Materials for high-density electronic packaging and interconnection

Electronic packaging and interconnections are the elements that today limit the ultimate performance of advanced electronic systems. Materials in use today and those becoming available are critically examined to ascertain what actions are needed for U.S. industry to compete favorably in the world market for advanced electronics. Materials and processes are discussed in terms of the final properties achievable and systems design compatibility. Weak points in the domestic industrial capability, including technical, industrial philosophy, and political, are identified. Recommendations are presented for actions that could help U.S. industry regain its former leadership position in advanced semiconductor systems production

Limitations and opportunities for wire length prediction in gigascale integration

Wires have become a major source of bottleneck in current VLSI designs, and wire length prediction is therefore essential to overcome these bottlenecks. Wire length prediction is broadly classified into two types: macroscopic prediction, which is the prediction of wire length distribution, and microscopic prediction, which is the prediction of individual wire lengths. The objective of this thesis is to develop a clear understanding of limitations to both macroscopic and microscopic a priori, post-placement, pre-routing wire length predictions, and thereby develop better wire length prediction models. Investigations carried out to understand the limitations to macroscopic prediction reveal that, in a given design (i) the variability of the wire length distribution increases with length and (ii) the use of Rent s rule with a constant Rent s exponent p, to calculate the terminal count of a given block size, limits the accuracy of the results from a macroscopic model. Therefore, a new model for the parameter p is developed to more accurately reflect the terminal count of a given block size in placement, and using this, a new more accurate macroscopic model is developed. In addition, a model to predict the variability is also incorporated into the macroscopic model. Studies to understand limitations to microscopic prediction reveal that (i) only a fraction of the wires in a given design are predictable, and these are mostly from shorter nets with smaller degrees and (ii) the current microscopic prediction models are built based on the assumption that a single metric could be used to accurately predict the individual length of all the wires in a design. In this thesis, an alternative microscopic model is developed for the predicting the shorter wires based on a hypothesis that there are multiple metrics that influence the length of the wires. Three different metrics are developed and fitted into a heuristic classification tree framework to provide a unified and more accurate microscopic model.Ph.D.Committee Chair: Dr. Jeff Davis; Committee Member: Dr. James D. Meindl; Committee Member: Dr. Paul Kohl; Committee Member: Dr. Scott Wills; Committee Member: Dr. Sung Kyu Li

Design automation and analysis of three-dimensional integrated circuits

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 165-176).This dissertation concerns the design of circuits and systems for an emerging technology known as three-dimensional integration. By stacking individual components, dice, or whole wafers using a high-density electromechanical interconnect, three-dimensional integration can achieve scalability and performance exceeding that of conventional fabrication technologies. There are two main contributions of this thesis. The first is a computer-aided design flow for the digital components of a three-dimensional integrated circuit (3-D IC). This flow primarily consists of two software tools: PR3D, a placement and routing tool for custom 3-D ICs based on standard cells, and 3-D Magic, a tool for designing, editing, and testing physical layout characteristics of 3-D ICs. The second contribution of this thesis is a performance analysis of the digital components of 3-D ICs. We use the above tools to determine the extent to which 3-D integration can improve timing, energy, and thermal performance. In doing so, we verify the estimates of stochastic computational models for 3-D IC interconnects and find that the models predict the optimal 3-D wire length to within 20% accuracy. We expand upon this analysis by examining how 3-D technology factors affect the optimal wire length that can be obtained. Our ultimate analysis extends this work by directly considering timing and energy in 3-D ICs. In all cases we find that significant performance improvements are possible. In contrast, thermal performance is expected to worsen with the use of 3-D integration. We examine precisely how thermal behavior scales in 3-D integration and determine quantitatively how the temperature may be controlled during the circuit placement process. We also show how advanced packaging(cont.) technologies may be leveraged to maintain acceptable die temperatures in 3-D ICs. Finally, we explore two issues for the future of 3-D integration. We determine how technology scaling impacts the effect of 3-D integration on circuit performance. We also consider how to improve the performance of digital components in a mixed-signal 3-D integrated circuit. We conclude with a look towards future 3-D IC design tools.by Shamik Das.Ph.D

