A data communication system includes a host device, a readerwriter device and a plurality of contactless identification tags. The MSO may be L-methionine S-sulfoximine, L-methionine R-sulfoximine, or diastereomeric mixture of LSMSO and LRMSO. Therefore, the present invention can prevent oxidization of a diffusion prevention film due to oxygen existing in a Ru film during annealing process performed after deposition of a Ta2O5 film and thus improve reliability of the device. In the method of the invention, the sintering step is performed while the gel plate is mounted on a support surface, separated by a thin layer of refractory powder.