Abstract: A method for the manufacture of silicon layers containing boron and phosphorus dopants wherein the silicon wafers are positioned in a reaction chamber into which there is introduced, from separate sources, (a) tetraethylorthosilicate as a source of silicon dioxide, (b) trimethylborate as a source of boron, and (c) a phosphorus source. The three reactants are decomposed in the reaction chamber to deposit silicon dioxide doped with boron and phosphorus onto the wafers, the decomposition being carried out at a temperature of at least 600.degree. C. and at a substantially subatmospheric pressure.

Abstract: A method of producing a defined arsenic doping in silicon semiconductor substrates is provided. Preferably, the arsenic doping is produced in the sidewalls and floors of trenches having high aspect ratio which are etched into the substrates. An arseno-silicate glass layer is deposited into these trenches to be used as a diffusion source, the glass layer being removed after the diffusion. The arseno-silicate glass layer is deposited by thermal decomposition from the vapor phase of tetraethylortho silicate Si)OC.sub.2 H.sub.5).sub.4 and triethylarsenate AsO(OC.sub.2 H.sub.5).sub.3. A steep and reproducible doping profile having constant, maximum penetration depth and high arsenic concentration in the substrate surface which is needed for VLSI semiconductor circuits is obtained through the process of the present invention.