abstract: A good production schedule in a semiconductor back-end facility is critical for the on time delivery of customer orders. Compared to the front-end process that is dominated by re-entrant product flows, the back-end process is linear and therefore more suitable for scheduling. However, the production scheduling of the back-end process is still very difficult due to the wide product mix, large number of parallel machines, product family related setups, machine-product qualification, and weekly demand consisting of thousands of lots. In this research, a novel mixed-integer-linear-programming (MILP) model is proposed for the batch production scheduling of a semiconductor back-end facility. In the MILP formulation, the manufacturing process is modeled as a flexible flow line with bottleneck stages, unrelated parallel machines, product family related sequence-independent setups, and product-machine qualification considerations. However, this MILP formulation is difficult to solve for real size problem instances. In a semiconductor back-end facility, production scheduling usually needs to be done every day while considering updated demand forecast for a medium term planning horizon. Due to the limitation on the solvable size of the MILP model, a deterministic scheduling system (DSS), consisting of an optimizer and a scheduler, is proposed to provide sub-optimal solutions in a short time for real size problem instances. The optimizer generates a tentative production plan. Then the scheduler sequences each lot on each individual machine according to the tentative production plan and scheduling rules. Customized factory rules and additional resource constraints are included in the DSS, such as preventive maintenance schedule, setup crew availability, and carrier limitations. Small problem instances are randomly generated to compare the performances of the MILP model and the deterministic scheduling system. Then experimental design is applied to understand the behavior of the DSS and identify the best configuration of the DSS under different demand scenarios. Product-machine qualification decisions have long-term and significant impact on production scheduling. A robust product-machine qualification matrix is critical for meeting demand when demand quantity or mix varies. In the second part of this research, a stochastic mixed integer programming model is proposed to balance the tradeoff between current machine qualification costs and future backorder costs with uncertain demand. The L-shaped method and acceleration techniques are proposed to solve the stochastic model. Computational results are provided to compare the performance of different solution methods. / Dissertation/Thesis / Ph.D. Industrial Engineering 2011

The diploma thesis deals with the design, creation and implementation of a software application in the corporate environment of Velká Pecka s.r.o., better known as Rohlík. The first goal is to analyze the given company and find its shortcomings. The second, the main one, is to create and implement a software, which would eliminate them. The resulting solution is a mobile application, which improves issue reporting in their warehouses, thus saving resources overall.

This paper addresses two different aspects of the subject known as knowledge bases, or knowledge graphs. A knowledge base is defined as a comprehensive semantically organized machine-readable collection of universally relevant or domain-specific entities, classes, and facts. The objective of this paper is to explore how a knowledge base can be used to gain information about an entity. First we present one way to access information from the knowledge base using a back-end interface. This back-end interface takes simple parameters as input which are used to query the knowledge base. The main objective here is to be able to access the right entity, to be able to answers the questions correctly.  After that follows a discussion about the need for knowledge bases and possible uses. The discussions will partly be based on results from our implementation, but also consider other similar implementation, and interviews with possible users in the business and society.  We conclude that the back-end interface developed performs well enough, with a high precision, to be ran in an unsupervised system. Furthermore we realise that the interface can be improved in several ways by focusing on smaller domains of information. Several different possible uses have been identified. From these uses a market analysis has been done from which we conclude good market possibilities. Some of the key problems with implementing the interface regards the credibility of the information in the knowledge base. This is one of the main problems that needs to be solved to fully implement knowledge bases in business and society. / Den här rapporten tar upp två olika områden som berör knowledge bases. En knowledge base definieras som en omfattande semantiskt organiserad maskinläslig samling av universellt relevanta eller domän-specifika entiteter, klasser, och fakta. Målet med rapporten är att undersöka hur en knowledge base kan användas för att få fram information om en entitet. Först presenteras ett tillvägagångsätt för kommunikation mot en knowledge base med hjälp av ett back-end gränssnitt. Back-end gränssnittet tar enkla parametrar som input och använder dessa för att köra en query mot en knowledge base. Huvudfokus i denna del kommer ligga i att få rätt svar på frågorna och kommer därmed att utvärderas utifrån det. Det andra området som arbetet berör är en diskussion kring hur knowledge bases kan integreras i samhället och näringslivet för att få ut en ökad nytta. Diskussionerna kommer att baseras på resultaten från den första delen av arbetet till viss del, men även andra liknande studier kommer vägas in för att ge ett bredare diskussionsunderlag. Utöver detta baseras också diskussionen på intervjuer med möjliga intressenter inom näringsliv och samhälle. Det utvecklade gränssnittet presterar på en nivå, med hög precision, som vi bedömer tillräcklig för implementering i oövervakade system. Dessutom har flertalet förbättringsområden identifierats. Huvudsakligen berör dessa att mer specifika implementationer kan få högre precision då specifikare kontroller kan genomföras. Flertal möjliga användningsområden har identifierats. Med dessa som grund har en marknadsanalys genomförts som pekar på goda förutsättningar för tekniken. Ett av det största problemen berör trovärdigheten i informationen i knowledge basen. Det är ett problem som måste lösas innan tekniken kan implementeras fullt ut i näringsliv och samhälle.

