A novel high-k gate dielectric material, i.e., hafnium-doped tantalum oxide (Hf-doped TaOx), has been studied for the application of the future generation metal-oxidesemiconductor field effect transistor (MOSFET). The film's electrical, chemical, and structural properties were investigated experimentally. The incorporation of Hf into TaOx impacted the electrical properties. The doping process improved the effective dielectric constant, reduced the fixed charge density, and increased the dielectric strength. The leakage current density also decreased with the Hf doping concentration. MOS capacitors with sub-2.0 nm equivalent oxide thickness (EOT) have been achieved with the lightly Hf-doped TaOx. The low leakage currents and high dielectric constants of the doped films were explained by their compositions and bond structures. The Hf-doped TaOx film is a potential high-k gate dielectric for future MOS transistors. A 5 àtantalum nitride (TaNx) interface layer has been inserted between the Hf-doped TaOx films and the Si substrate to engineer the high-k/Si interface layer formation and properties. The electrical characterization result shows that the insertion of a 5 àTaNx between the doped TaOx films and the Si substrate decreased the film's leakage current density and improved the effective dielectric constant (keffective) value. The improvement of these dielectric properties can be attributed to the formation of the TaOxNy interfacial layer after high temperature O2 annealing. The main drawback of the TaNx interface layer is the high interface density of states and hysteresis, which needs to be decreased. Advanced metal nitride gate electrodes, e.g., tantalum nitride, molybdenum nitride, and tungsten nitride, were investigated as the gate electrodes for atomic layer deposition (ALD) HfO2 high-k dielectric material. Their physical and electrical properties were affected by the post metallization annealing (PMA) treatment conditions. Work functions of these three gate electrodes are suitable for NMOS applications after 800°C PMA. Metal nitrides can be used as the gate electrode materials for the HfO2 high-k film. The novel high-k gate stack structures studied in this study are promising candidates to replace the traditional poly-Si-SiO2 gate stack structure for the future CMOS technology node.

As is predicted by Moore’s law, the transistors in microprocessors increase dramatically. In order to increase the power density of the microprocessors, the switching frequency of the Voltage Regulator (VR) is expected to increase to MHz level. However, the frequency dependent loss will increase proportionally. In order to meet requirements of the next-generation microprocessors, three new ideas are proposed in this thesis. The first contribution is a new bipolar Current Source Driver (CSD) for high frequency power MOSFET. The proposed CSD alleviates the gate current diversion problem of the existing CSDs by clamping the gate voltage to a flexible negative value during turn off transition. Therefore, the proposed driver turns off the MOSFET much faster. For buck converters with 12 V input at 1MHz switching frequency, the proposed driver improves the efficiency from 80.5% using the existing CSD to 82.5% at 1.2V/30A, and at 1.3V/30A output, from 82.5% to 83.9%. The second contribution is an accurate analytical loss model of a power MOSFET with a CSD. The current diversion problem that commonly exists in CSDs is investigated mathematically. The inductor value of the CSD is optimized to achieve minimum loss for the synchronous buck converter. The experimentally measured loss matches the calculated loss very well. The efficiency with the optimal CSD inductor is improved from 86.1% to 87.6% at 12V input, 1.3V/20A output in 1MHz switching frequency and from 82.4% to 84.0% at 1.3V/30A output. The third contribution is a new inductorless bipolar gate driver for control FET of buck converters. The most important advantage of the driver presented in this thesis is that it can turn off the power MOSFETs with a negative voltage, which will significantly reduce the turn off time and thus switching loss. In addition, the proposed bipolar gate driver has no inductor in the driver circuit; therefore it can be fully integrated into a chip. For buck converter with 5V input, 1.3V/25A load, in 2 MHz frequency, the proposed gate driver increases the efficiency from 75.8% to 77.8% and from 72.9% to 76.5% at 5V input, 1.3V/25A load, in 2.5 MHz switching frequency. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2010-07-30 14:06:04.003

