Papers by Sriram Balasubramanian
Energy-delay optimization of thin-body MOSFETs for the sub-15 nm regime
2004 IEEE International SOI Conference (IEEE Cat. No.04CH37573), 2004
Energy-Delay Optimization of Thin-Body MOSFETs for the Sub-15 nm Regime Sriram Balasubramanian, J... more Energy-Delay Optimization of Thin-Body MOSFETs for the Sub-15 nm Regime Sriram Balasubramanian, Joshua L. Garrett, Varadarajan Vidya, Borivoje NikoliC, and Tsu-Jae King Deparhnent of Electrical Engineering and Computer Sciences, University of Califmia, ...
Fin Sidewall Microroughness Measurement by AFM
MRS Proceedings, 2004
WireFET Technology for 3-D Integrated Circuits
2006 International Electron Devices Meeting, 2006
A novel method to fabricate a transistor directly within a wire is presented. The phenomenon of a... more A novel method to fabricate a transistor directly within a wire is presented. The phenomenon of aluminum-induced crystallization of silicon is used to embed crystalline Si regions within an aluminum wire, enabling FETs to be fabricated directly within interconnects. The wireFET fabrication process is relatively simple, does not require unconventional materials or processing methods, and has low associated thermal budget
The silicon-based microelectronics industry has been growing rapidly for the past four decades fo... more The silicon-based microelectronics industry has been growing rapidly for the past four decades following Moore's law of scaling. However, fundamental physical limits have heralded the end of conventional linear scaling of transistor dimensions, and a new era of MOSFET scaling constrained by power dissipation and process-induced variations is already here. Fundamental changes in device architecture may be necessary to continue scaling trends with thin-body MOSFETs such as UTB-FETs and FinFETs emerging as leading contenders. This dissertation has addressed many of the key scaling issues involved in the design and performance optimization of thin-body MOSFETs, and highlights applications that take advantage of these projected benefits.
Semiconductor Device and Method of Fabrication
FinFET-based SRAM design
Proceedings of the 2005 international symposium on Low power electronics and design - ISLPED '05, 2005
Intrinsic variations and challenging leakage control in today&amp... more Intrinsic variations and challenging leakage control in today's bulk-Si MOSFETs limit the scaling of SRAM. Design tradeoffs in six-transistor (6-T) and four-transistor (4-T) SRAM cells are presented in this work. It is found that 6-T and 4-T FinFET-based SRAM cells designed with built-in feedback achieve significant improvements in the cell static noise margin (SNM) without area penalty. Up to 2x
Semiconductor device and method of fabrication
Finfet-based sram with feedback
Circuit-Performance Implications for Double-Gate MOSFET Scaling below 25 nm
Circuit-performance implications for double-gate MOSFET scaling in the sub-25 nm gate length regi... more Circuit-performance implications for double-gate MOSFET scaling in the sub-25 nm gate length regime are investigated. The optimal gate-to-source/drain overlap needed to maximize drive current is found to be different than that needed to minimize FO-4 inverter delay due to parasitic capacitances. It is concluded that the effective channel length must be slightly larger than the physical gate length in order to achieve optimal circuit performance.
IEEE Transactions on Very Large Scale Integration (VLSI) Systems, 2000
Process-induced variations and sub-threshold leakage in bulk-Si technology limit the scaling of S... more Process-induced variations and sub-threshold leakage in bulk-Si technology limit the scaling of SRAM into sub-32 nm nodes. New device architectures are being considered to improve control and reduce short channel effects. Among the likely candidates, FinFETs are the most attractive option because of their good scalability and possibilities for further SRAM performance and yield enhancement through independent gating. The enhancements to read/write margins and yield are investigated in detail for two cell designs employing independently gated FinFETs. It is shown that FinFET-based 6-T SRAM cells designed with pass-gate feedback (PGFB) achieve significant improvements in the cell read stability without area penalty. The write-ability of the cell can be improved through the use of pull-up write gating (PUWG) with a separate write word line (WWL). The benefits of these two approaches are complementary and additive, allowing for simultaneous read and write yield enhancements when the PGFB and PUWG designs are used in combination.
IEEE Transactions on Electron Devices, 2000
Forward body biasing is a promising approach for realizing optimum threshold-voltage (V TH ) scal... more Forward body biasing is a promising approach for realizing optimum threshold-voltage (V TH ) scaling in the era when gate dielectric thickness can no longer be scaled down. This is confirmed experimentally and by simulation of a 10-nm gate length MOSFET. Because forward body bias (V F ) decreases the depletion width (X DEP ) in the channel region, it reduces V TH rolloff significantly. MOSFET performance is maximized under forward body bias with steep retrograde channel doping, and such channel doping profiles are required to accomplish good shortchannel behavior (small X DEP ) at low V TH notwithstanding body bias; therefore, the combination of forward body biasing with steep retrograde channel doping profile can extend the scaling limit of conventional bulk-Si CMOS technology to 10-nm gate length MOSFET. Considering forward biased p-n junction current, parasitic bipolar transistor, and CMOS latch-up phenomena, the upper limit for |V F | should be set at 0.6-0.7 V, which is sufficient to realize significant advantages of forward body biasing.
