High leakage current in deep-submicrometer regimes is becoming a significant contributor to power dissipation of CMOS circuits as threshold voltage, channel length, and gate oxide thickness are reduced. Consequently, the identification and modeling of different leakage components is very important for estimation and reduction of leakage power, especially for low-power applications. This paper reviews various transistor intrinsic leakage mechanisms, including weak inversion, drain-induced barrier lowering, gate-induced drain leakage, and gate oxide tunneling. Channel engineering techniques including retrograde well and halo doping are explained as means to manage short-channel effects for continuous scaling of CMOS devices. Finally, the paper explores different circuit techniques to reduce the leakage power consumption.

Leakage current mechanisms and leakage reduction techniques in deep-submicrometer CMOS circuits

A predictive MOSFET model is critical for early circuit design research. To accurately predict the characteristics of nanoscale CMOS, emerging physical effects, such as process variations and correlations among model parameters, must be included. In this paper, a new generation of predictive technology model (PTM) is developed to accomplish this goal. Based on physical models and early-stage silicon data, the PTM of bulk CMOS is successfully generated for 130- to 32-nm technology nodes, with an Leff of as low as 13 nm. The accuracy of PTM predictions is comprehensively verified: The error of I on is below 10% for both n-channel MOS and p-channel MOS. By tuning only ten primary parameters, the PTM can be easily customized to cover a wide range of process uncertainties. Furthermore, the new PTM correctly captures process sensitivities in the nanometer regime, particularly the interactions among Leff, Vth, mobility, and saturation velocity. A website has been established for the release of PTM: http://www.eas.asu.edu/~ptm

New Generation of Predictive Technology Model for Sub-45 nm Early Design Exploration

Predictive MOSFET model is critical for early circuit design research. To accurately predict the characteristics of nanoscale CMOS, emerging physical effects, such as process variations and physical correlations among model parameters, must be included. In addition, predictions across technology generations should be smooth to make continuous extrapolations. In this work, a new generation of predictive technology model (PTM) is developed to accomplish these goals. Based on physical models and early stage silicon data, PTM of bulk CMOS for 130nm to 32nm technology nodes is successfully generated. By tuning ten parameters, PTM can be easily customized to cover a wide range of process uncertainties. The accuracy of PTM predictions is comprehensively verified: for NMOS, the error of I/sub on/ is 2% and for PMOS, it is 5%. Furthermore, the new PTM correctly captures process sensitivities in the nanometer regime. A webpage has been established for the release of PTM (http://www.eas.asu.edu//spl sim/ptm).

New Generation of Predictive Technology Model for Sub-45nm Design Exploration

A predictive MOSFET model is critical for early circuit design research. In this work, a new generation of Predictive Technology Model (PTM) is developed, covering emerging physical effects and alternative structures, such as the double-gate device (i.e., FinFET). Based on physical models and early stage silicon data, PTM of bulk and double-gate devices are successfully generated from 130nm to 32nm technology nodes, with effective channel length down to 13nm. By tuning only ten primary parameters, PTM can be easily customized to cover a wide range of process uncertainties. The accuracy of PTM predictions is comprehensively verified with published silicon data: the error of the current is below 10p for both NMOS and PMOS. Furthermore, the new PTM correctly captures process sensitivities in the nanometer regime. PTM is available online at http://www.eas.asu.edu/~ptm.

Predictive technology model for nano-CMOS design exploration

Technology scaling demands a decrease in both V/sub dd/ and V/sub t/ to sustain historical delay reduction, while restraining active power dissipation. Scaling of V/sub t/ however leads to substantial increase in the sub-threshold leakage power and is expected to become a considerable constituent of the total dissipated power. It has been observed that the stacking of two off devices has smaller leakage current than one off device. In this paper we present a model that predicts the scaling nature of this leakage reduction effect. Device measurements are presented to prove the model's accuracy. Use of stack effect for leakage reduction and other implications of this effect are discussed.

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Scaling of stack effect and its application for leakage reduction

A leading edge 130 nm generation logic technology with 6 layers of dual damascene Cu interconnects is reported. Dual Vt transistors are employed with 1.5 nm thick gate oxide and operating at 1.3 V. High Vt transistors have drive currents of 1.03 mA//spl mu/m and 0.5 mA//spl mu/m for NMOS and PMOS respectively, while low Vt transistors have currents of 1.17 mA//spl mu/m and 0.6 mA//spl mu/m respectively. Technology design rules allow a 6-T SRAM cell with an area of 2.45 /spl mu/m/sup 2/, while array specific design rule give the densest SRAM reported to date, the 6-T cell has an area of only 2.09 /spl mu/m/sup 2/. Excellent yield and performance is demonstrated on a 18 Mbit CMOS SRAM.

T. Bramblett

Papers

A 130 nm generation logic technology featuring 70 nm transistors, dual Vt transistors and 6 layers of Cu interconnects