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991.
The plasmochemical etching of SiO2 in CF4 + O2 plasma is considered. During the experiment SiO2 films are etched in CF4 + O2 plasma at temperatures of 300 and 350 K. The dependences of plasmochemical etching rates of SiO2 on O2 content in the feed are measured. The experimental measurements are compared with theoretical calculations. The obtained theoretical results are used to predict the real dimensions of etched trenches. It is found that decrease in temperature reduces lateral undercutting due to decreased desorption of formed SiF4 molecules from the sidewalls. 相似文献
992.
F. Scott Johnson Donald S. Miles Douglas T. Grider J. J. Wortman 《Journal of Electronic Materials》1992,21(8):805-810
Polycrystalline SiGe etches that are selective to silicon dioxide as well as silicon are needed for flexibility in device
fabrication. A solution of NH4OH, H2O2, and H2O has been found to selectivity etch polycrystalline silicon-germanium alloys over both silicon and silicon dioxide. Optimum
composition of the solution was determined by maximizing etch rates for SiGe films with several germanium compositions. The
dependence of etch rates on germanium content, etching temperature, and doping concentration are reported. The etch rate and
selectivity are approximately exponentially proportional to the germanium content. Etching was found to be insensitive to
deposition method, doping method, and annealing conditions of the SiGe films. In addition, etching leaves a smooth silicon
substrate surface after removal of SiGe films. 相似文献
993.
在薄膜混合集成电路中,以铝导带代替金导带不失为一种廉价而很有前景的工艺,但铝与银浆的黏接在一定的温度和时间下,会产生一种绝缘金属间化合物,需要一定的电压才能击穿,从而使最终产品失效。采用Al-Ni复合导带可以解决上述问题,并得到满意的结果。 相似文献
994.
David A. Erasmus 《Journal of chemical ecology》1986,12(8):1755-1764
Pairing of males and females from single-sex infections results in the multiplication and differentiation of undifferentiated cells of the vitelline lobule culminating in the production of mature vitelline cells involved in egg shell formation. These changes are accompanied by increases in the rate of uptake of tyrosine, thymidine, and an increased accumulation of calcium. 相似文献
995.
J. Spavold 《Journal of Computer Assisted Learning》1989,5(3):145-160
Abstract This study was undertaken, in part, to analyse the means by which primary children familiarized themselves with a large database. Their approaches to the problems of coding data for entry were studied and the types of error and frequency of occurrence were recorded. Query formulation was studied in parallel with data entry, particularly the difficulties presented by the correct expression of queries, choice of tests and use of coded fields. Attention was paid to the age and sex of the children for both aspects of the study. 相似文献
996.
997.
The paper presents a study of the formation of wear grooves on near-eutectic aluminium–silicon alloy flats, by sliding a steel ball. The formation of the grooves are tracked on etched and unetched flats as functions of normal load and sliding distance. The groove is initially formed by plastic flow, and then expanded by micro-abrasion as the ball continues to slide on the groove. Etching causes surface hardening of the alloy, but, more importantly creates a surface topology that reduces the peak contact pressure, which discourages further plastic flow in the subsurface. This effect is rationalised using an existing contact mechanical model of indentation of rough surfaces. 相似文献
998.
用二甘醇双烯丙基碳酸脂(ADC)和过氧化苯甲酸(BPO),经本体热固聚合,研制了一种新型CR-39固体核径迹探测器,它的体蚀刻速度V_B=1.37μm/h,相对灵敏度V_a·V~(-1)_B=1.77,本底径迹密度B=9.8×10~(-5)径迹·mm~(-2)。它具有高灵敏度、低本底以及均匀、稳定的性能。 相似文献
999.
Rubidium hydrogen tartrate single crystals were grown in silica hydrogel. Controlled reaction was employed between tartaric
acid and rubidium chloride solutions by slow diffusion process in the gel medium. Colourless transparent crystals were grown
at room temperature. The average density of crystals measured pyknometrically was 2·263 g cm−3. Thermal stability of the materials was studied. Chemical etching was employed to determine the perfection of these crystals. 相似文献
1000.
We solve the problem of two-dimensional flow of a viscous fluid over a rectangular approximation of an etched hole. In the absence of inertia, the problem is solved by a technique involving the matching of biorthogonal infinite eigenfunction expansions in different parts of the domain. Truncated versions of these series are used to compute a finite number of unknown coefficients. In this way, the stream function and its derivatives can be determined in any arbitrary point. The accuracy of the results and the influence of the singularities at the mask-edge corners is discussed. The singularities result in a reduced convergence of the eigenfunction expansions on the interfaces of the different regions. However, accurate results can be computed for the interior points without using a lot of computational time and memory. These results can be used as a benchmark for other methods which will have to be used for geometries involving curved boundaries. The effect of hole size on the flow pattern is also discussed. These flow patterns have a strong influence on the etch rate in the different regions. 相似文献