Tunneling leakage current in ultrathin (<4 nm) nitride/oxide stack dielectrics

The leakage current in high-quality ultrathin silicon nitride/oxide (N/O) stack dielectric is calculated based on a model of one-step electron tunneling through both the nitride and the oxide layers. The results show that the tunneling leakage current in the N/O stack is substantially lower than that in the oxide layer of the same equivalent oxide thickness (EOT). The theoretical leakage current in N/O stack has been found to be a strong function of the nitride/oxide EOT ratio: in the direct tunneling regime, the leakage current decreases monotonically as the M/O ratio increases, while in the Fowler-Nordheim regime the lowest leakage current is realized with a N/O EOT ratio of 1:1. Due to the asymmetry of the N/O barrier shape, the leakage current under substrate injection is higher than that under gate injection, although such a difference becomes smaller in the lower voltage regime. Experimental data obtained from high quality ultrathin N/O stack dielectrics agree well with calculated results.

[1]  J. Hauser,et al.  Ultrathin oxide-nitride gate dielectric MOSFET's , 1998, IEEE Electron Device Letters.

[2]  D. Frohman-Bentchkowsky,et al.  Charge Transport and Storage in Metal‐Nitride‐Oxide‐Silicon (MNOS) Structures , 1969 .

[3]  K. K. Young,et al.  Charge transport and trapping characteristics in thin nitride-oxide stacked films , 1988, IEEE Electron Device Letters.

[4]  T. Morimoto,et al.  An improvement of hot-carrier reliability in the stacked nitride-oxide gate n- and p-MISFET's , 1995 .

[5]  T. P. Ma,et al.  Making Silicon Nitride Film a Viable Gate Dielectric , 1998 .

[6]  Yutaka Hayashi,et al.  Carrier conduction and trapping in metal‐nitride‐oxide‐semiconductor structures , 1982 .

[7]  Y. Taur,et al.  Quantum-mechanical modeling of electron tunneling current from the inversion layer of ultra-thin-oxide nMOSFET's , 1997, IEEE Electron Device Letters.

[8]  Simon M. Sze,et al.  Current Transport and Maximum Dielectric Strength of Silicon Nitride Films , 1967 .

[9]  J. Simmons.  Generalized Formula for the Electric Tunnel Effect between Similar Electrodes Separated by a Thin Insulating Film , 1963 .

[10]  X. W. Wang,et al.  Highly Reliable Silicon Nitride Films Made by Jet Vapor Deposition , 1994 .

[11]  D. Kwong,et al.  Ultra thin (<3 nm) high quality nitride/oxide stack gate dielectrics fabricated by in-situ rapid thermal processing , 1997, International Electron Devices Meeting. IEDM Technical Digest.

[12]  T. P. Ma,et al.  Ultra-thin Nitride/oxide Stack Dielectric Produced By In-situ Jet Vapor Deposition , 1997, Proceedings of Technical Papers. International Symposium on VLSI Technology, Systems, and Applications.

[13]  X. W. Wang,et al.  Highly Reliable Silicon Nitride Thin Films Made by Jet Vapor Deposition , 1995 .

[14]  D. Schroder,et al.  Characterization of current transport in MNOS structures with complementary tunneling emitter bipolar transistors , 1979, IEEE Transactions on Electron Devices.