The fluorine-doped n-type superconductors Ndl.s5Ce0.15CuO4_x_yFy (nominal composition) are synthesized with CuF z as one of the reactants. Especially, it is found that the superconductivity of Nd1.85Ce0.15CuO4_~ is improved with Tc °n= 27 K, T ° = 15.5 K when CuF 2 is taken as a source of atmosphere; the temperature dependence of the resistance exhibits a metallic conducting behavior above T c. Magnetization measurements showed 30% of superconducting phase fractions by means of SQUID magnetometry, which was a better result of superconductivity in (Nd,Ce)-Cu-O bulk samples than when prepared under ambient pressure. Compared with the case of F undoping, F doping not only induces a transition from semiconductivity to metallic conductivity and decreases the normal-state resistivity, but also increases the Tc °n and T °, and decreases the transition width AT c. In particular, the superconductivity of the samples is sensitive to the form of the dopant source and sintering procedures. Especially, the Nd 1.85Ce0.15CuO3.6F0.4 sintered only in air also exhibits superconductivity with T °n = 19.5 K, but does not reach zero resistance, which has not been reported before. X-ray diffraction experiments indicate that fluorine atoms do enter the superconducting phase lattice.