Performance and Reliability Features of Advanced Nonvolatile Memories Based on Discrete Traps (Silicon Nanocrystals, SONOS)

Abstract

In this paper, an overview of today's status and progress, as well as tomorrow's challenges and trends, in the field of advanced nonvolatile memories based on discrete traps is given. In particular, unique features of silicon nanocrystal and SONOS memories will be illustrated through original recent data. The main potentials and main issues of these technologies as candidates to push further the scaling limits of conventional floating-gate Flash devices will be evaluated.

Charge Spreading Effect of Stored Charge on Retention Characteristics in SONOS NAND Flash Memory Devices

“…Recently, however, the NAND Flash memory industry has faced the scaling limitation of the conventional floating gate (FG) NAND cell. For a promising solution as the alternative technology to replace FG flash memory, the charge trap type flash memory, like Silicon-Oxide-Nitride-Oxide-Silicon (SONOS) device has been focused since it provides simpler process steps than FG [3], lower cell-to-cell coupling [4], and virtual immunity to stress-induced leakage current (SILC) [5].…”

Electronic devices fabricated at CMOS backend-compatible temperatures

“…Optically active multilayer stacks consisting of silicon nanodots embedded in alumina were processed at temperatures below 325 °C. The investigated low temperature multilayer stacks (Al/TiN/Al 2 O 3 /Si-ND/SiO 2 and Al 2 O 3 /Si-ND/.. /Si-ND/Al 2 O 3 ) have a potential to be used in 3-D integrated memories [37,38,58] and photonic devices [59,60] (discussed in more detail in Chapter 5). …”

“…Due to their high applicability in 3-D memory chip integration, nanodots deposition techniques gain a lot of attention in today's research [37,38].…”

“…To overcome the challenges related to low processing temperatures, several new devices are presently investigated as replacements for the traditional floating gate stack; one of which being the nanocrystal memory cell [36][37][38]74].…”

“…The major benefits provided by the use of a discrete floating gate are the increase of the memory's retention time, an ability to scale the tunnelling oxide thickness, a minimized drain-to-floating-gate coupling and perspective to realize multi-bit storage devices [37]. Additionally, the possibility to fabricate memory cells on re-crystallized amorphous-silicon layers, keeping thereby the total thermal budget of the process low, opens the way to 3-D memory structures inside the microchip's backend.…”