Method for epitactic precipitation of crystalline material from a gaseous phase, particularly for semiconductors

Claim 1

Continuous method of etching and epitactic precipitation of monocrystalline layers of a semiconductor of the group consisting of silicon and germanium upon monocrystalline substrate wafers of the same semiconductor, which comprises placing monocrystalline substrates upon movable carriers of inert material, continuously passing said carriers through a tubular reaction vessel having an inlet point at one end and an outlet point at the other end, heating said carriers with said substrate wafers in the reaction vessel first through a zone II of a first, higher temperature and immediately thereafter through an adjacent zone I of a second, lower temperature, while introducing into the reaction vessel countercurrent to the movement of the substrate wafers a gas consisting of the halide of the semiconductor to be precipitated and hydrogen, the second temperature being at a value which effects epitactic precipitation from the gas of monocrystalline layers of the semiconductor on the substrate wafer in the zone I and the first temperature being at a value which effects etching of the surfaces of the substrate wafers in the zone II by the gas exhausting from the zone I through the zone II.