IEEE Electron Device Letters, 2000
Forward body biasing is a solution for continued scaling of bulk-Si CMOS technology. In this lett... more Forward body biasing is a solution for continued scaling of bulk-Si CMOS technology. In this letter, the dependence of 30-nm-gate MOSFET performance on body bias is experimentally evaluated for devices with various channel-doping profiles to provide guidance for channel engineering in a forward body-biasing scheme. Furthermore, simulations of 10-nm-gate CMOS (hp22-nm node) devices are performed to study the optimal channel-doping profile and gate work function engineering for a forward biasing scheme.
IEEE Electron Device Letters, 2000
Active threshold voltage V TH control via wellsubstrate biasing can be utilized to satisfy Intern... more Active threshold voltage V TH control via wellsubstrate biasing can be utilized to satisfy International Roadmap for Semiconductors performance and standby power requirements for CMOS technology beyond the hp65-nm node. In this letter, the impact of substrate bias V SUB on hot-carrier reliability is presented. The impact varies with the gate length and body effect factor. These findings are explained, and the effects of future scaling are discussed using a quasi-two-dimensional model. Significant and important improvement in hot-carrier lifetime with forward-bias V SUB can be expected for deeply scaled CMOS devices, making it an attractive method for extending the scalability of bulk-Si transistor technology.
FinFET SRAM with enhanced read/write margins
International SOI …, 2006
In this work, the impact of this pass-gate feedback (PGFB) technique on cell write-ability is exa... more In this work, the impact of this pass-gate feedback (PGFB) technique on cell write-ability is examined, and gate workfunction (Phi m) tuning for optimization of the trade-off with read margin is discussed. To further improve cell write-ability, the p-channel pull-up ...
Circuit-performance implications for double-gate MOSFET scaling below 25 nm
Circuit-performance implications for double-gate MOSFET scaling in the sub-25 nm gate length regi... more Circuit-performance implications for double-gate MOSFET scaling in the sub-25 nm gate length regime are investigated. The optimal gate-to-source/drain overlap needed to maximize drive current is found to be different than that needed to minimize FO-4 inverter delay due to parasitic capacitances. It is concluded that the effective channel length must be slightly larger than the physical gate length in order to achieve optimal circuit performance.
The effect of pretensioning and age on torso rollout in restrained human volunteers in far-side lateral and oblique loading
Stapp Car Crash Journal, Oct 1, 2012
Far-side side impact loading of a seat belt restrained occupant has been shown to lead to torso s... more Far-side side impact loading of a seat belt restrained occupant has been shown to lead to torso slip out of the shoulder belt. A pretensioned seat belt may provide an effective countermeasure to torso rollout; however the effectiveness may vary with age due to increased flexibility of the pediatric spine compared to adults. To explore this effect, low-speed lateral (90°) and oblique (60°) sled tests were conducted using male human volunteers (20 subjects: 9-14 years old, 10 subjects: 18-30 years old), in which the crash pulse safety envelope was defined from an amusement park bumper-car impact. Each subject was restrained by a lap and shoulder belt system equipped with an electromechanical motorized seat belt retractor (EMSR) and photo- reflective targets were attached to a tight-fitting headpiece or adhered to the skin overlying key skeletal landmarks. Each subject was randomly assigned to either the 60° or 90° direction and was exposed to 4 test conditions - arms up (with hands on their knees) with EMSR on, arms down (with hands low on the hips) with EMSR on, arms up with EMSR off, arms down with EMSR off. The effect of age and pretensioning on the following outcomes was quantified: 1) lateral and forward displacement of the torso, 2) torso rollout angle projected onto three orthogonal planes, and 3) resultant belt-sternal distance. The effect of pretensioning on torso containment within the shoulder belt was strong in both impact directions across all metrics evaluated. EMSR activation significantly reduced lateral displacement of the suprasternal notch (~100 mm, p<0.0001), coronal projection of the torso rollout angle (~15°, p<0.0001), and belt sternal distance when the arms were down (~50 mm, p<0.05). The benefit of pretensioning was achieved by early engagement of the torso by the shoulder belt. An added benefit of pretensioning was the ability to make similar the torso kinematics across a range of anthropometries as assessed within and across age groups. These results can serve as a data set for validating the responses of restrained ATDs and computational human models to low severity far side collisions, in particular the interaction between the torso and the shoulder belt.