Zugl.: Hamburg, Techn. Univ., Diss., 2008

Esta Tese apresenta os resultados da simulação do transporte eletrônico em três dimensões (3D) no nano dispositivo eletrônico conhecido como “SOI-FinFET”. Este dispositivo é um transistor MOS em tecnologia Silício sobre Isolante – “Silicon-on- Insulator”, SOI – com porta dupla e cujo canal e zonas de fonte e dreno são realizadas em uma estrutura nanométrica vertical de silício chamada de “finger” ou “fin”. Como introdução ao dispositivo em questão, é feita uma revisão básica sobre a tecnologia e transistores SOI e sobre MOSFETs de múltiplas portas. A implementação de um modelo tipo “charge-sheet” para o transistor SOI-MOSFET totalmente depletado e uma modelagem deste dispositivo em altas frequências também é apresentada. A geometria do “fin” é escalada para valores menores do que 100 nm, com uma espessura entre 10 e 20 nm. Um dos objetivos deste trabalho é a definição de parâmetros para o SOI-FinFET que o viabilizem para a tecnologia de 22 nm, com um comprimento efetivo de canal menor do que 20 nm. O transistor FinFET e uma estrutura básica simplificada para simulação numérica em 3D são descritos, sendo utilizados dados de tecnologias atuais de fabricação. São apresentados resultados de simulação numérica 3D (curvas ID-VG, ID-VD, etc.) evidenciando as principais características de funcionamento do FinFET. É analisada a influência da espessura e dopagem do “fin” e do comprimento físico do canal em parâmetros importantes como a tensão de limiar e a inclinação de sublimiar. São consideradas e analisadas duas possibilidades de dopagens da área ativa do “fin”: (1) o caso em que esta pode ser considerada não dopada, sendo baixíssima a probabilidade da presença de dopantes ativos, e (2) o caso de um alto número de dopantes ativos (> 10 é provável). Uma comparação entre dois simuladores numéricos 3D de dispositivos é realizada no intuito de explicitar diferenças entre modelos de simulação e características de descrição de estruturas 3D. São apresentadas e analisadas medidas em dispositivos FinFET experimentais. Dois métodos de extração de resistência série parasita são utilizados em FinFETs simulados e caracterizados experimentalmente. Para finalizar, são resumidas as principais conclusões deste trabalho e são propostos os trabalhos futuros e novas diretivas na pesquisa dos transistores FinFETs. / This thesis presents the results of 3D-numerical simulation of electron transport in double-gate SOI-FinFETs in the decanometer size range. A basic review on the SOI technology and multiple gates MOSFETs is presented. The implementation of a chargesheet model for the fully-depleted SOI-MOSFET and a high frequency modeling of this device are first presented for a planar device topology. The second part of this work deals with FinFETs, a non-planar topology. The geometry of the silicon nano-wire (or “fin”) in this thesis is scaled down well below 100 nm, with fin thickness in the range of 10 to 20 nm. This work addresses the parameters for a viable 22 nm CMOS node, with electrical effective channel lengths below 20 nm. The basic 3D structure of the FinFET transistor is described in detail, then it is simulated with various device structural parameters, and results of 3D-numerical simulation (ID-VG curves, ID-VD, etc.), showing the main features of operation of this device, are presented. The impacts of varying silicon fin thicknesses, physical channel lengths, and silicon fin doping concentration on both the average threshold voltage and the subthreshold slope are investigated. With respect to the doping concentration, the discrete and highly statistical nature of impurity presence in the active area of the nanometer-range fin is considered in two limiting cases: (1) the zero-doping or undoped case, for highly improbable presence of active dopants, and (2) the many-dopants case, or high number (> 10 are probable) of active dopants in the device channel. A comparison between two 3D-numerical device simulators is performed in order to clarify differences between simulation models and features of the description of 3D structures. A structure for SOIFinFETs is optimized, for the undoped fin, showing its applicability for devices with electrical effective channel lengths below 20 nm. SOI-FinFET measurements were performed on experimental devices, analyzed and compared to device simulation results. This thesis uses parasitic resistance extraction methods that are tested in FinFET simulations and measurements. Finally, the main conclusions of this work are summarized and the future work and new directions in the FinFETs research are proposed.

