Simultaneous Extraction of Locations and Energies of Two Independent Traps in Gate Oxide From Four-Level Random Telegraph Signal Noise

Abstract

As device size shrinks smaller, random telegraph signal (RTS) noise, which is caused by the trapping and detrapping of a single carrier will become a serious issue. In this paper, we characterized four level RTS and extracted the characteristics of two independent traps. Once the position of the trap is found in the oxide (x T ) and along the channel (y T ) with respect to source, we extracted difference between the oxide conduction band energy (E Cox ) and trap energy (E T ). Finally we introduce eight level RTS observed in some sample which indicates existence of three active traps.

Extraction of Position and Energy Level of Oxide Trap Generating Random Telegraph Noise in 65 nm NOR Flash Memory

“…In the equation above, the Fermi level for electrons is written in terms of Fermi level for holes and channel potential: E Fn (= E Fp −qV C ). In most previous study, V C is approximately expressed as [4][5][6]:…”

“…Several methods were proposed to extract trap location and energy level for MOSFET and Flash memories [4][5][6]. Z. C. Butler consideration of channel surface potential and poly depletion effect in the calculation [5].…”

“…Z. C. Butler consideration of channel surface potential and poly depletion effect in the calculation [5]. B. Oh et al evaluated the Coulomb-blockade effect on trap location extraction [6].…”

Investigation of capture and emission dependence between individual traps from complex random telegraph signal noise analysis

“…There are some cases, however, where complex RTS noise is observed which is caused by more than two traps [9]. Conventionally, capture and emission process of each trap, causing complex RTS noise, are supposed to be independent process [10].…”

“…From this signal, originally, the mean capture ( c ) and emission time ( e ) of two traps are extracted by using the assumption of independent ( Fig. 1(b)) [10]. In this method, the first step is the generation of quantized signal for a current fluctuation by trap1.…”