The Impact of Dennard's Scaling Theory - IEEE

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5 IEEE SSCS Society Memberships Options All prices are quoted in US dollars. Please check (✓) appropriate boxes. 6 PERSONAL INFORMATION Were You Referred to IEEE? Complete both sides of this form, sign and return to: IEEE Admission and Advancement 445 Hoes Lane, PO Box 6804 Piscataway, NJ 08855-6804 USA or fax to +1 732 981 0225 or join online at sscs.org/join Please reprint your name here TRACKING CODE BETWEEN 16 AUG 2006- 28 FEB 2007 PAY FULL YEAR IEEE Journal of Solid-State Circuits Print (Airfreight: Add $74) 37-4101 22.00 ■ 11.00 ■ Freq 12x/yr IEEE Solid-State Circuits Digital Archive New Reduced Subscription Rate Includes 2 DVDs 37-281D 40.00 ■ 40.00 ■ Freq 1x/yr (shipped in March) Display Technology, IEEE/OSA Journal of Print (Airfreight: Add $38) 037-2021 28.00 ■ 14.00 ■ Electronic 037-202E 26.00 ■ 13.00 ■ Print & Electronic Combination 037-8-03P 39.00 ■ 20.00 ■ Freq 4x/yr Semiconductor Manufacturing, IEEE Trans. on Print & Electronic Combination (Airfreight: Add $38) Freq 4x/yr 37-767P 16.00 ■ 8.00 ■ IEEE Sensors Journal Print (Airfreight: Add $34) 500-1861 33.00 ■ 16.50 ■ Electronic 500-186E 25.00 ■ 12.50 ■ Print & Electronic Combination 500-734P 46.00 ■ 23.00 ■ Freq 6x/yr Very Large Scale Integration Systems, IEEE Trans. on Print/Electronic (Airfreight: Add $42) 37-769P 28.00 ■ 14.00 ■ Freq 12x/yr Electronic subscriptions can be accessed at ieeexplore.ieee.org ■ Yes ■ No If yes, provide the following: Member Recruiter Name____________________________________ IEEE Recruiter’s Member Number (Required)_____________________ Students, please join us online! .....www.ieee.org/students Renewing Members ......................... .www.ieee.org/renewal All electronic subscriptions ..........www.ieee.org/ieeexplore PROMO CODE BETWEEN 1 MAR 2007- 15 AUG 2007 PAY HALF YEAR 7 8 9 2007 IEEE SSCS Membership Rates Please check (✓) one appropriate box. A. B. IEEE MEMBER ADDING SSCS ONLY .....$20.00 ■ ......$10.00 ■ C. D. IEEE member dues and regional assessments are based on where you live and when you apply. Membership is based on the calendar year from 1 January through 31 December. RESIDENCE United States ..........................................$181.00 ■ ......$90.50 ■ Canada (includes GST)* ..........................$169.38 ■ ......$84.69 ■ Canada (includes HST)* ..........................$179.22 ■ ......$89.61 ■ Africa, Europe, Middle East ....................$154.00 ■ ......$77.00 ■ Latin America ..........................................$147.00 ■ ......$73.50 ■ Asia, Pacific .............................................$148.00 ■ ......$74.00 ■ *IEEE Canada Business No. 125634188 IEEE Member Number if adding SSCS only ____________________________________ SSCS AFFILIATE MEMBERSHIP ..............$82.00 ■ ......$41.00 ■ Affiliation with the IEEE Solid-State Circuits Society is open to non-IEEE technical professionals who belong to another scientific/technical society. SSCS affiliates pay the Society’s annual membership dues and an annual affiliate fee. All SSCS affiliate benefits and services come directly from the Society. ▼ Affiliation Requirement More Recommended Options Proceedings of the IEEE ........... print $30.00 ■ or Payment Amount Name as it appears on card Signature online $30.00 ■ Proceedings of the IEEE (print/online combination) ........... $39.00 ■ IEEE Standards Association (IEEE-SA) ................................ $37.00 ■ IEEE Women in Engineering (WIE) ..................................... $25.00 ■ Please total the IEEE Society Membership dues and other amounts from this page: IEEE SSCS Membership dues 7 .................................... $ ______ Optional Subscriptions 5 .............................................. $ ______ IEEE-SA/WIE dues (optional) 8 ...................................... $ ______ Proceedings of the IEEE (optional) 8 .............................. $ ______ Canadian residents pay 7% GST or 15% HST Reg no. 125634188 on Society payments & publications only ..................TAX $ ______ AMOUNT PAID ......................................................... TOTAL $ ______ Payment Method All prices are quoted in US dollars. You may pay for IEEE membership by credit card (see below), check or money order payable to IEEE, drawn on a US bank. ■ Check ■ i ■ [ ■ ■ w Credit Card Number MONTH YEAR EXPIRATION DATE BETWEEN 16 AUG 2006- 28 FEB 2007 PAY Name of non-IEEE scientific/technical Society Exp. Yr. MINIMUM INCOME OR UNEMPLOYED PROVISION Applicants who certify that their prior year income did not exceed US$12,300 (or equivalent) or were not employed are granted 50% reduction in: full year dues, regional assessment and fees for one IEEE Society. If applicable, please check appropriate box and adjust payment accordingly. Student members are not eligible. ■ I certify I earned less than US$12,300 in 2005 ■ I certify that I was unemployed in 2005 CARDHOLDER’S 5-DIGIT ZIPCODE (BILLING STATEMENT ADDRESS) USA ONLY BETWEEN 1 MAR 2007- 15 AUG 2007 PAY