A Phase II Multicenter Study of the Histone Deacetylase Inhibitor (HDACi) Abexinostat (PCI-24781) in Relapsed/Refractory Follicular Lymphoma (FL) and Mantle Cell Lymphoma (MCL)
Ash Annual Meeting Abstracts, Nov 16, 2012
Annals of Advances in Automotive Medicine Annual Scientific Conference Association For the Advancement of Automotive Medicine Association For the Advancement of Automotive Medicine Scientific Conference, 2010
The Hybrid III 6-year-old ATD has been benchmarked against adult-scaled component level tests but... more The Hybrid III 6-year-old ATD has been benchmarked against adult-scaled component level tests but the lack of biomechanical data hinders the effectiveness of the procedures used to scale the adult data to the child. Whole body kinematic validation of the pediatric ATD through limited comparison to post mortem human subjects (PMHS) of similar age and size has revealed key differences attributed to the rigidity of the thoracic spine. As restraint systems continue to advance, they may become more effective at limiting peak loads applied to occupants, leading to lower impact environments for which the biofidelity of the ATD is not well established. Consequently, there is a growing need to further enhance the assessment of the pediatric ATD by evaluating its biofidelity at lower crash speeds. To this end, this study compared the kinematic response of the Hybrid III 6 year old ATD against size-matched male pediatric volunteers (PVs) (6-9 yrs) in low-speed frontal sled tests. A 3-D near-infrared target tracking system quantified the position of markers at seven locations on the ATD and PVs (head top, opisthocranion, nasion, external auditory meatus, C4, T1, and pelvis). Angular velocity of the head, seat belt forces, and reaction forces on the seat pan and foot rest were also measured. The ATD exhibited significantly greater shoulder and lap belt, foot rest, and seat pan normal reaction loads compared to the PVs. Contrarily, PVs exhibited significantly greater seat pan shear. The ATD experienced significantly greater head angular velocity (11.4 ± 1.7 rad/s vs. 8.1 ± 1.4 rad/s), resulting in a quicker time to maximum head rotation (280.4 ± 2.5 ms vs 334.2 ± 21.7 ms). The ATD exhibited significantly less forward excursions of the nasion (171.7 ± 7.8 mm vs. 199.5 ± 12.3 mm), external auditory meatus (194.5 ± 11.8 mm vs. 205.7 ± 10.3 mm), C4 (127.0 ± 5.2 mm vs. 183.3 ± 12.8 mm) and T1 (111.1 ± 6.5 mm vs. 153.8 ± 10.5 mm) compared to the PVs. These analyses provide insight into aspects of ATD biofidelity in low-speed crash environments.
The Bruton's Tyrosine Kinase (BTK) Inhibitor, Ibrutinib (PCI-32765), Has Preferential Activity in the ABC Subtype of Relapsed/Refractory De Novo Diffuse Large B-Cell Lymphoma (DLBCL): Interim Results of a Multicenter, Open-Label, Phase 2 Study
Ash Annual Meeting Abstracts, Nov 16, 2012
Comparison of Kinematic Responses of the Head and Spine for Children and Adults in Low-Speed Frontal Sled Tests
Stapp Car Crash Journal, Nov 1, 2009
Previous research has suggested that the pediatric ATD spine, developed from scaling the adult AT... more Previous research has suggested that the pediatric ATD spine, developed from scaling the adult ATD spine, may not adequately represent a child's spine and thus may lead to important differences in the ATD head trajectory relative to a human. To gain further insight into this issue, the objectives of this study were, through non-injurious frontal sled tests on human volunteers, to 1) quantify the kinematic responses of the restrained child's head and spine and 2) compare pediatric kinematic responses to those of the adult. Low-speed frontal sled tests were conducted using male human volunteers (20 subjects: 6-14 years old, 10 subjects: 18-40 years old), in which the safety envelope was defined from an amusement park bumper-car impact. Each subject was restrained by a custom-fit lap and shoulder belt system and photo-reflective targets were attached to a tight-fitting cap worn on the head or adhered to the skin overlying skeletal landmarks on the head, spine, shoulders, sternum, and legs. A 3-D near-infrared target tracking system quantified the position of the following markers: head top, external auditory meatus, nasion, opisthocranion, C4, T1, T4, and T8. Trajectory data were normalized by subject seated height and head and spine rotations were calculated. The Generalized Estimating Equations method was used to determine the effect of age and key anthropometric measures on marker excursion. For all markers, the normalized forward excursion significantly decreased with age and all spinal markers moved upward due to a combination of rigid body rotation and spinal flexion with lesser upward movement with age. The majority of the spine flexion occurred at the base of the neck not in the upper cervical spine and the magnitude of flexion was greatest for the youngest subjects. Additional flexion occurred in the thoracic spine as well. Our findings indicate that the primary factor governing the differences in normalized head and spinal trajectories between the various age groups was decreasing head-to-neck girth ratio with increasing age. Other factors, such as muscle response and cervical vertebral structural properties, may also contribute to the differences, but were not evaluated in this paper. These results can serve as a data set for validating the responses of restrained ATDs and computational human models to low severity frontal collisions.
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Papers by Sriram Balasubramanian