<p>Today, micro- and nano-electronic devices are becoming more complex and advanced as the dimensions are shrinking. It is therefore a very challenging task to develop new device technologies with performance that can be predicted. This thesis focuses on advanced measurement techniques and TCAD simulations in order to characterize and understand the device physics of advanced semiconductor devices. </p><p>TCAD simulations were made on a novel MOSFET device with asymmetric source and drain structures. The results showed that there exists an optimum range of implantation doses where the device has a significantly higher figure-of-merit regarding speed and voltage capability, compared to a symmetric MOSFET. Furthermore, both 2D and 3D simulations were used to develop a resistive model of the substrate noise coupling. </p><p>Of particular interest to this thesis is the random dopant fluctuation (RDF). The result of RDF can be characterized using very advance and reliable measurement techniques. In the thesis an ultra-high precision parametric mismatch measurement system was designed and implemented. The best ever reported performance on short-term repeatability of the measurements was demonstrated. A new bipolar parametric mismatch phenomenon was also revealed using the measurement system.</p><p>A complete simulation platform, called SiSPET (Simulated Statistical Parameter Extraction Tool), was developed and integrated into the framework of a commercial TCAD environment. A special program for randomization of the doping was developed and proven to provide RDF effects in agreement measurement. The SiSPET system was used to investigate how different device models were able to take RDF effects into account. The RDF effects were translated in to parameter fluctuations using the developed extraction routines. It was shown that the basic MOSFET fluctuation model could be improved by including the field dependenent mobility. However, if a precise description of the fluctuations is required an advanced compact-model, such as MOS Model 11 should be used.</p>

Today, micro- and nano-electronic devices are becoming more complex and advanced as the dimensions are shrinking. It is therefore a very challenging task to develop new device technologies with performance that can be predicted. This thesis focuses on advanced measurement techniques and TCAD simulations in order to characterize and understand the device physics of advanced semiconductor devices. TCAD simulations were made on a novel MOSFET device with asymmetric source and drain structures. The results showed that there exists an optimum range of implantation doses where the device has a significantly higher figure-of-merit regarding speed and voltage capability, compared to a symmetric MOSFET. Furthermore, both 2D and 3D simulations were used to develop a resistive model of the substrate noise coupling. Of particular interest to this thesis is the random dopant fluctuation (RDF). The result of RDF can be characterized using very advance and reliable measurement techniques. In the thesis an ultra-high precision parametric mismatch measurement system was designed and implemented. The best ever reported performance on short-term repeatability of the measurements was demonstrated. A new bipolar parametric mismatch phenomenon was also revealed using the measurement system. A complete simulation platform, called SiSPET (Simulated Statistical Parameter Extraction Tool), was developed and integrated into the framework of a commercial TCAD environment. A special program for randomization of the doping was developed and proven to provide RDF effects in agreement measurement. The SiSPET system was used to investigate how different device models were able to take RDF effects into account. The RDF effects were translated in to parameter fluctuations using the developed extraction routines. It was shown that the basic MOSFET fluctuation model could be improved by including the field dependenent mobility. However, if a precise description of the fluctuations is required an advanced compact-model, such as MOS Model 11 should be used.

Σκοπός της παρούσας διδακτορικής διατριβής είναι η μελέτη της επίδρασης των τεχνολογικών διεργασιών στην κινητική των προσμίξεων σε ημιαγωγούς της ομάδας IV καθώς και η διερεύνηση των φυσικών μηχανισμών που επηρεάζουν την κινητική των σημειακών ατελειών και κατ’ επέκταση τη διάχυση και ενεργοποίηση των προσμίξεων. Αρχικά μελετήθηκε η επίδραση της θερμικής ανόπτησης στην απώλεια δόσης των πρόσμιξεων στο γερμάνιο, η οποία είναι πολύ σημαντική για την κατασκευή διατάξεων. Από τα πειραματικά αποτελέσματα τόσο σε νοθευμένα όσο και σε μη-νοθευμένα υποστρώματα γερμανίου διαπιστώθηκε ότι, σε αντίθεση με ότι αναφέρεται στη βιβλιογραφία, η απώλεια δόσης της πρόσμιξης είναι αποτέλεσμα της απώλειας του υποστρώματος και όχι της εξω-διάχυσης της πρόσμιξης. Επιπλέον βρέθηκε ότι ο ρυθμός απώλειας συνδέεται με την συγκέντρωση των πλεγματικών κενών στο υπόστρωμα, γεγονός που υποδυκνύει ότι η απώλεια του υποστρώματος οφείλεται σε εξάχνωση του γερμανίου. Στην συνέχεια μελετήθηκε η κινητική των δύο βασικών προσμίξεων p-τύπου στο γερμάνιο, του Γαλλίου και του Βορίου, μετά από ιοντική εμφύτευση και ανόπτηση. Για την περίπτωση του Γαλλίου μελετήθηκε η διάχυση και ενεργοποίηση τόσο σε χαμηλές όσες και υψηλές συγκεντρώσεις. Διαπιστώθηκε ότι σε χαμηλές συγκεντρώσεις το Γάλλιο διαχέεται πολύ αργά σε συμφωνία με προηγούμενα πειραματικά αποτελέσματα, αν και παρατηρήθηκε μία αυξημένη τάση για εξω- διάχυση σε θερμοκρασίες μεγαλύτερες από 650oC. Σε υψηλές συγκεντρώσεις, διαπιστώθηκε ότι το γάλλιο είναι σχεδόν ακίνητο γύρω από το μέγιστο της κατανομής του, ενδεικτικό της δημιουργίας συσσωματωμάτων και εμφανίζει αυξημένη διάχυση στην ουρά της κατανομής. Για την περίπτωση του Βορίου μελετήθηκε η κινητική της διάχυσης μετά από συν-εμφύτευση Βορίου και Φωσφόρου. Διαπιστώθηκε ότι η διάχυση του Βορίου δεν επηρεάζεται από την παρουσία του Φωσφόρου ακόμα και σε πολύ υψηλές συγκεντρώσεις. Σε αντίθεση η παρουσία του Βορίου σε υψηλές συγκεντρώσεις μπορεί να επιβραδύνει ή και να σταματήσει τη διάχυση του Φωσφόρου, ενδεικτικό ότι ο Φώσφορος κινείται κυρίως με διπλά φορτισμένα πλεγματικά κενά. Τέλος μελετήθηκε η επίδραση της οξεινιτριδίωσης στην διάχυση του γερμανίου από υποστρώματα SiGe σε υπερκείμενο υμένιο πυριτίου υπό μηχανική τάση και η επίδραση της στα ηλεκτρικά χαρακτηριστικά των διατάξεων MOS / -

