用流延法制备优质陶瓷基片的研究

本文概括了流延成型工艺的现状，介绍了有机基流延成型工艺中溶剂及添加剂的作用和选择原则，同时介绍了几种新的流延成型工艺。     

Surface Preparation of Aluminum Nitride for Metallization: Effect of Temperature on Surface Reactivity

The current aqueous cleaning step in the surface preparation of aluminum nitride (AlN) prior to metallization causes performance and reliability issues for the substrates used for microelectronic packaging due to surface reactions. These issues limit the use of AlN and its replacing of BeO, an environmentally hazardous material currently used. The aim of this investigation was to determine the effects of different solutions on the surface of AlN substrates under varying conditions at times up to 2419.2 ks (28 days). Concentration of the solutions, temperature, and immersion time were varied for the AlN samples in the solutions. Both elevated temperatures (50°C and 90°C) and low temperatures (5°C) were investigated.

Four general types of behavior were observed: minor changes in average surface roughness and microstructure, linear change in average surface roughness and pitted grains, nonlinear change in average surface roughness and product formation on AlN surface, and miscellaneous change in average surface roughness with surface product formation.

The surface roughening kinetics were very complex due to changes in both the reaction product morphology and reaction mechanism with temperature, solvent, and pH for a specific solvent. Minor changes in average surface roughness and microstructure were observed for HCl pH = 5, H₂ SO₄ pH = 5, NaOH pH = 8, NaOH pH = 10, NaOH pH = 12, deionized water and Alfred tap water at 5°C, HCl pH = 3 and oleic acid at 50°C and citric acid and oleic acid at 90°C. Linear changes in average surface roughness and pitted grains were observed for HCl pH = 2 and H₂SO₄ pH = 3 at 50°C and HCl pH = 2, H₂SO₄ pH = 3, and deionized water at 90°C. Non-linear change in average surface roughness and product formation on AlN surface was observed for HCl pH = 5, NaOH pH = 8 and Alfred tap water at 50°C and HCl pH = 5 and H₂SO₄ pH = 2 at 90°C. Miscellaneous changes in average surface roughness with surface product formation were observed for H₂SO₄ pH = 2, H₂SO₄ pH = 5, NaOH pH = 10, NaOH pH = 12, citric acid, Micro-90 and deionized water at 50°C and HCl pH = 3, H₂SO₄ pH = 5, NaOH pH = 8, NaOH pH = 10, NaOH pH = 12, Micro-90 and Alfred tap water at 90°C.     

Porous ceramics with tailored pore size and morphology as substrates for coral larval settlement

The growing demand for stony corals as ornamental aquarium animals requires defined aquacultural breeding strategies. For the sexual propagation of corals, material substrates are needed, that attract larvae and support their settlement and development. In this study, five types of highly porous ceramic materials were developed following the example of coral skeleton. The applicability of these settlement substrates was tested using larvae of the stony coral Pocillopora damicornis. Partial sintering of pressed clay pellets, freeze casting of clay and alumina-mullite based slurries and direct foaming of high alkane phase emulsified suspensions (HAPES) using alumina were employed. By the addition of mm-sized spherical polystyrene beads as sacrificial templates during freeze casting (alumina-mullite), superficial pores in the size of the larvae were created. The inorganic substrates featured open porosities between 35% (pressed clay) and 83% (foamed alumina), pore sizes ranging from nm to mm-scale and pore morphologies dominated by interparticle porosity (pressed), lamellar pores (freeze casting) and cellular pore types (direct foaming). The ceramic substrates were incubated in artificial sea water for 3 months to induce necessary biofilm formation and algae growth. Afterwards, individual substrates were exposed to 5 coral larvae, and their settlement behavior was monitored over 14 days. At the end of this period, all ceramic materials were successfully accepted as settlement substrates, with a mean settlement rate of 46.2%, and no significant differences between the substrate types. On samples with large surface superficial pores, a significantly reduced survival of settled larvae (79%) compared to the other porous materials (93–98%) was determined, suggesting a non-ideal surface topography. While alumina foam samples (HAPES) exhibit the most promising results in terms of settlement and survival of larvae, clay-based substrates provide a more economic solution for the sexual propagation of corals in aquaculture.     

Three-Parameter Model for Debonding of FRP Plate from Concrete Substrate

Concrete beams retrofitted with bonded fiber reinforced plastic (FRP) plates often fail by debonding of the plate from the concrete surface. To predict the failure load in design, a proper debonding model is required. As debonding is a nonlinear process involving material softening, it can be analyzed once the interfacial shear (τ) versus sliding (s) relationship is known. Recent experimental results indicate that the simplest τ-s relationship should involve three parameters: the maximum shear stress for debonding to initiate, the initial residual stress right after debonding occurs, and a parameter governing the reduction of shear stress with sliding. In this paper, a FRP debonding model based on these three parameters is developed. The applicability of the model is verified through comparison with experimental results. Through a systematic parametric study, the effect of various material and geometric properties on the debonding process is investigated. Implications to the design of FRP strengthened members are highlighted.     

