The impact of high-/spl kappa/ gate dielectrics and metal gate electrodes on sub-100 nm MOSFETs

The potential impact of high-/spl kappa/ gate dielectrics on device short-channel performance is studied over a wide range of dielectric permittivities using a two-dimensional (2-D) simulator implemented with quantum mechanical models. It is found that the short-channel performance degradation is caused by the fringing fields from the gate to the source/drain regions. These fringing fields in the source/drain regions further induce electric fields from the source/drain to channel which weakens the gate control. The gate dielectric thickness-to-length aspect ratio is a proper parameter to quantify the percentage of the fringing field and thus the short channel performance degradation. In addition, the gate stack architecture plays an important role in the determination of the device short-channel performance degradation. Using double-layer gate stack structures and low-/spl kappa/ dielectric as spacer materials can well confine the electric fields within the channel thereby minimizing short-channel performance degradation. The introduction of a metal gate not only eliminates the poly gate depletion effect, but also improves short-channel performance. Several approaches have been proposed to adjust the proper threshold voltage when midgap materials or metal gates are used.

[1]  H. Iwai,et al.  1.5 nm direct-tunneling gate oxide Si MOSFET's , 1996 .

[2]  Jeong-Mo Hwang,et al.  Novel polysilicon/TiN stacked-gate structure for fully-depleted SOI/CMOS , 1992, 1992 International Technical Digest on Electron Devices Meeting.

[3]  Y. Taur,et al.  Modeling and Characterization of n+- and p+-Polysilicon-Gated Ultra Thin Oxides (21-26 A) , 1997 .

[4]  D. Hwang,et al.  Stacked gate dielectrics with TaO for future CMOS technologies , 1998, 1998 Symposium on VLSI Technology Digest of Technical Papers (Cat. No.98CH36216).

[5]  Eric M. Vogel,et al.  Modeled tunnel currents for high dielectric constant dielectrics , 1998 .

[6]  P. Woerlee,et al.  A simple model for quantisation effects in heavily-doped silicon MOSFETs at inversion conditions , 1994 .

[7]  Han,et al.  Modeling And Characterization Of N/sup +/- And P/sup +/-polysilicon-gated Ultra Thin Oxides (21-26 /spl Aring/) , 1997, 1997 Symposium on VLSI Technology.

[8]  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.

[9]  Tadahiro Ohmi,et al.  Reliable tantalum-gate fully-depleted-SOI MOSFET technology featuring low-temperature processing , 1997 .

[10]  C. Hu Gate oxide scaling limits and projection , 1996 .

[11]  Donggun Park,et al.  Leakage current comparison between ultra-thin Ta2O5 films and conventional gate dielectrics , 1998, IEEE Electron Device Letters.

[12]  J. Autran,et al.  Properties of amorphous and crystalline Ta2O5 thin films deposited on Si from a Ta(OC2H5)5 precursor , 1998 .

[13]  Ming-Ta Hsieh,et al.  MOSFET transistors fabricated with high permitivity TiO/sub 2/ dielectrics , 1997 .

[14]  Zhiping Yu,et al.  Design considerations of high-/spl kappa/ gate dielectrics for sub-0.1-/spl mu/m MOSFET's , 1999 .

[15]  Jason C. S. Woo,et al.  Gate Stack Architecture Analysis and Channel Engineering in Deep Sub-Micron MOSFETs , 1999 .