Mechanochemical Polishing Research Articles

フェライト材のメカノケミカルポリシング Ｉ 加工液，定盤材質及び加工機構について

This paper presents some experimental results on mechano-chemical polishing of ferrite, and suggestion on the mechanism of mechano-chemical polishing. Such elastic polishing plates as synthetic leather is popularly used with an alkaline polishing fluid in the mechano-chemical polishing of semiconductive materials. In this paper, however, polishing plates made by either tin or lead are used with chemically active polishing fluid to ferrite. Electro-chemical action is added to mechanical polishing for the sake of composing the local cell between a polishing plate and a workpiece. Electro-chemical action not only increases stock removal rate twice or more, but also reduces the surface damaged layer of workpieces a quarter or less in comparison with those in mechanical polishing process.

A deep level transient spectroscopy analysis of electron and hole traps in bulk-grown GaAs

The electron and hole traps occurring in melt-grown undoped n-type GaAs have been studied using deep level transient spectroscopy. Several electron traps with energies ranging from 0.81 to 0.14 eV below the conduction band, as well as three hole traps having energies 0.65, 0.56, and 0.43 eV above the valence band, were measured. Isochronal annealing in the temperature range 500–800 °C indicated that, under optimized ‘‘face-to-face’’ annealing conditions, an 800 °C heat treatment for 1 h resulted in the removal of all the electron traps, with the exception of the EL2 (0.81 eV). Near the surface, however, this annealing procedure reduced the EL2 concentration by more than an order of magnitude. It was further observed that, when a sample is annealed ‘‘face-to-face’’ with another sample, the total defect concentration is reduced much more than when a sample is covered with graphite as during a standard liquid-phase epitaxy (LPE) pregrowth anneal cycle at the same temperature. The effect of surface damage during mechanochemical polishing on defect concentration has also been demonstrated.

Characterization of mechanochemically polished (111) surface of silicon crystal by diffuse x-ray scattering

Diffuse x-ray scattering technique was applied to characterize the surface of a (111) silicon wafer polished mechanochemically. Extra diffuse scattering, which is considered to be attributable to localized strain fields, was detected. The localized lattice distortions were of similar characteristics to those found in a (111) surface lapped with white alundum (No. 2000) and etched by 30∼60 μm [S. Yasuami and J. Harada, J. Appl. Phys. 52, 3989 (1981)]. The thickness of the damaged layer induced by mechanochemical polishing was only about 15 μm, however, which is much smaller than that obtained by lapping (about 100 μm). This is the first observation of the damage left in a mechanochemically polished (111) silicon surface.

ChemInform Abstract: MECHANOCHEMICAL POLISHING OF SILICON NITRIDE

AbstractFe2O3 und Fe3O4 erweisen sich als geeignete milde Schleifmittel für das mechanochemische Polieren von Si3N4.

Mechanochemical Polishing of Silicon Nitride

Two oxides of iron, Fe2O3 and Fe3O4, were identified as suitable soft abrasives for mechanochemical polishing of Si3N4. Removal rates up to 1.6 μ.m /h were observed when hot‐pressed Si3N4 samples were mechanochemically polished using these abrasives on a linen plastic lap. The polished surfaces were flat and scratch‐free, with a peak‐to‐valley roughness of <20 nm. Auger electron spectroscopy of these surfaces revealed a thin layer (≤10 nm) of a silicon oxynitride that contained carbon and ∼0.5 at.% iron.

Ｓｉ単結晶のメカノケミカルポリシングにおける加工速度促進機構 メカノケミカルポリシングの研究 ＩＩ

Mechano-chemical polishing characteristics of Si single crystals are studied by changing the tem-perature of polisher surface and reagent, and “apparent” activation energies of Si in polishing are obtained from Arrhenius plots of polishing rate. It is confirmed that the activation energy of work surface is apparently reduced. Mutual relation be-tween the reduction share considered as thermal energy E and frictional calorific value Q obtained from polishing forces are investigated. Results ob-tained are as follows : (1) Mechano-chemical polish-ing rate increases exponentially as the polisher surface temperature increases. Arrhenius plots of the polishing rate at each temperature agree well with the linear law. The thermal energy E increases as polishing pressure or abrasives concentration increases. (2) The functional relation between frictional calorific value Q (kcal/h) and thermal energy E (kcal/h), is expressed approximately as E=αQ-β (α, β; constant, E≥0). α in mechano-chemical polish-ing (=1/13-1/21) is 1 figure larger than that in disc type chemical polishing (=1/300) without abrasives. In each polishing condition, E is equal to zero when Q is less than 750 × 10-4 (kcal/h). (3) Increase in polishing surface temperature, that facilitates chemical reaction with a polishing reagent in mechano-chemical polishing, is due to frictional heat. The friction effect between work and abrasives on the polishing rate increase is larger than that between work and polisher.

Schottky barrier height and reverse current of the n-Si-electrolyte junction

We present a new set of results on the current-voltage and capacitance-voltage characteristics of the n-Si-aqueous electrolyte interface. The extreme sensitivity of these characteristics to surface defects has been realized, and defect-free surfaces have been obtained by using a mechanochemical polishing method. A transient technique has allowed us to measure the anodic current density for the oxide-free surface. We have performed these experiments for samples of various donor concentrations and electrolytes of various pH. In each case the flat-band potential and Schottky barrier height have been obtained. The results show that the process for anodic current is thermally activated electron transfer from surface states over the Schottky barrier, and not electron-hole pair generation in the depletion region, as was previously believed.

GGG単結晶の酸性溶液によるメカノケミカルポリシング特性

GGG single crystals used for a magnetic bubble device were polished mechanically and chemically, and the effects of polishing solutions were investigated experimentally. Results obtained are as follows:(1) The stock removal in mechano-chemical polishing using 1 N H2SO4 solution and 1 μm-Al2O3 powders at 20°C is higher than when using 1 N HCl solution. On the other hand, the etching rate by 1 N H2SO4 solution is lower than that by 1 N HCl solution at 20°C, and is reversed in temperatures about 80°C. The temperature at the work surface in mechanochemical polishing is found to be 70-160°C, according to the Arrhenius equation.(2) The stock removal using 3 N H2SO4 solution and 0.2 μm-Cr2O3 powders is about 1.5 times as large as the stock removal when using the same solution and 1 μm-Al2O3 powders, although Cr203 powders are smaller and softer than Al203 powders. The mechano-chemical polishing force using 0.2 μm-Cr2O3 powders and polishing solution is larger than the case of 1 μm-Al2O3 powders. It is related to the stock removal by chemical action in mechanochemical polishing.

軟質粒子によるSi単結晶のメカノケミカルポリシング

This paper describes experimental results for polishing Si single crystals by means of “mechanochemical polishing method with soft powders”. In this method the powders used are softer than the work materials and react chemically with them. It is shownthat high precision polishing of Si single crystals is materialized by utilizing the solid state reaction between the powder and the oxide layer formed on the Si surface. The followingare the main results obtained.(1) A mirror surface free from mechanical damages is easily produced by polishing with soft powders such as BaCO3 and Fe3O4. High polishing rates are obtainable especially in dry processing.(2) Polishing by a relatively rigid polisher e. g. bakelite brings a polished surface of high flatness.(3) The oxidized and worked layer remaining on the surface polished by BaCO3 powder is much thinner than by conventional mechanical polishing.