Routing congestion analysis and reduction in deep sub-micron VLSI design

Congestion is one of the main optimization objectives in global routing. However, the optimization performance is constrained because the cells are already fixed at this stage. Therefore, designer can save substantial time and resources by detecting and reducing congested regions during the planning stages. An efficient and yet accurate congestion estimation model is crucial to be included in the inner loop of floorplanning and placement design. In this dissertation, we mainly focus on routing congestion modeling and reduction during floorplanning and placement

Predicting power scalability in a reconfigurable platform

This thesis focuses on the evolution of digital hardware systems. A reconfigurable platform is proposed and analysed based on thin-body, fully-depleted silicon-on-insulator Schottky-barrier transistors with metal gates and silicide source/drain (TBFDSBSOI). These offer the potential for simplified processing that will allow them to reach ultimate nanoscale gate dimensions. Technology CAD was used to show that the threshold voltage in TBFDSBSOI devices will be controllable by gate potentials that scale down with the channel dimensions while remaining within appropriate gate reliability limits. SPICE simulations determined that the magnitude of the threshold shift predicted by TCAD software would be sufficient to control the logic configuration of a simple, regular array of these TBFDSBSOI transistors as well as to constrain its overall subthreshold power growth. Using these devices, a reconfigurable platform is proposed based on a regular 6-input, 6-output NOR LUT block in which the logic and configuration functions of the array are mapped onto separate gates of the double-gate device. A new analytic model of the relationship between power (P), area (A) and performance (T) has been developed based on a simple VLSI complexity metric of the form ATσ = constant. As σ defines the performance “return” gained as a result of an increase in area, it also represents a bound on the architectural options available in power-scalable digital systems. This analytic model was used to determine that simple computing functions mapped to the reconfigurable platform will exhibit continuous power-area-performance scaling behavior. A number of simple arithmetic circuits were mapped to the array and their delay and subthreshold leakage analysed over a representative range of supply and threshold voltages, thus determining a worse-case range for the device/circuit-level parameters of the model. Finally, an architectural simulation was built in VHDL-AMS. The frequency scaling described by σ, combined with the device/circuit-level parameters predicts the overall power and performance scaling of parallel architectures mapped to the array

Mechanism of the second stage of human parturition

The mechanism of the second stage of human parturition has already been the subject of numerous works, and on many aspects of the problem the treatment has been exhaustive. There are matters, however which still call for inquiry. Further evidence seems desirable relative to the form of the dilated pelvic canal; the direction of uterine pressure may be said to be unknown: given a variable direction of pressure proof is awanting of its influence, or otherwise, on the mechanism; the known effect of a uniform pressure on a curved surface needs application to the mechanism of labour: it is worth while to attempt to unravel the congeries of movements which go by the names of flexion and extension; the difficult problem bf lateral obliquities of the fetal head remains where it was forty years ago; the development of the mechanism at the vulvar outlet may be capable of modification in a manner favourable to easier birth. These and other matters are gone over in the pages that follow.A definition of what is meant by the second stage is not easy if regard is had to every possibility/ possibility. In most labours the second stage comprehends the period which elapses after the os uteri is fully dilated and the membranes are ruptured until the child is completely born. It is obvious, however, that the mechanical phenomena cf the second stage are able to be developed before the os is wide open, and after full dilation before the membranes are ruptured, at any rate until a late period of the second staged The "expulsïve period" of the Germans also is not sufficiently general at least in its clinical manifestations, for the evidence - abdominal action - may be awantingd Nor is it adequate to maintain that the passage of the individual segments of the fetus through the vaginal and vulvar canals constitutes the second stage. For the present purpose the second stage is defined as a period which begins when the fetus is compelled to exercise an uncertain quantity of pressure upon the upper part of the vaginal wall and which lasts until, the child is entirely born.The present thesis is divided into six sections and two appendices. The first section deals with the form of the pelvic canal, the second treats of the direction of uterine and abdominal pressure, in the third the mechanism of flexion is considered in the fourth lateral obliquity of the fetal head, the fifth is devoted to internal rotation; while the sixth is concerned with the mechanism of extension and the protection of the perineum. In the first appendix a number of simple experiments is described, and in the second are set forth tables of angular distances derived from the published reproductions of frozen sections. Finally a short summary is given of the results embodied in the thesis

