Edmund P. Burte

An improvement of defected ground structure lowpass/bandpass filters using H-slot resonators and coupling matrix method

A novel compact wideband high-rejection lowpass filter (LPF) using H-DGS is presented. The proposed filter has neither open stub nor cascaded high-low impedance elements. It consists of two coupled H-slots in the ground plane along with a compensated line. The effect of the new slot on the filter performance is examined. The comparison with the conventional filters shows that the proposed one guarantees a large rejected-band of 20dB from 2.5 to 16 GHz. Experimental measurements by means of HP8719D network analyzer agree well with simulated results which are carried out by Microwave Office. Based on H-DGS LPF Structure, a novel bandpass filter (BPF) will be is designed and tested verified by using both J-inverter and coupling matrix methods.

Design of H-shaped low actuation-voltage RF-MEMS switches

Low actuation-voltage and high reliable microelectromechanical systems (MEMS) shunt capacitive and shunt resistive switches are in this paper proposed. Electrostatic-mechanical coupling using finite element method (FEM) and full-wave electromagnetic (EM) analyses have been performed. The mechanical design of a low spring-constant switch structure has been optimized by calculating the dependence of the actuation voltage on the membrane shape, material properties and geometrical sizes. The proposed switches, based on Al metallization membrane, show a pull-in voltage around 7 and 13 Volts with 0 and 20 MPa residual stresses, respectively. The simulated insertion losses are less than 0.25 dB up to 40GHz with a return loss of about 20 dB in the ON- state. The isolations in the OFF-state for the capacitive-switch are greater than 20 and 35 dB at 12 and 40 GHz, respectively. The shunt resistive switch theoretically works from zero frequency with isolation greater than 25 dB up to 40 GHz. The fabrication of those switches is compatible with standard CMOS technology and they are in process.

Electrical properties of thin reoxidized dual-layer oxides

Abstract A dual-layer silicon oxide consisting of reoxidized low-pressure thermal oxide and chemically vapour deposited high temperature oxide at a low pressure prepared by an intra-chamber process is introduced. In this paper, electrical properties of these stacked oxide films are studied. They exhibit higher breakdown field strengths, better charge-to-breakdown characteristics as well as lower defect densities than conventional thermal oxides. Furthermore they reveal low interface state densities and good interface stability under constant current stress. Applying the Fowler-Nordheim tunnelling experiments, the barrier heights between the silicon substrate and the low-pressure oxide and between the metallization and the high-temperature oxide was determined to be 2.8±0.1 eV and 2.6±0.1 eV respectively.

Ag films grown by remote plasma enhanced atomic layer deposition on different substrates

Silver (Ag) layers were deposited by remote plasma enhanced atomic layer deposition (PALD) using Ag(fod)(PEt3) (fod = 2,2-dimethyl-6,6,7,7,8,8,8-heptafluorooctane-3,5-dionato) as precursor and hydrogen plasma on silicon substrate covered with thin films of SiO2, TiN, Ti/TiN, Co, Ni, and W at different deposition temperatures from 70  to 200 °C. The deposited silver films were analyzed by x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) with energy dispersive x-ray spectroscopy, four point probe measurement, ellipsometric measurement, x-ray fluorescence (XRF), and x-ray diffraction (XRD). XPS revealed pure Ag with carbon and oxygen contamination close to the detection limit after 30 s argon sputtering for depositions made at 120 and 200 °C substrate temperatures. However, an oxygen contamination was detected in the Ag film deposited at 70 °C after 12 s argon sputtering. A resistivity of 5.7 × 10−6 Ω cm was obta...

Fabrication and investigation of three-dimensional ferroelectric capacitors for the application of FeRAM

Ferroelectric capacitors made by lead zirconate titanate (PZT) thin films and iridium electrodes are fabricated on three-dimensional structures and their properties are investigated. The iridium films are grown by Plasma Enhanced MOCVD at 300°C, while the PZT films are deposited by thermal MOCVD at different process temperatures between 450°C and 550°C. The step coverage and composition uniformity of the PZT films on trench holes and lines are investigated. Phase separation of PZT films has been observed on both 3D and planar structures. No clear dependences of the crystallization and composition of PZT on 3D structure topography have been found. STEM EDX line scans show a uniform Zr/(Zr+Ti) concentration ratio along the 3D profile but the variation of the Pb/(Zr+Ti) concentration ratio is large because of the phase separation. 3D ferroelectric capacitors show good ferroelectric properties but have much higher leakage currents than 2D ferroelectric capacitors. Nevertheless, during cycling tests the degrad...

