Interest In Microelectronics Research Articles

Nonsaturating Linear Magnetoresistance Manifesting Two-Dimensional Transport in Wet-Chemical Patternable Bi2O2Te Thin Films.

Two-dimensional (2D) materials with exotic transport behaviors have attracted extensive interest in microelectronics and condensed matter physics, while scaled-up 2D thin films compatible with the efficient wet-chemical etching process represent realistic advancement toward new-generation integrated functional devices. Here, thickness-controllable growth and chemical patterning of high-quality Bi2O2Te continuous films are demonstrated. Noticeably, except for an ultrahigh mobility (∼45074 cm2 V-1 s-1 at 2 K) and obvious Shubnikov-de Hass quantum oscillations, a 2D transport channel and large linear magnetoresistance are revealed in the patterned Bi2O2Te films. Investigation implies that the linear magnetoresistance correlates with the inhomogeneity described by P. B. Littlewood's theory and EMT-RRN theory developed recently. These results not only reveal the nonsaturating linear magnetoresistance in high-quality Bi2O2Te but shed light on understanding the corresponding physical origin of linear magnetoresistance in 2D high-mobility semiconductors and providing a pathway for the potential application in multifunctional electronic devices.

Introduction to microelectronic design in a distance learning program

This paper describes observations and experiences collected during 14 years of running the “Integrated circuits” course in the framework of a distance learning program. The main objective of the “Integrated circuits” course is to raise the interest in microelectronics, convince the students that IC design is not a “secret science” requiring extraordinary talent and prepare the students for continuation toward M.Sc. degree. The course includes a mixture of teaching materials available online for self-studying, short video files, interactive self-tests, two “hands on” exercises and educational software needed for these exercises. E-mail and/or phone consultations, face-to-face or online meetings with the instructor are possible. About 1/3 of all students enrolled for the distance learning course perceive the “Integrated circuits” course as interesting, praise the design exercises and ask if it would be possible to continue education in microelectronic design at a more advanced level. Unfortunately distance learning at advanced level is not possible, mainly because professional design software can be used only on site, not remotely.

A New Alternative Electrochemical Process for a Pre-Deposited UPD-Mn Mediated the Growth of Cu(Mn) Film by Controlling the Time during the Cu-SLRR

A layer-by-layer deposition is essential for fabricating the Cu interconnects in a nanoscale-sized microelectronics because the gap-filling capability limits the film deposition step coverage on trenches/vias. Conventional layer-by-layer electrochemical deposition of Cu typically works by using two electrolytes, i.e., a sacrificial Pb electrolyte and a Cu electrolyte. However, the use of a Pb electrolyte is known to cause environmental issues. This study presents an Mn monolayer, which mediated the electrochemical growth of Cu(Mn) film through a sequence of alternating an underpotential deposition (UPD) of Mn, replacing the conventionally used UPD-Pb, with a surface-limited redox replacement (SLRR) of Cu. The use of the sacrificial Mn monolayer uniquely provides redox replacement by Cu2+ owing to the standard reductive potential differences. Repeating the sequence of the UPD-Mn followed by the SLRR-Cu enables Cu(Mn) film growth in an atomic layer growth manner. Further, controlling the time of open circuit potential (OCP) during the Cu-SLRR yields a technique to control the content of the resultant Cu(Mn) film. A longer OCP time caused more replacement of the UPD-Mn by the Cu2+, thus resulting in a Cu(Mn) film with a higher Cu concentration. The proposed layer-by-layer growth method offers a wet, chemistry-based deposition capable of fabricating Cu interconnects without the use of the barrier layer and can be of interest in microelectronics.