On the waterfront : water distribution, technology and agrarian change in a South Indian canal irrigation system

This book discusses water distribution in the Tungabhadra Left Bank Canal irrigation system in Raichur district, Karnataka, India. The system is located in interior South India, where rainfall is limited (approximately 600 mm annually) and extremely variable. The region suffered from failed harvests and famines in the past. A large scale irrigation system was constructed to solve these problems. The system is operational since 1953 and was completed in 1968. The area to be irrigated is 240,000 ha.The Tungabhadra Left Bank Canal is a protective irrigation system. It has been designed to spread available water thinly over a large area. It involves supplementary or partial irrigation. Crop water requirements are not fully met. In a particular agricultural season only part of the area is irrigated. Not production per unit area is maximised, but production per unit water.The last point implies a fundamental contradiction inherent to protective irrigation. For a farmer with a given landholding maximisation of production per unit land is the obvious strategy, instead of contributing to the maximum total product given the volume of water. The most remunerative crops, rice and sugarcane, demand a lot of water. Farmers who have the opportunity therefore appropriate more water than their protective share. As a result others do not get their share. Irrigation water in the Tungabhadra Left Bank Canal, like in many other systems, is unequally distributed.The central theme of the thesis is the day to day occurrence of this unequal distribution of water. The book attempts an interdisciplinary analysis of `water control' at different levels: the tertiary unit, the secondary canal and the main (primary) canal. The technical/physical, organisational and socio-economic/political dimensions of water control are related. The central research question is the following.How do the pattern of commoditisation, the form of state regulation and the characteristics of the technical infrastructure shape, and how are they in turn shaped by, the forms of organisation of water distribution in the Tungabhadra Left Bank Canal irrigation system?The method is that of an intensive case study. The research started at the local level with the study of water distribution in a number of tertiary units (local irrigation units in which farmers distribute water among themselves), which were located in the upstream and downstream part of the irrigation system, and with a certain degree of water scarcity. The assumption was that scarcity would induce organisation.After research at this level the investigations gradually moved against the current onto the canal system and the distribution points located there, to the offices of the officials of the Irrigation Department who manage this part of the system, to the houses of politicians, to the shops of traders in seeds and fertiliser, and even to the High Court and Parliament of Karnataka. Mainly social-anthropological research techniques were used.The book has ten chapters. After an introduction chapter 2 discusses the theoretical framework of the analysis. Chapters 3 to 5 give background information on the phenomenon protective irrigation, the design of the system, and the socio-economic development in the region as a result of the introduction of irrigation. Chapters 6 to 9 are the core of the thesis. They discuss water distribution practices at different levels. Chapter 10 presents the conclusions and discusses the possibility of reform of the present situation with regard to water management.Chapter 2 introduces the two central concepts of the book. The first is the notion that irrigation systems are sociotechnical systems. They are heterogenous and complex because they consist of many different types of elements, which are related to each other in multifarious ways. The second concept is water control. Three dimensions of water control are distinguished: the technical/physical dimension, the organisational dimension and the socio-economic/political dimension. The central assumption is that these three dimensions are intimately related. Water control in irrigation is described as an example of politically contested resource use. With this description the importance of the social relations of power in the use of irrigation water is emphasised.Chapter 3 explains the meaning of protection and localisation. The notion of protection originated in British colonial irrigation policy. Three meanings of it are identified: 1) the general meaning of the function of irrigation to protect against drought/crop failure and famine), 2) protective irrigation as a financial-administrative class of irrigation works in the colonial period, and 3) protective irrigation as a specific type of irrigation in the technical, organisational and socio-economic/political sense. In South India, localisation is part of protection. Localisation is a form of land use planning in which the government legally prescribes which crops farmers can and cannot grow with the irrigation water.It is remarkable that the protection objective has remained a central element of Indian irrigation policy, also after independence, despite the (recognised) practice of unequal water distribution. The explanation of this persistence is found is the populist nature of the Indian political system. Politicians act as resource brokers who can secure their political support, among other ways, by getting canals constructed to their constituencies. At the same time they depend primarily on the