1. Understanding the Origin of Metal Gate Work Function Shift and Its Impact on Erase Performance in 3D NAND Flash Memories
- Author
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Sivaramakrishnan Ramesh, Arjun Ajaykumar, Lars-Åke Ragnarsson, Laurent Breuil, Gabriel Khalil El Hajjam, Ben Kaczer, Attilio Belmonte, Laura Nyns, Jean-Philippe Soulié, Geert Van den bosch, and Maarten Rosmeulen
- Subjects
work function ,effective work function ,dipole ,metal gate ,high-k ,SiO2 ,Mechanical engineering and machinery ,TJ1-1570 - Abstract
We studied the metal gate work function of different metal electrode and high-k dielectric combinations by monitoring the flat band voltage shift with dielectric thicknesses using capacitance–voltage measurements. We investigated the impact of different thermal treatments on the work function and linked any shift in the work function, leading to an effective work function, to the dipole formation at the metal/high-k and/or high-k/SiO2 interface. We corroborated the findings with the erase performance of metal/high-k/ONO/Si (MHONOS) capacitors that are identical to the gate stack in three-dimensional (3D) NAND flash. We demonstrate that though the work function extraction is convoluted by the dipole formation, the erase performance is not significantly affected by it.
- Published
- 2021
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