Devices and methods for selectively oxidizing silicon are described herein. An apparatus for selective oxidation of exposed silicon surfaces includes a thermal processing chamber with a plurality of walls, first inlet connection and a second inlet connection, wherein the walls define a processing region within the processing chamber, a substrate support within the processing chamber, a hydrogen source connected with the first inlet connection, a heat source connected with the hydrogen source, and a remote plasma source connected with the second inlet connection and an oxygen source. A method for selective oxidation of non-metal surfaces, can include positioning a substrate in a processing chamber at a temperature less than 800° C., flowing hydrogen into the processing chamber, generating a remote plasma comprising oxygen, mixing the remote plasma with the hydrogen gas in the processing chamber to create an activated processing gas, and exposing the substrate to the activated gas.