Relaxation of extrinsic and intrinsic stresses in germanium substrates with silicon films

Si films were deposited on Ge substrates at 400°C by two different Physical Vapor Deposition techniques: (A) ion beam sputtering and (B) magnetron sputtering. The intrinsic stresses in the as-deposited films were measured to be compressive and much greater in samples (A), about −1500 to −2000 MPa than in samples (B), about −300 to −500 MPa. The substrates were subsequently exposed to thermal treatments for varying times at 800°C. In the lower stressed (B) samples, the films had relaxed and reduced the overall curvature of the structure whereas in the high stresses (A) samples, an irreversible large increase in the substrate curvature was found to occur. This indicated that plastic deformation in the Ge substrates itself had occurred.     

Selective LPE-growth of ln0.53Ga0.47As on semi-insulating InP

Selective liquid phase epitaxy (SLPE) of high purity(n = 2 × 10¹⁵ cm^-3) In_0.53Ga_0.47As on SiO₂-masked (100)-InP:Fe substrates has been performed and investigated using Normarski interference contrast microscopy and SEM. The infill growth was done at low temperatures (˜ 585° C) directly into chemically (HC1:CH₃COOH:H₂O₂) etched cavities without melt-etching. Square and circular recesses of 2–3 μm depth and varying size (100-500 μm) have been used in contrast to common reported regrowth experiments in long channels. Enormously enhanced growth rates have been found within the small structures. Orientation dependent growth effects are described. The realization of selectively grown areas with flat surface morphology has been achieved which is important for optoelectronic integration. Most information contained in this paper was presented at the 27th Electronic Materials Conference, Boulder, Co., June 20, 1985.     

On the Growth and Microstructure of Carbon Nanotubes Grown by Thermal Chemical Vapor Deposition

Carbon nanotubes (CNTs) were deposited on various substrates namely untreated silicon and quartz, Fe-deposited silicon and quartz, HF-treated silicon, silicon nitride-deposited silicon, copper foil, and stainless steel mesh using thermal chemical vapor deposition technique. The optimum parameters for the growth and the microstructure of the synthesized CNTs on these substrates are described. The results show that the growth of CNTs is strongly influenced by the substrate used. Vertically aligned multi-walled CNTs were found on quartz, Fe-deposited silicon and quartz, untreated silicon, and on silicon nitride-deposited silicon substrates. On the other hand, spaghetti-type growth was observed on stainless steel mesh, and no CNT growth was observed on HF-treated silicon and copper. Silicon nitride-deposited silicon substrate proved to be a promising substrate for long vertically aligned CNTs of length 110–130 μm. We present a possible growth mechanism for vertically aligned and spaghetti-type growth of CNTs based on these results.     

Effect of the carrier gas on the metal-organic chemical vapor deposition of TiN from tetrakis-dimethyl-amido-titanium

The effect of carrier gas such as hydrogen, nitrogen and argon on the deposition rate, film morphology, resistivity and chemical composition of TiN film from tetrakis-dimethyl-amido-titanium (TDMAT) was studied. The deposition rate was higher with argon and nitrogen and lower with hydrogen when the substrate temperature was above 300°C. The surface morphology of the film deposited with hydrogen carrier gas was rough due to the gas phase reaction. The film deposited at the higher substrate temperature with hydrogen had higher resistivity than in the film deposited with argon or nitrogen due to the rough surface.     

Spreading of polymeric liquids at a microscopic scale

The spreading of polymeric liquids on solid substrates has been a very lively subject of research both by experimentalists and theoreticians. It has been observed that some drops, which spread on solids may form a precursor film of molecular thickness with possible accompanying layers, with a radius growing as a square root of time in the early stages after deposition. These results have been obtained for several polymeric liquids on top of bare or grafted oxidized silicone wafers. The first theoretical model describing this phenomenon was developed by de Gennes and Cazabat. In this original paper the spreading is described as a competition between the driving force, which is due to the wall attraction and the friction between layers of liquid, and the solid. Assuming the essentially viscous nature of the friction forces, the authors were able to recover most of the experimental observations mentioned before. However, the friction parameters have to be introduced at a macroscopic scale and are questionable at a microscopic point of view. It is the aim of this paper to give a review of the experimental observations completed, case by case, by microscopic simulations, giving a more detailed understanding of the rich variety of these phenomena.     

Preparation of c-BN films by RF sputtering and the relation of BN phase formation to the substrate bias and temperature

This paper deals with the deposition of cubic boron nitride (c-BN) films by radio frequency (RF) magnetron sputtering. The nearly pure c-BN films have been prepared on Si(100) substrates using hexagonal boron nitride (h-BN) targets. Argon gas mixed with nitrogen gas was used as sputtering gas. The deposited films were characterized by Fourier transform infrared (FTIR) spectroscopy and transmission electron diffraction (TED). A ‘temperature-bias' phase diagram has been worked out. It indicates that the c-BN phase prefers the relative high temperature and negative bias. An opinion was presented that the c-BN nuclei grow discontinuously with every time the ‘thermal spike' coming.