In order to increase the sheet resistance of Sb2Te3 (ST) thin films, nitrogen-doped Sb2Te3 (N-doped ST) thin films were deposited using DC magnetron sputtering. The nitrogen gas flow rate was changed from 0 sccm (ST(0)) to 6 sccm (ST(6)) during the deposition. The sheet resistances of N-doped ST films rapidly increased as the nitrogen gas flow rate increased. Phase-change random access memory (PRAM) test cells were fabricated using N-doped ST thin films. The threshold voltages of ST(0) and ST(6) PRAM test cells were 1.09 and 0.70 V, respectively. The mismatch problem of 1st and 2nd sweeping was hypothesized to be caused by poor adhesion and Te segregation between the ST film and TiN.
Keywords: Sb2Te3(ST), PRAM, Threshold voltage, Nitrogen, Adhesion.