnetic recording readback heads. These heads were fabricated using either reactive ion etching (RIE) or argon ion beam etching (IBE) to define the trackwidth. The two processes were used to eliminate the coupling between the exchange tab material (IrMn) and the free layer (NiFe), which creates a sensitive, nonhysteretic, linear, stable free layer. Wafer level test structures were measured during the head build process and results for the RIE and IBE processes are compared. Transmission electron micrographs were taken. Undercutting of the electrodes can be seen on the RIE processed heads. Spin-stand data for the read heads were compared and the RIE processed heads had a larger low frequency amplitude and sensitivity. Micro-track profiles and tack scans were also taken using the RIE processed heads. The increased process latitude that the RIE process has over the IBE process leads to, on average, overall better performing heads.

Morphological changes of the tooth tissue by means of argon ion beam etching

Morphological changes of the tooth tissue by means of argon ion beam etching

Metallization and interconnection of HTS YBCO thin film devicesand circuits

A comprehensive study of specific contact resistivity and ultrasonicwire bonding yield and strength was carried out on noblemetal-YBa2Cu3O7-x (YBCO) thin film contacts prepared by a varietyof methods and with different YBCO surface conditions. The metallizationtechniques investigated include in situ and ex situ deposition ofgold or silver on YBCO films. The ex situ contacts were made with andwithout lithographic processes. Contact resistivities of less than5×10-8 Ω cm2 at 77 K were achieved for contacts made by therapid ex situ deposition of gold or silver on fresh YBCO films withsmooth surfaces. These contacts also gave a high wire bonding yield andstrength of 10-19 g. High contact resistivities in excess of5×10-4 Ω cm2 and poor wire bonding yield and strength wereobserved for the contacts made by standard lithographic lift-off processes onold YBCO films. Surface treatments using either argon ion beam etching or rfO2 plasma cleaning prior to metallization were found to be useful inreducing the contact resistivity and improving the wire bonding results forthe lift-off contacts. The influence of YBCO film morphology on the contactresistance and wire bonding yield and strength was also studied.

Cylindrical microlens array fabricated by argon ion-beam etching

Cylindrical microlens array fabricated by argon ion-beam etching

XPS and raman investigations of nitrogen ion etching for depth profiling of CuInSe2 and CuGaSe2

The effect of low energy nitrogen and argon ion beam etching on the surface of CuInSe2 single crystals and CuGaSe2 thin films was investigated by (XPS) X-ray photoelectron spectroscopy and Raman measurements. After the removal of the oxidized and contaminated layer the ion-etched surface exhibits an enrichment of In(CuInSe2) or Ga(CuGaSe2). The argon etching results in metallic In(Ga) at the surface due to preferential sputtering. In contrast, the formation of a thin protective InN(GaN) layer on the top of the as-grown material has been observed after reactive nitrogen etching.

Reactive Ion Beam Etching (RIBE) Technique and Instrumentation for SEM Specimen Preparation of Semiconductors

Argon ion beam etching has established itself as an alternative technique to “wet chemical” etching for the preparation of cross sectional SEM specimens of semiconductors [1]. Complementing this technique, we are reporting the results of an iodine RIBE method for improved etching/cleaning capabilities with a measurable increase in etching rates as compared to argon ion beam etching. RIBE systems have been used for decades in the semiconductor research/industry for wafer processing, patterning and surface cleaning. This same technique has also been used for high quality TEM specimen preparation of certain semiconductor materials [2,3]. The beneficial aspects of the iodide RIBE technique for surface etching for a variety of semiconductor structures along with the related instrumentation will be discussed. The semiconductor specimens include traditional ICs and more advanced copper technology devices.The design and construction of the original system used in this work has already been reported [4].

Fabrication and characterisation of YBCO single grain boundary step edge junctions

We use ion beam etching techniques to fabricate YBCO step edge junctions (SEJ) on MgO substrates. Argon ion-beam etching (IBE) of the substrate at angles other than at normal incidence is used to define the step height and angle. Thin (/spl sim/300 nm) magnetron sputtered YBCO films are deposited over the step and patterned using microlithography and cold substrate ion-beam etching techniques. The critical current, I/sub c/ of these SEJs can be controlled by varying the angle of the step etched into the substrate. Fabrication techniques are described which produce one grain boundary at the top of the step and include a smooth return path thereby avoiding a second grain boundary at the bottom of the step. At 77 K, the current-voltage (I-V) characteristics show resistively shunted junction behaviour. These junctions routinely demonstrate reasonably large I/sub C/R/sub N/ products (0.1-0.6 mV), making them suitable for applications in high temperature SQUID devices.