category of large farmers within their constituency, who are the ones who tend to appropriate water above their protective share. For this reason politicians do not take action against unequal distribution. Because of the influence of politicians on their work, the officials of the Irrigation Department also find themselves in a difficult position.The genesis of the Tungabhadra Left Bank Canal is described in chapter 4. The history of the system starts in the period 1850-1860. The implementation of the plans made in that period and after it for a canal in Raichur district, was complicated by the relationship between Madras Presidency, directly ruled by the British, and the Nizam's Dominions, a formally independent Princely State. The Tungabhadra river was the border river of these two territories. The construction of a dam across it for creating a reservoir required agreement of both governments. Prolonged political negotiation was necessary to come to an agreement on the sharing of the available water. Despite the dominance of Madras presidency it was finally decided to share the water on a 50/50 basis. In 1944 an agreement was signed that allowed the start of the project, but negotiation protracted till 1976, among other things as a result of the reorganisation of the Indian States after independence.In 1945 construction of the project started. Once the available volume of water had been agreed, the further design was mainly done by engineers with little external influence. The cropping pattern was protective from the beginning, and in choice of canal alignments cost of construction was the major consideration. Social boundaries, like those of villages and farms, were not taken into consideration; topography and soil type have determined the design. The explanation of this lies in the very high social status of engineers in this period which made doubting their decisions impossible, and in the absence of institutions for discussion and negotiation regarding design elements.The introduction of irrigation in Raichur district has resulted in rapid economic development, which is described in chapter 5. Irrigation has induced the occurrence of intensive commercialised agricultural cultivation with high productivity. The migration of farmers from the neighbouring state of Andhra Pradesh to the new irrigation system has played a key role in this development. The migrant farmers came with sufficient investment capital and knowledge of irrigated agriculture, and started a farming system based on rice cultivation, and sugarcane to a lesser extent. Initially the local population had insufficient means for investment. The migrants bought land from local farmers. The larger local farmers used the returns of their land sales to invest in the development of their remaining land for irrigation (levelling, making field bunds). There has been a massive transfer of land to migrant farmers. In the course of time migrant as well as local farmers started to invest in pump irrigation, lifting water from the river and natural drains.A geographical pattern has emerged in which rich and middle peasants mainly have land in the upstream reaches of the canals, and small and poor peasants mainly in the downstream parts (the chapter first develops a typology of these four categories of farmers). Notwithstanding this general correlation of location and socio-economic class, the exact relationship differs from locality to locality. Migrant farmers could not always obtain land in the geographically most favourable locations. Sometimes water scarcity developed in areas where sufficient water was available earlier. The process of the relocation of farms in relation to access to water, continues to this day through the mechanisms of purchase and sale of land, the transfer of land in dowries, and through the acquisition of land by extending loans with land as collateral. The process of agrarian change can not be fully understood without incorporation of this inherent spatial dimension.Chapter 6 is the first chapter on day to day water distribution practices. It analyses events at the level of the tertiary unit, within which farmers distribute water among themselves. It was found that in many cases detailed systems of rules existed for rotational water distribution. These are based on the principles of zoning of the irrigated command area, and on a fixed irrigation time per unit area. The rules are used in periods of water scarcity. Outside these periods irrigation takes place on the basis of mutual agreement.Despite the fact that these rules incorporate equity principles, strongly unequal water distribution can be observed. The reasons for this are that the rules only refer to the supply of water, and that they are not applied continuously. The demand for water is differentiated. Small, downstream farmers adjust their crop choice to the anticipation that they will lose conflicts with large farmers on the distribution of water. Small farmers grow crops that demand less water, and thus avoid conflicts. However, these crops are also less remunerative. The anticipation is the product of the dependence of small farmers on large farmers for obtaining credit and for employment for themselves and their family members. Large farmers also act as representatives of the local irrigation unit in discussions with the Irrigation Department and in other activities to safeguard water supply.Water distribution at the level of the secondary canal, called distributary in India, is discussed in chapter 7 (organisational aspects) and chapter 8 (technical aspects). Chapter 7 describes which rules for