User experience design is the process of improving the accessibility and use of a product during user’s interaction with it. This study investigates the issues that occur in the coordination of UX design and software development. Furthermore, it examines diverse types of conflicts between UX designers, front-end and back-end developers, factors contributing to these conflicts and their influence on the software development process. The method used in this study is a survey conducted in an online form with a target group of practitioners. The data show that task conflicts are the most common type of conflicts in teams, that gender of a person can influence its awareness of the project status and that age and geographical location do not affect the occurrence of the identified conflicts.

This thesis deals with the issue of attendance recording. The aim of the thesis was to design a solution and then create a hardware terminal for the electronic attendance system. The whole system is based on the latest web technologies using the Raspberry Pi hardware, for the client terminal. Future use of the device is possible for both home and commercial use. The whole system was distributed globaly as Open Source project. The result of thesis is a physical prototype of a client terminal, based on the Raspberry Pi platform, Electron based application for terminal and a web application communicating with the server solution.

Planning and scheduling in semiconductor manufacturing is a difficult problem due to long cycle times, a large number of operational steps, diversified product types, and low-volume high-mix customer demand. This research addresses several problems that arise in the semiconductor industry related to front-end wafer fabrication operations and back-end assembly and test operations. The mathematical models built for these problems turn out to be large-scale mixed integer programs and hard to solve with exact methods. The major contribution of this research is to combine mathematical programming with metaheuristics to find high quality solutions within the time limits imposed by the industrial engineers who oversee the fabrication and test facilities. In order to reduce the size of problems that arise in practice, it is common to cluster similar product types into groups that reflect their underlying technology. The first part of the research is aimed at developing a greedy randomized adaptive search procedure (GRASP) coupled with path relinking (PR) to solve the capacitated clustering problem. The model is generic and can be applied in many different situations. The objective is to maximize a similarity measure within each cluster such that the sum of the weights associated with the product types does not exceed the cluster capacity in each case. In phase I, both a heaviest weight edge (HWE) algorithm and a constrained minimum cut (CMC) algorithm are used to select seeds for initializing the clusters. Feasible solutions are obtained with the help of a self-adjusting restricted candidate list. In phase II, three neighborhoods are defined and explored using the following strategies: cyclic neighborhood search, variable neighborhood descent, and randomized variable neighborhood descent (RVND). The best solutions found are stored in an elite pool. In a post-processing step, PR coupled with local search is applied to the pool members to cyclically generate paths between each pair. The elite pool is updated after each iteration and the procedure ends when no further improvement is possible. After grouping the product types into technologies, a new model is presented for production planning in a high volume fab that uses quarterly commitments to define daily target outputs. Rather than relying on due dates and priority rules to schedule lot starts and move work in process through the shop, the objective is to minimize the sum of the deviations between the target outputs and finished goods inventory. The model takes the form of a large-scale linear program that is intractable for planning horizons beyond a few days. Both Lagrangian relaxation and Benders decomposition were investigated but each proved ineffective. As a consequence, a methodology was developed which was more tailored to the problem’s structure. This involved creating weekly subproblems that were myopic but could be solved to optimality within a few minutes, and then postprocessing the results with a decomposition algorithm to fully utilize the excessive machine time. The heart of the post-processor consists of a rescheduling algorithm and a dispatching heuristic. The third part of the research focuses on the combinatorial problem of machinetooling setup and lot assignments for performing back-end operations. A new model and solution methodology are presented aimed at maximizing the weighted throughput of lots undergoing assembly and test, while ensuring that critical lots are given priority. The problem is formulated as a mixed-integer program and solved again with a GRASP that makes use of linear programming. In phase I of the GRASP, machine-tooling combinations are tentatively fixed and lot assignments are made iteratively to arrive at a feasible solution. This process is repeated many times. In phase II, a novel neighborhood search is performed on a subset of good solutions found in phase I. Using a linear programming-Monte Carlo simulation-based algorithm, new machine-tooling combinations are identified within the neighborhood of the solutions carried over, and improvements are sought by optimizing the corresponding lot assignments. / text

