相補形誘電体分離基板の製作におけるSi異方性エッチング

概要

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Anisotropic etching of silicon has been used to form well-shaped islands and smooth etched surfaces on single crystal silicon. To accomplish this, two problems must be overcome ; one is a corner undercut which causes deviation from normal shapes. The other is the appearance of small pyramidal hillocks called micropyramids (MP) on the etched surface, which cause incomplete isolation between the islands, and result in a degradation of the bipolar transistor characteristics. The results obtained from corner undercut and MP formation experiments are as follows : (1) Alcohols used as surfactants in KOH solutions inhibited corner undercut but caused MP formation. There, was a strong correlation between the inhibition effects and the density of MP appearance, depending on the alcohol molecular weight. (2) The optimal loca-tion for the compensative patterns was to place the center of these patterns at the corner point of the etch masks. Optimum size depended on etch depth and the kind of alcohol. (3) It was very difficult to completely inhibit MP formation, but a mirror surface with very few MP (less than 10/cm^2) was formed with both KOH+ethyl alcohol solution and defect-free substrates. These results were applied to the fabrication of complementary dielectric isolated substrates, and it was confirmed that high-voltage LSIs formed on these substrates operated normally.
公益社団法人精密工学会の論文
1985-09-05