Material selection for hybrid floating gate NAND memory applications. Issue 2 (28th January 2016)

• Record Type: Journal Article
• Authors: Lisoni, Judit G.; Breuil, Laurent; Blomme, Pieter; Meersschaut, Johan; Bergmaier, Andreas; Dollinger, Günther; Van den bosch, Geert; Van Houdt, Jan
• Is Part Of: Physica status solidi. Volume 213:Issue 2(2016:Feb.)
• Page Start: 237
• Page End: 244
• Publication Date: 2016-01-28
• Subjects: flash NAND -- high‐k integrate dielectrics -- high work function metal gates -- hybrid floating gate; Solid state physics -- Periodicals; Solids -- Industrial applications -- Periodicals; 530.41
• DOI: 10.1002/pssa.201532829
• Languages: English
• ISSNs: 1862-6300

Abstract

Abstract : This article discusses the materials aspects involved in the successful integration of hybrid floating gate (HFG) devices for NAND applications. In HFG, a Si(n type)\metal(p type) stack replaces the standard poly‐Si FG. The high work function metal helps to enlarge the program window by limiting the leakage through the high‐ k intergate dielectric (IGD); the use of high‐ k IGD enables to scale the equivalent oxide thickness (EOT) of the HFG cell. Our recent progresses in the understanding of the materials characteristics (IGD crystallinity and HFG‐IGD thermal stability) that influence memory performance have allowed to demonstrate that HFG can be a solution to scale planar flash beyond the 20 nm node with the best preferable hybrid floating gate structure being a Ru‐based HFG and a 3‐layers IGD stack of HfAlO\Al2 O3 \HfAlO. Indeed, through the correct selection and combination of materials for process conditions that are relevant in flash memory fabrication flows, we will show that program windows can be suitably engineered. Finally, the materials challenges for keeping acceptable memory retention characteristics are also highlighted. Abstract : The authors review the material challenges involved in the successful integration of hybrid floating gate (HFG) devices, an alternative to scale planar NAND flash beyond the 20 nm node. In HFG, the standard poly‐Si FG is replaced by a Si(n type)\metal(p type) stack. Understanding the material aspects that influence memory performance allows to propose as the best preferable HFG structure a Ru‐based HFG and an intergate‐dielectric (IGD) stack of HfAlO\Al2 O3 \HfAlO.