Effect of MgO spacer and annealing on interface and magnetic properties of ion beam sputtered NiFe/Mg/MgO/CoFe layer structures

Abstract

Ferroelectric vs. structural properties of large-distance sputtered epitaxial LSMO/PZT heterostructures AIP Advances 2, 032184 (2012) Magnetron-sputter deposition of high-indium-content n-AlInN thin film on p-Si(001) substrate for photovoltaic applications J. Appl. Phys. 112, 063114 (2012) Reactive sputter deposition of pyrite structure transition metal disulfide thin films: Microstructure, transport, and magnetism J. Appl. Phys. 112, 054328 (2012) Strong free-carrier electro-optic response of sputtered ZnO films J. Appl. Phys. 112, 053514 (2012) Influence of capping layers on CoFeB anisotropy and dampingThe effect of variation in the thickness of ion assisted ion beam sputtered MgO spacer layer deposited at oxygen ion assisted energy of 50 eV on the extent of magnetic coupling of NiFe and CoFe layers in Si/NiFe(10 nm)/Mg(1 nm)/MgO(2,4,6 nm)/CoFe(10 nm) sandwich structure is investigated. At MgO spacer layer thickness of 4 nm, the separate reversal of magnetizations of the two ferromagnetic layers is observed in the hystresis loop recorded along easy direction. This results in a 3.5 Oe wide plateau like region during magnetization reversal, which became 4.5 Oe at 6 nm thin MgO. At 2 nm thin MgO, the absence of plateau during magnetization reversal region revealed ferromagnetic coupling between the two ferromagnetic layers, which is understood to arise due to the growth of very thin and low density (1.22 gm/cc) MgO spacer layer, indicating the presence of pinholes as revealed by x-ray reflectometry. After vaccum annealing (200 C/1 h), the plateau region for 4 and 6 nm thin MgO case decreased to 1.5 Oe and 2.0 Oe, respectively, due to enhanced interface roughness/mixing. In addition, an enhancement of the in-plane magnetic anisotropy is also observed.

Effect of annealing on the temperature dependence of inelastic tunneling contributions vis-à-vis tunneling magnetoresistance and barrier parameters in CoFe/MgO/NiFe magnetic tunnel junctions

“…X-ray photoelectron spectroscopy investigations on as deposited MgO barrier confirmed the presence of interstitial oxygen ion in the MgO 16 To investigate the changes taking place at the two CoFe-MgO and MgO-NiFe interfaces as a result of the two annealing treatments, we recorded the XRR data on planar MTJs of size 10 mm  10 mm and performed the simulation. 40 The G 0 1.64947  10 À4 X À1 1.59433  10 À4 X À1 1.45912  10 À4 X À1 r 2 7.20789  10 À8 X À1 K À5/3 1.21042  10 À10 X À1 K À5/3 8.35513  10 À8 X À1 K À5/3 r 3 3.63638  10 À27 X À1 K À10/4 7.63345  10 À23 X À1 K À10/4 1.27933  10 À27 X À1 K À10/4 r 4 2.0918  10 À26 X À1 K À18/5 2.06949  10 À15 X À1 K À18/5 1.49708  10 À30 X À1 K À18/5 r 5 3.92225  10 À26 X À1 K À28/6 4.41945  10 À16 X À1 K À28/6 1.13101  10 À24 X À1 K À28/6 r 6 3.68635  10 À33 X À1 K À40/7 5.13316  10 À18 X À1 K À40/7 5.25614  10 À19 X À1 K À40/7 r 7 1.12912  10 À23 X À1 K À54/8 2.28857  10 À20 X À1 K À54/8 7.33386  10 À20 X À1 K À54/8 r 8 2.9235  10 À25 X À1 K À70/9 5.06332  10 À23 X À1 K À70/9 4.4402  10 À22 X À1 K À70/9 r 9 1.55947  10 À25 X À1 K À88/10 1.80991  10 À25 X À1 K À88/10 4.20538  10 À28 X À1 K À88/10 r 10 6.21207  10 À28 X À1 K À108/11 7.8460  10 À28 X À1 K À108/11 r 11 1.77214  10 À30 X À1 K À130/12 1.0000  10 À48 X À1 K À130/12 r 12 3.0000  10 À48 X À1 K À154/13 r 13 1.98389  10 À50 X À1 K À180/14 r 14 3.1181  10 À37 X À1 K À208/15 r 15 8.4018  10 À40 X À1 K À238/16 r 16 1.16704  10 À42 X À1 K À270/17 r 17 1.66188  10 À44 X À1 K À304/18 r 18 2.43507  10 À47 X À1 K À340/19…”

Testing STT-MRAM: Manufacturing Defects, Fault Models, and Test Solutions

“…As illustrated in Figure 3.19, oxygen atoms can diffuse out of MgO, leaving behind oxygen vacancies, thus severely degrading TMR value [78]. Worse still, diffusion of Ta from the seed layer to MgO layer has been reported in several papers [121,122], which scavenges O from MgO. After MTJ multi-layer deposition, annealing and optical lithography processing, the next crucial step is to pattern individual MTJ nanopillars [123].…”

Survey on STT-MRAM Testing: Failure Mechanisms, Fault Models, and Tests

“…7, oxygen atoms can diffuse out of MgO, leaving behind oxygen vacancies, thus severely degrading TMR value [43]. Worse still, diffusion of Ta from the seed layer to MgO layer has been reported in several papers [78,79], which scavenges O from MgO.…”