NiFeCo/ Cu /Co trilayers were formed on 4$^{circ}$ tilt-cut Si(111) substrates with a Cu(50$AA$) underlayer and large-scaled test magnetoresistive RAM (MRAM) cells were fabricated using a conventional lithographic process. NiFeCo / Cu /Co trilayers deposited on the same templates without any applied magnetic field showed strong in plane uniaxial magnetic anisotropy and excellent magnetoresistive (MR) properties such as high MR ration and sensitivity within a low external magnetic field, which are suitable properties for a MRAM application. In order to obtain optimized MR results in NiFeCo /Cu /Co trilayers, the thickness of Cu spacer was varied. Interlayer coupling between two magnetic layers was observed and it was found that the MR properties were strongly dependent on the coupling force, especially near 20 $AA$ of Cu spacer thickness. Test MRAM cells were fabricated using the optimized NiFeCo (60$AA$)/ Cu (25$AA$)/ Co (30$AA$) trilayer thin films. With a 10 mA of sense current and 5$ imes$$10^5$ of word current, 10 mV of signal output was obtained, which implies the strong potentials of NiFeCo/ Cu /Co trilayer thin films for a MRAM application.