Simulation of mesa structures for III-V semiconductors under ion beam etching

An argon Ion Beam Etching (IBE) simulation model has been developed to investigate the mesa profile evolution in III-V semiconductors' technology. Particular attention has been focused on the sputtering yield angular dependence effect, on the influence of the material and 2D-morphology of the mask onto the pattern transfer. Experimental sputtering yield versus ion incidence angle is injected into the simulation model. The equations which govern the surface evolution, stem from the current method of characteristics. The simulated profiles show that the trenching phenomenon can appear by only considering the variation of the sputtering yield versus the etched surface canting. This is obtained when neither the ion reflection nor the electric field line deviation are taken into account. On the other hand, the slope transfer from the mask to the GaAs and InP substrates is studied.

Raman analysis and field emission study of ion beam etched diamond films

Discontinuous diamond films were deposited on silicon using a microwave plasma chemical vapor deposition system. The diamond deposits were sharpened by argon ion beam etching. Raman spectroscopy was carried out to study the structural change of the diamond after ion beam bombardment. It was found that amorphous sp2 carbon is produced as diamond is being sputtered by the Ar ion beam. The field emission turn-on field was also drastically lowered after sharpening, which, it is speculated, is caused by field enhancement due to change in geometry and/or structural changes (such as amorphization of crystalline diamond into graphitic or amorphous sp2 carbon) by Ar ion irradiation.

Nanolithography of metal films using scanning force microscope patterned carbon masks

Recently, we have shown that small trenches in amorphous carbon films can be produced by a field induced local oxidation with a voltage biased cantilever tip in a scanning force microscope. The depth of the holes and the trenches corresponds to the total thickness of the carbon film while the width was found to be as small as 30 nm. Amorphous carbon films as resist masks for lithography show some advantageous properties, e.g., the stability against halogen plasma etching, negligible chemical reactivity with most substrates and the possibility of removing the mask by oxygen reactive ion etching. In this article, we demonstrate the transfer of the carbon patterns into metal films by argon ion beam etching. By this new method, we produced 10-nm-wide trenches in thin AuPd films. Furthermore, we made small gaps in narrow AuPd lines which have been predefined by conventional e-beam lithography. In order to control and minimize the width of the gaps, the resistance of the conducting lines was controlled in situ during ion beam etching.

Ion beam smoothing of indium-containing III-V compound semiconductors

has been used for smoothing of rough InAs, InP, and InSb surfaces, prepared by argon ion beam etching (IBE). The evolution of the surface roughness and morphology has been studied by atomic force microscopy (AFM) as a function of the N2 RIBE process parameters (ion beam energy, ion beam angle of incidence, and ion dose). A drastic improvement of the surface roughness has been observed for ion beam angles near normal incidence and larger than 70° with increasing ion doses. By using this technique, the initial root-mean-square (rms) roughness of, e.g., InSb of about 40 nm could be decreased to about 1 nm.

Direct-coupled high T/sub c/ DC SQUID gradiometer with single layer YBa/sub 2/Cu/sub 3/O/sub 7/

We have studied first derivative high T/sub c/ dc SQUID (Superconducting QUantum Interference Device) gradiometer from a single layer of Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7/ thin film using pulsed laser deposition (PLD) and argon ion beam etching method. The planar gradiometer consists of two pickup loops coupled directly to dc SQUID with an inductance of about 20 pH in the center of the structure. The gradiometer contains step-edge type junctions of 3 /spl mu/m width and is made on the SrTiO/sub 3/ substrate of 12/spl times/25 mm/sup 2/ in size. The SQUID showed RSJ type junction I-V characteristics with T/sub c/ of 86 K and swing voltage of /spl sim/4 /spl mu/V at 79.3 K. The magnetometer was sensitive only to the gradient of the magnetic field with well balanced null response to uniform fields.

