Tailoring sidewall profiles of magnetic tunnel junctions fabricated with various etching conditions

Abstract

Structural and compositional characteristics of MgO-based magnetic tunnel junctions were characterized using advanced transmission electron and focused-ion beam microscopies. These junctions were fabricated from two ferromagnetic layers separated by a dielectric one and have a switchable resistance that depends upon the relative magnetizations of those two ferromagnetic layers. Certain etching conditions were used to complete the fabrication process aiming to achieve sharp-edge profiles on either side of the pillars. Controlling the edge profiles of those fabricated pillars enables to avoid shortcuts that induce magnetoresistance effect. Not only structural properties of each layer in the MgO junction are characterized, but its compositional characteristics are also explored with electron energy loss spectroscopy, this aims to elucidate the role of elements existing in the given MgO structure. Results of this work are of technological interest since they provide a better understanding in the microstructural properties of the MgO-based magnetic tunnel junctions.

Growth mechanisms of hBN crystalline nanostructures with rf sputtering deposition: challenges, opportunities, and future perspectives

“…d = 3 cm or 6 cm and α = 0°or 90°, if the deposition time is known. We also used two X-TEM methods [112], however we highly analyze the results for the case with X-TEM specimens using focused ion beam (FIB) technique. One type of direct TEM sample used an amorphous Si 3 N 4 membrane to grow an hBN film on top, and then directly measure the projection of hBN nanowalls (hBN-NWs) or hBN particles on it.…”

“…Moreover, if the film thickness of samples is less than 500 nm, X-TEM samples were prepared to measure their thickness accurately by a TEM. Here, we used both the gentle ion milling (GentleMill TM ) and FIB techniques [112,[121][122][123][124][125][126][127] for sample cross-sectioning. These two methods were well described in our previous work [112].…”

“…Here, we used both the gentle ion milling (GentleMill TM ) and FIB techniques [112,[121][122][123][124][125][126][127] for sample cross-sectioning. These two methods were well described in our previous work [112]. Therefore, we skip describing it in this work.…”

“…The FIB X-TEM samples are all about 100nm thick which is suitable for the characterization of structural and chemical properties, realized by Dr. Svetlana Kyerschuk at EMAT, Belgium. The detailed steps of FIB specimen preparation were described in [112].…”

“…The 300 nm-thick hBN film is aimed at seeing the entire film thickness of the X-TEM specimen using TEM technique. Since this specimen has only a single layer of hBN that grows onto the Si substrate, hence we prepared the X-TEM specimen by the GentleMill TM method [112] to reduce a certain damage from the highenergy ion beam like FIB. From the X-TEM image, we can see very clearly that the two hBN films are facing each other because of using GentleMill TM preparation method, leading the two Si substrates appearing on opposite The SEM images of these samples are also seen on the right panels where the density of hBN-NWs is low in (b), while it is higher in (c) at which the wall branches of hBN-NWs emerged and participated in the growth process.…”