Hot Wire Chemical Vapor Deposition of Ge2Sb2Te5 Thin Films

Germanium-antimony-telluride or, particularly, Ge 2 Sb 2 Te 5 (GST) thin films were deposited by hot wire (HW) chemical vapor deposition (CVD). Tetraallylgermanium, triisopropylantimony, and diisopropyltelluride were used as precursors for germanium, antimony, and tellurium, respectively. The influence of deposition parameters, such as temperature, pressure, and hydrogen content, was investigated. It was found that higher temperature, higher pressure, and lower hydrogen flow yielded higher growth rates of the films. An admixture of hydrogen reduced the Te concentration in the GST thin films and enhanced the content of Ge and Sb. The chemical composition could also be altered by other deposition parameters but these dependencies were not as well pronounced as in the hydrogen case. Generally, a higher Ge concentration was related to a smaller amount of Te. The films deposited at a higher pressure showed a significantly higher roughness. In addition, the switching from a low to high resistivity state was tested.

Control of Bandwidth and Resonant Frequency of a New Coplanar Bandpass Filter

This paper presents the design of a new compact end-coupled bandpass filter (BPF). This structure is based on coplanar waveguide (CPW) lines and lambda/4 resonators. Both the bandwidth and the matching can be easily controlled by changing the dimensions of the components of the filter. The structure has been implemented for the bands 2.5-7.6 GHz and 1.7-5.2 GHz. The electromagnetic and equivalent-circuit simulations are in good agreement with the measurements.

Characterization of Oxide Etching and Wafer Cleaning using Vapor-Phase Anhydrous HF and Ozone

A cleaning process using anhydrous HF (AHF)/methanol and ozone is carried out in a STEAG-AST Vapor Phase Cleaning module (VPC). This module is integrated in a state-of-the-art cluster tool also consisting of a STEAG-AST Rapid Thermal Oxidation module (RTO). The dependence of AHF vapor phase etch rate of thermally grown silicon dioxide on different process parameters, such as etch time, AHF-flow, and temperature is evaluated. The optimized etch process is found to be at a temperature of 40°C and at a pressure of 50 mbar for this VPC module. Using the above etch parameters various combinations of vapor phase surface preparation chemistries combining AHF etching and ozone/UV cleaning are evaluated. To demonstrate the feasibility of this cluster tool for advanced gate dielectric formation, 4.0 nm thin oxide is grown directly after the cleaning in the RTO module without breaking the vacuum. Time dependent dielectric breakdown results for oxides pre-oxidation-cleaned in AHF, and in AHF followed by ozone are compared to a reference sample without any dry pre-oxidation cleaning. It can be shown, that the cleaning in AHF with a subsequent ozone step at 200°C under UV light leads to improved breakdown characteristics compared to AHF/methanol cleanings without such subsequent ozone/UV step or conventional wet cleaning using HF-Dip.

Hot wire chemical vapor deposition of germanium selenide thin films for nonvolatile random access memory applications

Thin films of germanium selenide (GexSe100−x with 0<x<57) were deposited on different substrates by hot wire metalorganic chemical vapor deposition using tetraallylgermanium and di-tert-butylselenide. The growth kinetics of the deposition process as well as the properties of the films were investigated. The growth rate was found to decrease with increasing temperature and decreasing pressure. The conformal step coverage was demonstrated. Germanium selenide films covered and subsequently diffused by silver were used as programmable metallization cells for a verification of the electrical switching properties.

A Miniature 3.1 GHz Microstrip Bandpass Filter with Suppression of Spurious Harmonics Using Multilayer Technique and Defected Ground Structure Open-Loop Ring

In this chapter a cascaded bandpass filter composed of three open-loop λ/2 resonators is proposed. The three elements are electromagnetically coupled. They are placed on the top of a multiplayer structure. Electromagnetic simulation of the cascaded bandpass filter shows good results in both passband and in stopbands. The filter provides two 3-dB attenuation pole frequencies f 1 at 2.95 GHz, f 2 at 3.25 GHz, and a center frequency f 0 at 3.1 GHz. In order to develop and to miniaturize this planar three-pole microstrip bandpass filter, two ideas are developed and implemented that are based on DGS technique and the coupling matrix method. Using DGS resonators on the ground structure, a compact filter with improved response has been realized. The proposed filter has been fabricated on a substrate with dimensions of (0.57λ g × 0.28λ g ). The simulated and measured results show good agreement and validate the proposed approach.