IEDM 2019
Conference paper

Ultra-scaled Conformal Scavenging Electrode with Superior Tunability for Short-channel RMG FinFET Workfunction and all-ALD 3D-compatible ReRAM

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A baseline TiAl-containing ALD electrode is established, with properties in line with reported workfunction (WF) materials for scaled RMG nFETs, values below 4.6eV requiring a 25Å layer. Furthermore, a novel ALD metal-compound material, MX, is shown to enable at least 10Å further scaling of the electrode stack due to its superior scavenging power. It can be finely tuned by the film thickness, allowing for a remarkable 20-30meV WF delta per ALD cycle over a minimum 600meV range. The wet etchability of the electrodes makes multi-Vt and dual-WF integration possible. MX does not degrade transfer characteristics and reliability of RMG FinFETs, while the thinner nWF electrode enables reduced gate resistance, as verified down to 20nm metal gate lengths. For the first time, taking advantage of the MX compound scavenging power to control oxygen filaments, we demonstrate an all-ALD HfO2-based ReRAM. Forming voltages match those achieved by optimized PVD contacts, while scaling the active electrode thickness by a factor of 4x, down to 5nm. Conformality of the layers enables vertical-ReRAM architectures with reduced line resistance. We conclude the developed electrode can facilitate both logic scaling beyond the 10nm node, and 3D memory technology.