Du fait de l'augmentation de la demande de produits pour les applications grand public, industrielles et automobiles, des mémoires embarquées fiables et à faible coût de fabrication sont de plus en plus demandées. Dans ce contexte, les mémoires split-gate à piégeage discret sont proposées pour des microcontrôleurs. Elles combinent l'avantage d'une couche de stockage discrète et de la con guration split-gate. Durant ce travail de recherche, des mémoires split-gate à couche de piégeage discret ayant des longueurs de grille de 20nm sont présentées pour la première fois. Celles-ci on été réalisées avec des nanocristaux de silicium (Si-nc), du nitrure de silicium (SiN) ou un hybride Si-nc/SiN avec diélectrique de control de type SiO2 ou AlO et sont comparées en termes de performances lors des procédures d'eff acement et de rétention. Ensuite, la miniaturisation des mémoires split-gate à piégeage de charge est étudié, en particulier au travers de l'impact de la réduction de la longueur de grille sur la fenêtre de mémorisation, la rétention et la consommation. Le rôle des défauts dans le diélectrique de contrôle (alumine) utilisé dans les mémoires de type TANOS a été étudié. Des travaux ont été menés pour déterminer l'origine des pièges dans ce matériau, par le biais de la simulation atomistique ainsi que d'analyses physico-chimiques précises. Nous avons montré que la concentration de pièges dans AlO pouvait être réduite par ajustement des conditions de procédé de fabrication, débouchant ainsi sur l'amélioration de la rétention dans les mémoires à piégeage de charge. Ce résultat est convenable pour les applications de type embarqué / Due to the increasing demand for consumer, industrial and automotive products, highly reliable, and low integration cost embedded memories are more and more required. In this context, split-gate charge trap memories were proposed for microcontroller products, combining the advantage of a discrete storage layer and of the split-gate con guration. In this thesis, split-gate charge trap memories with electrical gate length down to 20nm are presented for the 1st time. Silicon nanocristals (Si-nc), or silicon nitride (SiN) and hybrid Si-nc/SiN based split-gate memories, with SiO2 or AlO control dielectrics, are compared in terms of program erase and retention. Then, the scalability of split-gate charge trap memories is studied, investigating the impact of gate length reduction on the memory window, retention and consumption. We thus studied the role of defects on alumina control dielectric employed in TANOS-like memory. We used atomistic simulation, consolidated by a detailed alumina physico-chemical material analysis, to investigate the origin of traps in alumina. We showed that the trap concentration in AlO can be decreased by adjusting the process conditions leading to improved retention behaviour in charge trap memory, suitable for embedded applications.