The tri-gate FET has been hailed as the biggest breakthrough in transistor technology in the last 20 years. The increase in device performance (faster switching, less delay, improved short channel effects, etc.) coupled with the reduction in device size, would allow for huge gains in the electronics industry. This thesis aims to not only investigate the validity of these claims, but also how random dopant fluctuation (RDF) affects the tri-gates performance and how to curb these issues. In order to achieve this, an atomistic 3-D device simulation program was utilized in order to capture the many quantum mechanical effects that devices of this size experience and compare the results against a similar planar device. We see the tri-gate FET does indeed perform extremely well compared to its planar counterpart, but both devices experience a great deal of fluctuations due to the random dopants in the device. In order to limit the RDF effects a variety of methods were implemented including increasing doping concentrations in the channel, source, and drain regions, varying the source/drain junction depths, and varying the source/drain contact workfunction. The results showed that increasing doping concentrations in order to reduce the amount of space the dopants had to diffuse did not reduce the randomness experienced by the devices, but rather the randomness increased. The dopant fluctuation was insensitive to the varying of the workfunction, but was found to decrease with an increase in junction depth in the source/drain regions. With randomness in the tri-gate reduced, the overall performance should increase when used in ICs, where consistency in device characteristics is essential.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第14574号 / 工博第3042号 / 新制||工||1453(附属図書館) / 26926 / UT51-2009-D286 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 粟倉 泰弘, 教授 杉村 博之, 教授 田中 功 / 学位規則第4条第1項該当

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15377号 / 工博第3256号 / 新制||工||1490(附属図書館) / 27855 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 松原 英一郎, 教授 田中 功, 准教授 宇田 哲也 / 学位規則第4条第1項該当

Reverse engineering of hardware IP block is a common practice for competitive purposes in the semiconductor industry. What is done with the information gathered is the deciding legal factor. Once this information gets into the hands of an attacker, it can be used to manufacture exact clones of the hardware device. In an attempt to prevent the illegal copies of the IP block from flooding the market, layout-level obfuscation based on switchable dopant is suggested for the hardware design. This approach can be integrated into the design and manufacturing flow using an obfuscation tool (ObfusTool) to obfuscate the functionality of the IP core. The ObfusTool is developed in a way to be flexible and adapt to different standard cell libraries and designs. It enables easy and accurate evaluation of the area, power and delay v/s obfuscation trades-offs across different design approaches for hardware obfuscation. The ObfusTool is linked to an obfuscation standard cell library which is based on a prototype design created with Obfuscells and 4-input NAND gate. The Obfuscell is a standard cell which is created with switchable functionality based on the assigned dopant configurations. The Obfuscell is combined with other logic gates to form a standard cell library, which can replace any number of existing gates in the IP block without altering it's functionality. A total of 160 different gates are realized using permutated combinations starting with 26 unique gate functions. This design library provide a high level of obfuscation in terms of the number of combinations an adversary has to go through increase to 2 2000 approximately based on the design under consideration. The connectivity of the design has been ignored by previous approaches, which we have addressed in this thesis. The connectivity of a design leaks important information related to inputs and outputs of a gate. We extend the basic idea of dopant-based hardware obfuscation by introducing "dummy wires". The addition of dummy wires not only obfuscates the functionality of the design but also it's connectivity. This greatly reduces the information leakage and complexity of the design increases. To an attacker the whole design appears as one big 'blob'.This also curbs the attempts of brute force attacks. The introduced obfuscation comes at a cost of area and power overhead on an average 5x, which varies across different design libraries.

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No description available.

Many applications of metal-organic frameworks (MOFs) are highly dependent on their structures. The type and consistency of structure inform their properties. Zinc-based MOFs are applicable in different fields because of the low toxicity of zinc materials and are therefore also useful for catalysis. While MOF-5, a zinc-based MOF with carboxylate linkers is moisture intolerant, a variant of this is moisture tolerant. The introduction of a nitrogen-based linker in the zinc MOF which renders the structure moisture-tolerant. This material has not been explored as much, despite its multifunctional properties. Furthermore, the growth of Zn-based bimetallics of this MOF has not yet been explored. In this work, I studied the synthesis of this zinc-based moisture-tolerant MOF-5 as a thin film using a simple, fast, and cost-effective layer-by-layer wet synthesis method on different substrate surfaces. I successfully synthesized a series of bimetallics of this MOF as thin films on an untreated silicon wafer substrate. The successful synthesis of these materials was confirmed using X-ray photoelectron spectroscopy, X-ray diffraction, and Raman spectroscopy techniques. Additionally, some software data analysis tools were used for the characterization of the surface of the thin films to quantify the chemical composition. Future applications of these materials will be as sorbent materials for the capture of CO2 and its subsequent conversion to CO which is a synthesis gas for different useful materials like fuel and other chemical materials.