Pseudo-spin-valve device performance for giant magnetoresistive random access memory applications

Abstract

Write and read performance were characterized in current-in-plane pseudo-spin-valve (PSV) devices. The PSV stack evaluated in this work was Ta 5 nm/NiFe 6.5 nm/CoFe 1.5 nm/Cu 3.7 nm/CoFe 1.5 nm/NiFe 4.5 nm/Ta 20 nm. Minimum resistance (R/sub min/), storage layer switching fields in forward and reverse sweep directions (H/sub f/ and H/sub r/) for write, and resistance change (/spl Delta/R) for readback are reported as a function of temperature (25 to 100/spl deg/C) and bit width (500 to 900 nm). R/sub min/ and /spl Delta/R temperature coefficients are reported as a function of sense current (0.1 to 1 mA), I/sub s/. H/sub f/ and H/sub r/ temperature coefficients are reported as a function of I/sub s/ and applied hard-axis field (0 to 30 Oe), H/sub d/. The variation of R/sub min/ with temperature, normalized to R/sub min/ at 25/spl deg/C to account for bit width (BW), was approximately +1.4 m/spl Omega///spl deg/C//spl Omega/. The variation of /spl Delta/R with temperature, normalized to R/sub min/ at 25/spl deg/C, was approximately -60 /spl mu//spl Omega///spl deg/C//spl Omega/. The temperature dependences of R/sub min/ and /spl Delta/R were attributed to increased scattering as thermal energy increased. H/sub f/ and H/sub r/ show weak temperature dependence, between approximately 0 and -25 mOe//spl deg/C and 0 and +25 mOe//spl deg/C, respectively. The weak temperature dependence of H/sub f/ and H/sub r/ was ascribed to the weak temperature dependence of magnetization, anisotropy, and exchange over the measured range of temperatures.