Atomic layer deposition of BN as a novel capping barrier for B2O3

The deposition of boron oxide (B2O3) films on Si and SiO2 substrates by atomic layer deposition (ALD) is of growing interest in microelectronics for shallow doping of high aspect ratio transistor structures. B2O3, however, forms volatile boric acid (H3BO3) upon ambient exposure, requiring a passivation barrier, for which BN was investigated as a possible candidate. Here, the authors demonstrate in situ deposition of BN by sequential BCl3/NH3 reactions at 600 K on two different oxidized boron substrates: (a) B2O3 deposited using BCl3/H2O ALD on Si at 300 K (“B2O3/Si”) and (b) a boron-silicon oxide formed by sequential BCl3/O2 reactions at 650 K on SiO2 followed by annealing to 1000 K (“B-Si-oxide”). X-ray photoelectron spectroscopy (XPS) data demonstrate layer-by-layer growth of BN on B2O3/Si with an average growth rate of ∼1.4 Å/cycle, accompanied by some B2O3 removal during the first BN cycle. In contrast, continuous BN growth was observed on B-Si-oxide without any reaction with the substrate. XPS data also indicate that the oxide/nitride heterostructures are stable upon annealing in ultrahigh vacuum to >1000 K. XPS data, after the exposure of these heterostructures to ambient, indicate a small amount of BN oxidation at the surface NHx species, with no observable hydroxylation of the underlying oxide films. These results demonstrate that BN films, as thin as 13 Å, are potential candidates for passivating boron oxide films prepared for shallow doping applications.

Thermodynamic and Electrophysical Properties of Nanosized LaMeFeCrMnO6.5 (Me = Li, Na, K) Ferro-Chromo-Manganites

Ferro-chromo-manganites with compositions LaMeFeCrMnO6.5 (Me = Li, Na, K) are synthesized via ceramic technology from La2O3 (special purity grade), Fe2O3, Cr2O3, Mn2O3, and carbonates of alkali metals (analytical grade). The individuality of the resulting compounds is confirmed via X-ray phase analysis. The heat capacity of nanosized LaMeFeCrMnO6.5 (Me = Li, Na, K) ferro-chromo-manganites is measured via dynamic calorimetry in the temperature interval of 298.15–673 K on an IT-S-400 apparatus. The values of C°p(T) and thermodynamic functions H°(T)–H°(298.15), S°(T), and Φ xx (T) are calculated. The temperature dependences of the electrical capacity (C), dielectric permeability (e) and electrical resistivity (R) studied in the temperature range of 293–483 K show that these materials are also of interest for microelectronics.

Origami by frontal photopolymerization.

Origami structures are of great interest in microelectronics, soft actuators, mechanical metamaterials, and biomedical devices. Current methods of fabricating origami structures still have several limitations, such as complex material systems or tedious processing steps. We present a simple approach for creating three-dimensional (3D) origami structures by the frontal photopolymerization method, which can be easily implemented by using a commercial projector. The concept of our method is based on the volume shrinkage during photopolymerization. By adding photoabsorbers into the polymer resin, an attenuated light field is created and leads to a nonuniform curing along the thickness direction. The layer directly exposed to light cures faster than the next layer; this nonuniform curing degree leads to nonuniform curing-induced volume shrinkage. This further introduces a nonuniform stress field, which drives the film to bend toward the newly formed side. The degree of bending can be controlled by adjusting the gray scale and the irradiation time, an easy approach for creating origami structures. The behavior is examined both experimentally and theoretically. Two methods are also proposed to create different types of 3D origami structures.

Low-cost and versatile thermal test chip for power assemblies assessment and thermometric calibration purposes

Abstract Chips specifically designed for thermal tests such as the assessment of packages, are of main interest in Microelectronics. Nevertheless, these test dies are required in relatively low quantities and their price is a limiting factor. This work describes a low-cost thermal test chip, specifically developed for the needs of power electronics. It is based on a poly-silicon heating resistor and a decoupled Pt temperature sensing resistor on the top, allowing to dissipate more than 60 W (170 W/cm2) and reaching temperatures up to 200 °C. Its simple structure allows an easy simulation and modeling. These features have been taken in profit for packaging materials assessment, calibration of temperature measurement apparatus and methods, and validation of thermal models and simulations.

Phase Transformations of the Magnetic Structure in Film Nanobridges

The magnetic structure of a plane nanobridge consisting of two ferromagnetic film electrodes connected by a nanosized crossbar of the same material is studied. Due to their magnetoresistive properties, such bridges are of considerable interest for microelectronics. Using a numerical micromagnetics method, it is shown that a domain wall is displaced from the center of the bridge crossbar as the anisotropy constant of the system decreases and reaches a critical value. A phase diagram is constructed, which makes it possible to determine the possible magnetic states of real nanobridges. The mechanism of the phase transformation is described in terms of an analytical model. This model explains the shape of the phase diagram of the nanobridge. Formally, the transformations of the magnetic structure of the nanocontact can be described in terms of the Landau theory of phase transitions in a certain range of parameters of the system.