rotational water distribution have emerged in the interaction of the Irrigation Department officials who manage these canals, and the water users. In many secondary canals rules for rotation exist, which are, like those at tertiary level, mobilised in times of scarcity. At this level the rules also do not accomplish equity in water distribution. They express the power balance between users in different parts of the irrigated area, and that between water users and the government administration.In contrast to what is often assumed, corruption is not the dominant mechanism in water distribution at secondary level in the Tungabhadra Left Bank Canal. The problematic relationship between government managers and water users are not translated into financial transactions, but into political mediation. In certain circumstances local politicians (members of parliament) can play an important role in water management. Politicians depend on the political support of farmers. In exchange for their votes farmers can ask the politician to influence the behaviour of Irrigation Department staff. The local members of parliament's power over the Irrigation Department staff is based on their influence on the three-yearly (or more frequent) transfer of government officials. In this way a `triangle of accommodation' emerges, in which none of the parties involved (farmers, officials and politicians) has absolute control, and in which continuous negotiation is necessary about the distribution of water.Chapter 8 concentrates on the structure that links the secondary canal with the local irrigation unit: the pipe outlet structure. Because the discharge that flows from the secondary canal to the field channel through the pipe of the pipe outlet structure, depends on the upstream as well as the downstream water level, and on the cross section of the pipe (which can be adjusted with a shutter), it is practically impossible to regulate the discharge with any degree of precision. As a result it is unknown how much water is exactly diverted by the pipe outlet structures. Why this type of outlet structure remains in use, and have not been replaced by outlet structures used elsewhere in India that are more fit for the task of equitable distribution, is not completely clear.In practice there is substantial variation in the precise characteristics of the pipe outlet structure: the robustness of construction (concrete, stones and mortar), the location of the shutter (visible or non-visible, accessible or non-accessible), the type of lock or locks, and other characteristics. This variation expresses water distribution practices and problems along the canal. The characteristics and the state of the outlet structures are an expression of the relationships between different groups of farmers along the canal and between farmers and the Irrigation Department.The last chapter on water distribution practices, chapter 9, discusses the process of institutional change within the Irrigation Department in relation to main canal management. In a period of two years with extreme water shortage (1988-1990) a number of institutional changes took place that have improved water supply to the downstream parts of the canal. The original rules for distribution of water based on the localisation pattern have been abandoned. To replace these, new rules have been adopted that on the one hand consolidate inequality, but on the other hand provide a more realistic basis for negotiating water supply to the downstream part of the canal. As a result of the introduction of these new rules water supply to the downstream part has been improved, particularly it has become more stable.The concluding chapter, chapter 10, gives a summary reply to the central research question, and discusses the implications of the analysis for reform of irrigation management. It is argued that the analysis has identified both a number of structural limitations or hurdles for reform, and has shown that the day to day practice of water distribution provides opportunities for change. The opportunities are related to the capacity for self-management of water users, the joint formulation of rules for distribution by farmers and Irrigation Department staff, and the technical creativity and the possibility of institutional change within the Irrigation Department.After this the different perspectives that exist on the generally felt need for reform are discussed. These perspectives vary from technical and managerial arguments for `good management', economic arguments for `efficient management', ecological arguments for `sustainable management', to political arguments for `egalitarian and democratic' management. An attempt is made to describe a comprehensive approach in which technical, organisational, economic and political elements are intertwined.As regards the irrigation policy reform situation in Karnataka it is argued that more attention for the participation of water users and other interest groups in the formulation of policy is necessary. At present, efforts to change policy and practice take place in a rather isolated manner at high levels in the government, or in individual, local situations in irrigation systems. The creation of a broad support base for reform in society is considered a priority.Finally a number of research topics are listed and briefly discussed that could contribute to the reform agenda. These are the design process of canal irrigation technology, the political dimension of irrigation, and the issue of use(r) rights. This research should be situated in the daily practice of water management, that is, on the waterfront.</p