Poly-Silicon Trap Position and Pass Voltage Effects on RTN Amplitude in a Vertical NAND Flash Cell String

We investigate the dependence of random telegraph noise (RTN) on a poly-silicon trap position in a 3D vertical channel and charge-trapping NAND flash cell string. We characterize RTN in read current of each cell of a string at different read and pass voltages. RTN characteristics resulting from a trap in a read cell or in a pass cell are differentiated. A method to identify a poly-silicon trap position in a NAND string is proposed. We perform the 3D TCAD simulation to calculate channel electron density in a string. Measured RTN characteristics can be explained by current-path percolation and channel carrier screening effects. The distribution of RTN amplitudes in NAND strings is characterized.

[1]  A.L. Lacaita,et al.  Statistical Model for Random Telegraph Noise in Flash Memories , 2008, IEEE Transactions on Electron Devices.

[2]  Chih-Yuan Lu,et al.  Program Trapped-Charge Effect on Random Telegraph-Noise Amplitude in a Planar SONOS Flash Memory Cell , 2009, IEEE Electron Device Letters.

[3]  Dong Woo Kim,et al.  Vertical cell array using TCAT(Terabit Cell Array Transistor) technology for ultra high density NAND flash memory , 2006, 2009 Symposium on VLSI Technology.

[4]  Y. Iwata,et al.  Optimal Integration and Characteristics of Vertical Array Devices for Ultra-High Density, Bit-Cost Scalable Flash Memory , 2007, 2007 IEEE International Electron Devices Meeting.

[5]  R. Degraeve,et al.  Characterizing grain size and defect energy distribution in vertical SONOS poly-Si channels by means of a resistive network model , 2013, 2013 IEEE International Electron Devices Meeting.

[6]  Andrew R. Brown,et al.  RTS amplitudes in decananometer MOSFETs: 3-D simulation study , 2003 .

[7]  R. Degraeve,et al.  Statistical spectroscopy of switching traps in deeply scaled vertical poly-Si channel for 3D memories , 2013, 2013 IEEE International Electron Devices Meeting.

[8]  P.K. Ko,et al.  Random telegraph noise of deep-submicrometer MOSFETs , 1990, IEEE Electron Device Letters.

[9]  Chilhee Chung,et al.  Intrinsic fluctuations in Vertical NAND flash memories , 2012, 2012 Symposium on VLSI Technology (VLSIT).

[10]  J. Rubí,et al.  Theory of surface noise under Coulomb correlations between carriers and surface states , 2002 .

[11]  K. Otsuga,et al.  The Impact of Random Telegraph Signals on the Scaling of Multilevel Flash Memories , 2006, 2006 Symposium on VLSI Circuits, 2006. Digest of Technical Papers..