Esta Tese apresenta os resultados da simulação do transporte eletrônico em três dimensões (3D) no nano dispositivo eletrônico conhecido como “SOI-FinFET”. Este dispositivo é um transistor MOS em tecnologia Silício sobre Isolante – “Silicon-on- Insulator”, SOI – com porta dupla e cujo canal e zonas de fonte e dreno são realizadas em uma estrutura nanométrica vertical de silício chamada de “finger” ou “fin”. Como introdução ao dispositivo em questão, é feita uma revisão básica sobre a tecnologia e transistores SOI e sobre MOSFETs de múltiplas portas. A implementação de um modelo tipo “charge-sheet” para o transistor SOI-MOSFET totalmente depletado e uma modelagem deste dispositivo em altas frequências também é apresentada. A geometria do “fin” é escalada para valores menores do que 100 nm, com uma espessura entre 10 e 20 nm. Um dos objetivos deste trabalho é a definição de parâmetros para o SOI-FinFET que o viabilizem para a tecnologia de 22 nm, com um comprimento efetivo de canal menor do que 20 nm. O transistor FinFET e uma estrutura básica simplificada para simulação numérica em 3D são descritos, sendo utilizados dados de tecnologias atuais de fabricação. São apresentados resultados de simulação numérica 3D (curvas ID-VG, ID-VD, etc.) evidenciando as principais características de funcionamento do FinFET. É analisada a influência da espessura e dopagem do “fin” e do comprimento físico do canal em parâmetros importantes como a tensão de limiar e a inclinação de sublimiar. São consideradas e analisadas duas possibilidades de dopagens da área ativa do “fin”: (1) o caso em que esta pode ser considerada não dopada, sendo baixíssima a probabilidade da presença de dopantes ativos, e (2) o caso de um alto número de dopantes ativos (> 10 é provável). Uma comparação entre dois simuladores numéricos 3D de dispositivos é realizada no intuito de explicitar diferenças entre modelos de simulação e características de descrição de estruturas 3D. São apresentadas e analisadas medidas em dispositivos FinFET experimentais. Dois métodos de extração de resistência série parasita são utilizados em FinFETs simulados e caracterizados experimentalmente. Para finalizar, são resumidas as principais conclusões deste trabalho e são propostos os trabalhos futuros e novas diretivas na pesquisa dos transistores FinFETs. / This thesis presents the results of 3D-numerical simulation of electron transport in double-gate SOI-FinFETs in the decanometer size range. A basic review on the SOI technology and multiple gates MOSFETs is presented. The implementation of a chargesheet model for the fully-depleted SOI-MOSFET and a high frequency modeling of this device are first presented for a planar device topology. The second part of this work deals with FinFETs, a non-planar topology. The geometry of the silicon nano-wire (or “fin”) in this thesis is scaled down well below 100 nm, with fin thickness in the range of 10 to 20 nm. This work addresses the parameters for a viable 22 nm CMOS node, with electrical effective channel lengths below 20 nm. The basic 3D structure of the FinFET transistor is described in detail, then it is simulated with various device structural parameters, and results of 3D-numerical simulation (ID-VG curves, ID-VD, etc.), showing the main features of operation of this device, are presented. The impacts of varying silicon fin thicknesses, physical channel lengths, and silicon fin doping concentration on both the average threshold voltage and the subthreshold slope are investigated. With respect to the doping concentration, the discrete and highly statistical nature of impurity presence in the active area of the nanometer-range fin is considered in two limiting cases: (1) the zero-doping or undoped case, for highly improbable presence of active dopants, and (2) the many-dopants case, or high number (> 10 are probable) of active dopants in the device channel. A comparison between two 3D-numerical device simulators is performed in order to clarify differences between simulation models and features of the description of 3D structures. A structure for SOIFinFETs is optimized, for the undoped fin, showing its applicability for devices with electrical effective channel lengths below 20 nm. SOI-FinFET measurements were performed on experimental devices, analyzed and compared to device simulation results. This thesis uses parasitic resistance extraction methods that are tested in FinFET simulations and measurements. Finally, the main conclusions of this work are summarized and the future work and new directions in the FinFETs research are proposed.

