Yuh Sung

Preparation and properties of a graphene reinforced nanocomposite conducting plate

This study presents a novel nanocomposite conducting plate (CP) reinforced by graphene at a low weight fraction percentage, and compares the properties of this novel nanocomposite CP with those containing various weight fractions of multi-wall carbon nanotubes (MWCNT) (0.2, 0.5, and 1 phr). Adding only 0.2 phr of graphene as reinforcement remarkably enhanced the thermal, mechanical, and electrical properties of the nanocomposite CP. The coefficient of thermal expansion (CTE) of nanocomposite CP below the glass transition temperature (Tg) decreased from 49.7 μm−1 m °C−1 to 26.9 μm−1 m °C−1 and the CTE above Tg decreased from 119.2 μm−1 m°C−1 to 55.2 μm−1 m °C−1. Thermal conductivity increased from 18.4 W m−1 K−1 to 27.2 W m−1 K−1. The flexural strength increased from to 28.0 MPa to 49.2 MPa. The in-plane electrical conductivity increased from 155.7 S cm−1 to 286.4 S cm−1. The enhancement percentages of these properties are 47.8%, 75.7%, and 83.9%, respectively, which are much higher than that of the original composite CP. These results indicate that using graphene as reinforcement in the preparation of nanocomposite CP is effective in terms of cost and performance, because of the low cost the raw material, graphite, and the fact that a lower loading of graphene than of MWCNT can yield the same performance. Moreover, this novel multi-functional nanocomposite CP has wide potential for use in proton exchange membrane fuel cells (PEMFCs), direct methanol fuel cells (DMFCs), the dye-sensitized solar cells (DSSCs) counter electrode, and vanadium redox battery (VRB) applications.

A method to fabricate field emitters using electroless codeposited composite of MWNTs and nickel

A method to fabricate good carbon nanotube (CNT) field emitters using electroless codeposition and CNT purification techniques was developed. Multiwalled CNTs (MWNTs) were codeposited with Ni to form a composite layer acting as the emitter. This composite layer is uniform in thickness and the MWNTs distributed in Ni matrix show a strong adhesion to the substrate. To ensure the emitting quality and good dispersion of MWNTs in the composite, heat annealing and acid immersion process were employed. The composite film shows good emission uniformity and the current density of 1.0 mA/cm 2 was obtained at about 5.7 V/μm.

Effects of Molybdate Concentration on the Characteristics of Ni – Mo – P Diffusion Barriers Grown by Nonisothermal Electroless Deposition

Ternary Ni-based amorphous films can serve as a barrier layer for Cu interconnects in ultralarge-scale integration (ULSI) applications. In this paper, Ni-Mo-P films deposited on silicon wafers without a complicated pretreatment such as Pd activation were prepared using a nonisothermal deposition (NITD) method. The deposition solutions and operating conditions for preparing the Ni-Mo-P alloys are presented, and the effect of the concentration of MoO 2- 4 added in electrolytes on the deposition rate is investigated. The surface morphology, microstructures, compositions, and electrical resistivity of the Ni-Mo-P deposits are also thoroughly examined. Based on the experimental results, the Ni-based ternary alloys produced by the NITD method contain high levels of both Mo and P, and the properties of Ni-Mo-P films are dependent on the concentration of molybdate in electrolytes. It is concluded that the Ni-Mo-P thin films produced by the proposed approach in this study are promising for the 60 nm technologies in ULSI.

Ultrathin Ni–Mo–P Diffusion Barriers Deposited Using Nonisothermal Deposition Method in Acid Bath

The performance and thermal stability of the ultrathin nickel-molybdenum-phosphorus (Ni-Mo-P) barrier layer deposited by the nonisothermal deposition method in acid electroless bath have been clearly investigated. The as-deposited Ni-Mo-P film (15 nm) has a low resistivity, contains high amounts of Mo (6.7 atom %) and P (25 atom %), and has an amorphous structure. The barrier capability of this Ni-Mo-P film remains stable up to 650°C for 1 h annealing. This reveals that the resistance of Ni-Mo-P barrier film against Cu diffusion is very prominent, and this method for depositing Ni-Mo-P films is extremely promising for ultralargescale integration application.

Defect-Free Copper Filling Using Nonisothermal Electroless Deposition with Fluorocarbon Surfactant

Electroless copper bottom-up filling of patterned substrates using nonisothermal deposition (NITD) with the addition of adequate surfactant was demonstrated. Combining the inhibitive ability of adequate surfactant with the higher driving force of NITD method, superfill of vias or trenches using only one inhibitor in the copper damascene of integrated circuits (ICs) was achieved. We tested several commercial surfactant agents and found that fluorinated alkyl quaternary ammonium iodides (FC) is best compatible to our NITD method. Void-free copper-filled features can be obtained by introducing the surfactant FC into the electroless bath of NITD. Furthermore, using our method, the conductivity of copper film was not negatively affected. We conclude that the surfactant FC combined with NITD method is very promising for the applications in filling trenches and vias with copper films in the IC industry.