A statistical model for SILC in flash memories

The reliability of flash memories is strongly. limited by the stress-induced leakage current (SILC), which leads to accelerated charge-loss phenomena in a few anomalous cells. Estimating the reliability of large flash arrays requires that physically-based models for the statistical distribution of SILC are developed. In this paper, we show a physical model for the leakage mechanism in thin oxides, which is able us to explain the anomalous leakage-conduction in tail cells. The physical model is then used for a quantitative evaluation of the SILC distribution in large flash arrays. The new model can reproduce the statistics of SILC for a wide range of tunnel-oxide thickness, and can provide a straightforward estimation of the reliability for large flash arrays.

[1]  D. Ielmini,et al.  Statistical modeling of reliability and scaling projections for flash memories , 2001, International Electron Devices Meeting. Technical Digest (Cat. No.01CH37224).

[2]  D. Ielmini,et al.  Equivalent cell approach for extraction of the SILC distribution in flash EEPROM cells , 2002, IEEE Electron Device Letters.

[3]  Andrea L. Lacaita,et al.  A new two-trap tunneling model for the anomalous stress-induced leakage current (SILC) in Flash memories , 2001 .

[4]  H. Hazama,et al.  Non-uniform current flow through thin oxide after Fowler-Nordheim current stress , 1996, Proceedings of International Reliability Physics Symposium.

[5]  S. Takagi,et al.  A new I-V model for stress-induced leakage current including inelastic tunneling , 1999 .

[6]  R. E. Shiner,et al.  A new reliability model for post-cycling charge retention of flash memories , 2002, 2002 IEEE International Reliability Physics Symposium. Proceedings. 40th Annual (Cat. No.02CH37320).

[7]  C. Hu,et al.  Stress-induced current in thin silicon dioxide films , 1992, 1992 International Technical Digest on Electron Devices Meeting.

[8]  Elyse Rosenbaum,et al.  Mechanism of stress-induced leakage current in MOS capacitors , 1997 .

[9]  Andrea L. Lacaita,et al.  Modeling of SILC based on electron and hole tunneling. I. Transient effects , 2000 .

[10]  Andrea L. Lacaita,et al.  Different types of defects in silicon dioxide characterized by their transient behavior , 2001 .

[11]  Daniele Ielmini,et al.  A new conduction mechanism for the anomalous cells in thin oxide flash EEPROMs , 2001, 2001 IEEE International Reliability Physics Symposium Proceedings. 39th Annual (Cat. No.00CH37167).

[12]  J. Sune,et al.  Post soft breakdown conduction in SiO/sub 2/ gate oxides , 2000, International Electron Devices Meeting 2000. Technical Digest. IEDM (Cat. No.00CH37138).

[13]  Andrea L. Lacaita,et al.  Modeling of SILC based on electron and hole tunneling. II. Steady-state , 2000 .

[14]  M. Ushiyama,et al.  Read-disturb degradation mechanism due to electron trapping in the tunnel oxide for low-voltage flash memories , 1994, Proceedings of 1994 IEEE International Electron Devices Meeting.

[15]  A. Modelli.  Reliability of thin dielectric for non-volatile applications , 1999 .

[16]  R. Shirota,et al.  Extended data retention process technology for highly reliable flash EEPROMs of 10/sup 6/ to 10/sup 7/ W/E cycles , 1998, 1998 IEEE International Reliability Physics Symposium Proceedings. 36th Annual (Cat. No.98CH36173).

[17]  M. Inuishi,et al.  Impact of the two traps related leakage mechanism on the tail distribution of DRAM retention characteristics , 1999, International Electron Devices Meeting 1999. Technical Digest (Cat. No.99CH36318).

[18]  N. Ajika,et al.  Microscopic and statistical approach to SILC characteristics-exponential relation between distributed Fowler Nordheim coefficients and its physical interpretation , 1998, 1998 Symposium on VLSI Technology Digest of Technical Papers (Cat. No.98CH36216).

[19]  Shinichi Takagi,et al.  Experimental evidence of inelastic tunneling in stress-induced leakage current , 1999 .