processing, the boron is redistributed as shown by the heavier dashed line. These predicted profiles were obtained using a computer program developed by F. F. Morehead of our laboratories. The program assumes that boron atoms diffusing in the silicon reflect from the silicon-oxide interface and thereby raise the surface concentration. For modeling purposes it is convenient to use a simple, idealized, stepfunction representation of the doping profile, as shown by the solid line in Fig. 5. The step profile approximates the final predicted profile rather well and offers the advantage that it can be described by a few simple parameters. The three profiles shown in Fig. 5 all have the same active dose. Using the step profile, a model for determining threshold voltage has been developed from piecewise solutions of Poisson’s equation with appropriate boundary conditions [11]. The one-dimensional model considers only the vertical dimension and cannot account for horizontal short-channel effects. Results of the model are shown in Fig, 6 which plots the threshold voltage versus source-to-substrate bias for the ionimplanted step profile shown in Fig. 5. For comparison, Fig. 6 also shows the substrate sensitivity characteristics for the nonimplanted device with a 200-Å gate insulator and a constant background doping, and for a hypothetical device having a 350-Å gate insulator like the implanted structure and a constant background doping like the nonimplanted structure. Fig. 6. Calculated and experimental substrate sensitivity characteristics for non-implanted devices with 200- and 350-Å gate insulators, and for corresponding ion-implanted device with 350-Å gate insulator. The nonimplanted 200-Å case exhibits a low substrate sensitivity, but the magnitude of the threshold voltage is also low. On the other hand, the nonimplanted 350- Å case shows a higher threshold, but with an undesirably high substrate sensitivity. The ion-implanted case offers both a sufficiently high threshold voltage TECHNICAL ARTICLES and a reasonably low substrate sensitivity, particularly for Vs−sub ≥ 1 V. For Vs−sub < 1 V, a steep slope occurs because the surface inversion layer in the channel is obtained while the depletion region in the silicon under the gate does not exceed D, the step width of the heavier doped implanted region. For Vs−sub ≥ 1 V, at inversion the depletion region now extends into the lighter doped substrate and the threshold voltage then increases relatively slowly with Vs−sub [11]. Thus, with a fixed substrate bias of -1 V, the substrate sensitivity over the operating range of the source voltage (e.g., ground potential to 4 V) is reasonably low and very similar to the slope of the nonimplanted 200-Å design. However, the threshold voltage is significantly higher for the implanted design which allows adequate design margin so that, under worst case conditions (e.g., short-channel effects which reduce the threshold considerably), the threshold will still be high enough so that the device can be turned off to a negligible conduction level as required for dynamic memory applications. Experimental results are also given in Fig. 6 from measurements made on relatively long devices (i.e., L = 10μ) which have no short-channel effects. These data agree reasonably well with the calculated curve. A 35 keV, 6 × 10 11 atoms/cm 2 implant was used to achieve this result, rather than the slightly higher design value of 40 keV and 6.7 × 10 11 atoms/cm 2 . TWO-DIMENSIONAL (SHORT CHANNEL) ANALYSIS For devices with sufficiently short-channel lengths, the one-dimensional model is inadequate to account for the threshold voltage lowering due to penetration of the drain field into the channel region normally controlled by the gate. While some models have been developed which account for this behavior [14], the problem is complicated for the ion-implanted structure by the non-uniform doping profile which leads to an electric field pattern that is difficult to approximate. For the ion-implanted case, the two-dimensional numerical current transport model of Kennedy and Mock [15], [16] was utilized. The computer program was modified by W. Chang and P. Hwang [17] to handle the abrupt substrate doping profiles considered for these devices. The numerical current transport model was used to calculate the turn-on behavior of the ionimplanted device by a point-by-point computation of the device current for increasing values of gate voltage. Calculated results are shown in Fig. 7 for two values of channel length in the range of 1μ, as well as for a relatively long-channel device with L = 10μ. All cases were normalized to a width-to-length ratio of unity, and a drain voltage of 4 V was used in all cases. As the channel length Winter 2007 IEEE SSCS NEWSLETTER 43
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Page 17 and 18: y circuit designers. One of the key
Page 19 and 20: Recollections on MOSFET Scaling By
Page 21 and 22: try settled on 5V supplies in the e
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Page 27 and 28: 10. References 1. G.E. Moore, “Pr
Page 29 and 30: Fig. 2. Schematic of a CMOS device
Page 31 and 32: The largest question in the early t
Page 33 and 34: It’s All About Scale Hans Stork,
Page 35 and 36: cell phone. With many fundamental p
Page 37 and 38: The one-dimensional threshold model
Page 39 and 40: Fig. 1. Illustration of device scal
Page 41 and 42: Fig. 3. Experimental turn-on charac
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