Auger and energy loss spectroscopy analysis of silicon carbide (SiC) surfaces

Auger electron spectroscopy and electron loss spectroscopy were used with different (SiC) samples. The α-SiC(0001) surface of industrial silicon carbide crystals, a (SiC) compound resulting from the implantation of carbon at 30 keV into a silicon substrate and β-SiC layers formed by evaporation of carbon on Si(111) at 1080 °C were analysed. Characteristic Si-LVV and C-KVV Auger spectra of band type structure, recorded in N(E) mode, are related to silicon carbide. These spectra are detected from α-SiC, β-SiC layers and from the substrate layers of the implanted samples as revealed after argon ion beam etching. Heat treatment of the samples in UHV induced the formation of excess carbon at the surface. The Auger and loss spectra of such a C-rich surface are compared to those of pure graphite.

X-ray photoelectron spectroscopic study of the effect of ion etching of silicon carbide on a carbon fiber

Silicon carbide (SiC) was chemical vapor deposited (CVD) onto a carbon fiber to investigate oxidation protection of the coating. This thin film of SiC was analyzed before and after argon and oxygen ion beam etching with core and valence band X-ray Photoelectron Spectroscopy (XPS). The valence band of SiC could be reasonably interpreted by a spectrum generated by a multiple scatter-wave Xα calculation. Oxygen ions were found to oxidize the coating to SiO 2, whereas argon ion etching was found to thin and damage the SiC coating. The SiC coating was found to be susceptible to implantation of argon ions at energies of 6–8 keV, and was also mechanically damaged, causing the exposure of the underlying fiber after etching for up to 10 minutes. The topographical changes associated with argon ion etching were determined using Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). We conclude that SiC may have some significant advantages in oxidation protection as compared to silicon nitride.

Input coils for YBa2Cu3O7 flux-transformers

Input coils for flux transformers at 77 K are fabricated in a YBa2Cu3O7/SrTiO3/YBa2Cu3O7 trilayer technology. The films are deposited on SrTiO3(100) substrates by KrF excimer laser ablation and patterned ex situ by standard photolithography and argon ion-beam etching. Input coils with 10 turns and linewidths down to 10 mu m were prepared and exhibit zero resistance temperatures up to 84 K and critical currents of 0.7 mA at 77 K. Separate crossovers and via-contacts were fabricated on the same chip with critical currents of Ic(77 K)=1 mA (crossover with 10 mu m linewidth) and Ic(77 K)=40 mA (via-contact). The insulation resistance for the 200 nm thick SrTiO3 layer between upper and lower line in a crossover is R(77 K)=590 k Omega .

Raman spectra and laser heating of YBa 2Cu 3O 7 microbridges

Magnetron-sputtered films of YBa 2Cu 3O 7 on MgO(100) substrates are patterned to typically 30 μm wide microbridges by Argon-ion beam etching. Under Raman conditions we analyze the change of critical currents of illuminated bridges as a function of laser power density and cryostat temperature. This allows a precise determination of the temperature in the laser spot and measurements of local electric properties of the bridge, i.e., critical temperatures and critical current densities. When a current flows through the bridge, we compare the temperature induced Raman shift of the B 1g-like plane oxygen phonon at 340 cm −1 with the simultaneous increase of the Raman background signal at low energies. We find that the electronic background appears to have a higher temperature than the phonon system.

The formation of ridges in various directions on (111), (100) and (110) Gd 3Ga 5O 12 substrates

Straight ridge patterns, about 4 μm high, are formed in various directions on (111), (100) and (110) Gd 3Ga 5O 12 single crystal substrates by argon ion-beam etching. This is followed by soaking in phosphoric acid solution in order to optimize the garnet waveguide formation process. The substrate orientation and the ridge direction both have considerable influence on the anisotropic etching of the ion-beam etched ridges in the phosphoric acid solution. The ridges parallel to the [211] direction on (111) substrate are symmetrical; however, their faces are slightly different from those reported for Y 3Fe 5O 12 or Y 3Al 5O 12. The ridges on the (100) and (110) substrates have smooth side walls dependent on the symmetrical garnet crystal structure. Both the intermediate and the final dissolved ridge shapes are similar to the results that have been reported for a garnet single crystal sphere.