No abstract

No abstract

The common memory technologies used in the traditional memory hierarchy, are increasingly constrained by fundamental technology limits. The increasing leakage power for SRAM and refresh dynamic power for DRAM has posed challenges to circuit and architecture designers. Emerging memory technologies such as spin transfer torque RAM (STT-RAM), phase-change RAM (PCRAM), and resistive RAM (RRAM) are being explored as potential alternatives to existing memories in future computing systems. Especially, due to the excellent compatibility with CMOS process and ease of 3D integration, RRAM provides a promising potential for embedded and standalone application. In this talk, current status of RRAM technology will be discussed, including switching mechanism, array architecture, 3D integration, target applications, challenges and future trends. A new era of convolutional computer architectures could be expected after the mature of emerging new NVM technologies.

The influence of the deposition temperature during the reactive sputtering process on the microstructure of thin Ir and IrO2 films deposited on oxidized Si substrates was investigated and related to the oxygen barrier effectiveness. For this purpose differential thermal analysis combined with residual gas analysis by mass spectrometry was used for the investigation of the microstructural and chemical behavior of the as-sputtered IrO2 films upon heating. Moreover, in situ stress relaxation analyses up to 900 °C, in and ex situ x-ray diffraction measurements were done for various annealing conditions. The investigated polycrystalline IrO2 films exhibited a large compressive stress and a distorted lattice due to the sputter deposition process. It is demonstrated that a high deposition temperature involves a delayed relaxation of the IrO2 grains which is causing an extrinsic, enhanced defect controlled oxygen mobility for the annealing temperatures below the recrystallization. The well-known low intrinsic oxygen diffusivity was only found in those samples which show—in addition to the recovery process—a recrystallization at low temperatures and thus a formation and growth of a new generation of grains with a lattice spacing as in bulk IrO2. Moreover, the oxygen diffusion in Ir films was investigated and the oxygen was found to penetrate the Ir films very quickly at elevated temperatures. The microstructure of the films was investigated by cross sectional transmission electron microscopy and it is shown that the cold-sputtered columnar IrO2 films protect the underlying layers from oxidation during a 700 °C high temperature oxygen anneal with an optimized Ir/IrO2 oxygen barrier stack.

Abstract. The growth of Pt(lll) by Pt vapour deposition is studied by He diffraction as a function of substrate temperature and deposition rate. At a deposition rate of about 2.5 x 10 -2. monolayers/second several growth modes are observed: layer-by-layer (2D-) growth at 450 K <~ Ts <~ 800 K, multilayer (3D-) growth at 340 K <~ Ts <~ 450 K and reentrant layer-by-layer (2D-) growth at Ts <~ 340 K. The observed growth modes and in particular the reentrant 2D-growth are shown to be characteristic of growing Pt(111) under clean conditions, i.e. not influenced by contaminants. The influence of the intra-and interlayer mass transport on the growth mode is discussed in the light of experimental and simulation results. The 3D-growth mode is attributed to the existence of an activation barrier which suppresses the descent of adatoms from the top of the growing adatom islands onto the lower terraces. The barrier can be overcome by thermal adatoms at Ts >~ 450K enabling interlayer mass transport which leads to 2D-growth. The reentrant 2D-growth occurs due to a break down of this barrier for small, irregularly shaped islands.