A semiconductor process includes the following steps. A dielectric layer is formed on a substrate. A barrier layer is formed on the dielectric layer. An ammonia thermal treatment process with a processing temperature of 650° C.˜700° C. and a nitrogen containing gas annealing process with a processing temperature of 900° C.˜1000° C. are sequentially performed on the barrier layer. The present invention also provides a semiconductor process including the following steps. A dielectric layer is formed on a substrate. A first nitrogen containing thermal treatment process is performed on the dielectric layer. A barrier layer is formed on the dielectric layer. A second nitrogen containing thermal treatment process and then an annealing process are performed in-situ on the barrier layer.