Interconnection layers fabricated during back end of line processing in semiconductor manufacturing involve dry etching of a low-k material and deposition of copper and metal barriers to create copper/dielectric stacks. After plasma etching steps used to form the trenches and vias in the dielectric, post etch residues (PER) that consist of organic polymer, metal oxides and fluorides, form on top of copper and low-k dielectric sidewalls. Currently, most semiconductor companies use semi aqueous fluoride (SAF) based formulations containing organic solvent(s) for PER removal. Unfortunately, these formulations adversely impact the environmental health and safety (EHS) requirements of the semiconductor industry. Environmentally friendly "green" formulations, free of organic solvents, are preferred as alternatives to remove PER. In this work, a novel low temperature molten salt system, referred as deep eutectic solvent (DES) has been explored as a back end of line cleaning (BEOL) formulation. Specifically, the DES system comprised of two benign chemicals, malonic acid (MA) and choline chloride (CC), is a liquid at room temperature. In certain cases, the formulation was modified by the addition of glacial acetic acid (HAc). Using these formulations, selective removal of three types of PER generated by timed CF₄/O₂ etching of DUV PR films on Cu was achieved. Type I PER was mostly organic in character (fluorocarbon polymer type) and had a measured thickness of 160 nm. Type II PER was much thinner (25 nm) and consisted of a mixture of organic and inorganic compounds (copper fluorides). Further etching generated 17 nm thick Type III PER composed of copper fluorides and oxides. Experiments were also conducted on patterned structures. Cleaning was performed by immersing samples in a temperature controlled (30 or 40° C) double jacketed vessel for a time between 1 and 5 minutes. Effectiveness of cleaning was characterized using SEM, XPS and single frequency impedance measurements. Type II and III residues, which contained copper compounds were removed in CC/MA DES within five minutes through dissolution and subsequent complexation of copper by malonic acid. Removal of Type I PER required the addition of glacial acetic acid to the DES formulation. Single frequency impedance measurement appears to be a good in situ method to follow the removal of the residues. High water solubility of the components of the system in conjunction with their environmental friendly nature, make the DES an attractive alternative to SAF.

<p>Copper (Cu) has been used as the main conductor in interconnects due to its low resistivity. However, because of its high diffusivity, diffusion barriers/liners (tantalum nitride/tantalum; TaN/Ta) must be incorporated to surround Cu wires. Otherwise, Cu ions/atoms will drift/diffuse through the inter-metal dielectric (IMD) that separates two distinct interconnects, resulting in circuit shorting and chip failures. The scaling limit of conventional Cu diffusion barriers/liners has become the bottleneck for interconnect technology, which in turn limits the IC performance. The interconnect half-pitch size will reach ~20 nm in the coming sub-5 nm technology nodes. Meanwhile, the TaN/Ta (barrier/liner) bilayer stack has to be > 4 nm to ensure acceptable liner and diffusion barrier properties. Since TaN/Ta occupy a significant portion of the interconnect cross-section and they are much more resistive than Cu, the effective conductance of an ultra-scaled interconnect will be compromised by the thick bilayer. Therefore, two dimensional (2D) layered materials have been explored as diffusion barrier alternatives owing to their atomically thin body thicknesses. However, many of the proposed 2D barriers are prepared at too high temperatures to be compatible with the back-end-of-line (BEOL) technology. In addition, as important as the diffusion barrier properties, the liner properties of 2D materials must be evaluated, which has not yet been pursued. </p> The objective of the thesis is to develop a 2D barrier/liner that overcomes the issues mentioned. Therefore, we first visit various 2D layered materials to understand their fundamental capability as barrier candidates through theoretical calculations. Among the candidates, hexagonal-boron-nitride (h-BN) and molybdenum disulfide (MoS₂) are selected for experimental studies. In addition to studying their fundamental properties to know their potential, we have also developed techniques that can realize low-temperature-grown 2D layered materials. Metal-organic chemical vapor deposition (MOCVD) is adopted for the synthesis of BEOL-compatible MoS₂. The electrical test results demonstrate the promises of integrating 2D layered materials to the state-of-the-art interconnect technology. Furthermore, by considering not only diffusion barrier properties but also liner properties, we develop another 2D layered material, tantalum sulfide (TaS_x), using plasma-enhanced chemical vapor deposition (PECVD). The TaS_x is promising in both barrier and liner aspects and is BEOL-compatible. Therefore, we believed that the conventional TaN/Ta bilayer stack can be replaced with an ultra-thin TaS_x layer to maximize the Cu volume for ultra-scaled interconnects and improve the performance. Furthermore, Since via resistance has become the bottleneck for overall interconnect performance, we study the vertical conduction of TaS_x. Both the intrinsic and extrinsic properties of this material are investigated and engineering approaches to improve the vertical conduction are also tested. Finally, we explore the possibilities of benefiting from 2D materials in other applications and propose directions for future studies.

