A conveyor assembly suitable for use in a substrate processing system includes: at least one substrate carrier having a substrate-carrying surface configured to support at least one substrate; a processing track; a return track; a drive system configured to drive the substrate carrier along the processing track and the return track; and at least one swivel unit configured to pivot the substrate carrier around a substantially horizontal axis from a first orientation into a second orientation, and/or vice versa. Also provided is a method for conveying a substrate carrier including: providing a substrate carrier; positioning the substrate carrier in a first orientation; conveying the substrate carrier along a first track; and rotating the substrate carrier around a substantially horizontal axis into a second orientation.