Fully ALD-grown TiN/Hf0.5Zr0.5O2/TiN stacks: Ferroelectric and structural properties

Since the discovery of ferroelectricity (FE) in HfO2-basedthin films, they are gaining increasing attention as a viable alternative to conventional FE in the next generation of non-volatile memory devices. In order to further increase the density of elements in the integrated circuits, it is essential to adopt a three-dimensional design. Sinceatomic layer deposition(ALD) processes are extremely conformal,ALD is the favored approach in the production of 3Dferroelectric random access memory. Here, we report the fabrication of fully ALD-growncapacitors comprising a 10-nm-thick FE Hf0.5Zr0.5O2 layer sandwiched between TiNelectrodes, which are subjected to a detailed investigation of the structural and functional properties. The robust FE properties of Hf0.5Zr0.5O2films incapacitors are established by several alternative techniques. We demonstrate a good scalability of TiN/Hf0.5Zr0.5O2/TiN FEcapacitors down to 100-nm size and thepolarization retention in the test “one transistor-one capacitor” (1T-1C) cells after 1010 writing cycles. The presence of a non-centrosymmetric orthorhombic phase responsible for FE properties in the alloyed polycrystalline Hf0.5Zr0.5O2films is established by transmission electron microscopy. Given the ability of theALD technique togrow highly conformalfilms and multilayered structures, the obtained results indicate the route for the design of FE non-volatile memory devices in 3D integrated circuits.

Source: Applied Physics Letters - November 8, 2016 Category: Physics Authors: Sergei Zarubin, Elena Suvorova, Maksim Spiridonov, Dmitrii Negrov, Anna Chernikova, Andrey Markeev and Andrei Zenkevich Source Type: research