Making Nanoscale Materials with Supercritical Fluids

Supercritical Carbon Dioxide Extraction-Mediated Amendment of a Manganese Oxide Surface Desired to Selectively Transform Nitrogen Oxides and/or Ammonia,

Ultra-short pulsed laser ablation of polymers

We report the experimental results of the ablation rate per pulse as a function of the laser fluence and images of the surface morphology, as examined by atomic force microscopy, for a number of organic polymer materials of special interest in microelectronics and biomedical applications. The ablation parameters and the surface modifications are examined under various irradiation conditions using laser wavelengths ranging from the ultraviolet through the visible to the infrared and pulse widths ranging from nanoseconds to femtoseconds. Our results are discussed in the view of interplay between the material properties and the radiation dependent parameters governing the ablation process. Visible and infrared ultra-short pulsed laser ablation of the polymer samples was performed with a very low threshold fluence of approximately 0.2 mJ/mm 2. The irradiated polymers exhibit different optical transmission properties in the corresponding spectral regions. The quantitative results on ablation rate versus laser energy fluence show that the picosecond laser ablation is more efficient than the sub-picosecond and nanosecond ablation, i.e., it exhibits higher etch rates before the onset of any saturation.

Luminescence of Europium–Doped Anodic Oxide Films on Multilayer Titanium–Tantalum Composites

Luminescence of europium in anodic oxide films on thin–film Ti–Ta composites and the process of anodic oxidation of these by the method of chronovoltammetry are investigated for different orders of arrangement of metallic layers and temperatures of heat treatment. A correlation between the luminescence spectra and chronovoltammetric diagrams is noted. The luminescence is shown to be an efficient method for studying the complex phase composition of anodic oxide films. The luminescence spectra of samples are characterized by the presence of several types of luminescence centers inherent in the Eu3+ ion and the base. Conditions for the formation of Eu–doped anodic oxide films on a diffusion alloy, which are of interest for microelectronics as a new dielectric material, are determined.

Surface analysis in microelectronics.

The contribution given by surface analysis to solve some problems encountered in the production of electronic power devices have been discussed. Mainly two types of problems have been faced. One of these deal with interfacial chemistry. Three examples have been investigated. The first applies to the improvement of the quality and the reliability of plastic packages through the optimization of the resin/metal and resin/die adhesion. The second relies to the adhesion between polyimide and silicon nitride used in the multilevel technology. The third example refers to the so called die-attach process and related problems. Another area of interest in microelectronics is that of the erosion of various types of surfaces and the possibility of wrong etching. A few examples of the application of surface analytical techniques for these problems will be presented. XPS and SIMS working in imaging and multipoint analysis mode, scanning acoustic microscopy, contact angle measurements as well as peeling and tensile strength measurements are the main tools used to obtain useful data.

Evolution of atomic-scale surface structures during ion bombardment: A fractal simulation

Surfaces of interest in microelectronics have been shown to exhibit fractal topographies on the atomic scale. A model utilizing self-similar fractals to simulate surface roughness has been added to the ion bombardment code trim. The model has successfully predicted experimental sputtering yields of low energy (less then 1000 eV) Ar on Si and D on C using experimentally determined fractal dimensions. Under ion bombardment the fractal surface structures evolve as the atoms in the collision cascade are displaced or sputtered. These atoms have been tracked and the evolution of the surface in steps of one monolayer of flux has been determined. The Ar–Si system has been studied for incidence energies of 100 and 500 eV, and incidence angles of 0°, 30°, and 60°. As expected, normally incident ion bombardment tends to reduce the roughness of the surface, whereas large angle ion bombardment increases the degree of surface roughness. Of particular interest though, the surfaces are still locally self-similar fractals after ion bombardment and a steady state fractal dimension is reached, except at large angles of incidence.

UV-Laser Photoablation Of Thermostable Polymers: Polyimides, Polyphenylquinoxaline and Teflon AF

ABSTRACTThe UV laser ablation of three thermostable polymers, polyimide, polyphenylquinoxaline and Teflon AF of interest for microelectronics is presented. Direct absorption of the laser beam is not possible by Teflon, but a doping technique is described.

The growing use of electron beams for processing in microelectronics

Four original papers are assembled in this issue to highlight the work which is being carried out on the use of electron beams in microelectronics. A brief background description is given of the phenomena which are of interest for microelectronics. This is followed by short descriptions of the scanning electron microscope and an electron projection system. Various features of the original papers are tied in with the background material.