Abstract: A device and a method for reducing particle exposure to substrates during thermal treatment are disclosed. Semiconductor wafers may be rotated on a device within a process chamber divided into two partial chambers such that a first partial chamber contains the substrate to be thermally treated and a second partial chamber contains at least parts of the rotation device. Between the partial chambers, a flow of gas is set such that gas from the second partial chamber is substantially prevented from passing into the first partial chamber. In this way, particles which are produced by rotation abrasion in the second partial chamber are largely prevented from passing onto the substrate to be thermally treated. This device and this method are particularly advantageous if the rotation is realized by means of a gas drive, wherein the gas used for the rotation can be introduced directly into the second partial chamber.