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

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

The effect of band gap engineering of the nitride storage node on performance and reliability of charge trap flash

The effect of nitride composition, i.e. Si-rich (Si+) and N-rich (N+) nitride bi-layers separated by an oxynitride (SiON) layer on memory performance and reliability is studied. Bottom Si+ layer and top N+ forms the Si+/N+ bi-layer that is compared to the opposite configuration of N+/Si+ bi-layer to reveal large impact on memory performance and reliability. Si+/N+ bi-layers exhibit superior P/E windows and endurance characteristics but worse retention charge loss compared to N+/Si+ stacks. The oxynitride layer composition and position play a dominant role in trap generation as evident from endurance performance. A low energy-threshold degradation mechanism with higher degradation of the SiON layer with greater H-content is observed. A Si-H bond breaking mechanism is proposed as trap generation mechanism during endurance cycling. Retention is primarily bottom nitride composition dependent as tunnel oxide is shown to be the dominant charge loss path

Impact of SiN Composition Variation on SANOS Memory Performance and Reliability Under (FN/FN) Operation

Despite significant advances in structure and material optimization, poor erase (E) speeds and high retention charge loss remain the challenging issues for charge trap Flash (CTF) memories. In this paper, the dependence of SANOS memory performance and reliability on the composition of silicon nitride (SiN) layer is extensively studied. The effect of varying the Si:N ratio on program (P)/E and retention characteristics is investigated. SiN composition is shown to significantly alter the electron and hole trap properties. Varying the SiN composition from N-rich (N(+)) to Si-rich (Si(+)) lowers electron trap depth but increases hole trap depth, causing lower P state saturation but significant over-erase, resulting in an enhanced memory window. During retention, P state charge loss depends on thermal emission followed by the tunneling out of electrons mostly through tunnel dielectric, which becomes worse for Si(+) SiN. Erase state charge loss mainly depends on hole redistribution under the influence of internal electric fields, which improves with Si(+) SiN. This paper identifies several important performances versus reliability tradeoffs to be considered during the optimization of SiN layer composition. It also explores the option for CTF optimization through the engineering of SiN stoichiometry for multilevel cell NAND Flash applications

The effect of band gap engineering of the nitride storage node on performance and reliability of charge trap flash

The effect of nitride composition, i.e. Si-rich (Si+) and N-rich (N+) nitride bi-layers separated by an oxynitride (SiON) layer on memory performance and reliability is studied. Bottom Si+ layer and top N+ forms the Si+/N+ bi-layer that is compared to the opposite configuration of N+/Si+ bi-layer to reveal large impact on memory performance and reliability. Si+/N+ bi-layers exhibit superior P/E windows and endurance characteristics but worse retention charge loss compared to N+/Si+ stacks. The oxynitride layer composition and position play a dominant role in trap generation as evident from endurance performance. A low energy-threshold degradation mechanism with higher degradation of the SiON layer with greater H-content is observed. A Si-H bond breaking mechanism is proposed as trap generation mechanism during endurance cycling. Retention is primarily bottom nitride composition dependent as tunnel oxide is shown to be the dominant charge loss path

Nitride engineering and the effect of interfaces on charge trap flash performance and reliability

The performance and reliability of charge trap flash with single and bi-layer Si-rich and N-rich nitride as the storage node is studied. Single layer devices show lower memory window and poor cycling endurance, and the underlying physical mechanisms for these issues are explained. An engineered trap layer consisting of Si-rich and N-rich nitride interfaced by a SiON barrier layer is proposed. The effect of varying the SiON interfacial layer position on memory window and reliability is investigated. Optimum bi-layer device shows higher memory window and negligible degradation due to cycling (at higher memory window) compared to single layer films. The role of SiON interface in improving the performance and reliability of bi-layer stacks is explained.© IEE

Influence of mastitis metritis agalactia (MMA) on bone and fat metabolism

Mastitis metritis agalactia (MMA) is a common disease in post-partum sows and has a negative effect on sows' longevity as well as on sows' and piglets' health. MMA leads to an inflammatory state. The aim was to investigate the impact of MMA on bone and fat metabolism. The hypothesis was that it is possible to predict MMA by measuring ketone bodies and bone markers. Blood samples from 175 sows were taken within 72 hr after farrowing. Serum was analysed for 25-hydroxyvitamin D (25-(OH)-D), serum crosslaps (CTX-I), osteocalcin (OC), alkaline phosphatase (ALP), calcium (Ca), magnesium (Mg), phosphorus (P), parathyroid hormone (PTH), triglycerides (TG), beta-hydroxybutyric acid (BHB), tumour necrosis factor-alpha (TNF-α) and haptoglobin. Spontaneous urine was collected, and pH value was measured in addition to Ca and P. A proximate analysis of the sows' diets was performed. Age, litter size, body condition score (BCS) and clinical signs of MMA were recorded for each sow. A multivariable logistic regression was undertaken with disease status (MMA or healthy) as the dependent variable. Significance was accepted at p < .05. MMA sows had a poorer BCS (p < .001) in relation to healthy sows. Age and number of piglets did not differ. MMA sows showed increased serum CTX-I (p = .004) and decreased serum OC (p < .001). Concentrations of P (p = .007), activity of ALP (p = .002) and BHB (p = .019) as well as TNF-α (p < .001) and haptoglobin (p = .048) concentrations were increased in MMA sows. No difference in urinary pH value between MMA and healthy sows was found. Our results are in accordance with the known fact that sows are in an extreme catabolic state peripartum. Bone metabolism in MMA sows is much more negatively affected than in healthy sows post-partum, due to inflammatory processes shown by higher concentrations of pro-inflammatory cytokines