Esta Tese apresenta os resultados da simulação do transporte eletrônico em três dimensões (3D) no nano dispositivo eletrônico conhecido como “SOI-FinFET”. Este dispositivo é um transistor MOS em tecnologia Silício sobre Isolante – “Silicon-on- Insulator”, SOI – com porta dupla e cujo canal e zonas de fonte e dreno são realizadas em uma estrutura nanométrica vertical de silício chamada de “finger” ou “fin”. Como introdução ao dispositivo em questão, é feita uma revisão básica sobre a tecnologia e transistores SOI e sobre MOSFETs de múltiplas portas. A implementação de um modelo tipo “charge-sheet” para o transistor SOI-MOSFET totalmente depletado e uma modelagem deste dispositivo em altas frequências também é apresentada. A geometria do “fin” é escalada para valores menores do que 100 nm, com uma espessura entre 10 e 20 nm. Um dos objetivos deste trabalho é a definição de parâmetros para o SOI-FinFET que o viabilizem para a tecnologia de 22 nm, com um comprimento efetivo de canal menor do que 20 nm. O transistor FinFET e uma estrutura básica simplificada para simulação numérica em 3D são descritos, sendo utilizados dados de tecnologias atuais de fabricação. São apresentados resultados de simulação numérica 3D (curvas ID-VG, ID-VD, etc.) evidenciando as principais características de funcionamento do FinFET. É analisada a influência da espessura e dopagem do “fin” e do comprimento físico do canal em parâmetros importantes como a tensão de limiar e a inclinação de sublimiar. São consideradas e analisadas duas possibilidades de dopagens da área ativa do “fin”: (1) o caso em que esta pode ser considerada não dopada, sendo baixíssima a probabilidade da presença de dopantes ativos, e (2) o caso de um alto número de dopantes ativos (> 10 é provável). Uma comparação entre dois simuladores numéricos 3D de dispositivos é realizada no intuito de explicitar diferenças entre modelos de simulação e características de descrição de estruturas 3D. São apresentadas e analisadas medidas em dispositivos FinFET experimentais. Dois métodos de extração de resistência série parasita são utilizados em FinFETs simulados e caracterizados experimentalmente. Para finalizar, são resumidas as principais conclusões deste trabalho e são propostos os trabalhos futuros e novas diretivas na pesquisa dos transistores FinFETs. / This thesis presents the results of 3D-numerical simulation of electron transport in double-gate SOI-FinFETs in the decanometer size range. A basic review on the SOI technology and multiple gates MOSFETs is presented. The implementation of a chargesheet model for the fully-depleted SOI-MOSFET and a high frequency modeling of this device are first presented for a planar device topology. The second part of this work deals with FinFETs, a non-planar topology. The geometry of the silicon nano-wire (or “fin”) in this thesis is scaled down well below 100 nm, with fin thickness in the range of 10 to 20 nm. This work addresses the parameters for a viable 22 nm CMOS node, with electrical effective channel lengths below 20 nm. The basic 3D structure of the FinFET transistor is described in detail, then it is simulated with various device structural parameters, and results of 3D-numerical simulation (ID-VG curves, ID-VD, etc.), showing the main features of operation of this device, are presented. The impacts of varying silicon fin thicknesses, physical channel lengths, and silicon fin doping concentration on both the average threshold voltage and the subthreshold slope are investigated. With respect to the doping concentration, the discrete and highly statistical nature of impurity presence in the active area of the nanometer-range fin is considered in two limiting cases: (1) the zero-doping or undoped case, for highly improbable presence of active dopants, and (2) the many-dopants case, or high number (> 10 are probable) of active dopants in the device channel. A comparison between two 3D-numerical device simulators is performed in order to clarify differences between simulation models and features of the description of 3D structures. A structure for SOIFinFETs is optimized, for the undoped fin, showing its applicability for devices with electrical effective channel lengths below 20 nm. SOI-FinFET measurements were performed on experimental devices, analyzed and compared to device simulation results. This thesis uses parasitic resistance extraction methods that are tested in FinFET simulations and measurements. Finally, the main conclusions of this work are summarized and the future work and new directions in the FinFETs research are proposed.

This paper presents the design of a reconfigurable asynchronous unit, called the pulsed quad-cell (PQ-cell), for conformal computing. The conformal computing vision is to create computational materials that can conform to the physical and computational needs of an application. PQ-cells, like cellular automata, are assembled into arrays with nearest neighbor communication and are capable of general computation. They operate asynchronously to minimize power consumption and to allow sealing without the limitations imposed by a global clock. Cell operations are stimulated by pulses which use two wires to encode a data bit. Cells are individually reconfirgurable to perform logic, move and store information, and coordinate parallel activity. The PQ-cell design targets a 0.25 μm CMOS technology. Simulation results show that a PQ-cell, when pulsed at 1.3 GHz, consumes 16.9 pJ per operation. Examples of self-timed multi-cell structures include a 98 MHz ring oscillator and a 385 MHz pipeline.

No description available.

No description available.