Device contamination induced by O2 plasma ashing of a photoresist was investigated using a capacitor structure that was fabricated by typical MOS processing. Emphasis was put on the process of ashing the ion-implanted resist and on the subsequent annealing process for the purpose of activating the ion-implanted atoms. It was found that annealing after the ashing process led to contamination of oxides under polysilicon gate films because of the rapid thermal diffusion of the impurities induced in the oxide by ashing. A contamination process model was proposed, and ion microprobe mass analysis showed that the impurities contaminating the gate oxide were sodium and potassium.
Paste-bonding of titanium and Ti- 6 Al- 4V alloy was carried out in the air by using mixtures made up of B4C and Na2B4O7 as the main constituents, NaBF4, NH4Cl and NaCl as the activators and Ca (OH)2 as binder. The influence of paste compositions on boride formation, and the structure, hardness and wear behavior of the boride layers formed onto the metals were investigated. The results obtained are summarized as follows: The most suitable composition of bonding paste for titanium was 65%B4C, 20%Na2B4O7, 8.5%NaBF4, 2.5% (NH4Cl+NaCl) and 4%Ca (OH)2, and that for Ti- 6 Al- 4V was 75%B4C and 10%Na2B4O7, with the other materials in the same proportions as for titanium. Two phases of titanium boride were formed TiB2 on the surface and TiB inside. The TiB2 surface had a hardness of HK (0.196N) 3200-4500. Under identical conditions of formation, the boride layer formed on the titanium was slightly thicker than that on the Ti- 6 Al- 4V alloy, but when the surface roughness of after bonding is taken into account, the Ti- 6 Al- 4V alloy is superior to the titanium as a candidate for bonding. The wear behavior of paste-bonded titanium and Ti- 6 Al- 4V alloy was greatly improved over that of untreated specimens.
A coloring treatment has been applied to SUS 430 and SUS 304 stainless steels by anodizing in 5kmol m-3 NaOH solution. XPS and AES analysis were used to measure the chemical state of the constituents of the color film and composition-depth profiles of the film. Corrosion resistances were estimated by the interfacial impedance method for the stainless steels colored at 298K in 0.1kmol m-3 H2SO4, and at 353K in 20kmol m-3 NaOH. SEM photographs showed some porous surface structures in SUS 430 and SUS 304 polarized at -0.05V for 1h. XPS analysis showed that Cr on the film surface was depleted with increases in polarization time or in applied potential. Films formed on SUS 430 at the transpassive potential (about -0.25V) were Cr-rich and the film became Cr-deficient at more nobler potentials. It can be explained by an increase in the transpassive reaction rate for the Cr component on the surface with increasing applied potential. Since Ni dose not dissolve readily in alkaline solution, its concentration in films on SUS 304 was high. The time during which high interfacial impedance occurred in 298K, 0.1kmol m-3 H2SO4 a and 353K, 20kmol m-3 NaOH solutions increased with increases in polarization time or potential. This is thought to be during to the thicker surface films, giving rise to a higher corrosion resistance for SUS 430 and SUS 304 stainless steels.
Adsorption phenomena of Sn (II) and Pd (II) ions on α-alumina were quantitatively analysed using α-alumina powder. Sn (II) ions adsorbed on α-alumina surface obeying a Fowler-Frumkin type adsorption isotherm, and Pd (II) ions adsorbed on Sn (II) pre-adsorbed α-alumina obeying a Langmuir type isothem. In both cases, Cl- ions played major roles by offering adsorption sites for Sn (II) ions and by controlling stable ionic species of Sn (II) and Pd (II) in the solutions by coordination. The surface states of α-alumina and the ionic species were also affected by the pH of the solutions, resulting in considerable influence on the adsorption phenomena.
It was found that the addition of p-anisaldehyde, polyethyleneglycol (PEG) and formaldehyde (HCHO) to gluconate baths containing SnSO4 and sodium gluconate yielded bright tin deposits. The optimum bath composition and operating conditions for bright tin plating were 0.2M SnSO4, 0.6M sodium gluconate, 0.1g/L p-anisaldehyde, 1g/L PEG (average molecular weight 7500), 0.6mL/L HCHO, pH 5-8, bath temperature 35°C, and current density 10-40mA/cm2. The cathode current efficiency decreased with increasing sodium gluconate concentration and current density. The results of Hull cell tests showed that none of the additives produced any brightening effect on the tin deposit when added singly; bright tin deposits were obtained only when both PEG and HCHO were added to an additive-free bath. The further addition of p-anisaldehyde to baths containing PEG and HCHO yielded bright tin deposits at current densities higher than 20mA/cm2. As the molecular weight of PEG was increased, the bright area of the Hull cell test panel was increased and the current values on cathodic polarization curve were inhibited.
Studies were conducted on the feasibility of particle plating-uniform electroplating on each and every fine particle-as a means of creating new functional composite materials. The following results were obtained; 1) When bed expansion is under 25%, particle plating is feasible from a variety of plating baths. 2) Particle plating proceeds either within 10mm of the cathode, or on the whole of the concentrated suspension layer. 3) There are two patterns of suspension resistance that are conductive to plate on fine particles, and they are determined by one or more of bed expansion of the suspension layer, particle diameter, particle density and plating bath composition.
In electroplating individual fine particles, it is important that the particle suspension layer be stirred homogeneously while being kept at a high concentration. A study was therefore conducted on to determine the most suitable apparatus and appropriate conditions for stirring with a view to improving such powder characteristics as the free-settling ratio and angle of repose in water in particle plating. The results obtained we are as follows; (1)Both tilting and vertical plating apparatus are highly suitable for particle plating. (2)The conditions of particle plating are affected not only by particle diameter but also free-settling ratio and the angle of repose in water, because density, shape, secondary aggregation and so on are different for each type of particle. (3)The tilting angle and rotational speed of tilting apparatus must be properly controlled, and the pitch, size and propeller speed of the vertical type must be suitably adjusted in accordance with the free-settling ratio and angle of repose in water.
The throwing power of Cu (II) -EDTA plating baths containing a large quantity of glycine and potassium chloride, and the physical properties of the films obtained were investigated. The addition of potassium chloride was found to increase the specific conductivity of the baths, resulting in an increase in throwing power. The films obtained were heat-treated for 1h at 160°C resulting in crystal growth and relief of lattice strain, and were shown to have nearly the same elongation and ultimate tensile strength as commercial high ductile electrolytic copper foil.
A study was conducted on copper electrodeposition from Cu (CF3COO)2 (20g/dm3)-MeOH baths, with an additive (LiCl, NH4Cl, AlCl3, LiBr or NH4Br). The LiCl additive inhibited the reduction in anode current efficiency during copper electrodeposition from the bath. The bath with LiCl added yielded bright, smooth copper electrodeposits at a wide range of current densities. The surface of the copper deposits was granular and the cross-section of the deposits was found to have granular structure.
During the past decade electroless plating has been utilized widely for formation of the precise functional films. It is important to investigate the initial deposition processes since the functional characteristics are determined at the early stages of deposition. In this study electroless nickel deposition was measured in-situ by laser beam, and it is concluded that initial deposition comprises a number of characteristic stages. There was found to be an induction period before the plating reaction. Induction time was largely dependent on catalyst adsorption and dissolved oxygen concentration. After this induction time, the initial deposition reaction took place very rapidly at the activated catalytic sites, and the reaction then stagnated and eventually reached steady-state. Transmission electron micrographs show that initially the nickel grew laterally followed by steady-state growth, and the plating reaction proceeded three dimensionally.