Open source eller öppen källkod innebär att vem som helst kan se, justera och dela koden. Företag, organisationer och individer investerar såväl tid som resurser att utveckla open source-projekt, där majoriteten av projekten inte genererar någon form av ekonomisk vinning. Pocketsize är en Malmöbaserad webbyrå som har utvecklat ett front-end ramverk vid namn Bolts samt ett automatiseringsverktyg vid namn Toolbelt som avses släppas som open source.Denna studie syftar till att bidra med kunskap om vad det är som driver småföretag, idella organisationer eller individer till investera tid i att utveckla open source-projekt. Därmed har en fallstudie på webbyrån Pocketsize i Malmö gjorts där en analys av ramverket Bolts och verktyget Toolbelt, utvecklat av Pocketsize, har genomförts. Detta för att erhålla kunskap om varför Pocketsize väljer att släppa de open source. Teori och tidigare forskning presenterar aspekter som motiverande faktorer och drivkrafter bakom utveckling av open source-projekt. Studien har har antagit ett kvalitativt perspektiv där observationer och semistrukturerade intervjuer har gjorts för att kartlägga handlingsmönster och för att återge hur en individ tänker och resonerar kring ämnet. Resultatet redogör för hur utvecklare ofta skapar en produkt utifrån sina egna behov samt hur känslan av altruism och att viljan att ”ge tillbaka” till open source-communityt är några av de största motiverande faktorer och drivkrafter bakom att bidra till open source-projekt. / Open source or open source-code means that anyone can view, adjust and share the code. Companies, organizations and individuals invest their time and resources to develop open source projects, where the majority of projects doesn’t even generate any kind of financial gain. Pocketsize is a Malmö based web agency that has developed a front-end framework called Bolts as well as an automation tool called Toolbelt intended to be released as open source.This study aims to contribute knowledge of what drives small businesses, non-profit organizations or individuals to invest time and resources in developing open source projects. Therefore, a case study has been made at the web development agency Pocketsize in Malmö, where an analysis of the Bolts framework and Toolbelt automation tool that Pocketsize has developed has been conducted. In an attempt to understand why Pocketsize chooses to release them as open source. Theory and previous research presents aspects as motivational factors and driving forces behind the development of open source projects. The study has adopted a qualitative perspective where observations and semi structured interviews have been made to map action patterns and to reflect how an individual contemplates on the subject. The result states that developers often create aproduct based on their own needs and how a feeling of altruism and the willingness to “pay it forward” to the open source community are some of the major motivatiors and driving forces behind contributing to open source projects.

Fabrication of current generation integrated circuits involves the creation of multilevel copper/low-k dielectric structures during the back end of line processing. This is done by plasma etching of low-k dielectric layers to form vias and trenches, and this process typically leaves behind polymer-like post etch residues (PER) containing copper oxides, copper fluorides and fluoro carbons, on underlying copper and sidewalls of low-k dielectrics. Effective removal of PER is crucial for achieving good adhesion and low contact resistance in the interconnect structure, and this is accomplished using wet cleaning and rinsing steps. Currently, the removal of PER is carried out using semi-aqueous fluoride based formulations. To reduce the environmental burden and meet the semiconductor industry's environmental health and safety requirements, there is a desire to completely eliminate solvents in the cleaning formulations and explore the use of organic solvent-free formulations.The main objective of this work is to investigate the selective removal of PER over copper and low-k (Coral and Black Diamond®) dielectrics using all-aqueous dilute HF (DHF) solutions and choline chloride (CC) - urea (U) based deep eutectic solvent (DES) system. Initial investigations were performed on plasma oxidized copper films. Copper oxide and copper fluoride based PER films representative of etch products were prepared by ashing g-line and deep UV photoresist films coated on copper in CF4/O2 plasma. PER removal process was characterized using scanning electron microscopy and X-ray photoelectron spectroscopy and verified using electrochemical impedance spectroscopy measurements.A PER removal rate of ~60 Å/min was obtained using a 0.2 vol% HF (pH 2.8). Deaeration of DHF solutions improved the selectivity of PER over Cu mainly due to reduced Cu removal rate. A PER/Cu selectivity of ~20:1 was observed in a 0.05 vol% deaerated HF (pH 3). DES systems containing 2:1 U/CC removed PER at a rate of ~10 and ~20 Å/min at 40 and 70oC respectively. A mixture of 10-90 vol% de-ionized water (W) with 2:1 U/CC in the temperature range of 20 to 40oC also effectively removed PER. Importantly, etch rate of copper and low-k dielectric in DES formulations were lower than that in conventional DHF cleaning solutions.