Abstract: Silicon wafers are first subjected to an oxidative treatment and subsequey to exposure to organosilicon compounds which contain at least one radical in the molecule which is hydrolyzably bound to the silicon and at least one radical in the molecule having hydrophilic properties. Depending on the compound selected, more or less strongly hydrophilic or hydrophobic properties of the silicon surface can consequently be established under mild conditions. The wafers treated in such a manner have a high storage stability and retain their surface nature even under difficult climatic circumstances. The surface nature present after the oxidative treatment can then be restored particularly easily by hydrolysis.

Abstract: This invention relates to an improved process for preparing acyloxysilanes and acyloxysiloxanes which comprises conducting an aliphatic carboxylic acid in vapor form upwards from the bottom of a column countercurrent to the flow of a chlorosilane in which the carboxylic acid is introduced into the column at such a rate that the carboxylic acid does not exceed about 1.3 mol per gram atom of Si-bonded chlorine in the column while removing the acyloxysilane from the bottom of the column.The acyloxysiloxanes are prepared by conducting an aliphatic carboxylic acid upwards from the bottom of a column in vapor form countercurrent to the flow of a chlorosilane while introducing up to about 10 percent by weight of water based on the weight of the carboxylic acid into the column and removing the acyloxysiloxane from the bottom of the column.