Origin of high oxide to nitride polishing selectivity of ceria-based slurry in the presence of picolinic acid

We report on the investigation of the origin of high oxide to nitride polishing selectivity of ceria-based slurry in the presence of picolinic acid. The oxide to nitride removal selectivity of the ceria slurry with picolinic acid is as high as 76.6 in the chemical mechanical polishing. By using zeta potential analyzer, particle size analyzer, horizon profilometer, thermogravimetric analysis and Fourier transform infrared spectroscopy, the pre- and the post-polished wafer surfaces as well as the pre- and the post-used ceria-based slurries are compared. Possible mechanism of high oxide to nitride selectivity with using ceria-based slurry with picolinic acid is discussed.

Structural,Morphological and Electrical Properties of In-Doped Zinc Oxide Nanostructure Thin Films Grown on p-Type Gallium Nitride by Simultaneous Radio-Frequency Direct-Current Magnetron Co-Sputtering

Zinc oxide （ZnO） is one of the most promising and frequently used semiconductor materials. In-doped nanos- tructure ZnO thin films are grown on p-type gallium nitride substrates by employing the simultaneous rf and dc magnetron co-sputtering technique. The effect of In-doping on structural, morphological and electrical properties is studied. The different dopant concentrations are accomplished by varying the direct current power of the In target while keeping the fixed radio frequency power of the ZnO target through the co-sputtering deposition technique by using argon as the sputtering gas at ambient temperature. The structural analysis confirms that all the grown thin films preferentially orientate along the c-axis with the wurtzite hexagonal crystal structure without having any kind of In oxide phases. The presenting Zn, 0 and In elements＇ chemical compositions are identified with EDX mapping analysis of the deposited thin films and the calculated M ratio has been found to decrease with the increasing In power. The surface topographies of the grown thin films are examined with the atomic force microscope technique. The obtained results reveal that the grown film roughness increases with the In power. The Hall measurements ascertain that all the grown films have n-type conductivity and also the other electrical parameters such as resistivity,mobility and carrier concentration are analyzed.

Boron nitride microribbons strengthened and toughened alumina composite ceramics with excellent mechanical,dielectric,and thermal conductivity properties

Aluminum oxide(Al_(2)O_(3))ceramics have been widely utilized as circuit substrates owing to their exceptional performance.In this study,boron nitride microribbon(BNMR)/Al_(2)O_(3)composite ceramics are prepared using spark plasma sintering(SPS).This study examines the effect of varying the amount of toughened phase BNMR on the density,mechanical properties,dielectric constant,and thermal conductivity of BNMR/Al_(2)O_(3)composite ceramics while also exploring the mechanisms behind the toughening and increased thermal conductivity of the fabricated ceramics.The results showed that for a BNMR content of 5 wt%,BNMR/Al_(2)O_(3)composite ceramics displayed more enhanced characteristics than pure Al_(2)O_(3)ceramics.In particular,the relative density,hardness,fracture toughness,and bending strength were 99.95%±0.025%,34.11±1.5 GPa,5.42±0.21 MPa·m^(1/2),and 375±2.5 MPa,respectively.These values represent increases of 0.76%,70%,35%,and 25%,respectively,compared with the corresponding values for pure Al_(2)O_(3)ceramics.Furthermore,during the SPS process,BNMRs are subjected to high temperatures and pressures,resulting in the bending and deformation of the Al_(2)O_(3)matrix;this leads to the formation of special thermal pathways within it.The dielectric constant of the composite ceramics decreased by 25.6%,whereas the thermal conductivity increased by 45.6%compared with that of the pure Al_(2)O_(3)ceramics.The results of this study provide valuable insights into ways of enhancing the performance of Al_(2)O_(3)-based ceramic substrates by incorporating novel BNMRs as a second phase.These improvements are significant for potential applications in circuit substrates and related fields that require high-performance materials with improved mechanical properties and thermal conductivities.

