Device and method for depositing one or more layers on a substrate

A process for depositing one or more layers on at least one substrate which is disposed on a temperature controlled susceptor in a reaction chamber, using at least one liquid or solid starting material for at least one of the reaction gases used, and if appropriate at least one further reaction gas which is in gas form at room temperature, in which process the liquid or solid starting material(s) are converted from the liquid or solid phase directly into the vapor phase in one or more evaporators before they enter the reaction chamber, the reaction gas(es) being admitted to a gas inlet unit, which has a plurality of separate gas paths, the number of which is less than or equal to the number of reaction gases used, which gas paths have a multiplicity of outlet openings, which are disposed in such a way that the various reaction gases enter the reaction chamber distributed uniformly over the substrate area, and that the temperature of the reaction gas(es) on their respective gas path is controlled by the gas inlet unit, heat being supplied to or dissipated from the gas inlet unit by the susceptor on the side of the gas inlet unit directed towards the susceptor, and, on the other side, heat is dissipated to a heat sink or supplied from a heat source through a gas purged gap, the heat resistance of which is adjustable by changing the gas composition, wherein

• the reaction gases enter the reaction chamber spatially separate in such a manner that they substantially do not react with one another before reaching the surface of the substrate(s),
• for a sealing or throttling separation of the gap with respect to the reaction chamber, the heat resistance of the gap is also adjustable by changing the gas pressure, and
• by means of at least one buffer volume between the two sides of the gas inlet unit, the buffer volume being associated with the gas inlet unit, and in particular formed by the gas paths, a variable heat resistance is set by changing the pressure and/or the composition of the gases in the buffer volume.

A method for uniformly depositing layers on a substrate comprising the steps of:

• positioning a substrate on a temperature controlled susceptor in a reaction chamber;
• converting a liquid or a solid to reaction gases formed at room temperature;
• admitting the reaction gases to an inlet unit having a plurality of separate gas paths that are at least equal to the number of reaction gases used;
• passing the reaction gases through a buffer volume;
• controlling a temperature of the reaction gases in the buffer volume;
• directing each reaction gas through a different gas path;
• injecting each reaction gas into a reaction chamber, each reaction gas being injected through a plurality of outlet openings spatially separate from each other such that each reaction gas does not react with one another prior to reaching a surface area of the substrate.