N doping is proposed to enlarge sensing margin of W0.08(Sb2Te)0.92 based high-temperature phase-change memories (PCMs). The sensing margin is increased from 30 to 5 × 103, with an increase from 145 °C to 158 °C in data retention. The grain size is reduced to 10 nm. The PCM based on N-W0.08(Sb2Te)0.92 shows the fast operation speed of 30 ns and good cycling ability of >103. By X-ray photoelectron spectroscopy and ab initio calculation, the W atoms are suggested to locate in the Sb positions and interstices of the lattice. The W atoms in interstice will bond to N atoms during N doping.