A device for coating one or more yarns by a vapor deposition method, the device including a treatment chamber defining a first and a second treatment zone in which at least one yarn is to be coated by performing a vapor deposition method, the first and second zones being separated by a wall and the first zone surrounding the second zone, or being superposed on the second zone; a conveyor system to transport the at least one yarn through the first and second zones; a first injector device to inject a first treatment gas phase into the first zone and a first removal device configured to remove the residual first gas phase from the first zone; and a second injector device configured to inject a second treatment gas phase into the second zone, and a second removal device configured to remove the residual second gas phase from the second zone.