High Performance 70nm CMOS Devices

A high performance 70nm CMOS device has been demonstrated for the first time in the continent, China. Some innovations in techniques are applied to restrain the short channel effect and improve the driving ability, such as 3nm nitrided oxide, dual poly Si gate electrode, novel super steep retrograde channel doping by heavy ion implantation, ultra shallow S/D extension formed by Ge PAI(Pre Amorphism Implantation) plus LEI(Low Energy Implantation), thin and low resistance Ti SALICIDE by Ge PAI and special cleaning, etc. The shortest channel length of the CMOS device is 70nm. The threshold voltages, G m and off current are 0 28V,490mS·mm -1 and 0 08nA/μm for NMOS and -0 3V,340mS·mm -1 and 0 2nA/μm for PMOS, respectively. Delays of 23 5ps/stage at 1 5V, 17 5ps/stage at 2 0V and 12 5ps/stage at 3V are achieved in the 57 stage unloaded 100nm CMOS ring oscillator circuits.

Review on Enhancement of Nitridation of Si Powder

This paper reviewed the effect of powder characteristics and additives including metals,rare earth oxides,and ZrO2 on nitridation of Si powder.The decrease of particle size of Si powder increased nitridation.Most of metal additives inhibited nitridation,while some metal additives such as Fe,Cu,Cr,and Ca increased nitrida—tion.Otherwise,the addition of metals might lead to the degradation of physical and mechanical properties of Si3N4.All the rare earth oxides,especially CeO2 and Eu2O3,showed nitridation enhancing effect.In addition,ZrO2 with small particle size showed a stronger enhancing effect.

V_(2)O_(3)/VN electrocatalysts with coherent heterogeneous interfaces for selecting low-energy nitrogen reduction pathways

Electrochemical nitrogen reduction reaction(NRR)is a sustainable alterna-tive to the Haber-Bosch process for ammonia(NH3)production.However,the significant uphill energy in the multistep NRR pathway is a bottleneck for favorable serial reactions.To overcome this challenge,we designed a vanadium oxide/nitride(V_(2)O_(3)/VN)hybrid electrocatalyst in which V_(2)O_(3)and VN coex-ist coherently at the heterogeneous interface.Since single-phase V_(2)O_(3)and VN exhibit different surface catalytic kinetics for NRR,the V_(2)O_(3)/VN hybrid elec-trocatalyst can provide alternating reaction pathways,selecting a lower energy pathway for each material in the serial NRR pathway.As a result,the ammo-nia yield of the V_(2)O_(3)/VN hybrid electrocatalyst was 219.6µg h^(-1)cm^(-2),and the Faradaic efficiency was 18.9%,which is much higher than that of single-phase VN,V_(2)O_(3),and VNxOy solid solution catalysts without heterointerfaces.Density functional theory calculations confirmed that the composition of these hybrid electrocatalysts allows NRR to proceed from a multistep reduction reaction to a low-energy reaction pathway through the migration and adsorption of interme-diate species.Therefore,the design of metal oxide/nitride hybrids with coherent heterointerfaces provides a novel strategy for synthesizing highly efficient elec-trochemical catalysts that induce steps favorable for the efficient low-energy progression of NRR.

Effects of Nitridation Temperature on Characteristics of Gallium Nitride Thin Films Prepared Via Two-Step Method

In this research,the growth of GaN thin films on c-plane sapphire（0001） substrates via two-step method without the assist of buffer layer and catalysts was demonstrated.First,gallium oxide（Ga_2O_3） thin films were deposited on sapphire substrates by radio frequency magnetron sputtering method.The deposited Ga_2O_3 thin films were then nitridated at various temperatures.In this research,attention is focused on the influence of nitridation temperatures on the structural and optical properties of the synthesized GaN thin films.It is revealed that 950 ℃ is the optimal nitridation temperature for synthesizing hexagonal wurtzite GaN thin film with preferential（0002） growth direction.

Plasma electrolytic oxidation of the magnesium alloy MA8 in electrolytes containing TiN nanoparticles

The formation of protective multifunctional coatings on magnesium alloy MA8 using plasma electrolyt- ic oxidation （PEO） in an electrolytic system containing nanosized particles of titanium nitride was investigated. Electrochemical and mechanical properties of the obtained layers were examined. It was established that microhardness of the coating with the nanoparticle concentration of 3 gl-1 increased twofold （4.2 ± 0.5 GPa）, while wear resistance decreased （4.97 × 10-6 mm3 N-1 m-1）, as compared to re- spective values for the PEO-coating formed in the electrolyte without nanoparticles （2.1 ± 0.3 GPa, 1.12 × 10.5 mm3 N-1 m-1）.