Effect of SiN on Performance and Reliability of Charge Trap Flash (CTF) Under Fowler–Nordheim Tunneling Program/Erase Operation

Abstract

Abstract-Silicon-nitride trap layer stoichiometry in charge trap flash (CTF) memory strongly impacts electron and hole trap properties, memory performance, and reliability. Important tradeoffs between program/erase (P/E) levels (memory window), P-and E-state retention loss, and E-state window closure during cycling are shown. Increasing the Si richness of the SiN layer improves memory window, cycling endurance, and E-state retention loss but at the cost of higher P-state retention loss. The choice of SiN stoichiometry to optimize CTF memory performance and reliability is discussed.Index Terms-Charge trap flash (CTF), cycling endurance, program/erase (P/E) window, retention, SANOS, silicon nitride (SiN), SONOS.

Performance and Reliability Study of Single-Layer and Dual-Layer Platinum Nanocrystal Flash Memory Devices Under NAND Operation

“…Ease of integration is the biggest factor in favor of the CTF devices [13]. So far, reported CTF devices have shown good memory window but poor retention [9]- [11]. Large retention loss in CTF devices is related to the shallow depth of Si 3 N 4 bulk traps, which is a fundamental issue related to the nitride material composition and may be difficult to control [9]- [11].…”

“…So far, reported CTF devices have shown good memory window but poor retention [9]- [11]. Large retention loss in CTF devices is related to the shallow depth of Si 3 N 4 bulk traps, which is a fundamental issue related to the nitride material composition and may be difficult to control [9]- [11]. While process integration is a concern, choice of tunable workfunction of the metal NC storage layer is advantageous for achieving good retention, provided an optimal NC area coverage is obtained [15] for good memory window.…”

Performance and Reliability of Au and Pt Single-Layer Metal Nanocrystal Flash Memory Under nand (FN/FN) Operation

“…The difficulty in scaling the tunnel oxide (TO) thickness due to stress-induced leakage-current-related charge loss, reduction in gate coupling, and increase in cell-to-cell interference have made scaling of FG flash difficult at sub-3× node [2]. Nanocrystal (NC) flash [3]- [12] and charge trap flash (CTF) [13], [14] are considered as possible alternatives. CTF devices reported so far show good memory window but poor retention [13], [14], while the NC devices show poor memory window [4], [6], [11], [12].…”

“…Nanocrystal (NC) flash [3]- [12] and charge trap flash (CTF) [13], [14] are considered as possible alternatives. CTF devices reported so far show good memory window but poor retention [13], [14], while the NC devices show poor memory window [4], [6], [11], [12]. Poor retention of CTF is linked to shallow trap depth of the nitride storage layer, which is an inherent material property and is difficult to control [14].…”

“…CTF devices reported so far show good memory window but poor retention [13], [14], while the NC devices show poor memory window [4], [6], [11], [12]. Poor retention of CTF is linked to shallow trap depth of the nitride storage layer, which is an inherent material property and is difficult to control [14]. Choice of tunable workfunction (WF) of the metal-NC storage layer is advantageous for achieving good retention.…”