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1,1,2,2,9,9,10,10-Octamethyl-1,2,9,10-tetrasila[2.2]paracyclophane, the first [2.2]paracyclophane bridged by heteroatoms, has been prepared. UV, IR, and 1H- 13C- and 29Si-NMR spectral together with X-ray crystallographic data are recorded. The compound displays a strong σπ mixing between Si–Si bonds and aromatic rings as evidenced by a large red shift in UV spectra.

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A new positive‐working photosensitive system of silicon polymer, containing silylether groups in the main chain and a photo‐induced acid precursor was investigated. The silicon polymer is hydrolized by a photogenerated acid and degraded to low molecular weight compounds. Thus the effect of solubility inhibition of the polymer is diminished. The higher photosensitivity of this system as compared with 1,2‐quinone diazide compounds is due to the catalytic reaction of the acid on the hydrolysis of the silicon polymer. The chemical structure around silylether groups in the polymer, in particular more hydrophilic and less steric structures, affects the rate of hydrolysis and thus the photosensitivity. Among various types of photo‐induced acid precursors examined, e.g., s‐triazine and 1,3,4‐oxadiazole compounds substituted by trihalomethyl groups were effective.

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