Evidence for two types of radiation-induced trapped positive charge

Abstract

New experimental evidence is presented that supports a model that assumes two distinguishable types of positive oxide charge following x-irradiation. Two new experiments have been performed designed to separate the annealing properties of the two types of trapped positive charge. It is found that one type of trapped positive charge can be permanently removed at room temperature using substrate hot electron injection. The second type of trapped positive charge is found to be stable at temperatures up to 160°C

Influence of Ionizing Radiation and Hot Carrier Injection on Metal-Oxide-Semiconductor Transistors

“…It has been observed that during annealing part of trapped charge is permanently burnt-in (neutralized), while the other part may only be compensated, which leads to the effect of "inverse burn-in" (apparent increase in the density of trapped charge during annealing at gate negative polarization), which is attributed, by a group of authors, to the existence of the so-called Switching Oxide Trap (SOT) centres [77,78]. Another group of authors attribute it to the existence of the so-called Anomalous Positive Charge (APC) centres [24,79,80]. Both groups explain inverse burn-in by the exchange of charge with substrate whereby such exchange, in case of SOT, is performed by electron tunnelling as the appropriate levels of these centres lay at the height of the substrate conductive zone [78], while APC are, similarly to interface traps, capable of performing direct exchange with the substrate as their energy levels are at the level of the forbidden zone [24,79,80].…”

“…MOS components annealing may be performed spontaneously (in air atmosphere, at room temperature, without polarization), or at lowered or elevated temperatures, or in the presence of various intensity and direction electric field. A number of experimental results [24,[74][75][76][77][78][79][80] have shown that the density of interface traps during annealing mainly does not change, while the density of trapped charge in the oxide decreases. Several models are proposed for the trapped charge annealing [75,77].…”

“…Another group of authors attribute it to the existence of the so-called Anomalous Positive Charge (APC) centres [24,79,80]. Both groups explain inverse burn-in by the exchange of charge with substrate whereby such exchange, in case of SOT, is performed by electron tunnelling as the appropriate levels of these centres lay at the height of the substrate conductive zone [78], while APC are, similarly to interface traps, capable of performing direct exchange with the substrate as their energy levels are at the level of the forbidden zone [24,79,80]. Regardless of their different approaches, both groups have practically contributed to establishing the fact that SOT and APC are most probably the same centre, i.e.…”

Radiation resistance of flash memory manufactured in deep-submicron technology

“…Switching Oxide Trap (SOT) centara [192,193], a druga postojanju tzv. Anomalous Positive Charge (APC) centara [139,194,195]. Obe grupe su inverzno odžarivanje objašnjavale razmenom naelektrisanja sa supstratom, pri čemu se ona u slučaju SOT vrši tunelovanjem elektrona, jer odgovarajući energetski nivoi ovih centara leže u visini provodne zone supstrata [193], dok su APC u mogućnosti, da slično površinskim stanjima, vrše direktnu razmenu naelektrisanja sa supstratom, jer su njihovi energetski nivoi u visini zabranjene zone [139,194,195].…”

“…Anomalous Positive Charge (APC) centara [139,194,195]. Obe grupe su inverzno odžarivanje objašnjavale razmenom naelektrisanja sa supstratom, pri čemu se ona u slučaju SOT vrši tunelovanjem elektrona, jer odgovarajući energetski nivoi ovih centara leže u visini provodne zone supstrata [193], dok su APC u mogućnosti, da slično površinskim stanjima, vrše direktnu razmenu naelektrisanja sa supstratom, jer su njihovi energetski nivoi u visini zabranjene zone [139,194,195]. Bez obzira na razliku u pristupu, ustanovljeno je da su SOT i APC najverovatnije isti centri zahvata, i to centri E' tipa, koji u zavisnosti od uslova eksperimenta i merenja mogu da ispolje različita svojstva (odžarivanje, inverzno odžarivanje ili razmenu naelektrisanja).…”