Aixtron Ag

Michael Bremser

Gerhard Karl Strauch

Martin Dauelsberg

The invention relates to a method for depositing especially, crystalline layers onto especially, crystalline substrates, in a process chamber of a CVD reactor. At least one first and one second reaction gas are each led into a gas outlet area in an input area of the process chamber, by means of separate delivery lines. The gas outlet areas lie one above the other between the floor of the process chamber and the cover of the process chamber and have different heights. The first reaction gas flows out of the gas outlet area that is situated next to the process chamber floor, optionally together with a carrier gas. A carrier gas is added at least to the second reaction gas, which flows out of the gas outlet area lying further away from the process chamber floor. The flow parameters are selected in such a way that the second reaction gas is essentially only pyrolytically decomposed in the inlet area and the products of decomposition diffuse crosswise to the direction of Dow of the gases to a substrate located on the process chamber floor, in a deposition area which is located downstream of the input area. Upon reaching said substrate, said products of decomposition condense to form a layer, together with products of decomposition of the first reaction layer. The invention aims to ensure that the decomposition of the organometallic products of decomposition takes place essentially only in the inlet area, even in the case of longer deposition areas, and to ensure that the partial pressures of the products of decomposition (depletion) in the gas phase above the deposition area maintain an essentially linear course. To this end, the invention provides that the kinematic viscosity of the carrier gas that is added to the second reaction gas is adjusted, especially by mixing two gases which differconsiderably in terms of their kinematic viscosity, in such a way that the quotient of Reynolds numbers in the two gas outlet areas is approximately one for essentially approximately identical average gas speeds.

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Pasadena, CA, United States of America

Michael Bremser